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1

Day-to-day variations of temperature in Texas  

E-print Network

San Antonio 6. 2 Current 6 3 6 e 4 5a8 3a7 2 e8 le9 le4 lo5 2 o 2 3 o 4 5a3 5o5 5. 6 5, 2 4. 1 2. 7 1 ~ 7 1. 1 1, 4 1, 9 3, 1 5. 2 5. 2 Temperature. " The data for San Antonio were extracted from Henryrs (1906) work and represent, the I. V. of the mean... 4 e 4 4 e5 3 ' 9 3 o 3 Current. 4, 7 4, 4 4 o 6 3 ' 9 3 e 3 2 ' 5 2 o 3 2 e0 2 5 2 9 3 ' 8 4. 0 2 1 2, 6 1 8 2 2 2. 6 4. 1 3 ' 7 Galveston 5. 6 Current, 6, 0 4 e 6 3 ~ 8 2 e 2 lo8 le3 lel le4 le9 2 e 9 4a9 5e 2 4 e 7 3 e 6 2 e 4 le7 lo4 leO 1 ~ 5 1 ~ 6 3 o0 4 e 7 4 ' 8...

Breese, Richard Preston

1968-01-01

2

On the enigma of day-to-day variability in equatorial spread F  

NASA Astrophysics Data System (ADS)

We show that large-scale wave structure (LSWS), in plasma density in the bottomside F layer, is a hitherto unheralded contributor to the long-standing enigma of day-to-day variability in equatorial spread F (ESF). Little is known about LSWS; it seems to appear in altitude near a vertical shear in zonal plasma drift, during the post-sunset rise of the F layer, and its growth via an interchange instability appears to predispose quasi-periodically spaced regions to development of plasma bubbles. First indications are that LSWS development is necessary and sufficient for ESF occurrence. We suggest that variability in LSWS development, perhaps together with the shear in zonal drift, may contribute to day-to-day ESF variability. A need revealed by this study is that a cluster of distributed sensors, not isolated ones, is necessary to pursue the problem of day-to-day variability.

Tsunoda, Roland T.

2005-04-01

3

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

PubMed

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

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

4

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

PubMed

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

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

2015-02-01

5

Day-to-day variability of foEs in the equatorial ionosphere  

NASA Astrophysics Data System (ADS)

seasonal, and solar cycle effects of the variability (VR) of the critical frequency of sporadic E layer (foEsq) are investigated at Ibadan (7.4°N, 3.9°E, 6°S dip) in the African sector during high solar activity (HSA) year of 1958 (Rz = 181), moderate solar activity (MSA) year of 1973 (Rz = 30), and low solar activity (LSA) year of 1965 (Rz = 17). The diurnal variation of foEsq VR is characterized by post-midnight (32%-78%) and pre-midnight (20%-84%) peaks during high solar activity (HSA), the only epoch of the three showing these peaks and a diurnal trend. While the daytime foEsq VRs of the three epochs show no seasonal trend, pre-midnight and post-midnight, the foEsq VRs during HSA and LSA show seasonal trends. Similarity is observed in the curve of reciprocal of percentage occurrence of Esq and that of foEsq VR, indicating inverse variation of percentage occurrence and foEsq VR. Longitudinal influence is observed in the diurnal variation of HSA and MSA July foEsq VR of Ibadan (7.4°N, 3.9°E, 6°S dip) in the African sector, which is in the neighborhood of the Greenwich Meridian (GM); Singapore (1.3°N, 108.3°E, 17.6°S dip) in the Asian sector, east of GM; and Huancayo (12°S, 284.7°E, 1.90 dip) in the American sector, west of GM.

Somoye, E. O.; Akala, A. O.; Adeniji-Adele, R. A.; Onori, E. O.; Ogwala, A.; Karimu, A. O.

2013-09-01

6

NPR: Day to Day  

NSDL National Science Digital Library

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

7

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

NASA Astrophysics Data System (ADS)

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.

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

8

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

PubMed Central

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

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

2015-01-01

9

Day to day with COPD  

MedlinePLUS

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

10

Individual differences in the day-to-day variability of pain, fatigue, and well-being in patients with rheumatic disease: associations with psychological variables.  

PubMed

This report examines day-to-day variability in rheumatology patients' ratings of pain and related quality-of-life variables as well as predictors of that variability. Data from 2 studies were used. The hypothesis was that greater psychological distress (i.e., depression and anxiety) and poorer coping appraisals (i.e., higher pain catastrophizing and lower self-efficacy) are associated with more variability. Electronic daily diary ratings were collected from 106 patients from a community rheumatology practice across 28 days (study 1) and from 194 osteoarthritis patients across 7 days (study 2). In multilevel modeling analyses, substantial day-to-day variability was evident for all variables in both studies, and individual patients differed considerably and somewhat reliably in the magnitude of their variability. Higher levels of depression significantly predicted greater variability in pain, as well as in happiness and frustration (study 1). Lower self-efficacy was associated with more variability in patients' daily satisfaction with accomplishments and in the quality of their day (study 2). Greater pain catastrophizing and higher depression predicted more variability in interference with social relationships (study 2). Anxiety was not significantly associated with day-to-day variability. The results of these studies suggest that individual differences in the magnitude of symptom fluctuation may play a vital role in understanding patients' adjustment to pain. Future research will be needed to examine the clinical utility of measuring variability in patients' pain and well-being, and to understand whether reducing variability may be an important treatment target. PMID:22349917

Schneider, Stefan; Junghaenel, Doerte U; Keefe, Francis J; Schwartz, Joseph E; Stone, Arthur A; Broderick, Joan E

2012-04-01

11

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

NASA Astrophysics Data System (ADS)

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

Fagundes, P. R.

2013-12-01

12

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)

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.

Etoundi Messanga, Honoré

2015-04-01

13

Characteristics of the equatorial ionization anomaly in relation to the day-to-day variability of ionospheric irregularities around the postsunset period  

Microsoft Academic Search

The equatorial ionosphere is characterized by the equatorial ionization anomaly (EIA) over a major part of the day, and ionospheric F region irregularities causing amplitude and phase scintillations on transionospheric satellite links during the postsunset period. Scintillations of transionospheric signals constitute one of the most intense Space Weather related propagation effects and exhibit extreme variability in space and time. The

A. Paul; A. DasGupta

2010-01-01

14

An attempt to establish a statistical model of the day-to-day variability of the NmF2 and hmF2 parameters computed from IRI  

NASA Astrophysics Data System (ADS)

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 NmF2 and hmF2 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) NmF2 at noontime: ±10% to ±30% with maxima over the northern and southern peaks of the Equatorial Anomaly; (ii) NmF2 at midnight: ±20% to ±45%, with the greatest values in the equatorial region during the months of May and September; (iii) hmF2 at noontime: ±2% to ±10% with minima over the modip equator; and (iv) hmF2 at midnight: ±3% to ±11% with the greatest values in the equatorial region from January to May and from September to January.

Brunini, Claudio; Azpilicueta, Francisco; Janches, Diego

2015-04-01

15

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

ERIC Educational Resources Information Center

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…

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

2013-01-01

16

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

PubMed

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

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

2015-02-01

17

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

ERIC Educational Resources Information Center

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…

Welch, Alicia J.

18

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

ERIC Educational Resources Information Center

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…

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

2007-01-01

19

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

ERIC Educational Resources Information Center

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

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

2008-01-01

20

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

E-print Network

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

Peeta, Srinivas

21

Being at-risk or taking risks? Day-to-day experiences of electricity blackouts  

Microsoft Academic Search

During recent years, the risks of critical infrastructures failing have been in the foreground in many European and EU policies. This paper presents another viewpoint to these discussions: the day-to-day user experiences of actual failures. By presenting research findings from a study done of electricity blackouts in Finland, I aim to show that failures are complicated situations and people hardly

Antti Silvast

2008-01-01

22

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

NASA Astrophysics Data System (ADS)

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.

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

2014-07-01

23

Day-to-day variability of the E layer Luke Moore,1  

E-print Network

in the E layer, a one-dimensional time-dependent photochemical model of the Earth's upper atmosphere of the E layer, J. Geophys. Res., 111, A06307, doi:10.1029/2005JA011448. 1. Introduction [2] The Earth of the Earth's primary photochemical ionospheric layer in detail is beneficial to the study of other

Mendillo, Michael

24

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

NASA Technical Reports Server (NTRS)

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.

Nowlis, D. P.

1972-01-01

25

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

PubMed

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

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

2014-01-01

26

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

PubMed Central

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

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

2014-01-01

27

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

PubMed

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

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

28

Common orthopaedic problems in day to day general practice (in economically handicapped community).  

PubMed

The object for writing this article is to summarise different common orthopaedic problems for which common people of our country, economically handicapped, come to the general practitioners in their day to day practice. 'Pain' is the main ailment whatever may be the cause. Where pain killer is not the answer, it is to aware the general practitioner to find out what is behind the pain. A ready reference knowledge for that condition with its available treatment modalities is essential for the doctor and the patient. Deformities and other complaints are mentioned after the pain. An attempt has been made to classify the causes and in short the treatment modalities according to the disease and site to be addressed. Influence of information media on public opinion for decision making has gained momentum. To gain more knowledge, the general practitioners, who are the pillars, the pillars of national health, should study a little more in detail the Journal of Indian Medical Association (JIMA), available textbooks or other journals to have a first hand knowledge to tackle orthopaedic cases. PMID:17915795

Bhattacharya, S; Chatterjee, Pratyush; Dutta, Sumon

2007-05-01

29

Statistical modeling for the mitigation of GPS multipath delays from day-to-day range measurements  

NASA Astrophysics Data System (ADS)

Based on a least-squares model for double-difference GPS pseudoranges and carrier-phases, measurement residuals expressed in time series during an observation session are positively correlated between one sidereal day and the preceding days. As a result of the satellite’s period, the phenomenon, which takes place at a user receiving site, is attributed to multipath interference. Examples from a weekly measurement dataset of control baselines are shown, where the known end-point coordinates also serve as a benchmark for assessing positioning accuracy. The system of error equations for mixed-model adjustment is divided into two subsystems. One set of the error equations is related to the real range measurements, while the other involves the pseudo-observation with an empirical sample variance. According to the existing correlation between day-to-day residual estimates, a multipath-mitigating algorithm is proven to improve the accuracy of the GPS height determination by at least 40%. It is also found that the algorithm depends on a variance-component estimator that adaptively scales an error covariance matrix for both the real range and empirical delay measurements.

Wu, Joz; Hsieh, Chi-Hsiu

2010-04-01

30

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

PubMed Central

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

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

2014-01-01

31

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

PubMed Central

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

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

2011-01-01

32

Day-to-day changes in oxygen uptake kinetics at the onset of exercise during strenuous endurance training  

Microsoft Academic Search

Summary  The aim of this study was to assess the effect of strenuous endurance training on day-to-day changes in oxygen uptake (VO2) on-kinetics (time constant) at the onset.of exercise. Four healthy men participated in strenuous training, for 30 min·day–1, 6 days·week–1 for 3 weeks. The VO2 was measured breath-by-breath every day except Sunday at exercise intensities corresponding to the lactate threshold

Takayoshi Yoshida; Masao Udo; Takashi Ohmori; Yojiro Matsumoto; Takashi Uramoto; Koji Yamamoto

1992-01-01

33

Day to Day  

ERIC Educational Resources Information Center

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…

Jurecki, Dennis

2006-01-01

34

Day-to-day measurement of patient-reported outcomes in exacerbations of chronic obstructive pulmonary disease  

PubMed Central

Background Exacerbations of chronic obstructive pulmonary disease (COPD) are a major burden to patients and to society. Little is known about the possible role of day-to-day patient-reported outcomes during an exacerbation. This study aims to describe the day-to-day course of patient-reported health status during exacerbations of COPD and to assess its value in predicting clinical outcomes. Methods Data from two randomized controlled COPD exacerbation trials (n = 210 and n = 45 patients) were used to describe both the feasibility of daily collection of and the day-to-day course of patient-reported outcomes during outpatient treatment or admission to hospital. In addition to clinical parameters, the BORG dyspnea score, the Clinical COPD Questionnaire (CCQ), and the St George’s Respiratory Questionnaire were used in Cox regression models to predict treatment failure, time to next exacerbation, and mortality in the hospital study. Results All patient-reported outcomes showed a distinct pattern of improvement. In the multivariate models, absence of improvement in CCQ symptom score and impaired lung function were independent predictors of treatment failure. Health status and gender predicted time to next exacerbation. Five-year mortality was predicted by age, forced expiratory flow in one second % predicted, smoking status, and CCQ score. In outpatient management of exacerbations, health status was found to be less impaired than in hospitalized patients, while the rate and pattern of recovery was remarkably similar. Conclusion Daily health status measurements were found to predict treatment failure, which could help decision-making for patients hospitalized due to an exacerbation of COPD. PMID:23766644

Kocks, Jan Willem H; van den Berg, Jan Willem K; Kerstjens, Huib AM; Uil, Steven M; Vonk, Judith M; de Jong, Ynze P; Tsiligianni, Ioanna G; van der Molen, Thys

2013-01-01

35

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

PubMed Central

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

Hughes, John R.

2009-01-01

36

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

PubMed Central

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

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

2014-01-01

37

Day-to-Day Travel-Time Trends and Travel-Time Prediction from Loop-Detector Data  

Microsoft Academic Search

This paper presents an approach to estimate future travel times on a freeway using flow and occupancy data from single loop detectors and historical travel time information. The work uses linear regression with stepwise variable selection method and more advanced tree based methods. The analysis considers forecasts ranging from a few minutes into the future up to an hour ahead.

Jaimyoung Kwon; Benjamin Coifman; Peter Bickel

2000-01-01

38

Changes in Student Teachers' Agency Beliefs during a Teacher Education Year, and Relationships with Observed Classroom Quality, and Day-to-Day Experiences  

ERIC Educational Resources Information Center

Background: Conceptualizations of teachers' agency beliefs converge around domains of support and instruction. Aim: We investigated changes in student teachers' agency beliefs during a 1 year teacher education course, and related these to observed classroom quality and day-to-day experiences in partnership schools during the practicum. Samples:…

Malmberg, Lars-Erik; Hagger, Hazel

2009-01-01

39

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

ERIC Educational Resources Information Center

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…

Altermatt, Ellen Rydell

2015-01-01

40

Relevance of correction for drift and day-to-day variation in cystatin C measurement: a post-hoc analysis of the PREVEND cohort, with independent replication in the ESTHER cohort.  

PubMed

Abstract Background: Despite standard laboratory quality control, drift and day-to-day variability in cystatin C measurements can be observed. We investigated whether correction for drift and day-to-day variation in cystatin C measurements improves the association of estimated glomerular filtration rate (eGFR) with chronic kidney disease (CKD) risk factors and prognosis. Methods: Plasma samples of the PREVEND study (Dutch cohort study, n=8592) were used to measure cystatin C (Gentian assay) on 243 random days. A correction factor was calculated for each measurement day. GFR was estimated with CKD-EPI equation using routinely measured cystatin C (eGFRcysC) and corrected cystatin C (eGFRcysC corr). Participants were categorized in six categories of eGFRcysC and eGFRcysC corr: ?120, 90-119, 75-89, 60-74, 45-59 and <45 mL/min/1.73m2. Independent replication was performed in the ESTHER study (German cohort study, n=9949). Results: Compared to non-reclassified participants, participants re-classified upward had significantly lower age, body mass index, blood pressure, cholesterol, glucose and albuminuria, whereas the opposite was true for participants reclassified downward. CKD risk factors explained more variance in eGFRcysC corr than in eGFRcysC (p<0.001). Compared to non-reclassified participants, risk of incident cardiovascular events (n=789, follow-up 9.3±2.7 years) tended to be higher in downward reclassified and lower in upward reclassified participants. Net reclassification improvement for incident cardiovascular events using eGFRcysC corr was positive (0.102, p=0.019). The ESTHER study showed similar results. Conclusions: Correction for drift and day-to-day variation in cystatin C measurement improves eGFR using cystatin C for its association with CKD risk factors and incident cardiovascular events. PMID:25415637

Vart, Priya; Bakker, Stephan J L; Schöttker, Ben; de Zeeuw, Dick; Rothenbacher, Dietrich; Brenner, Hermann; Heerspink, Hiddo J Lambers; Saum, Kai-Uwe; Reijneveld, Sijmen A; Bültmann, Ute; Koenig, Wolfgang; Gansevoort, Ron T

2014-11-21

41

Vacuum Variable Medium Temperature Blackbody  

NASA Astrophysics Data System (ADS)

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.

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

2010-09-01

42

[The day-to-day routine in hospitals--standards and conflicts, based on the example of the Rothschild spital in Vienna around the year 1900].  

PubMed

The juxtaposition of official regulations and letters of complaint from Vienna's Rothschild Hospital shows, beyond the rhetoric and euphemisms of hospital reports, how lively and diverse day-to-day life was in a Jewish hospital around the year 1900. The letters of complaint query the official hospital rules and show that ideal and reality did not always coincide. Often, religious questions were at the root of the critique--such as doubts as to whether kosher dietary laws were adhered to--or conflicts between the agents involved, be they individuals or groups, patients, nurses, physicians or administrative staff. As part of this process, power structures, social hierarchies, patient rights and gender issues were called into question and renegotiated. PMID:25134251

Malleier, Elisabeth

2014-01-01

43

Diagnostic Performance of Schistosoma Real-Time PCR in Urine Samples from Kenyan Children Infected with Schistosoma haematobium: Day-to-day Variation and Follow-up after Praziquantel Treatment  

PubMed Central

Background In an effort to enhance accuracy of diagnosis of Schistosoma haematobium, this study explores day-to-day variability and diagnostic performance of real-time PCR for detection and quantification of Schistosoma DNA compared to other diagnostic tools in an endemic area before and after treatment. Methodology Previously collected urine samples (N?=?390) from 114 preselected proven parasitological and/or clinical S. haematobium positive Kenyan schoolchildren were analyzed by a Schistosoma internal transcribed spacer-based real-time PCR after 14 years of storage. Pre-treatment day-to-day fluctuations of PCR and microscopy over three consecutive days were measured for 24 children using intra-class correlation coefficient. A combined ‘gold standard’ (PCR and/or microscopy positive) was used to measure sensitivity and negative predictive value (NPV) of several diagnostic tools at baseline, two and 18 months post-treatment with praziquantel. Principal Findings All 24 repeatedly tested children were PCR-positive over three days with little daily variation in median Ct-values, while 83.3% were found to be egg-positive for S. haematobium at day 1 and 75.0% at day 2 and 3 pre-treatment, signifying daily fluctuations in microscopy diagnosis. Of all 114 preselected schoolchildren, repeated microscopic measurements were required to detect 96.5% versus 100% of positive pre-treatment cases by single PCR. At two months post-treatment, microscopy and PCR detected 22.8% versus 69.3% positive children, respectively. Based on the ‘gold standard’, PCR showed high sensitivity (>92%) as compared to >31% sensitivity for microscopy, both pre- and post-treatment. Conclusions/Significance Detection and quantification of Schistosoma DNA in urine by real-time PCR was shown to be a powerful and specific diagnostic tool for detection of S. haematobium infections, with less day-to-day variation and higher sensitivity compared to microscopy. The superior performance of PCR before, and two and 18 months post-treatment provides a compelling argument for PCR as an accurate and reproducible tool for monitoring treatment efficacy. PMID:24743389

Vinkeles Melchers, Natalie V. S.; van Dam, Govert J.; Shaproski, David; Kahama, Anthony I.; Brienen, Eric A. T.; Vennervald, Birgitte J.; van Lieshout, Lisette

2014-01-01

44

Elucidating satisfaction with physical activity: an examination of the day-to-day associations between experiences with physical activity and satisfaction during physical activity initiation.  

PubMed

Satisfaction with physical activity is known to be an important factor in physical activity maintenance, but the factors that influence satisfaction are not well understood. The purpose of this study was to elucidate how ongoing experiences with recently initiated physical activity are associated with satisfaction. Participants (n?=?116) included insufficiently active volunteers who initiated a self-directed physical activity regimen and completed daily diaries about their experiences for 28?days. We used multilevel models to examine the associations between experiences with physical activity and satisfaction. Significant between-person effects demonstrated that people reporting higher average levels of positive experiences and lower levels of thinking about the negative aspects of exercise were more likely to report higher levels of satisfaction (ps?day-to-day fluctuations in these experiences were associated with changes in satisfaction. These findings elucidate a process through which people may determine their satisfaction with physical activity. PMID:23909464

Baldwin, Austin S; Baldwin, Scott A; Loehr, Valerie G; Kangas, Julie L; Frierson, Georita M

2013-01-01

45

Seasonal Variability in OH Mesospheric Temperatures at Low-Latitudes and Comparison with Timed-Saber Temperatures  

NASA Astrophysics Data System (ADS)

The Utah State University Mesospheric Temperature Mapper (MTM) is a high performance, solid state imaging system capable of determining variations in the rotational temperatures of two upper mesospheric near infrared nightglow emissions: the OH (6,2) Meinel band (peak altitude 87 km) and the O2(0,1) Atmospheric band emission (peak altitude 94 km), with a precision of typically 1-2K in 3 min. For the past 5 years (November 201-December 2006), the MTM was operated near-continuously from the Air Force AMOS Facility, near the summit of Haleakala Crater, Maui, HI (24.8 N, 204 E), 2970 m). Autonomous observations were made as part of the Maui-MALT program which is a joint initiative between the National Science Foundation (NSF) and the US Air Force Office of Scientific research (AFOSR) to investigate the dynamics of the upper atmosphere in unprecedented detail. Over 1000 nights of high-quality data have been obtained, providing novel information on the nocturnal behavior of mesospheric temperature and its variability enabling a detailed comparative study with TIMED-SABER temperature measurements at low-latitudes. Here we focus on a seasonal comparison with MTM OH temperatures. The variability of the MTM and SABER temperatures track well on day-to-day and seasonal time scales giving high confidence in the compatibility of the two data sets. However, there appears to be a 5 K systematic offset between these data with the MTM temperatures warmer. A similar offset has been observed at mid-latitudes and this new study extends this comparison to lower latitudes where non-LTE effects are not significant. The origin and variability in this offset will be investigated as a function of season.

Taylor, Michael J.; Zhao, Yucheng; Russell, J. M., III

46

A Peltier-based variable temperature source  

NASA Astrophysics Data System (ADS)

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

Molki, Arman; Roof Baba, Abdul

2014-11-01

47

Temperature variability in lake sediments  

Microsoft Academic Search

Sediment temperatures were simulated from the sediment-water interface down to 10 m for circular lakes with surface areas of 0.2-10km2 and maximum lake depths of 4-24 m. The calculations were made using daily weather conditions measured over 19 years (1961-1979) at three geographic locations, representing climate conditions from north to south latitudes in the central United States. A one-dimensional sediment

Xing Fang; Heinz G. Stefan

1998-01-01

48

Temperature variability in lake sediments  

Microsoft Academic Search

Sediment temperatures were simulated from the sediment-water interface down to 10 m for circular lakes with surface areas of 0.2–10 km2 and maximum lake depths of 4–24 m. The calculations were made using daily weather conditions measured over 19 years (1961–1979) at three geographic locations, representing climate conditions from north to south latitudes in the central United States. A one-dimensional

Xing Fang; Heinz G. Stefan

1998-01-01

49

Variable temperature semiconductor film deposition  

DOEpatents

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.

Li, X.; Sheldon, P.

1998-01-27

50

THE MULTI-USE STEINEL VARIABLE TEMPERATURE  

E-print Network

indoors. When servicing, use only identical replacement parts. When using electric tools, basic safety equipment Specifications Temperature Variable from 212° F to 1100° F Watts 1500W Weight 1.5 lbs. Supply

Kleinfeld, David

51

1 O sing unto the | Lord a new | song : sing unto the | Lord | all the whole | earth. 2 Sing unto the | Lord and praise his | Name : be telling of his sal | vation from | day to | day.  

E-print Network

Psalm 96 1 O sing unto the | Lord a · new | song : sing unto the | Lord | all the · whole | earth. 2 Sing unto the | Lord and · praise his | Name : be telling of his sal | vation · from | day to | day. 3 Declare his | honour · unto the | heathen : and his | wonders · unto | all | people. 4

Lasenby, Joan

52

Variable temperature seat climate control system  

DOEpatents

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.

Karunasiri, Tissa R. (Van Nuys, CA); Gallup, David F. (Pasadena, CA); Noles, David R. (Glendale, CA); Gregory, Christian T. (Alhambra, CA)

1997-05-06

53

Day-to-Day Fluctuations in Mars' Total Electron Content: Implications for Navigation and Position Fixing on Future Missions to Mars.  

NASA Astrophysics Data System (ADS)

The Mars Global Surveyor (MGS) radio science experiment has provided the first opportunity to observe martian electron density vs. altitude profiles, Ne(h), on consecutive days. The integral with height of Ne(h) defines the total electron content (TEC) of the ionosphere, a parameter widely used on Earth for geophysical studies. Values of TEC also impose a fundamental limitation on the accuracy of terrestrial navigation and geo-location systems, such as the much-used Global Positioning System (GPS). We have analyzed two sets of MGS ionospheric data (December 1998 and March 1999) to characterize the variability of TEC with the goal of defining possible "space weather" effects on Mars. Computer simulations have been used to characterize the range of magnitudes such TEC-induced fluctuations might pose to GPS-like systems used in future Mars exploration.

Smith, S. M.; Martinis, C. R.; Mendillo, M.; Hinson, D. P.; Pi, X.

2001-12-01

54

Variable effects of temperature on insect herbivory  

PubMed Central

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

Burkepile, Deron E.; Parker, John D.

2014-01-01

55

Isotopes in day to day life  

NASA Astrophysics Data System (ADS)

Developments are reported in the use of isotopic labeling and isotope irradiation in agriculture, medical science, hydrology, geochemistry, geophysics, environment pollution detection, and industries. Radioisotope instruments are described as well as techniques for gamma radiography, neutron radiography, and autoradiography. Isotope dating in geology and archaeology is covered. Basic scientific research topics in various areas are listed.

1984-06-01

56

Compact variable-temperature scanning force microscope.  

PubMed

A compact design for a cryogenic variable-temperature scanning force microscope using a fiber-optic interferometer to measure cantilever deflection is presented. The tip-sample coarse approach and the lateral tip positioning are performed by piezoelectric positioners in situ. The microscope has been operated at temperatures between 6 and 300 K. It is designed to fit into an 8 T superconducting magnet with the field applied in the out-of-plane direction. The results of scanning in various modes are demonstrated, showing contrast based on magnetic field gradients or surface potentials. PMID:17552828

Chuang, Tien-Ming; de Lozanne, Alex

2007-05-01

57

Forecasting neutron star temperatures: predictability and variability.  

PubMed

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

Page, Dany; Reddy, Sanjay

2013-12-13

58

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

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

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

2013-01-01

59

Predation Life History Responses to Increased Temperature Variability  

PubMed Central

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

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

2014-01-01

60

Variable Temperature Equipment for a Commercial Magnetic Susceptibility Balance  

ERIC Educational Resources Information Center

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…

Lotz, Albert

2008-01-01

61

Contribution of solar radiation to decadal temperature variability over land  

PubMed Central

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

Wang, Kaicun; Dickinson, Robert E.

2013-01-01

62

Variable temperature electrochemical strain microscopy of Sm-doped ceria  

SciTech Connect

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

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

2013-01-01

63

Influence of modes of climate variability on global temperature extremes  

Microsoft Academic Search

The influence of large-scale modes of climate variability on worldwide summer and winter temperature extremes has been analyzed, namely, that of the El Niño-Southern Oscillation, the North Atlantic Oscil- lation, and Pacific interdecadal climate variability. Monthly indexes for temperature extremes from world- wide land areas are used describe moderate extremes, such as the number of exceedences of the 90th and

Jesse Kenyon; Gabriele C. Hegerl

2007-01-01

64

On forced temperature changes, internal variability, and the AMO  

NASA Astrophysics Data System (ADS)

We estimate the low-frequency internal variability of Northern Hemisphere (NH) mean temperature using observed temperature variations, which include both forced and internal variability components, and several alternative model simulations of the (natural + anthropogenic) forced component alone. We then generate an ensemble of alternative historical temperature histories based on the statistics of the estimated internal variability. Using this ensemble, we show, first, that recent NH mean temperatures fall within the range of expected multidecadal variability. Using the synthetic temperature histories, we also show that certain procedures used in past studies to estimate internal variability, and in particular, an internal multidecadal oscillation termed the "Atlantic Multidecadal Oscillation" or "AMO", fail to isolate the true internal variability when it is a priori known. Such procedures yield an AMO signal with an inflated amplitude and biased phase, attributing some of the recent NH mean temperature rise to the AMO. The true AMO signal, instead, appears likely to have been in a cooling phase in recent decades, offsetting some of the anthropogenic warming. Claims of multidecadal "stadium wave" patterns of variation across multiple climate indices are also shown to likely be an artifact of this flawed procedure for isolating putative climate oscillations.

Mann, Michael E.; Steinman, Byron A.; Miller, Sonya K.

2014-05-01

65

Is obesity associated with lower body temperatures? Core temperature: a forgotten variable in energy balance  

E-print Network

Is obesity associated with lower body temperatures? Core temperature: a forgotten variable Northwestern University Comprehensive Center on Obesity, Chicago, IL 60611, USA Northwestern University in obesity, along with the associated adverse health consequences, has heightened interest in the fundamental

Linsenmeier, Robert

66

On the variability of seasonal temperature in southern South America  

NASA Astrophysics Data System (ADS)

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.

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

2013-04-01

67

Foliar respiration acclimation to temperature and temperature variable Q10 alter ecosystem carbon balance  

E-print Network

Foliar respiration acclimation to temperature and temperature variable Q10 alter ecosystem carbon Station, TX 77843-2135, USA Abstract The response of respiration to temperature in plants can described by a constant Q10 of respiration, and longer-term responses often include acclimation. Despite

Minnesota, University of

68

Variability in Measured Space Temperatures in 60 Homes  

SciTech Connect

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.

Roberts, D.; Lay, K.

2013-03-01

69

Joint variability of global runoff and global sea surface temperatures  

USGS Publications Warehouse

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.

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

2008-01-01

70

Orthogonal Wavelet Analysis: Interannual Variability in the Sea Surface Temperature  

Microsoft Academic Search

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

Mankin Mak

1995-01-01

71

Enhanced temperature variability in high-altitude climate change  

NASA Astrophysics Data System (ADS)

In the present article, monthly mean temperature at 56 stations assembled in 18 regional groups in 10 major mountain ranges of the world were investigated. The periods of the analysis covered the last 50 to 110 years. The author found that the variability of temperature in climatic time scale tends to increase with altitude in about 65 % of the regional groups. A smaller number of groups, 20 %, showed the fastest change at an intermediate altitude between the peaks (or ridges) and their foot, while the remaining small number of sites, 15 %, showed the largest trends at the foot of mountains. This tendency provides a useful base for considering and planning the climate impact evaluations. The reason for the amplification of temperature variation at high altitudes is traced back to the increasing diabatic processes in the mid- and high troposphere as a result of the cloud condensation. This situation results from the fact that the radiation balance at the earth's surface is transformed more efficiently into latent heat of evaporation rather than sensible heat, the ratio between them being 4 to 1. Variation in the surface evaporation is converted into heat upon condensation into cloud particles and ice crystals in the mid- and high troposphere. Therefore, this is the altitude where the result of the surface radiation change is effectively transferred. Further, the low temperature of the environment amplifies the effect of the energy balance variation on the surface temperature, as a result of the functional shape of Stefan-Boltzmann law. These processes altogether contribute to enhancing temperature variability at high altitudes. The altitude play s an important role in determining the temperature variability, besides other important factors such as topography, surface characteristics, cryosphere/temperature feedback and the frequency and intensity of an inversion. These processes have a profound effect not only on the ecosystem but also on glaciers and permafrost.

Ohmura, Atsumu

2012-12-01

72

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

SciTech Connect

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.

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

2012-08-01

73

Analysis and interpretation of variabilities in ozone and temperature fields  

NASA Technical Reports Server (NTRS)

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

Chandra, S.

1990-01-01

74

Inter-hemispheric temperature variability over the past millennium  

NASA Astrophysics Data System (ADS)

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.

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

75

Variable-temperature electron spin resonance of turquoise  

Microsoft Academic Search

The ESR spectra of several turquoise specimens contained an anisotropic component which was due to Cu2+ and an isotropic component arising from Fes+ ions. The Fe\\/Cu concentra- tion ratio obtained from these measurements agreed with ratios obtained analytically. A variable-temperature study from 77 K to 560 K indicated that the cupric ions are para- magnetic while the ferric ions behave

O. Cr-eRr; A. FnnacH

76

Water temperature variability within an Arctic stream; analysis and implications  

NASA Astrophysics Data System (ADS)

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.

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

2009-04-01

77

Historical Temperature Variability Affects Coral Response to Heat Stress  

PubMed Central

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

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

2012-01-01

78

Trends and variability in East African rainfall and temperature observations  

NASA Astrophysics Data System (ADS)

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).

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

2014-05-01

79

Infrared-temperature variability in a large agricultural field  

NASA Technical Reports Server (NTRS)

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.

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

1981-01-01

80

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

NASA Astrophysics Data System (ADS)

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.

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

2015-04-01

81

Global climate models’ bias in surface temperature trends and variability  

NASA Astrophysics Data System (ADS)

The Earth has warmed in the last century with the most rapid warming occurring near the surface in the Arctic. This Arctic amplification occurs partly because the extra heat is trapped in a thin layer of air near the surface due to the persistent stable-stratification found in this region. The amount of warming depends upon the extent of turbulent mixing in the atmosphere, which is described by the depth of the atmospheric boundary layer (ABL). Global climate models (GCMs) tend to over-estimate the depth of stably-stratified ABLs, and here we show that GCM biases in the ABL depth are strongly correlated with biases in the surface temperature variability. This highlights the need for a better description of the stably-stratified ABL in GCMs in order to constrain the current uncertainty in climate variability and projections of climate change in the surface layer.

Davy, Richard; Esau, Igor

2014-11-01

82

Electrical measurements of AC losses in high temperature superconducting coils at variable temperatures  

NASA Astrophysics Data System (ADS)

Measurements of AC losses in high temperature superconducting (HTS) coils wound from two different types of YBa2Cu3O7 (YBCO) coated conductors are reported. AC loss measurements by different arrangements of voltage loops and pick-up coils were investigated to propose accurate and convenient techniques to measure the AC losses in HTS coils, especially for large coils with the measurement signals significantly higher than the input range of typical lock-in amplifiers. A new and simple sub-cooling technique with an open liquid nitrogen bath was developed to measure AC losses in the sample coils at variable temperatures between 65 and 77 K. The temperature dependence of the losses in these coils was qualitatively explained based on the data on transport and magnetization AC losses in isolated tapes at variable temperatures.

Nguyen, D. N.; Kim, C. H.; Kim, J. H.; Pamidi, S.; Ashworth, S. P.

2013-09-01

83

Predicting Germination Response to Temperature. III. Model Validation Under Field-variable Temperature Conditions  

PubMed Central

•Background and Aims Two previous papers in this series evaluated model fit of eight thermal-germination models parameterized from constant-temperature germination data. The previous studies determined that model formulations with the fewest shape assumptions provided the best estimates of both germination rate and germination time. The purpose of this latest study was to evaluate the accuracy and efficiency of these same models in predicting germination time and relative seedlot performance under field-variable temperature scenarios. •Methods The seeds of four rangeland grass species were germinated under 104 variable-temperature treatments simulating six planting dates at three field sites in south-western Idaho. Measured and estimated germination times for all subpopulations were compared for all models, species and temperature treatments. •Key Results All models showed similar, and relatively high, predictive accuracy for field-temperature simulations except for the iterative-probit-optimization (IPO) model, which exhibited systematic errors as a function of subpopulation. Highest efficiency was obtained with the statistical-gridding (SG) model, which could be directly parameterized by measured subpopulation rate data. Relative seedlot response predicted by thermal time coefficients was somewhat different from that estimated from mean field-variable temperature response as a function of subpopulation. •Conclusions All germination response models tested performed relatively well in estimating field-variable temperature response. IPO caused systematic errors in predictions of germination time, and may have degraded the physiological relevance of resultant cardinal-temperature parameters. Comparative indices based on expected field performance may be more ecologically relevant than indices derived from a broader range of potential thermal conditions. PMID:16870642

HARDEGREE, STUART P.

2006-01-01

84

Optimizing the Day to Day Operation of Utility Systems  

E-print Network

in efficiency and eliminating steam injection into the gas turbine. The fact that the optimizer can consider all aspects of the utility system operation simultaneously demonstrates the power of the tool. In all utility systems, nothing stands still for long... item such as a pump or compressor is often left to the process operators without considering the overall impact on the site utility system. What is needed is a tool which considers the system efficiency on a site-wide basis and that is exactly what...

Eastwood, A.; Bealing, C.

85

Variability of Winter Air Temperature in Mid-Latitude Europe  

NASA Technical Reports Server (NTRS)

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.

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

2002-01-01

86

Cryptic impacts of temperature variability on amphibian immune function.  

PubMed

Ectothermic species living in temperate regions can experience rapid and potentially stressful changes in body temperature driven by abrupt weather changes. Yet, among amphibians, the physiological impacts of short-term temperature variation are largely unknown. Using an ex situ population of Cryptobranchus alleganiensis, an aquatic North American salamander, we tested the hypothesis that naturally occurring periods of temperature variation negatively impact amphibian health, either through direct effects on immune function or by increasing physiological stress. We exposed captive salamanders to repeated cycles of temperature fluctuations recorded in the population's natal stream and evaluated behavioral and physiological responses, including plasma complement activity (i.e. bacteria killing) against Pseudomonas aeruginosa, Escherichia coli and Aeromonas hydrophila. The best-fit model (?AICc=0, wi=0.9992) revealed 70% greater P. aeruginosa killing after exposure to variable temperatures and no evidence of thermal acclimation. The same model predicted 50% increased E. coli killing, but had weaker support (?AICc=1.8, wi=0.2882). In contrast, plasma defenses were ineffective against A. hydrophila, and other health indicators (leukocyte ratios, growth rates and behavioral patterns) were maintained at baseline values. Our data suggest that amphibians can tolerate, and even benefit from, natural patterns of rapid warming/cooling. Specifically, temperature variation can elicit increased activity of the innate immune system. This immune response may be adaptive in an unpredictable environment, and is undetectable by conventional health indicators (and hence considered cryptic). Our findings highlight the need to consider naturalistic patterns of temperature variation when predicting species' susceptibility to climate change. PMID:23948472

Terrell, Kimberly A; Quintero, Richard P; Murray, Suzan; Kleopfer, John D; Murphy, James B; Evans, Matthew J; Nissen, Bradley D; Gratwicke, Brian

2013-11-15

87

Complexation of Plutonium (IV) With Sulfate At Variable Temperatures  

SciTech Connect

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.

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

2006-10-05

88

Temperature-rate profiles by polarimetric variable-temperature kinetic experiments to study racemization reactions  

Microsoft Academic Search

The racemization of (?)-adrenaline was followed by polarimetric variable-temperature kinetic experiments obtaining activation parameters and kobs(T) profile in one tenth of the time usually spent for traditional kinetic runs. A polarimeter connected to a computer for the acquisition and processing of the analytical data was used. The kinetic profiles were processed by both an integral method and a differential method.

Giuseppe Alibrandi; Salvatore Coppolino; Santi D'Aliberti; Paola Ficarra; Norberto Micali; Antonino Villari

2002-01-01

89

Linking global climate and temperature variability to widespread amphibian declines putatively caused  

E-print Network

Linking global climate and temperature variability to widespread amphibian declines putatively that the proposed link be- tween climate change and widespread amphibian declines, puta- tively caused widespread amphibian losses in genus Atelopus via increased regional temperature variability, which can

Rohr, Jason

90

Temperature variability and childhood pneumonia: an ecological study  

PubMed Central

Background Few data on the relationship between temperature variability and childhood pneumonia are available. This study attempted to fill this knowledge gap. Methods A quasi-Poisson generalized linear regression model combined with a distributed lag non-linear model was used to quantify the impacts of diurnal temperature range (DTR) and temperature change between two neighbouring days (TCN) on emergency department visits (EDVs) for childhood pneumonia in Brisbane, from 2001 to 2010, after controlling for possible confounders. Results An adverse impact of TCN on EDVs for childhood pneumonia was observed, and the magnitude of this impact increased from the first five years (2001–2005) to the second five years (2006–2010). Children aged 5–14 years, female children and Indigenous children were particularly vulnerable to TCN impact. However, there was no significant association between DTR and EDVs for childhood pneumonia. Conclusions As climate change progresses, the days with unstable weather pattern are likely to increase. Parents and caregivers of children should be aware of the high risk of pneumonia posed by big TCN and take precautionary measures to protect children, especially those with a history of respiratory diseases, from climate impacts. PMID:24916742

2014-01-01

91

High Temperature Variable Conductance Heat Pipes for Radioisotope Stirling Systems  

NASA Technical Reports Server (NTRS)

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.

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

2009-01-01

92

Variability in daily, zonal mean lower-stratospheric temperatures  

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

93

High Temperature Variable Conductance Heat Pipes for Radioisotope Stirling Systems  

NASA Astrophysics Data System (ADS)

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.

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

2009-03-01

94

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

Microsoft Academic Search

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

Guillermo P. Podestfi; Peter W. Glynn

1997-01-01

95

Equilibrating temperature-like variables in jammed granular subsystems  

E-print Network

Although jammed granular systems are athermal, several thermodynamic-like descriptions have been proposed which make quantitative predictions about the distribution of volume and stress within a system and provide a corresponding temperature-like variable. We perform experiments with an apparatus designed to generate a large number of independent, jammed, two-dimensional configurations. Each configuration consists of a single layer of photoelastic disks supported by a gentle layer of air. New configurations are generated by alternately dilating and re-compacting the system through a series of boundary displacements. Within each configuration, a bath of particles surrounds a smaller subsystem of particles with a different inter-particle friction coefficient than the bath. The use of photoelastic particles permits us to find all particle positions as well as the vector forces at each inter-particle contact. By comparing the temperature-like quantities in both systems, we find compactivity (conjugate to the volume) does not equilibrate between the systems, while the angoricity (conjugate to the stress) does. Both independent components of the angoricity are linearly dependent on the hydrostatic pressure, in agreement with predictions of the stress ensemble.

James G. Puckett; Karen E. Daniels

2012-07-31

96

High Temperature Variable Conductance Heat Pipes for Radioisotope Stirling Systems  

SciTech Connect

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.

Tarau, Calin; Walker, Kara L.; Anderson, William G. [Advanced Cooling Technologies, Inc. 1046 New Holland Ave. Lancaster, PA 17601 (United States)

2009-03-16

97

A High Temperature Hermetic Primer and a Variable Spring Tester  

SciTech Connect

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.

Begeal, D.R.

1994-05-01

98

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

PubMed

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

Martin, Rachel W; Zilm, Kurt W

2004-06-01

99

Temperature variable optimization for precision machine tool thermal error compensation on optimal threshold  

NASA Astrophysics Data System (ADS)

Machine tool thermal error is an important reason for poor machining accuracy. Thermal error compensation is a primary technology in accuracy control. To build thermal error model, temperature variables are needed to be divided into several groups on an appropriate threshold. Currently, group threshold value is mainly determined by researchers experience. Few studies focus on group threshold in temperature variable grouping. Since the threshold is important in error compensation, this paper arms to find out an optimal threshold to realize temperature variable optimization in thermal error modeling. Firstly, correlation coefficient is used to express membership grade of temperature variables, and the theory of fuzzy transitive closure is applied to obtain relational matrix of temperature variables. Concepts as compact degree and separable degree are introduced. Then evaluation model of temperature variable clustering is built. The optimal threshold and the best temperature variable clustering can be obtained by setting the maximum value of evaluation model as the objective. Finally, correlation coefficients between temperature variables and thermal error are calculated in order to find out optimum temperature variables for thermal error modeling. An experiment is conducted on a precise horizontal machining center. In experiment, three displacement sensors are used to measure spindle thermal error and twenty-nine temperature sensors are utilized to detect the machining center temperature. Experimental result shows that the new method of temperature variable optimization on optimal threshold successfully worked out a best threshold value interval and chose seven temperature variables from twenty-nine temperature measuring points. The model residual of z direction is within 3 ?m. Obviously, the proposed new variable optimization method has simple computing process and good modeling accuracy, which is quite fit for thermal error compensation.

Zhang, Ting; Ye, Wenhua; Liang, Ruijun; Lou, Peihuang; Yang, Xiaolan

2013-01-01

100

New variable low-temperature scanning tunneling microscope for use in ultrahigh vacuum  

E-print Network

; accepted for publication 15 November 1994) We describe the design and characterization of a new variable ei- ther exist only at low temperature or are best seen at low temperature. An example of phase

101

Predicting germination response of four cool-season range grasses to field-variable temperature regimes  

Microsoft Academic Search

Germination of non-dormant seeds under variable-temperature conditions can be predicted from constant-temperature germination data if it is assumed that instantaneous germination rate is independent of thermal history. Thermal-response models of this type have not been validated under simulated field-variable temperature conditions that vary in diurnal pattern, diurnal range and longer-term trends in mean–daily temperature. The purpose of this experiment was

S. P Hardegree; S. S Van Vactor

1999-01-01

102

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...

103

An ignored variable: solution preparation temperature in protein crystallization  

PubMed Central

Protein crystallization is affected by many parameters, among which certain parameters have not been well controlled. The temperature at which the protein and precipitant solutions are mixed (i.e., the ambient temperature during mixing) is such a parameter that is typically not well controlled and is often ignored. In this paper, we show that this temperature can influence protein crystallization. The experimental results showed that both higher and lower mixing temperatures can enhance the success of crystallization, which follows a parabolic curve with an increasing ambient temperature. This work illustrates that the crystallization solution preparation temperature is also an important parameter for protein crystallization. Uncontrolled or poorly controlled room temperature may yield poor reproducibility in protein crystallization. PMID:25597864

Chen, Rui-Qing; Lu, Qin-Qin; Cheng, Qing-Di; Ao, Liang-Bo; Zhang, Chen-Yan; Hou, Hai; Liu, Yong-Ming; Li, Da-Wei; Yin, Da-Chuan

2015-01-01

104

Western Arctic Ocean temperature variability during the last Jesse R. Farmer,1,2  

E-print Network

Western Arctic Ocean temperature variability during the last 8000 years Jesse R. Farmer,1,2 Thomas in the eastern Arctic Ocean. By comparison, the 0.5 to 0.7°C warm tem- perature anomaly identified. Dwyer, L. D. Keigwin, and R. C. Thunell (2011), Western Arctic Ocean temperature variability during

Long, Bernard

105

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

Microsoft Academic Search

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

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

2003-01-01

106

Mean seasonal and spatial variability in global surface air temperature  

Microsoft Academic Search

Using terrestrial observations of shelter-height air temperature and shipboard measurements, a global climatology of mean monthly surface air temperature has been compiled. Data were obtained from ten sources, screened for coding errors, and redundant station records were removed. The combined data base consists of 17 986 independent terrestrial station records and 6 955 oceanic grid-point records. These data were then

D. R. Legates; C. J. Willmott

1990-01-01

107

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...

108

The role of increasing temperature variability in European summer heatwaves  

Microsoft Academic Search

Instrumental observations and reconstructions of global and hemispheric temperature evolution reveal a pronounced warming during the past ~150 years. One expression of this warming is the observed increase in the occurrence of heatwaves. Conceptually this increase is understood as a shift of the statistical distribution towards warmer temperatures, while changes in the width of the distribution are often considered small.

Christoph Schär; Pier Luigi Vidale; Daniel Lüthi; Christoph Frei; Christian Häberli; Mark A. Liniger; Christof Appenzeller

2004-01-01

109

Seasonal variability in Arctic temperatures during the early Eocene  

NASA Astrophysics Data System (ADS)

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.

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

2009-12-01

110

Seasonal variability in Arctic temperatures during early Eocene time  

NASA Astrophysics Data System (ADS)

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.

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

2010-08-01

111

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

NASA Astrophysics Data System (ADS)

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.

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

2014-12-01

112

Temperature and salinity variability in thermohaline staircase layers  

E-print Network

A moored profiler record from the western tropical North Atlantic provides the first continuous time series of temperature, salinity and velocity profiles in a thermohaline staircase. Variations in the intensity of layering ...

Stuebe, David Allen

2005-01-01

113

Variable Temperature Performance of a Si(Li) Detector Stack  

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

114

Western Arctic Ocean temperature variability during the last 8000 years  

USGS Publications Warehouse

We reconstructed subsurface (?200–400 m) ocean temperature and sea-ice cover in the Canada Basin, western Arctic Ocean from foraminiferal ?18O, ostracode Mg/Ca ratios, and dinocyst assemblages from two sediment core records covering the last 8000 years. Results show mean temperature varied from ?1 to 0.5°C and ?0.5 to 1.5°C at 203 and 369 m water depths, respectively. Centennial-scale warm periods in subsurface temperature records correspond to reductions in summer sea-ice cover inferred from dinocyst assemblages around 6.5 ka, 3.5 ka, 1.8 ka and during the 15th century Common Era. These changes may reflect centennial changes in the temperature and/or strength of inflowing Atlantic Layer water originating in the eastern Arctic Ocean. By comparison, the 0.5 to 0.7°C warm temperature anomaly identified in oceanographic records from the Atlantic Layer of the Canada Basin exceeded reconstructed Atlantic Layer temperatures for the last 1200 years by about 0.5°C.

Farmer, Jesse R.; Cronin, Thomas M.; De Vernal, Anne; Dwyer, Gary S.; Keigwin, Loyd D.; Thunell, Robert C.

2011-01-01

115

The temperature variability and heat waves in Serbia  

NASA Astrophysics Data System (ADS)

Temperature extremes are an important aspect of any climate change because ecosystems and societal responses are most sensitive to them. During July and August 2007 record values of temperatures were observed in south-eastern Europe. Serbia, Bulgaria and Greece were the European countries most affected by the heat wave. Record values of the maximum temperatures were observed over almost the whole territory of Serbia and in Smederevska Palanka, a temperature of 44.9 °C in July was registered, which was the absolute maximum value ever recorded. The highest increase over the previous absolute maximum temperature, dating back to 1888, of 3.1 °C was registered in Belgrade. In Serbia, the mean summer temperature of 2007 exceeded the 1961 - 1990 mean by 3 °C, corresponding to an excess of up to 4 standard deviations. Also, the mean July temperature in 2007 exceeded the 1961 - 1990 mean by 3.3 °C, corresponding to an excess of up to 3 standard deviations. The Warm Spell Duration Indicator (WSDI), from which the duration and severity of the heat waves are estimated, was applied to the series of the daily maximum temperatures in Smederevska Palanka (SP). An extraordinary heat wave occurred in Serbia from July 14 to July 24 in 2007. An analysis of the daily maximum temperatures and heat waves during the summer of 2007 revealed significant changes in the trends of anomalies and extreme (90 %) quantiles. 1987, 2007 and 1998 were the three years with the longest heat waves from the beginning of measurements, having a duration of 13, 11 and 10 days, respectively. The longest heat wave observed in 1987 did not reach the severity of the heat wave in July 2007. The atmospheric circulation at 500-hPa resulted in the horizontal advection of warm air masses from northern Africa across central and eastern Mediterranean towards the Balkans. The 500-hPa geopotential anomalies (according to the reference period 1961 - 1990) of the summer and July 2007 exceeded 35 and 40 gpm over Serbia, respectively. The warm advection was manifested in temperature anomalies over Serbia, reaching up to 3.5 and 4.0 °C for the summer and July 2007, respectively.

Unkasevic, M.; Tosic, I.

2010-09-01

116

Diurnal variability of upper ocean temperatures from microwave satellite measurements and Argo profiles  

E-print Network

Diurnal variability of upper ocean temperatures from microwave satellite measurements and Argo by pairing Argo temperature profiles with geographically colocated Advanced Microwave Scanning Radiometer the two data sets. Daytime SSTs are warmer than Argo 5 m temperatures in low-wind conditions, as expected

Gille, Sarah T.

117

Comparing variability and trends in observed and modelled globalmean surface temperature  

E-print Network

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

118

A thermo-mechanical fatigue damage model for variable temperature and loading amplitude conditions  

Microsoft Academic Search

A fatigue life prediction method for thermo-mechanical fatigue damage under variable temperature and loading amplitudes was proposed. In this approach, a rainflow cycle counting technique was used to extract cycle counts from the mechanical loading history. For each loading cycle, an equivalent damage temperature was determined. Once the equivalent temperature was used, the loop would be guaranteed closed. This approach

Hong Tae Kang; Yung-Li Lee; Jim Chen; David Fan

2007-01-01

119

Surface air temperature variability in global climate models  

E-print Network

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

Davy, Richard

2012-01-01

120

High temperature VSCF (Variable Speed Constant Frequency) generator system  

NASA Astrophysics Data System (ADS)

The high temperature VSCF generator program was designed to develop a generating system capable of withstanding constantly high oil-in temperatures of 200 C in an ambient environment of 200 C. This is a requirement due to anticipated new fighter aircraft designs that will not be capable of cooling the oil to 100 C as in today's designs due to size restrictions of the heat exchanger and/or extended operation of the aircraft at supersonic speeds. The generator uses composite material to withstand the constant use of 200 C inlet oil.

Maphet, Thomas Allen; McCabria, Jack Lee; Kouba, Carroll Charles; Mitchell, James Thomas; Kwiecinski, James Robert

1989-04-01

121

Amplification and dampening of soil respiration by changes in temperature variability  

USGS Publications Warehouse

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.

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

2011-01-01

122

Temporal changes and variability in temperature series over Peninsular Malaysia  

NASA Astrophysics Data System (ADS)

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.

Suhaila, Jamaludin

2015-02-01

123

Natural convection along slender vertical cylinders with variable surface temperature  

Microsoft Academic Search

Natural convection in laminar boundary layers along slender vertical cylinders is analyzed for the situation in which the wall temperature T{sub w}(x) varies arbitrarily with the axial coordinate x. The governing boundary layer equations along with the boundary conditions are first cast into a dimensionless form by a nonsimilar transformation and the resulting system of equations is then solved by

H. R. Lee; T. S. Chen; B. F. Armaly

1988-01-01

124

Tropical sea surface temperature variability near the Oligocene - Miocene boundary  

NASA Astrophysics Data System (ADS)

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

Zhang, Y.; Pagani, M.

2010-12-01

125

Variable temperature large scan range hall probe microscope  

NASA Astrophysics Data System (ADS)

To understand the factors limiting the critical currents of superconducting films, we have built a scanning probe microscope to image flux penetration and current flow. A room temperature stepper-motor based 3-axis stage allows a 1×1cm scan range and submicron resolution. The stage feeds through to a flow cryostat that controls the sample temperature from 4K to 300K. The microscope can accomodate various sensors; it has been tested with a hall probe, microfabricated from a high-mobility 2-DEG, which was designed to measure the component of magnetic field perpendicular to the sample plane, but which can also be reoriented to measure in-plane components. Combining these components allows reconstruction of local sheet current density without the instability introduced by inverting an integral equation.

Dinner, Rafael; Moler, K. A.; Beasley, M. R.

2004-03-01

126

Variable-Temperature-Gradient Device for Solidification Research  

NASA Technical Reports Server (NTRS)

Device for research in solidification and crystal growth allows crystallization of melt observed as occurs. Temperature gradient across melt specimen increased or decreased rapidly while solidification front proceeds at constant speed across sample. Device moves sample at same speed, thereby holding position of liquid/solid interface stationary within field of optical microscope. Device, variabletemperature-gradient microscope stage, used to study crystal growth at constant rate while thermal driving force is varied.

Kaukler, W. F.

1985-01-01

127

Pacific interdecadal variability in this century's sea surface temperatures  

Microsoft Academic Search

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

Yi Chao; Michael Ghil; James C. McWilliams

2000-01-01

128

Temperature and precipitation variability in the European Alps since 1500  

Microsoft Academic Search

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

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

2005-01-01

129

Long-Term Variability of Stratospheric Temperature Above Central Antarctica  

NASA Astrophysics Data System (ADS)

Long-term variations of atmospheric temperature at different isobaric surfaces above central Antarctica and their possible coupling with correspondent changes in the near-Earth space were studied. Data of atmospheric balloon sounding at two Antarctic intercontinental stations Vostok and Amundsen-Scott (South Pole) taken for the last 40 years were used in this study. A central part of the Antarctica continent with its minimum of man-made pollution, uniformity of severe thermal and circulation regimes is an ideal place for study of the real climatic changes. It was found that stratospheric temperature at both stations averaged seasonally or annually does not demonstrate any meaningful correlation with correspondent sunspot number variations. On the other hand there is a notable correlation (r > 0,6) between stratospheric temperature at both stations and annually averaged values of the solar wind dynamic pressure. The latter parameter whose long-term time series were originally calculated by the authors is proportional to energy transferred to the Earth system " ma g n e t o s p here -ionosphere -atmosphere " from the outer space. A concept of the global electric circuit with a Electro-Motive Force generator located at the dayside magnetopause and driven by the solar wind energy is one of the possible realistic physical mechanisms capable to explain interaction between solar wind and middle atmosphere. Electrically conducting layers of ionosphere, ionic region in stratosphere and the Earth surface are the passive elements of this scheme. Mutual coupling between stratosphere thermal regimes at two stations (Vostok and South Pole) demonstrates obvious seasonal dependence: there is a good correlation between them in summer while it disappears in winter and equinoxes. It was found also that stratospheric temperature above South Pole Station varies in the same manner as correspondent parameter above North Pole as reported previously by Labitzke and Naujokat (2000). At both geographic poles stratospheric temperature had obvious tendency to warming in 1972-1995. On the other hand , the correspondent Vostok data demonstrate clear tendency to cooling in this period. Possible explanations of these results are given.

Shirochkov, A.; Makarova, L.

130

[Effects of variable temperature on organic carbon mineralization in typical limestone soils].  

PubMed

Soil sampling in the field and incubation experiment in the laboratory were conducted to investigate the responses of soil organic carbon (SOC) mineralization to variable temperature regimes in the topsoil of limestone soils from forest land and dry land. Two incubated limestone soils were sampled from the 0-10 cm layers of typical forest land and dry land respectively, which were distributed in Tianlong Mountain area of Puding county, Guizhou province. The soils were incubated for 56 d under two different temperature regimes including variable temperature (range: 15-25 degrees C, interval: 12 h) and constant temperature (20 degrees C), and the cumulative temperature was the same in the two temperature treatments. In the entire incubation period (56 d), the SOC cumulative mineralization (63.32 mg x kg(-1)) in the limestone soil from dry land (SH) under the variable temperature was lower than that (63.96 mg x kg(-1)) at constant 20 degrees C, and there was no significant difference in the SOC cumulative mineralization between the variable and constant temperature treatments (P < 0.05). While the cumulative mineralization (169.46 mg x kg(-1)) of organic carbon in the limestone soil from forest land (SL) under the variable temperature was significantly lower than that (209.52 mg x kg(-1)) at constant 20 degrees C. The results indicated that the responses of SOC mineralization to the variable temperature were obviously different between SL and SH soils. The SOC content and composition were significantly different between SL and SH soils affected by vegetation and land use type, which suggested that SOC content and composition were important factors causing the different responses of SOC mineralization to variable temperature between SL and SH soils. In addition, the dissolved organic carbon (DOC) content of two limestone soils were highly (P < 0.01) positively correlated with daily mineralization of soil organic carbon in both temperature treatments, which implied that controlling DOC production was an important way for the temperature influence of SOC mineralization. During the incubation period, SOC mineralization was independent of microbial biomass carbon (MBC) content in both temperature treatments. Combined with mineralization kinetic data, the results showed that, compared to constant temperature 20 degrees C, variable temperature mainly influenced SOC mineralization by changing microbial community activity rather than by changing microbial quantity. PMID:25639108

Wang, Lian-Ge; Gao, Yan-Hong; Ding, Chang-Huan; Ci, En; Xie, De-Ti

2014-11-01

131

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

E-print Network

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

Huang, Y.; Sun, D.

2006-01-01

132

Atmospheric influence on the interannual variability of the seasonal Diurnal Temperature Range over Europe  

Microsoft Academic Search

In this paper the relationship between the variability of the seasonal Diurnal Temperature Range (DTR) over Europe and the atmospheric circulation has been investigated. The spatiotemporal variability of the seasonal DTR over Europe and the influence of largescale atmospheric circulation on DTR have been examined by means of Empirical Orthogonal Function (EOF) analysis and composite map analysis. Based on the

M. Ionita; G. Lohmann; N. Rimbu

2011-01-01

133

Linking global climate and temperature variability to widespread amphibian declines putatively caused by disease  

PubMed Central

The role of global climate change in the decline of biodiversity and the emergence of infectious diseases remains controversial, and the effect of climatic variability, in particular, has largely been ignored. For instance, it was recently revealed that the proposed link between climate change and widespread amphibian declines, putatively caused by the chytrid fungus Batrachochytrium dendrobatidis (Bd), was tenuous because it was based on a temporally confounded correlation. Here we provide temporally unconfounded evidence that global El Niño climatic events drive widespread amphibian losses in genus Atelopus via increased regional temperature variability, which can reduce amphibian defenses against pathogens. Of 26 climate variables tested, only factors associated with temperature variability could account for the spatiotemporal patterns of declines thought to be associated with Bd. Climatic predictors of declines became significant only after controlling for a pattern consistent with epidemic spread (by temporally detrending the data). This presumed spread accounted for 59% of the temporal variation in amphibian losses, whereas El Niño accounted for 59% of the remaining variation. Hence, we could account for 83% of the variation in declines with these two variables alone. Given that global climate change seems to increase temperature variability, extreme climatic events, and the strength of Central Pacific El Niño episodes, climate change might exacerbate worldwide enigmatic declines of amphibians, presumably by increasing susceptibility to disease. These results suggest that changes to temperature variability associated with climate change might be as significant to biodiversity losses and disease emergence as changes to mean temperature. PMID:20404180

Rohr, Jason R.; Raffel, Thomas R.

2010-01-01

134

Temporal and spatial variability of surface temperature over Texas  

E-print Network

workstation crises and related dilly innias. Finally, I would like to extend thanks to Professor John F. Griffiths and Dr. . James P. McGuirk. both of the Meteorology Department. for their fruitful discussions with me about the finer points of EOF analysis... with water is considered to be the main factor in producing this contrast, known as the continentality effect. Prescott and Collins (1951) calculated the lag of suri'ace temperature behind solar radiation on a global basis and for thc United States using...

Moninski, Anthony David

1995-01-01

135

Long-term variability in Arctic sea surface temperatures  

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

136

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

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

137

Influence of Climate on Emergency Department Visits for Syncope: Role of Air Temperature Variability  

PubMed Central

Background Syncope is a clinical event characterized by a transient loss of consciousness, estimated to affect 6.2/1000 person-years, resulting in remarkable health care and social costs. Human pathophysiology suggests that heat may promote syncope during standing. We tested the hypothesis that the increase of air temperatures from January to July would be accompanied by an increased rate of syncope resulting in a higher frequency of Emergency Department (ED) visits. We also evaluated the role of maximal temperature variability in affecting ED visits for syncope. Methodology/Principal Findings We included 770 of 2775 consecutive subjects who were seen for syncope at four EDs between January and July 2004. This period was subdivided into three epochs of similar length: 23 January–31 March, 1 April–31 May and 1 June–31 July. Spectral techniques were used to analyze oscillatory components of day by day maximal temperature and syncope variability and assess their linear relationship. There was no correlation between daily maximum temperatures and number of syncope. ED visits for syncope were lower in June and July when maximal temperature variability declined although the maximal temperatures themselves were higher. Frequency analysis of day by day maximal temperature variability showed a major non-random fluctuation characterized by a ?23-day period and two minor oscillations with ?3- and ?7-day periods. This latter oscillation was correlated with a similar ?7-day fluctuation in ED visits for syncope. Conclusions/Significance We conclude that ED visits for syncope were not predicted by daily maximal temperature but were associated with increased temperature variability. A ?7-day rhythm characterized both maximal temperatures and ED visits for syncope variability suggesting that climate changes may have a significant effect on the mode of syncope occurrence. PMID:21818372

Galli, Andrea; Barbic, Franca; Borella, Marta; Costantino, Giorgio; Perego, Francesca; Dipaola, Franca; Casella, Francesco; Duca, Pier Giorgio; Diedrich, Andrè; Raj, Satish; Robertson, David; Porta, Alberto; Furlan, Raffaello

2011-01-01

138

Note: A variable temperature cell for spectroscopy of thin films  

NASA Astrophysics Data System (ADS)

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.

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

2013-04-01

139

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

PubMed

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

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

2013-04-01

140

Phosphonium chloromercurate room temperature ionic liquids of variable composition.  

PubMed

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

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

2013-12-16

141

Variable Temperature (1.6–300 K) X-Band EPR System with a Variable Cavity Coupler  

Microsoft Academic Search

A variable temperature (1.6–300 K) electron paramagnetic resonance (EPR) X-band spectrometer is described. The spectrometer is a Varian V-4502 EPR spectrometer using a V-4500–42 X-band microwave bridge and a V-K3525 superheterodyne accessory. The Dewar system is an Andonian Associates Cryostat with a 4.43 cm i.d. sample area. The sample cavity resonates in the TE102 rectangular mode. The coupling of the

J. A. MacKinnon

1972-01-01

142

Regional temperature variability in the European Alps: 1760-1998 from homogenized instrumental time series  

Microsoft Academic Search

This paper investigates temperature variability in the Alps and their surroundings based on 97 instrumental series of monthly mean temperatures. A discussion of the initial homogenizing procedure illustrates its advantages and risks. A comparison of the homogenized series with the original series clearly shows the necessity to homogenize. Each of the original series had breaks (an average of five per

Reinhard Böhm; Ingeborg Auer; Michele Brunetti; Maurizio Maugeri; Teresa Nanni; Wolfgang Schöner

2001-01-01

143

Late Holocene variability of upper North Atlantic Deep Water temperature and salinity  

E-print Network

Late Holocene variability of upper North Atlantic Deep Water temperature and salinity Thomas M equation. Results suggest that the temperature of upper North Atlantic Deep Water (dominated by Labrador waters to intermediate depths. Our reconstructed late Holocene ranges in upper North Atlantic Deep Water

Born, Andreas

144

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

Microsoft Academic Search

Using 100 years of global temperature anomaly data, we have performed a singular 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

Michael E. Mann; Jeffrey Park

1994-01-01

145

Sahel Precipitation Variability and Global Sea Surface Temperature Forcing  

NASA Astrophysics Data System (ADS)

In the last 50 years or so, the Sahel region in sub-Saharan Africa has experienced two multi-decadal wet and dry periods separated by a relatively sharp transition. The onset of the dry episode in the Sahel is associated with the start of a significant warming trend in Southern Hemisphere sea surface temperatures (SST) that persisted well into the late 1990's. It has been stipulated, based on general circulation model (GCM) experiments, that the SST rise in the southern ocean basins is the predominant driver of rainfall patterns over the Sahel. Here we support this notion by comparing the observed rate of change in Southern Hemisphere SST with that of Sahel summertime rainfall. We examine the variations in each ocean basin separately and find that the drought pattern is most prominently associated with SST changes in the Indian Ocean, which display maximum warming rates simultaneously with the wet to dry shift in the Sahel. We provide further support to the role of the Indian Ocean using results from GCM integrations forced with observed Indian Ocean SST values and climatological values elsewhere, which effectively recreate the dry Sahel rainfall pattern. While the variations in equatorial Pacific SST associated with El Ni¤o have been found to have an effect on Sahel rainfall during the summer months, their influence does not appear to be significantly connected with the prolonged drought episode. The dry period was accentuated by two severe droughts in the early 1970's and 1980s, which generated very different repercussions for the Sahelian people. The first drought resulted in widespread famine and death while the second more severe drought in 1983-84 generated very few casualties. The political and socioeconomic assessment of these episodes suggests that the extensive loss of life was due to inefficient transportation of supplies to the starving populations. International aid organizations initiated famine protection programs following the 1970's drought that helped to effectively counteract devastating famine in the 1980's.

Bach, D. E.; Kushnir, Y.; Seager, R.; Goddard, L.; Giannini, A.

2003-12-01

146

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

NASA Astrophysics Data System (ADS)

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.

Sourkova, G.; Pona, C.

147

Complexation of lanthanides with nitrate at variable temperatures: thermodynamics and coordination modes.  

PubMed

Complexation of neodymium(III) with nitrate was studied at variable temperatures (25, 40, 55, and 70 degrees C) by spectrophotometry and microcalorimetry. The NdNO(3)(2+) complex is weak and becomes slightly stronger as the temperature is increased. The enthalpy of complexation at 25 degrees C was determined by microcalorimetry to be small and positive, 1.5 +/- 0.2 kJ x mol(-1), in good agreement with the trend of the stability constant at variable temperatures. Luminescence emission spectra and the lifetime of Eu(III) in nitrate solutions suggest that inner-sphere and bidentate complexes form between trivalent lanthanides (Nd(3+) and Eu(3+)) and nitrate in aqueous solutions. A specific ion interaction approach was used to obtain the stability constants of NdNO(3)(2+) at infinite dilution and variable temperatures. PMID:19115981

Rao, Linfeng; Tian, Guoxin

2009-02-01

148

Controls of subsurface temperature variability in a western boundary upwelling system  

NASA Astrophysics Data System (ADS)

The mechanisms controlling subsurface temperature variability on the outer shelf in a western boundary upwelling system are quantified using observations from a mooring deployed off Cabo Frio, Brazil. Results from a multiple linear regression analysis reveal that, in addition to low-frequency variations associated with the seasonal evolution of temperature, the dominant mechanisms controlling temperature variability are wind stress curl-driven upwelling, cross-isobath transport, the proximity of the Brazil Current to the shelf break, and perhaps changes in the strength of tidal mixing associated with the spring-neap cycle. The influence of the proximity of the Brazil Current decreases strongly with depth, being restricted to the top 80 m. Regression coefficients indicate that the relative contributions from the different forcings are roughly similar and that no single process has a dominant role explaining temperature variability near the shelf break. These suggest that successful modeling efforts in the region must adequately represent each of those processes.

Belem, Andre L.; Castelao, Renato M.; Albuquerque, Ana Luiza

2013-04-01

149

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

PubMed

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

Laepple, Thomas; Huybers, Peter

2014-11-25

150

Recent Climate Variability in Antarctica from Satellite-derived Temperature Data  

NASA Technical Reports Server (NTRS)

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.

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

2004-01-01

151

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

NASA Astrophysics Data System (ADS)

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.

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

2015-01-01

152

Modes of variability of global sea surface temperature, free atmosphere temperature and oceanic surface energy flux  

Microsoft Academic Search

Monthly mean sea surface temperature (SST), free air temperature from satellite microwave sounding units (MSU) and oceanic surface energy fluxes are subjected to empirical orthogonal function (EOF) analysis for a common decade to investigate the physical relationships involved. The first seasonal modes of surface solar energy flux and SST show similar inter-hemispheric patterns with an annual cycle. Solar flux appears

Wenjie Hu; Reginald E. Newell; Zhong-Xiang Wu

1994-01-01

153

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

NASA Technical Reports Server (NTRS)

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.

Choudhury, B. J.

1982-01-01

154

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

NASA Astrophysics Data System (ADS)

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

Okada, Masahiro; Kakehashi, Masayuki

2014-03-01

155

Patterns of northern emisphere mid-latitude temperature variability in a 500-year climate simulation with variable radiative forcing  

NASA Astrophysics Data System (ADS)

This study is based on a 500-year long simulation carried out with an AOGCM which computes the climate evolution from the 15th to the end of the 20th century. The simulation includes a VRF (Variable Radiative Forcing) which accounts for variations of the solar activity, volcanic eruptions and recent increase of GHG (Green House Gases) concentration. The results are compared with a 1000-year long CTR (ConTRol) simulation which is based on a constant radiative forcing, corresponding to the 1990 level. The model, called ECHO-G model, consists of the global atmospheric model ECHAM4, at T30 resolution, and of the ocean circulation model HOPE-G, at 2.8 degs resolution. A clear (seasonal) signature of the radiative forcing variability on the temperature distribution is identified from the analysis of the fields associated with extreme radiative forcing values. The effect is present, though smaller, also on the sea level pressure fields. The dynamics behind these temperature and sea level pressure patterns are described and their importance for the temperature of the mid-latitudes in the Northern emisphere is shown.

Lionello, P.; de Zolt, S.; Zorita, E.

2003-04-01

156

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

NASA Technical Reports Server (NTRS)

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.

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

1999-01-01

157

Constraints on the temperature inhomogeneity in quasar accretion discs from the ultraviolet-optical spectral variability  

NASA Astrophysics Data System (ADS)

The physical mechanisms of the quasar ultraviolet (UV)-optical variability are not well understood despite the long history of observations. Recently, Dexter & Agol presented a model of quasar UV-optical variability, which assumes large local temperature fluctuations in the quasar accretion discs. This inhomogeneous accretion disc model is claimed to describe not only the single-band variability amplitude, but also microlensing size constraints and the quasar composite spectral shape. In this work, we examine the validity of the inhomogeneous accretion disc model in the light of quasar UV-optical spectral variability by using five-band multi-epoch light curves for nearly 9 000 quasars in the Sloan Digital Sky Survey (SDSS) Stripe 82 region. By comparing the values of the intrinsic scatter ?int of the two-band magnitude-magnitude plots for the SDSS quasar light curves and for the simulated light curves, we show that Dexter & Agol's inhomogeneous accretion disc model cannot explain the tight inter-band correlation often observed in the SDSS quasar light curves. This result leads us to conclude that the local temperature fluctuations in the accretion discs are not the main driver of the several years' UV-optical variability of quasars, and consequently, that the assumption that the quasar accretion discs have large localized temperature fluctuations is not preferred from the viewpoint of the UV-optical spectral variability.

Kokubo, Mitsuru

2015-05-01

158

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

USGS Publications Warehouse

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

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

2007-01-01

159

Endotracheal temperature and humidity measurements in laryngectomized patients: intra- and inter-patient variability  

Microsoft Academic Search

This study assesses intra- and inter-patient variability in endotracheal climate (temperature and humidity) and effects of\\u000a heat and moister exchangers (HME) in 16 laryngectomized individuals, measured repeatedly (N = 47). Inhalation Breath Length (IBL) was 1.35 s without HME and 1.05 s with HME (P 2O\\/L (P P < 0.0001). For the temperature and humidity minimums, the inter-patient variability was much smaller than the short- and\\u000a long-term intra-patient

R. J. Scheenstra; S. H. Muller; A. Vincent; M. Sinaasappel; J. K. Zuur; Frans J. M. Hilgers

2009-01-01

160

A statistical approach to represent small-scale variability of permafrost temperatures due to snow cover  

NASA Astrophysics Data System (ADS)

In permafrost environments exposed to strong winds, drifting snow can create a small-scale pattern of strongly variable snow heights, which has profound implications for the thermal regime of the ground. Arrays of 26 to more than 100 temperature loggers were installed to record the distribution of ground surface temperatures within three study areas across a climatic gradient from continuous to sporadic permafrost in Norway. A variability of the mean annual ground surface temperature of up to 6°C was documented within areas of 0.5 km2. The observed variation can, to a large degree, be explained by variation in snow height. Permafrost models, employing averages of snow height for grid cells of, e.g., 1 km2, are not capable of representing such sub-grid variability. We propose a statistical representation of the sub-grid variability of ground surface temperatures and demonstrate that a simple equilibrium permafrost model can reproduce the temperature distribution within a grid cell based on the distribution of snow heights.

Gisnås, K.; Westermann, S.; Schuler, T. V.; Litherland, T.; Isaksen, K.; Boike, J.; Etzelmüller, B.

2014-11-01

161

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

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

162

Hybrid spin-crossover conductor exhibiting unusual variable-temperature electrical conductivity.  

PubMed

We describe the multistep synthesis of a new terthienyl-substituted QsalH ligand and an iron(3+) spin-crossover complex (1) containing this ligand, which electropolymerizes to produce a hybrid-conducting metallopolymer film (poly1). Variable-temperature magnetic susceptibility measurements demonstrate that spin-crossover is operative in the polymer film, and resistivity measurements on indium-tin oxide coated glass slides containing the polymer film exhibit intriguing temperature-dependent profiles. PMID:19831361

Djukic, Brandon; Lemaire, Martin T

2009-11-16

163

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

SciTech Connect

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.

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

2014-04-11

164

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

NASA Astrophysics Data System (ADS)

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

Connolly, Thomas P.; Lentz, Steven J.

2014-09-01

165

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

NASA Astrophysics Data System (ADS)

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.

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

2014-11-01

166

2T/5T Two-Axis Cryogen Free Superconducting Vector Magnet With Variable Temperature Space  

NASA Astrophysics Data System (ADS)

A conduction cooled 2T / 5T superconducting vector magnetic system with a variable temperature space was developed and tested. The system is based on a commercial two-stage 4 K Gifford-McMahon cryocooler with the cooling power of 1.5 W at 4.2 K. The cool down time of the magnet from room temperature to 3.2 K is 17 hours. The system provides sample temperature range of 6.0-300 K. The clear diameter of variable temperature space is 39 mm. A 5 T solenoid generates magnetic field in the vertical axis and a 2 T split coil generates field in the horizontal axis. The magnets are made of niobium-titanium wire wound on a copper former. A PC controlled rotary drive is applied to rotate a sample holder around the vertical axis. Thus the measured sample can be exposed to the magnetic field in any desired direction. A helium gas gap heat switch is used as a controllable thermal link between the variable temperature space and the 2nd stage to avoid overheating of the magnet at high temperatures of the sample. The system design, manufacturing and test results are presented.

Demikhov, E. I.; Demikhov, T. E.; Kostrov, E. A.; Lysenko, V. V.; Piskunov, N. A.

2014-05-01

167

Genetic variability and differentiation in the temperature niche component of the diatom Thalassiosira pseudonana  

Microsoft Academic Search

The acclimated reproduction rates of 14 clones of the diatom Thalassiosira pseudonana were measured at 12°, 16°, 20°, and 24°C. Reproduction rate increased monotonically with an increase in temperature in all 14 clones. Significant genetic variability in reproduction rates and electrophoretic mobility of isozymes were observed among clones within a population from a single water bottle collected in a warm

L. E. Brand; L. S. Murphy; R. R. L. Guillard; H.-t. Lee

1981-01-01

168

Comparison of the effects of selected variables on urban surface temperature  

Microsoft Academic Search

The intra-urban variation in surface temperature and its related natural and social variables region by region within a city was investigated in the study. The study area is Washington DC, USA. Data sources include one EOS Terra ASTER scene, census data and high spatial resolution (1m) color infrared DOQQ. The census tracts were used to partition the city into different

Weirong Chen; Guoqing Zhou

2004-01-01

169

Solar flux variability of Mars' exosphere densities and temperatures Jeffrey M. Forbes,1  

E-print Network

Solar flux variability of Mars' exosphere densities and temperatures Jeffrey M. Forbes,1 Frank G, the response of Mars' exosphere to long-term solar change is established and compared to that of Earth conditions) change only 36­50% as much as those at Earth as solar activity increases from solar minimum

Forbes, Jeffrey

170

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

Microsoft Academic Search

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

Peter C. Chu; Shihua Lu; Yuchun Chen

1997-01-01

171

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

NASA Technical Reports Server (NTRS)

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.

Floyd, Samuel R.; Puc, Bernard P.

1992-01-01

172

Effects of ambient temperature, humidity, and other meteorological variables on hospital admissions for angina pectoris  

Microsoft Academic Search

Background: Seasonal peaks in cardiovascular disease incidence have been widely reported, suggesting weather has a role.Design The aim of our study was to determine the influence of climatic variables on angina pectoris hospital admissions.Methods: We correlated the daily number of angina cases admitted to a western Sicilian hospital over a period of 12 years and local weather conditions (temperature, humidity,

Maurizio G Abrignani; Salvatore Corrao; Giovan B Biondo; Renzo M Lombardo; Paola Di Girolamo; Annabella Braschi; Alberto Di Girolamo; Salvatore Novo

2012-01-01

173

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

E-print Network

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

Poeppelmeier, Kenneth R.

174

Seasonal variability of salinity, temperature, turbidity and suspended chlorophyll in the Tweed Estuary  

Microsoft Academic Search

Results are presented from a campaign of measurements that were undertaken to examine seasonal variability in physical and chemical fluxes and processes within the Tweed Estuary during the period September 1996–August 1997. The study utilised monthly surveys, each of approximately 1 week duration. This article interprets a subset of the salinity, temperature, turbidity [suspended particulate matter (SPM) levels] and chlorophyll

R. J. Uncles; N. J. Bloomer; P. E. Frickers; M. L. Griffiths; C. Harris; R. J. M. Howland; A. W. Morris; D. H. Plummer; A. D. Tappin

2000-01-01

175

Concrete calcium leaching at variable temperature: experimental data and numerical model inverse  

E-print Network

Concrete calcium leaching at variable temperature: experimental data and numerical model inverse/DSU/SSIAD/BERIS, Fontenay-aux-Roses, France Abstract A simplified model for calcium leaching in concrete is presented found in the literature, for cement pastes and mortars as well as for concretes, with a satisfactory

Paris-Sud XI, Université de

176

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...

177

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

USGS Publications Warehouse

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.

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

2008-01-01

178

The role of temperature variability in stabilizing the mountain pine beetle-fungus mutualism.  

PubMed

As global climate patterns continue to change and extreme weather events become increasingly common, it is likely that many ecological interactions will be affected. One such interaction is the multipartite symbiosis that exists between the mountain pine beetle and two species of fungi, Grosmannia clavigera and Ophiostoma montium. In this mutualism, the fungi provide nutrition to the beetle, while the fungi benefit by being dispersed to new host trees. Multi-partite mutualisms are predicted to be unstable due to strong direct competition among symbionts or natural selection for superior over inferior mutualists. However, this mutualism has remained stable over long periods of evolutionary time. In this paper, we developed a temperature-based model for the spread of fungi within a tree and connected it to an existing model for mountain pine beetle development. Using this integrated model for fungal growth, we explored the possibility that temperature variability is a stabilizing mechanism for the mountain pine beetle-fungi mutualism. Of the three types of temperature variability we tested: intra-year, inter-year and variability due to transitioning between different thermal habitats (thermal migration), we found that thermal migration was the most robust stabilizing mechanism. Additionally, we found that the MPB attack density or spacing between fungal lesions also had a significant effect on the stability of the system. High attack densities or close lesion spacings also tended to stabilize the system, regardless of temperature. PMID:23791850

Addison, A L; Powell, J A; Six, D L; Moore, M; Bentz, B J

2013-10-21

179

HadISDH land surface multi-variable humidity and temperature record for climate monitoring  

NASA Astrophysics Data System (ADS)

HadISDH.2.0.0 is the first gridded, multi-variable humidity and temperature climate-data product that is homogenised and annually updated. It provides physically consistent estimates for specific humidity, vapour pressure, relative humidity, dew point temperature, wet bulb temperature, dew point depression and temperature. It is a monthly-mean gridded (5° by 5°) product with uncertainty estimates that account for spatio-temporal sampling, climatology calculation, homogenisation and irreducible random measurement effects. It provides a unique tool for the monitoring of a variety of humidity-related variables which have different impacts and implications for society. HadISDH.2.0.0 is shown to be in good agreement both with other estimates where they are available, and with theoretical understanding. The dataset is available from 1973 to the present. The theme common to all variables is of a warming world with more water vapour present in the atmosphere. The largest increases in water vapour are found over the tropics and Mediterranean. Over the tropics and high northern latitudes the surface air over land is becoming more saturated. However, despite increasing water vapour over the mid-latitudes and Mediterranean, the surface air over land is becoming less saturated. These observed features may be due to atmospheric circulation changes, land-sea warming disparities and reduced water availability or changed land surface properties.

Willett, K. M.; Dunn, R. J. H.; Thorne, P. W.; Bell, S.; de Podesta, M.; Parker, D. E.; Jones, P. D.; Williams, C. N., Jr.

2014-06-01

180

HadISDH land surface multi-variable humidity and temperature record for climate monitoring  

NASA Astrophysics Data System (ADS)

HadISDH.2.0.0 is the first gridded, multi-variable humidity and temperature in situ observations-only climate-data product that is homogenised and annually updated. It provides physically consistent estimates for specific humidity, vapour pressure, relative humidity, dew point temperature, wet bulb temperature, dew point depression and temperature. It is a monthly mean gridded (5° by 5°) product with uncertainty estimates that account for spatio-temporal sampling, climatology calculation, homogenisation and irreducible random measurement effects. It provides a tool for the long-term monitoring of a variety of humidity-related variables which have different impacts and implications for society. It is also useful for climate model evaluation and reanalyses validation. HadISDH.2.0.0 is shown to be in good agreement both with other estimates and with theoretical understanding. The data set is available from 1973 to the present. The theme common to all variables is of a warming world with more water vapour present in the atmosphere. The largest increases in water vapour are found over the tropics and the Mediterranean. Over the tropics and high northern latitudes the surface air over land is becoming more saturated. However, despite increasing water vapour over the mid-latitudes and Mediterranean, the surface air over land is becoming less saturated. These observed features may be due to atmospheric circulation changes, land-sea warming disparities and reduced water availability or changed land surface properties.

Willett, K. M.; Dunn, R. J. H.; Thorne, P. W.; Bell, S.; de Podesta, M.; Parker, D. E.; Jones, P. D.; Williams, C. N., Jr.

2014-11-01

181

Impact of variable [CO2] and temperature on water transport structure-function relationships in Eucalyptus.  

PubMed

Nearly 30 years ago, Whitehead and Jarvis and Whitehead et al. postulated an elegant mechanistic explanation for the observed relationship between tree hydraulic structure and function, hypothesizing that structural adjustments promote physiological homeostasis. To date, this framework has been nearly completely overlooked with regard to varying atmospheric carbon dioxide ([CO(2)]). Here, we evaluated Whitehead's hypothesis of leaf water potential (?(l)) homeostasis in faster-growing (Eucalyptus saligna) and slower-growing (Eucalyptus sideroxylon) tree saplings grown under three [CO(2)] (pre-industrial, current and future) and two temperature (ambient and ambient + 4°C) treatments. We tested for relationships between physiological (stomatal conductance and ?(l)) and structural (leaf and sapwood areas (A(l), A(s)), height (h), xylem conductivity (k(s))) plant variables as a function of the [CO(2)] and temperature treatments to assess whether structural variables adjusted to maintain physiological homeostasis. Structural components (A(l), A(s), h) generally increased with [CO(2)] or temperature, while g(s) was negatively correlated with [CO(2)]. Contrary to Whitehead's hypothesis, ?(l) did not exhibit homeostasis in either species; elevated temperatures were associated with more negative ?(l) in faster-growing E. saligna, and less negative ?(l) in slower-growing E. sideroxylon. Moreover, individual structural variables were generally uncorrelated with ?(l). However, across both species, the integrated hydraulic property of leaf specific hydraulic conductance (K(l)) was positively correlated with an independent calculation of K(l) determined exclusively from leaf physiological variables. These results suggest that physiological homeostasis may not apply to saplings exposed to global change drivers including [CO(2)] and temperature. Nevertheless, Whitehead et al.'s formulation identified K(l) as a sensitive measure of plant structural-physiological co-variation across species. PMID:21712237

Phillips, Nathan G; Attard, Renee D; Ghannoum, Oula; Lewis, James D; Logan, Barry A; Tissue, David T

2011-09-01

182

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

NASA Astrophysics Data System (ADS)

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.

Gritsch, Christine; Zechmeister-Boltenstern, Sophie

2014-05-01

183

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

NASA Technical Reports Server (NTRS)

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.

Lim, Young-Kwon; Kim, Hae-Dong

2013-01-01

184

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

NASA Astrophysics Data System (ADS)

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 ?m 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.

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

2010-04-01

185

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

NASA Technical Reports Server (NTRS)

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.

Lee, Robert B., III

1992-01-01

186

How does stratospheric variability affect surface weather and climate?  

NASA Astrophysics Data System (ADS)

Changes to the stratosphere, due to both natural variability and ozone depletion, have substantial effects on surface weather and climate, especially at middle to high latitudes. Despite clear evidence of these impacts, the primary dynamics of this phenomenon are not yet well understood. Here we show that the stratospheric meridional circulation forces the column of air above the Arctic downwards into the troposphere, acting like a mechanical plunger that controls the day-to-day thickness of the troposphere. This vertical motion directly affects temperatures and the strength of jets in the mid- to upper troposphere. Raising and lowering of the Arctic tropopause layer leads to stretching and compression of the tropospheric column and a north-south dipole in surface pressure similar to the Northern Annular Mode.

Baldwin, Mark; Birner, Thomas

2013-04-01

187

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

NASA Astrophysics Data System (ADS)

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.

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

2014-07-01

188

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

USGS Publications Warehouse

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.

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

1987-01-01

189

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

NASA Technical Reports Server (NTRS)

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.

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

190

Elucidating the impact of temperature variability and extremes on cereal croplands through remote sensing.  

PubMed

Remote sensing-derived wheat crop yield-climate models were developed to highlight the impact of temperature variation during thermo-sensitive periods (anthesis and grain-filling; TSP) of wheat crop development. Specific questions addressed are: can the impact of temperature variation occurring during the TSP on wheat crop yield be detected using remote sensing data and what is the impact? Do crop critical temperature thresholds during TSP exist in real world cropping landscapes? These questions are tested in one of the world's major wheat breadbaskets of Punjab and Haryana, north-west India. Warming average minimum temperatures during the TSP had a greater negative impact on wheat crop yield than warming maximum temperatures. Warming minimum and maximum temperatures during the TSP explain a greater amount of variation in wheat crop yield than average growing season temperature. In complex real world cereal croplands there was a variable yield response to critical temperature threshold exceedance, specifically a more pronounced negative impact on wheat yield with increased warming events above 35 °C. The negative impact of warming increases with a later start-of-season suggesting earlier sowing can reduce wheat crop exposure harmful temperatures. However, even earlier sown wheat experienced temperature-induced yield losses, which, when viewed in the context of projected warming up to 2100 indicates adaptive responses should focus on increasing wheat tolerance to heat. This study shows it is possible to capture the impacts of temperature variation during the TSP on wheat crop yield in real world cropping landscapes using remote sensing data; this has important implications for monitoring the impact of climate change, variation and heat extremes on wheat croplands. PMID:24930864

Duncan, John M A; Dash, Jadunandan; Atkinson, Peter M

2015-04-01

191

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

NASA Astrophysics Data System (ADS)

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.

Suteanu, Cristian

2014-07-01

192

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

Microsoft Academic Search

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

David B. Enfield; Dennis A. Mayer

1997-01-01

193

A vertical inertial coarse approach for variable temperature scanned probe microscopy  

NASA Astrophysics Data System (ADS)

We have developed a variable temperature inertial coarse approach mechanism for use in scanned probe microscopy. This reliable micropositioner has a coarse range of 2.5 mm and can take individual steps of less than 10 nm from 4 to 300 K. This simple, compact device is both nonmagnetic and glueless. It is operational in both horizontal and vertical geometries and is driven by a low voltage sawtooth waveform. We report on the design and performance of the device.

Silveira, William R.; Marohn, John A.

2003-01-01

194

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

PubMed

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

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

2011-02-10

195

[Circadian analysis of sleep, rectal temperature and immunological and endocrinological variables in sleeping sickness: preliminary study].  

PubMed

A multidisciplinary study was conducted in 8 patients with neurological Human African Trypanosomiasis. The sleep-wake cycle followed an ultradian pattern which was more pronounced in patients with more severe symptoms. The EEG trace was consistently interrupted by numerous cyclic activation patterns with K complexes, rapid low amplitude elements and slow high voltage elements. Circadian rhythmicity was also disturbed in other physiological (rectal temperature), immunological (interleukins) or hormonal (cortisol, prolactin) variables, the disturbance being greater in severely hit patients. PMID:2208457

Gati, R; Tabaraud, F; Buguet, A; Bert, J; Tapie, P; Bittel, J; Sparkes, B; Breton, J C; Doua, F; Bogui, P

1990-01-01

196

Variable Discourse of Universe Fuzzy-PID Temperature Control System for Vacuum Smelting Based on PLC  

Microsoft Academic Search

In view of the vacuum smelting process temperature control for existence of non-linear big lag and the poor accuracy and so on. a kind of variable discourse of universe fuzzy-PID (PID-proportional integral derivative) high precision controller is designed, realization of this way based on Matlab\\/Simulink simulation and PLC(PLC-Programmable logic Controller) is provided, the new fuzzy-PID controller has fast response and

Yan Chen; Jin-hui Lei; Xue-bing Yang

2009-01-01

197

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

NASA Astrophysics Data System (ADS)

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.

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

2014-08-01

198

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

NASA Astrophysics Data System (ADS)

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

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

2009-01-01

199

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

NASA Astrophysics Data System (ADS)

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 ±2? 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; ?regression = 0.70°C, 1?), 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, 1?; 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.

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

2012-12-01

200

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

PubMed

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

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

2014-11-15

201

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

SciTech Connect

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.

Hays, Lance G

2014-07-07

202

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

NASA Astrophysics Data System (ADS)

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

Badruddin; Aslam, O. P. M.

2015-01-01

203

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

NASA Astrophysics Data System (ADS)

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.

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

204

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

SciTech Connect

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.

Olaru, A.M., E-mail: aolaru@mc.rwth-aachen.de; Bluemich, B.; Adams, A., E-mail: aadams@mc.rwth-aachen.de

2013-02-15

205

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

NASA Technical Reports Server (NTRS)

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.

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

2000-01-01

206

Hydrologic and temperature variability at Lake Titicaca over the past 50,000 years  

NASA Astrophysics Data System (ADS)

The Bolivian Altiplano has been the focus of many paleoclimate studies due to the important role it plays in the South American climate system. Although the timing of climate shifts in this region is relatively well known, the magnitudes of hydrologic versus temperature changes remain poorly quantified. Here we apply hydrogen isotope analysis (?D) of terrestrial leaf waxes and the TEX86 temperature proxy in sediments from Lake Titicaca to reconstruct hydrologic and temperature variability over the past 50,000 years. Our record reveals that the Altiplano underwent a major climate shift during the last deglaciation, reflected in a ~70-80% enrichment in leaf wax ?D at the onset of the Holocene. Using the global isotope-temperature relationship for meteoric water, only 25-40% of this enrichment can be explained by the 4-5°C deglacial warming shown by the TEX86 proxy, indicating that precipitation was significantly reduced (and evaporation/evapotranspiration increased) during the Holocene. Further, the timing of these hydrologic and temperature changes was asynchronous during the transition from a cold and wet glacial state to a warm and dry Holocene. The major hydrologic shift recorded by leaf wax ?D occurred around ~11-12 ka, consistent with Northern Hemisphere deglacial patterns, whereas TEX86 data indicate that rapid warming began much earlier, more typical of a Southern Hemisphere deglacial pattern. Within the late glacial and Holocene mean climate states, however, there is evidence of synchronous hydrologic and temperature variability on millennial timescales. This study demonstrates that climate on the Altiplano was controlled by the interaction of local and remote forcing on a range of timescales.

Fornace, K.; Shanahan, T. M.; Sylva, S.; Ossolinski, J.; Baker, P. A.; Fritz, S. C.; Hughen, K. A.

2011-12-01

207

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

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

208

The importance of the air temperature variable for the snowmelt runoff modelling using the SRM  

NASA Astrophysics Data System (ADS)

Runoff regimes in most northern basins are controlled by the melting snow cover. A common method for evaluating runoff consists in correlating ambient air temperature and recorded hydrometric gauge values. The air temperature is the principal variable to estimate the importance of the melting of the snow cover when using a global conceptual model such as the snowmelt runoff model (SRM). The temperature, which is often only measured at one weather station, must be extrapolated to the whole basin according to some kind of lapse rate. This extrapolation often assumes that air temperature is representative for a wide region, which is often not the case. The estimation of temperature values is critical, especially for large basins where the surface processes are largely influenced by a forest cover. This project has two objectives: (1) applying a mostly high mountain SRM to the Batiscan River Basin, in the Province of Québec, an area occupied by a forest with a rolling hill topography; (2) investigate the impact of the extrapolation strategy for estimating temperature values and its importance in the runoff modelling. A statistical comparison between the different modelling attempts was performed. This allowed us to obtain a sensitivity analysis of the snow runoff modelling in relation to the extrapolation of the temperature values. Our results showed that the weather station, used to perform the runoff modelling, should be located in the most representative land cover of the study area. Otherwise, the values of a synthetic regional weather station were more reliable for the modelling. Finally, before pursuing any snowmelt modelling with the SRM, the temperature values must be evaluated based on the location of the weather station to see if they are representative of the total study area.

Richard, C.; Gratton, D. J.

2001-12-01

209

Constraints on the temperature inhomogeneity in quasar accretion discs from the ultraviolet-optical spectral variability  

E-print Network

The physical mechanisms of the quasar ultraviolet (UV)-optical variability are not well understood despite the long history of observations. Recently, Dexter & Agol presented a model of quasar UV-optical variability, which assumes large local temperature fluctuations in the quasar accretion discs. This inhomogeneous accretion disc model is claimed to describe not only the single-band variability amplitude, but also microlensing size constraints and the quasar composite spectral shape. In this work, we examine the validity of the inhomogeneous accretion disc model in the light of quasar UV-optical spectral variability by using five-band multi-epoch light curves for nearly 9 000 quasars in the Sloan Digital Sky Survey (SDSS) Stripe 82 region. By comparing the values of the intrinsic scatter $\\sigma_{\\text{int}}$ of the two-band magnitude-magnitude plots for the SDSS quasar light curves and for the simulated light curves, we show that Dexter & Agol's inhomogeneous accretion disc model cannot explain the ...

Kokubo, Mitsuru

2015-01-01

210

Variable-Temperature Rate Coefficients of Proton-Transfer Equilibrium Reaction C2H4 + H3O+  

E-print Network

Variable-Temperature Rate Coefficients of Proton-Transfer Equilibrium Reaction C2H4 + H3O+ C2H5 the observed rate coefficients, a new type of reaction temperature was defined in these studies that considered rate coefficients of this reaction, with molecular beam and ion temperatures varied independently from

Sanov, Andrei

211

Climate-induced variability of sea level in Stockholm: Influence of air temperature and atmospheric circulation  

NASA Astrophysics Data System (ADS)

This study is focused on climate-induced variation of sea level in Stockholm during 1873 1995. After the effect of the land uplift is removed, the residual is characterized and related to large-scale temperature and atmospheric circulation. The residual shows an overall upward trend, although this result depends on the uplift rate used. However, the seasonal distribution of the trend is uneven. There are even two months (June and August) that show a negative trend. The significant trend in August may be linked to fresh water input that is controlled by precipitation. The influence of the atmospheric conditions on the sea level is mainly manifested through zonal winds, vorticity and temperature. While the wind is important in the period January May, the vorticity plays a main role during June and December. A successful linear multiple-regression model linking the climatic variables (zonal winds, vorticity and mean air temperature during the previous two months) and the sea level is established for each month. An independent verification of the model shows that it has considerable skill in simulating the variability.

Chen, Deliang; Omstedt, Anders

2005-09-01

212

North American west coast summer low cloudiness: Broadscale variability associated with sea surface temperature  

NASA Astrophysics Data System (ADS)

Six decades of observations at 20 coastal airports, from Alaska to southern California, reveal coherent interannual to interdecadal variation of coastal low cloudiness (CLC) from summer to summer over this broad region. The leading mode of CLC variability represents coherent variation, accounting for nearly 40% of the total CLC variance spanning 1950-2012. This leading mode and the majority of individual airports exhibit decreased low cloudiness from the earlier to the later part of the record. Exploring climatic controls on CLC, we identify North Pacific Sea Surface Temperature anomalies, largely in the form of the Pacific Decadal Oscillation (PDO) as well correlated with, and evidently helping to organize, the coherent patterns of summer coastal cloud variability. Links from the PDO to summer CLC appear a few months in advance of the summer. These associations hold up consistently in interannual and interdecadal frequencies.

Schwartz, Rachel E.; Gershunov, Alexander; Iacobellis, Sam F.; Cayan, Daniel R.

2014-05-01

213

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

NASA Technical Reports Server (NTRS)

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.

Brown, Stuart; Anand, Lallit

1988-01-01

214

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

NASA Technical Reports Server (NTRS)

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.

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

215

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

NASA Astrophysics Data System (ADS)

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.

D'Arrigo, R.; Wilson, R.

2012-12-01

216

The equatorial Atlantic sea surface temperature variability during the last millennium  

NASA Astrophysics Data System (ADS)

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

Prado, Luciana; Wainer, Ilana; Khodri, Myriam

2014-05-01

217

Using skin temperature variability to quantify surface and subsurface estuarine processes  

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

218

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

NASA Technical Reports Server (NTRS)

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.

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

2005-01-01

219

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

NASA Astrophysics Data System (ADS)

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.

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

1994-07-01

220

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

NASA Astrophysics Data System (ADS)

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.

Bloszies, Chris; Forman, Steven L.

2015-01-01

221

Simultaneous optoacoustic and laser-induced fluorescence studies at variable temperature  

SciTech Connect

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

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

1993-12-31

222

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

NASA Astrophysics Data System (ADS)

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.

Brosseau, C.; Achour, M. E.

2009-06-01

223

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

NASA Astrophysics Data System (ADS)

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.

Paz, Shlomit

2010-05-01

224

Variable pressure and temperature liquid nitrogen cryostat for optical measurements with applied electric fields  

NASA Astrophysics Data System (ADS)

A cryostat with a high-voltage bushing, optical observation ports, variable controlled temperature and pressure has been designed to further the study of liquid nitrogen as a dielectric medium. The novelty in this design lies in the simultaneous achievement of these functions in a single design with a sufficiently large vessel to accommodate realistic geometries for high temperature superconducting power cable termination prototypes. In addition, a commercial single-stage helium expander cryo-cooler is integrated into the apparatus to achieve steady state temperatures down to 63.5 K, without the need for sacrificial loss of liquid nitrogen to maintain vessel temperature. The cryostat inner vessel is certified for operating pressures up to 2 MPa. A custom-made filled-resin bushing provides an electrical feed-through rated to 76.2 kV ac. For optical measurements with a range of sample geometries four optical ports are incorporated into the vessel utilizing sapphire windows and indium seals to form the inner pressure vessel. A technique employing a copper-vapour laser light source and high-speed digital camera for stroboscopic image capture of density change streamers and bubble dynamics with synchronized collection of electrical discharge data has been developed. This design has been used to study pre-breakdown phenomena, bubble dynamics with applied electric fields and electrical breakdown. General construction, mode of operation and initial results are presented.

Swaffield, D. J.; Lewin, P. L.; Chen, G.; Swingler, S. G.

2004-11-01

225

Variability of mesopause temperature from the hydroxyl airglow observations over mid-latitudinal sites, Zvenigorod and Tory, Russia  

NASA Astrophysics Data System (ADS)

We obtained data on temperature in the mesopause vicinity from ground-based observations of the hydroxyl airglow at mid-latitudinal sites, Zvenigorod (56°N, 37°E), located near Moscow, over 2000-2012, and Tory (52°N, 103°E), Eastern Siberia, over 2008-2012. Seasonal behavior of the temperature and its monthly and nightly mean variances are presented. A comparison of the results obtained at two different regions of Russia shows higher values of the mesopause temperature variability in Eastern Siberia. We perform an analysis of the multi-year changes in the temperature variability characteristics based on the Zvenigorod observational data.

Perminov, V. I.; Semenov, A. I.; Medvedeva, I. V.; Zheleznov, Yu. A.

2014-12-01

226

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

E-print Network

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

Sobel, Adam

227

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

NASA Astrophysics Data System (ADS)

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.

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

2009-05-01

228

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

USGS Publications Warehouse

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.

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

2009-01-01

229

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

PubMed

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

Herbert, Ulrike; Albrecht, Antonia; Kreyenschmidt, Judith

2015-03-01

230

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

NASA Astrophysics Data System (ADS)

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

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

2015-03-01

231

Assessing Low Frequency Variability in North Atlantic Ocean Sea Surface Temperatures in Global Climate Models  

NASA Astrophysics Data System (ADS)

The Atlantic Multidecadal Oscillation (AMO) is the leading mode of non-ENSO variability in the surface temperature of the Earth. The AMO mediates sea surface temperatures in the North Atlantic. Thus, its variability produces wavelike variations in the global surface temperature record and thereby alternately masks or amplifies the signal due to enhanced greenhouse gas or aerosol levels. Regionally, it affects the track and intensity of both extratropical cyclones throughout Europe and the Levant and severe tropical cyclones in the North Atlantic basin. See Enfield and Cid-Serrano [2009] for in-depth discussion. Therefore, even if there were no anthropogenic influence on the climate, understanding the dynamics of the AMO and being able to predict it would improve regional climate prediction throughout North America and Europe. In an era of anthropogenic climate change, it is vital that we understand the dynamics of the AMO: in part to predict the oscillations on the general positive trend in global surface temperature and in part because anthropogenic climate change could influence the dynamics and phenomenology of the AMO. Similar anthropogenic modification has been proposed for the El Nino-Southern Oscillation [e.g., Kim et al. 2009]. A small number of ocean and coupled atmosphere/ocean models simulate decadal or multidecadal variability in the North Atlantic, but the exact mechanisms involved vary from model to model. Therefore, characterizing North Atlantic variability on these timescales in a wide range of models opens a broad phase space to falsify mechanisms against a brief and sparse observational record. We have analyzed IPCC AR4 pre-industrial control runs from 23 global climate models (GCMs) in the World Climate Research Programme's (WCRP's) Coupled Model Intercomparison Project phase 3 (CMIP3) multi-model dataset, looking for global sea surface temperature (SST) drift (evidence of a disequilibrated ocean), and North Atlantic SST variability with a spatial pattern and periodicity consistent with instrumental and paleoclimatic records of the AMO. One GCM has been found to be both highly non-drifting and produce a multidecadal oscillation similar to the AMO. One drifting GCM also produces such an oscillation. We will present the full results of this analysis and preliminary results of more in-depth analysis of the “AMOs” simulated by these GCMs, focusing on the impact the processes that drive them could have on instrumental and paleoclimatic archives. D.B. Enfield and L. Cid-Serrano (2009), Secular and multidecadal warmings in the North Atlantic and their relationships with major hurricane activity, Int. J. Climatol., doi: 10.1002/joc.1881. H.-M. Kim, P.J. Webster, and J.A. Curry (2009), Impact of Shifting Patterns of Pacific Ocean Warming on North Atlantic Tropical Cyclones, Science, 325, 77-80.

Heavens, N. G.; Liang, M.; Lin, L.; Li, K.; Tung, K. K.; Yung, Y. L.

2009-12-01

232

Quantifying contributions to the recent temperature variability in the tropical tropopause layer  

NASA Astrophysics Data System (ADS)

The recently observed variability in the tropical tropopause layer, which features an unexpected warming of 1.1 K over the past decade (2001-2011), is investigated with a number of sensitivity experiments from simulations with NCAR's CESM-WACCM chemistry climate model. The experiments have been designed to specifically quantify the contributions from natural as well as anthropogenic factors, such as solar variability (Solar), sea surface temperatures (SSTs), the Quasi-Biennial Oscillation (QBO), stratospheric aerosols (Aerosol), greenhouse gases (GHGs), as well as the dependence on the vertical resolution in the model. The results show that, in the TTL: a cooling in tropical SSTs leads to a weakening of tropical upwelling around the tropical tropopause and hence relative downwelling and adiabatic warming of 0.3 K decade-1; an increased QBO amplitude results in a 0.3 K decade-1 warming; increasing aerosols in the lower stratosphere lead to a 0.4 K decade-1 warming; a prolonged solar minimum and increased GHGs contribute about 0.2 and 0.1 K decade-1 to a cooling, respectively. Two simulations with different vertical resolution show that the vertical resolution can strongly influence the response of the TTL temperature to changes such as SSTs. With higher vertical resolution, an extra 0.6 K decade-1 warming can be simulated through the last decade, compared with results from the "standard" low vertical resolution simulation. Considering all the factors mentioned above, we compute a net 1.3 K decade-1 warming, which is in very good agreement with the observed 1.1 K decade-1 warming over the past decade in the TTL. The model results indicate that the recent warming in the TTL is mainly due to internal variability, i.e. the QBO and tropical SSTs.

Wang, W.; Matthes, K.; Schmidt, T.

2014-08-01

233

Low temperature reveals genetic variability against male-killing Spiroplasma in Drosophila melanogaster natural populations.  

PubMed

Spiroplasma endosymbionts are maternally inherited microorganisms which infect many arthropod species. In some Drosophila species, it acts as a reproductive manipulator, spreading in populations by killing the sons of infected mothers. Distinct Drosophila melanogaster populations from Brazil exhibit variable male-killing Spiroplasma prevalences. In this study, we investigated the presence of variability for the male-killing phenotype among Drosophila and/or Spiroplasma strains and verified if it correlates with the endosymbiont prevalence in natural populations. For that, we analyzed the male-killing expression when Spiroplasma strains from different populations were transferred to a standard D. melanogaster line (Canton-S) and when a common Spiroplasma strain was transferred to different wild-caught D. melanogaster lines, both at optimal and challenging temperatures for the bacteria. No variation was observed in the male-killing phenotype induced by different Spiroplasma strains. No phenotypic variability among fly lines was detected at optimal temperature (23 °C), as well. Conversely, significant variation in the male-killing expression was revealed among D. melanogaster lines at 18.5 °C, probably caused by imperfect transmission of the endosymbiont. Distinct lines differed in their average sex ratios as well as in the pattern of male-killing expression as the infected females aged. Greater variation occurred among lines from one locality, although there was no clear correlation between the male-killing intensity and the endosymbiont prevalence in each population. Imperfect transmission or male killing may also occur in the field, thus helping to explain the low or intermediate prevalences reported in nature. We discuss the implications of our results for the dynamics of male-killing Spiroplasma in natural populations. PMID:24121800

Ventura, Iuri Matteuzzo; Costa, Thais; Klaczko, Louis Bernard

2014-01-01

234

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

NASA Astrophysics Data System (ADS)

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 (?18Osw). Both surface and deep-dwelling species (at the base of the seasonal thermocline) have been measured in order to obtain a complete temperature and ?18Osw 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.

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

2010-12-01

235

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

PubMed

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

Johnstone, James A; Mantua, Nathan J

2014-10-01

236

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

PubMed

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

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

2014-01-01

237

Spatio-Temporal Variability of the North Sea Cod Recruitment in Relation to Temperature and Zooplankton  

PubMed Central

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

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

2014-01-01

238

PMC brightness zonal variability and its correlation with temperature and water vapor  

NASA Astrophysics Data System (ADS)

The correlation between the Polar Mesospheric Cloud (PMC) daily zonal variation and the environmental variables temperature (T) and H2O is investigated using CIPS/AIM albedo, MLS/Aura T and H2O observations, and a 0-D PMC thermodynamic equilibrium model [Hervig et al., 2009]. CIPS measurements cover the entire polar region (> 60°N/S) with an unprecedented spatial resolution of 2 km, and in this study we examine the zonal variability of the albedo on a daily basis. We have chosen 18 longitudinal bins and for each bin a mean albedo north of 70°N is used. The 0-D model is used to assess the relative roles of temperature and H2O in determining the zonal variability of the cloud ice mass density based on an analysis for the 0.00464 hPa pressure surface corresponding to an altitude of ~ 84km, which is the mean northern hemisphere cloud height. Here the ice mass density is used as a proxy to the albedo since both variables reflect the cloud brightness and their horizontal variations are highly similar. Statistics of all days of the five northern seasons from 2007 to 2011 indicate that MLS T and CIPS cloud variation (with scales larger than zonal wave 8-9) are anti-correlated throughout the season, except in the core of the season where the correlation is relatively weak. The cloud and H2O correlation in the zonal direction is generally poor but overall speaking it is slightly positive. The slightly positive correlation implies that more abundant H2O leads to stronger PMCs. Nevertheless, the correlation is overall poor because the H2O depletion from the ice particle formation leads to a systematic phase shift (~50-90 degree in longitude) between the clouds and the measured "post-ice" H2O. Although H2O dominantly controls the cloud brightness variation in the high brightness limit (e.g., >50 ng/m3) [Rong, et al., 2011], T takes on an important role in the weak cloud limit, i.e., when T approaches the frost point. The weak cloud limit applies here because a large percentage of the daily measured cloud events are weak to medium clouds, for example, ~50% in the core of the cloud season. To further examine the role of temperature, we increased MLS T by 5 K uniformly and found substantially stronger correlation of T and cloud variations in the core of the season. This study suggests that temperature takes on a stronger role than H2O in determining the daily PMC zonal variation. It is also implies that, in a statistical sense, the cloud physics described in the 0-D model is sufficient to interpret the daily global cloud brightness variability without critically relying on measurement coincidences and knowledge of dynamics such as waves and wind advection.

Rong, P.; Russell, J. M.; Randall, C. E.; Bailey, S. M.; Lambert, A.

2012-12-01

239

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

NASA Technical Reports Server (NTRS)

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.

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

1987-01-01

240

Improved Monitoring of Inter-annual Temperature Variability Using AIRS/AMSU Observations  

NASA Astrophysics Data System (ADS)

AIRS/AMSU was launched on EOS Aqua in May 2002 and started producing useful data in September 2002. EOS is primarily a mission for studying inter-annual variability of the Earth's surface and atmospheric geophysical parameters for the purpose of improving understanding of climate processes. Surface skin temperature and atmospheric temperature profiles are among many geophysical parameters derived from analysis of AIRS/AMSU observations. The Goddard DAAC had previously analyzed AIRS/AMSU observations starting from September 2002 using the AIRS Science Team Version 4 retrieval algorithm. The AIRS Science Team Version 5 retrieval algorithm became operational at the Goddard DAAC in July 2007 for use in processing AIRS/AMSU data subsequent to that time, and also for reprocessing all the old AIRS/AMSU data. Version 5 contains substantial improvements in capabilities compared to Version 4, especially with regard to improved spatial coverage of retrievals deemed acceptable for generation of climate data sets. These differences in methodology will be briefly described, and results will be shown demonstrating that inter-annual differences of surface and atmospheric temperatures obtained using the Version 5 algorithm are superior to those found in the previous AIRS data record obtained with the Version 4 algorithm.

Susskind, J.; Molnar, G.

2007-12-01

241

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

PubMed

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

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

242

Specific effects of cycling stressful temperatures upon phenotypic and genetic variability of size traits in Drosophila melanogaster  

Microsoft Academic Search

In previous studies, the relationship between developmental temperature and phenotypic or genetic variability has been mainly investigated using different constant temperatures. Natural conditions, however, are characterized by daily thermal cycles, sometimes resulting in a periodic daily stress. Using the isofemale line technique, we examined the effects of daily cycles on body size in two French populations of Drosophila melanogaster. We

G. Pétavy; J. R. David; V. Debat; P. Gibert; B. Moreteau

2004-01-01

243

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

Microsoft Academic Search

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

Anne Dudek Ronan; David E. Prudic; Carl E. Thodal; Jim Constantz

1998-01-01

244

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

PubMed

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

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

2013-11-01

245

Incorporating Patient Breathing Variability into a Stochastic Model of Dose Deposition for  

E-print Network

Incorporating Patient Breathing Variability into a Stochastic Model of Dose Deposition the breathing cycle. Given the maturity of the tech- nology, sensitivity of dose deposition to respiratory day-to-day variability of patient breathing and calculate the resulting stochasticity in dose

Utah, University of

246

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

NASA Astrophysics Data System (ADS)

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.

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

2015-05-01

247

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

NASA Astrophysics Data System (ADS)

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.

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

2011-10-01

248

Seasonal variability of salinity, temperature, turbidity and suspended chlorophyll in the Tweed Estuary.  

PubMed

Results are presented from a campaign of measurements that were undertaken to examine seasonal variability in physical and chemical fluxes and processes within the Tweed Estuary during the period September 1996-August 1997. The study utilised monthly surveys, each of approximately 1 week duration. This article interprets a subset of the salinity, temperature, turbidity [suspended particulate matter (SPM) levels] and chlorophyll a data. Measurements discussed here were obtained throughout the estuary during high-speed transects that covered the region between the tidal river and the coastal zone. Longitudinal distributions of surface salinity depended strongly on freshwater runoff. During high runoff the surface salinity was low and the freshwater-saltwater interface (FSI) was located close to the mouth. The reverse was true at times of low runoff. Salinity stratification was generally strong. During the surveys, river runoff temperatures ranged from approximately 2 to 18 degrees C and coastal waters (approximately 33 salinity) from approximately 6 to 15 degrees C. Turbidity was low throughout the campaign (SPM < 30 mg l(-1)). Because of rapid flushing times (one or two tides), turbidity tended to mix conservatively between river and coastal waters. Higher coastal turbidity was associated with stronger wind events, and higher fluvial turbidity with spate events. Suspended chlorophyll a levels were usually low throughout the estuary (typically < 2 microg l(-1)) and showed large spatial variability. Because of the rapid flushing of the estuary, it is hypothesised that it was not possible for several algal cell divisions to occur before algae were flushed to the coastal zone. A 'bloom' occurred during the May 1997 survey, when chlorophyll a levels reached 14 microg l(-1). Higher chlorophyll a concentrations at that time occurred at very low salinities, indicating that these waters and algae were largely fluvially derived, and may have resulted from increasing springtime solar irradiation. PMID:10847156

Uncles, R J; Bloomer, N J; Frickers, P E; Griffiths, M L; Harris, C; Howland, R J; Morris, A W; Plummer, D H; Tappin, A D

2000-05-01

249

Long-term response of stratospheric ozone and temperature to solar variability  

NASA Astrophysics Data System (ADS)

The long-term variability in stratospheric ozone mass mixing ratio (O3) and temperature (T) from 1979 to 2013 is investigated using the latest reanalysis product delivered by the European Centre for Medium-Range Weather Forecasts (ECMWF), i.e., ERA-Interim. Moreover, using the Mg II index time series for the same time period, the response of the stratosphere to the 11-year Schwabe solar cycle is investigated. Results reveal the following features: (i) upward (downward) trends characterize zonally averaged O3 anomalies in the upper (middle to lower stratosphere) stratosphere, while prevailing downward trends affect the T field. Mg II index data exhibit a weaker 24th solar cycle (though not complete) when compared with the previous two; (ii) correlations between O3 and Mg II, T and Mg II, and O3 and T are consistent with photochemical reactions occurring in the stratosphere and large-scale transport; and (iii) wavelet cross-spectra between O3 and Mg II index show common power for the 11-year period, particularly in tropical regions around 30-50 hPa, and different relative phase in the upper and lower stratosphere. A comprehensive insight into the actual processes accounting for the observed correlation between ozone and solar UV variability would be gained from an improved bias correction of ozone measurements provided by different satellite instruments, and from the observations of the time behavior of the solar spectral irradiance.

Bordi, I.; Berrilli, F.; Pietropaolo, E.

2015-03-01

250

Response of El Niño sea surface temperature variability to greenhouse warming  

NASA Astrophysics Data System (ADS)

The destructive environmental and socio-economic impacts of the El Niño/Southern Oscillation (ENSO) demand an improved understanding of how ENSO will change under future greenhouse warming. Robust projected changes in certain aspects of ENSO have been recently established. However, there is as yet no consensus on the change in the magnitude of the associated sea surface temperature (SST) variability, commonly used to represent ENSO amplitude, despite its strong effects on marine ecosystems and rainfall worldwide. Here we show that the response of ENSO SST amplitude is time-varying, with an increasing trend in ENSO amplitude before 2040, followed by a decreasing trend thereafter. We attribute the previous lack of consensus to an expectation that the trend in ENSO amplitude over the entire twenty-first century is unidirectional, and to unrealistic model dynamics of tropical Pacific SST variability. We examine these complex processes across 22 models in the Coupled Model Intercomparison Project phase 5 (CMIP5) database, forced under historical and greenhouse warming conditions. The nine most realistic models identified show a strong consensus on the time-varying response and reveal that the non-unidirectional behaviour is linked to a longitudinal difference in the surface warming rate across the Indo-Pacific basin. Our results carry important implications for climate projections and climate adaptation pathways.

Kim, Seon Tae; Cai, Wenju; Jin, Fei-Fei; Santoso, Agus; Wu, Lixin; Guilyardi, Eric; An, Soon-Il

2014-09-01

251

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

PubMed

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

Gwatirisa, Pauline; Manderson, Lenore

2012-01-01

252

A naturalistic enquiry into the day-to-day lives of obese children  

Microsoft Academic Search

Childhood obesity has reached epidemic levels in both developed and developing countries, posing one of the greatest challenges to paediatric health in the 21st century. To date, interventions to prevent and treat child obesity have had moderate success, with many researchers advocating the need for individual and community programs combined with a better understanding of the contextual factors affecting children,

Lauren M Puglisi

2009-01-01

253

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

ERIC Educational Resources Information Center

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…

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

254

INTRODUCTION Health care providers face many challenges in the day to day pursuit of  

E-print Network

, medical student, physicians assistant or nurse practitioner ­ and no matter what their level of skill) Give Guidance About Errors and Omissions 5) Teach a General Principle 6) Conclusion #12;4 orally. She

Gilbert, Matthew

255

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

Microsoft Academic Search

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,

Pauline Gwatirisa; Lenore Manderson

2012-01-01

256

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)

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.

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

2014-10-01

257

Mg/Ca Ratios in Coralline Red Algae as Temperature Proxies for Reconstructing Labrador Current Variability  

NASA Astrophysics Data System (ADS)

Marine ecosystems and fishery productivity in the Northwestern Atlantic have been considerably affected by regional climate and oceanographic changes. Fluctuations of North Atlantic marine climate have been linked in part to a dominant pattern of atmospheric circulation known as the North Atlantic Oscillation, which has a strong influence on transport variability of the Labrador Current (LC). The cold LC originates in the Labrador Sea and flows southbound along the Eastern Canadian coastline causing an important cooling effect on marine waters off the Canadian Atlantic provinces. Although interdecadal and interannual variability of sea surface temperatures (SST) in the LC system have been documented, a long-term pattern has not been identified. In order to better understand the observed ecosystem changes and their relationship with climate variability in the Northwestern Atlantic, a century-scale reconstruction of spatial and temporal variations of the LC is needed. This, however, requires reliable long-term and high-resolution SST records, which are not available from short instrumental observations. Here we present the first century-scale SST reconstructions from the Northwest Atlantic using long-lived coralline red algae. Coralline red algae have a high-Mg calcite skeleton, live in shallow water worldwide and develop annual growth bands. It has previously been demonstrated that subannual resolution SSTs can be obtained from coralline red algal Mg/Ca ratios, a commonly used paleotemperature proxy. Specimens of the long-lived coralline red algae Clathromorphum compactum were collected alive in August 2008 along a latitudinal transect spanning the southern extent of LC flow in Nova Scotia and Newfoundland. This collection is supplemented with specimens from the same region collected in the 1960's. In order to reconstruct spatial and temporal patterns of the LC, selected samples of C. compactum were analyzed for Mg/Ca using Laser Ablation Inductively-Coupled Plasma Mass Spectrometry (LA-ICP-MS). Mg/Ca ratios range from 0.048 to 0.138 (measured in weight %) and relate to water temperatures of -1 to 16°C. Age models were established by comparing annual growth increments (average increment width 350 microns/year) with Mg/Ca cycles. This yielded subannually-resolved Mg/Ca-based SST reconstructions spanning the past century.

Gamboa, G.; Hetzinger, S.; Halfar, J.; Zack, T.; Kunz, B.; Adey, W.

2009-05-01

258

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

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

259

Variable Temperature Waveguide Load for Measurements of Cryogenic Millimeter-wave Detectors  

NASA Astrophysics Data System (ADS)

We would like to measure the microwave response of superconducting transition-edge (TES) detectors intended to measure polarization in the Cosmic Microwave Background (CMB). We have constructed a variable temperature (4-20K) load to simulate the blackbody radiation of the CMB as well as emission from optics, and the atmosphere and couple it efficiently to the detector. The load is a Nichrome plated quartz wafer inserted into a waveguide. The wafer is heated by applying Joule power to an attached resistor. We measured the temperature of the load using a Germanium resistance thermometer. In our study we measured the thermal time constant of the wafer (the time to reach equilibrium when there is a change in the power applied to the load), and the heat capacity and thermal conductance to a 4K bath. Our goals in construction were to minimize the size of the load, ensure that it is at least 90% emissive, and to optimize the thermal isolation of the load in order to minimize the amount of applied power while also obtaining a reasonable time constant. We discuss the design, construction and test results for this device. This work was supported by the National Science Foundation's REU program and the Department of Defense's ASSURE program through NSF Award AST-0453442.

Abdulla, Zubair; Barrentine, E.; Timbie, P.

2009-01-01

260

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

NASA Technical Reports Server (NTRS)

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.

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

2012-01-01

261

Siberian high variability and its teleconnections with tropical circulations and surface air temperature over Saudi Arabia  

NASA Astrophysics Data System (ADS)

Based on a generated time series for the central pressure of the Siberian High, and on defining a robust Siberian High Index (SHI), the behavior of this atmospheric center of action is examined from 1949 to 2010 with regard to inter-annual variations, persistence, trends, abrupt changes, spectral analysis and interactions. The interannual variability in the central pressure of the Siberian High is considerable. The mean downward linear and non-linear trend over the entire period (1949-2010) is estimated and is found to be statistically significant at the 95 % confidence level. Low frequency variation and linearity within the SHI time series are found from the persistence analysis. Using spectral analysis, the center of action of the Siberian High is characterized by non-periodic behavior; the peaks occur only at the lowest frequency and may be related to the Sea Surface Temperature (SST) over the El Niño region. The Siberian High is affected by the Hadley circulation cell; there is no detectable connection between the Walker circulation cell and the Siberian High. SSTs over the El Niño region may affect the Siberian High. Interactions between the Siberian High and the SSTs over the tropical Atlantic Ocean are absent. The SHI is positively correlated to surface air temperatures over Saudi Arabia, and this is statistically significant in the western and north-western regions.

Hasanean, H. M.; Almazroui, M.; Jones, P. D.; Alamoudi, A. A.

2013-10-01

262

Winter mean temperature variability in Turkey associated with the North Atlantic Oscillation  

NASA Astrophysics Data System (ADS)

Changes and variability in seasonal average mean and monthly mean winter (DJF) air temperature series at 70 stations of Turkey and the circulation types at 500-hPa geopotential height level were investigated to explain atmospheric controls of temperature variations during the extreme (weak and strong) phases and normal (negative and positive) phases of the North Atlantic Oscillation (i.e., Ponta Delgada-Reykjavik and the Gibraltar-Reykjavik) indices. During the positive phases of the North Atlantic Oscillation indices (NAOIs), northeasterly circulation increased, and thus spatially coherent and significant cold signals dominate over the majority of Turkey. This pattern is closely linked to anomalously low 500-hPa heights over the region of the Icelandic Low, and anomalously high geopotential heights over the regions of the Azores High, the western Mediterranean basin and the Europe, in general including the Balkans and northwest Turkey. Contrarily, during the negative phases of the NAOIs, prevailing westerly winds that originate from the subtropical northeast Atlantic increase, and thus spatially coherent and significant warm signals over the Anatolian peninsula appear. This pattern is closely linked to the increased cyclonic activity and associated increased westerly and southwesterly circulation causing warm maritime air advection over the Mediterranean basin toward Turkey.

Türke?, Murat; Erlat, Ecmel

2009-09-01

263

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

NASA Technical Reports Server (NTRS)

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.

Gary, Bruce L. (Inventor)

2001-01-01

264

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

USGS Publications Warehouse

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.

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

2009-01-01

265

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

NASA Astrophysics Data System (ADS)

SummaryAt 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.

Giraldo, Mario A.; Bosch, David; Madden, Marguerite; Usery, Lynn; Finn, Michael

2009-04-01

266

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

NASA Astrophysics Data System (ADS)

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

Fernandez, I.; Villanoy, C. L.

2013-12-01

267

Variability in precipitation, temperature and river runoff in W Central Asia during the past ~ 2000 yrs  

NASA Astrophysics Data System (ADS)

The tributary rivers Amu Darya and Syr Darya contribute major amounts of water to the hydrological budget of the endorheic Aral Sea. Processes controlling the flow of water into rivers in the headwater systems in Tien Shan (Kyrgyzstan) and Pamir (Tajikistan) are therefore most relevant. Lake water mineralization is strongly dependent on river discharge and has been inferred from spectrometrically determined gypsum and other salt contents. Comparison of high-resolution mineralization data with tree ring data, other proxies for tracing temperature and snow cover in NW China, and accumulation rates in the Guliya Ice Core indicate that mineralization over the past ~ 2000 yrs in the Aral Sea reflects snow cover variability and glacier extent in Tien Shan and Pamir (at the NW and W edges of the Tibetan Plateau). Snow cover in W Central Asia is preferentially a winter expression controlled by temperature patterns that impact the moisture-loading capacity over N Europe and NW Asia (Clark et al., 1999). We observed that the runoff, resulting from warmer winter temperatures in W Central Asia and resulting in a reduction of snow cover, decreased between AD 100-300, AD 1150-1250, AD 1380-1450, AD 1580-1680 and during several low frequency events after AD 1800. Furthermore, we observed a negative relationship between the amount of mineralization in the Aral Sea and SW summer monsoon intensity starting with the Little Ice Age. Based on these observations, we conclude that the lake level changes during the past ~ 2000 yrs were mostly climatically controlled. Around AD 200, AD 1400 and during the late 20th century AD, human activities (namely irrigation) may also have synergistically influenced discharge dynamics in the lower river courses.

Oberhänsli, Hedi; Novotná, Kate?ina; Píšková, Anna; Chabrillat, Sabine; Nourgaliev, Danis K.; Kurbaniyazov, Abilgazy K.; Matys Grygar, Tomáš

2011-03-01

268

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

NASA Astrophysics Data System (ADS)

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.

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

2015-01-01

269

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

NASA Astrophysics Data System (ADS)

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

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

1988-10-01

270

Inter-Decadal to Multi-Decadal Sea Surface Temperature Variability in the Southwest Tropical Pacific Since AD 1648  

Microsoft Academic Search

The southwest tropical Pacific is a region with temporally and spatially sparse sea surface temperature (SST) records that limit investigations of climate variability on interannual to centennial time scales for this region. We present a monthly resolved coral Sr\\/Ca record from 1648 to 1999 from Amédée Island, New Caledonia (22.48°S, 166.47°E), and reconstruct SST variability in the southwest Pacific for

K. L. Delong; T. M. Quinn; F. W. Taylor; K. Lin; C. Shen

2008-01-01

271

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

NASA Astrophysics Data System (ADS)

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.

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

2015-02-01

272

Temporal Variability of Precipitation and Temperature across Heinrich Events from Bahamian Stalagmites  

NASA Astrophysics Data System (ADS)

During the last glacial period there is substantial evidence for global variability in climate dominated by Heinrich and Dansgaard-Oeschger events. Heinrich events have been shown to correlate with rapid climate change such as cooling in the North Atlantic, precipitation decrease in Africa and Asia and warming in Antarctica. While a comprehensive picture of climate patterns is emerging, the climate in the topical Atlantic is still not as well understood. In this study, a stalagmite from the Bahamas has been analyzed for carbon and oxygen isotopes and fluid inclusion isotopic analysis across Heinrich events 1-3. The combination of both methodologies allows for the determination of the temporal drip water isotopic variability and in addition the temperature at the time of formation. The stalagmites were dated using U/Th and analyzed for stable carbon and oxygen isotopes at a resolution of 20 ?m (approximately one sample every 2 years). Fluid inclusion analyses were conducted at a resolution of about 1.5 cm. Fluid inclusion analysis is the analysis of microscopic, water filled cavities within the stalagmite. These cavities preserve drip water at the time of formation and allow for the measurement of the ?18O composition of the formation water. In the subtropics, it has been demonstrated that higher volume rainfall events generally leads to a depleted ?18O and ?13C signal, whereas heavier ?18O and ?13C values are attributed to lower amounts of rainfall. The fluid inclusion data help constrain the origin of the large changes in the oxygen isotopic composition of the speleothem itself across the Heinrich events, which averages about 4 % for C and 2 % for O for Heinrich events 1-3. These results may support a rapid shift from an arid and colder to a much wetter and warmer climate in the Bahamas associated with Heinrich events.

Arienzo, M.; Swart, P. K.; Vonhof, H. B.; Broad, K.; Clement, A. C.; Eisenhauer, A.; Kakuk, B.

2011-12-01

273

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

NASA Technical Reports Server (NTRS)

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.

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

2000-01-01

274

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

E-print Network

VARIABLE-TEMPERATURE SOLID-STATE NMR STUDIES OF IRON(II) AND IRON(III) COMPLEXES A Thesis by PATRICIA ARLENE SHEPARD Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree... of MASTER OF SCIENCE August 1989 Major Subject: Chemistry VARIABLE-TEMPERATURE SOLID-STATE NMR STUDIES OF IRON(II) AND IRON(III) COMPLEXES A Thesis by PATRICIA ARLENE SHEPARD Approved as to style and content by: g, ( James F. Haw (Chair...

Shepard, Patricia Arlene

1989-01-01

275

Climate Variability in the Andes of Ecuador and Its Relation to Tropical Pacific and Atlantic Sea Surface Temperature Anomalies  

Microsoft Academic Search

The main spatiotemporal modes of seasonal precipitation and temperature variability in the Andes of Ecuador (1°N-4°S) and their relation to tropical Pacific and Atlantic sea surface temperature anomalies (SSTAs) between 1963-92 are identified based on rotated principal component analysis and cross-correlation techniques. Outgoing longwave radiation composites are analyzed during periods of strong oceanic forcing to confirm the proposed physical mechanisms.

Mathias Vuille; Raymond S. Bradley; Frank Keimig

2000-01-01

276

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)

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.

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

1977-01-01

277

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

Microsoft Academic Search

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

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

2011-01-01

278

Power density analysis and optimization of a regenerated closed variable-temperature heat reservoir Brayton cycle  

NASA Astrophysics Data System (ADS)

In this paper, the power density, defined as the ratio of power output to the maximum specific volume in the cycle, is taken as the objective for performance analysis and optimization of an irreversible regenerated closed Brayton cycle coupled to variable-temperature heat reservoirs from the viewpoint of finite time thermodynamics (FTT) or entropy generation minimization (EGM). The analytical formulae about the relations between power density and pressure ratio are derived with the heat resistance losses in the hot- and cold-side heat exchangers and the regenerator, the irreversible compression and expansion losses in the compressor and turbine, the pressure drop losses at the heater, cooler and regenerator as well as in the piping, and the effect of the finite thermal capacity rate of the heat reservoirs. The obtained results are compared with those results obtained by using the maximum power criterion, and the advantages and disadvantages of maximum power density design are analysed. The maximum power density optimization is performed in two stages. The first is to search the optimum heat conductance distribution corresponding to the optimum power density among the hot- and cold-side heat exchangers and the regenerator for a fixed total heat exchanger inventory. The second is to search the optimum thermal capacitance rate matching corresponding to the optimum power density between the working fluid and the high-temperature heat source for a fixed ratio of the thermal capacitance rates of two heat reservoirs. The influences of some design parameters, including the effectiveness of the regenerator, the inlet temperature ratio of the heat reservoirs, the effectiveness of the heat exchangers between the working fluid and the heat reservoirs, the efficiencies of the compressor and the turbine, and the pressure recovery coefficient, on the optimum heat conductance distribution, the optimum thermal capacitance rate matching, and the maximum power density are provided by numerical examples. The power plant design with optimization leads to a smaller size including the compressor, turbine, and the hot- and cold-side heat exchangers and the regenerator. When the heat transfers between the working fluid and the heat reservoirs are carried out ideally, the pressure drop loss may be neglected, and the thermal capacity rates of the heat reservoirs are infinite, the results of this paper then replicate those obtained in recent literature.

Chen, Lin-, Gen; Zheng, Jun-Lin; Sun, Feng-Rui; Wu, Chih

2001-06-01

279

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...

280

Annual and interannual variability of Atlantic Water temperatures in the Norwegian and Barents Seas: 1980–1996  

Microsoft Academic Search

Changes in the oceanographic climate of the Arctic Ocean during the 1990s have been linked to anomalous heat and volume transports of Atlantic Water (AW) from the Nordic Seas. This paper focuses on the variability in the AW temperature in the Norwegian Sea and in the Barents Sea Opening (BSO), using 16 years of data from five regular hydrographic sections

Tore Furevik

2001-01-01

281

A simplified black-box model oriented to chilled water temperature control in a variable speed vapour compression system  

Microsoft Academic Search

The aim of this work is to propose a black-box model to accurately predict the chilled water temperature dynamic response of a vapour compression chiller. The model is oriented to be of value in determining an adequate control algorithm based on compressor speed regulation. The model uses variables that are easily obtained in any commercial or industrial facility, such as

J. A. Romero; J. Navarro-Esbrí; J. M. Belman-Flores

2011-01-01

282

Multidecadal North Atlantic Sea Surface Temperature and Atlantic Meridional2 Overturning Circulation Variability in CMIP5 Historical Simulations3  

E-print Network

from the South55 Atlantic and tropical North Atlantic to the subpolar and polar North Atlantic, where1 Multidecadal North Atlantic Sea Surface Temperature and Atlantic Meridional2 Overturning Circulation Variability in CMIP5 Historical Simulations3 4 Liping Zhang 1 & 2 5 Chunzai Wang 2 6 7 8 1

283

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

Microsoft Academic Search

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

Sharon E. Nicholson; Dara Entekhabi

1987-01-01

284

Modeling temporal and large-scale spatial variability of soil respiration from soil water availability, temperature and vegetation productivity indices  

Microsoft Academic Search

Field-chamber measurements of soil respiration from 17 different forest and shrubland sites in Europe and North America were summarized and analyzed with the goal to develop a model describing seasonal, interannual and spatial variability of soil respiration as affected by water availability, temperature, and site properties. The analysis was performed at a daily and at a monthly time step. With

Markus Reichstein; Ana Rey; Annette Freibauer; John Tenhunen; Riccardo Valentini; Joao Banza; Pere Casals; Yufu Cheng; Jose M. Grünzweig; James Irvine; Richard Joffre; Beverly E. Law; Denis Loustau; Franco Miglietta; Walter Oechel; Jean-Marc Ourcival; Joao S. Pereira; Alessandro Peressotti; Francesca Ponti; Ye Qi; Serge Rambal; Mark Rayment; Joan Romanya; Federica Rossi; Vanessa Tedeschi; Giampiero Tirone; Ming Xu; Dan Yakir

2003-01-01

285

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

PubMed Central

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

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

286

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

ERIC Educational Resources Information Center

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…

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

2007-01-01

287

Multidecadal Ocean Temperature and Salinity Variability in the Tropical North Atlantic: Linking with the AMO, AMOC, and Subtropical Cell  

E-print Network

Multidecadal Ocean Temperature and Salinity Variability in the Tropical North Atlantic: Linking (AMO) is characterized by the sea surface warming (cooling) of the entire North Atlantic during its warming (cooling) and a subsurface cooling (warming) in the tropical North Atlantic (TNA). It is further

Wang, Chunzai

288

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

Microsoft Academic Search

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

A. Mawire; M. McPherson

2009-01-01

289

A 28-ka history of sea surface temperature, primary productivity and planktonic community variability in the western Arabian Sea  

Microsoft Academic Search

Uranium series radionuclides and organic biomarkers, which represent major groups of planktonic organisms, were measured in western Arabian Sea sediments that span the past 28 ka. Variability in the past strength of the southwest and northeast monsoons and its influence on primary productivity, sea surface temperature (SST), and planktonic community structure were investigated. The average alkenone-derived SST for the last

Ali Pourmand; Franco Marcantonio; Thomas S. Bianchi; Elizabeth A. Canuel; Elizabeth J. Waterson

2007-01-01

290

Ultrahigh-vacuum variable-temperature scanning tunneling microscopy: Surface reactions and molecular ordering  

NASA Astrophysics Data System (ADS)

This thesis describes the design, construction, and application of a new ultra high vacuum (UHV) chamber, equipped with Auger electron spectroscopy (AES), low energy electron diffraction (LEED), quadrupole mass spectrometer (QMS), argon ion sputtering gun, and a variable temperature scanning tunneling microscope (VT-STM). In this system, a novel procedure is introduced for transferring a sample off a conventional UHV sample manipulator and onto the microscope, without disconnecting the heating or thermocouple wires. The microscope, a modified version of the Besocke beetle microscope, is mounted on a 2.75" OD UHV flange and is directly attached to the base of the chamber. The sample is attached to a tripod sample holder, that is held by the main manipulator for AES, LEED, and sputtering experiments. The tripod sample holder can be removed from the main manipulator and placed onto the STM. The VT-STM has the capability of acquiring images between the temperature range of 200--400K. A detailed description of the chamber and the sample transfer is described in chapter 1. The performance of the chamber is demonstrated by performing a series of experiments. It has been demonstrated that argon ion sputtering of a Pt(111) sample held at an elevated temperature, one layer deep island vacancies are created. In chapter 2, it will be shown that by controlling the surface temperature, over the range of 625 K to 775 K, it is possible to control the size of these vacancies over the range of 30 A to 400 A. The VT-STM is used to quantify the formation of the island vacancies. In addition, the STM was also used to investigate the dehydrogenation of a series of mono-olefins on Pt(111) to form carbon particles at 700 K. The carbon particles were formed both on a clean, annealed, and on sputtered Pt(111) surfaces. The details of those experiments are in chapters 3 and 4. The carbon particles are randomly distributed over the surface, and show no preference for formation at particular surface features such as step edges. Also, the formation of the carbon particles is not influenced by large monolayer vacancy islands. However, on a surface where smaller vacancy islands have been formed, the carbon particles show a preference of forming on the terraces and not inside of the small vacancy islands. The difference in behavior between large vacancy islands and small vacancy islands (d ? 40 A) can be explained if molecular diffusion across steps is slow and dehydrogenation products initially decorate the walls (steps) of the vacancy islands. We have also studied the impact of sputtering the sample prior to olefin adsorption with the incident ion beam at an angle away from the surface normal. The carbon particles formed on such surfaces are highly spatially aligned.

Nafisi, Kourosh

291

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

PubMed

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

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

2014-01-01

292

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

PubMed Central

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

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

2014-01-01

293

Mechanisms of Summertime Subtropical Southern Indian Ocean Sea Surface Temperature Variability: The Importance of Atmospheric Water Vapor Transport  

NASA Astrophysics Data System (ADS)

It is well known that some warm season subtropical Indian Ocean sea surface temperature (SST) variability correlates with rainfall over certain regions of Africa that depend on rainfall for their economic well being. This SST variability is known to have a distinctive basin-scale pattern that is also observed in latent heat flux variability. Recent studies have determined that this SST variability is at least partially driven by latent heat flux, but the processes that create this latent heat flux variability have not been fully described. Previously, it has been hypothesized that wind speed variations drive this latent heat flux variability. Here, the mechanism that drives this heat flux/SST variability is determined from analyses of operational air-sea fluxes, ocean mixed layer modeling and simple atmospheric boundary layer physics. Results confirm that this SST variability is predominantly driven by latent heat flux variability, but show that this latent heat flux variability is mainly driven by near surface humidity anomalies, rather than wind speed anomalies. Results also show that these humidity anomalies are fundamentally driven by the advection of the climatological humidity field by near surface meridional wind anomalies. It is shown that the pertinent wind anomalies occur when the subtropical atmospheric anticyclone is preferentially located to one side of the basin. Although the timescale of air-sea interaction is not an intrinsic part of the mechanism described here, it is notable that the details of this process is often obscured in seasonal or longer term averages. For instance, the magnitudes of the monthly latent heat anomalies described here are up to an order of magnitude larger than the multi-seasonal anomalies that have previously been reported to be associated with these phenomena. The mechanism described here implies that Atmospheric Model Intercomparison Project (AMIP) style models, such as those that may be used for rainfall prediction, will integrate surface heat flux anomalies of the wrong sign over much, but not all of the lifecycle of these SST anomalies.

Chiodi, A. M.; Harrison, D. E.

2006-12-01

294

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

NASA Astrophysics Data System (ADS)

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

Castelao, Renato M.; Wang, Yuntao

2014-03-01

295

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

Microsoft Academic Search

The remarkably sensitive temperature dependence of the207Pb 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

ANTHONY BIELECKI; DOUGLAS P. BURUM

1995-01-01

296

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

SciTech Connect

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.

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

2009-12-21

297

Stream Temperature Variability as an Indicator of Groundwater-Surface Water Interactions in Two Groundwater-Fed Streams  

NASA Astrophysics Data System (ADS)

Water temperature can be a useful tool in assessing the nature and the locations of groundwater - surface water interactions, particularly during low flow periods. In this study, a network of forty calibrated temperature (TidBit) loggers was installed in two groundwater-fed streams (Fishtrap and Bertrand Creeks) in the Lower Fraser Valley of British Columbia and northern Washington State. These streams have precipitation-driven flow regimes and are presumed to be sustained by baseflow during the annual low-flow period which lags minimum precipitation by approximately one month. In these particular streams, understanding groundwater-surface water interactions has been identified data gap in the development of recovery strategies for maintaining ecosystem health and habitat for two endangered fish species, the Nooksack Dace and Salish Sucker. From July 2008 to June 2009, stream temperature and discharge, groundwater temperature and level, and climate were monitored consecutively over two low-flow seasons with the objective of quantifying the spatial and temporal variability within each stream, as well as differences and trends between the streams. The temperature logger networks were installed over 50 m of channel or less at one site on each stream, as well as at two additional sites on Fishtrap Creek for regional coverage. Within each stream, the network of temperature loggers showed the variability in water temperature over a short distance of the channel. In Fishtrap Creek, among 15 dataloggers, the mean variability was 1.3oC, and in Bertrand Creek, among 19 dataloggers, the mean variability was 0.7oC. Fishtrap Creek water temperature ranged from 0.4oC to 17.6oC, showing less variability than Bertrand Creek, which ranged from -0.1oC to 20.8oC. The groundwater temperatures remained relatively stable throughout the year and ranged from 10.1oC to 12.0oC. Fishtrap Creek water temperature patterns were generally stable and mimicked groundwater temperature variations, consistent with a greater groundwater input. In contrast, Bertrand Creek water temperature patterns resembled the variability in the air temperatures, which ranged from -7.7oC to 32.4oC, with daily and seasonal fluctuations. The different responses in the stream suggest that stream morphology, riparian cover and/or surficial geology/land use are influencing timing and magnitude of the groundwater-surface water interactions. Fishtrap Creek has limited riparian cover and is situated in heterogeneous coarse grained surficial deposits. In contrast, Bertrand Creek has well developed riparian cover and is situated in a fine grained, low conductivity surficial geology unit. Despite the lack of riparian cover, which generally buffers water temperatures, Fishtrap Creek was found to have a generally stable water temperature regime relative to Bertrand Creek. The results suggest that the surficial geology of each stream exerts a greater influence on the groundwater-surface water interactions than do the riparian cover and land use patterns.

Middleton, M.; Allen, D. M.

2009-12-01

298

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

NASA Astrophysics Data System (ADS)

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.

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

2014-03-01

299

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

NASA Astrophysics Data System (ADS)

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 ?18O 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.

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

300

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

NASA Astrophysics Data System (ADS)

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

Butterfield, D.; Gardiner, T.

2015-01-01

301

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

NASA Astrophysics Data System (ADS)

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 ?18O 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 ?18O 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 ?18O values to calculate past ?18Oseawater 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 ?18Oseawater 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).

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

2009-12-01

302

Increased winter soil temperature variability enhances nitrogen cycling and soil biotic activity in temperate heathland and grassland mesocosms  

NASA Astrophysics Data System (ADS)

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.

Schuerings, J.; Jentsch, A.; Hammerl, V.; Lenz, K.; Henry, H. A. L.; Malyshev, A. V.; Kreyling, J.

2014-12-01

303

Climate Variability in the Andes of Ecuador and Its Relation to Tropical Pacific and Atlantic Sea Surface Temperature Anomalies.  

NASA Astrophysics Data System (ADS)

The main spatiotemporal modes of seasonal precipitation and temperature variability in the Andes of Ecuador (1°N-4°S) and their relation to tropical Pacific and Atlantic sea surface temperature anomalies (SSTAs) between 1963-92 are identified based on rotated principal component analysis and cross-correlation techniques. Outgoing longwave radiation composites are analyzed during periods of strong oceanic forcing to confirm the proposed physical mechanisms. Despite the close proximity to the Pacific, precipitation variability in the Andes of Ecuador is not related to SSTA in the tropical Pacific domain alone. The El Niño-Southern Oscillation influence is most dominant in the northwestern part of the Andes during December-February (DJF) and in the eastern Cordillera during June-August (JJA) and in both cases associated with below- (above-) average precipitation during El Niño (La Niña) years. During most of the year precipitation variability over the eastern Andes is related to a dipolelike correlation structure in the tropical Atlantic, featuring positive correlations with SSTA to the south of the ITCZ and negative correlations to the north. The proposed mechanism involves positive SSTA in the tropical South Atlantic and contemporaneous negative SSTA in the tropical North Atlantic, resulting in increased rainfall over the eastern Cordillera. The only region with slightly increased precipitation during El Niño events is confined to a narrow area along the western Andean slope between 1° and 3°S in close proximity to the Pacific. However, this relationship is weak and only apparent in DJF. Temperature variability in the Andes can largely be explained by SSTA in the tropical Pacific domain. The temperature response closely follows SSTA in the Niño-3 and Niño-3.4 regions with approximately one-month lag. The northernmost part of the Andes (north of 0.5°N) is the only region where temperatures are significantly correlated with tropical North Atlantic SSTA.

Vuille, Mathias; Bradley, Raymond S.; Keimig, Frank

2000-07-01

304

Temperature and precipitation drive temporal variability in aquatic carbon and GHG concentrations and fluxes in a peatland catchment.  

PubMed

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

Dinsmore, K J; Billett, M F; Dyson, K E

2013-07-01

305

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

SciTech Connect

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.

Hanrahan, Timothy P.

2007-02-01

306

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

NASA Technical Reports Server (NTRS)

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.

Yang, Fanglin; Lau, K.-M.

2004-01-01

307

Impact of variable reservoir releases on management of downstream water temperatures  

Microsoft Academic Search

A coupled unsteady flow and heat transport model is used to determine the impacts of fluctuating reservoir releases on downstream water temperatures. Maintenance of stream temperatures is one of the most common reasons cited for imposition of minimum flow requirements in regulated (reservoir controlled) rivers. Minimum flow constraints for temperature control are typically developed using worst-case scenarios (i.e., maximum air

John C. Carron; Harihar Rajaram

2001-01-01

308

Sensitivity of frost occurrence to temperature variability in the European Alps  

Microsoft Academic Search

In this study, we set out to investigate the linkage of frost frequency to monthly mean temperature and its sensitivity to temperature changes. According to other related studies, the linkage between frost frequency and monthly mean temperature is approximated month per month via hyperbolic tangent functions. These models are validated using three validation experiments including split sample tests and temporal

Ingeborg Auer; Christoph Matulla; Reinhard Böhm; Markus Ungersböck; Maurizio Maugeri; Teresa Nanni; Rossella Pastorelli

2005-01-01

309

Long-term trend and multi-annual variability of water temperature in the pristine Bela River basin (Slovakia)  

NASA Astrophysics Data System (ADS)

SummaryBiological processes in surface waters appreciably depend on temperature of water. This paper summarizes our investigations of water temperature in the Bela River. The Bela River is a mountainous stream not influenced by direct human activities, draining the headwaters of the Vah River basin in the Tatra National Park (TANAP), Slovakia. Our primary aim was to identify the long-term trends and multi-annual variability of the annual water temperature at the Podbanske gauging station, using temperature readings taken at 7.00 am for the period of 50 years (1959-2008). Long-term mean of the annual water temperature of the Bela River at the Podbanske gauging station (922 m a.s.l.) was 4.2 °C, the air temperature at Podbanske meteorological station (972 m a.s.l.) was 5.0 °C. Both, air and water temperature, show an increasing trend. While the air temperature within 50-years increased significantly by 1.5 °C, in the case of water temperature this increase was merely by 0.12 °C. On November 19, 2004, a wind-throw brushed the investigated area with an aftermath of 15.4% destroyed forest in the Bela basin, mainly along the area adjacent to the river. Therefore, in the second part of the study, the impact of the riparian vegetation growing along the river banks was evaluated for two distinctive periods, i.e. the period prior and after the wind-throw. We statistically analysed the changes in water temperature on 6-year time series of daily water temperature (November 2001 through November 2007). The results presented herein may be useful for defining boundary values for surface water temperature, as required by the EC Water Framework Directive.

Pekárová, Pavla; Miklánek, Pavol; Halmová, Dana; Onderka, Milan; Pekár, Ján; Ku?árová, Katarína; Liová, So?a; Škoda, Peter

2011-04-01

310

Decadal variability of the Tropical Atlantic Ocean Surface Temperature in shipboard measurements and in a Global Ocean-Atmosphere model  

NASA Technical Reports Server (NTRS)

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.

Mehta, Vikram M.; Delworth, Thomas

1995-01-01

311

Exact solutions of laminar-boundary-layer equations with constant property values for porous wall with variable temperature  

NASA Technical Reports Server (NTRS)

Exact solution of the laminar-boundary-layer equations for wedge-type flow with constant property values are presented for transpiration-cooled surfaces with variable wall temperatures. The difference between wall and stream temperature is assumed proportional to a power of the distance from the leading edge. Solutions are given for a Prandtl number of 0.7 and ranges of pressure-gradient, cooling-air-flow, and wall-temperature-gradient parameters. Boundary-layer profiles, dimensionless boundary-layer thicknesses, and convective heat-transfer coefficients are given in both tabular and graphical form. Corresponding results for constant wall temperature and for impermeable surfaces are included for comparison purposes.

Donoughe, Patrick L; Livingood, John N B

1955-01-01

312

Analysis of heat transfer in a porous cooled wall with variable pressure and temperature along the coolant exit boundary  

NASA Technical Reports Server (NTRS)

Fluid from a reservior at constant pressure and temperature is forced through a porous wall of uniform thickness. The boundary through which the fluid exits has specified variations in pressure and temperature along it in one direction so that the flow and heat transfer are two-dimensional. The local fluid and matrix temperatures are assumed to be equal and therefore a single energy equation governs the temperature distribution within the wall. The solution is obtained by transforming this energy equation into potential plane coordinates, which results in a separable equation. A technique yielding an integral equation is used to adapt the general solution so that it satisfies the variable-pressure boundary condition. Analytical expressions are given for the normal exit velocity and heat flux along the exit boundary. Illustrative examples are carried out which indicate to what extent the solution is locally one-dimensional.

Siegel, R.; Goldstein, M. E.

1972-01-01

313

A calorimeter for multilayer insulation (MLI) performance measurements at variable temperature  

NASA Astrophysics Data System (ADS)

Here we describe a concentric cylindrical calorimeter with radiation guards developed to measure the thermal performance of multilayer insulation (MLI) for low temperature applications. One unique feature of this calorimeter is its ability to independently control the boundary temperatures between room temperature and about 15 K using two single-stage Gifford-McMahon cryocoolers. Also, unlike the existing calorimeters that use the evaporation rate of a liquid cryogen to measure the heat load, in the present system the total heat transfer through the MLI is measured by recording the temperature difference across a calibrated heat load support rod that connects the cold inner cylinder to the lower temperature cryocooler. This design allows the continuous mapping of MLI performance over a much wider temperature range with independently controlled boundary conditions. The calorimeter is also suitable for performing a variety of radiation heat transfer experiments including the determination of the temperature dependence of the total emissivity.

Celik, D.; Hurd, J.; Klimas, R.; Van Sciver, S. W.

2013-05-01

314

Interannual Variability of Monsoon Precipitation and Local Subcloud Equivalent Potential Temperature  

E-print Network

to be caused by a contrast in the thermal forcing between land and ocean, and land surface thermal forcing of monsoon interannual variability are discussed. 1. Introduction Earth's seasonal cycle of insolation drives

315

The effect of subsurface temperature variability on the predictability of SST in the tropical Atlantic Ocean  

E-print Network

and Shukla, 1981; Hastenrath et al. , 1984; Lough, 1986; Enfield, 1996). Although El Nino-Southern Oscillation (ENSO) related SST variability in the tropical Pacific has a much wider impact on global climate than Atlantic SSTs and has been shown to affect..., 1990; Hastenrath and Greischar, 1993; Hastenrath and Druyan, 1993; Nobre and Shukla, 1996; Chang et aL, 1999). A recent study by Chiang and Kushnir (1999), correlates Northeast Brazil rainfall variability with Nino3 SST and the Atlantic inter...

Bates, Susan Carr

1999-01-01

316

Long-Term Extra-tropical Land Temperature Variability and Its Association with Solar and Volcanic Forcing  

NASA Astrophysics Data System (ADS)

It has long been hypothesized that a significant fraction of observed Northern Hemisphere (NH) temperature variability at multi-decadal to centennial time scales can be attributed to variations in solar activity. This argument has been supported by some modeling experiments that used long-term changes in solar irradiance, explosive volcanism, and anthropogenic trace gases to model temperature changes over the past 1,000 years. The modeled temperatures based on these radiative forcings often compare reasonably well to proxy-based NH temperature reconstructions covering the past 1,000 years, with solar forcing being important up to the mid-20th century, after which anthropogenic forcing dominates. Volcanic forcing is also important, but it operates in a more impulsive, episodic fashion. Consequently, its impact on proxy estimates of NH temperatures over the past 1,000 years may episodically distort and even overwhelm the effects of solar forcing on temperatures, thus breaking down what would otherwise be the appearance of a strong solar influence on past temperatures. While this problem can be investigated with models, the level of radiative forcing attributed to both solar and volcanic effects is still poorly constrained. Here, we statistically investigate the combined influences of solar and volcanic forcing in a land-only, extra-tropical NH temperature reconstruction. This record has been shown to have a strong statistical association with instrumental annual temperatures over the same region of the NH. Using estimates of solar irradiance and volcanic forcing, we show evidence for a centennial time-scale influence of solar forcing on past temperatures on the order of 700-1,000 years ago during a period of relatively high solar activity and little explosive volcanism. After that time, the frequency of explosive volcanism increases substantially, during a period of generally reduced solar activity, which appears to overwhelm solar forcing. In an effort to better reveal the underlying solar signal in the temperature reconstruction, we try to factor out the volcanic forcing signal, with limited success. It appears, therefore, that the emergence of solar forcing as a long-term agent of temperature change over extra-tropical NH land areas is highly dependent both on the magnitude of its forcing and on the frequency and timing of explosive volcanism as a competing agent of temperature variability and change.

Cook, E. R.

2004-12-01

317

Near-surface variability of temperature and salinity in the near-tropical ocean: Observations from profiling floats  

NASA Astrophysics Data System (ADS)

Upper ocean measurements of temperature and salinity obtained from profiling floats equipped with auxiliary surface temperature and salinity sensors (STS) are presented. Using these instruments, high vertical resolution (10 cm) measurements in the near-surface layer were acquired to within 20 cm of the sea surface, allowing for an examination of the ocean's near-surface structure and variability not usually possible. We examine the data from 62 Argo-type floats equipped with STS units deployed in the Pacific, Atlantic, and Indian Oceans. The vertical variability of temperature and salinity in the near-surface layer is characterized for each of these regions. While observations show the upper 4 m of the ocean are well mixed most of the time, this homogeneity is interrupted by significant and often short-lived warming/cooling and freshening events. In addition to the presence of barrier layers, a strong diurnal signal in temperature is observed, with salinity exhibiting somewhat weaker diurnal variations. The magnitude of the upper ocean diurnal cycle in temperature and salinity is largest in areas with light winds and heavy precipitation and was found to decay rapidly with depth (˜50% over the top 2 m). Storm events, validated from meteorological data collected from nearby TAO moorings and the Tropical Rainfall Measuring Mission (TRMM) satellite, show downward mixing of rainfall-derived freshwater to 10 m depth over only a few hours. Turner angle calculations show instability following these events.

Anderson, Jessica E.; Riser, Stephen C.

2014-11-01

318

A novel smart rotor support with shape memory alloy metal rubber for high temperatures and variable amplitude vibrations  

NASA Astrophysics Data System (ADS)

The work describes the design, manufacturing and testing of a smart rotor support with shape memory alloy metal rubber (SMA-MR) elements, able to provide variable stiffness and damping characteristics with temperature, motion amplitude and excitation frequency. Differences in damping behavior and nonlinear stiffness between SMA-MR and more traditional metal rubber supports are discussed. The mechanical performance shown by the prototype demonstrates the feasibility of using the SMA-MR concept for active vibration control in rotordynamics, in particular at high temperatures and large amplitude vibrations.

Ma, Yanhong; Zhang, Qicheng; Zhang, Dayi; Scarpa, Fabrizio; Liu, Baolong; Hong, Jie

2014-12-01

319

The role of surface vs. root-zone soil moisture variability for soil moisture-temperature coupling  

NASA Astrophysics Data System (ADS)

Hot extremes have been shown to be induced by antecedent surface moisture deficits in several regions. While most previous studies on this topic relied on modeling results or precipitation-based surface moisture information (particularly the standardized precipitation index, SPI), we use here a new merged remote sensing (RS) soil moisture product that combines active and passive microwave sensors to investigate the relation between the number of hot days (NHD) and preceding soil moisture deficits. Along with analyses of temporal variabilities of surface vs. root-zone soil moisture, this sheds light on the role of different soil depths for soil moisture-temperature coupling. The global patterns of soil moisture-NHD correlations from RS data and from SPI as used in previous studies are comparable. Nonetheless, the strength of the relationship appears underestimated with RS-based soil moisture compared to SPI-based estimates, particularly in regions of strong soil moisture-temperature coupling. This is mainly due to the fact that the temporal hydrological variability is less pronounced in the RS data than in the SPI estimates in these regions, and large dry/wet anomalies appear underestimated. Comparing temporal variabilities of surface and root-zone soil moisture in in-situ observations reveals a drop of surface-layer variability below that of root-zone when dry conditions are considered. This feature is a plausible explanation for the observed weaker relationship of RS-based soil moisture (representing the surface layer) with NHD as it leads to a gradual decoupling of the surface layer from temperature under dry conditions, while root-zone soil moisture sustains more of its temporal variability.

Hirschi, Martin; Mueller, Brigitte; Dorigo, Wouter; Seneviratne, Sonia I.

2014-05-01

320

Variable temperature infrared spectroscopy: A convenient tool for studying the thermodynamics of weak solid–gas interactions  

Microsoft Academic Search

This tutorial review describes the use of variable temperature infrared spectroscopy of adsorbed species (VTIR), a recent method for studying the thermodynamics of weak solid-gas interactions. Examples show how a fundamental relationship of thermodynamics (the van't Hoff equation, used long since in several fields of physical chemistry) can describe equilibrium processes at the solid-gas interface. The VTIR method is fully

Edoardo Garrone; Carlos Otero Arean

2005-01-01

321

Large Scale Variability of Phytoplankton Blooms in the Arctic and Peripheral Seas: Relationships with Sea Ice, Temperature, Clouds, and Wind  

NASA Technical Reports Server (NTRS)

Spatially detailed satellite data of mean color, sea ice concentration, surface temperature, clouds, and wind have been analyzed to quantify and study the large scale regional and temporal variability of phytoplankton blooms in the Arctic and peripheral seas from 1998 to 2002. In the Arctic basin, phytoplankton chlorophyll displays a large symmetry with the Eastern Arctic having about fivefold higher concentrations than those of the Western Arctic. Large monthly and yearly variability is also observed in the peripheral seas with the largest blooms occurring in the Bering Sea, Sea of Okhotsk, and the Barents Sea during spring. There is large interannual and seasonal variability in biomass with average chlorophyll concentrations in 2002 and 2001 being higher than earlier years in spring and summer. The seasonality in the latitudinal distribution of blooms is also very different such that the North Atlantic is usually most expansive in spring while the North Pacific is more extensive in autumn. Environmental factors that influence phytoplankton growth were examined, and results show relatively high negative correlation with sea ice retreat and strong positive correlation with temperature in early spring. Plankton growth, as indicated by biomass accumulation, in the Arctic and subarctic increases up to a threshold surface temperature of about 276-277 degree K (3-4 degree C) beyond which the concentrations start to decrease suggesting an optimal temperature or nutrient depletion. The correlation with clouds is significant in some areas but negligible in other areas, while the correlations with wind speed and its components are generally weak. The effects of clouds and winds are less predictable with weekly climatologies because of unknown effects of averaging variable and intermittent physical forcing (e.g. over storm event scales with mixing and upwelling of nutrients) and the time scales of acclimation by the phytoplankton.

Comiso, Josefino C.; Cota, Glenn F.

2004-01-01

322

Variability in stream discharge and temperatures during ecologically sensitive time periods: a preliminary assessment of the implications for Atlantic salmon  

NASA Astrophysics Data System (ADS)

This study focused on improving the understanding of the temporal variability in hydrological and thermal conditions and their potential influences on two life stages of Atlantic salmon (Salmo salar) - stream resident juveniles and returning adult spawners. Stream discharges and temperatures in the Girnock Burn, NE Scotland, a small nursery stream, were characterised over a time period of ten hydrological years (1994/95-2003/04). Frequency, magnitude, duration and timing of thermal, hydraulic and hydrological conditions were examined using data with a high temporal resolution (hourly and subhourly). Particular attention was focussed on assessing variations during ecologically sensitive time periods when salmon behaviour is most susceptible to environmental perturbations. The Girnock Burn was characterised by a strong inter- and intra-annual variability in the hydrological and thermal regime. This has clear implications for the likely feeding opportunities for juvenile fish in winter and early spring and the emergence of fry in the late spring. The movement of adult spawners towards breeding areas showed a complex dependence on hydrological variability. If discharges were low, fish movement was increasingly triggered by suboptimal flow increases as spawning time approached. Elucidating links between discharge/temperature variability and salmon habitat availability and utilization at appropriately fine temporal scales is a prerequisite to the development of better conservation management strategies and more biologically meaningful flow regimes in regulated river systems.

Tetzlaff, D.; Soulsby, C.; Youngson, A. F.; Gibbins, C.; Bacon, P. J.; Malcolm, I. A.; Langan, S.

2005-05-01

323

Temperature dependence of an estuarine harmful algal bloom: Resolving interannual variability in bloom dynamics using a degree day approach  

PubMed Central

Observations of harmful algal blooms (HABs) of the dinoflagellate Alexandrium fundyense in an estuary over multiple years were used to assess drivers of their spatial and temporal variability. Nauset Estuary on Cape Cod, Massachusetts has a recurrent, self-seeding A. fundyense population that produces paralytic shellfish poisoning toxins and leads to nearly annual closure to shellfishing. Weekly surveys of the entire estuary were made in 3 of 4 consecutive years, with surveys of a subembayment during the intervening year. Major A. fundyense blooms were observed all 4 years, with maximum concentrations >106 cells L?1. Concentrations were greatest in three salt ponds at the distal edges of the estuary. The bloom timing varied among the salt ponds and among years, although the blooms had similar durations and maximum cell concentrations. Nutrient concentrations did not correlate with the growth of the bloom, but differences in water temperature among years and ponds were significant. Net growth rates inferred from the surveys were similar to those from laboratory experiments, and increased linearly with temperature. A growing degree day calculation was used to account for effects of interannual variability and spatial gradients in water temperature on population development. The approach collapsed variability in the timing of bloom onset, development, and termination across years and among ponds, suggesting that this relatively simple metric could be used as an early-warning indicator for HABs in Nauset and similar areas with localized, self-seeding blooms. PMID:25419003

Ralston, David K.; Keafer, Bruce A.; Brosnahan, Michael L.; Anderson, Donald M.

2014-01-01

324

Interannual Variability of Temperature at a Depth of 125 Meters in the North Atlantic Ocean  

Microsoft Academic Search

Analyses of historical ocean temperature data at a depth of 125 meters in the North Atlantic Ocean indicate that from 1950 to 1990 the subtropical and subarctic gyres exhibited linear trends that were opposite in phase. In addition, multivariate analyses of yearly mean temperature anomaly fields between 20^circN and 70^circN in the North Atlantic show a characteristic space-time temperature oscillation

Sydney Levitus; John I. Antonov; Timothy P. Boyer

1994-01-01

325

The spatial variability of coastal surface water temperature during upwelling. [in Lake Superior  

NASA Technical Reports Server (NTRS)

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.

Scarpace, F. L.; Green, T., III

1979-01-01

326

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

USGS Publications Warehouse

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

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

2004-01-01

327

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

Microsoft Academic Search

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

Lingen Chen; Fankai Meng; Yanlin Ge; Fengrui Sun

2012-01-01

328

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

PubMed

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

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

2015-01-01

329

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

Microsoft Academic Search

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

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

2004-01-01

330

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

PubMed

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

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

2014-10-01

331

A new variable temperature solution-solid interface scanning tunneling microscope  

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

332

Temperature variability over the past millennium inferred from Northwestern Alaska tree rings  

Microsoft Academic Search

We describe a new tree-ring width data set of 14 white spruce chronologies for the Seward Peninsula (SP), Alaska, based on living and subfossil wood dating from 1358 to 2001 AD. A composite chronology derived from these data correlates positively and significantly with summer temperatures at Nome from 1910 to 1970, after which there is some loss of positive temperature

Rosanne D’Arrigo; Erika Mashig; David Frank; Rob Wilson; Gordon Jacoby

2005-01-01

333

Temporal Variability in Vertical Groundwater Fluxes and the Effect of Solar Radiation on Streambed Temperatures Based on Vertical High Resolution Distributed Temperature Sensing  

NASA Astrophysics Data System (ADS)

Due to its large spatial and temporal variability, groundwater discharge to streams is difficult to quantify. Methods using vertical streambed temperature profiles to estimate vertical fluxes are often of coarse vertical spatial resolution and neglect to account for the natural heterogeneity in thermal conductivity of streambed sediments. Here we report on a field investigation in a stream, where air, stream water and streambed sediment temperatures were measured by Distributed Temperature Sensing (DTS) with high spatial resolution to; (i) detect spatial and temporal variability in groundwater discharge based on vertical streambed temperature profiles, (ii) study the thermal regime of streambed sediments exposed to different solar radiation influence, (iii) describe the effect of solar radiation on the measured streambed temperatures. The study was carried out at a field site located along Holtum stream, in Western Denmark. The 3 m wide stream has a sandy streambed with a cobbled armour layer, a mean discharge of 200 l/s and a mean depth of 0.3 m. Streambed temperatures were measured with a high-resolution DTS system (HR-DTS). By helically wrapping the fiber optic cable around two PVC pipes of 0.05 m and 0.075 m outer diameter over 1.5 m length, temperature measurements were recorded with 5.7 mm and 3.8 mm vertical spacing, respectively. The HR-DTS systems were installed 0.7 m deep in the streambed sediments, crossing both the sediment-water and the water-air interface, thus yielding high resolution water and air temperature data as well. One of the HR-DTS systems was installed in the open stream channel with only topographical shading, while the other HR-DTS system was placed 7 m upstream, under the canopy of a tree, thus representing the shaded conditions with reduced influence of solar radiation. Temperature measurements were taken with 30 min intervals between 16 April and 25 June 2013. The thermal conductivity of streambed sediments was calibrated in a 1D flow and heat transport model (HydroGeoSphere). Subsequently, time series of vertical groundwater fluxes were computed based on the high-resolution vertical streambed sediment temperature profiles by coupling the model with PEST. The calculated vertical flux time series show spatial differences in discharge between the two HR-DTS sites. A similar temporal variability in vertical fluxes at the two test sites can also be observed, most likely linked to rainfall-runoff processes. The effect of solar radiation as streambed conduction is visible both at the exposed and shaded test site in form of increased diel temperature oscillations up to 14 cm depth from the streambed surface, with the test site exposed to solar radiation showing larger diel temperature oscillations.

Sebok, E.; Karan, S.; Engesgaard, P. K.; Duque, C.

2013-12-01

334

Synoptic drivers of 400 years of summer temperature and precipitation variability on Mt. Olympus, Greece  

NASA Astrophysics Data System (ADS)

The Mediterranean region has been identified as a global warming hotspot, where future climate impacts are expected to have significant consequences on societal and ecosystem well-being. To put ongoing trends of summer climate into the context of past natural variability, we reconstructed climate from maximum latewood density (MXD) measurements of Pinus heldreichii (1521-2010) and latewood width (LWW) of Pinus nigra (1617-2010) on Mt. Olympus, Greece. Previous research in the northeastern Mediterranean has primarily focused on inter-annual variability, omitting any low-frequency trends. The present study utilizes methods capable of retaining climatically driven long-term behavior of tree growth. The LWW chronology corresponds closely to early summer moisture variability (May-July, r = 0.65, p < 0.001, 1950-2010), whereas the MXD-chronology relates mainly to late summer warmth (July-September, r = 0.64, p < 0.001; 1899-2010). The chronologies show opposing patterns of decadal variability over the twentieth century (r = -0.68, p < 0.001) and confirm the importance of the summer North Atlantic Oscillation (sNAO) for summer climate in the northeastern Mediterranean, with positive sNAO phases inducing cold anomalies and enhanced cloudiness and precipitation. The combined reconstructions document the late twentieth—early twenty-first century warming and drying trend, but indicate generally drier early summer and cooler late summer conditions in the period ~1700-1900 CE. Our findings suggest a potential decoupling between twentieth century atmospheric circulation patterns and pre-industrial climate variability. Furthermore, the range of natural climate variability stretches beyond summer moisture availability observed in recent decades and thus lends credibility to the significant drying trends projected for this region in current Earth System Model simulations.

Klesse, Stefan; Ziehmer, Malin; Rousakis, Georgios; Trouet, Valerie; Frank, David

2014-09-01

335

Analytical and experimental spur gear tooth temperature as affected by operating variables  

NASA Technical Reports Server (NTRS)

A gear tooth temperature analysis was performed using a finite element method combined with a calculated heat input, calculated oil jet impingement depth, and estimated heat transfer coefficients. Experimental measurements of gear tooth average surface temperatures and instanteous surface temperatures were made with a fast response infrared radiometric microscope. Increased oil jet pressure had a significant effect on both average and peak surface temperatures at both high load and speeds. Increasing the speed at constant load and increasing the load at constant speed causes a significant rise in average and peak surface temperatures of gear teeth. The oil jet pressure required for adequate cooling at high speed and load conditions must be high enough to get full depth penetration of the teeth. Calculated and experimental results were in good agreement with high oil jet penetration but showed poor agreement with low oil jet penetration depth.

Townsend, D. P.; Akin, L. S.

1980-01-01

336

Title: Interannual variability in the temperature-responsiveness of CO2 flux from forest and peatland soils  

NASA Astrophysics Data System (ADS)

Northern forests and peatlands store large amounts of carbon in soils. The development of robust predictions of carbon fluxes from these ecosystems is important to improving biogeochemical models, especially in the context of global environmental change. We measured fluxes of CO2 from upland forest and peatland soils in the Marcell Experimental Forest (northern Minnesota, USA) from 2005 through 2007. We compared fluxes from upland and peatland hydrologic settings and also used regression approaches to examine the effectiveness of soil temperature, soil moisture, and water table level in predicting CO2 flux. Differences between upland and peatland CO2 flux were sometimes apparent but were not consistent across sampling years. In 2005, the mean upland CO2 flux was significantly higher than the mean peatland flux; in both 2006 and 2007, peatland fluxes exceeded upland fluxes, though the difference was not significant. Soil temperature was generally a stronger predictor of CO2 flux than was soil moisture or water table, but its predictive strength varied by hydrologic setting and year. In 2005, these variables explained roughly 60 percent of the variation of CO2 flux in both uplands and peatlands, but the strength of these predictive relationships declined in 2006 and 2007. Our study highlights the potential role of soil temperature in feedbacks between climate and the carbon cycle, but also illustrates a strong need for understanding interannual variability in the temperature responsiveness of CO2 flux.

Weishampel, P.; King, J. Y.; Kolka, R. K.

2008-12-01

337

Steady state temperature distribution in dermal regions of an irregular tapered shaped human limb with variable eccentricity.  

PubMed

The investigators in the past have developed some models of temperature distribution in the human limb assuming it as a regular circular or elliptical tapered cylinder. But in reality the limb is not of regular tapered cylindrical shape. The radius and eccentricity are not same throughout the limb. In view of above a model of temperature distribution in the irregular tapered elliptical shaped human limb is proposed for a three dimensional steady state case in this paper. The limb is assumed to be composed of multiple cylindrical substructures with variable radius and eccentricity. The mathematical model incorporates the effect of blood mass flow rate, metabolic activity and thermal conductivity. The outer surface is exposed to the environment and appropriate boundary conditions have been framed. The finite element method has been employed to obtain the solution. The temperature profiles have been computed in the dermal layers of a human limb and used to study the effect of shape, microstructure and biophysical parameters on temperature distribution in human limbs. The proposed model is one of the most realistic model as compared to conventional models as this can be effectively employed to every regular and nonregular structures of the body with variable radius and eccentricity to study the thermal behaviour. PMID:25086970

Agrawal, M; Pardasani, K R; Adlakha, N

2014-08-01

338

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

339

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

PubMed Central

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

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

2013-01-01

340

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

SciTech Connect

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

Fei, Yiyan; Landry, James P.; Zhu, X. D., E-mail: xdzhu@physics.ucdavis.edu [Department of Physics, University of California, One Shields Avenue, Davis, California 95616 (United States); Li, Yanhong; Yu, Hai; Lau, Kam; Huang, Shengshu; Chokhawala, Harshal A.; Chen, Xi [Department of Chemistry, University of California, One Shields Avenue, Davis, California 95616 (United States)] [Department of Chemistry, University of California, One Shields Avenue, Davis, California 95616 (United States)

2013-11-15

341

Relationships between Pacific and Atlantic ocean sea surface temperatures and U.S. streamflow variability  

E-print Network

influenced non-ENSO streamflow regions (Upper Colorado River basin and middle Atlantic United States). ENSO, while during the warm phase of the AMO, Atlantic Ocean SSTs influenced upper Mississippi River basin and continental U.S. precipitation (and drought) variability has been examined, water managers could ben- efit

Piechota, Thomas C.

342

Linking Global Climate and Temperature Variability to Widespread Amphibian Declines Putatively Caused by Disease  

Microsoft Academic Search

The role of global climate change in the decline of biodiversity and the emergence of infectious diseases remains controversial, and the effect of climatic variability, in particular, has largely been ignored. For instance, it was recently revealed that the proposed link between climate change and widespread amphibian declines, putatively caused by the chytrid fungus Batrachochytrium dendrobatidis (Bd), was tenuous because

Jason R. Rohr; Thomas R. Raffel

2010-01-01

343

Trends and variability of daily and extreme temperature and precipitation in the Caribbean region, 1961-2010  

NASA Astrophysics Data System (ADS)

A workshop was held at the University of the West Indies, Jamaica, in May 2012 to build capacity in climate data rescue and to enhance knowledge about climate change in the Caribbean region. Scientists brought their daily surface temperature and precipitation data for an assessment of quality and homogeneity and for the preparation of climate change indices helpful for studying climate change in their region. This study presents the trends in daily and extreme temperature and precipitation indices in the Caribbean region for records spanning the 1961-2010 and 1986-2010 intervals. Overall, the results show a warming of the surface air temperature at land stations. Region-wide, annual means of the daily minimum temperatures (+1.4°C) have increased more than the annual means of the daily maximum temperatures (+0.95°C) leading to significant decrease in the diurnal temperature range. The frequency of warm days and warm nights has increased by more than 15% while 7% fewer cool days and 10% fewer cool night were found over the 50-year interval. These frequency trends are further reflected in a rise of the annual extreme high and low temperatures by ~1°C. Changes in precipitation indices are less consistent and the trends are generally weak. Small positive trends were found in annual total precipitation, daily intensity, maximum number of consecutive dry days and heavy rainfall events particularly during the period 1986-2010. Finally, aside from the observed climate trends, correlations between these indices and the Atlantic Multidecadal Oscillation (AMO) annual index suggest a coupling between land temperature variability and, to a lesser extent, precipitation extremes on the one hand, and the AMO signal of the North Atlantic surface sea temperatures.

Stephenson, Tannecia; Vincent, Lucie; Allen, Theodore; Van Meerbeeck, Cedric; McLean, Natalie

2013-04-01

344

Trends and variability of daily and extreme temperature and precipitation in the Caribbean region, 1961-2010  

NASA Astrophysics Data System (ADS)

A workshop was held at the University of the West Indies, Jamaica, in May 2012 to build capacity in climate data rescue and to enhance knowledge about climate change in the Caribbean region. Scientists brought their daily surface temperature and precipitation data for an assessment of quality and homogeneity and for the preparation of climate change indices helpful for studying climate change in their region. This study presents the trends in daily and extreme temperature and precipitation indices in the Caribbean region for records spanning the 1961-2010 and 1986-2010 intervals. Overall, the results show a warming of the surface air temperature at land stations. Region-wide, annual means of the daily minimum temperatures (+1.4°C) have increased more than the annual means of the daily maximum temperatures (+0.9°C) leading to significant decrease in the diurnal temperature range. The frequency of warm days and warm nights has increased by more than 15% while 9% fewer cool days and 13% fewer cool night were found over the 50-year interval. These frequency trends are further reflected in a rise of the annual extreme high and low temperatures by ~1°C. Changes in precipitation indices are less consistent and the trends are generally weak. Small positive trends were found in annual total precipitation, daily intensity, maximum number of consecutive dry days and heavy rainfall events particularly during the period 1986- 2010. Finally, aside from the observed climate trends, correlations between these indices and the Atlantic Multidecadal Oscillation (AMO) annual index suggest a coupling between land temperature variability and, to a lesser extent, precipitation extremes on the one hand, and the AMO signal of the North Atlantic surface sea temperatures.

Allen, T. L.; Stephenson, T. S.; Vincent, L.; Van Meerbeeck, C.; McLean, N.

2013-05-01

345

Temperature effects on zoeal morphometric traits and intraspecific variability in the hairy crab Cancer setosus across latitude  

NASA Astrophysics Data System (ADS)

Phenotypic plasticity is an important but often ignored ability that enables organisms, within species-specific physiological limits, to respond to gradual or sudden extrinsic changes in their environment. In the marine realm, the early ontogeny of decapod crustaceans is among the best known examples to demonstrate a temperature-dependent phenotypic response. Here, we present morphometric results of larvae of the hairy crab Cancer setosus, the embryonic development of which took place at different temperatures at two different sites (Antofagasta, 23°45' S; Puerto Montt, 41°44' S) along the Chilean Coast. Zoea I larvae from Puerto Montt were significantly larger than those from Antofagasta, when considering embryonic development at the same temperature. Larvae from Puerto Montt reared at 12 and 16°C did not differ morphometrically, but sizes of larvae from Antofagasta kept at 16 and 20°C did, being larger at the colder temperature. Zoea II larvae reared in Antofagasta at three temperatures (16, 20, and 24°C) showed the same pattern, with larger larvae at colder temperatures. Furthermore, larvae reared at 24°C, showed deformations, suggesting that 24°C, which coincides with temperatures found during strong EL Niño events, is indicative of the upper larval thermal tolerance limit. C. setosus is exposed to a wide temperature range across its distribution range of about 40° of latitude. Phenotypic plasticity in larval offspring does furthermore enable this species to locally respond to the inter-decadal warming induced by El Niño. Morphological plasticity in this species does support previously reported energetic trade-offs with temperature throughout early ontogeny of this species, indicating that plasticity may be a key to a species’ success to occupy a wide distribution range and/or to thrive under highly variable habitat conditions.

Weiss, Monika; Thatje, Sven; Heilmayer, Olaf

2010-06-01

346

Variable temperature infrared spectroscopy: a convenient tool for studying the thermodynamics of weak solid-gas interactions.  

PubMed

This tutorial review describes the use of variable temperature infrared spectroscopy of adsorbed species (VTIR), a recent method for studying the thermodynamics of weak solid-gas interactions. Examples show how a fundamental relationship of thermodynamics (the van't Hoff equation, used long since in several fields of physical chemistry) can describe equilibrium processes at the solid-gas interface. The VTIR method is fully exploited by measuring absorbance of an IR band, temperature and pressure over a wide temperature range: an estimation of the interaction energy is, however, possible even ignoring the equilibrium pressure. Precise thermodynamic characterization of solid-gas interactions is required in several fields: on the applied side, gas sensing, separation and storage, which involve such areas as work-place security, air pollution control and the energy sector; regarding fundamental knowledge, weak solid-gas interactions are relevant to a number of fields, including hydrogen bonding, coordination chemistry and surface phenomena in a broad sense. Infrared (IR) spectroscopy of (gas) molecules adsorbed on a solid is frequently used to characterize both, the adsorbed species and the adsorbing centres at the solid surface. The potential of the technique can be greatly enhanced by obtaining IR spectra over a temperature range, and simultaneously measuring IR absorbance, temperature and equilibrium pressure. When this is done, variable temperature infrared (VTIR) spectroscopy can be used not only for a more detailed surface characterization, but also for precise studies on the thermodynamics of solid-gas interactions. Furthermore, when weak interactions are concerned, the technique shows favourable features compared to adsorption calorimetry, or to other classical methods. The potential of the VTIR method is highlighted by reviewing recently reported studies on dihydrogen, dinitrogen and carbon monoxide adsorption on zeolites. To facilitate understanding, an outline of the basis of the method is also given, together with an appraisal of the critical points involved in its practical use. PMID:16172674

Garrone, Edoardo; Otero Areán, Carlos

2005-10-01

347

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

PubMed

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

Studer, A; Poulin, R

2014-05-01

348

A new variable for maximizing the superconductive transition temperature in oxide systems  

NASA Astrophysics Data System (ADS)

The maximum transition temperature in superconductive oxides appears to occur when the oxygen sublattice is completely filled. Variation of the conditions of preparation may open an additional path to establish this condition.

Kroger, F. A.

1991-06-01

349

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

SciTech Connect

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

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

1986-11-01

350

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

EPA Science Inventory

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

351

Evidence for Solar Forcing in Variability of Temperatures and Pressures in Europe  

NASA Astrophysics Data System (ADS)

We have analyzed daily minimum and mean temperatures and pressures from respectively 48 and 23 meteorological stations from Europe over the 20th century. We will briefly discuss correlations between individual time series and describe the overall averages. Both series display a dominant, stochastic spectral content in the 3-15yr period range. The temperature series displays a sharp minimum near 1940, possibly related to an unusual El Niño event, and a step-like jump of about 1°C near 1987, whose origin is as yet unknown. The longer- term trend is flat both before and after the 1987 jump, so that global warming in Europe amounts to this step-like change in 1987. We next study the temporal evolution of disturbances of these European temperature and pressure series, as measured by evaluating the "lifetime" of these data, using a novel nonlinear filtering technique. Both temperature and pressure lifetimes are remarkably well correlated at all scales. Temperature lifetimes display sharp primary and lesser secondary maxima at the times of extrema in sunspot number, with a phase shift around 1960. Disturbances of both temperature and pressure series are dominated by wintertime perturbations. The solar signature in the wintertime disturbances is especially strong throughout the 20-th century. Long-term changes of disturbances of temperature and pressure display remarkable similarity over the entire 20th century, rising from 1900 to 1950, decreasing from 1950 to 1970, rising since 1970, sometimes with a plateau after 1980. We recognize in all these series the signature of long-term solar evolution. Although the worldwide character of these observations remains to be studied, these strong correlations emphasise the role of the Sun as a significant forcing factor of atmospheric temperature and pressure.

Courtillot, V.; Le Mouël, J.; Blanter, E.; Shnirman, M.

2008-05-01

352

Little Ice Age sea surface temperature variability in the southwest tropical Pacific  

Microsoft Academic Search

We present a 60-year near-monthly record of tropical sea surface temperature (SST) during the Little Ice Age derived from coupled Sr\\/Ca and U\\/Ca analysis of a massive coral from New Caledonia (southwest tropical Pacific). The record indicates that, from 1701 to 1761, surface temperatures were on average 1.4°C cooler than during the past 30 years. This cooling was accompanied by

Thierry Corrège; Terry Quinn; Thierry Delcroix; Florence Le Cornec; Jacques Récy; Guy Cabioch

2001-01-01

353

Climatic change by cloudiness linked to the spatial variability of sea surface temperatures  

NASA Technical Reports Server (NTRS)

An active role in modifying the earth's climate is suggested for low cloudiness over the circumarctic oceans. Such cloudiness, linked to the spatial differences in ocean surface temperatures, was studied. The temporal variations from year to year of ocean temperature patterns can be pronounced and therefore, the low cloudiness over this region should also show strong temporal variations, affecting the albedo of the earth and therefore the climate. Photographs are included.

Otterman, J.

1975-01-01

354

Modelling temporal and large-scale spatial variability of soil respiration from soil water availability, temperature and vegetation productivity indices  

NASA Astrophysics Data System (ADS)

Field-chamber measurements of soil respiration from 17 different forest and shrubland sites in Europe and North America were summarized and analyzed with the goal to develop a model describing seasonal, inter-annual and spatial variability of soil respiration as affected by water availability, temperature and site properties. The analysis was performed at a daily and at a monthly time step. With the daily time step, the relative soil water content in the upper soil layer expressed as a fraction of field capacity was a good predictor of soil respiration at all sites. Among the site variables tested, those related to site productivity (e.g. leaf area index) correlated significantly with soil respiration, while carbon pool variables like standing biomass or the litter and soil carbon stocks did not show a clear relationship with soil respiration. Furthermore, it was evidenced that the effect of precipitation on soil respiration stretched beyond its direct effect via soil moisture. A general statistical non-linear regression model was developed to describe soil respiration as dependent on soil temperature, soil water content and site-specific maximum leaf area index. The model explained nearly two thirds of the temporal and inter-site variability of soil respiration with a mean absolute error of 0.82 µmol m-2 s-1. The parameterised model exhibits the following principal properties: 1) At a relative amount of upper-layer soil water of 16% of field capacity half-maximal soil respiration rates are reached. 2) The apparent temperature sensitivity of soil respiration measured as Q10 varies between 1 and 5 depending on soil temperature and water content. 3) Soil respiration under reference moisture and temperature conditions is linearly related to maximum site leaf area index. At a monthly time-scale we employed the approach by Raich et al. (2002, Global Change Biol. 8, 800-812) that used monthly precipitation and air temperature to globally predict soil respiration (T&P-model). While this model was able to explain some of the month-to-month variability of soil respiration, it failed to capture the inter-site variability, regardless whether the original or a new optimized model parameterization was used. In both cases, the residuals were strongly related to maximum site leaf area index. Thus, for a monthly time scale we developed a simple T&P&LAI-model that includes leaf area index as an additional predictor of soil respiration. This extended but still simple model performed nearly as well as the more detailed time-step model and explained 50 % of the overall and 65% of the site-to-site variability. Consequently, better estimates of globally distributed soil respiration should be obtained with the new model driven by satellite estimates of leaf area index.

Reichstein, M.; Rey, A.; Freibauer, A.; Tenhunen, J.; Valentini, R.; Soil Respiration Synthesis Team

2003-04-01

355

Modeling temporal and large-scale spatial variability of soil respiration from soil water availability, temperature and vegetation productivity indices  

NASA Astrophysics Data System (ADS)

Field-chamber measurements of soil respiration from 17 different forest and shrubland sites in Europe and North America were summarized and analyzed with the goal to develop a model describing seasonal, interannual and spatial variability of soil respiration as affected by water availability, temperature, and site properties. The analysis was performed at a daily and at a monthly time step. With the daily time step, the relative soil water content in the upper soil layer expressed as a fraction of field capacity was a good predictor of soil respiration at all sites. Among the site variables tested, those related to site productivity (e.g., leaf area index) correlated significantly with soil respiration, while carbon pool variables like standing biomass or the litter and soil carbon stocks did not show a clear relationship with soil respiration. Furthermore, it was evidenced that the effect of precipitation on soil respiration stretched beyond its direct effect via soil moisture. A general statistical nonlinear regression model was developed to describe soil respiration as dependent on soil temperature, soil water content, and site-specific maximum leaf area index. The model explained nearly two thirds of the temporal and intersite variability of soil respiration with a mean absolute error of 0.82 ?mol m-2 s-1. The parameterized model exhibits the following principal properties: (1) At a relative amount of upper-layer soil water of 16% of field capacity, half-maximal soil respiration rates are reached. (2) The apparent temperature sensitivity of soil respiration measured as Q10 varies between 1 and 5 depending on soil temperature and water content. (3) Soil respiration under reference moisture and temperature conditions is linearly related to maximum site leaf area index. At a monthly timescale, we employed the approach by [2002] that used monthly precipitation and air temperature to globally predict soil respiration (T&P model). While this model was able to explain some of the month-to-month variability of soil respiration, it failed to capture the intersite variability, regardless of whether the original or a new optimized model parameterization was used. In both cases, the residuals were strongly related to maximum site leaf area index. Thus, for a monthly timescale, we developed a simple T&P&LAI model that includes leaf area index as an additional predictor of soil respiration. This extended but still simple model performed nearly as well as the more detailed time step model and explained 50% of the overall and 65% of the site-to-site variability. Consequently, better estimates of globally distributed soil respiration should be obtained with the new model driven by satellite estimates of leaf area index. Before application at the continental or global scale, this approach should be further tested in boreal, cold-temperate, and tropical biomes as well as for non-woody vegetation.

Reichstein, Markus; Rey, Ana; Freibauer, Annette; Tenhunen, John; Valentini, Riccardo; Banza, Joao; Casals, Pere; Cheng, Yufu; Grünzweig, Jose M.; Irvine, James; Joffre, Richard; Law, Beverly E.; Loustau, Denis; Miglietta, Franco; Oechel, Walter; Ourcival, Jean-Marc; Pereira, Joao S.; Peressotti, Alessandro; Ponti, Francesca; Qi, Ye; Rambal, Serge; Rayment, Mark; Romanya, Joan; Rossi, Federica; Tedeschi, Vanessa; Tirone, Giampiero; Xu, Ming; Yakir, Dan

2003-12-01

356

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

E-print Network

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

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

2008-08-05

357

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

Microsoft Academic Search

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

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

2008-01-01

358

Effect of design variables, temperature gradients and speed of life and reliability of a rotating disk  

NASA Technical Reports Server (NTRS)

A generalized methodology to predict the fatigue life and reliability of a rotating disk such as used for aircraft engine turbines and compressors is advanced. The approach incorporates the computed life of elemental stress volumes to predict system life and reliability. Disk speed and thermal gradients as well as design variables such as disk diameter and thickness and bolt hole size, number and location are considered.

Zaretsky, E. V.; Smith, T. E.; August, R.

1986-01-01

359

Comparisons of two methods of removing anthropogenically related variability from the near-surface observational temperature field  

NASA Astrophysics Data System (ADS)

Assessments of the veracity of model-generated variability are difficult because variability in observed climate data during the 20th century is composed of natural and anthropogenic (greenhouse gas and sulfate aerosol) factors in addition to internal climate fluctuations. Comparisons should be improved if some of these factors could either be extracted from real world data or additions be made to model-generated variability. Both options involve several assumptions, the most important of which is that the climate system is linear to a first approximation. We discuss this and other assumptions and present results from two different methods of removing variability related to anthropogenic factors using energy balance models (EBMs) and atmosphere/ocean general circulation models (A/OGCMs). At a global scale, the pattern of the trend of surface temperature over the 1966-1995 period, after removing the anthropogenic effect, shows some strong similarities between the two methods, with the strongest residual warming evident over much of northern Asia and northern North America.

Jones, P. D.; Hegerl, G. C.

1998-06-01

360

Latitude and Altitude Dependence of the Interannual Variability and Trends of Atmospheric Temperatures  

NASA Astrophysics Data System (ADS)

The 4-season (12-month) running means of temperatures at five atmospheric levels (surface, 850-300 mb, 300-100 mb, 100-50 mb, 100-30 mb) and seven climatic zones (60°N-90°N, 30°N-60°N, 10°N-30°N, 10°N-10°S, 10°S-30°S, 30°S-60°S, 60°S-90°S) showed QBO (Quasi-biennial Oscillation), QTO (Quasi-triennial Oscillation) and larger periodicities. For stratosphere and tropopause, the temperature variations near the equator and North Pole somewhat resembled the 50mb low latitude zonal winds, mainly due to prominent QBO. For troposphere and surface, the temperature variations, especially those near the equator, resemble those of eastern equatorial Pacific sea-surface temperatures, mainly due to prominent QTO. In general, the temperature trends in the last 35 years show stratospheric cooling and tropospheric warming. But the trends are not monotonic. For example, the surface trends were downward during 1960-70, upward during 1970-82, downward during 1982-85 and upward thereafter. Models of green-house warming should take these non-uniformities into account.

Kane, R. P.; Buriti, R. A.

1997-08-01

361

Changes in inter-annual variability of precipitation and temperature over Mexico and Central America from RegCM projections  

NASA Astrophysics Data System (ADS)

Future climate projections performed with the Regional Climate Model (RegCM4) are used to analyze the future changes on inter-annual variability of precipitation and temperature over Mexico and Central America. Two different global circulation models from the Couple Model Intercomparison Project phase 5 (CMPI5) are used as boundary conditions for two different RegCM4 configurations, which result in four different climate projections. Through a comparison of the precipitation annual cycles in reference period with future simulations, a shift in the annual cycle is found over Northwestern Mexico and Central America. During the rainy season (June to September), it is found an increase in the inter-annual variability of precipitation and temperature, together with a warming greater than 4°C in the mean seasonal temperature and a drying of more than 20%. An increased warming on the Eastern Pacific Ocean compared to the Tropical North Atlantic Ocean potentially generates a strengthened North Atlantic Subtropical High Pressure and also a stronger Caribbean Low Level Jet. This future ENSO-like state appears to be the mechanism driving the drying over the region

Fuentes-Franco, Ramon; Coppola, Erika; Tefera Diro, Gulilat; Giorgi, Filippo; Pavia, Edgar G.; Graef, Federico

2013-04-01

362

Using high-resolution distributed temperature sensing to quantify spatial and temporal variability in vertical hyporheic flux  

NASA Astrophysics Data System (ADS)

Hyporheic flow can be extremely variable in space and time, and our understanding of complicated flow systems, such as exchange around small dams, has generally been limited to reach-averaged parameters or discrete point measurements. Emerging techniques are starting to fill the void between these disparate scales, increasing the utility of hyporheic research. When ambient diurnal temperature patterns are collected at high spatial resolution across vertical profiles in the streambed, the data can be applied to one-dimensional conduction-advection-dispersion models to quantitatively describe the vertical component of hyporheic flux at the same high spatial resolution. We have built on recent work by constructing custom fiber-optic distributed temperature sensors with 0.014 m spatial resolution that are robust enough to be installed by hand into the streambed, maintain high signal strength, and permit several sensors to be run in series off a single distributed temperature sensing unit. Data were collected continuously for 1 month above two beaver dams in a Wyoming stream to determine the spatial and temporal nature of vertical flux induced by the dams. Flux was organized by streambed morphology with strong, variable gradients with depth indicating a transition to horizontal flow across a spectrum of hyporheic flow paths. Several profiles showed contrasting temporal trends as discharge decreased by 45%. The high-resolution thermal sensors, combined with powerful analytical techniques, allowed a distributed quantitative description of the morphology-driven hyporheic system not previously possible.

Briggs, Martin A.; Lautz, Laura K.; McKenzie, Jeffrey M.; Gordon, Ryan P.; Hare, Danielle K.

2012-02-01

363

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

SciTech Connect

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

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

2001-01-01

364

Relationship between historical sea-surface temperature variability and climate change-induced coral mortality in the western Indian Ocean.  

PubMed

Many of the world's coral reefs suffered high coral mortality during the 1998 ENSO, with the highest mortality in the western Indian Ocean (WIO). A meta-analysis of field data on change in coral cover across the 1998 ENSO event was conducted for 36 major reef areas in the WIO, and relationship of the change with the historical sea-surface temperature (SST) variability investigated. WIO reefs were categorized into three major SST groups of differing coral cover change. Cover change was negatively associated with standard deviation (SD) SST until about SD 2.3, with increasing flatness of the SST frequency distributions. It increased with further increase in SD as the SST distributions became strongly bimodal in the Arabian/Persian Gulf area. The study indicates that environmental resistance/tolerance to extreme anomalous events could be predicted and management priorities directed accordingly for a warmer and more variable future climate. PMID:20447661

Ateweberhan, M; McClanahan, Tim R

2010-07-01

365

Temperature-dependent daily variability of precipitable water in special sensor microwave/imager observations  

NASA Technical Reports Server (NTRS)

We use retrievals of atmospheric precipitable water from satellite microwave observations and analyses of near-surface temperature to examine the relationship between these two fields on daily and longer time scales. The retrieval technique producing the data used here is most effective over the open ocean, so the analysis focuses on the southern hemisphere's extratropics, which have an extensive ocean surface. For both the total and the eddy precipitable water fields, there is a close correspondence between local variations in the precipitable water and near-surface temperature. The correspondence appears particularly strong for synoptic and planetary scale transient eddies. More specifically, the results support a typical modeling assumption that transient eddy moisture fields are proportional to transient eddy temperature fields under the assumption f constant relative humidity.

Gutowski, William J.; Lindemulder, Elizabeth A.; Jovaag, Kari

1995-01-01

366

Transport critical current measurement apparatus using liquid nitrogen cooled high-Tc superconducting magnet with variable temperature insert  

NASA Astrophysics Data System (ADS)

We have developed an apparatus to investigate transport critical current (Ic) as a function of magnetic field and temperature using only liquid nitrogen. The apparatus consists of a (Bi,Pb)2Sr2Ca2Cu3O10 (Bi-2223) superconducting magnet, an outer dewar, and a variable temperature insert (VTI). The magnet, which is operated in depressurized liquid nitrogen, generates magnetic field up to 1.26 T. The sample is also immersed in liquid nitrogen. The pressure in the VTI is controlled from 0.02 to 0.3 MPa, which corresponds to temperature ranging from 66 to 88 K. We have confirmed the long-term stable operation of the Bi-2223 magnet at 1 T. The temperature stability of the sample at high transport current was also demonstrated. The apparatus provides easy-operating Ic measurement environment for a high-Tc superconductor up to 500 A in magnetic fields up to 1 T and in temperatures ranging from 66 to 88 K.

Nishijima, G.; Kitaguchi, H.; Tshuchiya, Y.; Nishimura, T.; Kato, T.

2013-01-01

367

Influence of variable temperatures irradiation on microstructural evolution in phosphorus doped Fe–Cr–Ni alloys  

Microsoft Academic Search

To evaluate the influence of temperature change on microstructural evolution in phosphorus modified Fe–Cr–Ni alloys, irradiations at 473\\/923, 673\\/923, 773\\/923 K were performed on a Fe–16Cr–17Ni–0.1P alloy with 2.4 MeV Cu ions. In these experiments, specimen temperature was changed in a stepwise manner during the irradiation. In the case of 673\\/923 K-irradiation, the phosphide density after the second irradiation at

D. Hamaguchi; H. Watanabe; T. Muroga; N. Yoshida

2000-01-01

368

Single-crystal variable temperature EPR study of Cr 3+ in zinc maleate tetrahydrate  

NASA Astrophysics Data System (ADS)

X-band (9.60 GHz) EPR measurements were carried out on a single-crystal of Cr 3+-doped zinc maleate tetrahydrate at room, liquid-nitrogen, and liquid helium temperatures for various orientations of the external magnetic field in three mutually perpendicular planes. The values of the spin-Hamiltonian parameters were estimated using a rigorous least-squares fitting procedure. The absolute sign of the zero-field splitting parameter, b02, was determined to be negative from liquid-helium temperature data, and its value was found to be unusually large (?15 GHz).

Misra, Sushil K.; Isber, Samih; Chand, Prem

2000-08-01

369

Spatial Variability of Nutrient Concentrations and Stream Temperatures within the McKenzie River Basin: Abiotic and Biotic Controls  

NASA Astrophysics Data System (ADS)

Ecosystem controls of nutrient dynamics and of stream temperature are complex, especially as we scale from headwaters to larger systems. Water temperature is influenced by biotic, climatic, hydrologic and geomorphic factors, yet the interactions of these factors contributing to spatial variation in temperature is not well understood. Similarly, how well can we predict nutrient dynamics with increasing drainage area of streams? Can nutrient concentrations be interpolated or extrapolated from known points within the stream network? Independent measures of stream temperature and stream nutrient concentrations within the McKenzie River Basin reveal the influences of flow path and hydraulic retention times as dominant factors for stream temperature and phosphorous. Stream flows originating from subsurface aquifers have distinct phosphorous and temperature signals compared to those from near surface sources. In this region, P concentrations are highly influenced by volcanic bedrock and streams with the highest P also have cold summer temperatures, suggesting that their source of water is deep aquifers, with long residence times of water. Geomorphic controls (substrate type, hyporheic flow and groundwater inputs) can have as large an impact on diurnal stream temperature dynamics as the removal of riparian vegetation. Conversely, nitrogen dynamics and dominance of DON versus DIN are less predictable. Previous experiments showed rapid transformation of ammonia to nitrate, leading to a hypothesis of increased nitrate concentrations with distance downstream at low flow. However, synoptic nutrient sampling from first- through eighth- order streams and rivers found the highest nitrate concentrations and greatest variability among first- and second-order streams. Larger streams within the H.J. Andrews Experimental Forest and downstream to the confluence of the McKenzie River with the Willamette showed less variability. Surprisingly, downstream sites had lower nitrate concentrations than upstream, even with point and non-point anthropogenic inputs. These results confirm that abiotic processes are controlling availability of P in streams, while species of N are more tightly coupled to biotic mechanisms and transformations. Synoptic nutrient sampling along the longitudinal gradient of rivers coupled with mechanistic studies at headwater sites will increase our understanding of biotic and abiotic interactions which influence nutrient retention and release from basins.

Johnson, S. L.

2001-12-01

370

Variability in stream discharge and temperature: a preliminary assessment of the implications for juvenile and spawning Atlantic salmon  

NASA Astrophysics Data System (ADS)

This study focuses on understanding the temporal variability in hydrological and thermal conditions in a small mountain stream and its potential implication for two life stages of Atlantic salmon (Salmo salar) - stream resident juveniles and returning adult spawners. Stream discharge and temperature in the Girnock Burn, NE Scotland, were characterised over ten hydrological years (1994/1995-2003/2004). Attention was focussed on assessing variations during particular ecologically "sensitive" time periods when selected life-stages of salmon behaviour may be especially influenced by hydrological and thermal conditions. Empirical discharge data were used to derive hydraulic parameters to predict the Critical Displacement Velocity (CDV) of juvenile salmon. This is the velocity above which fish may no longer be able to hold station in the water column and thus can be used as an index of time periods where feeding behaviour might be constrained. In the Girnock Burn, strong inter- and intra-annual variability in hydrological and thermal conditions may have important implications for feeding opportunities for juvenile fish; both during important growth periods in late winter and early spring, and the emergence of fry in the late spring. Time periods when foraging behaviour of juvenile salmon may be constrained by hydraulic conditions were assessed as the percentage time when CDV for 0+ and 1+ fish were exceeded by mean daily stream velocities. Clear seasonal patterns of CDV were apparent, with higher summer values driven by higher stream temperatures and fish length. Inter-annual variability in the time when mean stream velocity exceeded CDV for 0+ fish ranged between 29.3% (1997/1998) and 44.7% (2000/2001). For 1+ fish mean stream velocity exceeded CDV between 14.5% (1997/1998) and 30.7% (2000/2001) of the time. The movement of adult spawners into the Girnock Burn in preparation for autumn spawning (late October to mid-November) exhibited a complex relationship with hydrological variability with marked inter-annual contrasts. In years when discharge in the period prior to spawning was low, fish movement was increasingly triggered by suboptimal flow increases as spawning time approached. In contrast, wet years with numerous events allowed a much more even distribution of fish entry. Elucidating links between discharge/temperature variability and foraging opportunities and upriver migration of adult Atlantic salmon have the potential to contribute to the improvement of conservation strategies in both regulated and unregulated rivers.

Tetzlaff, D.; Soulsby, C.; Youngson, A. F.; Gibbins, C.; Bacon, P. J.; Malcolm, I. A.; Langan, S.

2005-09-01

371

Large Temperature Variability in a Southern Tropical Continental Setting Through the Last Glacial Maximum  

Microsoft Academic Search

The magnitude and timing of temperature change since the Last Glacial Maximum (LGM) on the tropical continents is becoming better understood as the box of independent paleotemperature tools for continental systems expands. Here we present a paleotemperature record derived from the application of TEX86 to lacustrine sediments for Lake Malawi, East Africa through the LGM. We find a ˜4 °

L. A. Powers; T. C. Johnson; J. P. Werne; I. S. Castaneda; E. C. Hopmans; J. S. Damst; S. Schouten

2004-01-01

372

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

373

Temperature-dependent daily variability of precipitable water in special sensor microwave\\/imager observations  

Microsoft Academic Search

We use retrievals of atmospheric precipitable water from satellite microwave observations and analyses of near-surface temperature to examine the relationship between these two fields on daily and longer timescales. The retrieval technique producing the data used here is most effective over the open ocean, so the analysis focuses on the southern hemisphere's extratropics, which have an extensive ocean surface. For

William J. Gutowski; Elizabeth A. Lindemulder; Kari Jovaag

1995-01-01

374

Variable temperature spectroscopy of as-grown and passivated CdS nanowire optical waveguide cavities.  

PubMed

Semiconductor nanowire waveguide cavities hold promise for nanophotonic applications such as lasers, waveguides, switches, and sensors due to the tight optical confinement in these structures. However, to realize their full potential, high quality nanowires, whose emission at low temperatures is dominated by free exciton emission, need to be synthesized. In addition, a proper understanding of their complex optical properties, including light-matter coupling in these subwavelength structures, is required. We have synthesized very high-quality wurztite CdS nanowires capped with a 5 nm SiO(2) conformal coating with diameters spanning 100-300 nm using physical vapor and atomic layer deposition techniques and characterized their spatially resolved photoluminescence over the 77-298 K temperature range. In addition to the Fabry-Pe?rot resonator modulated emission from the ends of the wires, the low temperature emission from the center of the wire shows clear free excitonic peaks and LO phonon replicas, persisting up to room-temperature in the passivated wires. From laser scanning measurements we determined the absorption in the vicinity of the excitonic resonances. In addition to demonstrating the high optical quality of the nanowire crystals, these results provide the fundamental parameters for strong light-matter coupling studies, potentially leading to low threshold polariton lasers, sensitive sensors and optical switches at the nanoscale. PMID:21214218

van Vugt, Lambert K; Piccione, Brian; Cho, Chang-Hee; Aspetti, Carlos; Wirshba, Aaron D; Agarwal, Ritesh

2011-04-28

375

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

E-print Network

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

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

2003-01-01

376

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

PubMed Central

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

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

2012-01-01

377

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

PubMed

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

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

2012-10-01

378

Multiscale Variabilities in Global Sea Surface Temperatures and Their Relationships with Tropospheric Climate Patterns  

Microsoft Academic Search

El Nino-Southern Oscillation (ENSO) is a global phenomenon with significant phase propagation within and between basins. This is captured and described in the first mode of a complex empirical orthogonal function (CEOF) analysis of sea surface temperature anomaly (SSTA) from the midnineteenth century through 1991. The global ENSO from the SSTA data, plus a linear trend everywhere, are subsequently removed

David B. Enfield; Alberto M. Mestas-Nuñez

1999-01-01

379

Decadal Variability and Temperature Trends in the Middle Atmosphere From Historical Rocketsonde Data  

NASA Technical Reports Server (NTRS)

Observational studies were performed using historical rocketsonde data to investigate long-term temperature trends, solar-cycle variations, and interactions between tropical and extratropical latitudes in the middle atmosphere. Evidence from tropical, subtropical, and midlatitude North American rocketsonde stations indicated a consistent downward trend over 25 years, with a solar cycle component superposed. The trend is about -1.4 to -2.0 K per decade and the amplitude of the decadal oscillation is about 1.1 K. Prior to trend derivation it was necessary for us to correct temperatures for aerodynamic heating in the early years. The empirically derived correction profile agrees well with a theoretical profile of Krumins and Lyons. A study was also performed of the correlation between equatorial winds and north polar temperatures in winter, showing that the entire stratospheric wind profile near the equator -- including the quasi-biennial oscillation (QBO) and stratopause semiannual oscillation (SAO) -- is important to the extratropical flow, not merely the QBO component as previously thought. A strong correlation was discovered between winter polar temperatures and equatorial winds in the upper stratosphere during the preceding September, suggesting a role for the second cycle of the SAO.

Dunkerton, Timothy J.

2000-01-01

380

A CLIMATOLOGY OF TEMPERATURE AND PRECIPITATION VARIABILITY IN THE UNITED STATES  

EPA Science Inventory

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

381

Late Holocene variability of upper North Atlantic Deep Water temperature and salinity  

Microsoft Academic Search

Magnesium\\/calcium ratios in benthic foraminifera (Cibicidoides pachyderma) from a sediment core on the Laurentian Slope (1854 m) exhibit strong millennial-scale fluctuations during the past 4000 years. We convert these data to seawater paleotemperatures using a new monospecific linear equation. Results suggest that the temperature of upper North Atlantic Deep Water (dominated by Labrador Seawater today) has varied by at least

Thomas M. Marchitto; Peter B. deMenocal

2003-01-01

382

Late Holocene variability of upper North Atlantic Deep Water temperature and salinity  

Microsoft Academic Search

(1) Magnesium\\/calcium ratios in benthic foraminifera (Cibicidoides pachyderma) from a sediment core on the Laurentian Slope (1854 m) exhibit strong millennial-scale fluctuations during the past 4000 years. We convert these data to seawater paleotemperatures using a new monospecific linear equation. Results suggest that the temperature of upper North Atlantic Deep Water (dominated by Labrador Seawater today) has varied by at

Thomas M. Marchitto

2003-01-01

383

A YBCO RF-squid variable temperature susceptometer and its applications  

NASA Technical Reports Server (NTRS)

The Superconducting QUantum Interference Device (SQUID) susceptibility using a high-temperature radio-frequency (rf) SQUID and a normal metal pick-up coil is employed in testing weak magnetization of the sample. The magnetic moment resolution of the device is 1 x 10(exp -6) emu, and that of the susceptibility is 5 x 10(exp -6) emu/cu cm.

Zhou, Luwei; Qiu, Jinwu; Zhang, Xianfeng; Tang, Zhimin; Cai, Yimin; Qian, Yongjia

1991-01-01

384

Multidecadal North Atlantic sea surface temperature and Atlantic meridional overturning circulation variability in CMIP5 historical  

E-print Network

Multidecadal North Atlantic sea surface temperature and Atlantic meridional overturning circulation and interact with each other. Citation: Zhang, L., and C. Wang (2013), Multidecadal North Atlantic sea surface flowing colder water at depth. This circulation transports heat from the South Atlantic and tropical North

385

Studies of hot photoluminescence in plasmonically coupled silicon via variable energy excitation and temperature-dependent spectroscopy.  

PubMed

By integrating silicon nanowires (?150 nm diameter, 20 ?m length) with an ?-shaped plasmonic nanocavity, we are able to generate broadband visible luminescence, which is induced by high order hybrid nanocavity-surface plasmon modes. The nature of this super bandgap emission is explored via photoluminescence spectroscopy studies performed with variable laser excitation energies (1.959 to 2.708 eV) and finite difference time domain simulations. Furthermore, temperature-dependent photoluminescence spectroscopy shows that the observed emission corresponds to radiative recombination of unthermalized (hot) carriers as opposed to a resonant Raman process. PMID:25120156

Aspetti, Carlos O; Cho, Chang-Hee; Agarwal, Rahul; Agarwal, Ritesh

2014-09-10

386

Unprecedented recent warming rate and temperature variability over the east Tibetan Plateau inferred from Alpine treeline dendrochronology  

NASA Astrophysics Data System (ADS)

Despite instrumental records showing recent large temperature rises on the Tibetan Plateau (TP), only a few tree-ring temperature reconstructions do capture this warming trend. Here, we sampled 260 trees from seven Alpine treeline locations across the southeast TP. Standardized tree-ring width chronologies of Abies squamata and Sabina squamat were produced following Regional Curve Standardization detrending. The leading principal component of these records is well correlated with the regional summer (JJA) minimum temperature (MinT) (R2 = 0.47, P < 0.001, 1953-2009). Hence we produce a regional summer MinT reconstruction spanning the last 212 years. This reconstruction reveals a long-term persistent warming trend, starting in the 1820s, at a rate of 0.45 ± 0.09 °C/century (1820-2009). This trend is also detected since the 1820s in the Asian summer MinT reconstruction produced by the PAGES 2K project, with a very close warming rate (0.43 ± 0.08 °C/century, 1820-1989). Our record also displays an enhanced multi-decadal variability since the mid-twentieth century. The 1990s-2000s are the warmest of our whole record, due to the superposition of the gradual warming trend and decadal variability during this interval. The strongest decadal cooling occurs during the 1950s and the largest warming trend during the 1970s. The magnitude of warming from 1973 to 2003 was larger than the total warming trend from 1820s to 2009. Extreme events are also more frequent since 1950. The pattern of multi-decadal variability has similarities with the Atlantic multi-decadal oscillation, suggesting common causality. CMIP5 historical simulations fail to capture both the magnitude and timing of this multi-decadal variability. The ensemble CMIP5 average produces a steady warming trend starting in the 1970s, which only accounts for about 60 % of the observed warming trend during this period. We conclude that TP summer temperature could reflect a climate response to increased greenhouse gas concentrations, however modulated by multi-decadal variations common with the Atlantic sector.

Shi, Chunming; Masson-Delmotte, Valérie; Daux, Valérie; Li, Zongshan; Carré, Matthieu; Moore, John C.

2014-10-01

387

Reconstruction of seasonal temperature variability in the tropical Pacific Ocean from the shell of the scallop, Comptopallium radula  

NASA Astrophysics Data System (ADS)

We investigated the oxygen isotope composition (? 18O) of shell striae from juvenile Comptopallium radula (Mollusca; Pectinidae) specimens collected live in New Caledonia. Bottom-water temperature and salinity were monitored in-situ throughout the study period. External shell striae form with a 2-day periodicity in this scallop, making it possible to estimate the date of precipitation for each calcite sample collected along a growth transect. The oxygen isotope composition of shell calcite (? 18O shell calcite) measured at almost weekly resolution on calcite accreted between August 2002 and July 2003 accurately tracks bottom-water temperatures. A new empirical paleotemperature equation for this scallop species relates temperature and ? 18O shell calcite: t(°C)=20.00(±0.61)-3.66(±0.39)×(?18O-?18O) The mean absolute accuracy of temperature estimated using this equation is 1.0 °C at temperatures between 20 and 30 °C. Uncertainties regarding the precise timing of CaCO 3 deposition and the actual variations in ? 18O water at our study sites probably contribute to this error. Comparison with a previously published empirical paleotemperature equation indicates that C. radula calcite is enriched in 18O by ˜0.7‰ relative to equilibrium. Given the direction of this offset and the lack of correlation between shell growth rate and ? 18O shell calcite, this disequilibrium is unlikely to be related to kinetic isotope effects. We suggest that this enrichment reflects (1) a relatively low pH in the scallop's marginal extrapallial fluid (EPF), (2) an isotopic signature of the EPF different from that of seawater, or (3) Rayleigh fractionation during the biocalcification process. Relative changes in ? 18O shell calcite reflect seawater temperature variability at this location and we suggest that the shell of C. radula may be useful as an archive of past seawater temperatures.

Thébault, Julien; Chauvaud, Laurent; Clavier, Jacques; Guarini, Jennifer; Dunbar, Robert B.; Fichez, Renaud; Mucciarone, David A.; Morize, Eric

2007-02-01

388

Free and forced tropical variability: role of the wind-evaporation-sea surface temperature (WES) feedback  

E-print Network

and Shukla, 1996). It is possible that the atmospheric internal noise forces the SST in each hemisphere independently, lowering correlation between inter-hemispheric anomalies (Chang et al., 2001). Okajima et al. (2003) propose that WES feedback is weakened... cross-equatorial anti-symmetry of SSTs at inter-annual time-scales, as was previously suggested (e.g. Moura and Shukla, 1981), but exists as cross equatorial SST gradients (CESG) that result in dipole like anomalies of atmospheric variables 8 (e.g. En...

Mahajan, Salil

2009-05-15

389

Spatial and temporal variability of urban tree canopy temperature during summer 2010 in Berlin, Germany  

NASA Astrophysics Data System (ADS)

Trees form a significant part of the urban vegetation. Their meteorological and climatological effects at all scales in urban environments make them a flexible tool for creating a landscape oriented to the needs of an urban dweller. This study aims at quantifying the spatio-temporal patterns of canopy temperature ( T C) and canopy-to-air temperature difference (? T C) in relation to meteorological conditions and tree-specific (physiological) and urban site-specific characteristics. We observed T C and ? T C of 67 urban trees (18 species) using a high-resolution thermal-infrared (TIR) camera and meteorological measurements in the city of Berlin, Germany. TIR images were recorded at 1-min intervals over a period of 2 months from 1st July to 31st August 2010. The results showed that ? T C depends on tree species, leaf size and fraction of impervious surfaces. Average canopy temperature was nearly equal to air temperature. Species-specific maximum ?T C varied between 1.9 ± 0.3 K ( Populus nigra), 2.9 ± 0.3 K ( Quercus robur), 3.2 ± 0.5 K ( Fagus sylvatica), 3.9 ± 1.0 K ( Platanus acerifolia), 4.6 ± 0.2 K ( Acer pseudoplatanus), 5.0 ± 0.5 K ( A. platanoides) and 5.6 ± 1.1 K ( A. campestre). We analysed ? T C for a hot and dry period (A) and a warm and wet period (B). The range of species-specific ?T C at noon was nearly equal, i.e. 4.4 K for period A and 4.2 K for period B. Trees surrounded by high fraction of impervious surfaces showed consistently higher ? T C. Knowledge of species-specific canopy temperature and the impacts of urban structures are essential in order to optimise the benefits from trees in cities. However, comprehensive evaluation and optimisation should take the full range of climatological effects into account.

Meier, Fred; Scherer, Dieter

2012-12-01

390

Trend of melt under Pine Island Glacier ice shelf modulated by high variability in ocean temperature  

NASA Astrophysics Data System (ADS)

Pine Island Glacier and neighbouring outlet glaciers of West Antarctica have thinned and accelerated over the last 2 decades, significantly contributing to global sea level rise. Increased ocean heat transport beneath Pine Island Glacier ice shelf and unpinning from a seabed ridge are thought to be the primary drivers of such changes. However, the acceleration of the glacier paused since 2009, renewing questions about the main processes presently affecting the ice/ocean system, the future behaviour of the glacier and the associated impacts. Here, we present ocean observations taken in austral Spring 2012 to show a 200 m lowering of the thermocline at the glacier calving front and a 50% decrease of meltwater production from 2009. High-resolution simulations of the ocean circulation in the cavity beneath the floating tongue of the glacier demonstrate that for the present ice geometry, the seabed ridge blocks the warmest deep waters from reaching the ice and strongly ties meltwater production to thermocline depth above the ridge, hereby making it susceptible to relatively high variability in time, from intraseasonal to interannual. These results highlight the role of climatic variability in glacial ice loss and the fundamental importance of local ice shelf and seabed geometry for determining ice-ocean dynamics.

Dutrieux, Pierre; De Rydt, Jan; Jenkins, Adrian; Holland, Paul R.; Ha, Ho Kyung; Lee, Sang Hoon; Povl Abrahamsen, E.; Jacobs, Stanley S.

2013-04-01

391

Spatiotemporal variability of increasing temperature impacts on grassland vegetation along an elevation transect in the Alps  

NASA Astrophysics Data System (ADS)

Different manipulative approaches have been developed to study and quantify impacts of temperature increase on grassland ecosystems. Many of them share the problem of unwanted effects on the surrounding microclimatic conditions. Transplantation of grassland mesocosms along elevation gradients can be a realistic alternative, although with some restrictions. Here we present 3 years of data from a double-transplant-experiment, were 70*70*20cm grassland turves were transplanted at two elevations from 2000m to 1500m a.s.l. and from 1500m to 1000m a.s.l. respectively, along an inner-alpine elevation gradient in the Vinschgau Valley (South Tyrol, I). All donor and receiving sites are comparable regarding land use (meadows), soil conditions or exposition and are located within a few km's distance ensuring comparable weather conditions apart from the intended air temperature (0.54°K/100m) and annual precipitation (20mm/100m) lapse rate. Phytodiversity and above ground net primary production (ANPP) of the transplanted mesocosms were assessed and compared with locally transplanted monoliths of the respective donor site. Furthermore, growth dynamics was continuously observed throughout the vegetation season with a non-destructive method based on measurement of light (photosynthetic active radiation) extinction within the canopy. After 3 years no significant changes in absolute species numbers has been detected at all, whereas slight variations have been observed regarding species composition. Those shifts could be differentiated both to transplantation artifacts and effects of the elevated temperature. Total aboveground phytomass, unsurprisingly, showed higher values on transplanted (lower) mesocosms, however: data from single cuts and growth rate analysis reveal differing effects between the two transplantation steps as well as over the course of the vegetation period. Transplanted plots from 2000m to 1500m showed continuously higher productivity from spring to autumn, whereas on the lower transplants (from 1500m to 1000m) during summer months the temperature benefit gets balanced by higher evapotranspiration rates, resulting in more frequent drought stress. Summarizing, gained experiences confirm well-designed transplant approach to be an interesting alternative for mid- to longterm simulations of future climate conditions in grassland ecosystems. Furthermore, results indicate that the impact of increasing temperatures in the studied grassland highly depends on elevation and acts rather by a prolongation of the vegetation period than by elevated summer temperatures.

Niedrist, Georg; Obojes, Nikolaus; Bertoldi, Giacomo; Della Chiesa, Stefano; Tasser, Erich; Tappeiner, Ulrike

2013-04-01

392

Large-scale sea surface temperature variability from satellite and shipboard measurements  

NASA Technical Reports Server (NTRS)

A series of satellite sea surface temperature intercomparison workshops were conducted under NASA sponsorship at the Jet Propulsion Laboratory. Three different satellite data sets were compared with each other, with routinely collected ship data, and with climatology, for the months of November 1979, December 1981, March 1982, and July 1982. The satellite and ship data were differenced against an accepted climatology to produce anomalies, which in turn were spatially and temporally averaged into two-degree latitude-longitude, one-month bins. Monthly statistics on the satellite and ship bin average temperatures yielded rms differences ranging from 0.58 to 1.37 C, and mean differences ranging from -0.48 to 0.72 C, varying substantially from month to month, and sensor to sensor.

Bernstein, R. L.; Chelton, D. B.

1985-01-01

393

Combined effects of chemical and temperature stress on Chironomus riparius populations with differing genetic variability.  

PubMed

Exposure to pollutants under multiple environmental stressors (e.g., climate change and global warming) and the genetic diversity of populations are suspected to have serious impacts on populations and ecosystems but have only rarely been analysed. In the present study, we investigated the effects of the biocide tributyltin (TBT) within a temperature gradient (17, 20 and 23 degrees C) on life history parameters of a genetically diverse (GEN+) and a highly inbred population (GEN-) of the midge Chironomus riparius. While endpoints, mortality and reproduction parameters were considered, the population growth rate as an integrative endpoint was determined. We found severe effects for GEN-, indicating that populations with lower genetic diversity are more endangered by combined stressors such as increasing temperature and chemical pollution compared to genetically diverse populations. PMID:19827487

Oetken, Matthias; Jagodzinski, Lucas S; Vogt, Christian; Jochum, Adrienne; Oehlmann, Jörg

2009-08-01

394

Long-term changes and spatio-temporal variability of the growing season temperature in Europe during the last Millennium  

NASA Astrophysics Data System (ADS)

A gridded reconstruction of April to September temperature was produced for Europe based on tree-rings, documentaries, pollen and ice cores. The majority of the proxy series have an annual resolution. For a better inference of long-term climate variations, they were completed by number of low resolution data (decadal or more), mostly on pollen and ice-core data. An original spectral analogue method was devised to deal with this heterogeneous dataset, and especially to preserve the long-term variations and the variability of the temperature series. It is the condition is to make pertinent the comparison of the recent climate changes to a broader context of 1400 years. The reconstruction of the April-September temperature was validated with a Jack-knife technique, and it was also compared with other spatially gridded temperature reconstructions, literature data, and glacier advance and retreat curves. We also attempted to relate the spatial distribution of European temperature anomalies to known solar and volcanic forcings. We found that (1) our results are sound back to A.D. 750; (2) conditions during the last decade have exceeded all those known during the last millennium; (3) before the 20th century, cold periods can partly be explained by low solar activity and/or high volcanic activity and that Medieval Warm Period (MWP) is consistent with a high solar activity; (4) during the 20th century, however only anthropogenic forcing can explain the exceptionally high temperature rise; (5) based on an analysis of the distribution of extreme temperatures, the maximum event of the Medieval Period (1.1°C higher than the 1960-1990 reference period) had a return period of more than 1000 years, but this recently fell to less than 26 years; (6) all decades before AD 1350 were warm on average but relatively heterogeneous, while the last decade was homogeneously warmer. These results support the fact that we are facing an unprecedented changing climate in Europe unlike any known in the last 1000 years, as pointed out previously. The new result is that this anthropogenic change is characterised by spatial homogeneity and changes as well in average temperatures than in distribution of extreme events, while natural climate forcings induce warm periods with heterogeneous spatial patterns and less frequent extreme events. This study demonstrates that recent changes in temperature differ substantially from temperature changes reconstructed in the past and are well in excess of normal variations experienced in previous centuries and caused by natural forcings.

Guiot, Joel; Corona, Christophe

2010-05-01

395

The vertical variability of hyporheic fluxes inferred from riverbed temperature data  

NASA Astrophysics Data System (ADS)

We present detailed profiles of vertical water flux from the surface to 1.2 m beneath the Haughton River in the tropical northeast of Australia. A 1-D numerical model is used to estimate vertical flux based on raw temperature time series observations from within downwelling, upwelling, neutral, and convergent sections of the hyporheic zone. A Monte Carlo analysis is used to derive error bounds for the fluxes based on temperature measurement error and uncertainty in effective thermal diffusivity. Vertical fluxes ranged from 5.7 m d-1 (downward) to -0.2 m d-1 (upward) with the lowest relative errors for values between 0.3 and 6 m d-1. Our 1-D approach provides a useful alternative to 1-D analytical and other solutions because it does not incorporate errors associated with simplified boundary conditions or assumptions of purely vertical flow, hydraulic parameter values, or hydraulic conditions. To validate the ability of this 1-D approach to represent the vertical fluxes of 2-D flow fields, we compare our model with two simple 2-D flow fields using a commercial numerical model. These comparisons showed that: (1) the 1-D vertical flux was equivalent to the mean vertical component of flux irrespective of a changing horizontal flux; and (2) the subsurface temperature data inherently has a "spatial footprint" when the vertical flux profiles vary spatially. Thus, the mean vertical flux within a 2-D flow field can be estimated accurately without requiring the flow to be purely vertical. The temperature-derived 1-D vertical flux represents the integrated vertical component of flux along the flow path intersecting the observation point. This article was corrected on 6 JUN 2014. See the end of the full text for details.

Cranswick, Roger H.; Cook, Peter G.; Shanafield, Margaret; Lamontagne, Sebastien

2014-05-01

396

Aircraft observations of sea surface temperature variability in the tropical Pacific  

Microsoft Academic Search

During the southern summer of 1992-1993, a series of aircraft observations of sea surface temperature (SST) were obtained over the tropical western Pacific ocean as part of the Tropical Ocean Global Atmosphere Coupled Ocean-Atmosphere Response Experiment (TOGA COARE). Down-looking thermal infrared (10-11 mum) observations of the sea surface, coincident with uplooking infrared observations (9-11 mum) and meteorological measurements from the

Denise Hagan; David Rogers; Carl Friehe; Robert Weller; Edward Walsh

1