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Sample records for active region temperature

  1. Density and Temperature Measurements in a Solar Active Region

    NASA Astrophysics Data System (ADS)

    Warren, Harry P.; Winebarger, Amy R.

    2003-10-01

    We present electron density and temperature measurements from an active region observed above the limb with the Solar Ultraviolet Measurements of Emitted Radiation spectrometer on the Solar and Heliospheric Observatory. Density-sensitive line ratios from Si VIII and S X indicate densities greater than 108 cm-3 as high as 200" (or 145 Mm) above the limb. At these heights, static, uniformly heated loop models predict densities close to 107 cm-3. Differential emission measure analysis shows that the observed plasma is nearly isothermal with a mean temperature of about 1.5 MK and a dispersion of about 0.2 MK. Both the differential emission measure and the Si XI/Si VIII line ratios indicate only small variations in the temperature at the heights observed. These measurements confirm recent observations from the Transition Region and Coronal Explorer of ``overdense'' plasma at temperatures near 1 MK in solar active regions. Time-dependent hydrodynamic simulations suggest that impulsive heating models can account for the large densities, but they have a difficult time reproducing the narrow range of observed temperatures. The observations of overdense, nearly isothermal plasma in the solar corona provide a significant challenge to theories of coronal heating.

  2. Temperature and density structure of a recurring active region jet

    NASA Astrophysics Data System (ADS)

    Mulay, Sargam M.; Zanna, Giulio Del; Mason, Helen

    2017-01-01

    Aims: We present a study of a recurring jet observed on October 31, 2011 by the Atmosphereic Imaging Assembly (AIA) on board the Solar Dynamic Observatory, the X-ray Telescope (XRT) and EUV Imaging Spectrometer (EIS) on board Hinode. We discuss the physical parameters of the jet that are obtained using imaging and spectroscopic observations, such as density, differential emission measure, peak temperature, velocity, and filling factor. Methods: A differential emission measure (DEM) analysis was performed at the region of the jet spire and the footpoint using EIS observations and also by combining AIA and XRT observations. The resulting EIS DEM curves were compared to those obtained with AIA-XRT. The DEM curves were used to create synthetic spectra with the CHIANTI atomic database. The predicted total count rates for each AIA channel were compared with the observed count rates. The effects of varying elemental abundances and the temperature range for the DEM inversion were investigated. Spectroscopic diagnostics were used to obtain an electron number density distribution for the jet spire and the jet footpoint. Results: The plasma along the line of sight in the jet spire and jet footpoint was found to be peak at 2.0 MK (log T [K] = 6.3). We calculated electron densities using the Fe XII (λ186/λ195) line ratio in the region of the spire (Ne = 7.6 × 1010 cm-3) and the footpoint (1.1 × 1011 cm-3). The plane-of-sky velocity of the jet is found to be 524 km s-1. The resulting EIS DEM values are in good agreement with those obtained from AIA-XRT. The synthetic spectra contributing to each AIA channel confirms the multi-thermal nature of the AIA channels in both regions. There is no indication of high temperatures, such as emission from Fe XVII (λ254.87) (log T [K] = 6.75) seen in the jet spire. In the case of the jet footpoint, synthetic spectra predict weak contributions from Ca XVII (λ192.85) and Fe XVII (λ254.87). With further investigation, we confirmed

  3. Average Potential Temperature of the Upper Mantle and Excess Temperatures Beneath Regions of Active Upwelling

    NASA Astrophysics Data System (ADS)

    Putirka, K. D.

    2006-05-01

    The question as to whether any particular oceanic island is the result of a thermal mantle plume, is a question of whether volcanism is the result of passive upwelling, as at mid-ocean ridges, or active upwelling, driven by thermally buoyant material. When upwelling is passive, mantle temperatures reflect average or ambient upper mantle values. In contrast, sites of thermally driven active upwellings will have elevated (or excess) mantle temperatures, driven by some source of excess heat. Skeptics of the plume hypothesis suggest that the maximum temperatures at ocean islands are similar to maximum temperatures at mid-ocean ridges (Anderson, 2000; Green et al., 2001). Olivine-liquid thermometry, when applied to Hawaii, Iceland, and global MORB, belie this hypothesis. Olivine-liquid equilibria provide the most accurate means of estimating mantle temperatures, which are highly sensitive to the forsterite (Fo) contents of olivines, and the FeO content of coexisting liquids. Their application shows that mantle temperatures in the MORB source region are less than temperatures at both Hawaii and Iceland. The Siqueiros Transform may provide the most precise estimate of TpMORB because high MgO glass compositions there have been affected only by olivine fractionation, so primitive FeOliq is known; olivine thermometry yields TpSiqueiros = 1430 ±59°C. A global database of 22,000 MORB show that most MORB have slightly higher FeOliq than at Siqueiros, which translates to higher calculated mantle potential temperatures. If the values for Fomax (= 91.5) and KD (Fe-Mg)ol-liq (= 0.29) at Siqueiros apply globally, then upper mantle Tp is closer to 1485 ± 59°C. Averaging this global estimate with that recovered at Siqueiros yields TpMORB = 1458 ± 78°C, which is used to calculate plume excess temperatures, Te. The estimate for TpMORB defines the convective mantle geotherm, and is consistent with estimates from sea floor bathymetry and heat flow (Stein and Stein, 1992), and

  4. Temperature structure of active regions deduced from helium-like sulphur lines

    NASA Technical Reports Server (NTRS)

    Watanabe, Tetsuya; Hara, Hirohisa; Shimizu, Toshifumi; Hiei, Eijiro; Bentley, Robert D.; Lang, James; Phillips, Kenneth J. H.; Pike, C. David; Fludra, Andrzej; Bromage, Barbara J. I.

    1995-01-01

    Solar active-region temperatures have been determined from the full-Sun spectra of helium-like sulfur (S XV) observed by the Bragg Crystal Spectrometer on Board the Yohkoh satellite. The average temperature deduced from S XV is demonstrated to vary with the solar activity level: A temperature of 2.5 x 10(exp 6) K is derived from the spectra taken during low solar activity, similar to the general corona, while 4 x 10(exp 6) K is obtained during a higher activity phase. For the latter, the high- temperature tail of the differential emission measure of active regions is found most likely due to the superposition of numerous flare-like events (micro/nano-flares).

  5. Temperature and Abundance Variations of an Active Region in Three Solar Rotations

    NASA Astrophysics Data System (ADS)

    Ko, Y.; Fludra, A.; Raymond, J. C.

    2002-12-01

    Active region 9718 (AR 9718) appeared at the east limb on November 26, 2001 which was newly formed when it was at the backside of the Sun. It survives through three solar rotations -- AR 9755 and AR 9798 for subsequent rotations. AR 9798 decayed to no visible sunspot before it reached the west limb. SOHO/UVCS observed this region four times, as part of SOHO JOP 151, when it was at the limbs (AR 9718 at the west limb, AR 9755 at both the east and west limbs, and AR 9798 at the west limb). SOHO/CDS made observations when AR 9718 and AR 9755 were at the west limb. We investigate the temperature and abundance variations of this active region during its lifetime, and look for possible correlations between these physical parameters and its magnetic characteristics.

  6. Seasonal and solar activity changes of electron temperature in the F-region and topside ionosphere

    NASA Astrophysics Data System (ADS)

    Sethi, N. K.; Pandey, V. K.; Mahajan, K. K.

    Incoherent scatter radar data from Arecibo, for high solar activity (HSA) (1989-1990) as well as for low solar activity (LSA) (1974-1977) periods, are used to study the seasonal and solar activity variations in electron temperature (Te) for noontime conditions. Inspite of large day-to-day variations, clear seasonal variations in average Te can be identified for both solar activity periods, with winter temperatures significantly higher in the topside (400-700 km) ionosphere. Further, comparison of average Te profiles for each season reveals distinct solar activity variations - a large increase in the F-region (200-350 km) Te, during summer and equinox as compared to winter, occurs as one moves from low to HSA. In the topside, however, electron temperature changes little with solar activity. Comparisons with IRI-95 and Truhlik et al. (2000) models show a reasonable agreement within one standard deviation of the measured values.

  7. Solar Dynamics Observatory Discovers Thin High Temperature Strands in Coronal Active Regions

    NASA Astrophysics Data System (ADS)

    Reale, Fabio; Guarrasi, Massimiliano; Testa, Paola; DeLuca, Edward E.; Peres, Giovanni; Golub, Leon

    2011-07-01

    One scenario proposed to explain the million degree solar corona is a finely stranded corona where each strand is heated by a rapid pulse. However, such fine structure has neither been resolved through direct imaging observations nor conclusively shown through indirect observations of extended superhot plasma. Recently, it has been shown that the observed difference in the appearance of cool and warm coronal loops (~1 MK and ~2-3 MK, respectively)—warm loops appearing "fuzzier" than cool loops—can be explained by models of loops composed of subarcsecond strands, which are impulsively heated up to ~10 MK. That work predicts that images of hot coronal loops (gsim 6 MK) should again show fine structure. Here we show that the predicted effect is indeed widely observed in an active region with the Solar Dynamics Observatory, thus supporting a scenario where impulsive heating of fine loop strands plays an important role in powering the active corona.

  8. Adult activity and temperature preference drives region-wide damselfly (Zygoptera) distributions under a warming climate

    PubMed Central

    Corser, Jeffrey D.; White, Erin L.; Schlesinger, Matthew D.

    2015-01-01

    We analysed a recently completed statewide odonate Atlas using multivariate linear models. Within a phylogenetically explicit framework, we developed a suite of data-derived traits to assess the mechanistic distributional drivers of 59 species of damselflies in New York State (NYS). We found that length of the flight season (adult breeding activity period) mediated by thermal preference drives regional distributions at broad (105 km2) scales. Species that had longer adult flight periods, in conjunction with longer growing seasons, had significantly wider distributions. These intrinsic traits shape species' responses to changing climates and the mechanisms behind such range shifts are fitness-based metapopulation processes that adjust phenology to the prevailing habitat and climate regime through a photoperiod filter. PMID:25878048

  9. Traveling planetary wave activity from mesopause region airglow temperatures determined by the Network for the Detection of Mesospheric Change (NDMC)

    NASA Astrophysics Data System (ADS)

    Reisin, E. R.; Scheer, J.; Dyrland, M. E.; Sigernes, F.; Deehr, C. S.; Schmidt, C.; Höppner, K.; Bittner, M.; Ammosov, P. P.; Gavrilyeva, G. A.; Stegman, J.; Perminov, V. I.; Semenov, A. I.; Knieling, P.; Koppmann, R.; Shiokawa, K.; Lowe, R. P.; López-González, M. J.; Rodríguez, E.; Zhao, Y.; Taylor, M. J.; Buriti, R. A.; Espy, P. J.; French, W. J. R.; Eichmann, K.-U.; Burrows, J. P.; von Savigny, C.

    2014-11-01

    The global distribution of traveling planetary wave (PW) activity in the mesopause region is estimated for the first time from ground-based airglow measurements. Monthly and total mean climatologies of PW power are determined from rotational temperatures measured at 19 sites from 78° N to 76° S which contribute to the Network for the Detection of Mesospheric Change (NDMC). Wave power is expressed as the standard deviation of nocturnal mean temperature around the seasonal temperature variation. The results from 20° N confirm the SABER traveling PW proxy by Offermann et al. (2009, J. Geophys. Res. 114, D06110) at two altitudes. Most sites between 69° S and 69° N show total mean traveling PW activity of about 6 K, and only some high latitude sites have considerably higher activity levels. At the two tropical sites, there is practically no seasonal variation of PW activity. At 70% of the midlatitude sites, the seasonal variation is moderate for most of the year, but it is quite appreciable at all high latitude sites. Results about traveling PW activity at 87 km and 95 km available from several sites signal similar behavior at both altitudes. The total mean climatological results here obtained have further been used to separate the traveling PW contribution from the superposition of wave types contained in OH rotational temperature fluctuations measured by the SCIAMACHY instrument on Envisat. A narrow equatorial wave activity maximum is probably caused by gravity waves, while a tendency towards greater activity at higher northern latitudes may be due to stationary planetary waves.

  10. Regional and total body active heating and cooling of a resting diver in water of varied temperatures

    NASA Astrophysics Data System (ADS)

    Bardy, Erik; Mollendorf, Joseph; Pendergast, David

    2008-02-01

    Passive insulations alone are not sufficient for maintaining underwater divers in thermal balance or comfort. The purpose of this study was to experimentally determine the active heating and cooling requirements to keep a diver at rest in thermal balance and comfort in water temperatures between 10 and 40 °C. A diver wearing a prototype tubesuit and a wetsuit (3 or 6.5 mm foam neoprene) was fully submersed (0.6 m) in water at a specified temperature (10, 20, 30 and 40 °C). During immersion, the tubesuit was perfused with 30 °C water at a flow rate of 0.5 L min-1 to six individual body regions. An attempt was made to keep skin temperatures below 42 °C in hot water (>30 °C) and elevated but below 32 °C in cold water (<20 °C). A skin temperature of 32 °C is the threshold for maximal body thermal resistance due to vasoconstriction. Skin temperatures and core temperature were monitored during immersion to ensure they remained within set thermal limits. In addition skin heat flux, oxygen consumption and the thermal exchange of the tubesuit were measured. In both wetsuit thicknesses there was a linear correlation between the thermal exchange of the tubesuit and ambient water temperature. In the 6.5 mm wetsuit -214 W to 242 W of heating (-) and cooling (+) was necessary in 10 °C to 40 °C water, respectively. In the 3 mm wetsuit -462 to 342 W was necessary in 10 °C to 40 °C water, respectively. It was therefore concluded that a diver at rest can be kept in thermal balance in 10-40 °C water with active heating and cooling.

  11. Room-temperature lasing in microring cavities with an InAs/InGaAs quantum-dot active region

    SciTech Connect

    Kryzhanovskaya, N. V. Zhukov, A. E.; Nadtochy, A. M.; Maximov, M. V.; Moiseev, E. I.; Kulagina, M. M.; Savelev, A. V.; Arakcheeva, E. M.; Lipovskii, A. A.; Zubov, F. I.; Kapsalis, A.; Mesaritakis, C.; Syvridis, D.; Mintairov, A.; Livshits, D.

    2013-10-15

    Microring cavities (diameter D = 2.7-7 {mu}m) with an active region based on InAs/InGaAs quantum dots are fabricated and their characteristics are studied by the microphotoluminescence method and near-field optical microscopy. A value of 22 000 is obtained for the Q factor of a microring cavity with the diameter D = 6 {mu}m. Lasing up to room temperature is obtained in an optically pumped ring microlaser with a diameter of D = 2.7 {mu}m.

  12. Active Region Loops: Temperature Measurements as a Function of Time from Joint TRACE and SOHO CDS Observations

    NASA Astrophysics Data System (ADS)

    Cirtain, J. W.; Del Zanna, G.; DeLuca, E. E.; Mason, H. E.; Martens, P. C. H.; Schmelz, J. T.

    2007-01-01

    In this paper, we aim to quantitatively investigate the structure and time variation of quiescent active region loop structures. We coordinated a joint program of observations (JOP 146) using TRACE, to obtain high-cadence EUV images, and SOHO CDS, to obtain spectroscopic data. Loop intensities are used to determine temperature as a function of time for a single loop, taking full account of the background emission. In many locations, the emission measure loci are consistent with an isothermal structure. However, the results indicate significant changes in the loop temperature (between 1 and 2 MK) over the 6 hr observing period. It is possible that the loop structures are composed of multiple, independently heated strands with sizes less than the resolution of the imager and spectrometer.

  13. Temperature dependence of emission measure in solar X-ray plasmas. 1: Non-flaring active regions

    NASA Technical Reports Server (NTRS)

    Phillips, K. J. H.

    1974-01-01

    X-ray and ultraviolet line emission from hot, optically thin material forming coronal active regions on the sun may be described in terms of an emission measure distribution function, Phi (T). A relationship is developed between line flux and Phi (T), a theory which assumes that the electron density is a single-valued function of temperature. The sources of error involved in deriving Phi (T) from a set of line fluxes are examined in some detail. These include errors in atomic data (collisional excitation rates, assessment of other mechanisms for populating excited states of transitions, element abundances, ion concentrations, oscillator strengths) and errors in observed line fluxes arising from poorly - known instrumental responses. Two previous analyses are discussed in which Phi (T) for a non-flaring active region is derived. A least squares method of Batstone uses X-ray data of low statistical significance, a fact which appears to influence the results considerably. Two methods for finding Phi (T) ab initio are developed. The coefficients are evaluated by least squares. These two methods should have application not only to active-region plasmas, but also to hot, flare-produced plasmas.

  14. Effects of acute microinjections of thyroid hormone to the preoptic region of hypothyroid adult male rats on sleep, motor activity and body temperature.

    PubMed

    Moffett, Steven X; Giannopoulos, Phillip F; James, Thomas D; Martin, Joseph V

    2013-06-21

    Thyroid hormones induce short-latency nongenomic effects in adult brain tissue, suggesting that their acute administration would affect brain activity in intact animals. The influence on EEG-defined sleep of acute restoration of l-3,3'5-triiodothyronine (T3) to a sleep-regulatory brain region, the preoptic region, was examined in hypothyroid rats. Sleep parameters were monitored for 48 h weekly: for 24 h immediately following a control microinjection and for an additional 24h after a second microinjection including a T3 dose to the preoptic region or lateral ventricle. Male albino rats were implanted with EEG and EMG electrodes, abdominal temperature/activity transponders and unilateral lateral ventricle cannulae or bilateral preoptic region cannulae, and were given 0.02% n-propythiouracil (PTU) in their drinking water for 4 weeks. For histologically-confirmed bilateral preoptic region cannula placements (N=7), effects of T3 (especially a 3 μg dose) were apparent within 10h of injection as decreases in REM, NREM and total sleep and increases in waking and activity. Minimal effects of lateral ventricle T3 microinjection were demonstrated (N=5). Significant effects due to the time of day on the experimental measures were seen in both lateral ventricle and preoptic region groups, but these effects did not interact with the effect of administered hormone dose. These effects of T3 microinjection to the preoptic region were demonstrated after acute injections and within hours of injection rather than after chronic administration over days.

  15. Active region seismology

    NASA Technical Reports Server (NTRS)

    Bogdan, Tom; Braun, D. C.

    1995-01-01

    Active region seismology is concerned with the determination and interpretation of the interaction of the solar acoustic oscillations with near-surface target structures, such as magnetic flux concentration, sunspots, and plage. Recent observations made with a high spatial resolution and a long temporal duration enabled measurements of the scattering matrix for sunspots and solar active regions to be carried out as a function of the mode properties. Based on this information, the amount of p-mode absorption, partial-wave phase shift, and mode mixing introduced by the sunspot, could be determined. In addition, the possibility of detecting the presence of completely submerged magnetic fields was raised, and new procedures for performing acoustic holography of the solar interior are being developed. The accumulating evidence points to the mode conversion of p-modes to various magneto-atmospheric waves within the magnetic flux concentration as being the unifying physical mechanism responsible for these diverse phenomena.

  16. Active Region Soft X-Ray Spectra and Temperature Analyses based on Sounding Rocket Measurements from the Solar Aspect Monitor (SAM), - a Modified SDO/EVE Instrument

    NASA Astrophysics Data System (ADS)

    Didkovsky, Leonid V.; Wieman, Seth; Woods, Thomas N.; Jones, Andrew; Moore, Christopher

    2016-05-01

    Some initial results of soft x-ray spectral (0.5 to 3.0 nm) observations of active regions (AR11877 and AR11875) from a sounding rocket flight NASA 36.290 on 21 October 2013 at about 18:30 UT are reported. These observations were made by a Solar Aspect Monitor (SAM), a rocket version of the EUV Variability Experiment’s (EVE) channel, a pinhole camera modified for EVE rocket suite of instruments to include a free-standing transmission grating (200 nm period), which provided spectrally-resolved images of the solar disk. Intensity ratios for strong emission lines extracted from temporally averaged SAM spectral profiles of the ARs were compared to appropriately convolved modeled CHIANTI spectra. These ratios represent the AR’s temperature structures, which are compared to the structures derived from some other observations and temperature models.

  17. Fiber optic wide region temperature sensing system

    NASA Astrophysics Data System (ADS)

    Xu, Xunjian; Nonaka, Koji; Song, Hongbin

    2008-12-01

    A fiber optic wide region temperature sensing system based on optical pulse correlation measurement and SHG differential detection technique is proposed and demonstrated. In order to establish the reliability of this fiber optic temperature sensing system, a long-term wide region outside temperature monitoring experiment with a new designed 20ps time-bias optical pulse correlation unit for wide measurement rang was carried out. The temperature measured by means of a correlation sensor had the same variation as and higher sensitivity and quick measurement response than the digital thermometer. The resolution of the correlation sensor is approximately +/-0.01 oC . This fiber optic temperature sensor can measure even in very tough environment and low and high temperature range. Not only point temperature but also a field area average temperature can monitor by this system.

  18. 3D-Stereoscopic Analysis of Solar Active Region Loops: I: SoHo/EIT Observations at Temperatures of 1.0-1.5 MK

    NASA Technical Reports Server (NTRS)

    Aschwanden, Markus J.; Newmark, Jeff; Delaboudiniere, Jean-Pierre; Neupert, Werner M.; Portier-Fozzani, Fabrice; Gary, G. Allen; Zucker, Arik

    1998-01-01

    The three-dimensional (3D) structure of solar active region NOAA 7986 observed on 1996 August 30 with the Extrem-ultraviolet Imaging Telescope (EIT) onboard the Solar and Heliospheric Observatory (SoHO) is analyzed. We develop a new method of Dynamic Stereoscopy to reconstruct the 3D geometry of dynamically changing loops, which allows us to determine the orientation of the loop plane with respect to the line-of-sight, a prerequisite to correct properly for projection effects in 3D loop models. With this method and the filter-ratio technique applied to EIT 171 A and 195 A images we determine the 3D coordinates (x(s), y(s), z(s)), the loop width) w(s), the electron density n(sub e)(s), and the electron temperature T(sub e)(s) as function of the loop length s for 30 loop segments. Fitting the loop densities with an exponential density model n(sub e)(h) we find that the so inferred scale height temperatures, T(sub e)(sup lambda) = 1.22 +/- 0.23 MK, match closely the EIT filter-ratio temperatures, T(sub e)(sup FIT) = 1.21 +/- 0.06 MK. We conclude that these rather large-scale loops (with heights of h approx. equals 50 - 200 Mm) that dominate EIT 171 A images are close to thermal equilibrium. Most of the loops show no significant thickness variation w(s), but many exhibit a trend of increasing temperature (dT/ds greater than 0) above the footpoint.

  19. Solar active region display system

    NASA Astrophysics Data System (ADS)

    Golightly, M.; Raben, V.; Weyland, M.

    2003-04-01

    The Solar Active Region Display System (SARDS) is a client-server application that automatically collects a wide range of solar data and displays it in a format easy for users to assimilate and interpret. Users can rapidly identify active regions of interest or concern from color-coded indicators that visually summarize each region's size, magnetic configuration, recent growth history, and recent flare and CME production. The active region information can be overlaid onto solar maps, multiple solar images, and solar difference images in orthographic, Mercator or cylindrical equidistant projections. Near real-time graphs display the GOES soft and hard x-ray flux, flare events, and daily F10.7 value as a function of time; color-coded indicators show current trends in soft x-ray flux, flare temperature, daily F10.7 flux, and x-ray flare occurrence. Through a separate window up to 4 real-time or static graphs can simultaneously display values of KP, AP, daily F10.7 flux, GOES soft and hard x-ray flux, GOES >10 and >100 MeV proton flux, and Thule neutron monitor count rate. Climatologic displays use color-valued cells to show F10.7 and AP values as a function of Carrington/Bartel's rotation sequences - this format allows users to detect recurrent patterns in solar and geomagnetic activity as well as variations in activity levels over multiple solar cycles. Users can customize many of the display and graph features; all displays can be printed or copied to the system's clipboard for "pasting" into other applications. The system obtains and stores space weather data and images from sources such as the NOAA Space Environment Center, NOAA National Geophysical Data Center, the joint ESA/NASA SOHO spacecraft, and the Kitt Peak National Solar Observatory, and can be extended to include other data series and image sources. Data and images retrieved from the system's database are converted to XML and transported from a central server using HTTP and SOAP protocols, allowing

  20. Regional Activities Division. Papers.

    ERIC Educational Resources Information Center

    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…

  1. Active Region Release Two CMEs

    NASA Video Gallery

    Solar material can be seen blowing off the sun in this video captured by NASA’s Solar Dynamics Observatory (SDO) on the night of Feb. 5, 2013. This active region on the sun sent out two coronal ...

  2. Evaluation of the Absolute Regional Temperature Potential

    NASA Technical Reports Server (NTRS)

    Shindell, D. T.

    2012-01-01

    The Absolute Regional Temperature Potential (ARTP) is one of the few climate metrics that provides estimates of impacts at a sub-global scale. The ARTP presented here gives the time-dependent temperature response in four latitude bands (90-28degS, 28degS-28degN, 28-60degN and 60-90degN) as a function of emissions based on the forcing in those bands caused by the emissions. It is based on a large set of simulations performed with a single atmosphere-ocean climate model to derive regional forcing/response relationships. Here I evaluate the robustness of those relationships using the forcing/response portion of the ARTP to estimate regional temperature responses to the historic aerosol forcing in three independent climate models. These ARTP results are in good accord with the actual responses in those models. Nearly all ARTP estimates fall within +/-20%of the actual responses, though there are some exceptions for 90-28degS and the Arctic, and in the latter the ARTP may vary with forcing agent. However, for the tropics and the Northern Hemisphere mid-latitudes in particular, the +/-20% range appears to be roughly consistent with the 95% confidence interval. Land areas within these two bands respond 39-45% and 9-39% more than the latitude band as a whole. The ARTP, presented here in a slightly revised form, thus appears to provide a relatively robust estimate for the responses of large-scale latitude bands and land areas within those bands to inhomogeneous radiative forcing and thus potentially to emissions as well. Hence this metric could allow rapid evaluation of the effects of emissions policies at a finer scale than global metrics without requiring use of a full climate model.

  3. The 17 GHz active region number

    SciTech Connect

    Selhorst, C. L.; Pacini, A. A.; Costa, J. E. R.; Giménez de Castro, C. G.; Valio, A.; Shibasaki, K.

    2014-08-01

    We report the statistics of the number of active regions (NAR) observed at 17 GHz with the Nobeyama Radioheliograph between 1992, near the maximum of cycle 22, and 2013, which also includes the maximum of cycle 24, and we compare with other activity indexes. We find that NAR minima are shorter than those of the sunspot number (SSN) and radio flux at 10.7 cm (F10.7). This shorter NAR minima could reflect the presence of active regions generated by faint magnetic fields or spotless regions, which were a considerable fraction of the counted active regions. The ratio between the solar radio indexes F10.7/NAR shows a similar reduction during the two minima analyzed, which contrasts with the increase of the ratio of both radio indexes in relation to the SSN during the minimum of cycle 23-24. These results indicate that the radio indexes are more sensitive to weaker magnetic fields than those necessary to form sunspots, of the order of 1500 G. The analysis of the monthly averages of the active region brightness temperatures shows that its long-term variation mimics the solar cycle; however, due to the gyro-resonance emission, a great number of intense spikes are observed in the maximum temperature study. The decrease in the number of these spikes is also evident during the current cycle 24, a consequence of the sunspot magnetic field weakening in the last few years.

  4. Fall of Global Temperature In The First Half of 21-st Century. Physical-statistical Modeling of Global and Regional Annual Surface Temperatures of Air On The Basis of Energy Model of Atmosphere and Hydrosphere In View of Solar Activity.

    NASA Astrophysics Data System (ADS)

    Boudovyi, V.; Medvedev, V.; Khorozov, S.; Belogolov, V.

    The energy model of atmosphere and hydrosphere and model of global annual surface temperatures are constructed on the basis of the equations of thermal balance of the upper layers of the Earth. It is supposed, that a major reason of greenhouse effect is the increase of concentration of products of water vapour condensation (sublimation) on account of ionization of the upper layers of an atmosphere by hard radiation at high solar activity. Parameters of the models were defined on the basis of a 300-years observation series of Wolf numbers and 120-years observation series of global annual temperature. The models of annual surface temperatures in various geographical points are constructed on the basis of energy model of the upper layers of the Earth and 50- years series of meteorological observations. The models of annual surface temperatures well explain the global warming during the 20-th century and annual temperature oscillations on a phon of warming trend. The modelling of annual surface temperature changings within several centuries (on the basis of the probable script of solar activity development) shows, that in the first half of the 21-st century global warming, probably, will be replaced by the fall of global temperature. At the end of the 22-nd century this tendency can finish by small glacial period similar to period observed in Europe in 15-18 centuries and most brightly expressed during 1450 -1700 years. The analysis of probable consequences of fall of temperature in Europe on the basis of historical documents is submitted.

  5. SDO Sees Active Region Outbursts

    NASA Video Gallery

    This close up video by NASA’s Solar Dynamics Observatory shows an active region near the right-hand edge of the sun’s disk, which erupted with at least a dozen minor events over a 30-hour period fr...

  6. Decay of Solar Active Regions

    NASA Technical Reports Server (NTRS)

    Hathaway, David H.; Choudhary, Debi Prasad

    2005-01-01

    We examine the record of sunspot group areas observed over a period of 100 years to determine the rate of decay of solar active regions. We exclude observations of groups when they are more than 60deg in longitude from the central meridian and only include data when at least three days of observations are available following the date of maximum area for a spot group's disk passage. This leaves data for some 24,000 observations of active region decay. We find that the decay rate is a constant 20 microHem/day for spots smaller than about 200 microHem (about the size of a supergranule). This decay rate increases linearly to about 90 microHem/day for spots with areas of 1000 microHem. We find no evidence for significant variations in active region decay from one solar cycle to another. However, we do find that the decay rate is slower at lower latitudes. This gives a slower decay rate during the declining phase of sunspot cycles.

  7. Brazil's sugarcane boom could affect regional temperatures

    NASA Astrophysics Data System (ADS)

    Schultz, Colin

    2013-04-01

    With the world seeking to cut its dependence on fossil fuels, the use of bioethanol and other biofuels is on the rise. In Brazil, the second largest producer and consumer of bioethanol, this has led to a boom in sugarcane production. Based on new laws and trade agreements, researchers expect Brazil's production of sugarcane-derived ethanol to increase tenfold over the next decade, with considerable land being converted for growing sugarcane. Much of this expansion is expected to come at a loss of some of the country's cerrado savannas. So while a major aim of the turn to biofuels is to reduce the transfer of carbon to the atmosphere and mitigate global climate change, the shifting agricultural activity could have direct consequences on Brazil's climate by changing the region's physical and biogeochemical properties.

  8. EUV Observations of Active Region Dynamics

    NASA Astrophysics Data System (ADS)

    Deluca, E. E.; Cirtain, J. W.; del Zanna, G.; Mason, H. E.; Martens, P. C.; Schmelz, J.; Golub, L.

    2005-05-01

    Data collected during SoHO JOP 146, in collaboration with TRACE, is used to investigate the physical characteristics of coronal active region loops as a function of time and position along and across loop structures. These data include TRACE images in all three EUV passbands, and simultaneous CDS spectroscopic observations. Preliminary measurements of the loop temperature both along the loop half-length and loop cross-section are presented as a function of time. We will show the temperature and density profiles of several structures as a function of position, show changes in temperature and density with time and characterize the coronal background emission. Questions raised by these results will be greatly advanced with the high resolution spectra available from the EIS on Solar-B.

  9. Solar turbulence in earth's global and regional temperature anomalies.

    PubMed

    Scafetta, Nicola; Grigolini, Paolo; Imholt, Timothy; Roberts, Jim; West, Bruce J

    2004-02-01

    This paper presents a study of the influence of solar activity on the earth's temperature. In particular, we focus on the repercussion of the fluctuations of the solar irradiance on the temperature of the Northern and Southern hemispheres as well as on land and ocean regions. While solar irradiance data are not directly analyzed, we make use of a published solar irradiance reconstruction for long-time-scale fluctuations, and for short-time-scale fluctuations we hypothesize that solar irradiance and solar flare intermittency are coupled in such a way that the solar flare frequency fluctuations are stochastically equivalent to those of the solar irradiance. The analysis is based upon wavelet multiresolution techniques and scaling analysis methods for processing time series. The limitations of the correlation analysis applied to the short-time-scale fluctuations are discussed. The scaling analysis uses both the standard deviation and the entropy of the diffusion generated by the temperature signals. The joint use of these two scaling methods yields evidence of a Lévy component in the temporal persistence of the temperature fluctuations within the temporal range from a few weeks to a few years. This apparent Lévy persistence of the temperature fluctuations is found, by using an appropriate model, to be equivalent to the Lévy scaling of the solar flare intermittency. The mean monthly temperature data sets cover the period from 1856 to 2002.

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

    NASA Astrophysics Data System (ADS)

    Zangrilli, L.; Poletto, G.

    2016-10-01

    Context. 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. Aims: 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. Methods: 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⊙, 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 Lyα line and the O vi doublet lines at 1031.9 and 1037.6 Å. Results: 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 types of outflows at different latitudes, both possibly originating in the same negative polarity area of the AR. We also analyzed the behavior of the Si xii 520 Å line along the UVCS slit in an attempt to reveal changes in the Si abundance when different regions are traversed. Although we found some evidence for a Si enrichment in the AR outflows, alternative interpretations are also plausible. Conclusions: Our results demonstrate that outflows from ARs are detectable in the intermediate corona throughout the whole AR lifetime. This confirms that outflows contribute to the slow wind.

  11. The evolution of active region loop plasma

    NASA Technical Reports Server (NTRS)

    Krall, K. R.; Antiochos, S. K.

    1980-01-01

    The adjustment of coronal active-region loops to changes in their heating rate is investigated numerically. The one-dimensional hydrodynamic equations are solved subject to boundary conditions in which heat flux-induced mass exchange between coronal and chromospheric components is allowed. The calculated evolution of physical parameters suggests that (1) mass supplied during chromospheric evaporation is much more effective in moderating coronal temperature excursions than when downward heat flux is dissipated by a static chromosphere, and (2) the method by which the chromosphere responds to changing coronal conditions can significantly influence coronal readjustment time scales. Observations are cited which illustrate the range of possible fluctuations in the heating rates.

  12. Changes in Soil Temperature Regimes under Regional Climate Change

    NASA Astrophysics Data System (ADS)

    Millar, S. W.

    2013-12-01

    Soil temperatures can provide a smoothed record of regional changes in atmospheric conditions due to soil thermal properties that reduce the annual air and surface temperature amplitude. In areas with seasonal snow cover, however, its insulating effect isolates the soil thermal regime from winter air temperatures. Under changing regional climate patterns, snow cover extent, depth and duration are decreasing. The net effect is thus an expected winter cooling of soil temperature. However, the extent to which this might be mitigated by warmer summer conditions, and changing soil moisture remains to be seen. To examine the relative strength of a cold-season cooling signal versus enhanced summer warming, a network of soil temperature loggers has recorded hourly soil temperatures over the period 2005-2013 within a single watershed experiencing 'lake effect snow'. Elevations range from 168 m to 612 m, on Silurian and Ordovician shale, limestone, and sandstone that have been heavily glaciated. Most of the sites are located on NY Department of Environmental Conservation land in mixed, hardwood and spruce forests. At six sites in varied topographic and land-use setting, two ONSET HOBO Outdoor 4 channel soil temperature loggers are deployed in order to reduce concerns of data reliability and systematic logger drift. Five sites also record air temperature using HOBO Pro Series Temperature loggers at three sites and HOBO Weather Stations at two. Soil temperature data are recorded at hourly intervals at depths of 2-, 5-, 10-, and 25-cm. Several other sites have been operationalized over the 8 year period, but have been tampered with, damaged, stolen, or have failed. These partial records are included to provide greater geographic representation of changing conditions where possible. Data indicate decreasing winter soil temperatures in specific land-use and topographic settings. Only one site, located in a dense spruce plantation, experiences soil freezing within the top 5 cm

  13. Active thermal isolation for temperature responsive sensors

    NASA Technical Reports Server (NTRS)

    Martinson, Scott D. (Inventor); Gray, David L. (Inventor); Carraway, Debra L. (Inventor); Reda, Daniel C. (Inventor)

    1994-01-01

    A temperature responsive sensor is located in the airflow over the specified surface of a body and is maintained at a constant temperature. An active thermal isolator is located between this temperature responsive sensor and the specified surface of the body. The temperature of this isolator is controlled to reduce conductive heat flow from the temperature responsive sensor to the body. This temperature control includes: (1) operating the isolator at the same temperature as the constant temperature of the sensor and (2) establishing a fixed boundary temperature which is either less than or equal to or slightly greater than the sensor constant temperature.

  14. 3.5-μm radius race-track microlasers operating at room temperature with 1.3-μm quantum dot active region

    NASA Astrophysics Data System (ADS)

    Kryzhanovskaya, N. V.; Polubavkina, Yu. S.; Scherbak, S. A.; Moiseev, E. I.; Zhurikhina, V. V.; Zubov, F. I.; Lipovskii, A. A.; Kulagina, M. M.; Troshkov, S. I.; Zadiranov, Yu. M.; Maximov, M. V.; Zhukov, A. E.

    2017-01-01

    We present detailed studies of optically pumped InAs/InGaAs quantum dot based racetrack microlasers with 3.5-μm bend radius operating at room temperature. Q factor over 8000 and room temperature threshold power in the mW-range were achieved in the racetrack microlasers with straight section length ranging from 0 to 4 μm. A systematic investigation of the influence of the racetrack straight section length on spatial distribution of optical modes is presented. The microcavity eigenmodes and electromagnetic field distribution calculated by means of three-dimensional numerical simulation demonstrate a good agreement with the experimental results obtained by micro-photoluminescence and scanning near-field optical microscopy. The racetracks demonstrate zigzagging behavior of the modes inside the cavity and the energy switching between the radial maxima in second-order modes. Higher-order modes are found to be suppressed in micro-photoluminescence spectra.

  15. North American regional climate reconstruction from ground surface temperature histories

    NASA Astrophysics Data System (ADS)

    Jaume-Santero, Fernando; Pickler, Carolyne; Beltrami, Hugo; Mareschal, Jean-Claude

    2016-12-01

    Within the framework of the PAGES NAm2k project, 510 North American borehole temperature-depth profiles were analyzed to infer recent climate changes. To facilitate comparisons and to study the same time period, the profiles were truncated at 300 m. Ground surface temperature histories for the last 500 years were obtained for a model describing temperature changes at the surface for several climate-differentiated regions in North America. The evaluation of the model is done by inversion of temperature perturbations using singular value decomposition and its solutions are assessed using a Monte Carlo approach. The results within 95 % confidence interval suggest a warming between 1.0 and 2.5 K during the last two centuries. A regional analysis, composed of mean temperature changes over the last 500 years and geographical maps of ground surface temperatures, show that all regions experienced warming, but this warming is not spatially uniform and is more marked in northern regions.

  16. Rocket measurements of electron temperature in the E region

    NASA Technical Reports Server (NTRS)

    Zimmerman, R. K., Jr.; Smith, L. G.

    1980-01-01

    The rocket borne equipment, experimental method, and data reduction techniques used in the measurement of electron temperature in the E region are fully described. Electron temperature profiles from one daytime equatorial flight and two nighttime midlatitude flights are discussed. The last of these three flights, Nike Apache 14.533, showed elevated E region temperatures which are interpreted as the heating effect of a stable auroral red arc.

  17. CME Productivity of Active Regions.

    NASA Astrophysics Data System (ADS)

    Liu, L.; Wang, Y.; Wang, J.; Shen, C.; Ye, P.; Zhang, Q.; Liu, R.; Wang, S.

    2015-12-01

    Solar active regions (ARs) are the major sources of two kinds of the most violent solar eruptions, namely flares and coronal mass ejections (CMEs). Although they are believed to be two phenomena in the same eruptive process, the productivity of them could be quiet different for various ARs. Why is an AR productive? And why is a flare-rich AR CME-poor? To answer these questions, we compared the recent super flare-rich but CME-poor AR 12192, with other four ARs; two were productive in both flares and CMEs and the other two were inert to produce any M-class or intenser flares or CMEs. By investigating the photospheric parameters based on the SDO/HMI vector magnetogram, we find the three productive ARs have larger magnetic flux, current and free magnetic energy than the inert ARs. Furthermore, the two ARs productive in both flares and CMEs contain higher current helicity, concentrating along both sides of the flaring neutral lines, indicating the presence of a seed magnetic structure( that is highly sheared or twisted) of a CME; they also have higher decay index in the low corona, showing weak constraint. The results suggest that productive ARs are always large and have strong current system and sufficient free energy to power flares, and more importantly whether or not a flare is accompanied by a CME is seemingly related to (1) if there is significant sheared or twisted core field serving as the seed of the CME and (2) if the constraint of the overlying arcades is weak enough. Moreover, some productive ARs may frequently produce more than one CME. How does this happen? We do a statistical investigation of waiting times of quasi-homologous CMEs ( CME ssuccessive originating from the same ARs within short intervals) from super ARs in solar cycle 23 to answer this question. The waiting times of quasi-homologous CMEs have a two-component distribution with a separation at about 18 hours, the first component peaks at 7 hours. The correlation analysis among CME waiting times

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

    NASA Technical Reports Server (NTRS)

    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.

  19. The Twist Limit for Bipolar Active Regions

    NASA Technical Reports Server (NTRS)

    Moore, Ron; Falconer, David; Gary, Allen

    2008-01-01

    We present new evidence that further supports the standard idea that active regions are emerged magnetic-flux-rope omega loops. When the axial magnetic twist of a cylindrical flux rope exceeds a critical amount, the flux rope becomes unstable to kinking, and the excess axial twist is converted into writhe twist by the kinking. This suggests that, if active regions are emerged omega loops, then (1) no active region should have magnetic twist much above the limit set by kinking, (2) active regions having twist near the limit should often arise from kinked omega loops, and (3) since active regions having large delta sunspots are outstandingly twisted, these arise from kinked omega loops and should have twist near the limit for kinking. From each of 36 vector magnetograms of bipolar active regions, we have measured (1) the total flux of the vertical field above 100 G, (2) the area covered by this flux, and (3) the net electric current that arches over the polarity inversion line. These three quantities yield an estimate of the axial magnetic twist in a simple model cylindrical flux rope that corresponds to the top of the active region s hypothetical omega loop prior to emergence. In all 36 cases, the estimated twist is below the critical limit for kinking. The 11 most twisted active regions (1) have estimated twist within a factor of approx.3 of the limit, and (2) include all of our 6 active regions having large delta sunspots. Thus, our observed twist limit for bipolar active regions is in good accord with active regions being emerged omega loops.

  20. Active region coronal loops - Structural and variability

    NASA Technical Reports Server (NTRS)

    Haisch, Bernhard M.; Strong, Keith T.; Harrison, Richard A.; Gary, G. A.

    1988-01-01

    X-ray images of a pair of active region loops are studied which show significant, short time-scale variability in the line fluxes of O VIII, Ne IX, and Mg XI and in the 3.5-11.5 keV soft X-ray bands. Vector magnetograms and high-resolution UV images were used to model the three-dimensional characteristics of the loops. X-ray light curves were generated spanning four consecutive orbits for both loops individually, and light curves of the loop tops and brightest points were also generated. The largest variations involve flux changes of up to several hundred percent on time scales of 10 minutes. No significant H-alpha flare activity is reported, and loop temperatures remain in the four to six million K range. The decay phases of the light curves indicate radiative cooling, inhibition of conduction, and some type of 'continued heating' due to ongoing, underlying activity at the microflare level.

  1. A Multi Wavelength Study of Active Region Development

    NASA Astrophysics Data System (ADS)

    Lara, A.; Gopalswamy, N.; Kundu, M. R.; Perez-Enriquez, R.; Koshiishi, H.; Enome, S.

    1996-05-01

    We report on a study of the evolution of several active regions during 1993 April 17-28 using data obtained at multiple wavelengths that probe various heights of the active region corona. We use simultaneous microwave (1.5 and 17 GHz) and Soft X-ray images obtained by the Very Large Array (VLA), the Nobeyama Radio Heliograph (NRH) and the Soft X-ray Telescope (SXT) on board the Yohkoh spacecraft. We also use photospheric magnetograms from Kitt Peak National Observatory to study the development of Solar Active Regions. We have followed the development of various observed parameters such as brightness temperature and polarization using radio images. The X-ray data were used to track the development of density and temperature of active regions. Using the fact that the quiet active region radiation is thermal and adopting proper emission mechanism at each frequency domain, we construct a consistent picture for the three dimensional structure of the active regions. Particular attention has been paid to the mode coupling observed at 17 GHz while the active regions crossed the solar disk.

  2. Depth of origin of solar active regions

    NASA Technical Reports Server (NTRS)

    Parker, E. N.

    1984-01-01

    Observations show that the individual bipolar magnetic regions on the sun remain confined during their decay phase, with much of the magnetic field pulling back under the surface, in reverse of the earlier emergence. This suggests that the magnetic field is held on a short rein by subsurface forces, for otherwise the region would decay entirely by dispersing across the face of the sun. With the simple assumption that the fields at the surface are controlled from well-defined anchor points at a depth h, it is possible to relate the length l of the bipolar region at the surface to the depth h, with h about equal to l. The observed dimensions l about equal to 100,000 km for normal active regions, and l about equal to 10,000 km for the ephemeral active regions, indicate comparable depths of origin. More detailed observational studies of the active regions may be expected to shed further light on the problem.

  3. THE COLD SHOULDER: EMISSION MEASURE DISTRIBUTIONS OF ACTIVE REGION CORES

    SciTech Connect

    Schmelz, J. T.; Pathak, S.

    2012-09-10

    The coronal heating mechanism for active region core loops is difficult to determine because these loops are often not resolved and cannot be studied individually. Rather, we concentrate on the 'inter-moss' areas between loop footpoints. We use observations from the Hinode EUV Imaging Spectrometer and the X-Ray Telescope to calculate the emission measure distributions of eight inter-moss areas in five different active regions. The combined data sets provide both high- and low-temperature constraints and ensure complete coverage in the temperature range appropriate for active regions. For AR 11113, the emission can be modeled with heating events that occur on timescales less than the cooling time. The loops in the core regions appear to be close to equilibrium and are consistent with steady heating. The other regions studied, however, appear to be dominated by nanoflare heating. Our results are consistent with the idea that active region age is an important parameter in determining whether steady or nanoflare heating is primarily responsible for the core emission, that is, older regions are more likely to be dominated by steady heating, while younger regions show more evidence of nanoflares.

  4. 3D MHD Models of Active Region Loops

    NASA Technical Reports Server (NTRS)

    Ofman, Leon

    2004-01-01

    Present imaging and spectroscopic observations of active region loops allow to determine many physical parameters of the coronal loops, such as the density, temperature, velocity of flows in loops, and the magnetic field. However, due to projection effects many of these parameters remain ambiguous. Three dimensional imaging in EUV by the STEREO spacecraft will help to resolve the projection ambiguities, and the observations could be used to setup 3D MHD models of active region loops to study the dynamics and stability of active regions. Here the results of 3D MHD models of active region loops are presented, and the progress towards more realistic 3D MHD models of active regions. In particular the effects of impulsive events on the excitation of active region loop oscillations, and the generation, propagations and reflection of EIT waves are shown. It is shown how 3D MHD models together with 3D EUV observations can be used as a diagnostic tool for active region loop physical parameters, and to advance the science of the sources of solar coronal activity.

  5. Sensitivity of regional climate to global temperature and forcing

    NASA Astrophysics Data System (ADS)

    Tebaldi, Claudia; O'Neill, Brian; Lamarque, Jean-François

    2015-07-01

    The sensitivity of regional climate to global average radiative forcing and temperature change is important for setting global climate policy targets and designing scenarios. Setting effective policy targets requires an understanding of the consequences exceeding them, even by small amounts, and the effective design of sets of scenarios requires the knowledge of how different emissions, concentrations, or forcing need to be in order to produce substantial differences in climate outcomes. Using an extensive database of climate model simulations, we quantify how differences in global average quantities relate to differences in both the spatial extent and magnitude of climate outcomes at regional (250-1250 km) scales. We show that differences of about 0.3 °C in global average temperature are required to generate statistically significant changes in regional annual average temperature over more than half of the Earth’s land surface. A global difference of 0.8 °C is necessary to produce regional warming over half the land surface that is not only significant but reaches at least 1 °C. As much as 2.5 to 3 °C is required for a statistically significant change in regional annual average precipitation that is equally pervasive. Global average temperature change provides a better metric than radiative forcing for indicating differences in regional climate outcomes due to the path dependency of the effects of radiative forcing. For example, a difference in radiative forcing of 0.5 W m-2 can produce statistically significant differences in regional temperature over an area that ranges between 30% and 85% of the land surface, depending on the forcing pathway.

  6. Suppression of Active-Region CME Production by the Presence of Other Active Regions

    NASA Technical Reports Server (NTRS)

    Falconer, David; Moore, Ron; Barghouty, Abdulnasser; Khazanov, Igor

    2009-01-01

    From the SOHO mission s data base of MDI full-disk magnetograms spanning solar cycle 23, we have obtained a set of 40,000 magnetograms of 1,300 active regions, tracking each active region across the 30 degree central solar disk. Each active region magnetogram is cropped from the full-disk magnetogram by an automated code. The cadence is 96 minutes. From each active-region magnetogram, we have measured two whole-active-region magnetic quantities: (1) the magnetic size of the active region (the active region s total magnetic flux), and (2) a gauge of the active region s free magnetic energy (part of the free energy is released in the production of a flare and/or CME eruption). From NOAA Flare/CME catalogs, we have obtained the event (Flare/CME/SEP event) production history of each active region. Using all these data, we find that for each type of eruptive event, an active region s expected rate of event production increases as a power law of our gauge of active-region free magnetic energy. We have also found that, among active regions having nearly the same free energy, the rate of the CME production is less when there are many other active regions on the disk than when there are few or none, but there is no significant discernible suppression of the rate of flare production. This indicates that the presence of other active regions somehow tends to inhibit an active region s flare-producing magnetic explosions from becoming CMEs, contrary to the expectation from the breakout model for the production of CMEs.

  7. Active Region Emergence and Remote Flares

    NASA Astrophysics Data System (ADS)

    Fu, Yixing; Welsch, Brian T.

    2016-02-01

    We study the effect of new emerging solar active regions on the large-scale magnetic environment of existing regions. We first present a theoretical approach to quantify the "interaction energy" between new and pre-existing regions 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 pre-existing magnetic flux, indicate the existence of "topological" free magnetic energy in the global coronal field that is independent of any "internal" free magnetic energy due to coronal electric currents flowing within the newly emerged and pre-existing flux systems. We then examine the interaction energy in two well-studied cases of flux emergence, but find that the predicted energetic perturbation is relatively small compared to energies released in large solar flares. Next, we present an observational study of the influence of the emergence of new active regions on flare statistics in pre-existing active regions, using NOAA's Solar Region Summary and GOES flare databases. As part of an effort to precisely determine the emergence time of active regions in a large event sample, we find that emergence in about half of these regions exhibits a two-stage behavior, with an initial gradual phase followed by a more rapid phase. Regarding flaring, we find that the emergence of new regions is associated with a significant increase in the occurrence rate of X- and M-class flares in pre-existing regions. This effect tends to be more significant when pre-existing and new emerging active regions are closer. Given the relative weakness of the interaction energy, this effect suggests that perturbations in the large-scale magnetic field, such as topology changes invoked in the "breakout" model of coronal mass ejections, might play a significant role in the occurrence of some flares.

  8. Hinode Captures Images of Solar Active Region

    NASA Video Gallery

    In these images, Hinode's Solar Optical Telescope (SOT) zoomed in on AR 11263 on August 4, 2011, five days before the active region produced the largest flare of this cycle, an X6.9. We show images...

  9. Flare Size Distributions and Active Region Types

    NASA Astrophysics Data System (ADS)

    Bai, Taeil

    2007-05-01

    Size distributions of solar flares measured by various size indicators follow a power law with a negative index of about 1.8. On the basis of general appearance of power-law distributions, Lu and his collegues proposed an avalenche model. According to this model, the power-law index should be independent of active region size, but the cutoff size above which the size distribution steepens rapidly is expected to depend on the active region size. I have analyzed the size distribution of flares, using GOES soft X-ray observations for 2004 and 2005. For flares observed by GOES during these years, their locations are almost completely identified even for C-class flares. This enable us to study the dependence of size distribution on active region type. Comparing the power-law portion of size distributions below the high-end cutoff, I have found that the size distribution index depends on active region type. Flares from prolific active regions exhibit a flatter distribution, while flares from non-prolific active regions exhibit a steeper distribution. I plan to discuss a plausible mechanism for such behavior.

  10. Regional amplification of projected changes in extreme temperatures strongly controlled by soil moisture-temperature feedbacks

    NASA Astrophysics Data System (ADS)

    Vogel, M. M.; Orth, R.; Cheruy, F.; Hagemann, S.; Lorenz, R.; Hurk, B. J. J. M.; Seneviratne, S. I.

    2017-02-01

    Regional hot extremes are projected to increase more strongly than global mean temperature, with substantially larger changes than 2°C even if global warming is limited to this level. We investigate the role of soil moisture-temperature feedbacks for this response based on multimodel experiments for the 21st century with either interactive or fixed (late 20th century mean seasonal cycle) soil moisture. We analyze changes in the hottest days in each year in both sets of experiments, relate them to the global mean temperature increase, and investigate processes leading to these changes. We find that soil moisture-temperature feedbacks significantly contribute to the amplified warming of the hottest days compared to that of global mean temperature. This contribution reaches more than 70% in Central Europe and Central North America. Soil moisture trends are more important for this response than short-term soil moisture variability. These results are relevant for reducing uncertainties in regional temperature projections.

  11. Activation of Phosphorylase Kinase by Physiological Temperature.

    PubMed

    Herrera, Julio E; Thompson, Jackie A; Rimmer, Mary Ashley; Nadeau, Owen W; Carlson, Gerald M

    2015-12-29

    In the six decades since its discovery, phosphorylase kinase (PhK) from rabbit skeletal muscle has usually been studied at 30 °C; in fact, not a single study has examined functions of PhK at a rabbit's body temperature, which is nearly 10 °C greater. Thus, we have examined aspects of the activity, regulation, and structure of PhK at temperatures between 0 and 40 °C. Between 0 and 30 °C, the activity at pH 6.8 of nonphosphorylated PhK predictably increased; however, between 30 and 40 °C, there was a dramatic jump in its activity, resulting in the nonactivated enzyme having a far greater activity at body temperature than was previously realized. This anomalous change in properties between 30 and 40 °C was observed for multiple functions, and both stimulation (by ADP and phosphorylation) and inhibition (by orthophosphate) were considerably less pronounced at 40 °C than at 30 °C. In general, the allosteric control of PhK's activity is definitely more subtle at body temperature. Changes in behavior related to activity at 40 °C and its control can be explained by the near disappearance of hysteresis at physiological temperature. In important ways, the picture of PhK that has emerged from six decades of study at temperatures of ≤30 °C does not coincide with that of the enzyme studied at physiological temperature. The probable underlying mechanism for the dramatic increase in PhK's activity between 30 and 40 °C is an abrupt change in the conformations of the regulatory β and catalytic γ subunits between these two temperatures.

  12. Active Region Moss: Doppler Shifts from Hinode/EIS Observations

    NASA Technical Reports Server (NTRS)

    Tripathi, Durgesh; Mason, Helen E.; Klimchuk, James A.

    2012-01-01

    Studying the Doppler shifts and the temperature dependence of Doppler shifts in moss regions can help us understand the heating processes in the core of the active regions. In this paper we have used an active region observation recorded by the Extreme-ultraviolet Imaging Spectrometer (EIS) onboard Hinode on 12-Dec- 2007 to measure the Doppler shifts in the moss regions. We have distinguished the moss regions from the rest of the active region by defining a low density cut-off as derived by Tripathi et al. (2010). We have carried out a very careful analysis of the EIS wavelength calibration based on the method described in Young, O Dwyer and Mason (2012). For spectral lines having maximum sensitivity between log T = 5.85 and log T = 6.25 K, we find that the velocity distribution peaks at around 0 km/s with an estimated error of 4 km/s. The width of the distribution decreases with temperature. The mean of the distribution shows a blue shift which increases with increasing temperature and the distribution also shows asymmetries towards blue-shift. Comparing these results with observables predicted from different coronal heating models, we find that these results are consistent with both steady and impulsive heating scenarios. Further observational constraints are needed to distinguish between these two heating scenarios.

  13. Active thermal isolation for temperature responsive sensors

    NASA Technical Reports Server (NTRS)

    Martinson, Scott D. (Inventor); Gray, David L. (Inventor); Carraway, Debra L. (Inventor); Reda, Daniel C. (Inventor)

    1994-01-01

    The detection of flow transition between laminar and turbulent flow and of shear stress or skin friction of airfoils is important in basic research for validation of airfoil theory and design. These values are conventionally measured using hot film nickel sensors deposited on a polyimide substrate. The substrate electrically insulates the sensor and underlying airfoil but is prevented from thermally isolating the sensor by thickness constraints necessary to avoid flow contamination. Proposed heating of the model surface is difficult to control, requires significant energy expenditures, and may alter the basic flow state of the airfoil. A temperature responsive sensor is located in the airflow over the specified surface of a body and is maintained at a constant temperature. An active thermal isolator is located between this temperature responsive sensor and the specific surface of the body. The total thickness of the isolator and sensor avoid any contamination of the flow. The temperature of this isolator is controlled to reduce conductive heat flow from the temperature responsive sensor to the body. This temperature control includes (1) operating the isolator at the same temperature as the constant temperature of the sensor; and (2) establishing a fixed boundary temperature which is either less than or equal to, or slightly greater than the sensor constant temperature. The present invention accordingly thermally isolates a temperature responsive sensor in an energy efficient, controllable manner while avoiding any contamination of the flow.

  14. Regional differences in temperature sensation and thermal comfort in humans.

    PubMed

    Nakamura, Mayumi; Yoda, Tamae; Crawshaw, Larry I; Yasuhara, Saki; Saito, Yasuyo; Kasuga, Momoko; Nagashima, Kei; Kanosue, Kazuyuki

    2008-12-01

    Sensations evoked by thermal stimulation (temperature-related sensations) can be divided into two categories, "temperature sensation" and "thermal comfort." Although several studies have investigated regional differences in temperature sensation, less is known about the sensitivity differences in thermal comfort for the various body regions. In the present study, we examined regional differences in temperature-related sensations with special attention to thermal comfort. Healthy male subjects sitting in an environment of mild heat or cold were locally cooled or warmed with water-perfused stimulators. Areas stimulated were the face, chest, abdomen, and thigh. Temperature sensation and thermal comfort of the stimulated areas were reported by the subjects, as was whole body thermal comfort. During mild heat exposure, facial cooling was most comfortable and facial warming was most uncomfortable. On the other hand, during mild cold exposure, neither warming nor cooling of the face had a major effect. The chest and abdomen had characteristics opposite to those of the face. Local warming of the chest and abdomen did produce a strong comfort sensation during whole body cold exposure. The thermal comfort seen in this study suggests that if given the chance, humans would preferentially cool the head in the heat, and they would maintain the warmth of the trunk areas in the cold. The qualitative differences seen in thermal comfort for the various areas cannot be explained solely by the density or properties of the peripheral thermal receptors and thus must reflect processing mechanisms in the central nervous system.

  15. Polar Field Reversals and Active Region Decay

    NASA Astrophysics Data System (ADS)

    Petrie, Gordon; Ettinger, Sophie

    2015-07-01

    We study the relationship between polar field reversals and decayed active region magnetic flux. Photospheric active region flux is dispersed by differential rotation and turbulent diffusion, and is transported poleward by meridional flows and diffusion. We summarize the published evidence from observation and modeling of the influence of meridional flow variations and decaying active region flux's spatial distribution, such as the Joy's law tilt angle. Using NSO Kitt Peak synoptic magnetograms covering cycles 21-24, we investigate in detail the relationship between the transport of decayed active region flux to high latitudes and changes in the polar field strength, including reversals in the magnetic polarity at the poles. By means of stack plots of low- and high-latitude slices of the synoptic magnetograms, the dispersal of flux from low to high latitudes is tracked, and the timing of this dispersal is compared to the polar field changes. In the most abrupt cases of polar field reversal, a few activity complexes (systems of active regions) are identified as the main cause. The poleward transport of large quantities of decayed trailing-polarity flux from these complexes is found to correlate well in time with the abrupt polar field changes. In each case, significant latitudinal displacements were found between the positive and negative flux centroids of the complexes, consistent with Joy's law bipole tilt with trailing-polarity flux located poleward of leading-polarity flux. The activity complexes of the cycle 21 and 22 maxima were larger and longer-lived than those of the cycle 23 and 24 maxima, and the poleward surges were stronger and more unipolar and the polar field changes larger and faster. The cycle 21 and 22 polar reversals were dominated by only a few long-lived complexes whereas the cycle 23 and 24 reversals were the cumulative effects of more numerous, shorter-lived regions. We conclude that sizes and lifetimes of activity complexes are key to

  16. TEMPERATURE STRUCTURE AND METALLICITY IN H II REGIONS

    SciTech Connect

    Rodriguez, Monica; GarcIa-Rojas, Jorge E-mail: jogarcia@iac.e

    2010-01-10

    The metallicities implied by collisionally excited lines (CELs) of heavy elements in H II regions are systematically lower than those implied by recombination lines (RLs) by factors of approx2, introducing uncertainties of the same order in the metallicities inferred for the interstellar medium of any star-forming galaxy. Most explanations of this discrepancy are based on the different sensitivities of CELs and RLs to electron temperature, and invoke either some extra heating mechanism producing temperature fluctuations in the ionized region or the addition of cold gas in metal-rich inclusions or ionized by cosmic rays or X-rays. These explanations will change the temperature structure of the ionized gas from the one predicted by simple photoionization models, and depending on which one is correct, will imply different metallicities for the emitting gas. We select nine H II regions with observed spectra of high quality and show that simple models with metallicities close to the ones implied by oxygen CELs reproduce easily their temperature structure, measured with T{sub e}([N II])/T{sub e}([O III]), and their oxygen CELs emission. We discuss the strong constraints that this agreement places on the possible explanations of the discrepancy and suggest that the simplest explanation, namely errors in the line recombination coefficients by factors approx2, might be the correct one. In such case, CELs will provide the best estimates of metallicity.

  17. North American regional climate reconstruction from underground temperatures.

    NASA Astrophysics Data System (ADS)

    Jaume-Santero, Fernando; Beltrami, Hugo; Mareschal, Jean-Claude

    2016-04-01

    Within the framework of the PAGES NorthAmerica2k project, 514 North American temperature-depth profiles were analyzed to infer recent climate changes. The ground surface temperature (GST) histories for the last 500 years were reconstructed from the subsurface temperature anomalies using a singular value decomposition (SVD) inversion that retains four principal components and takes into account time logging differences. Steady-state surface temperature and thermal gradient were estimated by linear regression for the lower 100 meters of the temperature profile, and climate induced subsurface temperature anomalies were estimated as departures from the steady-state conditions. Additionally, a Monte-Carlo method was used to find the range of solutions within a maximum subsurface anomaly error determined by the minimum distance between the model and the data. A regional analysis was performed for the last 5 centuries yielding mean temperature change every 50 years. The GST history results, presented as the mean and 95% confidence interval, show a warming by 1.0°C to 2.5°C during the post industrial era.

  18. Temperature trends in regions affected by increasing aridity/humidity

    NASA Astrophysics Data System (ADS)

    Jones, Philip D.; Reid, Phillip A.

    A paper in 1991 claimed that regions affected by desertification experience warming trends relative to neighbouring areas. To assess this, an index of aridity/humidity based on the ratio of annual precipitation to annual potential evapotranspiration totals (P/PET) is developed. This index is used to define regions experiencing increases (and those where the increase is statistically significant) in aridity and humidity. We also consider regions always arid (average values of P/PET <0.5) and always humid (P/PET >2.0). Trends of average annual and summer surface air temperature are then calculated for regions in the various aridity/humidity categories and compared to most of the rest of the world's land areas equatorward of 60°. The results indicate that most of the differences in trends between categories are not statistically significant.

  19. Comparing interpolation techniques for annual temperature mapping across Xinjiang region

    NASA Astrophysics Data System (ADS)

    Ren-ping, Zhang; Jing, Guo; Tian-gang, Liang; Qi-sheng, Feng; Aimaiti, Yusupujiang

    2016-11-01

    Interpolating climatic variables such as temperature is challenging due to the highly variable nature of meteorological processes and the difficulty in establishing a representative network of stations. In this paper, based on the monthly temperature data which obtained from the 154 official meteorological stations in the Xinjiang region and surrounding areas, we compared five spatial interpolation techniques: Inverse distance weighting (IDW), Ordinary kriging, Cokriging, thin-plate smoothing splines (ANUSPLIN) and Empirical Bayesian kriging(EBK). Error metrics were used to validate interpolations against independent data. Results indicated that, the ANUSPLIN performed best than the other four interpolation methods.

  20. Operational forecasting of daily temperatures in the Valencia Region. Part I: maximum temperatures in summer.

    NASA Astrophysics Data System (ADS)

    Gómez, I.; Estrela, M.

    2009-09-01

    Extreme temperature events have a great impact on human society. Knowledge of summer maximum temperatures is very useful for both the general public and organisations whose workers have to operate in the open, e.g. railways, roadways, tourism, etc. Moreover, summer maximum daily temperatures are considered a parameter of interest and concern since persistent heat-waves can affect areas as diverse as public health, energy consumption, etc. Thus, an accurate forecasting of these temperatures could help to predict heat-wave conditions and permit the implementation of strategies aimed at minimizing the negative effects that high temperatures have on human health. The aim of this work is to evaluate the skill of the RAMS model in determining daily maximum temperatures during summer over the Valencia Region. For this, we have used the real-time configuration of this model currently running at the CEAM Foundation. To carry out the model verification process, we have analysed not only the global behaviour of the model for the whole Valencia Region, but also its behaviour for the individual stations distributed within this area. The study has been performed for the summer forecast period of 1 June - 30 September, 2007. The results obtained are encouraging and indicate a good agreement between the observed and simulated maximum temperatures. Moreover, the model captures quite well the temperatures in the extreme heat episodes. Acknowledgement. This work was supported by "GRACCIE" (CSD2007-00067, Programa Consolider-Ingenio 2010), by the Spanish Ministerio de Educación y Ciencia, contract number CGL2005-03386/CLI, and by the Regional Government of Valencia Conselleria de Sanitat, contract "Simulación de las olas de calor e invasiones de frío y su regionalización en la Comunidad Valenciana" ("Heat wave and cold invasion simulation and their regionalization at Valencia Region"). The CEAM Foundation is supported by the Generalitat Valenciana and BANCAIXA (Valencia, Spain).

  1. Operational forecasting of daily temperatures in the Valencia Region. Part II: minimum temperatures in winter.

    NASA Astrophysics Data System (ADS)

    Gómez, I.; Estrela, M.

    2009-09-01

    Extreme temperature events have a great impact on human society. Knowledge of minimum temperatures during winter is very useful for both the general public and organisations whose workers have to operate in the open, e.g. railways, roadways, tourism, etc. Moreover, winter minimum temperatures are considered a parameter of interest and concern since persistent cold-waves can affect areas as diverse as public health, energy consumption, etc. Thus, an accurate forecasting of these temperatures could help to predict cold-wave conditions and permit the implementation of strategies aimed at minimizing the negative effects that low temperatures have on human health. The aim of this work is to evaluate the skill of the RAMS model in determining daily minimum temperatures during winter over the Valencia Region. For this, we have used the real-time configuration of this model currently running at the CEAM Foundation. To carry out the model verification process, we have analysed not only the global behaviour of the model for the whole Valencia Region, but also its behaviour for the individual stations distributed within this area. The study has been performed for the winter forecast period from 1 December 2007 - 31 March 2008. The results obtained are encouraging and indicate a good agreement between the observed and simulated minimum temperatures. Moreover, the model captures quite well the temperatures in the extreme cold episodes. Acknowledgement. This work was supported by "GRACCIE" (CSD2007-00067, Programa Consolider-Ingenio 2010), by the Spanish Ministerio de Educación y Ciencia, contract number CGL2005-03386/CLI, and by the Regional Government of Valencia Conselleria de Sanitat, contract "Simulación de las olas de calor e invasiones de frío y su regionalización en la Comunidad Valenciana" ("Heat wave and cold invasion simulation and their regionalization at Valencia Region"). The CEAM Foundation is supported by the Generalitat Valenciana and BANCAIXA (Valencia

  2. Fluxon Modeling of Active Region Evolution

    NASA Astrophysics Data System (ADS)

    Deforest, C. E.; Kankelborg, C. C.; Davey, A. R.; Rachmeler, L.

    2006-12-01

    We present current results and status on fluxon modeling of free energy buildup and release in active regions. Our publicly available code, FLUX, has the unique ability to track magnetic energy buildup with a truly constrained topology in evolving, nonlinear force-free conditions. Recent work includes validation of the model against Low &Lou force-free field solutions, initial evolution studies of idealized active regions, and inclusion of locally parameterized reconnection into the model. FLUX is uniquely able to simulate complete active regions in 3-D on a single workstation; we estimate that a parallelized fluxon model, together with computer vision code to ingest solar data, could run faster than real time on a cluster of \\textasciitilde 30 CPUs and hence provide a true predictive space weather model in the style of predictive simulations of terrestrial weather.

  3. The Magnetic Free Energy in Active Regions

    NASA Technical Reports Server (NTRS)

    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. Three-region characteristic temperature in p-doped quantum dot lasers

    SciTech Connect

    Cao, Yu-Lian E-mail: tyang@semi.ac.cn; Ji, Hai-Ming; Yang, Tao E-mail: tyang@semi.ac.cn; Zhang, Yan-Hua; Ma, Wen-Quan; Wang, Qi-Jie

    2014-01-27

    We have investigated the temperature dependence of threshold in p-doped 1.3 μm InAs/GaAs quantum dot (QD) lasers with ten layers of QDs in the active region. It is found that the dependence of threshold current density on the temperature within the temperature range from 10 to 90 °C can be divided into three regions by its characteristic temperature (T{sub 0}): negative, infinite, and positive T{sub 0} regions. Furthermore, the T{sub 0} region width is dependent on the cavity length: the longer cavity length of the QD lasers correspondingly the wider T{sub 0} region. Additionally, for the broad area laser, the threshold modal gains of the lasers with different cavity lengths can be fitted by an empirical expression as a function of the threshold current density, when at the temperatures of 30, 50, and 70 °C. We find that the transparency current density (J{sub tr}) remains almost unchanged under different temperatures according to the extracted parameters from these fitted results, which indicates that J{sub tr} plays an important role in balancing the T{sub 0} between negative region and positive one.

  5. Dynamics of active regions observed with Hinode XRT

    NASA Astrophysics Data System (ADS)

    Sakao, Taro

    We present dynamics of active regions observed with the X-Ray Telescope (XRT) aboard Hinode. XRT is a grazing-incidence imager with a Walter Type-I-like mirror of 34 cm diameter with a back-illuminated CCD device. The XRT can image the X-ray corona of the Sun with angular resolution consistent with 1 arcsec CCD pixel size. In addition to this unprecedentedly-high angular resolution ever achieved as a solar X-ray telescope, enhanced sensitivity of the CCD towards longer X-ray wavelengths (particularly beyond 50 Angstroms) enables XRT to image, and perform temperature diagnostics on, a wide range of coronal plasmas from those as low as 1 MK to high-temperature plasmas even exceeding 10 MK. This adds a notable advantage to the XRT such that it can observe most, if not all, active phenomena taking place in and around active regions. Since the beginning of observations with XRT on 23 October 2006, the XRT has so far made various interesting observations regarding active regions. These include (1) continuous outflow of plasmas from the edge of a solar active region that is likely to be a source of (slow) solar wind, (2) clear signature of eruptions for activities even down to GOES B-level, (3) detailed structure and evolution of flaring loops, (4) formation of large-scale hot loops around active regions, and so on. Dynamic phenomena in and around active regions observed with Hinode XRT will be presented and their possible implications to the Sun-Earth connection investigation will be discussed.

  6. Active Region Segmentation Based on Stokes Asymmetries

    NASA Astrophysics Data System (ADS)

    Choi, Jieun; Harker-Lundberg, B.

    2011-01-01

    During the Stokes inversion process, we would ideally use a distinct model for each structure in an active region which addresses the differences in the physical conditions of these regions. While the Milne-Eddington model of the atmosphere---a frequently-used ideal model that assumes all local thermodynamic equilibrium (LTE) conditions are satisfied---is a sufficient approximation for the description of the solar photosphere, we almost always observe deviations from this model. It is thus of interest to devise a method to systematically and accurately identify the active regions based on their spectra, such that we could use a more sophisticated model catered to each structure in an active region during the actual Stokes inversion process. We present a classification scheme for different active region structures using Stokes asymmetries and line core depths as discriminators. The data used for this investigation were obtained from the Synoptic Optical Long-term Investigations of the Sun (SOLIS) facility using the Vector Spectromagnetograph (VSM), observed in a 3 A bandpass around Fe I 6302.5 A, from March 27, 2008 to March 29, 2008. This work is carried out through the National Solar Observatory Research Experiences for Undergraduate (REU) site program, which is co-funded by the Department of Defense in partnership with the National Science Foundation REU Program. The National Solar Observatory is operated by the Association of Universities for Research in Astronomy, Inc. (AURA) under cooperative agreement with the National Science Foundation.

  7. ON THE FORMATION OF ACTIVE REGIONS

    SciTech Connect

    Stein, Robert F.; Nordlund, Ake E-mail: aake@nbi.dk

    2012-07-01

    Magnetoconvection can produce an active region without an initial coherent flux tube. A simulation was performed where a uniform, untwisted, horizontal magnetic field of 1 kG strength was advected into the bottom of a computational domain 48 Mm wide by 20 Mm deep. The up and down convective motions produce a hierarchy of magnetic loops with a wide range of scales, with smaller loops riding 'piggy-back' in a serpentine fashion on larger loops. When a large loop approaches the surface, it produces a small active region with a compact leading spot and more diffuse following spots.

  8. Polar Field Reversals and Active Region Decay

    NASA Astrophysics Data System (ADS)

    Petrie, Gordon; Ettinger, Sophie

    2015-04-01

    We study the relationship between polar field reversals and decayed active region magnetic flux. Photospheric active region flux is dispersed by differential rotation and turbulent diffusion, and is transported poleward by meridional flows and diffusion. Using NSO Kitt Peak synoptic magnetograms, we investigate in detail the relationship between the transport of decayed active region flux to high latitudes and changes in the polar field strength, including reversals in the magnetic polarity at the poles. By means of stack plots of low- and high-latitude slices of the synoptic magnetograms, the dispersal of flux from low to high latitudes is tracked, and the timing of this dispersal is compared to the polar field changes. In the most abrupt cases of polar field reversal, a few activity complexes (systems of active regions) are identified as the main cause. The poleward transport of large quantities of decayed lagging-polarity flux from these complexes is found to correlate well in time with the abrupt polar field changes. In each case, significant latitudinal displacements were found between the positive and negative flux centroids of the complexes, consistent with Joy's law bipole tilt with lagging-polarity flux located poleward of leading-polarity flux. This work is carried out through the National Solar Observatory Summer Research Assistantship (SRA) Program. The National Solar Observatory is operated by the Association of Universities for Research in Astronomy, Inc. (AURA) under cooperative agreement with the National Science Foundation.

  9. Static and Dynamic Modeling of a Solar Active Region

    NASA Astrophysics Data System (ADS)

    Warren, Harry P.; Winebarger, Amy R.

    2007-09-01

    Recent hydrostatic simulations of solar active regions have shown that it is possible to reproduce both the total intensity and the general morphology of the high-temperature emission observed at soft X-ray wavelengths using static heating models. These static models, however, cannot account for the lower temperature emission. In addition, there is ample observational evidence that the solar corona is highly variable, indicating a significant role for dynamical processes in coronal heating. Because they are computationally demanding, full hydrodynamic simulations of solar active regions have not been considered previously. In this paper we make first application of an impulsive heating model to the simulation of an entire active region, AR 8156 observed on 1998 February 16. We model this region by coupling potential field extrapolations to full solutions of the time-dependent hydrodynamic loop equations. To make the problem more tractable we begin with a static heating model that reproduces the emission observed in four different Yohkoh Soft X-Ray Telescope (SXT) filters and consider impulsive heating scenarios that yield time-averaged SXT intensities that are consistent with the static case. We find that it is possible to reproduce the total observed soft X-ray emission in all of the SXT filters with a dynamical heating model, indicating that nanoflare heating is consistent with the observational properties of the high-temperature solar corona. At EUV wavelengths the simulated emission shows more coronal loops, but the agreement between the simulation and the observation is still not acceptable.

  10. EUV analysis of an active region. [of solar corona in limb region

    NASA Technical Reports Server (NTRS)

    Raghavan, N.; Withbroe, G. L.

    1975-01-01

    A sequence of extreme-ultraviolet (EUV) spectroheliograms of McMath region No. 10283 were obtained by OSO-6. The lines O VI (1032 A) Mg X (625 A), Si XII (499 A), and Fe XVI (335 A) were used to determine coronal temperatures and densities above the active region. A comparison of theoretical and observed line ratios yielded coronal temperatures of 2.2 to 2.3 million K above the active region and 2.0 to 2.1 million K in the surrounding area. The temperatures derived from ratios involving the O VI intensities are systematically higher than the others. This is attributed to an error in the theoretical O VI intensities. The intensities observed above the limb are compared with intensities predicted by a simple model based on cylindrical geometry. The overall agreement shows that the assumption of an isothermal corona in hydrostatic equilibrium above the active region is a resonable working hypothesis and that the adopted geometrical model for the electron density distribution is adequate.

  11. Active region moss. Basic physical parameters and their temporal variation

    NASA Astrophysics Data System (ADS)

    Tripathi, D.; Mason, H. E.; Del Zanna, G.; Young, P. R.

    2010-07-01

    Context. Active region moss are transition region phenomena, first noted in the images recorded by the Transition Region and Coronal Explorer (TRACE) in λ171. Moss regions are thought to be the footpoints of hot loops (3-5 MK) seen in the core of active regions. These hot loops appear “fuzzy” (unresolved). Therefore, it is difficult to study the physical plasma parameters in individual hot core loops and hence their heating mechanisms. Moss regions provide an excellent opportunity to study the physics of hot loops. In addition, they allow us to study the transition region dynamics in the footpoint regions. Aims: To derive the physical plasma parameters such as temperature, electron density, and filling factors in moss regions and to study their variation over a short (an hour) and a long time period (5 consecutive days). Methods: Primarily, we have analyzed spectroscopic observations recorded by the Extreme-ultraviolet Imaging Spectrometer (EIS) aboard Hinode. In addition we have used supplementary observations taken from TRACE and the X-Ray Telescope (XRT) aboard Hinode. Results: The moss emission is strongest in the Fe XII and Fe XIII lines. Based on analyses using line ratios and emission measure we found that moss regions have a characteristic temperature of log T[K] = 6.2. The temperature structure in moss region remains almost identical from one region to another and it does not change with time. The electron densities measured at different locations in the moss regions using Fe XII ratios are about 1-3 × 1010 cm-3 and about 2-4 × 109 cm-3 using Fe XIII and Fe XIV. The densities in the moss regions are similar in different places and show very little variation over short and long time scales. The derived electron density substantially increased (by a factor of about 3-4 or even more in some cases) when a background subtraction was performed. The filling factor of the moss plasma can vary between 0.1-1 and the path length along which the emission

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  13. High temperature garnet growth in New England: regional temperature-time trends revealed

    NASA Astrophysics Data System (ADS)

    Sullivan, N.; Ostwald, C.; Chu, X.; Baxter, E. F.; Ague, J. J.; Eckert, J. O.

    2013-12-01

    A series of localized ultrahigh-temperature (UHT)/high-temperature (HT) granulite facies regions have been identified within the regional amphibolite facies metamorphic zone of the Central Maine Terrane stretching from north-central New Hampshire, through central Massachusetts, and into northeastern Connecticut. Here, we aim to constrain the age and peak temperature of metamorphism at three localities within this region: Bristol, NH, Phillipston, MA and Willington, CT. Garnet-forming reactions are linked directly to peak metamorphic temperatures through thermodynamic modeling and/or Zr-in-rutile thermometry. Precise garnet geochronology allows us to identify the timing of these peak temperatures, as well as the duration of garnet growth. Geochronologic and thermodynamic work was done on 12 samples collected throughout a ~5 km2 metamorphic 'hotspot' previously identified in Bristol, NH (Chamberlain and Rumble, 1988; Journal of Petrology). The highest temperature assemblage within this hotspot is characterized by the presence of garnet + sillimanite + K-feldspar + cordierite and reached temperatures >820οC. The lowest temperature periphery of the hotspot is characterized by sillimanite + muscovite + K-feldspar + minor garnet and reached a maximum temperature of 650οC. Bulk garnet ages from samples within the hotspot range significantly from at least 400.0 × 2.5 Ma to 352.7 × 1.8 Ma with the youngest ages associated with the lower temperature samples. This collection of ages indicates a prolonged period (~50 Ma) of >650οC temperatures interspersed by period(s) of garnet growth. Zoned garnet geochronology will help reveal whether garnet growth and related heating was continuous or episodic. Further south, in Phillipston, MA, zoned garnet geochronology performed on a 2.5 cm diameter garnet porphyroblast indicates garnet growth spanning 389 - 363 Ma, reaching peak temperatures at the end of that time span of 920-940οC, followed by a younger event recorded in

  14. EVIDENCE OF IMPULSIVE HEATING IN ACTIVE REGION CORE LOOPS

    SciTech Connect

    Tripathi, Durgesh; Mason, Helen E.; Klimchuk, James A.

    2010-11-01

    Using a full spectral scan of an active region from the Extreme-Ultraviolet Imaging Spectrometer (EIS) we have obtained emission measure EM(T) distributions in two different moss regions within the same active region. We have compared these with theoretical transition region EMs derived for three limiting cases, namely, static equilibrium, strong condensation, and strong evaporation from Klimchuk et al. The EM distributions in both the moss regions are strikingly similar and show a monotonically increasing trend from log T[K] = 5.15-6.3. Using photospheric abundances, we obtain a consistent EM distribution for all ions. Comparing the observed and theoretical EM distributions, we find that the observed EM distribution is best explained by the strong condensation case (EM{sub con}), suggesting that a downward enthalpy flux plays an important and possibly dominant role in powering the transition region moss emission. The downflows could be due to unresolved coronal plasma that is cooling and draining after having been impulsively heated. This supports the idea that the hot loops (with temperatures of 3-5 MK) seen in the core of active regions are heated by nanoflares.

  15. Helium Line Formation and Abundance in a Solar Active Region

    NASA Astrophysics Data System (ADS)

    Mauas, P. J. D.; Andretta, V.; Falchi, A.; Falciani, R.; Teriaca, L.; Cauzzi, G.

    2005-01-01

    An observing campaign (SOHO JOP 139), coordinated between ground-based and Solar and Heliospheric Observatory (SOHO) instruments, has been planned to obtain simultaneous spectroheliograms of the same active region in several spectral lines. The chromospheric lines Ca II K, Hα, and Na I D, as well as He I 10830, 5876, 584, and He II 304 Å lines have been observed. The EUV radiation in the range λ<500 Å and in the range 260<λ<340 Å has also been measured at the same time. These simultaneous observations allow us to build semiempirical models of the chromosphere and low transition region of an active region, taking into account the estimated total number of photoionizing photons impinging on the target active region and their spectral distribution. We obtained a model that matches very well all the observed line profiles, using a standard value for the He abundance ([He]=0.1) and a modified distribution of microturbulence. For this model we study the influence of the coronal radiation on the computed helium lines. We find that, even in an active region, the incident coronal radiation has a limited effect on the UV He lines, while it is of fundamental importance for the D3 and 10830 Å lines. Finally, we build two more models, assuming values of He abundance [He]=0.07 and 1.5, only in the region where temperatures are >1×104 K. This region, between the chromosphere and transition region, has been indicated as a good candidate for processes that might be responsible for strong variations of [He]. The set of our observables can still be well reproduced in both cases, changing the atmospheric structure mainly in the low transition region. This implies that, to choose between different values of [He], it is necessary to constrain the transition region with different observables, independent of the He lines.

  16. Temperature, activity, and lizard life histories.

    PubMed

    Adolph, S C; Porter, W P

    1993-08-01

    Lizard life-history characteristics vary widely among species and populations. Most authors seek adaptive or phylogenetic explanations for life-history patterns, which are usually presumed to reflect genetic differences. However, lizard life histories are often phenotypically plastic, varying in response to temperature, food availability, and other environmental factors. Despite the importance of temperature to lizard ecology and physiology, its effects on life histories have received relatively little attention. We present a theoretical model predicting the proximate consequences of the thermal environment for lizard life histories. Temperature, by affecting activity times, can cause variation in annual survival rate and fecundity, leading to a negative correlation between survival rate and fecundity among populations in different thermal environments. Thus, physiological and evolutionary models predict the same qualitative pattern of life-history variation in lizards. We tested our model with published life-history data from field studies of the lizard Sceloporus undulatus, using climate and geographical data to reconstruct estimated annual activity seasons. Among populations, annual activity times were negatively correlated with annual survival rate and positively correlated with annual fecundity. Proximate effects of temperature may confound comparative analyses of lizard life-history variation and should be included in future evolutionary models.

  17. Temperature, activity, and lizard life histories

    SciTech Connect

    Adolph, S.C.; Porter, W.P. )

    1993-08-01

    Lizard life-history characteristics vary widely among species and populations. Most authors seek adaptive or phylogenetic explanations for life-history patterns, which are usually presumed to reflect genetic differences. However, lizard life histories are often phenotypically plastic, varying in response to temperature, food availability, and other environmental factors. Despite the importance of temperature to lizard ecology and physiology, its effects on life histories have received relatively little attention. The authors present a theoretical model predicting the proximate consequences of the thermal environment for lizard life histories. Temperature, by affecting activity times, can cause variation in annual survival rate and fecundity, leading to a negative correlation between survival rate and fecundity among populations in different thermal environments. Thus, physiological and evolutionary models predict the same qualitative pattern of life-history variation in lizards. They tested their model with published life-history data from field studies of the lizard Sceloporus undulatus, using climate and geographical data to reconstruct estimated annual activity seasons. Among populations, annual activity times were negatively correlated with annual survival rate and positively correlated with annual fecundity. Proximate effects of temperature may confound comparative analyses of lizard life-history variation and should be included in future evolutionary models. 125 refs., 6 figs., 1 tab.

  18. Land surface temperature shaped by urban fractions in megacity region

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoxuan; Hu, Yonghong; Jia, Gensuo; Hou, Meiting; Fan, Yanguo; Sun, Zhongchang; Zhu, Yuxiang

    2017-02-01

    Large areas of cropland and natural vegetation have been replaced by impervious surfaces during the recent rapid urbanization in China, which has resulted in intensified urban heat island effects and modified local or regional warming trends. However, it is unclear how urban expansion contributes to local temperature change. In this study, we investigated the relationship between land surface temperature (LST) change and the increase of urban land signals. The megacity of Tianjin was chosen for the case study because it is representative of the urbanization process in northern China. A combined analysis of LST and urban land information was conducted based on an urban-rural transect derived from Landsat 8 Thermal Infrared Sensor (TIRS), Terra Moderate Resolution Imaging Spectrometer (MODIS), and QuickBird images. The results indicated that the density of urban land signals has intensified within a 1-km2 grid in the urban center with an impervious land fraction >60 %. However, the construction on urban land is quite different with low-/mid-rise buildings outnumbering high-rise buildings in the urban-rural transect. Based on a statistical moving window analysis, positive correlation ( R 2 > 0.9) is found between LST and urban land signals. Surface temperature change (ΔLST) increases by 0.062 °C, which was probably caused by the 1 % increase of urbanized land (ΔIF) in this case region.

  19. Silicon on insulator with active buried regions

    DOEpatents

    McCarthy, Anthony M.

    1996-01-01

    A method for forming patterned buried components, such as collectors, sources and drains, in silicon-on-insulator (SOI) devices. The method is carried out by epitaxially growing a suitable sequence of single or multiple etch stop layers ending with a thin silicon layer on a silicon substrate, masking the silicon such that the desired pattern is exposed, introducing dopant and activating in the thin silicon layer to form doped regions. Then, bonding the silicon layer to an insulator substrate, and removing the silicon substrate. The method additionally involves forming electrical contact regions in the thin silicon layer for the buried collectors.

  20. Silicon on insulator with active buried regions

    DOEpatents

    McCarthy, A.M.

    1998-06-02

    A method is disclosed for forming patterned buried components, such as collectors, sources and drains, in silicon-on-insulator (SOI) devices. The method is carried out by epitaxially growing a suitable sequence of single or multiple etch stop layers ending with a thin silicon layer on a silicon substrate, masking the silicon such that the desired pattern is exposed, introducing dopant and activating in the thin silicon layer to form doped regions. Then, bonding the silicon layer to an insulator substrate, and removing the silicon substrate. The method additionally involves forming electrical contact regions in the thin silicon layer for the buried collectors. 10 figs.

  1. Silicon on insulator with active buried regions

    DOEpatents

    McCarthy, A.M.

    1996-01-30

    A method is disclosed for forming patterned buried components, such as collectors, sources and drains, in silicon-on-insulator (SOI) devices. The method is carried out by epitaxially growing a suitable sequence of single or multiple etch stop layers ending with a thin silicon layer on a silicon substrate, masking the silicon such that the desired pattern is exposed, introducing dopant and activating in the thin silicon layer to form doped regions. Then, bonding the silicon layer to an insulator substrate, and removing the silicon substrate. The method additionally involves forming electrical contact regions in the thin silicon layer for the buried collectors. 10 figs.

  2. Silicon on insulator with active buried regions

    DOEpatents

    McCarthy, Anthony M.

    1998-06-02

    A method for forming patterned buried components, such as collectors, sources and drains, in silicon-on-insulator (SOI) devices. The method is carried out by epitaxially growing a suitable sequence of single or multiple etch stop layers ending with a thin silicon layer on a silicon substrate, masking the silicon such that the desired pattern is exposed, introducing dopant and activating in the thin silicon layer to form doped regions. Then, bonding the silicon layer to an insulator substrate, and removing the silicon substrate. The method additionally involves forming electrical contact regions in the thin silicon layer for the buried collectors.

  3. Magnetic helicity in emerging solar active regions

    SciTech Connect

    Liu, Y.; Hoeksema, J. T.; Bobra, M.; Hayashi, K.; Sun, X.; Schuck, P. W.

    2014-04-10

    Using vector magnetic field data from the Helioseismic and Magnetic Imager instrument aboard the Solar Dynamics Observatory, we study magnetic helicity injection into the corona in emerging active regions (ARs) and examine the hemispheric helicity rule. In every region studied, photospheric shearing motion contributes most of the helicity accumulated in the corona. In a sample of 28 emerging ARs, 17 follow the hemisphere rule (61% ± 18% at a 95% confidence interval). Magnetic helicity and twist in 25 ARs (89% ± 11%) have the same sign. The maximum magnetic twist, which depends on the size of an AR, is inferred in a sample of 23 emerging ARs with a bipolar magnetic field configuration.

  4. Supergranule Diffusion and Active Region Decay

    NASA Technical Reports Server (NTRS)

    Hathaway, David H.; Choudhary, Debi Prasad

    2004-01-01

    Models of the Sun's magnetic dynamo include turbulent diffusion to parameterize the effects of convective motions on the evolution of the Sun's magnetic field. Supergranules are known to dominate the evolution of the surface magnetic field structure as evidenced by the structure of both the active and quiet magnetic network. However, estimates for the dif hivity attributed to su perymules differ by an order of magnitude from about 100 km sup2/s to more than 1000 km sup2/s. We examine this question of the e i v i t y using three merent approaches. 1) We study the decay of more than 30,000 active regions by determining the rate of change in the sunspot area of each active region from day-to-day. 2) We study the decay of a single isolated active region near the time of solar minimum by examining the magnetic field evolution over five solar rotations fiom SOHOMDI magnetograms obtained at 96-minute intervals. 3) We study the characteristics of supergranules that influence the estimates of their diffusive properties - flow speeds and lifetimes as functions of size - fiom SOHO/MDI Dopplergrams.

  5. Analysis Of The High Temperature Region In Be Stars

    NASA Astrophysics Data System (ADS)

    Torres, A. F.; Ringuelet, A. E.

    2006-08-01

    The High Temperature Region (HTR) that surrounds the photospheres of Be stars is studied in order to derive observational constraints for modelling Be stars, in particular for the region where superionization takes place. 50 Be stars, representative of a considerable range of temperature, were chosen. From archival, high-dispersion IUE spectra, different lines that originate in the HTR region were considered, namely the resonance lines of Si IV, C IV and Al III, and He II λ 1640. Equivalent widths (corrected for photospheric contribution), optical depths, atom columns and expansion velocities were measured. From this observational data several correlations between different observables were obtained. These correlations permit us to discuss the geometry, density distribution and heat input of the lines formation regions (LFRs). The major results can be summarised as follows: 1) The circumstellar material contributes to the resonance lines of Si IV, C IV, Al III and to the He II λ 1640 at all inclination angles. 2) In Si IV, C IV and Al III the equivalent widths have a tendency to increase in objects with high rotational velocities. 3) Si IV and C IV equivalent widths are also correlated to the kinetic energy of the expansion velocity. This means that dissipation of mechanical energy is one of the heating mechanisms. 4)On the basis of the expansion velocities and the line profiles, we establish a sequence for the LFRs: The LFR of He II is at the base of the wind and the closest to the central star. The LFRs of Si IV and C IV are inmersed in the stellar wind. The LFR of Al III is an interface between the HTR and the cool envelope. The analysis followed in this work is completely model-independent. Consequently, these results could be useful to decide which are the facts that are to be considered when modelling Be stars.

  6. Effective temperature of ionizing stars of extragalactic H II regions

    NASA Astrophysics Data System (ADS)

    Dors, O. L.; Hägele, G. F.; Cardaci, M. V.; Krabbe, A. C.

    2017-04-01

    The effective temperature (Teff) of the radiation field of the ionizing star(s) of a large sample of extragalactic H II regions was estimated using the R = log([O II] (λλ3726 + 29)/[O III] λ5007) index. We used a grid of photoionization models to calibrate the Teff-R relation finding that it has a strong dependence with the ionizing parameter, while it shows a weak direct dependence with the metallicity (variations in Z imply variations in U) of both the stellar atmosphere of the ionizing star and the gas phase of the H II region. Since the R index varies slightly with the Teff for values larger than 40 kK, the R index can be used to derive the Teff in the 30-40 kK range. A large fraction of the ionization parameter variation is due to differences in the temperature of the ionizing stars and then the use of the (relatively) low Teff dependent S2 = [S II] (λλ6717 + 31)/Hα emission-line ratio to derive the ionization parameter is preferable over others in the literature. We propose linear metallicity dependent relationships between S2 and U. Teff and metallicity estimations for a sample of 865 H II regions, whose emission-line intensities were compiled from the literature, do not show any Teff-Z correlation. On the other hand, it seems to be hints of the presence of an anticorrelation between Teff-U. We found that the majority of the studied H II regions (∼87 per cent) present Teff values in the range between 37 and 40 kK, with an average value of 38.5(±1) kK. We also studied the variation of Teff as a function of the galactocentric distance for 14 spiral galaxies. Our results are in agreement with the idea of the existence of positive Teff gradients along the disc of spiral galaxies.

  7. Patterns of helicity in solar active regions

    NASA Technical Reports Server (NTRS)

    Pevtsov, Alexei A.; Canfield, Richard C.; Metcalf, Thomas R.

    1994-01-01

    Using 46 vector magnetograms from the Stokes Polarimeter of Mees Solar Observatory (MSO), we studied patterns of local helicity in three diverse solar active regions. From these magnetograms we computed maps of the local helicity parameter alpha = J(sub z)/B(sub z). Although such maps are noisy, we found patterns at the level approximately 2 to 3 sigma(sub J(sub z)), which repeat in successive magnetograms for up to several days. Typically, the alpha maps of any given active region contain identifiable patches with both positive and negative values of alpha. Even within a single sunspot complex, several such alpha patches can often be seen. We followed 68 alpha patches that could be identified on at least two successive alpha maps. We found that the persistence fraction of such patches decrease exponentially, with a characteristic time approximately 27 hr.

  8. Groundwater temperature transients on the Armutlu peninsula, eastern Marmara region

    NASA Astrophysics Data System (ADS)

    Woith, Heiko; Caka, Deniz; Seyis, Cemil; Italiano, Francesco; Celik, Cengiz; Wang, Rongjiang; Baris, Serif

    2016-04-01

    Since many years MAM and GFZ in co-operation with Kocaeli University (KU) operate fluid monitoring stations around the Sea of Marmara. In the frame of MARsite (MARsite has received funding from the European Union's Seventh Programme for research, technological development and demonstration under grant agreement No 308417) these networks were jointly evaluated for the first time. The on-land fluid monitoring networks continuously monitor the following parameters: soil radon (21 sites), temperature and conductivity of thermal springs (9 sites) operated by MAM covering the whole Marmara region; fluid pressure and water level/temperature (8 sites) within ARNET operated by GFZ/KU. ARNET is a combined seismological/hydrogeological monitoring network covering the Armutlu peninsula located SE of Istanbul. Additional to the geothermal wells and springs - our main target to detect transients of potentially seismo-tectonic origin - three shallow groundwater wells (tenth of meters deep) are being operated to identify and quantify seasonal variations, and meteorological influences like rainfall and snowmelt. But it turned out that these shallow aquifer systems showed very stable conditions with very small annual temperature amplitudes (0.2 - 0.3°C). One of these shallow monitoring wells is located just south of Lake Iznik (in the village of Sölöz) very close to the southern branch of the North Anatolian Fault Zone. Water level showed a steady decreasing trend since June 2012. This trend resulted in a data gap starting in January 2014, when the water level dropped below the sensor position. After adjusting the sensor position, positive spikes in the borehole temperature were recorded in June and August 2014, and again in 2015. The spikes are characterised by a sharp temperature increase followed by a decay lasting several days until the pre-event temperature was reached again. Since the spikes occurred on two independent logger systems, and since they lasted several days, a

  9. Temperature (de)activated patchy colloidal particles.

    PubMed

    de Las Heras, Daniel; da Gama, Margarida M Telo

    2016-06-22

    We present a new model of patchy particles in which the interaction sites can be activated or deactivated by varying the temperature of the system. We study the thermodynamics of the system by means of Wertheim's first order perturbation theory, and use Flory-Stockmayer theory of polymerization to analyse the percolation threshold. We find a very rich phase behaviour including lower critical points and reentrant percolation.

  10. Physical Properties of Cooling Plasma in Quiescent Active Region Loops

    NASA Astrophysics Data System (ADS)

    Landi, E.; Miralles, M. P.; Curdt, W.; Hara, H.

    2009-04-01

    In the present work, we use SOHO/SUMER, SOHO/UVCS, SOHO/EIT, SOHO/LASCO, STEREO/EUVI, and Hinode/EIS coordinated observations of an active region (AR 10989) at the west limb taken on 2008 April 8 to study the cooling of coronal loops. The cooling plasma is identified using the intensities of SUMER spectral lines emitted at temperatures in the 4.15 <= log T <= 5.45 range. EIS and SUMER spectral observations are used to measure the physical properties of the loops. We found that before cooling took place these loops were filled with coronal hole-like plasma, with temperatures in the 5.6 <= log T <= 5.9 range. SUMER spectra also allowed us to determine the plasma temperature, density, emission measure, element abundances, and dynamic status during the cooling process. The ability of EUVI to observe the emitting region from a different direction allowed us to measure the volume of the emitting region and estimate its emission measure. Comparison with values measured from line intensities provided us with an estimate of the filling factor. UVCS observations of the coronal emission above the active region showed no streamer structure associated with AR 10989 at position angles between 242°and 253fdg EIT, LASCO, and EUVI-A narrowband images and UVCS spectral observations were used to discriminate between different scenarios and monitor the behavior of the active region in time. The present study provides the first detailed measurements of the physical properties of cooling loops, a very important benchmark for theoretical models of loop cooling and condensation.

  11. Rainfall and temperature estimation for a data sparse region

    NASA Astrophysics Data System (ADS)

    Yu, D.; Wilby, R. L.

    2013-12-01

    Development agencies often face difficult decisions about where and how to prioritise climate risk reduction measures. These tasks are especially challenging in data sparse regions with few meteorological stations, complex topography and extreme weather events. At the same time, these regions are also often highly vulnerable to climate risks. In this study, we blend surface meteorological observations, remotely sensed (TRMM and NDVI) data, physiographic indices, and regression techniques to produce gridded maps of annual mean precipitation and temperature, as well as parameters for site-specific, daily weather generation in Yemen. Maps of annual means were cross-validated and tested against independent observations. These replicated known features such as peak rainfall totals in the Highlands and western escarpment, as well as maximum temperatures along the coastal plains and interior. The weather generator reproduced daily and annual diagnostics when run with parameters from observed meteorological series for a test site at Taiz. However, when run with interpolated parameters, the frequency of wet-days, mean wet-day amount, annual totals and variability were underestimated. Stratification of sites for model calibration improved representation of growing season rainfall totals. We conclude that local terrain and remotely sensed variables can be used to infer annual mean temperature and precipitation across the most populous, south-west area of Yemen. Important features of the daily and seasonal weather can also be simulated at the site scale, but more rigorous validation is ultimately constrained by lack of data. Future work should focus on a wider range of model inputs to better discriminate controls exerted by different landscape units.

  12. Stagnation region gas film cooling: Effects of dimensionless coolant temperature

    NASA Technical Reports Server (NTRS)

    Bonnice, M. A.; Lecuyer, M. R.

    1983-01-01

    An experimental investigation was conducted to mode the film cooling performance for a turbine vane leading edge using the stagnation region of a cylinder in cross flow. Experiments were conducted with a single row of spanwise angled (25 deg) coolant holes for a range of the coolant blowing ratio and dimensionless coolant temperature with free stream-to-wall temperature ratio approximately 1.7 and Re sub D = 90000. the cylindrical test surface was instrumented with miniature heat flux gages and wall thermocouples to determine the percentage reduction in the Stanton number as a function of the distance downstream from injection (x/d sub 0) and the location between adjacent holes (z/S). Data from local heat flux measurements are presented for injection from a single row located at 5 deg, 22.9 deg, 40.8 deg, from stagnation using a hole spacing ratio of S/d = 5. The film coolant was injected with T sub c T sub w with a dimensionless coolant temperature in the range 1.18 or equal to theta sub c or equal to 1.56. The data for local Stanton Number Reduction (SNR) showed a significant increase in SNR as theta sub c was increased above 1.0.

  13. OBSERVING CORONAL NANOFLARES IN ACTIVE REGION MOSS

    SciTech Connect

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

    2013-06-10

    The High-resolution Coronal Imager (Hi-C) has provided Fe XII 193A images of the upper transition region moss at an unprecedented spatial ({approx}0.''3-0.''4) and temporal (5.5 s) resolution. The Hi-C observations show in some moss regions variability on timescales down to {approx}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 A 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 10{sup 23} 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).

  14. Solar irradiance variations due to active regions

    SciTech Connect

    Oster, L.; Schatten, K.H.; Sofia, S.

    1982-05-15

    We have been able to reproduce the variations of the solar irradiance observed by ACRIM to an accuracy of better than +- 0.4 W m/sup -2/, assuming that during the 6 month observation period in 1980 the solar luminosity was constant. The improvement over previous attempts is primarily due to the inclusion of faculae. The reproduction scheme uses simple geometrical data on spot and facula areas, and conventional parameters for the respective fluxes and angular dependencies. The quality of reproduction is not very sensitive to most of the details of these parameters; nevertheless, there conventional parameters cannot be very different from their actual values in the solar atmosphere. It is interesting that the time average of the integrated excess emission (over directions) of the faculae cancels out the integrated deficit produced by the spots, within an accuracy of about 10%. If this behavior were maintained over longer periods of time, say, on the order of an activity cycle, active regions could be viewed as a kind of lighthouse where the energy deficit near the normal direction, associated with the spots, is primarily reemitted close to the tangential directions by the faculae. The currently available data suggest that energy ''storage'' associated with the redirection of flux near active regions on the Sun is comparable to the lifetime of the faculae.

  15. Regional synchrony of temperature variation and internal wave forcing along the Florida Keys reef tract

    NASA Astrophysics Data System (ADS)

    Leichter, James J.; Stokes, M. Dale; Vilchis, L. Ignacio; Fiechter, Jerome

    2014-01-01

    Analysis of 10 year temperature records collected along the Florida Keys reef tract (FLKRT) reveals strong, regional-scale synchrony in high-frequency temperature variation suggestive of internal wave forcing at predominately semidiurnal frequencies. In each year and at all sites, the amplitude of semidiurnal temperature variation was greatest from March to September, and markedly lower from October to February. Comparisons of the semidiurnal component of the temperature variation among sites suggest complex patterns in the arrival of internal waves, with highest cross correlation among closely spaced sites and synchrony in periods of enhanced internal wave activity across the length of the FLKRT, particularly in summer. The periods of enhanced semidiurnal temperature variation at the 20 and 30 m isobaths on the reef slopes appear to be associated with the dynamics of the Florida Current and the onshore movement of warm fronts preceding the passage of Florida Current frontal eddies. Regional-scale satellite altimetry observations suggest temporal linkages to sea surface height anomalies in the Loop Current (upstream of the Florida Current) and setup of the Tortugas Gyre. The synchronized forcing of cool water onto the reef slope sites across the FLKRT is likely to affect physiological responses to temperature variation in corals and other ectothermic organisms, as well as larval transport and nutrient dynamics with the potential for regionally coherent pulses of larvae and nutrients arriving on reef slopes across the FLKRT.

  16. Temperature Regulator for Actively Cooled Structures

    NASA Technical Reports Server (NTRS)

    Blosser, Max (Inventor); Kelly, H. Neale (Inventor)

    1995-01-01

    In active cooling of a structure it is beneficial to use a plurality of passages for conducting coolant to various portions of the structure. Since most structures do not undergo isotropic thermal loads it is desirable to allow for variation in coolant flow to each area of the structure. The present invention allows for variable flow by a variation of the area of a portion of each of the coolant passages. Shape memory alloys and bi-material springs are used to produce passages that change flow area as a function of temperature.

  17. Rainfall and temperature estimation for a data sparse region

    NASA Astrophysics Data System (ADS)

    Wilby, R. L.; Yu, D.

    2013-10-01

    Humanitarian and development agencies face difficult decisions about where and how to prioritise climate risk reduction measures. These tasks are especially challenging in regions with few meteorological stations, complex topography and extreme weather events. In this study, we blend surface meteorological observations, remotely sensed (TRMM and NDVI) data, physiographic indices, and regression techniques to produce gridded maps of annual mean precipitation and temperature, as well as parameters for site-specific, daily weather generation in Yemen. Maps of annual means were cross-validated and tested against independent observations. These replicated known features such as peak rainfall totals in the highlands and western escarpment, as well as maximum temperatures along the coastal plains and interior. The weather generator reproduced daily and annual diagnostics when run with parameters from observed meteorological series for a test site at Taiz. However, when run with interpolated parameters, the frequency of wet days, mean wet-day amount, annual totals and variability were underestimated. Stratification of sites for model calibration improved representation of the growing season's rainfall totals. Future work should focus on a wider range of model inputs to better discriminate controls exerted by different landscape units.

  18. Rainfall and temperature estimation for a data sparse region

    NASA Astrophysics Data System (ADS)

    Wilby, R. L.; Yu, D.

    2013-06-01

    Agencies face difficult decisions about where and how to prioritise climate risk reduction measures. These tasks are especially challenging in regions with few meteorological stations, complex topography and extreme weather events. In this study, we blend surface meteorological observations, remotely sensed (TRMM and NDVI) data, physiographic indices, and regression techniques to produce gridded maps of annual mean precipitation and temperature, as well as parameters for site-specific, daily weather generation in Yemen. Maps of annual means were cross-validated and tested against independent observations. These replicated known features such as peak rainfall totals in the Highlands and western escarpment, as well as maximum temperatures along the coastal plains and interior. The weather generator reproduced daily and annual diagnostics when run with parameters from observed meteorological series for a test site at Taiz. However, when run with interpolated parameters, the frequency of wet-days, mean wet-day amount, annual totals and variability were underestimated. Stratification of sites for model calibration improved representation of growing season rainfall totals. Future work should focus on a wider range of model inputs to better discriminate controls exerted by different landscape units.

  19. Pederson Current Dissipation In Emerging Active Regions

    NASA Astrophysics Data System (ADS)

    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).

  20. HEROES Observations of a Quiescent Active Region

    NASA Astrophysics Data System (ADS)

    Shih, A. Y.; Christe, S.; Gaskin, J.; Wilson-Hodge, C.

    2014-12-01

    Hard X-ray (HXR) observations of solar flares reveal the signatures of energetic electrons, and HXR images with high dynamic range and high sensitivity can distinguish between where electrons are accelerated and where they stop. Even in the non-flaring corona, high-sensitivity HXR measurements may be able to detect the presence of electron acceleration. The High Energy Replicated Optics to Explore the Sun (HEROES) balloon mission added the capability of solar observations to an existing astrophysics balloon payload, HERO, which used grazing-incidence optics for direct HXR imaging. HEROES measures HXR emission from ~20 to ~75 keV with an angular resolution of 33" HPD. HEROES launched on 2013 September 21 from Fort Sumner, New Mexico, and had a successful one-day flight. We present the detailed analysis of the 7-hour observation of AR 11850, which sets new upper limits on the HXR emission from a quiescent active region, with corresponding constraints on the numbers of tens of keV energetic electrons present. Using the imaging capability of HEROES, HXR upper limits are also obtained for the quiet Sun surrounding the active region. We also discuss what can be achieved with new and improved HXR instrumentation on balloons.

  1. Active Region Transient Brightenings : EIT Versus SXT

    NASA Astrophysics Data System (ADS)

    Berghmans, D.; McKenzie, D.; Clette, F.

    1999-10-01

    On May 13, 1998, the Extreme-Ultraviolet Imaging Telescope (EIT, on board SOHO) has produced a unique image sequence operating in 'shutterless mode' (SOHO JOP 80). In JOP 80, EIT is the leading instrument, followed by several space born instruments (SXT, TRACE, MDI, CDS, SUMER), as well as two observatories on the ground (in La Palma and Sac Peak). The target of the campaign was a relatively small but rapidly evolving active region (AR 8218). For the EIT contribution, a 15 s cadence was achieved in the Fe XII bandpass at 195 deg by leaving EIT's shutter open for 1 hour and operating the CCD in frame transfer mode. We have started the analysis of the huge data set, by making an inventory of the transients observed in the EIT image sequence. These transients range from a B3.5 flare producing a large plasma flow along pre-existing loops, to smaller EUV brightenings of active region loops. In addition, a new class of weaker footpoint brightenings was discovered that produce wave-like disturbances propagating along quasi-open field lines (see the presentation by Eva Robbrecht at this workshop). In this paper we take the opportunity provided by JOP 80, to investigate the correspondence of the transient brightenings observed by EIT in this active region, with the ARTB previously observed by SXT and studied by Shimizu (1992). Within the simultaneous high cadence SOHO JOP 80 image sequences, both EIT and SXT accummulated a few tens of brightening events. At the time of the writing of this abstract, we can say that most of the SXT events have indeed 1 or more EIT counterparts. Typically the SXT events are somewhat bigger than the EIT events where the latter are ussualy located toward the point of origin of the SXT events. Whereas a few brightenings exist in one dataset without any trace in the other dataset (in both directions), we have additionally for a few brightenings in the SXT data, a corresponding EIT darkening as if the plasma is suddenly heated and dissappears from

  2. Dynamics and evolution of emerging active regions .

    NASA Astrophysics Data System (ADS)

    Battiato, V.; Billotta, S.; Contarino, L.; Romano, P.; Spadaro, D.; Zuccarello, F.

    In the framework of the study on active region emergence, we report the results obtained from the analysis of two ARs (NOAA 10050 and NOAA 10407), characterized by different lifetimes: recurrent the former and short-lived (7 days) the latter. The data used were acquired during two observational campaigns carried out at THEMIS telescope in IPM mode, coordinated with other instruments (IOACT, DOT, BBSO, MDI/SOHO, EIT/SOHO, TRACE). The results obtained have provided indications on the atmospheric layers where the first manifestations of the emerging AR are evidenced, on the rate of emergence of magnetic flux, on the upward velocity of AFS, on asymmetries in downward motions in the AFS legs.

  3. FIP bias in a sigmoidal active region

    NASA Astrophysics Data System (ADS)

    Baker, D.; Brooks, D. H.; Démoulin, P.; van Driel-Gesztelyi, Lidia; Green, L. M.; Steed, K.; Carlyle, J.

    2014-01-01

    We investigate first ionization potential (FIP) bias levels in an anemone active region (AR) - coronal hole (CH) complex using an abundance map derived from Hinode/EIS spectra. The detailed, spatially resolved abundance map has a large field of view covering 359'' × 485''. Plasma with high FIP bias, or coronal abundances, is concentrated at the footpoints of the AR loops whereas the surrounding CH has a low FIP bias, ~1, i.e. photospheric abundances. A channel of low FIP bias is located along the AR's main polarity inversion line containing a filament where ongoing flux cancellation is observed, indicating a bald patch magnetic topology characteristic of a sigmoid/flux rope configuration.

  4. Thermal equilibrium and temperature differences among body regions in European plethodontid salamanders.

    PubMed

    Lunghi, Enrico; Manenti, Raoul; Canciani, Giancarlo; Scarì, Giorgio; Pennati, Roberta; Ficetola, Gentile Francesco

    2016-08-01

    Information on species thermal physiology is extremely important to understand species responses to environmental heterogeneity and changes. Thermography is an emerging technology that allows high resolution and accurate measurement of body temperature, but until now it has not been used to study thermal physiology of amphibians in the wild. Hydromantes terrestrial salamanders are strongly depending on ambient temperature for their activity and gas exchanges, but information on their body temperature is extremely limited. In this study we tested if Hydromantes salamanders are thermoconform, we assessed whether there are temperature differences among body regions, and evaluated the time required to reach the thermal equilibrium. During summers of 2014 and 2015 we analysed 56 salamanders (Hydromantes ambrosii and Hydromantes italicus) using infrared thermocamera. We photographed salamanders at the moment in which we found them and 1, 2, 3, 4, 5 and 15min after having kept them in the hands. Body temperature was equal to air temperature; salamanders attained the equilibrium with air temperature in about 8min, the time required to reach equilibrium was longer in individuals with large body size. We detected small temperature differences between body parts, the head being slightly warmer than the body and the tail (mean difference: 0.05°C). These salamanders quickly reach the equilibrium with the environment, thus microhabitat measurement allows obtaining accurate information on their tolerance limits.

  5. Active region helicity evolution and related coronal mass ejection activity.

    NASA Astrophysics Data System (ADS)

    Green, L.; Mandrini, C.; van Driel-Gesztelyi, L.; Demoulin, P.

    The computation of magnetic helicity has become increasingly important in the studies of solar activity. Observations of helical structures in the solar atmosphere, and their subsequent ejection into the interplanetary medium, have resulted in considerable interest to find the link between the amount of helicity in the coronal magnetic field and the origin of coronal mass ejections (CMEs). This is reinforced by theory which shows magnetic helicity to be a well preserved quantity (Berger, 1984), and so with a continued injection into the corona an endless accumulation will occur. CMEs therefore provide a natural method to remove helicity from the corona. Recent works (DeVore, 2000, Chae, 2001, Chae et al., 2001, Demoulin et al., 2002, Green et al., 2002) have endeavoured to find the source of helicity in the corona to explain the observed CME activity in specific cases. The main candidates being differential rotation, shear motions or a transfer of helicity from below the photosphere into the corona. In order to establish a confident relation between CMEs and helicity, these works needs to be expanded to include CME source regions with different characteristics. A study of a very different active region will be presented and the relationship between helicity content and CME activity will be discussed in the framework of the previous studies.

  6. Concentration and temperature effects on ovostatin activity

    NASA Technical Reports Server (NTRS)

    Moriarity, Debra M.

    1994-01-01

    Light scattering experiments performed at Mississippi State University using MSFC ovostatin preparations indicated that at low ovostatin concentrations, below 0.2 mg/ml, the protein was dissociating from a tetramer into dimers. Since the proposed mechanism of action involved the tetrameric form of the protein, we hypothesized that perhaps under the conditions of our assays at various O/T ratios the ovostatin was becoming dissociated into an inactive dimer. To examine this possibility we assayed the ovostatin activity as a function of ovostatin concentration and of temperature of the assay. Data are presented that show the results of these assays at 23 C, 30 C, 37 C and 42 C respectively. The data are highly suggestive that there is a decrease in ovostatin activity as the concentration of the protein falls below 0.06 mg/ml. This may not be of any physiological importance, however, since the concentration of ovostatin in the egg is about 0.5 mg/ml. Curiously, the dissociation of the tetramer into dimers does not show a significant temperature dependence as would be expected for an equilibrium reaction. Whether this is in fact the case, or whether the differences are so small as to not be discerned from the current data remains to be seen. Another aspect to consider is that in the egg the primary role of the ovostatin may or may not be as a protease inhibitor. Although the inhibition of collagenase by ovostatin may be an important aspect of embryogenesis, it is also possible that it functions as a binding protein for some substance. In this regard, all ovostatin preparations from MSFC have shown an approximately 88,000 MW protein associated with the ovostatin. The identity of this protein is not currently known and may be the subject of future studies.

  7. Air-sea interactions in sea surface temperature frontal region

    NASA Astrophysics Data System (ADS)

    Pianezze, Joris; Redelsperger, Jean-Luc; Ardhuin, Fabrice; Reynaud, Thierry; Marié, Louis; Bouin, Marie-Noelle; Garnier, Valerie

    2015-04-01

    Representation of air-sea exchanges in coastal, regional and global models represent a challenge firstly due to the small scale of acting turbulent processes comparatively to the resolved scales of these models. Beyond this subgrid parameterization issue, a comprehensive understanding of air-sea interactions at the turbulent process scales is still lacking. Many successful efforts are dedicated to measure the energy and mass exchanges between atmosphere and ocean, including the effect of surface waves. In comparison less efforts are brought to understand the interactions between the atmospheric boundary layer and the oceanic mixing layer. In this regard, we are developing research mainly based on ideal and realistic numerical simulations which resolve very small scales (horizontal resolutions from 1 to 100 meters) in using grid nesting technics and coupled ocean-wave-atmosphere models. As a first step, the impact of marked gradients in sea surface temperatures (SST) on air-sea exchanges has been explored through realistic numerical simulations at 100m horizontal resolution. Results from simulations of a case observed during the FROMVAR experiment will be shown. The talk will mainly focus on the marked impact of SST front on the atmospheric boundary layer (stability and winds), the air-sea exchanges and surface parameters (rugosity, drag coefficient) Results will be also shown on the strong impact on the simulated atmosphere of small scale variability of SST field.

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

    NASA Technical Reports Server (NTRS)

    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.

  9. Surface temperatures in the polar regions from Nimbus 7 temperature humidity infrared radiometer

    NASA Technical Reports Server (NTRS)

    Comiso, Josefino C.

    1994-01-01

    Monthly surface temperatures in the Arctic and Antarctic regions have been derived from the 11.5 micrometer thermal infrared channel of the Nimbus 7 temperature humidity infrared radiometer (THIR) for a whole year in 1979 and for a winter and a summer month from 1980 through 1985. The data set shows interannual variability and provides spatial details that allow identification of temperature patterns over sea ice and ice sheet surfaces. For example, the coldest spot in the southern hemisphere is observed to be consistently in the Antarctic plateau in the southern hemisphere, while that in the northern hemisphere is usually located in Greenland, or one of three other general areas: Siberia, the central Arctic, or the Canadian Archipelago. Also, in the southern hemisphere, the amplitude of the seasonal fluctuation of ice sheet temperatures is about 3 times that of sea ice, while in the northern hemisphere, the corresponding fluctuations for the two surfaces are about the same. The main sources of error in the retrieval are cloud and other atmospheric effects. These were minimized by first choosing the highest radiance value from the set of measurements during the day taken within a 30 km by 30 km grid of each daily map. Then the difference of daily maps was taken and where the difference is greater than a certain threshold (which in this case is 12 C), the data element is deleted. Overall, the monthly maps derived from the resulting daily maps are spatially and temporally consistent, are coherent with the topograph y of the Antarctic continent and the location of the sea ice edge, and are in qualitative agreement with climatological data. Quantitatively, THIR data are in good agreement with Antarctic ice sheet surface air temperature station data with a correlation coefficient of 0.997 and a standard deviation of 2.0 C. The absolute values are not as good over the sea ice edges, but a comparison with Russian 2-m drift station temperatures shows very high correlation

  10. Implications of Special Regions to Conducting Human Activities on Mars

    NASA Astrophysics Data System (ADS)

    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.

  11. The anomalous Mesopause region temperatures of the 2003-2004 winter season measured from Svalbard (78N 16E)

    NASA Astrophysics Data System (ADS)

    Dyrland, M. E.; Sigernes, F.; Mulligan, F.; Deehr, C. S.

    2007-12-01

    This paper reports on the temperature and dynamics of the hydroxyl layer at approx. 87km measured over Longyearbyen (78N 16E) during the 2003-2004 winter. Optical spectra obtained by a Ebert-Fastie spectrometer were used for the temperature derivation. The high number of spectra available enabled spectral analysis of both the hourly and daily averaged temperatures. We were able to identify both the presence of a 16 day wave and a quasi 27 day oscillation in the mesopause region (approx. 87 km) temperatures from this season. The average daily temperature was 228K with a standard deviation of 17K. This is exceptionally high compared to previous and later years reported in the 23 year old time series from Svalbard. The observed temperatures have been compared to temperature data from other height regions above the Arctic (troposphere and stratosphere) and to satellite data from the satellite instrument SABER. In early January 2004 a major stratospheric warming event led to a nearly 2 month long vortex disruption with high-latitude easterlies in the middle to lower stratosphere and correspondingly high temperatures. The upper stratospheric temperatures of the same period were unusually low, while mesopause temperatures were high. The regions of alternating low and high temperatures throughout the atmosphere and the dynamics of these, are clearly coupled through gravity wave activity and general atmospheric circulation. We try to put our data into context with other authors' reports on the anomalous state of the atmosphere during the 2003-2004 boreal winter.

  12. Does temperature nudging overwhelm aerosol radiative effects in regional integrated climate models?

    NASA Astrophysics Data System (ADS)

    He, Jian; Glotfelty, Timothy; Yahya, Khairunnisa; Alapaty, Kiran; Yu, Shaocai

    2017-04-01

    Nudging (data assimilation) is used in many regional integrated meteorology-air quality models to reduce biases in simulated climatology. However, in such modeling systems, temperature changes due to nudging could compete with temperature changes induced by radiatively active and hygroscopic short-lived tracers leading to two interesting dilemmas: when nudging is continuously applied, what are the relative sizes of these two radiative forces at regional and local scales? How do these two forces present in the free atmosphere differ from those present at the surface? This work studies these two issues by converting temperature changes due to nudging into pseudo radiative effects (PRE) at the surface (PRE_sfc), in troposphere (PRE_atm), and at the top of atmosphere (PRE_toa), and comparing PRE with the reported aerosol radiative effects (ARE). Results show that the domain-averaged PRE_sfc is smaller than ARE_sfc estimated in previous studies and this work, but could be significantly larger than ARE_sfc at local scales. PRE_atm is also much smaller than ARE_atm. These results indicate that appropriate nudging methodology could be applied to the integrated models to study aerosol radiative effects at continental/regional scales, but it should be treated with caution for local scale applications.

  13. The Limit of Free Magnetic Energy in Active Regions

    NASA Technical Reports Server (NTRS)

    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.

  14. Regional projection of Temperature for the 21st Century over the Eastern India

    NASA Astrophysics Data System (ADS)

    Dhage, Pradnya; Singh Raghuwanshi, Narendra; Singh, Rajendra

    2016-04-01

    Global as well as regional climate has changed due to human activities like land use changes, production of industrial effluents and other developmental activities of the society. The consequences of these changes have a massive impact on atmospheric events like precipitation, temperature etc. The rainfall and temperature are intrinsic parameters of hydrologic cycle. Consequently, these are also the major driving factors of change in hydrologic response due to climate change. Future temperature information is required at regional and basin scales for climate change studies. Therefore, in present study, daily maximum (Tmax) and minimum (Tmin) temperatures scenarios were developed from Multi-GCM ensemble (CanESM2, IPSL-CM5A-LR, MPI-ESM-LR, and CNRM-CM5 GCMs) using bias correction and spatial downscaling (BCSD) method at station scale for Kangsabati reservoir catchment and command, West Bengal, India. Subsequently, temperature intensity and frequency indices like extremes of maximum and minimum temperatures, consecutive hot days, consecutive cold days, and warming nights were analyzed. The GCM data for all the requisite variables corresponding to historic run (1971-2005) and future climate (2006-2100) were used under Representative Concentration Pathway (RCP4.5 and RCP8.5) emission scenarios. The results indicate significant increase in maximum and minimum temperatures in all seasons (pre-monsoon, monsoon, and post-monsoon), with the most significant increase occurring in pre-monsoon season, and for all the stations of the study area. The warming tendencies of maximum and minimum temperatures over the Kangsabati command area are projected as 0.20 and 0.22 °C/decade under RCP4.5, and 0.54 and 0.59 °C/decade under RCP8.5 for 2011-2100 period, respectively. Further, it is found that the temperature intensity and frequency indices will increase (maximum value of Tmax and Tmin, and minimum value of Tmax and Tmin, consecutive hot days, and warming nights) while

  15. Temperature Icreasing Trend During Recent Four Decades At Riyadh Region

    NASA Astrophysics Data System (ADS)

    Almleaky, Y.; Sharaf, M.; Basurah, H.; Malawi, A.; Euony, S.

    In this paper the data analysis of one element of the meteorological data of old Riyadh, namely air temperature will be discussed. This station is located on the middle province of the Kingdom of Saudi Arabia and of coordinates (46.72 E and 24.65 N). The analysis of each of the global maximum and, the global minimum temperature is given for each year through out five points: its value, the date of occurrence, the day of the year and the Julian day, finally, the day of the year. Some statistics are provided for the smoothed values of the mean daily variation of the air temperature. We finally addressed some graphical representations, e.g. histograms, daily variations with their fitting equation. A preliminary conclusion indicating that there are general increasing trend in the temperature during the recent thirty four years.

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

    NASA Astrophysics Data System (ADS)

    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. Compact sources of suprathermal microwave emission detected in quiescent active regions during lunar occultations

    NASA Astrophysics Data System (ADS)

    Correia, E.; Kaufmann, P.; Strauss, F. M.

    1992-04-01

    Solar quiescent active regions are known to exhibit radio emission from discrete structures. The knowledge of their dimensions and brightness temperatures is essential for understanding the physics of quiescent, confined plasma regions. Solar eclipses of 10 August, 1980 and 26 January, 1990, observed with high sensitivity and high time resolution at 22 GHz, allowed an unprecedented opportunity to identify Fresnel diffraction effects during lunar occultations of active regions. The results indicate the presence of quiescent discrete sources smaller than one arcsec in one dimension. Assuming symmetrical sources, their brightness temperatures were larger than 2 x 10 exp 7 K and 8 x 10 exp 7 K, for the 1980 and 1990 observations, respectively.

  18. "The Effect of Alternative Representations of Lake Temperatures and Ice on WRF Regional Climate Simulations"

    EPA Science Inventory

    Lakes can play a significant role in regional climate, modulating inland extremes in temperature and enhancing precipitation. Representing these effects becomes more important as regional climate modeling (RCM) efforts focus on simulating smaller scales. When using the Weathe...

  19. Temporal evolution of continental lithospheric strength in actively deforming regions

    USGS Publications Warehouse

    Thatcher, W.; Pollitz, F.F.

    2008-01-01

    It has been agreed for nearly a century that a strong, load-bearing outer layer of earth is required to support mountain ranges, transmit stresses to deform active regions and store elastic strain to generate earthquakes. However the dept and extent of this strong layer remain controversial. Here we use a variety of observations to infer the distribution of lithospheric strength in the active western United States from seismic to steady-state time scales. We use evidence from post-seismic transient and earthquake cycle deformation reservoir loading glacio-isostatic adjustment, and lithosphere isostatic adjustment to large surface and subsurface loads. The nearly perfectly elastic behavior of Earth's crust and mantle at the time scale of seismic wave propagation evolves to that of a strong, elastic crust and weak, ductile upper mantle lithosphere at both earthquake cycle (EC, ???10?? to 103 yr) and glacio-isostatic adjustment (GIA, ???103 to 104 yr) time scales. Topography and gravity field correlations indicate that lithosphere isostatic adjustment (LIA) on ???106-107 yr time scales occurs with most lithospheric stress supported by an upper crust overlying a much weaker ductile subtrate. These comparisons suggest that the upper mantle lithosphere is weaker than the crust at all time scales longer than seismic. In contrast, the lower crust has a chameleon-like behavior, strong at EC and GIA time scales and weak for LIA and steady-state deformation processes. The lower crust might even take on a third identity in regions of rapid crustal extension or continental collision, where anomalously high temperatures may lead to large-scale ductile flow in a lower crustal layer that is locally weaker than the upper mantle. Modeling of lithospheric processes in active regions thus cannot use a one-size-fits-all prescription of rheological layering (relation between applied stress and deformation as a function of depth) but must be tailored to the time scale and tectonic

  20. Behavior of plane waves propagating through a temperature-inhomogeneous region

    NASA Astrophysics Data System (ADS)

    Bednarik, M.; Cervenka, M.; Lotton, P.; Penelet, G.

    2016-02-01

    Description and analysis of acoustic waves in ducts with a region containing temperature-inhomogeneous fluid represent a significant problem of scientific and practical interest. This interest is induced by the need of understanding how temperature fields affect acoustic processes which would lead to a more efficient design and control of systems involving thermoacoustic interactions. Most of the works addressing these problems limit themselves to the assumption of weak temperature profile gradients or to temperature profiles which do not connect neighboring temperature-homogeneous regions smoothly. In our work we investigate the behavior of plane acoustic waves that enter a region with an arbitrary temperature gradient. A polynomial character of the used temperature profile ensures smooth connection with constant-temperature regions. The one-dimensional wave equation for ducts with an axial mean temperature gradient is solved analytically. The derived solutions based on Heun functions extend the class of published exact analytical solutions of model wave equations taking into account the medium temperature gradient. Due to the property that our proposed polynomial temperature function has derivatives equal to zero at points which are connected with the surrounding temperature-homogeneous regions we can form more complex smooth temperature profiles for which it is possible to use the transfer matrix method.

  1. Water-temperature data acquisition activities in the United States

    USGS Publications Warehouse

    Pauszek, F.H.

    1972-01-01

    Water Data Coordination, U.S. Geological Survey, and published in the "Catalog of Information on Water Data, Index to Water Quality Section, Edition 1970." This is one of four indexes, each of which is a separate section of the Catalog. Three of the indexes, "Index to Water-Quality Section," "Index to Surface-Water Section," and "Index to Ground-.Water Stations," contain information on data acquired on a recurrent basis at specific locations for a period of 3 years or more. The fourth section, "Index to Areal Investigations and Miscellaneous Activities," is concerned with specific projects or shorter-term data activities that involve field or laboratory measurements or observations not included in any other section of the Catalog. The Catalog is a record of activities throughout the country (and in some places along the international border between the United States and Canada) conducted by Federal and non-Federal agencies engaged in the acquisition of water data and who furnish such information for presentation in the Catalog. The Catalog itself is an outgrowth of an assignment to the Department of the Interior and in turn to the Geological Survey, by the Office of Management and Budget, through the medium of OMB Circular A-67. This Circular states in part that one of the assigned responsibilities will be maintenance of a "central catalog of information on...water data and on Federal activities being planned or conducted to acquire such data." As an extension of this activity, non-Federal agencies are solicited to participate in the program. In this report, information is presented by means of tables and illustrations preceded by brief explanations. It includes the agencies collecting the data, the number of stations located on surface and ground waters where temperature measurements are made, the distribution of stations by States and by the 21 regions of the Water Resources Council (WRC) (a Federal agency created in accordance with the Water Resources Planning Act of

  2. Holocene fire activity in the Carpathian region: regional climate vs. local controls

    NASA Astrophysics Data System (ADS)

    Florescu, Gabriela; Feurdean, Angelica

    2015-04-01

    Introduction. Fire drives significant changes in ecosystem structure and function, diversity, species evolution, biomass dynamics and atmospheric composition. Palaeodata and model-based studies have pointed towards a strong connection between fire activity, climate, vegetation and people. Nevertheless, the relative importance of these factors appears to be strongly variable and a better understanding of these factors and their interaction needs a thorough investigation over multiple spatial (local to global) and temporal (years to millennia) scales. In this respect, sedimentary charcoal, associated with other proxies of climate, vegetation and human impact, represents a powerful tool of investigating changes in past fire activity, especially in regions with scarce fire dataset such as the CE Europe. Aim. To increase the spatial and temporal coverage of charcoal records and facilitate a more critical examination of the patterns, drivers and consequences of biomass burning over multiple spatial and temporal scales in CE Europe, we have investigated 6 fossil sequences in the Carpathian region (northern Romania). These are located in different geographical settings, in terms of elevation, vegetation composition, topography and land-use. Specific questions are: i) determine trends in timing and magnitude of fire activity, as well as similarities and differences between elevations; ii) disentangle the importance of regional from local controls in fire activity; iii) evaluate ecological consequences of fire on landscape composition, structure and diversity. Methods. We first determine the recent trends in fire activity (the last 150 years) from charcoal data and compare them with instrumental records of temperature, precipitation, site history and topography for a better understanding of the relationship between sedimentary charcoal and historical fire activity. We then statistically quantify centennial to millennial trends in fire activity (frequency, magnitude) based on

  3. Technique for inferring sizes of stellar-active regions

    SciTech Connect

    Dobson-Hockey, A.K.; Radick, R.R.

    1986-01-01

    Inspection of spectroheliograms showing large, well-developed active regions generally show the sunspots to lead the associated plage, in the sense of the solar rotation. Measurements have been made from spectroheliograms of spot-plage offsets and compared with nearly contemporaneous integrated disk observations. Larger active regions generally show larger spot leads; however, information regarding active-region sizes and spot-plage offsets is not readily obtainable form stellar-type observations of the Sun.

  4. Tracked Active Region Patches for MDI and HMI

    NASA Astrophysics Data System (ADS)

    Turmon, Michael; Hoeksema, J. Todd; Bobra, Monica

    2014-06-01

    We describe tracked active-region patch data products that have been developed for HMI (HMI Active Region Patches, or HARPs) and for MDI (MDI Tracked Active Region Patches, or MDI TARPs). Both data products consist of tracked magnetic features on the scale of solar active regions. The now-released HARP data product covers 2010-present (>2000 regions to date). Like the HARPs, the MDI TARP data set is a catalog of active regions (ARs), indexed by a region ID number, analogous to a NOAA AR number, and time. The TARPs contain 6170 regions spanning 72000 images taken over 1996-2010, and will be availablein the MDI resident archive (RA).MDI TARPs are computed based on the 96-minute synoptic magnetograms and intensitygrams. As with the related HARP data product, the approximate threshold for significance is 100G. Use of both image types together allows faculae and sunspots to be separated out as sub-classes of activity, in addition to identifying the overall active region that they are in. After being identified in single images, the magnetically-active patches are grouped and tracked from image to image. Merges among growing active regions, as well as faint active regions hovering at the threshold of detection, are handled automatically. Regions are tracked from their inception until they decay within view, or transit off the visible disk. For each active region and for each time, a bitmap image is stored containing the precise outline of the active region. Also, metadata such as areas and integrated fluxes are stored for each AR and for each time. Because there is a cross-calibration between the HMI and MDI magnetograms (Liu et al. 2012), it is straightforward to use the same classification and tracking rules for the HMI HARPs and the MDI TARPs. We show results demonstrating region correspondence, region boundary agreement, and agreement of flux metadata using the approximately 140 regions in the May 2010-October 2010 time period. We envision several uses for these data

  5. Evaluating geothermal and hydrogeologic controls on regional groundwater temperature distribution

    NASA Astrophysics Data System (ADS)

    Burns, Erick R.; Ingebritsen, Steven E.; Manga, Michael; Williams, Colin F.

    2016-02-01

    A one-dimensional (1-D) analytic solution is developed for heat transport through an aquifer system where the vertical temperature profile in the aquifer is nearly uniform. The general anisotropic form of the viscous heat generation term is developed for use in groundwater flow simulations. The 1-D solution is extended to more complex geometries by solving the equation for piece-wise linear or uniform properties and boundary conditions. A moderately complex example, the Eastern Snake River Plain (ESRP), is analyzed to demonstrate the use of the analytic solution for identifying important physical processes. For example, it is shown that viscous heating is variably important and that heat conduction to the land surface is a primary control on the distribution of aquifer and spring temperatures. Use of published values for all aquifer and thermal properties results in a reasonable match between simulated and measured groundwater temperatures over most of the 300 km length of the ESRP, except for geothermal heat flow into the base of the aquifer within 20 km of the Yellowstone hotspot. Previous basal heat flow measurements (˜110 mW/m2) made beneath the ESRP aquifer were collected at distances of >50 km from the Yellowstone Plateau, but a higher basal heat flow of 150 mW/m2 is required to match groundwater temperatures near the Plateau. The ESRP example demonstrates how the new tool can be used during preliminary analysis of a groundwater system, allowing efficient identification of the important physical processes that must be represented during more-complex 2-D and 3-D simulations of combined groundwater and heat flow.

  6. Evaluating geothermal and hydrogeologic controls on regional groundwater temperature distribution

    USGS Publications Warehouse

    Burns, Erick R.; Ingebritsen, Steven E.; Manga, Michael; Williams, Colin F.

    2016-01-01

    A one-dimensional (1-D) analytic solution is developed for heat transport through an aquifer system where the vertical temperature profile in the aquifer is nearly uniform. The general anisotropic form of the viscous heat generation term is developed for use in groundwater flow simulations. The 1-D solution is extended to more complex geometries by solving the equation for piece-wise linear or uniform properties and boundary conditions. A moderately complex example, the Eastern Snake River Plain (ESRP), is analyzed to demonstrate the use of the analytic solution for identifying important physical processes. For example, it is shown that viscous heating is variably important and that heat conduction to the land surface is a primary control on the distribution of aquifer and spring temperatures. Use of published values for all aquifer and thermal properties results in a reasonable match between simulated and measured groundwater temperatures over most of the 300 km length of the ESRP, except for geothermal heat flow into the base of the aquifer within 20 km of the Yellowstone hotspot. Previous basal heat flow measurements (∼110 mW/m2) made beneath the ESRP aquifer were collected at distances of >50 km from the Yellowstone Plateau, but a higher basal heat flow of 150 mW/m2 is required to match groundwater temperatures near the Plateau. The ESRP example demonstrates how the new tool can be used during preliminary analysis of a groundwater system, allowing efficient identification of the important physical processes that must be represented during more-complex 2-D and 3-D simulations of combined groundwater and heat flow.

  7. A Fractal Dimension Survey of Active Region Complexity

    NASA Technical Reports Server (NTRS)

    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 .

  8. GLOBAL DYNAMICS OF SUBSURFACE SOLAR ACTIVE REGIONS

    SciTech Connect

    Jouve, L.; Brun, A. S.

    2013-01-01

    We present three-dimensional numerical simulations of a magnetic loop evolving in either a convectively stable or unstable rotating shell. The magnetic loop is introduced into the shell in such a way that it is buoyant only in a certain portion in longitude, thus creating an {Omega}-loop. Due to the action of magnetic buoyancy, the loop rises and develops asymmetries between its leading and following legs, creating emerging bipolar regions whose characteristics are similar to those of observed spots at the solar surface. In particular, we self-consistently reproduce the creation of tongues around the spot polarities, which can be strongly affected by convection. We further emphasize the presence of ring-shaped magnetic structures around our simulated emerging regions, which we call 'magnetic necklace' and which were seen in a number of observations without being reported as of today. We show that those necklaces are markers of vorticity generation at the periphery and below the rising magnetic loop. We also find that the asymmetry between the two legs of the loop is crucially dependent on the initial magnetic field strength. The tilt angle of the emerging regions is also studied in the stable and unstable cases and seems to be affected both by the convective motions and the presence of a differential rotation in the convective cases.

  9. Active region coronal loops observed at the total solar eclipse of February 16, 1980

    NASA Astrophysics Data System (ADS)

    Hanaoka, Yoishiro; Kurokawa, Hiroki; Saito, Sumisaburo

    Coronal loop structures above an active region observed at the total eclipse of February 16, 1980 in Kenya are analyzed. Temperatures and densities of the loops are derived from three monochromatic images of Fe X λ6374 (1×106K or cool corona), Fe XIV λ5303 (2×106K or hot corona), and continuum. These monochromatic images are processed for the analyses, and pure images of the active region corona are obtained. Results from a morphological diagnostics are presented.

  10. Energy Budget and Ground Temperatures in Hot Regions

    DTIC Science & Technology

    1988-06-01

    and evapotranspiration are not important in the dry season in the Sinai. Measurements show that both the clumps of plants and the bare soil have... evapotranspiration is strong, and a large portion of incident solar energy becomes latent heat. Measurements in Senegal in the sub-Sanaran region of Africa show...cannot be dense without some minimum amount of available moisture, evapotranspiration is not totally negligible in any season in the area with densest

  11. Temperature diagnostics for carbon IV ion by using a collision model in the solar transition region

    NASA Astrophysics Data System (ADS)

    Liao, Lamei; He, Jian; Zhang, Qingguo

    2016-09-01

    For spectral diagnostics of temperature in the solar transition region, by using a semi-classical method, we calculate the collision strengths for the dipole transition of carbon IV 2S1/2-2P1/2 and 2S1/2-2P3/2, and we discuss the Maxwellian-averaged collision strengths for a wide temperature region. Then, based on the Maxwellian-averaged collision strengths, we discuss the spectral diagnostic of temperature in the solar transition region and obtain the temperature T = 1.7 × 105 K for the carbon IV ion in that region, which is in good agreement with the predicted temperature range of 1.0 × 105 K to 2.0 × 105 K. This calculation will be significant for spectral diagnostics in the solar transition region.

  12. Universal behavior of the viscosity of supercooled fragile and polymeric glassformers in different temperature regions

    NASA Astrophysics Data System (ADS)

    Andraca, Adriana; Goldstein, Patricia; del Castillo, Luis Felipe

    2016-11-01

    The behavior of the viscosity of supercooled liquids with temperature has been extensively studied in different regimes. We present a universal behavior for the Logarithmic Shift Factor for fragile and polymeric glassformers in two temperature regions, above and below the crossover temperature Tc, respectively. We find two different equations, one for each region, that may be represented as master plots which show universal behaviors for both cases.

  13. Photonic crystal lasers using wavelength-scale embedded active region

    NASA Astrophysics Data System (ADS)

    Matsuo, Shinji; Sato, Tomonari; Takeda, Koji; Shinya, Akihiko; Nozaki, Kengo; Kuramochi, Eiichi; Taniyama, Hideaki; Notomi, Masaya; Fujii, Takuro; Hasebe, Koichi; Kakitsuka, Takaaki

    2014-01-01

    Lasers with ultra-low operating energy are desired for use in chip-to-chip and on-chip optical interconnects. If we are to reduce the operating energy, we must reduce the active volume. Therefore, a photonic crystal (PhC) laser with a wavelength-scale cavity has attracted a lot of attention because a PhC provides a large Q-factor with a small volume. To improve this device's performance, we employ an embedded active region structure in which the wavelength-scale active region is buried with an InP PhC slab. This structure enables us to achieve effective confinement of both carriers and photons, and to improve the thermal resistance of the device. Thus, we have obtained a large external differential quantum efficiency of 55% and an output power of -10 dBm by optical pumping. For electrical pumping, we use a lateral p-i-n structure that employs Zn diffusion and Si ion implantation for p-type and n-type doping, respectively. We have achieved room-temperature continuous-wave operation with a threshold current of 7.8 µA and a maximum 3 dB bandwidth of 16.2 GHz. The results of an experimental bit error rate measurement with a 10 Gbit s-1 NRZ signal reveal the minimum operating energy for transferring a single bit of 5.5 fJ. These results show the potential of this laser to be used for very short reach interconnects. We also describe the optimal design of cavity quality (Q) factor in terms of achieving a large output power with a low operating energy using a calculation based on rate equations. When we assume an internal absorption loss of 20 cm-1, the optimized coupling Q-factor is 2000.

  14. Oscillations in the Flaring Active Region NOAA 11272

    NASA Astrophysics Data System (ADS)

    Conde Cuellar, S. M.; Costa, J. E. R.; Cedeño Montaña, C. E.

    2016-11-01

    We studied waves seen during the class C1.9 flare that occurred in Active Region NOAA 11272 on SOL2011-08-17. We found standing waves with periods in the 9- and 19-minute band in six extreme ultraviolet (EUV) wavelengths of the SDO/AIA instrument. We succeeded in identifying the magnetic arc where the flare started and two neighbour loops that were disturbed in sequence. The analysed standing waves spatially coincide with these observed EUV loops. To study the wave characteristics along the loops, we extrapolated field lines from the line-of-sight magnetograms using the force-free approximation in the linear regime. We used atmosphere models to determine the mass density and temperature at each height of the loop. Then, we calculated the sound and Alfvén speeds using densities 108 ≲ ni ≲ 10^{17} cm^{-3} and temperatures 103 ≲ T ≲ 107 K. The brightness asymmetry in the observed standing waves resembles the Alfvén speed distribution along the loops, but the atmospheric model we used needs higher densities to explain the observed periods.

  15. Software Displays Data on Active Regions of the Sun

    NASA Technical Reports Server (NTRS)

    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

  16. Reading cinnamon activates olfactory brain regions.

    PubMed

    González, Julio; Barros-Loscertales, Alfonso; Pulvermüller, Friedemann; Meseguer, Vanessa; Sanjuán, Ana; Belloch, Vicente; Avila, César

    2006-08-15

    Some words immediately and automatically remind us of odours, smells and scents, whereas other language items do not evoke such associations. This study investigated, for the first time, the abstract linking of linguistic and odour information using modern neuroimaging techniques (functional MRI). Subjects passively read odour-related words ('garlic', 'cinnamon', 'jasmine') and neutral language items. The odour-related terms elicited activation in the primary olfactory cortex, which include the piriform cortex and the amygdala. Our results suggest the activation of widely distributed cortical cell assemblies in the processing of olfactory words. These distributed neuron populations extend into language areas but also reach some parts of the olfactory system. These distributed neural systems may be the basis of the processing of language elements, their related conceptual and semantic information and the associated sensory information.

  17. Protein stability and enzyme activity at extreme biological temperatures.

    PubMed

    Feller, Georges

    2010-08-18

    Psychrophilic microorganisms thrive in permanently cold environments, even at subzero temperatures. To maintain metabolic rates compatible with sustained life, they have improved the dynamics of their protein structures, thereby enabling appropriate molecular motions required for biological activity at low temperatures. As a consequence of this structural flexibility, psychrophilic proteins are unstable and heat-labile. In the upper range of biological temperatures, thermophiles and hyperthermophiles grow at temperatures > 100 °C and synthesize ultra-stable proteins. However, thermophilic enzymes are nearly inactive at room temperature as a result of their compactness and rigidity. At the molecular level, both types of extremophilic proteins have adapted the same structural factors, but in opposite directions, to address either activity at low temperatures or stability in hot environments. A model based on folding funnels is proposed accounting for the stability-activity relationships in extremophilic proteins.

  18. Development of MHD Wave Diagnostic and Models of Coronal Active Regions

    NASA Astrophysics Data System (ADS)

    Ofman, L.; Thompson, B. J.; Davila, J. M.

    2004-05-01

    We investigate the generation, propagation, and damping of MHD waves in active regions, with the goal to develop a diagnostic tool of active region structure, dynamics, and stability. We used 3D MHD model to study the generation and the propagation of EIT waves in a simple model of an active regions, and the interaction of EIT waves with the active region magnetic field. We model the oscillation of active region loops numerically using the 3D MHD model active regions. Such oscillations have been recently observed by TRACE. We use photospheric magnetograms as the boundary conditions for the magnetic field model, and construct an initial field using force-free extrapolation. Finite plasma temperature, density, and gravity are included in the model. We construct loop density structures in the model, guided by TRACE and EIT observations in the EUV. We demonstrate that by comparing the results of the MHD models of waves in an active region to observations we will be able to construct a diagnostic tool for the physical properties of the active regions, such as magnetic field and density structure.

  19. Geothermal and Hydrogeologic Controls on Regional Groundwater Temperatures

    NASA Astrophysics Data System (ADS)

    Burns, E. R.; Ingebritsen, S.; Williams, C. F.; Manga, M.

    2015-12-01

    A 1-D analytic solution for combined heat and groundwater flow through an aquifer system accounts for geothermal heating at the base of the aquifer, recharge of cooler water along the groundwater flow path, advection of heat within the aquifer, conduction of heat through the vadose zone, and viscous heating. The 1-D solution, which uses a freely available Python script, can be applied to moderately complex geometries by solving the heat flow equation for piece-wise linear or constant properties and boundary conditions. Analysis of the Eastern Snake River Plain regional aquifer system demonstrates that viscous heating, normally neglected by numerical solutions, is variably important along the groundwater flow path, and that heat conduction to the land surface and cool recharge are the primary thermal perturbations causing deviation from a steady, slow heating along the flow path. Because viscous heating is sometimes important, a general anisotropic form of the viscous heat-generation term has been derived and can be included in more complex 2-D and 3-D numerical solvers of the coupled heat and groundwater flow equations. The 1-D solution allows quick and easy determination of whether this term needs to be included. The rate at which thermal perturbations equilibrate with distance is controlled by the Peclet Number (the ratio of advective to conductive heat transport), which can be used to estimate the distance over which thermal perturbations (e.g., cool recharge or local geothermal hotspots) will be detectable.

  20. Regional Skin Temperature Response to Moderate Aerobic Exercise Measured by Infrared Thermography

    PubMed Central

    Fernandes, Alex de Andrade; Amorim, Paulo Roberto dos Santos; Brito, Ciro José; Sillero-Quintana, Manuel; Bouzas Marins, João Carlos

    2016-01-01

    Background: Infrared thermography (IRT) does not require contact with the skin, and it is a convenient, reliable and non-invasive technique that can be used for monitoring the skin temperature (TSK). Objectives: The aim of this study was to monitor the variations in the regional TSK during exercise on 28 regions of interest (ROIs) (forehead, face, chest, abdomen, back, lumbar, anterior and posterior neck, and posterior and anterior views of the right and left hands, forearms, upper arms, thighs, and legs) with IRT. Patients and Methods: 12 physically active young males were monitored with IRT during the following three phases: a) 30 minutes before exercise b) while performing one hour of moderate intensity exercise on a treadmill at 60% of the VO2max, and c) 60 minutes after exercise. Results: During pre-exercise, all TSK reached a steady-state (P ≤ 0.05), which ensured adequate thermal stabilisation. At the beginning of exercise, there was a significant reduction in the TSK in most ROIs after 10 minutes of activity, except for the lower limbs (legs and thighs). After one hour of recovery, in the anterior view of the hands and thighs and in the posterior view of the legs, there were significant increases in the TSK compared to pre-exercise. Conclusions: There were significant distinctions in the skin temperature distribution during exercise according to the activity of the area under consideration during exercise, which may be important in the development of physiological models and heat flux analyses for different purposes. PMID:27217931

  1. Temperature and Structure of Active Eruptions from a Handheld Camcorder

    NASA Astrophysics Data System (ADS)

    Radebaugh, Jani; Carling, Greg T.; Saito, Takeshi; Dangerfield, Anne; Tingey, David G.; Lorenz, Ralph D.; Lopes, Rosaly M.; Howell, Robert R.; Diniega, Serina; Turtle, Elizabeth P.

    2014-11-01

    A commercial handheld digital camcorder can operate as a high-resolution, short-wavelength, low-cost thermal imaging system for monitoring active volcanoes, when calibrated against a laboratory heated rock of similar composition to the given eruptive material. We utilize this system to find full pixel brightness temperatures on centimeter scales at close but safe proximity to active lava flows. With it, observed temperatures of a Kilauea tube flow exposed in a skylight reached 1200 C, compared with pyrometer measurements of the same flow of 1165 C, both similar to reported eruption temperatures at that volcano. The lava lake at Erta Ale, Ethiopia had crack and fountain temperatures of 1175 C compared with previous pyrometer measurements of 1165 C. Temperature calibration of the vigorously active Marum lava lake in Vanuatu is underway, challenges being excessive levels of gas and distance from the eruption (300 m). Other aspects of the fine-scale structure of the eruptions are visible in the high-resolution temperature maps, such as flow banding within tubes, the thermal gradient away from cracks in lake surfaces, heat pathways through pahoehoe crust and temperature zoning in spatter and fountains. High-resolution measurements such as these reveal details of temperature, structure, and change over time at the rapidly evolving settings of active lava flows. These measurement capabilities are desirable for future instruments exploring bodies with active eruptions like Io, Enceladus and possibly Venus.

  2. ACTIVE REGION MORPHOLOGIES SELECTED FROM NEAR-SIDE HELIOSEISMIC DATA

    SciTech Connect

    MacDonald, G. A.; McAteer, R. T. J.; Henney, C. J.; Arge, C. N.; Díaz Alfaro, M.; González Hernández, I.; Lindsey, C.

    2015-07-01

    We estimate the morphology of near-side active regions using near-side helioseismology. Active regions from two data sets, Air Force Data Assimilative Photospheric flux Transport synchronic maps and Global Oscillation Network Group near-side helioseismic maps, were matched and their morphologies compared. Our algorithm recognizes 382 helioseismic active regions between 2002 April 25 and 2005 December 31 and matches them to their corresponding magnetic active regions with 100% success. A magnetic active region occupies 30% of the area of its helioseismic signature. Recovered helioseismic tilt angles are in good agreement with magnetic tilt angles. Approximately 20% of helioseismic active regions can be decomposed into leading and trailing polarity. Leading polarity components show no discernible scaling relationship, but trailing magnetic polarity components occupy approximately 25% of the area of the trailing helioseismic component. A nearside phase-magnetic calibration is in close agreement with a previous far-side helioseismic calibration and provides confidence that these morphological relationships can be used with far-side helioseismic data. Including far-side active region morphology in synchronic maps will have implications for coronal magnetic topology predictions and solar wind forecasts.

  3. Active Region Morphologies Selected From Near-side Helioseismic Data

    NASA Astrophysics Data System (ADS)

    MacDonald, Gordon Andrew; Henney, Carl; Diaz Alfaro, Manuel; Gonzalez Hernandez, Irene; Arge, Nick; Lindsey, Charles; McAteer, James

    2015-04-01

    We estimate the morphology of near-side active regions using near-side helioseismology. Active regions from two data sets, ADAPT synchronic maps and GONG near-side helioseismic maps, were matched and their morphologies compared. Our algorithm recognizes 382 helioseismic active regions between 2002 April 25 and 2005 December 31 and matches them to their corresponding magnetic active regions with 100% success. A magnetic active region occupies 30% of the area of its helioseismic signature. Recovered helioseismic tilt angles are in good agreement with magnetic tilt angles. Approximately 20% of helioseismic active regions can be decomposed into leading and trailing polarity. Leading polarity components show no discernible scaling relationship, but trailing magnetic polarity components occupy approximately 25% of the area of the trailing helioseismic component. A nearside phase-magnetic calibration is in close agreement with a previous far-side helioseismic calibration and provides confidence that these morphological relationships can be used with far-side helioseismic data. Including far-side active region morphology in synchronic maps will have implications for coronal magnetic topology predictions and solar wind forecasts.

  4. Active Region Morphologies Selected from Near-side Helioseismic Data

    NASA Astrophysics Data System (ADS)

    MacDonald, G. A.; Henney, C. J.; Díaz Alfaro, M.; González Hernández, I.; Arge, C. N.; Lindsey, C.; McAteer, R. T. J.

    2015-07-01

    We estimate the morphology of near-side active regions using near-side helioseismology. Active regions from two data sets, Air Force Data Assimilative Photospheric flux Transport synchronic maps and Global Oscillation Network Group near-side helioseismic maps, were matched and their morphologies compared. Our algorithm recognizes 382 helioseismic active regions between 2002 April 25 and 2005 December 31 and matches them to their corresponding magnetic active regions with 100% success. A magnetic active region occupies 30% of the area of its helioseismic signature. Recovered helioseismic tilt angles are in good agreement with magnetic tilt angles. Approximately 20% of helioseismic active regions can be decomposed into leading and trailing polarity. Leading polarity components show no discernible scaling relationship, but trailing magnetic polarity components occupy approximately 25% of the area of the trailing helioseismic component. A nearside phase-magnetic calibration is in close agreement with a previous far-side helioseismic calibration and provides confidence that these morphological relationships can be used with far-side helioseismic data. Including far-side active region morphology in synchronic maps will have implications for coronal magnetic topology predictions and solar wind forecasts.

  5. Air- and stream-water-temperature trends in the Chesapeake Bay region, 1960-2014

    USGS Publications Warehouse

    Jastram, John D.; Rice, Karen C.

    2015-12-14

    Water temperature is a basic, but important, measure of the condition of all aquatic environments, including the flowing waters in the streams that drain our landscape and the receiving waters of those streams. Climatic conditions have a strong influence on water temperature, which is therefore naturally variable both in time and across the landscape. Changes to natural water-temperature regimes, however, can result in a myriad of effects on aquatic organisms, water quality, circulation patterns, recreation, industry, and utility operations. For example, most species of fish, insects, and other organisms, as well as aquatic vegetation, are highly dependent on water temperature. Warming waters can result in shifts in floral and faunal species distributions, including invasive species and pathogens previously unable to inhabit the once cooler streams. Many chemical processes are temperature dependent, with reactions occurring faster in warmer conditions, leading to degraded water quality as contaminants are released into waterways at greater rates. Circulation patterns in receiving waters, such as bays and estuaries, can change as a result of warmer inflows from streams, thereby affecting organisms in those receiving waters. Changes in abundance of some aquatic species and (or) degradation of water quality can reduce the recreational value of water bodies as waters are perceived as less desirable for water-related activities or as sportfish become less available for anglers. Finally, increasing water temperatures can affect industry and utilities as the thermal capacity is reduced, making the water less effective for cooling purposes.Chesapeake Bay is the largest estuary in the United States. Eutrophication, the enrichment of a water body with excess nutrients, has plagued the bay for decades and has led to extensive restoration efforts throughout the bay watershed. The warming of stream water can exacerbate eutrophication through increased release of nutrients from

  6. Low temperature and defoliation affect fructan-metabolizing enzymes in different regions of the rhizophores of Vernonia herbacea.

    PubMed

    Portes, Maria Teresa; Figueiredo-Ribeiro, Rita de Cássia L; de Carvalho, Maria Angela M

    2008-10-09

    In addition to the storage function, fructans in Asteraceae from floras with seasonal growth have been associated with drought and freezing tolerance. Vernonia herbacea, native of the Brazilian Cerrado, bears underground reserve organs, rhizophores, accumulating inulin-type fructans. The rhizophore is a cauline branched system with positive geotropic growth, with the apex (distal region) presenting younger tissues; sprouting of new shoots occurs by development of buds located on the opposite end (proximal region). Plants induced to sprouting by excision of the aerial organs present increased 1-fructan exohydrolase (1-FEH) activity in the proximal region, while plants at the vegetative stage present high 1-sucrose:sucrose fructosyltransferase (1-SST) in the distal region. The aim of the present study was to analyze how low temperature (5 degrees C) could affect fructan-metabolizing enzymes and fructan composition in the different regions of the rhizophores of intact and excised plants. 1-SST and 1-fructan:fructan fructosyltransferase (1-FFT) were higher in the distal region decreasing towards the proximal region in intact plants at the vegetative phase, and were drastically diminished when cold and/or excision were imposed. In contrast, 1-FEH increased in the proximal region of treated plants, mainly in excised plants subjected to cold. The ratio fructo-oligo to fructo-polysaccharides was significantly higher in plants exposed to low temperature (1.17 in intact plants and 1.64 in excised plants) than in plants exposed to natural temperature conditions (0.84 in intact vegetative plants and 0.58 in excised plants), suggesting that oligosaccharides are involved in the tolerance of plants to low temperature via 1-FEH, in addition to 1-FFT. Principal component analysis indicated different response mechanisms in fructan metabolism under defoliation and low temperature, which could be interpreted as part of the strategies to undergo unfavorable environmental conditions

  7. High ambient temperature increases 3,4-methylenedioxymethamphetamine (MDMA, "ecstasy")-induced Fos expression in a region-specific manner.

    PubMed

    Hargreaves, G A; Hunt, G E; Cornish, J L; McGregor, I S

    2007-03-16

    3,4-Methylenedioxymethamphetamine (MDMA, "Ecstasy") is a popular drug that is often taken under hot conditions at dance clubs. High ambient temperature increases MDMA-induced hyperthermia and recent studies suggest that high temperatures may also enhance the rewarding and prosocial effects of MDMA in rats. The present study investigated whether ambient temperature influences MDMA-induced expression of Fos, a marker of neural activation. Male Wistar rats received either MDMA (10 mg/kg i.p.) or saline, and were placed in test chambers for 2 h at either 19 or 30 degrees C. MDMA caused significant hyperthermia at 30 degrees C and a modest hypothermia at 19 degrees C. The 30 degrees C ambient temperature had little effect on Fos expression in vehicle-treated rats. However MDMA-induced Fos expression was augmented in 15 of 30 brain regions at the high temperature. These regions included (1) sites associated with thermoregulation such as the median preoptic nucleus, dorsomedial hypothalamus and raphe pallidus, (2) the supraoptic nucleus, a region important for osmoregulation and a key mediator of oxytocin and vasopressin release, (3) the medial and central nuclei of the amygdala, important in the regulation of social and emotional behaviors, and (4) the shell of the nucleus accumbens and (anterior) ventral tegmental area, regions associated with the reinforcing effects of MDMA. MDMA-induced Fos expression was unaffected by ambient temperature at many other sites, and was diminished at high temperature at one site (the islands of Calleja), suggesting that the effect of temperature on MDMA-induced Fos expression was not a general pharmacokinetic effect. Overall, these results indicate that high temperatures accentuate key neural effects of MDMA and this may help explain the widespread use of the drug under hot conditions at dance parties as well as the more hazardous nature of MDMA taken under such conditions.

  8. Direct and indirect ENSO modulation of winter temperature over the Asian–Pacific–American region

    PubMed Central

    Leung, Marco Y. T.; Zhou, Wen

    2016-01-01

    In this study, the direct and indirect atmospheric responses over the Asian–Pacific–American region to the El Niño–Southern Oscillation (ENSO) are documented. Since ENSO is likely to induce the northward displacement of the East Asian trough (NDEAT), some of the influence of ENSO on the Asian–Pacific–American region is possibly indirect and acts by inducing NDEAT. To separate corresponding influences of ENSO and NDEAT, partial regression is utilized. It is noted that temperature variations in the East Asian–Western Pacific region are controlled mainly by NDEAT. In contrast, ENSO demonstrates a weak direct relation to the temperature variation over the East Asian–Western Pacific region. This suggests that the influence of ENSO on this region is indirect, through modulation of NDEAT. On the other hand, temperature variation over the tropical eastern Pacific is dominated by ENSO forcing. Finally, temperature variation over the eastern North American–Western Pacific region is controlled by both ENSO and NDEAT. Nevertheless, their influences on temperature and circulation over this region tend to offset each other. This implies that temperature variation is controlled by their relative strengths. PMID:27821838

  9. Direct and indirect ENSO modulation of winter temperature over the Asian–Pacific–American region

    NASA Astrophysics Data System (ADS)

    Leung, Marco Y. T.; Zhou, Wen

    2016-11-01

    In this study, the direct and indirect atmospheric responses over the Asian–Pacific–American region to the El Niño–Southern Oscillation (ENSO) are documented. Since ENSO is likely to induce the northward displacement of the East Asian trough (NDEAT), some of the influence of ENSO on the Asian–Pacific–American region is possibly indirect and acts by inducing NDEAT. To separate corresponding influences of ENSO and NDEAT, partial regression is utilized. It is noted that temperature variations in the East Asian–Western Pacific region are controlled mainly by NDEAT. In contrast, ENSO demonstrates a weak direct relation to the temperature variation over the East Asian–Western Pacific region. This suggests that the influence of ENSO on this region is indirect, through modulation of NDEAT. On the other hand, temperature variation over the tropical eastern Pacific is dominated by ENSO forcing. Finally, temperature variation over the eastern North American–Western Pacific region is controlled by both ENSO and NDEAT. Nevertheless, their influences on temperature and circulation over this region tend to offset each other. This implies that temperature variation is controlled by their relative strengths.

  10. Regional Observation of Seismic Activity in Baekdu Mountain

    NASA Astrophysics Data System (ADS)

    Kim, Geunyoung; Che, Il-Young; Shin, Jin-Soo; Chi, Heon-Cheol

    2015-04-01

    Seismic unrest in Baekdu Mountain area between North Korea and Northeast China region has called attention to geological research community in Northeast Asia due to her historical and cultural importance. Seismic bulletin shows level of seismic activity in the area is higher than that of Jilin Province of Northeast China. Local volcanic observation shows a symptom of magmatic unrest in period between 2002 and 2006. Regional seismic data have been used to analyze seismic activity of the area. The seismic activity could be differentiated from other seismic phenomena in the region by the analysis.

  11. The Smad3 linker region contains a transcriptional activation domain.

    PubMed

    Wang, Guannan; Long, Jianyin; Matsuura, Isao; He, Dongming; Liu, Fang

    2005-02-15

    Transforming growth factor-beta (TGF-beta)/Smads regulate a wide variety of biological responses through transcriptional regulation of target genes. Smad3 plays a key role in TGF-beta/Smad-mediated transcriptional responses. Here, we show that the proline-rich linker region of Smad3 contains a transcriptional activation domain. When the linker region is fused to a heterologous DNA-binding domain, it activates transcription. We show that the linker region physically interacts with p300. The adenovirus E1a protein, which binds to p300, inhibits the transcriptional activity of the linker region, and overexpression of p300 can rescue the linker-mediated transcriptional activation. In contrast, an adenovirus E1a mutant, which cannot bind to p300, does not inhibit the linker-mediated transcription. The native Smad3 protein lacking the linker region is unable to mediate TGF-beta transcriptional activation responses, although it can be phosphorylated by the TGF-beta receptor at the C-terminal tail and has a significantly increased ability to form a heteromeric complex with Smad4. We show further that the linker region and the C-terminal domain of Smad3 synergize for transcriptional activation in the presence of TGF-beta. Thus our findings uncover an important function of the Smad3 linker region in Smad-mediated transcriptional control.

  12. Mass Divergence, Temperature and RH Anomalies in Regions of Enhanced Precipitation: Observations vs. GCMs

    NASA Astrophysics Data System (ADS)

    Mitovski, T.; Folkins, I.

    2008-12-01

    The purpose of our research is to compare diagnostics of modeled and observed vertical mass transport. The diagnostics are: dynamical (mass) divergence, temperature anomalies and RH anomaly regression in the regions of enhanced precipitation. The mass divergence provides an insight into the vertical mass transport. Here we are comparing the mass divergence estimated for 7 rings of stations for the rainy season to the same estimated from the third generation coupled global climate model (CGCM3-T63) and from the Geophysical Fluid Dynamics Laboratory Climate Model Version 2.1 (GFDL CM2.1) outputs. The second diagnostic comes from comparing observed to GCMs low level temperature anomalies. It is believed that the temperature anomalies are a result of mesoscale activity in the regions of enhanced precipitation [Folkins et al., 2007]. The low level cooling, a result of the stratiform heating mode [Mapes and Houze, 1995], is important for the excitation of small-scale gravity waves. The small-scale gravity waves contribute to the 'gregariousness' of deep convection by increasing the buoyancy of the neighbouring shallow cumuli [Mapes and Houze, 1993] and, consequently, the small-scale gravity waves create a positive feedback between existing deep convection and newborn shallow convective clouds. The last diagnostic is expressed through RH anomaly regression. The RH anomaly regressions are estimated for two days before and two days after maximum precipitation events from radiosondes and results are compared to regressions estimated from CGCM3 3-hourly output. Two distinct features are seen on the RH regression plot: growing cumuli clouds before the main event and a stratiform anvil after. In addition, there is also a 'pool' of dry mid-tropospheric air just after the maximum precipitation event which might be associated to mesoscale downdrafts.

  13. Evidence for Widespread Cooling in an Active Region Observed with the SDO Atmospheric Imaging Assembly

    NASA Technical Reports Server (NTRS)

    Viall, Nicholeen M.; Klimchuk, James A.

    2012-01-01

    A well known behavior of EUV light curves of discrete coronal loops is that the peak intensities of cooler channels or spectral lines are reached at progressively later times. This time lag is understood to be the result of hot coronal loop plasma cooling through these lower respective temperatures. However, loops typically comprise only a minority of the total emission in active regions. Is this cooling pattern a common property of active region coronal plasma, or does it only occur in unique circumstances, locations, and times? The new SDO/AIA data provide a wonderful opportunity to answer this question systematically for an entire active region. We measure the time lag between pairs of SDO/AIA EUV channels using 24 hours of images of AR 11082 observed on 19 June 2010. We find that there is a time-lag signal consistent with cooling plasma, just as is usually found for loops, throughout the active region including the diffuse emission between loops for the entire 24 hour duration. The pattern persists consistently for all channel pairs and choice of window length within the 24 hour time period, giving us confidence that the plasma is cooling from temperatures of greater than 3 MK, and sometimes exceeding 7 MK, down to temperatures lower than approx. 0.8 MK. This suggests that the bulk of the emitting coronal plasma in this active region is not steady; rather, it is dynamic and constantly evolving. These measurements provide crucial constraints on any model which seeks to describe coronal heating.

  14. A global view of F-region electron density and temperature at solar maximum

    NASA Technical Reports Server (NTRS)

    Brace, L. H.; Theis, R. F.; Hoegy, W. R.

    1982-01-01

    It is pointed out that the thermal structure of the ionosphere represents a quasi-static balance between a variety of heat sources and sinks which vary spatially and temporally on a wide range of time scales. The present investigation has the objective to present selected early results from the Dynamics Explorer-2 (DE-2) Langmuir probe instrument and to make an initial evaluation of how the thermal structure of the ionosphere at solar maximum differs from that observed at solar minimum. Bowen et al. (1964) and Brace and Reddy (1965) devised early empirical models of the F region electron temperature (Te), based on satellite Langmuir probe measurements at low levels of solar activity. The global structure of Te and the electron density (Ne) obtained in the current investigation is not very different from that reported by Brace and Reddy. The primary difference at solar maximum is that Ne is everywhere much higher, but Te differs only in detail.

  15. Activation energies and temperature effects from electrical spectra of soil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Apparent permittivity often has soil-specific temperature responses as well as soil water responses. These variations affect dielectric sensors, often requiring site-specific calibrations. Variations of permittivity as a function of frequency and temperature can be used to calculate activation energ...

  16. Ambient temperature and activation of implantable cardioverter defibrillators

    NASA Astrophysics Data System (ADS)

    McGuinn, L.; Hajat, S.; Wilkinson, P.; Armstrong, B.; Anderson, H. R.; Monk, V.; Harrison, R.

    2013-09-01

    The degree to which weather influences the occurrence of serious cardiac arrhythmias is not fully understood. To investigate, we studied the timing of activation of implanted cardiac defibrillators (ICDs) in relation to daily outdoor temperatures using a fixed stratum case-crossover approach. All patients attending ICD clinics in London between 1995 and 2003 were recruited onto the study. Temperature exposure for each ICD patient was determined by linking each patient's postcode of residence to their nearest temperature monitoring station in London and the South of England. There were 5,038 activations during the study period. Graphical inspection of ICD activation against temperature suggested increased risk at lower but not higher temperatures. For every 1 °C decrease in ambient temperature, risk of ventricular arrhythmias up to 7 days later increased by 1.2 % (95 % CI -0.6 %, 2.9 %). In threshold models, risk of ventricular arrhythmias increased by 11.2 % (0.5 %, 23.1 %) for every 1° decrease in temperature below 2 °C. Patients over the age of 65 exhibited the highest risk. This large study suggests an inverse relationship between ambient outdoor temperature and risk of ventricular arrhythmias. The highest risk was found for patients over the age of 65. This provides evidence about a mechanism for some cases of low-temperature cardiac death, and suggests a possible strategy for reducing risk among selected cardiac patients by encouraging behaviour modification to minimise cold exposure.

  17. Active structural vibration control: Robust to temperature variations

    NASA Astrophysics Data System (ADS)

    Gupta, Vivek; Sharma, Manu; Thakur, Nagesh

    2012-11-01

    d-form augmented piezoelectric constitutive equations which take into account temperature dependence of piezoelectric strain coefficient (d31) and permittivity (∈33), are converted into e-form. Using e-form constitutive equations, a finite element model of a smart two dimensional plate instrumented with piezoelectric patches is derived. Equations of motion are derived using Hamilton's variational principle. Coupled equations of motion are uncoupled using modal analysis. Modal state vectors are estimated using the Kalman observer. The first mode of smart cantilevered plate is actively controlled using negative first modal velocity feedback at various temperatures. Total control effort required to do so is calculated using the electro-mechanical impedance method. The temperature dependence of sensor voltage, control voltage, control effort and Kalman observer equations is shown analytically. Simulation results are presented using MATLAB. Variations in (i) peak sensor voltage, (ii) actual and estimated first modal velocities, (iii) peak control voltage, (iv) total control effort and (v) settling time with respect to temperature are presented. Active vibration control performance is not maintained at temperature away from reference temperature when the temperature dependence of piezoelectric stress coefficient ‘e31' and permittivity ‘∈33' is not included in piezoelectric constitutive equations. Active control of vibrations becomes robust to temperature variations when the temperature dependence of ‘e31' and ‘∈33' is included in piezoelectric constitutive equations.

  18. Calculating activation energies for temperature compensation in circadian rhythms

    NASA Astrophysics Data System (ADS)

    Bodenstein, C.; Heiland, I.; Schuster, S.

    2011-10-01

    Many biological species possess a circadian clock, which helps them anticipate daily variations in the environment. In the absence of external stimuli, the rhythm persists autonomously with a period of approximately 24 h. However, single pulses of light, nutrients, chemicals or temperature can shift the clock phase. In the case of light- and temperature-cycles, this allows entrainment of the clock to cycles of exactly 24 h. Circadian clocks have the remarkable property of temperature compensation, that is, the period of the circadian rhythm remains relatively constant within a physiological range of temperatures. For several organisms, temperature-regulated processes within the circadian clock have been identified in recent years. However, how these processes contribute to temperature compensation is not fully understood. Here, we theoretically investigate temperature compensation in general oscillatory systems. It is known that every oscillator can be locally temperature compensated around a reference temperature, if reactions are appropriately balanced. A balancing is always possible if the control coefficient with respect to the oscillation period of at least one reaction in the oscillator network is positive. However, for global temperature compensation, the whole physiological temperature range is relevant. Here, we use an approach which leads to an optimization problem subject to the local balancing principle. We use this approach to analyse different circadian clock models proposed in the literature and calculate activation energies that lead to temperature compensation.

  19. Temperature and the catalytic activity of enzymes: a fresh understanding.

    PubMed

    Daniel, Roy M; Danson, Michael J

    2013-09-02

    The discovery of an additional step in the progression of an enzyme from the active to inactive state under the influence of temperature has led to a better match with experimental data for all enzymes that follow Michaelis-Menten kinetics, and to an increased understanding of the process. The new model of the process, the Equilibrium Model, describes an additional mechanism by which temperature affects the activity of enzymes, with implications for ecological, metabolic, structural, and applied studies of enzymes.

  20. Prediction of Active-Region CME Productivity from Magnetograms

    NASA Technical Reports Server (NTRS)

    Falconer, D. A.; Moore, R. L.; Gary, G. A.

    2004-01-01

    We report results of an expanded evaluation of whole-active-region magnetic measures as predictors of active-region coronal mass ejection (CME) productivity. Previously, in a sample of 17 vector magnetograms of 12 bipolar active regions observed by the Marshall Space Flight Center (MSFC) vector magnetograph, from each magnetogram we extracted a measure of the size of the active region (the active region s total magnetic flux a) and four measures of the nonpotentiality of the active region: the strong-shear length L(sub SS), the strong-gradient length L(sub SG), the net vertical electric current I(sub N), and the net-current magnetic twist parameter alpha (sub IN). This sample size allowed us to show that each of the four nonpotentiality measures was statistically significantly correlated with active-region CME productivity in time windows of a few days centered on the day of the magnetogram. We have now added a fifth measure of active-region nonpotentiality (the best-constant-alpha magnetic twist parameter (alpha sub BC)), and have expanded the sample to 36 MSFC vector magnetograms of 31 bipolar active regions. This larger sample allows us to demonstrate statistically significant correlations of each of the five nonpotentiality measures with future CME productivity, in time windows of a few days starting from the day of the magnetogram. The two magnetic twist parameters (alpha (sub 1N) and alpha (sub BC)) are normalized measures of an active region s nonpotentially in that they do not depend directly on the size of the active region, while the other three nonpotentiality measures (L(sub SS), L(sub SG), and I(sub N)) are non-normalized measures in that they do depend directly on active-region size. We find (1) Each of the five nonpotentiality measures is statistically significantly correlated (correlation confidence level greater than 95%) with future CME productivity and has a CME prediction success rate of approximately 80%. (2) None of the nonpotentiality

  1. Observed Helicity of Active Regions in Solar Cycle 21

    NASA Technical Reports Server (NTRS)

    Hagyard, M. J.; Pevtsov, A. A.; Blehm, Z.; Smith, J. E.; Six, Frank (Technical Monitor)

    2003-01-01

    We report the results of a study of helicity in solar active regions during the peak of activity in solar cycle 21 from observations with the Marshall Space Flight Center's solar vector magnetograph. Using the force-free parameter alpha as the proxy for helicity, we calculated an average value of alpha for each of 60 active regions from a total of 449 vector magnetograms that were obtained during the period 1980 March to November. The signs of these average values of alpha were correlated with the latitude of the active regions to test the hemispheric rule of helicity that has been proposed for solar magnetic fields: negative helicity predominant in northern latitudes, positive in the southern ones. We have found that of the 60 regions that were observed, 30 obey the hemispheric rule and 30 do not.

  2. Photospheric Magnetic Free Energy Density of Solar Active Regions

    NASA Astrophysics Data System (ADS)

    Zhang, Hongqi

    2016-12-01

    We present the photospheric energy density of magnetic fields in two solar active regions (one of them recurrent) inferred from observational vector magnetograms, and compare it with other available differently defined energy parameters of magnetic fields in the photosphere. We analyze the magnetic fields in Active Regions NOAA 6580-6619-6659 and 11158. The quantity 1/4π{B}n\\cdot{B}p is an important energy parameter that reflects the contribution of magnetic shear to the difference between the potential (Bp) and the non-potential magnetic field (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 shows clear changes before the powerful solar flares in Active Region NOAA 11158, which is consistent with the change in magnetic fields in the flaring lower atmosphere.

  3. AFS dynamics in a short-lived active region

    NASA Astrophysics Data System (ADS)

    Zuccarello, F.; Battiato, V.; Contarino, L.; Romano, P.; Spadaro, D.; Vlahos, L.

    2005-11-01

    In the framework of the study on active region emergence, we report the results obtained from the analysis of the short-lived (7 days) active region NOAA 10407. The data used were acquired during an observational campaign carried out with the THEMIS telescope in IPM mode in July 2003, coordinated with other ground- and space-based instruments (INAF-OACT, DOT, BBSO, MDI/SOHO, EIT/SOHO, TRACE). We determined the morphological and magnetic evolution of NOAA 10407, as well as the velocity fields associated with its magnetic structures. Within the limits imposed by the spatial and temporal resolution of the images analyzed, the first evidence of the active region formation is initially observed in the transition region and lower corona, and later on (i.e. after about 7 h) in the inner layers, as found in a previous analysis concerning a long-lived, recurrent active region. The results also indicate that the AFS formed in the active region shows typical upward motion at the AFS's tops and downward motion at the footpoints. The velocity values relevant to the upward motions decrease over the evolution of the region, similarly to the case of the recurrent active region, while we notice an increasing trend in the downflow velocity during the early phases of the time interval analyzed by THEMIS. On the other hand, the AFS preceding legs show a higher downflow than the following ones, a result in contrast with that found in the long-lived active region. The chromospheric area overhanging the sunspot umbra shows an upward motion of ˜ 2 km s-1, while that above the pores shows a downward motion of ~4 km s-1.

  4. Extending temperature sum models to simulate onset of birch flowering on the regional scale

    NASA Astrophysics Data System (ADS)

    Klein, Christian; Biernath, Christian; Priesack, Eckart

    2015-04-01

    For human health issues a reliable forecast of the onset of flowering of different plants which produce allergenic pollen is important. Yet, there are numerous phenological models available with different degrees of model complexity. All models consider the effect of the air temperatures on plant development; but only few models also include other environmental factors and/or plant internal water and nutrient status. However, the more complex models often use empirical relations without physiological meaning and are often tested against small datasets derived from a limited amount of sites. Most models which are used to simulate plant phenology are based on the temporal integration of temperatures above a defined base temperature. A critical temperature sum then defines the onset of a new phenological stage. The use of models that base on temperatures only, is efficient as temperatures are the most frequently documented and available weather component on global, regional and local scales. These models score by their robustness over a wide range of environmental conditions. However, the simulations sometimes fail by more than 20 days compared to measurements, and thus are not adequate for their use in pollen forecast. We tested the ability of temperature sum models to simulate onset of flowering of wild (e.g. birch) and domestic plants in Bavaria. In a first step we therefore determined both, a regional averaged optimum base temperature and temperature sum for the examined plant species in Bavaria. In the second step, the base temperatures were optimized to each site for the simulation period 2001-2010. Our hypothesis is that domestic plants depend much less on the regional weather conditions than wild plants do, due to low and high genetic variability, respectively. If so, the observed base temperatures of wild plants are smaller for low annual average temperatures and higher for high annual average temperatures. In the cases of domestic plants the optimized base

  5. Coronal temperatures of selected active cool stars as derived from low resolution Einstein observations

    NASA Technical Reports Server (NTRS)

    Vilhu, Osmi; Linsky, Jeffrey L.

    1990-01-01

    Mean coronal temperatures of some active G-K stars were derived from Rev1-processed Einstein-observatory's IPC-spectra. The combined X-ray and transition region emission line data are in rough agreement with static coronal loop models. Although the sample is too small to derive any statistically significant conclusions, it suggests that the mean coronal temperature depends linearly on the inverse Rossby-number, with saturation at short rotation periods.

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

    PubMed Central

    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 < 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. PMID:27375903

  7. DISTRIBUTION OF ELECTRIC CURRENTS IN SOLAR ACTIVE REGIONS

    SciTech Connect

    Török, T.; Titov, V. S.; Mikić, Z.; Leake, J. E.; Archontis, V.; Linton, M. G.; Dalmasse, K.; Aulanier, G.; Kliem, B.

    2014-02-10

    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.

  8. Photospheric Magnetic Diffusion by Measuring Moments of Active Regions

    NASA Astrophysics Data System (ADS)

    Engell, Alexander; Longcope, D.

    2013-07-01

    Photospheric magnetic surface diffusion is an important constraint for the solar dynamo. The HMI Active Region Patches (HARPs) program automatically identify all magnetic regions above a certain flux. In our study we measure the moments of ARs that are no longer actively emerging and can thereby give us good statistical constraints on photospheric diffusion. We also present the diffusion properties as a function of latitude, flux density, and single polarity (leading or following) within each HARP.

  9. Solar Irradiance Variations on Active Region Time Scales

    NASA Technical Reports Server (NTRS)

    Labonte, B. J. (Editor); Chapman, G. A. (Editor); Hudson, H. S. (Editor); Willson, R. C. (Editor)

    1984-01-01

    The variations of the total solar irradiance is an important tool for studying the Sun, thanks to the development of very precise sensors such as the ACRIM instrument on board the Solar Maximum Mission. The largest variations of the total irradiance occur on time scales of a few days are caused by solar active regions, especially sunspots. Efforts were made to describe the active region effects on total and spectral irradiance.

  10. New method of estimating temperatures near the mesopause region using meteor radar observations

    NASA Astrophysics Data System (ADS)

    Lee, Changsup; Kim, Jeong-Han; Jee, Geonhwa; Lee, Wonseok; Song, In-Sun; Kim, Yong Ha

    2016-10-01

    We present a novel method of estimating temperatures near the mesopause region using meteor radar observations. The method utilizes the linear relationship between the full width at half maximum (FWHM) of the meteor height distribution and the temperature at the meteor peak height. Once the proportionality constant of the linear relationship is determined from independent temperature measurements performed over a specific period of time by the Microwave Limb Sounder (MLS) instrument on board the Aura satellite, the temperature can be estimated continuously according to the measurements of the FWHM alone without additional information. The temperatures estimated from the FWHM are consistent with the MLS temperatures throughout the study period within a margin of 3.0%. Although previous methods are based on temperature gradient or pressure assumptions, the new method does not require such assumptions, which allows us to estimate the temperature at approximately 90 km with better precision.

  11. Regionality of record-breaking low temperature events in China and its associated circulation

    NASA Astrophysics Data System (ADS)

    Kuang, Xueyuan; Zhang, Yaocun; Huang, Danqing; Huang, Ying

    2016-03-01

    Extreme cold events frequently occur around the world in recent several years and arouse widespread concern. In this study, 17 record-breaking event processes (RBEPs) of low temperature during 1981-2012 are identified by using daily minimum temperature at 1897 meteorological stations in China. These RBEPs are classified into two types based on the occurring area at northern or southern China to compositely examine the associated circulations. Although the correspondence between Arctic oscillation (AO) and RBEPs is not linearly stable, there still exist relationship between them, i.e. under AO negative phase the RBEPs tend to occur at northern China, nor the southern part, where the RBEPs prefer to happen under AO positive phase. In the RBEPs occurring at southern China, the continent high pressure over Mongolia area is extremely intensified and the East Asian polar front jet stream is enhanced accompanied with strong synoptic-scale eddy kinetic energy transports. Correspondingly, the cold air masses break out and unobstructed southward intrude to low latitudes, causing severe cooling effect in southern China. In the RBEPs occurring at northern China, however, the extremely intensified high pressure over northern Siberian area, combining with the northward enhanced subtropical jet stream, lead to the cold air mass accumulation and blockage at mid-latitudes and therefore RBEPs of low temperature at this area. Further study implies that interdecadal change of the AO phase and differences of synoptic-scale eddy activity might synthetically attribute to the different regional preference of those RBEPs of low temperature that are mostly located at southern China in 1990s but concentrated in northern China in 2000s.

  12. Static and Impulsive Models of Solar Active Regions

    NASA Technical Reports Server (NTRS)

    Patsourakos, S.; Klimchuk, James A.

    2008-01-01

    The physical modeling of active regions (ARs) and of the global coronal is receiving increasing interest lately. Recent attempts to model ARs using static equilibrium models were quite successful in reproducing AR images of hot soft X-ray (SXR) loops. They however failed to predict the bright EUV warm loops permeating ARs: the synthetic images were dominated by intense footpoint emission. We demonstrate that this failure is due to the very weak dependence of loop temperature on loop length which cannot simultaneously account for both hot and warm loops in the same AR. We then consider time-dependent AR models based on nanoflare heating. We demonstrate that such models can simultaneously reproduce EUV and SXR loops in ARs. Moreover, they predict radial intensity variations consistent with the localized core and extended emissions in SXR and EUV AR observations respectively. We finally show how the AR morphology can be used as a gauge of the properties (duration, energy, spatial dependence, repetition time) of the impulsive heating.

  13. Active region emission measure distributions and implications for nanoflare heating

    SciTech Connect

    Cargill, P. J.

    2014-03-20

    The temperature dependence of the emission measure (EM) in the core of active regions coronal loops is an important diagnostic of heating processes. Observations indicate that EM(T) ∼ T{sup a} below approximately 4 MK, with 2 < a < 5. Zero-dimensional hydrodynamic simulations of nanoflare trains are used to demonstrate the dependence of a on the time between individual nanoflares (T{sub N} ) and the distribution of nanoflare energies. If T{sub N} is greater than a few thousand seconds, a < 3. For smaller values, trains of equally spaced nanoflares cannot account for the observed range of a if the distribution of nanoflare energies is either constant, randomly distributed, or a power law. Power law distributions where there is a delay between consecutive nanoflares proportional to the energy of the second nanoflare do lead to the observed range of a. However, T{sub N} must then be of the order of hundreds to no more than a few thousand seconds. If a nanoflare leads to the relaxation of a stressed coronal field to a near-potential state, the time taken to build up the required magnetic energy is thus too long to account for the EM measurements. Instead, it is suggested that a nanoflare involves the relaxation from one stressed coronal state to another, dissipating only a small fraction of the available magnetic energy. A consequence is that nanoflare energies may be smaller than previously envisioned.

  14. Active Region Emission Measure Distributions and Implications for Nanoflare Heating

    NASA Astrophysics Data System (ADS)

    Cargill, P. J.

    2014-03-01

    The temperature dependence of the emission measure (EM) in the core of active regions coronal loops is an important diagnostic of heating processes. Observations indicate that EM(T) ~ Ta below approximately 4 MK, with 2 < a < 5. Zero-dimensional hydrodynamic simulations of nanoflare trains are used to demonstrate the dependence of a on the time between individual nanoflares (TN ) and the distribution of nanoflare energies. If TN is greater than a few thousand seconds, a < 3. For smaller values, trains of equally spaced nanoflares cannot account for the observed range of a if the distribution of nanoflare energies is either constant, randomly distributed, or a power law. Power law distributions where there is a delay between consecutive nanoflares proportional to the energy of the second nanoflare do lead to the observed range of a. However, TN must then be of the order of hundreds to no more than a few thousand seconds. If a nanoflare leads to the relaxation of a stressed coronal field to a near-potential state, the time taken to build up the required magnetic energy is thus too long to account for the EM measurements. Instead, it is suggested that a nanoflare involves the relaxation from one stressed coronal state to another, dissipating only a small fraction of the available magnetic energy. A consequence is that nanoflare energies may be smaller than previously envisioned.

  15. The nature of chromospheric active regions on V410 Tauri

    NASA Astrophysics Data System (ADS)

    Mekkaden, M. V.; Pukalenthi, S.; Muneer, S.; Bastian, Anju Barbara

    2005-12-01

    We present spectroscopic observations in the region of H alpha and Li I lines of the weak emission T Tauri star V410 Tau obtained over 1999/2000, 2002/2003 and 2003/2004 seasons. The emission strength showed rotational modulation during the 1999/2000 season in such a way that the emis- sion strength is maximum at light minimum and vice versa. This indicates that the photospheric and chromospheric active regions overlap over shorter dura- tions of time and the lifetimes of chromospheric active regions are far shorter than the photospheric active regions. But the observations obtained during the 2003/2004 season do not follow the trend observed at earlier seasons. This can be due to the change in the location of chromospheric active regions. Another possibility is the occurrence of a major change in the photospheric active re- gions that have caused a redistribution of photospheric as well as chromospheric active regions. The Li I EW does not show any appreciable change over the four-year period.

  16. Active Region Moss: Doppler Shifts from Hinode/Extreme-ultraviolet Imaging Spectrometer Observations

    NASA Astrophysics Data System (ADS)

    Tripathi, Durgesh; Mason, Helen E.; Klimchuk, James A.

    2012-07-01

    Studying the Doppler shifts and the temperature dependence of Doppler shifts in moss regions can help us understand the heating processes in the core of the active regions. In this paper, we have used an active region observation recorded by the Extreme-ultraviolet Imaging Spectrometer (EIS) on board Hinode on 2007 December 12 to measure the Doppler shifts in the moss regions. We have distinguished the moss regions from the rest of the active region by defining a low-density cutoff as derived by Tripathi et al. in 2010. We have carried out a very careful analysis of the EIS wavelength calibration based on the method described by Young et al. in 2012. For spectral lines having maximum sensitivity between log T = 5.85 and log T = 6.25 K, we find that the velocity distribution peaks at around 0 km s-1 with an estimated error of 4-5 km s-1. The width of the distribution decreases with temperature. The mean of the distribution shows a blueshift which increases with increasing temperature and the distribution also shows asymmetries toward blueshift. Comparing these results with observables predicted from different coronal heating models, we find that these results are consistent with both steady and impulsive heating scenarios. However, the fact that there are a significant number of pixels showing velocity amplitudes that exceed the uncertainty of 5 km s-1 is suggestive of impulsive heating. Clearly, further observational constraints are needed to distinguish between these two heating scenarios.

  17. Twist of Magnetic Fields in Solar Active Regions

    NASA Astrophysics Data System (ADS)

    Zhang, Hongqi; Bao, Shudong; Kuzanyan, Kirill M.

    2002-05-01

    We study the twist properties of photospheric magnetic fields in solar active regions using magnetographic data on 422 active regions obtained at the Huairou Solar Observing Station in 1988 1997. We calculate the mean twist (force-free field αf) of the active regions and compare it with the mean current-helicity density of these same active regions, h c =B ∥·(∇×B)∥. The latitude and longitude distributions and time dependence of these quantities is analyzed. These parameters represent two different tracers of the α effect in dynamo theory, so we might expect them to possess similar properties. However, apart from differences in their definitions, they also display differences associated with the technique used to recalculate the magnetographic data and with their different physical meanings. The distributions of the mean αf and h c both show hemispherical asymmetry—negative (positive) values in the northern (southern) hemisphere—although this tendency is stronger for h c. One reason for these differences may be the averaging procedure, when twists of opposite sign in regions with weak fields make a small contribution to the mean current-helicity density. Such transequatorial regularity is in agreement with the expectations of dynamo theory. In some active regions, the average αf and h c do not obey this transequatorial rule. As a whole, the mean twist of the magnetic fields αf of active regions does not vary significantly with the solar cycle. Active regions that do not follow the general behavior for αf do not show any appreciable tendency to cluster at certain longitudes, in contrast to results for h c noted in previous studies. We analyze similarities and differences in the distributions of these two quantities. We conclude that using only one of these tracers, such as αf, to search for signatures of the α effect can have disadvantages, which should be taken into account in future studies.

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

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

    Context. 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. Aims: Our goal is to collate a uniform data set of emerging active regions observed by the SDO/HMI instrument suitable for helioseismic analysis, where each active region is centred on a 60° × 60° area and can be observed up to seven days before emergence. Methods: 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). The control regions do not have any strong emerging flux within 10° of the centre of the map. Each region was tracked at the Carrington rotation rate as it crossed the solar disk, within approximately 65° from the central meridian and up to seven days before, and seven days after, emergence. The mapped and tracked data, consisting of line-of-sight velocity, line-of-sight magnetic field, and intensity as observed by SDO/HMI, are stored in datacubes that are 410 min in duration and spaced 320 min apart. 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. Results: 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 leading and trailing polarities from the line-of-sight magnetogram maps during the first day after emergence. The latitudinally averaged line-of-sight magnetic field of all the EARs shows that, on average, the leading (trailing) polarity moves in a prograde (retrograde) direction with a speed of 121 ± 22 m s-1 (-70 ± 13 m s-1) relative to the

  19. Earth resources-regional transfer activity contracts review

    NASA Technical Reports Server (NTRS)

    Bensko, J., Jr.; Daniels, J. L.; Downs, S. W., Jr.; Jones, N. L.; Morton, R. R.; Paludan, C. T.

    1977-01-01

    A regional transfer activity contracts review held by the Earth Resources Office was summarized. Contracts in the earth resources field primarily directed toward applications of satellite data and technology in solution of state and regional problems were reviewed. A summary of the progress of each contract was given in order to share experiences of researchers across a seven state region. The region included Missouri, Kentucky, Tennessee, Mississippi, Alabama, Georgia, and North Carolina. Research in several earth science disciplines included forestry, limnology, water resources, land use, geology, and mathematical modeling. The use of computers for establishment of information retrieval systems was also emphasized.

  20. Middle Atmosphere Temperature and Dynamics as Revealed from D-region Observations

    NASA Technical Reports Server (NTRS)

    Danilov, A. D.

    1984-01-01

    The concept of so-called meteorological control of the ionospheric D-region is presently undergoing development. According to this concept the electron concentration in this region is governed not only by solar and geomagnetic parameters but strongly depends on the temperature and dynamical regime of the mesosphere and stratosphere. How this connection between D-region and meteorological parameters can be used to obtain some information about middle atmosphere temperature and dynamics is examined. The essential points of the meteorological control concept are reviewed and the influence of turbulence on nitric oxide distribution and thus the ion production rate is discussed.

  1. Predictions of active region flaring probability using subsurface helicity measurements

    NASA Astrophysics Data System (ADS)

    Reinard, A. A.; Komm, R.; Hill, F.

    2010-12-01

    Solar flares are responsible for a number of hazardous effects on the earth such as disabling high-frequency radio communications, interfering with GPS measurements, and disrupting satellites. However, forecasting flare occurrence is currently very difficult. One possible means for predicting flare occurrence lies in helioseismology, i.e. analysis of the region below the active region for signs of an impending flare. Time series helioseismic data collected by the Global Oscillation Network Group (GONG) has been analyzed for a subset of active regions that produce large flares and a subset with very high magnetic field strength that produce no flares. A predictive parameter has been developed and analyzed using discriminant analysis as well as traditional forecasting tools such as the Heidke skill score. Preliminary results show that this parameter predicts the flaring probability of an active region 2-3 days in advance with a relatively high degree of success.

  2. Natural and forced air temperature variability in the Labrador region of Canada during the past century

    NASA Astrophysics Data System (ADS)

    Way, Robert G.; Viau, Andre E.

    2015-08-01

    Evaluation of Labrador air temperatures over the past century (1881-2011) shows multi-scale climate variability and strong linkages with ocean-atmospheric modes of variability and external forcings. The Arctic Oscillation, Atlantic Multidecadal Oscillation, and El Nino Southern Oscillation are shown to be the dominant seasonal and interannual drivers of regional air temperature variability for most of the past century. Several global climate models show disagreement with observations on the rate of recent warming which suggests that models are currently unable to reproduce regional climate variability in Labrador air temperature. Using a combination of empirical statistical modeling and global climate models, we show that 33 % of the variability in annual Labrador air temperatures over the period 1881-2011 can be explained by natural factors alone; however, the inclusion of anthropogenic forcing increases the explained variance to 65 %. Rapid warming over the past 17 years is shown to be linked to both natural and anthropogenic factors with several anomalously warm years being primarily linked to recent anomalies in the Arctic Oscillation and North Atlantic sea surface temperatures. Evidence is also presented that both empirical statistical models and global climate models underestimate the regional air temperature response to ocean salinity anomalies and volcanic eruptions. These results provide important insight into the predictability of future regional climate impacts for the Labrador region.

  3. Tracing temperature in a nanometer size region in a picosecond time period

    PubMed Central

    Nakajima, Kaoru; Kitayama, Takumi; Hayashi, Hiroaki; Matsuda, Makoto; Sataka, Masao; Tsujimoto, Masahiko; Toulemonde, Marcel; Bouffard, Serge; Kimura, Kenji

    2015-01-01

    Irradiation of materials with either swift heavy ions or slow highly charged ions leads to ultrafast heating on a timescale of several picosecond in a region of several nanometer. This ultrafast local heating result in formation of nanostructures, which provide a number of potential applications in nanotechnologies. These nanostructures are believed to be formed when the local temperature rises beyond the melting or boiling point of the material. Conventional techniques, however, are not applicable to measure temperature in such a localized region in a short time period. Here, we propose a novel method for tracing temperature in a nanometer region in a picosecond time period by utilizing desorption of gold nanoparticles around the ion impact position. The feasibility is examined by comparing with the temperature evolution predicted by a theoretical model. PMID:26293488

  4. Tracing temperature in a nanometer size region in a picosecond time period.

    PubMed

    Nakajima, Kaoru; Kitayama, Takumi; Hayashi, Hiroaki; Matsuda, Makoto; Sataka, Masao; Tsujimoto, Masahiko; Toulemonde, Marcel; Bouffard, Serge; Kimura, Kenji

    2015-08-21

    Irradiation of materials with either swift heavy ions or slow highly charged ions leads to ultrafast heating on a timescale of several picosecond in a region of several nanometer. This ultrafast local heating result in formation of nanostructures, which provide a number of potential applications in nanotechnologies. These nanostructures are believed to be formed when the local temperature rises beyond the melting or boiling point of the material. Conventional techniques, however, are not applicable to measure temperature in such a localized region in a short time period. Here, we propose a novel method for tracing temperature in a nanometer region in a picosecond time period by utilizing desorption of gold nanoparticles around the ion impact position. The feasibility is examined by comparing with the temperature evolution predicted by a theoretical model.

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

    ERIC Educational Resources Information Center

    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.…

  6. IFLA General Conference, 1985. Division on Regional Activities. Papers.

    ERIC Educational Resources Information Center

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

    Papers on regional library activities which were presented at the 1985 International Federation of Library Associations (IFLA) conference include: (1) "Importance of Information Resources in National Development with Particular Reference to the Asian Scene" (Yogendra P. Dubey, India); (2) "Report of the Activities of the Regional…

  7. Fresnel-region fields and antenna noise-temperature calculations for advanced microwave sounding units

    NASA Technical Reports Server (NTRS)

    Schmidt, R. F.

    1982-01-01

    A transition from the antenna noise temperature formulation for extended noise sources in the far-field or Fraunhofer-region of an antenna to one of the intermediate near field or Fresnel-region is discussed. The effort is directed toward microwave antenna simulations and high-speed digital computer analysis of radiometric sounding units used to obtain water vapor and temperature profiles of the atmosphere. Fresnel-region fields are compared at various distances from the aperture. The antenna noise temperature contribution of an annular noise source is computed in the Fresnel-region (D squared/16 lambda) for a 13.2 cm diameter offset-paraboloid aperture at 60 GHz. The time-average Poynting vector is used to effect the computation.

  8. Validation of climate model-inferred regional temperature change for late-glacial Europe

    PubMed Central

    Heiri, Oliver; Brooks, Stephen J.; Renssen, Hans; Bedford, Alan; Hazekamp, Marjolein; Ilyashuk, Boris; Jeffers, Elizabeth S.; Lang, Barbara; Kirilova, Emiliya; Kuiper, Saskia; Millet, Laurent; Samartin, Stéphanie; Toth, Monika; Verbruggen, Frederike; Watson, Jenny E.; van Asch, Nelleke; Lammertsma, Emmy; Amon, Leeli; Birks, Hilary H.; Birks, H. John B.; Mortensen, Morten F.; Hoek, Wim Z.; Magyari, Enikö; Sobrino, Castor Muñoz; Seppä, Heikki; Tinner, Willy; Tonkov, Spassimir; Veski, Siim; Lotter, André F.

    2014-01-01

    Comparisons of climate model hindcasts with independent proxy data are essential for assessing model performance in non-analogue situations. However, standardized paleoclimate datasets for assessing the spatial pattern of past climatic change across continents are lacking for some of the most dynamic episodes of Earth's recent past. Here we present a new chironomid-based paleotemperature dataset designed to assess climate model hindcasts of regional summer temperature change in Europe during the late-glacial and early Holocene. Latitudinal and longitudinal patterns of inferred temperature change are in excellent agreement with simulations by the ECHAM-4 model, implying that atmospheric general circulation models like ECHAM-4 can successfully predict regionally diverging temperature trends in Europe, even when conditions differ significantly from present. However, ECHAM-4 infers larger amplitudes of change and higher temperatures during warm phases than our paleotemperature estimates, suggesting that this and similar models may overestimate past and potentially also future summer temperature changes in Europe. PMID:25208610

  9. Validation of climate model-inferred regional temperature change for late-glacial Europe.

    PubMed

    Heiri, Oliver; Brooks, Stephen J; Renssen, Hans; Bedford, Alan; Hazekamp, Marjolein; Ilyashuk, Boris; Jeffers, Elizabeth S; Lang, Barbara; Kirilova, Emiliya; Kuiper, Saskia; Millet, Laurent; Samartin, Stéphanie; Toth, Monika; Verbruggen, Frederike; Watson, Jenny E; van Asch, Nelleke; Lammertsma, Emmy; Amon, Leeli; Birks, Hilary H; Birks, H John B; Mortensen, Morten F; Hoek, Wim Z; Magyari, Enikö; Muñoz Sobrino, Castor; Seppä, Heikki; Tinner, Willy; Tonkov, Spassimir; Veski, Siim; Lotter, André F

    2014-09-11

    Comparisons of climate model hindcasts with independent proxy data are essential for assessing model performance in non-analogue situations. However, standardized palaeoclimate data sets for assessing the spatial pattern of past climatic change across continents are lacking for some of the most dynamic episodes of Earth's recent past. Here we present a new chironomid-based palaeotemperature dataset designed to assess climate model hindcasts of regional summer temperature change in Europe during the late-glacial and early Holocene. Latitudinal and longitudinal patterns of inferred temperature change are in excellent agreement with simulations by the ECHAM-4 model, implying that atmospheric general circulation models like ECHAM-4 can successfully predict regionally diverging temperature trends in Europe, even when conditions differ significantly from present. However, ECHAM-4 infers larger amplitudes of change and higher temperatures during warm phases than our palaeotemperature estimates, suggesting that this and similar models may overestimate past and potentially also future summer temperature changes in Europe.

  10. A new soil-temperature module for SWAT application in regions with seasonal snow cover

    NASA Astrophysics Data System (ADS)

    Qi, Junyu; Li, Sheng; Li, Qiang; Xing, Zisheng; Bourque, Charles P.-A.; Meng, Fan-Rui

    2016-07-01

    Accurate estimates of soil temperature are important for quantifying hydrological and biological processes in hydrological models. Soil temperature predictions in the widely used Soil and Water Assessment Tool (SWAT) have large prediction errors when applied to regions with significant snow cover during winter. In this study, a new physically-based soil-temperature module is developed as an alternative to the empirical soil-temperature module currently used in SWAT. The physically-based module ​simulates soil temperature in different soil layers as a result of energy transfer between the atmosphere and soil (or snow) interface. The modified version of SWAT with the new soil-temperature module in place, introduces only three new parameters over the original soil-temperature module. Both the original and new soil-temperature modules are tested against field data from the Black Brook Watershed, a small watershed in Atlantic Canada. The results indicate that both versions of soil-temperature module ​are able to provide acceptable predictions of temperature in different layers of the soil during non-winter seasons. However, the original module severely underestimates soil temperatures in winter (within -10 to -20 °C), while the new module produces results that are more consistent with field measurements (within -2 to 2 °C). In addition, unlike its counterpart, the new module ​is able to simulate freeze-thaw cycles in the soil profile. Ice-water content variations in winter are reasonably simulated by the new module for different snow cover scenarios. In general, modified-SWAT improves prediction accuracy on baseflow discharge compared with the original-SWAT, due to improved estimates of soil temperature during winter. The new physically-based soil-temperature module has greatly improved the ability of SWAT to predict soil temperatures under seasonal snow cover, which is essential to the application of the model in regions like Atlantic Canada.

  11. Activated region fitting: a robust high-power method for fMRI analysis using parameterized regions of activation.

    PubMed

    Weeda, Wouter D; Waldorp, Lourens J; Christoffels, Ingrid; Huizenga, Hilde M

    2009-08-01

    An important issue in the analysis of fMRI is how to account for the spatial smoothness of activated regions. In this article a method is proposed to accomplish this by modeling activated regions with Gaussian shapes. Hypothesis tests on the location, spatial extent, and amplitude of these regions are performed instead of hypothesis tests of individual voxels. This increases power and eases interpretation. Simulation studies show robust hypothesis tests under misspecification of the shape model, and increased power over standard techniques especially at low signal-to-noise ratios. An application to real single-subject data also indicates that the method has increased power over standard methods.

  12. Regionalized temperature variations in the upper 400 km of the Earth's mantle

    NASA Astrophysics Data System (ADS)

    Tralli, David M.; Ita, Joel J.

    Tectonically regionalized variations in the temperature of the upper 400 km of the Earth's mantle are estimated from analysis of global seismic travel-time data cataloged by the International Seismological Centre (ISC). Seismic parameter profiles are determined from estimates of P and S velocities obtained by tau inversion. Summary phase diagrams for the olivine and pyroxene-garnet subsystems are constructed in conjunction with a thermodynamic potential formulation that allows self-consistent determination of density, bulk modulus and adiabats throughout the pressure and temperature regimes of the mantle. Perturbations in estimated seismic parameters are expressed in terms of variations in temperature using the model temperature derivatives of the bulk modulus and density at a given temperature and pressure. Confidence bounds on the velocity estimates are used to place corresponding bounds on the constructed seismic parameters. A simple differential relationship is solved iteratively to obtain a temperature variation for a given variation in seismic parameter. This approach allows the estimation of a range of seismically determined temperature variations by employing a given compositional model. Results indicate that whereas the P and S velocity variations in the upper mantle are consistent with the tectonic regionalization, variations in V p/V s ratios are irregular. This leads to unstable estimates of the seismic parameters and thus estimates of mean temperature anomalies, typically within 600°C of the weighted mean, that are inconsistent with the regionalized seismic data. A comparison of two compositional models is used to show the trade-off with estimated temperature variations. A refined regionalization and analysis of a larger ISC data set are suggested to stabilize the S velocity inversion, reduce statistical uncertainties on the seismic parameters, and thus improve constraints on estimated temperature variations.

  13. Solar activity influence on air temperature regimes in caves

    NASA Astrophysics Data System (ADS)

    Stoeva, Penka; Mikhalev, Alexander; Stoev, Alexey

    Cave atmospheres are generally included in the processes that happen in the external atmosphere as circulation of the cave air is connected with the most general circulation of the air in the earth’s atmosphere. Such isolated volumes as the air of caves are also influenced by the variations of solar activity. We discuss cave air temperature response to climate and solar and geomagnetic activity for four show caves in Bulgaria studied for a period of 46 years (1968 - 2013). Everyday noon measurements in Ledenika, Saeva dupka, Snezhanka and Uhlovitsa cave have been used. Temperatures of the air in the zone of constant temperatures (ZCT) are compared with surface temperatures recorded at meteorological stations situated near about the caves - in the towns of Vratsa, Lovech, Peshtera and Smolyan, respectively. For comparison, The Hansen cave, Middle cave and Timpanogos cave from the Timpanogos Cave National Monument, Utah, USA situated nearly at the same latitude have also been examined. Our study shows that the correlation between cave air temperature time series and sunspot number is better than that between the cave air temperature and Apmax indices; that t°ZCT is rather connected with the first peak in geomagnetic activity, which is associated with transient solar activity (CMEs) than with the second one, which is higher and connected with the recurrent high speed streams from coronal holes. Air temperatures of all examined show caves, except the Ledenika cave, which is ice cave show decreasing trends. On the contrary, measurements at the meteorological stations show increasing trends in the surface air temperatures. The trend is decreasing for the Timpanogos cave system, USA. The conclusion is that surface temperature trends depend on the climatic zone, in which the cave is situated, and there is no apparent relation between temperatures inside and outside the caves. We consider possible mechanism of solar cosmic rays influence on the air temperatures in caves

  14. Relationship between skin temperature and muscle activation during incremental cycle exercise.

    PubMed

    Priego Quesada, Jose I; Carpes, Felipe P; Bini, Rodrigo R; Salvador Palmer, Rosario; Pérez-Soriano, Pedro; Cibrián Ortiz de Anda, Rosa M

    2015-02-01

    While different studies showed that better fitness level adds to the efficiency of the thermoregulatory system, the relationship between muscular effort and skin temperature is still unknown. Therefore, the present study assessed the relationship between neuromuscular activation and skin temperature during cycle exercise. Ten physically active participants performed an incremental workload cycling test to exhaustion while neuromuscular activations were recorded (via surface electromyography - EMG) from rectus femoris, vastus lateralis, biceps femoris and gastrocnemius medialis. Thermographic images were recorded before, immediately after and 10 min after finishing the cycling test, at four body regions of interest corresponding to the muscles where neuromuscular activations were monitored. Frequency band analysis was conducted to assess spectral properties of EMG signals in order to infer on priority in recruitment of motor units. Significant inverse relationship between changes in skin temperature and changes in overall neuromuscular activation for vastus lateralis was observed (r<-0.5 and p<0.04). Significant positive relationship was observed between skin temperature and low frequency components of neuromuscular activation from vastus lateralis (r>0.7 and p<0.01). Participants with larger overall activation and reduced low frequency component for vastus lateralis activation presented a better adaptive response of their thermoregulatory system by showing fewer changes in skin temperature after incremental cycling test.

  15. Minimum extreme temperature in the gulf of mexico: is there a connection with solar activity?

    NASA Astrophysics Data System (ADS)

    Maravilla, D.; Mendoza, B.; Jauregui, E.

    Minimum extreme temperature ( MET) series from several meteorological stations of the Gulf of Mexico are spectrally analyzed using the Maximum Entrophy Method. We obtained periodicities similar to those found in the sunspot number, the magnetic solar cycle, comic ray fluxes and geomagnetic activity which are modulated by solar activity. We suggested that the solar signal is perhaps present in the MET record of this region of Mexico.

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

    NASA Technical Reports Server (NTRS)

    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. An assessment of precipitation and surface air temperature over China by regional climate models

    NASA Astrophysics Data System (ADS)

    Wang, Xueyuan; Tang, Jianping; Niu, Xiaorui; Wang, Shuyu

    2016-12-01

    An analysis of a 20-year summer time simulation of present-day climate (1989-2008) over China using four regional climate models coupled with different land surface models is carried out. The climatic means, interannual variability, linear trends, and extremes are examined, with focus on precipitation and near surface air temperature. The models are able to reproduce the basic features of the observed summer mean precipitation and temperature over China and the regional detail due to topographic forcing. Overall, the model performance is better for temperature than that of precipitation. The models reasonably grasp the major anomalies and standard deviations over China and the five subregions studied. The models generally reproduce the spatial pattern of high interannual variability over wet regions, and low variability over the dry regions. The models also capture well the variable temperature gradient increase to the north by latitude. Both the observed and simulated linear trend of precipitation shows a drying tendency over the Yangtze River Basin and wetting over South China. The models capture well the relatively small temperature trends in large areas of China. The models reasonably simulate the characteristics of extreme precipitation indices of heavy rain days and heavy precipitation fraction. Most of the models also performed well in capturing both the sign and magnitude of the daily maximum and minimum temperatures over China.

  18. Interplanetary planar magnetic structures associated with expanding active regions

    NASA Technical Reports Server (NTRS)

    Nakagawa, Tomoko; Uchida, Yutaka

    1995-01-01

    Planar magnetic structures are interplanetary objects whose magnetic field cannot be explained by Parker's solar wind model. They are characterized by two-dimensional structure of magnetic field that are highly variable and parallel to a plane which is inclined to the ecliptic plane. They appeared independently of interplanetary compression, solar flares, active prominences nor filament disappearances, but the sources often coincided with active regions. On the other hand, it has been discovered by the Yohkoh Soft X-ray telescope that active-region corona expand outwards at speeds of a few to a few tens of km/s near the Sun. The expansions occurred repeatedly, almost continually, even in the absence of any sizable flares. In the Yohkoh Soft X-ray images, the active-region corona seems to expand out into interplanetary space. Solar sources of interplanetary planar magnetic structures observed by Sakigake were examined by Yohkoh soft X-ray telescope. During a quiet period of the Sun from January 6 to November 11, 1993, there found 5 planar magnetic structures according to the criteria (absolute value of Bn)/(absolute value of B) less than 0.1 for planarity and (dB)/(absolute value of B) greater than 0.7 for variability of magnetic field, where Bn, dB, and the absolute value of B are field component normal to a plane, standard deviation, and average of the magnitude of the magnetic field, respectively. Sources of 4 events were on low-latitude (less than 5 degrees) active regions from which loop-like structures were expanding. The coincidence, 80%, is extremely high with respect to accidental coincidence, 7%, of Sakigake windows of solar wind observation with active regions. The last source was on loop-like features which seemed to be related with a mid-latitude (20 degrees) active region.

  19. Kinetic temperatures toward X1/X2 orbit interceptions regions and giant molecular loops in the Galactic center region

    NASA Astrophysics Data System (ADS)

    Riquelme, D.; Amo-Baladrón, M. A.; Martín-Pintado, J.; Mauersberger, R.; Martín, S.; Bronfman, L.

    2013-01-01

    Context. It is well known that the kinetic temperatures, Tkin, of the molecular clouds in the Galactic center region are higher than in typical disk clouds. However, the Tkin of the molecular complexes found at higher latitudes towards the giant molecular loops in the central region of the Galaxy is so far unknown. The gas of these high-latitude molecular clouds (hereafter referred to as "halo clouds") is located in a region where the gas in the disk may interact with the gas in the halo in the Galactic center region. Aims: To derive Tkin in the molecular clouds at high latitude and understand the physical process responsible for the heating of the molecular gas both in the central molecular zone (the concentration of molecular gas in the inner ~500 pc) and in the giant molecular loops. Methods: We measured the metastable inversion transitions of NH3 from (J,K) = (1,1) to (6,6) toward six positions selected throughout the Galactic central disk and halo. We used rotational diagrams and large velocity gradient (LVG) modeling to estimate the kinetic temperatures toward all the sources. We also observed other molecules like SiO, HNCO, CS, C34S, C18O, and 13CO, to derive the densities and to trace different physical processes (shocks, photodissociation, dense gas) expected to dominate the heating of the molecular gas. Results: We derive for the first time Tkin of the high-latitude clouds interacting with the disk in the Galactic center region. We find high rotational temperatures in all the observed positions. We derive two kinetic temperature components (~150 K and ~40 K) for the positions in the central molecular zone, and only the warm kinetic temperature component for the clouds toward the giant molecular loops. The fractional abundances derived from the different molecules suggest that shocks provide the main heating mechanism throughout the Galactic center, also at high latitudes. Appendices A and B are available in electronic form at http://www.aanda.org

  20. Arrhenius temperature dependence of in vitro tissue plasminogen activator thrombolysis

    NASA Astrophysics Data System (ADS)

    Shaw, George J.; Dhamija, Ashima; Bavani, Nazli; Wagner, Kenneth R.; Holland, Christy K.

    2007-06-01

    Stroke is a devastating disease and a leading cause of death and disability. Currently, the only FDA approved therapy for acute ischemic stroke is the intravenous administration of the thrombolytic medication, recombinant tissue plasminogen activator (tPA). However, this treatment has many contraindications and can have dangerous side effects such as intra-cerebral hemorrhage. These treatment limitations have led to much interest in potential adjunctive therapies, such as therapeutic hypothermia (T <= 35 °C) and ultrasound enhanced thrombolysis. Such interest may lead to combining these therapies with tPA to treat stroke, however little is known about the effects of temperature on the thrombolytic efficacy of tPA. In this work, we measure the temperature dependence of the fractional clot mass loss Δm(T) resulting from tPA exposure in an in vitro human clot model. We find that the temperature dependence is well described by an Arrhenius temperature dependence with an effective activation energy Eeff of 42.0 ± 0.9 kJ mole-1. Eeff approximates the activation energy of the plasminogen-to-plasmin reaction of 48.9 kJ mole-1. A model to explain this temperature dependence is proposed. These results will be useful in predicting the effects of temperature in future lytic therapies.

  1. Changes in Sea Surface Temperature and North Atlantic Hurricane Activities

    NASA Astrophysics Data System (ADS)

    Nazari, R.; Mahani, S.; Khanbilvardi, R.

    2006-05-01

    People of United States from Maine to Texas in the years 1995 to 2005 experienced the highest level of North Atlantic hurricane activity in the reliable collected data and reports in compare with the generally low activity of the previous two decays (1970 to 1994). The greater activity might be a consequence of instantaneous changes in North Atlantic Sea Surface Temperature (SST) and air temperature. This thermal energy of increased Sea Surface Temperature (warm water) is known as tropical cyclone heat potential (TCHP) partly powers a hurricane and has been called hurricane fuel. In primary steps of this research we are trying to examine the association of variation of Sea Surface Temperature (SST), Sea Surface Height (SSH) and air temperature in the past decades with changes in hurricane number, duration and intensity. Preliminary analysis demonstrated that there is correlation between global warming and the occurrence of hurricanes because of the anticipated enhancement of energy available to the storms due to higher sea surface temperatures. The goal is to characterize and specify significant factors on tropical storms to improve the capability of predicting a hurricane and its damages to human lives and the economy. This information can be used to advise strategies for warning and also minimizing the magnitude of hurricane destruction, damages, and life losses.

  2. Elliptically Bent X-ray Mirrors with Active Temperature Stabilization

    SciTech Connect

    Yuan, Sheng; Church, Matthew; Yashchuk, Valeriy V.; Goldberg, Kenneth A.; Celestre, Rich; McKinney, Wayne R.; Kirschman, Jonathan; Morrison, Greg; Noll, Tino; Warwick, Tony; Padmore, Howard A.

    2010-01-31

    We present details of design of elliptically bent Kirkpatrick-Baez mirrors developed and successfully used at the Advanced Light Source for submicron focusing. A distinctive feature of the mirror design is an active temperature stabilization based on a Peltier element attached directly to the mirror body. The design and materials have been carefully optimized to provide high heat conductance between the mirror body and substrate. We describe the experimental procedures used when assembling and precisely shaping the mirrors, with special attention paid to laboratory testing of the mirror-temperature stabilization. For this purpose, the temperature dependence of the surface slope profile of a specially fabricated test mirror placed inside a temperature-controlled container was measured. We demonstrate that with active mirror-temperature stabilization, a change of the surrounding temperature by more than 3K does not noticeably affect the mirror figure. Without temperature stabilization, the surface slope changes by approximately 1.5 ?mu rad rms (primarily defocus) under the same conditions.

  3. Regional impacts of global change: seasonal trends in extreme rainfall, run-off and temperature in two contrasting regions of Morocco

    NASA Astrophysics Data System (ADS)

    Khomsi, Kenza; Mahe, Gil; Tramblay, Yves; Sinan, Mohamed; Snoussi, Maria

    2016-05-01

    In Morocco, socio-economic activities are highly vulnerable to extreme weather events. This study investigates trends in mean and extreme rainfall, run-off and temperature, as well as their relationship with large-scale atmospheric circulation. It focuses on two Moroccan watersheds: the subhumid climate region of Bouregreg in the north and the semi-arid region of Tensift in the south, using data from 1977 to 2003. The study is based on a set of daily temperature, precipitation and run-off time series retrieved from weather stations in the two regions. Results do not show a homogeneous behaviour in the two catchments; the influence of the large-scale atmospheric circulation is different and a clear spatial dependence of the trend analysis linked to the distance from the coast and the mountains can be observed. Overall, temperature trends are mostly positive in the studied area, while weak statistically significant trends can be identified in seasonal rainfall, extreme rainfall events, average run-off and extreme run-off events.

  4. Bimanual passive movement: functional activation and inter-regional coupling.

    PubMed

    Macaluso, Emiliano; Cherubini, Andrea; Sabatini, Umberto

    2007-01-01

    The aim of this study was to investigate intra-regional activation and inter-regional connectivity during passive movement. During fMRI, a mechanic device was used to move the subject's index and middle fingers. We assessed four movement conditions (unimanual left/right, bimanual symmetric/asymmetric), plus Rest. A conventional intra-regional analysis identified the passive stimulation network, including motor cortex, primary and secondary somatosensory cortex, plus the cerebellum. The posterior (sensory) part of the sensory-motor activation around the central sulcus showed a significant modulation according to the symmetry of the bimanual movement, with greater activation for asymmetric compared to symmetric movements. A second set of fMRI analyses assessed condition-dependent changes of coupling between sensory-motor regions around the superior central sulcus and the rest of the brain. These analyses showed a high inter-regional covariation within the entire network activated by passive movement. However, the specific experimental conditions modulated these patterns of connectivity. Highest coupling was observed during the Rest condition, and the coupling between homologous sensory-motor regions around the left and right central sulcus was higher in bimanual than unimanual conditions. These findings demonstrate that passive movement can affect the connectivity within the sensory-motor network. We conclude that implicit detection of asymmetry during bimanual movement relies on associative somatosensory region in post-central areas, and that passive stimulation reduces the functional connectivity within the passive movement network. Our findings open the possibility to combine passive movement and inter-regional connectivity as a tool to investigate the functionality of the sensory-motor system in patients with very poor mobility.

  5. Cloud Masking and Surface Temperature Distribution in the Polar Regions Using AVHRR and other Satellite Data

    NASA Technical Reports Server (NTRS)

    Comiso, Joey C.

    1995-01-01

    Surface temperature is one of the key variables associated with weather and climate. Accurate measurements of surface air temperatures are routinely made in meteorological stations around the world. Also, satellite data have been used to produce synoptic global temperature distributions. However, not much attention has been paid on temperature distributions in the polar regions. In the polar regions, the number of stations is very sparse. Because of adverse weather conditions and general inaccessibility, surface field measurements are also limited. Furthermore, accurate retrievals from satellite data in the region have been difficult to make because of persistent cloudiness and ambiguities in the discrimination of clouds from snow or ice. Surface temperature observations are required in the polar regions for air-sea-ice interaction studies, especially in the calculation of heat, salinity, and humidity fluxes. They are also useful in identifying areas of melt or meltponding within the sea ice pack and the ice sheets and in the calculation of emissivities of these surfaces. Moreover, the polar regions are unique in that they are the sites of temperature extremes, the location of which is difficult to identify without a global monitoring system. Furthermore, the regions may provide an early signal to a potential climate change because such signal is expected to be amplified in the region due to feedback effects. In cloud free areas, the thermal channels from infrared systems provide surface temperatures at relatively good accuracies. Previous capabilities include the use of the Temperature Humidity Infrared Radiometer (THIR) onboard the Nimbus-7 satellite which was launched in 1978. Current capabilities include the use of the Advance Very High Resolution Radiometer (AVHRR) aboard NOAA satellites. Together, these two systems cover a span of 16 years of thermal infrared data. Techniques for retrieving surface temperatures with these sensors in the polar regions have

  6. Problems in evaluating regional and local trends in temperature: An example from eastern Colorado, USA

    USGS Publications Warehouse

    Pielke, R.A.; Stohlgren, T.; Schell, L.; Parton, W.; Doesken, N.; Redmond, K.; Moeny, J.; McKee, T.; Kittel, T.G.F.

    2002-01-01

    We evaluated long-term trends in average maximum and minimum temperatures, threshold temperatures, and growing season in eastern Colorado, USA, to explore the potential shortcomings of many climate-change studies that either: (1) generalize regional patterns from single stations, single seasons, or a few parameters over short duration from averaging dissimilar stations: or (2) generalize an average regional pattern from coarse-scale general circulation models. Based on 11 weather stations, some trends were weakly regionally consistent with previous studies of night-time temperature warming. Long-term (80 + years) mean minimum temperatures increased significantly (P < 0.2) in about half the stations in winter, spring, and autumn and six stations had significant decreases in the number of days per year with temperatures ??? - 17.8 ??C (???0??F). However, spatial and temporal variation in the direction of change was enormous for all the other weather parameters tested, and, in the majority of tests, few stations showed significant trends (even at P < 0.2). In summer, four stations had significant increases and three stations had significant decreases in minimum temperatures, producing a strongly mixed regional signal. Trends in maximum temperature varied seasonally and geographically, as did trends in threshold temperature days ???32.2??C (???90??F) or days ???37.8??C (???100??F). There was evidence of a subregional cooling in autumn's maximum temperatures, with five stations showing significant decreasing trends. There were many geographic anomalies where neighbouring weather stations differed greatly in the magnitude of change or where they had significant and opposite trends. We conclude that sub-regional spatial and seasonal variation cannot be ignored when evaluating the direction and magnitude of climate change. It is unlikely that one or a few weather stations are representative of regional climate trends, and equally unlikely that regionally projected climate

  7. TARPs: Tracked Active Region Patches from SoHO/MDI

    NASA Astrophysics Data System (ADS)

    Turmon, M.; Hoeksema, J. T.; Bobra, M.

    2013-12-01

    We describe progress toward creating a retrospective MDI data product consisting of tracked magnetic features on the scale of solar active regions, abbreviated TARPs (Tracked Active Region Patches). The TARPs are being developed as a backward-looking extension (covering approximately 3500 regions spanning 1996-2010) to the HARP (HMI Active Region Patch) data product that has already been released for HMI (2010-present). Like the HARPs, the MDI TARP data set is designed to be a catalog of active regions (ARs), indexed by a region ID number, analogous to a NOAA AR number, and time. TARPs from MDI are computed based on the 96-minute synoptic magnetograms and pseudo-continuum intensitygrams. As with the related HARP data product, the approximate threshold for significance is 100G. Use of both image types together allows faculae and sunspots to be separated out as sub-classes of activity, in addition to identifying the overall active region that the faculae/sunspots are part of. After being identified in single images, the magnetically-active patches are grouped and tracked from image to image. Merges among growing active regions, as well as faint active regions hovering at the threshold of detection, are handled automatically. Regions are tracked from their inception until they decay within view, or transit off the visible disk. The final data product is indexed by a nominal AR number and time. For each active region and for each time, a bitmap image is stored containing the precise outline of the active region. Additionaly, metadata such as areas and integrated fluxes are stored for each AR and for each time. Because there is a calibration between the HMI and MDI magnetograms (Liu, Hoeksema et al. 2012), it is straightforward to use the same classification and tracking rules for the HARPs (from HMI) and the MDI TARPs. We anticipate that this will allow a consistent catalog spanning both instruments. We envision several uses for the TARP data product, which will be

  8. Communication: Effective temperature and glassy dynamics of active matter.

    PubMed

    Wang, Shenshen; Wolynes, Peter G

    2011-08-07

    A systematic expansion of the many-body master equation for active matter, in which motors power configurational changes as in the cytoskeleton, is shown to yield a description of the steady state and responses in terms of an effective temperature. The effective temperature depends on the susceptibility of the motors and a Peclet number which measures their strength relative to thermal Brownian diffusion. The analytic prediction is shown to agree with previous numerical simulations and experiments. The mapping also establishes a description of aging in active matter that is also kinetically jammed.

  9. Glass transition temperatures and fermentative activity of heat-treated commercial active dry yeasts.

    PubMed

    Schebor, C; Galvagno, M; del Pilar Buera, M; Chirife, J

    2000-01-01

    Differential scanning calorimetry thermograms of various samples of commercial instant active dry yeasts revealed a clear glass transition typical of amorphous carbohydrates and sugars. The resulting glass transition temperatures were found to decrease with increasing moisture content. The observed glass curve was similar to that of pure trehalose, which is known to accumulate in large amounts in baker's yeast. The effect of heat treatment at various temperatures on the fermentative activity (as measured by the metabolic production of CO(2)) of dry yeast was studied. First-order plots were obtained representing the loss of fermentative activity as a function of heating time at the various temperatures assayed. Significant losses of fermentative activity were observed in vitrified yeast samples. The dependence of rate constants with temperature was found to follow Arrhenius behavior. The relationship between the loss of fermentative activity and glass transition was not verified, and the glass transition was not reflected on the temperature dependence of fermentative activity loss.

  10. Warming Amplification of Minimum and Maximum Temperatures over High-Elevation Regions across the Globe.

    PubMed

    Fan, Xiaohui; Wang, Qixiang; Wang, Mengben; Jiménez, Claudia Villarroel

    2015-01-01

    An analysis of the annual mean temperature (TMEAN) (1961-2010) has revealed that warming amplification (altitudinal amplification and regional amplification) is a common feature of major high-elevation regions across the globe against the background of global warming since the mid-20th century. In this study, the authors further examine whether this holds for annual mean minimum temperature (TMIN) and annual mean maximum temperature (TMAX) (1961-2010) on a global scale. The extraction method of warming component of altitude, and the paired region comparison method were used in this study. Results show that a significant altitudinal amplification trend in TMIN (TMAX) is detected in all (four) of the six high-elevation regions tested, and the average magnitude of altitudinal amplification trend for TMIN (TMAX) [0.306±0.086 °C km-1(0.154±0.213 °C km-1)] is substantially larger (smaller) than TMEAN (0.230±0.073 °C km-1) during the period 1961-2010. For the five paired high- and low-elevation regions available, regional amplification is detected in the four high-elevation regions for TMIN and TMAX (respectively or as a whole). Qualitatively, highly (largely) consistent results are observed for TMIN (TMAX) compared with those for TMEAN.

  11. CONTRACTING AND ERUPTING COMPONENTS OF SIGMOIDAL ACTIVE REGIONS

    SciTech Connect

    Liu Rui; Wang Yuming; Liu Chang; Wang Haimin; Toeroek, Tibor

    2012-10-01

    It has recently been 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 GOES class B to class X. Owing to the high-sensitivity and broad temperature coverage of the Atmospheric Imaging Assembly (AIA) on board 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), it also precedes the increase in GOES soft X-ray fluxes. In the more energetic events, the eruption is simultaneous with the impulsive phase of the nonthermal hard X-ray emission. These observations confirm that loop contraction is an integrated process in eruptions with partially opened arcades. The consequence of contraction is a new equilibrium with reduced magnetic energy, as the contracting loops never regain their original positions. The contracting process is a direct consequence of flare energy release, as evidenced by the strong correlation of the maximal contracting speed, and strong anti-correlation of the time delay of contraction relative to expansion, with the peak soft X-ray flux. This is also implied by the relationship between contraction and expansion, i.e., their timing and speed.

  12. Brain temperature fluctuation: a reflection of functional neural activation.

    PubMed

    Kiyatkin, Eugene A; Brown, P Leon; Wise, Roy A

    2002-07-01

    Although it is known that relatively large increases in local brain temperature can occur during behaviour and in response to various novel, stressful and emotionally arousing environmental stimuli, the source of this heat is not clearly established. To clarify this issue, we monitored the temperature in three brain structures (dorsal and ventral striatum, cerebellum) and in arterial blood at the level of the abdominal aorta in freely moving rats exposed to several environmental challenges ranging from traditional stressors to simple sensory stimuli (cage change, tail pinch, exposure to another male rat, a female rat, a mouse or an unexpected sound). We found that brain temperature was consistently higher than arterial blood temperature, and that brain temperature increased prior to, and to a greater extent than, the increase in blood temperature evoked by each test challenge. Thus, the local metabolic consequences of widely correlated neural activity appear to be the primary source of increases in brain temperature and a driving force behind the associated changes in body temperature.

  13. AMR (Active Magnetic Regenerative) refrigeration for low temperature

    NASA Astrophysics Data System (ADS)

    Jeong, Sangkwon

    2014-07-01

    This paper reviews AMR (Active Magnetic Regenerative) refrigeration technology for low temperature applications that is a novel cooling method to expand the temperature span of magnetic refrigerator. The key component of the AMR system is a porous magnetic regenerator which allows a heat transfer medium (typically helium gas) to flow through it and therefore obviate intermittently operating an external heat switch. The AMR system alternatingly heats and cools the heat transfer medium by convection when the magneto-caloric effect is created under varying magnetic field. AMR may extend the temperature span for wider range than ADR (Adiabatic Demagnetization Refrigerator) at higher temperatures above 10 K because magneto-caloric effects are typically concentrated in a small temperature range in usual magnetic refrigerants. The regenerative concept theoretically enables each magnetic refrigerant to experience a pseudo-Carnot magnetic refrigeration cycle in a wide temperature span if it is properly designed, although adequate thermodynamic matching of strongly temperature-dependent MCE (magneto-caloric effect) of the regenerator material and the heat capacity of fluid flow is often tricky due to inherent characteristics of magnetic materials. This paper covers historical developments, fundamental concepts, key components, applications, and recent research trends of AMR refrigerators for liquid helium or liquid hydrogen temperatures.

  14. Relation of Vegetation and Temperature Condition Indices (1981-1999) and Drought conditions in Indian Region

    NASA Astrophysics Data System (ADS)

    Kanwar, R.; Narayan, U.; Kumar, M.

    The Advanced Very High Resolution Radiometer (AVHRR) onboard NOAA series of satellites has been used for regional and global vegetation coverage since 1978 employing the Normalized Difference Vegetation Index (NDVI). Recently, this technique has been improved combining NDVI with one of the thermal channels and converting them into the vegetation condition Index (VCI) and Temperature condition Index (TCI). W e have analysed NDVI, Vegetation and Temperature Condition Indices for the year 1981-1999 to the map the state of vegetation for Indian regions. Further, we have correlated these indices with the crop yield and crop production for different parts of India. The NDVI is also correlated with the scattering index derived form ERS data. The preset study shows that scattering coefficient, the NDVI, vegetation and temperature condition indices can be employed together in monitoring drought conditions and the vegetation vigor of Indian regions.

  15. Unusually high soil nitrogen oxide emissions influence air quality in a high-temperature agricultural region

    PubMed Central

    Oikawa, P. Y.; Ge, C.; Wang, J.; Eberwein, J. R.; Liang, L. L.; Allsman, L. A.; Grantz, D. A.; Jenerette, G. D.

    2015-01-01

    Fertilized soils have large potential for production of soil nitrogen oxide (NOx=NO+NO2), however these emissions are difficult to predict in high-temperature environments. Understanding these emissions may improve air quality modelling as NOx contributes to formation of tropospheric ozone (O3), a powerful air pollutant. Here we identify the environmental and management factors that regulate soil NOx emissions in a high-temperature agricultural region of California. We also investigate whether soil NOx emissions are capable of influencing regional air quality. We report some of the highest soil NOx emissions ever observed. Emissions vary nonlinearly with fertilization, temperature and soil moisture. We find that a regional air chemistry model often underestimates soil NOx emissions and NOx at the surface and in the troposphere. Adjusting the model to match NOx observations leads to elevated tropospheric O3. Our results suggest management can greatly reduce soil NOx emissions, thereby improving air quality. PMID:26556236

  16. Unusually high soil nitrogen oxide emissions influence air quality in a high-temperature agricultural region.

    PubMed

    Oikawa, P Y; Ge, C; Wang, J; Eberwein, J R; Liang, L L; Allsman, L A; Grantz, D A; Jenerette, G D

    2015-11-10

    Fertilized soils have large potential for production of soil nitrogen oxide (NOx=NO+NO2), however these emissions are difficult to predict in high-temperature environments. Understanding these emissions may improve air quality modelling as NOx contributes to formation of tropospheric ozone (O3), a powerful air pollutant. Here we identify the environmental and management factors that regulate soil NOx emissions in a high-temperature agricultural region of California. We also investigate whether soil NOx emissions are capable of influencing regional air quality. We report some of the highest soil NOx emissions ever observed. Emissions vary nonlinearly with fertilization, temperature and soil moisture. We find that a regional air chemistry model often underestimates soil NOx emissions and NOx at the surface and in the troposphere. Adjusting the model to match NOx observations leads to elevated tropospheric O3. Our results suggest management can greatly reduce soil NOx emissions, thereby improving air quality.

  17. On the temperature and gas composition in the region of comet formation

    NASA Astrophysics Data System (ADS)

    Bar-Nun, A.; Kleinfeld, I.

    1989-08-01

    The gas composition and temperature in the region of Comet Halley's formation are estimated on the basis of Giotto and Vega spacecraft results, in conjunction with an experimental study of gas-mixture trapping in amorphous water ice. A CO/CH4 ratio of the order of 100, and temperature about 48 K, are inferred for the case of Halley formation in the solar nebula through water vapor condensation in the presence of gas. This formation temperature, which implies that the ice was in amorphous form, is noted to be close to the temperatures observed in circumstellar dust shells by IRAS; it also lends support to the suggestion that short-period comets were formed outside the planet-formation region.

  18. Regional climates in the GISS general circulation model: Surface air temperature

    NASA Technical Reports Server (NTRS)

    Hewitson, Bruce

    1994-01-01

    One of the more viable research techniques into global climate change for the purpose of understanding the consequent environmental impacts is based on the use of general circulation models (GCMs). However, GCMs are currently unable to reliably predict the regional climate change resulting from global warming, and it is at the regional scale that predictions are required for understanding human and environmental responses. Regional climates in the extratropics are in large part governed by the synoptic-scale circulation and the feasibility of using this interscale relationship is explored to provide a way of moving to grid cell and sub-grid cell scales in the model. The relationships between the daily circulation systems and surface air temperature for points across the continental United States are first developed in a quantitative form using a multivariate index based on principal components analysis (PCA) of the surface circulation. These relationships are then validated by predicting daily temperature using observed circulation and comparing the predicted values with the observed temperatures. The relationships predict surface temperature accurately over the major portion of the country in winter, and for half the country in summer. These relationships are then applied to the surface synoptic circulation of the Goddard Institute for Space Studies (GISS) GCM control run, and a set of surface grid cell temperatures are generated. These temperatures, based on the larger-scale validated circulation, may now be used with greater confidence at the regional scale. The generated temperatures are compared to those of the model and show that the model has regional errors of up to 10 C in individual grid cells.

  19. Discrepancies between the [O iii] and [S iii] temperatures in H ii regions

    NASA Astrophysics Data System (ADS)

    Binette, L.; Matadamas, R.; Hägele, G. F.; Nicholls, D. C.; Magris C., G.; Peña-Guerrero, M. Á.; Morisset, C.; Rodríguez-González, A.

    2012-11-01

    Context. Analysis of published [O iii] and [S iii] temperatures measurements of emission line objects consisting of Hii galaxies, giant extragalactic Hii regions, Galactic Hii regions, and Hii regions from the Magellanic Clouds reveal that the [O iii] temperatures are higher than the corresponding values from [S iii] in most objects with gas metallicities in excess of 0.2 solar. For the coolest nebulae (the highest metallicities), the [O iii] temperature excess can reach ~3000 K. Aims: We look for an explanation for these temperature differences and explore the parameter space of models with the aim of reproducing the observed trend of TO iii > TS iii in Hii regions with temperatures below 14 000 K. Methods: Using standard photoionization models, we varied the ionization parameter, the hardness of the ionizing continuum, and the gas metallicities in order to characterize how models behave with respect to the observations. We introduced temperature inhomogeneities and varied their mean squared amplitude t2 . We explored the possibility of inhomogeneities in abundances by combining two models of widely different metallicity. We calculated models that consider the possibility of a non-Maxwell-Boltzmann energy distribution (a κ-distribution) for the electron energies. We also considered shock heating within the photoionized nebula. Results: Simple photoionization calculations yield nearly equal [O iii] and [S iii] temperatures in the domain of interest. Hence these models fail to reproduce the [O iii] temperature excess. Models that consider temperature inhomogeneities, as measured by the mean squared amplitude t2 , also fail in the regime where TO iii < 14 000 K. Three options remain that can reproduce the observed excess in TO iii temperatures: (1) large metallicity inhomogeneities in the nebula; a (2) κ-distribution for the electron energies; and (3) shock waves that propagate in the photoionized plasma at velocities ~60 km s-1. Conclusions: The observed nebular

  20. Impacts of urban and industrial development on Arctic land surface temperature in Lower Yenisei River Region.

    NASA Astrophysics Data System (ADS)

    Li, Z.; Shiklomanov, N. I.

    2015-12-01

    Urbanization and industrial development have significant impacts on arctic climate that in turn controls settlement patterns and socio-economic processes. In this study we have analyzed the anthropogenic influences on regional land surface temperature of Lower Yenisei River Region of the Russia Arctic. The study area covers two consecutive Landsat scenes and includes three major cities: Norilsk, Igarka and Dudingka. Norilsk industrial region is the largest producer of nickel and palladium in the world, and Igarka and Dudingka are important ports for shipping. We constructed a spatio-temporal interpolated temperature model by including 1km MODIS LST, field-measured climate, Modern Era Retrospective-analysis for Research and Applications (MERRA), DEM, Landsat NDVI and Landsat Land Cover. Those fore-mentioned spatial data have various resolution and coverage in both time and space. We analyzed their relationships and created a monthly spatio-temporal interpolated surface temperature model at 1km resolution from 1980 to 2010. The temperature model then was used to examine the characteristic seasonal LST signatures, related to several representative assemblages of Arctic urban and industrial infrastructure in order to quantify anthropogenic influence on regional surface temperature.

  1. Analysis of Future High Temperature Region in Urban Area under Climate Change Scenarios

    NASA Astrophysics Data System (ADS)

    Park, C.; Jeong, W.; Sung, S.; Park, J.

    2015-12-01

    Urban air temperature is higher than surrounding air temperature. It is called Urban Heat Island. Furthermore, according to climate change, Urban air temperature is expected to be increased in the future. Therefore, Preparing for high temperature event result from climate change is important as well as preparing for presence of the urban heat. In this study, we analyzed Seoul temperature change according to the climate change scenarios, and suggested some strategies to fight against climate change and urban heat island. For doing this, Firstly, Seoul was divided into 1km² cells which matches the climate change scenario resolution. Then, future temperature distribution was analyzed. In this time, future temperature means distribution means the average temperature in August 2010~2100 from Representative Concentration Pathways (RCPs) 4.5 and 8.5 scenarios. Secondly, Cells where temperature is over 33℃ are selected as the "high temperature region (HTR)". For identifying HTUR characteristics, we did regression analysis with terrain, land cover, distance from rivers and mountains variables. As a result, most of the HTR was distributed to the industrial and business districts, and appeared as far away from the rivers and mountains. These result can be used in the further urban heat island studies, especially identifying urban type which vulnerable to climate change. Also, it can be helpful in establishing strategies corresponding to the future climate.

  2. Effects of regional temperature on electric vehicle efficiency, range, and emissions in the United States.

    PubMed

    Yuksel, Tugce; Michalek, Jeremy J

    2015-03-17

    We characterize the effect of regional temperature differences on battery electric vehicle (BEV) efficiency, range, and use-phase power plant CO2 emissions in the U.S. The efficiency of a BEV varies with ambient temperature due to battery efficiency and cabin climate control. We find that annual energy consumption of BEVs can increase by an average of 15% in the Upper Midwest or in the Southwest compared to the Pacific Coast due to temperature differences. Greenhouse gas (GHG) emissions from BEVs vary primarily with marginal regional grid mix, which has three times the GHG intensity in the Upper Midwest as on the Pacific Coast. However, even within a grid region, BEV emissions vary by up to 22% due to spatial and temporal ambient temperature variation and its implications for vehicle efficiency and charging duration and timing. Cold climate regions also encounter days with substantial reduction in EV range: the average range of a Nissan Leaf on the coldest day of the year drops from 70 miles on the Pacific Coast to less than 45 miles in the Upper Midwest. These regional differences are large enough to affect adoption patterns and energy and environmental implications of BEVs relative to alternatives.

  3. On the Active Region Bright Grains Observed in the Transition Region Imaging Channels of IRIS

    NASA Astrophysics Data System (ADS)

    Skogsrud, H.; Rouppe van der Voort, L.; De Pontieu, B.

    2016-02-01

    The Interface Region Imaging Spectrograph (IRIS) provides spectroscopy and narrow band slit-jaw (SJI) imaging of the solar chromosphere and transition region at unprecedented spatial and temporal resolutions. Combined with high-resolution context spectral imaging of the photosphere and chromosphere as provided by the Swedish 1 m Solar Telescope (SST), we can now effectively trace dynamic phenomena through large parts of the solar atmosphere in both space and time. IRIS SJI 1400 images from active regions, which primarily sample the transition region with the Si iv 1394 and 1403 Å lines, reveal ubiquitous bright “grains” which are short-lived (two to five minute) bright roundish small patches of sizes 0.″5-1.″7 that generally move limbward with velocities up to about 30 km s-1. In this paper, we show that many bright grains are the result of chromospheric shocks impacting the transition region. These shocks are associated with dynamic fibrils (DFs), most commonly observed in Hα. We find that the grains show the strongest emission in the ascending phase of the DF, that the emission is strongest toward the top of the DF, and that the grains correspond to a blueshift and broadening of the Si iv lines. We note that the SJI 1400 grains can also be observed in the SJI 1330 channel which is dominated by C ii lines. Our observations show that a significant part of the active region transition region dynamics is driven from the chromosphere below rather than from coronal activity above. We conclude that the shocks that drive DFs also play an important role in the heating of the upper chromosphere and lower transition region.

  4. ON THE ACTIVE REGION BRIGHT GRAINS OBSERVED IN THE TRANSITION REGION IMAGING CHANNELS OF IRIS

    SciTech Connect

    Skogsrud, H.; Voort, L. Rouppe van der; Pontieu, B. De

    2016-02-01

    The Interface Region Imaging Spectrograph (IRIS) provides spectroscopy and narrow band slit-jaw (SJI) imaging of the solar chromosphere and transition region at unprecedented spatial and temporal resolutions. Combined with high-resolution context spectral imaging of the photosphere and chromosphere as provided by the Swedish 1 m Solar Telescope (SST), we can now effectively trace dynamic phenomena through large parts of the solar atmosphere in both space and time. IRIS SJI 1400 images from active regions, which primarily sample the transition region with the Si iv 1394 and 1403 Å lines, reveal ubiquitous bright “grains” which are short-lived (two to five minute) bright roundish small patches of sizes 0.″5–1.″7 that generally move limbward with velocities up to about 30 km s{sup −1}. In this paper, we show that many bright grains are the result of chromospheric shocks impacting the transition region. These shocks are associated with dynamic fibrils (DFs), most commonly observed in Hα. We find that the grains show the strongest emission in the ascending phase of the DF, that the emission is strongest toward the top of the DF, and that the grains correspond to a blueshift and broadening of the Si iv lines. We note that the SJI 1400 grains can also be observed in the SJI 1330 channel which is dominated by C ii lines. Our observations show that a significant part of the active region transition region dynamics is driven from the chromosphere below rather than from coronal activity above. We conclude that the shocks that drive DFs also play an important role in the heating of the upper chromosphere and lower transition region.

  5. Regional change in snow water equivalent-surface air temperature relationship over Eurasia during boreal spring

    NASA Astrophysics Data System (ADS)

    Wu, Renguang; Chen, Shangfeng

    2016-10-01

    Present study investigates local relationship between surface air temperature and snow water equivalent (SWE) change over mid- and high-latitudes of Eurasia during boreal spring. Positive correlation is generally observed around the periphery of snow covered region, indicative of an effect of snow on surface temperature change. In contrast, negative correlation is usually found over large snow amount area, implying a response of snow change to wind-induced surface temperature anomalies. With the seasonal retreat of snow covered region, region of positive correlation between SWE and surface air temperature shifts northeastward from March to May. A diagnosis of surface heat flux anomalies in April suggests that the snow impact on surface air temperature is dominant in east Europe and west Siberia through modulating surface shortwave radiation. In contrast, atmospheric effect on SWE is important in Siberia and Russia Far East through wind-induced surface sensible heat flux change. Further analysis reveals that atmospheric circulation anomalies in association with snowmelt over east Siberia may be partly attributed to sea surface temperature anomalies in the North Atlantic and the atmospheric circulation anomaly pattern associated with snowmelt over Russia Far East has a close association with the Arctic Oscillation.

  6. Dual role of cerebral blood flow in regional brain temperature control in the healthy newborn infant.

    PubMed

    Iwata, Sachiko; Tachtsidis, Ilias; Takashima, Sachio; Matsuishi, Toyojiro; Robertson, Nicola J; Iwata, Osuke

    2014-10-01

    Small shifts in brain temperature after hypoxia-ischaemia affect cell viability. The main determinants of brain temperature are cerebral metabolism, which contributes to local heat production, and brain perfusion, which removes heat. However, few studies have addressed the effect of cerebral metabolism and perfusion on regional brain temperature in human neonates because of the lack of non-invasive cot-side monitors. This study aimed (i) to determine non-invasive monitoring tools of cerebral metabolism and perfusion by combining near-infrared spectroscopy and echocardiography, and (ii) to investigate the dependence of brain temperature on cerebral metabolism and perfusion in unsedated newborn infants. Thirty-two healthy newborn infants were recruited. They were studied with cerebral near-infrared spectroscopy, echocardiography, and a zero-heat flux tissue thermometer. A surrogate of cerebral blood flow (CBF) was measured using superior vena cava flow adjusted for cerebral volume (rSVC flow). The tissue oxygenation index, fractional oxygen extraction (FOE), and the cerebral metabolic rate of oxygen relative to rSVC flow (CMRO₂ index) were also estimated. A greater rSVC flow was positively associated with higher brain temperatures, particularly for superficial structures. The CMRO₂ index and rSVC flow were positively coupled. However, brain temperature was independent of FOE and the CMRO₂ index. A cooler ambient temperature was associated with a greater temperature gradient between the scalp surface and the body core. Cerebral oxygen metabolism and perfusion were monitored in newborn infants without using tracers. In these healthy newborn infants, cerebral perfusion and ambient temperature were significant independent variables of brain temperature. CBF has primarily been associated with heat removal from the brain. However, our results suggest that CBF is likely to deliver heat specifically to the superficial brain. Further studies are required to assess the

  7. Tooth whitening and temperature rise with two bleaching activation methods

    NASA Astrophysics Data System (ADS)

    Abu-ElMagd, D. M.; El-Sayad, I. I.; Abd El-Gawad, L. M.

    2009-02-01

    Objectives: To measure the tooth whitening and the surface and intra-pulpal temperature increase in vitro on extracted upper human incisors after chemical, zoom light and diode laser activated bleaching. Materials and Methods: Thirty caries-free upper human incisors were selected. Teeth were divided into three equal groups according to the methods of activation of the bleaching agent (n=10). A whitening gel containing hydrogen peroxide was applied to the buccal surface of all teeth. Group I was bleached using chemically activated hydrogen peroxide gel. Group II was bleached with high intensity advanced power zoom activation light, for three applications of 15 min each. Group III was bleached with diode laser activation technique, where the teeth were irradiated with 2 watt diode laser for three applications of 30 sec each. Degree of whitening was assessed using an image analysis system, while temperature rise was recorded using a thermocouple on the external tooth surface and intrapulpal. Results: The degree of whitening increased significantly in all groups. However, the percentage of whitening was not statistically significantly different between the three groups. In addition, group II showed statistically significant higher mean rise in both surface and pulp temperatures than group I and group III. Conclusions: Chemical bleaching produces the same whitening effect as zoom AP light and laser, with no surface or pulpal temperature rise. Laser application is faster and produces less surface and pulp temperature increase than zoom AP light. Diode lasers used to activate bleaching gels are not considered dangerous to the vitality of dental pulps using power settings of 2W.

  8. Tooth Whitening And Temperature Rise With Two Bleaching Activation Methods

    SciTech Connect

    Abu-ElMagd, D. M.; El-Sayad, I. I.; Abd El-Gawad, L. M.

    2009-09-27

    To measure the tooth whitening and the surface and Intrapulpal temperature increase in vitro on freshly extracted upper human central incisors after chemical, Zoom AP light and diode laser activated bleaching. Thirty caries-free upper human incisors were selected. Teeth were divided into three equal groups according to the methods of activation of the bleaching agent (n = 10). A whitening gel containing hydrogen peroxide was applied to the buccal surface of all teeth. Group I was bleached using chemically activated hydrogen peroxide gel, for three applications of 15 min each. Group II was bleached with high intensity advanced power Zoom activation light (Zoom AP), for three applications of 15 min each. Group III was bleached with diode laser activation technique, where the teeth were irradiated with 2 Watt diode laser for three applications of 30 sec each. The whitening degree was assessed using an image analysis system, while temperature rise was recorded using a thermocouple on the external tooth surface and Intrapulpal. The degree of whitening increased significantly in all groups. However, the percentage of whitening was not statistically significantly different between the three groups. In addition, group II showed statistically significant higher mean rise in both surface and pulp temperatures than group I and group III. Chemical bleaching produces the same whitening effect as Zoom AP light and laser, with no surface or pulpal temperature rise. Laser application is faster and produces less surface and pulp temperature increase than Zoom AP light. Diode laser used to activate bleaching gels is not considered dangerous to the vitality of dental pulp using power settings of 2 W.

  9. Tooth Whitening And Temperature Rise With Two Bleaching Activation Methods

    NASA Astrophysics Data System (ADS)

    Abu-ElMagd, D. M.; El-Sayad, I. I.; Abd El-Gawad, L. M.

    2009-09-01

    To measure the tooth whitening and the surface and Intrapulpal temperature increase in vitro on freshly extracted upper human central incisors after chemical, Zoom AP light and diode laser activated bleaching. Thirty caries-free upper human incisors were selected. Teeth were divided into three equal groups according to the methods of activation of the bleaching agent (n = 10). A whitening gel containing hydrogen peroxide was applied to the buccal surface of all teeth. Group I was bleached using chemically activated hydrogen peroxide gel, for three applications of 15 min each. Group II was bleached with high intensity advanced power Zoom activation light (Zoom AP), for three applications of 15 min each. Group III was bleached with diode laser activation technique, where the teeth were irradiated with 2 Watt diode laser for three applications of 30 sec each. The whitening degree was assessed using an image analysis system, while temperature rise was recorded using a thermocouple on the external tooth surface and Intrapulpal. The degree of whitening increased significantly in all groups. However, the percentage of whitening was not statistically significantly different between the three groups. In addition, group II showed statistically significant higher mean rise in both surface and pulp temperatures than group I and group III. Chemical bleaching produces the same whitening effect as Zoom AP light and laser, with no surface or pulpal temperature rise. Laser application is faster and produces less surface and pulp temperature increase than Zoom AP light. Diode laser used to activate bleaching gels is not considered dangerous to the vitality of dental pulp using power settings of 2 W.

  10. In Situ Thermal Ion Temperature Measurements in the E Region Ionosphere: Techniques, Results, and Limitations

    NASA Astrophysics Data System (ADS)

    Burchill, J. K.; Archer, W. E.; Clemmons, J. H.; Knudsen, D. J.; Nicolls, M. J.

    2011-12-01

    In situ measurements of thermal ion temperature are rare at E region altitudes, which are too low for satellites. Here we present ion temperature measurements from a Thermal Ion Imager (TII) that flew on NASA sounding rocket 36.234 (the "Joule-2" mission) into the nightside E region ionosphere on 19 January 2007 from Poker Flat, AK. The TII is an electrostatic ion energy/angle imager that provides 2D ion distributions at 8 ms resolution. Ion temperatures are derived at altitudes between 100 km and 190 km by modelling the detector total count rate versus ion bulk flow angle with respect to the plane of the imager's field of view. Modelling this count rate spin profile shows that the analysis technique is robust against a number of error sources, including variability in payload floating potential, ion upflow, and aperture widening due to reflections from electrode surfaces. A significant uncertainty is associated with the average mass of the ions, which is not measured independently. Using the International Reference Ionosphere model to estimate ion mass, we obtain an ion temperature of 1300 K at 125 km, increasing to more than 3000 K at 180 km. These temperatures are much larger than neutral temperatures obtained from an ionization gauge on the same rocket (Tn˜500 K at 125 km, ˜600 K at 180 km), and do not agree with incoherent scatter radar observations in the vicinity of the rocket. These anomalous ion temperatures are, however, consistent with results from an independent analysis of the shape of the ion distribution images from a similar instrument on a separate payload flown 10 minutes earlier [Archer, MSc Thesis, University of Calgary, 2009]. We conclude that the high ion temperature readings are an artifact related to the environment in the vicinity of the probe, and investigate mechanisms for the cause. We discuss the implications of this effect for future in situ attempts to measure ion temperature in the E region ionosphere.

  11. Stress versus temperature dependence of activation energies for creep

    NASA Technical Reports Server (NTRS)

    Freed, A. D.; Raj, S. V.; Walker, K. P.

    1992-01-01

    The activation energy for creep at low stresses and elevated temperatures is associated with lattice diffusion, where the rate controlling mechanism for deformation is dislocation climb. At higher stresses and intermediate temperatures, the rate controlling mechanism changes from dislocation climb to obstacle-controlled dislocation glide. Along with this change in deformation mechanism occurs a change in the activation energy. When the rate controlling mechanism for deformation is obstacle-controlled dislocation glide, it is shown that a temperature-dependent Gibbs free energy does better than a stress-dependent Gibbs free energy in correlating steady-state creep data for both copper and LiF-22mol percent CaF2 hypereutectic salt.

  12. Stress versus temperature dependent activation energies in creep

    NASA Technical Reports Server (NTRS)

    Freed, A. D.; Raj, S. V.; Walker, K. P.

    1990-01-01

    The activation energy for creep at low stresses and elevated temperatures is lattice diffusion, where the rate controlling mechanism for deformation is dislocation climb. At higher stresses and intermediate temperatures, the rate controlling mechanism changes from that of dislocation climb to one of obstacle-controlled dislocation glide. Along with this change, there occurs a change in the activation energy. It is shown that a temperature-dependent Gibbs free energy does a good job of correlating steady-state creep data, while a stress-dependent Gibbs free energy does a less desirable job of correlating the same data. Applications are made to copper and a LiF-22 mol. percent CaF2 hypereutectic salt.

  13. Elevated temperature creep properties for selected active metal braze alloys

    SciTech Connect

    Stephens, J.J.

    1997-02-01

    Active metal braze alloys reduce the number of processes required for the joining of metal to ceramic components by eliminating the need for metallization and/or Ni plating of the ceramic surfaces. Titanium (Ti), V, and Zr are examples of active element additions which have been used successfully in such braze alloys. Since the braze alloy is expected to accommodate thermal expansion mismatch strains between the metal and ceramic materials, a knowledge of its elevated temperature mechanical properties is important. In particular, the issue of whether or not the creep strength of an active metal braze alloy is increased or decreased relative to its non-activated counterpart is important when designing new brazing processes and alloy systems. This paper presents a survey of high temperature mechanical properties for two pairs of conventional braze alloys and their active metal counterparts: (a) the conventional 72Ag-28Cu (Cusil) alloy, and the active braze alloy 62.2Ag- 36.2Cu-1.6Ti (Cusil ABA), and (b) the 82Au-18Ni (Nioro) alloy and the active braze alloy Mu-15.5M-0.75Mo-1.75V (Nioro ABA). For the case of the Cusil/Cusil ABA pair, the active metal addition contributes to solid solution strengthening of the braze alloy, resulting in a higher creep strength as compared to the non-active alloy. In the case of the Nioro/Nioro ABA pair, the Mo and V additions cause the active braze alloy to have a two-phase microstructure, which results in a reduced creep strength than the conventional braze alloy. The Garofalo sinh equation has been used to quantitatively describe the stress and temperature dependence of the deformation behavior. It will be observed that the effective stress exponent in the Garofalo sinh equation is a function of the instantaneous value of the stress argument.

  14. Projected changes in rainfall and temperature over homogeneous regions of India

    NASA Astrophysics Data System (ADS)

    Patwardhan, Savita; Kulkarni, Ashwini; Rao, K. Koteswara

    2016-11-01

    The impact of climate change on the characteristics of seasonal maximum and minimum temperature and seasonal summer monsoon rainfall is assessed over five homogeneous regions of India using a high-resolution regional climate model. Providing REgional Climate for Climate Studies (PRECIS) is developed at Hadley Centre for Climate Prediction and Research, UK. The model simulations are carried out over South Asian domain for the continuous period of 1961-2098 at 50-km horizontal resolution. Here, three simulations from a 17-member perturbed physics ensemble (PPE) produced using HadCM3 under the Quantifying Model Uncertainties in Model Predictions (QUMP) project of Hadley Centre, Met. Office, UK, have been used as lateral boundary conditions (LBCs) for the 138-year simulations of the regional climate model under Intergovernmental Panel on Climate Change (IPCC) A1B scenario. The projections indicate the increase in the summer monsoon (June through September) rainfall over all the homogeneous regions (15 to 19%) except peninsular India (around 5%). There may be marginal change in the frequency of medium and heavy rainfall events (>20 mm) towards the end of the present century. The analysis over five homogeneous regions indicates that the mean maximum surface air temperatures for the pre-monsoon season (March-April-May) as well as the mean minimum surface air temperature for winter season (January-February) may be warmer by around 4 °C towards the end of the twenty-first century.

  15. Regional temperature and precipitation changes under high-end (≥4°C) global warming.

    PubMed

    Sanderson, M G; Hemming, D L; Betts, R A

    2011-01-13

    Climate models vary widely in their projections of both global mean temperature rise and regional climate changes, but are there any systematic differences in regional changes associated with different levels of global climate sensitivity? This paper examines model projections of climate change over the twenty-first century from the Intergovernmental Panel on Climate Change Fourth Assessment Report which used the A2 scenario from the IPCC Special Report on Emissions Scenarios, assessing whether different regional responses can be seen in models categorized as 'high-end' (those projecting 4°C or more by the end of the twenty-first century relative to the preindustrial). It also identifies regions where the largest climate changes are projected under high-end warming. The mean spatial patterns of change, normalized against the global rate of warming, are generally similar in high-end and 'non-high-end' simulations. The exception is the higher latitudes, where land areas warm relatively faster in boreal summer in high-end models, but sea ice areas show varying differences in boreal winter. Many continental interiors warm approximately twice as fast as the global average, with this being particularly accentuated in boreal summer, and the winter-time Arctic Ocean temperatures rise more than three times faster than the global average. Large temperature increases and precipitation decreases are projected in some of the regions that currently experience water resource pressures, including Mediterranean fringe regions, indicating enhanced pressure on water resources in these areas.

  16. Socioeconomic and regional differences in active transportation in Brazil

    PubMed Central

    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

  17. Temperature and transmural region influence functional measurements in unloaded left ventricular cardiomyocytes

    PubMed Central

    Chung, Charles S; Campbell, Kenneth S

    2013-01-01

    Intact cardiomyocytes are increasingly being used to investigate the molecular mechanisms of contraction and to screen new therapeutic compounds. The function of the cardiomyocytes is often measured from the calcium transients and sarcomere length profiles. We studied the role of experimental temperature and transmural region on indices of function in freshly isolated, unloaded cardiomyocytes. Intact cardiomyocytes were isolated from the subendocardium, midmyocardium, and subepicardium of 3-month-old Sprague-Dawley rats. Myocytes from each region were studied at 25°C, 31°C, and 37°C. Cytosolic calcium transients were measured using Fura-2 fluorescence, whereas sarcomere length shortening and relengthening profiles were measured using high-speed video capture. For both the calcium transients and sarcomere length profiles, the time to peak and the time to half relaxation decreased significantly with increasing temperature. Increasing temperature also raised the minimum and maximum calcium levels of all cells. Of note, there was a reduced coefficient of variation (standard deviation divided by the mean) at higher temperatures for calcium fluorescence amplitudes, time to peak calcium, and rates of sarcomeric shortening and relengthening. The amplitudes and minimum of the calcium transients were significantly dependent on transmural region, and several sarcomere length parameters exhibited statistical interactions between temperature and transmural region. Together, these results show that biological variability can be reduced by performing experiments at 37°C rather than at room temperature, and by isolating cells from a specific transmural region. Adopting these procedures will improve the statistical power of subsequent analyses and increase the efficiency of future experiments. PMID:24400159

  18. Urban, Rural, and Regional Variations in Physical Activity

    ERIC Educational Resources Information Center

    Martin, Sarah Levin; Kirkner, Gregory J.; Mayo, Kelly; Matthews, Charles E.; Durstine, Larry; Hebert, James R.

    2005-01-01

    Purpose: There is some speculation about geographic differences in physical activity (PA) levels. We examined the prevalence of physical inactivity (PIA) and whether US citizens met the recommended levels of PA across the United States. In addition, the association between PIA/PA and degree of urbanization in the 4 main US regions (Northeast,…

  19. Inferred flows of electric currents in solar active regions

    NASA Technical Reports Server (NTRS)

    Ding, Y. J.; Hong, Q. F.; Hagyard, M. J.; Deloach, A. C.

    1985-01-01

    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.

  20. IFLA General Conference, 1987. Division of Regional Activities. Papers.

    ERIC Educational Resources Information Center

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

    Six of the seven papers in this collection focus on regional library activities in Africa, Asia and Oceania, and Latin America and the Caribbean: (1) "Libraries and Information Services in a Changing World: The Challenges African Information Services Face at the End of the 1980s" (Dejen Abate, Ethiopia); (2) "The Computer and…

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

    PubMed

    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

    2016-05-03

    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.

  2. A solar cycle timing predictor - The latitude of active regions

    NASA Technical Reports Server (NTRS)

    Schatten, Kenneth H.

    1990-01-01

    A 'Spoerer butterfly' method is used to examine solar cycle 22. It is shown from the latitude of active regions that the cycle can now be expected to peak near November 1989 + or - 8 months, basically near the latter half of 1989.

  3. Unwinding motion of a twisted active region filament

    SciTech Connect

    Yan, X. L.; Xue, Z. K.; Kong, D. F.; Liu, J. H.; Xu, C. L.

    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.

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

    PubMed Central

    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

  5. Regional and local scale modeling of stream temperatures and spatio-temporal variation in thermal sensitivities.

    PubMed

    Hilderbrand, Robert H; Kashiwagi, Michael T; Prochaska, Anthony P

    2014-07-01

    Understanding variation in stream thermal regimes becomes increasingly important as the climate changes and aquatic biota approach their thermal limits. We used data from paired air and water temperature loggers to develop region-scale and stream-specific models of average daily water temperature and to explore thermal sensitivities, the slopes of air-water temperature regressions, of mostly forested streams across Maryland, USA. The region-scale stream temperature model explained nearly 90 % of the variation (root mean square error = 0.957 °C), with the mostly flat coastal plain streams having significantly higher thermal sensitivities than the steeper highlands streams with piedmont streams intermediate. Model R (2) for stream-specific models was positively related to a stream's thermal sensitivity. Both the regional and the stream-specific air-water temperature regression models benefited from including mean daily discharge from regional gaging stations, but the degree of improvement declined as a stream's thermal sensitivity increased. Although catchment size had no relationship to thermal sensitivity, steeper streams or those with greater amounts of forest in their upstream watershed were less thermally sensitive. The subset of streams with three or more summers of temperature data exhibited a wide range of annual variation in thermal sensitivity at a site, with the variation not attributable to discharge, precipitation patterns, or physical attributes of streams or their watersheds. Our findings are a useful starting point to better understand patterns in stream thermal regimes. However, a more spatially and temporally comprehensive monitoring network should increase understanding of stream temperature variation and its controls as climatic patterns change.

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

    NASA Astrophysics Data System (ADS)

    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 <3.5 km s-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 Å emission line (formed at 6 × 105 K) of 5.17 ± 5.37 km s-1 and average redshifts in the C IV 1548 and 1550 Å emission lines (formed at 1 × 105 K) of 13.94 ± 4.93 km s-1 and 14.91 ± 6.09 km s-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.

  7. Temperature dependence of amino acid side chain IR absorptions in the amide I' region.

    PubMed

    Anderson, Benjamin A; Literati, Alex; Ball, Borden; Kubelka, Jan

    2014-05-01

    Amide I' IR spectra are widely used for studies of structural changes in peptides and proteins as a function of temperature. Temperature dependent absorptions of amino acid side-chains that overlap the amide I' may significantly complicate the structural analyses. While the side-chain IR spectra have been investigated previously, thus far their dependence on temperature has not been reported. Here we present the study of the changes in the IR spectra with temperature for side-chain groups of aspartate, glutamate, asparagine, glutamine, arginine, and tyrosine in the amide I' region (in D2O). Band fitting analysis was employed to extract the temperature dependence of the individual spectral parameters, such as peak frequency, integrated intensity, band width, and shape. As expected, the side-chain IR bands exhibit significant changes with temperature. The majority of the spectral parameters, particularly the frequency and intensity, show linear dependence on temperature, but the direction and magnitude vary depending on the particular side-chain group. The exception is arginine, which exhibits a distinctly nonlinear frequency shift with temperature for its asymmetric CN3H5(+) bending signal, although a linear fit can account for this change to within ~1/3 cm(-1). The applicability of the determined spectral parameters for estimations of temperature-dependent side-chain absorptions in peptides and proteins are discussed.

  8. Evaluation of near-surface temperature, humidity, and equivalent temperature from regional climate models applied in type II downscaling

    NASA Astrophysics Data System (ADS)

    Pryor, S. C.; Schoof, J. T.

    2016-04-01

    Atmosphere-surface interactions are important components of local and regional climates due to their key roles in dictating the surface energy balance and partitioning of energy transfer between sensible and latent heat. The degree to which regional climate models (RCMs) represent these processes with veracity is incompletely characterized, as is their ability to capture the drivers of, and magnitude of, equivalent temperature (Te). This leads to uncertainty in the simulation of near-surface temperature and humidity regimes and the extreme heat events of relevance to human health, in both the contemporary and possible future climate states. Reanalysis-nested RCM simulations are evaluated to determine the degree to which they represent the probability distributions of temperature (T), dew point temperature (Td), specific humidity (q) and Te over the central U.S., the conditional probabilities of Td|T, and the coupling of T, q, and Te to soil moisture and meridional moisture advection within the boundary layer (adv(Te)). Output from all RCMs exhibits discrepancies relative to observationally derived time series of near-surface T, q, Td, and Te, and use of a single layer for soil moisture by one of the RCMs does not appear to substantially degrade the simulations of near-surface T and q relative to RCMs that employ a four-layer soil model. Output from MM5I exhibits highest fidelity for the majority of skill metrics applied herein, and importantly most realistically simulates both the coupling of T and Td, and the expected relationships of boundary layer adv(Te) and soil moisture with near-surface T and q.

  9. Improving Shade Modelling in a Regional River Temperature Model Using Fine-Scale LIDAR Data

    NASA Astrophysics Data System (ADS)

    Hannah, D. M.; Loicq, P.; Moatar, F.; Beaufort, A.; Melin, E.; Jullian, Y.

    2015-12-01

    Air temperature is often considered as a proxy of the stream temperature to model the distribution areas of aquatic species water temperature is not available at a regional scale. To simulate the water temperature at a regional scale (105 km²), a physically-based model using the equilibrium temperature concept and including upstream-downstream propagation of the thermal signal was developed and applied to the entire Loire basin (Beaufort et al., submitted). This model, called T-NET (Temperature-NETwork) is based on a hydrographical network topology. Computations are made hourly on 52,000 reaches which average 1.7 km long in the Loire drainage basin. The model gives a median Root Mean Square Error of 1.8°C at hourly time step on the basis of 128 water temperature stations (2008-2012). In that version of the model, tree shadings is modelled by a constant factor proportional to the vegetation cover on 10 meters sides the river reaches. According to sensitivity analysis, improving the shade representation would enhance T-NET accuracy, especially for the maximum daily temperatures, which are currently not very well modelized. This study evaluates the most efficient way (accuracy/computing time) to improve the shade model thanks to 1-m resolution LIDAR data available on tributary of the LoireRiver (317 km long and an area of 8280 km²). Two methods are tested and compared: the first one is a spatially explicit computation of the cast shadow for every LIDAR pixel. The second is based on averaged vegetation cover characteristics of buffers and reaches of variable size. Validation of the water temperature model is made against 4 temperature sensors well spread along the stream, as well as two airborne thermal infrared imageries acquired in summer 2014 and winter 2015 over a 80 km reach. The poster will present the optimal length- and crosswise scale to characterize the vegetation from LIDAR data.

  10. Simulation of regional temperature change effect of land cover change in agroforestry ecotone of Nenjiang River Basin in China

    NASA Astrophysics Data System (ADS)

    Liu, Tingxiang; Zhang, Shuwen; Yu, Lingxue; Bu, Kun; Yang, Jiuchun; Chang, Liping

    2016-02-01

    The Northeast China is one of typical regions experiencing intensive human activities within short time worldwide. Particularly, as the significant changes of agriculture land and forest, typical characteristics of pattern and process of agroforestry ecotone change formed in recent decades. The intensive land use change of agroforestry ecotone has made significant change for regional land cover, which had significant impact on the regional climate system elements and the interactions among them. This paper took agroforestry ecotone of Nenjiang River Basin in China as study region and simulated temperature change based on land cover change from 1950s to 1978 and from 1978 to 2010. The analysis of temperature difference sensitivity to land cover change based on Weather Research and Forecasting (WRF) model showed that the land cover change from 1950s to 1978 induced warming effect over all the study area, including the change of grassland to agriculture land, grassland to deciduous broad-leaved forest, and deciduous broad-leaved forest to shrub land. The land cover change from 1978 to 2010 induced cooling effect over all the study area, including the change of deciduous broad-leaved forest to agriculture land, grassland to agriculture land, shrub land to agriculture land, and deciduous broad-leaved forest to grassland. In addition, the warming and cooling effect of land cover change was more significant in the region scale than specific land cover change area.

  11. Regional differences in rat conjunctival ion transport activities.

    PubMed

    Yu, Dongfang; Thelin, William R; Rogers, Troy D; Stutts, M Jackson; Randell, Scott H; Grubb, Barbara R; Boucher, Richard C

    2012-10-01

    Active ion transport and coupled osmotic water flow are essential to maintain ocular surface health. We investigated regional differences in the ion transport activities of the rat conjunctivas and compared these activities with those of cornea and lacrimal gland. The epithelial sodium channel (ENaC), sodium/glucose cotransporter 1 (Slc5a1), transmembrane protein 16 (Tmem16a, b, f, and g), cystic fibrosis transmembrane conductance regulator (Cftr), and mucin (Muc4, 5ac, and 5b) mRNA expression was characterized by RT-PCR. ENaC proteins were measured by Western blot. Prespecified regions (palpebral, fornical, and bulbar) of freshly isolated conjunctival tissues and cell cultures were studied electrophysiologically with Ussing chambers. The transepithelial electrical potential difference (PD) of the ocular surface was also measured in vivo. The effect of amiloride and UTP on the tear volume was evaluated in lacrimal gland excised rats. All selected genes were detected but with different expression patterns. We detected αENaC protein in all tissues, βENaC in palpebral and fornical conjunctiva, and γENaC in all tissues except lacrimal glands. Electrophysiological studies of conjunctival tissues and cell cultures identified functional ENaC, SLC5A1, CFTR, and TMEM16. Fornical conjunctiva exhibited the most active ion transport under basal conditions amongst conjunctival regions. PD measurements confirmed functional ENaC-mediated Na(+) transport on the ocular surface. Amiloride and UTP increased tear volume in lacrimal gland excised rats. This study demonstrated that the different regions of the conjunctiva exhibited a spectrum of ion transport activities. Understanding the specific functions of distinct regions of the conjunctiva may foster a better understanding of the physiology maintaining hydration of the ocular surface.

  12. Regional differences in rat conjunctival ion transport activities

    PubMed Central

    Yu, Dongfang; Thelin, William R.; Rogers, Troy D.; Stutts, M. Jackson; Randell, Scott H.; Grubb, Barbara R.

    2012-01-01

    Active ion transport and coupled osmotic water flow are essential to maintain ocular surface health. We investigated regional differences in the ion transport activities of the rat conjunctivas and compared these activities with those of cornea and lacrimal gland. The epithelial sodium channel (ENaC), sodium/glucose cotransporter 1 (Slc5a1), transmembrane protein 16 (Tmem16a, b, f, and g), cystic fibrosis transmembrane conductance regulator (Cftr), and mucin (Muc4, 5ac, and 5b) mRNA expression was characterized by RT-PCR. ENaC proteins were measured by Western blot. Prespecified regions (palpebral, fornical, and bulbar) of freshly isolated conjunctival tissues and cell cultures were studied electrophysiologically with Ussing chambers. The transepithelial electrical potential difference (PD) of the ocular surface was also measured in vivo. The effect of amiloride and UTP on the tear volume was evaluated in lacrimal gland excised rats. All selected genes were detected but with different expression patterns. We detected αENaC protein in all tissues, βENaC in palpebral and fornical conjunctiva, and γENaC in all tissues except lacrimal glands. Electrophysiological studies of conjunctival tissues and cell cultures identified functional ENaC, SLC5A1, CFTR, and TMEM16. Fornical conjunctiva exhibited the most active ion transport under basal conditions amongst conjunctival regions. PD measurements confirmed functional ENaC-mediated Na+ transport on the ocular surface. Amiloride and UTP increased tear volume in lacrimal gland excised rats. This study demonstrated that the different regions of the conjunctiva exhibited a spectrum of ion transport activities. Understanding the specific functions of distinct regions of the conjunctiva may foster a better understanding of the physiology maintaining hydration of the ocular surface. PMID:22814399

  13. Rainfall and temperature changes and variability in the Upper East Region of Ghana

    NASA Astrophysics Data System (ADS)

    Issahaku, Abdul-Rahaman; Campion, Benjamin Betey; Edziyie, Regina

    2016-08-01

    The aim of the research was to assess the current trend and variation in rainfall and temperature in the Upper East Region, Ghana, using time series moving average analysis and decomposition methods. Meteorological data obtained from the Ghana Meteorological Agency in Accra, Ghana, from 1954 to 2014 were used in the models. The additive decomposition model was used to analyze the rainfall because the seasonal variation was relatively constant over time, while the multiplicative model was used for both the daytime and nighttime temperatures because their seasonal variations increase over time. The monthly maximum and the minimum values for the entire period were as follows: rainfall 455.50 and 0.00 mm, nighttime temperature 29.10°C and 13.25°C and daytime temperature 41.10°C and 26.10°C, respectively. Also, while rainfall was decreasing, nighttime and daytime temperatures were increasing in decadal times. Since both the daytime and nighttime temperatures were increasing and rainfall was decreasing, climate extreme events such as droughts could result and affect agriculture in the region, which is predominantly rain fed. Also, rivers, dams, and dugouts are likely to dry up in the region. It was also observed that there was much variation in rainfall making prediction difficult. Day temperatures were generally high with the months of March and April have been the highest. The months of December recorded the lowest night temperature. Inhabitants are therefore advised to sleep in well-ventilated rooms during the warmest months and wear protective clothing during the cold months to avoid contracting climate-related diseases.

  14. Correlation of irradiation data using activation fluences and irradiation temperature.

    NASA Technical Reports Server (NTRS)

    Lynch, J. H.

    1972-01-01

    A new method of correlating radiation damage data is tested using actual measured data taken from the open literature. This method, the activation fluence method, was found to be as accurate as other contemporary models with which it was compared. The new method also has several advantages over the other methods. The method employs a new entity, the activation fluence (time-integrated specific activation rate), as the independent variables in a regression model. Temperature at which the irradiation takes place is also a variable. Although the method was tested for a specific type of damage (change in nil-ductility transition temperature for A302-B steel) it has no inherent restrictions and is limited only by the imagination of the user.

  15. Analyzing the impact of ambient temperature indicators on transformer life in different regions of Chinese mainland.

    PubMed

    Bai, Cui-fen; Gao, Wen-Sheng; Liu, Tong

    2013-01-01

    Regression analysis is applied to quantitatively analyze the impact of different ambient temperature characteristics on the transformer life at different locations of Chinese mainland. 200 typical locations in Chinese mainland are selected for the study. They are specially divided into six regions so that the subsequent analysis can be done in a regional context. For each region, the local historical ambient temperature and load data are provided as inputs variables of the life consumption model in IEEE Std. C57.91-1995 to estimate the transformer life at every location. Five ambient temperature indicators related to the transformer life are involved into the partial least squares regression to describe their impact on the transformer life. According to a contribution measurement criterion of partial least squares regression, three indicators are conclusively found to be the most important factors influencing the transformer life, and an explicit expression is provided to describe the relationship between the indicators and the transformer life for every region. The analysis result is applicable to the area where the temperature characteristics are similar to Chinese mainland, and the expressions obtained can be applied to the other locations that are not included in this paper if these three indicators are known.

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

    PubMed

    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.

  17. Transcriptionally active genome regions are preferred targets for retrovirus integration.

    PubMed Central

    Scherdin, U; Rhodes, K; Breindl, M

    1990-01-01

    We have analyzed the transcriptional activity of cellular target sequences for Moloney murine leukemia virus integration in mouse fibroblasts. At least five of the nine random, unselected integration target sequences studied showed direct evidence for transcriptional activity by hybridization to nuclear run-on transcripts prepared from uninfected cells. At least four of the sequences contained multiple recognition sites for several restriction enzymes that cut preferentially in CpG-rich islands, indicating integration into 5' or 3' ends or flanking regions of genes. Assuming that only a minor fraction (less than 20%) of the genome is transcribed in mammalian cells, we calculated the probability that this association of retroviral integration sites with transcribed sequences is due to chance to be very low (1.6 x 10(-2]. Thus, our results strongly suggest that transcriptionally active genome regions are preferred targets for retrovirus integration. Images PMID:2296087

  18. Seasonal distribution of microbial activity in bioaerosols in the outdoor environment of the Qingdao coastal region

    NASA Astrophysics Data System (ADS)

    Zhong, Xi; Qi, Jianhua; Li, Hongtao; Dong, Lijie; Gao, Dongmei

    2016-09-01

    Microbial activities in the atmosphere can indicate the physiological processes of microorganisms and can indirectly affect cloud formation and environmental health. In this study, the microbial activity in bioaerosols collected in the Qingdao coastal region was investigated using the fluorescein diacetate (FDA) hydrolysis method to detect the enzyme activity of microorganisms. The results showed that the microbial activity ranged from 5.49 to 102 ng/m3 sodium fluorescein from March 2013 to February 2014; the average value was 34.4 ng/m3. Microbial activity has no statistical correlation with total microbial quantity. Multiple linear regression analysis showed that meteorological factors such as atmospheric temperature, relative humidity and wind speed accounted for approximately 35.7% of the variation of the microbial activity, although their individual impacts on microbial activity varied. According to the correlation analysis, atmospheric temperature and wind speed had a significant positive and negative influence on microbial activity, respectively, whereas relative humidity and wind direction had no significant influence. The seasonal distribution of microbial activity in bioaerosols was in the order of summer > autumn > winter > spring, with high fluctuations in the summer and autumn. Microbial activity in bioaerosols differed in different weather conditions such as the sunny, foggy, and hazy days of different seasons. Further in situ observations in different weather conditions at different times and places are needed to understand the seasonal distribution characteristics of microbial activity in bioaerosols and the influence factors of microbial activity.

  19. RESOLVING THE ELECTRON TEMPERATURE DISCREPANCIES IN H II REGIONS AND PLANETARY NEBULAE: {kappa}-DISTRIBUTED ELECTRONS

    SciTech Connect

    Nicholls, David C.; Dopita, Michael A.; Sutherland, Ralph S.

    2012-06-20

    The measurement of electron temperatures and metallicities in H II regions and planetary nebulae (PNe) has-for several decades-presented a problem: results obtained using different techniques disagree. What is worse, they disagree consistently. There have been numerous attempts to explain these discrepancies, but none has provided a satisfactory solution to the problem. In this paper, we explore the possibility that electrons in H II regions and PNe depart from a Maxwell-Boltzmann equilibrium energy distribution. We adopt a '{kappa}-distribution' for the electron energies. Such distributions are widely found in solar system plasmas, where they can be directly measured. This simple assumption is able to explain the temperature and metallicity discrepancies in H II regions and PNe arising from the different measurement techniques. We find that the energy distribution does not need to depart dramatically from an equilibrium distribution. From an examination of data from H II regions and PNe, it appears that {kappa} {approx}> 10 is sufficient to encompass nearly all objects. We argue that the kappa-distribution offers an important new insight into the physics of gaseous nebulae, both in the Milky Way and elsewhere, and one that promises significantly more accurate estimates of temperature and metallicity in these regions.

  20. Sea surface temperature 1871-2099 in 38 cells in the Caribbean region.

    PubMed

    Sheppard, Charles; Rioja-Nieto, Rodolfo

    2005-09-01

    Sea surface temperature (SST) data with monthly resolution are provided for 38 cells in the Caribbean Sea and Bahamas region, plus Bermuda. These series are derived from the HadISST1 data set for historical time (1871-1999) and from the HadCM3 coupled climate model for predicted SST (1950-2099). Statistical scaling of the forecast data sets are performed to produce confluent SST series according to a now established method. These SST series are available for download. High water temperatures in 1998 killed enormous amounts of corals in tropical seas, though in the Caribbean region the effects at that time appeared less marked than in the Indo-Pacific. However, SSTs are rising in accordance with world-wide trends and it has been predicted that temperature will become increasingly important in this region in the near future. Patterns of SST rise within the Caribbean region are shown, and the importance of sub-regional patterns within this biologically highly interconnected area are noted.

  1. Effects of activation energy and activation volume on the temperature-dependent viscosity of water.

    PubMed

    Kwang-Hua, Chu Rainer

    2016-08-01

    Water transport in a leaf is vulnerable to viscosity-induced changes. Recent research has suggested that these changes may be partially due to variation at the molecular scale, e.g., regulations via aquaporins, that induce reductions in leaf hydraulic conductance. What are the quantitative as well as qualitative changes in temperature-dependent viscosity due to the role of aquaporins in tuning activation energy and activation volume? Using the transition-state approach as well as the boundary perturbation method, we investigate temperature-dependent viscosity tuned by activation energy and activation volume. To validate our approach, we compare our numerical results with previous temperature-dependent viscosity measurements. The rather good fit between our calculations and measurements confirms our present approach. We have obtained critical parameters for the temperature-dependent (shear) viscosity of water that might be relevant to the increasing and reducing of leaf hydraulic conductance. These parameters are sensitive to temperature, activation energy, and activation volume. Once the activation energy increases, the (shear) viscosity of water increases. Our results also show that as the activation volume increases (say, 10^{-23}m^{3}), the (shear) viscosity of water decreases significantly and the latter induces the enhancing of leaf hydraulic conductance. Within the room-temperature regime, a small increase in the activation energy will increase the water viscosity or reduce the leaf hydraulic conductance. Our approach and results can be applied to diverse plant or leaf attributes.

  2. Effects of activation energy and activation volume on the temperature-dependent viscosity of water

    NASA Astrophysics Data System (ADS)

    Kwang-Hua, Chu Rainer

    2016-08-01

    Water transport in a leaf is vulnerable to viscosity-induced changes. Recent research has suggested that these changes may be partially due to variation at the molecular scale, e.g., regulations via aquaporins, that induce reductions in leaf hydraulic conductance. What are the quantitative as well as qualitative changes in temperature-dependent viscosity due to the role of aquaporins in tuning activation energy and activation volume? Using the transition-state approach as well as the boundary perturbation method, we investigate temperature-dependent viscosity tuned by activation energy and activation volume. To validate our approach, we compare our numerical results with previous temperature-dependent viscosity measurements. The rather good fit between our calculations and measurements confirms our present approach. We have obtained critical parameters for the temperature-dependent (shear) viscosity of water that might be relevant to the increasing and reducing of leaf hydraulic conductance. These parameters are sensitive to temperature, activation energy, and activation volume. Once the activation energy increases, the (shear) viscosity of water increases. Our results also show that as the activation volume increases (say, 10-23m3 ), the (shear) viscosity of water decreases significantly and the latter induces the enhancing of leaf hydraulic conductance. Within the room-temperature regime, a small increase in the activation energy will increase the water viscosity or reduce the leaf hydraulic conductance. Our approach and results can be applied to diverse plant or leaf attributes.

  3. Evidence for Steady Heating: Observations of an Active Region Core with Hinode and TRACE

    NASA Astrophysics Data System (ADS)

    Warren, Harry P.; Winebarger, Amy R.; Brooks, David H.

    2010-03-01

    The timescale for energy release is an important parameter for constraining the coronal heating mechanism. Observations of "warm" coronal loops (~1 MK) have indicated that the heating is impulsive and that coronal plasma is far from equilibrium. In contrast, observations at higher temperatures (~3 MK) have generally been consistent with steady heating models. Previous observations, however, have not been able to exclude the possibility that the high temperature loops are actually composed of many small-scale threads that are in various stages of heating and cooling and only appear to be in equilibrium. With new observations from the EUV Imaging Spectrometer and X-ray Telescope (XRT) on Hinode we have the ability to investigate the properties of high temperature coronal plasma in extraordinary detail. We examine the emission in the core of an active region and find three independent lines of evidence for steady heating. We find that the emission observed in XRT is generally steady for hours, with a fluctuation level of approximately 15% in an individual pixel. Short-lived impulsive heating events are observed, but they appear to be unrelated to the steady emission that dominates the active region. Furthermore, we find no evidence for warm emission that is spatially correlated with the hot emission, as would be expected if the high temperature loops are the result of impulsive heating. Finally, we also find that intensities in the "moss," the footpoints of high temperature loops, are consistent with steady heating models provided that we account for the local expansion of the loop from the base of the transition region to the corona. In combination, these results provide strong evidence that the heating in the core of an active region is effectively steady, that is, the time between heating events is short relative to the relevant radiative and conductive cooling times.

  4. Solar activity effects on the equatorial thermosphere temperature profile

    NASA Astrophysics Data System (ADS)

    Arduini, C.; Laneve, G.; Nobile, L.

    In this paper we present the effects of solar activity on the temperature profiles of the equatorial thermosphere as derived from the neutral density data collected by the San Marco 5 (SM5) satellite. This satellite flew during the increasing part of the solar cycle 22 (1988). It had a quasi-equatorial orbit, with inclination lower than 3 deg. The range of measurements, from April to December, allows the inference of seasonal and diurnal effects on the temperature profiles. The density data are collected every second along arcs of orbit lasting up to 50 minutes. The analysis of these densities has been already partially presented and provided evidence for several interesting features, in particular the vertical structure of the diurnal harmonic content and its seasonal variations. The temperatures derived from the same data set provide a useful complement to this picture. The SM5 satellite carried on board 5 instruments for studying the equatorial ionosphere and thermosphere, among them, the Drag Balance Instrument (DBI) for measuring the neutral density and the Ion Drift Meter and Potential Retarding Analyzer (IVI) that allow the evaluation of ions concentration, velocity and temperature. It is possible, therefore, to compare the neutral temperature derived from the neutral density data with the ion temperature given by the IVI.

  5. Active disturbance rejection control of temperature for ultrastable optical cavities.

    PubMed

    Pizzocaro, Marco; Calonico, Davide; Calosso, Claudio; Clivati, Cecilia; Costanzo, Giovanni A; Levi, Filippo; Mura, Alberto

    2013-02-01

    This paper describes the application of a novel active disturbance rejection control (ADRC) to the stabilization of the temperature of two ultra-stable Fabry-Perot cavities. The cavities are 10 cm long and entirely made of ultralow- expansion glass. The control is based on a linear extended state observer that estimates and compensates the disturbance in the system in real time. The resulting control is inherently robust and easy to tune. A digital implementation of ADRC gives a temperature instability of 200 μK at one day of integration time.

  6. THE EVOLUTION OF DARK CANOPIES AROUND ACTIVE REGIONS

    SciTech Connect

    Wang, Y.-M.; Robbrecht, E.; Muglach, K. E-mail: eva.robbrecht@oma.be

    2011-05-20

    As observed in spectral lines originating from the chromosphere, transition region, and low corona, active regions are surrounded by an extensive 'circumfacular' area which is darker than the quiet Sun. We examine the properties of these dark moat- or canopy-like areas using Fe IX 17.1 nm images and line-of-sight magnetograms from the Solar Dynamics Observatory. The 17.1 nm canopies consist of fibrils (horizontal fields containing extreme-ultraviolet-absorbing chromospheric material) clumped into featherlike structures. The dark fibrils initially form a quasiradial or vortical pattern as the low-lying field lines fanning out from the emerging active region connect to surrounding network and intranetwork elements of opposite polarity. The area occupied by the 17.1 nm fibrils expands as supergranular convection causes the active-region flux to spread into the background medium; the outer boundary of the dark canopy stabilizes where the diffusing flux encounters a unipolar region of opposite sign. The dark fibrils tend to accumulate in regions of weak longitudinal field and to become rooted in mixed-polarity flux. To explain the latter observation, we note that the low-lying fibrils are more likely to interact with small loops associated with weak, opposite-polarity flux elements in close proximity, than with high loops anchored inside strong unipolar network flux. As a result, the 17.1 nm fibrils gradually become concentrated around the large-scale polarity inversion lines (PILs), where most of the mixed-polarity flux is located. Systematic flux cancellation, assisted by rotational shearing, removes the field component transverse to the PIL and causes the fibrils to coalesce into long PIL-aligned filaments.

  7. DIVERGENT HORIZONTAL SUB-SURFACE FLOWS WITHIN ACTIVE REGION 11158

    SciTech Connect

    Jain, Kiran; Tripathy, S. C.; Hill, F. E-mail: stripathy@nso.edu

    2015-07-20

    We measure the horizontal subsurface flow in a fast emerging active region (AR; NOAA 11158) using the ring-diagram technique and the Helioseismic and Magnetic Imager high spatial resolution Dopplergrams. This AR had a complex magnetic structure and displayed significant changes in morphology during its disk passage. Over a period of six days from 2011 February 11 to 16, the temporal variation in the magnitude of the 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. Furthermore, both zonal and meridional components have opposite signs for trailing and leading polarity regions at all depths showing divergent flows within the AR. We also find a sharp decrease in the magnitude of total horizontal velocity in deeper layers around major flares. It is suggested that the re-organization of magnetic fields during flares, combined with the sunspot rotation, decreases the magnitude of horizontal flows or that the flow kinetic energy has been converted into the energy released by flares. After the decline in flare activity and sunspot rotation, the flows tend to follow the pattern of magnetic activity. We also observe less variation in the velocity components near the surface but these tend to increase with depth, further demonstrating that the deeper layers are more affected by the topology of ARs.

  8. Synchronous fire activity in the tropical high Andes: an indication of regional climate forcing.

    PubMed

    Román-Cuesta, R M; Carmona-Moreno, C; Lizcano, G; New, M; Silman, M; Knoke, T; Malhi, Y; Oliveras, I; Asbjornsen, H; Vuille, M

    2014-06-01

    Global climate models suggest enhanced warming of the tropical mid and upper troposphere, with larger temperature rise rates at higher elevations. Changes in fire activity are amongst the most significant ecological consequences of rising temperatures and changing hydrological properties in mountainous ecosystems, and there is a global evidence of increased fire activity with elevation. Whilst fire research has become popular in the tropical lowlands, much less is known of the tropical high Andean region (>2000 masl, from Colombia to Bolivia). This study examines fire trends in the high Andes for three ecosystems, the Puna, the Paramo and the Yungas, for the period 1982-2006. We pose three questions: (i) is there an increased fire response with elevation? (ii) does the El Niño- Southern Oscillation control fire activity in this region? (iii) are the observed fire trends human driven (e.g., human practices and their effects on fuel build-up) or climate driven? We did not find evidence of increased fire activity with elevation but, instead, a quasicyclic and synchronous fire response in Ecuador, Peru and Bolivia, suggesting the influence of high-frequency climate forcing on fire responses on a subcontinental scale, in the high Andes. ENSO variability did not show a significant relation to fire activity for these three countries, partly because ENSO variability did not significantly relate to precipitation extremes, although it strongly did to temperature extremes. Whilst ENSO did not individually lead the observed regional fire trends, our results suggest a climate influence on fire activity, mainly through a sawtooth pattern of precipitation (increased rainfall before fire-peak seasons (t-1) followed by drought spells and unusual low temperatures (t0), which is particularly common where fire is carried by low fuel loads (e.g., grasslands and fine fuel). This climatic sawtooth appeared as the main driver of fire trends, above local human influences and fuel build

  9. Global and Regional Temperature-change Potentials for Near-term Climate Forcers

    NASA Technical Reports Server (NTRS)

    Collins, W.J.; Fry, M.M.; Yu, H.; Fuglestvedt, J. S.; Shindell, D. T.; West, J. J.

    2013-01-01

    We examine the climate effects of the emissions of near-term climate forcers (NTCFs) from 4 continental regions (East Asia, Europe, North America and South Asia) using results from the Task Force on Hemispheric Transport of Air Pollution Source-Receptor global chemical transport model simulations. We address 3 aerosol species (sulphate, particulate organic matter and black carbon) and 4 ozone precursors (methane, reactive nitrogen oxides (NOx), volatile organic compounds and carbon monoxide). We calculate the global climate metrics: global warming potentials (GWPs) and global temperature change potentials (GTPs). For the aerosols these metrics are simply time-dependent scalings of the equilibrium radiative forcings. The GTPs decrease more rapidly with time than the GWPs. The aerosol forcings and hence climate metrics have only a modest dependence on emission region. The metrics for ozone precursors include the effects on the methane lifetime. The impacts via methane are particularly important for the 20 yr GTPs. Emissions of NOx and VOCs from South Asia have GWPs and GTPs of higher magnitude than from the other Northern Hemisphere regions. The analysis is further extended by examining the temperature-change impacts in 4 latitude bands, and calculating absolute regional temperature-change potentials (ARTPs). The latitudinal pattern of the temperature response does not directly follow the pattern of the diagnosed radiative forcing. We find that temperatures in the Arctic latitudes appear to be particularly sensitive to BC emissions from South Asia. The northern mid-latitude temperature response to northern mid-latitude emissions is approximately twice as large as the global average response for aerosol emission, and about 20-30% larger than the global average for methane, VOC and CO emissions.

  10. Trends in temperature extremes over nine integrated agricultural regions in China, 1961-2011

    NASA Astrophysics Data System (ADS)

    Wu, Xushu; Wang, Zhaoli; Zhou, Xiaowen; Lai, Chengguang; Chen, Xiaohong

    2016-06-01

    By characterizing the patterns of temperature extremes over nine integrated agricultural regions (IARs) in China from 1961 to 2011, this study performed trend analyses on 16 extreme temperature indices using a high-resolution (0.5° × 0.5°) daily gridded dataset and the Mann-Kendall method. The results show that annually, at both daytime and nighttime, cold extremes significantly decreased but warm extremes significantly increased across all IARs. Overall, nighttimes tended to warm faster than daytimes. Diurnal temperature ranges (DTR) diminished, apart from the mid-northern Southwest China Region and the mid-Loess Plateau Region. Seasonally, DTR widely diminished across all IARs during the four seasons except for spring. Higher minimum daily minimum temperature (TNn) and maximum daily maximum temperature (TXx), in both summer and winter, were recorded for most IARs except for the Huang-Huai-Hai Region; in autumn, all IARs generally encountered higher TNn and TXx. In all seasons, warming was observed at daytime and nighttime but, again, nighttimes warmed faster than daytimes. The results also indicate a more rapid warming trend in Northern and Western China than in Southern and Eastern China, with accelerated warming at high elevations. The increases in TNn and TXx might cause a reduction in agriculture yield in spring over Northern China, while such negative impact might occur in Southern China during summer. In autumn and winter, however, the negative impact possibly occurred in most of the IARs. Moreover, increased TXx in the Pearl River Delta and Yangtze River Delta is possibly related to rapid local urbanization. Climatically, the general increase in temperature extremes across Chinese IARs may be induced by strengthened Northern Hemisphere Subtropical High or weakened Northern Hemisphere Polar Vortex.

  11. Development of a Measurement System for the Figure of Merit in the High-Temperature Region

    NASA Astrophysics Data System (ADS)

    Iwasaki, H.; Yamamoto, T.; Kim, H.; Nakamoto, G.

    2013-07-01

    New equipment has been developed for evaluating the figure of merit, ZT, on the basis of the Harman method in the temperature range between room temperature and 650 K. In this temperature range, the sample holder in the vacuum chamber has a different construction as compared with the sample holder constructed for the temperature range below room temperature. Several issues that need to be considered, such as compensation for the thermal radiation effect, suppression of heat leakage from the lead wires, and the setup method for the lead wires on the sample, are examined in the considered temperature region. Evaluations of ZT are successfully made for typical thermoelectric materials, (Bi,Sb)2Te3 and CeFe3CoSb12. We then demonstrate that the influence of thermal radiation between the high- and low-temperature edges of the sample induced by the Peltier effect on the estimated value of ZT is negligible at around 600 K. Furthermore, the change in the thermoelectric properties due to repetition of the thermal cycle is studied, and a typical hysteresis behavior is observed in the considered thermoelectric materials. It is revealed that heating the sample to a high temperature causes a change in its thermoelectric properties, which one must take into account for practical applications of thermoelectric materials.

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

    NASA Technical Reports Server (NTRS)

    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.

  13. Predicting body temperature and activity of adult Polyommatus icarus using neural network models under current and projected climate scenarios.

    PubMed

    Howe, P D; Bryant, S R; Shreeve, T G

    2007-10-01

    We use field observations in two geographic regions within the British Isles and regression and neural network models to examine the relationship between microhabitat use, thoracic temperatures and activity in a widespread lycaenid butterfly, Polyommatus icarus. We also make predictions for future activity under climate change scenarios. Individuals from a univoltine northern population initiated flight with significantly lower thoracic temperatures than individuals from a bivoltine southern population. Activity is dependent on body temperature and neural network models of body temperature are better at predicting body temperature than generalized linear models. Neural network models of activity with a sole input of predicted body temperature (using weather and microclimate variables) are good predictors of observed activity and were better predictors than generalized linear models. By modelling activity under climate change scenarios for 2080 we predict differences in activity in relation to both regional differences of climate change and differing body temperature requirements for activity in different populations. Under average conditions for low-emission scenarios there will be little change in the activity of individuals from central-southern Britain and a reduction in northwest Scotland from 2003 activity levels. Under high-emission scenarios, flight-dependent activity in northwest Scotland will increase the greatest, despite smaller predicted increases in temperature and decreases in cloud cover. We suggest that neural network models are an effective way of predicting future activity in changing climates for microhabitat-specialist butterflies and that regional differences in the thermoregulatory response of populations will have profound effects on how they respond to climate change.

  14. Temperature-gated thermal rectifier for active heat flow control.

    PubMed

    Zhu, Jia; Hippalgaonkar, Kedar; Shen, Sheng; Wang, Kevin; Abate, Yohannes; Lee, Sangwook; Wu, Junqiao; Yin, Xiaobo; Majumdar, Arun; Zhang, Xiang

    2014-08-13

    Active heat flow control is essential for broad applications of heating, cooling, and energy conversion. Like electronic devices developed for the control of electric power, it is very desirable to develop advanced all-thermal solid-state devices that actively control heat flow without consuming other forms of energy. Here we demonstrate temperature-gated thermal rectification using vanadium dioxide beams in which the environmental temperature actively modulates asymmetric heat flow. In this three terminal device, there are two switchable states, which can be regulated by global heating. In the "Rectifier" state, we observe up to 28% thermal rectification. In the "Resistor" state, the thermal rectification is significantly suppressed (<1%). To the best of our knowledge, this is the first demonstration of solid-state active-thermal devices with a large rectification in the Rectifier state. This temperature-gated rectifier can have substantial implications ranging from autonomous thermal management of heating and cooling systems to efficient thermal energy conversion and storage.

  15. Extreme storm activity in North Atlantic and European region

    NASA Astrophysics Data System (ADS)

    Vyazilova, N.

    2010-09-01

    The extreme storm activity study over North Atlantic and Europe includes the analyses of extreme cyclone (track number, integral cyclonic intensity) and extreme storm (track number) during winter and summer seasons in the regions: 1) 55°N-80N, 50°W-70°E; 2) 30°N-55°N, 50°W-70°E. Extreme cyclones were selected based on cyclone centre pressure (P<=970 mbar). Extreme storms were selected from extreme cyclones based on wind velocity on 925 mbar. The Bofort scala was used for this goal. Integral cyclonic intensity (for region) includes the calculation cyclone centers number and sum of MSLP anomalies in cyclone centers. The analyses based on automated cyclone tracking algorithm, 6-hourly MSLP and wind data (u and v on 925 gPa) from the NCEP/NCAR reanalyses from January 1948 to March 2010. The comparision of mean, calculated for every ten years, had shown, that in polar region extreme cyclone and storm track number, and integral cyclonic intensity gradually increases and have maximum during last years (as for summer, as for winter season). Every ten years means for summer season are more then for winter season, as for polar, as for tropical region. Means (ten years) for tropical region are significance less then for polar region.

  16. Heat flow and temperature-depth curves throughout Alaska: finding regions for future geothermal exploration

    NASA Astrophysics Data System (ADS)

    Batir, Joseph F.; Blackwell, David D.; Richards, Maria C.

    2016-06-01

    The objective of this research is to contribute to the understanding of the thermal regime of Alaska and its relationship to geology, regional tectonics, and to suggest potential sites for future geothermal energy production. New heat flow data were collected and are combined with existing published and unpublished data, although large sections of Alaska still lack data. Fault traces were implemented into the heat flow contouring as an additional gridding constraint, to incorporate both heat flow measurements and geology. New heat flow data supported the use of geologic trends in the heat flow mapping procedure, and a heat flow map of Alaska was produced with this added constraint. The multi-input contouring strategy allows production of a map with a regional interpretation of heat flow, in addition to site-specific heat flow and thermal model interpretations in areas with sufficient data density. Utilizing the new heat flow map, temperature-at-depth curves were created for example areas. Temperature-at-depth curves are calculated to 10 km depth for the areas of Anchorage, Fairbanks, Juneau, the Alaska Peninsula, Bristol Bay, and the Copper River Basin. The temperatures-at-depth predicted near the population centers of Anchorage and Juneau are relatively low, limiting the geothermal resource potential. The Fairbanks area temperature estimates are near conventional power production temperatures (150 °C) between 3.5 and 4 km. All data areas, except at Juneau, have temperatures sufficient for low temperature geothermal applications (40 °C) by 2 km. A high heat flow region exists within the Aleutian Volcanic Arc, although new data show heat flow variations from 59 to 120 mW m-2, so individual geothermal resources within the arc will be irregularly located.

  17. PATTERNS OF ACTIVITY IN A GLOBAL MODEL OF A SOLAR ACTIVE REGION

    SciTech Connect

    Bradshaw, S. J.; Viall, N. M. E-mail: Nicholeen.M.Viall@nasa.gov

    2016-04-10

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  19. ACTIVE REGION MOSS: DOPPLER SHIFTS FROM HINODE/EXTREME-ULTRAVIOLET IMAGING SPECTROMETER OBSERVATIONS

    SciTech Connect

    Tripathi, Durgesh; Mason, Helen E.; Klimchuk, James A.

    2012-07-01

    Studying the Doppler shifts and the temperature dependence of Doppler shifts in moss regions can help us understand the heating processes in the core of the active regions. In this paper, we have used an active region observation recorded by the Extreme-ultraviolet Imaging Spectrometer (EIS) on board Hinode on 2007 December 12 to measure the Doppler shifts in the moss regions. We have distinguished the moss regions from the rest of the active region by defining a low-density cutoff as derived by Tripathi et al. in 2010. We have carried out a very careful analysis of the EIS wavelength calibration based on the method described by Young et al. in 2012. For spectral lines having maximum sensitivity between log T = 5.85 and log T = 6.25 K, we find that the velocity distribution peaks at around 0 km s{sup -1} with an estimated error of 4-5 km s{sup -1}. The width of the distribution decreases with temperature. The mean of the distribution shows a blueshift which increases with increasing temperature and the distribution also shows asymmetries toward blueshift. Comparing these results with observables predicted from different coronal heating models, we find that these results are consistent with both steady and impulsive heating scenarios. However, the fact that there are a significant number of pixels showing velocity amplitudes that exceed the uncertainty of 5 km s{sup -1} is suggestive of impulsive heating. Clearly, further observational constraints are needed to distinguish between these two heating scenarios.

  20. High Temperature Evaluation of an Active Clearance Control System Concept

    NASA Technical Reports Server (NTRS)

    Taylor, Shawn C.; Steinetz, Bruce M.; Oswald, Jay J.

    2006-01-01

    A mechanically actuated blade tip clearance control concept was evaluated in a nonrotating test rig to quantify secondary seal leakage at elevated temperatures. These tests were conducted to further investigate the feasibility of actively controlling the clearance between the rotor blade tips and the surrounding shroud seal in the high pressure turbine (HPT) section of a turbine engine. The test environment simulates the state of the back side of the HPT shroud seal with pressure differentials as high as 120 psig and temperatures up to 1000 F. As expected, static secondary seal leakage decreased with increasing temperature. At 1000 F, the test rig's calculated effective clearance (at 120 psig test pressure) was 0.0003 in., well within the industry specified effective clearance goal.

  1. The regular nocturnal course of temperature in the midlatitude mesopause region according to hydroxyl airglow measurements

    NASA Astrophysics Data System (ADS)

    Perminov, V. I.; Pertsev, N. N.

    2016-09-01

    Using ground-based spectral measurements in the near-infrared range at the Zvenigorod scientific station of the Institute of Atmospheric Physics (56° N, 37° E) for 2000-2013, we obtained average nighttime changes in rotational and vibrational temperatures of hydroxyl with its emission layer localized at mesopause heights. The rotational temperature reflects the kinetic temperature of the emission layer of the atmosphere. The analysis made it possible to determine the characteristics of the first three harmonics of diurnal temperature dynamics in the mesopause region both with and without altitudinal oscillations of the OH emission layer. In both cases, the second and third harmonics are statistically significant: their amplitudes are ˜1 K and the phases of their first maxima are near 0300 and 0130 local solar time.

  2. The discrete and localized nature of the variable emission from active regions

    NASA Technical Reports Server (NTRS)

    Arndt, Martina Belz; Habbal, Shadia Rifai; Karovska, Margarita

    1994-01-01

    Using data from the Extreme Ultraviolet (EUV) Spectroheliometer on Skylab, we study the empirical characteristics of the variable emission in active regions. These simultaneous multi-wavelength observations clearly confirm that active regions consist of a complex of loops at different temperatures. The variable emission from this complex has very well-defined properties that can be quantitatively summarized as follows: (1) It is localized predominantly around the footpoints where it occurs at discrete locations. (2) The strongest variability does not necessarily coincide with the most intense emission. (3) The fraction of the area of the footpoints, (delta n)/N, that exhibits variable emission, varies by +/- 15% as a function of time, at any of the wavelengths measured. It also varies very little from footpoint to footpoint. (4) This fractional variation is temperature dependent with a maximum around 10(exp 5) K. (5) The ratio of the intensity of the variable to the average background emission, (delta I)/(bar-I), also changes with temperature. In addition, we find that these distinctive characteristics persist even when flares occur within the active region.

  3. NuSTAR X-ray observations of small flares and non-flaring active regions

    NASA Astrophysics Data System (ADS)

    Hannah, I. G.; Grefenstette, B.; Smith, D. M.; Marsh, A.; Glesener, L.; Krucker, S.; Hudson, H. S.; White, S.; Madsen, K.; Caspi, A.; Vogel, J.; Shih, A.

    2015-12-01

    We present imaging spectroscopy of the Sun with the NuSTAR hard X-ray (HXR) telescope, an astrophysics mission that uses focusing optics to directly image X-rays between ~2-80 keV. Although not optimized for solar observations, NuSTAR's high sensitivity can probe previously inaccessible X-ray emission from the Sun - crucial for searching for high temperature and non-thermal emission from "non-flaring" active regions. We present analysis of the first NuSTAR solar observations, that began in late 2014 and continued through 2015. These include using its imaging spectroscopy capabilities to derive the thermal characteristics of several "non-flaring" active regions, providing limits to the high temperature emission. We also show NuSTAR observations of several small microflares that were also observed by Hinode/XRT (in multiple thicker filters sensitive to higher temperatures) and RHESSI. This combination of three separate X-ray telescopes provides a broad observational characterization of active region heating by these very small microflares.

  4. Using singlet molecular oxygen to probe the solute and temperature dependence of liquid-like regions in/on ice.

    PubMed

    Bower, Jonathan P; Anastasio, Cort

    2013-08-01

    Liquid-like regions (LLRs) are found at the surfaces and grain boundaries of ice and as inclusions within ice. These regions contain most of the solutes in ice and can be (photo)chemically active hotspots in natural snow and ice systems. If we assume all solutes partition into LLRs as a solution freezes, freezing-point depression predicts that the concentration of a solute in LLRs is higher than its concentration in the prefrozen (or melted) solution by the freeze-concentration factor (F). Here we use singlet molecular oxygen production to explore the effects of total solute concentration ([TS]) and temperature on experimentally determined values of F. For ice above its eutectic temperature, measured values of F agree well with freezing-point depression when [TS] is above ∼1 mmol/kg; at lower [TS] values, measurements of F are lower than predicted from freezing-point depression. For ice below its eutectic temperature, the influence of freezing-point depression on F is damped; the extreme case is with Na2SO4 as the solute, where F shows essentially no agreement with freezing-point depression. In contrast, for ice containing 3 mmol/kg NaCl, measured values of F agree well with freezing-point depression over a range of temperatures, including below the eutectic. Our experiments also reveal that the photon flux in LLRs increases in the presence of salts, which has implications for ice photochemistry in the lab and, perhaps, in the environment.

  5. The effect of deforestation on the regional temperature in Northeastern China

    NASA Astrophysics Data System (ADS)

    Yu, Lingxue; Zhang, Shuwen; Tang, Junmei; Liu, Tingxiang; Bu, Kun; Yan, Fengqin; Yang, Chaobin; Yang, Jiuchun

    2015-05-01

    Land cover change, as one of the most important driving forces to climate change, has become the research focus of the global environmental change research and global land project. More researchers studied on the global influence of Land-Use and Land-Cover Change and proved that land use change occurred at different temperature zones may produce different climate effects. For example, deforestation in tropical areas would lead to higher temperatures as the decreasing of evapotranspiration caused by the reduction of roughness and the decreasing of drag coefficient and leaf area index while, in boreal areas, similar deforestation would cause lower temperature as the increasing of albedo particularly during winter with the snow cover. However, the impact of deforestation in the temperate regions on the climate still existed uncertainty and the impacts of deforestation at different humidity conditions on climate has not explored yet. From this perspective, this article used Weather Research and Forecasting model to simulate the impact of deforestation on the temperature of Northeastern China. In this study, we designed two scenarios in July and December, respectively: One was simulated without human intervention, and the second one was simulated with the current forest covers. The results showed that the temperature in both summer and winter showed a decreasing trend when the conversion of forest to farmland occurred in northeastern China. In order to further explore the humidity impacts on the temperature, we performed sample analysis on humid, sub-humid, and semi-arid regions. According to the results, the maximum variation of temperature was found in humid areas, especially in December when the temperature decreased around 4-5 °C, while the change in semi-arid and sub-humid areas is relatively small.

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

    NASA Astrophysics Data System (ADS)

    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

  7. Surface Temperature Trends in the Arctic Atlantic Region Over the Last 2,000 Years

    NASA Astrophysics Data System (ADS)

    Korhola, A.; Hanhijarvi, S.; Tingley, M.

    2013-12-01

    We introduce a new reconstruction method that uses the ordering of all pairs of proxy observations within each record to arrive at a consensus time series that best agrees with all proxy records. By considering only pairwise comparisons, this method, which we call PaiCo, facilitates the inclusion of records with differing temporal resolutions, and relaxes the assumption of linearity to the more general assumption of a monotonically increasing relationship between each proxy series and the target climate variable. We apply PaiCo to a newly assembled collection of high-quality proxy data to reconstruct the mean temperature of the Northernmost Atlantic region, which we call Arctic Atlantic, over the last 2,000 years. The Arctic Atlantic is a dynamically important region known to feature substantial temperature variability over recent millennia, and PaiCo allows for a more thorough investigation of the Arctic Atlantic regional climate as we include a diverse array of terrestrial and marine proxies with annual to multidecadal temporal resolutions. Comparisons of the PaiCo reconstruction to recent reconstructions covering larger areas indicate greater climatic variability in the Arctic Atlantic than for the Arctic as a whole. The Arctic Atlantic reconstruction features temperatures during the Roman Warm Period and Medieval Climate Anomaly that are comparable or even warmer than those of the twentieth century, and coldest temperatures in the middle of the nineteenth century, just prior to the onset of the recent warming trend.

  8. Multiscale regression model to infer historical temperatures in a central Mediterranean sub-regional area

    NASA Astrophysics Data System (ADS)

    Diodato, N.; Bellocchi, G.; Bertolin, C.; Camuffo, D.

    2010-12-01

    To reconstruct sub-regional European climate over the past centuries, several efforts have been made using historical datasets. However, only scattered information at low spatial and temporal resolution have been produced to date for the Mediterranean area. This paper has exploited, for Southern and Central Italy (Mediterranean Sub-Regional Area), an unprecedented historical dataset as an attempt to model seasonal (winter and summer) air temperatures in pre-instrumental time (back to 1500). Combining information derived from proxy documentary data and large-scale simulation, a statistical methodology in the form of multiscale-temperature regression (MTR)-model was developed to adapt larger-scale estimations to the sub-regional temperature pattern. The modelled response lacks essentially of autocorrelations among the residuals (marginal or any significance in the Durbin-Watson statistic), and agrees well with the independent data from the validation sample (Nash-Sutcliffe efficiency coefficient >0.60). The advantage of the approach is not merely increased accuracy in estimation. Rather, it relies on the ability to extract (and exploit) the right information to replicate coherent temperature series in historical times.

  9. Coronal Jets from Minifilament Eruptions in Active Regions

    NASA Technical Reports Server (NTRS)

    Martinez, Francisco; Sterling, Alphonse C.; Falconer, David A.; Moore, Ronald L.

    2016-01-01

    Solar coronal jets are transient (frequently of lifetime approx.10 min) features that shoot out from near the solar surface, become much longer than their width, and occur in all solar regions, including coronal holes, quiet Sun, and active regions (e.g., Shimojo et al. 1996, Cirtain et al. 2007). Sterling et al. (2015) and other studies found that in coronal holes and in quiet Sun the jets result when small-scale filaments, called "minifilaments" erupt onto nearby open or high-reaching field lines. Additional studies found that coronal-jet-onset locations (and hence presumably the minifilament-eruption-onset locations) coincided with locations of magnetic-flux cancelation. For active region (AR) jets however the situation is less clear. Sterling et al. (2016) studied jets in one active region over a 24-hour period; they found that some AR jets indeed resulted from minifilament eruptions, usually originating from locations of episodes of magnetic-flux cancelation. In some cases however they could not determine whether flux was emerging or canceling at the polarity inversion line from which the minifilament erupted, and for other jets of that region minifilaments were not conclusively apparent prior to jet occurrence. Here we further study AR jets, by observing them in a single AR over a one-week period, using X-ray images from Hinode/XRT and EUV/UV images from SDO/AIA, and line-of-sight magnetograms and white-light intensity-grams from SDO/HMI. We initially identified 13 prominent jets in the XRT data, and examined corresponding AIA and HMI data. For at least several of the jets, our findings are consistent with the jets resulting from minifilament eruptions, and originating from sites of magnetic-field cancelation.

  10. Locomotor Activity and Body Temperature Patterns over a Temperature Gradient in the Highveld Mole-Rat (Cryptomys hottentotus pretoriae).

    PubMed

    Haupt, Meghan; Bennett, Nigel C; Oosthuizen, Maria K

    2017-01-01

    African mole-rats are strictly subterranean mammals that live in extensive burrow systems. High humidity levels in the burrows prevent mole-rats from thermoregulating using evaporative cooling. However, the relatively stable environment of the burrows promotes moderate temperatures and small daily temperature fluctuations. Mole-rats therefore display a relatively wide range of thermoregulation abilities. Some species cannot maintain their body temperatures at a constant level, whereas others employ behavioural thermoregulation. Here we test the effect of ambient temperature on locomotor activity and body temperature, and the relationship between the two parameters, in the highveld mole-rat. We exposed mole-rats to a 12L:12D and a DD light cycle at ambient temperatures of 30°C, 25°C and 20°C while locomotor activity and body temperature were measured simultaneously. In addition, we investigated the endogenous rhythms of locomotor activity and body temperature at different ambient temperatures. Mole-rats displayed nocturnal activity at all three ambient temperatures and were most active at 20°C, but least active at 30°C. Body temperature was highest at 30°C and lowest at 20°C, and the daily cycle was highly correlated with locomotor activity. We show that the mole-rats have endogenous rhythms for both locomotor activity and body temperature. However, the endogenous body temperature rhythm appears to be less robust compared to the locomotor activity rhythm. Female mole-rats appear to be more sensitive to temperature changes than males, increased heterothermy is evident at lower ambient temperatures, whilst males show smaller variation in their body temperatures with changing ambient temperatures. Mole-rats may rely more heavily on behavioural thermoregulation as it is more energy efficient in an already challenging environment.

  11. Locomotor Activity and Body Temperature Patterns over a Temperature Gradient in the Highveld Mole-Rat (Cryptomys hottentotus pretoriae)

    PubMed Central

    Haupt, Meghan; Bennett, Nigel C.

    2017-01-01

    African mole-rats are strictly subterranean mammals that live in extensive burrow systems. High humidity levels in the burrows prevent mole-rats from thermoregulating using evaporative cooling. However, the relatively stable environment of the burrows promotes moderate temperatures and small daily temperature fluctuations. Mole-rats therefore display a relatively wide range of thermoregulation abilities. Some species cannot maintain their body temperatures at a constant level, whereas others employ behavioural thermoregulation. Here we test the effect of ambient temperature on locomotor activity and body temperature, and the relationship between the two parameters, in the highveld mole-rat. We exposed mole-rats to a 12L:12D and a DD light cycle at ambient temperatures of 30°C, 25°C and 20°C while locomotor activity and body temperature were measured simultaneously. In addition, we investigated the endogenous rhythms of locomotor activity and body temperature at different ambient temperatures. Mole-rats displayed nocturnal activity at all three ambient temperatures and were most active at 20°C, but least active at 30°C. Body temperature was highest at 30°C and lowest at 20°C, and the daily cycle was highly correlated with locomotor activity. We show that the mole-rats have endogenous rhythms for both locomotor activity and body temperature. However, the endogenous body temperature rhythm appears to be less robust compared to the locomotor activity rhythm. Female mole-rats appear to be more sensitive to temperature changes than males, increased heterothermy is evident at lower ambient temperatures, whilst males show smaller variation in their body temperatures with changing ambient temperatures. Mole-rats may rely more heavily on behavioural thermoregulation as it is more energy efficient in an already challenging environment. PMID:28072840

  12. Electric currents and coronal heating in NOAA active region 6952

    NASA Technical Reports Server (NTRS)

    Metcalf, T. R.; Canfield, R. C.; Hudson, H. S.; Mickey, D. L.; Wulser, J. -P.; Martens, P. C. H.; Tsuneta, S.

    1994-01-01

    We examine the spatial and temporal relationship between coronal structures observed with the soft X-ray telescope (SXT) on board the Yohkoh spacecraft and the vertical electric current density derived from photospheric vector magnetograms obtained using the Stokes Polarimeter at the Mees Solar Observatory. We focus on a single active region: AR 6952 which we observed on 7 days during 1991 December. For 11 independent maps of the vertical electric current density co-aligned with non-flaring X-ray images, we search for a morphological relationship between sites of high vertical current density in the photosphere and enhanced X-ray emission in the overlying corona. We find no compelling spatial or temporal correlation between the sites of vertical current and the bright X-ray structures in this active region.

  13. Evidence of active region imprints on the solar wind structure

    NASA Technical Reports Server (NTRS)

    Hick, P.; Jackson, B. V.

    1995-01-01

    A common descriptive framework for discussing the solar wind structure in the inner heliosphere uses the global magnetic field as a reference: low density, high velocity solar wind emanates from open magnetic fields, with high density, low speed solar wind flowing outward near the current sheet. In this picture, active regions, underlying closed magnetic field structures in the streamer belt, leave little or no imprint on the solar wind. We present evidence from interplanetary scintillation measurements of the 'disturbance factor' g that active regions play a role in modulating the solar wind and possibly contribute to the solar wind mass output. Hence we find that the traditional view of the solar wind, though useful in understanding many features of solar wind structure, is oversimplified and possibly neglects important aspects of solar wind dynamics

  14. Modeling the Subsurface Evolution of Active-Region Flux Tubes

    NASA Astrophysics Data System (ADS)

    Fan, Y.

    2009-12-01

    I present results from a set of 3-D spherical-shell MHD simulations of the buoyant rise of active region flux tubes in the solar interior that put new constraints on the initial twist of the subsurface tubes in order for them to emerge with tilt angles consistent with the observed Joy's law for the mean tilt of solar active regions. Due to asymmetric stretching of the Ω-shaped tube by the Coriolis force, a field strength asymmetry develops with the leading side having a greater field strength and thus being more cohesive compared to the following side. Furthermore, the magnetic flux in the leading leg shows more coherent values of local twist α ≡ JB / B2, whereas the values in the following leg show large fluctuations and are of mixed signs.

  15. Geostatistical exploration of spatial variation of summertime temperatures in the Detroit metropolitan region

    PubMed Central

    Zhang, Kai; Oswald, Evan M.; Brown, Daniel G.; Brines, Shannon J.; Gronlund, Carina J.; White-Newsome, Jalonne L.; Rood, Richard B.; O’Neill, Marie S.

    2015-01-01

    Background Because of the warming climate urban temperature patterns have been receiving increased attention. Temperature within urban areas can vary depending on land cover, meteorological and other factors. High resolution satellite data can be used to understand this intra-urban variability, although they have been primarily studied to characterize urban heat islands at a larger spatial scale. Objective This study examined whether satellite-derived impervious surface and meteorological conditions from multiple sites can improve characterization of spatial variability of temperature within an urban area. Methods Temperature was measured at 17 outdoor sites throughout the Detroit metropolitan area during the summer of 2008. Kriging and linear regression were applied to daily temperatures and secondary information, including impervious surface and distance-to-water. Performance of models in predicting measured temperatures was evaluated by cross-validation. Variograms derived from several scenarios were compared to determine whether high-resolution impervious surface information could capture fine-scale spatial structure of temperature in the study area. Results Temperatures measured at the sites were significantly different from each other, and all kriging techniques generally performed better than the two linear regression models. Impervious surface values and distance-to-water generally improved predictions slightly. Restricting models to days with lake breezes and with less cloud cover also somewhat improved the predictions. In addition, incorporating high-resolution impervious surface information into cokriging or universal kriging enhanced the ability to characterize fine-scale spatial structure of temperature. Conclusions Meteorological and satellite-derived data can better characterize spatial variability in temperature across a metropolitan region. The data sources and methods we used can be applied in epidemiological studies and public health

  16. The oasis effect and summer temperature rise in arid regions - case study in Tarim Basin

    NASA Astrophysics Data System (ADS)

    Hao, Xingming; Li, Weihong; Deng, Haijun

    2016-10-01

    This study revealed the influence of the oasis effect on summer temperatures based on MODIS Land Surface Temperature (LST) and meteorological data. The results showed that the oasis effect occurs primarily in the summer. For a single oasis, the maximum oasis cold island intensity based on LST (OCILST) was 3.82 °C and the minimum value was 2.32 °C. In terms of the annual change in OCILST, the mean value of all oases ranged from 2.47 °C to 3.56 °C from 2001 to 2013. Net radiation (Rn) can be used as a key predictor of OCILST and OCItemperature (OCI based on air temperature). On this basis, we reconstructed a long time series (1961–2014) of OCItemperature and Tbase(air temperature without the disturbance of oasis effect). Our results indicated that the reason for the increase in the observed temperatures was the significant decrease in the OCItemperature over the past 50 years. In arid regions, the data recorded in weather stations not only underestimated the mean temperature of the entire study area but also overestimated the increasing trend of the temperature. These discrepancies are due to the limitations in the spatial distribution of weather stations and the disturbance caused by the oasis effect.

  17. A process-based stream temperature modelling approach for mountain regions

    NASA Astrophysics Data System (ADS)

    MacDonald, Ryan J.; Boon, Sarah; Byrne, James M.

    2014-04-01

    Mountain streams have thermal regimes that provide critical habitat for native aquatic organisms. However, understanding stream temperature response to environmental change in mountain regions is difficult because there is typically a lack of observations. This work aims to address this issue by coupling two process-based models to simulate stream temperature in a groundwater-dominated mountain catchment, Alberta, Canada, and using a reach-scale field study for model development and verification. Results suggest that it is possible to produce spatial simulations of hydrometeorological variables needed for process-based stream temperature modelling. Simulated stream energy budget estimates compare well with results from field-based studies, and errors in stream temperature simulations (RMSE < 1.6) are similar to other modelling studies, providing confidence in the methods developed. Model sensitivity analysis demonstrates the importance of incorporating meteorological, hydrological, and geomorphological controls on stream temperature in modelling studies. This study also demonstrates the current lack of process knowledge regarding in-stream ice cover and snowmelt effects on stream temperature, both of which can contribute substantially to stream thermal regimes. Future field-based and modelling studies should consider these processes in order to fully understand stream temperature response to environmental change.

  18. The oasis effect and summer temperature rise in arid regions - case study in Tarim Basin

    PubMed Central

    Hao, Xingming; Li, Weihong; Deng, Haijun

    2016-01-01

    This study revealed the influence of the oasis effect on summer temperatures based on MODIS Land Surface Temperature (LST) and meteorological data. The results showed that the oasis effect occurs primarily in the summer. For a single oasis, the maximum oasis cold island intensity based on LST (OCILST) was 3.82 °C and the minimum value was 2.32 °C. In terms of the annual change in OCILST, the mean value of all oases ranged from 2.47 °C to 3.56 °C from 2001 to 2013. Net radiation (Rn) can be used as a key predictor of OCILST and OCItemperature (OCI based on air temperature). On this basis, we reconstructed a long time series (1961–2014) of OCItemperature and Tbase(air temperature without the disturbance of oasis effect). Our results indicated that the reason for the increase in the observed temperatures was the significant decrease in the OCItemperature over the past 50 years. In arid regions, the data recorded in weather stations not only underestimated the mean temperature of the entire study area but also overestimated the increasing trend of the temperature. These discrepancies are due to the limitations in the spatial distribution of weather stations and the disturbance caused by the oasis effect. PMID:27739500

  19. Regional Blood-Brain Barrier Responses to Central Cholinergic Activity

    DTIC Science & Technology

    1989-07-30

    regions were of particular interest because they show the largest decreases in glucose metabolism following limbic seizures ( Ben - Ari et al., 1981). It is...following seizures ( Ben - Ari et. al., 1981). The piriform cortex-amygdala also appears to be a generator of epileptiform activity in a variety of seizure...produced by PTZ. Such studies are ongoing and the results will be given in subsequent reports. 11 REFERENCES Ben - Ari , Y., D. Richie, E. Tremblay and G

  20. Multi-wavelength Observations of Microflares Near an Active Region

    NASA Astrophysics Data System (ADS)

    Bein, B.; Veronig, A.; Rybak, J.; Gömöry, P.; Berkebile-Stoiser, S.; Sütterlin, P.

    We study the multi-wavelength characteristics of a microflaring active region (AR 10898) near disc centre. The analysed data were from the 4^{th} of July 2006, and were recorded by DOT (Hα, Ca II H), RHESSI (X-rays), TRACE (EUV) and SOHO/MDI (magnetograms). The identified microflare events were studied with respect to their magnetic field configuration and their multi-wavelength time evolution.

  1. Hot Plasma from Solar Active Region Cores: a Test of AC and DC Coronal Heating Models?

    NASA Astrophysics Data System (ADS)

    Schmelz, J. T.; Asgari-Targhi, M.; Christian, G. M.; Dhaliwal, R. S.; Pathak, S.

    2015-06-01

    Direct current (DC) models of solar coronal heating invoke magnetic reconnection to convert magnetic free energy into heat, whereas alternating current (AC) models invoke wave dissipation. In both cases the energy is supplied by photospheric footpoint motions. For a given footpoint velocity amplitude, DC models predict lower average heating rates but greater temperature variability when compared to AC models. Therefore, evidence of hot plasma (T > 5 MK) in the cores of active regions could be one of the ways for current observations to distinguish between AC and DC models. We have analyzed data from the X-Ray Telescope (XRT) and the Atmospheric Imaging Assembly for 12 quiescent active region cores, all of which were observed in the XRT Be_thick channel. We did Differential Emission Measure (DEM) analysis and achieved good fits for each data set. We then artificially truncated the hot plasma of the DEM model at 5 MK and examined the resulting fits to the data. For some regions in our sample, the XRT intensities continued to be well-matched by the DEM predictions, even without the hot plasma. This truncation, however, resulted in unacceptable fits for the other regions. This result indicates that the hot plasma is present in these regions, even if the precise DEM distribution cannot be determined with the data available. We conclude that reconnection may be heating the hot plasma component of these active regions.

  2. HOT PLASMA FROM SOLAR ACTIVE REGION CORES: A TEST OF AC AND DC CORONAL HEATING MODELS?

    SciTech Connect

    Schmelz, J. T.; Christian, G. M.; Dhaliwal, R. S.; Pathak, S.; Asgari-Targhi, M.

    2015-06-20

    Direct current (DC) models of solar coronal heating invoke magnetic reconnection to convert magnetic free energy into heat, whereas alternating current (AC) models invoke wave dissipation. In both cases the energy is supplied by photospheric footpoint motions. For a given footpoint velocity amplitude, DC models predict lower average heating rates but greater temperature variability when compared to AC models. Therefore, evidence of hot plasma (T > 5 MK) in the cores of active regions could be one of the ways for current observations to distinguish between AC and DC models. We have analyzed data from the X-Ray Telescope (XRT) and the Atmospheric Imaging Assembly for 12 quiescent active region cores, all of which were observed in the XRT Be-thick channel. We did Differential Emission Measure (DEM) analysis and achieved good fits for each data set. We then artificially truncated the hot plasma of the DEM model at 5 MK and examined the resulting fits to the data. For some regions in our sample, the XRT intensities continued to be well-matched by the DEM predictions, even without the hot plasma. This truncation, however, resulted in unacceptable fits for the other regions. This result indicates that the hot plasma is present in these regions, even if the precise DEM distribution cannot be determined with the data available. We conclude that reconnection may be heating the hot plasma component of these active regions.

  3. A Survey of Nanoflare Properties in Solar Active Regions

    NASA Astrophysics Data System (ADS)

    Viall, N. M.; Klimchuk, J. A.

    2013-12-01

    We investigate coronal heating using a systematic technique to analyze the properties of nanoflares in active regions (AR). Our technique computes cooling times, or time-lags, on a pixel-by-pixel basis using data taken with the Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory. Our technique has the advantage that it allows us to analyze all of the coronal AR emission, including the so-called diffuse emission. We recently presented results using this time-lag analysis on NOAA AR 11082 (Viall & Klimchuk 2012) and found that the majority of the pixels contained cooling plasma along their line of sight, consistent with impulsive coronal nanoflare heating. Additionally, our results showed that the nanoflare energy is stronger in the AR core and weaker in the active region periphery. Are these results representative of the nanoflare properties exhibited in the majority of ARs, or is AR 11082 unique? Here we present the time-lag results for a survey of ARs and show that these nanoflare patterns are born out in other active regions, for a range of ages, magnetic complexity, and total unsigned magnetic flux. Other aspects of the nanoflare properties, however, turn out to be dependent on certain AR characteristics.

  4. The Intermediate-line Region in Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

    We show that the recently observed suppression of the gap between the broad-line region (BLR) and the narrow-line region (NLR) in some active galactic nuclei (AGNs) 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 FWHM ˜ 700-1200 km s-1. These lines are believed to be originating from an ILR located somewhere between the BLR and NLR. As 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 the cloudy photoionization code show that the differences in the shape of the spectral energy distribution from the central region of AGNs do not diminish the apparent gap in the line emission in those objects. A strong discontinuity in the line emission versus radius exists for all lines at the dust sublimation radius. However, increasing the gas density to ˜{10}11.5 cm-3 at the sublimation radius provides the continuous line emission versus radius and fully explains the recently observed lack of apparent gap in some AGNs. We show that such a high density is consistent with the density of upper layers of an accretion disk atmosphere. Therefore, the upper layers of the disk atmosphere can give rise to the formation of observed emission-line clouds.

  5. Influence of Saline on Temperature Profile of Laser Lithotripsy Activation

    PubMed Central

    Silva, Igor N.; Donalisio da Silva, Rodrigo; Gustafson, Diedra; Sehrt, David; Kim, Fernando J.

    2015-01-01

    Abstract Purpose: We established an ex vivo model to evaluate the temperature profile of the ureter during laser lithotripsy, the influence of irrigation on temperature, and thermal spread during lithotripsy with the holmium:yttrium-aluminum-garnet (Ho:YAG) laser. Materials and Methods: Two ex vivo models of Ovis aries urinary tract and human calcium oxalate calculi were used. The Open Ureteral Model was opened longitudinally to measure the thermal profile of the urothelium. On the Clinical Model, anterograde ureteroscopy was performed in an intact urinary system. Temperatures were measured on the external portion of the ureter and the urothelium during lithotripsy and intentional perforation. The lithotripsy group (n=20) was divided into irrigated (n=10) and nonirrigated (n=10), which were compared for thermal spread length and values during laser activation. The intentional perforation group (n=10) was evaluated under saline flow. The Ho:YAG laser with a 365 μm laser fiber and power at 10W was used (1J/Pulse at 10 Hz). Infrared Fluke Ti55 Thermal Imager was used for evaluation. Maximum temperature values were recorded and compared. Results: On the Clinical Model, the external ureteral wall obtained a temperature of 37.4°C±2.5° and 49.5°C±2.3° (P=0.003) and in the Open Ureteral Model, 49.7°C and 112.4°C with and without irrigation, respectively (P<0.05). The thermal spread along the external ureter wall was not statically significant with or without irrigation (P=0.065). During intentional perforation, differences in temperatures were found between groups (opened with and without irrigation): 81.8°±8.8° and 145.0°±15.0°, respectively (P<0.005). Conclusion: There is an increase in the external ureteral temperature during laser activation, but ureteral thermal values decreased when saline flow was applied. Ureter thermal spread showed no difference between irrigated and nonirrigated subgroups. This is the first laser lithotripsy thermography study

  6. The solar extreme ultra-violet corona: Resolved loops and the unresolved active region corona

    NASA Astrophysics Data System (ADS)

    Cirtain, Jonathan Wesley

    In this work, physical characteristics of the solar corona as observed in the Extreme Ultra-Violet (EUV) regime are investigated. The focus will be the regions of intense EUV radiation generally found near the locations of sunspots. These regions are commonly called active regions. Multiple space- based observing platforms have been deployed in the last decade; it is possible to use several of these observatories in combination to develop a more complete picture of the solar corona. Joint Observing Program 146 was created to collect spectroscopic intensities using the Coronal Diagnostic Spectrometer on Solar and Heliospheric Observatory and EUV images using NASA's Transition Region and Coronal Explorer. The emission line intensities are analyzed to develop an understanding of the temperature and density of the active region coronal plasma. However, the performance of the CDS instrument in the spatial and temporal domains is limited and to compensate for these limitations, data collected by the TRACE instrument provide a high spatial and temporal resolution set of observations. One of the most exciting unsolved problems in solar astrophysics is to understand why the corona maintains a temperature roughly two orders of magnitude higher than the underlying material. A detailed investigation of the coronal emission has provided constraints on models of the heating mechanism, since the temperature, density and evolution of emission rates for multiple ionic species are indicative of the mechanism(s) working to heat the corona. The corona appears to consist of multiple unresolved structures as well as resolved active region structures, called coronal loops. The purpose of the present work is to determine the characteristics of the unresolved background corona. Using the characterizations of the coronal unresolved background, results for loops after background subtraction are also presented. This work demonstrates the magnitude of the unresolved coronal emission with

  7. A regional neural network model for predicting mean daily river water temperature

    USGS Publications Warehouse

    Wagner, Tyler; DeWeber, Jefferson Tyrell

    2014-01-01

    Water temperature is a fundamental property of river habitat and often a key aspect of river resource management, but measurements to characterize thermal regimes are not available for most streams and rivers. As such, we developed an artificial neural network (ANN) ensemble model to predict mean daily water temperature in 197,402 individual stream reaches during the warm season (May–October) throughout the native range of brook trout Salvelinus fontinalis in the eastern U.S. We compared four models with different groups of predictors to determine how well water temperature could be predicted by climatic, landform, and land cover attributes, and used the median prediction from an ensemble of 100 ANNs as our final prediction for each model. The final model included air temperature, landform attributes and forested land cover and predicted mean daily water temperatures with moderate accuracy as determined by root mean squared error (RMSE) at 886 training sites with data from 1980 to 2009 (RMSE = 1.91 °C). Based on validation at 96 sites (RMSE = 1.82) and separately for data from 2010 (RMSE = 1.93), a year with relatively warmer conditions, the model was able to generalize to new stream reaches and years. The most important predictors were mean daily air temperature, prior 7 day mean air temperature, and network catchment area according to sensitivity analyses. Forest land cover at both riparian and catchment extents had relatively weak but clear negative effects. Predicted daily water temperature averaged for the month of July matched expected spatial trends with cooler temperatures in headwaters and at higher elevations and latitudes. Our ANN ensemble is unique in predicting daily temperatures throughout a large region, while other regional efforts have predicted at relatively coarse time steps. The model may prove a useful tool for predicting water temperatures in sampled and unsampled rivers under current conditions and future projections of climate

  8. Modeling of Intrinsic Josephson Junctions in High Temperature Superconductors under External Radiation in the Breakpoint Region

    NASA Astrophysics Data System (ADS)

    Shukrinov, Yu. M.; Rahmonov, I. R.; Plecenik, A.; Streltsova, O. I.; Zuev, M. I.; Ososkov, G. A.

    2016-02-01

    The current-voltage (IV) characteristics of the intrinsic Josephson junctions in high temperature superconductors under external electromagnetic radiation are calculated numerically in the parametric resonance region. We discuss a numerical method for calculation of the Shapiro step width on the amplitude of radiation. In order to accelerate computations we used parallelization by task parameter via Simple Linux Utility for Resource Management (SLURM) arrays and tested it in the case of a single junction. An analysis of the junction transitions between rotating and oscillating states in the branching region of IV-characteristics is presented.

  9. AIRS satellite observations of meridional temperature gradient over Indian summer monsoon region

    NASA Astrophysics Data System (ADS)

    Dhaka, S. K.; Gupta, A.; Panwar, V.; Bhatnagar, R.

    2011-12-01

    To investigate temperature changes in the upper troposphere over Indian region covering from Arabian Sea (AS) to Bay of Bengal (BOB), analysis is carried out during both summer (May-June-July-August) and winter (November-December-January-February) using AIRS data at a high spatial (1×1 lat long) resolution over sea and land spanned over 2005-2010. This is done to examine the similarities and differences in the meridional temperature gradient during Asian summer monsoon and winter. During May, there is an increase in temperature latitudinal from 3oN to 20oN by ~ 2.5 K in the all the years, however, temperature is decreased gradually (~ 0.15 K per deg latitude) by ~3 K during June-July-Aug (JJA). Thus, there is a contrast behavior observed in the meridional variation of temperature during May with that of JJA. The study further suggests the latitudinal change in temperature occurs due to low OLR (convection) and its northward progression during summer. Similar analysis for the winter months (NDJF) shows the existence of latitudinal variation in temperature which has an increasing tendency from 3oN to 20oN. The change in temperature is larger (~4-5K) for winter months as compared to the summer months, the apparent change is caused by the presence of monsoon during summer months (high humidity and water vapors). During winter, the variability in temperature for Nov and Dec is found larger as compared to Jan and Feb because of increased convection (low OLR) at low latitudes (3-10oN) in the former months and latter being the dry months with no convection.

  10. Combined radiation mechanism in the sun's active region no. 75 during the eclipse of 16 February, 1980

    NASA Astrophysics Data System (ADS)

    Ji, Shuchen; Zhao, Renyang; Zhou, Li; Luo, Xianhan

    1993-02-01

    A 3D distribution of the electron temperature and density based on the radio spectrum of active region No. 75 obtained from the solar eclipse observation made on February 16 1980 is calculated. The magnetic field above the active region is calculated in terms of the solar photospheric magnetic field under the assumption of a potential field. Results show that the gyro-resonance radiation is overwhelmingly dominant in the slowly varying radiation of the active region. Bremsstrahlung radiation can reach from 5 to 20 percent of the gyro-resonance.

  11. Forward modeling transient brightenings and microflares around an active region observed with Hi-C

    SciTech Connect

    Kobelski, Adam R.; McKenzie, David E.

    2014-10-20

    Small-scale flare-like brightenings around active regions are among the smallest and most fundamental of energetic transient events in the corona, providing a testbed for models of heating and active region dynamics. In a previous study, we modeled a large collection of these microflares observed with Hinode/X-Ray Telescope (XRT) using EBTEL and found that they required multiple heating events, but could not distinguish between multiple heating events on a single strand, or multiple strands each experiencing a single heating event. We present here a similar study, but with extreme-ultraviolet data of Active Region 11520 from the High Resolution Coronal Imager (Hi-C) sounding rocket. Hi-C provides an order of magnitude improvement to the spatial resolution of XRT, and a cooler temperature sensitivity, which combine to provide significant improvements to our ability to detect and model microflare activity around active regions. We have found that at the spatial resolution of Hi-C (≈0.''3), the events occur much more frequently than expected (57 events detected, only 1 or 2 expected), and are most likely made from strands of the order of 100 km wide, each of which is impulsively heated with multiple heating events. These findings tend to support bursty reconnection as the cause of the energy release responsible for the brightenings.

  12. Data-driven modeling of surface temperature anomaly and solar activity trends

    USGS Publications Warehouse

    Friedel, Michael J.

    2012-01-01

    A novel two-step modeling scheme is used to reconstruct and analyze surface temperature and solar activity data at global, hemispheric, and regional scales. First, the self-organizing map (SOM) technique is used to extend annual modern climate data from the century to millennial scale. The SOM component planes are used to identify and quantify strength of nonlinear relations among modern surface temperature anomalies (<150 years), tropical and extratropical teleconnections, and Palmer Drought Severity Indices (0–2000 years). Cross-validation of global sea and land surface temperature anomalies verifies that the SOM is an unbiased estimator with less uncertainty than the magnitude of anomalies. Second, the quantile modeling of SOM reconstructions reveal trends and periods in surface temperature anomaly and solar activity whose timing agrees with published studies. Temporal features in surface temperature anomalies, such as the Medieval Warm Period, Little Ice Age, and Modern Warming Period, appear at all spatial scales but whose magnitudes increase when moving from ocean to land, from global to regional scales, and from southern to northern regions. Some caveats that apply when interpreting these data are the high-frequency filtering of climate signals based on quantile model selection and increased uncertainty when paleoclimatic data are limited. Even so, all models find the rate and magnitude of Modern Warming Period anomalies to be greater than those during the Medieval Warm Period. Lastly, quantile trends among reconstructed equatorial Pacific temperature profiles support the recent assertion of two primary El Niño Southern Oscillation types. These results demonstrate the efficacy of this alternative modeling approach for reconstructing and interpreting scale-dependent climate variables.

  13. Temperature sensitivity of differential absorption lidar measurements of water vapor in the 720-nm region

    NASA Technical Reports Server (NTRS)

    Browell, Edward V.; Ismail, Syed; Grossmann, Benoist E.

    1991-01-01

    Recently measured properties of water vapor (H2O) absorption lines have been used in calculations to evalute the temperature sensitivity of differential absorption lidar (Dial) H2O measurements. This paper estimates the temperature sensitivity of H2O lines in the 717-733-nm region for both H2O mixing ratio and number density measurements, and discusses the influence of the H2O line ground state energies E-double-prime, the H2O absorption linewidths, the linewidth temperature dependence parameter, and the atmospheric temperature and pressure variations with altitude and location on the temperature sensitivity calculations. Line parameters and temperature sensitivity calculations for 67 H2O lines in the 720-nm band are given which can be directly used in field experiments. Water vapor lines with E-double-prime values in the 100-300/cm range were found to be optimum for Dial measurements of H2O number densities, while E-double-prime values in the 250-500/cm range were found to be optimum for H2O mixing ratio measurements.

  14. Global and regional temperature metrics under a two-basket approach

    NASA Astrophysics Data System (ADS)

    Tanaka, Katsumasa; Cherubini, Francesco

    2015-04-01

    Climate and environmental policies and assessments including the Life Cycle Assessments (LCA) commonly employ a single basket approach, in which emissions of non-CO2 components are aggregated into their CO2 equivalents through emission metrics. Such metrics entail various assumptions, which can give rise to a large difference in metric values particularly for near-term climate forcers (NTCFs) (e.g., Tanaka et al., 2013). The difficulties in equating emissions of CO2 and NTCFs led to a proposal of a two-basket approach, which allows emission conversions among species with comparable atmospheric lifetimes (e.g., Cherubini et al., 2014). Here we explore the feasibility of a two-basket approach in the context of LCA. We extract from a LCA database several representative energy-related emissions occurring at four different locations of the world and calculate their effects on the global and regional radiative forcing and temperature change. Such results are also used to derive emission metrics such as the Global Warming Potential (GWP), Global Temperature change Potential (GTP), and Regional Temperature change Potential (RTP) and we test the performance of the metrics under a two-basket framework. Computations are performed by the Aggregated Carbon Cycle, Atmospheric Chemistry, and Climate model (ACC2) (Tanaka et al., 2013) combined with results shown in Collins et al. (2013). References Cherubini, F., T. Gasser, R. M. Bright, P. Ciais and A, H. Stromman. (2014) Linearity between temperature peak and bioenergy CO2 emission rates. Nature Climate Change, 4, 983-987. Collins, W. J., M. M. Fry, H. Yu, J. S. Fuglestvedt, D. T. Shindell and J. J. West. (2013) Global and regional temperature-change potentials for near-term climate forcers. Atmospheric Chemistry and Physics, 13, 2471-2485. Tanaka, K., D. J. A. Johansson, B. C. O'Neill, and J. S. Fuglestvedt (2013) Emission metrics under the 2°C climate stabilization target. Climatic Change, 117, 933-941.

  15. Evaluation of HIFU-induced lesion region using temperature threshold and equivalent thermal dose methods

    NASA Astrophysics Data System (ADS)

    Chang, Shihui; Xue, Fanfan; Zhou, Wenzheng; Zhang, Ji; Jian, Xiqi

    2017-03-01

    Usually, numerical simulation is used to predict the acoustic filed and temperature distribution of high intensity focused ultrasound (HIFU). In this paper, the simulated lesion volumes obtained by temperature threshold (TRT) 60 °C and equivalent thermal dose (ETD) 240 min were compared with the experimental results which were obtained by animal tissue experiment in vitro. In the simulation, the calculated model was established according to the vitro tissue experiment, and the Finite Difference Time Domain (FDTD) method was used to calculate the acoustic field and temperature distribution in bovine liver by the Westervelt formula and Pennes bio-heat transfer equation, and the non-linear characteristics of the ultrasound was considered. In the experiment, the fresh bovine liver was exposed for 8s, 10s, 12s under different power conditions (150W, 170W, 190W, 210W), and the exposure was repeated 6 times under the same dose. After the exposures, the liver was sliced and photographed every 0.2mm, and the area of the lesion region in every photo was calculated. Then, every value of the areas was multiplied by 0.2mm, and summed to get the approximation volume of the lesion region. The comparison result shows that the lesion volume of the region calculated by TRT 60 °C in simulation was much closer to the lesion volume obtained in experiment, and the volume of the region above 60 °C was larger than the experimental results, but the volume deviation was not exceed 10%. The volume of the lesion region calculated by ETD 240 min was larger than that calculated by TRT 60 °C in simulation, and the volume deviations were ranged from 4.9% to 23.7%.

  16. Monitoring rice farming activities in the Mekong Delta region

    NASA Astrophysics Data System (ADS)

    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

  17. FORMATION OF CORONAL HOLES ON THE ASHES OF ACTIVE REGIONS

    SciTech Connect

    Karachik, Nina V.; Pevtsov, Alexei A.; Abramenko, Valentyna I. E-mail: apevtsov@nso.ed

    2010-05-10

    We investigate the formation of isolated non-polar coronal holes (CHs) on the remnants of decaying active regions (ARs) at the minimum/early ascending phase of sunspot activity. We follow the evolution of four bipolar ARs and measure several parameters of their magnetic fields including total flux, imbalance, and compactness. As regions decay, their leading and following polarities exhibit different dissipation rates: loose polarity tends to dissipate faster than compact polarity. As a consequence, we see a gradual increase in flux imbalance inside a dissipating bipolar region, and later a formation of a CH in place of more compact magnetic flux. Out of four cases studied in detail, two CHs had formed at the following polarity of the decaying bipolar AR, and two CHs had developed in place of the leading polarity field. All four CHs contain a significant fraction of magnetic field of their corresponding AR. Using potential field extrapolation, we show that the magnetic field lines of these CHs were closed on the polar CH at the North, which at the time of the events was in imbalance with the polar CH at the South. This topology suggests that the observed phenomenon may play an important role in transformation of toroidal magnetic field to poloidal field, which is a key step in transitioning from an old solar cycle to a new one. The timing of this observed transition may indicate the end of solar cycle 23 and the beginning of cycle 24.

  18. Regional and global sea-surface temperatures during the last interglaciation

    NASA Astrophysics Data System (ADS)

    Hoffman, Jeremy S.; Clark, Peter U.; Parnell, Andrew C.; He, Feng

    2017-01-01

    The last interglaciation (LIG, 129 to 116 thousand years ago) was the most recent time in Earth’s history when global mean sea level was substantially higher than it is at present. However, reconstructions of LIG global temperature remain uncertain, with estimates ranging from no significant difference to nearly 2°C warmer than present-day temperatures. Here we use a network of sea-surface temperature (SST) records to reconstruct spatiotemporal variability in regional and global SSTs during the LIG. Our results indicate that peak LIG global mean annual SSTs were 0.5 ± 0.3°C warmer than the climatological mean from 1870 to 1889 and indistinguishable from the 1995 to 2014 mean. LIG warming in the extratropical latitudes occurred in response to boreal insolation and the bipolar seesaw, whereas tropical SSTs were slightly cooler than the 1870 to 1889 mean in response to reduced mean annual insolation.

  19. Evidence for a 250 second brightness oscillation at 1600 A in the solar temperature minimum region

    NASA Technical Reports Server (NTRS)

    Cook, J. W.; Ewing, J. A.

    1991-01-01

    A 330 s sequence of solar images at 1600 A, where the solar flux arises predominantly from the temperature minimum continuum, obtained from a sounding rocket flight, has been studied. The statistical distributions of the periods and amplitudes which result from fitting a sine wave to each individual 5 arcsec square box within a 350 x 350 arcsec quiet-sun field were obtained. Evidence is found for 250 s oscillations in the quiet-sun brightness temperature in about 10 arcsec coherent patches, with an average amplitude of 50 K. The amplitude corresponds to an energy flux of 180,000 ergs/sq cm/s for undamped, adiabatic, propagating sound waves, which is small compared to the heating requirement in the temperature minimum region.

  20. The Temperature and Distribution of Organic Molecules in the Inner Regions of T Tauri Disks

    NASA Technical Reports Server (NTRS)

    Mandell, Avi

    2012-01-01

    "High-resolution NIR spectroscopic observations of warm molecular gas emission from young circumstellar disks allow us to constrain the temperature and composition of material in the inner planet-forming region. By combining advanced data reduction algorithms with accurate modeling of the terrestrial atmospheric spectrum and a novel double-differencing data analysis technique, we have achieved very high-contrast measurements (S/N approx. 500-1000) of molecular emission at 3 microns. In disks around low-mass stars, we have achieved the first detections of emission from HCN and C2H2 at near-infrared wavelengths from several bright T Tauri stars using the CRIRES spectrograph on the Very Large Telescope and NIRSPEC spectrograph on the Keck Telescope. We spectrally resolve the line shape, showing that the emission has both a Keplerian and non-Keplerian component as observed previously for CO emission. We used a simplified single-temperature local thermal equilibrium (LTE) slab model with a Gaussian line profile to make line identifications and determine a best-fit temperature and initial abundance ratios, and we then compared these values with constraints derived from a detailed disk radiative transfer model assuming LTE excitation but utilizing a realistic temperature and density structure. Abundance ratios from both sets of models are consistent with each other and consistent with expected values from theoretical chemical models, and analysis of the line shapes suggests that the molecular emission originates from within a narrow region in the inner disk (R < 1 AU)."

  1. A comparison of spatial interpolation methods for soil temperature over a complex topographical region

    NASA Astrophysics Data System (ADS)

    Wu, Wei; Tang, Xiao-Ping; Ma, Xue-Qing; Liu, Hong-Bin

    2016-08-01

    Soil temperature variability data provide valuable information on understanding land-surface ecosystem processes and climate change. This study developed and analyzed a spatial dataset of monthly mean soil temperature at a depth of 10 cm over a complex topographical region in southwestern China. The records were measured at 83 stations during the period of 1961-2000. Nine approaches were compared for interpolating soil temperature. The accuracy indicators were root mean square error (RMSE), modelling efficiency (ME), and coefficient of residual mass (CRM). The results indicated that thin plate spline with latitude, longitude, and elevation gave the best performance with RMSE varying between 0.425 and 0.592 °C, ME between 0.895 and 0.947, and CRM between -0.007 and 0.001. A spatial database was developed based on the best model. The dataset showed that larger seasonal changes of soil temperature were from autumn to winter over the region. The northern and eastern areas with hilly and low-middle mountains experienced larger seasonal changes.

  2. Active Region Oscillations: Results from SOHO JOP 097

    NASA Astrophysics Data System (ADS)

    O'Shea, E.; Fleck, B.; Muglach, K.; Sütterlin, P.

    2001-05-01

    We present here an analysis of data obtained in a sunspot region, using the Coronal Diagnostic Spectrometer (CDS) on SOHO. These data were obtained in the context of the Joint Observing Program (JOP) 97 which, together with CDS, included the Michelson Doppler Imaging (MDI) instrument on SOHO, the TRACE satellite and various ground based observatories, e.g. the DOT on La Palma. Using the lines of Fe XVI 335, Mg IX 368, He I 584, O III 599, Mg X 624 and O V 624 of CDS time series data were obtained in the pore and plage regions of sunspots associated with active regions AR 9166, 9166 and 9169 between September 19-29 2000. In addition to the time series datasets we also obtained 240 arcsec x 240 arcsec raster images of the sunspot regions examined. Using different time series analysis techniques we analyse the different periods of oscillation found in time series datasets and present the results here. This research is part of the European Solar Magnetometry Network supported by the EC through the TMR programme.

  3. Helioseismology of pre-emerging active regions. III. Statistical analysis

    SciTech Connect

    Barnes, G.; Leka, K. D.; Braun, D. C.; Birch, A. C.

    2014-05-01

    The subsurface properties of active regions (ARs) prior to their appearance at the solar surface may shed light on the process of AR formation. Helioseismic holography has been applied to samples taken from two populations of regions on the Sun (pre-emergence and without emergence), each sample having over 100 members, that were selected to minimize systematic bias, as described in Paper I. Paper II showed that there are statistically significant signatures in the average helioseismic properties that precede the formation of an AR. This paper describes a more detailed analysis of the samples of pre-emergence regions and regions without emergence based on discriminant analysis. The property that is best able to distinguish the populations is found to be the surface magnetic field, even a day before the emergence time. However, after accounting for the correlations between the surface field and the quantities derived from helioseismology, there is still evidence of a helioseismic precursor to AR emergence that is present for at least a day prior to emergence, although the analysis presented cannot definitively determine the subsurface properties prior to emergence due to the small sample sizes.

  4. Daily air temperature interpolated at high spatial resolution over a large mountainous region

    USGS Publications Warehouse

    Dodson, R.; Marks, D.

    1997-01-01

    Two methods are investigated for interpolating daily minimum and maximum air temperatures (Tmin and Tmax) at a 1 km spatial resolution over a large mountainous region (830 000 km2) in the U.S. Pacific Northwest. The methods were selected because of their ability to (1) account for the effect of elevation on temperature and (2) efficiently handle large volumes of data. The first method, the neutral stability algorithm (NSA), used the hydrostatic and potential temperature equations to convert measured temperatures and elevations to sea-level potential temperatures. The potential temperatures were spatially interpolated using an inverse-squared-distance algorithm and then mapped to the elevation surface of a digital elevation model (DEM). The second method, linear lapse rate adjustment (LLRA), involved the same basic procedure as the NSA, but used a constant linear lapse rate instead of the potential temperature equation. Cross-validation analyses were performed using the NSA and LLRA methods to interpolate Tmin and Tmax each day for the 1990 water year, and the methods were evaluated based on mean annual interpolation error (IE). The NSA method showed considerable bias for sites associated with vertical extrapolation. A correction based on climate station/grid cell elevation differences was developed and found to successfully remove the bias. The LLRA method was tested using 3 lapse rates, none of which produced a serious extrapolation bias. The bias-adjusted NSA and the 3 LLRA methods produced almost identical levels of accuracy (mean absolute errors between 1.2 and 1.3??C), and produced very similar temperature surfaces based on image difference statistics. In terms of accuracy, speed, and ease of implementation, LLRA was chosen as the best of the methods tested.

  5. Large-scale changes of the temperature frontal zones and regional features in heat transfer patterns based on SST data

    NASA Astrophysics Data System (ADS)

    Kartushinsky, A.; Shishkin, A.

    The intensity of heat transfer by currents influences on the location of energetically active zones in the ocean In such zones the hydrological parameter gradients increase which reveals the structure of frontal zones SST data isn t enough to determine the location of such zones In our work we calculate according to AVHRR MCSST data the temperature gradients in the ocean that show the large-scale changes of the temperature frontal zones TFZ for the 1982 -- 1986 average monthly and 1990 -- 2001 average weekly periods To study how the temperature frontal zones are connected with the regional heat patterns we use the data concerned with the space-time variability of SST gradients for separate Pacific regions In our case the focus is placed on the investigation of the connection between the formation of the El Ni v n o-Southern Oscillation South-East Pacific and the variability of the heat transfer near the shores of North-West Pacific For the investigation of the main factors influencing on the heat redistribution in the ocean and of the reasons for the large-scale changes in the TFZ structure we use a two-dimensional horizontal numerical model of heat transfer The model takes into consideration the current speed turbulent diffusion and solar radiation Besides the results were obtained concerning heat transformation in several regions of North and South Atlantic which had been caused by the large-scale changes in the TFZ structure The research results and model experiments allow to identify the time scale of the temperature field

  6. Associations between accelerated glacier mass wastage and increased summer temperature in coastal regions

    USGS Publications Warehouse

    Dyurgerov, M.; McCabe, G.J.

    2006-01-01

    Low-elevation glaciers in coastal regions of Alaska, the Canadian Arctic, individual ice caps around the Greenland ice sheet, and the Patagonia Ice Fields have an aggregate glacier area of about 332 ?? 103 km 2 and account for approximately 42% of all the glacier area outside the Greenland and Antarctic ice sheets. They have shown volume loss, especially since the end of the 1980s, increasing from about 45% in the 1960s to nearly 67% in 2003 of the total wastage from all glaciers on Earth outside those two largest ice sheets. Thus, a disproportionally large contribution of coastal glacier ablation to sea level rise is evident. We examine cumulative standardized departures (1961-2000 reference period) of glacier mass balances and air temperature data in these four coastal regions. Analyses indicate a strong association between increases in glacier volume losses and summer air temperature at regional and global scales. Increases in glacier volume losses in the coastal regions also coincide with an accelerated rate of ice discharge from outlet glaciers draining the Greenland and West Antarctic ice sheets. These processes imply further increases in sea level rise. ?? 2006 Regents of the University of Colorado.

  7. Causes of Ocean Surface temperature Changes in Atlantic andPacific Topical Cyclogenesis Regions

    SciTech Connect

    Santer, B.D.; Wigley, T.M.L.; Gleckler, P.J.; Bonfils, C.; Wehner, M.F.; AchutaRao, K.; Barnett, T.P.; Boyle, J.S.; Bruggemann, W.; Fiorino, M.; Gillett, N.; Hansen, J.E.; Jones, P.D.; Klein, S.A.; Meehl,G.A.; Raper, S.C.B.; Reynolds, R.W.; Stott, P.A.; Taylor, K.E.; Washington, W.M.

    2006-01-31

    Previous research has identified links between changes in sea surface temperature (SST) and hurricane intensity. We use climate models to study the possible causes of SST changes in Atlantic and Pacific tropical cyclogenesis regions. The observed SST increases in these regions range from 0.32 to 0.67 C over the 20th century. The 22 climate models examined here suggest that century-timescale SST changes of this magnitude cannot be explained solely by unforced variability of the climate system, even under conservative assumptions regarding the magnitude of this variability. Model simulations that include external forcing by combined anthropogenic and natural factors are generally capable of replicating observed SST changes in both tropical cyclogenesis regions.

  8. Photometric observations of the energetics of small solar active regions

    SciTech Connect

    Lawrence, J.K.; Chapman, G.A. )

    1990-10-01

    The energetics of small solar active regions was investigated using for the analysis the photometric solar images taken from July 29 to September 6, 1984 with the San Fernando Observatory's 28-cm vacuum telescope, vacuum spectroheliograph, and dual 512 element Reticon linear diode arrays. Ten small newly formed regions were observed, whose entire sunspot evolution apparently occurred within the observed disk crossing. Seven of these showed a net energy excess of a few times 10 to the 33th ergs during this time. These results are discussed in connection with the 0.1 percent decline in solar irradiance observed by the SMM/ACRIM and Nimbus 7/ERB radiometers between 1980 and 1986. 35 refs.

  9. Simultaneous SMM flat crystal spectrometer and Very Large Array observations of solar active regions

    NASA Technical Reports Server (NTRS)

    Lang, Kenneth R.; Willson, Robert F.; Smith, Kermit L.; Strong, Keith T.

    1987-01-01

    High-resolution images of the quiescent emission from two solar active regions at 20 cm (VLA) and soft X-ray (SMM FCS) wavelengths are compared. There are regions where the X-ray coronal loops have been completely imaged at 20 cm wavelength. In other regions, the X-ray radiation was detected without detectable 20 cm radiation, and vice versa. The X-ray data were used to infer average electron temperatures of about 3-million K and average electron densities of about 2.5 x 10 to the 9th/cu cm for the X-ray emitting plasma in the two active regions. The thermal bremsstrahlung of the X-ray emitting plasma is optically thin at 20 cm wavelength. The 20 cm brightness temperatures were always less than T(e), which is consistent with optically thin bremsstrahlung. The low T(B) can be explained if a higher, cooler plasma covers the hotter X-ray emitting plasma. Thermal gyroresonance radiation must account for the intense 20 cm radiation near and above sunspots where no X-ray radiation is detected.

  10. Temperature Activated Diffusion of Radicals through Ion Implanted Polymers.

    PubMed

    Wakelin, Edgar A; Davies, Michael J; Bilek, Marcela M M; McKenzie, David R

    2015-12-02

    Plasma immersion ion implantation (PIII) is a promising technique for immobilizing biomolecules on the surface of polymers. Radicals generated in a subsurface layer by PIII treatment diffuse throughout the substrate, forming covalent bonds to molecules when they reach the surface. Understanding and controlling the diffusion of radicals through this layer will enable efficient optimization of this technique. We develop a model based on site to site diffusion according to Fick's second law with temperature activation according to the Arrhenius relation. Using our model, the Arrhenius exponential prefactor (for barrierless diffusion), D0, and activation energy, EA, for a radical to diffuse from one position to another are found to be 3.11 × 10(-17) m(2) s(-1) and 0.31 eV, respectively. The model fits experimental data with a high degree of accuracy and allows for accurate prediction of radical diffusion to the surface. The model makes useful predictions for the lifetime over which the surface is sufficiently active to covalently immobilize biomolecules and it can be used to determine radical fluence during biomolecule incubation for a range of storage and incubation temperatures so facilitating selection of the most appropriate parameters.

  11. Influence of the Cardiac Myosin Hinge Region on Contractile Activity

    NASA Astrophysics Data System (ADS)

    Margossian, Sarkis S.; Krueger, John W.; Sellers, James R.; Cuda, Giovanni; Caulfield, James B.; Norton, Paul; Slayter, Henry S.

    1991-06-01

    The participation of cardiac myosin hinge in contractility was investigated by in vitro motility and ATPase assays and by measurements of sarcomere shortening. The effect on contractile activity was analyzed using an antibody directed against a 20-amino acid peptide within the hinge region of myosin. This antibody bound specifically at the hinge at a distance of 55 nm from the S1/S2 junction, was specific to human, dog, and rat cardiac myosins, did not crossreact with gizzard or skeletal myosin, and had no effect on ATPase activity of purified S1 and myofibrils. However, it completely suppressed the movement of actin filaments in in vitro motility assays and reduced active shortening of sarcomeres of skinned cardiac myocytes by half. Suppression of motion by the antihinge antibody may reflect a mechanical constraint imposed by the antibody upon the mobility of the S2 region of myosin. The results suggest that the steps in the mechanochemical energy transduction can be separately influenced through S2.

  12. Wave structures observed in the equatorial F-region plasma density and temperature during the sunset period

    NASA Astrophysics Data System (ADS)

    Savio, S.; Muralikrishna, P.; Batista, I. S.; de Meneses, F. C.

    2016-11-01

    Electron density and temperature measurements were carried out with Langmuir probes (LP) on board Brazilian sounding rockets launched soon after the local sunset from Natal (5.8°S, 35.2°W, dip 23.7°S) and Alcântara (2.3°S, 44.4°W, dip 7°S), Brazil, on December 02, 2011, and December 08, 2012, respectively. Digisondes operating near the launching sites revealed a rapid rise in the F-region base indicating a probable pre-reversal enhancement of the vertical plasma drift. Strong spread-F traces are also visible on the ionograms simultaneously recorded, suggesting the occurrence of ionospheric bubbles during these campaigns. Electron density and temperature vertical profiles estimated from the LP data exhibit in the E-F region valley (120-300 km) the presence of large-amplitude wave activity, and electron temperature values higher than 1600 K, respectively, phenomena probably related to the electrodynamic processes that occur during the sunset period.

  13. High Spatial Resolution Fe XII Observations of Solar Active Regions

    NASA Astrophysics Data System (ADS)

    Testa, Paola; De Pontieu, Bart; Hansteen, Viggo

    2016-08-01

    We use UV spectral observations of active regions with the Interface Region Imaging Spectrograph (IRIS) to investigate the properties of the coronal Fe xii 1349.4 Å emission at unprecedented high spatial resolution (˜0.33″). We find that by using appropriate observational strategies (i.e., long exposures, lossless compression), Fe xii 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 (TR; moss) Fe xii emission shows very small average Doppler redshifts ({v}{{D}} ˜ 3 km s-1) as well as modest non-thermal velocities (with an average of ˜24 km s-1 and the peak of the distribution at ˜15 km s-1). The observed distribution of Doppler shifts appears to be compatible with advanced three-dimensional radiative MHD simulations in which impulsive heating is concentrated at the TR footpoints of a hot corona. While the non-thermal broadening of Fe xii 1349.4 Å peaks at similar values as lower resolution simultaneous Hinode Extreme Ultraviolet Imaging Spectrometer (EIS) measurements of Fe xii 195 Å, IRIS observations show a previously undetected tail of increased non-thermal broadening that might be suggestive of the presence of subarcsecond heating events. We find that IRIS and EIS non-thermal line broadening measurements are affected by instrumental effects that can only be removed through careful analysis. Our results also reveal an unexplained discrepancy between observed 195.1/1349.4 Å Fe xii intensity ratios and those predicted by the CHIANTI atomic database.

  14. Boreal temperature variability inferred from maximum latewood density and tree-ring width data, Wrangell Mountain region, Alaska

    NASA Astrophysics Data System (ADS)

    Davi, Nicole K.; Jacoby, Gordon C.; Wiles, Gregory C.

    2003-11-01

    Variations in both width and density of annual rings from a network of tree chronologies were used to develop high-resolution proxies to extend the climate record in the Wrangell Mountain region of Alaska. We developed a warm-season (July-September) temperature reconstruction that spans A.D. 1593-1992 based on the first eigenvector from principal component analysis of six maximum latewood density (MXD) chronologies. The climate/tree-growth model accounts for 51% of the temperature variance from 1958 to 1992 and shows cold in the late 1600s-early 1700s followed by a warmer period, cooling in the late 1700s-early 1800s, and warming in the 20th century. The 20th century is the warmest of the past four centuries. Several severely cold warm-seasons coincide with major volcanic eruptions. The first eigenvector from a ring-width (RW) network, based on nine chronologies from the Wrangell Mountain region (A.D. 1550-1970), is correlated positively with both reconstructed and recorded Northern Hemisphere temperatures. RW shows a temporal history similar to that of MXD by increased growth (warmer) and decreased growth (cooler) intervals and trends. After around 1970 the RW series show a decrease in growth, while station data show continued warming, which may be related to increasing moisture stress or other factors. Both the temperature history based on MXD and the growth trends from the RW series are consistent with well-dated glacier fluctuations in the Wrangell Mountains and some of the temperature variations also correspond to variations in solar activity.

  15. THE EXPANSION OF ACTIVE REGIONS INTO THE EXTENDED SOLAR CORONA

    SciTech Connect

    Morgan, Huw; Jeska, Lauren; Leonard, Drew

    2013-06-01

    Advanced image processing of Large Angle and Spectrometric Coronagraph Experiment (LASCO) C2 observations reveals the expansion of the active region closed field into the extended corona. The nested closed-loop systems are large, with an apparent latitudinal extent of 50 Degree-Sign , and expanding to heights of at least 12 R{sub Sun }. The expansion speeds are {approx}10 km s{sup -1} in the AIA/SDO field of view, below {approx}20 km s{sup -1} at 2.3 R{sub Sun }, and accelerate linearly to {approx}60 km s{sup -1} at 5 R{sub Sun }. They appear with a frequency of one every {approx}3 hr over a time period of around three days. They are not coronal mass ejections (CMEs) since their gradual expansion is continuous and steady. They are also faint, with an upper limit of 3% of the brightness of background streamers. Extreme ultraviolet images reveal continuous birth and expansion of hot, bright loops from a new active region at the base of the system. The LASCO images show that the loops span a radial fan-like system of streamers, suggesting that they are not propagating within the main coronal streamer structure. The expanding loops brighten at low heights a few hours prior to a CME eruption, and the expansion process is temporarily halted as the closed field system is swept away. Closed magnetic structures from some active regions are not isolated from the extended corona and solar wind, but can expand to large heights in the form of quiescent expanding loops.

  16. Land Surface Temperature estimation using ENVISAT AATSR Data -A study over tropical deciduous forest region.

    NASA Astrophysics Data System (ADS)

    Kvs, Badarinath

    Seasonal vegetation characteristics and other related phenological parameters can be better studies by Combined analysis of reflective and thermal data recorded by coarse resolution and high repetitive satellites. ENVISAT Advanced Along Track Scanning Radiometer (AATSR) data for different seasons from January 04 to April 04 has been analyzed to derive the Normal-ized Difference Vegetation Index (NDVI) and Surface Temperature (ST) images for the forest regions of Nagarjunasagar Srisailam Tiger Reserve (NSTR), India. Temporal variation of NDVI and ST reflected the phenology of the forest area. A negative relationship was observed be-tween the NDVI and ST over all the vegetation types and the proportion of vegetation cover seemed to has bearing on the ST. Scatter plots for NDVI and ST drawn for winter season showed a good separability of land use/land cover types of the study area. AATSR operates in channels with band centers at 0.555, 0.659, 0.858,1.61,3.70,10.85 and 12m. NDVI estimated from AATSR has been taken as a parameter for estimating surface emissivity and algorithm based on nadir and forward scans of brightness temperature in 12m has been used for esti-mating surface temperature. The surface temperature(ST) showed an inverse relation with a maximum for less vegetated areas and minimum from high vegetated areas. NDVI and surface temperature are inversely related and different land use / land cover categories can be segre-gated depending on the date of satellite pass in the TS vs. NDVI relation. Combination of spectral vegetation indices and thermal infrared measurements forms a useful tool in studying the land-atmospheric interactions. The proportion of vegetation cover at pixel level plays an important role in observing surface temperature variations over forest regions. The relation between NDVI and ST depends on vegetation phenology and thus on the availability of mois-ture in forest regions. The study area comprises mostly of deciduous type of forest

  17. Using a Differential Emission Measure and Density Measurements in an Active Region Core to Test a Steady Heating Model

    NASA Astrophysics Data System (ADS)

    Winebarger, Amy R.; Schmelz, Joan T.; Warren, Harry P.; Saar, Steve H.; Kashyap, Vinay L.

    2011-10-01

    The frequency of heating events in the corona is an important constraint on the coronal heating mechanisms. Observations indicate that the intensities and velocities measured in active region cores are effectively steady, suggesting that heating events occur rapidly enough to keep high-temperature active region loops close to equilibrium. In this paper, we couple observations of active region (AR) 10955 made with the X-Ray Telescope and the EUV Imaging Spectrometer on board Hinode to test a simple steady heating model. First we calculate the differential emission measure (DEM) of the apex region of the loops in the active region core. We find the DEM to be broad and peaked around 3 MK. We then determine the densities in the corresponding footpoint regions. Using potential field extrapolations to approximate the loop lengths and the density-sensitive line ratios to infer the magnitude of the heating, we build a steady heating model for the active region core and find that we can match the general properties of the observed DEM for the temperature range of 6.3 < log T < 6.7. This model, for the first time, accounts for the base pressure, loop length, and distribution of apex temperatures of the core loops. We find that the density-sensitive spectral line intensities and the bulk of the hot emission in the active region core are consistent with steady heating. We also find, however, that the steady heating model cannot address the emission observed at lower temperatures. This emission may be due to foreground or background structures, or may indicate that the heating in the core is more complicated. Different heating scenarios must be tested to determine if they have the same level of agreement.

  18. Radiation, temperature, and vacuum effects on piezoelectric wafer active sensors

    NASA Astrophysics Data System (ADS)

    Giurgiutiu, Victor; Postolache, Cristian; Tudose, Mihai

    2016-03-01

    The effect of radiation, temperature, and vacuum (RTV) on piezoelectric wafer active sensors (PWASs) is discussed. This study is relevant for extending structural health monitoring (SHM) methods to space vehicle applications that are likely to be subjected to harsh environmental conditions such as extreme temperatures (hot and cold), cosmic radiation, and interplanetary vacuums. This study contains both theoretical and experimental investigations with the use of electromechanical impedance spectroscopy (EMIS). In the theoretical part, analytical models of circular PWAS resonators were used to derive analytical expressions for the temperature sensitivities of EMIS resonance and antiresonance behavior. Closed-form expressions for frequency and peak values at resonance and antiresonance were derived as functions of the coefficients of thermal expansion, {α }1, {α }2, {α }3; the Poisson ratio, ν and its sensitivity, \\partial ν /\\partial T; the relative compliance gradient (\\partial {s}11E/\\partial T)/{s}11E; and the Bessel function root, z and its sensitivity, \\partial z/\\partial T. In the experimental part, tests were conducted to subject the PWAS transducers to RTV conditions. In one set of experiments, several RTV exposure, cycles were applied with EMIS signatures recorded at the beginning and after each of the repeated cycles. In another set of experiments, PWAS transducers were subjected to various temperatures and the EMIS signatures were recorded at each temperature after stabilization. The processing of measured EMIS data from the first set of experiments revealed that the resonance and antiresonance frequencies changed by less than 1% due to RTV exposure, whereas the resonance and antiresonance amplitudes changed by around 15%. After processing an individual set of EMIS data from the second set of experiments, it was determined that the relative temperature sensitivity of the antiresonance frequency ({f}{{AR}}/{f}{{AR}}) is approximately 63.1× {10

  19. Measurements of Non-thermal Line Widths in Solar Active Regions

    NASA Astrophysics Data System (ADS)

    Brooks, David H.; Warren, Harry P.

    2016-03-01

    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 (1-4 MK) often found in the cores of solar active regions. This survey of 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 17.6 ± 5.3 km 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 Alfvén wave turbulence models. Furthermore, because the observed non-thermal widths are generally small, such measurements are difficult and susceptible to systematic effects.

  20. MEASUREMENTS OF NON-THERMAL LINE WIDTHS IN SOLAR ACTIVE REGIONS

    SciTech Connect

    Brooks, David H.; Warren, Harry P.

    2016-03-20

    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 (1–4 MK) often found in the cores of solar active regions. This survey of 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 17.6 ± 5.3 km s{sup −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 Alfvén wave turbulence models. Furthermore, because the observed non-thermal widths are generally small, such measurements are difficult and susceptible to systematic effects.

  1. Insolation and Resulting Surface Temperatures of the Kuiper-Rudaki Study Region on Mercury.

    NASA Astrophysics Data System (ADS)

    Bauch, Karin E.; Hiesinger, Harald; D'Amore, Mario; Helbert, Jörn; Weinauer, Julia

    2016-04-01

    The imaging spectrometer MERTIS (Mercury Radiometer and Thermal Infrared Spectrometer) is part of the payload of ESA's BepiColombo mission, which is scheduled for launch in 2017 [1]. The instrument consists of an IR-spectrometer and radiometer, which observe the surface in the wavelength range of 7-14 and 7-40μm, respectively. The four scientific objectives are to a) study Mercury's surface composition, b) identify rock-forming minerals, c) globally map the surface mineralogy and d) study surface temperature and thermal inertia [1, 2]. In preparation of the MERTIS experiment, we performed detailed thermal models of the lunar surface, which we extrapolated to Mercury. In order to calculate insolation and surface temperatures, we use a numerical model, which has been described by [7]. Surface temperatures are dependent on the surface and subsurface bulk thermophysical properties, such as bulk density, heat capacity, thermal conductivity, emissivity, topography, and albedo. Lunar and Mercurian surface temperatures show the same general characteristics. Both have very steep temperature gradients at sunrise and sunset, due to the lack of an atmosphere. However, there are major differences due to the orbital characteristics. On Mercury the 3:2 resonant rotation rate and the eccentric orbit causes local noon at longitudes 0° and 180° to coincide with perihelion, which leads to "hot poles". At longitudes 90° and 270° , local noon coincides with aphelion, which results in "cold poles" [8]. At these longitudes brief secondary sunrises and sunsets are visible, when Mercury's orbital angular velocity exceeds the spin rate during perihelion [8]. Here we present diurnal temperature curves of the Kuiper-Rudaki study region, based on thermophysical estimates and MESSENGER (Mercury Surface, Space Environment, Geochemistry, and Ranging [9]) albedo data with a resolution of 1000m/px. Our study region spans more than 90° along the equator, thus allowing us to study both, hot and

  2. Emission Measure Distribution and Heating of Two Active Region Cores

    NASA Technical Reports Server (NTRS)

    Tripathi, Durgesh; Klimchuk, James A.; Mason, Helen E.

    2011-01-01

    Using data from the Extreme-ultraviolet Imaging Spectrometer aboard Hinode, we have studied the coronal plasma in the core of two active regions. Concentrating on the area between opposite polarity moss, we found emission measure distributions having an approximate power-law form EM/T(exp 2.4) from log T = 5.55 up to a peak at log T = 6.57. The observations are explained extremely well by a simple nanoflare model. However, in the absence of additional constraints, the observations could possibly also be explained by steady heating.

  3. Hinode Observations of an Eruption from a Sigmoidal Active Region

    NASA Astrophysics Data System (ADS)

    Green, L. M.; Wallace, A. J.; Kliem, B.

    2012-08-01

    We analyse the evolution of a bipolar active region which produces an eruption during its decay phase. The soft X-ray arcade develops high shear over a time span of two days and transitions to sigmoidal shortly before the eruption. We propose that the continuous sigmoidal soft X-ray threads indicate that a flux rope has formed which is lying low in the solar atmosphere with a bald patch separatrix surface topology. The formation of the flux rope is driven by the photospheric evolution which is dominated by fragmentation of the main polarities, motion due to supergranular flows and cancellation at the polarity inversion line.

  4. SOI/MDI studies of active region seismology and evolution

    NASA Technical Reports Server (NTRS)

    Tarbell, Ted D.; Title, Alan; Hoeksema, J. Todd; Scherrer, Phil; Zweibel, Ellen

    1995-01-01

    The solar oscillations investigation (SOI) will study solar active regions using both helioseismic and conventional observation techniques. The Michelson Doppler imager (MDI) can perform Doppler continuum and line depth imagery and can produce longitudinal magnetograms, showing either the full disk or a high resolution field of view. A dynamics program of continuous full disk Doppler observations for two months per year, campaign programs of eight hours of continuous observation per day, and a synoptic magnetic program of about 15 full disk magnetograms per day, are planned. The scientific plans, measurements and observation programs, are described.

  5. Substrate-emitting semiconductor laser with a trapezoidal active region

    SciTech Connect

    Dikareva, N V; Nekorkin, S M; Karzanova, M V; Zvonkov, B N; Aleshkin, V Ya; Dubinov, A A; Afonenko, A A

    2014-04-28

    Semiconductor lasers with a narrow (∼2°) directional pattern in the planes both parallel and perpendicular to the p–n junction are fabricated. To achieve a low radiation divergence in the p–n junction plane, the active region in this plane was designed in the form of a trapezium. The narrow directional pattern in the plane perpendicular to the p–n junction was ensured by the use of a leaky mode, through which more than 90% of laser power was coupled out. (lasers)

  6. C IV Doppler shifts observed in active region filaments

    NASA Technical Reports Server (NTRS)

    Klimchuk, J. A.

    1986-01-01

    The Doppler shift properties of 21 active region filaments were studied using C IV Dopplergram data. Most are associated with corridors of weak magnetic field that separate opposite polarity strong fields seen in photospheric magnetograms. A majority of the filaments are relatively blue shifted, although several lie very close to the dividing lines between blue and red shift. Only one filament in the samples is clearly red shifted. A new calibration procedure for Dopplergrams indicates that sizable zero point offsets are often required. The center-to-limb behavior of the resulting absolute Doppler shifts suggests that filament flows are usually quite small. It is possible that they vanish.

  7. Low and room temperature photoabsorption cross sections of NH3 in the UV region

    NASA Astrophysics Data System (ADS)

    Chen, F. Z.; Judge, D. L.; Wu, C. Y. R.; Caldwell, J.

    1998-12-01

    Using synchrotron radiation as a continuum light source, we have measured the absolute absorption cross sections of NH3 with a spectral bandwidth (FWHM) of 0.5 Å. The photoabsorption cross sections of NH3 have been measured from 1750 to 2250 Å under temperature conditions of 295, 195, and 175 K. Significant temperature effects in the absorption threshold region which are mainly due to the presence of hot band absorption are observed. The cross section value at peaks and valleys for the vibrational progressions of the (0,0) to (4,0) bands vary between -80% and +40% as the temperature of NH3 changes from 295 to 175 K. In contrast to this, the changes of cross section values, Pc,T, are found to vary less than 20% for the (v', 0) vibrational progressions with v' >= 5. The measured separations between the doublet features of the (0,0), (1,0), and (2,0) bands are found to decrease as the temperature of NH3 decreases. The shifts of peak positions of Pc,T with respect to the corresponding room temperature absorption peaks show a sudden change at v' = 3 which appears to agree with the trend observed in the homogeneous line widths of the vibrational bands of NH3 ([Vaida et al., 1987]; [Ziegler, 1985]; [Ziegler, 1986]). The unusual behavior of the line widths has been attributed to the A~ state potential surface which has a dissociation barrier.

  8. The high temperature superconductivity in cuprates: physics of the pseudogap region

    NASA Astrophysics Data System (ADS)

    Cea, Paolo

    2016-08-01

    We discuss the physics of the high temperature superconductivity in hole doped copper oxide ceramics in the pseudogap region. Starting from an effective reduced Hamiltonian relevant to the dynamics of holes injected into the copper oxide layers proposed in a previous paper, we determine the superconductive condensate wavefunction. We show that the low-lying elementary condensate excitations are analogous to the rotons in superfluid 4He. We argue that the rotons-like excitations account for the specific heat anomaly at the critical temperature. We discuss and compare with experimental observations the London penetration length, the Abrikosov vortices, the upper and lower critical magnetic fields, and the critical current density. We give arguments to explain the origin of the Fermi arcs and Fermi pockets. We investigate the nodal gap in the cuprate superconductors and discuss both the doping and temperature dependence of the nodal gap. We suggest that the nodal gap is responsible for the doping dependence of the so-called nodal Fermi velocity detected in angle resolved photoemission spectroscopy studies. We discuss the thermodynamics of the nodal quasielectron liquid and their role in the low temperature specific heat. We propose that the ubiquitous presence of charge density wave in hole doped cuprate superconductors in the pseudogap region originates from instabilities of the nodal quasielectrons driven by the interaction with the planar CuO2 lattice. We investigate the doping dependence of the charge density wave gap and the competition between charge order and superconductivity. We discuss the effects of external magnetic fields on the charge density wave gap and elucidate the interplay between charge density wave and Abrikosov vortices. Finally, we examine the physics underlying quantum oscillations in the pseudogap region.

  9. Statistical downscaling and future scenario generation of temperatures for Pakistan Region

    NASA Astrophysics Data System (ADS)

    Kazmi, Dildar Hussain; Li, Jianping; Rasul, Ghulam; Tong, Jiang; Ali, Gohar; Cheema, Sohail Babar; Liu, Luliu; Gemmer, Marco; Fischer, Thomas

    2015-04-01

    Finer climate change information on spatial scale is required for impact studies than that presently provided by global or regional climate models. It is especially true for regions like South Asia with complex topography, coastal or island locations, and the areas of highly heterogeneous land-cover. To deal with the situation, an inexpensive method (statistical downscaling) has been adopted. Statistical DownScaling Model (SDSM) employed for downscaling of daily minimum and maximum temperature data of 44 national stations for base time (1961-1990) and then the future scenarios generated up to 2099. Observed as well as Predictors (product of National Oceanic and Atmospheric Administration) data were calibrated and tested on individual/multiple basis through linear regression. Future scenario was generated based on HadCM3 daily data for A2 and B2 story lines. The downscaled data has been tested, and it has shown a relatively strong relationship with the observed in comparison to ECHAM5 data. Generally, the southern half of the country is considered vulnerable in terms of increasing temperatures, but the results of this study projects that in future, the northern belt in particular would have a possible threat of increasing tendency in air temperature. Especially, the northern areas (hosting the third largest ice reserves after the Polar Regions), an important feeding source for Indus River, are projected to be vulnerable in terms of increasing temperatures. Consequently, not only the hydro-agricultural sector but also the environmental conditions in the area may be at risk, in future.

  10. Chromospheric Evolution and the Flare Activity of Super-Active Region NOAA 6555

    NASA Technical Reports Server (NTRS)

    PrasadC, Debi; Ambastha, Ashok; Srivastava, Nandita; Tripathy, Sushanta C.; Hagyard, Mona J.

    1997-01-01

    Super-active region NOAA 6555 was highly flare productive during the period March 21st - 27th, 1991 of its disk passage. We have studied its chromospheric activity using high spatial resolution H alpha filtergrams taken at Udaipur along with MSFC vector magnetograms. A possible relationship of flare productivity and the variation in shear has been explored. Flares were generally seen in those subareas of the active region which possessed closed magnetic field configuration, whereas only minor flares and/or surges occurred in subareas showing open magnetic field configuration. Physical mechanisms responsible for the observed surges are also discussed.

  11. Global and Regional Temperature-change Potentials for Near-term Climate Forcers

    NASA Technical Reports Server (NTRS)

    Collins, W.J.; Fry, M. M.; Yu, H.; Fuglestvedt, J. S.; Shindell, D. T.; West, J. J.

    2013-01-01

    The emissions of reactive gases and aerosols can affect climate through the burdens of ozone, methane and aerosols, having both cooling and warming effects. These species are generally referred to near-term climate forcers (NTCFs) or short-lived climate pollutants (SLCPs), because of their short atmospheric residence time. The mitigation of these would be attractive for both air quality and climate on a 30-year timescale, provided it is not at the expense of CO2 mitigation. In this study we examine the climate effects of the emissions of NTCFs from 4 continental regions (East Asia, Europe, North America and South Asia) using results from the Task Force on Hemispheric Transport of Air Pollution Source-Receptor global chemical transport model simulations. We address 3 aerosol species (sulphate, particulate organic matter and black carbon - BC) and 4 ozone precursors (methane, reactive nitrogen oxides - NOx, volatile organic compounds VOC, and carbon monoxide - CO). For the aerosols the global warming potentials (GWPs) and global temperature change potentials (GTPs) are simply time-dependent scaling of the equilibrium radiative forcing, with the GTPs decreasing more rapidly with time than the GWPs. While the aerosol climate metrics have only a modest dependence on emission region, emissions of NOx and VOCs from South Asia have GWPs and GTPs of higher magnitude than from the other northern hemisphere regions. On regional basis, the northern mid-latitude temperature response to northern mid-latitude emissions is approximately twice as large as the global average response for aerosol emission, and about 20-30% larger than the global average for methane, VOC and CO emissions. We also found that temperatures in the Arctic latitudes appear to be particularly sensitive to black carbon emissions from South Asia.

  12. Regional and global temperature response to anthropogenic SO2 emissions from China in three climate models

    NASA Astrophysics Data System (ADS)

    Kasoar, Matthew; Voulgarakis, Apostolos; Lamarque, Jean-François; Shindell, Drew T.; Bellouin, Nicolas; Collins, William J.; Faluvegi, Greg; Tsigaridis, Kostas

    2016-08-01

    We use the HadGEM3-GA4, CESM1, and GISS ModelE2 climate models to investigate the global and regional aerosol burden, radiative flux, and surface temperature responses to removing anthropogenic sulfur dioxide (SO2) emissions from China. We find that the models differ by up to a factor of 6 in the simulated change in aerosol optical depth (AOD) and shortwave radiative flux over China that results from reduced sulfate aerosol, leading to a large range of magnitudes in the regional and global temperature responses. Two of the three models simulate a near-ubiquitous hemispheric warming due to the regional SO2 removal, with similarities in the local and remote pattern of response, but overall with a substantially different magnitude. The third model simulates almost no significant temperature response. We attribute the discrepancies in the response to a combination of substantial differences in the chemical conversion of SO2 to sulfate, translation of sulfate mass into AOD, cloud radiative interactions, and differences in the radiative forcing efficiency of sulfate aerosol in the models. The model with the strongest response (HadGEM3-GA4) compares best with observations of AOD regionally, however the other two models compare similarly (albeit poorly) and still disagree substantially in their simulated climate response, indicating that total AOD observations are far from sufficient to determine which model response is more plausible. Our results highlight that there remains a large uncertainty in the representation of both aerosol chemistry as well as direct and indirect aerosol radiative effects in current climate models, and reinforces that caution must be applied when interpreting the results of modelling studies of aerosol influences on climate. Model studies that implicate aerosols in climate responses should ideally explore a range of radiative forcing strengths representative of this uncertainty, in addition to thoroughly evaluating the models used against

  13. Tropical temperature variability and Kelvin-wave activity in the UTLS from GPS RO measurements

    NASA Astrophysics Data System (ADS)

    Scherllin-Pirscher, Barbara; Randel, William J.; Kim, Joowan

    2017-01-01

    Tropical temperature variability over 10-30 km and associated Kelvin-wave activity are investigated using GPS radio occultation (RO) data from January 2002 to December 2014. RO data are a powerful tool for quantifying tropical temperature oscillations with short vertical wavelengths due to their high vertical resolution and high accuracy and precision. Gridded temperatures from GPS RO show the strongest variability in the tropical tropopause region (on average 3 K2). Large-scale zonal variability is dominated by transient sub-seasonal waves (2 K2), and about half of sub-seasonal variance is explained by eastward-traveling Kelvin waves with periods of 4 to 30 days (1 K2). Quasi-stationary waves associated with the annual cycle and interannual variability contribute about a third (1 K2) to total resolved zonal variance. Sub-seasonal waves, including Kelvin waves, are highly transient in time. Above 20 km, Kelvin waves are strongly modulated by the quasi-biennial oscillation (QBO) in stratospheric zonal winds, with enhanced wave activity during the westerly shear phase of the QBO. In the tropical tropopause region, however, peaks of Kelvin-wave activity are irregularly distributed in time. Several peaks coincide with maxima of zonal variance in tropospheric deep convection, but other episodes are not evidently related. Further investigations of convective forcing and atmospheric background conditions are needed to better understand variability near the tropopause.

  14. Global and regional temperature-change potentials for near-term climate forcers

    NASA Astrophysics Data System (ADS)

    Collins, W. J.; Fry, M. M.; Yu, H.; Fuglestvedt, J. S.; Shindell, D. T.; West, J. J.

    2012-09-01

    We examine the climate effects of the emissions of near-term climate forcers (NTCFs) from 4 continental regions (East Asia, Europe, North America and South Asia) using radiative forcing from the task force on hemispheric transport of air pollution source-receptor global chemical transport model simulations. These simulations model the transport of 3 aerosol species (sulphate, particulate organic matter and black carbon) and 4 ozone precursors (methane, nitric oxides (NOx), volatile organic compounds and carbon monoxide). From the equilibrium radiative forcing results we calculate global climate metrics, global warming potentials (GWPs) and global temperature change potentials (GTPs) and show how these depend on emission region, and can vary as functions of time. For the aerosol species, the GWP(100) values are -37±12, -46±20, and 350±200 for SO2, POM and BC respectively for the direct effects only. The corresponding GTP(100) values are -5.2±2.4, -6.5±3.5, and 50±33. This analysis is further extended by examining the temperature-change impacts in 4 latitude bands. This shows that the latitudinal pattern of the temperature response to emissions of the NTCFs does not directly follow the pattern of the diagnosed radiative forcing. For instance temperatures in the Arctic latitudes are particularly sensitive to NTCF emissions in the northern mid-latitudes. At the 100-yr time horizon the ARTPs show NOx emissions can have a warming effect in the northern mid and high latitudes, but cooling in the tropics and Southern Hemisphere. The northern mid-latitude temperature response to northern mid-latitude emissions of most NTCFs is approximately twice as large as would be implied by the global average.

  15. Emission Measure Distribution for an Active Region Using Coordinated SERTS and YOHKOH SXT Observations

    NASA Astrophysics Data System (ADS)

    Schmelz, J. T.; Saba, J. L. R.; Strong, K. T.; Winter, H. D.; Brosius, J. W.

    1999-09-01

    Often the derived temperature of an active region reflects the method and the nature of the instrument used in its measurement. The emission measure (i.e., the amount of emitting material) derived from spectroscopic observations usually depends on assumptions about the absolute elemental abundances and ionization fractions of the emitting ions. Yet establishing the distribution of emission measure with temperature is the first step needed to proceed with most of the interesting physics of active regions--including heating processes, cooling timescales, and loop stability. Accurately characterizing the thermal distribution of the coronal plasma requires data which can resolve multithermal features and constrain both low- and high-temperature emission. To model the temperature distribution of NOAA Active Region 7563, we have combined broadband filter data from the Yohkoh Soft X-Ray Telescope (SXT) with simultaneous spectral line data from the Goddard Solar EUV Rocket Telescope and Spectrograph (SERTS) taken during its flight on 1993 August 17. We have used a forward-folding technique to determine the emission measure distribution of the active region loops. We have found that (1) the SXT response functions are sensitive to both the elemental abundances and the ionization fractions assumed to compute the solar spectrum that is folded through the instrument effective area; (2) the relative calibration between the SERTS and the SXT instruments must be adjusted by a factor of 2 (a value consistent with the absolute measurement uncertainty of the 1993 SERTS flight) no matter which abundances or iron ionization fractions are used; (3) the two-peaked differential emission measure previously determined using SERTS data alone is not consistent with the SXT data: including the SXT data as a high-temperature constraint in the analysis requires that the emission above about 3 MK drop off steeply rather than extending out to 6 MK. The sensitivity of the SXT filter response

  16. Radio-derived three-dimensional structure of a solar active region

    NASA Astrophysics Data System (ADS)

    Tun, Samuel D.

    Solar active regions are the source of the most violent events observed on the Sun, some of which have a direct impact to modern civilization. Efforts to understand and predict such events require determination of the three-dimensional distributions of density, temperature, and magnetic fields above such active regions. This thesis presents the structure of the solar atmosphere above active region AR 10923, observed on 2006 Nov 10, as deduced from multi-wavelength studies including combined microwave observations from the Very Large Array (VLA) and the Owens Valley Solar Array (OVSA). The VLA observations provide excellent image quality at a few widely spaced frequencies while the OVSA data provide information at many intermediate frequencies to fill in the spectral coverage. In order to optimize the OVSA data for spectroscopic studies, the L1 method of self-calibration was implemented at this observatory, producing the best single frequency maps produced to date. Images at the 25 distinct, available frequencies are used to provide spatially resolved spectra along many lines of sight in the active region, from which microwave spectral diagnostics are obtained for deducing two-dimensional maps of temperature, magnetic field strength, and column density. The derived quantities are compared with multi-wavelength observations from SoHO and Hinode spacecraft, and with a standard potential magnetic field extrapolation. It is found that a two component temperature model is required to fit the data, in which a hot (> 2 MK) lower corona above the strong-field plage and sunspot regions (emitting via the gyroresonance process) is overlaid with somewhat cooler (˜ 1 MK) coronal loops that partially absorb the gyroresonance emission through the free-free (Bremsstrahlung) process. It is also found that the potential magnetic field extrapolation model can quantitatively account for the observed gyroresonance emission over most of the active region, but in a few areas a higher

  17. Temperature rise during photo-activated disinfection of root canals.

    PubMed

    Dickers, B; Lamard, L; Peremans, A; Geerts, S; Lamy, M; Limme, M; Rompen, E; De Moor, R J G; Mahler, P; Rocca, J P; Nammour, S

    2009-01-01

    The aim of this study was to determine whether it is safe to use photo-activated disinfection (PAD) during root canal treatment without heating the periodontal tissues. Root canals of 30 freshly extracted single-rooted teeth were prepared using ProFiles up to size ISO 40 and then filled with photo-sensitiser: tolonium blue (1.2 mg/l). The 635 nm diode laser was used with the manufacturer's endo-tip. Samples were irradiated for 150 s (output power 100 mW, approximate energy density 106.16 J/cm(2)). Temperatures were recorded at working length on the external root surface. After 150 s of PAD irradiation, the average temperature rise was 0.16 +/- 0.08 degrees C. All values were lower than the 7 degrees C safety level for periodontal injury. It was concluded that, regarding the temperature increase, the use of PAD in root canals could be considered harmless for periodontal tissues.

  18. Regional climate projections for the MENA-CORDEX domain: analysis of projected temperature and precipitation changes

    NASA Astrophysics Data System (ADS)

    Hänsler, Andreas; Weber, Torsten; Eggert, Bastian; Saeed, Fahad; Jacob, Daniela

    2014-05-01

    Within the CORDEX initiative a multi-model suite of regionalized climate change information will be made available for several regions of the world. The German Climate Service Center (CSC) is taking part in this initiative by applying the regional climate model REMO to downscale global climate projections of different coupled general circulation models (GCMs) for several CORDEX domains. Also for the MENA-CORDEX domain, a set of regional climate change projections has been established at the CSC by downscaling CMIP5 projections of the Max-Planck-Institute Earth System Model (MPI-ESM) for the scenarios RCP4.5 and RCP8.5 with the regional model REMO for the time period from 1950 to 2100 to a horizontal resolution of 0.44 degree. In this study we investigate projected changes in future climate conditions over the domain towards the end of the 21st century. Focus in the analysis is given to projected changes in the temperature and rainfall characteristics and their differences for the two scenarios will be highlighted.

  19. The morphology of flare phenomena, magnetic fields, and electric currents in active regions. II - NOAA active region 5747 (1989 October)

    NASA Technical Reports Server (NTRS)

    Leka, K. D.; Canfield, Richard C.; Mcclymont, A. N.; De La Beaujardiere, J.-F.; Fan, Yuhong; Tang, F.

    1993-01-01

    The paper describes October 1989 observations in NOAA Active Region 5747 of the morphology of energetic electron precipitation and high-pressure coronal flare plasmas of three flares and their relation to the vector magnetic field and vertical electric currents. The H-alpha spectroheliograms were coaligned with the vector magnetograms using continuum images of sunspots, enabling positional accuracy of a few arcsec. It was found that, during the gradual phase, the regions of the H-alpha flare that show the effects of enhanced pressure in the overlying corona often encompass extrema of the vertical current density, consistent with earlier work showing a close relationship between H-alpha emission and line-of-sight currents. The data are also consistent with the overall morphology and evolution described by erupting-filament models such as those of Kopp and Pneuman (1976) and Sturrock (1989).

  20. Behaviour of oscillations in loop structures above active regions

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    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 171 Å 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 is close to 40° above the umbra boundaries in the transition region.

  1. Active Region Magnetic Structure Observed in the Photosphere and Chromosphere

    NASA Technical Reports Server (NTRS)

    Leka, K. D.; Metcalf, Thomas R.

    2001-01-01

    The magnetic flux above sunspots and plage in NOAA (National Oceanic and Atmospheric Administration) Active Region 8299 has been measured in the photosphere and the chromosphere. We investigate the vertical magnetic structure above the umbrae, penumbrae and plage regions using quantitative statistical comparisons of the photospheric and chromospheric vector magnetic flux data. The results include: (1) a decrease in flux with height, (2) the direct detection of the superpenumbral canopy in the chromosphere, (3) values for dB/dz which are consistent with earlier investigations when derived from a straight difference between the two datasets but quite low when derived from the delta x B = 0 condition, (4) a monolithic structure in the umbra which extends well into the upper chromosphere with a very complex and varied structure in the penumbra and plage, as evidenced by (5) a uniform magnetic scale height in the umbrae with an abrupt jump to widely varying scale heights in the penumbral and plage regions. Further, we find (6) evidence for a very large (delta z approximately equals 3Mm) height difference between the atmospheric layers sampled in the two magnetograms, almost a factor of three larger than that implied by atmospheric models. We additionally test the apropriateness of using photospheric magnetic flux as a boundary for field-line extrapolations, and find a better agreement with observed coronal structure when the chromospheric flux is used as a boundary.

  2. Photospheric electric current and transition region brightness within an active region

    NASA Technical Reports Server (NTRS)

    Deloach, A. C.; Hagyard, M. J.; Rabin, D.; Moore, R. L.; Smith, B. J., Jr.; West, E. A.; Tandberg-Hanssen, E.

    1984-01-01

    Distributions of vertical electrical current density J(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 April 6 and 7, 1980 with the Marshall Space Flight Center vector magnetograph; ultraviolet wavelength spectroheliograms (L-alpha and N V 1239 A) were obtained with the UV Spectrometer and Polarimeter experiment aboard the Solar Maximum Mission satellite. Spatial registration of the J(z) (5 arcsec resolution) and UV (3 arcsec 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. It is concluded that, although resistive heating may be important in the transition region, the currents responsible for the heating are largely unresolved in the present measurements and have no simple correlation with the residual current measured on 5-arcsec scales.

  3. Coronal temperatures, heating, and energy flow in a polar region of the sun at solar maximum

    NASA Technical Reports Server (NTRS)

    Withbroe, G. L.; Kohl, J. L.; Weiser, H.; Munro, R. H.

    1985-01-01

    The profiles of resonantly scattered Lyman-alpha coronal radiation have been used to determine the hydrogen kinetic temperature from 1.5 to 4 solar radius from the center of the polar region of the corona observed in 1980 at solar maximum. Hydrogen temperatures derived from the line profiles were found to decrease with height from 1.2 million K at r = 1.5 solar radii to 600,000 K at r = 4 solar radius. Comparison of the measured kinetic temperatures with predictions from a semiempirical two-fluid model showed evidence of a small amount of heating or a nonthermal contribution to the motions of coronal protons between 1.5 and 4 solar radius. The widths of the profiles confirmed an upper limit of 110 + or - 15 km/s on the rms magnitude of the line-of-sight component of velocities between 1.5 and 4 solar radius. Density measurements obtained in situ in the solar wind in the ecliptic were used to locate the sources of low speed and high-speed winds in the polar region. An eclipse photograph of the corona at solar maximum is provided.

  4. Coronal temperatures, heating, and energy flow in a polar region of the sun at solar maximum

    SciTech Connect

    Withbroe, G.L.; Kohl, J.L.; Weiser, H.; Munro, R.H.

    1985-10-01

    The profiles of resonantly scattered Lyman-alpha coronal radiation have been used to determine the hydrogen kinetic temperature from 1.5 to 4 solar radius from the center of the polar region of the corona observed in 1980 at solar maximum. Hydrogen temperatures derived from the line profiles were found to decrease with height from 1.2 million K at r = 1.5 solar radii to 600,000 K at r = 4 solar radius. Comparison of the measured kinetic temperatures with predictions from a semiempirical two-fluid model showed evidence of a small amount of heating or a nonthermal contribution to the motions of coronal protons between 1.5 and 4 solar radius. The widths of the profiles confirmed an upper limit of 110 + or - 15 km/s on the rms magnitude of the line-of-sight component of velocities between 1.5 and 4 solar radius. Density measurements obtained in situ in the solar wind in the ecliptic were used to locate the sources of low speed and high-speed winds in the polar region. An eclipse photograph of the corona at solar maximum is provided. 31 references.

  5. Rising air and stream-water temperatures in Chesapeake Bay region, USA

    USGS Publications Warehouse

    Rice, Karen C.; Jastram, John D.

    2015-01-01

    Monthly mean air temperature (AT) at 85 sites and instantaneous stream-water temperature (WT) at 129 sites for 1960–2010 are examined for the mid-Atlantic region, USA. Temperature anomalies for two periods, 1961–1985 and 1985–2010, relative to the climate normal period of 1971–2000, indicate that the latter period was statistically significantly warmer than the former for both mean AT and WT. Statistically significant temporal trends across the region of 0.023 °C per year for AT and 0.028 °C per year for WT are detected using simple linear regression. Sensitivity analyses show that the irregularly sampled WT data are appropriate for trend analyses, resulting in conservative estimates of trend magnitude. Relations between 190 landscape factors and significant trends in AT-WT relations are examined using principal components analysis. Measures of major dams and deciduous forest are correlated with WT increasing slower than AT, whereas agriculture in the absence of major dams is correlated with WT increasing faster than AT. Increasing WT trends are detected despite increasing trends in streamflow in the northern part of the study area. Continued warming of contributing streams to Chesapeake Bay likely will result in shifts in distributions of aquatic biota and contribute to worsened eutrophic conditions in the bay and its estuaries.

  6. Transient temperature rise in a mouse due to low-frequency regional hyperthermia

    NASA Astrophysics Data System (ADS)

    Trakic, Adnan; Liu, Feng; Crozier, Stuart

    2006-04-01

    A refined nonlinear heat transfer model of a mouse has been developed to simulate the transient temperature rise in a neoplastic tumour and neighbouring tissue during regional hyperthermia using a 150 kHz inductive coil. In this study, we incorporate various bio-energetic enhancements to the heat transfer equation and numerical validations based on experimental findings for the mouse, in terms of nonlinear metabolic heat production, homeothermy, blood perfusion parameters, thermoregulation, psychological and physiological effects. The discretized bio-heat transfer equation has been validated with the commercial software FEMLAB on a canonical multi-sphere object before applying the scheme to the inhomogeneous mouse voxel phantom. The time-dependent numerical results of regional hyperthermia of mouse thigh have been compared with the available experimental temperature results with only a few small disparities. During the first 20 min of local unfocused heating, the temperature in the tumour and the surrounding tissue increased by around 7.5 °C. The objective of this preliminary study was to develop a validated electrothermal numerical scheme for inductive hyperthermia of a small mammal with the intention of expanding the model into a complete numerical solution involving ferromagnetic nanoparticles for targeted heating of tumours at low frequencies. In addition, the numerical scheme herein could assist in optimizing and tailoring of focused electromagnetic fields for hyperthermia.

  7. Evaluation of Multiple Regional Climate Models for Summer Extremes of Temperature and Precipitation over East Asia

    NASA Astrophysics Data System (ADS)

    Park, Changyong; Min, Seung-Ki

    2014-05-01

    The regional climate models (RCMs) have been widely used to generate more detailed information in space and time of climate patterns produced by the global climate models (GCMs). Recently the international collaborative effort has been set up as the CORDEX (Coordinated Regional Climate Downscaling Experiment) project which covers several regional domains including East Asia. In this study, five RCMs (HadGEM3-RA, RegCM4, SNU-MM5, SNU-WRF, and YSU-RSM) participating in the CORDEX-East Asia project are evaluated in terms of their skills at simulating climatology of summer extremes. We examine bias and RMSE and conduct a Taylor diagram analysis using seasonal maxima of daily mean temperature and daily precipitation amount over the East Asia land area from 'historical' experiments of individual RCMs and their multi-model ensemble means (MME). The APHRODITE (Asian Precipitation-Highly-Resolved Observational Data Integration Toward Evaluation) datasets on 0.5° x 0.5° grids are used as observations. Results show similar systematic bias patterns between seasonal means and extremes. A cold bias is found along the coast while a warm bias occurs in the northern China. Overall wet bias appears in East Asia but there is a substantial dry bias in South Korea. This dry bias appears related to be a cold SST (sea surface temperature) around South Korea, positioning the monsoonal front (Changma) further south than observations. Taylor diagram analyses show that temperature has better skill in means than in extremes because of higher spatial correlation whereas precipitation exhibits better skill in extremes than in means due to better spatial variability. The latter implies that extreme rainfall events may be better captured although seasonal mean precipitation tends to be overestimated by RCMs. The model performances between mean and extreme are found to be closely related, but not clearly between temperature and precipitation. Temperatures are always better simulated than

  8. THE MAGNETIC CLASSIFICATION OF SOLAR ACTIVE REGIONS 1992–2015

    SciTech Connect

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

    2016-03-20

    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.

  9. Multi-Wavelength Study of Active Region Loop Dynamics

    NASA Astrophysics Data System (ADS)

    Banerjee, D.

    2006-11-01

    Observations have revealed the existence of weak transient disturbances in extended coronal loop systems. These propagating disturbances (PDs) originate from small scale brightenings at the footpoints of the loops and propagate upward along the loops. In all cases observed, the projected propagation speed is close to, but below the expected sound speed in the loops. This suggests that the PDs could be interpreted as slow mode MHD waves. Interpreting the oscillation in terms of different wave modes and/or plasma motions always depend on the line of sight as we observe in the limb or on the center of the disk. The JOP 165 campaign will address some of these questions. MDI and TRACE photospheric and UV imaging of TRACE and SPIRIT have been acquired simultaneously with high temporal and spatial coverage along with the spectroscopic data from CDS. EIT was operated in the shutter-less mode to achieve high Cadence. Some of the off- limb active region dynamics and oscillations observed during this JOP campaign will be focused in this presentation. Plasma condensations and temporal variations in active region loops will be also addressed.

  10. Magnetic field measurements in and above a limb active region

    NASA Astrophysics Data System (ADS)

    Philip, Judge

    2013-07-01

    We analyze spectropolarimetric data of a limb active region (NOAA 11302) obtained on September 22nd 2011 using the Facility Infrared Spectrometer (FIRS) at the Dunn Solar Telescope (DST). Stokes profiles including lines of Si I 1028.7 nm and He I 1083 nm were obtained in three scans over a 45"x75" area. Simultaneous narrow band Ca II K and G-band intensity data were acquired with a cadence of 5s at the DST. The He I data show not only typical active region polarization signatures, but also signatures in plumes -- cool post flare loops -- which extend many Mm into the corona across the visible limb. The plumes have remarkably uniform brightness, and the plume plasma is significantly Doppler shifted as it drains from the corona. Using carefully constructed observing and calibration sequences and applying Principal Component Analysis to remove instrumental artifacts, we achieved a polarization sensitivity approaching 0.02%. With this sensitivity we attempt to diagnose the vector magnetic fields and plasma properties of chromospheric and cool coronal material in and above NOAA 11302. Inversions using various radiative transfer models in the HAZEL code are remarkably consistent with the idea that plume spectra are formed in a simple, slab-like geometry, but that the ``disk'' spectra are formed under more traditional models (Milne-Eddington). The inverted magnetic data of He I lines are compared with photospheric inversions of DST Si I and Fe I data from the Solar Dynamics Observatory.

  11. Material Supply and Magnetic Configuration of an Active Region Filament

    NASA Astrophysics Data System (ADS)

    Zou, P.; Fang, C.; Chen, P. F.; Yang, K.; Hao, Q.; Cao, Wenda

    2016-11-01

    It is important to study the fine structures of solar filaments with high-resolution observations, since it can help us understand the magnetic and thermal structures of the filaments and their dynamics. In this paper, we study a newly formed filament located inside the active region NOAA 11762, which was observed by the 1.6 m New Solar Telescope at Big Bear Solar Observatory from 16:40:19 UT to 17:07:58 UT on 2013 June 5. As revealed by the Hα filtergrams, cool material is seen to be injected into the filament spine with a speed of 5-10 km s-1. At the source of the injection, brightenings are identified in the chromosphere, which are accompanied by magnetic cancellation in the photosphere, implying the importance of magnetic reconnection in replenishing the filament with plasmas from the lower atmosphere. Counter-streamings are detected near one endpoint of the filament, with the plane-of-the-sky speed being 7-9 km s-1 in the Hα red-wing filtergrams and 9-25 km s-1 in the blue-wing filtergrams. The observations are indicative that this active region filament is supported by a sheared arcade without magnetic dips, and the counter-streamings are due to unidirectional flows with alternative directions, rather than due to the longitudinal oscillations of filament threads as in many other filaments.

  12. Lithologic descriptions and temperature profiles of five wells in the southwestern Valles caldera region, New Mexico

    SciTech Connect

    Shevenell, L.; Goff, F.; Miles, D.; Waibel, A.; Swanberg, C.

    1988-01-01

    The subsurface stratigraphy and temperature profiles of the southern and western Valles caldera region have been well constrained with the use of data from the VC-1, AET-4, WC 23-4, PC-1 and PC-2 wells. Data from these wells indicate that thermal gradients west of the caldera margin are between 110 and 140)degrees)C/km, with a maximum gradient occurring in the bottom of PC-1 equal to 240)degrees)C/km as a result of thermal fluid flow. Gradients within the caldera reach a maximum of 350)degrees)C/km, while the maximum thermal gradient measured southwest of the caldera in the thermal outflow plume is 140)degrees)C/km. The five wells exhibit high thermal gradients (>60)deghrees)C/km) resulting from high conductive heat flow associated with the Rio Grande rift and volcanism in the Valles caldera, as well as high convective heat flow associated with circulating geothermal fluids. Gamma logs run in four of the five wells appear to be of limited use for stratigraphic correlations in the caldera region. However, stratigraphic and temperature data from the five wells provide information about the structure and thermal regime of the southern and western Valles caldera region. 29 refs., 9 figs. 2 tabs.

  13. Homogeneous temperature and precipitation series for a Peruvian High Andes regions from 1965 to 2009

    NASA Astrophysics Data System (ADS)

    Acuña, D.; Serpa Lopez, B.; Silvestre, E.; Konzelmann, Th.; Rohrer, M.; Schwarb, M.; Salzmann, N.

    2010-09-01

    As a basis of a joint Swiss-Peruvian effort focused on water resources, food security and disaster preparedness (Peruvian Climate Adaptation Project, PACC) clean and homogenized meteorological datasets have been elaborated for the Cusco and Apurimac Regions in the Central Andes. Operational and historical data series of more than 100 stations of the Peruvian Meteorological and Hydrological Service (SENAMHI) were available as a data base. Additionally, meteorological data provided by the National Climatic Data Centre (NCDC) or the Meteorological Aerodrome Records (METAR), have been considered. In contrast to many European countries, where most conventional sensors have been replaced by automated sensors during the last decades, instrumentation of climatological stations remained unchanged in Peru. Station records and station history of the Cusco-Apurimac-region are partially fragmentary or lost, mainly because of armed conflicts, particularly in the 1980ies. Moreover, many stations do observe precipitation as only variable. As a consequence, it was only possible so far to elaborate four complete homogenized air temperature series (Curahuasi 2763m a.s.l., Granja Kcayra-Cusco 3219m, Sicuani, 3574m and La Angostura, 4150m) since 1965. For precipitation a larger number of stations was available for elaboration, which is important because of the small scaled characteristics of the mostly convective type precipitation events in these regions. Based on these homogenized series, linear and gaussian low pass filtered trends have been calculated for all series of precipitation and air temperature records.

  14. Determination of regional brain temperature using proton magnetic resonance spectroscopy to assess brain-body temperature differences in healthy human subjects.

    PubMed

    Childs, Charmaine; Hiltunen, Yrjö; Vidyasagar, Rishma; Kauppinen, Risto A

    2007-01-01

    Proton magnetic resonance spectroscopy ((1)H MRS) was used to determine brain temperature in healthy volunteers. Partially water-suppressed (1)H MRS data sets were acquired at 3T from four different gray matter (GM)/white matter (WM) volumes. Brain temperatures were determined from the chemical-shift difference between the CH(3) of N-acetyl aspartate (NAA) at 2.01 ppm and water. Brain temperatures in (1)H MRS voxels of 2 x 2 x 2 cm(3) showed no substantial heterogeneity. The volume-averaged temperature from single-voxel spectroscopy was compared with body temperatures obtained from the oral cavity, tympanum, and temporal artery regions. The mean brain parenchyma temperature was 0.5 degrees C cooler than readings obtained from three extra-brain sites (P < 0.01). (1)H MRS imaging (MRSI) data were acquired from a slice encompassing the single-voxel volumes to assess the ability of spectroscopic imaging to determine regional brain temperature within the imaging slice. Brain temperature away from the center of the brain determined by MRSI differed from that obtained by single-voxel MRS in the same brain region, possibly due to a poor line width (LW) in MRSI. The data are discussed in the light of proposed brain-body temperature gradients and the use of (1)H MRSI to monitor brain temperature in pathologies, such as brain trauma.

  15. Temperature and moisture effects on greenhouse gas emissions from deep active-layer boreal soils

    SciTech Connect

    Bond-Lamberty, Benjamin; Smith, Ashly P.; Bailey, Vanessa L.

    2016-12-21

    Rapid climatic changes, rising air temperatures, and increased fires are expected to drive permafrost degradation and alter soil carbon (C) cycling in many high-latitude ecosystems. How these soils will respond to changes in their temperature, moisture, and overlying vegetation is highly uncertain, but critical to understand given the large soil C stocks in these regions. We used a laboratory experiment to examine how temperature and moisture control CO2 and CH4 emissions from mineral soils sampled from the bottom of the annual active layer, i.e. directly above permafrost, in an Alaskan boreal forest. Gas emissions from thirty cores, subjected to two temperatures and either field moisture conditions or experimental drought, were tracked over a 100-day incubation; we also measured a variety of physical and chemical characteristics of the cores. Gravimetric water content was 0.31 ± 0.12 (unitless) at the beginning of the incubation; cores at field moisture were unchanged at the end, but drought cores had declined to 0.06 ± 0.04. Carbon dioxide fluxes were strongly influenced by incubation chamber temperature, core water content, and percent soil nitrogen, and had a temperature sensitivity (i.e. Q10) of 1.3 and 1.9 for the field moisture and drought treatments, respectively. Methane emissions were most strongly correlated with percent nitrogen, but neither temperature nor water content was a significant first-order predictor of CH4 fluxes. The cumulative production of C from CO2 was over six orders of magnitudes higher than that from CH4. These results suggest that deep active-layer soils may be much more sensitive to changes in moisture than to temperature, a critical factor as discontinuous permafrost melts in interior Alaska. Deep but unfrozen high-latitude soils have been shown to be strongly affected by long-term experimental warming, and these results provide insight into their future dynamics and feedback potential with future climate change.

  16. Variation of the temperature gradient in the solar photosphere with magnetic activity

    NASA Astrophysics Data System (ADS)

    Faurobert, M.; Balasubramanian, R.; Ricort, G.

    2016-10-01

    Context. The contribution of quiet-Sun regions to the solar irradiance variability is currently unclear. Some solar-cycle variations of the quiet-Sun physical structure, such as the temperature gradient or the photospheric radius, might affect the irradiance. Aims: We intend to investigate possible variations of the photospheric temperature gradient with magnetic activity. Methods: We used high-resolution center-to-limb observations of the FeI 630.15 nm line profile in the quiet Sun performed onboard the Hinode satellite on 2007, December 19, and on 2013, December 7, that is, close to a minimum and a maximum of magnetic activity, respectively. We analyzed samples of 10″ × 10″ internetwork regions. The wings of the FeI 630.15 nm line were used in a non-standard way to recover images at roughly constant continuum optical depths above the continuum formation level. The image formation height is derived from measuring its perspective shift with respect to the continuum image, both observed away from disk center. The measurement relies on a cross-spectral method that is not limited by the spatial resolution of the SOT telescope and does not rely on any radiative transfer computation. The radiation temperature measured in the images is related to the photospheric temperature at their respective formation height. Results: The method allows us to investigate the temperature gradient in the low photosphere at altitudes of between 0 and 60 km above the 500 nm continuum formation height. In this layer the internetwork temperature gradient appears steeper in our 2013 sample than in the sample of 2007 in the northern hemisphere, whereas we detect no significant change in the southern hemisphere. We argue that this might be related to some strong hemispheric asymmetry of the magnetic activity at the solar maximum of cycle 24. Conclusions: Structural changes have been observed in numerical simulations of the magneto-convection at the surface of the Sun where the increase of

  17. Scaling of precipitation extremes with temperature in the French Mediterranean region: What explains the hook shape?

    NASA Astrophysics Data System (ADS)

    Drobinski, P.; Alonzo, B.; Bastin, S.; Silva, N. Da; Muller, C.

    2016-04-01

    Expected changes to future extreme precipitation remain a key uncertainty associated with anthropogenic climate change. Extreme precipitation has been proposed to scale with the precipitable water content in the atmosphere. Assuming constant relative humidity, this implies an increase of precipitation extremes at a rate of about 7% °C-1 globally as indicated by the Clausius-Clapeyron relationship. Increases faster and slower than Clausius-Clapeyron have also been reported. In this work, we examine the scaling between precipitation extremes and temperature in the present climate using simulations and measurements from surface weather stations collected in the frame of the HyMeX and MED-CORDEX programs in Southern France. Of particular interest are departures from the Clausius-Clapeyron thermodynamic expectation, their spatial and temporal distribution, and their origin. Looking at the scaling of precipitation extreme with temperature, two regimes emerge which form a hook shape: one at low temperatures (cooler than around 15°C) with rates of increase close to the Clausius-Clapeyron rate and one at high temperatures (warmer than about 15°C) with sub-Clausius-Clapeyron rates and most often negative rates. On average, the region of focus does not seem to exhibit super Clausius-Clapeyron behavior except at some stations, in contrast to earlier studies. Many factors can contribute to departure from Clausius-Clapeyron scaling: time and spatial averaging, choice of scaling temperature (surface versus condensation level), and precipitation efficiency and vertical velocity in updrafts that are not necessarily constant with temperature. But most importantly, the dynamical contribution of orography to precipitation in the fall over this area during the so-called "Cevenoles" events, explains the hook shape of the scaling of precipitation extremes.

  18. Estimation of sea surface temperature from remote sensing in the 11-13 micron window region

    NASA Technical Reports Server (NTRS)

    Prabhakara, C.; Dalu, G.; Kunde, V. G.

    1974-01-01

    The Nimbus 3 and 4 IRIS spectral data in the 11-13 micron water vapor window region are analyzed to determine the sea surface temperature (SST). The high spectral resolution data of IRIS are averaged over approximately 1 micron wide intervals to simulate channels of a radiometer to measure the SST. Three channels are utilized to measure SST over cloud-free oceans. However, two of these channels are sufficient in routine SST determination. The differential absorption properties of water vapor in the two channels enable one to determine the water vapor absorption correction without detailed knowledge of the vertical profiles of temperature and water vapor. The feasibility of determining the SST is demonstrated globally with Nimbus 3 data where cloud-free areas can be selected with the help of albedo data from the MRIR experiment on board the same satellite.

  19. Universal inverse power-law distribution for temperature and rainfall in the UK region

    NASA Astrophysics Data System (ADS)

    Selvam, A. M.

    2014-06-01

    Meteorological parameters, such as temperature, rainfall, pressure, etc., exhibit selfsimilar space-time fractal fluctuations generic to dynamical systems in nature such as fluid flows, spread of forest fires, earthquakes, etc. The power spectra of fractal fluctuations display inverse power-law form signifying long-range correlations. A general systems theory model predicts universal inverse power-law form incorporating the golden mean for the fractal fluctuations. The model predicted distribution was compared with observed distribution of fractal fluctuations of all size scales (small, large and extreme values) in the historic month-wise temperature (maximum and minimum) and total rainfall for the four stations Oxford, Armagh, Durham and Stornoway in the UK region, for data periods ranging from 92 years to 160 years. For each parameter, the two cumulative probability distributions, namely cmax and cmin starting from respectively maximum and minimum data value were used. The results of the study show that (i) temperature distributions (maximum and minimum) follow model predicted distribution except for Stornowy, minimum temperature cmin. (ii) Rainfall distribution for cmin follow model predicted distribution for all the four stations. (iii) Rainfall distribution for cmax follows model predicted distribution for the two stations Armagh and Stornoway. The present study suggests that fractal fluctuations result from the superimposition of eddy continuum fluctuations.

  20. Characteristics of wettedness and equi-skin temperature line in the evaporative regulation region

    NASA Astrophysics Data System (ADS)

    Mochida, T.

    1983-07-01

    As a result of the analysis of physiological experimental data, the characteristics of the wettedness were clarified, i.e., the value of the wettedness is not constant but differs in accordance with the environmental humidity even when the skin temperature is the same, and it was shown that the evaporative heat loss from the skin surface is inversely proportional to the wetttedness. Based on the properties of the wetedness observed, a new thermal sensation chart in the evaporative regulation region was proposed as an index for evaluating the warmth or the coldness in the environment. The feature of the present chart is that the locus of the equal skin temperature appears as a curved line on the psychrometric chart and that the wettedness on the equi-skin temperature line is not constant but takes varying values. The curved equal skin temperature line means that the influence of the environmental humidity on thermal sensation becomes smaller as the humidity of the environmental humidity on thermal sensation becomes smaller as the humidity of the environment is lowered.

  1. Comparison of Model and Observed Regional Temperature Changes During the Past 40 Years

    NASA Technical Reports Server (NTRS)

    Russell, Gary L.; Miller, James R.; Rind, David; Ruedy, Reto A.; Schmidt, Gavin A.; Sheth, Sukeshi

    1999-01-01

    Results are presented for six simulations of the Goddard Institute for Space Studies (GISS) global atmosphere-ocean model for the years 1950 to 2099. There are two control simulations with constant 1950 atmospheric composition from different initial states, two GHG experiments with observed greenhouse gases up to 1990 and compounded .5% CO2 annual increases thereafter, and two GHG+SO4 experiments with the same varying greenhouse gases plus varying tropospheric sulfate aerosols. Surface air temperature trends in the two GHG experiments are compared between themselves and with the observed temperature record from 1960 and 1998. All comparisons show high positive spatial correlation in the northern hemisphere except in summer when the greenhouse signal is weakest. The GHG+SO4 experiments show weaker correlations. In the southern hemisphere, correlations are either weak or negative which in part are due to the model's unrealistic interannual variability of southern sea ice cover. The model results imply that temperature changes due to forcing by increased greenhouse gases have risen above the level of regional interannual temperature variability in the northern hemisphere over the past 40 years. This period is thus an important test of reliability of coupled climate models.

  2. Climatic variability of river outflow in the Pantanal region and the influence of sea surface temperature

    NASA Astrophysics Data System (ADS)

    Silva, Carlos Batista; Silva, Maria Elisa Siqueira; Ambrizzi, Tércio

    2016-03-01

    This paper investigates possible linear relationships between climate, hydrology, and oceanic surface variability in the Pantanal region (in South America's central area), over interannual and interdecadal time ranges. In order to verify the mentioned relations, lagged correlation analysis and linear adjustment between river discharge at the Pantanal region and sea surface temperature were used. Composite analysis for atmospheric fields, air humidity flux divergence, and atmospheric circulation at low and high levels, for the period between 1970 and 2003, was analyzed. Results suggest that the river discharge in the Pantanal region is linearly associated with interdecadal and interannual oscillations in the Pacific and Atlantic oceans, making them good predictors to continental hydrological variables. Considering oceanic areas, 51 % of the annual discharge in the Pantanal region can be linearly explained by mean sea surface temperature (SST) in the Subtropical North Pacific, Tropical North Pacific, Extratropical South Pacific, and Extratropical North Atlantic over the period. Considering a forecast approach in seasonal scale, 66 % of the monthly discharge variance in Pantanal, 3 months ahead of SST, is explained by the oceanic variables, providing accuracy around 65 %. Annual discharge values in the Pantanal region are strongly related to the Pacific Decadal Oscillation (PDO) variability (with 52 % of linear correlation), making it possible to consider an interdecadal variability and a consequent subdivision of the whole period in three parts: 1st (1970-1977), 2nd (1978-1996), and 3rd (1997-2003) subperiods. The three subperiods coincide with distinct PDO phases: negative, positive, and negative, respectively. Convergence of humidity flux at low levels and the circulation pattern at high levels help to explain the drier and wetter subperiods. During the wetter 2nd subperiod, the air humidity convergence at low levels is much more evident than during the other two

  3. Regional variation in the temperature sensitivity of soil organic matter decomposition in China's forests and grasslands.

    PubMed

    Liu, Yuan; He, Nianpeng; Zhu, Jianxing; Xu, Li; Yu, Guirui; Niu, Shuli; Sun, Xiaomin; Wen, Xuefa

    2017-01-05

    How to assess the temperature sensitivity (Q10 ) of soil organic matter (SOM) decomposition and its regional variation with high accuracy is one of the largest uncertainties in determining the intensity and direction of the global carbon (C) cycle in response to climate change. In this study, we collected a series of soils from 22 forest sites and 30 grassland sites across China to explore regional variation in Q10 and its underlying mechanisms. We conducted a novel incubation experiment with periodically changing temperature (5-30 °C), while continuously measuring soil microbial respiration rates. The results showed that Q10 varied significantly across different ecosystems, ranging from 1.16 to 3.19 (mean 1.63). Q10 was ordered as follows: alpine grasslands (2.01) > temperate grasslands (1.81) > tropical forests (1.59) > temperate forests (1.55) > subtropical forests (1.52). The Q10 of grasslands (1.90) was significantly higher than that of forests (1.54). Furthermore, Q10 significantly increased with increasing altitude and decreased with increasing longitude. Environmental variables and substrate properties together explained 52% of total variation in Q10 across all sites. Overall, pH and soil electrical conductivity primarily explained spatial variation in Q10 . The general negative relationships between Q10 and substrate quality among all ecosystem types supported the C quality temperature (CQT) hypothesis at a large scale, which indicated that soils with low quality should have higher temperature sensitivity. Furthermore, alpine grasslands, which had the highest Q10 , were predicted to be more sensitive to climate change under the scenario of global warming.

  4. Models of H II regions - Heavy element opacity, variation of temperature

    NASA Technical Reports Server (NTRS)

    Rubin, R. H.

    1985-01-01

    A detailed set of H II region models that use the same physics and self-consistent input have been computed and are used to examine where in parameter space the effects of heavy element opacity is important. The models are briefly described, and tabular data for the input parameters and resulting properties of the models are presented. It is found that the opacities of C, Ne, O, and to a lesser extent N play a vital role over a large region of parameter space, while S and Ar opacities are negligible. The variation of the average electron temperature T(e) of the models with metal abundance, density, and T(eff) is investigated. It is concluded that by far the most important determinator of T(e) is metal abundance; an almost 7000 K difference is expected over the factor of 10 change from up to down abundances.

  5. The plasma-wall interaction region: a key low temperature plasma for controlled fusion

    NASA Astrophysics Data System (ADS)

    Counsell, G. F.

    2002-08-01

    The plasma-wall interaction region of a fusion device provides the interface between the hot core plasma and the material surfaces. To obtain acceptably low levels of erosion from these surfaces requires most of the power leaving the core to be radiated. This is accomplished in existing devices by encouraging plasma detachment, in which the hot plasma arriving in the region is cooled by volume recombination and ion-neutral momentum transfer with a dense population of neutrals recycled from the surface. The result is a low temperature (1 eV1019 m-3) but weakly ionized (n0>1020 m-3, ne/n0<0.1) plasma found nowhere else in the fusion environment. This plasma provides many of the conditions found in industrial plasmas exploiting plasma chemistry and the presence of carbon in the region (in the form of carbon-fibre composite used in the plasma facing materials) can result in the formation of deposited hydrocarbon films. The plasma-wall interaction region is therefore among the most difficult in fusion to model, requiring an understanding of atomic, molecular and surface physics issues.

  6. Forced and unforced ocean temperature changes in Atlantic and Pacific tropical cyclogenesis regions.

    PubMed

    Santer, B D; Wigley, T M L; Gleckler, P J; Bonfils, C; Wehner, M F; Achutarao, K; Barnett, T P; Boyle, J S; Brüggemann, W; Fiorino, M; Gillett, N; Hansen, J E; Jones, P D; Klein, S A; Meehl, G A; Raper, S C B; Reynolds, R W; Taylor, K E; Washington, W M

    2006-09-19

    Previous research has identified links between changes in sea surface temperature (SST) and hurricane intensity. We use climate models to study the possible causes of SST changes in Atlantic and Pacific tropical cyclogenesis regions. The observed SST increases in these regions range from 0.32 degrees C to 0.67 degrees C over the 20th century. The 22 climate models examined here suggest that century-timescale SST changes of this magnitude cannot be explained solely by unforced variability of the climate system. We employ model simulations of natural internal variability to make probabilistic estimates of the contribution of external forcing to observed SST changes. For the period 1906-2005, we find an 84% chance that external forcing explains at least 67% of observed SST increases in the two tropical cyclogenesis regions. Model "20th-century" simulations, with external forcing by combined anthropogenic and natural factors, are generally capable of replicating observed SST increases. In experiments in which forcing factors are varied individually rather than jointly, human-caused changes in greenhouse gases are the main driver of the 20th-century SST increases in both tropical cyclogenesis regions.

  7. Comparing regional precipitation and temperature extremes in climate model and reanalysis products.

    PubMed

    Angélil, Oliver; Perkins-Kirkpatrick, Sarah; Alexander, Lisa V; Stone, Dáithí; Donat, Markus G; Wehner, Michael; Shiogama, Hideo; Ciavarella, Andrew; Christidis, Nikolaos

    2016-09-01

    A growing field of research aims to characterise the contribution of anthropogenic emissions to the likelihood of extreme weather and climate events. These analyses can be sensitive to the shapes of the tails of simulated distributions. If tails are found to be unrealistically short or long, the anthropogenic signal emerges more or less clearly, respectively, from the noise of possible weather. Here we compare the chance of daily land-surface precipitation and near-surface temperature extremes generated by three Atmospheric Global Climate Models typically used for event attribution, with distributions from six reanalysis products. The likelihoods of extremes are compared for area-averages over grid cell and regional sized spatial domains. Results suggest a bias favouring overly strong attribution estimates for hot and cold events over many regions of Africa and Australia, and a bias favouring overly weak attribution estimates over regions of North America and Asia. For rainfall, results are more sensitive to geographic location. Although the three models show similar results over many regions, they do disagree over others. Equally, results highlight the discrepancy amongst reanalyses products. This emphasises the importance of using multiple reanalysis and/or observation products, as well as multiple models in event attribution studies.

  8. Regional variation in myofilament length-dependent activation.

    PubMed

    Cazorla, Olivier; Lacampagne, Alain

    2011-07-01

    The Frank-Starling law is an important regulatory mechanism of the heart that links the end-diastolic volume with the systolic ejection fraction. This beat-to-beat regulation of the heart, underlined at the cellular level by higher myofilament calcium sensitivity at longer sarcomere length, is known as length-dependent activation or stretch sensitization of activation. However, the heart is structurally and functionally heterogeneous and asymmetrical. Specifically, contractile properties are not uniform within the left ventricle partly due to transmural differences in action potential waveforms and calcium homeostasis. The present review will focus on the role of the contractile machinery in the transmural contractile heterogeneity and its adaptation to changes in muscle strain. The expression of different myosin isoforms, the level of titin-based passive tension, and thin and thick sarcomeric regulatory proteins are considered to explain the regional cellular contractile properties. Finally, the importance of transmural heterogeneity of length-dependent activation and the consequences of its modification on the heart mechanics are discussed. Despite extensive research since the characterization of the Frank-Starling law, the molecular mechanisms by which strain information is transduced to the contractile machinery have not been fully determined yet.

  9. Repetitive Transcranial Magnetic Stimulation Activates Specific Regions in Rat Brain

    NASA Astrophysics Data System (ADS)

    Ji, Ru-Rong; Schlaepfer, Thomas E.; Aizenman, Carlos D.; Epstein, Charles M.; Qiu, Dike; Huang, Justin C.; Rupp, Fabio

    1998-12-01

    Repetitive transcranial magnetic stimulation (rTMS) is a noninvasive technique to induce electric currents in the brain. Although rTMS is being evaluated as a possible alternative to electroconvulsive therapy for the treatment of refractory depression, little is known about the pattern of activation induced in the brain by rTMS. We have compared immediate early gene expression in rat brain after rTMS and electroconvulsive stimulation, a well-established animal model for electroconvulsive therapy. Our result shows that rTMS applied in conditions effective in animal models of depression induces different patterns of immediate-early gene expression than does electroconvulsive stimulation. In particular, rTMS evokes strong neural responses in the paraventricular nucleus of the thalamus (PVT) and in other regions involved in the regulation of circadian rhythms. The response in PVT is independent of the orientation of the stimulation probe relative to the head. Part of this response is likely because of direct activation, as repetitive magnetic stimulation also activates PVT neurons in brain slices.

  10. In-depth survey of sunspot and active region catalogs

    NASA Astrophysics Data System (ADS)

    Lefèvre, Laure; Clette, Frédéric; Baranyi, Tunde

    2011-08-01

    When consulting detailed photospheric catalogs for solar activity studies spanning long time intervals, solar physicists face multiple limitations in the existing catalogs: finite or fragmented time coverage, limited time overlap between catalogs and even more importantly, a mismatch in contents and conventions. In view of a study of new sunspot-based activity indices, we have conducted a comprehensive survey of existing catalogs. In a first approach, we illustrate how the information from parallel catalogs can be merged to form a much more comprehensive record of sunspot groups. For this, we use the unique Debrecen Photoheliographic Data (DPD), which is already a composite of several ground observatories and SOHO data, and the USAF/Mount Wilson catalog from the Solar Optical Observing Network (SOON). We also describe our semi-interactive cross-identification method, which was needed to match the non-overlapping solar active region nomenclature, the most critical and subtle step when working with multiple catalogs. This effort, focused here first on the last two solar cycles, should lead to a better central database collecting all available sunspot group parameters to address future solar cycle studies beyond the traditional sunspot index time series Ri.

  11. Surface activation-based nanobonding and interconnection at room temperature

    NASA Astrophysics Data System (ADS)

    Howlader, M. M. R.; Yamauchi, A.; Suga, T.

    2011-02-01

    Flip chip nanobonding and interconnect system (NBIS) equipment with high precision alignment has been developed based on the surface activated bonding method for high-density interconnection and MEMS packaging. The 3σ alignment accuracy in the IR transmission system was approximately ±0.2 µm. The performance of the NBIS has been preliminarily investigated through bonding between relatively rough surfaces of copper through silicon vias (Cu-TSVs) and gold-stud bumps (Au-SBs), and smooth surfaces of silicon wafers. The Cu-TSVs of 55 µm diameter and the Au-SBs of 35 µm diameter with ~6-10 nm surface roughness (RMS) were bonded at room temperature after surface activation using an argon fast atom beam (Ar-FAB) under 0.16 N per bump. Silicon wafers of 50 mm diameter with ~0.2 nm RMS surface roughness were bonded without heating after surface activation. Void-free interfaces both in Cu-TSV/Au-SB and silicon/silicon with bonding strength equivalent to bulk fracture of Au and silicon, respectively, were achieved. A few nm thick amorphous layers were observed across the silicon/silicon interface that was fabricated by the Ar-FAB. This study in the interconnection and bonding facilitates the required three-dimensional integration on the same surface for high-density electronic and biomedical systems.

  12. Contrasting Role of Temperature in Structuring Regional Patterns of Invasive and Native Pestilential Stink Bugs

    PubMed Central

    Venugopal, P. Dilip; Dively, Galen P.; Herbert, Ames; Malone, Sean; Whalen, Joanne; Lamp, William O.

    2016-01-01

    Objectives Assessment and identification of spatial structures in the distribution and abundance of invasive species is important for unraveling the underlying ecological processes. The invasive agricultural insect pest Halyomorpha halys that causes severe economic losses in the United States is currently expanding both within United States and across Europe. We examined the drivers of H. halys invasion by characterizing the distribution and abundance patterns of H. halys and native stink bugs (Chinavia hilaris and Euschistus servus) across eight different spatial scales. We then quantified the interactive and individual influences of temperature, and measures of resource availability and distance from source populations, and their relevant spatial scales. We used Moran’s Eigenvector Maps based on Gabriel graph framework to quantify spatial relationships among the soybean fields in mid-Atlantic Unites States surveyed for stink bugs. Findings Results from the multi-spatial scale, multivariate analyses showed that temperature and its interaction with resource availability and distance from source populations structures the patterns in H. halys at very broad spatial scale. H. halys abundance decreased with increasing average June temperature and distance from source population. H. halys were not recorded at fields with average June temperature higher than 23.5°C. In parts with suitable climate, high H. halys abundance was positively associated with percentage developed open area and percentage deciduous forests at 250m scale. Broad scale patterns in native stink bugs were positively associated with increasing forest cover and, in contrast to the invasive H. halys, increasing mean July temperature. Our results identify the contrasting role of temperature in structuring regional patterns in H. halys and native stink bugs, while demonstrating its interaction with resource availability and distance from source populations for structuring H. halys patterns. Conclusion

  13. Multicenter study on the asymmetry of skin temperature in complex regional pain syndrome

    PubMed Central

    Cho, Chan Woo; Nahm, Francis Sahngun; Choi, Eunjoo; Lee, Pyung-Bok; Jang, In-Ki; Lee, Chul Joong; Kim, Yong Chul; Lee, Sang Chul

    2016-01-01

    Abstract According to the International Association for the Study of Pain (IASP) and American Medical Association (AMA), the diagnostic criteria for complex regional pain syndrome (CRPS) require the presence of skin temperature asymmetry. In CRPS, it is generally accepted that the temperature of skin of affected limbs changes from warm to cold; however, in our clinical practice, we have experienced many cases with different thermographic characteristics. Therefore, we conducted a retrospective multicenter study that examined the distribution of skin temperature in patients with CRPS and skin temperature asymmetry versus symptom duration. Patients diagnosed with type 1 or 2 CRPS were recruited. After confirming CRPS according to the IASP diagnostic criteria, infrared thermographic images were evaluated for skin temperature differences (ΔT) between the affected and unaffected limbs. A total of 296 patients with CRPS were included in this study. The median duration of symptoms was 6 months and the mean ± standard deviation of ΔT was –0.72 ± 1.65°C. A skin temperature difference between bilateral limbs (|ΔT|) of 1°C or less was seen in 131 patients (44.3%); thus, these 131 patients did not meet the IASP criteria for CRPS. Further, cool skin temperature was not observed in 88 patients (29.7%), meaning that these patients did not meet the AMA criteria for CRPS. There was no correlation between the symptom duration and ΔT (Spearman's rho = –0.075, P = 0.196) and there was no significant difference in the average ΔT among the 4 symptom duration groups (0–3 months, 4–6 months, 7–12 months, >12 months, P = 0.08). In conclusion, a considerable proportion of the patients that participated in this study did not meet the thermal criteria set forth by the IASP and AMA. Further, there was no correlation between symptom duration and skin temperature difference. PMID:28033251

  14. Numerical Simulation of a Solar Active Region. I: Bastille Day Flare

    NASA Astrophysics Data System (ADS)

    Vincent, Alain; Charbonneau, Paul; Dubé, Caroline

    2012-06-01

    We present three-dimensional unsteady modeling and numerical simulations of a coronal active region, carried out within the compressible single-fluid MHD approximation. We focus on AR 9077 on 14 July 2000, and the triggering of the X5.7 GOES X-ray class "Bastille Day" flare. We simulate only the lower corona, although we include a virtual photosphere and chromosphere below. The boundary conditions at the base of this layer are set using temperature maps from line intensities and line-of-sight magnetograms (SOHO/MDI). From the latter, we generate vector magnetograms using the force-free approximation; these vector magnetograms are then used to produce the boundary condition on the velocity field using a minimum energy principle (Longcope, Astrophys. J. 612, 1181, 2004). The reconnection process is modeled through a dynamical hyper-resistivity which is activated when the current exceeds a critical value (Klimas et al., J. Geophys. Res. 109, 2218, 2004). Comparing the time series of X-ray fluxes recorded by GOES with modeled time series of various mean physical variables such as current density, Poynting energy flux, or radiative loss inside the active region, we can demonstrate that the model properly captures the evolution of an active region over a day and, in particular, is able to explain the initiation of the flare at the observed time.

  15. Rethinking the longitudinal stream temperature paradigm: region-wide comparison of thermal infrared imagery reveals unexpected complexity of river temperatures

    EPA Science Inventory

    We used an extensive dataset of remotely sensed summertime river temperature to compare longitudinal profiles (temperature versus distance) for 54 rivers in the Pacific Northwest. We evaluated (1) how often profiles fit theoretical expectations of asymptotic downstream warming, a...

  16. On the modified active region design of interband cascade lasers

    SciTech Connect

    Motyka, M.; Ryczko, K.; Dyksik, M.; Sęk, G.; Misiewicz, J.; Weih, R.; Dallner, M.; Kamp, M.; Höfling, S.

    2015-02-28

    Type II InAs/GaInSb quantum wells (QWs) grown on GaSb or InAs substrates and designed to be integrated in the active region of interband cascade lasers (ICLs) emitting in the mid infrared have been investigated. Optical spectroscopy, combined with band structure calculations, has been used to probe their electronic properties. A design with multiple InAs QWs has been compared with the more common double W-shaped QW and it has been demonstrated that it allows red shifting the emission wavelength and enhancing the transition oscillator strength. This can be beneficial for the improvements of the ICLs performances, especially when considering their long-wavelength operation.

  17. Chromospheric magnetic fields of an active region filament

    NASA Astrophysics Data System (ADS)

    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.

  18. SIGN SINGULARITY AND FLARES IN SOLAR ACTIVE REGION NOAA 11158

    SciTech Connect

    Sorriso-Valvo, L.; De Vita, G.; Kazachenko, M. D.; Krucker, S.; Welsch, B. T.; Fisher, G. H.; Primavera, L.; Servidio, S.; Lepreti, F.; Carbone, V.; Vecchio, A.

    2015-03-01

    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 Extreme-Ultra-Violet and X-ray flux suggest that eruption of large flares can be linked to the small-scale properties of the current structures.

  19. Physicochemical effect of activation temperature on the sorption properties of pine shell activated carbon.

    PubMed

    Wasim, Agha Arslan; Khan, Muhammad Nasiruddin

    2017-03-01

    Activated carbons produced from a variety of raw materials are normally selective towards a narrow range of pollutants present in wastewater. This study focuses on shifting the selectivity of activated carbon from inorganic to organic pollutants using activation temperature as a variable. The material produced from carbonization of pine shells substrate was activated at 250°C and 850°C. Both adsorbents were compared with commercial activated carbon for the sorption of lead, cadmium, methylene blue, methyl blue, xylenol orange, and crystal violet. It was observed that carbon activated at 250°C was selective for lead and cadmium whereas the one activated at 850°C was selective for the organic dyes. The Fourier transform infrared spectroscopy study revealed that AC850 had less surface functional groups as compared to AC250. Point of zero charge and point of zero salt effect showed that AC250 had acidic groups at its surface. Scanning electron microscopy depicted that increase in activation temperature resulted in an increase in pore size of activated carbon. Both AC250 and AC850 followed pseudo-second-order kinetics. Temkin isotherm model was a best fit for empirical data obtained at equilibrium. The model also showed that sorption process for both AC250 and AC850 was physisorption.

  20. Focused ultrasound modulates region-specific brain activity

    PubMed Central

    Yoo, Seung-Schik; Bystritsky, Alexander; Lee, Jong-Hwan; Zhang, Yongzhi; Fischer, Krisztina; Min, Byoung-Kyong; McDannold, Nathan J.; Pascual-Leone, Alvaro; Jolesz, Ferenc A.

    2012-01-01

    We demonstrated the in vivo feasibility of using focused ultrasound (FUS) to transiently modulate (through either stimulation or suppression) the function of regional brain tissue in rabbits. FUS was delivered in a train of pulses at low acoustic energy, far below the cavitation threshold, to the animal's somatomotor and visual areas, as guided by anatomical and functional information from magnetic resonance imaging (MRI). The temporary alterations in the brain function affected by the sonication were characterized by both electrophysiological recordings and functional brain mapping achieved through the use of functional MRI (fMRI). The modulatory effects were bimodal, whereby the brain activity could either be stimulated or selectively suppressed. Histological analysis of the excised brain tissue after the sonication demonstrated that the FUS did not elicit any tissue damages. Unlike transcranial magnetic stimulation, FUS can be applied to deep structures in the brain with greater spatial precision. Transient modulation of brain function using image-guided and anatomically-targeted FUS would enable the investigation of functional connectivity between brain regions and will eventually lead to a better understanding of localized brain functions. It is anticipated that the use of this technology will have an impact on brain research and may offer novel therapeutic interventions in various neurological conditions and psychiatric disorders. PMID:21354315

  1. Slow Magnetosonic Waves and Fast Flows in Active Region Loops

    NASA Technical Reports Server (NTRS)

    Ofman, L.; Wang, T. J.; Davila, J. M.

    2012-01-01

    Recent extreme ultraviolet 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 (approx 100-300 km/s) quasiperiodic 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 magnetosonic waves is close to the coronal sound speed. When the amplitude of the driving pulses is increased we find that slow shock-like wave trains are produced. When the upflows are driven periodically, undamped oscillations are produced with periods determined by the periodicity of the upflows. Based on the results of the 3D MHD model we suggest that the observed slow magnetosonic waves and persistent upflows may be produced by the same impulsive events at the bases of ARs.

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

    PubMed Central

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

    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-wide expression during mid-exponential growth on rich (LB) and minimal (M9) medium. The identified TARs account for 77.3% of the genes as they are currently annotated and additionally we find 84 putative non-coding RNAs (ncRNAs) and 127 antisense transcripts. One ncRNA, ncr22, is predicted to act as a translational control on cstA and an antisense transcript was observed opposite the housekeeping sigma factor sigA. Through this work we have discovered a long conserved 3′ untranslated region (UTR) in a group of membrane-associated genes that is predicted to fold into a large and highly stable secondary structure. One of the genes having this tail is efeN, which encodes a target of the twin-arginine translocase (Tat) protein translocation system. PMID:19682248

  3. Generator of chemically active low-temperature plasma

    NASA Astrophysics Data System (ADS)

    Tyuftyaev, A. S.; Gadzhiev, M. Kh; Sargsyan, M. A.; Demirov, N. A.; Spector, N. O.

    2016-11-01

    A new generator of high enthalpy (H 0 > 40 kJ/g), chemically active nitrogen and air plasmas was designed and constructed. Main feature of the generator is an expanding channel of an output electrode; the generator belongs to the class of DC plasma torches with thermionic cathode with an efficiency of 80%. The generator ensures the formation of a slightly divergent plasma jet (2α = 12°) with a diameter of D = 10-12 mm, an electric arc maximum power of 20-50 kW, plasma forming gas flow rate 1.0-2.0 g/s, and the average plasma temperature at an outlet of 8000-11000 K.

  4. Effects of magnetic field intensity on carbon diffusion coefficient in pure iron in γ-Fe temperature region

    NASA Astrophysics Data System (ADS)

    Wu, Yan; Duan, Guosheng; Zhao, Xiang

    2015-03-01

    Effects of magnetic field intensity on carbon diffusion coefficient in pure iron in the γ-Fe temperature region were investigated using carburizing technology. The carbon penetration profiles from the iron surface to interior were measured by field emission electron probe microanalyzer. The carbon diffusion coefficient in pure iron carburized with different magnetic field intensities was calculated according to the Fick's second law. It was found that the magnetic field intensity could obviously affect the carbon diffusion coefficient in pure iron in the γ-Fe temperature region, and the carbon diffusion coefficient decreased obviously with the enhancement of magnetic field intensity, when the magnetic field intensity was higher than 1 T, the carbon diffusion coefficient in field annealed specimen was less than half of that of the nonfield annealed specimen, further enhancing the magnetic field intensity, the carbon diffusion coefficient basically remains unchanged. The stiffening of lattice due to field-induced magnetic ordering was responsible for an increase in activation barrier for jumping carbon atoms. The greater the magnetic field intensity, the stronger the inhibiting effect of magnetic field on carbon diffusion.

  5. Comparison of Solar Active Region Complexity Andgeomagnetic Activity from 1996 TO 2014

    NASA Astrophysics Data System (ADS)

    Tanskanen, E. I.; Nikbakhsh, S.; Perez-Suarez, D.; Hackman, T.

    2015-12-01

    We have studied the influence of magnetic complexity of solar Active Regions (ARs)on geomagnetic activity from 1996 to 2014. Sunspots are visual indicators of ARswhere the solar magnetic field is disturbed. We have used International, American,Space Environment Service Center (SESC) and Space Weather Prediction Center(SWPC) sunspot numbers to examine ARs. Major manifestations of solar magneticactivity, such as flares and Coronal Mass Ejections (CMEs), are associated withARs. For this study we chose the Mount Wilson scheme. It classifies ARs in terms oftheir magnetic topology from the least complex (?) to the most complex one ( ?).Several cases have been found where the more complex structures produce strongerflares and CMEs than the less complex ones. We have a list of identified substormsavailable with different phases and their durations. This will be compared to ourmagnetic complexity data to analyse the effects of active region magnetic complexityto the magnetic activity on the vicinity of the Earth.

  6. Using the Surface Temperature-Albedo Space to Separate Regional Soil and Vegetation Temperatures from ASTER Data

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil and vegetation component temperatures in non-isothermal pixels encapsulate more physical meaning and are more applicable than composite temperatures. The component temperatures however are difficult to be obtained from thermal infrared (TIR) remote sensing data provided by single view angle obs...

  7. Micromachined Active Magnetic Regenerator for Low-Temperature Magnetic Coolers

    NASA Technical Reports Server (NTRS)

    Chen, Weibo; Jaeger, Michael D.

    2013-01-01

    A design of an Active Magnetic Regenerative Refrigeration (AMRR) system has been developed for space applications. It uses an innovative 3He cryogenic circulator to provide continuous remote/distributed cooling at temperatures in the range of 2 K with a heat sink at about 15 K. A critical component technology for this cooling system is a highly efficient active magnetic regenerator, which is a regenerative heat exchanger with its matrix material made of magnetic refrigerant gadolinium gallium garnet (GGG). Creare Inc. is developing a microchannel GGG regenerator with an anisotropic structured bed for high system thermal efficiency. The regenerator core consists of a stack of thin, single-crystal GGG disks alternating with thin polymer insulating layers. The insulating layers help minimize the axial conduction heat leak, since GGG has a very high thermal conductivity in the regenerator s operating temperature range. The GGG disks contain micro channels with width near 100 micrometers, which enhance the heat transfer between the circulating flow and the refrigerant bed. The unique flow configuration of the GGG plates ensures a uniform flow distribution across the plates. The main fabrication challenges for the regenerator are the machining of high-aspect-ratio microchannels in fragile, single-crystal GGG disks and fabrication and assembly of the GGG insulation layers. Feasibility demonstrations to date include use of an ultrashort- pulse laser to machine microchannels without producing unacceptable microcracking or deposition of recast material, as shown in the figure, and attachment of a thin insulation layer to a GGG disk without obstructing the flow paths. At the time of this reporting, efforts were focused on improving the laser machining process to increase machining speed and further reduce microcracking.

  8. Temperature and Microbial Activity Effects on Soil Carbon Stabilization

    NASA Astrophysics Data System (ADS)

    Fissore, C.; van Diepen, L.; Wixon, D.; Marin-Spiotta, E.; Giardina, C. P.

    2014-12-01

    Uncertainties on the importance of environmental controls on soil C stabilization and turnover limit accurate predictions of the rate and magnitude of the response of soils to climate change. Here we report results from a study of interactions among vegetation and soil microbial communities in North American forests across a highly constrained, 22OC gradient mean annual temperature (MAT) as a proxy for understanding changes with climate. Previous work indicated that turnover and amount of labile SOC responded negatively to MAT, whereas stable SOC was insensitive to temperature variation. Hardwood forests stored a larger amount of stable SOC, but with shorter mean residence times than paired pine forests. Our findings suggest that the interaction between vegetation composition and microbial communities may affect SOC accumulation and stabilization responses to rising temperature. To investigate these relationships, we characterized the microbial communities with Phospholipid Fatty Acid (PLFA) analysis. PLFA analyses indicate complex microbial responses to increased MAT and vegetation composition. Microbial biomass declined with MAT in conifer forests and increased in hardwood forests. Relative abundance of actinomycetes increased with MAT for both forest types, and was correlated with amount and turnover of active SOC. The relative abundance of fungi decreased with increasing MAT, while gram+ bacteria increased, such that fungi:bacteria ratio decreased with MAT, with this trend being more pronounced for hardwood cover type. These results are consistent with a long-term warming experiment in a hardwood forest at the Harvard Forest LTER site, where after 12 years of warming the relative abundance of gram positive bacteria and actinomycetes increased, while fungal biomass decreased. In contrast, relationships between microbial groups and the stable fraction of SOC along the gradient were only observed in conifers. Increases in mean residence time of stable SOC were

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

    NASA Astrophysics Data System (ADS)

    Kumar, P.; Sokolik, I. N.; Nenes, A.

    2011-08-01

    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 describe the CCN activity of aged or hygroscopic dusts.

  10. Long-Period ULF Wave Activity in the Cusp Region

    NASA Astrophysics Data System (ADS)

    Pilipenko, V.; Belakhovsky, V.; Engebretson, M. J.; Kozlovsky, A.

    2013-12-01

    We compare simultaneous observations of long-period ULF wave activity from the Svalbard/IMAGE and Greenland fluxgate magnetometer profiles covering the expected cusp geomagnetic latitudes. Irregular Pulsations at Cusp Latitudes (IPCL) and narrow-band Pc5 waves are found to be a ubiquitous element of ULF activity in the dayside high-latitude region. To identify the ionospheric projections of the cusp, we use the width of the return signal of the SuperDARN radar covering the Svalbard archipelago, predictions of empirical cusp models, and augmented whenever possible by DMSP identification of magnetospheric boundary domains. The meridional spatial structure of IPCL/Pc5 pulsation spectral power has been found to have a localized latitudinal peak, but not under the cusp proper as was previously thought, but several degrees southward from the equatorward cusp boundary. Possible mechanisms and their relevance to observational data are discussed. The occurrence of IPCL and Pc5 waves in the dayside boundary layers is a challenge to modelers, because so far their mechanism has not been firmly identified.

  11. E region electric field dependence of the solar activity

    NASA Astrophysics Data System (ADS)

    Denardini, C. M.; Moro, J.; Resende, L. C. A.; Chen, S. S.; Schuch, N. J.; Costa, J. E. R.

    2015-10-01

    We have being studying the zonal and vertical E region electric field components inferred from the Doppler shifts of type 2 echoes (gradient drift irregularities) detected with the 50 MHz backscatter coherent radar set at São Luis, Brazil (SLZ, 2.3°S, 44.2°W) during the solar cycle 24. In this report we present the dependence of the vertical and zonal components of this electric field with the solar activity, based on the solar flux F10.7. For this study we consider the geomagnetically quiet days only (Kp ≤ 3+). A magnetic field-aligned-integrated conductivity model was developed for proving the conductivities, using the IRI-2007, the MISIS-2000, and the IGRF-11 models as input parameters for ionosphere, neutral atmosphere, and Earth magnetic field, respectively. The ion-neutron collision frequencies of all the species are combined through the momentum transfer collision frequency equation. The mean zonal component of the electric field, which normally ranged from 0.19 to 0.35 mV/m between the 8 and 18 h (LT) in the Brazilian sector, show a small dependency with the solar activity. Whereas the mean vertical component of the electric field, which normally ranges from 4.65 to 10.12 mV/m, highlights the more pronounced dependency of the solar flux.

  12. High temperature active heat exchanger research for latent heat storage

    NASA Astrophysics Data System (ADS)

    Alario, J.; Haslett, R.

    1982-02-01

    An active heat exchange method in a latent heat (salt) thermal energy storage system that prevents a low conductivity solid salt layer from forming on heat transfer surfaces was developed. An evaluation of suitable media with melting points in the temperature range of interest (250 to 400 C) limited the candidates to molten salts from the chloride, hydroxide and nitrate families, based on high storage capacity, good corrosion characteristics and availability in large quantities at reasonable cost. The specific salt recommended for laboratory tests was a choride eutectic (20.5KCL o 24.5NaCL o 55.MgCl2% by wt.), with a nominal melting point of 385 C. Various active heat exchange concepts were given a technical and economic comparison to a passive tube shell design for a reference application (300 MW sub t for 6 hours). Test hardware was then built for the most promising concept: a direct contact heat exchanger in which molten salt droplets are injected into a cooler counter flowing stream of liquid metal carrier fluid (lead/Bismuth).

  13. Estimating the regional climate responses over river basins to changes in tropical sea surface temperature patterns

    NASA Astrophysics Data System (ADS)

    Tsai, Chii-Yun; Forest, Chris E.; Wagener, Thorsten

    2015-10-01

    We investigate how to identify and assess teleconnection signals between anomalous patterns of sea surface temperature (SST) changes and climate variables related to hydrologic impacts over different river basins. The regional climate sensitivity to tropical SST anomaly patterns is examined through a linear relationship given by the global teleconnection operator (GTO, also generally called a sensitivity matrix or an empirical Green's function). We assume that the GTO defines a multilinear relation between SST forcing and regional climate response of a target area. The sensitivities are computed based on data from a large ensemble of simulations using the NCAR Community Atmospheric Model version 3.1 (CAM 3.1). The linear approximation is evaluated by comparing the linearly reconstructed response with both the results from the full non-linear atmospheric model and observational data. The results show that the linear approximation can capture regional climate variability that the CAM 3.1 AMIP-style simulations produce at seasonal scales for multiple river basins. The linear method can be used potentially for estimating drought conditions, river flow forecasting, and agricultural water management problems.

  14. The Effect of Lake Temperatures and Emissions on Ozone Exposure in the Western Great Lakes Region

    SciTech Connect

    Fast, Jerome D. ); Heilman, Warren E.

    2003-09-01

    A meteorological-chemical model with a 12-km horizontal grid spacing was used to simulate the evolution of ozone over the western Great Lakes region during a 30-day period in the summer of 1999. High ozone production rates were produced over the surface of the lakes as a result of stable atmospheric conditions that trapped ozone precursors within a shallow layer during the day. Simulations with lake temperatures derived from either satellite measurements or climatological values produced ozone mixing ratios over the lakes and around the lake shores that differed by as much as 50 ppb while differences over land were usually 10 ppb or less. Through another series of sensitivity studies that varied ozone precursor emissions, it was shown that a reduction of 50% NOx or VOC would lower the 60 ppb ozone exposure by up to 50 h per month in the remote forest regions over the northern Great Lakes. The implications of these results on future climate change and air quality in the region is discussed.

  15. Interannual variability of tropical cyclone activity and regional Hadley circulation over the Northeastern Pacific

    NASA Astrophysics Data System (ADS)

    Zhang, Gan; Wang, Zhuo

    2015-04-01

    The interannual variability of the regional Hadley circulation (HC) and tropical cyclone (TC) activity over the Northeastern Pacific (NEP) was investigated. The interannual variability of the HC in the NEP hurricane season is found dominated by a mode (M1EP) regulating the strength and meridional extent of the Intertropical Convergence Zone. M1EP has a more robust correlation with NEP TC activity than the El Niño-Southern Oscillation sea surface temperature indices. The strong correlation is attributed to the impacts of M1EP on environmental conditions. In addition, the leading mode of the Atlantic HC, which has an anticorrelation with M1EP, also strongly impacts NEP TC activity. The findings, together with Zhang and Wang (2013), highlight the role of the HC in controlling the variability of TC activity as well as the interbasin connection between the NEP and the Atlantic. The regional HC is thus recommended as a useful metric to benchmark models in simulating TC activity.

  16. A review of the global relationship among freshwater fish, autotrophic activity, and regional climate

    USGS Publications Warehouse

    Deines, Andrew M.; Bunnell, David B.; Rogers, Mark W.; Beard, T. Douglas; Taylor, William W.

    2015-01-01

    The relationship between autotrophic activity and freshwater fish populations is an important consideration for ecologists describing trophic structure in aquatic communities, fisheries managers tasked with increasing sustainable fisheries development, and fish farmers seeking to maximize production. Previous studies of the empirical relationships of autotrophic activity and freshwater fish yield have found positive relationships but were limited by small sample sizes, small geographic scopes, and the inability to compare patterns among many types of measurement techniques. Individual studies and reviews have also lacked consistent consideration of regional climate factors which may inform relationships between fisheries and autotrophic activity. We compiled data from over 700 freshwater systems worldwide and used meta-analysis and linear models to develop a comprehensive global synthesis between multiple metrics of autotrophic activity, fisheries, and climate indicators. Our results demonstrate that multiple metrics of fish (i.e., catch per unit effort, yield, and production) increase with autotrophic activity across a variety of fisheries. At the global scale additional variation in this positive relationship can be ascribed to regional climate differences (i.e., temperature and precipitation) across systems. Our results provide a method and proof-of-concept for assessing inland fisheries production at the global scale, where current estimates are highly uncertain, and may therefore inform the continued sustainable use of global inland fishery resources.

  17. The morphology of flare phenomena, magnetic fields, and electric currents in active regions. III - NOAA active region 6233 (1990 August)

    NASA Technical Reports Server (NTRS)

    De La Beaujardiere, J.-F.; Canfield, Richard C.; Leka, K. D.

    1993-01-01

    We investigate the spatial relationship between vertical electric currents and flare phenomena in NOAA Active Region 6233, which was observed 1990, August 28-31 at Mees Solar Observatory. The two flares studied are the 1N/M1.8 flare on August 28, 22:30 UT and the 1N/M1.6 flare on August 29, 20:35 UT. Using Stokes polarimetry we make magnetograms of the region and compute the vertical current density. Using H-alpha imaging spectroscopy we identify sites of intense nonthermal electron precipitation or of high coronal pressure. The precipitation in these flares is barely strong enough to be detectable. We find that both precipitation and high pressure tend to occur near vertical currents, but that neither phenomenon is cospatial with current maxima. In contrast with the conclusion of other authors, we argue that these observations do not support a current-interruption model for flares, unless the relevant currents are primarily horizontal. The magnetic morphology and temporal evolution of these flares suggest that an erupting filament model may be relevant, but this model does not explicitly predict the relationship between precipitation, high pressure, and vertical currents.

  18. Terahertz dual-wavelength quantum cascade laser based on GaN active region

    NASA Astrophysics Data System (ADS)

    Mirzaei, B.; Rostami, A.; Baghban, H.

    2012-03-01

    In this paper a novel terahertz (THz) quantum cascade laser (QCL) based on GaN/AlGaN quantum wells has been proposed, which emits at two widely separated wavelengths 33 and 52 μm simultaneously in a single active region. The large LO-phonon energy (˜90 meV), the ultrafast resonant phonon depopulation of the lower radiative levels, suppression of the electrons that escape to the continuum states and selective carrier injection and extraction all together lead to a considerable enhancement in the operating temperature of the structure. All calculations have been done at a temperature of 265 K. Moreover, similar behavior of the output optical powers is another remarkable feature, which makes both wavelengths useful for special applications.

  19. ON MAGNETIC ACTIVITY BAND OVERLAP, INTERACTION, AND THE FORMATION OF COMPLEX SOLAR ACTIVE REGIONS

    SciTech Connect

    McIntosh, Scott W.; Leamon, Robert J.

    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.

  20. The effects of activation temperature on physico-chemical characteristics of activated carbons derived from biomass wastes

    NASA Astrophysics Data System (ADS)

    Sutrisno, Bachrun; Hidayat, Arif

    2015-12-01

    This research focused on investigating in the effect of activation temperature on the physico-chemical properties of palm empty fruit bunch (PEFB) based activated carbon prepared by physical activation with carbon dioxide. The activation temperature was studied in the range of 400-800°C by keeping the activation temperature at 800°C for 120 min. It was found that the porous properties of activated carbon decreased with an increase in carbonization temperature. The activated carbons prepared at the highest activation temperature at 800°C and activation time of 120 min gave the activated carbon with the highest of BET surface area and pore volume of 938 m2/g and 0.4502 cm3/g, respectively

  1. Contribution of regional brain melanocortin receptor subtypes to elevated activity energy expenditure in lean, active rats

    PubMed Central

    Shukla, Charu; Koch, Lauren G.; Britton, Steven L.; Cai, Minying; Hruby, Victor J.; Bednarek, Maria; Novak, Colleen M.

    2015-01-01

    Physical activity and non-exercise activity thermogenesis (NEAT) are crucial factors accounting for individual differences in body weight, interacting with genetic predisposition. In the brain, a number of neuroendocrine intermediates regulate food intake and energy expenditure (EE); this includes the brain melanocortin (MC) system, consisting of melanocortin peptides as well as their receptors (MCR). MC3R and MC4R have emerged as critical modulators of EE and food intake. To determine how variance in MC signaling may underlie individual differences in physical activity levels, we examined behavioral response to MC receptor agonists and antagonists in rats that show high and low levels of physical activity and NEAT, that is, high- and low-capacity runners (HCR, LCR), developed by artificial selection for differential intrinsic aerobic running capacity. Focusing on the hypothalamus, we identified brain region-specific elevations in expression of MCR 3, 4, and also MC5R, in the highly active, lean HCR relative to the less active and obesity-prone LCR. Further, the differences in activity and associated EE as a result of MCR activation or suppression using specific agonists and antagonists were similarly region-specific and directly corresponded to the differential MCR expression patterns. The agonists and antagonists investigated here did not significantly impact food intake at the doses used, suggesting that the differential pattern of receptor expression may by more meaningful to physical activity than to other aspects of energy balance regulation. Thus, MCR-mediated physical activity may be a key neural mechanism in distinguishing the lean phenotype and a target for enhancing physical activity and NEAT. PMID:26404873

  2. Temperature Estimates for the Slow Slip Region on the Decollement Underlying the South Flank of Kilauea

    NASA Astrophysics Data System (ADS)

    Spinelli, G. A.

    2013-12-01

    Eleven slow slip events on the decollement beneath the south flank of Kilauea volcano have been documented geodetically since 1998 (Brooks et al., 2006; Montgomery-Brown et al., 2009; 2013). Tectonic tremor has not been observed associated with these events, in contrast to most slow slip events in subduction zones (Montgomery-Brown et al., 2013). The slow slip events occur on the decollement at ~8 km depth, and updip of the 'normal' earthquakes on the fault. Constraining temperatures on Kilauea's decollement allows comparisons between its slow slip events and those in subduction zones. Kilauea's slow slip events (~8 km depth) are significantly shallower than most subduction zone slow slip events. I estimate temperatures in a 2-D cross-section through the south flank of Kilauea by combining methods used in subduction zone thermal models (Wang et al., 1995) with elements of intrusion cooling models of volcanoes (e.g., Civetta et al., 2004). Temperatures in the cross-section are controlled by: 1) heat sources from friction on the decollement, radioactive decay, and volcanic activity, and 2) heat transport by conduction, advection of the volcanic pile to the southeast over the underlying oceanic lithosphere, and advective heat transport associated with groundwater flow. I examine the thermal effects of a range of effective friction coefficients on the fault from 0-0.2. I determine the potential effects of groundwater flow in the upper ~1-2 km of the onshore and near-offshore volcanic pile (e.g., Kauahikaua, 1993; Buttner and Huenges, 2003) on decollement temperatures. Finally, I examine how heat input from Kilauea volcano may result in higher decollement temperatures than at the same depth on plate boundary faults in subduction zones.

  3. Possible cause of enhancement of electron temperature in high electron density region in the dayside ionosphere

    NASA Astrophysics Data System (ADS)

    Kakinami, Yoshihiro; Watanabe, Shigeto

    2016-07-01

    When neutral atmosphere is ionized by solar EUV, energetic electrons named photoelectrons are emitted. The photoelectrons are primary heat source of electrons in the ionosphere in the daytime. The heating rate of electron by photoelectron is proportion to 0.97 power of electron density (Ne) while the heated electron is cooled through the Column collision with ions, the rate of which rate is square of Ne. Therefore, electron temperature (Te) decreases and approach ion temperature (Ti) with increase of Ne. Ions are also cooled through the collision with neutral spices. Finally, these temperatures (Te, Ti and Tn) show very similar values in high Ne region. However, Te enhancement with increase of Ne is found in the satellite observation at 600 km in the daytime ionosphere [Kakinami et al., 2011]. Similar Ti variation is also found around the magnetic dip equator [Kakinami et al., 2014]. One possible cause of the enhancement of Te is enhacement of Tn with increase Ne because both Ne and Tn increase with increase of solar irradiance flux, F10.7 [Lei et al., 2007]. However, since such the enhancements of Te are seen in any F10.7, it is hard to explain the phenomenon. In this paper, we present correlation between Te (Ti) and Ne obtained by the Incoherent Scatter radar at Jicamarca. The similar correlation, namely positive correlation of Te (Ti) with Ne in high Ne region are found above 300 km. Using the observations and Tn and neutral density calculated with MSIS, the Column collision cooling with ions, and inelastic collision cooling with neutral spices for electron are shown. The heat conduction along the magnetic field line is also estimated by using IRI model. Using these information, we discuss possible cause of the enhancement of Te in the high Ne region. References Kakinami et al. (2011), J. Geophys. Res., doi:10.1029/2011JA016905. Kakinami et al. (2014), J. Geophys. Res., 119, doi:10.1002/2014JA020302. Lei et al.(2007), J. Geophys. Res., doi:10.1029/2006JA012041.

  4. The SeaDataNet data products: regional temperature and salinity historical data collections

    NASA Astrophysics Data System (ADS)

    Simoncelli, Simona; Coatanoan, Christine; Bäck, Orjan; Sagen, Helge; Scoy, Serge; Myroshnychenko, Volodymyr; Schaap, Dick; Schlitzer, Reiner; Iona, Sissy; Fichaut, Michele

    2016-04-01

    Temperature and Salinity (TS) historical data collections covering the time period 1900-2013 were created for each European marginal sea (Arctic Sea, Baltic Sea, Black Sea, North Sea, North Atlantic Ocean and Mediterranean Sea) within the framework of SeaDataNet2 (SDN) EU-Project and they are now available as ODV collections through the SeaDataNet web catalog at http://sextant.ifremer.fr/en/web/seadatanet/. Two versions have been published and they represent a snapshot of the SDN database content at two different times: V1.1 (January 2014) and V2 (March 2015). A Quality Control Strategy (QCS) has been developped and continuously refined in order to improve the quality of the SDN database content and to create the best product deriving from SDN data. The QCS was originally implemented in collaboration with MyOcean2 and MyOcean Follow On projects in order to develop a true synergy at regional level to serve operational oceanography and climate change communities. The QCS involved the Regional Coordinators, responsible of the scientific assessment, the National Oceanographic Data Centers (NODC) and the data providers that, on the base of the data quality assessment outcome, checked and eventually corrected anomalies in the original data. The QCS consists of four main phases: 1) data harvesting from the central CDI; 2) file and parameter aggregation; 3) quality check analysis at regional level; 4) analysis and correction of data anomalies. The approach is iterative to facilitate the upgrade of SDN database content and it allows also the versioning of data products with the release of new regional data collections at the end of each QCS loop. SDN data collections and the QCS will be presented and the results summarized.

  5. Measured response of the equatorial thermospheric temperature to geomagnetic activity and solar flux changes

    NASA Technical Reports Server (NTRS)

    Biondi, M. A.; Meriwether, J. W., Jr.

    1985-01-01

    Fabry-Perot inteferometer determinations of thermospheric temperatures from 630.0-nm nightglow line-width measurements have been carried out for the period April-August 1983 from Arequipa, Peru (16.4-deg S, 71.5-deg W geographic; 4.4-deg S magnetic). The nightly variation of the thermospheric temperature T(n) measured on 62 nights is compared with MSIS model predictions and found to agree occasionally with the model but, on average, to exceed model predictions by about 180 K. The largest differences, 400-500 K, often occur during strongly increasing geomagnetic activity such as sudden commencements. The rapid increases in T(n) may result from energetic neutrals precipitating at low latitudes from the ring current or from energy carried to equatorial regions from high-latitude (auroral oval) heat sources by gravity waves and equatorward neutral winds.

  6. Region-specific sensitivity of anemophilous pollen deposition to temperature and precipitation.

    PubMed

    Donders, Timme H; Hagemans, Kimberley; Dekker, Stefan C; de Weger, Letty A; de Klerk, Pim; Wagner-Cremer, Friederike

    2014-01-01

    Understanding relations between climate and pollen production is important for several societal and ecological challenges, importantly pollen forecasting for pollinosis treatment, forensic studies, global change biology, and high-resolution palaeoecological studies of past vegetation and climate fluctuations. For these purposes, we investigate the role of climate variables on annual-scale variations in pollen influx, test the regional consistency of observed patterns, and evaluate the potential to reconstruct high-frequency signals from sediment archives. A 43-year pollen-trap record from the Netherlands is used to investigate relations between annual pollen influx, climate variables (monthly and seasonal temperature and precipitation values), and the North Atlantic Oscillation climate index. Spearman rank correlation analysis shows that specifically in Alnus, Betula, Corylus, Fraxinus, Quercus and Plantago both temperature in the year prior to (T-1), as well as in the growing season (T), are highly significant factors (TApril rs between 0.30 [P<0.05[ and 0.58 [P<0.0001]; TJuli-1 rs between 0.32 [P<0.05[ and 0.56 [P<0.0001]) in the annual pollen influx of wind-pollinated plants. Total annual pollen prediction models based on multiple climate variables yield R2 between 0.38 and 0.62 (P<0.0001). The effect of precipitation is minimal. A second trapping station in the SE Netherlands, shows consistent trends and annual variability, suggesting the climate factors are regionally relevant. Summer temperature is thought to influence the formation of reproductive structures, while temperature during the flowering season influences pollen release. This study provides a first predictive model for seasonal pollen forecasting, and also aides forensic studies. Furthermore, variations in pollen accumulation rates from a sub-fossil peat deposit are comparable with the pollen trap data. This suggests that high frequency variability pollen records from natural archives reflect

  7. Region-Specific Sensitivity of Anemophilous Pollen Deposition to Temperature and Precipitation

    PubMed Central

    Donders, Timme H.; Hagemans, Kimberley; Dekker, Stefan C.; de Weger, Letty A.; de Klerk, Pim; Wagner-Cremer, Friederike

    2014-01-01

    Understanding relations between climate and pollen production is important for several societal and ecological challenges, importantly pollen forecasting for pollinosis treatment, forensic studies, global change biology, and high-resolution palaeoecological studies of past vegetation and climate fluctuations. For these purposes, we investigate the role of climate variables on annual-scale variations in pollen influx, test the regional consistency of observed patterns, and evaluate the potential to reconstruct high-frequency signals from sediment archives. A 43-year pollen-trap record from the Netherlands is used to investigate relations between annual pollen influx, climate variables (monthly and seasonal temperature and precipitation values), and the North Atlantic Oscillation climate index. Spearman rank correlation analysis shows that specifically in Alnus, Betula, Corylus, Fraxinus, Quercus and Plantago both temperature in the year prior to (T-1), as well as in the growing season (T), are highly significant factors (TApril rs between 0.30 [P<0.05[ and 0.58 [P<0.0001]; TJuli-1 rs between 0.32 [P<0.05[ and 0.56 [P<0.0001]) in the annual pollen influx of wind-pollinated plants. Total annual pollen prediction models based on multiple climate variables yield R2 between 0.38 and 0.62 (P<0.0001). The effect of precipitation is minimal. A second trapping station in the SE Netherlands, shows consistent trends and annual variability, suggesting the climate factors are regionally relevant. Summer temperature is thought to influence the formation of reproductive structures, while temperature during the flowering season influences pollen release. This study provides a first predictive model for seasonal pollen forecasting, and also aides forensic studies. Furthermore, variations in pollen accumulation rates from a sub-fossil peat deposit are comparable with the pollen trap data. This suggests that high frequency variability pollen records from natural archives reflect

  8. High resolution studies of complex solar active regions

    NASA Astrophysics Data System (ADS)

    Deng, Na

    Flares and Coronal Mass Ejections (CMEs) are energetic events, which can even impact the near-Earth environment and are the principal source of space weather. Most of them originate in solar active regions. The most violent events are produced in sunspots with a complex magnetic field topology. Studying their morphology and dynamics is helpful in understanding the energy accumulation and release mechanisms for flares and CMEs, which are intriguing problems in solar physics. The study of complex active regions is based on high-resolution observations from space missions and new instruments at the Big Bear Solar Observatory (BBSO). Adaptive optics (AO) in combination with image restoration techniques (speckle masking imaging) can achieve improved image quality and a spatial resolution (about 100 km on the solar surface) close to the diffraction limit of BBSO's 65 cm vacuum telescope. Dopplergrams obtained with a two-dimensional imaging spectrometer combined with horizontal flow maps derived with Local Correlation Tracking (LCT) provide precise measurements of the three-dimensional velocity field in sunspots. Magnetic field measurements from ground- and space-based instruments complement these data. At the outset of this study, the evolution and morphology of a typical round sunspot are described in some detail. The sunspot was followed from disk center to the limb, thus providing some insight into the geometry of the magnetic flux system. Having established a benchmark for a stable sunspot, the attention is turned to changes of the sunspot structure associated with flares and CMEs. Rapid penumbral decay and the strengthening of sunspot umbrae are manifestations of photospheric magnetic field changes after a flare. These sudden intensity changes are interpreted as a result of magnetic reconnection during the flare, which causes the magnetic field lines to be turned from more inclined to more vertical. Strong photospheric shear flows along the flaring magnetic

  9. Insolation and Resulting Surface Temperatures of Study Regions on the Moon and Implications for Mercury

    NASA Astrophysics Data System (ADS)

    Bauch, Karin E.; Hiesinger, Harald

    2010-05-01

    The imaging spectrometer MERTIS (Mercury Radiometer and Thermal Infrared Spectrometer) is part of the payload of ESA's BepiColombo mission, which is scheduled for launch in 2014 (Hiesinger et al., 2010). The instrument consists of an IR-spectrometer and radiometer, which observe the surface in the wavelength range of 7-14 and 7-40µm, respectively. The four scientific objectives are to a) study Mercury's surface composition, b) identify rock-forming minerals, c) globally map the surface mineralogy and d) study surface temperature and thermal inertia (Hiesinger et al., 2010; Helbert et al., 2005). Previous studies of the lunar surface have shown that thermal emission contributes to the observed signal from the surface and can influence the spectral characteristics, e.g. the depth of absorption bands (e.g. Clark, 2009; Pieters et al., 2009; Sunshine et al., 2009). Therefore accurate knowledge of the solar insolation and resulting thermal variations is needed. In order to calculate insolation and surface temperatures, we use a numerical model which has been described by Bauch et al. (2009). Surface temperatures are depending on the surface and subsurface bulk thermophysical properties, such as bulk density, heat capacity, thermal conductivity, emissivity, and albedo. Topography also influences surface temperatures, as it changes the angle of solar incidence, but also leads to shadowed areas, e.g. the floors of polar craters. The model solves the one-dimensional heat transfer equation, based on a depth and temperature dependent thermal inertia. The surface boundary condition is based on the energy balance relation; the energy entering a surface equals the energy leaving the surface. In addition to the direct solar insolation, reflectance and scattering from adjacent surface regions also influence the surface temperatures. In preparation of the MERTIS experiment, we performed detailed thermal models of the lunar surface, which we extrapolated to Mercury. For our

  10. Rethinking the longitudinal stream temperature paradigm: region-wide comparison of thermal infrared imagery reveals unexpected complexity of river temperatures

    USGS Publications Warehouse

    Fullerton, Aimee H.; Torgersen, Christian; Lawler, Joshua J.; Faux, Russell N.; Steel, E. Ashley; Beechie, Timothy J.; Ebersole, Joseph L.; Leibowitz, Scott J.

    2015-01-01

    Prevailing theory suggests that stream temperature warms asymptotically in a downstream direction, beginning at the temperature of the source in the headwaters and leveling off downstream as it converges to match meteorological conditions. However, there have been few empirical examples of longitudinal patterns of temperature in large rivers due to a paucity of data. We constructed longitudinal thermal profiles (temperature versus distance) for 53 rivers in the Pacific Northwest (USA) using an extensive dataset of remotely sensed summertime river temperatures and classified each profile into one of five patterns of downstream warming: asymptotic (increasing then flattening), linear (increasing steadily), uniform (not changing), parabolic (increasing then decreasing), or complex (not fitting other classes). We evaluated (1) how frequently profiles warmed asymptotically downstream as expected, and (2) whether relationships between river temperature and common hydroclimatic variables differed by profile class. We found considerable diversity in profile shape, with 47% of rivers warming asymptotically, and 53% having alternative profile shapes. Water temperature did not warm substantially over the course of the river for coastal parabolic and uniform profiles, and for some linear and complex profiles. Profile classes showed no clear geographical trends. The degree of correlation between river temperature and hydroclimatic variables differed among profile classes, but there was overlap among classes. Water temperature in rivers with asymptotic or parabolic profiles was positively correlated with August air temperature, tributary temperature and velocity, and negatively correlated with elevation, August precipitation, gradient, and distance upstream. Conversely, associations were less apparent in rivers with linear, uniform, or complex profiles. Factors contributing to the unique shape of parabolic profiles differed for coastal and inland rivers, where downstream cooling

  11. Zebrafish temperature selection and synchronization of locomotor activity circadian rhythm to ahemeral cycles of light and temperature.

    PubMed

    López-Olmeda, Jose Fernando; Sánchez-Vázquez, Francisco Javier

    2009-02-01

    In addition to light cycles, temperature cycles are among the most important synchronizers in nature. Indeed, both clock gene expression and circadian activity rhythms entrain to thermocycles. This study aimed to extend our knowledge of the relative strength of light and temperature as zeitgebers for zebrafish locomotor activity rhythms. When the capacity of a 24:20 degrees C (thermophase:cryophase, referred to as TC) thermocycle to synchronize activity rhythms under LL was evaluated, it was found that most groups (78%) synchronized to these conditions. Under LD, when zebrafish were allowed to select the water temperature (24 degrees C vs. 20 degrees C), most fish selected the higher temperature and showed diurnal activity, while a small (25%) percentage of fish that preferred the lower temperature displayed nocturnal activity. Under conflicting LD and TC cycles, fish showed diurnal activity when the zeitgebers were in phase or in antiphase, with a high percentage of activity displayed around dawn and dusk (22% and 34% of the total activity for LD/TC and LD/CT, respectively). Finally, to test the relative strength of each zeitgeber, fish were subjected to ahemeral cycles of light (T=25 h) and temperature (T=23 h). Zebrafish synchronized mostly to the light cycle, although they displayed relative coordination, as their locomotor activity increased when light and thermophase coincided. These findings show that although light is a stronger synchronizer than temperature, TC cycles alone can entrain circadian rhythms and interfere in their light synchronization, suggesting the existence of both light- and temperature-entrainable oscillators that are weakly coupled.

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

    SciTech Connect

    Mulu-Moore, Fana M.; Winebarger, Amy R.; Warren, Harry P.

    2011-11-20

    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.

  13. Electric, Magnetic and Ionospheric Survey of Seismically Active Regions with SWARM

    NASA Astrophysics Data System (ADS)

    Echim, Marius M.; Moldovan, Iren; Voiculescu, Mirela; Balasis, George; Lichtenberger, Janos; Heilig, Balazs; Kovacs, Peter

    2014-05-01

    We present a project devoted to the scientific exploitation of SWARM multi-point measurements of the magnetic and electric field, of the electron temperature and density in the ionosphere. These data provide unique opportunities to study in-situ and remotely the electromagnetic and plasma variability due to ionospheric forcing from above and below. The project "Electric, Magnetic and Ionospheric Survey of Seismically Active Regions with SWARM (EMISSARS)" focus on coordinated studies between SWARM and ground based observatories to survey electromagnetic and ionospheric variability at medium latitudes and look for possible correlations with the seismic activity in central Europe. The project is coordinated by the Institute for Space Sciences (INFLPR-ISS) and the National Institute for Earth Physics (INFP) in Bucharest, Romania. In addition to SWARM data the project benefits from support of dedicated ground based measurements provided by the MEMFIS network coordinated by INFP, the MM100 network of magnetic observatories coordinated by the Geological and Geophysical Institute of Hungary (MFGI) in Budapest. Seismic data are provided by INFP and the European Mediterranean Seismological Center. The mission of the project is to monitor from space and from ground the ionospheric and electromagnetic variability during time intervals prior, during and after seismic activity in (i) the seismic active regions of the central Europe and (ii) in regions unaffected by the seismic activity. The latter will provide reference measurements, free from possible seismogenic signals. The scientific objectives of the project are: (1) Observation of electric, magnetic and ionospheric (electron temperature, density) variability in the ionosphere above or in the close vicinity of seismic active regions, in conjunction with ground based observations from dedicated networks; (2) Investigation of the coupling between the litosphere - atmosphere - ionosphere, during Earthquakes; (3) Quantitative

  14. Apparent and Intrinsic Evolution of Active Region Upflows

    NASA Astrophysics Data System (ADS)

    Baker, Deborah; Janvier, Miho; Démoulin, Pascal; Mandrini, Cristina H.

    2017-04-01

    We analyze the evolution of Fe xii coronal plasma upflows from the edges of ten active regions (ARs) as they cross the solar disk using the Hinode Extreme Ultraviolet Imaging Spectrometer (EIS) to do this. Confirming the results of Démoulin et al. ( Sol. Phys. 283, 341, 2013), we find that for each AR there is an observed long-term evolution of the upflows. This evolution is largely due to the solar rotation that progressively changes the viewpoint of dominantly stationary upflows. From this projection effect, we estimate the unprojected upflow velocity and its inclination to the local vertical. AR upflows typically fan away from the AR core by 40° to nearly vertical for the following polarity. The span of inclination angles is more spread out for the leading polarity, with flows angled from -29° (inclined toward the AR center) to 28° (directed away from the AR). In addition to the limb-to-limb apparent evolution, we identify an intrinsic evolution of the upflows that is due to coronal activity, which is AR dependent. Furthermore, line widths are correlated with Doppler velocities only for the few ARs with the highest velocities. We conclude that for the line widths to be affected by the solar rotation, the spatial gradient of the upflow velocities must be large enough such that the line broadening exceeds the thermal line width of Fe xii. Finally, we find that upflows occurring in pairs or multiple pairs are a common feature of ARs observed by Hinode/EIS, with up to four pairs present in AR 11575. This is important for constraining the upflow-driving mechanism as it implies that the mechanism is not local and does not occur over a single polarity. AR upflows originating from reconnection along quasi-separatrix layers between overpressure AR loops and neighboring underpressure loops is consistent with upflows occurring in pairs, unlike other proposed mechanisms that act locally in one polarity.

  15. Seismic activity of the San Francisco Bay region

    USGS Publications Warehouse

    Bakun, W.H.

    1999-01-01

    Moment magnitude M with objective confidence-level uncertainties are estimated for felt San Francisco Bay region earthquakes using Bakun and Wentworth's (1997) analysis strategy for seismic intensity observations. The frequency-magnitude distribution is well described for M ???5.5 events since 1850 by a Gutenberg-Richter relation with a b-value of 0.90. The seismic moment rate ??M0/yr since 1836 is 2.68 X 1018 N-m/yr (95% confidence range = 1.29 X 1018 N-m/yr to 4.07 X 1018 N-m/yr); the seismic moment rate since 1850 is nearly the same. ??M0/yr in the 56 years before 1906 is about 10 times that in the 70 years after 1906. In contrast, ??M0/yr since 1977 is about equal that in the 56 years before 1906. 80% (1?? = 14%) of the plate-motion moment accumulation rate is available for release in earthquakes. The historical ??M0/yr and the portion of the plate-motion moment accumulation rate available for release in earthquakes are used in a seismic cycle model to estimate the rate of seismic activity in the twenty-first century. High and low rates of future seismic activity are both permissible given the range of possible seismic-cycle recurrence times T and the uncertainties in the historical ??M0 and in the percentage of plate motion available for release in earthquakes. If the historical seismic moment rate is not greater than the estimated 2.68 X 1018 N-m/yr and the percentage of the plate-motion moment accumulation available for release in earthquakes is not less than the estimated 80%, then for all T, the rate of seismic moment release from now until the next 1906-sized shock will be comparable to the rate from 1836 to 1905 when M 6 1/2 shocks occurred every 15 to 20 years.

  16. FIP BIAS EVOLUTION IN A DECAYING ACTIVE REGION

    SciTech Connect

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

    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.

  17. Dominance of pollutant aerosols over an urban region and its impact on boundary layer temperature profile

    NASA Astrophysics Data System (ADS)

    Talukdar, Shamitaksha; Jana, Soumyajyoti; Maitra, Animesh

    2017-01-01

    Collocated measurements of aerosol optical depth (AOD) and black carbon at different wavelengths over Kolkata, an urban region in eastern India, have been used to calculate aerosol single-scattering albedo (SSA). The wavelength dependence of SSA and AOD has been presented to discriminate the aerosol types over this highly populated metropolitan area. The spectral pattern shows that SSA decreases with wavelength for most of the time in a year and corresponding Ångström coefficient is greater than unity. These optical properties indicate the dominance of fine-mode pollutant particles over the city. The temperature lapse rate profile within the surface boundary layer has been found to be significantly influenced by the heating effect of fine-mode pollutants, and consequently, the growth of the convective processes in the lower troposphere is notably affected. In addition, a back trajectory analysis has also been presented to indicate that transported air masses can have significant impact on spectral pattern of SSA.

  18. Projection of temperature and heat waves for Africa with an ensemble of CORDEX Regional Climate Models

    NASA Astrophysics Data System (ADS)

    Dosio, Alessandro

    2016-09-01

    The most severe effects of global warning will be related to the frequency and severity of extreme events. We provide an analysis of projections of temperature and related extreme events for Africa based on a large ensemble of Regional Climate Models from the COordinated Regional climate Downscaling EXperiment (CORDEX). Results are presented not only by means of widely used indices but also with a recently developed Heat Wave Magnitude Index-daily (HWMId), which takes into account both heat wave duration and intensity. Results show that under RCP8.5, warming of more than 3.5 °C is projected in JFM over most of the continent, whereas in JAS temperatures over large part of Northern Africa, the Sahara and the Arabian peninsula are projected to increase up to 6 °C. Large increase in in the number of warm days (Tx90p) is found over sub equatorial Africa, with values up to more than 90 % in JAS, and more than 80 % in JFM over e.g., the gulf of Guinea, Central African Republic, South Sudan and Ethiopia. Changes in Tn90p (warm nights) are usually larger, with some models projecting Tn90p reaching 95 % starting from around 2060 even under RCP4.5 over the Gulf of Guinea and the Sahel. Results also show that the total length of heat spells projected to occur normally (i.e. once every 2 years) under RCP8.5 may be longer than those occurring once every 30 years under the lower emission scenario. By employing the recently developed HWMId index, it is possible to investigate the relationship between heat wave length ad intensity; in particular it is shown that very intense heat waves such as that occurring over the Horn of Africa may have values of HWMId larger than that of longer, but relatively weak, heat waves over West Africa.

  19. Simulation of temperature regime of the Moscow region in XXI century

    NASA Astrophysics Data System (ADS)

    Konstantinov, Pavel; Kislov, Alexander

    2010-05-01

    In view of growing public attention to modern ecological and climatic problems, one of the most important problems of meteorology and climatology is to develop realistic scenarios of future climatic changes. The modern general circulation (GCM) and regional atmospheric (RM) models allow to reproduce meteorological fields with the spatial grid resolution about 50×50 and 5x5 km, respectively. Such model resolution is, unfortunately, not allow to enough adequately describing the climatic condition of the cities. Taking into account big differences of meteorological conditions in- and outside of the cities the prediction uncertainties provided by GCM and RM models for cities may be relatively large. Within the framework of this study the simple model allowing to reproduce climatic conditions of the city was developed. It was applied to predict temperature regime in Moscow region in Russia for the middle and the end of XXI century. It based on the data provided by GCM and RM models and allows to predict meteorological condition with spatial resolution about 0,5 km×0,5 km. In the study it was shown that the thermal regime of Moscow area as well as Moscow surrounding areas are well reproduced by developed model. The model allows to describe realistically a spatial heterogeneity of temperature in July both under modern and future climatic conditions. It was also shown, that the area of "warm islands" in Moscow is characterized by very high probability of extreme event occurrency. In July 2050 the probability of this occurrency of will be significantly higher than at present The same thing we can say about the climate of 2100. Thus, in the near future the climate of Moscow during the summer period will be hotter, and it will result in different environmental problems and increased energy demand.

  20. SIMULATION OF THE FORMATION OF A SOLAR ACTIVE REGION

    SciTech Connect

    Cheung, M. C. M.; Title, A. M.; Rempel, M.; Schuessler, M.

    2010-09-01

    We present a radiative magnetohydrodynamics simulation of the formation of an active region (AR) on the solar surface. The simulation models the rise of a buoyant magnetic flux bundle from a depth of 7.5 Mm in the convection zone up into the solar photosphere. The rise of the magnetic plasma in the convection zone is accompanied by predominantly horizontal expansion. Such an expansion leads to a scaling relation between the plasma density and the magnetic field strength such that B {proportional_to} rhov{sup 1/2}. The emergence of magnetic flux into the photosphere appears as a complex magnetic pattern, which results from the interaction of the rising magnetic field with the turbulent convective flows. Small-scale magnetic elements at the surface first appear, followed by their gradual coalescence into larger magnetic concentrations, which eventually results in the formation of a pair of opposite polarity spots. Although the mean flow pattern in the vicinity of the developing spots is directed radially outward, correlations between the magnetic field and velocity field fluctuations allow the spots to accumulate flux. Such correlations result from the Lorentz-force-driven, counterstreaming motion of opposite polarity fragments. The formation of the simulated AR is accompanied by transient light bridges between umbrae and umbral dots. Together with recent sunspot modeling, this work highlights the common magnetoconvective origin of umbral dots, light bridges, and penumbral filaments.

  1. Plasma Composition in a Sigmoidal Anemone Active Region

    NASA Astrophysics Data System (ADS)

    Baker, D.; Brooks, D. H.; Démoulin, P.; van Driel-Gesztelyi, L.; Green, L. M.; Steed, K.; Carlyle, J.

    2013-11-01

    Using spectra obtained by the EUV Imaging Spectrometer (EIS) instrument onboard Hinode, we present a detailed spatially resolved abundance map of an active region (AR)-coronal hole (CH) complex that covers an area of 359'' × 485''. The abundance map provides first ionization potential (FIP) bias levels in various coronal structures within the large EIS field of view. Overall, FIP bias in the small, relatively young AR is 2-3. This modest FIP bias is a consequence of the age of the AR, its weak heating, and its partial reconnection with the surrounding CH. Plasma with a coronal composition is concentrated at AR loop footpoints, close to where fractionation is believed to take place in the chromosphere. In the AR, we found a moderate positive correlation of FIP bias with nonthermal velocity and magnetic flux density, both of which are also strongest at the AR loop footpoints. Pathways of slightly enhanced FIP bias are traced along some of the loops connecting opposite polarities within the AR. We interpret the traces of enhanced FIP bias along these loops to be the beginning of fractionated plasma mixing in the loops. Low FIP bias in a sigmoidal channel above the AR's main polarity inversion line, where ongoing flux cancellation is taking place, provides new evidence of a bald patch magnetic topology of a sigmoid/flux rope configuration.

  2. Optical Properties of Active Regions in Terahertz Quantum Cascade Lasers

    NASA Astrophysics Data System (ADS)

    Dyksik, M.; Motyka, M.; Rudno-Rudziński, W.; Sęk, G.; Misiewicz, J.; Pucicki, D.; Kosiel, K.; Sankowska, I.; Kubacka-Traczyk, J.; Bugajski, M.

    2016-07-01

    In this work, AlGaAs/GaAs superlattice, with layers' sequence and compositions imitating the active and injector regions of a quantum cascade laser designed for emission in the terahertz spectral range, was investigated. Three independent absorption-like optical spectroscopy techniques were employed in order to study the band structure of the minibands formed within the conduction band. Photoreflectance measurements provided information about interband transitions in the investigated system. Common transmission spectra revealed, in the target range of intraband transitions, mainly a number of lines associated with the phonon-related processes, including two-phonon absorption. In contrast, differential transmittance realized by means of Fourier-transform spectroscopy was utilized to probe the confined states of the conduction band. The obtained energy separation between the second and third confined electron levels, expected to be predominantly contributing to the lasing, was found to be ~9 meV. The optical spectroscopy measurements were supported by numerical calculations performed in the effective mass approximation and XRD measurements for layers' width verification. The calculated energy spacings are in a good agreement with the experimental values.

  3. Plasma composition in a sigmoidal anemone active region

    SciTech Connect

    Baker, D.; Van Driel-Gesztelyi, L.; Green, L. M.; Carlyle, J.; Brooks, D. H.; Démoulin, P.; Steed, K.

    2013-11-20

    Using spectra obtained by the EUV Imaging Spectrometer (EIS) instrument onboard Hinode, we present a detailed spatially resolved abundance map of an active region (AR)-coronal hole (CH) complex that covers an area of 359'' × 485''. The abundance map provides first ionization potential (FIP) bias levels in various coronal structures within the large EIS field of view. Overall, FIP bias in the small, relatively young AR is 2-3. This modest FIP bias is a consequence of the age of the AR, its weak heating, and its partial reconnection with the surrounding CH. Plasma with a coronal composition is concentrated at AR loop footpoints, close to where fractionation is believed to take place in the chromosphere. In the AR, we found a moderate positive correlation of FIP bias with nonthermal velocity and magnetic flux density, both of which are also strongest at the AR loop footpoints. Pathways of slightly enhanced FIP bias are traced along some of the loops connecting opposite polarities within the AR. We interpret the traces of enhanced FIP bias along these loops to be the beginning of fractionated plasma mixing in the loops. Low FIP bias in a sigmoidal channel above the AR's main polarity inversion line, where ongoing flux cancellation is taking place, provides new evidence of a bald patch magnetic topology of a sigmoid/flux rope configuration.

  4. THE ORIGIN OF NET ELECTRIC CURRENTS IN SOLAR ACTIVE REGIONS

    SciTech Connect

    Dalmasse, K.; Kliem, B.; Török, T.

    2015-09-01

    There is a recurring question in solar physics regarding 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. Other sources of AR currents are photospheric horizontal flows. Our aim is to determine the conditions for the occurrence of net versus 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 direct and 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. We demonstrate that neutralized currents are in general produced only in the absence of magnetic shear at the photospheric polarity inversion line—a special condition that is rarely observed. We conclude that  photospheric flows, as magnetic flux emergence, can build up net currents in the solar atmosphere, in agreement with recent observations. These results thus provide support for eruption models based on pre-eruption magnetic fields that possess a net coronal current.

  5. Magnetic Separatrix as the Source Region of the Plasma Supply for an Active-region Filament

    NASA Astrophysics Data System (ADS)

    Zou, P.; Fang, C.; Chen, P. F.; Yang, K.; Cao, Wenda

    2017-02-01

    Solar filaments can be formed via chromospheric evaporation followed by condensation in the corona or by the direct injection of cool plasma from the chromosphere to the corona. We here confirm with high-resolution Hα data observed by the 1.6 m New Solar Telescope of the Big Bear Solar Observatory on 2015 August 21 that an active-region filament is maintained by the continuous injection of cold chromospheric plasma. We find that the filament is rooted along a bright ridge in Hα, which corresponds to the intersection of a magnetic quasi-separatrix layer with the solar surface. This bright ridge consists of many small patches whose sizes are comparable to the width of the filament threads. It is found that upflows originate from the brighter patches of the ridge, whereas the downflows move toward the weaker patches of the ridge. The whole filament is composed of two opposite-direction streams, implying that longitudinal oscillations are not the only cause of the counterstreamings, and unidirectional siphon flows with alternative directions are another possibility.

  6. Temperature and salts effects on the peptidase activities of the recombinant metallooligopeptidases neurolysin and thimet oligopeptidase.

    PubMed

    Oliveira, Vitor; Gatti, Reynaldo; Rioli, Vanessa; Ferro, Emer S; Spisni, Alberto; Camargo, Antonio C M; Juliano, Maria A; Juliano, Luiz

    2002-09-01

    We report the recombinant neurolysin and thimet oligopeptidase (TOP) hydrolytic activities towards internally quenched fluorescent peptides derived from the peptide Abz-GGFLRRXQ-EDDnp (Abz, ortho-aminobenzoicacid; EDDnp, N-(2,4-dinitrophenyl) ethylenediamine), in which X was substituted by 11 different natural amino acids. Neurolysin hydrolyzed these peptides at R-R or at R-X bonds, and TOP hydrolyzed at R-R or L-R bonds, showing a preference to cleave at three or four amino acids from the C-terminal end. The kinetic parameters of hydrolysis and the variations of the cleavage sites were evaluated under different conditions of temperature and salt concentration. The relative amount of cleavage varied with the nature of the substitution at the X position as well as with temperature and NaCl concentration. TOP was activated by all assayed salts in the range 0.05-0.2 m for NaCl, KCl, NH4Cl and NaI, and 0.025-0.1 m for Na2SO4. Concentration higher than 0.2 N NH4Cl and NaI reduced TOP activity, while 0.5 N or higher concentration of NaCl, KCl and Na2SO4 increased TOP activity. Neurolysin was strongly activated by NaCl, KCl and Na2SO4, while NH4Cl and NaI have very modest effect. High positive values of enthalpy (DeltaH*) and entropy (DeltaS*) of activation were found together with an unusual temperature dependence upon the hydrolysis of the substrates. The effects of low temperature and high NaCl concentration on the hydrolytic activities of neurolysin and TOP do not seem to be a consequence of large secondary structure variation of the proteins, as indicated by the far-UV CD spectra. However, the modulation of the activities of the two oligopeptidases could be related to variations of conformation, in limited regions of the peptidases, enough to modify their activities.

  7. Grueneberg Glomeruli in the Olfactory Bulb are Activated by Odorants and Cool Temperature.

    PubMed

    Bumbalo, Rosolino; Lieber, Marilena; Schroeder, Lisa; Polat, Yasemin; Breer, Heinz; Fleischer, Joerg

    2016-08-03

    Neurons of the Grueneberg ganglion respond to cool temperatures as well as to distinct odorants and extend axonal processes to the olfactory bulb of the brain. Analyses of transgenic mice, in which Grueneberg ganglion neurons and their axons are labeled, revealed that these axons innervated nine distinct glomeruli distributed in a characteristic topographical pattern in dorsal, lateral, ventral, and medial regions of rather posterior areas in the bulb. To assess activation of these glomeruli (hereinafter designated as Grueneberg glomeruli) upon stimulation of Grueneberg ganglion neurons, mice were exposed to the odorant 2,3-dimethylpyrazine (2,3-DMP) and the expression of the activity-dependent marker c-Fos in juxtaglomerular cells of the relevant glomeruli was monitored. It was found that all of these glomeruli were activated, irrespective of their localization in the bulb. To verify that the activation of juxtaglomerular cells in Grueneberg glomeruli was indeed based on stimulation of Grueneberg ganglion neurons, the 2,3-DMP-induced responses in these glomeruli were investigated in mice lacking the cyclic nucleotide-gated channel CNGA3 which is critical for chemo- and thermosensory signal transduction in Grueneberg ganglion neurons. This approach revealed that elimination of CNGA3 led to a reduction of the odorant-induced activity in Grueneberg glomeruli, indicating that the activation of these glomeruli is based on a preceding stimulation of the Grueneberg ganglion. Analyzing whether Grueneberg glomeruli in the bulb might also process thermosensory information, it was found that upon exposure to coolness, Grueneberg glomeruli were activated. Investigating mice lacking CNGA3, the activation of these glomeruli by cool temperatures was attenuated.

  8. Evening physical activity alters wrist temperature circadian rhythmicity.

    PubMed

    Rubio-Sastre, Patricia; Gómez-Abellán, Purificación; Martinez-Nicolas, Antonio; Ordovás, José María; Madrid, Juan Antonio; Garaulet, Marta

    2014-03-01

    The adequate time to perform physical activity (PA) to maintain optimal circadian system health has not been defined. We studied the influence of morning and evening PA on circadian rhythmicity in 16 women with wrist temperature (WT). Participants performed controlled PA (45 min continuous-running) during 7 days in the morning (MPA) and evening (EPA) and results were compared with a no-exercise-week (C). EPA was characterized by a lower amplitude (evening: 0.028 ± 0.01 °C versus control: 0.038 ± 0.016 °C; p < 0.05) less pronounced second-harmonic (power) (evening: 0.41 ± 0.47 versus morning: 1.04 ± 0.59); and achrophase delay (evening: 06:35 ± 02:14 h versus morning: 04:51 ± 01:11 h; p < 0.05) as compared to MPA and C. Performing PA in the late evening might not be as beneficial as in the morning.

  9. Seasonal Change Detection and Attribution of Surface Temperature changes over Interior Peninsular Region of India

    NASA Astrophysics Data System (ADS)