WorldWideScience

Sample records for active regions observed

  1. OBSERVING CORONAL NANOFLARES IN ACTIVE REGION MOSS

    The High-resolution Coronal Imager (Hi-C) has provided Fe XII 193Å images of the upper transition region moss at an unprecedented spatial (∼0.''3-0.''4) and temporal (5.5 s) resolution. The Hi-C observations show in some moss regions variability on timescales down to ∼15 s, significantly shorter than the minute-scale variability typically found in previous observations of moss, therefore challenging the conclusion of moss being heated in a mostly steady manner. These rapid variability moss regions are located at the footpoints of bright hot coronal loops observed by the Solar Dynamics Observatory/Atmospheric Imaging Assembly in the 94 Å channel, and by the Hinode/X-Ray Telescope. The configuration of these loops is highly dynamic, and suggestive of slipping reconnection. We interpret these events as signatures of heating events associated with reconnection occurring in the overlying hot coronal loops, i.e., coronal nanoflares. We estimate the order of magnitude of the energy in these events to be of at least a few 1023 erg, also supporting the nanoflare scenario. These Hi-C observations suggest that future observations at comparable high spatial and temporal resolution, with more extensive temperature coverage, are required to determine the exact characteristics of the heating mechanism(s).

  2. Observing coronal nanoflares in active region moss

    Testa, Paola; Martinez-Sykora, Juan; DeLuca, Ed; Hansteen, Viggo; Cirtain, Jonathan; Winebarger, Amy; Golub, Leon; Kobayashi, Ken; Korreck, Kelly; Kuzin, Sergey; Walsh, Robert; DeForest, Craig; Title, Alan; Weber, Mark

    2013-01-01

    The High-resolution Coronal Imager (Hi-C) has provided Fe XII 193A images of the upper transition region moss at an unprecedented spatial (~0.3-0.4 arcsec) and temporal (5.5s) resolution. The Hi-C observations show in some moss regions variability on timescales down to ~15s, significantly shorter than the minute scale variability typically found in previous observations of moss, therefore challenging the conclusion of moss being heated in a mostly steady manner. These rapid variability moss regions are located at the footpoints of bright hot coronal loops observed by SDO/AIA in the 94A channel, and by Hinode/XRT. The configuration of these loops is highly dynamic, and suggestive of slipping reconnection. We interpret these events as signatures of heating events associated with reconnection occurring in the overlying hot coronal loops, i.e., coronal nanoflares. We estimate the order of magnitude of the energy in these events to be of at least a few $10^{23}rg, also supporting the nanoflare scenario. These Hi-C...

  3. Cooling Active Region Loops Observed With SXT and TRACE

    Winebarger, A R; Winebarger, Amy R.; Warren, Harry P.

    2005-01-01

    An Impulsive Heating Multiple Strand (IHMS) Model is able to reproduce the observational characteristics of EUV (~ 1 MK) active region loops. This model implies that some of the loops must reach temperatures where X-ray filters are sensitive (> 2.5 MK) before they cool to EUV temperatures. Hence, some bright EUV loops must be preceded by bright X-ray loops. Previous analysis of X-ray and EUV active region observations, however, have concluded that EUV loops are not preceded by X-ray loops. In this paper, we examine two active regions observed in both X-ray and EUV filters and analyze the evolution of five loops over several hours. These loops first appear bright in the X-ray images and later appear bright in the EUV images. The delay between the appearance of the loops in the X-ray and EUV filters is as little as 1 hour and as much as 3 hours. All five loops appear as single ``monolithic'' structures in the X-ray images, but are resolved into many smaller structures in the (higher resolution) EUV images. The ...

  4. Active region upflows. I. Multi-instrument observations

    Vanninathan, K.; Madjarska, M. S.; Galsgaard, K.; Huang, Z.; Doyle, J. G.

    2015-12-01

    Context. We study upflows at the edges of active regions, called AR outflows, using multi-instrument observations. Aims: This study intends to provide the first direct observational evidence of whether chromospheric jets play an important role in furnishing mass that could sustain coronal upflows. The evolution of the photospheric magnetic field, associated with the footpoints of the upflow region and the plasma properties of active region upflows is investigated with the aim of providing information for benchmarking data-driven modelling of this solar feature. Methods: We spatially and temporally combine multi-instrument observations obtained with the Extreme-ultraviolet Imaging Spectrometer on board the Hinode, the Atmospheric Imaging Assembly and the Helioseismic Magnetic Imager instruments on board the Solar Dynamics Observatory and the Interferometric BI-dimensional Spectro-polarimeter installed at the National Solar Observatory, Sac Peak, to study the plasma parameters of the upflows and the impact of the chromosphere on active region upflows. Results: Our analysis shows that the studied active region upflow presents similarly to those studied previously, i.e. it displays blueshifted emission of 5-20 kms-1 in Fe xii and Fe xiii and its average electron density is 1.8 × 109 cm-3 at 1 MK. The time variation of the density is obtained showing no significant change (in a 3σ error). The plasma density along a single loop is calculated revealing a drop of 50% over a distance of ~20 000 km along the loop. We find a second velocity component in the blue wing of the Fe xii and Fe xiii lines at 105 kms-1 reported only once before. For the first time we study the time evolution of this component at high cadence and find that it is persistent during the whole observing period of 3.5 h with variations of only ±15 kms-1. We also, for the first time, study the evolution of the photospheric magnetic field at high cadence and find that magnetic flux diffusion is

  5. Multi-wavelength Observations of Solar Active Region NOAA 7154

    Bruner, M. E.; Nitta, N. V.; Frank. Z. A.; Dame, L.; Suematsu, Y.

    2000-01-01

    We report on observations of a solar active region in May 1992 by the Solar Plasma Diagnostic Experiment (SPDE) in coordination with the Yohkoh satellite (producing soft X-ray images) and ground-based observatories (producing photospheric magnetograms and various filtergrams including those at the CN 3883 A line). The main focus is a study of the physical conditions of hot (T is approximately greater than 3 MK) coronal loops at their foot-points. The coronal part of the loops is fuzzy but what appear to be their footpoints in the transition region down to the photosphere are compact. Despite the morphological similarities, the footpoint emission at 10(exp 5) K is not quantitatively correlated with that at approximately 300 km above the tau (sub 5000) = 1 level, suggesting that the heat transport and therefore magnetic field topology in the intermediate layer is complicated. High resolution imaging observations with continuous temperature coverage are crucially needed.

  6. Spectroscopic Observations of Fe XVIII in Solar Active Regions

    Teriaca, Luca; Curdt, Werner

    2012-01-01

    The large uncertainties associated with measuring the amount of high temperature emission in solar active regions represents a significant impediment to making progress on the coronal heating problem. Most current observations at temperatures of 3 MK and above are taken with broad band soft X-ray instruments. Such measurements have proven difficult to interpret unambiguously. Here we present the first spectroscopic observations of the Fe XVIII 974.86 AA emission line in an on-disk active region taken with then SUMER instrument on SOHO. Fe XVIII has a peak formation temperature of 7.1 MK and provides important constraints on the amount of impulsive heating in the corona. Detailed evaluation of the spectra and comparison of the SUMER data with soft X-ray images from the XRT on Hinode confirm that this line is unblended. We also compare the spectroscopic data with observations from the AIA 94 AA channel on SDO. The AIA 94 AA channel also contains Fe XVIII, but is blended with emission formed at lower temperature...

  7. Active region upflows: 1. Multi-instrument observations

    Vanninathan, K.; Madjarska, M. S.; Galsgaard, K.; Huang, Z; Doyle, J. G.

    2015-01-01

    Upflows at the edges of active regions (ARs) are studied by spatially and temporally combining multi-instrument observations obtained with EIS/Hinode, AIA and HMI/SDO and IBIS/NSO, to derive their plasma parameters. This information is used for benchmarking data-driven modelling of the upflows (Galsgaard et al., 2015). The studied AR upflow displays blueshifted emission of 5-20 km/s in Fe XII and Fe XIII and its average electron density is 1.8x10^9 cm^3 at 1 MK. The time variation of the dens...

  8. Active region upflows: 1. Multi-instrument observations

    Vanninathan, K; Galsgaard, K; Huang, Z; Doyle, J G

    2015-01-01

    Upflows at the edges of active regions (ARs) are studied by spatially and temporally combining multi-instrument observations obtained with EIS/Hinode, AIA and HMI/SDO and IBIS/NSO, to derive their plasma parameters. This information is used for benchmarking data-driven modelling of the upflows (Galsgaard et al., 2015). The studied AR upflow displays blueshifted emission of 5-20 km/s in Fe XII and Fe XIII and its average electron density is 1.8x10^9 cm^3 at 1 MK. The time variation of the density shows no significant change (in a 3sigma error). The plasma density along a single loop drops by 50% over a distance of 20000 km. We find a second velocity component in the blue wing of the Fe XII and Fe XIII lines at 105 km/s. This component is persistent during the whole observing period of 3.5 hours with variations of only 15 km/s. We also study the evolution of the photospheric magnetic field and find that magnetic flux diffusion is responsible for the formation of the upflow region. High cadence Halpha observatio...

  9. SPECTROSCOPIC OBSERVATIONS OF Fe XVIII IN SOLAR ACTIVE REGIONS

    Teriaca, Luca; Curdt, Werner [Max-Planck-Institut fuer Sonnensystemforschung, Max-Planck-Str. 2, 37191 Katlenburg-Lindau (Germany); Warren, Harry P. [Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States)

    2012-08-01

    The large uncertainties associated with measuring the amount of high temperature emission in solar active regions (ARs) represents a significant impediment to making progress on the coronal heating problem. Most current observations at temperatures of 3 MK and above are taken with broadband soft X-ray instruments. Such measurements have proven difficult to interpret unambiguously. Here, we present the first spectroscopic observations of the Fe XVIII 974.86 A emission line in an on-disk AR taken with the SUMER instrument on SOHO. Fe XVIII has a peak formation temperature of 7.1 MK and provides important constraints on the amount of impulsive heating in the corona. Detailed evaluation of the spectra and comparison of the SUMER data with soft X-ray images from the X-Ray Telescope on Hinode confirm that this line is unblended. We also compare the spectroscopic data with observations from the Atmospheric Imaging Assembly (AIA) 94 A channel on the Solar Dynamics Observatory. The AIA 94 A channel also contains Fe XVIII, but is blended with emission formed at lower temperatures. We find that it is possible to remove the contaminating blends and form relatively pure Fe XVIII images that are consistent with the spectroscopic observations from SUMER. The observed spectra also contain the Ca XIV 943.63 A line that, although a factor 2-6 weaker than the Fe XVIII 974.86 A line, allows us to probe the plasma around 3.5 MK. The observed ratio between the two lines indicates (isothermal approximation) that most of the plasma in the brighter Fe XVIII AR loops is at temperatures between 3.5 and 4 MK.

  10. Spectroscopic Observations of Fe XVIII in Solar Active Regions

    Teriaca, Luca; Warren, Harry P.; Curdt, Werner

    2012-08-01

    The large uncertainties associated with measuring the amount of high temperature emission in solar active regions (ARs) represents a significant impediment to making progress on the coronal heating problem. Most current observations at temperatures of 3 MK and above are taken with broadband soft X-ray instruments. Such measurements have proven difficult to interpret unambiguously. Here, we present the first spectroscopic observations of the Fe XVIII 974.86 Å emission line in an on-disk AR taken with the SUMER instrument on SOHO. Fe XVIII has a peak formation temperature of 7.1 MK and provides important constraints on the amount of impulsive heating in the corona. Detailed evaluation of the spectra and comparison of the SUMER data with soft X-ray images from the X-Ray Telescope on Hinode confirm that this line is unblended. We also compare the spectroscopic data with observations from the Atmospheric Imaging Assembly (AIA) 94 Å channel on the Solar Dynamics Observatory. The AIA 94 Å channel also contains Fe XVIII, but is blended with emission formed at lower temperatures. We find that it is possible to remove the contaminating blends and form relatively pure Fe XVIII images that are consistent with the spectroscopic observations from SUMER. The observed spectra also contain the Ca XIV 943.63 Å line that, although a factor 2-6 weaker than the Fe XVIII 974.86 Å line, allows us to probe the plasma around 3.5 MK. The observed ratio between the two lines indicates (isothermal approximation) that most of the plasma in the brighter Fe XVIII AR loops is at temperatures between 3.5 and 4 MK.

  11. Multiple wavelength observations of a solar active region

    The Solar Maximum Mission Satellite, the Sacramento Peak Vacuum Tower Telescope, the Very Large Array and the Westerbork Synthesis Radio Telescope have been used to observe active region AR 2490 on two consecutive days at soft X-ray, ultraviolet, optical and radio wavelengths (2, 6, and 20 cm), with comparable angular resolution (2'' to 15'') and field of view (4' x 4'). The radio emissions at lambda = 6 cm and 20 cm show a double structure in which one component is associated with bright Hα plage, C IV and soft X-ray emission, and the other component is associated only with sunspots. No radiation at lambda = 2 cm is detected in this latter component. Coronal temperature and emission measure derived from X-ray lines indicate that the dominant radiation mechanism of the plage-associated component is due to thermal bremsstrahlung while the gyroresonance absorption coefficient must be invoked to account for the high brightness temperature (Tsub(b) approx. equal to 2 x 106 K) observed in the sunspot associated component. The high magnetic field strength needed (600 G at a level where T approx. equal to 2 x 106 K) is explained assuming a thin transition zone, in order to reach a high electron temperature close to the sunspot, where the magnetic fields are stronger. A higher temperature gradient above sunspots is also consistent with the absence of detectable C IV emission. (orig.)

  12. Very Large Array (VLA) observations of solar active regions

    Very Large Array (VLA) synthesis maps of the total intensity and the circular polarization of three active regions at 6 cm wavelength are presented. The radiation from each active region is dominated by a few intense cores with angular sizes of approximately 0.5', brightness temperatures of approximately 106 K, and degrees of circular polarization of 30 to 90%. Some of the core sources within a given active region exhibit opposite senses of circular polarization, suggesting the feet of magnetic dipoles, and the high brightness temperatures suggest that these magnetic structures belong to the low solar corona. Comparisons between the VLA maps of circular polarization and Zeeman effect magnetograms of the lower lying photosphere are presented. There is an excellent correlation between the magnetic structures inferred by the two methods, indicating that synthesis maps of circular polarization at 6 cm can be used to delineate magnetic structures in the low solar corona. (Auth.)

  13. Flarelike brightenings of active region loops observed with SUMER

    Wang, T J; Solanki, S K; Curdt, W

    2015-01-01

    Coronal loops on the east limb of the Sun were observed by SUMER on SOHO for several days. Small flare-like brightenings are detected very frequently in the hot flare line Fe~{\\small XIX}. We find that the relatively intense events are in good coincidence with the transient brightenings seen by Yohkoh/SXT. A statistical analysis shows that these brightenings have durations of 5-84 min and extensions along the slit of 2-67 Mm. The integrated energy observed in Fe~{\\small XIX} for each event is in the range of $3\\times10^{18}-5\\times10^{23}$ ergs, and the estimated thermal energy ranges from $10^{26}-10^{29}$ ergs. Application of the statistical method proposed by Parnell \\& Jupp (2000) yields a value of 1.5 to 1.8 for the index of a power law relation between the frequency of the events and the radiated energy in Fe~{\\small XIX}, and a value of 1.7 to 1.8 for the index of the frequency distribution of the thermal energy in the energy range $>10^{27}$ ergs. We examine the possibility that these small bright...

  14. Coronal upflows from edges of an active region observed with EUV Imaging Spectrometer onboard Hinode

    Kitagawa, Naomasa

    2014-01-01

    In order to better understand the plasma supply and leakage at active regions, we investigated physical properties of the upflows from edges of active region NOAA AR10978 observed with the EUV Imaging Spectrometer (EIS) onboard Hinode. Our observational aim is to measure two quantities of the outflows: Doppler velocity and electron density.

  15. Space-born and ground-based observations of a solar active region and a flare

    The Active Region (AR) 2490 has been observed from June 10 to 12, 1980 by several powerful instruments operating either on the ground (Optical and Radio) and on Solar Maximum Mission Satellite (SMM). A class 1 flare in AR 2490 was observed between June 10 at 2325 UT and June 11 at 0030 UT by the same instruments. The various observations are compared. (Auth.)

  16. A Rapidly Evolving Active Region NOAA 8032 observed on April 15th, 1997

    Shibu K. Mathew; Ashok Ambastha

    2000-09-01

    The active region NOAA 8032 of April 15, 1997 was observed to evolve rapidly. The GOES X-ray data showed a number of sub-flares and two C-class flares during the 8-9 hours of its evolution. The magnetic evolution of this region is studied to ascertain its role in flare production. Large changes were observed in magnetic field configuration due to the emergence of new magnetic flux regions (EFR). Most of the new emergence occured very close to the existing magnetic regions, which resulted in strong magnetic field gradients in this region. EFR driven reconnection of the field lines and subsequent flux cancellation might be the reason for the continuous occurrence of sub-flares and other related activities.

  17. Magnetoseismology of Active Regions using Multi-wavelength Observations from GONG and SDO

    Tripathy, Sushanta; Jain, Kiran; Kholikov, Shukur; Hill, Frank; Cally, Paul

    2016-05-01

    The structure and dynamics of active regions beneath the surface show significant uncertainties due to our limited understanding of the wave interaction with magnetic field. Recent numerical simulations further demonstrate that the atmosphere above the photospheric levels also modifies the seismic observables at the surface. Thus the key to improve helioseismic interpretation beneath the active regions requires a synergy between models and helioseismic inferences from observations. In this context, using data from Global Oscillation Network Group and from Helioseismic Magnetic Imager and Atmospheric Imaging Assembly onboard Solar Dynamics Observatory, we characterize the spatio-temporal power distribution in and around active regions. Specifically, we focus on the power enhancements seen around active regions as a function of wave frequencies, strength, inclination of magnetic field and observation height as well as the relative phases of the observables and their cross-coherence functions. It is expected that these effects will help us to comprehend the interaction of acoustic waves with magnetic field in the solar photosphere.

  18. Determining the solar wind speed above active regions using remote radio-wave observations

    Fainberg, J.; Stone, R. G.; Bougeret, J.-L.

    1983-01-01

    A new technique has made it possible to measure the velocity of portions of the solar wind during its flow outward from the sun. This analysis utilizes spacecraft (ISEE-3) observations of radio emission generated in regions of the solar wind associated with solar active regions. By tracking the source of these radio waves over periods of days, it is possible to measure the motion of the emission regions. Evidence of solar wind acceleration during this outward flow, consistent with theoretical models, has also been obtained.

  19. High spatial resolution FeXII observations of solar active region

    Testa, Paola; Hansteen, Viggo

    2016-01-01

    We use UV spectral observations of active regions with the Interface Region Imaging Spectrograph (IRIS) to investigate the properties of the coronal FeXII 1349.4A emission at unprecedented high spatial resolution (~0.33"). We find that by using appropriate observational strategies (i.e., long exposures, lossless compression), FeXII emission can be studied with IRIS at high spatial and spectral resolution, at least for high density plasma (e.g., post-flare loops, and active region moss). We find that upper transition region (moss) FeXII emission shows very small average Doppler redshifts (v_Dop ~3 km/s), as well as modest non-thermal velocities (with an average ~24 km/s, and the peak of the distribution at ~15 km/s). The observed distribution of Doppler shifts appears to be compatible with advanced 3D radiative MHD simulations in which impulsive heating is concentrated at the transition region footpoints of a hot corona. While the non-thermal broadening of FeXII 1349.4A peaks at similar values as lower resolut...

  20. CAN A LONG NANOFLARE STORM EXPLAIN THE OBSERVED EMISSION MEASURE DISTRIBUTIONS IN ACTIVE REGION CORES?

    All theories that attempt to explain the heating of the high-temperature plasma observed in the solar corona are based on short bursts of energy. The intensities and velocities measured in the cores of quiescent active regions, however, can be steady over many hours of observation. One heating scenario that has been proposed to reconcile such observations with impulsive heating models is the 'long nanoflare storm', where short-duration heating events occur infrequently on many sub-resolution strands; the emission of the strands is then averaged together to explain the observed steady structures. In this Letter, we examine the emission measure distribution predicted for such a long nanoflare storm by modeling an arcade of strands in an active region core. Comparisons of the computed emission measure distributions with recent observations indicate that the long nanoflare storm scenario implies greater than five times more 1 MK emission than is actually observed for all plausible combinations of loop lengths, heating rates, and abundances. We conjecture that if the plasma had 'super coronal' abundances, the model may be able to match the observations at low temperatures.

  1. Magnetic field structures of solar active regions obtained by polarization mapping observation at 32 GHz

    Solar radio polarization mapping observation was made at 32 GHz with an angular resolution of 3.' 6 on February 2 and 4, 1981. The polarization map represents the distribution of the difference between right-handed (R) and left-handed (L) circular polarization components on the sun (R-L). The polarization maps of two days showed that four active regions on the sun had clear bipolar structures, which were consistent with those observed on the magnetograms. The peak value of the circular polarization degree in the active regions lay between 0.4 % and 2.5 %, which suggests that the longitudinal magnetic field strength at the chromospheric level was between 20 G and 140 G. (author)

  2. Non-LTE Inversion of Spectropolarimetric and Spectroscopic Observations of a Small Active-region Filament Observed at the VTT

    Schwartz, P.; Balthasar, H.; Kuckein, C.; Koza, J.; Gömöry, P.; Rybák, J.; Kučera, A.; Heinzel, P.

    2016-04-01

    An active region mini-filament was observed by VTT simultaneously in the HeI 10 830 Å triplet by the TIP 1 spectropolarimeter, in Hα by the TESOS Fabry-Pérot interferometer, and in Ca II 8542 Å by the VTT spectrograph. The spectropolarimetric data were inverted using the HAZEL code and Hα profiles were modelled solving a NLTE radiative transfer in a simple isobaric and isothermal 2D slab irradiated both from bottom and sides. It was found that the mini-filament is composed of horizontal fluxtubes, along which the cool plasma of T˜10 000 K can flow by very large - even supersonic - velocities.

  3. Photospheric and Coronal Observations of Abrupt Magnetic Restructuring in Two Flaring Active Regions

    Petrie, Gordon

    2016-05-01

    For two major X-class flares observed by the Solar Dynamics Observatory (SDO) and the Solar TErrestrial RElations Observatory Ahead (STEREO-A) spacecraft when they were close to quadrature, we compare major, abrupt changes in the photospheric magnetic vector field to changes in the observed coronal magnetic structure during the two flares. The Lorentz force changes in strong photospheric fields within active regions are estimated from time series of SDO Helioseismic and Magnetic Imager (HMI) vector magnetograms. These show that the major changes occurred in each case near the main neutral line of the region and in two neighboring twisted opposite-polarity sunspots. In each case the horizontal parallel field strengthened significantly near the neutral line while the azimuthal field in the sunspots decreased, suggesting that a flux rope joining the two sunspots collapsed across the neutral line with reduced magnetic pressure because of a reduced field twist component. At the same time, the coronal extreme ultraviolet (EUV) loop structure was observed by the Atmospheric Imaging Assembly (AIA) onboard SDO and the Extreme Ultraviolet Imager (EUVI) on STEREO-A to decrease significantly in height during each eruption, discontinuous changes signifying ejection of magnetized plasma, and outward-propagating continuous but abrupt changes consistent with loop contraction. An asymmetry in the observed EUV loop changes during one of the flares matches an asymmetry in the photospheric magnetic changes associated with that flare. The observations are discussed in terms of the well-known tether-cutting and breakout flare initiation models.

  4. High-resolution observations of active region moss and its dynamics

    Morton, R. J.; McLaughlin, J. A., E-mail: richard.morton@northumbria.ac.uk [Department of Mathematics and Information Sciences, Northumbria University, Newcastle Upon Tyne, NE1 8ST (United Kingdom)

    2014-07-10

    The High Resolution Coronal Imager has provided the sharpest view of the EUV corona to date. In this paper, we exploit its impressive resolving power to provide the first analysis of the fine-scale structure of moss in an active region. The data reveal that the moss is made up of a collection of fine threads that have widths with a mean and standard deviation of 440 ± 190 km (FWHM). The brightest moss emission is located at the visible head of the fine-scale structure and the fine structure appears to extend into the lower solar atmosphere. The emission decreases along the features, implying that the lower sections are most likely dominated by cooler transition region plasma. These threads appear to be the cool, lower legs of the hot loops. In addition, the increased resolution allows for the first direct observation of physical displacements of the moss fine structure in a direction transverse to its central axis. Some of these transverse displacements demonstrate periodic behavior, which we interpret as a signature of kink (Alfvénic) waves. Measurements of the properties of the transverse motions are made and the wave motions have means and standard deviations of 55 ± 37 km for the transverse displacement amplitude, 77 ± 33 s for the period, and 4.7 ± 2.5 km s{sup –1} for the velocity amplitude. The presence of waves in the transition region of hot loops could have important implications for the heating of active regions.

  5. Regional National Cooperative Observer

    National Oceanic and Atmospheric Administration, Department of Commerce — NOAA publication dedicated to issues, news and recognition of observers in the National Weather Service Cooperative Observer program. Issues published regionally...

  6. Anti-parallel EUV flows observed along active region filament threads with Hi-C

    Alexander, Caroline E; Regnier, Stephane; Cirtain, Jonathan; Winebarger, Amy R; Golub, Leon; Kobayashi, Ken; Platt, Simon; Mitchell, Nick; Korreck, Kelly; DePontieu, Bart; DeForest, Craig; Weber, Mark; Title, Alan; Kuzin, Sergey

    2013-01-01

    Plasma flows within prominences/filaments have been observed for many years and hold valuable clues concerning the mass and energy balance within these structures. Previous observations of these flows primarily come from H-alpha and cool EUV lines (e.g., 304A) where estimates of the size of the prominence threads has been limited by the resolution of the available instrumentation. Evidence of `counter-steaming' flows has previously been inferred from these cool plasma observations but now, for the first time, these flows have been directly imaged along fundamental filament threads within the million degree corona (at 193A). In this work we present observations of an active region filament observed with Hi-C that exhibits anti-parallel flows along adjacent filament threads. Complementary data from SDO/AIA and HMI are presented. The ultra-high spatial and temporal resolution of Hi-C allow the anti-parallel flow velocities to be measured (70-80 km/s) and gives an indication of the resolvable thickness of the ind...

  7. TEMPERATURE DISTRIBUTION OF A NON-FLARING ACTIVE REGION FROM SIMULTANEOUS HINODE XRT AND EIS OBSERVATIONS

    We analyze coordinated Hinode X-ray Telescope (XRT) and Extreme Ultraviolet Imaging Spectrometer (EIS) observations of a non-flaring active region to investigate the thermal properties of coronal plasma taking advantage of the complementary diagnostics provided by the two instruments. In particular, we want to explore the presence of hot plasma in non-flaring regions. Independent temperature analyses from the XRT multi-filter data set, and the EIS spectra, including the instrument entire wavelength range, provide a cross-check of the different temperature diagnostics techniques applicable to broadband and spectral data, respectively, and insights into cross-calibration of the two instruments. The emission measure distributions, (EM(T)), we derive from the two data sets have similar width and peak temperature, but show a systematic shift of the absolute values, the EIS (EM(T)) being smaller than the XRT (EM(T)) by approximately a factor two. We explore possible causes of this discrepancy, and we discuss the influence of the assumptions for the plasma element abundances. Specifically, we find that the disagreement between the results from the two instruments is significantly mitigated by assuming chemical composition closer to the solar photospheric composition rather than the often adopted 'coronal' composition. We find that the data do not provide conclusive evidence on the high temperature (log T(K) ∼> 6.5) tail of the plasma temperature distribution, however, suggesting its presence to a level in agreement with recent findings for other non-flaring regions.

  8. Observations of photospheric magnetic fields and shear flows in flaring active regions

    Horizontal flows in the photosphere and subsurface convection zone move the footpoints of coronal magnetic field lines. Magnetic energy to power flares can be stored in the corona if the flows drive the fields far from the potential configuration. Videodisk movies were shown with 0.5 to 1 arcsecond resolution of the following simultaneous observations: green continuum, longitudinal magnetogram, Fe I 5576 A line center (mid-photosphere), H alpha wings, and H alpha line center. The movies show a 90 x 90 arcsecond field of view of an active region at S29, W11. When viewed at speeds of a few thousand times real-time, the photospheric movies clearly show the active region fields being distorted by a remarkable combination of systematic flows and small eruptions of new flux. Magnetic bipoles are emerging over a large area, and the polarities are systematically flowing apart. The horizontal flows were mapped in detail from the continuum movies, and these may be used to predict the future evolution of the region. The horizontal flows are not discernable in H alpha. The H alpha movies strongly suggest reconnection processes in the fibrils joining opposite polarities. When viewed in combination with the magnetic movies, the cause for this evolution is apparent: opposite polarity fields collide and partially cancel, and the fibrils reconnect above the surface. This type of reconnection, driven by subphotospheric flows, complicates the chromospheric and coronal fields, causing visible braiding and twisting of the fibrils. Some of the transient emission events in the fibrils and adjacent plage may also be related

  9. Temperature distribution of a non-flaring active region from simultaneous Hinode XRT and EIS observations

    Testa, Paola; Landi, Enrico; DeLuca, Ed; Kashyap, Vinay

    2010-01-01

    We analyze coordinated Hinode XRT and EIS observations of a non-flaring active region to investigate the thermal properties of coronal plasma taking advantage of the complementary diagnostics provided by the two instruments. In particular we want to explore the presence of hot plasma in non-flaring regions. Independent temperature analyses from the XRT multi-filter dataset, and the EIS spectra, including the instrument entire wavelength range, provide a cross-check of the different temperature diagnostics techniques applicable to broad-band and spectral data respectively, and insights into cross-calibration of the two instruments. The emission measure distribution, EM(T), we derive from the two datasets have similar width and peak temperature, but show a systematic shift of the absolute values, the EIS EM(T) being smaller than XRT EM(T) by approximately a factor 2. We explore possible causes of this discrepancy, and we discuss the influence of the assumptions for the plasma element abundances. Specifically, w...

  10. Photospheric and Coronal Observations of Abrupt Magnetic Restructuring in Flaring Active Regions

    Petrie, G. J. D.

    2015-12-01

    The Lorentz force changes associated with strong photospheric fields in large structures within active regions can be estimated from time series of Solar Dynamics Observatory (SDO) Helioseismic and Magnetic Imager (HMI) vector magnetograms. The major, most organized changes tend to occur close to the centers of flaring regions, near the main neutral line and/or in twisted sunspots. Fields close to the neutral line tend to collapse downward and inward, consistent with compression rather than rotation of the vector field. In sunspots the twist (or azimuthal component around the sunspot axis) tends to decrease. In a limited number of cases particularly well-observed by the Atmospheric Imaging Assembly (AIA) on SDO and the Extreme Ultraviolet Imager (EUVI) on the Solar TErrestrial RElations Observatory (STEREO), the evolution of the photospheric magnetic vector field can be related to changes in coronal magnetic structure to provide a coherent description of the magnetic changes during the different phases of a flare. This work was supported by NASA grant NNX14AE05G.

  11. Ultra-Hot Plasma in Active Regions Observed by the Extreme-ultraviolet Imaging Spectrometer on Hinode

    Doschek, G. A.; Warren, H. P.; Feldman, U.

    2008-05-01

    The Extreme-ultraviolet Imaging Spectrometer (EIS) on the Hinode spacecraft obtains high resolution spectra of the solar atmosphere in two wavelength ranges: 170 - 210 and 250 — 290 Angstroms. These wavelength regions contain a wealth of emission lines covering temperature regions from the chromosphere/transition region (e.g., He II, Si VII) up to soft X-ray flare temperatures (Fe XXIII, Fe XXIV). EIS can obtain line profiles and intensities for the spectral lines in these wavelength regions. Of particular interest for understanding coronal heating is a line of Ca XVII, formed near a temperature of 6 MK. This line is blended with lines of Fe XI and O V. However, by using unblended lines of these ions, the Ca XVII line can be deconvolved from the blended emission. EIS has obtained many raster observations of active regions by stepping the slit in small increments across the active region, producing monochromatic images of the active region. The Ca XVII blend has been included in many of these rasters. In this paper we discuss the appearance and frequency of 6 MK plasma in active regions in the absence of strong flaring activity. This temperature region is not well-observed by normal incidence imaging spectrometers and therefore the EIS data shed light on higher temperature areas of active regions than normally available from imaging instruments alone. We discuss how to deconvolve the blend and show examples of 6 MK plasma emission in several active regions.

  12. Characteristics of Anemone Active Regions Appearing in Coronal Holes Observed with {\\it Yohkoh} Soft X-ray Telescope

    Asai, Ayumi; Shibata, Kazunari; Hara, Hirohisa; Nitta, Nariaki V.

    2008-01-01

    Coronal structure of active regions appearing in coronal holes is studied by using the data obtained with the Soft X-Ray Telescope (SXT) aboard {\\it Yohkoh} from 1991 November to 1993 March. The following characteristics are found; Many of active regions appearing in coronal holes show a structure that looks like a ``sea-anemone''. Such active regions are called {\\it anemone ARs}. About one-forth of all active regions that were observed with SXT from their births showed the anemone structure....

  13. Light Bridge in a Developing Active Region. I. Observation of Light Bridge and its Dynamic Activity Phenomena

    Toriumi, Shin; Cheung, Mark C M

    2015-01-01

    Light bridges, the bright structures that divide the umbra of sunspots and pores into smaller pieces, are known to produce wide variety of activity events in solar active regions (ARs). It is also known that the light bridges appear in the assembling process of nascent sunspots. The ultimate goal of this series of papers is to reveal the nature of light bridges in developing ARs and the occurrence of activity events associated with the light bridge structures from both observational and numerical approaches. In this first paper, exploiting the observational data obtained by Hinode, IRIS, and Solar Dynamics Observatory (SDO), we investigate the detailed structure of the light bridge in NOAA AR 11974 and its dynamic activity phenomena. As a result, we find that the light bridge has a weak, horizontal magnetic field, which is transported from the interior by large-scale convective upflow and is surrounded by strong, vertical fields of adjacent pores. In the chromosphere above the bridge, a transient brightening ...

  14. The 3D structure of an active region filament as extrapolated from photospheric and chromospheric observations

    Chaouche, L Yelles; Pillet, V Martínez; Moreno-Insertis, F

    2012-01-01

    The 3D structure of an active region (AR) filament is studied using nonlinear force-free field (NLFFF) extrapolations based on simultaneous observations at a photospheric and a chromospheric height. To that end, we used the Si I 10827 \\AA\\ line and the He I 10830 \\AA\\ triplet obtained with the Tenerife Infrared Polarimeter (TIP) at the VTT (Tenerife). The two extrapolations have been carried out independently from each other and their respective spatial domains overlap in a considerable height range. This opens up new possibilities for diagnostics in addition to the usual ones obtained through a single extrapolation from, typically, a photospheric layer. Among those possibilities, this method allows the determination of an average formation height of the He I 10830 \\AA\\ signal of \\approx 2 Mm above the surface of the sun. It allows, as well, to cross-check the obtained 3D magnetic structures in view of verifying a possible deviation from the force- free condition especially at the photosphere. The extrapolati...

  15. Functional photoacoustic imaging to observe regional brain activation induced by cocaine hydrochloride

    Jo, Janggun; Yang, Xinmai

    2011-09-01

    Photoacoustic microscopy (PAM) was used to detect small animal brain activation in response to drug abuse. Cocaine hydrochloride in saline solution was injected into the blood stream of Sprague Dawley rats through tail veins. The rat brain functional change in response to the injection of drug was then monitored by the PAM technique. Images in the coronal view of the rat brain at the locations of 1.2 and 3.4 mm posterior to bregma were obtained. The resulted photoacoustic (PA) images showed the regional changes in the blood volume. Additionally, the regional changes in blood oxygenation were also presented. The results demonstrated that PA imaging is capable of monitoring regional hemodynamic changes induced by drug abuse.

  16. On Asymmetry of Magnetic Helicity in Emerging Active Regions: High Resolution Observations

    Tian, Lirong; Démoulin, Pascal; Alexander, David; Zhu, Chunming

    2011-01-01

    We employ the DAVE (differential affine velocity estimator, Schuck 2005; 2006) tracking technique on a time series of MDI/1m high spatial resolution line- of-sight magnetograms to measure the photospheric flow velocity for three newly emerging bipolar active regions. We separately calculate the magnetic helicity injection rate of the leading and following polarities to confirm or refute the magnetic helicity asymmetry, found by Tian & Alexander (2009) using MDI/96m low spatial resolution magn...

  17. Characteristics of Anemone Active Regions Appearing in Coronal Holes Observed with {\\it Yohkoh} Soft X-ray Telescope

    Asai, Ayumi; Hara, Hirohisa; Nitta, Nariaki V

    2008-01-01

    Coronal structure of active regions appearing in coronal holes is studied by using the data obtained with the Soft X-Ray Telescope (SXT) aboard {\\it Yohkoh} from 1991 November to 1993 March. The following characteristics are found; Many of active regions appearing in coronal holes show a structure that looks like a ``sea-anemone''. Such active regions are called {\\it anemone ARs}. About one-forth of all active regions that were observed with SXT from their births showed the anemone structure. For almost all the anemone ARs, the order of magnetic polarities is consistent with the Hale-Nicholson's polarity law. These anemone ARs also showed more or less east-west asymmetry in X-ray intensity distribution, such that the following (eastern) part of the ARs is brighter than its preceding (western) part. This, as well as the anemone shape itself, is consistent with the magnetic polarity distribution around the anemone ARs. These observations also suggest that an active region appearing in coronal holes has simpler ...

  18. Radio Observations of the Star Formation Activities in the NGC 2024 FIR 4 Region

    Choi, Minho; Lee, Jeong-Eun

    2015-01-01

    Star formation activities in the NGC 2024 FIR 4 region were studied by imaging centimeter continuum sources and water maser sources using several archival data sets from the Very Large Array. The continuum source VLA 9 is elongated in the northwest-southeast direction, consistent with the FIR 4 bipolar outflow axis, and has a flat spectrum in the 6.2-3.6 cm interval. The three water maser spots associated with FIR 4 are also distributed along the outflow axis. One of the spots is located close to VLA 9, and another one is close to an X-ray source. Examinations of the positions of compact objects in this region suggest that the FIR 4 cloud core contains a single low-mass protostar. VLA 9 is the best indicator of the protostellar position. VLA 9 may be a radio thermal jet driven by this protostar, and it is unlikely that FIR 4 contains a high-mass young stellar object (YSO). A methanol 6.7 GHz maser source is located close to VLA 9, at a distance of about 100 AU. The FIR 4 protostar must be responsible for the ...

  19. The quiescent chromospheres and transition regions of active dwarf stars - What are we learning from recent observations and models?

    Linsky, J. L.

    1983-01-01

    Progress in understanding active dwarf stars based on recent IUE, Einstein, and ground-based observations is reviewed. The extent of magnetic field control over nonflare phenomena in active dwarf stars is considered, and the spatial homogeneity and time variability of active dwarf atmospheres is discussed. The possibility that solar like flux tubes can explain enhanced heating in active dwarf stars in examined, and the roles of systematic flows in active dwarf star atmospheres are considered. The relation between heating rates in different layers of active dwarf stars is summarized, and the mechanism of chromosphere and transition region heating in these stars are discussed. The results of one-component and two-component models of active dwarf stars are addressed.

  20. Pervasive faint Fe XIX emission from a solar active region observed with EUNIS-13: Evidence for nanoflare heating

    Brosius, Jeffrey W. [Catholic University of America at NASA Goddard Space Flight Center, Solar Physics Laboratory, Code 671, Greenbelt, MD 20771 (United States); Daw, Adrian N. [NASA Goddard Space Flight Center, Solar Physics Laboratory, Code 671, Greenbelt, MD 20771 (United States); Rabin, D. M., E-mail: Jeffrey.W.Brosius@nasa.gov [NASA Goddard Space Flight Center, Heliophysics Science Division, Code 670, Greenbelt, MD 20771 (United States)

    2014-08-01

    We present spatially resolved EUV spectroscopic measurements of pervasive, faint Fe XIX 592.2 Å line emission in an active region observed during the 2013 April 23 flight of the Extreme Ultraviolet Normal Incidence Spectrograph (EUNIS-13) sounding rocket instrument. With cooled detectors, high sensitivity, and high spectral resolution, EUNIS-13 resolves the lines of Fe XIX at 592.2 Å (formed at temperature T ≈ 8.9 MK) and Fe XII at 592.6 Å (T ≈ 1.6 MK). The Fe XIX line emission, observed over an area in excess of 4920 arcsec{sup 2} (2.58 × 10{sup 9} km{sup 2}, more than 60% of the active region), provides strong evidence for the nanoflare heating model of the solar corona. No GOES events occurred in the region less than 2 hr before the rocket flight, but a microflare was observed north and east of the region with RHESSI and EUNIS during the flight. The absence of significant upward velocities anywhere in the region, particularly the microflare, indicates that the pervasive Fe XIX emission is not propelled outward from the microflare site, but is most likely attributed to localized heating (not necessarily due to reconnection) consistent with the nanoflare heating model of the solar corona. Assuming ionization equilibrium we estimate Fe XIX/Fe XII emission measure ratios of ∼0.076 just outside the AR core and ∼0.59 in the core.

  1. Pervasive faint Fe XIX emission from a solar active region observed with EUNIS-13: Evidence for nanoflare heating

    We present spatially resolved EUV spectroscopic measurements of pervasive, faint Fe XIX 592.2 Å line emission in an active region observed during the 2013 April 23 flight of the Extreme Ultraviolet Normal Incidence Spectrograph (EUNIS-13) sounding rocket instrument. With cooled detectors, high sensitivity, and high spectral resolution, EUNIS-13 resolves the lines of Fe XIX at 592.2 Å (formed at temperature T ≈ 8.9 MK) and Fe XII at 592.6 Å (T ≈ 1.6 MK). The Fe XIX line emission, observed over an area in excess of 4920 arcsec2 (2.58 × 109 km2, more than 60% of the active region), provides strong evidence for the nanoflare heating model of the solar corona. No GOES events occurred in the region less than 2 hr before the rocket flight, but a microflare was observed north and east of the region with RHESSI and EUNIS during the flight. The absence of significant upward velocities anywhere in the region, particularly the microflare, indicates that the pervasive Fe XIX emission is not propelled outward from the microflare site, but is most likely attributed to localized heating (not necessarily due to reconnection) consistent with the nanoflare heating model of the solar corona. Assuming ionization equilibrium we estimate Fe XIX/Fe XII emission measure ratios of ∼0.076 just outside the AR core and ∼0.59 in the core.

  2. Active region fine structure observed at 0.08 arcsec resolution

    Schlichenmaier, R; Hoch, S; Soltau, D; Berkefeld, T; Schmidt, D; Schmidt, W; Denker, C; Balthasar, H; Hofmann, A; Strassmeier, K G; Staude, J; Feller, A; Lagg, A; Solanki, S K; Collados, M; Sigwarth, M; Volkmer, R; Waldmann, T; Kneer, F; Nicklas, H; Sobotka, M

    2016-01-01

    The various mechanisms of magneto-convective energy transport determines the structure of sunspots and active regions. We characterise the appearance of light bridges and other fine structure details and elaborate on their magneto-convective nature. We present speckle-reconstructed images taken with the broad band imager at the 1.5 m GREGOR telescope in the 486nm and 589nm bands. We estimate the spatial resolution from the noise characteristics of the image bursts and obtain 0.08" at 589nm. We describe structure details in individual best images as well as the temporal evolution of selected features. We find branched dark lanes extending along thin (~1") light bridges in sunspots at various heliocentric angles. In thick (~2") light bridges the branches are disconnected from the central lane and have a `Y' shape with a bright grain toward the umbra. The images reveal that light bridges exist on varying intensity levels and that their small-scale features evolve on time scales of minutes. Faint light bridges sh...

  3. High resolution ALMA observations of dense molecular medium in the central regions of active galaxies

    Kohno, Kotaro; Taniguchi, Akio; Izumi, Takuma; Tosaki, Tomoka

    2016-01-01

    In the central regions of active galaxies, dense molecular medium are exposed to various types of radiation and energy injections, such as UV, X-ray, cosmic ray, and shock dissipation. With the rapid progress of chemical models and implementation of new-generation mm/submm interferometry, we are now able to use molecules as powerful diagnostics of the physical and chemical processes in galaxies. Here we give a brief overview on the recent ALMA results to demonstrate how molecules can reveal underlying physical and chemical processes in galaxies. First, new detections of Galactic molecular absorption systems with elevated HCO/H$^{13}$CO$^+$ column density ratios are reported, indicating that these molecular media are irradiated by intense UV fields. Second, we discuss the spatial distributions of various types of shock tracers including HNCO, CH$_3$OH and SiO in NGC 253 and NGC 1068. Lastly, we provide an overview of proposed diagnostic methods of nuclear energy sources using ALMA, with an emphasis on the syne...

  4. Volcanic activity observed from continuous seismic records in the region of the Klyuchevskoy group of volcanoes

    Shapiro, N.; Droznin, D.; Droznina, S.; Senyukov, S.; Chebrov, V.; Gordeev, E.; Frank, W.

    2015-12-01

    We analyze continuous seismic records from 18 permanent stations operated in vicinity of the Klyuchevskoy group of volcanos (Kamchatka, Russia) during the period between 2009 and 2014. We explore the stability of the inter-station cross-correlation to detect different periods of sustained emission from seismic energy. The main idea of this approach is that cross-correlation waveforms computed from a wavefield emitted by a seismic source from a fixed position remain stable during the period when this source is acting. The detected periods of seismic emission correspond to different episodes of activity of volcanoes: Klyuchevskoy, Tolbachik, Shiveluch, and Kizimen. For Klyuchevskoy and Tolbachik whose recent eruptions are mostly effusive, the detected seismic signals correspond to typical volcanic tremor, likely caused by degassing processes. For Shiveluch and Kizimen producing more silicic lavas, the observed seismic emission often consists of many repetitive long period (LP) seismic events that might be related to the extrusion of viscous magmas. We develop an approach for automatic detection of these individual LP events in order to characterize variations of their size and recurrence in time.

  5. On the line profile changes observed during the X2.2 class flare in the active region NOAA 11158

    The solar active region NOAA 11158 produced a series of flares during its passage through the solar disk. The first major flare (of class X2.2) of the current solar cycle occurred in this active region on 2011 February 15 around 01:50 UT. We have analyzed the Dopplergrams and magnetograms obtained by the Helioseismic and Magnetic Imager (HMI) instrument onboard Solar Dynamics Observatory to examine the photospheric velocity and magnetic field changes associated with this flare. The HMI instrument provides high-quality Doppler and magnetic maps of the solar disk with 0.5″ spatial scale at a cadence of 45 s along with imaging spectroscopy. We have identified five locations of velocity transients in the active region during the flare. These transient velocity signals are located in and around the flare ribbons as observed by Hinode in the Ca II H wavelength and the footpoints of hard X-ray enhancement are in the energy range 12–25 keV from RHESSI. The changes in shape and width of two circular polarization states have been observed at the time of transients in three out of five locations. Forward modeling of the line profiles shows that the change in atmospheric parameters such as magnetic field strength, Doppler velocity and source function could explain the observed changes in the line profiles with respect to the pre-flare condition

  6. Analysis of X-ray observations of the 15 June 1973 flare in active region NOAA 131

    Observations and analyses of the 1B/M3 flare of 15 June, 1973 in active region NOAA 131 (McMath 12379) are presented. The X-ray observations, consisting of broadband photographs and proportional counter data from the Skylab/ATM NASA-MSFC/Aerospace S-056 experiment, are used to infer temperatures, emission measures, and densities for the flaring plasma. The peak temperature from the spatially resolved photographs is 25x106 K, while the temperature from the full-disk proportional counter data is approximately 15x106 K. The density is 3x1010 cm-3. The X-ray flare emission appears to come primarily from two low-lying curvilinear features lying perpendicular to and centered on the line where the photospheric longitudinal magnetic field is zero. Similarities in the preflare and postflare X-ray emission patterns indicate that no large-scale relaxation of the coronal magnetic configuration was observed. Also discussed are Hα and magnetic field observations of the flare and the active region. Finally, results of numerical calculations, including thermal conduction, radiative loss and chromospheric evaporation, are in qualitative agreement with the decay phase observations. (Auth.)

  7. The quiescent chromospheres and transition regions of active dwarf stars: what are we learning from recent observations and models

    The rapid progress in understanding active dwarf stars, which has been stimulated by recent IUE, Einstein and ground-based observations, is reviewed. Active phenomena in late-type dwarf stars are seen as somehow a direct consequence of strong magnetic fields. The nonflare phenomena in the chromosphere and transition regions of these stars are discussed, while some suggestions are given about the way in which magnetic fields control these phenomena. Especially, the review deals with a description and comparison of those activities which are similar in active and quiescent dwarf stars and summarizes the various roles which magnetic fields likely play in modifying the chromospheres and transition regions of active stars. Successively, the following subjects are discussed: the basic structure of the stars, the enhanced heating and solar-like flux tubes, the consequences of plasma flows, heating rates in different layers, heating mechanism of chromosphere and transition region, semi-empirical models. The author finishes with some suggestions for future work. (G.J.P.)

  8. Anti-parallel EUV Flows Observed along Active Region Filament Threads with Hi-C

    Alexander, Caroline E.; Walsh, Robert W.; Régnier, Stéphane; Cirtain, Jonathan; Winebarger, Amy R.; Golub, Leon; Kobayashi, Ken; Platt, Simon; Mitchell, Nick; Korreck, Kelly; DePontieu, Bart; DeForest, Craig; Weber, Mark; Title, Alan; Kuzin, Sergey

    2013-09-01

    Plasma flows within prominences/filaments have been observed for many years and hold valuable clues concerning the mass and energy balance within these structures. Previous observations of these flows primarily come from Hα and cool extreme-ultraviolet (EUV) lines (e.g., 304 Å) where estimates of the size of the prominence threads has been limited by the resolution of the available instrumentation. Evidence of "counter-steaming" flows has previously been inferred from these cool plasma observations, but now, for the first time, these flows have been directly imaged along fundamental filament threads within the million degree corona (at 193 Å). In this work, we present observations of an AR filament observed with the High-resolution Coronal Imager (Hi-C) that exhibits anti-parallel flows along adjacent filament threads. Complementary data from the Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) and Helioseismic and Magnetic Imager are presented. The ultra-high spatial and temporal resolution of Hi-C allow the anti-parallel flow velocities to be measured (70-80 km s-1) and gives an indication of the resolvable thickness of the individual strands (0.''8 ± 0.''1). The temperature of the plasma flows was estimated to be log T (K) = 5.45 ± 0.10 using Emission Measure loci analysis. We find that SDO/AIA cannot clearly observe these anti-parallel flows or measure their velocity or thread width due to its larger pixel size. We suggest that anti-parallel/counter-streaming flows are likely commonplace within all filaments and are currently not observed in EUV due to current instrument spatial resolution.

  9. ANTI-PARALLEL EUV FLOWS OBSERVED ALONG ACTIVE REGION FILAMENT THREADS WITH HI-C

    Plasma flows within prominences/filaments have been observed for many years and hold valuable clues concerning the mass and energy balance within these structures. Previous observations of these flows primarily come from Hα and cool extreme-ultraviolet (EUV) lines (e.g., 304 Å) where estimates of the size of the prominence threads has been limited by the resolution of the available instrumentation. Evidence of 'counter-steaming' flows has previously been inferred from these cool plasma observations, but now, for the first time, these flows have been directly imaged along fundamental filament threads within the million degree corona (at 193 Å). In this work, we present observations of an AR filament observed with the High-resolution Coronal Imager (Hi-C) that exhibits anti-parallel flows along adjacent filament threads. Complementary data from the Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) and Helioseismic and Magnetic Imager are presented. The ultra-high spatial and temporal resolution of Hi-C allow the anti-parallel flow velocities to be measured (70-80 km s–1) and gives an indication of the resolvable thickness of the individual strands (0.''8 ± 0.''1). The temperature of the plasma flows was estimated to be log T (K) = 5.45 ± 0.10 using Emission Measure loci analysis. We find that SDO/AIA cannot clearly observe these anti-parallel flows or measure their velocity or thread width due to its larger pixel size. We suggest that anti-parallel/counter-streaming flows are likely commonplace within all filaments and are currently not observed in EUV due to current instrument spatial resolution

  10. Flows in and around active region NOAA12118 observed with the GREGOR solar telescope and SDO/HMI

    Verma, M; Balthasar, H; Kuckein, C; Manrique, S J González; Sobotka, M; González, N Bello; Hoch, S; Diercke, A; Kummerow, P; Berkefeld, T; Collados, M; Feller, A; Hofmann, A; Kneer, F; Lagg, A; Löhner-Böttcher, J; Nicklas, H; Yabar, A Pastor; Schlichenmaier, R; Schmidt, D; Schmidt, W; Schubert, M; Sigwarth, M; Solanki, S K; Soltau, D; Staude, J; Strassmeier, K G; Volkmer, R; von der Lühe, O; Waldmann, T

    2016-01-01

    Accurate measurements of magnetic and velocity fields in and around solar active regions are key to unlocking the mysteries of the formation and the decay of sunspots. High spatial resolution image and spectral sequences with a high cadence obtained with the GREGOR solar telescope give us an opportunity to scrutinize 3-D flow fields with local correlation tracking and imaging spectroscopy. We present GREGOR early science data acquired in 2014 July - August with the GREGOR Fabry-P\\'erot Interferometer and the Blue Imaging Channel. Time-series of blue continuum (? 450.6 nm) images of the small active region NOAA 12118 were restored with the speckle masking technique to derive horizontal proper motions and to track the evolution of morphological changes. In addition, high-resolution observations are discussed in the context of synoptic data from the Solar Dynamics Observatory.

  11. Constraining Hot Plasma in a Non-flaring Solar Active Region with FOXSI Hard X-ray Observations

    Ishikawa, Shin-nosuke; Christe, Steven; Ishibashi, Kazunori; Brooks, David H; Williams, David R; Shimojo, Masumi; Sako, Nobuharu; Krucker, Sam

    2015-01-01

    We present new constraints on the high-temperature emission measure of a non-flaring solar active region using observations from the recently flown Focusing Optics X-ray Solar Imager sounding rocket payload. FOXSI has performed the first focused hard X-ray (HXR) observation of the Sun in its first successful flight on 2012 November 2. Focusing optics, combined with small strip detectors, enable high-sensitivity observations with respect to previous indirect imagers. This capability, along with the sensitivity of the HXR regime to high-temperature emission, offers the potential to better characterize high-temperature plasma in the corona as predicted by nanoflare heating models. We present a joint analysis of the differential emission measure (DEM) of active region 11602 using coordinated observations by FOXSI, Hinode/XRT and Hinode/EIS. The Hinode-derived DEM predicts significant emission measure between 1 MK and 3 MK, with a peak in the DEM predicted at 2.0-2.5 MK. The combined XRT and EIS DEM also shows emi...

  12. Kelvin--Helmholtz instability in an active region jet observed with \\emph{Hinode}

    Zhelyazkov, I; Srivastava, A K

    2015-01-01

    Over past ten years a variety of jet-like phenomena were detected in the solar atmosphere, including plasma ejections over a range of coronal temperatures being observed as extreme ultraviolet (EUV) and X-ray jets. We study the possibility for the development of Kelvin--Helmholtz (KH) instability of transverse magnetohydrodynamic (MHD) waves traveling along an EUV jet situated on the west side of NOAA AR 10938 and observed by three instruments on board Hinode on 2007 January 15/16 (Chifor et al., Astron. Astrophys.481, L57 (2008)). The jet was observed around LogT_e = 6.2 with up-flow velocities exceeded 150 km/s. Using Fe XII lambda186 and lambda195 line ratios, the measured densities were found to be above LogN_e = 11. We have modeled that EUV jet as a vertically moving magnetic flux tube (untwisted and weakly twisted) and have studied the propagation characteristics of the kink (m=1) mode and the higher m modes with azimuthal mode numbers m=2,3,4. It turns out that all these MHD waves can become unstable a...

  13. Helioseismic Survey of the Near-surface Flows Around the Largest Active Regions with SDO-HMI Observations

    Braun, Douglas; DeGrave, Kyle

    2016-05-01

    We report on the properties of the near-surface flows, determined from helioseismic holography applied to HMI Dopplergrams, of approximately 250 of the largest active regions observed during the first five years of SDO observations. A recent study which examined the potential association of flows with the production of solar flares in this survey has recently been published (Braun 2016, ApJ 819, 106). We discuss here additional findings on general flow properties of the regions in our survey derived from ensemble averages of the flows. This averaging eliminates the dominating effect of the supergranulation signal, and shows outflows from sunspots surrounded by compact inflows. The properties of these flows are described. The potential use of these measurements for determining the contribution of active-region related flows to global dynamics (including differential rotation and meridional circulation) and flux-transport models is discussed. This work is supported by the NSF Solar Terrestrial Program through grant AGS-1127327 and by the NASA Heliophysics Division through NNH12CF68C and NNX16AG88G.

  14. High spatial resolution VAULT H-Lyα observations and multiwavelength analysis of an active region filament

    Vial, J.-C.; Olivier, K.; Philippon, A. A.; Vourlidas, A.; Yurchyshyn, V.

    2012-05-01

    Context. The search for the fine structure of prominences has received considerable new attention thanks to the Swedish Solar Telescope (SST) Hα pictures that provide an unsurpassed spatial resolution. Recently, it has been shown that the filaments' coronal environment, at least for quiescent filaments, is perturbed by either cool absorbing material (in the EUV) or an "emissivity blocking" (actually a lack of transition region and coronal material). Aims: The aim is to assess the fine structure in an active region filament and to determine the nature of the EUV absorption or lack of emission phenomena, using the very optically thick line H-Lyα, formed at a temperature higher than Hα. Methods: We performed a multiwavelength study where high-resolution imaging in the H-Lyα line (VAULT) was analysed and compared with observations of an active region filament in Hα (BBSO) and EUV lines (EIT and TRACE). Results: As for the SST data, small-scale structures were detected at a typical scale of about one to two arcseconds with, for some cuts, an indication of fine scales down to 0.4 arcsec in the optically thick H-Lyα line. The filament intensity relative to the intensity of the (active) region it is embedded in is about 0.2 in H-Lyα. This ratio (Lymanα ratio intensity or "LRI") is the lowest value compared to other lines, e.g. Hα. The filament environment was also investigated and evidence of an UV extension was found. The comparison of spatial cuts in different lines across the filament shows evidence of strong absorption, and consequently of cool plasma on one side of the filament, but not on the other (that side is obscured by the filament itself). Conclusions: The absence of very fine structure in H-Lyα compared to Hα is explained by the formation temperature of the H-Lyα line (~20 000 K), where the transition regions of the thin threads begin to merge. From the detection of H-Lyα absorption on the observable side of the filament side, we derive the

  15. RECONSTRUCTING THE SUBSURFACE THREE-DIMENSIONAL MAGNETIC STRUCTURE OF A SOLAR ACTIVE REGION USING SDO/HMI OBSERVATIONS

    A solar active region (AR) is a three-dimensional (3D) magnetic structure formed in the convection zone, whose property is fundamentally important for determining the coronal structure and solar activity when emerged. However, our knowledge of the detailed 3D structure prior to its emergence is rather poor, largely limited by the low cadence and sensitivity of previous instruments. Here, using the 45 s high-cadence observations from the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory, we are able for the first time to reconstruct a 3D data cube and infer the detailed subsurface magnetic structure of NOAA AR 11158, and to characterize its magnetic connectivity and topology. This task is accomplished with the aid of the image-stacking method and advanced 3D visualization. We find that the AR consists of two major bipoles or four major polarities. Each polarity in 3D shows interesting tree-like structure, i.e., while the root of the polarity appears as a single tree-trunk-like tube, the top of the polarity has multiple branches consisting of smaller and thinner flux tubes which connect to the branches of the opposite polarity that is similarly fragmented. The roots of the four polarities align well along a straight line, while the top branches are slightly non-coplanar. Our observations suggest that an active region, even appearing highly complicated on the surface, may originate from a simple straight flux tube that undergoes both horizontal and vertical bifurcation processes during its rise through the convection zone.

  16. Determining inclinations of active galactic nuclei via their narrow-line region kinematics. II. Correlation with observed properties

    Active galactic nuclei (AGNs) are axisymmetric systems to first order; their observed properties are likely strong functions of inclination with respect to our line of sight, yet the specific inclinations of all but a few AGNs are generally unknown. By determining the inclinations and geometries of nearby Seyfert galaxies using the kinematics of their narrow-line regions (NLRs) and comparing them with observed properties, we find strong correlations between inclination and total hydrogen column density, infrared color, and Hβ FWHM. These correlations provide evidence that the orientation of AGNs with respect to our line of sight affects how we perceive them beyond the Seyfert 1/2 dichotomy. They can also be used to constrain three-dimensional models of AGN components such as the broad-line region and torus. Additionally, we find weak correlations between AGN luminosity and several modeled NLR parameters, which suggests that the NLR geometry and kinematics are dependent to some degree on the AGN's radiation field.

  17. CORONAL HEATING BY THE INTERACTION BETWEEN EMERGING ACTIVE REGIONS AND THE QUIET SUN OBSERVED BY THE SOLAR DYNAMICS OBSERVATORY

    The question of what heats the solar corona remains one of the most important puzzles in solar physics and astrophysics. Here we report Solar Dynamics Observatory Atmospheric Imaging Assembly observations of coronal heating by the interaction between emerging active regions (EARs) and the surrounding quiet Sun (QS). The EARs continuously interact with the surrounding QS, resulting in dark ribbons which appear at the boundary of the EARs and the QS. The dark ribbons visible in extreme-ultraviolet wavelengths propagate away from the EARs with speeds of a few km s−1. The regions swept by the dark ribbons are brightening afterward, with the mean temperature increasing by one quarter. The observational findings demonstrate that uninterrupted magnetic reconnection between EARs and the QS occurs. When the EARs develop, the reconnection continues. The dark ribbons may be the track of the interface between the reconnected magnetic fields and the undisturbed QS’s fields. The propagating speed of the dark ribbons reflects the reconnection rate and is consistent with our numerical simulation. A long-term coronal heating which occurs in turn from nearby the EARs to far away from the EARs is proposed

  18. Analysis of peculiar penumbral flows observed in the active region NOAA 10930 during a major solar flare

    It is believed that the high energetic particles and tremendous amount of energy released during the flares can induce velocity oscillations in the Sun. Using the Dopplergrams obtained by Global Oscillation Network Group (GONG) telescope, we analyze the velocity flows in the active region NOAA 10930 during a major flare (of class X3.4) that occurred on 13 December 2006. We observe peculiar evolution of velocity flows in some localized portions of the penumbra of this active region during the flare. Application of Wavelet transform to these velocity flows reveals that there is major enhancement of velocity oscillations in the high-frequency regime (5-8 mHz), while there is feeble enhancement in the p mode oscillations (2-5 mHz) in the aforementioned location. It has been recently shown that flares can induce high-frequency global oscillations in the Sun. Therefore, it appears that during the flare process there might be a common origin for the excitation of local and global high-frequency oscillations in the Sun.

  19. Observed inflation-deflation cycles at Popocatepetl volcano using tiltmeters and its possible correlation with regional seismic activity in Mexico

    Contreras Ruiz Esparza, M. G., Sr.; Jimenez Velazquez, J. C., Sr.; Valdes Gonzalez, C. M., Sr.; Reyes Pimentel, T. A.; Galaviz Alonso, S. A.

    2014-12-01

    Popocatepetl, the smoking mountain, is a stratovolcano located in central Mexico with an elevation of 5450 masl. The active volcano, close to some of the largest urban centers in Mexico - 60 km and 30 km far from Mexico City and Puebla, respectively - poses a high hazard to an estimated population of 500 thousand people living in the vicinity of the edifice. Accordingly, in July 1994 the Popocatepetl Volcanological Observatory (POVO) was established. The observatory is operated and supported by the National Center for Disaster Prevention of Mexico (CENAPRED), and is equipped to fully monitor different aspects of the volcanic activity. Among the instruments deployed, we use in this investigation two tiltmometers and broad-band seismometers at two sites (Chipiquixtle and Encinos), which send the information gathered continuously to Mexico City.In this research, we study the characteristics of the tiltmeters signals minutes after the occurrence of certain earthquakes. The Popocatepetl volcano starts inflation-deflation cycles due to the ground motion generated by events located at certain regions. We present the analysis of the tiltmeters and seismic signals of all the earthquakes (Mw>5) occurred from January 2013 to June 2014, recorded at Chipiquixtle and Encinos stations. First, we measured the maximum tilt variation after each earthquake. Next, we apply a band-pass filter for different frequency ranges to the seismic signals of the two seismic stations, and estimated the total energy of the strong motion phase of the seismic record. Finally, we compared both measurements and observed that the maximum tilt variations were occurring when the maximum total energy of the seismic signals were in a specific frequency range. We also observed that the earthquake records that have the maximum total energy in that frequency range were the ones with a epicentral location south-east of the volcano. We conclude that our observations can be used set the ground for an early

  20. Hubble Space Telescope Spectroscopic Observations of the Narrow-Line Region in Nearby Low-Luminosity Active Galactic Nuclei

    Walsh, Jonelle L; Ho, Luis C; Filippenko, Alexei V; Rix, Hans-Walter; Shields, Joseph C; Sarzi, Marc; Sargent, Wallace L W

    2008-01-01

    (Abridged) We present STIS observations of 14 nearby low-luminosity active galactic nuclei, including 13 LINERs and 1 Seyfert, taken at multiple parallel slit positions centered on the galaxy nuclei and covering the H-alpha spectral region. For each galaxy, we measure the emission-line velocities, line widths, and strengths, to map out the inner narrow-line region structure. There is a wide diversity among the velocity fields: in a few galaxies the gas is clearly in disk-like rotation, while in other galaxies the gas kinematics appear chaotic or are dominated by radial flows with multiple velocity components. The [S II] line ratio indicates a radial stratification in gas density, with a sharp increase within the inner 10-20 pc, in the majority of the Type 1 objects. We examine how the [N II] 6583 line width varies as a function of aperture size over a range of spatial scales, extending from scales comparable to the black hole's sphere of influence to scales dominated by the host galaxy's bulge. For most galax...

  1. Solar ALMA: Observation-Based Simulations of the mm and sub-mm Emissions from Active Regions

    Fleishman, G.; Loukitcheva, M.; Nita, G.

    2015-12-01

    We developed an efficient algorithm integrated in our 3D modeling tool, GX Simulator (Nita et al. 2015), allowing quick computation of the synthetic intensity and polarization maps of solar active regions (AR) in the ALMA spectral range.

  2. Reconstructing the Subsurface Three-Dimensional Magnetic Structure of A Solar Active Region Using SDO/HMI Observations

    Chintzoglou, Georgios; 10.1088/2041-8205/764/1/L1

    2013-01-01

    A solar active region (AR) is a three-dimensional magnetic structure formed in the convection zone, whose property is fundamentally important for determining the coronal structure and solar activity when emerged. However, our knowledge on the detailed 3-D structure prior to its emergence is rather poor, largely limited by the low cadence and sensitivity of previous instruments. Here, using the 45-second high-cadence observations from the Helioseismic and Magnetic Imager (\\emph{HMI}) onboard the Solar Dynamics Observatory (\\emph{SDO}), we are able for the first time to reconstruct a 3-D datacube and infer the detailed subsurface magnetic structure of NOAA AR 11158 and to characterize its magnetic connectivity and topology. This task is accomplished with the aid of the image-stacking method and advanced 3-D visualization. We find that the AR consists of two major bipoles, or four major polarities. Each polarity in 3-D shows interesting tree-like structure, i.e. while the root of the polarity appears as a single...

  3. Solar ALMA: Observation-Based Simulations of the mm and sub-mm Emissions from Active Regions

    Fleishman, Gregory; Nita, Gelu

    2015-01-01

    We developed an efficient algorithm integrated in our 3D modeling tool, GX Simulator (Nita et al. 2015), allowing quick computation of the synthetic intensity and polarization maps of solar active regions (AR) in the ALMA spectral range. The algorithm analyzes the photospheric input (white light and magnetogram) to classify a given photospheric pixel to belong to a given photospheric structure. Then, a 1D chromospheric model (Fontenla et al. 2009) is added on top of each pixel, which forms a chromospheric model of the AR. Next step is computation of the mm and sub-mm emission produced from this chromosphere model. A huge advantage of this approach is that emission from any given AR can be synthesized very fast, on the order of a few minutes after the AR selection. Using the GX Simulator tool it is also possible to produce synthetic maps of the microwave (gyroresonance) and EUV emission from the same AR model and compare them with the ALMA synthetic maps and with the corresponding observed microwave and/or EUV...

  4. Simultaneous Solar Maximum Mission and Very Large Array (VLA) observations of solar active regions. Semiannual Progress Report, 1 February 1985-30 January 1986

    Simultaneous observations of solar active regions with the Solar Maximum Mission (SMM) Satellite and the Very Large Array (VLA) have been obtained and analyzed. Combined results enhance the scientific return for beyond that expeted from using either SMM or VLA alone. A total of two weeks of simultaneous SMM/VLA data were obtained. The multiple wavelength VLA observations were used to determine the temperature and magnetic structure at different heights within coronal loops. These data are compared with simultaneous SMM observations. Several papers on the subject are in progress. They include VLA observations of compact, transient sources in the transition region; simultaneous SMM/VLA observations of the coronal loops in one active region and the evolution of another one; and sampling of the coronal plasma using thermal cyclotron lines (magnetic field - VLA) and soft X ray spectral lines (electron density and electron temperaure-SMM)

  5. Light and electron microscopic observation of the active peripheral regions of the keloids following electron ray irradiation

    Yamaguchi, Hiroshi [Kanazawa Medical univ., Uchinada, Ishikawa (Japan)

    1995-03-01

    The present study was designed to investigate changes in the active peripheral region of keloid before and after irradiation with 4 MeV electrons in 25 patients. Thirteen patients were treated with a daily dose of 5 Gy for consecutive 5 days (a total dose of 25 Gy) one week after total keloid excision and the other 12 were treated conservatively with a weekly dose of 4 Gy 3 times (one course) to a total of 3 courses at intervals of 2 months (a total dose of 36 Gy). Specimens were collected from the active peripheral region of keloids before and after electron irradiation for light and electron microscopy. Light microscopy revealed that the number of mast cells was significantly decreased after electron irradiation, corresponding to the clinical improvement. Electron microscopic findings before irradiation included active fibroblasts containing well-developed rough endoplasmic reticulum, nucleus having sharp indentations towards its center, and immature elastic fibers in the extracellular space. After irradiation, electron microscopy revealed that fibroblasts were less active and the rough endoplasmic reticulum and Golgi apparatus appeared to be undeveloped with many vacuoles. In the extracellular space, elastosis was found. The average diameter of the collagen fibrils in the peripheral region of the keloid tissue was increased. Electron irradiation may correct abnormal wound healing of keloids by suppressing the abnormal production of collagen by fibroblasts. In addition, electron irradiation promote the maturation of the existing extracellular matrix, leading to the formation of a mature scar. Furthermore, the low recurrence rate suggests that the effect of the electrons against keloid tissue is persistent. (N.K.).

  6. Evolution of Active Regions

    van Driel-Gesztelyi, Lidia; Green, Lucie May

    2015-09-01

    The evolution of active regions (AR) from their emergence through their long decay process is of fundamental importance in solar physics. Since large-scale flux is generated by the deep-seated dynamo, the observed characteristics of flux emergence and that of the subsequent decay provide vital clues as well as boundary conditions for dynamo models. Throughout their evolution, ARs are centres of magnetic activity, with the level and type of activity phenomena being dependent on the evolutionary stage of the AR. As new flux emerges into a pre-existing magnetic environment, its evolution leads to re-configuration of small-and large-scale magnetic connectivities. The decay process of ARs spreads the once-concentrated magnetic flux over an ever-increasing area. Though most of the flux disappears through small-scale cancellation processes, it is the remnant of large-scale AR fields that is able to reverse the polarity of the poles and build up new polar fields. In this Living Review the emphasis is put on what we have learned from observations, which is put in the context of modelling and simulation efforts when interpreting them. For another, modelling-focused Living Review on the sub-surface evolution and emergence of magnetic flux see Fan (2009). In this first version we focus on the evolution of dominantly bipolar ARs.

  7. Semiannual and solar activity variations of daytime plasma observed by DEMETER in the ionosphere-plasmasphere transition region

    Li, L. Y.; Cao, J. B.; Yang, J. Y.; Berthelier, J. J.; Lebreton, J.-P.

    2015-12-01

    Using the plasma data of Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) satellite and the NRLMSISE-00 atmospheric model, we examined the semiannual and solar activity variations of the daytime plasma and neutral composition densities in the ionosphere-plasmasphere transition region (~670-710 km). The results demonstrate that the semiannually latitudinal variation of the daytime oxygen ions (O+) is basically controlled by that of neutral atomic oxygen (O), whereas the latitude distributions of the helium and hydrogen ions (He+ and H+) do not fully depend on the neutral atomic helium (He) and hydrogen (H). The summer enhancement of the heavy oxygen ions is consistent with the neutral O enhancement in the summer hemisphere, and the oxygen ion density has significantly the summer-dense and winter-tenuous hemispheric asymmetry with respect to the dip equator. Although the winter enhancements of the lighter He+ and H+ ions are also associated with the neutral He and H enhancements in the winter hemisphere, the high-density light ions (He+ and H+) and electrons (e-) mainly appear at the low and middle magnetic latitudes (|λ| < 50°). The equatorial accumulations of the light plasma species indicate that the light charged particles (He+, H+, and e-) are easily transported by some equatorward forces (e.g., the magnetic mirror force and centrifugal force). The frequent Coulomb collisions between the charged particles probably lead to the particle trappings at different latitudes. Moreover, the neutral composition densities also influence their ion concentrations during different solar activities. From the low-F10.7 year (2007-2008) to the high-F10.7 year (2004-2005), the daytime oxygen ions and electrons increase with the increasing neutral atomic oxygen, whereas the daytime hydrogen ions tend to decrease with the decreasing neutral atomic hydrogen. The helium ion density has no obvious solar activity variation, suggesting that the

  8. Evolution of Magnetic Field and Energy in A Major Eruptive Active Region Based on SDO/HMI Observation

    Sun, Xudong; Liu, Yang; Wiegelmann, Thomas; Hayashi, Keiji; Chen, Qingrong; Thalmann, Julia

    2012-01-01

    We report the evolution of magnetic field and its energy in NOAA active region 11158 over 5 days based on a vector magnetogram series from the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamic Observatory (SDO). Fast flux emergence and strong shearing motion led to a quadrupolar sunspot complex that produced several major eruptions, including the first X-class flare of Solar Cycle 24. Extrapolated non-linear force-free coronal fields show substantial electric current and free energy increase during early flux emergence near a low-lying sigmoidal filament with sheared kilogauss field in the filament channel. The computed magnetic free energy reaches a maximum of ~2.6e32 erg, about 50% of which is stored below 6 Mm. It decreases by ~0.3e32 erg within 1 hour of the X-class flare, which is likely an underestimation of the actual energy loss. During the flare, the photospheric field changed rapidly: horizontal field was enhanced by 28% in the core region, becoming more inclined and more parallel to...

  9. Simultaneous solar maximum mission (SMM) and very large array (VLA) observations of solar active regions. Final technical report, 1 February 1985-31 January 1991

    Very Large Array observations at 20 cm wavelength can detect the hot coronal plasma previously observed at soft x ray wavelengths. Thermal cyclotron line emission was detected at the apex of coronal loops where the magnetic field strength is relatively constant. Detailed comparison of simultaneous Solar Maximum Mission (SMM) Satellite and VLA data indicate that physical parameters such as electron temperature, electron density, and magnetic field strength can be obtained, but that some coronal loops remain invisible in either spectral domain. The unprecedent spatial resolution of the VLA at 20 cm wavelength showed that the precursor, impulsive, and post-flare components of solar bursts originate in nearby, but separate loops or systems of loops.. In some cases preburst heating and magnetic changes are observed from loops tens of minutes prior to the impulsive phase. Comparisons with soft x ray images and spectra and with hard x ray data specify the magnetic field strength and emission mechanism of flaring coronal loops. At the longer 91 cm wavelength, the VLA detected extensive emission interpreted as a hot 10(exp 5) K interface between cool, dense H alpha filaments and the surrounding hotter, rarefield corona. Observations at 91 cm also provide evidence for time-correlated bursts in active regions on opposite sides of the solar equator; they are attributed to flare triggering by relativistic particles that move along large-scale, otherwise-invisible, magnetic conduits that link active regions in opposite hemispheres of the Sun

  10. VLF/LF signal studies of the ionospheric response to strong seismic activity in the Far Eastern region combining the DEMETER and ground-based observations

    Rozhnoi, A.; Solovieva, M.; Parrot, M.; Hayakawa, M.; Biagi, P.-F.; Schwingenschuh, K.; Fedun, V.

    The paper presents the results of a joint analysis of ground-based and satellite observations of very low-frequency and low-frequency (VLF/LF) signals during periods of strong seismic activity in the region of Kuril Islands and Japan in 2004-2010. Ground and satellite data was processed using a method based on the difference between the real signal in nighttime and that of a model. The results of the analysis show a good correlation between ground-based and satellite data for several cases of strong (M ⩾ 6.8) earthquakes.

  11. Chromospheric magnetic field of an active region filament using the He I triplet and the primary observation of filaments (prominences) using New Vacuum Solar Tower of China

    Xu, Zhi; Lagg, A.; Solanki, S.; Liu, Z.; New Vacuum Solar Telescope Observers

    2013-07-01

    There are two parts in my presentation. In the first part I present the magnetic field measurement of an active region filament using the full Stokes profiles of He I 10830 and Si I 10827 band when the filament in its stable phase. This observation was fulfilled using German Vacuum Tower Telescope (VTT). The vector magnetic field and Doppler velocity map both in the photosphere and chromosphere were observed and analyzed co-temporally and co-spatially. The observation findings reveal that we were observing the emergence of a flux rope with a subsequent formation of a filament. In the second part, I would like to exhibit another ground-based observation facility, 1m New Vacuum Solar Telescope (NVST) located in Fu-Xian Lake Solar Observatory of China. After the basic introduction including the location and instrumentations, I give some high lights including granulation, faculae, micro-flares, jets, and filaments or prominence since the first running in 2010, showing our potential ability to do high-resolution solar observation from the ground. Observation proposals from the international solar community are well appreciated in future.

  12. Time-resolved emission from bright hot pixels of an active region observed in the EUV band with SDO/AIA and multi-stranded loop modeling

    Tajfirouze, E; Petralia, A; Testa, P

    2015-01-01

    Evidence for small amounts of very hot plasma has been found in active regions and might be the indication of an impulsive heating, released at spatial scales smaller than the cross section of a single loop. We investigate the heating and substructure of coronal loops in the core of one such active region by analyzing the light curves in the smallest resolution elements of solar observations in two EUV channels (94 A and 335 A) from the Atmospheric Imaging Assembly on-board the Solar Dynamics Observatory. We model the evolution of a bundle of strands heated by a storm of nanoflares by means of a hydrodynamic 0D loop model (EBTEL). The light curves obtained from the random combination of those of single strands are compared to the observed light curves either in a single pixel or in a row of pixels, simultaneously in the two channels and using two independent methods: an artificial intelligent system (Probabilistic Neural Network, PNN) and a simple cross-correlation technique. We explore the space of the param...

  13. Variations of VLF/LF signals observed on the ground and satellite during a seismic activity in Japan region in May–June 2008

    A. Rozhnoi

    2010-03-01

    Full Text Available Signals of two Japanese transmitters (22.2 kHz and 40 kHz recorded on the ground VLF/LF station in Petropavlovsk-Kamchatsky and on board the DEMETER French satellite have been analyzed during a seismic activity in Japan in May–June 2008. The period of analysis was from 18 April to 27 June. During this time two rather large earthquakes occurred in the north part of Honshu Island – 7 May (M=6.8 and 13 June (M=6.9. The ground and satellite data were processed by a method based on the difference between the real signal in nighttime and the model one. For ground observations a clear decrease in both signals has been found several days before the first earthquake. For the second earthquake anomalies were detected only in JJI signal. The epicenters of earthquakes were in reliable reception zone of 40 kHz signal on board the DEMETER. Signal enhancement above the seismic active region and significant signal intensity depletion in the magnetically conjugate area has been found for satellite observation before the first earthquake. Anomalies in satellite data coincide in time with those in the ground-based observation.

  14. Dose-dependent effects of isoflurane on regional activity and neural network function: A resting-state fMRI study of 14 rhesus monkeys: An observational study.

    Lv, Peilin; Xiao, Yuan; Liu, Bin; Wang, Yuqing; Zhang, Xiang; Sun, Huaiqiang; Li, Fei; Yao, Li; Zhang, Wenjing; Liu, Lu; Gao, Xin; Wu, Min; Tang, Yingying; Chen, Qin; Gong, Qiyong; Lui, Su

    2016-01-12

    The dose-dependent effect of isoflurane on cerebral regional activity and functional connectivity (FC) in 14 rhesus monkeys was investigated using resting-state functional MRI. Amplitude of low-frequency fluctuations (ALFF) decreased in the cerebellum, visual cortex, and cortico-subcortical network when the isoflurane dose changed from 1.0 to 1.3 MAC. ALFF decreased in the arousal system, cerebellum, sensory, visual areas, cortico-subcortical network and default mode network and increased in the bilateral dorsal prefrontal cortices, frontal eye fields and motor-related areas from 1.0 to 1.6 MAC. FC of the default mode network, frontal-parietal, cortico-subcortical, motor, sensory, auditory and visual areas was reduced when isoflurane increased from 1.0 to 1.3 MAC. FC decreased in more widespread areas, especially in regions of cortico-subcortical networks and limbic systems, when isoflurane further increased from 1.0 to 1.6 MAC. Both dose-dependent decreased and increased ALFF were separately observed, while FC deteriorated as the anesthesia deepened. These results suggest that changes continue to occur past the loss of consciousness, and the dose-dependent effects of isoflurane are different with regard to regional function and neural network integration. PMID:26633103

  15. Sodium Lidar-observed Strong Inertia-gravity Wave Activities in the Mesopause Region over Fort Collins, Colorado (41 deg N, 105 deg W)

    Li, Tao; She, C. -Y.; Liu, Han-Li; Leblanc, Thierry; McDermid, I. Stuart

    2007-01-01

    In December 2004, the Colorado State University sodium lidar system at Fort Collins, Colorado (41 deg N, 105 deg W), conducted an approximately 80-hour continuous campaign for the simultaneous observations of mesopause region sodium density, temperature, and zonal and meridional winds. This data set reveals the significant inertia-gravity wave activities with a period of approximately 18 hours, which are strong in both wind components since UT day 338 (second day of the campaign), and weak in temperature and sodium density. The considerable variability of wave activities was observed with both wind amplitudes growing up to approximately 40 m/s at 95-100 km in day 339 and then decreasing dramatically in day 340. We also found that the sodium density wave perturbation is correlated in phase with temperature perturbation below 90 km, and approximately 180 deg out of phase above. Applying the linear wave theory, we estimated the wave horizontal propagation direction, horizontal wavelength, and apparent horizontal phase speed to be approximately 25 deg south of west, approximately 1800 +/- 150 km, and approximately 28 +/- 2 m/s, respectively of wave intrinsic period, intrinsic phase speed, and vertical wavelength were also estimated. While the onset of enhanced inertia-gravity wave amplitude in the night of 338 was observed to be in coincidence with short-period gravity wave breaking via convective instability, the decrease of inertia-gravity wave amplitude after noon of day 339 was also observed to coincide with the development of atmospheric dynamical instability layers with downward phase progression clearly correlated with the 18-hour inertia-gravity wave, suggesting likely breaking of this inertia-gravity wave via dynamical (shear) instability.

  16. Time-resolved Emission from Bright Hot Pixels of an Active Region Observed in the EUV Band with SDO/AIA and Multi-stranded Loop Modeling

    Tajfirouze, E.; Reale, F.; Petralia, A.; Testa, P.

    2016-01-01

    Evidence of small amounts of very hot plasma has been found in active regions and might be an indication of impulsive heating released at spatial scales smaller than the cross-section of a single loop. We investigate the heating and substructure of coronal loops in the core of one such active region by analyzing the light curves in the smallest resolution elements of solar observations in two EUV channels (94 and 335 Å) from the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory. We model the evolution of a bundle of strands heated by a storm of nanoflares by means of a hydrodynamic 0D loop model (EBTEL). The light curves obtained from a random combination of those of single strands are compared to the observed light curves either in a single pixel or in a row of pixels, simultaneously in the two channels, and using two independent methods: an artificial intelligent system (Probabilistic Neural Network) and a simple cross-correlation technique. We explore the space of the parameters to constrain the distribution of the heat pulses, their duration, their spatial size, and, as a feedback on the data, their signatures on the light curves. From both methods the best agreement is obtained for a relatively large population of events (1000) with a short duration (less than 1 minute) and a relatively shallow distribution (power law with index 1.5) in a limited energy range (1.5 decades). The feedback on the data indicates that bumps in the light curves, especially in the 94 Å channel, are signatures of a heating excess that occurred a few minutes before.

  17. Seismology of Flaring and Dormant Active Regions

    Maurya, R.A.

    2013-01-01

    We study photospheric and sub-photospheric properties of active and quiet regions observed during 11-17 February 2011 including the first X-class flare X2.2 of the solar cycle 24 which occurred in the active region NOAA 11158 on 15 February 2011. The p-mode parameters and sub-photospheric flows are computed from the ring-diagrams and inversions. We found larger frequency shifts in active regions than quiet regions. The active region NOAA 11158 shows stronger twisted sub-photospheric flows tha...

  18. Active Region Soft X-Ray Spectra as Observed Using Sounding Rocket Measurements from the Solar Aspect Monitor (SAM), - a Modified SDO/EVE Instrument

    Wieman, S. R.; Didkovsky, L. V.; Woods, T. N.; Jones, A. R.; Caspi, A.; Warren, H. P.

    2015-12-01

    Observations of solar active regions (ARs) in the soft x-ray spectral range (0.5 to 3.0 nm) were made on sounding rocket flight NASA 36.290 using a modified Solar Aspect Monitor (SAM), a pinhole camera on the EUV Variability Experiment (EVE) sounding rocket instrument. The suite of EVE rocket instruments is designed for under-flight calibrations of the orbital EVE on SDO. While the sounding rocket EVE instrument is for the most part a duplicate of the EVE on SDO, the SAM channel on the rocket version was modified in 2012 to include a free-standing transmission grating so that it could provide spectrally resolved images of the solar disk with the best signal to noise ratio for the brightest features on it, such as ARs. Calibrations of the EVE sounding rocket instrument at the National Institute of Standards and Technology Synchrotron Ultraviolet Radiation Facility (NIST SURF) have provided a measurement of the SAM absolute spectral response function and a mapping of wavelength separation in the grating diffraction pattern. For solar observations, this spectral separation is on a similar scale to the spatial size of the AR on the CCD, so dispersed AR images associated with emission lines of similar wavelength tend to overlap. Furthermore, SAM shares a CCD detector with MEGS-A, a separate EVE spectrometer channel, and artifacts of the MEGS-A signal (a set of bright spectral lines) appear in the SAM images. For these reasons some processing and analysis of the solar images obtained by SAM must be performed in order to determine spectra of the observed ARs. We present a method for determining AR spectra from the SAM rocket images and report initial soft X-ray spectra for two of the major active regions (AR11877 and AR11875) observed on flight 36.290 on 21 October 2013 at about 18:30 UT. We also compare our results with concurrent measurements from other solar soft x-ray instrumentation.

  19. Three spacecraft observe Jupiter's glowing polar regions

    1996-09-01

    also privileged to be the last observer with IUE" says Rene Prang of Orsay, France, who was in charge of the Jupiter programme. "At the end it provided us wit 800 observations of Jupiter, so it was still doing important work at the leading edge of planetary astronomy and space research". Created jointly by NASA, the UK government and ESA, IUE was supposed to last for three years, when it was launched on 26 January 1978. Instead, the 700-kilogram spacecraft went on supplying astronomers with ultraviolet spectroscopic information available from no other spacecraft until the launch of the Hubble Space Telescope in 1990. As the only space observatory offering them a hands-on mode of operation, at ESA's ground station at Villafranca near Madrid, IUE was a favourite with astronomers. An astounding total of 114,000 individual observations of planets, stars, galaxies and quasars assures the spacecraft a cherished place in the history of astronomy. IUE supplied the bedrock ultraviolet data on top events during its lifetime. These included the apparition of Halley's Comet in 1986. At the comet's approach in September 1985, IUE detected the ultraviolet signature of water molecules, and regular observations thereafter showed that the comet shed 300 million tonnes of water during its visit to the Sun's vicinity. With the explosion of a star in the Large Magellan Cloud, as Supernova 1987A, IUE was trained instantly on the scene. Comparisons with previous IUE observations of the same region revealed exactly which star had blown up. The characteristic emissions of chemical elements flung into space by the explosion were also identified, IUE's detection of a delayed light echo, from a ring of dust surrounding the defunct star, later enabled the Hubble Space Telescope to measure the distance to Supernova 1987A precisely. Eruptions in the nuclei of active galaxies were a prominent theme in IUE's work throughout its lifetime. Intensive studies of selected galaxies, sometimes in concert

  20. Regional Activities Division. Papers.

    International Federation of Library Associations, The Hague (Netherlands).

    Papers on library network activities in Canada, the Third World, Japan, Malaysia, Brazil, and Sweden which were presented at the 1982 International Federation of Library Associations (IFLA) conference include: (1) "Canada: A Voluntary and Flexible Network," a review by Guy Sylvestre of the political, social, and economic structures affecting…

  1. Regional radiological observations of the environment

    After having recalled the objective of regional radiological observations (establishment of an updated referential of radioactivity levels in some parts of the environment which are typical of the concerned territory), and indicated the three main steps of these observations (definition of a methodology which may differ from one territory to the other, sampling and analysis, assessment of the radiological status of the studied territory), this report presents a methodology which can be applied to big rivers and predominantly agricultural territories. The radiological observations of different areas are reported (Val de Loire, Rhone valley, areas of persistence like mountains, or mining areas). Maps indicate the sampling location and the analysed products (food, soil, plants) and report of the ground or aquatic environment analysis, or available data and sampling strategy are given. The New Caledonia radiological observation is also reported

  2. Observational Study of Solar Magnetic Active Phenomena

    Hongqi Zhang

    2006-06-01

    The electric current separated into two parts reflected the quantative properties of heterogeneity and chirality of magnetic field, and defined them as the shear and twist components of current. We analyze the basic configuration and evolution of superactive region NOAA 6580-6619-6659. It is found that the contribution of the twist component of current cannot be reflected in the normal analysis of the magnetic shear and gradient of the active regions. The observational evidence of kink magnetic ropes generated from the subatmosphere cannot be found completely in some super delta active regions.

  3. The Magnetic Free Energy in Active Regions

    Metcalf, Thomas R.; Mickey, Donald L.; LaBonte, Barry J.

    2001-01-01

    The magnetic field permeating the solar atmosphere governs much of the structure, morphology, brightness, and dynamics observed on the Sun. The magnetic field, especially in active regions, is thought to provide the power for energetic events in the solar corona, such as solar flares and Coronal Mass Ejections (CME) and is believed to energize the hot coronal plasma seen in extreme ultraviolet or X-rays. The question remains what specific aspect of the magnetic flux governs the observed variability. To directly understand the role of the magnetic field in energizing the solar corona, it is necessary to measure the free magnetic energy available in active regions. The grant now expiring has demonstrated a new and valuable technique for observing the magnetic free energy in active regions as a function of time.

  4. Observations and modeling of UHF-band scintillation occurrence probability over the low-latitude region of China during the maximum activity of solar cycle 24

    Zhang, H.; Liu, Y.; Wu, J.; Xu, T.; Sheng, D.

    2015-01-01

    The climatological characteristics of UHF-band scintillations over the low-latitude region of China were investigated by analyzing the observations recorded at three stations of our regional network of satellite-beacon-based scintillation monitoring in 2013. The three stations are Hainan (geographic 20.0° N, 110.3° E; geomagnetic 10.1° N, 177.4° W, dip 28.2°), Guangzhou (geographic 23.0° N, 113.0° E; geomagnetic 13.1° N, 174.8° W, dip 33.9°) and Kunming (geographic 25.6° N, 103.7° E; geomagnetic 15.7° N, 176.4° E, dip 39.0°), located at low latitudes of China. The variations of UHF-band scintillation occurrence with latitude, time and season are presented in detail to understand the morphology and climatology of ionospheric scintillations over the low-latitude region of China. An equinoctial asymmetry in the occurrences of scintillation and an obvious difference of the onset time of scintillations between Hainan and Kunming is noted in this data set. Subsequently, the ionosonde data are utilized to study the possible causes of the asymmetry between two equinoxes. The observations suggest that the mean critical frequency (foF2) at 20:00 LT (12:00 UT) in the autumnal equinoctial months (September and October) and the vernal equinoctial months (March and April) has a similar asymmetry. The ratio of the mean foF2 between two equinoxes is proportional to the ratio between the maximum scintillation occurrence in the autumnal equinox and in the vernal equinox. Therefore, this ratio can act as a proxy for the equinoctial asymmetry in the occurrences of scintillation over the low-latitude region of China, and can be used to model the equinoctial asymmetry in our empirical climatological model of scintillation occurrence probability (CMSOP). The CMSOP can provide the predictions of the occurrences of scintillation over the low-latitude region of China and was validated in this study.

  5. A paradigm shift in stormflow predictions for active tectonic regions with large-magnitude storms: generalisation of catchment observations by hydraulic sensitivity analysis and insight into soil-layer evolution

    Makoto Tani

    2013-01-01

    In active tectonic regions with large-magnitude storms, it is still difficult to predict stormflow responses by distributed runoff models from the catchment properties without a parameter calibration using observational data. This paper represents an attempt to address the problem. A review of observational studies showed that the stormflow generation mechanism was heterogeneous and complex, but stormflow responses there were simply simulated by a single tank with a drainage ho...

  6. A paradigm shift in stormflow predictions for active tectonic regions with large-magnitude storms: generalisation of catchment observations by hydraulic sensitivity analysis and insight into soil-layer evolution

    Tani, Makoto

    2013-01-01

    In active tectonic regions with large-magnitude storms, it is still difficult to predict stormflow responses by distributed runoff models from the catchment properties without a parameter calibration using observational data. This paper represents an attempt to address the problem. A review of observational studies showed that the stormflow generation mechanism was heterogeneous and complex, but stormflow responses there were simply simulated by a single tank with a drainage hole when the sto...

  7. Magnetic Helicity Injection in Solar Active Regions

    Hong-Qi Zhang

    2006-01-01

    We present the evolution of magnetic field and its relationship with magnetic (current) helicity in solar active regions from a series of photospheric vector magnetograms obtained by Huairou Solar Observing Station, longitudinal magnetograms by MDI of SOHO and white light images of TRACE. The photospheric current helicity density is a quantity reflecting the local twisted magnetic field and is related to the remaining magnetic helicity in the photosphere, even if the mean current helicity density brings the general chiral property in a layer of solar active regions. As new magnetic flux emerges in active regions, changes of photospheric current helicity density with the injection of magnetic helicity into the corona from the subatmosphere can be detected, including changes in sign caused by the injection of magnetic helicity of opposite sign. Because the injection rate of magnetic helicity and photospheric current helicity density have different means in the solar atmosphere,the injected magnetic helicity is probably not proportional to the current helicity density remaining in the photosphere. The evidence is that rotation of sunspots does not synchronize exactly with the twist of photospheric transverse magnetic field in some active regions (such as, delta active regions). They represent different aspects of magnetic chirality. A combined analysis of the observational magnetic helicity parameters actually provides a relative complete picture of magnetic helicity and its transfer in the solar atmosphere.

  8. Active Region Emergence & Remote Flares

    Fu, Yixing; Welsch, Brian T.

    2015-01-01

    We study the effect of newly emerged solar active regions (ARs) on the large-scale magnetic environment of pre-existing ARs (PEARs). We first present a theoretical approach to quantify the "interaction energy" between new ARs and PEARs as the difference between (i) the summed magnetic energies of their individual potential fields and (ii) the energy of their superposed potential fields. We expect that this interaction energy can, depending upon the relative arrangements of newly emerged and P...

  9. Solar Eruptions Initiated in Sigmoidal Active Regions

    Savcheva, Antonia

    2016-07-01

    active regions that have been shown to possess high probability for eruption. They present a direct evidence of the existence of flux ropes in the corona prior to the impulsive phase of eruptions. In order to gain insight into their eruptive behavior and how they get destabilized we need to know their 3D magnetic field structure. First, we review some recent observations and modeling of sigmoidal active regions as the primary hosts of solar eruptions, which can also be used as useful laboratories for studying these phenomena. Then, we concentrate on the analysis of observations and highly data-constrained non-linear force-free field (NLFFF) models over the lifetime of several sigmoidal active regions, where we have captured their magnetic field structure around the times of major flares. We present the topology analysis of a couple of sigmoidal regions pointing us to the probable sites of reconnection. A scenario for eruption is put forward by this analysis. We demonstrate the use of this topology analysis to reconcile the observed eruption features with the standard flare model. Finally, we show a glimpse of how such a NLFFF model of an erupting region can be used to initiate a CME in a global MHD code in an unprecedented realistic manner. Such simulations can show the effects of solar transients on the near-Earth environment and solar system space weather.

  10. Evolution of active region outflows throughout an active region lifetime

    Zangrilli, L

    2016-01-01

    We have shown previously that SOHO/UVCS data allow us to detect active region (AR) outflows at coronal altitudes higher than those reached by other instrumentation. These outflows are thought to be a component of the slow solar wind. Our purpose is to study the evolution of the outflows in the intermediate corona from AR 8100, from the time the AR first forms until it dissolves, after several transits at the solar limb. Data acquired by SOHO/UVCS at the time of the AR limb transits, at medium latitudes and at altitudes ranging from 1.5 to 2.3 R_sun, were used to infer the physical properties of the outflows through the AR evolution. To this end, we applied the Doppler dimming technique to UVCS spectra. These spectra include the H I Lyman alpha line and the O VI doublet lines at 1031.9 and 1037.6 A. Plasma speeds and electron densities of the outflows were inferred over several rotations of the Sun. AR outflows are present in the newly born AR and persist throughout the entire AR life. Moreover, we found two t...

  11. Transition-Region Velocity Oscillations Observed by EUNIS-06

    Jess, D B; Thomas, R J; Brosius, J W; Mathioudakis, M; Keenan, F P

    2008-01-01

    Spectroscopic measurements of AR NOAA 10871, obtained with the Extreme Ultraviolet Normal Incidence Spectrograph (EUNIS) sounding rocket instrument on 2006 April 12, reveal velocity oscillations in the He II 303.8 Angstrom emission line formed at T ~ 50000K. The oscillations appear to arise in a bright active-region loop arcade about 25" wide which crosses the EUNIS slit. The period of these transition region oscillations is 26 +/- 4 s, coupled with a velocity amplitude of +/- 10 km/s, detected over 4 complete cycles. Similar oscillations are observed in lines formed at temperatures up to T ~ 400000K, but we find no evidence for the coupling of these velocity oscillations with corresponding phenomena in the corona. We interpret the detected oscillations as originating from an almost purely adiabatic plasma, and infer that they are generated by the resonant transmission of MHD waves through the lower active-region atmospheres. Through use of seismological techniques, we establish that the observed velocity osc...

  12. New model of iron spectra in the extreme ultraviolet and application to SERTS and EUV observations: A solar active region and capella

    Brickhouse, N. S.; Raymond, J. C.; Smith, B. W.

    1995-04-01

    We report new predictions for the EUV spectral emission of FeIX-FeXXIV, based on data now available from the Solar EUV Rocket Telescope and Spectrograph (SERTS) and the Extreme Ultraviolet Explorer (EUVE) spectrometers. The iron spectral emission model is the first result of a larger effort to revise the Raymond & Smith model and to update the atomic rates. We present here predicted emissivities for selected densities and temperatures applicable to various astrophysical plasmas. Comparisons of our predicted spectra with two recent observations provide important tests of the atomic data. They also test to some extent some basic assumptions of coronal emission codes: optically thin spectral lines and ionization equilibrium.

  13. Climate Outreach Using Regional Coastal Ocean Observing System Portals

    Anderson, D. M.; Hernandez, D. L.; Wakely, A.; Bochenek, R. J.; Bickel, A.

    2015-12-01

    Coastal oceans are dynamic, changing environments affected by processes ranging from seconds to millennia. On the east and west coast of the U.S., regional observing systems have deployed and sustained a remarkable diverse array of observing tools and sensors. Data portals visualize and provide access to real-time sensor networks. Portals have emerged as an interactive tool for educators to help students explore and understand climate. Bringing data portals to outreach events, into classrooms, and onto tablets and smartphones enables educators to address topics and phenomena happening right now. For example at the 2015 Charleston Science Technology Engineering and Math (STEM) Festival, visitors navigated the SECOORA (Southeast Coastal Ocean Observing regional Association) data portal to view the real-time marine meteorological conditions off South Carolina. Map-based entry points provide an intuitive interface for most students, an array of time series and other visualizations depict many of the essential principles of climate science manifest in the coastal zone, and data down-load/ extract options provide access to the data and documentation for further inquiry by advanced users. Beyond the exposition of climate principles, the portal experience reveals remarkable technologies in action and shows how the observing system is enabled by the activity of many different partners.

  14. Statistical analysis of acoustic wave parameters near active regions

    Soares, M Cristina Rabello; Scherrer, Philip H

    2016-01-01

    In order to quantify the influence of magnetic fields on acoustic mode parameters and flows in and around active regions, we analyse the differences in the parameters in magnetically quiet regions nearby an active region (which we call `nearby regions'), compared with those of quiet regions at the same disc locations for which there are no neighboring active regions. We also compare the mode parameters in active regions with those in comparably located quiet regions. Our analysis is based on ring diagram analysis of all active regions observed by HMI during almost five years. We find that the frequency at which the mode amplitude changes from attenuation to amplification in the quiet nearby regions is around 4.2 mHz, in contrast to the active regions, for which it is about 5.1 mHz. This amplitude enhancement (the `acoustic halo effect') is as large as that observed in the active regions, and has a very weak dependence on the wave propagation direction. The mode energy difference in nearby regions also changes...

  15. Status report of IOC Regional Activities

    IOC for UNESCO

    2011-01-01

    The IOC’s Regional Subsidiary Bodies play an important role in the implementation of the Commission’s programmes in the regions. These efforts are complemented by other IOC decentralized offices, and regional networks established by the IOC’s global programmes. The report provides an overview of the status of IOC Regional Activities.

  16. Statistical Analysis of Acoustic Wave Parameters Near Solar Active Regions

    Rabello-Soares, M. Cristina; Bogart, Richard S.; Scherrer, Philip H.

    2016-08-01

    In order to quantify the influence of magnetic fields on acoustic mode parameters and flows in and around active regions, we analyze the differences in the parameters in magnetically quiet regions nearby an active region (which we call “nearby regions”), compared with those of quiet regions at the same disk locations for which there are no neighboring active regions. We also compare the mode parameters in active regions with those in comparably located quiet regions. Our analysis is based on ring-diagram analysis of all active regions observed by the Helioseismic and Magnetic Imager (HMI) during almost five years. We find that the frequency at which the mode amplitude changes from attenuation to amplification in the quiet nearby regions is around 4.2 mHz, in contrast to the active regions, for which it is about 5.1 mHz. This amplitude enhacement (the “acoustic halo effect”) is as large as that observed in the active regions, and has a very weak dependence on the wave propagation direction. The mode energy difference in nearby regions also changes from a deficit to an excess at around 4.2 mHz, but averages to zero over all modes. The frequency difference in nearby regions increases with increasing frequency until a point at which the frequency shifts turn over sharply, as in active regions. However, this turnover occurs around 4.9 mHz, which is significantly below the acoustic cutoff frequency. Inverting the horizontal flow parameters in the direction of the neigboring active regions, we find flows that are consistent with a model of the thermal energy flow being blocked directly below the active region.

  17. Active region evolution in the chromosphere and transtition region

    Images in the C IV 1548 A and the Si II 1526 S lines taken with the ultraviolet spectrometer polarimeter (UVSP) instrument on board the Solar Maximum Mission (SMM) satellite were combined into movies showing the evolution of active regions and the neighboring supergranulation over several days. The data sets generally consist of 240 by 240 arc second rasters with 3 arc second pixels taken one per orbit (about every 90 minutes). The images are projected on a latitude/longitude grid to remove the forshortening as the region rotates across the solar disk and further processed to remove jitter and gain variations. Movies were made with and without differential rotation. Although there are occasional missing orbits, these series do not suffer from the long nighttime gaps that occur in observations taken at a single groundbased observatory and are excellent for studying changes on time scales of several hours. The longest sequence processed to date runs from 20 Oct. 1980 to 25 Oct. 1980. This was taken during an SMM flare buildup study on AR 2744. Several shorter sequences taken in 1980 and 1984 will also be shown. The results will be presented on a video disk which can be interactively controlled to view the movies

  18. SDO/HMI survey of emerging active regions for helioseismology

    Schunker, H; Birch, A C; Burston, R B; Gizon, L

    2016-01-01

    Observations from the Solar Dynamics Observatory (SDO) have the potential for allowing the helioseismic study of the formation of hundreds of active regions, which would enable us to perform statistical analyses. Our goal is to collate a uniform data set of emerging active regions observed by the SDO/HMI instrument suitable for helioseismic analysis up to seven days before emergence. We restricted the sample to active regions that were visible in the continuum and emerged into quiet Sun largely avoiding pre-existing magnetic regions. As a reference data set we paired a control region (CR), with the same latitude and distance from central meridian, with each emerging active region (EAR). We call this data set, which is currently comprised of 105 emerging active regions observed between May 2010 and November 2012, the SDO Helioseismic Emerging Active Region (SDO/HEAR) survey. To demonstrate the utility of a data set of a large number of emerging active regions, we measure the relative east-west velocity of the ...

  19. The Main Sequence of Explosive Solar Active Regions: Comparison of Emerging and Mature Active Regions

    Falconer, David; Moore, Ron

    2011-01-01

    For mature active regions, an active region s magnetic flux content determines the maximum free energy the active region can have. Most Large flares and CMEs occur in active regions that are near their free-energy limit. Active-region flare power radiated in the GOES 1-8 band increases steeply as the free-energy limit is approached. We infer that the free-energy limit is set by the rate of release of an active region s free magnetic energy by flares, CMEs and coronal heating balancing the maximum rate the Sun can put free energy into the active region s magnetic field. This balance of maximum power results in explosive active regions residing in a "mainsequence" in active-region (flux content, free energy content) phase space, which sequence is analogous to the main sequence of hydrogen-burning stars in (mass, luminosity) phase space.

  20. Homologous flares and the evolution of NOAA Active Region 2372

    A detailed record of the evolution of NOAA Active Region 2372 has been compiled by the FBS Homology Study Group. It was one of the most prolific flare-producing regions observed by SMM. The flares occurred in distinct stages which corresponded to particular evolutionary phases in the development of the active region magnetic field. By comparison with a similar but less productive active region, it is found that the activity seems to be related to the magnetic complexity of the region and the amount of shear in the field. Further, the soft X-ray emission in the quiescent active region is related to its flare rate. Within the broader definition of homology adopted, there was a degree of homology between the events within each stage of evolution of AR2372

  1. Pederson Current Dissipation In Emerging Active Regions

    Leake, James E.; Linton, M. G.

    2011-05-01

    Pederson current dissipation in emerging active regions. Certain regions of the solar atmosphere, such as the photosphere and chromosphere, as well as prominences, contain a significant amount of neutral atoms, and a complete description of the plasma requires including the effects of partial ionization. In the chromosphere the dissipation of Pederson currents is important for the evolution of emerging magnetic fields. Due to the relatively high number density in the chromosphere, the ion-neutral collision time-scale is much smaller than timescales associated with flux emergence. Hence we use a single-fluid approach to model the partially ionized plasma. Looking at both the emergence of large-scale sub-surface structures, and the emergence and reconnection of undulatory fields, we investigate the effect of Pederson current dissipation on the state of the emerging field, on magnetic reconnection and on dissipative heating of the atmosphere. Specifically we examine the effect of motions across fieldlines in the partially ionized regions, and how this can increase the free energy supplied to the corona by flux emergence. We also look at reconnection associated with flux emergence in the partially ionized atmosphere, and how this can account for observed small-scale brightenings (Ellerman Bombs).

  2. The Magnetic Classification of Solar Active Regions 1992 - 2015

    Jaeggli, Sarah A.; Norton, Aimee A.

    2016-01-01

    The purpose of this letter is to address a blind-spot in our knowledge of solar active region statistics. To the best of our knowledge there are no published results showing the variation of the Mount Wilson magnetic classifications as a function of solar cycle based on modern observations. We show statistics for all active regions reported in the daily Solar Region Summary from 1992 January 1 to 2015 December 31. We find that the $\\alpha$ and $\\beta$ class active regions (including all sub-g...

  3. Magnetic history of solar active regions

    An attempt was made to use recent magnetic observations to trace the history of a typical solar active region from birth to death. By comparing the short-term motions to the long-term spreading, it is demonstrated that the decay process is dominated, over periods ranging from days to months, by a random walk of field lines, with a diffusion constant of roughly 200 to 400 km2/sec. While the interaction between diffusion and differential rotation dictates the geometric pattern of the decaying region, the actual quantity of surviving flux appears to be less, and its ultimate annihilation more thorough, than would have been expected. This probably indicates a continued subsurface coupling between opposite polarity features. In addition, the long-range agreement between theory and observation is considerably improved by postulating the existence, in the middle latitudes of each hemisphere, of a systematic, poleward-moving meridional flow of about 3 m/sec. The outlook for being able to make continued progress towards the understanding of basic solar phenomena by further efforts in this direction is promising

  4. Western Pond Turtle Observations - Region 1 [ds313

    California Department of Resources — This dataset was developed in an effort to compile Western Pond Turtle (Clemmys marmorata) observations in CDFG Region 1. Steve Burton (CDFG Staff Environmental...

  5. Cool transition region loops observed by the Interface Region Imaging Spectrograph

    Huang, Zhenghua; Li, Bo; Madjarska, Maria S

    2015-01-01

    We report on the first Interface Region Imaging Spectrograph (IRIS) study of cool transition region loops. This class of loops has received little attention in the literature. A cluster of such loops was observed on the solar disk in active region NOAA11934, in the Si IV 1402.8 \\AA\\ spectral raster and 1400 \\AA\\ slit-jaw (SJ) images. We divide the loops into three groups and study their dynamics and interaction. The first group comprises relatively stable loops, with 382--626\\,km cross-sections. Observed Doppler velocities are suggestive of siphon flows, gradually changing from -10 km/s at one end to 20 km/s at the other end of the loops. Nonthermal velocities from 15 to 25 km/s were determined. These physical properties suggest that these loops are impulsively heated by magnetic reconnection occurring at the blue-shifted footpoints where magnetic cancellation with a rate of $10^{15}$ Mx/s is found. The released magnetic energy is redistributed by the siphon flows. The second group corresponds to two footpoin...

  6. Entrepreneurship, Innovation Activities and Regional Growth

    Aikaterini KOKKINOU

    2005-01-01

    There is a huge literature for the role and the implications of entrepreneurship on innovation activities and economic growth, through 'regional systems of innovation'. This paper attempts to define the main determinant factors of entrepreneurial and innovation activities. In particular, the paper attempts to analyze, using an econometric approach, the effects of entrepreneurship on innovation activities and furthermore to clarify the implication on regional system of innovation, competitiven...

  7. Thermal cyclotron radiation from solar active regions

    Various frequency spectra with the fine structure resulting from the thermal cyclotron radio emission from solar active regions are discussed. The conditions in sources (distribution of magnetic field and kinetic temperature over the height) are put forward which provide the frequency spectrum as a set of cyclotron lines and high frequency cut-offs. For each kind of distribution the frequency spectrum and polarization are of peculiar character. This permits one to find the conditions in the source through the properties of the observed microwave solar radio emission. To obtain reliable data on the fine structure and judge about conditions in the sources it is necessary to study microwave solar radio emission using the swept-frequency or multi-channel receivers combined with high directional antennae. (Auth.)

  8. The coronal structure of active regions

    A four-parameter model which assumes a Gaussian dependence of both temperature and pressure on distance from center is used to fit the compact part of coronal active regions as observed in X-ray photographs from a rocket experiment. The four parameters are the maximum temperature Tsub(M), the maximum pressure Psub(M)=2Nsub(M)kTsub(M), the width of the pressure distribution sigmasub(P), and the width of the temperature distribution sigmasub(T)=αsup(1/2)sigmasub(P). The maximum temperature Tsub(M) ranges from 2.2 to 2.8x106K, and the maximum density Nsub(M) from 2 to 9x109cm-3. The range of sigmasub(P) is from 2 to 4x109 cm and that of α from 2 to 7. (Auth.)

  9. Image patch analysis of sunspots and active regions

    Moon Kevin R.

    2016-01-01

    Full Text Available Context. Separating active regions that are quiet from potentially eruptive ones is a key issue in Space Weather applications. Traditional classification schemes such as Mount Wilson and McIntosh have been effective in relating an active region large scale magnetic configuration to its ability to produce eruptive events. However, their qualitative nature prevents systematic studies of an active region’s evolution for example. Aims. We introduce a new clustering of active regions that is based on the local geometry observed in Line of Sight magnetogram and continuum images. Methods. We use a reduced-dimension representation of an active region that is obtained by factoring the corresponding data matrix comprised of local image patches. Two factorizations can be compared via the definition of appropriate metrics on the resulting factors. The distances obtained from these metrics are then used to cluster the active regions. Results. We find that these metrics result in natural clusterings of active regions. The clusterings are related to large scale descriptors of an active region such as its size, its local magnetic field distribution, and its complexity as measured by the Mount Wilson classification scheme. We also find that including data focused on the neutral line of an active region can result in an increased correspondence between our clustering results and other active region descriptors such as the Mount Wilson classifications and the R-value. Conclusions. Matrix factorization of image patches is a promising new way of characterizing active regions. We provide some recommendations for which metrics, matrix factorization techniques, and regions of interest to use to study active regions.

  10. A paradigm shift in stormflow predictions for active tectonic regions with large-magnitude storms: generalisation of catchment observations by hydraulic sensitivity analysis and insight into soil-layer evolution

    Tani, Makoto

    2013-11-01

    In active tectonic regions with large-magnitude storms, it is still difficult to predict stormflow responses by distributed runoff models from the catchment properties without a parameter calibration using observational data. This paper represents an attempt to address the problem. A review of observational studies showed that the stormflow generation mechanism was heterogeneous and complex, but stormflow responses there were simply simulated by a single tank with a drainage hole when the stormflow-contribution area was spatially invariable due to the sufficient amount of rainfall supply. These results suggested such a quick inflow/outflow waveform transmission was derived from the creation of a hydraulic continuum under a quasi-steady state. General conditions necessary for the continuum creation were theoretically examined by a sensitivity analysis for a sloping soil layer. A new similarity framework using the Richards equation was developed for specifying the sensitivities of waveform transmission to topographic and soil properties. The sensitivity analysis showed that saturation-excess overland flow was generally produced from a soil layer without any macropore effect, whereas the transmission was derived mainly from the vertical unsaturated flow instead of the downslope flow in a soil layer with a large drainage capacity originated from the macropore effect. Both were possible for the quick transmission, but a discussion on the soil-layer evolution process suggested that an inhibition of the overland flow due to a large drainage capacity played a key role, because a confinement of the water flow within the soil layer might be needed for the evolution against strong erosional forces in the geographical regions. The long history of its evolution may mediate a relationship between simple stormflow responses and complex catchment properties. As a result, an insight into this evolution process and an inductive evaluation of the dependences on catchment properties

  11. Evaluating Observation Influence on Regional Water Budgets in Reanalyses

    Bosilovich, Michael G.; Chern, Jiun-Dar; Mocko, David; Robertson, Franklin R.; daSilva, Arlindo M.

    2014-01-01

    The assimilation of observations in reanalyses incurs the potential for the physical terms of budgets to be balanced by a term relating the fit of the observations relative to a forecast first guess analysis. This may indicate a limitation in the physical processes of the background model, or perhaps inconsistencies in the observing system and its assimilation. In the MERRA reanalysis, an area of long term moisture flux divergence over land has been identified over the Central United States. Here, we evaluate the water vapor budget in this region, taking advantage of two unique features of the MERRA diagnostic output; 1) a closed water budget that includes the analysis increment and 2) a gridded diagnostic output data set of the assimilated observations and their innovations (e.g. forecast departures). In the Central United States, an anomaly occurs where the analysis adds water to the region, while precipitation decreases and moisture flux divergence increases. This is related more to a change in the observing system than to a deficiency in the model physical processes. MERRAs Gridded Innovations and Observations (GIO) data narrow the observations that influence this feature to the ATOVS and Aqua satellites during the 06Z and 18Z analysis cycles. Observing system experiments further narrow the instruments that affect the anomalous feature to AMSUA (mainly window channels) and AIRS. This effort also shows the complexities of the observing system, and the reactions of the regional water budgets in reanalyses to the assimilated observations.

  12. The Horizontal Photospheric Flows During the Emergence of Active Regions

    Khlystova, A

    2012-01-01

    The dynamics of horizontal plasma flows during the first hours of the emergence of active region magnetic fields in the solar photosphere have been analyzed using SOHO/MDI data. Four active regions emerging near the solar limb have been considered. It has been found that extended regions with different signs of velocity are formed in the first hours of the emergence of magnetic fields in the horizontal velocity field. The flows observed are directly connected with the emergence of the magnetic flux of active regions. They form at the beginning of the appearance of magnetic fields and are present for a few hours. Velocity structures situated in the region of leading magnetic poles are more powerful and exist longer than those in the following ones. The Doppler velocity values exceed substantially the separation velocity of the outer boundaries of the photospheric magnetic flux. The interpretation of the observable flow of photospheric plasma is given.

  13. Regional characteristics, opportunity perception and entrepreneurial activities

    Stuetzer, Michael; Obschonka, Martin; Brixy, Udo; Sternberg, Rolf; Cantner, Uwe

    2013-01-01

    This paper seeks to better understand the link between regional characteristics and individual entrepreneurship. We combine individual-level GEM data for Western Germany with regional-level data, using multi-level analysis to test our hypotheses. We find no direct link between regional knowledge creation, the economic context and an entrepreneurial culture on the one side and individual business start-up intentions and start-up activity on the other side. However our findings point to the imp...

  14. 3-D reconstructions of active stars - observations

    Korhonen, Heidi

    2012-01-01

    Stars are usually faint point sources and investigating their surfaces and interiors observationally is very demanding. Here I give a review on the state-of-the-art observing techniques and recent results on studying interiors and surface features of active stars.

  15. Kink waves in an active region dynamic fibril

    Pietarila, A; Hirzberger, J; Solanki, S K

    2011-01-01

    We present high spatial and temporal resolution Ca II 8542 observations of a kink wave in an on-disk chromospheric active region fibril. The properties of the wave are similar to those observed in off-limb spicules. From the observed phase and period of the wave we determine a lower limit for the field strength in the chromospheric active region fibril located at the edge of a sunspot to be a few hundred Gauss. We find indications that the event was triggered by a small-scale reconnection event higher up in the atmosphere.

  16. The Built Environment Predicts Observed Physical Activity

    Kelly, Cheryl; Wilson, Jeffrey S.; Schootman, Mario; Clennin, Morgan; Baker, Elizabeth A.; Miller, Douglas K.

    2014-01-01

    Background: In order to improve our understanding of the relationship between the built environment and physical activity, it is important to identify associations between specific geographic characteristics and physical activity behaviors. Purpose: Examine relationships between observed physical activity behavior and measures of the built environment collected on 291 street segments in Indianapolis and St. Louis. Methods: Street segments were selected using a stratified geographic samp...

  17. 7 mm continuum observations of ultra compact HII regions

    Leto, P.; Umana, G.; Trigilio, C.; Buemi, C. S.; Dolei, S.; Manzitto, P.; L. Cerrigone; Siringo, C.

    2009-01-01

    Ultra compact HII (UCHII) regions are indicators of high-mass star formation sites and are distributed mainly in the Galactic plane. We intend to investigate the possible contribution of the forthcoming ESA Planck mission to the science of UCHII regions by evaluating the possibility of detecting UCHIIs that are bright in the radio regime. We performed new 7 mm observations of a sample of UCHII regions. For each source in our sample, the free-free radio spectrum has been modeled. Along with fa...

  18. Lidar Observation of Tropopause Ozone Profiles in the Equatorial Region

    Shibata, Yasukuni; Nagasawa, Chikao; Abo, Makoto

    2016-06-01

    Tropospheric ozone in the tropics zone is significant in terms of the oxidizing efficiency and greenhouse effect. However, in the upper troposphere, the ozone budget in the tropics has not been fully understood yet because of the sparsity of the range-resolved observations of vertical ozone concentration profiles. A DIAL (differential absorption lidar) system for vertical ozone profiles have been installed in the equatorial tropopause region over Kototabang, Indonesia (100.3E, 0.2S). We have observed large ozone enhancement in the upper troposphere, altitude of 13 - 17 km, concurring with a zonal wind oscillation associated with the equatorial Kelvin wave around the tropopause at equatorial region.

  19. Patterns of Activity in a Global Model of a Solar Active Region

    Bradshaw, S. J.; Viall, N. M.

    2016-04-01

    In this work we investigate the global activity patterns predicted from a model active region heated by distributions of nanoflares that have a range of frequencies. What differs is the average frequency of the distributions. The activity patterns are manifested in time lag maps of narrow-band instrument channel pairs. We combine hydrodynamic and forward modeling codes with a magnetic field extrapolation to create a model active region and apply the time lag method to synthetic observations. Our aim is not to reproduce a particular set of observations in detail, but to recover some typical properties and patterns observed in active regions. Our key findings are the following. (1) Cooling dominates the time lag signature and the time lags between the channel pairs are generally consistent with observed values. (2) Shorter coronal loops in the core cool more quickly than longer loops at the periphery. (3) All channel pairs show zero time lag when the line of sight passes through coronal loop footpoints. (4) There is strong evidence that plasma must be re-energized on a timescale comparable to the cooling timescale to reproduce the observed coronal activity, but it is likely that a relatively broad spectrum of heating frequencies are operating across active regions. (5) Due to their highly dynamic nature, we find nanoflare trains produce zero time lags along entire flux tubes in our model active region that are seen between the same channel pairs in observed active regions.

  20. A Regional CO2 Observing System Simulation Experiment Using ASCENDS Observations and WRF-STILT Footprints

    Wang, James S.; Kawa, S. Randolph; Eluszkiewicz, Janusz; Collatz, G. J.; Mountain, Marikate; Henderson, John; Nehrkorn, Thomas; Aschbrenner, Ryan; Zaccheo, T. Scott

    2012-01-01

    Knowledge of the spatiotemporal variations in emissions and uptake of CO2 is hampered by sparse measurements. The recent advent of satellite measurements of CO2 concentrations is increasing the density of measurements, and the future mission ASCENDS (Active Sensing of CO2 Emissions over Nights, Days and Seasons) will provide even greater coverage and precision. Lagrangian atmospheric transport models run backward in time can quantify surface influences ("footprints") of diverse measurement platforms and are particularly well suited for inverse estimation of regional surface CO2 fluxes at high resolution based on satellite observations. We utilize the STILT Lagrangian particle dispersion model, driven by WRF meteorological fields at 40-km resolution, in a Bayesian synthesis inversion approach to quantify the ability of ASCENDS column CO2 observations to constrain fluxes at high resolution. This study focuses on land-based biospheric fluxes, whose uncertainties are especially large, in a domain encompassing North America. We present results based on realistic input fields for 2007. Pseudo-observation random errors are estimated from backscatter and optical depth measured by the CALIPSO satellite. We estimate a priori flux uncertainties based on output from the CASA-GFED (v.3) biosphere model and make simple assumptions about spatial and temporal error correlations. WRF-STILT footprints are convolved with candidate vertical weighting functions for ASCENDS. We find that at a horizontal flux resolution of 1 degree x 1 degree, ASCENDS observations are potentially able to reduce average weekly flux uncertainties by 0-8% in July, and 0-0.5% in January (assuming an error of 0.5 ppm at the Railroad Valley reference site). Aggregated to coarser resolutions, e.g. 5 degrees x 5 degrees, the uncertainty reductions are larger and more similar to those estimated in previous satellite data observing system simulation experiments.

  1. Observations of ammonia in galactic H II regions

    Vilas Boas, J. W. S.; Scalise, E., Jr.; Monteiro Do Vale, J. L.

    1988-02-01

    This paper presents the first results for the (J,K) = (1,1) and (2,2) ammonia transitions observed in the direction of some southern galactic H II regions, selected among the strongest H2CO emitters. Some physical parameters derived for each individual source, including several new sources of ammonia lines, are presented.

  2. DISTRIBUTION OF ELECTRIC CURRENTS IN SOLAR ACTIVE REGIONS

    There has been a long-standing debate on the question of whether or not electric currents in solar active regions are neutralized. That is, whether or not the main (or direct) coronal currents connecting the active region polarities are surrounded by shielding (or return) currents of equal total value and opposite direction. Both theory and observations are not yet fully conclusive regarding this question, and numerical simulations have, surprisingly, barely been used to address it. Here we quantify the evolution of electric currents during the formation of a bipolar active region by considering a three-dimensional magnetohydrodynamic simulation of the emergence of a sub-photospheric, current-neutralized magnetic flux rope into the solar atmosphere. We find that a strong deviation from current neutralization develops simultaneously with the onset of significant flux emergence into the corona, accompanied by the development of substantial magnetic shear along the active region's polarity inversion line. After the region has formed and flux emergence has ceased, the strong magnetic fields in the region's center are connected solely by direct currents, and the total direct current is several times larger than the total return current. These results suggest that active regions, the main sources of coronal mass ejections and flares, are born with substantial net currents, in agreement with recent observations. Furthermore, they support eruption models that employ pre-eruption magnetic fields containing such currents

  3. Regional characteristics, opportunity perception and entrepreneurial activities

    Stuetzer, Michael; Obschonka, Martin; Brixy, Udo;

    2014-01-01

    This article seeks to better understand the link between regional characteristics and individual entrepreneurship. We combine individual-level Global Entrepreneurship Monitor data for Western Germany with regional-level data, using multilevel analysis to test our hypotheses. We find no direct lin...... creation, the economic context and an entrepreneurial culture have an effect on the individual perception of founding opportunities, which in turn predicted start-up intentions and activity. © 2013 Springer Science+Business Media New York....

  4. Solar active regions: a nonparametric statistical analysis

    Pelt, J; Tuominen, I

    2009-01-01

    The sunspots and other solar activity indicators tend to cluster on the surface of the Sun.These clusters very often occur at certain longitudes that persist in time.It is of general interest to find new and simple ways to characterize the observed distributions of different indicators and their behaviour in time. In the present work we use Greenwich sunspot data to evaluate statistical but not totally coherent stability of sunspot distribution along latitudes as well as longitudes. The aim was to obtain information on the longitudinal distribution of the underlying spot-generating mechanism rather than on the distribution and migration of sunspots or sunspot groups on the solar surface. Therefore only sunspot groups were included in the analysis, and only the time of their first appearance was used. We use simple nonparametric approach to reveal sunspot migration patterns and their persistency. Our analysis shows that regions where spots are generated tend to rotate differentially as the spots and spot group...

  5. DEFPOS H α observations of H II regions

    Aksaker, N.; Sahan, M.; Yegingil, I.; Emrahoglu, N.

    2011-12-01

    We present H α emission line measurements of northern bright H II regions selected from the Sharpless (1959) catalog near the Galactic plane ( b ⩽ ± 6°). A total of 10 H II regions were observed with DEFPOS (Dual Etalon Fabry-Perot Optical Spectrometer) system at the f/48 Coude focus of 150 cm RTT150 telescope located at TUBITAK National Observatory (TUG) in Antalya/Turkey. The intensities, the local standard of rest (LSR) velocities ( VLSR), and the linewidths (Full Width Half Maximum: FWHM) of the H α emission line from our observations were in the range of 84 to 745 Rayleigh ( R [one Rayleigh ( R) is 10 6/4 π photons cm -2 sr -1 s -1 = 2.4110 -7 erg cm -2 sr -1 s -1 at H α and corresponds to an emission measure (EM=∫ne2dl) of 2.3 pc cm -6 for a gas temperature of 8000 K, where ne is the averaged electron density within an emitting region in the interstellar medium; dl is distance element to the source region ( Haffner et al., 2003; Reynolds et al., 2005), 3 to -43 km s -1 and 30 to 73 km s -1, respectively. The LSR velocities and the linewidths from the data were obtained and compared with early results. We found that our results are in close agreement with them. Moreover, associated stars of some of the H II regions were updated by analyzing their location, velocities, and brightness.

  6. Photospheric Magnetic Free Energy Density of Solar Active Regions

    Zhang, Hongqi

    2016-01-01

    We present the photospheric energy density of magnetic fields in two solar active regions inferred from observational vector magnetograms, and compare it with the possible different defined energy parameters of magnetic fields in the photosphere. We analyze the magnetic fields in active region NOAA 6580-6619-6659 and 11158. It is noticed that the quantity 1/4pi Bn.Bp is an important energy parameter that reflects the contribution of magnetic shear on the difference between the potential magnetic field (Bp) and non-potential one (Bn), and also the contribution to the free magnetic energy near the magnetic neutral lines in the active regions. It is found that the photospheric mean magnetic energy density changes obviously before the powerful solar flares in the active region NOAA 11158, it is consistent with the change of magnetic fields in the lower atmosphere with flares.

  7. Distribution of Electric Currents in Solar Active Regions

    Török, Tibor; Titov, Viacheslav S; Archontis, Vasilis; Mikić, Zoran; Linton, Mark G; Dalmasse, Kévin; Aulanier, Guillaume; Kliem, Bernhard

    2014-01-01

    There has been a long-lasting debate on the question of whether or not electric currents in solar active regions are neutralized. That is, whether or not the main (or direct) coronal currents connecting the active region polarities are surrounded by shielding (or return) currents of equal total value and opposite direction. Both theory and observations are not yet fully conclusive regarding this question, and numerical simulations have, surprisingly, barely been used to address it. Here we quantify the evolution of electric currents during the formation of a bipolar active region by considering a three-dimensional magnetohydrodynamic simulation of the emergence of a sub-photospheric, current-neutralized magnetic flux rope into the solar atmosphere. We find that a strong deviation from current neutralization develops simultaneously with the onset of significant flux emergence into the corona, accompanied by the development of substantial magnetic shear along the active region's polarity inversion line. After t...

  8. Two Years of Regional Cabled Seafloor Observations Across Northern Cascadia

    Moran, K.; Juniper, K.; Heesemann, M.; Hoeberechts, M.; Matabos, M.; Mihaly, S.; Scherwath, M.

    2012-04-01

    NEPTUNE Canada completed the installation and is now operating an 800 km, regional cabled ocean network that spans the northern Juan de Fuca tectonic plate and continental shelf/slope in the northeastern Pacific. The NEPTUNE Canada network is part of the Ocean Networks Canada Observatory. Public data flow started in 2009 and interactive instruments continue to be added to this technically advanced system which provides continuous power and high bandwidth for enabling the collection of real-time physical, chemical, geological, and biological oceanographic data at resolutions relevant for furthering our understanding of the dynamics of the earth-ocean system. Recent results at five NEPTUNE nodes are presented. Inshore at Folger Passage and Barkley Sound experiments focus on understanding biological productivity and the effects that marine processes have on fish and marine mammals. Experiments further offshore at Barkley Canyon allow quantification of changes in benthic activity with nutrient and sediment transport. Barkley Canyon and further north along the mid-continental slope near ODP Site 889, instruments are monitoring changes in the distribution, structure, related biotas and venting of gas hydrates. A Circulation Obviation Retrofit Kit (CORK) at our mid-plate site (ODP 1027) monitors crustal temperature and pressure, particularly related to triggered events, such as earthquakes, tsunamis, hydrothermal convection. On the Juan de Fuca Ridge, the Endeavour node observes volcanic, tectonic, hydrothermal, and associated biological processes. NEPTUNE Canada provides high resolution acoustic and seismic monitoring across the entire network, important for understanding subduction earthquake processes and contributing to a near-field tsunami detection system. An array of bottom pressure recorders is used for the determination of trans-Pacific open ocean tsunami amplitude, propagation direction, and as model input to examine tsunami interaction with the complex coast

  9. Cluster observations of particle acceleration up to supra-thermal energies in the cusp region related to low-frequency wave activity – possible implications for the substorm initiation process

    T. A. Fritz

    2008-03-01

    Full Text Available The purpose of our study is to investigate the way particles are accelerated up to supra-thermal energies in the cusp diamagnetic cavities. For this reason we have examined a number of Cluster cusp crossings, originally identified by Zhang et al. (2005, for the years 2001 and 2002 using data from RAPID, STAFF, EFW, CIS, PEACE, and FGM experiments. In the present study we focus on two particular cusp crossings on 25 March 2002 and on 10 April 2002 which demonstrate in a clear way the general characteristics of the events in our survey. Both events exhibit very sharp spatial boundaries seen both in CNO (primarily single-charged oxygen of ionospheric origin based on CIS observations and H+ flux increases within the RAPID energy range with the magnetic field intensity being anti-correlated. Unlike the first event, the second one shows also a moderate electron flux increase. The fact that the duskward electric field Ey has relatively low values <5 mV/m while the local wave activity is very intense provides a strong indication that particle energization is caused primarily by wave-particle interactions. The wave power spectra and propagation parameters during these cusp events are examined in detail. It is concluded that the high ion fluxes and at the same time the presence or absence of any sign of energization in the electrons clearly shows that the particle acceleration depends on the wave power near the local particle gyrofrequency and on the persistence of the wave-particle interaction process before particles escape from cusp region. Furthermore, the continuous existence of energetic O+ ions suggests that energetic O+ populations are of spatial nature at least for the eight events that we have studied so far.

  10. Radio observations of the HII region complex RCW 95

    Barres de Almeida, U.; Abraham, Z.; Roman-Lopes, A.

    The cloud RCW 95 was selected for study along with a number of other southern hemisphere regions in the galactic plane as part of a large program of search for YSOs associated with molecular clouds in the Galaxy. The project is an example of successful exploitation of large galactic surveys and combined both radio and far-IR observations. The selection of objects for study was based on data from the IRAS point source catalogue, in which we looked for sources with properties characteristic of star formation regions (SFRs). The main criteria constituted the presence of IRAS colours characteristic of compact HII regions, as according to work by Wood and Churchwell (1989) and the association with strong CS emission (using data from the catalogue of Bronfman et al. 1996). The presence of different maser species, typically found in association with SFRs, and ammonia lines was also used as an auxiliary information in the process. After selection, the stellar population of the regions were studied in the near-IR using data from both the 2MASS project and the SPTIZER satellite, allowing the construction of complete near-IR SEDs of the stars. RCW 95 is a special example of a region where the search successfully resulted in the discovery of several rich sites of star formation (Roman-Lopes and Abraham 2004 and 2006) and so, more detailed observations of the cloud were performed in radio in order to adress the structure and distribution of the compact HII regions therein. The continuum emission of the cloud was mapped in 43 GHz with a resolution of 2' and a complete water maser survey was conducted in its direction, at 22.2 GHz, with a positional accuracy of 1'; the result of these observations was a more clear picture of the structure of the compact and ultra-compact HII regions within the cloud and the discovery of more sites of star-formation that are still too obscured to be directly detected in the far-IR. In particular, the IRAS source 15412-5359 was revealed to be a

  11. Enhancing Earth Observation Capacity in the Himalayan Region

    Shrestha, B. R.

    2012-12-01

    Earth observations bear special significance in the Himalayan Region owing to the fact that routine data collections are often hampered by highly inaccessible terrain and harsh climatic conditions. The ongoing rapid environmental changes have further emphasized its relevance and use for informed decision-making. The International Center for Integrated Mountain Development (ICIMOD), with a regional mandate is promoting the use of earth observations in line with the GEOSS societal benefit areas. ICIMOD has a proven track record to utilize earth observations notably in the areas of understanding glaciers and snow dynamics, disaster risk preparedness and emergency response, carbon estimation for community forestry user groups, land cover change assessment, agriculture monitoring and food security analysis among others. This paper presents the challenges and lessons learned as a part of capacity building of ICIMOD to utilize earth observations with the primary objectives to empower its member countries and foster regional cooperation. As a part of capacity building, ICIMOD continues to make its efforts to augment as a regional resource center on earth observation and geospatial applications for sustainable mountain development. Capacity building possesses multitude of challenges in the region: the complex geo-political reality with differentiated capacities of member states, poorer institutional and technical infrastructure; addressing the needs for multiple user and target groups; integration with different thematic disciplines; and high resources intensity and sustainability. A capacity building framework was developed based on detailed needs assessment with a regional approach and strategy to enhance capability of ICIMOD and its network of national partners. A specialized one-week training course and curriculum have been designed for different thematic areas to impart knowledge and skills that include development practitioners, professionals, researchers and

  12. Twin mesospheric bores observed over Brazilian equatorial region

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

    2016-01-01

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

  13. Radio Observations Of The HII Region Complex RCW 95

    Barres de Almeida, U.; Abraham, Z.; Roman-Lopes, A.

    2006-08-01

    In this work we studied the complex of compact HII regions RCW 95. The cloud was mapped on the radio continuum emission at 43 GHz; a survey of water lines was also conducted at 22 GHz. The observations were made with the 14-meter single-dish antennae of the Itapetinga radio observatory in Brazil, with 2' resolution at 43 GHz. For the continuum observations we made several scans in right ascension throughout the whole of the source spaced by 1' in declination, and with 45' extension in RA to allow for baseline correction. The study resulted on the identification of resolved radio continuum sources associated with all the three IRAS sources in the region: IRAS 15408-5356, 15411-5352 and 15412-5359, all with far-IR colours characteristics of CHII regions. The water line survey resulted on the positive identification of maser emission associated with the three IRAS sources, supporting the evidences for these regions to harbour massive young stars. Two other unresolved HII regions, not associated with far-IR sources, were also discovered through detailed analysis of the profiles of the radio continuum scans. Whilst the stellar content of the IRAS sources 15408-5356 and 15411-5352 have been previously studied in the near-IR (Roman-Lopes & Abraham 2004 and 2006), the stellar population associated to IRAS 15412-5359 was first studied in the near and middle-IR by us, motivated by the results obtained in radio. We used photometric data from 1 to 8 μm from 2MASS and SPITZER and identified a significant population of massive stars, including one O9V and some early-BV stars, that explain the ionization of the source.

  14. Dynamic properties of bright points in an active region

    Keys, Peter H; Jess, David B; Mackay, Duncan H; Keenan, Francis P

    2014-01-01

    Context. Bright points (BPs) are small-scale, magnetic features ubiquitous across the solar surface. Previously, we have observed and noted their properties for quiet Sun regions. Here, we determine the dynamic properties of BPs using simultaneous quiet Sun and active region data. Methods. High spatial and temporal resolution G-band observations of active region AR11372 were obtained with the Rapid Oscillations in the Solar Atmosphere instrument at the Dunn Solar Telescope. Three subfields of varying polarity and magnetic flux density were selected with the aid of magnetograms obtained from the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory. Bright points within these subfields were subsequently tracked and analysed. Results. It is found that BPs within active regions display attenuated velocity distributions with an average horizontal velocity of ~0.6 km/s, compared to the quiet region which had an average velocity of 0.9 km/s. Active region BPs are also ~21% larger than quiet regio...

  15. Infrared Photometry of Solar Active Regions

    Μ. Sobotka; Μ. V'azquez; Μ. S'anchez Cuberes; J. A. Bonet; A. Hanslmeier

    2000-09-01

    Simultaneous time series of broad-band images of two active regions close to the disk center were acquired at the maximum (0.80 m) and minimum (1.55 m) continuum opacities. Dark faculae are detected in images obtained as weighted intensity differences between both wave-length bands. The elements of quiet regions can be clearly distinguished from those of faculae and pores in scatter plots of brightness temperatures. There is a smooth transition between faculae and pores in the scatter plots. These facts are interpreted in terms of the balance between the inhibition of convective energy transport and the lateral radiative heating.

  16. Diffuse Far-ultraviolet Observation of the Lupus Loop Region

    Shinn, J H; Han, W; Jin, H; Korpela, E J; Lee, C N; Lee, D H; Min, K W; Nam, U W; Welsh, B Y; Edelstein, Jerry; Han, Wonyong; Jin, Ho; Korpela, Eric J.; Lee, Chi-Na; Lee, Dae-Hee; Min, Kyoung Wook; Nam, Uk-Won; Shinn, Jong-Ho; Welsh, Barry Y.

    2006-01-01

    Diffuse far-ultraviolet (FUV) emissions from the Lupus Loop region (SNR 330.0+15.0) have been observed with Spectroscopy of Plasma Evolution from Astrophysical Radiation (SPEAR), also known as Far-ultraviolet IMaging Spectrograph (FIMS). We have detected several important ionic lines, including Si II*, C IV, and N IV], which characterize the warm, hot ionized gas in this region. The spatial variations in the line intensities of Si II* and C IV have also been studied in comparison with X-ray and dust observations. The result shows that they originate from the interface between the hot gas seen in the X-ray and the cooler H I shell with which dust is associated. The interface is rather diffuse, and the gases with different temperatures seem to co-exist in this region. A shock may exist upfront in the interface, but its velocity should be very small as no shock-related distinguished feature is seen in Ha.

  17. The Magnetic Classification of Solar Active Regions 1992 - 2015

    Jaeggli, Sarah A

    2016-01-01

    The purpose of this letter is to address a blind-spot in our knowledge of solar active region statistics. To the best of our knowledge there are no published results showing the variation of the Mount Wilson magnetic classifications as a function of solar cycle based on modern observations. We show statistics for all active regions reported in the daily Solar Region Summary from 1992 January 1 to 2015 December 31. We find that the $\\alpha$ and $\\beta$ class active regions (including all sub-groups e.g. $\\beta\\gamma$, $\\beta\\delta$) make up fractions of approximately 20% and 80% of the sample respectively. This fraction is relatively constant during high levels of activity, however, an increase in the $\\alpha$ fraction to about 35% and and a decrease in the $\\beta$ fraction to about 65% can be seen near each solar minimum and is statistically significant at the 2-$\\sigma$ level. Over 30% of all active regions observed during the years of solar maxima were appended with the classifications $\\gamma$ and/or $\\del...

  18. Determinants of Foreign Technological Activity in German Regions

    Dettmann, Eva; Lacasa, Iciar Dominguez; Günther, Jutta; Jindra, Björn

    This paper analyses the determinants of spatial distribution of foreign technological activity across 96 German regions (1996-2009). We identify foreign inventive activity by applying the ‘cross-border-ownership concept’ to transnational patent applications. The descriptive analysis shows that fo...... non-linear and that it is influenced by sectoral heterogeneity. Externalities related to technological diversification attract foreign R&D only into ‘higher order’ regions....... foreign technological activity more than doubled during the observation period with persistent spatial heterogeneity in Germany. Using a pooled count data model, we estimate the effect of various sources for externalities on the extent of foreign technological activity across regions. Our results show...

  19. Region-dependent seasonal pattern of methane over Indian region as observed by SCIAMACHY

    Kavitha, M.; Nair, Prabha R.

    2016-04-01

    The column averaged mixing ratio of methane (XCH4) from SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) on-board satellite ENVISAT has been used to study its regional pattern and seasonal cycle over Indian region for the period 2003-2009. XCH4 varies from 1740 to 1890 ppbv over Indian region with distinct spatial and temporal features. The peak values are observed in monsoon and post monsoon and minimum in winter months, except over southern Peninsular India which shows the distinctly different seasonal behavior with peak in October/November. The mean background level of XCH4 over Indian region is estimated as ∼1795 ppbv. While regional patterns are strongly associated with livestock distribution, wetland emissions, including rice fields, the seasonal variations in XCH4 are predominantly associated with the rice cultivation as revealed by analysis of NDVI.

  20. Radio observations of the CMa OB1 H II regions

    A sensitive 100 x 150 13-cm map made of the CMa OB1 H II regions' radio emission shows a strong similarity to Hα emission photographs. Sharpless 296 is shown to consist of a prominent central and western arc completed by a weaker southern loop, and with a faint northern bar. The emission is thermal, superimposed over a predominantly non-thermal background. The H142α recombination line has been detected at eight positions in S296, and in S292 and S297. The average electron temperature in S296 is 6900 +- 1300 K. The UV fluxes from the CMa OB1 stars account for the observed emission measures of the H II regions. The H142α 1sr velocities indicate that the ionized material is in contact with the molecular clouds. (author)

  1. A submllimeter observation and study of star-forming regions

    2002-01-01

    Using the 3-m radio telescope of KOSMA, we mapped 12CO (J = 3-2) lines for three molecular clouds, B35, S146 and TMC-2A. High-velocity molecular outflows are found in all these regions. The physical and dynamical parameters of the outflows are derived, and their shapes and driving sources are analyzed. Contour maps of center velocities show that the large scale systematic gradients exist in the three clouds. These observed motions are best explained by rotation after excluding the cause of outflows. Furthermore, in the core region of TMC-2A there is a velocity gradient in opposite direction from that of the large scale. It may be caused by magnetic braking. Finally, angular velocities of the clouds are calculated, and the effects of rotation against gravity and lowering the star-formation rate are also analyzed.

  2. Regional brain activity correlates of nicotine dependence.

    Rose, Jed E; Behm, Frederique M; Salley, Alfred N; Bates, James E; Coleman, R Edward; Hawk, Thomas C; Turkington, Timothy G

    2007-12-01

    Fifteen smokers participated in a study investigating brain correlates of nicotine dependence. Dependence was reduced by having subjects switch to denicotinized cigarettes for 2 weeks while wearing nicotine skin patches. Positron emission tomography (PET) scans assessed regional cerebral metabolic rate for glucose (rCMRglc) after overnight nicotine abstinence on three occasions: (1) at baseline; (2) after 2 weeks of exposure to denicotinized cigarettes+nicotine patches; and (3) 2 weeks after returning to smoking the usual brands of cigarettes. Craving for cigarettes and scores on the Fagerström Test of Nicotine Dependence (FTND) questionnaire decreased at the second session relative to the first and last sessions. Regional brain metabolic activity (normalized to whole brain values) at session 2 also showed a significant decrease in the right hemisphere anterior cingulate cortex. Exploratory post hoc analyses showed that the change in craving across sessions was negatively correlated with the change in rCMRglc in several structures within the brain reward system, including the ventral striatum, orbitofrontal cortex and pons. The between-session difference in thalamus activity (right hemisphere) was positively correlated with the difference in FTND scores. Correlational analyses also revealed that reported smoking for calming effects was associated with a decrease (at session 2) in thalamus activity (bilaterally) and with an increase in amygdala activity (left hemisphere). Reported smoking to enhance pleasurable relaxation was associated with an increase in metabolic activity of the dorsal striatum (caudate, putamen) at session 2. These findings suggest that reversible changes in regional brain metabolic activity occur in conjunction with alterations in nicotine dependence. The results also highlight the likely role of thalamic gating processes as well as striatal reward and corticolimbic regulatory pathways in the maintenance of cigarette addiction. PMID:17356570

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

    Shibasaki, K.

    2011-12-01

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

  4. Emission line regions of active galactic nuclei and quasars

    The observational constraints on the conditions in the gas which give rise to the emission lines seen in the spectra of quasars and active galactic nuclei are summarized, with particular attention being paid to the region responsible for the broad lines. Some general requirements on the physical conditions and geometry are described, and the emission line region of the quasar 3C273 is used to illustrate the successes, and shortcomings, of photoionization models. Comparisons of the emission line profiles of different ions show that there must be some radial flow, and obscuration, in the region of the emission line material

  5. Galileo SSI Observations of Volcanic Activity at Tvashtar Catena, Io

    Milazzo, M. P.; Keszthely, L. P.; Radebaugh, J.; Davies, A. G.; Turtle, E. P.; Geissler, P.; Klaasen, K. P.; McEwen, A. S.

    2005-01-01

    Introduction: We report on the analysis of the Galileo SSI's observations of the volcanic activity at Tvashtar Catena, Io as discussed by Milazzo et al. Galileo's Solid State Imager (SSI) observed Tvashtar Catena (63 deg N, 120 deg W) four times between November 1999 and October 2001, providing a unique look at the distinctive high latitude volcanism on Io. The November 1999 observation spatially resolved, for the first time, an active extraterrestrial fissure eruption. The brightness temperature of the lavas at the November 1999 fissure eruption was 1300 K. The second observation (orbit I27, February 2000) showed a large (approx. 500 sq km) region with many, small spots of hot, active lava. The third observation was taken in conjunction with a Cassini observation in December 2000 and showed a Pele-like plume deposition ring, while the Cassini images revealed a 400 km high Pele-type plume above the Catena. The final Galileo SSI observation of Tvashtar was acquired in October 2001, and all obvious (to SSI) activity had ceased, although data from Galileo's Near Infrared Mapping Spectrometer (NIMS) indicated that there was still significant thermal emission from the Tvashtar region. We have concentrated on analyzing the style of eruption during orbit I27 (February 2000). Comparison with a lava flow cooling model indicates that the behavior of the Tvashtar eruption during I27 does not match that of "simple" advancing lava flows. Instead, it may be an active lava lake or a complex set of lava flows with episodic, overlapping (in time and space) eruptions.

  6. Heating of active region cores: Impulsive or steady?

    Tripathi, Durgesh

    The question of active region heating has proven to be highly challenging since its discovery in 1940s. The recent observational facilities have shed new lights towards the understanding of this problem. In this paper we review some of the new measurements to study the heating mechanisms in the hot core loops of active regions using the observations recorded by Solar Ultraviolet Measurements of Emitted Radiation (SUMER) onboard SoHO and the Extreme-ultraviolet Imaging Spectrometer (EIS) aboard Hinode. These new measurements show that the properties of hot core loops are consistent with by impulsive heating -- low frequency nanoflare - scenario. However, the evidences are not strong enough to rule-out steady heating completely. Further measurement using better spectral resolution and temperature coverage is required, which will be provided by Interface Region Imaging Spectrometer (IRIS) and Solar-C in near future.

  7. Active region upflows: 2. Data driven MHD modeling

    Galsgaard, K; Vanninathan, K; Huang, Z; Presmann, M

    2015-01-01

    Context. Observations of many active regions show a slow systematic outflow/upflow from their edges lasting from hours to days. At present no physical explanation has been proven, while several suggestions have been put forward. Aims. This paper investigates one possible method for maintaining these upflows assuming that convective motions drive the magnetic field to initiate them through magnetic reconnection. Methods. We use Helioseismic and Magnetic Imager (HMI) data to provide an initial potential three dimensional magnetic field of the active region NOAA 11123 on 2010 November 13 where the characteristic upflow velocities are observed. A simple one-dimensional hydrostatic atmospheric model covering the region from the photosphere to the corona is derived. Local Correlation Tracking of the magnetic features in the HMI data is used to derive a proxy for the time dependent velocity field. The time dependent evolution of the system is solved using a resistive three-dimensional MagnetoHydro-Dynamic code. Resu...

  8. Suzaku observations of 'bare' active galactic nuclei

    Walton, D J; Fabian, A C; Gallo, L C; Reis, R C

    2012-01-01

    We present a X-ray spectral analysis of a large sample of 25 'bare' active galactic nuclei, sources with little or no complicating intrinsic absorption, observed with Suzaku. Our work focuses on studying the potential contribution from relativistic disc reflection, and examining the implications of this interpretation for the intrinsic spectral complexities frequently displayed by AGN in the X-ray bandpass. During the analysis, we take the unique approach of attempting to simultaneously undertake a systematic analysis of the whole sample, as well as a detailed treatment of each individual source, and find that disc reflection has the required flexibility to successfully reproduce the broadband spectrum observed for all of the sources considered. Where possible, we use the reflected emission to place constraints on the black hole spin for this sample of sources. Our analysis suggests a general preference for rapidly rotating black holes, which if taken at face value is most consistent with the scenario in whic...

  9. Global estimation of burned area using MODIS active fire observations

    GIGLIO, L.; G. R. van der Werf; J. T. Randerson; Collatz, G. J.; Kasibhatla, P.

    2006-01-01

    We present a method for estimating monthly burned area globally at 1° spatial resolution using Terra MODIS data and ancillary vegetation cover information. Using regression trees constructed for 14 different global regions, MODIS active fire observations were calibrated to ''true'' burned area estimates derived from 500-m MODIS imagery based on the conventional assumption that burned area is proportional to counts of fire pixels. Unlike earlier methods, we...

  10. First observation of top quark production in the forward region.

    Aaij, R; Adeva, B; Adinolfi, M; Affolder, A; Ajaltouni, Z; Akar, S; Albrecht, J; Alessio, F; Alexander, M; Ali, S; Alkhazov, G; Alvarez Cartelle, P; Alves, A A; Amato, S; Amerio, S; Amhis, Y; An, L; Anderlini, L; Anderson, J; Andreotti, M; Andrews, J E; Appleby, R B; Aquines Gutierrez, O; Archilli, F; d'Argent, P; Artamonov, A; Artuso, M; Aslanides, E; Auriemma, G; Baalouch, M; Bachmann, S; Back, J J; Badalov, A; Baesso, C; Baldini, W; Barlow, R J; Barschel, C; Barsuk, S; Barter, W; Batozskaya, V; Battista, V; Bay, A; Beaucourt, L; Beddow, J; Bedeschi, F; Bediaga, I; Bel, L J; Belyaev, I; Ben-Haim, E; Bencivenni, G; Benson, S; Benton, J; Berezhnoy, A; Bernet, R; Bertolin, A; Bettler, M-O; van Beuzekom, M; Bien, A; Bifani, S; Bird, T; Birnkraut, A; Bizzeti, A; Blake, T; Blanc, F; Blouw, J; Blusk, S; Bocci, V; Bondar, A; Bondar, N; Bonivento, W; Borghi, S; Borsato, M; Bowcock, T J V; Bowen, E; Bozzi, C; Braun, S; Brett, D; Britsch, M; Britton, T; Brodzicka, J; Brook, N H; Bursche, A; Buytaert, J; Cadeddu, S; Calabrese, R; Calvi, M; Calvo Gomez, M; Campana, P; Campora Perez, D; Capriotti, L; Carbone, A; Carboni, G; Cardinale, R; Cardini, A; Carniti, P; Carson, L; Carvalho Akiba, K; Casse, G; Cassina, L; Castillo Garcia, L; Cattaneo, M; Cauet, Ch; Cavallero, G; Cenci, R; Charles, M; Charpentier, Ph; Chefdeville, M; Chen, S; Cheung, S-F; Chiapolini, N; Chrzaszcz, M; Cid Vidal, X; Ciezarek, G; Clarke, P E L; Clemencic, M; Cliff, H V; Closier, J; Coco, V; Cogan, J; Cogneras, E; Cogoni, V; Cojocariu, L; Collazuol, G; Collins, P; Comerma-Montells, A; Contu, A; Cook, A; Coombes, M; Coquereau, S; Corti, G; Corvo, M; Couturier, B; Cowan, G A; Craik, D C; Crocombe, A; Cruz Torres, M; Cunliffe, S; Currie, R; D'Ambrosio, C; Dalseno, J; David, P N Y; Davis, A; De Bruyn, K; De Capua, S; De Cian, M; De Miranda, J M; De Paula, L; De Silva, W; De Simone, P; Dean, C-T; Decamp, D; Deckenhoff, M; Del Buono, L; Déléage, N; Demmer, M; Derkach, D; Deschamps, O; Dettori, F; Di Canto, A; Di Ruscio, F; Dijkstra, H; Donleavy, S; Dordei, F; Dorigo, M; Dosil Suárez, A; Dossett, D; Dovbnya, A; Dreimanis, K; Dufour, L; Dujany, G; Dupertuis, F; Durante, P; Dzhelyadin, R; Dziurda, A; Dzyuba, A; Easo, S; Egede, U; Egorychev, V; Eidelman, S; Eisenhardt, S; Eitschberger, U; Ekelhof, R; Eklund, L; El Rifai, I; Elsasser, Ch; Ely, S; Esen, S; Evans, H M; Evans, T; Falabella, A; Färber, C; Farinelli, C; Farley, N; Farry, S; Fay, R; Ferguson, D; Fernandez Albor, V; Ferrari, F; Ferreira Rodrigues, F; Ferro-Luzzi, M; Filippov, S; Fiore, M; Fiorini, M; Firlej, M; Fitzpatrick, C; Fiutowski, T; Fohl, K; Fol, P; Fontana, M; Fontanelli, F; Forty, R; Francisco, O; Frank, M; Frei, C; Frosini, M; Fu, J; Furfaro, E; Gallas Torreira, A; Galli, D; Gallorini, S; Gambetta, S; Gandelman, M; Gandini, P; Gao, Y; García Pardiñas, J; Garofoli, J; Garra Tico, J; Garrido, L; Gascon, D; Gaspar, C; Gastaldi, U; Gauld, R; Gavardi, L; Gazzoni, G; Geraci, A; Gerick, D; Gersabeck, E; Gersabeck, M; Gershon, T; Ghez, Ph; Gianelle, A; Gianì, S; Gibson, V; Girard, O G; Giubega, L; Gligorov, V V; Göbel, C; Golubkov, D; Golutvin, A; Gomes, A; Gotti, C; Grabalosa Gándara, M; Graciani Diaz, R; Granado Cardoso, L A; Graugés, E; Graverini, E; Graziani, G; Grecu, A; Greening, E; Gregson, S; Griffith, P; Grillo, L; Grünberg, O; Gui, B; Gushchin, E; Guz, Yu; Gys, T; Hadavizadeh, T; Hadjivasiliou, C; Haefeli, G; Haen, C; Haines, S C; Hall, S; Hamilton, B; Hampson, T; Han, X; Hansmann-Menzemer, S; Harnew, N; Harnew, S T; Harrison, J; He, J; Head, T; Heijne, V; Hennessy, K; Henrard, P; Henry, L; Hernando Morata, J A; van Herwijnen, E; Heß, M; Hicheur, A; Hill, D; Hoballah, M; Hombach, C; Hulsbergen, W; Humair, T; Hussain, N; Hutchcroft, D; Hynds, D; Idzik, M; Ilten, P; Jacobsson, R; Jaeger, A; Jalocha, J; Jans, E; Jawahery, A; Jing, F; John, M; Johnson, D; Jones, C R; Joram, C; Jost, B; Jurik, N; Kandybei, S; Kanso, W; Karacson, M; Karbach, T M; Karodia, S; Kelsey, M; Kenyon, I R; Kenzie, M; Ketel, T; Khanji, B; Khurewathanakul, C; Klaver, S; Klimaszewski, K; Kochebina, O; Kolpin, M; Komarov, I; Koopman, R F; Koppenburg, P; Korolev, M; Kozeiha, M; Kravchuk, L; Kreplin, K; Kreps, M; Krocker, G; Krokovny, P; Kruse, F; Kucewicz, W; Kucharczyk, M; Kudryavtsev, V; Kuonen, A K; Kurek, K; Kvaratskheliya, T; La Thi, V N; Lacarrere, D; Lafferty, G; Lai, A; Lambert, D; Lambert, R W; Lanfranchi, G; Langenbruch, C; Langhans, B; Latham, T; Lazzeroni, C; Le Gac, R; van Leerdam, J; Lees, J-P; Lefèvre, R; Leflat, A; Lefrançois, J; Leroy, O; Lesiak, T; Leverington, B; Li, Y; Likhomanenko, T; Liles, M; Lindner, R; Linn, C; Lionetto, F; Liu, B; Liu, X; Loh, D; Lohn, S; Longstaff, I; Lopes, J H; Lucchesi, D; Lucio Martinez, M; Luo, H; Lupato, A; Luppi, E; Lupton, O; Machefert, F; Maciuc, F; Maev, O; Maguire, K; Malde, S; Malinin, A; Manca, G; Mancinelli, G; Manning, P; Mapelli, A; Maratas, J; Marchand, J F; Marconi, U; Marin Benito, C; Marino, P; Märki, R; Marks, J; Martellotti, G; Martin, M; Martinelli, M; Martinez Santos, D; Martinez Vidal, F; Martins Tostes, D; Massafferri, A; Matev, R; Mathad, A; Mathe, Z; Matteuzzi, C; Matthieu, K; Mauri, A; Maurin, B; Mazurov, A; McCann, M; McCarthy, J; McNab, A; McNulty, R; Meadows, B; Meier, F; Meissner, M; Melnychuk, D; Merk, M; Milanes, D A; Minard, M-N; Mitzel, D S; Molina Rodriguez, J; Monteil, S; Morandin, M; Morawski, P; Mordà, A; Morello, M J; Moron, J; Morris, A B; Mountain, R; Muheim, F; Müller, J; Müller, K; Müller, V; Mussini, M; Muster, B; Naik, P; Nakada, T; Nandakumar, R; Nandi, A; Nasteva, I; Needham, M; Neri, N; Neubert, S; Neufeld, N; Neuner, M; Nguyen, A D; Nguyen, T D; Nguyen-Mau, C; Niess, V; Niet, R; Nikitin, N; Nikodem, T; Ninci, D; Novoselov, A; O'Hanlon, D P; Oblakowska-Mucha, A; Obraztsov, V; Ogilvy, S; Okhrimenko, O; Oldeman, R; Onderwater, C J G; Osorio Rodrigues, B; Otalora Goicochea, J M; Otto, A; Owen, P; Oyanguren, A; Palano, A; Palombo, F; Palutan, M; Panman, J; Papanestis, A; Pappagallo, M; Pappalardo, L L; Pappenheimer, C; Parkes, C; Passaleva, G; Patel, G D; Patel, M; Patrignani, C; Pearce, A; Pellegrino, A; Penso, G; Pepe Altarelli, M; Perazzini, S; Perret, P; Pescatore, L; Petridis, K; Petrolini, A; Petruzzo, M; Picatoste Olloqui, E; Pietrzyk, B; Pilař, T; Pinci, D; Pistone, A; Piucci, A; Playfer, S; Plo Casasus, M; Poikela, T; Polci, F; Poluektov, A; Polyakov, I; Polycarpo, E; Popov, A; Popov, D; Popovici, B; Potterat, C; Price, E; Price, J D; Prisciandaro, J; Pritchard, A; Prouve, C; Pugatch, V; Puig Navarro, A; Punzi, G; Qian, W; Quagliani, R; Rachwal, B; Rademacker, J H; Rakotomiaramanana, B; Rama, M; Rangel, M S; Raniuk, I; Rauschmayr, N; Raven, G; Redi, F; Reichert, S; Reid, M M; Dos Reis, A C; Ricciardi, S; Richards, S; Rihl, M; Rinnert, K; Rives Molina, V; Robbe, P; Rodrigues, A B; Rodrigues, E; Rodriguez Lopez, J A; Rodriguez Perez, P; Roiser, S; Romanovsky, V; Romero Vidal, A; Ronayne, J W; Rotondo, M; Rouvinet, J; Ruf, T; Ruiz, H; Ruiz Valls, P; Saborido Silva, J J; Sagidova, N; Sail, P; Saitta, B; Salustino Guimaraes, V; Sanchez Mayordomo, C; 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Yu, J; Yuan, X; Yushchenko, O; Zangoli, M; Zavertyaev, M; Zhang, L; Zhang, Y; Zhelezov, A; Zhokhov, A; Zhong, L

    2015-09-11

    Top quark production in the forward region in proton-proton collisions is observed for the first time. The W+b final state with W→μν is reconstructed using muons with a transverse momentum, p_{T}, larger than 25 GeV in the pseudorapidity range 2.020  GeV. The results are based on data corresponding to integrated luminosities of 1.0 and 2.0  fb^{-1} collected at center-of-mass energies of 7 and 8 TeV by LHCb. The inclusive top quark production cross sections in the fiducial region are σ(top)[7  TeV]=239±53(stat)±33(syst)±24(theory)  fb,σ(top)[8  TeV]=289±43(stat)±40(syst)±29(theory)  fb.These results, along with the observed differential yields and charge asymmetries, are in agreement with next-to-leading order standard model predictions. PMID:26406821

  11. Solar Activity Studies using Microwave Imaging Observations

    Gopalswamy, N.

    2016-01-01

    We report on the status of solar cycle 24 based on polar prominence eruptions (PEs) and microwave brightness enhancement (MBE) information obtained by the Nobeyama radioheliograph. The north polar region of the Sun had near-zero field strength for more than three years (2012-2015) and ended only in September 2015 as indicated by the presence of polar PEs and the lack of MBE. The zero-polar-field condition in the south started only around 2013, but it ended by June 2014. Thus the asymmetry in the times of polarity reversal switched between cycle 23 and 24. The polar MBE is a good proxy for the polar magnetic field strength as indicated by the high degree of correlation between the two. The cross-correlation between the high- and low-latitude MBEs is significant for a lag of approximately 5.5 to 7.3 years, suggesting that the polar field of one cycle indicates the sunspot number of the next cycle in agreement with the Babcock-Leighton mechanism of solar cycles. The extended period of near-zero field in the north-polar region should result in a weak and delayed sunspot activity in the northern hemisphere in cycle 25.

  12. Atmosphere dynamics of the active region NOAA 11024

    Kondrashova, N N; Chornogor, S N; Khomenko, E V; 10.1007/s11207-012-0212-5

    2012-01-01

    We present results of the study of chromospheric and photospheric line-of-sight velocity fields in the young active region NOAA 11024. Multi-layer, multi-wavelength observational data were used for the analysis of the emerging flux in this active region. Spectropolarimetric observations were carried out with the telescope THEMIS on Tenerife (Canary Islands) on 4 July 2009. In addition, space-borne data from SOHO/MDI, STEREO and GOES were also considered. The combination of data from ground- and space-based telescopes allowed us to study the dynamics of the lower atmosphere of the active region with high spatial, spectral, and temporal resolutions. THEMIS spectra show strong temporal variations of the velocity in the chromosphere and photosphere for different activity features: two pores, active and quiet plage regions, and two surges. The range of variations of the chromospheric line-of-sight velocity at the heights of formation of the H-alpha core was extremely large. Both upward and downward motions were ob...

  13. Active region filaments might harbor weak magnetic fields

    Baso, C J Díaz; Ramos, A Asensio

    2016-01-01

    Recent spectropolarimetric observations of active region filaments have revealed polarization profiles with signatures typical of the strong field Zeeman regime. The conspicuous absence in those observations of scattering polarization and Hanle effect signatures was then pointed out by some authors. This was interpreted either as a signature of mixed "turbulent" field components or as a result of optical thickness. In this article, we present a natural scenario to explain these Zeeman-only spectro-polarimetric observations of active region filaments. We propose a two-component model, one on top of the other. Both components have horizontal fields, the azimuth difference between them being close to 90 degrees. The component that lies lower in the atmosphere is permeated by a strong field of the order of 600 G, while the upper component has much weaker fields, of the order of 10 G. The ensuing scattering polarization signatures of the individual components have opposite signs, so that its combination along the ...

  14. MESSENGER Observations of Substorm Activity at Mercury

    Sun, W. J.; Slavin, J. A.; Fu, S.; Raines, J. M.; Zong, Q. G.; Poh, G.; Jia, X.; Sundberg, T.; Gershman, D. J.; Pu, Z.; Zurbuchen, T.; Shi, Q.

    2015-12-01

    MErcury Surface, Space ENviroment, GEochemistry, and Ranging (MESSENGER) magnetic field and plasma measurements taken during crossings of Mercury's magnetotail from 2011 to 2014 have been investigated for substorms. A number of events with clear Earth-like growth phase and expansion phase signatures were found. The thinning of the plasma sheet and the increase of magnetic field intensity in the lobe were observed during the growth phase and plasma sheet was observed to thicken during the expansion phase, which are similar to the observations at Earth. But the time scale of Mercury's substorm is only several minutes comparing with the several hours at Earth [Sun et al., 2015a]. Detailed analysis of magnetic field fluctuations during the substorm expansion phase have revealed low frequency plasma waves, e.g. Pi2-like pulsations. The By fluctuations accompanying substorm dipolarizations are consistent with pulses of field-aligned currents near the high latitude edge of the plasma sheet. Further study shows that they are near-circularly polarized electromagnetic waves, most likely Alfvén waves. Soon afterwards the plasma sheet thickened and MESSENGER detected a series of compressional waves. We have also discussed their possible sources [Sun et al., 2015b]. Sun, W.-J., J. A. Slavin, S. Y. Fu, et al. (2015a), MESSENGER observations of magnetospheric substorm activity in Mercury's near magnetotail. Geophys. Res. Lett., 42, 3692-3699. doi: 10.1002/2015GL064052.Sun, W.-J., J. A. Slavin, S. Y. Fu, et al. (2015b), MESSENGER observations of Alfvénic and compressional waves during Mercury's substorms. Geophys. Res. Lett., 42, in press. doi: 10.1002/ 2015GL065452.

  15. Photochemistry of an Urban Region using Observations and Numerical Modeling

    Cantrell, C. A.; Mauldin, L.; Mukherjee, A. D.; Flocke, F. M.; Pfister, G.; Apel, E. C.; Bahreini, R.; Blake, D. R.; Blake, N. J.; Campos, T. L.; Cohen, R. C.; Farmer, D.; Fried, A.; Guenther, A. B.; Hall, S. R.; Heikes, B.; Hornbrook, R. S.; Huey, L. G.; Karl, T.; Kaser, L.; Nowak, J. B.; Ortega, J. V.; O'Sullivan, D. W.; Richter, D.; Smith, J. N.; Tanner, D.; Townsend-Small, A.; Ullmann, K.; Walega, J.; Weibring, P.; Weinheimer, A. J.

    2015-12-01

    The chemistry of HOx radicals in the troposphere can lead to the production of secondary products such as ozone and aerosols, while volatile organic compounds are degraded. The production rates and identities of secondary products depend on the abundance of NOx and other parameters. The amounts of VOCs and NOx can also affect the concentrations of OH, HO2 and RO2. Comparison of observations and model-derived values of HOx species can provide one way to assess the completeness and accuracy of model mechanisms. The functional dependence of measure-model agreement on various controlling parameters can also reveal details of current understanding of photochemistry in urban regions. During the Front Range Air Pollution and Photochemistry Experiment (FRAPPE), conducted during the summer of 2014, observations from ground-based and airborne platforms were performed to study the evolution of atmospheric composition over the Denver metropolitan area. Of particular interest in FRAPPE was the assessment of the roles of mixing of emissions from oil and gas exploration and extraction, and those from confined animal production operations, with urban emissions (e.g. from transportation, energy production, and industrial processes) on air quality in the metropolitan and surrounding region. Our group made measurements of OH, HO2, and HO2 + RO2 from the NSF/NCAR C-130 aircraft platform using selected ion chemical ionization mass spectrometry. The C-130 was equipped with instrumentation for the observation of a wide variety of photochemical-related species and parameters. These data are used to assess the photochemical regimes encountered during the period of the study, and to quantitatively describe the chemical processes involved in formation of secondary products. One of the tools used is a steady state model for short-lived species such as those that we observed. This presentation summarizes the behavior of species that were measured during FRAPPE and what the observations reveal

  16. Eruptions that Drive Coronal Jets in a Solar Active Region

    Sterling, Alphonse C.; Moore, Ronald L.; Falconer, David A.; Panesar, Navdeep K.; Akiyama, Sachiko; Yashiro, Seiji; Gopalswamy, Nat

    2016-01-01

    Solar coronal jets are common in both coronal holes and in active regions (e.g., Shibata et al. 1992, Shimojo et al. 1996, Cirtain et al. 2007. Savcheva et al. 2007). Recently, Sterling et al. (2015), using data from Hinode/XRT and SDO/AIA, found that coronal jets originating in polar coronal holes result from the eruption of small-scale filaments (minifilaments). The jet bright point (JBP) seen in X-rays and hotter EUV channels off to one side of the base of the jet's spire develops at the location where the minifilament erupts, consistent with the JBPs being miniature versions of typical solar flares that occur in the wake of large-scale filament eruptions. Here we consider whether active region coronal jets also result from the same minifilament-eruption mechanism, or whether they instead result from a different mechanism (e.g. Yokoyama & Shibata 1995). We present observations of an on-disk active region (NOAA AR 11513) that produced numerous jets on 2012 June 30, using data from SDO/AIA and HMI, and from GOES/SXI. We find that several of these active region jets also originate with eruptions of miniature filaments (size scale 20'') emanating from small-scale magnetic neutral lines of the region. This demonstrates that active region coronal jets are indeed frequently driven by minifilament eruptions. Other jets from the active region were also consistent with their drivers being minifilament eruptions, but we could not confirm this because the onsets of those jets were hidden from our view. This work was supported by funding from NASA/LWS, NASA/HGI, and Hinode. A full report of this study appears in Sterling et al. (2016).

  17. Observed regional distribution of sulfur dioxide in Asia

    Increased use of coal for energy in Asia has led to increased SO2 emissions. SO2 concentrations have been measured for one year at forty-five locations throughout Asia using passive samplers. Duplicate samples were exposed at each site for one month intervals. The sites were selected to provide background information on the distribution of SO2 over wide geographical regions, with emphasis on the regional characteristics around areas estimated to be sensitive to sulfur deposition. The annual mean values ranged from less than 0.3 μg/m3 at Tana Rata, located at 1545 m on the Malaysia Peninsula, Lawa Mandau (Borneo), Malaysia, and Dhankuta, Nepal, to values greater than 20 μg/m3 at Luchongguan (Guiyang) China, Babar Mahal, Nepal, and Hanoi, Vietnam. In general high concentrations were measured throughout China, with the highest concentrations in the heavy industrial areas in Guiyang. The concentrations in east Asia around the Korea peninsula were ∼ 5 μg/m3. The concentrations in the southeast Asia tropics were low, with no station in Malaysia and Indonesia having average concentrations exceeding 1.7 μg/m3. The observed SO2 concentrations were found to display a distinct seasonal cycle which is strongly influenced by the seasonality of winds and precipitation patterns. 3 refs., 3 figs

  18. Ambient air quality observations in the Athabasca oil sands region

    Both Syncrude and Suncor have plans to develop new oil sands leases and to increase crude oil and bitumen recovery in the Athabasca oil sands region. In recognition of the effects that this will have on the environment, Suncor has proposed modifications to reduce SO2 emissions to the atmosphere, while Syncrude plans to develop additional ambient air quality, sulphur deposition and biomonitoring programs. This report discussed the ambient air quality monitoring that was undertaken in the Fort McMurray-Fort McKay airshed. Twelve continuous ambient air quality stations and 76 passive monitoring stations are maintained in the region. Environment Canada maintains eight precipitation monitoring stations in northern Alberta and Saskatchewan. Source characterization, ambient air quality and meteorology observations, air quality monitoring, and air quality data from continuous sulphur dioxide, hydrogen sulphide, nitrogen oxides, ozone, carbon monoxide, hydrocarbon, acid rain and particulates analyzers were reviewed. The documentation of all computer files used for the analysis of the air quality data is discussed in the Appendix. 47 refs., 39 tabs., 53 figs

  19. Regional circulation around New Caledonia from two decades of observations

    Cravatte, Sophie; Kestenare, Elodie; Eldin, Gérard; Ganachaud, Alexandre; Lefèvre, Jérôme; Marin, Frédéric; Menkes, Christophe; Aucan, Jérôme

    2015-08-01

    The regional and near-coastal circulation around New Caledonia is investigated using a compilation of more than 20 years of observations. Velocity profiles acquired by Shipboard Acoustic Doppler Current Profiler (SADCP) during 109 research cruises and ship transits since 1991 are analyzed and compared with absolute geostrophic currents inferred from hydrographic profiles and Argo floats drifts. In addition, altimetric surface currents are used to explore the variability of the circulation at various timescales. By making the best use of the strength of these various observations, this study provides an unprecedented detailed picture of the mean circulation around New Caledonia and of its variability in the upper layers. New Caledonia, together with the Vanuatu Archipelago and the Fiji Islands, acts as a 750-km long obstacle to the westward South Equatorial Current (SEC) entering the Coral Sea. On average, the SEC bifurcates against New Caledonia's east coast into a northwestward boundary current, the East Caledonian Current, beginning east of the Loyalty Islands and extending to at least 1000 m depth, and into a weak southeastward current. The latter, the Vauban Current, flows into the Loyalty channel against the mean trade winds where it extends to at least 500 m depth. It is highly variable at intraseasonal timescales; it often reverses and its variability is mainly driven by incoming mesoscale eddies east and south of New Caledonia. West of the Island, the southeastward Alis Current of New Caledonia (ACNC) flows along the reef slope in the 0-150 m layer. It overlays a weaker northwestward current, creating an unusual coastal circulation reminiscent of the current system along the Australian west coast. The ACNC is a persistent feature of the observations, even if its transport is also strongly modulated by the presence of offshore eddies. This study highlights the fact, if needed, that a snapshot view of the currents provided by a single transect can be strongly

  20. Observation of low frequency electromagnetic activity at 1000 km altitude

    N. Ivchenko

    Full Text Available We present a statistical study of low frequency fluctuations of electric and magnetic fields, commonly interpreted as Alfvénic activity. The data base consists of six months of electric and magnetic field measurements by the Astrid-2 microsatellite. The occurrence of the events is studied with respect to the location and general activity. Large regions of broadband Alfvénic activity are persistently observed in the cusp/cleft and, during the periods of high geo-magnetic activity, also in the pre-midnight sector of the auroral oval.

    Key words. Ionosphere (auroral ionosphere – Space plasma physics (waves and instabilities – Magnetospheric physics (magnetosphere-ionosphere interactions

  1. Time Dependent Non-Equilibrium Ionization of Transition Region Lines Observed with IRIS

    Martinez-Sykora, Juan; Hansteen, Viggo H; Gudiksen, Boris V

    2015-01-01

    The properties of non-statistical equilibrium ionization of silicon and oxygen ions are analyzed in this work. We focus on four solar targets (quiet sun, coronal hole, plage, quiescent active region, AR, and flaring AR) as observed with the Interface Region Imaging Spectrograph (IRIS). IRIS is best suited for this work due to the high cadence (up to 0.5s), high spatial resolution (up to 0.32"), and high signal to noise ratios for O IV and Si IV. We find that the observed intensity ratio between lines of three times ionized silicon and oxygen ions depends on their total intensity and that this correlation varies depending on the region observed (quiet sun, coronal holes, plage or active regions) and on the specific observational objects present (spicules, dynamic loops, jets, micro-flares or umbra). In order to interpret the observations, we compare them with synthetic profiles taken from 2D self-consistent radiative MHD simulations of the solar atmosphere, where the statistical equilibrium or non-equilibrium ...

  2. DOPPLER SHIFTS IN ACTIVE REGION MOSS USING SOHO/SUMER

    Winebarger, Amy [NASA Marshall Space Flight Center, VP 62, Huntsville, AL 35812 (United States); Tripathi, Durgesh [Inter-University Centre for Astronomy and Astrophysics, Post Bag 4, Ganeshkhind, Pune 411 007 (India); Mason, Helen E.; Del Zanna, Giulio [Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA (United Kingdom)

    2013-04-20

    The velocity of the plasma at the footpoint of hot loops in active region cores can be used to discriminate between different heating frequencies. Velocities on the order of a few kilometers per second would indicate low-frequency heating on sub-resolution strands, while velocities close to zero would indicate high-frequency (steady) heating. To discriminate between these two values requires accurate velocity measurements; previous velocity measurements suffer from large uncertainties, mainly due to the lack of an absolute wavelength reference scale. In this paper, we determine the velocity in the loop footpoints using observations from Solar Ultraviolet Measurements of Emitted Radiation (SUMER) on Solar and Heliospheric Observatory. We use neutral spectral lines to determine the wavelength scale of the observations with an uncertainty in the absolute velocity of <3.5 km s{sup -1} and co-aligned Transition Region and Coronal Explorer (TRACE) images to identify footpoint regions. We studied three different active regions and found average redshifts in the Ne VIII 770 A emission line (formed at 6 Multiplication-Sign 10{sup 5} K) of 5.17 {+-} 5.37 km s{sup -1} and average redshifts in the C IV 1548 and 1550 A emission lines (formed at 1 Multiplication-Sign 10{sup 5} K) of 13.94 {+-} 4.93 km s{sup -1} and 14.91 {+-} 6.09 km s{sup -1}, respectively. We find no correlation between the brightness in the spectral line and the measured velocity, nor do we find correlation between the Ne VIII and C IV velocities measured co-spatially and co-temporally. SUMER scanned two of the active regions twice; in those active regions we find positive correlation between the co-spatial velocities measured during the first and second scans. These results provide definitive and quantitative measurements for comparisons with simulations of different coronal heating mechanisms.

  3. Size-Flux Relation in Solar Active Regions

    2003-01-01

    We present a study of the relationship between integral area and corre-sponding total magnetic flux for solar active regions. It is shown that some of theserelationships are satisfied to simple power laws. Fractal examination showed thatsome of these power laws can not be justified inside the simple models of stationarymagnetic flux tube aggregation. All magnetic fluxes and corresponding areas werecalculated using the data measured with the Solar Magnetic Field Telescope of theHuairou Solar Observing Station in Beijing.

  4. Active region upflows: 2. Data driven MHD modeling

    Galsgaard, K.; Madjarska, M. S.; Vanninathan, K.; Huang, Z; Presmann, M.

    2015-01-01

    Context. Observations of many active regions show a slow systematic outflow/upflow from their edges lasting from hours to days. At present no physical explanation has been proven, while several suggestions have been put forward. Aims. This paper investigates one possible method for maintaining these upflows assuming that convective motions drive the magnetic field to initiate them through magnetic reconnection. Methods. We use Helioseismic and Magnetic Imager (HMI) data to provide an initial ...

  5. On the Magnetic Field Strength of Active Region Filaments

    Kuckein, C; Pillet, V Martinez; Casini, R; Sainz, R Manso; Shimizu, T

    2009-01-01

    We study the vector magnetic field of a filament observed over a compact Active Region Neutral Line. Spectropolarimetric data acquired with TIP-II (VTT, Tenerife, Spain) of the 10830 \\AA spectral region provide full Stokes vectors which were analyzed using three different methods: magnetograph analysis, Milne-Eddington inversions and PCA-based atomic polarization inversions. The inferred magnetic field strengths in the filament are of the order of 600 - 700 G by all these three methods. Longitudinal fields are found in the range of 100 - 200 G whereas the transverse components become dominant, with fields as large as 500 - 600 G. We find strong transverse fields near the Neutral Line also at photospheric levels. Our analysis indicates that strong (higher than 500 G, but below kG) transverse magnetic fields are present in Active Region filaments. This corresponds to the highest field strengths reliably measured in these structures. The profiles of the Helium 10830 \\AA lines observed in this Active Region filam...

  6. Observing the reconnection region in a transequatorial loop system

    Liu, Rui; Wang, Tong-Jiang; Lee, Jeongwoo; Stenborg, Guillermo; Liu, Chang; Park, Sung-Hong; Wang, Hai-Min

    2011-10-01

    A vertical current sheet is a crucial element in many flare/coronal mass ejection (CME) models. For the first time, Liu et al. reported a vertical current sheet directly imaged during the flare rising phase with the EUV Imaging Telescope (EIT) onboard the Solar and Heliospheric Observatory (SOHO). As a follow-up study, here we present the comprehensive analysis and detailed physical interpretation of the observation. The current sheet formed due to the gradual rise of a transequatorial loop system. As the loop legs approached each other, plasma flew at ~ 6 km s-1 into a local area where a cusp-shaped flare loop subsequently formed and the current sheet was seen as a bright, collimated structure of global length (>= 0.25 Rodot) and macroscopic width ((5-10)×103km), extending from 50 Mm above the flaring loop to the border of the EIT field of view (FOV). The reconnection rate in terms of the Alfvén Mach number is estimated to be only 0.005-0.009, albeit a halo CME was accelerated from ~ 400 km s-1 to ~ 1300 km s-1 within the coronagraph FOV. Drifting pulsating structures at metric frequencies were recorded during the impulsive phase, implying tearing of the current sheet in the high corona. A radio Type III burst occurred when the current sheet was clearly seen in EUV, indicative of accelerated electrons beaming upward from the upper tip of the current sheet. A cusp-shaped dimming region was observed to be located above the post-flare arcade during the decay phase in EIT; both the arcade and the dimming expanded with time. With the Coronal Diagnostic Spectrometer (CDS) aboard SOHO, a clear signature of chromospheric evaporation was seen during the decay phase, i.e., the cusp-shaped dimming region was associated with plasma upflows detected with EUV hot emission lines, while the post-flare loop was associated with downflows detected with cold lines. This event provides a comprehensive view of the reconnection geometry and dynamics in the solar corona.

  7. Observing the reconnection region in a transequatorial loop system

    Rui Liu; Tong-Jiang Wang; Jeongwoo Lee; Guillermo Stenborg; Chang Liu; Sung-Hong Park; Hai-Min Wang

    2011-01-01

    A vertical current sheet is a crucial element in many flare/coronal mass ejection (CME) models.For the first time,Liu et al.reported a vertical current sheet directly imaged during the flare rising phase with the EUV Imaging Telescope (EIT) onboard the Solar and Heliospheric Observatory (SOHO).As a follow-up study,here we present the comprehensive analysis and detailed physical interpretation of the observation.The current sheet formed due to the gradual rise of a transequatorial loop system.As the loop legs approached each other,plasma flew at ~6 km s-1 into a local area where a cusp-shaped flare loop subsequently formed and the current sheet was seen as a bright,collimated structure of global length (≥ 0.25 R(@)) and macroscopic width ((5-10)× 103 km),extending from 50 Mm above the flaring loop to the border of the EIT field of view (FOV).The reconnection rate in terms of the Alfvén Mach number is estimated to be only 0.005-0.009,albeit a halo CME was accelerated from ~ 400 km s- 1 to ~ 1300 km s- 1 within the coronagraph FOV.Drifting pulsating structures at metric frequencies were recorded during the impulsive phase,implying tearing of the current sheet in the high corona.A radio Type Ⅲ burst occurred when the current sheet was clearly seen in EUV,indicative of accelerated electrons beaming upward from the upper tip of the current sheet.A cusp-shaped dimming region was observed to be located above the post-flare arcade during the decay phase in EIT;both the arcade and the dimming expanded with time.With the Coronal Diagnostic Spectrometer (CDS) aboard SOHO,a clear signature of chromospheric evaporation was seen during the decay phase,i.e.,the cusp-shaped dimming region was associated with plasma upflows detected with EUV hot emission lines,while the post-flare loop was associated with downflows detected with cold lines.This event provides a comprehensive view of the reconnection geometry and dynamics in the solar corona.

  8. Higher Education in Balkan Region and its Contribution to the Earth Observation

    Lisec, A.; Fras, M. K.

    2012-07-01

    The needs for spatial data as well as techniques of Earth Observation are changing, and new professional areas are developing very rapidly. In addition, scientific work and its connection with the teaching process have influenced the introduction of new cognitions into the higher education programs in general. Considering these facts, in the period shorter than one decade, the higher education institutions in the Balkan region, which have study programs in the fields of spatial data acquisition, analysis and spatial decisions, have made significant changes of the curricula. In our research, we have analyzed the current higher education programs in the Balkan region having focused on curricula related to the Earth Observation. Due to historical reasons, these curricula have its roots in surveying study programs in the most Balkan countries. The competences of classical surveying higher educational programs have been changing and nowadays include the wider area of spatial data acquisition, geoinformatics. In parallel, we present the current Earth Observation activities in the selected countries from the Balkan region. Based on the results of our research in the framework of the European program Observe, which aims to establish a new Balkan Earth Observation (EO) community of multilevel stakeholders that will make use of state of the art technological developments, products and knowhow from the existing European EO community and industry, we estimate the contribution of advanced higher educational programs to the Earth Observation activities in the selected countries.

  9. Light walls around sunspots observed by the Interface Region Imaging Spectrograph

    Hou, Y. J.; Li, T.; Yang, S. H.; Zhang, J.

    2016-04-01

    Context. The Interface Region Imaging Spectrograph (IRIS) mission provides high-resolution observations of the chromosphere and transition region. Using these data, some authors have reported the new finding of light walls above sunspot light bridges. Aims: We try to determine whether the light walls exist somewhere else in active regions in addition to the light bridges. We also examine how the material of these walls evolves. Methods: Employing six months of (from 2014 December to 2015 June) high tempo-spatial data from the IRIS, we find many light walls either around sunspots or above light bridges. Results: For the first time, we report one light wall near an umbral-penumbral boundary and another along a neutral line between two small sunspots. The former light wall has a multilayer structure and is associated with the emergence of positive magnetic flux in the ambient negative field. The latter light wall is associated with a filament activation, and the wall body consists of the filament material, which flowed to a remote plage region with a negative magnetic field after the light wall disappeared. Conclusions: These new observations reveal that these light walls are multilayer and multithermal structures that occur along magnetic neutral lines in active regions. Movies associated to Figs. 1-4 are available in electronic form at http://www.aanda.org

  10. Dynamic Precursors of Flares in Active Region NOAA 10486

    M. B. Korsós; N. Gyenge; T. Baranyi; A. Ludmány

    2015-03-01

    Four different methods are applied here to study the precursors of flare activity in the Active Region NOAA 10486. Two approaches track the temporal behaviour of suitably chosen features (one, the weighted horizontal gradient WGM, is the generalized form of the horizontal gradient of the magnetic field, GM; the other is the sum of the horizontal gradient of the magnetic field, GS, for all sunspot pairs). WGM is a photospheric indicator, that is a proxy measure of magnetic non-potentiality of a specific area of the active region, i.e., it captures the temporal variation of the weighted horizontal gradient of magnetic flux summed up for the region where opposite magnetic polarities are highly mixed. The third one, referred to as the separateness parameter, Sl−f, considers the overall morphology. Further, GS and Sl−f are photospheric, newly defined quick-look indicators of the polarity mix of the entire active region. The fourth method is tracking the temporal variation of small X-ray flares, their times of succession and their energies observed by the Reuven Ramaty High Energy Solar Spectroscopic Imager instrument. All approaches yield specific pre-cursory signatures for the imminence of flares.

  11. Regional Observations of the 2006 and 2009 Declared North Korea Nuclear Explosions

    Walter, W. R.; Ford, S. R.; Pasyanos, M. E.

    2009-12-01

    The October 2006 and May 2009 declared North Korean nuclear tests produced regional seismic phases, Pn, Pg, Sn and Lg that were observed at publically available seismic stations such as MDJ and TJN. In comparison with nearby earthquakes, the relatively low amplitudes of the S-wave phases at high frequencies can be used to identify these events as explosion-like, particularly when contrasted with P-waves, as in P/S ratios. However regional phase amplitudes can vary greatly over small distances, particularly as the crust and lithosphere thicknesses and velocity structures change due to tectonic activity. These variations can complicate simple methods to use P/S ratios to discriminate explosions from earthquakes over broad regions, particularly when there are not nearby events for comparison. In addition, when S-waves do not propagate effectively due to strong attenuation or structural variability, all events below a certain magnitude threshold from a source region to a station may have S-wave amplitudes below the P-wave coda level, leading to the large P/S amplitude ratios characteristic of explosions. Here we make use of earthquake spectral source models, and regional propagation models to compare events over the broad region around the Korean Peninsula. In particular we investigate the ability of the multi-phase regional attenuation tomography technique of Pasyanos et al. (2009) to reduce the geographic variability of earthquake P/S values in this region and enhance the ability to identify explosions by their regional phase characteristics.

  12. Multi-point observations of intermittency in the cusp regions

    M. M. Echim

    2007-08-01

    Full Text Available In this paper we investigate the statistical properties of magnetic field fluctuations measured by the four Cluster spacecraft in the cusp and close to the interface with the magnetospheric lobes, magnetopause and magnetosheath. At lower altitudes along the outbound orbit of 26 February 2001, the magnetic field fluctuations recorded by all four spacecraft are random and their Probability Distribution Functions (PDFs are Gaussian at all scales. The flatness parameter, F – related to the kurtosis of the time series, is equal to 3. At higher altitudes, in the cusp and its vicinity, closer to the interface with the magnetopause and magnetosheath, the PDFs from all Cluster satellites are non-Gaussian and show a clear intermittent behavior at scales smaller than τG≈ 61 s (or 170 km. The flatness parameter increases to values greater than 3 for scales smaller than τG. A Haar wavelet transform enables the identification of the "events" that produce sudden variations of the magnetic field and of the scales that have most of the power. The LIM parameter (i.e. normalized wavelet power indicates that events for scales below 65 s are non-uniformly distributed throughout the cusp passage. PDFs, flatness and wavelet analysis show that at coarse-grained scales larger than τG the intermittency is absent in the cusp. Fluctuations of the magnetic energy observed during the same orbit in the magnetosheath show PDFs that tend toward a Gaussian at scales smaller than τG found in the cusp. The flatness analysis confirms the decreasing of τG from cusp to magnetosheath. Our analysis reveals the turbulent cusp as a transition region from a non-intermittent turbulent state inside the magnetosphere to an intermittent turbulent state in the magnetosheath that has statistical properties resembling the solar wind turbulence. The observed turbulent fluctuations in the cusp suggests a phenomenon of nonlinear

  13. MESSENGER Observations of ULF Waves in Mercury's Foreshock Region

    Le, Guan; Chi, Peter J.; Bardsen, Scott; Blanco-Cano, Xochitl; Slavin, James A.; Korth, Haje

    2012-01-01

    The region upstream from a planetary bow shock is a natural plasma laboratory containing a variety of wave particle phenomena. The study of foreshocks other than the Earth s is important for extending our understanding of collisionless shocks and foreshock physics since the bow shock strength varies with heliocentric distance from the Sun, and the sizes of the bow shocks are different at different planets. The Mercury s bow shock is unique in our solar system as it is produced by low Mach number solar wind blowing over a small magnetized body with a predominately radial interplanetary magnetic field. Previous observations of Mercury upstream ultra-low frequency (ULF) waves came exclusively from two Mercury flybys of Mariner 10. The MESSENGER orbiter data enable us to study of upstream waves in the Mercury s foreshock in depth. This paper reports an overview of upstream ULF waves in the Mercury s foreshock using high-time resolution magnetic field data, 20 samples per second, from the MESSENGER spacecraft. The most common foreshock waves have frequencies near 2 Hz, with properties similar to the 1-Hz waves in the Earth s foreshock. They are present in both the flyby data and in every orbit of the orbital data we have surveyed. The most common wave phenomenon in the Earth s foreshock is the large-amplitude 30-s waves, but similar waves at Mercury have frequencies at 0.1 Hz and occur only sporadically with short durations (a few wave cycles). Superposed on the "30-s" waves, there are spectral peaks at 0.6 Hz, not reported previously in Mariner 10 data. We will discuss wave properties and their occurrence characteristics in this paper.

  14. Testing the regionalization of a SVAT model for a region with high observation density

    Eiermann, Sven; Thies, Boris; Bendix, Jörg

    2014-05-01

    The variable soil moisture is an important quantity in weather and climate investigations, because it has an essential influence on the energy exchange between the land surface and the atmosphere. However the recording of soil moisture in high spatio-temporal resolution is problematic. The planned Tandem-L mission of the German Aerospace Center (DLR) with an innovative L-band radar on board provides the opportunity to get daily soil moisture data at a spatial resolution of 50 meters. Within the Helmholtz Alliance Remote Sensing and Earth System Dynamics this data is planned to be used to regionalize a Soil Vegetation Atmosphere Transfer Model, in order to analyze the energy flux and the gas exchange and to improve the prediction of the water exchange between soil, vegetation and atmosphere. As investigation areas selected regions of the TERENO (TERrestrial ENviromental Observatoria) test sites and, later on, a region in South Ecuador will be used, for which data for the model initialization and validation are available. The reason for testing the method for the TERENO test sites first is the good data basis as a result of the already established high observation density there. The poster will present the methods being used for the model adaptation for the TERENO test sites and discuss the improvements achieved by these methods.

  15. Doppler Shifts in Active Region Moss Using SOHO/SUMER

    Winebarger, Amy; Tripathi, Durgesh; Mason, Helen E.; Del Zanna, Giulio

    2013-04-01

    The velocity of the plasma at the footpoint of hot loops in active region cores can be used to discriminate between different heating frequencies. Velocities on the order of a few kilometers per second would indicate low-frequency heating on sub-resolution strands, while velocities close to zero would indicate high-frequency (steady) heating. To discriminate between these two values requires accurate velocity measurements; previous velocity measurements suffer from large uncertainties, mainly due to the lack of an absolute wavelength reference scale. In this paper, we determine the velocity in the loop footpoints using observations from Solar Ultraviolet Measurements of Emitted Radiation (SUMER) on Solar and Heliospheric Observatory. We use neutral spectral lines to determine the wavelength scale of the observations with an uncertainty in the absolute velocity of SUMER scanned two of the active regions twice; in those active regions we find positive correlation between the co-spatial velocities measured during the first and second scans. These results provide definitive and quantitative measurements for comparisons with simulations of different coronal heating mechanisms.

  16. Project to Interface Climate Modeling on Global and Regional Scales with Earth Observing (EOS) Observations

    Dickinson, Robert E.

    2002-01-01

    This ten-year NASA IDS project began in 1990. Its initial work plan adopted the NASA provided timeline that data would become available for new Earth Observing System (EOS) platforms beginning in 1995. Over its first phase, it was based at NCAR, which had submitted the original proposal and involved activities of a substantial number of co-investigators at NCAR who engaged in research over several areas related to the observations expected to be received from the EOS platforms. Their focus was the theme of use of EOS data for improving climate models for projecting global change. From the climate system viewpoint, the IDS addressed land, clouds-hydrological cycle, radiative fluxes and especially aerosol impacts, ocean and sea-ice, and stratosphere. Other research addressed issues of data assimilation, diagnostic analyses, and data set development from current satellite systems, especially use of SAR data for climate models.

  17. Regional nitrogen oxides emission trends in East Asia observed from space

    B. Mijling

    2013-07-01

    Full Text Available Due to changing economic activity, emissions of air pollutants in East Asia change rapidly in space and time. Monthly emission estimates of nitrogen oxides derived from satellite observations provide valuable insight in the evolution of anthropogenic activity on a regional scale. We present the first results of a new emission estimation algorithm, specifically designed to use daily satellite observations of column concentrations for fast updates of emissions of short-lived atmospheric constituents on a~mesoscopic scale (~ 0.25° × 0.25°. The algorithm is used to construct a monthly NOx emission time series for 2007–2011 from tropospheric NO2 observations of GOME-2 for East Chinese provinces and surrounding countries. The new emission estimates correspond well with the bottom-up inventory of EDGAR v4.2, but are smaller than the inventories of INTEX-B and MEIC. They reveal a strong positive trend during 2007–2011 for almost all Chinese provinces, related to the country's economic development. We find a 41% increment of NOx emissions in East China during this period, which shows the need to update emission inventories in this region on a regular basis. Negative emission trends are found in Japan and South Korea, which can be attributed to a combined effect of local environmental policy and global economic crises. Analysis of seasonal variation distinguishes between regions with dominant anthropogenic or biogenic emissions. For regions with a mixed anthropogenic and biogenic signature, the opposite seasonality can be used for an estimation of the separate emission contributions. Finally, the non-local concentration/emission relationships calculated by the algorithm are used to quantify the direct effect of regional NOx emissions on tropospheric NO2 concentrations outside the region. For regions such as North Korea and Beijing province, a substantial part of the tropospheric NO2 originates from emissions elsewhere.

  18. Active region upflows. II. Data driven magnetohydrodynamic modelling

    Galsgaard, K.; Madjarska, M. S.; Vanninathan, K.; Huang, Z.; Presmann, M.

    2015-12-01

    Context. Observations of many active regions show a slow systematic outflow/upflow from their edges lasting from hours to days. At present no physical explanation has been proven, while several suggestions have been put forward. Aims: This paper investigates one possible method for maintaining these upflows assuming, that convective motions drive the magnetic field to initiate them through magnetic reconnection. Methods: We use Helioseismic and Magnetic Imager (HMI) data to provide an initial potential 3D magnetic field of the active region NOAA 11123 on 2010 November 13 where the characteristic upflow velocities are observed. A simple 1D hydrostatic atmospheric model covering the region from the photosphere to the corona is derived. Local correlation tracking of the magnetic features in the HMI data is used to derive a proxy for the time dependent velocity field. The time dependent evolution of the system is solved using a resistive 3D magnetohydrodynamic code. Results: The magnetic field contains several null points located well above the photosphere, with their fan planes dividing the magnetic field into independent open and closed flux domains. The stressing of the interfaces between the different flux domains is expected to provide locations where magnetic reconnection can take place and drive systematic flows. In this case, the region between the closed and open flux is identified as the region where observations find the systematic upflows. Conclusions: In the present experiment, the driving only initiates magneto-acoustic waves without driving any systematic upflows at any of the flux interfaces. Movie is available in electronic form at http://www.aanda.org

  19. Magnetic structure of an activated filament in a flaring active region

    Sasso, C; Solanki, S K

    2013-01-01

    While the magnetic field in quiescent prominences has been widely investigated, less is known about the field in activated prominences. We introduce observational results on the magnetic field structure of an activated filament in a flaring active region. We study, in particular, its magnetic structure and line-of-sight flows during its early activated phase, shortly before it displays signs of rotation. We invert the Stokes profiles of the chromospheric He I 10830 A triplet and the photospheric Si I 10827 A line observed in this filament by the VTT on Tenerife. Using these inversion results we present and interpret the first maps of velocity and magnetic field obtained in an activated filament, both in the photosphere and the chromosphere. Up to 5 different magnetic components are found in the chromospheric layers of the filament, while outside the filament a single component is sufficient to reproduce the observations. Magnetic components displaying an upflow are preferentially located towards the centre of...

  20. Patterns of Activity in a Global Model of a Solar Active Region

    Bradshaw, Stephen J

    2016-01-01

    In this work we investigate the global activity patterns predicted from a model active region heated by distributions of nanoflares that have a range of frequencies. What differs is the average frequency of the distributions. The activity patterns are manifested in time lag maps of narrow-band instrument channel pairs. We combine hydrodynamic and forward modeling codes with a magnetic field extrapolation to create a model active region and apply the time lag method to synthetic observations. Our aim is not to reproduce a particular set of observations in detail, but to recover some typical properties and patterns observed in active regions. Our key findings are the following. 1. cooling dominates the time lag signature and the time lags between the channel pairs are generally consistent with observed values. 2. shorter coronal loops in the core cool more quickly than longer loops at the periphery. 3. all channel pairs show zero time lag when the line-of-sight passes through coronal loop foot-points. 4. there ...

  1. VHF radar observations of the dip equatorial E-region during sunset in the Brazilian sector

    C. M. Denardini

    2006-07-01

    Full Text Available Using the RESCO 50 MHz backscatter radar (2.33° S, 44.2° W, DIP: –0.5, at São Luís, Brazil, we obtained Range Time Intensity (RTI maps covering the equatorial electrojet heights during daytime and evening. These maps revealed a scattering region at an altitude of about 108 km during the sunset period. The type of 3-m irregularity region we present here has not been reported before in the literature, to our knowledge. It was mainly observed around the Southern Hemisphere summer-solstice period, under quiet magnetic activity condition. The occurrence of this echo region coincides in local time with the maximum intensity of an evening pre-reversal eastward electric field of the ionospheric F-region. A tentative explanation is proposed here in terms of the theory of the divergence of the equatorial electrojet (EEJ current in the evening ionosphere presented by Haerendel and Eccles (1992, to explain the partial contribution of the divergence to the development of the pre-reversal electric field. The theory predicts an enhanced zonal electric field and hence a vertical electric field below 300 km as a consequence of the EEJ divergence in the evening. The experimental results of the enhanced echoes from the higher heights of the EEJ region seem to provide evidence that the divergence of the EEJ current can indeed be the driver of the observed scattering region.

  2. TRMM/LIS and PR Observations and Thunderstorm Activity

    Ohita, S.; Morimoto, T.; Kawasaki, Z. I.; Ushio, T.

    2005-12-01

    Thunderstorms observed by TRMM/PR and LIS have been investigating, and Lightning Research Group of Osaka University (LRG-OU) has unveiled several interesting features. Correlation between lightning activities and the snow depth of convective clouds may follow the power-five law. The power five law means that the flash density is a function of the snow-depth to power five. The definition of snow depth is the height of detectable cloud tops by TRMM/PR from the climatological freezing level, and it may be equivalent to the length of the portion where the solid phase precipitation particles exist. This is given by examining more than one million convective clouds, and we conclude that the power five law should be universal from the aspect of the statistic. Three thunderstorm active areas are well known as "Three World Chimneys", and those are the Central Africa, Amazon of the South America, and South East Asia. Thunderstorm activities in these areas are expected to contribute to the distribution of thermal energy around the equator to middle latitude regions. Moreover thunderstorm activity in the tropical region is believed to be related with the average temperature of our planet earth. That is why long term monitoring of lightning activity is required. After launching TRMM we have accumulated seven-year LIS observations, and statistics for three world chimneys are obtained. We have recognized the additional lightning active area, and that is around the Maracaibo lake in Venezuera. We conclude that this is because of geographical features of the Maracaibo lake and the continuous easterly trade wind. Lightning Activity during El Niño period is another interesting subject. LRGOU studies thunderstorm occurrences over west Indonesia and south China, and investigates the influence of El Nino on lightning . We compare the statistics between El Nino and non El Nino periods. We learn that the lightning activity during El Niño period is higher than non El Nino period instead

  3. Image patch analysis of sunspots and active regions. II. Clustering via dictionary learning

    Moon, Kevin R; Li, Jimmy J; De Visscher, Ruben; Watson, Fraser; Hero, Alfred O

    2015-01-01

    Separating active regions that are quiet from potentially eruptive ones is a key issue in Space Weather applications. Traditional classification schemes such as Mount Wilson and McIntosh have been effective in relating an active region large scale magnetic configuration to its ability to produce eruptive events. However, their qualitative nature prevents systematic studies of an active region's evolution for example. We introduce a new clustering of active regions that is based on the local geometry observed in Line of Sight magnetogram and continuum images. We use a reduced-dimension representation of an active region that is obtained by factoring (i.e. applying dictionary learning to) the corresponding data matrix comprised of local image patches. Two factorizations can be compared via the definition of appropriate metrics on the resulting factors. The distances obtained from these metrics are then used to cluster the active regions. We find that these metrics result in natural clusterings of active regions...

  4. Armenia as a Regional Centre for Astronomy for Development activities

    Mickaelian, A.

    2015-03-01

    The Byurakan Astrophysical Observatory (BAO, Armenia, http://www.bao.am) are among the candidate IAU Regional Nodes for Astronomy for Development activities. It is one of the main astronomical centers of the former Soviet Union and the Middle East region. At present there are 48 qualified researchers at BAO, including six Doctors of Science and 30 PhDs. Five important observational instruments are installed at BAO, the larger ones being 2.6m Cassegrain (ZTA-2.6) and 1m Schmidt (the one that provided the famous Markarian survey). BAO is regarded as a national scientific-educational center, where a number of activities are being organized, such as: international conferences (4 IAU symposia and 1 IAU colloquium, JENAM-2007, etc.), small workshops and discussions, international summer schools (1987, 2006, 2008 and 2010), and Olympiads. BAO collaborates with scientists from many countries. The Armenian Astronomical Society (ArAS, http://www.aras.am/) is an NGO founded in 2001; it has 93 members and it is rather active in the organization of educational, amateur, popular, promotional and other matters. The Armenian Virtual Observatory (ArVO, http://www.aras.am/Arvo/arvo.htm) is one of the 17 national VO projects forming the International Virtual Observatories Alliance (IVOA) and is the only VO project in the region serving also for educational purposes. A number of activities are planned, such as management, coordination and evaluation of the IAU programs in the area of development and education, establishment of the new IAU endowed lectureship program and organization of seminars and public lectures, coordination and initiation of fundraising activities for astronomy development, organization of regional scientific symposia, conferences and workshops, support to Galileo Teacher Training Program (GTTP), production/publication of educational and promotional materials, etc.

  5. Active Latitude Oscillations Observed on the Sun

    Kilcik, A.; Yurchyshyn, V.; Clette, F.; Ozguc, A.; Rozelot, J.-P.

    2016-04-01

    We investigate periodicities in the mean heliographic latitudes of sunspot groups, called active latitudes, for the past six complete solar cycles (1945 - 2008). For this purpose, the multitaper method and Morlet wavelet analysis were used. We found that solar rotation periodicities (26 - 38 days) are present in active latitudes of both hemispheres for all the investigated cycles (18 to 23). Both in the northern and southern hemispheres, active latitudes drifted toward the equator from the beginning to the end of each cycle and followed an oscillating path. These motions are well described by a second-order polynomial. There are no meaningful periods of between 55 and about 300 days in either hemisphere for all cycles. A periodicity of 300 to 370 days appears in both hemispheres for Cycle 23, in the northern hemisphere for Cycle 20, and in the southern hemisphere for Cycle 18.

  6. Active Latitude Oscillations Observed on the Sun

    Kilcik, A; Clette, F; Ozguc, A; Rozelot, J -P

    2016-01-01

    We investigate periodicities in mean heliographic latitudes of sunspot groups, called active latitudes, for the last six complete solar cycles (1945-2008). For this purpose, the Multi Taper Method and Morlet Wavelet analysis methods were used. We found the following: 1) Solar rotation periodicities (26-38 days) are present in active latitudes of both hemispheres for all the investigated cycles (18 to 23). 2) Both in the northern and southern hemispheres, active latitudes drifted towards the equator starting from the beginning to the end of each cycle by following an oscillating path. These motions are well described by a second order polynomial. 3) There are no meaningful periods between 55 and about 300 days in either hemisphere for all cycles. 4) A 300 to 370 day periodicity appears in both hemispheres for Cycle 23, in the northern hemisphere for Cycle 20, and in the southern hemisphere for Cycle 18.

  7. Regional-Scale Climate Change: Observations and Model Simulations

    Bradley, Raymond S; Diaz, Henry F

    2010-12-14

    This collaborative proposal addressed key issues in understanding the Earth's climate system, as highlighted by the U.S. Climate Science Program. The research focused on documenting past climatic changes and on assessing future climatic changes based on suites of global and regional climate models. Geographically, our emphasis was on the mountainous regions of the world, with a particular focus on the Neotropics of Central America and the Hawaiian Islands. Mountain regions are zones where large variations in ecosystems occur due to the strong climate zonation forced by the topography. These areas are particularly susceptible to changes in critical ecological thresholds, and we conducted studies of changes in phonological indicators based on various climatic thresholds.

  8. The longitude dependence of the dayside F region trough: A detailed model-observation comparison

    The nighttime main F region trough extends into the sunlit afternoon sector. This trough feature exhibits both a strong magnetic activity dependence and a longitude (UT) dependence. Whalen (1987), using International Geophysical Year (IGY) ionosonde data, showed that both of these effects are readily extracted from f0F2 observations. In this study the authors show that the longitude effect is the same as that contained in the Utah State University time-dependent ionospheric model. It arises from the offset of the geomagnetic axis from the geographic axis. The magnetic activity dependency is associated with the westward convection in the afternoon sector. It is also contained in the ionospheric model via the empirical magnetospheric convection model. This one-to-one observational-model agreement is unique; to date no other magnetic activity dependent ionospheric feature has been simulated this systemtically

  9. The Maximum Free Magnetic Energy Allowed in a Solar Active Region

    Moore, Ronald L.; Falconer, David A.

    2009-01-01

    Two whole-active-region magnetic quantities that can be measured from a line-of-sight magnetogram are (sup L) WL(sub SG), a gauge of the total free energy in an active region's magnetic field, and sup L(sub theta), a measure of the active region's total magnetic flux. From these two quantities measured from 1865 SOHO/MDI magnetograms that tracked 44 sunspot active regions across the 0.5 R(sub Sun) central disk, together with each active region's observed production of CMEs, X flares, and M flares, Falconer et al (2009, ApJ, submitted) found that (1) active regions have a maximum attainable free magnetic energy that increases with the magnetic size (sup L) (sub theta) of the active region, (2) in (Log (sup L)WL(sub SG), Log(sup L) theta) space, CME/flare-productive active regions are concentrated in a straight-line main sequence along which the free magnetic energy is near its upper limit, and (3) X and M flares are restricted to large active regions. Here, from (a) these results, (b) the observation that even the greatest X flares produce at most only subtle changes in active region magnetograms, and (c) measurements from MSFC vector magnetograms and from MDI line-of-sight magnetograms showing that practically all sunspot active regions have nearly the same area-averaged magnetic field strength: =- theta/A approximately equal to 300 G, where theta is the active region's total photospheric flux of field stronger than 100 G and A is the area of that flux, we infer that (1) the maximum allowed ratio of an active region's free magnetic energy to its potential-field energy is 1, and (2) any one CME/flare eruption releases no more than a small fraction (less than 10%) of the active region's free magnetic energy. This work was funded by NASA's Heliophysics Division and NSF's Division of Atmospheric Sciences.

  10. The Limit of Free Magnetic Energy in Active Regions

    Moore, Ron; Falconer, David; Sterling, Alphonse

    2012-01-01

    By measuring from active-region magnetograms a proxy of the free energy in the active region fs magnetic field, it has been found previously that (1) there is an abrupt upper limit to the free energy the field can hold that increases with the amount of magnetic field in the active region, the active region fs magnetic flux content, and (2) the free energy is usually near its limit when the field explodes in a CME/flare eruption. That is, explosive active regions are concentrated in a main-sequence path bordering the free-energy ]limit line in (flux content, free-energy proxy) phase space. Here, from measurement of Marshall Space Flight Center vector magnetograms, we find the magnetic condition that underlies the free ]energy limit and the accompanying main sequence of explosive active regions. Using a suitable free ]energy proxy measured from vector magnetograms of 44 active regions, we find that (1) in active regions at and near their free ]energy limit, the ratio of magnetic-shear free energy to the non ]free magnetic energy the potential field would have is approximately 1 in the core field, the field rooted along the neutral line, and (2) this ratio is progressively less in active regions progressively farther below their free ]energy limit. This shows that most active regions in which this core-field energy ratio is much less than 1 cannot be triggered to explode; as this ratio approaches 1, most active regions become capable of exploding; and when this ratio is 1 or greater, most active regions are compelled to explode. From these results we surmise the magnetic condition that determines the free ]energy limit is the ratio of the free magnetic energy to the non-free energy the active region fs field would have were it completely relaxed to its potential ]field configuration, and that this ratio is approximately 1 at the free-energy limit and in the main sequence of explosive active regions.

  11. Active Region Filaments Might Harbor Weak Magnetic Fields

    Díaz Baso, C. J.; Martínez González, M. J.; Asensio Ramos, A.

    2016-05-01

    Recent spectropolarimetric observations of active region filaments have revealed polarization profiles with signatures typical of the strong field Zeeman regime. The conspicuous absence in those observations of scattering polarization and Hanle effect signatures was then pointed out by some authors. This was interpreted as either a signature of mixed “turbulent” field components or as a result of optical thickness. In this article, we present a natural scenario to explain these Zeeman-only spectropolarimetric observations of active region (AR) filaments. We propose a two-component model, one on top of the other. Both components have horizontal fields, with the azimuth difference between them being close to 90°. The component that lies lower in the atmosphere is permeated by a strong field of the order of 600 G, while the upper component has much weaker fields, of the order of 10 G. The ensuing scattering polarization signatures of the individual components have opposite signs, so its combination along the line of sight reduces—and even can cancel out—the Hanle signatures, giving rise to an apparent Zeeman-only profile. This model is also applicable to other chromospheric structures seen in absorption above ARs.

  12. Local Helioseismology of Emerging Active Regions: A Case Study

    Kosovichev, Alexander G; Ilonidis, Stathis

    2016-01-01

    Local helioseismology provides a unique opportunity to investigate the subsurface structure and dynamics of active regions and their effect on the large-scale flows and global circulation of the Sun. We use measurements of plasma flows in the upper convection zone, provided by the Time-Distance Helioseismology Pipeline developed for analysis of solar oscillation data obtained by Helioseismic and Magnetic Imager (HMI) on Solar Dynamics Observatory (SDO), to investigate the subsurface dynamics of emerging active region NOAA 11726. The active region emergence was detected in deep layers of the convection zone about 12 hours before the first bipolar magnetic structure appeared on the surface, and 2 days before the emergence of most of the magnetic flux. The speed of emergence determined by tracking the flow divergence with depth is about 1.4 km/s, very close to the emergence speed in the deep layers. As the emerging magnetic flux becomes concentrated in sunspots local converging flows are observed beneath the for...

  13. Aging worlds in contradiction: gerontological observations in the Mediterranean region

    Hans-Joachim von Kondratowitz

    2015-12-01

    Full Text Available This article discusses the existing and developing aging regimes in the Northern and Southern rim countries of the whole Mediterranean region which are all undergoing considerable social and political transformation processes. It is argued that several eye-opening theoretical interventions for such a gerontological project may lead to some methodological problems and pitfalls, which have to be dealt with productively. Central collective concepts of such an analysis (as the change-oriented "modernization effects" of societal aging and the continuity-oriented gaze at the "unity of the region" have to be reconsidered and ought to be more differentiated in order to allow smaller social entities (such as kinship and community systems and their connectivity to be central orientations for analyzing poverty and care management in old age in the Mediterranean region. How to reconnect such a rather micro-political agenda with large processes and big structures of aging policies in the region however still remains an open question.

  14. Deep Sea Coral National Observation Database, Northeast Region

    National Oceanic and Atmospheric Administration, Department of Commerce — The national database of deep sea coral observations. Northeast version 1.0. * This database was developed by the NOAA NOS NCCOS CCMA Biogeography office as part of...

  15. Coreless Winter Characteristics Observed with Global Positioning System Receivers over Antarctic and Arctic Regions

    Wayan Suparta

    2012-01-01

    Full Text Available Problem statement: The most recent warming trends occurred during the winter in Polar Regions had been attracted many researchers to study its impacts, which might affect the sensitivity of climate prediction in both regions, as well as on a global basis. Approach: The aims of this study were to observe the characteristics of coreless winter events using the GPS meteorology such as the Zenith Tropospheric Delay (ZTD, Precipitable Water Vapor (PWV, the surface meteorology and the solar radiation measurements. The periods of observations were within two years which from January 2008 to December 2009 for Antarctic and from July 2008 to June 2010 for the Arctic. Results: The occurrence of coreless winter had clearly detected in June and January for Antarctic and Arctic, respectively. During the winter period, PWV and ZTD, temperature and relative humidity variations in both regions demonstrate a significant unusual warming peak than with the surface pressure. During this event, the increasing of 1°C of temperature showed that the PWV in Arctic was observed twice larger compared to the Antarctic. Conclusion: The increased PWV during winter suggest that the coreless winters characteristic is signified when advection between the warm or cold air masses over the region tend to increase the formation of cyclonic activity that causes increasing in surface temperature.

  16. Case study of a complex active-region filament eruption

    Yan, X. L.; Qu, Z. Q.; Kong, D. F.; Deng, L. H.; Xue, Z. K.

    2013-09-01

    Context. We investigated a solar active-region filament eruption associated with a C6.6 class flare and a coronal mass ejection (CME) in NOAA active region 08858 on 2000 February 9. Aims: We aim to better understand the relationship between filament eruptions and the associated flares and CMEs. Methods: Using BBSO, SOHO/EIT, and TRACE observational data, we analyzed the process of the active-region filament eruption in the chromosphere and the corona. Using the SOHO/MDI magnetograms, we investigated the change of the magnetic fields in the photosphere. Using the GOES soft X-ray flux and the SOHO/LASCO images, we identified the flare and CME, which were associated with this active-region filament eruption. Results: The brightenings in the chromosphere are a precursor of the filament expansion. The eruption itself can be divided into four phases: In the initial phase, the intertwined bright and dark strands of the filament expand. Then, the bright strands are divided into three parts with different expansion velocity. Next, the erupting filament-carrying flux rope expands rapidly and combines with the lower part of the expanding bright strands. Finally, the filament erupts accompanied by other dark strands overlying the filament.The overlying magnetic loops and the expansion of the filament strands can change the direction of the eruption. Conclusions: The time delay between the velocity peaks of the filament and that of the two parts of the bright strands clearly demonstrates that the breakup of the bright loops tying on the filament into individual strands is important for its eruption. The eruption is a collection of multiple processes that are physically coupled rather than a single process.

  17. Waves from Radar and Optical Observations of the MLT region

    Reid, Iain

    Over the past few years we have developed the Australian MLT radar network and established a Rayleigh Lidar system at Buckland Park (BP). In 2009 we obtained funding for a SuperDARN class radar to be installed at BP. This will occur in 2010. Our interest is in the use of this dual frequency radar (typical operating frequencies are between 8 and 12 MHz) for meteor studies of the MLT region. The relatively low operating frequencies of these radars result in an increase the count rates of detected usable meteors (because count rate is proportional to the square root of the transmitted power, and the wavelength raised to 1.5th power), and hence the quality of the derived winds. Most meteor radars operate in the 30 to 55 MHz frequency range. The height coverage is also extended upwards by using a lower frequency because of the larger initial radius of the meteor trails at greater heights. Data from existing SuperDARN radars is available from the Bruny Island radar in Tasmania (available from 1999 -present), and the Unwin radar in southern NZ (available form 2004 -present). While not ideal because of the limited height discrimination available with these older radars, the results extend the information of the dynamics of the MLT region to latitudes below 50S. Opportunities for siting radars on land in this latitude band are limited, and it is a correspondingly very sparse data region. Preliminary results from the radar network will be presented and discussed.

  18. Radio observations of the peripheral region of the Coma cluster near Coma A

    VLA and WSRT observations are reported for the extended radio source 1253+275 on the periphery of the Coma cluster and for two active Coma radio galaxies within 20 arcmin of 1253+275. The data are presented in contour maps and characterized in detail. Source 1253+275 is shown to be a relic radio galaxy with physical conditions similar to those seen in the external regions (30-50 kpc from the cores) of the two active sources (NGC 4789 and NGC 4827). It is suggested that these regions survived for long periods (400 Myr) after the last acceleration of the radiating electrons because transverse expansion was inhibited by the local intergalactic medium, which has a density comparable to that in other rich clusters of galaxies. 7 references

  19. Solar Activity Studies using Microwave Imaging Observations

    Gopalswamy, Nat

    2016-01-01

    We report on the status of solar cycle 24 based on polar prominence eruptions (PEs) and microwave brightness enhancement (MBE) information obtained by the Nobeyama radioheliograph. The north polar region of the Sun had near-zero field strength for more than three years (2012 to 2015) and ended only in September 2015 as indicated by the presence of polar PEs and the lack of MBE. The zero-polar-field condition in the south started only around 2013, but it ended by June 2014. Thus the asymmetry in the times of polarity reversal switched between cycle 23 and 24. The polar MBE is a good proxy for the polar magnetic field strength as indicated by the high degree of correlation between the two. The cross-correlation between the high- and low-latitude MBEs is significant for a lag of ~5.5 to 7.3 years, suggesting that the polar field of one cycle indicates the sunspot number of the next cycle in agreement with the Babcock-Leighton mechanism of solar cycles. The extended period of near-zero field in the north-polar re...

  20. Multi-Spacecraft Observations of the Auroral Acceleration Region

    Sadeghi, Soheil

    2012-01-01

    The two major agents for producing aurora are generally believed to be the quasi-static parallel electric fields, accelerating electrons in the auroral acceleration region (AAR), and Alfvén waves. The Cluster spacecraft quartet has made multi-spacecraft measurements in the AAR possible for the first time. Four event studies are included and discussed in this thesis, using Cluster data inside and at the top of the AAR, to address various open issues regarding the nature of the quasistatic elec...

  1. Cluster observations of particle acceleration up to supra-thermal energies in the cusp region related to low-frequency wave activity – possible implications for the substorm initiation process

    Vogiatzis, I. I.; Sarris, T. E.; Sarris, E. T.; Santolík, Ondřej; Dandouras, I.; Robert, P.; Fritz, T. A.; Zong, Q.-G.; Zhang, H.

    2008-01-01

    Roč. 26, č. 3 (2008), s. 653-669. ISSN 0992-7689 R&D Projects: GA AV ČR IAA301120601 Grant ostatní: INTAS(XE) 03-51-4132; NASA Goddard Space Flight Center(US) NNX07AI24G; NASA Goddard Space Flight Center(US) NNG04GB98G; NSF(US) 0307319 Institutional research plan: CEZ:AV0Z30420517 Keywords : particle acceleration * cusp region * substorm initiation process Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.660, year: 2008 http://www.ann-geophys.net/26/1665/2008/

  2. The Magnetic Classification of Solar Active Regions 1992-2015

    Jaeggli, S. A.; Norton, A. A.

    2016-03-01

    The purpose of this Letter is to address a blindspot in our knowledge of solar active region (AR) statistics. To the best of our knowledge, there are no published results showing the variation of the Mount Wilson magnetic classifications as a function of solar cycle based on modern observations. We show statistics for all ARs reported in the daily Solar Region Summary from 1992 January 1 to 2015 December 31. We find that the α and β class ARs (including all sub-groups, e.g., βγ, βδ) make up fractions of approximately 20% and 80% of the sample, respectively. This fraction is relatively constant during high levels of activity however, an increase in the α fraction to about 35% and and a decrease in the β fraction to about 65% can be seen near each solar minimum and are statistically significant at the 2σ level. Over 30% of all ARs observed during the years of solar maxima were appended with the classifications γ and/or δ, while these classifications account for only a fraction of a percent during the years near the solar minima. This variation in the AR types indicates that the formation of complex ARs may be due to the pileup of frequent emergence of magnetic flux during solar maximum, rather than the emergence of complex, monolithic flux structures.

  3. Keys to spitzer observations of luminous star forming regions

    F. Boulanger

    2006-01-01

    Full Text Available Observaciones del telescopio espacial Spitzer est an abriendo una nueva perspectiva sobre la formaci on de estrellas masivas en la Galaxia, galaxias cercanas y galaxias infrarrojas. Presentamos resultados de un an alisis de observaciones Spitzer de 30 Dorado junto con im agenes H2 1-0 S(1and Br y espectroscop a infrarroja obtenidas con ISO. Hemos relacionado la distribuci on espacial y espectral de la emisi on infrarroja, con el impacto radiativo y din amico del super c umulo estelar R136 sobre la estructura del medio interestelar y la composici on del polvo. Este an alisis da claves para interpretar las im agenes Spitzer de regiones de formaci on de estrellas masivas y abre perspectivas sobre el impacto de c umulos estelares de alta masa en el medio interestelar.

  4. FIP Bias Evolution in a Decaying Active Region

    Baker, D; Démoulin, P; Yardley, S L; van Driel-Gesztelyi, L; Long, D M; Green, L M

    2015-01-01

    Solar coronal plasma composition is typically characterized by first ionization potential (FIP) bias. Using spectra obtained by Hinode's EUV Imaging Spectrometer (EIS) instrument, we present a series of large-scale, spatially resolved composition maps of active region (AR) 11389. The composition maps show how FIP bias evolves within the decaying AR from 2012 January 4-6. Globally, FIP bias decreases throughout the AR. We analyzed areas of significant plasma composition changes within the decaying AR and found that small-scale evolution in the photospheric magnetic field is closely linked to the FIP bias evolution observed in the corona. During the AR's decay phase, small bipoles emerging within supergranular cells reconnect with the pre-existing AR field, creating a pathway along which photospheric and coronal plasmas can mix. The mixing time scales are shorter than those of plasma enrichment processes. Eruptive activity also results in shifting the FIP bias closer to photospheric in the affected areas. Final...

  5. Sunspot Waves and Triggering of Homologous Active Region Jets

    Chandra, Ramesh; Mulay, Sargam; Tripathi, Durgesh

    2014-01-01

    We present and discuss multi-wavelength observations of five homologous recurrent solar jets that occurred in active region NOAA 11133 on 11 December, 2010. These jets were well observed by the Solar Dynamic observatory (SDO) with high spatial and temporal resolution. The speed of the jets ranged between 86 and 267 km/s. A type III radio burst was observed in association with all the five jets. The investigation of the over all evolution of magnetic field in the source regions suggested that the flux was continuously emerging on longer term. However, all the jets but J5 were triggered during a local dip in the magnetic flux, suggesting the launch of the jets during localised submergence of magnetic flux. Additionally, using the PFSS modelling of the photospheric magnetic field, we found that all the jets were ejected in the direction of open field lines. We also traced sunspot oscillations from the sunspot interior to foot-point of jets and found presence of ~ 3 minute oscillations in all the SDO/AIA passband...

  6. An Active Region Model for Capturing Fractal Flow Patterns inUnsaturated Soils: Model Development

    Liu, Hui-Hai; Zhang, R.; Bodvarsson, Gudmundur S.

    2005-06-11

    Preferential flow commonly observed in unsaturated soils allows rapid movement of solute from the soil surface or vadose zone to the groundwater, bypassing a significant volume of unsaturated soil and increasing the risk of groundwater contamination. A variety of evidence indicates that complex preferential patterns observed from fields are fractals. In this study, we developed a relatively simple active region model to incorporate the fractal flow pattern into the continuum approach. In the model, the flow domain is divided into active and inactive regions. Flow occurs preferentially in the active region (characterized by fractals), and inactive region is simply bypassed. A new constitutive relationship (the portion of the active region as a function of saturation) was derived. The validity of the proposed model is demonstrated by the consistency between field observations and the new constitutive relationship.

  7. HF Doppler observations of vertical plasma drifts in the evening F region at the equator

    Hf Doppler observations of vertical plasma drifts in the evening F region of the equatorial ionosphere at Trivandrum (8.5 degrees N, 77 degrees E; dip 0.9 degrees S) are presented. The observations reveal a consistent pattern characterized by a post-sun-sent enhancement with peak drift velocity in the range 30-60 m s-1 for quiet conditions. Under moderately disturbed conditions, the enhancement is found to be down by as much as a factor of 2, while no such appreciable change is noted for highly disturbed conditions. The pattern of drift velocity dependence on magnetic activity is seen to be consistent with that of spread F occurrence. A striking feature of the observations is the presence of a significant fluctuating component in the drift velocity with quasiperiods ranging from a few minutes to a few tens of minutes during both quiet and disturbing periods

  8. HF Doppler observations of vertical plasma drifts in the evening F region at the equator

    Jayachandran, B.; Balan, N.; Nampoothiri, S.P.; Rao, P.B. (Univ. of Kerala, Trivandrum (India))

    1987-10-01

    Hf Doppler observations of vertical plasma drifts in the evening F region of the equatorial ionosphere at Trivandrum (8.5{degrees}N, 77{degrees}E; dip 0.9{degrees}S) are presented. The observations reveal a consistent pattern characterized by a post-sun-sent enhancement with peak drift velocity in the range 30-60 m s{sup {minus}1} for quiet conditions. Under moderately disturbed conditions, the enhancement is found to be down by as much as a factor of 2, while no such appreciable change is noted for highly disturbed conditions. The pattern of drift velocity dependence on magnetic activity is seen to be consistent with that of spread F occurrence. A striking feature of the observations is the presence of a significant fluctuating component in the drift velocity with quasiperiods ranging from a few minutes to a few tens of minutes during both quiet and disturbing periods.

  9. Narrow-line-width UV bursts in the transition region above Sunspots observed by IRIS

    Hou, Zhenyong; Xia, Lidong; Li, Bo; Madjarska, Maria S; Fu, Hui; Mou, Chaozhou; Xie, Haixia

    2016-01-01

    Various small-scale structures abound in the solar atmosphere above active regions, playing an important role in the dynamics and evolution therein. We report on a new class of small-scale transition region structures in active regions, characterized by strong emissions but extremely narrow Si IV line profiles as found in observations taken with the Interface Region Imaging Spectrograph (IRIS). Tentatively named as Narrow-line-width UV bursts (NUBs), these structures are located above sunspots and comprise of one or multiple compact bright cores at sub-arcsecond scales. We found six NUBs in two datasets (a raster and a sit-and-stare dataset). Among these, four events are short-living with a duration of $\\sim$10 mins while two last for more than 36 mins. All NUBs have Doppler shifts of 15--18 km/s, while the NUB found in sit-and-stare data possesses an additional component at $\\sim$50 km/s found only in the C II and Mg II lines. Given that these events are found to play a role in the local dynamics, it is impo...

  10. Image patch analysis of sunspots and active regions. I. Intrinsic dimension and correlation analysis

    Moon, Kevin R; Delouille, Veronique; De Visscher, Ruben; Watson, Fraser; Hero, Alfred O

    2015-01-01

    Complexity of an active region is related to its flare-productivity. Mount Wilson or McIntosh sunspot classifications measure such complexity but in a categorical way, and may therefore not use all the information present in the observations. Moreover, such categorical schemes hinder a systematic study of an active region's evolution for example. We propose fine-scale quantitative descriptors for an active region's complexity and relate them to the Mount Wilson classification. We analyze the local correlation structure within continuum and magnetogram data, as well as the cross-correlation between continuum and magnetogram data. We compute the intrinsic dimension, partial correlation, and canonical correlation analysis (CCA) of image patches of continuum and magnetogram active region images taken from the SOHO-MDI instrument. We use masks of sunspots derived from continuum as well as larger masks of magnetic active regions derived from the magnetogram to analyze separately the core part of an active region fr...

  11. A Fractal Dimension Survey of Active Region Complexity

    McAteer, R. T. James; Gallagher, Peter; Ireland, Jack

    2005-01-01

    A new approach to quantifying the magnetic complexity of active regions using a fractal dimension measure is presented. This fully-automated approach uses full disc MDI magnetograms of active regions from a large data set (2742 days of the SoHO mission; 9342 active regions) to compare the calculated fractal dimension to both Mount Wilson classification and flare rate. The main Mount Wilson classes exhibit no distinct fractal dimension distribution, suggesting a self-similar nature of all active regions. Solar flare productivity exhibits an increase in both the frequency and GOES X-ray magnitude of flares from regions with higher fractal dimensions. Specifically a lower threshold fractal dimension of 1.2 and 1.25 exists as a necessary, but not sufficient, requirement for an active region to produce M- and X-class flares respectively .

  12. Regional Arctic observations of TEC gradients and scintillations

    Durgonics, Tibor; Høeg, Per; von Benzon, Hans-Henrik

    2015-01-01

    There has been a growing scientific interest in the Arctic ionospheric properties and variations during the recentyears. However, our understanding of the fundamental ionospheric processes present in this area is still incomplete.Today GNSS networks present in Greenland make it possible to acquire...... near-real time observations of the stateand variations of the high-latitude ionosphere. This data can be employed to obtain relevant geophysical variablesand statistics. In our study GPS-derived total electron content (TEC) measurements have been complemented with amplitudescintillation indices (S4......), and phase scintillation indices (σϕ) The investigation of relations of these geophysical variables can lead to possible new ways to study the underlying processes and to build tools for monitoring and predicting Arctic TEC and scintillation large-scale patterns. A number of specific ionosphere events...

  13. Optical polarization observations in the Scorpius region: NGC 6124

    Vergne, M Marcela; Martinez, Ruben; Orsatti, Ana Maria; Alvarez, Maria Paula

    2010-01-01

    We have obtained optical multicolour (UBVRI) linear polarimetric data for 46 of the brightest stars in the area of the open cluster NGC 6124 in order to investigate the properties of the interstellar medium (ISM) that lies along the line of sight toward the cluster. Our data yield a mean polarization efficiency of $P_V/E_{B-V}=3.1\\pm$0.62, i.e., a value lower than the polarization produced by the ISM with normal efficiency for an average color excess of $E_{B-V}=0.80$ as that found for NGC 6124. Besides, the polarization shows an orientation of $\\theta \\sim 8^\\circ$.1 which is not parallel to the Galactic Disk,an effect that we think may be caused by the Lupus Cloud. Our analysis also indicates that the observed visual extinction in NGC 6124 is caused by the presence of three different absorption sheets located between the Sun and NGC 6124. The values of the internal dispersion of the polarization ($\\Delta P_V\\sim 1.3% $) and of the colour excess ($\\Delta E_{B-V}\\sim 0.29$ mag) for the members of NGC 6124 see...

  14. ON THE ROLE OF ROTATING SUNSPOTS IN THE ACTIVITY OF SOLAR ACTIVE REGION NOAA 11158

    We study the role of rotating sunspots in relation to the evolution of various physical parameters characterizing the non-potentiality of the active region (AR) NOAA 11158 and its eruptive events using the magnetic field data from the Helioseismic and Magnetic Imager (HMI) and multi-wavelength observations from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory. From the evolutionary study of HMI intensity and AIA channels, it is observed that the AR consists of two major rotating sunspots, one connected to a flare-prone region and another with coronal mass ejection (CME). The constructed space-time intensity maps reveal that the sunspots exhibited peak rotation rates coinciding with the occurrence of major eruptive events. Further, temporal profiles of twist parameters, namely, average shear angle, αav, αbest, derived from HMI vector magnetograms, and the rate of helicity injection, obtained from the horizontal flux motions of HMI line-of-sight magnetograms, correspond well with the rotational profile of the sunspot in the CME-prone region, giving predominant evidence of rotational motion causing magnetic non-potentiality. Moreover, the mean value of free energy from the virial theorem calculated at the photospheric level shows a clear step-down decrease at the onset time of the flares revealing unambiguous evidence of energy release intermittently that is stored by flux emergence and/or motions in pre-flare phases. Additionally, distribution of helicity injection is homogeneous in the CME-prone region while in the flare-prone region it is not and often changes sign. This study provides a clear picture that both proper and rotational motions of the observed fluxes played significant roles in enhancing the magnetic non-potentiality of the AR by injecting helicity, twisting the magnetic fields and thereby increasing the free energy, leading to favorable conditions for the observed transient activity.

  15. ON THE ROLE OF ROTATING SUNSPOTS IN THE ACTIVITY OF SOLAR ACTIVE REGION NOAA 11158

    Vemareddy, P.; Ambastha, A. [Udaipur Solar Observatory, Physical Research Laboratory, Udaipur-313001 (India); Maurya, R. A., E-mail: vema@prl.res.in, E-mail: ambastha@prl.res.in, E-mail: ramajor@astro.snu.ac.kr [Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of)

    2012-12-10

    We study the role of rotating sunspots in relation to the evolution of various physical parameters characterizing the non-potentiality of the active region (AR) NOAA 11158 and its eruptive events using the magnetic field data from the Helioseismic and Magnetic Imager (HMI) and multi-wavelength observations from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory. From the evolutionary study of HMI intensity and AIA channels, it is observed that the AR consists of two major rotating sunspots, one connected to a flare-prone region and another with coronal mass ejection (CME). The constructed space-time intensity maps reveal that the sunspots exhibited peak rotation rates coinciding with the occurrence of major eruptive events. Further, temporal profiles of twist parameters, namely, average shear angle, {alpha}{sub av}, {alpha}{sub best}, derived from HMI vector magnetograms, and the rate of helicity injection, obtained from the horizontal flux motions of HMI line-of-sight magnetograms, correspond well with the rotational profile of the sunspot in the CME-prone region, giving predominant evidence of rotational motion causing magnetic non-potentiality. Moreover, the mean value of free energy from the virial theorem calculated at the photospheric level shows a clear step-down decrease at the onset time of the flares revealing unambiguous evidence of energy release intermittently that is stored by flux emergence and/or motions in pre-flare phases. Additionally, distribution of helicity injection is homogeneous in the CME-prone region while in the flare-prone region it is not and often changes sign. This study provides a clear picture that both proper and rotational motions of the observed fluxes played significant roles in enhancing the magnetic non-potentiality of the AR by injecting helicity, twisting the magnetic fields and thereby increasing the free energy, leading to favorable conditions for the observed transient activity.

  16. Software Displays Data on Active Regions of the Sun

    Golightly, Mike; Weyland, Mark; Raben, Vern

    2011-01-01

    The Solar Active Region Display System is a computer program that generates, in near real time, a graphical display of parameters indicative of the spatial and temporal variations of activity on the Sun. These parameters include histories and distributions of solar flares, active region growth, coronal mass ejections, size, and magnetic configuration. By presenting solar-activity data in graphical form, this program accelerates, facilitates, and partly automates what had previously been a time-consuming mental process of interpretation of solar-activity data presented in tabular and textual formats. Intended for original use in predicting space weather in order to minimize the exposure of astronauts to ionizing radiation, the program might also be useful on Earth for predicting solar-wind-induced ionospheric effects, electric currents, and potentials that could affect radio-communication systems, navigation systems, pipelines, and long electric-power lines. Raw data for the display are obtained automatically from the Space Environment Center (SEC) of the National Oceanic and Atmospheric Administration (NOAA). Other data must be obtained from the NOAA SEC by verbal communication and entered manually. The Solar Active Region Display System automatically accounts for the latitude dependence of the rate of rotation of the Sun, by use of a mathematical model that is corrected with NOAA SEC active-region position data once every 24 hours. The display includes the date, time, and an image of the Sun in H light overlaid with latitude and longitude coordinate lines, dots that mark locations of active regions identified by NOAA, identifying numbers assigned by NOAA to such regions, and solar-region visual summary (SRVS) indicators associated with some of the active regions. Each SRVS indicator is a small pie chart containing five equal sectors, each of which is color-coded to provide a semiquantitative indication of the degree of hazard posed by one aspect of the activity at

  17. Cloud condensation nuclei activity and droplet activation kinetics of wet processed regional dust samples and minerals

    P. Kumar

    2011-08-01

    Full Text Available This study reports laboratory measurements of particle size distributions, cloud condensation nuclei (CCN activity, and droplet activation kinetics of wet generated aerosols from clays, calcite, quartz, and desert soil samples from Northern Africa, East Asia/China, and Northern America. The dependence of critical supersaturation, sc, on particle dry diameter, Ddry, is used to characterize particle-water interactions and assess the ability of Frenkel-Halsey-Hill adsorption activation theory (FHH-AT and Köhler theory (KT to describe the CCN activity of the considered samples. Wet generated regional dust samples produce unimodal size distributions with particle sizes as small as 40 nm, CCN activation consistent with KT, and exhibit hygroscopicity similar to inorganic salts. Wet generated clays and minerals produce a bimodal size distribution; the CCN activity of the smaller mode is consistent with KT, while the larger mode is less hydrophilic, follows activation by FHH-AT, and displays almost identical CCN activity to dry generated dust. Ion Chromatography (IC analysis performed on regional dust samples indicates a soluble fraction that cannot explain the CCN activity of dry or wet generated dust. A mass balance and hygroscopicity closure suggests that the small amount of ions (from low solubility compounds like calcite present in the dry dust dissolve in the aqueous suspension during the wet generation process and give rise to the observed small hygroscopic mode. Overall these results identify an artifact that may question the atmospheric relevance of dust CCN activity studies using the wet generation method.

    Based on the method of threshold droplet growth analysis, wet generated mineral aerosols display similar activation kinetics compared to ammonium sulfate calibration aerosol. Finally, a unified CCN activity framework that accounts for concurrent effects of solute and adsorption is developed to

  18. Behaviour of oscillations in loop structures above active regions

    Kolobov, D Y; Chelpanov, A A; Kochanov, A A; Anfinogentov, S A; Chupin, S A; Myshyakov, I I; Tomin, V E

    2015-01-01

    In this study we combine the multiwavelength ultraviolet -- optical (Solar Dynamics Observatory, SDO) and radio (Nobeyama Radioheliograph, NoRH) observations to get further insight into space-frequency distribution of oscillations at different atmospheric levels of the Sun. We processed the observational data on NOAA 11711 active region and found oscillations propagating from the photospheric level through the transition region upward into the corona. The power maps of low-frequency (1--2 mHz) oscillations reproduce well the fan-like coronal structures visible in the Fe ix 171A line. High frequency oscillations (5--7 mHz) propagate along the vertical magnetic field lines and concentrate inside small-scale elements in the umbra and at the umbra-penumbra boundary. We investigated the dependence of the dominant oscillation frequency upon the distance from the sunspot barycentre to estimate inclination of magnetic tubes in higher levels of sunspots where it cannot be measured directly, and found that this angle i...

  19. Two types of ion energy dispersions observed in the nightside auroral regions during geomagnetically disturbed periods

    Hirahara, M.; Mukai, T.; Nagai, T.; Kaya, N.; Hayakawa, H.; Fukunishi, H.

    1996-04-01

    The Akebono satellite has observed two types of energy dispersion signatures of discrete ion precipitation event in the nightside auroral regions during active geomagnetic conditions. The charged particle experiments and electric and magnetic field detectors on board Akebono provide us with essential clues to characterize the source regions and acceleration and/or injection processes associated with these two types of ion signatures. The magnetic field data obtained simultaneously by the geosynchronous GOES 6 and 7 satellites and the ground magnetograms are useful to examine their relationships with geomagnetic activity. Mass composition data and pitch angle distributions show that different sources and processes should be attributed to two types (Types I and II) of energy dispersion phenomena. Type I consists of multiple bouncing ion clusters constituted by H+. These H+ clusters tend to be detected at the expansion phase of substorms and have characteristic multiple energy-dispersed signatures. Type II consists of O+ energy dispersion(s), which is often observed at the recovery phase. It is reasonable to consider that the H+ clusters of Type I are accelerated by dipolarization at the equator, are injected in the field-aligned direction, and bounce on closed field lines after the substorm onset. We interpret these multiple energy dispersion events as mainly due to the time-of-flight (TOF) effect, although the convection may influence the energy-dispersed traces. Based of the TOF model, we estimate the source distance to be 20-30 RE along the field lines. On the other hand, the O+ energy dispersion of Type II is a consequence of reprecipitation of terrestrial ions ejected as an upward flowing ion (UFI) beam from the upper ionosphere by a parallel electrostatic potential difference. The O+ energy dispersion is induced by the E×B drift during the field-aligned transport from the source region to the observation point.

  20. High power VCSEL device with periodic gain active region

    Ning, Y. Q., II; Qin, L.; Sun, Y. F.; Li, T.; Cui, J. J.; Peng, B.; Liu, G. Y.; Zhang, Y.; Liu, Y.; Wang, L. J.; Cui, D. F.; Xu, Z. Y.

    2007-11-01

    High power vertical cavity surface emitting lasers with large aperture have been fabricated through improving passivation, lateral oxidation and heat dissipation techniques. Different from conventional three quantum well structure, a periodic gain active region with nine quantum wells was incorporated into the VCSEL structure, with which high efficiency and high power operation were expected. The nine quantum wells were divided into three groups with each of them located at the antinodes of the cavity to enhance the coupling between the optical field and the gain region. Large aperture and bottom-emitting configuration was used to improve the beam quality and the heat dissipation. A maximum output power of 1.4W was demonstrated at CW operation for a 400μm-diameter device. The lasing wavelength shifted to 995.5nm with a FWHM of 2nm at a current of 4.8A due to the internal heating and the absence of active water cooling. A ring-shape farfield pattern was induced by the non-homogeneous lateral current distribution in large diameter device. The light intensity at the center of the ring increased with increasing current. A symmetric round light spot at the center and single transverse mode operation with a divergence angle of 16° were observed with current beyond 4.8A.

  1. Research on the Dividing Method for Present-Day Regional Active Block

    Zhang Xiaoliang; Jiang Zaisen; Chen Bing; Wang Qi; Zhang Xi

    2006-01-01

    In this paper, a new idea that combines Quasi-Accurate Detection of gross errors (QUAD) with discontinuous deformation positive analysis, is brought forward to divide the regional active blocks. The method can improve the demarcation of active blocks for areas lacking with observation data and offer a new train of through for the complete study of the regional deformation of active blocks. In addition, using the Sichuan-Yunnan area as example, the practice process of the method is introduced briefly.

  2. Flare activity, sunspot motions, and the evolution of vector magnetic fields in Hale region 17244

    Neidig, Donald F.; Hagyard, Mona J.; Machado, Marcos E.; Smith, Jesse B., Jr.

    1986-01-01

    The magnetic and dynamical circumstances leading to the 1B/M4 flare of November 5, 1980 are studied, and a strong association is found between the buildup of magnetic shear and the onset of flare activity within the active region. The development of shear, as observed directly in vector magnetograms, is consistent in detail with the dynamical history of the active region and identifies the precise location of the optical and hard-X-ray kernels of the flare emission.

  3. Improve earthquake hypocenter using adaptive simulated annealing inversion in regional tectonic, volcano tectonic, and geothermal observation

    Ry, Rexha Verdhora, E-mail: rexha.vry@gmail.com [Master Program of Geophysical Engineering, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Jalan Ganesha No.10, Bandung 40132 (Indonesia); Nugraha, Andri Dian, E-mail: nugraha@gf.itb.ac.id [Global Geophysical Research Group, Faculty of Mining and Petroleum Engineering, Institut Teknologi Bandung, Jalan Ganesha No.10, Bandung 40132 (Indonesia)

    2015-04-24

    Observation of earthquakes is routinely used widely in tectonic activity observation, and also in local scale such as volcano tectonic and geothermal activity observation. It is necessary for determining the location of precise hypocenter which the process involves finding a hypocenter location that has minimum error between the observed and the calculated travel times. When solving this nonlinear inverse problem, simulated annealing inversion method can be applied to such global optimization problems, which the convergence of its solution is independent of the initial model. In this study, we developed own program codeby applying adaptive simulated annealing inversion in Matlab environment. We applied this method to determine earthquake hypocenter using several data cases which are regional tectonic, volcano tectonic, and geothermal field. The travel times were calculated using ray tracing shooting method. We then compared its results with the results using Geiger’s method to analyze its reliability. Our results show hypocenter location has smaller RMS error compared to the Geiger’s result that can be statistically associated with better solution. The hypocenter of earthquakes also well correlated with geological structure in the study area. Werecommend using adaptive simulated annealing inversion to relocate hypocenter location in purpose to get precise and accurate earthquake location.

  4. Improve earthquake hypocenter using adaptive simulated annealing inversion in regional tectonic, volcano tectonic, and geothermal observation

    Observation of earthquakes is routinely used widely in tectonic activity observation, and also in local scale such as volcano tectonic and geothermal activity observation. It is necessary for determining the location of precise hypocenter which the process involves finding a hypocenter location that has minimum error between the observed and the calculated travel times. When solving this nonlinear inverse problem, simulated annealing inversion method can be applied to such global optimization problems, which the convergence of its solution is independent of the initial model. In this study, we developed own program codeby applying adaptive simulated annealing inversion in Matlab environment. We applied this method to determine earthquake hypocenter using several data cases which are regional tectonic, volcano tectonic, and geothermal field. The travel times were calculated using ray tracing shooting method. We then compared its results with the results using Geiger’s method to analyze its reliability. Our results show hypocenter location has smaller RMS error compared to the Geiger’s result that can be statistically associated with better solution. The hypocenter of earthquakes also well correlated with geological structure in the study area. Werecommend using adaptive simulated annealing inversion to relocate hypocenter location in purpose to get precise and accurate earthquake location

  5. The Impact of Resolution on Observed HII Region Properties from WFPC2 Observations of M101

    Pleuss, P O; Fricke, K J

    2000-01-01

    Two continuum subtracted H-alpha HST frames of M101 are used to determine the positions, angular sizes and absolute fluxes of 237 HII regions using a semi-automated technique. From these we have constructed the luminosity and diameter distribution functions. We repeat this process on the images after artificially reducing the linear resolution to that typically obtained with ground based imaging. We find substantial differences in the luminosity function and diameter distribution. The measured internal properties, such as central surface brightness and radial gradient are dominated by the PSF at linear resolutions less than roughly 40 pc FWHM. From the ground such resolutions are currently only obtainable for the nearest galaxies. We find evidence for two regimes of clustering of the HII regions and diffuse emission, suggesting two different regimes of star formation in late type spiral galaxies. This property in combination with the blending that occurs at ground based resolutions might be responsible for th...

  6. Optimization of NOx emissions in Yangtze Delta Region using in-situ observations

    Wang, Hengmao; Jiang, Fei; Jiang, Ziqiang; Liu, Jane; Chen, Jing Ming; Ju, Weimin

    2016-04-01

    Well quantified NOx emissions are essential for air quality forecasting and air pollution mitigation. The traditional "bottom-up" estimates of NOx emissions, using activity data and emission factors, are subject to large uncertainties, especially in China. Inverse modelling, often referred to as "top-down" approach, using atmospheric observations made from satellites and ground stations, provides an effective means to optimize bottom-up NOx emission inventory. The rapid expansion of air quality monitoring network in China offers an opportunity to constrain NOx emissions using in-situ ground measurements. We explore the potential of using NO2 observations from the air quality monitoring network to improve NOx emissions estimates in China. The four dimensional variational data assimilation (4DVAR) scheme in the Community Multi-scale Air Quality (CMAQ) adjoint model is implemented to infer NOx emissions in Yangtze Delta Region at 12 km resolution. The optimized NOx emissions are presented. The uncertainly reduction of estimates is analyzed and discussed.

  7. Millimetre continuum observations of southern massive star formation regions. I. SIMBA observations of cold cores

    Hill, T; Minier, V; Thompson, M A; Walsh, A J; Hunt-Cunningham, M; Garay, G

    2005-01-01

    We report the results of a SEST 1.2 mm continuum emission survey toward regions previously identified as harbouring a methanol maser and/or an UC HII region, typically indicative of massive star formation. Emission is detected toward all of the methanol maser and UC HII regions targeted, implying that these objescts are associated with cold, deeply embedded objects. We have also identified a large number (253) of sources within the SIMBA maps, which are devoid of maser and radio continuum emission. These `mm-only' cores may be an entirely new class of source that represents an earlier stage in the evolution of massive stars, prior to the onset of methanol maser emission. Or, they may harbour protoclusters, which do not contain any high mass stars (i.e. below the HII). Alternatively, they may represent a cross-section of both, where the more massive mm-only cores are a precursor to the methanol maser and the least massive mm-only cores will form intermediate mass stars. Analysis of the mm-only sources shows th...

  8. Supply and demand analysis of leisure activities in selected region

    Helcl, Petr

    2014-01-01

    The Thesis on the topic "Supply and demand analysis of leisure activities in the region," focuses on the forms of spending free time in the selected region. The theoretical part deals with the study of scientific publications focusing on leisure and leisure education. The economic concepts are examined to define the work, factors affecting leisure adults and content of leisure activities and leisure educational activities. The legal system of the Czech Republic defining the possibilities of a...

  9. Flare Footpoint Regions and a Surge Observed by the Hinode/EUV Imaging Spectrometer (EIS), RHESSI, and SDO/AIA

    Doschek, George A; Dennis, Brian R; Reep, Jeffrey W; Caspi, Amir

    2015-01-01

    The Extreme-ultraviolet Imaging Spectrometer (EIS) on the Hinode spacecraft observed flare footpoint regions coincident with a surge for a M3.7 flare observed on 25 September 2011 at N12 E33 in active region 11302. The flare was observed in spectral lines of O VI, Fe X, Fe XII, Fe XIV, Fe XV, Fe XVI, Fe XVII, Fe XXIII and Fe XXIV. The EIS observations were made coincident with hard X-ray bursts observed by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI). Overlays of the RHESSI images on the EIS raster images at different wavelengths show a spatial coincidence of features in the RHESSI images with the EIS upflow and downflow regions, as well as loop-top or near-loop-top regions. A complex array of phenomena was observed including multiple evaporation regions and the surge, which was also observed by the Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) telescopes. The slit of the EIS spectrometer covered several flare footpoint regions from which evaporative upflows in Fe XX...

  10. Chromospheric magnetic fields of an active region filament

    Xu, Z.; Solanki, S.; Lagg, A.

    2012-06-01

    Vector magnetic fields of an active region filament are co-spatially and co-temporally mapped in photosphere and upper chromosphere, by using spectro-polarimetric observations made by Tenerife Infrared Polarimeter (TIP II) at the German Vacuum Tower Telescope (VTT). A Zeeman-based ME inversion is performed on the full Stokes vectors of both the photospheric Si I 1082.7 nm and the chromospheric He I 1083.0 nm lines. We found that the strong magnetic fields, with the field strength of 600 - 800 G in the He I line formation height, are not uncommon among AR filaments. But such strong magnetic field is not always found in AR filaments.

  11. On the Role of Rotating Sunspots in the Activity of Solar Active Region NOAA 11158

    Vemareddy, P; Maurya, R A

    2012-01-01

    We study the role of rotating sunspots in relation to the evolution of various physical parameters characterizing the non-potentiality of the active region NOAA 11158 and its eruptive events using the magnetic field data from the Helioseismic and Magnetic Imager (HMI) and multi-wavelength observations from the Atmospheric Imaging Assembly (AIA) on board Solar Dynamics Observatory (SDO). From the evolutionary study of HMI intensity and AIA channels, it is observed that the AR consists of two major rotating sunspots one connected to flare-prone region and another with CME. The constructed space-time intensity maps reveal that the sunspots exhibited peak rotation rates coinciding with the occurrence of the major eruptive events. Further, temporal profiles of twist parameters, viz., average shear angle, $\\alpha_{\\rm av}$, $\\alpha_{\\rm best}$, derived from HMI vector magnetograms and the rate of helicity injection, obtained from the horizontal flux motions of HMI line-of-sight magnetograms, corresponded well with ...

  12. Instant Stereoscopic Tomography of Active Regions with STEREO/EUVI

    Aschwanden, M. J.; Wuelser, J.; Nitta, N.; Lemen, J.; Sandman, A.

    2008-12-01

    We develop a novel 3D reconstruction method of the coronal plasma of an active region by combining stereoscopic triangulation of loops with density and temperature modeling of coronal loops with a filling factor equivalent to tomographic volume rendering. Because this method requires only a stereoscopic image pair in multiple temperature filters, which are sampled within ~1 minute with the recent STEREO/EUVI instrument, this method is about 4 orders of magnitude faster than conventional solar rotation-based tomography. We reconstruct the 3D density and temperature distribution of active region NOAA 10955 by stereoscopic triangulation of 70 loops, which are used as a skeleton for a 3D field interpolation of some 7000 loop components, leading to a 3D model that reproduces the observed fluxes in each stereosocpic image pair with an accuracy of a few percent (of the average flux) in each pixel. With the stereoscopic tomography we infer also a differential emission measure (DEM) distribution over the entire temperature range of T~0.01-10 MK, with predictions for the transition region and hotter corona in soft X-rays. The tomographic 3D model provides also large statistics of physical parameters. We find that the EUV loops with apex temperatures of T = 1- 3 MK tend to be super-hydrostatic, while hotter loops with T = 4-7 MK are near-hydrostatic. The new 3D reconstruction model is fully independent of any magnetic field data and is promising for future tests of theoretical magnetic field models and coronal heating models.

  13. Increased premotor cortex activation in high functioning autism during action observation.

    Perkins, Tom J; Bittar, Richard G; McGillivray, Jane A; Cox, Ivanna I; Stokes, Mark A

    2015-04-01

    The mirror neuron (MN) hypothesis of autism has received considerable attention, but to date has produced inconsistent findings. Using functional MRI, participants with high functioning autism or Asperger's syndrome were compared to typically developing individuals (n=12 in each group). Participants passively observed hand gestures that included waving, pointing, and grasping. Concerning the MN network, both groups activated similar regions including prefrontal, inferior parietal and superior temporal regions, with the autism group demonstrating significantly greater activation in the dorsal premotor cortex. Concerning other regions, participants with autism demonstrated increased activity in the anterior cingulate and medial frontal gyrus, and reduced activation in calcarine, cuneus, and middle temporal gyrus. These results suggest that during observation of hand gestures, frontal cortex activation is affected in autism, which we suggest may be linked to abnormal functioning of the MN system. PMID:25726458

  14. Strong Earthquake Activity and Its Relation to Regional Neotectonic Movement in Sichuan-Yunnan Region

    Su Youjin; Qin Jiazheng

    2001-01-01

    Based on analyzing space inhomogeneous image of strong earthquake activity, the image of source rupture and the mechanical property of the source fault in Sichuan-Yunnan region, the relations among the strong earthquake activity, active fault, modern movement status of active blocks and structural background of the deep media have been discussed, and the characteristics of strong earthquake activity and possible mechanism have been also discussed.

  15. Active-region designs in quantum cascade lasers

    This paper analyses the development of active-region designs in quantum cascade lasers. Active-region designs have been demonstrated to date that employ various radiative transitions (vertical, diagonal, interminiband and interband). The lower laser level is depopulated through nonradiative transitions, such as one- or two-phonon (and even three-phonon) relaxation or bound state → continuum transitions. Advances in active-region designs and energy diagram optimisation in the past few years have led to significant improvements in important characteristics of quantum cascade lasers, such as their output power, emission bandwidth, characteristic temperature and efficiency. (invited paper)

  16. Slow magnetosonic waves and fast flows in active region loops

    Ofman, Leon; Davila, Joseph M

    2012-01-01

    Recent EUV spectroscopic observations indicate that slow magnetosonic waves are present in active region (AR) loops. Some of the spectral data were also interpreted as evidence of fast (~100-300 km/s) quasi-periodic flows. We have performed three-dimensional magnetohydrodynamic (3D MHD) modeling of a bipolar AR that contains impulsively generated waves and flows in coronal loops. The model AR is initiated with a dipole magnetic field and gravitationally stratified density, with an upflow driven steadily or periodically in localized regions at the footpoints of magnetic loops. The resulting flows along the magnetic field lines of the AR produce higher density loops compared to the surrounding plasma by injection of material into the flux-tubes and the establishment of siphon flow. We find that the impulsive onset of flows with subsonic speeds result in the excitation of damped slow magnetosonic waves that propagate along the loops and coupled nonlinearly driven fast mode waves. The phase speed of the slow magn...

  17. Recent earthquake activity in Trichonis region and its tectonic significance

    N. DELIBASIS

    1977-06-01

    Full Text Available SUMMARY. - The aftershock activity associated with the central Greece
    (Trichonis Lake earthquake of |une-Dec. 1975, has been studied, with emphasis
    on the time and magnitude distribution. It has been found that the value of b,
    in Gutenberg - R i c h t e r ' s relationship was near the same for the primary as
    well as the secondary or second order aftershocks of the sequences, but depends
    upon the focal depth.
    A correlation between the calculated focal mechanisms and the associated
    stress components to the distribution pattern of meizoseismic effects as well
    as to the geological structure of the seismic region was found.
    The seismic region lies at the top of an anticline which was found moving
    downwards, apparently due to compressional stresses.
    Within the series of three earthquakes the progress of the destruction of
    the buildings was observed and reported. The interest is concentrated to modern
    buildings out of reinforced concrete and infill brick walls. The relatively unexpected
    rather bad performance of the later case of buildings was compared to that
    of the traditional small houses out of brick or stone masonry, the behaviour of
    which may be considered as better from what it was expected.

  18. SUMER observations of the inverse Evershed effect in the transition region above a sunspot

    Teriaca, L; Solanki, S K; 10.1051/0004-6361:200810209

    2009-01-01

    Aims. We analyse SUMER spectral scans of a large sunspot within active region NOAA 10923, obtained on 14-15 November 2006, to determine the morphology and dynamics of the sunspot atmosphere at different heights/temperatures. Methods: The data analysed here consist of spectroheliograms in the continuum around 142.0 nm and in the Si iv 140.2 nm, O iii 70.3 nm, N iv 76.5 nm, and O iv 79.0 nm spectral lines. Gaussian-fitting of the observed profiles provides line-of-sight velocity and Doppler-width maps. Results: The data show an asymmetric downflow pattern compatible with the presence of the inverse Evershed flow in a region within roughly twice the penumbral radius at transition-region temperatures up to 0.18 MK. The motions, highly inhomogeneous on small scales, seem to occur in a collar of radially directed filamentary structures, with an average width less than the 1 Mm spatial resolution of SUMER and characterised by different plasma speeds. Assuming that the flows are directed along the field lines, we ded...

  19. Active Ageing Level of Older Persons: Regional Comparison in Thailand

    Md. Nuruzzaman Haque

    2016-01-01

    Full Text Available Active ageing level and its discrepancy in different regions (Bangkok, Central, North, Northeast, and South of Thailand have been examined for prioritizing the policy agenda to be implemented. Attempt has been made to test preliminary active ageing models for Thai older persons and hence active ageing index (AAI, ranges from 0 to 1 has been estimated. Using nationally representative data and confirmatory factor analysis approach, this study justified active ageing models for female and male older persons in Thailand. Results revealed that active ageing level of Thai older persons is not high (mean AAIs for female and male older persons are 0.64 and 0.61, resp., and those are significantly different (p<0.001. Mean AAI in Central region is lower than North, Northeast, and South regions but there is no significant difference in the latter three regions of Thailand. Special emphasis should be given to Central region and policy should be undertaken for increasing active ageing level. Implementation of an Integrated Active Ageing Package (IAAP, containing policies for older persons to improve their health and economic security, to promote participation in social groups and longer working lives, and to arrange learning programs, would be helpful for increasing older persons’ active ageing level in Thailand.

  20. Active Ageing Level of Older Persons: Regional Comparison in Thailand

    Md. Nuruzzaman Haque

    2016-01-01

    Active ageing level and its discrepancy in different regions (Bangkok, Central, North, Northeast, and South) of Thailand have been examined for prioritizing the policy agenda to be implemented. Attempt has been made to test preliminary active ageing models for Thai older persons and hence active ageing index (AAI, ranges from 0 to 1) has been estimated. Using nationally representative data and confirmatory factor analysis approach, this study justified active ageing models for female and male...

  1. Mining activity, income inequality and gender in regional Australia

    Reeson, Andrew; Thomas G Measham; Hosking, Karin

    2012-01-01

    Mining activity has been a significant driver of export growth as well as income and employment in parts of regional Australia. However, while income growth is an economic benefit, the high incomes associated with the mining sector may also lead to greater inequality. This paper describes an empirical analysis of mining activity and income inequality in regional Australia. The Gini coefficient (a measure of inequality) for personal income is found to be significantly associated with levels of...

  2. Image patch analysis of sunspots and active regions. I. Intrinsic dimension and correlation analysis

    Moon, Kevin R.; Li, Jimmy J.; Delouille, Véronique; De Visscher, Ruben; Watson, Fraser; Hero, Alfred O.

    2016-01-01

    Context. The flare productivity of an active region is observed to be related to its spatial complexity. Mount Wilson or McIntosh sunspot classifications measure such complexity but in a categorical way, and may therefore not use all the information present in the observations. Moreover, such categorical schemes hinder a systematic study of an active region's evolution for example. Aims: We propose fine-scale quantitative descriptors for an active region's complexity and relate them to the Mount Wilson classification. We analyze the local correlation structure within continuum and magnetogram data, as well as the cross-correlation between continuum and magnetogram data. Methods: We compute the intrinsic dimension, partial correlation, and canonical correlation analysis (CCA) of image patches of continuum and magnetogram active region images taken from the SOHO-MDI instrument. We use masks of sunspots derived from continuum as well as larger masks of magnetic active regions derived from magnetogram to analyze separately the core part of an active region from its surrounding part. Results: We find relationships between the complexity of an active region as measured by its Mount Wilson classification and the intrinsic dimension of its image patches. Partial correlation patterns exhibit approximately a third-order Markov structure. CCA reveals different patterns of correlation between continuum and magnetogram within the sunspots and in the region surrounding the sunspots. Conclusions: Intrinsic dimension has the potential to distinguish simple from complex active regions. These results also pave the way for patch-based dictionary learning with a view toward automatic clustering of active regions.

  3. Data-driven coronal evolutionary model of active region 11944.

    Kazachenko, M.

    2014-12-01

    Recent availability of systematic measurements of vector magnetic fields and Doppler velocities has allowed us to utilize a data-driven approach for modeling observed active regions (AR), a crucial step for understanding the nature of solar flare initiation. We use a sequence of vector magnetograms and Dopplergrams from the Helioseismic and Magnetic Imager (HMI) aboard the SDO to drive magnetofrictional (MF) model of the coronal magnetic field in the the vicinity of AR 11944, where an X1.2 flare on January 7 2014 occurred. To drive the coronal field we impose a time-dependent boundary condition based on temporal sequences of magnetic and electric fields at the bottom of the computational domain, i.e. the photosphere. To derive the electric fields we use a recently improved poloidal-toroidal decomposition (PTD), which we call the ``PTD-Doppler-FLCT-Ideal'' or PDFI technique. We investigate the results of the simulated coronal evolution, compare those with EUV observations from Atmospheric Imaging Assembly (AIA) and discuss what we could learn from them. This work is a a collaborative effort from the UC Berkeley Space Sciences Laboratory (SSL), Stanford University, and Lockheed-Martin and is a part of Coronal Global Evolutionary (CGEM) Model, funded jointly by NASA and NSF.

  4. Contracting and Erupting Components of Sigmoidal Active Regions

    Liu, Rui; Török, Tibor; Wang, Yuming; Wang, Haimin

    2012-01-01

    It is recently noted that solar eruptions can be associated with the contraction of coronal loops that are not involved in magnetic reconnection processes. In this paper, we investigate five coronal eruptions originating from four sigmoidal active regions, using high-cadence, high-resolution narrowband EUV images obtained by the Solar Dynamic Observatory (SDO}). The magnitudes of the flares associated with the eruptions range from the GOES-class B to X. Owing to the high-sensitivity and broad temperature coverage of the Atmospheric Imaging Assembly (AIA) onboard SDO, we are able to identify both the contracting and erupting components of the eruptions: the former is observed in cold AIA channels as the contracting coronal loops overlying the elbows of the sigmoid, and the latter is preferentially observed in warm/hot AIA channels as an expanding bubble originating from the center of the sigmoid. The initiation of eruption always precedes the contraction, and in the energetically mild events (B and C flares), ...

  5. Magnetic Nonpotentiality in Photospheric Active Regions as a Predictor of Solar Flares

    Yang, Xiao; Lin, GangHua; Zhang, Hongqi; Mao, Xinjie

    2013-01-01

    Based on several magnetic nonpotentiality parameters obtained from the vector photospheric active region magnetograms obtained with the Solar Magnetic Field Telescope at the Huairou Solar Observing Station over two solar cycles, a machine learning model has been constructed to predict the occurrence of flares in the corresponding active region within a certain time window. The Support Vector Classifier, a widely used general classifier, is applied to build and test the prediction models. Seve...

  6. Variability of trace gas concentrations over Asian region: satellite observations vs model

    Sheel, Varun; Richter, Andreas; Srivastava, Shuchita; Lal, Shyam

    2012-07-01

    Nitrogen dioxide (NO_2) and Carbon Monoxide (CO) play a key role in the chemistry of the tropospheric ozone and are emitted mainly by anthropogenic processes. These emissions have been increasing over Asia over the past few years due to rapid economic growth and yet there are very few systematic ground based observations of these species over this region. We have analysed ten years of data from space borne instruments: Global Ozone Monitoring Experiment (GOME), SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) and Measurements of Pollution in the Troposphere (MOPITT), which have been measuring the tropospheric abundance of these trace gases. We have examined trends over the period 1996-2008 in NO_2 and CO over a few Indian regions where high economic growth in the present decade is likely to see increased emissions for these species. However, even the highest growth rate of these species seen in the present study, is less when compared with similar polluted regions of China, where a much more rapid increase has been observed. In order to understand the trends and variability in atmospheric trace gas concentrations, one must take into account changes in emissions and transport. Only by assessing the relevance of each of these factors will it be possible to predict future changes with reasonable confidence. To this effect we have used a global chemical transport model, MOZART, to simulate concentrations of NO_2 and CO using the POET (European) and REAS (Asian) emission inventories. These are compared with satellite measurements to study seasonal variations and the discrepancies are discussed. The combined uncertainties of the emission inventory and retrieval of the satellite data could be contributing factors to the discrepancies. It may be thus worthwhile to develop emission inventories for India at a higher resolution to include local level activity data.

  7. Divergent Horizontal Sub-surface Flows within Active Region 11158

    Jain, Kiran; Hill, F

    2015-01-01

    We measure the horizontal subsurface flow in a fast emerging active region (NOAA 11158) using the ring-diagram technique and the HMI high-spatial resolution Dopplergrams. This active region had a complex magnetic structure and displayed significant changes in the morphology during its disk passage. Over the period of six days from 2011 February 11 to 16, the temporal variation in the magnitude of total velocity is found to follow the trend of magnetic field strength. We further analyze regions of individual magnetic polarity within AR 11158 and find that the horizontal velocity components in these sub-regions have significant variation with time and depth. The leading and trailing polarity regions move faster than the mixed-polarity region. Further, both zonal and meridional components have opposite signs for trailing and leading polarity regions at all depths showing divergent flows within the active region. We also find a sharp decrease in the magnitude of total horizontal velocity in deeper layer around ma...

  8. Simultaneous observations of ESF irregularities over Indian region using radar and GPS

    S. Sripathi

    2008-10-01

    Full Text Available In this paper, we present simultaneous observations of temporal and spatial variability of total electron content (TEC and GPS amplitude scintillations on L1 frequency (1.575 GHz during the time of equatorial spread F (ESF while the MST radar (53 MHz located at Gadanki (13.5° N, 79.2° E, Dip latitude 6.3° N, a low latitude station, made simultaneous observations. In particular, the latitudinal and longitudinal extent of TEC and L-band scintillations was studied in the Indian region for different types of ESF structures observed using the MST radar during the low solar activity period of 2004 and 2005. Simultaneous radar and GPS observations during severe ESF events in the pre-midnight hour reveal that significant GPS L band scintillations, depletions in TEC, and the double derivative of the TEC index (DROTI, which is a measure of fluctuations in TEC, obtained at low latitudes coincide with the appearance of radar echoes at Gadanki. As expected, when the irregularities reach higher altitudes as seen in the radar map during pre-midnight periods, strong scintillations on an L-band signal are observed at higher latitudes. Conversely, when radar echoes are confined to only lower altitudes, weak scintillations are found and their latitudinal extent is small. During magnetically quiet periods, we have recorded plume type radar echoes during a post-midnight period that is devoid of L-band scintillations. Using spectral slopes and cross-correlation index of the VHF scintillation observations, we suggest that these irregularities could be "dead" or "fossil" bubbles which are just drifting in from west. This scenario is consistent with the observations where suppression of pre-reversal enhancement (PRE in the eastward electric field is indicated by ionosonde observations of the height of equatorial F layer and also occurrence of low spectral width in the radar observations relative to pre-midnight period. However, absence of L-band scintillations during

  9. Universities and Economic Development Activities: A UK Regional Comparison

    Decter, Moira; Cave, Frank; Rose, Mary; Peers, Gill; Fogg, Helen; Smith, Susan M.

    2011-01-01

    A number of UK universities prioritize economic development or regeneration activities and for some of these universities such activities are the main focus of their knowledge transfer work. This study compares two regions of the UK--the North West and the South East of England--which have very different levels of economic performance.…

  10. Observations and modelling of inflation in the Lazufre volcanic region, South America

    Pearse, J.; Lundgren, P.

    2010-12-01

    The Central Volcanic Zone (CVZ) is an active volcanic arc in the central Andes, extending through Peru, southwestern Bolivia, Chile, and northwestern Argentina [De Silva, 1989; De Silva and Francis, 1991]. The CVZ includes a number of collapsed calderas, remnants of catastrophic eruptions, which are now thought to be inactive. However, recent Interferometric Synthetic Aperture Radar (InSAR) observations [Pritchard and Simons, 2004] show surface deformation occurring at some of these large ancient volcanic regions, indicating that magma chambers are slowly inflating beneath the surface. The mechanisms responsible for the initiation and growth of large midcrustal magma chambers remains poorly understood, and InSAR provides an opportunity for us to observe volcanic systems in remote regions that are otherwise difficult to monitor and observe. The Lastarria-Cordon del Azufre ("Lazufre" [Pritchard and Simons, 2002]) volcanic area is one such complex showing recent deformation, with average surface uplift rates of approximately 2.5 cm/year [Froger et al., 2007; Ruch et al, 2008]. We have processed InSAR data from ERS-1/2 and Envisat in the Lazufre volcanic area, including both ascending and descending satellite tracks. Time series analysis of the data shows steady uplift beginning in about 2000, continuing into 2010. We use boundary-element elastic models to invert for the depth and shape of the magmatic source responsible for the surface deformation. Given data from both ascending and descending tracks, we are able to resolve the ambiguity between the source depth and size, and constrain the geometry of the inflating magma source. Finite element modelling allows us to understand the effect of viscoelasticity on the development of the magma chamber.

  11. Observations of the Ionized, Neutral, and Molecular Components Associated with an Expanding H II Region

    Lebrón, Mayra E.; Rodríguez, Luis F.; Lizano, Susana

    2001-10-01

    We present H92α, HI 21 cm, NH3 (1, 1) and NH3 (2, 2) lines and radio continuum observations toward the compact HII region G111.61+0.37, located in the region Sharpless 159. The dense molecular gas (traced by the ammonia lines) in the vicinity of G111.61+0.37 is distributed in clumps indicating considerable inhomogeneity in the molecular gas. A warm (Trot=47 K) ammonia clump is located just in front of the head of the cometary HII region. The photodissociated region associated to this compact HII region was detected in the HI 21 cm line. The neutral region is extended in the direction opposite to the dense molecular gas. The velocity distribution of the neutral gas suggests that the HI region is expanding in a champagne flow resembling that of the HII region, although with much lower velocities.

  12. MAG4 Versus Alternative Techniques for Forecasting Active-Region Flare Productivity

    Falconer, David A.; Moore, Ronald L.; Barghouty, Abdulnasser F.; Khazanov, Igor

    2014-01-01

    MAG4 is a technique of forecasting an active region's rate of production of major flares in the coming few days from a free-magnetic-energy proxy. We present a statistical method of measuring the difference in performance between MAG4 and comparable alternative techniques that forecast an active region's major-flare productivity from alternative observed aspects of the active region. We demonstrate the method by measuring the difference in performance between the "Present MAG4" technique and each of three alternative techniques, called "McIntosh Active-Region Class," "Total Magnetic Flux," and "Next MAG4." We do this by using (1) the MAG4 database of magnetograms and major-flare histories of sunspot active regions, (2) the NOAA table of the major-flare productivity of each of 60 McIntosh active-region classes of sunspot active regions, and (3) five technique-performance metrics (Heidke Skill Score, True Skill Score, Percent Correct, Probability of Detection, and False Alarm Rate) evaluated from 2000 random two-by-two contingency tables obtained from the databases. We find that (1) Present MAG4 far outperforms both McIntosh Active-Region Class and Total Magnetic Flux, (2) Next MAG4 significantly outperforms Present MAG4, (3) the performance of Next MAG4 is insensitive to the forward and backward temporal windows used, in the range of one to a few days, and (4) forecasting from the free-energy proxy in combination with either any broad category of McIntosh active-region classes or any Mount Wilson active-region class gives no significant performance improvement over forecasting from the free-energy proxy alone (Present MAG4).

  13. Analysis of visibility simulation of three polar regions from lunar-based earth observation

    Ye, Hanlin; Liu, Guang; Ren, Yuanzhen; Guo, Huadong; Ding, Yixing

    2016-07-01

    Global environment change has caught the attention of many scientists around the world. The Arctic, Antarctic and Tibet Plateau are known as the three polar regions. They are the world's largest storage of cold and carbon which are the sensitive regions of global environment change. These three regions have significant impacts on the global environment change. It is extremely obvious that the environment change of these three regions is one of the major factors of global environment change. The special geographical positions of these three regions have great influence on the local climate and ecological environment that caused the climate is very bad and few people can get there, so there is very little observation data exists. In addition, these three regions have large scale and long-term observation characteristics. Since the meaning of remote sensing technology came out, we have developed airborne and space-borne Earth observation system. However, when taking three polar regions for researching, we will have to face the problems of temporal coherence and spatial continuity in the global scale, which challenges the Earth observation on the satellite and airborne platform. Moon is the unique natural satellite of the Earth, which always has one side facing it, with the advantages of large coverage, long-life platform, stable geological structure and multi-spheres three-dimensional detecting, turning out to be the ideal platform for observing three polar regions. At present and in the near future, the study of Earth observation data from a lunar observatory would be difficult to carry out, so a simulation is used in this paper to analyze the visibility of three polar regions. At first, we discuss the motion pattern of the Sun-Earth-Moon system. Then we construct a simulation system with simulated optical sensors setting up at different places on the Moon, finding that sunlight has great influence on optical observation. The visible region of a lunar-based optical

  14. 30 MHz radar observations of artificial E region field-aligned plasma irregularities

    D. L. Hysell

    2008-01-01

    Artificial E region field aligned irregularities (FAIs) have been observed during heating experiments at the HAARP facility using a new 30 MHz coherent scatter radar imager deployed near Homer, Alaska. Irregularities were observed during brief experiments on three quiet days in July and August, 2007, when the daytime E region critical frequency was close to 3 MHz. Irregularities were consistently generated and detected during experiments with O-mode HF pumping on zenith with a 1-min on, 1-min...

  15. Evaluation of Observation-Fused Regional Air Quality Model Results for Population Air Pollution Exposure Estimation

    Chen, Gang; Li, Jingyi; Ying, Qi; Sherman, Seth; Perkins, Neil; Rajeshwari, Sundaram; Mendola, Pauline

    2014-01-01

    In this study, Community Multiscale Air Quality (CMAQ) model was applied to predict ambient gaseous and particulate concentrations during 2001 to 2010 in 15 hospital referral regions (HRRs) using a 36-km horizontal resolution domain. An inverse distance weighting based method was applied to produce exposure estimates based on observation-fused regional pollutant concentration fields using the differences between observations and predictions at grid cells where air quality monitors were locate...

  16. Observed and simulated precipitation responses in wet and dry regions 1850–2100

    Global warming is expected to enhance fluxes of fresh water between the surface and atmosphere, causing wet regions to become wetter and dry regions drier, with serious implications for water resource management. Defining the wet and dry regions as the upper 30% and lower 70% of the precipitation totals across the tropics (30° S–30° N) each month we combine observations and climate model simulations to understand changes in the wet and dry regions over the period 1850–2100. Observed decreases in precipitation over dry tropical land (1950–2010) are also simulated by coupled atmosphere–ocean climate models (−0.3%/decade) with trends projected to continue into the 21st century. Discrepancies between observations and simulations over wet land regions since 1950 exist, relating to decadal fluctuations in El Niño southern oscillation, the timing of which is not represented by the coupled simulations. When atmosphere-only simulations are instead driven by observed sea surface temperature they are able to adequately represent this variability over land. Global distributions of precipitation trends are dominated by spatial changes in atmospheric circulation. However, the tendency for already wet regions to become wetter (precipitation increases with warming by 3% K−1 over wet tropical oceans) and the driest regions drier (precipitation decreases of −2% K−1 over dry tropical land regions) emerges over the 21st century in response to the substantial surface warming. (letter)

  17. Regional Economic Activity in Turkey: A New Economic Geography Approach

    Turgut, Mehmet Burak

    2014-01-01

    This paper studies the spatial economic activity in Turkey and estimates the correlation between wages and consumer demand across NUTS1 regions of Turkey. First, I estimate simple market potential function to test whether closeness to larger markets has impact on wages. Second, I estimate Krugman (1993) economic geography model to see the agglomeration forces in Turkey. The results suggest that wages are higher in the regions close to larger markets and low trade costs and high share of expen...

  18. The origin of net electric currents in solar active regions

    Dalmasse, K; Démoulin, P; Kliem, B; Török, T; Pariat, E

    2015-01-01

    There is a recurring question in solar physics about whether or not electric currents are neutralized in active regions (ARs). This question was recently revisited using three-dimensional (3D) magnetohydrodynamic (MHD) numerical simulations of magnetic flux emergence into the solar atmosphere. Such simulations showed that flux emergence can generate a substantial net current in ARs. Another source of AR currents are photospheric horizontal flows. Our aim is to determine the conditions for the occurrence of net vs. neutralized currents with this second mechanism. Using 3D MHD simulations, we systematically impose line-tied, quasi-static, photospheric twisting and shearing motions to a bipolar potential magnetic field. We find that such flows: (1) produce both {\\it direct} and {\\it return} currents, (2) induce very weak compression currents - not observed in 2.5D - in the ambient field present in the close vicinity of the current-carrying field, and (3) can generate force-free magnetic fields with a net current...

  19. Evidence of Twisted flux-tube Emergence in Active Regions

    Poisson, Mariano; Démoulin, Pascal; Fuentes, Marcelo López

    2015-01-01

    Elongated magnetic polarities are observed during the emergence phase of bipolar active regions (ARs). These extended features, called magnetic tongues, are interpreted as a consequence of the azimuthal component of the magnetic flux in the toroidal flux-tubes that form ARs. We develop a new systematic and user-independent method to identify AR tongues. Our method is based on determining and analyzing the evolution of the AR main polarity inversion line (PIL). The effect of the tongues is quantified by measuring the acute angle [ tau] between the orientation of the PIL and the direction orthogonal to the AR main bipolar axis. We apply a simple model to simulate the emergence of a bipolar AR. This model lets us interpret the effect of magnetic tongues on parameters that characterize ARs ( e.g. the PIL inclination and the tilt angles, and their evolution). In this idealized kinematic emergence model, tau is a monotonically increasing function of the twist and has the same sign as the magnetic helicity. We syste...

  20. Magnetic helicity and energy spectra of a solar active region

    Zhang, Hongqi; Sokoloff, D D

    2013-01-01

    We compute magnetic helicity and energy spectra of the solar active region NOAA 11158 during 11-15 February 2011 at 20 degr southern heliographic latitude using observational photospheric vector magnetograms. We adopt the isotropic representation of the Fourier-transformed two-point correlation tensor of the magnetic field. The sign of magnetic helicity turns out to be predominantly positive at all wavenumbers. This sign is consistent with what is theoretically expected for the southern hemisphere. The relative magnetic helicity is around 8% and strongest at intermediate wavenumbers of k ~ 0.4 Mm^{-1}, corresponding to a scale of 2 pi/k ~ 16 Mm. The same sign and a somewhat smaller value is also found for the relative current helicity evaluated in real space based on the vertical components of magnetic field and current density. The current helicity spectrum is estimated from the magnetic helicity spectrum and its modulus shows a k^{-5/3} spectrum at large wavenumbers. A similar power law is also obtained for...

  1. A Regional CO2 Observing System Simulation Experiment for the ASCENDS Satellite Mission

    Wang, J. S.; Kawa, S. R.; Eluszkiewicz, J.; Baker, D. F.; Mountain, M.; Henderson, J.; Nehrkorn, T.; Zaccheo, T. S.

    2014-01-01

    Top-down estimates of the spatiotemporal variations in emissions and uptake of CO2 will benefit from the increasing measurement density brought by recent and future additions to the suite of in situ and remote CO2 measurement platforms. In particular, the planned NASA Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) satellite mission will provide greater coverage in cloudy regions, at high latitudes, and at night than passive satellite systems, as well as high precision and accuracy. In a novel approach to quantifying the ability of satellite column measurements to constrain CO2 fluxes, we use a portable library of footprints (surface influence functions) generated by the WRF-STILT Lagrangian transport model in a regional Bayesian synthesis inversion. The regional Lagrangian framework is well suited to make use of ASCENDS observations to constrain fluxes at high resolution, in this case at 1 degree latitude x 1 degree longitude and weekly for North America. We consider random measurement errors only, modeled as a function of mission and instrument design specifications along with realistic atmospheric and surface conditions. We find that the ASCENDS observations could potentially reduce flux uncertainties substantially at biome and finer scales. At the 1 degree x 1 degree, weekly scale, the largest uncertainty reductions, on the order of 50 percent, occur where and when there is good coverage by observations with low measurement errors and the a priori uncertainties are large. Uncertainty reductions are smaller for a 1.57 micron candidate wavelength than for a 2.05 micron wavelength, and are smaller for the higher of the two measurement error levels that we consider (1.0 ppm vs. 0.5 ppm clear-sky error at Railroad Valley, Nevada). Uncertainty reductions at the annual, biome scale range from 40 percent to 75 percent across our four instrument design cases, and from 65 percent to 85 percent for the continent as a whole. Our uncertainty

  2. A regional CO2 observing system simulation experiment for the ASCENDS Satellite Mission

    J. S. Wang

    2014-05-01

    Full Text Available Top-down estimates of the spatiotemporal variations in emissions and uptake of CO2 will benefit from the increasing measurement density brought by recent and future additions to the suite of in situ and remote CO2 measurement platforms. In particular, the planned NASA Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS satellite mission will provide greater coverage in cloudy regions, at high latitudes, and at night than passive satellite systems, as well as high precision and accuracy. In a novel approach to quantifying the ability of satellite column measurements to constrain CO2 fluxes, we use a portable library of footprints (surface influence functions generated by the WRF-STILT Lagrangian transport model in a regional Bayesian synthesis inversion. The regional Lagrangian framework is well suited to make use of ASCENDS observations to constrain fluxes at high resolution, in this case at 1° latitude × 1° longitude and weekly for North America. We consider random measurement errors only, modeled as a function of mission and instrument design specifications along with realistic atmospheric and surface conditions. We find that the ASCENDS observations could potentially reduce flux uncertainties substantially at biome and finer scales. At the 1° × 1°, weekly scale, the largest uncertainty reductions, on the order of 50%, occur where and when there is good coverage by observations with low measurement errors and the a priori uncertainties are large. Uncertainty reductions are smaller for a 1.57 μm candidate wavelength than for a 2.05 μm wavelength, and are smaller for the higher of the two measurement error levels that we consider (1.0 ppm vs. 0.5 ppm clear-sky error at Railroad Valley, Nevada. Uncertainty reductions at the annual, biome scale range from ∼40% to ∼75% across our four instrument design cases, and from ∼65% to ∼85% for the continent as a whole. Our uncertainty reductions at various scales are

  3. A regional CO2 observing system simulation experiment for the ASCENDS Satellite Mission

    Wang, J. S.; Kawa, S. R.; Eluszkiewicz, J.; Baker, D. F.; Mountain, M.; Henderson, J.; Nehrkorn, T.; Zaccheo, T. S.

    2014-05-01

    Top-down estimates of the spatiotemporal variations in emissions and uptake of CO2 will benefit from the increasing measurement density brought by recent and future additions to the suite of in situ and remote CO2 measurement platforms. In particular, the planned NASA Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) satellite mission will provide greater coverage in cloudy regions, at high latitudes, and at night than passive satellite systems, as well as high precision and accuracy. In a novel approach to quantifying the ability of satellite column measurements to constrain CO2 fluxes, we use a portable library of footprints (surface influence functions) generated by the WRF-STILT Lagrangian transport model in a regional Bayesian synthesis inversion. The regional Lagrangian framework is well suited to make use of ASCENDS observations to constrain fluxes at high resolution, in this case at 1° latitude × 1° longitude and weekly for North America. We consider random measurement errors only, modeled as a function of mission and instrument design specifications along with realistic atmospheric and surface conditions. We find that the ASCENDS observations could potentially reduce flux uncertainties substantially at biome and finer scales. At the 1° × 1°, weekly scale, the largest uncertainty reductions, on the order of 50%, occur where and when there is good coverage by observations with low measurement errors and the a priori uncertainties are large. Uncertainty reductions are smaller for a 1.57 μm candidate wavelength than for a 2.05 μm wavelength, and are smaller for the higher of the two measurement error levels that we consider (1.0 ppm vs. 0.5 ppm clear-sky error at Railroad Valley, Nevada). Uncertainty reductions at the annual, biome scale range from ∼40% to ∼75% across our four instrument design cases, and from ∼65% to ∼85% for the continent as a whole. Our uncertainty reductions at various scales are substantially smaller

  4. Characteristics of high frequency gravity waves observed in OH nightglow from low latitude Indian region during January and February 2007

    Complete text of publication follows. The role of short scale high frequency gravity waves in the upper mesosphere lower thermosphere (UMLT) region is now well appreciated. Still their global distribution and source regions are not well known. All-sky imaging of nightglow emissions provide a unique way to study the high frequency waves in the UMLT region. In this work we have studied the characteristics of the waves observed in OH Meinel band emissions over Tirunelveli (8.7degN, 77.8degE) during January and February months of 2007. We have concentrated on the OH band observations because they have better SNR than other emissions and also wave activity is more in OH than other nightglow. From Indian sector, this is the first statistical study of short period waves with nightglow imaging. Our study shows the predominance of meridionally propagating waves indicating wind filtering effects in the lower atmospheric region. Such predominant meridional propagation during solstice periods is also seen from few other sites. Apart from that considerable number of waves propagated towards northwest direction. This may be an indication for existence of strong source region situated to the southeast of the observation site. It should be noted that the strong convective activity over and around Indonesian region is situated southeast to Tirunelveli. The average wavelength and apparent phase velocity of the observed waves are 17.7 km and 52.0 m/s respectively. These parameters are obtained from observations made during winter period only. A wider picture will be available once the characterization is over for a wider dataset covering other seasons also.

  5. The Transition Region Response to a Coronal Nanoflare: Forward Modeling and Observations in SDO/AIA

    Viall-Kepko, Nicholeen M.; Klimchuk, James A.

    2015-01-01

    The corona and transition region (TR) are fundamentally coupled through the processes of thermal conduction and mass exchange. It is not possible to understand one without the other. Yet the temperature-dependent emissions from the two locations behave quite differently in the aftermath of an impulsive heating event such as a coronal nanoflare. Whereas the corona cools sequentially, emitting first at higher temperatures and then at lower temperatures, the TR is multithermal and the emission at all temperatures responds in unison. We have previously applied the automated time lag technique of Viall & Klimchuk to disk observations of an active region (AR) made by the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory. Lines of sight passing through coronal plasma show clear evidence for post-nanoflare cooling, while lines of sight intersecting the TR footpoints of coronal strands show zero time lag. In this paper, we use the EBTEL hydrodynamics code to demonstrate that this is precisely the expected behavior when the corona is heated by nanoflares. We also apply the time lag technique for the first time to off-limb observations of an AR. Since TR emission is not present above the limb, the occurrence of zero time lags is greatly diminished, supporting the conclusion that zero time lags measured on the disk are due to TR plasma. Lastly, we show that the "coronal" channels in AIA can be dominated by bright TR emission. When defined in a physically meaningful way, the TR reaches a temperature of roughly 60% the peak temperature in a flux tube. The TR resulting from impulsive heating can extend to 3 MK and higher, well within the range of the "coronal" AIA channels.

  6. THE TRANSITION REGION RESPONSE TO A CORONAL NANOFLARE: FORWARD MODELING AND OBSERVATIONS IN SDO/AIA

    Viall, Nicholeen M.; Klimchuk, James A. [NASA Goddard Space Flight Center, Solar Physics Laboratory, Greenbelt, MD 20771 (United States)

    2015-01-20

    The corona and transition region (TR) are fundamentally coupled through the processes of thermal conduction and mass exchange. It is not possible to understand one without the other. Yet the temperature-dependent emissions from the two locations behave quite differently in the aftermath of an impulsive heating event such as a coronal nanoflare. Whereas the corona cools sequentially, emitting first at higher temperatures and then at lower temperatures, the TR is multithermal and the emission at all temperatures responds in unison. We have previously applied the automated time lag technique of Viall and Klimchuk to disk observations of an active region (AR) made by the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory. Lines of sight passing through coronal plasma show clear evidence for post-nanoflare cooling, while lines of sight intersecting the TR footpoints of coronal strands show zero time lag. In this paper, we use the EBTEL hydrodynamics code to demonstrate that this is precisely the expected behavior when the corona is heated by nanoflares. We also apply the time lag technique for the first time to off-limb observations of an AR. Since TR emission is not present above the limb, the occurrence of zero time lags is greatly diminished, supporting the conclusion that zero time lags measured on the disk are due to TR plasma. Lastly, we show that the ''coronal'' channels in AIA can be dominated by bright TR emission. When defined in a physically meaningful way, the TR reaches a temperature of roughly 60% the peak temperature in a flux tube. The TR resulting from impulsive heating can extend to 3 MK and higher, well within the range of the ''coronal'' AIA channels.

  7. Identifying the Main Driver of Active Region Outflows

    Baker, D.; van Driel-Gesztelyi, L.; Mandrini, C. H.; Démoulin, P.; Murray, M. J.

    2012-08-01

    Hinode's EUV Imaging Spectrometer (EIS) has discovered ubiquitous outflows of a few to 50 km s-1 from active regions (ARs). The characteristics of these outflows are very curious in that they are most prominent at the AR boundary and appear over monopolar magnetic areas. They are linked to strong non-thermal line broadening and are stronger in hotter EUV lines. The outflows persist for at least several days. Whereas red-shifted down flows observed in AR closed loops are well understood, to date there is no general consensus for the mechanism(s) driving blue-shifted AR-related outflows. We use Hinode EIS and X-Ray Telescope observations of AR 10942 coupled with magnetic modeling to demonstrate for the first time that the outflows originate from specific locations of the magnetic topology where field lines display strong gradients of magnetic connectivity, namely quasi-separatrix layers (QSLs), or in the limit of infinitely thin QSLs, separatrices. The strongest AR outflows were found to be in the vicinity of QSL sections located over areas of strong magnetic field. We argue that magnetic reconnection at QSLs, separating closed field lines of the AR and either large-scale externally connected or ‘open’ field lines, is a viable mechanism for driving AR outflows which are potentially sources of the slow solar wind. In fact, magnetic reconnection along QSLs (including separatricies) is the first theory to explain the most puzzling characteristics of the outflows, namely their occurrence over monopolar areas at the periphery of ARs and their longevity.

  8. Costa Rica Variable Star Observation Program: Continuation of the research started in the Second Astronomical Observation Regional Campaign TAD/IAU Tegucigalpa Honduras, 1998.

    Araya Rodriguez, E.

    1998-11-01

    In the last months of January and February, it was the Second Astronomical Observation Regional Campaign TAD/IAU in the Suyapa Astronomical Observatory, Tegucigalpa, Honduras; sponsored by the International Astronomical Union, Honduras Government and the Universidad Nacional Autonoma de Honduras. In that opportunity, during the campaign, it began a variable star observation program, according to international regulation of the American Association of Variable Stars Observers (AAVSO). The activities were about the use of general experimental techniques that allow people to do studies naked eye, with telescopes or photometers depending on the observed star magnitude. The continuation in Costa Rica of that research added to some gotten results will be presented in this work.

  9. STEREO observations of the energetic ions in tilted corotating interaction regions

    Bucik, R; Korth, A; Mason, G M; 10.1029/2010JA016311

    2013-01-01

    In this paper we examine suprathermal He ions measured by the SIT (Suprathermal Ion Telescope) instrument associated with tilted corotating interaction regions (CIRs). We use observations of the two STEREO spacecraft (s/c) for the first 2.7 years of the mission, along with ground-based measurements of the solar magnetic field during the unusually long minimum of Solar Cycle 23. Due to the unique configuration of the STEREO s/c orbits we are able to investigate spatial variations in the intensity of the corotating ions on time scales of less than one solar rotation. The observations reveal that the occurrence of the strong CIR events was the most frequent at the beginning of the period. The inclination of the heliospheric current sheet relative to the heliographic equator (the tilt angle) was quite high in the first stage of the mission and gradually flattened with the time, followed by a decrease in the CIR activity. By examining the differences between measurements on the two STEREO s/c we discuss how the ch...

  10. FIP Bias Evolution in a Decaying Active Region

    Baker, D.; Brooks, D. H.; Démoulin, P.; Yardley, S. L.; van Driel-Gesztelyi, L.; Long, D. M.; Green, L. M.

    2015-04-01

    Solar coronal plasma composition is typically characterized by first ionization potential (FIP) bias. Using spectra obtained by Hinode’s EUV Imaging Spectrometer instrument, we present a series of large-scale, spatially resolved composition maps of active region (AR)11389. The composition maps show how FIP bias evolves within the decaying AR during the period 2012 January 4-6. Globally, FIP bias decreases throughout the AR. We analyzed areas of significant plasma composition changes within the decaying AR and found that small-scale evolution in the photospheric magnetic field is closely linked to the FIP bias evolution observed in the corona. During the AR’s decay phase, small bipoles emerging within supergranular cells reconnect with the pre-existing AR field, creating a pathway along which photospheric and coronal plasmas can mix. The mixing timescales are shorter than those of plasma enrichment processes. Eruptive activity also results in shifting the FIP bias closer to photospheric in the affected areas. Finally, the FIP bias still remains dominantly coronal only in a part of the AR’s high-flux density core. We conclude that in the decay phase of an AR’s lifetime, the FIP bias is becoming increasingly modulated by episodes of small-scale flux emergence, i.e., decreasing the AR’s overall FIP bias. Our results show that magnetic field evolution plays an important role in compositional changes during AR development, revealing a more complex relationship than expected from previous well-known Skylab results showing that FIP bias increases almost linearly with age in young ARs.

  11. Regional cerebral blood flow in psychiatry: The resting and activated brains of schizophrenic patients

    The investigation of regional brain functioning in schizophrenia has been based on behavioral techniques. Although results are sometimes inconsistent, the behavioral observations suggest left hemispheric dysfunction and left hemispheric overreaction. Recent developments in neuroimaging technology make possible major refinements in assessing regional brain function. Both anatomical and physiological information now be used to study regional brain development in psychiatric disorders. This chapter describes the application of one method - the xenon-133 technique for measuring regional cerebral blood flow (rCBF) - in studying the resting and activated brains of schizoprenic patients

  12. Large-scale traveling ionospheric disturbances observed using GPS receivers over high-latitude and equatorial regions

    Idrus, Intan Izafina; Abdullah, Mardina; Hasbi, Alina Marie; Husin, Asnawi; Yatim, Baharuddin

    2013-09-01

    This paper presents the first results of large-scale traveling ionospheric disturbances (LSTIDs) observation during two moderate magnetic storm events on 28 May 2011 (SYM-H∼ -94 nT and Dst∼-80 nT) and 6 August 2011 (SYM-H∼-126 nT and Dst∼-113 nT) over the high-latitude region in Russia, Sweden, Norway, Iceland and Greenland and equatorial region in the Peninsular Malaysia using vertical total electron content (VTEC) from the Global Positioning System (GPS) observations measurement. The propagation of the LSTID signatures in the GPS TEC measurements over Peninsular Malaysia was also investigated using VTEC map. The LSTIDs were found to propagate both equatorward and poleward directions during these two events. The results showed that the LSTIDs propagated faster at high-latitude region with an average phase velocity of 1074.91 m/s than Peninsular Malaysia with an average phase velocity of 604.84 m/s. The LSTIDs at the high-latitude region have average periods of 150 min whereas the ones observed over Peninsular Malaysia have average periods of 115 min. The occurrences of these LSTIDs were also found to be the subsequent effects of substorm activities in the auroral region. To our knowledge, this is the first result of observation of LSTIDs over Peninsular Malaysia during the 24th solar cycle.

  13. 12 Years of Stellar Activity Observations in Argentina

    Mauas, Pablo J D; Diaz, R; Vieytes, M; Petrucci, R; Jofre, E; Abrevaya, X; Luoni, M L; Valenzuela, P

    2012-01-01

    We present an observational program we started in 1999, to systematically obtain mid-resolution spectra of late-type stars, to study in particular chromospheric activity. In particular, we found cyclic activity in four dM stars, including Prox-Cen. We directly derived the conversion factor that translates the known S index to flux in the Ca II cores, and extend its calibration to a wider spectral range. We investigated the relation between the activity measurements in the calcium and hydrogen lines, and found that the usual correlation observed is the product of the dependence of each flux on stellar color, and it is not always preserved when simultaneous observations of a particular star are considered. We also used our observations to model the chromospheres of stars of different spectral types and activity levels, and found that the integrated chromospheric radiative losses, normalized to the surface luminosity, show a unique trend for G and K dwarfs when plotted against the S index.

  14. New inferences from spectral seismic energy measurement of a link between regional seismicity and volcanic activity at Mt. Etna, Italy

    Ortiz, R.; CSIC, Madrid; Falsaperla, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Marrero, J.M.; Departamento de Geologia. Universidad de La Laguna, Tenerife, Spain; Messina, A.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia

    2009-01-01

    The existence of a relationship between regional seismicity and changes in volcanic activity has been the subject of several studies in the last years. Generally, activity in basaltic volcanoes such as Villarica (Chile) and Tungurahua (Ecuador) shows very little changes after the occurrence of regional earthquakes. In a few cases volcanic activity has changed before the occurrence of regional earthquakes, such as observed at Teide, Tenerife, in 2004 and 2005 (Tárraga et al., 2006)...

  15. Socioeconomic and regional differences in active transportation in Brazil

    de Sá, Thiago Hérick; Pereira, Rafael Henrique Moraes; Duran, Ana Clara; Monteiro, Carlos Augusto

    2016-01-01

    ABSTRACT OBJECTIVE To present national estimates regarding walking or cycling for commuting in Brazil and in 10 metropolitan regions. METHODS By using data from the Health section of 2008’s Pesquisa Nacional por Amostra de Domicílio (Brazil’s National Household Sample Survey), we estimated how often employed people walk or cycle to work, disaggregating our results by sex, age range, education level, household monthly income per capita, urban or rural address, metropolitan regions, and macro-regions in Brazil. Furthermore, we estimated the distribution of this same frequency according to quintiles of household monthly income per capita in each metropolitan region of the country. RESULTS A third of the employed men and women walk or cycle from home to work in Brazil. For both sexes, this share decreases as income and education levels rise, and it is higher among younger individuals, especially among those living in rural areas and in the Northeast region of the country. Depending on the metropolitan region, the practice of active transportation is two to five times more frequent among low-income individuals than among high-income individuals. CONCLUSIONS Walking or cycling to work in Brazil is most frequent among low-income individuals and the ones living in less economically developed areas. Active transportation evaluation in Brazil provides important information for public health and urban mobility policy-making PMID:27355465

  16. LOCAL DEVELOPMENT IN NORTHEST REGION THROUGH ACTIVITIES IN ITC DOMAIN

    Daniela\tENACHESCU

    2015-06-01

    Full Text Available Economic areas with high technology are key drivers in sustainable regional development, including unemployment and consequently decreasing population migration in the region. Northeast Region is the largest development region of Romania in terms of number of inhabitants and the owned area. On 01/01/2014, according to balance employment, labor resources of the region were numbered 2,428,700, which represent 49.6% of employed population. The registered unemployment rate at 31 August 2014 was 6.5%, with 82 thousand unemployed registered. In terms of participation in the main economic activities, civilian employment in agriculture, forestry and fishing is predominant (40.1% while in service, civilian employment is 37.1%, while industry and construction is 22.8%. The paper aims to analyze the situation that the potential employment and development opportunities for the Northeast region through activities in the field of ITC domain. Unfortunately, this area was the worst in most indicators, the use of computers and the internet to the turnover of companies and investments in the IT & C and unfortunately in terms of employment population that is under 50%

  17. Observational evidence for enhanced magnetic activity of superflare stars.

    Karoff, Christoffer; Knudsen, Mads Faurschou; De Cat, Peter; Bonanno, Alfio; Fogtmann-Schulz, Alexandra; Fu, Jianning; Frasca, Antonio; Inceoglu, Fadil; Olsen, Jesper; Zhang, Yong; Hou, Yonghui; Wang, Yuefei; Shi, Jianrong; Zhang, Wei

    2016-01-01

    Superflares are large explosive events on stellar surfaces one to six orders-of-magnitude larger than the largest flares observed on the Sun throughout the space age. Due to the huge amount of energy released in these superflares, it has been speculated if the underlying mechanism is the same as for solar flares, which are caused by magnetic reconnection in the solar corona. Here, we analyse observations made with the LAMOST telescope of 5,648 solar-like stars, including 48 superflare stars. These observations show that superflare stars are generally characterized by larger chromospheric emissions than other stars, including the Sun. However, superflare stars with activity levels lower than, or comparable to, the Sun do exist, suggesting that solar flares and superflares most likely share the same origin. The very large ensemble of solar-like stars included in this study enables detailed and robust estimates of the relation between chromospheric activity and the occurrence of superflares. PMID:27009381

  18. Active Ageing Level of Older Persons: Regional Comparison in Thailand

    Haque, Md. Nuruzzaman

    2016-01-01

    Active ageing level and its discrepancy in different regions (Bangkok, Central, North, Northeast, and South) of Thailand have been examined for prioritizing the policy agenda to be implemented. Attempt has been made to test preliminary active ageing models for Thai older persons and hence active ageing index (AAI, ranges from 0 to 1) has been estimated. Using nationally representative data and confirmatory factor analysis approach, this study justified active ageing models for female and male older persons in Thailand. Results revealed that active ageing level of Thai older persons is not high (mean AAIs for female and male older persons are 0.64 and 0.61, resp., and those are significantly different (p health and economic security, to promote participation in social groups and longer working lives, and to arrange learning programs, would be helpful for increasing older persons' active ageing level in Thailand.

  19. Active listening in medical consultations: development of the Active Listening Observation Scale (ALOS-global).

    Fassaert, T.; van Dulmen, S.; Schellevis, F.; BENSING, J

    2007-01-01

    OBJECTIVE: Active listening is a prerequisite for a successful healthcare encounter, bearing potential therapeutic value especially in clinical situations that require no specific medical intervention. Although generally acknowledged as such, active listening has not been studied in depth. This paper describes the development of the Active Listening Observation Scale (ALOS-global), an observation instrument measuring active listening and its validation in a sample of general practice consulta...

  20. Early life stress affects limited regional brain activity in depression.

    Du, Lian; Wang, Jingjie; Meng, Ben; Yong, Na; Yang, Xiangying; Huang, Qingling; Zhang, Yan; Yang, Lingling; Qu, Yuan; Chen, Zhu; Li, Yongmei; Lv, Fajin; Hu, Hua

    2016-01-01

    Early life stress (ELS) can alter brain function and increases the risk of major depressive disorder (MDD) in later life. This study investigated whether ELS contributes to differences in regional brain activity between MDD patients and healthy controls (HC), as measured by amplitude of low-frequency fluctuation (ALFF)/fractional (f)ALFF. Eighteen first-episode, treatment-naïve MDD patients and HC were assessed with the Childhood Trauma Questionnaire and resting-state functional magnetic resonance imaging. We compared ALFF/fALFF between MDD patients and HC, with or without controlling for ELS, and determined whether ELS level was correlated with regional brain activity in each group. After regressing out ELS, we found that ALFF increased in bilateral amygdala and left orbital/cerebellum, while fALFF decreased in left inferior temporal and right middle frontal gyri in MDD patients relative to controls. ELS positively correlated with regional activity in the left cerebellum in MDD and in the right post-central/inferior temporal/superior frontal cingulate, inferior frontal gyrus and bilateral cerebellum in HC. Our findings indicate that there is only very limited region showing correlation between ELS and brain activity in MDD, while diverse areas in HC, suggesting ELS has few impacts on MDD patients. PMID:27138376

  1. Early life stress affects limited regional brain activity in depression

    Du, Lian; Wang, Jingjie; Meng, Ben; Yong, Na; Yang, Xiangying; Huang, Qingling; Zhang, Yan; Yang, Lingling; Qu, Yuan; Chen, Zhu; Li, Yongmei; Lv, Fajin; Hu, Hua

    2016-01-01

    Early life stress (ELS) can alter brain function and increases the risk of major depressive disorder (MDD) in later life. This study investigated whether ELS contributes to differences in regional brain activity between MDD patients and healthy controls (HC), as measured by amplitude of low-frequency fluctuation (ALFF)/fractional (f)ALFF. Eighteen first-episode, treatment-naïve MDD patients and HC were assessed with the Childhood Trauma Questionnaire and resting-state functional magnetic resonance imaging. We compared ALFF/fALFF between MDD patients and HC, with or without controlling for ELS, and determined whether ELS level was correlated with regional brain activity in each group. After regressing out ELS, we found that ALFF increased in bilateral amygdala and left orbital/cerebellum, while fALFF decreased in left inferior temporal and right middle frontal gyri in MDD patients relative to controls. ELS positively correlated with regional activity in the left cerebellum in MDD and in the right post-central/inferior temporal/superior frontal cingulate, inferior frontal gyrus and bilateral cerebellum in HC. Our findings indicate that there is only very limited region showing correlation between ELS and brain activity in MDD, while diverse areas in HC, suggesting ELS has few impacts on MDD patients. PMID:27138376

  2. Dynamic Precursors of Flares in Active Region NOAA 10486

    Korsos, M B; Baranyi, T; Ludmany, A

    2015-01-01

    Four different methods are applied here to study the precursors of flare activity in the Active Region NOAA 10486. Two approaches track the temporal behaviour of suitably chosen features (one, the weighted horizontal gradient WGM, is generalised form the horizontal gradient of the magnetic field, GM; another is the sum of the horizontal gradient of the magnetic field, GS, for all sunspot pairs). WGM is a photospheric indicator that is a proxy measure of magnetic non-potentiality of a specific area of the active region, i.e. it captures the temporal variation of the weighted horizontal gradient of magnetic flux summed up for the region where opposite magnetic polarities are highly mixed. The third one, referred to as the separateness parameter, S(lf), considers the overall morphology. Further, GS and S(lf) are photospheric newly defined quick-look indicators of the polarity mix of the entire active region. The fourth method is tracking the temporal variation of small x-ray flares, their times of succession and...

  3. Unwinding motion of a twisted active-region filament

    Yan, X L; Liu, J H; Kong, D F; Xu, C L

    2014-01-01

    To better understand the structures of active-region filaments and the eruption process, we study an active-region filament eruption in active region NOAA 11082 in detail on June 22, 2010. Before the filament eruption, the opposite unidirectional material flows appeared in succession along the spine of the filament. The rising of the filament triggered two B-class flares at the upper part of the filament. As the bright material was injected into the filament from the sites of the flares, the filament exhibited a rapid uplift accompanying the counterclockwise rotation of the filament body. From the expansion of the filament, we can see that the filament is consisted of twisted magnetic field lines. The total twist of the filament is at least 5$\\pi$ obtained by using time slice method. According to the morphology change during the filament eruption, it is found that the active-region filament was a twisted flux rope and its unwinding motion was like a solar tornado. We also find that there was a continuous magn...

  4. SNS Devices With Pinhole-Defined Active Regions

    Hunt, Brian D.; Barner, Jeffrey B.

    1996-01-01

    Superconductor/normal conductor/superconductor (SNS) microbridge devices with pinhole-defined active regions undergoing development. Device includes thin, electrically insulating layer deposited epitaxially, with controlled formation of pinholes, on one of two superconducting layers. Normally conducting metal deposited epitaxially in pinholes and on insulating layer, forming electrical contact between two superconducting layers. Junction resistances and maximum junction voltages expected to be increased.

  5. Helicity of Solar Active Regions from a Dynamo Model

    Piyali Chatterjee

    2006-06-01

    We calculate helicities of solar active regions based on the idea that poloidal flux lines get wrapped around a toroidal flux tube rising through the convection zone, thereby giving rise to the helicity. We use our solar dynamo model based on the Babcock–Leighton -effect to study how helicity varies with latitude and time.

  6. The transcriptionally active regions in the genome of Bacillus subtilis

    Rasmussen, Simon; Nielsen, Henrik Bjørn; Jarmer, Hanne Østergaard

    2009-01-01

    The majority of all genes have so far been identified and annotated systematically through in silico gene finding. Here we report the finding of 3662 strand-specific transcriptionally active regions (TARs) in the genome of Bacillus subtilis by the use of tiling arrays. We have measured the genome...

  7. Unwinding motion of a twisted active region filament

    Yan, X. L.; Xue, Z. K.; Kong, D. F. [Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011 (China); Liu, J. H. [Department of Physics, Shijiazhuang University, Shijiazhuang 050035 (China); Xu, C. L. [Yunnan Normal University, Kunming 650092 (China)

    2014-12-10

    To better understand the structures of active region filaments and the eruption process, we study an active region filament eruption in active region NOAA 11082 in detail on 2010 June 22. Before the filament eruption, the opposite unidirectional material flows appeared in succession along the spine of the filament. The rising of the filament triggered two B-class flares at the upper part of the filament. As the bright material was injected into the filament from the sites of the flares, the filament exhibited a rapid uplift accompanying the counterclockwise rotation of the filament body. From the expansion of the filament, we can see that the filament consisted of twisted magnetic field lines. The total twist of the filament is at least 5π obtained by using a time slice method. According to the morphology change during the filament eruption, it is found that the active region filament was a twisted flux rope and its unwinding motion was like a solar tornado. We also find that there was a continuous magnetic helicity injection before and during the filament eruption. It is confirmed that magnetic helicity can be transferred from the photosphere to the filament. Using the extrapolated potential fields, the average decay index of the background magnetic fields over the filament is 0.91. Consequently, these findings imply that the mechanism of solar filament eruption could be due to the kink instability and magnetic helicity accumulation.

  8. Inferred flows of electric currents in solar active regions

    Techniques to identify sources of major current systems in active regions and their channels of flow are explored. Measured photospheric vector magnetic fields together with high resolution white light and H-alpha photographs provide the data base to derive the current systems in the photosphere and chromosphere of a solar active region. Simple mathematical constructions of active region fields and currents are used to interpret these data under the assumptions that the fields in the lower atmosphere (below 200 km) may not be force free but those in the chromosphere and higher are. The results obtained for the complex active region AR 2372 are: (1) Spots exhibiting significant spiral structure in the penumbral filaments were the source of vertical currents at the photospheric surface; (2) Magnetic neutral lines where the transverse magnetic field was strongly sheared were channels along which a strong current system flowed; (3) The inferred current systems produced a neutral sheet and oppositely-flowing currents in the area of the magnetic delta configuration that was the site of flaring

  9. Enhanced ULF electromagnetic activity detected by DEMETER above seismogenic regions

    Athanasiou, M; David, C; Anagnostopoulos, G

    2013-01-01

    In this paper we present results of a comparison between ultra low frequency (ULF) electromagnetic (EM) radiation, recorded by an electric field instrument (ICE) onboard the satellite DEMETER in the topside ionosphere, and the seismicity of regions with high and lower seiismic activity. In particular we evaluated the energy variations of the ULF Ez-electric field component during a period of four years (2006-2009), in order to examine check the possible relation of ULF EM radiation with seismogenic regions located in central America, Indonesia, Eastern Mediterranean Basin and Greece. As a tool of evaluating the ULF Ez energy variations we used Singular Spectrum Analysis (SSA) techniques. The results of our analysis clearly show a significant increase of the ULF EM energy emmited from regions of highest seismic activity at the tectonic plates boundaries. We interpret these results as suggesting that the highest ULF EM energy detected in the topside ionosphere is originated from seismic processes within Earth's...

  10. Full Stokes observations in the He I 1083 nm spectral region covering an M3.2 flare

    Kuckein, C.; Collados, M.; Sainz, R. Manso; Ramos, A. Asensio

    2015-01-01

    We present an exceptional data set acquired with the Vacuum Tower Telescope (Tenerife, Spain) covering the pre-flare, flare, and post-flare stages of an M3.2 flare. The full Stokes spectropolarimetric observations were recorded with the Tenerife Infrared Polarimeter in the He I 1083.0 nm spectral region. The object under study was active region NOAA 11748 on 2013 May 17. During the flare the chomospheric He I 1083.0 nm intensity goes strongly into emission. However, the nearby photospheric Si...

  11. Evidence for departure from a power-law flare size distribution for a small solar active region

    Wheatland, M. S.

    2010-01-01

    Active region 11029 was a small, highly flare-productive solar active region observed at a time of extremely low solar activity. The region produced only small flares: the largest of the $>70$ Geostationary Observational Environmental Satellite (GOES) events for the region has a peak 1--$8{\\AA}$ flux of $2.2\\times 10^{-6} {\\rm W} {\\rm m}^{-2}$ (GOES C2.2). The background-subtracted GOES peak-flux distribution suggests departure from power-law behavior above $10^{-6} {\\rm W} {\\rm m}^{-2}$, and...

  12. The lofting of Western Pacific regional aerosol by island thermodynamics as observed around Borneo

    N. H. Robinson

    2012-01-01

    Full Text Available Vertical profiles of aerosol chemical composition, number concentration and size were measured throughout the lower troposphere of Borneo, a large tropical island in the western Pacific Ocean. Aerosol composition, size and number concentration measurements (using an Aerodyne Aerosol Mass Spectrometer, Passive Cavity Aerosol Spectrometer Probe and Condensation Particle Counter, respectively were made both upwind and downwind of Borneo, as well as over the island itself, on board the UK BAe-146 research aircraft as part of the OP3 project. Two meteorological regimes were identified – one dominated by isolated terrestrial convection (ITC which peaked in the afternoon, and the other characterised by more regionally active mesoscale convective systems (MCS. Upwind profiles show aerosol to be confined to a shallow marine boundary layer below 930 ± 10 hPa (~760 m above sea level, a.s.l.. As this air mass advects over the island with the mean free troposphere synoptic flow during the ITC-dominated regime, it is convectively lofted above the terrestrial surface mixed layer to heights of between 945 ± 22 (~630 m a.s.l. and 740 ± 44 hPa (~2740 m a.s.l., consistent with a coupling between the synoptic steering level flow and island sea breeze circulations. Terrestrial aerosol was observed to be lofted into this higher layer through both moist convective uplift and transport through turbulent diurnal sea-breeze cells. At the peak of convective activity in the mid-afternoons, organic aerosol loadings in the lofted layer were observed to be substantially higher than in the morning (by a mean factor of three. This organic matter is dominated by secondary aerosol from processing of biogenic gas phase precursors. Aerosol number concentration profiles suggest formation of new particles aloft in the atmosphere. By the time the air mass reaches the west coast of the island, terrestrial aerosol is enhanced in the lofted layer. Such uplift of aerosol in Borneo is

  13. Centro Regional de Ciencias Nucleares (a Brazilian regional center for nuclear sciences) - activities report - 1999

    The annual activities report of 1999 of nuclear sciences regional center - Brazilian organization - introduces the next main topics: institutional relations; sectorial actions - logistic support and training, laboratory of radiation protection and dosimetry, laboratory of metrology, laboratory of chemical characterization; technical and scientific events; and financial resources and perspectives for 2000

  14. HINODE X-RAY TELESCOPE DETECTION OF HOT EMISSION FROM QUIESCENT ACTIVE REGIONS: A NANOFLARE SIGNATURE?

    The X-Ray Telescope (XRT) on the Japanese/USA/UK Hinode (Solar-B) spacecraft has detected emission from a quiescent active region core that is consistent with nanoflare heating. The fluxes from 10 broadband X-ray filters and filter combinations were used to construct differential emission measure (DEM) curves. In addition to the expected active region peak at log T = 6.3-6.5, we find a high-temperature component with significant emission measure at log T > 7.0. This emission measure is weak compared to the main peak-the DEM is down by almost three orders of magnitude-which accounts of the fact that it has not been observed with earlier instruments. It is also consistent with spectra of quiescent active regions: no Fe XIX lines are observed in a CHIANTI synthetic spectrum generated using the XRT DEM distribution. The DEM result is successfully reproduced with a simple two-component nanoflare model.

  15. Statistical study of network jets observed in the solar transition region: A comparison between coronal holes and quiet sun regions

    Narang, Nancy; Tian, Hui; Banerjee, Dipankar; Cranmer, Steven R; DeLuca, Ed E; McKillop, Sean

    2016-01-01

    Recent IRIS observations have revealed a prevalence of intermittent small-scale jets with apparent speeds of 80 - 250 km s$^{-1}$, emanating from small-scale bright regions inside network boundaries of coronal holes. We find that these network jets appear not only in coronal holes but also in quiet-sun regions. Using IRIS 1330A (C II) slit-jaw images, we extract several parameters of these network jets, e.g. apparent speed, length, lifetime and increase in foot-point brightness. Using several observations, we find that some properties of the jets are very similar but others are obviously different between the quiet sun and coronal holes. For example, our study shows that the coronal-hole jets appear to be faster and longer than those in the quiet sun. This can be directly attributed to a difference in the magnetic configuration of the two regions with open magnetic field lines rooted in coronal holes and magnetic loops often present in quiet sun. We have also detected compact bright loops, likely transition r...

  16. Active sonar, beaked whales and European regional policy.

    Dolman, Sarah J; Evans, Peter G H; Notarbartolo-di-Sciara, Giuseppe; Frisch, Heidrun

    2011-01-01

    Various reviews, resolutions and guidance from international and regional fora have been produced in recent years that acknowledge the significance of marine noise and its potential impacts on cetaceans. Within Europe, ACCOBAMS and ASCOBANS have shown increasing attention to the issue. The literature highlights concerns surrounding the negative impacts of active sonar on beaked whales in particular, where concerns primarily relate to the use of mid-frequency active sonar (1-10kHz), as used particularly in military exercises. The authors review the efforts that European regional policies have undertaken to acknowledge and manage possible negative impacts of active sonar and how these might assist the transition from scientific research to policy implementation, including effective management and mitigation measures at a national level. PMID:20451221

  17. Regional and national radiation protection activities in Egypt

    Radiation protection activities in Egypt go back to 1957 where the Egyptian Atomic Energy Commission (EAEC) Law was issued. Radiation protection and civil defense department was one of EAEC eighth departments. Ionizing radiation law was issued in 1960 and its executive regulation in 1962. The main aim of the present work is to through some light on the current radiation protection activities in Egypt. This includes not only the role of governmental organizations but also to the non governmental organizations. Currently a new Nuclear Safety law is understudy. Regional activities such as holding the second all African IRPA regional radiation protection congress which was held in April 2007 and national training and workshops are held regularly through EAEA, AAEA and MERRCAC. (author)

  18. Relevant Factors of Innovative Activities of Small Business in Regions

    Yelena Davidovna Vaysman

    2015-12-01

    Full Text Available The article discusses the system analysis aimed to identify the key reasons for the low innovation activity in the regions of the Russian Federation. The research is based on the hypothesis according to which the holism and systematic principles need to be applied for analyzing the reasons of the low innovative activity of small business in the regions,. To implement these principles, the authors have used the concept of «minimum number of descriptive levels of socio-economic system». In the research, the spiritual and cultural, cognitive, institutional, material and technological «layers» of the socio-economic system are investigated. The particular attention is paid to the cognitive and institutional segments. The methodological basis of the research is the methods of correlation and regression analysis, maps of positioning, integrated assessment, the author’s method of assessing the development of the knowledge-based economy and clustering. The quality of innovative small firms’ institutional environment is assessed using the resource approach. The authors have obtained the following results. The rate of demand growth for knowledge in the regions exceeded the growth rate of the regional offers of knowledge, including the innovative development of small businesses. A delayed reaction of the suppliers of innovative ideas to the corresponding demand is showed. The trend of differentiation increase of the Russian regions in terms of the knowledge-based economy’s development is revealed. A significant linear correlation of small firms’ innovative activities and the quality of institutional environment haven’t been discovered. It is shown that the regions are almost similar in the quality of basic socio-economic institutions, and more than 60 % of the regions have the intensity of small businesses’ innovation processes below the national average level. The obtained results allow to expand the scientific and methodological basis to

  19. The intermediate line region in active galactic nuclei

    Adhikari, T P; Czerny, B; Hryniewicz, K; Ferland, G J

    2016-01-01

    We show that the recently observed suppression of the gap between the broad line region (BLR) and the narrow line region (NLR) in some AGN can be fully explained by an increase of the gas density in the emitting region. Our model predicts the formation of the intermediate line region (ILR) that is observed in some Seyfert galaxies by the detection of emission lines with intermediate velocity full width half maximum (FWHM) $\\sim$ 700 - 1200 km s$^{-1}$. These lines are believed to be originating from an ILR located somewhere between the BLR and NLR. As it was previously proved, the apparent gap is assumed to be caused by the presence of dust beyond the sublimation radius. Our computations with the use of {\\sc cloudy} photoionization code, show that the differences in the shape of spectral energy distribution (SED) from the central region of AGN, do not diminish the apparent gap in the line emission in those objects. A strong discontinuity in the line emission vs radius exists for all lines at the dust sublimat...

  20. Signatures of Slow Solar Wind Streams from Active Regions in the Inner Corona

    Slemzin, V.; Harra, L.; Urnov, A.; Kuzin, S.; Goryaev, F.; Berghmans, D.

    2013-08-01

    The identification of solar-wind sources is an important question in solar physics. The existing solar-wind models ( e.g., the Wang-Sheeley-Arge model) provide the approximate locations of the solar wind sources based on magnetic field extrapolations. It has been suggested recently that plasma outflows observed at the edges of active regions may be a source of the slow solar wind. To explore this we analyze an isolated active region (AR) adjacent to small coronal hole (CH) in July/August 2009. On 1 August, Hinode/EUV Imaging Spectrometer observations showed two compact outflow regions in the corona. Coronal rays were observed above the active-region coronal hole (ARCH) region on the eastern limb on 31 July by STEREO-A/EUVI and at the western limb on 7 August by CORONAS- Photon/TESIS telescopes. In both cases the coronal rays were co-aligned with open magnetic-field lines given by the potential field source surface model, which expanded into the streamer. The solar-wind parameters measured by STEREO-B, ACE, Wind, and STEREO-A confirmed the identification of the ARCH as a source region of the slow solar wind. The results of the study support the suggestion that coronal rays can represent signatures of outflows from ARs propagating in the inner corona along open field lines into the heliosphere.

  1. HST observations of the LMC compact HII region N11A

    Heydari-Malayeri, M; Deharveng, L; Rosa, M R; Schärer, D; Zinnecker, H

    2001-01-01

    We present a study of the LMC compact HII region N11A using Hubble Space Telescope imaging observations which resolve N11A and reveal its unknown nebular and stellar features. The presence of a sharp ionization front extending over more than 4'' (1 pc) and fine structure filaments as well as larger loops indicate an environment typical of massive star formation regions, in agreement with high [OIII]/Hb line ratios. N11A is a young region, as deduced from its morphology, reddening, and especially high local concentration of dust, as indicated by the Balmer decrement map. Our observations also reveal a cluster of stars lying towards the central part of N11A. Five of the stars are packed in an area less than 2'' (0.5 pc), with the most luminous one being a mid O type star. N11A appears to be the most evolved compact HII region in the Magellanic Clouds so far studied.

  2. SOLAR TRANSITION REGION LINES OBSERVED BY THE INTERFACE REGION IMAGING SPECTROGRAPH: DIAGNOSTICS FOR THE O IV AND Si IV LINES

    The formation of the transition region O IV and Si IV lines observable by the Interface Region Imaging Spectrograph (IRIS) is investigated for both Maxwellian and non-Maxwellian conditions characterized by a κ-distribution exhibiting a high-energy tail. The Si IV lines are formed at lower temperatures than the O IV lines for all κ. In non-Maxwellian situations with lower κ, the contribution functions are shifted to lower temperatures. Combined with the slope of the differential emission measure, it is possible for the Si IV lines to be formed at very different regions of the solar transition region than the O IV lines; possibly close to the solar chromosphere. Such situations might be discernible by IRIS. It is found that photoexcitation can be important for the Si IV lines, but is negligible for the O IV lines. The usefulness of the O IV ratios for density diagnostics independently of κ is investigated and it is found that the O IV 1404.78 Å/1399.77 Å ratio provides a good density diagnostics except for very low T combined with extreme non-Maxwellian situations

  3. Cluster observations and theoretical identification of broadband waves in the auroral region

    M. Backrud-Ivgren

    2005-12-01

    Full Text Available Broadband waves are common on auroral field lines. We use two different methods to study the polarization of the waves at 10 to 180 Hz observed by the Cluster spacecraft at altitudes of about 4 Earth radii in the nightside auroral region. Observations of electric and magnetic wave fields, together with electron and ion data, are used as input to the methods. We find that much of the wave emissions are consistent with linear waves in homogeneous plasma. Observed waves with a large electric field perpendicular to the geomagnetic field are more common (electrostatic ion cyclotron waves, while ion acoustic waves with a large parallel electric field appear in smaller regions without suprathermal (tens of eV plasma. The regions void of suprathermal plasma are interpreted as parallel potential drops of a few hundred volts.

  4. Recent activity of the regional geologic structures in western Slovenia

    Miloš Bavec

    2007-06-01

    Full Text Available Several important geological structures in the western Slovenia were identifiedas active and their activity was quantified. Geologic interpretation is based on the analysis of repeated leveling line campaigns data along the Sečovlje–Bled polygon. Taking intoaccount the limitations of the method – only the vertical component of displacement is measured – the following structures were identified as active:a juvenile syncline between Strunjan and Koper, the Kras Imbricate Structure, the Diva~a fault, the Ra{a fault, the Southalpine Front and the Julian Alps thrust. Vertical movement rate is relative, calculated with respect to the benchmark in Sečovlje. The largest uplift rate difference between Sečovlje and Bled is 7 mm/a.Vertical Geodynamic Activity (VGA is introduced as a link between geologic interpretation of geodetic measurements on one side and possible applications on the other as well as a mean of comparison between tectonically active regions.

  5. CORONAS-F observations of active phenomena on the sun

    Oraevsky, V. N.; Sobelman, I. I.; Zitnik, I. A.; Kuznetsov, V. D.; Stepanov, A. I.; Polishuk, G. M.; Kovilin, P. N.; Negoda, A. A.; Dranovsky, V. I.; Yatskiv, Ya. S.

    Complex observations in the framework of the CORONAS-F Mission aimed at the study of active phenomena inthe solar corona are described. The main features are given for the following experiments: (1) XUV-imaging spectroscopy with high temporal and spatial resolution, (2) X-ray spectroscopy, (3) X-ray and gamma-ray photometer/spectrometer, and (4) solar cosmic rays. Some new observational data on the structure and dynamics of flares and transient events are discussed along with their analysis.

  6. [Ne II] Observations of Gas Motions in Compact and Ultracompact H II Regions

    Zhu, Qingfeng; Jaffe, Daniel T; Richter, Matthew J; Greathouse, Thomas K

    2008-01-01

    We present high spatial and spectral resolution observations of sixteen Galactic compact and ultracompact H II regions in the [Ne II] 12.8 microns fine structure line. The small thermal width of the neon line and the high dynamic range of the maps provide an unprecedented view of the kinematics of compact and ultracompact H II regions. These observations solidify an emerging picture of the structure of ultracompact H II regions suggested in our earlier studies of G29.96-0.02 and Mon R2 IRS1; systematic surface flows, rather than turbulence or bulk expansion, dominate the gas motions in the H II regions. The observations show that almost all of the sources have significant (5-20 km/s) velocity gradients and that most of the sources are limb-brightened. In many cases, the velocity pattern implies tangential flow along a dense shell of ionized gas. None of the observed sources clearly fits into the categories of filled expanding spheres, expanding shells, filled blister flows, or cometary H II regions formed by ...

  7. Satellite observation of regional haze pollution over the North China Plain

    Tao, Minghui; Chen, Liangfu; Su, Lin; Tao, Jinhua

    2012-06-01

    Haze clouds often form over the North China Plain (NCP) of eastern China, where large amounts of aerosol particles and their precursors are emitted. To obtain general insights into regional pollution, a large-scale, long-term study was conducted using A-Train satellite observations, ground measurements, and meteorological data. Contrary to previous analyses, most of the haze clouds appeared to form abruptly (within 2-3 h). Case studies show that natural sources contribute significantly to the formation of regional haze. Dust plumes can mix with local pollutants, causing smog clouds to form abruptly, while moist airflows can cause widespread haze-fog pollution. The combined observations revealed highly inhomogeneous haze clouds, in terms of both vertical and horizontal distribution, leading to clear discrepancies between site measurements near the surface and satellite observations at the top of the atmosphere. Surprisingly, prevailing dust plumes, which are closely connected with the haze clouds, were observed in winter. Airborne dust and water vapor transported from outside the region are the main drivers of regional haze over the NCP. Accumulation of local pollutants also leads to common occurrences of urban smog; however, the occurrence of most haze clouds shows no obvious correlation with local pollution. Local- and regional-scale haze pollution are common over the NCP, but they have differing formation mechanisms, and contrasting chemical and physical properties. The present findings improve our understanding of heavy pollution over eastern China and its links to climate.

  8. Regional organisation of brain activity during paradoxical sleep (PS).

    Maquet, P; Ruby, P; Schwartz, S; Laureys, S; Albouy, G; Dang-Vu, T; Desseilles, M; Boly, M; Melchior, G; Peigneux, P

    2004-07-01

    Human brain function is regionally organised during paradoxical sleep (PS) in a very different way than during wakefulness or slow wave sleep. The important activity in the pons and in the limbic/paralimbic areas constitutes the key feature of the functional neuroanatomy of PS, together with a relative quiescence of prefrontal and parietal associative cortices. Two questions are still outstanding. What neurocognitive and neurophysiological mechanisms may explain this original organization of brain function during PS? How the pattern of regional brain function may relate to dream content? Although some clues are already available, the experimental answer to both questions is still pending. PMID:15493545

  9. The evolution and orientation of early cycle 22 active regions

    Cannon, Anne T.; Marquette, William H.

    1991-01-01

    The evolution of six major active regions which appeared during the first phase of the present solar cycle (cycle 22) has been studied. It was found that the northern hemisphere regions exhibited a broad range of evolutionary behavior in which the commonly accepted 'normal pattern' (whereby the follower flux moves preferentially polewards ahead of the leader flux) is represented at one end of the range. At the other end of the range, the leader flux is displaced polewards of the follower flux. In the latter cases equatorward extensions of the polar coronal hole are noted.

  10. Accessing the innermost regions of Active Galactic Nuclei

    Ros, E

    2006-01-01

    Very-long-baseline interferometry can image the parsec-scale structure of radio jets, but the accretion disk close to the black hole remains invisible. One way to probe this accretion flow is provided by X-ray flux density monitoring and spectroscopy. Here we report on preliminary results of a multi-band campaign on NGC1052 with the goal of combining both approaches to access to the innermost regions of this active galaxy and to establish a connection between the relativistic jets and the accretion region.

  11. Systematic redshifts in the quiet sun transition region and corona observed with SUMER on SOHO

    Brekke, P.; Hassler, D. M.; Wilhelm, K.

    1997-01-01

    The observations of systematic redshifts of the transition region and coronal lines, obtained with the solar ultraviolet measurements of emitted radiation (SUMER) device onboard the Solar and Heliospheric Observatory (SOHO), are reported on. The results indicate that the redshifts are present even in the upper transition region. The lack of systematic blue shifts in Mg X lines raises the question on the origin of the solar wind. The observations of the solar ultraviolet spectrum with high resolution spectrometers demonstrated that there is a need for improved measurements of laboratory wavelengths of a number of spectral elements.

  12. Modelling Carbon Radio Recombination Line observation towards the Ultra-Compact HII region W48A

    Jeyakumar, S

    2013-01-01

    We model Carbon Recombination Line (CRL) emission from the Photo Dissociation Region (PDR) surrounding the Ultra-Compact (UC) HII region W48A. Our modelling shows that the inner regions ($A_V \\sim 1$) of the CII layer in the PDR contribute significantly to the CRL emission. The dependence of line ratios of CRL emission with the density of the PDR and the far ultra-violet (FUV) radiation incident on the region is explored over a large range of these parameters that are typical for the environments of UCHII regions. We find that by observing a suitable set of CRLs it is possible to constrain the density of the PDR. If the neutral density in the PDR is high ($\\gtrsim 10^7$ \\cmthree) CRL emission is bright at high frequencies ($\\gtrsim 20$ GHz), and absorption lines from such regions can be detected at low frequencies ($\\lesssim 10$ GHz). Modelling CRL observations towards W48A shows that the UCHII region is embedded in a molecular cloud of density of about $4 \\times$ 10$^7$ \\cmthree.

  13. Observation of nanoscopic charge-transfer region at metal/MoS2 interface

    Suto, Ryota; Venugopal, Gunasekaran; Tashima, Keiichiro; Nagamura, Naoka; Horiba, Koji; Suemitsu, Maki; Oshima, Masaharu; Fukidome, Hirokazu

    2016-07-01

    2D materials are promising for next-generation device applications, such as flexible transistors. However, the devices using 2D materials as active layers cannot exhibit good performance. One of the causes is that electronic properties are influential to the interface with, for instance, metal contact due to an ultra-thinness of the 2D materials. We have, therefore, performed core-level photoelectron microscopy measurements to investigate the local electronic states at interfaces in a MoS2 field-effect transistor (FET). We detect a charge-transfer region (CTR) at the MoS2/metal-electrode interface, which expands over ∼500 nm with the electrostatic potential (energy shift) variation of ∼70 meV, which causes band bending in the MoS2 electronic structure with a Fermi level shift. The observed potential variation of the CTR is well reproduced by a simple calculation using Poisson’s approximation. Our results point to a potential way of understanding the interfacial effect of the MOS2/metal electrode on the device characteristics and performance.

  14. A Flare Observed in Coronal, Transition Region and Helium I 10830 \\AA\\ Emissions

    Zeng, Zhicheng; Cao, Wenda; Judge, Philip G

    2014-01-01

    On June 17, 2012, we observed the evolution of a C-class flare associated with the eruption of a filament near a large sunspot in the active region NOAA 11504. We obtained high spatial resolution filtergrams using the 1.6 m New Solar Telescope at the Big Bear Solar Observatory in broad-band TiO at 706 nm (bandpass:10 \\AA) and He I 10830 \\AA\\ narrow-band (bandpass: 0.5 \\AA, centered 0.25 \\AA\\ to the blue). We analyze the spatio-temporal behavior of the He I 10830 \\AA\\ data, which were obtained over a 90" X 90" field of view with a cadence of 10 sec. We also analyze simultaneous data from the Atmospheric Imaging Assembly and Extreme Ultraviolet Variability Experiment instruments on board the Solar Dynamics Observatory spacecraft, and data from Reuven Ramaty High Energy Solar Spectroscopic Imager and GOES spacecrafts. Non-thermal effects are ignored in this analysis. Several quantitative aspects of the data, as well as models derived using the "0D" Enthalpy-Based Thermal Evolution of Loops model (EBTEL: Klimchuk...

  15. CMOS Active Pixel Sensor Star Tracker with Regional Electronic Shutter

    Yadid-Pecht, Orly; Pain, Bedabrata; Staller, Craig; Clark, Christopher; Fossum, Eric

    1996-01-01

    The guidance system in a spacecraft determines spacecraft attitude by matching an observed star field to a star catalog....An APS(active pixel sensor)-based system can reduce mass and power consumption and radiation effects compared to a CCD(charge-coupled device)-based system...This paper reports an APS (active pixel sensor) with locally variable times, achieved through individual pixel reset (IPR).

  16. Evaluation of observation-fused regional air quality model results for population air pollution exposure estimation.

    Chen, Gang; Li, Jingyi; Ying, Qi; Sherman, Seth; Perkins, Neil; Rajeshwari, Sundaram; Mendola, Pauline

    2014-07-01

    In this study, Community Multiscale Air Quality (CMAQ) model was applied to predict ambient gaseous and particulate concentrations during 2001 to 2010 in 15 hospital referral regions (HRRs) using a 36-km horizontal resolution domain. An inverse distance weighting based method was applied to produce exposure estimates based on observation-fused regional pollutant concentration fields using the differences between observations and predictions at grid cells where air quality monitors were located. Although the raw CMAQ model is capable of producing satisfying results for O3 and PM2.5 based on EPA guidelines, using the observation data fusing technique to correct CMAQ predictions leads to significant improvement of model performance for all gaseous and particulate pollutants. Regional average concentrations were calculated using five different methods: 1) inverse distance weighting of observation data alone, 2) raw CMAQ results, 3) observation-fused CMAQ results, 4) population-averaged raw CMAQ results and 5) population-averaged fused CMAQ results. It shows that while O3 (as well as NOx) monitoring networks in the HRRs are dense enough to provide consistent regional average exposure estimation based on monitoring data alone, PM2.5 observation sites (as well as monitors for CO, SO2, PM10 and PM2.5 components) are usually sparse and the difference between the average concentrations estimated by the inverse distance interpolated observations, raw CMAQ and fused CMAQ results can be significantly different. Population-weighted average should be used to account for spatial variation in pollutant concentration and population density. Using raw CMAQ results or observations alone might lead to significant biases in health outcome analyses. PMID:24747248

  17. Continuous gravity observations at active volcanoes through superconducting gravimeters

    Carbone, Daniele; Greco, Filippo

    2016-04-01

    Continuous gravity measurements at active volcanoes are usually taken through spring gravimeters that are easily portable and do not require much power to work. However, intrinsic limitations dictate that, when used in continuous, these instruments do not provide high-quality data over periods longer than some days. Superconducting gravimeters (SG), that feature a superconducting sphere in a magnetic field as the proof mass, provide better-quality data than spring gravimeters, but are bigger and need mains electricity to work, implying that they cannot be installed close to the active structures of high volcanoes. An iGrav SG was installed on Mt. Etna (Italy) in September 2014 and has worked almost continuously since then. It was installed about 6km from the active craters in the summit zone of the volcano. Such distance is normally too much to observe gravity changes due to relatively fast (minutes to days) volcanic processes. Indeed, mass redistributions in the shallowest part of the plumbing system induce short-wavelength gravity anomalies, centered below the summit craters. Nevertheless, thanks to the high precision and long-term stability of SGs, it was possible to observe low-amplitude changes over a wide range of timescales (minutes to months), likely driven by volcanic activity. Plans are in place for the implementation of a mini-array of SGs at Etna.

  18. ALMA Observations of the Active Nucleus of NGC 7469

    Izumi, Takuma; Aalto, Susanne; Doi, Akihiro; Espada, Daniel; Fathi, Kambiz; Harada, Nanase; Hatsukade, Bunyo; Hattori, Takashi; Hsieh, Pei-Ying; Ikarashi, Soh; Imanishi, Masatoshi; Iono, Daisuke; Ishizuki, Sumio; Krips, Melanie; Martín, Sergio; Matsushita, Satoki; Meier, David S; Nagai, Hiroshi; Nakai, Naomasa; Nakajima, Taku; Nakanishi, Kouichiro; Nomura, Hideko; Regan, Michael W; Schinnerer, Eva; Sheth, Kartik; Takano, Shuro; Tamura, Yoichi; Terashima, Yuichi; Tosaki, Tomoka; Turner, Jean L; Umehata, Hideki; Wiklind, Tommy

    2015-01-01

    We present ALMA Cycle 1 observations of the central kpc region of the luminous type-1 Seyfert galaxy NGC 7469 with unprecedented high resolution (0.5$"$ $\\times$ 0.4$"$ = 165 pc $\\times$ 132 pc) at submillimeter wavelengths. Utilizing the wide-bandwidth of ALMA, we simultaneously obtained HCN(4-3), HCO$^+$(4-3), CS(7-6), and partially CO(3-2) line maps, as well as the 860 $\\mu$m continuum. The region consists of the central $\\sim$ 1$"$ component and the surrounding starburst ring with a radius of $\\sim$ 1.5$"$-2.5$"$. Several structures connect these components. Except for CO(3-2), these dense gas tracers are significantly concentrated towards the central $\\sim$ 1$"$, suggesting their suitability to probe the nuclear regions of galaxies. Their spatial distribution resembles well those of centimeter and mid-infrared continuum emissions, but it is anti-correlated with the optical one, indicating the existence of dust obscured star formation. The integrated intensity ratios of HCN(4-3)/HCO$^+$(4-3) and HCN(4-3)/...

  19. Entrepreneurial activity and regional development: an introduction to this special issue

    Maribel Guerrero; Iñaki Peña-Legazkue

    2013-01-01

    The main objective of this special issue is to analyze the relationship between entrepreneurial intention and entrepreneurial activity and its impact on regional development. The last convulsive decade, with expansionary and recessionary economic cycles, offers a good opportunity to study how economic cycles affect the propensity of becoming an entrepreneur and, in turn, to observe how entrepreneurial activity contributes to change (improvement) in the economy. Previous studies have analyzed ...

  20. Unsupervised segmentation of task activated regions in fmRI

    Røge, Rasmus; Madsen, Kristoffer Hougaard; Schmidt, Mikkel Nørgaard;

    2015-01-01

    maps of task induced functional activations. This requires strong knowledge and assumptions on the BOLD response as a function of activitation while smoothing in general enhances the statistical power but at the cost of spatial resolution. We propose a fully unsupervised approach for the extraction...... using a Gaussian Process prior while assuming the segmented functional maps are the same across subjects but having individual time-courses and noise variances. To improve inference we propose an enhanced split-merge procedure. We find that our approach well extracts the induced activity of a finger...... tapping fMRI paradigm with maps that well corresponds to a supervised group SPM analysis. We further find interesting regions that are not activated time locked to the paradigm. Demonstrating that we in a fully unsupervised manner are able to extract the task-induced activations forms a promising...

  1. ON THE STRENGTH OF THE HEMISPHERIC RULE AND THE ORIGIN OF ACTIVE-REGION HELICITY

    Wang, Y.-M., E-mail: yi.wang@nrl.navy.mil [Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States)

    2013-10-01

    Vector magnetograph and morphological observations have shown that the solar magnetic field tends to have negative (positive) helicity in the northern (southern) hemisphere, although only ∼60%-70% of active regions appear to obey this 'hemispheric rule'. In contrast, at least ∼80% of quiescent filaments and filament channels that form during the decay of active regions follow the rule. We attribute this discrepancy to the difficulty in determining the helicity sign of newly emerged active regions, which are dominated by their current-free component; as the transverse field is canceled at the polarity inversion lines, however, the axial component becomes dominant there, allowing a more reliable determination of the original active-region chirality. We thus deduce that the hemispheric rule is far stronger than generally assumed, and cannot be explained by stochastic processes. Earlier studies have shown that the twist associated with the axial tilt of active regions is too small to account for the observed helicity; here, both tilt and twist are induced by the Coriolis force acting on the diverging flow in the emerging flux tube. However, in addition to this east-west expansion about the apex of the loop, each of its legs must expand continually in cross section during its rise through the convection zone, thereby acquiring a further twist through the Coriolis force. Since this transverse pressure effect is not limited by drag or tension forces, the final twist depends mainly on the rise time, and may be large enough to explain the observed active-region helicity.

  2. Topological Tools For The Analysis Of Active Region Filament Stability

    DeLuca, Edward E.; Savcheva, A.; van Ballegooijen, A.; Pariat, E.; Aulanier, G.; Su, Y.

    2012-05-01

    The combination of accurate NLFFF models and high resolution MHD simulations allows us to study the changes in stability of an active region filament before a CME. Our analysis strongly supports the following sequence of events leading up to the CME: first there is a build up of magnetic flux in the filament through flux cancellation beneath a developing flux rope; as the flux rope develops a hyperbolic flux tube (HFT) forms beneath the flux rope; reconnection across the HFT raises the flux rope while adding addition flux to it; the eruption is triggered when the flux rope becomes torus-unstable. The work applies topological analysis tools that have been developed over the past decade and points the way for future work on the critical problem of CME initiation in solar active regions. We will present the uses of this approach, current limitations and future prospects.

  3. Improving Regulatory Bodies’ Activities in Africa Through Regional Cooperation

    The Forum of Nuclear Regulatory Bodies in Africa (FNRBA) is presented as a good regional platform that plays key role in assisting the establishment of regulatory bodies and in enhancing and sustaining their activities. The FNRBA is founded on the aspirations of its members and the lessons learned from other similar regulatory networks. To achieve its objectives, the FNRBA needs more partners to learn and enhance its activities effectively, and particularly in the domain of radioactive sources control. The FNRBA is open to all nuclear regulatory bodies in the region and is voluntary. This cooperation makes use of the triangular cooperation mechanism that involves advanced and less advanced countries working together with assistance from the IAEA and other partners in development. (author)

  4. Seismic Halos Around Active Regions: An MHD Theory

    Hanasoge, Shravan M.

    2007-01-01

    Comprehending the manner in which magnetic fields affect propagating waves is a first step toward constructing accurate helioseismic models of active region sub-surface structure and dynamics. Here, we present a numerical method to compute the linear interaction of waves with magnetic fields embedded in a solar-like stratified background. The ideal Magneto-Hydrodynamic (MHD) equations are solved in a 3-dimensional box that straddles the solar photosphere, extending from 35 Mm within to 1.2 Mm...

  5. Sign singularity and flares in solar active region NOAA 11158

    Sorriso-Valvo, Luca; De Vita, Gaetano; Kazachenko, Maria D.; Krucker, Sam; Primavera, Leonardo; Servidio, Sergio; Vecchio, Antonio; Welsch, Brian T.; Fisher, George H.; Lepreti, Fabio; Carbone, Vincenzo

    2015-01-01

    Solar Active Region NOAA 11158 has hosted a number of strong flares, including one X2.2 event. The complexity of current density and current helicity are studied through cancellation analysis of their sign-singular measure, which features power-law scaling. Spectral analysis is also performed, revealing the presence of two separate scaling ranges with different spectral index. The time evolution of parameters is discussed. Sudden changes of the cancellation exponents at the time of large flar...

  6. Early life stress affects limited regional brain activity in depression

    Du, Lian; Wang, Jingjie; Meng, Ben; Yong, Na; Yang, Xiangying; Huang, Qingling; Zhang, Yan; Yang, Lingling; Qu, Yuan; Chen, Zhu; Li, Yongmei; Lv, Fajin; Hu, Hua

    2016-01-01

    Early life stress (ELS) can alter brain function and increases the risk of major depressive disorder (MDD) in later life. This study investigated whether ELS contributes to differences in regional brain activity between MDD patients and healthy controls (HC), as measured by amplitude of low-frequency fluctuation (ALFF)/fractional (f)ALFF. Eighteen first-episode, treatment-naïve MDD patients and HC were assessed with the Childhood Trauma Questionnaire and resting-state functional magnetic reso...

  7. Regional distribution of SGLT activity in rat brain in vivo

    Yu, Amy S.; Hirayama, Bruce A.; Timbol, Gerald; Liu, Jie; Diez-Sampedro, Ana; Kepe, Vladimir; Satyamurthy, Nagichettiar; Huang, Sung-Cheng; Wright, Ernest M.; Barrio, Jorge R.

    2012-01-01

    Na+-glucose cotransporter (SGLT) mRNAs have been detected in many organs of the body, but, apart from kidney and intestine, transporter expression, localization, and functional activity, as well as physiological significance, remain elusive. Using a SGLT-specific molecular imaging probe, α-methyl-4-deoxy-4-[18F]fluoro-d-glucopyranoside (Me-4-FDG) with ex vivo autoradiography and immunohistochemistry, we mapped in vivo the regional distribution of functional SGLTs in rat brain. Since Me-4-FDG ...

  8. An Improved Virial Estimate of Solar Active Region Energy

    Wheatland, M. S.; Metcalf, T. R.

    2005-01-01

    The MHD virial theorem may be used to estimate the magnetic energy of active regions based on vector magnetic fields measured at the photosphere or chromosphere. However, the virial estimate depends on the measured vector magnetic field being force-free. Departure from force-freeness leads to an unknown systematic error in the virial energy estimate, and an origin dependence of the result. We present a method for estimating the systematic error by assuming that magnetic forces are confined to...

  9. On the filament motion in magnetic field of active regions

    The study of filament motion in magnetic field of active regions is fulfiled. Filament movement can possibly be presented as a drift in the crossed fields, but there exist fast movements that cannot be described as a drift. For very fast motion, with acceleration greater than that of free fall, it is sometimes necessary to assume, that the motion is carried out due to the filament's own electric current. A model, describing filament motion data, given by Mouradian M. is presented

  10. Validating Time-Distance Far-side Imaging of Solar Active Regions through Numerical Simulations

    Hartlep, Thomas; Zhao, Junwei; Mansour, Nagi N.; Kosovichev, Alexander G.

    2008-01-01

    Far-side images of solar active regions have become one of the routine products of helioseismic observations, and are of importance for space weather forecasting by allowing the detection of sunspot regions before they become visible on the Earth side of the Sun. An accurate assessment of the quality of the far-side maps is difficult, because there are no direct observations of the solar far side to verify the detections. In this paper we assess far-side imaging based on the time-distance hel...

  11. Signatures of the slow solar wind streams from active regions in the inner corona

    Slemzin, V; Urnov, A; Kuzin, S; Goryaev, F; Berghmans, D

    2012-01-01

    Some of local sources of the slow solar wind can be associated with spectroscopically detected plasma outflows at edges of active regions accompanied with specific signatures in the inner corona. The EUV telescopes (e.g. SPIRIT/CORONAS-F, TESIS/CORONAS-Photon and SWAP/PROBA2) sometimes observed extended ray-like structures seen at the limb above active regions in 1MK iron emission lines and described as "coronal rays". To verify the relationship between coronal rays and plasma outflows, we analyze an isolated active region (AR) adjacent to small coronal hole (CH) observed by different EUV instruments in the end of July - beginning of August 2009. On August 1 EIS revealed in the AR two compact outflows with the Doppler velocities V =10-30 km/s accompanied with fan loops diverging from their regions. At the limb the ARCH interface region produced coronal rays observed by EUVI/STEREO-A on July 31 as well as by TESIS on August 7. The rays were co-aligned with open magnetic field lines expanded to the streamer sta...

  12. 30 MHz radar observations of artificial E region field-aligned plasma irregularities

    D. L. Hysell

    2008-02-01

    Full Text Available Artificial E region field aligned irregularities (FAIs have been observed during heating experiments at the HAARP facility using a new 30 MHz coherent scatter radar imager deployed near Homer, Alaska. Irregularities were observed during brief experiments on three quiet days in July and August, 2007, when the daytime E region critical frequency was close to 3 MHz. Irregularities were consistently generated and detected during experiments with O-mode HF pumping on zenith with a 1-min on, 1-min off CW modulation. The scattering cross sections, rise, and fall times of the echoes were observed as well as their spectral properties. Results were found to be mainly in agreement with observations from other mid- and high-latitude sites with some discrepancies. Radar images of the irregularity-filled volume on one case exhibited clear variations in backscatter power and Doppler shift across the volume. The images furthermore show the emergence of a small irregularity-filled region to the south southwest of the main region in the approximate direction of magnetic zenith.

  13. Both novelty and expertise increase action observation network activity

    Sook-Lei eLiew

    2013-09-01

    Full Text Available Our experiences with others affect how we perceive their actions. In particular, activity in bilateral premotor and parietal cortices during action observation, collectively known as the action observation network (AON, is modulated by one’s expertise with the observed actions or individuals. However, conflicting reports suggest that AON activity is greatest both for familiar and unfamiliar actions. The current study examines the effects of different types and amounts of experience (e.g., visual, interpersonal, personal on AON activation. fMRI was used to scan 16 healthy participants without prior experience with individuals with amputations (novices, 11 experienced occupational therapists (OTs who had varying amounts of experience with individuals with amputations, and one individual born with below-elbow residual limbs (participant CJ, as they viewed video clips of goal-matched actions performed by an individual with residual limbs and by an individual with hands. Participants were given increased visual exposure to actions performed by both effectors midway through the scanning procedure. Novices demonstrated a large AON response to the initial viewing of an individual with residual limbs compared to one with hands, but this signal was attenuated after they received visual exposure to both effectors. In contrast, OTs, who had moderate familiarity with residual limbs, demonstrated a lower AON response upon initial viewing—similar to novices after they received visual exposure. At the other extreme, CJ, who has extreme familiarity with residual limbs both visually and motorically, shows a largely increased left-lateralized AON response, exceeding that of novices and experienced OTs, when viewing the residual limb compared to hand actions. These results suggest that a nuanced model of AON engagement is needed to explain how cases of both extreme experience (CJ and extreme novelty (novices can result in the greatest AON activity.

  14. Flux Emergence in the Solar Active Region NOAA 11158: The Evolution of Net Current

    Vemareddy, P; Karthikreddy, S

    2015-01-01

    We present a detailed investigation on the evolution of observed net vertical current using a time series of vector magnetograms of the active region (AR) NOAA 11158 obtained from Helioseismic Magnetic Imager. We also discuss the relation of net current to the observed eruptive events. The AR evolved from $\\beta\\gamma$ to $\\beta\\gamma\\delta$ configuration over a period of 6 days. The AR had two sub-regions of activity with opposite chirality: one dominated by sunspot rotation producing a strong CME, the other showing large shear motions producing a strong flare. The net current in each polarity over the CME producing sub-region increased to a maximum and then decreased when the sunspots got separated. The time profile of net current in this sub-region followed the time profile of the rotation rate of the S-polarity sunspot of the same sub-region. The net current in the flaring sub-region showed a sudden increase at the time of the strong flare and remained unchanged till the end of the observation, while the ...

  15. Combining GOSAT XCO2 observations over land and ocean to improve regional CO2 flux estimates

    Deng, Feng; Jones, Dylan B. A.; O'Dell, Christopher W.; Nassar, Ray; Parazoo, Nicholas C.

    2016-02-01

    We used the GEOS-Chem data assimilation system to examine the impact of combining Greenhouse Gases Observing Satellite (GOSAT) XCO2 data over land and ocean on regional CO2 flux estimates for 2010-2012. We found that compared to assimilating only land data, combining land and ocean data produced an a posteriori CO2 distribution that is in better agreement with independent data and fluxes that are in closer agreement with existing top-down and bottom-up estimates. Adding XCO2 data over oceans changed the tropical land regions from a source of 0.64 Pg C/yr to a sink of -0.60 Pg C/yr and produced a corresponding reduction in the estimated sink in northern and southern land regions by 0.49 Pg C/yr and 0.80 Pg C/yr, respectively. This highlights the importance of improved observational coverage in the tropics to better quantify the latitudinal distribution of the terrestrial fluxes. Based only on land XCO2 data, we estimated a strong source in northern tropical South America, which experienced wet conditions in 2010-2012. In contrast, with the land and ocean data, we estimated a sink for this wet region in the north, and a source for the seasonally dry regions in the south and east, which is consistent with our understanding of the impact of moisture availability on the carbon balance of the region. Our results suggest that using satellite data with a more zonally balanced observational coverage could help mitigate discrepancies in CO2 flux estimates; further improvement could be expected with the greater observational coverage provided by the Orbiting Carbon Observatory-2.

  16. Improving global fire carbon emissions estimates by combining moderate resolution burned area and active fire observations

    Randerson, J. T.; Chen, Y.; Giglio, L.; Rogers, B. M.; van der Werf, G.

    2011-12-01

    In several important biomes, including croplands and tropical forests, many small fires exist that have sizes that are well below the detection limit for the current generation of burned area products derived from moderate resolution spectroradiometers. These fires likely have important effects on greenhouse gas and aerosol emissions and regional air quality. Here we developed an approach for combining 1km thermal anomalies (active fires; MOD14A2) and 500m burned area observations (MCD64A1) to estimate the prevalence of these fires and their likely contribution to burned area and carbon emissions. We first estimated active fires within and outside of 500m burn scars in 0.5 degree grid cells during 2001-2010 for which MCD64A1 burned area observations were available. For these two sets of active fires we then examined mean fire radiative power (FRP) and changes in enhanced vegetation index (EVI) derived from 16-day intervals immediately before and after each active fire observation. To estimate the burned area associated with sub-500m fires, we first applied burned area to active fire ratios derived solely from within burned area perimeters to active fires outside of burn perimeters. In a second step, we further modified our sub-500m burned area estimates using EVI changes from active fires outside and within of burned areas (after subtracting EVI changes derived from control regions). We found that in northern and southern Africa savanna regions and in Central and South America dry forest regions, the number of active fires outside of MCD64A1 burned areas increased considerably towards the end of the fire season. EVI changes for active fires outside of burn perimeters were, on average, considerably smaller than EVI changes associated with active fires inside burn scars, providing evidence for burn scars that were substantially smaller than the 25 ha area of a single 500m pixel. FRP estimates also were lower for active fires outside of burn perimeters. In our

  17. Observations of regional and local variability in the optical properties of maritime clouds

    White, A.B. [Univ. of Colorado at Boulder/National Oceanic and Atmospheric Administration, Boulder, CO (United States); Fairall, C.W. [Environmental Technology Lab., Boulder, CO (United States)

    1996-04-01

    White and Fairall (1995) calculated the optical properties of the marine boundary layer (MBL) clouds observed during the Atlantic Stratocumulus Transition Experiment (ASTEX) and compared their results with the results obtained by Fairall et al. for the MBL clouds observed during the First International Satellite Climatology Program (ISSCP) Regional Experiment (FIRE). They found a factor of two difference in the optical depth versus liquid water relationship that applies to the clouds observed in each case. In the present study, we present evidence to support this difference. We also investigate the local variability exhibited in the ASTEX optical properties using measurements of the boundary layer aerosol concentration.

  18. Submillimeter Array multiline observations of the massive star-forming region IRAS 18089-1732

    Beuther, H.; Q. Zhang; Hunter, T.R.; Sridharan, T. K.; Zhao, J.-H.; Sollins, P.; Ho, P. T. P.; Liu, S.-Y.; Ohashi, N; Su, Y. N.; Lim, J

    2004-01-01

    Submillimeter Array (SMA) observations of the high-mass star-forming region IRAS 18089-1732 in the 1 mm and 850 $\\mu$m band with 1 GHz bandwidth reveal a wealth of information. We present the observations of 34 lines from 16 different molecular species. Most molecular line maps show significant contributions from the outflow, and only few molecules are confined to the inner core. We present and discuss the molecular line observations and outline the unique capabilities of the SMA for future i...

  19. Ionospheric Variations in the Region of the Equatorial Ionization Anomaly Crest: Comparison Between Observations and IRI-2012 Model Predictions.

    Oyeyemi, E. O.; Bolaji, S.; Adewale, A. O.; Akala, A. O.; Oladipo, O. A.; Olugbon, B.; Olawepo, O. A.; Adeniyi, J. O.; Adimula, I.

    2015-12-01

    The objective of this work is to study the variations of the F2-layer critical frequency (foF2) in the region of equatorial ionization anomaly crest and check the accuracy of International Reference Ionosphere (IRI-2012) model predictions using ionosonde measurements from a number of stations in this region. We have used data, based on availability, corresponding to different seasonal and solar activity periods from each station considered to carry out our investigations. Details of the statistical analysis using percentage deviation (PD), upper and lower inter-quartile range (IQR) and relative deviation module mean (RDMM) for the evaluation of the IRI model performance are presented. The results show that, generally, the IRI model predictions have agreement with the observed values in terms of the pattern of variations but there are number of cases where IRI model overestimates and underestimates the observed values. Results from this study will be of help to improving prediction ability of the IRI models.

  20. Fostering Earth Observation Regional Networks - Integrative and iterative approaches to capacity building

    Habtezion, S.

    2015-12-01

    Fostering Earth Observation Regional Networks - Integrative and iterative approaches to capacity building Fostering Earth Observation Regional Networks - Integrative and iterative approaches to capacity building Senay Habtezion (shabtezion@start.org) / Hassan Virji (hvirji@start.org)Global Change SySTem for Analysis, Training and Research (START) (www.start.org) 2000 Florida Avenue NW, Suite 200 Washington, DC 20009 USA As part of the Global Observation of Forest and Land Cover Dynamics (GOFC-GOLD) project partnership effort to promote use of earth observations in advancing scientific knowledge, START works to bridge capacity needs related to earth observations (EOs) and their applications in the developing world. GOFC-GOLD regional networks, fostered through the support of regional and thematic workshops, have been successful in (1) enabling participation of scientists for developing countries and from the US to collaborate on key GOFC-GOLD and Land Cover and Land Use Change (LCLUC) issues, including NASA Global Data Set validation and (2) training young developing country scientists to gain key skills in EOs data management and analysis. Members of the regional networks are also engaged and reengaged in other EOs programs (e.g. visiting scientists program; data initiative fellowship programs at the USGS EROS Center and Boston University), which has helped strengthen these networks. The presentation draws from these experiences in advocating for integrative and iterative approaches to capacity building through the lens of the GOFC-GOLD partnership effort. Specifically, this presentation describes the role of the GODC-GOLD partnership in nurturing organic networks of scientists and EOs practitioners in Asia, Africa, Eastern Europe and Latin America.

  1. ISO Mid-Infrared Observations of Giant HII Regions in M33

    Skelton, B. P.; Waller, W. H.; Hodge, P. W.; Boulanger, F.; Cornett, R. H.; Fanelli, M. N.; Lequeux, J.; Stecher, T. P.; Viallefond, F.; Hui, Y.

    1999-01-01

    We present Infrared Space Observatory Camera (ISOCAM) Circular Variable Filter scans of three giant HII regions in M33. IC 133, NGC 595, and CC 93 span a wide range of metallicity, luminosity, nebular excitation, and infrared excess; three other emission regions (CC 43, CC 99, and a region to the northeast of the core of NGC 595) are luminous enough in the mid-infrared to be detected in the observed fields. ISOCAM CVF observations provide spatially resolved observations (5'') of 151 wavelengths between 5.1 and 16.5 microns with a spectral resolution R = 35 to 50. We observe atomic emission lines ([Ne II], [Ne III], and [S IV]), several "unidentified infrared bands" (UIBs; 6.2, 7.7, 8.6, 11.3, 12.0, and 12.7 microns), and in some cases a continuum which rises steeply at longer wavelengths. We conclude that the spectra of these three GHRs are well explained by combinations of ionized gas, PAHs, and very small grains in various proportions and with different spatial distributions. Comparisons between observed ratios of the various UIBs with model ratios indicate that the PAHs in all three of the GHRs are dehydrogenated and that the small PAHs have been destroyed in IC 133 but have survived in NGC 595 and CC 93. The [Ne III]/[Ne II] ratios observed in IC 133 and NGC 595 are consistent with their ages of 5 and 4.5 Myr, respectively; the deduced ionization parameter is higher in IC 133, consistent with its more compact region of emission.

  2. Flux emergence in the solar active region NOAA 11158: the evolution of net current

    We present a detailed investigation of the evolution of observed net vertical current using a time series of vector magnetograms of the active region (AR) NOAA 11158 obtained from the Helioseismic and Magnetic Imager. We also discuss the relation of net current to the observed eruptive events. The AR evolved from the βγ to βγδ configuration over a period of six days. The AR had two sub-regions of activity with opposite chirality: one dominated by sunspot rotation producing a strong CME, and the other showing large shear motions producing a strong flare. The net current in each polarity over the CME producing sub-region increased to a maximum and then decreased when the sunspots were separated. The time profile of net current in this sub-region followed the time profile of the rotation rate of the south-polarity sunspot in the same sub-region. The net current in the flaring sub-region showed a sudden increase at the time of the strong flare and remained unchanged until the end of the observation, while the sunspots maintained their close proximity. The systematic evolution of the observed net current is seen to follow the time evolution of total length of strongly sheared polarity inversion lines in both of the sub-regions. The observed photospheric net current could be explained as an inevitable product of the emergence of a twisted flux rope, from a higher pressure confinement below the photosphere into the lower pressure environment of the photosphere. (paper)

  3. Insights from Synthetic Star-forming Regions: I. Reliable Mock Observations from SPH Simulations

    Koepferl, Christine M; Dale, James E; Biscani, Francesco

    2016-01-01

    Through synthetic observations of a hydrodynamical simulation of an evolving star-forming region, we assess how the choice of observational techniques affects the measurements of properties which trace star formation. Testing and calibrating observational measurements requires synthetic observations which are as realistic as possible. In this part of the paper series (Paper I), we explore different techniques for how to map the distributions of densities and temperatures from the particle-based simulations onto a Voronoi mesh suitable for radiative transfer and consequently explore their accuracy. We further test different ways to set up the radiative transfer in order to produce realistic synthetic observations. We give a detailed description of all methods and ultimately recommend techniques. We have found that the flux around 20 microns is strongly overestimated when blindly coupling the dust radiative transfer temperature with the hydrodynamical gas temperature. We find that when instead assuming a consta...

  4. Is Brain Activity during Action Observation Modulated by the Perceived Fairness of the Actor?

    Joset A Etzel

    Full Text Available Perceiving other people's actions triggers activity in premotor and parietal areas, brain areas also involved in executing and sensing our own actions. Paralleling this phenomenon, observing emotional states (including pain in others is associated with activity in the same brain areas as activated when experiencing similar emotions directly. This emotion perception associated activity has been shown to be affected by the perceived fairness of the actor, and in-group membership more generally. Here, we examine whether action observation associated brain activity is also affected by the perceived social fairness of the actors. Perceived fairness was manipulated using an alternating iterated Prisoner's Dilemma game between the participant and two confederates, one of whom played fairly and the other unfairly. During fMRI scanning the participants watched movies of the confederates performing object-directed hand actions, and then performed hand actions themselves. Mass-univariate analysis showed that observing the actions triggered robust activation in regions associated with action execution, but failed to identify a strong modulation of this activation based on perceived fairness. Multivariate pattern analysis, however, identified clusters potentially carrying information about the perceived fairness of the actor in the middle temporal gyrus, left postcentral gyrus, right inferior parietal lobule, right middle cingulate cortex, right angular gyrus, and right superioroccipital gyrus. Despite being identified by a whole-brain searchlight analysis (and so without anatomical restriction, these clusters fall into areas frequently associated with action observation. We conclude that brain activity during action observation may be modulated by perceived fairness, but such modulation is subtle; robust activity is associated with observing the actions of both fair and unfair individuals.

  5. Is Brain Activity during Action Observation Modulated by the Perceived Fairness of the Actor?

    Etzel, Joset A; Valchev, Nikola; Gazzola, Valeria; Keysers, Christian

    2016-01-01

    Perceiving other people's actions triggers activity in premotor and parietal areas, brain areas also involved in executing and sensing our own actions. Paralleling this phenomenon, observing emotional states (including pain) in others is associated with activity in the same brain areas as activated when experiencing similar emotions directly. This emotion perception associated activity has been shown to be affected by the perceived fairness of the actor, and in-group membership more generally. Here, we examine whether action observation associated brain activity is also affected by the perceived social fairness of the actors. Perceived fairness was manipulated using an alternating iterated Prisoner's Dilemma game between the participant and two confederates, one of whom played fairly and the other unfairly. During fMRI scanning the participants watched movies of the confederates performing object-directed hand actions, and then performed hand actions themselves. Mass-univariate analysis showed that observing the actions triggered robust activation in regions associated with action execution, but failed to identify a strong modulation of this activation based on perceived fairness. Multivariate pattern analysis, however, identified clusters potentially carrying information about the perceived fairness of the actor in the middle temporal gyrus, left postcentral gyrus, right inferior parietal lobule, right middle cingulate cortex, right angular gyrus, and right superioroccipital gyrus. Despite being identified by a whole-brain searchlight analysis (and so without anatomical restriction), these clusters fall into areas frequently associated with action observation. We conclude that brain activity during action observation may be modulated by perceived fairness, but such modulation is subtle; robust activity is associated with observing the actions of both fair and unfair individuals. PMID:26820995

  6. Statistical study of atmospheric gravity waves in the mesopause region observed by a lidar chain in eastern China

    Gong, Shaohua; Yang, Guotao; Dou, Xiankang; Xu, Jiyao; Chen, Chunxia; Gong, Shunsheng

    2015-08-01

    Atmospheric gravity wave activities in the mesopause region have been observed and statistically investigated with a sodium lidar chain in eastern China. In total, there were 471 gravity waves identified from over 5400 h of observations at Hainan (19.99°N, 110.34°E), Hefei (31.87°N, 117.23°E), and Beijing (40.47°N, 115.97°E). These waves typically had vertical wavelengths of λz = 2 - 4 km, observed periods of Tob = 1 - 4 h, amplitude growth factors of β = - 0.025 ~ + 0.05 km-1, and wave amplitudes of Aeβ * 90km = 1.5 - 6 %. Strong systematic parameter relationships were found, and they agree with the predictions of diffusive filtering theory. Statistical results show that the seasonal variability of gravity wave activity had a summer-maximum and winter-minimum characteristics in the mesopause region over eastern China. A qualitative interpretation is proposed regarding the seasonal and geographic variability observed by the lidar chain, based on analysis of source properties and influences from background wind, which vary by season.

  7. Magnetic Nonpotentiality in Photospheric Active Regions as a Predictor of Solar Flares

    Yang, Xiao; Zhang, HongQi; Mao, XinJie

    2013-01-01

    Based on several magnetic nonpotentiality parameters obtained from the vector photospheric active region magnetograms obtained with the Solar Magnetic Field Telescope at the Huairou Solar Observing Station over two solar cycles, a machine learning model has been constructed to predict the occurrence of flares in the corresponding active region within a certain time window. The Support Vector Classifier, a widely used general classifier, is applied to build and test the prediction models. Several classical verification measures are adopted to assess the quality of the predictions. We investigate different flare levels within various time windows, and thus it is possible to estimate the rough classes and erupting times of flares for particular active regions. Several combinations of predictors have been tested in the experiments. The True Skill Statistics are higher than 0.36 in 97% of cases and the Heidke Skill Scores range from 0.23 to 0.48. The predictors derived from longitudinal magnetic fields do perform ...

  8. Observation of Andreev bound states at spin-active interfaces

    Beckmann, Detlef; Wolf, Michael Johannes [KIT, Institut fuer Nanotechnologie (Germany); Huebler, Florian [KIT, Institut fuer Nanotechnologie (Germany); KIT, Institut fuer Festkoerperphysik (Germany); Loehneysen, Hilbert von [KIT, Institut fuer Festkoerperphysik (Germany); KIT, Physikalisches Institut (Germany)

    2013-07-01

    We report on high-resolution differential conductance experiments on nanoscale superconductor/ferromagnet tunnel junctions with ultra-thin oxide tunnel barriers. We observe subgap conductance features which are symmetric with respect to bias, and shift according to the Zeeman energy with an applied magnetic field. These features can be explained by resonant transport via Andreev bound states induced by spin-active scattering at the interface. From the energy and the Zeeman shift of the bound states, both the magnitude and sign of the spin-dependent interfacial phase shifts between spin-up and spin-down electrons can be determined. These results contribute to the microscopic insight into the triplet proximity effect at spin-active interfaces.

  9. Energy balance in solar active regions - The dip of April, 1985

    Hudson, H. S.

    1986-01-01

    The presence of a solar active region affects the luminosity of the sun. Sunspots directly produce 'dips' in the total solar irradiance approximately proportionally to their projected area, while faculae produce excess energy. These effects were discovered during the solar maximum period of 1980, and the sunspot effect during solar minimum is examined. The 'dip' due to an active region in April, 1985, as observed in the total solar irradiance by the ACRIM instrument on the Solar Maximum Mission is examined. These data (obtained after the spacecraft repair in May, 1984) have simple variations, relative to those observed in 1980, because of the reduced level of activity approaching solar minimum. It is found that the PSI index of projected sunspot area as defined in 1980 appears to describe this 'dip' satisfactorily.

  10. ACTIVE OBSERVATION TACTICS IN PATIENTS WITH KIDNEY NEOPLASMS

    B. Ya. Alekseev

    2012-01-01

    Full Text Available As of now, about 40-60% of the first detected kidney tumors are accidentally diagnosed. These are most often asymptomatic small kidney tumors (SKT without distant metastases; 15–20% of them are benign. A number of studies have revealed that kidney malignant tumors grow slowly and spread extremely rarely, as evidenced by a histological study. These and other data formed the basis for the active observation tactic that became possible and acceptable in well-selected patients, in elderly patients with SKT and severe comorbidity in particular.

  11. High resolution radio observations of nuclear and circumnuclear regions of luminous infrared galaxies (LIRGs)

    High-resolution radio observations of the nuclear region of Luminous and Ultraluminous Infrared Galaxies (ULIRGs) have shown that its radio structure consists of a compact high surface-brightness central radio source immersed in a diffuse low brightness circumnuclear halo. While the central component could be associated with an AGN or compact star-forming regions where radio supernovae are exploding, it is well known that the circumnuclear regions host bursts of star-formation. The studies of radio supernovae can provide essential information about stellar evolution and CSM/ISM properties in regions hidden by dust at optical and IR wavelengths. In this contribution, we show results from radio interferometric observations from NGC 7469, IRAS 18293-3413 and IRAS 17138-1017 where three extremely bright radio supernovae have been found. High-resolution radio observations of these and other LIRGs would allow us to determine the core-collapse supernova rate in them as well as their star-formation rate.

  12. Post-outburst radio observation of the region around McNeil's nebula (V1647 Ori)

    Vig, S; Kulkarni, V K; Ojha, D K

    2005-01-01

    We present post-outburst (~ 100 days after outburst) radio continuum observation of the region (~ 30' x 30') around McNeil's nebula (V1647 Orionis). The observations were carried out using the Giant Metrewave Radio Telescope (GMRT), India, at 1272 MHz on 2004 Feb 14.5 UT. Although 8 sources have been detected within a circular diameter of 25' centred on V1647 Ori, we did not detect any radio continuum emission from McNeil's nebula. We assign a 5-sigma upper limit of 0.15 mJy/beam for V1647 Ori where the beam size is 5.6" x 2.7". Even at higher frequencies of 4.9 and 8.5 GHz (VLA archival data), no radio emission has been detected from this region. Three scenarios namely, emission from homogeneous HII region, ionised stellar wind and shock ionised gas, are explored in the light of our GMRT upper-limit. For the case of homogeneous HII region, the radius of the emitting region is constrained to be ~ 2,500 K, which is consistent with the reported radio and H-alpha emission. In the ionised stellar wind picture, ou...

  13. Monitoring rice farming activities in the Mekong Delta region

    Nguyen, S. T.; Chen, C. F.; Chen, C. R.; Chiang, S. H.; Chang, L. Y.; Khin, L. V.

    2015-12-01

    Half of the world's population depends on rice for survival. Rice agriculture thus plays an important role in the developing world's economy. Vietnam is one of the largest rice producers and suppliers on earth and more than 80% of the exported rice was produced from the Mekong Delta region, which is situated in the southwestern Vietnam and encompasses approximately 40,000 km2. Changes in climate conditions could likely trigger the increase of insect populations and rice diseases, causing the potential loss of rice yields. Monitoring rice-farming activities through crop phenology detection can provide policymakers with timely strategies to mitigate possible impacts on the potential yield as well as rice grain exports to ensure food security for the region. The main objective of this study is to develop a logistic-based algorithm to investigate rice sowing and harvesting activities from the multi-temporal Moderate Resolution Imaging Spectroradiometer (MODIS)-Landsat fusion data. We processed the data for two main cropping seasons (i.e., winter-spring and summer-autumn seasons) through a three-step procedure: (1) MODIS-Landsat data fusion, (2) construction of the time-series enhanced vegetation index 2 (EVI2) data, (3) rice crop phenology detection. The EVI2 data derived from the fusion results between MODIS and Landsat data were compared with that of Landsat data indicated close correlation between the two datasets (R2 = 0.93). The time-series EVI2 data were processed using the double logistic method to detect the progress of sowing and harvesting activities in the region. The comparisons between the estimated sowing and harvesting dates and the field survey data revealed the root mean squared error (RMSE) values of 8.4 and 5.5 days for the winter-spring crop and 9.4 and 12.8 days for the summer-autumn crop, respectively. This study demonstrates the effectiveness of the double logistic-based algorithm for rice crop monitoring from temporal MODIS-Landsat fusion data

  14. Dielectric Constant of Titan's South Polar Region from Cassini Radio Science Bistatic Scattering Observations

    Marouf, E.; Rappaport, N.; French, R.; Simpson, R.; Kliore, A.; McGhee, C.; Schinder, P.; Anabtawi, A.

    2008-12-01

    Four out of six Radio Science bistatic scattering (bistatic-radar) observations of Titan's surface completed during the Cassini nominal mission yielded detectable quasi-specular 3.6 cm-λ (X-band) surface echoes, making Titan the most distant solar system object for which bistatic echoes have been successfully detected. Right circularly polarized sinusoidal signal was transmitted by Cassini and both the right and left circularly polarized (RCP and LCP) surface reflected components were observed at the 70-m stations of NASA Deep Space Network. Cassini was maneuvered continuously to track the region of Titan's surface where mirror-like (quasi-specular) reflected signals may be observed. The experiments were designed for incidence angles θ close to the Brewster, or polarization, angle of likely surface compositions. Careful measurement of the system noise temperature allowed determination of the absolute power in each polarized echo component and hence their ratio. The polarization ratio, the known observation geometry, and Fresnel reflection theory were then used to determine the dielectric constant ɛ. Three near-equatorial (~ 5 to 15° S) observations on flyby T14 inbound and outbound and on flyby T34 inbound yielded weak but clearly detectable echoes. The echoes were intermittent along the ground track, indicating mostly rough terrain occasionally interrupted by patches of relatively flat areas. For the two observations on T14, polarization ratio measurements for two localized but widely separated surface regions (~ 15° S, ~ 14 and 140° W) conducted at angles θ ~ 56° and 64°, close to the Brewster angle for ices, imply ɛ ~ 1.6 for both regions, suggesting liquid hydrocarbons although alternative interpretations are possible (Marouf et al., 2006 Fall AGU, P11A- 07). In sharp contrast, a single high latitude (~81-86° S, ~ 45-155° W) observation on T27 inbound yielded much stronger surface echoes that lasted for almost the full duration of the experiment

  15. Ocean wave diffraction in near-shore regions observed by Synthetic Aperture Radar

    2006-01-01

    Observation and analysis of ocean wave diffraction in near-shore and near-island region was performed with Synthetic Aperture Radar (SAR) data, using an optimized retrieval method named parameterized first-guess spectrum retrieval method. The results retrieved from ERS-SAR and ENVISAT-ASAR images showed that, in the region sheltered by land jut, the energy of long waves is reduced by 10%-20% and that the propagation direction of long waves is changed due to the effect of topography. In the shadow zone behind the island, ocean wave can propagate along the seashore instead of perpendicular to the coastline, as shown by SAR images.

  16. A flare observed in coronal, transition region, and helium I 10830 Å emissions

    Zeng, Zhicheng; Cao, Wenda [Center for Solar-Terrestrial Research, New Jersey Institute of Technology, 323 Martin Luther King Boulevard, Newark, NJ 07102 (United States); Qiu, Jiong [Department of Physics, Montana State University, Bozeman, MT 59717-3840 (United States); Judge, Philip G. [High Altitude Observatory, National Center for Atmospheric Research, Boulder, CO 80307-3000 (United States)

    2014-10-01

    On 2012 June 17, we observed the evolution of a C-class flare associated with the eruption of a filament near a large sunspot in the active region NOAA 11504. We obtained high spatial resolution filtergrams using the 1.6 m New Solar Telescope at the Big Bear Solar Observatory in broadband TiO at 706 nm (bandpass: 10 Å) and He I 10830 Å narrow band (bandpass: 0.5 Å, centered 0.25 Å to the blue). We analyze the spatio-temporal behavior of the He I 10830 Å data, which were obtained over a 90''×90'' field of view with a cadence of 10 s. We also analyze simultaneous data from the Atmospheric Imaging Assembly and Extreme Ultraviolet Variability Experiment instruments on board the Solar Dynamics Observatory spacecraft, and data from the Reuven Ramaty High Energy Solar Spectroscopic Imager and GOES spacecrafts. Non-thermal effects are ignored in this analysis. Several quantitative aspects of the data, as well as models derived using the '0D' enthalpy-based thermal evolution of loops model code, indicate that the triplet states of the 10830 Å multiplet are populated by photoionization of chromospheric plasma followed by radiative recombination. Surprisingly, the He II 304 Å line is reasonably well matched by standard emission measure calculations, along with the C IV emission which dominates the Atmosphere Imaging Assembly 1600 Å channel during flares. This work lends support to some of our previous work combining X-ray, EUV, and UV data of flares to build models of energy transport from corona to chromosphere.

  17. A TRANSITION REGION EXPLOSIVE EVENT OBSERVED IN He II WITH THE MOSES SOUNDING ROCKET

    Transition region explosive events (EEs) have been observed with slit spectrographs since at least 1975, most commonly in lines of C IV (1548 A, 1550 A) and Si IV (1393 A, 1402 A). We report what we believe to be the first observation of a transition region EE in He II 304 A. With the Multi-Order Solar EUV Spectrograph (MOSES) sounding rocket, a novel slitless imaging spectrograph, we are able to see the spatial structure of the event. We observe a bright core expelling two jets that are distinctly non-collinear, in directions that are not anti-parallel. The jets have sky-plane velocities of order 75 km s-1 and line-of-sight velocities of +75 km s-1 (blue) and -30 km s-1 (red). The core is a region of high non-thermal Doppler broadening, characteristic of EEs, with maximal broadening 380 km s-1 FWHM. It is possible to resolve the core broadening into red and blue line-of-sight components of maximum Doppler velocities +160 km s-1 and -220 km s-1. The event lasts more than 150 s. Its properties correspond to the larger, long-lived, and more energetic EEs observed in other wavelengths.

  18. Spitzer observations of extragalactic H II regions - III. NGC 6822 and the hot star, H II region connection

    Rubin, Robert H.; Simpson, Janet P.; Colgan, Sean W. J.; Dufour, Reginald J.; Kader, Justin; McNabb, Ian A.; Pauldrach, Adalbert W. A.; Weber, Johann A.

    2016-06-01

    Using the short-high module of the Infrared Spectrograph on the Spitzer Space Telescope, we have measured the [S IV] 10.51, [Ne II] 12.81, [Ne III] 15.56, and [S III] 18.71-μm emission lines in nine H II regions in the dwarf irregular galaxy NGC 6822. These lines arise from the dominant ionization states of the elements neon (Ne++, Ne+) and sulphur (S3+, S++), thereby allowing an analysis of the neon to sulphur abundance ratio as well as the ionic abundance ratios Ne+/Ne++ and S3+/S++. By extending our studies of H II regions in M83 and M33 to the lower metallicity NGC 6822, we increase the reliability of the estimated Ne/S ratio. We find that the Ne/S ratio appears to be fairly universal, with not much variation about the ratio found for NGC 6822: the median (average) Ne/S ratio equals 11.6 (12.2±0.8). This value is in contrast to Asplund et al.'s currently best estimated value for the Sun: Ne/S = 6.5. In addition, we continue to test the predicted ionizing spectral energy distributions (SEDs) from various stellar atmosphere models by comparing model nebulae computed with these SEDs as inputs to our observational data, changing just the stellar atmosphere model abundances. Here, we employ a new grid of SEDs computed with different metallicities: solar, 0.4 solar, and 0.1 solar. As expected, these changes to the SED show similar trends to those seen upon changing just the nebular gas metallicities in our plasma simulations: lower metallicity results in higher ionization. This trend agrees with the observations.

  19. Formation of Solar Delta Active Regions:Twist and Writhe of Magnetic Ropes

    Hong-Qi Zhang

    2004-01-01

    We analyze the process of formation of delta configuration in some well-known super active regions based on photospheric vector magnetogram observations. It is found that the magnetic field in the initial developing stage of some delta active regions shows a potential-like configuration in the solar atmosphere,the magnetic shear develops mainly near the magnetic neutral line with magnetic islands of opposite polarities, and the large-scale photospheric twisted field forming gradually later. Some results are obtained: (1) The analysis of magnetic writhe of whole active regions cannot be limited in the strong field of sunspots, because the contribution of the fraction of decayed magnetic field is non-negligible. (2) The magnetic model of kink magnetic ropes, supposed to be generated in the subatmosphere,is not consistent with the evolution of large-scale twisted photospheric transverse magnetic field and not entirely consistent with the relationship with magnetic shear in some delta active regions. (3) The proposition is that the large-scale delta active regions are formed from contribution by small-scale non-potential magnetic flux bundles generated in the subatmosphere.

  20. Different Modes of Turbulence in the Active Regions of the Solar Photosphere

    Kozak, L. V.; Kostik, R. I.; Cheremnykh, O. K.

    In work the range of different methods for the analysis of characteristics of turbulent processes in the active regions of the solar photosphere has been used. The changes of fluctuations distribution function and its moments were analyzed, spectral analysis was carried out.It was found out from the observations of active region carried out with the 70-cm vacuum tower telescope VTT in Isanie (Tenerife Island, Spain) that the turbulent processes in the sun photosphere are characterized by two different spectra of turbulence. The first one of them is well known Kolmohorov spectrum, which describes the plasma with zero mean magnetic field. The second one is the Kraichnan spectrum with a different from zero mean magnetic field. Transition from one spectrum type to another one occurs at scale of 3 Mm.We have to note that the scale 3 Mm corresponds to one of mesogranulation and testifies about non-zero mean magnetic fields for the consideration of regions exceeding the granulation in active regions of the photosphere. Besides, this clears the possibility of appearance of selforganizing magnetic plasma structures such as spots, active regions and complexes of activity.

  1. The study of a spatial relationship between the Equatorial coronal hole and the Active region

    Karna, Mahendra; Karna, Nishu

    2016-05-01

    The 11-year solar cycle is characterized by the periodic change in the solar activity like sunspot numbers, coronal holes, active regions, eruptions such as flares and coronal mass ejections. We study the relationship between equatorial coronal holes (ECH) and the active regions (AR) as coronal hole positions and sizes change with the solar cycle. We made a detailed study for two solar maximum: Solar Cycle 23 (1999, 2000, 2001 and 2002) and Solar Cycle 24 (2011, 2012 and 2013). We used publically available Heliophysics Feature Catalogue and NOAA Solar Geophysical data for. Moreover, we used daily Solar Region Summary (SRS) data from SWPC/NOAA website. We examined the position of ECH and AR and noted that during a maximum of 23, the majority of ECH were not near active regions. However, in cycle 24 coronal holes and equatorial holes were more close to each other. Moreover, we noticed the asymmetry in AR migrations towards the lower latitude in both Northern and Southern hemisphere in cycle 23. While, no such notable asymmetrical behavior was observed in a maximum of cycle 24. Our goal is to extend the study with cycle 21 and 22 and examine the correlation between equatorial holes, the active regions, and the flares. This combined study will shed light in determining the distribution of flares.

  2. Rice Crop Monitoring by Earth Observation Data in the Asian Region

    Oyoshi, K.; Sobue, S.; Tomiyama, N.; Okumura, T.; Rakwatin, P.

    2012-12-01

    the soil, physiological crop characteristics, and daily weather such as photosynthetic active radiation, precipitation, wind velocity and humidity. Some of these parameters were acquired by satellite observations and others are by in-situ measurements. Table 1 shows the result of rice yield estimation of the pilot study area. The results were highly consistent with the validation data of in-situ measurements and the accuracy of paddy acreage and rice yield are 98.6% and 81.9%, respectively. The prototype system to estimate rice yield was developed only for the small pilot area. To expand the system to the whole country for national food security and statistics, crop calendar which identifies the timing of planting or harvesting of each area is needed to estimate productivity of rice. The Asian region has a large variety of the crop intensity such as single or double and sometimes triple cropping and the pattern is mostly relies on the water availability. Since crop intensity affects the rice yield, it is imperative for rice yield estimates to identify crop intensity. High revisit frequency of EO data such as MODIS is useful for identifying crop intensity. Spatial distribution of crop intensities over the Thailand were identified by applying spectrum analysis to the historical MODIS data, then, we demonstrated the relationships between crop intensity and productivity in Thailand with provincial level.

  3. Observations of Galactic star-forming regions with the Cosmic Background Imager at 31 GHz

    Demetroullas, Constantinos; Stamadianos, Dimitrios; Harper, Stuart; Cleary, Kieran; Jones, Mike; Pearson, Tim; Readhead, Anthony; Taylor, Angela

    2015-01-01

    Studies of the diffuse Galactic radio emission are interesting both for better understanding the physical conditions in our Galaxy and for minimising the contamination in cosmological measurements. Motivated by this we present Cosmic Background Imager 31 GHz observations of the Galactic regions NGC 6357, NGC 6334, W51 and W40 at $\\sim$4$'$.5 resolution and conduct an investigation of the spectral emission process in the regions at 4$'$.5 and 1$^{\\circ}$ resolution. We find that most of the emission in the regions is due to optically thin free-free. For 2 sub-regions of NGC 6334 and for a sub-region of W51 though, at 4$'$.5 resolution and at 31 GHz we detect less emission than expected from extrapolation of radio data at lower frequencies assuming a spectral index of $-$0.12 for optically thin free-free emission, at 3.3$\\sigma$, 3.7$\\sigma$ and 6.5$\\sigma$ respectively. We also detect excess emission in a sub-region of NCG 6334 at 6.4$\\sigma$, after ruling out any possible contribution from Ultra Compact HII (...

  4. PROBA2/SWAP Observations of the Unusual Activity of AR12192

    Seaton, Daniel B.; West, Matthew J.

    2015-04-01

    AR 12192 was the most productive active region of the present solar cycle in terms of flares, but it exhibited many unusual properties. It announced its presence on 14 October 2014 with an eruption that led to the formation of perhaps the largest post-eruptive loop system seen in the solar corona in solar cycle 24. Later this region produced a series of large M- and X-class flares, most of which were essentially confined flares, not associated with any coronal mass ejection. During its second passage across the solar disk, it was associated with a huge region of open field that was observed extending to heights as great as 3 solar-radii in the EUV, some of the largest heights at which any EUV structure has been observed. We discuss our observations of this region with the SWAP EUV imager on board the PROBA2 spacecraft and the implications of the many unusual events and structures associated with this region on our understanding of the mechanisms, such as magnetic reconnection, that drive coronal dynamics, in particular those involved in the onset of flares and eruptions.

  5. Dusty origin of the Broad Line Region in active galaxies

    Czerny, Bozena; Kaluzny, Janusz; Maity, Ishita

    2012-01-01

    The most characteristic property of active galaxies, including quasars, are prominent broad emission lines. I will discuss an interesting possibility that dust is responsible for this phenomenon. The dust is known to be present in quasars in the form of a dusty/molecular torus which results in complexity of the appearance of active galaxies. However, this dust is located further from the black hole than the Broad Line Region. We propose that the dust is present also closer in and it is actually responsible for formation of the broad emission lines. The argument is based on determination of the temperature of the disk atmosphere underlying the Broad Line Region: it is close to 1000 K, independently from the black hole mass and accretion rate of the object. The mechanism is simple and universal but leads to a considerable complexity of the active nucleus surrounding. The understanding the formation of BLR opens a way to use it reliably - in combination with reverberation measurement of its size - as standard ca...

  6. Enhanced activation of motor execution networks using action observation combined with imagination of lower limb movements.

    Villiger, Michael; Estévez, Natalia; Hepp-Reymond, Marie-Claude; Kiper, Daniel; Kollias, Spyros S; Eng, Kynan; Hotz-Boendermaker, Sabina

    2013-01-01

    The combination of first-person observation and motor imagery, i.e. first-person observation of limbs with online motor imagination, is commonly used in interactive 3D computer gaming and in some movie scenes. These scenarios are designed to induce a cognitive process in which a subject imagines himself/herself acting as the agent in the displayed movement situation. Despite the ubiquity of this type of interaction and its therapeutic potential, its relationship to passive observation and imitation during observation has not been directly studied using an interactive paradigm. In the present study we show activation resulting from observation, coupled with online imagination and with online imitation of a goal-directed lower limb movement using functional MRI (fMRI) in a mixed block/event-related design. Healthy volunteers viewed a video (first-person perspective) of a foot kicking a ball. They were instructed to observe-only the action (O), observe and simultaneously imagine performing the action (O-MI), or imitate the action (O-IMIT). We found that when O-MI was compared to O, activation was enhanced in the ventralpremotor cortex bilaterally, left inferior parietal lobule and left insula. The O-MI and O-IMIT conditions shared many activation foci in motor relevant areas as confirmed by conjunction analysis. These results show that (i) combining observation with motor imagery (O-MI) enhances activation compared to observation-only (O) in the relevant foot motor network and in regions responsible for attention, for control of goal-directed movements and for the awareness of causing an action, and (ii) it is possible to extensively activate the motor execution network using O-MI, even in the absence of overt movement. Our results may have implications for the development of novel virtual reality interactions for neurorehabilitation interventions and other applications involving training of motor tasks. PMID:24015241

  7. Enhanced activation of motor execution networks using action observation combined with imagination of lower limb movements.

    Michael Villiger

    Full Text Available The combination of first-person observation and motor imagery, i.e. first-person observation of limbs with online motor imagination, is commonly used in interactive 3D computer gaming and in some movie scenes. These scenarios are designed to induce a cognitive process in which a subject imagines himself/herself acting as the agent in the displayed movement situation. Despite the ubiquity of this type of interaction and its therapeutic potential, its relationship to passive observation and imitation during observation has not been directly studied using an interactive paradigm. In the present study we show activation resulting from observation, coupled with online imagination and with online imitation of a goal-directed lower limb movement using functional MRI (fMRI in a mixed block/event-related design. Healthy volunteers viewed a video (first-person perspective of a foot kicking a ball. They were instructed to observe-only the action (O, observe and simultaneously imagine performing the action (O-MI, or imitate the action (O-IMIT. We found that when O-MI was compared to O, activation was enhanced in the ventralpremotor cortex bilaterally, left inferior parietal lobule and left insula. The O-MI and O-IMIT conditions shared many activation foci in motor relevant areas as confirmed by conjunction analysis. These results show that (i combining observation with motor imagery (O-MI enhances activation compared to observation-only (O in the relevant foot motor network and in regions responsible for attention, for control of goal-directed movements and for the awareness of causing an action, and (ii it is possible to extensively activate the motor execution network using O-MI, even in the absence of overt movement. Our results may have implications for the development of novel virtual reality interactions for neurorehabilitation interventions and other applications involving training of motor tasks.

  8. Implications of Special Regions to Conducting Human Activities on Mars

    Rummel, J. D.; Barlow, N. G.; Beaty, D. W.; Jones, M. A.; Hipkin, V.

    2014-12-01

    A MEPAG Science Analysis Group (SAG) has undertaken an analysis of Special Regions (SR) on Mars—regions where indigenous martian life could exist or where Earth microbes, if introduced, could survive and reproduce. The SR-SAG has considered the impact of SR on future human activities on the martian surface. Human exploration requires access to in-situ resources, some of which may be found in SR. Water and oxygen for ISRU are found in the atmosphere, surface/near-surface ice, hydrated minerals, and perchlorates. Water ice is most abundant at latitudes poleward of ~60 degrees, but polar darkness, cold temperatures, and CO2 degassing present hazards to human operations in these regions. Accessible water is more limited toward the equator, though temperature and solar energy conditions become more favorable. The possible presence of liquid water in Recurring Slope Lineae and active gullies leads to their treatment as SR. Fuel for surface operations and propellants for crew ascent could be manufactured from the martian atmosphere and surface materials, but dust in the atmosphere may clog ISRU equipment and perchlorate is toxic to humans. Power may be produced from solar or nuclear energy. Reliance on solar energy limits operations to the equatorial zone where easily accessible ice resources are limited. Nuclear power allows surface operations at a range of latitudes, but waste heat could convert some non-SR into SR. Radiation shielding is necessary for long-term human operations on Mars and could be obtained by deposition of regolith or by water storage in tanks or as ice around habitats, or the use of underground habitats. SR-SAG recognizes that it will be impossible for all human-associated processes and operations to be conducted within entirely closed systems. Protocols need to be established so (1) human missions to Mars will not contaminate SR nor be contaminated by materials from them, and (2) human activities on Mars will avoid converting areas into SR.

  9. Distinct characteristics of asymmetric magnetic reconnections: Observational results from the exhaust region at the dayside magnetopause

    Zhang, Y. C.

    2016-06-01

    Magnetic reconnection plays a key role in the conversion of magnetic energy into the thermal and kinetic energy of plasma. On either side of the diffusion region in space plasma, the conditions for the occurrence of reconnections are usually not symmetric. Previous theoretical studies have predicted that reconnections under asymmetric conditions will bear different features compared with those of symmetric reconnections, and numerical simulations have verified these distinct features. However, to date, the features of asymmetric reconnections have not been thoroughly investigated using in situ observations; thus, some results from theoretical studies and simulations have not been tested with observations sufficiently well. Here, spacecraft observations are used in a statistical investigation of asymmetric magnetic reconnection exhaust at the dayside magnetopause. The resulting observational features are consistent with the theoretical predictions. The results presented here advance our understanding of the development of reconnections under asymmetric conditions.

  10. Galaxy and cluster redshift observations in the Sextans-Leo region

    Redshift observations of 30 clusters in the direction of the Sextans-Leo supercluster candidate are reported. The observations are part of a program which involves mapping the universe's large-scale structure, and include North Galactic Cap Abell clusters, Abell clusters that have only been partially observed, and unmeasured poor Zwicky clusters. Three large superclusters are identified in the region which surround an apparent void that is open on one side towards the galaxy void in Bootes. The minimum dimensions of the void are given, and one of the superclusters is identified based on it resemblance to Coma/A1367. The emptiness of the Bootes void and the void of Bahcall and Soneira (1982) are redefined by the positions determined for five clusters observed in other portions of the northern cap. Additionally, some galaxies appear to be within the bounds of the Sextans-Leo void. 23 refs

  11. FERMI OBSERVATIONS OF TeV-SELECTED ACTIVE GALACTIC NUCLEI

    We report on observations of TeV-selected active galactic nuclei (AGNs) made during the first 5.5 months of observations with the Large Area Telescope (LAT) on-board the Fermi Gamma-ray Space Telescope (Fermi). In total, 96 AGNs were selected for study, each being either (1) a source detected at TeV energies (28 sources) or (2) an object that has been studied with TeV instruments and for which an upper limit has been reported (68 objects). The Fermi observations show clear detections of 38 of these TeV-selected objects, of which 21 are joint GeV-TeV sources, and 29 were not in the third EGRET catalog. For each of the 38 Fermi-detected sources, spectra and light curves are presented. Most can be described with a power law of spectral index harder than 2.0, with a spectral break generally required to accommodate the TeV measurements. Based on an extrapolation of the Fermi spectrum, we identify sources, not previously detected at TeV energies, which are promising targets for TeV instruments. Evidence for systematic evolution of the γ-ray spectrum with redshift is presented and discussed in the context of interaction with the extragalactic background light.

  12. Diviner lunar radiometer observations of cold traps in the moon's south polar region

    Paige, D.A.; Siegler, M.A.; Zhang, J.A.; Hayne, P.O.; Foote, E.J.; Bennett, K.A.; Vasavada, A.R.; Greenhagen, B.T.; Schofield, J.T.; McCleese, D.J.; Foote, M.C.; DeJong, E.; Bills, B.G.; Hartford, W.; Murray, B.C.; Allen, C.C.; Snook, K.; Soderblom, L.A.; Calcutt, S.; Taylor, F.W.; Bowles, N.E.; Bandfield, J.L.; Elphic, R.; Ghent, R.; Glotch, T.D.; Wyatt, M.B.; Lucey, P.G.

    2010-01-01

    Diviner Lunar Radiometer Experiment surface-temperature maps reveal the existence of widespread surface and near-surface cryogenic regions that extend beyond the boundaries of persistent shadow. The Lunar Crater Observation and Sensing Satellite (LCROSS) struck one of the coldest of these regions, where subsurface temperatures are estimated to be 38 kelvin. Large areas of the lunar polar regions are currently cold enough to cold-trap water ice as well as a range of both more volatile and less volatile species. The diverse mixture of water and high-volatility compounds detected in the LCROSS ejecta plume is strong evidence for the impact delivery and cold-trapping of volatiles derived from primitive outer solar system bodies.

  13. Using Satellite Measurements to Investigate Regional-scale Chemistry: The Case for Geostationary Observations

    Fishman, Jack; Wozniak, Amy; Creilson, Jack

    2007-01-01

    One of the recommendations of the Decadal Survey that was recently released by the National Academy of Science was that of a geostationary platform from which to obtain trace gas measurements. The use of such a platform is particularly advantageous when applied to understanding the formation of regional air pollution. This study demonstrates the challenges of trying to utilize information from instruments on satellites in low-earth orbit (LEO). We also demonstrate the advantage gained through a simulation that would provide hourly observations. In this case study, we take advantage of the high resolution Level-2 orbital data available from the Ozone Monitoring Instrument (OMI), in conjunction with assimilated stratospheric column ozone fields, to evaluate if meaningful tropospheric ozone information can be obtained on a regional scale. We focus on a period on late June 2005 when a widespread pollution episode enveloped the Houston metropolitan area as well as a large region in southeast Texas.

  14. Sign singularity and flares in solar active region NOAA 11158

    Sorriso-Valvo, Luca; Kazachenko, Maria D; Krucker, Sam; Primavera, Leonardo; Servidio, Sergio; Vecchio, Antonio; Welsch, Brian T; Fisher, George H; Lepreti, Fabio; Carbone, Vincenzo

    2015-01-01

    Solar Active Region NOAA 11158 has hosted a number of strong flares, including one X2.2 event. The complexity of current density and current helicity are studied through cancellation analysis of their sign-singular measure, which features power-law scaling. Spectral analysis is also performed, revealing the presence of two separate scaling ranges with different spectral index. The time evolution of parameters is discussed. Sudden changes of the cancellation exponents at the time of large flares, and the presence of correlation with EUV and X-ray flux, suggest that eruption of large flares can be linked to the small scale properties of the current structures.

  15. Detailed processes accompanying the decay of an active region

    High resolution (better than 1'') magnetograms obtained at the Sacramento Peak Vacuum Tower Telescope were used to study the decay of a small active region. The reduction process allows one to match intensity and magnetic pictures exactly. Some of the main results are: (i) The granulation massages a magnetic pore, probably inducing its fragmentation. The supergranules get rid of the decayed pieces transporting them away from the pore. (ii) Magnetic flux is removed from the photosphere through its submergence. (author). 5 figs., 10 refs

  16. Observations of concentrated generator regions in the nightside magnetosphere by Cluster/FAST conjunctions

    M. Hamrin

    2006-03-01

    Full Text Available Here and in the companion paper, Marghitu et al. (2006, we investigate plausible auroral generator regions in the nightside auroral magnetosphere. In this article we use magnetically conjugate data from the Cluster and the FAST satellites during a 3.5-h long event from 19-20 September 2001. Cluster is in the Southern Hemisphere close to apogee, where it probes the plasma sheet and lobe at an altitude of about 18 RE. FAST is below the acceleration region at approximately 0.6 RE. Searching for clear signatures of negative power densities, E·J<0, in the Cluster data we can identify three concentrated generator regions (CGRs during our event. From the magnetically conjugate FAST data we see that the observed generator regions in the Cluster data correlate with auroral precipitation. The downward Poynting flux observed by Cluster, as well as the scale size of the CGRs, are consistent with the electron energy flux and the size of the inverted-V regions observed by FAST. To our knowledge, these are the first in-situ observations of the crossing of an auroral generator region. The main contribution to E·J<0 comes from the GSE EyJy. The electric field Ey is weakly negative during most of our entire event and we conclude that the CGRs occur when the duskward current Jy grows large and positive. We find that our observations are consistent with a local southward expansion of the plasma sheet and/or rather complicated, 3-D wavy structures propagating over the Cluster satellites. We find that the plasma is working against the magnetic field, and that kinetic energy is being converted into electromagnetic energy. Some of the energy is transported away as Poynting flux.

  17. Feedback of observed interannual vegetation change: a regional climate model analysis for the West African monsoon

    Klein, Cornelia; Bliefernicht, Jan; Heinzeller, Dominikus; Gessner, Ursula; Klein, Igor; Kunstmann, Harald

    2016-06-01

    West Africa is a hot spot region for land-atmosphere coupling where atmospheric conditions and convective rainfall can strongly depend on surface characteristics. To investigate the effect of natural interannual vegetation changes on the West African monsoon precipitation, we implement satellite-derived dynamical datasets for vegetation fraction (VF), albedo and leaf area index into the Weather Research and Forecasting model. Two sets of 4-member ensembles with dynamic and static land surface description are used to extract vegetation-related changes in the interannual difference between August-September 2009 and 2010. The observed vegetation patterns retain a significant long-term memory of preceding rainfall patterns of at least 2 months. The interannual vegetation changes exhibit the strongest effect on latent heat fluxes and associated surface temperatures. We find a decrease (increase) of rainy hours over regions with higher (lower) VF during the day and the opposite during the night. The probability that maximum precipitation is shifted to nighttime (daytime) over higher (lower) VF is 12 % higher than by chance. We attribute this behaviour to horizontal circulations driven by differential heating. Over more vegetated regions, the divergence of moist air together with lower sensible heat fluxes hinders the initiation of deep convection during the day. During the night, mature convective systems cause an increase in the number of rainy hours over these regions. We identify this feedback in both water- and energy-limited regions of West Africa. The inclusion of observed dynamical surface information improved the spatial distribution of modelled rainfall in the Sahel with respect to observations, illustrating the potential of satellite data as a boundary constraint for atmospheric models.

  18. Structure of a Magnetic Decrease Observed in a Corotating Interaction Region

    Lee, Ensang; Parks, George K.

    2016-02-01

    Magnetic decreases are often observed in various regions of interplanetary space. Many studies are devoted to reveal the physical nature and generation mechanism of the magnetic decreases, but still we do not fully understand magnetic decreases. In this study, we investigate the structure of a magnetic decrease observed in a corotating interaction region using multi-spacecraft measurements. We use three spacecraft, ACE, Cluster, and Wind, which were widely separated in the x- and y-directions in the geocentric solar ecliptic (GSE) coordinates. The boundaries of the magnetic decrease are the same at the three locations and can be identified as tangential discontinuities. A notable feature is that the magnetic decrease has very large dimension, ≳268 R_{E}, along the boundary, which is much larger than the size, ˜6 R_{E}, along the normal direction. This suggests that the magnetic decrease has a shape of a long, thin rod or a wide slab.

  19. Neutral and Ionized Hydrides in Star-forming Regions -- Observations with Herschel/HIFI

    O. Benz, Arnold; Bruderer, Simon; F. van Dishoeck, Ewine;

    2013-01-01

    The cosmic abundance of hydrides depends critically on high-energy UV, X-ray, and particle irradiation. Here we study hydrides in star-forming regions where irradiation by the young stellar object can be substantial, and density and temperature can be much enhanced over interstellar values. Lines...... of OH, CH, NH, SH and their ions OH+, CH+, NH+, SH+, H2O+, and H3O+ were observed in star-forming regions by the HIFI spectrometer onboard the Herschel Space Observatory. Molecular column densities are derived from observed ground-state lines, models, or rotational diagrams. We report here on two...... including emission in the far UV (FUV, 6 -- 13.6 eV) irradiating the outflow walls that separate the outflowing gas and infalling envelope material. We confirm that the effect of FUV in two dimensional models with enlarged irradiated surfaces is clearly noticeable. A molecule that is very sensitive to FUV...

  20. The observation of damage regions produced by neutron irradiation in lithium-doped silicon solar cells.

    Ghosh, S.; Sargent, G. A.

    1972-01-01

    Study regions of lattice disorder produced in lithium-doped float-zone melted n/p-type silicon solar cells by irradiation with monoenergetic neutrons at doses between 10 to the 10th and 10 to the 13th per cu cm. The defect regions were revealed by chemically etching the surface of the solar cells and by observing carbon replicas in an electron microscope. It was found that the defect density increased with increasing irradiation dose and increased lithium content, whereas the average defect diameter was found to decrease. From thermal annealing experiments it was found that in the lithium-doped material the defect structure was stable at temperatures between 300 and 1200 K. This was found to be in contrast to the undoped material where at the lowest doses considerable annealing was observed to occur. These results are discussed in terms of the theoretical predictions and models of defect clusters proposed by Gossick (1959) and Crawford and Cleland (1959).

  1. HEATING SIGNATURES IN THE DISK COUNTERPARTS OF SOLAR SPICULES IN INTERFACE REGION IMAGING SPECTROGRAPH OBSERVATIONS

    We use coordinated observations with the Interface Region Imaging Spectrograph (IRIS) and the Swedish 1 m Solar Telescope to identify the disk counterpart of type II spicules in upper-chromospheric and transition region (TR) diagnostics. These disk counterparts were earlier identified through short-lived asymmetries in chromospheric spectral lines: rapid blue- or red-shifted excursions (RBEs or RREs). We find clear signatures of RBEs and RREs in Mg II h and k, often with excursions of the central h3 and k3 absorption features in concert with asymmetries in co-temporal and co-spatial Hα spectral profiles. We find spectral signatures for RBEs and RREs in C II 1335 and 1336 Å and Si IV 1394 and 1403 Å spectral lines and interpret this as a sign that type II spicules are heated to at least TR temperatures, supporting other recent work. These C II and Si IV spectral signals are weaker for a smaller network region than for more extended network regions in our data. A number of bright features around extended network regions observed in IRIS slit-jaw imagery SJI 1330 and 1400, recently identified as network jets, can be clearly connected to Hα RBEs and/or RREs in our coordinated data. We speculate that at least part of the diffuse halo around network regions in the IRIS SJI 1330 and 1400 images can be attributed to type II spicules with insufficient opacity in the C II and Si IV lines to stand out as single features in these passbands

  2. RESULTS OF OZONE OBSERVATION FROM THE EQUATORIAL REGION TO ANTARCTICA IN 1987

    マツバラ, コウジ; ドイ, モトヒサ; ウエクボ, テツロウ; オカダ, ケンジ; アオキ, シュンジ; カワグチ, サダオ; Kouji, Matsubara; Motohisa, DOI; Tetsuro, UEKUBO; Kenji, Okada; Shuhji, AOKI; Sadao, KAWAGUCHI

    1991-01-01

    The first total ozone observation and vertical ozone sounding on board the research vessel 'SHIRASE' from the equatorial region to Antarctica was carried out in 1987 by meteorological members of the 29th JARE (Japanese Antarctic Research Expedition) team. Total ozone and vertical ozone profile were measured by Brewer ozone spectrophotometer and ozonesondes, respectively. The detailed latitudinal distribution of total ozone amount and height-latitude distributions of ozone concentration, tempe...

  3. Radar observations of artificial E-region field-aligned irregularities

    E. Nossa; D. L. Hysell; Fallen, C. T.; B. J. Watkins

    2009-01-01

    Artificial E region field aligned plasma density irregularities (FAIs) were generated using HAARP in four different experimental modes and observed with a coherent scatter radar imager located 450 km to the southwest where it could detect field-aligned backscatter. The experiments were conducted in July of 2008, during the Polar Aeronomy and Radio Science Summer School (PARS), during quiet conditions in the daytime when the E layer was dense and absorption was modest. Th...

  4. Precipitable Water Vapor Estimates in the Australian Region from Ground-Based GPS Observations

    Suelynn Choy; Chuan-Sheng Wang; Ta-Kang Yeh; John Dawson; Minghai Jia; Yuriy Kuleshov

    2015-01-01

    We present a comparison of atmospheric precipitable water vapor (PWV) derived from ground-based global positioning system (GPS) receiver with traditional radiosonde measurement and very long baseline interferometry (VLBI) technique for a five-year period (2008–2012) using Australian GPS stations. These stations were selectively chosen to provide a representative regional distribution of sites while ensuring conventional meteorological observations were available. Good agreement of PWV estimat...

  5. Characteristics of quasi-static potential structures observed in the auroral return current region by Cluster

    G. T. Marklund; Karlsson, T.; Figueiredo, S.; Johansson, T.; Lindqvist, P.-A.; André, M.; S. Buchert; Kistler, L. M.; A. Fazakerley

    2004-01-01

    Temporal and spatial characteristics of intense quasi-static electric fields and associated electric potential structures in the return current region are discussed using Cluster observations at geocentric distances of about 5 Earth radii. Results are presented from four Cluster encounters with such acceleration structures to illustrate common as well as different features of such structures. The electric field structures are characterized by (all values are projected to 100 km altitude) peak...

  6. Observations and Modelling of Microphysical Variability, Aggregation & Sedimentation in Tropical Storm Cirrus Outflow Regions

    M. W. Gallagher; P. J. Connolly; Crawford, I.; Heymsfield, A.; Bower, K. N.; T. W. Choularton; Allen, G.; Flynn, M. J.; G. Vaughan; Hacker, J

    2012-01-01

    Aircraft measurements of the microphysics of a tropical convective anvil (at temperatures ~−60 °C) forming above the Hector storm, over the Tiwi Islands, Northern Australia, have been conducted with a view to determining ice crystal aggregation efficiencies from in situ measurements. The observed microphysics have been compared to an explicit bin-microphysical model of the anvil region, which includes crystal growth by vapour diffusion and aggregation and the process o...

  7. Regional scale variations of atmospheric CO2 and CH4 from satellite observation

    To identify the sources, sinks and changes of atmospheric CO2 and CH4, this study investigates the spatio-temporal changes of atmospheric CO2 and CH4 concentration on the regional scale by the satellite observations. In this paper, choosing the land region of China as the study area, we investigate the spatio-temporal changes of atmospheric CO2 and CH4 concentrations using the data of the CO2 dry air mixing ratio (XCO2), and the CH4 dry air mixing ratio (XCH4), retrieved by the Greenhouse Gases Observing Satellite (GOSAT) from Jan. 2010 to Dec. 2012. The results show that (1) both XCO2 and XCH4 show higher concentrations in southeastern regions than that in the northwestern, and tend to yearly increasing from 2010 to 2013; (2) XCO2 shows obvious seasonal change with higher values in the spring than that in summer. The seasonal peak-to-peak amplitude is 8 ppm and the annual growth is about 2 ppm. XCH4, however, does not show a seasonal change; (3) With regard to different land-use backgrounds, XCO2 shows larger concentrations over the areas of urban agglomeration than that over the grasslands and deserts, and XCH4 shows lower concentrations over deserts than that over the Yangtze River Delta region and Sichuan Basin

  8. New radio observations of anomalous microwave emission in the HII region RCW175

    Battistelli, E S; Cruciani, A; de Bernardis, P; Genova-Santos, R; Masi, S; Naldi, A; Paladini, R; Piacentini, F; Tibbs, C T; Verstraete, L; Ysard, N

    2015-01-01

    We have observed the HII region RCW175 with the 64m Parkes telescope at 8.4GHz and 13.5GHz in total intensity, and at 21.5GHz in both total intensity and polarization. High angular resolution, high sensitivity, and polarization capability enable us to perform a detailed study of the different constituents of the HII region. For the first time, we resolve three distinct regions at microwave frequencies, two of which are part of the same annular diffuse structure. Our observations enable us to confirm the presence of anomalous microwave emission (AME) from RCW175. Fitting the integrated flux density across the entire region with the currently available spinning dust models, using physically motivated assumptions, indicates the presence of at least two spinning dust components: a warm component with a relatively large hydrogen number density n_H=26.3/cm^3 and a cold component with a hydrogen number density of n_H=150/cm^3. The present study is an example highlighting the potential of using high angular-resolutio...

  9. Combined X-Ray and mm-Wave Observations of Radio Quiet Active Galaxies

    Behar, E.

    2016-06-01

    A connection between the X-ray and radio sources in radio quiet active galaxies (AGNs) will be demonstrated. High radio frequency, i.e., mm-wave observations are promising probes of the X-ray emitting inner regions of the accretion disks in radio quiet AGNs. An argument for simultaneous observations in X-rays and in mm waves will be made, in order to promote these as one of the future science goals of X-ray and AGN astronomy in the next decade. Preliminary results from an exploratory campaign with several space and ground based telescopes will be presented.

  10. Realistic Modeling of SDO/AIA-discovered Coronal Fast MHD Wave Trains in Active Regions

    Ofman, Leon; Liu, Wei

    2016-05-01

    High-resolution EUV observations by space telescopes have provided plenty of evidence for coronal MHD waves in active regions. In particular, SDO/AIA discovered quasi-periodic, fast-mode propagating MHD wave trains (QFPs), which can propagate at speeds of ~1000 km/s perpendicular to the magnetic field. Such waves can provide information on the energy release of their associated flares and the magnetized plasma structure of the active regions. Before we can use these waves as tools for coronal seismology, 3D MHD modeling is required for disentangling observational ambiguities and improving the diagnostic accuracy. We present new results of observationally contained models of QFPs using our recently upgraded radiative, thermally conductive, visco-resistive 3D MHD code. The waves are excited by time-depended boundary conditions constrained by the spatial (localized) and quasi-periodic temporal evolution of a C-class flare typically associated with QFPs. We investigate the excitation, propagation, and damping of the waves for a range of key model parameters, such as the background temperature, density, magnetic field structure, and the location of the flaring site within the active region. We synthesize EUV intensities in multiple AIA channels and then obtain the model parameters that best reproduce the properties of observed QFPs. We discuss the implications of our model results for the seismological application of QFPs and for understanding the dynamics of their associated flares.

  11. Measurements of Non-Thermal Line Widths in Solar Active Regions

    Brooks, David H

    2015-01-01

    Spectral line widths are often observed to be larger than can be accounted for by thermal and instrumental broadening alone. This excess broadening is a key observational constraint for both nanoflare and wave dissipation models of coronal heating. Here we present a survey of non-thermal velocities measured in the high temperature loops (1--5MK) often found in the cores of solar active regions. This survey of $\\textit{Hinode}$ Extreme Ultraviolet Imaging Spectrometer (EIS) observations covers 15 non-flaring active regions that span a wide range of solar conditions. We find relatively small non-thermal velocities, with a mean value of 17km s$^{-1}$, and no significant trend with temperature or active region magnetic flux. These measurements appear to be inconsistent with those expected from reconnection jets in the corona, chromospheric evaporation induced by coronal nanoflares, and Alfv\\'en wave turbulence models. Furthermore, because the observed non-thermal widths are generally small their measurements are ...

  12. Region-based active contour with noise and shape priors

    Lecellier, François; Fadili, Jalal; Aubert, Gilles; Revenu, Marinette; Saloux, Eric

    2008-01-01

    In this paper, we propose to combine formally noise and shape priors in region-based active contours. On the one hand, we use the general framework of exponential family as a prior model for noise. On the other hand, translation and scale invariant Legendre moments are considered to incorporate the shape prior (e.g. fidelity to a reference shape). The combination of the two prior terms in the active contour functional yields the final evolution equation whose evolution speed is rigorously derived using shape derivative tools. Experimental results on both synthetic images and real life cardiac echography data clearly demonstrate the robustness to initialization and noise, flexibility and large potential applicability of our segmentation algorithm.

  13. The Arctic Observing Viewer: A Web-mapping Application for U.S. Arctic Observing Activities

    Cody, R. P.; Manley, W. F.; Gaylord, A. G.; Kassin, A.; Villarreal, S.; Barba, M.; Dover, M.; Escarzaga, S. M.; Habermann, T.; Kozimor, J.; Score, R.; Tweedie, C. E.

    2015-12-01

    interoperable resources in this way will help to ensure improved capacities for conducting activities such as assessing the status of arctic observing efforts, optimizing logistic operations, and for quickly accessing external and project-focused web resources for more detailed information and access to scientific data and derived products.

  14. Field-Aligned Electrons in Polar Region Observed by Cluster on 30 September 2001

    The physical process in the Earth's polar region is very complex and still needs to be further studied. Using the data from Cluster satellite measurement, an analysis on field-aligned electrons in the mid-latitude cusp on 30 September 2001 has been performed. The satellite observed a down-flowing electron event in the low-latitude boundary and a sequential up-flowing electron event in the high-latitude boundary of the cusp region. The down-flowing electron had a velocity as high as 500 km/s and a flux of 2.0 × 109 cm−2·s−1. The up-flowing electron had a velocity up to 1200 km/s and a flux of 4.9 × 109 cm−2·s−1. Both the velocity and the flux observed in this event are the maximum values of the up-flowing electrons observed by all satellites to date. The electron is the main contributor for the field-aligned current in this event. The physical mechanism is also discussed. The down-flowing electron in the low-latitude boundary of the cusp region may result from solar wind injecting during the southward IMF, and the up-flowing electrons in the high-latitude boundary of cusp may result from mirroring of the solar wind, or from the ionospheric up-flowing electrons which have been accelerated

  15. Wind observations of low energy particles within a solar wind reconnection region

    K. E. J. Huttunen

    2008-09-01

    Full Text Available We report characteristics of thermal particle observations during the encounter of the Wind satellite with the separatrix and the outflow domains of a reconnection event on 22 July 1999 in the solar wind. During the studied event the electrostatic analyzers on Wind were transmitting three-dimensional electron and proton distributions in a burst mode every 3 s, the spin period of the spacecraft. The event was associated with a magnetic shear angle of 114° and a large guide magnetic field. The observations suggest that Wind crossed the separatrix and outflow regions about a thousand of ion skin depths from the X-line. At the leading separator boundary, a strong proton beam was identified that originated from the direction of the X-line. In the separatrix and the outflow regions, the phase space distributions of thermal electrons displayed field aligned bidirectional anisotropy. During the crossings of the current sheets bounding the outflow region, we identified two adjacent layers in which the dominant thermal electron flows were towards the X-line at the inner edges of the current sheets and away from the X-line at the outer edges. Interestingly, simulation studies and observations in the Earth's magnetosphere have revealed that the electron flows are reversed, consistent with the Hall current system.

  16. The Moon's Permanently Shadowed Regions as Observed by LRO's Lyman Alpha Mapping Project (LAMP) Instrument

    Gladstone, R.; Retherford, K. D.; Stern, S. A.; Egan, A.; Miles, P. F.; Versteeg, M.; Slater, D.; Davis, M. W.; Parker, J.; Kaufmann, D.; Greathouse, T. K.; Steffl, A. J.; Mukherjee, J.; Horvath, D.; Rojas, P.; Feldman, P. D.; Hurley, D. M.; Pryor, W. R.; Hendrix, A. R.

    2011-12-01

    Although of great interest for science and resource utilization, the Moon's permanently shadowed regions (PSRs) near each pole present difficult targets for remote sensing. The Lyman Alpha Mapping Project (LAMP) instrument on the Lunar Reconnaissance Orbiter (LRO) mission is able to map PSRs at far-ultraviolet (FUV) wavelengths using two faint sources of illumination from the night sky: the all-sky Lyα glow produced as interplanetary medium (IPM) H atoms scatter the Sun's Lyα emissions, and the much fainter source from UV-bright stars. Since the reflected light from these two sources produces only a few hundred events per second in the photon-counting LAMP instrument, building maps with useful signal-to-noise (SNR) ratios requires the careful accumulation of the observations from thousands of individual LRO orbits. In this talk we present the latest FUV albedo maps obtained by LAMP of the Moon's southern and northern polar regions. The results show that 1) most PSR regions are darker at all FUV wavelengths, consistent with their surface soils having much larger porosities than non-PSR regions (e.g., P~0.9 or so), and 2) most PSRs are somewhat "redder" (i.e., more reflective at the longer FUV wavelengths) than non-PSR regions, consistent with the presence of ~1-2% water frost at the surface.

  17. Very high latitude F-region irregularities observed by HF-radar backscatter

    In February and March, 1982, a coherent scatter HF radar was operated from Cleary, Alaska to observe 7- to 15-m wavelength F-region plasma irregularities near the poleward edge of the auroral zone and in the polar cap. The radar operated for five days from February 25 to March 1 and produced approximately 700,000 Doppler spectra during that time. Of those nearly 700,000 spectra, approximately 10% showed backscattered power 3 dB or more above the noise level. A ray tracing technique using electron densities determined by the Chatanika incoherent scatter radar was used to predict locations where the HF waves were approximately normal to the magnetic field. If those locations were also to contain small scale electron density structure, then one would expect them to backscatter the HF waves. Several comparisons were made between predicted and observed locations of radiowave backscatter and excellent agreement was obtained. In addition, comparisons of the Doppler velocities observed by the coherent scatter HF radar and those observed by the Chatanika radar showed good agreement, suggesting that the plasma irregularities observed by the HF radar drift with the ambient plasma. In addition, average vector velocities calculated for the entire 5-day period show a flow pattern consistent with polar cap convection models. This again indicates that the irregularities drift with the plasma, as is predicted by a number of theories of F-region plasma irregularities. In the summer of 1983, the research program begun with those measurements will be continued with a steerable phased-array HF radar located at Goose Bay, Labrador, that will view the same ionospheric region as does the Sondre Stromfjord incoherent scatter radar

  18. Geodetic Observations From the Region Surrounding the M 5.2 Mt. Carmel, Illinois Earthquake

    Hamburger, M.; Galgana, G.; Johnson, K.

    2008-12-01

    We present new results from a GPS geodetic network in the southern Illinois Basin, including a post-seismic survey in the aftermath of the M5.2 Mt. Carmel Illinois earthquake. A 56-station regional network at ~30 km spacing in SW Indiana, S Illinois and W Kentucky is augmented by continuous data from IGS, GAMA, and CORS GPS stations. We also present results from a densified, 35-station GPS network (~10 km spacing) in the Fluorspar district of southernmost Illinois, located near near a complex transitional zone between the Wabash Valley and New Madrid seismic zones. The region is traversed by steep-angled, basement-penetrating faults and characterized by moderate (M ~3 to 5.5) earthquakes. The most recent of these events was the April 18, 2008 M 5.2 event, located close to the New Harmony Fault at ~14 km deep near Mt. Carmel, Illinois. We combine data from the regional network with GPS observations from five stations near the epicenter of the April 2008 earthquake. Predictions based on the depth and mechanism of the earthquake suggest horizontal coseismic motions of < 1mm at most network stations. Observed data suggest small, but marginally significant displacements as compared to block motions in the area. Results from the regional network show highly improved position and velocity estimates of these campaign sites relative to previous campaign measurements, with station velocities suggesting systematic northwestward motion of about 0.5-0.7 mm/yr with respect to the Stable North American Reference Frame. We then investigate strain patterns using models to explain tectonic deformation within the Wabash Valley. We use an elastic block modeling approach, supplemented by continuum-based methods to explain variable strain between GPS stations. Block models which assume boundaries along the Cottonwood Grove-Rough Creek Graben (CGRCG) and the WVFS indicate marginal block velocities with possible strike- slip motion along the WVFS, and E-W motions along the CGRCG. We also

  19. High time resolution observations of HF cross-modulation within the D region ionosphere

    Langston, J.; Moore, R. C.

    2013-05-01

    High-frequency cross-modulation is employed to probe the D region ionosphere during HF heating experiments at the High-frequency Active Auroral Research Program (HAARP) observatory. We have adapted Fejer's well-known cross-modulation probing method to determine the extent of ionospheric conductivity modification in the D region ionosphere with high (5 μsec) time resolution. We demonstrate that the method can be used to analyze D region conductivity changes produced by HF heating both during the initial stages of heating and under steady state conditions. The sequence of CW probe pulses used allow the separation of cross-modulation effects that occur as the probe pulse propagates upward and downward through the heated region. We discuss how this probing technique can be applied to benefit ELF/VLF wave generation experiments and ionospheric irregularities experiments at higher altitudes. We demonstrate that large phase changes equivalent to Doppler shift velocities >60 km/s can be imposed on HF waves propagating through the heated D region ionosphere.

  20. E-region decameter-scale plasma waves observed by the dual TIGER HF radars

    Carter, B. A.; Makarevich, R. A.

    2009-01-01

    The dual Tasman International Geospace Environment Radar (TIGER) HF radars regularly observe E-region echoes at sub-auroral magnetic latitudes 58°-60° S including during geomagnetic storms. We present a statistical analysis of E-region backscatter observed in a period of ~2 years (late 2004-2006) by the TIGER Bruny Island and Unwin HF radars, with particular emphasis on storm-time backscatter. It is found that the HF echoes normally form a 300-km-wide band at ranges 225-540 km. In the evening sector during geomagnetic storms, however, the HF echoes form a curved band joining to the F-region band at ~700 km. The curved band lies close to the locations where the geometric aspect angle is zero, implying little to no refraction during geomagnetic storms, which is an opposite result to what has been reported in the past. The echo occurrence, Doppler velocity, and spectral width of the HF echoes are examined in order to determine whether new HF echo types are observed at sub-auroral latitudes, particularly during geomagnetic storms. The datasets of both TIGER radars are found to be dominated by low-velocity echoes. A separate population of storm-time echoes is also identified within the datasets of both radars with most of these echoes showing similar characteristics to the low-velocity echo population. The storm-time backscatter observed by the Bruny Island radar, on the other hand, includes near-range echoes (r<405 km) that exhibit some characteristics of what has been previously termed the High Aspect angle Irregularity Region (HAIR) echoes. We show that these echoes appear to be a storm-time phenomenon and further investigate this population by comparing their Doppler velocity with the simultaneously measured F- and E-region irregularity velocities. It is suggested that the HAIR-like echoes are observed only by HF radars with relatively poor geometric aspect angles when electron density is low and when the electric field is particularly high.

  1. E-region decameter-scale plasma waves observed by the dual TIGER HF radars

    B. A. Carter

    2009-01-01

    Full Text Available The dual Tasman International Geospace Environment Radar (TIGER HF radars regularly observe E-region echoes at sub-auroral magnetic latitudes 58°–60° S including during geomagnetic storms. We present a statistical analysis of E-region backscatter observed in a period of ~2 years (late 2004–2006 by the TIGER Bruny Island and Unwin HF radars, with particular emphasis on storm-time backscatter. It is found that the HF echoes normally form a 300-km-wide band at ranges 225–540 km. In the evening sector during geomagnetic storms, however, the HF echoes form a curved band joining to the F-region band at ~700 km. The curved band lies close to the locations where the geometric aspect angle is zero, implying little to no refraction during geomagnetic storms, which is an opposite result to what has been reported in the past. The echo occurrence, Doppler velocity, and spectral width of the HF echoes are examined in order to determine whether new HF echo types are observed at sub-auroral latitudes, particularly during geomagnetic storms. The datasets of both TIGER radars are found to be dominated by low-velocity echoes. A separate population of storm-time echoes is also identified within the datasets of both radars with most of these echoes showing similar characteristics to the low-velocity echo population. The storm-time backscatter observed by the Bruny Island radar, on the other hand, includes near-range echoes (r<405 km that exhibit some characteristics of what has been previously termed the High Aspect angle Irregularity Region (HAIR echoes. We show that these echoes appear to be a storm-time phenomenon and further investigate this population by comparing their Doppler velocity with the simultaneously measured F- and E-region irregularity velocities. It is suggested that the HAIR-like echoes are observed only by HF radars with relatively poor geometric aspect angles when electron density is low and when the electric field is particularly

  2. Measurements of cloud condensation nuclei activity and droplet activation kinetics of wet processed regional dust samples and minerals

    P. Kumar

    2011-04-01

    Full Text Available This study reports laboratory measurements of particle size distributions, cloud condensation nuclei (CCN activity, and droplet activation kinetics of wet generated aerosols from clays, calcite, quartz, and desert soil samples from Northern Africa, East Asia/China, and Northern America. The dependence of critical supersaturation, sc, on particle dry diameter, Ddry, is used to characterize particle-water interactions and assess the ability of Frenkel-Halsey-Hill adsorption activation theory (FHH-AT and Köhler theory (KT to describe the CCN activity of the considered samples. Regional dust samples produce unimodal size distributions with particle sizes as small as 40 nm, CCN activation consistent with KT, and exhibit hygroscopicity similar to inorganic salts. Clays and minerals produce a bimodal size distribution; the CCN activity of the smaller mode is consistent with KT, while the larger mode is less hydrophilic, follows activation by FHH-AT, and displays almost identical CCN activity to dry generated dust. Ion Chromatography (IC analysis performed on regional dust samples indicates a soluble fraction that cannot explain the CCN activity of dry or wet generated dust. A mass balance and hygroscopicity closure suggests that the small amount of ions (of low solubility compounds like calcite present in the dry dust dissolve in the aqueous suspension during the wet generation process and give rise to the observed small hygroscopic mode. Overall these results identify an artifact that may question the atmospheric relevance of dust CCN activity studies using the wet generation method. Based on a threshold droplet growth analysis, wet generated mineral aerosols display similar activation kinetics compared to ammonium sulfate calibration aerosol. Finally, a unified CCN activity framework that accounts for concurrent effects of solute and adsorption is developed to describe the CCN activity of aged or hygroscopic dusts.

  3. Photospheric electric current and transition region brightness within an active region

    Distributions of vertical electric current density (Jsub(z)) calculated from vector measurements of the photospheric magnetic field are compared with ultraviolet spectroheliograms to investigate whether resistive heating is an important source of enhanced emission in the transition region. The photospheric magnetic fields in Active Region 2372 were measured on 6 and 7 April, 1980 with the MSFC vector magnetograph; ultraviolet wavelength spectroheliograms (Lα and Nv 1239 A) were obtained with the UVSP experiment aboard the Solar Maximum Mission satellite. Spatial registration of the Jsub(z) (5 arc sec resolution) and UV (3 arc sec resolution) maps indicates that the maximum current density is cospatial with a minor but persistent UV enhancement, but there is little detected current associated with other nearby bright areas. We conclude that although resistive heating may be important in the transition region, the currents responsible for the heating are largely unresolved in our measurements and have no simple correlation with the residual current measured on 5 arc sec scales. (orig.)

  4. The Arctic Observing Viewer: A Web-mapping Application for U.S. Arctic Observing Activities

    Kassin, A.; Gaylord, A. G.; Manley, W. F.; Villarreal, S.; Tweedie, C. E.; Cody, R. P.; Copenhaver, W.; Dover, M.; Score, R.; Habermann, T.

    2014-12-01

    way will help to ensure improved capacities for conducting activities such as assessing the status of arctic observing efforts, optimizing logistic operations, and for quickly accessing external and project-focused web resources for more detailed information and data.

  5. The Location of ICT activities in EU regions. Implications for regional policies

    Salvador Barrios

    2008-11-01

    Full Text Available The location of ICT producing industries does matter for global competitivenessand long-run growth potential. For instance, the differing contribution ofICT to economic growth between the US and the EU is often mentioned as one of themain cause explaining the diverging growth performance of these two areas since themid-1990s. In turn, since the mid-1990s, countries with especially dynamic economicgrowth have tended to be highly specialized in ICT-producing and ICT-using industries,see van Ark and Inkaar (2005. More generally, ICT producing sectors, tendto promote technological change and innovative capability which are seen to be at thecore of economic growth and competitiveness. When considering the EU economy,ICT industries appear to be concentrated in a limited number of regions, see Koski etal. (2002 for empirical evidence. Afirst objective of the present paper is to documentthe location of ICT producing industries in European regions in order to map existingEU clusters as well as to analyze recent changes in these industries using recent dataon employment and firm location, especially in relation to the EU enlargement thathas taken place in May 2004. The location of the ICT-producing sectors is not the endof the story however. A crucial aspect concerns the nature of activities that are beingundertaken in different regions. Importantly, ICT industries do have different characteristicsin terms of human capital, skill requirement, and knowledge content. In particular,because of the positive association between human capital, knowledge andlong-run growth, it is important to analyze to what extent EU regional ICT clustersdiffer in according to these characteristics. The second question addressed in the paperconcerns the nature of ICT activities undertaken in EU regions. Finally, the paperprovides econometric estimates of the location of firms in ICT industries across EUregions. The paper considers more specifically the case of multinationals

  6. Analysis on Correlations between Subsurface Kinetic Helicity and Photospheric Current Helicity in Active Regions

    Gao, Yu; Zhang, Hongqi

    2012-01-01

    An investigation on correlations between photospheric current helicity and subsur- face kinetic helicity is carried out by analyzing vector magnetograms and subsurface velocities for two rapidly developing active regions. The vector magnetograms are from the SDO/HMI (Solar Dynamics Observatory / Helioseismic and Magnetic Im- ager) observed Stokes parameters, and the subsurface velocity is from time-distance data-analysis pipeline using HMI Dopplergrams. Over a span of several days, the evo- lution of the weighted current helicity shows a tendency similar to that of the weighted subsurface kinetic helicity, attaining a correlation coefficient above 0.60 for both ac- tive regions. Additionally, there seems to be a phase lag between the evolutions of the unweighted current and subsurface kinetic helicities for one of the active regions. The good correlation between these two helicities indicate that there is some intrinsic con- nection between the interior dynamics and photospheric magnetic twistedness inside ac...

  7. The temperature structure and pressure balance of magnetic loops in active regions. [in solar atmosphere

    Foukal, P.

    1975-01-01

    EUV observations show many active region loops in lines formed at temperatures between 10,000 and 2,000,000 K. The brightest loops are associated with flux tubes leading to the umbrae of sunspots. It is shown that the high visibility of certain loops in transition region lines is due principally to a sharp radial decrease of temperature to chromospheric values toward the loop axis. The plasma density of these cool loops is not significantly greater than in the hot gas immediately surrounding it. Consequently, the internal gas pressure of the cool material is clearly lower. The hot material immediately surrounding the cool loops is generally denser than the external corona by a factor 3-4. When the active region is examined in coronal lines, this hot high pressure plasma shows up as loops that are generally parallel to the cool loops but significantly displaced laterally.

  8. Neutral and ionized hydrides in star-forming regions. Observations with Herschel/HIFI.

    Benz, Arnold O; Bruderer, Simon; van Dishoeck, Ewine F; Stäuber, Pascal; Wampfler, Susanne F

    2013-10-01

    The cosmic abundance of hydrides depends critically on high-energy UV, X-ray, and particle irradiation. Here we study hydrides in star-forming regions where irradiation by the young stellar object can be substantial, and density and temperature can be much enhanced over interstellar values. Lines of OH, CH, NH, and SH and their ions OH(+), CH(+), NH(+), SH(+), H2O(+), and H3O(+) were observed in star-forming regions by the HIFI spectrometer onboard the Herschel Space Observatory. Molecular column densities are derived from observed ground-state lines, models, or rotational diagrams. We report here on two prototypical high-mass regions, AFGL 2591 and W3 IRS5, and compare them to chemical calculations by making assumptions on the high-energy irradiation. A model assuming no ionizing protostellar emission is compared with (i) a model assuming strong protostellar X-ray emission and (ii) a two-dimensional (2D) model including emission in the far UV (FUV, 6-13.6 eV), irradiating the outflow walls that separate the outflowing gas and infalling envelope material. We confirm that the effect of FUV in two-dimensional models with enlarged irradiated surfaces is clearly noticeable. A molecule that is very sensitive to FUV irradiation is CH(+), enhanced in abundance by more than 5 orders of magnitude. The HIFI observations of CH(+) lines agree with the two-dimensional FUV model by Bruderer et al., which computes abundances, non-LTE excitation, and line radiative transfer.20 It is concluded that CH(+) is a good FUV tracer in star-forming regions. The effect of potential X-ray irradiation is not excluded but cannot be demonstrated by the present data. PMID:23862691

  9. Regional and landscape-scale variability of Landsat-observed vegetation dynamics in northwest Siberian tundra

    Widespread increases in Arctic tundra productivity have been documented for decades using coarse-scale satellite observations, but finer-scale observations indicate that changes have been very uneven, with a high degree of landscape- and regional-scale heterogeneity. Here we analyze time-series of the Normalized Difference Vegetation Index (NDVI) observed by Landsat (1984–2012), to assess landscape- and regional-scale variability of tundra vegetation dynamics in the northwest Siberian Low Arctic, a little-studied region with varied soils, landscape histories, and permafrost attributes. We also estimate spatio-temporal rates of land-cover change associated with expansion of tall alder (Alnus) shrublands, by integrating Landsat time-series with very-high-resolution imagery dating to the mid-1960s. We compiled Landsat time-series for eleven widely-distributed landscapes, and performed linear regression of NDVI values on a per-pixel basis. We found positive net NDVI trends (‘greening’) in nine of eleven landscapes. Net greening occurred in alder shrublands in all landscapes, and strong greening tended to correspond to shrublands that developed since the 1960s. Much of the spatial variability of greening within landscapes was linked to landscape physiography and permafrost attributes, while between-landscape variability largely corresponded to differences in surficial geology. We conclude that continued increases in tundra productivity in the region are likely in upland tundra landscapes with fine-textured, cryoturbated soils; these areas currently tend to support discontinuous vegetation cover, but are highly susceptible to rapid increases in vegetation cover, as well as land-cover changes associated with the development of tall shrublands. (paper)

  10. InSAR observations of active volcanoes in Latin America

    Morales Rivera, A. M.; Chaussard, E.; Amelung, F.

    2012-12-01

    Over the last decade satellite-based interferometric synthetic aperture radar (InSAR) has developed into a well-known technique to gauge the status of active volcanoes. The InSAR technique can detect the ascent of magma to shallow levels of the volcanic plumbing system because new arriving magma pressurizes the system. This is likely associated with the inflation of the volcanic edifice and the surroundings. Although the potential of InSAR to detect magma migration is well known, the principal limitation was that only for few volcanoes frequent observations were acquired. The ALOS-1 satellite of the Japanese Aerospace Exploration Agency (JAXA) acquired a global L-band data set of 15-20 acquisitions during 2006-2011. Here we use ALOS InSAR and Small Baseline (SB) time-series methods for a ground deformation survey of Latin America with emphasis on the northern Andes. We present time-dependent ground deformation data for the volcanoes in Colombia, Ecuador and Peru and interpret the observations in terms of the dynamics of the volcanic systems.

  11. On the Area Expansion of Magnetic Flux-Tubes in Solar Active Regions

    Dudik, Jaroslav; Cirtain, Jonathan W

    2014-01-01

    We calculated the 3D distribution of the area expansion factors in a potential magnetic field extrapolated from the high-resolution \\textit{Hinode}/SOT magnetogram of a quiescent active region NOAA 11482. Retaining only closed loops within the computational box, we show that the distribution of area expansion factors show significant structure. Loop-like structures characterized by locally lower values of the expansion factor are embedded in a smooth background. These loop-like flux-tubes have squashed cross-sections and expand with height. The distribution of the expansion factors show overall increase with height, allowing an active region core characterized by low values of the expansion factor to be distinguished. The area expansion factors obtained from extrapolation of the SOT magnetogram are compared to those obtained from an approximation of the observed magnetogram by a series of 134 submerged charges. This approximation retains the general flux distribution in the observed magnetogram, but removes t...

  12. Observation of energetic radiation associated with winter thunderstorm activity

    The dose rate of the gamma-rays increases in association with the activities of the thunderstorm. They were observed on the ground in the winter season of Japan. To investigate the time profile of the radiations during the winter thunderstorms, the radiation detectors were prepared which consist of the long proportional counters. These detectors have different characteristics of the response for the energy of the incident particles by mounting different thick shielding covers. Those results were compared with the results measured at the same time by the environmental radiation monitors set up around a nuclear facility. Electric field was also measured by using a field mill. As a result, the following two types of the radiation enhancements have been found during the winter thunderstorm activities; the gradual variation of photon intensity with energy of a few MeV, and the burst type of the radiation that is attributed to the injection of high energy photons with the energy over 10 MeV. (author)

  13. Comparing regional modeling (CHIMERE) and satellite observations of aerosols (PARASOL): Methodology and case study over Mexico

    Stromatas, Stavros

    2010-05-01

    S. Stromatas (1), S. Turquety (1), H. Chepfer (1), L. Menut (1), B. Bessagnet (2), JC Pere (2), D. Tanré (3) . (1) Laboratoire de Météorologie Dynamique, CNRS/IPSL, École Polytechnique, 91128 Palaiseau Cedex, France, (2) INERIS, Institut National de l'Environnement Industriel et des Risques, Parc technologique ALATA, 60550 Verneuil en Halatte, FRANCE, (3) Laboratoire d'Optique Atmosphérique/CNRS Univ. des Sciences et Tech. de Lille, 59650 - Villeneuve d'Ascq, France. Atmospheric suspended particles (aerosols) have significant radiative and environmental impacts, affecting human health, visibility and climate. Therefore, they are regulated by air quality standards worldwide, and monitored by regional observation networks. Satellite observations vastly improve the horizontal and temporal coverage, providing daily distributions. Aerosols are currently estimated using aerosol optical depth (AOD) retrievals, a quantitative measure of the extinction of solar radiation by aerosol scattering and absorption between the point of observation and the top of the atmosphere. Even though remarkable progresses in aerosol modeling by chemistry-transport models (CTM) and measurement experiments have been made in recent years, there is still a significant divergence between the modeled and observed results. However, AOD retrievals from satellites remains a highly challenging task mostly because it depends on a variety of different parameters such as cloud contamination, surface reflectance contributions and a priori assumptions on aerosol types, each one of them incorporating its own difficulties. Therefore, comparisons between CTM and observations are often difficult to interpret. In this presentation, we will discuss comparisons between regional modeling (CHIMERE CTM) over Mexico and satellite observations obtained by the POLDER instrument embarked on PARASOL micro-satellite. After a comparison of the model AOD with the retrieved L2 AOD, we will present an alternative

  14. Horizontal flows concurrent with an X2.2 flare in active region NOAA 11158

    Beauregard, Laurent; Verma, Meetu; Denker, Carsten

    2012-01-01

    Horizontal proper motions were measured with local correlation tracking (LCT) techniques in active region NOAA 11158 on 2011 February 15 at a time when a major (X2.2) solar flare occurred. The measurements are based on continuum images and magnetograms of the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory. The observed shear flows along the polarity inversion line were rather weak (a few 100 m/s). The counter-streaming region shifted toward the north after the flare....

  15. Analysis on Correlations between Subsurface Kinetic Helicity and Photospheric Current Helicity in Active Regions

    Gao, Yu; Zhao, Junwei; Zhang, Hongqi

    2012-01-01

    An investigation on correlations between photospheric current helicity and subsur- face kinetic helicity is carried out by analyzing vector magnetograms and subsurface velocities for two rapidly developing active regions. The vector magnetograms are from the SDO/HMI (Solar Dynamics Observatory / Helioseismic and Magnetic Im- ager) observed Stokes parameters, and the subsurface velocity is from time-distance data-analysis pipeline using HMI Dopplergrams. Over a span of several days, the evo- l...

  16. Magnetic Systems Triggering the M6.6-class Solar Flare in NOAA Active Region 11158

    Toriumi, Shin; Bamba, Yumi; Kusano, Kanya; Imada, Shinsuke; Inoue, Satoshi

    2013-01-01

    We report a detailed event analysis on the M6.6-class flare in the active region (AR) NOAA 11158 on 2011 February 13. AR 11158, which consisted of two major emerging bipoles, showed prominent activities including one X- and several M-class flares. In order to investigate the magnetic structures related to the M6.6 event, particularly the formation process of a flare-triggering magnetic region, we analyzed multiple spacecraft observations and numerical results of a flare simulation. We observed that, in the center of this quadrupolar AR, a highly sheared polarity inversion line (PIL) was formed through proper motions of the major magnetic elements, which built a sheared coronal arcade lying over the PIL. The observations lend support to the interpretation that the target flare was triggered by a localized magnetic region that had an intrusive structure, namely a positive polarity penetrating into a negative counterpart. The geometrical relationship between the sheared coronal arcade and the triggering region w...

  17. Magnetic Flux Transport and the Long-Term Evolution of Solar Active Regions

    Ugarte-Urra, Ignacio; Warren, Harry P; Hathaway, David H

    2015-01-01

    With multiple vantage points around the Sun, STEREO and SDO imaging observations provide a unique opportunity to view the solar surface continuously. We use He II 304 A data from these observatories to isolate and track ten active regions and study their long-term evolution. We find that active regions typically follow a standard pattern of emergence over several days followed by a slower decay that is proportional in time to the peak intensity in the region. Since STEREO does not make direct observations of the magnetic field, we employ a flux-luminosity relationship to infer the total unsigned magnetic flux evolution. To investigate this magnetic flux decay over several rotations we use a surface flux transport model, the Advective Flux Transport (AFT) model, that simulates convective flows using a time-varying velocity field and find that the model provides realistic predictions when information about the active region's magnetic field strength and distribution at peak flux is available. Finally, we illust...

  18. Hydrogen over helium enhancement in successive solar flare particle events from the same active region

    Briggs, P. R.; Armstrong, T. P.; Krimigis, S. M.

    1979-01-01

    An analysis of all of the identified solar-flare-associated energetic particle events in the 1972-1975 period observed with instruments aboard the IMP 7 and IMP 8 satellites has revealed at least eight occasions when more than one particle-producing flare occurred within the same McMath active plage region during its transit of the visible solar disk. A strong tendency for second flares to produce hydrogen over helium (p/alpha) enhanced energetic particle fluxes when compared with the first flare in the 1.8-10.0 MeV per nucleon range emerged in these multiflare regions. The p/alpha enhancement is apparently transient, and for flares separated by at least about 100 hours the p/alpha ratio tends toward its preflare value. It is suggested that the substrate plasma in an active region may be enriched prior to a flare in elements heavier than hydrogen and the composition may not be significantly altered during subsequent acceleration, escape, and propagation. Thus, the preflare history of the active region must be added to the list of factors influencing observed solar-particle-event composition.

  19. Magnetic Flux Transport and the Long-term Evolution of Solar Active Regions

    Ugarte-Urra, Ignacio; Upton, Lisa; Warren, Harry P.; Hathaway, David H.

    2015-12-01

    With multiple vantage points around the Sun, Solar Terrestrial Relations Observatory (STEREO) and Solar Dynamics Observatory imaging observations provide a unique opportunity to view the solar surface continuously. We use He ii 304 Å data from these observatories to isolate and track ten active regions and study their long-term evolution. We find that active regions typically follow a standard pattern of emergence over several days followed by a slower decay that is proportional in time to the peak intensity in the region. Since STEREO does not make direct observations of the magnetic field, we employ a flux-luminosity relationship to infer the total unsigned magnetic flux evolution. To investigate this magnetic flux decay over several rotations we use a surface flux transport model, the Advective Flux Transport model, that simulates convective flows using a time-varying velocity field and find that the model provides realistic predictions when information about the active region's magnetic field strength and distribution at peak flux is available. Finally, we illustrate how 304 Å images can be used as a proxy for magnetic flux measurements when magnetic field data is not accessible.

  20. Neutral and Ionized Hydrides in Star-forming Regions -- Observations with Herschel/HIFI

    Benz, Arnold O; van Dishoeck, Ewine F; Staeuber, Pascal; Wampfler, Susanne F

    2013-01-01

    The cosmic abundance of hydrides depends critically on high-energy UV, X-ray, and particle irradiation. Here we study hydrides in star-forming regions where irradiation by the young stellar object can be substantial, and density and temperature can be much enhanced over interstellar values. Lines of OH, CH, NH, SH and their ions OH+, CH+, NH+, SH+, H2O+, and H3O+ were observed in star-forming regions by the HIFI spectrometer onboard the Herschel Space Observatory. Molecular column densities are derived from observed ground-state lines, models, or rotational diagrams. We report here on two prototypical high-mass regions, AFGL 2591 and W3 IRS5, and compare them to chemical calculations making assumptions on the high-energy irradiation. A model assuming no ionizing protostellar emission is compared with (i) a model assuming strong protostellar X-ray emission and (ii) a two-dimensional (2D) model including emission in the far UV (FUV, 6 -- 13.6 eV) irradiating the outflow walls that separate the outflowing gas an...

  1. TRMM observations of latent heat distribution over the Indian summer monsoon region and associated dynamics

    Subrahmanyam, Kandula V.; Kishore Kumar, Karanam

    2016-05-01

    The latent heat released/absorbed in the Earth's atmosphere due to phase change of water molecule plays a vital role in various atmospheric processes. It is now well established that the latent heat released in the clouds is the secondary source of energy for driving the atmosphere, the Sun being the primary. In this context, studies on latent heat released in the atmosphere become important to understand the some of the physical processes taking place in the atmosphere. One of the important implications of latent heat release is its role in driving the circulations on various temporal and spatial scales. Realizing the importance of latent heat released in the clouds, a comprehensive study is carried out to understand its role in driving the mesoscale circulation. As Indian summer monsoon (ISM) serves as natural laboratory for studying the clouds and their microphysics, an attempt is made to explore the latent heat distribution over this region using 13 years of Tropical Rainfall Measuring Mission (TRMM) observations. The observed profiles of latent heating over ISM region showed large spatial and temporal variability in the magnitude thus reflecting the presence of organization of convection on mesoscale. The latent profiles in convective and stratiform regions are segregated to study the differences in their interaction with large-scale environment. Various re-analysis dataset were used to examine the role of latent heating distribution on the mesoscale circulation. The significance of the present study lies in establishing the vertical distribution of latent heating and their impact on the background circulation.

  2. SOFIA/FORCAST Observations of the Arched Filamentary Region in the Galactic Center

    Hankins, Matthew; Lau, Ryan M.; Morris, Mark; Herter, Terry L.

    2016-06-01

    Abstract: We present 19.7, 25.2, 31.5, and 37.1 μm maps of the Thermal Arched Filament region in the Galactic Center taken with the Faint Object Infrared Camera for the SOFIA Telescope (FORCAST) with an angular resolution of 3.2-3.8". We calculate the integrated infrared luminosity of the Arched Filaments and show that they are consistent with being heated by the nearby Arches cluster. Additionally, using our observations, we infer dust temperatures (75 – 90 K) across the Arched Filaments which are remarkably consistent over large spatial scales (∼ 25 pc). We discuss the possible geometric effects needed to recreate this temperature structure. Additionally, we compare the observed morphology of the Arches in the FORCAST maps with the Paschen-α emission in the region to study what fraction of the infrared emission may be coming from dust in the HII region versus the PDR beneath it. Finally, we use Spitzer/IRAC 8 μm data to look for spatial variations in PAH abundance in the rich UV environment of the young (~2-4 Myr) and massive Arches cluster.

  3. Characteristics of Anthropogenic Sulfate and Carbonaceous Aerosols over East Asia: Regional Modeling and Observation

    Yan HUANG; William L. CHAMEIDES; Qian TAN; Robert E. DICKINSON

    2008-01-01

    The authors present spatial and temporal characteristics of anthropogenic sulfate and carbonaceous aerosols over East Asia using a 3-D coupled regional climate-chemistry-aerosol model, and compare the simulation with the limited aerosol observations over the region. The aerosol module consists of SO2, SO42-, hydrophobic and hydrophilic black carbon (BC) and organic carbon compounds (OC), including emission, advections, dry and wet deposition, and chemical production and conversion. The simulated patterns of SO2 are closely tied to its emission rate, with sharp gradients between the highly polluted regions and more rural areas. Chemical conversion (especially in the aqueous phase) and dry deposition remove 60% and 30% of the total SO2 emission, respectively. The SO42- shows less horizontal gradient and seasonality than SO2, with wet deposition (60%) and export (27%) being two major sinks. Carbonaceous aerosols are spatially smoother than sulfur species. The aging process transforms more than 80% of hydrophobic BC and OC to hydrophilic components, which are removed by wet deposition (60%) and export (30%). The simulated spatial and seasonal SO42-, BC and OC aerosol concentrations and total aerosol optical depth are generally consistent with the observations in rural areas over East Asia, with lower bias in simulated OC aerosols, likely due to the underestimation of anthropogenic OC emissions and missing treatment of secondary organic carbon. The results suggest that our model is a useful tool for characterizing the anthropogenic aerosol cycle and for assessing its potential climatic and environmental effects in future studies.

  4. The Counter-kink Rotation of a Non-Hale Active Region

    Fuentes, M C López; Mandrini, C H; van Driel-Gesztelyi, L

    2014-01-01

    We describe the long-term evolution of a bipolar non-Hale active region which was observed from October, 1995, to January, 1996. Along these four solar rotations the sunspots and subsequent flux concentrations, during the decay phase of the region, were observed to move in such a way that by December their orientation conformed to the Hale-Nicholson polarity law. The sigmoidal shape of the observed soft X-ray coronal loops allows us to determine the sense of the twist in the magnetic configuration. This sense is confirmed by extrapolating the observed photospheric magnetic field, using a linear force-free approach, and comparing the shape of computed field lines to the observed coronal loops. This sense of twist agrees with that of the dominant helicity in the solar hemisphere where the region lies, as well as with the evolution observed in the longitudinal magnetogram during the first rotation. At first sight the relative motions of the spots may be miss-interpreted as the rising of an $\\Omega$-loop deformed...

  5. Si and Fe depletion in Galactic star-forming regions observed by the Spitzer Space Telescope

    Okada, Yoko; Miyata, Takashi; Okamoto, Yoshiko K; Sakon, Itsuki; Shibai, Hiroshi; Takahashi, Hidenori

    2008-01-01

    We report the results of the mid-infrared spectroscopy of 14 Galactic star-forming regions with the high-resolution modules of the Infrared Spectrograph (IRS) on board the Spitzer Space Telescope. We detected [SiII] 35um, [FeII] 26um, and [FeIII] 23um as well as [SIII] 33um and H2 S(0) 28um emission lines. Using the intensity of [NII] 122um or 205um and [OI] 146um or 63um reported by previous observations in four regions, we derived the ionic abundance Si+/N+ and Fe+/N+ in the ionized gas and Si+/O0 and Fe+/O0 in the photodissociation gas. For all the targets, we derived the ionic abundance of Si+/S2+ and Fe2+/S2+ for the ionized gas. Based on photodissociation and HII region models the gas-phase Si and Fe abundance are suggested to be 3-100% and <8% of the solar abundance, respectively, for the ionized gas and 16-100% and 2-22% of the solar abundance, respectively, for the photodissociation region gas. Since the [FeII] 26um and [FeIII] 23um emissions are weak, the high sensitivity of the IRS enables to de...

  6. Observation of the prominence cavity region using slitless eclipse flash spectra and space borne EUV filtergrams

    Bazin, Cyrille; Koutchmy, Serge; Lamy, Philippe; Tavabi, Ehsan

    2014-01-01

    We used total solar eclipse free of parasitic light for studying the prominence to corona interface, and the corresponding cavity in the context of the coronal physics. We analysed the visible continuum between the prominences to directly look at the electron density. We demonstrate some enhanced heating in the cavity region. Some similarities with the interface regions are shown: the photosphere to the chromosphere and the prominence to the corona interface. The optically thin neutral Helium at 4713 Å and the singly ionized Helium 4686 Å Paschen α lines are considered. We summed 80 slitless visible eclipse flash spectra that we compare with simultaneously obtained EUV SWAP/Proba2 174 Å images of ESA and AIA/SDO 171Å 193 Å 304 Å and 131 Å filtergrams. Intensity profiles in a radial direction are studied. We deduce the variation of the intensity ratio I(He I 4713) / I(He II 4686). Discussion: the temperature rises at the edge of the prominences. We evaluate for the first time with spectrophotometric accuracy the continuum modulations in prominence spectra. W-L intensity deficits are observed near the prominence boundaries in both eclipse spectra and in EUV images, confirming that the prominence -cavity regions correspond to a relative depression of plasma density of the surrounding corona. Conclusion: we demonstrate some enhanced heating occurring in these regions assuming hydrostatic equilibrium.

  7. On the area expansion of magnetic flux tubes in solar active regions

    Dudík, Jaroslav [DAMTP, CMS, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA (United Kingdom); Dzifčáková, Elena [Astronomical Institute of the Academy of Sciences of the Czech Republic, Fričova 298, 251 65 Ondřejov (Czech Republic); Cirtain, Jonathan W., E-mail: J.Dudik@damtp.cam.ac.uk, E-mail: elena@asu.cas.cz [NASA Marshall Space Flight Center, VP 62, Huntsville, AL 35812 (United States)

    2014-11-20

    We calculated the three-dimensional (3D) distribution of the area expansion factors in a potential magnetic field, extrapolated from the high-resolution Hinode/SOT magnetogram of the quiescent active region NOAA 11482. Retaining only closed loops within the computational box, we show that the distribution of area expansion factors show significant structure. Loop-like structures characterized by locally lower values of the expansion factor are embedded in a smooth background. These loop-like flux tubes have squashed cross-sections and expand with height. The distribution of the expansion factors show an overall increase with height, allowing an active region core characterized by low values of the expansion factor to be distinguished. The area expansion factors obtained from extrapolation of the Solar Optical Telescope magnetogram are compared to those obtained from an approximation of the observed magnetogram by a series of 134 submerged charges. This approximation retains the general flux distribution in the observed magnetogram, but removes the small-scale structure in both the approximated magnetogram and the 3D distribution of the area expansion factors. We argue that the structuring of the expansion factor can be a significant ingredient in producing the observed structuring of the solar corona. However, due to the potential approximation used, these results may not be applicable to loops exhibiting twist or to active regions producing significant flares.

  8. Radar observations of artificial E-region field-aligned irregularities

    E. Nossa

    2009-07-01

    Full Text Available Artificial E region field aligned plasma density irregularities (FAIs were generated using HAARP in four different experimental modes and observed with a coherent scatter radar imager located 450 km to the southwest where it could detect field-aligned backscatter. The experiments were conducted in July of 2008, during the Polar Aeronomy and Radio Science Summer School (PARS, during quiet conditions in the daytime when the E layer was dense and absorption was modest. The echoes observed during zenith and magnetic zenith heating experiments were deflected from their nominally anticipated horizontal positions toward the midpoint position. The occurrence of hysteresis when heating with amplitude modulated pulses implied the development of the resonance instability, although the threshold for the onset of instability appeared to be higher than what has been predicted theoretically. Heating experiments involving pump frequencies slightly above and below the second electron gyroharmonic frequency produced no significant differences in the observed echoes. Finally, heating with a pump frequency slightly above the E region critical frequency appears to have produced FAIs at two distinct altitudes where the upper-hybrid resonance condition could be satisfied.

  9. GRB follow-up observations in the East-Asian region

    Urata, Y; Ip, W H; Qiu, Y; Hu, J Y; Zhou, X; Tamagawa, T; Onda, K; Makishima, K; Zhou, Xn.

    2005-01-01

    In 2004, we established a Japan-Taiwan-China collaboration for GRB study in the East-Asian region. This serves as a valuable addition to the world-wide optical and infrared follow-up network, because the East-Asia region would otherwise be blank. We have been carrying out imaging and spectroscopic follow-up observations at Lulin (Taiwan), Kiso (Japan), WIDGET (Japan) and Xinglong (China). From Xinglong and Kiso, we can locate candidates and obtain early time spectra for afterglows. While WIDGET provides early time observations before the burst, the high-time resolution for multi-band light curves can be obtained at Lulin. With the data from these sites, we can obtain detailed information about the light curve and redshift of GRBs, which are important to understand the mechanism of the afterglows. Up to March 2005, ten follow-up observations have been provided by this East-Asia cooperation. Two optical afterglows were detected, GRB 040924 and GRB 041006. The results of the two detected afterglows are reported ...

  10. Spitzer Observations of M33 and the Hot Star, H II Region Connection

    Rubin, Robert H; Colgan, Sean W J; Dufour, Reginald J; Brunner, Gregory; McNabb, Ian A; Pauldrach, Adalbert W A; Erickson, Edwin F; Haas, Michael R; Citron, Robert I

    2008-01-01

    We have observed emission lines of [S IV] 10.51, H(7-6) 12.37, [Ne II] 12.81, [Ne III] 15.56, and [S III] 18.71 um in a number of extragalactic H II regions with the Spitzer Space Telescope. A previous paper presented our data and analysis for the substantially face-on spiral galaxy M83. Here we report our results for the local group spiral galaxy M33. The nebulae selected cover a wide range of galactocentric radii (R_G). The observations were made with the Infrared Spectrograph with the short wavelength, high resolution module. The above set of five lines is observed cospatially, thus permitting a reliable comparison of the fluxes. From the measured fluxes, we determine the ionic abundance ratios including Ne++/Ne+, S3+/S++, and S++/Ne+ and find that there is a correlation of increasingly higher ionization with larger R_G. By sampling the dominant ionization states of Ne (Ne+, Ne++) and S (S++, S3+) for H II regions, we can estimate the Ne/H, S/H, and Ne/S ratios. We find from linear least-squares fits that ...

  11. Spitzer Observations of M83 and the Hot Star, H II Region Connection

    Rubin, R H; Colgan, S W J; Dufour, R J; Ray, K L; Erickson, E F; Haas, M R; Pauldrach, A W A; Citron, R I; Rubin, Robert H.; Simpson, Janet P.; Colgan, Sean W.J.; Dufour, Reginald J.; Ray, Katherine L.; Erickson, Edwin F.; Haas, Michael R.; Pauldrach, Adalbert W.A.; Citron, Robert I.

    2007-01-01

    We have undertaken a program to observe emission lines of SIV 10.5, NeII 12.8, NeIII 15.6, & SIII 18.7 um in a number of extragalactic HII regions with the Spitzer Space Telescope. We report our results for the nearly face-on spiral galaxy M83. The nebulae selected cover a wide range of galactocentric radii (R_G). The observations were made with the Infrared Spectrograph in the short wavelength, high dispersion configuration. The above set of 4 lines is observed cospatially, thus permitting a reliable comparison of the fluxes. From the measured fluxes, we determine the ionic abundance ratios including Ne++/Ne+, S3+/S++, and S++/Ne+ and find that there is a correlation of increasingly higher ionization with larger R_G. By sampling the dominant ionization states of Ne and S for HII regions, Ne/S ~ (Ne+ + Ne++)/(S++ + S3+). Our findings of ratios that exceed the benchmark Orion value are more likely due to other effects than a true gradient in Ne/S. Both Ne and S are primary elements produced in alpha- chain...

  12. Transition Region and Chromospheric Signatures of Impulsive Heating Events. I. Observations

    Warren, Harry P; Crump, Nicholas A; Simoes, Paulo J A

    2016-01-01

    We exploit the high spatial resolution and high cadence of the Interface Region Imaging Spectrograph (IRIS) to investigate the response of the transition region and chromosphere to energy deposition during a small flare. Simultaneous observations from RHESSI provide constraints on the energetic electrons precipitating into the flare footpoints while observations of XRT, AIA, and EIS allow us to measure the temperatures and emission measures from the resulting flare loops. We find clear evidence for heating over an extended period on the spatial scale of a single IRIS pixel. During the impulsive phase of this event the intensities in each pixel for the Si IV 1402.770, C II 1334.535, Mg II 2796.354 and O I 1355.598 emission lines are characterized by numerous, small-scale bursts typically lasting 60s or less. Red shifts are observed in Si IV, C II, and Mg II during the impulsive phase. Mg II shows red-shifts during the bursts and stationary emission at other times. The Si IV and C II profiles, in contrast, are ...

  13. Deep XMM-Newton Observations of the NW Radio Relic Region of Abell 3667

    Sarazin, Craig L; Wik, Daniel R; Clarke, Tracy E

    2016-01-01

    The results of long XMM-Newton X-ray observations of the NW radio relic of Abell 3667 are presented. A shock is detected at the sharp outer edge of the radio relic, both in the X-ray surface brightness and the temperature profiles. The Mach number is M = 2.54^+0.80_-0.43. The temperature jump at the shock is larger than expected from the density jump, which may indicate that a dynamically important magnetic field aligned primarily parallel to the shock front is present. The gas temperature rises gradually over several arc minutes within the shock region. This could indicate that the shock energy is initially dissipated into some mix of thermal and nonthermal (e.g., turbulence) components, and that the nonthermal energy decays into heat in the post-shock region. The observed radio relic can be powered if ~0.2% of the energy dissipated in the shock goes into the (re)acceleration of relativistic electrons. We show that the observed steepening of the radio spectrum with distance behind the shock is consistent wit...

  14. Gamma-ray observations of the Crab Region using a coded-aperture telescope

    The region of the Galactic anticenter, including the Crab Nebula, was observed during a balloon flight of the University of New Hampshire Directional Gamma-Ray Telescope employing the coded-aperture imaging technique to image celestial gamma-radiation between 160 keV and 9.3 MeV. The background systematics are treated with a simple and relatively straightforward correction procedure. The results demonstrate that the coded-aperture procedure is a viable approach for imaging not only point sources of radiation, but also extended sources of emission. The results for the Crab's photon spectrum are consistent with a power-law spectrum. Upper limits on the flux levels of line emission at 405 keV and 1050 keV and on the flux from the X-ray binary source A0535 + 26 and diffuse Galactic emission from the anticenter region are derived. 35 references

  15. Greenland uplift and regional sea level changes from ICESat observations and GIA modelling

    Spada, G.; Ruggieri, G.; Sørensen, Louise Sandberg;

    2012-01-01

    response to current ice mass loss, which is not resolved by satellite gravity observations, we have specifically developed a high‐resolution regional elastic rebound (ER) model. The elastic component of vertical uplift is combined with estimates of the viscoelastic displacement fields associated with the......‐resolution GrIS mass balance, we study the time‐variations of various geophysical quantities in response to the current mass loss. They include vertical uplift and subsidence, geoid height variations, global patterns of sea level change (or fingerprints), and regional sea level variations along the coasts of...... Greenland. Long‐wavelength uplifts and gravity variations in response to current or past ice thickness variations are obtained solving the sea level equation, which accounts for both the elastic and the viscoelastic components of deformation. To capture the short‐wavelength components of vertical uplift in...

  16. Prominence Cavity Regions Observed Using SWAP 174 Å Filtergrams and Simultaneous Eclipse Flash Spectra

    Bazin, C.; Koutchmy, S.; Tavabi, E.

    2013-08-01

    SWAP images from PROBA2 taken at 174 Å in the Fe ix/ x lines are compared with simultaneous slitless flash spectra obtained during the solar total eclipse of 11 July 2010. Myriad faint low-excitation emission lines together with the He i and He ii Paschen α chromospheric lines are recorded on eclipse spectra where regions of limb prominences are obtained with space-borne imagers. We analyzed a deep flash spectrum obtained by summing 80 individual spectra to evaluate the intensity modulations of the continuum. Intensity deficits are observed and measured at the prominences boundaries in both eclipse and SWAP images. The prominence cavities interpreted as a relative depression of plasma density, produced inside the corona surrounding the prominences, and some intense heating occurring in these regions, are discussed. Photometric measurements are shown at different scales and different, spectrally narrow, intervals for both the prominences and the coronal background.

  17. Observation of rotation in star forming regions: clouds, cores, disks, and jets

    Belloche, Arnaud

    2013-01-01

    Angular momentum plays a crucial role in the formation of stars and planets. It has long been noticed that parcels of gas in molecular clouds need to reduce their specific angular momentum by 6 to 7 orders of magnitude to participate in the building of a typical star like the Sun. Several physical processes on different scales and at different stages of evolution can contribute to this loss of angular momentum. In order to set constraints on these processes and better understand this transfer of angular momentum, a detailed observational census and characterization of rotation at all stages of evolution and over all scales of star forming regions is necessary. This review presents the main results obtained in low-mass star forming regions over the past four decades in this field of research. It addresses the search and characterization of rotation in molecular clouds, prestellar and protostellar cores, circumstellar disks, and jets. Perspectives offered by ALMA are briefly discussed.

  18. Geodetic observation of sea-level change and crustal deformation in the Baltic Sea region

    Richter, A.; Groh, A.; Dietrich, R.

    Based on tide gauge observations spanning almost 200 years, homogeneous time series of the mean relative sea level were derived for nine sites at the southern coast of the Baltic Sea. Our regionally concentrated data were complemented by long-term relative sea-level records retrieved from the data base of the Permanent Service for Mean Sea Level (PSMSL). From these records relative sea-level change rates were derived at 51 tide gauge stations for the period between 1908 and 2007. A minimum observation time of 60 years is required for the determination of reliable sea-level rates. At present, no anthropogenic acceleration in sea-level rise is detected in the tide gauge observations in the southern Baltic. The spatial variation of the relative sea-level rates reflects the fingerprint of GIA-induced crustal uplift. Time series of extreme sea levels were also inferred from the tide gauge records. They were complemented by water level information from historic storm surge marks preserved along the German Baltic coast. Based on this combined dataset the incidence and spatial variation of extreme sea levels induced by storm surges were analysed yielding important information for hazard assessments. Permanent GPS observations were used to determine recent crustal deformation rates for 44 stations in the Baltic Sea region. The GPS derived height change rates were applied to reduce the relative sea-level changes observed by tide gauges yielding an estimate for the eustatic sea-level change. For 13 tide gauge-GPS colocation sites a mean eustatic sea-level trend of 1.3 mm/a was derived for the last 100 years.

  19. Low-frequency magnetic field fluctuations in Venus' solar wind interaction region: Venus Express observations

    L. Guicking

    2010-04-01

    Full Text Available We investigate wave properties of low-frequency magnetic field fluctuations in Venus' solar wind interaction region based on the measurements made on board the Venus Express spacecraft. The orbit geometry is very suitable to investigate the fluctuations in Venus' low-altitude magnetosheath and mid-magnetotail and provides an opportunity for a comparative study of low-frequency waves at Venus and Mars. The spatial distributions of the wave properties, in particular in the dayside and nightside magnetosheath as well as in the tail and mantle region, are similar to observations at Mars. As both planets do not have a global magnetic field, the interaction process of the solar wind with both planets is similar and leads to similar instabilities and wave structures. We focus on the spatial distribution of the wave intensity of the fluctuating magnetic field and detect an enhancement of the intensity in the dayside magnetosheath and a strong decrease towards the terminator. For a detailed investigation of the intensity distribution we adopt an analytical streamline model to describe the plasma flow around Venus. This allows displaying the evolution of the intensity along different streamlines. It is assumed that the waves are generated in the vicinity of the bow shock and are convected downstream with the turbulent magnetosheath flow. However, neither the different Mach numbers upstream and downstream of the bow shock, nor the variation of the cross sectional area and the flow velocity along the streamlines play probably an important role in order to explain the observed concentration of wave intensity in the dayside magnetosheath and the decay towards the nightside magnetosheath. But, the concept of freely evolving or decaying turbulence is in good qualitative agreement with the observations, as we observe a power law decay of the intensity along the streamlines. The observations support the assumption of wave convection through the magnetosheath, but

  20. ANTIFUNGAL ACTIVITY OF GEOTHERMAL FLUIDS FROM DIFFERENT REGIONS OF TURKEY

    Ahmet Ali Var,

    2012-07-01

    Full Text Available Antifungal effects of geothermal fluids obtained from the Ankara, Afyon, Denizli, and Eskişehir regions of Turkey on white-rot (Trametes versicolor, MAD-697 and brown-rot (Coniophora puteana, FPRL 11E fungus (Basidiomycetes were studied. Fungal experiments were performed on kraft paper and Scots pine wood (Pinus sylvestris L.. We used non-concentrated geothermal water and concentrated geothermal water (via evaporation in ratios of 25%, 50%, and 75%. To evaluate the results, we measured the concentration of specific minerals in the geothermal fluids such as boron (B, arsenic (As, copper (Cu, sulfate (SO4, sodium (Na, chloride (Cl, fluoride (F, potassium (K, and ammonia (NH3. The highest antifungal effect was observed for a geothermal fluid from the Denizli region, followed by Ankara, Afyon, and Eskişehir, in decreasing order. Antifungal properties of GFs are thought to be associated with the type and amount of mineral substances. In addition, the antifungal effects increased with increasing concentrations of geothermal water.

  1. Occurrence and location of concentrated load and generator regions observed by Cluster in the plasma sheet

    M. Hamrin

    2009-11-01

    Full Text Available Here, and in a companion paper by Hamrin et al. (2009 [Scale size and life time of energy conversion regions observed by Cluster in the plasma sheet], we investigate localized energy conversion regions (ECRs in the Earth's plasma sheet. In total we have studied 151 ECRs within 660 h of plasma sheet data from the summer and fall of 2001 when Cluster was close to apogee at an altitude of about 15–20 RE. Cluster offers appropriate conditions for the investigation of energy conversion by the evaluation of the power density, E·J, where E is the electric field and J the current density. From the sign of the power density, we have identified more than three times as many Concentrated Load Regions (CLRs as Concentrated Generator Regions (CGRs. We also note that the CLRs appear to be stronger. To our knowledge, these are the first in situ observations confirming the general notion of the plasma sheet, on the average, behaving as a load. At the same time the plasma sheet appears to be highly structured, with energy conversion occurring in both directions between the fields and the particles. From our data we also find that the CLRs appear to be located closer to the neutral sheet, while CGRs prefer locations towards the plasma sheet boundary layer (PSBL. For both CLRs and CGRs, E and J in the GSM y (cross-tail direction dominate the total power density, even though the z contribution occasionally can be significant. The prevalence of the y-direction seems to be weaker for the CGRs, possibly related to a higher fluctuation level near the PSBL.

  2. Seismic Halos Around Active Regions: An MHD Theory

    Hanasoge, Shravan M

    2007-01-01

    Comprehending the manner in which magnetic fields affect propagating waves is a first step toward the helioseismic construction of accurate models of active region sub-surface structure and dynamics. Here, we present a numerical method to compute the linear interaction of waves with magnetic fields embedded in a solar-like stratified background. The ideal Magneto-Hydrodynamic (MHD) equations are solved in a 3-dimensional box that straddles the solar photosphere, extending from 35 Mm within to 1.2 Mm into the atmosphere. One of the challenges in performing these simulations involves generating a Magneto-Hydro-Static (MHS) state wherein the stratification assumes horizontal inhomogeneity in addition to the strong vertical stratification associated with the near-surface layers. Keeping in mind that the aim of this effort is to understand and characterize linear MHD interactions, we discuss a means of computing statically consistent background states. Results from a simulation of waves interacting with a flux tub...

  3. Witnessing hateful people in pain modulates brain activity in regions associated with physical pain and reward.

    GlennRyanFox

    2013-10-01

    Full Text Available How does witnessing a hateful person in pain compare to witnessing a likable person in pain? The current study compared the brain bases for how we perceive likable people in pain with those of viewing hateful people in pain. While social bonds are built through sharing the plight and pain of others in the name of empathy, viewing a hateful person in pain also has many potential ramifications. In this functional Magnetic Resonance Imaging (fMRI study, Caucasian Jewish male participants viewed videos of (1 disliked, hateful, anti-Semitic individuals, and (2 liked, non-hateful, tolerant individuals in pain. The results showed that, compared with viewing liked people, viewing hateful people in pain elicited increased responses in regions associated with observation of physical pain (the insular cortex, the anterior cingulate cortex, and the somatosensory cortex, reward processing (the striatum, and frontal regions associated with emotion regulation. Functional connectivity analyses revealed connections between seed regions in the left anterior cingulate cortex and right insular cortex with reward regions, the amygdala, and frontal regions associated with emotion regulation. These data indicate that regions of the brain active while viewing someone in pain may be more active in response to the danger or threat posed by witnessing the pain of a hateful individual more so than the desire to empathize with a likable person’s pain.

  4. Slow Magneto-acoustic Waves Observed above Quiet-Sun Region in a Dark Cavity

    Liu, Jiajia; Wang, Yuming; Liu, Rui; Wang, Bin; Liao, Chijian; Shen, Chenglong; Zheng, Huinan; Miao, Bin; Su, Zhenpeng; Wang, S

    2012-01-01

    Waves play a crucial role in diagnosing the plasma properties of various structures in the solar corona and coronal heating. Slow magneto-acoustic (MA) waves are one of the important magnetohydrodynamic waves. In past decades, numerous slow MA waves were detected above the active regions and coronal holes, but rarely found elsewhere. Here, we investigate a `tornado'-like structure consisting of quasi-periodic streaks within a dark cavity at about 40--110 Mm above the quiet-Sun region on 2011 September 25. Our analysis reveals that these streaks are actually slow MA wave trains. The properties of these wave trains, including the phase speed, compression ratio, kinetic energy density, etc., are similar to those of the reported slow MA waves, except that the period of these waves is about 50 s, much shorter than the typical reported values (3--5 minutes).

  5. Radar observations of F region field-aligned irregularities over Hainan island, China in 2014-2015

    Shang, She-Ping; Wu, Qiongzhi; Chunxiao, Yan; Yan, Jingye; Shi, Jiankui; Yang, Guotao

    2016-07-01

    The morphology characteristics of low latitude F region 3-m scale field-aligned irregularities (FAIs) have been investigated by using the continuous observation of Hainan VHF radar (19.5ºN,109.1ºE,dip latitude:14.0ºN) in 2014-2015. The monthly mean F10.7 solar flux show the clear decrease from the peak in the start of 2014 to the foot in the end of 2015. F region FAIs can be further classified into the three cases: radar plumes (RP), broad spread F (BSF) and weak spread F (WSF), in which the first are mainly generated and developed within the field of view (FoV) of radar and the latter two generally originate outside of the FoV of radar and drift into the FoV of radar. They indicate the different phases of generation, evolution and decay of low latitude F region irregularities. The main results exhibit the F region FAIs mainly present in Feb.-Apr. and in Sep.-Nov. near the two equinoxes and are greatly reduced in May-Aug. near summer solstice, and almost completely disappeared in Dec.-Jan. near winter solstice, which are greatly affected by the solar activity. F region FAIs are more robust in spring equinox than in fall equinox, which can be shown as the occurrence rate, the structure and evolution, the duration time and so on. In spring equinox, the occurrence rate is far higher, and F region FAIs show the more structures and the longer duration time. RP near sunset are greatly enhanced. The following BSF and WSF can present intermittently and may persist into the post-midnight. F region FAIs in summer solstice mainly show BSF and WSF with the clear time delay. BSF mainly present in the pre-midnight, and there are mostly WSF in the post-midnight. The clear decrease of sola flux cause different effects to the occurrence of F region FAIs in the equinoxes and summer solstice. F region FAIs are greatly reduced in the equinoxes, in which RP are greatly reduced compared with BSF and WSF. F region FAIs seem not to be evidently affected in the summer solstice, in which

  6. VERY LARGE ARRAY OH ZEEMAN OBSERVATIONS OF THE STAR-FORMING REGION S88B

    Sarma, A. P.; Eftimova, M. [Physics Department, DePaul University, 2219 N. Kenmore Ave., Byrne Hall 211, Chicago, IL 60614 (United States); Brogan, C. L. [National Radio Astronomy Observatory, Charlottesville, VA 22903 (United States); Bourke, T. L. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Troland, T. H., E-mail: asarma@depaul.edu [Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506 (United States)

    2013-04-10

    We present observations of the Zeeman effect in OH thermal absorption main lines at 1665 and 1667 MHz taken with the Very Large Array toward the star-forming region S88B. The OH absorption profiles toward this source are complicated, and contain several blended components toward a number of positions. Almost all of the OH absorbing gas is located in the eastern parts of S88B, toward the compact continuum source S88B-2 and the eastern parts of the extended continuum source S88B-1. The ratio of 1665/1667 MHz OH line intensities indicates the gas is likely highly clumped, in agreement with other molecular emission line observations in the literature. S88-B appears to present a similar geometry to the well-known star-forming region M17, in that there is an edge-on eastward progression from ionized to molecular gas. The detected magnetic fields appear to mirror this eastward transition; we detected line-of-sight magnetic fields ranging from 90 to 400 {mu}G, with the lowest values of the field to the southwest of the S88B-1 continuum peak, and the highest values to its northeast. We used the detected fields to assess the importance of the magnetic field in S88B by a number of methods; we calculated the ratio of thermal to magnetic pressures, we calculated the critical field necessary to completely support the cloud against self-gravity and compared it to the observed field, and we calculated the ratio of mass to magnetic flux in terms of the critical value of this parameter. All these methods indicated that the magnetic field in S88B is dynamically significant, and should provide an important source of support against gravity. Moreover, the magnetic energy density is in approximate equipartition with the turbulent energy density, again pointing to the importance of the magnetic field in this region.

  7. First observation of low-energy {\\gamma}-ray enhancement in the rare-earth region

    Simon, A.; Guttormsen, M.; Larsen, A.C.; Beausang, C. W.; Humby, P.; Burke, J.T.; Casperson, R. J.; Hughes, R. O.; Ross, T. J.; Allmond, J.M.; Chyzh, R.; Dag, M.; Koglin, J.; McCleskey, E.; McCleskey, M.

    2016-01-01

    The {\\gamma}-ray strength function and level density in the quasi-continuum of 151,153Sm have been measured using BGO shielded Ge clover detectors of the STARLiTeR system. The Compton shields allow for an extraction of the {\\gamma} strength down to unprecedentedly low {\\gamma} energies of about 500 keV. For the first time an enhanced low- energy {\\gamma}-ray strength has been observed in the rare-earth region. In addition, for the first time both the upbend and the well known scissors resonan...

  8. Observations of E region irregularities generated at auroral latitudes by a high-power radio wave

    Djuth, F. T.; Jost, R. J.; Noble, S. T.; Gordon, W. E.; Stubbe, P.

    1985-01-01

    The initial results of a series of observations made with the high-power HF heating facility near Tromso, Norway are reported. During these experiments, attention was focused on the production of artificial geomagnetic field-aligned irregularities (AFAIs) in the auroral E region by HF waves. A mobile 46.9-MHz radar was used to diagnose the formation of AFAIs having spatial scales of 3.2 across geomagnetic field lines. The dynamic characteristics of the AFAIs are discussed within the context of current theoretical work dealing with the natural production of AFAIs in the ionosphere.

  9. Titan's atmosphere from Voyager infrared observations. I. The gas composition of Titan's equatorial region

    After inferring minor atmospheric-constituent abundances in Titan's equatorial region from Voyager 1 IR spectra, a stratospheric temperature profile is derived. An analysis of three different sections has yielded stratospheric mole fractions for C2H2, C2H4, C2H6, C3H4, C3H8, C4H2, HCN, and CO2; an altitude-dependent CO2 profile has been tested against observations, but no conclusive data on vertical distribution could be extracted. Emission-line formation for all minor components originates from the 1-20 mbar, or 75-200 km, pressure levels. 47 refs

  10. ANALYSIS ON CORRELATIONS BETWEEN SUBSURFACE KINETIC HELICITY AND PHOTOSPHERIC CURRENT HELICITY IN ACTIVE REGIONS

    An investigation on correlations between photospheric current helicity and subsurface kinetic helicity is carried out by analyzing vector magnetograms and subsurface velocities for two rapidly developing active regions. The vector magnetograms are from the Solar Dynamics Observatory/Helioseismic and Magnetic Imager (SDO/HMI) observed Stokes parameters, and the subsurface velocity is from time-distance data-analysis pipeline using HMI Dopplergrams. Over a span of several days, the evolution of the weighted current helicity shows a tendency similar to that of the weighted subsurface kinetic helicity, attaining a correlation coefficient above 0.60 for both active regions. Additionally, there seems to be a phase lag between the evolutions of the unweighted current and subsurface kinetic helicities for one of the active regions. The good correlation between these two helicities indicates that there is some intrinsic connection between the interior dynamics and photospheric magnetic twistedness inside active regions, which may help to interpret the well-known hemispheric preponderance of current-helicity distribution.

  11. Active region plasma outflows as sources of slow/intermediate solar wind

    van Driel-Gesztelyi, Lidia M.

    2015-08-01

    L. van Driel-Gesztelyi (1,2,3), D. Baker (1), P. Démoulin (2), Culhane, J.L. (1), M.L. DeRosa (4) C.H. Mandrini (5,6), D.H. Brooks (7), A.N. Fazakerley (1), L.K. Harra (1), L. Zhao (7), T.H. Zurbuchen (7), F.A. Nuevo (5,6), A.M. Vásquez (5,6), G.D. Cristiani (5,6) M. Pick (2)1) UCL/MSSL, UK, (2) Paris Observatory, LESIA, CNRS, France, (3) Konkoly Observatory, Hungary, (4) Lockheed Martin Solar and Astrophysics Laboratory, USA, (5) IAFE, CONICET-UBA, Argentina (6) FCEN, UBA, Argentina (7) Dept. of Atmospheric, Oceanic and Earth Sciences, Univ. of Michigan, USAWe analyse plasma upflows of tens of km/s from the edges of solar active regions discovered by Hinode/EIS and investigate whether or not they become outflows, i.e. find their way into the solar wind. We analyse two magnetic configurations: bipolar and quadrupolar and find that the active region plasma may be directly channeled into the solar wind via interchange reconnection at a high-altitude null point above the active region especially when active regions are located besides coronal holes or in a more complex way via multiple reconnections even from under a closed helmet streamer. We relate the solar observations to in-situ slow/intermediate solar wind streams.

  12. Methane depletion in both polar regions of Uranus inferred from HST/STIS and Keck/NIRC2 observations

    Sromovsky, Lawrence; Fry, Patrick; Hammel, Heidi; de Pater, Imke; Rages, Kathy

    2015-01-01

    From STIS observations of Uranus in 2012, we found that the methane volume mixing ratio declined from about 4% at low latitudes to about 2% at 60 deg N and beyond. This is similar to that found in the south polar regions in 2002, in spite of what appears to be strikingly different convective activity in the two regions. Keck and HST imaging observations close to equinox imply that the depletions were simultaneously present in 2007, suggesting they are persistent features. The depletions appear to be mainly restricted to the upper troposphere, with depth increasing poleward from about 30 deg N, reaching ~4 bars at 45 deg N and perhaps much deeper at 70 deg N. The latitudinal variations in degree and depth of the depletions are important constraints on models of meridional circulation. Our observations are qualitatively consistent with previously suggested circulation cells in which rising methane-rich gas at low latitudes is dried out by condensation and sedimentation of methane ice particles as the gas ascend...

  13. Critical analysis of the electrostatic turbulence enhancements observed by DEMETER over the Sichuan region during the earthquake preparation

    T. Onishi

    2011-02-01

    Full Text Available In this paper, we report initial results from a detailed statistical study of the plasma waves observed by the DEMETER satellite over the Sichuan region during a period of 20 days encompassing the large earthquake of magnitude M =7.9 that occurred on 12 May 2008. The main objective of this paper is to present a statistical method to process and analyze plasma wave data and assist in detecting possible earthquake precursors among larger irregular disturbances arising from the natural variability of the ionized environment of the Earth. This method, presently used for dayside observations, involves two stages. First, VLF wave spectra are processed to recognize the various types of plasma waves usually observed at mid and low latitudes and derive a reduced number of parameters that fully characterize these emissions and may be conveniently used for a detailed statistical study. In a second stage, we perform a statistical analysis of the results by taking into account two "reference zones" displaced respectively 30° eastward and westward from the "epicentre zone". Plasma and wave disturbances possibly induced by earthquakes in preparation are likely to maximize close to the "epicentre zone", while natural disturbances associated, in particular, with the varying magnetic activity are rather uniform over a wider longitude sector, thus enabling the use of observations over the reference zones as a base line. The initial results of this study show a deviation of the power spectrum of electrostatic turbulence in the epicentre zone about 6 days prior to the earthquake but no significant anomalous variations can be observed on other characteristics of plasma waves. From the analysis of the data over the two reference~zones and using recently produced sector magnetic activity indices, we conclude that the enhancement of electrostatic turbulence is associated with magnetospheric processes rather than with pre-seismic activity.

  14. Chromospheric activity above changign photospheric magnetic and velocity fields of developing active regions

    Bumba, Václav; Klvaňa, Miroslav; Kálmán, B.; Rompolt, B.; Rudawy, P.

    San Francisco: Astronomical Society of the Pacific, 1998, s. 224-228. (ASP Conference series.. 155). [Euroconference : Three-dimensional structure of solar active regions : Advaces in solar physics. Preveza (GR), 07.10.1997-12.10.1997] Institutional research plan: CEZ:AV0Z1003909 Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

  15. Rocket-borne particle, field, and plasma observations in the cleft region. [ionospheric sounding

    Ungstrup, E.; Bahnsen, A.; Olesen, J. K.; Primdahl, F.; Spangslev, F.; Heikkila, W. J.; Klumpar, D. M.; Winningham, J. D.; Fahleson, U.; Falthammar, C.-G.

    1975-01-01

    Results are reported for comprehensive observations of magnetic and electric fields together with ambient and suprathermal plasmas above the dayside auroral oval with rocket-borne instrumentation which penetrated the cleft region. Measurements were also obtained equatorward and poleward of the cleft. Convection velocities as inferred from electric-field measurements were generally toward noon equatorward of the cleft and were antisunward over the polar cap. Observations of electron temperatures, electric fields, and low-frequency electrostatic noise provide strong evidence of a plasma instability (Farley-Buneman) in the E-layer associated with the appearance of the 'slant E condition' identified in ground-acquired ionograms. The positions of these measurements relative to that of the cleft were firmly established via the determination of the plasma environment with an electrostatic analyzer.

  16. First observation of low-energy {\\gamma}-ray enhancement in the rare-earth region

    Simon, A; Larsen, A C; Beausang, C W; Humby, P; Burke, J T; Casperson, R J; Hughes, R O; Ross, T J; Allmond, J M; Chyzh, R; Dag, M; Koglin, J; McCleskey, E; McCleskey, M; Ota, S; Saastamoinen, A

    2016-01-01

    The {\\gamma}-ray strength function and level density in the quasi-continuum of 151,153Sm have been measured using BGO shielded Ge clover detectors of the STARLiTeR system. The Compton shields allow for an extraction of the {\\gamma} strength down to unprecedentedly low {\\gamma} energies of about 500 keV. For the first time an enhanced low- energy {\\gamma}-ray strength has been observed in the rare-earth region. In addition, for the first time both the upbend and the well known scissors resonance have been observed simultaneously for the same nucleus. Hauser-Feshbach calculations show that this strength enhancement at low {\\gamma} energies could have an impact of 2-3 orders of magnitude on the (n,{\\gamma}) reaction rates for the r-process nucleosynthesis.

  17. Physical characterisation of southern massive star-forming regions using Parkes NH$_3$ observations

    Hill, T; Pinte, C; Cunningham, M R; Burton, M G; Minier, V

    2009-01-01

    We have undertaken a Parkes ammonia spectral line study, in the lowest two inversion transitions, of southern massive star formation regions, including young massive candidate protostars, with the aim of characterising the earliest stages of massive star formation. 138 sources from the submillimetre continuum emission studies of Hill et al., were found to have robust (1,1) detections, including two sources with two velocity components, and 102 in the (2,2) transition. We determine the ammonia line properties of the sources: linewidth, flux density, kinetic temperature, NH$_3$ column density and opacity, and revisit our SED modelling procedure to derive the mass for 52 of the sources. By combining the continuum emission information with ammonia observations we substantially constrain the physical properties of the high-mass clumps. There is clear complementarity between ammonia and continuum observations for derivations of physical parameters. The MM-only class, identified in the continuum studies of Hill et a...

  18. 51.8 micron forbidden O III line emission observed in four galatic H II regions

    Melnick, G.; Gull, G. E.; Harwit, M.

    1979-01-01

    The 51.8-micron forbidden O III line has been detected in four H II regions: M42, M17, W51, and NGC 6357A. The respective line strengths are 7 x 10 to the -15th, 1.0 x 10 to the -14th, 2.1 x 10 to the -15th, and 2.6 x 10 to the -15th W/sq cm. The observations are consistent with a previously reported line position and place the line at 51.80 + or - 0.05-micron. When combined with the 88.35-micron forbidden O III observations reported earlier, clumpiness is found to be an important factor in NGC 6357A and M42 and nonnegligible in W51 and M17. The combined data also suggest an O III abundance of about 0.0003 times the electron density, which is a factor of 2 greater than a number of investigators have reported.

  19. EVIDENCE FOR DEPARTURE FROM A POWER-LAW FLARE SIZE DISTRIBUTION FOR A SMALL SOLAR ACTIVE REGION

    Active region 11029 was a small, highly flare-productive solar active region observed at a time of extremely low solar activity. The region produced only small flares: the largest of the >70 Geostationary Observational Environmental Satellite (GOES) events for the region has a peak 1-8 A flux of 2.2 x 10-6 W m-2 (GOES C2.2). The background-subtracted GOES peak-flux distribution suggests departure from power-law behavior above 10-6 W m-2, and a Bayesian model comparison strongly favors a power-law plus rollover model for the distribution over a simple power-law model. The departure from the power law is attributed to this small active region having a finite amount of energy. The rate of flaring in the region varies with time, becoming very high for 2 days coinciding with the onset of an increase in complexity of the photospheric magnetic field. The observed waiting-time distribution for events is consistent with a piecewise-constant Poisson model. These results present challenges for models of flare statistics and of energy balance in solar active regions.

  20. Antioxidant Activity of Some Selected Medicinal Plants in Southern Region of India.

    V Rathabai

    2013-12-01

    Full Text Available The present study was undertaken to find the antioxidant value of certain medicinal plants in Tamilnadu region. Antioxidants have been reported to prevent oxidative damage caused by free radical and can be usedin cardiovascular, anti-inflammatory, diabetes and cancer diseases. The amount of total phenols, flavonoids and radical scavenging activity has been studied. Major amount of phenols were determined in Corchorusaestuans followed byroot of Coleus Forskohlii. Moreover, maximum flavonoid content was found to be present in the Corchorusaestuans followed by Coleus Forskohlii. However, high radical scavenging activity was observed in Corchorusaestuans followed by leaf of Carica papaya and Coleus Forskohlii.

  1. Aura OMI Observations of Regional SO2 and NO2 Pollution Changes from 2005 to 2015

    Krotkov, Nickolay A.; McLinden, Chris A.; Li, Can; Lamsal, Lok N.; Celarier, Edward A.; Marchenko, Sergey V.; Swartz, William H.; Bucsela, Eric J.; Joiner, Joanna; Duncan, Bryan N.; Boersma, K. Folkert; Veefkind, J. Pepijn; Levelt, Pieternel F.; Fioletov, Vitali E.; Dickerson, Russell R.; He, Hao; Lu, Zifeng; Streets, David G.

    2016-01-01

    The Ozone Monitoring Instrument (OMI) onboard NASA's Aura satellite has been providing global observations of the ozone layer and key atmospheric pollutant gases, such as nitrogen dioxide (NO2) and sulfur dioxide (SO2), since October 2004. The data products from the same instrument provide consistent spatial and temporal coverage and permit the study of anthropogenic and natural emissions on local-to-global scales. In this paper, we examine changes in SO2 and NO2 over some of the world's most polluted industrialized regions during the first decade of OMI observations. In terms of regional pollution changes, we see both upward and downward trends, sometimes in opposite directions for NO2 and SO2, for different study areas. The trends are, for the most part, associated with economic and/or technological changes in energy use, as well as regional regulatory policies. Over the eastern US, both NO2 and SO2 levels decreased dramatically from 2005 to 2015, by more than 40 and 80 percent, respectively, as a result of both technological improvements and stricter regulations of emissions. OMI confirmed large reductions in SO2 over eastern Europe's largest coal-fired power plants after installation of flue gas desulfurization devices. The North China Plain has the world's most severe SO2 pollution, but a decreasing trend has been observed since 2011, with about a 50 percent reduction in 2012-2015, due to an economic slowdown and government efforts to restrain emissions from the power and industrial sectors. In contrast, India's SO2 and NO2 levels from coal power plants and smelters are growing at a fast pace, increasing by more than 100 and 50 percent, respectively, from 2005 to 2015. Several SO2 hot spots observed over the Persian Gulf are probably related to oil and gas operations and indicate a possible underestimation of emissions from these sources in bottom-up emission inventories. Overall, OMI observations have proved valuable in documenting rapid changes in air

  2. Aura OMI observations of regional SO2 and NO2 pollution changes from 2005 to 2014

    N. A. Krotkov

    2015-10-01

    Full Text Available The Ozone Monitoring Instrument (OMI onboard NASA's Aura satellite has been providing global observations of the ozone layer and key atmospheric pollutant gases, such as nitrogen dioxide (NO2 and sulfur dioxide (SO2, since October 2004. The data products from the same instrument provide consistent spatial and temporal coverage and permit the study of anthropogenic and natural emissions on local-to-global scales. In this paper we examine changes in SO2 and NO2 over some of the world's most polluted industrialized regions during the first decade of OMI observations. In terms of regional pollution changes, we see both upward and downward trends, sometimes in opposite directions for NO2 and SO2, for the different study areas. The trends are, for the most part, associated with economic and/or technological changes in energy use, as well as regional regulatory policies. Over the eastern US, both NO2 and SO2 levels decreased dramatically from 2005 to 2014, by more than 40 and 80 %, respectively, as a result of both technological improvements and stricter regulations of emissions. OMI confirmed large reductions in SO2 over eastern Europe's largest coal power plants after installation of flue gas desulfurization devices. The North China Plain has the world's most severe SO2 pollution, but a decreasing trend has been observed since 2011, with about a 50 % reduction in 2012–2014, due to an economic slowdown and government efforts to restrain emissions from the power and industrial sectors. In contrast, India's SO2 and NO2 levels from coal power plants and smelters are growing at a fast pace, increasing by more than 100 and 50 %, respectively, from 2005 to 2014. Several SO2 hot spots observed over the Persian Gulf are probably related to oil and gas operations and indicate a possible underestimation of emissions from these sources in bottom-up emission inventories. Overall, OMI observations have proved to be very valuable in documenting rapid changes in

  3. Aura OMI observations of regional SO2 and NO2 pollution changes from 2005 to 2014

    Krotkov, N. A.; McLinden, C. A.; Li, C.; Lamsal, L. N.; Celarier, E. A.; Marchenko, S. V.; Swartz, W. H.; Bucsela, E. J.; Joiner, J.; Duncan, B. N.; Boersma, K. F.; Veefkind, J. P.; Levelt, P. F.; Fioletov, V. E.; Dickerson, R. R.; He, H.; Lu, Z.; Streets, D. G.

    2015-10-01

    The Ozone Monitoring Instrument (OMI) onboard NASA's Aura satellite has been providing global observations of the ozone layer and key atmospheric pollutant gases, such as nitrogen dioxide (NO2) and sulfur dioxide (SO2), since October 2004. The data products from the same instrument provide consistent spatial and temporal coverage and permit the study of anthropogenic and natural emissions on local-to-global scales. In this paper we examine changes in SO2 and NO2 over some of the world's most polluted industrialized regions during the first decade of OMI observations. In terms of regional pollution changes, we see both upward and downward trends, sometimes in opposite directions for NO2 and SO2, for the different study areas. The trends are, for the most part, associated with economic and/or technological changes in energy use, as well as regional regulatory policies. Over the eastern US, both NO2 and SO2 levels decreased dramatically from 2005 to 2014, by more than 40 and 80 %, respectively, as a result of both technological improvements and stricter regulations of emissions. OMI confirmed large reductions in SO2 over eastern Europe's largest coal power plants after installation of flue gas desulfurization devices. The North China Plain has the world's most severe SO2 pollution, but a decreasing trend has been observed since 2011, with about a 50 % reduction in 2012-2014, due to an economic slowdown and government efforts to restrain emissions from the power and industrial sectors. In contrast, India's SO2 and NO2 levels from coal power plants and smelters are growing at a fast pace, increasing by more than 100 and 50 %, respectively, from 2005 to 2014. Several SO2 hot spots observed over the Persian Gulf are probably related to oil and gas operations and indicate a possible underestimation of emissions from these sources in bottom-up emission inventories. Overall, OMI observations have proved to be very valuable in documenting rapid changes in air quality over

  4. Aura OMI observations of regional SO2 and NO2 pollution changes from 2005 to 2015

    Krotkov, Nickolay A.; McLinden, Chris A.; Li, Can; Lamsal, Lok N.; Celarier, Edward A.; Marchenko, Sergey V.; Swartz, William H.; Bucsela, Eric J.; Joiner, Joanna; Duncan, Bryan N.; Folkert Boersma, K.; Pepijn Veefkind, J.; Levelt, Pieternel F.; Fioletov, Vitali E.; Dickerson, Russell R.; He, Hao; Lu, Zifeng; Streets, David G.

    2016-04-01

    The Ozone Monitoring Instrument (OMI) onboard NASA's Aura satellite has been providing global observations of the ozone layer and key atmospheric pollutant gases, such as nitrogen dioxide (NO2) and sulfur dioxide (SO2), since October 2004. The data products from the same instrument provide consistent spatial and temporal coverage and permit the study of anthropogenic and natural emissions on local-to-global scales. In this paper, we examine changes in SO2 and NO2 over some of the world's most polluted industrialized regions during the first decade of OMI observations. In terms of regional pollution changes, we see both upward and downward trends, sometimes in opposite directions for NO2 and SO2, for different study areas. The trends are, for the most part, associated with economic and/or technological changes in energy use, as well as regional regulatory policies. Over the eastern US, both NO2 and SO2 levels decreased dramatically from 2005 to 2015, by more than 40 and 80 %, respectively, as a result of both technological improvements and stricter regulations of emissions. OMI confirmed large reductions in SO2 over eastern Europe's largest coal-fired power plants after installation of flue gas desulfurization devices. The North China Plain has the world's most severe SO2 pollution, but a decreasing trend has been observed since 2011, with about a 50 % reduction in 2012-2015, due to an economic slowdown and government efforts to restrain emissions from the power and industrial sectors. In contrast, India's SO2 and NO2 levels from coal power plants and smelters are growing at a fast pace, increasing by more than 100 and 50 %, respectively, from 2005 to 2015. Several SO2 hot spots observed over the Persian Gulf are probably related to oil and gas operations and indicate a possible underestimation of emissions from these sources in bottom-up emission inventories. Overall, OMI observations have proved valuable in documenting rapid changes in air quality over different

  5. Observations of gravity wave forcing of themesopause region during the January 2013 major Sudden Stratospheric Warming

    deWit, R J; Espy, P J; Orsolini, Y J; Limpasuvan, V; Kinnison, D E

    2016-01-01

    Studies of vertical and interhemispheric coupling during Sudden Stratospheric Warmings (SSWs) suggest that gravity wave (GW) momentum flux divergence plays a key role in forcing the middle atmosphere, although observational validation of GW forcing is limited. We present a whole atmosphere view of zonal winds from the surface to 100 km during the January 2013 major SSW, together with observed GW momentum fluxes in the mesopause region derived from uninterrupted high-resolution meteor radar observations from an All-Sky Interferometric Meteor Radar system located at Trondheim, Norway (63.4 $^{\\circ}$N, 10.5 $^{\\circ}$E). Observations show GW momentum flux divergence 6 days prior to the SSW onset, producing an eastward forcing with peak values of $\\sim$+145 $\\pm$ 60m $s^{-1}$ $d^{-1}$. As the SSW evolves, GW forcing turns westward, reaching a minimum of $\\sim$-240 $\\pm$ 70 m $s^{-1}$ $d^{-1}$ $\\sim$+18 days after the SSW onset. These results are discussed in light of previous studies and simulations using the Wh...

  6. Direct Observations of Plasma Upflows and Condensation in a Catastrophically Cooling Solar Transition Region Looop

    Orange, N B; Oluseyi, H M; Hesterly, K; Patel, M; Champey, P R

    2015-01-01

    Minimal observational evidence exists for fast transition region (TR) upflows in the presence of cool loops. Observations of such occurrences challenge notions of standard solar atmospheric heating models, as well as their description of bright TR emission. Using the {\\it EUV Imaging Spectrometer} (EIS) onboard {\\it Hinode}, we observe fast upflows ($v_\\lambda$\\,$\\le$\\,$-$10 km s$^{-1}$) over multiple TR temperatures (5.8\\,$\\le$\\,$\\log T$\\,$\\le$ 6.0) at the footpoint sites of a cool loop ($\\log T$\\,$\\le$\\,6.0). Prior to cool loop energizing, asymmetric flows of $+$\\,5 km s$^{-1}$ and $-$\\,60 km s$^{-1}$ are observed at footpoint sites. These flows speeds and patterns occur simultaneously with both magnetic flux cancellation (at site of upflows only) derived from the {\\it Solar Dynamics Observatory}'s (SDOs) { \\it Helioseismic Magnetic Imager}'s (HMI) line-of-sight magnetogram images, and a 30\\% mass in-flux at coronal heights. The incurred non-equilibrium structure of the cool loop leads to a catastrophic coo...

  7. Rapid eye movement sleep deprivation induces an increase in acetylcholinesterase activity in discrete rat brain regions

    Benedito M.A.C.

    2001-01-01

    Full Text Available Some upper brainstem cholinergic neurons (pedunculopontine and laterodorsal tegmental nuclei are involved in the generation of rapid eye movement (REM sleep and project rostrally to the thalamus and caudally to the medulla oblongata. A previous report showed that 96 h of REM sleep deprivation in rats induced an increase in the activity of brainstem acetylcholinesterase (Achase, the enzyme which inactivates acetylcholine (Ach in the synaptic cleft. There was no change in the enzyme's activity in the whole brain and cerebrum. The components of the cholinergic synaptic endings (for example, Achase are not uniformly distributed throughout the discrete regions of the brain. In order to detect possible regional changes we measured Achase activity in several discrete rat brain regions (medulla oblongata, pons, thalamus, striatum, hippocampus and cerebral cortex after 96 h of REM sleep deprivation. Naive adult male Wistar rats were deprived of REM sleep using the flower-pot technique, while control rats were left in their home cages. Total, membrane-bound and soluble Achase activities (nmol of thiocholine formed min-1 mg protein-1 were assayed photometrically. The results (mean ± SD obtained showed a statistically significant (Student t-test increase in total Achase activity in the pons (control: 147.8 ± 12.8, REM sleep-deprived: 169.3 ± 17.4, N = 6 for both groups, P<0.025 and thalamus (control: 167.4 ± 29.0, REM sleep-deprived: 191.9 ± 15.4, N = 6 for both groups, P<0.05. Increases in membrane-bound Achase activity in the pons (control: 171.0 ± 14.7, REM sleep-deprived: 189.5 ± 19.5, N = 6 for both groups, P<0.05 and soluble enzyme activity in the medulla oblongata (control: 147.6 ± 16.3, REM sleep-deprived: 163.8 ± 8.3, N = 6 for both groups, P<0.05 were also observed. There were no statistically significant differences in the enzyme's activity in the other brain regions assayed. The present findings show that the increase in Achase activity

  8. EVOLUTION OF SPINNING AND BRAIDING HELICITY FLUXES IN SOLAR ACTIVE REGION NOAA 10930

    The line-of-sight magnetograms from Solar Optical Telescope Narrowband Filter Imager observations of NOAA Active Region 10930 have been used to study the evolution of spinning and braiding helicities over a period of five days starting from 2006 December 9. The north (N) polarity sunspot was the follower and the south (S) polarity sunspot was the leader. The N-polarity sunspot in the active region was rotating in the counterclockwise direction. The rate of rotation was small during the first two days of observations and it increased up to 8° hr–1 on the third day of the observations. On the fourth and fifth days it remained at 4° hr–1 with small undulations in its magnitude. The sunspot rotated about 260° in the last three days. The S-polarity sunspot did not complete more than 20° in five days. However, it changed its direction of rotation five times over a period of five days and injected both the positive and negative type of spin helicity fluxes into the corona. Through the five days, both the positive and negative sunspot regions injected equal amounts of spin helicity. The total injected helicity is predominantly negative in sign. However, the sign of the spin and braiding helicity fluxes computed over all the regions were reversed from negative to positive five times during the five-day period of observations. The reversal in spinning helicity flux was found before the onset of the X3.4-class flare, too. Though, the rotating sunspot has been observed in this active region, the braiding helicity has contributed more to the total accumulated helicity than the spinning helicity. The accumulated helicity is in excess of –7 × 1043 Mx2 over a period of five days. Before the X3.4-class flare that occurred on 2006 December 13, the rotation speed and spin helicity flux increased in the S-polarity sunspot. Before the flare, the total injected helicity was larger than –6 × 1043 Mx2. The observed reversal in the sign of spinning and braiding helicity

  9. Chandra X-ray observation of the HII region Gum 31 in the Carina Nebula complex

    Preibisch, T; Townsley, L; Broos, P; Ratzka, T

    2014-01-01

    (abridged) We used the Chandra observatory to perform a deep (70 ksec) X-ray observation of the Gum 31 region and detected 679 X-ray point sources. This extends and complements the X-ray survey of the central Carina nebula regions performed in the Chandra Carina Complex Project. Using deep near-infrared images from our recent VISTA survey of the Carina nebula complex, our Spitzer point-source catalog, and optical archive data, we identify counterparts for 75% of these X-ray sources. Their spatial distribution shows two major concentrations, the central cluster NGC 3324 and a partly embedded cluster in the southern rim of the HII region, but majority of X-ray sources constitute a rather homogeneously distributed population of young stars. Our color-magnitude diagram analysis suggests ages of ~1-2 Myr for the two clusters, whereas the distributed population shows a wider age range up to ~10 Myr. We also identify previously unknown companions to two of the three O-type members of NGC 3324 and detect diffuse X-ra...

  10. Pillars and globules at the edges of H ii regions, Confronting Herschel observations and numerical simulations

    Tremblin, P; Schneider, N; Audit, E; Hill, T; Didelon, P; Peretto, N; Arzoumanian, D; Motte, F; Zavagno, A; Bontemps, S; Anderson, L D; Andre, Ph; Bernard, J P; Csengeri, T; Di Francesco, J; Elia, D; Hennemann, M; Konyves, V; Marston, A P; Luong, Q Nguyen; Rivera-Ingraham, A; Roussel, H; Sousbie, T; Spinoglio, L; White, G J; Williams, J

    2013-01-01

    Pillars and globules are present in many high-mass star-forming regions, such as the Eagle nebula (M16) and the Rosette molecular cloud, and understanding their origin will help characterize triggered star formation. The formation mechanisms of these structures are still being debated. Recent numerical simulations have shown how pillars can arise from the collapse of the shell in on itself and how globules can be formed from the interplay of the turbulent molecular cloud and the ionization from massive stars. The goal here is to test this scenario through recent observations of two massive star-forming regions, M16 and Rosette. The column density structure of the interface between molecular clouds and H ii regions was characterized using column density maps obtained from far-infrared imaging of the Herschel HOBYS key programme. Then, the DisPerSe algorithm was used on these maps to detect the compressed layers around the ionized gas and pillars in different evolutionary states. Finally, their velocity structu...

  11. Type II supernovae as probes of environment metallicity: observations of host HII regions

    Anderson, J P; Dessart, L; Hamuy, M; Galbany, L; Morrell, N I; Stritzinger, M D; Phillips, M M; Folatelli, G; Boffin, H M J; de Jaeger, T; Kuncarayakti, H; Prieto, J L

    2016-01-01

    Spectral modelling of SNII atmospheres indicates a clear dependence of metal line strengths on progenitor metallicity. This motivates further work to evaluate the accuracy with which these SNe can be used as metallicity indicators. To assess this accuracy we present a sample of SNII HII-region spectroscopy, from which environment abundances are derived. These environment abundances are compared to the observed strength of metal lines in SN spectra. Combining our sample with measurements from the literature, we present oxygen abundances of 119 host HII regions, by extracting emission line fluxes and using abundance diagnostics. Then, following Dessart et al., these abundances are compared to equivalent widths of Fe 5018 A at various time and colour epochs. Our distribution of inferred SNII host HII-region abundances has a range of ~0.6 dex. We confirm the dearth of SNeII exploding at metallicities lower than those found (on average) in the Large Magellanic Cloud. The equivalent width of Fe 5018 A at 50 days po...

  12. Observed changes in phenology across the USA: A regional review for the 2013 National Climate Assessment, Southwest Regional Information Sheet

    Leicht-Young, Stacey A.; Enquist, Carolyn A.F.; Weltzin, Jake F.

    2013-01-01

    This is one in a series of eight, geographic region-focused information sheets that summarizes documented changes in plant and animal phenology over the past century across the United States. This summary is based on long-term studies (10 years or more) published in the primary scientific literature since 2001. A forthcoming manuscript synthesizes the findings of the eight regional information sheets.

  13. Observed changes in phenology across the USA: A regional review for the 2013 National Climate Assessment, Northeast Regional Information Sheet

    Leicht-Young, Stacey A.; Enquist, Carolyn A.F.; Weltzin, Jake F.

    2013-01-01

    This is one in a series of eight, geographic region-focused information sheets that summarizes documented changes in plant and animal phenology over the past century across the United States. This summary is based on long-term studies (10 years or more) published in the primary scientific literature since 2001. A forthcoming manuscript synthesizes the findings of the eight regional information sheets.

  14. Observed changes in phenology across the USA: A regional review for the 2013 National Climate Assessment, Southeast Regional Information Sheet

    Leicht-Young, Stacey A.; Enquist, Carolyn A.F.; Weltzin, Jake F.

    2013-01-01

    This is one in a series of eight, geographic region-focused information sheets that summarizes documented changes in plant and animal phenology over the past century across the United States. This summary is based on long-term studies (10 years or more) published in the primary scientific literature since 2001. A forthcoming manuscript synthesizes the findings of the eight regional information sheets.

  15. Observed changes in phenology across the USA: A regional review for the 2013 National Climate Assessment, Midwest Regional Information Sheet

    Leicht-Young, Stacey A.; Enquist, Carolyn A.F.; Weltzin, Jake F.

    2013-01-01

    This is one in a series of eight, geographic region-focused information sheets that summarizes documented changes in plant and animal phenology over the past century across the United States. This summary is based on long-term studies (10 years or more) published in the primary scientific literature since 2001. A forthcoming manuscript synthesizes the findings of the eight regional information sheets.

  16. The central pc-scale region in blazars: insights from multi-band observations

    Arshakian, Tigran G

    2014-01-01

    The empirical relations in the black hole-accretion disk-relativistic jet system and physical processes behind these relations are still poorly understood, partly because they operate close to the black hole within the central light year. Very long baseline array (VLBA) provides unparalleled resolution at 15 GHz with which to observe the jet components at sub-milliarcsecond scales, corresponding to sub-pc-scales for local blazars. We discuss the jet inner structure of blazars, location and radiation mechanisms operating in the innermost parsec-scale region of blazars, and evidence for jet-excited broad-line region (BLR) ouflowing downstream the jet. Outflowing BLR can provide necessary conditions for production of high energy emission along the jet between the base of the jet and the BLR and far beyond the BLR as evidenced by recent observations. Flat spectrum quasars and low synchrotron peaked sources are the most likely objects to host the outfllowing BLR. From the $\\gamma$-ray absorption arguments, we prop...

  17. Field lin topology in the dayside cusp region inferred from low altitude particle observations

    Dayside low altitude satellite observations of the pitch angle and energy distribution of electrons and protons in the energy range 1 keV to 100 keV during quiet geomagnetic conditions reveal that at times there is a clear latitudinal separation between the precipitating low energy (keV) electrons and protons, with the protons precipitating poleward of the electrons. The high energy (100keV) proton precipitation overlaps both the low energy electron and proton precipitation. These observations are consistent with a model where magnetosheath particles stream in along the cusp field lines and are at the same time convected poleward by an electric field. Electrons with energies of a few keV move fast and give the ''ionospheric footprint'' of the distant cusp. The protons are partly convected poleward of the cusp and into the polar cap. Here the mirroring protons populate the plasma mantle. Equatorward of the cusp the pitch angle distribution of both electrons and protons with energies above a few keV have a pancake shaped distribution indicating closed geomagnetic field lines. The 1 keV electrons penetrate into this region of closed field line structure maintaining an isotropic pitch angle distribution. The intensity is, however, reduced with respect to what it was in the cusp region. It is suggested that these electrons, the lowest measured on the satellite, are associated with the entry layer.(Auth.)

  18. Simulated high resolution observation by the sigma telescope of the low energy gamma-ray emission from the galactic center region based on recent observational results

    Simulated high resolution images of the galactic center region have been obtained for the SIGMA telescope, using recent observational data. It is shown, using various computing methods, that the next generation of gamma-ray imaging telescopes will be able to resolve this complex region of the sky

  19. 77 FR 24952 - Agency Information Collection Activities; Proposed Collection; Comment Request; Regional Haze...

    2012-04-26

    ... ICR (August 26, 2009; 74 FR 43118). The last collection request anticipated the program progressing... AGENCY Agency Information Collection Activities; Proposed Collection; Comment Request; Regional Haze... organizations and facilities potentially regulated under the regional haze rule. Title: Regional...

  20. ON MAGNETIC ACTIVITY BAND OVERLAP, INTERACTION, AND THE FORMATION OF COMPLEX SOLAR ACTIVE REGIONS

    McIntosh, Scott W. [High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307 (United States); Leamon, Robert J., E-mail: mscott@hao.ucar.edu [Department of Physics, Montana State University, Bozeman, MT 59717 (United States)

    2014-11-20

    Recent work has revealed a phenomenological picture of the how the ∼11 yr sunspot cycle of the Sun arises. The production and destruction of sunspots is a consequence of the latitudinal-temporal overlap and interaction of the toroidal magnetic flux systems that belong to the 22 yr magnetic activity cycle and are rooted deep in the Sun's convective interior. We present a conceptually simple extension of this work, presenting a hypothesis on how complex active regions can form as a direct consequence of the intra- and extra-hemispheric interaction taking place in the solar interior. Furthermore, during specific portions of the sunspot cycle, we anticipate that those complex active regions may be particularly susceptible to profoundly catastrophic breakdown, producing flares and coronal mass ejections of the most severe magnitude.

  1. Coronal energy input and dissipation in a solar active region 3D MHD model

    Bourdin, Philippe-A; Peter, Hardi

    2015-01-01

    Context. We have conducted a 3D MHD simulation of the solar corona above an active region in full scale and high resolution, which shows coronal loops, and plasma flows within them, similar to observations. Aims. We want to find the connection between the photospheric energy input by field-line braiding with the coronal energy conversion by Ohmic dissipation of induced currents. Methods. To this end we compare the coronal energy input and dissipation within our simulation domain above different fields of view, e.g. for a small loops system in the active region (AR) core. We also choose an ensemble of field lines to compare, e.g., the magnetic energy input to the heating per particle along these field lines. Results. We find an enhanced Ohmic dissipation of currents in the corona above areas that also have enhanced upwards-directed Poynting flux. These regions coincide with the regions where hot coronal loops within the AR core are observed. The coronal density plays a role in estimating the coronal temperatur...

  2. Examining the Magnetic Field Strength and the Horizontal and Vertical Motions in an Emerging Active Region

    Lin, Chia-Hsien

    2016-01-01

    Earlier observational studies have used the time evolution of emerging magnetic flux regions at the photosphere to infer their subsurface structures, assuming that the flux structure does not change significantly over the near-surface layer.In this study, we test the validity of this assumption by comparing the horizontal and vertical motions of an emerging active region. The two motions would be correlated if the emerging structure is rigid. The selected active region (AR) NOAA 11645 is not embedded in detectable preexisting magnetic field. The observed horizontal motion is quantified by the separation of the two AR polarities and the extension of the region. The vertical motion is derived from the magnetic buoyancy theory. Our results show that the separation of the polarities is fastest at the beginning with a velocity of $\\approx$~4~Mm hr$^{-1}$ and decreases to $\\le$~1~Mm hr$^{-1}$ after the main growing phase of flux emergence. The derived thick flux-tube buoyant velocity is between 1 and 3~Mm hr$^{-1}$...

  3. Forum for Arctic Modeling and Observational Synthesis (FAMOS): Past, current, and future activities

    Proshutinsky, A.; Steele, M.; Timmermans, M.-L.

    2016-06-01

    The overall goal of the Forum for Arctic Modeling and Observational Synthesis (FAMOS) community activities reported in this special issue is to enhance understanding of processes and mechanisms driving Arctic Ocean marine and sea ice changes, and the consequences of those changes especially in biogeochemical and ecosystem studies. Major 2013-2015 FAMOS accomplishments to date are: identification of consistent errors across Arctic regional models; approaches to reduce these errors, and recommendations for the most effective coupled sea ice-ocean models for use in fully coupled regional and global climate models. 2013-2015 FAMOS coordinated analyses include many process studies, using models together with observations to investigate: dynamics and mechanisms responsible for drift, deformation and thermodynamics of sea ice; pathways and mechanisms driving variability of the Atlantic, Pacific and river waters in the Arctic Ocean; processes of freshwater accumulation and release in the Beaufort Gyre; the fate of melt water from Greenland; characteristics of ocean eddies; biogeochemistry and ecosystem processes and change, climate variability, and predictability. Future FAMOS collaborations will focus on employing models and conducting observations at high and very high spatial and temporal resolution to investigate the role of subgrid-scale processes in regional Arctic Ocean and coupled ice-ocean and atmosphere-ice-ocean models.

  4. Storm activity in North Atlantic and precipitation anomalies in European region during winter seasons

    Vyazilova, N. A.; Vyazilova, A. E.

    2009-09-01

    The purpose of this paper is to show the storm activity influence on the formation of wet and dry zone in North Atlantic and European region during winter seasons 1994/95, 2006/07 and 2007/08 years with positive mode of NAO, 1995/96, 2000/01 and 2005/06 years with negative mode of NAO. The study of storm activity includes the analyses of cyclonic intensity and cyclone track number. Analyses of cyclonic intensity based on calculation cyclone centers number (CCN) and sum of cyclone centers MSLP anomalies (CCMA). This analyses based on automated cyclone tracking algorithm and the 6-hourly MSLP from the NCEP/NCAR reanalyses 2 from 1979 to 2009. Precipitation anomalies were calculated from CMAP archive. Analyses had included the calculation of cyclone track number in all region [30°N-80°N, 50°W-70°E]and selected latitude zone for long cyclones (with lifetime more 2 day) and short cyclones (with lifetime less 2 day). The study had shown the special features of CCN and CCMA patterns in region for long and short cyclones. The study shows, that every winter season short cyclone track number twice as much long cyclone track number. However, the contribution of long cyclones in main determines the CCMA in region. Study had shown that winter seasons with positive NAO mode Nord Europe were outstanding by strong positive precipitation anomalies and strong cyclonic intensity, and during winter seasons with negative NAO mode in this region were observed negative precipitation anomalies and weak cyclonic activity. Standartizide anomalies of integral CCMA for selected latitude zone [55°N-80°N, 50°W-70°E] had shown the intensification of cyclonic activity over North Atlantic and North European region in last years.

  5. TIDs in the Bottomside Ionospheric F-region Observed Near Jicamarca Using the TIDDBIT HF Doppler Sounder

    Crowley, G.; Chau, J. L.

    2012-12-01

    The equatorial ionosphere is the site of complex interactions between various geospace drivers, including thermospheric winds, electric fields, and tides propagating from below. Less well known is the effect of gravity waves, and their manifestation as traveling ionospheric disturbances (TIDs). HF Doppler sounders represent a low-cost and low-maintenance solution for monitoring wave activity in the F region ionosphere. Together with modern data analysis techniques, they can provide comprehensive TID characteristics, including both horizontal and vertical TID velocities and wavelengths across the entire spectrum from periods of 1 min to over an hour. In this invited talk, we review some of the previous observations of TIDs at low latitudes, and present new observations from the TIDDBIT HF Doppler Sounder recently developed by Atmospheric and Space Technology Research Associates LLC, and deployed at Jicamarca, Peru. The completeness of the wave information obtained from the TIDDBIT system makes it possible to reconstruct the vertical displacement of isoionic contours over the 200 km horizontal dimension of the sounder array, and movies revealing the detailed shape and motion of isoionic surfaces over Peru will be shown. We demonstrate how the TID characteristics in Peru vary with season and magnetic activity. We discuss their possible impact on triggering of ionospheric bubbles and irregularities. Such information will be relevant for various operational needs involving navigation, communication, and surveillance systems. Crowley G., and F.S. Rodrigues (2012), Characteristics of Traveling Ionospheric Disturbances Observed by the TIDDBIT Sounder, Radio Sci., doi:10.1029/2011RS004959.

  6. The "APEC Blue" phenomenon: Regional emission control effects observed from space

    Huang, Kan; Zhang, Xingying; Lin, Yanfen

    2015-10-01

    Observations from space were used to evaluate the effect of emission control measures on the changes of air pollutants in Beijing and its surroundings during the 2014 Asia-Pacific Economic Cooperation (APEC) Summit held in Beijing. Compared to the past three years (2011-2013), NO2 tropospheric vertical column densities in 2014 were found to exhibit almost across-the-board significant reductions over the North China Plain, suggesting the effectiveness of the national policy on NOx emission reduction during China's 12th "Five-Year-Plan". During the APEC period (Nov. 3-11), AOD and AAOD were found reduced the most in Beijing, followed by Hebei province. Stringent emission control measures implemented in Beijing and the regional joint control over the surroundings especially in Hebei were responsible for the good air quality and so-called "APEC Blue". However, air quality plummeted during the post-APEC period (Nov. 12-30), which was largely related to the lifting of local and regional joint emission control measures. By applying a spatial correlation analysis method, the potential emission source regions impacting air quality of Beijing included widespread areas in Hebei, Shandong, Shanxi, and Tianjin in the past three years (2011-2013). While during the study period in 2014, areas impacting Beijing evidently shrank and were limited within Hebei, suggesting evident effects of intense emission perturbations on lowering the extent of regional transport. This study indicates short-term measures did fix the air pollution problems in China but a permanent solution is still a tremendous challenge.

  7. Ozone Loss in the Antarctic Vortex Boundary Region from in situ Observations with the Geophysica Aircraft

    Ivanova, E.; Volk, C. M.; Riediger, O.; Strunk, M.; Schmidt, U.; Ulanovsky, A.; Ravegnani, F.; Redaelli, G.

    2003-04-01

    We analyse the distribution of ozone depletion in the Antarctic vortex edge region from in situ measurements taken from the Russian high-altitude aircraft M-55 "Geophysica" during the APE-GAIA campaign (Airborne Polar Experiment - Geophysica Aircraft In Antarctica) based out of Ushuaia, Argentina (54° S) in September and October 1999. The University of Frankfurt's High Altitude Gas Analyzer (HAGAR) provided in situ measurements of N2O, CFC-12, CFC-11, halon-1211 every 90 s, SF6 every 45 s, and CO2 every 10 s. Ozone was measured at high resolution by the Fast Ozone Analyzer (FOZAN). During 5 southbound flights toward the Antarctic vortex the Geophysica penetrated the vortex edge at various potential temperatures between 380 K and 480 K and performed dives inside the vortex yielding vertical profiles in one case down to the tropopause. The amount of lost ozone in the measured air has been estimated from the deviations from the compact extra-vortex O3-N2O relationship. While nearly complete ozone loss is found only in air clearly inside the vortex, ozone loss up to 60% is routinely found in a transition region extending 5° northward from the edge delineated by sharp meridional tracer gradients. We investigate whether this transition region lies indeed outside the vortex by applying alternative methods for defining the vortex edge, including potential vorticity and a new method using the observed relation of N2O with potential temperature (Greenblatt et al., J. Geophys. Res., 2002). We also examine the correlations between O3, CO2, and N2O to investigate the possibility that the decreased ozone within the transition region is caused by outward mixing from the vortex core.

  8. Quality of life at the dead sea region: the lower the better? an observational study

    Friger Michael

    2011-05-01

    Full Text Available Abstract Background The Dead Sea region, the lowest in the world at 410 meters below sea level, is considered a potent climatotherapy center for the treatment of different chronic diseases. Objective To assess the prevalence of chronic diseases and the quality of life of residents of the Dead Sea region compared with residents of the Ramat Negev region, which has a similar climate, but is situated 600 meters above sea level. Methods An observational study based on a self-administered questionnaire. Data were collected from kibbutz (communal settlement members in both regions. Residents of the Dead Sea were the study group and of Ramat Negev were the control group. We compared demographic characteristics, the prevalence of different chronic diseases and health-related quality of life (HRQOL using the SF-36 questionnaire. Results There was a higher prevalence of skin nevi and non-inflammatory rheumatic diseases (NIRD among Dead Sea residents, but they had significantly higher HRQOL mean scores in general health (68.7 ± 21 vs. 64.4 ± 22, p = 0.023 and vitality (64.7 ± 17.9 vs. 59.6 ± 17.3, p = 0.001, as well as significantly higher summary scores: physical component score (80.7 ± 18.2 vs. 78 ± 18.6, p = 0.042, and mental component score (79 ± 16.4 vs. 77.2 ± 15, p = 0.02. These results did not change after adjusting for social-demographic characteristics, health-related habits, and chronic diseases. Conclusions No significant difference between the groups was found in the prevalence of most chronic diseases, except for higher rates of skin nevi and NIRD among Dead Sea residents. HRQOL was significantly higher among Dead Sea residents, both healthy or with chronic disease.

  9. Altered cortical activation during action observation in amyotrophic lateral sclerosis patients: a parametric functional MRI study

    Li, Haiqing; Li, Yuxin; Yin, Bo; Tang, Weijun; Yu, Xiangrong; Geng, Daoying [Huashan Hospital, Department of Radiology, Fudan University, Shanghai (China); Chen, Yan [Fudan University, Department of Neurology, Huashan Hospital, Shanghai (China); Huang, Weiyuan [People' s Hospital of Hainan Province, Department of Radiology, Haikou, Hainan Province (China); Zhang, Biyun [Nanjing University of Traditional Chinese Medicine, Department of radiotherapy, Affiliated Jiangsu Province Hospital of Traditional Chinese Medicine, Nanjing (China)

    2015-09-15

    To investigate functional cerebral abnormalities in patients with amyotrophic lateral sclerosis (ALS) using functional magnetic resonance imaging (fMRI) during action observation. Thirty patients with ALS and 30 matched healthy controls underwent fMRI with an experimental paradigm while observing a video of repetitive flexion-extension of the fingers at three frequency levels or three complexity levels, alternated with periods of a static hand. A parametric analysis was applied to determine the effects of each of the two factors. Action observation activated similar neural networks as the research on execution of action in the ALS patients and healthy subjects in several brain regions related to the mirror-neuron system (MNS). In the ALS patients, in particular, the dorsal lateral premotor cortex (dPMC), inferior parietal gyrus (IPG), and SMA, were more activated compared with the activation in the controls. Increased activation within the primary motor cortex (M1), dPMC, inferior frontal gyrus (IFG), and superior parietal gyrus (SPG) mainly correlated with hand movement frequency/complexity in the videos in the patients compared with controls. The findings indicated an ongoing compensatory process occurring within the higher order motor-processing system of ALS patients, likely to overcome the loss of function. (orig.)

  10. Altered cortical activation during action observation in amyotrophic lateral sclerosis patients: a parametric functional MRI study

    To investigate functional cerebral abnormalities in patients with amyotrophic lateral sclerosis (ALS) using functional magnetic resonance imaging (fMRI) during action observation. Thirty patients with ALS and 30 matched healthy controls underwent fMRI with an experimental paradigm while observing a video of repetitive flexion-extension of the fingers at three frequency levels or three complexity levels, alternated with periods of a static hand. A parametric analysis was applied to determine the effects of each of the two factors. Action observation activated similar neural networks as the research on execution of action in the ALS patients and healthy subjects in several brain regions related to the mirror-neuron system (MNS). In the ALS patients, in particular, the dorsal lateral premotor cortex (dPMC), inferior parietal gyrus (IPG), and SMA, were more activated compared with the activation in the controls. Increased activation within the primary motor cortex (M1), dPMC, inferior frontal gyrus (IFG), and superior parietal gyrus (SPG) mainly correlated with hand movement frequency/complexity in the videos in the patients compared with controls. The findings indicated an ongoing compensatory process occurring within the higher order motor-processing system of ALS patients, likely to overcome the loss of function. (orig.)

  11. Eastern region represents a worrying cluster of active hepatitis C in Algeria in 2012.

    Bensalem, Aïcha; Selmani, Karima; Hihi, Narjes; Bencherifa, Nesrine; Mostefaoui, Fatma; Kerioui, Cherif; Pineau, Pascal; Debzi, Nabil; Berkane, Saadi

    2016-08-01

    Algeria is the largest country of Africa, peopled with populations living a range of traditional/rural and modern/urban lifestyles. The variations of prevalence of chronic active hepatitis care poorly known on the Algerian territory. We conducted a retrospective survey on all patients (n = 998) referred to our institution in 2012 and confirmed by us for an active hepatitis C. Half of the hepatitis C virus (HCV) isolates were genotyped. Forty Algerian regions out of the 48 were represented in our study. Three geographical clusters (Aïn-Temouchent/SidiBelAbbes, Algiers, and a large Eastern region) with an excess of active hepatitis C were observed. Patients coming from the Eastern cluster (Batna, Khenchela, Oum el Bouaghi, and Tebessa) were strongly over-represented (49% of cases, OR = 14.5, P hepatitis C epidemics are currently affecting Algerian population. The most worrying situation is observed in rural regions located east of Algeria. J. Med. Virol. 88:1394-1403, 2016. © 2016 Wiley Periodicals, Inc. PMID:26856380

  12. Poker Flat Incoherent Scatter Radar observations of anomalous electron heating in the E region

    Makarevich, R. A.; Koustov, A. V.; Nicolls, M. J.

    2013-07-01

    A comprehensive 2-year dataset collected with the Poker Flat Incoherent Scatter Radar (PFISR) located near Fairbanks, Alaska (MLAT = 65.4° N) is employed to identify and analyse 22 events of anomalous electron heating (AEH) in the auroral E region. The overall AEH occurrence probability is conservatively estimated to be 0.3% from nearly-continuous observations of the E region by PFISR, although it increases to 0.7-0.9% in the dawn and dusk sectors where all AEH events were observed. The AEH occurrence variation with MLT is broadly consistent with those of events with high convection velocity (>1000 m s-1) or electron temperature (> 800 K), except for much smaller AEH probability and absence of AEH events near magnetic midnight. This suggests that high convection electric field by itself is necessary but not sufficient for measurable electron heating by two-stream plasma waves. The multi-point observations are utilised to investigate the fundamental dependence of the electron temperature on the convection electric field, focusing on the previously-proposed saturation effects at extreme electric fields. The AEH dataset was found to exhibit considerable scatter and, on average, similar rate of the electron temperature increase with the electric field up to 100 mV m-1 as compared with previous studies. At higher (highest) electric fields, the electron temperatures are below the linear trend on average (within uncertainty). By employing a simple fluid model of AEH, it is demonstrated that some of this deviation from the linear trend may be due to a stronger vibrational cooling at very large temperatures and electric fields.

  13. "Smoking-Gun" Observables of Magnetic Reconnection: Spatiotemporal Evolution of Electron Characteristics Throughout the Diffusion Region

    Shuster, J. R.; Chen, L. J.; Bessho, N.; Li, G.; Torbert, R. B.; Wang, S.; Argall, M. R.; Daughton, W. S.

    2014-12-01

    Electron distribution functions can provide "smoking-gun" evidence for the detection of electron diffusion regions in collisionless magnetic reconnection. Knowledge of the spatiotemporal evolution of electron distributions during reconnection is significantly lacking, and will further elucidate the outstanding questions of how, where, and when electrons are energized during reconnection. Based on spacecraft observations and PIC simulations of symmetric reconnection, electrons in the inflow region are known to exhibit a temperature anisotropy Te// > Te⊥. Studies of exhaust electrons have reported hot and isotropic electrons, while others have reported anisotropic exhaust structures. Electron distributions in the vicinity of the X-line have a triangular, 3D velocity space structure with distinct striations corresponding to the number of times electrons reflect within the electron current layer. Here, we report the spatial and temporal evolution of electron distributions from the vicinity of the X-line to the end of the electron outflow jet, with the discovery that the discrete striations swirl and rotate as electrons re-magnetize, forming arc and ring structures. Highly structured, time-dependent electron anisotropy develops in the exhaust distributions only near or after the peak reconnection rate, explaining the previous discrepancy concerning the degree of electron anisotropy in the exhaust, and suggesting a technique to infer the evolution stage of reconnection using spacecraft measurements. We also present a theory for predicting the spacing of the striations of electron distributions in the vicinity of the X-line based on local measurements, which could be directly tested by spacecraft observations. Electron data from Cluster magnetotail reconnection inflows and exhausts exhibit many anisotropic structures as predicted by simulation. Observed distributions near the reconnection mid-plane (Bx ~ 0 nT) are often highly structured with populations exhibiting Te

  14. Silicon X-ray line emission from solar flares and active regions

    New observations of solar flare and active region X-ray spectra obtained with the Columbia University instrument on OSO-8 are presented and discussed. The high sensitivity of the graphite crystal panel has allowed both line and continuum spectra to be observed with moderate spectral resolution. Observations with higher spectral resolution have been made with a panel of pentaerythritol crystals. Twenty-nine lines between 1.5 and 7.0 A have been resolved and identified, including several dielectronic recombination satellite lines to Si XIV and Si XIII lines which have been observed for the first time. It has been found that thermal continuum models specified by single values of temperature and emission measure have fitted that data adequately, there being good agreement with the values of these parameters derived from line intensity ratios. (Auth.)

  15. The first X-ray imaging spectroscopy of quiescent solar active regions with NuSTAR

    Hannah, Iain G.; Grefenstette, Brian W.; Smith, David M.;

    2016-01-01

    We present the first observations of quiescent active regions (ARs) using the Nuclear Spectroscopic Telescope Array (NuSTAR), a focusing hard X-ray telescope capable of studying faint solar emission from high-temperature and non-thermal sources. We analyze the first directly imaged and spectrally...... resolved X-rays above 2 keV from non-flaring ARs, observed near the west limb on 2014 November 1. The NuSTAR X-ray images match bright features seen in extreme ultraviolet and soft X-rays. The NuSTAR imaging spectroscopy is consistent with isothermal emission of temperatures 3.1-4.4 MK and emission......, at least an order of magnitude stricter than previous limits. With longer duration observations and a weakening solar cycle (resulting in an increased livetime), future NuSTAR observations will have sensitivity to a wider range of temperatures as well as possible non-thermal emission....

  16. Interaction between an emerging flux region and a pre-existing fan-spine dome observed by IRIS and SDO

    Jiang, Fayu; Zhang, Jun; Yang, Shuhong

    2015-08-01

    We present multiwavelength observations of a fan-spine dome in the active region NOAA 11996 with the Interface Region Imaging Spectrograph (IRIS) and the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory (SDO) on 2014 March 9. The destruction of the fan-spine topology owing to the interaction between its magnetic fields and a nearby emerging flux region (EFR) is observed for the first time. The line-of-sight magnetograms from the Helioseismic and Magnetic Imager on board the SDO reveal that the dome is located on the mixed magnetic fields, with its rim rooted in the redundant positive polarity surrounding the minority parasitic negative fields. The fan surface of the dome consists of a filament system and recurring jets are observed along its spine. The jet occurring around 13:54 UT is accompanied by a quasi-circular ribbon that brightens in the clockwise direction along the bottom rim of the dome, which may indicate an occurrence of slipping reconnection in the fan-spine topology. The EFR emerges continuously and meets with the magnetic fields of the dome. Magnetic cancellations take place between the emerging negative polarity and the outer positive polarity of the dome's fields, which lead to the rise of the loop connecting the EFR and brightenings related to the dome. A single Gaussian fit to the profiles of the IRIS Si IV 1394 Å line is used in the analysis. It appears that there are two rising components along the slit, in addition to the rise in the line-of-sight direction. The cancellation process repeats again and again. Eventually the fan-spine dome is destroyed and a new connectivity is formed. We suggest that magnetic reconnection between the EFR and the magnetic fields of the fan-spine dome is responsible for the destruction of the dome.

  17. CALCULATING ENERGY STORAGE DUE TO TOPOLOGICAL CHANGES IN EMERGING ACTIVE REGION NOAA AR 11112

    The minimum current corona model provides a way to estimate stored coronal energy using the number of field lines connecting regions of positive and negative photospheric flux. This information is quantified by the net flux connecting pairs of opposing regions in a connectivity matrix. Changes in the coronal magnetic field, due to processes such as magnetic reconnection, manifest themselves as changes in the connectivity matrix. However, the connectivity matrix will also change when flux sources emerge or submerge through the photosphere, as often happens in active regions. We have developed an algorithm to estimate the changes in flux due to emergence and submergence of magnetic flux sources. These estimated changes must be accounted for in order to quantify storage and release of magnetic energy in the corona. To perform this calculation over extended periods of time, we must additionally have a consistently labeled connectivity matrix over the entire observational time span. We have therefore developed an automated tracking algorithm to generate a consistent connectivity matrix as the photospheric source regions evolve over time. We have applied this method to NOAA Active Region 11112, which underwent a GOES M2.9 class flare around 19:00 on 2010 October 16th, and calculated a lower bound on the free magnetic energy buildup of ∼8.25 × 1030 erg over 3 days.

  18. Calculating energy storage due to topological changes in emerging active region NOAA AR 11112

    Tarr, L A

    2012-01-01

    The Minimum Current Corona (MCC) model provides a way to estimate stored coronal energy using the number of field lines connecting regions of positive and negative photospheric flux. This information is quantified by the net flux connecting pairs of opposing regions in a connectivity matrix. Changes in the coronal magnetic field, due to processes such as magnetic reconnection, manifest themselves as changes in the connectivity matrix. However, the connectivity matrix will also change when flux sources emerge or submerge through the photosphere, as often happens in active regions. We have developed an algorithm to estimate the changes in flux due to emergence and submergence of magnetic flux sources. These estimated changes must be accounted for in order to quantify storage and release of magnetic energy in the corona. To perform this calculation over extended periods of time, we must additionally have a consistently labeled connectivity matrix over the entire observational time span. We have therefore develop...

  19. Regional Evaluation of ERA-40 Reanalysis Data with Marine Atmospheric Observations in the North Sea Area

    Nils H. Schade

    2013-12-01

    Full Text Available An important task of the departmental research programme KLIWAS is the evaluation and assessment of climate model results by means of a comprehensive reference data set. For validation purposes, and to create a North Sea wide maritime atmospheric and oceanographic reference database, in-situ observations of the Centre for Global Marine Meteorological Observations (GZS of the National Meteorological Service DWD have been compared to the ERA-40 reanalysis. ERA-40 is used as forcing for the hindcast runs of the ENSEMBLES regional climate models, which is used within the KLIWAS model chain. The GZS hosts a regularly updated, quality controlled, world-wide data bank of weather observations from the oceans. It includes data from all sorts of observation platforms as Voluntary Observing Ships (VOS, drifting and moored buoys, light vessels, and offshore platforms, either from real-time (RT via the Global Telecommunication System (GTS or from international exchange in delayed-mode (DM. In addition to the automated set of programs applied for high quality control, erroneous data are also manually corrected to a certain extent, if possible. To assure reliable statistics for the evaluation, the corrected observations are gridded to a resolution of 2.25 degree, so each grid box includes four ERA-40 reanalysis grid points. The temporal coverage of the grid boxes depends on shipping routes and the positions of automated systems. Observed air temperatures, covering a period of 40 years (1961?2000, show noticeable differences to the reanalysis data for all land influenced boxes, specifically in the winter months. The same differences can be found if ERA-40 data alone are compared between land- and sea facing boxes. They can not be found in GZS data. It can be assumed that the differences are not resulting from measurement errors or uncertain fraction variabilities, since they are small during the winter months. A comparison of the differences basing on the 1981

  20. Doppler shift of hot coronal lines in a moss area of an active region

    Dadashi, Neda; Tripathi, Durgesh; Solanki, Sami K; Wiegelmann, Thomas

    2012-01-01

    The moss is the area at the footpoint of the hot (3 to 5 MK) loops forming the core of the active region where emission is believed to result from the heat flux conducted down to the transition region from the hot loops. Studying the variation of Doppler shift as a function of line formation temperatures over the moss area can give clues on the heating mechanism in the hot loops in the core of the active regions. We investigate the absolute Doppler shift of lines formed at temperatures between 1 MK and 2 MK in a moss area within active region NOAA 11243 using a novel technique that allows determining the absolute Doppler shift of EUV lines by combining observations from the SUMER and EIS spectrometers. The inner (brighter and denser) part of the moss area shows roughly constant blue shift (upward motions) of 5 km/s in the temperature range of 1 MK to 1.6 MK. For hotter lines the blue shift decreases and reaches 1 km/s for Fe xv 284 {\\AA} (~2 MK). The measurements are discussed in relation to models of the hea...