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Sample records for day-to-day temperature variability

  1. Vertical and interhemispheric links in the stratosphere-mesosphere as revealed by the day-to-day variability of Aura-MLS temperature data

    NASA Astrophysics Data System (ADS)

    Xu, X.; Manson, A. H.; Meek, C. E.; Chshyolkova, T.; Drummond, J. R.; Hall, C. M.; Riggin, D. M.; Hibbins, R. E.

    2009-09-01

    The coupling processes in the middle atmosphere have been a subject of intense research activity because of their effects on atmospheric circulation, structure, variability, and the distribution of chemical constituents. In this study, the day-to-day variability of Aura-MLS (Microwave Limb Sounder) temperature data are used to reveal the vertical and interhemispheric coupling processes in the stratosphere-mesosphere during four Northern Hemisphere winters (2004/2005-2007/2008). The UKMO (United Kingdom Meteorological Office) assimilated data and mesospheric winds from MF (medium frequency) radars are also applied to help highlight the coupling processes. In this study, a clear vertical link can be seen between the stratosphere and mesosphere during winter months. The coolings and reversals of northward meridional winds in the polar winter mesosphere are often observed in relation to warming events (Sudden Stratospheric Warming, SSW for short) and the associated changes in zonal winds in the polar winter stratosphere. An upper-mesospheric cooling usually precedes the beginning of the warming in the stratosphere by 1-2 days. Inter-hemispheric coupling has been identified initially by a correlation analysis using the year-to-year monthly zonal mean temperature. Then the correlation analyses are performed based upon the daily zonal mean temperature. From the original time sequences, significant positive (negative) correlations are generally found between zonal mean temperatures at the Antarctic summer mesopause and in the Arctic winter stratosphere (mesosphere) during northern mid-winters, although these correlations are dominated by the low frequency variability (i.e. the seasonal trend). Using the short-term oscillations (less than 15 days), the statistical result, by looking for the largest magnitude of correlation within a range of time-lags (0 to 10 days; positive lags mean that the Antarctic summer mesopause is lagging), indicates that the temporal variability of zonal mean temperature at the Antarctic summer mesopause is also positively (negatively) correlated with the polar winter stratosphere (mesosphere) during three (2004/2005, 2005/2006, and 2007/2008) out of the four winters. The highest value of the correlation coefficient is over 0.7 in the winter-stratosphere for the three winters. The remaining winter (2006/2007) has more complex correlations structures; correspondingly the polar vortex was distinguished this winter. The time-lags obtained for 2004/2005 and 2006/2007 are distinct from 2005/2006 and 2007/2008 where a 6-day lag dominates for the coupling between the winter stratosphere and the summer mesopause. The correlations are also provided using temperatures in northern longitudinal sectors in a comparison with the Antarctic-mesopause zonal mean temperature. For northern mid-high latitudes (~50-70 N), temperatures in Scandinavia-Eastern Europe and in the Pacific-Western Canada longitudinal sectors often have opposite signs of correlations with zonal mean temperatures near the Antarctic summer mesopause during northern mid-winters. The statistical results are shown to be associated with the Northern Hemisphere's polar vortex characteristics.

  2. The observed day-to-day variability of Mars water vapor

    NASA Technical Reports Server (NTRS)

    Jakosky, Bruce M.; Lapointe, Michael R.; Zurek, Richard W.

    1987-01-01

    The diurnal variability of atmospheric water vapor as derived from the Viking MAWD data is discussed. The detection of day to day variability of atmospheric water would be a significant finding since it would place constraints on the nature of surface reservoirs. Unfortunately, the diurnal variability seen by the MAWD experiment is well correlated with the occurrence of dust and/or ice hazes, making it difficult to separate real variations from observational effects. Analysis of the day to day variability of water vapor in the Martian atmosphere suggests that the observations are, at certain locations and seasons, significantly affected by the presence of water-ice hazes. Because such effects are generally limited to specific locations, such as Tharsis, Lunae Planum, and the polar cap edge during the spring, the seasonal and latitudinal trends in water vapor that have been previously reported are not significantly affected.

  3. Day-to-day variability of oscillatory impedance and spirometry in asthma and COPD.

    PubMed

    Timmins, Sophie C; Coatsworth, Nicholas; Palnitkar, Gaurie; Thamrin, Cindy; Farrow, Catherine E; Schoeffel, Robin E; Berend, Norbert; Diba, Chantale; Salome, Cheryl M; King, Gregory G

    2013-01-15

    Variability in airway function may be a marker of disease activity in COPD and asthma. The aim was to determine the effects of repeatability and airway obstruction on day-to-day variability in respiratory system resistance (Rrs) and reactance (Xrs) measured by forced oscillation technique (FOT). Three groups of 10 subjects; normals, stable asthmatic and stable COPD subjects underwent daily FOT recordings for 7 days. Mean total and inspiratory Rrs and Xrs, and expiratory flow limitation (EFL) Index (inspiratory - expiratory Xrs), were calculated. The ICC's were high for all parameters in all groups. Repeatability, in terms of absolute units, correlated with airway obstruction and was therefore lowest in COPD. Day-to-day variability was due mostly to repeatability, with a small contribution from the mean value for some parameters. FOT measures are highly repeatable in health, stable asthma and COPD in relation to the wide range of measures between subjects. For home monitoring in asthma and COPD, either the coefficient of variation or individualized SDs could be used to define day-to-day variability. PMID:22960661

  4. REPRODUCIBILITY OF BLOOD PRESSURE DIPPING: RELATION TO DAY-TO-DAY VARIABILITY IN SLEEP QUALITY

    PubMed Central

    Hinderliter, Alan L.; Routledge, Faye S.; Blumenthal, James A.; Koch, Gary; Hussey, Michael A.; Wohlgemuth, William K.; Sherwood, Andrew

    2013-01-01

    Background Previous studies of the reproducibility of blood pressure (BP) dipping have yielded inconsistent results. Few have examined factors that may influence dayto-day differences in dipping. Methods and Results Ambulatory BP monitoring was performed on three occasions, approximately one week apart, in 115 untreated adult subjects with elevated clinic BPs. The mean±SD BP dip was 18±7/15±5 mmHg (sleep/awake BP ratio = 0.87±0.05/0.82±0.06), with a median (interquartile range) day-to-day variation of 5.2 (3.1–8.1)/4.3(2.8–5.6) mmHg. There was no decrease in variability with successive measurements. The reproducibility coefficient (5.6 [95% CI 5.1, 6.1] mmHg) was greater and the intraclass correlation coefficient (0.53 [95% CI 0.42, 0.63]) was smaller for the systolic dip than for 24-hour or awake systolic BPs, suggesting greater day-today variability in dipping. Variability in systolic dipping was greater in subjects with higher awake BP, but was not related to age, gender, race, or body mass index. Within individuals, day-to-day variations in dipping were related to variations in the fragmentation index (p < 0.001), a measure of sleep quality. Conclusions Although mean 24-hour and awake BPs were relatively stable over repeated monitoring days, our study confirms substantial variability in BP dipping. Day-to-day differences in dipping are related to sleep quality. PMID:23850195

  5. Day-to-day variability of the global post-sunset equatorial ionization anomaly

    NASA Astrophysics Data System (ADS)

    Coker, Clayton; Dymond, Kenneth; Budzien, Scott; Chua, Damien

    We report global observations of the daily variability of the post-sunset Equatorial Ionization Anomaly (EIA). Multiple Tiny Ionospheric Photometer (TIP) sensors on the Constellation Ob-serving System for Meteorology, Ionosphere, and Climate (COSMIC) constellation are used to produce high resolution maps the global pattern of the post-sunset equatorial anomaly for indi-vidual days. TIP is a compact, nadir directed, ultraviolet photometer operating at the 135.6-nm wavelength. TIP measures the horizontal structure of the ionosphere with 15-30 km resolution and high sensitivity. For the near solar minimum condition and equinox period of Septem-ber 2006, evidence of tidal influences is observed in the equatorial anomaly. The day-to-day persistence of the 4-cell pattern produced by the diurnal eastward zonal wavenumber-3 (DE3) tide is remarkable. The daily 4-cell patterns display more dramatic variation in the equatorial anomaly than indicated by earlier studies using multi-day averages. In some longitude sectors the anomaly disappears completely on some days. The crest width is also much narrower than indicated by multi-day averages of the 4-cell pattern. Additionally, daily variations in magni-tude of individual cells are observed and appear to occur on hemispheric scales, suggesting a large scale day-to-day variability in the global neutral wind pattern. Finally, the impact of this daily variability on low latitude irregularity development and scintillation is examined.

  6. Reliability and variability of day-to-day vault training measures in artistic gymnastics.

    PubMed

    Bradshaw, Elizabeth; Hume, Patria; Calton, Mark; Aisbett, Brad

    2010-06-01

    Inter-day training reliability and variability in artistic gymnastics vaulting was determined using a customised infra-red timing gate and contact mat timing system. Thirteen Australian high performance gymnasts (eight males and five females) aged 11-23 years were assessed during two consecutive days of normal training. Each gymnast completed a number of vault repetitions per daily session. Inter-day variability of vault run-up velocities (at -18 to -12 m, -12 to -6 m, -6 to -2 m, and -2 to 0 m from the nearest edge of the beat board), and board contact, pre-flight, and table contact times were determined using mixed modelling statistics to account for random (within-subject variability) and fixed effects (gender, number of subjects, number of trials). The difference in the mean (Mdiff) and Cohen's effect sizes for reliability assessment and intra-class correlation coefficients, and the coefficient of variation percentage (CV%) were calculated for variability assessment. Approach velocity (-18 to -2m, CV = 2.4-7.8%) and board contact time (CV = 3.5%) were less variable measures when accounting for day-to-day performance differences, than pre-flight time (CV = 17.7%) and table contact time (CV = 20.5%). While pre-flight and table contact times are relevant training measures, approach velocity and board contact time are more reliable when quantifying vaulting performance. PMID:20806844

  7. Uncovering physical processes responsible for the asymmetry of day-to-day temperature changes

    NASA Astrophysics Data System (ADS)

    Huth, Radan; Piskala, Vladimir

    2015-04-01

    Day-to-day temperature changes, and especially those of minimum temperature in winter and maximum temperature in summer, are asymmetrical: in winter, large warmings occur more frequently than large coolings and small coolings occur more frequently than small warmings. In summer, the opposite is the case. We investigate causes of this asymmetry for Prague, Czech Republic. First, we relate strong temperature changes to passages of atmospheric fronts. More specifically, large warmings in winter are related with passages of warm fronts and large coolings in summer are related with passages of cold fronts. In particular, we test the hypothesis that the days with large temperature changes (changes exceeding 3°C or 5°C) are accompanied with passages of corresponding atmospheric fronts more frequently than other days. We prove statistical significance of such a relationship between front passages and large temperature changes by means of a two-sample Kolmogorov-Smirnov test. Second, we demonstrate that small temperature changes (by up to 2°C), namely, small warmings in summer and small coolings in winter, are tightly related to anticyclonic circulation conditions and, hence, occur due to radiative processes. This relationship is investigated by comparing frequencies of anticyclonic circulation types in selected classifications from the COST733 database between the days with small temperature changes and all other days. The relationship appears to be highly statistically significant. Although the findings may seem a bit trivial, we are not aware of any study that would examine and prove the relationships between front passages and anticyclonic circulation conditions on one side, and the asymmetry of day-to-day temperature changes on the other side.

  8. Role of gravity wave seed perturbations in ESF day-to-day variability: A quantitative approach

    NASA Astrophysics Data System (ADS)

    Manju, G.; Madhav Haridas, M. K.; Aswathy, R. P.

    2016-02-01

    The role of seed perturbations in the day-to-day variability of occurrence of Equatorial Spread F (ESF) is studied using Ionosonde data for years 2005-2007 at magnetic equatorial location Trivandrum (8.5°N, 77°E, and dip 1.3°N). In this paper, we present the novel result that, the amplitude of the seed perturbations, is a very critical parameter which decides, whether or not ESF would occur on a given day and that, this threshold level of seed perturbation amplitude required on a given day decreases as the post sunset height of the F layer increases. Further, the requisite seed perturbation at a particular altitude shows solar activity dependence with progressively lower requisite seeds being observed at lower levels of solar activity. Moreover, the requisite seed is also found to be showing unique altitudinal dependence for each season. These results underline the need to evolve a new ESF prediction parameter, which takes into account the amplitude of the seed perturbation along with the layer height.

  9. Day-to-day variability in cardiorespiratory responses to hypoxic cycle exercise.

    PubMed

    MacNutt, Meaghan J; Peters, Carli M; Chan, Catherine; Moore, Jason; Shum, Serena; Sheel, A William

    2015-02-01

    Repeatedly performing exercise in hypoxia could elicit an independent training response and become an unintended co-intervention. The primary purposes of this study were to determine if hypoxic exercise responses changed across repeated testing and to assess the day-to-day variability of commonly used measures of cardiorespiratory and metabolic responses to hypoxic exercise. Healthy young males (aged 23 ± 2 years) with a maximal O2 consumption of 50.7 ± 4.7 mL·kg(-1)·min(-1) performed 5 trials (H1 to H5) over a 2-week period in hypoxia (fraction of inspired oxygen = 0.13). Participants completed 3-min stages at 20%, 40%, 60%, and 10% of individual peak power. With increasing cycle exercise intensity there were increases in minute ventilation, O2 consumption, CO2 production, respiratory exchange ratio, heart rate (HR), blood lactate concentration, and ratings of perceived exertion for legs and respiratory system along with a reduction in oxyhaemoglobin saturation (%SpO2) (all p < 0.001). There were no systematic changes from H1 to H5 (p > 0.05). Most measures were highly repeatable across testing sessions with the coefficient of variation (CV) averaging ≤10% of the mean value in all variables except O2 consumption (17%), CO2 production (11%) and blood lactate concentration (17%). For HR and %SpO2 the CV was <5%. The exercise protocol did not elicit a training response when repeated 5 times during a 2-week period and the variability of exercise responses was low. We conclude that this protocol allows detection of small changes in cardiorespiratory responses to hypoxic exercise that might occur during exposure to hypoxia. PMID:25603431

  10. The day-to-day variability in ionospheric electric fields and currents

    NASA Technical Reports Server (NTRS)

    Kirchhoff, V. W. J. H.; Carpenter, L. A.

    1976-01-01

    The daily variations in ionospheric drift velocities are examined from incoherent scatter measurements at Millstone Hill. The data with summed Kp greater than 24 behave differently from those with low magnetic activity and basically follow the convection pattern but have large day-to-day variations. The influence of the magnetic conjugate point is discussed, and solar cycle variations are examined in conjunction with geomagnetic variations. Ionospheric currents calculated by using a semidiurnal neutral wind model are in good agreement with ground-based magnetograms for low magnetic activity, but the E region neutral wind model appears to be applicable only to this case.

  11. Application of data assimilation in the Whole Atmosphere Community Climate Model to the study of day-to-day variability in the middle and upper atmosphere

    NASA Astrophysics Data System (ADS)

    Pedatella, N. M.; Raeder, K.; Anderson, J. L.; Liu, H.-L.

    2013-08-01

    The Data Assimilation Research Testbed (DART) ensemble adjustment Kalman filter (EAKF) is employed to perform data assimilation in the Whole Atmosphere Community Climate Model (WACCM). To demonstrate the potential of the WACCM+DART for studying short-term variability in the mesosphere and lower thermosphere (MLT), results are presented based on the assimilation of synthetic observations that are sampled from a known model truth. We assimilate temperature and wind from radiosondes and aircraft, satellite drift winds, and COSMIC refractivity in the lower atmosphere, and SABER temperature observations in the middle/upper atmosphere. Relative to an unconstrained WACCM simulation, the assimilation of only lower atmosphere observations reduces the global root mean square error (RMSE) in zonal wind by up to 40% at MLT altitudes. Using data assimilation to constrain the lower atmosphere can therefore provide significant insight into MLT variability. The RMSE in the MLT is reduced by an additional 10-15% when SABER observations are also assimilated. The WACCM+DART is shown to be able to reproduce the large-scale features of the day-to-day variability in the zonal mean, migrating, and nonmigrating tides in the MLT. Though our simulation results are based on idealized conditions, they demonstrate that the WACCM+DART can reproduce the day-to-day variability in the MLT. Assimilation of real observations in the WACCM+DART will therefore enable significant insight into the real day-to-day dynamical variability from the surface to the lower thermosphere.

  12. Day to day variability in fat oxidation and the effect after only 1 day of change in diet composition.

    PubMed

    Støa, Eva Maria; Nyhus, Lill-Katrin; Børresen, Sandra Claveau; Nygaard, Caroline; Hovet, Åse Marie; Bratland-Sanda, Solfrid; Helgerud, Jan; Støren, Øyvind

    2016-04-01

    Indirect calorimetry is a common and noninvasive method to estimate rate of fat oxidation (FatOx) during exercise, and test-retest reliability should be considered when interpreting results. Diet also has an impact on FatOx. The aim of the present study was to investigate day to day variations in FatOx during moderate exercise given the same diet and 2 different isoenergetic diets. Nine healthy, moderately-trained females participated in the study. They performed 1 maximal oxygen uptake test and 4 FatOx tests. Habitual diets were recorded and repeated to assess day to day variability in FatOx. FatOx was also measured after 1 day of fat-rich (26.8% carbohydrates (CHO), 23.2% protein, 47.1% fat) and 1 day of CHO-rich diet (62.6% CHO, 20.1% protein, 12.4% fat). The reliability test revealed no differences in FatOx, respiratory exchange ratio (RER), oxygen uptake, carbon dioxide production, heart rate, blood lactate concentration, or blood glucose between the 2 habitual diet days. FatOx decreased after the CHO-rich diet compared with the habitual day 2 (from 0.42 ± 0.15 to 0.29 ± 0.13 g·min(-1), p < 0.05). No difference was found in FatOx between fat-rich diet and the 2 habitual diet days. FatOx was 31% lower (from 0.42 ± 0.14 to 0.29 ± 0.13 g·min(-1), p < 0.01) after the CHO-rich diet compared with the fat-rich diet. Using RER data to measure FatOx is a reliable method as long as the diet is strictly controlled. However, even a 1-day change in macronutrient composition will likely affect the FatOx results. PMID:26960444

  13. Using robust principal component analysis to alleviate day-to-day variability in EEG based emotion classification.

    PubMed

    Ping-Keng Jao; Yuan-Pin Lin; Yi-Hsuan Yang; Tzyy-Ping Jung

    2015-08-01

    An emerging challenge for emotion classification using electroencephalography (EEG) is how to effectively alleviate day-to-day variability in raw data. This study employed the robust principal component analysis (RPCA) to address the problem with a posed hypothesis that background or emotion-irrelevant EEG perturbations lead to certain variability across days and somehow submerge emotion-related EEG dynamics. The empirical results of this study evidently validated our hypothesis and demonstrated the RPCA's feasibility through the analysis of a five-day dataset of 12 subjects. The RPCA allowed tackling the sparse emotion-relevant EEG dynamics from the accompanied background perturbations across days. Sequentially, leveraging the RPCA-purified EEG trials from more days appeared to improve the emotion-classification performance steadily, which was not found in the case using the raw EEG features. Therefore, incorporating the RPCA with existing emotion-aware machine-learning frameworks on a longitudinal dataset of each individual may shed light on the development of a robust affective brain-computer interface (ABCI) that can alleviate ecological inter-day variability. PMID:26736326

  14. Day-to-day variability of equatorial electrojet and its role on the day-to-day characteristics of the equatorial ionization anomaly over the Indian and Brazilian sectors

    NASA Astrophysics Data System (ADS)

    Venkatesh, K.; Fagundes, P. R.; Prasad, D. S. V. V. D.; Denardini, C. M.; Abreu, A. J.; Jesus, R.; Gende, M.

    2015-10-01

    The equatorial electrojet (EEJ) is a narrow band of current flowing eastward at the ionospheric E region altitudes along the dayside dip equator. Mutually perpendicular electric and magnetic fields over the equator results in the formation of equatorial ionization anomaly (EIA), which in turn generates large electron density variabilities. Simultaneous study on the characteristics of EEJ and EIA is necessary to understand the role of EEJ on the EIA variabilities. This is helpful for the improved estimation of total electron content (TEC) and range delays required for satellite-based communication and navigation applications. Present study reports simultaneous variations of EEJ and GPS-TEC over Indian and Brazilian sectors to understand the role of EEJ on the day-to-day characteristics of the EIA. Magnetometer measurements during the low solar activity year 2004 are used to derive the EEJ values over the two different sectors. The characteristics of EIA are studied using two different chains of GPS receivers along the common meridian of 77°E (India) and 45°W (Brazil). The diurnal, seasonal, and day-to-day variations of EEJ and TEC are described simultaneously. Variations of EIA during different seasons are presented along with the variations of the EEJ in the two hemispheres. The role of EEJ variations on the characteristic features of the EIA such as the strength and temporal extent of the EIA crest has also been reported. Further, the time delay between the occurrences of the day maximum EEJ and the well-developed EIA is studied and corresponding results are presented in this paper.

  15. 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.

  16. Spatial versus Day-To-Day Within-Lake Variability in Tropical Floodplain Lake CH4 Emissions – Developing Optimized Approaches to Representative Flux Measurements

    PubMed Central

    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

  17. 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.

  18. Development of an Experimental Model to Study the Relationship Between Day-to-Day Variability in Blood Pressure and Aortic Stiffness

    PubMed Central

    Bouissou-Schurtz, Camille; Lindesay, Georges; Regnault, Véronique; Renet, Sophie; Safar, Michel E.; Molinie, Vincent; Dabire, Hubert; Bezie, Yvonnick

    2015-01-01

    We aimed to develop an animal model of long-term blood pressure variability (BPV) and to investigate its consequences on aortic damage. We hypothesized that day-to-day BPV produced by discontinuous treatment of spontaneously hypertensive rats (SHR) by valsartan may increase arterial stiffness. For that purpose, rats were discontinuously treated, 2 days a week, or continuously treated by valsartan (30 mg/kg/d in chow) or placebo. Telemetered BP was recorded during 2 min every 15 min, 3 days a week during 8 weeks to cover the full BP variations in response to the treatment schedule. Pulse wave velocity (PWV) and aortic structure evaluated by immunohistochemistry were investigated in a second set of rats treated under the same conditions. Continuous treatment with valsartan reduced systolic BP (SBP) and reversed the aortic structural alterations observed in placebo treated SHR (decrease of medial cross-sectional area). Discontinuous treatment with valsartan decreased SBP to a similar extent but increased the day-to-day BPV, short term BPV, diastolic blood pressure (DBP), and PWV as compared with continuous treatment. Despite no modifications in the elastin/collagen ratio and aortic thickness, an increase in PWV was observed following discontinuous treatment and was associated with a specific accumulation of fibronectin and its αv-integrin receptor compared with both groups of rats. Taken together the present results indicate that a discontinuous treatment with valsartan is able to induce a significant increase in day-to-day BPV coupled to an aortic phenotype close to that observed in hypertension. This experimental model should pave the way for future experimental and clinical studies aimed at assessing how long-term BPV increases aortic stiffness. PMID:26696902

  19. Day-to-Day Variability of H Component of Geomagnetic Field in Central African Sector Provided by YACM (Yaoundé-Cameroon) Amber Magnetometer Station

    NASA Astrophysics Data System (ADS)

    Etoundi Messanga, Honoré

    2015-04-01

    The geomagnetic data obtained from Amber Network station in Cameroon has been used for this study. The variability of H component of geomagnetic field has been examined by using geomagnetic field data of X and Y components recorded at AMBER magnetometer station hosted by the Department of Physics of University of Yaoundé (3.87°N, 11.52°E). The day-to-day variability of the horizontal intensity of the geomagnetic field has been examined and shows that the scattering of H component of magnetic field variation is more on disturbed than on quiet days. The signatures H of geomagnetic Sq and Sd variations in intensities in the geomagnetic element, has been studied. This paper shows that the daytime variations in intensities of geomagnetic elements H, Sq(H) and Sd(H) respectively are generally greater at diurnal-times than at night-times. This study mainly interests to answer to two questions: 1) how can geomagnetic variations be used to study the equatorial ionosphere electrodynamics and electrojet equatorial over Africa in general and Cameroon in particular? 2) How can geomagnetic variations be used to monitor and predict Space weather events in Cameroon? This study presents and interprets the results of H component of geomagnetic field variations during magnetic storms and on quiet days.

  20. Day-to-day variability of VTEC and ROTI in October 2012 with impact of high-speed solar wind stream on 13 October 2012

    NASA Astrophysics Data System (ADS)

    Azzouzi, I.; Migoya-Orue, Y. O.; Coisson, P.; Amory Mazaudier, C.; Fleury, R.; Radicella, S. M.

    2016-03-01

    This paper presents the day-to-day variability of the Vertical Total Electron Content (VTEC) and the Rate of change of TEC Index (ROTI) in October 2012. We focused our attention to the impact of a high-speed solar wind stream (HSSWS) on the ionosphere in middle and low latitudes on 13 October 2012. This event was preceded by two other disturbances caused by a Coronal Mass Ejection (CME) at 05:26UT on 8 October and a HSSWS around 19:00UT on 9 October. The changes in the VTEC observed during the period between 8 and 12 October preceding the 13 October case showed a comparable response of the ionosphere in both hemispheres, varying mainly with latitude and presenting a stronger impact in the Northern hemisphere. The VTEC increased at the arrival of the CME on 8 October, then decreased, and increased again on 13 October. The solar wind speed associated with the second HSSWS reached its peak, 580 km/s around 17:00UT during the recovery phase of a geomagnetic storm started around 00:00UT on 13 October. Its impact was observed in Africa and in Eastern South America on the ROTI, an indicator of ionospheric scintillation. On 13 October, the ROTI was small over whole Africa and in Eastern South America at the moment the impact of the second HSSWS. These observations are interpreted as due to the ionospheric disturbance dynamo electric field associated with the Joule heating produced in the auroral zone by the HSSWS.

  1. Coherent and incoherent scatter radar study of the climatology and day-to-day variability of mean F region vertical drifts and equatorial spread F

    NASA Astrophysics Data System (ADS)

    Smith, J. M.; Rodrigues, F. S.; Fejer, B. G.; Milla, M. A.

    2016-02-01

    We conducted a comprehensive analysis of the vertical drifts and equatorial spread F (ESF) measurements made by the Jicamarca incoherent scatter radar (ISR) between 1994 and 2013. The ISR measurements allowed us to construct not only updated climatological curves of quiet-time vertical plasma drifts but also time-versus-height maps of ESF occurrence over the past two solar cycles. These curves and maps allowed us to better relate the observed ESF occurrence patterns to features in the vertical drift curves than previously possible. We identified an excessively high occurrence of post-midnight F region irregularities during December solstice and low solar flux conditions. More importantly, we also found a high occurrence of ESF events during sudden stratospheric warming (SSW) events. We also proposed and evaluated metrics of evening enhancement of the vertical drifts and ESF occurrence, which allowed us to quantify the relationship between evening drifts and ESF development. Based on a day-to-day analysis of these metrics, we offer estimates of the minimum pre-reversal enhancement (PRE) peak (and mean PRE) values observed prior to ESF development for different solar flux and seasonal conditions. We also found that ESF irregularities can reach the altitudes at least as high as 800 km at the magnetic equator even during low solar flux conditions.

  2. An Attempt to Establish a Statistical Model of the Day-to-Day Variability of the N(sub m)F2 and h(sub m)F2 Parameters Computed from IRI

    NASA Technical Reports Server (NTRS)

    Brunini, Claudio; Azpilicueta, Francisco; Janches, Diego

    2014-01-01

    In this work we explore the possibility of using COSMIC/FORMOSAT-3 radio occultation profiles (ROP) to establish a statistical model of the deviations that can be expected between the monthly median values of N(sub m)F2 and h(sub m)F2 computed with the International Reference Ionosphere (IRI) and the actual values of these parameters. The actual values are retrieved from the ROP after an interactively re-weighted Least Square fit that, complemented with a statistical test, allows filtering of unreliable data and estimating the errors of the retrieved values. The differences between the retrieved values and the monthly median values computed from IRI are interpreted as the superposition of a systematic bias (attributed to both, IRI and ROP), random errors in ROP, and the day-to-day variability, which is unaccounted for by IRI. This variability is described with a five-dimensional function that depends on: the month, the solar activity, the geomagnetic conditions, the modip latitude, and the local time. Empirical values of this function are estimated in the form of regular grids. Since this research is restricted to low solar activity and quiet geomagnetic conditions, the grid is reduced from five to three dimensions: month, local time, and modip (modified dip latitude). We found that the standard deviation of the day-to-day variability varies according to (in percent of the monthly median value computed with IRI): (i) N(sub m)F2 at noontime: +/-10% to +/-30% with maxima over the northern and southern peaks of the Equatorial Anomaly; (ii) N(sub m)F2 at midnight: +/-20% to +/-45%, with the greatest values in the equatorial region during the months of May and September; (iii) h(sub m)F2 at noontime: +/-2% to +/-10% with minima over the modip equator; and (iv) h(sub m)F2 at midnight: +/-3% to +/-11% with the greatest values in the equatorial region from January to May and from September to January.

  3. Encapsulated radiophosphorescent standards for day-to-day photometer calibration.

    PubMed

    O'Kane, D J; Lee, J

    1990-10-01

    Solid, unquenched, radiophosphorescent standards for use in the day-to-day calibration of bottom viewing photometers (luminometers) were prepared by encapsulating commercially-available phosphor powders that are excited to phosphoresce by the beta- decay of 63Ni (t0.5 = 96 yr) or 14C (t0.5 = 5730 yr). The radionuclides are physically adsorbed on the phosphors by precipitation either as a "basic nickel carbonate" or as barium carbonate. The radioactive phosphors are then deposited by centrifugation as a thin layer at the bottom of the vials or tubes that are normally used in the photometer. The phosphor layer is infiltrated with a plastic resin and embedded. A light absorbing layer is subsequently cast over the phosphor layer to prevent stray light excitation of phosphorescence. The encapsulated photometer standards have remained mechanically and photometrically stable since their fabrication, which in some cases is 3 years ago. An equivalent level of visible luminescence emitted from the standards of up to 2.3 x 10(10) photons.s-1 was achieved by using an appropriate amount of radioactivity and the proper phosphor. The phosphor used in the standards could be chosen such that the radiophosphorescence emission spectrum corresponded approximately to the chemiluminescence or bioluminescence spectrum under investigation. PMID:2089419

  4. Macrocognition in Day-To-Day Police Incident Response

    PubMed Central

    Baber, Chris; McMaster, Richard

    2016-01-01

    Using examples of incidents that UK Police Forces deal with on a day-to-day basis, we explore the macrocognition of incident response. Central to our analysis is the idea that information relating to an incident is translated from negotiated to structured and actionable meaning, in terms of the Community of Practice of the personnel involved in incident response. Through participant observation of, and interviews with, police personnel, we explore the manner in which these different types of meaning shift over the course of incident. In this way, macrocognition relates to gathering, framing, and sharing information through the collaborative sensemaking practices of those involved. This involves two cycles of macrocognition, which we see as ‘informal’ (driven by information gathering as the Community of Practice negotiates and actions meaning) and ‘formal’ (driven by the need to assign resources to the response and the need to record incident details). The examples illustrate that these cycles are often intertwined, as are the different forms of meaning, in situation-specific ways that provide adaptive response to the demands of the incident. PMID:27014117

  5. 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 (1σ) 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 1σ 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.

  6. Association between internalizing disorders and day-to-day activities of low energetic expenditure.

    PubMed

    Gosmann, Natan Pereira; Salum, Giovanni Abrahão; Schuch, Felipe; Silveira, Patrícia Pelufo; Bosa, Vera Lucia; Goldani, Marcelo Zubaran; Manfro, Gisele Gus

    2015-02-01

    The objective of this study is to compare energetic expenditure in day-to-day activities among subjects with internalizing disorders (depression and anxiety), externalizing disorders (attention deficit/hyperactivity disorder and oppositional defiant disorder) and healthy children and adolescents without any psychiatric diagnosis. One hundred and five (n = 105) students from a community sample were evaluated throughout a structured psychiatric interview and categorized into three groups: internalizing (n = 54), externalizing (n = 12) and typically developing controls (TDC, n = 39). Energetic expenditure was evaluated using 3-day physical activity record. Subjects with internalizing disorders performed activities with lower energetic expenditure as compared to those with externalizing disorders and TDC. Participants with externalizing disorders had more energetic expenditure variability. Our study suggests that internalizing disorders are associated with activities of low energetic expenditure in day-to-day activities, extending previous findings with physical exercise. These findings may further contribute to the understanding of the associated morbidity previously described in patients with internalizing disorders. PMID:24570170

  7. 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

  8. 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…

  9. 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…

  10. Preparing Students for Front-Line Management: Non-Routine Day-to-Day Decisions

    ERIC Educational Resources Information Center

    Clydesdale, Greg; Tan, John

    2009-01-01

    Purpose: This paper attempts to reduce the gap between management education and practice. It emphasises day-to-day decisions that middle and lower level managers make. The purpose is to provide an education framework embodying a flexible approach to interpretation and solution creation, suitable for situations of ambiguity and uncertainty.…

  11. Curricular Quality and Day-to-Day Learning Activities in Pre-School

    ERIC Educational Resources Information Center

    Sylva, Kathy; Taggart, Brenda; Siraj-Blatchford, Iram; Totsika, Vasiliki; Ereky-Stevens, Katharina; Gilden, Rose; Bell, Daniel

    2007-01-01

    The purpose of this paper is to show how curricular quality is related to the day-to-day activities experienced by children and the pedagogical activities of staff, both coded through systematic target-child observations. Data were drawn from the Effective Provision of Pre-School Education (EPPE) and the Researching Effective Pedagogy in the Early…

  12. Individual Day-to-Day Process of Social Anxiety in Vulnerable College Students

    ERIC Educational Resources Information Center

    Campbell, Cynthia G.; Bierman, Karen L.; Molenaar, Peter C. M.

    2016-01-01

    Transitions requiring the creation of new social networks may be challenging for individuals vulnerable to social anxiety, which may hinder successful adjustment. Using person-specific methodology, this study examined social anxiety in vulnerable university freshman away from home during their first semester of college to understand how day-to-day

  13. 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.

  14. [New forms of healthcare cooperation in day-to-day practice].

    PubMed

    Lecointre, Brigitte

    2010-12-01

    Healthcare professionals often have to show creativity in order to ensure the continuity and quality of day-to-day treatments. They are required to accompany changes in patients' needs and expectations, and they also have to overcome many obstacles. Since the introduction of new forms of cooperation, a regulatory framework exists for this collaborative work between professionals, which helps to clarify fields of responsibility. PMID:21298944

  15. High day-to-day reliability in lower leg volume measured by water displacement.

    PubMed

    Pasley, Jeffrey D; O'Connor, Patrick J

    2008-07-01

    The day-to-day reliability of lower leg volume is poorly documented. This investigation determined the day-to-day reliability of lower leg volume (soleus and gastrocnemius) measured using water displacement. Thirty young adults (15 men and 15 women) had their right lower leg volume measured by water displacement on five separate occasions. The participants performed normal activities of daily living and were measured at the same time of day after being seated for 30 min. The results revealed a high day-to-day reliability for lower leg volume. The mean percentage change in lower leg volume across days compared to day 1 ranged between 0 and 0.37%. The mean within subjects coefficient of variation in lower leg volume was 0.72% and the coefficient of variation for the entire sample across days ranged from 5.66 to 6.32%. A two way mixed model intraclass correlation (30 subjects x 5 days) showed that the lower leg volume measurement was highly reliable (ICC = 0.972). Foot and total lower leg volumes showed similarly high reliability. Water displacement offers a cost effective and reliable solution for the measurement of lower leg edema across days. PMID:18351378

  16. Day-to-Day Inconsistency in Parent Knowledge: Links with Youth Health and Parents’ Stress

    PubMed Central

    Lippold, Melissa A.; McHale, Susan M.; Davis, Kelly D.; Kossek, Ellen Ernst

    2015-01-01

    Purpose Considerable evidence documents the linkages between higher levels of parental knowledge about youth activities and positive youth outcomes. This study investigated how day-to-day inconsistency in parental knowledge of youth activities was linked to youth behavioral, psychological, and physical health as well as parents’ stress. Methods Participants were employees in the Information Technology division of a Fortune 500 company and their children (N =129, Mean age youth = 13.39 years, 55% female). Data were collected from parents and youth via separate workplace and in-home surveys as well as telephone diary surveys on 8 consecutive evenings. We assessed day-to-day inconsistency in parental knowledge across these eight calls. Results Parents differed in their knowledge from day to day almost as much as their average knowledge scores differed from those of other parents. Controlling for mean levels of knowledge, youth whose parents exhibited more knowledge inconsistency reported more physical health symptoms (e.g., colds, flu). Knowledge inconsistency was also associated with more risky behavior for girls but greater psychological well-being for older adolescents. Parents who reported more stressors also had higher knowledge inconsistency. Conclusions Assessing only average levels of parental knowledge does not fully capture how this parenting dimension is associated with youth health. Consistent knowledge may promote youth physical health and less risky behavior for girls. Yet knowledge inconsistency also may reflect normative increases in autonomy as it was positively associated with psychological well-being for older adolescents. Given the linkages between parental stress and knowledge inconsistency, parent interventions should include stress-management components. PMID:25703318

  17. 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.

  18. Living from Day to Day – Qualitative Study on Borderline Personality Disorder in Adolescence

    PubMed Central

    Spodenkiewicz, Michel; Speranza, Mario; Taïeb, Olivier; Pham-Scottez, Alexandra; Corcos, Maurice; Révah-Levy, Anne

    2013-01-01

    Objective: The purpose of this study was to assess how far identity and self-image disturbances are features of borderline personality disorder (BPD) in adolescence. Method: Face-to-face interviews were carried out with a total of 50 adolescents with BPD and 50 controls, with a median age of 16 (SD 1.1; range 13 to 18) years. Data was analysed using a qualitative methodology, interpretative phenomenological analysis (IPA). Thematic statements representative of adolescents’ lived experience were extracted from the interviews. Results: Four main themes representing the day-to-day experiences of adolescents with BPD were identified: emotional experiences characterised by the feelings of fear, sadness and pessimism; interpersonal relationships characterised by the feelings of solitude and hostility from others; a conformist self-image characterised by a feeling of normality and difficulty in projecting into time; and, a structuring of discourse characterised by discontinuity in the perception of experiences. Conclusion: This qualitative study suggests that the day-to-day experiences of adolescents with borderline personality disorder is centred on the experience of the present. Discontinuity in self-image, alongside marked dysphoric manifestations, leads to distress and hinders compliance with care. These issues are highly relevant in psychotherapy and could lead to more effective treatment of the disorder in adolescents. PMID:24223047

  19. Applicability of day-to-day variation in behavior for the automated detection of lameness in dairy cows.

    PubMed

    de Mol, R M; André, G; Bleumer, E J B; van der Werf, J T N; de Haas, Y; van Reenen, C G

    2013-06-01

    Lameness is a major problem in modern dairy husbandry and has welfare implications and other negative consequences. The behavior of dairy cows is influenced by lameness. Automated lameness detection can, among other methods, be based on day-to-day variation in animal behavior. Activity sensors that measure lying time, number of lying bouts, and other parameters were used to record behavior per cow per day. The objective of this research was to develop and validate a lameness detection model based on daily activity data. Besides the activity data, milking data and data from the computerized concentrate feeders were available as input data. Locomotion scores were available as reference data. Data from up to 100 cows collected at an experimental farm during 23 mo in 2010 and 2011 were available for model development. Behavior is cow-dependent, and therefore quadratic trend models were fitted with a dynamic linear model on-line per cow for 7 activity variables and 2 other variables (milk yield per day and concentrate leftovers per day). It is assumed that lameness develops gradually; therefore, a lameness alert was given when the linear trend in 2 or more of the 9 models differed significantly from zero in a direction that corresponded with lameness symptoms. The developed model was validated during the first 4 mo of 2012 with almost 100 cows on the same farm by generating lameness alerts each week. Performance on the model validation data set was comparable with performance on the model development data set. The overall sensitivity (percentage of detected lameness cases) was 85.5% combined with specificity (percentage of nonlame cow-days that were not alerted) of 88.8%. All variables contributed to this performance. These results indicate that automated lameness detection based on day-to-day variation in behavior is a useful tool for dairy management. PMID:23548300

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

    SciTech Connect

    Saide, Pablo E.; Peterson, David A.; de Silva, Arlindo; Anderson, Bruce; Ziemba, Luke D.; Diskin, Glenn; Sachse, Glen; Hair, Jonathan; 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.

    2015-05-16

    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.

  1. Nonlinear day-to-day traffic dynamics with driver experience delay: Modeling, stability and bifurcation analysis

    NASA Astrophysics Data System (ADS)

    Zhao, Xiaomei; Orosz, Gábor

    2014-05-01

    In day-to-day traffic assignment problems travelers’ past experiences have important impact on their cost prediction which influences their route choice and consequently the arising flow patterns in the network. Many travelers execute the same trip in every few days, not daily, which leads to time delays in the system. In this paper, we propose a nonlinear, discrete-time model with driver experience delay. The linear stability of the stochastic user equilibrium is analyzed by studying the eigenvalues of the Jacobian matrix of the system while the nonlinear oscillations arising at the bifurcations are investigated by normal form calculations, numerical continuation and simulation. The methods are demonstrated on a two-route example. By applying rigorous analysis we show that the linearly unstable parameter domain as well as the period of arising oscillations increase with the delay. Moreover, delays and nonlinearities result in an extended domain of bistability where the stochastic user equilibrium coexists with stable and unstable oscillations. This study explains the influence of initial conditions on the dynamics of transportation networks and may provide guidance for network design and management.

  2. Department deployment: integrating quality improvement into day-to-day management.

    PubMed

    Fontana, T A; Butcher, S; O'Brien, S A

    1994-01-01

    Despite the time and resources that The George Washington University Medical Center (GWUMC) put into training and forming QI teams, QI staff found that CQI was not being used to carry out critical day-to-day departmental functions. In other words, CQI didn't affect the way staff did "real work." In response, the medical center developed an approach that integrates CQI with departmental leadership, structure, culture, and work routine. With the help of a coach, willing departments at GWUMC choose from a series of 155 activities that they complete at their own pace (eg, setting departmental CQI goals, developing a departmental mission). The department deployment process moves staff through three levels of increasing sophistication and maturity with CQI methods: awareness, understanding, and bonding. It is intended to make quality a habit for staff, or a part of the organizational mind set, rather than an isolated "project." This article will describe how the department deployment approach was developed, its philosophical underpinnings, and its methodology and tools. Then, an example will illustrate how one hospital department--social work and utilization case management--successfully used this approach. PMID:10136744

  3. 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

  4. Physical activity and sleep: Day-to-day associations among individuals with and without Bipolar Disorder

    PubMed Central

    McGlinchey, Eleanor L.; Gershon, Anda; Eidelman, Polina; Kaplan, Katherine A.; Harvey, Allison G.

    2014-01-01

    Objective To evaluate the relative role of psychopathology in the relationship between physical activity and sleep, the present study investigated the day-to-day relationship between physical activity and sleep in individuals without a psychiatric disorder and individuals with bipolar disorder using a longitudinal, naturalistic design. Method Participants in two groups—a healthy group with no psychiatric illness (N=36) and an inter-episode bipolar disorder group (N=32)— were studied over a two-month period. Physical health was assessed by the SF-36. Daily subjective and objective measures of physical activity and sleep were collected. A total of 6,670 physical activity measurements and 6,548 sleep measurements were logged. Results The bipolar disorder group exhibited poorer physical health on the SF-36 and more sleep disturbance relative to the healthy group. No group differences were found in physical activity, nor in models examining the relationship between physical activity and sleep. Hierarchical linear models indicated that for every standard deviation increase in sleep disturbance (i.e., increased total wake time), there was a three percent decrease in subsequent day physical activity, in both the healthy and bipolar groups. Increased physical activity was associated with improved sleep for participants who reported greater average sleep disturbance. Conclusions The results for all participants in the study suggest that reduced physical activity and sleep difficulties may be mutually maintaining processes, particularly for individuals who suffer from poor sleep. Findings also raise the potential importance of targeting physical activity and sleep concurrently in interventions aimed at improving physical and mental health. PMID:25506392

  5. High-throughput genotyping: practical considerations concerning the day-to-day application

    NASA Astrophysics Data System (ADS)

    McIndoe, Richard A.; Bumgarner, R. E.; Welti, Russ; Hood, Leroy

    1996-04-01

    Advances in high throughput genotyping protocols over the past few years have been remarkable. Most protocols developed to increase the throughput of genotyping rely on fluorescent based technologies for data acquisition and capture. In general, the number of genotypes per day quoted for these protocols are the result of extrapolations based on ideal situations. Here we present our experience with respect to the day to day problems of high throughput genotyping. Our laboratory is currently working on several genetic mapping projects in both mouse and man. For example, we are looking at the genetic basis for susceptibility to rheumatoid arthritis in a local native American tribe as well as a mouse animal model for the same disease. The machines used to collect gel image data are two Li- Cor infrared DNA sequencers adapted for genotyping. During the evolution of these projects, we have addressed issues concerning the tracking and flow of information from the initial extraction of DNA to the calling of the genotypes. In particular, we have focused on designing methods that are efficient, cost effective and can be easily taught to the technical staff. Computer programs have been written that record gel specific information (e.g. ID information), archive data and capture genotypes in a simple point and click environment. Instrumentation was purchased to ease the repetitive nature of sample allocation, reagent disbursement and gel loading. Using this system, we can produce genotype data on 96 individuals for 20 loci (1920 genotypes) in one day. Solutions to the overall flow of information at each of these junctions are discussed.

  6. The Day-to-Day Impact of Urogenital Aging: Perspectives from Racially/Ethnically Diverse Women

    PubMed Central

    Luft, Janis; Grady, Deborah; Kuppermann, Miriam

    2009-01-01

    ABSTRACT BACKGROUND Urogenital symptoms affect up to half of women after menopause, but their impact on women’s day-to-day functioning and wellbeing is poorly understood. METHODS Postmenopausal women aged 45 to 80 years reporting urogenital dryness, soreness, itching, or pain during sex were recruited to participate in in-depth focus groups to discuss the impact of their symptoms. Focus groups were homogenous with respect to race/ethnicity and stratified by age (for White or Black women) or language (for Latina women). Transcripts of sessions were analyzed according to grounded theory. RESULTS Six focus groups were conducted, involving 44 women (16 White, 14 Black, 14 Latina). Five domains of functioning and wellbeing affected by symptoms were identified: sexual functioning, everyday activities, emotional wellbeing, body image, and interpersonal relations. For some participants, symptoms primarily affected their ability to have and enjoy sex, as well as be responsive to their partners. For others, symptoms interfered with everyday activities, such as exercising, toileting, or sleeping. Participants regarded their symptoms as a sign that they were getting old or their body was deteriorating; women also associated symptoms with a loss of womanhood or sexuality. Additionally, participants reported feeling depressed, embarrassed, and frustrated about their symptoms, and expressed reluctance to discuss them with friends, family, or health care providers. CONCLUSIONS Urogenital symptoms can have a marked impact on sexual functioning, everyday activities, emotional wellbeing, body image, and interpersonal relations after menopause. Clinicians may need to question women actively about these symptoms, as many are reluctant to seek help for this problem. PMID:19908103

  7. 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

  8. Day-to-Day Mental and Physical Health Symptoms of Older People: A Report on Health Logs.

    ERIC Educational Resources Information Center

    Brody, Elaine M.; Kleban, Morton H.

    1983-01-01

    Older people (N=132) reported details of their day-to-day mental and physical health symptoms. Pain of various types, fatigue/weakness, mental health symptoms, and worries, bothered the largest percentages of people. Different symptoms had differing effects in curtailing activities and disturbing sleep. Results underline the interrelationships…

  9. Evolution of the Variability of Surface Temperature and Vegetation Density in the Great Plains

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study focuses on how the variability of land surface temperature and vegetation density at the SGP ARM-CART site changes over episodic (day to day) and seasonal time scales using AVHRR satellite data. Four drying periods throughout the year are analyzed. Land surface temperature had an errati...

  10. Day to Day

    ERIC Educational Resources Information Center

    Jurecki, Dennis

    2006-01-01

    A clean, healthy and safe school provides students, faculty and staff with an environment conducive to learning and working. However, budget and staff reductions can lead to substandard cleaning practices and unsanitary conditions. Some school facility managers have been making the switch to a day-schedule to reduce security and energy costs, and…

  11. Day to Day

    ERIC Educational Resources Information Center

    Jurecki, Dennis

    2006-01-01

    A clean, healthy and safe school provides students, faculty and staff with an environment conducive to learning and working. However, budget and staff reductions can lead to substandard cleaning practices and unsanitary conditions. Some school facility managers have been making the switch to a day-schedule to reduce security and energy costs, and

  12. Mobile Phone-Based Unobtrusive Ecological Momentary Assessment of Day-to-Day Mood: An Explorative Study

    PubMed Central

    Ruwaard, Jeroen; Ejdys, Michal; Schrader, Niels; Sijbrandij, Marit; Riper, Heleen

    2016-01-01

    Background Ecological momentary assessment (EMA) is a useful method to tap the dynamics of psychological and behavioral phenomena in real-world contexts. However, the response burden of (self-report) EMA limits its clinical utility. Objective The aim was to explore mobile phone-based unobtrusive EMA, in which mobile phone usage logs are considered as proxy measures of clinically relevant user states and contexts. Methods This was an uncontrolled explorative pilot study. Our study consisted of 6 weeks of EMA/unobtrusive EMA data collection in a Dutch student population (N=33), followed by a regression modeling analysis. Participants self-monitored their mood on their mobile phone (EMA) with a one-dimensional mood measure (1 to 10) and a two-dimensional circumplex measure (arousal/valence, –2 to 2). Meanwhile, with participants’ consent, a mobile phone app unobtrusively collected (meta) data from six smartphone sensor logs (unobtrusive EMA: calls/short message service (SMS) text messages, screen time, application usage, accelerometer, and phone camera events). Through forward stepwise regression (FSR), we built personalized regression models from the unobtrusive EMA variables to predict day-to-day variation in EMA mood ratings. The predictive performance of these models (ie, cross-validated mean squared error and percentage of correct predictions) was compared to naive benchmark regression models (the mean model and a lag-2 history model). Results A total of 27 participants (81%) provided a mean 35.5 days (SD 3.8) of valid EMA/unobtrusive EMA data. The FSR models accurately predicted 55% to 76% of EMA mood scores. However, the predictive performance of these models was significantly inferior to that of naive benchmark models. Conclusions Mobile phone-based unobtrusive EMA is a technically feasible and potentially powerful EMA variant. The method is young and positive findings may not replicate. At present, we do not recommend the application of FSR-based mood prediction in real-world clinical settings. Further psychometric studies and more advanced data mining techniques are needed to unlock unobtrusive EMA’s true potential. PMID:27025287

  13. The day-to-day concurrence of bodily complaints and affect in patients with severe somatoform disorder.

    PubMed

    Houtveen, Jan H; Lipovsky, Myriam M; Kool, Marloes; Sorbi, Marjolijn; Bühring, Martina E F; van Broeckhuysen-Kloth, Saskia

    2015-10-01

    Based on the concept of somatization, psychological distress can be experienced as symptoms of physical illness. This suggests a close-fitting intra-individual association between bodily complaints and mood in patients with somatoform disorder (SFD). The contemporaneous day-to-day complaints-mood association was investigated in patients with severe chronic SFD using an ecological momentary assessment (EMA) design. Eleven patients, who had recently received specialized tertiary care treatment for severe chronic SFD, kept an online electronic diary for four consecutive weeks. They were prompted at intervals throughout the day to complete questions on their momentary primary symptoms (pain and fatigue), and mood state (negative and positive). For each measure, day-mean aggregated values were computed and analyzed using linear multilevel (mixed model) regression analysis. Fixed factor results showed that symptoms were associated with both negative mood state (β = 0.47) and positive mood state (β = -0.59). Random results, however, indicated large inter-individual differences, with correlations varying between 0.17 and 0.99 for negative affect, and between -0.88 and 0.14 for positive affect. A substantial day-to-day contemporaneous association between symptoms and affect across subjects, as well as large inter-individual differences in this association, were demonstrated in patients with severe chronic SFD. EMA-data showing the relationship between both negative and (inverse) positive mood and complaints has potential clinical relevance: providing SFD patients with feedback consisting of their personal day-to-day concurrency graph may promote their understanding of their own complaints in a broader context than the somatic area. PMID:26032264

  14. The day-to-day process of stopping or reducing smoking: A prospective study of self-changers

    PubMed Central

    Hughes, John R.

    2009-01-01

    Introduction Almost all descriptions of attempts to quit smoking have focused on what happens after an abrupt quit attempt and end once a smoker relapses. The current study examined the day-to-day process preceding a quit or reduction attempt in addition to the daily process after a failure to quit or reduce. Methods We recruited 220 adult daily cigarette smokers who planned to quit abruptly, to quit gradually, to reduce only, or to not change on their own. Participants called a voice mail system each night for 28 days to report cigarette use for that day and their intentions for smoking for the next day. No treatment was provided. Results Three main findings emerged: (a) The large majority of participants did not show a simple pattern of change but rather showed a pattern of multiple transitions among smoking, abstinence, and reduction over a short period of time; (b) most of those who reported an initial goal to quit abruptly actually reduced; and (c) daily intentions to quit strongly predicted abstinence, while daily intentions to reduce weakly predicted reduction. Discussion We conclude that the day-to-day process of attempts to change smoking among nontreatment seekers is much more dynamic than previously thought. This suggests that extended treatment beyond initial lapses and relapses and during postcessation reduction may be helpful. PMID:19561132

  15. 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.

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

    SciTech Connect

    Mulholland, Patrick J

    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).

  17. Associations between Relationship Status and Day-to-Day Health Behaviors and Weight among Diverse Young Adults

    PubMed Central

    Berge, Jerica M.; Bauer, Katherine W.; MacLehose, Rich; Eisenberg, Marla E.; Neumark-Sztainer, Dianne

    2014-01-01

    Introduction Previous research has shown strong positive associations between physical and psychological health outcomes and being in a committed relationship, such as marriage, however little research has investigated whether being in a committed relationship is protective for day-to-day health behaviors such as dietary patterns and physical activity. The main aim of this paper is to examine associations between relationship status and day-to-day health behaviors (e.g. dietary intake, physical activity) and weight status among a diverse cohort of young adults. Methods This cross-sectional study utilized data from Project EAT-III, a 10-year longitudinal population-based study (n = 1853) of Midwest young adults. Young adult participants had an average age of 25.3, and were 45% male and 55% female. Participants were socio economically and racially/ethnically diverse, including 48.4% white, 18.6% African American, 5.9% Hispanic, 19.6% Asian, 3.3% Native American, and 4.2% mixed or other race/ethnicity. Results Results indicated that married men were more likely to be overweight/obese (BMI ? 25) compared to single/casually dating and committed dating/engaged men. Married women were more likely to eat breakfast ? 5 times per week compared to women in other relationship categories. No differences were observed in young adults other health behaviors by relationship status. There were no significant interactions by race/ethnicity. Discussion Relationship status seems largely unrelated to young adults participation in physical activity and dietary behaviors. However, findings suggest that being married may be a risk factor for overweight/obesity in young adult men and may be a protective factor for other health-related behaviors associated with overweight/obesity such as eating breakfast for young adult women. PMID:24417654

  18. Associations between relationship status and day-to-day health behaviors and weight among diverse young adults.

    PubMed

    Berge, Jerica M; Bauer, Katherine W; Maclehose, Rich; Eisenberg, Marla E; Neumark-Sztainer, Dianne

    2014-03-01

    Previous research has shown strong positive associations between physical and psychological health outcomes and being in a committed relationship, such as marriage; however, little research has investigated whether being in a committed relationship is protective for day-to-day health behaviors such as dietary patterns and physical activity. This research examined associations between relationship status and day-to-day health behaviors (e.g., dietary intake, physical activity) and weight status among a diverse cohort of young adults. This cross-sectional study used data from Project EAT-III, a 10-year longitudinal population-based study (N = 1,853) of Midwest young adults. Young adult participants had an average age of 25.3 years, and were 45% male and 55% female. Participants were socioeconomically and racially/ethnically diverse, including 48.4% White, 18.6% African American, 5.9% Hispanic, 19.6% Asian, 3.3% Native American, and 4.2% mixed or other race/ethnicity. Results indicated that married men were more likely to be overweight/obese (body mass index ≥ 25) compared with single/casually dating and committed dating/engaged men. Married women were more likely to eat breakfast ≥5 times per week compared with women in other relationship categories. No differences were observed in other health behaviors by relationship status. There were no significant interactions by race/ethnicity. Relationship status seems largely unrelated to young adults' participation in physical activity and dietary behaviors. However, findings suggest that being married may be a risk factor for overweight/obesity in young adult men and may be a protective factor for health-related behaviors associated with overweight/obesity such as breakfast intake for young adult women. PMID:24417654

  19. 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

  20. Day to Day Operations of Home School Families: Selecting from a Menu of Educational Choices to Meet Students' Individual Instructional Needs

    ERIC Educational Resources Information Center

    Anthony, Kenneth V.; Burroughs, Susie

    2012-01-01

    This study examined the day to day operations of home schools. The case study method was used with four families from a larger pool of families that held membership in a home school organization. Data was gathered using interviews, observations, and artifacts. Findings suggest that these families operated their home schools using traditional…

  1. 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.

    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)

  2. 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 = 11.62years) completed daily assessments of their academic

  3. 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…

  4. Day to day with COPD

    MedlinePlus

    ... Also call your doctor if: You need to lean forward when sitting in order to breathe easily ... Lung Disease (GOLD). Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease. Vancouver ( ...

  5. 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.

  6. Vacuum Variable Medium Temperature Blackbody

    NASA Astrophysics Data System (ADS)

    Morozova, S. P.; Parfentiev, N. A.; Lisiansky, B. E.; Melenevsky, U. A.; Gutschwager, B.; Monte, C.; Hollandt, J.

    2010-09-01

    This article describes the vacuum variable medium-temperature blackbody (VMTBB) constructed to serve as a highly stable reference source with an aperture diameter of 20 mm in the temperature range from 150 °C to 430 °C under medium-vacuum conditions (10-3 Pa) and in a reduced background environment (liquid-nitrogen-cooled shroud). The VMTBB was realized for the calibration facility at the PTB in the field of reduced background radiation thermometry under vacuum. This facility is intended for performing radiometric and radiation thermometric measurements under vacuum conditions in the temperature range from -173 °C to 430 °C and spectral emissivity measurements in the temperature range from 0 °C to 600 °C without atmospheric interferences. It is difficult to realize a precision blackbody with high emissivity for temperatures above 400 °C. Cavities of such blackbodies are normally made of copper and coated by a paint with high emissivity. But any paint put on copper does not survive several cycles of heating to temperatures up to 450 °C. As a result of investigations at PTB, a special procedure of coating the surface of the cavity by paint with high emissivity has been developed. The cavity surface is coated by chemical nickel plating before covering it by a paint with high emissivity. The general concept and the design of the VMTBB are given. For realization of good temperature uniformity along the complete radiating cavity, a three module design is used consisting of a heat exchanger and two stages of temperature control of the cavity, based on two precision PID controllers. The temperature of the cavity is determined by 15 precision Pt resistance thermometers. Six of them are used for the VMTBB cavity and heat exchanger temperature control, and the others are used for the cavity temperature measurement and correction. A description of the temperature control and measurement system of the VMTBB is presented. Optical ray tracing with a Monte Carlo method (STEEP 3) indicated that the effective emissivity of this blackbody cavity is not worse than 0.9994. Tests of the VMTBB were carried out at the PTB facility, and the radiation of the VMTBB was measured in comparison to the vacuum variable low-temperature blackbody (VLTBB) in the temperature range from 150 °C to 170 °C with the vacuum infrared standard radiation thermometer (VIRST). The temperature uniformity of the blackbody from the bottom to the front of the cavity is better than ±100 mK in the whole temperature range. The stability of the temperature of the blackbody is within 50 mK in the whole temperature range.

  7. Stereotactic Body Radiation Therapy for Liver Tumors: Impact of Daily Setup Corrections and Day-to-Day Anatomic Variations on Dose in Target and Organs at Risk

    SciTech Connect

    Mendez Romero, Alejandra; Zinkstok, Roel Th.; Wunderink, Wouter; Os, Rob M. van; Joosten, Hans; Seppenwoolde, Yvette; Nowak, Peter; Brandwijk, Rene P.; Verhoef, Cornelis; Ijzermans, Jan N.M.; Levendag, Peter C.; Heijmen, Ben J.M.

    2009-11-15

    Purpose: To assess day-to-day differences between planned and delivered target volume (TV) and organ-at-risk (OAR) dose distributions in liver stereotactic body radiation therapy (SBRT), and to investigate the dosimetric impact of setup corrections. Methods and Materials: For 14 patients previously treated with SBRT, the planning CT scan and three treatment scans (one for each fraction) were included in this study. For each treatment scan, two dose distributions were calculated: one using the planned setup for the body frame (no correction), and one using the clinically applied (corrected) setup derived from measured tumor displacements. Per scan, the two dose distributions were mutually compared, and the clinically delivered distribution was compared with planning. Doses were recalculated in equivalent 2-Gy fraction doses. Statistical analysis was performed with the linear mixed model. Results: With setup corrections, the mean loss in TV coverage relative to planning was 1.7%, compared with 6.8% without corrections. For calculated equivalent uniform doses, these figures were 2.3% and 15.5%, respectively. As for the TV, mean deviations of delivered OAR doses from planning were small (between -0.4 and +0.3 Gy), but the spread was much larger for the OARs. In contrast to the TV, the mean impact of setup corrections on realized OAR doses was close to zero, with large positive and negative exceptions. Conclusions: Daily correction of the treatment setup is required to obtain adequate TV coverage. Because of day-to-day patient anatomy changes, large deviations in OAR doses from planning did occur. On average, setup corrections had no impact on these doses. Development of new procedures for image guidance and adaptive protocols is warranted.

  8. Individual Differences and Day-to-Day Fluctuations in Perceived Self-Regulation Associated With Daily Adherence in Late Adolescents With Type 1 Diabetes

    PubMed Central

    Wiebe, Deborah J.; Suchy, Yana; Hughes, Amy E.; Anderson, Jessica H.; Godbey, Elida I.; Butner, Jonathan; Tucker, Christy; Franchow, Emilie I.; Pihlaskari, Andrea K.; King, Pamela S.; Murray, Mary A.; White, Perrin C.

    2014-01-01

    Objective To examine whether individual differences and intraindividual (within-person day-to-day) fluctuations in late adolescents’ self-regulation were associated with daily adherence to the type 1 diabetes regimen. Methods 110 school seniors (M age = 17.78 years) and their mothers assessed adolescents’ skills underlying self-regulation (executive function, attention, self-control, behavioral inhibition and activation, emotion regulation) and adherence, with glycosylated hemoglobin from medical records. Teens completed daily diaries reporting self-regulation failures surrounding monitoring blood glucose, adherence, and number of blood glucose checks each day for 14 days. Results Hierarchical Linear Models indicated that better daily adherence was associated with teen and mother reports of better self-regulation skills and teens’ reports of fewer daily self-regulation failures. Daily adherence was unrelated to temperamental differences in behavioral inhibition and activation. Conclusions Results indicate that both individual and intraindividual differences in self-regulation contribute to daily adherence highlighting the importance of daily self-regulatory challenges to adherence. PMID:25064802

  9. The Day-to-Day Impact of Vaginal Aging Questionnaire: A Multidimensional Measure of the Impact of Vaginal Symptoms on Functioning and Well-being in Postmenopausal Women

    PubMed Central

    Huang, Alison J.; Gregorich, Steven E.; Kuppermann, Miriam; Nakagawa, Sanae; Van Den Eeden, Stephen K.; Brown, Jeanette S.; Richter, Holly E.; Walter, Louise C.; Thom, David; Stewart, Anita L.

    2014-01-01

    Objective To develop a self-report questionnaire assessing the impact of vaginal dryness, soreness, itching, irritation, and pain on functioning and well-being in postmenopausal women. Methods Structured self-report items were developed to address the impact of vaginal symptoms on functioning and wellbeing based on findings from focus groups with racially/ethnically diverse, symptomatic postmenopausal women. Items were refined after cognitive interview pre-testing and then field-tested among symptomatic postmenopausal women enrolled in a multiethnic cohort study in California. Exploratory (SAS PROC VARCLUS) and confirmatory factor analyses evaluated factor structure and eliminate poorly fitting items. Additional evidence of construct validity was obtained via examination of correlations with other measures of related constructs. Internal consistency and test-re-test reliability were assessed using Cronbach’s alpha and correlation coefficients, respectively. Results Of the 745 postmenopausal women completing the draft questionnaire, mean (SD) age was 56.2 (8.5) years, and 66% were racial/ethnic minorities. The refined questionnaire included four multi-item scales addressing symptom impact on: 1) activities of daily living, 2) emotional well-being, 3) sexual functioning, and 4) self-concept and body image. The four factor model provided good approximate fit (comparative fit index = 0.987, standardized root-mean-square residual = 0.038). Correlations with other measures of symptom bothersomeness, sexual function, depression, and anxiety conformed to hypotheses. Cronbach’s alpha ranged from 0.82 to 0.93. Intra-class coefficients ranged from 0.47 to 0.72. Conclusions The Day-to-Day Impact of Vaginal Aging (DIVA) questionnaire is a new multidimensional self-report measure designed to facilitate evaluation of the impact of vaginal symptoms in postmenopausal women of diverse backgrounds. PMID:24983271

  10. 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

  11. Longitudinal Variability of Thermospheric Temperature

    NASA Astrophysics Data System (ADS)

    Shepherd, M.; Shepherd, G.; Cho, Y.-M.

    2012-04-01

    A topic of great current interest in atmospheric dynamics is the developing recognition of the influence of the diurnal eastward-propagating non-migrating tide of wavenumber 3 (DE3) on the thermosphere. Longitudinal variations of F-region ionospheric electron density show a zonal wavenumber 4 pattern, expected for satellite observations at a fixed local time with respect to a rotating Earth. WINDII observations of airglow O(1S) volume emission rate (VER), excited by photoelectron impact on atomic oxygen at 250 km were interpreted as neutral density observations; they have shown the wavenumber 4 to be a common density perturbation in the equatorial thermosphere. The analysis has been extended further by examining thermospheric neutral temperatures at 245 km height derived from the observed daytime O(1S)VERs and the atomic oxygen density scale heights centred at this altitude. The observations examined have shown a distinct wave-4 signature at 20°S-40°S for the period from September to April with a more pronounced increase during fall equinox. Another enhancement of the wave 4 amplitude is observed during January. At the same time the quasi 2-day wave was observed in the MLT region in Rayleigh scattering temperatures and up to 180 km in O(1S) airglow and wind observations. The thermospheric temperatures at 245 km are further analysed for quasi 2-day wave signatures in attempt to determine the source of the observed thermospheric temperature wave-4 perturbations and their coupling with the neutral atmosphere below.

  12. 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.

  13. Variable temperature semiconductor film deposition

    DOEpatents

    Li, Xiaonan; Sheldon, Peter

    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.

  14. Variable temperature seat climate control system

    DOEpatents

    Karunasiri, Tissa R.; Gallup, David F.; Noles, David R.; Gregory, Christian T.

    1997-05-06

    A temperature climate control system comprises a variable temperature seat, at least one heat pump, at least one heat pump temperature sensor, and a controller. Each heat pump comprises a number of Peltier thermoelectric modules for temperature conditioning the air in a main heat exchanger and a main exchanger fan for passing the conditioned air from the main exchanger to the variable temperature seat. The Peltier modules and each main fan may be manually adjusted via a control switch or a control signal. Additionally, the temperature climate control system may comprise a number of additional temperature sensors to monitor the temperature of the ambient air surrounding the occupant as well as the temperature of the conditioned air directed to the occupant. The controller is configured to automatically regulate the operation of the Peltier modules and/or each main fan according to a temperature climate control logic designed both to maximize occupant comfort during normal operation, and minimize possible equipment damage, occupant discomfort, or occupant injury in the event of a heat pump malfunction.

  15. Variable effects of temperature on insect herbivory

    PubMed Central

    Burkepile, Deron E.; Parker, John D.

    2014-01-01

    Rising temperatures can influence the top-down control of plant biomass by increasing herbivore metabolic demands. Unfortunately, we know relatively little about the effects of temperature on herbivory rates for most insect herbivores in a given community. Evolutionary history, adaptation to local environments, and dietary factors may lead to variable thermal response curves across different species. Here we characterized the effect of temperature on herbivory rates for 21 herbivore-plant pairs, encompassing 14 herbivore and 12 plant species. We show that overall consumption rates increase with temperature between 20 and 30 °C but do not increase further with increasing temperature. However, there is substantial variation in thermal responses among individual herbivore-plant pairs at the highest temperatures. Over one third of the herbivore-plant pairs showed declining consumption rates at high temperatures, while an approximately equal number showed increasing consumption rates. Such variation existed even within herbivore species, as some species exhibited idiosyncratic thermal response curves on different host plants. Thus, rising temperatures, particularly with respect to climate change, may have highly variable effects on plant-herbivore interactions and, ultimately, top-down control of plant biomass. PMID:24860701

  16. 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

  17. Middle Pliocene sea surface temperature variability

    USGS Publications Warehouse

    Dowsett, H.J.; Chandler, M.A.; Cronin, T. M.; Dwyer, G.S.

    2005-01-01

    Estimates of sea surface temperature (SST) based upon foraminifer, diatom, and ostracod assemblages from ocean cores reveal a warm phase of the Pliocene between about 3.3 and 3.0 Ma. Pollen records and plant megafossils, although not as well dated, show evidence for a warmer climate at about the same time. Increased greenhouse forcing and altered ocean heat transport are the leading candidates for the underlying cause of Pliocene global warmth. Despite being a period of global warmth, this interval encompasses considerable variability. Two new SST reconstructions are presented that are designed to provide a climatological error bar for warm peak phases of the Pliocene and to document the spatial distribution and magnitude of SST variability within the mid-Pliocene warm period. These data suggest long-term stability of low-latitude SST and document greater variability in regions of maximum warming. Copyright 2005 by the American Geophysical Union.

  18. Variability of the Martian thermospheric temperatures during the last 7 Martian Years

    NASA Astrophysics Data System (ADS)

    Gonzalez-Galindo, Francisco; Lopez-Valverde, Miguel Angel; Millour, Ehouarn; Forget, François

    2014-05-01

    The temperatures and densities in the Martian upper atmosphere have a significant influence over the different processes producing atmospheric escape. A good knowledge of the thermosphere and its variability is thus necessary in order to better understand and quantify the atmospheric loss to space and the evolution of the planet. Different global models have been used to study the seasonal and interannual variability of the Martian thermosphere, usually considering three solar scenarios (solar minimum, solar medium and solar maximum conditions) to take into account the solar cycle variability. However, the variability of the solar activity within the simulated period of time is not usually considered in these models. We have improved the description of the UV solar flux included on the General Circulation Model for Mars developed at the Laboratoire de Météorologie Dynamique (LMD-MGCM) in order to include its observed day-to-day variability. We have used the model to simulate the thermospheric variability during Martian Years 24 to 30, using realistic UV solar fluxes and dust opacities. The model predicts and interannual variability of the temperatures in the upper thermosphere that ranges from about 50 K during the aphelion to up to 150 K during perihelion. The seasonal variability of temperatures due to the eccentricity of the Martian orbit is modified by the variability of the solar flux within a given Martian year. The solar rotation cycle produces temperature oscillations of up to 30 K. We have also studied the response of the modeled thermosphere to the global dust storms in Martian Year 25 and Martian Year 28. The atmospheric dynamics are significantly modified by the global dust storms, which induces significant changes in the thermospheric temperatures. The response of the model to the presence of both global dust storms is in good agreement with previous modeling results (Medvedev et al., Journal of Geophysical Research, 2013). As expected, the simulated ionosphere is also sensitive to the variability of the solar activity. Acknowledgemnt: Francisco González-Galindo is funded by a CSIC JAE-Doc contract financed by the European Social Fund

  19. Physical characteristics of Eurasian winter temperature variability

    NASA Astrophysics Data System (ADS)

    Kim, Kwang-Yul; Son, Seok-Woo

    2016-04-01

    Despite the on-going global warming, recent winters in Eurasian mid-latitudes were much colder than average. In an attempt to better understand the physical characteristics for cold Eurasian winters, major sources of variability in surface air temperature (SAT) are investigated based on cyclostationary EOF analysis. The two leading modes of SAT variability represent the effect of Arctic amplification (AA) and the Arctic oscillation (AO), respectively. These two modes are distinct in terms of the physical characteristics, including surface energy fluxes and tropospheric circulations, and result in significantly different winter SAT patterns over the Eurasian continent. The AA-related SAT anomalies are dipolar with warm Arctic, centered at the Barents–Kara Seas, and cold East Asia. In contrast, the negative AO-related SAT anomalies are characterized by widespread cold anomalies in Northern Eurasia. Relative importance of the AA and the negative AO contributions to cold Eurasian winters is sensitive to the region of interest.

  20. Thermoelectric convection in a variable temperature field

    NASA Astrophysics Data System (ADS)

    Belyaev, A. V.; Smorodin, B. L.

    2008-03-01

    We have studied the convective instability of a horizontal layer of a liquid semiconductor or an ionic melt in the presence of a variable temperature gradient under microgravity conditions in the case where an excess charge can appear only as a result of the thermostimulated diffusion. Thresholds for the onset of thermoelectric convective instability are determined. It is established that, under variable thermal action with a zero mean value, perturbations of a subharmonic response are absent. Depending on the amplitude and frequency of modulation and on the physical properties of the semiconductor (or the melt), synchronous perturbations are differently manifested and belong to various classes. The amplitudes and frequencies of an external action necessary for the effective suppression of thermoelectric convection are determined.

  1. Forecasting neutron star temperatures: predictability and variability.

    PubMed

    Page, Dany; Reddy, Sanjay

    2013-12-13

    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 control parameters that change the fiducial crustal thermal conductivity, specific heat, and heating rates. Observations of thermal relaxation constrain these 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. PMID:24483640

  2. 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

  3. Control of radiation and evaporation on temperature variability in a WRF regional climate simulation: comparison with colocated long term ground based observations near Paris

    NASA Astrophysics Data System (ADS)

    Bastin, S.; Chiriaco, M.; Drobinski, P.

    2016-03-01

    The objective of this paper is to understand how large-scale processes, cloud cover and surface fluxes affect the temperature variability over the SIRTA site, near Paris, and in a regional climate simulation performed in the frame of HyMeX/Med-CORDEX programs. This site is located in a climatic transitional area where models usually show strong dispersions despite the significant influence of large scale on interannual variability due to its western location. At seasonal time scale, the temperature is mainly controlled by surface fluxes. In the model, the transition from radiation to soil moisture limited regime occurs earlier than in observations leading to an overestimate of summertime temperature. An overestimate of shortwave radiation (SW), consistent with a lack of low clouds, enhances the soil dryness. A simulation with a wet soil is used to better analyse the relationship between dry soil and clouds but while the wetter soil leads to colder temperature, the cloud cover during daytime is not increased due to the atmospheric stability. At shorter time scales, the control of surface radiation becomes higher. In the simulation, higher temperatures are associated with higher SW. A wet soil mitigates the effect of radiation due to modulation by evaporation. In observations, the variability of clouds and their effect on SW is stronger leading to a nearly constant mean SW when sorted by temperature quantile but a stronger impact of cloud cover on day-to-day temperature variability. Impact of cloud albedo effect on precipitation is also compared.

  4. Precision and variability in bacterial temperature sensing.

    PubMed

    Yoney, Anna; Salman, Hanna

    2015-05-19

    In Escherichia coli, the ratio of the two most abundant chemoreceptors, Tar/Tsr, has become the focus of much attention in bacterial taxis studies. This ratio has been shown to change under various growth conditions and to determine the response of the bacteria to the environment. Here, we present a study that makes a quantitative link between the ratio Tar/Tsr and the favored temperature of the cell in a temperature gradient and in various chemical environments. From the steady-state density-profile of bacteria with one dominant thermo-sensor, Tar or Tsr, we deduce the response function of each receptor to temperature changes. Using the response functions of both receptors, we determine the relationship between the favored temperature of wild-type bacteria with mixed clusters of receptors and the receptor ratio. Our model is based on the assumption that the behavior of a wild-type bacterium in a temperature gradient is determined by a linear combination of the independent responses of the two receptors, factored by the receptor's relative abundance in the bacterium. This is confirmed by comparing our model predictions with measurements of the steady-state density-profile of several bacterial populations in a temperature gradient. Our results reveal that the density-profile of wild-type bacteria can be accurately described by measuring the distribution of the ratio Tar/Tsr in the population, which is then used to divide the population into groups with distinct Tar/Tsr values, whose behavior can be described in terms of independent Gaussian distributions. Each of these Gaussians is centered about the favored temperature of the subpopulation, which is determined by the receptor ratio, and has a width defined by the temperature-dependent speed and persistence time. PMID:25992721

  5. Predation life history responses to increased temperature variability.

    PubMed

    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

  6. 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

  7. Variable Temperature Equipment for a Commercial Magnetic Susceptibility Balance

    ERIC Educational Resources Information Center

    Lotz, Albert

    2008-01-01

    Variable temperature equipment for the magnetic susceptibility balance MSB-MK1 of Sherwood Scientific, Ltd., is described. The sample temperature is controlled with streaming air heated by water in a heat exchanger. Whereas the balance as sold commercially can be used only for room temperature measurements, the setup we designed extends the…

  8. Variability of Soil Temperature: A Spatial and Temporal Analysis.

    ERIC Educational Resources Information Center

    Walsh, Stephen J.; And Others

    1991-01-01

    Discusses an analysis of the relationship of soil temperatures at 3 depths to various climatic variables along a 200-kilometer transect in west-central Oklahoma. Reports that temperature readings increased from east to west. Concludes that temperature variations were explained by a combination of spatial, temporal, and biophysical factors. (SG)

  9. Variable Temperature Equipment for a Commercial Magnetic Susceptibility Balance

    ERIC Educational Resources Information Center

    Lotz, Albert

    2008-01-01

    Variable temperature equipment for the magnetic susceptibility balance MSB-MK1 of Sherwood Scientific, Ltd., is described. The sample temperature is controlled with streaming air heated by water in a heat exchanger. Whereas the balance as sold commercially can be used only for room temperature measurements, the setup we designed extends the

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

    PubMed Central

    Wang, Kaicun; Dickinson, Robert E.

    2013-01-01

    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

  11. 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

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

    NASA Astrophysics Data System (ADS)

    Wang, Kaicun; Dickinson, Robert

    2014-05-01

    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.

  13. Understanding and predicting temperature variability in the observational record

    NASA Astrophysics Data System (ADS)

    McKinnon, Karen Aline

    Temperature variability and change over land and ocean exhibit characteristic spatial and temporal structures. Understanding the physical mechanisms underlying these structures provides information about the movement and storage of heat in the climate system. In this thesis, I first analyze, and present an energy balance model for, seasonal temperature variability in the extratropics, which supports the idea that the advection of heat between land and ocean by the mean atmospheric circulation can explain the regional characteristics of seasonal variability over both land and ocean. The model is subsequently combined with a large, representative ensemble of Lagrangian atmospheric trajectories to provide a realistic model of the seasonal cycle in the Northern Hemisphere mid-latitudes. Second, based on the Lagrangian trajectories, a new spatially-resolved metric, termed Relative Land Influence, is developed. The metric quantifies the role of land as compared to ocean in influencing the temperature variability at a given location. In addition to explaining the majority of the spatial pattern of seasonal variability, Relative Land Influence is a significant predictor of the observed temperature change over both land and ocean independently since 1950, suggesting that similar physical processes influence temperature variability on seasonal and decadal timescales. Finally, I explore the tails of temperature distributions in the context of identifying the causes of anomalously hot days in the Eastern United States during peak summer. A coupled ocean-atmosphere mode in the central mid-latitude Pacific is identified, which evolves on a characteristic timescale and ultimately leads to the amplification of a mid-latitude wave train that includes a blocking high over the Eastern United States. The early identification of the sea surface temperature precursors to this mode allows for skillful prediction of heat events at lead times greater than 40 days. The identification of physical processes underlying temperature variability on a range of timescales can inform predictions of how temperature variability may change in the future.

  14. Spatial variability of correlated color temperature of lightning channels

    NASA Astrophysics Data System (ADS)

    Shimoji, Nobuaki; Aoyama, Ryoma; Hasegawa, Wataru

    In this paper, we present the spatial variability of the correlated color temperature of lightning channel shown in a digital still image. In order to analyze the correlated color temperature, we calculated chromaticity coordinates of the lightning channels in the digital still image. From results, the spatial variation of the correlated color temperature of the lightning channel was confirmed. Moreover, the results suggest that the correlated color temperature and peak current of the lightning channels are related to each other.

  15. Variability of dayside electron temperature at Venus

    NASA Astrophysics Data System (ADS)

    Mahajan, K. K.; Ghosh, S.; Paul, R.; Hoegy, W. R.

    1994-01-01

    Langmuir probe measurements on Pioneer Venus Orbiter show that electron temperature (Te) profiles exhibit two distinct regions. The lower, but more extended region is in the main ionosphere where Te increases slowly with altitude. The other, less extended region is in the ionopause, where Te rise sharply with altitude. If horizontal magnetic fields and flux ropes in the ionosphere inhibit vertical thermal conductivity sufficiently, then the observed Te profile could be explained with EUV as the major heat source (Cravens et al., 1980). The rise in Te in the ionopause region has generally been attributed to solar wind heating (Brace and Kliore, 1991). We suggest that this sharp rise in Te is due primarily to the steep fall in electron density, Ne. If the heating rate is essentially unchanged and heat conduction is not of primary importance, then a steep rise in Te will maintain a constant electron cooling rate for a steeply falling Ne. We have observed large orbit to orbit variations in Te in the ionopause region which are found to be inversely related to changes in Ne. Variations in solar wind dynamic pressure do not seem to have a direct effect on Te, rather the effect is indirect coming through the sharp decrease in Ne.

  16. Scale of temperature variability in the maritime Antarctic intertidal zone

    NASA Astrophysics Data System (ADS)

    Kuklinski, Piotr; Balazy, Piotr

    2014-01-01

    The Antarctic Peninsula is currently considered as one of the fastest changing regions on Earth yet temperature variability in some of its environments and habitats is not well-documented. Given the increased glacier retreat, summer melts, sea level rise and ozone losses the intertidal zone is likely to be one of the most rapidly altering of environments but also one of the least investigated in polar waters. This study aims to quantify summer temperature variability in some habitats of the intertidal zone at King George Island. Three transects were selected across tidal flat. Four temperature loggers were deployed at each of them from extreme low water spring tide level to extreme high water spring tide level between 07.12.2010 and 18.03.2011. All the loggers were deployed at the rocky substratum. The temperature range across the study tidal flat was between - 2.26 °C and + 21.18 °C. The average (summer) temperature obtained from 12 loggers varied from + 1.89 to + 3.26 °C. In all the three transects average temperature increased with tidal height. Much higher temperature variability was recorded at higher than at lower tide locations. Differences in temperature between the three study transects existed. Results obtained from the studied tidal flat show that several factors combined altogether, including: water movement by tidal forces, wave action, air temperature, sun light intensity, shore lithology and the presence of ice and snow in the area, seem to influence its temperature.

  17. On the variability of seasonal temperature in southern South America

    NASA Astrophysics Data System (ADS)

    Berman, Ana Laura; Silvestri, Gabriel; Compagnucci, Rosa

    2013-04-01

    The aim of this paper is to investigate different aspects of the seasonal-to-interannual temperature variability in Eastern Patagonia, the southernmost area of South America, east of the Andes Cordillera. Homogenous regions of seasonal variability and the atmospheric circulation patterns associated with warm and cold conditions in each of them are described in this study. Relationships between temperature in Eastern Patagonia and that registered in other areas of southern South America are also addressed. Results show that the northern and southern areas of Eastern Patagonia have different temperature variability in summer and autumn whereas the temperature variability tends to be more homogeneous within the region during winter and spring. Warm (cold) conditions in the northern areas are associated with reinforced (weakened) westerlies in summer, winter and spring whereas northerly (southerly) advections of warm (cold) air toward the region produce such conditions in autumn. Temperature in the southern portion of Eastern Patagonia is affected by anticyclonic (cyclonic) anomalies that enhance (reduce) the incoming solar radiation and induce reinforced (weakened) westerlies promoting warm (cold) conditions in the region. Furthermore, cyclonic (anticyclonic) anomalies at subpolar latitudes hinder (favor) outbreaks of cold air increasing (decreasing) the temperature over areas of Eastern Patagonia. The circulation anomalies associated with warm (cold) conditions in Eastern Patagonia also promote cold (warm) conditions over areas of northern Argentina, Paraguay and southern Brazil. Consequently, a dipole of temperature is detected in southern South America with centers of opposite sign over these regions.

  18. No increase in global temperature variability despite changing regional patterns.

    PubMed

    Huntingford, Chris; Jones, Philip D; Livina, Valerie N; Lenton, Timothy M; Cox, Peter M

    2013-08-15

    Evidence from Greenland ice cores shows that year-to-year temperature variability was probably higher in some past cold periods, but there is considerable interest in determining whether global warming is increasing climate variability at present. This interest is motivated by an understanding that increased variability and resulting extreme weather conditions may be more difficult for society to adapt to than altered mean conditions. So far, however, in spite of suggestions of increased variability, there is considerable uncertainty as to whether it is occurring. Here we show that although fluctuations in annual temperature have indeed shown substantial geographical variation over the past few decades, the time-evolving standard deviation of globally averaged temperature anomalies has been stable. A feature of the changes has been a tendency for many regions of low variability to experience increases, which might contribute to the perception of increased climate volatility. The normalization of temperature anomalies creates the impression of larger relative overall increases, but our use of absolute values, which we argue is a more appropriate approach, reveals little change. Regionally, greater year-to-year changes recently occurred in much of North America and Europe. Many climate models predict that total variability will ultimately decrease under high greenhouse gas concentrations, possibly associated with reductions in sea-ice cover. Our findings contradict the view that a warming world will automatically be one of more overall climatic variation. PMID:23883935

  19. 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.

  20. Solar-induced 27-day variations of mesospheric temperature and water vapor from the AIM SOFIE experiment: Drivers of polar mesospheric cloud variability

    NASA Astrophysics Data System (ADS)

    Thomas, Gary E.; Thurairajah, Brentha; Hervig, Mark E.; von Savigny, Christian; Snow, Martin

    2015-11-01

    Polar Mesospheric Clouds (PMCs) are known to be influenced by changes in water vapor and temperature in the cold summertime mesopause. Solar variability of these constituents has been held responsible for 11-year and 27-day variability of PMC activity, although the detailed mechanisms are not yet understood. It is also known that the solar influence on PMC variability is a minor contributor to the overall day-to-day variability, which is dominated by effects of gravity waves, planetary waves, and inter-hemispheric coupling. To address this issue, we have analyzed 15 seasons of data taken from the Solar Occultation for Ice Experiment (SOFIE) on the Aeronomy of Ice in the Mesosphere (AIM) satellite. The SOFIE data contain precise measurements of water vapor, temperature and ice water content (among other quantities). These high-latitude measurements are made during the PMC season at the terminator, and therefore directly relate to the simultaneous measurements of mesospheric ice. Using a composite data set of Lyman-α irradiance, we correlated the time variation of the atmospheric variables with the 27-day variability of solar ultraviolet irradiance. We used a combination of time-lagged linear regression and Superposed Epoch Analysis to extract the solar contribution as sensitivity values (response/forcing) vs. height. We compare these results to previously published results, and show that the temperature sensitivity is somewhat higher, whereas the water sensitivity is nearly the same as published values. The time lags are shorter than that expected from direct solar heating and photodissociation, suggesting that the responses are due to 27-day variations of vertical winds. An analytic solution for temperature changes forced by solar irradiance variations suggests that if the response is due purely to Lyman-α heating and Newtonian cooling, the response should vary throughout the summertime season and depend primarily upon the height-dependent column density of molecular oxygen.

  1. 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).

  2. Ocean versus atmosphere control on western European wintertime temperature variability

    NASA Astrophysics Data System (ADS)

    Yamamoto, Ayako; Palter, Jaime B.; Lozier, M. Susan; Bourqui, Michel S.; Leadbetter, Susan J.

    2015-12-01

    Using a novel Lagrangian approach, we assess the relative roles of the atmosphere and ocean in setting interannual variability in western European wintertime temperatures. We compute sensible and latent heat fluxes along atmospheric particle trajectories backtracked in time from four western European cities, using a Lagrangian atmospheric dispersion model driven with meteorological reanalysis data. The material time rate of change in potential temperature and the surface turbulent fluxes computed along the trajectory show a high degree of correlation, revealing a dominant control of ocean-atmosphere heat and moisture exchange in setting heat flux variability for atmospheric particles en route to western Europe. We conduct six idealised simulations in which one or more aspects of the climate system is held constant at climatological values and these idealised simulations are compared with a control simulation, in which all components of the climate system vary realistically. The results from these idealised simulations suggest that knowledge of atmospheric pathways is essential for reconstructing the interannual variability in heat flux and western European wintertime temperature, and that variability in these trajectories alone is sufficient to explain at least half of the internannual flux variability. Our idealised simulations also expose an important role for sea surface temperature in setting decadal scale variability of air-sea heat fluxes along the Lagrangian pathways. These results are consistent with previous studies showing that air-sea heat flux variability is driven by the atmosphere on interannual time scales over much of the North Atlantic, whereas the SST plays a leading role on longer time scales. Of particular interest is that the atmospheric control holds for the integrated fluxes along 10-day back trajectories from western Europe on an interannual time scale, despite that many of these trajectories pass over the Gulf Stream and its North Atlantic Current extension, regions where ocean dynamics influence air-sea heat exchange even on a very short time scale.

  3. Variability in Measured Space Temperatures in 60 Homes

    SciTech Connect

    Roberts, D.; Lay, K.

    2013-03-01

    This report discusses the observed variability in indoor space temperature in a set of 60 homes located in Florida, New York, Oregon, and Washington. Temperature data were collected at 15-minute intervals for an entire year, including living room, master bedroom, and outdoor air temperature (Arena, et. al). The data were examined to establish the average living room temperature for the set of homes for the heating and cooling seasons, the variability of living room temperature depending on climate, and the variability of indoor space temperature within the homes. The accuracy of software-based energy analysis depends on the accuracy of input values. Thermostat set point is one of the most influential inputs for building energy simulation. Several industry standards exist that recommend differing default thermostat settings for heating and cooling seasons. These standards were compared to the values calculated for this analysis. The data examined for this report show that there is a definite difference between the climates and that the data do not agree well with any particular standard.

  4. 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.

  5. 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.

  6. Variability in Temperature-Related Mortality Projections under Climate Change

    PubMed Central

    Benmarhnia, Tarik; Sottile, Marie-France; Plante, Céline; Brand, Allan; Casati, Barbara; Fournier, Michel

    2014-01-01

    Background: Most studies that have assessed impacts on mortality of future temperature increases have relied on a small number of simulations and have not addressed the variability and sources of uncertainty in their mortality projections. Objectives: We assessed the variability of temperature projections and dependent future mortality distributions, using a large panel of temperature simulations based on different climate models and emission scenarios. Methods: We used historical data from 1990 through 2007 for Montreal, Quebec, Canada, and Poisson regression models to estimate relative risks (RR) for daily nonaccidental mortality in association with three different daily temperature metrics (mean, minimum, and maximum temperature) during June through August. To estimate future numbers of deaths attributable to ambient temperatures and the uncertainty of the estimates, we used 32 different simulations of daily temperatures for June–August 2020–2037 derived from three global climate models (GCMs) and a Canadian regional climate model with three sets of RRs (one based on the observed historical data, and two on bootstrap samples that generated the 95% CI of the attributable number (AN) of deaths). We then used analysis of covariance to evaluate the influence of the simulation, the projected year, and the sets of RRs used to derive the attributable numbers of deaths. Results: We found that < 1% of the variability in the distributions of simulated temperature for June–August of 2020–2037 was explained by differences among the simulations. Estimated ANs for 2020–2037 ranged from 34 to 174 per summer (i.e., June–August). Most of the variability in mortality projections (38%) was related to the temperature–mortality RR used to estimate the ANs. Conclusions: The choice of the RR estimate for the association between temperature and mortality may be important to reduce uncertainty in mortality projections. Citation: Benmarhnia T, Sottile MF, Plante C, Brand A, Casati B, Fournier M, Smargiassi A. 2014. Variability in temperature-related mortality projections under climate change. Environ Health Perspect 122:1293–1298; http://dx.doi.org/10.1289/ehp.1306954 PMID:25036003

  7. Temperature variability in a shallow, tidally isolated coral reef lagoon

    NASA Astrophysics Data System (ADS)

    McCabe, R. M.; Estrade, P.; Middleton, J. H.; Melville, W. K.; Roughan, M.; Lenain, L.

    2010-12-01

    Temperature data collected in the shallow, tidally isolated reef flat/lagoon of Lady Elliot Island off Queensland, Australia, show marked variability under solar and tidal forcing. Sea level drops below the height of the protective lagoon rim for a few hours during low tide, effectively isolating the remaining water. Because the lagoon is shallow, its temperature change (from diurnal solar forcing and cooling) is amplified. We develop a simple analytical model to predict the time evolution of mean lagoon temperature, beginning with a well-mixed control volume. This approach highlights the asymmetric flood/ebb physics of tidally isolated lagoons. After discussing the response of this model, we compare it with results from two idealized numerical simulations that illustrate differing aspects of lagoon temperature variability under "potential flow" and "prevailing current" situations. The conceptual model captures the essence of lagoon temperature variability and underscores the importance of solar-lunar phasing. However, because of the well-mixed assumption, it cannot reproduce sudden temperature transitions associated with new incoming water masses. Observations show that a slowly progressing thermal wave inundates the lagoon on rising tides. This wave is similar to our "potential flow" simulation in that it is approximately radially symmetric. On the other hand, it appears to advectively replace resident lagoon water, similar to our "prevailing current" simulations. We attempt to account for this behavior with a simple "frontal" modification to our conceptual model. Results show that this frontal model is able to capture the sudden temperature transitions present in the data and offers improved predictive capabilities over the well-mixed model.

  8. 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.

  9. Inter-hemispheric temperature variability over the past millennium

    NASA Astrophysics Data System (ADS)

    Neukom, Raphael; Gergis, Joëlle; Karoly, David J.; Wanner, Heinz; Curran, Mark; Elbert, Julie; González-Rouco, Fidel; Linsley, Braddock K.; Moy, Andrew D.; Mundo, Ignacio; Raible, Christoph C.; Steig, Eric J.; van Ommen, Tas; Vance, Tessa; Villalba, Ricardo; Zinke, Jens; Frank, David

    2014-05-01

    The Earth's climate system is driven by a complex interplay of internal chaotic dynamics and natural and anthropogenic external forcing. Recent instrumental data have shown a remarkable degree of asynchronicity between Northern Hemisphere and Southern Hemisphere temperature fluctuations, thereby questioning the relative importance of internal versus external drivers of past as well as future climate variability. However, large-scale temperature reconstructions for the past millennium have focused on the Northern Hemisphere, limiting empirical assessments of inter-hemispheric variability on multi-decadal to centennial timescales. Here, we introduce a new millennial ensemble reconstruction of annually resolved temperature variations for the Southern Hemisphere based on an unprecedented network of terrestrial and oceanic palaeoclimate proxy records. In conjunction with an independent Northern Hemisphere temperature reconstruction ensemble, this record reveals an extended cold period (1594-1677) in both hemispheres but no globally coherent warm phase during the pre-industrial (1000-1850) era. The current (post-1974) warm phase is the only period of the past millennium where both hemispheres are likely to have experienced contemporaneous warm extremes. Our analysis of inter-hemispheric temperature variability in an ensemble of climate model simulations for the past millennium suggests that models tend to overemphasize Northern Hemisphere-Southern Hemisphere synchronicity by underestimating the role of internal ocean-atmosphere dynamics, particularly in the ocean-dominated Southern Hemisphere. Our results imply that climate system predictability on decadal to century timescales may be lower than expected based on assessments of external climate forcing and Northern Hemisphere temperature variations alone.

  10. Temperature variability and early clustering of record-breaking events

    NASA Astrophysics Data System (ADS)

    Anderson, Amalia; Kostinski, Alex

    2016-05-01

    As the number of climatological studies using record-breaking statistics is growing rapidly, understanding the sensitivity of the chosen time period becomes essential. To that end, here we examine the evolving variability of monthly mean temperatures and its dependence on beginning and final year. Specifically, we use an index, α, based on record-breaking statistics and employing reversibility such that < α>=0 indicates no trend in variability. Generally, < α> has decreased between 1900 and 2013, indicating decreasing variability relative to early decades for stations from the contiguous USA (United States Historical Climatology Network, version 2.5). We find, somewhat surprisingly, that the observed decrease is due to an early excess of records beginning in 1917 (record low value) and 1921 (record high value). While detailed results depend on whether the data is gridded, detrended, etc., the general finding appears remarkably robust and holds globally as well.

  11. Potential vorticity intrusion index and climate variability of surface temperature

    NASA Astrophysics Data System (ADS)

    Cai, M.

    2003-04-01

    This paper proposes a potential vorticity intrusion index (denoted as PVI) as an alternative diagnostic tool to study the observed climate variability/trend of the surface temperature. The PVI index is defined as the percentage area of upper lever PV intrusion in the extratropics at any given time. Abundance (shortage) of extreme cold surface air temperature episodes in high latitudes coincides with a high (low) PVI index. The interannual variability of the PVI index exhibits a strong QBO- like signal. The high (low) PVI index prevails when the equatorial zonal mean zonal wind at 50 hPa is easterly (westerly). The probability distribution map of PV intrusion activities shows a shift of the preferred regions of frontogenesis from the oceans to the continents when the PVI index is high. This explains directly why more extreme cold events are observed over the northern Eurasian and Northern America continents when the PVI index is high or the QBO is in the easterly phase.

  12. Potential vorticity intrusion index and climate variability of surface temperature

    NASA Astrophysics Data System (ADS)

    Cai, Ming

    2003-02-01

    This paper proposes a potential vorticity intrusion index (denoted as PVI) as an alternative diagnostic tool to study the observed climate variability/trend of the surface temperature. The PVI index measures the percentage area of upper lever PV intrusion in the extratropics at any given time. More (fewer) outbreaks of extreme cold surface air temperature in high latitudes take place when the PVI index is high (low). The interannual variability of the PVI index exhibits a strong QBO- like signal. The high (low) PVI index prevails when the equatorial zonal mean zonal wind at 50 hPa is easterly (westerly). The probability distribution map of PV intrusion activities shows a shift of the preferred regions of frontogenesis from the oceans to the continents when the PVI index is high. This explains directly why more extreme cold events are observed over the northern Eurasian and Northern America continents when the PVI index is high, or the QBO is in the easterly phase.

  13. Subseasonal variability of North American wintertime surface air temperature

    NASA Astrophysics Data System (ADS)

    Lin, Hai

    2015-09-01

    Using observational pentad data of the recent 34 Northern Hemisphere extended winters, subseasonal variability of surface air temperature (SAT) over North America is analyzed. The four leading modes of subseasonal SAT variability, that are identified with an empirical orthogonal function (EOF) analysis, account for about 60% of the total variance. The first (EOF1) and second (EOF2) modes are independent of other modes, and thus are likely controlled by distinct processes. The third (EOF3) and fourth (EOF4) modes, however, tend to have a phase shift to each other in space and time, indicating that part of their variability is related to a common process and represent a propagating pattern over North America. Lagged regression analysis is conducted to identify the precursors of large-scale atmospheric circulation for each mode a few pentads in advance, and to understand the processes that influence the subseasonal SAT variability and the predictability signal sources. EOF1 is found to be closely related to the Pacific-North American (PNA) circulation pattern and at least part of its variability is preceded by the East Asian cold surge. The cold surge leads to low-level convergence and enhanced convection in the tropical central Pacific which in turn induces the PNA. EOF2 tends to oscillate at a period of about 70 days, and is influenced by the low-frequency component of the Madden-Julian Oscillation (MJO). On the other hand, EOF3 and EOF4 are connected to the high-frequency part of the MJO which has a period range of 30-50 days. These findings would help understanding the mechanisms of subseasonal surface air temperature variability in North America and improving weather predictions on a subseasonal time scale.

  14. Water temperature variability within an Arctic stream; analysis and implications

    NASA Astrophysics Data System (ADS)

    Mellor, C. J.; Hannah, D. M.; Milner, A. M.

    2009-04-01

    Arctic climate warming occurred at twice the global average over the last century and air temperature is predicted to increase by 7.5°C by 2099. Arctic river systems are hypothesized to be particularly vulnerable to warming due to their dependence on cryospheric water sources and thermal sensitivity of biotic communities. However, research is very limited on hydroecological response of Arctic rivers to a changing climate. This paper addresses this research gap and aims to investigate links between thermal dynamics and benthic communities for a river basin in Swedish Lappland. The Kårsavagge is located ~200 km north of the Arctic Circle and contains a small temperate glacier and two lakes. The Kårsa River drains into the Abisko River (~ 25 km from the valley head). The region experiences marked seasonality with average monthly air temperature ranging from +10 to -10°C. In June 2008, three gauging stations (1 - close to glacier snout, 2 - above first major extra glacial tributary and 3 - between the lakes and confluence with the Abisko river) were installed to record water temperature, riverbed temperature (at 0.05m, 0.20m and 0.40m depth), electrical conductivity, river stage, precipitation and turbidity. On top of these, twenty loggers recorded water temperature between gauging stations and across a braided reach located ~ 1.5km downstream of the glacier snout. Diurnal water temperature cycles were found at all sites; but average temperature increased downstream from 1.7°C near the glacier snout to 10.6°C before the Abisko River confluence. Sites immediately downstream of the lakes displayed moderated thermal variability. Bed temperatures in the upper catchment (lower) were higher (lower) and less variable that temperatures in the overlying water column. The degree of parity between water column and stream bed temperatures varied among sites with site 3 showing the greatest difference and site 2 showing the least. This implies a variable degree of connectivity between the water column and bed sediments and/or variation in the extent and source water of upwelling. Average temperature across the braided reach ranged from 2.8°C in the main glacier fed (kryal) channel to 8.8°C in a snowmelt (nival) channel sourced from north-facing slopes, reflecting the differential impact of solar heating on water from these two distinct sources. Chironomidae (non-biting midges) dominated the benthic communities in the upper catchment where maximum water temperature did not exceed 4.4°C. As distance from the glacier and water temperature increases other taxa appear (e.g. Plecoptera, Simulidae), with species richness and diversity peaking between the two lakes. Longitudinal changes in thermal regime are associated with shifts in the benthic invertebrate community. Work is ongoing to evaluate whether the observed lateral variation, which is close to that observed down the 25km longitudinal profile has similar implications. This lateral variability may be important in providing thermal refugia and therefore increasing biota diversity in the upper catchment. This work has highlighted the potential extent of longitudinal, vertical and lateral temperature variation within Arctic river systems. In combination with invertebrate distribution this could be used to identify communities at high risk from changes in thermal regime and further, identify species which can act as indicators of the changing Arctic climate.

  15. Temperature fluctuations as a source of brown dwarf variability

    SciTech Connect

    Robinson, Tyler D.; Marley, Mark S.

    2014-04-20

    A number of brown dwarfs are now known to be variable with observed amplitudes as large as 10%-30% at some wavelengths. While spatial inhomogeneities in cloud coverage and thickness are likely responsible for much of the observed variability, it is possible that some of the variations arise from atmospheric temperature fluctuations instead of, or in addition to, clouds. To better understand the role that thermal variability might play we present a case study of brown dwarf variability using a newly developed one-dimensional, time-stepping model of atmospheric thermal structure. We focus on the effects of thermal perturbations, intentionally simplifying the problem through omission of clouds and atmospheric circulation. Model results demonstrate that thermal perturbations occurring deep in the atmosphere (at pressures greater than 10 bar) of a model T-dwarf can be communicated to the upper atmosphere through radiative heating via the windows in near-infrared water opacity. The response time depends on where in the atmosphere a thermal perturbation is introduced. We show that, for certain periodic perturbations, the emission spectrum can have complex time- and wavelength-dependent behaviors, including phase shifts in times of maximum flux observed at different wavelengths. Since different wavelengths probe different levels in the atmosphere, these variations track a wavelength-dependent set of radiative exchanges happening between different atmospheric levels as a perturbation evolves in time. We conclude that thermal—as well as cloud—fluctuations must be considered as possible contributors to the observed brown dwarf variability.

  16. Wintertime Temperature Variability In South America Between 1948-2007

    NASA Astrophysics Data System (ADS)

    Chaves, R. R.; Collins, J.; Pugh, K.; Marques, V. D.

    2008-05-01

    The wintertime temperature variability is analyzed in South America between 1948-2007. We use 2 meter surface air temperature data from the NCEP/NCAR reanalysis in June-July-August (JJA). The mean temperature is above 24°C in the Amazon region and in the northern part of Northeast Brazil between 1948-2007. However, in the period 1976-2007, the area with temperatures above 24°C increases in size. Thus, we observe warmer temperatures in the tropical region in 1976-2007 compared to 1948-1975. The differences in wintertime mean temperature between these two periods are more evident in the tropical region. In the North Atlantic Ocean, the sea surface temperature is also greater during 1976-2007 with values above 27°C along the northern coastline of South America. The western part of the South Atlantic Ocean is also warmer during 1976-2007 with southward displacement of the 24°C isotherm. There is a warming of 0.9 °C in central Brazil in 1976-2007 compared to the earlier period. In Northeast Brazil and in the north of South America, we observe warming above 0.6°C and 0.3°C respectively in the second period. When the second period is sub-divided (1976-91 and 1992-2007), the temperature pattern in South America does not show an accentuated difference between the two periods. However, the difference between the mean temperature between these periods shows warming in the central Amazon region, Argentina, the Uruguay Coast and the equatorial tropical North Atlantic Ocean near South America and cooling in the central Andes Cordillera and Chile. Considering the difference of mean temperatures between 1976-91 to 1948-75 and 1992-2007 to 1948-75, during 1992-2007, the area with warming in South America increased in the central part of South America, Northeast Brazil and the North Atlantic Ocean near South America. In the central Amazon region, we observe a cooling of 0.6°C during 1976-1991, when compared to 1948-75. The interannual temperature variability of JJA, determined by the standard deviation, is not strong over the majority of South America, except over subtropical latitudes, where this is greater in the period between 1992-2007. The results here suggest that the warming may not be due to the El Niño phenomenon, but some other factor such as an anthropogenic influence.

  17. 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.

  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. Tropical Indian Ocean subsurface temperature variability and the forcing mechanisms

    NASA Astrophysics Data System (ADS)

    Sayantani, Ojha; Gnanaseelan, C.

    2015-05-01

    The first two leading modes of interannual variability of sea surface temperature in the Tropical Indian Ocean (TIO) are governed by El Niño Southern Oscillation and Indian Ocean Dipole (IOD) respectively. TIO subsurface however does not co-vary with the surface. The patterns of the first mode of TIO subsurface temperature variability and their vertical structure are found to closely resemble the patterns of IOD and El Niño co-occurrence years. These co-occurrence years are characterized by a north-south subsurface dipole rather than a conventional IOD forced east-west dipole. This subsurface dipole is forced by wind stress curl anomalies, driven mainly by meridional shear in the zonal wind anomalies. A new subsurface dipole index (SDI) has been defined in this study to quantify the intensity of the north-south dipole mode. The SDI peaks during December to February (DJF), a season after the dipole mode index peaks. It is found that this subsurface north-south dipole is a manifestation of the internal mode of variability of the Indian Ocean forced by IOD but modulated by Pacific forcing. The seasonal evolution of thermocline, subsurface temperature and the corresponding leading modes of variability further support this hypothesis. Positive wind stress curl anomalies in the south and negative wind stress curl anomalies in the north of 5°S force (or intensify) downwelling and upwelling waves respectively during DJF. These waves induce strong subsurface warming in the south and cooling in the north (especially during DJF) and assist the formation and/or maintenance of the north-south subsurface dipole. A thick barrier layer forms in the southern TIO, supporting the long persistence of anomalous subsurface warming. To the best of our knowledge the existence of such north-south subsurface dipole in TIO is being reported for the first time.

  20. Low vibration high numerical aperture automated variable temperature Raman microscope

    NASA Astrophysics Data System (ADS)

    Tian, Yao; Reijnders, Anjan A.; Osterhoudt, Gavin B.; Valmianski, Ilya; Ramirez, J. G.; Urban, Christian; Zhong, Ruidan; Schneeloch, John; Gu, Genda; Henslee, Isaac; Burch, Kenneth S.

    2016-04-01

    Raman micro-spectroscopy is well suited for studying a variety of properties and has been applied to a wide range of areas. Combined with tuneable temperature, Raman spectra can offer even more insights into the properties of materials. However, previous designs of variable temperature Raman microscopes have made it extremely challenging to measure samples with low signal levels due to thermal and positional instabilities as well as low collection efficiencies. Thus contemporary Raman microscope has found limited applicability to probing the subtle physics involved in phase transitions and hysteresis. This paper describes a new design of a closed-cycle, Raman microscope with full polarization rotation. High collection efficiency, thermal stability, and mechanical stability are ensured by both deliberate optical, cryogenic, and mechanical design. Measurements on two samples, Bi2Se3 and V2O3, which are challenging due to low thermal conductivities, low signal levels, and/or hysteretic effects, are measured with previously undemonstrated temperature resolution.

  1. Temperature and Precipitation Trends and Variability in Alaska Since 1950

    NASA Astrophysics Data System (ADS)

    Shulski, M. D.; Stuefer, M.; Hartmann, B.; Wendler, G.

    2002-12-01

    The northern hemisphere has experienced a general warming trend in recent decades that is most pronounced at high latitudes. For Alaska, the mean annual temperature has increased approximately 1.4°C for the most recent climate normal (1971-2000). However, it is important to note that the increase is non-linear and exhibits seasonal and spatial variability. In this investigation, climate records for first-order observing stations in Alaska were examined for the period 1950 to 2001. Spatial coverage is such that the three climate regimes in the state (arctic, continental, and maritime) are represented. Seasonal temperature trends show that the greatest warming has occurred in winter. Furthermore, the trend is greater for minimum temperatures than maximum. Although most locations show an increase in snowfall, there is also a coincident decrease in total annual precipitation, the former largely due to an increase in autumn snowfall total.

  2. Low vibration high numerical aperture automated variable temperature Raman microscope.

    PubMed

    Tian, Yao; Reijnders, Anjan A; Osterhoudt, Gavin B; Valmianski, Ilya; Ramirez, J G; Urban, Christian; Zhong, Ruidan; Schneeloch, John; Gu, Genda; Henslee, Isaac; Burch, Kenneth S

    2016-04-01

    Raman micro-spectroscopy is well suited for studying a variety of properties and has been applied to a wide range of areas. Combined with tuneable temperature, Raman spectra can offer even more insights into the properties of materials. However, previous designs of variable temperature Raman microscopes have made it extremely challenging to measure samples with low signal levels due to thermal and positional instabilities as well as low collection efficiencies. Thus contemporary Raman microscope has found limited applicability to probing the subtle physics involved in phase transitions and hysteresis. This paper describes a new design of a closed-cycle, Raman microscope with full polarization rotation. High collection efficiency, thermal stability, and mechanical stability are ensured by both deliberate optical, cryogenic, and mechanical design. Measurements on two samples, Bi2Se3 and V2O3, which are challenging due to low thermal conductivities, low signal levels, and/or hysteretic effects, are measured with previously undemonstrated temperature resolution. PMID:27131652

  3. 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).

  4. Bottom temperature and salinity distribution and its variability around Iceland

    NASA Astrophysics Data System (ADS)

    Jochumsen, Kerstin; Schnurr, Sarah M.; Quadfasel, Detlef

    2016-05-01

    The barrier formed by the Greenland-Scotland-Ridge (GSR) shapes the oceanic conditions in the region around Iceland. Deep water cannot be exchanged across the ridge, and only limited water mass exchange in intermediate layers is possible through deep channels, where the flow is directed southwestward (the Nordic Overflows). As a result, the near-bottom water masses in the deep basins of the northern North Atlantic and the Nordic Seas hold major temperature differences. Here, we use near-bottom measurements of about 88,000 CTD (conductivity-temperature-depth) and bottle profiles, collected in the period 1900-2008, to investigate the distribution of near-bottom properties. Data are gridded into regular boxes of about 11 km size and interpolated following isobaths. We derive average spatial temperature and salinity distributions in the region around Iceland, showing the influence of the GSR on the near-bottom hydrography. The spatial distribution of standard deviation is used to identify local variability, which is enhanced near water mass fronts. Finally, property changes within the period 1975-2008 are presented using time series analysis techniques for a collection of grid boxes with sufficient data resolution. Seasonal variability, as well as long term trends are discussed for different bottom depth classes, representing varying water masses. The seasonal cycle is most pronounced in temperature and decreases with depth (mean amplitudes of 2.2 °C in the near surface layers vs. 0.2 °C at depths > 500 m), while linear trends are evident in both temperature and salinity (maxima in shallow waters of +0.33 °C/decade for temperature and +0.03/decade for salinity).

  5. Implementation of Temperature Sequential Controller on Variable Speed Drive

    NASA Astrophysics Data System (ADS)

    Cheong, Z. X.; Barsoum, N. N.

    2008-10-01

    There are many pump and motor installations with quite extensive speed variation, such as Sago conveyor, heating, ventilation and air conditioning (HVAC) and water pumping system. A common solution for these applications is to run several fixed speed motors in parallel, with flow control accomplish by turning the motors on and off. This type of control method causes high in-rush current, and adds a risk of damage caused by pressure transients. This paper explains the design and implementation of a temperature speed control system for use in industrial and commercial sectors. Advanced temperature speed control can be achieved by using ABB ACS800 variable speed drive-direct torque sequential control macro, programmable logic controller and temperature transmitter. The principle of direct torque sequential control macro (DTC-SC) is based on the control of torque and flux utilizing the stator flux field orientation over seven preset constant speed. As a result of continuous comparison of ambient temperature to the references temperatures; electromagnetic torque response is particularly fast to the motor state and it is able maintain constant speeds. Experimental tests have been carried out by using ABB ACS800-U1-0003-2, to validate the effectiveness and dynamic respond of ABB ACS800 against temperature variation, loads, and mechanical shocks.

  6. Infrared-temperature variability in a large agricultural field

    NASA Technical Reports Server (NTRS)

    Millard, J. P.; Goettelman, R. C.; Leroy, M. J.

    1981-01-01

    Dunnigan Agro-Meteorological Experiment airborne thermal scanner images of a large varying-terrain barley field are acquired and analyzed. Temperature variability that may occur within instantaneous fields of view (IFOV) is defined (coefficient of variation: standard deviation/mean temperature in degrees C), and the percentage of the area within various IFOV's within + or - 1, 2, 3, and 5 degrees of the mean is determined. With the exception of very rugged terrain, over 80% of the area within 4, 16, 65 and 258 ha cells was at temperatures within + or - 3 C of the mean cell temperature. Remote measurements of field temperature appeared to be slightly influenced by pixel size in the range 4 ha to 259 ha, and the area percentage within any pixel which contributes within + or - 1, 2, 3, and 5 degrees C of the mean, is nominally the same. In conclusion, no great advantage is found in utilizing a small IFOV instead of a large one for remote sensing of crop temperature.

  7. Trend and interannual variability of temperature in Malaysia: 1961 2002

    NASA Astrophysics Data System (ADS)

    Tangang, F. T.; Juneng, L.; Ahmad, S.

    2007-07-01

    This paper investigates the warming trend and interannual variability of surface air temperatures in the Malaysian region during the period 1961 2002. The trend analyses show that most regions in Malaysia experience warming over the period at comparable rates to those in regions surrounding the Bay of Bengal. The regions of Peninsular Malaysia and northern Borneo experience warming rates of between 2.7 4.0 °C/100 years. However, the warming rates are lower in the south-western region of Borneo. The interannual variability of Malaysian temperature is largely dominated by the El Niño-Southern Oscillation (ENSO). Regardless of the warming trends, all regions in Malaysia experience uniform warming during an El Niño event, particularly during the October November December (OND) and the January February March (JFM) periods. This uniform warming is associated with the latent heat released from the central eastern Pacific region and forced adiabatic subsidence in the Maritime Continent during an El Niño event. During its early development period i.e. during the July August September (JAS) season, the El Niño’s impact on the Malaysian temperatures is relatively weak compare to its influence during the OND and JFM seasons. However, the warming continues to the April May June (AMJ) season although during this period the anomalous conditions in the eastern central Pacific have begun or have returned to normal. The Indian Ocean Dipole (IOD) mode exerts an influence on Malaysian temperatures. When it co-occurs with ENSO, it tends to weaken the ENSO influence particularly during an OND period. However, it appears to have an appreciable influence only during an AMJ period when it occurs in the absence of an ENSO event. Despite the strong influence of the ENSO, the warming rates during the 42-year period appears to be least affected by interannual variability.

  8. 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.

  9. Beyond extreme temperatures: soil water supply and yield variability

    NASA Astrophysics Data System (ADS)

    Urban, D.; Lobell, D. B.

    2014-12-01

    Extreme weather events have profound consequences for both the mean and interannual variability of agricultural production, but while the role of extreme heat has been convincingly demonstrated, soil water supply has received less attention. In particular, there is debate over the extent to which damages attributed to extreme heat are confounded with drought conditions. In a pair of studies, we examine the effect of extreme moisture conditions, both wet and dry, on maize and soybean yields in the U.S. We find significant effects of waterlogging during the planting season, when crops are most vulnerable to excess moisture, as well as evidence for a strong interaction between high temperatures and low moisture during during the critical stages of the summer growing season. Using both precipitation and model-derived soil moisture data, our results suggest that considering temperature and moisture independently will underestimate yield damages during hot, dry conditions. Many warming scenarios project increases in both extreme summer temperatures and soil dryness, and considering these effects jointly can be important in estimating future yield variability.

  10. Spatial and temporal variability of daily temperature in the Yangtze River Delta, China

    NASA Astrophysics Data System (ADS)

    Sang, Yan-Fang

    2012-08-01

    In this paper, the variability of daily temperature in the Yangtze River Delta (YRD) for the period 1958-2007 was investigated by selecting three typical temperature variables (daily minimum, mean and maximum temperatures) and the diurnal temperature range (DTR). Three variability patterns of daily mean temperature and two variability patterns of daily minimum and maximum temperatures were first classed, and then statistical properties of three temperature variables in 1958-1985 and 1986-2007 were analyzed. After that, temporal trends of three temperature variables and DTR were detected. Finally, the impacts of urbanization on the variability of daily temperature were investigated. Results indicate that: (1) daily mean temperature shows more complex variability than daily minimum and maximum temperatures; (2) in 1986-2007 three temperature variables have bigger mean values but smaller Cv (coefficient of variance) values, and are more close to normal probability distribution; (3) three temperature variables show positive trends in 1986-2007, and the increase of daily mean temperature is more due to the increase of daily minimum temperature in the northern YRD but due to daily maximum temperature in the mid and southern YRD; (4) in the mid and southern YRD, daily maximum temperature has bigger increasing magnitude than daily minimum temperature in 1986-2007, causing positive trend of DTR; and (5) rapid urbanization causes normal distribution of three temperature variables, and notably increasing magnitude of daily temperature and DTR in 1986-2007 at the lower reaches of the Yangtze River and the Hangzhou Bay.

  11. Prediction of Core Body Temperature from Multiple Variables.

    PubMed

    Richmond, Victoria L; Davey, Sarah; Griggs, Katy; Havenith, George

    2015-11-01

    This paper aims to improve the prediction of rectal temperature (T re) from insulated skin temperature (T is) and micro-climate temperature (T mc) previously reported (Richmond et al., Insulated skin temperature as a measure of core body temperature for individuals wearing CBRN protective clothing. Physiol Meas 2013; 34:1531-43.) using additional physiological and/or environmental variables, under several clothing and climatic conditions. Twelve male (25.8±5.1 years; 73.6±11.5kg; 178±6cm) and nine female (24.2±5.1 years; 62.4±11.5kg; 169±3cm) volunteers completed six trials, each consisting of two 40-min periods of treadmill walking separated by a 20-min rest, wearing permeable or impermeable clothing, under neutral (25°C, 50%), moderate (35°C, 35%), and hot (40°C, 25%) conditions, with and without solar radiation (600W m(-2)). Participants were measured for heart rate (HR) (Polar, Finland), skin temperature (T s) at 11 sites, T is (Grant, Cambridge, UK), and breathing rate (f) (Hidalgo, Cambridge, UK). T mc and relative humidity were measured within the clothing. T re was monitored as the 'gold standard' measure of T c for industrial or military applications using a 10cm flexible probe (Grant, Cambridge, UK). A stepwise multiple regression analysis was run to determine which of 30 variables (T is, T s at 11 sites, HR, f, T mc, temperature, and humidity inside the clothing front and back, body mass, age, body fat, sex, clothing, Thermal comfort, sensation and perception, and sweat rate) were the strongest on which to base the model. Using a bootstrap methodology to develop the equation, the best model in terms of practicality and validity included T is, T mc, HR, and 'work' (0 = rest; 1 = exercise), predicting T re with a standard error of the estimate of 0.27°C and adjusted r (2) of 0.86. The sensitivity and specificity for predicting individuals who reached 39°C was 97 and 85%, respectively. Insulated skin temperature was the most important individual parameter for the prediction of T re. This paper provides novel information about the viability of predicting T c under a wide range of conditions, using predictors which can practically be measured in a field environment. PMID:26268995

  12. 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.

  13. Variability of Battery Wear in Light Duty Plug-In Electric Vehicles Subject to Ambient Temperature, Battery Size, and Consumer Usage: Preprint

    SciTech Connect

    Wood, E.; Neubauer, J.; Brooker, A. D.; Gonder, J.; Smith, K. A.

    2012-08-01

    Battery wear in plug-in electric vehicles (PEVs) is a complex function of ambient temperature, battery size, and disparate usage. Simulations capturing varying ambient temperature profiles, battery sizes, and driving patterns are of great value to battery and vehicle manufacturers. A predictive battery wear model developed by the National Renewable Energy Laboratory captures the effects of multiple cycling and storage conditions in a representative lithium chemistry. The sensitivity of battery wear rates to ambient conditions, maximum allowable depth-of-discharge, and vehicle miles travelled is explored for two midsize vehicles: a battery electric vehicle (BEV) with a nominal range of 75 mi (121 km) and a plug-in hybrid electric vehicle (PHEV) with a nominal charge-depleting range of 40 mi (64 km). Driving distance distributions represent the variability of vehicle use, both vehicle-to-vehicle and day-to-day. Battery wear over an 8-year period was dominated by ambient conditions for the BEV with capacity fade ranging from 19% to 32% while the PHEV was most sensitive to maximum allowable depth-of-discharge with capacity fade ranging from 16% to 24%. The BEV and PHEV were comparable in terms of petroleum displacement potential after 8 years of service, due to the BEV?s limited utility for accomplishing long trips.

  14. Interannual Temperature Variability and Associated Synoptic Climatology at Cape Town

    NASA Astrophysics Data System (ADS)

    Levey, Kevin M.

    1996-03-01

    Interannual temperature variability at Cape Town over the period 1877-1991 is investigated. A quasi-periodicity of 8-16 years is evident. The regional structure of warm and cold years is described using lower and upper level wind, outgoing longwave radiation (OLR), and sea-surface temperature (SST). Anomalously warm (cold) periods at Cape Town are associated with the persistence of weaker (stronger) westerlies, which are located further polewards (equatorwards) than usual. The OLR fields indicate a poleward shift of zonal westerly cloud bands in warm years coincident with a tongue of positive SST anomalies to the south of Cape Town. The positioning of standing waves in the mid-latitude westerlies is a determinant of thermal advection and appear to adjust to underlying SST fields.

  15. 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.

  16. Assessing surface air temperature variability using quantile regression

    NASA Astrophysics Data System (ADS)

    Timofeev, A. A.; Sterin, A. M.

    2014-12-01

    Many researches in climate change currently involve linear trends, based on measured variables. And many of them only consider trends in mean values, whereas it is clear, that not only means, but also whole shape of distribution changes over time and requires careful assessment. For example extreme values including outliers may get bigger, while median has zero slope.Quantile regression provides a convenient tool, that enables detailed analysis of changes in full range of distribution by producing a vector of quantile trends for any given set of quantiles.We have applied quantile regression to surface air temperature observations made at over 600 weather stations across Russian Federation during last four decades. The results demonstrate well pronounced regions with similar values of significant trends in different parts of temperature value distribution (left tail, middle part, right tail). The uncertainties of quantile trend estimations for several spatial patterns of trends over Russia are estimated and analyzed for each of four seasons.For temperature trend estimation over vast territories, quantile regression is an effort consuming approach, but is more informative than traditional instrument, to assess decadal evolution of temperature values, including evolution of extremes.Partial support of ERA NET RUS ACPCA joint project between EU and RBRF 12-05-91656-ЭРА-А is highly appreciated.

  17. Predictability of Mediterranean climate variables from oceanic variability. Part I: Sea surface temperature regimes

    NASA Astrophysics Data System (ADS)

    Hertig, E.; Jacobeit, J.

    2011-03-01

    The determination of specific sea surface temperature (SST) patterns from large-scale gridded SST-fields has widely been done. Often principal component analysis (PCA) is used to condense the SST-data to major patterns of variability. In the present study SST-fields for the period 1950-2003 from the area 20°S to 60°N are analysed with respect to SST-regimes being defined as large-scale oceanic patterns with a regular and at least seasonal occurrence. This has been done in context of investigations on seasonal predictability of Mediterranean regional climate with large-scale SST-regimes as intended predictors in statistical model relationships. The SST-regimes are derived by means of a particular technique including multiple applications of s-mode PCA. Altogether 17 stationary regimes can be identified, eight for the Pacific Ocean, five for the Atlantic Ocean, two for the Indian Ocean, and two regimes which show a distinct co-variability within different ocean basins. Some regimes exist, with varying strength and spatial extent, throughout the whole year, whereas other regimes are only characteristic for a particular season. Several regimes show dominant variability modes, like the regimes associated with El Niño, with the Pacific Decadal Oscillation or with the North Atlantic Tripole, whereas other regimes describe little-known patterns of large-scale SST variability. The determined SST-regimes are subsequently used as predictors for monthly precipitation and temperature in the Mediterranean area. This subject is addressed in Part II of this paper.

  18. Variability in daily, zonal mean lower-stratospheric temperatures

    SciTech Connect

    Christy, J.R. ); Drouilhet, S.J. Jr. )

    1994-01-01

    Satellite data from the microwave sounding unit (MSU) channel 4, when carefully merged, provide daily zonal anomalies of lower-stratosphere temperature with a level of precision between 0.01[degrees] and 0.08[degrees]C per 2.5[degrees] latitude band. Global averages of these daily zonal anomalies reveal the prominent warming events due to volcanic aerosol in 1982 (El Chichon) and 1991 (Mt. Pinatubo), which are on the order of 1[degrees]C. The quasibiennel oscillation (QBO) may be extracted from these zonal data by applying a spatial filter between 15[degrees]N and 15[degrees]S latitude, which resembles the meridional curvature. Previously published relationships between the QBO and the north polar stratospheric temperatures during northern winter are examined but were not found to be reproduced in the MSU4 data. Sudden stratospheric warmings in the north polar region are represented in the MSU4 data for latitudes poleward of 70[degrees]N. In the Southern Hemisphere, there appears to be a moderate relationship between total ozone concentration and MSU4 temperatures, though it has been less apparent in 1991 and 1992. In terms of empirical modes of variability revealed significant power in the 15-20 day period band.

  19. Variability in daily, zonal mean lower-stratospheric temperatures

    NASA Technical Reports Server (NTRS)

    Christy, John R.; Drouilhet, S. James, Jr.

    1994-01-01

    Satellite data from the microwave sounding unit (MSU) channel 4, when carefully merged, provide daily zonal anomalies of lower-stratosphere temperature with a level of precision between 0.01 and 0.08 C per 2.5 deg latitude band. Global averages of these daily zonal anomalies reveal the prominent warming events due to volcanic aerosol in 1982 (El Chichon) and 1991 (Mt. Pinatubo), which are on the order of 1 C. The quasibiennial oscillation (QBO) may be extracted from these zonal data by applying a spatial filter between 15 deg N and 15 deg S latitude, which resembles the meridional curvature. Previously published relationships between the QBO and the north polar stratospheric temperatures during northern winter are examined but were not found to be reproduced in the MSU4 data. Sudden stratospheric warmings in the north polar region are represented in the MSU4 data for latitudes poleward of 70 deg N. In the Southern Hemisphere, there appears to be a moderate relationship between total ozone concentration and MSU4 temperatures, though it has been less apparent in 1991 and 1992. In terms of empirical modes of variability, the authors find a strong tendency in EOF 1 (39.2% of the variance) for anomalies in the Northern Hemisphere polar regions to be counterbalanced by anomalies equatorward of 40 deg N and 40 deg S latitudes. In addition, most of the modes revealed significant power in the 15-20 day period band.

  20. 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.

  1. Simple insertible high performance variable temperature regulator for measurement of physical properties at low temperature

    NASA Astrophysics Data System (ADS)

    Nagendran, R.; Satya, A. T.; Chinnasamy, N.; Baskaran, R.; Janawadkar, M. P.

    2016-04-01

    An impedance capillary based Variable Temperature Regulator (VTR) for regulation of temperature in the range of 4.2 K-300 K, which can be detached and inserted into any experimental setup with a 50 mm diameter top access, has been designed, fabricated, and tested. The VTR may be used as a highly compact probe, which can be readily inserted in any liquid helium dewar or cryostat to realize uniform rates of cooling/heating and to achieve excellent temperature stability of ±1 mK at any temperature between 4.2 K and 300 K. VTR has been subjected to extensive experimental testing to arrive at optimum values of control parameters that are expected to influence its performance. The VTR may be integrated into any experimental setup for measurement of physical properties at low temperatures.

  2. Simple insertible high performance variable temperature regulator for measurement of physical properties at low temperature.

    PubMed

    Nagendran, R; Satya, A T; Chinnasamy, N; Baskaran, R; Janawadkar, M P

    2016-04-01

    An impedance capillary based Variable Temperature Regulator (VTR) for regulation of temperature in the range of 4.2 K-300 K, which can be detached and inserted into any experimental setup with a 50 mm diameter top access, has been designed, fabricated, and tested. The VTR may be used as a highly compact probe, which can be readily inserted in any liquid helium dewar or cryostat to realize uniform rates of cooling/heating and to achieve excellent temperature stability of ±1 mK at any temperature between 4.2 K and 300 K. VTR has been subjected to extensive experimental testing to arrive at optimum values of control parameters that are expected to influence its performance. The VTR may be integrated into any experimental setup for measurement of physical properties at low temperatures. PMID:27131702

  3. Causes of Greenland temperature variability over the past 4000 yr: implications for northern hemispheric temperature changes

    NASA Astrophysics Data System (ADS)

    Kobashi, T.; Goto-Azuma, K.; Box, J. E.; Gao, C.-C.; Nakaegawa, T.

    2013-10-01

    Precise understanding of Greenland temperature variability is important in two ways. First, Greenland ice sheet melting associated with rising temperature is a major global sea level forcing, potentially affecting large populations in coming centuries. Second, Greenland temperatures are highly affected by North Atlantic Oscillation/Arctic Oscillation (NAO/AO) and Atlantic multidecadal oscillation (AMO). In our earlier study, we found that Greenland temperature deviated negatively (positively) from northern hemispheric (NH) temperature trend during stronger (weaker) solar activity owing to changes in atmospheric/oceanic changes (e.g. NAO/AO) over the past 800 yr (Kobashi et al., 2013). Therefore, a precise Greenland temperature record can provide important constraints on the past atmospheric/oceanic circulation in the region and beyond. Here, we investigated Greenland temperature variability over the past 4000 yr reconstructed from argon and nitrogen isotopes from trapped air in a GISP2 ice core, using a one-dimensional energy balance model with orbital, solar, volcanic, greenhouse gas, and aerosol forcings. The modelled northern Northern Hemisphere (NH) temperature exhibits a cooling trend over the past 4000 yr as observed for the reconstructed Greenland temperature through decreasing annual average insolation. With consideration of the negative influence of solar variability, the modelled and observed Greenland temperatures agree with correlation coefficients of r = 0.34-0.36 (p = 0.1-0.04) in 21 yr running means (RMs) and r = 0.38-0.45 (p = 0.1-0.05) on a centennial timescale (101 yr RMs). Thus, the model can explain 14 to 20% of variance of the observed Greenland temperature in multidecadal to centennial timescales with a 90-96% confidence interval, suggesting that a weak but persistent negative solar influence on Greenland temperature continued over the past 4000 yr. Then, we estimated the distribution of multidecadal NH and northern high-latitude temperatures over the past 4000 yr constrained by the climate model and Greenland temperatures. Estimated northern NH temperature and NH average temperature from the model and the Greenland temperature agree with published multi-proxy temperature records with r = 0.35-0.60 in a 92-99% confidence interval over the past 2000 yr. We found that greenhouse gases played two important roles over the past 4000 yr for the rapid warming during the 20th century and slightly cooler temperature during the early period of the past 4000 yr. Lastly, our analysis indicated that the current average temperature (1990-2010) or higher temperatures occurred at a frequency of 1.3 times per 1000 yr for northern high latitudes and 0.36 times per 4000 yr for NH temperatures, respectively, indicating that the current multidecadal NH temperature (1990-2010) is more likely unprecedented than not (p = 0.36) for the past 4000 yr.

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

    NASA Astrophysics Data System (ADS)

    Sviličić, Petra; Vučetić, 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.

  5. The climate variabilities of air temperature around the Korean Peninsula

    NASA Astrophysics Data System (ADS)

    Youn, Yong-Hoon

    2005-07-01

    In this study, changes in climatological conditions around the Korean Peninsula are estimated quantitatively using various types of high order statistical analyses. The temperature data collected from Incheon station have been analyzed for the assessment of the climate variation. According to our analysis, the climate changes observed over the Korean Peninsula for the last century are similar to the global observational data in many respects. First of all, the warming trend [+1.5°C (100 yr)-1] and the overall evolving pattern throughout the century are quite similar to each other. The temperature change in the Korean Peninsula is about two to three times larger than that of the global scale which may partially be ascribed to the influence of urbanization at mid and high latitudes. In this work, a new Winter Monsoon Index (WMI) is suggested based on the European continental scale circulation index (EU1) pattern. Our WMI is defined as the normalized sea level pressure (SLP) difference in the winter period between the centers of the East Sea and west of Lake Baikal in Siberia, the two eastern centers of the EU1 action patterns. A strong similarity is found between the time series of the WMI and surface air temperature at Incheon. The WMI has decreased gradually since the 1920s but has shifted to a rapid increasing trend in the last two decades; it was in fact accompanied by a weakening of the Siberian High and a decreasing of the northerly during winter. Our findings of the close correlations between the surface air temperature at Incheon and the WMI strongly indicate that our newly suggested index is unique and can be used as an efficient tool to predict climate variability in Korea.

  6. Amplification of surface temperature trends and variability in thetropical atmosphere

    SciTech Connect

    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.

    2005-08-11

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

  7. Soil Temperature Variability in Complex Terrain measured using Distributed a Fiber-Optic Distributed Temperature Sensing

    NASA Astrophysics Data System (ADS)

    Seyfried, M. S.; Link, T. E.

    2013-12-01

    Soil temperature (Ts) exerts critical environmental controls on hydrologic and biogeochemical processes. Rates of carbon cycling, mineral weathering, infiltration and snow melt are all influenced by Ts. Although broadly reflective of the climate, Ts is sensitive to local variations in cover (vegetative, litter, snow), topography (slope, aspect, position), and soil properties (texture, water content), resulting in a spatially and temporally complex distribution of Ts across the landscape. Understanding and quantifying the processes controlled by Ts requires an understanding of that distribution. Relatively few spatially distributed field Ts data exist, partly because traditional Ts data are point measurements. A relatively new technology, fiber optic distributed temperature system (FO-DTS), has the potential to provide such data but has not been rigorously evaluated in the context of remote, long term field research. We installed FO-DTS in a small experimental watershed in the Reynolds Creek Experimental Watershed (RCEW) in the Owyhee Mountains of SW Idaho. The watershed is characterized by complex terrain and a seasonal snow cover. Our objectives are to: (i) evaluate the applicability of fiber optic DTS to remote field environments and (ii) to describe the spatial and temporal variability of soil temperature in complex terrain influenced by a variable snow cover. We installed fiber optic cable at a depth of 10 cm in contrasting snow accumulation and topographic environments and monitored temperature along 750 m with DTS. We found that the DTS can provide accurate Ts data (+/- .4°C) that resolves Ts changes of about 0.03°C at a spatial scale of 1 m with occasional calibration under conditions with an ambient temperature range of 50°C. We note that there are site-specific limitations related cable installation and destruction by local fauna. The FO-DTS provide unique insight into the spatial and temporal variability of Ts in a landscape. We found strong seasonal trends in Ts variability controlled by snow cover and solar radiation as modified by topography. During periods of spatially continuous snow cover Ts was practically homogeneous throughout. In the absence of snow cover, Ts is highly variable, with most of the variability attributable to different topographic units defined by slope and aspect. During transition periods when snow melts out, Ts is highly variable within the watershed and within topographic units. The importance of accounting for these relatively small scale effects is underscored by the fact that the overall range of Ts in study area 600 m long is similar to that of the much large RCEW with 900 m elevation gradient.

  8. Sea surface temperature variability in the Colombian Basin, Caribbean Sea

    NASA Astrophysics Data System (ADS)

    Ruiz-Ochoa, Mauricio; Beier, Emilio; Bernal, Gladys; Barton, Eric Desmond

    2012-06-01

    Daily sea surface temperature (SST) data from the Advanced Very High Resolution Radiometer (AVHRR) database with ∼4 km of spatial resolution were analyzed for the period 1985-2009 in the Colombian Basin using harmonic and empirical orthogonal function (EOF) analysis. The data were compared with observational records in the Rosario Island National Park at 10 m depth (T10) from March 2003 to August 2005. SST values were higher than T10 from June to October (rainy season), but similar from December to February (dry season); both data sets have similar coefficient of variation. The mean SST distribution varies spatially, with minimum SST values in the coastal zone of La Guajira Peninsula and maximum values in the Darien and Mosquitos Gulfs. The seasonal variability explains up to 75% of the total variability in La Guajira, a high value compared with 40% in the Mosquitos Gulf. The most important feature of the splitting of SST variation into annual and semiannual harmonics in La Guajira is the relationship between their amplitudes. These are of the same order, which is not common in other ocean zones, where the semiannual component is only a small fraction of the annual dominated by the solar warming. The river water discharge, highest from August to November, produces low density surface water, reduces vertical mixing and limits the absorption of solar radiation to a thin surface layer, explaining the discrepancy between SST and T10 in the rainy season. The decomposition of the SST in EOFs indicated that the dominant mode of the basin is a uniform interannual variation in phase with the North Tropical Atlantic Index. The second mode, representing the variability of the Guajira upwelling, covaried strongly with the second mode of wind stress curl. The third mode reflected the role of the vertical atmospheric circulation cell associated with the Caribbean Low Level Jet off Central America.

  9. 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

  10. -30° C to 960° C Variable Temperature Blackbody (VTBB) Radiance Temperature Calibration Facility

    NASA Astrophysics Data System (ADS)

    Yuan, Z.; Wang, J.; Hao, X.; Wang, T.; Dong, W.

    2015-12-01

    A blackbody radiance temperature calibration facility (RTCF) has recently been established at the National Institute of Metrology, China, offering calibration and verification services for variable temperature blackbody (VTBB) radiation sources. The RTCF includes reference VTBBs in the range of -30° C to 960° C and consists of a stirred liquid bath blackbody of -30° C to 80° C and water, cesium, and sodium heat-pipe blackbodies spanning 50° C to 960° C. In addition, the facility is equipped with a set of radiation thermometers with different working wavelengths (or wavebands); these thermometers are used to transfer radiance temperatures from the reference to customers' VTBBs. Cavities with V-notch grooves in the inner surface have an estimated emissivity from 0.99986 to 0.99994. The temperature control stability and temperature uniformity of VTBBs are characterized. Furthermore, we test the difference between a cavity and thermometer well temperatures and compare the radiance temperatures of the Cs and Na heat-pipe blackbodies. The expanded uncertainty (k = 2) of VTBBs' radiance temperatures at 10 \\upmu m (8 \\upmu m to 14 \\upmu m) is evaluated from 0.016° C to 0.23° C. The facility has been used to calibrate and characterize customers' VTBBs.

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

    NASA Astrophysics Data System (ADS)

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

    2009-03-01

    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 converter provides this cooling. If the Stirling engine 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 engine. 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.

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

    SciTech Connect

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

    2009-03-16

    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 converter provides this cooling. If the Stirling engine 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 engine. 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 deg. C while the heat losses caused by the addition of the VCHP are 1.8 W.

  13. 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.

  14. 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.

  15. 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.

  16. Stratospheric temperature trends: impact of ozone variability and the QBO

    NASA Astrophysics Data System (ADS)

    Dall'Amico, Mauro; Gray, Lesley J.; Rosenlof, Karen H.; Scaife, Adam A.; Shine, Keith P.; Stott, Peter A.

    2010-02-01

    In most climate simulations used by the Intergovernmental Panel on Climate Change 2007 fourth assessment report, stratospheric processes are only poorly represented. For example, climatological or simple specifications of time-varying ozone concentrations are imposed and the quasi-biennial oscillation (QBO) of equatorial stratospheric zonal wind is absent. Here we investigate the impact of an improved stratospheric representation using two sets of perturbed simulations with the Hadley Centre coupled ocean atmosphere model HadGEM1 with natural and anthropogenic forcings for the 1979-2003 period. In the first set of simulations, the usual zonal mean ozone climatology with superimposed trends is replaced with a time series of observed zonal mean ozone distributions that includes interannual variability associated with the solar cycle, QBO and volcanic eruptions. In addition to this, the second set of perturbed simulations includes a scheme in which the stratospheric zonal wind in the tropics is relaxed to appropriate zonal mean values obtained from the ERA-40 re-analysis, thus forcing a QBO. Both of these changes are applied strictly to the stratosphere only. The improved ozone field results in an improved simulation of the stepwise temperature transitions observed in the lower stratosphere in the aftermath of the two major recent volcanic eruptions. The contribution of the solar cycle signal in the ozone field to this improved representation of the stepwise cooling is discussed. The improved ozone field and also the QBO result in an improved simulation of observed trends, both globally and at tropical latitudes. The Eulerian upwelling in the lower stratosphere in the equatorial region is enhanced by the improved ozone field and is affected by the QBO relaxation, yet neither induces a significant change in the upwelling trend.

  17. PROCESSES INFLUENCING VARIABILITY IN CAVE DRIP WATER TEMPERATURES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We have investigated five months of epikarst storage drip water temperatures along with surface air temperature and rainfall at a small waterfall in Cave Spring Caverns, Kentucky. Falling from about 4 m, water temperatures are measured within seconds of entering the cave passage with two minute, and...

  18. SPATIAL VARIABILITY OF REMOTELY SENSED SURFACE TEMPERATURE AT FIELD SCALE

    EPA Science Inventory

    Bare soil surface temperatures (BST) and crop canopy temperatures (CCT) were collected from a 1-ha field in central Arizona using an infrared thermometer to determine whether they were spatially correlated. The measurements were taken from a two-dimensional random sampling patter...

  19. Seasonal variability in Arctic temperatures during early Eocene time

    NASA Astrophysics Data System (ADS)

    Eberle, Jaelyn J.; Fricke, Henry C.; Humphrey, John D.; Hackett, Logan; Newbrey, Michael G.; Hutchison, J. Howard

    2010-08-01

    As a deep time analog for today's rapidly warming Arctic region, early Eocene (52-53 Ma) rock on Ellesmere Island in Canada's High Arctic (˜ 79°N.) preserves evidence of lush swamp forests inhabited by turtles, alligators, primates, tapirs, and hippo-like Coryphodon. Although the rich flora and fauna of the early Eocene Arctic imply warmer, wetter conditions than at present, the quantification of Eocene Arctic climate has been more elusive. By analyzing oxygen isotope ratios of biogenic phosphate from mammal, fish, and turtle fossils from a single locality on central Ellesmere Island, we infer early Eocene Arctic temperatures, including mean annual temperature (MAT) of ˜ 8 °C, mean annual range in temperature of ˜ 16.5-19 °C, warm month mean temperature of 19-20 °C, and cold month mean temperature of 0-3.5 °C. Our seasonal range in temperature is similar to the range in estimated MAT obtained using different proxies. In particular, relatively high estimates of early Eocene Arctic MAT and SST by others that are based upon the distribution of branched glycerol dialkyl glycerol tetraether (GDGT) membrane lipids in terrestrial soil bacteria and isoprenoid tetraether lipids in marine Crenarchaeota fall close to our warm month temperature, suggesting a bias towards summer values. From a paleontologic perspective, our temperature estimates verify that alligators and tortoises, by way of nearest living relative-based climatic inference, are viable paleoclimate proxies for mild, above-freezing year-round temperatures. Although for both of these reptilian groups, past temperature tolerances probably were greater than in living descendants.

  20. Seasonal variability in Arctic temperatures during the early Eocene

    NASA Astrophysics Data System (ADS)

    Eberle, J. J.; Fricke, H. C.; Humphrey, J.; Hackett, L.; Newbrey, M.; Hutchison, H.

    2009-12-01

    As a deep time analog for today’s rapidly warming Arctic region, early Eocene (~53 Ma) rocks on Ellesmere Island, Arctic Canada (~79° N.) preserve evidence of lush swamp forests inhabited by turtles, alligators, primates, tapirs, and hippo-like Coryphodon. Although the rich flora and fauna of the early Eocene Arctic imply warmer, wetter conditions that at present, quantitative estimates of Eocene Arctic climate are rare. By analyzing oxygen isotope ratios of biogenic phosphate from mammal, fish, and turtle fossils from a single locality on central Ellesmere Island, we provide estimates of early Eocene Arctic temperature, including mean annual temperature (MAT) of ~ 8° C, mean annual range in temperature (MART) of ~ 16.5° C, warm month mean temperature (WMMT) of 16 - 19° C, and cold month mean temperature (CMMT) of 0 - 1° C. Our seasonal range in temperature is similar to the range in estimated MAT obtained using different proxies. In particular, unusually high estimates of early Eocene Arctic MAT and sea surface temperature (SST) by others that are based upon the distribution of branched glycerol dialkyl glycerol tetraether (GDGT) membrane lipids in terrestrial soil bacteria and marine Crenarchaeota fall within our range of WMMT, suggesting a bias towards summer values. Consequently, caution should be taken when using these methods to infer MAT and SST that, in turn, are used to constrain climate models. From a paleontologic perspective, our temperature estimates verify that alligators and tortoises, by way of nearest living relative-based climatic inference, are viable paleoclimate proxies for mild, above-freezing year-round temperatures. Although in both of these reptiles, past temperature tolerances were greater than in their living descendants.

  1. Influence of Water and Temperature Stress on the Temperature Dependence of the Reappearance of Variable Fluorescence following Illumination

    PubMed Central

    Ferguson, David L.; Burke, John J.

    1991-01-01

    The temperature dependence of the rate and magnitude of the reappearance of photosystem II (PSII) variable fluorescence following illumination has been used to determine plant temperature optima. The present study was designed to determine the effect of a plant's environmental history on the thermal dependency of the reappearance of PSII variable fluorescence. In addition, this study further evaluated the usefulness of this fluorescence technique in identifying plant temperature optima. Laboratory and greenhouse grown potato (Solanum tuberosum L. cv “Norgold M”) plants had a thermal kinetic window between 15 and 25°C. The minimum apparent Km of NADH hydroxypyruvate reductase for NADH occurred at 20°C. This temperature was also the temperature providing maximal reappearance of variable fluorescence. Soybean (Glycine max [L.] Merrill cv “Wayne”) plants had a thermal kinetic window between 15 and 30°C with a minimum apparent Km at 25°C. Maximal reappearance of variable fluorescence was seen between 20 and 30°C. To determine if increasing environmental temperatures increased the temperature optimum provided from the fluorescence response curves, potato and soybean leaves from irrigated and dryland field grown plants were evaluated. Although the absolute levels of PSII variable fluorescence declined with increasing thermal stress, the temperature optimum of the dryland plants did not increase with increased exposure to elevated temperatures. Because of variability in the daily period of high temperature stress in the field, studies were initiated with tobacco plants grown in controlled environment chambers. The reappearance of PSII variable fluorescence in tobacco (Nicotiana tabacum L. cv “Wisconsin 38”) leaves that had experienced continuous leaf temperatures of 35°C for 8 days had the same 20°C optima as leaves from plants grown at room temperature. The results of this study suggest that the temperature optimum for the reappearance of variable fluorescence following illumination is not altered by the plant's previous exposure to variable environmental temperatures. These findings support the usefulness of this procedure for the rapid identification of a plant's temperature optimum. PMID:16668368

  2. 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.

  3. 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.

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

    NASA Astrophysics Data System (ADS)

    Elmallah, E. S.; Elsharkawy, S. G.

    2011-03-01

    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. Both power analysis and frequency distribution analysis are applied. The results show existence of Schwabe, Hale and Gleissberg cycles and declare that there are no critical thermal changes of climate in Egypt. It is concluded that the temperature changes during the past three decades are not only because of the human activity but the extraterrestrial impacts as well.

  5. 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.

  6. Temporal changes and variability in temperature series over Peninsular Malaysia

    NASA Astrophysics Data System (ADS)

    Suhaila, Jamaludin

    2015-02-01

    With the current concern over climate change, the descriptions on how temperature series changed over time are very useful. Annual mean temperature has been analyzed for several stations over Peninsular Malaysia. Non-parametric statistical techniques such as Mann-Kendall test and Theil-Sen slope estimation are used primarily for assessing the significance and detection of trends, while a nonparametric Pettitt's test and sequential Mann-Kendall test are adopted to detect any abrupt climate change. Statistically significance increasing trends for annual mean temperature are detected for almost all studied stations with the magnitude of significant trend varied from 0.02°C to 0.05°C per year. The results shows that climate over Peninsular Malaysia is getting warmer than before. In addition, the results of the abrupt changes in temperature using Pettitt's and sequential Mann-Kendall test reveal the beginning of trends which can be related to El Nino episodes that occur in Malaysia. In general, the analysis results can help local stakeholders and water managers to understand the risks and vulnerabilities related to climate change in terms of mean events in the region.

  7. Variable temperature NMR characterization of α-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 ( T1ρ) were measured as a function of temperature for a static sample of α-glycine. Both T1 and T1ρ 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 α- and γ-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 α-glycine within this temperature range.

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

    SciTech Connect

    Kim, C.-L.; Light, W.B.; Lee, W.W.-L.; Chambre, P.L.; Pigford, T.H.; Lawrence Berkeley Lab., CA )

    1988-09-01

    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.

  9. 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.

  10. Development and Evaluation of a Variable-Temperature Quadrupole Ion Trap Mass Spectrometer

    NASA Astrophysics Data System (ADS)

    Derkits, David; Wiseman, Alex; Snead, Russell F.; Dows, Martina; Harge, Jasmine; Lamp, Jared A.; Gronert, Scott

    2016-02-01

    A new, variable-temperature mass spectrometer system is described. By applying polyimide heating tape to the end-cap electrodes of a Bruker (Bremen, Germany) Esquire ion trap, it is possible to vary the effective temperature of the system between 40 and 100°C. The modification does not impact the operation of the ion trap and the heater can be used for extended periods without degradation of the system. The accuracy of the ion trap temperatures was assessed by examining two gas-phase equilibrium processes with known thermochemistry. In each case, the variable-temperature ion trap provided data that were in good accord with literature data, indicating the effective temperature in the ion trap environment was being successfully modulated by the changes in the set-point temperatures on the end-cap electrodes. The new design offers a convenient and effective way to convert commercial ion trap mass spectrometers into variable-temperature instruments.

  11. Amplification and dampening of soil respiration by changes in temperature variability

    USGS Publications Warehouse

    Sierra, C.A.; Harmon, M.E.; Thomann, E.; Perakis, S.S.; Loescher, H.W.

    2011-01-01

    Accelerated release of carbon from soils is one of the most important feed backs related to anthropogenically induced climate change. Studies addressing the mechanisms for soil carbon release through organic matter decomposition have focused on the effect of changes in the average temperature, with little attention to changes in temperature vari-ability. Anthropogenic activities are likely to modify both the average state and the variability of the climatic system; therefore, the effects of future warming on decomposition should not only focus on trends in the average temperature, but also variability expressed as a change of the probability distribution of temperature.Using analytical and numerical analyses we tested common relationships between temperature and respiration and found that the variability of temperature plays an important role determining respiration rates of soil organic matter. Changes in temperature variability, without changes in the average temperature, can affect the amount of carbon released through respiration over the long term. Furthermore, simultaneous changes in the average and variance of temperature can either amplify or dampen there release of carbon through soil respiration as climate regimes change. The effects depend on the degree of convexity of the relationship between temperature and respiration and the magnitude of the change in temperature variance. A potential consequence of this effect of variability would be higher respiration in regions where both the mean and variance of temperature are expected to increase, such as in some low latitude regions; and lower amounts of respiration where the average temperature is expected to increase and the variance to decrease, such as in northern high latitudes.

  12. Properties and mechanisms of Z2-FET at variable temperature

    NASA Astrophysics Data System (ADS)

    Dirani, Hassan El; Solaro, Yohann; Fonteneau, Pascal; Ferrari, Philippe; Cristoloveanu, Sorin

    2016-01-01

    This paper presents a systematic study of Z2-FET (Zero Subthreshold Swing and Zero Impact Ionization transistor) fabricated in advanced Fully Depleted Silicon On Insulator (FDSOI) 28 nm technology with Ultra-Thin Body and Buried Oxide (UTBB). It is a recent sharp-switching device that achieves remarkable performance in terms of leakage current and triggering control. The device features an extremely sharp on-switch, an adjustable triggering voltage (VON), and is considered for Electro-Static Discharge (ESD) protection. The operation principle relies on the modulation of electrons and holes injection barriers. Experimental results show the effect of low and high temperature on the output characteristics, triggering voltage and leakage current.

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

    PubMed

    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. PMID:23635240

  14. The absence of an Atlantic imprint on the multidecadal variability of wintertime European temperature.

    PubMed

    Yamamoto, Ayako; Palter, Jaime B

    2016-01-01

    Northern Hemisphere climate responds sensitively to multidecadal variability in North Atlantic sea surface temperature (SST). It is therefore surprising that an imprint of such variability is conspicuously absent in wintertime western European temperature, despite that Europe's climate is strongly influenced by its neighbouring ocean, where multidecadal variability in basin-average SST persists in all seasons. Here we trace the cause of this missing imprint to a dynamic anomaly of the atmospheric circulation that masks its thermodynamic response to SST anomalies. Specifically, differences in the pathways Lagrangian particles take to Europe during anomalous SST winters suppress the expected fluctuations in air-sea heat exchange accumulated along those trajectories. Because decadal variability in North Atlantic-average SST may be driven partly by the Atlantic Meridional Overturning Circulation (AMOC), the atmosphere's dynamical adjustment to this mode of variability may have important implications for the European wintertime temperature response to a projected twenty-first century AMOC decline. PMID:26975331

  15. The absence of an Atlantic imprint on the multidecadal variability of wintertime European temperature

    PubMed Central

    Yamamoto, Ayako; Palter, Jaime B.

    2016-01-01

    Northern Hemisphere climate responds sensitively to multidecadal variability in North Atlantic sea surface temperature (SST). It is therefore surprising that an imprint of such variability is conspicuously absent in wintertime western European temperature, despite that Europe's climate is strongly influenced by its neighbouring ocean, where multidecadal variability in basin-average SST persists in all seasons. Here we trace the cause of this missing imprint to a dynamic anomaly of the atmospheric circulation that masks its thermodynamic response to SST anomalies. Specifically, differences in the pathways Lagrangian particles take to Europe during anomalous SST winters suppress the expected fluctuations in air–sea heat exchange accumulated along those trajectories. Because decadal variability in North Atlantic-average SST may be driven partly by the Atlantic Meridional Overturning Circulation (AMOC), the atmosphere's dynamical adjustment to this mode of variability may have important implications for the European wintertime temperature response to a projected twenty-first century AMOC decline. PMID:26975331

  16. The absence of an Atlantic imprint on the multidecadal variability of wintertime European temperature

    NASA Astrophysics Data System (ADS)

    Yamamoto, Ayako; Palter, Jaime B.

    2016-03-01

    Northern Hemisphere climate responds sensitively to multidecadal variability in North Atlantic sea surface temperature (SST). It is therefore surprising that an imprint of such variability is conspicuously absent in wintertime western European temperature, despite that Europe's climate is strongly influenced by its neighbouring ocean, where multidecadal variability in basin-average SST persists in all seasons. Here we trace the cause of this missing imprint to a dynamic anomaly of the atmospheric circulation that masks its thermodynamic response to SST anomalies. Specifically, differences in the pathways Lagrangian particles take to Europe during anomalous SST winters suppress the expected fluctuations in air-sea heat exchange accumulated along those trajectories. Because decadal variability in North Atlantic-average SST may be driven partly by the Atlantic Meridional Overturning Circulation (AMOC), the atmosphere's dynamical adjustment to this mode of variability may have important implications for the European wintertime temperature response to a projected twenty-first century AMOC decline.

  17. Semi-stationary measurement as a tool to refine understanding of the soil temperature spatial variability

    NASA Astrophysics Data System (ADS)

    Lehnert, Michal; Vysoudil, Miroslav; Kladivo, Petr

    2015-10-01

    Using data obtained by soil temperature measurement at stations in the Metropolitan Station Network in Olomouc, extensive semi-stationary measurement was implemented to study the spatial variability of the soil temperature. With the development of the research and computer technology, the study of the temperature is not limited by the complexity of the processes determining the soil temperature, but by the lack of spatial data. This study presents simple semi-stationary soil temperature measurement methods, which can contribute to the study of the spatial variability of soil temperature. By semi-stationary measurement, it is possible to determine the average soil temperature with high accuracy and the minimum soil temperature with sufficient accuracy at a depth of 20 cm. It was proven that the spatial variability of the minimum soil temperature under grass at a depth of 20 cm can reach up to several degrees Celsius at the regional level, more than 1°C at the local level, and tenths of °C at the sublocal level. Consequently, the standard stationary measurement of the soil temperature can be regarded as representative only for a very limited area. Semi-stationary soil temperature measurement is, therefore, an important tool for further development of soil temperature research.

  18. 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.

  19. Reduced Surface Ocean Temperature Variability in the Eastern Equatorial Pacific During the Late Glacial Maximum

    NASA Astrophysics Data System (ADS)

    Ford, H. L.; Ravelo, A. C.; Polissar, P. J.

    2012-12-01

    El Niño-Southern Oscillation is the largest source of global interannual variability with far-reaching climatic effects. Climate model simulations of future warming exhibit widely divergent behavior indicating an incomplete understanding of the factors that dictate tropical climate variability. Generating records of past tropical Pacific variability during times with different climate states is one approach to deepening our understanding of tropical climate change processes and improving predictions of future change. Here we reconstruct tropical Pacific ocean variability from the Last Glacial Maximum (LGM) and from the Holocene at ODP Sites 806 and 849, located in the western equatorial Pacific (WEP) warm pool and eastern equatorial Pacific (EEP) cold tongue, respectively. We reconstruct ocean temperature variability using the intra-sample distribution of Mg/Ca values from individual foraminifera. Sea surface temperature variability is reconstructed from individual specimens of G. sacculifer analyzed for Mg/Ca values with laser ablation ICP-MS (Photon Machines Analyte.193 with HelEx sample cell coupled with a Thermo ElementXS ICP-MS, LA-ICP-MS). Subsurface temperature variability is reconstructed from individual specimens of G. tumida analyzed for Mg/Ca values by ICP-OES. Our results indicate that the cooling of last glacial maximum SSTs was greater in the WEP compared to the EEP. Furthermore, we show this cooling is not an artifact of changes in seasonal or interannual foraminiferal fluxes, but rather, reflects overall cooler temperatures and thus changes in seasonal/interannual heat fluxes. At Site 806 in the WEP, variability during the Holocene and LGM was similar, suggesting the cooling was a direct response to pCO2-radiative forcing. In contrast, at Site 849, sea surface temperature variability during the LGM was greatly diminished in comparison to the Holocene suggesting reduced ENSO and seasonal variability. Therefore conditions in the EEP responded to both pCO2-radiative and dynamic oceanic-atmospheric forcing. Subsurface conditions were also different in the LGM compared to the Holocene. In the WEP, the subsurface temperature was cooler in the LGM, possibly reflecting changes in the upper ocean thermal structure and mid-latitude source water regions. In the EEP, the subsurface temperatures were also cooler, but additionally exhibited higher variability in the LGM compared to the Holocene. We interpret this subsurface data to reflect enhanced seasonality in the thermocline depth driven by enhanced seasonal variations in the cross-basin pressure gradients and winds stress. Our results show that by quantifying the distribution and variability of past ocean temperatures we can differentiate between the mechanisms responsible for temperature change.

  20. 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.

  1. EFFECT OF VARIABLE TEMPERATURE ON THE INFECTION FREQUENCY OF SPHAEROTHECA MACULARIS ON HUMULUS LUPULUS.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effect of variable temperature on the infection frequency of Sphaerotheca macularis (sym. S. humuli) on Humulus lupulus L. (Hops) was investigated. Potted 'Symphony' hop plants were inoculated and exposed to different supra-optimal temperature regimes for varying amounts of time. Infection...

  2. Spatial patterns of historical temperature variability: Global correlations using spectral and wavelet techniques

    SciTech Connect

    Park, J.

    1995-12-31

    In order to assess man`s impact on global climate, we need to understand natural climate variability more fully. Using 100 years of global temperature data, we have developed time-series methods that identify coherent spatio-temporal {open_quotes}modes{close_quotes} of temperature variability e.g., El Nino-Southern Oscillation (ENSO) cycles. Methods based on multiple-taper spectral analysis estimate the correlated temperature variability within narrow frequency bands. Methods based on a multiple wavelet analysis identify short-term global temperature {open_quotes}events{close_quotes} on a range of time scales. We assess the statistical significance of narrow-band and event correlations from Monte Carlo confidence limits, which are derived from stochastic variations of uncorrelated white-noise time series. Significant patterns of variability with 2.8 to 5.7 year duration exhibit the characteristic ENSO pattern: warming in the tropics, followed by temperature excursions in middle latitudes. An interdecadal mode (15-18 years) appears to represent long-term ENSO variability, an interpretation supported by the persistence of warm Pacific Ocean surface water in the decade after the large 1982-3 El Nino episode. The interdecadal mode appears to explain much of the anomalous global warmth of the 1980s. North Atlantic variability dominates quasi-biennial (2.2 years) and decadal (7-12 years) modes.

  3. Kiloampere, Variable-Temperature, Critical-Current Measurements of High-Field Superconductors

    PubMed Central

    Goodrich, LF; Cheggour, N; Stauffer, TC; Filla, BJ; Lu, XF

    2013-01-01

    We review variable-temperature, transport critical-current (Ic) measurements made on commercial superconductors over a range of critical currents from less than 0.1 A to about 1 kA. We have developed and used a number of systems to make these measurements over the last 15 years. Two exemplary variable-temperature systems with coil sample geometries will be described: a probe that is only variable-temperature and a probe that is variable-temperature and variable-strain. The most significant challenge for these measurements is temperature stability, since large amounts of heat can be generated by the flow of high current through the resistive sample fixture. Therefore, a significant portion of this review is focused on the reduction of temperature errors to less than ±0.05 K in such measurements. A key feature of our system is a pre-regulator that converts a flow of liquid helium to gas and heats the gas to a temperature close to the target sample temperature. The pre-regulator is not in close proximity to the sample and it is controlled independently of the sample temperature. This allows us to independently control the total cooling power, and thereby fine tune the sample cooling power at any sample temperature. The same general temperature-control philosophy is used in all of our variable-temperature systems, but the addition of another variable, such as strain, forces compromises in design and results in some differences in operation and protocol. These aspects are analyzed to assess the extent to which the protocols for our systems might be generalized to other systems at other laboratories. Our approach to variable-temperature measurements is also placed in the general context of measurement-system design, and the perceived advantages and disadvantages of design choices are presented. To verify the accuracy of the variable-temperature measurements, we compared critical-current values obtained on a specimen immersed in liquid helium (“liquid” or Ic liq) at 5 K to those measured on the same specimen in flowing helium gas (“gas” or Ic gas) at the same temperature. These comparisons indicate the temperature control is effective over the superconducting wire length between the voltage taps, and this condition is valid for all types of sample investigated, including Nb-Ti, Nb3Sn, and MgB2 wires. The liquid/gas comparisons are used to study the variable-temperature measurement protocol that was necessary to obtain the “correct” critical current, which was assumed to be the Ic liq. We also calibrated the magnetoresistance effect of resistive thermometers for temperatures from 4 K to 35 K and magnetic fields from 0 T to 16 T. This calibration reduces systematic errors in the variable-temperature data, but it does not affect the liquid/gas comparison since the same thermometers are used in both cases. PMID:26401435

  4. Kiloampere, Variable-Temperature, Critical-Current Measurements of High-Field Superconductors.

    PubMed

    Goodrich, L F; Cheggour, N; Stauffer, T C; Filla, B J; Lu, X F

    2013-01-01

    We review variable-temperature, transport critical-current (I c) measurements made on commercial superconductors over a range of critical currents from less than 0.1 A to about 1 kA. We have developed and used a number of systems to make these measurements over the last 15 years. Two exemplary variable-temperature systems with coil sample geometries will be described: a probe that is only variable-temperature and a probe that is variable-temperature and variable-strain. The most significant challenge for these measurements is temperature stability, since large amounts of heat can be generated by the flow of high current through the resistive sample fixture. Therefore, a significant portion of this review is focused on the reduction of temperature errors to less than ±0.05 K in such measurements. A key feature of our system is a pre-regulator that converts a flow of liquid helium to gas and heats the gas to a temperature close to the target sample temperature. The pre-regulator is not in close proximity to the sample and it is controlled independently of the sample temperature. This allows us to independently control the total cooling power, and thereby fine tune the sample cooling power at any sample temperature. The same general temperature-control philosophy is used in all of our variable-temperature systems, but the addition of another variable, such as strain, forces compromises in design and results in some differences in operation and protocol. These aspects are analyzed to assess the extent to which the protocols for our systems might be generalized to other systems at other laboratories. Our approach to variable-temperature measurements is also placed in the general context of measurement-system design, and the perceived advantages and disadvantages of design choices are presented. To verify the accuracy of the variable-temperature measurements, we compared critical-current values obtained on a specimen immersed in liquid helium ("liquid" or I c liq) at 5 K to those measured on the same specimen in flowing helium gas ("gas" or I c gas) at the same temperature. These comparisons indicate the temperature control is effective over the superconducting wire length between the voltage taps, and this condition is valid for all types of sample investigated, including Nb-Ti, Nb3Sn, and MgB2 wires. The liquid/gas comparisons are used to study the variable-temperature measurement protocol that was necessary to obtain the "correct" critical current, which was assumed to be the I c liq. We also calibrated the magnetoresistance effect of resistive thermometers for temperatures from 4 K to 35 K and magnetic fields from 0 T to 16 T. This calibration reduces systematic errors in the variable-temperature data, but it does not affect the liquid/gas comparison since the same thermometers are used in both cases. PMID:26401435

  5. Impacts of temperature and its variability on mortality in New England

    NASA Astrophysics Data System (ADS)

    Shi, Liuhua; Kloog, Itai; Zanobetti, Antonella; Liu, Pengfei; Schwartz, Joel D.

    2015-11-01

    Rapid build-up of greenhouse gases is expected to increase Earth’s mean surface temperature, with unclear effects on temperature variability. This makes understanding the direct effects of a changing climate on human health more urgent. However, the effects of prolonged exposures to variable temperatures, which are important for understanding the public health burden, are unclear. Here we demonstrate that long-term survival was significantly associated with both seasonal mean values and standard deviations of temperature among the Medicare population (aged 65+) in New England, and break that down into long-term contrasts between ZIP codes and annual anomalies. A rise in summer mean temperature of 1 °C was associated with a 1.0% higher death rate, whereas an increase in winter mean temperature corresponded to a 0.6% decrease in mortality. Increases in standard deviations of temperature for both summer and winter were harmful. The increased mortality in warmer summers was entirely due to anomalies, whereas it was long-term average differences in the standard deviation of summer temperatures across ZIP codes that drove the increased risk. For future climate scenarios, seasonal mean temperatures may in part account for the public health burden, but the excess public health risk of climate change may also stem from changes of within-season temperature variability.

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

    NASA Astrophysics Data System (ADS)

    Way, Robert G.; Viau, Andre E.

    2015-08-01

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

  7. Daily and Interannual Variability of Air Temperature and Precipitation As Agricultural Factor

    NASA Astrophysics Data System (ADS)

    Sourkova, G.; Pona, C.

    The problem investigated concerns wheat growing process sensitivity to the changes in climate variability. For the sensitivity analysis five CERES-model runs are held for three stations in Italy: Decimomannu (Sardinia), Brindisi (Apulia) and Ghedi (Padana valley, Veneto). The only difference between these five experiments for each station is a weather input. All five weather inputs for each location are simulated by weather generator WXGEN. First run ("base") is forced by weather input having tempera- ture and precipitation variance equal to the present-day values (1960-1990). Then two crop simulations are made with changed "base" interannual variance of monthly to- tal precipitation by multiplicative factors 0.5 and 2. Temperature variability remains unchanged. Last two model runs are carried out with daily halved and doubled temper- ature variance, precipitation variability is the same as in "base" simulation. Investiga- tion showed that doubled precipitation variability is accompanied at all three locations by the largest amounts of yield variability for all five scenarios. Decreased precipi- tation variability is followed by yield decline and, at the same time the amplitude of yield change is the least compared with other forcings. Decreasing of precipitation variability results in noticeably raised harvest index for the years of minimum yield. For Decimomannu and Brindisi it is almost equal to that of the maximum yield years. In general, more significantly expressed response of the yield amounts occurs for pre- cipitation variability forcings. The influence of temperature variability changes seems to be less for all three locations.

  8. 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.

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

    SciTech Connect

    Steurer, Wolfram Gross, Leo; Schlittler, Reto R.; Meyer, Gerhard

    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.

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

    PubMed Central

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

    2015-01-01

    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

  11. 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

  12. Ocean surface temperature variability: Large model–data differences at decadal and longer periods

    PubMed Central

    Laepple, Thomas; Huybers, Peter

    2014-01-01

    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

  13. Recent Climate Variability in Antarctica from Satellite-derived Temperature Data

    NASA Technical Reports Server (NTRS)

    Schneider, David P.; Steig, Eric J.; Comiso, Josefino C.

    2004-01-01

    Recent Antarctic climate variability on month-to-month to interannual time scales is assessed through joint analysis of surface temperatures from satellite thermal infrared observations (T(sub IR)) and passive microwave brightness temperatures (T(sub B)). Although Tw data are limited to clear-sky conditions and T(sub B) data are a product of the temperature and emissivity of the upper approx. 1m of snow, the two data sets share significant covariance. This covariance is largely explained by three empirical modes, which illustrate the spatial and temporal variability of Antarctic surface temperatures. T(sub B) variations are damped compared to TIR variations, as determined by the period of the temperature forcing and the microwave emission depth; however, microwave emissivity does not vary significantly in time. Comparison of the temperature modes with Southern Hemisphere (SH) 500-hPa geopotential height anomalies demonstrates that Antarctic temperature anomalies are predominantly controlled by the principal patterns of SH atmospheric circulation. The leading surface temperature mode strongly correlates with the Southern Annular Mode (SAM) in geopotential height. The second temperature mode reflects the combined influences of the zonal wavenumber-3 and Pacific South American (PSA) patterns in 500-hPa height on month-to-month timescales. ENSO variability projects onto this mode on interannual timescales, but is not by itself a good predictor of Antarctic temperature anomalies. The third temperature mode explains winter warming trends, which may be caused by blocking events, over a large region of the East Antarctic plateau. These results help to place recent climate changes in the context of Antarctica's background climate variability and will aid in the interpretation of ice core paleoclimate records.

  14. 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.

  15. Regions of significant influence on unforced global mean surface air temperature variability in climate models

    NASA Astrophysics Data System (ADS)

    Brown, Patrick T.; Li, Wenhong; Xie, Shang-Ping

    2015-01-01

    document the geographic regions where local variability is most associated with unforced global mean surface air temperature (GMT) variability in Coupled Model Intercomparison Project Phase 5 coupled global climate models (GCMs) at both the subdecadal and interdecadal timescales. For this purpose, Regions of Significant Influence on GMT are defined as locations that have a statistically significant correlation between local surface air temperature (SAT) and GMT (with a regression slope greater than 1), and where local SAT variation leads GMT variation in time. In both GCMs and observations, subdecadal timescale GMT variability is most associated with SAT variation over the eastern equatorial Pacific. At the interdecadal timescale, GMT variability is also linked with SAT variation over the Pacific in many GCMs, but the particular spatial patterns are GCM dependent, and several GCMs indicate a primary association between GMT and SAT over the Southern Ocean. We find that it is difficult to validate GCM behavior at the interdecadal timescale because the pattern derived from observations is highly depended on the method used to remove the forced variability from the record. The magnitude of observed GMT variability is near the ensemble median at the subdecadal timescale but well above the median at the interdecadal timescale. GCMs with a stronger subdecadal relationship between GMT and SAT over the Pacific tend to have more variable subdecadal GMT while GCMs with a stronger interdecadal relationship between GMT and SAT over parts of the Southern Ocean tend to have more variable GMT.

  16. Simulating soybean canopy temperature as affected by weather variables and soil water potential

    NASA Technical Reports Server (NTRS)

    Choudhury, B. J.

    1982-01-01

    Hourly weather data for several clear sky days during summer at Phoenix and Baltimore which covered a wide range of variables were used with a plant atmosphere model to simulate soybean (Glycine max L.) leaf water potential, stomatal resistance and canopy temperature at various soil water potentials. The air and dew point temperatures were found to be the significant weather variables affecting the canopy temperatures. Under identical weather conditions, the model gives a lower canopy temperature for a soybean crop with a higher rooting density. A knowledge of crop rooting density, in addition to air and dew point temperatures is needed in interpreting infrared radiometric observations for soil water status. The observed dependence of stomatal resistance on the vapor pressure deficit and soil water potential is fairly well represented. Analysis of the simulated leaf water potentials indicates overestimation, possibly due to differences in the cultivars.

  17. 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 Δ LF/HF ratio, and increased Δ 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.

  18. A temperature rise reduces trial-to-trial variability of locust auditory neuron responses.

    PubMed

    Eberhard, Monika J B; Schleimer, Jan-Hendrik; Schreiber, Susanne; Ronacher, Bernhard

    2015-09-01

    The neurophysiology of ectothermic animals, such as insects, is affected by environmental temperature, as their body temperature fluctuates with ambient conditions. Changes in temperature alter properties of neurons and, consequently, have an impact on the processing of information. Nevertheless, nervous system function is often maintained over a broad temperature range, exhibiting a surprising robustness to variations in temperature. A special problem arises for acoustically communicating insects, as in these animals mate recognition and mate localization typically rely on the decoding of fast amplitude modulations in calling and courtship songs. In the auditory periphery, however, temporal resolution is constrained by intrinsic neuronal noise. Such noise predominantly arises from the stochasticity of ion channel gating and potentially impairs the processing of sensory signals. On the basis of intracellular recordings of locust auditory neurons, we show that intrinsic neuronal variability on the level of spikes is reduced with increasing temperature. We use a detailed mathematical model including stochastic ion channel gating to shed light on the underlying biophysical mechanisms in auditory receptor neurons: because of a redistribution of channel-induced current noise toward higher frequencies and specifics of the temperature dependence of the membrane impedance, membrane potential noise is indeed reduced at higher temperatures. This finding holds under generic conditions and physiologically plausible assumptions on the temperature dependence of the channels' kinetics and peak conductances. We demonstrate that the identified mechanism also can explain the experimentally observed reduction of spike timing variability at higher temperatures. PMID:26041833

  19. 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.

  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. Intensity of climate variability derived from the satellite and MERRA reanalysis temperatures: AO, ENSO, and QBO

    NASA Astrophysics Data System (ADS)

    Yoo, Jung-Moon; Won, Young-In; Jeong, Myeong-Jae; Kim, Kyu-Myong; Shin, Dong-Bin; Lee, Yu-Ri; Cho, Young-Jun

    2013-04-01

    Satellite measurements (Atmospheric InfraRed Sounder/Advanced Microwave Sounding Unit-A, MODerate resolution Imaging Spectroradiometer) and the Modern Era Retrospective-analysis for Research and Applications (MERRA) reanalysis have been utilized to analyze the relative influence of the climate variability (AO: Arctic Oscillation, ENSO: El Niño-Southern Oscillation, QBO: Quasi-Biennial Oscillation) on the zonal-mean temperature and wind variations over the globe from September 2002 to August 2011. We also extended the usage of MERRA data for the period of 1979-2011; furthermore, three climate indices of AO, NINO3.4, and QBO were used as the corresponding climate indicators. The correlations between the temperature anomalies and the climate indices indicate that the tropospheric temperature variability in the mid-latitude (30-60N) linked to both AO and ENSO has been more pronounced over ocean than over land. However, the low stratospheric temperature variability in the mid-latitude is mainly associated with ENSO and QBO. The north-south symmetric patterns over the globe are seen in the wind anomaly distributions for ENSO and QBO, but not for AO. The ENSO events are globally vigorous but also localized during the recent 9 years compared with those based on the period of 1979-2011. The tropospheric warming and stratospheric cooling phenomena during this period are more remarkable in the recent 9 years, although according to IPCC (2012). their linkage to the ENSO variability is still uncertain. The ENSO is found to have more significant impact on the tropospheric and low stratosphere temperature variability over the tropics in the recent period, consistent with more active zonal wind meridional circulations. The discrepancies between satellite observations and MERRA are also discussed. The estimated relative impact of the three major concurrent large-scale climate phenomena on regional temperature variability can be of great use in its long-term predictability.

  2. Internal and Forced Low-Frequency Surface Temperature Variability at Global and Regional Scales

    NASA Astrophysics Data System (ADS)

    Mann, M. E.; Steinman, B. A.; Miller, S. K.

    2014-12-01

    There is evidence for internal models of decadal and multidecadal surface temperature variability that possess relatively narrowband spectral signatures. Among these are the so-called Atlantic Multidecadal Oscillation ("AMO") and Pacific Decadal Oscillation ("PDO"). Separating these internal variability components from long-term forced temperature changes, however, is a non-trivial task. We apply a semi-empirical approach that combines climate observations and model-simulations to estimate Atlantic- and Pacific-based internal multidecadal variability (termed 'AMO' and 'PMO', respectively). Using analyses of coupled global climate model simulations, we show that our approach correctly identifies the internal variability components, while several alternative approaches overestimate and misidentify these components and their contribution to hemispheric mean temperatures. Using our method, the AMO and PMO are found to project in nearly equal proportion onto internal multidecadal variability in Northern Hemisphere mean temperature (termed 'NMO'). A recent NMO cooling trend which contributes to the slowdown or "false pause" in warming of the past decade is seen to reflect a competition between a modest positive peak in the AMO and a substantially negative-trending PMO.

  3. Sea surface temperature variability in the southwest tropical Pacific since AD 1649

    NASA Astrophysics Data System (ADS)

    Delong, Kristine L.; Quinn, Terrence M.; Taylor, Frederick W.; Lin, Ke; Shen, Chuan-Chou

    2012-11-01

    A prime focus of research is differentiating the contributions of natural climate variability from those that are anthropogenically forced, especially as it relates to climate prediction. The short length of instrumental records, particularly from the South Pacific, hampers this research, specifically for investigations of decadal to centennial scale variability. Here we present a sea surface temperature (SST) reconstruction derived from highly reproducible records of strontium-to-calcium ratios (Sr/Ca) in corals from New Caledonia to investigate natural SST variability in the southwest tropical Pacific from AD 1649-1999. Our results reveal periods of warmer and colder temperatures of the order of decades during the Little Ice Age that do not correspond to long-term variations in solar irradiance or the 11-year sunspot cycle. We suggest that solar variability does not explain decadal to centennial scale SST variability in reconstructions from the southwest tropical Pacific. Our SST reconstruction covaries with the Southern Hemisphere Pacific decadal oscillation and the South Pacific decadal oscillation, from which SST anomalies in the southwest Pacific are linked to precipitation anomalies in the western tropical Pacific. We find that decadal scale SST variability has changed in strength and periodicity after 1893, suggesting a shift in natural variability for this location.

  4. Understanding and Modeling Rainfall and Temperature Variability in Ciliwung Watershed, Jakarta, Indonesia

    NASA Astrophysics Data System (ADS)

    Yanto, M.; Rajagopalan, B.; Zagona, E. A.

    2014-12-01

    Rainfall derived flow from the Ciliwung watershed is the main source of water supply for Jakarta, the capital city of Indonesia. In recent decades this region has experienced substantial increase in variability - especially with intense rainfall events during wet season (Nov-Apr) causing severe flood damage and low rainfall seasons resulting in water shortages. On the other hand, higher evaporation rates driven by increasing air temperatures contribute significantly to water losses in this region. Thus, understanding the inter-annual and multi-decadal variability of rainfall and temperature in the basin is important for efficient water resources management. To this end, the objective of this research is to investigate the relationship between large scale climate variables and basin hydroclimatology and to use these in statistical models for potential skillful prediction. We perform Principal Component Analysis on the space-time rainfall and temperature fields to identify dominant modes of variability. The modes are then related to large scale climate fields such as sea surface temperatures, sea level pressures, etc. to identify regions of high correlation and consequently, the potential physical mechanisms and predictors such as El Nino Southern Oscillation (ENSO) are isolated. Subsequently, we develop a statistical prediction model for the wet season (Nov-Apr) rainfall and temperature based on the climate predictors developed from the above diagnostics. We find significant prediction skill, improving the prospects for efficient water resources management.

  5. Independent component analysis of local-scale temporal variability in sediment-water interface temperature

    NASA Astrophysics Data System (ADS)

    Middleton, M. A.; Whitfield, P. H.; Allen, D. M.

    2015-12-01

    Temperature recorded at the sediment-water interface has been identified as a valuable tracer for understanding groundwater-surface water interactions. However, factors contributing to the variability in temperatures can be difficult to distinguish. In this study, the temporal variability in daily temperatures at the sediment-water interface is evaluated for a 40 m reach of a coastal stream using Independent Component Analysis (ICA). ICA separation is used to identify three independent temperature components within the reach for each of four summer periods (2008-2011). Extracted temperature signals correlate with stream discharge, estimated streambed temperature, and groundwater level, but the strength of the correlations varies from summer to summer. Overall, variations in the temperature signals have clearer separation in summers with lower stream discharge and greater stream temperature ranges. Surface heating from solar radiation is the dominant factor influencing the sediment-water interface temperature in most years, but there is evidence that thermal exchanges are taking place other than at the air-water interface. These exchanges take place at the sediment-water interface, and the correlation with groundwater levels indicates that these heat exchanges are associated with groundwater inflow. This study demonstrates that ICA can be used effectively to aid in identifying component signals in environmental applications of small spatial scale.

  6. 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.

  7. Deglacial Subsurface Temperature Change in the Tropical North Atlantic Linked to Atlantic Meridional Overturning Circulation Variability

    NASA Astrophysics Data System (ADS)

    Schmidt, M. W.; Chang, P.; Otto-Bliesner, B. L.

    2010-12-01

    Coupled ocean-atmosphere modeling experiments indicate that Atlantic meridional overturning circulation (AMOC) variability is tightly coupled to abrupt tropical North Atlantic (TNA) climate change through both atmospheric and oceanic processes (Zhang, 2007; Chang et al., 2008; and Chiang et al., 2008). While a slowdown of AMOC in these experiments results in an atmospheric-induced surface cooling in the entire TNA, the subsurface experiences an even larger warming due to rapid reorganizations of ocean circulation patterns (Wan et al., 2009). In addition, observational records of detrended 20th century ocean temperature and salinity variability show a strong anticorrelation between surface cooling and subsurface warming in the TNA over the past several decades, suggesting changing vertical temperature gradients in this region may be a distinct fingerprint of AMOC variability (Zhang 2007). In order to test the hypothesis that subsurface temperature change in the TNA is coupled to AMOC variability across abrupt climate events over the last deglacial, we reconstructed high-resolution Mg/Ca-temperature and δ18O records from both surface (G. ruber) and sub-thermocline dwelling (G. truncatulinoides, 350-500 m depth and G. crassaformis, 450-580 m) planktonic foraminifera in the southern Caribbean Sea sediment core VM12-107 (11.33oN, 66.63oW; 1079 m; 18 cm/kyr sedimentation rate). Sea surface temperatures indicate a gradual warming in the TNA starting at ~19 kyr BP with small cold reversals of ~1.5oC during Heinrich Event 1 (H1) and the Younger Dryas (YD). In contrast, last glacial maximum subsurface temperatures were as much as 2.5oC warmer than Late Holocene values and H1 and the YD are marked by the warmest subsurface temperatures characterized by abrupt temperature increases as large as 4-5oC. Furthermore, a comparison of our subsurface temperature record with the Bermuda Rise 231Pa/230Th proxy record of AMOC variability (McManus et al., 2004) indicates a strong correlation between periods of reduced AMOC and subsurface warming in the TNA. Our results suggest that western TNA subsurface temperature change is a sensitive indicator of AMOC strength with the potential to determine AMOC variability during marine isotope stage 3.

  8. Temporal variability of thermal refuges and water temperature patterns in an Atlantic salmon river

    NASA Astrophysics Data System (ADS)

    Dugdale, S.; Bergeron, N.; St-Hilaire, A.

    2013-12-01

    River basins in northern latitudes are predicted to experience increased water temperatures under future climate change. This will have a negative impact on most salmonid populations which are highly intolerant of temperatures in excess of 23° C. In response to summer heat stress, salmonids thermoregulate in discrete units of cold water. Termed thermal refuges, these are of great significance to the ability of salmon and trout to survive increased water temperatures. Although previous research has documented links between the spatial patterns of thermal refuges and salmonid distribution and behaviour, the temporal variability of these cold water units has never been studied. In this investigation, airborne thermal infrared (TIR) imagery acquired six times between 2009 and 2011 was used to characterise temporal variability of thermal refuges and broader scale patterns of water temperature in the Rivière Ouelle, an Atlantic salmon river in Québec, Canada. Thermal refuges detected from TIR imagery were classified into a series of categories, revealing notable inter-survey variability between the absolute counts of each refuge type. Broader-scale longitudinal temperature profiles of river temperature were also extracted. Temporal variability in the absolute counts of lateral groundwater seeps (the most frequently observed thermal refuge class) was shown to correlate strongly with long duration hydrometeorological metrics such as seasonal mean discharge (R2 = 0.94, p < 0.01). Conversely, thermal refuges resulting from cold water tributaries were more temporally stable. Downstream temperature complexity was shown to correlate best with short duration metrics such as cumulative precipitation depth within a 5-day period prior to each survey (R2 = 0.90, p < 0.01). This study is the first of its kind to link thermal refuge dynamics and water temperature patterns to hydrometeorological conditions and may offer valuable insights into how changing hydrometeorological regimes could influence these important cold water units in the future.

  9. 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

    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.

  10. 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. PMID:26074665

  11. Temperature Values Variability in Piezoelectric Implant Site Preparation: Differences between Cortical and Corticocancellous Bovine Bone

    PubMed Central

    Lamazza, Luca; Garreffa, Girolamo; Laurito, Domenica; Lollobrigida, Marco; Palmieri, Luigi; De Biase, Alberto

    2016-01-01

    Purpose. Various parameters can influence temperature rise and detection during implant site preparation. The aim of this study is to investigate local temperature values in cortical and corticocancellous bovine bone during early stages of piezoelectric implant site preparation. Materials and Methods. 20 osteotomies were performed using a diamond tip (IM1s, Mectron Medical Technology, Carasco, Italy) on two different types of bovine bone samples, cortical and corticocancellous, respectively. A standardized protocol was designed to provide constant working conditions. Temperatures were measured in real time at a fixed position by a fiber optic thermometer. Results. Significantly higher drilling time (154.90 sec versus 99.00 sec; p < 0.0001) and temperatures (39.26°C versus 34.73°C; p = 0.043) were observed in the cortical group compared to the corticocancellous group. A remarkable variability of results characterized the corticocancellous blocks as compared to the blocks of pure cortical bone. Conclusion. Bone samples can influence heat generation during in vitro implant site preparation. When compared to cortical bone, corticocancellous samples present more variability in temperature values. Even controlling most experimental factors, the impact of bone samples still remains one of the main causes of temperature variability. PMID:27110567

  12. Temperature Values Variability in Piezoelectric Implant Site Preparation: Differences between Cortical and Corticocancellous Bovine Bone.

    PubMed

    Lamazza, Luca; Garreffa, Girolamo; Laurito, Domenica; Lollobrigida, Marco; Palmieri, Luigi; De Biase, Alberto

    2016-01-01

    Purpose. Various parameters can influence temperature rise and detection during implant site preparation. The aim of this study is to investigate local temperature values in cortical and corticocancellous bovine bone during early stages of piezoelectric implant site preparation. Materials and Methods. 20 osteotomies were performed using a diamond tip (IM1s, Mectron Medical Technology, Carasco, Italy) on two different types of bovine bone samples, cortical and corticocancellous, respectively. A standardized protocol was designed to provide constant working conditions. Temperatures were measured in real time at a fixed position by a fiber optic thermometer. Results. Significantly higher drilling time (154.90 sec versus 99.00 sec; p < 0.0001) and temperatures (39.26°C versus 34.73°C; p = 0.043) were observed in the cortical group compared to the corticocancellous group. A remarkable variability of results characterized the corticocancellous blocks as compared to the blocks of pure cortical bone. Conclusion. Bone samples can influence heat generation during in vitro implant site preparation. When compared to cortical bone, corticocancellous samples present more variability in temperature values. Even controlling most experimental factors, the impact of bone samples still remains one of the main causes of temperature variability. PMID:27110567

  13. The variability of California summertime marine stratus: impacts on surface air temperatures

    USGS Publications Warehouse

    Iacobellis, Sam F.; Cayan, Daniel R.

    2013-01-01

    This study investigates the variability of clouds, primarily marine stratus clouds, and how they are associated with surface temperature anomalies over California, especially along the coastal margin. We focus on the summer months of June to September when marine stratus are the dominant cloud type. Data used include satellite cloud reflectivity (cloud albedo) measurements, hourly surface observations of cloud cover and air temperature at coastal airports, and observed values of daily surface temperature at stations throughout California and Nevada. Much of the anomalous variability of summer clouds is organized over regional patterns that affect considerable portions of the coast, often extend hundreds of kilometers to the west and southwest over the North Pacific, and are bounded to the east by coastal mountains. The occurrence of marine stratus is positively correlated with both the strength and height of the thermal inversion that caps the marine boundary layer, with inversion base height being a key factor in determining their inland penetration. Cloud cover is strongly associated with surface temperature variations. In general, increased presence of cloud (higher cloud albedo) produces cooler daytime temperatures and warmer nighttime temperatures. Summer daytime temperature fluctuations associated with cloud cover variations typically exceed 1°C. The inversion-cloud albedo-temperature associations that occur at daily timescales are also found at seasonal timescales.

  14. Interannual and interdecadal variability in United States surface-air temperatures, 1910-87

    USGS Publications Warehouse

    Dettinger, M.D.; Ghil, M.; Keppenne, C.L.

    1995-01-01

    Monthly mean surface-air temperatures at 870 sites in the contiguous United States were analyzed for interannual and interdecadal variability over the time interval 1910-87. The temperatures were analyzed spatially by empirical-orthogonal-function analysis and temporally by singularspectrum analysis (SSA). The dominant modes of spatio-temporal variability are trends and nonperiodic variations with time scales longer than 15 years, decadal-scale oscillations with periods of roughly 7 and 10 years, and interannual oscillations of 2.2 and 3.3 years. Together, these modes contribute about 18% of the slower-than-annual United States temperature variance. Two leading components roughly capture the mean hemispheric temperature trend and represent a long-term warming, largest in the southwest, accompanied by cooling of the domain's southeastern quadrant. The extremes of the 2.2-year interannual oscillation characterize temperature differences between the Northeastern and Southwestern States, whereas the 3.3-year cycle is present mostly in the Western States. The 7- to 10-year oscillations are much less regular and persistent than the interannual oscillations and characterize temperature differences between the western and interior sectors of the United States. These continental- or regional-scale temperature variations may be related to climatic variations with similar periodicities, either global or centered in other regions; such variations include quasi-biennial oscillations over the tropical Pacific or North Atlantic and quasi-triennial oscillations of North Pacific sea-surface temperatures.

  15. What do foraging wasps optimize in a variable environment, energy investment or body temperature?

    PubMed

    Kovac, Helmut; Stabentheiner, Anton; Brodschneider, Robert

    2015-11-01

    Vespine wasps (Vespula sp.) are endowed with a pronounced ability of endothermic heat production. To show how they balance energetics and thermoregulation under variable environmental conditions, we measured the body temperature and respiration of sucrose foragers (1.5 M, unlimited flow) under variable ambient temperature (T a = 20-35 °C) and solar radiation (20-570 W m(-2)). Results revealed a graduated balancing of metabolic efforts with thermoregulatory needs. The thoracic temperature in the shade depended on ambient temperature, increasing from ~37 to 39 °C. However, wasps used solar heat gain to regulate their thorax temperature at a rather high level at low T a (mean T thorax ~ 39 °C). Only at high T a they used solar heat to reduce their metabolic rate remarkably. A high body temperature accelerated the suction speed and shortened foraging time. As the costs of foraging strongly depended on duration, the efficiency could be significantly increased with a high body temperature. Heat gain from solar radiation enabled the wasps to enhance foraging efficiency at high ambient temperature (T a = 30 °C) by up to 63 %. The well-balanced change of economic strategies in response to environmental conditions minimized costs of foraging and optimized energetic efficiency. PMID:26286881

  16. Changes in Rice with Variable Temperature Parboling: Thermal and Spectroscopic Assessment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rapid visco analysis (RVA) and differential scannning calorimetry (DSC)provided overall assessments of the effects of variable temperature soaking at 30, 50, 70, and 90°C and steaming at 4, 8, and 12 min. Calculation of the relative parboiling index (RPI) and percent gelatinization provided good met...

  17. Variable-Temperature Cryostat For Radiation-Damage Testing Of Germanium Detectors

    NASA Technical Reports Server (NTRS)

    Floyd, Samuel R.; Puc, Bernard P.

    1992-01-01

    Variable-temperature cryostats developed to study radiation damage to, and annealing of, germanium gamma-ray detectors. Two styles: one accommodates large single detector and one accommodates two medium-sized detectors. New cryostats allow complete testing of large-volume germanium gamma-ray detectors without breaking cryostat vacuum and removing detectors for annealing.

  18. 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.

  19. Fingerprints of anthropogenic and natural variability in global-mean surface temperature

    SciTech Connect

    Wallace, J.M.; Zhang, Yuan

    1997-11-01

    This paper presents an analysis designed to detect greenhouse warming by distinguishing between temperature rises induced by increasing atmospheric concentrations of greenhouse gases and those induced by background variability that are present without changes in atmospheric composition. The strategy is based on the surface temperature field. At each observation time, the projection of the anomalous temperature field on the presumed anthropogenic fingerprint is removed in order to obtain a temperature deviation field; i.e., the temperature anomalies in the phase space orthogonal to the anthropogenic fingerprint, which are presumed to be entirely natural. The time series of the expansion coefficients of the fingerprint a(t) is then regressed on this temperature deviation field to identify the axis in the orthogonal phase space along which the variations are most strongly correlated, and an index n(t) of the temporal variations along that axis is generated. The index a(t) is then regressed upon n(t) and the resulting least squares fit is regarded as the component of a(t) that can be ascribed to natural causes. The analysis was performed for monthly global surface temperature anomaly fields for the period 1900-95. Results indicate that two well defined patterns of natural variability contribute to variations in global mean temperature: the synthetic cold ocean-warm land (COWL) pattern and the El Nino-Southern Oscillation (ENSO). In domains that include surface air temperature over Eurasia and North America, the COWL pattern tends to be dominant. The ENSO signature emerges as the pattern most strongly linearly correlated with global sea surface temperature and with tropospheric layer-averaged temperatures. 24 refs., 3 figs.

  20. Associations of multi-decadal sea-surface temperature variability with US drought

    USGS Publications Warehouse

    McCabe, G.J.; Betancourt, J.L.; Gray, S.T.; Palecki, M.A.; Hidalgo, H.G.

    2008-01-01

    Recent research suggests a link between drought occurrence in the conterminous United States (US) and sea surface temperature (SST) variability in both the tropical Pacific and North Atlantic Oceans on decadal to multidecadal (D2M) time scales. Results show that the Atlantic Multidecadal Oscillation (AMO) is the most consistent indicator of D2M drought variability in the conterminous US during the 20th century, but during the 19th century the tropical Pacific is a more consistent indicator of D2 M drought. The interaction between El Nin??o-Southern Oscillation (ENSO) and the AMO explain a large part of the D2M drought variability in the conterminous US. More modeling studies are needed to reveal possible mechanisms linking low-frequency ENSO variability and the AMO with drought in the conterminous US. ?? 2007 Elsevier Ltd and INQUA.

  1. Climate variability analysis of winter temperatures in the central Mediterranean since 1500 AD

    NASA Astrophysics Data System (ADS)

    Diodato, Nazzareno; Bellocchi, Gianni; Bertolin, Chiara; Camuffo, Dario

    2014-04-01

    This work presents the reconstruction of a time series of annual winter air temperatures across Central and Southern Italy for the period 1500-2010 that largely overlaps the Little Ice Age (LIA) period (1300-1850). A detailed analysis was undertaken on winter mean temperature data using both observations (1871-2010) and proxy-based reconstructions (1500-1870). Based on this homogeneized reconstructed series, a time-dependency in low-frequency time-pattern of temperatures (70- and 130-year cycles) was suggested although the temporal oscillation was not merely periodic. The LIA was characterized by marked climatic variability over this part of Southern Europe, with particular emphasis during the so-called "Maunder Minimum" (MM), between 1645 and 1715. The interannual variability of low temperatures, in particular, makes the MM an outstanding climatic period. There is some consistency that patterns of warming conditions observed in recent times also occurred in the past. Quasiperiodic cycles appear as a consequence of stochastic resonance emerging in long time scales but the variability inherent to the series of winter temperatures, although likely generated by processes internal to the climate system, is difficult to forecast because the system is chaotic and affected by unpredictable noise.

  2. 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.

  3. Performance analysis of eccentric annular fins with a variable base temperature

    SciTech Connect

    Kundu, B.; Das, P.K.

    1999-11-26

    The paper presents a numerical technique for the determination of the performance of eccentric annular fins with a variable base temperature. The differential equation for heat conduction in the fin has been written in a bipolar coordinate, which facilitates proper imposition of the boundary conditions. The control volume based finite difference method has been adopted to obtain the temperature distribution in the fin. Accuracy of the numerical result has been checked against that obtained from a semianalytical technique for the limiting condition of constant base temperature. Efficiencies of eccentric annular fins have been computed for different parametric variations. It has further been shown that for a nonuniform base temperature distribution, eccentric annular fins may dissipate more heat compared to a concentric fin of the same volume and there exists an optimum value of eccentricity that maximizes the rate of heat transfer. Therefore a saving in fin material may be achieved using eccentric annular fins if there exists a variation of base temperature.

  4. Connecting Atlantic temperature variability and biological cycling in two earth system models

    NASA Astrophysics Data System (ADS)

    Gnanadesikan, Anand; Dunne, John P.; Msadek, Rym

    2014-05-01

    Connections between the interdecadal variability in North Atlantic temperatures and biological cycling have been widely hypothesized. However, it is unclear whether such connections are due to small changes in basin-averaged temperatures indicated by the Atlantic Multidecadal Oscillation (AMO) Index, or whether both biological cycling and the AMO index are causally linked to changes in the Atlantic Meridional Overturning Circulation (AMOC). We examine interdecadal variability in the annual and month-by-month diatom biomass in two Earth System Models with the same formulations of atmospheric, land, sea ice and ocean biogeochemical dynamics but different formulations of ocean physics and thus different AMOC structures and variability. In the isopycnal-layered ESM2G, strong interdecadal changes in surface salinity associated with changes in AMOC produce spatially heterogeneous variability in convection, nutrient supply and thus diatom biomass. These changes also produce changes in ice cover, shortwave absorption and temperature and hence the AMO Index. Off West Greenland, these changes are consistent with observed changes in fisheries and support climate as a causal driver. In the level-coordinate ESM2M, nutrient supply is much higher and interdecadal changes in diatom biomass are much smaller in amplitude and not strongly linked to the AMO index.

  5. Sensitivity of Soil Respiration to Variability in Soil Moisture and Temperature in a Humid Tropical Forest

    PubMed Central

    Wood, Tana E.; Detto, Matteo; Silver, Whendee L.

    2013-01-01

    Precipitation and temperature are important drivers of soil respiration. The role of moisture and temperature are generally explored at seasonal or inter-annual timescales; however, significant variability also occurs on hourly to daily time-scales. We used small (1.54 m2), throughfall exclusion shelters to evaluate the role soil moisture and temperature as temporal controls on soil CO2 efflux from a humid tropical forest in Puerto Rico. We measured hourly soil CO2 efflux, temperature and moisture in control and exclusion plots (n = 6) for 6-months. The variance of each time series was analyzed using orthonormal wavelet transformation and Haar-wavelet coherence. We found strong negative coherence between soil moisture and soil respiration in control plots corresponding to a two-day periodicity. Across all plots, there was a significant parabolic relationship between soil moisture and soil CO2 efflux with peak soil respiration occurring at volumetric soil moisture of approximately 0.375 m3/m3. We additionally found a weak positive coherence between CO2 and temperature at longer time-scales and a significant positive relationship between soil temperature and CO2 efflux when the analysis was limited to the control plots. The coherence between CO2 and both temperature and soil moisture were reduced in exclusion plots. The reduced CO2 response to temperature in exclusion plots suggests that the positive effect of temperature on CO2 is constrained by soil moisture availability. PMID:24312508

  6. Stream temperature response to variable glacier coverage in coastal watersheds of northern southeast Alaska

    NASA Astrophysics Data System (ADS)

    Hood, E. W.; Fellman, J. B.; Nagorski, S. A.; Vermilyea, A.; Pyare, S.; Scott, D.

    2012-12-01

    Glaciers in southeast Alaska are experiencing high rates of ice thinning and retreat. These ongoing changes in glacier volume are altering the proportion of streamflow derived from glacial runoff, which can be an important control on the thermal regime of streams in the region. We measured stream temperature continuously during the 2011 summer runoff season (May through October) in nine watersheds of southeast Alaska that provide spawning habitat for Pacific salmon. Six of the nine watersheds have glacier coverage ranging from 2 to 63%. Our goal was to determine how air temperature and watershed land cover, particularly glacier coverage, influence stream temperature across the seasonal hydrograph. Multiple linear regression identified mean watershed elevation, which is tied to glacier extent, and watershed lake coverage (%) as the strongest landscape controls on mean monthly stream temperature, with the weakest (May) and strongest (July) models explaining 86% and 97% of the temperature variability, respectively. Mean weekly stream temperature was significantly related to mean weekly air temperature in seven of the nine streams; however, the relationships were weak to non-significant in the streams dominated by glacial runoff. Peak summer stream temperatures occurred much earlier in the glacial streams (typically around late May) and glaciers also had a cooling effect on monthly mean stream temperature during the summer (July through September) equivalent to a decrease of 1.1°C for each 10% increase in glacier coverage. Streams with >30% glacier coverage demonstrated decreasing stream temperatures with rising summer air temperatures, while those with <30% glacier coverage exhibited summertime warming. The maximum weekly average temperature (MWAT, an index of thermal suitability for salmon species) in the six glacial streams was substantially below the lower threshold for optimum salmonid growth. This finding suggests that, while glaciers are important for moderating summer stream temperatures, future reductions in glacier runoff may actually improve the thermal suitability of some streams in northern southeast Alaska for salmon.

  7. 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.

  8. Water Temperature Variability Along the West Coast of the Gulf of California

    NASA Astrophysics Data System (ADS)

    God¡nez, L.; Gutierrez de Velasco, G.; Halfar, J.; Valdez, J. E.; Borges, J. M.

    2003-12-01

    The seawater temperature variability along the west coast of the Gulf of California for the time period March 2002 to March 2003 is discussed. The observations used for the analysis correspond to hourly samples at 10, 15, 20, and 25 m depths from moorings deployed in 35 m total depth at four locations along the west gulf coast, from its mouth to Ballenas channel: Cabo Pulmo (23° 23' N, 109° 25 W), Isla Espíritu Santo (24° 33' N, 110° 24' W), Punta Chivato (27° 04' N, 111° 58' W), and Bahía de los Ángeles (28° 58' N, 113° 31' W). Mean sea water temperatures increase along the gulf from the temperate north region to the subtropical gulf entrance (17 to 26° C). Temperature variability shows periodicities ranging from the seasonal to the semi-diurnal frequencies with decreasing amplitudes as frequency increases. Temperature seasonal cycle changes along the Gulf coast. Its amplitude diminishes from north to south were maximum temperature values are reached about 30 days later. Maximum and minimum values in the cycle increase northward; in contrast to the southward decreasing amplitude. Frequencies higher than seasonal exhibit two distinct patterns: An active spring and summer period and a quiet fall and winter one. During spring and summer vertical temperature differences increase and variability is dominated by 2 to 5° C amplitude oscillations at diurnal, 5 to 7 day, and quarterly frequencies. Fall and winter exhibit an almost constant vertical temperature distribution with weak oscillations (<1° C amplitude) at the same frequencies.

  9. Interannual and interdecadal variability in 335 years of central England temperatures.

    PubMed

    Plaut, G; Ghil, M; Vautard, R

    1995-05-01

    Understanding the natural variability of climate is important for predicting its near-term evolution. Models of the oceans' thermohaline and wind-driven circulation show low-frequency oscillations. Long instrumental records can help validate the oscillatory behavior of these models. Singular spectrum analysis applied to the 335-year-long central England temperature (CET) record has identified climate oscillations with interannual (7- to 8-year) and interdecadal (15- and 25-year) periods, probably related to the North Atlantic's wind-driven and thermohaline circulation, respectively. Statistical prediction of oscillatory variability shows CETs decreasing toward the end of this decade and rising again into the middle of the next. PMID:17832386

  10. Projected intensification of subseasonal temperature variability and heat waves in the Great Plains

    NASA Astrophysics Data System (ADS)

    Teng, Haiyan; Branstator, Grant; Meehl, Gerald A.; Washington, Warren M.

    2016-03-01

    Compared to changes in the climatological mean temperature, we have less confidence in how much and by what mechanisms temperature variability may be affected by anthropogenic climate change. Here based on a 30-member climate change projection from an earth system model, we find that summertime subseasonal temperature variability in the U.S. Great Plains is enhanced by approximately 20% in 2070-2100 relative to 1980-2010. In particular, daily temperature departures from the new climatologies during future heat waves are on average 0.6°C warmer than are the corresponding departures under present-day conditions. Although in both periods heat waves in the Great Plains tend to be associated with planetary wave events, the amplification of future heat waves does not appear to be induced by changes in planetary wave variability in the midlatitudes. Instead, in this experiment the strengthening appears to be primarily caused by enhanced local land-atmosphere feedbacks resulting from a warmer/drier future climate.

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

    NASA Astrophysics Data System (ADS)

    Gritsch, Christine; Zechmeister-Boltenstern, Sophie

    2014-05-01

    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 60%) over all sites. We found that the relationship between CO2 emissions and temperature could be well described by the equation PIC (R2 ranges from 0.98 to 1) over all sites. In general CO2 emissions were strongly related with both variables temperature and moisture. However, temperature sensitivity of soil respiration was strongly declined under very dry and very wet conditions (5 and >80 % WFPS moisture content). Moisture sensitivity of CO2 emissions was positive related to temperature, although at low temperatures (5-10° C) moisture content had almost no effect on CO2 emissions. In summary our results indicate that the variability in soil temperature and moisture decisively controls soil CO2 emissions, while land use had only a minor impact and describe the effect and dependencies of temperature and moisture on the development of CO2 emissions.

  12. 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.

  13. Climate variability and relationships between top-of-atmosphere radiation and temperatures on Earth

    NASA Astrophysics Data System (ADS)

    Trenberth, Kevin E.; Zhang, Yongxin; Fasullo, John T.; Taguchi, Shoichi

    2015-05-01

    The monthly global and regional variability in Earth's radiation balance is examined using correlations and regressions between atmospheric temperatures and water vapor with top-of-atmosphere outgoing longwave (OLR), absorbed shortwave (ASR), and net radiation (RT = ASR - OLR). Anomalous global mean monthly variability in the net radiation is surprisingly large, often more than ±1 W m-2, and arises mainly from clouds and transient weather systems. Relationships are strongest and positive between OLR and temperatures, especially over land for tropospheric temperatures, except in the deep tropics where high sea surface temperatures are associated with deep convection, high cold cloud tops and thus less OLR but also less ASR. Tropospheric vertically averaged temperatures (surface = 150 hPa) are thus negatively correlated globally with net radiation (-0.57), implying 2.18 ± 0.10 W m-2 extra net radiation to space for 1°C increase in temperature. Water vapor is positively correlated with tropospheric temperatures and thus also negatively correlated with net radiation; however, when the temperature dependency of water vapor is statistically removed, a significant positive feedback between water vapor and net radiation is revealed globally with 0.87 W m-2 less OLR to space per millimeter of total column water vapor. The regression coefficient between global RT and tropospheric temperature becomes -2.98 W m-2 K-1 if water vapor effects are removed, slightly less than expected from blackbody radiation (-3.2 W m-2 K-1), suggesting a positive feedback from clouds and other processes. Robust regional structures provide additional physical insights. The observational record is too short, weather noise too great, and forcing too small to make reliable estimates of climate sensitivity.

  14. On the design and implementation of a novel impedance chamber based variable temperature regulator at liquid helium temperatures.

    PubMed

    Nagendran, R; Thirumurugan, N; Chinnasamy, N; Janawadkar, M P; Sundar, C S

    2010-04-01

    A novel variable temperature regulator (VTR) based on the use of a fine impedance capillary to control the flow rate of cold helium gas into the VTR chamber is described. The capillary has a diameter of just 200 microm and the flow rate of cold helium gas through the capillary can be effectively controlled to the desired value by heating the capillary to a preset temperature and by controlling the pressure in the VTR chamber to a preset pressure using automated control circuits. Excellent temperature stability (about +/-1 mK at 10 K and +/-2 mK at 100 K) has been demonstrated in this setup with uniform rates of heating or cooling by an optimal choice of parameters. Compared to the more conventional VTR designs based on the use of mechanical long stem valves in the liquid helium reservoir to control the flow rate of liquid helium into the VTR chamber, and the use of a needle valve at the top of the cryostat to control the exchange gas pressure in the thermal isolation chamber, the present design enables temperature stability at any user desired temperature to be attained with uniform rates of cooling/heating with minimum consumption of liquid helium. The VTR has been successfully incorporated in the high field superconducting quantum interference device magnetometer setup developed in-house. It can also be incorporated in any low temperature physical property measurement system in which the temperature has to be varied in a controlled manner from 4.2 to 300 K and vice versa with uniform rates of heating and cooling. PMID:20441373

  15. Implications of solar irradiance variability upon long-term changes in the Earth's atmospheric temperatures

    NASA Technical Reports Server (NTRS)

    Lee, Robert B., III

    1992-01-01

    From 1979 through 1987, it is believed that variability in the incoming solar energy played a significant role in changing the Earth's climate. Using high-precision spacecraft radiometric measurements, the incoming total solar irradiance (total amount of solar power per unit area) and the Earth's mean, global atmospheric temperatures were found to vary in phase with each other. The observed irradiance and temperature changes appeared to be correlated with the 11-year cycle of solar magnetic activity. During the period from 1979 through 1985, both the irradiance and temperature decreased. From 1985 to 1987, they increased. The irradiance changed approximately 0.1 percent, while the temperature varied as much as 0.6 C. During the 1979-1987 period, the temperatures were forecasted to rise linearly because of the anthropogenic build-up of carbon dioxide and the hypothesized 'global warming', 'greenhouse effect', scenarios. Contrary to these scenarios, the temperatures were found to vary in a periodic manner in phase with the solar irradiance changes. The observed correlations between irradiance and temperature variabilily suggest that the mean, global temperature of the Earth may decline between 1990 and 1997 as solar magnetic activity decreases.

  16. Noctilucent cloud formation and the effects of water vapor variability on temperatures in the middle atmosphere

    NASA Technical Reports Server (NTRS)

    Mckay, C. P.

    1985-01-01

    To investigate the occurrence of low temperatures and the formation of noctilucent clouds in the summer mesosphere, a one-dimensional time-dependent photochemical-thermal numerical model of the atmosphere between 50 and 120 km has been constructed. The model self-consistently solves the coupled photochemical and thermal equations as perturbation equations from a reference state assumed to be in equilibrium and is used to consider the effect of variability in water vapor in the lower mesosphere on the temperature in the region of noctilucent cloud formation. It is found that change in water vapor from an equilibrium value of 5 ppm at 50 km to a value of 10 ppm, a variation consistent with observations, can produce a roughly 15 K drop in temperature at 82 km. It is suggested that this process may produce weeks of cold temperatures and influence noctilucent cloud formation.

  17. Interannual variability of the atmospheric CO2 growth rate: relative contribution from precipitation and temperature

    NASA Astrophysics Data System (ADS)

    Wang, J.; Zeng, N.; Wang, M. R.

    2015-12-01

    The interannual variability (IAV) in atmospheric CO2 growth rate (CGR) is closely connected with the El Niño-Southern Oscillation. However, sensitivities of CGR to temperature and precipitation remain largely uncertain. This paper analyzed the relationship between Mauna Loa CGR and tropical land climatic elements. We find that Mauna Loa CGR lags precipitation by 4 months with a correlation coefficient of -0.63, leads temperature by 1 month (0.77), and correlates with soil moisture (-0.65) with zero lag. Additionally, precipitation and temperature are highly correlated (-0.66), with precipitation leading by 4-5 months. Regression analysis shows that sensitivities of Mauna Loa CGR to temperature and precipitation are 2.92 ± 0.20 Pg C yr-1 K-1 and -0.46 ± 0.07 Pg C yr-1 100 mm-1, respectively. Unlike some recent suggestions, these empirical relationships favor neither temperature nor precipitation as the dominant factor of CGR IAV. We further analyzed seven terrestrial carbon cycle models, from the TRENDY project, to study the processes underlying CGR IAV. All models capture well the IAV of tropical land-atmosphere carbon flux (CFTA). Sensitivities of the ensemble mean CFTA to temperature and precipitation are 3.18 ± 0.11 Pg C yr-1 K-1 and -0.67 ± 0.04 Pg C yr-1 100 mm-1, close to Mauna Loa CGR. Importantly, the models consistently show the variability in net primary productivity (NPP) dominates CGR, rather than soil respiration. Because NPP is largely driven by precipitation, this suggests a key role of precipitation in CGR IAV despite the higher CGR correlation with temperature. Understanding the relative contribution of CO2 sensitivity to precipitation and temperature has important implications for future carbon-climate feedback using such "emergent constraint".

  18. Interannual variability of the atmospheric CO2 growth rate: roles of precipitation and temperature

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Zeng, Ning; Wang, Meirong

    2016-04-01

    The interannual variability (IAV) in atmospheric CO2 growth rate (CGR) is closely connected with the El Niño-Southern Oscillation. However, sensitivities of CGR to temperature and precipitation remain largely uncertain. This paper analyzed the relationship between Mauna Loa CGR and tropical land climatic elements. We find that Mauna Loa CGR lags precipitation by 4 months with a correlation coefficient of -0.63, leads temperature by 1 month (0.77), and correlates with soil moisture (-0.65) with zero lag. Additionally, precipitation and temperature are highly correlated (-0.66), with precipitation leading by 4-5 months. Regression analysis shows that sensitivities of Mauna Loa CGR to temperature and precipitation are 2.92 ± 0.20 PgC yr-1 K-1 and -0.46 ± 0.07 PgC yr-1 100 mm-1, respectively. Unlike some recent suggestions, these empirical relationships favor neither temperature nor precipitation as the dominant factor of CGR IAV. We further analyzed seven terrestrial carbon cycle models, from the TRENDY project, to study the processes underlying CGR IAV. All models capture well the IAV of tropical land-atmosphere carbon flux (CFTA). Sensitivities of the ensemble mean CFTA to temperature and precipitation are 3.18 ± 0.11 PgC yr-1 K-1 and -0.67 ± 0.04 PgC yr-1 100 mm-1, close to Mauna Loa CGR. Importantly, the models consistently show the variability in net primary productivity (NPP) dominates CGR, rather than heterotrophic respiration. Because previous studies have proved that NPP is largely driven by precipitation in tropics, it suggests a key role of precipitation in CGR IAV despite the higher CGR correlation with temperature. Understanding the relative contribution of CO2 sensitivity to precipitation and temperature has important implications for future carbon-climate feedback using such ''emergent constraint''.

  19. Evaluating the first-order effect of intraannual temperature variability on urban air pollution

    NASA Astrophysics Data System (ADS)

    Aw, Jeremy; Kleeman, Michael J.

    2003-06-01

    The direct effect of intraannual temperature variability on ozone and PM2.5 concentrations at the urban scale was simulated using a high-resolution air quality model that tracks the temperature-dependant formation of secondary organic and inorganic aerosol components. Calculations show that the concentration of ozone and non-volatile secondary particulate matter will generally increase at higher temperatures due to increased gas-phase reaction rates. The concentration of semi-volatile reaction products also will increase at higher temperatures, but the amount of this material that partitions to the particle-phase may decrease as equilibrium vapor pressures rise. Calculations performed for Southern California on September 25, 1996 predict that intraannual temperature variability may cause peak ozone and PM2.5 concentrations to fluctuate by up to 16% and 25% respectively. 24-hour average PM2.5 concentrations will decrease with increasing temperatures for inland portions of the South Coast air basin during most of the day. Slight increases in 24-hour average PM2.5 concentrations were predicted for coastal regions. The majority of the predicted shift in PM2.5 concentrations was related to increased production rates for nitric acid and condensable organic compounds balanced against increased volatilization of these products. Semi-volatile particulate ammonium nitrate concentrations are most sensitive to volatilization losses at hotter temperatures and when the ratio of gas-phase ammonia to nitric acid concentrations is approximately unity. Background sulfate particles and particles released from non-catalyst equipped gasoline-powered engines, diesel engines, and food cooking were shifted to smaller sizes as ammonium nitrate volatilized at hotter temperatures.

  20. Small-scale variability of alpine snow packs from fiber-optic distributed temperature

    NASA Astrophysics Data System (ADS)

    Huwald, H.; Williams, S.; Higgins, C. W.; Nolin, A. W.; Drake, S. A.; Selker, J. S.; Parlange, M. B.

    2012-04-01

    Variations in small-scale surface roughness, snow density and in the snowpack microstructure influence the surface and internal snow temperature, being key quantities for various heat flux components of the surface energy balance. Detailed knowledge on the spatial distribution and temporal evolution of snow temperature is crucial to quantify spatial variability in the subsurface and surface heat fluxes of the snow pack. We present measurements of small-scale temperature variations in alpine snow packs using fiber-optic distributed temperature sensing (DTS) together with traditional sensors at spatial resolutions much smaller than most common distributed snow cover models to shed light on subgrid-scale physics. Fiber-optic cables of several 100m were installed in a fence-like configuration in in the Swiss Alps to obtain 2D information on subgrid-scale snow variability. The setup allowed for computation of subsurface heat fluxes at 1m spatial resolution along the measurement transect based on the Fourier heat equation using snow temperature and snow depth data, and an effective thermal conductivity of the snow derived from density measurements.

  1. The use of variable temperature and magic-angle sample spinning in studies of fulvic acids

    USGS Publications Warehouse

    Earl, W.L.; Wershaw, R. L.; Thorn, K.A.

    1987-01-01

    Intensity distortions and poor signal to noise in the cross-polarization magic-angle sample spinning NMR of fulvic acids were investigated and attributed to molecular mobility in these ostensibly "solid" materials. We have shown that inefficiencies in cross polarization can be overcome by lowering the sample temperature to about -60??C. These difficulties can be generalized to many other synthetic and natural products. The use of variable temperature and cross-polarization intensity as a function of contact time can yield valuable qualitative information which can aid in the characterization of many materials. ?? 1987.

  2. 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.

  3. Atmospheric response to the North Pacific enabled by daily sea surface temperature variability

    NASA Astrophysics Data System (ADS)

    Zhou, Guidi; Latif, Mojib; Greatbatch, Richard J.; Park, Wonsun

    2015-09-01

    Ocean-atmosphere interactions play a key role in climate variability on a wide range of timescales from seasonal to decadal and longer. The extratropical oceans are thought to exert noticeable feedbacks on the atmosphere especially on decadal and longer timescales, yet the large-scale atmospheric response to anomalous extratropical sea surface temperature (SST) is still under debate. Here we show, by means of dedicated high-resolution atmospheric model experiments, that sufficient daily variability in the extratropical background SST needs to be resolved to force a statistically significant large-scale atmospheric response to decadal North Pacific SST anomalies associated with the Pacific Decadal Oscillation, which is consistent with observations. The large-scale response is mediated by atmospheric eddies. This implies that daily extratropical SST fluctuations must be simulated by the ocean components and resolved by the atmospheric components of global climate models to enable realistic simulation of decadal North Pacific sector climate variability.

  4. 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.

  5. 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.

  6. Black Sea temperature response to glacial millennial-scale climate variability

    NASA Astrophysics Data System (ADS)

    Wegwerth, Antje; Ganopolski, Andrey; Ménot, Guillemette; Kaiser, Jérôme; Dellwig, Olaf; Bard, Edouard; Lamy, Frank; Arz, Helge W.

    2015-10-01

    The Eurasian inland propagation of temperature anomalies during glacial millennial-scale climate variability is poorly understood, but this knowledge is crucial to understanding hemisphere-wide atmospheric teleconnection patterns and climate mechanisms. Based on biomarkers and geochemical paleothermometers, a pronounced continental temperature variability between 64,000 and 20,000 years ago, coinciding with the Greenland Dansgaard-Oeschger cycles, was determined in a well-dated sediment record from the formerly enclosed Black Sea. Cooling during Heinrich events was not stronger than during other stadials in the Black Sea. This is corroborated by modeling results showing that regular Dansgaard-Oeschger cycles penetrated deeper into the Eurasian continent than Heinrich events. The pattern of coastal ice-rafted detritus suggests a strong dependence on the climate background state, with significantly milder winters during periods of reduced Eurasian ice sheets and an intensified meridional atmospheric circulation.

  7. 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.

  8. Speed and shape of dust acoustic solitary waves with variable dust charge and two temperature ions

    NASA Astrophysics Data System (ADS)

    Das, Brindaban; Chatterjee, Prasanta

    2006-06-01

    Dust acoustic solitary waves are investigated on the nonlinear, unmagnetized homogeneous dust ion electron plasma with variable dust charge and two temperature ions. The Sagdeev's pseudopotential is determined in terms of ud, the dust ion speed. It is found that there exists a critical value of ud, beyond which the solitary waves cease to exist. This critical value of ud depends on other plasma parameters also.

  9. Variable conductance heat pipe technology for precise temperature control of the NASA/DDLT transmitter

    NASA Technical Reports Server (NTRS)

    Vanevenhoven, D. E.; Antoniak, D.

    1989-01-01

    The application of variable conductance heat pipe technology for achieving precise temperature control to + or - 0.1 C for a space-based laser diode transmitter is described. Heat pipe theory of operation and test data are presented along with a discussion of its applicability for NASA's Direct Detection Laser Transceiver (DDLT) program. This design for the DDLT transmitter features a reduction in space radiator size and up to 42 percent reduction in prime power requirements.

  10. 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

  11. Wood density provides new opportunities for reconstructing past temperature variability from southeastern Australian trees

    NASA Astrophysics Data System (ADS)

    O'Donnell, Alison J.; Allen, Kathryn J.; Evans, Robert M.; Cook, Edward R.; Trouet, Valerie; Baker, Patrick J.

    2016-06-01

    Tree-ring based climate reconstructions have been critical for understanding past variability and recent trends in climate worldwide, but they are scarce in Australia. This is particularly the case for temperature: only one tree-ring width based temperature reconstruction - based on Huon Pine trees from Mt Read, Tasmania - exists for Australia. Here, we investigate whether additional tree-ring parameters derived from Athrotaxis cupressoides trees growing in the same region have potential to provide robust proxy records of past temperature variability. We measured wood properties, including tree-ring width (TRW), mean density, mean cell wall thickness (CWT), and tracheid radial diameter (TRD) of annual growth rings in Athrotaxis cupressoides, a long-lived, high-elevation conifer in central Tasmania, Australia. Mean density and CWT were strongly and negatively correlated with summer temperatures. In contrast, the summer temperature signal in TRW was weakly positive. The strongest climate signal in any of the tree-ring parameters was maximum temperature in January (mid-summer; JanTmax) and we chose this as the target climate variable for reconstruction. The model that explained most of the variance in JanTmax was based on TRW and mean density as predictors. TRW and mean density provided complementary proxies with mean density showing greater high-frequency (inter-annual to multi-year) variability and TRW showing more low-frequency (decadal to centennial-scale) variability. The final reconstruction model is robust, explaining 55% of the variance in JanTmax, and was used to reconstruct JanTmax for the last five centuries (1530-2010 C.E.). The reconstruction suggests that the most recent 60 years have been warmer than average in the context of the last ca. 500 years. This unusually warm period is likely linked to a coincident increase in the intensity of the subtropical ridge and dominance of the positive phase of the Southern Annular Mode in summer, which weaken the influence of the band of prevailing westerly winds and storms on Tasmanian climate. Our findings indicate that wood properties, such as mean density, are likely to provide significant contributions toward the development of robust climate reconstructions in the Southern Hemisphere and thus toward an improved understanding of past climate in Australasia.

  12. Intraseasonal temperature variability in the upper troposphere and lower stratosphere from the GPS radio occultation measurements

    NASA Astrophysics Data System (ADS)

    Tian, Baijun; Ao, Chi O.; Waliser, Duane E.; Fetzer, Eric J.; Mannucci, Anthony J.; Teixeira, Joao

    2012-08-01

    In this study, we examine the detailed spatiotemporal patterns and vertical structure of the intraseasonal temperature variability in the upper troposphere and lower stratosphere (UTLS) associated with the Madden-Julian Oscillation (MJO) using the temperature profiles from the recent Global Positioning System radio occultation (GPS RO) measurements including the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) mission. The MJO-related temperature anomalies in the UTLS are smaller near the equator (<0.6 K) than over the subtropics and extratropics (>1.2 K). Near the equator, the temperature anomalies exhibit an eastward tilt with height from the upper troposphere (UT) to the lower stratosphere (LS) and their magnitudes and signs are determined by the strength of convective anomalies and vertical pressure level. The subtropical temperature anomalies have similar magnitudes and patterns at a given location between the UT (250 hPa to 150 hPa) and the LS (150 hPa to 50 hPa) except for opposite signs that change around 150 hPa. The subtropical warm (cold) anomalies in the UT and cold (warm) anomalies in the LS are typically collocated with the subtropical positive (negative) tropopause height anomalies/cyclones (anticyclones) and flank or lie to the west of equatorial enhanced (suppressed) convection. We also compare the intraseasonal temperature variability in the UTLS related to the MJO between the GPS RO and Atmospheric Infrared Sounder (AIRS) measurements to highlight the new features of the GPS RO temperature anomalies and to evaluate the quality of the AIRS temperature in the UTLS considering the GPS RO temperature in the UTLS as the benchmark. Both AIRS and GPS RO have a very consistent vertical structure in the subtropical UTLS with a high correlation coefficient 0.92 and similar magnitudes. Both AIRS and GPS RO also show a generally consistent vertical structure of the intraseasonal temperature anomalies in the equatorial UTLS. However, GPS RO reveals many detailed fine-scale vertical structures of the equatorial temperature anomalies between 150 and 50 hPa that are not well captured by AIRS. Furthermore, the equatorial temperature anomalies are about 40% underestimated in AIRS in comparison to GPS RO, over the equatorial Indian and western Pacific Oceans for 250 hPa and over all longitudes for 100 hPa. The low sampling within the optically thick clouds and low vertical resolution near the tropopause may both contribute to these deficiencies of AIRS.

  13. 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.

  14. An analysis of surface air temperature trends and variability along the Andes

    NASA Astrophysics Data System (ADS)

    Franquist, Eric S.

    Climate change is difficult to study in mountainous regions such as the Andes since steep changes in elevation cannot always be resolved by climate models. However, it is important to examine temperature trends in this region as rises in surface air temperature are leading to the melting of tropical glaciers. Local communities rely on the glacier-fed streamflow to get their water for drinking, irrigation, and livestock. Moreover, communities also rely on the tourism of hikers who come to the region to view the glaciers. As the temperatures increase, these glaciers are no longer in equilibrium with their current climate and are receding rapidly and decreasing the streamflow. This thesis examines surface air temperature from 858 weather stations across Ecuador, Peru, and Chile in order to analyze changes in trends and variability. Three time periods were studied: 1961--1990, 1971--2000, and 1981--2010. The greatest warming occurred during the period of 1971--2000 with 92% of the stations experiencing positive trends with a mean of 0.24°C/decade. There was a clear shift toward cooler temperatures at all latitudes and below elevations of 500 m during the most recent time period studied (1981--2010). Station temperatures were more strongly correlated with the El Nino Southern Oscillation (ENSO), than the Pacific Decadal Oscillation (PDO), and the Southern Annular Mode (SAM). A principal component analysis confirmed ENSO as the main contributor of variability with the most influence in the lower latitudes. There were clear multidecadal changes in correlation strength for the PDO. The PDO contributed the most to the increases in station temperature trends during the 1961--1990 period, consistent with the PDO shift to the positive phase in the middle of this period. There were many strong positive trends at individual stations during the 1971--2000 period; however, these trends could not fully be attributed to ENSO, PDO, or SAM, indicating anthropogenic effects of greenhouse gas emissions as the most likely cause.

  15. Decadal variability in Gulf of Mexico sea surface temperatures since 1734 CE

    NASA Astrophysics Data System (ADS)

    DeLong, K. L.; Maupin, C. R.; Flannery, J. A.; Quinn, T. M.; lin, K.; Shen, C.

    2012-12-01

    The Gulf of Mexico is a major source of moisture to North America and is a source region for the Gulf Stream, which transports ocean heat northward. Sea surface temperature (SST) variations on centennial to millennial time scales have been documented for this region using paleoceanographic proxies; however, records capable of resolving decadal to subannual variability are lacking. Here we present 274 years of monthly-resolved SST variations derived from records of strontium-to-calcium ratios (Sr/Ca) extracted from four Siderastrea siderea cores recovered from coral colonies within the Dry Tortugas National Park (24°42‧N, 82°48‧W) in the Gulf of Mexico. We find no significant difference in mean Sr/Ca among these cores and significant correlation between cores (r ≥ 0.90, p ≤ 0.05 for monthly). The cross-dated chronology, determined by counting annual bands and correlating Sr/Ca variations, agrees with four 230Th dates within ±2σ analytical precision. Calibration and verification of our multi-core coral Sr/Ca record with local temperature records reveals high agreement (Sr/Ca = -0.042 SST + 10.074, R2 = 0.96; σregression = 0.70°C, 1σ), similar to those reported for single cores from this location. We find winter SSTs tend to be more variable than summer SSTs (0.99 and 0.81°C, 1σ; respectively) with periodic intervals of 10 to 15 years with cooler summer temperatures. The average reconstructed SST during the Little Ice Age (LIA; 1734-1880 CE) is colder (-0.82°C) than that during the late twentieth century (1971-2000 CE). The amplitude of decadal-scale variability (1 to 2.5°C) in the LIA is larger compared to similar scale variability in the twentieth century. The secular trend and decadal-scale variability in our reconstruction is broadly similar to an ~ decadally-resolved (~12 years/sample) Mg/Ca record from planktic foraminifer in the northern Gulf of Mexico (Richey et al., 2007), thus further confirming the reconstructed patterns of temperature variability in the Gulf of Mexico during the LIA.

  16. 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.

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

    NASA Astrophysics Data System (ADS)

    Pages 2k-Pmip3 Group

    2015-12-01

    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 a collection of state-of-the-art model simulations driven by realistic external forcings are jointly analysed. The first aim is to estimate the consistency between model results and reconstructions for each continental-scale region over the 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-latitude 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 palaeoclimate records than in the Northern Hemisphere.

  18. Enhanced future variability during India's rainy season

    NASA Astrophysics Data System (ADS)

    Menon, Arathy; Levermann, Anders; Schewe, Jacob

    2013-04-01

    The Indian summer monsoon shapes the livelihood of a large share of the world's population. About 80% of annual precipitation over India occurs during the monsoon season from June through September. Next to its seasonal mean rainfall the day-to-day variability is crucial for the risk of flooding, national water supply and agricultural productivity. Here we show that the latest ensemble of climate model simulations, prepared for the IPCC's AR-5, consistently projects significant increases in day-to-day rainfall variability under unmitigated climate change. While all models show an increase in day-to-day variability, some models are more realistic in capturing the observed seasonal mean rainfall over India than others. While no model's monsoon rainfall exceeds the observed value by more than two standard deviations, half of the models simulate a significantly weaker monsoon than observed. The relative increase in day-to-day variability by the year 2100 ranges from 15% to 48% under the strongest scenario (RCP-8.5), in the ten models which capture seasonal mean rainfall closest to observations. The variability increase per degree of global warming is independent of the scenario in most models, and is 8% +/- 4% per K on average. This consistent projection across 20 comprehensive climate models provides confidence in the results and suggests the necessity of profound adaptation measures in the case of unmitigated climate change.

  19. 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.

  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. Spatial scales of temperature and salinity variability estimated from Argo observations

    NASA Astrophysics Data System (ADS)

    Ninove, F.; Le Traon, P.-Y.; Remy, E.; Guinehut, S.

    2016-01-01

    Argo observations from 2005 to 2013 are used to characterize spatial scales of temperature and salinity variations from the surface down to 1300 m. Simulations are first performed to analyze the sensitivity of results to Argo sampling; they show that several years of Argo observations are required to estimate spatial scales of ocean variability over 20° × 20° boxes. Spatial scales are then computed over several large-scale areas. Zonal and meridional spatial scales (Lx and Ly which are zero crossing of covariance functions) vary as expected with latitudes. Scales are of about 100 km at high latitudes and more of 700 km in the Indian and Pacific equatorial-tropical regions. Zonal and meridional scales are similar except in tropical-equatorial regions where zonal scales are much larger (by a factor of 2 to 3) than meridional scales. Spatial scales are the largest close to the surface and have a general tendency for temperature to increase in deeper layers. There are significant differences between temperature and salinity scales, in particular, in the deep ocean. Results are consistent with previous studies based on sparse in situ observations or satellite altimetry. They provide, however, for the first time a global description of temperature and salinity scales of variability and a characterization of their variations according to depths.

  2. Variability in Postarrest Targeted Temperature Management Practice: Implications of the 2015 Guidelines.

    PubMed

    Leary, Marion; Blewer, Audrey L; Delfin, Gail; Abella, Benjamin S

    2015-12-01

    In 2002 postarrest care was significantly altered when multiple randomized controlled trials found that therapeutic hypothermia at a goal temperature of 32-34°C significantly improved survival and neurologic outcomes. In 2013, targeted temperature management (TTM) was reexamined via a randomized controlled trial between 33°C and 36°C in post-cardiac arrest patients and found similar outcomes in both cohorts. Before the release of the 2015 American Heart Association (AHA) Guidelines, our group found that across hospitals in the United States, and even within the same institution, TTM protocol variability existed. After the 2013 TTM trial, it was anticipated that the 2015 Guidelines would clarify which target temperature should be used during postarrest care. The AHA released their updates for post-cardiac arrest TTM recently and, based on the literature available, have recommended the use of TTM at a goal temperature between 32°C and 36°C. Whether this variability has an effect on TTM implementation or patient outcomes is unknown. PMID:26642933

  3. Demonstration of a Variable Phase Turbine Power System for Low Temperature Geothermal Resources

    SciTech Connect

    Hays, Lance G

    2014-07-07

    A variable phase turbine assembly will be designed and manufactured having a turbine, operable with transcritical, two-phase or vapor flow, and a generator – on the same shaft supported by process lubricated bearings. The assembly will be hermetically sealed and the generator cooled by the refrigerant. A compact plate-fin heat exchanger or tube and shell heat exchanger will be used to transfer heat from the geothermal fluid to the refrigerant. The demonstration turbine will be operated separately with two-phase flow and with vapor flow to demonstrate performance and applicability to the entire range of low temperature geothermal resources. The vapor leaving the turbine is condensed in a plate-fin refrigerant condenser. The heat exchanger, variable phase turbine assembly and condenser are all mounted on single skids to enable factory assembly and checkout and minimize installation costs. The system will be demonstrated using low temperature (237F) well flow from an existing large geothermal field. The net power generated, 1 megawatt, will be fed into the existing power system at the demonstration site. The system will demonstrate reliable generation of inexpensive power from low temperature resources. The system will be designed for mass manufacturing and factory assembly and should cost less than $1,200/kWe installed, when manufactured in large quantities. The estimated cost of power for 300F resources is predicted to be less than 5 cents/kWh. This should enable a substantial increase in power generated from low temperature geothermal resources.

  4. Deglacial Subsurface Temperature Change in the Tropical North Atlantic Linked to Atlantic Meridional Overturning Circulation Variability

    NASA Astrophysics Data System (ADS)

    Schmidt, M. W.; Hertzberg, J. E.; Them, T. R.; Parker, A. O.; Chang, P.

    2011-12-01

    Coupled ocean-atmosphere modeling experiments conducted under both the present and Last Glacial Maximum (LGM) conditions indicate that Atlantic meridional overturning circulation (AMOC) variability is tightly coupled to abrupt tropical North Atlantic (TNA) climate change through both atmospheric and oceanic processes (Zhang, 2007; Chang et al., 2008; Chiang et al., 2008; Otto-Bliesner and Brady, 2009). While a slowdown of AMOC in these experiments results in an atmospheric-induced surface cooling in the entire TNA, the subsurface experiences an even larger warming due to rapid reorganizations of ocean circulation patterns (Wan et al., 2009). To test the hypothesis that subsurface temperature change in the TNA is coupled to AMOC variability across abrupt climate events over the last deglacial, we reconstruct Mg/Ca-temperature and δ18O records from both surface (Globigerinoides ruber, upper mixed layer) and sub-thermocline dwelling (Globorotalia truncatulinoides, 350-500 m depth) planktonic foraminifera, as well as from the benthic species Cibicidoides pachyderma in the southern Caribbean Sea sediment core VM12-107 (11.33 °N, 66.63 °W; 1079 m; 18 cm/kyr sedimentation rate). Reconstructed sea surface temperatures (SSTs) indicate a gradual warming in the TNA starting at ~19 kyr BP with small cold reversals of ~1.5 °C during Heinrich Event 1 (H1) and the Younger Dryas (YD). In contrast, LGM subsurface temperatures were as much as 2.5 °C warmer than Late Holocene values and H1 and the YD are marked by the warmest subsurface temperatures characterized by abrupt temperature increases as large as 4-5 °C. In addition, benthic Mg/Ca ratios during the YD and H1 increase by 50% relative to Holocene intervals, suggesting significant warming extending to 1079 m water depth across these events. Comparison of our subsurface temperature records with the Bermuda Rise 231Pa/230Th proxy record of AMOC variability (McManus et al., 2004) indicates a strong correlation between periods of reduced AMOC and subsurface warming in the southern Caribbean Sea. To confirm the subsurface warming is caused by basin-scale changes in intermediate-depth circulation rather than by local hydrographic dynamics, we will also reconstruct an intermediate-depth temperature record from inside the Cariaco Basin using G. truncatulinoides from ODP site 1002C. Because the Cariaco Basin sill depth was less than 100 m across the deglacial, intermediate-depth warming associated with AMOC variability should not affect intermediate-depth temperatures inside the basin. Our results suggest that western TNA subsurface temperature change is a sensitive indicator of AMOC strength with the potential to reconstruct past AMOC variability.

  5. Memory effects, two color percolation, and the temperature dependence of Mott variable-range hopping

    NASA Astrophysics Data System (ADS)

    Agam, Oded; Aleiner, Igor L.

    2014-06-01

    There are three basic processes that determine hopping transport: (a) hopping between normally empty sites (i.e., having exponentially small occupation numbers at equilibrium), (b) hopping between normally occupied sites, and (c) transitions between normally occupied and unoccupied sites. In conventional theories all these processes are considered Markovian and the correlations of occupation numbers of different sites are believed to be small (i.e., not exponential in temperature). We show that, contrary to this belief, memory effects suppress the processes of type (c) and manifest themselves in a subleading exponential temperature dependence of the variable-range hopping conductivity. This temperature dependence originates from the property that sites of type (a) and (b) form two independent resistor networks that are weakly coupled to each other by processes of type (c). This leads to a two-color percolation problem which we solve in the critical region.

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

    SciTech Connect

    Hobara, Rei; Nagamura, Naoka; Hasegawa, Shuji; Matsuda, Iwao; Yamamoto, Yuko; Miyatake, Yutaka; Nagamura, Toshihiko

    2007-05-15

    The authors have developed an ultrahigh vacuum (UHV) variable-temperature four-tip scanning tunneling microscope (STM), operating from room temperature down to 7 K, combined with a scanning electron microscope (SEM). Four STM tips are mechanically and electrically independent and capable of positioning in arbitrary configurations in nanometer precision. An integrated controller system for both of the multitip STM and SEM with a single computer has also been developed, which enables the four tips to operate either for STM imaging independently and for four-point probe (4PP) conductivity measurements cooperatively. Atomic-resolution STM images of graphite were obtained simultaneously by the four tips. Conductivity measurements by 4PP method were also performed at various temperatures with the four tips in square arrangement with direct contact to the sample surface.

  7. Water transport in cement-in-polymer dispersions at variable temperature studied by magnetic resonance imaging

    SciTech Connect

    Olaru, A.M. Bluemich, B.; Adams, A.

    2013-02-15

    The hydration of recently developed cement-in-polymer dispersions (c/p) containing 30% and 40% poly (vinyl acetate) [PVAc] and 30% poly(vinyl alcohol) [PVA] was monitored on-line at various temperatures using {sup 1}H Single Point Imaging (SPI). The physical changes undergone by the materials as well as the complex manner in which the absorption process takes place and the evolution of the spin density were characterized and were found to be strongly dependent on the nature and amount of polymer and on the temperature. Based on the results obtained we propose a simple mathematical model which can be used to characterize the behaviour of the c/p dispersions exposed to hydration at variable temperature.

  8. Variable range hopping conduction in n-CdSe samples at very low temperature

    NASA Astrophysics Data System (ADS)

    Errai, M.; El Kaaouachi, A.; El Idrissi, H.

    2015-12-01

    We reanalyzed experimental data already published in Friedman J R, Zhang Y, Dai P, et al. Phys Rev B, 1996, 53(15): 9528. Variable range hopping (VRH) conduction in the insulating three-dimensional n-CdSe samples has been studied over the entire temperature range from 0.03 to 1 K. In the absence of a magnetic field, the low temperature conductivity σ of the three samples (A, B and C) obeys the Mott VRH conduction with an appropriate temperature dependence in the prefactor (σ = σ0 exp[–(T0/T)]p with p ≈ 0.25). This behavior can be explained by a VRH model where the transport occurs by hopping between localized states in the vicinity of the Fermi level, EF, without creation of the Coulomb gap (CG). On the contrary, no Efros-Shklovskii VRH is observed, suggesting that the density is constant in the vicinity of the EF.

  9. 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.

  10. Evidence for A Weakening Relationship between Interannual Temperature Variability and Northern Vegetation Activity

    NASA Astrophysics Data System (ADS)

    Piao, S.; Nan, H.; Huntingford, C.; Ciais, P.; Friedlingstein, P.; Sitch, S.; Peng, S.; Ahlström, A.; Canadell, J.; Cong, N.; Levis, S.; Levy, P. E.; Liu, L.; Lomas, M.; Mao, J.; Myneni, R.; Peylin, P. P.; Poulter, B.; Shi, X.; Yin, G.; Viovy, N.; Wang, T.; Wang, X.; Zaehle, S.; Zeng, N.; Zeng, Z.; Chen, A.

    2014-12-01

    Satellite derived Normalized Difference Vegetation Index (NDVI), a proxy of vegetation productivity, is known to be correlated with temperature in northern ecosystems. Here we show that above 30 oN, the strength of the relationship between the interannual variability of growing season NDVI and temperature (partial correlation coefficient RNDVI-GT) has declined substantially between 1982 and 2011, although with a heterogeneous spatial pattern. This decrease of RNDVI-GT is mainly observed in temperate and arctic ecosystems, and this phenomenon also partly reproduced by process-based ecosystem model results. In the northern temperate zone, the decrease of RNDVI-GT coincides with an increase of drought. In the arctic it may be related to a nonlinear response of photosynthesis to temperature, increase of hot extreme days, and shrub expansion over grass-dominated tundra. Our results caution the use of results from interannual time scales to constrain decadal response of plants to ongoing warming.

  11. 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.

  12. 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

    2016-05-01

    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.

  13. 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.

  14. 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 δ13C 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.

  15. Ambient temperature, air pollution, and heart rate variability in an aging population.

    PubMed

    Ren, Cizao; O'Neill, Marie S; Park, Sung Kyun; Sparrow, David; Vokonas, Pantel; Schwartz, Joel

    2011-05-01

    Studies show that ambient temperature and air pollution are associated with cardiovascular disease and that they may interact to affect cardiovascular events. However, few epidemiologic studies have examined mechanisms through which ambient temperature may influence cardiovascular function. The authors examined whether temperature was associated with heart rate variability (HRV) in a Boston, Massachusetts, study population and whether such associations were modified by ambient air pollution concentrations. The population was a cohort of 694 older men examined between 2000 and 2008. The authors fitted a mixed model to examine associations between temperature and air pollution and their interactions with repeated HRV measurements, adjusting for covariates selected a priori on the basis of their previous studies. Results showed that higher ambient temperature was associated with decreases in HRV measures (standard deviation of normal-to-normal intervals, low-frequency power, and high-frequency power) during the warm season but not during the cold season. These warm-season associations were significantly greater when ambient ozone levels were higher (>22.3 ppb) but did not differ according to levels of ambient fine (≤2.5 μm) particulate matter. The authors conclude that temperature and ozone, exposures to both of which are expected to increase with climate change, might act together to worsen cardiovascular health and/or precipitate cardiovascular events via autonomic nervous system dysfunction. PMID:21385834

  16. 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.

  17. Scales of temporal and spatial variability of midlatitude land surface temperature

    NASA Astrophysics Data System (ADS)

    Vinnikov, Konstantin Y.; Yu, Yunyue; Goldberg, Mitchell D.; Chen, Ming; Tarpley, Dan

    2011-01-01

    Scales of temporal and spatial variability of clear-sky land surface temperature (LST) in middle latitudes are empirically evaluated using data from satellite and land surface observations. We consider separately the time-dependent expected value, its spatial variations, weather-related temporal and spatial anomalies, and errors of LST observation. Seasonal and diurnal cycles in the time-dependent expected value of LST are found to be the main components of temporal variations of clear-sky LST. The scale of spatial variability in the expected value of LST is found to be much smaller than the scale of spatial variability of the weather-related signal. The scale of temporal autocorrelation of weather-related LST variations is found to be in a good agreement with our earlier preliminary estimate and equal to 3 d, which corresponds to the time scale of weather system variations. This weather-related signal in clear-sky LST is statistically the same as in surface air temperature (SAT) observations at regular meteorological stations. The scale of spatial autocorrelation of weather-related LST variations exceeds 1000 km, which is the spatial scale of synoptic weather systems. These estimates provide us with a basis for better understanding and interpretation of LST observations from past, current, and future geostationary satellites and polar orbiters.

  18. From Snow Depth Distribution to Small-Scale Variability of Soil Temperatures

    NASA Astrophysics Data System (ADS)

    Gisnås, Kjersti; Westermann, Sebastian; Etzelmüller, Bernd; Schuler, Thomas V.

    2013-04-01

    Permafrost is a temperature phenomenon on the local scale. Soil temperatures are not only influenced by atmospheric conditions varying on scales of kilometers, but are also determined by the land cover and soil properties, which display large variability on the meter-scale in many permafrost areas. In mountain areas the seasonal snow cover is crucial for the ground thermal regime, and the redistribution of snow by wind can create a pattern of different snow depths, which results in spatially variable permafrost temperatures. Existing permafrost models (CryoGRID1.0 and CryoGRID2.0) are implemented at 1x1km spatial resolution for Norway, and have proven to capture the regional distribution of permafrost. One of the principal uncertainties of these models is the effect of sub-grid variability in snow cover, and downscaling approaches for snow are therefore required to get a satisfactorily representation of the ground thermal regime. An extensive dataset including ground temperatures of 7 boreholes and data of 5 stations measuring snow depth and air/ground surface temperature is available from Juvflye, a high-mountain site in central southern Norway (1800-1900m a.s.l.). The area has a rough topography and a seasonal snow cover dominated by heavy wind redistribution. A Ground Penetration Radar (GPR) survey of snow depth was conducted in March 2012, covering an 8km2 area including the 7 boreholes. This GPR-survey will be repeated in 2013. The measured snow depths form the basis for probability density functions (PDFs) of snow cover within each 1x1km grid cell for this area. A 1-D numerical model including both a soil thermal model and snow pack scheme are calibrated for all 7 boreholes. Several model runs are performed for different snow depths, intended to cover the range of observed values. We present the effects of different snow depths on the thermal regime of the underlying permafrost, based on this model attempt. Furthermore, we outline a probabilistic approach for including sub-grid variability of snow depth in grid-based permafrost models.

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

    NASA Astrophysics Data System (ADS)

    Astor, Y. M.; Lorenzoni, L.; Thunell, R.; Varela, R.; Muller-Karger, F.; Troccoli, L.; Taylor, G. T.; Scranton, M. I.; Tappa, E.; Rueda, D.

    2013-09-01

    We examined the variability of sea surface carbon dioxide fugacity (fCO2sea) and its relation to temperature at the Cariaco Basin ocean time-series location (10°30'N, 64°40'W) for the period from 1996 through 2008. Periods of warm (positive) and cold (negative) anomalies at the station were related to variability in coastal upwelling intensity. A positive temporal trend in monthly-deseasonalized sea surface temperatures (SST) was observed, leading to an overall increase of 1.13 °C over 13 years. Surface fCO2sea displayed significant short-term variation (month to month) with a range of 330-445 μatm. In addition to a large seasonal range (58±17 μatm), deseasonalized fCO2sea data showed an interannual positive trend of 1.77±0.43 μatm yr-1. In the Cariaco Basin, positive and negative anomalies of temperature and fCO2sea are in phase. An increase/decrease of 1 °C coincides with an increase/decrease of 16-20 μatm of fCO2sea. Deseasonalized fCO2sea normalized to 26.05 °C, the mean Cariaco SST, shows a lower rate of increase (0.51±0.49 μatm yr-1). Based on these observations, 72% of the increase in fCO2sea in Cariaco Basin between 1996 and 2008 can be attributed to an increasing temperature trend of surface waters, making this the primary factor controlling fugacity at this location. During this period, a decrease in upwelling intensity was also observed. The phytoplankton community changed from large diatom-dominated blooms during upwelling in the late 1990's to blooms dominated by smaller cells in the first decade of the 21st century. The average net sea-air CO2 flux over the study period is 2.0±2.6 mol C m-2 yr-1 employing the Wanninkhof parameterization, and 2.1±2.5 mol C m-2 yr-1 based on Nightingale's model. To further understand the connection between the changes observed in the Cariaco Basin, the relationships between interannual variability in the temperature anomaly with three modes of climate variability (AMO, NAO and ENSO) were examined. The correlations between SSTA and two of these climate modes (AMO and ENSO) only show very weak relationships, although they were significant.

  20. Impact of the dominant large-scale teleconnections on winter temperature variability over East Asia

    NASA Astrophysics Data System (ADS)

    Lim, Young-Kwon; Kim, Hae-Dong

    2013-07-01

    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 Niño-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 50°N is prevailed by AO and EA/WR impacts, temperature in the midlatitudes (30°N-50°N), 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 30°N 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.

  1. Streams in the urban heat island: spatial and temporal variability in temperature

    USGS Publications Warehouse

    Somers, Kayleigh A.; Bernhardt, Emily S.; Grace, James B.; Hassett, Brooke A.; Sudduth, Elizabeth B.; Wang, Siyi; Urban, Dean L.

    2013-01-01

    Streams draining urban heat islands tend to be hotter than rural and forested streams at baseflow because of warmer urban air and ground temperatures, paved surfaces, and decreased riparian canopy. Urban infrastructure efficiently routes runoff over hot impervious surfaces and through storm drains directly into streams and can lead to rapid, dramatic increases in temperature. Thermal regimes affect habitat quality and biogeochemical processes, and changes can be lethal if temperatures exceed upper tolerance limits of aquatic fauna. In summer 2009, we collected continuous (10-min interval) temperature data in 60 streams spanning a range of development intensity in the Piedmont of North Carolina, USA. The 5 most urbanized streams averaged 21.1°C at baseflow, compared to 19.5°C in the 5 most forested streams. Temperatures in urban streams rose as much as 4°C during a small regional storm, whereas the same storm led to extremely small to no changes in temperature in forested streams. Over a kilometer of stream length, baseflow temperature varied by as much as 10°C in an urban stream and as little as 2°C in a forested stream. We used structural equation modeling to explore how reach- and catchment-scale attributes interact to explain maximum temperatures and magnitudes of storm-flow temperature surges. The best predictive model of baseflow temperatures (R2  =  0.461) included moderately strong pathways directly (extent of development and road density) and indirectly, as mediated by reach-scale factors (canopy closure and stream width), from catchment-scale factors. The strongest influence on storm-flow temperature surges appeared to be % development in the catchment. Reach-scale factors, such as the extent of riparian forest and stream width, had little mitigating influence (R2  =  0.448). Stream temperature is an essential, but overlooked, aspect of the urban stream syndrome and is affected by reach-scale habitat variables, catchment-scale urbanization, and stream thermal regimes.

  2. 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.

  3. Interannual and interdecadal variability in 335 years of central England temperatures

    SciTech Connect

    Plaut, G.; Ghil, M.; Vautard, R.

    1995-05-05

    Understanding the natural variability of climate is important for predicting its near-term evolution. Models of the oceans` thermohaline and wind-driven circulation show low-frequency oscillations. Long instrumental records can help validate the oscillatory behavior of these models. Singular spectrum analysis applied to the 335-year-long central England temperature (CET) record has identified climate oscillations with interannual (7- to 8-year) and interdecadal (15- and 25-year) periods, probably related to the North Atlantic`s wind-driven and thermohaline circulation, respectively. Statistical prediction of oscillatory variability shows CETs decreasing toward the end of this decade and rising again into the middle of the next. 42 refs., 4 figs.

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

    SciTech Connect

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

    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.

  5. The effect of light radiation and temperature variability on the invasion of marine fouling species

    NASA Astrophysics Data System (ADS)

    Kim, T.; Micheli, F.

    2009-12-01

    Climate change can alter the community structure as species which have adapted to the changed climate can compete better with other species. It can also influence the recruitment and invasion success of marine introduced species. Climate change involves not only global warming but also global dimming. However, it was not tested which of warming or dimming factors more significantly influence the invasion of marine species. To test this, we manipulated both temperature variability and light radiation by deploying different shading devices (black, white, transparent, and no treatment) for recruitment tiles in the warmer region where the species invasion rate is high. We compared the species frequency and coverage between shaded and non-shaded treatments. Interestingly, under opaque white plates where light radiation is lower than under transparent plates but the temperature is higher than under black plates, had the highest frequency and coverage of invasive fouling species. The recruitment tiles under black plates got second higher invasion of exotic species. We also deployed recruitment tiles in 14 different sites to determine if temperature influences the success of invasive species. The coverage of invasive species over native species increased significantly with increasing temperature. The results suggest that both low radiation and higher temperature facilitates the success of species invasion in the intertidal region.

  6. Ozone Depletion at Mid-Latitudes: Coupling of Volcanic Aerosols and Temperature Variability to Anthropogenic Chlorine

    NASA Technical Reports Server (NTRS)

    Solomon, S.; Portmann, R. W.; Garcia, R. R.; Randel, W.; Wu, F.; Nagatani, R.; Gleason, J.; Thomason, L.; Poole, L. R.; McCormick, M. P.

    1998-01-01

    Satellite observations of total ozone at 40-60 deg N are presented from a variety of instruments over the time period 1979-1997. These reveal record low values in 1992-3 (after Pinatubo) followed by partial but incomplete recovery. The largest post-Pinatubo reductions and longer-term trends occur in spring, providing a critical test for chemical theories of ozone depletion. The observations are shown to be consistent with current understanding of the chemistry of ozone depletion when changes in reactive chlorine and stratospheric aerosol abundances are considered along with estimates of wave-driven fluctuations in stratospheric temperatures derived from global temperature analyses. Temperature fluctuations are shown to make significant contributions to model calculated northern mid-latitude ozone depletion due to heterogeneous chlorine activation on liquid sulfate aerosols at temperatures near 200-210 K (depending upon water vapor pressure), particularly after major volcanic eruptions. Future mid-latitude ozone recovery will hence depend not only on chlorine recovery but also on temperature trends and/or variability, volcanic activity, and any trends in stratospheric sulfate aerosol.

  7. Past Temperature Variability Inferred from Tree-Ring Records for the Past Millennium

    NASA Astrophysics Data System (ADS)

    D'Arrigo, R.; Wilson, R.

    2012-12-01

    Tree rings are an important proxy for inferring past temperature variability as they are precisely dated to the year and, especially for higher latitude and alpine treeline regions of the world, can be very sensitive to past changes in temperature on interannual to much lower frequency (centennial) time scales. Temperatures can be reconstructed from both ring widths and maximum latewood density time series, which are complementary parameters with different strengths and weaknesses. Hemispheric-scale temperature reconstructions based on such data are highly useful records for inferring temperature changes over the past millennium, as well as the past sensitivity of the Earth's climate system. One hundred years of tree-ring science have identified no real evidence that adverse climatic events can cause such severely cold conditions that no rings might form at any of the trees at a given site, resulting in misdating of the final chronology. Rather, based on both tree-ring observations and modeling analyses, there is clear evidence of precise dating and laying down of rings in at least some trees at each site even under extremely adverse cold conditions.

  8. Investigating planetary wave and seasonal variability in mesospheric temperature at mid- and low-latitudes

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Taylor, M.; Gardner, C.; Liu, A.

    The Utah State University Mesospheric Temperature Mapper MTM is a high performance CCD imaging system developed as part of the US CEDAR program This imager sequentially measures the nocturnal OH 6 2 band intensity and rotational temperature peak altitude sim 87km and the O 2 0 1 Atmospheric band intensity and temperature peak altitude sim 94km with a precision of 1-2 K in 3 minutes The MTM is capable of autonomous operation and since 1998 long-term seasonal measurements were obtained from the mid-latitude Starfire Optical Range SOR facility 35 r N NM duration 14 months Subsequently the imager was relocated to the low-latitude 21 r N at USAF AEOS facility at Maui Hawaii and long-term measurements were obtained as part of the Maui-MALT program 2001-2005 Over 500 nights of quality data have been obtained to date These measurements are constitute an important dataset for seasonal studies and were obtained in coordination with the University of Illinois Na wind temperature lidar which operated on a campaign basis from both of these facilities Together these two datasets have been used to investigate the occurrence and signatures of planetary waves and to compare seasonal variability in mesospheric temperature at mid- and low-latitudes

  9. Using skin temperature variability to quantify surface and subsurface estuarine processes

    NASA Astrophysics Data System (ADS)

    Brumer, S. E.; Zappa, C. J.; Anderson, S. P.; Dugan, J. P.

    2012-12-01

    IR imagery is a unique tool to study nearshore processes. It not only provides a measure for surface skin temperature, but also permits the determination of surface currents. Variations in the skin temperature arise from disruption and renewal of the thermal boundary layer (TBL) as a result of wind forcing at the air-water interface, or due to turbulent eddies generated from below. The TBL plays a critical role in nearshore processes, in particular air-water heat and gas exchanges. It is essential to characterize the spatio-temporal scales of the disruption of the TBL and the extent to which it is renewed, as well as to understand how environmental factors relate to skin temperature variability. Furthermore, it is necessary to evaluate the ability not only to derive surface currents, but also to infer subsurface properties and processes from IR images. Estuarine and inlet environments such as the Hudson River are more complex, with multitude of additional processes at play, compared to the open ocean. For instance, the atmospheric boundary layer is complicated by the fact that that air is moving over both land and water, flow is fetch limited and there is orographic steering of winds. In addition, the subsurface turbulence is enhanced due to the bottom boundary layer. Here, high resolution IR imagery was collected from a ship stationed roughly 12 miles upstream of the New York Harbor in November 2010. On a nearby piling, several in situ instruments were mounted both above and below water, measuring environmental parameters such as wind speed, heat fluxes, air and water temperature, humidity as well as subsurface currents, turbulence, temperature and salinity. An IR imager installed on the cliff overlooking the river provided a complete view of the experiment area, with both the ship and the steel piling in its field of view. This study aims not only to characterize the skin temperature variability, but also to assess the validity of the various models for surface renewal found in the literature. Correlations between the measured skin temperature and environmental conditions (above and below surface) will give an insight on the physical processes governing surface temperatures. With the goal of determining subsurface flow characteristics from the surface flow statistics, three methods to derive surface velocity vectors are used. The results from the different techniques will be inter-compared and verified with in situ data in the aim to find the strengths and limitations of the various techniques. Further, relations between derived surface flow and measured subsurface flow will be investigated and the derived velocities will allow inferring turbulence statistics, in particular TKE dissipations rates.

  10. 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.

  11. Effects of Variable Temperature on Mossbauer Data Acquisition: Laboratory-based and MER A Results

    NASA Technical Reports Server (NTRS)

    Rothstein, Y.; Sklute, E. C.; Dyar, M. D.; Schaefer, M. W.

    2005-01-01

    Mossbauer spectrometers on the Spirit and Opportunity rovers have played a valuable role in identifying mineralogy at both the Gusev and Meridiani landing sites. Key to the application of Mossbauer results is the issue of how accurately the peak positions, on which the mineral identifications are based, can be determined. Remote Mossbauer spectroscopy has by necessity some unusual experimental constraints that may influence the confidence with which peak positions can be fit. We present here an analysis of the effects of variable temperature and short duration run times on spectral resolution.

  12. Solid-state variable-temperature NMR study of the phase separation of polybutadiene polyurethane zwitterionomers

    NASA Astrophysics Data System (ADS)

    Yang, G.; Chen, Q.; Wang, Y.; Yang, C.; Wu, X.

    1994-07-01

    Polybutadiene polyurethane (PBDPU) zwitterionomers based on 4,4'-diphenylmethane diisocyanate (MDI), methyl-diethanolamine (MDEA), and hydroxy terminated polybutadiene are studied with variable-temperature (VT) wide-line 1H NMR. Spin—spin relaxation times ( T2) and spin—lattice relaxation times ( T1) are measured. It is found that phase separation of PBDPU does not change significantly upon ionization. The initial incorporation of ionization groups destroys the crystallinity of the hard segment while further ionization enhances physical crosslinks in the hard phase. The results are compared with a previous VT NMR study on polyether polyurethane zwitterionomers based on MDI, MDEA and 1000 Da molecular weight polytetramethylene oxide.

  13. Complex interactions between climate change and toxicants: evidence that temperature variability increases sensitivity to cadmium.

    PubMed

    Kimberly, David A; Salice, Christopher J

    2014-07-01

    The Intergovernmental Panel on Climate Change projects that global climate change will have significant impacts on environmental conditions including potential effects on sensitivity of organisms to environmental contaminants. The objective of this study was to test the climate-induced toxicant sensitivity (CITS) hypothesis in which acclimation to altered climate parameters increases toxicant sensitivity. Adult Physa pomilia snails were acclimated to a near optimal 22 °C or a high-normal 28 °C for 28 days. After 28 days, snails from each temperature group were challenged with either low (150 μg/L) or high (300 μg/L) cadmium at each temperature (28 or 22 °C). In contrast to the CITS hypothesis, we found that acclimation temperature did not have a strong influence on cadmium sensitivity except at the high cadmium test concentration where snails acclimated to 28 °C were more cadmium tolerant. However, snails that experienced a switch in temperature for the cadmium challenge, regardless of the switch direction, were the most sensitive to cadmium. Within the snails that were switched between temperatures, snails acclimated at 28 °C and then exposed to high cadmium at 22 °C exhibited significantly greater mortality than those snails acclimated to 22 °C and then exposed to cadmium at 28 °C. Our results point to the importance of temperature variability in increasing toxicant sensitivity but also suggest a potentially complex cost of temperature acclimation. Broadly, the type of temporal stressor exposures we simulated may reduce overall plasticity in responses to stress ultimately rendering populations more vulnerable to adverse effects. PMID:24623389

  14. Photodissociation Spectroscopy of Ca^+-H_2O in the Temperature-Variable Ion Trap

    NASA Astrophysics Data System (ADS)

    Ishikawa, Haruki; Eguchi, Toru; Nakano, Takumi; Fujihara, Akimasa; Fuke, Kiyokazu

    2011-06-01

    In the last two decades, developments of infrared spectroscopy and theoretical calculations on gas-phase molecular clusters have revealed detailed solvation structures of various systems, especially of hydrogen-bonded systems. One of the remained problems in studies on microscopic solvation or hydration is a temperature dependence of solvation structures. Lisy and coworkers succeeded in interpreting the hydration structures of alkali metal ions by taking temperature- or entropic effect. They utilized Ar vaporization to cool down the temperature of clusters. Another method for controlling temperature of cluster ions is a buffer gas cooling in an ion trap. In the present study, we have measured photodissociation spectra of Ca^+-H_2O in our temperature-variable ion trap In the present study, we examined the temperature of the Ca^+-H_2O in the trap by simulating the rotational profile of the 0-0 band of the ^2B_1 - ^2A_1 transition. The observed rotational profile is similar to that reported by Duncan and coworkers. By changing the trap period from 10 ms to 40 ms, it was confirmed that the trap period of 10 ms is sufficient to get temperature equilibrium in our experimental condition. Details of the experimental results will be presented in the paper. D. J. Miller, J. M. Lisy J. Am. Chem. Soc. 130, 15393 (2008). A. Fujihara, et al. J. Phys. Chem. A 112, 1457 (2008) A. Fujihara, et al. J. Phys. Chem. A 113, 8169 (2009). C. T. Scurlock, S. H. Pullins, J. E. Reddic, M. A. Duncan J. Chem. Phys. 104, 4591 (1996).

  15. Summer temperature variability across four urban neighborhoods in Knoxville, Tennessee, USA

    NASA Astrophysics Data System (ADS)

    Ellis, Kelsey N.; Hathaway, Jon M.; Mason, Lisa Reyes; Howe, David A.; Epps, Thomas H.; Brown, Vincent M.

    2015-10-01

    The urban heat island (UHI) is a well-documented effect of urbanization on local climate, identified by higher temperatures compared to surrounding areas, especially at night and during the warm season. The details of a UHI are city-specific, and microclimates may even exist within a given city. Thus, investigating the spatiotemporal variability of a city's UHI is an ongoing and critical research need. We deploy ten weather stations across Knoxville, Tennessee, to analyze the city's UHI and its differential impacts across urban neighborhoods: two each in four neighborhoods, one in more dense tree cover and one in less dense tree cover, and one each in downtown Knoxville and Ijams Nature Center that serve as control locations. Three months of temperature data (beginning 2 July 2014) are analyzed using paired-sample t tests and a three-way analysis of variance. Major findings include the following: (1) Within a given neighborhood, tree cover helps negate daytime heat (resulting in up to 1.19 ∘C lower maximum temperature), but does not have as large of an influence on minimum temperature; (2) largest temperature differences between neighborhoods occur during the day (0.38-1.16 ∘C difference), but larger differences between neighborhoods and the downtown control occur at night (1.04-1.88 ∘C difference); (3) presiding weather (i.e., air mass type) has a significant, consistent impact on the temperature in a given city, and lacks the differential impacts found at a larger-scale in previous studies; (4) distance from city center does not impact temperature as much as land use factors. This is a preliminary step towards informing local planning with a scientific understanding of how mitigation strategies may help minimize the UHI and reduce the effects of extreme weather on public health and well-being.

  16. Periodic Analysis Between Solar Variability and the Earth's Temperature From Centuries to Ten Thousand Years

    NASA Astrophysics Data System (ADS)

    Zhao, X.; Feng, X. S.

    2014-12-01

    The global warming is one of the hottest topics for both scientists and the public at present. Strong evidences have shown that the global warming is related to the man-made increasing greenhouse gas levels. Besides the artificial factors, natural forces also contribute to the Earth's climate change. Among them, solar activity is an important ingredient of the natural driving forces of the Earth's climate. In this study, two data sets are adopted to investigate the periodicities of both solar activity and the variation of the Earth temperature as well as their correlations based on the wavelet analysis and cross correlation method. The first one is a directly measured data set covering centuries, while the second one is the reconstructed data during the past 11,000 years. The obtained results demonstrate that solar activity and the Earth's temperature have significant resonance cycles, and the Earth's temperature has periodic variations similar to those of solar activity. For centuries, these common periodicities include the 22-year cycle and the 50-year cycle. While for 11,000 years, they are the 200-year, 500-year, 1000-year, and 2000-year cycles. Correlation analysis reveals that the correlations between solar variability and the Earth's temperature are statistically significant. The correlation coefficient (C.C.) between the 11-year running averaged Total Solar Irradiance (TSI) and the ocean temperature is 0.88 during the past 133 years of global warming. While for 11,000 years, the C.C. between the 500-year running averages of sunspot number (SSN) and the Earth temperature (r=0.51, p=1%) is stronger than that between the temperature and the atmospheric CO2 concentration (r=0.35, p=10%). All these support that solar activity should have non-ignorable effects on the Earth's climate change, especially before the modern industrial time.

  17. Annual and seasonal variability of precipitation and temperatures in Slovenia from 1961 to 2011

    NASA Astrophysics Data System (ADS)

    Tošić, Ivana; Zorn, Matija; Ortar, Jaka; Unkašević, Miroslava; Gavrilov, Milivoj B.; Marković, Slobodan B.

    2016-02-01

    Spatial and temporal variability of annual and seasonal (summer and winter) precipitation sums and mean temperatures observed at forty-six stations in Slovenia from 1961 to 2011 were analysed. Principal component analysis (PCA) and a varimax rotation with Kaiser normalization were used to determine the dominant precipitation and temperature patterns in Slovenia. Time series data from the PCA (the principal components, PCs) were used to look for the existence of linear trends and periodicity in the precipitation and temperature data using the Mann-Kendall test and spectral analysis. The relationships between the PCs and circulation patterns, such as the North Atlantic Oscillation (NAO), the East Atlantic (EA) pattern, and the East Atlantic/West Russia (EA/WR) pattern, were also examined. The first four PCs of precipitation (temperature) contributed from 78.7% in summer to 94.5% in winter (98.4% in winter to 98.5% in summer) of the total variance, and their loadings indicated that the most (least) intensive signal was observed over mountainous northwest Slovenia. A statistically significant decrease of PC1 in annual precipitation and increase in mean annual and both seasonal temperatures was found. Significant relationships existed between annual and winter precipitation in Slovenia and the NAO, and temperature and the East Atlantic pattern from 1961 to 2011. Applying the spectral analysis, periods of 2.4 years in summer precipitation and 2.8 years in winter precipitation series, and 2.1 years in annual temperature (significant at the 5% level of significance) were found in Slovenia.

  18. Contrasting spatial patterns in the diurnal and semidiurnal temperature variability in the Santa Barbara Channel, California

    NASA Astrophysics Data System (ADS)

    Aristizábal, María. F.; Fewings, Melanie R.; Washburn, Libe

    2016-01-01

    The Santa Barbara Channel, California, experiences large temperature fluctuations during summer that have been associated with the input of nutrients to the euphotic zone. We studied the temperature fluctuations in the diurnal and semidiurnal bands, which account for as much as 65% of the total variance. We analyzed data from 25 moorings along the mainland and the Northern Channel Islands deployed at depths 8-18 m during 1999-2012. In the diurnal band, the temperature fluctuations vary almost simultaneously within two distinct regions, with a lag of 5 h between the regions: the mainland east of Point Conception and the west part of the Channel exposed to the large-scale winds. The two regions of in-phase temperature variability are in agreement with a previously published division of zones according to the wind characteristics. The portion of the diurnal temperature variance that is wind driven does not propagate along the coastline, but rather is directly forced by the wind. The semidiurnal temperature oscillations are more substantial in the Northern Channel Islands. These findings are consistent with a numerical study that predicted that the steep slopes of the Santa Cruz Basin, located south of the Channel Islands, are a source of semidiurnal internal tides. We conclude that the contrast between the spatial patterns of the diurnal and semidiurnal temperature oscillations on scales of tens of kilometers reflects the spatial distribution of the main forcing in each band, namely the diurnal wind and the locally generated semidiurnal internal tide. The spatial patterns of the diurnal and semidiurnal oscillations reflect the forcing in each band.

  19. 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.

  20. Thermodynamic modeling and performance analysis of the variable-temperature heat reservoir absorption heat pump cycle

    NASA Astrophysics Data System (ADS)

    Qin, Xiaoyong; Chen, Lingen; Ge, Yanlin; Sun, Fengrui

    2015-10-01

    For practical absorption heat pump (AHP) plants, not all external heat reservoir heat capacities are infinite. External heat reservoir heat capacity should be an effect factor in modeling and performance analysis of AHP cycles. A variable-temperature heat reservoir AHP cycle is modeled, in which internal working substance is working in four temperature levels and all irreversibility factors are considered. The irreversibility includes heat transfer irreversibility, internal dissipation irreversibility and heat leakage irreversibility. The general equations among coefficient of performance (COP), heating load and some key characteristic parameters are obtained. The general and optimal characteristics are obtained by using numerical calculations. Besides, the influences of heat capacities of heat reservoirs, internal dissipation irreversibility, and heat leakage irreversibility on cycle performance are analyzed. The conclusions can offer some guidelines for design and operation of AHP plants.

  1. Variable-Temperature Tip-Enhanced Raman Spectroscopy of Single-Molecule Fluctuations and Dynamics.

    PubMed

    Park, Kyoung-Duck; Muller, Eric A; Kravtsov, Vasily; Sass, Paul M; Dreyer, Jens; Atkin, Joanna M; Raschke, Markus B

    2016-01-13

    Structure, dynamics, and coupling involving single-molecules determine function in catalytic, electronic or biological systems. While vibrational spectroscopy provides insight into molecular structure, rapid fluctuations blur the molecular trajectory even in single-molecule spectroscopy, analogous to spatial averaging in measuring large ensembles. To gain insight into intramolecular coupling, substrate coupling, and dynamic processes, we use tip-enhanced Raman spectroscopy (TERS) at variable and cryogenic temperatures, to slow and control the motion of a single molecule. We resolve intrinsic line widths of individual normal modes, allowing detailed and quantitative investigation of the vibrational modes. From temperature dependent line narrowing and splitting, we quantify ultrafast vibrational dephasing, intramolecular coupling, and conformational heterogeneity. Through statistical correlation analysis of fluctuations of individual modes, we observe rotational motion and spectral fluctuations of the molecule. This work demonstrates single-molecule vibrational spectroscopy beyond chemical identification, opening the possibility for a complete picture of molecular motion ranging from femtoseconds to minutes. PMID:26679007

  2. 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.

  3. Variable-temperature measurements of the dielectric relaxation in carbon black loaded epoxy composites

    NASA Astrophysics Data System (ADS)

    Brosseau, C.; Achour, M. E.

    2009-06-01

    Technologically, an understanding of the temperature influence on the transport properties is essential to the study of many random conductor-insulator composites, while fundamentally it is related to a variety of questions in statistical physics, dielectrics, and materials science, to name a few. Variable-temperature measurements of the frequency dependent complex effective permittivity were performed on amine-cured epoxy resins loaded with carbon black (CB). Two series of prepercolative samples differing from the kind of CB particles (Raven 2000 and Raven 5000) mixed in an amine-cured epoxy matrix (diglycidylic ether of bisphenol F) were studied. In this effort to contribute to our understanding of the role of frequency (100 Hz-15 MHz) and temperature (from ambient temperature up to 90 °C) on the complex effective permittivity which describes the linear response of the system to an electromagnetic wave, we investigate these composites with CB loadings below the percolation threshold. Two features are observed. First, our observations cannot be understood in the typical framework of a simple Debye-like dipolar process. In this analysis, we argue that the appearance of the broad temperature and frequency dependent maximum loss can be understood within the heuristic framework proposed by Jonscher which applies to disordered heterogeneous systems. This theoretical framework is consistent with several aspects of the experiments, notably the power-law decays of the real and imaginary parts of the effective permittivity characterized by two fractional exponents m and n. These exponents are both positive and smaller than unity. We further quantified their different temperature variations: while m is strongly decreasing with increasing temperature, n takes a value close to 1. Second, the observed maximum loss frequency found for each CB volume fraction shifts to higher frequencies with increasing temperature and exhibits a non-Arrhenius temperature dependence well represented by a Vogel-Tammam-Fulcher (VTF) fit. Well below the percolation threshold, the associated activation energy and ordering temperature of the VTF fit are not significantly sensitive upon the CB concentration. Such results are compared to previous related work.

  4. Impact of Air Temperature and SST Variability on Cholera Incidence in Southeastern Africa, 1971-2006

    NASA Astrophysics Data System (ADS)

    Paz, Shlomit

    2010-05-01

    The most important climatic parameter related to cholera outbreaks is the temperature, especially of the water bodies and the aquatic environment. This factor governs the survival and growth of V. cholerae, since it has a direct influence on its abundance in the environment, or alternatively, through its indirect influence on other aquatic organisms to which the pathogen is found to attach. Thus, the potential for cholera outbreaks may rise, parallel to the increase in ocean surface temperature. Indeed, recent studies indicate that global warming might create a favorable environment for V. cholerae and increase its incidence in vulnerable areas. Africa is vulnerable to climate variability. According to the recent IPCC report on Africa, the air temperature has indicated a significant warming trend since the 1960s. In recent years, most of the research into disease vectors in Africa related to climate variability has focused on malaria. The IPCC indicated that the need exists to examine the vulnerabilities and impacts of climatic factors on cholera in Africa. In light of this, the study uses a Poisson Regression Model to analyze the possible association between the cholera rates in southeastern Africa and the annual variability of air temperature and sea surface temperature (SST) at regional and hemispheric scales, for the period 1971-2006. Data description is as follows: Number of cholera cases per year in Uganda, Kenya, Rwanda, Burundi, Tanzania, Malawi, Zambia and Mozambique. Source: WHO Global Health Atlas - cholera. Seasonal and annual temperature time series: Regional scale: a) Air temperature for southeastern Africa (30° E-36° E, 5° S-17° S), source: NOAA NCEP-NCAR; b) Sea surface temperature, for the western Indian Ocean (0-20° S, 40° E-45° E), source: NOAA, Kaplan SST dataset. Hemispheric scale (for the whole Southern Hemisphere): a) Air temperature anomaly; b) Sea surface temperature anomaly. Source: CRU, University of East Anglia. The following Poisson regression model is suggested: log{E(CHOLt)} = b0+b1×Xt+b2×Xt-1 where: CHOLt = the number of new cases of cholera in year t Xt / Xt-1 = the climate covariate measured in year t/t-1. (b0,b1) = the coefficients. A first order autocorrelation, AR1 = cor(Yt, Yt-1) is taken into account in the estimation using Generalized Estimating Equations. b1 and b2 quantify the association of CHOL and X, i.e. if Xt or Xt-1 increase by one unit, the mean of Yt is expected to increase in exp{b1} or exp{b2} times, respectively (multiplicative model). The results showed a significant exponential increase of cholera rates in humans during the study period, with an estimate of exp(b1)=1.08 (p-value = 0.02). Associations have been found between the annual increase of the air temperature in southeastern Africa and the cholera incidence in the same area. Linkages were found also for a wider scale, with the air temperature anomaly of the Southern Hemisphere, with an estimate of exp(b1)=1.18 (p-value = 0.04) and exp(b1)=1.26 (p-value = 0.006) for the previous year. Significant linkages were detected between the annual cholera rate and the annual western Indian Ocean' SST , with exp(b1) = 1.31 (p-value = 0.01) for the current year and exp(b1) = 1.23 (p-value = 0.05) for the previous year. Linkages were found also for the hemispheric scale, with the SST anomaly. The increase of global temperature may influence the temporal fluctuations of cholera, as well as potentially increasing the frequency and duration of its outbreaks. Despite future uncertainty, the climate variability has to be considered in predicting further cholera outbreaks in Africa. This may help to promote better, more efficient preparedness. For more details: Paz, S. 2010. Impact of Temperature Variability on Cholera Incidence in Southeastern Africa, 1971-2006. EcoHealth, in press.

  5. A cryogen-free variable temperature scanning tunneling microscope capable for inelastic electron tunneling spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhang, Shuai; Huang, Di; Wu, Shiwei

    While low temperature scanning tunneling microscope (STM) has become an indispensable research tool in surface science, its versatility is yet limited by the shortage or high cost of liquid helium. The makeshifts include the use of alternative cryogen (such as liquid nitrogen) at higher temperature or the development of helium liquefier system usually at departmental or campus wide. The ultimate solution would be the direct integration of a cryogen-free cryocooler based on GM or pulse tube closed cycle in the STM itself. However, the nasty mechanical vibration at low frequency intrinsic to cryocoolers has set the biggest obstacle because of the known challenges in vibration isolation required to high performance of STM. In this talk, we will present the design and performance of our home-built cryogen-free variable temperature STM at Fudan University. This system can obtain atomically sharp STM images and high resolution dI/dV spectra comparable to state-of-the-art low temperature STMs, but with no limitation on running hours. Moreover, we demonstrated the inelastic tunneling spectroscopy (STM-IETS) on a single CO molecule with a cryogen-free STM for the first time.

  6. Intraseasonal variability of air temperature over the mid-high latitude Eurasia in boreal winter

    NASA Astrophysics Data System (ADS)

    Yang, Shuangyan; Li, Tim

    2016-01-01

    The intraseasonal oscillation (ISO) of air temperature over the mid- and high-latitude Eurasia in boreal winter was investigated by NCEP-NCAR reanalysis data. It is found that the intraseasonal temperature disturbances exhibit maximum variability near the surface in the region of 50°-75°N, 80°‒120°E and they propagate southeastwards at average zonal and meridional phase speeds of 3.2 and 2.5 m s-1, respectively. The low-level temperature signal is tightly coupled with upper-tropospheric height anomalies, and both propagate southeastward in a similar phase speed. A diagnosis of the temperature budget reveals that the southeastward propagation is primarily attributed to the advection of the temperature anomaly by the mean wind. A wave activity flux analysis indicates that the southeastward propagating wave train is likely a result of Rossby wave energy propagation. The source of the Rossby wave train appears at the high latitude Europe/Atlantic sector, where maximum wave activity flux convergence resides. During its southeastward journey, the ISO perturbation gains energy from the mean flow through both kinetic and potential energy conversions. A physics-based empirical model was constructed to predict the intraseasonal temperature anomaly over southeast China. The major predictability source is the southeastward-propagating ISO signal. The data for 1979‒2003 were used as a training period to construct the empirical model. A 10-yr (2004‒2013) independent forecast shows that the model attains a useful skill of up to 25 days.

  7. Temperature Variability in the Stratosphere Obtained from 7 years of Vibrational-Raman- lidar Measurements

    NASA Astrophysics Data System (ADS)

    Iserhienrhien, B.; Sica, R. J.; Argall, P. S.

    2009-05-01

    The Purple Crow Lidar (PCL) is a large power-aperture product monostatic laser radar located at the Delaware Observatory (42° 52' N, 81° 23' W, 225 m elevation above sea level) near the campus of The University of Western Ontario. It is capable of measuring temperature and wave parameters from 10 to 110 km altitude, as well as water vapor in the troposphere and stratosphere. We use upper tropospheric and stratospheric vibrational Raman N2 backscatter-derived temperatures to form a climatology for the years 1999 to 2007 from 10 to 30 km altitude. The lidar temperatures are validated using coincident radiosondes measurements from Detroit and Buffalo. The measured temperatures show good agreement with the radiosonde soundings. An agreement of ±1 K is found during summer months and ±2.5 K during the winter months, validating the calibration of the lidar to within the geophysical variability of the measurements. Comparison between the PCL measurements and atmospheric models shows the PCL measurements are 5 K or less colder than CIRA-86 below 25 km and 2.5 K warmer above during the summer months. Below 16 km the PCL measurements are 5 K or less colder than the MSIS-90 model, while above this region, the PCL agrees to about ±3.5 K or less. The temperature differences between the PCL measurements and the models are consistent with the differences between the atmospheric models and the Detroit and Buffalo radiosonde measurements. The temperature differences compared to the models are consistent with previous comparisons between other radiosondes and satellite data sets, confirming that these differences with the models are real. We will highlight nights which show significant variations from the long-term averages, and when possible, the evolution of the variations.

  8. 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.

  9. 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.

  10. An Index of Upper Level Frontogenesis and Climate Variability of Surface Temperature

    NASA Astrophysics Data System (ADS)

    Cai, M.

    2002-12-01

    This paper proposes a potential vorticity intrusion index (denoted as PVI) as an alternative diagnostic tool to study the observed climate variability/trend of the surface temperature. The PVI index is defined as the percentage area of upper lever PV intrusion in the extratropics at any given time. Abundance (shortage) of extreme cold surface air temperature episodes in high latitudes coincides with a high (low) PVI index. The PVI index has a negative correlation with the AO index. The interannual variability of the PVI index exhibits a strong QBO- like signal. The high (low) PVI index prevails when the equatorial zonal mean zonal wind at 50 hPa is easterly (westerly). The probability distribution map of PV intrusion activities shows a shift of the preferred regions of frontogenesis from the oceans to the continents when the PVI index is high. This explains directly why more extreme cold events are observed over the northern Eurasian and Northern America continents when the PVI index is high or when the AO index is low.

  11. Linearized acoustic perturbation equations for low Mach number flow with variable density and temperature

    SciTech Connect

    Munz, Claus-Dieter . E-mail: claus-dieter.munz@iag.uni-stuttgart.de; Dumbser, Michael . E-mail: michael.dumbser@iag.uni-stuttgart.de; Roller, Sabine . E-mail: roller@hlrs.de

    2007-05-20

    When the Mach number tends to zero the compressible Navier-Stokes equations converge to the incompressible Navier-Stokes equations, under the restrictions of constant density, constant temperature and no compression from the boundary. This is a singular limit in which the pressure of the compressible equations converges at leading order to a constant thermodynamic background pressure, while a hydrodynamic pressure term appears in the incompressible equations as a Lagrangian multiplier to establish the divergence-free condition for the velocity. In this paper we consider the more general case in which variable density, variable temperature and heat transfer are present, while the Mach number is small. We discuss first the limit equations for this case, when the Mach number tends to zero. The introduction of a pressure splitting into a thermodynamic and a hydrodynamic part allows the extension of numerical methods to the zero Mach number equations in these non-standard situations. The solution of these equations is then used as the state of expansion extending the expansion about incompressible flow proposed by Hardin and Pope [J.C. Hardin, D.S. Pope, An acoustic/viscous splitting technique for computational aeroacoustics, Theor. Comput. Fluid Dyn. 6 (1995) 323-340]. The resulting linearized equations state a mathematical model for the generation and propagation of acoustic waves in this more general low Mach number regime and may be used within a hybrid aeroacoustic approach.

  12. 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

  13. Low-frequency variability of surface air temperature over the Barents Sea: causes and mechanisms

    NASA Astrophysics Data System (ADS)

    van der Linden, Eveline C.; Bintanja, Richard; Hazeleger, Wilco; Graversen, Rune G.

    2015-11-01

    The predominant decadal to multidecadal variability in the Arctic region is a feature that is not yet well-understood. It is shown that the Barents Sea is a key region for Arctic-wide variability. This is an important topic because low-frequency changes in the ocean might lead to large variations in the sea-ice cover, which then cause massive changes in the ocean-atmosphere heat exchanges. Here we describe the mechanism driving surface temperatures and heat fluxes in the Barents Sea based primarily on analyzes of one global coupled climate model. It is found that the ocean drives the low-frequency changes in surface temperature, whereas the atmosphere compensates the oceanic transport anomalies. The seasonal dependence and the role of individual components of the ocean-atmosphere energy budget are analyzed in detail, showing that seasonally-varying climate mechanisms play an important role. Herein, sea ice is governing the seasonal response, by acting as a lid that opens and closes during warm and cold periods, respectively, thereby modulating the surface heat fluxes.

  14. 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.

  15. Evaluation of spatio-temporal variability in Land Surface Temperature: A case study of Zonguldak, Turkey.

    PubMed

    Sekertekin, Aliihsan; Kutoglu, Senol Hakan; Kaya, Sinasi

    2016-01-01

    The aim of this study is to analyze spatio-temporal variability in Land Surface Temperature (LST) in and around the city of Zonguldak as a result of the growing urbanization and industrialization during the last decade. Three Landsat 5 data and one Landsat 8 data acquired on different dates were exploited in acquiring LST maps utilizing mono-window algorithm. The outcomes obtained from this study indicate that there exists a significant temperature rise in the region for the time period between 1986 and 2015. Some cross sections were selected in order to examine the relationship between the land use and LST changes in more detail. The mean LST difference between 1986 and 2015 in ERDEMIR iron and steel plant (6.8 °C), forestland (3 °C), city and town centers (4.2 °C), municipal rubbish tip (-3.9 °C), coal dump site (12.2 °C), and power plants' region (7 °C) were presented. In addition, the results indicated that the mean LST difference between forestland and city centers was approximately 5 °C, and the difference between forestland and industrial enterprises was almost 8 °C for all years. Spatio-temporal variability in LST in Zonguldak was examined in that study and due to the increase in LST, policy makers and urban planners should consider LST and urban heat island parameters for sustainable development. PMID:26666659

  16. Simultaneous U BV RI observations of the cataclysmic variable AE Aquarii: Temperatures and masses of fireballs

    NASA Astrophysics Data System (ADS)

    Zamanov , R. K.; Latev, G. Y.; Stoyanov, K. A.; Boeva, S.; Spassov, B.; Tsvetkova, S. V.

    2012-10-01

    We report simultaneous multicolour observations in 5 bands (U BV RI) of the flickering variability of the cataclysmic variable AE Aqr. Our aim is to estimate the parameters (colours, temperature, size) of the fireballs that produce the optical flares. The observed rise times of the optical flares are in the interval 220-440 s. We estimate the dereddened colours of the fireballs as (U-B)_0˜ 0.8-1.4, (B-V)_0 ˜ 0.03-0.24, and (V-I)_0 ˜ 0.26-0.78. We find for the fireballs temperatures of 10000-25000 K, masses of (7-90)× 1019 g, and sizes of (3-7)× 109 cm (using a distance of d=86 pc). These values refer to the peak of the flares observed in the U BV RI bands. The data are available upon request from the authors. Based on data collected with the telescopes at Bulgarian National Astronomical Observatory Rozhen and Belogradchick Astronomical Observatory.

  17. Human factors - recognising and minimising errors in our day to day practice.

    PubMed

    Green, B; Tsiroyannis, C; Brennan, P A

    2016-01-01

    A significant cause of mistakes in healthcare and which are potentially harmful or fatal to patients can result from both individual clinicians and their employing organisations. The understanding and recognition of the role of human error within the healthcare setting is improving, but we still have much to learn when compared with other high-risk organisations such as aviation where such errors can be devastating at a much larger scale. The importance of both organisational issues and human factor issues at a more personal level including tiredness, the effect of emotions and the role of situational awareness, needs to be understood by all those involved in healthcare. Potential mistakes can be reduced with simple measures which need to be recognised by, emphasised and embedded in both teams and individuals. In this review, we address the need for greater awareness of human factors, assessing the path to error and how this can be reduced to minimum levels in clinical practice. PMID:26500041

  18. Carbohydrate balance and the regulation of day-to-day food intake in humans.

    PubMed

    Stubbs, R J; Murgatroyd, P R; Goldberg, G R; Prentice, A M

    1993-06-01

    The hypothesis that carbohydrate stores are an important determinant of voluntary food intake was tested by covert dietary manipulation of carbohydrate stores in nine men during 2 d of continuous whole-body calorimetry that provided half-hourly monitoring of energy and fuel balance. On day 1 subjects were fed diets intended to maintain energy balance but containing carbohydrate at either 3% (depletion) or 47% (control) energy. Average carbohydrate balance changed by 153 +/- 42 g (mean +/- SD). Subsequent (day 2) ad libitum food intake from a normal diet of fixed macronutrient composition was identical on the control and depletion protocols: 12.73 +/- 2.24 and 12.72 +/- 2.01 MJ, respectively. The carbohydrate-depletion protocol caused a suppression of carbohydrate oxidation (174 +/- 41 vs 256 +/- 39 g, P < 0.001) and a reciprocal elevation in fat oxidation (120 +/- 11 vs 89 +/- 12 g, P < 0.001). These readjustments in fuel utilization were the primary mechanism for re-establishing carbohydrate balance. This study does not support the hypothesis that the need to maintain specific carbohydrate stores is a determinant of food intake in the short term. PMID:8503359

  19. The Day-to-Day Work of Primary School Teachers: A Source of Professional Learning

    ERIC Educational Resources Information Center

    Ambler, Trudy Belinda

    2016-01-01

    Teachers are an important influence on students' learning, and therefore the opportunity for teachers to learn and develop is something of interest to educators internationally. This article reports on a research project involving six primary school teachers who participated in one-on-one and small group interviews to explore the opportunities for…

  20. Characteristics of high energy cosmic ray diurnal anisotropy on day-to-day basis

    NASA Astrophysics Data System (ADS)

    Tiwari, C. M.; Tiwari, D. P.

    2008-10-01

    Diurnal variation of cosmic ray intensity for the period of 1989 to 2000 at Kiel, Haleakakla, Rome, Hermanus, Calgary, and Goose Bay neutron monitors has been studied. Frequency histograms are generated for each year by using the daily values of amplitudes and phases. In the present analysis we have derived the yearly mean amplitude and phase of the diurnal variation of cosmic ray intensity. It has been concluded from the analysis that the diurnal amplitude is mostly concentrated in between the amplitude values of 0.1% and 0.4%, whereas the phase of diurnal anisotropy is concentrated in the belt of 100 to 225 degrees. As such, the various characteristics of long-term diurnal variation of cosmic ray intensity for the maxima of solar activity cycle 22 to the next maxima of solar activity cycle 23 have been studied. The minimum amplitudes are apparent for the minimum solar activity periods starting from 1995 and up to 1997 at Kiel, Haleakakla, Rome, Hermanus, Calgary and Goose Bay stations. The diurnal amplitude has been found to have almost recovered to its values observed during 1989 to 1990. It is also seen that the diurnal amplitudes are much larger by a factor of two at high/middle latitude stations as compared to that for low latitude stations, where the amplitudes are even ˜01% or less during 1996. The phase is significantly earlier during 1996 and 1997 with some significant change starting in 1995. As such, competitive is a continuous decreasing trend in the diurnal phase with smaller change at high/middle latitude and significantly much larger change at low latitudes.

  1. Atmospheric Dynamical Responses to Solar Wind Variations on the Day-to-Day Timescale

    NASA Astrophysics Data System (ADS)

    Tinsley, B. A.

    2001-12-01

    In the early 1970s it was shown by John Wilcox and associates and verified by Colin Hines that the strength of winter storms across the northern hemisphere decreases at times of solar wind 'sector boundary' crossings. These are now known as heliospheric current sheet (HCS) crossings, and correspond to the extension of the coronal streamer belt passing over the Earth, with reductions in solar wind velocity by about 10%. The strength of winter storms is objectively evaluated by the vorticity area index (VAI) calculated from gridded geopotential height data sets. It was shown by Tinsley, Hoeksema, Baker and Kirkland in the mid-1990s that this VAI response (the Wilcox effect) tracks the decrease in MeV electron flux precipitating from the magnetosphere, with a lag of less than a day. The MeV electron flux is strongly correlated with solar wind velocity, and together with its associated X-ray Bremsstrahlung modulates the stratospheric vertical column resistance. For winters when the column resistance is unusually high because of a high mixing ratio of H2SO4 from volcanic eruptions, the ionosphere-earth current density Jz is modulated by these stratospheric resistance variations. The winter storm response can be understood in terms of a general theory (Tinsley, Space Sci. Rev., 94, 231-258, 2000), and it involves changes in cloud microphysics and precipitation from the storm systems at mid-high geomagnetic latitudes, due to electroscavenging by cloud droplets. The electroscavenging rate tracks the Jz changes. There is a similar effect from reductions in tropospheric resistance associated with changes in cosmic ray flux during magnetic storms, first noticed in the 1960s by Walter Orr Roberts and associates. The Roberts and Wilcox effects are part of a more general influence of solar activity affecting Jz and clouds, which is part of an even more general influence of electroscavenging on clouds. The precipitation changes associated with cosmic ray and Jz changes have been evaluated by Kniveton and Todd (GRL 28, 1527-1530 and 3279). In winter storms the VAI response arises from a redistribution of vorticity within the storm because of diabatic heating changes. The storm vorticity changes have longer term dynamical and climatic consequences. >http://www.utdallas.edu/dept/physics/Faculty/tinsley/tinsley.htm

  2. Individual Day-to-Day Process of Social Anxiety in Vulnerable College Students

    ERIC Educational Resources Information Center

    Campbell, Cynthia G.; Bierman, Karen L.; Molenaar, Peter C. M.

    2016-01-01

    Transitions requiring the creation of new social networks may be challenging for individuals vulnerable to social anxiety, which may hinder successful adjustment. Using person-specific methodology, this study examined social anxiety in vulnerable university freshman away from home during their first semester of college to understand how day-to-day…

  3. Making It Day-to-Day: A New Family Income Standard for Arkansas [and] Executive Summary.

    ERIC Educational Resources Information Center

    Huddleston, Rich

    This report examines the financial needs of Arkansas families, and establishes, using conservative economic assumptions, an annual Family Income Standard (FIS) for the state and each of its counties. The FIS is a new tool to be used by citizens, state and local policy makers, civic organizations, non-profits, and parents as they look to improve

  4. "I just cope from day to day": unpredictability and anxiety in the lives of women.

    PubMed

    Walters, V; Charles, N

    1997-12-01

    Data are presented from in-depth interviews with 35 women in an industrial town in South Wales, U.K., many of whom were from low income households. The research aimed to explore women's own concerns about their health and the ways in which health problems affected their lives. This paper focuses on one prominent theme in these interviews: unpredictability. In particular, women described how their lives had become less predictable and amenable to control as a result of health problems--epilepsy, asthma, ME, anxiety, nerves and panic attacks, for example. Women's accounts are used to show how they experienced these problems, how they influenced women's self-identity and the ways in which women struggled to cope with the dreadful uncertainty that characterized their days. They often hid these problems, and the privacy of this aspect of their lives is striking. The data are set within the context of class and gender relations which diminish women's control over their lives and erode their self-esteem and sense of autonomy. Class and gender combine with ill health to create the conditions for women's sense of unpredictability and powerlessness. They can aggravate and provoke the health problems women described: women spoke of the challenges they faced in their roles as wives and mothers, the problems associated with widowhood, the loss of their jobs, the impact of unemployment and their efforts to cope with severe financial problems. In part, these provided them with a framework for understanding the uncertainty, anxiety, nerves and panic they experienced. PMID:9428091

  5. Day-to-day care: the interplay of CNAs' views of residents & nursing home environments.

    PubMed

    Fisher, Lucy Takesue; Wallhagen, Margaret I

    2008-11-01

    This qualitative study identified certified nursing assistants' (CNAs') perspectives of nursing home residents and how these perspectives translate into care practices. Data included observations of and interviews with 27 CNAs in three dissimilar nursing homes. All participants were people of color, and all but 3 were immigrants. CNAs constructed three views of residents: as fictive kin, as a commodity, and as an autonomous person. Although individual CNAs held one primary view of residents in general, select residents were viewed from an alternative perspective, resulting in variations in care practices. These findings suggest that such distinctions, in tandem with structural, organizational, and cultural differences in nursing homes, present opportunities for nursing leadership to affect the visible, everyday practice of nursing CNAs. To target interventions, further research is needed on how CNAs come to differentially view residents and how these differences influence CNAs' care relationships with residents. PMID:19024427

  6. Day to Day...Parent to Child. The Future of Violence among Homeless Children in America.

    ERIC Educational Resources Information Center

    Homes for the Homeless, Inc., New York, NY.

    The majority of parents now living in homeless shelters, typically young single mothers with one or two children under the age of six, have spent their lives spiraling downward through a complex and self-perpetuating cycle of family violence, community violence, and poverty. Sixty-three percent of homeless parents, a survey has found, live with…

  7. "Living from day to day": food insecurity, complexity, and coping in muTare, Zimbabwe.

    PubMed

    Gwatirisa, Pauline; Manderson, Lenore

    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, southeast Zimbabwe, in 2005-2006, the authors illustrate the flow-on effects of drought and government policy on the livelihoods of households already suffering as a result of the social impacts of AIDS, and how people in a regional city responded to these factors, defining and meeting their basic food needs in diverse ways. PMID:22455860

  8. Climatic variability of river outflow in the Pantanal region and the influence of sea surface temperature

    NASA Astrophysics Data System (ADS)

    Silva, Carlos Batista; Silva, Maria Elisa Siqueira; Ambrizzi, Tércio

    2016-03-01

    This paper investigates possible linear relationships between climate, hydrology, and oceanic surface variability in the Pantanal region (in South America's central area), over interannual and interdecadal time ranges. In order to verify the mentioned relations, lagged correlation analysis and linear adjustment between river discharge at the Pantanal region and sea surface temperature were used. Composite analysis for atmospheric fields, air humidity flux divergence, and atmospheric circulation at low and high levels, for the period between 1970 and 2003, was analyzed. Results suggest that the river discharge in the Pantanal region is linearly associated with interdecadal and interannual oscillations in the Pacific and Atlantic oceans, making them good predictors to continental hydrological variables. Considering oceanic areas, 51 % of the annual discharge in the Pantanal region can be linearly explained by mean sea surface temperature (SST) in the Subtropical North Pacific, Tropical North Pacific, Extratropical South Pacific, and Extratropical North Atlantic over the period. Considering a forecast approach in seasonal scale, 66 % of the monthly discharge variance in Pantanal, 3 months ahead of SST, is explained by the oceanic variables, providing accuracy around 65 %. Annual discharge values in the Pantanal region are strongly related to the Pacific Decadal Oscillation (PDO) variability (with 52 % of linear correlation), making it possible to consider an interdecadal variability and a consequent subdivision of the whole period in three parts: 1st (1970-1977), 2nd (1978-1996), and 3rd (1997-2003) subperiods. The three subperiods coincide with distinct PDO phases: negative, positive, and negative, respectively. Convergence of humidity flux at low levels and the circulation pattern at high levels help to explain the drier and wetter subperiods. During the wetter 2nd subperiod, the air humidity convergence at low levels is much more evident than during the other two drier subperiods, which mostly show air humidity divergence. While the drier periods are particularly characterized by the strengthening of northerly wind over the center of South America, including the Pantanal region, the wetter period is characterized by its weakening. The circulation pattern at 850 hPa levels during the drier subperiods shows anticyclonic anomalies centered over east central South America. Also, the drier subperiods (1st and 3rd) are characterized by negative stream function anomalies over southeastern South America and adjacent South Atlantic, and the wetter subperiod is characterized by positive stream function anomalies. In the three subperiods, one can see mean atmospheric patterns associated with Rossby wave propagation coming from the South Pacific basin—similar to the Pacific South America pattern, but with reverse signals between the wetter and the drier periods. This result suggests a possible relationship between climatic patterns over southeastern South America regions and the Pacific conditions in a decadal scale.

  9. Mechanisms of observed sea surface temperature variability in the extratropical Southern Hemisphere

    NASA Astrophysics Data System (ADS)

    Ciasto, Laura M.

    The physical mechanisms that drive sea surface temperature (SST) variability in the extratropical Southern Hemisphere (SH) are examined using multiple ocean temperature datasets. The first part of the study provides a detailed analysis of the relationships between variability in SH SST anomalies, the Southern Annular Mode (SAM) and the El-Nino/Southern Oscillation (ENSO) during the warm (November-April) and cold (May-October) seasons. It is shown that the signatures of the SAM and ENSO in the SST field vary as a function of season, both in terms of their amplitudes and structures. SAM-related SST anomalies are primarily driven by surface turbulent heat fluxes with a smaller contribution from heat advection by Ekman currents. The role of turbulent heat fluxes in generating ENSO-related SST anomalies is less clear. Analyses of the temporal evolution of the relationships between the SAM and the SST field demonstrate that SST anomalies are largest when SSTs lag by ˜1 week and persist for up to 8 weeks. In the absence of ENSO, cold season SAM-related SST anomalies persist longer than their warm season counterparts, consistent with seasonal variations in the depth of the mixed layer. The second part of the study uses observations of subsurface temperatures to examine the winter-to-winter "reemergence" of SST anomalies in the extratropical South Pacific. Reemergence is the mechanism whereby SST anomalies formed in the late winter are sequestered beneath the shallow summer mixed layer and then re-entrained into the deepening mixed layer during the following fall/winter. The results exhibit a pronounced reemergence signal in which surface temperature anomalies during the late winter season are strongly correlated with surface temperature anomalies during the subsequent early winter months, but are only significantly correlated with temperature anomalies beneath the mixed layer during the intervening summer months. The results are robust to small changes in the period of analysis and are qualitatively similar to existing evidence of reemergence in the Northern Hemisphere. The signal of reemergence evident in the subsurface data is readily apparent in SST data in the western South Pacific. Reemergence is less evident in SST data in the eastern South Pacific.

  10. The signatures of large-scale patterns of atmospheric variability in Antarctic surface temperatures

    NASA Astrophysics Data System (ADS)

    Marshall, Gareth J.; Thompson, David W. J.

    2016-04-01

    We investigate the impact that the four principal large-scale patterns of Southern Hemisphere (SH) atmospheric circulation variability have on Antarctic surface air temperature (SAT): (1) the southern baroclinic annular mode (BAM), which is associated with variations in extratropical storm amplitude; (2) the Southern Annular Mode (SAM), associated with latitudinal shifts in the midlatitude jet; and (3) the two Pacific-South American patterns (PSA1 and PSA2), which are characterized by wave trains originating in the tropical Pacific that extend across the SH extratropics. A key aspect is the use of 35 years of daily observations and reanalysis data, which affords a sufficiently large sample size to assess the signatures of the circulation patterns in both the mean and variability of daily mean SAT anomalies. The BAM exerts the weakest influence on Antarctic SAT, albeit it is still important over select regions. Consistent with previous studies, the SAM is shown to influence SAT across most of the continent throughout the year. The PSA1 also affects SAT across almost all of Antarctica. Regionally, both PSA patterns can exert a greater impact on SAT than the SAM but also have a significantly weaker influence during summer, reflecting the seasonality of the SH response to El Niño-Southern Oscillation. The SAM and PSA patterns have distinct signatures in daily SAT variance that are physically consistent with their signatures in extratropical dynamic variability. The broad-scale climate linkages identified here provide benchmarks for interpreting the Antarctic climate response to future changes in tropical sea surface temperatures, ozone recovery, and greenhouse gas increases.

  11. Variability of North Atlantic surface and subsurface temperatures during the last 2000 years

    NASA Astrophysics Data System (ADS)

    Bouinot, T.; Cortijo, E.; Govin, A.; Cléroux, C.; Mulder, T.; Gonthier, E.

    2010-12-01

    The Atlantic Meridional Overturning Circulation (AMOC) is an important component for oceanic heat transport from low to high latitudes; most of this ocean heat is mainly contained in the first few hundred meters of the water column. Recent oceanographic measurements show that AMOC fluctuated in a decadal period of time. The causes of these fluctuations are still poorly understood, and available observations are too limited in time (only the last decades) to properly investigate all the mechanisms responsible for these fluctuations. The aim of this work is to reconstruct variability of past sea surface and subsurface temperatures in order to extend the information available from observations on the ocean heat content fluctuations. This work is part of the European project THOR (Thermohaline Overturning - at Risk?). We studied the IMAGES core MD08-3182 (52°41.99’N 35°56.15’W, 3757m) located in the main pathway of the Gulf Stream (GS) in the Charlie Gibbs Fracture Zone, a key location for monitoring the subpolar gyre dynamics. We also use the IMAGES MD99-2203 core (34°58,38N-620m) located off Cape Hatteras, a suitable location to record the variability of the GS. A third core CADI2KS12 (36°42,79’-1120m) in the Gulf of Cádiz monitors the return current of the subtropical gyre. All these cores are radiocarbon dated by AMS. The upper water column characteristics are reconstructed by geochemical analysis: paired measurements of oxygen isotopic composition and trace elements ratio (Mg/Ca) in Planktonic foraminifera have been used to reconstruct temperature and oxygen isotopic composition of sea water (δ18Osw). Both surface and deep-dwelling species (at the base of the seasonal thermocline) have been measured in order to obtain a complete temperature and δ18Osw record over the first few hundred meters of the water column. We have reconstructed the sea temperature variability of the water column during the Late Holocene, in particular the last 2000 years. These results enable us to think to a significative oceanic circulation change during the Medieval Climatic Anomaly.

  12. Multidecadal variability of potential temperature, salinity, and transport in the eastern subpolar North Atlantic

    NASA Astrophysics Data System (ADS)

    Holliday, N. P.; Cunningham, S. A.; Johnson, C.; Gary, S. F.; Griffiths, C.; Read, J. F.; Sherwin, T.

    2015-09-01

    The Extended Ellett Line (EEL) hydrographic section extends from Scotland to Iceland crossing the Rockall Trough, Hatton-Rockall Basin, and Iceland Basin. With 61 full-depth stations at a horizontal resolution of 10-50 km, the EEL samples the upper limb of the Atlantic Meridional Overturning Circulation flowing across the Iceland-Scotland Ridge into the Nordic Seas. The Rockall Trough has been sampled nearly four times per year from 1975 to 1996, and the full section annually since 1996. The EEL is an exceptionally long-time series of deep ocean temperatures and salinities. This study extends prior work in the Rockall Trough, and examines for the first time 18 year records in the Iceland and Hatton-Rockall Basins. We quantify errors in the time series from two sources: observational errors and aliasing. The data quality and annual sampling are suitable for observing interannual to decadal variability because the variability exceeds our error estimates. The upper waters of all three basins are cooler/fresher from 1997 to 2001, warmer/more saline 2001-2006, and cooler/fresher from 2006 to 2014. A reference level for geostrophic shear is developed heuristically and by comparison with sea-surface altimetry. The mean northward transport in the upper waters is 6.7 ± 3.7 Sv and there is a 6.1 ± 2.5 Sv southward flow below the thermocline. Although the magnitude of the Iceland Basin overturning circulation (4.3 ± 1.9 Sv) is greater than in the Rockall Trough (3.0 ± 3.7 Sv), the variability is greater in the Rockall Trough. We discuss the results in the context of our understanding of drivers of variability.

  13. Spatiotemporal Variability of NDVI Over Indian Region and its Relationship with Rainfall, Temperature, Soil moisture, and Sea Surface Temperature

    NASA Astrophysics Data System (ADS)

    Akarsh, A.; Mishra, V.

    2014-12-01

    The Normalized difference Vegetation Index (NDVI) is considered as a proxy for vegetation health. Worldwide it is used as an effective tool to monitor spatiotemporal variations in land use practices and vegetation vigor. The forecast of NDVI can be effectively utilized as an early warning system for the better planning and management, especially in agricultural sector. Here, in this study, we evaluated the spatiotemporal variability of NDVI over Indian region and how it is affected by various factors such as rain fall, temperature, sea surface temperature (SST) and soil moisture. First, we evaluated the seasonal (Pre monsoon, Monsoon, Post Monsoon, Kharif and Rabi) NDVI trend from 1982-2013 and it is found that there is a significant increase in NDVI over the Indian region in land use land cover (LULC) classes. Further the correlation analysis of NDVI with above mention parameters were performed at various lags to evaluate better predictor of NDVI and it is observed that all the parameters exhibit significantly high correlations at various lags. It is well known that over the Indian region vegetation growth/crop growth is largely dependent on climate parameters especially rainfall, and Indian region rainfall is highly correlated with El Nino/Southern Oscillation (ENSO). Thus the relationship of NDVI with SST one of the proxies of ENSO can be utilized to predict vegetation health over Indian region. To evaluate that we performed Maximum Covariance Analysis (MCA) of SST departure field and NDVI time series and found that there exists a decline in vegetation health or NDVI if the equatorial eastern pacific SST is anomalously high.

  14. Atmospheric controls on northeast Pacific temperature variability and change, 1900-2012.

    PubMed

    Johnstone, James A; Mantua, Nathan J

    2014-10-01

    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

  15. 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

  16. 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

  17. Hydrolysis of neptunium(V) at variable temperatures (10 85°C)

    NASA Astrophysics Data System (ADS)

    Rao, Linfeng; Srinivasan, Thandankorai G.; Garnov, Alexander Yu; Zanonato, PierLuigi; Di Bernardo, Plinio; Bismondo, Arturo

    2004-12-01

    Neptunium is one of the few radioactive elements that are of great concern in the disposal of nuclear wastes in the geological repository, due to its hazards and the long half-life of the isotope, 237Np ( t1/2 = 2.14 × 10 6 years). To understand and predict the migration behavior of neptunium in the geological media, it is of importance to study its hydrolysis at elevated temperatures, because the temperature in the waste package and the vicinity of the repository could be high. Moreover, the chemical analogy between neptunium(V) and plutonium(V) adds even greater value to this investigation, because the latter could exist at tracer levels in neutral and slightly oxidizing waters but is difficult to study due to its rather labile redox behavior. In this work, the hydrolysis of neptunium(V) was studied at variable temperatures (10 to 85°C) in tetramethylammonium chloride (1.12 mol kg -1). Two hydrolyzed species of neptunium(V), NpO 2OH(aq) and NpO 2(OH) 2-, were identified by potentiometry and Near-IR absorption spectroscopy. The hydrolysis constants (* βn) and enthalpy of hydrolysis (Δ Hn) for the reaction NpO 2+ + nH 2O = NpO 2(OH) n(1-n)+ + nH + ( n = 1 and 2) were determined by titration potentiometry and microcalorimetry. The hydrolysis constants, * β1 and * β2, increased by 0.8 and 3.4 orders of magnitude, respectively, as the temperature was increased from 10 to 85°C. The enhancement of hydrolysis at elevated temperatures is mainly due to the significant increase of the degree of ionization of water as the temperature is increased. The hydrolysis reactions are endothermic but become less endothermic as the temperature is increased. The heat capacities of hydrolysis, Δ Cp1 and Δ Cp2 , are calculated to be -(71 ± 17) J K -1 mol -1 and -(127 ± 17) J K -1 mol -1, respectively. Approximation approaches to predict the effect of temperature, including the constant enthalpy approach, the constant heat capacity approach and the DQUANT equation, have been tested with the data.

  18. Assessment of the temperature variability at the snow-ground interface - concept and first results

    NASA Astrophysics Data System (ADS)

    Hiller, Clemens; Keuschnig, Markus; Hartmeyer, Ingo; Götz, Joachim

    2014-05-01

    Bottom temperatures of the winter snow cover (BTS) represent the thermal conditions at the snow-ground interface and serve as a proxy for local permafrost ocurrence. The BTS method has been used in numerous studies to investigate local permafrost evidence and to validate larger scale permafrost distribution models. However, former studies have shown a relatively strong scattering between single measurements indicating that BTS values are sensitive to further factors. In order to identify the spatial and temporal variability and mentioned sources of irritation and to better understand their influence we applied repeated BTS measurements on a small scale test site situated below the Maurerkogel (2990 m) nearby the Kitzsteinhorn, Hohe Tauern Range, Austria. The site (c. 2000 m2) shows fairly homogenous surface conditions in terms of roughness and morphometry (bedrock with thin layer of fine-grained talus, slightly inclined to N). The measurement setup consists of a BTS grid with a minimum spacing of 5 m. Four campaigns with a total of 94 measurements were carried out from March 2012 to April 2013. Universal Temperature Logger (UTL), snow profiles and meteorological data from automatic weather stations are used to interpret the BTS values. The standard deviations of BTS values for each campaign range between 0.4 and 0.9 °C. The mean BTS value within the overall period is -3.1 °C. The near surface temperature logger shows a mean temperature of -3.7 °C in 10 cm depth covering four campaign days. Both, the correlation between near surface temperatures and BTS values as well as the low standard deviation between the BTS values demonstrate the applicability of the method under appropriate conditions.

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

    NASA Astrophysics Data System (ADS)

    Saenger, Casey; Affek, Hagit P.; Felis, Thomas; Thiagarajan, Nivedita; Lough, Janice M.; Holcomb, Michael

    2012-12-01

    Geochemical variations in shallow water corals provide a valuable archive of paleoclimatic information. However, biological effects can complicate the interpretation of these proxies, forcing their application to rely on empirical calibrations. Carbonate clumped isotope thermometry (Δ47) is a novel paleotemperature proxy based on the temperature dependent "clumping" of 13C-18O bonds. Similar Δ47-temperature relationships in inorganically precipitated calcite and a suite of biogenic carbonates provide evidence that carbonate clumped isotope variability may record absolute temperature without a biological influence. However, large departures from expected values in the winter growth of a hermatypic coral provided early evidence for possible Δ47 vital effects. Here, we present the first systematic survey of Δ47 in shallow water corals. Sub-annual Red Sea Δ47 in two Porites corals shows a temperature dependence similar to inorganic precipitation experiments, but with a systematic offset toward higher Δ47 values that consistently underestimate temperature by ˜8 °C. Additional analyses of Porites, Siderastrea, Astrangia and Caryophyllia corals argue against a number of potential mechanisms as the leading cause for this apparent Δ47 vital effect including: salinity, organic matter contamination, alteration during sampling, the presence or absence of symbionts, and interlaboratory differences in analytical protocols. However, intra- and inter-coral comparisons suggest that the deviation from expected Δ47 increases with calcification rate. Theoretical calculations suggest this apparent link with calcification rate is inconsistent with pH-dependent changes in dissolved inorganic carbon speciation and with kinetic effects associated with CO2 diffusion into the calcifying space. However, the link with calcification rate may be related to fractionation during the hydration/hydroxylation of CO2 within the calcifying space. Although the vital effects we describe will complicate the interpretation of Δ47 as a paleothermometer in shallow water corals, it may still be a valuable paleoclimate proxy, particularly when applied as part of a multi-proxy approach.

  20. Thermocline Temperature Variability Reveals Shifts in the Tropical Pacific Mean State across Marine Isotope Stage 3

    NASA Astrophysics Data System (ADS)

    Hertzberg, J. E.; Schmidt, M. W.

    2014-12-01

    The eastern equatorial Pacific (EEP) is one of the most dynamic oceanographic regions, making it a critical area for understanding past climate change. Despite this, there remains uncertainty on the climatic evolution of the EEP through the last glacial period. According to the ocean dynamical thermostat theory, warming (cooling) of the tropical Pacific Ocean may lead to a more La Niña (El Niño)-like mean state due to zonally asymmetric heating and subsequent easterly (westerly) wind anomalies at the equator (Clement and Cane, 1999). Attempts to understand these feedbacks on millennial timescales across Marine Isotope Stage 3 (MIS 3) have proven to be fruitful in the western equatorial Pacific (WEP) (Stott et al., 2002), yet complimentary, high-resolution records from the EEP are lacking. To provide a more complete understanding of the feedback mechanisms of the dynamical thermostat across periods of abrupt climate change, we reconstruct thermocline temperature variability across MIS 3 from a sediment core located in the EEP, directly within the equatorial cold tongue upwelling region (core MV1014-02-17JC). Temperature anomalies in thermocline waters of the EEP are integrally linked to the ENSO system, with large positive and negative anomalies recorded during El Niño and La Niña events, respectively. Mg/Ca ratios in the thermocline-dwelling planktonic foraminifera Neogloboquadrina dutertrei were measured at 2 cm intervals, resulting in a temporal resolution of <200 years. Preliminary results across Interstadials 5-7 reveal warmer thermocline temperatures (an increase in Mg/Ca of .25 ± .02 mmol/mol) during periods of cooling following peak Interstadial warmth over Greenland, as seen from the NGRIP δ18O record. Thus, periods of cooling over Greenland appear to correspond to an El Niño-like mean state in the tropical Pacific, in line with predictions of an ocean dynamical thermostat. Interestingly, Heinrich Event 3 corresponds to cooler thermocline temperatures, suggesting a different forcing mechanism of tropical Pacific mean state variability across Heinrich Events. The record will be extended back to 80 kyr BP, and we will also measure Globigerinoides ruber Mg/Ca ratios across MIS 3 to calculate the zonal E-W sea surface temperature gradient using published records from the WEP.

  1. Zonal and Meridional Sea Surface Temperature Gradients and Orbital Variability During the Plio-Pleistocene Transition

    NASA Astrophysics Data System (ADS)

    Lawrence, K. T.; Cleaveland, L. C.; Mulligan, A. B.; Herbert, T. D.

    2007-12-01

    As the most recent interval of sustained warmth in Earth's history the Pliocene represents a potential analog for future climate scenarios. Yet, the ultimate causes of both early Pliocene warmth and the subsequent major climatic transition, which resulted in the development of large ice sheets in the Northern Hemisphere, remain unclear. Here, we compare and contrast three orbital-resolution, alkenone-derived sea surface temperature (SST) records for the interval from 4 to 1.4 Ma, shedding new light on the evolution of the ocean surface temperature field during the Plio-Pleistocene Transition. We examine the trends and orbital scale variability as well as the zonal and meridional temperature gradients elucidated by SST data from Ocean Drilling Program Site 846 (3°S, 91°W) in the eastern equatorial Pacific (EEP), Site 982 (58°N, 16°W) in the North Atlantic, and Site 662 (1°S, 12°W) in the Eastern Equatorial Atlantic (EE ATL). Our data indicate that although the rate of cooling in the EEP (1°C/Myr) was nearly twice that in the EE ATL (0.6°C/Myr), the overall structure of the data from these two sites is remarkably similar. This marked similarity in structure suggests the operation of a large-scale forcing mechanism, such as a change in atmospheric CO2 concentrations. The zonal temperature gradient between our two tropical sites grew steadily from <1°C at 4 Ma to ~2°C at 1.4 Ma, perhaps as a result of strengthening Walker circulation in the equatorial Pacific. The North Atlantic meridional temperature gradient was ~8°C between 4 and 3.5 Ma and grew steadily to ~12°C at 2.5 Ma when it plateaued until the end of the record at 1.4 Ma. Not surprisingly, the variance at our high latitude site is much greater than that at our tropical sites. However, the presence of significant variance at Site 982 prior to the intensification of Northern Hemisphere Glaciation (~2.75 Ma) is anomalous given the very small amplitude of variations in all other climatic time series from this time period. Obliquity variations are notable in all three records. Significant obliquity variability exists throughout the Site 982 time series while the obliquity response at both tropical sites increases markedly at ~2.7 Ma. In contrast to the minor role of precessional variations at Site 846 and Site 982, precession played very prominent role at Site 662, likely related to variations in the strength of the African monsoon system.

  2. Improved VAS regression soundings of mesoscale temperature structure observed during the 1982 atmospheric variability experiment

    NASA Technical Reports Server (NTRS)

    Chesters, Dennis; Keyser, Dennis A.; Larko, David E.; Uccellini, Louis W.

    1987-01-01

    An Atmospheric Variability Experiment (AVE) was conducted over the central U.S. in the spring of 1982, collecting radiosonde date to verify mesoscale soundings from the VISSR Atmospheric Sounder (VAS) on the GOES satellite. Previously published VAS/AVE comparisons for the 6 March 1982 case found that the satellite retrievals scarcely detected a low level temperature inversion or a mid-tropospheric cold pool over a special mesoscale radiosonde verification network in north central Texas. The previously published regression and physical retrieval algorithms did not fully utilize VAS' sensitivity to important subsynoptic thermal features. Therefore, the 6 March 1982 case was reprocessed adding two enhancements to the VAS regression retrieval algorithm: (1) the regression matrix was determined using AVE profile data obtained in the region at asynoptic times, and (2) more optimistic signal-to-noise statistical conditioning factors were applied to the VAS temperature sounding channels. The new VAS soundings resolve more of the low level temperature inversion and mid-level cold pool. Most of the improvements stems from the utilization of asynoptic radiosonde observations at NWS sites. This case suggests that VAS regression soundings may require a ground-based asynoptic profiler network to bridge the gap between the synoptic radiosonde network and the high resolution geosynchronous satellite observations during the day.

  3. Design Analysis of a High Temperature Radiator for the Variable Specific Impulse Magnetoplasma Rocket (VASIMR)

    NASA Technical Reports Server (NTRS)

    Sheth, Rubik B.; Ungar, Eugene K.; Chambliss, Joe P.; Cassady, Leonard D.

    2011-01-01

    The Variable Specific Impulse Magnetoplasma Rocket (VASIMR), currently under development by Ad Astra Rocket Company, is a unique propulsion system that can potentially change the way space propulsion is performed. VASIMR's efficiency, when compared to that of a conventional chemical rocket, reduce propellant needed for exploration missions by a factor of 10. Currently plans include flight tests of a 200 kW VASIMR system, titled VF-200, on the International Space Station. The VF-200 will consist of two 100 kW thruster units packaged together in one engine bus. Each thruster unit has a unique heat rejection requirement of about 27 kW over a firing time of 15 minutes. In order to control rocket core temperatures, peak operating temperatures of about 300 C are expected within the thermal control loop. Design of a high temperature radiator is a unique challenge for the vehicle design. This paper will discuss the path taken to develop a steady state and transient based radiator design. The paper will describe radiator design options for the VASIMR thermal control system for use on ISS as well as future exploration vehicles.

  4. Dinitrogen and carbon monoxide hydrogen bonding in protonic zeolites: Studies from variable-temperature infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Otero Areán, C.

    2008-05-01

    Adsorption (at a low temperature) of nitrogen on the protonic zeolite H-Y results in hydrogen bonding of the adsorbed N 2 molecules with the zeolite Si(OH)Al Brønsted-acid groups. This hydrogen-bonding interaction leads to activation, in the infrared, of the fundamental N-N stretching mode, which appears at 2334 cm -1. From infrared spectra taken over a temperature range, the standard enthalpy of formation of the OH···N 2 complex was found to be Δ H0 = -15.7(±1) kJ mol -1. Similarly, variable-temperature infrared spectroscopy was used to determine the standard enthalpy change involved in formation of H-bonded CO complexes for CO adsorbed on the zeolites H-ZSM-5 and H-FER; the corresponding values of Δ H0 were found to be -29.4(±1) and -28.4(±1) kJ mol -1, respectively. The whole set of results was analysed in the context of other relevant data available in the literature.

  5. Variable Temperature Current-Voltage Measurements of CdTe Solar Cells

    NASA Astrophysics Data System (ADS)

    Smith, A. D.

    2000-03-01

    We have used a 2" x 2" Peltier heat pump chip powered with 24 V from a computer power supply to build a variable temperature stage for current voltage measurements of solar cells. A voltage divider was used to achieve several different set point temperatures from 25 oC to -24 oC. This system was used with a halogen lamp to study the electrical performance of polycrystalline thin-film solar cells fabricated in our group. These cells have the superstrate structure glass/SnO2:F/CdS/CdTe/metal.(1) The I-V characteristic shows evidence of a blocking back-diode which sets in below room temperature. This behavior will be related to the diffusion into the CdTe of the metals used for our back contact.(2) 1. M. Shao, A. Fischer, D. Grecu, U. Jayamaha, E. Bykov, G. Contreras-Puente, R.G. Bohn, and A.D. Compaan, Appl. Phys. Lett. 69, 3045-3047 (1996). 2. D. Grecu and A.D. Compaan, Appl. Phys. Lett. 75, 361-363 (1999).

  6. Variable relationship between accumulation and temperature in West Antarctica for the past 31,000 years

    NASA Astrophysics Data System (ADS)

    Fudge, T. J.; Markle, Bradley R.; Cuffey, Kurt M.; Buizert, Christo; Taylor, Kendrick C.; Steig, Eric J.; Waddington, Edwin D.; Conway, Howard; Koutnik, Michelle

    2016-04-01

    The Antarctic contribution to sea level is a balance between ice loss along the margin and accumulation in the interior. Accumulation records for the past few decades are noisy and show inconsistent relationships with temperature. We investigate the relationship between accumulation and temperature for the past 31 ka using high-resolution records from the West Antarctic Ice Sheet (WAIS) Divide ice core in West Antarctica. Although the glacial-interglacial increases result in high correlation and moderate sensitivity for the full record, the relationship shows considerable variability through time with high correlation and high sensitivity for the 0-8 ka period but no correlation for the 8-15 ka period. This contrasts with a general circulation model simulation which shows homogeneous sensitivities between temperature and accumulation across the entire time period. These results suggest that variations in atmospheric circulation are an important driver of Antarctic accumulation but they are not adequately captured in model simulations. Model-based projections of future Antarctic accumulation, and its impact on sea level, should be treated with caution.

  7. Evidence for a weakening relationship between interannual temperature variability and northern vegetation activity

    NASA Astrophysics Data System (ADS)

    Piao, Shilong; Nan, Huijuan; Huntingford, Chris; Ciais, Philippe; Friedlingstein, Pierre; Sitch, Stephen; Peng, Shushi; Ahlström, Anders; Canadell, Josep G.; Cong, Nan; Levis, Sam; Levy, Peter E.; Liu, Lingli; Lomas, Mark R.; Mao, Jiafu; Myneni, Ranga B.; Peylin, Philippe; Poulter, Ben; Shi, Xiaoying; Yin, Guodong; Viovy, Nicolas; Wang, Tao; Wang, Xuhui; Zaehle, Soenke; Zeng, Ning; Zeng, Zhenzhong; Chen, Anping

    2014-10-01

    Satellite-derived Normalized Difference Vegetation Index (NDVI), a proxy of vegetation productivity, is known to be correlated with temperature in northern ecosystems. This relationship, however, may change over time following alternations in other environmental factors. Here we show that above 30°N, the strength of the relationship between the interannual variability of growing season NDVI and temperature (partial correlation coefficient RNDVI-GT) declined substantially between 1982 and 2011. This decrease in RNDVI-GT is mainly observed in temperate and arctic ecosystems, and is also partly reproduced by process-based ecosystem model results. In the temperate ecosystem, the decrease in RNDVI-GT coincides with an increase in drought. In the arctic ecosystem, it may be related to a nonlinear response of photosynthesis to temperature, increase of hot extreme days and shrub expansion over grass-dominated tundra. Our results caution the use of results from interannual time scales to constrain the decadal response of plants to ongoing warming.

  8. Evidence for a weakening relationship between interannual temperature variability and northern vegetation activity.

    PubMed

    Piao, Shilong; Nan, Huijuan; Huntingford, Chris; Ciais, Philippe; Friedlingstein, Pierre; Sitch, Stephen; Peng, Shushi; Ahlström, Anders; Canadell, Josep G; Cong, Nan; Levis, Sam; Levy, Peter E; Liu, Lingli; Lomas, Mark R; Mao, Jiafu; Myneni, Ranga B; Peylin, Philippe; Poulter, Ben; Shi, Xiaoying; Yin, Guodong; Viovy, Nicolas; Wang, Tao; Wang, Xuhui; Zaehle, Soenke; Zeng, Ning; Zeng, Zhenzhong; Chen, Anping

    2014-01-01

    Satellite-derived Normalized Difference Vegetation Index (NDVI), a proxy of vegetation productivity, is known to be correlated with temperature in northern ecosystems. This relationship, however, may change over time following alternations in other environmental factors. Here we show that above 30°N, the strength of the relationship between the interannual variability of growing season NDVI and temperature (partial correlation coefficient RNDVI-GT) declined substantially between 1982 and 2011. This decrease in RNDVI-GT is mainly observed in temperate and arctic ecosystems, and is also partly reproduced by process-based ecosystem model results. In the temperate ecosystem, the decrease in RNDVI-GT coincides with an increase in drought. In the arctic ecosystem, it may be related to a nonlinear response of photosynthesis to temperature, increase of hot extreme days and shrub expansion over grass-dominated tundra. Our results caution the use of results from interannual time scales to constrain the decadal response of plants to ongoing warming. PMID:25318638

  9. Physical Mechanism of the Surface Air Temperature Variability in Korea and Near Seven-Day Oscillations

    NASA Astrophysics Data System (ADS)

    Kim, K.; Roh, J.

    2009-12-01

    The first three principal modes of wintertime surface temperature variability in Seoul, Korea (126.59°E, 37.33°N) are extracted from the 1979-2008 observed records via cyclostationary EOF (CSEOF) analysis. Then, physically consistent patterns of several key physical variables over East Asia (97.5°-152.5°E×22.5°-72.5°N) are derived from the NCEP/NCAR reanalysis data in order to understand the physical and dynamical mechanisms of the derived CSEOF modes. The first mode represents the seasonal cycle, the principle physical mechanism of which is associated with the continent/ocean sea level pressure contrast. The second mode mainly describes overall wintertime warming or cooling. The third mode depicts subseasonal fluctuations of surface temperature. Sea level pressure anomalies to the west of Korea (eastern China) and those with an opposite sign to the east of Korea (Japan) are a major physical mechanism both for the second mode and the third mode. These sea level pressure anomalies with opposite signs alter the amount of warm air to the south of Korea, which, in turn, varies the surface temperature in Korea. The PC time series of the seasonal cycle is significantly correlated with the East Asian winter monsoon index and exhibits a conspicuous downward trend. The PC time series of the second mode exhibits a positive trend. These trends imply that the wintertime surface temperature in Korea has increased and the seasonal cycle has weakened gradually in the past 30 years; the sign of greenhouse warming is clear in both PC time series. The seasonal cycle has decreased since the impact of warming as reflected in the sea level pressure change is much stronger over the continent than over the ocean; greater sea level pressure decrease over the continent than over the ocean reduces the wintertime sea level pressure contrast between the continent and the ocean thereby weakening the seasonal cycle. The ~7-day oscillations, also called the three-cold-day/four-warm-day events, are clearly seen in the second and the third CSEOF modes. The ~7-day oscillations are a major component of high-frequency variability in much of the analysis domain and are a manifestation of Rossby waves. Rossby waves aloft result in the concerted variation of physical variables in the atmospheric column; the nature of this response is of nearly barotropic and is clearly felt at the surface. Due to the stronger mean zonal wind, the disturbances by Rossby waves propagate eastward at ~8-12 m/sec; the passing of Rossby waves with alternating signs produces the ~7-day temperature oscillations in Korea. Thus, it is the speed of eastward propagation of Rossby waves not the phase speed of Rossby waves that determines the period of oscillations.

  10. NOM degradation during river infiltration: effects of the climate variables temperature and discharge.

    PubMed

    Diem, Samuel; Rudolf von Rohr, Matthias; Hering, Janet G; Kohler, Hans-Peter E; Schirmer, Mario; von Gunten, Urs

    2013-11-01

    Most peri-alpine shallow aquifers fed by rivers are oxic and the drinking water derived by riverbank filtration is generally of excellent quality. However, observations during past heat waves suggest that water quality may be affected by climate change due to effects on redox processes such as aerobic respiration, denitrification, reductive dissolution of manganese(III/IV)- and iron(III)(hydr)oxides that occur during river infiltration. To assess the dependence of these redox processes on the climate-related variables temperature and discharge, we performed periodic and targeted (summer and winter) field sampling campaigns at the Thur River, Switzerland, and laboratory column experiments simulating the field conditions. Typical summer and winter field conditions could be successfully simulated by the column experiments. Dissolved organic matter (DOM) was found not to be a major electron donor for aerobic respiration in summer and the DOM consumption did not reveal a significant correlation with temperature and discharge. It is hypothesized that under summer conditions, organic matter associated with the aquifer material (particulate organic matter, POM) is responsible for most of the consumption of dissolved oxygen (DO), which was the most important electron acceptor in both the field and the column system. For typical summer conditions at temperatures >20 °C, complete depletion of DO was observed in the column system and in a piezometer located only a few metres from the river. Both in the field system and the column experiments, nitrate acted as a redox buffer preventing the release of manganese(II) and iron(II). For periodic field observations over five years, DO consumption showed a pronounced temperature dependence (correlation coefficient r = 0.74) and therefore a seasonal pattern, which seemed to be mostly explained by the temperature dependence of the calculated POM consumption (r = 0.7). The river discharge was found to be highly and positively correlated with DO consumption (r = 0.85), suggesting an enhanced POM input during flood events. This high correlation could only be observed for the low-temperature range (T < 15 °C). For temperatures >15 °C, DO consumption was already high (almost complete) and the impact of discharge could not be resolved. Based on our results, we estimate the risk for similar river-infiltration systems to release manganese(II) and iron(II) to be low during future average summer conditions. However, long-lasting heat waves might lead to a consumption of the nitrate buffer, inducing a mobilization of manganese and iron. PMID:24064550

  11. 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.

  12. Sea surface temperature variability off southern Brazil and Uruguay as revealed from historical data since 1854

    NASA Astrophysics Data System (ADS)

    Zavialov, Peter O.; Wainer, Ilana; Absy, JoãO. M.

    1999-09-01

    About 300,000 quality-controlled local reports from ships of opportunity were complemented with the data extracted from global data records to compile monthly series of sea surface temperature (SST) for the period 1854 to 1994 on a grid 1° × 1° in latitude and longitude. These historical data are used to investigate the variability off the coast of southern Brazil and Uruguay in a broad range of temporal scales from seasonal to secular. With respect to behavior at these scales, three distinct areas can be identified in the study region. The first one, located over the shelf and controlled by winter invasions of subantarctic water along with Rio de la Plata and Patos-Mirim discharges, is characterized by large annual range of SST (7° to over 10°C), energetic mean square variability (from 1.4 to 2.2°C2, after removal of seasonal signal), and an extremely high secular trend toward warming (1.2 to 1.6°C per 100 years), especially in the proximity of the estuaries. The second one, an area of the Brazil Current influence, exhibits smaller annual range (5° to 7°C) and mean square variability (1 to 1.4°C2). The secular trend is from 1° to 1.2°C per 100 years, smaller than observed in the shelf, but still high compared to the global average. The third area, which encompasses the eastern deep ocean part of the region away from the influence of either major currents or coastal discharges, exhibits less energetic variability at all examined scales, as compared to the rest of the region. Everywhere in the region, 50 to 80% of interannual variability is associated with periods smaller than 10 years; however, compared to the rest of the region, the shelf zone is characterized by a relatively large contribution from decadal and interdecadal scales. In austral winter a thermal front forms in the study region, separating warm tropical water associated with the Brazil Current and cold subantarctic water flowing northward on the shelf with an admixture of coastal freshwater discharges. The position of this frontal zone is subject to strong year-to-year changes. More than a half of the energy of these migrations resides at periods smaller than 10 years where the spectrum is fairly white. In the interdecadal part of the spectrum, at least three significant individual peaks can be identified, corresponding to periods of 47±2, 27±1, and 18 years.

  13. Patterns Of Intraseasonal Temperature Variability And Their Relations With Enhanced Local Predictability

    NASA Astrophysics Data System (ADS)

    Naumann, G.; Vargas, W. M.

    2009-12-01

    The knowledge of patterns that represent variability at the intraseasonal scale is one of the keys to understand the processes involved in this time scale. Current weather predictions indicate that predictability is relatively good for three weeks (Simmons and Hollingsworth 2002), however some spatial and temporal structures can be predicted beyond this period. Detecting these structures is difficult because unpredictable patterns that govern the physical effects exist superimposed on the predictable ones (Del Sole and Tippet, 2007). However, some persistent components can be predictable beyond three weeks and can also explain the variability of the monthly means, even if these processes explain little of the daily variability (Shukla 1981a). In this light, Lorenz (1969) and Shukla (1981b) explain that large-scale dynamical processes tend to be more persistent and hence more predictable than small-scale processes. To detect the thermal structures that produce persistent phenomena a wavelet spectral analysis was performed over the daily maximum and minimum temperatures. The stations or reference series used in the analysis must have long records of high quality measurements, and must represent different or specific climatic regions of southern South America. This analysis aims to detect the main spectral features at the intraseasonal scale, where non-linear effects tend to produce quasi-periodicities over the daily temperature in the region. A major feature is the 30-60 days quasi-periodicities in daily temperatures that seem to appear over the entire region. In general these periodicities can persist from 30 to 100 days. This means that the transitions between cold and hot events (a 30-60 days pattern) can persist over an entire season. Moreover, the occurrence of these periodicities has a markedly seasonal behavior with a maximum during winter which is highly related with the extreme cold air outbreaks. An interannual analysis shows that the intraseasonal periodicities have 30 to 50 % probability of occurrence. Furthermore, we can observe that they tend to appear usually at 1-2 year intervals, less frequently at 4-12 year intervals and rarely at 20-year intervals. This behavior indicates the existence of biennial and triennial processes with specific circulation patterns that generate persistent events, as well as other processes in which different effects seem to prevail. In order to detect the intraseasonal patterns of the thermal structure, both a principal components analysis (PCA) and a cluster analysis were performed. These methodologies show similar results. This pattern shows regional coherence, with a similar pattern in the whole region. The oscillation pattern is characterized by an increased intraseasonal signal in winter for the maximum and minimum temperatures. The analysis of the two variables shows that the beginning of this signal is associated with a warm air outbreak followed 30 days later by an intense cold air outbreak. Following this, a hot wave is observed during the month of July and approximately 30 days later another strong cold outbreak is detected. Before and after this period the intraseasonal signal is rather inconsistent with negligible amplitudes.

  14. Patterns of intraseasonal temperature variability and their relations with enhanced local predictability

    NASA Astrophysics Data System (ADS)

    Naumann, Gustavo; Vargas, Walter

    2010-05-01

    The knowledge of patterns that represent variability at the intraseasonal scale is one of the keys to understand the processes involved in this time scale. Current weather predictions indicate that predictability is relatively good for three weeks (Simmons and Hollingsworth 2002), however some spatial and temporal structures can be predicted beyond this period. Detecting these structures is difficult because unpredictable patterns that govern the physical effects exist superimposed on the predictable ones (Del Sole and Tippet, 2007). However, some persistent components can be predictable beyond three weeks and can also explain the variability of the monthly means, even if these processes explain little of the daily variability (Shukla 1981a). In this light, Lorenz (1969) and Shukla (1981b) explain that large-scale dynamical processes tend to be more persistent and hence more predictable than small-scale processes. To detect the thermal structures that produce persistent phenomena a wavelet spectral analysis was performed over the daily maximum and minimum temperatures. The stations or reference series used in the analysis must have long records of high quality measurements, and must represent different or specific climatic regions of southern South America. This analysis aims to detect the main spectral features at the intraseasonal scale, where non-linear effects tend to produce quasi-periodicities over the daily temperature in the region. A major feature is the 30-60 days quasi-periodicities in daily temperatures that seem to appear over the entire region. In general these periodicities can persist from 30 to 100 days. This means that the transitions between cold and hot events (a 30-60 days pattern) can persist over an entire season. Moreover, the occurrence of these periodicities has a markedly seasonal behavior with a maximum during winter which is highly related with the extreme cold air outbreaks. An interannual analysis shows that the intraseasonal periodicities have 30 to 50 % probability of occurrence. Furthermore, we can observe that they tend to appear usually at 1-2 year intervals, less frequently at 4-12 year intervals and rarely at 20-year intervals. This behavior indicates the existence of biennial and triennial processes with specific circulation patterns that generate persistent events, as well as other processes in which different effects seem to prevail. In order to detect the intraseasonal patterns of the thermal structure, both a principal components analysis (PCA) and a cluster analysis were performed. These methodologies show similar results. This pattern shows regional coherence, with a similar pattern in the whole region. The oscillation pattern is characterized by an increased intraseasonal signal in winter for the maximum and minimum temperatures. The analysis of the two variables shows that the beginning of this signal is associated with a warm air outbreak followed 30 days later by an intense cold air outbreak. Following this, a hot wave is observed during the month of July and approximately 30 days later another strong cold outbreak is detected. Before and after this period the intraseasonal signal is rather inconsistent with negligible amplitudes.

  15. 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.

  16. Direct Measures of Time-Dependent Diameters and Temperatures of Mira Variables

    NASA Astrophysics Data System (ADS)

    Ruiz-Velasco, Alma Emilia; van Belle, Gerard; Creech-Eakman, Michelle J.

    2016-01-01

    We examine archival data of the Palomar Testbed Inteferometer (PTI) covering a sample of 85 Mira variable stars. The sample contains the three most common types: 65 oxygen-rich (M-type), 11 carbon-rich (C-type) and 9 of the intermediary S-type; periods ranging from 150 to 600 days. The PTI database spans over nine years of data; up to 80 epochs for individual stars, spanning multiple pulsation cycles per star. These interferometric angular sizes, along with ancillary measures of distance and bolometric flux, can be used to determine linear size and effective temperature, respectively. Additionally, the PTI data can be divided into narrowband data across the K-band (2.0-2.4 μ m), allowing separate analysis of spatially resolved continuum and prominent molecular-bandhead regions of these stars, which typically pulsate out of phase. Preliminary results show average sizes changes of 40% for the stellar radii and 44 % for the molecular envelopes.

  17. Variable Temperature Infrared Spectroscopy Investigation of Benzoic Acid Interactions with Montmorillonite Clay Interlayer Water.

    PubMed

    Nickels, Tara M; Ingram, Audrey L; Maraoulaite, Dalia K; White, Robert L

    2015-07-01

    Molecular interactions between benzoic acid and cations and water contained in montmorillonite clay interlayer spaces are characterized by using variable temperature diffuse reflection infrared Fourier transform spectroscopy (VT-DRIFTS). Using sample perturbation and difference spectroscopy, infrared spectral changes resulting from removal of interlayer water and associated changes in local benzoic acid environments are identified. Difference spectra features can be correlated with changes in specific molecular vibrations that are characteristic of benzoic acid molecular orientation. Results suggest that the carboxylic acid functionality of benzoic acid interacts with interlayer cations through a bridging water molecule and that this interaction is affected by the nature of the cation present in the clay interlayer space. PMID:26037917

  18. Spatial variability of maximum and minimum monthly temperature in Spain during 1981-2010 evaluated by correlation decay distance (CDD)

    NASA Astrophysics Data System (ADS)

    Pena-Angulo, D.; Cortesi, N.; Brunetti, M.; González-Hidalgo, J. C.

    2015-10-01

    The spatial variability of monthly diurnal and nocturnal mean values of temperature in Spain has been analysed to evaluate the optimal threshold distance between neighbouring stations that make a meteorological network (in terms of stations' density) well representative of the conterminous land of Spain. To this end, the correlation decay distance has been calculated using the highest quality monthly available temperature series (1981-2010) from AEMet (National Spanish Meteorological Agency). In the conterminous land of Spain, the distance at which couples of stations have a common variance above the selected threshold (50 %, r Pearson ˜0.70) for both maximum and minimum temperature on average does not exceed 400 km, with relevant spatial and temporal differences, and in extended areas of Spain, this value is lower than 200 km. The spatial variability for minimum temperature is higher than for maximum, except in cold months when the reverse is true. Spatially, highest values are located in both diurnal and nocturnal temperatures to the southeastern coastland and lower spatial variability is found to the inland areas, and thus the spatial variability shows a clear coastland-to-inland gradient at annual and monthly scale. Monthly analyses show that the highest spatial variability in maximum and minimum temperatures occur in July and August, when radiation is maximum, and in lowland areas, (<200 m o.s.l.), which coincide with the mostly transformed landscapes, particularly by irrigation and urbanization. These results highlight local factors could play a major role on spatial variability of temperature. Being maximum and minimum temperature interstation correlation values highly variable in Spanish land, an average of threshold distance of about 200 km as a limit value for a well representative network should be recommended for climate analyses,.

  19. Influence of temperature and precipitation variability on near-term snow trends

    NASA Astrophysics Data System (ADS)

    Mankin, Justin S.; Diffenbaugh, Noah S.

    2015-08-01

    Snow is a vital resource for a host of natural and human systems. Global warming is projected to drive widespread decreases in snow accumulation by the end of the century, potentially affecting water, food, and energy supplies, seasonal heat extremes, and wildfire risk. However, over the next few decades, when the planning and implementation of current adaptation responses are most relevant, the snow response is more uncertain, largely because of uncertainty in regional and local precipitation trends. We use a large (40-member) single-model ensemble climate model experiment to examine the influence of precipitation variability on the direction and magnitude of near-term Northern Hemisphere snow trends. We find that near-term uncertainty in the sign of regional precipitation change does not cascade into uncertainty in the sign of regional snow accumulation change. Rather, temperature increases drive statistically robust consistency in the sign of future near-term snow accumulation trends, with all regions exhibiting reductions in the fraction of precipitation falling as snow, along with mean decreases in late-season snow accumulation. However, internal variability does create uncertainty in the magnitude of hemispheric and regional snow changes, including uncertainty as large as 33 % of the baseline mean. In addition, within the 40-member ensemble, many mid-latitude grid points exhibit at least one realization with a statistically significant positive trend in net snow accumulation, and at least one realization with a statistically significant negative trend. These results suggest that the direction of near-term snow accumulation change is robust at the regional scale, but that internal variability can influence the magnitude and direction of snow accumulation changes at the local scale, even in areas that exhibit a high signal-to-noise ratio.

  20. 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.

    2015-10-01

    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.

  1. Interannual to decadal temperature variability in the north-west Atlantic: Observations from the MV Oleander XBT line

    NASA Astrophysics Data System (ADS)

    Forsyth, J. S. T.; Andres, M.; Gawarkiwicz, G.

    2014-12-01

    Despite convincing evidence of deep ocean warming, temperature changes over the shelves have proven difficult to quantify as most long-term records lack the spatial and temporal resolution needed to resolve shelf variability. XBT data have been collected for 37 years along a repeat track from New Jersey to Bermuda from the MV Oleander providing the resolution necessary for shelf analysis. The XBT temperature data on the shelf (onshore of the 80 m isobath) were binned with 10 km horizontal and 5 m vertical resolution to produce monthly and annually averaged temperature sections. A climatology produced from the binned data identifies key seasonal temperature features consistent with previous climatologies, showing the utility of the XBT data. Annual spatially-averaged shelf temperatures have trended upwards since the beginning of the record in 1977 (0.025 C/yr), with recent trends (i.e., since 2002, 0.10 C/yr) substantially larger than the overall 37- year trend. Comparison of composite sections for the most anomalous years suggests that the interannual variability in the spatially-averaged temperatures is most heavily influenced by temperature anomalies near the shelf break. The spatially-averaged temperature anomalies are not correlated with annually-averaged coastal sea level anomalies from tide gauges at zero lag, which suggest that interannual variability in coastal sea level is not due to thermo steric effects. However, a strong positive correlation is found between 2-year lagged temperature anomalies and coastal sea level anomalies. This relationship is most pronounced for the shelf break temperature anomalies, with the strongest 2-year lag correlations found in winter and spring. Connections between the observed interannual to decadal temperature variability on the shelf and variability in the AMOC are being investigated in an ongoing effort to better understand open-ocean/shelf interactions in the Northwest Atlantic.

  2. Trends and variability of daily temperature extremes during 1960-2012 in the Yangtze River Basin, China

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The variability of temperature extremes has been the focus of attention during the past few decades, and may exert a great influence on the global hydrologic cycle and energy balance through thermal forcing. Based on daily minimum and maximum temperature observed by the China Meteorological Administ...

  3. The role of Atlantic Multi-decadal Oscillation in the global mean temperature variability

    NASA Astrophysics Data System (ADS)

    Chylek, Petr; Klett, James D.; Dubey, Manvendra K.; Hengartner, Nicolas

    2016-02-01

    The global mean 1900-2015 warming simulated by 42 Coupled Models Inter-comparison Project, phase 5 (CMIP5) climate models varies between 0.58 and 1.70 °C. The observed warming according to the NASA GISS temperature analysis is 0.95 °C with a 1200 km smoothing radius, or 0.86 °C with a 250 km smoothing radius. The projection of the future 2015-2100 global warming under a moderate increase of anthropogenic radiative forcing (RCP4.5 scenario) by individual models is between 0.7 and 2.3 °C. The CMIP5 climate models agree that the future climate will be warmer; however, there is little consensus as to how large the warming will be (reflected by an uncertainty of over a factor of three). A parsimonious statistical regression model with just three explanatory variables [anthropogenic radiative forcing due to greenhouse gases and aerosols (GHGA), solar variability, and the Atlantic Multi-decadal Oscillation (AMO) index] accounts for over 95 % of the observed 1900-2015 temperature variance. This statistical regression model reproduces very accurately the past warming (0.96 °C compared to the observed 0.95 °C) and projects the future 2015-2100 warming to be around 0.95 °C (with the IPCC 2013 suggested RCP4.5 radiative forcing and an assumed cyclic AMO behavior). The AMO contribution to the 1970-2005 warming was between 0.13 and 0.20 °C (depending on which AMO index is used) compared to the GHGA contribution of 0.49-0.58 °C. During the twenty-first century AMO cycle the AMO contribution is projected to remain the same (0.13-0.20 °C), while the GHGA contribution is expected to decrease to 0.21-0.25 °C due to the levelling off of the GHGA radiative forcing that is assumed according to the RCP4.5 scenario. Thus the anthropogenic contribution and natural variability are expected to contribute about equally to the anticipated global warming during the second half of the twenty-first century for the RCP4.5 trajectory.

  4. 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.

  5. 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.

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

    SciTech Connect

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

    2015-05-07

    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.

  7. 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.

  8. 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.

  9. Decadal variability in PMCs and implications for changing temperature and water vapor in the upper mesosphere

    NASA Astrophysics Data System (ADS)

    Hervig, Mark E.; Berger, Uwe; Siskind, David E.

    2016-03-01

    Observations of polar mesospheric clouds (PMC) from the solar backscatter ultraviolet (SBUV) satellite instruments are used to characterize variability and trends from 1979 to 2014. The SBUV PMC record indicates decadal oscillations during the 1980s and 1990s, which are expected to result from the 11 year solar cycle. This oscillation is absent in the recent decade, however, and we speculate that solar cycle effects at PMC altitudes during the 1980s and 1990s may have been fortuitously amplified by stratospheric warming due to volcanic eruptions which occurred near solar maximum. SBUV trend results are compared with temperature, water vapor, and PMCs from the Mesospheric Ice Microphysics and Transport (MIMAS) model. Both SBUV and the model indicate positive trends in PMC vertically integrated water content (IWC), which increase toward higher latitudes. Using analysis of Solar Occultation for Ice Experiment (SOFIE) observations, the SBUV IWC trends are expressed in terms of the underlying changes in temperature and water vapor in the upper mesosphere. SBUV indicates cooling trends that increase toward higher latitudes (-0.5 ± 0.2 K decade-1 at 77°N), consistent with the MIMAS model and scant observations. SBUV indicates increasing water vapor in the Northern Hemisphere upper mesosphere (0.07 ± 0.03 ppmv decade-1 at 77°N, insignificant in the Southern Hemisphere), with values that are consistent with MIMAS but less than expected due to increasing methane.

  10. 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.

  11. 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.

  12. Millennial-scale temperature variability during Marine Isotope Stages 19 and 31 in the continental Arctic

    NASA Astrophysics Data System (ADS)

    de Wet, G.; Castañeda, I. S.; Brigham-Grette, J.; Salacup, J. M.; Keisling, B. A.; Habicht, M. H.

    2014-12-01

    In light of predicted climate change, high-resolution paleoclimate records are essential to accurately contextualize future warming. The Arctic region in particular is currently lacking terrestrial paleoclimate reconstructions that extend beyond the last glacial period. A sediment core from Lake El'gygytgyn (Russia) provides a continuous record of Arctic climate spanning the past 3.6 Ma. Here we utilize molecular organic proxies to create millennial-scale paleotemperature reconstructions through Marine Isotope Stages (MIS) 19 and 31, two interglacial periods considered to be good analogs for the current interglacial and future climate change, respectively. MIS 31 has been previously identified a "super interglacial" period at Lake El'gygytgyn whereas MIS 19 provides an analog for the current MIS 1 interglacial, without anthropogenic influences, due to similar orbital forcing. Our paleotemperature reconstructions, based on the branched glycerol dialkyl glycerol tetraether (brGDGT) paleothermometer, demonstrate that Lake El'gygytgyn sediments capture glacial-interglacial climate variability noted in global climate records (Figure 1) and suggests close ties to Antarctic climate. We find that MIS 31 was the warmest interglacial period of the past ~ 1 Ma, in agreement with pollen-derived temperature estimates. Our cm-scale brGDGT temperature reconstruction, with an average time step of <500 years, to the best of our knowledge provides the highest resolution Arctic paleoclimate record of this "super interglacial" and reveals variability hitherto unobserved by lower resolution marine records. Our results are placed in context of paleotemperature reconstructions over the period of MIS 19-35. Remarkably, multiple proxies display a number of abrupt and short-lived temperature fluctuations of ca. 3-5°C occurring within MIS 19 and 31, as well as within other previous interglacials at Lake El'gygytgyn. We examine our results in the context of other biomarker records, existing paleolimnological data, and modeling studies of Lake El'gygytgyn, as well as other high latitude records, to better understand the nature of interglacial climate during these two important intervals in the Arctic.

  13. 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 30N of D26 is homogenous along 10-15N. Monthly mean D26 along 10-15N, 125-145E 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 (<15N) where background climatological condition is warm all throughout the year with deep D26 and BNorth (>15N), 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 1C. 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 7C 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 4C in BSouth associated with deeper D26 of >= 100m allowing only warm water (Temp>26) to be brought to the surface.

  14. Observed and SST-forced multidecadal variability in global land surface air temperature

    NASA Astrophysics Data System (ADS)

    Gao, L. H.; Yan, Z. W.; Quan, X. W.

    2015-01-01

    The characteristics of multidecadal variability (MDV) in global land surface air temperature (SAT) are analyzed based on observations. The role of sea surface temperature (SST) variations in generating MDV in land SAT is assessed using atmospheric general circulation model simulations forced by observed SST. MDV in land SAT exhibits regional differences, with amplitude larger than 0.3 °C mainly over North America, East Asia, Northern Eurasia, Northern Africa and Greenland for the study period of 1902-2004. MDV can account for more than 30 % of long-term temperature variation during the last century in most regions, especially more than 50 % in parts of the above-mentioned regions. The SST-forced simulations reproduce the observed feature of zonal mean MDV in land SAT, though with weaker amplitude especially at the northern high-latitudes. Two types of MDV in land SAT, one of 60-year-timescale, mainly observed in the northern mid-high-latitude lands, and another of 20-30-year-timescale, mainly observed in the low-latitude lands, are also well reproduced. The SST-forced MDV accounts for more than 40 % amplitude of observed MDV in most regions. Except for some sporadically distributed regions in central Eurasia, South America and Western Australia, the SST-forced multidecadal variations are well in-phase with observations. The Atlantic Multidecadal Oscillation and Pacific Decadal Oscillation signals are found dominant in MDV of both the observed and SST-forced land SAT, suggesting important roles of these oceanic oscillations in generating MDV in global land SAT.

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

  16. 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.

  17. Apparatus and Method for Measuring Air Temperature Ahead of an Aircraft for Controlling a Variable Inlet/Engine Assembly

    NASA Technical Reports Server (NTRS)

    Gary, Bruce L. (Inventor)

    2001-01-01

    The apparatus and method employ remote sensing to measure the air temperature a sufficient distance ahead of the aircraft to allow time for a variable inlet/engine assembly to be reconfigured in response to the measured temperature, to avoid inlet unstart and/or engine compressor stall. In one embodiment, the apparatus of the invention has a remote sensor for measuring at least one air temperature ahead of the vehicle and an inlet control system for varying the inlet. The remote sensor determines a change in temperature value using at least one temperature measurement and prior temperature measurements corresponding to the location of the aircraft. The control system uses the change in air temperature value to vary the inlet configuration to maintain the position of the shock wave during the arrival of the measured air in the inlet. In one embodiment, the method of the invention includes measuring at least one air temperature ahead of the vehicle, determining an air temperature at the vehicle from prior air temperature measurements, determining a change in temperature value using the air temperature at the vehicle and the at least one air temperature measurement ahead of the vehicle, and using the change in temperature value to-reposition the airflow inlet, to cause the shock wave to maintain substantially the same position within the inlet as the airflow temperature changes within the inlet.

  18. Quantifying the processes controlling intraseasonal mixed-layer temperature variability in the tropical Indian Ocean

    NASA Astrophysics Data System (ADS)

    Halkides, D. J.; Waliser, Duane E.; Lee, Tong; Menemenlis, Dimitris; Guan, Bin

    2015-02-01

    Spatial and temporal variation of processes that determine ocean mixed-layer (ML) temperature (MLT) variability on the timescale of the Madden-Julian Oscillation (MJO) in the Tropical Indian Ocean (TIO) are examined in a heat-conserving ocean state estimate for years 1993-2011. We introduce a new metric for representing spatial variability of the relative importance of processes. In general, horizontal advection is most important at the Equator. Subsurface processes and surface heat flux are more important away from the Equator, with surface heat flux being the more dominant factor. Analyses at key sites are discussed in the context of local dynamics and literature. At 0°, 80.5°E, for MLT events > 2 standard deviations, ocean dynamics account for more than two thirds of the net tendency during cooling and warming phases. Zonal advection alone accounts for ˜40% of the net tendency. Moderate events (1-2 standard deviations) show more differences between events, and some are dominated by surface heat flux. At 8°S, 67°E in the Seychelles-Chagos Thermocline Ridge (SCTR) area, surface heat flux accounts for ˜70% of the tendency during strong cooling and warming phases; subsurface processes linked to ML depth (MLD) deepening (shoaling) during cooling (warming) account for ˜30%. MLT is more sensitive to subsurface processes in the SCTR, due to the thin MLD, thin barrier layer and raised thermocline. Results for 8°S, 67°E support assertions by Vialard et al. (2008) not previously confirmed due to measurement error that prevented budget closure and the small number of events studied. The roles of MLD, barrier layer thickness, and thermocline depth on different timescales are examined.

  19. Effects of modeled tropical sea surface temperature variability on coral reef bleaching predictions

    NASA Astrophysics Data System (ADS)

    van Hooidonk, R.; Huber, M.

    2012-03-01

    Future widespread coral bleaching and subsequent mortality has been projected using sea surface temperature (SST) data derived from global, coupled ocean-atmosphere general circulation models (GCMs). While these models possess fidelity in reproducing many aspects of climate, they vary in their ability to correctly capture such parameters as the tropical ocean seasonal cycle and El Nio Southern Oscillation (ENSO) variability. Such weaknesses most likely reduce the accuracy of predicting coral bleaching, but little attention has been paid to the important issue of understanding potential errors and biases, the interaction of these biases with trends, and their propagation in predictions. To analyze the relative importance of various types of model errors and biases in predicting coral bleaching, various intra- and inter-annual frequency bands of observed SSTs were replaced with those frequencies from 24 GCMs 20th century simulations included in the Intergovernmental Panel on Climate Change (IPCC) 4th assessment report. Subsequent thermal stress was calculated and predictions of bleaching were made. These predictions were compared with observations of coral bleaching in the period 1982-2007 to calculate accuracy using an objective measure of forecast quality, the Peirce skill score (PSS). Major findings are that: (1) predictions are most sensitive to the seasonal cycle and inter-annual variability in the ENSO 24-60 months frequency band and (2) because models tend to understate the seasonal cycle at reef locations, they systematically underestimate future bleaching. The methodology we describe can be used to improve the accuracy of bleaching predictions by characterizing the errors and uncertainties involved in the predictions.

  20. Inferring land surface parameters from the diurnal variability of microwave and infrared temperatures

    NASA Astrophysics Data System (ADS)

    Norouzi, Hamidreza; Temimi, Marouane; AghaKouchak, Amir; Azarderakhsh, Marzieh; Khanbilvardi, Reza; Shields, Gerarda; Tesfagiorgis, Kibrewossen

    This study investigates the properties of the diurnal cycle of microwave brightness temperatures (TB), namely the phase and the amplitude, and their variability in time and space over the globe to infer information on key land surface parameters like changes in soil texture spatial distribution, soil moisture conditions, and vegetation density. The phase corresponds to the lag between Land Surface Temperature (LST) and TB diurnal cycles. The amplitude is determined as the difference between the maximum and the minimum of TB diurnal cycle. The diurnal cycle of TB was constructed using observations from the Advanced Microwave Scanning Radiometer-Earth Observing System (AMSR-E) and the Special Sensor Microwave/Imager (SSM/I). The latter offer a series of sensors, namely, F13, F14, and F15 that were used in this study for a higher temporal coverage and more accurate diurnal cycle determination. LST estimates, which are available every 3 h from the International Satellite Cloud Climatology Project (ISCCP) database were used to build the LST diurnal cycle. ISCCP LST data is an infrared-based temperature with almost no penetration and is the representative of top skin temperature. The analyses of the diurnal cycles showed that the diurnal amplitude of TB decreases as the vegetation density increases, especially in the case of low frequencies which penetrate deeper into the canopy which makes them more sensitive to changes in vegetation density. The interannual variations of TB diurnal amplitudes were also in agreement with the seasonality of the vegetation cover. Over desert and rain forest regions where surface conditions do not vary significantly throughout the year, the changes in diurnal amplitudes were the lowest. A relationship between phase and amplitude values was established. It was found that the amplitude of TB diurnal cycle decreases when the phase lag increases. The spatial distribution of the determined diurnal properties, namely, phase and amplitude of TB, showed an agreement with lithology maps in desert areas. Lower TB amplitudes were observed over regions with loose siliceous rocks. Phase lag values between 1.5 and 3 h corresponded to 83% of the class "loose siliceous rocks" in the Sahara Desert, which corroborates the potential of using the diurnal properties of TB as an indicator of land surface parameters.

  1. 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.

  2. Interannual variability of the midsummer drought in Central America and the connection with sea surface temperatures

    NASA Astrophysics Data System (ADS)

    Maldonado, Tito; Rutgersson, Anna; Alfaro, Eric; Amador, Jorge; Claremar, Björn

    2016-04-01

    The midsummer drought (MSD) in Central America is characterised in order to create annual indexes representing the timing of its phases (start, minimum and end), and other features relevant for MSD forecasting such as the intensity and the magnitude. The MSD intensity is defined as the minimum rainfall detected during the MSD, meanwhile the magnitude is the total precipitation divided by the total days between the start and end of the MSD. It is shown that the MSD extends along the Pacific coast, however, a similar MSD structure was detected also in two stations in the Caribbean side of Central America, located in Nicaragua. The MSD intensity and magnitude show a negative relationship with Niño 3.4 and a positive relationship with the Caribbean low-level jet (CLLJ) index, however for the Caribbean stations the results were not statistically significant, which is indicating that other processes might be modulating the precipitation during the MSD over the Caribbean coast. On the other hand, the temporal variables (start, minimum and end) show low and no significant correlations with the same indexes.The results from canonical correlation analysis (CCA) show good performance to study the MSD intensity and magnitude, however, for the temporal indexes the performance is not satisfactory due to the low skill to predict the MSD phases. Moreover, we find that CCA shows potential predictability of the MSD intensity and magnitude using sea surface temperatures (SST) with leading times of up to 3 months. Using CCA as diagnostic tool it is found that during June, an SST dipole pattern upon the neighbouring waters to Central America is the main variability mode controlling the inter-annual variability of the MSD features. However, there is also evidence that the regional waters are playing an important role in the annual modulation of the MSD features. The waters in the PDO vicinity might be also controlling the rainfall during the MSD, however, exerting an opposite effect at the north and south regions of Central America.

  3. Adriatic Sea surface temperature and ocean colour variability during the MFSPP

    NASA Astrophysics Data System (ADS)

    Böhm, E.; Banzon, V.; D'Acunzo, E.; D'Ortenzio, F.; Santoleri, R.

    2003-01-01

    Two years and six months of night-time Advanced Very High Resolution Radiometer (AVHRR) sea surface temperature (SST) and daytime Sea viewing Wide Field of view Sensor (SeaWiFS) data collected during the MFSPP have been used to examine spatial and temporal variability of SST and chlorophyll (Chl) in the Adriatic Sea. Flows along the Albanian and the Italian coasts can be distinguished year-round in the monthly averaged Chl but only in the colder months in the monthly averaged SST's. The Chl monthly-averaged fields supply less information on circulation features away from coastal boundaries and where conditions are generally oligotrophic, except for the early spring bloom in the Southern Adriatic Gyre. To better characterise the year-to-year and seasonal variability, exploratory data analysis techniques, particularly the plotting of multiple Chl-SST histograms, are employed to make joint quantitative use of monthly-averaged fields. Modal water mass (MW), corresponding to the Chl-SST pairs in the neighbourhood of the maximum of each monthly histogram, are chosen to represent the temporal and spatial evolution of the prevalent processes and their variability in the Adriatic Sea. Over an annual cycle, the MW followed a triangular path with the most pronounced seasonal and interannual variations in both Chl-SST properties and spatial distributions of the MW in the colder part of the year. The winter of 1999 is the colder (by at least 0.5 deg C) and most eutrophic (by 0.2 mg/m 3). The fall of the year 2000 is characterised by the lack of cooling in the month of November that was observed in the previous year. In addition to characterising the MW, the two-dimensional histogram technique allows a distinction to be made between different months in terms of the spread of SST values at a given Chl concentration. During spring and summer, the spread is minimal indicating surface homothermal conditions. In fall and winter, on the other hand, a spread of points suggesting a linear negative correlation between SST and Chl is found. This behaviour is related to the high nutrient content of cooler water associated with upwelling or the Po River fresh water outflow.

  4. Interannual to decadal summer drought variability over Europe and its relationship with global sea surface temperature

    NASA Astrophysics Data System (ADS)

    Ionita, Monica; Lohmann, Gerrit; Rimbu, Norel; Chelcea, Silvia

    2010-05-01

    Variability and predictability of European summer drought conditions during observational period is investigated. The dominat patterns of European drought and their associated large-scale climatic anomalies are identified through canonical correlation analysis (CCA) of the field of self calibrating Palmer Drought Severity Index (PDSI) and global sea surface temperature (SST) anomalies. At interannual time scales we identified patterns of drought variability which are optimally correlated with SST patterns from previous years. The time lag between drought and SST anomaly patterns can provide valuable skill for the prediction of drought conditions over Europe on interannual time scales. Significant lag-correlation between drought patterns and the North Atlantic Oscillation (NAO) suggests that NAO can be used also as a potential predictor of drought European patterns at interannual time scales. The global trend in temperature, the North Atlantic Oscillation (NAO) and the Atlantic Multidecadal Oscillation (AMO) play a significant role in establishing the drought conditions over Europe at multidecadal time scales. The influences of these climatic patterns on drought conditions at multidecadal time scales were identified also through CCA. The first PDSI pattern (CCA1) shows a dipole-like structure between the central Europe and the northern part of the Scandinavian Peninsula. The corresponding SST pattern is a mixture between the global SST trend and the abrupt shift in the 1970s. Wet (dry) conditions over central Europe (Scandinavia) are associated with a strong positive SST center south of Greenland and a strong negative center over the European coast and the North Sea. The third mode (CCA3) identifies a multidecadal scale variation, strongly related to summer drought conditions over the southern part of the Scandinavian Peninsula, the south-eastern part of Europe and the western part of Russia. The corresponding SST pattern shows SST anomalies in the Atlantic basin similar to those associated with AMO. The AMO index and the canonical time series associated to CCA3 are significantly correlated. Possible drought conditions over Europe in the next decades based on the relationships between large-scale SST patterns and drought conditions over Europe, established in our study, are discussed.

  5. Temperature Dependence of 207Pb MAS Spectra of Solid Lead Nitrate. An Accurate, Sensitive Thermometer for Variable-Temperature MAS

    NASA Astrophysics Data System (ADS)

    Bielecki, Anthony; Burum, Douglas P.

    The remarkably sensitive temperature dependence of the 207Pb chemical shift in magic-angle-spinning (MAS) spectra of lead nitrate provides an excellent method for thermometry in solid-state NMR. The temperature dependence is uniform over a range of at least -130 to +150°C, and also the NMR sensitivity and linewidth are very favorable. It is demonstrated that lead nitrate can be used in MAS probes to measure sample temperature changes, temperature gradients, MAS heating effects, and the dynamics of temperature jumps.

  6. The Role of Auxiliary Variables in Deterministic and Deterministic-Stochastic Spatial Models of Air Temperature in Poland

    NASA Astrophysics Data System (ADS)

    Szymanowski, Mariusz; Kryza, Maciej

    2015-11-01

    Our study examines the role of auxiliary variables in the process of spatial modelling and mapping of climatological elements, with air temperature in Poland used as an example. The multivariable algorithms are the most frequently applied for spatialization of air temperature, and their results in many studies are proved to be better in comparison to those obtained by various one-dimensional techniques. In most of the previous studies, two main strategies were used to perform multidimensional spatial interpolation of air temperature. First, it was accepted that all variables significantly correlated with air temperature should be incorporated into the model. Second, it was assumed that the more spatial variation of air temperature was deterministically explained, the better was the quality of spatial interpolation. The main goal of the paper was to examine both above-mentioned assumptions. The analysis was performed using data from 250 meteorological stations and for 69 air temperature cases aggregated on different levels: from daily means to 10-year annual mean. Two cases were considered for detailed analysis. The set of potential auxiliary variables covered 11 environmental predictors of air temperature. Another purpose of the study was to compare the results of interpolation given by various multivariable methods using the same set of explanatory variables. Two regression models: multiple linear (MLR) and geographically weighted (GWR) method, as well as their extensions to the regression-kriging form, MLRK and GWRK, respectively, were examined. Stepwise regression was used to select variables for the individual models and the cross-validation method was used to validate the results with a special attention paid to statistically significant improvement of the model using the mean absolute error (MAE) criterion. The main results of this study led to rejection of both assumptions considered. Usually, including more than two or three of the most significantly correlated auxiliary variables does not improve the quality of the spatial model. The effects of introduction of certain variables into the model were not climatologically justified and were seen on maps as unexpected and undesired artefacts. The results confirm, in accordance with previous studies, that in the case of air temperature distribution, the spatial process is non-stationary; thus, the local GWR model performs better than the global MLR if they are specified using the same set of auxiliary variables. If only GWR residuals are autocorrelated, the geographically weighted regression-kriging (GWRK) model seems to be optimal for air temperature spatial interpolation.

  7. Variable temperature film and contact resistance measurements on operating n-channel organic thin film transistors

    NASA Astrophysics Data System (ADS)

    Chesterfield, Reid J.; McKeen, John C.; Newman, Christopher R.; Frisbie, C. Daniel; Ewbank, Paul C.; Mann, Kent R.; Miller, Larry L.

    2004-06-01

    We report structural and electrical properties in thin films of an n-channel organic semiconductor, N,N'-dipentyl-3,4,9,10-perylene tetracarboxylic dimide (PTCDI-C5). The structure of polycrystalline thin films of PTCDI-C5 was studied using x-ray diffraction and atomic force microscopy. Films order with single crystal-like packing, and the direction of π-π overlap is in the substrate plane. Organic thin film transistors (OTFTs) based on PTCDI-C5 were fabricated on hydrophobic and hydrophilic substrates. OTFTs showed effective mobility as high as 0.1 cm2/V s. Contact resistance of operating OTFTs was studied using resistance versus length plots and a four-probe method for three different contact metals (Au, Ag, Ca). Typical OTFTs had a specific contact resistance of 8×104 Ω cm at high gate voltage. There was no dependence of contact resistance with contact metal. Variable temperature measurements revealed that film resistance in the OTFT was activated in the temperature range 100-300 K, with typical activation energies of 60-80 meV. Contact resistance showed similar activated behavior, implying that the Schottky barrier at the contact is not the limiting resistance for the contact. Film resistance data showed a Meyer-Neldel relationship with characteristic energy EMN=20-25 meV, for various samples. The common TFT instability of threshold voltage shift (TVS) was observed in PTCDI-C5 OTFTs. A model is proposed to explain positive TVS in gate bias stress and oxygen exposure experiments. The model is based on the formation of a metastable complex between PTCDI-C5 and oxygen, which creates a deep acceptor-like trap state.

  8. 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

  9. Field study and simulation of diurnal temperature effects on infiltration and variably saturated flow beneath an ephemeral stream

    USGS Publications Warehouse

    Ronan, A.D.; Prudic, D.E.; Thodal, C.E.; Constantz, J.

    1998-01-01

    Two experiments were performed to investigate flow beneath an ephemeral stream and to estimate streambed infiltration rates. Discharge and stream-area measurements were used to determine infiltration rates. Stream and subsurface temperatures were used to interpret subsurface flow through variably saturated sediments beneath the stream. Spatial variations in subsurface temperatures suggest that flow beneath the streambed is dependent on the orientation of the stream in the canyon and the layering of the sediments. Streamflow and infiltration rates vary diurnally: Stream flow is lowest in late afternoon when stream temperature is greatest and highest in early morning when stream temperature is least. The lower afternoon streamflow is attributed to increased infiltration rates; evapotranspiration is insufficient to account for the decreased streamflow. The increased infiltration rates are attributed to viscosity effects on hydraulic conductivity from increased stream temperatures. The first set of field data was used to calibrate a two-dimensional variably saturated flow model that includes heat transport. The model was calibrated to (1) temperature fluctuations in the subsurface and (2) infiltration rates determined from measured stream flow losses. The second set of field data was to evaluate the ability to predict infiltration rates on the basis of temperature measurements alone. Results indicate that the variably saturated subsurface flow depends on downcanyon layering of the sediments. They also support the field observations in indicating that diurnal changes in infiltration can be explained by temperature dependence of hydraulic conductivity. Over the range of temperatures and flows monitored, diurnal stream temperature changes can be used to estimate streambed infiltration rates. It is often impractical to maintain equipment for determining infiltration rates by traditional means; however, once a model is calibrated using both infiltration and temperature data, only relatively inexpensive temperature monitoring can later yield infiltration rates that are within the correct order of magnitude.

  10. Design of a High Temperature Radiator for the Variable Specific Impulse Magnetoplasma Rocket

    NASA Technical Reports Server (NTRS)

    Sheth, Rubik B.; Ungar, Eugene K.; Chambliss, Joe P.

    2012-01-01

    The Variable Specific Impulse Magnetoplasma Rocket (VASIMR), currently under development by Ad Astra Rocket Company (Webster, TX), is a unique propulsion system that could change the way space propulsion is performed. VASIMR's efficiency, when compared to that of a conventional chemical rocket, reduces the propellant needed for exploration missions by a factor of 10. Currently plans include flight tests of a 200 kW VASIMR system, titled VF-200, on the International Space Station (ISS). The VF-200 will consist of two 100 kW thruster units packaged together in one engine bus. Each thruster core generates 27 kW of waste heat during its 15 minute firing time. The rocket core will be maintained between 283 and 573 K by a pumped thermal control loop. The design of a high temperature radiator is a unique challenge for the vehicle design. This paper will discuss the path taken to develop a steady state and transient-based radiator design. The paper will describe the radiator design option selected for the VASIMR thermal control system for use on ISS, and how the system relates to future exploration vehicles.

  11. 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.

  12. Relationship between the interannual variability of satellite-observed fires and sea surface temperature anomalies

    NASA Astrophysics Data System (ADS)

    Chen, Y.; Randerson, J. T.; Morton, D. C.; DeFries, R. S.; Collatz, G. J.; Kasibhatla, P. S.; Giglio, L.; Jin, Y.; Marlier, M.

    2011-12-01

    Fire is a worldwide phenomenon that occurs in multiple biomes and regions, and has large impacts on ecosystems, air quality, and global climate. High fire years are often associated with an extended dry season and anomalously low levels of precipitation. Sea surface temperatures (SST) may regulate the precipitation variability on land through teleconnections. Here we investigated the relationship between year-to-year changes in satellite-derived estimates of fire activity and SST anomalies. Using South America as an example, we demonstrated an approach to predict regional annual fire season severity with 3-5 month lead times. We found that the Oceanic Niño Index (ONI) was correlated with interannual fire activity in the eastern Amazon whereas the Atlantic Multidecadal Oscillation (AMO) index was more closely linked with fires in the southern and southwestern Amazon. We then extended this approach to examine the relationship between fire occurrences and SSTs for other important fire regions, using SST anomalies from different regions within the Pacific, Atlantic, and Indian Oceans. We determined regions where SST changes had significant impacts on the annual fire season severity, as well as the optimal lead times of fire prediction for each region. This study will be of use in several different ways to inform mitigation and adaptation strategies related to climate change.

  13. Decadal variability of Russian winter snow accumulation and its associations with Atlantic sea surface temperature anomalies

    NASA Astrophysics Data System (ADS)

    Ye, Hengchun

    2000-11-01

    Russian winter snow depth data over a 48-year period (1936-1983) are analysed to reveal variation characteristics and associations to Atlantic sea surface temperature (SST) anomalies using methods of rotated principal component analysis (RPCA), singular spectrum analysis (SSA), and singular value decomposition (SVD) analysis.The study demonstrates that four time scales (4 years interannual, 11.8 years quasidecadal, 20 years bi-decadal and trend) characterize Russian winter snow depth variations. The decadal and longer time scale variations are found to be significantly associated with Atlantic SST anomalies. The trend, which occurred over much of the study region, is associated with SST trends over the northern north and tropical south Atlantic. Bi-decadal snow depth variation over central Siberia is associated with western tropical north Atlantic SSTs. A quasi-decadal variation over western European Russia is connected to a major Atlantic SST variation pattern of opposite signs over alternative latitudinal belts.This study suggests that the connections between the Atlantic Ocean and regional climate may be better reflected at decadal time scales than interannual and seasonal ones, as the dominant variability over the ocean is at slow modes.

  14. Temperature-driven global sea-level variability in the Common Era

    PubMed Central

    Kopp, Robert E.; Kemp, Andrew C.; Bittermann, Klaus; Horton, Benjamin P.; Donnelly, Jeffrey P.; Gehrels, W. Roland; Hay, Carling C.; Mitrovica, Jerry X.; Morrow, Eric D.; Rahmstorf, Stefan

    2016-01-01

    We assess the relationship between temperature and global sea-level (GSL) variability over the Common Era through a statistical metaanalysis of proxy relative sea-level reconstructions and tide-gauge data. GSL rose at 0.1 ± 0.1 mm/y (2σ) over 0–700 CE. A GSL fall of 0.2 ± 0.2 mm/y over 1000–1400 CE is associated with ∼0.2 °C global mean cooling. A significant GSL acceleration began in the 19th century and yielded a 20th century rise that is extremely likely (probability P≥0.95) faster than during any of the previous 27 centuries. A semiempirical model calibrated against the GSL reconstruction indicates that, in the absence of anthropogenic climate change, it is extremely likely (P=0.95) that 20th century GSL would have risen by less than 51% of the observed 13.8±1.5 cm. The new semiempirical model largely reconciles previous differences between semiempirical 21st century GSL projections and the process model-based projections summarized in the Intergovernmental Panel on Climate Change’s Fifth Assessment Report. PMID:26903659

  15. Multiproxy paleolimnological evidence of Holocene temperature and precipitation variability from the Eastern Cordillera, Colombia

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    The late Holocene was characterized by a number of significant, widespread multi-century climate anomalies, the most prominent and well documented of which are the Little Ice Age and the Medieval Warm Period. Existing paleoclimate reconstructions from South and Central America provide evidence for anomalous climate conditions during these time periods but the spatial and temporal resolution of existing records is limited and quantitative data on the magnitudes of these events is lacking. These limitations make it difficult to fully evaluate the causes and large scale impacts of these apparently global events. Here, we present new high-resolution multiproxy lacustrine records of late Holocene climate change in the Eastern Cordillera of Colombia over the last 2 millennia by combining high-resolution core scanning approaches with molecular and stable isotope analysis of lipid biomarkers. Preliminary paleoclimate reconstructions from these archives suggest that the northern tropics of South America strongly reflect global century-scale climate variability over this time period, with significant hydrologic and temperature anomalies that are broadly synchronous with events in the high latitudes of the northern hemisphere. The magnitude and widespread nature of late Holocene century-scale droughts in this region likely had significant ecological and societal impacts in the Eastern Cordillera.

  16. Effects of modeled tropical sea surface temperature variability on coral reef bleaching predictions

    NASA Astrophysics Data System (ADS)

    Van Hooidonk, R. J.

    2011-12-01

    Future widespread coral bleaching and subsequent mortality has been projected with sea surface temperature (SST) data from global, coupled ocean-atmosphere general circulation models (GCMs). While these models possess fidelity in reproducing many aspects of climate, they vary in their ability to correctly capture such parameters as the tropical ocean seasonal cycle and El Nio Southern Oscillation (ENSO) variability. These model weaknesses likely reduce the skill of coral bleaching predictions, but little attention has been paid to the important issue of understanding potential errors and biases, the interaction of these biases with trends and their propagation in predictions. To analyze the relative importance of various types of model errors and biases on coral reef bleaching predictive skill, various intra- and inter-annual frequency bands of observed SSTs were replaced with those frequencies from GCMs 20th century simulations to be included in the Intergovernmental Panel on Climate Change (IPCC) 5th assessment report. Subsequent thermal stress was calculated and predictions of bleaching were made. These predictions were compared with observations of coral bleaching in the period 1982-2007 to calculate skill using an objective measure of forecast quality, the Peirce Skill Score (PSS). This methodology will identify frequency bands that are important to predicting coral bleaching and it will highlight deficiencies in these bands in models. The methodology we describe can be used to improve future climate model derived predictions of coral reef bleaching and it can be used to better characterize the errors and uncertainty in predictions.

  17. The change of hemodynamics and heart rate variability on bathing by the gap of water temperature.

    PubMed

    Kataoka, Y; Yoshida, F

    2005-10-01

    Bathing in Japanese style may carry negative effects as water pressure on the chest and thermal stimulus on hemodynamics take place. We have explored the influence of bathing in high temperature water on the change of heart rate variability (HRV). Fourteen young healthy male adults, ageing in range from 28 to 42 years old (the average was 35.8 years old) were selected and took a hot water bath (38 and 41 degrees C) for 15 min long. Bathing in 38 degrees C water brought no significant change in heart rate (HR) and blood pressure (BP), and the HR in 41 degrees C increased in early stage. In HRV, high frequency (HF) power did not have significant change with little increase in early stages of bathing in 38 degrees C and decreased continuously in 41 degrees C. Low frequency (LF) power and very low frequency (VLF) power decreased gradually in later stages of bathing, but the degree of decrease was larger in 41 degrees C. In this study, data concerning dizziness after bathing at 41 degrees C was obtained (we named it as a "dizzy case"). HF and LF trends in this case followed the same pattern in comparison with others' average, but the decrease was larger. Additionally, there was no increase in the LF/HF at later stage of bathing. It is thought that this reflects a decreased in autonomic nerve activity. In normal subjects the VLF increased in later stages of 38 and 41 degrees C bathing, but in the dizziness-experiencing subject, the increase was very significant. It is conceivable that this reflected excessive parasympathetic reflex. Except the dizzy case HF decreased continuously in later stage of bathing in both 38 and 41 degrees C, but VLF slightly increased. Recently there was an express opinion that the VLF correlates with the prognosis; therefore the change of VLF in this study is very interesting. Based upon the results of this study we propose that the optimum period of time for bathing in water 41 degrees C in temperature is 5 min or less, and that for water 38 degrees C in temperature is 10 min or less. PMID:16275514

  18. The variability of winter high temperature extremes in Romania and its relationship with large-scale atmospheric circulation

    NASA Astrophysics Data System (ADS)

    Rimbu, N.; Stefan, S.; Necula, C.

    2015-07-01

    The frequency variability of extreme high winter temperature as recorded at 85 meteorological stations from Romania during 1962-2010 period and its relationship with large-scale atmospheric circulation was investigated. An Empirical Orthogonal Function analysis reveals that large part of the extreme temperature frequency variability is common to all stations suggesting a strong influence of large-scale circulation anomalies. The North Atlantic Oscillation, West Pacific, East Atlantic, and Scandinavian patterns are related with extreme temperature frequency variability. We show that the East Atlantic Oscillation controls a significant part of interannual extreme high temperature variability over Romania via advection of warm air from the west. In addition, a strong relationship between blocking activity and frequency of extreme high temperature events in Romania was found. High blocking activity in the (20°W-70°E) sector is related with relatively strong advection of cold air over the country during winter. On the other hand, low blocking activity in the same sector is related with weak advection of relatively cold air in the region. Moreover, the blocking frequency in this sector is modulated mainly by the East Atlantic Oscillation.

  19. 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.

  20. 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...

  1. JPL field measurements at the Finney County, Kansas, test site, October 1976: Meteorological variables, surface reflectivity, surface and subsurface temperatures

    NASA Technical Reports Server (NTRS)

    Kahle, A. B.; Schieldge, J.; Paley, H. N.

    1977-01-01

    Data collected at the Finney County, Kansas test site as part of the Joint Soil Moisture Experiment (JSME) are presented here, prior to analysis, to provide all JSME investigators with an immediate source of primary information. The ground-truth measurements were taken to verify and complement soil moisture data taken by microwave and infrared sensors during aircraft overflights. Measurements were made of meteorological variables (air speed, temperature, relative humidity, and rainfall), surface reflectivity, and temperatures at and below the surface.

  2. Climate Change Impact Assessment in Pacific North West Using Copula based Coupling of Temperature and Precipitation variables

    NASA Astrophysics Data System (ADS)

    Qin, Y.; Rana, A.; Moradkhani, H.

    2014-12-01

    The multi downscaled-scenario products allow us to better assess the uncertainty of the changes/variations of precipitation and temperature in the current and future periods. Joint Probability distribution functions (PDFs), of both the climatic variables, might help better understand the interdependence of the two, and thus in-turn help in accessing the future with confidence. Using the joint distribution of temperature and precipitation is also of significant importance in hydrological applications and climate change studies. In the present study, we have used multi-modelled statistically downscaled-scenario ensemble of precipitation and temperature variables using 2 different statistically downscaled climate dataset. The datasets used are, 10 Global Climate Models (GCMs) downscaled products from CMIP5 daily dataset, namely, those from the Bias Correction and Spatial Downscaling (BCSD) technique generated at Portland State University and from the Multivariate Adaptive Constructed Analogs (MACA) technique, generated at University of Idaho, leading to 2 ensemble time series from 20 GCM products. Thereafter the ensemble PDFs of both precipitation and temperature is evaluated for summer, winter, and yearly periods for all the 10 sub-basins across Columbia River Basin (CRB). Eventually, Copula is applied to establish the joint distribution of two variables enabling users to model the joint behavior of the variables with any level of correlation and dependency. Moreover, the probabilistic distribution helps remove the limitations on marginal distributions of variables in question. The joint distribution is then used to estimate the change trends of the joint precipitation and temperature in the current and future, along with estimation of the probabilities of the given change. Results have indicated towards varied change trends of the joint distribution of, summer, winter, and yearly time scale, respectively in all 10 sub-basins. Probabilities of changes, as estimated by the joint precipitation and temperature, will provide useful information/insights for hydrological and climate change predictions.

  3. Application of Differential Transform Method to Thermoelastic Problem for Annular Disks of Variable Thickness with Temperature-Dependent Parameters

    NASA Astrophysics Data System (ADS)

    Chiba, Ryoichi

    2012-02-01

    This article analyzes the one-dimensional steady temperature field and related thermal stresses in an annular disk of variable thickness that has a temperature-dependent heat transfer coefficient and is capable of temperature-dependent internal heat generation. The temperature dependencies of the thermal conductivity, Young's modulus, and the coefficient of linear thermal expansion of the disk are considered, whereas Poisson's ratio is assumed to be constant. The differential transform method (DTM) is employed to analyze not only the nonlinear heat conduction but also the resulting thermal stresses. Analytical solutions are developed for the temperature and thermal stresses in the form of simple power series. Numerical calculations are performed for an annular cooling/heating fin of variable thickness. Numerical results show that the sufficiently converged analytical solutions are in good agreement with the solutions obtained by the Adomian decomposition method and give the effects of the temperature-dependent parameters on the temperature and thermal stress profiles in the disk. The DTM is useful as a new analytical method for solving thermoelastic problems for a body with temperature-dependent parameters including material properties.

  4. Spatio-temporal variability in remotely sensed land surface temperature, and its relationship with physiographic variables in the Russian Altay Mountains

    NASA Astrophysics Data System (ADS)

    Van De Kerchove, R.; Lhermitte, S.; Veraverbeke, S.; Goossens, R.

    2013-02-01

    Spatio-temporal variability in energy fluxes at the earth's surface implies spatial and temporal changes in observed land surface temperatures (LST). These fluxes are largely determined by variation in meteorological conditions, surface cover and soil characteristics. Consequently, a change in these parameters will be reflected in a different temporal LST behavior which can be observed by remotely sensed time series. Therefore, the objective of this paper is to perform a quantitative analysis on the parameters that determine this variability in LST to estimate the impact of changes in these parameters on the surface thermal regime. This study was conducted in the Russian Altay Mountains, an area characterized by strong gradients in meteorological conditions and surface cover. Spatio-temporal variability in LST was assessed by applying the fast Fourier transform (FFT) on 8 year of MODIS Aqua LST time series, herein considering both day and nighttime series as well as the diurnal difference. This FFT method was chosen as it allows to discriminate significant periodics, and as such enables distinction between short-term weather components, and strong, climate related, periodic patterns. A quantitative analysis was based on multiple linear regression models between the calculated, significant Fourier components (i.e. the annual and average component) and five physiographic variables representing the regional variability in meteorological conditions and surface cover. Physiographic predictors were elevation, potential solar insolation, topographic convergence, vegetation cover and snow cover duration. Results illustrated the strong inverse relationship between averaged daytime and diurnal difference LST and snow duration, with a Radj2 of 0.85 and 0.60, respectively. On the other hand, nocturnal LST showed a strong connection with elevation and the amount of vegetation cover. Amplitudes of the annual harmonic experienced both for daytime and for nighttime LST similar trends with the set of physiographic variables - with stronger relationships at night. As such, topographic convergence was found to be the principal single predictor which demonstrated the importance of severe temperature inversions in the region. Furthermore, limited contribution of the physiographic predictors to the observed variation in the annual signal of the diurnal difference was retrieved, although a significant phase divergence was noticed between the majority of the study region and the perennial snowfields. Hence, this study gives valuable insights into the complexity of the spatio-temporal variability in LST, which can be used in future studies to estimate the ecosystems' response on changing climatic conditions.

  5. Mechanisms Controlling Variability of the Interhemispheric Sea Surface Temperature Gradient in the Tropical Atlantic.

    NASA Astrophysics Data System (ADS)

    Wagner, Richard G.

    1996-09-01

    The seasonal evolution of sea surface temperature (SST) fields in the tropical Atlantic is explored for composites of extremely STRONG and WEAK northward SST gradients, because these are known to control the basinwide pressure gradient, latitude position of the intertopical convergence zone (ITCZ), and regional rainfall. Aimed at the origin and maintenance of anomalies in the interhemispheric SST gradient, and using surface and subsurface marine observations, differences in forcing of SST patterns from surface heat fluxes and entrainment are scaled by calendar-monthly mixed layer depth, and compared to the observed evolution of SST. For years with a STRONG as compared to WEAK gradient in boreal winter, a substantial portion of anomalous SST evolution from September to February can be attributed to departures in SST forcing by latent heat transfer: in the North Atlantic, strengthened northeast trades associated with a stronger North Atlantic high promote enhanced evaporative cooling, while weakened southeast trades reduce latent heat loss, intensifying seasonal warming. During March to August, Ekman upwelling in the north contributes less cooling to anomalously cold surface waters, while in the south autumn entrainment cools the upper layer more rapidly. The resulting decay of both cold anomalies in the north and warm anomalies in the south reduces the anomalously strong SST gradient. A pronounced decadal-scale trend toward a stronger northward SST gradient in January is reflected in an enhancement of Northeast Brazil rainfall, which is strongly correlated to the March-April interhemispheric SST gradient; both Pacific SST and the Atlantic SST gradient in January are associated with variability in the March-April gradient; however, SST in the Pacific and the SST gradient in the Atlantic are uncorrelated in January.

  6. 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.

  7. Do walleye pollock exhibit flexibility in where or when they spawn based on variability in water temperature?

    NASA Astrophysics Data System (ADS)

    Bacheler, Nathan M.; Ciannelli, Lorenzo; Bailey, Kevin M.; Bartolino, Valerio

    2012-06-01

    Environmental variability is increasingly recognized as a primary determinant of year-class strength of marine fishes by directly or indirectly influencing egg and larval development, growth, and survival. Here we examined the role of annual water temperature variability in determining when and where walleye pollock (Theragra chalcogramma) spawn in the eastern Bering Sea. Walleye pollock spawning was examined using both long-term ichthyoplankton data (N=19 years), as well as with historical spatially explicit, foreign-reported, commercial catch data occurring during the primary walleye pollock spawning season (February-May) each year (N=22 years in total). We constructed variable-coefficient generalized additive models (GAMs) to relate the spatially explicit egg or adult catch-per-unit-effort (CPUE) to predictor variables including spawning stock biomass, season, position, and water temperature. The adjusted R2 value was 63.1% for the egg CPUE model and 35.5% for the adult CPUE model. Both egg and adult GAMs suggest that spawning progresses seasonally from Bogoslof Island in February and March to Outer Domain waters between the Pribilof and Unimak Islands by May. Most importantly, walleye pollock egg and adult CPUE was predicted to generally increase throughout the study area as mean annual water temperature increased. These results suggest low interannual variability in the spatial and temporal dynamics of walleye pollock spawning regardless of changes in environmental conditions, at least at the spatial scale examined in this study and within the time frame of decades.

  8. 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

  9. 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…

  10. Variability in solar radiation and temperature explains observed patterns and trends in tree growth rates across four tropical forests

    PubMed Central

    Dong, Shirley Xiaobi; Davies, Stuart J.; Ashton, Peter S.; Bunyavejchewin, Sarayudh; Supardi, M. N. Nur; Kassim, Abd Rahman; Tan, Sylvester; Moorcroft, Paul R.

    2012-01-01

    The response of tropical forests to global climate variability and change remains poorly understood. Results from long-term studies of permanent forest plots have reported different, and in some cases opposing trends in tropical forest dynamics. In this study, we examined changes in tree growth rates at four long-term permanent tropical forest research plots in relation to variation in solar radiation, temperature and precipitation. Temporal variation in the stand-level growth rates measured at five-year intervals was found to be positively correlated with variation in incoming solar radiation and negatively related to temporal variation in night-time temperatures. Taken alone, neither solar radiation variability nor the effects of night-time temperatures can account for the observed temporal variation in tree growth rates across sites, but when considered together, these two climate variables account for most of the observed temporal variability in tree growth rates. Further analysis indicates that the stand-level response is primarily driven by the responses of smaller-sized trees (less than 20 cm in diameter). The combined temperature and radiation responses identified in this study provide a potential explanation for the conflicting patterns in tree growth rates found in previous studies. PMID:22833269

  11. Quantifying spatial and temporal variabilities of microwave brightness temperature over the U.S. Southern Great Plains

    NASA Technical Reports Server (NTRS)

    Choudhury, B. J.; Owe, M.; Ormsby, J. P.; Chang, A. T. C.; Wang, J. R.; Goward, S. N.; Golus, R. E.

    1987-01-01

    Spatial and temporal variabilities of microwave brightness temperature over the U.S. Southern Great Plains are quantified in terms of vegetation and soil wetness. The brightness temperatures (TB) are the daytime observations from April to October for five years (1979 to 1983) obtained by the Nimbus-7 Scanning Multichannel Microwave Radiometer at 6.6 GHz frequency, horizontal polarization. The spatial and temporal variabilities of vegetation are assessed using visible and near-infrared observations by the NOAA-7 Advanced Very High Resolution Radiometer (AVHRR), while an Antecedent Precipitation Index (API) model is used for soil wetness. The API model was able to account for more than 50 percent of the observed variability in TB, although linear correlations between TB and API were generally significant at the 1 percent level. The slope of the linear regression between TB and API is found to correlate linearly with an index for vegetation density derived from AVHRR data.

  12. Effects of the interannual variability in chlorophyll concentrations on sea surface temperatures in the east tropical Indian Ocean

    NASA Astrophysics Data System (ADS)

    Ma, Jinfeng; Liu, Hailong; Lin, Pengfei; Zhan, Haigang

    2015-10-01

    The effects of interannual variability in chlorophyll concentrations on sea surface temperatures in the east tropical Indian Ocean (ETIO) during two positive Indian Ocean Dipole (IOD) events (in the boreal fall of 1997 and 2006) are investigated; this is done through two ocean model experiments, one with and one without the interannual variability of chlorophyll concentrations. A comparison of the two chlorophyll perturbation experiments reveals that, in contrast to the cooling effects at the seasonal time scale, increased chlorophyll concentrations during positive IOD events lead to an increase in the sea surface temperatures within the ETIO. Although upward velocity is enhanced (with a cooling effect), this does not counterbalance the increase in solar heating caused by the increased chlorophyll concentrations. This interannual variability of chlorophyll concentrations in the ETIO could reduce the amplitude of the IOD by about 6%.

  13. Variable Temperature Stress in the Nematode Caenorhabditis elegans (Maupas) and Its Implications for Sensitivity to an Additional Chemical Stressor

    PubMed Central

    Svendsen, Claus; Spurgeon, David J.

    2016-01-01

    A wealth of studies has investigated how chemical sensitivity is affected by temperature, however, almost always under different constant rather than more realistic fluctuating regimes. Here we compared how the nematode Caenorhabditis elegans responds to copper at constant temperatures (8–24°C) and under fluctuation conditions of low (±4°C) and high (±8°C) amplitude (averages of 12, 16, 20°C and 16°C respectively). The DEBkiss model was used to interpret effects on energy budgets. Increasing constant temperature from 12–24°C reduced time to first egg, life-span and population growth rates consistent with temperature driven metabolic rate change. Responses at 8°C did not, however, accord with this pattern (including a deviation from the Temperature Size Rule), identifying a cold stress effect. High amplitude variation and low amplitude variation around a mean temperature of 12°C impacted reproduction and body size compared to nematodes kept at the matching average constant temperatures. Copper exposure affected reproduction, body size and life-span and consequently population growth. Sensitivity to copper (EC50 values), was similar at intermediate temperatures (12, 16, 20°C) and higher at 24°C and especially the innately stressful 8°C condition. Temperature variation did not increase copper sensitivity. Indeed under variable conditions including time at the stressful 8°C condition, sensitivity was reduced. DEBkiss identified increased maintenance costs and increased assimilation as possible mechanisms for cold and higher copper concentration effects. Model analysis of combined variable temperature effects, however, demonstrated no additional joint stressor response. Hence, concerns that exposure to temperature fluctuations may sensitise species to co-stressor effects seem unfounded in this case. PMID:26784453

  14. Variable Temperature Stress in the Nematode Caenorhabditis elegans (Maupas) and Its Implications for Sensitivity to an Additional Chemical Stressor.

    PubMed

    Cedergreen, Nina; Nørhave, Nils Jakob; Svendsen, Claus; Spurgeon, David J

    2016-01-01

    A wealth of studies has investigated how chemical sensitivity is affected by temperature, however, almost always under different constant rather than more realistic fluctuating regimes. Here we compared how the nematode Caenorhabditis elegans responds to copper at constant temperatures (8-24°C) and under fluctuation conditions of low (±4°C) and high (±8°C) amplitude (averages of 12, 16, 20°C and 16°C respectively). The DEBkiss model was used to interpret effects on energy budgets. Increasing constant temperature from 12-24°C reduced time to first egg, life-span and population growth rates consistent with temperature driven metabolic rate change. Responses at 8°C did not, however, accord with this pattern (including a deviation from the Temperature Size Rule), identifying a cold stress effect. High amplitude variation and low amplitude variation around a mean temperature of 12°C impacted reproduction and body size compared to nematodes kept at the matching average constant temperatures. Copper exposure affected reproduction, body size and life-span and consequently population growth. Sensitivity to copper (EC50 values), was similar at intermediate temperatures (12, 16, 20°C) and higher at 24°C and especially the innately stressful 8°C condition. Temperature variation did not increase copper sensitivity. Indeed under variable conditions including time at the stressful 8°C condition, sensitivity was reduced. DEBkiss identified increased maintenance costs and increased assimilation as possible mechanisms for cold and higher copper concentration effects. Model analysis of combined variable temperature effects, however, demonstrated no additional joint stressor response. Hence, concerns that exposure to temperature fluctuations may sensitise species to co-stressor effects seem unfounded in this case. PMID:26784453

  15. Patterns in Temporal Variability of Temperature, Oxygen and pH along an Environmental Gradient in a Coral Reef

    PubMed Central

    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

  16. 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

  17. Upper atmosphere temperature variability from 100 to 280 km over a full solar cycle - the WINDII perspective

    NASA Astrophysics Data System (ADS)

    Shepherd, M. G.; Cho, Y.; Shepherd, G. G.

    2013-12-01

    The Wind Imaging Interferometer (WINDII) flown on the Upper Atmosphere Research Satellite (UARS) provides a means of examining variability in the thermospheric temperature and density over the altitude range from 70 to 300 km over a period of more than 10 years (from 1991 to 2003) through observations of Rayleigh scattering temperatures (70-95 km), Doppler temperatures (90-300 km), and atomic oxygen airglow emissions (90-300 km). The observation period encompasses two solar maxima (1992-1993 and 2000-2001) and one solar minimum (1996-1997). The original WINDII dataset (1991-1997) was recently extended to 2003 with observations not analysed before thus bridging the gap between the UARS and TIMED satellite missions and providing a means for examining thermospheric parameter variability over two solar cycles. The variability of airglow Doppler temperature with height from above the mesosphere to 300 km will be examined for solar maximum and minimum conditions, with an emphasis on the 100-160 km height regime where significant coupling between the lower and the upper thermosphere exists; neutral density and temperature are the key to understanding the upper atmosphere thermal response to perturbations from below. Some preliminary results from this study will be presented and discussed.

  18. The variability of nonmigrating tides detected from TIMED/SABER observations

    NASA Astrophysics Data System (ADS)

    Li, Xing; Wan, Weixing; Ren, Zhipeng; Liu, Libo; Ning, Baiqi

    2015-12-01

    This paper deals with the variability of the nonmigrating tides detected from the observation of the SABER instrument on board the TIMED satellite during the 11 year solar period from 2002 to 2012. The longitudinal wave number spectra with 1 day resolution were first estimated from the temperature data measured at the MLT altitudes (70-110 km) and at the lower midlatitudes and low latitudes (between ±45°). Then we used the wave number 4 component to obtain the nonmigrating tides in which the dominant component DE3 was further analyzed in detail. We found that the properties of the spatial distribution and large time scale variation of the DE3 component are similar to those of the previous works, which used the interpolated data with 2 month resolution. These properties are that the DE3 component occurs mainly at the low latitudes within ±30° and at the altitudes from 90 to 110 km; the tidal amplitude is larger during boreal summer and early autumn, smaller in spring and almost tends to disappear in winter; the component is slightly stronger during the eastward wind QBO phase than the westward phase. Practically, the higher-resolution data were used to reveal the day-to-day variability of the DE3 component. It is found that (1) the variability occurs mainly at the altitudes from 100 to 110 km with a peak at 106 km; (2) it is strong at the low latitudes and peaks around the equator, as well, slightly stronger in the Southern Hemisphere than in northern one; (3) it is considerably larger around solstitial months than equinoctial months; and (4) it would not experience an obvious interannual variation. The day-to-day variability of the DE3 component may be explained by the variance of the absolute amplitudes and the contribution of the wave phases, and the later seems to play more important role.

  19. 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.

  20. Effects of temperature and precipitation on snowpack variability in the Central Rocky Mountains as a function of elevation

    NASA Astrophysics Data System (ADS)

    Sospedra-Alfonso, Reinel; Melton, Joe R.; Merryfield, William J.

    2015-06-01

    We employ a regression-based methodology to study the impact of temperature and precipitation on snowpack variability as a function of elevation in the Central Rocky Mountains. Because of the broad horizontal coverage and thermal heterogeneity of the measurement sites employed, we introduce an elevation correction based on the sites' climatological temperature. For the elevation range investigated (1295-2256 m), and assuming an average atmospheric lapse rate of -6.5°C/km, we find a mostly linear relationship between effective elevation and correlation of temperature or precipitation with snow water equivalent and snowpack duration. We estimate a threshold elevation, 1560 ± 120 m, below (above) which temperature (precipitation) is the main driver of the snowpack. This threshold elevation is robust under a range of assumed atmospheric lapse rates. Locations below this elevation are likely to be affected by projected rising temperatures, with important effects on ecosystems and economic activities dependent on snow.

  1. Early Holocene Centennial-Scale Sea Surface Temperature and Salinity Variability in the Florida Straits

    NASA Astrophysics Data System (ADS)

    Weinlein, W. A.; Schmidt, M. W.; Lynch-Stieglitz, J. M.

    2009-12-01

    Paleoproxy data and modeling studies suggest that Early Holocene (10.5 - 7 kyr BP) climate in the western tropical North Atlantic (TNA) was warmer and wetter than today. Perihelion occurred during boreal summer, resulting in an amplified Early Holocene seasonal cycle and a reorganization of the tropical climate system (Oppo et al., 2007). Trace metal records from the Cariaco Basin (Haug et al., 2001) and ostracod δ18O records from Haiti (Hodell, 1991) suggest a northward shift in the Intertropical Convergence Zone (ITCZ) resulted in decreased evaporation-precipitation values in the western TNA. In addition, the final drainage of large pro-glacial lakes into the North Atlantic at 8.2 kyr BP is thought to have resulted in a meltwater-induced reduction in Atlantic meridional overturning circulation that caused widespread cooling in the circum-Atlantic region (Barber et al., 1999; Clarke et al., 2004; Ellison et al., 2006). In order to reconstruct centennial-scale records of Early Holocene sea surface temperature (SST) and salinity (SSS) variability in the Florida Straits, we will measure δ18O values as well as Mg/Ca and Ba/Ca ratios in the planktonic foraminifera Globigerinoides ruber from two sediment cores recovered from the Florida Straits: KNR166-2 JPC-51 (24°24.70’N, 83°13.14’W, 198 m; ~60-100 cm/kyr sedimentation rate) and KNR166-2 GGC-7 (24°21.50’N, 83°20.90’N, 535 m; ~55 cm/kyr sedimentation rate). SSTs are calculated from Mg/Ca ratios based on a published sediment trap calibration (Anand et al., 2003). Initial measurements of Mg/Ca ratios suggest centennial-scale SST oscillations during the Early Holocene. Calculated SSTs vary from 26.3 to 29.8°C and are within the range of modern seasonal variability for our core locations (25-30°C). Calculated Mg/Ca-SSTs will be combined with G. ruber δ18O values to calculate past δ18Oseawater values (a proxy for SSS) using a laboratory calibrated relationship (Bemis et al., 1998). In addition, Ba/Ca ratios in foraminifera can be used as a qualitative proxy for salinity change resulting riverine input (Weldeab et al., 2007). Laboratory experiments show that Ba+2 incorporation into living planktonic foraminifera shells is linear, dependent primarily on the [Ba+2] of the water in which the shell grows (Lea and Spero, 1994). Riverine water contains much higher concentrations of [Ba+2] relative to seawater. Furthermore, dissolved barium concentrations exhibit a conservative mixing with seawater, resulting in a linear inverse correlation between salinity and [Ba+2] (Coffey et al., 1997; Edmond et al., 1978; Hanor and Chan, 1977). The resulting Ba/Ca can then be used to identify periods of intensified riverine input into the Gulf of Mexico. Finally, we will compare our Florida Straits δ18Oseawater and Ba/Ca-SSS reconstructions with the previously published centennial-scale record of Early Holocene hydrologic change from the northern Gulf of Mexico’s Orca Basin (LoDico et al., 2006).

  2. 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...

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

    NASA Astrophysics Data System (ADS)

    Chu, Peter C.; Lu, Shihua; Chen, Yuchun

    1997-09-01

    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 ?, composite analysis to obtain the monthly mean anomaly relative to the ensemble mean ?, and empirical orthogonal function (EOF) analysis on the residue data relative to ?. The ensemble mean SST field ? has a rather weak horizontal gradient: 29°C near the Borneo coast to 25°-26°C near the southeast China coast. Two areas of evident SST anomalies were found in the monthly ? variation: west of Borneo-Palawan Islands (WBP) and southeast of the southern Vietnam coast (SVC). Four patterns, monsoon and transition each with two out-of-phase structures, were found. During the spring-to-summer transition (March to May) the warm anomaly is formed in the northern SCS with ? located at 112°-119°30'E, 15°-19°30'N. During the fall-to-winter transition (October to November) the northern SCS (north of 12°N) cool anomaly is formed in November with ? located at 108°-115°, 13°-20°N. We performed an EOF analysis on the residue data relative to ? in order to obtain transient and interannual variations of the SST fields. EOF1 accounts for 47% of the variance and represents the northern SCS warm/cool anomaly pattern. EOF2 accounts for 14% of the variance and represents the southern SCS dipole pattern. Strong northern SCS warm anomaly (1°C warmer) appears during October-November 1987 and January-February 1988, and strong northern SCS cool anomaly (1°C cooler) occurs during March 1986 and November 1992. Furthermore, a strong cross correlation between wind stress curl and SST anomalies, computed from the European Centre for Medium-Range Weather Forecast analyzed wind stress data and the NCEP SST data for different lags, shows the existence of an air-sea feedback mechanism in the SCS deep basin.

  4. Trend and Variability of China Precipitation in Spring and Summer: Linkage to Sea Surface Temperatures

    NASA Technical Reports Server (NTRS)

    Yang, Fanglin; Lau, K.-M.

    2004-01-01

    Observational records in the past 50 years show an upward trend of boreal-summer precipitation over central eastern China and a downward trend over northern China. During boreal spring, the trend is upward over southeastern China and downward over central eastern China. This study explores the forcing mechanism of these trends in association with the global sea-surface temperature (SST) variations on the interannual and inter-decadal timescales. Results based on Singular Value Decomposition analyses (SVD) show that the interannual variability of China precipitation in boreal spring and summer can be well defined by two centers of actions for each season, which are co-varying with two interannual modes of SSTs. The first SVD modes of precipitation in spring and summer, which are centered in southeastern China and northern China, respectively, are linked to an ENSO-like mode of SSTs. The second SVD modes of precipitation in both seasons are confined to central eastern China, and are primarily linked to SST variations over the warm pool and Indian Ocean. Features of the anomalous 850-hPa winds and 700-Wa geopotential height corresponding to these modes support a physical mechanism that explains the causal links between the modal variations of precipitation and SSTs. On the decadal and longer timescale, similar causal links are found between the same modes of precipitation and SSTs, except for the case of springtime precipitation over central eastern China. For this case, while the interannual mode of precipitation is positively correlated with the interannual variations of SSTs over the warm pool and Indian Ocean; the inter-decadal mode is negatively correlated with a different SST mode, the North Pacific mode. The later is responsible for the observed downward trend of springtime precipitation over central eastern China. For all other cases, both the interannual and inter-decadal variations of precipitation can be explained by the same mode of SSTs. The upward trend of springtime precipitation over southeastern China and downward trend of summertime precipitation over northern China are attributable to the warming trend of the ENSO-like mode. The recent frequent summertime floods over central eastern China are linked to the warming trend of SSTs over the warm pool and Indian Ocean.

  5. Variability of the Structure Parameters of Temperature and Humidity Observed in the Atmospheric Surface Layer Under Unstable Conditions

    NASA Astrophysics Data System (ADS)

    Braam, Miranda; Moene, Arnold F.; Beyrich, Frank

    2014-03-01

    The structure parameters of temperature and humidity are important in scintillometry as they determine the structure parameter of the refractive index of air, the primary atmospheric variable obtained with scintillometers. In this study, we investigate the variability of the logarithm of the Monin-Obukhov-scaled structure parameters (denoted as ) of temperature and humidity. We use observations from eddy-covariance systems operated at three heights (2.5, 50, and 90 m) within the atmospheric surface layer under unstable conditions. The variability of depends on instability and on the size of the averaging window over which is calculated. If instability increases, differences in between upward motions (large ) and downward motions (small ) increase. The differences are, however, not sufficiently large to result in a bimodal probability density function. If the averaging window size increases, the variances of decrease. A linear regression of the variances of versus the averaging window size for various stability classes shows an increase of both the offset and slope (in absolute sense) with increasing instability. For temperature, data from the three heights show comparable results. For humidity, in contrast, the offset and slope are larger at 50 and 90 m than at 2.5 m. In the end we discuss how these findings could be used to assess whether observed differences in along a scintillometer path or aircraft flight leg are just within the range of local variability in or could be attributed to surface heterogeneity. This is important for the interpretation of data measured above a heterogeneous surface.

  6. Glacial-interglacial continental temperature variability in the Beringian Arctic: the MBT/CBT record of Lake El'gygytgyn

    NASA Astrophysics Data System (ADS)

    Castaneda, I. S.; Finkelstein, D. B.; Phu, V.; Brigham-Grette, J.; Wilkie, K. M.; D'anjou, R. M.; Wei, J. H.; Urann, B. M.

    2012-12-01

    In 2009, deep drilling at El'gygytgyn Crater Lake (Far East Russian Arctic) recovered sediments covering the past 3.6 Ma. These sediments provide the first terrestrial Arctic paleoclimate record spanning the Pliocene-Pleistocene from the largest and oldest unglaciated Arctic lake basin. Lake El'gygytgyn sediments thus offer a unique opportunity to examine high-latitude climate variability beyond the 100 Ka interval captured by Greenland ice core records. In this study we utilize an organic geochemical paleothermometer, the MBT/CBT Index based on branched glycerol dialkyl glycerol tetraethers (GDGTs; Weijers et al., 2007), to examine continental temperature variability during several key time intervals of interest. In particular, we focus on Marine Isotope Stages (MIS) 1-6, MIS 9-11, MIS 31 and during the earliest formation of lacustrine sediments in the impact basin in the middle Pliocene. Previous work on Lake El'gygytgyn sediments has identified MIS 11c and MIS 31 as "super" interglacials, which were characterized by significantly warmer temperatures than at present largely based on pollen spectra and modern analog analysis (Melles et al., 2012). Our results show that relative changes in MBT/CBT-derived temperatures display similar overall patterns of glacial-interglacial climate variability noted in temperature reconstructions from Lake El'gygytgyn (Melles et al., 2012) as well as Greenland ice core records, North Atlantic sea surface temperature records (e.g. Lawrence et al., 2010), and the global benthic δ18O stack (Lisiecki and Raymo, 2005). We demonstrate that MBT/CBT is a sensitive proxy for recording temperature variability at Lake El'gygytgyn. Interestingly, while pronounced warming is noted during interglacials, a number of abrupt and short-lived temperature reversals are also observed within these intervals, such as during MIS 5a and MIS 5e. Overall, we find that MBT/CBT temperatures closely track changes in local summer insolation at 67°N, in agreement with numerous other proxy reconstructions from the lake (e.g. Melles et al., 2012). We note that before absolute temperatures can be reconstructed from Lake El'gygytgyn, a site-specific MBT/CBT calibration is required. We are currently investigating this by examining MBT/CBT in surface sediment and sediment trap samples from the lake. Overall, application of the MBT/CBT paleothermometer to Lake El'gygytgyn sediments appears to be a promising technique for generating a high-resolution Plio-Pleistocene continental temperature record from the western Arctic.

  7. The forcing of southwestern Asia teleconnections by low-frequency sea surface temperature variability during boreal winter

    USGS Publications Warehouse

    Hoell, Andrew; Funk, Christopher C.; Mathew Barlow

    2015-01-01

    Southwestern Asia, defined here as the domain bounded by 20°–40°N and 40°–70°E, which includes the nations of Iraq, Iran, Afghanistan, and Pakistan, is a water-stressed and semiarid region that receives roughly 75% of its annual rainfall during November–April. The November–April climate of southwestern Asia is strongly influenced by tropical Indo-Pacific variability on intraseasonal and interannual time scales, much of which can be attributed to sea surface temperature (SST) variations. The influences of lower-frequency SST variability on southwestern Asia climate during November–April Pacific decadal SST (PDSST) variability and the long-term trend in SST (LTSST) is examined. The U.S. Climate Variability and Predictability Program (CLIVAR) Drought Working Group forced global atmospheric climate models with PDSST and LTSST patterns, identified using empirical orthogonal functions, to show the steady atmospheric response to these modes of decadal to multidecadal SST variability. During November–April, LTSST forces an anticyclone over southwestern Asia, which results in reduced precipitation and increases in surface temperature. The precipitation and tropospheric circulation influences of LTSST are corroborated by independent observed precipitation and circulation datasets during 1901–2004. The decadal variations of southwestern Asia precipitation may be forced by PDSST variability, with two of the three models indicating that the cold phase of PDSST forces an anticyclone and precipitation reductions. However, there are intermodel circulation variations to PDSST that influence subregional precipitation patterns over the Middle East, southwestern Asia, and subtropical Asia. Changes in wintertime temperature and precipitation over southwestern Asia forced by LTSST and PDSST imply important changes to the land surface hydrology during the spring and summer.

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

    NASA Astrophysics Data System (ADS)

    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 < 0.05 except black locust) indicated that FBD is more 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.

  9. 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 < 0.05 except black locust) indicated that FBD is more 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

  10. 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.

  11. Temperature and precipitation in Northeast China during the last 150 years: relationship to large-scale climatic variability

    NASA Astrophysics Data System (ADS)

    Alessio, S.; Taricco, C.; Rubinetti, S.; Vivaldo, G.; Mancuso, S.

    2014-07-01

    The analysis of two historical time series of temperature and precipitation in Northeast China, spanning, respectively, 1870-2004 and 1841-2004, performed by continuous wavelet transform and other classical and advanced spectral methods, is presented here. Both variables show a particular trend and oscillations of about 85, 60, 35 and 20 years that are highly significant, with a phase opposition at the centennial scale and at the 20-year scale. The analysis of the four temperature series relative to single seasons shows that the 20-year cycle is typical of the summer monsoon season, while the 35-year cycle is most evident in winter. The cycles of ~ 60 years and longer are present in all seasons. The centennial variation of temperature and precipitation describes well the 1970-1980 transition between a period of relatively strong East Asian Summer Monsoon (EASM), corresponding to high precipitation and relatively cool temperatures in Northeast China, and a conditions of weak EASM (low precipitation and warm temperatures). The connection of the detected local variations with large-scale climatic variability is deduced from the comparison with different climatic records (Northern Hemisphere temperature, Pacific Decadal Oscillation and Atlantic Multidecadal Oscillation indexes).

  12. Coastal ocean climatology of temperature and salinity off the Southern California Bight: Seasonal variability, climate index correlation, and linear trend

    NASA Astrophysics Data System (ADS)

    Kim, Sung Yong; Cornuelle, Bruce D.

    2015-11-01

    A coastal ocean climatology of temperature and salinity in the Southern California Bight is estimated from conductivity-temperature-depth (CTD) and bottle sample profiles collected by historical California Cooperative Oceanic Fisheries Investigation (CalCOFI) cruises (1950-2009; quarterly after 1984) off southern California and quarterly/monthly nearshore CTD surveys (within 30 km from the coast except for the surfzone; 1999-2009) off San Diego and Los Angeles. As these fields are sampled regularly in space, but not in time, conventional Fourier analysis may not be possible. The time dependent temperature and salinity fields are modeled as linear combinations of an annual cycle and its five harmonics, as well as three standard climate indices (El Niňo-Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), North Pacific Gyre Oscillation (NPGO)), the Scripps Pier temperature time series, and a mean and linear trend without time lags. Since several of the predictor indices are correlated, the indices are successively orthogonalized to eliminate ambiguity in the identification of the contributed variance of each component. Regression coefficients are displayed in both vertical transects and horizontal maps to evaluate (1) whether the temporal and spatial scales of the two data sets of nearshore and offshore observations are consistent and (2) how oceanic variability at a regional scale is related to variability in the nearshore waters. The data-derived climatology can be used to identify anomalous events and atypical behaviors in regional-scale oceanic variability and to provide background ocean estimates for mapping or modeling.

  13. Temperature and precipitation drive temporal variability in aquatic carbon and GHG concentrations and fluxes in a peatland catchment.

    PubMed

    Dinsmore, K J; Billett, M F; Dyson, K E

    2013-07-01

    The aquatic pathway is increasingly being recognized as an important component of catchment carbon and greenhouse gas (GHG) budgets, particularly in peatland systems due to their large carbon store and strong hydrological connectivity. In this study, we present a complete 5-year data set of all aquatic carbon and GHG species from an ombrotrophic Scottish peatland. Measured species include particulate and dissolved forms of organic carbon (POC, DOC), dissolved inorganic carbon (DIC), CO2 , CH4 and N2 O. We show that short-term variability in concentrations exists across all species and this is strongly linked to discharge. Seasonal cyclicity was only evident in DOC, CO2 and CH4 concentration; however, temperature correlated with monthly means in all species except DIC. Although the temperature correlation with monthly DOC and POC concentrations appeared to be related to biological productivity in the terrestrial system, we suggest the temperature correlation with CO2 and CH4 was primarily due to in-stream temperature-dependent solubility. Interannual variability in total aquatic carbon concentration was strongly correlated with catchment gross primary productivity (GPP) indicating a strong potential terrestrial aquatic linkage. DOC represented the largest aquatic carbon flux term (19.3 ± 4.59 g C m(-2)  yr(-1) ), followed by CO2 evasion (10.0 g C m(-2)  yr(-1) ). Despite an estimated contribution to the total aquatic carbon flux of between 8 and 48%, evasion estimates had the greatest uncertainty. Interannual variability in total aquatic carbon export was low in comparison with variability in terrestrial biosphere-atmosphere exchange, and could be explained primarily by temperature and precipitation. Our results therefore suggest that climatic change is likely to have a significant impact on annual carbon losses through the aquatic pathway, and as such, aquatic exports are fundamental to the understanding of whole catchment responses to climate change. PMID:23568485

  14. Increased winter soil temperature variability enhances nitrogen cycling and soil biotic activity in temperate heathland and grassland mesocosms

    NASA Astrophysics Data System (ADS)

    Schuerings, J.; Jentsch, A.; Hammerl, V.; Lenz, K.; Henry, H. A. L.; Malyshev, A. V.; Kreyling, J.

    2014-12-01

    Winter air temperatures are projected to increase in the temperate zone, whereas snow cover is projected to decrease, leading to increased soil temperature variability, and potentially to changes in nutrient cycling. Here, we experimentally evaluated the effects of increased winter soil temperature variability on selected aspects of the N-cycle in mesocosms containing different plant community compositions. The experiment was replicated at two sites, a colder mountainous upland site with high snow accumulation and a warmer and drier lowland site. Increased soil temperature variability enhanced soil biotic activity for both sites during winter, as indicated by 35% higher nitrogen (N) availability in the soil solution, 40% higher belowground decomposition and a 25% increase in the potential activity of the enzyme cellobiohydrolase. The mobilization of N differed between sites, and the 15N signal in leaves was reduced by 31% in response to winter warming pulses, but only at the cold site, with significant reductions occurring for three of four tested plant species at this site. Furthermore, there was a trend of increased N leaching in response to the recurrent winter warming pulses. Overall, projected winter climate change in the temperate zone, with less snow and more variable soil temperatures, appears important for shifts in ecosystem functioning (i.e. nutrient cycling). While the effects of warming pulses on plant N mobilization did not differ among sites, reduced plant 15N incorporation at the colder temperate site suggests that frost damage may reduce plant N uptake in a warmer world, with important implications for nitrogen cycling and nitrogen losses from ecosystems.

  15. 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.

  16. 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.

  17. A comparison of surface air temperature variability in three 1000-Yr. coupled ocean-atmosphere model integrations

    SciTech Connect

    Stouffer, R.J.; Hegerl, G.; Tett, S.

    2000-02-01

    This study compares the variability of surface air temperature in three long coupled ocean-atmosphere general circulation model integrations. It is shown that the annual mean climatology of the surface air temperatures (SAT) in all three models is realistic and the linear trends over the 1,000-yr integrations are small over most areas of the globe. Second, although there are notable differences among the models, the models' SAT variability is fairly realistic on annual to decadal timescales, both in terms of the geographical distribution and of the global mean values. A notable exception is the poor simulation of observed tropical Pacific variability. In the HadCM2 model, the tropical variability is overestimated, while in the GFDL and HAM3L models, it is underestimated. Also, the ENSO-related spectral peak in the globally averaged observed SAT differs from that in any of the models. The relatively low resolution required to integrate models for long time periods inhibits the successful simulation of the variability in this region. On timescales longer than a few decades, the largest variance in the models is generally located near sea ice margins in high latitudes, which are also regions of deep oceanic convection and variability related to variations in the thermohaline circulation. However, the exact geographical location of these maxima varies from model to model. The preferred patterns of interdecadal variability that are common to all three coupled models can be isolated by computing empirical orthogonal functions (EOFs) of all model data simultaneously using the common EOF technique. A comparison of the variance each model associated with these common EOF patterns shows that the models generally agree on the most prominent patterns of variability. However, the amplitudes of the dominant models of variability differ to some extent between the models and between the models and observations. For example, two of the models have a mode with relatively large values of the same sign over most of the Northern Hemisphere midlatitudes. This mode has been shown to be relevant for the separation of the temperature response pattern due to sulfate aerosol forcing from the response to greenhouse gas forcing.

  18. Decadal variability of the Tropical Atlantic Ocean Surface Temperature in shipboard measurements and in a Global Ocean-Atmosphere model

    NASA Technical Reports Server (NTRS)

    Mehta, Vikram M.; Delworth, Thomas

    1995-01-01

    Sea surface temperature (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 Global Ocean Surface Temperature Atlas (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. The second type of variability is considerably weaker than the first. As in the GOSTA time series, the multidecadal variability in the GFDL SST time series has approximately opposite phases between the tropical North and South Atlantic Oceans. Empirical orthogonal function analyses of the tropical Atlantic SST anomalies revealed a north-south bipolar pattern as the dominant pattern of decadal variability. It is suggested that the bipolar pattern can be interpreted as decadal variability of the interhemispheric gradient of SST anomalies. The decadal and multidecadal timescale variability of the tropical Atlantic SST, both in the actual and in the GFDL model, stands out significantly above the background 'red noise' and is coherent within each of the time series, suggesting that specific sets of processes may be responsible for the choice of the decadal and multidecadal timescales. Finally, it must be emphasized that the GFDL coupled ocean-atmosphere model generates the decadal and multidecadal timescale variability without any externally applied force, solar or lunar, at those timescales.

  19. The spatial variability of coastal surface water temperature during upwelling. [in Lake Superior

    NASA Technical Reports Server (NTRS)

    Scarpace, F. L.; Green, T., III

    1979-01-01

    Thermal scanner imagery acquired during a field experiment designed to study an upwelling event in Lake Superior is investigated. Temperature data were measured by the thermal scanner, with a spatial resolution of 7 m. These data were correlated with temperatures measured from boats. One- and two-dimensional Fourier transforms of the data were calculated and temperature variances as a function of wavenumber were plotted. A k-to-the-minus-three dependence of the temperature variance on wavenumber was found in the wavenumber range of 1-25/km. At wavenumbers greater than 25/km, a k-to-the-minus-five-thirds dependence was found.

  20. Variable-temperature microcrystal X-ray diffraction studies of negative thermal expansion in the pure silica zeolite IFR.

    PubMed

    Villaescusa, L A; Lightfoot, P; Teat, S J; Morris, R E

    2001-06-13

    Variable-temperature single-crystal X-ray diffraction using a synchrotron X-ray source has allowed the mechanism of negative thermal expansion in the pure silica zeolite IFR to be studied in greater detail than was previously possible over the temperature range 30-557 K. The results have allowed the changes in average atomic position with temperature to be measured and the structural features that are important in negative thermal expansion to be identified. The structure of zeolite IFR can be split into two regions: columns of fused rings that expand with temperature and the intercolumn regions, which tend to contract on heating. These competing changes combine to produce a material that contracts parallel to the crystallographic a and b axes and expands in the c-direction. Correlations between zeolite structure and thermal expansivity are also reported. PMID:11389626

  1. A variable conductance gas switch for intermediate temperature operation of liquid He/liquid N2 cryostats

    NASA Technical Reports Server (NTRS)

    Rayner, J. T.; Chuter, T. C.; Mclean, I. S.; Radostitz, J. V.; Nolt, I. G.

    1988-01-01

    A technique for establishing a stable intermediate temperature stage in liquid He/liquid N2 double vessel cryostats is described. The tertiary cold stage, which can be tuned to any temperature between 10 and 60 K, is ideal for cooling IR sensors for use in astronomy and physics applications. The device is called a variable-conductance gas switch. It is essentially a small chamber, located between the cold stage and liquid helium cold-face, whose thermal conductance may be controlled by varying the pressure of helium gas within the chamber. A key feature of this device is the large range of temperature control achieved with a very small (less than 10 mW) heat input from the cryogenic temperature control switch.

  2. Exact solutions of laminar-boundary-layer equations with constant property values for porous wall with variable temperature

    NASA Technical Reports Server (NTRS)