Sample records for day-to-day temperature variability

  1. Day-to-day variations of temperature in Texas 

    E-print Network

    Breese, Richard Preston

    1968-01-01

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  2. Day-to-day Variability in Nap Duration Predicts Medical Morbidity in Older Adults

    PubMed Central

    Dautovich, Natalie D.; Kay, Daniel B.; Perlis, Michael L.; Dzierzewski, Joseph M.; Rowe, Meredeth A.; McCrae, Christina S.

    2014-01-01

    Objective The objectives for the present study were to: 1) examine within-person variability of nap duration and 2) assess how variability in nap duration is related to the number of health conditions in a sample of older adults. For highly variable behaviors such as sleep, it is important to consider fluctuations within the person instead of solely comparing averages of behaviors across persons. Methods Data were drawn from a previous study examining sleep in 103 community-dwelling older adults. Subjective estimates of napping behavior were obtained from sleep diaries and objective estimates of napping behavior were obtained using actigraphy. Both measures were collected for 14 consecutive days. The sampled data were aggregated in terms of: 1) average daily time spent napping and 2) average within-person fluctuations in daily nap duration. The health measure consisted of the number of self-reported health conditions. Results Both the objective and subjective measures revealed that there was considerable day-to-day fluctuation in nap duration and that variability in nap duration, not mean duration, uniquely predicted the number of health conditions, [b=.03, b*=.26, t(100)= 2.71, p = .01]. Conclusions Duration of napping in the elderly is a highly variable behavior, fluctuating as much within- as between-person. Further, variability in nap duration from day-to-day is predictive of greater medical morbidity, suggesting that clinicians should assess for inconsistencies in nap behavior in addition to duration, frequency, and timing. PMID:22369491

  3. Modelling F2-layer seasonal trends and day-to-day variability driven by coupling with the lower atmosphere

    Microsoft Academic Search

    M. Mendillo; H. Rishbeth; R. G. Roble; J. Wroten

    2002-01-01

    This paper presents results from the TIME-GCM-CCM3 thermosphere–ionosphere–lower atmosphere flux-coupled model, and investigates how well the model simulates known F2-layer day\\/night and seasonal behaviour and patterns of day-to-day variability at seven ionosonde stations. Of the many possible contributors to F2-layer variability, the present work includes only the influence of ‘meteorological’ disturbances transmitted from lower levels in the atmosphere, solar and

  4. Observations of day-to-day variability in precursor signatures to equatorial F-region plasma depletions

    Microsoft Academic Search

    P. R. Fagundes; Y. Sahai; I. S. Batista; M. A. Abdu; J. A. Bittencourt; H. Takahashi

    1999-01-01

    In December 1995, a campaign was carried out to study the day-to-day variability in precursor signatures to large-scale ionospheric F-region plasma irregularities, using optical diagnostic techniques, near the magnetic equator in the Brazilian sector. Three instruments were operated simultaneously: (a) an all-sky (180° field of view) imaging system for observing the OI 630 nm nightglow emission at Alcântara (2.5°S, 44.4°W);

  5. Day-to-day body-image states: prospective predictors of intra-individual level and variability.

    PubMed

    Rudiger, Jonathan A; Cash, Thomas F; Roehrig, Megan; Thompson, J Kevin

    2007-03-01

    Most body-image research has focused on the trait level of body-image evaluation, often neglecting the momentary fluctuations many people experience in everyday life. The present prospective study investigated whether theory-relevant body-image measures, perfectionistic self-presentation, and eating attitudes would predict average day-to-day body-image levels and their intra-individual variability. A convenience sample consisted of 121 women from two universities. In Phase 1 of the study, participants completed an online battery of selected body-image and personality questionnaires. In Phase 2, participants went online to complete the dependent measure, the Body Image States Scale, once per evening over 10 days. As hypothesized, more favorable body-image state levels were associated with less investment in appearance for self-worth, less body-image disturbance, fewer body-image cognitive distortions, less disturbed eating attitudes, and lower body mass. Moreover, greater day-to-day body-image variability was predicted by greater psychological investment in appearance, more body-image cognitive distortions, and higher perfectionistic self-presentation. Implications and future directions for research are discussed. PMID:18089247

  6. NPR: Day to Day

    NSDL National Science Digital Library

    Hosted by award-winning National Public Radio (NPR) correspondent Alex Chadwick, Day to Day is a way for regular NPR listeners to listen to smart news coverage during the middle of the day or during their lunch-hour. Fortunately, Day to Day is available online, complete with an archive dating back to January 2003. Produced in the NPR West office in Los Angeles, and includes a number of NPR regulars and contributors from the online publication Slate. Day to Day also features the helpful daily reports from the Minnesota Public Radio show, Marketplace, which is "an informative conversation about business and economic news". Other regular features on Day to Day include commentaries on recent music releases from independent music critic Christian Bordal and curious and novel exposes and reports on the "odd underbelly" of the City of Angels, direct from Southern California.

  7. Day-to-day migrating and nonmigrating tidal variability due to the six-day planetary wave

    NASA Astrophysics Data System (ADS)

    Pedatella, N. M.; Liu, H.-L.; Hagan, M. E.

    2012-06-01

    To investigate day-to-day variability in the mesosphere and lower thermosphere (MLT), an idealized simulation of a six-day westward propagating zonal wave number-1 planetary wave is performed using the National Center for Atmospheric Research (NCAR) Thermosphere-Ionosphere-Mesosphere-Electrodynamics General Circulation Model (TIME-GCM). The six-day planetary wave introduces a six-day periodicity in the zonal mean atmosphere, migrating and nonmigrating tides, as well as in secondary waves that are produced by nonlinear planetary wave-tide interactions. We have further used the linear Global Scale Wave Model (GSWM) to isolate the effect of how the day-to-day changes in zonal mean zonal winds may influence tides in the MLT. The most significant changes are observed in the migrating diurnal tide (DW1), eastward propagating nonmigrating tides with zonal wave numbers-2 and -3 (DE2 and DE3), and a 20 hr eastward propagating wave with zonal wave number-2 (20E2). Because we have included the lower atmospheric source of nonmigrating tides, DE2 and DE3 are present with relatively large amplitudes in the MLT, even in the absence of planetary wave forcing. The 20E2 wave is produced by the nonlinear interaction between the DE3 and the six-day planetary wave, and its large amplitude indicates the importance of including the realistic spectra of nonmigrating tides in numerical simulations of planetary waves. The GSWM simulations reveal that the DW1 is not significantly influenced by the changes in the zonal mean winds. We thus conclude that the DW1 changes are driven by a combination of changes due to nonlinear interaction with the six-day planetary wave as well as changes due to zonal asymmetries that result from the six-day planetary wave. The six-day planetary wave induced changes in zonal mean zonal winds lead to a general reduction in the amplitude of DE2 and DE3, and introduce a slight periodic behavior in these tides. The effect of changing zonal mean zonal winds appears to be the primary driver of the changes in the DE2. However, for DE3, although the changes that can be attributed to zonal mean zonal wind variability are not insignificant, the primary driver of the DE3 perturbations appears to be the nonlinear interaction with the six-day planetary wave. Last, we demonstrate that the day-to-day changes in the DE3 introduce similar day-to-day changes in the daytime wave number-4 longitude structure in the low-latitude ionosphere. These results indicate that short-term variability in the low-latitude ionosphere is likely to be driven by similar short-term variability in nonmigrating tides in the MLT.

  8. Assessing Day-to Day Variability in the Vertical Distribution of Methane, Carbon Dioxide, and Ozone over Railroad Valley, NV

    NASA Astrophysics Data System (ADS)

    Iraci, L. T.; Johnson, M. S.; Yates, E. L.; Tanaka, T.; Sweeney, C.; Tadic, J.; Roby, M.; Andrews, A. E.; Lopez, J. P.

    2013-12-01

    In-situ observations of three trace gases over a remote desert site allow for an analysis of the variability of ozone (O3), methane (CH4), and carbon dioxide (CO2) in the free troposphere. Observations from June 2013 show almost no change from one day to the next in the boundary layer (BL) up to > 4 km (30% of the atmospheric column), while mixing ratios of methane and carbon dioxide show strong variability above this altitude. Ozone values also demonstrate variability above the boundary layer, and ozone day-to-day variability in the well-mixed BL is greater than that of CO2 or CH4. Results from week-long intensives in both June 2012 and June 2013, as well as monthly measurements over the period 2012-2013, will be compared to long-term vertical profile data sets at other locations (Trinidad Head, CA; Briggsdale, CO; and the Southern Great Plains site, OK). Variability above and in the boundary layer will be reported. To assess possible sources of variability, in situ data will be analyzed with a chemical trajectory model (GEOS-Chem v9-01-03). The North America nested-grid version of GEOS-Chem utilizes varying emission inventories and model parameterizations to simulate the emissions of greenhouse gases (CO2 and CH4, in this case) and ozone precursor gases. Tagged tracer simulations in GEOS-Chem allow for the geographical source apportionment of ozone, indicating whether the observed O3 was formed in the upper troposphere, middle troposphere, stratosphere, or any user-defined boundary layer location. For this study we will focus on ozone formed in the boundary layer over Asia, the Pacific Ocean, Mexico, Canada, and the United States. The importance of daily variability in the free tropospheric values of CO2, CH4, and O3 will be discussed in the context of column measurements collected from the surface or from space. Many data assimilation systems are designed to assume that changes to the total column average should be attributed primarily to changes within the boundary layer where large diurnal and seasonal cycles are presumed to dominate, but our data show that under some circumstances, this is not a valid presumption and can lead to a misinterpretation of the column measurement.

  9. Spatial versus day-to-day within-lake variability in tropical floodplain lake CH4 emissions--developing optimized approaches to representative flux measurements.

    PubMed

    Peixoto, Roberta B; Machado-Silva, Fausto; Marotta, Humberto; Enrich-Prast, Alex; Bastviken, David

    2015-01-01

    Inland waters (lakes, rivers and reservoirs) are now understood to contribute large amounts of methane (CH4) to the atmosphere. However, fluxes are poorly constrained and there is a need for improved knowledge on spatiotemporal variability and on ways of optimizing sampling efforts to yield representative emission estimates for different types of aquatic ecosystems. Low-latitude floodplain lakes and wetlands are among the most high-emitting environments, and here we provide a detailed investigation of spatial and day-to-day variability in a shallow floodplain lake in the Pantanal in Brazil over a five-day period. CH4 flux was dominated by frequent and ubiquitous ebullition. A strong but predictable spatial variability (decreasing flux with increasing distance to the shore or to littoral vegetation) was found, and this pattern can be addressed by sampling along transects from the shore to the center. Although no distinct day-to-day variability were found, a significant increase in flux was identified from measurement day 1 to measurement day 5, which was likely attributable to a simultaneous increase in temperature. Our study demonstrates that representative emission assessments requires consideration of spatial variability, but also that spatial variability patterns are predictable for lakes of this type and may therefore be addressed through limited sampling efforts if designed properly (e.g., fewer chambers may be used if organized along transects). Such optimized assessments of spatial variability are beneficial by allowing more of the available sampling resources to focus on assessing temporal variability, thereby improving overall flux assessments. PMID:25860229

  10. Day to day with COPD

    MedlinePLUS

    ... but there are things you can do every day to keep COPD from getting worse, to protect ... COPD - day to day; Chronic obstructive airways disease - day to day; Chronic obstructive lung disease - day to day ; Chronic ...

  11. On Day-to-Day Variability of Global Lightning Activity as Quantified from Background Schumann Resonance Observations

    NASA Astrophysics Data System (ADS)

    Mushtak, V. C.; Williams, E. R.

    2011-12-01

    Among the palette of methods (satellite, VLF, ELF) for monitoring global lightning activity, observations of the background Schumann resonances (SR) provide a unique prospect for estimating the integrated activity of global lightning activity in absolute units (coul2 km2/sec). This prospect is ensured by the SR waves' low attenuation, with wavelengths commensurate with the dimensions of dominant regional lightning "chimneys", and by the accumulating methodology for background SR techniques. Another benefit is the reduction of SR measurements into a compact set of resonance characteristics (modal frequencies, intensities, and quality factors). Suggested and tested in numerical simulations by T.R. Madden in the 1960s, the idea to invert the SR characteristics for the global lightning source has been farther developed, statistically substantiated, and practically realized here on the basis of the computing power and the quantity of experimental material way beyond what the SR pioneers had at their disposal. The critical issue of the quality of the input SR parameters is addressed by implementing a statistically substantiated sanitizing procedure to dispose of the fragments of the observed time series containing unrepresentative elements - local interference of various origin and strong ELF transients originating outside the major "chimneys" represented in the source model. As a result of preliminary research, a universal empirical sanitizing criterion has been established. Due to the fact that the actual observations have been collected from a set of individually organized ELF stations with various equipment sets and calibration techniques, the relative parameters in both input (the intensities) and output (the "chimney" activities) are being used as far as possible in the inversion process to avoid instabilities caused by calibration inconsistencies. The absolute regional activities - and so the sought for global activity in absolute units - is determined in the final stage from the estimated positions and relative activities of the modeled "chimneys" using SR power spectra at the stations with the most reliable calibrations. Additional stabilization in the procedure has been achieved by exploiting the Le Come/Goltzman inversion algorithm that uses the empirically estimated statistical characteristics of the input parameters. When applied to electric and/or magnetic observations collected simultaneously in January 2009 from six ELF stations in Poland (Belsk), Japan (Moshiri), Hungary (Nagycenk), USA (Rhode Island), India (Shillong), and Antarctica (Syowa), the inversion procedure reveals a general repeatability of diurnal lightning scenarios with variations of "chimney" centroid locations by a few megameters, while the estimated regional activity has been found to vary from day to day by up to several tens of percent. A combined empirical-theoretical analysis of the collected data aimed at selecting the most reliably calibrated ELF stations is presently in progress. All the effort is being made to transform the relative lightning activity into absolute units by the time of this meeting. The authors are greatly thankful to all the experimentalists who generously provided their observations and related information for this study.

  12. Day-to-day variability of equatorial and low latitude F-region ionosphere in the Indian zone

    Microsoft Academic Search

    R. S. Dabas; Neerja Sharma; M. G. K. Pillai; A. K. Gwal

    2006-01-01

    The F-region variability of the ionosphere during high solar activity periods have been studied using different hourly foF2 data from Indian stations, Thiruvananthapuram (8.5°N, 76.8°E), Kodaikanal (10.2°N, 77.5°E) near the Dip equator and Delhi (28.6°N, 77.2°E) located north of the equatorial ionization anomaly (EIA). During the study three types of changes have been observed, viz., single day abnormality, alternate day

  13. Day-to-day variability in the occurrence characteristics of Sq focus during d-months and its association with diurnal changes in the Declination component

    NASA Astrophysics Data System (ADS)

    Alex, S.; Jadhav, M. M.

    2007-11-01

    Scrutiny of the geomagnetic observations of the Declination component 'D' from equatorial and low-latitude locations in the Indian longitude revealed anomalous variations during d-months. Examination of the Quiet day (Ap?7) variations in the Declination component (Y in nT = H sin D) and Horizontal component (H) during the d-months (November, December, January, February) of the low solar activity year 1977 revealed the salient features associated with the day-to-day changes observed in Sq current system over the latitude chain in the Indo-Russian longitude. Diurnal variations in the east-west component Y and north-south component H were used to depict the effect of changes in the Sq current pattern for a selected set of Quiet days, which are classified into normal and abnormal days based on the trend in the variation of the Declination component. Normal days designated in the study clearly showed the expected pattern of variation in ? Y (eastward-directed field) in the morning hours and westward-directed field in the afternoon hours, and diurnal variation of ? H simultaneously showed the presence of northern Sq focus within the low-latitude range. In contrast, the abnormal days projected by the variation in ? Y and ? H on certain days of d-months showed an almost complete absence of the focus formation within the expected latitude extent. Day-to-day variability characteristics of the Declination component discussed in the study are illustrated in relation to modifications in the expected Sq current system by the invasion of the prevalent southern hemisphere current whorl to the northern hemisphere during the winter months. Some of the anomalous changes observed in the day-to-day variation in the latitudinal pattern of ? Y and ? H components are also interpreted as suggesting an influence of high-latitude magnetospheric current systems on certain quiet days.

  14. Ground-based observatory network, located in the Brazilian sector, to study the day-to-day variability of the ionosphere-thermosphere during the solar cycle 24

    NASA Astrophysics Data System (ADS)

    Fagundes, P. R.

    2013-12-01

    A new set of instrumentation (all-sky imaging, Fabry-Perot, and magnetometers) is being installed in the Universidade do Vale do Paraiba (UNIVAP) observatory network, which is located from near equatorial region to low-latitudes at Manaus(2.9oS,60.0oW, Dip-latitude 6.4oN), Palmas (10.2oS, 48.2oW,Dip-latitude 05.5oS), Itajaí (18.0oS, 51.7oW, Dip-latitude 12.1oS), and São José dos Campos (23.2oS, 45.9oW,Dip-latitude 17.6oS). These observatories have operated ionosondes since 2002, and this new instrumentation will provide observation to study the ionosphere and thermosphere day-to-day variability. The main topics that may be studied in detail are: a) Thermosphere-ionosphere response to geomagnetic disturbed periods; b) Propagations of gravity waves and planetary waves at thermosphere and their effects on ionosphere; c) Generation, evolution, and propagation of equatorial large scale and bottom side ionospheric irregularities; d) Ionospheric F3 layer studies at equatorial and low-latitude regions. In addition, the combination of ground-based and satellite data is important to improve the knowledge of ionosphere-thermosphere day-to-day variability. The new instrumentation has been funded by the Sao Paulo Research Foundation (FAPESP), Grant 2012/08445-9. Figure 1- A map of Brazil showing the locations of the UNIVAP observatories. Table1- Detail of the UNIVAP Observatory network.

  15. An Idiographic Examination of Day-to-Day Patterns of Substance Use Craving, Negative Affect, and Tobacco Use among Young Adults in Recovery

    ERIC Educational Resources Information Center

    Zheng, Yao; Wiebe, Richard P.; Cleveland, H. Harrington; Molenaar, Peter C. M.; Harris, Kitty S.

    2013-01-01

    Psychological constructs, such as negative affect and substance use cravings that closely predict relapse, show substantial intraindividual day-to-day variability. This intraindividual variability of relevant psychological states combined with the "one day at a time" nature of sustained abstinence warrant a day-to-day investigation of substance…

  16. The day-to-day occurrence of equatorial plasma bubbles measured from Vanimo, Papua New Guinea

    NASA Astrophysics Data System (ADS)

    Carter, B. A.; Yizengaw, E.; Francis, M.; Terkildsen, M. B.; Marshall, R. A.; Norman, R.; Zhang, K.

    2013-12-01

    An analysis of the occurrence of Equatorial Plasma Bubbles (EPBs) detected using a ground-based Global Positioning System (GPS) receiver located at Vanimo in South-east Asia will be presented. The 3-year (2000-2002) dataset employed shows that the EPB occurrence maximizes (minimizes) during the equinoxes (solstices), in good agreement with previous findings. The low-latitude ionosonde station at Vanimo is used in conjunction with the GPS receiver in an analysis of the day-to-day EPB occurrence variability during the equinox period. A superposed epoch analysis of the ionosonde data reveals that the height, and the change in height, of the F layer is 1 standard deviation (1?) larger on the days for which EPBs were detected, compared to non-EPB days. These results are interpreted using the generalized Rayleigh-Taylor (R-T) plasma instability growth rate, for which stronger upward drift of the lower-altitude F-layer plasma promotes faster growth of EPBs after sunset. These results are then compared to the results of the Thermosphere Ionosphere Electrodynamic General Circulation Model (TIEGCM), which surprisingly show strong similarities to the observations, despite only using geomagnetic and solar activity inputs. The TIEGCM is also used to directly calculate the hourly flux-tube integrated R-T growth rate. A superposed epoch analysis reveals that the modeled R-T growth rate is a little less than 1? higher on average for EPB days compared to non-EPB days. The implication of this result is that the TIEGCM generates almost enough day-to-day variability in order to account for the day-to-day EPB occurrence observed during the equinox. This result isn't necessarily expected due to the model's limited altitude coverage of 100-700 km (depending on solar activity) and the lack of ionospheric observation inputs. It is thought that the remaining variability could originate from either lower altitudes (e.g. atmospheric gravity waves from the troposphere) or from higher altitudes (resulting from coupling with the magnetosphere and solar wind), or potentially both. It is concluded that the continuing advancement of numerical modeling of the thermosphere and ionosphere, coupled with altitudes above and below, is required to better understand the day-to-day EPB occurrence.

  17. The Role of Books, Television, Computers and Video Games in Children's Day to Day Lives.

    ERIC Educational Resources Information Center

    Welch, Alicia J.

    A study assessed the role of various mass media in the day-to-day lives of school-aged children. Research questions dealt with the nature of children's media experiences at home, how use of media impacts school activities, the social context of media use, interior responses to different media, and whether gender or socioeconomic differences among…

  18. The Constant Cycle: Day to Day Critical Action of the QUIPPED Project

    ERIC Educational Resources Information Center

    Medves, Jennifer M.; Paterson, Margo; Schroder, Cori; Verma, Sarita; Broers, Teresa; Chapman, Christine; O'Riordan, Anne

    2008-01-01

    Action research in the critical paradigm involves a process of continual refection in and on action including the research process itself. In the second in a series of several papers we report on the day-to-day management of the QUIPPED project. The aim was to facilitate patient centred care through inter-professional collaboration with health…

  19. Perception updating and day-to-day travel choice dynamics in trac networks with information provision

    E-print Network

    Peeta, Srinivas

    Perception updating and day-to-day travel choice dynamics in trac networks with information is developed to capture the mechanism by which travelers update their travel time perceptions from one day, then selects an alternative based on the utility maximization princi- ple. The perception updating model

  20. The day-to-day monitoring of the 2011 severe drought in China

    NASA Astrophysics Data System (ADS)

    Lu, Er; Cai, Wenyue; Jiang, Zhihong; Zhang, Qiang; Zhang, Cunjie; Higgins, R. Wayne; Halpert, Michael S.

    2014-07-01

    Dry/wet condition has a large interannual variability. Decision-makers need to know the onset, duration, and intensity of drought, and require droughts be monitored at a daily to weekly scale. However, previous tools cannot monitor drought well at this short timescale. The Palmer Drought Severity Index has been found dissatisfactory in monitoring because of its complexity and numerous limitations. The Standardized Precipitation Index (SPI) always asks for a timescale, and precipitation is averaged over the period of the scale. Because of this, the SPI cannot be used for short scales, e.g., several days, and what it tells is the overall drought situation of the period. The weighted average of precipitation (WAP) developed by Lu (Geophys Res Lett 36:L12707, 2009) overcomes the deficiency of the SPI; it does not require a timescale, and can provide the drought (and flood) extent of each day. Therefore, the WAP can monitor drought at scales from daily to weekly, monthly, and any longer scale, and is really "flexible and versatile for all timescales". In this study, the standardized WAP (SWAP) is used to monitor the 2011 drought over China. Drought swept the country during the year from north to south and from east to west. In spring, a once-in-a-fifty-year drought occurred over the Yangtze River basin and the southern region, causing serious shortage of drinking water for people and livestock, as well as tremendous losses in agriculture and the shipping industry. Results show that the SWAP, with its monthly mean plots, can well reproduce the seasonal shift of the 2011 drought across the country. The animation of daily plots demonstrates that the SWAP would have been able to monitor the day-to-day variation of the spring drought around the Yangtze River basin. It can provide the details of the drought, such as when the drought emerged over the region, how long it maintained there (though drought area may move back and forth with extension and contraction of the area), and when the drought relieved over the basin.

  1. Day-to-Day Variability in Empathy as a Function of Daily Events and Mood

    Microsoft Academic Search

    John B. Nezlek; Gregory J. Feist; F. Carol Wilson; Rebecca M. Plesko

    2001-01-01

    Despite broad agreement that understanding a personality construct requires integrating trait and state levels of analysis, few studies have explicitly attempted such an integration. The present study did this by examining the relationships between trait and state measures of empathy. State measures were taken daily, with a focus on the day level (within-person) covariation between empathy and daily mood and

  2. Tektite 2 habitability research program: Day-to-day life in the habitat

    NASA Technical Reports Server (NTRS)

    Nowlis, D. P.

    1972-01-01

    Because it is widely agreed that the field of environmental psychology is quite young, it was determined that a sample of recorded observations from a representative mission should be included in the report on Tektite to give the professional reader a better feeling of normal day-to-day life in the isolated habitat. Names of the crew members have been replaced with numbers and some off-color words have been replaced by more acceptable slang; some remarks have been omitted that might lead to easy identification of the subjects. Otherwise, the following pages are exactly as transcribed during the late afternoons and the evenings of the mission.

  3. Day-to-day repeatability of the Pulse Time Index of Norm

    PubMed Central

    Posokhov, Igor N; Konradi, Aleksandra O; Shlyakhto, Eugeny V; Mamontov, Oleg V; Orlov, Artemy V; Rogoza, Anatoly N

    2014-01-01

    The pulse wave velocity (PWV) threshold for hypertensive target organ damage is presently set at 10 meters per second. New 24-hour monitors (eg, BPLab® and Vasotens®) provide several PWV measurements over a period of 24–72 hours. A new parameter, ie, the Pulse Time Index of Norm (PTIN), can be calculated from these data. The PTIN is defined as the percentage of a 24-hour period during which the PWV does not exceed 10 meters per second. The aim of the present study was to test the new PTIN for clinical feasibility using day-to-day repeatability analysis. Oscillometrically generated waveform files (n=85), which were previously used for research studies, were reanalyzed using the new 2013 version software of the Vasotens technology program, which enables calculation of PTIN. The intraclass correlation coefficient was 0.98 and Cronbach’s alpha was 0.97, indicating that the PTIN has excellent day-to-day repeatability and internal consistency. The present results show adequate repeatability, and PTIN assessment using the Vasotens technology appears to be feasible. PMID:24600253

  4. Revealing important nocturnal and day-to-day variations in fire smoke emissions through a multiplatform inversion

    NASA Astrophysics Data System (ADS)

    Saide, Pablo E.; Peterson, David A.; Silva, Arlindo; Anderson, Bruce; Ziemba, Luke D.; Diskin, Glenn; Sachse, Glen; Hair, Johnathan; Butler, Carolyn; Fenn, Marta; Jimenez, Jose L.; Campuzano-Jost, Pedro; Perring, Anne E.; Schwarz, Joshua P.; Markovic, Milos Z.; Russell, Phil; Redemann, Jens; Shinozuka, Yohei; Streets, David G.; Yan, Fang; Dibb, Jack; Yokelson, Robert; Toon, O. Brian; Hyer, Edward; Carmichael, Gregory R.

    2015-05-01

    We couple airborne, ground-based, and satellite observations; conduct regional simulations; and develop and apply an inversion technique to constrain hourly smoke emissions from the Rim Fire, the third largest observed in California, USA. Emissions constrained with multiplatform data show notable nocturnal enhancements (sometimes over a factor of 20), correlate better with daily burned area data, and are a factor of 2-4 higher than a priori estimates, highlighting the need for improved characterization of diurnal profiles and day-to-day variability when modeling extreme fires. Constraining only with satellite data results in smaller enhancements mainly due to missing retrievals near the emissions source, suggesting that top-down emission estimates for these events could be underestimated and a multiplatform approach is required to resolve them. Predictions driven by emissions constrained with multiplatform data present significant variations in downwind air quality and in aerosol feedback on meteorology, emphasizing the need for improved emissions estimates during exceptional events.

  5. An Idiographic Examination of Day-to-Day Patterns of Substance Use Craving, Negative Affect and Tobacco Use among Young Adults in Recovery

    PubMed Central

    Zheng, Yao; Wiebe, Richard P.; Cleveland, H. Harrington; Molenaar, Peter C. M.; Harris, Kitty S.

    2014-01-01

    Psychological constructs, such as negative affect and substance use cravings that closely predict relapse, show substantial intra-individual day-to-day variability. This intra-individual variability of relevant psychological states combined with the “one day of a time” nature of sustained abstinence warrant a day-to-day investigation of substance use recovery. This study examines day-to-day associations among substance use cravings, negative affect, and tobacco use among 30 college students in 12-step recovery from drug and alcohol addictions. To account for individual variability in day-to-day process, it applies an idiographic approach. The sample of 20 males and 10 females (mean age = 21) was drawn from members of a collegiate recovery community at a large university. Data were collected with end-of-day data collections taking place over an average of 26.7 days. First-order vector autoregression models were fit to each individual predicting daily levels of substance use cravings, negative affect, and tobacco use from the same three variables one day prior. Individual model results demonstrated substantial inter-individual differences in intra-individual recovery process. Based on estimates from individual models, cluster analyses were used to group individuals into two homogeneous subgroups. Group comparisons demonstrate distinct patterns in the day-to-day associations among substance use cravings, negative affect, and tobacco use, suggesting the importance of idiographic approaches to recovery management and that the potential value of focusing on negative affect or tobacco use as prevention targets depends on idiosyncratic processes. PMID:25309000

  6. Day-to-day compliance with Resource Conservation Recovery Act (RCRA)

    SciTech Connect

    Harris, W.E.; Hart, J.T. [Atlanta Environmental Management, Inc., GA (United States)

    1995-12-31

    Day-to-day compliance with requirements of the Resource Conservation Recovery Act (RCRA) is an important, yet difficult, component of environmental compliance. Non-compliance with RCRA can result in substantial financial penalties and/or major costs associated with clean-up of contaminated facilities. This session will include a review of all of the major RCRA, hazardous waste generator requirements and selected TSD requirements. Emphasis will be placed on requirements which regulated industries routinely fail and on which penalties for non- compliance may be levied. Specific procedures and suggestions for assuring continued compliance will be presented. Also included is a review of the RCRA waste characterization requirements and means for assuring compliance. Finally, examples of specific RCRA enforcement actions will be presented along with an explanation of how RCRA penalties are calculated and how RCRA penalties can be mitigated.

  7. Destigmatizing day-to-day practices: what developed countries can learn from developing countries

    PubMed Central

    ROSEN, ALAN

    2006-01-01

    The nature of and threshold for stigma associated with mental disorders appears to be different between developed and developing countries. Decreasing stigma can be achieved through a combination of the best Western educational and media strategies and the systematization of some important lessons from developing countries. At the macro-level, this involves: societal changes leading to being more inclusive and re-integrating people with mental illness into our communities; finding socially useful and culturally valued work roles for such marginalized people; re-extending our kinship networks, and re-valuing contact with people with mental illness and learning from their experiences. At the micro-level, this involves developing more destigmatizing day-to-day clinical practices, including: more holistic appraisal of disorder, abilities and needs; therapeutic optimism; a strengths orientation; engaging family and redeveloping an extended support network; celebration of age appropriate rites of passage; invoking the language of recovery; valuing veterans of mental illness as "spirit guides"; promoting consumers' community living as full citizens; engaging and involving the local community in taking responsibility for their own mental health. PMID:16757986

  8. Assessment of Day-to-Day Functioning in Prodromal and Early Huntington Disease

    PubMed Central

    Vaccarino, Anthony L; Sills, Terrence; Anderson, Karen E.; Endicott, Jean; Giuliano, Joseph; Guttman, Mark; Ho, Aileen K; Kupchak, Peter; Paulsen, Jane S.; Warner, John H.; Williams, Janet; Evans, Ken

    2011-01-01

    The Functional Rating Scale Taskforce for pre-Huntington Disease (FuRST-pHD) is a multinational, multidisciplinary initiative with the goal of developing a data-driven, comprehensive, psychometrically sound, rating scale for assessing symptoms and functional ability in prodromal and early Huntington disease (HD) gene expansion carriers. The process involves input from numerous sources to identify relevant symptom domains, including HD individuals, caregivers, and experts from a variety of fields, as well as knowledge gained from the analysis of data from ongoing large-scale studies in HD using existing clinical scales. This is an iterative process in which an ongoing series of field tests in prodromal (prHD) and early HD individuals provides the team with data on which to make decisions regarding which questions should undergo further development or testing and which should be excluded. We report here the development and assessment of the first iteration of interview questions aimed to assess functional impact in day-to-day activities in prHD and early HD individuals. PMID:21927718

  9. Day to day treatment variations of accelerated partial breast brachytherapy using a multi-lumen balloon

    PubMed Central

    Mehta, Keyur J.; Hong, Linda; Yaparpalvi, Ravindra; Montgomery, Leslie L.; Bodner, William; Tomé, Wolfgang A.; Kalnicki, Shalom

    2014-01-01

    Purpose To evaluate the variations of multi-lumen balloon (MLB)-based brachytherapy from simulation day to treatment day and their dosimetric impacts during accelerated partial breast irradiation (APBI). Material and methods A total of 42 CT images scanned from seven patients were evaluated with regards to daily variation due to of: 1) internal uncertainty: size and shape of balloon, seroma volume; 2) geometrical uncertainty-random: length of each catheter was measured for each fraction (total 70); 3) geometrical uncertainty-systematic: virtual systematic errors were tested by offsetting dwell positions. The original plans (as group A) had a mean value of 96.8% on V95 of the PTV_Eval. Plans were rerun (as group B) such that the mean value of the V95 was relaxed to 90.4%. By applying the reference plan to each daily CT image, variations of target coverage under different sources of error were evaluated. Results Shape and size of the balloon had means of < 1 mm decreased in diameter and < 0.4 cm3 decreased in volume; the mean seroma volume increased by 0.2 cm3. This internal variation has a mean of < 1% difference for both V90 and V95. The geometrical uncertainty made a mean deviation of 2.7 mm per root of sum of square. It caused the degradations of V90 and V95 by mean values of 1.0% and 1.2%, respectively. A systematic error of 3 mm and 4 mm would degrade both of V90 and V95 by 4% and 6%, respectively. The degradations on target coverage of the plans in group A were statistically the same as those in group B. Conclusions Overall, APBI treatments with MLB based brachytherapy are precise from day to day. However, minor variation due to daily treatment uncertainties can still degrade tumor bed coverage to an unacceptable coverage when V95 of the original plan is close to 90%. PMID:24790624

  10. Self Reports of Day-to-Day Function in a Small Cohort of People with Prodromal and Early HD

    PubMed Central

    Williams, Janet; Downing, Nancy; Vaccarino, Anthony L; Guttman, Mark; Paulsen, Jane S.

    2011-01-01

    Day-to-day functioning is a component of health-related quality of life and is an important end point for therapies to treat Huntington Disease (HD). Specific areas of day-to-day function changes have not been reported for prodromal or very early stages of HD. An exploratory self-report telephone interview was conducted with sixteen people with prodromal HD or early HD who met criteria designed to capture research participants most near to motor diagnosis. All completed semi-structured interviews on function in nine aspects of day-to-day life. Out of 16, 14 reported changes in at least one area. All day-to-day function areas were endorsed by at least one participant with driving being the most common area endorsed by 11/16. Changes in ability to perform some day-to-day tasks are experienced by people who are close to the time of clinical diagnosis for HD. Functional ability is likely to be an important component of outcome assessments of clinical trials and in ongoing clinical management. PMID:21901173

  11. Mindfulness as a moderator of the effect of implicit motivational self-concept on day-to-day behavioral motivation

    Microsoft Academic Search

    Chantal Levesque; Kirk Warren Brown

    2007-01-01

    Drawing from theories regarding the role of awareness in behavioral self-regulation, this research was designed to examine\\u000a the role of mindfulness as a moderator between implicit motivation and the motivation for day-to-day behavior. We hypothesized\\u000a that dispositional mindfulness (Brown and Ryan, J Pers Soc Psychol, 84, 822–848, 2003) would act to modify the expression of implicit autonomy orientation in daily

  12. Effects of light on NO3 uptake in small forested streams: diurnal and day-to-day variations

    SciTech Connect

    Mulholland, Patrick J [ORNL

    2006-08-01

    We investigated the effects of autotrophy on short-term variations in nutrient dynamics by measuring diurnal and day-to-day variations in light level, primary productivity, and NO{sub 3}{sup -} uptake during early and late spring in 2 forested streams, the East and West Forks of Walker Branch in eastern Tennessee, USA. We predicted that diurnal and day-to-day variations in NO{sub 3}{sup -} uptake rate would be larger in the West Fork than in the East Fork in early spring because of higher rates of primary productivity resulting from a more stable substratum in the West Fork. We also predicted minimal diurnal variations in both streams in late spring after forest leaf emergence when light levels and primary productivity are uniformly low. Reach-scale rates of gross primary production (GPP) were determined using the diurnal dissolved O{sub 2} change technique, and reach-scale rates of NO{sub 3}{sup -} uptake were determined by tracer {sup 15}N-NO{sub 3}{sup -} additions. In the West Fork, significant diurnal and day-to-day variations in NO{sub 3}{sup -} uptake were related to variations in light level and primary productivity in early spring but not in late spring, consistent with our predictions. In early spring, West Fork NO{sub 3}{sup -} uptake rates were 2 to 3x higher at midday than during predawn hours and 50% higher on 2 clear days than on an overcast day several days earlier. In the East Fork, early spring rates of GPP were 4 to 5x lower than in the West Fork and diurnal and day-to-day variations in NO{sub 3}{sup -} uptake rates were <30%, considerably lower than in the West Fork. However, diurnal variations in NO{sub 3}{sup -} uptake rates were greater in late spring in the East Fork, possibly because of diurnal variation in water temperature. Our results indicate the important role of autotrophs in nutrient uptake in some forested streams, particularly during seasons when forest vegetation is dormant and light levels are relatively high. Our results also have important implications for longer-term assessments of N cycling in streams that rely on daytime measurements or measurements only under limited weather conditions (i.e., clear days).

  13. Seasonal and Day-to-day Variations of Thermospheric Tides and Dynamo Fields Studied with a Long-term Whole Atmosphere-Ionosphere Coupled Simulation

    NASA Astrophysics Data System (ADS)

    Jin, H.; Miyoshi, Y.; Fujiwara, H.; Shinagawa, H.

    2014-12-01

    Day-to-day and longer variations of ionospheric electron density, which affect various space weather applications, are caused originally from the solar activity variations and the rotation of the sun as well as the lower atmospheric activity. For the latter source, atmospheric waves such as tides and planetary waves are generated in the moist convection, which propagate through the middle atmosphere affected by various dynamical processes such as their interactions with the mean zonal wind and other waves, and reach the lower thermosphere where they induce dynamo electric fields. According to the recent satellite and ground-based observations, the characteristics of tides and planetary waves in the lower thermosphere are becoming known more clearly, such as the seasonal and latitude variations of major tides, planetary wave-like oscillations, and irregular variations during stratospheric sudden warming, and so on. In this paper, we use a whole atmosphere-ionosphere coupled model called GAIA, and have carried out a simulation from 1996 to 2013 with realistic forcing from the lower atmosphere by nudging the meteorological reanalysis (JRA) into the model. By analyzing the long-term model data, we investigate how the tidal variability and planetary waves in the lower thermosphere produce the seasonal and day-to-day variations in the dynamo electric field as well as the origin of the variations in the lower and middle atmospheres.

  14. How to reduce day-to-day variation of leaf area index derived from digital cover photography?

    NASA Astrophysics Data System (ADS)

    Hwang, Y. R.; Ryu, Y.; Kimm, H.; Macfarlane, C.; Lang, M.; Sonnentag, O.

    2014-12-01

    Leaf area index (LAI) is essential for computing canopy level carbon and water fluxes. Nowadays, it is possible to automatically monitor daily LAI using low-cost sensors, such as digital cameras and LED-sensors. Recent studies have shown that RAW camera format images can improve the estimation of gap fractions and LAI compared to JPEG format. However, whether RAW-based methods can effectively reduce day-to-day variation of LAI time series has not been investigated. In this study, we used two methods to compute gap fraction. The first method separates sky and vegetation pixels using a single threshold in the blue band histogram. The second method interpolates the background sky image from pure sky pixels, and computes the transmittance from original and reconstructed images. In order to investigate which method is more accurate in reducing day-to-day variation of LAI, we first conducted a controlled experiment with punched panels which included different hole size and gap fractions on the rooftop. Then, we applied both methods to photos collected daily over a year at deciduous forest and evergreen forest in South Korea.

  15. Imposing order: a process to manage day-to-day activities in two-earner families with preschool children.

    PubMed

    Hall, Wendy A

    2007-02-01

    This study investigated how English and Canadian families with preschool children used strategies to impose varying levels of order to manage day-to-day activities. This grounded theory study is a secondary analysis of 55 hours of participant observation and interviews with 58 individuals and 29 couples. Constant comparative analysis and theoretical sampling were used to construct categories. To attempt to impose order, strategies used by families included organizing and planning, establishing routines, setting limits, setting standards, purchasing services and technology, and delegating tasks. Most families used these strategies successfully; costs outweighed benefits where families concentrated inflexibly on a few strategies in particular spheres of activity or had difficulty using strategies. Families using a variety of strategies flexibly were better at balancing personal and family goals, promoting fulfillment, health, and happiness for each family member, and fostering family development and commitment. Imposing order links everyday family dynamics and concerns to long-term goals. PMID:17220382

  16. Individual differences in the day-to-day experience of chronic pain: a prospective daily study of rheumatoid arthritis patients.

    PubMed

    Affleck, G; Tennen, H; Urrows, S; Higgins, P

    1991-01-01

    Explored the distribution and temporal patterning of daily pain reported by 47 patients with rheumatoid arthritis (RA) for 75 consecutive days. Approximately half the pain series were significantly positively skewed, trended significantly across the recording period, or both. One fourth of the sample had relatively painful "outlier" days that clustered together. Most series displayed a significant autocorrelation in pain intensity across successive days even when the series were detrended. Patients with more active disease had pain that was more intense but more predictable from day to day and reported fewer painful outlying days and briefer episodes of atypically severe pain. Patients describing themselves as more depressed on the Center for Epidemiological Stress Depression Scale also reported more intense pain across the recording period, independent of their level of disease activity and disability. Implications for daily process studies of RA pain are discussed. PMID:1765037

  17. Better or Worse: a Study of Day-to-Day Changes over Five Months of Rosen Method Bodywork Treatment for Chronic Low Back Pain

    PubMed Central

    Fogel, Alan

    2013-01-01

    Background Fluctuations of good days and bad days—in physical symptoms and emotional states—are common for individuals with chronic illness. This pilot study examines these fluctuations during bodywork treatment. Purpose We analyzed changes in daily self-reports over a period of five months for five individuals who received weekly treatments of Rosen Method Bodywork (RMB), which uses touch and words to enhance body awareness of physical sensations and emotional states. Subjects and Design Five subjects (aged 31–56) who had chronic low back pain (CLBP) received 16 weekly treatments given by three experienced RMB practitioners. Measures Pre- and posttreatment assessments covered demographics, disability, and pain. Clients also completed daily bedtime assessments of pain, fatigue, emotional state, and sense of control during the entire treatment period. Results All clients reported reductions in pain and/or disability in post- compared to pretreatment. In spite of a high level of day-to-day variability in the daily assessments, there were significant reductions in pain and fatigue, and significant increases in positive emotional state and sense of control across the treatment period. In reaching this end, however, some clients had slow and steady improvements, some improved more rapidly, while others got worse before they got better. Conclusions The natural course of healing—with its inevitable fluctuations in symptoms—is part of a process leading to successful treatment outcomes. Rosen Method Bodywork may be especially helpful in developing and accepting both sensory and emotional body awareness changes that facilitate overall improvement. PMID:24000305

  18. Utilizing 3D-visualization to apply compulsory ALARA principles in nuclear power plant design and day-to-day operation

    SciTech Connect

    Sanders, R. L.; Lake, J. E. [Oak Ridge National Laboratory, Computational Sciences and Engineering Div., Mail Stop 6085, One Bethel Valley Road, Oak Ridge, TN 37831 (United States)

    2006-07-01

    The development of an advanced visualization and simulation tool to support both design as well as day-to-day operation is presented. This tool exploits cutting edge computer graphics, physics-based effects modeling, virtual reality, and gaming technologies to establish a system that can eventually be used for the administrative planning and training of plant operators and design engineers. (authors)

  19. Predicting Day-to-Day Changes in Students' School-Related Affect from Daily Academic Experiences and Social Interactions

    ERIC Educational Resources Information Center

    Altermatt, Ellen Rydell

    2015-01-01

    This study examined the role that everyday academic successes and failures--and the interactions with family members and peers that follow these events--play in predicting day-to-day changes in children's emotional responses to school. Middle school students (N = 101; mean age = 11.62 years) completed daily assessments of their academic…

  20. Temperature variability within Makassar Strait

    NASA Astrophysics Data System (ADS)

    Ffield, Amy; Vranes, Kevin; Gordon, Arnold L.; Dwi Susanto, R.; Garzoli, Silvia L.

    2000-01-01

    Recent mooring observations of ocean temperature provide the first high resolution, long term record of temperature variability in the Makassar Strait of the Indonesian Seas. The mooring observations span the entire cycle of the strong 1997/1998 El Niño. A high correlation (r = 0.67) is found between variability in the average thermocline temperature, to variability in the southward Makassar volume transport: during high (low) volume transport, the average temperature of the thermocline is also high (low). In addition, from nearly 15 years of XBT data, the Makassar thermocline temperature is shown to be highly correlated (r = 0.77) to SOI. This reveals that the Makassar temperature field-when coupled with the throughflow-transmits the equatorial Pacific El Niño and La Niña temperature fluctuations into the Indian Ocean. The ENSO variability in the internal energy transport is calculated: 0.63 PW during the La Niña months of December 1996 through February 1997, and 0.39 PW during the El Niño months of December 1997 through February 1998.

  1. Day-to-day fluctuation of point-of-care circulating cathodic antigen test scores and faecal egg counts in children infected with Schistosoma mansoni in Ethiopia

    PubMed Central

    2014-01-01

    Background Determining the variation of circulating cathodic antigen (CCA) in urine and egg counts variation in stool between days in Schistosoma mansoni (S. mansoni) infected individuals is vital to decide whether or not to rely on a single-sample test for diagnosis of Schistosomiasis. In this study, the magnitude of day-to-day variation in urine-CCA test scores and in faecal egg counts was evaluated in school children in Ethiopia. Methods A total of 620 school children (age 8 to 12 years) were examined for S. mansoni infection using double Kato-Katz and single urine-CCA cassette methods (batch 32727) on three consecutive days. Results The prevalence of S. mansoni infection was 81.1% based on triple urine-CCA-cassette test and 53.1% based on six Kato-Katz thick smears. Among the study participants, 26.3% showed fluctuation in urine CCA and 32.4% showed fluctuation in egg output. Mean egg count as well as number of cases in each class of intensity and intensity of cassette band color varied over the three days of examination. Over 85% of the children that showed day-to-day variations in status of S. mansoni infection from negative to positive or vice versa by the Kato-Katz and the CCA methods had light intensity of infection. The fluctuation in both the CCA test scores and faecal egg count was not associated with age and sex. Conclusions The current study showed day-to-day variation in CCA and Kato-Katz test results of children infected with S. mansoni. This indicates the necessity of more than one urine or stool samples to be collected on different days for more reliable diagnosis of S. mansoni infection in low endemic areas. PMID:24742192

  2. A comprehensive survey of atmospheric quasi 3 day planetary-scale waves and their impacts on the day-to-day variations of the equatorial ionosphere

    NASA Astrophysics Data System (ADS)

    Liu, Guiping; England, Scott L.; Immel, Thomas J.; Frey, Harald U.; Mannucci, Anthony J.; Mitchell, Nicholas J.

    2015-04-01

    This study reports a comprehensive survey of quasi 3 day (2.5-4.5 day period) planetary-scale waves in the low-latitude mesosphere and lower thermosphere using the temperature observations from Thermosphere Ionosphere and Mesosphere Electric Dynamics/Sounding of the Atmosphere using Broadband Emission Radiometry throughout 2002-2012. Occurrences and properties of the waves, including the eastward propagating zonal wave numbers of 1-3 (E1-E3) and vertical wavelengths, are determined for each case. The impacts of these waves on the equatorial ionosphere are investigated by searching for the corresponding variations with the same periods and wave numbers in total electron content (TEC) from the concurrent observations of the ground-based GPS network. For a threshold amplitude of 4 K in temperature, a total of 300 waves are identified, of which there are 186 E1, 63 E2, and 51 E3 events. The mean amplitudes and vertical wavelengths of these waves are calculated to be about 7.9 K and 34 km for the E1, 5.7 K and 29 km for the E2, and 5.1 K and 27 km for the E3, having the standard deviations of 1.5 K and 6.5 km, 0.6 K and 5.6 km, and 0.5 K and 6.7 km. Occurrences of the E1 cases are not observed to depend on season, but the large-amplitude (>8 K) cases occur more often during solstices than at equinoxes. Similarly, the E2 and E3 cases are observed to occur most often in January-February and May-August. Among these waves, 199 cases (66%) are found to have the corresponding variations in the equatorial ionosphere with amplitudes ?4.2% relative to the mean TEC values (corresponding to 90th percentile). Most of these waves have long vertical wavelengths and large amplitudes (˜3 times more than short vertical wavelength and small-amplitude waves). Because no seasonal or solar cycle dependence on the frequency at which these waves have corresponding variations in the ionosphere at this TEC perturbation threshold is observed, we conclude that there is no seasonal and solar cycle dependence on the propagation of such waves from the mesopause region to higher altitudes. We also identify that only 28 cases (19%) of the E1 TEC variations do not correspond to any E1 waves, which is consistent with the hypothesis that E1 waves are the primary cause of E1 TEC variations. Conditions that are favorable for 3 day waves to create ionospheric variations are present approximately two thirds of the time. This study quantifies the importance and frequency of atmospheric quasi 3 day planetary-scale waves on the day-to-day variations of the equatorial ionosphere using a statistical rather than case study approach.

  3. Conjugate Point Equatorial Experiment (COPEX) campaign in Brazil: Electrodynamics highlights on spread F development conditions and day-to-day variability

    Microsoft Academic Search

    M. A. Abdu; I. S. Batista; B. W. Reinisch; J. R. de Souza; J. H. A. Sobral; T. R. Pedersen; A. F. Medeiros; N. J. Schuch; E. R. de Paula; K. M. Groves

    2009-01-01

    A Conjugate Point Equatorial Experiment (COPEX) campaign was conducted during the October–December 2002 period in Brazil, with the objective to investigate the equatorial spread F\\/plasma bubble irregularity (ESF) development conditions in terms of the electrodynamical state of the ionosphere along the magnetic flux tubes in which they occur. A network of instruments, including Digisondes, optical imagers, and GPS receivers, was

  4. Day-to-day co-variations of psychological and physical symptoms of the menstrual cycle: insights to individual differences in steroid reactivity.

    PubMed

    Kiesner, Jeff; Pastore, Massimiliano

    2010-04-01

    The associations between physical and psychological symptoms of the menstrual cycle have not been carefully studied in past research, but may lead to a better understanding of the underlying mechanisms of these symptoms. The present study examines the day-to-day co-variations among physical and psychological symptoms of the menstrual cycle. These symptoms were evaluated on a daily basis across one entire menstrual cycle, with a non-clinical sample of 92 university students. Results showed that headaches, gastrointestinal problems, lower abdominal bloating, skin changes, and breast changes, were all significantly associated with higher levels of psychological symptoms; whereas back and joint pain, lower abdominal cramps, cervical mucous, and menstrual flow, were not associated with psychological symptoms. However, significant differences in these associations were observed across individuals for back and joint pain, headaches, lower abdominal cramps, skin changes, and menstrual flow: Whereas some women demonstrated higher levels of psychological symptoms associated with these physical symptoms, other women demonstrated lower levels of psychological symptoms. Finally, correlations among the associations between physical and psychological symptoms (slopes) demonstrated clear differences across the different physical symptoms. These results indicate that, although higher levels of some physical symptoms are associated with higher levels of psychological symptoms, there are significant differences in the magnitude and direction of these relations across individuals. Further consideration of physical symptoms may provide useful information for understanding individual differences in symptom profiles and response to steroid fluctuations, and for improving differential diagnosis and treatment planning and evaluation. PMID:19729249

  5. A validation of the application of D2O stable isotope tracer techniques for monitoring day-to-day changes in muscle protein subfraction synthesis in humans

    PubMed Central

    Wilkinson, Daniel J.; Franchi, Martino V.; Brook, Matthew S.; Narici, Marco V.; Williams, John P.; Mitchell, William K.; Szewczyk, Nathaniel J.; Greenhaff, Paul L.; Atherton, Philip J.

    2013-01-01

    Quantification of muscle protein synthesis (MPS) remains a cornerstone for understanding the control of muscle mass. Traditional [13C]amino acid tracer methodologies necessitate sustained bed rest and intravenous cannulation(s), restricting studies to ?12 h, and thus cannot holistically inform on diurnal MPS. This limits insight into the regulation of habitual muscle metabolism in health, aging, and disease while querying the utility of tracer techniques to predict the long-term efficacy of anabolic/anticatabolic interventions. We tested the efficacy of the D2O tracer for quantifying MPS over a period not feasible with 13C tracers and too short to quantify changes in mass. Eight men (22 ± 3.5 yr) undertook one-legged resistance exercise over an 8-day period (4 × 8–10 repetitions, 80% 1RM every 2nd day, to yield “nonexercised” vs. “exercise” leg comparisons), with vastus lateralis biopsies taken bilaterally at 0, 2, 4, and 8 days. After day 0 biopsies, participants consumed a D2O bolus (150 ml, 70 atom%); saliva was collected daily. Fractional synthetic rates (FSRs) of myofibrillar (MyoPS), sarcoplasmic (SPS), and collagen (CPS) protein fractions were measured by GC-pyrolysis-IRMS and TC/EA-IRMS. Body water initially enriched at 0.16–0.24 APE decayed at ?0.009%/day. In the nonexercised leg, MyoPS was 1.45 ± 0.10, 1.47 ± 0.06, and 1.35 ± 0.07%/day at 0–2, 0–4, and 0–8 days, respectively (?0.05–0.06%/h). MyoPS was greater in the exercised leg (0–2 days: 1.97 ± 0.13%/day; 0–4 days: 1.96 ± 0.15%/day, P < 0.01; 0–8 days: 1.79 ± 0.12%/day, P < 0.05). CPS was slower than MyoPS but followed a similar pattern, with the exercised leg tending to yield greater FSRs (0–2 days: 1.14 ± 0.13 vs. 1.45 ± 0.15%/day; 0–4 days: 1.13 ± 0.07%/day vs. 1.47 ± 0.18%/day; 0–8 days: 1.03 ± 0.09%/day vs. 1.40 ± 0.11%/day). SPS remained unchanged. Therefore, D2O has unrivaled utility to quantify day-to-day MPS in humans and inform on short-term changes in anabolism and presumably catabolism alike. PMID:24381002

  6. A Peltier-based variable temperature source

    NASA Astrophysics Data System (ADS)

    Molki, Arman; Roof Baba, Abdul

    2014-11-01

    In this paper we propose a simple and cost-effective variable temperature source based on the Peltier effect using a commercially purchased thermoelectric cooler. The proposed setup can be used to quickly establish relatively accurate dry temperature reference points, which are necessary for many temperature applications such as thermocouple calibration.

  7. Variable color temperature fluorescent lamp

    NASA Astrophysics Data System (ADS)

    Ravi, J.; Maya, J.

    2000-05-01

    Color temperature change in a mercury-rare gas low pressure discharge has been investigated. Different pulse waveforms have been employed to increase the ratio of mercury upper level transitions with respect to the resonant 254 nm radiation. Low pressure fluorescent light sources were made with coatings consisting of a blue phosphor, sensitive to 365 nm ultraviolet radiation, blended with the standard 254 nm excited red/green phosphors. With a fast rise excitation waveform, a color temperature rise of as much as 1700 K was realized although at a cost of 26% in relative luminous efficacy. An improved scheme for greater color temperature change is proposed based on a phosphor that is excitable by the mercury 185 nm ultraviolet radiation but which does not absorb 254 nm radiation.

  8. Variable color temperature fluorescent lamp

    Microsoft Academic Search

    J. Ravi; J. Maya

    2000-01-01

    Color temperature change in a mercury-rare gas low pressure discharge has been investigated. Different pulse waveforms have been employed to increase the ratio of mercury upper level transitions with respect to the resonant 254 nm radiation. Low pressure fluorescent light sources were made with coatings consisting of a blue phosphor, sensitive to 365 nm ultraviolet radiation, blended with the standard

  9. Superconductor having variable transition temperature

    Microsoft Academic Search

    G. A. Spiering; E. Revolinsky; D. J. Beerntsen

    1967-01-01

    A superconducting alloy having the general formula Nb(Se\\/sub 2-x\\/N\\/sub x\\/) where N is either sulfur or tellurium and x is a number less than 0.7. The element N, here being an anion, thus occupies selenium lattice sites. The transition temperature of the alloy is inversely proportional to the amount of sulfur or tellurium at a value between 2.0 and 7.0°K.

  10. Variable temperature semiconductor film deposition

    DOEpatents

    Li, X.; Sheldon, P.

    1998-01-27

    A method of depositing a semiconductor material on a substrate is disclosed. The method sequentially comprises (a) providing the semiconductor material in a depositable state such as a vapor for deposition on the substrate; (b) depositing the semiconductor material on the substrate while heating the substrate to a first temperature sufficient to cause the semiconductor material to form a first film layer having a first grain size; (c) continually depositing the semiconductor material on the substrate while cooling the substrate to a second temperature sufficient to cause the semiconductor material to form a second film layer deposited on the first film layer and having a second grain size smaller than the first grain size; and (d) raising the substrate temperature, while either continuing or not continuing to deposit semiconductor material to form a third film layer, to thereby anneal the film layers into a single layer having favorable efficiency characteristics in photovoltaic applications. A preferred semiconductor material is cadmium telluride deposited on a glass/tin oxide substrate already having thereon a film layer of cadmium sulfide.

  11. Variable temperature semiconductor film deposition

    DOEpatents

    Li, Xiaonan (Golden, CO); Sheldon, Peter (Lakewood, CO)

    1998-01-01

    A method of depositing a semiconductor material on a substrate. The method sequentially comprises (a) providing the semiconductor material in a depositable state such as a vapor for deposition on the substrate; (b) depositing the semiconductor material on the substrate while heating the substrate to a first temperature sufficient to cause the semiconductor material to form a first film layer having a first grain size; (c) continually depositing the semiconductor material on the substrate while cooling the substrate to a second temperature sufficient to cause the semiconductor material to form a second film layer deposited on the first film layer and having a second grain size smaller than the first grain size; and (d) raising the substrate temperature, while either continuing or not continuing to deposit semiconductor material to form a third film layer, to thereby anneal the film layers into a single layer having favorable efficiency characteristics in photovoltaic applications. A preferred semiconductor material is cadmium telluride deposited on a glass/tin oxide substrate already having thereon a film layer of cadmium sulfide.

  12. Understanding Surface Temperature Variability during the Pliocene

    NASA Astrophysics Data System (ADS)

    Haywood, Alan; Hunter, Stephen; Dowsett, Harry; Prescott, Caroline; Dolan, Aisling

    2015-04-01

    Surface temperatures during the Pliocene have often been characterised as being warm and relatively stable. The link between Milankovitch cycles, insolation and global ice volume (as demonstrated by the magnitude of negative and positive benthic oxygen isotope excursions), appears to have been weaker in the Pliocene compared to the Pleistocene. However, the marine benthic oxygen isotope record may over represent the signal of temperature change from the high latitudes. Away from ice sheet regions, where stronger ice sheet/sea-ice albedo feedbacks are expected in response to changes in insolation, the magnitude of surface temperature variability due to Milankovitch cycles would have been the same, or very similar, in the Pliocene (compared to the Quaternary). Pleistocene and Holocene surface temperatures have not been generalised in the same way as the Pliocene and studies concentrate on reconstructing, modelling and understanding discrete climate events, as well as critical climate transitions. It is appreciated that whilst an event, or events, may have a similar signature in terms of the magnitude of any benthic oxygen isotope (or ice core) excursion, they may still display unique surface temperature characteristics that distinguish one glacial or interglacial from another. This realisation has been possible due to the number of high resolution surface temperature records available. Compared to the Quaternary there are relatively few high-resolution surface temperature records to help constrain the nature of local to regional Pliocene surface temperature variability, although new records are emerging quickly. Regardless of this, our current understanding of Pliocene surface temperature variability at a regional as well as global scale is still emerging. Here we use Hadley Centre Coupled Climate Model version 3 (HadCM3) to explore the nature of Pliocene surface temperature variability and to explore the premise that individual benthic oxygen isotope events in the Pliocene will have unique characteristics of surface temperature change caused just by variations in insolation. Firstly, we focus our attention on intervals within the mid Pliocene Warm Period (3.3 to 3 million years ago) that are characterised by negative benthic isotope excursions, and therefore are presumed to represent relatively warm "interglacial-like" events (specifically Marine Isotope Stages K1, KM5c, G17 and KM3). Secondly, we also present results from the first fully transient simulation using a full complexity climate model (FAMOUS) for the interval between the "glacial" event M2 and "interglacial" event KM3. We demonstrate how comparing model simulations that capture the effects of orbital variability with newly generated high resolution proxy records of surface temperature change can alter our current understanding of where (geographically) models perform well or poorly compared to data. We conclude that even when considering orbital forcing alone, discrete climate events in the Pliocene were indeed characterised by unique regional signals of surface temperature change, and that broad generalisations concerning Pliocene surface temperature patterns are at best incomplete.

  13. Sea surface temperature variability: patterns and mechanisms.

    PubMed

    Deser, Clara; Alexander, Michael A; Xie, Shang-Ping; Phillips, Adam S

    2010-01-01

    Patterns of sea surface temperature (SST) variability on interannual and longer timescales result from a combination of atmospheric and oceanic processes. These SST anomaly patterns may be due to intrinsic modes of atmospheric circulation variability that imprint themselves upon the SST field mainly via surface energy fluxes. Examples include SST fluctuations in the Southern Ocean associated with the Southern Annular Mode, a tripolar pattern of SST anomalies in the North Atlantic associated with the North Atlantic Oscillation, and a pan-Pacific mode known as the Pacific Decadal Oscillation (with additional contributions from oceanic processes). They may also result from coupled ocean-atmosphere interactions, such as the El Niño-Southern Oscillation phenomenon in the tropical Indo-Pacific, the tropical Atlantic Niño, and the cross-equatorial meridional modes in the tropical Pacific and Atlantic. Finally, patterns of SST variability may arise from intrinsic oceanic modes, notably the Atlantic Multidecadal Oscillation. PMID:21141660

  14. Forecasting neutron star temperatures: predictability and variability

    E-print Network

    Dany Page; Sanjay Reddy

    2013-07-17

    It is now possible to model thermal relaxation of neutron stars after bouts of accretion during which the star is heated out of equilibrium by nuclear reactions in its crust. Major uncertainties in these models can be encapsulated in modest variations of a handful of fudge parameters that change the crustal thermal conductivity, specific heat, and heating rates. Observations of thermal relaxation constrain these fudge parameters and allow us to predict longer term variability in terms of the neutron star core temperature. We demonstrate this explicitly by modeling ongoing thermal relaxation in the neutron star XTE J1701-462. Its future cooling, over the next 5 to 30 years, is strongly constrained and depends mostly on its core temperature, uncertainties in crust physics having essentially been pinned down by fitting to the first three years of observations.

  15. Infrared Variability from Circumbinary Disc Temperature Modulations

    E-print Network

    Bodman, Eva

    2015-01-01

    The temperature of a circumbinary disc edge should undulate due to variations in illumination as a function of binary orbital phase. We explore circumbinary disc temperature variations as a source of broad-band infrared light curve variability. Approximating the wall of a circumbinary disc edge as a wide optically thick cylinder with surface temperature dependent on its illumination, we find that a binary comprised of 1 M$_\\odot$ and 0.5 M$_\\odot$ pre-main sequence stars in a $\\sim$15.5 day period, would exhibit the largest amplitude variations of $\\sim$9% at 3.77 and 4.68 {\\mu}m as seen by a distant observer. The amplitude of variations and shape of the light curve is sensitive to the luminosity and mass ratios of the stars in the binary, the radius of the circumbinary disc clearing, the binary separation, and the orbital inclination. The light curve variations are smooth and very red with a non-sinusoidal shape for most of the parameter space explored. Possible morphologies include a single peak with a flat...

  16. The Day-to-Day Acute Effect of Wake Therapy in Patients with Major Depression Using the HAM-D6 as Primary Outcome Measure: Results from a Randomised Controlled Trial

    PubMed Central

    Martiny, Klaus; Refsgaard, Else; Lund, Vibeke; Lunde, Marianne; Sørensen, Lene; Thougaard, Britta; Lindberg, Lone; Bech, Per

    2013-01-01

    Background This paper reports day-to-day data for from a one-week intervention phase, part of a 9-weeks randomised parallel study with patient having major depression (data from weekly visits have been reported). Wake therapy (sleep deprivation) has an established antidepressant effect with onset of action within hours. Deterioration on the following night’s sleep is, however, common, and we used daily light therapy and sleep time stabilisation as a preventive measure. In particular, we evaluated the day-to-day acute effect of and tolerance to sleep deprivation and examined predictors of response. Methods Patients were assessed at psychiatric inpatient wards. In the wake group (n?=?36), patients did three wake therapies in combination with light therapy each morning together with sleep time stabilisation. In the exercise group (n?=?38), patients did daily exercise. Hamilton subscale scores were primary outcome (not blinded), secondary outcome was self-assessment data from the Preskorn scale and sleep. Results Patients in the wake therapy group had an immediate, large, stable, and statistically significant better antidepressant effect than patients in the exercise group with response rates at day5 of 75.0%/25.1% and remission rates of 58.6%/6.0%, respectively. The response and remission rates were diminished at day8 with response rates of 41.9%/10.1% and remission rates of 19.4%/4.7%, respectively. Patients and ward personnel found the method applicable with few side effects. Positive diurnal variation (mood better in the evening) predicted a larger response to wake therapy. In the wake group napping on days after intervention predicted greater deterioration on day8. Conclusions The intervention induced an acute antidepressant response without relapse between wake nights but with a diminishing effect after intervention. Development is still needed to secure maintenance of response. Avoiding napping in the days after wake therapy is important. Trial Registration Clinical trials.gov NCT00149110 PMID:23840645

  17. Predation Life History Responses to Increased Temperature Variability

    PubMed Central

    Barbosa, Miguel; Pestana, Joao; Soares, Amadeu M. V. M.

    2014-01-01

    The evolution of life history traits is regulated by energy expenditure, which is, in turn, governed by temperature. The forecasted increase in temperature variability is expected to impose greater stress to organisms, in turn influencing the balance of energy expenditure and consequently life history responses. Here we examine how increased temperature variability affects life history responses to predation. Individuals reared under constant temperatures responded to different levels of predation risk as appropriate: namely, by producing greater number of neonates of smaller sizes and reducing the time to first brood. In contrast, we detected no response to predation regime when temperature was more variable. In addition, population growth rate was slowest among individuals reared under variable temperatures. Increased temperature variability also affected the development of inducible defenses. The combined effects of failing to respond to predation risk, slower growth rate and the miss-match development of morphological defenses supports suggestions that increased variability in temperature poses a greater risk for species adaptation than that posed by a mean shift in temperature. PMID:25250677

  18. Holocene subsurface temperature variability in the eastern Antarctic continental margin

    NASA Astrophysics Data System (ADS)

    Kim, Jung-Hyun; Crosta, Xavier; Willmott, Veronica; Renssen, Hans; Bonnin, Jérôme; Helmke, Peer; Schouten, Stefan; Sinninghe Damsté, Jaap S.

    2012-03-01

    We reconstructed subsurface (˜45-200 m water depth) temperature variability in the eastern Antarctic continental margin during the late Holocene, using an archaeal lipid-based temperature proxy (TEX86L). Our results reveal that subsurface temperature changes were probably positively coupled to the variability of warmer, nutrient-rich Modified Circumpolar Deep Water (MCDW, deep water of the Antarctic circumpolar current) intrusion onto the continental shelf. The TEX86L record, in combination with previously published climatic records, indicates that this coupling was probably related to the thermohaline circulation, seasonal variability in sea ice extent, sea temperature, and wind associated with high frequency climate dynamics at low-latitudes such as internal El Niño Southern Oscillation (ENSO). This in turn suggests a linkage between centennial ENSO-like variability at low-latitudes and intrusion variability of MCDW into the eastern Antarctic continental shelf, which might have further impact on ice sheet evolution.

  19. Variable Temperature Total AC Loss and Stability Characterization Facility

    Microsoft Academic Search

    Sastry Pamidi; Doan Nguyen; Guomin Zhang; David Knoll; Ulf Trociewitz; Justin Schwartz

    2007-01-01

    The design of a versatile ac loss and stability characterization facility for high temperature superconducting materials suitable for variable temperature measurements is described. A non-metallic vessel inside a transverse field double-helix magnet acts as the measurement chamber. A cryocooler cools the samples to a target measurement temperature between 35 and 80 K. The facility is suitable for measurements on samples

  20. Contribution of solar radiation to decadal temperature variability over land.

    PubMed

    Wang, Kaicun; Dickinson, Robert E

    2013-09-10

    Global air temperature has become the primary metric for judging global climate change. The variability of global temperature on a decadal timescale is still poorly understood. This paper examines further one suggested hypothesis, that variations in solar radiation reaching the surface (Rs) have caused much of the observed decadal temperature variability. Because Rs only heats air during the day, its variability is plausibly related to the variability of diurnal temperature range (daily maximum temperature minus its minimum). We show that the variability of diurnal temperature range is consistent with the variability of Rs at timescales from monthly to decadal. This paper uses long comprehensive datasets for diurnal temperature range to establish what has been the contribution of Rs to decadal temperature variability. It shows that Rs over land globally peaked in the 1930s, substantially decreased from the 1940s to the 1970s, and changed little after that. Reduction of Rs caused a reduction of more than 0.2 °C in mean temperature during May to October from the 1940s through the 1970s, and a reduction of nearly 0.2 °C in mean air temperature during November to April from the 1960s through the 1970s. This cooling accounts in part for the near-constant temperature from the 1930s into the 1970s. Since then, neither the rapid increase in temperature from the 1970s through the 1990s nor the slowdown of warming in the early twenty-first century appear to be significantly related to changes of Rs. PMID:23980136

  1. Variable temperature electrochemical strain microscopy of Sm-doped ceria

    SciTech Connect

    Jesse, Stephen [ORNL; Morozovska, A. N. [National Academy of Science of Ukraine, Kiev, Ukraine; Kalinin, Sergei V [ORNL; Eliseev, E. A. [National Academy of Science of Ukraine, Kiev, Ukraine; Yang, Nan [ORNL; Doria, Sandra [ORNL; Tebano, Antonello [ORNL

    2013-01-01

    Variable temperature electrochemical strain microscopy has been used to study the electrochemical activity of Sm-doped ceria as a function of temperature and bias. The electrochemical strain microscopy hysteresis loops have been collected across the surface at different temperatures and the relative activity at different temperatures has been compared. The relaxation behavior of the signal at different temperatures has been also evaluated to relate kinetic process during bias induced electrochemical reactions with temperature and two different kinetic regimes have been identified. The strongly non-monotonic dependence of relaxation behavior on temperature is interpreted as evidence for water-mediated mechanisms.

  2. Latitudinal variation in the occurrence of GPS L-band scintillations associated with the day-to-day changes in TEC, h'F and the E×B drift velocity and their impact on GPS satellite signals

    NASA Astrophysics Data System (ADS)

    Venkatesh, K.; Rao, P. V. S. Rama; Seemala, Gopi K.; Prasad, D. S. V. V. D.

    2015-04-01

    The present study describes the day-to-day variations in the occurrence of GPS L-band scintillations from equator to the anomaly crest location associated with the changes in TEC, hF and E ×B drift velocities. The GPS-TEC and S4 index data from an equatorial station, Trivandrum (8.47?N, 76.91?E), a low latitude station, Waltair (17.7?N, 83.3?E) and an anomaly crest location Kolkata (22.6?N, 88.4?E) during the low solar activity years of 2004 and 2005 are used. It is observed that the day-time ambient TEC is higher during scintillation days compared to that during the days on which there are no scintillations at the three different locations mentioned above. Further, the diurnal variation of TEC shows a rapid decay during 1700-2000 hr LT over the three different locations during scintillation days which is observed to be comparatively much less during no scintillation days. The average height of the F-layer in the post-sunset hours over Trivandrum is found to be higher, around 350 km during scintillation days while it is around 260 km during the days on which there is no scintillation activity. The average pre-reversal E ×B drift velocity observed around 19:00 hr LT is higher (20 m/s) during scintillation days, whereas during no scintillation days, it is found to be much less (7 m/s). Further, it is observed that the GPS receivers lose their locks whenever the S4 index exceeds 0.5 (>10 dB power level) and these loss of lock events are observed to be more around the anomaly crest location (Kolkata). It may be inferred from the present observations that the level of ambient ionization around noon-time, and a fast decay (collapse) of the ionization during afternoon hours followed by rapid increase in the height of the F-layer contributes significantly to the occurrence of scintillations. The present study further indicates that the S4 index at L-band frequencies increases with an increase in latitude maximizing around the crest of the equatorial ionization anomaly during the post-sunset hours resulting in more loss of lock events in the GPS receiver signals around the EIA crest region.

  3. Latitudinal variation in the occurrence of GPS L-band scintillations associated with the day-to-day changes in TEC, h'F and the E×B drift velocity and their impact on GPS satellite signals

    NASA Astrophysics Data System (ADS)

    Venkatesh, K.; Rao, P. V. S. Rama; Seemala, Gopi K.; Prasad, D. S. V. V. D.

    2015-04-01

    The present study describes the day-to-day variations in the occurrence of GPS L-band scintillations from equator to the anomaly crest location associated with the changes in TEC, h ^' }F and E ×B drift velocities. The GPS-TEC and S4 index data from an equatorial station, Trivandrum (8.47?N, 76.91?E), a low latitude station, Waltair (17.7?N, 83.3?E) and an anomaly crest location Kolkata (22.6?N, 88.4?E) during the low solar activity years of 2004 and 2005 are used. It is observed that the day-time ambient TEC is higher during scintillation days compared to that during the days on which there are no scintillations at the three different locations mentioned above. Further, the diurnal variation of TEC shows a rapid decay during 1700-2000 hr LT over the three different locations during scintillation days which is observed to be comparatively much less during no scintillation days. The average height of the F-layer in the post-sunset hours over Trivandrum is found to be higher, around 350 km during scintillation days while it is around 260 km during the days on which there is no scintillation activity. The average pre-reversal E ×B drift velocity observed around 19:00 hr LT is higher (20 m/s) during scintillation days, whereas during no scintillation days, it is found to be much less (7 m/s). Further, it is observed that the GPS receivers lose their locks whenever the S4 index exceeds 0.5 (>10 dB power level) and these loss of lock events are observed to be more around the anomaly crest location (Kolkata). It may be inferred from the present observations that the level of ambient ionization around noon-time, and a fast decay (collapse) of the ionization during afternoon hours followed by rapid increase in the height of the F-layer contributes significantly to the occurrence of scintillations. The present study further indicates that the S4 index at L-band frequencies increases with an increase in latitude maximizing around the crest of the equatorial ionization anomaly during the post-sunset hours resulting in more loss of lock events in the GPS receiver signals around the EIA crest region.

  4. Variable temperature NMR characterization of ?-glycine

    NASA Astrophysics Data System (ADS)

    Taylor, R. E.; Dybowski, C.

    2008-10-01

    Proton NMR spin-lattice relaxation times in the laboratory frame ( T1) and in the rotating frame ( T1?) were measured as a function of temperature for a static sample of ?-glycine. Both T1 and T1? data can be fit quantitatively by a single thermally-activated motion (the modulation of the dipolar coupling by random hopping about the threefold axis of the -NH 3 group), with no addition of other mechanisms at any temperature between 173 and 415 K. An activation energy of 21.7 ± 1 kJ/mol was extracted and is compared with previously reported values for both ?- and ?-glycine. Such comparisons allow the correction of glycine polymorphs misidentified in the literature. The minimum in T1 at 325 K corresponds to a correlation time of 0.53 ns. Chemical shifts as a function of temperature were measured by 1H CRAMPS and by 13C and 15N CP/MAS experiments. These results are discussed relative to a previous report of anomalous electrical behavior in ?-glycine within this temperature range.

  5. Temperature Variability during Delirium in ICU Patients: An Observational Study

    PubMed Central

    van der Kooi, Arendina W.; Kappen, Teus H.; Raijmakers, Rosa J.; Zaal, Irene J.; Slooter, Arjen J. C.

    2013-01-01

    Introduction Delirium is an acute disturbance of consciousness and cognition. It is a common disorder in the intensive care unit (ICU) and associated with impaired long-term outcome. Despite its frequency and impact, delirium is poorly recognized by ICU-physicians and –nurses using delirium screening tools. A completely new approach to detect delirium is to use monitoring of physiological alterations. Temperature variability, a measure for temperature regulation, could be an interesting component to monitor delirium, but whether temperature regulation is different during ICU delirium has not yet been investigated. The aim of this study was to investigate whether ICU delirium is related to temperature variability. Furthermore, we investigated whether ICU delirium is related to absolute body temperature. Methods We included patients who experienced both delirium and delirium free days during ICU stay, based on the Confusion Assessment method for the ICU conducted by a research- physician or –nurse, in combination with inspection of medical records. We excluded patients with conditions affecting thermal regulation or therapies affecting body temperature. Daily temperature variability was determined by computing the mean absolute second derivative of the temperature signal. Temperature variability (primary outcome) and absolute body temperature (secondary outcome) were compared between delirium- and non-delirium days with a linear mixed model and adjusted for daily mean Richmond Agitation and Sedation Scale scores and daily maximum Sequential Organ Failure Assessment scores. Results Temperature variability was increased during delirium-days compared to days without delirium (?unadjusted=0.007, 95% confidence interval (CI)=0.004 to 0.011, p<0.001). Adjustment for confounders did not alter this result (?adjusted=0.005, 95% CI=0.002 to 0.008, p<0.001). Delirium was not associated with absolute body temperature (?unadjusted=-0.03, 95% CI=-0.17 to 0.10, p=0.61). This did not change after adjusting for confounders (?adjusted=-0.03, 95% CI=-0.17 to 0.10, p=0.63). Conclusions Our study suggests that temperature variability is increased during ICU delirium. PMID:24194955

  6. Variable intertidal temperature explains why disease endangers black abalone

    USGS Publications Warehouse

    Ben-Horin, Tal; Lenihan, Hunter S.; Lafferty, Kevin D.

    2013-01-01

    Epidemiological theory suggests that pathogens will not cause host extinctions because agents of disease should fade out when the host population is driven below a threshold density. Nevertheless, infectious diseases have threatened species with extinction on local scales by maintaining high incidence and the ability to spread efficiently even as host populations decline. Intertidal black abalone (Haliotis cracherodii), but not other abalone species, went extinct locally throughout much of southern California following the emergence of a Rickettsiales-like pathogen in the mid-1980s. The rickettsial disease, a condition known as withering syndrome (WS), and associated mortality occur at elevated water temperatures. We measured abalone body temperatures in the field and experimentally manipulated intertidal environmental conditions in the laboratory, testing the influence of mean temperature and daily temperature variability on key epizootiological processes of WS. Daily temperature variability increased the susceptibility of black abalone to infection, but disease expression occurred only at warm water temperatures and was independent of temperature variability. These results imply that high thermal variation of the marine intertidal zone allows the pathogen to readily infect black abalone, but infected individuals remain asymptomatic until water temperatures periodically exceed thresholds modulating WS. Mass mortalities can therefore occur before pathogen transmission is limited by density-dependent factors.

  7. Causes of Greenland temperature variability over the past 4000 years

    NASA Astrophysics Data System (ADS)

    Kobashi, T.; Kawamura, K.; Azuma, K. G.; Box, J. E.; Gao, C.; Nakaegawa, T.

    2012-12-01

    A new Greenland temperature record reconstructed from argon and nitrogen isotopes in trapped air in GISP2 ice core provides high-resolution (< 20 years) and precise temperature estimates over the past 4000 years [Kobashi et al., 2011]. Owing to tight age-controls and abundant paleoclimatic information from the ice core, the record provides a rare opportunity to evaluate the late Holocene climate in a multi-decadal to millennial time scale. In our earlier study [Kobashi et al., Submitted], we found Greenland temperature deviated from North Hemispheric (NH) temperature trend negatively to solar variation over the past 800 years owing to changes in solar-induced atmospheric circulations such as North Atlantic Oscillation/Arctic Oscillation (NAO/AO) with an additional contribution from changes in Atlantic meridional overturning circulation (AMOC). To investigate causes of the Greenland temperature variability over the past 4000 years, we calculated high latitude (75°N) temperature change by a one-dimensional energy balance model with orbital, solar, volcanic, greenhouse gas forcings. The volcanic forcing was reconstructed from GISP2 sulphate record, which agreed sufficiently well with the volcanic forcing reconstruction for NH from multi ice cores [Gao et al., 2008] over the past 1500 years. The result exhibited a secular temperature decrease in northern high latitudes owing to decreasing annual mean insolation by 1.4% through orbital forcing. As the Greenland temperature deviates from North Hemispheric trend negatively by solar variation, we added negative solar signal on the calculated high latitude temperature to infer Greenland temperature, mimicking solar induced NAO/AO and AMOC change of the past 800 years. The calculated Greenland temperature agrees with the ice core derived Greenland temperature with a correlation coefficient of r = 0.3 in a 95 % confidence level, indicating that the past variability of solar activity, volcanic eruptions, greenhouse gasses, and orbital changes can explain at least 9% of multi-decadal to millennial Greenland temperature variability over the past 4000 years. Considering expected large internal variability of regional climate, it is rather remarkable. A millennial cooling around 500 B.C.E. to 0 C.E. observed in Greenland temperature reconstruction from borehole temperature profiles [Dahl-Jensen et al., 1998] were also found in the calculated temperatures, indicating the cooling was caused by several volcanic eruptions and negative responses of Greenland temperature to solar variability. Dahl-Jensen, D., K. Mosegaard, N. Gundestrup, G. D. Clow, S. J. Johnsen, A. W. Hansen, and N. Balling (1998), Past temperatures directly from the Greenland Ice Sheet, Science, 282(5387), 268-271. Gao, C., A. Robock, and C. Ammann (2008), Volcanic forcing of climate over the past 1500 years: An improved ice core-based index for climate models, J. Geophys. Res. - Atmos., 113, D23111. Kobashi, T., D. T. Shindell, K. Kodera, J. E. Box, T. Nakaegawa, and K. Kawamura (Submitted), On the origin of Greenland temperature anomalies over the past 800 years, J. Geophys. Res. Kobashi, T., K. Kawamura, J. P. Severinghaus, J.-M. Barnola, T. Nakaegawa, B. M. Vinther, S. J. Johnsen, and J. E. Box (2011), High variability of Greenland surface temperature over the past 4000 years estimated from trapped air in an ice core, Geophys. Res. Lett., 38(L21501).

  8. Joint variability of global runoff and global sea surface temperatures

    USGS Publications Warehouse

    McCabe, G.J.; Wolock, D.M.

    2008-01-01

    Global land surface runoff and sea surface temperatures (SST) are analyzed to identify the primary modes of variability of these hydroclimatic data for the period 1905-2002. A monthly water-balance model first is used with global monthly temperature and precipitation data to compute time series of annual gridded runoff for the analysis period. The annual runoff time series data are combined with gridded annual sea surface temperature data, and the combined dataset is subjected to a principal components analysis (PCA) to identify the primary modes of variability. The first three components from the PCA explain 29% of the total variability in the combined runoff/SST dataset. The first component explains 15% of the total variance and primarily represents long-term trends in the data. The long-term trends in SSTs are evident as warming in all of the oceans. The associated long-term trends in runoff suggest increasing flows for parts of North America, South America, Eurasia, and Australia; decreasing runoff is most notable in western Africa. The second principal component explains 9% of the total variance and reflects variability of the El Ni??o-Southern Oscillation (ENSO) and its associated influence on global annual runoff patterns. The third component explains 5% of the total variance and indicates a response of global annual runoff to variability in North Aflantic SSTs. The association between runoff and North Atlantic SSTs may explain an apparent steplike change in runoff that occurred around 1970 for a number of continental regions.

  9. Novel Dodecaarylporphyrins: Synthesis and Variable Temperature NMR Studies

    SciTech Connect

    Cancilla, Mark; Lebrilla, Carlito; Ma, Jian-Guo; Medforth, Craig J.; Muzzi, Cinzia M.; Shelnutt, John A.; Smith, Kevin M.; Voss, Lisa

    1999-05-05

    An investigation of the synthesis of novel dodecaarylporphyrins using the Suzuki coupling reaction of arylboronic acids with octabromotetraarylporphyrins is reported. Studies of the dynamic properties of these new porphyrins using variable temperature (VT) 1H NMR spectroscopy and molecular mechanics provide interesting insights into their dynamic properties, including the first determination of {beta} aryl rotation in a porphyrin system.

  10. Orthogonal Wavelet Analysis: Interannual Variability in the Sea Surface Temperature

    Microsoft Academic Search

    Mankin Mak

    1995-01-01

    The unique capability of orthogonal wavelets, which have attractive time-frequency localization properties as exemplified by the Meyer wavelet, is demonstrated in a diagnosis of the interannual variability using a 44-year dataset of the sea surface temperature (SST). This wavelet analysis is performed in conjunction with an empirical orthogonal function analysis and a Fourier analysis to illustrate their complementary capability. The

  11. Decadal scale variability of sea surface temperature in the Mediterranean Sea in relation to atmospheric variability

    Microsoft Academic Search

    Nikolaos Skliris; Sarantis Sofianos; Athanasios Gkanasos; Anneta Mantziafou; Vasilis Vervatis; Panagiotis Axaopoulos; Alex Lascaratos

    2011-01-01

    Twenty-four years of AVHRR-derived sea surface temperature (SST) data (1985-2008) and 35 years of NOCS (V.2) in situ-based SST data (1973-2008) were used to investigate the decadal scale variability of this parameter in the Mediterranean Sea in relation to local air-sea interaction and large-scale atmospheric variability. Satellite and in situ-derived data indicate a strong eastward increasing sea surface warming trend

  12. Analysis and interpretation of variabilities in ozone and temperature fields

    NASA Technical Reports Server (NTRS)

    Chandra, S.

    1990-01-01

    The temporal and spatial variabilities were studied of short and long term fluctuations in stratospheric ozone and temperature at various pressure levels using several years of ozone, temperature, and solar flux data from Nimbus 4, Nimbus 7, and SME satellites. Some results are as follows: (1) the solar UV flux and various indices of solar activity indicate a strong period at about 5 months; (2) satellite total ozone observations were analyzed using 17 years of data from the Nimbus 4 BUV and the Nimbus 7 SBUV experiments, which show very similar seasonal variations and quasibiennial oscillation (QBO) with some indication of a 4 year component; and (3) the zonal characteristics of both the ozone and temperature trends were derived from ten years of total ozone and 50 mb temperature based on the Nimbus 7 TOMS measurements and the NMC analyses respectively.

  13. Temperature variable long path cell for absorption measurements

    NASA Technical Reports Server (NTRS)

    Shetter, R. E.; Davidson, J. A.; Cantrell, C. A.; Calvert, J. G.

    1987-01-01

    The design and construction of a long path cell for absorption measurements at temperatures ranging from 215-470 K and at pressures from vacuum to 10 atm are described. The cell consists of three concentric stainless-steel tubes; the innermost tube is 6.5-in. in internal diameter, has a volume of about 47 l, and contains White-type optics, six thermocouples, and a gas input tube; and the outermost tube provides a vacuum Dewar around the inner assembly. The optical design and temperature control system for the long path temperature variable cell are examined. The long path cell is applicable for analyzing temperature and pressure dependence of spectra and reaction rates of gases, and the cell has flow and photolysis capabilities for studying transient species and photochemically initiated reactions. A diagram of the cell is provided.

  14. Complexation of thorium(IV) with acetate at variable temperatures.

    PubMed

    Rao, Linfeng; Zhang, Zhicheng; Zanonato, PierLuigi; Di Bernardo, Plinio; Bismondo, Arturo; Clark, Sue B

    2004-09-21

    The complexation between Th(IV) and acetate in 1.05 mol kg(-1) NaClO4 was studied at variable temperatures (10, 25, 40, 55 and 70 degrees C). The formation constants of five successive complexes, Th(Ac)j(4-j)+ where Ac = CH3COO- and j = 1-5, and the molar enthalpies of complexation were determined by potentiometry and calorimetry. Extended X-ray absorption fine structure spectroscopy (EXAFS) provided additional information on the complexes in solution. The effect of temperature on the stability of the complexes is discussed in terms of the electrostatic model. PMID:15349159

  15. Quantifying Walker River stream temperature variability using distributed temperature sensing data

    NASA Astrophysics Data System (ADS)

    Beck, A. J.; Null, S. E.

    2014-12-01

    Nevada's Walker River historically supported Lahontan cutthroat trout (Oncorhynchus clarki henshawi), although today Lahontan cutthroat trout are listed as a federally threatened species and limited to isolated headwater reaches. Much of the lower Walker River is impaired for native aquatic species because of elevated stream temperatures and nutrients, and low streamflow and dissolved oxygen levels. We deployed a 1 kilometer single-ended fiber-optic Raman spectra distributed temperature sensing (DTS) cable in the Wabuska drain outlet and surrounding Walker River for one week in June 2014 to improve fine-scale understanding of stream temperatures. These data identify and quantify thermal variability of micro-habitat that standard temperature monitoring and modeling do not capture. Results indicate stream temperatures exceeded 26°C and a return flow channel exhibited greater thermal variability with both warmer daytime temperatures and cooler nighttime temperatures - possibly providing more complex thermal habitat during some flow conditions. Fine-scale DTS data complement ongoing stream temperature modeling by bounding thermal variability within model reaches that are 250 m long and where stream temperature is assumed to be well-mixed within each reach.

  16. Material variability as measured by low temperature electrical resistivity.

    NASA Technical Reports Server (NTRS)

    Clark, A. F.; Tryon, P. V.

    1972-01-01

    Low temperature electrical resistivity was used to determine the material variability (1) between different manufacturers, (2) between different heats from the same manufacturer, and (3) within a given heat for Al 2024, Al-5% Mg alloys, Inconel 718, A286 stainless, and AISI 316. Generally, the coefficient of variation for solution annealed alloys ranged from 1.2 to 14% between manufacturers, 0.8 to 5.1% between heats, and 0.1 to 1.6% within a heat with stainless steels at the low ends and Al 2024 at the high ends. The variability is increased if the material is in a precipitation-hardened condition. A statistical analysis suggests that the variability within a heat is non-normal.

  17. Central England temperature and sunspot variability 1660–1975

    Microsoft Academic Search

    C. D. Schönwiese

    1978-01-01

    Summary  Mean annual values of Central England air temperature near the ground and sunspot relative numbers for the time interval 1660–1975 are investigated and compared by statistical means in order to analyse their variability in relation to time and frequency (period). Spectral analyses of variance indicate dominant variance components of about 2.15, 3.1, 3.4, 5.1, 25 and 100a (a=year) in the

  18. Historical Temperature Variability Affects Coral Response to Heat Stress

    PubMed Central

    Carilli, Jessica; Donner, Simon D.; Hartmann, Aaron C.

    2012-01-01

    Coral bleaching is the breakdown of symbiosis between coral animal hosts and their dinoflagellate algae symbionts in response to environmental stress. On large spatial scales, heat stress is the most common factor causing bleaching, which is predicted to increase in frequency and severity as the climate warms. There is evidence that the temperature threshold at which bleaching occurs varies with local environmental conditions and background climate conditions. We investigated the influence of past temperature variability on coral susceptibility to bleaching, using the natural gradient in peak temperature variability in the Gilbert Islands, Republic of Kiribati. The spatial pattern in skeletal growth rates and partial mortality scars found in massive Porites sp. across the central and northern islands suggests that corals subject to larger year-to-year fluctuations in maximum ocean temperature were more resistant to a 2004 warm-water event. In addition, a subsequent 2009 warm event had a disproportionately larger impact on those corals from the island with lower historical heat stress, as indicated by lower concentrations of triacylglycerol, a lipid utilized for energy, as well as thinner tissue in those corals. This study indicates that coral reefs in locations with more frequent warm events may be more resilient to future warming, and protection measures may be more effective in these regions. PMID:22479626

  19. Trends and variability in East African rainfall and temperature observations

    NASA Astrophysics Data System (ADS)

    Seregina, Larisa; Ermert, Volker; Fink, Andreas H.; Pinto, Joaquim G.

    2014-05-01

    The economy of East Africa is highly dependent on agriculture, leading to a strong vulnerability of local society to fluctuations in seasonal rainfall amounts, including extreme events. Hence, the knowledge about the evolution of seasonal rainfall under future climate conditions is crucial. Rainfall regimes over East Africa are influenced by multiple factors, including two monsoon systems, several convergence zones and the Rift Valley lakes. In addition, local conditions, like topography, modulate the large-scale rainfall pattern. East African rainfall variability is also influenced by various teleconnections like the Indian Ocean Zonal Mode and El Niño Southern Oscillation. Regarding future climate projections, regional and global climate models partly disagree on the increase or decrease of East African rainfall. The specific aim of the present study is the acquirement of historic data from weather stations in East Africa (Kenya, Tanzania, Ruanda and Uganda), the use of gridded satellite (rainfall) products (ARC2 and TRMM), and three-dimensional atmospheric reanalysis (e.g., ERA-Interim) to quantify climate variability in the recent past and to understand its causes. Climate variability and trends, including changes in extreme events, are evaluated using ETCCDI climate change and standardized precipitation indices. These climate indices are determined in order to investigate the variability of temperature and rainfall and their trends with the focus on most recent decades. In the follow-up, statistical and dynamical analyses are conducted to quantify the local impact of pertinent large-scale modes of climate variability (Indian Ocean Zonal Mode, El Niño Southern Oscillation, Sea Surface Temperature of the Indian Ocean).

  20. The influence of global sea surface temperature variability on the large-scale land surface temperature

    NASA Astrophysics Data System (ADS)

    Tyrrell, Nicholas L.; Dommenget, Dietmar; Frauen, Claudia; Wales, Scott; Rezny, Mike

    2015-04-01

    In global warming scenarios, global land surface temperatures () warm with greater amplitude than sea surface temperatures (SSTs), leading to a land/sea warming contrast even in equilibrium. Similarly, the interannual variability of is larger than the covariant interannual SST variability, leading to a land/sea contrast in natural variability. This work investigates the land/sea contrast in natural variability based on global observations, coupled general circulation model simulations and idealised atmospheric general circulation model simulations with different SST forcings. The land/sea temperature contrast in interannual variability is found to exist in observations and models to a varying extent in global, tropical and extra-tropical bands. There is agreement between models and observations in the tropics but not the extra-tropics. Causality in the land-sea relationship is explored with modelling experiments forced with prescribed SSTs, where an amplification of the imposed SST variability is seen over land. The amplification of to tropical SST anomalies is due to the enhanced upper level atmospheric warming that corresponds with tropical moist convection over oceans leading to upper level temperature variations that are larger in amplitude than the source SST anomalies. This mechanism is similar to that proposed for explaining the equilibrium global warming land/sea warming contrast. The link of the to the dominant mode of tropical and global interannual climate variability, the El Niño Southern Oscillation (ENSO), is found to be an indirect and delayed connection. ENSO SST variability affects the oceans outside the tropical Pacific, which in turn leads to a further, amplified and delayed response of.

  1. Performance measurements of multilayer insulation at variable cold temperature

    NASA Astrophysics Data System (ADS)

    Funke, Thomas; Haberstroh, Christoph

    2012-06-01

    Multilayer insulation (MLI) is commonly used in most cryogenic devices such as LHe-cryostats or superconductive cables. Typically thermal performance measurements have been carried out using bath cryostats. Inherent to all this devices is a fixed cold temperature at the boiling point of the particular cryogenic liquid. A recent approach for cryogenic pressure vessels covers a broad temperature range, i.e. hydrogen storage from 20 K to ambient temperature. Thus, a new calorimeter cryostat has been designed at TU Dresden to meet these requirements. The design as a flow cryostat allows the measurement of the thermal performance with variable cold temperature between 20 K and 300 K. It can be operated in vertical as well as in horizontal orientation. The insulation material is wrapped around a nearly isothermal cylinder which is held at the desired temperature by a cooling fluid. Preferably LHe respectively helium cold gas is used. Several design features reduce undesired interference errors. It is reported about design and equipment of this cryostat plus first experiences in operation

  2. Variability of Winter Air Temperature in Mid-Latitude Europe

    NASA Technical Reports Server (NTRS)

    Otterman, J.; Ardizzone, J.; Atlas, R.; Bungato, D.; Cierniewski, J.; Jusem, J. C.; Przybylak, R.; Schubert, S.; Starr, D.; Walczewski, J.

    2002-01-01

    The aim of this paper is to report extreme winter/early-spring air temperature (hereinafter temperature) anomalies in mid-latitude Europe, and to discuss the underlying forcing to these interannual fluctuations. Warm advection from the North Atlantic in late winter controls the surface-air temperature, as indicated by the substantial correlation between the speed of the surface southwesterlies over the eastern North Atlantic (quantified by a specific Index Ina) and the 2-meter level air temperatures (hereinafter Ts) over Europe, 45-60 deg N, in winter. In mid-March and subsequently, the correlation drops drastically (quite often it is negative). This change in the relationship between Ts and Ina marks a transition in the control of the surface-air temperature: absorption of insolation replaces the warm advection as the dominant control. This forcing by maritime-air advection in winter was demonstrated in a previous publication, and is re-examined here in conjunction with extreme fluctuations of temperatures in Europe. We analyze here the interannual variability at its extreme by comparing warm-winter/early-spring of 1989/90 with the opposite scenario in 1995/96. For these two December-to-March periods the differences in the monthly mean temperature in Warsaw and Torun, Poland, range above 10 C. Short-term (shorter than a month) fluctuations of the temperature are likewise very strong. We conduct pentad-by-pentad analysis of the surface-maximum air temperature (hereinafter Tmax), in a selected location, examining the dependence on Ina. The increased cloudiness and higher amounts of total precipitable water, corollary effects to the warm low-level advection. in the 1989/90 winter, enhance the positive temperature anomalies. The analysis of the ocean surface winds is based on the Special Sensor Microwave/Imager (SSM/I) dataset; ascent rates, and over land wind data are from the European Centre for Medium-Range Weather Forecasts (ECMWF); maps of 2-m temperature, cloud cover and precipitable water are from the National Centers for Environmental Prediction (NCEP) Reanalysis.

  3. Complexation of Plutonium (IV) With Sulfate At Variable Temperatures

    SciTech Connect

    Y. Xia; J.I. Friese; D.A> Moore; P.P. Bachelor; L. Rao

    2006-10-05

    The complexation of plutonium(IV) with sulfate at variable temperatures has been investigated by solvent extraction method. A NaBrO{sub 3} solution was used as holding oxidant to maintain the plutonium(IV) oxidation state throughout the experiments. The distribution ratio of Pu(IV) between the organic and aqueous phases was found to decrease as the concentrations of sulfate were increased. Stability constants of the 1:1 and 1:2 Pu(IV)-HSO{sub 4}{sup -} complexes, dominant in the aqueous phase, were calculated from the effect of [HSO{sub 4}{sup -}] on the distribution ratio. The enthalpy and entropy of complexation were calculated from the stability constants at different temperatures using the Van't Hoff equation.

  4. Quiescent climate models or noisy proxies: comparing observed and simulated Holocene temperature variability

    NASA Astrophysics Data System (ADS)

    Laepple, Thomas; Huybers, Peter

    2015-04-01

    Determining magnitudes of climate variability is important for attributing past and predicting future changes in climate. Multidecadal and longer temperature variability is poorly constrained, however, primarily because instrumental records are short and proxy records are noisy. Using a global compilation of Holocene marine temperature proxy records and correcting for non-climate variability, we derive an estimate for regional temperature variability between annual and millennial time-scales. Our estimate of temperature variability is consistent between different proxy types and with instrumental records. In comparison, general circulation model simulations have systematically less temperature variability than instrumental and proxy-based estimates. Discrepancies in variability are largest at low latitudes and increase with timescale, reaching two orders of magnitude for tropical variability at millennial timescales. This poster will summarize our recent efforts to estimate Holocene temperature variability and to understand the sources of the discrepancy between simulated and proxy-based Holocene variability estimates.

  5. Adapting to the Day to Day Growth of TMR

    PubMed Central

    Hammond, William E.; Stead, William W.; Straube, Mark J.; Hammond, William E.

    1983-01-01

    Data capacity requirements vary widely as user groups vary in their use of and dependence on a computerized medical record. The development of TMR has fortunately been able to satisfy growth demands by adapting either application programs or system programs to remove growth restrictions as they are identified. This paper describes that evolution.

  6. Interannual variability in sea surface temperature and fCO2 changes in the Cariaco Basin

    E-print Network

    Meyers, Steven D.

    Interannual variability in sea surface temperature and fCO2 changes in the Cariaco Basin Y.M. Astor temperature Climate variability a b s t r a c t We examined the variability of sea surface carbon dioxide trend in monthly- deseasonalized sea surface temperatures (SST) was observed, leading to an overall

  7. High Temperature Variable Conductance Heat Pipes for Radioisotope Stirling Systems

    NASA Technical Reports Server (NTRS)

    Tarau, Calin; Walker, Kara L.; Anderson, William G.

    2009-01-01

    In a Stirling radioisotope system, heat must continually be removed from the GPHS modules, to maintain the GPHS modules and surrounding insulation at acceptable temperatures. Normally, the Stirling convertor provides this cooling. If the Stirling convertor stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS, but also ending the mission. An alkali-metal Variable Conductance Heat Pipe (VCHP) is under development to allow multiple stops and restarts of the Stirling convertor. The status of the ongoing effort in developing this technology is presented in this paper. An earlier, preliminary design had a radiator outside the Advanced Stirling Radioisotope Generator (ASRG) casing, used NaK as the working fluid, and had the reservoir located on the cold side adapter flange. The revised design has an internal radiator inside the casing, with the reservoir embedded inside the insulation. A large set of advantages are offered by this new design. In addition to reducing the overall size and mass of the VCHP, simplicity, compactness and easiness in assembling the VCHP with the ASRG are significantly enhanced. Also, the permanently elevated temperatures of the entire VCHP allows the change of the working fluid from a binary compound (NaK) to single compound (Na). The latter, by its properties, allows higher performance and further mass reduction of the system. Preliminary design and analysis shows an acceptable peak temperature of the ASRG case of 140 C while the heat losses caused by the addition of the VCHP are 1.8 W.

  8. Spatial and Seasonal Variability of Extreme Soil Temperature in Croatia

    NASA Astrophysics Data System (ADS)

    Svili?i?, Petra; Vu?eti?, Višnja

    2015-04-01

    In terms of taking the temperature of the Earth in Croatia, first measurements began in 1898 in Križevci, but systematic measurements of soil temperature started in 1951. Today, the measurements are performed at 55 meteorological stations. The process of setting up, calibration, measurement, input, control and data processing is done entirely within the Meteorological and Hydrological Service. Due to the lack of funds, but also as a consequence of the Homeland War, network density in some areas is very rare, leading to aggravating circumstances during analysis. Also, certain temperature series are incomplete or are interrupted and therefore the number of long-term temperature series is very small. This particularly presents problems in coastal area, which is geographically diversified and is very difficult to do a thorough analysis of the area. Using mercury angle geothermometer daily at 7, 14 and 21 h CET, thermal state of soil is measured at 2, 5, 10, 20, 30, 50 and 100 cm depth. Thermometers are placed on the bare ground within the meteorological circle and facing north to reduce the direct impact of solar radiation. Lack of term measurements is noticed in the analysis of extreme soil temperatures, which are not real extreme values, but derived from three observational times. On the basis of fifty year series (1961-2010) at 23 stations, the analysis of trends of the surface maximal and minimal soil temperature, as well as the appearance of freezing is presented. Trends were determined by Sen's slope estimator, and statistical significance on 5% level was determined using the Mann-Kendall test. It was observed that the variability of the surface maximal soil temperature on an annual and seasonal level is much higher than those for surface minimal soil temperature. Trends in the recent period show a statistically significant increase in the maximal soil temperature in the eastern and the coastal regions, especially in the spring and summer season. Also, the average duration of the period in which soil freezing occurs did not change between the recent period (1981-2010) and the standard climatological period (1961-1990). However, first freezing occurs later in the recent period, and the last day of freezing has not changed. Data requirements for the soil temperature come from different users. In agriculture it is very important to know the starting date of sowing, which is largely determined from the thermal state of the soil surface. Also, soil temperature plays a key role in heat stress for plants that cannot tolerate prolonged high or low temperatures. Freezing of the ground is very important in agriculture and construction. The soil can squeeze out more damaged plants which can thus be exposed to drying. In the construction industry, swelling and uplift of the soil can occur during water collecting and creation of ice lenses during the winter period. Also, the freezing of the soil is essential when setting up the gas pipeline, water pipes and underground cables.

  9. Interdiurnal temperature variability over the conterminous United States and Canada 

    E-print Network

    Rice, Peter Bruce

    1988-01-01

    increases (MITV to MITV-N to MITV-Y) as stated previously by Griffiths and Driscoll ( 1982). In Figure 18, NITV values range from 1. 8 to 4. 5'C while MITV-M values range from 0. 5'C to 1. 2'C and NITV-Y values from 0. IO to 0. 40'C. Third, there is a..., the variability of temperature does decrease as the averaging period increases. The average difference from MITV to MITV-M for the 91 stations (n = 91) is 2. 4'C, whereas from MITV-M to MITV-Y is 0, 5'C. The average ratio MITV/MITV-M for the 91 stations (n = 91...

  10. Processes of India's offshore summer intraseasonal sea surface temperature variability

    NASA Astrophysics Data System (ADS)

    Kurian, Nisha; Lengaigne, Matthieu; Vissa, Gopalakrishna Venkata; Vialard, Jerome; Pous, Stephane; Peter, Anne-Charlotte; Durand, Fabien; Naik, Shweta

    2013-04-01

    Active and break phases of the Indian summer monsoon are associated with sea surface temperature (SST) fluctuations at 30-90 days timescale in the Arabian Sea and Bay of Bengal. Mechanisms responsible for basin-scale intraseasonal SST variations have previously been discussed, but the maxima of SST variability are actually located in three specific offshore regions: the South-Eastern Arabian Sea (SEAS), the Southern Tip of India (STI) and the North-Western Bay of Bengal (NWBoB). In the present study, we use an eddy-permitting 0.25° regional ocean model to investigate mechanisms of this offshore intraseasonal SST variability. Modelled climatological mixed layer and upper thermocline depth are in very good agreement with estimates from three repeated expendable bathythermograph transects perpendicular to the Indian Coast. The model intraseasonal forcing and SST variability agree well with observed estimates, although modelled intraseasonal offshore SST amplitude is undere-stimated by 20-30 %. Our analysis reveals that surface heat flux variations drive a large part of the intraseasonal SST variations along the Indian coastline while oceanic processes have contrasted contributions depending of the region considered. In the SEAS, this contribution is very small because intraseasonal wind variations are essentially cross-shore, and thus not associated with significant upwelling intraseasonal fluctuations. In the STI, vertical advection associated with Ekman pumping contributes to ˜30 % of the SST fluctuations. In the NWBoB, vertical mixing diminishes the SST variations driven by the atmospheric heat flux perturbations by 40 %. Simple slab ocean model integrations show that the amplitude of these intraseasonal SST signals is not very sensitive to the heat flux dataset used, but more sensitive to mixed layer depth.

  11. Forcing, feedback and internal variability in global temperature trends.

    PubMed

    Marotzke, Jochem; Forster, Piers M

    2015-01-29

    Most present-generation climate models simulate an increase in global-mean surface temperature (GMST) since 1998, whereas observations suggest a warming hiatus. It is unclear to what extent this mismatch is caused by incorrect model forcing, by incorrect model response to forcing or by random factors. Here we analyse simulations and observations of GMST from 1900 to 2012, and show that the distribution of simulated 15-year trends shows no systematic bias against the observations. Using a multiple regression approach that is physically motivated by surface energy balance, we isolate the impact of radiative forcing, climate feedback and ocean heat uptake on GMST--with the regression residual interpreted as internal variability--and assess all possible 15- and 62-year trends. The differences between simulated and observed trends are dominated by random internal variability over the shorter timescale and by variations in the radiative forcings used to drive models over the longer timescale. For either trend length, spread in simulated climate feedback leaves no traceable imprint on GMST trends or, consequently, on the difference between simulations and observations. The claim that climate models systematically overestimate the response to radiative forcing from increasing greenhouse gas concentrations therefore seems to be unfounded. PMID:25631444

  12. Sea surface temperature variability in Panamá and Galápagos: Extreme temperatures causing coral bleaching

    Microsoft Academic Search

    Guillermo P. Podestfi; Peter W. Glynn

    1997-01-01

    We examined associations between warm sea surface temperature (SST) anomalies and coral bleaching in the Galfipagos Islands and the Gulf of Panamfi, in the tropical eastern Pacific Ocean. Interannual SST variability is dominated by the E1 Nifio-Southern Oscillation phenomenon at Galfipagos, whereas only strong events have an SST signature in Panamfi. We explored various SST-related metrics potentially associated with bleaching

  13. Decadal scale variability of sea surface temperature in the Mediterranean Sea in relation to atmospheric variability

    NASA Astrophysics Data System (ADS)

    Skliris, Nikolaos; Sofianos, Sarantis; Gkanasos, Athanasios; Mantziafou, Anneta; Vervatis, Vasilis; Axaopoulos, Panagiotis; Lascaratos, Alex

    2012-01-01

    Twenty-four years of AVHRR-derived sea surface temperature (SST) data (1985-2008) and 35 years of NOCS (V.2) in situ-based SST data (1973-2008) were used to investigate the decadal scale variability of this parameter in the Mediterranean Sea in relation to local air-sea interaction and large-scale atmospheric variability. Satellite and in situ-derived data indicate a strong eastward increasing sea surface warming trend from the early 1990s onwards. The satellite-derived mean annual warming rate is about 0.037°C year-1 for the whole basin, about 0.026°C year-1 for the western sub-basin and about 0.042°C year-1 for the eastern sub-basin over 1985-2008. NOCS-derived data indicate similar variability but with lower warming trends for both sub-basins over the same period. The long-term Mediterranean SST spatiotemporal variability is mainly associated with horizontal heat advection variations and an increasing warming of the Atlantic inflow. Analysis of SST and net heat flux inter-annual variations indicates a negative correlation, with the long-term SST increase, driving a net air-sea heat flux decrease in the Mediterranean Sea through a large increase in the latent heat loss. Empirical orthogonal function (EOF) analysis of the monthly average anomaly satellite-derived time series showed that the first EOF mode is associated with a long-term warming trend throughout the whole Mediterranean surface and it is highly correlated with both the Eastern Atlantic (EA) pattern and the Atlantic Multidecadal Oscillation (AMO) index. On the other hand, SST basin-average yearly anomaly and NAO variations show low and not statistically significant correlations of opposite sign for the eastern (negative correlation) and western (positive correlation) sub-basins. However, there seems to be a link between NAO and SST decadal-scale variations that is particularly evidenced in the second EOF mode of SST anomalies. NOCS SST time series show a significant SST rise in the western basin from 1973 to the late 1980s following a large warming of the inflowing surface Atlantic waters and a long-term increase of the NAO index, whereas SST slowly increased in the eastern basin. In the early 1990s, there is an abrupt change from a very high positive to a low NAO phase which coincides with a large change in the SST spatiotemporal variability pattern. This pronounced variability shift is followed by an acceleration of the warming rate in the Mediterranean Sea and a change in the direction (from westward to eastward) of its spatial increasing tendency.

  14. Variable temperature system using vortex tube cooling and fiber optic temperature measurement for low temperature magic angle spinning NMR.

    PubMed

    Martin, Rachel W; Zilm, Kurt W

    2004-06-01

    We describe the construction and operation of a variable temperature (VT) system for a high field fast magic angle spinning (MAS) probe. The probe is used in NMR investigations of biological macromolecules, where stable setting and continuous measurement of the temperature over periods of several days are required in order to prevent sample overheating and degradation. The VT system described is used at and below room temperature. A vortex tube is used to provide cooling in the temperature range of -20 to 20 degrees C, while a liquid nitrogen-cooled heat exchanger is used below -20 degrees C. Using this arrangement, the lowest temperature that is practically achievable is -140 degrees C. Measurement of the air temperature near the spinning rotor is accomplished using a fiber optic thermometer that utilizes the temperature dependence of the absorption edge of GaAs. The absorption edge of GaAs also has a magnetic field dependence that we have measured and corrected for. This dependence was calibrated at several field strengths using the well-known temperature dependence of the (1)H chemical shift difference of the protons in methanol. PMID:15140428

  15. Long-term trends and interannual variability of temperature in Drake Passage Janet Sprintall

    E-print Network

    Sprintall, Janet

    of variability have been limited to studying sea surface temperature (SST; Niño Southern Oscillation. Variability in sea ice and temperature anomalies lag El Niño variability in the Pacific, with a phasing con- sistent with the observed cyclical patterns of sea ice and sea surface

  16. A High Temperature Hermetic Primer and a Variable Spring Tester

    SciTech Connect

    Begeal, D.R.

    1994-05-01

    Percussion primers are used at Sandia to ignite energetic components such as pyrotechnic actuators and thermal batteries. This report describes a High Temperature Hermetic Primer (HTHP) that was developed to replace a previous G16 Percussion Primer Subassembly (Gl6PPS). The ignition mix in these primers is the same as in the discontinued Remington 44G16 (KC1O{sub 3}, SbS{sub 3}, and Ca{sub 2}Si). The HTHP has nearly the same sensitivity as the 44G16 and a significantly lower sensitivity than the G16PPS. In parallel with the HTHP development, we also designed a Variable Spring Tester (VST) to determine percussion primer ignition sensitivity with firing pins that have the same mass as those used in field applications. The tester is capable of accelerating firing pins over a velocity range of 100 to 600 inches per second for pins weighing up to 6 grams. The desired impulse can be preselected with an accuracy of better than {plus_minus}1%. The actual impulse is measured on every shot. The VST was characterized using the WW42Cl primer, as well as with the G16PPS and the HTHP. Compared to data from conventional ball drop testers, we found that ignition sensitivities were lower and there was less scatter in the sensitivity data. Our experiments indicate that ignition sensitivity is not strictly energy dependent, but also depends on the rate of deposition, or firing pin velocity in this case. Development results for the HTHP and Variable Spring Tester are discussed and design details are shown.

  17. Decadal Modulation of Global Surface Temperature By Internal Climate Variability

    NASA Astrophysics Data System (ADS)

    Dai, A.; Fyfe, J. C.; Xie, S. P.; Dai, X.

    2014-12-01

    Despite a steady increase in atmospheric greenhouse gases (GHGs), global-mean surface temperature (T) has shown no discernable warming since about 2000, in sharp contrast to model simulations which on average project strong warming. The recent slowdown in observed surface warming has been attributed to decadal cooling in the tropical Pacific, intensifying trade winds, changes in El Niño activity, increasing volcanic activity and decreasing solar irradiance. Earlier periods of arrested warming have been observed but received much less attention than the recent period, and their causes are poorly understood. Here we analyze observed and model-simulated global T fields to quantify the contributions of internal climate variability (ICV) to decadal changes in global-mean T since 1920. We show that the Inter-decadal Pacific Oscillation (IPO) has been associated with large T anomalies over both ocean and land since 1920. Combined with another leading mode of ICV, the IPO explains most of the difference between observed and model-simulated rates of decadal change in global-mean T since 1920, and particularly over the so-called "hiatus" period since about 2000. We conclude that ICV, mainly through the IPO, was largely responsible for the recent slowdown, as well as for earlier slowdowns and accelerations in global-mean T since 1920, with preferred spatial patterns different from GHG-induced warming. Recent history suggests that the IPO could reverse course and lead to accelerated global warming in the coming decades.

  18. Decadal modulation of global surface temperature by internal climate variability

    NASA Astrophysics Data System (ADS)

    Dai, Aiguo; Fyfe, John C.; Xie, Shang-Ping; Dai, Xingang

    2015-06-01

    Despite a steady increase in atmospheric greenhouse gases (GHGs), global-mean surface temperature (T) has shown no discernible warming since about 2000, in sharp contrast to model simulations, which on average project strong warming. The recent slowdown in observed surface warming has been attributed to decadal cooling in the tropical Pacific, intensifying trade winds, changes in El Niño activity, increasing volcanic activity and decreasing solar irradiance. Earlier periods of arrested warming have been observed but received much less attention than the recent period, and their causes are poorly understood. Here we analyse observed and model-simulated global T fields to quantify the contributions of internal climate variability (ICV) to decadal changes in global-mean T since 1920. We show that the Interdecadal Pacific Oscillation (IPO) has been associated with large T anomalies over both ocean and land. Combined with another leading mode of ICV, the IPO explains most of the difference between observed and model-simulated rates of decadal change in global-mean T since 1920, and particularly over the so-called `hiatus' period since about 2000. We conclude that ICV, mainly through the IPO, was largely responsible for the recent slowdown, as well as for earlier slowdowns and accelerations in global-mean T since 1920, with preferred spatial patterns different from those associated with GHG-induced warming or aerosol-induced cooling. Recent history suggests that the IPO could reverse course and lead to accelerated global warming in the coming decades.

  19. Method of variable bias and its application to estimating subsurface temperature

    SciTech Connect

    Deming, D.; Hanor, J.S.; Nunn, J.A. (Louisiana State Univ., Baton Rouge (USA))

    1990-10-01

    A method of obtaining variable-bias estimates of physical quantities from noisy and incomplete data is introduced, and its application to estimating subsurface temperature is illustrated by application to temperature data from the Iberia salt dome in south Louisiana.

  20. Evidence of short spatial variability of the equatorial electrojet at close longitudinal separation

    NASA Astrophysics Data System (ADS)

    Chandrasekhar, N. Phani; Arora, Kusumita; Nagarajan, Nandini

    2014-12-01

    The characteristics of longitudinal variability of equatorial electrojet (EEJ) and counter electrojet (CEJ), presented in this study, are based on concurrent observations from a hitherto unsampled region of the world to examine the (1) degree of correlation between hourly means and monthly averaged hourly means of ground observations with equatorial electrojet climatological model (EEJM-2.0), (2) day-to-day longitudinal variability of EEJ strength between the pairs of sites, and (3) longitudinal variability in occurrences of counter electrojet. The analyses are based on the data obtained from an observatory and three new remote sites in the northern Indian Ocean at a longitudinal separation of approximately 15°: Hyderabad (HYB) and Vencode (VEN) at 77° E and Port Blair (PBR) and Campbell Bay (CBY) at 93° E, for a period of 4 months during Lloyd's D-season (November 2011 to February 2012) and comparison with the EEJM-2.0 based on CHAMP satellite data. At both longitudes, the overall correlation of monthly mean hourly values (i.e., from 05:00 to 19:00 LT) between the observed EEJ strength and modeled current density from EEJM-2.0 is good ( r > 0.8). However, a significant lack of correlation is witnessed on day-to-day peak values (i.e., 12:00 LT) between the observed variations and the model at both sites. Further, a comparison of noontime peaks between the two sites shows a considerable day-to-day variability. A large number of CEJs (43 events) are recorded during the study: at CBY (15 events) and VEN (28 events). Analyses of the CEJ events highlight the variability of CEJ phenomena in terms of amplitude, dates, and time of occurrence over 15° longitude separation. The local nature of perturbations causing CEJ is evident; the possible factors are being non-migrating eastward and westward propagating diurnal tides and local meteorological phenomena associated with upper mesospheric temperature, wind, and density variations.

  1. Using Spectral Methods to Quantify Changes in Temperature Variability across Frequencies

    NASA Astrophysics Data System (ADS)

    Sun, S.; McInerney, D.; Stein, M.; Leeds, W.; Poppick, A. N.; Nazarenko, L.; Schmidt, G. A.; Moyer, E. J.

    2014-12-01

    Changes in future surface temperature variability are of great scientific and societal interest. Since the impact of variability on human society depends on not only the magnitude but also the frequency of variations, shifts in the marginal distribution of temperatures do not provide enough information for impacts assessment. Leeds et al (2014) proposed a method to quantify changes in variability of temperature at distinct temporal frequencies by estimating the ratio of the spectral densities of temperature between pre-industrial and equilibrated future climates. This spectral ratio functions well as a metric to quantify temperature variability shifts in climate model output. In this study, we apply the method of Leeds et al (2014) to explore the temperature variability changes under increased radiative forcing. We compare changes in variability in higher-CO2 climates across two different climate models (CCSM3 from the National Center for Atmospheric Research and GISS-E2-R from NASA Goddard Institute for Space Studies), and changes driven by two different forcing agents (CO2 and solar radiation) within the same model (CCSM3). In all cases we use only the equilibrium stages of model runs extended several thousand years after an abrupt forcing change is imposed. We find a number of results. First, changes in temperature variability differ by frequency in most regions, confirming the need for spectral methods. Second, changes are similar regardless of forcing agents. In experiments with abruptly increased CO2 and solar forcing designed to produce the same change in global mean temperature, the distributions and magnitudes of spectral ratio changes are nearly identical. Finally, projections of variability changes differ across models. In CCSM3, temperature variability decreases in most regions and at most frequencies. Conversely, in GISS-E2-R, temperature variability tends to increase over land. The discrepancy between CCSM3 and the GISS-E-R highlights the need for further inter-model comparisons of variability projections. This study provides a potential framework for such comparisons.

  2. A MERRA based analysis of the Climate Variability and Summer Temperature-Rainfall Relationships over India

    Microsoft Academic Search

    S. Fall; D. Niyogi; C. M. Kishtawal; V. Mishra; M. G. Bosilovich; J. K. Entin

    2010-01-01

    Using gridded monthly observation and reanalysis datasets (Modern Era Retrospective-analysis for Research and Applications - MERRA), we examine the variability, co-variability and lagged relationships between temperature and summer rainfall over India (1979 - 2005). The spatial and temporal patterns of temperature and rainfall anomalies are analyzed by computing the percentage of occurrences of positive anomalies for each gridpoint (spatial patterns

  3. Variability and Trends of Air Temperature and Pressure in the Maritime Arctic, 1875-2000

    Microsoft Academic Search

    Igor V. Polyakov; Roman V. Bekryaev; Genrikh V. Alekseev; Uma S. Bhatt; Roger L. Colony; Mark A. Johnson; Alexander P. Maskshtas; David Walsh

    2003-01-01

    Arctic atmospheric variability during the industrial era (1875-2000) is assessed using spatially averaged surface air temperature (SAT) and sea level pressure (SLP) records. Air temperature and pressure display strong multidecadal variability on timescales of 50-80 yr [termed low-frequency oscillation (LFO)]. Associated with this variability, the Arctic SAT record shows two maxima: in the 1930s-40s and in recent decades, with two

  4. The Coordinated Control of a Central Air Conditioning System Based on Variable Chilled Water Temperature and Variable Chilled Water Flow

    E-print Network

    Liu, J.; Mai, Y.; Liu, X.

    2006-01-01

    ICEBO2006, Shenzhen, China Control Systems for Energy Efficiency and Comfort, Vol. V-4-1 The Coordinated Control of a Central Air Conditioning System Based on Variable Chilled Water Temperature and Variable Chilled Water Flow Jinping LIU... Yuebang MAI Xuefeng LIU Associate professor Graduate student Instructor College of Electric Power, South China University of Technology Guangzhou. China Email: mpjpliu@scut.edu.cn Abstract: At present, regulation of water flow by means of pump...

  5. Influence of circulation indices upon winter temperature variability in Egypt

    Microsoft Academic Search

    E. S. Elmallah; S. G. Elsharkawy

    2011-01-01

    Trends of winter surface air temperature anomalies, WSATA, are investigated using data obtained from 13 monitoring stations. The analysis is performed in two steps; one deals with separate stations independently and the other deals with stations' groups. Groups' anomalies are correlated to circulation indices showing negative correlation between temperature with North Atlantic Oscillations and positive one with Mediterranean Oscillation Index.

  6. Comparing variability and trends in observed and modelled globalmean surface temperature

    E-print Network

    land surface temperature and sea surface temperature (SST) datasets [Brohan et al., 2006Comparing variability and trends in observed and modelled globalmean surface temperature John C; accepted 6 July 2010; published 19 August 2010. [1] The observed evolution of the globalmean surface

  7. Tropical sea surface temperature variability near the Oligocene - Miocene boundary

    Microsoft Academic Search

    Y. Zhang; M. Pagani

    2010-01-01

    The Oligocene\\/Miocene (O-M) boundary is characterized by a period of rapid and intense glaciation labeled Mi-1 at ~ 23.1 Ma. An abrupt 1.50\\/00 increase in the benthic foraminifera oxygen isotope composition that characterizes Mi-1 may indicate a (1) significant deep-water temperature decrease; (2) major ice-sheet expansion, or the combination of both. Current coarse Mg\\/Ca-based temperature estimations for the early Miocene

  8. Interdecadal variability of temperature and precipitation in China since 1880

    Microsoft Academic Search

    Shaowu Wang; Jinhong Zhu; Jingning Cai

    2004-01-01

    Reconstruction of a homogeneous temperature and precipitation series for China is crucial for a proper understanding of climate\\u000a change over China. The annual mean temperature anomaly series of ten regions are found from 1880 to 2002. Positive anomalies\\u000a over China during the 1920s and 1940s are noticeable. The linear trend for the period of 1880–2002 is 0.58°C (100a)?1, which is

  9. Variable Temperature Performance of a Si(Li) Detector Stack

    NASA Technical Reports Server (NTRS)

    Hubbard, G. Scott; McMurray, Robert E., Jr.; Keller, R. G.; Wercinski, P. F.; Walton, J. T.; Wong, Y. K.

    1994-01-01

    New experimental data is presented which displays 137Cs resolution of both single Si(Li) devices and a detector stack 2 cm in height as a function of temperature (85 K greater than or equal to T greater than or equal to 245 K). We also discuss variations in photopeak shape which indicate that detector charge collection may be temperature dependent over the range of interest.

  10. Are Room Temperature and Thermal Neutral Synonymous Terms? An Investigation of Common Therapeutic Modality Control Variables

    PubMed Central

    Hawkins, Jeremy R; Knight, Kenneth L; Long, Blaine C

    2007-01-01

    Context: Therapeutic modality control variables are thought to be thermal neutral, a term sometimes used interchangeably with room temperature. We question this common assumption. Objective: To determine thermal neutrality of common therapeutic modality control variables. Design: We performed 5 laboratory experiments, including (1) water temperature over 3 weeks in 3 different containers (glass, plastic, and polystyrene); (2) water temperature and volume of 4 beakers (2 insulated, 2 uninsulated) over 4 weeks, with 1 beaker of each type covered by polyethylene; and skin interface temperature of (3) a dry, nonheated hydrocollator pack held against the chest, (4) kitty litter applied to the knee, and (5) room-temperature ultrasound gel to the forearm. Setting: Therapeutic modalities laboratory. Patients or Other Participants: College student volunteers were subjects in experiments 3, 4, and 5. Main Outcome Measure(s): We measured temperature and volume change. Data were evaluated using descriptive and interferential statistics. Results: Water temperature plateaued significantly below room temperature. Temperatures significantly increased in all but the open, insulated container. Open containers plateaued at approximately 2°C below room temperature and lost significant amounts of water; closed containers plateaued at room temperature with negligible water loss. In experiments 3 through 5, skin temperatures rose significantly during hydrocollator pack, kitty litter, and ultrasound gel application. Conclusions: Room-temperature water baths, dry hydrocollator packs, kitty litter, and ultrasound gel were not thermally neutral. Room temperature should not be used synonymously with thermal neutral. Care must be taken to ensure that control variables truly are controlled. PMID:18059986

  11. Asymmetric trends in seasonal temperature variability based on long instrumental records

    NASA Astrophysics Data System (ADS)

    Matiu, Michael; Ankerst, Donna; Menzel, Annette

    2015-04-01

    While the increase in global mean temperature over the past several decades is widely accepted, the issue as to whether and to what extent temperature variability is changing has not been solved yet. Temperature variability as the width of the temperature distribution measures the likelihood of temperature extremes. Those changes can amplify, nullify or reduce the effect a gradual warming has on extremes. Since climatic extremes exert large impacts on society and ecology, effects of altered temperature variability must be considered in tandem with effects of a gradually increasing temperature mean. Previous studies of trends in mean temperature and its associated variability have produced conflicting results. Here we investigate 10 selected long-term climate records of minimum, mean and maximum temperatures in Switzerland, Germany and the UK. In detail, we analysed trends in seasonal, annual and decadal measures of variability (standard deviation and various quantile ranges) as well as asymmetries in the trends of extreme vs mean temperatures via quantile regression. Besides accelerated mean warming during 1864-2012, we found higher trends for Tmax than for Tmin in the last 40 years (1973-2012), amounting to up to 0.08°C yr-1 in spring. In contrast, variability trends were not as uniform: significant changes occurred in opposing directions depending on the season, as well as when comparing 1864-2012 trends to those of 1973-2012. Often, variability changed asymmetrically and consequently, trends in high and low extremes differed. More patterns were detected for spatial and seasonal variation in these changes of variability.

  12. Variable pressure insulating jackets for high-temperature batteries

    SciTech Connect

    Nelson, P.A.; Chilenskas, A.A.; Malecha, R.F.

    1992-01-01

    A new method is proposed for controlling the temperature of high-temperature batteries namely, varying the hydrogen pressure inside of multifoil insulation by varying the temperature of a reversible hydrogen getter. Calculations showed that the rate of heat loss through 1.5 cm of multifoil insulation between a hot-side temperature of 425[degrees]C and a cold-side temperature of 25[degrees]C could be varied between 17.6 W/m[sup 2] and 7,000 W/m[sup 2]. This change in heat transfer rate can be achieved by varying the hydrogen pressure between 1.0 Pa and 1,000 Pa, which can be done with an available hydrogen gettering alloy operating in the range of 50[degrees]C to 250[degrees]C. This approach to battery cooling requires cylindrical insulating jackets, which are best suited for bipolar batteries having round cells approximately 10 to 18 cm in diameter.

  13. Variable pressure insulating jackets for high-temperature batteries

    SciTech Connect

    Nelson, P.A.; Chilenskas, A.A.; Malecha, R.F.

    1992-12-31

    A new method is proposed for controlling the temperature of high-temperature batteries namely, varying the hydrogen pressure inside of multifoil insulation by varying the temperature of a reversible hydrogen getter. Calculations showed that the rate of heat loss through 1.5 cm of multifoil insulation between a hot-side temperature of 425{degrees}C and a cold-side temperature of 25{degrees}C could be varied between 17.6 W/m{sup 2} and 7,000 W/m{sup 2}. This change in heat transfer rate can be achieved by varying the hydrogen pressure between 1.0 Pa and 1,000 Pa, which can be done with an available hydrogen gettering alloy operating in the range of 50{degrees}C to 250{degrees}C. This approach to battery cooling requires cylindrical insulating jackets, which are best suited for bipolar batteries having round cells approximately 10 to 18 cm in diameter.

  14. Surface air temperature variability in global climate models

    E-print Network

    Davy, Richard

    2012-01-01

    New results from the Coupled Model Inter-comparison Project phase 5 (CMIP5) and multiple global reanalysis datasets are used to investigate the relationship between the mean and standard deviation in the surface air temperature. A combination of a land-sea mask and orographic filter were used to investigate the geographic region with the strongest correlation and in all cases this was found to be for low-lying over-land locations. This result is consistent with the expectation that differences in the effective heat capacity of the atmosphere are an important factor in determining the surface air temperature response to forcing.

  15. Variable-transparency wall regulates temperatures of structures

    NASA Technical Reports Server (NTRS)

    Osullivan, W. J., Jr.

    1964-01-01

    An effective temperature regulating wall consists of one layer /e.g., one of the paraffins/ relatively opaque to thermal radiation in the solid state and transparent to it in the molten state and placed between two transparent layers. A mirror coating is applied to back layer.

  16. Decadal-Scale Temperature Variability in the Southern Ocean

    E-print Network

    Gille, Sarah T.

    neighbor comparisons ship observation 110 km radius 220 km radius float hydrography: SODB (Olbers et al;Nearest Neighbor Comparisons for Profiling Floats · Hydrography: World Ocean Database 2001 data quality pairs at each depth #12;Stratification changes (from PALACE vs Hydrography) #12;Temperature trend

  17. [Parameters of thermoelectric cooling devices in conditions of variable temperatures of the heat-exchange media].

    PubMed

    Efremov, A A; Bratseva, I I

    1985-01-01

    New method for optimized computing thermoelectric coolers is proposed for the case of variable temperatures within heat-transfer media. The operation of the device is analyzed when the temperature of the cooled medium is greater than the temperature of the heated one, i. e. under conditions of the negative temperature difference. The comparative analysis of the computed and experimental data in values of the cooling and electric power demonstrates fully satisfactory results. PMID:3999961

  18. Tropical sea surface temperature variability near the Oligocene - Miocene boundary

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Pagani, M.

    2010-12-01

    The Oligocene/Miocene (O-M) boundary is characterized by a period of rapid and intense glaciation labeled Mi-1 at ~ 23.1 Ma. An abrupt 1.5‰ increase in the benthic foraminifera oxygen isotope composition that characterizes Mi-1 may indicate a (1) significant deep-water temperature decrease; (2) major ice-sheet expansion, or the combination of both. Current coarse Mg/Ca-based temperature estimations for the early Miocene suggests that deep-ocean temperatures were ~2°C warmer than Today [1, 2]. However, Mg/Ca based temperatures can also be influenced by changes in the carbonate ion concentration, vital effects, and diagenesis. In particular, recent evidence from mid-ocean ridge flank carbonate veins shows dramatic seawater Mg/Ca ratio changes during the Neogene (Mg/Ca from ~2.2 to 5.3, [3]), which further challenges the application of Mg/Ca thermometry. Owing to poor temperature constraints, current ice volume estimations for the late Oligocene/early Miocene range from 125% of the present-day East Antarctic Ice Sheet (EAIS) to a nearly complete collapse of the Antarctic glaciers [4]. Here we present tropical sea surface temperatures (SSTs) records based on TEX86 and alkenone UK37 near the O-M boundary. Sediment samples from Ocean Drilling Program (ODP) Site 926 in the Ceara Rise (tropical Atlantic) and Site 1148 in the South China Sea (tropical Pacific) were subject to lipid extraction, separation, gas chromatography, and liquid chromatography-mass spectrometry analysis. TEX86-based SST indicates that the tropics were ~3-4°C warmer than today and relatively stable during Mi-1. This suggests that ice-sheet dynamics, rather than temperature, might be responsible for the observed oxygen isotope changes during the O-M boundary. Further, O-M boundary averaged temperatures recorded at site 926 is ~ 0.5°C higher relative to the late Eocene from site 925 (a nearby site [5]). Given late Oligocene benthic ?18O that suggests at least 1‰ enrichment relative to the late Eocene (e.g. ODP 1218 [2]), our records suggest major Antarctic ice build-up in the Oligocene. Additional work across high-latitude sites is necessary to evaluate how the extratropics responded to climate change during Mi-1, as well as modeling efforts to quantitatively resolve ice volume from temperature. [1] K. Billups, D.P. Schrag, Paleotemperatures and ice volume of the past 27 Myr revisited with paired Mg/Ca and 18O/16O measurements on bethic foraminifera, Paleoceanography 17(2002). [2] C.H. Lear, Y. Rosenthal, H.K. Coxall, P.A. Wilson, Late Eocene to early Miocene ice sheet dynamics and the global carbon cycle, Paleoceanography 19(2004). [3] R.M. Coggon, D.A.H. Teagle, C.E. Smith-Duque, J.C. Alt, M.J. Copper, Reconstructing past seawater Mg/Ca and Sr/Ca from Mid-Ocean Ridge flank calcium carbonate veins, Science 327(2010) 1141-1147. [4] S.F. Pekar, R.M. DeConto, High-resolution ice-volume estimates for the early Miocene: Evidence for a dynamic ice sheet in Antarctica, Palaeogeogr. Palaeoclimatol. Palaeoecol. 231(2006) 101-109. [5] Z. Liu, M. Pagani, D. Zinniker, R. DeConto, M. Huber, H. Brinkhuis, S.R. Shah, R.M. Leckie, A. Pearson, Global Cooling During the Eocene-Oligocene Climate Transition, Science 323(2009) 1187-1190.

  19. Performance Optimization of an Irreversible Heat Pump with Variable-temperature Heat Reservoirs 

    E-print Network

    Huang, Y.; Sun, D.

    2006-01-01

    An irreversible cycle model of a heat pump operating between two variable-temperature heat reservoirs is established and used to analyze the performance of the heat pump affected by heat resistances, heat leakage and internal dissipation...

  20. Performance Optimization of an Irreversible Heat Pump with Variable-temperature Heat Reservoirs

    E-print Network

    Huang, Y.; Sun, D.

    2006-01-01

    An irreversible cycle model of a heat pump operating between two variable-temperature heat reservoirs is established and used to analyze the performance of the heat pump affected by heat resistances, heat leakage and internal dissipation...

  1. Variable temperature effects on release rates of readily soluble nuclides

    SciTech Connect

    Kim, C.L.; Chambre, P.L.; Lee, W.W.L.; Pigford, T.H.

    1988-02-01

    In this paper we study the effect of temperature on the release rate of readily soluble nuclides, as affected by a time-temperature-dependent diffusion coefficient. In this analysis ground water fills the voids in the waste package at t=0 and one percent of the inventories of cesium and iodine are immediately dissolved into the void water. Mass transfer resistance of partly failed container and cladding is conservatively neglected. The nuclides move through the void space into the surrounding rock under a concentration gradient. We use an analytic solution to compute the nuclide concentration in the gap or void, and the mass flux rate into the porous rock. 8 refs., 4 figs.

  2. Complexation of Plutonium (IV) with Fluoride at Variable Temperatures

    SciTech Connect

    Xia, Yuanxian; Rao, Linfeng; Friese, Judah I.; Moore, Dean A.; Bachelor, Paula P.

    2010-02-02

    The complexation of Pu(IV) with fluoride at elevated temperatures was studied by solvent extraction technique. A solution of NaBrO3 was used as holding oxidant to maintain the oxidation state of plutonium throughout the experiments. The distribution ratio of Pu(IV) between the organic and aqueous phases was found to decrease as the concentrations of fluoride were increased. Stability constants of the 1:1 and 1:2 Pu(IV)-F- complexes, dominant in the aqueous phase under the experimental conditions, were calculated from the effect of fluoride ions on the distribution ratio. The thermodynamic parameters, including enthalpy and entropy of complexation between Pu(IV) and fluoride at 25 degrees C - 55 degrees C were calculated from the stability constants at different temperatures by using the Van’t Hoff equation.

  3. Temperature and precipitation variability in the European Alps since 1500

    Microsoft Academic Search

    Carlo Casty; Heinz Wanner; Jürg Luterbacher; Jan Esper; Reinhard Böhm

    2005-01-01

    High-resolution temperature and precipitation variations and their seasonal extremes since 1500 are presented for the European Alps (43.25-48.25°N and 4.25-16.25°E). The spatial resolution of the gridded reconstruction is given by 0.5° × 0.5° and monthly (seasonal) grids are reconstructed back to 1659 (1500-1658). The reconstructions are based on a combination of long instrumental station data and documentary proxy evidence applying

  4. Pacific interdecadal variability in this century's sea surface temperatures

    Microsoft Academic Search

    Yi Chao; Michael Ghil; James C. McWilliams

    2000-01-01

    Analysis of this century's sea surface temperatures over the Pacific Ocean reveals an interdecadal oscillation with a period of 15-20 years. Our results show that the well-known 1976-77 climate regime shift is not unique, but represents one of several phase transitions associated with this interdecadal oscillation, also found around 1924-25, 1941-42, and 1957-58. The oscillation's striking north-south symmetry across the

  5. Multisensor analysis of NDVI, surface temperature and biophysical variables at a mixed grassland site

    Microsoft Academic Search

    S. J. GOETZ

    1997-01-01

    A unique remotely sensed data set derived for a temperate mixed grassland in the central United States was used to test the comparability of a suite of satellite and aircraft sensors, and to characterize temporal variability in the normalized diÄ erence vegetation index (NDVI), retrieved surface radiant temperature (Ts), and surface biophysical variables. The temporal evolution of atmospherically corrected NDVI

  6. Variability of sea surface temperature in the southwestern Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    del Monte-Luna, Pablo; Villalobos, Héctor; Arreguín-Sánchez, Francisco

    2015-07-01

    The seasonal and interannual variability of sea surface temperature (SST) in the southwestern Gulf of Mexico (SGM) is related to changes in atmospheric forcing, subsurface water inputs, advection and surface currents. However, little is known about temperature variability in the gulf on decadal and multidecadal timescales. Temperature time series (1900-2010) were analysed in 36 2°×2° geographic quadrants that covered the SGM. A cluster analysis was applied to the data for the seasonal cycle and for the annual anomalies in each quadrant to describe SST variability, with a special focus on low frequencies (i.e. >10 years). Temperature anomalies were correlated with the identified cyclic components of the Atlantic Multidecadal Oscillation (AMO), and temperature variability in coastal quadrants of the gulf was described using multivariate analysis and harmonic analysys. There is a latitudinal separation of quadrants regading the seasonal cycle and a longitudinal separation in the total variability that is related to the Loop Current. The highest SST correlations were those related to a ~60-year cycle of the AMO and were found on the Yucatan shelf. The ~60-year variability is present in the entire gulf, but signals with periods shorter than ten years are more evident in the northern part. Extrapolation of the dominant sea surface temperature cycles in coastal areas of the gulf, shows that there will be a cooling event in the next 20 years.

  7. Long-term variability in Arctic sea surface temperatures

    NASA Astrophysics Data System (ADS)

    Singh, Rajkumar Kamaljit; Maheshwari, Megha; Oza, Sandip R.; Kumar, Raj

    2013-09-01

    In this study, we used 30 years of an operational sea surface temperature (SST) product, the NOAA Optimum Interpolation (OI) SST Version 2 dataset, to examine variations in Arctic SSTs during the period December 1981-October 2011. We computed annual SST anomalies and interannual trends in SST variations for the period 1982-2010; during this period, marginal (though statistically significant) increases in SSTs were observed in oceanic regions poleward of 60°N. A warming trend is evident over most of the Arctic region, the Beaufort Sea, the Chuckchi Sea, Hudson Bay, the Labrador Sea, the Iceland Sea, the Norwegian Sea, Bering Strait, etc.; Labrador Sea experienced higher temperature anomalies than those observed in other regions. However, cooling trends were observed in the central Arctic, some parts of Baffin Bay, the Kara Sea (south of Novaya Zemlya), the Laptev Sea, the Siberian Sea, and Fram Strait. The central Arctic region experienced a cooling trend only during 1992-2001; warming trends were observed during 1982-1991 and 2002-2010. We also examined a 30-yr (1982-2011) record of summer season (June-July-August) SST variations and a 29-yr (1982-2010) record of September SST variations, the results of which are discussed.

  8. An automated system for the analysis of variable temperature radioluminescence

    NASA Astrophysics Data System (ADS)

    Poolton, N. R. J.; Bulur, E.; Wallinga, J.; Bøtter-Jensen, L.; Murray, A. S.; Willumsen, F.

    2001-09-01

    Radioluminescence (RL, i.e. prompt luminescence emitted during exposure to ionizing radiation) is used for analysing luminescence emission processes and has been proposed as a method for determining received radiation doses in both natural and synthetic radiation dosimeters. We describe here an automated system capable of both multi-sample RL analysis and comparative studies using traditional thermoluminescence (TL) and optically stimulated luminescence (OSL) methods. The radioluminescence unit is intended as an attachment for the existing automated Risø TL-OSL systems; it delivers a dose rate of 4.5 Gy/min to materials such as quartz, using an 80 mCi 90Sr/ 90Y ?-source. The unit enables the measurement of RL in the temperature range 25-500°C using both continuous and pulsed radiation exposures. Measurements are fully automated, allowing up to 48 samples to be measured in any one experimental run. Results from several experiments are presented for two representative dosimeters; natural quartz and artificial Al 2O 3:C. These experiments include investigation of the dose and temperature dependence of RL, pulsed RL, and spectrally resolved RL; comparisons with TL are also made.

  9. Note: A variable temperature cell for spectroscopy of thin films

    NASA Astrophysics Data System (ADS)

    Brock-Nannestad, T.; Nielsen, C. B.; Bak, H. Ø.; Pittelkow, M.

    2013-04-01

    We report the design and construction of a cell that enables precisely controlled measurement of UV/Vis spectra of thin films on transparent substrates at temperatures up to 800 K. The dimensions of the setup are accommodated by a standard Varian Cary 5E spectrophotometer allowing for widespread use in standard laboratory settings. The cell also fits in a Bio-Rad IR-spectrometer. The cell is constructed with an outer water cooled heat shield of aluminum and an inner sample holder with heating element, thermo-resistor and windows, made from nickel coated copper. The cell can operate both in air, and with an inert gas filling. We illustrate the utility of the cell by characterization of three commercially available near infrared absorbers that are commonly used for laser welding of plastics and are known to possess high thermal stability.

  10. Phosphonium chloromercurate room temperature ionic liquids of variable composition.

    PubMed

    Metlen, Andreas; Mallick, Bert; Murphy, Richard W; Mudring, Anja-Verena; Rogers, Robin D

    2013-12-16

    The system trihexyl(tetradecyl)phosphonium ([P66614]Cl)/mercury chloride (HgCl2) has been investigated by varying the stoichiometric ratios from 4:1 to 1:2 (25, 50, 75, 100, 150, and 200 mol % HgCl2). All investigated compositions turn out to give rise to ionic liquids (ILs) at room temperature. The prepared ionic liquids offer the possibility to study the structurally and compositionally versatile chloromercurates in a liquid state at low temperatures in the absence of solvents. [P66614]2[HgCl4] is a simple IL with one discrete type of anion, while [P66614]{HgCl3} (with {} indicating a polynuclear arrangement) is an ionic liquid with a variety of polyanionic species, with [Hg2Cl6](2-) apparently being the predominant building block. [P66614]2[Hg3Cl8] and [P66614][Hg2Cl5] appear to be ILs at ambient conditions but lose HgCl2 when heated in a vacuum. For the liquids with the compositions 4:1 and 4:3, more than two discrete ions can be evidenced, namely, [P66614](+), [HgCl4](2-), and Cl(-) and [P66614](+), [HgCl4](2-), and the polynuclear {HgCl3}(-), respectively. The different stoichiometric compositions were characterized by (199)Hg NMR, Raman- and UV-vis spectroscopy, and cyclic voltammetry, among other techniques, and their densities and viscosities were determined. The [P66614]Cl/HgCl2 system shows similarities to the well-known chloroaluminate ILs (e.g., decrease in viscosity with increasing metal content after addition of more than 0.5 mol of HgCl2/mol [P66614]Cl, increasing density with increasing metal content, and the likely formation of polynuclear/polymeric/polyanionic species) but offer the advantage that they are air and water stable. PMID:24274831

  11. Variable-temperature independently driven four-tip scanning tunneling microscope

    E-print Network

    Hasegawa, Shuji

    temperature down to 7 K, combined with a scanning electron microscope SEM . Four STM tips are mechanically with cooling system and scanning electron microscope SEM that is indispensable to navigate the multitipsVariable-temperature independently driven four-tip scanning tunneling microscope Rei Hobara,a Naoka

  12. Greenland Ice Sheet Surface Air Temperature Variability: 18402007* JASON E. BOX

    E-print Network

    Howat, Ian M.

    Greenland Ice Sheet Surface Air Temperature Variability: 1840­2007* JASON E. BOX Byrd Polar, seasonal, and annual mean Greenland ice sheet near- surface air temperatures. Independent observations Greenland in autumn and southern Greenland in winter. Spring trends marked the 1920s warming onset, while

  13. Complexation of Lanthanides with Nitrate at Variable Temperatures: Thermodynamics and Coordination Modes

    SciTech Connect

    Rao, Linfeng; Tian, Guoxin

    2008-12-10

    Complexation of neodymium(III) with nitrate was studied at variable temperatures (25, 40, 55 and 70 C) by spectrophotometry and microcalorimetry. The NdNO{sub 3}{sup 2+} complex is weak and becomes slightly stronger as the temperature is increased. The enthalpy of complexation at 25 C was determined by microcalorimetry to be small and positive, (1.5 {+-} 0.2) kJ {center_dot} mol{sup -1}, in good agreement with the trend of the stability constant at variable temperatures. Luminescence emission spectra and lifetime of Eu(III) in nitrate solutions suggest that inner-sphere and bidentate complexes form between trivalent lanthanides (Nd{sup 3+} and Eu{sup 3+}) and nitrate in aqueous solutions. Specific Ion Interaction approach (SIT) was used to obtain the stability constants of NdNO{sub 3}{sup 2+} at infinite dilution and variable temperatures.

  14. The optimization of variable cross-section spines with temperature dependent thermal parameters

    NASA Astrophysics Data System (ADS)

    Reardon, J.; Razani, A.

    1992-08-01

    An optimization method based on a temperature correlated profile is expanded upon for the optimization of pin fins with variable cross-sections including the temperature dependence of thermal parameters. The application of this method to optimization of fin arrays is discussed. The validity of the optimization method for a single fin is demonstrated by comparison to analytical results of a special case. An example demonstrates the importance of considering temperature dependence of thermal parameters when optimizing a heat sink.

  15. A variable-temperature nanostencil compatible with a low-temperature scanning tunneling microscope/atomic force microscope

    SciTech Connect

    Steurer, Wolfram, E-mail: wst@zurich.ibm.com; Gross, Leo; Schlittler, Reto R.; Meyer, Gerhard [IBM Research-Zurich, 8803 Rüschlikon (Switzerland)] [IBM Research-Zurich, 8803 Rüschlikon (Switzerland)

    2014-02-15

    We describe a nanostencil lithography tool capable of operating at variable temperatures down to 30 K. The setup is compatible with a combined low-temperature scanning tunneling microscope/atomic force microscope located within the same ultra-high-vacuum apparatus. The lateral movement capability of the mask allows the patterning of complex structures. To demonstrate operational functionality of the tool and estimate temperature drift and blurring, we fabricated LiF and NaCl nanostructures on Cu(111) at 77 K.

  16. Hydrogeologic controls on baseflow temperature distributions: Implications for stream temperature response to climate variability

    NASA Astrophysics Data System (ADS)

    Boutt, D. F.; Smith, Z.

    2012-12-01

    Ground water temperature distributions in the near surface are not uniform and are the complex result of a variety of near- and sub-surface processes. Heat from the atmosphere is input into the ground via conduction at the ground surface and advection of infiltrating water. These processes produce predictable distributions of temperature that have been used to investigate current and past climatic conditions, determine ground water velocities, and assess basin-scale heat transport in sedimentary systems. The purpose of this investigation is to test a hypothesis that timing and nature of ground water recharge (advection of heat into the subsurface) is a significant control on the temporal and spatial distribution of heat in the shallow subsurface. The advective movement of heat imposes a dominant control on the 3-dimensional subsurface temperature distribution and strongly affects stream baseflow temperatures. We present observational data supporting a strong hydrogeologic control on subsurface water temperatures. These temperature distributions are modified by advection and are significantly different than theoretical distributions in a conduction-dominated environment. The temperature distributions with depth and space are controlled by the aquifers internal hydrogeologic structure and connections to recharge areas. Synthetic modeling is used to address the following questions: (1) how quickly do ground water temperatures respond to a changing climate, and how quickly do they reach a new equilibrium following perturbation; (2) what is the role of recharge water temperature and timing on subsurface temperature distributions; and (3) how do these factors influence baseflow temperatures in stream systems of varying size. Two-dimensional numerical models are developed using Comsol Multiphysics to perform a sensitivity analysis of basin-scale temperature response and coupling to surface water. In nested ground water flow systems, discharge areas farther down the regional hydraulic gradient receive groundwater from increasingly longer flow paths. As such, temperatures in upper portions of the flow system respond sooner to temperature changes than those in lower portions of the system. The upper portions of the model achieved equilibrium with temperature forcing within a few years, while downstream portions required more than 10 years to achieve equilibrium. The results reiterate the importance of advection-driven heat flow to the thermal response of shallow ground water systems and nested basins. Seasonal temperature signatures penetrate deeper and farther down the regional gradient in highly advective systems versus moderately advective systems. Models illustrate the persistence of the seasonal increased heat signature in the subsurface and propagation of that signature with the regional gradient. Upstream discharge locations respond quickly to increased temperatures and receive higher temperature baseflow than under the baseline conditions. Downstream discharge locations are somewhat buffered from increased temperatures due to longer flow paths.

  17. Temperature variability and moisture synergistically interact to exacerbate an epizootic disease.

    PubMed

    Raffel, Thomas R; Halstead, Neal T; McMahon, Taegan A; Davis, Andrew K; Rohr, Jason R

    2015-02-22

    Climate change is altering global patterns of precipitation and temperature variability, with implications for parasitic diseases of humans and wildlife. A recent study confirmed predictions that increased temperature variability could exacerbate disease, because of lags in host acclimation following temperature shifts. However, the generality of these host acclimation effects and the potential for them to interact with other factors have yet to be tested. Here, we report similar effects of host thermal acclimation (constant versus shifted temperatures) on chytridiomycosis in red-spotted newts (Notophthalmus viridescens). Batrachochytrium dendrobatidis (Bd) growth on newts was greater following a shift to a new temperature, relative to newts already acclimated to this temperature (15°C versus 25°C). However, these acclimation effects depended on soil moisture (10, 16 and 21% water) and were only observed at the highest moisture level, which induced greatly increased Bd growth and infection-induced mortality. Acclimation effects were also greater following a decrease rather than an increase in temperature. The results are consistent with previous findings that chytridiomycosis is associated with precipitation, lower temperatures and increased temperature variability. This study highlights host acclimation as a potentially general mediator of climate-disease interactions, and the need to account for context-dependencies when testing for acclimation effects on disease. PMID:25567647

  18. Ocean surface temperature variability: large model-data differences at decadal and longer periods.

    PubMed

    Laepple, Thomas; Huybers, Peter

    2014-11-25

    The variability of sea surface temperatures (SSTs) at multidecadal and longer timescales is poorly constrained, primarily because instrumental records are short and proxy records are noisy. Through applying a new noise filtering technique to a global network of late Holocene SST proxies, we estimate SST variability between annual and millennial timescales. Filtered estimates of SST variability obtained from coral, foraminifer, and alkenone records are shown to be consistent with one another and with instrumental records in the frequency bands at which they overlap. General circulation models, however, simulate SST variability that is systematically smaller than instrumental and proxy-based estimates. Discrepancies in variability are largest at low latitudes and increase with timescale, reaching two orders of magnitude for tropical variability at millennial timescales. This result implies major deficiencies in observational estimates or model simulations, or both, and has implications for the attribution of past variations and prediction of future change. PMID:25385623

  19. Variability patterns of the general circulation and sea water temperature in the North Sea

    NASA Astrophysics Data System (ADS)

    Mathis, M.; Elizalde, A.; Mikolajewicz, U.; Pohlmann, T.

    2015-06-01

    This study investigates patterns of spatio-temporal variability in the North Sea and their major driving mechanisms. Leading variability modes of the general circulation and sea water temperature are extracted from model results by means of Empirical Orthogonal Functions (EOF) analysis. The model results originate from an uncoupled simulation with the global ocean model MPIOM, forced with ERA40 reanalysis data at the air-sea interface. For this regional model study, MPIOM has been run with a stretched grid configuration enabling higher horizontal resolution in the Northwest European Shelf and North Atlantic ocean. The analysis is applied to interannual variabilities of winter and summer separately. The results indicate that on seasonal scales the leading variability mode of the general circulation affects the entire North Sea, accompanied by significant inflow anomalies through the Fair-Isle Passage. Correlations of the corresponding Principal Component (PC) with wind density functions reveal the circulation anomalies to coincide with westerly and south-westerly wind anomalies. The second mode describes circulation anomalies along the Norwegian Trench and English Channel, which correlate with north-westerly wind anomalies caused by variations in large-scale atmospheric pressure areas centered over the British Isles. For sea water temperature, distinct variability patterns are induced by variable surface heat fluxes, vertical mixing, and variable advective heat fluxes. The first mode of both the general circulation and water temperature in winter mainly represents the response to atmospheric variations in the North Atlantic Oscillation (NAO). However, the higher modes account for such variabilities that cannot be explained by the NAO. As a consequence of the integrated effects of the different variability modes on the circulation system and heat content, local correlations of the NAO with volume transports and water temperature are weakened in the regions of Atlantic inflow.

  20. Effects of outdoor temperature on changes in physiological variables before and after lunch in healthy women

    NASA Astrophysics Data System (ADS)

    Okada, Masahiro; Kakehashi, Masayuki

    2014-03-01

    Previous studies of autonomic nervous system responses before and after eating when controlling patient conditions and room temperature have provided inconsistent results. We hypothesized that several physiological parameters reflecting autonomic activity are affected by outdoor temperature before and after a meal. We measured the following physiological variables before and after a fixed meal in 53 healthy Japanese women: skin temperature, systolic and diastolic blood pressure, salivary amylase, blood glucose, heart rate, and heart rate variability. We assessed satiety before and after lunch using a visual analog scale (100 mm). We recorded outdoor temperature, atmospheric pressure, and relative humidity. Skin temperature rose significantly 1 h after eating (greater in cold weather) (P = 0.008). Cold weather markedly influenced changes in diastolic blood pressure before (P = 0.017) and after lunch (P = 0.013). Fasting salivary amylase activity increased significantly in cold weather but fell significantly after lunch (significantly greater in cold weather) (P = 0.007). Salivary amylase was significantly associated with cold weather, low atmospheric pressure, and low relative humidity 30 min after lunch (P < 0.05). Cold weather significantly influenced heart rate variability (P = 0.001). The decreased low frequency (LF)/high frequency (HF) ratio, increased ? LF/HF ratio, and increased ? salivary amylase activity imply that cold outdoor temperature is associated with dominant parasympathetic activity after lunch. Our results clarify the relationship between environmental factors, food intake, and autonomic system and physiological variables, which helps our understanding of homeostasis and metabolism.

  1. Linkages Between Multiscale Global Sea Surface Temperature Change and Precipitation Variabilities in the US

    NASA Technical Reports Server (NTRS)

    Lau, K. M.; Weng, Heng-Yi

    1999-01-01

    A growing number of evidence indicates that there are coherent patterns of variability in sea surface temperature (SST) anomaly not only at interannual timescales, but also at decadal-to-inter-decadal timescale and beyond. The multi-scale variabilities of SST anomaly have shown great impacts on climate. In this work, we analyze multiple timescales contained in the globally averaged SST anomaly with and their possible relationship with the summer and winter rainfall in the United States over the past four decades.

  2. Associations of decadal to multidecadal sea-surface temperature variability with Upper Colorado River flow

    USGS Publications Warehouse

    McCabe, G.J.; Betancourt, J.L.; Hidalgo, H.G.

    2007-01-01

    The relations of decadal to multidecadal (D2M) variability in global sea-surface temperatures (SSTs) with D2M variability in the flow of the Upper Colorado River Basin (UCRB) are examined for the years 1906-2003. Results indicate that D2M variability of SSTs in the North Atlantic, North Pacific, tropical Pacific, and Indian Oceans is associated with D2M variability of the UCRB. A principal components analysis (with varimax rotation) of detrended and 11-year smoothed global SSTs indicates that the two leading rotated principal components (RPCs) explain 56% of the variability in the transformed SST data. The first RPC (RPC1) strongly reflects variability associated with the Atlantic Multidecadal Oscillation and the second RPC (RPC2) represents variability of the Pacific Decadal Oscillation, the tropical Pacific Ocean, and Indian Ocean SSTs. Results indicate that SSTs in the North Atlantic Ocean (RPC1) explain as much of the D2M variability in global SSTs as does the combination of Indian and Pacific Ocean variability (RPC2). These results suggest that SSTs in all of the oceans have some relation with flow of the UCRB, but the North Atlantic may have the strongest and most consistent association on D2M time scales. Hydroclimatic persistence on these time scales introduces significant nonstationarity in mean annual streamflow, with critical implications for UCRB water resource management. ?? 2007 American Water Resources Association.

  3. Six hundred thirty-eight years of summer temperature variability over the Bhutanese Himalaya

    NASA Astrophysics Data System (ADS)

    Krusic, P. J.; Cook, E. R.; Dukpa, D.; Putnam, A. E.; Rupper, S.; Schaefer, J.

    2015-04-01

    High-resolution tree ring reconstructions from the Himalaya provide essential context for assessing impacts of future climate change on regional water reserves and downstream agriculture. Here we evaluate a small network of tree ring chronologies from Bhutan to produce a 638 year summer temperature reconstruction, from 1376-2013 (Common Era) C.E. Relative to the 1950-2013 C.E. average summer temperature three prominent cold periods stand out, two in the midfifteenth century, and one in the late seventeenth century. The warmest period began in the first decade of the 21st century coinciding with the timing of general glacier recession in the eastern Himalaya that continues to the present. The Bhutan temperature reconstruction exhibits a significant correlation to known volcanic eruptions (p = 97%) and anomalously cold periods appear to align with solar irradiance minima in the fifteenth, late seventeenth, and early nineteenth centuries, implying a link between solar variability and decadal-scale temperature variability.

  4. Interannual variability in upper ocean heat content, temperature, and thermosteric expansion on global scales

    Microsoft Academic Search

    Josh K. Willis; Dean Roemmich; Bruce Cornuelle

    2004-01-01

    Satellite altimetric height was combined with approximately 1,000,000 in situ temperature profiles to produce global estimates of upper ocean heat content, temperature, and thermosteric sea level variability on interannual timescales. Maps of these quantities from mid-1993 through mid-2003 were calculated using the technique developed by Willis et al. [2003]. The time series of globally averaged heat content contains a small

  5. Interannual variability of wintertime temperature on the inner continental shelf of the Middle Atlantic Bight

    NASA Astrophysics Data System (ADS)

    Connolly, Thomas P.; Lentz, Steven J.

    2014-09-01

    The shallow depth of the inner continental shelf allows for rapid adjustment of the ocean to air-sea exchange of heat and momentum compared with offshore locations. Observations during 2001-2013 are used to evaluate the contributions of air-sea heat flux and oceanic advection to interannual variability of inner-shelf temperature in the Middle Atlantic Bight. Wintertime processes are important for interpreting regional interannual variability at nearshore locations since winter anomalies account for 69-77% of the variance of the annual anomalies and are correlated over broad along-shelf scales, from New England to North Carolina. At the Martha's Vineyard Coastal Observatory on the 12 m isobath, a heat budget is used to test the hypothesis that interannual differences in winter temperatures are due solely to air-sea heat flux. Bimonthly averages of air-sea heat flux are correlated with temporal changes in temperature, but overestimate the observed wintertime cooling. Velocity and satellite-derived temperature data show that interannual variability in wintertime surface cooling is partially compensated for by alongshore advection of warmer water from the west at this particular location. It is also shown that surface heat flux is a strong function of air-sea temperature difference. Because of this coupling between ocean and air temperatures in shallow water, along-shelf advection can significantly modify the surface heat flux at seasonal and interannual time scales. While along-shelf advection at relatively small (˜100 km) scales can be an important component of the heat budget over the inner shelf, interannual temperature variability is still largely determined by adjustment to large-scale air-temperature anomalies.

  6. Influence of the Arctic Oscillation on the variability of winter mean temperatures in Turkey

    Microsoft Academic Search

    M. Türkes; E. Erlat

    2008-01-01

    Summary  Observed changes and variability in winter (DJF) mean temperature series at the 70 stations of Turkey and the circulation\\u000a types at 500-hPa geopotential height level were investigated to explain atmospheric controls of the temperature variations\\u000a during the extreme and normal phases of the Arctic Oscillation Index (AOI). The analysis was performed with respect to relationships\\u000a between winter (monthly and seasonal)

  7. Investigation on multi-variable decoupled temperature control system for enamelling machine with heated air circulation

    SciTech Connect

    Li, Yang; Qin, Le; Zou, Shipeng; Long, Shijun [School of Information Engineering, Guangdong University of Technology, Guangzhou, 510006 (China)

    2014-04-11

    A lots of problems may occur frequently when controlling the temperature of the enamelling machine oven in the real industrial process, such as multi-variable coupled problem. an experimental rig with triple inputs and triple outputs was devised and a simulation modeling was established accordingly in this study,. the temperature control system based on the feedforward compensation algorithm was proposed. Experimental results have shown that the system is of high efficiency, good stability and promising application.

  8. Separating the influence of temperature, drought, and fire on interannual variability in atmospheric CO2

    NASA Astrophysics Data System (ADS)

    Keppel-Aleks, Gretchen; Wolf, Aaron S.; Mu, Mingquan; Doney, Scott C.; Morton, Douglas C.; Kasibhatla, Prasad S.; Miller, John B.; Dlugokencky, Edward J.; Randerson, James T.

    2014-11-01

    The response of the carbon cycle in prognostic Earth system models (ESMs) contributes significant uncertainty to projections of global climate change. Quantifying contributions of known drivers of interannual variability in the growth rate of atmospheric carbon dioxide (CO2) is important for improving the representation of terrestrial ecosystem processes in these ESMs. Several recent studies have identified the temperature dependence of tropical net ecosystem exchange (NEE) as a primary driver of this variability by analyzing a single, globally averaged time series of CO2 anomalies. Here we examined how the temporal evolution of CO2 in different latitude bands may be used to separate contributions from temperature stress, drought stress, and fire emissions to CO2 variability. We developed atmospheric CO2 patterns from each of these mechanisms during 1997-2011 using an atmospheric transport model. NEE responses to temperature, NEE responses to drought, and fire emissions all contributed significantly to CO2 variability in each latitude band, suggesting that no single mechanism was the dominant driver. We found that the sum of drought and fire contributions to CO2 variability exceeded direct NEE responses to temperature in both the Northern and Southern Hemispheres. Additional sensitivity tests revealed that these contributions are masked by temporal and spatial smoothing of CO2 observations. Accounting for fires, the sensitivity of tropical NEE to temperature stress decreased by 25% to 2.9 ± 0.4 Pg C yr-1 K-1. These results underscore the need for accurate attribution of the drivers of CO2 variability prior to using contemporary observations to constrain long-term ESM responses.

  9. Separating the influence of temperature, drought, and fire on interannual variability in atmospheric CO2

    PubMed Central

    Keppel-Aleks, Gretchen; Wolf, Aaron S; Mu, Mingquan; Doney, Scott C; Morton, Douglas C; Kasibhatla, Prasad S; Miller, John B; Dlugokencky, Edward J; Randerson, James T

    2014-01-01

    The response of the carbon cycle in prognostic Earth system models (ESMs) contributes significant uncertainty to projections of global climate change. Quantifying contributions of known drivers of interannual variability in the growth rate of atmospheric carbon dioxide (CO2) is important for improving the representation of terrestrial ecosystem processes in these ESMs. Several recent studies have identified the temperature dependence of tropical net ecosystem exchange (NEE) as a primary driver of this variability by analyzing a single, globally averaged time series of CO2 anomalies. Here we examined how the temporal evolution of CO2 in different latitude bands may be used to separate contributions from temperature stress, drought stress, and fire emissions to CO2 variability. We developed atmospheric CO2 patterns from each of these mechanisms during 1997–2011 using an atmospheric transport model. NEE responses to temperature, NEE responses to drought, and fire emissions all contributed significantly to CO2 variability in each latitude band, suggesting that no single mechanism was the dominant driver. We found that the sum of drought and fire contributions to CO2 variability exceeded direct NEE responses to temperature in both the Northern and Southern Hemispheres. Additional sensitivity tests revealed that these contributions are masked by temporal and spatial smoothing of CO2 observations. Accounting for fires, the sensitivity of tropical NEE to temperature stress decreased by 25% to 2.9?±?0.4 Pg C yr?1?K?1. These results underscore the need for accurate attribution of the drivers of CO2 variability prior to using contemporary observations to constrain long-term ESM responses.

  10. Decadal Variability of the Tropical Atlantic Ocean Surface Temperature in Shipboard Measurements and in a Global Ocean-Atmosphere Model

    Microsoft Academic Search

    Vikram M. Mehta; Thomas Delworth

    1995-01-01

    Numerous analyses of relatively short (25-30 years in length) time series of the observed surface temperature of the tropical Atlantic Ocean have indicated the possible existence of decadal timescale variability. It was decided to search for such variability in 100-yr time series of sea surface temperature (SST) measured aboard ships and available in the recently published Global Ocean Surface Temperature

  11. Effects of precipitation and temperature on crop production variability in northeast Iran.

    PubMed

    Bannayan, Mohammad; Lotfabadi, Sajad Sadeghi; Sanjani, Sarah; Mohamadian, Azadeh; Aghaalikhani, Majid

    2011-05-01

    Climate variability adversely impacts crop production and imposes a major constraint on farming planning, mostly under rainfed conditions, across the world. Considering the recent advances in climate science, many studies are trying to provide a reliable basis for climate, and subsequently agricultural production, forecasts. The El Niño-Southern Oscillation phenomenon (ENSO) is one of the principle sources of interannual climatic variability. In Iran, primarily in the northeast, rainfed cereal yield shows a high annual variability. This study investigated the role played by precipitation, temperature and three climate indices [Arctic Oscillation (AO), North Atlantic Oscillation (NAO) and NINO 3.4] in historically observed rainfed crop yields (1983-2005) of both barley and wheat in the northeast of Iran. The results revealed differences in the association between crop yield and climatic factors at different locations. The south of the study area is a very hot location, and the maximum temperature proved to be the limiting and determining factor for crop yields; temperature variability resulted in crop yield variability. For the north of the study area, NINO 3.4 exhibited a clear association trend with crop yields. In central locations, NAO provided a solid basis for the relationship between crop yields and climate factors. PMID:20706741

  12. The relationship of rainfall variability in West Central Africa to sea-surface temperature fluctuations

    Microsoft Academic Search

    N. Balas; S. E. Nicholson; D. Klotter

    2007-01-01

    This study examines the interannual variability of rainfall in western equatorial Africa and its links to sea-surface temperatures (SSTs). Five geographical regions within the latitudes 10 °N-5 °S are delineated for the analysis. The links to SSTs in the tropical Atlantic, Pacific and Indian Oceans are examined via seasonal composites of wet and dry years and via linear correlations. The

  13. Variable-Temperature Electrical Measurements of Zinc Oxide/Tin Oxide-Cosubstituted Indium Oxide

    E-print Network

    Poeppelmeier, Kenneth R.

    Variable-Temperature Electrical Measurements of Zinc Oxide/Tin Oxide-Cosubstituted Indium Oxide A-), undoped In2O3, and indium-tin oxide (ITO) were studied vs cation composition, state of reduction of choice, tin-doped indium oxide (ITO) has a typical conductivity of 1-5 × 103 S/cm and a transpar- ency

  14. High variability of Greenland surface temperature over the past 4000 years estimated from trapped air

    E-print Network

    Severinghaus, Jeffrey P.

    High variability of Greenland surface temperature over the past 4000 years estimated from trapped 10 October 2011; accepted 11 October 2011; published 10 November 2011. [1] Greenland recently is impacting the Greenland ice sheet and in turn accelerating global sealevel rise. Yet, it remains imprecisely

  15. Impact of interannual rainfall anomalies on Indian Ocean salinity and temperature variability

    Microsoft Academic Search

    Claire Perigaud; Julian P. McCreary; Kate Q. Zhang

    2003-01-01

    A nonlinear reduced gravity model with four active layers and mixed layer physics is used to investigate how precipitation anomalies affect salinity and temperature variability in the Indian Ocean. In one experiment the model is forced by observations of monthly varying winds and rainfall for the period 1980-2000. In another it is forced by the same winds and climatological rainfall.

  16. Impact of interannual rainfall anomalies on Indian Ocean salinity and temperature variability

    Microsoft Academic Search

    Claire Perigaud; Julian P. McCreary Jr; Kate Q. Zhang

    2003-01-01

    A nonlinear reduced gravity model with four active layers and mixed layer physics is used to investigate how precipitation anomalies affect salinity and temperature variability in the Indian Ocean. In one experiment the model is forced by observations of monthly varying winds and rainfall for the period 1980–2000. In another it is forced by the same winds and climatological rainfall.

  17. Carbonate clumped isotope variability in shallow water corals: Temperature dependence and growth-related vital effects

    E-print Network

    Carbonate clumped isotope variability in shallow water corals: Temperature dependence and growth September 2012; available online 28 September 2012 Abstract Geochemical variations in shallow water corals in the winter growth of a hermatypic coral provided early evidence for possible D47 vital effects. Here, we

  18. Florida Current surface temperature and salinity variability during the last millennium

    Microsoft Academic Search

    David C. Lund; William Curry

    2006-01-01

    The salinity and temperature of the Florida Current are key parameters affecting the transport of heat into the North Atlantic, yet little is known about their variability on centennial timescales. Here we report replicated, high-resolution foraminiferal records of Florida Current surface hydrography for the last millennium from two coring sites, Dry Tortugas and the Great Bahama Bank. The oxygen isotopic

  19. Temporal and spatial variabilities of the South China Sea surface temperature anomaly

    Microsoft Academic Search

    Peter C. Chu; Shihua Lu; Yuchun Chen

    1997-01-01

    In this study we use the National Centers for Environmental Prediction (NCEP) monthly sea surface temperature (SST) fields (1982-1994) to investigate the temporal and spatial variabilities of the South China Sea (SCS) warm\\/cool anomalies. Three steps of analysis were performed on the data set: ensemble mean (T), composite analysis to obtain the monthly mean anomaly relative to the ensemble mean

  20. Temporal variability of remotely sensed suspended sediment and sea surface temperature patterns in Mobile Bay, Alabama

    USGS Publications Warehouse

    Rucker, J.B.; Stumpf, R.P.; Schroeder, W.W.

    1990-01-01

    Distribution patterns of suspended sediments and sea surface temperatures in, Mobile Bay were derived from algorithms using digital data from the visible, near infrared, and infrared channels of the Advanced Very High Resolution Radiometer (AVHRR) on the NOAA-TIROS-N satellite. Closely spaced AVHRR scenes for January 20, 24, and 29, 1982, were compared with available environmental information taken during the same period. A complex interaction between river discharge, winds, and astronomical tides controlled the distribution patterns of suspended sediments. These same variables, coupled with air temperatures, also governed the distribution patterns of sea surface temperatures. ?? 1990 Estuarine Research Federation.

  1. Recent temperature variability and trends in the coastal areas of the western Svalbard

    NASA Astrophysics Data System (ADS)

    Isaksen, Ketil; Nordli, Øyvind; Przybylak, Rajmund; Wyszynski, Przemyslaw

    2015-04-01

    The Svalbard Archipelago (74°-81°N, 10°-35°E) has experienced the greatest temperature increase in Europe during the latest three decades. Svalbard is also noted for its wide year-to-year variation in monthly temperatures and weather. The project "Arctic climate system study of ocean, sea ice and glaciers interactions in Svalbard area" (AWAKE-2) is a continuation and extension of the Polish-Norwegian AWAKE project (2009-2011). The aim of the AWAKE-2 is to understand the interactions between the main components of the climate system in the Svalbard area to identify mechanisms of interannual climate variability and long-term trends. The main hypothesis is that the Atlantic Water inflows over the Svalbard shelf and into the fjords have become more frequent during the last decades due to changes in the ocean and atmosphere. The integrated effect of these events results in new regimes and changes in atmosphere, ocean, sea ice and glaciers in Svalbard. Furthermore, changes in the cryosphere create feedback effects in ocean and atmosphere. One of the objectives in the AWAKE-2 project is to study atmospheric climate variability and trends in the coastal areas of the western Svalbard. In this study we analyse the recent temperature increase and temperature variability along the western coastal areas of Svalbard and compare this to the long-term variability based on historical data. Especially focus is given to the spatial and temporal air temperature gradients along western Svalbard. Changes in possible key factors controlling the recent large temperature anomalies are discussed.

  2. Medieval Warm Period, Little Ice Age and 20th century temperature variability from Chesapeake Bay

    USGS Publications Warehouse

    Cronin, T. M.; Dwyer, G.S.; Kamiya, T.; Schwede, S.; Willard, D.A.

    2003-01-01

    We present paleoclimate evidence for rapid (< 100 years) shifts of ??? 2-4??C in Chesapeake Bay (CB) temperature ???2100, 1600, 950, 650, 400 and 150 years before present (years BP) reconstructed from magnesium/calcium (Mg/Ca) paleothermometry. These include large temperature excursions during the Little Ice Age (???1400-1900 AD) and the Medieval Warm Period (???800-1300 AD) possibly related to changes in the strength of North Atlantic thermohaline circulation (THC). Evidence is presented for a long period of sustained regional and North Atlantic-wide warmth with low-amplitude temperature variability between ???450 and 1000 AD. In addition to centennial-scale temperature shifts, the existence of numerous temperature maxima between 2200 and 250 years BP (average ???70 years) suggests that multi-decadal processes typical of the North Atlantic Oscillation (NAO) are an inherent feature of late Holocene climate. However, late 19th and 20th century temperature extremes in Chesapeake Bay associated with NAO climate variability exceeded those of the prior 2000 years, including the interval 450-1000 AD, by 2-3??C, suggesting anomalous recent behavior of the climate system. ?? 2002 Elsevier Science B.V. All rights reserved.

  3. Variation among Species in the Temperature Dependence of the Reappearance of Variable Fluorescence following Illumination.

    PubMed

    Burke, J J

    1990-06-01

    The relationship between the thermal dependence of the reappearance of chlorophyll variable fluorescence following illumination and temperature dependence of the apparent Michaelis constant (K(m)) of NADH hydroxypyruvate reductase for NADH was investigated in cool and warm season plant species. Brancker SF-20 and SF-30 fluorometers were used to evaluate induced fluorescence transients from detached leaves of wheat (Triticum aestivum L. cv TAM-101), cotton (Gossypium hirsutum L. cv Paymaster 145), tomato (Lycopersicon esculentum cv Del Oro), bell pepper (Capsicum annuum L. cv California Wonder), and petunia (Petunia hybrida cv. Red Sail). Following an illumination period at 25 degrees C, the reappearance of variable fluorescence during a dark incubation was determined at 5 degrees C intervals from 15 degrees C to 45 degrees C. Variable fluorescence recovery was normally distributed with the maximum recovery observed at 20 degrees C in wheat, 30 degrees C in cotton, 20 degrees C to 25 degrees C in tomato, 30 to 35 degrees C in bell pepper and 25 degrees C in petunia. Comparison of the thermal response of fluorescence recovery with the temperature sensitivity of the apparent K(m) of hydroxypyruvate reductase for NADH showed that the range of temperatures providing fluorescence recovery corresponded with those temperatures providing the minimum apparent K(m) values (viz. the thermal kinetic window). PMID:16667518

  4. Variation among Species in the Temperature Dependence of the Reappearance of Variable Fluorescence following Illumination

    PubMed Central

    Burke, John J.

    1990-01-01

    The relationship between the thermal dependence of the reappearance of chlorophyll variable fluorescence following illumination and temperature dependence of the apparent Michaelis constant (Km) of NADH hydroxypyruvate reductase for NADH was investigated in cool and warm season plant species. Brancker SF-20 and SF-30 fluorometers were used to evaluate induced fluorescence transients from detached leaves of wheat (Triticum aestivum L. cv TAM-101), cotton (Gossypium hirsutum L. cv Paymaster 145), tomato (Lycopersicon esculentum cv Del Oro), bell pepper (Capsicum annuum L. cv California Wonder), and petunia (Petunia hybrida cv. Red Sail). Following an illumination period at 25°C, the reappearance of variable fluorescence during a dark incubation was determined at 5°C intervals from 15°C to 45°C. Variable fluorescence recovery was normally distributed with the maximum recovery observed at 20°C in wheat, 30°C in cotton, 20°C to 25°C in tomato, 30 to 35°C in bell pepper and 25°C in petunia. Comparison of the thermal response of fluorescence recovery with the temperature sensitivity of the apparent Km of hydroxypyruvate reductase for NADH showed that the range of temperatures providing fluorescence recovery corresponded with those temperatures providing the minimum apparent Km values (viz. the thermal kinetic window). PMID:16667518

  5. Decreased skin temperature of the foot increases gait variability in healthy young adults.

    PubMed

    Sawa, Ryuichi; Doi, Takehiko; Misu, Shogo; Tsutsumimoto, Kota; Fujino, Hidemi; Ono, Rei

    2013-07-01

    We investigated the effects of reduction in plantar skin temperature on gait. Thirty-four healthy subjects (20 men and 14 women; mean age 22.2±2.5 years; mean height 166.8±8.3cm) walked 16m under two different conditions - normal conditions (NC) with the skin at a basal temperature, and cold conditions (CC) after cooling of the plantar skin to about 15°C. Wireless motion-recording sensor units were placed on the back at the level of L3 and on both heels to measure acceleration and angular velocity. Gait velocity and mean stride, stance and swing times were calculated. The variability of lower limb movement was represented by the coefficients of variation (CVs) of stride, stance and swing times, and that of trunk movement was represented by autocorrelation coefficients (ACs) in three directions (vertical: VT; mediolateral: ML; and anteroposterior: AP). Gait velocity was significantly lower under CC conditions than under NC (p<0.0001). None of the temporal parameters were changed by plantar cooling. However, all parameters of gait variability were significantly worse under CC, and AC-VT, AC-ML, and AC-AP were significantly lower under CC than under NC, even after adjusting for gait velocity (p=0.0005, 0.0071, and 0.0126, respectively). Our results suggest that reducing plantar skin temperature induces gait variability among healthy young adults. Further studies are now needed to explore the relationship between plantar skin temperature and gait in the elderly. PMID:23465760

  6. Impact of the Dominant Large-scale Teleconnections on Winter Temperature Variability over East Asia

    NASA Technical Reports Server (NTRS)

    Lim, Young-Kwon; Kim, Hae-Dong

    2013-01-01

    Monthly mean geopotential height for the past 33 DJF seasons archived in Modern Era Retrospective analysis for Research and Applications reanalysis is decomposed into the large-scale teleconnection patterns to explain their impacts on winter temperature variability over East Asia. Following Arctic Oscillation (AO) that explains the largest variance, East Atlantic/West Russia (EA/WR), West Pacific (WP) and El Nino-Southern Oscillation (ENSO) are identified as the first four leading modes that significantly explain East Asian winter temperature variation. While the northern part of East Asia north of 50N is prevailed by AO and EA/WR impacts, temperature in the midlatitudes (30N-50N), which include Mongolia, northeastern China, Shandong area, Korea, and Japan, is influenced by combined effect of the four leading teleconnections. ENSO impact on average over 33 winters is relatively weaker than the impact of the other three teleconnections. WP impact, which has received less attention than ENSO in earlier studies, characterizes winter temperatures over Korea, Japan, and central to southern China region south of 30N mainly by advective process from the Pacific. Upper level wave activity fluxes reveal that, for the AO case, the height and circulation anomalies affecting midlatitude East Asian winter temperature is mainly located at higher latitudes north of East Asia. Distribution of the fluxes also explains that the stationary wave train associated with EA/WR propagates southeastward from the western Russia, affecting the East Asian winter temperature. Investigation on the impact of each teleconnection for the selected years reveals that the most dominant teleconnection over East Asia is not the same at all years, indicating a great deal of interannual variability. Comparison in temperature anomaly distributions between observation and temperature anomaly constructed using the combined effect of four leading teleconnections clearly show a reasonable consistency between them, demonstrating that the seasonal winter temperature distributions over East Asia are substantially explained by these four large-scale circulation impacts.

  7. Identification of mid-latitudinal regional and urban temperature variabilities based on regional reanalysis data

    NASA Astrophysics Data System (ADS)

    Choi, Woonsup; Keuser, Anke; Becker, Stefan

    2012-01-01

    The objective of the study is to detect geographical and temporal variations of near surface air temperatures over Minnesota and Wisconsin, USA derived from the North American Regional Reanalysis (NARR) dataset. In addition, the study serves to assess the usefulness of NARR temperature data to analyze regional and local temperature variations. Particular emphasis was placed on the analyses on the temperature-modifying effects of the Great Lakes and large urban environments. We analyzed annual mean, daily maximum and minimum, and January minimum and July maximum temperatures for the period 1979-2006 by using methods such as ordinary kriging, principal component analysis, and the Mann-Kendall test. On a regional scale, we found significant effects of the latitude and the Great Lakes on the spatial variability of the data. Furthermore, we found clearly identifiable effects of large urban areas in the study region (Minneapolis—Saint Paul and Milwaukee), which are more evident in the principal component scores than in the temperature data themselves. While we failed to detect significant July maximum temperature trends, we detected significantly increasing trends in January minimum and mean annual temperature datasets in the eastern part of the region. Overall, the present study has demonstrated the potential of using NARR data for urban climate research.

  8. A variable temperature cryostat that produces in situ clean-up germanium detector surfaces

    NASA Astrophysics Data System (ADS)

    Pehl, R. H.; Madden, N. W.; Malone, D. F.; Cork, C. P.; Landis, D. A.; Xing, J. S.; Friesel, D. L.

    1988-11-01

    Variable temperature cryostats that can maintain germanium detectors at temperatures from 82 K to about 400 K while the thermal shield surrounding the detectors remains much colder when the detectors are warmed have been developed. Cryostats such as these offer the possibility of cryopumping material from the surface of detectors to the colder thermal shield. The diode characteristics of several detectors have shown very significant improvement following thermal cycles up to about 150 K in these cryostats. Important applications for cryostats having this attribute are many.

  9. Spatial variability of surface temperature as related to cropping practice with implications for irrigation management

    NASA Technical Reports Server (NTRS)

    Hatfield, J. L.; Millard, J. P.; Reginato, R. J.; Jackson, R. D.; Idso, S. B.; Pinter, P. J., Jr.; Goettelman, R. C.

    1980-01-01

    Crop stress measured using thermal infrared emission is evaluated with the stress-degree-day (SDD) concept. Throughout the season, the accumulation of SDD during the reproductive stage of growth is inversely related to yield. This relationship is shown for durum wheat, hard red winter wheat, barley, grain sorghum and soybeans. It is noted that SDD can be used to schedule irrigations for maximizing yields and for applying remotely sensed data to management of water resources. An airborne flight with a thermal-IR scanner was used to examine the variability in temperature that may exist from one field to another and to determine realistic within-field temperature variations. It was found that the airborne and the ground-based data agreed very well and that there was less variability in the fields that were completely covered with crops than those of bare soil.

  10. Climate reconstructions of the NH mean temperature: Can underestimation of trends and variability be avoided?

    NASA Astrophysics Data System (ADS)

    Christiansen, Bo

    2010-05-01

    Knowledge about the climate in the period before instrumental records are available is based on climate proxies obtained from tree-rings, sediments, ice-cores etc. Reconstructing the climate from such proxies is therefore necessary for studies of climate variability and for placing recent climate change into a longer term perspective. More than a decade ago pioneering attempts at using a multi-proxy dataset to reconstruct the Northern Hemisphere (NH) mean temperature resulted in the much published "hockey-stick"; a NH mean temperature that did not vary much before the rapid increase in the last century. Subsequent reconstructions show some differences but the overall "hockey-stick" structure seems to be a persistent feature However, there has been an increasing awareness of the fact that the applied reconstruction methods underestimate the low-frequency variability and trends. The recognition of the inadequacies of the reconstruction methods has to a large degree originated from pseudo-proxy studies, i.e., from long climate model experiments where artificial proxies have been generated and reconstructions based on these have been compared to the known model climate. It has also been found that reconstructions contain a large element of stochasticity which is revealed as broad distributions of skills. This means that it is very difficult to draw conclusions from a single or a few realizations. Climate reconstruction methods are based on variants of linear regression models relating temperatures and proxies. In this contribution we review some of the theory of linear regression and error-in-variables models to identify the sources of the underestimation of variability. Based on the gained insight we formulate a reconstruction method supposed to minimize this underestimation. The method is tested by applying it to an ensemble of surrogate temperature fields based on two climate simulations covering the last 500 and 1000 years. Compared to the RegEM TTLS method and a composite plus scale method - two methods recently used in the literature - the new method strongly improves the behavior regarding the low-frequency variability and trends. The potential importance in real world situations is demonstrated by implying the methods to a set of 14 decadal smoothed proxies. Here the new method shows much larger low-frequency variability and a much colder pre-industrial temperature level than the other reconstruction methods.

  11. Top-of-atmosphere radiative contribution to unforced decadal global temperature variability in climate models

    NASA Astrophysics Data System (ADS)

    Brown, Patrick T.; Li, Wenhong; Li, Laifang; Ming, Yi

    2014-07-01

    Much recent work has focused on unforced global mean surface air temperature (T) variability associated with the efficiency of heat transport into the deep ocean. Here the relationship between unforced variability in T and the Earth's top-of-atmosphere (TOA) energy balance is explored in preindustrial control runs of the Coupled Model Intercomparison Project Phase 5 multimodel ensemble. It is found that large decadal scale variations in T tend to be significantly enhanced by the net energy flux at the TOA. This indicates that unforced decadal variability in T is not only caused by a redistribution of heat within the climate system but can also be associated with unforced changes in the total amount of heat in the climate system. It is found that the net TOA radiation imbalances result mostly from changes in albedo associated with the Interdecadal Pacific Oscillation that temporarily counteracts the climate system's outgoing longwave (i.e., Stefan-Boltzmann) response to T change.

  12. Holocene Southern Ocean surface temperature variability west of the Antarctic Peninsula.

    PubMed

    Shevenell, A E; Ingalls, A E; Domack, E W; Kelly, C

    2011-02-10

    The disintegration of ice shelves, reduced sea-ice and glacier extent, and shifting ecological zones observed around Antarctica highlight the impact of recent atmospheric and oceanic warming on the cryosphere. Observations and models suggest that oceanic and atmospheric temperature variations at Antarctica's margins affect global cryosphere stability, ocean circulation, sea levels and carbon cycling. In particular, recent climate changes on the Antarctic Peninsula have been dramatic, yet the Holocene climate variability of this region is largely unknown, limiting our ability to evaluate ongoing changes within the context of historical variability and underlying forcing mechanisms. Here we show that surface ocean temperatures at the continental margin of the western Antarctic Peninsula cooled by 3-4 °C over the past 12,000 years, tracking the Holocene decline of local (65° S) spring insolation. Our results, based on TEX(86) sea surface temperature (SST) proxy evidence from a marine sediment core, indicate the importance of regional summer duration as a driver of Antarctic seasonal sea-ice fluctuations. On millennial timescales, abrupt SST fluctuations of 2-4 °C coincide with globally recognized climate variability. Similarities between our SSTs, Southern Hemisphere westerly wind reconstructions and El Niño/Southern Oscillation variability indicate that present climate teleconnections between the tropical Pacific Ocean and the western Antarctic Peninsula strengthened late in the Holocene epoch. We conclude that during the Holocene, Southern Ocean temperatures at the western Antarctic Peninsula margin were tied to changes in the position of the westerlies, which have a critical role in global carbon cycling. PMID:21307939

  13. Sea surface temperature variability over North Indian Ocean — A study of two contrasting monsoon seasons

    Microsoft Academic Search

    M. R. Ramesh Kumar; S. Sathyendranath; N. K. Viswambharan; L. V. Gangadhara Rao

    1986-01-01

    Using the satellite derived sea surface temperature (SST) data for 1979 (bad monsoon) and 1983 (good monsoon), the SST variability\\u000a for two contrasting monsoon seasons is studied. The study indicates that large negative anomalies off the Somali and Arabian\\u000a coasts are associated with good monsoon rainfall over India. The strong monsoonal cooling in these regions can be attributed\\u000a to strong

  14. Satellite-derived long-term variability of sea surface temperature in the Mediterranean Sea

    Microsoft Academic Search

    Nikolaos Skliris; Annita Mantziafou; Sarantis Sofianos; Athanasios Gkanasos; Panagiotis Aksaopoulos; Vasilis Vervatis

    2010-01-01

    Twenty four years of AVHRR-derived sea surface temperature (SST) daily data (1985-2008) are used to investigate the long-term variability of this parameter in the Mediterranean Sea. Results indicate a strong eastward increasing sea surface warming trend with a mean annual warming rate of about 0.035 °C\\/yr for the western sub-basin and of about 0.055 °C\\/yr for the eastern sub-basin. The

  15. Tropical Atlantic sea surface temperature variability and its relation to El Niño-Southern Oscillation

    Microsoft Academic Search

    David B. Enfield; Dennis A. Mayer

    1997-01-01

    Past analyses of tropical Atlantic sea surface temperature variability have suggested a dipole behavior between the northern and southern tropics, across the Intertropical Convergence Zone (ITCZ). By analyzing an improved 43-year (1950-1992) record of SST (Smith et al., 1996) and other data derived from the Comprehensive Ocean-Atmosphere Data Set (COADS), it is shown that the regions north and south of

  16. Statistical Variability and Persistence Change in Daily Air Temperature Time Series from High Latitude Arctic Stations

    NASA Astrophysics Data System (ADS)

    Suteanu, Cristian

    2015-07-01

    In the last decades, Arctic communities have been reporting that weather conditions are becoming less predictable. Most scientific studies have not been able to consistently confirm such a trend. The question regarding the possible increase in weather variability was addressed here based on daily minimum and maximum surface air temperature time series from 15 high latitude Arctic stations from Canada, Norway, and the Russian Federation. A range of analysis methods were applied, distinguished mainly by the way in which they treat time scale. Statistical L-moments were determined for temporal windows of different lengths. While the picture provided by L-scale and L-kurtosis is not consistent with an increasing variability, L-skewness was found to change towards more positive values, reflecting an enhancement of warm spells. Haar wavelet analysis was applied both to the entire time series and to running windows. Persistence diagrams were generated based on running windows advancing through time and on local slopes of Haar analysis graphs; they offer a more nuanced view on variability by reflecting its change over time on a range of temporal scales. Local increases in variability could be identified in some cases, but no consistent change was detected in any of the stations over the studied temporal scales. The possibility for other intervals of temporal scale (e.g., days, hours, minutes) to potentially reveal a different situation cannot be ruled out. However, in the light of the results presented here, explanations for the discrepancy between variability perception and results of pattern analysis might have to be explored using an integrative approach to weather variables such as air temperature, cloud cover, precipitation, wind, etc.

  17. Variability of maximum and mean average temperature across Libya (1945-2009)

    NASA Astrophysics Data System (ADS)

    Ageena, I.; Macdonald, N.; Morse, A. P.

    2014-08-01

    Spatial and temporal variability in daily maximum and mean average daily temperature, monthly maximum and mean average monthly temperature for nine coastal stations during the period 1956-2009 (54 years), and annual maximum and mean average temperature for coastal and inland stations for the period 1945-2009 (65 years) across Libya are analysed. During the period 1945-2009, significant increases in maximum temperature (0.017 °C/year) and mean average temperature (0.021 °C/year) are identified at most stations. Significantly, warming in annual maximum temperature (0.038 °C/year) and mean average annual temperatures (0.049 °C/year) are observed at almost all study stations during the last 32 years (1978-2009). The results show that Libya has witnessed a significant warming since the middle of the twentieth century, which will have a considerable impact on societies and the ecology of the North Africa region, if increases continue at current rates.

  18. Tree growth and inferred temperature variability at the North American Arctic treeline

    NASA Astrophysics Data System (ADS)

    D'Arrigo, Rosanne; Jacoby, Gordon; Buckley, Brendan; Sakulich, John; Frank, David; Wilson, Rob; Curtis, Ashley; Anchukaitis, Kevin

    2009-01-01

    We present white spruce ( Picea glauca) tree-ring width and maximum latewood density chronologies for two latitudinal treeline sites in northern interior Canada: along the Coppermine River in the Northwest Territories (NWT); and in the Thelon River Sanctuary, Nunavut. These chronologies provide climate and tree growth information for these two remote locations, filling a sizeable gap in spatial coverage of proxy records used to reconstruct temperature variability for the Northern Hemisphere. They represent some of the longest high-resolution proxies available for northern North America, dating as far back as AD 1046 for Coppermine ring widths. These chronologies correlate significantly with hemispheric-scale annual temperature reconstructions for the past millennium. Density records from both sites show a positive relationship with warm-season temperature data since ˜ the mid-20th century, although this link is somewhat weaker in recent decades (since ˜ 1980). Both ring-width chronologies demonstrate even greater loss of temperature sensitivity, and in the Thelon ring-width series a sustained reduction in growth appears linked to increased drought stress in this recent period. Diminishing correlations with temperature are also found when the Thelon ring-width and climate data are prewhitened, indicating that any low frequency uncertainties in the instrumental or tree-ring data (e.g., artifacts from the standardization process) cannot entirely account for this result. Our findings therefore suggest a recent loss of temperature sensitivity at these northern treeline locations that varies with the parameter and site studied. These and other uncertainties in the tree-ring as well as instrumental data will need to be resolved in future efforts to relate northern tree-ring records to temperature variability on a range of spatial scales.

  19. Continental-scale temperature variability in PMIP3 simulations and PAGES 2k regional temperature reconstructions over the past millennium

    NASA Astrophysics Data System (ADS)

    Pages2k-Pmip3 Group

    2015-06-01

    Estimated external radiative forcings, model results and proxy-based climate reconstructions have been used over the past several decades to improve our understanding of the mechanisms underlying observed climate variability and change over the past millennium. Here, the recent set of temperature reconstructions at the continental-scale generated by the PAGES 2k project and the collection of state-of-the-art model simulations driven by realistic external forcings following the PMIP3 protocol are jointly analysed. The first aim is to estimate the consistency between model results and reconstructions for each continental-scale region over time and frequency domains. Secondly, the links between regions are investigated to determine whether reconstructed global-scale covariability patterns are similar to those identified in model simulations. The third aim is to assess the role of external forcings in the observed temperature variations. From a large set of analyses, we conclude that models are in relatively good agreement with temperature reconstructions for Northern Hemisphere regions, particularly in the Arctic. This is likely due to the relatively large amplitude of the externally forced response across northern and high latitudes regions, which results in a clearly detectable signature in both reconstructions and simulations. Conversely, models disagree strongly with the reconstructions in the Southern Hemisphere. Furthermore, the simulations are more regionally coherent than the reconstructions perhaps due to an underestimation of the magnitude of internal variability in models or to an overestimation of the response to the external forcing in the Southern Hemisphere. Part of the disagreement might also reflect large uncertainties in the reconstructions, specifically in some Southern Hemisphere regions which are based on fewer paleoclimate records than in the Northern Hemisphere.

  20. Temperature and acidification variability reduce physiological performance in the intertidal zone porcelain crab Petrolisthes cinctipes.

    PubMed

    Paganini, Adam W; Miller, Nathan A; Stillman, Jonathon H

    2014-11-15

    We show here that increased variability of temperature and pH synergistically negatively affects the energetics of intertidal zone crabs. Under future climate scenarios, coastal ecosystems are projected to have increased extremes of low tide-associated thermal stress and ocean acidification-associated low pH, the individual or interactive effects of which have yet to be determined. To characterize energetic consequences of exposure to increased variability of pH and temperature, we exposed porcelain crabs, Petrolisthes cinctipes, to conditions that simulated current and future intertidal zone thermal and pH environments. During the daily low tide, specimens were exposed to no, moderate or extreme heating, and during the daily high tide experienced no, moderate or extreme acidification. Respiration rate and cardiac thermal limits were assessed following 2.5 weeks of acclimation. Thermal variation had a larger overall effect than pH variation, though there was an interactive effect between the two environmental drivers. Under the most extreme temperature and pH combination, respiration rate decreased while heat tolerance increased, indicating a smaller overall aerobic energy budget (i.e. a reduced O2 consumption rate) of which a larger portion is devoted to basal maintenance (i.e. greater thermal tolerance indicating induction of the cellular stress response). These results suggest the potential for negative long-term ecological consequences for intertidal ectotherms exposed to increased extremes in pH and temperature due to reduced energy for behavior and reproduction. PMID:25392458

  1. Global-scale modes of surface temperature variability on interannual to century timescales

    NASA Technical Reports Server (NTRS)

    Mann, Michael E.; Park, Jeffrey

    1994-01-01

    Using 100 years of global temperature anomaly data, we have performed a singluar value decomposition of temperature variations in narrow frequency bands to isolate coherent spatio-temporal modes of global climate variability. Statistical significance is determined from confidence limits obtained by Monte Carlo simulations. Secular variance is dominated by a globally coherent trend; with nearly all grid points warming in phase at varying amplitude. A smaller, but significant, share of the secular variance corresponds to a pattern dominated by warming and subsequent cooling in the high latitude North Atlantic with a roughly centennial timescale. Spatial patterns associated with significant peaks in variance within a broad period range from 2.8 to 5.7 years exhibit characteristic El Nino-Southern Oscillation (ENSO) patterns. A recent transition to a regime of higher ENSO frequency is suggested by our analysis. An interdecadal mode in the 15-to-18 years period and a mode centered at 7-to-8 years period both exhibit predominantly a North Atlantic Oscillation (NAO) temperature pattern. A potentially significant decadal mode centered on 11-to-12 years period also exhibits an NAO temperature pattern and may be modulated by the century-scale North Atlantic variability.

  2. Variable-temperature cryogenic trap for the separation of gas mixtures

    NASA Technical Reports Server (NTRS)

    Des Marais, D. J.

    1978-01-01

    The paper describes a continuous variable-temperature U-shaped cold trap which can both purify vacuum-line combustion products for subsequent stable isotopic analysis and isolate the methane and ethane constituents of natural gases. The canister containing the trap is submerged in liquid nitrogen, and, as the gas cools, the gas mixture components condense sequentially according to their relative vapor pressures. After the about 12 min required for the bottom of the trap to reach the liquid-nitrogen temperature, passage of electric current through the resistance wire wrapped around the tubing covering the U-trap permits distillation of successive gas components at optimal temperatures. Data on the separation achieved for two mixtures, the first being typical vacuum-line combustion products of geochemical samples such as rocks and the second being natural gas, are presented, and the thermal behavior and power consumption are reported.

  3. Influence of cosmic-ray variability on the monsoon rainfall and temperature

    NASA Astrophysics Data System (ADS)

    Badruddin; Aslam, O. P. M.

    2015-01-01

    We study the role of galactic cosmic ray (GCR) variability in influencing the rainfall variability in Indian Summer Monsoon Rainfall (ISMR) season. We find that on an average during 'drought' (low ISMR) periods in India, GCR flux is decreasing, and during 'flood' (high ISMR) periods, GCR flux is increasing. The results of our analysis suggest for a possibility that the decreasing GCR flux during the summer monsoon season in India may suppress the rainfall. On the other hand, increasing GCR flux may enhance the rainfall. We suspect that in addition to real environmental conditions, significant levitation/dispersion of low clouds and hence reduced possibility of collision/coalescence to form raindrops suppresses the rainfall during decreasing GCR flux in monsoon season. On the other hand, enhanced collision/coalescence efficiency during increasing GCR flux due to electrical effects may contribute to enhancing the rainfall. Based on the observations, we put forward the idea that, under suitable environmental conditions, changing GCR flux may influence precipitation by suppressing/enhancing it, depending upon the decreasing/increasing nature of GCR flux variability during monsoon season in India, at least. We further note that the rainfall variability is inversely related to the temperature variation during ISMR season. We suggest an explanation, although speculative, how a decreasing/increasing GCR flux can influence the rainfall and the temperature. We speculate that the proposed hypothesis, based on the Indian climate data can be extended to whole tropical and sub-tropical belt, and that it may contribute to global temperature in a significant way. If correct, our hypothesis has important implication for the sun - climate link.

  4. Testing of a Loop Heat Pipe Subjective to Variable Accelerations. Part 2; Temperature Stability

    NASA Technical Reports Server (NTRS)

    Ku, Jentung; Ottenstein, Laura; Kaya, Taril; Rogers, Paul; Hoff, Craig

    2000-01-01

    The effect of accelerating forces on the performance of loop heat pipes (LHP) is of interest and importance to terrestrial and space applications. LHP's are being considered for cooling of military combat vehicles and for spinning spacecraft. In order to investigate the effect of an accelerating force on LHP operation, a miniature LHP was installed on a spin table. Variable accelerating forces were imposed on the LHP by spinning the table at different angular speeds. Several patterns of accelerating forces were applied, i.e. continuous spin at different speeds and periodic spin at different speeds and frequencies. The resulting accelerations ranged from 1.17 g's to 4.7 g's. This paper presents the second part of the experimental study, i.e. the effect of an accelerating force on the LHP operating temperature. It has been known that in stationary tests the LHP operating temperature is a function of the evaporator power and the condenser sink temperature when the compensation temperature is not actively controlled. Results of this test program indicate that any change in the accelerating force will result in a chance in the LHP operating temperature through its influence on the fluid distribution in the evaporator, condenser and compensation chamber. However, the effect is not universal, rather it is a function of other test conditions. A steady, constant acceleration may result in an increase or decrease of the operating temperature, while a periodic spin will lead to a quasi-steady operating temperature over a sufficient time interval. In addition, an accelerating force may lead to temperature hysteresis and changes in the temperature oscillation. In spite of all these effects, the LHP continued to operate without any problems in all tests.

  5. Temperature and Rainfall Variability in the Northern Andes Over the Past Two Millennia

    NASA Astrophysics Data System (ADS)

    Shanahan, T. M.; Bixler, C. W.; Mora, A.

    2014-12-01

    Recent studies of tropical glaciers have shown that most are retreating rapidly, with some of the most dramatic changes occurring since the mid-1970s, most likely as a result of increasing global temperatures. However, a longer-term perspective is needed to place these changes in the context of natural climate variability. To better understand the climatological factors driving long-term variations in the mass balance of tropical glaciers, we reconstructed changes in precipitation and temperature in the northern tropical Andes using variations in the hydrogen isotope composition of sedimentary leaf waxes and branched GDGT distributions in a high-resolution varved sediment record from Lago Chingaza, Colombia. Br-GDGT derived temperatures are significantly correlated with instrumental temperature data and indicate that recent warming in the northern tropical Andes is unprecedented over the past two millennia. Furthermore, the magnitude of warming since the Little Ice Age is substantially larger than suggested by high latitude temperature reconstructions. Hydrogen isotope data indicated that colder conditions during the Little Ice Age were accompanied by a decrease in rainfall, likely associated with a southward shift in the position of the ITCZ. Over the past few centuries, warmer temperatures were accompanied by an increase in rainfall and a northward expansion of the tropical rainbelt. Together, these data suggest that the dominant control on the retreat of Andean glaciers has been the unprecedented rate and magnitude of recent warming.

  6. Temperature and hydrologic variability of Lake Victoria, East Africa since the Late Pleistocene

    NASA Astrophysics Data System (ADS)

    Berke, M. A.; Johnson, T. C.; Werne, J. P.; Schouten, S.; Sinninghe Damste, J. S.

    2010-12-01

    Recent organic geochemical advances have facilitated the comparison between continental temperature change and hydrologic variability. TEX86, a proxy based on the lipids of aquatic Crenarchaeota that show a positive correlation with growth temperature, was used to reconstruct surface water temperatures from Lake Victoria, East Africa during the latest Pleistocene-Holocene. Hydrologic conditions were interpreted using paleoecological implications of shifting pollen and diatom assemblages found in the lake (Kendall, 1969; Stager et al., 2003) and will be compared with future compound specific ?13C data from terrestrial biomarkers in order to determine the patterns of rainfall and aridity in this region. Initial comparisons of climatic changes seen in temperature and hydrologic records appear to show consistency between warm/wet intervals and cool/dry intervals that is often assumed, but more rarely shown, in tropical Africa. Lake Victoria temperatures show a steady warming beginning 16 cal ka, with a pause around the Younger Dryas, dominated by arid conditions and strong savannah grassland development during this interval. There is continued warming to a sustained thermal maximum for this portion of the record at ~10.5-8.5 ka, which generally coincides with the beginning of the Holocene Hypsithermal, an interval of elevated temperatures and precipitation throughout much of tropical Africa. This thermal maximum occurs during the most humid interval of this record (~9.5-8.3 ka), shown by an increase of humid forest pollen and high diatom abundance (due to increased water column mixing and nutrient runoff). Temperatures abruptly cool ~1.5°C in <800 years while precipitation becomes somewhat more seasonally restricted, coinciding with an abrupt drop in inferred P:E ratio and reduction in wind-driven mixing. The record then shows a general cooling, reaching a Holocene thermal minimum of ~18.4°C at ~4.5 ka, contrary to other East African continental and marine paleoclimate records that exhibit a Holocene thermal maximum ~5 ka. These coolest Holocene temperatures correspond to the driest interval in the surrounding region (~5.8-2.7 ka), with an increase in grassland abundance and decrease in humid forest pollen. Though a 5 ka thermal maximum is not seen in Lake Victoria, this portion of the record shows a temperature inflection and variable hydrologic signals, potentially marking a response to the end of the Holocene Hypsithermal, where temperatures begin to rise ~3°C over the remainder of the record.

  7. Local-scale spatial modelling for interpolating climatic temperature variables to predict agricultural plant suitability

    NASA Astrophysics Data System (ADS)

    Webb, Mathew A.; Hall, Andrew; Kidd, Darren; Minansy, Budiman

    2015-05-01

    Assessment of local spatial climatic variability is important in the planning of planting locations for horticultural crops. This study investigated three regression-based calibration methods (i.e. traditional versus two optimized methods) to relate short-term 12-month data series from 170 temperature loggers and 4 weather station sites with data series from nearby long-term Australian Bureau of Meteorology climate stations. The techniques trialled to interpolate climatic temperature variables, such as frost risk, growing degree days (GDDs) and chill hours, were regression kriging (RK), regression trees (RTs) and random forests (RFs). All three calibration methods produced accurate results, with the RK-based calibration method delivering the most accurate validation measures: coefficients of determination (R 2) of 0.92, 0.97 and 0.95 and root-mean-square errors of 1.30, 0.80 and 1.31 °C, for daily minimum, daily maximum and hourly temperatures, respectively. Compared with the traditional method of calibration using direct linear regression between short-term and long-term stations, the RK-based calibration method improved R 2 and reduced root-mean-square error (RMSE) by at least 5 % and 0.47 °C for daily minimum temperature, 1 % and 0.23 °C for daily maximum temperature and 3 % and 0.33 °C for hourly temperature. Spatial modelling indicated insignificant differences between the interpolation methods, with the RK technique tending to be the slightly better method due to the high degree of spatial autocorrelation between logger sites.

  8. The influence of the North Atlantic Oscillation on the regional temperature variability in Sweden: spatial and temporal variations

    Microsoft Academic Search

    Deliang Chen; Cecilia Hellström

    1999-01-01

    A statistical analysis of the seasonal and interannual variations in the regional temperature anomalies of Sweden during 1861 1994 is performed. The study uses homogenized monthly temperatures averaged over 6 regions to minimize the non climatic and local-scale climatic effects. It is found that the temperature variability shows a clear regional and seasonal dependency. The topography, the influence of the

  9. A case of sudden variation in nocturnal mesospheric temperatures: variability and its causative mechanism

    NASA Astrophysics Data System (ADS)

    Taori, Alok; Kesarkar, Amit; Kumar, Niranjan; Thokuluwa, Ramkumar

    In general, nocturnal mesospheric temperatures show long period tidal oscillations to dominate in the night-time airglow observations due to its natural variability. However various forcing owing to thermally or mechanically generated waves in the lower atmosphere have been under-stood to perturb the mesospheric variability. It is also observed that the convective episode occurred in the lower atmosphere are responsible to perturb the frequency of waves observed over mesosphere. In this work, we analyze nocturnal observations recorded by mesosphere lower thermosphere photometer (MLTP) on April 21, 22 and 27, 2009 over Gadanki (13.5 N, 79.2 E), Andhra Pradesh, India. It is observed that due to the passage of cyclone Bijili during the above men-tioned period and convections observed over Indian subcontinent generated from its remnants cause the generation of period waves in the mesosphere. It is noted that the nature of OH and O2 nocturnal variation reversed on the nights of 27th compared to the 22nd and 23rd April. To understand the vertical transport of the energy in terms of short period wave we have analyzed the COSMIC (constellation observing system for meteorology ionosphere climate) temperature profiles of normalized temperature perturbations and OLR (outgoing long-wave radiation) mea-surements. The results obtained from this clearly indicate that energy flux inflow in mesosphere from lower atmosphere is caused by ongoing troposphere disturbed the mesosphere.

  10. Temporal variability of temperature-nitrate relationship in a coastal region

    NASA Astrophysics Data System (ADS)

    Yin, Jianping; Lin, Li; Wang, Youshao; Du, Jianwei

    2014-07-01

    The inverse relationship between nitrate and temperature (N-T relationship) has been used to estimate new production from remotely sensed sea surface temperature at the regional or global scale of oceans. This study aimed to develop a time-series model of the N-T relationship from automated, continuous hourly observations over two years on the coast of Halifax, Canada. The model demonstrated time-series variability of the N-T relationship at a coastal station on the Nova Scotia Shelf, with adjusted R 2 =0.999 4 and RMSE=0.025 7. The maximum residual value was 0.077. The annual temperature variations described a sine curve, and daily, weekly, and monthly variations fluctuated within the normal ranges, controlled by the local climate. The annual variation of nitrate concentration formed nearly a sine curve. Heavy or longlasting rainfall increased nitrate concentration by 4 to 30-fold in 24 h, and then the increased nitrogen was quickly depleted by phytoplankton growth in 10 to 48 h. In general, biological activity was a key factor in causing nitrate concentration change, dependent mainly on seawater temperature. The power function of the N-T relationship observed in our study area could be used to quickly estimate sea surface nitrate concentration, in combination with temperature data obtained by remote sensing.

  11. Dynamics and thermodynamics of crystalline polymorphs. 2. ?-Glycine, analysis of variable-temperature atomic displacement parameters.

    PubMed

    Aree, Thammarat; Bürgi, Hans-Beat; Minkov, Vasily S; Boldyreva, Elena V; Chernyshov, Dmitry; Törnroos, Karl W

    2013-08-22

    The molecular dynamics in the crystal and the thermodynamic functions of the ?-polymorph of glycine have been determined from a combination of molecular translation-libration frequencies reflecting the temperature dependence of atomic displacement parameters (ADPs), with frequencies derived from ONIOM(DFT:PM3) calculations on a 15-molecule ?-glycine cluster. ADPs have been obtained from variable-temperature diffraction data to 0.5 Å resolution collected with X-ray synchrotron (10-300 K) and sealed tube radiation (50-298 K). At the higher temperatures, the ADPs of ?-glycine from synchrotron are larger than those from sealed tube probably due to different experimental conditions. The lattice vibration frequencies from normal-mode analysis of ADPs and the internal vibration frequencies from ONIOM(B3LYP/6-311+G(2d,p):PM3) calculations agree with those from spectroscopy. Estimation of thermodynamic functions using the vibrational frequencies, the Einstein and Debye models of heat capacity, and the room-temperature compressibility provides C(p), H(vib), and S(vib) that agree with those from calorimetry. The ?-phase with higher H and G is found to be less stable than the ?-phase in the temperature range of the experiment. PMID:23865724

  12. An internal variable constitutive model for the large deformation of metals at high temperatures

    NASA Technical Reports Server (NTRS)

    Brown, Stuart; Anand, Lallit

    1988-01-01

    The advent of large deformation finite element methodologies is beginning to permit the numerical simulation of hot working processes whose design until recently has been based on prior industrial experience. Proper application of such finite element techniques requires realistic constitutive equations which more accurately model material behavior during hot working. A simple constitutive model for hot working is the single scalar internal variable model for isotropic thermal elastoplasticity proposed by Anand. The model is recalled and the specific scalar functions, for the equivalent plastic strain rate and the evolution equation for the internal variable, presented are slight modifications of those proposed by Anand. The modified functions are better able to represent high temperature material behavior. The monotonic constant true strain rate and strain rate jump compression experiments on a 2 percent silicon iron is briefly described. The model is implemented in the general purpose finite element program ABAQUS.

  13. Higher trends but larger uncertainty and geographic variability in 21st century temperature and heat waves

    SciTech Connect

    Ganguly, Auroop R [ORNL; Steinhaeuser, Karsten J K [ORNL; Erickson III, David J [ORNL; Branstetter, Marcia L [ORNL; Parish, Esther S [ORNL; Singh, Nagendra [ORNL; Drake, John B [ORNL; Buja, Lawrence [ORNL

    2009-01-01

    Generating credible climate change and extremes projections remains a high-priority challenge, especially since recent observed emissions are above the worst-case scenario. Bias and uncertainty analyses of ensemble simulations from a global earth systems model show increased warming and more intense heat waves combined with greater uncertainty and large regional variability in the 21st century. Global warming trends are statistically validated across ensembles and investigated at regional scales. Observed heat wave intensities in the current decade are larger than worst-case projections. Model projections are relatively insensitive to initial conditions, while uncertainty bounds obtained by comparison with recent observations are wider than ensemble ranges. Increased trends in temperature and heat waves, concurrent with larger uncertainty and variability, suggest greater urgency and complexity of adaptation or mitigation decisions.

  14. The equatorial Atlantic sea surface temperature variability during the last millennium

    NASA Astrophysics Data System (ADS)

    Prado, Luciana; Wainer, Ilana; Khodri, Myriam

    2014-05-01

    The study of the variability patterns of the South Atlantic Basin is necessary to understand and predict the global climate because of its fundamental role in global climate control through heat transport to the North. As early as 330 years ago, the importance of the continental heat budget on the equatorial Atlantic Ocean driving the trade winds in the Gulf of Guinea was identified. However, only five decades ago studies started to understand the effects of these air-sea interaction processes over the Atlantic sector. More specifically, changes in continental rainfall are linked to the interannual variability of the equatorial Atlantic sea surface temperature, which is related to the Atlantic Niño. Here we aim to examine air-sea interaction processes in the tropical Atlantic region during key periods within the Last Millennium (LM, 850 to 1,850 Common Era, C.E.). This will be achieved by computing an index to the variability of the equatorial Atlantic sea surface temperature during the LM. This variability pattern will be obtained from the National Center for Atmospheric Research - Community Climate System Model, version 4 (NCAR-CCSM4.0) and the Institut Pierre Simon Laplace - Climate Model version 5A, low resolution (IPSL-CM5A-LR) transient runs. We expect to use this index to identify possible differences in the sea surface field between the Medieval Climate Anomaly (MCA, 950 to 1,250 C.E.) and the Little Ice Age (LIA, 1,400 to 1,700 C.E.).

  15. An evaluation of the effect of recent temperature variability on the prediction of coral bleaching events.

    PubMed

    Donner, Simon D

    2011-07-01

    Over the past 30 years, warm thermal disturbances have become commonplace on coral reefs worldwide. These periods of anomalous sea surface temperature (SST) can lead to coral bleaching, a breakdown of the symbiosis between the host coral and symbiotic dinoflagellates which reside in coral tissue. The onset of bleaching is typically predicted to occur when the SST exceeds a local climatological maximum by 1 degrees C for a month or more. However, recent evidence suggests that the threshold at which bleaching occurs may depend on thermal history. This study uses global SST data sets (HadISST and NOAA AVHRR) and mass coral bleaching reports (from Reefbase) to examine the effect of historical SST variability on the accuracy of bleaching prediction. Two variability-based bleaching prediction methods are developed from global analysis of seasonal and interannual SST variability. The first method employs a local bleaching threshold derived from the historical variability in maximum annual SST to account for spatial variability in past thermal disturbance frequency. The second method uses a different formula to estimate the local climatological maximum to account for the low seasonality of SST in the tropics. The new prediction methods are tested against the common globally fixed threshold method using the observed bleaching reports. The results find that estimating the bleaching threshold from local historical SST variability delivers the highest predictive power, but also a higher rate of Type I errors. The second method has the lowest predictive power globally, though regional analysis suggests that it may be applicable in equatorial regions. The historical data analysis suggests that the bleaching threshold may have appeared to be constant globally because the magnitude of interannual variability in maximum SST is similar for many of the world's coral reef ecosystems. For example, the results show that a SST anomaly of 1 degrees C is equivalent to 1.73-2.94 standard deviations of the maximum monthly SST for two-thirds of the world's coral reefs. Coral reefs in the few regions that experience anomalously high interannual SST variability like the equatorial Pacific could prove critical to understanding how coral communities acclimate or adapt to frequent and/or severe thermal disturbances. PMID:21830713

  16. Effects of temperature and moisture variability on soil CO2 emissions in European land ecosystems

    NASA Astrophysics Data System (ADS)

    Gritsch, C.; Zechmeister-Boltenstern, S.

    2014-12-01

    Soil respiration is one of the largest terrestrial fluxes of carbon dioxide (CO2) to the atmosphere. Hence, small changes in soil respiration rates could have large effects on atmospheric CO2. In order to assess CO2 emissions from diverse European soils under different land-use and climate (soil moisture and temperature) we conducted a laboratory incubation experiment. Therefore, we incubated soil cores (Ø 7 cm; height 7 cm) from nine European sites which are spread all over Europe; from the United Kingdom (west) to the Ukraine (east) and Italy (south) to Finland (north). In addition these sites can be clearly distinguished between their land use into forests, arable lands, grasslands and one peat land. Soil cores were incubated in a two-factorial experimental design at 5 different temperatures (5, 10, 15, 20, and 25°C) and 6 different moisture contents (5, 20, 40, 60, 80, and 100 % water filled pore space (WFPS)). An automated laboratory incubation measurement system was used to measure CO2 emissions. Results show that highest CO2 emissions occurred with intermediate moisture content (40% to 70%) over all sites. We found that the relationship between CO2 emissions and temperature could be well described by a Gaussian model (R² ranges from 0.87 to 1) over all sites. In general CO2 emissions were strongly related with both variables temperature and moisture. Temperature sensitivity (Q10) was negatively correlated with temperature for all land-uses investigated. Moisture sensitivity was calculated as the slope of a quadratic function and showed highest values at very low and high moisture content for all land-uses investigated. Moisture sensitivity was increasing with temperature for all arable lands investigated. All coniferous forest sites investigated showed a strong increase of the temperature sensitivity at lower temperatures at a moisture range of 20 - 40 % WFPS. In summary our results showed not only the relationship between temperature sensitivity of CO2 emissions and moisture content for a broad range of land-uses within Europe but also investigated the relationship between moisture sensitivity of CO2 emissions and temperature for said land-uses for the first time.

  17. Solid-state variable-temperature 1H MAS NMR studies on deuterated polyethylene.

    PubMed

    Chen, Q; Hurosu, H; Ando, I; Wu, X

    1997-02-01

    Solid-state variable-temperature/magic angle spinning (VT/MAS) 1H NMR measurements were carried out on deuterated polyethylene. From these experimental results it was found that the 1H chemical shift induced by conformational and morphological changes of the polyethylene sample is within the linewidth of approximately 0.5 ppm. Furthermore, from MAS/dipolar decoupling experiments it was found that the resonance frequency of the proton varies linearly with the inverse square of the deuterium decoupling power. This experimental finding is discussed theoretically. PMID:9176937

  18. Potential relation between equatorial sea surface temperatures and historic water level variability for Lake Turkana, Kenya

    NASA Astrophysics Data System (ADS)

    Bloszies, Chris; Forman, Steven L.

    2015-01-01

    Water level in Lake Turkana, Kenya in the past ca. 150 years is controlled primarily from the biannual passage of the East and West African Monsoon, with rainfall volume related partially to sea surface temperatures (SSTs) in the Western Indian and East Atlantic oceans. Empirical orthogonal function analyses show significant correlation between Eastern Atlantic or Western Indian SSTs and lake level anomalies, with the first mode accounting for 66% and 55% of the variability. The primary geographic loadings are consistent with a Gulf of Guinea moisture source and positive Indian Ocean Dipole (IOD) state. The second mode explains 10% of variability, and reflects the westward extension of an Indian Ocean cool pool, potentially indicative of a normal to a negative IOD state. There is significant spatial correlation between basin rainfall anomalies associated with Eastern Atlantic SSTs and a low in the continental divide between the Kenyan and the Ethiopian Highlands, which is a passage for moisture from the Congo Basin. Linear regression analysis with Bootstrap sampling and Monte Carlo simulations define numeric relations between Western Indian and Eastern Atlantic SSTs and lake level change for AD 1992-2013. The monthly and yearly lake level reconstructions based on this numeric analysis capture the decadal-scale variability and the 15 m drop in water level in the early 20th century. Meter-scale variability in lake level since ca. AD 1930 is associated with precipitation sourced from the Western Indian Ocean with IOD variability, whereas the 15 m drop in water level in the early 20th century may reflect a profound decrease in moisture from Atlantic/Congo Basin source. These numerical solutions are poised to reconstruct water level variations in the past ca. 300 years for Lake Turkana with new proxy records of SSTs from the Western Indian Ocean and the Gulf of Guinea.

  19. Simultaneous optoacoustic and laser-induced fluorescence studies at variable temperature

    SciTech Connect

    Beitz, J.V. [Argonne National Laboratory, IL (United States); Hinaus, B.M.; Huang, J. [Univ. of Wisconsin, Eau Claire, WI (United States)

    1993-12-31

    An apparatus that eliminates acoustic interference from scattered excitation light has been constructed. The design enables studies of air-sensitive or radioactive samples. The sample is immersed in helium gas in a cryostat. The temperature of the helium is variable from 4 K to 300 K without altering the temperature of the acoustic transducer that is external to the cryostat. A pulsed tunable dye laser is used as the excitation light source. Simultaneous collection of fluorescence and optoacoustic data is achieved using a multiwindow cryostat and a computer-based data acquisition system. The crystal-field splitting a 4f-electron state of Nd{sup 3+} in A-phase Nd{sub 2}O{sub 3} has been investigated using this apparatus.

  20. South Pacific Decadal Variability Since the 1790s and Changes in Earth Surface Temperature

    NASA Astrophysics Data System (ADS)

    Linsley, B. K.; Wu, H. C.; Dassie, E. P.; Schrag, D. P.

    2014-12-01

    Changes in oceanic heat storage may be partly responsible for the most recent stall (or hiatus) in rising Earth surface temperatures since ~2000 C.E. Instrumental data indicates that this most recent stall is coincident with a phase reversal of the North Pacific Decadal Oscillation (PDO). The main locations for this heat exchange with the atmosphere appear to be the tropical and mid-latitude regions of the surface ocean, primarily in the Pacific. We have been investigating poorly understood decadal surface ocean variability in the South Pacific Convergence Zone (SPCZ) region. Despite very sparse instrumental water temperature data in the South Pacific to define the decadal changes at the sea surface and in the upper water column, the available data suggests a disproportionately large role of the Southwest Pacific in decadal-scale changes in heat sequestration. We have generated coral Sr/Ca-derived sea surface temperature (SST) time-series extending back to 1791 C.E. from Fiji, Tonga and Rarotonga (FTR) in the SPCZ region of the subtropical Southwest Pacific and show that decadal-scale SST fluctuations in this broad region are concurrent with the PDO at least since ~1930 C.E. Beginning in the mid-20th century, when more reliable instrumental temperature and ocean heat content data exist, decades of warmer South Pacific subtropical SST co-occur with elevated South Pacific upper ocean (0-700m) heat content. These decadal-scale South Pacific warming events coincide with decadal-scale stalls or plateaus in rising global temperatures. Cross wavelet coherence analysis reveals an increase in the frequency of decadal SST variability from a period near 30 years throughout the 1800s to ~20 years in the later half of the 20th century. Our results provide strong supporting evidence that decadal-scale changes in global surface temperatures are in-part, related to heat storage in the upper water column in the subtropical Pacific. Our results also suggest that decadal-scale stalls in rising global surface temperature are to be expected in the near-future and may be predictable.

  1. Variable-temperature solid-state NMR studies of iron(II) and iron(III) complexes 

    E-print Network

    Shepard, Patricia Arlene

    1989-01-01

    Fe(2-pic)&C12 EtQH at room temperature. This approach provides an excellent control over sample spin-state composition and allows all NMR relaxation measurements to be made at room temperature, thereby eliminating temperature... sequence. CT is the cross-polarization contact time. MH and MC denote the magnetization of the H and C nuclei, respectively. 2. Variable-temperature C CP/MAS spectra for Fe(2-pic)3C12 EtOH 31 Variable-composition C CP/MAS spectra for FexZnl x(2-pic)3C...

  2. Response of tropical sea surface temperature, precipitation, and tropical cyclone-related variables to changes in global and local forcing

    E-print Network

    Sobel, Adam

    A single-column model is used to estimate the equilibrium response of sea surface temperature (SST), precipitation, and several variables related to tropical cyclone (TC) activity to changes in both local and global forcing. ...

  3. The bi-variate frequency distribution of two concurrent climatic variables: a study of temperature and dew point

    E-print Network

    Zeitler, Jon William

    1991-01-01

    THE BI-VARIATE FREQUENCY DISTRIBUTION OF TWO CONCURRENT CLIMATIC VARIABLES: A STUDY OF TEMPERATURE AND DEW POINT A Thesis by ION WILLIAM ZEITLER Submitted to the Office of Graduate Studies of Texas ARM University in partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE December 1991 Major Subject: Meteorology THE BI-VARIATE FREQUENCY DISTRIBUTION OF TWO CONCURRENT CLIMATIC VARIABLES: A STUDY OF TEMPERATURE AND DEW POINT A Thesis by JON WILLIAM ZEITLER Approved...

  4. Long-Term Variability of Satellite Lake Surface Water Temperatures in the Great Lakes

    NASA Astrophysics Data System (ADS)

    Gierach, M. M.; Matsumoto, K.; Holt, B.; McKinney, P. J.; Tokos, K.

    2014-12-01

    The Great Lakes are the largest group of freshwater lakes on Earth that approximately 37 million people depend upon for fresh drinking water, food, flood and drought mitigation, and natural resources that support industry, jobs, shipping and tourism. Recent reports have stated (e.g., the National Climate Assessment) that climate change can impact and exacerbate a range of risks to the Great Lakes, including changes in the range and distribution of certain fish species, increased invasive species and harmful algal blooms, declining beach health, and lengthened commercial navigation season. In this study, we will examine the impact of climate change on the Laurentian Great Lakes through investigation of long-term lake surface water temperatures (LSWT). We will use the ATSR Reprocessing for Climate: Lake Surface Water Temperature & Ice Cover (ARC-Lake) product over the period 1995-2012 to investigate individual and interlake variability. Specifically, we will quantify the seasonal amplitude of LSWTs, the first and last appearances of the 4°C isotherm (i.e., an important identifier of the seasonal evolution of the lakes denoting winter and summer stratification), and interpret these quantities in the context of global interannual climate variability such as ENSO.

  5. Definition of predictor variables for MAP poultry filets stored under different temperature conditions.

    PubMed

    Herbert, Ulrike; Albrecht, Antonia; Kreyenschmidt, Judith

    2015-03-01

    Storage tests under different temperatures (2, 4, 10, and 15°C) were conducted to identify the best predictor variable that is most effective to explain the loss of the shelf life and quality of modified atmosphere packed (MAP) poultry, and constitutes the basis for the prediction of the remaining shelf life. The samples were packed in 70% O2 and 30% CO2, which is the common used gas atmosphere for poultry filets in Germany. Typical spoilage microorganisms (Pseudomonas spp., Brochothrix thermosphacta, Enterobacteriaceae, and Lactobacillus spp.) and total viable count (TVC) were enumerated frequently. Additionally, samples were analyzed for sensory changes, pH, and gas concentration. The data extraction and selections by stepwise regression and principle component analysis (PCA) was carried out to identify a variable which has the main influence on shelf life and freshness loss. The results accentuate that the spoilage is caused by a wide range of microorganisms. No specific microorganism could be identified as the dominant originator for the deteriorative changes. Solely TVC showed significant correlations between the development of the sensory decay and the development of the TVC for each single storage temperature. PMID:25638474

  6. Spatial and temporal variability of sea surface temperature and warming trends in the Yellow Sea

    NASA Astrophysics Data System (ADS)

    Park, Kyung-Ae; Lee, Eun-Young; Chang, Eunmi; Hong, Sungwook

    2015-03-01

    The spatial and temporal variability of sea surface temperatures (SST) in the Yellow Sea was investigated using satellite data and in-situ measurements over 29 years from 1981 to 2009. We found that the first empirical orthogonal function (EOF) mode of SST variability, which accounts for 47.59% of the total SST variance, exhibited a warming signal during the study period. We examined the relationships between the dominant EOF mode, long-term trends of SST changes and in-situ temperatures, and bathymetry. As a result, the shallow regions demonstrated more significant increasing rates than the deep area in the Yellow Sea. Vertical stratification of the water column revealed long-term changes, which led to differential surface warming. The warming rates decayed monotonically with depth. The spatial features of long-term SST warming trends were most remarkable near the Yangtze River, due to the effect of river discharge. Abrupt changes in the time-varying amplitude of the first EOF mode in winter could be explained by Arctic Oscillation.

  7. Seasonal differences in intraseasonal and interannual variability of Mediterranean Sea surface temperature

    NASA Astrophysics Data System (ADS)

    Zveryaev, Igor I.

    2015-04-01

    Sea surface temperature (SST) data from the NOAA OI SST data set for 1982-2011 are used to investigate intraseasonal and interannual variability of Mediterranean SST during winter and summer seasons. It is shown that during winter the intraseasonal SST fluctuations are larger than the interannual SST variations in the western Mediterranean (e.g., the Tyrrhenian Sea), but smaller in the central and eastern Mediterranean Sea. In summer, the intraseasonal SST fluctuations are larger in almost the entire Mediterranean basin. Also summertime intraseasonal SST fluctuations are larger (up to three times near the Gulf of Lions) than their wintertime counterparts in the entire Mediterranean basin. The interannual SST variations are larger during summer in the western and central Mediterranean Sea and during winter in its eastern part. The leading empirical orthogonal functions (EOFs) of the Mediterranean SST and of the intensities of its intraseasonal fluctuations are characterized by the differing spatial-temporal structures both during winter and summer implying that their interannual variability is driven by different physical mechanisms. During winter, the EOF-1 of SST is associated with the East Atlantic teleconnection, whereas EOF-1 of the intensity of intraseasonal fluctuations is not linked significantly to regional atmospheric dynamics. The second EOFs of these variables are associated, respectively, with the East Atlantic/West Russia and the North Atlantic teleconnections. While during summer the atmospheric influence on Mediterranean SST is generally weaker, it is revealed that the EOF-1 of the intensity of intraseasonal SST fluctuations is linked to the Polar teleconnection.

  8. Joint spatiotemporal variability of global sea surface temperatures and global Palmer drought severity index values

    USGS Publications Warehouse

    Apipattanavis, S.; McCabe, G.J.; Rajagopalan, B.; Gangopadhyay, S.

    2009-01-01

    Dominant modes of individual and joint variability in global sea surface temperatures (SST) and global Palmer drought severity index (PDSI) values for the twentieth century are identified through a multivariate frequency domain singular value decomposition. This analysis indicates that a secular trend and variability related to the El Niño–Southern Oscillation (ENSO) are the dominant modes of variance shared among the global datasets. For the SST data the secular trend corresponds to a positive trend in Indian Ocean and South Atlantic SSTs, and a negative trend in North Pacific and North Atlantic SSTs. The ENSO reconstruction shows a strong signal in the tropical Pacific, North Pacific, and Indian Ocean regions. For the PDSI data, the secular trend reconstruction shows high amplitudes over central Africa including the Sahel, whereas the regions with strong ENSO amplitudes in PDSI are the southwestern and northwestern United States, South Africa, northeastern Brazil, central Africa, the Indian subcontinent, and Australia. An additional significant frequency, multidecadal variability, is identified for the Northern Hemisphere. This multidecadal frequency appears to be related to the Atlantic multidecadal oscillation (AMO). The multidecadal frequency is statistically significant in the Northern Hemisphere SST data, but is statistically nonsignificant in the PDSI data.

  9. Analysis of Seasonal Snow Cover Changes in the Himalayan Region and the Associated Temperature Variability

    NASA Astrophysics Data System (ADS)

    Sun, M.; El-Askary, H. M.

    2013-12-01

    It has been noted that the Himalaya region and surrounding Tibetan Plateau are sensitive to climate change, due to their high altitude and large terrain. With the rising temperature recently glaciers has been facing fast-paced melting causing more lakes to expand and flood, yet it can cause the water source to deplete in the long term which pose a risk for high population in many countries. In this work we analyzed the snow cover change over the Tibetan Plateau area using MODIS snow cover products, to shed light on the characteristic of the snow cover distribution, and the relationship of snow cover change and temperature variability. Using monthly and 8-days snow cover data in association with temperature data over the Tibet plateau during 2003-2011, we observed a seasonal component. Seasonal (spring, summer, fall and winter) average snow cover maps showed a very uneven snow cover distribution over the Tibet Plateau. It mainly concentrated in the plateau south-eastern and western high mountain ridge, showing patch shape distribution. On the other hand Western Karakoram Mountains, the southern Himalayas and southeast Nyainqentanglha Mountains are snow cover areas of high values. The northern part of the Kunlun Mountains and Qaidam Basin, the distribution of snow is relatively less. The results show the seasonal change of snow over varies obviously, the minimum values are in summer, and the maximum values of snow cover are in spring and/or winter. It was found that the seasonal average temperature in the Tibetan Plateau from 2003 to 2011 varied evidently. The summer in 2006 had the highest temperature 14.02494°C and the lowest seasonal temperature was in 2003 winter -5.53981°C. The correlation coefficient between the monthly air temperature data from 2003 to 2011 with the same period of the Tibet plateau snow cover area is -0.7349. The results indicate that in the winter and spring, the snow cover area of the Tibet plateau and the temperature has negative correlation and it is not a simple linear relationship. Correlation coefficients of seasonal snow cover area and temperature change over Tibetan Plateau area during same time shows an inverse relationship.

  10. Spatio-temporal variability of the North Sea cod recruitment in relation to temperature and zooplankton.

    PubMed

    Nicolas, Delphine; Rochette, Sébastien; Llope, Marcos; Licandro, Priscilla

    2014-01-01

    The North Sea cod (Gadus morhua, L.) stock has continuously declined over the past four decades linked with overfishing and climate change. Changes in stock structure due to overfishing have made the stock largely dependent on its recruitment success, which greatly relies on environmental conditions. Here we focus on the spatio-temporal variability of cod recruitment in an effort to detect changes during the critical early life stages. Using International Bottom Trawl Survey (IBTS) data from 1974 to 2011, a major spatio-temporal change in the distribution of cod recruits was identified in the late 1990s, characterized by a pronounced decrease in the central and southeastern North Sea stock. Other minor spatial changes were also recorded in the mid-1980s and early 1990s. We tested whether the observed changes in recruits distribution could be related with direct (i.e. temperature) and/or indirect (i.e. changes in the quantity and quality of zooplankton prey) effects of climate variability. The analyses were based on spatially-resolved time series, i.e. sea surface temperature (SST) from the Hadley Center and zooplankton records from the Continuous Plankton Recorder Survey. We showed that spring SST increase was the main driver for the most recent decrease in cod recruitment. The late 1990s were also characterized by relatively low total zooplankton biomass, particularly of energy-rich zooplankton such as the copepod Calanus finmarchicus, which have further contributed to the decline of North Sea cod recruitment. Long-term spatially-resolved observations were used to produce regional distribution models that could further be used to predict the abundance of North Sea cod recruits based on temperature and zooplankton food availability. PMID:24551103

  11. Atmospheric controls on northeast Pacific temperature variability and change, 1900–2012

    PubMed Central

    Johnstone, James A.; Mantua, Nathan J.

    2014-01-01

    Over the last century, northeast Pacific coastal sea surface temperatures (SSTs) and land-based surface air temperatures (SATs) display multidecadal variations associated with the Pacific Decadal Oscillation, in addition to a warming trend of ?0.5–1 °C. Using independent records of sea-level pressure (SLP), SST, and SAT, this study investigates northeast (NE) Pacific coupled atmosphere–ocean variability from 1900 to 2012, with emphasis on the coastal areas around North America. We use a linear stochastic time series model to show that the SST evolution around the NE Pacific coast can be explained by a combination of regional atmospheric forcing and ocean persistence, accounting for 63% of nonseasonal monthly SST variance (r = 0.79) and 73% of variance in annual means (r = 0.86). We show that SLP reductions and related atmospheric forcing led to century-long warming around the NE Pacific margins, with the strongest trends observed from 1910–1920 to 1940. NE Pacific circulation changes are estimated to account for more than 80% of the 1900–2012 linear warming in coastal NE Pacific SST and US Pacific northwest (Washington, Oregon, and northern California) SAT. An ensemble of climate model simulations run under the same historical radiative forcings fails to reproduce the observed regional circulation trends. These results suggest that natural internally generated changes in atmospheric circulation were the primary cause of coastal NE Pacific warming from 1900 to 2012 and demonstrate more generally that regional mechanisms of interannual and multidecadal temperature variability can also extend to century time scales. PMID:25246555

  12. Sea surface temperature variability in southern Okinawa Trough during last 2700 years

    NASA Astrophysics Data System (ADS)

    Wu, Weichao; Tan, Wenbing; Zhou, Liping; Yang, Huan; Xu, Yunping

    2012-07-01

    Most of the temperature reconstructions for the past two millennia are based on proxy data from various sites on land. Here we present a bidecadal resolution record of sea surface temperature (SST) in Southern Okinawa Trough for the past ca. 2700 years by analyzing tetraether lipids of planktonic archaea in the ODP Hole 1202B, a site under the strong influence of Kuroshio Current and East Asian monsoon. The reconstructed SST anomalies generally coincided with previously reported late Holocene climate events, including the Roman Warm Period, Sui-Tang dynasty Warm Period, Medieval Warm Period, Current Warm Period, Dark Age Cold Period and Little Ice Age. However, the Medieval Warm Period usually thought to be a historical analogue for the Current Warm Period has a mean SST of 0.6-0.8°C lower than that of the Roman Warm Period and Sui-Tang dynasty Warm Period. Despite an increase since 1850 AD, the mean SST in the 20th century is still within the range of natural variability during the past 2700 years. A close correlation of SST in Southern Okinawa Trough with air temperature in East China, intensity of East Asian monsoon and the El-Niño Southern Oscillation index has been attributed to the fluctuations in solar output and oceanic-atmospheric circulation.

  13. Mediterranean summer air temperature variability and its connection to the large-scale atmospheric circulation and SSTs

    Microsoft Academic Search

    E. Xoplaki; J. F. González-Rouco; J. Luterbacher; H. Wanner

    2003-01-01

    The interannual and decadal variability of summer (June to September) air temperature over the Mediterranean area is analyzed for the period 1950 to 1999. The combined influence of the large-scale atmospheric circulation at different levels and thermic predictors (thickness patterns and Mediterranean SSTs) on station temperature data is assessed by means of optimal objective techniques. The validity of the statistical

  14. Temperature variability of the last 1000 years in Antarctica from inert gas isotopes

    NASA Astrophysics Data System (ADS)

    Orsi, Anais; Landais, Amaelle; Severinghaus, Jeffrey P.

    2015-04-01

    A large effort has been made to document the climate history of the last two thousand years, but there are still substantial gaps in the Southern Hemisphere, especially at high latitudes, where the changes in the climate are the largest. These gaps limit our understanding of the most fundamental driving mechanisms of the climate. In particular, the impact of solar minima on surface temperature is not fully understood. Here, we investigate the spatial structure of multi decadal climate variability in Antarctica, assess the significance of the Little Ice Age minimum documented elsewhere. We present a 1000 year temperature record at two sites in Antarctica: WAIS Divide (79°S, 112°W, 1766 m a.s.l), and Talos Dome (72°S, 159°E, 2315 m a.s.l), reconstructed from the combination of inert gas isotopes from the ice core and borehole temperature measurements. Borehole temperature provides an absolute estimate of long-term trends, while noble gases track decadal to centennial scale changes. This method provides a temperature reconstruction that is independent of water isotopes, and allows us to improve our understanding of water isotopes as a temperature proxy, and use them to track circulation changes. We find that there is a pronounced cooling trend over the last millennium at both sites, but it is stronger in East Antarctica (Talos Dome) than West Antarctica (WAIS-D). At WAIS Divide, we find that "Little Ice Age" cold period of 1400-1800 was 0.52°C colder than the last century, and that the recent warming trend (0.23°C/decade since 1960) has past analogs about every 200 years. At Talos Dome, the pronounced cooling trend over the whole record is not visible in the water isotope record, which suggests that there is a compensation of several sources of fractionation. Overall, both records are consistent with the idea that the solar minima and persistent volcanic activity of the Little Ice Age (1400-1850 A.D.) had a significant impact on the surface temperature in Antarctica. The feedbacks amplifying the forcing were likely stronger on the East Antarctic plateau than on the more marine-influenced West Antarctica.

  15. Development of a temperature-variable magnetic resonance imaging system using a 1.0 T yokeless permanent magnet

    NASA Astrophysics Data System (ADS)

    Terada, Y.; Tamada, D.; Kose, K.

    2011-10-01

    A temperature variable magnetic resonance imaging (MRI) system has been developed using a 1.0 T permanent magnet. A permanent magnet, gradient coils, radiofrequency coil, and shim coil were installed in a temperature variable thermostatic bath. First, the variation in the magnetic field inhomogeneity with temperature was measured. The inhomogeneity has a specific spatial symmetry, which scales linearly with temperature, and a single-channel shim coil was designed to compensate for the inhomogeneity. The inhomogeneity was drastically reduced by shimming over a wide range of temperature from -5 °C to 45 °C. MR images of an okra pod acquired at different temperatures demonstrated the high potential of the system for visualizing thermally sensitive properties.

  16. Characteristics of temperature rise in variable inductor employing magnetorheological fluid driven by a high-frequency pulsed voltage source

    NASA Astrophysics Data System (ADS)

    Lee, Ho-Young; Kang, In Man; Shon, Chae-Hwa; Lee, Se-Hee

    2015-05-01

    A variable inductor with magnetorheological (MR) fluid has been successfully applied to power electronics applications; however, its thermal characteristics have not been investigated. To evaluate the performance of the variable inductor with respect to temperature, we measured the characteristics of temperature rise and developed a numerical analysis technique. The characteristics of temperature rise were determined experimentally and verified numerically by adopting a multiphysics analysis technique. In order to accurately estimate the temperature distribution in a variable inductor with an MR fluid-gap, the thermal solver should import the heat source from the electromagnetic solver to solve the eddy current problem. To improve accuracy, the B-H curves of the MR fluid under operating temperature were obtained using the magnetic property measurement system. In addition, the Steinmetz equation was applied to evaluate the core loss in a ferrite core. The predicted temperature rise for a variable inductor showed good agreement with the experimental data and the developed numerical technique can be employed to design a variable inductor with a high-frequency pulsed voltage source.

  17. Amplification of Surface Temperature Trends and Variability in the Tropical Atmosphere

    NASA Astrophysics Data System (ADS)

    Santer, B. D.; Wigley, T. M. L.; Mears, C.; Wentz, F. J.; Klein, S. A.; Seidel, D. J.; Taylor, K. E.; Thorne, P. W.; Wehner, M. F.; Gleckler, P. J.; Boyle, J. S.; Collins, W. D.; Dixon, K. W.; Doutriaux, C.; Free, M.; Fu, Q.; Hansen, J. E.; Jones, G. S.; Ruedy, R.; Karl, T. R.; Lanzante, J. R.; Meehl, G. A.; Ramaswamy, V.; Russell, G.; Schmidt, G. A.

    2005-09-01

    The month-to-month variability of tropical temperatures is larger in the troposphere than at Earth's surface. This amplification behavior is similar in a range of observations and climate model simulations and is consistent with basic theory. On multidecadal time scales, tropospheric amplification of surface warming is a robust feature of model simulations, but it occurs in only one observational data set. Other observations show weak, or even negative, amplification. These results suggest either that different physical mechanisms control amplification processes on monthly and decadal time scales, and models fail to capture such behavior; or (more plausibly) that residual errors in several observational data sets used here affect their representation of long-term trends.

  18. Effect of extrusion variables (temperature, moisture) on the antinutrient components of cereal brans.

    PubMed

    Kaur, Satinder; Sharma, Savita; Singh, Baljit; Dar, B N

    2015-03-01

    The study was carried out, to explore the potentiality of extrusion technology for elimination of antinutritional components of cereal brans. Extrusion variables were moisture content (14, 17 and 20 %) and temperatures (115 °C, 140 °C, 165 °C). Phytic acid, polyphenols, oxalates, trypsin inhibitor, bulk density and color of brans after extrusion were analyzed. All four raw bran samples had high concentration of phytic acid, polyphenols, oxalates and trypsin inhibitors. Extrusion cooking was found effective in reduction of these antinutritients. Extrusion processing reduced the phytic acid by 54.51 %, polyphenol by 73.38 %, oxalates by 36.84 %, and trypsin inhibitor by 72.39 %. The heat treatment caused the highest reduction in polyphenols followed by trypsin inhibitors, phytic acid and oxalates. The highest reduction in antinutrients was observed at 140 °C and 20 % moisture content. Bulk density increased significantly compared to raw brans and increase in redness and decrease in yellowness of brans was observed after extrusion treatment. PMID:25745239

  19. Sahel rainfall and decadal to multi-decadal sea surface temperature variability

    NASA Astrophysics Data System (ADS)

    Mohino, Elsa; Janicot, Serge; Bader, Juergen

    2011-08-01

    Decadal Sahelian rainfall variability was mainly driven by sea surface temperatures (SSTs) during the twentieth century. At the same time SSTs showed a marked long-term global warming (GW) trend. Superimposed on this long-term trend decadal and multi-decadal variability patterns are observed like the Atlantic Multidecadal Oscillation (AMO) and the inter-decadal Pacific Oscillation (IPO). Using an atmospheric general circulation model we investigate the relative contribution of each component to the Sahelian precipitation variability. To take into account the uncertainty related to the use of different SST data sets, we perform the experiments using HadISST1 and ERSSTv3 reconstructed sets. The simulations show that all three SST signals have a significant impact over West Africa: the positive phases of the GW and the IPO lead to drought over the Sahel, while a positive AMO enhances Sahel rainfall. The tropical SST warming is the main cause for the GW impact on Sahel rainfall. Regarding the AMO, the pattern of anomalous precipitation is established by the SSTs in the Atlantic and Mediterranean basins. In turn, the tropical SST anomalies control the impact of the IPO component on West Africa. Our results suggest that the low-frequency evolution of Sahel rainfall can be interpreted as the competition of three factors: the effect of the GW, the AMO and the IPO. Following this interpretation, our results show that 50% of the SST-driven Sahel drought in the 1980s is explained by the change to a negative phase of the AMO, and that the GW contribution was 10%. In addition, the partial recovery of Sahel rainfall in recent years was mainly driven by the AMO.

  20. Fine-scale temperature variability: The influence of near-inertial waves

    NASA Astrophysics Data System (ADS)

    Marmorino, G. O.; Rosenblum, L. J.; Trump, C. L.

    1987-11-01

    Measurements made with a towed thermistor chain and acoustic doppler current profiler in the seasonal thermocline of the Sargasso Sea are examined for relationships among small-scale temperature "activity," shear, and internal wave variability. Patches of intense activity measuring 5-10 m high and several kilometers in length are found to persist within a near-inertial wave packet. The packet was tagged with a drogue and followed for about 16 hours as it was advected along an edge of a cold-core ring. The patches occur along surfaces of high vertical shear, where the Richardson number (7-m vertical resolution) falls to values less than one. Within the patches are groups of small-scale internal waves and fluid overturns. The overturns are 1-3 m high and are associated with wave-breaking events. Away from the wave packet, activity levels are less, and the active fraction of the water column appears to be linked to variability in the internal wave field. It is conjectured that the near-inertial wave patches are the same species as persistent mixing patches observed by Gregg et al. (1986), which were also associated with a near-inertial wave.

  1. Tropospheric temperature gradient and its relation to the South and East Asian precipitation variability

    NASA Astrophysics Data System (ADS)

    Vaid, B. H.; San Liang, X.

    2015-05-01

    Using the NCEP-DOE AMIP-2 daily reanalysis data sets, the tropospheric temperature (TT) changes over East Asia for the period 1988-2010 are analyzed. It is found that on the layer-averaged TT between 1000 and 400 mb, there exist two centers, one sitting over Mongolia, another over Tibet. An index, called TT index, is defined as the difference between the TT over these centers. The TT index is observed to reflect the circulation anomaly through thermal wind relation. A significant increase in magnitude is identified after 1999; the trend, however, reveals a much milder slope in comparison to that prior to 1999. It is found that the TT index is highly correlated to the South and East Asian precipitation variability. It is related to other monsoon indices in that it takes a lead of approximately 15 days; computation with a newly developed rigorous causality analysis reveals unambiguously a one-way causality from the TT index to the latter. That is to say, we could have identified something that may help better predict the precipitation variability.

  2. Orbital-scale summer precipitation and temperature variability in central China reconstructed with leaf wax hydrogen isotopes and branched GDGTs

    NASA Astrophysics Data System (ADS)

    Thomas, E. K.; Clemens, S. C.; Prell, W. L.; Sun, Y.; Huang, Y.

    2013-12-01

    Reconstructions of monsoon variability on orbital time scales inform how the monsoon responds to large variations in forcing mechanisms (e.g., insolation, ice volume, greenhouse gases). The timing, or phase, of proxy response relative to forcing mechanisms (e.g., maximum insolation, maximum ice volume) can provide insights into which mechanisms control monsoon variability. Furthermore, obtaining summer monsoon records from different regions of Asia provides information about the spatial expression of monsoon variability. Deciphering which mechanisms control orbital-scale summer monsoon variability, however, requires reconstructions using proxies that respond mainly to summer monsoon variability. We present a 300-kyr-long, millennial-resolution record of Pleistocene summer monsoon precipitation variability on the Chinese Loess Plateau, generated using leaf wax hydrogen isotopes. The loess plateau receives ca. 50% of total annual precipitation during the summer monsoon, and plants produce leaf waxes during the warm, wet summer months. Thus, leaf wax hydrogen isotopes reflect summer precipitation isotopes. Precipitation isotopes change in response to changes in transport history (e.g. source water isotope ratios, transport path, etc.), which is influenced by changes in monsoon strength. Precipitation isotopes are also affected by local condensation temperature, which we account for using an independent temperature proxy, branched glycerol dialkyl glycerol tetraethers. We present these independent monsoon and temperature records and examine implications for mechanisms controlling monsoon variability in central China.

  3. Decadal slowdown in global air temperature rise triggered by variability in the Atlantic Meridional Overturning Circulation

    NASA Astrophysics Data System (ADS)

    England, Matthew H.

    2015-04-01

    Various explanations have been proposed for the recent slowdown in global surface air temperature (SAT) rise, either involving enhanced ocean heat uptake or reduced radiation reaching Earth's surface. Among the mechanisms postulated involving enhanced ocean heat uptake, past work has argued for both a Pacific and Atlantic origin, with additional contributions from the Southern Ocean. Here we examine the mechanisms driving 'hiatus' periods originating out of the Atlantic Ocean. We show that while Atlantic-driven hiatuses are entirely plausible and consistent with known climate feedbacks associated with variability in the Atlantic Meridional Overturning Circulation (AMOC), the present climate state is configured to enhance global-average SAT, not reduce it. We show that Atlantic hiatuses are instead characterised by anomalously cool fresh oceanic conditions in the North Atlantic, with the atmosphere advecting the cool temperature signature zonally. Compared to the 1980s and 1990s, however, the mean climate since 2001 has been characterised by a warm saline North Atlantic, suggesting the AMOC cannot be implicated as a direct driver of the current hiatus. We further discuss the impacts of a warm tropical Atlantic on the unprecedented trade wind acceleration in the Pacific Ocean, and propose that this is the main way that the Atlantic has contributed to the present "false pause" in global warming.

  4. Variability of Surface Temperature and Melt on the Greenland Ice Sheet, 2000-2011

    NASA Technical Reports Server (NTRS)

    Hall, Dorothy K.; Comiso, Josefino, C.; Shuman, Christopher A.; Koenig, Lora S.; DiGirolamo, Nicolo E.

    2012-01-01

    Enhanced melting along with surface-temperature increases measured using infrared satellite data, have been documented for the Greenland Ice Sheet. Recently we developed a climate-quality data record of ice-surface temperature (IST) of the Greenland Ice Sheet using the Moderate-Resolution Imaging Spectroradiometer (MODIS) 1ST product -- http://modis-snow-ice.gsfc.nasa.gov. Using daily and mean monthly MODIS 1ST maps from the data record we show maximum extent of melt for the ice sheet and its six major drainage basins for a 12-year period extending from March of 2000 through December of 2011. The duration of the melt season on the ice sheet varies in different drainage basins with some basins melting progressively earlier over the study period. Some (but not all) of the basins also show a progressively-longer duration of melt. The short time of the study period (approximately 12 years) precludes an evaluation of statistically-significant trends. However the dataset provides valuable information on natural variability of IST, and on the ability of the MODIS instrument to capture changes in IST and melt conditions indifferent drainage basins of the ice sheet.

  5. Spatial and temporal variability of soil temperature, moisture and surface soil properties

    NASA Technical Reports Server (NTRS)

    Hajek, B. F.; Dane, J. H.

    1993-01-01

    The overall objectives of this research were to: (l) Relate in-situ measured soil-water content and temperature profiles to remotely sensed surface soil-water and temperature conditions; to model simultaneous heat and water movement for spatially and temporally changing soil conditions; (2) Determine the spatial and temporal variability of surface soil properties affecting emissivity, reflectance, and material and energy flux across the soil surface. This will include physical, chemical, and mineralogical characteristics of primary soil components and aggregate systems; and (3) Develop surface soil classes of naturally occurring and distributed soil property assemblages and group classes to be tested with respect to water content, emissivity and reflectivity. This document is a report of studies conducted during the period funded by NASA grants. The project was designed to be conducted over a five year period. Since funding was discontinued after three years, some of the research started was not completed. Additional publications are planned whenever funding can be obtained to finalize data analysis for both the arid and humid locations.

  6. Vital role of daily temperature variability in surface mass balance parameterizations of the Greenland Ice Sheet

    NASA Astrophysics Data System (ADS)

    Rogozhina, I.; Rau, D.

    2014-04-01

    This study aims to demonstrate that the spatial and seasonal effects of daily temperature variability in positive degree-day (PDD) models play a decisive role in shaping the modeled surface mass balance (SMB) of continental-scale ice masses. Here we derive monthly fields of daily temperature standard deviation (SD) across Greenland from the ERA-40 (European Centre for Medium-Range Weather Forecasts 40 yr Reanalysis) reanalysis spanning from 1958 to 2001 and apply these fields to model recent surface responses of the Greenland Ice Sheet (GIS). Neither the climate data set analyzed nor in situ measurements taken in Greenland support the range of commonly used spatially and temporally uniform SD values (~ 5 °C). In this region, the SD distribution is highly inhomogeneous and characterized by low values during summer months (~ 1 to 2.5 °C) in areas where most surface melting occurs. As a result, existing SMB parameterizations using uniform, high SD values fail to capture both the spatial pattern and amplitude of the observed surface responses of the GIS. Using realistic SD values enables significant improvements in the modeled regional and total SMB with respect to existing estimates from recent satellite observations and the results of a high-resolution regional model. In addition, this resolves large uncertainties associated with other major parameters of a PDD model, namely degree-day factors. The model appears to be nearly insensitive to the choice of degree-day factors after adopting the realistic SD distribution.

  7. Second law analysis of advanced power generation systems using variable temperature heat sources

    SciTech Connect

    Bliem, C.J.; Mines, G.L.

    1990-01-01

    Many systems produce power using variable temperature (sensible) heat sources. The Heat Cycle Research Program is currently investigating the potential improvements to such power cycles utilizing moderate temperature geothermal resources to produce electrical power. It has been shown that mixtures of saturated hydrocarbons (alkanes) or halogenated hydrocarbons operating with a supercritical Rankine cycle gave improved performance over boiling Rankine cycles with the pure working fluids for typical applications. Recently, in addition to the supercritical Rankine Cycle, other types of cycles have been proposed for binary geothermal service. This paper explores the limits on efficiency of a feasible plant and discusses the methods used in these advanced concept plants to achieve the maximum possible efficiency. The advanced plants considered appear to be approaching the feasible limit of performance so that the designer must weigh all considerations to fine the best plant for a given service. These results would apply to power systems in other services as well as to geothermal power plants. 17 refs., 15 figs.

  8. Sahel rainfall and decadal to multi-decadal sea surface temperature variability

    NASA Astrophysics Data System (ADS)

    Mohino, Elsa; Janicot, Serge; Bader, Juergen

    2010-05-01

    Sahel rainfall variability at decadal time-scales has been mainly driven by Sea Surface Temperatures (SSTs) in the 20th century. During that period, SSTs have shown a marked long-term trend of global warming (GW) that was externally forced by natural and anthropogenic sources. Superimposed on this long-term trend, patterns of decadal variability have been observed. Centred in the North Atlantic, the Atlantic Multidecadal Oscillation (AMO) is a pattern of variation related to the oceanic thermohaline circulation. The Pacific basin also hosts a pattern of oscillation at decadal time-scales called the Interdecadal Pacific Oscillation (IPO). In this work we investigated the relative contribution of each component to Sahel precipitation variability at decadal time-scales. For the sake of completeness, we also analysed the contribution of Indian decadal variability (IDV). For this aim we used simulations forced by idealized patterns of world-wide SST anomalies representative of these components. The simulations show that all four SST signals have a significant impact over West African Monsoon: the positive phases of GW, IPO and IDV lead to drought over the Sahel, while a positive AMO enhances Sahel rainfall. Our simulations also show that tropical warming of SST is the main cause for the GW impact on Sahel. Regarding AMO, the pattern of anomalous precipitation is established by the SSTs in the Atlantic and Mediterranean basins. Conversely, the Pacific basin alone can not account for the IPO effect over WAM. In turn, the tropical SSTs control the IDV impact on WAM. Though GW, AMO and IPO signals are highly unrelated among them, IDV is found to be mostly explained by AMO and IPO global signals. Our results suggest that decadal evolution of Sahel rainfall can be interpreted as the competition of three factors: the effect of GW, AMO and IPO. Following this interpretation, our results show that 40 to 50% of Sahel drought in the 1980s is explained by the change to a negative phase of the AMO, and that GW contributed between 10 and 30%. In addition, the partial recovery of Sahel rainfall in recent years was mainly driven by the AMO.

  9. Understanding convection features over Bay of Bengal using sea surface temperature and atmospheric variables

    NASA Astrophysics Data System (ADS)

    Uma, R.; Lakshmi Kumar, T. V.; Narayanan, M. S.

    2015-06-01

    Tropical oceanic regions are frequently prone to deep convections. Hence, it is very essential to understand the features of convection with the help of oceanic and atmospheric variables such as sea surface temperature (SST), outgoing longwave radiation (OLR), rainfall, relative humidity, columnar water vapour (CWV) etc. and the linkage among them. In our present study, we have divided the Bay of Bengal (BoB) into ten different subregions (SR) and have attempted to study the connection between the above-stated variables during convective and non-convective events in the southwest monsoon (SWM) season (June to September) for the period 1998-2010. The monthly behaviour of SST/OLR decreased by 0.5 °C/14 W/m2 from May to June and increased by 0.1 °C/7 W/m2 from September to October. Among the ten SRs, SR 5 and SR 10 are observed to be coldest and warmest, respectively, based on the SST variations. Intra-seasonal oscillations of the above-mentioned variables show the influences of quasi-biweekly oscillations (QBWO) and Madden-Julian oscillations (MJO). As the threshold values for SST, OLR and rainfall were already reported, we have drawn our attention to deduce a threshold value for water vapour in lower level troposphere (water vapour density (WVD) at 850 mb) which highly influences the convection. In arriving at a threshold of low-level water vapour, we have analysed the convective and non-convective events of each central 1 × 1° grid in all the SRs for the period from 1998 to 2010, along with water vapour scale height. Our analysis inferred that the low-level water vapour density at 850 mb varied above 12 g/m3during convective days and below 12 g/m3during non-convective days. We noticed that the variability in water vapour density is more in non-convective days than in convective days over BoB. The results of the study may be useful to understand the water vapour dynamics with SST, OLR and rainfall.

  10. Ground and surface temperature variability for remote sensing of soil moisture in a heterogeneous landscape

    USGS Publications Warehouse

    Giraldo, M.A.; Bosch, D.; Madden, M.; Usery, L.; Finn, M.

    2009-01-01

    At the Little River Watershed (LRW) heterogeneous landscape near Tifton Georgia US an in situ network of stations operated by the US Department of Agriculture-Agriculture Research Service-Southeast Watershed Research Lab (USDA-ARS-SEWRL) was established in 2003 for the long term study of climatic and soil biophysical processes. To develop an accurate interpolation of the in situ readings that can be used to produce distributed representations of soil moisture (SM) and energy balances at the landscape scale for remote sensing studies, we studied (1) the temporal and spatial variations of ground temperature (GT) and infra red temperature (IRT) within 30 by 30 m plots around selected network stations; (2) the relationship between the readings from the eight 30 by 30 m plots and the point reading of the network stations for the variables SM, GT and IRT; and (3) the spatial and temporal variation of GT and IRT within agriculture landuses: grass, orchard, peanuts, cotton and bare soil in the surrounding landscape. The results showed high correlations between the station readings and the adjacent 30 by 30 m plot average value for SM; high seasonal independent variation in the GT and IRT behavior among the eight 30 by 30 m plots; and site specific, in-field homogeneity in each 30 by 30 m plot. We found statistical differences in the GT and IRT between the different landuses as well as high correlations between GT and IRT regardless of the landuse. Greater standard deviations for IRT than for GT (in the range of 2-4) were found within the 30 by 30 m, suggesting that when a single point reading for this variable is selected for the validation of either remote sensing data or water-energy models, errors may occur. The results confirmed that in this landscape homogeneous 30 by 30 m plots can be used as landscape spatial units for soil moisture and ground temperature studies. Under this landscape conditions small plots can account for local expressions of environmental processes, decreasing the errors and uncertainties in remote sensing estimates caused by landscape heterogeneity.

  11. Variability of Sea Surface Temperature Response to Tropical Cyclones along the NEC Bifurcation Latitude

    NASA Astrophysics Data System (ADS)

    Fernandez, I.; Villanoy, C. L.

    2013-12-01

    The east of the Philippines serves as an entry point to an annual average of 20 tropical cyclones. The ocean is dynamic where the North Equatorial Current (NEC) bifurcates into the Kurushio Current to the north and Mindanao Current to the south. The displacement and intensity of NEC bifurcation in the region varies seasonally and interannually driven by local monsoons and ENSO. The variability of the NEC bifurcation latitude may alter the origins of the Kuroshio and modify the sea surface temperature field, which can alter the strength of the typhoons and upper ocean response. This paper aims to characterize the variability of Sea Surface Temperature (SST) Response to Tropical Cyclones along with the NEC Bifurcation latitude using daily merged product of the TRMM Microwave Imager (TMI) and Advanced Microwave Scanning Radiometer (AMSR-E), Sea Surface Height (SSH) and SSH Anomaly (SSHA) from AVISO and background climatological D26 (depth of 26 °C) and T100 (depth integrated temperature up to 100 meters) from ARGO profiles and CTD data from WOA09 from 2003 to 2012. SSH measurements from this period were used as a proxy for determining the bifurcation latitude (YB). Characteristics of the meridional distribution from 0° to 30°N of D26 is homogenous along 10-15°N. Monthly mean D26 along 10-15°N, 125-145°E shows high correlation with YB . Variations of the D26 and T100 showed deepening and warming along with YB. Two regions were derived from meridional distribution of T100 namely BSouth (<15°N) where background climatological condition is warm all throughout the year with deep D26 and BNorth (>15°N), where background climatological condition is shallow (D26) and varies seasonally. These regions where used to compare variability with respect to SST recovery time and the SST maximum change (?SSTmax) along with other factors such as TCs translation speed (TS) and intensity based on the Saffir-Simpson Hurricane Scale. Results showed that in both regions SST Recovery time is described as fast (<= 5day) when ?SSTmax is less than 1°C. Also, slow-moving TCs (TS < 4 m/s) is associated with maximum change in temperature and most often with longer Recovery time (>5days). Difference between both regions can be described with respect to the ?SSTmax. Higher ?SSTmax of up to 7°C was observed on BNorth which can be attributed to colder water (Temp < 26) brought up to surface given a shallow D26 layer. Moreover, the presence of cold-core eddies (SSHA <0) contributes to higher maximum cooling on the region. On the other hand, ?SSTmax is up to 4°C in BSouth associated with deeper D26 of >= 100m allowing only warm water (Temp>26) to be brought to the surface.

  12. [Tuberculosis in day-to-day medical practice and the boomerang effect of neglect].

    PubMed

    Selig, Lia; Geluda, Kátia; Junqueira, Túlio; Brito, Rossana; Trajman, Anete

    2012-01-01

    The scope of this study was to understand the perceptions and feelings of physicians dealing with tuberculosis (TB) in Rio de Janeiro. Eleven physicians working in a large public hospital were interviewed using a semi-structured questionnaire. The interpretation of the interviews was based on hermeneutic-dialectic phenomenology. The answers were analyzed in order to identify and understand their live TB-related experiences from their statements. Among the categories that emerged, neglect was chosen as the focus of this article in its four dimensions: respect, responsibility, conditions of care and discomfort. The boomerang effect of neglect was perceived during interviews with physicians: the one who neglects is also neglected. Other reported feelings included lack of motivation, anger, and frustration. The mental health of physicians is a preoccupation because of overwork in inadequate conditions. The question that arises is how health staff working in such environments can adequately care for their patients. We conclude that in order to achieve TB control as well as other health system goals, human resource policies that respond to physicians' job needs should be implemented. PMID:22218545

  13. [The two sides of the coin: the day-to-day aspect of bipolar disorder].

    PubMed

    Carvalho, Mauro Filipe Peixe

    2008-01-01

    The bipolar affective illness is a serious psychiatric disorder, which presents high rate of relapse and apparent functional damage (AZEVEDO, 1998). Because of their impact on society and society in patients, sometimes with drastic consequences, I prepared this article which aims to clarify what is the bipolar disorder, identify her clinical symptoms and treatment and the nursing care that these patients need. There is a great need for knowledge about this disease, so that the general public understands the implications of living this way. There is then a need to integrate the mentally ill into society and the development of techniques that facilitate integration. The nurses, as professionals in the first line of care, have a decisive role in the interaction with these patients, not only in terms of treatment, but mainly in the social integration process of these individuals. PMID:18751610

  14. Clinical Implications of the CATIE Schizophrenia Trials: Day-to-Day Management Lessons for Australasian Psychiatrists

    Microsoft Academic Search

    Peter Bick; Natalie Knoesen; David Castle

    2007-01-01

    Objective: The aim of this paper was to review whether the $50m spent by the US National Institute of Mental Health in doing the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) trials found any useful evidence to change the clinical management of schizophrenia by psychiatrists.Conclusions: The CATIE trials were conducted in the US on 1460 enrolled patients in an effort

  15. “Living from Day to Day”: Food Insecurity, Complexity, and Coping in Mutare, Zimbabwe

    Microsoft Academic Search

    Pauline Gwatirisa; Lenore Manderson

    2012-01-01

    In Zimbabwe, unpredictable conditions associated with structural and institutional factors exacerbated the combined effects of structural violence, economic and political instability, and climate change in the mid 2000s, contributing to widespread food insecurity. Drought, food shortages, and government settlement policy affecting both rural and urban populations has yielded a national human rights crisis. Drawing on ethnographic research conducted in Mutare,

  16. Discontinuous daily temperatures in the WATCH forcing data sets

    NASA Astrophysics Data System (ADS)

    Rust, Henning; Kruschke, Tim; Dobler, Andreas; Fischer, Madlen; Ulbrich, Uwe

    2015-04-01

    The WATCH forcing data sets have been created to support the use of hydrological and land surface models for the assessment of the water cycle within climate change studies. They are based on ECMWF reanalysis products (ERA-40 or ERA-Interim) with temperature (among other variables) adjusted such that their monthly means match the monthly temperature data set from the Climatic Research Unit. To this end, daily minimum, maximum and mean temperatures within one calendar month have been subjected to a correction involving monthly means of the respective month. As these corrections can be largely different for adjacent months this procedure is potentially leading to unplausible differences in daily temperatures across the boundaries of calendar months. We analyze day-to-day temperature fluctuations within and across months and find that across months differences are significantly larger, mostly in the tropics and frigid zones. Average across-months differences in daily mean temperature are typically between 10% to 40% larger than their corresponding average within-months temperature differences. However, regions with differences up to 200% can be found in the tropical Africa. Daily maximum and minimum temperatures are affected in the same regions but in a less sever way.

  17. Short-term temperature variability in the Rose Garden hydrothermal vent field: an unstable deep-sea environment

    NASA Astrophysics Data System (ADS)

    Johnson, Kenneth S.; Childress, James J.; Beehler, Carl L.

    1988-10-01

    Temperature was measured within the animal communities of the Rose Garden hydrothermal vent field with three thermistors that were left in place for a period of 72 h. The highest mean temperature (5.54°C) was measured at a thermistor placed in the central clump of vestimentiferan worms, while the lowest mean value (2.26°C) was recorded over the basaltic substrate. The temperature of the ambient water in the field was 2.07°C. The site with the highest temperature was characterized by extreme variability in the temperature, with minimum values of 2.16°C and maximum values of 14.81°C. The temperature fluctuated over all of the time scales studied from 1 s to 72 h. There was no clear periodicity to the temperature fluctuations, however. These temperature fluctuations must have significant impacts on adaptations, by the animals of the vent community. In fact, the variability in temperature may be more important to the community than the mean temperature value to which they are exposed.

  18. Nature of the Mesoscale Boundary Layer Height and Water Vapor Variability Observed 14 June 2002 during the IHOP_2002 Campaign

    E-print Network

    Guichard, Francoise

    Nature of the Mesoscale Boundary Layer Height and Water Vapor Variability Observed 14 June 2002, Boulder, Colorado (Manuscript received 4 September 2007, in final form 23 June 2008) ABSTRACT Mesoscale at the mesoscale, with the spatial pattern and the magnitude of the variability changing from day to day. On 14

  19. Satellite Observed Variability in Antarctic and Arctic Surface Temperatures and Their Correlation to Open Water Areas

    NASA Technical Reports Server (NTRS)

    Comiso, Josefino C.; Zukor, Dorothy (Technical Monitor)

    2000-01-01

    Recent studies using meterological station data have indicated that global surface air temperature has been increasing at a rate of 0.05 K/decade. Using the same set of data but for stations in the Antarctic and Arctic regions (>50 N) only, the increases in temperature were 0.08, and 0.22 K/decade, when record lengths of 100 and 50 years, respectively, were used. To gain insights into the increasing rate of warming, satellite infrared and passive microwave observations over the Arctic region during the last 20 years were processed and analyzed. The results show that during this period, the ice extent in the Antarctic has been increasing at the rate of 1.2% per decade while the surface temperature has been decreasing at about 0.08 K per decade. Conversely, in the Northern Hemisphere, the ice extent has been decreasing at a rate of 2.8% per decade, while the surface temperatures have been increasing at the rate of 0.38 K per decade. In the Antarctic, it is surprising that there is a short term trend of cooling during a global period of warming. Very large anomalies in open water areas in the Arctic were observed especially in the western region, that includes the Beaufort Sea, where the observed open water area was about 1x10(exp 6) sq km, about twice the average for the region, during the summer of 1998. In the eastern region, that includes the Laptev Sea, the area of open water was also abnormally large in the summer of 1995. Note that globally, the warmest and second warmest years in this century, were 1998 and 1995, respectively. The data, however, show large spatial variability with the open water area distribution showing a cyclic periodicity of about ten years, which is akin to the North Atlantic and Arctic Oscillations. This was observed in both western and eastern regions but with the phase of one lagging the other by about two years. This makes it difficult to interpret what the trends really mean. But although the record length of satellite data is still relatively short and the climate trend difficult to establish, the immediate impact of a continued warming trend may be very profound.

  20. Diurnal variability of total ozone column over Madrid (Spain)

    Microsoft Academic Search

    M. Antón; M. López; A. Serrano; M. Bañón; J. A. García

    2010-01-01

    In recent years, research on ozone variability has mainly focused on the analysis of its trend. Additionally some studies have analyzed the annual, seasonal and day-to-day ozone variations. However, intra-diurnal total ozone variations are notably less explored. Thus, the main objective of this paper is to analyze the diurnal variability of total ozone column (TOC) as recorded by a Brewer

  1. Southern High Latitude Climate and Internal Variability Influence on Eastern Equatorial Pacific Thermostad Temperatures during the Holocene

    NASA Astrophysics Data System (ADS)

    Kalansky, J.; Rosenthal, Y.; Herbert, T.

    2014-12-01

    Subantarctic Mode Water (SAMW) plays a critical role in transporting heat, nutrients and CO2 from the Southern Ocean to the base of the equatorial thermocline in the eastern equatorial Pacific (EEP). In turn, the heat and nutrients storage below the thermocline (~100-500 m) in the EEP can exert large effect on Earth's climate through ocean-atmosphere heat and CO2 exchange. Here we present a centennially resolved Holocene subsurface temperature reconstruction using Mg/Ca of Neogloboquadrina dutertrei from the eastern equatorial Pacific (EEP). In the EEP N. dutertrei calcifies at about ~125 m which is below the Equatorial Undercurrent and the upper limit of the thermostad water in this region. During the early Holocene N. dutertrei temperatures vary between 14.5?C and 16.5?C, whereas by 8 kyr B.P. the temperature drops to 13?C. The cooling by 8 kyr is also observed in the bottom water (~400 m) temperature reconstructions from Uvigerina spp. The early Holocene cooling of the thermostad water is likely linked to southern high latitude climate variability attributed to changes in the southern westerly winds (SWW). We posit that a more southern position of the SWW in the early Holocene increased the influence of warm subtropical water into the formation region of and thereby warming SAMW. Additionally, a southward position of the SWW increased SAMW production causing the southern high latitude signal to reach farther into the EEP. After 8 ky, thermostad temperatures show millennial and centennial variability, with low temperature between 4.8-3.6 kyr followed by high temperatures during the next 500 years. High resolution record of the last 2,000 years also show multidecadal to multicentennial thermostad temperature variability. The timing of this variability does not follow the Northern Hemisphere temperature variability including the Little Ice Age and Medieval Climate Anomaly. We conclude that in absence of a strong climate signal from the southern high latitudes during the mid to late Holocene the centennial variability in the EEP hydrography is dominated by intrinsic variability.

  2. Variability and Predictability of the Surface Temperature Field on a Zonally Symmetric Land Planet

    NASA Astrophysics Data System (ADS)

    Leung, Lai-Yung

    An information approach to the study of climate predictability is introduced. This approach uses various information measures based on entropy to define the limits of predictability and to quantify the information given by different climate components and boundary forcings about the prediction of future climate anomalies. Together with a set of basis functions defined through frequency dependent empirical orthogonal functions, this method provides a systematic way of studying the regional predictability of a complex system. The method is applied to study predictability of the atmosphere simulated by the NCAR CCMO on a zonally symmetric land planet. By removing the ocean in the simulation, the time scale of the system has been greatly reduced. Hence, this simulation provides sufficient time samples for realistic study of the properties of the atmospheric component. Atmospheric variability as simulated under the various idealized boundary conditions is studied. This provides noise climatologies useful for climate sensitivity experiments. The space-time statistics of the simulated surface temperature field are fitted satisfactorily by a stochastic climate model with only five parameters. This suggests the usefulness of simple statistical models as guidance for climate sensitivity studies, and sampling considerations for model simulation or data collection. The limit of predictability of the first kind of the surface temperature field is found over two zonal bands: tropics (0^circ-20^ circ) and mid-latitudes (40^ circ-60^circ). The predictability as a function of spherical harmonic degree is also evaluated. Results are consistent with past studies of atmospheric predictability using random perturbation experiments. Extension of the above study to climate predictability of the second kind is discussed.

  3. Mixing times towards demographic equilibrium in insect populations with temperature variable age structures.

    PubMed

    Damos, Petros

    2015-08-01

    In this study, we use entropy related mixing rate modules to measure the effects of temperature on insect population stability and demographic breakdown. The uncertainty in the age of the mother of a randomly chosen newborn, and how it is moved after a finite act of time steps, is modeled using a stochastic transformation of the Leslie matrix. Age classes are represented as a cycle graph and its transitions towards the stable age distribution are brought forth as an exact Markov chain. The dynamics of divergence, from a non equilibrium state towards equilibrium, are evaluated using the Kolmogorov-Sinai entropy. Moreover, Kullback-Leibler distance is applied as information-theoretic measure to estimate exact mixing times of age transitions probabilities towards equilibrium. Using empirically data, we show that on the initial conditions and simulated projection's trough time, that population entropy can effectively be applied to detect demographic variability towards equilibrium under different temperature conditions. Changes in entropy are correlated with the fluctuations of the insect population decay rates (i.e. demographic stability towards equilibrium). Moreover, shorter mixing times are directly linked to lower entropy rates and vice versa. This may be linked to the properties of the insect model system, which in contrast to warm blooded animals has the ability to greatly change its metabolic and demographic rates. Moreover, population entropy and the related distance measures that are applied, provide a means to measure these rates. The current results and model projections provide clear biological evidence why dynamic population entropy may be useful to measure population stability. PMID:26025884

  4. Observed and model simulated 20th century Arctic temperature variability: Canadian Earth System Model CanESM2

    Microsoft Academic Search

    P. Chylek; J. Li; M. K. Dubey; M. Wang; G. Lesins

    2011-01-01

    We present simulations of the 20th century Arctic temperature anomaly from the second generation Canadian Earth System Model (CanESM2). The new model couples together an atmosphere-ocean general circulation model, a land-vegetation model and terrestrial and oceanic interactive carbon cycle. It simulates well the observed 20th century Arctic temperature variability that includes the early and late 20th century warming periods and

  5. Cycles and shifts: 1,300 years of multi-decadal temperature variability in the Gulf of Alaska

    Microsoft Academic Search

    Rob Wilson; Greg Wiles; Rosanne D'Arrigo; Chris Zweck

    2006-01-01

    The Gulf of Alaska (GOA) is highly sensi- tive to shifts in North Pacific climate variability. Here we present an extended tree-ring record of January- September GOA coastal surface air temperatures using tree-ring width data from coniferous trees growing in the mountain ranges along the GOA. The reconstruction (1514-1999), based on living trees, ex- plains 44% of the temperature variance,

  6. Decoupled control of temperature and relative humidity using a variable-air-volume HVAC system and non-interacting control

    Microsoft Academic Search

    C. Rentel-Gomez; M. Velez-Reyes

    2001-01-01

    In this paper, we develop a nonlinear noninteracting control system for temperature and relative humidity in a thermal-space conditioned by a variable-air-volume (VAV) heating, ventilating, and air conditioning (HVAC) system. In some industrial processes it is desirable to be able to control temperature and relative humidity independently and accurately. When the controller does not take into account the coupling dynamics

  7. Spatial variability in subsurface warming over the last three decades; insight from repeated borehole temperature measurements in The Netherlands

    NASA Astrophysics Data System (ADS)

    Kooi, Henk

    2008-06-01

    Subsurface temperatures around the world are changing in response to accelerated surface atmospheric temperature (SAT) rise, but are also impacted by other natural and anthropogenic changes in surface environmental conditions which alter the surface energy balance. Improved understanding of the latter influences is important for geothermal climate applications and to generate a comprehensive knowledge-framework of subsurface warming, including inherent spatial variability. Here I examine sixteen wells in a relatively small area in The Netherlands, each with two available temperature logs recorded some three decades apart. Temperature differences of the log pairs reveal marked differences in subsurface warming amongst the wells for this time period. Forward modelling of the observed temperature changes, using surface air temperature (SAT) forcing, shows that a considerable part of this inter-site variability may be caused by inter-site differences in thermal properties and groundwater flow conditions. However, for some of the wells these factors are insufficient, implying contributions from non-SAT-driven changes in ground surface temperature (GST). In one case an anomalous decrease in GST can be linked to back-growth of the canopy after forest cutting. For another well site, GST warming has been less than SAT warming in the absence of apparent changes in surface conditions, indicating local, subtle influences on the surface energy balance independent of SAT. The results demonstrate that repeated borehole temperature logging resolves key uncertainties and ambiguities pertaining to interpretation of individual temperature logs. The study further highlights the importance of establishing high-quality borehole temperature databases, also for these relatively complex settings with dynamic and variable surface conditions.

  8. Near-surface current and temperature variability observed in the equatorial Atlantic from drifting buoys

    NASA Astrophysics Data System (ADS)

    Reverdin, G.; McPhaden, M. J.

    1986-05-01

    We examine data from 23 surface drifters which were deployed between June 1983 and July 1984 at 4°W, 1.5°-4°S. The drifters were equipped with a window shade drogue centered at 15-m depth and in most cases a 117-m-long thermistor chain. Drift data indicate a westward South Equatorial Current with typical speeds of about 20 cm s-1 south of the equator. Maximum westward flow of 30-40 cm s-1 occurred in June through September of 1983 and 1984, consistent with climatology. Near-zero westward flow, which was significantly weaker than was expected from climatology (by about 20 cm s-1), occurred from February to April, 1984. This probably represents real interannual variability and may be related to the fact that the equatorial Atlantic was warmer than usual in the spring and summer of 1984. Energetic variations on time scales of O(1 month) and less and space scales of O(100 km) and less are ubiquitous in the drift and temperature data. Kinetic energy levels associated with these variations south of the equator are typically 100 cm2 s-2, with slightly higher values in boreal summer. Energy levels north of the equator are about 500 cm2 s-2 on the basis of data available only during the boreal summer and fall. The sources of this energy include inertia-gravity waves, instabilities of the general circulation, and other phenomena for which there is no simple explanation.

  9. Time Variability of the Global Temperature Distribution of Mimas and Janus

    NASA Astrophysics Data System (ADS)

    Tu, L.; Ip, W.

    2013-12-01

    Strong surface interaction of the inner Saturnian moon, Mimas, with energetic ions and MeV electrons has led to space weathering effect illustrated by albedo/color asymmetry and variation of the thermal inertia (I) between the leading and trailing hemisphere. The I value in a localized region of the leading hemisphere is about 67×30 J m^(-2) K^(-1) s^(1/2), while the corresponding value in the neighboring area is I<16 J m^(-2) K^(-1) s^(1/2) (Howett et al.,2011)[1]. We simulate the diurnal and seasonal variability of Mimas' global temperature distribution and examine the resultant effect on the possible formation of a surface bounded exosphere. Similar consideration is given to Janus which is the innermost icy of Saturn by taking into account its three-dimensional shape configuration. [1] Howett, C.J.A., J.R. Spencer, P. Schenk, R.E. Johnson, C. Paranicas, T.A. Hurford, A. Verbiscer, and M. Segura (2011), A high-amplitude thermal inertia anomaly of probable magnetospheric origin on Saturn's moon Mimas. Icarus, Volume 216, Issue 1, Pages 221-226.

  10. Analysis of trait mean and variability versus temperature in trematode cercariae: is there scope for adaptation to global warming?

    E-print Network

    Poulin, Robert

    Analysis of trait mean and variability versus temperature in trematode cercariae: is there scope evolution Cercariae Climate change Coefficient of variation Infectivity Output Survival a b s t r a c. Firstly, we assessed how the mean number of infective stages (cercariae) emerging from infected snail

  11. Experimental and simulated temperature distribution of an oil-pebble bed thermal energy storage system with a variable heat source

    Microsoft Academic Search

    A. Mawire; M. McPherson

    2009-01-01

    Axial temperature distributions of a thermal energy storage (TES) system under variable electrical heating have been investigated. An electrical hot plate in thermal contact with a hollow copper spiral coil through which the oil flows simulates a solar collector\\/concentrator system. The hot plate heats up the oil which flows through the storage thus charging the TES system at a constant

  12. Rainfall Variability in Equatorial and Southern Africa: Relationships with Sea Surface Temperatures along the Southwestern Coast of Africa

    Microsoft Academic Search

    Sharon E. Nicholson; Dara Entekhabi

    1987-01-01

    This article presents the results of an analysis of sea surface temperature (SST) fluctuations in the upwelling region along the Benguela coat and its relationship to rainfall variability both along the coast and throughout equatorial and southern Africa. The analysis incorporates compositing and time series analysis. Coastal rainfall is markedly enhanced during warm-water years and suppressed during cold-water years. The

  13. Using Variable Temperature Powder X-Ray Diffraction to Determine the Thermal Expansion Coefficient of Solid MgO

    ERIC Educational Resources Information Center

    Corsepius, Nicholas C.; DeVore, Thomas C.; Reisner, Barbara A.; Warnaar, Deborah L.

    2007-01-01

    A laboratory exercise was developed by using variable temperature powder X-ray diffraction (XRD) to determine [alpha] for MgO (periclase)and was tested in the Applied Physical Chemistry and Materials Characterization Laboratories at James Madison University. The experiment which was originally designed to provide undergraduate students with a…

  14. Variable-temperature 13C solid-state NMR study of the molecular structure of honeybee wax and silk.

    PubMed

    Kameda, Tsunenori; Tamada, Yasushi

    2009-01-01

    To elucidate the native-state crystal structure of beeswax from the Japanese bee, Apis cerana japonica, we determined the relationship between temperature and the 13C solid-state nuclear magnetic resonance (NMR) chemical shift of methylene carbon of beeswax, with comparison to n-alkanes and polyethylene in the orthorhombic, monoclinic, or triclinic crystal form. Variable-temperature 13C solid-state NMR observations of n-alkanes and polyethylene revealed that the chemical shifts of methylene carbon in the orthorhombic crystal form increased linearly with increasing temperature, that of the triclinic form decreased, and that of the monoclinic form was unaltered. These relations were compared with results of variable-temperature 13C solid-state NMR observation of beeswax. Results clarified that the two crystal forms comprising the beeswax in the native state are orthorhombic and monoclinic. The variable-temperature 13C solid-state NMR observations were also applied to interpret the differential scanning calorimetry (DSC) curve of beeswax. They were used to clarify the structural changes of beeswax for widely various temperatures. For beeswax secreted by the Japanese bee, the transition from the orthorhombic form to the rotator phase occurred at 36 degrees C, that is from the crystalline to the intermediate state at 45 degrees C. Moreover, the variable-temperature 13C solid-state NMR spectrum of honeybee silk in the native state was observed. Results demonstrated that the secondary structures of honeybee silk proteins in the native state comprised coexisting alpha-helix and beta-sheet conformations and that the amount of alpha-helices was greater. The alpha-helix content of honeybee silk was compared with that of hornet silk produced by Vespa larvae. PMID:19007807

  15. COOL-SEASON GRASS DEVELOPMENT RESPONSE TO ACCUMULATED TEMPERATURE FOLLOWING VARIABLE EXPOSURE TO BELOW-FREEZING TEMPERATURES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In several temperate grass species there is a linear relation between cumulative leaf appearance and accumulated temperature, or growing day degrees (GDD), above 0 °C. It is not known if this response is changed by short-term exposure to temperatures below freezing. Mainstem leaf appearance rate wa...

  16. Variable-temperature solid-state NMR studies of iron(II) and iron(III) complexes

    E-print Network

    Shepard, Patricia Arlene

    1989-01-01

    sequence. CT is the cross-polarization contact time. MH and MC denote the magnetization of the H and C nuclei, respectively. 2. Variable-temperature C CP/MAS spectra for Fe(2-pic)3C12 EtOH 31 Variable-composition C CP/MAS spectra for FexZnl x(2-pic)3C...12'EtOH (x= 0'. , 20:, 30%, 404). . 33 4. Plot of C T as a function of N for the 158 ppm 13 C resonance in the Fe/Zn(2-pic)3C12'EtOH alloys . 41 1, 5. Schematic of v-oxo-bis[octaethylporphineiron(III)]. 46 Variable-temperature C CP/MAS spectra...

  17. Decadal variability of the tropical Atlantic Ocean surface temperature in shipboard measurements and in a Global Ocean-atmosphere model

    SciTech Connect

    Mehta, V.M. [Goddard Space Flight Center, Greenbelt, MD (United States)] [Goddard Space Flight Center, Greenbelt, MD (United States); Delworth, T. [Geophysical Fluid Dynamics Laboratory, Princeton, NJ (United States)] [Geophysical Fluid Dynamics Laboratory, Princeton, NJ (United States)

    1995-02-01

    Numerous analyses of relatively short (25-30 years in length) time series of the observed surface temperature of the tropical Atlantic Ocean have indicated the possible existence of decadal timescale variability. It was decided to search for such variability in 100-yr time series of sea surface temperature (SST) measured aboard ships and available in the recently published Global Ocean Surface Temperature Atlas (GOSTA). Fourier and singular spectrum analyses of the GOSTA SST time series averaged over 11 subregions, each approximately 1 x 10{sup 6}km{sup 2} in area, show that pronounced quasi-oscillatory decadal ({approximately}-20 yr) and multidecadal ({approximately}30-40 yr) timescale variability exists in the GOSTA dataset over the tropical Atlantic. Motivated by the above results, SST variability was investigated in a 200-yr integration of a global model of the coupled oceanic and atmospheric general circulations developed at the geophysical Fluid Dynamics Laboratory (GFDL). The second 100 yr of SST in the coupled model`s tropical Atlantic region were analyzed with a variety of techniques. Analyses of SST time series, averaged over approximately the same subregions as the GOSTA time series, showed that the GFDL SST anomalies also undergo pronounced quasi-oscillatory decadal and multidecadal variability but at somewhat shorter timescales than the GOSTA SST anomalies. Further analyses of the horizontal structures of the decadal timescale variability in the GFDL coupled model showed the existence of two types of variability in general agreement with results of the GOSTA SST time series analyses. One type, characterized by timescales between 8 and 11 yr, has high spatial coherence within each hemisphere but not between the two hemispheres of the tropical Atlantic. A second type, characterized by timescales between 12 and 20 yr, has high spatial coherence between the two hemispheres. 31 refs., 14 figs., 3 tabs.

  18. Patterns in temporal variability of temperature, oxygen and pH along an environmental gradient in a coral reef.

    PubMed

    Guadayol, Òscar; Silbiger, Nyssa J; Donahue, Megan J; Thomas, Florence I M

    2014-01-01

    Spatial and temporal environmental variability are important drivers of ecological processes at all scales. As new tools allow the in situ exploration of individual responses to fluctuations, ecologically meaningful ways of characterizing environmental variability at organism scales are needed. We investigated the fine-scale spatial heterogeneity of high-frequency temporal variability in temperature, dissolved oxygen concentration, and pH experienced by benthic organisms in a shallow coastal coral reef. We used a spatio-temporal sampling design, consisting of 21 short-term time-series located along a reef flat-to-reef slope transect, coupled to a long-term station monitoring water column changes. Spectral analyses revealed sharp gradients in variance decomposed by frequency, as well as differences between physically-driven and biologically-reactive parameters. These results highlight the importance of environmental variance at organismal scales and present a new sampling scheme for exploring this variability in situ. PMID:24416364

  19. Annually resolved seawater temperature variability of the Sub-polar North Atlantic over the last 1000 years

    NASA Astrophysics Data System (ADS)

    Reynolds, David; Scourse, James; Hall, Ian; Nederbragt, Alexandra; Wanamaker, Alan; Halloran, Paul; Butler, Paul; Richardson, Chris; Eiríksson, Jon; Heinemeier, Jan; Luise Knudsen, Karen

    2015-04-01

    The lack of annually-resolved marine climate records spanning the last millennium constrains our understanding of the natural variability of the global climate system. We present a continuous annually-resolved reconstruction of sub-polar (N Iceland) sea water temperatures (SWT) derived from the 18O analyses of carbonate material drilled from the annually resolved growth increments contained in an absolutely dated master Arctica islandica sclerochronology spanning the period 953-2000. The calibrated SWT reconstruction contains a significant cooling trend over the period 953-1891 (0.1oC per century) and a marked warming trend over the period 1891-2000 (2.3oC per century). The underlying natural variability is controlled by solar irradiance changes modulated by volcanic forcing and internal variability. The modern SWT warming is demonstrated to lie outside the range of natural variability of the last 1000 years consistent with an anthropogenic influence.

  20. Spectrophotometric and Calorimetric Studies of Np(V) Complexation with Acetate at Variable Temperatures (T = 283 - 343 K)

    SciTech Connect

    Rao, Linfeng; Tian, Guoxin; Srinivasan, Thandankorai G.; Zanonato, PierLuigi; Di Bernardo, Plinio

    2009-12-21

    Spectrophotometric titrations were performed to identify the Np(V)/acetate complex and determine the equilibrium constants at variable temperatures (T = 283 - 343 K) and at the ionic strength of 1.05 mol {center_dot} kg{sup -1}. The enthalpy of complexation at corresponding temperatures was determined by microcalorimetric titrations. Results show that the complexation of Np(V) with acetate is weak but strengthened as the temperature is increased. The complexation is endothermic and is entropy-driven. The enhancement of the complexation at elevated temperatures is primarily due to the increasingly larger entropy gain when the solvent molecules are released from the highly-ordered solvation spheres of NpO{sub 2}{sup +} and acetate to the bulk solvent where the degree of disorder is higher at higher temperatures.

  1. Intraseasonal variability of the sea surface temperature in the Tropical Atlantic

    NASA Astrophysics Data System (ADS)

    Diakhate, Moussa; Lazar, Alban; de Coetlogon, Gaëlle; Gaye, Amadou; Eymard, Laurence

    2014-05-01

    The sea surface temperature (SST) intraseasonal variability (ISV) and its interaction with the local surface wind in the tropical Atlantic Ocean are investigated using atmospheric observations and reanalyses of the 2000-2009 decade. Largest SST ISV centers are located in frontal areas of the three main tropical upwelling systems: the Eastern equatorial upwelling (east of 20°W), and the Senegal-Mauritania and Angola-Namibia coastal upwellings. The equatorial SST ISV is dominated by tropical instability waves (TIWs) west of 10°W, and a quasi-biweekly oscillation (QBO) further east, from May to August. Along the West-African coast, two adjacent regions of strong SST ISV are found north and south of 15°N. The southern one is most active during November-May and is dominated by 30-90 days periodicity, with SST anomalies mainly generated by stronger-than-normal Trade winds and Azores anticyclone. The northern one corresponds to a SST ISV maximal in June-September, and a dominant periodicity between 3 and 15 days, with SST anomalies driven by coastal surface wind modulations coming from African Easterly Waves. Off the Angola-Namibia coast, the SST ISV is also maximal at two locations: around 11°S all over the year, and near 21°S in November-March, with a dominant periodicity between 20 and 90 days in both regions. The SST anomalies are created by a jet of coastal southeasterlies mainly controlled by the large-scale St Helena anticyclone. The equatorial upwelling appears to be the region with the clearest signal of surface wind adjusting to SST anomalies, while it is more modest in the other two regions of coastal upwelling.

  2. Wind-driven variability in sea surface temperature front distribution in the California Current System

    NASA Astrophysics Data System (ADS)

    Castelao, Renato M.; Wang, Yuntao

    2014-03-01

    Simultaneous satellite-derived observations from 2002 to 2009 are used to quantify the relation between sea surface temperature (SST) fronts and ocean winds in the California Current System (CCS). An edge-detection algorithm is applied to SST observations to generate monthly maps of frontal probabilities. Empirical orthogonal decompositions reveal that the seasonal evolution of fronts in the CCS is strongly related to the seasonal evolution of coastal alongshore wind stress. The seasonal development of SST fronts is remarkably different to the north and to the south of Cape Mendocino, however. While fronts to the north of the cape extend for hundreds of kilometers from the coast peaking during summer and fall, when upwelling winds are stronger off northern California and Oregon, the region to the south of Cape Mendocino is characterized by high frontal activity during spring in a much narrower band close to the coast. Throughout the region, anomalies in the intensity of upwelling-favorable wind stress are followed by anomalies in frontal activity. The width and speed of the widening of the region of high frontal activity are also related to coastal alongshore wind stress. Interannual variability in the timing of the widening of the region of high frontal activity in the lee of Cape Blanco compared to the timing of the spring transition to upwelling-favorable winds may be related to the wind stress curl distribution in the lee of the cape. Stronger upwelling-favorable wind stress curl anomalies lead to early widening of the region of high frontal activity.

  3. Determining the temporal variability in atmospheric temperature profiles measured using radiosondes and assessment of correction factors for different launch schedules

    NASA Astrophysics Data System (ADS)

    Butterfield, D.; Gardiner, T.

    2015-01-01

    Radiosondes provide one of the primary sources of upper troposphere and stratosphere temperature data for numerical weather prediction, the assessment of long-term trends in atmospheric temperature, study of atmospheric processes and provide intercomparison data for other temperature sensors, e.g. satellites. When intercomparing different temperature profiles it is important to include the effect of temporal mismatch between the measurements. To help quantify this uncertainty the atmospheric temperature variation through the day needs to be assessed, so that a correction and uncertainty for time difference can be calculated. Temperature data from an intensive radiosonde campaign, at Manus Island in Papua New Guinea, were analysed to calculate the hourly rate of change in temperature at different altitudes and provide recommendations and correction factors for different launch schedules. Using these results, three additional longer term data sets were analysed (Lindenberg 1999 to 2008; Lindenberg 2009 to 2012; and Southern Great Plains 2006 to 2012) to assess the diurnal variability of temperature as a function of altitude, time of day and season of the year. This provides the appropriate estimation of temperature differences for given temporal separation and the uncertainty associated with them. A general observation was that 10 or more repeat measurements would be required to get a standard error of the mean of less than 0.1 K per hour of temporal mismatch.

  4. Geographical pattern in first bloom variability and its relation to temperature sensitivity in the USA and China.

    PubMed

    Wang, Huanjiong; Ge, Quansheng; Dai, Junhu; Tao, Zexing

    2015-08-01

    Advance in spring plant phenology over the last several decades has been found in all continents of the Northern Hemisphere. Compared to the studies detecting phenological trends, the studies investigating the geographical pattern of phenological variability (including mean date and magnitude of variability) are rather limited. In this study, we analyzed spatial pattern of mean date and standard deviation (SD) of first bloom date (FBD) time series (?15 years) for black locust (Robinia pseudoacacia) at 22 stations in China, common lilac (Syringa vulgaris) at 79 stations in the Western US and Chinese lilac (Syringa chinensis) at 45 stations in the Eastern US. Subsequently, the impact of geographical factors (latitude, longitude, and altitude) on the mean date and SD was quantified by using the multiple regression analysis method. Meanwhile, the relationship between FBD variability and temperature sensitivity of FBD was examined. Results showed that the mean FBD highly depended on geographical factors for all the three species. Compared to the mean date, the dependence of SD of FBD time series on geographical factors was weaker. The geographical factors could only explain 13 to 31 % of spatial variance in SD of FBD. The negative regression coefficients of latitude (P?variable at lower latitude. At most of stations, significant and negative correlations between FBD and preseason temperature on interannual scale were found, but the temperature sensitivity varied among different stations. The magnitude of temperature sensitivity decreased with increasing latitude. In general, the locations at lower latitude had earlier and more variable spring phenophase and showed stronger phenological response to climate change than the locations at higher latitude. PMID:25312515

  5. Regional and large-scale influences on seasonal to interdecadal variability in Caribbean surface air temperature in CMIP5 simulations

    NASA Astrophysics Data System (ADS)

    Ryu, Jung-Hee; Hayhoe, Katharine

    2015-07-01

    We evaluate the ability of global climate models participating in phase 5 of the Coupled Model Intercomparison Project (CMIP5) to reproduce observed seasonality and interannual variability of temperature over the Caribbean, and compare these with simulations from atmosphere-only (AMIP5) and previous-generation CMIP3 models. Compared to station and gridded observations, nearly every CMIP5, CMIP3 and AMIP5 simulation tends to reproduce the primary inter-regional features of the Caribbean annual temperature cycle. In most coupled model simulations, however, boreal summer temperature lags observations by about 1 month, with a similar lag in the simulated annual cycle of sea surface temperature (SST), and a systematic cold bias in both climatological annual mean air temperature and SST. There is some improvement from CMIP3 to CMIP5 but the bias is still marked compared to AMIP5 and observations, implying that biases in the annual temperature cycle may originate in the ocean component of the coupled models. This also suggests a tendency for models to over-emphasize the influence of SSTs on near-surface temperature, a bias that may be exacerbated by model tendency to over-estimate ocean mixed layer depth as well. In contrast, we find that both coupled and atmosphere-only models tend to reasonably simulate the response of observed temperature to global temperature, to regional and large-scale variability across the Caribbean region and the Gulf of Mexico, and even to more remote Atlantic and Pacific influences. These findings contribute to building confidence in the ability of coupled models to simulate the effect of global-scale change on the Caribbean.

  6. Large-scale spatial variability of riverbed temperature gradients in Snake River fall Chinook salmon spawning areas

    SciTech Connect

    Hanrahan, Timothy P.

    2007-02-01

    In the Snake River basin of the Pacific northwestern United States, hydroelectric dam operations are often based on the predicted emergence timing of salmon fry from the riverbed. The spatial variability and complexity of surface water and riverbed temperature gradients results in emergence timing predictions that are likely to have large errors. The objectives of this study were to quantify the thermal heterogeneity between the river and riverbed in fall Chinook salmon spawning areas and to determine the effects of thermal heterogeneity on fall Chinook salmon emergence timing. This study quantified river and riverbed temperatures at 15 fall Chinook salmon spawning sites distributed in two reaches throughout 160 km of the Snake River in Hells Canyon, Idaho, USA, during three different water years. Temperatures were measured during the fall Chinook salmon incubation period with self-contained data loggers placed in the river and at three different depths below the riverbed surface. At all sites temperature increased with depth into the riverbed, including significant differences (p<0.05) in mean water temperature of up to 3.8°C between the river and the riverbed among all the sites. During each of the three water years studied, river and riverbed temperatures varied significantly among all the study sites, among the study sites within each reach, and between sites located in the two reaches. Considerable variability in riverbed temperatures among the sites resulted in fall Chinook salmon emergence timing estimates that varied by as much as 55 days, depending on the source of temperature data used for the estimate. Monitoring of riverbed temperature gradients at a range of spatial scales throughout the Snake River would provide better information for managing hydroelectric dam operations, and would aid in the design and interpretation of future empirical research into the ecological significance of physical riverine processes.

  7. Keywords. Biological variables; enthalpy-entropy compensation; temperature-dependence data J. Biosci. | Vol. 27 | No. 2 | March 2002 | 121126 | Indian Academy of Sciences

    E-print Network

    that live at signi- ficantly different temperatures, and for each enzyme the temperature dependence that accompany variations in the temperature at which each enzyme is normally active are "compensated for121 Keywords. Biological variables; enthalpy-entropy compensation; temperature-dependence data J

  8. Variable Temperatures Improves Survival of the Alfalfa Leafcutting Bee During Cold Storage

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Megachile rotundata are commonly held at low-temperatures for overwintering the prepupae or interrupting the spring incubation to synchronize the adult emergence with the peak alfalfa bloom. However, low-temperature exposure can be stressful depending on the temperature, duration of exposure, and th...

  9. Evaluation of the stimulating effects of temperature and humidity in Poland in a meridional cross-section in the years 1976-2005

    NASA Astrophysics Data System (ADS)

    Ara?ny, Andrzej; Smuka?a, Kamila

    2011-01-01

    In this study an evaluation is made of the stimulating influence of thermal and humidity conditions at the following four stations: Hel, Toru?-Wrzosy, ?ód?-Lublinek, and Katowice. The diversity of thermal conditions and humidity was analyzed with relation to the mean daily temperature of air and its humidity, day-to-day variability of temperature, daily temperature ranges and thermally characteristic days (e.g. heat, very frosty and sultry). Days perceived as cold (with the mean daily temperature of air ? 10°C) were observed most often in Hel (57% of the days) and slightly less often in the other stations (about 55%). Significant day-to-day changes of the mean daily temperature provide a strong thermal stimulus. Such day-to-day changes of temperature, perceived by the human body, occurred from 18% in Hel to 27% in Katowice, whereas substantial thermal stimuli occurred from 2.5% at the seaside station to over 7% in Toru?. Severe stimuli with irritating effects were observed occasionally in Hel (0.4%) and for about 2% of the time at the other stations. The daily temperature range demonstrates a close relationship with the distance from the Baltic Sea. The frequency of neutral stimuli ranged from 13% in Katowice, to 16% in ?ód? and Toru?, and to 34% in Hel. Barely perceptible daily thermal contrasts were observed for 43% of the days at the seaside station, whereas the frequency at the other stations was about 33%. For the human body, the amplitudes of 12°C or more are very uncomfortable and these were observed from 6% (Hel) to 27% of days (Katowice). As regards the values of relative humidity of the air the seaside station clearly stands out with half of the days characterised by very high atmospheric humidity. The driest air was found to occur in Katowice (high humidity perceived on only 29% of the days). On average, there are few heat days per year in Poland and they are the least frequent on the coast. The mean number of very frosty days per year ranged from 0.3 in Hel to 1.5 in ?ód?. The most of sultry days were observed in the seaside belt, where the atmospheric humidity is increased.

  10. Development of alternate silicone potting compounds. Volume 11. Influences of temperature, material variables, and composition variables on the properties of substitute potting compounds

    SciTech Connect

    Cady, W.E.

    1983-01-01

    We evaluated the effect that Sylgard 184 and 186 and Dielectric Gel Q3-6527 have on the mechanical properties of cured Sylgard starting materials, cured APC2.5, and APC10 substitute potting compounds. We looked specifically at the influences of five variables of 184, 186, and Q3-6527 on the 25/sup 0/C mechanical properties, namely temperature, platinum content of the accelerator, amount of accelerator used, reactivity, and viscosity. Within limited ranges, the platinum content of the accelerator and the amount of accelerator used had no effect on the mechanical properties of cured silicones. The reactivity and viscosity of the major components (184, 186, and Q3) had only two slight effects on the mechanical properties and thermal stability of the cured APC compounds. We checked lot variations on Sylgards 184 and 186 and ingredient variations on APC2.5, 10, and 300 compounds. Sylgards 184 and 186 vary from lot to lot, but the variability is moderate and of the same magnitude as testing variability. For the cured APC compounds, mechanical properties vary considerably depending upon the type of ingredients used in the formulation, whereas thermal properties are less sensitive. Compressive strength depends greatly upon the types of ingredients in the formulation.

  11. Variability of ice sheet thickness and water temperature in Arctic major rivers

    NASA Astrophysics Data System (ADS)

    PARK, H.; Yoshikawa, Y.; Oshima, K.

    2014-12-01

    Increasing river discharge to the Arctic Ocean is a very significant change in the Arctic system. Increase in surface temperature in the Arctic over the past decades was exceptionally higher in the history of arctic observations. The increased temperature resulted in changes in ice freezing and melting and water temperature in Arctic rivers. However, there are significant knowledge gaps in our understanding of the river-ice dynamics and river water temperature. Therefore, we assessed changes in ice sheet thickness, the timing of ice freezing and melting, and water temperature in Arctic major rivers during the period 1979-2009, based on observations and a hydrological model. The model can estimate ice thickness and water temperature using air temperature, snow depth, and river discharge. The calculated ice thickness and water temperature were compared with observations, showing generally significant correlations. The observed and calculated maximum ice thickness indicated decreasing trends at the outlet and inner points of rivers. The timing of ice breakup was also advanced. These changes were mostly significant during the recent three decades when the increase in air temperature was significant. The model also estimated increasing water temperatures, which is consistent with the observations. The warming of water temperature suggests influences on heat budget in the Arctic Ocean. This study validated the applicability for river-ice calculation of the hydrological model, and the model simulation provided useful information relating to the changing river-ice environments in the Arctic rivers.

  12. Reduction of variable range hopping conduction in low-temperature molecular-beam epitaxy GaAs

    NASA Astrophysics Data System (ADS)

    Albuquerque, H. A.; de Oliveira, A. G.; Ribeiro, G. M.; da Silva, R. L.; Rodrigues, W. N.; Rubinger, R. M.

    2004-04-01

    Studying the transport properties via Hall and resistivity measurements of low-temperature molecular-beam epitaxy (LT-MBE) GaAs samples, the optimal conditions for fabricating high-resistivity material are found. We present results on three LT-MBE GaAs samples grown at 215, 265, and 315 °C. The measurements were carried out at temperatures ranging from 130 to 300 K, and the hopping conduction mechanism in this range is identified as variable range hopping. The sample grown at 315 °C presents the highest hopping parameter; this appears to be due to a reduction in the density of hopping centers. The mechanisms responsible for this are discussed.

  13. The bi-variate frequency distribution of two concurrent climatic variables: a study of temperature and dew point 

    E-print Network

    Zeitler, Jon William

    1991-01-01

    variables to a bi-variate theoretical distribution. A likely reason for this is the lack of historical. concurrent observations, coupled with a previous lack of computer capability for handling data. The recent implementation of automated observation... calculations can be made for selected stations in Texas. The specific objectives of this study will be to: (1) Establish and identify statistical properties of the temperature and dew point data. (2) Attempt to develop methods for computing joint...

  14. Immediate Effects of Reiki on Heart Rate Variability, Cortisol Levels, and Body Temperature in Health Care Professionals With Burnout

    Microsoft Academic Search

    Lourdes Díaz-Rodríguez; Manuel Arroyo-Morales; Cesar Fernández-de-las-Peñas; Francisca García-Lafuente; Carmen García-Royo; Inmaculada Tomás-Rojas

    2011-01-01

    Burnout is a work-related mental health impairment comprising three dimensions: emotional exhaustion, depersonalization, and reduced personal accomplishment. Reiki aims to help replenish and rebalance the body’s energetic system, thus stimulating the healing process. The objective of this placebo-controlled, repeated measures, crossover, single-blind, randomized trial was to analyze the immediate effects of Reiki on heart rate variability (HRV), body temperature, and

  15. Temperature-dependent activation energy and variable range hopping in semi-insulating GaAs

    NASA Astrophysics Data System (ADS)

    Rubinger, R. M.; Ribeiro, G. M.; de Oliveira, A. G.; Albuquerque, H. A.; da Silva, R. L.; Rubinger, C. P. L.; Rodrigues, W. N.; Moreira, M. V. B.

    2006-12-01

    We measured resistivity in the range of 30-390 K on four semi-insulating low-temperature grown molecular-beam epitaxy GaAs samples. The growth temperature range was from 215 °C to 315 °C. Arrhenius fittings with T-1 and hopping fitting with T-1/4 do not permit us the definition of the temperature ranges controlled by band and hopping conduction, respectively. This leads to major errors in the calculation of both activation energies and hopping parameters. We have used the differential activation energy in order to clearly identify the temperature range for the different transport mechanisms. Hopping dominates at low temperatures and band conduction at high temperatures. In-between, a mixed conduction regime is observed. We introduce a criterion to clearly define the temperature range of hopping, band and mixed conduction. The lower temperature at which mixed conduction is identified decreases for samples with increasing growth temperature. Only the sample grown at 215 °C presents both forms of hopping conduction before entering the mixed conduction regime. Hopping parameters were obtained from the fittings of the differential activation energy and the values are in good agreement with the usual method of calculating them if the correct temperature range is used.

  16. Performance of a Herriott Cell, Designed for Variable Temperatures between 296 and 20 K

    NASA Technical Reports Server (NTRS)

    Mondelain, Didier; Camy-Peyret, Claude; Mantz, Arlan W.; Tang, Emma; Valentin, Alain

    2007-01-01

    We designed, fabricated and tested a multipath Herriott cell (or off-axis spherical mirror interferometer) to achieve low temperature absorption measurements. The cell is fabricated entirely from copper and the 15 cm radius of curvature copper mirrors have gold coated reflective surfaces. The cell was tested at temperatures between 296 and 30 K with a folded absorption path length of 5.37 m utilizing a lead salt tunable diode laser. Short term temperature stability (1 h) of the Herriott cell is better than 0.005 K under normal operating conditions with a temperature uniformity better than 0.01 K (not measurable). The cell was tested by performing collisional cooling experiments on 13C16O2 in helium at temperatures between 70 and 20 K and by performing more traditional pressure broadening and shift measurements on molecular infrared absorption lines at temperatures between 300 and about 80 K on 13C16O2 methane.

  17. THE INFLUENCE OF VARIABLE TEMPERATURE AND HUMIDITY ON THE PREDATION EFFICIENCY OF P. PERSIMILIS, N. CALIFORNICUS AND N. FALLACIS.

    PubMed

    Audenaert, J; Vangansbeke, D; Verhoeven, R; De Clercq, P; Tirry, L; Gobin, B

    2014-01-01

    Predatory mites like Phytoseiulus persimilis Athias-Henriot, Neoseiulus californicus McGregor and N. fallacis (Garman) (Acari: Phytoseiidae) are essential in sustainable control strategies of the two-spotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae) in warm greenhouse cultures to complement imited available pesticides and to tackle emerging resistance. However, in response to high energy prices, greenhouse plant breeders have recently changed their greenhouse steering strategies, allowing more variation in temperature and humidity. The impact of these variations on biological control agents is poorly understood. Therefore, we constructed functional response models to demonstrate the impact of realistic climate variations on predation efficiency. First, two temperature regimes were compared at constant humidity (70%) and photoperiod (16L:8D): DIF0 (constant temperature) and DIF15 (variable temperature with day-night difference of 15°C). At mean temperatures of 25°C, DIF15 had a negative influence on the predation efficiency of P. persimilis and N. californicus, as compared to DIF0. At low mean temperatures of 15°C, however, DIF15 showed a higher predation efficiency for P. persimilis and N. californicus. For N. fallacis no difference was observed at both 15°C and 25°C. Secondly, two humidity regimes were compared, at a mean temperature of 25°C (DIFO) and constant photoperiod (16L:8D): RHCTE (constant 70% humidity) and RHALT (alternating 40% L:70%D humidity). For P. persimilis and N. fallacis RHCTE resulted in a higher predation efficiency than RHALT, for N. californicus this effect was opposite. This shows that N. californicus is more adapted to dry climates as compared to the other predatory mites. We conclude that variable greenhouse climates clearly affect predation efficiency of P. persimilis, N. californicus and N. fallacis. To obtain optimal control efficiency, the choice of predatory mites (including dose and application frequency) should be adapted to the actual greenhouse climate. PMID:26084089

  18. The Schaake shuffle: A method for reconstructing space-time variability in forecasted precipitation and temperature fields

    USGS Publications Warehouse

    Clark, M.; Gangopadhyay, S.; Hay, L.; Rajagopalan, B.; Wilby, R.

    2004-01-01

    A number of statistical methods that are used to provide local-scale ensemble forecasts of precipitation and temperature do not contain realistic spatial covariability between neighboring stations or realistic temporal persistence for subsequent forecast lead times. To demonstrate this point, output from a global-scale numerical weather prediction model is used in a stepwise multiple linear regression approach to downscale precipitation and temperature to individual stations located in and around four study basins in the United States. Output from the forecast model is downscaled for lead times up to 14 days. Residuals in the regression equation are modeled stochastically to provide 100 ensemble forecasts. The precipitation and temperature ensembles from this approach have a poor representation of the spatial variability and temporal persistence. The spatial correlations for downscaled output are considerably lower than observed spatial correlations at short forecast lead times (e.g., less than 5 days) when there is high accuracy in the forecasts. At longer forecast lead times, the downscaled spatial correlations are close to zero. Similarly, the observed temporal persistence is only partly present at short forecast lead times. A method is presented for reordering the ensemble output in order to recover the space-time variability in precipitation and temperature fields. In this approach, the ensemble members for a given forecast day are ranked and matched with the rank of precipitation and temperature data from days randomly selected from similar dates in the historical record. The ensembles are then reordered to correspond to the original order of the selection of historical data. Using this approach, the observed intersite correlations, intervariable correlations, and the observed temporal persistence are almost entirely recovered. This reordering methodology also has applications for recovering the space-time variability in modeled streamflow. ?? 2004 American Meteorological Society.

  19. Investigating variability in catch rates of halibut ( Hippoglossus stenolepis) in the Pribilof Islands: Is temperature important?

    NASA Astrophysics Data System (ADS)

    Loher, Timothy

    2008-08-01

    From 2002 to 2004, a study was conducted to test the hypothesis that commercial catch per unit effort (CPUE) of Pacific halibut ( Hippoglossus stenolepis) in the Pribilof Islands local fishery varies on intra-annual (weeks-months) and inter-annual (among fishing seasons) time scales due to (a) variation in seasonal migration timing, (b) temperature-dependent habitat preference, or (c) average local abundance governed by late spring hydrographic conditions. Changes in CPUE over the progression of three fishing seasons were examined for evidence of seasonal migration signals. Relationships between catch and water temperature were examined by deploying temperature recorders from local commercial vessels and correlating the observations with vessel-standardized CPUE intra- and inter-annually. Temperature data were obtained from 735-longline sets; simultaneous depth data were collected from a subset of 412 of those deployments. Annual temperature data clearly demonstrated seasonal warming trends, and temperature was negatively correlated with depth. Warmest conditions were observed in 2003: maximum temperatures of ˜6 °C were observed in early June and increased to ˜10 °C in early September. Conditions in 2002 and 2004 were similar to one another and on average about 1 °C cooler than in 2003, warming from ˜5 °C in June to ˜9.5 °C in September. No intra-annual trend in CPUE was apparent. A relationship was not detected between temperature and vessel-standardized CPUE within years, whether CPUE was compared to absolute temperature or the difference between observed temperature and daily-predicted maximum. These results suggest that halibut do not respond strongly to temperatures within the observed range, nor was there evidence that the fishery was influenced by seasonal movement patterns. These conclusions are supported by concurrent archival tagging that suggests the Pribilof fishery may be too short to capture seasonal migration periods; summer local abundance is likely established prior to commencement of the fishery. Temperatures observed by the fleet were also within the known thermal tolerances of Pacific halibut. Inter-annually, cumulative fleet-wide CPUE and total catch were associated with coolest annual mean temperature. A relationship might exist between annual CPUE and mean temperature, but the available time series is too short to draw conclusions in this regard. While there was no trend in CPUE from June through August or across temperatures ranging from 5 to 10 °C, the results may be valuable in refining hypotheses and focusing future effort. Additional research should seek to examine catch trends earlier and later in the year, as well as at higher and lower temperatures, perhaps at the edges of the species's geographic range or during years characterized by anomalous hydrographic conditions.

  20. Temperature-phase converter based on a LC cell as a variable capacitance.

    PubMed

    Torres, Juan Carlos; García-Cámara, Braulio; Pérez, Isabel; Urruchi, Virginia; Sánchez-Pena, José Manuel

    2015-01-01

    The main characteristic of liquid crystals is that their properties, both electrical and optical, can be modified through a convenient applied signal, for instance a certain voltage. This tunable behavior of liquid crystals is directly related to the orientation of their nanometric components with respect to a director direction. However, the initial alignment is a fabrication-dependent parameter and may be either planar or homeotropic. In addition, the strong dependence of the properties of liquid crystals with the temperature is well known and widely used for several temperature sensors. This dependence is produced by the influence of the temperature on the ordering of the molecules. In this work, we have studied the temperature dependence of the electric properties of a liquid crystal cell, in particular the dielectric permittivity, with the temperature as a function of the initial alignment set during the fabrication process. Starting from experimental measurements, an equivalent circuit model including the temperature dependence has been proposed. We have observed that a good linearity in a wide temperature range is provided at a suitable exciting frequency. Finally, a proper conditioner circuit is proposed as a powerful tool for linear and high sensibility temperature measurement. PMID:25756866

  1. Temperature is the dominant environmental variable affecting the distribution and abundance of organisms.

    E-print Network

    Ahmad, Sajjad

    of the cuticle, which forms the primary barrier to cuticular transpiration (Hadley, 1994a). Surface lipids-length hydrocarbons provide a better barrier to transpiration, as a result of their higher melting temperatures Drosophila mojavensis experiences environmental conditions of high temperature and low humidity

  2. European Seasonal and Annual Temperature Variability, Trends, and Extremes Since 1500

    Microsoft Academic Search

    Jürg Luterbacher; Daniel Dietrich; Elena Xoplaki; Martin Grosjean; Heinz Wanner

    2004-01-01

    Multiproxy reconstructions of monthly and seasonal surface temperature fields for Europe back to 1500 show that the late 20th- and early 21st-century European climate is very likely (>95% confidence level) warmer than that of any time during the past 500 years. This agrees with findings for the entire Northern Hemisphere. European winter average temperatures during the period 1500 to 1900

  3. A new variable temperature solution-solid interface scanning tunneling microscope.

    PubMed

    Jahanbekam, Abdolreza; Mazur, Ursula; Hipps, K W

    2014-10-01

    We present a new solution-solid (SS) interface scanning tunneling microscope design that enables imaging at high temperatures with low thermal drift and with volatile solvents. In this new design, distinct from the conventional designs, the entire microscope is surrounded in a controlled-temperature and controlled-atmosphere chamber. This allows users to take measurements at high temperatures while minimizing thermal drift. By incorporating an open solution reservoir in the chamber, solvent evaporation from the sample is minimized; allowing users to use volatile solvents for temperature dependent studies at high temperatures. The new design enables the user to image at the SS interface with some volatile solvents for long periods of time (>24 h). An increase in the nonlinearity of the piezoelectric scanner in the lateral direction as a function of temperature is addressed. A temperature dependent study of cobalt(II) octaethylporphyrin (CoOEP) at the toluene/Au(111) interface has been performed with this instrument. It is demonstrated that the lattice parameters remain constant within experimental error from 24?°C to 75?°C. Similar quality images were obtained over the entire temperature range. We report the unit cell of CoOEP at the toluene/Au(111) interface (based on two molecules per unit cell) to be A = (1.36 ± 0.04) nm, B = (2.51 ± 0.04) nm, and ? = 97° ± 2°. PMID:25362397

  4. Long-term variability of the temperature time series recorded in Lisbon

    Microsoft Academic Search

    João Santos; Solange Leite

    2009-01-01

    As a case study for application in climate change studies, daily air temperature records in Lisbon are analysed by applying advanced statistical methodologies that take into account the dynamic nature of climate. A trend analysis based on two non-parametric tests (Spearman and Mann–Kendall) revealed the presence of statistically significant upward trends in the maximum temperatures, mainly during March. The minimum

  5. Thermal performance of cross flow cooling towers in variable wet bulb temperature

    Microsoft Academic Search

    Ebrahim Hajidavalloo; Reza Shakeri; Mozaffar A. Mehrabian

    2010-01-01

    Cooling towers are widely used in most industrial units to reject waste heat to the atmosphere. Wet towers are usually designed to operate in hot and dry weather conditions with narrow range of wet bulb temperature, but many cooling towers are required to operate in weather condition with large variation of wet bulb temperature which strongly affects the thermal performance

  6. Temperature-Phase Converter Based on a LC Cell as a Variable Capacitance

    PubMed Central

    Torres, Juan Carlos; García-Cámara, Braulio; Pérez, Isabel; Urruchi, Virginia; Sánchez-Pena, José Manuel

    2015-01-01

    The main characteristic of liquid crystals is that their properties, both electrical and optical, can be modified through a convenient applied signal, for instance a certain voltage. This tunable behavior of liquid crystals is directly related to the orientation of their nanometric components with respect to a director direction. However, the initial alignment is a fabrication-dependent parameter and may be either planar or homeotropic. In addition, the strong dependence of the properties of liquid crystals with the temperature is well known and widely used for several temperature sensors. This dependence is produced by the influence of the temperature on the ordering of the molecules. In this work, we have studied the temperature dependence of the electric properties of a liquid crystal cell, in particular the dielectric permittivity, with the temperature as a function of the initial alignment set during the fabrication process. Starting from experimental measurements, an equivalent circuit model including the temperature dependence has been proposed. We have observed that a good linearity in a wide temperature range is provided at a suitable exciting frequency. Finally, a proper conditioner circuit is proposed as a powerful tool for linear and high sensibility temperature measurement. PMID:25756866

  7. Optimum variables selection of thermoelectric generator-driven thermoelectric refrigerator at different source temperature

    Microsoft Academic Search

    Lingen Chen; Fankai Meng; Yanlin Ge; Fengrui Sun

    2012-01-01

    Based on the finite time thermodynamic model of thermoelectric generator-driven thermoelectric refrigerator with losses of external heat transfer, Joulean heat inside the thermoelectric device and the heat leakage through the thermoelectric couple leg, this paper analysed the effects of generator heat source temperature and refrigerator cooling temperature on the performance of the combined system using the combination of finite time

  8. Oxygen isotope variability in snow from western Dronning Maud Land, Antarctica and its relation to temperature

    Microsoft Academic Search

    M. M. H ELSEN; R. S. W. VA N D E WA; M. R. V AN D EN; D. VA N A S

    This paper presents ?18O records from snow pits from four locations in Dronning Maud Land, Antarctica that contain at least four annual cycles. The aim of the study was to analyse in detail these records as well as the prevailing temperatures during accumulation in order to infer to what extent isotopic composition in this area can be interpreted as temperature

  9. Oxygen isotope variability in snow from western Dronning Maud Land, Antarctica and its relation to temperature

    Microsoft Academic Search

    M. M. Helsen; M. R. van den Broeke; D. van As; H. A. J. Meijer; C. H. Reijmer

    2005-01-01

    This paper presents delta18O records from snow pits from four locations in Dronning Maud Land, Antarctica that contain at least four annual cycles. The aim of the study was to analyse in detail these records as well as the prevailing temperatures during accumulation in order to infer to what extent isotopic composition in this area can be interpreted as temperature

  10. Simulations of Atmospheric Variability Induced by Sea Surface Temperatures and Implications for Global Warming

    Microsoft Academic Search

    Arun Kumar; Ants Leetmaa; Ming Ji

    1994-01-01

    An atmospheric general circulation model was forced with observed interannual changes in the global sea surface temperatures (SSTs) for the period 1982 to 1993. The simulated seasonal surface air temperature patterns over land areas closely resemble the observed. Over most of the globe, the patterns also resemble those associated with El Nino events and are also reproduced in simulations with

  11. Identifying spatial variability of groundwater discharge in a wetland stream using a distributed temperature sensor

    USGS Publications Warehouse

    Lowry, C.S.; Walker, J.F.; Hunt, R.J.; Anderson, M.P.

    2007-01-01

    Discrete zones of groundwater discharge in a stream within a peat-dominated wetland were identified on the basis of variations in streambed temperature using a distributed temperature sensor (DTS). The DTS gives measurements of the spatial (??1 m) and temporal (15 min) variation of streambed temperature over a much larger reach of stream (>800 m) than previous methods. Isolated temperature anomalies observed along the stream correspond to focused groundwater discharge zones likely caused by soil pipes within the peat. The DTS also recorded variations in the number of temperature anomalies, where higher numbers correlated well with a gaining reach identified by stream gauging. Focused zones of groundwater discharge showed essentially no change in position over successive measurement periods. Results suggest DTS measurements will complement other techniques (e.g., seepage meters and stream gauging) and help further improve our understanding of groundwater-surface water dynamics in wetland streams. Copyright 2007 by the American Geophysical Union.

  12. An optics-based variable-temperature assay system for characterizing thermodynamics of biomolecular reactions on solid support

    NASA Astrophysics Data System (ADS)

    Fei, Yiyan; Landry, James P.; Li, Yanhong; Yu, Hai; Lau, Kam; Huang, Shengshu; Chokhawala, Harshal A.; Chen, Xi; Zhu, X. D.

    2013-11-01

    A biological state is equilibrium of multiple concurrent biomolecular reactions. The relative importance of these reactions depends on physiological temperature typically between 10 °C and 50 °C. Experimentally the temperature dependence of binding reaction constants reveals thermodynamics and thus details of these biomolecular processes. We developed a variable-temperature opto-fluidic system for real-time measurement of multiple (400-10 000) biomolecular binding reactions on solid supports from 10 °C to 60 °C within ±0.1 °C. We illustrate the performance of this system with investigation of binding reactions of plant lectins (carbohydrate-binding proteins) with 24 synthetic glycans (i.e., carbohydrates). We found that the lectin-glycan reactions in general can be enthalpy-driven, entropy-driven, or both, and water molecules play critical roles in the thermodynamics of these reactions.

  13. An optics-based variable-temperature assay system for characterizing thermodynamics of biomolecular reactions on solid support

    PubMed Central

    Fei, Yiyan; Landry, James P.; Li, Yanhong; Yu, Hai; Lau, Kam; Huang, Shengshu; Chokhawala, Harshal A.; Chen, Xi; Zhu, X. D.

    2013-01-01

    A biological state is equilibrium of multiple concurrent biomolecular reactions. The relative importance of these reactions depends on physiological temperature typically between 10?°C and 50?°C. Experimentally the temperature dependence of binding reaction constants reveals thermodynamics and thus details of these biomolecular processes. We developed a variable-temperature opto-fluidic system for real-time measurement of multiple (400–10?000) biomolecular binding reactions on solid supports from 10?°C to 60?°C within ±0.1?°C. We illustrate the performance of this system with investigation of binding reactions of plant lectins (carbohydrate-binding proteins) with 24 synthetic glycans (i.e., carbohydrates). We found that the lectin-glycan reactions in general can be enthalpy-driven, entropy-driven, or both, and water molecules play critical roles in the thermodynamics of these reactions. PMID:24289409

  14. Distinguishing Loss of Structure from Subunit Dissociation for Protein Complexes with Variable Temperature Ion Mobility Mass Spectrometry.

    PubMed

    Pacholarz, Kamila J; Barran, Perdita E

    2015-06-16

    The thermal stability and strength of interactions in proteins are commonly measured using isothermal calorimetry and differential scanning calorimetry providing a measurement that averages over structural transitions that occur as the proteins melt and dissociate. Here, we apply variable temperature ion mobility mass spectrometry (VT-IM-MS) to study the effect of temperature on the stability and structure of four multimeric protein complexes. VT-IM-MS is used here to investigate the change in the conformation of model proteins, namely, transthyretin (TTR), avidin, concanavalin A (conA), and human serum amyloid P component (SAP) at elevated temperatures prior, during, and after dissociation up to 550 K. As the temperature of the buffer gas is increased from 300 to 350 K, a small decrease in the collision cross sections ((DT)CCSHe) of protein complexes from the values at room temperature is observed, and is associated with complex compaction occurring close to the reported solution Tm. At significantly higher temperatures, each protein complex undergoes an increase in (DT)CCSHe and in the width of arrival time distributions (ATD), which is attributed to extensive protein unfolding, prior to ejection of a highly charged monomer species. This approach allows us to decouple the distinct gas phase melting temperature (Tm) from the temperature at which we see subunit dissociation. The thermally induced dissociation (TID) mechanism is observed to initially proceed via the so-called "typical" (CID) dissociation route. Interestingly, data collected at higher analysis temperature suggests that the TID process might be adapting more "atypical" dissociation route. PMID:25993423

  15. Analysis of trait mean and variability versus temperature in trematode cercariae: is there scope for adaptation to global warming?

    PubMed

    Studer, A; Poulin, R

    2014-05-01

    The potential of species for evolutionary adaptation in the context of global climate change has recently come under scrutiny. Estimates of phenotypic variation in biological traits may prove valuable for identifying species, or groups of species, with greater or lower potential for evolutionary adaptation, as this variation, when heritable, represents the basis for natural selection. Assuming that measures of trait variability reflect the evolutionary potential of these traits, we conducted an analysis across trematode species to determine the potential of these parasites as a group to adapt to increasing temperatures. Firstly, we assessed how the mean number of infective stages (cercariae) emerging from infected snail hosts as well as the survival and infectivity of cercariae are related to temperature. Secondly and importantly in the context of evolutionary potential, we assessed how coefficients of variation for these traits are related to temperature, in both cases controlling for other factors such as habitat, acclimatisation, latitude and type of target host. With increasing temperature, an optimum curve was found for mean output and mean infectivity, and a linear decrease for survival of cercariae. For coefficients of variation, temperature was only an important predictor in the case of cercarial output, where results indicated that there is, however, no evidence for limited trait variation at the higher temperature range. No directional trend was found for either variation of survival or infectivity. These results, characterising general patterns among trematodes, suggest that all three traits considered may have potential to change through adaptive evolution. PMID:24675554

  16. Interannual variability of temperature at a depth of 125 meters in the North Atlantic Ocean

    SciTech Connect

    Levitus, S.; Boyer, T.P. [National Oceanographic Data Center, Washington, DC (United States); Antonov, J.I. [State Hydrological Institute, St. Petersburg (Russian Federation)

    1994-10-07

    Analyses of historical ocean temperature data at a depth of 125 meters in the North Atlantic Ocean indicate that from 1950-1990 the subtropical and subartic gyres exhibited linear trends that were opposite in phase. In addition, multivariate analyses of yearly mean temperature anomaly fields between 20{degrees}N and 70{degrees}N in the North Atlantic show a characteristic space-time temperature oscillation from 1947 to 1990. A quasidecadal oscillation, first-identified at Ocean Weather Station C, is part of a basin-wide feature. Gyre and basin-scale variations such as these provide the observational basis for climate diagnostic and modeling studies.

  17. In Situ Acoustic Temperature Measurement During Variable-Frequency Microwave Curing

    Microsoft Academic Search

    Cleon E. Davis; Anthony J. Dickherber; William D. Hunt; Gary S. May

    2008-01-01

    Variable-frequency microwave (VFM) curing can perform the same processing steps as conventional thermal processing in minutes, without compromising intrinsic material properties. With increasing demand for novel dielectrics, there is a corresponding demand for new processing techniques that lead to comparable or better properties than conventional methods. VFM processing can be a viable alternative to conventional thermal techniques. However, current limitations

  18. Estuarine intertidal sediment temperature variability in Zoster marina and Z. japonica habitats in Yaquina Bay, Oregon

    EPA Science Inventory

    Physical characterization of intertidal estuarine plant habitats over time may reveal distribution-limiting thresholds. Temperature data from loggers embedded in sediment in transects crossing Zostera marina and Z. japonica habitats in lower Yaquina Bay, Oregon display signific...

  19. High-temperature electrical resistivity of rare-earth metals with variable valence

    SciTech Connect

    Povzner, A.A.; Abel'skii, S.S.

    1986-11-01

    The electrical resistivity of compounds of rare-earth metals at high temperatures is calculated on the basis of allowance for the background mechanism of scattering and the hybridization of local electron states with the states of conduction electrons. An analytic expression is obtained for resistivity in a strong hybridization approximation. It follows from the expression that electrical resistivity may have a negative temperature coefficient within a broad range of high temperatures. The use of a three-band (s, d, f) model makes it possible to explain experimental data on the resistivity of certain rare-earth metals, particularly the connection between the sign of the temperature coefficient of electrical resistivity and the curvature of the relation (T).

  20. Infrared-temperature variability in a large agricultural field. [Dunnigan, California

    NASA Technical Reports Server (NTRS)

    Millard, J. P.; Goettelman, R. C.; Leroy, M. L. (principal investigators)

    1980-01-01

    The combined effect of water carved gullies, varying soil color, moisture state of the soil and crop, nonuniform phenology, and bare spots was measured for commercially grown barley planted on varying terrain. For all but the most rugged terrain, over 80% of the area within 4, 16, 65, and 259 ha cells was at temperatures within 3 C of the mean cell temperature. The result of using relatively small, 4 ha instantaneous field of views for remote sensing applications is that either the worst or the best of conditions is often observed. There appears to be no great advantage in utilizing a small instantaneous field of view instead of a large one for remote sensing of crop canopy temperatures. The two alternatives for design purposes are then either a very high spatial resolution, of the order of a meter or so, where the field is very accurately temperature mapped, or a low resolution, where the actual size seems to make little difference.

  1. INFLUENCE OF SUMMER TEMPERATURE SPATIAL VARIABILITY ON DISTRIBUTION AND CONDITION OF JUVENILE COHO SALMON

    EPA Science Inventory

    abstract Temperature during the summer months can influence the distribution, abundance and physiology of stream salmonids such as coho salmon (Oncorhynchus kisutch). Effects can be direct, via physiological responses, as well as indirect, via limited food resources, alter...

  2. Variable-range hopping conduction in doped germanium at very low temperatures and high magnetic fields

    Microsoft Academic Search

    W. Schoepe; Universitfit Regensburg

    1988-01-01

    The conductivity of doped Ge below the metal-insulator transition is measured at temperatures between 4 K and 40 mK and in magnetic fields up to 7 Tesla. In zero field the resistivity exponent diverges asT-1\\/2. In weak fields the magnetoresistance increases asB2 and becomes exponentially large in strong fields and at low temperatures. The results can be described quantitatively in

  3. The effect of two-temperature post-shock accretion flow on the linear polarization pulse in magnetic cataclysmic variables

    E-print Network

    Gordon E. Sarty; Curtis J. Saxton; Kinwah Wu

    2008-08-05

    The temperatures of electrons and ions in the post-shock accretion region of a magnetic cataclysmic variable (mCV) will be equal at sufficiently high mass flow rates or for sufficiently weak magnetic fields. At lower mass flow rates or in stronger magnetic fields, efficient cyclotron cooling will cool the electrons faster than the electrons can cool the ions and a two-temperature flow will result. Here we investigate the differences in polarized radiation expected from mCV post-shock accretion columns modeled with one- and two-temperature hydrodynamics. In an mCV model with one accretion region, a magnetic field >~30 MG and a specific mass flow rate of ~0.5 g/cm/cm/s, along with a relatively generic geometric orientation of the system, we find that in the ultraviolet either a single linear polarization pulse per binary orbit or two pulses per binary orbit can be expected, depending on the accretion column hydrodynamic structure (one- or two-temperature) modeled. Under conditions where the physical flow is two-temperature, one pulse per orbit is predicted from a single accretion region where a one-temperature model predicts two pulses. The intensity light curves show similar pulse behavior but there is very little difference between the circular polarization predictions of one- and two-temperature models. Such discrepancies indicate that it is important to model some aspect of two-temperature flow in indirect imaging procedures, like Stokes imaging, especially at the edges of extended accretion regions, were the specific mass flow is low, and especially for ultraviolet data.

  4. Sample mounting and transfer for coupling an ultrahigh vacuum variable temperature beetle scanning tunneling microscope with conventional surface probes

    SciTech Connect

    Nafisi, Kourosh; Ranau, Werner; Hemminger, John C.

    2001-01-01

    We present a new ultrahigh vacuum (UHV) chamber for surface analysis and microscopy at controlled, variable temperatures. The new instrument allows surface analysis with Auger electron spectroscopy, low energy electron diffraction, quadrupole mass spectrometer, argon ion sputtering gun, and a variable temperature scanning tunneling microscope (VT-STM). In this system, we introduce a novel procedure for transferring a sample off a conventional UHV manipulator and onto a scanning tunneling microscope in the conventional ''beetle'' geometry, without disconnecting the heating or thermocouple wires. The microscope, a modified version of the Besocke beetle microscope, is mounted on a 2.75 in. outer diameter UHV flange and is directly attached to the base of the chamber. The sample is attached to a tripod sample holder that is held by the main manipulator. Under UHV conditions the tripod sample holder can be removed from the main manipulator and placed onto the STM. The VT-STM has the capability of acquiring images between the temperature range of 180--500 K. The performance of the chamber is demonstrated here by producing an ordered array of island vacancy defects on a Pt(111) surface and obtaining STM images of these defects.

  5. Influence of cosmic-ray variability on the monsoon rainfall and temperature

    E-print Network

    Badruddin,

    2014-01-01

    We study the role of galactic cosmic ray (GCR) variability in influencing the rainfall variability in Indian Summer Monsoon Rainfall (ISMR) season. We find that on an average during 'drought' (low ISMR) periods in India, GCR flux is decreasing, and during 'flood' (high ISMR) periods, GCR flux is increasing. The results of our analysis suggest for a possibility that the decreasing GCR flux during the summer monsoon season in India may suppress the rainfall. On the other hand, increasing GCR flux may enhance the rainfall. We suspect that in addition to real environmental conditions, significant levitation/dispersion of low clouds and hence reduced possibility of collision/coalescence to form raindrops suppresses the rainfall during decreasing GCR flux in monsoon season. On the other hand, enhanced collision/coalescence efficiency during increasing GCR flux due to electrical effects may contribute to enhancing the rainfall. Based on the observations, we put forward the idea that, under suitable environmental con...

  6. Calculation of variable-base degree-days and degree-nights from monthly average temperatures

    Microsoft Academic Search

    R. Sonderegger; P. Cleary; B. Dickinson

    1985-01-01

    The Computerized Instrumented Residential Audit (CIRA), a micro-computer building energy analysis program developed at Lawrence Berkeley Laboratory, uses a monthly variable-base degree-day method to calculate heating and cooling loads. The method's unique feature is its ability to model thermostat setbacks and storage of solar gain. The program accomplishes this by dividing each day into two periods, ''average day'' (8 a.m.

  7. Environmental, behavioral, and habitat variables influencing body temperature in radio-tagged bullsnakes, Pituophis catenifer sayi

    Microsoft Academic Search

    J. M. Kapfer; M. J. Pauers; D. M. Reineke; J. R. Coggins; R. Hay

    2008-01-01

    Studies regarding the thermal ecology of snakes are important to understanding their life histories. Yet, little is known about the thermal ecology of the North American genus Pituophis, which includes the bullsnake (Pituophis catenifer sayi). In an attempt to determine which independent variables significantly affected the thermal ecology of free-ranging bullsnakes, we tracked 12–19 radio-tagged individuals weekly from 2003 to

  8. Variability in water properties and predictability of sea surface temperature along Sanriku coast, Japan

    NASA Astrophysics Data System (ADS)

    Wagawa, Taku; Kuroda, Hiroshi; Ito, Shin-ichi; Kakehi, Shigeho; Yamanome, Takeshi; Tanaka, Kazushi; Endoh, Yuki; Kaga, Shinnosuke

    2015-07-01

    We investigated the main controlling factors and predictability of extreme sea surface temperature changes along the Sanriku coast (the east coast of the northern part of Japan's main island). We analyzed distributions of water properties and flow fields via intensive observations using a conductivity-temperature-depth profiler and a coastal water-temperature monitoring system from January 1998 to December 2012. Satellite altimetry and tide gauge data were also analyzed to investigate more widespread horizontal and temporal variation of the sea surface flow field. Anomalous temperature events (2 °C lower and higher than climatological monthly values) were observed in winter 2006 and fall 2010 and 2012 along the Sanriku coast. In winter (fall) 2006 (2010, 2012), we observed both unusually thick and wide cold/fresh (warm/saline) waters, corresponding to the Oyashio (Tsugaru Warm Current) waters. At that time, sea surface velocities of the Oyashio (Tsugaru Warm Current) along the Hokkaido coast (Tsugaru Strait) were also high. We propose new methods for predicting extreme temperature changes a few months in advance, based on current observations.

  9. Biological variability of fecal calprotectin in patients referred for colonoscopy without colonic inflammation or neoplasm

    Microsoft Academic Search

    Einar Husebye; Hege Tøn; Berit Johne

    2001-01-01

    OBJECTIVE:Fecal calprotectin concentration in stool has recently been proposed as a marker of colonic neoplasm and inflammation, but the intraindividual day-to-day variability has so far received little attention.The present study was undertaken to determine the biological variability of fecal calprotectin in patients referred for colonoscopy.METHODS:A prospective design was applied. In each of 14 consecutive patients submitted for colonoscopy, eight stool

  10. European Temperature Variability and Climate Forcing Over The Last 500 Years

    NASA Astrophysics Data System (ADS)

    Luterbacher, J.; Wanner, H.; Dietrich, D.; Friedli, T. K.

    We present seasonal temperature reconstructions back to 1500 for the European land areas (30W-40E; 35N-70N) on a dense 0.5x0.5 latitude by longitude grid. The reconstructions were developed using PC regression analysis based on the combina- tion of early instrumental station series of temperature and pressure and proxy data from Eurasian sites. The statistical relationships were derived over the 1901-1995 in- strumental period (New et al. 2000) and applied to the pre-1900 data. The reliability of the reconstruction and the time-dependent uncertainty ranges about the estimates are discussed. We derived a high precision winter (DJF), summer (JJA) and annual (J-D) mean Eu- ropean temperature time series from 1500-1998 through averaging of all the 5100 land gridpoints. We found several cold relapses and warm intervals on the decadal timescale, on which shorter-period quasi-oscillatory behaviour was superimposed. Warmer European winters were experienced in the first third of the 16th century, at the beginning of the 17th century and generally in the 20th century. The warmest decade was 1989-1998. Cooler winter conditions were found in the second part of the 16th century, during the Maunder Minimum and in most parts of the 19th century. The coldest decades in winter temperatures were 1586-1595 and the 1690s with 1.5C lower values compared to the 1961-1990 mean. Warm summers were observed from around 1530 to 1570, from the 1750s to the early 19th century, around 1950 and at the end of the 20th century. 1789-1798 and the 1990s were the warmest decades in summer temperatures. Cooler summer periods were prevalent from the 1570s to the beginning of the 17th century, in the middle of the 18th century and at the turn of the 20th century. The summers from 1902-1916 were among the coldest over the last 500 years. The low pass filtered timeseries of the annually averaged temperatures from 1500- 1950 were mainly below the 1961-1990 average. The yearly mean European tempera- ture are partly in agreement with Northern Hemispheric temperature variations (Mann et al. 1998). Finally, the statistical relationship between European annual temperature and recent estimates of climate forcing time series (Robertson et al. 2001) are presented.

  11. Variable temperature optoacoustic studies of 4f-states of neodymium in oxide phases

    SciTech Connect

    Beitz, J.V.; Hinaus, B.M. [Argonne National Lab., IL (United States); Huang, Jin [Wisconsin Univ., Madison, WI (United States). Dept. of Physics and Astronomy

    1993-09-01

    An apparatus for recording high sensitivity photoacoustic spectra from strongly light scattering samples has been constructed and tested at temperatures from 4 to 295K. The apparatus is suitable for use with air- or moisture-sensitive samples or radioactive samples requiring containment. Unlike an earlier ambient temperature photoacoustic study on Nd{sub 2}O{sub 3}, the photoacoustic bands observed from high purity Nd{sub 2}O{sub 3} in the present work agree well with the Stark components of 4f states of Nd{sup 3+} in A-type Nd{sub 2}O{sub 3} as assigned by Caro, Derouet, and Beaury.

  12. Higher temperature variability increases the impact of Batrachochytrium dendrobatidis and shifts interspecific interactions in tadpole mesocosms

    PubMed Central

    Hamilton, Phineas T; Richardson, Jean ML; Govindarajulu, Purnima; Anholt, Bradley R

    2012-01-01

    The emergence of amphibian chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd) has led to the decline and extinction of numerous amphibian species. Multiple studies have observed links between climatic factors and amphibian declines apparently caused by Bd. Using outdoor experimental mesocosms, we tested the response of red-legged frog (Rana aurora) tadpoles to increased variation in temperature, a component of climate linked to amphibian declines, and Bd exposure. We included tadpoles of a sympatric competitor species, Pacific chorus frog (Pseudacris regilla), in a fully factorial design to test the effects of Bd and temperature on interspecific interactions. We found that higher variation in temperature had numerous effects in mesocosms, including interacting with Bd presence to decrease the condition of R. aurora, shifting the relative performance of competing P. regilla and R. aurora, and accelerating the development of P. regilla relative to R. aurora. Our results demonstrate that increased variation in temperature can affect amphibians in multiple ways that will be contingent on ecological context, including the presence of Bd and competing species. PMID:23145331

  13. Room Temperature Control During Season Switchover with Single Duct Variable Air Volume System Without Reheat

    E-print Network

    Liu, C.; Deng, S.; Claridge, D. E.; Turner, W. D.; Bruner, H.

    2003-01-01

    of VAV boxes to maintain room temperature at their setpoints. The thermostat action is switched from direct acting (DA) to reverse acting (RA) when the season changes from fall to winter and vice versa from winter to spring, based on the out side air...

  14. Soil variability effects on canopy temperature in a limited irrigation experiment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Canopy temperature was monitored on a continuous basis in a limited irrigation maize experiment, with 12 separate irrigation treatments and 4 replicates of each treatment. Soil electroconductivity (EC) was measured and mapped to quantify variation in soil texture throughout the plots, and was correl...

  15. Room Temperature Control During Season Switchover with Single Duct Variable Air Volume System Without Reheat 

    E-print Network

    Liu, C.; Deng, S.; Claridge, D. E.; Turner, W. D.; Bruner, H.

    2003-01-01

    of VAV boxes to maintain room temperature at their setpoints. The thermostat action is switched from direct acting (DA) to reverse acting (RA) when the season changes from fall to winter and vice versa from winter to spring, based on the out side air...

  16. Solar variability effect on ion temperature observed by ROCSAT-1 satellite

    Microsoft Academic Search

    C. K. Chao; S. Y. Su; H. C. Yeh

    2006-01-01

    Ion temperature has been measured with the Ionospheric Plasma and Electrodynamics Instrument IPEI onboard the first satellite of Republic of China ROCSAT-1 at 600 km altitude for 5 3 years Most data collections fall into a range of solar flux between 100 and 220 and are sufficient to identify their correlations with the solar cycle In most regions the data

  17. A CLIMATOLOGY OF TEMPERATURE AND PRECIPITATION VARIABILITY IN THE UNITED STATES

    EPA Science Inventory

    This paper examines the seasonal and variance and standardized range for temperature and the seasonal end annual coefficient of variation and normalized standardized range for precipitation, on a climatic division level for the contiguous United States for the period 1895 to 1985...

  18. Monthly temperature, salinity, and transport variability of the Bering Strait through flow

    Microsoft Academic Search

    Rebecca A. Woodgate; Knut Aagaard; Thomas J. Weingartner

    2005-01-01

    The Bering Strait through flow is important for the Chukchi Sea and the Arctic and Atlantic oceans. A realistic assessment of through flow properties is also necessary for validation and boundary conditions of high-resolution ocean models. From 14 years of moored measurements, we construct a monthly climatology of temperature, salinity and transport. The strong seasonality in all properties (?31.9 to

  19. MONTHLY TEMPERATURE, SALINITY AND TRANSPORT VARIABILITY OF THE BERING STRAIT THROUGHFLOW

    Microsoft Academic Search

    Rebecca A. Woodgate; Knut Aagaard

    The Bering Strait throughflow is important for the Chukchi Sea and the Arctic and Atlantic oceans. A realistic assessment of throughflow properties is also necessary for validation and boundary conditions of high resolution ocean models. From 14 years of moored measurements, we construct a monthly climatology of temperature, salinity and transport. The strong seasonality in all properties (~ 31.9 to

  20. Temperature and salinity variability in the exit passages of the Indonesian Throughflow

    Microsoft Academic Search

    Janet Sprintall; James T. Potemra; Susan L. Hautala; Nancy A. Bray; Wahyu W. Pandoe

    2003-01-01

    The Indonesian Throughflow was monitored from December 1995 until May 1999 in the five major exit passages of the Lesser Sunda Islands, as it flows from the Indonesian interior seas into the southeast Indian Ocean. The monitoring array included pairs of shallow pressure gauges at each side of the straits, equipped with temperature and salinity sensors. As in the inferred

  1. Intra- to Multi-Decadal Temperature Variability over the Continental United States: 1896-2012

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Optimal Ranking Regime (ORR) method was used to identify intra- to multi-decadal (IMD) time windows containing significant ranking sequences in U.S. climate division temperature data. The simplicity of the ORR procedure’s output – a time series’ most significant non-overlapping periods of high o...

  2. Membrane stability of winter wheat plants exposed to subzero temperatures for variable lengths of time

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The ability to survive episodes of subfreezing temperature is essential to winter wheat. Fully cold-acclimated plants of six lines of winter wheat were exposed to -12, -14, -16 or -18° C, four 1-5 hours. Electrolyte leakage and plant survival were used to assess damage to the plants. Plants exposed ...

  3. A variable temperature mechanical analysis of ZDDP-derived antiwear films formed on 52100 steel

    Microsoft Academic Search

    Gavin Pereira; David Munoz-Paniagua; Andreas Lachenwitzer; Masoud Kasrai; Peter R. Norton; T. Weston Capehart; Thomas A. Perry; Yang-Tse Cheng

    2007-01-01

    The nanomechanical properties of antiwear films formed from zinc dialkyl-dithiophosphates (ZDDPs) on steel have been studied by nanoindentation techniques as a function of temperature. X-ray absorption P K- and L- near edge structure (XANES) spectroscopy has shown that films prepared from oils containing ZDDPs on 52100 steel (pin on flat coupons) consist primarily of medium chain polyphosphates with sulphur (S

  4. Late Holocene air temperature variability reconstructed from the sediments of Laguna Escondida, Patagonia, Chile (4530S)

    E-print Network

    Wehrli, Bernhard

    in Northern Chilean Patagonia, Lago Castor (45°36S, 71°47W) and Laguna Escondida (45°31S, 71°49W). Radiometric) and c. 1900 BC (Lago Castor). Both lakes show similarities and repro- ducibility in sedimentation rate signal and correlation with annual temperature reanalysis data (calibration 1900­2006 AD; Lago Castor r=0

  5. Multiscale Variabilities in Global Sea Surface Temperatures and Their Relationships with Tropospheric Climate Patterns

    Microsoft Academic Search

    David B. Enfield; Alberto M. Mestas-Nuñez

    1999-01-01

    El Nino-Southern Oscillation (ENSO) is a global phenomenon with significant phase propagation within and between basins. This is captured and described in the first mode of a complex empirical orthogonal function (CEOF) analysis of sea surface temperature anomaly (SSTA) from the midnineteenth century through 1991. The global ENSO from the SSTA data, plus a linear trend everywhere, are subsequently removed

  6. New variable low-temperature scanning tunneling microscope for use in ultrahigh vacuum

    E-print Network

    and C. K. Shih Department of Physics, University of Texas, Austin, Texas 78712 (Received 11 July 1994 attach to the top flange. An adjustable cold shroud surrounds the STM stage for radiation shielding while.`l II. INSTRUMENT DESCRlPTlON Shown in Fig. l(a) is a cross-cut sideview of the low- temperature STM

  7. Combined effects of chemical and temperature stress on Chironomus riparius populations with differing genetic variability

    Microsoft Academic Search

    Matthias Oetken; Lucas S. Jagodzinski; Christian Vogt; Adrienne Jochum; Jörg Oehlmann

    2009-01-01

    Exposure to pollutants under multiple environmental stressors (e.g., climate change and global warming) and the genetic diversity of populations are suspected to have serious impacts on populations and ecosystems but have only rarely been analysed. In the present study, we investigated the effects of the biocide tributyltin (TBT) within a temperature gradient (17, 20 and 23°C) on life history parameters

  8. Spatial and temporal variability of urban tree canopy temperature during summer 2010 in Berlin, Germany

    NASA Astrophysics Data System (ADS)

    Meier, Fred; Scherer, Dieter

    2012-12-01

    Trees form a significant part of the urban vegetation. Their meteorological and climatological effects at all scales in urban environments make them a flexible tool for creating a landscape oriented to the needs of an urban dweller. This study aims at quantifying the spatio-temporal patterns of canopy temperature ( T C) and canopy-to-air temperature difference (? T C) in relation to meteorological conditions and tree-specific (physiological) and urban site-specific characteristics. We observed T C and ? T C of 67 urban trees (18 species) using a high-resolution thermal-infrared (TIR) camera and meteorological measurements in the city of Berlin, Germany. TIR images were recorded at 1-min intervals over a period of 2 months from 1st July to 31st August 2010. The results showed that ? T C depends on tree species, leaf size and fraction of impervious surfaces. Average canopy temperature was nearly equal to air temperature. Species-specific maximum ?T C varied between 1.9 ± 0.3 K ( Populus nigra), 2.9 ± 0.3 K ( Quercus robur), 3.2 ± 0.5 K ( Fagus sylvatica), 3.9 ± 1.0 K ( Platanus acerifolia), 4.6 ± 0.2 K ( Acer pseudoplatanus), 5.0 ± 0.5 K ( A. platanoides) and 5.6 ± 1.1 K ( A. campestre). We analysed ? T C for a hot and dry period (A) and a warm and wet period (B). The range of species-specific ?T C at noon was nearly equal, i.e. 4.4 K for period A and 4.2 K for period B. Trees surrounded by high fraction of impervious surfaces showed consistently higher ? T C. Knowledge of species-specific canopy temperature and the impacts of urban structures are essential in order to optimise the benefits from trees in cities. However, comprehensive evaluation and optimisation should take the full range of climatological effects into account.

  9. On the possibility of forecasting the long-term air temperature variability that determines the hydrophysical structure and ecology of the Black Sea waters

    Microsoft Academic Search

    V. B. Titov; M. T. Savin

    2007-01-01

    Periods and amplitudes of long-term temperature fluctuations were obtained using the methods of spectral analysis and filtration\\u000a of secular time series of the air temperature at 13 hydrometeorological stations in the Black Sea region. The prognostic calculations\\u000a of the long-term air temperature variability are based on the results of processing of time series. The calculations of the\\u000a air temperature agree

  10. Spatiotemporal variability of increasing temperature impacts on grassland vegetation along an elevation transect in the Alps

    NASA Astrophysics Data System (ADS)

    Niedrist, Georg; Obojes, Nikolaus; Bertoldi, Giacomo; Della Chiesa, Stefano; Tasser, Erich; Tappeiner, Ulrike

    2013-04-01

    Different manipulative approaches have been developed to study and quantify impacts of temperature increase on grassland ecosystems. Many of them share the problem of unwanted effects on the surrounding microclimatic conditions. Transplantation of grassland mesocosms along elevation gradients can be a realistic alternative, although with some restrictions. Here we present 3 years of data from a double-transplant-experiment, were 70*70*20cm grassland turves were transplanted at two elevations from 2000m to 1500m a.s.l. and from 1500m to 1000m a.s.l. respectively, along an inner-alpine elevation gradient in the Vinschgau Valley (South Tyrol, I). All donor and receiving sites are comparable regarding land use (meadows), soil conditions or exposition and are located within a few km's distance ensuring comparable weather conditions apart from the intended air temperature (0.54°K/100m) and annual precipitation (20mm/100m) lapse rate. Phytodiversity and above ground net primary production (ANPP) of the transplanted mesocosms were assessed and compared with locally transplanted monoliths of the respective donor site. Furthermore, growth dynamics was continuously observed throughout the vegetation season with a non-destructive method based on measurement of light (photosynthetic active radiation) extinction within the canopy. After 3 years no significant changes in absolute species numbers has been detected at all, whereas slight variations have been observed regarding species composition. Those shifts could be differentiated both to transplantation artifacts and effects of the elevated temperature. Total aboveground phytomass, unsurprisingly, showed higher values on transplanted (lower) mesocosms, however: data from single cuts and growth rate analysis reveal differing effects between the two transplantation steps as well as over the course of the vegetation period. Transplanted plots from 2000m to 1500m showed continuously higher productivity from spring to autumn, whereas on the lower transplants (from 1500m to 1000m) during summer months the temperature benefit gets balanced by higher evapotranspiration rates, resulting in more frequent drought stress. Summarizing, gained experiences confirm well-designed transplant approach to be an interesting alternative for mid- to longterm simulations of future climate conditions in grassland ecosystems. Furthermore, results indicate that the impact of increasing temperatures in the studied grassland highly depends on elevation and acts rather by a prolongation of the vegetation period than by elevated summer temperatures.

  11. Global climatology and variability of potential new production estimated from remote sensing of sea-surface temperature

    NASA Technical Reports Server (NTRS)

    Dugdale, Richard C.; Wilkerson, Frances P.

    1995-01-01

    During this project we have collected numerous shipboard data-bases of oceanic nitrate and silicate versus temperature for both equatorial and coastal upwelling regions. These cruises all have accompanying N-15 measurements of new production. The inverse relationships between nutrients and temperatures have been determined and are being used to obtain surface nutrient fields from sea surface temperatures measured remotely by satellite borne sensors- i.e. AVHRR data from NOAA satellites contained in the MCSST data set for the world ocean provided by the University of Miami. The images and data derived from space in this way show the strong seasonal fluctuations and interannual el Nino fluctuations of the nitrate field. the nitrate data has been used to make estimates of new production for the equatorial pacific which are compared with shipboard measurements when available. The importance of silicate as a nutrient driving new production and the ratio of nitrate to silicate has been discovered to be crucial to better understand the causes of new production variability, so we have added these parameters to our study and have begun to make estimates of these for the equatorial Pacific, derived from the weekly averaged sea surface temperatures (SSTs).

  12. Constraints from the CMB temperature and other common observational data sets on variable dark energy density models

    NASA Astrophysics Data System (ADS)

    Jetzer, Philippe; Tortora, Crescenzo

    2011-08-01

    The thermodynamic and dynamical properties of a variable dark energy model with density scaling as ?x?(1+z)m, z being the redshift, are discussed following the outline of Jetzer et al. [P. Jetzer, D. Puy, M. Signore, and C. Tortora, Gen. Relativ. Gravit. 43, 1083 (2011).GRGVA80001-770110.1007/s10714-010-1091-4]. These kinds of models are proven to lead to the creation/disruption of matter and radiation, which affect the cosmic evolution of both matter and radiation components in the Universe. In particular, we have concentrated on the temperature-redshift relation of radiation, which has been constrained using a very recent collection of cosmic microwave background (CMB) temperature measurements up to z˜3. For the first time, we have combined this observational probe with a set of independent measurements (Supernovae Ia distance moduli, CMB anisotropy, large-scale structure and observational data for the Hubble parameter), which are commonly adopted to constrain dark energy models. We find that, within the uncertainties, the model is indistinguishable from a cosmological constant which does not exchange any particles with other components. Anyway, while temperature measurements and Supernovae Ia tend to predict slightly decaying models, the contrary happens if CMB data are included. Future observations, in particular, measurements of CMB temperature at large redshift, will allow to give firmer bounds on the effective equation of state parameter weff of this kind of dark energy model.

  13. The vertical variability of hyporheic fluxes inferred from riverbed temperature data

    NASA Astrophysics Data System (ADS)

    Cranswick, Roger H.; Cook, Peter G.; Shanafield, Margaret; Lamontagne, Sebastien

    2014-05-01

    We present detailed profiles of vertical water flux from the surface to 1.2 m beneath the Haughton River in the tropical northeast of Australia. A 1-D numerical model is used to estimate vertical flux based on raw temperature time series observations from within downwelling, upwelling, neutral, and convergent sections of the hyporheic zone. A Monte Carlo analysis is used to derive error bounds for the fluxes based on temperature measurement error and uncertainty in effective thermal diffusivity. Vertical fluxes ranged from 5.7 m d-1 (downward) to -0.2 m d-1 (upward) with the lowest relative errors for values between 0.3 and 6 m d-1. Our 1-D approach provides a useful alternative to 1-D analytical and other solutions because it does not incorporate errors associated with simplified boundary conditions or assumptions of purely vertical flow, hydraulic parameter values, or hydraulic conditions. To validate the ability of this 1-D approach to represent the vertical fluxes of 2-D flow fields, we compare our model with two simple 2-D flow fields using a commercial numerical model. These comparisons showed that: (1) the 1-D vertical flux was equivalent to the mean vertical component of flux irrespective of a changing horizontal flux; and (2) the subsurface temperature data inherently has a "spatial footprint" when the vertical flux profiles vary spatially. Thus, the mean vertical flux within a 2-D flow field can be estimated accurately without requiring the flow to be purely vertical. The temperature-derived 1-D vertical flux represents the integrated vertical component of flux along the flow path intersecting the observation point. This article was corrected on 6 JUN 2014. See the end of the full text for details.

  14. Mechanisms and Distribution of Ion Channels in Retinal Ganglion Cells: Using Temperature as an Independent Variable

    PubMed Central

    Cohen, Ethan D.; Newman, Eric A.

    2010-01-01

    Trains of action potentials of rat and cat retinal ganglion cells (RGCs) were recorded intracellularly across a temperature range of 7–37°C. Phase plots of the experimental impulse trains were precision fit using multicompartment simulations of anatomically reconstructed rat and cat RGCs. Action potential excitation was simulated with a “Five-channel model” [Na, K(delayed rectifier), Ca, K(A), and K(Ca-activated) channels] and the nonspace-clamped condition of the whole cell recording was exploited to determine the channels' distribution on the dendrites, soma, and proximal axon. At each temperature, optimal phase-plot fits for RGCs occurred with the same unique channel distribution. The “waveform” of the electrotonic current was found to be temperature dependent, which reflected the shape changes in the experimental action potentials and confirmed the channel distributions. The distributions are cell-type specific and adequate for soma and dendritic excitation with a safety margin. The highest Na-channel density was found on an axonal segment some 50–130 ?m distal to the soma, as determined from the temperature-dependent “initial segment–somadendritic (IS-SD) break.” The voltage dependence of the gating rate constants remains invariant between 7 and 23°C and between 30 and 37°C, but undergoes a transition between 23 and 30°C. Both gating-kinetic and ion-permeability Q10s remain virtually constant between 23 and 37°C (kinetic Q10s = 1.9–1.95; permeability Q10s = 1.49–1.64). The Q10s systematically increase for T <23°C (kinetic Q10 = 8 at T = 8°C). The Na channels were consistently “sleepy” (non-Arrhenius) for T <8°C, with a loss of spiking for T <7°C. PMID:20053849

  15. Changes in fossil-fuel carbon emissions in response to interannual and interdecadal temperature variability

    Microsoft Academic Search

    WeiHong Qian; Bo Lu; HaoYuan Liang

    2011-01-01

    Relationships on interannual and interdecadal timescales among global mean air temperature, CO2 concentrations and fossil-fuel carbon emissions in four major developed countries (the United States, the United Kingdom,\\u000a France, and Germany) were analyzed. On an interannual timescale, the United States fossil-fuel carbon emissions tend to increase\\u000a during cold winters and decrease during warm winters, which is opposite to the situation

  16. Arctic climate change: observed and modelled temperature and sea-ice variability

    Microsoft Academic Search

    Ola M. Johannessen; Lennart Bengtsson; Martin W. Miles; Svetlana I. Kuzmina; Vladimir A. Semenov; Genrikh V. Alekseev; Andrei P. Nagurnyi; Victor F. Zakharov; Leonid P. Bobylev; Lasse H. Pettersson; Klaus Hasselmann; Howard P. Cattle

    2004-01-01

    Changes apparent in the arctic climate system in recent years require evaluation in a century-scale perspective in order to assess the Arctic's response to increasing anthropogenic greenhouse-gas forcing. Here, a new set of century- and multidecadal-scale observational data of surface air temperature (SAT) and sea ice is used in combination with ECHAM4 and HadCM3 coupled atmosphere ice ocean global model

  17. Seasonal and interannual variability in temperature, chlorophyll and macronutrients in northern Marguerite Bay, Antarctica

    Microsoft Academic Search

    Andrew Clarke; Michael P. Meredith; Margaret I. Wallace; Mark A. Brandon; David N. Thomas

    2008-01-01

    We report data from the first 8 years of oceanographic monitoring in Ryder Bay, northern Marguerite Bay, Antarctica. These data form the oceanographic component of the Rothera Oceanographic and Biological Time-Series (RaTS) project. When weather and ice permit, the RaTS station is occupied every 5 days in summer and weekly in winter. Observations comprise a conductivity–temperature–depth (CTD) cast to 500m

  18. Sea Ice and Ice Temperature Variability as Observed by Microwave and Infrared Satellite Data

    NASA Technical Reports Server (NTRS)

    Comiso, Josefino C.; Koblinsky, Chester J. (Technical Monitor)

    2001-01-01

    Recent reports of a retreating and thinning sea ice cover in the Arctic have pointed to a strong suggestion of significant warming in the polar regions. It is especially important to understand what these reports mean in light of the observed global warning and because the polar regions are expected to be most sensitive to changes in climate. To gain insight into this phenomenon, co-registered ice concentrations and surface temperatures derived from two decades of satellite microwave and infrared data have been processed and analyzed. While observations from meteorological stations indicate consistent surface warming in both regions during the last fifty years, the last 20 years of the same data set show warming in the Arctic but a slight cooling in the Antarctic. These results are consistent with the retreat in the Arctic ice cover and the advance in the Antarctic ice cover as revealed by historical satellite passive microwave data. Surface temperatures derived from satellite infrared data are shown to be consistent within 3 K with surface temperature data from the limited number of stations. While not as accurate, the former provides spatially detailed changes over the twenty year period. In the Arctic, for example, much of the warming occurred in the Beaufort Sea and the North American region in 1998 while slight cooling actually happened in parts of the Laptev Sea and Northern Siberia during the same time period. Big warming anomalies are also observed during the last five years but a periodic cycle of about ten years is apparent suggesting a possible influence of the North Atlantic Oscillation. In the Antarctic, large interannual and seasonal changes are also observed in the circumpolar ice cover with regional changes showing good coherence with surface temperature anomalies. However, a mode 3 is observed to be more dominant than the mode 2 wave reported in the literature. Some of these spatial and temporal changes appear to be influenced by the Antarctic Circumpolar Wave (ACW) and changes in coastal polynya activities.

  19. Arctic Temperature and Moisture Variability Associated with the Pliocene M2 Glacial Event from Lake El'gygytgyn, NE Russia

    NASA Astrophysics Data System (ADS)

    Salacup, J. M.; Castañeda, I. S.; Brigham-Grette, J.

    2014-12-01

    The early Late Pliocene (3.6-3.0 Ma) is the last time atmospheric CO2 concentrations equaled today's values (~400 ppm). Despite this, and the warmer than modern climate it fostered, this period experienced an intense global glaciation during marine isotope stage (MIS) M2 (~3.3 Ma). Constraints imposed by the estimated sea level drop associated with this event suggest ice growth was not isolated to Antarctica, as had previously been the case, but that ice grew in high northern latitudes as well. M2 is unique during the Pliocene and is likely the first attempt of Northern Hemisphere ice sheets to grow into those experienced during Pleistocene ice ages. However, the effects of MIS M2, and any attendant Northern Hemisphere ice sheets, on Arctic terrestrial temperature and hydrology are not well understood. Here we present and compare results from the biomarker-based MBT/CBT paleotemperature proxy with ?Dleaf wax results, sensitive to both temperature hydrology, from Lake El'gygytgyn (NE Russia) in an attempt to isolate and characterize variability in both air temperature and moisture source/availability. We compare our results with more coarsely resolved preexisting pollen-based temperature and moisture reconstructions. Our temperature reconstruction is, as far as we know, the highest resolution terrestrial record of this dramatic global cooling event. It implies a ~6°C cooling circa 3.29 Ma was accomplished in two steps before a rebound of ~7°C into the start of the mid-Pliocene Warm Period. Removal of the temperature effect from M2 ?Dleaf wax profiles using our MBT/CBT results provide insight into changes in local hydrology during this event that are compared with pollen-based estimates of minimum, maximum, and mean annual precipitation in order to discuss changes in amount and seasonality of moisture delivery to Lake El'gygytgyn (NE Russia) during the expansion of Northern Hemisphere ice sheets.

  20. Ocean rises are products of variable mantle composition, temperature and focused melting

    NASA Astrophysics Data System (ADS)

    Dick, Henry J. B.; Zhou, Huaiyang

    2015-01-01

    Ocean ridges, where Earth's tectonic plates are pulled apart, range from more than 5-km depth in the Arctic to 750 m above sea level in Iceland. This huge relief is generally attributed to mantle plumes underlying mantle hotspots--areas of voluminous volcanism marked by ocean islands. The plumes are thought to feed the mantle beneath adjacent ocean ridges. This process results in thickened crust and ridge elevation to form ocean rises. The composition of mid-ocean ridge basalt, a direct function of mantle composition and temperature, varies systematically along ocean rises, but in a unique way for each different rise. Here we use thermodynamic calculations of melt-evolution pathways to show that variations in both mantle temperature and source composition are required to explain the chemical make-up of rise basalts. Thus, lateral gradients in mantle temperature cannot be uniquely determined from basalt chemistry, and ocean rises can be supported by chemically buoyant mantle or by robust mantle plumes. Our calculations also indicate that melt is conserved and focused by percolative flow towards the overlying ridge, progressively interacting with the mantle to shallow depth. We conclude that most mantle melting occurs by an overlooked mechanism, focused melting, whereas fractional melting is a secondary process that is important largely at shallow depth.

  1. Trap density of states in n-channel organic transistors: variable temperature characteristics and band transport

    SciTech Connect

    Cho, Joung-min, E-mail: cho.j.ad@m.titech.ac.jp; Akiyama, Yuto; Kakinuma, Tomoyuki [Department of Organic and Polymeric Materials, Tokyo Institute of Technology, O-okayama, Tokyo 152-8552 (Japan)] [Department of Organic and Polymeric Materials, Tokyo Institute of Technology, O-okayama, Tokyo 152-8552 (Japan); Mori, Takehiko [Department of Organic and Polymeric Materials, Tokyo Institute of Technology, O-okayama, Tokyo 152-8552 (Japan) [Department of Organic and Polymeric Materials, Tokyo Institute of Technology, O-okayama, Tokyo 152-8552 (Japan); ACT-C, JST, Honcho, Kawaguchi, Saitama 332-0012 (Japan)

    2013-10-15

    We have investigated trap density of states (trap DOS) in n-channel organic field-effect transistors based on N,N?’-bis(cyclohexyl)naphthalene diimide (Cy-NDI) and dimethyldicyanoquinonediimine (DMDCNQI). A new method is proposed to extract trap DOS from the Arrhenius plot of the temperature-dependent transconductance. Double exponential trap DOS are observed, in which Cy-NDI has considerable deep states, by contrast, DMDCNQI has substantial tail states. In addition, numerical simulation of the transistor characteristics has been conducted by assuming an exponential trap distribution and the interface approximation. Temperature dependence of transfer characteristics are well reproduced only using several parameters, and the trap DOS obtained from the simulated characteristics are in good agreement with the assumed trap DOS, indicating that our analysis is self-consistent. Although the experimentally obtained Meyer-Neldel temperature is related to the trap distribution width, the simulation satisfies the Meyer-Neldel rule only very phenomenologically. The simulation also reveals that the subthreshold swing is not always a good indicator of the total trap amount, because it also largely depends on the trap distribution width. Finally, band transport is explored from the simulation having a small number of traps. A crossing point of the transfer curves and negative activation energy above a certain gate voltage are observed in the simulated characteristics, where the critical V{sub G} above which band transport is realized is determined by the sum of the trapped and free charge states below the conduction band edge.

  2. Dynamics and thermodynamics of crystalline polymorphs: ?-glycine, analysis of variable-temperature atomic displacement parameters.

    PubMed

    Aree, Thammarat; Bürgi, Hans-Beat; Capelli, Silvia C

    2012-08-01

    Multitemperature synchrotron diffraction data to 0.5 Å resolution in the temperature range 10-298 K and neutron data at 18 K of the ?-glycine polymorph have been collected at the KEK photon factory (PF), SPring-8 and the Institut Laue Langevin (ILL) for the study of molecular motion in the crystal and of the associated thermodynamic functions. Atomic displacement parameters (ADPs) of non-H atoms are obtained from refinements based on nonspherical atomic scattering factors (invariom model) to minimize correlation between parameters describing thermal motion and valence electron density. The ADPs in the temperature range 50-298 K from SPring-8 connect smoothly with those from neutron diffraction at 18 K and 288-323 K. The combined ADPs from both sources covering the temperature range 18-323 K are used for a normal-mode analysis in the molecular mean field approximation. The lattice vibration frequencies from the ADP analysis and the internal vibration frequencies from an ONIOM (B3LYP/6-311+G(2d,p):PM3) calculation together with the Einstein, Debye, and Nernst-Lindemann models of heat capacity are used to calculate Cp, Hvib, and Svib values that are in good agreement with those from calorimetry. PMID:22746958

  3. The combined influences of variable thermal conductivity, temperature- and pressure-dependent viscosity and core–mantle coupling on thermal evolution

    Microsoft Academic Search

    A. P. van den Berg; E. S. G. Rainey; D. A. Yuen

    2005-01-01

    Most convection studies of thermal history have not considered explicitly the thermal interaction between the mantle flow and the core. We have investigated the influences of variable thermal conductivity and variable viscosity (temperature- and pressure-dependent) on the boundary layer and thermal characteristics of the D? layer, and the evolution of the thermo-mechanical profiles of horizontally averaged viscosity and thermal conductivity.

  4. Impact of Interdecadal Sea Level and Sea Surface Temperature Variability on Primary Productivity and Harmful Algal Blooms in Southern California

    NASA Astrophysics Data System (ADS)

    Perry, K. L.

    2014-12-01

    Harmful Algal Blooms (HABs) are increasing in frequency and intensity on global, regional and local scales. Although climate change has been suggested as one of the key factors, very few interdecadal studies comparing HABs to low frequency physical forcing have been performed. Interannual to interdecadal variability in sea level and sea surface temperature along the Southern California Coast have been shown to have high correlation with the El Nino-La Nina signal. This is important in the study of phytoplankton, because abnormally low sea level corresponds to increased sea surface nutrient concentrations in this region. The California current is stronger during these times, and the higher nutrient water found to the north is advected southward. We have determined that primary productivity is most highly correlated with interdecadal sea level variability derived from tide gage data at a lag of approximately 2 months. This is consistent with previous zooplankton studies. In preparation for a potential El Nino event, we have expanded our analysis to include parameters such as sea surface temperature, salinity and nutrient concentrations from spaceborne and in situ instruments. We have also expanded our research to allow for analysis of several of the most prevalent HAB species. This work is the first step in our effort to create a model to predict and locate Southern California HAB events in the future.

  5. Interannual variability of precipitation over North America and its relationship to sea surface temperatures from GCM and RCM simulations

    NASA Astrophysics Data System (ADS)

    Fuentes-Franco, Ramon; Giorgi, Filippo; Coppola, Erika; Kucharski, Fred

    2015-04-01

    An ensemble of future climate projections performed with GCMs and RCMs is used to analyze changes in the relationship between sea surface temperature (SST) and inter-annual variability of precipitation over North America during winter (November to March). We analyze the influence of the interaction between the El Niño Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) on the precipitation over Mexico and North America. As in observations, GCM simulations reproduce reasonably well how PDO modulates ENSO teleconnections during the historical period, reproducing strong atmospheric and precipitation responses during constructive ENSO-PDO interference (El Niño and a positive PDO, or La Niña with negative PDO). Conversely, signals tend to be weak during destructive ENSO-PDO interference (El Niño with a negative PDO and La Niña with a positive PDO). An intensification of the PDO signal on SST anomalies in the future (2051-2100) compared to the historical simulations is found in the ensemble of models. Future warmer SST conditions produce a stronger response in precipitation to El Niño and positive PDO, thus, increasing the variability in the regions of North America with teleconnection (mainly over Norhtern Mexico, California and Southwest USA). This future change on interannual variability is in part due to a more important role of PDO on precipitation over these regions, compared to the historical simulations. RCM simulations generally confirm these conclusions, but the changes are more pronounced in the RCM than the GCM projections.

  6. Trends and variability of daily temperature extremes during 1960-2012 in the Yangtze River Basin, China

    NASA Astrophysics Data System (ADS)

    Guan, Yinghui; Zhang, Xunchang; Zheng, Fenli; Wang, Bin

    2015-01-01

    The variability of surface air temperature extremes has been the focus of attention during the past several decades, and may exert a great influence on the global hydrologic cycle and energy balance through thermal forcing. Based on daily minimum (TN) and maximum temperature (TX) observed by the China Meteorological Administration at 143 meteorological stations in the Yangtze River Basin (YRB), a suite of temperature indices recommended by the Expert Team on Climate Change Detection and Indices, with a primary focus on extreme events, were computed and analyzed for the period of 1960-2012 for this area. The results show widespread significant changes in all temperature indices associated with warming in the YRB during 1960-2012. On the whole, cold-related indices, i.e., cold nights, cold days, frost days, icing days and cold spell duration index significantly decreased by - 3.45, - 1.03, - 3.04, - 0.42 and - 1.6 days/decade, respectively. In contrast, warm-related indices such as warm nights, warm days, summer days, tropical nights and warm spell duration index significantly increased by 2.95, 1.71, 2.16, 1.05 and 0.73 days/decade. Minimum TN, maximum TN, minimum TX and maximum TX increased significantly by 0.42, 0.18, 0.19 and 0.14 °C/decade. Because of a faster increase in minimum temperature than maximum temperature, the diurnal temperature range (DTR) exhibited a significant decreasing trend of - 0.09 °C/decade for the whole YRB during 1960-2012. However, the decreasing trends all occurred in 1960-1985, while increasing trends though insignificant were found in all sub-regions and the whole YRB during 1986-2012. Geographically, stations in the eastern Tibet Plateau and northeastern YRB showed stronger trends in almost all temperature indices. Time series analysis indicated that the YRB was dominated by a general cooling trend before the mid-1980s, but a warming trend afterwards. In general, the overall warming in the YRB was mainly due to the warming in 1986-2012. Strong relationships between temperature trends and elevation were detected in this study. The warming rates increased with elevation when elevation is above 350 m, but decreased with elevation when elevation is below 350 m.

  7. Comet Halley - Spatial and temporal variability of the silicate emission feature

    NASA Astrophysics Data System (ADS)

    Ryan, E. V.; Campins, H.

    1991-02-01

    Narrow- and broadband photometry of Comet Halley covering the wavelength range 2-20 microns was obtained at the NASA Infrared Telescope Facility (IRTF) both preperihelion (UT 1986 January 17 and 18) and postperihelion (UT 1986 March 3-5). Strong features at 10 and 20 microns, indicative of silicate emission, were evident in the data. In addition to day-to-day variations in brightness at all wavelengths, changes were observed in the strength of the silicate emission feature on timescales as short as 3 hr. While the strength of the 10-micron feature varied with location in the coma, no such variability was observed in the shape of this emission feature, in agreement with higher spectral resolution observations (Campins and Ryan, 1989). Calculated color temperatures indicate that brightness and temperature do not correlate directly, i.e., brighter did not necessarily imply hotter dust grains. These observations are used to refine a relation between the color temperature of the dust and the heliocentric distance derived by Tokunaga et al. (1988).

  8. Role of the Indian Ocean sea surface temperature in shaping the natural variability in the flow of Nile River

    NASA Astrophysics Data System (ADS)

    Siam, Mohamed S.; Wang, Guiling; Demory, Marie-Estelle; Eltahir, Elfatih A. B.

    2014-08-01

    A significant fraction of the inter-annual variability in the Nile River flow is shaped by El Niño Southern Oscillation (ENSO). Here, we investigate a similar role for the Indian Ocean (IO) sea surface temperature (SST) in shaping the inter-annual variability of the Nile River flow. Using observations of global SST distribution and river flow in addition to atmospheric general circulation model sensitivity experiments, we show that North and Middle IO SSTs play a significant intermediate role in the teleconnection between ENSO and the Nile flow. Applying partial coherency analyses, we demonstrate that the connection between North and Middle IO SSTs and Nile flow is strongly coupled to ENSO. During El Niño events, SST in the North and Middle IO increases in response to the warming in the Tropical Eastern Pacific Ocean and forces a Gill-type circulation with enhanced westerly low-level flow over East Africa and the Western IO. This anomalous low-level flow enhances the low-level flux of air and moisture away from the Upper Blue Nile (UBN) basin resulting in reduction of rainfall and river flow. SSTs in the South IO also play a significant role in shaping the variability of the Nile flow that is independent from ENSO. A warming over the South IO, generates a cyclonic flow in the boundary layer, which reduces the cross-equatorial meridional transport of air and moisture towards the UBN basin, favoring a reduction in rainfall and river flow. This independence between the roles of ENSO and South IO SSTs allows for development of new combined indices of SSTs to explain the inter-annual variability of the Nile flow. The proposed teleconnections have important implications regarding mechanisms that shape the regional impacts of climate change over the Nile basin.

  9. Processes of 30-90 days sea surface temperature variability in the northern Indian Ocean during boreal summer

    NASA Astrophysics Data System (ADS)

    Vialard, J.; Jayakumar, A.; Gnanaseelan, C.; Lengaigne, M.; Sengupta, D.; Goswami, B. N.

    2012-05-01

    During summer, the northern Indian Ocean exhibits significant atmospheric intraseasonal variability associated with active and break phases of the monsoon in the 30-90 days band. In this paper, we investigate mechanisms of the Sea Surface Temperature (SST) signature of this atmospheric variability, using a combination of observational datasets and Ocean General Circulation Model sensitivity experiments. In addition to the previously-reported intraseasonal SST signature in the Bay of Bengal, observations show clear SST signals in the Arabian Sea related to the active/break cycle of the monsoon. As the atmospheric intraseasonal oscillation moves northward, SST variations appear first at the southern tip of India (day 0), then in the Somali upwelling region (day 10), northern Bay of Bengal (day 19) and finally in the Oman upwelling region (day 23). The Bay of Bengal and Oman signals are most clearly associated with the monsoon active/break index, whereas the relationship with signals near Somali upwelling and the southern tip of India is weaker. In agreement with previous studies, we find that heat flux variations drive most of the intraseasonal SST variability in the Bay of Bengal, both in our model (regression coefficient, 0.9, against ~0.25 for wind stress) and in observations (0.8 regression coefficient); ~60% of the heat flux variation is due do shortwave radiation and ~40% due to latent heat flux. On the other hand, both observations and model results indicate a prominent role of dynamical oceanic processes in the Arabian Sea. Wind-stress variations force about 70-100% of SST intraseasonal variations in the Arabian Sea, through modulation of oceanic processes (entrainment, mixing, Ekman pumping, lateral advection). Our ~100 km resolution model suggests that internal oceanic variability (i.e. eddies) contributes substantially to intraseasonal variability at small-scale in the Somali upwelling region, but does not contribute to large-scale intraseasonal SST variability due to its small spatial scale and random phase relation to the active-break monsoon cycle. The effect of oceanic eddies; however, remains to be explored at a higher spatial resolution.

  10. Seasonality of sporadic physical processes driving temperature and nutrient high-frequency variability in the coastal ocean off southeast Australia

    NASA Astrophysics Data System (ADS)

    Rossi, Vincent; Schaeffer, Amandine; Wood, Julie; Galibert, Guillaume; Morris, Brad; Sudre, Joel; Roughan, Moninya; Waite, Anya M.

    2014-01-01

    Physical processes forced by alongshore winds and currents are known to strongly influence the biogeochemistry of coastal waters. Combining in situ observations (moored platforms, hydrographic surveys) and satellite data (sea surface wind and sea surface height), we investigate the transient occurrence of wind-driven upwelling/downwelling and current-driven upwelling events off southeast Australia. Remote-sensed indices are developed and calibrated with multiannual time series of in situ temperature and current measurements at two shelf locations. Based on archives up to 10 years long, climatological analyses of these indices reveal various latitudinal regimes with respect to seasonality, magnitude, duration of events, and their driving mechanisms (wind or current). Generally, downwelling-favorable winds prevail in this region; however, we demonstrate that up to 10 wind-driven upwelling days per month occur during spring/summer at 28-33.5°S and up to 5 days in summer further south. Current-driven upwelling upstream of the East Australian Current separation zone (˜32°S) occurs twice as often as downstream. Using independent in situ data sets, we show that the response of the coastal ocean is consistent with our climatology of shelf processes: upwelling leads to a large range of temperatures and elevated nutrient concentrations on the shelf, maximized in the wind-driven case, while downwelling results in destratified nutrient-poor waters. The combination of these sporadic wind- and current-driven processes may drive an important part of the high-frequency variability of coastal temperature and nutrient content. Our results suggest that localized nutrient enrichment events of variable magnitude are favored at specific latitudes and seasons, potentially impacting coastal ecosystems.

  11. The variability time-scales and brightness temperatures of radio flares from stars to supermassive black holes

    NASA Astrophysics Data System (ADS)

    Pietka, M.; Fender, R. P.; Keane, E. F.

    2015-02-01

    In this paper we compile the analysis of ˜200 synchrotron flare events from ˜90 distinct objects/events for which the distance is well established, and hence the peak luminosity can be accurately estimated. For each event we measure this peak and compare it to the rise and decay time-scales, as fit by exponential functions, which allows us in turn to estimate a minimum brightness temperature for all the events. The astrophysical objects from which the flares originate vary from flare stars to supermassive black holes in active galactic nuclei, and include both repeating phenomena and single cataclysmic events (such as supernovae and gamma-ray burst afterglows). The measured time-scales vary from minutes to longer than years, and the peak radio luminosities range over 22 orders of magnitude. Despite very different underlying phenomena, including relativistic and non-relativistic regimes, and highly collimated versus isotropic phenomena, we find a broad correlation between peak radio luminosity and rise/decay time-scales, approximately of the form L ? ?5. This rather unexpectedly demonstrates that the estimated minimum brightness temperature, when based upon variability time-scales, and with no attempt to correct for relativistic boosting, is a strongly rising function of source luminosity. It furthermore demonstrates that variability time-scales could be used as an early diagnostic of source class in future radio transient surveys. As an illustration of radio transients parameter space, we compare the synchrotron events with coherent bursts at higher brightness temperatures to illustrate which regions of radio transient parameter space have been explored.

  12. Highly variable functional response of microbial communities to experimental temperature disturbances

    NASA Astrophysics Data System (ADS)

    Wanek, Wolfgang; Mooshammer, Maria; Hofhansl, Florian; Frank, Alexander H.; Leitner, Sonja; Schnecker, Jörg; Wild, Birgit; Watzka, Margarete; Keiblinger, Katharina M.; Zechmeister-Boltenstern, Sophie; Richter, Andreas

    2015-04-01

    Climate change is expected to alter the frequency and intensity of climate excursions, such as heat, drought and freeze-thaw events, requiring a thorough mechanistic understanding of the response of microbially-mediated nutrient cycling processes to such transient but severe disturbances. Here, we investigated the resistance and resilience of major gross processes of microbial carbon (C), nitrogen (N) and phosphorus (P) cycling, determined by isotope pool dilution assays, as well as potential enzyme activities in decomposing beech litter to two contrasting temperature disturbances (freeze-thaw and heat treatment for 9 days) in four different litter types. Microbial processes were substantially altered by the temperature disturbances but both the magnitude and direction of the disturbance effect varied among them. Phosphorus processes and hydrolytic enzyme activities showed lowest resistance as well as resilience, whereas N processes were more resistant and C processes intermediate. In general, responses of microbial processes were mainly consistent across disturbances but partially dependent on litter-specific microbial communities. The transient disturbances affected the relative availability of essential nutrients through a decoupling of microbial C, N and P cycling processes. Understanding the underlying mechanisms through which a decoupling of the supply of these elements as a result of microbial responses to environmental disturbances occurs will help to better predicting ecosystem responses to global change.

  13. Temperature variability analysis using wavelets and multiscale entropy in patients with systemic inflammatory response syndrome, sepsis, and septic shock

    PubMed Central

    2012-01-01

    Background Even though temperature is a continuous quantitative variable, its measurement has been considered a snapshot of a process, indicating whether a patient is febrile or afebrile. Recently, other diagnostic techniques have been proposed for the association between different properties of the temperature curve with severity of illness in the Intensive Care Unit (ICU), based on complexity analysis of continuously monitored body temperature. In this study, we tried to assess temperature complexity in patients with systemic inflammation during a suspected ICU-acquired infection, by using wavelets transformation and multiscale entropy of temperature signals, in a cohort of mixed critically ill patients. Methods Twenty-two patients were enrolled in the study. In five, systemic inflammatory response syndrome (SIRS, group 1) developed, 10 had sepsis (group 2), and seven had septic shock (group 3). All temperature curves were studied during the first 24 hours of an inflammatory state. A wavelet transformation was applied, decomposing the signal in different frequency components (scales) that have been found to reflect neurogenic and metabolic inputs on temperature oscillations. Wavelet energy and entropy per different scales associated with complexity in specific frequency bands and multiscale entropy of the whole signal were calculated. Moreover, a clustering technique and a linear discriminant analysis (LDA) were applied for permitting pattern recognition in data sets and assessing diagnostic accuracy of different wavelet features among the three classes of patients. Results Statistically significant differences were found in wavelet entropy between patients with SIRS and groups 2 and 3, and in specific ultradian bands between SIRS and group 3, with decreased entropy in sepsis. Cluster analysis using wavelet features in specific bands revealed concrete clusters closely related with the groups in focus. LDA after wrapper-based feature selection was able to classify with an accuracy of more than 80% SIRS from the two sepsis groups, based on multiparametric patterns of entropy values in the very low frequencies and indicating reduced metabolic inputs on local thermoregulation, probably associated with extensive vasodilatation. Conclusions We suggest that complexity analysis of temperature signals can assess inherent thermoregulatory dynamics during systemic inflammation and has increased discriminating value in patients with infectious versus noninfectious conditions, probably associated with severity of illness. PMID:22424316

  14. Influence of weather conditions on milk production and rectal temperature of Holsteins fed two levels of concentrate

    NASA Astrophysics Data System (ADS)

    Kabuga, J. D.; Sarpong, K.

    1991-12-01

    Twelve lactating Holstein cows in 2nd lactation were allocated randomly, six each, to two feeding treatments: high concentrate (1 kg dairy concentrate to 2 kg milk produced) and low concentrate (1 kg dairy concentrate to 4 kg milk produced) from 7 to 106 days postcalving. Forage and water were provided adalibitum. Milk and butter fat yields and rectal temperatures were examined in relation to 9 weather variables (minimum, maximum and mean temperatures, relative humidity, temperature-humidity index (THI), radiation, wind velocity and mean temperature of the previous day). Averages for milk yield, fat yield and rectal temperature were respectively 20.4 kg, 0.7 kg and 38.9°C for the high concentrate treatment and 18.4 kg, 0.6 kg and 38.6°C for the low concentrate treatment. Weather conditions accounted for 5.6%, 0.8% and 10.8% of the day to day variation in milk yield, fat yield and rectal remperature, respectively, for the high concentrate group and 29.4%, 9.7% and 0.6%, respectively, for the low concentrate group. Only measures of ambient temperature, especially mean temperature, were closely associated with these traits.

  15. Lagged temperature effect with mosquito transmission potential explains dengue variability in southern Taiwan: insights from a statistical analysis.

    PubMed

    Chen, Szu-Chieh; Liao, Chung-Min; Chio, Chia-Pin; Chou, Hsiao-Han; You, Shu-Han; Cheng, Yi-Hsien

    2010-09-01

    The purpose of this study was to link meteorological factors and mosquito (Aedes aegypti) abundance to examine the potential effects of climate variations on patterns of dengue epidemiology in Taiwan during 2001-2008. Spearman's rank correlation tests with and without time-lag were performed to investigate the overall correlation between dengue incidence rates and meteorological variables (i.e., minimum, mean, and maximum temperatures, relative humidity (RH), and rainfall) and percentage Breteau index (BI) level >2 in Taipei and Kaohsiung of northern and southern Taiwan, respectively. A Poisson regression analysis was performed by using a generalized estimating equations (GEE) approach. The most parsimonious model was selected based on the quasi-likelihood based information criterion (QICu). Spearman's rank correlation tests revealed marginally positive trends in the weekly mean (rho=0.28, p<0.0001), maximum (rho=0.26, p<0.0001), and minimum (rho=0.30, p<0.0001) temperatures in Taipei. However, in Kaohsiung, all negative trends were found in the weekly mean (rho=-0.32, p<0.0001), maximum (rho=-0.30, p<0.0001), and minimum (rho=-0.32, p<0.0001) temperatures. This study concluded that based on the GEE approach, rainfall, minimum temperature, and RH, all with 3-month lag, and 1-month lag of percentage BI level >2 are the significant predictors of dengue incidence in Kaohsiung (QICu=-277.77). This study suggested that warmer temperature with 3-month lag, elevated humidity with high mosquito density increased the transmission rate of human dengue fever infection in southern Taiwan. PMID:20542536

  16. STABILITY CONSTANTS OF NP(V) COMPLEXES WITH FLOURIDE AND SULFATE AT VARIABLE TEMPERATURES

    SciTech Connect

    Y. Xia; J.I. Friese; D.A. Moore; L. Rao

    2005-07-11

    A solvent extraction method was used to determine the stability constants of Np(V) complexes with fluoride and sulfate in 1.0 M NaClO{sub 4} from 25 C to 60 C. The distribution ratio of Np(V) between the organic and aqueous phases was found to decrease as the concentrations of fluoride and sulfate were increased. Stability constants of the 1:1 Np(V)-fluoride complexes and the 1:1 Np(V)-sulfate and 1:2 Np(V)-sulfate complexes, dominant in the aqueous phase under the experimental conditions, were calculated from the effect of [F{sup -}] and [SO{sub 4}{sup 2-}] on the distribution ratio. The enthalpy and entropy of complexation were calculated from the stability constants at different temperatures by using the Van't Hoff equation.

  17. Caspian Sea surface circulation variability inferred from satellite altimeter and sea surface temperature

    NASA Astrophysics Data System (ADS)

    Gunduz, Murat

    2014-02-01

    Multiyear (1993-2007) satellite-derived Sea Level Anomaly (SLA), Sea Surface Temperature (SST), and model-derived mean dynamic topography were used together to analyze climatological and interannual variations of the Caspian Sea surface circulation. Constructed geostrophic currents are in good agreement with the known circulation features of the Caspian Sea, obtained from models and verified by some drifter observations. It is shown that the climatological surface circulation of the Middle Caspian Sea (MCS) is dominated by a basin-wide cyclonic circulation in winter, switching to an anticyclonic circulation in summer. A dipole pattern (an anticyclonic eddy near 39.5°N and a cyclonic one near 38°N) exist in the Southern Caspian Sea (SCS) (stronger from September to January). Evaluation of the multiyear geostrophic velocities shows that the Caspian Sea surface circulation exhibits strong interannual variations, with the location and intensity of the circulation patterns changing from one year to another.

  18. Variable content and distribution of arabinogalactan proteins in banana (Musa spp.) under low temperature stress

    PubMed Central

    Yan, Yonglian; Taká?, Tomáš; Li, Xiaoquan; Chen, Houbin; Wang, Yingying; Xu, Enfeng; Xie, Ling; Su, Zhaohua; Šamaj, Jozef; Xu, Chunxiang

    2015-01-01

    Information on the spatial distribution of arabinogalactan proteins (AGPs) in plant organs and tissues during plant reactions to low temperature (LT) is limited. In this study, the extracellular distribution of AGPs in banana leaves and roots, and their changes under LT stress were investigated in two genotypes differing in chilling tolerance, by immuno-techniques using 17 monoclonal antibodies against different AGP epitopes. Changes in total classical AGPs in banana leaves were also tested. The results showed that AGP epitopes recognized by JIM4, JIM14, JIM16, and CCRC-M32 antibodies were primarily distributed in leaf veins, while those recognized by JIM8, JIM13, JIM15, and PN16.4B4 antibodies exhibited predominant sclerenchymal localization. Epitopes recognized by LM2, LM14, and MAC207 antibodies were distributed in both epidermal and mesophyll cells. Both genotypes accumulated classical AGPs in leaves under LT treatment, and the chilling tolerant genotype contained higher classical AGPs at each temperature treatment. The abundance of JIM4 and JIM16 epitopes in the chilling-sensitive genotype decreased slightly after LT treatment, and this trend was opposite for the tolerant one. LT induced accumulation of LM2- and LM14-immunoreactive AGPs in the tolerant genotype compared to the sensitive one, especially in phloem and mesophyll cells. These epitopes thus might play important roles in banana LT tolerance. Different AGP components also showed differential distribution patterns in banana roots. In general, banana roots started to accumulate AGPs under LT treatment earlier than leaves. The levels of AGPs recognized by MAC207 and JIM13 antibodies in the control roots of the tolerant genotype were higher than in the chilling sensitive one. Furthermore, the chilling tolerant genotype showed high immuno-reactivity against JIM13 antibody. These results indicate that several AGPs are likely involved in banana tolerance to chilling injury. PMID:26074928

  19. Interannual Variability in PMCs from AIM/CIPS

    NASA Astrophysics Data System (ADS)

    Randall, C. E.; Harvey, V. L.; Holt, L. A.; Lumpe, J. D., Jr.; Bailey, S. M.; Russell, J. M., III

    2014-12-01

    The NASA Aeronomy of Ice in the Mesosphere (AIM) mission has measured polar mesospheric cloud (PMC) parameters since May of 2007, including eight PMC seasons in the northern hemisphere (NH) and seven in the southern hemisphere (SH). In this presentation we describe interannual variations in the clouds as measured by the AIM Cloud Imaging and Particle Size (CIPS) instrument, and relate these to measurements of temperature and water vapor from the NASA Microwave Limb Sounder (MLS) and Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instruments. Overall, interannual variability is larger in the SH than in the NH. In both hemispheres, there is significant variability from season to season in the season onset, with somewhat less variability in the season end. There is about a 20-day spread in the season onset dates in the NH; the NH 2013 season was the earliest, and began a week earlier than any other NH season. In mid-season the NH PMC frequencies were generally highest in 2011, 2013 and 2014, and lowest in 2007 and 2009, but with substantial day-to-day variations that increase with decreasing latitude. In the SH, the earliest season onsets occurred in 2009-2010, 2012-2013, and 2013-2014, which started about a month earlier than 2010-2011 and 2011-2012. The SH 2009-2010 season continued to show more PMCs than any other season throughout the summer, whereas PMC frequencies in the 2012-2013 and 2013-2014 seasons dropped to average values in mid-January. These results will be discussed in terms of teleconnections and solar cycle effects.

  20. Processes of interannual mixed layer temperature variability in the thermocline ridge of the Indian Ocean

    NASA Astrophysics Data System (ADS)

    Praveen Kumar, B.; Vialard, J.; Lengaigne, M.; Murty, V. S. N.; Foltz, G. R.; McPhaden, M. J.; Pous, S.; de Boyer Montégut, C.

    2014-11-01

    Sea-surface temperature interannual anomalies (SSTAs) in the thermocline ridge of the southwestern tropical Indian Ocean (TRIO) have several well-documented climate impacts. In this paper, we explore the physical processes responsible for SSTA evolution in the TRIO region using a combination of observational estimates and model-derived surface layer heat budget analyses. Vertical oceanic processes contribute most to SSTA variance from December to June, while lateral advection dominates from July to November. Atmospheric fluxes generally damp SSTA generation in the TRIO region. As a result of the phase opposition between the seasonal cycle of vertical processes and lateral advection, there is no obvious peak in SSTA amplitude in boreal winter, as previously noted for heat content anomalies. Positive Indian Ocean Dipole (IOD) events and the remote influence of El Niño induce comparable warming over the TRIO region, though IOD signals peak earlier (November-December) than those associated with El Niño (around March-May). Mechanisms controlling the SSTA growth in the TRIO region induced by these two climate modes differ strongly. While SSTA growth for the IOD mostly results from southward advection of warmer water, increased surface shortwave flux dominates the El Niño SSTA growth. In both cases, vertical oceanic processes do not contribute strongly to the initial SSTA growth, but rather maintain the SSTA by opposing the effect of atmospheric negative feedbacks during the decaying phase.

  1. Effect of acute pH depression on the survival of the freshwater amphipod Hyalella azteca at variable temperatures: field and laboratory studies

    Microsoft Academic Search

    Wilfred Pilgrim; Michael D. B. Burt

    1993-01-01

    Field observations on temperature and pH of a small pond showed that a amphipod population of Hyalella azteca was exposed to variable seasonal pH between 5.10–5.85, and water temperatures between 2–21 °C. Laboratory experiments were designed to simulate seasonal temperatures and field pHs of a small pond habitat. Laboratory bioassay experiments were conducted to determine the survival of Hyalella azteca

  2. Economic and technical assessment of the desiccant wheel effect on the thermal performance of cross flow cooling towers in variable wet bulb temperature

    NASA Astrophysics Data System (ADS)

    Banooni, Salem; Chitsazan, Ali

    2014-05-01

    Performance improvements of cross flow cooling towers in variable wet bulb temperature were performed. A conventional mathematical model is used to predict desiccant wheel effect on the performance of cooling tower. It is found that by using optimum parameters of desiccant wheel, the inlet air wet bulb temperature into the cooling tower would decrease more than 6 °C and outlet water temperature would decrease more than 4 °C.

  3. The Atlantic Multidecadal Variability in surface and deep ocean temperature and salinity fields from unperturbed climate simulations

    NASA Astrophysics Data System (ADS)

    Zanchettin, D.; Jungclaus, J. H.

    2013-12-01

    Large multidecadal fluctuations in basin-average sea-surface temperature (SST) are a known feature of observed, reconstructed and simulated variability in the North Atlantic Ocean. This phenomenon is often referred to as Multidecadal Atlantic Variability or AMV. Historical AMV fluctuations are associated with analog basin-scale changes in sea-surface salinity, so that warming corresponds to salinification and cooling to freshening [Polyakov et al., 2005]. The surface imprint of the AMV further corresponds to same-sign fluctuations in the shallow ocean and with opposite-sign fluctuations in the deep ocean for both temperature and salinity [Polyakov et al., 2005]. This out-of-phase behavior reflects the thermohaline overturning circulation shaping North Atlantic's low-frequency variability. Several processes contribute to the AMV, involving both ocean-atmosphere coupled processes and deep ocean circulation [e.g., Grossmann and Klotzbach, 2009]. In particular, recirculation in the North Atlantic subpolar gyre region of salinity anomalies from Arctic freshwater export may trigger multidecadal variability in the Atlantic meridional overturning circulation, and therefore may be part of the AMV [Jungclaus et al., 2005; Dima and Lohmann, 2007]. With this contribution, we aim to improve the physical interpretation of the AMV by investigating spatial and temporal patterns of temperature and salinity fields in the shallow and deep ocean. We focus on two unperturbed millennial-scale simulations performed with the Max Planck Institute Earth system model in its paleo (MPI-ESM-P) and low-resolution (MPI-ESM-LR) configurations, which provide reference control climates for assessments of pre-industrial and historical climate simulations. The two model configurations only differ for the presence, in MPI-ESM-LR, of an active module for dynamical vegetation. We use spatial-average indices and empirical orthogonal functions/principal components to track the horizontal and vertical propagation of temperature and salinity anomalies related to the AMV. In particular, we discuss the potential predictability of multidecadal fluctuations in North Atlantic SSTs based on indices derived from the sea-surface salinity field. We show how the two simulations provide AMV realizations with some distinguishable characteristics, e.g., the typical fluctuations' frequencies and the linkage with the North Atlantic meridional overturning and gyre circulations. We further show how information gained by investigating different definitions of the AMV [Zanchettin et al., 2013] helps designing numerical sensitivity studies for understanding the mechanism(s) behind this phenomenon, concerning both its origin and global impacts. References Dima, M., and G. Lohmann [2007], J. Clim., 20, 2706-2719, doi:10.1175/JCLI4174.1 Jungclaus, J.H., et al. [2005], J. Clim., 18, 4013- 4031, doi:10.1175/JCLI3462.1 Polyakov, I. V., et al. [2005], J. Clim., 18:4562-4581 Grossmann, I., and P. J. Klotzbach [2009], J. Geophys. Res., 114, D24107, doi:10.1029/2009JD012728 Zanchettin D., et al. [2013], Clim. Dyn., doi:10.1007/s00382-013-1669-0

  4. Sea surface temperature variability of the Peru-Chile Current during the previous ten interglacials

    NASA Astrophysics Data System (ADS)

    Caniupan, M.; Martinez-Mendez, G.; Lamy, F.; Hebbeln, D.; Mohtadi, M.; Pantoja, S.

    2014-12-01

    There are several interglacial periods during the Quaternary that were characterized by climates warmer than present and higher sea level and thus may serve as analogues for future global warming scenarios. These include Marine Isotope Stages (MIS) 5e, 9c and 11c. Little is known about past sea surface temperatures (SST) during these warm intervals in the Southern Hemisphere, particularly along the Peru-Chile Current (PCC) which plays a critical role in the Southern Hemisphere surface circulation as it connects the low and high latitudes by transporting sub-polar water masses and thus, a high-latitude climate signal towards the tropics. Here, we present new high-resolution alkenone-derived SST records from marine sediment cores located beneath the PCC. Core GeoB15016 was recovered from off northern Chile (27.5°S; 71.1°W) with the seafloor drill rig MARUM-MeBo. We analyzed the ca. 60 meters composite depth complemented by gravity core GeoB3375-1 (27.5°S; 71.3°W) for the upper part to generate a continuous record that extends back to 970 ka BP. Our record is the first continuous SST reconstruction from the Chilean margin extending back to MIS 25. SST varies between ~8°C and ~20°C over the past ~970 ka. Glacial-interglacial SST amplitudes are in the order of 6°C (see Groeneveld's et al. contribution for Mg/Ca-derived Glacial SST estimations). During MIS 5e, 7e, 9c and 11c, the record reaches SST maxima which are ca. 3ºC warmer than present annual mean SST in the area. Our results suggest a substantial warming of the PCC over past interglacials that may reflect reduced advection of subantarctic surface water from the south and/or enhanced tropical influence from the north.

  5. Biodegradation of Variable-Chain-Length Alkanes at Low Temperatures by a Psychrotrophic Rhodococcus sp.

    PubMed Central

    Whyte, Lyle G.; Hawari, Jalal; Zhou, Edward; Bourbonnière, Luc; Inniss, William E.; Greer, Charles W.

    1998-01-01

    The psychrotroph Rhodococcus sp. strain Q15 was examined for its ability to degrade individual n-alkanes and diesel fuel at low temperatures, and its alkane catabolic pathway was investigated by biochemical and genetic techniques. At 0 and 5°C, Q15 mineralized the short-chain alkanes dodecane and hexadecane to a greater extent than that observed for the long-chain alkanes octacosane and dotriacontane. Q15 utilized a broad range of aliphatics (C10 to C21 alkanes, branched alkanes, and a substituted cyclohexane) present in diesel fuel at 5°C. Mineralization of hexadecane at 5°C was significantly greater in both hydrocarbon-contaminated and pristine soil microcosms seeded with Q15 cells than in uninoculated control soil microcosms. The detection of hexadecane and dodecane metabolic intermediates (1-hexadecanol and 2-hexadecanol and 1-dodecanol and 2-dodecanone, respectively) by solid-phase microextraction–gas chromatography-mass spectrometry and the utilization of potential metabolic intermediates indicated that Q15 oxidizes alkanes by both the terminal oxidation pathway and the subterminal oxidation pathway. Genetic characterization by PCR and nucleotide sequence analysis indicated that Q15 possesses an aliphatic aldehyde dehydrogenase gene highly homologous to the Rhodococcus erythropolis thcA gene. Rhodococcus sp. strain Q15 possessed two large plasmids of approximately 90 and 115 kb (shown to mediate Cd resistance) which were not required for alkane mineralization, although the 90-kb plasmid enhanced mineralization of some alkanes and growth on diesel oil at both 5 and 25°C. PMID:9647833

  6. Temperature drives inter-annual variability of growing season CO2 and CH4 fluxes of Siberian lowland tundra

    NASA Astrophysics Data System (ADS)

    Kutzbach, Lars; Wille, Christian; Runkle, Benjamin; Schreiber, Peter; Sachs, Torsten; Langer, Moritz; Boike, Julia; Pfeiffer, Eva-Maria

    2015-04-01

    Due to the logistic and technical difficulties associated with experimental work in high latitudes, long-term measurements of CO2 and CH4 fluxes from arctic ecosystems are still rare, and published trace gas balances often rely on measurements from one or few growing seasons. The inter-annual variability of environmental conditions such as temperature, precipitation, snow cover, and timing of snow melt can be high in the Arctic, especially for regions which are influenced by both continental and maritime climates, such as the Siberian arctic lowlands. For these ecosystems, we must also expect a great inter-annual variability in the balance of trace gases. Multi-annual data sets are needed to investigate this variability and its drivers. Here we present multi-annual late summer CO2 and CH4 flux data from the Lena River Delta in the Siberian Arctic (72° N, 126° E). The study site Samoylov Island is characterized by polygonal lowland tundra, a vegetation dominated by mosses and sedges, a soil complex of Glacic, Turbic and Histic Cryosols, and an active layer depth of on average 0.5 m. Seasonal flux measurements were carried out with the eddy covariance technique during the 13-year period 2002 - 2014. Within this period, CO2 flux data overlaps during 37 days (20 July - 25 August) for 12 years, and CH4 flux data overlaps during 25 days (28 July - 21 August) for 9 years. Cumulative net ecosystem CO2 exchange (NEE) during the late summer overlap period is fairly consistent for 9 out of 12 years with a CO2 uptake of 1.9 ± 0.1 mol m-2. Three years show a clearly smaller uptake of

  7. Large-scale variability of atmospheric deep convection in relation to sea surface temperature in the tropics

    SciTech Connect

    Zhang, C. (Univ. of Washington, Seattle, WA (United States))

    1993-10-01

    Empirical relationships between tropical sea surface temperature (SST) and atmospheric deep convection are examined. The relationships are addressed from two aspects: how deep convection varies with changing SST and how it varies at constant SST. Deep convection remains weak and rarely observed for SST < 26[degrees]C; the frequency and mean intensity of deep convection substantially increase with SST from 26[degrees]C up to about 29.5[degrees]-30[degrees]C, and then decay for further increasing SST. Meanwhile, in the warm pool region with SST > 27[degrees]C, situations of no deep convection and vigorous deep convection can both be observed; the areal coverage of convectively related high clouds is always dominated by that of clear sky and low clouds. The variability of deep convection, thus becomes larger for higher SST. The large variability of deep convection at constant high SST is attributable to the differences in mean spatial distributions and in the annual variations of SST and deep convection. In general, the relationship is less apparent for the intertropical convergence zone than the other regions of the tropical oceans. The empirical relationship varies in space and time. In the warm pool region, the absence of deep convection at particular locations and times and the large variability of deep convection do not imply changes in high SST have little effect on deep convection. Rather, they reflect other factors can sometimes be dominantly unfavorable to deep convection. As SST increases, deep convection becomes more frequent and tends to be more intense on average, regardless of other factors. This increase in deep convection with SST is smooth and continuous. 52 refs., 26 figs., 1 tab.

  8. Numerical modelling of POC yearly dynamics in the southern Baltic under variable scenarios of nutrients, light and temperature

    NASA Astrophysics Data System (ADS)

    Dzierzbicka-Glowacka, L.; Kuli?ski, K.; Maciejewska, A.; Jakacki, J.; Pempkowiak, J.

    2011-03-01

    This paper presents various scenarios of the particulate organic carbon (POC) in the southern Baltic Sea. The study is based on a one-dimensional Particulate Organic Carbon model (1-D POC). Mathematically, the pelagic variables of 1-D POC model are described by a second-order partial differential equations of the diffusion type with biogeochemical sources and sinks. The POC concentration is determined as the sum of phytoplankton, zooplankton and dead organic matter (detritus) concentrations. The temporal changes in the phytoplankton biomass are caused by primary production, mortality, grazing by zooplankton and sinking. The zooplankton biomass is affected by ingestion, excretion, faecal production, mortality, and carnivorous grazing. The changes in the pelagic detritus concentration are determined by input of: dead phytoplankton and zooplankton, natural mortality of predators, faecal pellets, and sinks: sedimentation, zooplankton grazing and biochemical decomposition. The 1-D POC model was used to simulate temporal dynamics of POC in the southern Baltic Sea (Gdansk Deep, Bornholm Deep and Gotland Deep) under scenarios characterized by different temperature, nutrients and light. Daily, monthly, seasonal and annual variabilities of POC in the upper water layer are presented for the different scenarios. The starting-point of the numerical simulations was assumed as average values of the investigated pelagic variables for 1965-1998 period. Two- to three-fold increases of POC concentrations in late spring were revealed as well as the shift towards postponed maximum POC concentration. It is speculated that, due to POC increase, oxygenation of under-halocline water layer will decrease, while supply of food to organisms from higher trophic level should increase.

  9. Madagascar corals track sea surface temperature variability in the Agulhas Current core region over the past 334 years.

    PubMed

    Zinke, J; Loveday, B R; Reason, C J C; Dullo, W-C; Kroon, D

    2014-01-01

    The Agulhas Current (AC) is the strongest western boundary current in the Southern Hemisphere and is key for weather and climate patterns, both regionally and globally. Its heat transfer into both the midlatitude South Indian Ocean and South Atlantic is of global significance. A new composite coral record (Ifaty and Tulear massive Porites corals), is linked to historical AC sea surface temperature (SST) instrumental data, showing robust correlations. The composite coral SST data start in 1660 and comprise 200 years more than the AC instrumental record. Numerical modelling exhibits that this new coral derived SST record is representative for the wider core region of the AC. AC SSTs variabilities show distinct cooling through the Little Ice Age and warming during the late 18(th), 19th and 20th century, with significant decadal variability superimposed. Furthermore, the AC SSTs are teleconnected with the broad southern Indian and Atlantic Oceans, showing that the AC system is pivotal for inter-ocean heat exchange south of Africa. PMID:24637665

  10. Low-frequency variability and zonal contrast in Sahel rainfall and Atlantic sea surface temperature teleconnections during the last century

    NASA Astrophysics Data System (ADS)

    Dieppois, B.; Durand, A.; Fournier, M.; Diedhiou, A.; Fontaine, B.; Massei, N.; Nouaceur, Z.; Sebag, D.

    2014-07-01

    This study systematically examines teleconnections between Atlantic sea surface temperature (SST) and the west-east distribution of Sahel rainfall throughout the twentieth century, taking nonstationarity into account. Sahel rainfall variability of six selected rain gauges displays three dominant time scales: multi-decadal (>20 years), quasi-decadal (8-18 years) and interannual (2-8 years). Regarding their patterns of low-frequency scales, three coherent Sahelian subregions can be identified: the Atlantic Coast (Dakar), western-central Sahel (Nioro and Mopti) and eastern Sahel (Niamey, Maradi, Maine-Soroa). Cross-analyses combining spectral and multivariate analyses of 20 station-based data and West-African gridded rainfall data statistically confirm dissimilarities between the western and eastern Sahel. Western and eastern Sahel rainfall data are correlated with SSTs from different regions of the Atlantic Ocean, especially in the North and tropical South Atlantic. As determined by wavelet coherence and phase, in-phase relationship with North Atlantic SSTs only occurs in wet periods and at the multi- and quasi-decadal scales. This teleconnection depends on the time period and the time scale, displaying a NW-SE pattern, which suggests nonuniform modulations of meridional displacements of the Intertropical Convergence Zone (ITCZ). Tropical South Atlantic SST variability is often related to opposite patterns between the Gulf of Guinean Coast (in phase) and Sahel region (out of phase).

  11. Madagascar corals track sea surface temperature variability in the Agulhas Current core region over the past 334 years

    PubMed Central

    Zinke, J.; Loveday, B. R.; Reason, C. J. C.; Dullo, W.-C.; Kroon, D.

    2014-01-01

    The Agulhas Current (AC) is the strongest western boundary current in the Southern Hemisphere and is key for weather and climate patterns, both regionally and globally. Its heat transfer into both the midlatitude South Indian Ocean and South Atlantic is of global significance. A new composite coral record (Ifaty and Tulear massive Porites corals), is linked to historical AC sea surface temperature (SST) instrumental data, showing robust correlations. The composite coral SST data start in 1660 and comprise 200 years more than the AC instrumental record. Numerical modelling exhibits that this new coral derived SST record is representative for the wider core region of the AC. AC SSTs variabilities show distinct cooling through the Little Ice Age and warming during the late 18th, 19th and 20th century, with significant decadal variability superimposed. Furthermore, the AC SSTs are teleconnected with the broad southern Indian and Atlantic Oceans, showing that the AC system is pivotal for inter-ocean heat exchange south of Africa. PMID:24637665

  12. Growing season temperature and precipitation variability and extremes in the U.S. Corn Belt from 1981 to 2012

    NASA Astrophysics Data System (ADS)

    Dai, S.; Shulski, M.

    2013-12-01

    Climate warming and changes in rainfall patterns and increases in extreme events are resulting in higher risks of crop failures. A greater sense of urgency has been induced to understand the impacts of past climate on crop production in the U.S. As one of the most predominant sources of feed grains, corn is also the main source of U.S. ethanol. In the U.S. Corn Belt, region-scale evaluation on temperature and precipitation variability and extremes during the growing season is not well-documented yet. This study is part of the USDA-funded project 'Useful to Usable: Transforming climate variability and change information for cereal crop producers'. The overall goal of our work is to study the characteristics of average growing season conditions and changes in growing season temperature- and precipitation-based indices that are closely correlated with corn grain yield in the U.S. Corn Belt. The research area is the twelve major Corn Belt states, including IL, IN, IA, KS, MI, MN, MO, NE, OH, SD, ND, and WI. Climate data during 1981-2010 from 132 meteorological stations (elevation ranges from 122 m to 1,202 m) are used in this study, including daily minimum, maximum, and mean temperature, and daily precipitation. From 1981 to 2012, beginning date (BD), ending date (ED), and growing season length (GSL) in the climatological corn growing season are studied. Especially, during the agronomic corn growing season, from Apr to Oct, temperature- and precipitation-based indices are analyzed. The temperature-based indices include: number of days with daily mean temperature below 10°C, number of days with daily mean temperature above 30°C, the sum of growing degree days (GDD) between 10°C to 30°C (GDD10,30, growth range for corn), the sum of growing degree days above 30°C (GDD30+, exposure to harmful warming for corn), the sum of growing degree days between 0°C and 44°C (GDD0,44, survival range limits for corn), the sum of growing degree days between 5°C and 35°C (GDD5,35, growth range limits for corn), and the sum of growing degree days between 20°C and 22°C (GDD20,22, optimal growth range for corn). And the precipitation-based indices include: cumulative precipitation, consecutive dry days, and number of extreme precipitation events in June. As to the decadal trend analysis in climatic factors, Sen's Nonparametric Estimator of Slope and the nonparametric Mann-Kendall test are used. In the U.S. Corn Belt, annual mean Tavg ranges from 5.7°C to 14.7°C, and annual cumulative precipitation ranges from 396 mm to 1,203 mm. According to the decadal trend of annual mean Tavg and annual cumulative precipitation, 30 stations (45%) demonstrate a warm and dry trend, and 28 stations demonstrate a warm and wet trend. In monthly scale, Jun mean Tmin presents the most significantly increasing trend, and no significant decreasing or zero trend is detected from 1981 to 2012. During the climatological corn growing season, BD ranges from 76 to 128 DOY, ED ranges from 276 to 316 DOY, and GSL ranges from 150 to 242 days. From 1981 to 2012, BD is significantly advanced at the rate of 1 to 8 DOY per decade, ED is significantly delayed at the rate of 1 to 5 per decade, and GSL is significantly prolonged at the rate of 1 to 11 days per decade.

  13. Temperature variability at Dürres Maar, Germany during the Migration Period and at High Medieval Times, inferred from stable carbon isotopes of Sphagnum cellulose

    NASA Astrophysics Data System (ADS)

    Moschen, R.; Kühl, N.; Peters, S.; Vos, H.; Lücke, A.

    2011-09-01

    This paper presents a high resolution reconstruction of local growing season temperature (GST) anomalies at Dürres Maar, Germany, spanning the last two millennia. The GST anomalies were derived from a stable carbon isotope time series of cellulose chemically extracted from Sphagnum leaves (?13Ccellulose) separated from a kettle-hole peat deposit of several metres thickness. The temperature reconstruction is based on the Sphagnum ?13Ccellulose/temperature dependency observed in calibration studies. Reconstructed GST anomalies show considerable centennial and decadal scale variability. A cold and presumably wet phase with below-average temperature is reconstructed between the 4th and 7th century AD which is in accordance with the so called European Migration Period, marking the transition from the Late Roman Period to the Early Middle Ages. At High Medieval Times, the amplitude in the reconstructed temperature variability is most likely overestimated; nevertheless, above-average temperatures are obvious during this time span, which are followed by a temperature decrease. On the contrary, a pronounced Late Roman Climate Optimum, often described as similarly warm or even warmer as medieval times, could not be detected. The temperature signal of the Little Ice Age (LIA) is not preserved in Dürres Maar due to considerable peat cutting that takes place in the first half of the 19th century. The local GST anomalies show a remarkable agreement to northern hemispheric temperature reconstructions based on tree-ring datasets and are also in accordance with climate reconstructions on the basis of lake sediments, glacier advances and retreats, and historical datasets. Most notably, e.g., during the Early Middle Ages and at High Medieval Times, temperatures were neither low nor high in general. Rather high frequency temperature variability with multiple narrow intervals of below- and above-average temperatures at maximum lasting a few decades are reconstructed. Especially the agreements between our estimated GST anomalies and temperature reconstructions derived from tree-ring chronologies indicate the great potential of Sphagnum ?13Ccellulose time series from peat deposits for palaeoclimate research. This is particularly the case, given that a quantitative ?13Ccellulose/temperature relationship has been found for several Sphagnum species. Although the time resolution of Sphagnum ?13Ccellulose datasets certainly wouldn't reach the annual resolution of tree-ring data, reconstructions of past temperature variability on the basis of this proxy hold one particular advantage: often due to relatively high peat accumulation rates, especially in kettle-hole bogs accumulated on temperate latitudes over periods of up to several millennia, they allow extending temperature reconstructions based on tree-ring series into the past to enhance our knowledge of natural climate variability during the Holocene.

  14. Estimates of Surface and Subsurface Forcing for Decadal Sea Surface Temperature Variability in the Mid-Latitude North Pacific

    NASA Astrophysics Data System (ADS)

    Tomita, T.; Xie, S.; Nonaka, M.

    2002-12-01

    The upper ocean, atmosphere and their interaction over the North Pacific exhibit pronounced decadal to interdecadal variations. A diagnostic equation for analyzing the heat budget for decadal variability in winter sea surface temperature (SST) is derived that can properly account for subsurface geostrophic advection, and strong seasonal cycle in the depth and temperature of the ocean mixed layer. A model-assimilated ocean dataset, partially validated for the period of the TOPEX/Poseidon mission, is used to evaluate the relative importance of subsurface advection and surface forcing due to wind-induced turbulent heat flux and Ekman advection. For our analysis, two key regions are chosen where decadal SST variance reaches local maxima, centered at 180_?E, 42_?N (Region A) and 155_?W, 35_?N (Region B), respectively. Region B is under the direct influence of the Aleutian Low, where the surface effects are dominant. Region A is part of the Kuroshio-Oyashio Extension, where the winter mixed layer is deep and the subsurface geostrophic advection contributes significantly to low-frequency winter SST variations. Our analysis suggests that anomalous geostrophic advection changes signs north and south 38_?N, presumably as a result of ocean gyre circulation adjustment to wind changes to the east. The surface forcing shows a larger-scale structure covering the entire mid-latitude North Pacific, in response to basin-wide changes in atmospheric circulation.

  15. Variability and Predictability of West African Droughts. A review in the role of Sea Surface Temperature Anomalies

    NASA Astrophysics Data System (ADS)

    Rodríguez de Fonseca, Belen; Mohino, Elsa; Mechoso, Carlos R.

    2015-04-01

    The Sahel experienced a severe drought during the 1970's and 1980's after wet periods in the 1950's and 1960's. Although rainfall partially recovered since the 1990's, the drought had devastating impacts on societies. Most studies agree that this dry period resulted primarily from remote effects of sea surface temperature (SST) anomalies amplified by local land surface/atmospheric interactions. This paper reviews advances made during the last decade to better understand the impact of global SST variability on West African rainfall at interanual to decadal time scales. At interanual time scales, a warming of the equatorial Atlantic and Pacific/Indian oceans results in rainfall reduction over the Sahel and positive SST anomalies over the Mediterranean sea tend to be associated with increased rainfall. At decadal time scales, a warming over the Tropics leads to drought over the Sahel, while the warming over the North Atlantic promotes increased rainfall. The skill of numerical forecasts has improved during the last decades, due to better dynamical vegetation schemes. Prediction systems have evolved from seasonal to decadal forecasting.The agreement among future projections has improved from CMIP3 to CMIP5, with a general tendency for slightly wetter conditions over central part, drier conditions over the western part and a delay in the monsoon onset. The role of the Indian ocean, the stationarity of teleconnections, the determination of the leader ocean basin in driving decadal variability, the antropogenic role, the reduction of the model rainfall spread and the improvement of some model components are among the most important remaining questions that will be the focus of current international projects.

  16. Decadal rainfall variability modes in observed rainfall records over East Africa and their relations to historical sea surface temperature changes

    NASA Astrophysics Data System (ADS)

    Omondi, P.; Awange, J. L.; Ogallo, L. A.; Okoola, R. A.; Forootan, E.

    2012-09-01

    SummaryDetailed knowledge about the long-term interface of climate and rainfall variability is essential for managing agricultural activities in Eastern African countries. To this end, the space-time patterns of decadal rainfall variability modes over East Africa and their predictability potentials using Sea Surface Temperature (SST) are investigated. The analysis includes observed rainfall data from 1920 to 2004 and global SSTs for the period 1950-2004. Simple correlation, trend and cyclical analyses, Principal Component Analysis (PCA) with VARIMAX rotation and Canonical Correlation Analysis (CCA) are employed. The results show decadal signals in filtered observed rainfall record with 10 years period during March-May (MAM) and October-December (OND) seasons. During June-August (JJA), however, cycles with 20 years period are common. Too much/little rainfall received in one or two years determines the general trend of the decadal mean rainfall. CCA results for MAM showed significant positive correlations between the VARIMAX-PCA of SST and the canonical component time series over the central equatorial Indian Ocean. Positive loadings were spread over the coastal and Lake Victoria regions while negative loading over the rest of the region with significant canonical correlation skills. For the JJA seasons, Atlantic SSTs had negative loadings centred on the tropical western Atlantic Ocean associated with the wet/dry regimes over western/eastern sectors. The highest canonical correlation skill between OND rainfall and the Pacific SSTs showed that El Niño/La Niña phases are associated with wet/dry decades over the region.

  17. Twenty Years of High-Resolution Sea Surface Temperature Imagery around Australia: Inter-Annual and Annual Variability

    PubMed Central

    Foster, Scott D.; Griffin, David A.; Dunstan, Piers K.

    2014-01-01

    The physical climate defines a significant portion of the habitats in which biological communities and species reside. It is important to quantify these environmental conditions, and how they have changed, as this will inform future efforts to study many natural systems. In this article, we present the results of a statistical summary of the variability in sea surface temperature (SST) time-series data for the waters surrounding Australia, from 1993 to 2013. We partition variation in the SST series into annual trends, inter-annual trends, and a number of components of random variation. We utilise satellite data and validate the statistical summary from these data to summaries of data from long-term monitoring stations and from the global drifter program. The spatially dense results, available as maps from the Australian Oceanographic Data Network's data portal (http://www.cmar.csiro.au/geonetwork/srv/en/metadata.show?id=51805), show clear trends that associate with oceanographic features. Noteworthy oceanographic features include: average warming was greatest off southern West Australia and off eastern Tasmania, where the warming was around 0.6°C per decade for a twenty year study period, and insubstantial warming in areas dominated by the East Australian Current, but this area did exhibit high levels of inter-annual variability (long-term trend increases and decreases but does not increase on average). The results of the analyses can be directly incorporated into (biogeographic) models that explain variation in biological data where both biological and environmental data are on a fine scale. PMID:24988444

  18. Temperature variability at Dürres Maar, Germany during the migration period and at high medieval times, inferred from stable carbon isotopes of Sphagnum cellulose

    NASA Astrophysics Data System (ADS)

    Moschen, R.; Kühl, N.; Peters, S.; Vos, H.; Lücke, A.

    2011-02-01

    This paper presents a high resolution reconstruction of local growing season temperature (GST) anomalies at Dürres Maar, Germany, spanning the last two millennia. The GST anomalies were derived from a stable carbon isotope time series of cellulose chemically extracted from Sphagnum leaves (?13Ccellulose) separated from a kettle-hole peat deposit of several metres thickness. The temperature reconstruction is based on the Sphagnum ?13Ccellulose /temperature dependency observed in calibration studies. Reconstructed GST anomalies show considerable centennial and decadal scale variability. A cold and presumably also wet phase with below-average temperature is reconstructed between the 4th and 7th century AD which is in accordance with the so called European Migration Period marking the transition from the Late Roman Period to the Early Middle Ages. At High Medieval Times above-average temperatures are obvious followed by a temperature decrease. On the contrary, a pronounced Late Roman Climate Optimum, often described as similar warm or even warmer as medieval times, could not be detected. The temperature signal of the Little Ice Age (LIA) is not preserved in Dürres Maar due to considerable peat cutting that takes place in the first half of the 19th century. The local GST anomalies show a remarkable agreement to northern hemispheric temperature reconstructions based on tree-ring data sets and are also in accordance with climate reconstructions on the basis of lake sediments, glacier advances and retreats, and historical data sets. Most notably, e.g. during the Early Middle Ages and at High Medieval Times, temperatures were not low or high in general. Rather high frequency temperature variability with multiple narrow intervals of below- and above-average temperatures at maximum lasting a few decades are reconstructed. Especially the agreements between our estimated GST anomalies and the NH temperature reconstructions derived from tree-ring chronologies indicate the great potential of Sphagnum leaves ?13Ccellulose time series from peat deposits for palaeoclimate research. This is particularly the case, given that a quantitative ?13Ccellulose/temperature relationship has been found for several Sphagnum species. Although the time resolution of Sphagnum ?13Ccellulose data sets certainly wouldn't reach the annual resolution of tree-ring data, reconstructions of past temperature variability on the basis of this proxy hold one particular advantage: due to often relatively high peat accumulation rates, especially in kettle-hole bogs accumulated on temperate latitudes over periods of up to several millennia, they allow extending temperature reconstructions based on tree-ring series into the past to enhance our knowledge of natural climate variability during the Holocene.

  19. The paradox of cooling streams in a warming world: regional climate trends do not parallel variable local trends in stream temperature in the Pacific continental United States

    USGS Publications Warehouse

    Arismendi, Ivan; Johnson, Sherri; Dunham, Jason B.; Haggerty, Roy; Hockman-Wert, David

    2012-01-01

    Temperature is a fundamentally important driver of ecosystem processes in streams. Recent warming of terrestrial climates around the globe has motivated concern about consequent increases in stream temperature. More specifically, observed trends of increasing air temperature and declining stream flow are widely believed to result in corresponding increases in stream temperature. Here, we examined the evidence for this using long-term stream temperature data from minimally and highly human-impacted sites located across the Pacific continental United States. Based on hypothesized climate impacts, we predicted that we should find warming trends in the maximum, mean and minimum temperatures, as well as increasing variability over time. These predictions were not fully realized. Warming trends were most prevalent in a small subset of locations with longer time series beginning in the 1950s. More recent series of observations (1987-2009) exhibited fewer warming trends and more cooling trends in both minimally and highly human-influenced systems. Trends in variability were much less evident, regardless of the length of time series. Based on these findings, we conclude that our perspective of climate impacts on stream temperatures is clouded considerably by a lack of long-termdata on minimally impacted streams, and biased spatio-temporal representation of existing time series. Overall our results highlight the need to develop more mechanistic, process-based understanding of linkages between climate change, other human impacts and stream temperature, and to deploy sensor networks that will provide better information on trends in stream temperatures in the future.

  20. Lower ionosphere monitoring by the South America VLF Network (SAVNET): C region occurrence and atmospheric temperature variability

    NASA Astrophysics Data System (ADS)

    Bertoni, Fernando Celso Perin; Raulin, Jean-Pierre; Gavilán, Hernán. Rivero; Kaufmann, Pierre; Rodriguez, Rodolfo; Clilverd, Mark; Cardenas, Jorge Samanes; Fernandez, Germán.

    2013-10-01

    profiles of phase measurements as observed on fixed VLF paths generally show a transient phase advance, followed by a phase delay, for about 90 min after sunrise hours. This is indicative of a reflecting ionospheric C region developing along the terminator line at an altitude below the normal D region. The suggested occurrence of a C region is consistent with rocket measurements made in the 1960s, showing a maximum of the electron density between 64 and 68 km, and by radio sounding in the 1980s. In order to correctly describe the properties of the phase effect associated with the presence of a C region, it is important to understand the subionospheric propagation characteristics of the VLF paths. In this paper, we analyze the variations presented by the temporal properties of the VLF narrowband phase effect and determined a parameter associated with the appearance of the C region at sunrise hours observed by receivers from the South America VLF Network. Periodic patterns emerge from the parameter curves. Two distinct temporal behavior regimes can be identified: one exhibiting slow variations between March and October, and another one exhibiting faster variations between October and March. Solar illumination conditions and the geometrical configuration of the VLF paths relative to the sunrise terminator partly explain the slow variation regime. During periods of faster variations, we have observed good association with atmospheric temperature variability found in the measurements of the Thermosphere Ionosphere Mesosphere Energetics and Dynamics and Sounding of the Atmosphere using Broadband Emission Radiometry satellite instrument, which we assume to be related to the winter anomaly atmospheric phenomenon. However, when comparing the parameter time series with temperature curves, no direct one-to-one correspondence was found for transient events.

  1. Enhanced Vertical Atmosphere Resolution improves Climate Model Simulation of Tropical Atlantic Sea Surface Temperature and Interannual Variability

    NASA Astrophysics Data System (ADS)

    Harlass, Jan; Latif, Mojib; Park, Wonsun

    2015-04-01

    A long-standing problem in climate modelling is the inaccurate simulation of tropical Atlantic (TA) sea surface temperature (SST), known as the TA SST bias. Basically all state-of-the-art global climate models suffer from a reversed equatorial zonal SST gradient in the Atlantic and too warm surface temperatures in the Benguela upwelling region. These biases have far-reaching consequences for climate prediction as they go along, among others, with erroneous precipitation patterns. We used the coupled atmosphere-ocean-sea ice Kiel Climate Model (KCM) to conduct experiments with varying atmosphere model resolutions, while keeping the ocean component unchanged. Atmosphere model resolution has been increased not only in the horizontal (from T42 to T159), but also in the vertical (from L31 to L62). We show that the TA SST bias can be largely reduced by increasing both the atmospheric horizontal and vertical resolution. In particular, the zonal SST gradient along the equator is simulated with the correct sign. At high horizontal resolution, enhanced vertical resolution is indispensable to substantially improve the simulation of TA SST by enhancing the surface wind stress. This also reduces biases in the upper ocean thermal structure and precipitation. A major step forward is a more northward position of the Intertropical Convergence Zone. Although enhanced horizontal resolution alone leads to some improvement in the mean climate, typical bias patterns, characterized by a reversed zonal SST gradient at the equator and too warm SST along the Benguela Coast, remain. Notable changes in the pattern of interannual SST variability occur with increased resolution. Seasonal phase locking is captured only at high vertical resolution, although a phase lag of 2 months still exists. Our study highlights the importance of sufficiently high atmospheric model resolution and, equally important, a consistent choice of horizontal and vertical model resolution.

  2. Wettability of poultry litter biochars at variable pyrolysis temperatures and their impact on soil wettability and water retention relationships

    NASA Astrophysics Data System (ADS)

    Yi, S. C.; Witt, B.; Guo, M.; Chiu, P.; Imhoff, P. T.

    2012-12-01

    To reduce the impact of poultry farming on greenhouse gas emissions, poultry farming waste - poultry litter - can be converted to biofuel and biochar through slow-pyrolysis, with the biochar added to agricultural soil for nutrient enrichment and carbon sequestration. While biochars from source materials other than poultry litter have been shown to sequester carbon and increase soil fertility, there is considerable variability in biochar behavior - even with biochars created from the same source material. This situation is exacerbated by our limited understanding of how biochars alter physical, chemical, and biological processes in agricultural soils. The focus of this work is to develop a mechanistic understanding of how poultry litter (PL) biochars affect the hydrology, microbial communities, N2O emissions, and nitrogen cycling in agricultural soils. The initial focus is on the impact of PL biochar on soil hydrology. PL from Perdue AgriRecycle, LLC (Seaford, Delaware) was used to produce biochars at pyrolysis temperatures from 300°C to 600°C. To explore the impact of these biochars on soil wettability, the PL biochars were mixed with a 30/40 Accusand in mass fractions from 0% to 100%. The water contact angle was then measured using a goniometer on these sand/biochar mixtures using the sessile drop method and a single layer of sample particles. The PL biochars produced at temperatures between 300°C to 400°C were hydrophobic, while those pyrolized at > 400°C were hydrophilic. Water contact angles for samples with 100% biochar varied systematically with pyrolysis temperature, decreasing from 101.12° to 20.57° as the pyrolysis temperature increased from 300 to 600°C. Even for small amounts of hydrophobic biochar added to the hydrophilic sand, the contact angle of the mixture was altered: for sand/biochar mixtures containing only 2% hydrophobic PL biochar by weight, the contact angle of the mixture increased from ~ 8° (0% biochar) to 20° (2% biochar). For higher mass fractions, the impact of hydrophobic PL biochar on the sand/mixture contact angle was more dramatic: for a sand/biochar mixture with 15% PL biochar, the contact angle was 40.12°. Water drop penetration tests were also performed on these samples, and results were consistent with contact angles measured with the sessile drop method. To further explore the cause of the varying contact angle with pyrolysis temperature, the PL biochars were vigorously rinsed with deionized water or heated for 24 hours at 105°C, and the contact angle measurements repeated. Both rinsing and heating samples rendered hydrophobic PL biochar hydrophilic. Rinsate samples were analyzed for total organic carbon and with GC-MS. These data suggest that bio-oils produced during slow-pyrolysis at temperatures < 400°C condensed on biochar and caused hydrophobicity. These bio-oils could be removed through vigorous washing with deionized water or heating to 105°C. The implication of these changes in water contact angle from PL biochar addition on water retention relationships for soil and on water distribution within pores will be discussed.

  3. Temperature variability and trend estimates at tropopause and UT-LS over a subtropical site: Reunion (20.8° S, 55.5° E)

    NASA Astrophysics Data System (ADS)

    Bègue, N.; Bencherif, H.; Sivakumar, V.; Kirgis, G.; Mzé, N.; Leclair de Bellevue, J.

    2010-04-01

    This paper mainly focuses on the trends and variability of the tropopause and UT-LS temperature using radiosonde observations carried out over 16 years (January 1993 to December 2008) from a southern subtropical site, Reunion Island (20.8° S, 55.5° E), using a linear-regression fitting model. Two kinds of tropopause definitions, namely, cold point tropopause (CPT) and lapse rate tropopause (LRT) are used. In the purpose to characterize and quantify the relationship between the regional oceanic forcing and temperature at tropopause and UT-LS, we take into account the Indian Ocean Dipole (IOD) for the estimation of temperature trends. Results show that the main component is the Annual Oscillation (AO), particularly at tropopause (CPT, LRT) and in the lower stratosphere (LS) where more than 26% of the variability of temperature can be explained by AO. As a result, the influence of IOD on the variability of the temperature is at highest ratio at CPT and LS, with respectively 12.3% and 13.1%. The results show a low correlation between IOD and the temperature anomalies at tropopause (LRT, CPT) and UT-LS, in the range of 0.08-0.15, with the maximum of correlation at CPT (0.15). In addition, trend estimates at CPT and in the LS suggests that the IOD forcing contributes enhancing the rate of cooling of about 0.1 K per decade. Indeed a trend analysis reveals a cooling of about 0.90±0.40 K per decade at LS and a cooling trend of about 0.36±0.48 K per decade at CPT. The cooling trend at LS is found to be in good agreement with the others studies. These results support the assumption that the Indian Ocean may have a slight impact on temperature variability and on temperature change at CPT and in the LS over Reunion.

  4. A day-to-day comparison study of Seasat scatterometer winds with winds observed from islands in the tropical Pacific

    NASA Technical Reports Server (NTRS)

    Davison, Jerry; Harrison, D. E.

    1989-01-01

    The winds derived from the Seasat-A Satellite Scatterometer (SASS) measurements have been the subject of great interest since the 1978 mission, because of the promise of radically improved wind observations over the world ocean. Due to the early end of the mission, only a few of the planned ground truth validation experiments could be made, and the subsequent lack of sufficient high quality independent wind data for comparison has limited the ability to resolve critical issues regarding the scatterometer's performance and the correct interpretation of its signal. Operational weather observations were made of ocean winds independent of Seasat mission plans during the Seasat mission period; the results are reported of a comparison study using such observations. Previous verification with in situ winds has been primarily in middle latitudes (GOASEX, JASIN, and NDBO buoys); winds observed from nine tropical Pacific islands are compared with nearly contemporaneous measurements taken by SASS during overpasses of the islands.

  5. Integration in Italian Schools: Teachers' Perceptions Regarding Day-to-Day Practice and Its Effectiveness

    ERIC Educational Resources Information Center

    Ianes, Dario; Demo, Heidrun; Zambotti, Francesco

    2014-01-01

    Italy is famous for having the highest percentage of students with disabilities attending "the school for all" (integration). However, in recent studies, the reality of integration seems to be more complex. Integration has reached some important goals (e.g. longer school careers), but while the Italian school system envisages the full…

  6. Health care professionals’ understanding and day-to-day practice of patient empowerment in diabetes; time to pause for thought?

    Microsoft Academic Search

    K. Asimakopoulou; P. Newton; A. J. Sinclair; S. Scambler

    This exploratory study examines what Health Care Professionals (HCPs) working with diabetes patients, understand by the term ‘empowerment’, their attitudes towards it and whether they believe they practise in ways consistent with empowerment principles. A small sample of diabetes HCPs (N=13), from National Health Service (NHS) hospital, walk-in and General Practitioner (GP) clinics in South-East England, was interviewed. In-depth semi-structured

  7. Building enterprise-wide resilience by integrating business continuity capability into day-to-day business culture and technology.

    PubMed

    Alesi, Patrick

    2008-04-01

    This paper follows the development of the business continuity planning (BCP) programme at Lehman Brothers following the events of September 11th. Previous attempts to implement a `traditional' form of BCP had been ineffective, but following the events, the firm began to look at BCP in a new light. This paper deals with three main themes: creating a culture of resiliency, leveraging technology, and building flexible plans. Distributing accountability for BCP to business line managers, integrating BCP change management into the normal course of business, and providing every employee with personalised BCP information breeds a culture of resiliency where people are empowered to react to events without burdensome, hierarchical response and recovery procedures. Building a strong relationship with one's application development community can result in novel, customised BCP solutions; existing systems and data structures can be used to enhance an existing BCP. Even the best plans are often challenged by events; understanding that flexibility is essential to effective incident response is a critical element in the development of a proper business continuity plan. PMID:21339108

  8. Explaining spatial patterns of sap flow: day-to-day shifts in relevance of site- and tree-specific controls

    NASA Astrophysics Data System (ADS)

    Hassler, Sibylle K.; Weiler, Markus; Blume, Theresa

    2015-04-01

    Transpiration is a key process in the hydrological cycle and a sound understanding and quantification of transpiration is essential for management decisions and for hydrological and climatological modelling. To assess transpiration at the tree scale sap flow velocity is commonly measured. Besides atmospheric conditions and soil moisture state, tree-specific characteristics such as species, size or social status control sap flow of individual trees. Within forest stands, properties such as species composition, basal area or stem number also affect sap flow via competition or facilitation mechanisms. Finally, sap flow patterns might also be influenced by landscape-scale characteristics such as geology, slope position or aspect because they affect water and energy availability; however, so far little is known about these larger-scale controls. We studied the relative importance of various tree- and site-specific characteristics with linear statistical models for daily sap velocity observations on 38 trees at 12 locations in mixed beech and oak forests in a catchment in Luxemburg. The temporal variation of the predictors' importance for sap velocity patterns was then related to hydro-meteorological conditions. Results indicate that a combination of tree- and site-specific controls influence sap velocity patterns, namely tree species, tree diameter, stand basal area, geology and aspect. The temporal dynamics of these controls are related to hydro-meteorological conditions, with tree-specific controls dominating when the atmospheric gradient is strong, i.e. the vapour pressure deficit is large, leading to higher sap velocities, whereas landscape-scale site characteristics are more important during weak atmospheric gradients. The importance of individual predictors also varies between spring and summer, probably due to different soil moisture and atmospheric conditions of the two periods. We conclude that both tree- and site-specific characteristics control sap velocity patterns and the temporal dynamics of their importance is dependent on hydro-meteorological conditions. Thus, transpiration estimates at the landscape scale should on the one hand consider hydro-meteorological conditions and tree characteristics, but on the other hand should also include site characteristics such as geology and aspect in order to improve the spatial representation and prediction of hydrological processes.

  9. Power applications of high-temperature superconductivity: Variable speed motors, current switches, and energy storage for end use

    SciTech Connect

    Hawsey, R.A. [Oak Ridge National Lab., TN (United States); Banerjee, B.B.; Grant, P.M. [Electric Power Research Inst., Palo Alto, CA (United States)

    1996-08-01

    The objective of this project is to conduct joint research and development activities related to certain electric power applications of high-temperature superconductivity (HTS). The new superconductors may allow development of an energy-efficient switch to control current to variable speed motors, superconducting magnetic energy storage (SMES) systems, and other power conversion equipment. Motor types that were considered include induction, permanent magnet, and superconducting ac motors. Because it is impractical to experimentally alter certain key design elements in radial-gap motors, experiments were conducted on an axial field superconducting motor prototype using 4 NbTi magnets. Superconducting magnetic energy storage technology with 0.25--5 kWh stored energy was studied as a viable solution to short duration voltage sag problems on the customer side of the electric meter. The technical performance characteristics of the device wee assembled, along with competing technologies such as active power line conditioners with storage, battery-based uninterruptible power supplies, and supercapacitors, and the market potential for SMES was defined. Four reports were prepared summarizing the results of the project.

  10. Investigation of the rate-controlling mechanism(s) for high temperature creep and the relationship between creep and melting by use of high pressure as a variable

    SciTech Connect

    Not Available

    1991-01-01

    Using high pressure as a variable, the rate-controlling mechanism for high temperature creep and the relationship between creep and melting is investigated for silicon and nickel. An apparatus is used in which the samples are heated to melting point and subjected to 1 to 3 GigaPascal pressure. The stress behavior of the materials are then studied.

  11. Recruitment variability in Baltic Sea sprat ( Sprattus sprattus ) is tightly coupled to temperature and transport patterns affecting the larval and early juvenile stages

    Microsoft Academic Search

    H. Baumann; H.-H. Hinrichsen; C. Möllmann; F. W. Köster; A. M. Malzahn; A. Temming

    2006-01-01

    Recruitment patterns of Baltic Sea sprat (Sprattus sprattus) were correlated to time series of (i) month- and depth-specific temperature conditions and (ii) larval drift patterns inferred from long-term Lagrangian particle simula- tions. From the latter, we derived an index that likely reflected the variable degree of annual larval transport from the central, deep spawning basins to the shallow coastal areas

  12. Observed seasonal variability of heat content in the upper layers of the tropical Indian Ocean from a new global ocean temperature climatology

    Microsoft Academic Search

    R. R. Rao; R. Sivakumar

    1998-01-01

    A subset of the recently published temperature climatology for the global oceans is utilized to characterize the observed seasonal variability in the heat content (HC) of the upper layers, estimated from surface to fixed depths (50, 100, 200 and 300m), and with respect to fixed isotherm (27, 26, 25 and 20°C) depths, for the entire tropical Indian Ocean (TIO). The

  13. Intraannual variability of tides in the thermosphere from model simulations and in situ satellite observations

    NASA Astrophysics Data System (ADS)

    Häusler, K.; Hagan, M. E.; Forbes, J. M.; Zhang, X.; Doornbos, E.; Bruinsma, S.; Lu, G.

    2015-01-01

    In this paper, we provide insights into limitations imposed by current satellite-based strategies to delineate tidal variability in the thermosphere, as well as the ability of a state-of-the-art model to replicate thermospheric tidal determinations. Toward this end, we conducted a year-long thermosphere-ionosphere-mesosphere-electrodynamics general circulation model (TIME-GCM) simulation for 2009, which is characterized by low solar and geomagnetic activity. In order to account for tropospheric waves and tides propagating upward into the ˜30-400 km model domain, we used 3-hourly MERRA (Modern-Era Retrospective Analysis for Research and Application) reanalysis data. We focus on exospheric tidal temperatures, which are also compared with 72 day mean determinations from combined Challenging Minisatellite Payload (CHAMP) and Gravity Recovery and Climate Experiment (GRACE) satellite observations to assess the model's capability to capture the observed tidal signatures and to quantify the uncertainties associated with the satellite exospheric temperature determination technique. We found strong day-to-day tidal variability in TIME-GCM that is smoothed out when averaged over as few as ten days. TIME-GCM notably overestimates the 72 day mean eastward propagating tides observed by CHAMP/GRACE, while capturing many of the salient features of other tidal components. However, the CHAMP/GRACE tidal determination technique only provides a gross climatological representation, underestimates the majority of the tidal components in the climatological spectrum, and moreover fails to characterize the extreme variability that drives the dynamics and electrodynamics of the ionosphere-thermosphere system. A multisatellite mission that samples at least six local times simultaneously is needed to provide this quantification.

  14. Model performance of a biomass-fueled power station with variable furnace exit gas temperature to control fouling deposition

    NASA Astrophysics Data System (ADS)

    Yomogida, David Edwin

    A major problem associated with the utilization of any biomass fuel in direct-combustion energy production is fouling (ash deposition on boiler surfaces) and the related issue of slagging, resulting from transformations among the inorganic constituents of the fuel. These deposits reduce heat transfer from the fire- to water-side, reducing power plant efficiency and necessitating the design of more tolerant heat exchange equipment. Wood: currently serves as the major source of fuel in biomass conversion to energy because of its more general availability, and it suffers less from fouling and slagging than many other biomass fuels such as rice straw. To reduce fouling severity, furnace exit gas temperature (FEGT) may be decreased to solidify ash ahead of superheaters and other heat exchanger equipment. Thermal and economic computer models of a direct-combustion Rankine cycle power plant were developed to predict the impact of variable FEGT and overall heat transfer coefficient on power plant efficiency and economy. No attempt was made to model the fire-side processes leading to the formation of fouling deposits. A base case: operational and economic profile of a biomass power plant was established, and models, were executed using these parameters, approximating a power plant efficiency of 19.9% and a cost of electricity (COE) of 0.0636 kWh-1 (including capital costs). If no capital, costs are included, then COE is 0.0205 kWh-1. Sensitivity analyses were performed on power plant efficiency and COE. Changes in FEGT through variable excess air resulted in substantial sensitivity in power plant efficiency (plant efficiency of 21.4% for FEGT of 1030°C (5% excess air) and 18.7% for 924°C (55% excess air)). Plant efficiency was determined to be moderately sensitive to changes in overall heat transfer coefficient on the secondary superheater (18.7% for no heat transfer through secondary superheater and 19.9% for base case heat transfer). Fouling scenarios showed that FEGT may be reduced by reducing steaming rate (20% reduction in steaming rate, FEGT of 939°C), but the reduction in steaming rate increased COE if the COE included capital costs (11.5% increase). However, if capital costs were not included, then COE may decrease (6.8% reduction).

  15. Inter-Decadal to Multi-Decadal Sea Surface Temperature Variability in the Southwest Tropical Pacific Since AD 1648

    NASA Astrophysics Data System (ADS)

    Delong, K. L.; Quinn, T. M.; Taylor, F. W.; Lin, K.; Shen, C.

    2008-12-01

    The southwest tropical Pacific is a region with temporally and spatially sparse sea surface temperature (SST) records that limit investigations of climate variability on interannual to centennial time scales for this region. We present a monthly resolved coral Sr/Ca record from 1648 to 1999 from Amédée Island, New Caledonia (22.48°S, 166.47°E), and reconstruct SST variability in the southwest Pacific for the past 350 years. The coral Sr/Ca record was assembled from two 3-m long coeval cores from the same massive Porites lutea coral colony. The chronology is based on annual density-band counting, cross- correlation of the two intracolony coral Sr/Ca records, and 11 230Th dates with 2? precision of ±1.1 to 16.5 years. The intracolony coral Sr/Ca variations are reproducible for more than three centuries (average monthly misfit error = ±0.015 mmol/mol; ~0.28°C), and the intracolony variations are coherent from interannual to centennial periodicities. The SST reconstructed from coral Sr/Ca shows a cooling trend from AD 1740 to 1815, a cold 19th century (~0.6°C with respect to AD 1967 to 1992), followed by a warming trend into the 20th century. Many of the cold events in the coral Sr/Ca record coincide with large volcanic eruptions (e.g., Tambora AD 1815 and Krakatau AD 1883). Spectral analysis reveals the record is dominated by modulating inter-decadal (14 to 21 years) periodicities and quasi-persistent multi-decadal (24 to 38 years) periodicities that do not exhibit coherence with the Pacific Decadal Oscillation (PDO) or the Inter-decadal Pacific Oscillation (IPO). Wavelet analysis reveals that the inter-decadal periodicities coincide with large volcanic eruptions, and the 55- to 70-year periodicities are coeval with volcanic cooling and warming trends in the 19th and 20th centuries. The multi-decadal periodicities may be a harmonic of the modulating inter-decadal periodicities or may represent an independent mode not previously recognized in the southwest Pacific.

  16. A method for infrared temperature measurements of thin film materials with a low, unknown, and/or variable emissivity at low temperatures

    E-print Network

    Jarboe, Jason Neal

    2013-01-01

    Accurate non-contact temperature measurements of objects using thermal radiation is often limited by low emission of IR radiation because of low temperatures and/or emissivities, or by the unknown or changing emissivity ...

  17. Robust influences of superparameterized rainfall variability and intensity on land-atmosphere energetics including soil moisture, surface fluxes, and temperature

    NASA Astrophysics Data System (ADS)

    Kooperman, Gabriel; Pritchard, Michael

    2015-04-01

    Land-atmosphere coupling energetics can play critical roles in mediating local weather and climate. Interactions at this hydrologic interface impact the availability of freshwater, droughts, floods, and temperature extremes. Predicting how the hydrological cycle will respond to climate change requires a realistic representation of these complex energy exchange mechanisms in global climate models (GCMs). Conventional GCMs suggest that regions of strong coupling (i.e. where local rainfall and soil moisture fluctuations are correlated) will be most sensitive to climate change. However, these models do not capture some forms of organized convection and are known to distort the diurnal character of rainfall over land. Second-order characteristics of rainfall (variability, frequency, timing, and intensity), in addition to time-integrated climatology, can have a significant impact on the hydrologic cycle. They determine whether rainwater infiltrates the soil or runs off the surface and how much water collected on the vegetation canopy is available for re-evaporation. Here we investigate land-atmosphere interactions in a GCM that explicitly resolves convection, captures organized storms, and improves the diurnal cycle and intensity distribution of rain. In this multi-scale modeling approach called super-parameterization (SP), simplified cloud resolving models are embedded in each grid column of the NCAR Community Atmosphere Model (CAM) to replace conventional parameterizations. SP-CAM captures the broad rainfall intensity distribution and extreme events that are missing in conventional CAM, especially during the mid-latitude summer and in the tropics, exerting a strong influence during the growing season. More intense rainfall reduces canopy interception (and the re-evaporation of rainwater that is often exaggerated in GCMs), increases the rate of rainfall reaching the ground and thus running off the surface, and generally increases the demand on transpiration. As a result, SP-CAM amplifies the Bowen ratio relative to conventional CAM, which is enhanced further with climate change. This amplified Bowen ratio appears to be a robust effect of SP. It is consistent across many regions and model versions with different resolution, cloud microphysics, and land-surface processes, broadening the temperature distribution to include more extreme heat events in SP-CAM.

  18. Temperature variability and trends in the UT-LS over a subtropical site: Reunion (20.8° S, 55.5° E)

    NASA Astrophysics Data System (ADS)

    Bègue, N.; Bencherif, H.; Sivakumar, V.; Kirgis, G.; Mze, N.; Leclair de Bellevue, J.

    2010-09-01

    This paper mainly focuses on the trends and variability of the UT-LS temperature using radiosonde observations carried out over 16 years (January 1993 to December 2008) from a southern subtropical site, Reunion (20.8° S, 55.5° E), using a linear-regression fitting model. Two kinds of tropopause definitions, namely, cold point tropopause (CPT) and lapse rate tropopause (LRT) are used. In order to characterize and quantify the relationship between regional oceanic forcing and temperature at UT-LS, we took into account the Indian Ocean Dipole (IOD) for the estimation of temperature trends. Results show that the main component is the Annual Cycle (AC), particularly at tropopause (CPT, LRT) and in the lower stratosphere (LS) where more than 26.0±2.4% of temperature variability can be explained by AC. The influence of IOD on the variability of the temperature is at highest ratio at CPT and LS, with respectively 12.3±7.3% and 13.1±5.9%. The correlations between IOD and temperature anomalies at UT-LS are barely significant, which are found to be in close agreement with the results obtained by Rosenlof et al. (2008) over the western tropical Pacific Ocean. The temperature trend in the LS reveals a cooling of about -0.90±0.40 K per decade. The cooling trend at LS is found to be in close agreement with the others studies. Trend estimates in the LS suggest that IOD forcing contributes to increasing cooling by about 0.16±0.05 K per decade. Past works have shown that the additional carbon dioxide increase has a minor effect in the LS, and suggested that other effects than ozone and carbon dioxide changes have to be considered, in order to explain the observed temperature changes in the LS. From this study, we can suggest that the SST changes can be considered also, in addition to effects due to ozone and carbon dioxide changes, in order to explain the observed temperature changes in the LS. As a consequence, our results support the assumption that the Indian Ocean may have a slight impact on temperature variability and on temperature change in the LS over Reunion.

  19. Collaborative Research: Process-Resolving Decomposition of the Global Temperature Response to Modes of Low Frequency Variability in a Changing Climate

    SciTech Connect

    Deng, Yi

    2014-11-24

    DOE-GTRC-05596 11/24/2104 Collaborative Research: Process-Resolving Decomposition of the Global Temperature Response to Modes of Low Frequency Variability in a Changing Climate PI: Dr. Yi Deng (PI) School of Earth and Atmospheric Sciences Georgia Institute of Technology 404-385-1821, yi.deng@eas.gatech.edu El Niño-Southern Oscillation (ENSO) and Annular Modes (AMs) represent respectively the most important modes of low frequency variability in the tropical and extratropical circulations. The projection of future changes in the ENSO and AM variability, however, remains highly uncertain with the state-of-the-science climate models. This project conducted a process-resolving, quantitative evaluations of the ENSO and AM variability in the modern reanalysis observations and in climate model simulations. The goal is to identify and understand the sources of uncertainty and biases in models’ representation of ENSO and AM variability. Using a feedback analysis method originally formulated by one of the collaborative PIs, we partitioned the 3D atmospheric temperature anomalies and surface temperature anomalies associated with ENSO and AM variability into components linked to 1) radiation-related thermodynamic processes such as cloud and water vapor feedbacks, 2) local dynamical processes including convection and turbulent/diffusive energy transfer and 3) non-local dynamical processes such as the horizontal energy transport in the oceans and atmosphere. In the past 4 years, the research conducted at Georgia Tech under the support of this project has led to 15 peer-reviewed publications and 9 conference/workshop presentations. Two graduate students and one postdoctoral fellow also received research training through participating the project activities. This final technical report summarizes key scientific discoveries we made and provides also a list of all publications and conference presentations resulted from research activities at Georgia Tech. The main findings include: 1) the distinctly different roles played by atmospheric dynamical processes in establishing surface temperature response to ENSO at tropics and extratropics (i.e., atmospheric dynamics disperses energy out of tropics during ENSO warm events and modulate surface temperature at mid-, high-latitudes through controlling downward longwave radiation); 2) the representations of ENSO-related temperature response in climate models fail to converge at the process-level particularly over extratropics (i.e., models produce the right temperature responses to ENSO but with wrong reasons); 3) water vapor feedback contributes substantially to the temperature anomalies found over U.S. during different phases of the Northern Annular Mode (NAM), which adds new insight to the traditional picture that cold/warm advective processes are the main drivers of local temperature responses to the NAM; 4) the overall land surface temperature biases in the latest NCAR model (CESM1) are caused by biases in surface albedo while the surface temperature biases over ocean are related to multiple factors including biases in model albedo, cloud and oceanic dynamics, and the temperature biases over different ocean basins are also induced by different process biases. These results provide a detailed guidance for process-level model turning and improvement, and thus contribute directly to the overall goal of reducing model uncertainty in projecting future changes in the Earth’s climate system, especially in the ENSO and AM variability.

  20. Daily scale winter-time sea surface temperature variability and the Iberian Poleward Current in the southern Bay of Biscay from 1981 to 2010

    NASA Astrophysics Data System (ADS)

    Esnaola, G.; Sáenz, J.; Zorita, E.; Fontán, A.; Valencia, V.; Lazure, P.

    2012-12-01

    The combination of remotely sensed gappy sea surface temperature (SST) images with the missing data filling Data Interpolating EOFs (DINEOF) technique followed by a Principal Component Analysis of the reconstructed data, has been used to identify the time evolution and the daily scale variability of the winter-time surface signal of the Iberian Poleward Current (IPC) during the 1981-2010 period. An exhaustive comparison with the existing bibliography, and the vertical temperature and salinity profiles related to its extremes over the Bay of Biscay area, show that the obtained time series accurately reflect the variability of the IPC. A physical mechanism involving both atmospheric and oceanic variables is proposed in relation to the variability of the IPC. It jointly takes into account several mechanisms that have separately been related to the variability of the IPC, i.e. the south-westerly winds, the Joint Effect of Baroclinicity And Relief (JEBAR) effect, the topographic ? effect and a weakened North Atlantic Gyre. This mechanism emerges from an atmospheric 500 hPa circulation anomaly that has not a simple relationship with any of the most common North Atlantic teleconnection patterns. It then generates mutually coherent SST and sea level anomaly patterns in the North Atlantic area due to the action of anomalous wind-stress and heat-fluxes, and locally, it also generates the conditions for the mentioned mechanisms in the Bay of Biscay area.

  1. Modeling temporal and large-scale spatial variability of soil respiration from soil water availability, temperature and

    E-print Network

    Yakir, Dan

    Modeling temporal and large-scale spatial variability of soil respiration from soil water 2003. [1] Field-chamber measurements of soil respiration from 17 different forest and shrubland sites seasonal, interannual and spatial variability of soil respiration as affected by water availability

  2. Identifying Signatures of Natural Climate Variability in Time Series of Global-Mean Surface Temperature: Methodology and Insights

    E-print Network

    fluctuations exhibit a complicated spatial signature with largest-amplitude sea surface temperature February 2009, in final form 23 May 2009) ABSTRACT Global-mean surface temperature is affected by both-mean surface temperature reflects the combined influences of naturally occurring climate variations

  3. Two-temperature accretion flows in magnetic cataclysmic variables: Structures of post-shock emission regions and X-ray spectroscopy

    E-print Network

    Curtis Saxton; Kinwah Wu; Mark Cropper; Gavin Ramsay

    2005-04-12

    We use a two-temperature hydrodynamical formulation to determine the temperature and density structures of the post-shock accretion flows in magnetic cataclysmic variables (mCVs) and calculate the corresponding X-ray spectra. The effects of two-temperature flows are significant for systems with a massive white dwarf and a strong white-dwarf magnetic field. Our calculations show that two-temperature flows predict harder keV spectra than one-temperature flows for the same white-dwarf mass and magnetic field. This result is insensitive to whether the electrons and ions have equal temperature at the shock but depends on the electron-ion exchange rate, relative to the rate of radiative loss along the flow. White-dwarf masses obtained by fitting the X-ray spectra of mCVs using hydrodynamic models including the two-temperature effects will be lower than those obtained using single-temperature models. The bias is more severe for systems with a massive white dwarf.

  4. MOnthly TEmperature DAtabase of Spain 1951-2010: MOTEDAS (2): The Correlation Decay Distance (CDD) and the spatial variability of maximum and minimum monthly temperature in Spain during (1981-2010).

    NASA Astrophysics Data System (ADS)

    Cortesi, Nicola; Peña-Angulo, Dhais; Simolo, Claudia; Stepanek, Peter; Brunetti, Michele; Gonzalez-Hidalgo, José Carlos

    2014-05-01

    One of the key point in the develop of the MOTEDAS dataset (see Poster 1 MOTEDAS) in the framework of the HIDROCAES Project (Impactos Hidrológicos del Calentamiento Global en España, Spanish Ministery of Research CGL2011-27574-C02-01) is the reference series for which no generalized metadata exist. In this poster we present an analysis of spatial variability of monthly minimum and maximum temperatures in the conterminous land of Spain (Iberian Peninsula, IP), by using the Correlation Decay Distance function (CDD), with the aim of evaluating, at sub-regional level, the optimal threshold distance between neighbouring stations for producing the set of reference series used in the quality control (see MOTEDAS Poster 1) and the reconstruction (see MOREDAS Poster 3). The CDD analysis for Tmax and Tmin was performed calculating a correlation matrix at monthly scale between 1981-2010 among monthly mean values of maximum (Tmax) and minimum (Tmin) temperature series (with at least 90% of data), free of anomalous data and homogenized (see MOTEDAS Poster 1), obtained from AEMEt archives (National Spanish Meteorological Agency). Monthly anomalies (difference between data and mean 1981-2010) were used to prevent the dominant effect of annual cycle in the CDD annual estimation. For each station, and time scale, the common variance r2 (using the square of Pearson's correlation coefficient) was calculated between all neighbouring temperature series and the relation between r2 and distance was modelled according to the following equation (1): Log (r2ij) = b*°dij (1) being Log(rij2) the common variance between target (i) and neighbouring series (j), dij the distance between them and b the slope of the ordinary least-squares linear regression model applied taking into account only the surrounding stations within a starting radius of 50 km and with a minimum of 5 stations required. Finally, monthly, seasonal and annual CDD values were interpolated using the Ordinary Kriging with a spherical variogram over conterminous land of Spain, and converted on a regular 10 km2 grid (resolution similar to the mean distance between stations) to map the results. In the conterminous land of Spain the distance at which couples of stations have a common variance in temperature (both maximum Tmax, and minimum Tmin) above the selected threshold (50%, r Pearson ~0.70) on average does not exceed 400 km, with relevant spatial and temporal differences. The spatial distribution of the CDD shows a clear coastland-to-inland gradient at annual, seasonal and monthly scale, with highest spatial variability along the coastland areas and lower variability inland. The highest spatial variability coincide particularly with coastland areas surrounded by mountain chains and suggests that the orography is one of the most driving factor causing higher interstation variability. Moreover, there are some differences between the behaviour of Tmax and Tmin, being Tmin spatially more homogeneous than Tmax, but its lower CDD values indicate that night-time temperature is more variable than diurnal one. The results suggest that in general local factors affects the spatial variability of monthly Tmin more than Tmax and then higher network density would be necessary to capture the higher spatial variability highlighted for Tmin respect to Tmax. The results suggest that in general local factors affects the spatial variability of Tmin more than Tmax and then higher network density would be necessary to capture the higher spatial variability highlighted for minimum temperature respect to maximum temperature. A conservative distance for reference series could be evaluated in 200 km, that we propose for continental land of Spain and use in the development of MOTEDAS.

  5. Ground surface temperatures (GST) modeling in the Russian Altay Mountains by using MODIS Land Surface Temperatures (LST). Assessment of the impact of snow cover, topography, landcover and sub-pixel variability on the GST-LST relationship.

    NASA Astrophysics Data System (ADS)

    van de Kerchove, Ruben; Goossens, Rudi

    2010-05-01

    The Russian Altay Mountains are a challenging area for large scale permafrost modeling. The lack of meteo-data, strong temperature-inversions, rapid changing snow cover patterns and complicated landcover demand an in-depth approach. As a solution, time and spatially covering MODIS land surface temperature (LST) might be used as a proxy replacing the interpolated air and ground surface temperatures (GST). Recent studies show the potential of this method on large continental areas (e.g. Canadian Arctic, Siberia), by using sinusoidal fits to eliminate the data-gaps both spatially as temporally out of the time-series. These studies use isotherms and analytical solutions for freezing and thawing to model permafrost distribution. However to use the LST-values as an upper boundary condition at heterogeneous mountain ranges as the Russian Altay, further research needs to be conducted. In detail the relation between this parameter and surface temperatures beneath areas covered with snow and vegetation requires more attention. In addition the effect of sub-pixel variability and topographic influence needs to be considered as the LST pixels come at 1km resolution. This study tries to answer these questions by showing results of 96 surface temperature time-series recorded in and around the valley of Dzhazator and on the Tarkhata plain (Kosh Agatch District) from July 2008 until July 2009, areas both characterized by discontinuous permafrost, together with spatial dynamics in LST, GST, snow cover and NDVI. iButtons and Onset dataloggers were installed in order to cover surface temperatures beneath a broad range of landcovers, different topographical positions and in grids to measure the sub-grid variability. LST time-series were interpolated by using the relationship with air temperatures. This enables to incorporate high frequency temperature variations in GST modeling. Correlations both for the summer as the winter season are presented between LST, GST, snow cover and NDVI (Normal Difference Vegetation Index) time-series. Sub-grid variability is examined by a combination of SPOT landcover classification (20m resolution), ASTER DEM (30m resolution) and multiple temperature observations in one MODIS pixel. Results show the potential of this method to model surface temperatures, and in a next step, permafrost, in areas without any other temperature observations, solely on satellite observations.

  6. Temperature

    NASA Technical Reports Server (NTRS)

    Berenson, P. J.; Robertson, W. G.

    1973-01-01

    The problems in human comfort in heat stress are emphasized, with less emphasis placed upon cold exposure problems. Physiological parameters related to human thermal interactions are discussed, as well as data concerning thermal protective clothing. The energy balance equation, heat transfer equation, thermal comfort, heat stress, and cold stress are also considered. A two node model of human temperature regulation in FORTRAN is appended.

  7. Terrestrial carbon sink observed from space: variation of growth rates and seasonal cycle amplitudes in response to interannual surface temperature variability

    NASA Astrophysics Data System (ADS)

    Schneising, O.; Reuter, M.; Buchwitz, M.; Heymann, J.; Bovensmann, H.; Burrows, J. P.

    2014-01-01

    The terrestrial biosphere is currently acting as a net carbon sink on the global scale, exhibiting significant interannual variability in strength. To reliably predict the future strength of the land sink and its role in atmospheric CO2 growth, the underlying biogeochemical processes and their response to a changing climate need to be well understood. In particular, better knowledge of the impact of key climate variables such as temperature or precipitation on the biospheric carbon reservoir is essential. It is demonstrated using nearly a decade of SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY) nadir measurements that years with higher temperatures during the growing season can be robustly associated with larger growth rates in atmospheric CO2 and smaller seasonal cycle amplitudes for northern mid-latitudes. We find linear relationships between warming and CO2 growth as well as seasonal cycle amplitude at the 98% significance level. This suggests that the terrestrial carbon sink is less efficient at higher temperatures during the analysed time period. Unless the biosphere has the ability to adapt its carbon storage under warming conditions in the longer term, such a temperature response entails the risk of potential future sink saturation via a positive carbon-climate feedback. Quantitatively, the covariation between the annual CO2 growth rates derived from SCIAMACHY data and warm season surface temperature anomaly amounts to 1.25 ± 0.32 ppm yr-1 K-1 for the Northern Hemisphere, where the bulk of the terrestrial carbon sink is located. In comparison, this relationship is less pronounced in the Southern Hemisphere. The covariation of the seasonal cycle amplitudes retrieved from satellite measurements and temperature anomaly is -1.30 ± 0.31 ppm K-1 for the north temperate zone. These estimates are consistent with those from the CarbonTracker data assimilated CO2 data product, indicating that the temperature dependence of the model surface fluxes is realistic.

  8. Preliminary analyses of the REMS Ground temperature data in Gale: exploring thermodynamic processes behind the diurnal variability

    NASA Astrophysics Data System (ADS)

    de la Torre Juárez, Manuel; Ramos, Miguel; Sebastian, Eduardo; Armiens, Carlos; Gómez-Elvira, Javier; Carrasco, Isaías; Haberle, Robert M.; Hamilton, Vicky E.; Jurado-Molina, Antonio; Lepinette, Alain; Martín-Torres, Javier; Martínez Frías, Jesús; Mischna, Michael; Mora, Luis; de Pablo, Miguel Angel; Peinado, Verónica; Rodríguez-Manfredi, José Antonio; Urqui O'Callahan, Roser; Vasavada, Ashwin R.; Zorzano Mier, María P.

    2013-04-01

    The Mars surface skin temperature monitored by the Ground Temperature Sensor on REMS, responds to solar forcing and the interactions between atmospheric, surface, and subterranean properties. We present the evolution of the minimum, maximum, and mean temperatures for the first 100 sols. We also give a brief description of the GTS performance. Finally we explore how the diurnal cycle of ground temperatures relates to energy fluxes due to incident solar radiation fluxes, atmospheric thermal emission, wind driven heat exchanges, heat dissipation into the soil, surface properties, and heat fluxes associated to the rover influence. The analysis helps understand the type of possible thermodynamic interactions occurring between the lower atmosphere and the soil.

  9. Abrupt changes, multidecadal variability and long-term trends in sea surface temperature and sea level datasets within the southeastern Bay of Biscay

    NASA Astrophysics Data System (ADS)

    González, Manuel; Fontán, Almudena; Esnaola, Ganix; Collins, Michael

    2013-01-01

    Multidecadal variability and long-term trends of Sea Surface Temperature (SST) and Sea Level (SL) datasets for the southeastern Bay of Biscay have been examined. The SST dataset (Aquarium of San Sebastián), measured on a nearly daily basis, extends from 1947 to 2010. The daily SL data utilised are those from Santander (IEO tide gauge network) and from St. Jean de Luz (SHOM), spanning the periods 1943-2004 and 1964-1997, respectively. This paper presents an approach for the extraction of multidecadal variability and long-term trends. First of all, the KZA (Kolmogorov-Zurbenko Adaptive) filter was used to detect possible discontinuities in time-series. Subsequently, the seasonal and multidecadal variability was identified by spectral analysis and further quantified by least squares fitting. Finally, prior to the trend determination, the long-term natural variability was removed. The results revealed significant contribution of the annual component to the SST and SL, with a weaker contribution of the semiannual signal. The sea level air pressure and long-term tides also contributed to the SL variability. The estimated trends were less than those obtained by other authors. The analysis revealed no trend in the SST and the Jean de Luz SL series, whilst an increasing trend was detected for the Santander SL dataset.

  10. Spatial Patterns of Variability in Antarctic Surface Temperature: Connections to the Southern Hemisphere Annular Mode and the Southern Oscillation

    NASA Technical Reports Server (NTRS)

    Kwok, Ron; Comiso, Josefino C.; Koblinsky, Chester J. (Technical Monitor)

    2002-01-01

    The 17-year (1982-1998) trend in surface temperature shows a general cooling over the Antarctic continent, warming of the sea ice zone, with moderate changes over the oceans. Warming of the peripheral seas is associated with negative trends in the regional sea ice extent. Effects of the Southern Hemisphere Annular Mode (SAM) and the extrapolar Southern Oscillation (SO) on surface temperature are quantified through regression analysis. Positive polarities of the SAM are associated with cold anomalies over most of Antarctica, with the most notable exception of the Antarctic Peninsula. Positive temperature anomalies and ice edge retreat in the Pacific sector are associated with El Nino episodes. Over the past two decades, the drift towards high polarity in the SAM and negative polarity in the SO indices couple to produce a spatial pattern with warmer temperatures in the Antarctic Peninsula and peripheral seas, and cooler temperatures over much of East Antarctica.

  11. Evaluation of the long-term variability of seawater salinity and temperature in response to natural and anthropogenic stressors in the Arabian Gulf.

    PubMed

    Elhakeem, Abubaker; Elshorbagy, Walid

    2013-11-15

    Evaluating the long-term variability of the seawater salinity and temperature due to climate change is a limiting economical and operational factor in planning the design of new and expansion of existing desalination plants. This need is amplified in the Arabian Gulf due to the natural arid climate and anthropological stresses related to energy exploration and ongoing major developments. The lack of data in this region further adds additional dimension to the problem. The present work represents a systematic innovative approach to evaluate the anticipated long-term changes in the seawater salinity and temperature under the stresses of projected climate change and massive industrial effluents using statistical correlation and hydrodynamic simulation. The proposed approach employs the direct relation between the net freshwater losses (evaporation) entrenched with the investigated stressors and the mean sea salinity and sea temperature variation of an inverse estuary to formulate the statistical correlation and the hydrodynamic simulation conditions. PMID:24055462

  12. Linkage isomerism of carbonyl coordination complexes formed upon CO adsorption on the zeolite Li-ZSM-5: variable-temperature FTIR studies

    NASA Astrophysics Data System (ADS)

    Otero Areán, C.; Rodríguez Delgado, M.; Manoilova, O. V.; Turnes Palomino, G.; Tsyganenko, A. A.; Garrone, E.

    2002-08-01

    Carbon monoxide adsorbed at a low-temperature on the zeolite Li-ZSM-5 forms Li +⋯CO and Li +⋯(CO) 2 species characterized by C-O stretching bands at 2195 and 2187 cm-1, respectively. These C-bonded carbonyls are in a temperature-dependent equilibrium with Li +⋯OC and CO⋯Li +⋯CO species having O-bonded CO. By means of variable-temperature FTIR spectroscopy, the enthalpy change involved in the corresponding isomerization process was found to be ?H°=7.8 kJ mol-1 for the monocarbonyl and ?H°=5.1 kJ mol-1 for the dicarbonyl. Therefore, although C-bonded species were always found to show a higher cation-CO interaction energy than O-bonded species, the difference is smaller in the case of dicarbonyls.

  13. Screening of inbred lines to develop a thermotolerant sunflower hybrid using the temperature induction response (TIR) technique: a novel approach by exploiting residual variability.

    PubMed

    Senthil-Kumar, M; Srikanthbabu, V; Mohan Raju, B; Ganeshkumar; Shivaprakash, N; Udayakumar, M

    2003-11-01

    Plants, when exposed to sub-lethal stress (induction stress), develop the ability to withstand severe temperatures and this phenomenon is often referred to as acquired thermotolerance. Earlier it was reported that induction stress alters gene expression and brings greater adaptation to heat stress and that the genetic variability in thermotolerance is only seen upon induction stress. Based on this concept, the temperature induction response (TIR) technique has been developed to identify thermotolerant lines. By following the TIR technique, sunflower hybrid KBSH-1 parents were screened for high temperature tolerance. Seedlings of parental lines including CMS 234 A, CMS 234 B and 6 D-1 showed considerable genetic variability for thermotolerance and it was attributed to the expression of existing residual variability for stress responses. Thus, the existing variability forms the basis for identifying thermotolerant lines. The identified parental inbred lines were selected and established in the field and crossed to get F1 hybrid seeds. The KBSH-1 hybrid developed from selected variants of parental lines was compared with the original KBSH-1 for thermotolerance. The selected KBSH-1 was more tolerant compared with the original hybrid both at the seedling as well as at the plant level. The physiological and molecular basis of thermotolerance was studied in the KBSH-1 original and the hybrid developed from selected variants of parental lines. The selected hybrid exhibited high tolerance to Menadione (naphthoquinone)-induced oxidative stress. Even the methyl viologen-induced oxidative stress damage was relatively less in the selected hybrid population. The selected hybrid also showed enhanced expression of the heat shock proteins HSP 90 and HSP 104 and also accumulated higher levels of the heat shock transcription factor HSFA. PMID:14565951

  14. Daily scale wintertime sea surface temperature and IPC-Navidad variability in the southern Bay of Biscay from 1981 to 2010

    NASA Astrophysics Data System (ADS)

    Esnaola, G.; Sáenz, J.; Zorita, E.; Fontán, A.; Valencia, V.; Lazure, P.

    2013-07-01

    The combination of remotely sensed gappy Sea surface temperature (SST) images with the missing data filling DINEOF (data interpolating empirical orthogonal functions) technique, followed by a principal component analysis of the reconstructed data, has been used to identify the time evolution and the daily scale variability of the wintertime surface signal of the Iberian Poleward Current (IPC), or Navidad, during the 1981-2010 period. An exhaustive comparison with the existing bibliography, and the vertical temperature and salinity profiles related to its extremes over the Bay of Biscay area, show that the obtained time series accurately reflect the IPC-Navidad variability. Once a time series for the evolution of the SST signal of the current over the last decades is well established, this time series is used to propose a physical mechanism in relation to the variability of the IPC-Navidad, involving both atmospheric and oceanic variables. According to the proposed mechanism, an atmospheric circulation anomaly observed in both the 500 hPa and the surface levels generates atmospheric surface level pressure, wind-stress and heat-flux anomalies. In turn, those surface level atmospheric anomalies induce mutually coherent SST and sea level anomalies over the North Atlantic area, and locally, in the Bay of Biscay area. These anomalies, both locally over the Bay of Biscay area and over the North Atlantic, are in agreement with several mechanisms that have separately been related to the variability of the IPC-Navidad, i.e. the south-westerly winds, the joint effect of baroclinicity and relief (JEBAR) effect, the topographic ? effect and a weakened North Atlantic gyre.

  15. Seasonal modes of dryness and wetness variability over Europe and their connections with large scale atmospheric circulation and global sea surface temperature

    NASA Astrophysics Data System (ADS)

    Ionita, Monica; Boroneant, Constanta; Chelcea, Silvia

    2015-04-01

    The relationship between the seasonal modes of interannual variability of a multiscalar drought index over Europe and the large-scale atmospheric circulation and sea surface temperature (SST) anomaly fields is investigated through statistical analysis of observed and reanalysis data. It is shown that the seasonal modes of dryness and wetness variability over Europe and their relationship with the large-scale atmospheric circulation and global sea surface temperature anomaly fields differ from one season to another. During winter, the dominant modes of dryness and wetness variability are influenced by the Arctic Oscillation (AO)/North Atlantic Oscillation (NAO), the Scandinavian pattern (SCA), the East Atlantic pattern (EA) and the East Atlantic/Western Russia (EAWR) pattern. The spring dryness/wetness modes are influenced mainly by the Arctic Oscillation (AO), Polar/Eurasian patterns (POL) and the Atlantic Multidecadal Oscillation (AMO) conditions. The phases (positive or negative) and the superposition of these large scale variability modes play a significant role in modulating the drought conditions over Europe. During summer, the atmospheric blocking is one of the main drivers of dryness and wetness conditions, while during autumn dryness/wetness conditions variability can be related to the NAO or with a wave train like pattern in the geopotential height at 850mb, which develops over the Atlantic Ocean and extends up to Siberia. It is also found that the response of the dryness and wetness conditions to global SST is more regional in summer, compared to the other seasons, when local processes may play a more important role.

  16. The Effect of Experimental Variables on Industrial X-Ray Micro-Computed Sensitivity

    NASA Technical Reports Server (NTRS)

    Roth, Don J.; Rauser, Richard W.

    2014-01-01

    A study was performed on the effect of experimental variables on radiographic sensitivity (image quality) in x-ray micro-computed tomography images for a high density thin wall metallic cylinder containing micro-EDM holes. Image quality was evaluated in terms of signal-to-noise ratio, flaw detectability, and feature sharpness. The variables included: day-to-day reproducibility, current, integration time, voltage, filtering, number of frame averages, number of projection views, beam width, effective object radius, binning, orientation of sample, acquisition angle range (180deg to 360deg), and directional versus transmission tube.

  17. Agricultural losses related to frost events: use of the 850 hPa level temperature as an explanatory variable of the damage cost

    NASA Astrophysics Data System (ADS)

    Papagiannaki, K.; Lagouvardos, K.; Kotroni, V.; Papagiannakis, G.

    2014-09-01

    The objective of this study is the analysis of damaging frost events in agriculture, by examining the relationship between the daily minimum temperature in the lower atmosphere (at an isobaric level of 850 hPa) and crop production losses. Furthermore, the study suggests a methodological approach for estimating agriculture risk due to frost events, with the aim of estimating the short-term probability and magnitude of frost-related financial losses for different levels of 850 hPa temperature. Compared with near-surface temperature forecasts, temperature forecasts at the level of 850 hPa are less influenced by varying weather conditions or by local topographical features; thus, they constitute a more consistent indicator of the forthcoming weather conditions. The analysis of the daily monetary compensations for insured crop losses caused by weather events in Greece shows that, during the period 1999-2011, frost caused more damage to crop production than any other meteorological phenomenon. Two regions of different geographical latitudes are examined further, to account for the differences in the temperature ranges developed within their ecological environment. Using a series of linear and logistic regressions, we found that minimum temperature (at an 850 hPa level), grouped into three categories according to its magnitude, and seasonality, are significant variables when trying to explain crop damage costs, as well as to predict and quantify the likelihood and magnitude of damaging frost events.

  18. Heat wave phenomenon in southern Slovakia: long-term changes and variability of daily maximum air temperature in Hurbanovo within the 1901-2009 period

    NASA Astrophysics Data System (ADS)

    Pecho, J.; Výber?i, D.; Jarošová, M.; Å¥Astný, P. Å.

    2010-09-01

    Analysis of long-term changes and temporal variability of heat waves incidence in the region of southern Slovakia within the 1901-2009 periods is a goal of the presented contribution. It is expected that climate change in terms of global warming would amplify temporal frequency and spatial extension of extreme heat wave incidence in region of central Europe in the next few decades. The frequency of occurrence and amplitude of heat waves may be impacted by changes in the temperature regime. Heat waves can cause severe thermal environmental stress leading to higher hospital admission rates, health complications, and increased mortality. These effects arise because of one or more meteorology-related factors such as higher effective temperatures, sunshine, more consecutive hot days and nights, stagnation, increased humidity, increased pollutant emissions, and accelerated photochemical smog and particulate formation. Heat waves bring about higher temperatures, increased solar heating of buildings, inhibited ventilation, and a larger number of consecutive warm days and nights. All of these effects increase the thermal loads on buildings, reduce their ability to cool down, and increase indoor temperatures. The paper is focused to analysis of long-term and inter-decadal temporal variability of heat waves occurrence at meteorological station Hurbanovo (time-series of daily maximum air temperature available from at least 1901). We can characterize the heat waves by its magnitude and duration, hence both of these characteristics need to be investigated together using sophisticated statistical methods developed particularly for the analysis of extreme hydrological events. We investigated particular heat wave periods either from the severity point of view using HWI index. In the paper we also present the results of statistical analysis of daily maximum air temperature within 1901-2009 period. Apart from these investigation efforts we also focused on synoptic causes of heat wave incidence in connection with macro scale circulation patterns in central European region.

  19. Terrestrial carbon sink observed from space: variation of growth rates and seasonal cycle amplitudes in response to interannual surface temperature variability

    NASA Astrophysics Data System (ADS)

    Schneising, O.; Reuter, M.; Buchwitz, M.; Heymann, J.; Bovensmann, H.; Burrows, J. P.

    2013-08-01

    The terrestrial biosphere is currently acting as a net carbon sink on the global scale exhibiting significant interannual variability in strength. To reliably predict the future strength of the land sink and its role in atmospheric CO2 growth the underlying processes and their response to a changing climate need to be well understood. In particular, better knowledge of the impact of key climate variables like temperature or precipitation on the biospheric carbon reservoir is essential. It is demonstrated using nearly a decade of SCIAMACHY nadir measurements that years with higher temperatures during the growing season can be robustly associated with larger growth rates in atmospheric CO2 and smaller seasonal cycle amplitudes for northern mid-latitudes. We find linear relationships between warming and CO2 growth as well as seasonal cycle amplitude at the 98% significance level. This suggests that the terrestrial carbon sink is less efficient at higher temperatures, which might lead to future sink saturation via a positive carbon-climate feedback. Quantitatively, the covariation between the annual CO2 growth rates derived from SCIAMACHY data and warm season surface temperature anomaly amounts to 1.25±0.32 ppm yr-1 K-1 for the Northern Hemisphere where the bulk of the terrestrial carbon sink is located. In comparison, the relation is less pronounced in the Southern Hemisphere. The covariation of the seasonal cycle amplitudes derived from satellite and temperature anomaly is -1.30±0.31 ppm K-1 for the north temperate zone. These estimates are consistent with those from the CarbonTracker data assimilated CO2 data product indicating that the temperature dependence of the model surface fluxes is realistic.

  20. Calculation of the temperature fields in a combined-heating furnace with a variable temperature of the wall and nonuniform gas distribution

    Microsoft Academic Search

    A. S. Kukarkin; B. I. Babanin; B. I. Kitaev; I. A. Kochkina; V. V. Lugovkin

    1982-01-01

    A solution is given to the problem of countercurrent exchange of a layer of lump material with a gas taking into account the transverse thermal conductivity of the layer. The boundary conditions of the first type are given by a linear distribution with respect to height of the temperature of the material present at the surface of the walls of

  1. Analysis of Climate Change Impact on Extreme Precipitation and Temperature Variability over the Willamette River Basin Using Dynamically Downscaled Climate Scenarios

    NASA Astrophysics Data System (ADS)

    Halmstad, A.; Najafi, M.; Moradkhani, H.

    2011-12-01

    Understanding the historic occurrence of extreme precipitation and temperature events, as well as future variations in the face of climate change, represents a core research area for climate scientists and water resource engineers. Recent advancements in regional climate modeling provide resources for investigating the occurrence of such extreme events. This study evaluates temperature and precipitation data from multiple Regional Climate Models (RCMs), driven by multiple General Circulation Models (GCMs) as well as a reanalysis dataset (NCEP Reanalysis II). All of these climate scenario datasets were produced as part of the North American Regional Climate Change Assessment Program (NARCCAP). A comparison between observed extreme temperature and precipitation events and RCM modeled historical conditions over Oregon's Willamette River basin was performed. Datasets representing future climate scenarios were then compared to historical data, thus providing an estimate of the variability in extreme event frequency and intensity within the basin. Simulated future precipitation and temperature datasets were initially bias corrected using two methods, the delta change approach and quantile mapping. Parametric analysis of the precipitation extremes were performed based on the Generalized Extreme Value (GEV) distribution for each grid-point and the results were compared to the ones from Regional Frequency Analysis (RFA) which pools the data from different locations. The analysis includes a procedure for estimating the parameters of the GEV distribution and also estimating the spatial distribution of climate variables at different recurrence intervals. The Added Value Index (AVI) metric was calculated for the datasets in order to provide a quantitative measure of the improvement of RCM simulations over those provided by GCMs alone. The results demonstrate the value of multi-model ensemble analysis due to RCM and GCM variability and the importance of bias correction on RCM datasets when investigating watershed scale phenomena.

  2. Effects of color temperatures (kelvin) of led bulbs on blood physiological variables of broilers grown to heavy weights

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Light-emitting diode (LED) lighting is being used in the poultry industry to reduce energy usage in broiler production facilities. However, limited data are available comparing efficacy of different spectral distribution of LED bulbs on blood physiological variables of broilers grown to heavy weight...

  3. Effects of Variable Aspect-Ratio Inclusions on the Electrical Impedance of an Alumina Zirconia Composite at Intermediate Temperatures

    NASA Technical Reports Server (NTRS)

    Goldsby, Jon C.

    2010-01-01

    A series of alumina-yttria-stabilized zirconia composites containing either a high aspect ratio (5 and 30 mol%) hexagonal platelet alumina or an alumina low aspect ratio (5 and 30 mol%) spherical particulate was used to determine the effect of the aspect ratio on the temperature-dependent impedance of the composite material. The highest impedance across the temperature range of 373 to 1073 K is attributed to the grain boundary of the hexagonal platelet second phase in this alumina zirconia composite.

  4. A climatological analysis of the seasonal variability of surface temperature and circulation over the Canary current upwelling system.

    NASA Astrophysics Data System (ADS)

    Faye, Saliou; Lazar, Alban; Sow, Bamol; Gaye, Amadou

    2015-04-01

    The seasonal climatological budget of the mixed layer temperature of the Canary Current upwelling system (CCUS) is described and analyzed using an eddy permitting numerical simulation of the Tropical Atlantic, validated against observed surface temperature, winds and currents. During the so-called cooling period from November to May, the maximum temperature decrease is observed over an area extending meridionnaly along Mauritania and Senegal and over about 1-2° of longitude from the coast .It is driven mainly by vertical turbulent mixing, due to the season strengthening of Ekman pumping and vertical shear of horizontal currents, and by horizontal advection of northern waters.. Farther offshore, except near the Cap Verde islands away from the direct influence of coastal upwelling, the SST drop is mainly governed by air-sea fluxes,. During the so-called warming season from June to October, the temperature increase is overall driven by air-sea heat fluxes, except south of about 10-12°N. There, horizontal advection and vertical turbulent mixing control the temperature due to the influence of, respectively, the North Equatorial Counter-Current and temperature inversions just below the MLD. A more detailed analysis is proposed along the coastal region

  5. Calculation of the temperature fields in a combined-heating furnace with a variable temperature of the wall and nonuniform gas distribution

    SciTech Connect

    Kukarkin, A.S.; Babanin, B.I.; Kitaev, B.I.; Kochkina, I.A.; Lugovkin, V.V.

    1982-01-01

    A solution is given to the problem of countercurrent exchange of a layer of lump material with a gas taking into account the transverse thermal conductivity of the layer. The boundary conditions of the first type are given by a linear distribution with respect to height of the temperature of the material present at the surface of the walls of the shaft. Making use of this solution, calculations have been performed of the temperature fields in a combined-heating furnace for the production of shaped coke. The gas distribution in the layer was taken both as equilibrium over the horizontal cross-section and also as nonequilibrium taking the wall effect into account. The calculations have shown that nonuniform gas distribution adversely affects the heating of the layer in the cnetral zone and leads to incomplete coking in this part of the furnace.

  6. Evidence of multidecadal climate variability and the Atlantic Multidecadal Oscillation from a Gulf of Mexico sea-surface temperature-proxy record

    USGS Publications Warehouse

    Poore, R.Z.; DeLong, K.L.; Richey, J.N.; Quinn, T.M.

    2009-01-01

    A comparison of a Mg/Ca-based sea-surface temperature (SST)-anomaly record from the northern Gulf of Mexico, a calculated index of variability in observed North Atlantic SST known as the Atlantic Multidecadal Oscillation (AMO), and a tree-ring reconstruction of the AMO contain similar patterns of variation over the last 110 years. Thus, the multidecadal variability observed in the instrumental record is present in the tree-ring and Mg/Ca proxy data. Frequency analysis of the Gulf of Mexico SST record and the tree-ring AMO reconstruction from 1550 to 1990 found similar multidecadal-scale periodicities (???30-60 years). This multidecadal periodicity is about half the observed (60-80 years) variability identified in the AMO for the 20th century. The historical records of hurricane landfalls reveal increased landfalls in the Gulf Coast region during time intervals when the AMO index is positive (warmer SST), and decreased landfalls when the AMO index is negative (cooler SST). Thus, we conclude that alternating intervals of high and low hurricane landfall occurrences may continue on multidecadal timescales along the northern Gulf Coast. However, given the short length of the instrumental record, the actual frequency and stability of the AMO are uncertain, and additional AMO proxy records are needed to establish the character of multidecadal-scale SST variability in the North Atlantic. ?? 2009 US Government.

  7. Inter-Annual Variability of Currents, Temperature and Salinity during 1998-2012 in a High-Resolution Ocean Model of the Western Indian Ocean

    NASA Astrophysics Data System (ADS)

    Jensen, T. G.; Ko, D. S.; Wijesekera, H. W.

    2014-12-01

    A simulation of the 3-dimensional ocean temperature, salinity and currents of from 1998 through 2012 was done using the Navy Coastal Ocean Model (NCOM) with a 6-km resolution and 40 vertical sigma-z levels. The forcing is 3-hourly atmospheric output from the Navy's Operational Global Prediction System (NOGAPS). The boundary conditions are provided by the 1/8o Global NCOM model. In addition, 8 semi-diurnal and diurnal tidal components and monthly climatological discharges of 37 rivers are included. The model assimilates satellite altimeter data, AVHRR SST and synthetic temperature and salinity profiles from the Modular Ocean Data Assimilation System (MODAS). The model output is filtered to remove tides and saved as daily averages. From out analysis we find large inter-annual variability in the strength of the South Equatorial Counter Current and in the subsurface temperature cold anomaly associated with Seyshelles-Chagos thermocline ridge. The cold anomaly was significantly reduced in 2007 during which had a rare co-occurrence of La Nina and positive Indian Ocean Dipole conditions. Year to year variability in the equatorial currents affects the Somali Current and the time of development and strength of the Great Whirl during the southwest monsoon.

  8. Community change and evidence for variable warm-water temperature adaptation of corals in Northern Male Atoll, Maldives.

    PubMed

    McClanahan, T R; Muthiga, N A

    2014-03-15

    This study provides a descriptive analysis of the North Male, Maldives seven years after the 1998 bleaching disturbance to determine the state of the coral community composition, the recruitment community, evidence for recovery, and adaptation to thermal stress. Overall, hard coral cover recovered at a rate commonly reported in the literature but with high spatial variability and shifts in taxonomic composition. Massive Porites, Pavona, Synarea, and Goniopora were unusually common in both the recruit and adult communities. Coral recruitment was low and some coral taxa, namely Tubipora, Seriatopora, and Stylophora, were rarer than expected. A study of the bleaching response to a thermal anomaly in 2005 indicated that some taxa, including Leptoria, Platygyra, Favites, Fungia, Hydnophora, and Galaxea astreata, bleached as predicted while others, including Acropora, Pocillopora, branching Porites, Montipora, Stylophora, and Alveopora, bleached less than predicted. This indicates variable-adaptation potentials among the taxa and considerable potential for ecological reorganization of the coral community. PMID:24486038

  9. The Definition of British Water Beetle Species Pools (Coleoptera) and their Relationship to Altitude, Temperature, Precipitation and Land Cover Variables

    Microsoft Academic Search

    M. D. Eyre; G. N. Foster; M. L. Luff; S. P. Rushton

    2006-01-01

    Pooled water beetle species lists from 1826 British national grid 10-km squares were analysed using multivariate ordination\\u000a and classification methods. The relationships of pool groups to the climate, altitude and land cover variables were assessed\\u000a using constrained and partial ordinations. Ordination of the species pool data indicated a major trend between squares in\\u000a the north-west of Scotland and those in

  10. Sea-level and deep-sea-temperature variability over the past 5.3 million years.

    PubMed

    Rohling, E J; Foster, G L; Grant, K M; Marino, G; Roberts, A P; Tamisiea, M E; Williams, F

    2014-04-24

    Ice volume (and hence sea level) and deep-sea temperature are key measures of global climate change. Sea level has been documented using several independent methods over the past 0.5 million years (Myr). Older periods, however, lack such independent validation; all existing records are related to deep-sea oxygen isotope (?(18)O) data that are influenced by processes unrelated to sea level. For deep-sea temperature, only one continuous high-resolution (Mg/Ca-based) record exists, with related sea-level estimates, spanning the past 1.5 Myr. Here we present a novel sea-level reconstruction, with associated estimates of deep-sea temperature, which independently validates the previous 0-1.5 Myr reconstruction and extends it back to 5.3 Myr ago. We find that deep-sea temperature and sea level generally decreased through time, but distinctly out of synchrony, which is remarkable given the importance of ice-albedo feedbacks on the radiative forcing of climate. In particular, we observe a large temporal offset during the onset of Plio-Pleistocene ice ages, between a marked cooling step at 2.73 Myr ago and the first major glaciation at 2.15 Myr ago. Last, we tentatively infer that ice sheets may have grown largest during glacials with more modest reductions in deep-sea temperature. PMID:24739960

  11. Effect of heat shock and recovery temperature on variability of single cell lag time of Cronobacter turicensis.

    PubMed

    Xu, Y Zh; Métris, A; Stasinopoulos, D M; Forsythe, S J; Sutherland, J P

    2015-02-01

    The effect of heat stress and subsequent recovery temperature on the individual cellular lag of Cronobacter turicensis was analysed using optical density measurements. Low numbers of cells were obtained through serial dilution and the time to reach an optical density of 0.035 was determined. Assuming the lag of a single cell follows a shifted Gamma distribution with a fixed shape parameter, the effect of recovery temperature on the individual lag of untreated and sublethally heat treated cells of Cr. turicensis were modelled. It was found that the shift parameter (Tshift) increased asymptotically as the temperature decreased while the logarithm of the scale parameter (?) decreased linearly with recovery temperature. To test the validity of the model in food, growth of low numbers of untreated and heat treated Cr. turicensis in artificially contaminated infant first milk was measured experimentally and compared with predictions obtained by Monte Carlo simulations. Although the model for untreated cells slightly underestimated the actual growth in first milk at low temperatures, the model for heat treated cells was in agreement with the data derived from the challenge tests and provides a basis for reliable quantitative microbiological risk assessments for Cronobacter spp. in infant milk. PMID:25500385

  12. Isoprene and monoterpene emission rate variability: Observations with Eucalyptus and emission rate algorithm development

    NASA Astrophysics Data System (ADS)

    Guenther, Alex B.; Monson, Russell K.; Fall, Ray

    1991-06-01

    Variability in the emission rates of isoprene and monoterpenes from individual leaves of Eucalyptus globulus was investigated with a laboratory gas exchange system and an environmental control leaf cuvette. For individual leaves, with constant environmental conditions, short-term (1 hour) fluctuations in isoprene emission rates were less than 3% while day-to-day fluctuations averaged 14%. Leaf-to-leaf variations were much larger (62%). Fluctuations with time and leaf-to-leaf variability in CO2 assimilation rates were of the same order as isoprene, while monoterpene variations were higher. Leaf age was identified as one of the factors contributing to leaf-to-leaf variability in CO2 assimilation and isoprene and monoterpene emission rates. Monoterpene emission rates were not influenced by light intensity or CO2 mixing ratio. The observed temperature dependence was the same for ?-pinene and 1,8-cineole (an oxygenated monoterpene) and is similar to the temperature dependence of monoterpene emission rates reported by other investigators. Isoprene emissions were slightly dependent on humidity (1-3% increase in emission per 10% increase in relative humidity) and responded only to very low (<100 ppm) or very high (>600 ppm) CO2 mixing ratios. Isoprene emission was associated with the abaxial leaf side, which contains stomatal pores, while monoterpenes were emitted primarily from the adaxial side, which lacks stomatal pores. The temperature and light dependence of isoprene emission closely resembles relationships observed for electron transport in plant chloroplasts. For this reason, we have used a mechanistic electron transport model as the basis for an empirical isoprene emission rate model. The emission rate variation predicted by this model was within 10% of observed values for 62% of the 255 observations at light-saturated conditions and temperatures between 23° and 33°C. The entire data base includes over 600 observations at leaf temperatures ranging between 12° and 50°C and light intensities between 0 and 2000 ?mol m-2 s-1. Nearly two thirds of the emission rates predicted for the entire data base were within a factor of 1.25, and 89% were within a factor of 2. The algorithms developed in this study provide a solid physiological basis for future efforts to model the biogenic flux of isoprene and monoterpenes into the atmosphere.

  13. Uncertainties in Seawater Paleothermometry Deriving From Intra- and Inter-Test Mg/Ca Variability in Globigerinoides ruber. How Accurate are we on Reconstructing Palaeocean Temperatures?

    NASA Astrophysics Data System (ADS)

    Sadekov, A. Y.; Eggins, S. M.; Deckker, P. D.

    2006-12-01

    Globigerinoides ruber is a widely studied planktonic foraminifera, it being a key species used for palaeoceanographic reconstructions based on bulk calcite Mg/Ca and ^18O geochemistry. However, recent microanalytical studies show significant variation of Mg/Ca values within individual G.ruber tests that can be linked to a strong and variable biological influence upon the incorporation of Mg into test calcite. We have employed LA-ICPMS (laser ablation inductively coupled plasma mass spectrometer) to assess the impact of inter- and intra-test Mg/Ca variability on seawater paleothermometry using the Mg/Ca composition of G.ruber. Between 20 and 35 individual G.ruber tests were analysed from each of eight core-top samples that span a large latitudinal (equator to 35ºS) and sea surface temperature (18.5-29.2ºC) range in the eastern Indian Ocean. Despite the large Mg/Ca variability documented among individual foraminifera that comprise each sediment core-top population of G. ruber, the mean Mg/Ca value obtained for the core-tope samples shows a strong exponential correlation with annual SST, consistent with calibrations obtained previously by studies that have employed conventional bulk analysis methods. While our results confirm the robustness of the relationship between G. ruber Mg/Ca composition and SST and its use as a paleo-seawater thermometer, they provide new insights into the size and variation of error estimates associated with the analysis of a mean Mg/Ca composition for a sample comprising multiple foraminifer tests. In particular, we find that the extent of intra-rest Mg/Ca variability is sample site specific, and varies significantly depending on several factors that include differences in the proportion of G. ruber morphotypes present and the seasonal temperature variation, as well as the effects sediment rate and bioturbation.

  14. Evaluation of RegCM4 driven by CAM4 over Southern Africa: mean climatology, interannual variability and daily extremes of wet season temperature and precipitation

    NASA Astrophysics Data System (ADS)

    Diallo, Ismaïla; Giorgi, Filippo; Sukumaran, Sandeep; Stordal, Frode; Giuliani, Graziano

    2014-09-01

    We present an analysis of a present-day climate simulation (1990-2009) for the Southern Africa region with the RegCM4 regional climate model (RCM, dx = 25 km ~0.22°) driven by the Community Atmospheric Model version 4 (CAM4) global climate model (GCM, dx = 1°). We assess the capability of the models to simulate the observed climate of the region with emphasis on precipitation, 2-m mean, minimum, and maximum temperature and large-scale circulation. The analysis focuses on seasonal climatologies, annual cycles, interannual variability, and extreme events. In addition to evaluating the performance of the models, we also attempt to assess the added value of the regional model compared to the driving one. With a few exceptions, we find that the models reproduce reasonably well the mean spatial patterns of 2-m temperature and precipitation, along with the associated seasonal cycle and interannual variability over selected sub-regions. Extreme indices of temperature and precipitation are also reasonably well reproduced. However, the RegCM4 substantially improves the simulation of daily precipitation frequency and duration of dry and wet events compared to CAM4 due to its higher resolution. The global and regional models exhibit quite different patterns of bias, an indication of the importance of internal variability and process representation for the simulation of surface climate. Given the good performance shown by the nested CAM4-RegCM4 system, we plan to use these models to generate an ensemble of projections for use in impact assessment studies for the region.

  15. IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY, VOL. 17, NO. 2, JUNE 2007 3179 Variable Temperature Total AC Loss and Stability

    E-print Network

    of high temperature superconductors (HTS) are looking more promising with the advances in commercial engineering data [3]­[14]. The topic of quench sta- bility and normal zone propagation is also attracting attention [15], [16]. Reliable data on ac losses and quench stability are essential in designing cryogenic

  16. The potential impacts of climate variability and change on temperature-related morbidity and mortality in the United States.

    PubMed Central

    McGeehin, M A; Mirabelli, M

    2001-01-01

    Heat and heat waves are projected to increase in severity and frequency with increasing global mean temperatures. Studies in urban areas show an association between increases in mortality and increases in heat, measured by maximum or minimum temperature, heat index, and sometimes, other weather conditions. Health effects associated with exposure to extreme and prolonged heat appear to be related to environmental temperatures above those to which the population is accustomed. Models of weather-mortality relationships indicate that populations in northeastern and midwestern U.S. cities are likely to experience the greatest number of illnesses and deaths in response to changes in summer temperature. Physiologic and behavioral adaptations may reduce morbidity and mortality. Within heat-sensitive regions, urban populations are the most vulnerable to adverse heat-related health outcomes. The elderly, young children, the poor, and people who are bedridden or are on certain medications are at particular risk. Heat-related illnesses and deaths are largely preventable through behavioral adaptations, including the use of air conditioning and increased fluid intake. Overall death rates are higher in winter than in summer, and it is possible that milder winters could reduce deaths in winter months. However, the relationship between winter weather and mortality is difficult to interpret. Other adaptation measures include heat emergency plans, warning systems, and illness management plans. Research is needed to identify critical weather parameters, the associations between heat and nonfatal illnesses, the evaluation of implemented heat response plans, and the effectiveness of urban design in reducing heat retention. PMID:11359685

  17. Effects of temperature and precipitation variability on the risk of violence in sub-Saharan Africa, 1980–2012

    PubMed Central

    O’Loughlin, John; Linke, Andrew M.; Witmer, Frank D. W.

    2014-01-01

    Ongoing debates in the academic community and in the public policy arena continue without clear resolution about the significance of global climate change for the risk of increased conflict. Sub-Saharan Africa is generally agreed to be the region most vulnerable to such climate impacts. Using a large database of conflict events and detailed climatological data covering the period 1980–2012, we apply a multilevel modeling technique that allows for a more nuanced understanding of a climate–conflict link than has been seen heretofore. In the aggregate, high temperature extremes are associated with more conflict; however, different types of conflict and different subregions do not show consistent relationship with temperature deviations. Precipitation deviations, both high and low, are generally not significant. The location and timing of violence are influenced less by climate anomalies (temperature or precipitation variations from normal) than by key political, economic, and geographic factors. We find important distinctions in the relationship between temperature extremes and conflict by using multiple methods of analysis and by exploiting our time-series cross-sectional dataset for disaggregated analyses. PMID:25385621

  18. Use of a variable exposure photographic pyrometer to measure surface temperatures on a hemispherical-face model

    NASA Technical Reports Server (NTRS)

    Kantsios, A. G.; Henley, W. C., Jr.; Snow, W. L.

    1982-01-01

    The use of a photographic pyrometer for nonintrusive measurement of high temperature surfaces in a wind tunnel test is described. The advantages of the pyrometer for measuring surfaces whose unique shape makes use of thermocouples difficult are pointed out. The use of computer operated densitometers or optical processors for the data reduction is recommended.

  19. Intraseasonal Variability of Surface Fluxes and Sea Surface Temperature in the Tropical Western Pacific and Indian Oceans

    Microsoft Academic Search

    Toshiaki Shinoda; Harry H. Hendon; John Glick

    1998-01-01

    Composites of sea surface temperature (SST), surface heat, momentum, and freshwater flux anomalies associated with intraseasonal oscillations of convection are developed for the warm pool of the western Pacific and Indian Oceans during 1986-93. The composites are based on empirical orthogonal function analysis of intraseasonally filtered outgoing longwave radiation (OLR), which efficiently extracts the Madden-Julian oscillation (MJO) in convection. Surface

  20. Genetic Variability of Flight Metabolism in DROSOPHILA MELANOGASTER . III. Effects of Gpdh Allozymes and Environmental Temperature on Power Output

    PubMed Central

    Barnes, Phillip T.; Laurie-Ahlberg, Cathy C.

    1986-01-01

    The effect of allozyme variation at the sn-glycerol-3-phosphate dehydrogenase (Gpdh) locus on variation in the mechanical power output of the flight muscles of Drosophila melanogaster was investigated. The influence of different rearing and flight temperatures and of their interactions with the Gpdh allozymic genotypes (allotypes) on flight ability also were analyzed. Populations from three continents were used, and Gpdh allotypes were generated from crosses between randomly paired isofemale lines made autozygous for each of the two alleles by inbreeding. Measurements made during tethered flight, together with wing morphology, were used to estimate power output using both Weis-Fogh's and Ellington's formulas.—Analyses of variance (ANOVA) indicated significant main effects for both environmental components (rearing and flight temperatures) but for only one of the three genetic components (genetic backgrounds within continent); Gpdh allotypes and populations (continent of origin) were not significant. The interaction between rearing and flight temperature was highly significant, indicating some physiological adaptation. The effect of Gpdh allozymes depended on both rearing and flight temperature and was either significant or marginally so, depending on which set of formulas was used. In either case, the S/S allotype showed a 2–4% greater power output than the F/F allotype at low temperature for both interactions. In addition, the S/S allotype showed significantly greater power output than the F/F allotype among flies raised at 15° and flown at 15°, whereas the reverse was true for flies raised at 30° and flown at 30°. Significant differences among the three allotypes for GPDH activity level were found in general, with S/S having the highest, F/S intermediate and F/F the lowest activity, and an inverse relationship existed between rearing temperature and activity.—The temperature effects on power output are consistent with the geographical and seasonal variation observed at the Gpdh locus in nature. In general, the results show that Gpdh can be considered a minor polygene affecting quantitative variation in the power output during flight and that genotype-by-environment interaction is an important component of that effect. PMID:3079721

  1. Complexation of Lactate with Nd(III) and Eu(III) at Variable Temperatures: Studies by Potentiometry, Microcalorimetry, Optical Absorption and Luminescence Spectroscopy

    SciTech Connect

    Tian, Guoxin; Martin, Leigh R.; Rao, Linfeng

    2010-10-01

    Complexation of neodymium(III) and europium(III) with lactate was studied at variable temperatures by potentiometry, absorption spectrophotometry, luminescence spectroscopy and microcalorimetry. Stability constants of three successive lactate complexes (ML{sup 2+}, ML{sup 2+} and ML{sub 3}(aq), where M stands for Nd and Eu, and L stands for lactate) at 10, 25, 40, 55 and 70 C were determined. The enthalpies of complexation at 25 C were determined by microcalorimetry. Thermodynamic data show that the complexation of trivalent lanthanides (Nd{sup 3+} and Eu{sup 3+}) with lactate is exothermic, and the complexation becomes weaker at higher temperatures. Results from optical absorption and luminescence spectroscopy suggest that the complexes are inner-sphere chelate complexes in which the protonated {alpha}-hydroxyl group of lactate participates in the complexation.

  2. Variable-temperature X-ray powder diffraction analysis of the crystal transformation of the pharmaceutically preferred polymorph C of mebendazole.

    PubMed

    de Villiers, Melgardt M; Terblanche, Rudolf J; Liebenberg, Wilna; Swanepoel, Erna; Dekker, Theo G; Song, Mingna

    2005-07-01

    Mebendazole is a common benzimidazole anthelmintic that is water insoluble. It is reported to exist in three different polymorphic forms in the solid state, i.e. polymorph A, B and C. Form C is the pharmaceutically preferred form because of its increased aqueous solubility. This paper deals with the use of variable-temperature X-ray powder analysis (VTXRPD) to study the transformation of Form C. Results showed that Form C was stable and transformed to the more stable polymorph A at high temperature (>180 degrees C). This transformation is a first-order process with activation energy of 238 +/- 16 kJ/mole. Further studies showed that compression did not cause any significant changes in the crystal structure of polymorph C. PMID:15925244

  3. 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.

  4. Effect of variable substrate temperature for SrTiO3 thin films using pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Wan, Xiaojing; Wang, Li; Su, Xueqiong; Chen, Jiangbo; Kong, Le

    2010-10-01

    In this paper, the high temperature solid state reaction method was applied to the preparation of SrTiO3 ceramic target. The phase of the target has been researched in experiment by X-ray diffraction (XRD). We found that solid state reaction has achieved completely. Then SrTiO3 thin films on MgO (100) substrate were manufactured by PLD using the triple-frequency harmonics of pulsed laser Nd: YAG. The thickness of the SrTiO3 thin films was measured using a stylus profiler. Their microstructure and surface morphology were analyzed using X-ray diffraction (XRD) and atomic force microscopy (AFM). Their optical character was characterized using optical transmission spectrum. Additionally, X-ray photoelectron spectroscopy (XPS) spectra were used to characterize the surface chemical composition of the SrTiO3 thin film. In accordance with the above text result, the relation between the substrate temperature and the SrTiO3 thin films' the structure and character was analyzed and discussed. With increasing temperature of the substrate, film grain size gradually increased and then smaller. The optimized substrate temperature was found to be 700 °C at which the STO films' structure could uniformly dense. The STO films present a low optical absorption in the 400{1000nm wavelength range, and the substrate temperature is not the main reason for the impact of the optical absorption. The optical band gap energy was found to be about 3.5 { 4.0eV for the STO thin film. The valences of the three elements (Sr, Ti, and O) in the STO film prepared by PLD are 2+, 4+ and 2-, respectively.

  5. Effect of Temperature and Other Variables on the Optimum Formulation of Anionic Extended Surfactant–Alkane–Brine Systems

    Microsoft Academic Search

    Josmary Velásquez; Cesar Scorzza; Francia Vejar; Ana M. Forgiarini; Raquel E. Antón; Jean-Louis Salager

    2010-01-01

    Anionic extended surfactants of the alkyl polypropylene oxide sulfate type are found to obey the linear correlation lnS = k ACN for optimum formulation (three-phase behavior) of ionic surfactant–oil–water systems, with a k value essentially the same as for n-alkyl sulfates. The addition of n-pentanol produces a shift in optimum formulation without significant change in k. An increase in temperature is found

  6. Variable temperature EPR study for confirming dynamic Jahn–Teller distortion in Cu(II) doped zinc ammonium phosphate hexahydrate

    Microsoft Academic Search

    E. Poonguzhali; R. Srinivasan; R. Venkatesan; R. V. S. S. N. Ravikumar; P. Sambasiva Rao

    2003-01-01

    Single crystal EPR rotations done about the three mutually orthogonal axes at 300 and 143K for copper(II) doped zinc ammonium phosphate hexahydrate indicate that the spin Hamiltonian parameters (g and A) are highly temperature dependent, whereas their direction cosines are not to that extent. Powder spectra of the sample recorded from 300 to 77K confirm dynamic Jahn–Teller distortion for Cu(II)

  7. Large-Scale Variability of Atmospheric Deep Convection in Relation to Sea Surface Temperature in the Tropics

    Microsoft Academic Search

    Chidong Zhang

    1993-01-01

    Empirical relationships between tropical sea surface temperature (SST) and atmospheric deep convection are examined. Large-scale features of tropical deep convection are estimated from two independent satellite datasets: monthly mean outgoing longwave radiation of 15 years and high-resolution pentad (5 day) fractional coverage of infrared radiation histograms of 5 years. Results based on the two datasets lead to the same conclusions.The

  8. Sea-surface temperature variability and deep water reorganisation in the subtropical North Atlantic during Isotope Stage 2–4

    Microsoft Academic Search

    Sveinung Hagen; Lloyd D Keigwin

    2002-01-01

    Two sediment cores from a high-accumulation sediment drift at ?3000-m water depth in the western North Atlantic are investigated in order to examine possible linkages between subtropical surface and bottom water properties, and global climate oscillations during the last glacial–interglacial cycle. Planktonic foraminiferal assemblages and the ?18O of Globigerinoides ruber both document large sea-surface temperature oscillations (3–4°C) that appear to

  9. Alkenones and hydrogen isotopic composition of n-alkanes as indicators of past temperature and hydrological variability from Lake Toyoni (Japan).

    NASA Astrophysics Data System (ADS)

    McColl, Jill; Seki, Osamu; Couto, Jillian; Bendle, James; Henderson, Andrew; Toney, Jaime

    2015-04-01

    A better understanding of decadal to centennial climate variability is vital to improve the accuracy of near future climate prediction. Hokkaido represents a region which has limited paleo-climate data and is sensitive to climate change. Throughout the instrumental period (last ~150-years), temperature and rainfall in Hokkaido, Japan show a link to the Pacific Decadal Oscillation (PDO) and the East Asian Summer Monsoon (EASM). However, conditions prior to the instrumental record are unknown and it is unclear if the PDO and EASM have always been the dominant drivers of climate in this region. A 250-cm long sediment core from Lake Toyoni, Hokkaido was retrieved to investigate lake temperature and hydrological changes over the past 1000-years using alkenone paleothermometry and the hydrogen isotope values of plant waxes, respectively. Here we present the first lacustrine alkenone record from Japan, including genetic analysis of the alkenone producer. C37 alkenone concentrations in surface sediments are 18?g C37 g?1 of dry sediment and the dominant alkenone is C37:4 . 18S rDNA analysis revealed the presence of a single alkenone producer in Lake Toyoni and thus a single calibration for reconstructing lake temperature based on alkenone unsaturation patterns. Temperature reconstructions over the past 1000 years suggest lake water changes of 8-19°C which is in line with water temperature changes observed in Lake Toyoni. Hydrologic variations inferred from the hydrogen isotopes of plant waxes suggest that the large fluctuations (~40‰) represent changes in temperature and source precipitation in this region. These results suggest that alkenones and the ?D(HPW) preserved in Lake Toyoni record regional climate changes over decadal timescales. These fluctuations will be discussed in relation to globally recognised climate events, specifically the Medieval Warm Period and the Little Ice Age

  10. Variable-Temperature In Situ X-ray Diffraction Study of the Thermodynamic Evolution of AgSbTe2 Thermoelectric Compound

    NASA Astrophysics Data System (ADS)

    Du, B.; Yan, Y.; Tang, X.

    2015-06-01

    Although AgSbTe2 compound has been intensively studied as a promising medium-temperature p-type thermoelectric (TE) material, its thermodynamic stability is still a controversial issue. We have prepared selenium-doped and pristine AgSbTe2 compounds from high-purity elements by a melt-quench-spark plasma sintering (Melt-SPS) or a melt spinning-SPS technique (MS-SPS). The influences of rapid solidification and selenium impurity on the thermodynamic evolution of AgSbTe2 TE compound have been studied by variable-temperature in situ x-ray diffraction over the temperature range from 25°C to 450°C. AgSbTe2 is a high-temperature metastable phase, and ultrahigh cooling rate in melt spinning is favorable to achieve phase-pure and homogeneous AgSbTe2 compound. The maximum possible short-time working temperature for AgSbTe2 TE compound is 250°C. Above 300°C, pristine AgSbTe2 is prone to slow decomposition to Sb2Te3, Ag5Te3, and ?-Ag2Te binary compounds, regardless of preparation route. The MS-SPS sample underwent a nearly reversible phase transition on cooling to room temperature, while the Melt-SPS sample decomposed irreversibly after measurement. Selenium-doped specimen showed robust thermodynamic stability below 300°C, and experienced distinct phase transition compared with pristine specimen above 330°C, evidencing a profound influence of selenium doping on the thermodynamic stability of AgSbTe2 thermoelectric compound.

  11. Design and Application of Variable Temperature Setup for Scanning Electron Microscopy in Gases and Liquids at Ambient Conditions.

    PubMed

    Al-Asadi, Ahmed S; Zhang, Jie; Li, Jianbo; Potyrailo, Radislav A; Kolmakov, Andrei

    2015-06-01

    Scanning electron microscopy (SEM) of nanoscale objects in dry and fully hydrated conditions at different temperatures is of critical importance in revealing details of their interactions with an ambient environment. Currently available WETSEM capsules are equipped with thin electron-transparent membranes and allow imaging of samples at atmospheric pressure, but do not provide temperature control over the sample. Here, we developed and tested a thermoelectric cooling/heating setup for WETSEM capsules to allow ambient pressure in situ SEM studies with a temperature range between -15 and 100°C in gaseous, liquid, and frozen conditions. The design of the setup also allows for correlation of the SEM with optical microscopy and spectroscopy. As a demonstration of the possibilities of the developed approach, we performed real-time in situ microscopy studies of water condensation on a surface of Morpho sulkowskyi butterfly wing scales. We observed that initial water nucleation takes place on top of the scale ridges. These results confirmed earlier discovery of a preexisting polarity gradient of the ridges of Morpho butterflies. Our developed thermoelectric cooling/heating setup for environmental capsules meets the diverse needs for in situ nanocharacterization in material science, catalysis, microelectronics, chemistry, and biology. PMID:26036327

  12. Column temperature as an active variable in the isocratic, normal-phase high-performance liquid chromatography separation of lipophilic metabolites of nonylphenol ethoxylates.

    PubMed

    Babay, Paola A; Gettar, Raquel T; Magallanes, Jorge F; Becquart, Elena T; Thiele, Björn; Batistoni, Daniel A

    2007-07-20

    Normal-phase separation of technical grade nonylphenol (t-NP, about 90% 4-nonylphenol), 4-nonylphenol mono-ethoxylate (4-NP1EO) and 4-nonylphenol di-ethoxylate (4-NP2EO) was assessed, with the inclusion of column temperature as an active variable. The compound 2,4,6-trimethylphenol was evaluated for use as internal standard. Isocratic elution with 2-propanol/hexanes mixtures from an amino-silica column and spectrometric UV detection at 277 nm were employed. Technical nonylphenol presented a significant contribution from unknown substances that eluted with retention times similar to that of 4-NP1EO. GC-MS analysis of the unknowns allowed to identify them as isomers of 2-NP. The response of the system to joint variations in flow rate, eluent composition and column temperature was investigated by means of Doehlert statistical experimental design. A model for retention of the analytes as a function of the experimental variables was proposed, and separation selectivity was studied. Selection of the optimal working zone was made through desirability function (D) calculations. Potential co-elution of 2-NP isomers with 4-NP1EO was considered when optimizing the separation. The occurrence of a restricted region of the experimental space where baseline resolution of analytes, associated impurities and internal standard results feasible (D not equal to 0) is apparent. PMID:17540387

  13. The Sr/Ca-temperature relationship in coralline aragonite: Influence of variability in (Sr/Ca)[sub seawater] and skeletal growth parameters

    SciTech Connect

    de Villiers, S.; Shen, G.T.; Nelson, B.K. (Univ. of Washington, Seattle, WA (United States))

    1994-01-01

    This paper provides an evaluation of two of the most likely pitfalls of Sr/Ca thermometry, i.e., the effect of biogenic cycling of Sr vs. Ca in the surface ocean and the effect of variable extension rate on Sr incorporation in coralline aragonite. The authors also report calibration of the Sr/Ca-temperature relationship for three coral species, Porites lobata, Pocillopora eydouxi, and Pavona clavus, collected for the Hawaiian and Galapagos islands. Analyses of seawater samples show significant spatial and depth variability in the Sr:Ca ratio. The uncertainty introduced by this effect is estimated to be <0.2[degrees]C for corals located in tropical oligotrophic waters, and potentially larger for corals located in upwelling areas. Sr/Ca along two different growth axes of a Galapagos Pavona clavus, with annual extension rates of [approximately]6 and 12 mm/y, respectively, indicate an offset of 1-2[degrees]C, with higher Sr/Ca values associated with slower extension rates. The offset observed between the two growth axes may be the result of variations in extension and/or calcification rate. These results are important in determining past sea surface temperatures for reconstruction of paleoclimates.

  14. Vertical and temporal variability in concentration and distribution of thaumarchaeotal tetraether lipids in Lake Superior and the implications for the application of the TEX86 temperature proxy

    NASA Astrophysics Data System (ADS)

    Woltering, Martijn; Werne, Josef P.; Kish, Jason L.; Hicks, Randall; Sinninghe Damsté, Jaap S.; Schouten, Stefan

    2012-06-01

    This study investigated the vertical and temporal distribution of Thaumarchaeota derived core isoprenoid glycerol dialkyl glycerol tetraether (GDGT) lipids through sampling and analysis of both suspended particulate matter from the water column at different times in the annual cycle and a 3 year long record of settling particles in two sediment traps at different depths at an open lake location in Lake Superior. Results from these analyses suggest that Thaumarchaeota were present throughout the water column during times of overturning, but mainly resided below the depth of the thermocline (20-40 m) during the period of thermal stratification. Fluxes of thaumarchaeotal produced GDGTs were highly periodic and mainly occurred during two periods of the annual cycle (winter and late spring/early summer). A covariance of both branched and isoprenoid GDGT fluxes with the mass accumulation flux combined with the observation that those periods of maximum fluxes were associated with increased BIT index values, however, suggest that these two periods of elevated fluxes may be related to an influx of resuspended particles transported from shallower near shore regions of Lake Superior. During all sampling periods TEX86 inferred temperatures from SPM were in good agreement with in situ water temperatures of the depths at which the SPM was sampled. The observed range of TEX86 inferred temperatures in 3 years of settling particles is relatively small and does not show significantly higher inferred temperatures during the thermally stratified period, indicating that the sedimentary TEX86 signal during the summer thermally stratified period mainly originated from depths below the relatively shallow thermocline. Additionally, TEX86 values during the winter period of increased fluxes did not capture the decrease in water temperatures observed throughout the water column during this period, and thus may be a further indication that the thaumarchaeotal lipid flux was the result of sediment focusing. Flux-weighted TEX86 inferred temperatures from both sediment traps were in good agreement with TEX86 temperatures from surface sediments from the same location in Lake Superior. Both flux weighted TEX86 temperatures from the sediment traps and average TEX86 temperatures from surface sediments were similar to averaged measured water temperatures at below ˜40 m depth within the error of the lacustrine TEX86 calibration. Based on the observed depths of Thaumarchaeota in the water column, TEX86 values in sediments of Lake Superior likely reflect a combination of mixed-season and sub-thermocline temperatures. This is effectively the same as the annual averaged water temperature observed at depths below 40 m in Lake Superior. Thus, trends in TEX86 inferred temperatures in sediment records of Lake Superior, and similar lakes, are likely to reflect subsurface temperature variability rather than that of surface temperatures.

  15. Alkenones and hydrogen isotopic composition of n-alkanes as indicators of past temperature and hydrological variability using lacustrine sediments from Lake Toyoni (Japan).

    NASA Astrophysics Data System (ADS)

    McColl, J. L.; Seki, O.; Couto, J.; Bendle, J. A.; Henderson, A. C. G.; Phoenix, V. R.; Toney, J. L.

    2014-12-01

    A better understanding of decadal to centennial climate variability is vital to improve the accuracy of near future climate prediction. Hokkaido represents a region which has limited paleo-climate data and is sensitive to climate change. Instrumental data shows a good correlation between the temporal variability of temperature and rainfall with the Pacific Decadal Oscillation (PDO) and the East Asian Summer Monsoon (EASM) however instrumental data is limited to the past ~150 years. Therefore down-core reconstructions of temperature and precipitation prior to instrumental records are required to provide a better understanding of the long-term behaviour of the PDO and EASM systems in this region. Lake Toyoni (Hokkaido, Japan) was investigated to provide high resolution lake temperature and hydrological reconstructions over the past 1000 years (1cm represents 3-8 years of sedimentation) using alkenones and the hydrogen isotopic composition of higher plant waxes (?D(HPW)), respectively. Lake Toyoni is the first lake from which alkenones are reported in Japan. C37 alkenone concentrations in surface sediments are 18?g C37 g?1 of dry sediment and the dominant alkenone is C37:4 . 18S DNA analysis revealed the presence of a single alkenone producer in Lake Toyoni and thus a single calibration for reconstructing lake temperature based on alkenone unsaturation patterns. Temperature reconstructions over the past 1000 years suggest lake water changes of 8-23°C which is in line with water temperature changes observed in Lake Toyoni. The molecular distributions and isotopic compositions of n-alkanes provide valuable paleo-environmental information. The dominant n-alkanes in Lake Toyoni are long chained (C25-C33) and are characterised by odd over even distribution. The source of long chained n-alkanes are from the surrounding terrestrial higher plants. Large fluctuations (~40‰) are documented in downcore ?D(HPW) representing hydrological changes in this region over the past 1000 years. These results suggest that alkenones and the ?D(HPW) preserved in Lake Toyoni record regional climate changes over decadal timescales. These fluctuations will be discussed in relation to globally recognised climate events, specifically the Medieval Warm Period and the Little Ice Age.

  16. The influence of carrier dynamics on double-state lasing in quantum dot lasers at variable temperature

    NASA Astrophysics Data System (ADS)

    Korenev, V. V.; Savelyev, A. V.; Zhukov, A. E.; Omelchenko, A. V.; Maximov, M. V.

    2014-12-01

    It is shown in analytical form that the carrier capture from the matrix as well as carrier dynamics in quantum dots plays an important role in double-state lasing phenomenon. In particular, the de-synchronization of hole and electron captures allows one to describe recently observed quenching of ground-state lasing, which takes place in quantum dot lasers operating in double-state lasing regime at high injection. From the other side, the detailed analysis of charge carrier dynamics in the single quantum dot enables one to describe the observed light-current characteristics and key temperature dependences.

  17. Impact of land convection on the water vapor and temperature variability in the TTL with an emphasis over Bauru (Brazil)

    NASA Astrophysics Data System (ADS)

    Carminati, F.; Ricaud, P.; Riviere, E.; Warner, J. X.; Attie, J. E.; August, T.; Michou, M.; Pommereau, J.

    2012-12-01

    A highly debated issue in the troposphere-to-stratosphere transport and processes controlling the water vapor (H2O) balance in the stratosphere is the role of deep overshooting over intense convective regions and interplay between hydration and dehydration processes in the Tropical Tropopause Layer (TTL). TRO-Pico is a 5-year project aiming to monitor the H2O amount during the wet season. The project relies on field campaigns held in Bauru (22.3°S; 49.1°W), Brazil, and involves a combination of balloon-borne measurements, ground-based and space-borne observations and modeling. More specifically, the study inter-compares over different time and spatial scales, the Vaisala RS-92GDP radiosondes, the Pico-SDLA and the Flash-B hygrometers datasets from the 2012 TRO-Pico campaign with the Aura-MLS limb sounder, the MetOp-IASI and the Aqua-AIRS nadir sounders, the Chemistry-Climate Model CNRM-CCM and the ECMWF analysis datasets. At the tropical scale, H2O evolution is influenced by two distinct regimes: 1) a tropospheric regime characterized by a vertical propagation, and strong negative (weakly positive) day-night variations in (non-) convective periods over land, and 2) a stratospheric regime with a propagation impacted by the 'Tape Recorder Effect' and small day-night variations, with a differentiation occurring approximately at the 360-K level of potential temperature. The temperature is subject to positive day-night variations over land increasing (decreasing) as the pressure decreases, with maximum amplitude above the Cold Point (CP) around 80 hPa in (non-) convective periods. At the local scale over Bauru, in convective periods, the shape of the diurnal cycle of H2O draws an early afternoon minimum in the Upper Troposphere (UT), consistent with the late afternoon maximum of convection. The diurnal cycle of temperature has a late morning minimum in the UT, shifted to the night at the CP level, also consistent with the injection of cold air by deep convection. Regarding the different H2O datasets, between 100 and 50 hPa we obtained a good consistency (within 10%) between MLS and the hygrometers while IASI overestimates from 2 to 3.5 ppmv (50-180%) the H2O content. The temperature is well depicted by IASI with respect to the hygrometers (within 3 K at the CP and less in the UT) but MLS measures a 4-K colder CP than IASI.

  18. Synthesis, spectral (IR, UV-Vis and variable temperature NMR) characterization and crystal structure of (N-benzyl-N-furfuryldithicarbamato-S,S?)(thiocyanato-N)(triphenylphosphine)nickel(II)

    NASA Astrophysics Data System (ADS)

    Valarmathi, P.; Thirumaran, S.; Sarmal, Lovely; Kant, Rajni

    2014-08-01

    Planar (N-benzyl-N-furfuryldithiocarbamato-S,S?)(thiocyanato-N)(triphenylphospine)nickel(II), [Ni(bfdtc)(NCS)(PPh3)], (1) was prepared from bis(N-benzyl-N-furfuryldithiocarbamato-S,S?)nickel(II), [Ni(bfdtc)2], (2) and characterized by elemental analysis, cyclic voltammetry, electronic, IR and variable temperature 1H and 13C NMR spectra. For complex 1, the thioureide vCsbnd N value is shifted to higher wavenumber compared to 2 and N13CS2 carbon signal observed for 1 is additionally shielded compared to the parent complex 2, suggesting increased strength of the thioureide bond due to the presence of the ?-accepting phosphine. In the room temperature 13C NMR spectrum of 1, two pseudo doublets are observed in the aliphatic region. Variable temperature 13C NMR spectral studies suggest that the fast thiocyanate exchange appears to be responsible for the appearance of pseudo doublets. Single crystal X-ray structural analysis of 1 and 2 confirm the presence of four coordinated nickel in a distorted square planar arrangement with the NiS2PN and NiS4 chromophores, respectively. The Nisbnd S bonds are symmetric in 2 (2.1914(14) and 2.2073(13) Å). But significant asymmetry in Nisbnd S bond distances was observed in 1 (2.2202(8) Å and 2.1841 Å). This observation clearly supports the less effective trans effect of SCN- over PPh3. Cyclic voltammetric studies revealed easier reduction of nickel(II) to nickel(I) in complex 1 compared to 2.

  19. A variable-temperature neutron diffraction study of ussingite; a strong asymmetric hydrogen bond in an aluminosilicate framework

    NASA Astrophysics Data System (ADS)

    Williams, E. R.; Weller, M. T.

    2012-06-01

    A powder neutron diffraction study of ussingite, Na2AlSi3O8(OH), over the temperature range 4-850 K has been undertaken. The strong hydrogen bond that exists in this mineral has been accurately determined with the O-H distance at 1.070(8) Å and an O(donor)-O(acceptor) separation of 2.481(5) Å at 4 K, The distribution of hydrogen along the O-O direction remains asymmetric between 4 and 850 K with the H atom being fully ordered at a single site, rather than partially disordered over two sites of a double-potential well, as in serandite. A gradual increase in the bonded O-H distance at higher temperatures is observed, indicative of a broadening of the potential well in which the hydrogen atom is sited. Below 50 K, the material shows negative thermal expansion, likely to be associated with reduced bending motion of the O-H bond.

  20. Spatial and temporal variability of ground surface temperature and active layer thickness at the margin of maritime Antarctica, Signy Island

    NASA Astrophysics Data System (ADS)

    Guglielmin, Mauro; Worland, Michael Roger; Cannone, Nicoletta

    2012-06-01

    A CALM grid with a data logger system to monitor the active layer thermal regime was established on Signy Island (60°43'S, 45°38'W at 80 m a.s.l.) in December 2005. The active layer at each of the 36 nodes of the grid was monitored measuring the ground temperature at least at 4 different depths between 0.02 and 0.4 m at the end of the summer season. In addition, within the grid, we selected four sites closely spaced (in a ray of 25 m) three of which with the same topographical characteristics (north facing aspect) but different vegetation coverage (one bare ground, BG1 and two sites with different vegetation: Andreaea sp. and Sanionia uncinata) and the fourth (BG2) it is as BG1 a bare ground but with south facing aspect. In particular, 4 thermistors were located at depths of 0.02, 0.3, 0.6, and 0.9 m at BG2 and at the Andreaea sp site, 9 thermistors at 0.02, 0.3, 0.6, 1, 1.2, 1.4, 1.6, 2, and 2.5 m at BG1 and at 0.02 and 0.6 m of depth at Sanionia site. Generally, with the same aspect, a thick vegetation cover (as in Sanionia site) provides a greater insulative effect than a thinner vegetation cover (as in Andreaea site) or bare ground (BG1) because vegetation both shades and insulates the ground resulting in a reduction in summer heat flux. Ground Surface Temperature (GST) was colder and more buffered in spring and summer under the vegetated ground than in BG1, although the coldest GST and lowest Thawing Degree Days (TDD) were recorded at BG2 and related to its southern aspect. Our data confirm that air temperature is the main driver of GST, as already reported both in the Arctic and Antarctic. We also found that the effect of air temperature changes seasonally, being drastically reduced in winter and, to a lesser extent, in fall and spring, when there is generally thin snow cover (< 30 cm). During the summer, when snow cover is usually absent, the air temperature is the dominant driver, although incoming radiation also had an effect on the northern exposed bare ground and to a lesser extent on the vegetated and southerly exposed bare ground. The active layer ranges between 81 and 185 cm on the 4 continuously monitored sites and, considering the sites with the same aspect, it is thicker under bare ground (between 10% up to more than 100%) than under vegetated ground, confirming previous observations in the Arctic and Antarctic. However at our sites, climate forcing has no effect on the active layer thickness, enhancing the role of soil properties including the periods of high moisture content and lateral flow of water. The lack of a statistically significant regressions between GST and active layer thickness could be due to the limited study period (four years) and/or to the variation with time of changes in soil characteristics such as soil moisture, and the possible occurrence of non-conductive heat transfer processes including the lateral flow of water. Further data are required to understand the role of moisture and possible ground water circulation within the active layer to explain the unexpected strong dichotomy between the GST regime and active layer thickness.

  1. Intra- and inter-individual variability of longitudinal daytime melatonin secretion patterns in depressed and non-depressed individuals.

    PubMed

    Bouwmans, Maria E J; Bos, Elisabeth H; Booij, Sanne H; van Faassen, Martijn; Oldehinkel, Albertine J; de Jonge, Peter

    2015-04-01

    Disrupted melatonin secretion is regarded as a link between circadian rhythm and major depression, but results have been contradictory. We hypothesize that this might be due to averaging across individuals and too short measurements periods. In this study, pair-matched depressed and non-depressed individuals sampled their saliva three times a day, 30 days, in their natural environment. The depressed group showed significantly more variance and higher melatonin levels (p?day-to-day variability was found. The individual time-series approach allowed us to reveal this variability. Important information remains unnoticed when analyzing melatonin only at the group level. PMID:25347155

  2. Heat waves frequency analysis and spatial-temporal variability of daily maximum temperature in southern Slovakia within the 1951, respectively 1961-2008 periods

    NASA Astrophysics Data System (ADS)

    Pecho, J.; Faško, P.; Mikulová, K.; Šâstný, P.

    2009-09-01

    Heat waves temporal and spatial analysis at selected meteorological stations in southern part of Slovakia within the 1951, respectively 1961-2008 periods is a goal of the presented contribution. It is expected that climate change in terms of global warming would amplify temporal frequency and spatial extension of extreme heat wave incidence in region of central Europe in the next few decades. The frequency of occurrence and amplitude of heat waves may be impacted by changes in the temperature regime. Heat waves can cause severe thermal environmental stress leading to higher hospital admission rates, health complications, and increased mortality. These effects arise because of one or more meteorology-related factors such as higher effective temperatures, sunshine, more consecutive hot days and nights, stagnation, increased humidity, increased pollutant emissions, and accelerated photochemical smog and particulate formation. Heat waves bring about higher temperatures, increased solar heating of buildings, inhibited ventilation, and a larger number of consecutive warm days and nights. All of these effects increase the thermal loads on buildings, reduce their ability to cool down, and increase indoor temperatures. The paper deals with analysis of temporal and spatial variability of heat waves occurrence at meteorological station Hurbanovo (time series of daily maximum air temperature available from at least 1901) and some other climatological stations in lowlands of southern Slovakia (Žiharec, Bratislava-airport, Jaslovské Bohunice, Kráľová pri Senci, etc.). We can characterize the heat waves by its magnitude and duration, hence both of these characteristics need to be investigated together using sophisticated statistical methods developed particularly for the analysis of extreme hydrological events. These methods are quite similar to the intensity-duration-frequency approach often used in the analysis of extreme precipitation events. The HDF-curves (heatwave-duration-frequency curves) defining relation between duration and return period of heat wave is usually modelled utilizing the general extreme value distribution (GEV).

  3. Impact of land convection on the water vapor and temperature variability in the TTL with an emphasis over Bauru (Brazil)

    NASA Astrophysics Data System (ADS)

    Carminati, Fabien; Ricaud, Philippe; Pommereau, Jean Pierre; Khaykin, Serguey; Rivière, Emmanuel; Warner, Juying; Attié, Jean-Luc; Saint-Martin, David; Michou, Martine; August, Thomas

    2013-04-01

    A highly debated issue in the troposphere-to-stratosphere transport and processes controlling the water vapor (H2O) balance in the stratosphere is the role of deep overshooting over intense convective regions and interplay between hydration and dehydration processes in the Tropical Tropopause Layer (TTL). TRO-Pico is a 5-year project aiming to monitor the H2O amount during the wet season. The project relies on field campaigns held in Bauru (22.3°S; 49.1°W), Brazil, and involves a combination of balloon-borne measurements, ground-based and space-borne observations and modeling. More specifically, the MetOp-IASI and Aqua-AIRS nadir sounders datasets in the Upper Troposphere (UT) and the Aura-MLS limb sounder datasets in the Lower Stratosphere (LS) are inter-compared over long time ranges and different spatial scales to the Chemistry-Climate Model CNRM-CCM and the ECMWF analysis datasets, together with the balloon-borne sensors: Vaisala RS-92GDP radiosondes, Pico-SDLA and Flash-B hygrometers. In the tropical band (30°S-30°N), during convective seasons, we show in the UT strong negative day-night variations of H2O over Southern continents, consistent with the diurnal cycle of convective events, and, to a lesser extent, also over Northern continents. In the LS, during convective periods, the H2O signal becomes slightly positive over Southern continents and of an opposite sign over the Northern continents. The temperature fields show positive day-night variations over land increasing with altitude, with a maximum amplitude above the Cold Point (CP) around 80 hPa. At the local scale over Bauru, we sampled the different datasets over 24 hours to highlight the shape of the diurnal cycle of H2O. An early afternoon minimum is observed in the UT, consistent with the late afternoon maximum of convection. The diurnal cycle of temperature has a late morning minimum in the UT, shifted to the night at the CP level, also consistent with the injection of cold air by deep convection. Regarding the different H2O datasets, between 100 and 50 hPa, we obtain a good consistency (within 10%) between MLS and the hygrometers while IASI overestimates from 2 to 3.5 ppmv (50-180%) and AIRS underestimates from 1 to 1.5 ppmv (50-60%) the H2O content. The temperature is well reproduced by IASI and AIRS with respect to the hygrometers, within 3 K at the CP and less (~1 K) in the UT.

  4. Seasonal to Decadal-Scale Variability in Satellite Ocean Color and Sea Surface Temperature for the California Current System

    NASA Technical Reports Server (NTRS)

    Mitchell, B. Greg; Kahru, Mati; Marra, John (Technical Monitor)

    2002-01-01

    Support for this project was used to develop satellite ocean color and temperature indices (SOCTI) for the California Current System (CCS) using the historic record of CZCS West Coast Time Series (WCTS), OCTS, WiFS and AVHRR SST. The ocean color satellite data have been evaluated in relation to CalCOFI data sets for chlorophyll (CZCS) and ocean spectral reflectance and chlorophyll OCTS and SeaWiFS. New algorithms for the three missions have been implemented based on in-water algorithm data sets, or in the case of CZCS, by comparing retrieved pigments with ship-based observations. New algorithms for absorption coefficients, diffuse attenuation coefficients and primary production have also been evaluated. Satellite retrievals are being evaluated based on our large data set of pigments and optics from CalCOFI.

  5. Reconstructing Late Pleistocene air temperature variability based on branched GDGTs in the sedimentary record of Llangorse Lake (Wales)

    NASA Astrophysics Data System (ADS)

    Maas, David; Hoek, Wim; Peterse, Francien; Akkerman, Keechy; Macleod, Alison; Palmer, Adrian; Lowe, John

    2015-04-01

    This study aims to provide a temperature reconstruction of the Lateglacial sediments of Llangorse Lake. A new temperature proxy is used, based on the occurrence of different membrane lipids of soil bacteria (de Jonge et al., 2014). Application of this proxy on lacustrine environments is difficult because of in situ (water column) production and co-elution of isomers. Pollen analysis provides a palynological record that can be used for biostratigraphical correlation to other records. Llangorse Lake lies in a glacial basin just northeast of the Brecon Beacons in Powys, South Wales. The lake is located upstream in the Afon Llynfi valley, at the edge of the watershed of the River Wye. The lake consists of two semi-separated basins with a maximum water depth of 7.5 m, arranged in an L-shape with a surface area of roughly 1.5 km2. Previous studies have focused on the Holocene development of the lake and its surrounding environment (Jones et al., 1985). This study focuses on the deglacial record that appeared to be present in the basal part of the sequence. The lake was cored in the September, 2014 with a manual operated 3 m piston corer from a small coring platform. Overlapping cores were taken to form a continuous 12 m core, spanning the Holocene and the Lateglacial sediments. Six adjacent Lateglacial core segments from the southern basin of Llangorse lake were scanned for their major element composition using XRF scanning at 5 mm resolution to discern changes in sediment origin. Furthermore, loss on ignition (LOI) analysis was used to determine the changes in organic content of the sediments. Subsamples of the Lateglacial sedimentary record were analyzed for the occurrence of different bacterial membrane lipids (brGDGTs: branched glycerol dialkyl glycerol tetraethers) by means of HPLC-MS (high performance liquid chromatography and mass spectrometry) using two silica columns to achieve proper separation of isomers (de Jonge et al., 2013). Air temperatures are reconstructed using a multiple linear regression index based on the relative abundance of the brGDGTs. This allows for the quantification of the temperature fluctuation in the events leading up to the Holocene warming, especially the Interstadial (GI-1) warming, subsequent Stadial (GS-1) cooling and eventual transition into the Interglacial period. References: Jones, R., Benson-Evans, K. and Chambers, F.M. (1985) Human influence upon sedimentation in Llangorse Lake, Wales, Earth Surface Processes and Landforms, Vol 10, p 227-235 De Jonge, C., Hopmans, E., Zell, C.I., Kim, J-H., Schouten, S. and Sinninghe-Damsté, J. (2014) Occurrence and abundance of 6-methyl branched glycerol dialkyl glycerol tetraethers in soils: Implications for palaeoclimate reconstruction, Geochimica et Cosmochimica Acta, Vol 141, p 97-112 De Jonge C., Hopmans E. C., Stadnitskaia A., Rijpstra W. I. C., Hofland R., Tegelaar E. and Sinninghe-Damste, J.S. (2013) Identification of novel penta- and hexamethylated branched glycerol dialkyl glycerol tetraethers in peat using HPLC-MS2, GC-MS and GC-SMB-MS. Organic Geochemistry, Vol 54, p 78-82.

  6. Variable responses of benthic communities to anomalously warm sea temperatures on a high-latitude coral reef.

    PubMed

    Bridge, Tom C L; Ferrari, Renata; Bryson, Mitch; Hovey, Renae; Figueira, Will F; Williams, Stefan B; Pizarro, Oscar; Harborne, Alastair R; Byrne, Maria

    2014-01-01

    High-latitude reefs support unique ecological communities occurring at the biogeographic boundaries between tropical and temperate marine ecosystems. Due to their lower ambient temperatures, they are regarded as potential refugia for tropical species shifting poleward due to rising sea temperatures. However, acute warming events can cause rapid shifts in the composition of high-latitude reef communities, including range contractions of temperate macroalgae and bleaching-induced mortality in corals. While bleaching has been reported on numerous high-latitude reefs, post-bleaching trajectories of benthic communities are poorly described. Consequently, the longer-term effects of thermal anomalies on high-latitude reefs are difficult to predict. Here, we use an autonomous underwater vehicle to conduct repeated surveys of three 625 m(2) plots on a coral-dominated high-latitude reef in the Houtman Abrolhos Islands, Western Australia, over a four-year period spanning a large-magnitude thermal anomaly. Quantification of benthic communities revealed high coral cover (>70%, comprising three main morphospecies) prior to the bleaching event. Plating Montipora was most susceptible to bleaching, but in the plot where it was most abundant, coral cover did not change significantly because of post-bleaching increases in branching Acropora. In the other two plots, coral cover decreased while macroalgal cover increased markedly. Overall, coral cover declined from 73% to 59% over the course of the study, while macroalgal cover increased from 11% to 24%. The significant differences in impacts and post-bleaching trajectories among plots underline the importance of understanding the underlying causes of such variation to improve predictions of how climate change will affect reefs, especially at high-latitudes. PMID:25426718

  7. Study of stereodynamics by variable-temperature ZVPt NMR spectroscopy. Diastereomerism in platinum(II) thioether complexes and solvent effects

    SciTech Connect

    Galbraith, J.A.; Menzel, K.A.; Ratilla, E.M.A.; Kostic, N.M.

    1987-07-01

    New (PtCl3(thioether)) complexes have been synthesized with the following thioethers as unidentate ligands: N-formyl-DL-homomethionine (FHMetH), N-acetyl-L-methionine (AcMetH), N-acetyl-S-methyl-DL-cysteine (AcMeCysH), DL-3-(methylthio)-1,2-propanediol (MTPD), and DL-3-(methylthio)-2-butanone (MTB). These complexes constitute a series in which the length of the (CH2)/sub x/ chain connecting the chiral carbon and sulfur atoms is varied systematically: x = 3,2,1,1, and 0, respectively. Each of the complexes exists in two diastereomeric forms, which are related by intramolecular inversion of configuration at the coordinated sulfur atom. The diastereomers are clearly evident in the ZVPt NMR spectra, whose dependence on temperature yields the G/sup double dagger/ values for inversion. Stereodynamic processes involving all but the simplest thioether ligands and processes resulting in subtle changes in molecular structure proved intractable by the common H and TC NMR methods. The barrier to inversion depends on the solvating ability of the medium in an interesting way. Small amounts of diglyme in aqueous solution reduce the difference in chemical shifts between the ZVPt NMR peaks of the diastereomers and thus lower the coalescence temperature, but they do not affect the barrier significantly, Large amounts of diglyme, however, lessen the stabilizing effect of hydration upon the thioether complex and lower the barrier. In unidentate complexes, which have flexible structures, the chiral C atom provides virtually no discrimination between the two configurations of the chiral S atom irrespective of the length of the (CH2)/sub x/ chain between the two atoms. Significant discrimination is evident, however, in the bidentate complex cis-(PtCl2(MeCysH)). Steric constraint, such as that provided by chelation, seems to be a prerequisite for chiral discrimination.

  8. Decadal- and Centennial-Scale Variability in Sea Surface Temperature in Beppu Bay in Japan During the Last 2900 Years

    NASA Astrophysics Data System (ADS)

    Yamamoto, M.; Kuwae, M.; Abe, M.; Ichikawa, N.

    2012-12-01

    We generated 8-year-resolution records of paleotemperatures using UK37? and TEX86 and discuss the decadal and centennial changes in winter and summer sea surface temperatures (SSTs) in Beppu Bay, Kyushu Island, Japan. Beppu Bay is a silled basin filled with oxygen-deficient bottom water. Because of anoxic environment, organic matter is well preserved in sediments and bioturbation is limited. Fourteen piston and gravity cores were retrieved at the center of the basin. Correlation of cores was conducted using sand and silt seams, and the age-depth model was created by wiggle-matching of forty-two AMS radiocarbon dates from bivalve mollusk shells and excess Pb-210 and Cs-137 concentrations. The sedimentation rates were 230-300 cm/ky. TEX86 and UK37? records show different patterns, but both have a similar multi-decadal periodicity. The temperature estimated by TEX86 at the core-top sample is lower than mean annual SST, implying that TEX86 reflects the SST weighted in winter. That by UK37? corresponds to the SST weighted in summer. UK37? shows multi-decadal and centennial-scale variation interrupted by frequent short-term cool periods. The periods corresponded to volcanic eruptions recorded in a Greenland ice core. TEX86 shows multi-decadal variation that is consistent with a proxy PDO record reconstructed from North American tree-rings. Beppu Bay sediments are a good climate archive to provide high-resolution summer and winter SST records in the northwestern Pacific region.

  9. Design and performances of a shielded liquid helium insert with an optically heated variable temperature stage for the study of low frequency magnetic noise in HT_c superconductors

    Microsoft Academic Search

    X. Ridereau; M. Lam Chok Sing; D. Bloyet

    2001-01-01

    We have designed and built a liquid helium immersion insert which is magnetically shielded from the ambient magnetic field fluctuations by the use of a superconducting lead can. The insert has a variable temperature stage made of sapphire which is optically heated by the light guided from an external lamp via a glass rod. The temperature regulation is achieved by

  10. Short-term climate prediction for South-Western Siberia, based on comparison of reconstructed annual temperature variability between recent 430 yrs interval and Roman era warming

    NASA Astrophysics Data System (ADS)

    Kalugin, I.; Daryin, A.; Babich, V.; Myglan, V.; Ovchinikov, D.

    2009-04-01

    The new microstratigraphic and chronological approaches became available for research of sediment records in situ due to automated high resolution analytical technique for the last 10 years. It provides to obtain continuous series of several physical and chemical parameters along the fresh opened core and in solid preparates as well. Scanning X-ray fluorescence analysis on synchrotron radiation (SR-XRFA) as a high-efficiency method of microelement analysis is adapted to determine more than 35 elements with minimal step 0.1 mm. So it allows revealing intraannual variability of parameters as well as annual- multiannual changes after smoothing. Teletskoye Lake sediments are studied for the inference of a robust record of climatically driven solid detrital supply from the catchment, because there is no industry and agriculture in this almost non populated area. Sedimentation is rather continuous here because annual clastic supply and deposited mass are the same. The Teletskoye Lake (51°39'N, 87°40'E, 434 m a.s.l.,) is a tectonic lake in the northern part of the Altai Mountains. It has a length of 78 km, a width of 3-5 km and an average depth of 174 m and has a dimictic mixing regime. The combination of extracting sub millimeter resolution SR-XRFA data, isotope Cs-Pb-C age models, and regression based calibration methods were used to reconstruct past environmental changes for the last 3100 yrs beyond instrumental and tree ring limits. Geochemical parameters used as environmental proxies were following. Br content appeared to be broadly correlative with mean annual temperature variations because of changes of vegetation productivity in catchment. Sr/Rb ratio and Ti content reflected the proportion of the unweathered terrestrial fraction. X-ray density (XRD) appeared to reflect water yield regime and sediment flux. Multiple regression analysis was applied on normalized values in order to obtain the environmental reconstruction. Calibration was conducted with Barnaul instrumental temperature and precipitation data for 1840-1991, with lake level measurements in Yailu station for 1930-2006, with local dendrochronologies and other time series. Before calibration linear scale was transformed to time scale using XRD values as a portion of water content for correction on each step. Both time series of proxies and environmental data were preliminary smoothed by the same run average according to desired time scale. Variability of annual temperature and of generalized climate index (Dev. T - Dev. P) [1] was considered to search analogues between recent and past time intervals. The best coincidence was obtained for intervals 310BC - 120AD and 1560-1990AD, where correlation coefficient amounted to 0, 44 for 2000 points. The more smoothing of source data was applied - the correlation was higher. Also, sum of single periodicities after spectral Fourier analysis of primary time series showed the same results. Taking into account this good coincidence, the prolongation of the past temperature profile (moved forward on 1870 years) is possible to consider as predicted time interval after AD1990. The authentic duration of prediction may be accepted not less than 10% of compared time intervals i.e. 40 years. Certainly, it concerns only to natural component of climate variability. Real excess of temperature ~2oC in AD1990-2005 is explained by human impact. [1] I. Kalugin et al. The 800 year long annual records of air temperature and precipitation over Southern Siberia inferred from high-resolution time-series of Teletskoye Lake sediments. Quaternary Research. 67 (2007) 400-410.

  11. An unsteady-state method for determining overall coefficient of heat transfer (k-value) of insulated bodies at variable external temperatures

    NASA Astrophysics Data System (ADS)

    Gvozdenac, Dušan

    2015-02-01

    A method for determining k-value of insulated bodies at variable external temperatures is proposed, theoretically described and results of experimental verification are presented in this paper. Theoretical analyses include descriptions of both physical and mathematical models and definition of the extrapolation formula. The method is tested in laboratory conditions on a simple model of insulated chamber and compliance with all testing conditions prescribed by Agreement on Transport of Perishables. The advantage of this method in comparison to any other unsteady- or steady-state method is that it enables k-value determination out of the specialized test stations. This further makes it possible to carry out cheaper and more frequent k-value measurements/control in insulated bodies. Also, the proposed method can be used for testing the k-value of stationary insulated chambers which cannot be objectively tested by means of stationary methods.

  12. Temperature and Productivity Variability Along the Southwestern Portuguese Margin During the Onset of the Mid-Pleistocene Transition

    NASA Astrophysics Data System (ADS)

    Salgueiro, E.; Voelker, A. H. L.; Abrantes, F. F. G.; Rodrigues, T.; Sierro, F. J.; Hodell, D. A.; Alberto, A.; Freitas, P. S.

    2014-12-01

    The Southwest Portuguese Margin sedimentary record is influenced by the Mediterranean Outflow Water (MOW), with a strong thermohaline signature occurring between 500 and 1500m water depth. Variations of MOW intensity during the Late Quaternary (±750ky) are related to changes in the global climate and in the North Atlantic thermohaline circulation. To validate the sedimentary climate records on the Southwestern Portuguese Margin we performed a regional core-top multi-proxy study (Corg, CaCO3, grain size, foraminifera abundances, stable isotopes) to distinguish the MOW effects in recent sediments. The influence of this high velocity bottom current is marked in sediments by a strong increase of the sand content at both, the upper and lower, MOW boundaries. An increase of fine sediments is due to winnowing by the current, resulting in a drastic change in the accumulation rates of any sand-sized biogenic particle. For this reason, some of the traditional productivity proxies used such as Corg, planktonic and benthic foraminifera total abundances, should not be used at sites under the influence of contour currents. However, we demonstrate that the planktonic foraminifera relative abundances can be used with confidence because they are independent of the action of the MOW. Based on the planktonic foraminifera assemblages in two IODP Sites, U1387 recovered from the MOW influenced Faro Drift, and U1385 recovered at 2578m, we reconstruct the sea surface temperature (SST) and export productivity (Pexp) during the beginning of the Mid-Pleistocene Transition, Marine Isotope Stages 36 and 35. At Site U1387: i) foraminifera-derived SST was compared with biomarkers SST and foraminiferal ?18O data; ii) foraminifera-derived Pexp was compared with the Corg; and iii) the influence of the MOW on the sediments was deducted from the weight percent of the sand fraction, indicating contourite layers, and the benthic foraminiferal ?18O and ?13C data.

  13. Recent Patterns of Antarctic Surface Air Temperature Trends in the Context of Natural Variability, as Simulated by the CMIP5 Models

    NASA Astrophysics Data System (ADS)

    Smith, K. L.; Polvani, L. M.; de O Lobo, A.

    2014-12-01

    One of the hallmarks of climate change in recent decades has been the dramatic warming of the Western Antarctic Ice Sheet (WAIS), whereas the Eastern AIS (EAIS) has experienced a slight, and insignificant cooling trend. Here we examine the extent to which this spatial asymmetry in Antarctic surface air temperature (SAT) trends might be a response to anthropogenic climate forcings, such as greenhouse gas emissions and ozone depletion, or rather the manifestation of large natural climate variability. We compare the observed annual mean Antarctic SAT over the 1960-2005 and 1979-2005 time periods to SAT data from 40 Coupled Model Intercomparison Project Phase 5 (CMIP5) historical integrations. We find that the CMIP5 multi-model mean shows near-homogeneous warming throughout Antarctica, i.e. it lacks the observed spatial asymmetry between WAIS and EAIS. As the multi-model mean is, by construction, the forced response, we conclude that the observed spatial asymmetry in Antarctic SAT results from natural variability, which acts to mask the anthropogenic warming in the EAIS region, while amplifying the WAIS warming. In addition, contrasting historical (i.e., forced) and pre-industrial (i.e., control) integrations from these same 40 CMIP5 models, we show that the observed total Antarctic and EAIS SAT trends fall well within the distribution of trends arising naturally in the system, and that the forced response in the models is small compared to the natural variability. In contrast, we do find that the WAIS SAT trend is more likely driven by anthropogenic forcings.

  14. Variability of 4-Monomethylsterols and 4,4'-Dimethylsterols in Olive Oil and Their Use as Indicators of Olive Variety, Ripening Degree, and Oil Storage Temperature.

    PubMed

    Luki?, Marina; Luki?, Igor; Sladonja, Barbara; Piližota, Vlasta

    2015-06-10

    To investigate the variability of 4-monomethylsterols and 4,4'-dimethylsterols in olive oil as a result of variety, ripening, and storage temperature, 36 samples were subjected to gas chromatography with flame ionization detection (GC-FID) and with mass spectrometric detection (GC-MS), and results were processed by univariate and multivariate statistics. Relative amounts (percent) of ?-amyrin, cycloartenol, and 24-methylenecycloartanol accounted for the most variation due to variety, while citrostadienol (percent) and 24-methylenecycloartanol (milligrams per 100 g) were strongly affected by ripening. Multivariate statistics differentiated olive oils regardless of storage conditions, which implied the possibility to use 4-monomethyl- and 4,4'-dimethylsterols as indicators of variety and ripening degree for fresh and stored oils. Absolute changes in 4-monomethyl- and 4,4'-dimethylsterols after storage were of a much smaller magnitude, meaning the investigated olive oils essentially retained health-beneficial features that derive from these compounds. Relative changes caused by storage were specific for each storage temperature and were useful in discriminating oils by linear discriminant analysis. PMID:25980671

  15. A variable temperature study of the transport properties of aqueous solutions of VOSO4 and NH4VO3 in 2 M H2SO4

    NASA Astrophysics Data System (ADS)

    Suarez, Sophia; Sahin, Meriam; Adam, Yara; Moussignac, Lucy; Cuffari, David; Paterno, Domenec

    2015-02-01

    Variable temperature ionic conductivity, viscosity and 1H NMR spin-lattice relaxation times, linewidths and chemical shifts measurements were determined for various concentrations of aqueous ammonium metavanadate (NH4VO3) and vanadyl sulfate (VOSO4) over the temperature range of 20-100 °C. Concentration ranges of 0.05-2 M and 0.05-0.2 M were investigated for VOSO4 and NH4VO3 respectively in 2 M H2SO4. Results show ion and proton transport processes that are mediated strongly by increasing solution viscosity, especially in the case of VOSO4. Activation energies calculated from ionic conductivity and solution viscosity show greater energy being needed for translational ion dynamics with increasing concentration for both solutions. Additionally, data suggest that with greater metal ion concentration ion association is more prevalent for the vanadyl ion. The differences between the transport capabilities of the two solution are discussed in terms of the 1H NMR, ionic conductivity and viscosity data.

  16. Potential Predictability of the Sea-Surface Temperature Forced Equatorial East Africa Short Rains Interannual Variability in the 20th Century

    NASA Astrophysics Data System (ADS)

    Bahaga, T. K.; Gizaw, G.; Kucharski, F.; Diro, G. T.

    2014-12-01

    In this article, the predictability of the 20th century sea-surface temperature (SST) forced East African short rains variability is analyzed using observational data and ensembles of long atmospheric general circulation model (AGCM) simulations. To our knowledge, such an analysis for the whole 20th century using a series of AGCM ensemble simulations is carried out here for the first time. The physical mechanisms that govern the influence of SST on East African short rains in the model are also investigated. It is found that there is substantial skill in reproducing the East African short rains variability, given that the SSTs are known. Consistent with previous recent studies, it is found that the Indian Ocean and in particular the western pole of the Indian Ocean dipole (IOD) play a dominant role for the prediction skill, whereas SSTs outside the Indian Ocean play a minor role. The physical mechanism for the influence of the western Indian Ocean on East African rainfall in the model is consistent with previous findings and consists of a gill-type response to a warm (cold) anomaly that induces a westerly(easterly) low-level flow anomaly over equatorial Africa and leads to moisture flux convergence (divergence) over East Africa. On the other hand, a positive El Nino-Southern Oscillation (ENSO) anomaly leads to a spatially non-coherent reducing effect over parts of East Africa, but the relationship is not strong enough to provide any predictive skill in our model. The East African short rains prediction skill is also analyzed within a model-derived potential predictability framework and it is shown that the actual prediction skill is broadly consistent with the model potential prediction skill. Low-frequency variations of the prediction skill are mostly related to SSTs outside the Indian Ocean region and are likely due to an increased interference of ENSO with the Indian Ocean influence on East African short rains after the mid-1970s climate shift.

  17. AIRS high-resolution stratospheric temperature retrievals evaluated with operational Level-2 data and ERA-Interim

    NASA Astrophysics Data System (ADS)

    Meyer, Catrin I.; Hoffmann, Lars

    2015-04-01

    The Atmospheric InfraRed Sounder (AIRS) aboard NASA's Aqua satellite provides stratospheric temperature observations for a variety of scientific tasks. However, the horizontal resolution of the operational temperature retrievals is generally not sufficient for studies of gravity waves. The retrieval discussed here provides stratospheric temperature profiles for each individual AIRS footprint and therefore has nine times better horizontal sampling than the operational data. The retrieval configuration is optimized so that the results provide a trade-off between spatial resolution and retrieval noise which is considered optimal for gravity wave analysis. Here the quality of the high-resolution data is assessed by comparing a nine-year record (2003 - 2011) of stratospheric temperatures with results from the AIRS operational Level-2 data and the ERA-Interim meteorological reanalysis. Due to the large amount of data we performed a statistical comparison of the high-resolution retrieval and reference data sets based on zonal averages and time-series. The temperature data sets are split into day and night, because the AIRS high-resolution retrieval uses different configurations for day- and night-time conditions to cope with non-LTE effects. The temperature data are averaged on a latitudinal grid with a resolution of one degree. The zonal averages are calculated on a daily basis and show significant day-to-day variability. To further summarize the data we calculated monthly averages from the daily averaged data and also computed zonal means. Additionally, the standard deviation of the three data sets was computed. The comparisons show that the high-resolution temperature data are in good agreement with the reference data sets. The bias in the zonal averages is mostly within ± 2 K and reaches a maximum of 7 K to ERA-Interim and 4 K to the AIRS operational data at the stratopause, which is related to the different resolutions of the data sets. Variability is nearly the same in all three data sets, having maximum standard deviations around the polar vortex in the mid and upper stratosphere. The evaluation presented here indicates that the high-resolution temperature retrievals are well-suited for scientific studies and that they will become a valuable asset for further studies of stratospheric gravity waves. Reference: Meyer, C. I. and L. Hoffmann, Validation of AIRS high-resolution stratospheric temperature retrievals, Proc. SPIE 9242, Remote Sensing of Clouds and the Atmosphere XIX; and Optics in Atmospheric Propagation and Adaptive Systems XVII, 92420L (17 October 2014); doi: 10.1117/12.2066967

  18. Estimation of Surface Heat Fluxes at Field Scale Using Surface Layer Versus Mixed-Layer Atmospheric Variables with Radiometric Temperature Observations.

    NASA Astrophysics Data System (ADS)

    Kustas, William P.; Prueger, John H.; Humes, Karen S.; Starks, Patrick J.

    1999-02-01

    Radiometric surface temperature observations TR(), near-surface meteorological/surface energy flux (METFLUX), and atmospheric boundary layer (ABL) data were collected during the Washita '94 Experiment conducted in the Little Washita Experimental Watershed near Chickasha, Oklahoma. The TR() measurements were made from ground and aircraft platforms near the METFLUX stations located over vegetated surfaces of varying amounts of cover and over bare soil. Continuous, half-hourly averaged ground-based TR() measurements essentially at the point scale were calibrated with periodic ground transect and aircraft-based TR() observations at coarser resolutions so that the continuous TR() measurements would be representative of surface temperatures at the field scale (i.e., on the order of 104 m2). The METFLUX data were collected nominally at 2 m above the surface, while ABL measurements were made in the lower 8-10 km of the atmosphere. The `local' wind speed, u, and air temperature, TA, from the METFLUX stations, as well as the mixed-layer wind speed, UM, and potential temperature, M, were used in a two-source energy balance model for computing fluxes with continuous TR() measurements from the various surfaces. Standard Monin-Obukhov surface layer similarity was used with the `local' u and TA data from the METFLUX stations. Bulk similarity approaches were used with the UM and M data referenced either to ABL height or the top of the surface layer. This latter approach of using mixed-layer data to drive model computations for the different sites is similar to the so-called flux-aggregation schemes or methods proposed to account for subgrid variability in atmospheric models, such as the`tile' or `mosaic' approach. There was less agreement between modeled and measured fluxes when using mixed-layer versus local meteorological variables data for driving the model, and the type of bulk formulation used (i.e., whether local or regional surface roughness was used) also had a significant impact on the results. Differences between the flux observations and model predictions using surface layer similarity with local u and TA data were about 25% on average, while using the bulk formulations with UM and M differences averaged about 30%. This larger difference was caused by an increase in biases and scatter between modeled and measured fluxes for some sites. Therefore, computing spatially distributed local-scale fluxes with ABL observations of mixed-layer properties will probably yield less reliable flux predictions than using local meteorological data, if available. Given the uncertainty in flux observations is about 20%, these estimates are still considered reasonable and moreover permit the mapping of spatially distributed surface fluxes at regional scales using a single observation of UM and M with high resolution TR() data. Such TR() observations with a 90-m pixel resolution will be available from the Advanced Spaceborne Thermal Emission and Reflection Radiometer to be launched on NASA's Earth Observing System.

  19. Regional temperature, atmospheric circulation, and sea-ice variability within the Younger Dryas Event constrained using a speleothem from northern Iberia

    NASA Astrophysics Data System (ADS)

    Baldini, Lisa M.; McDermott, Frank; Baldini, James U. L.; Arias, Pablo; Cueto, Marián; Fairchild, Ian J.; Hoffmann, Dirk L.; Mattey, David P.; Müller, Wolfgang; Nita, Dan Constantin; Ontañón, Roberto; Garciá-Moncó, Cristina; Richards, David A.

    2015-06-01

    Precisely-dated, high-resolution stable isotope and trace element data from a stalagmite from La Garma Cave, northern Spain, reveal several stages of distinct climatic variability along the northern Iberian Atlantic margin, and provide new constraints on the latitude of North Atlantic westerlies during the Younger Dryas Event (YD). Westerly wind position (reconstructed using sub-annually resolved Mg data as a proxy for sea spray contributions associated with wind strength at this coastal cave site) during the early YD (12.85-12.15 kyr) oscillated meridionally, resembling the decadal-scale component of the modern North Atlantic Oscillation (NAO). Northward repositioning of westerly storm tracks over northern Iberia began at ?12.15 kyr, consistent with other high-resolution wind proxy reconstructions from central and northern Europe, but occurred more gradually nearer the Atlantic margin. From ?12.15 kyr to the YD termination, atmospheric circulation resembled a persistently positive NAO, with westerlies reaching their maximum northward extent at 11.8 kyr (reflected by a Mg concentration minimum at this time). Air temperature (reflected by our ?18O data) and Iberian wind strength were predominantly coupled throughout the YD suggesting that temperature modulated sea-ice extent, and consequently controlled westerly wind latitude. However our data suggest that abrupt warming at 12.1 kyr was followed by much more gradual northward shifts in westerly position, and that a lag existed between the warming and sea-ice retreat. This gradual return of the westerlies to the north beginning at 12.1 kyr is consistent with inferred changes in wind strength at other European sites. Additionally, atmospheric circulation inferred from our northern Iberian wind strength proxy record generally tracked low-frequency meridional shifts in Intertropical Convergence Zone position, corroborating past research that suggested closely coupled low- and high-latitude atmospheric teleconnections over this period.

  20. Influence of Dopants on Electrical Properties of ZnO-V2O5 Varistors Deduced from AC Impedance and Variable-Temperature Dielectric Spectroscopy

    NASA Astrophysics Data System (ADS)

    Wu, Jun; Li, Taotao; Qi, Ting; Qin, Qingwei; Li, Guangqiang; Zhu, Bailin; Wu, Run; Xie, Changsheng

    2012-07-01

    The influence of MnO2, PbO, and a mixture of MnO2, PbO, and B2O3 on the electrical and dielectric properties of ZnO-V2O5 ceramics was studied by alternating-current (AC) impedance and variable-temperature dielectric spectroscopy. The results show that, compared with the resistivity of the intervening layer at the grain boundary, the Schottky barrier present at the grain boundary is much more important for varistor performance, which can be significantly improved by using a mixture of MnO2, PbO, and B2O3. Consequently, better varistor performance is achieved for 94.5 mol.% ZnO + 0.5 mol.% V2O5 + 1.0 mol.% MnO2 + 2.0 mol.% PbO + 2.0 mol.% B2O3 (ZVMPB), i.e., nonlinear coefficient ? = 35.3 and leakage current density I l = 2.72 ?A/cm2. The activation energy for the characteristic dielectric relaxation process is in the range of 0.339 eV to 0.365 eV, indicating that it is only associated with oxygen vacancy V{O/·}.

  1. Temperature, vegetation and precipitation variability in the Nile River drainage during the past 27,000 years: Insights from molecular and isotopic proxies

    NASA Astrophysics Data System (ADS)

    Castañeda, Isla; Schouten, Stefan; Pätzold, Jürgen; Schefuß, Enno

    2013-04-01

    The paleoclimate history of the Eastern Mediterranean (EM) region is of much interest due to its long history of human occupation. To date, much of our knowledge of past climate in the EM region comes from marine sedimentary records. These indicate that since the Last Glacial Maximum, major and sometimes abrupt sea surface temperature (SST) fluctuations occurred in response to global climate events including the Younger Dryas (YD), the Bølling-Allerød, and Heinrich Event 1 (H1). In comparison, less is known regarding continental paleoclimate conditions in this region due to a scarcity of well-dated continuous climate archives, particularly from Saharan North Africa. Here, we present new reconstructions of continental precipitation (plant leaf wax ?D), C3 vs. C4 vegetation (plant leaf wax ?13C) and soil temperature (MBT/CBT paleothermometer) in the Nile River catchment in conjunction with previously published U37k' and TEX86SST reconstructions from the EM Sea. Our multiproxy records indicate that relative to the present, the LGM was characterized by arid conditions with cooler SST and soil temperatures in the catchment. The H1 event stands out as a major excursion in nearly all proxies and is characterized by an abrupt decrease in SST and the most arid conditions of the past 27,000 years. The African Humid Period (AHP) of the early Holocene is the wettest interval of the entire record and is observed from ~10,000 to 5,500 cal BP, with maximum wet conditions noted at ~8,000 cal BP. Interestingly, a rather abrupt cooling is noted in the MBT/CBT record at ~5.5 cal kyr, coinciding with the end of the AHP off west Africa; however, the transition out of the AHP is more gradual in the ?D record. Overall both the continental and marine climate records indicate millennial scale climate variability. Our records also shed light on shifting sources of organic matter in response to the sequential cessation and re-initiation of different tributaries to the main flow of the Nile River.

  2. Improved short-term variability in the thermosphere-ionosphere-mesosphere-electrodynamics general circulation model

    NASA Astrophysics Data System (ADS)

    Häusler, K.; Hagan, M. E.; Baumgaertner, A. J. G.; Maute, A.; Lu, G.; Doornbos, E.; Bruinsma, S.; Forbes, J. M.; Gasperini, F.

    2014-08-01

    We report on a new source of tidal variability in the National Center for Atmospheric Research thermosphere-ionosphere-mesosphere-electrodynamics general circulation model (TIME-GCM). Lower boundary forcing of the TIME-GCM for a simulation of November-December 2009 based on 3-hourly Modern-Era Retrospective Analysis for Research and Application (MERRA) reanalysis data includes day-to-day variations in both diurnal and semidiurnal tides of tropospheric origin. Comparison with TIME-GCM results from a heretofore standard simulation that includes climatological tropospheric tides from the global-scale wave model reveal evidence of the impacts of MERRA for