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1

Examining past temperature variability in Moosonee, Thunder Bay, and Toronto, Ontario, Canada through a day-to-day variability framework  

NASA Astrophysics Data System (ADS)

Temperature variability in Moosonee, Thunder Bay, and Toronto, Ontario, Canada is examined through a day-to-day variability framework. Statistical measures used in this study include standard deviation (SD), day-to-day temperature variability (DTD), DTD/SD ratio ( G), change in day-to-day variability (?DTD), and threshold measures of 5°C and 10°C. ?DTD is the difference between day-to-day change in temperature maximum (DTDtmax) and day-to-day change in temperature minimum (DTDtmin). A distinct seasonal trend is reflected in DTD in Moosonee, Thunder Bay, and Toronto, where ?DTD is greatest during spring. Monthly ?DTD averages in Toronto, Thunder Bay, and Moosonee are affected by seasonal variation, the lake effect, and the freeze-up of nearby waterbodies. Yearly averages of ?DTD have significantly increased over the past recent years in Moosonee and Thunder Bay; a continual increase in climate variability may be detrimental to the subsistence lifestyle of those living in these areas.

Tam, Benita Y.; Gough, William A.

2012-10-01

2

Description of Day-to-Day Variability in IRI  

NASA Astrophysics Data System (ADS)

The International Reference Ionosphere (IRI) describes the monthly average behavior of Earth's ionosphere based on most of the accessible and reliable ground and space observations of ionospheric parameters. IRI is doing an excellent job in accurately representing these average conditions as countless comparisons with additional data have shown and as acknowledged by the fact that international organizations (COSPAR, URSI, ISO, ECSS) have accepted IRI as their ionosphere standard. However, with our ever-increasing dependence on space technology it has become important to go beyond the monthly averages and to provide a description of the day-to-day variability of the ionosphere. We will review past and ongoing efforts to provide IRI users with a quantitative description of ionospheric variability depending on altitude, time of day, time of year, latitude and solar and magnetic activity. We will present new results from an analysis of ISIS and Alouette topside sounder data. The IRI team is also pursuing the development of an IRI Real-Time (IRI-RT) that uses assimilative algorithms or updating procedures to combine IRI with real-time data for a more accurate picture of current ionospheric conditions. We will review the status of these activities and report on latest results.

Bilitza, Dieter; Liu, Boding; Rodriguez, Joseph E.

2013-04-01

3

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

NASA Technical Reports Server (NTRS)

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

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

1987-01-01

4

Quantification of day-to-day variability in growth hormone levels in acromegaly.  

PubMed

Growth hormone (GH) measurements are routinely used for important treatment decisions in patients with acromegaly, yet their reliability is affected by numerous factors including assay precision and variability, sampling intensity, and hormone pulsatility. The day-to-day variation in GH in acromegaly has not been studied. This study quantified the magnitude of day-to-day GH variability in patients with acromegaly by performing an analysis of previously obtained plasma GH profiles. The analysis was performed at the Michigan Clinical Research Unit at the University of Michigan. A total of nine 48 h Q10 min GH profiles obtained in nine patients with active acromegaly were examined. The study was planned after data collection and analysis was conducted using Altman-Bland methods. Day 1 vs. Day 2 values were examined. 95% confidence intervals of the D2 vs. D1 ratios were calculated on all individual subject data as well as on a single 0800 h GH sample and composite mean data for 2-, 5-, 9-, and 24-h sampling protocols. Confidence interval range was 0.66-1.50 for the 0800 h sample and was similar for all sampling protocols except somewhat more narrow for the 24-h sampling (0.75-1.32). Daily variations in GH levels introduce an additional confounding element when using a single GH level or even daily GH curves to assess a patient's GH milieu. It may have an impact on result interpretation and subsequent treatment decisions especially when GH results are considered borderline. PMID:20697817

Kraftson, Andrew; Barkan, Ariel

2010-12-01

5

Day to day and longitudinal variability of the nighttime low latitude terrestrial ionosphere  

NASA Astrophysics Data System (ADS)

The Earth's ionosphere is the region of upper atmosphere that is a partially ionized gas. It extends from the mesosphere and through the thermosphere to altitudes ˜1000 km where it ultimately merges with the magnetosphere. The strong coupling of the ionosphere to the dense regions below and the solar-driven magnetosphere above make it the most variable component of the atmosphere. Sources of ionospheric variability or "weather" originate from solar and geomagnetic activity and meteorological influences. One motivation for studying the ionosphere is to improve techniques to predict ionospheric weather that affects space-borne and ground-based technological systems used for communication, navigation, surveillance and basic research. Geomagnetic storms can be particularly disruptive leading to significant satellite systems failures. Even quiet-time disturbances, such as scintillation and spread-F events, can impact high frequency radio communications, especially in the equatorial and high-latitude regions. To improve prediction capabilities, a better understanding of the drivers of the variability is needed. In this study we used recent ionospheric measurements, particularly remote ultraviolet (UV) sensing of the airglow, along with recently developed analysis techniques to better characterize the day to day and longitudinal variability of the nighttime low-latitude ionosphere and to advance the understanding of the origins of such variations. We performed a case study of the longitudinal variability in the occurrence of equatorial scintillation on 22-23 March 2002 and found evidence of longitudinal differences in the daytime and evening vertical plasma drifts that may affect the conditions for the occurrence of scintillation. This work prompted an investigation the day to day variability of the nighttime ionosphere using UV remote sensing data from the Low Resolution Airglow and Aurora Spectrograph (LORAAS). UV limb scans from March 2001 and March 2002 were used to determine the density and morphology of the post-midnight (˜0230 LT) Equatorial Anomaly (EA), a prominent feature of the nighttime ionosphere. The most variable feature was the latitude and separation of the EA crests (46-67% variation about the mean). The least variable was the height of the peak densities in the EA crests (<10% variation about the mean). The monthly mean values of the EA features are in agreement with the International Reference Ionosphere (IRI-90), a climatology model. We used the LORAAS data along with a physics-based model of the ionosphere (SAMI2) to investigate a wavelike pattern in the longitudinal variation of ionospheric densities in the EA region. We discovered a pronounced hemispheric asymmetry in the longitudinal variations of the EA crests and showed that this is due to both longitudinally varying thermospheric winds and effects associated with the offset of the geographic and geomagnetic equators.

McDonald, Sarah E.

6

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

PubMed

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

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

2010-06-01

7

Day-to-Day Variability of Median Nerve Location within the Carpal Tunnel  

PubMed Central

Background Carpal tunnel syndrome is a commonly encountered entrapment disorder resulting from mechanical insult to the median nerve. MRI-based investigations have documented typical locations of the median nerve within the carpal tunnel; however, it is unclear whether those locations are consistent within an individual on different days. Methods To determine the day-to-day variability of nerve location, 3.0T MRI scans were acquired from six normal volunteers over multiple sessions on three different days. Half of the scans were acquired with the wrist in neutral flexion and the fingers extended, and the other half were acquired with the wrist in 35 degrees of flexion and the fingers flexed. Prior to half of the scans (in both poses), subjects performed a preconditioning routine consisting of specified hand activities and several repetitions of wrist flexion/extension. The shape, orientation, location, and location radius of variability of the median nerve and three selected flexor tendons were determined for each subject and compared between days. Findings Two of the six subjects had substantial variability in nerve location when the wrist was in neutral, and four of the subjects had high variability in nerve position when the wrist was flexed. Nerve variability was typically larger than tendon variability. The preconditioning routine did not decrease nerve or tendon location variability in either the neutral or the flexed wrist positions. Interpretation The high mobility and potential for large variability in median nerve location within the carpal tunnel needs to be borne in mind when interpreting MR images of nerve location. PMID:20605292

Goetz, Jessica E.; Thedens, Daniel R.; Kunze, Nicole M.; Lawler, Ericka A.; Brown, Thomas D.

2010-01-01

8

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

Microsoft Academic Search

Inter-day training reliability and variability in artistic gymnastics vaulting was determined using a customised infra-red timing gate and contact mat timing system. Thirteen Australian high performance gymnasts (eight males and five females) aged 11–23 years were assessed during two consecutive days of normal training. Each gymnast completed a number of vault repetitions per daily session. Inter-day variability of vault run-up

Elizabeth Bradshaw; Patria Hume; Mark Calton; Brad Aisbett

2010-01-01

9

Day to day variability of h?F and foF2 during some solar cycle epochs  

NASA Astrophysics Data System (ADS)

Comparison of the diurnal and seasonal changes of the variability (VR) of the virtual height of reflection (h?F) and those of critical frequency of the F layer (foF2) is carried out at Ibadan (7.4°N, 3.9°E, 6°S dip) in the African sector. The effect of latitude on both characteristics is investigated by combining data from Singapore (1.3°N,103.8°E, 17.6°S dip) in the East Asian sector and Slough (51.5°N, 359.4°E, 66.5°S dip) in the European sector. The variability of foF2 is found greater than that of h?F except during high solar activity when night-time h?F VR is about the same as night-time foF2 VR possibly due to high post-sunset rise in F region heights at this epoch. Both characteristics have pre-midnight and post-midnight peaks with the latter being the greater one at all epochs with the exception of all the seasons of 1958 but June Solstice, very likely because of the same greater F region height during maximum solar activity. Night-time foF2 VR is greater in September Equinox and June Solstice at all epochs while night-time h?F VR is greater in June Solstice during the three epochs, on a general note. No seasonal trend is observed in the daytime variability of both characteristics during the three epochs except for h?F VR of December Solstice during high solar activity, which is greater than those of other seasons. VR of both parameters are found to increase and decrease alternately with Zurich sunspot number (Rz) at Ibadan and Singapore throughout the day. VR of foF2 at Slough is found to increase from midnight to 1300 h after which it alternates. Generally, post-midnight VR of both characteristics are greater than those of pre-midnight at low latitudes during all epochs while daytime VR are the least. At the mid-latitude station of Slough, foF2 VR is about the same throughout the hours of the day during 1968 and 1971, its post-midnight value is however greater than those of pre-midnight and daytime during 1970. Daytime h?F VR is greater than post- and pre-midnight values during 1968, but about the same throughout the hours of the day during 1971.

Somoye, E. O.; Akala, A. O.; Ogwala, A.

2011-08-01

10

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

11

An analysis of the quiet time day-to-day variability in the formation of postsunset equatorial plasma bubbles in the Southeast Asian region  

NASA Astrophysics Data System (ADS)

Presented is an analysis of the occurrence of postsunset Equatorial Plasma Bubbles (EPBs) detected using a Global Positioning System (GPS) receiver at Vanimo. The three year data set shows that the EPB occurrence maximizes (minimizes) during the equinoxes (solstices), in good agreement with previous findings. The Vanimo ionosonde station is used with the GPS receiver in an analysis of the day-to-day EPB occurrence variability during the 2000 equinox period. A superposed epoch analysis (SEA) reveals that the altitude, and the change in altitude, of the F layer height is ˜1 standard deviation (1?) larger on the days for which EPBs were detected, compared to non-EPB days. These results are then compared to results from the Thermosphere Ionosphere Electrodynamics General Circulation Model (TIEGCM), which show strong similarities with the observations. The TIEGCM is used to calculate the flux-tube integrated Rayleigh-Taylor (R-T) instability linear growth rate. A SEA reveals that the modeled R-T growth rate is 1? higher on average for EPB days compared to non-EPB days, and that the upward plasma drift is the most dominant contributor. It is further demonstrated that the TIEGCM's success in describing the observed daily EPB variability during the scintillation season resides in the variations caused by geomagnetic activity (as parameterized by Kp) rather than solar EUV flux (as parameterized by F10.7). Geomagnetic activity varies the modeled high-latitude plasma convection and the associated Joule heating that affects the low-latitude F region dynamo, and consequently the equatorial upward plasma drift.

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

2014-04-01

12

Day-to-day stationary link flow pattern  

Microsoft Academic Search

Day-to-day traffic dynamics aim at modeling driver’s day-to-day learning and behavior adjustment process and providing insight on how the traffic flow pattern evolves over time. A number of continuous-time path flow dynamics have been proposed and studied in the literature whose stationary path flow pattern coincides with user equilibrium. However, the application prospects of these findings are limited by the

Fan Yang; Ding Zhang

2009-01-01

13

On the day-to-day variation of the equatorial electrojet during quiet periods  

NASA Astrophysics Data System (ADS)

It has been known for a long time that the equatorial electrojet varies from day to day even when solar and geomagnetic activities are very low. The quiet time day-to-day variation is considered to be due to irregular variability of the neutral wind, but little is known about how variable winds drive the electrojet variability. We employ a numerical model introduced by Liu et al. (2013), which takes into account weather changes in the lower atmosphere and thus can reproduce ionospheric variability due to forcing from below. The simulation is run for May and June 2009. Constant solar and magnetospheric energy inputs are used so that day-to-day changes will arise only from lower atmospheric forcing. The simulated electrojet current shows day-to-day variability of ±25%, which produces day-to-day variations in ground level geomagnetic perturbations near the magnetic equator. The current system associated with the day-to-day variation of the equatorial electrojet is traced based on a covariance analysis. The current pattern reveals return flow at both sides of the electrojet, in agreement with those inferred from ground-based magnetometer data in previous studies. The day-to-day variation in the electrojet current is compared with those in the neutral wind at various altitudes, latitudes, and longitudes. It is found that the electrojet variability is dominated by the zonal wind at 100-120 km altitudes near the magnetic equator. These results suggest that the response of the zonal polarization electric field to variable zonal winds is the main source of the day-to-day variation of the equatorial electrojet during quiet periods.

Yamazaki, Y.; Richmond, A. D.; Maute, A.; Liu, H.-L.; Pedatella, N.; Sassi, F.

2014-08-01

14

Day-to-day variations of temperature in Texas  

E-print Network

in Janua~ Total 0 1 2 3 4 5 6 7 8 9 10 Abilene FofM 6 FofE 0 Brown sville FofdI 18 FofE 0 Del Rio F of M 18 FofE 5 9 20 7 20 6 14 4 7 5 20 8 17 8 19 5 13 5 18 6 18 7 22 6 16 7 26 5 20 7 22 2 19 4 22 10 29 4 10 5 9 9 20 7 9 110 106 2 16 7 10... in Janua~ Total 0 1 2 3 4 5 6 7 8 9 10 Abilene FofM 6 FofE 0 Brown sville FofdI 18 FofE 0 Del Rio F of M 18 FofE 5 9 20 7 20 6 14 4 7 5 20 8 17 8 19 5 13 5 18 6 18 7 22 6 16 7 26 5 20 7 22 2 19 4 22 10 29 4 10 5 9 9 20 7 9 110 106 2 16 7 10...

Breese, Richard Preston

2012-06-07

15

Immunomodulators in day to day life: a review.  

PubMed

There are ongoing trends of immunomodulation to combat a vast range of human and animal diseases including the incurable diseases like viral diseases, cancers, autoimmune diseases and inflammatory conditions. Animate as well as non-animate factors, surrounding us are interacting with our immune system. A balanced diet should contain all essential components from energy to vitamin and trace minerals. Each of these constituent has a very special effect on the immune system starting from their development to active role in immunity therefore, the outcome of their deficiency often ends in disease. Edible items which we consume like various vegetables, spices, herbs, fruits etc., are also equally responsible in manipulation of our system either in positive or negative way. Water has biggest share in our body and acts as the main medium to support the activities of the different system of body without exception of immune system. Proper environmental temperature is essential to maintain body's functions and experiments carried out regarding the effect of temperature suggest that extremes of the temperature are often cause immunosuppression directly by acting on the cells of immunity or indirectly through inducing stress and thereby increasing production of catecholamine which are potent anti-immune molecules. Various pathogenic as well as non-pathogenic bacteria cause immune suppression and immune potentiation, respectively. Proper exercise hold a prime position in the healthy life as it supports immunity and keeps disease away. The present review deals with all these immunomodulators having both positive and negative impact on the health status of an individual. PMID:24498836

Mahima; Ingle, Abhijeet M; Verma, Amit Kumar; Tiwari, Ruchi; Karthik, K; Chakraborty, Sandip; Deb, Rajib; Rajagunalan, S; Rathore, Rajesh; Dhama, Kuldeep

2013-09-01

16

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

17

variability temperature  

E-print Network

sea ocean surface variability temperature pacific atlantic climate north tropical data globalmodel seasurface sst forcing enso equatorial change southern cloud temperatures oscillation rainfall variations largescale multidecadal prediction record relation simulation clouds distribution last mixed oceanatmosphere

18

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

ERIC Educational Resources Information Center

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

Clydesdale, Greg; Tan, John

2009-01-01

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

The effects of day-to-day variability of physiological data on operator functional state classification.  

PubMed

The application of pattern classification techniques to physiological data has undergone rapid expansion. Tasks as varied as the diagnosis of disease from magnetic resonance images, brain-computer interfaces for the disabled, and the decoding of brain functioning based on electrical activity have been accomplished quite successfully with pattern classification. These classifiers have been further applied in complex cognitive tasks to improve performance, in one example as an input to adaptive automation. In order to produce generalizable results and facilitate the development of practical systems, these techniques should be stable across repeated sessions. This paper describes the application of three popular pattern classification techniques to EEG data obtained from asymptotically trained subjects performing a complex multitask across five days in one month. All three classifiers performed well above chance levels. The performance of all three was significantly negatively impacted by classifying across days; however two modifications are presented that substantially reduce misclassifications. The results demonstrate that with proper methods, pattern classification is stable enough across days and weeks to be a valid, useful approach. PMID:21840403

Christensen, James C; Estepp, Justin R; Wilson, Glenn F; Russell, Christopher A

2012-01-01

21

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

22

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

PubMed Central

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

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

2014-01-01

23

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

PubMed Central

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

Luft, Janis; Grady, Deborah; Kuppermann, Miriam

2009-01-01

24

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

NASA Astrophysics Data System (ADS)

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

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

1996-04-01

25

A stimulus-response model of day-to-day network dynamics  

Microsoft Academic Search

A general structure of stimulus-response formula is presented to specify the interacted network dynamics under the assumption of a daily learning and adaptive travel behavior. By taking the time derivative of system variable as a response term, the evolution is formulated as a dynamic system. Issues of exis- tence, uniqueness, and stability for the proposed differential equa- tions are briefly

Hsun-jung Cho; Ming-chorng Hwang

2005-01-01

26

Imposing OrderA Process to Manage Day-to-Day Activities in Two-Earner Families With Preschool Children  

Microsoft Academic Search

This study investigated how English and Canadian families with preschool children used strategies to impose varying levels of order to manage day-to-day activities. This grounded theory study is a secondary analysis of 55 hours of participant observation and interviews with 58 individuals and 29 couples. Constant comparative analysis and theoretical sampling were used to construct categories. To attempt to impose

Wendy A. Hall

2007-01-01

27

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

28

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

Microsoft Academic Search

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

Chantal Levesque; Kirk Warren Brown

2007-01-01

29

Day-to-day variability of Spread-F occurrence in the Brazilian sector during low solar activity  

NASA Astrophysics Data System (ADS)

Spread-F at equatorial and low latitude is usually related with large-scale equatorial irregularities. These large-scale equatorial irregularities are generated in the bottom side of the equatorial F-region just after sunset and are nearly aligned along the Earth's magnetic field lines. As soon as irregularities reach higher altitudes in the equatorial region, it grows poleward, due to the high conductivity along the magnetic field. Then, after sometime, these irregularities can be observed at low latitude. In this work, we present and discuss observations of the occurrence, formation, and evolution of spread-F over the Brazilian sector under low solar activity condition. This study was carried out using two ionosonde stations, almost aligned to the same magnetic meridian, Palmas (10.2 S, 48.2 W; dip latitude 5.7 S, hereafter referred as PAL) and Sao Jose dos Campos (23.2 S, 45.9 W; dip latitude 17.6 S, hereafter referred as SJC). In addition, complementary data from OI 630 nm nightglow emission and TEC (GPS) were used to help to undusted some unusual cases.

Fagundes, P. R.

2012-12-01

30

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

31

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

PubMed

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

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

2014-03-01

32

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

33

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

PubMed Central

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

Fogel, Alan

2013-01-01

34

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

SciTech Connect

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

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

2006-07-01

35

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

PubMed Central

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

2014-01-01

36

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

37

Sea Surface Temperature Variability: Patterns  

E-print Network

Words ocean-atmosphere interaction, El Ni~no, Pacific Decadal Oscillation, Atlantic Multidecadal associated with the North Atlantic Oscillation, and a pan-Pacific mode known as the Pacific Decadal, patterns of SST variability may arise from intrinsic oceanic modes, notably the Atlantic Multidecadal

Hurrell, James

38

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

39

Variable temperature semiconductor film deposition  

DOEpatents

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

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

1998-01-01

40

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

41

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

42

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

43

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

44

Sea surface temperature variability: patterns and mechanisms.  

PubMed

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

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

2010-01-01

45

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; S?rensen, Lene; Thougaard, Britta; Lindberg, Lone; Bech, Per

2013-01-01

46

Scanning electrochemical microscopy at variable temperatures.  

PubMed

All chemical reactions are influenced by temperature, however, temperature is usually not considered an important parameter which has to be varied or at least controlled in SECM measurements. A precise temperature-control unit was designed and integrated into a SECM setup which allows setting the temperature of the sample and the adjacent electrolyte in a range between 0 and 100 °C without causing convection. Data acquisition was synchronized with the current pulses through the Peltier element to decrease the noise and keep the tip-to-sample distance constant during imaging. SECM images in the feedback mode, generator collector mode and the redox competition mode for model samples such as an enzyme entrapped within a polymer spot or oxygen reduction catalysts demonstrate the importance of controlling temperature as well as performing SECM experiments at predefined and constant increased temperature. PMID:23348196

Schäfer, Dominik; Puschhof, Andrea; Schuhmann, Wolfgang

2013-04-14

47

Temperature and size variabilities of the Western Pacific Warm Pool  

NASA Technical Reports Server (NTRS)

Variabilities in sea-surface temperature and size of the Western Pacific Warm Pool were tracked with 10 years of satellite multichannel sea-surface temperature observations from 1982 to 1991. The results show that both annual mean sea-surface temperature and the size of the warm pool increased from 1983 to 1987 and fluctuated after 1987. Possible causes of these variations include solar irradiance variabilities, El Nino-Southern Oscillaton events, volcanic activities, and global warming.

Yan, Xiao-Hai; Ho, Chung-Ru; Zheng, Quanan; Klemas, Vic

1992-01-01

48

Predation life history responses to increased temperature variability.  

PubMed

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

49

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

50

Contribution of solar radiation to decadal temperature variability over land.  

PubMed

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

2013-09-10

51

Contribution of solar radiation to decadal temperature variability over land  

NASA Astrophysics Data System (ADS)

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.

Wang, Kaicun; Dickinson, Robert

2014-05-01

52

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

53

THE MULTI-USE STEINEL VARIABLE TEMPERATURE  

E-print Network

. This Heat Gun operates at 1100° F with no visual indication of temperature (no flame). The hot airstream at the outlet nozzle will bum flesh. Do not tum on Heat Gun with hand in front of nozzle. DO NOT USE NEAR Voltage 120 VAC Air Flow 14.8 cubic feet/minute Amps 12.5 Cautions 1. This heat gun can produce up to 1100

Kleinfeld, David

54

THE MULTI-USE STEINEL VARIABLE TEMPERATURE  

E-print Network

. This Heat Gun operates at 1100° F with no visual indication of temperature (no flame). The hot airstream at the outlet nozzle will bum flesh. Do not tum on Heat Gun with hand in front of nozzle. DO NOT USE NEAR Voltage 120 V AC Air Flow 14.8 cubic feet/minute Amps 12.5 Cautions 1. This heat gun can produce up

Kleinfeld, David

55

Interpolation of climate variables and temperature modeling  

Microsoft Academic Search

Geographic Information Systems (GIS) and modeling are becoming powerful tools in agricultural research and natural resource\\u000a management. This study proposes an empirical methodology for modeling and mapping of the monthly and annual air temperature\\u000a using remote sensing and GIS techniques. The study area is Gangetic West Bengal and its neighborhood in the eastern India,\\u000a where a number of weather systems

Sailesh Samanta; Dilip Kumar Pal; Debasish Lohar; Babita Pal

2011-01-01

56

Pattern Variability in Arctic Air Temperature Records  

NASA Astrophysics Data System (ADS)

The goal of this paper is to provide an overview of recent progress regarding the acquisition and processing of surface air temperature data in the Arctic. It highlights potential methodological contributions to the identification and characterization of pattern change, focusing on spatial and temporal correlations and scale-symmetry properties of time series. The presented methods include L-moments, climate network analysis, detrended fluctuations analysis, and Haar wavelet analysis. New results concerning data from high-latitude Arctic stations illustrate some of the presented methodological aspects.

Suteanu, Cristian

2014-09-01

57

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

58

On forced temperature changes, internal variability, and the AMO  

NASA Astrophysics Data System (ADS)

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

59

Multilevel analysis of spatial temperature variability in Brno region  

Microsoft Academic Search

Urban climate is typical with changes in temperature regime compared to rural landscape. This is related to e.g. prevalence of artificial surfaces or production of anthropogenic heat. An Urban Heat Island can be a typical demonstration of urban climate. Temperature variability in urban environment can be studied on different levels using different data sources such as standard meteorological measurements, special-purpose

P. Dobrovolný; R. Brázdil; L. Krahula

2010-01-01

60

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

61

Attributing Future Changes in Surface Temperature Variability to Thermal Advection  

NASA Astrophysics Data System (ADS)

Assessing the projected changes in variability of surface temperature is a key step towards assessing the future probability of extreme events such as cold spells and heat waves. Furthermore, understanding the driving mechanisms behind such changes in variability enables more confidence to be placed in model projections. A large fraction of present day temperature variance is associated with thermal advection, as anomalous winds blow across the land-sea temperature contrast for instance. This study investigates the extent to which this mechanism may also explain projected changes in temperature variability up to the end of the 21st century. Under greenhouse gas forcing there is expected to be an increase in land-sea temperature contrasts in summer and a decrease in winter. In winter, the northern hemisphere will also see decreased large scale meridional temperature gradients due to Arctic amplification of the warming signal. In this study, it is found that the associated changes in thermal advection are expected to lead to widespread changes in daily and monthly temperature variability by the end of the twenty-first century. The study uses a multiple regression analysis applied to ESSENCE, a 17 member ensemble of the ECHAM5/MPI-OM climate model, to separate the contributions from changing temperature gradients and changing circulation patterns. It will be shown that many changes can be explained using only the changes in seasonal mean temperature gradient. A comparison with the CMIP5 suite of models will also be presented to highlight which changes in variability are robust across climate models, and to demonstrate the temporal evolution of the variability signal in model projections.

Ely, Caroline; Woollings, Tim; de Vries, Hylke; Hawkins, Ed

2014-05-01

62

Listeria monocytogenes fecal shedding in dairy cattle shows high levels of day-to-day variation and includes outbreaks and sporadic cases of shedding of specific L. monocytogenes subtypes  

Microsoft Academic Search

Fecal shedding of Listeria monocytogenes poses a risk for contamination of animal feed and agricultural environments and raw food at the pre-harvest stages of food production. To be able to reduce these risks it is critical to improve understanding of the epidemiology of L. monocytogenes shedding in feces. The objective of this study was to assess the daily variability of

A. J. Ho; R. Ivanek; Y. T. Gröhn; K. K. Nightingale; M. Wiedmann

2007-01-01

63

Possible influence of solar radiation variability on the stratosphere temperature  

NASA Astrophysics Data System (ADS)

Using daily temperature data available from radiosonde measurements over Barajas (Madrid), La Coruna, and Palma de Mallorca stations for the time span 1971-1982 and an altitude range 100-30 mb, temperatures at different levels are compared with the 10.7-cm flux in order to check whether radiation variability must be included in lower-stratospheric models. At the latitude studied, stratospheric temperatures are uninfluenced by sudden warming phenomena, avoiding difficulties of masking found in previous studies.

Cacho, J.; Gil, M.; Sainz de Aja, M. J.; Alberca, L. F.

64

Interdiurnal temperature variability over the conterminous United States and Canada  

E-print Network

the mean interdiurnal temperature vari- ability (MITV) of maximum, minimum, or mean temperature for this period. The periods usually chosen in climatological studies are the twelve months, and when the n-I values characterizing a particular month of n... required to obtai n stability of means . They both determined that periods of rapidly changing warm and cold air masses are associated with large mean interdiurnal temperature variability. Landsberg chose a five-year period, 1957-1961, based on Ca...

Rice, Peter Bruce

2012-06-07

65

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

66

No increase in global temperature variability despite changing regional patterns.  

PubMed

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

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

2013-08-15

67

Causes of Greenland temperature variability over the past 4000 years  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

68

Listeria monocytogenes fecal shedding in dairy cattle shows high levels of day-to-day variation and includes outbreaks and sporadic cases of shedding of specific L. monocytogenes subtypes.  

PubMed

Fecal shedding of Listeria monocytogenes poses a risk for contamination of animal feed and agricultural environments and raw food at the pre-harvest stages of food production. To be able to reduce these risks it is critical to improve understanding of the epidemiology of L. monocytogenes shedding in feces. The objective of this study was to assess the daily variability of fecal shedding and its association with individual animal (lactation number and the day of current lactation) and environmental (feed) risk factors. That was achieved by application of longitudinal daily sample collection in a herd of dairy cattle and molecular characterization of isolated L. monocytogenes. Fecal samples (25) and silage samples (2) were collected daily during two 2-week periods and one 5-day period. L. monocytogenes was isolated from 255 out of 825 (31%) fecal samples on 24 out of 33 (73%) days, and from 25 out of 66 (38%) silage samples on 16 out of 33 (48%) days. Ninety-four percent of cows excreted L. monocytogenes in feces at least once during the study period. Our data analyses indicated that (i) the prevalence and incidence risk of L. monocytogenes fecal shedding in cattle vary considerably over time, from 0 to 100%, and both are associated with contamination of silage, (ii) L. monocytogenes fecal shedding in cattle could occur as part of an outbreak or as an isolated sporadic case, (iii) L. monocytogenes subtypes associated with human infections are commonly isolated from cattle feces and silage, and (iv) a single cow can harbor more than one L. monocytogenes subtype on any given day. Although limited to a single dairy cattle herd, these findings provide a significant advancement in the understanding of the epidemiology of L. monocytogenes fecal shedding in dairy cattle. PMID:17481754

Ho, A J; Ivanek, R; Gröhn, Y T; Nightingale, K K; Wiedmann, M

2007-08-16

69

General Characteristics of Temperature and Humidity Variability on Kilimanjaro, Tanzania  

E-print Network

General Characteristics of Temperature and Humidity Variability on Kilimanjaro, Tanzania W. J from loggers ranging in elevation from 1890 to 5800 m a.s.l. up the southwestern slope of Kilimanjaro the gradient and the snow-ice line enhancing it. On average, moisture availability (both relative humidity

Massachusetts at Amherst, University of

70

Novel Dodecaarylporphyrins: Synthesis and Variable Temperature NMR Studies  

SciTech Connect

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

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

1999-05-05

71

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

72

Rheological modelling of physiological variables during temperature variations at rest  

NASA Astrophysics Data System (ADS)

The evolution with time of cardio-respiratory variables, blood pressure and body temperature has been studied on six males, resting in semi-nude conditions during short (30 min) cold stress exposure (0°C) and during passive recovery (60 min) at 20°C. Passive cold exposure does not induce a change in HR but increases VO 2, VCO 2 Ve and core temperature T re, whereas peripheral temperature is significantly lowered. The kinetic evolution of the studied variables was investigated using a Kelvin-Voigt rheological model. The results suggest that the human body, and by extension the measured physiological variables of its functioning, does not react as a perfect viscoelastic system. Cold exposure induces a more rapid adaptation for heart rate, blood pressure and skin temperatures than that observed during the rewarming period (20°C), whereas respiratory adjustments show an opposite evolution. During the cooling period of the experiment the adaptative mechanisms, taking effect to preserve core homeothermy and to obtain a higher oxygen supply, increase the energy loss of the body.

Vogelaere, P.; de Meyer, F.

1990-06-01

73

Temperature variable long path cell for absorption measurements  

NASA Technical Reports Server (NTRS)

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

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

1987-01-01

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

Creativite au jour le jour (Creativity from Day to Day).  

ERIC Educational Resources Information Center

Describes 11 classroom activities used in an adult French program that emphasize the development of linguistic skills, knowledge, and communicative skills. The activities include games, simulation, storytelling, writing of a pastiche based on a Prevert poem, a question-asking exercise, and conversation improvisation. (MSE)

Villarroel, Marie Christine

1985-01-01

76

Optimizing the Day to Day Operation of Utility Systems  

E-print Network

At the 2002 IETC, Linnhoff March presented an overview of spreadsheet-based software packages to rigorously model site utility systems. Such models allow the user to plan future scenarios that might impact upon the system operation (energy saving...

Eastwood, A.; Bealing, C.

77

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

78

Monofractal nature of air temperature signals reveals their climate variability  

E-print Network

We use the discrete "wavelet transform microscope" to show that the surface air temperature signals of weather stations selected in Europe are monofractal. This study reveals that the information obtained in this way are richer than previous works studying long range correlations in meteorological stations. The approach presented here allows to bind the H\\"older exponents with the climate variability. We also establish that such a link does not exist with methods previously carried out.

Deliège, Adrien

2014-01-01

79

Temperature and Precipitation Trends and Variability in Alaska Since 1950  

Microsoft Academic Search

The northern hemisphere has experienced a general warming trend in recent decades that is most pronounced at high latitudes. For Alaska, the mean annual temperature has increased approximately 1.4°C for the most recent climate normal (1971-2000). However, it is important to note that the increase is non-linear and exhibits seasonal and spatial variability. In this investigation, climate records for first-order

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

2002-01-01

80

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

E-print Network

of coordinative optimization control for variable chilled water temperature and variable chilled water flow to obtain better power savings is put forward. According to typical meteorological year data, hourly air conditioning load of whole year for every typical...

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

2006-01-01

81

Effective Temperature and Surface Gravity of Mira Variables  

NASA Astrophysics Data System (ADS)

Synthetic and observed spectra are compared to yield effective temperatures and surface gravities for three Mira variables, R Leo, V CVn, and R CVn as a function of phase. Spectra are synthesized with ATLAS, using model atmospheres obtained from the Kurucz and Indiana University datasets. Experimental data was provided by M.W. Castelaz and E. Messer, and a best fit was determined between the two. Zirconium oxide at 6500 Angstroms was found to be a good indicator of surface gravity. We find a general decrease in Teff and log g as phase increases from 0 to 0.5, which is consistent with observed visual magnitudes.

Piontek, R. A.; Luttermoser, D. G.

1999-09-01

82

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

83

Multilevel analysis of spatial temperature variability in Brno region  

NASA Astrophysics Data System (ADS)

Urban climate is typical with changes in temperature regime compared to rural landscape. This is related to e.g. prevalence of artificial surfaces or production of anthropogenic heat. An Urban Heat Island can be a typical demonstration of urban climate. Temperature variability in urban environment can be studied on different levels using different data sources such as standard meteorological measurements, special-purpose measurements or e.g. thermal satellite imagery. Spatial distribution of land surface temperatures (LST) in Brno and surroundings was modeled using available satellite imagery from Terra ASTER and Landsat 7 ETM+. We present two different methodological approaches that can be used for construction of LST fields. Since Landsat 7 ETM+ offers a single thermal imagery, the first approach uses emissivity maps that must be constructed from land-use categories in advance. Terra ASTER provides five thermal images and both emissivity and LST can be computed directly from them. We compare both methods and provide LST maps for Brno region. These maps are used to describe spatial distribution of LST and to detect areas that are typical with higher LST values. Whereas thermal imagery provide spatially consistent information on surface temperatures, effects of urban environment on air temperatures can be studied with the help of network of special-purpose meteorological stations. Such network has been established in Brno region during 2009. Spatiotemporal changes in air temperatures are described for a set of days with a radiation type of weather. Spatial interpolation methods of air temperatures within urban environment are discussed and compared with results of LST mapping.

Dobrovolný, P.; Brázdil, R.; Krahula, L.

2010-09-01

84

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

85

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

86

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

87

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

88

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

89

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

90

Amplification of surface temperature trends and variability in thetropical atmosphere  

SciTech Connect

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

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

2005-08-11

91

Sea surface temperature variability in the Colombian Basin, Caribbean Sea  

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

92

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

E-print Network

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

Meyers, Steven D.

93

Comparison of temperature variability in observations and sixteen climate model simulations  

NASA Astrophysics Data System (ADS)

Understanding how much, if any, of observed climate changes are anthropogenic depends upon understanding the magnitude and spatial patterns of natural climate variability. We have compared simulated surface air temperature (SAT) variability in 16 coupled ocean-atmosphere-sea ice climate model simulations to observed temperature variability. The majority of the simulations exhibit excessive air temperature variability over land while simulated temperature variability over oceans is generally too low. The ratio of variability over land to over oceans is too high in all the simulations, relative to observations. We have identified several factors which may contribute to the differences in temperature variability. In particular, many of the models use ``bucket'' land surface schemes which produce greater temperature variability over land, due to lower levels of soil moisture, than more realistic land surface schemes produce.

Bell, J.; Duffy, P.; Covey, C.; Sloan, L.

94

Comparison of temperature variability in observations and sixteen climate model simulations  

NASA Astrophysics Data System (ADS)

Understanding how much, if any, of observed climate changes are anthropogenic depends upon understanding the magnitude and spatial patterns of natural climate variability. We have compared simulated surface air temperature (SAT) variability in 16 coupled ocean-atmosphere-sea ice climate model simulations to observed temperature variability. The majority of the simulations exhibit excessive air temperature variability over land while simulated temperature variability over oceans is generally too low. The ratio of variability over land to over oceans is too high in all the simulations, relative to observations. We have identified several factors which may contribute to the differences in temperature variability. In particular, many of the models use ”bucket” land surface schemes which produce greater temperature variability over land, due to lower levels of soil moisture, than more realistic land surface schemes produce.

CMIP Investigators; Bell, J.; Duffy, P.; Covey, C.; Sloan, L.

95

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

96

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

E-print Network

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

Sprintall, Janet

97

Stratospheric temperature trends: impact of ozone variability and the QBO  

NASA Astrophysics Data System (ADS)

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

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

2010-02-01

98

The Use of Equivalent Temperature to Analyse Climate Variability  

Microsoft Academic Search

Equivalent temperature based in the NCEP\\/NCAR reanalysis database has been used as a simultaneous measure of temperature and humidity. Its variations during the 1958-1998 added to the effect of the inclusion of satellite data during the late seventies have been analyzed. An increase of the globally averaged equivalent temperature has been detected, the trend has been considerably greater during the

P. Ribera; D. Gallego; L. Gimeno; J. F. Perez-Campos; R. García-Herrera; E. Hernández; L. de la Torre; R. Nieto; N. Calvo

2004-01-01

99

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

100

Variable-temperature infrared spectra of VO/sub 2/  

SciTech Connect

The infrared spectra of VO/sub 2/ powder in KBr from 1300 to 400 cm/sup -1/ during heating and cooling through the metal-insulator transition are reported. In the high-temperature metallic region, the spectra are nearly featureless, while below the transition temperature well-developed vibrational bands are observed. The spectra at room temperature before and after heating are superimposable, a result consistent with the reversibility of the metal-insulator transition.

Hewston, T.A.; Nadler, M.P.

1987-11-01

101

Middle Pliocene Sea Surface Temperature Variability Harry J. Dowsett1  

E-print Network

, NC 27708 Abstract Estimates of sea surface temperature (SST) based upon foraminifer, diatom, important oceanic fronts in the Southern Ocean were situated significantly closer to the Antarctic continent

102

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...

103

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

104

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

105

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

106

Spatial patterns of intraseasonal variability of chlorophyll and sea surface temperature in the California Current  

E-print Network

Spatial patterns of intraseasonal variability of chlorophyll and sea surface temperature to quantify and map intraseasonal variability of chlorophyll and sea surface temperature (SST. The mode 1 EOFs for both chlorophyll and SST semivariograms indicate a dominant timescale of $60 days

Townsend, David W.

107

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

108

Temporal and spatial variability of surface temperature over Texas  

E-print Network

Surface temperature is one of the most fundamental aspects of the climate system, and its study has been the focus of extensive research in the field of climatology for years. Examination of its temporal and spatial fluctuations can provide...

Moninski, Anthony David

2012-06-07

109

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

110

Ground surface temperatures in Canada: Spatial and temporal variability  

E-print Network

of high frequency noise [Karl et al., 1989] and also because of the large number of energy exchange temperature histories (GSTHs) and surface heat flux histor- ies from geothermal data in Canada [Beltrami et al

Long, Bernard

111

General Characteristics of Temperature and Humidity Variability on Kilimanjaro, Tanzania  

Microsoft Academic Search

Hourly temperature and humidity observations were obtained over 16 months from loggers ranging in elevation from 1890 to 5800 m a.s.l. up the southwestern slope of Kilimanjaro, Tanzania. The vertical gradient in mean air temperature is non-linear, with the treeline weakening the gradient and the snow-ice line enhancing it. On average, moisture availability (both relative humidity and absolute vapor pressure)

W. J. Duane; N. C. Pepin; M. L. Losleben; D. R. Hardy

2008-01-01

112

Simulated and observed variability in ocean temperature and heat content  

PubMed Central

Observations show both a pronounced increase in ocean heat content (OHC) over the second half of the 20th century and substantial OHC variability on interannual-to-decadal time scales. Although climate models are able to simulate overall changes in OHC, they are generally thought to underestimate the amplitude of OHC variability. Using simulations of 20th century climate performed with 13 numerical models, we demonstrate that the apparent discrepancy between modeled and observed variability is largely explained by accounting for changes in observational coverage and instrumentation and by including the effects of volcanic eruptions. Our work does not support the recent claim that the 0- to 700-m layer of the global ocean experienced a substantial OHC decrease over the 2003 to 2005 time period. We show that the 2003–2005 cooling is largely an artifact of a systematic change in the observing system, with the deployment of Argo floats reducing a warm bias in the original observing system. PMID:17578928

AchutaRao, K. M.; Ishii, M.; Santer, B. D.; Gleckler, P. J.; Taylor, K. E.; Barnett, T. P.; Pierce, D. W.; Stouffer, R. J.; Wigley, T. M. L.

2007-01-01

113

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

114

Historical Temperature Variability Affects Coral Response to Heat Stress  

Microsoft Academic Search

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

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

2012-01-01

115

Models of Solar Irradiance Variability and the Instrumental Temperature Record  

NASA Technical Reports Server (NTRS)

The effects of decade-to-century (Dec-Cen) variations in total solar irradiance (TSI) on global mean surface temperature Ts during the pre-Pinatubo instrumental era (1854-1991) are studied by using two different proxies for TSI and a simplified version of the IPCC climate model.

Marcus, S. L.; Ghil, M.; Ide, K.

1998-01-01

116

TEMPORAL AND SPATIAL VARIABILITY OF TEMPERATURE IN TWO COASTAL LAGOONS  

Microsoft Academic Search

With in situ continuous recording thermographs, year-long surface-temperature time series were gener- ated at four points in San Quintin Bay and at three points in Estero de Punta Banda. During spring and summer, upwelling events were clearly detected at the mouth of San Quintin Bay. Upwelled waters propa- gate throughout San Quintin Bay by tidal currents. In both coastal lagoons

JOSUE ALVAREZ-BORREGO; SAUL ALVAREZ-BORREGO

1982-01-01

117

Diurnal variability in currents and temperature on the continental shelf between central and southern  

E-print Network

Diurnal variability in currents and temperature on the continental shelf between central and the temperature and current response on the continental shelf of California between Port San Luis and Port Hueneme and temperature on the continental shelf between central and southern California, J. Geophys. Res., 110, C03024

Winant, Clinton D.

118

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

119

Complexation of Plutonium (IV) with Fluoride at Variable Temperatures  

SciTech Connect

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

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

2010-02-02

120

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

121

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

PubMed Central

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

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

2007-01-01

122

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

123

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

124

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

125

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

E-print Network

The Wind-Evaporation-Sea Surface Temperature (WES) feedback is believedto play an important role in the tropics, where climate variability is governed byatmosphere-ocean coupled interactions. This dissertation reports on studies to distinctlyisolate...

Mahajan, Salil

2009-05-15

126

Recent variability and trends of Antarctic near-surface temperature Andrew J. Monaghan,1  

E-print Network

Recent variability and trends of Antarctic near-surface temperature Andrew J. Monaghan,1 David H in the most recent decades is corroborated by Chapman and Walsh [2007]; they perform a gridded objective

Howat, Ian M.

127

Beyond average: an experimental test of temperature variability on the population dynamics of Tribolium confusum  

Microsoft Academic Search

The relationship between ectotherm ecology and climatic conditions has been mainly evaluated in terms of average conditions.\\u000a Average temperature is the more common climatic variable used in physiological and population studies, and its effect on individual\\u000a and population-level processes is well understood. However, the intrinsic variability of thermal conditions calls attention\\u000a to the potential effects that this variability could have

Sergio A. Estay; Sabrina Clavijo-Baquet; Mauricio Lima; Francisco Bozinovic

2011-01-01

128

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

Microsoft Academic Search

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

S. J. GOETZ

1997-01-01

129

Interannual-to-multidecadal climate variability and its relationship to global sea surface temperatures  

E-print Network

) and the multi-decadal North Atlantic Oscillation (NAO). The variable of greatest interest is sea surfaceInterannual-to-multidecadal climate variability and its relationship to global sea surface temperatures David B. Enfield 1 and Alberto M. Mestas-Nuñez 2 1 NOAA Atlantic Oceanographic and Meteorological

130

ASSOCIATIONS OF DECADAL TO MULTIDECADAL SEA-SURFACE TEMPERATURE VARIABILITY WITH UPPER COLORADO RIVER FLOW1  

E-print Network

reflects variability associated with the Atlantic Multidecadal Oscillation and the second RPC (RPC2, with critical implications for UCRB water resource management. (KEY TERMS: Colorado River; Atlantic MultidecadalASSOCIATIONS OF DECADAL TO MULTIDECADAL SEA-SURFACE TEMPERATURE VARIABILITY WITH UPPER COLORADO

131

Modes of mesoscale sea surface height and temperature variability in the East Australian Current  

Microsoft Academic Search

Mesoscale variability where the East Australian Current (EAC) separates from the coast is studied using sea surface temperature and surface velocity streamfunction observed by satellite and a regional numerical model. The mean circulation simulated by the model (the Regional Ocean Modeling System (ROMS)) is compared to a high-resolution regional climatology, and the realism of the simulated mesoscale variability is tested

John L. Wilkin; Weifeng G. Zhang

2007-01-01

132

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

Microsoft Academic Search

Variability and predictability of European summer drought conditions during observational period is investigated. The dominat patterns of European drought and their associated large-scale climatic anomalies are identified through canonical correlation analysis (CCA) of the field of self calibrating Palmer Drought Severity Index (PDSI) and global sea surface temperature (SST) anomalies. At interannual time scales we identified patterns of drought variability

Monica Ionita; Gerrit Lohmann; Norel Rimbu; Silvia Chelcea

2010-01-01

133

Interannual Variability of Monsoon Precipitation and Local Subcloud Equivalent Potential Temperature  

E-print Network

Interannual Variability of Monsoon Precipitation and Local Subcloud Equivalent Potential The interannual variability of monsoon precipitation is described in the context of a convective quasi temperature (ueb) local to six monsoon regions. This approach provides a single near-surface thermody

134

Evidence for Large Temperature Fluctuations in Quasar Accretion Disks from Spectral Variability  

NASA Astrophysics Data System (ADS)

The well-known bluer-when-brighter trend observed in quasar variability is a signature of the complex processes in the accretion disk and can be a probe of the quasar variability mechanism. Using a sample of 604 variable quasars with repeat spectra in the Sloan Digital Sky Survey-I/II (SDSS), we construct difference spectra to investigate the physical causes of this bluer-when-brighter trend. The continuum of our composite difference spectrum is well fit by a power law, with a spectral index in excellent agreement with previous results. We measure the spectral variability relative to the underlying spectra of the quasars, which is independent of any extinction, and compare to model predictions. We show that our SDSS spectral variability results cannot be produced by global accretion rate fluctuations in a thin disk alone. However, we find that a simple model of an inhomogeneous disk with localized temperature fluctuations will produce power-law spectral variability over optical wavelengths. We show that the inhomogeneous disk will provide good fits to our observed spectral variability if the disk has large temperature fluctuations in many independently varying zones, in excellent agreement with independent constraints from quasar microlensing disk sizes, their strong UV spectral continuum, and single-band variability amplitudes. Our results provide an independent constraint on quasar variability models and add to the mounting evidence that quasar accretion disks have large localized temperature fluctuations.

Ruan, John J.; Anderson, Scott F.; Dexter, Jason; Agol, Eric

2014-03-01

135

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

136

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

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

A mass-selective variable-temperature drift tube ion mobility-mass spectrometer for temperature dependent ion mobility studies.  

PubMed

A hybrid ion mobility-mass spectrometer (IM-MS) incorporating a variable-temperature (80-400 K) drift tube is presented. The instrument utilizes an electron ionization (EI) source for fundamental small molecule studies. Ions are transferred to the IM-MS analyzer stages through a quadrupole, which can operate in either broad transmission or mass-selective mode. Ion beam modulation for the ion mobility experiment is accomplished by an electronic shutter gate. The variable-temperature ion mobility spectrometer consists of a 30.2 cm uniform field drift tube enclosed within a thermal envelope. Subambient temperatures down to 80 K are achievable through cryogenic cooling with liquid nitrogen, while elevated temperatures can be accessed through resistive heating of the envelope. Mobility separated ions are mass analyzed by an orthogonal time-of-flight (TOF) mass spectrometer. This report describes the technological considerations for operating the instrument at variable temperature, and preliminary results are presented for IM-MS analysis of several small mass ions. Specifically, mobility separations of benzene fragment ions generated by EI are used to illustrate significantly improved (greater than 50%) ion mobility resolution at low temperatures resulting from decreased diffusional broadening. Preliminary results on the separation of long-lived electronic states of Ti(+) formed by EI of TiCl(4) and hydration reactions of Ti(+) with residual water are presented. PMID:21953095

May, Jody C; Russell, David H

2011-07-01

139

Preparation of Cold Brew Tea by Explosion Puffing Drying at Variable Temperature and Pressure  

Microsoft Academic Search

Cold brew tea was prepared using explosion puffing drying at variable temperature and pressure. The influences of moisture content of predried tea leaves, freezing pretreatment times at ?18°C, and puffing temperature on water extracts content of cold brew tea were studied according to the orthogonal experiments of processing of cold brew tea based on single factors. The biochemistry ingredients of

Xin-Yi He; Jin-Fu Liu; Zong-Hai Huang

2011-01-01

140

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

E-print Network

columnar water vapor is less than $7 mm. These effects are removed empirically. For Argo data collectedDiurnal variability of upper ocean temperatures from microwave satellite measurements and Argo by pairing Argo temperature profiles with geographically colocated Advanced Microwave Scanning Radiometer

Gille, Sarah T.

141

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

142

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

143

Century-scale solar variability and Alaskan temperature change over the past millennium  

E-print Network

. Wiles,1 Rosanne D. D'Arrigo,2 Ricardo Villalba,3 Parker E. Calkin,4 and David J. Barclay5 Received 22. Barclay (2004), Century-scale solar variability and Alaskan temperature change over the past millennium to be primarily a record of summer temperature change [Barclay et al., 1999; Davi et al., 2003]. Well

Barclay, David J.

144

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

145

Determination of reaction kinetic parameters from variable temperature DSC or DTA  

Microsoft Academic Search

An equation is derived for evaluating the kinetic parameters of a transformation from variable temperature DSC or DTA, taking account of the variation in the reaction rate constant with time and temperature. Kinetic parameters for the crystallization of a ZrF4-BaF2-LaF3 glass are calculated using this equation.

N. P. Bansal; R. H. Doremus

1984-01-01

146

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

NASA Astrophysics Data System (ADS)

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

Way, Robert G.; Viau, Andre E.

2014-08-01

147

Atlantic Sea Surface Temperature Variability and its Relationship to Overlying Air Temperature, Sea Level Pressure, and 500 MB Teleconnections  

Microsoft Academic Search

Six regions of Atlantic ocean variability were identified with a rotated principal component analysis of normalized anomalies of monthly sea surface temperature for 1946-1988. The factor patterns were named: (1) Tropics, (2) Mid Atlantic, (3) Eastern Atlantic, (4) North Atlantic, (5) Southeast United States Coast (which included a smaller area around the British Isles), and (6) Caribbean to North Africa.

Mary Louise Marshall

1994-01-01

148

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

SciTech Connect

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

Rao, Linfeng; Tian, Guoxin

2008-12-10

149

Long-term trends and interannual variability of temperature in Drake Passage  

Microsoft Academic Search

Temperature data collected over the last 36years (1969–2004) in Drake Passage are used to examine interannual temperature variation and long-term trends in the upper ocean. To reduce the effect of variation from different sampling locations and temporal variability introduced by meridional shifts in the Polar Front (PF), the data were divided into two sub-regions north (?3800 temperature profiles) and south

Janet Sprintall

2008-01-01

150

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

151

An interaction network perspective on the relation between patterns of sea surface temperature variability and global mean surface temperature  

NASA Astrophysics Data System (ADS)

On interannual- to multidecadal timescales variability in sea surface temperature appears to be organized in large-scale spatiotemporal patterns. In this paper, we investigate these patterns by studying the community structure of interaction networks constructed from sea surface temperature observations. Much of the community structure can be interpreted using known dominant patterns of variability, such as the El Niño/Southern Oscillation and the Atlantic Multidecadal Oscillation. The community detection method allows us to bypass some shortcomings of Empirical Orthogonal Function analysis or composite analysis and can provide additional information with respect to these classical analysis tools. In addition, the study of the relationship between the communities and indices of global surface temperature shows that, while El Niño-Southern Oscillation is most dominant on interannual timescales, the Indian West Pacific and North Atlantic may also play a key role on decadal timescales. Finally, we show that the comparison of the community structure from simulations and observations can help detect model biases.

Tantet, A.; Dijkstra, H. A.

2014-01-01

152

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

153

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

154

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

PubMed

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?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. PMID:24599494

Okada, Masahiro; Kakehashi, Masayuki

2014-11-01

155

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

156

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

Microsoft Academic Search

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

Gregory J. McCabe; Julio L. Betancourt; Stephen T. Gray; Michael A. Palecki; Hugo G. Hidalgo

2008-01-01

157

Investigation into wave properties of the atlantic surface temperature spatial variability on interannual scales  

NASA Astrophysics Data System (ADS)

The results of investigations into the spatial variability of the Atlantic Ocean surface temperature field on interannual scales are presented. The analysis is based on monthly mean satellite data of the AVHRR Pathfinder Data JPL NOAA/NASA over 1985-2001. Specific features of the structure of the sea surface temperature (SST) fields averaged over 17 years, as well as fields of the gradient and variance of the SST time series, are described for each node of the data grid. It is shown with the use of the rhythmodynamic approach that spatial heat waves exist in the interannual variability of the SST field in two directions: zonal and meridional.

Eremeev, V. N.; Zhukov, A. N.; Sizov, A. A.

2012-12-01

158

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

NASA Astrophysics Data System (ADS)

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

2014-04-01

159

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

NASA Astrophysics Data System (ADS)

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

160

A variable-temperature surrogate mother for studying attachment in infant monkeys  

Microsoft Academic Search

A variable temperature surrogate mother for use with infant monkeys is described. The apparatus is designed to facilitate\\u000a manipulation of the infant-surrogate attachment bond. Data showing significant behavioral changes in ventral contact and locomotion\\u000a as a function of depressed surrogate temperature are presented. The value of this technique in the production of psyehopathology\\u000a is indicated by a dramatic and progressive

C. M. Baysinger; P. E. Plubell; H. F. Harlow

1973-01-01

161

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

Microsoft Academic Search

Interannual to decadal variability of European summer drought and its relationship with global sea surface temperature (SST)\\u000a is investigated using the newly developed self calibrated Palmer drought severity index (scPDSI) and global sea surface temperature\\u000a (SST) field for the period 1901–2002. A European drought severity index defined as the average of scPDSI over entire Europe\\u000a shows quasiperiodic variations in the

M. Ionita; G. Lohmann; N. Rimbu; S. Chelcea; M. Dima

2011-01-01

162

North Pacific and North Atlantic sea-surface temperature variability during the Holocene  

Microsoft Academic Search

Holocene climate variability is investigated in the North Pacific and North Atlantic realms, using alkenone-derived sea-surface temperature (SST) records as well as a millennial scale simulation with a coupled atmosphere-ocean general circulation model (AOGCM). The alkenone SST data indicate a temperature increase over almost the entire North Pacific from 7 cal kyr BP to the present. A dipole pattern with

Jung-Hyun Kima; Stephan J. Lorenzb; Stefan Schoutene; Ralph R. Schneiderg; Stilleweg Meeresgeologie

163

Influence of Arctic Oscillation towards the Northern Hemisphere Surface Temperature Variability under the Global Warming Scenario  

Microsoft Academic Search

Future projection of the Arctic Oscillation (AO) signature and its significance towards the northern hemispheric surface temperature trend have been examined using 20 state-of-the-art Atmosphere-Ocean General Circulation Model (AOGCM) outputs forced under the IPCC SRES-A1B and 20C3M emission scenario. Models are mostly successful in simulating the observed AO structure and the corresponding surface temperature variability. It is found that while

Masatake E. HORI; Daisuke NOHARA; Hiroshi L. TANAKA

2007-01-01

164

Temperature variability in X-ray bright points observed with Hinode/XRT  

NASA Astrophysics Data System (ADS)

Aims: We investigate the variability in temperature as a function of time among a sample of coronal X-ray bright points (XBPs). Methods: We analysed a 7-h (17:00-24:00 UT) long time sequence of soft X-ray images observed almost simultaneously in two filters (Ti_poly and Al_mesh) on April 14, 2007 with X-ray telescope (XRT) onboard the Hinode mission. We identified and selected 14 XBPs for a detailed analysis. The light curves of XBPs were derived using the SolarSoft library in IDL. The temperature of XBPs was determined using the calibrated temperature response curves of the two filters by means of the intensity ratio method. Results: We find that the XBPs show a high variability in their temperature and that the average temperature ranges from 1.1 MK to 3.4 MK. The variations in temperature are often correlated with changes in average X-ray emission. It is evident from the results of time series that the XBP heating rate can be highly variable on short timescales, suggesting that it has a reconnection origin.

Kariyappa, R.; Deluca, E. E.; Saar, S. H.; Golub, L.; Damé, L.; Pevtsov, A. A.; Varghese, B. A.

2011-02-01

165

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

E-print Network

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

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

166

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

USGS Publications Warehouse

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

Iacobellis, Sam F.; Cayan, Daniel R.

2013-01-01

167

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

PubMed

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

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

2011-05-01

168

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

169

A flexible variable conductance heat pipe design for temperature control of spacecraft equipment  

Microsoft Academic Search

The paper describes a variable conductance heat pipe design with a flexible joint. The heat pipe is developed for temperature control of high power electronics using a deployable space radiator. The evaporator section of the heat pipe is attached to the baseplate of the electronics. The condenser section of the heat pipe and the reservoir of noncondensible gas are attached

Han Hwangbo; T. E. Joost

1988-01-01

170

Higher-order sensing using QCM sensor array and preconcentrator with variable temperature  

Microsoft Academic Search

Proposed the higher-order sensing method using preconcentrator with variable temperature in combination with the QCM sensor array to extract features of the samples. The rough separation among the compounds along the time axis enhanced the discrimination capability of the sensor array system. The results of the second-order sensing such as the images of the sensor responses and the loci on

T. Nakamoto; K. Sukegawa; E. Sumitomo

2002-01-01

171

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

E-print Network

variability of the Atlantic Multidecadal Oscillation (AMO) and the Atlantic Meridional Overturning CirculationMultidecadal 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

172

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

173

Florida Current surface temperature and salinity variability during the last millennium  

Microsoft Academic Search

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

David C. Lund; William Curry

2006-01-01

174

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

175

Impact of tropical convective activity on monthly temperature variability during nonmonsoon season in the Nepal Himalayas  

Microsoft Academic Search

Surface air temperature, observed in the eastern Nepal Himalayas, showed large intraseasonal and year-to-year variability during the nonmonsoon season. A significant negative correlation was found in the monthly outgoing longwave radiation (OLR) between the area over the Himalayas and tropical areas between 80 and 150°E, which was confirmed by in situ observation data. The correlation was stronger in the months

Kenichi Ueno; Raju Aryal

2008-01-01

176

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

E-print Network

MONTHLY TEMPERATURE, SALINITY AND TRANSPORT VARIABILITY OF THE BERING STRAIT THROUGHFLOW Rebecca A Street, Seattle, WA98105, USA, woodgate@apl.washington.edu ABSTRACT The Bering Strait throughflow the magnitude of the Pacific-Arctic pressure-head forcing of the Bering Strait throughflow. INDEX TERMS: 4207

Washington at Seattle, University of

177

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

178

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

USGS Publications Warehouse

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

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

1990-01-01

179

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

180

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

SciTech Connect

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

Wallace, J.M.; Zhang, Yuan

1997-11-01

181

Temperature, salinity, and density variability in the central Middle Atlantic Bight  

NASA Astrophysics Data System (ADS)

Four years of sustained glider observations are used to compute the seasonal cycle of hydrographic fields in the central Middle Atlantic Bight (MAB). Results reveal a large phase lag in near bottom temperatures, with peak values occurring in September at the inner shelf, in October at the mid shelf, and in November at the outer shelf. Unlike the northern MAB, the seasonal cycle explains over 70% of the near-surface salinity variability. At the inner shelf and offshore near the bottom, however, most of the variance is due to pulses in river discharge and to shifts in the position of the shelfbreak front. Cross-shelf density gradients inshore of the 60-m isobath are dominated by salinity during winter and spring, with temperature contributing significantly from August to October. This is because bottom waters near the coast are warm due to the deepening of the thermocline during fall, but offshore waters are still influenced by the cold pool. The vertical stratification seasonal variability is also large. Early in the year, stratification is small and entirely due to salinity. By May, salinity still dominates vertical gradients near the coast, but temperature and salinity contribute equally to the density stratification offshore. During summer, stratification is dominated by temperature. Temperature interannual variability was small during the sampling period, but surface salinity was anomalously low by 1.2 psu in summer 2006. The anomaly was due to larger than average discharge from the Hudson River in early summer during a period of strong upwelling favorable winds.

Castelao, Renato; Glenn, Scott; Schofield, Oscar

2010-10-01

182

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

183

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

PubMed Central

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

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

2013-01-01

184

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

USGS Publications Warehouse

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

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

2003-01-01

185

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

PubMed

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

Plaut, G; Ghil, M; Vautard, R

1995-05-01

186

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

187

Evidence for Large Temperature Fluctuations in Quasar Accretion Disks From Spectral Variability  

E-print Network

The well-known bluer-when-brighter trend observed in quasar variability is a signature of the complex processes in the accretion disk, and can be a probe of the quasar variability mechanism. Using a sample of 604 variable quasars with repeat spectra in SDSS-I/II, we construct difference spectra to investigate the physical causes of this bluer-when-brighter trend. The continuum of our composite difference spectrum is well-fit by a power-law, with a spectral index in excellent agreement with previous results. We measure the spectral variability relative to the underlying spectra of the quasars, which is independent of any extinction, and compare to model predictions. We show that our SDSS spectral variability results cannot be produced by global accretion rate fluctuations in a thin disk alone. However, we find that a simple model of a inhomogeneous disk with localized temperature fluctuations will produce power-law spectral variability over optical wavelengths. We show that the inhomogeneous disk will provide ...

Ruan, John J; Dexter, Jason; Agol, Eric

2014-01-01

188

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

USGS Publications Warehouse

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

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

2013-01-01

189

The stochastic properties of high daily maximum temperatures applying crossing theory to modeling high-temperature event variables  

NASA Astrophysics Data System (ADS)

The statistical properties of the excursions of maximum daily temperatures above various critical thresholds of interest are analyzed with a view to developing models of heat wave events using more than 100 years of record from meteorological stations in Lake City, DeFuniak Springs, Avon Park, and Fort Myers, Florida. These stochastic variables include; event density (number of such events per unit time), duration, timing, and peak values over the threshold. The theoretical basis for the modeling is found in Crossing Theory. The methodology has the flexibility to extrapolate to such levels while also having the advantage of being able to be applied to spatially differentiated data to determine risks associated with high-temperature events during any time period or at any location of interest.

Keellings, David; Waylen, Peter

2012-05-01

190

Energy conservation evaluation of two variable interval time/temperature heat pump defrost control strategies  

SciTech Connect

The variable interval time/temperature (VITT) defrost control systems monitor outside air dry-bulb temperature and use the measured data to alter the interval between defrost. However, for any outdoor temperature, the VITT systems, defrost at constant intervals of time. Analyses of the VITT-A A and VITT-B strategies have been performed for the Department of Energy to assess the energy-saving potential of VITT defrost control sytems as compared to demand and fixed-interval time/temperature (FITT) defrost control systems. VITT defrost control strategies result in seasonal performance that is more energy efficient that that of FITT strategies and less energy efficient than that of demand defrost controls. 7 refs.

Rettberg, R.J.

1981-01-01

191

Statistics of Air Temperature Spatial Variability in the Atmospheric Surface Layer  

NASA Astrophysics Data System (ADS)

Surface-layer convection is investigated by analyzing multi-point measurements of temperature and velocity fluctuations at different sets of spatial points.The visual analysis of temperature and velocity fluctuations measured by sensors mounted on a mast of 36-m height clearly reveals the presence of large-scale convective cells (known as ramp structures) making large contributions to the heat transfer from the ground to lower atmosphere. The vertical temperature variability is described with the aid of empirical orthogonal functions derived from temperature covariance matrices for the heights of 1, 2, 5, 10, 18 and 36 m. Temporal-spatial correlation functions obtained allow estimates of a characteristic velocity scale, which may be interpreted as the downwind velocity of ramp structures.

Koprov, B. M.; Zubkovsky, S. L.; Koprov, V. M.; et al.

192

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

193

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

NASA Astrophysics Data System (ADS)

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

Christiansen, Bo

2010-05-01

194

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

195

Impact of tropical convective activity on monthly temperature variability during nonmonsoon season in the Nepal Himalayas  

NASA Astrophysics Data System (ADS)

Surface air temperature, observed in the eastern Nepal Himalayas, showed large intraseasonal and year-to-year variability during the nonmonsoon season. A significant negative correlation was found in the monthly outgoing longwave radiation (OLR) between the area over the Himalayas and tropical areas between 80 and 150°E, which was confirmed by in situ observation data. The correlation was stronger in the months of December, March, and April with different correlative areas in the tropics. From comparison of data observed over 10 years with OLR and global precipitation data, the variability of monthly local surface air temperature in winter was primarily attributed to the indirect effect of convective activities in the tropics that caused a variation in the precipitation/snow cover condition at high elevations.

Ueno, Kenichi; Aryal, Raju

2008-09-01

196

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

197

Modality of semiannual to multidecadal oscillations in global sea surface temperature variability  

Microsoft Academic Search

Repeating the history of study on El Niño-Southern Oscillation (ENSO) in the 1980s, interdecadal oscillation (IDO) in climate variability is currently an area of active research and debate, following the recognition of its emerging significance in nature and science. In this work, a two-dimensional propagating modal extraction technique is applied to a reconstructed global monthly sea surface temperature (SST) data

Ge Chen; Baomin Shao; Yong Han; Jun Ma; Bertrand Chapron

2010-01-01

198

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

199

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

200

Sr\\/Ca as a Potential Proxy of Subsurface Temperature Variability in C. secundum  

Microsoft Academic Search

There is increasing interest in the development of proxy records of oceanographic variability from intermediate and deep-water environments using deep-sea corals. Recent work has focused on isotopic and elemental ratios as proxies for temperature with limited success. Here we explore the potential uses of Mg\\/Ca and Sr\\/Ca in the same Corallium secundum sample using LA-ICP-MS. C. secundum samples where collected

E. Roark; S. J. Fallon; T. P. Guilderson; R. B. Dunbar; M. T. McCulloch

2009-01-01

201

Pronounced interannual variability in tropical South Pacific temperatures during Heinrich Stadial 1.  

PubMed

The early last glacial termination was characterized by intense North Atlantic cooling and weak overturning circulation. This interval between ~18,000 and 14,600 years ago, known as Heinrich Stadial 1, was accompanied by a disruption of global climate and has been suggested as a key factor for the termination. However, the response of interannual climate variability in the tropical Pacific (El Niño-Southern Oscillation) to Heinrich Stadial 1 is poorly understood. Here we use Sr/Ca in a fossil Tahiti coral to reconstruct tropical South Pacific sea surface temperature around 15,000 years ago at monthly resolution. Unlike today, interannual South Pacific sea surface temperature variability at typical El Niño-Southern Oscillation periods was pronounced at Tahiti. Our results indicate that the El Niño-Southern Oscillation was active during Heinrich Stadial 1, consistent with climate model simulations of enhanced El Niño-Southern Oscillation variability at that time. Furthermore, a greater El Niño-Southern Oscillation influence in the South Pacific during Heinrich Stadial 1 is suggested, resulting from a southward expansion or shift of El Niño-Southern Oscillation sea surface temperature anomalies. PMID:22828625

Felis, Thomas; Merkel, Ute; Asami, Ryuji; Deschamps, Pierre; Hathorne, Ed C; Kölling, Martin; Bard, Edouard; Cabioch, Guy; Durand, Nicolas; Prange, Matthias; Schulz, Michael; Cahyarini, Sri Yudawati; Pfeiffer, Miriam

2012-01-01

202

Decadal North Pacific sea surface temperature variability and the associated global climate anomalies in a coupled general circulation model  

Microsoft Academic Search

We explore the characteristics of decadal North Pacific sea surface temperature (SST) variability along with its relationship to global climate variations based on the analysis of a long-term coupled model simulation (300 years). Two key regions of North Pacific decadal variability, i.e., the western North Pacific (WNP) and central North Pacific (CNP) SST variability, are defined. While the global atmospheric

Sang-Wook Yeh; Ben P. Kirtman

2004-01-01

203

Indian Ocean sea surface temperature variability and change since 1960s: forcing and process  

NASA Astrophysics Data System (ADS)

Indian Ocean sea surface temperature (SST) variability and change since 1960s are investigated using global coupled models,the Community Climate System Model version 3 (CCSM3) and parallel climate model (PCM). Results from the CCSM3 and a series of PCM experiments are analyzed in order to understand the roles played by internal variability, human-induced warming, and external forcing in causing the SST variations. To consolidate the model results, the simple Ocean model Data Assimilation (SODA) products are also analyzed. The results suggest that the SST in both the south and north Indian Ocean (IO) has an increasing trend. Overlying on this trend is decadal variability. Consistent with previous studies, the warming trend results mainly from the human-induced increased green house gases, which increase downward longwave fluxes. Interestingly, warming of the upper tropical and subtropical basins is accomanied by cooling in higher-latitudes in the Antarctic Circumpolar Current (ACC) region, which results from the reduced southward heat transports by weakened the subtropical cells (STCs). This colder, ACC water can enter the IO via deep layers in the south and then shoals upward to the thermocline layer in the tropical Indian Ocean, causing a distinct vertical structrure: with warming in the near surface and below the thermocline and cooling in the thermocline. The SST decadal variability, however, is caused primarily by external forcing, due to a combined effect of surface heat flux and lateral heat transport. Internal variability of the coupled system also plays a role.

Han, W.; Meehl, G. A.; Hu, A.

2005-12-01

204

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

205

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

NASA Astrophysics Data System (ADS)

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

Franquist, Eric S.

206

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

207

Rare-earth doped solid-state phosphor with temperature-induced variable chromaticity  

NASA Astrophysics Data System (ADS)

A temperature induced variable chromaticity phosphor based upon a rare-earth multi-doped solid-state frequency upconverter is presented. The phosphors are composed of ytterbium-sensitized multiple doped(Tm, Er, Ho) lead-cadmium fluorogermanate glass samples excited by a laser source around 1064 nm. The temperature induced color variation exploits the heat enhanced effective absorption cross-section of the ytterbium sensitizer under multiphonon-assisted anti-Stokes excitation. The temperature enhancement of the energy-transfer mechanism between the sensitizer and the appropriate active light emitter ion allows the selective intensity control of the RGB emission wavelengths due to different upconversion excitation routes. The suitable combination of rare-earth active ions yielded the generation of variable chromaticity light with CIE-1931 coordinates changing from CIE-X=0.283;Y=0.288 at 20°C to CIE-X= 0.349;Y=0.412 at 190 °C, and CIE-X=0.285;Y=0.361 at 25°C to CIE-X=0.367;Y=0.434 at 180°C in Yb3+/Tm3+/Ho3+ and Yb3+/Tm3+/Er3+ multidoped samples, respectively. The viability of producing a low cost solid-state changeable visible color remote distributed temperature indicator in the 25°C - 300°C range is also discussed.

Gouveia-Neto, Artur S.; Bueno, Luciano A.; Nascimento, Raphael; Silva, Elias A.; Costa, Ernande B.

2009-02-01

208

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

209

The temperature size rule in arthropods: independent of macro-environmental variables but size dependent.  

PubMed

Temperature is a key factor that affects the rates of growth and development in animals, which ultimately determine body size. Although not universal, a widely documented and poorly understood pattern is the inverse relationship between the temperature at which an ectothermic animal is reared and its body size (temperature size rule [TSR]). The proximate and ultimate mechanisms for the TSR remain unclear. To explore possible explanations for the TSR, we tested for correlations between the magnitude/direction of the TSR and latitude, temperature, elevation, habitat, availability of oxygen, capacity for flight, and taxonomic grouping in 98 species/populations of arthropods. The magnitude and direction of the TSR was not correlated with any of the macro-environmental variables we examined, supporting the generality of the TSR. However, body size affected the magnitude and direction of the TSR, with smaller arthropods more likely to demonstrate a classic TSR. Considerable variation among species exists in the TSR, suggesting either strong interactions with nutrition, or selection based on microclimatic or seasonal variation not captured in classic macro-environmental variables. PMID:23784699

Klok, C Jaco; Harrison, Jon F

2013-10-01

210

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

211

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

212

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

213

The influence of temperature and salinity variability on the upper ocean density and mixed layer  

NASA Astrophysics Data System (ADS)

The relative influence of both temperature and salinity on the mixed layer depth (MLD) is evaluated using a relationship of binned regressions of MLD on vertical density compensation and isothermal layer depth (ILD) from a global set of in situ profile observations. Our approach is inspired by the observations of the difference between the MLD and the sonic layer depth (SLD) that evolve seasonally around the global ocean. In this article, we hypothesize that vertical density compensation governs SLD-MLD differences and can be used for mapping the relative influence of temperature and salinity on upper ocean structure. The Turner angle, computed between the surface and 200 m (bulk Turner angle, BTA), serves as a measure of vertical density compensation that quantifies times and areas where either temperature or salinity is destabilizing. For temperature destabilization the ocean exhibits cool/fresh overlying hot/salty water. For salinity destabilization the ocean exhibits hot/salty overlying cool/fresh water. These two classes of density compensation have seasonal variability with different geographical characteristics. Profiles with salinity controlled stable density and destabilizing temperature gradient are found most often at high latitudes. Profiles with temperature controlled stable density and destabilizing salinity gradient are found in the tropics and subtropics of all oceans. Results indicate that about half of the ocean has vertical density compensation that is a necessary condition for SLD-MLD differences. While density compensation is necessary, it is not a sufficient condition for predicting the dependence of MLD on BTA. Density compensation is the dominant factor in MLD variability in heavy river input and subduction regions that cover only ~14% of the ocean.

Helber, R. W.; Richman, J. G.; Barron, C. N.

2010-08-01

214

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

215

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

216

Thermospheric Variability Paul Withers and Anthony Lollo  

E-print Network

with empirical measurements of thermospheric variability #12;Aerobraking accelerometers MGS, ODY, MRO sampled, longitude, LST, altitude (everything but day-to-day) Occurs for aerobraking when period x N = sol Numbers of solar storms at Mars during aerobraking (MGS ER, others) Responses not well- known, may be small

Withers, Paul

217

Ambient Temperature, Air Pollution, and Heart Rate Variability in an Aging Population  

PubMed Central

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

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

2011-01-01

218

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

PubMed

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

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

2011-05-01

219

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

220

NAO implicated as a predictor of Northern Hemisphere mean temperature multidecadal variability  

NASA Astrophysics Data System (ADS)

twentieth century Northern Hemisphere mean surface temperature (NHT) is characterized by a multidecadal warming-cooling-warming pattern followed by a flat trend since about 2000 (recent warming hiatus). Here we demonstrate that the North Atlantic Oscillation (NAO) is implicated as a useful predictor of NHT multidecadal variability. Observational analysis shows that the NAO leads both the detrended NHT and oceanic Atlantic Multidecadal Oscillation (AMO) by 15-20 years. Theoretical analysis illuminates that the NAO precedes NHT multidecadal variability through its delayed effect on the AMO due to the large thermal inertia associated with slow oceanic processes. An NAO-based linear model is therefore established to predict the NHT, which gives an excellent hindcast for NHT in 1971-2011 with the recent flat trend well predicted. NHT in 2012-2027 is predicted to fall slightly over the next decades, due to the recent NAO decadal weakening that temporarily offsets the anthropogenically induced warming.

Li, Jianping; Sun, Cheng; Jin, Fei-Fei

2013-10-01

221

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

SciTech Connect

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

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

2009-01-01

222

Interannual and interdecadal variability in 335 years of central England temperatures  

SciTech Connect

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

Plaut, G. [Institut Non-Lineaire de Nice, Valbonne (France); Ghil, M. [Univ. of California, Los Angeles, CA (United States); Vautard, R. [Ecole Normale Superieure, Paris (France)

1995-05-05

223

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

NASA Astrophysics Data System (ADS)

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

224

Temporal variability of temperature-nitrate relationship in a coastal region  

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

225

Variability of superconducting transition temperatures of Ag-clad Bi(2223) tapes  

SciTech Connect

The zero-field intersample variability of the superconducting transition temperature was measured for two commercially supplied Ag-clad Bi[sub 2]Sr[sub 2]Ca[sub 2]Cu[sub 3]O[sub x] (Bi(2223)) 37 filament tapes, one 103 m and the second 193 m long. The resistivity of six 30 cm long pieces of each tape was measured with increasing and decreasing temperature. Hysteresis and time-dependent effects were observed. For the 103 m tape, upon cooling, the resistivity deviates from the conventional behavior at (114.3.3.2) K and complete superconductivity is achieved at (105.1.3.9) K. With increasing temperature, deviation from superconductivity starts at (112.5.4.6) K and superconductivity is completely gone at (121.8.3.1) K. The corresponding temperatures for the 193 m tape are (113.4.4.9), (108.6.3.6), (108.9.7.4) and (118.1.7.4) K. For one sample of the 193 m tape, the corresponding temperatures are (107.9.3.1), (102.5.5.9), (100.8.4.3) and (112.0.3.3) K. The anomalously broad foot structure in the zero field resistive transition previously seen by Zhao et al. in single crystals of Bi[sub 2]Sr[sub 2]CaCu[sub 2]O[sub x] (Bi(2212)) was observed here.

Mayo, B. de (State Univ. of West Georgia, Carrollton, GA (United States). Dept. of Mathematics and Physics)

1998-12-20

226

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

227

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

228

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

Microsoft Academic Search

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

Deliang Chen; Cecilia Hellström

1999-01-01

229

Chem. Rev. 1990, 90, 439-457 439 Probing Organic Glasses at Low Temperature with Variable Time Scale  

E-print Network

Chem. Rev. 1990, 90, 439-457 439 Probing Organic Glasses at Low Temperature with Variable Time a crystal, a glass is not in thermodynamic equilibrium. At low temperature, the equilibrium state temperatures, how- ever, there is a major contribution to the dynamical properties of glasses from

Fayer, Michael D.

230

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

231

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

232

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

PubMed

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

Kimberly, David A; Salice, Christopher J

2014-07-01

233

Conformational Analysis of (+)-Germacrene A by Variable Temperature NMR and NOE Spectroscopy  

PubMed Central

(+)-Germacrene A, an important intermediate in sesquiterpene biosynthesis, was isolated in pure form from a genetically engineered yeast and was characterized by chromatographic properties (TLC, GC), MS, optical rotation, UV, IR, 1H NMR and 13C NMR data. Variable-temperature 500 MHz 1H NMR spectra in CDCl3 showed that this flexible cyclodecadiene ring exists as three NMR-distinguishable conformational isomers in a ratio of about 5:3:2 at or below ordinary probe temperature (25° C). The conformer structures were assigned by 1H NMR data comparisons, NOE experiments, and vicinal couplings as follows: 1a (52%, UU), 1b (29% UD), and 1c (19%, DU). PMID:20617157

Faraldos, Juan A.; Wu, Shuiqin; Chappell, Joe

2009-01-01

234

Variability of Drop Size Distributions: TimeScale Dependence of the Variability and Its Effects on Rain Estimation  

Microsoft Academic Search

A systematic and intensive analysis is performed on 5 yr of reliable disdrometric data (over 20 000 one-minute drop size distributions, DSDs) to investigate the variability of DSDs in the Montreal, Quebec, Canada, area. The scale dependence (climatological scale, day to day, within a day, between physical processes, and within a physical process) of the DSD variability and its effect

Gyuwon Lee; Isztar Zawadzki

2005-01-01

235

Seasonal SAM Zonal Asymmetries and their Connection to Antarctic Temperature Variability  

NASA Astrophysics Data System (ADS)

The Southern Hemisphere Annular Mode (SAM) is the dominant mode of climate variability in the extra-tropical Southern Hemisphere. Representing variations in pressure and the corresponding changes to the circumpolar zonal flow, it is typically thought of as an ';annular' or ring-like structure. However, on seasonal timescales the zonal symmetry observed in the SAM in monthly or annual mean data is much less marked. This presentation will examine the seasonal changes in the SAM structure, and explores temperature signals across West Antarctica and the Antarctic Peninsula that are strongly tied to the asymmetric SAM structure. The SAM asymmetries are most marked in the Pacific sector and in austral winter and spring, related to changes in the jet entrance and exit regions poleward of 30S. Depending on the season, the asymmetric SAM structure explains over 25% of the variance in the overall SAM structure and has strong connections with ENSO or zonal wave number 3. Across the Pacific sector, including the Antarctic Peninsula, temperature variations are strongly tied to the asymmetric SAM structure, while temperatures across East Antarctica are more strongly tied to the zonally symmetric SAM structure. This suggests that temperature changes in these regions are more strongly modulated by the asymmetric, meridional circulations rather than changes in the zonal mean flow, in agreement with recent research.

Fogt, R. L.; Jones, J. M.

2013-12-01

236

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

237

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

ERIC Educational Resources Information Center

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

Huddleston, Rich

238

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

PubMed

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

Fisher, Lucy Takesue; Wallhagen, Margaret I

2008-11-01

239

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

Microsoft Academic Search

Advances in high throughput genotyping protocols over the past few years have been remarkable. Most protocols developed to increase the throughput of genotyping rely on fluorescent based technologies for data acquisition and capture. In general, the number of genotypes per day quoted for these protocols are the result of extrapolations based on ideal situations. Here we present our experience with

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

1996-01-01

240

Modeling Day-to-day Trip Choice Evolution under Network Disruption  

E-print Network

more on the evolution process itself, rather than the final (static) equilibrium state, which a potential equilibrium or stable state. This introduces a paradigm shift from viewing transportation sys- tems as occupying an equilibrium state in terms of traveler choices, to viewing transportation systems

Levinson, David M.

241

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 setting. AN EXAMPLE: Let us look at a sample presentation in order to help illustrate the steps of the One) Give Guidance About Errors and Omissions 5) Teach a General Principle 6) Conclusion #12;4 orally. She

Gilbert, Matthew

242

A comparison of award?winning radio commercials and their day?to?day counterparts  

Microsoft Academic Search

What are some of the differences between award?winning radio commercials and those that are judged by those in the trade not to be worthy of an award such as the “CLIO” of the American TV and Radio Commercials Festival? Should music and sound effects be used? What are some of the objectively measured stylistic devices used in the text of

Norman Felsenthal; G. Wayne Shamo; John R. Bittner

1971-01-01

243

"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

244

“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

245

Loneliness and Cortisol: Momentary, Day-to-day, and Trait Associations  

PubMed Central

Summary In attempts to understand the social determinants of health, strong associations have been found between measures of loneliness, physiological stress processes, and physical and mental health outcomes. Feelings of loneliness are hypothesized to have implications for physiological stress processes, including activity of the hypothalamic-pituitary-adrenal (HPA) axis. In a community sample of young adults, multilevel modeling was used to examine whether trait and state feelings of loneliness were related to changes in levels of the stress-sensitive hormone cortisol, and whether the associations between loneliness and cortisol were mediated or moderated by the presence of concurrent depression or high levels of chronic life stress. Results indicated that trait loneliness was associated with a flattening of the diurnal cortisol rhythm. In addition, both daily and momentary state variations in loneliness were related to cortisol. Prior-day feelings of loneliness were associated with an increased cortisol awakening response the next morning and momentary experiences of loneliness during the day were associated with momentary increases in cortisol among youth who also had high chronic interpersonal stress. Results were significant after covarying current depression, both chronic and momentary reports of stress, and medical and lifestyle covariates. This study expanded on prior work by investigating and revealing three different time-courses of association between loneliness and HPA axis activity in young adults: trait, daily and momentary. PMID:19744794

Adam, Emma K.

2009-01-01

246

Variable-temperature powder X-ray diffraction of aromatic carboxylic acid and carboxamide cocrystals.  

PubMed

The effect of temperature on the cocrystallization of benzoic acid (BA), pentafluorobenzoic acid (FBA), benzamide (BAm), and pentafluorobenzamide (FBAm) is examined in the solid state. BA and FBA formed a 1:1 complex 1 at ambient temperature by grinding with a mortar and pestle. Grinding FBA and BAm together resulted in partial conversion into the 1:1 adduct 2 at 28 degrees C and complete transformation into the product cocrystal at 78 degrees C. Further heating (80-100 degrees C) and then cooling to room temperature gave a different powder pattern from that of 2. BAm and FBAm hardly reacted at ambient temperature, but they afforded the 1:1 cocrystal 3 by melt cocrystallization at 110-115 degrees C. Both BA+FBAm (4) and BA+BAm (5) reacted to give new crystalline phases upon heating, but the structures of these products could not be determined owing to a lack of diffraction-quality single crystals. The stronger COOH and CONH2 hydrogen-bonding groups of FBA and FBAm yielded the equimolar cocrystal 6 at room temperature, and heating of these solids to 90-100 degrees C gave a new crystalline phase. The X-ray crystal structures of 1, 2, 3, and 6 are sustained by the acid-acid/amide-amide homosynthons or acid-amide heterosynthon, with additional stabilization from phenyl-perfluorophenyl stacking in 1 and 3. The temperature required for complete transformation into the cocrystal was monitored by in situ variable-temperature powder X-ray diffraction (VT-PXRD), and formation of the cocrystal was confirmed by matching the experimental peak profile with the simulated diffraction pattern. The reactivity of H-bonding groups and the temperature for cocrystallization are in good agreement with the donor and acceptor strengths of the COOH and CONH2 groups. It was necessary to determine the exact temperature range for quantitative cocrystallization in each case because excessive heating caused undesirable phase transitions. PMID:17441188

Reddy, L Sreenivas; Bhatt, Prashant M; Banerjee, Rahul; Nangia, Ashwini; Kruger, Gert J

2007-04-01

247

Mg/Ca ratios in coralline red algae as temperature proxies for reconstructing Labrador Current variability  

NASA Astrophysics Data System (ADS)

Climate and oceanographic changes in the Northwestern Atlantic have recently had a dramatic impact on ecosystems and fishery yields. 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) flowing along the Eastern Canadian coastline. Although interdecadal and interannual variability of SST and salinity in the LC system have been documented, a clear cyclic pattern has not been identified. In order to better understand the observed ecosystem changes and predict future changes in LC flow, a spatial and temporal reconstruction of the LC is needed. This, however, requires reliable long-term and high-resolution temperature records, which are not available from short instrumental observations. Our research is therefore concerned with establishing century-scale sea-surface temperature (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 SST information 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). Age models were established for all specimens by counting annual growth increments, which average 350 microns/year. Mg/Ca ratios range from 0.055 to 0.138 (measured in weight %) and relate to water temperatures of -1 to 10°C. An integration of observed element cycles and age model data yields Mg/Ca-based SST reconstructions dating back to the industrial revolution. Multidecadal spatial correlations of our C. compactum records with satellite-derived sea-surface temperatures clearly indicate the influence of a LC signature on the Mg/Ca time series and highlight the value of the algae as a proxy to resolve large-scale and long-term LC variability.

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

2009-04-01

248

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

249

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

250

Effects of Four Key Process Variables on Size Shrinkages of Low Temperature Co-Fired Ceramic Substrates  

Microsoft Academic Search

The effects of four key process variables on the size shrinkages of low temperature co-fired ceramic substrates were investigated using the methods of design of experiments (DOE), analysis of variance (ANOVA), and multivariable regression. The process variables investigated were raw tape thickness, laminating pressure, coining pressure, and coining time. The results revealed that coining pressure had the most significant effect

Z. W. Zhong; P. Arulvanan; C. K. Goh

2007-01-01

251

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

NASA Astrophysics Data System (ADS)

Geochemical variations in shallow water corals provide a valuable archive of paleoclimatic information. However, biological effects can complicate the interpretation of these proxies, forcing their application to rely on empirical calibrations. Carbonate clumped isotope thermometry (?47) is a novel paleotemperature proxy based on the temperature dependent "clumping" of 13C-18O bonds. Similar ?47-temperature relationships in inorganically precipitated calcite and a suite of biogenic carbonates provide evidence that carbonate clumped isotope variability may record absolute temperature without a biological influence. However, large departures from expected values in the winter growth of a hermatypic coral provided early evidence for possible ?47 vital effects. Here, we present the first systematic survey of ?47 in shallow water corals. Sub-annual Red Sea ?47 in two Porites corals shows a temperature dependence similar to inorganic precipitation experiments, but with a systematic offset toward higher ?47 values that consistently underestimate temperature by ˜8 °C. Additional analyses of Porites, Siderastrea, Astrangia and Caryophyllia corals argue against a number of potential mechanisms as the leading cause for this apparent ?47 vital effect including: salinity, organic matter contamination, alteration during sampling, the presence or absence of symbionts, and interlaboratory differences in analytical protocols. However, intra- and inter-coral comparisons suggest that the deviation from expected ?47 increases with calcification rate. Theoretical calculations suggest this apparent link with calcification rate is inconsistent with pH-dependent changes in dissolved inorganic carbon speciation and with kinetic effects associated with CO2 diffusion into the calcifying space. However, the link with calcification rate may be related to fractionation during the hydration/hydroxylation of CO2 within the calcifying space. Although the vital effects we describe will complicate the interpretation of ?47 as a paleothermometer in shallow water corals, it may still be a valuable paleoclimate proxy, particularly when applied as part of a multi-proxy approach.

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

2012-12-01

252

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

253

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

NASA Technical Reports Server (NTRS)

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

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

2011-01-01

254

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

255

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

256

Using temperature modeling to investigate the temporal variability of riverbed hydraulic conductivity during storm events  

NASA Astrophysics Data System (ADS)

SummaryUnderstanding the impact of storm events on riverbed hydraulic conductivity is crucial in assessing the efficacy of riverbank filtration as a water-treatment option. In this study, the variability of riverbed hydraulic conductivity and its correlation to river stage during storm events was investigated. Water levels and temperatures were continuously monitored in the river using creek piezometers screened beneath the riverbed, and monitoring wells located on the river bank. The range of values for water levels during the study period was from 161.3 to 163.7 m AMSL while temperatures ranged from 3.75 °C to 24 °C. During the duration of the study the Great Miami River was losing water to the underlying aquifer due to pumping in the adjacent municipal well field. Flow and heat transport were simulated in a groundwater heat and flow program VSH2D to determine the hydraulic conductivity of the riverbed. Hydraulic conductivity was estimated by using it as a calibration parameter to match simulated temperatures to observed temperatures in a monitoring well. Hydraulic heads in the aquifer responded to storm events at the same times but with dampened amplitudes compared to the river stage. The relative responses resulted in increased head gradients during the rising limb of the stage-hydrograph. Heat-flow modeling during five storm events demonstrated that a rise in head gradient alone was not sufficient to produce the temperature changes observed in the wells. Simulated temperatures were fitted to the observed data by varying both river stage (as measured in the field) and riverbed hydraulic conductivity. To produce the best fit temperatures, riverbed hydraulic conductivity consistently needed to be increased during the rising and peak stages of the storm events. The increased conductivity probably corresponds to a loss of fine sediments due to scour during high river stage. Hydraulic conductivity increases during storm events varied from a factor of two (0.0951-0.2195 m/d) to almost one order of magnitude (0.0007-0.00658 m/d). Despite these predicted changes the highest model-predicted hydraulic conductivity value was 0.66 m/d, which is still much lower than the infiltration rate used in sand filtration systems (3.59 m/d). These low values suggest that storm events do not pose a significant risk to the water quality at this well field. There was a direct correlation between the duration of rising limb, rate of change of stage and maximum river stage and the magnitude of change of riverbed hydraulic conductivity.

Mutiti, Samuel; Levy, Jonathan

2010-07-01

257

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

258

Thermocline temperature variability in the Timor Strait over the last two glacial cycles  

NASA Astrophysics Data System (ADS)

*Lo Giudice Cappelli, E elgc@gpi.uni-kiel.de Institute of Geosciences, Christian-Albrechts-University, Kiel, Germany Holbourn, A ah@gpi.uni-kiel.de Institute of Geosciences, Christian-Albrechts-University, Kiel, Germany Kuhnt, W wk@gpi.uni-kiel.de Institute of Geosciences, Christian-Albrechts-University, Kiel, Germany Regenberg, M regenberg@gpi.uni-kiel.de Institute of Geosciences, Christian-Albrechts-University, Kiel, Germany Garbe- Schönberg, D dgs@gpi.uni-kiel.de Institute of Geosciences, Christian-Albrechts-University, Kiel, Germany Seafloor temperature variations within the path of the Indonesian Throughflow are mainly influenced by the intensity of the cool throughflow and by glacial-interglacial sea-level changes. We present a study based on core 18471 (9°21.987' S, 129°58.983' E, 485m water depth, 13.5m long) and 30 core tops retrieved in the Timor Sea during the R/V Sonne Cruise 185 ("VITAL"). Multicorer core tops were retrieved along two transects between 130 and 2400m water depths, representing a range of present day bottom water temperatures between 2 and 21°C. For the downcore study, we measured Mg/Ca-ratios in ~10 tests of the benthic foraminifera Hoeglundina elegans, Cibicidoides wuellerstorfi and Hyalinea balthica in 10cm intervals (1-2kyr time resolution). The preservation of tests was checked with a scanning electron microscope. Cibicidoides wuellerstorfi and H. balthica were used in one interval, where H. elegans was rare. Duplicate samples were analyzed to inter-calibrate the three species. Mg/Ca ratios were converted into temperature using published calibrations and our regional calibration based on Timor Sea core tops. Preliminary results show that Mg/Ca ratios in H. elegans vary between 0.8 and 2.2mmol mol-1 corresponding to a temperature range between 4 and 10.5°C, in contrast to a modern annual average temperature of 7.9°C at 400m. 22-paired analyses in H. elegans give a reproducibility of 0.16mmol mol-1 (standard deviation), corresponding to a temperature difference of ±0.9°C. The amplitude of the temperature change during deglaciation is ~2°C between MIS2 and the Holocene and ~3°C between MIS6 and MIS5e. In contrast, the highest amplitude variability (~6.5°C) is detected during MIS3, suggesting transient shutdown of the Indonesian Throughflow leading to thermocline warming.

Lo Giudice Cappelli, E.; Holbourn, A. E.; Kuhnt, W.; Regenberg, M.; Garbe-Schoenberg, C.

2012-12-01

259

Amplification of Surface Temperature Trends and Variability in the Tropical Atmosphere  

NASA Astrophysics Data System (ADS)

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

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

2005-09-01

260

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

NASA Astrophysics Data System (ADS)

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

Mohino, Elsa; Janicot, Serge; Bader, Juergen

2011-08-01

261

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

262

Novel variable-temperature chuck for use in the detection of deep levels in processed semiconductor wafers  

Microsoft Academic Search

This paper describes the design, construction, and characterization of a variable-temperature wafer apparatus for use in the detection of electrically active defects which produce deep levels in the band gap of silicon. In its present form, the wafer chuck can heat and cool wafers as large as 51 mm in diameter over the temperature range from -196 to 350 C.

R. Y. Koyama; M. G. Buehler

1979-01-01

263

Novel variable-temperature chuck for use in the detection of deep levels in processed semiconductor wafers  

Microsoft Academic Search

This paper describes the design, construction, and characterization of a variable-temperature wafer apparatus for use in the detection of electrically active defects which produce deep levels in the band gap of silicon. In its present form, the wafer chuck can heat and cool wafers as large as 51 mm in diameter over the temperature range from ?196° to 350°C. Heating

R. Y. Koyama; M. G. Buehler

1979-01-01

264

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

265

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

266

The roles of surface heat flux and ocean heat transport convergence in determining Atlantic Ocean temperature variability  

Microsoft Academic Search

The temperature variability of the Atlantic Ocean is investigated using an eddy-permitting (1\\/4°) global ocean model (ORCA-025)\\u000a forced with historical surface meteorological fields from 1958 to 2001. The simulation of volume-averaged temperature and\\u000a the vertical structure of the zonally averaged temperature trends are compared with those from observations. In regions with\\u000a a high number of observations, in particular above a

Jeremy P. Grist; Simon A. Josey; Robert Marsh; Simon A. Good; Andrew. C. Coward; Beverly A. de Cuevas; Steven G. Alderson; Adrian L. New; Gurvan Madec

2010-01-01

267

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

NASA Astrophysics Data System (ADS)

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

Rogozhina, I.; Rau, D.

2014-04-01

268

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

269

Long term variability of the Danube River flow and its relation to precipitation and air temperature  

NASA Astrophysics Data System (ADS)

In this work the long cycles and long range dependence of monthly discharge, precipitation and air temperature time series from the Danube River during the years 1901-2006 were analysed using wavelet analysis, with emphasis on wavelet coherence and cross wavelet spectra. All time series were deseasonalized prior to the analysis. Long cycles with 11-15 year periods during almost the whole observed period in discharge and during 1935-1975 in precipitation were found. Furthermore a reappearing four year cycle was found in all discharge time series. No significant long cycles were found in the temperature time series, which on the other hand display long term persistence. The cross-wavelet spectra and the wavelet coherence show strong correlation between the precipitation and discharge spectra in the low frequency intervals. Furthermore, a convolution of precipitation and catchment response function was used to examine the propagation of long cycles from precipitation to discharge. The results show, that the long range dependence in precipitation propagates into discharge and that the precipitation lead in the cross-wavelet spectrum increases with the increasing response time. The results indicate that especially mean monthly precipitation could be used as input variable in order to improve stochastic discharge modelling.

Szolgayova, E.; Parajka, J.; Blöschl, G.; Bucher, C.

2014-11-01

270

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

NASA Astrophysics Data System (ADS)

Interannual to decadal variability of European summer drought and its relationship with global sea surface temperature (SST) is investigated using the newly developed self calibrated Palmer drought severity index (scPDSI) and global sea surface temperature (SST) field for the period 1901-2002. A European drought severity index defined as the average of scPDSI over entire Europe shows quasiperiodic variations in the 2.5-5 year band as well as at 12-13 years suggesting a possible potential predictability of averaged drought conditions over Europe. A Canonical Correlation Analysis between summer scPDSI anomalies over Europe and global SST anomalies reveals the existence of three modes of coupled summer drought scPDSI patterns and winter global SST anomalies. The first scPDSI-SST coupled mode represents the long-term trends in the data which manifest in SST as warming over all oceans. The associated long-term trend in scPDSI suggests increasing drought conditions over the central part of Europe. The second mode is related to the inter-annual ENSO and decadal PDO influence on the European climate and the third one captures mainly the drought pattern associated to Atlantic Multidecadal Oscillation. The lag relationships between winter SST and summer drought conditions established in this study can provide a valuable skill for the prediction of drought conditions over Europe on interannual to decadal time scales.

Ionita, M.; Lohmann, G.; Rimbu, N.; Chelcea, S.; Dima, M.

2012-01-01

271

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

NASA Astrophysics Data System (ADS)

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

Mohino, Elsa; Janicot, Serge; Bader, Juergen

2010-05-01

272

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

273

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.

2014-03-01

274

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

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

275

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

276

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

277

Florida Current surface temperature and salinity variability during the last millennium  

NASA Astrophysics Data System (ADS)

The salinity and temperature of the Florida Current are key parameters affecting the transport of heat into the North Atlantic, yet little is known about their variability on centennial timescales. Here we report replicated, high-resolution foraminiferal records of Florida Current surface hydrography for the last millennium from two coring sites, Dry Tortugas and the Great Bahama Bank. The oxygen isotopic composition of Florida Current surface water (?18Ow) near Dry Tortugas increased 0.4‰ during the course of the Little Ice Age (LIA) (˜1200-1850 A.D.), equivalent to a salinity increase of 0.8-1.5. On the Great Bahama Bank, where surface waters are influenced by the North Atlantic subtropical gyre, ?18Ow increased by 0.3‰ during the last 200 years. Although a portion (˜0.1‰) of this shift may be an artifact of anthropogenically driven changes in surface water ?CO2, the remaining ?18Ow signal implies a 0.4-1 increase in salinity after 200 years B.P. The simplest explanation of the ?18Ow data is southward migration of the Atlantic Hadley circulation during the LIA. Scaling of the ?18Ow records to salinity using the modern low-latitude ?18Ow-S slope produces an unrealistic reversal in the salinity gradient between the two sites. Only if ?18Ow is scaled to salinity using a high-latitude ?18Ow-S slope can the records be reconciled. Variable atmospheric 14C paralleled Dry Tortugas ?18Ow, suggesting that solar irradiance paced centennial-scale migration of the Inter-Tropical Convergence Zone and changes in Florida Current salinity during the last millennium.

Lund, David C.; Curry, William

2006-06-01

278

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

279

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

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

280

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

281

Cataclysmic Variable Primary Effective Temperatures: Constraints on Binary Angular Momentum Loss  

E-print Network

We review the most decisive currently available measurements of the surface effective temperatures, Teff, of white dwarf (WD) primaries in cataclysmic variables (CVs) during accretion quiescence, and use these as a diagnostic for their time averaged accretion rate, . Using time-dependent calculations of the WD envelope, we investigate the sensitivity of the quiescent Teff to long term variations in the accretion rate. We find that the quiescent Teff provides one of the best available tests of predictions for the angular momentum loss and resultant mass transfer rates which govern the evolution of CVs. While gravitational radiation is sufficient to explain the of strongly magnetic CVs at all Porb, faster angular momentum loss is required by the temperatures of dwarf nova primaries (non-magnetic systems). This provides evidence that a normal stellar magnetic field structure near the secondary is essential for the enhanced braking mechanism to work, supporting the well-known stellar wind braking hypothesis. The contrast in is most prominent for orbital periods Porb > 3 hours, above the period gap, but a modest enhancement is also present at shorter Porb. The averaging time which reflects is as much as 10^5 years for low- systems and as little as 10^3 years for high- systems. We discuss the security of conclusions drawn about the CV population in light of these time scales and our necessarily incomplete sample of systems. Measurements for non-magnetic systems above the period gap fall below predictions from traditional stellar wind braking prescriptions, but above more recent predictions with somewhat weaker angular momentum loss. We also discuss the apparently high Teff's found in the VY Scl stars. (abridged)

Dean M. Townsley; Boris T. Gaensicke

2008-11-15

282

Variable Temperature SiO2 Stripes Spectroscopy Taken by Customized Scattering Type Scanning Near-field Optical Microscopy  

NASA Astrophysics Data System (ADS)

Variable temperature scattering-type scanning near-field optical microscopy is the system we built up from basis to explore the phase transition under low temperature. It has advantages of be able to take topography and spectroscopy simultaneously. What the SNOM system measures is the reflective effivient, it is determinde by the dielectric value of the sample, which is an intrinsic chemical propertiy. In this experiment, we taken spectroscopy of a sample with silicon dioxide stripes doped on the silicon substrate, get the contrast of silicon/silison dioxide, which is accord to the prediction of two models. Furthermore, the different contrast under various temperature reveals the temperature dependent dielectric function.

Li, Chaoran

283

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

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

284

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

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

285

Analysis of variability and diurnal range of daily temperature in a nested regional climate model: comparison with observations and doubled CO 2 results  

Microsoft Academic Search

Analysis of daily variability of temperature in climate model experiments is important as a model diagnostic and for determination of how such variability may change under perturbed climate conditions. The latter could be important from a climate impacts perspective. We analyze daily mean, diurnal range and variability of surface air temperature in two continuous 3 1\\/2 year long climate simulations

L. O. Mearns; F. Giorgi; L. McDaniel; C. Shields

1995-01-01

286

Analysis of variability and diurnal range of daily temperature in a nested regional climate model: comparison with observations and doubled CO2 results  

Microsoft Academic Search

Analysis of daily variability of temperature in climate model experiments is important as a model diagnostic and for determination of how such variability may change under perturbed climate conditions. The latter could be important from a climate impacts perspective. We analyze daily mean, diurnal range and variability of surface air temperature in two continuous 3?1\\/2 year long climate simulations over

Mearns LO; F Giorgi; L McDaniel; C Shields

1995-01-01

287

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

288

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

289

Water temperature variability as an indicator of shallow-depth groundwater behaviour in limestone areas in west Malaysia  

NASA Astrophysics Data System (ADS)

The temperatures of groundwaters and surface streams were determined regularly over a 1-yr. period at 139 sampling polints in three limestone areas of the Malay peninsula. The standard deviation (s.d.) of water temperatures recorded at each site provides a measure of temperature variability. Deeper groundwaters exhibit the narrowest temperature fluctuations (s.d. 0.05°C). Shallow-depth groundwaters have a greater temperature variability particularly those, such as vadose streams (mean s.d. 0.27°C) and diffuse-flow seepage in caves (mean s.d. 0.26°C), which encounter circulatory air within the aquifer. Surface streams display much wider fluctuations. Those in tin-mining areas have s.d.-values of over 2.0°C, and this is largely attributed to their small groundwater component and to their banks being mostly unvegetated. Temperature variability is shown to provide a sound basis for characterizing groundwater flow and identifying groundwater components in surface streams.

Crowther, J.; Pitty, A. F.

1982-05-01

290

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

NASA Astrophysics Data System (ADS)

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

Chiba, Ryoichi

2012-02-01

291

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

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

292

Seasonal to tidal variability of currents and temperature in waters of the continental slope, southeastern Bay of Biscay  

NASA Astrophysics Data System (ADS)

Since 2007, high temporal resolution time-series of currents, temperature and salinity, from two oceanic moorings, have provided information on the local water column dynamics and hydrography, over the slope of the southeastern part of the Bay of Biscay. In this study, these data are analysed to describe the variability observed in currents and stratification conditions, at different time scales. A well-defined seasonal cycle is the dominant signal in temperature and salinity, with a surface mixed layer that shows temperatures over 20 °C, low salinities and depths between 30 and 50 m from July to September. Likewise, currents present marked seasonal and mesoscale variability. The most intense currents, oriented to the E-SE, occur from November to January, when the Iberian Poleward Current is sampled by both moorings. Much weaker currents, mainly oriented to the SW, are observed during the stratified months. Vertically, the flow is markedly barotropic and shows low variability at that scales, although vertical coherence decreases for the stratified period and significant vertical variability linked to high frequency processes is observed. Since energy contents around the main tidal peaks are lower than in other areas of the Bay, the contribution of the inertial band to the high frequency variability appears to be especially important in this region. The results obtained suggest that inertial oscillations contribute significantly to the vertical shear during the stratified period and might have a significant role in favouring the vertical mixing over the area.

Rubio, A.; Fontán, A.; Lazure, P.; González, M.; Valencia, V.; Ferrer, L.; Mader, J.; Hernández, C.

2013-01-01

293

Pacific sea surface temperatures in the twentieth century: Variability, trend, and connections to long-term hydroclimate variations over the Great Plains  

Microsoft Academic Search

Pacific sea surface temperatures (SSTs) exhibit variability on interannual to centennial time scales. This dissertation addresses the challenge to separate SST natural variability from the nonstationary (largely anthropogenic) warming trend; and, based on the clarified variability\\/trend patterns, evaluate SST forcing of long-term hydroclimate variations over the Great Plains. First, a consistent analysis of natural variability and secular trend in the

Bin Guan

2008-01-01

294

Electrical characterization of transition metal silicide nanostructures using variable temperature scanning probe microscopy  

NASA Astrophysics Data System (ADS)

Cobalt disilicide (CoSi2) islands have been formed on Si(111) and Si(100) through UHV deposition and annealing. Current-voltage (I-V) and temperature-dependent current-voltage (I-V-T) curves have been measured on the islands using conducting atomic force microscopy ( c-AFM) with a doped diamond like carbon cantilever. Thermionic emission theory has been applied to the curves and the Schottky barrier heights, phi B, and ideality factors, n, for each island have been calculated. Barrier heights and ideality factors are evaluated as functions of temperature, island area, and each other. While all islands were prepared in UHV conditions, one set was removed from UHV and measurements were performed in ambient conditions while the other set remained in UHV. The islands measured in ambient conditions were known as "air-exposed samples" due to the fact that the surface was assumed to be passivated upon exposure to atmospheric conditions. The islands measured in UHV were known as "clean samples" because the surface was not passivated. Air-exposed samples were CoSi2 islands on Si(111) and exhibited a negative linear correlation between the barrier height and the ideality factor. Measured values of phiB on the air-exposed samples approached reported bulk values. Measurements from CoSi2 islands on clean Si(111) and Si(100) revealed no correlation between phiB and n. Furthermore, it was observed that the measured barrier heights of CoSi2 islands on clean Si surfaces are ˜0.2--0.3 eV less than the barrier heights measured from CoSi2 islands on air-exposed surfaces. This negative shift in the clean surface barrier heights was attributed to Fermi level pinning by the non-passivated silicon surface states. Additionally, a slight trend toward lower barrier height as a function of decreasing island area was detected in all samples. This trend is attributed to increased hole injection and generation-recombination in the smaller islands, but it may also be due to effects caused by increased spreading resistance as the island size decreases. Non-linearity in activation energy plots, as well as correlations between decreasing barrier height and decreasing island area-to-island periphery ratio, are attributed to generation-recombination. These measurements indicate that the Schottky barrier height decreases and ideality factor increases with decreasing temperature, even if there is no direct linear correlation between phiB and n. These temperature-dependent relationships are attributed primarily to hole injection and generation-recombination, with barrier height inhomogeneity as a minor effect. Titanium silicide (TiSi2) islands have been formed by UHV deposition of titanium on atomically flat Si(100) and Si(111). Scanning tunneling microscopy (STM), scanning tunneling spectroscopy (STS), and a variant of current imaging tunneling spectroscopy (CITS) have been used to characterize single electron tunneling (SET) through the islands. SET is observed to occur in the islands and is evaluated based on the predictions of the orthodox model. The observation of SET suggests that the Schottky barrier could be effective in future SET-based electronic devices. SET was not observed as often as expected, however, suggesting that there is a mechanism limiting SET. Possible mechanisms for SET limiting are evaluated and it is concluded that SET is limited due to a combination of Schottky barrier lowering, a low resistance substrate, and Fermi level pinning by the non-passivated surface states of the silicon. These factors make SET in TiSi2 islands on silicon potentially too variable to be used in future devices unless the SET-limiting mechanism is resolved.

Tedesco, Joseph Leo

295

Pacific Ocean sea-surface temperature variability and predictability of rainfall in the early and late parts  

E-print Network

between All India Summer Monsoon Rainfall and typical indices for the El Nin~o-Southern Oscillation (ENSOPacific Ocean sea-surface temperature variability and predictability of rainfall in the early and late parts of the Indian summer monsoon season Balaji Rajagopalan · Peter Molnar Received: 20 May 2011

Mojzsis, Stephen J.

296

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

297

InGaN/GaN quantum wells studied by high pressure, variable temperature, and excitation power spectroscopy  

E-print Network

InGaN/GaN quantum wells studied by high pressure, variable temperature, and excitation power by metalorganic chemical vapor deposition MOCVD on a sapphire substrate, on top of a 1.85 m thick GaN layer. Three

Weinstein, Benard.A.

298

Long term variability of the annual hydrological regime and sensitivity to temperature phase shifts in Saxony\\/Germany  

Microsoft Academic Search

The timing of the seasons strongly effects ecosystems and human activities. Recently, there is increasing evidence of changes in the timing of the seasons, such as earlier spring seasons detected in phenological records, advanced seasonal timing of surface temperature, earlier snow melt or streamflow timing. For water resources management there is a need to quantitatively describe the variability in the

M. Renner; C. Bernhofer

2011-01-01

299

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

E-print Network

received 1 October 2012, in final form 14 February 2013) ABSTRACT The Atlantic multidecadal oscillation multidecadal oscillation (AMO), which is a basinwide mode in the entire North Atlantic and is definedMultidecadal Ocean Temperature and Salinity Variability in the Tropical North Atlantic: Linking

Wang, Chunzai

300

Paleoclimate proxy perspective on Caribbean climate since the year 1751: Evidence of cooler temperatures and multidecadal variability  

E-print Network

Atlantic Variabil- ity (TAV), and the North Atlantic Oscillation (NAO)/Arctic Oscillation system [Marshall temperatures and multidecadal variability K. H. Kilbourne,1 T. M. Quinn,2,3 R. Webb,4 T. Guilderson,5,6 J at centennial time scales. A strong multidecadal salinity signal in the oxygen isotope data correlates

South Florida, University of

301

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

E-print Network

26 #12;1 Abstract27 28 In this paper, simulated variability of the Atlantic Multidecadal Oscillation1 Multidecadal North Atlantic Sea Surface Temperature and Atlantic Meridional2 Overturning the delayed36 advective oscillation proposed for the AMOC on multidecadal timescales. A speed up (slow37 down

302

Seasonal and interannual variability of oceanographic processes in the Gulf of Guinea: An investigation using AVHRR sea surface temperature data  

Microsoft Academic Search

The Gulf of Guinea is situated in a critical position for understanding Atlantic equatorial dynamics. This study investigates seasonal and interannual variability in sea surface temperature (SST) throughout this region, focusing on dynamical ocean processes. A 10.5-year time series of remotely sensed SST data with 4 km spatial resolution from the Advanced Very High Resolution Radiometer (AVHRR) were used for

N. J. Hardman-Mountford; J. M. McGlade

2003-01-01

303

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

Microsoft Academic Search

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

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

2005-01-01

304

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

305

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

306

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

307

Spatial patterns in seasonal and interannual variability of chlorophyll and sea surface temperature in the California Current  

E-print Network

Spatial patterns in seasonal and interannual variability of chlorophyll and sea surface temperature of the CCS. Using six years (1997­2003) of daily SST and chlorophyll imagery, we map the spatial dependence, where weak cycles of SST fluctuate between spring minima and late summer maxima and chlorophyll peaks

Thomas, Andrew

308

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

NASA Astrophysics Data System (ADS)

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

309

Variable-temperature Raman spectroscopic study of the hydrogen sensing mechanism in Pt-WO3 nanowire film  

NASA Astrophysics Data System (ADS)

Two special properties of Pt coated WO3 (Pt-WO3) nanowire film for sensing hydrogen gas flow in air are reported in this paper, including the large relative resistance change (close to 100%) and the dependence of the millisecond-scale response time on operating temperature. A variable-temperature Raman spectroscopic system is applied to record the structural changes of WO3 nanowires in situ during the input of H2 gas at different operating temperatures. Furthermore, based on the experimental results, two combined models are proposed to be responsible for the hydrogen sensing mechanism in Pt-WO3 nanowire film.

Yi Luo, Jian; Xian Chen, Xue; Da Li, Wei; Yuan Deng, Wei; Li, Wei; Yuan Wu, Hao; Feng Zhu, Lian; Guang Zeng, Qing

2013-03-01

310

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

SciTech Connect

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

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

1995-02-01

311

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

2014-01-01

312

Urban heat islands in China and decadal-scale temperature variability  

SciTech Connect

The paper describes an investigation involving careful examination of data homogeneity and calculation of urban heat island effects in Chinese surface temperatures. As part of this study, monthly mean temperatures, mean minimum temperatures, and mean maximum temperatures from more than 400 stations were collected and merged. Large seasonal and regional variations were shown; however, results indicate that urban heat island biases are greatest in magnitude during the coldest months. The biases in monthly mean temperature and in mean diurnal temperature range have increased since the 1950s, while those in the minimum temperature appear to have decreased. These changes are significant in comparison to the interdecadal fluctuations during the same 40-year time period. Despite large variations, preliminary results suggest that the Chinese urban heat islands not only produce a warm bias in monthly mean temperature, but also constitute a principal source of the persistent decrease in mean diurnal temperature range.

Portman, D.A. [AER, Inc., Cambridge, MA (United States)

1997-11-01

313

Joint Variability of Global Runoff and Global Sea Surface Temperatures GREGORY J. MCCABE  

E-print Network

with the Atlantic multidecadal oscillation (AMO). Corresponding author address: Gregory J. McCabe, U.S. Geo- logical% of the total variance and reflects variability of the El Nin~o­ Southern Oscillation (ENSO) and its associated and indicates a response of global annual runoff to variability in North Atlantic SSTs. The association between

314

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

315

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

316

The association between the BWA index and winter surface temperature variability over eastern Canada and west Greenland  

NASA Astrophysics Data System (ADS)

Since about 1970, winter surface temperature data from stations on coastal eastern Canada and western Greenland have shown detectable decadal cooling. In this study, we attempt to understand some aspect of this surface cooling trend by relating it to the variability of the Canadian Polar Trough (CPT). In order to facilitate the relationship, we introduce a new 50 kPa index called the Baffin Island-West Atlantic (BWA) index which, although reflecting the variability of the western structure of the North Atlantic Oscillation (NAO), is found to explain temperature variability better in north-eastern North America than the structure characterized by the NAO index.The decadal variability in the winter surface temperature is found to be associated with the BWA index at a statistically significant correlation of 0.85. Two distinctive winter climate regimes are found to exist in the climate record from 1947 to 1995, one before and one after about 1970. Although the magnitude of the variance does not change significantly from one regime to the next, the two regimes are characterized by statistically significantly different means and by two distinct spectral signatures. Variability before 1970 is dominated by interannual fluctuations, whereas afterwards much of the contribution to the variability comes from interdecadal fluctuations.Subtraction of the 1947-1969 winter 50 kPa mean height field from the 1970-1995 mean field shows that the change in the height field over the Northern Hemisphere is reflected in the enhancement of the negative phase of the NAO mode (which corresponds to a strong jet stream over the western Atlantic and a strong Icelandic low) and of the positive phase of the Pacific/North America (PNA) mode.

Shabbar, Amir; Higuchi, Kaz; Skinner, Walter; Knox, John L.

1997-09-01

317

OVA-induced airway hyperresponsiveness alters murine heart rate variability and body temperature  

PubMed Central

Altered autonomic (ANS) tone in chronic respiratory disease is implicated as a factor in cardiovascular co-morbidities, yet no studies address its impact on cardiovascular function in the presence of murine allergic airway (AW) hyperresponsiveness (AHR). Since antigen (Ag)-induced AHR is used to model allergic asthma (in which ANS alterations have been reported), we performed a pilot study to assess measurement feasibility of, as well as the impact of allergic sensitization to ovalbumin (OVA) on, heart rate variability (HRV) in a murine model. Heart rate (HR), body temperature (TB), and time- and frequency-domain HRV analyses, a reflection of ANS control, were obtained in chronically instrumented mice (telemetry) before, during and for 22 h after OVA or saline aerosolization in sensitized (OVA) or Alum adjuvant control exposed animals. OVA mice diverged significantly from Alum mice with respect to change in HR during aerosol challenge (P < 0.001, Two-Way ANOVA; HR max change Ctrl = +80 ± 10 bpm vs. OVA = +1 ± 23 bpm, mean ± SEM), and displayed elevated HR during the subsequent dark cycle (P = 0.006). Sensitization decreased the TB during aerosol challenge (P < 0.001). Sensitized mice had decreased HRV prior to challenge (SDNN: P = 0.038; Low frequency (LF) power: P = 0.021; Low/high Frequency (HF) power: P = 0.042), and increased HRV during Ag challenge (RMSSD: P = 0.047; pNN6: P = 0.039). Sensitized mice displayed decreased HRV subsequent to OVA challenge, primarily in the dark cycle (RMSSD: P = 0.018; pNN6: P ? 0.001; LF: P ? 0.001; HF: P = 0.040; LF/HF: P ? 0.001). We conclude that implanted telemetry technology is an effective method to assess the ANS impact of allergic sensitization. Preliminary results show mild sensitization is associated with reduced HRV and a suppression of the acute TB-response to OVA challenge. This approach to assess altered ANS control in the acute OVA model may also be beneficial in chronic AHR models. PMID:23227012

Domnik, N. J.; Seaborn, G.; Vincent, S. G.; Akl, S. G.; Redfearn, D. P.; Fisher, J. T.

2012-01-01

318

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

319

Mid- to late Holocene changes in tropical Atlantic temperature seasonality and interannual to multidecadal variability documented in southern Caribbean corals  

NASA Astrophysics Data System (ADS)

Proxy reconstructions of tropical Atlantic sea surface temperature (SST) that extend beyond the period of instrumental observations have primarily focused on centennial to millennial variability rather than on seasonal to multidecadal variability. Here we present monthly-resolved records of Sr/Ca (a proxy of SST) from fossil annually-banded Diploria strigosa corals from Bonaire (southern Caribbean Sea). The individual corals provide time-windows of up to 68 years length, and the total number of 295 years of record allows for assessing the natural range of seasonal to multidecadal SST variability in the western tropical Atlantic during snapshots of the mid- to late Holocene. Comparable to modern climate, the coral Sr/Ca records reveal that mid- to late Holocene SST was characterised by clear seasonal cycles, persistent quasi-biennial and prominent interannual as well as inter- to multidecadal-scale variability. However, the magnitude of SST variations on these timescales has varied over the last 6.2 ka. The coral records show increased seasonality during the mid-Holocene consistent with climate model simulations indicating that southern Caribbean SST seasonality is induced by insolation changes on orbital timescales, whereas internal dynamics of the climate system play an important role on shorter timescales. Interannual SST variability is linked to ocean-atmosphere interactions of Atlantic and Pacific origin. Pronounced interannual variability in the western tropical Atlantic is indicated by a 2.35 ka coral, possibly related to a strengthening of the variability of the El Niño/Southern Oscillation throughout the Holocene. Prominent inter- to multidecadal SST variability is evident in the coral records and slightly more pronounced in the mid-Holocene. We finally argue that our coral data provide a target for studying Holocene climate variability on seasonal and interannual to multidecadal timescales, when using further numerical models and high-resolution proxy data.

Giry, Cyril; Felis, Thomas; Kölling, Martin; Scholz, Denis; Wei, Wei; Lohmann, Gerrit; Scheffers, Sander

2012-05-01

320

A temperature-based variable for monitoring outdoor coil airflow in an air-source heat pump during frost-forming conditions  

SciTech Connect

Frost-buildup tests were conducted on a 3-ton (10.6kW) nominal cooling capacity air-source heat pump with an orifice expansion device. This study was conducted to determine if a simple temperature-based control variable could be used to determine the amount of degradation in the outdoor airflow (and heating capacity) of the unit. Refrigerant pressures and temperatures were monitored through-out the system in addition to power requirements and airflow rates. A temperature-based variable was developed that could be used to predict airflow degradation across the outdoor heat exchanger. This variable was defined using the difference between ambient air temperature and a measured refrigerant temperature. Eight refrigerant temperatures in the system were recorded and evaluated. Plots of airflow as a function of this temperature variable, along with plots of the absolute value percent changes of this temperature variable and airflow, were evaluated to determine which refrigerant temperatures could best be used in the variable to predict degradation in airflow. The best fit between the temperature-based variable and airflow degradation occurred with the inclusion of the refrigerant temperature at the outlet from the evaporator. Calculations of percent changes based on values sampled after a defrost showed a polynomial or linear relationship between airflow and the temperature-based variable. Data from two previously tested heat pumps were also used to compare changes in the outdoor airflow to changes in the temperature-based variable. The base-case heat pump and another heat pump both used an orifice as the expansion device in the heating mode. A third heat pump, which used a thermostatic expansion valve (TXV) as the expansion device in the heating mode, failed to show the same goodness of fit between airflow and the temperature-based variable.

Payne, W.V. II; O`Neal, D.L. [Texas A and M Univ., College Station, TX (United States). Energy Systems Lab.

1994-12-31

321

A comparison of surface air temperature variability in three 1000-Yr. coupled ocean-atmosphere model integrations  

SciTech Connect

This study compares the variability of surface air temperature in three long coupled ocean-atmosphere general circulation model integrations. It is shown that the annual mean climatology of the surface air temperatures (SAT) in all three models is realistic and the linear trends over the 1,000-yr integrations are small over most areas of the globe. Second, although there are notable differences among the models, the models' SAT variability is fairly realistic on annual to decadal timescales, both in terms of the geographical distribution and of the global mean values. A notable exception is the poor simulation of observed tropical Pacific variability. In the HadCM2 model, the tropical variability is overestimated, while in the GFDL and HAM3L models, it is underestimated. Also, the ENSO-related spectral peak in the globally averaged observed SAT differs from that in any of the models. The relatively low resolution required to integrate models for long time periods inhibits the successful simulation of the variability in this region. On timescales longer than a few decades, the largest variance in the models is generally located near sea ice margins in high latitudes, which are also regions of deep oceanic convection and variability related to variations in the thermohaline circulation. However, the exact geographical location of these maxima varies from model to model. The preferred patterns of interdecadal variability that are common to all three coupled models can be isolated by computing empirical orthogonal functions (EOFs) of all model data simultaneously using the common EOF technique. A comparison of the variance each model associated with these common EOF patterns shows that the models generally agree on the most prominent patterns of variability. However, the amplitudes of the dominant models of variability differ to some extent between the models and between the models and observations. For example, two of the models have a mode with relatively large values of the same sign over most of the Northern Hemisphere midlatitudes. This mode has been shown to be relevant for the separation of the temperature response pattern due to sulfate aerosol forcing from the response to greenhouse gas forcing.

Stouffer, R.J.; Hegerl, G.; Tett, S.

2000-02-01

322

Simulated Future Air Temperature and Precipitation Climatology and Variability in the Mediterranean Basin by Using Downscaled Global Climate Model Outputs  

NASA Astrophysics Data System (ADS)

The Mediterranean Basin is one of the regions that shall be affected most by the impacts of the future climate changes on temperature regime including changes in heat waves intensity and frequency, seasonal and interannual precipitation variability including changes in summer dryness and drought events, and hydrology and water resources. In this study, projected future changes in mean air temperature and precipitation climatology and inter-annual variability over the Mediterranean region were simulated. For performing this aim, the future changes in annual and seasonal averages for the future period of 2070-2100 with respect to the period from 1970 to 2000 were investigated. Global climate model outputs of the World Climate Research Program's (WCRP's) Coupled Model Intercomparison Project Phase 3 (CMIP3) multi-model dataset were used. SRES A2, A1B and B1 emission scenarios' outputs of the Intergovernmental Panel on Climate Change (IPCC) were used in future climate model projections. Future surface mean air temperatures of the larger Mediterranean basin increase mostly in summer and least in winter, and precipitation amounts decreases in all seasons at almost all parts of the basin. Future climate signals for surface air temperatures and precipitation totals will be much larger than the inter-model standard deviation. Inter-annual temperature variability increases evidently in summer season and decreases in the northern part of the domain in the winter season, while precipitation variability increases in almost all parts of domain. Probability distribution functions are found to be shifted and flattened for future period compared to reference period. This indicates that occurrence frequency and intensity of extreme weather conditions will increase in the future period. This work has been supported by Bogazici University BAP under project number 7362. One of the authors (MLK) was partially supported by Mercator-IPC Fellowship Program.

Ozturk, Tugba; Pelin Ceber, Zeynep; Türke?, Murat; Kurnaz, M. Levent

2014-05-01

323

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

NASA Astrophysics Data System (ADS)

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

Ryu, Jung-Hee; Hayhoe, Katharine

2014-10-01

324

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

325

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

326

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

327

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

328

Power optimization of an irreversible closed intercooled regenerated brayton cycle coupled to variable-temperature heat reservoirs  

Microsoft Academic Search

In this paper, power is optimized for an irreversible closed intercooled regenerated Brayton cycle coupled to variable-temperature heat reservoirs in the viewpoint of the theory of thermodynamic optimization (or finite-time thermodynamics (FTT), or endoreversible thermodynamics, or entropy generation minimization (EGM)) by searching the optimum intercooling pressure ratio and the optimum heat conductance distributions among the four heat exchangers (the hot-and

Wenhua Wang; Lingen Chen; Fengrui Sun; Chih Wu

2005-01-01

329

Paleoclimate proxy perspective on Caribbean climate since the year 1751: Evidence of cooler temperatures and multidecadal variability  

Microsoft Academic Search

Annually resolved coral ?18O and Sr\\/Ca records from southwestern Puerto Rico are used to investigate Caribbean climate variability between 1751 and 2004 C.E. Mean surface ocean temperatures in this region have increased steadily by about 2°C since the year 1751, with Sr\\/Ca data indicating 2.1 ± 0.8°C and ?18O data indicating 2.7 ± 0.5°C. Coral geochemical records from across the

K. H. Kilbourne; T. M. Quinn; R. Webb; T. Guilderson; J. Nyberg; A. Winter

2008-01-01

330

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.

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

2014-01-01

331

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

332

Sensitivity of summer stream temperatures to climate variability in the Pacific Northwest  

NASA Astrophysics Data System (ADS)

the thermal response of streams to a warming climate is important for prioritizing native fish conservation efforts. While there are plentiful estimates of air temperature responses to climate change, the sensitivity of streams, particularly small headwater streams, to warming temperatures is less well understood. A substantial body of literature correlates subannual scale temperature variations in air and stream temperatures driven by annual cycles in solar angle; however, these may be a low-precision proxy for climate change driven changes in the stream energy balance. We analyzed summer stream temperature records from forested streams in the Pacific Northwest for interannual correlations to air temperature and standardized annual streamflow departures. A significant pattern emerged where cold streams always had lower sensitivities to air temperature variation, while warm streams could be insensitive or sensitive depending on geological or vegetation context. A pattern where cold streams are less sensitive to direct temperature increases is important for conservation planning, although substantial questions may yet remain for secondary effects related to flow or vegetation changes induced by climate change.

Luce, Charles; Staab, Brian; Kramer, Marc; Wenger, Seth; Isaak, Dan; McConnell, Callie

2014-04-01

333

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

334

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

335

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

Microsoft Academic Search

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

Arun Kumar; Ants Leetmaa; Ming Ji

1994-01-01

336

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

337

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

338

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

339

Interannual Variability of River Temperature and Energy Flux Across the Russian Arctic Watersheds  

NASA Astrophysics Data System (ADS)

River systems are a vital network connection between terrestrial and ocean systems, transporting freshwater, nutrients, and sediments, from the land to the sea. Many large-scale regional and global studies have been done concerning the origin and fate of nutrients, sediments, and pollutants in rivers, but very few studies have addressed the temperature profile of these river systems. Water temperature is impacted by factors such as air temperature, land cover type, land use changes, human modifications (e.g. dams, industrial activities, municipal discharge), and it has an important influence on the quality and ecology of streams and rivers. Arctic river temperature data would be used by oceanographers to produce more accurate ocean simulations, by resource managers (e.g., fisheries managers), and potentially by the global change community as a signal of warming. In this paper we will present seasonal and interannual trends of decadal (~10 day interval) river temperature and daily discharge data from 20 sites covering all major Russian Arctic Ocean drainage basins. For these 20 sites, records go back as far as 1929 in some cases for temperature (with 913 station years of water temperature data), and back as far as 1917 for discharge.

Pundsack, J. W.; Lammers, R. B.; Shiklomanov, A. I.

2006-12-01

340

Atomistic approach to variability of bias-temperature instability in circuit simulations  

Microsoft Academic Search

A blueprint for an atomistic approach to introducing time-dependent variability into a circuit simulator in a realistic manner is demonstrated. The approach is based on previously proven physics of stochastic properties of individual gate oxide defects and their impact on FET operation. The proposed framework is capable of following defects with widely distributed time scales (from fast to quasi-permanent), thus

B. Kaczer; S. Mahato; V. Valduga de Almeida Camargo; M. Toledano-Luque; Ph. J. Roussel; T. Grasser; F. Catthoor; P. Dobrovolny; P. Zuber; G. Wirth; G. Groeseneken

2011-01-01

341

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

Microsoft Academic Search

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

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

2009-01-01

342

The microstructural response of quartz and Feldspar under shock loading at variable temperatures  

SciTech Connect

Shock recovery experiments were carried out on Westerly granite and Hospital Hill quartzite targets in the peak pressure range 8 to 25 GPa, preshock temperatures of 25{degrees}, 450{degrees}, and 750{degrees}C and pulse durations of 2 to 7 {mu}s using internally heated momentum traps and explosive plane wave generators. Optical and transmission electron microscopy analyses of quartz and feldspar shocked at 25{degrees}C revealed the previously documented progression, with increasing pressure: fracturing; planar fractures and shock mosaicism; shock mosaicism and planar deformation features (PDFs); and isotropization. This same sequence is observed for experiments at elevated preshock temperature but with specific microstructures occurring at lower pressures than those in previous experiments at room temperature. At 750{degrees}C, strong shock mosaicism, partially thermally recovered, is characteristic of feldspar shocked to 8 GPa, whereas 15 GPa is required for its development in quartz and for the generation of PDFs in both minerals. The results suggest that threshold pressures for formation of the various microstructures and phases are expected to vary systematically as a function of the preshock temperature of the target material. We suggest that PDFs are generated in the shock transition by progressive, heterogeneous, phase transformation of the crystal structure to form dense glass or high pressure polymorphs. The onset pressures for PDFs in specific crystallographic orientations is not influenced strongly by temperature, but the character of the PDFs does change as preshock temperature is increased at the same peak shock stress. The change from multiple sets of thin PDFs at low temperature to thicker single sets of PDFs at moderate transformation mechanism as a function of temperature. In contrast, development of shock mosaicism in quartz and feldspar occurs throughout the duration of shock loading and is better developed at elevated temperatures.

Huffman, A.R. [Exxon Exploration Co., Houston, TX (United States); Brown, J.M. [Univ. of Washington, Seattle, WA (United States); Carter, N.L. [Texas A& M Univ. College Station, TX (United States); Reimold, W.U. [Univ. of the Witwatersrand, Johannesburg (South Africa)

1993-12-10

343

Remotely sensed sea surface temperature variability off California during a ``Santa Ana'' clearing  

NASA Astrophysics Data System (ADS)

During a prolonged clearing with particularly dry atmospheric conditions over the Southern California Bight, four NOAA 6 satellite overpasses at 12-hour intervals were recorded while a research vessel measured ocean temperatures within the field of view of the satellite. This data set is used to evaluate two versions of an equation for estimating sea surface temperature from satellite data and for examining short-term changes in surface temperature caused by diurnal variation and surface layer movement. Surface temperatures calculated from data taken during a daytime overpass, using two slightly differing versions of a multiwindow atmospheric correction equation, match the ocean temperatures within the expected range of scatter: ±0.6°C. One version has a mean daytime bias of +0.5°C, the other has -0.4°C, and thus the two versions differ by 0.9°C. The satellite-derived sea surface temperatures show a diurnal variation in the range of 0.25° to 1.0°C. Hence the bias of calculated satellite temperatures for the nighttime overpasses differ from those for the daytime; the bias in one version is +1.2°C and in the other is +0.4°C. It is suggested that these biases are caused by inherent problems in the selection and matching of satellite and ocean data sets used to determine the equation coefficients as well as poorly understood diurnal variation of the surface temperature as measured by satellite. Advection, evidenced by an image-to-image shift of thermal gradients over 12- and 24-hour periods can produce local temperature changes that add to the problem. Noise in one of the satellite data channels, another part of the problem, is shown to be amenable to filtering techniques. Diurnal differences in satellite-observed surface temperatures are found to vary regionally; larger variation is found in waters that are turbid and have a shallow thermocline. Near surface in situ temperature measurements suggest a diurnal layer variation of 0.2°C, much less than the variation observed by satellite. An estimation of diurnal sea surface temperature variation based on heat budget calculations supports the in situ observations.

Lynn, Ronald J.; Svejkovsky, Jan

1984-09-01

344

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

SciTech Connect

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

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

1994-10-07

345

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

346

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

347

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

348

Variability of the Surface Circulation and Temperature in the Adriatic Sea.  

National Technical Information Service (NTIS)

My long-term goals are to contribute to the understanding of the dynamics of marginal seas such as the Adriatic by collecting and interpreting observations of currents and water mass properties (e.g., temperature, salinity, chlorophyll concentration). In ...

P. Poulain

1998-01-01

349

Variable temperature neutron diffraction and x-ray charge density studies of tetraacetylethane.  

SciTech Connect

Single crystal neutron diffraction data have been collected on a sample of enolized 3,4-diacetyl-2,5-hexanedione (tetraacetylethane, TAE) at five temperatures between 20 and 298 K to characterize the temperature-dependent behavior of the short, strong, intramolecular hydrogen bond. Upon decreasing the temperature from 298 K to 20 K, the O2-H1 distance decreases from 1.171(11) to 1.081(2) {angstrom} and the O1 {hor_ellipsis} H1 distance increases from 1.327(10) to 1.416(6) {angstrom}. The convergence of the C?O bond lengths from inequivalent distances at low temperature to identical values (1.285(4) {angstrom}) at 298 K is consistent with a resonance-assisted hydrogen bond. However, a rigid bond analysis indicates that the structure at 298 K is disordered. The disorder vanishes at lower temperatures. Short intermolecular C?H {hor_ellipsis} O contacts may be responsible for the ordering at low temperature. The intramolecular O {hor_ellipsis} O distance (2.432 0.006 {angstrom}) does not change with temperature. X-ray data at 20 K were measured to analyze the charge density and to gain additional insight into the nature of the strong hydrogen bond. Quantum mechanical calculations demonstrate that periodic boundary conditions provide significant enhancement over gas phase models in that superior agreement with the experimental structure is achieved when applying periodicity. One-dimensional potential energy calculations followed by quantum treatment of the proton reproduce the location of the proton nearer to the O2 site reasonably well, although they overestimate the O?H distance at low temperatures. The choice of the single-point energy calculation strategy for the proton potential is justified by the fact that the proton is preferably located nearer to O2 rather than being equally distant to O1 and O2 or evenly distributed (disordered) between them.

Piccoli, P. M. B.; Koetzle, T. F.; Schultz, A. J.; Zhurova, E. A.; Stare, J.; Pinkerton, A. A.; Eckert, J.; Hadzi, D.; Univ. of Toledo; National Inst. of Chemistry; Univ. of California at Santa Barbara

2008-07-24

350

The surface temperatures of Earth: steps towards integrated understanding of variability and change  

NASA Astrophysics Data System (ADS)

Surface temperature is a key aspect of weather and climate, but the term may refer to different quantities that play interconnected roles and are observed by different means. In a community-based activity in June 2012, the EarthTemp Network brought together 55 researchers from five continents to improve the interaction between scientific communities who focus on surface temperature in particular domains, to exploit the strengths of different observing systems and to better meet the needs of different communities. The workshop identified key needs for progress towards meeting scientific and societal requirements for surface temperature understanding and information, which are presented in this community paper. A "whole-Earth" perspective is required with more integrated, collaborative approaches to observing and understanding Earth's various surface temperatures. It is necessary to build understanding of the relationships between different surface temperatures, where presently inadequate, and undertake large-scale systematic intercomparisons. Datasets need to be easier to obtain and exploit for a wide constituency of users, with the differences and complementarities communicated in readily understood terms, and realistic and consistent uncertainty information provided. Steps were also recommended to curate and make available data that are presently inaccessible, develop new observing systems and build capacities to accelerate progress in the accuracy and usability of surface temperature datasets.

Merchant, C. J.; Matthiesen, S.; Rayner, N. A.; Remedios, J. J.; Jones, P. D.; Olesen, F.; Trewin, B.; Thorne, P. W.; Auchmann, R.; Corlett, G. K.; Guillevic, P. C.; Hulley, G. C.

2013-12-01

351

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

352

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

353

The role of surface and advective heat and salt fluxes in the variability of North Sea temperature and salinity  

NASA Astrophysics Data System (ADS)

The objective of this study is to understand the various roles played by the local air-sea exchange processes and the oceanic advection for changes in temperature and salinity of the North Sea. The results are obtained from a three-dimensional model with a resolution of approximately 3 km of the North Sea over the period 1952 - 2001. The simulation is validated by means of observed hydrography and volume fluxes and demonstrated that the model is able to reproduce reasonable results. Oceanic advection shows different effects on temperature and salinity changes. The seasonal surface heat flux (Qsur) is larger than advective heat flux (Qadv) over much of the North Sea, except in the region of the Norwegian Trench. In winter and spring, Qadv warms the North Sea through the northern entrance and the English Channel, where in summer and autumn. Qadv shows advective cooling Surface salt flux is much smaller than advective salt flux in the whole North Sea. This indicates that changes in salinity are controlled more by advection than by the precipitation-evaporation balance in the North Sea. In most parts of the North Sea, the seasonal variation of Qsur is much larger than that of Qadv, while the interannual variabilities of Qsur and Qadv have the same magnitude. We investigate the roles of on different time scales. Qsur and Qadv for the temperature variations The study shows that the seasonal variation of temperature in the North Sea is determined by scale, Qsur. On interannual time scale, Qsur plays an important role on temperature variation in most parts of the North Sea. However, in the main pathways of the circulation in the North Sea, Qadv also plays a role on temperature interannual variability, especially in the northwest inflow region, where the North Atlantic water enters through Fair Isle Passage and from east of the Shetland.

Chen, Xinping; O'Driscoll, Kieran; Mayer, Bernhard; Su, Jian; Mathis, Moritz; Narayan, Nikesh; Pohlmann, Thomas

2013-04-01

354

Analysis of temperature variability and determination of apparent thermal diffusivity in sandy intertidal sediments at the German North Sea coast  

NASA Astrophysics Data System (ADS)

Temperature was measured at depths of 1, 10, 30, 75, and 170 cm in fine sandy intertidal sediments by means of specially-designed "temperature lances". The measurements cover a period from February to October 2007 and have a temporal resolution of 5 min. Stochastic as well as recurrent processes due to the solar cycle and due to tide induces flooding and drying of the sediment surface lead to a complex composition of the time series curves. Spectral analyses based on Fast Fourier Transformation (FFT) reveal that temperature variability at the sediment water/air interface is widely controlled by recurrent processes with period lengths of 4.93, 6.1, 8.19, ˜12, ˜24 h, and 354 h (14.7 days). The importance of the higher frequencies decreases with increasing sediment depth. At a depth of 30 cm the 24 h and the 14.7 days cycles mainly determine the temperature development over time, while at 75 cm sediment depth contour temperature varies only along the 14.7 days cycle, as well as within the seasonal cycle. Using cross-correlation-analysis the time necessary for a temperature signal at the surface to trigger a response at a sediment depth of 10, 30, and 75 cm was calculated as 1.4, 7.0, and 73.1 h respectively. Utilizing an alternate approach, FFT derived temperature peak-to-peak amplitude values and phase angles of up to 9 different cycles were used to calculate apparent thermal diffusivity in different sediment depths. The thermal diffusivity decreases from approximately 6-9 × 10-7 m2 s-1 from the surface down to a sediment depth of 75 cm. The specially-designed instrumentation has proven to be robust and precise enough to record high resolution time series of sediment temperature in different depths. The time series analysis of the data clearly shows that the temperature variability in the intertidal sediments to a high degree can be explained by recurrent solar and/or tidal effects. So the methods and results presented in this paper can help to answer questions, which are related to sediment temperature in tidal flat environments.

Ricklefs, Klaus; Vanselow, Klaus Heinrich

2012-08-01

355

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

356

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

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

Long term variability of the annual hydrological regime and sensitivity to temperature phase shifts in Saxony/Germany  

NASA Astrophysics Data System (ADS)

Recently, climatological studies report observational evidence of changes in the timing of the seasons, such as earlier timing of the annual cycle of surface temperature, earlier snow melt and earlier onset of the phenological spring season. Also hydrological studies report earlier timing and changes in monthly streamflows. From a water resources management perspective, there is a need to quantitatively describe the variability in the timing of hydrological regimes and to understand how climatic changes control the seasonal water budget of river basins. Here, the timing of hydrological regimes from 1930-2009 was investigated in a network of 27 river gauges in Saxony/Germany through a timing measure derived by harmonic function approximation of annual periods of runoff ratio series. The timing measure proofed to be robust and equally applicable to both mainly pluvial river basins and snow melt dominated regimes. We found that the timing of runoff ratio is highly variable, but markedly coherent across the basins analysed. Differences in average timing are largely explained by basin elevation. Also the magnitude of low frequent changes in the seasonal timing of streamflow and the sensitivity to the changes in the timing of temperature increase with basin elevation. This sensitivity is in turn related to snow storage and release, whereby snow cover dynamics in late winter explain a large part of the low- and high-frequency variability. A trend analysis based on cumulative anomalies revealed a common structural break around the year 1988. While the timing of temperature shifted earlier by 4 days, accompanied by a temperature increase of 1 K, the timing of runoff ratio within higher basins shifted towards occurring earlier about 1 to 3 weeks. This accelerated and distinct change indicates, that impacts of climate change on the water cycle may be strongest in higher, snow melt dominated basins.

Renner, M.; Bernhofer, C.

2011-06-01

359

The Surface Temperatures of the Earth: Steps towards Integrated Understanding of Variability and Change  

NASA Astrophysics Data System (ADS)

Surface temperature is a key aspect of weather and climate, relevant to human health, agriculture and leisure, ecosystem services, infrastructure development and economic activity. In a community-based activity, the EarthTemp Network brought together 55 researchers from 5 continents to improve the interaction between scientific communities who focus on particular domains, to exploit the strengths of different observing systems and to better meet the needs of different communities. The Network idenitified key needs for progress towards meeting societal needs for surface temperature understanding and information, which will be reviewed and discussed in this contribution. A "whole-Earth" perspective is required with more integrated, collaborative approaches to observing and understanding Earth's various surface temperatures. It is necessary to build understanding of the relationships of different surface temperatures, where presently inadequate, and undertake large-scale systematic intercomparisons. Datasets need to be easier to obtain and exploit for a wide constituency of users, with the differences and complementarities communicated in readily understood terms, and realistic and consistent uncertainty information. Steps are also recommended to curate and make available data that are presently inaccessible, develop new observing systems and build capacities to accelerate progress in the accuracy and usability of surface temperature datasets.

Matthiesen, Stephan; Merchant, Chris; Rayner, Nick; Remedios, John; Høyer, Jacob L.; Jones, Phil; Olesen, Folke; Roquet, Hervé; Sobrino, José; Thorne, Peter

2013-04-01

360

Blood acid-base state at a variable temperature. A graphical representation.  

PubMed

When blood temperature is changed in closed system ('anaerobic') conditions, plasma pH and PCO2 vary but no titration by external CO2, acid or alkaline equivalents takes place. It is therefore assumed that the overall acid-base state undergoes no fundamental change. This is further justified by the constancy of osmotic relationships between plasma and red cells, and to a lesser extent of relative alkalinity and protein alpha imidazole (Reeves, 1972, 1976a, b). These considerations serve as a basis for a correction procedure of pH and PCO2 of blood in open systems in vivo to a standard temperature T* (25 degrees C, eventually 37 degrees C). The temperature-corrected values pH* and P*CO2, and the derived [HCO3]* can be represented on a temperature-independent bicarbonate-pH diagram. This permits an easier interpretation of blood acid-base changes occurring together with body temperature variations, such as in ectotherms, hibernators or in artificial hypothermia. Extension to intracellular pH is considered. PMID:22117

Malan, A

1977-11-01

361

Low-frequency Sahel rainfall variability and Atlantic Sea Surface Temperatures during the last century  

NASA Astrophysics Data System (ADS)

This study revisits the question of the Atlantic SSTs-Sahel rainfall teleconnection variability along the 20th century using gridded data sets (SST, rainfall), selected Sahel rainfall time-series (Dakar in Senegal; Nioro du Sahel and Mopti in Mali; Niamey, Maradi and Maine-Soroa in Niger) and climate indices (AMO and TSA). In this study, we introduce a mixed time-series and spatial approach based on the spectral analysis (continuous wavelet transform and wavelet coherence and phase), which enables accurately assess the temporal, spatial and frequency non-stationarity of Atlantic SSTs-Sahel rainfall teleconnections. West African rainfalls show a pronounced negative trend over the Sahel since the late 1960s. Several dominant variability modes are observed according to the nearness of Atlantic Ocean. Three non-stationary areas of Sahel rainfall are thus revealed: Atlantic Coast (Dakar), Central Sahel (Nioro du Sahel and Mopti) and Eastern Sahel (Niamey, Maradi and Maine-Soroa). Previous hypothesis highlight the positive and negative weights of the North and (Tropical) South Atlantic SSTs respectively. Nevertheless, the statistical time-frequency study reveals an independent rainfall teleconnections with the North and (Tropical) South Atlantic SSTs. Increased rainfall over the Sahel is related to the positive phase of the AMO, due to a northward shift of the ITCZ. But behind 10°W-0°, the influence of North Atlantic SSTs variability is weak. In addition, as in the 50's the quasi-decadal teleconnections (9-19yrs) between Sahel rainfall and the North Atlantic SSTs can be associated with NAO patterns. A cold (warm) SSTs anomaly over the Tropical South Atlantic is associated with wet (dry) rainfall anomaly over the Sahel, and opposite anomaly over the Gulf of Guinea. But, this teleconnection is not geographically stable. Before 1970's, Western Sahel rainfall (including the coastal zone; Dakar, Nioro du Sahel, Mopti) appears to be statistically teleconnected with multi-decadal variability of South Atlantic SSTs. While since 1970's, Eastern Sahel rainfall (Niamey, Maradi, Maine-Soroa) appears to be teleconnected with quasi-decadal variability of Tropical South Atlantic SST. This study is focused on the Atlantic, but the longitudinal heterogeneity of Sahel rainfall is also dependent of land surfaces (albedo, vegetation cover and soil moisture) and the contrast between Indian and Atlantic SSTs, that modulating ascendance/subsidence in the east-west circulation. Nevertheless, over the 20th century, combinations of these various states of Atlantic SSTs explain a large part of annual Sahel rainfall amount fluctuations. The superposition of various teleconnections modulating an enhanced rainfall led to wet anomaly, and conversely for dry anomaly.

Dieppois, B.; Durand, A.; Fournier, M.; Diedhiou, A.; Fontaine, B.; Massei, N.; Nouaceur, Z.; Sebag, D.

2012-04-01

362

Comparison of Variability of the Monthly Mean Temperature of the ECMWF and NCEP Reanalyses and CCM3 and DSM Simulations  

SciTech Connect

The low frequency variation in the three dimensional air temperature fields of two reanalyses and two model simulations are described. The data sets used are the monthly mean temperature fields for the NCAR Climate Simulation Model (CSM, Boville and Gent, 1998) 300 year run, a NCAR Community Climate Model version 3 (CCM3, Kiehl et al., 1998) AMIP type simulation, and the NCEPLNCAR and ECMWF (ERA) reanalysis data sets. The variances and correlations are computed for the anomalies from the annual cycle for each data set. In general the reanalyses and models agree fairly well on the structure of the temperature variance. The models tend to have too much variance at the surface compared to the reanalyses. The CSM's poor simulation of the SST in the eastern Pacific leads to a much reduced variance in the Nino3 region. The enhanced variability over land appears to affect the midlatitude simulation of the CSM in that the higher surface variability extends off the east coast of continents. This is not evident in CCM3 and reanalyses where the SSTs are prescribed. At 200 hPa the CCM3 and reanalyses all evince the dumb bell pattern straddling the Equator in the eastern Pacific attributed by Yulaeva and Wallace (1994) to ENS0 variations. The CSM shows no such pattern. A CCM3 integration using climatological SSTs displays more variance that the CSM in this region, apparently the CSM suppresses variability in this locale. The correlations of the temperature fields with the surface air temperature show that the regions of subtropical subsidence are virtually uncorrelated to the surface at the 700 hPa level. The regions of the cold water off the west coast of continents evince decoupling with the surface at 850 hPa. In the region from 30s to 30N the zonal mean correlation falls to about 0.7 below 800 hPa, with this value extending up to about 600 hPa in mid and upper latitudes. These characteristics are consistent across all the data sets. Thus, the variations of vertically integrated measures such as MSU temperatures do not need agree with observations of surface air temperatures at the time scales examined here.

Boyle, J.S.

2000-02-16

363

Comparison of Variability of the Monthly Mean Temperature of the ECMWF and NCEP Reanalyses and CCM3 and CSM Simulations  

SciTech Connect

The low frequency variation in the three dimensional air temperature fields of two reanalyses and two model simulations are described. The data sets used are the monthly mean temperature fields for the NCAR Climate Simulation Model (CSM, Boville and Gent, 1998) 300 year run, a NCAR Community Climate Model version 3 (CCM3, Kiehl et al., 1998) AMIP type simulation, and the NCEP/NCAR and ECMWF (ERA) reanalysis data sets. The variances and correlations are computed for the anomalies from the annual cycle for each data set. In general the reanalyses and models agree fairly well on the structure of the temperature variance. The models tend to have too much variance at the surface compared to the reanalyses. The CSMs poor simulation of the SST in the eastern Pacific leads to a much reduced variance in the Nino3 region. The enhanced variability over land appears to affect the midlatitude simulation of the CSM in that the higher surface variability extends off the east coast of continents. This is not evident in CCM3 and reanalyses where the SSTs are prescribed. At 200 hPa the CCM3 and reanalyses all evince the dumb bell pattern straddling the Equator in the eastern Pacific attributed by Yulaeva and Wallace (1994) to ENSO variations. The CSM shows no such pattern. A CCM3 integration using climatological SSTs displays more variance that the CSM in this region. Apparently the coupling to an ocean in the CSM suppresses the atmospheric model's variability in this locale. The correlations of the temperature fields with the surface air temperature show that the regions of subtropical subsidence are virtually uncorrelated to the surface at the 700 hPa level. The regions of the cold water off the west coast of continents evince decoupling with the surface at 850 hPa. In the region from 30S to 30N the zonal mean correlation falls to about 0.7 below 800 hPa, with this value extending up to about 600 hPa in mid and upper latitudes. These characteristics are consistent across all the data sets. Thus, the variations of vertically integrated measures such as MSU temperatures need not agree with observations of surface air temperatures at the time scales examined here.

Boyle, J.

2000-03-01

364

Variable temperature and ex situ spin-polarized low-energy electron microscope  

SciTech Connect

The spin-polarized low-energy electron microscope (SPLEEM) at NCEM has been utilized to examine the magnetic domain formation in thin films of Co grown on Au(111) single-crystal surfaces. A new, low-temperature liquid nitrogen cooling system has been added to this instrument, achieving sample temperatures over a wide range (115-2300 K) and enabling the first SPLEEM images to be obtained at below room temperature. Furthermore, the deposition of protective, nonmagnetic capping layers on top of the Co/Au(111) surface is observed to have little effect on the domain shape except for decreasing magnetic contrast due to the attenuation of the diffracted electrons from the Co layer. The magnetic domain contrast is nearly completely restored upon thinning the capping layers by ion bombardment enabling the examination of ex situ prepared samples. (c) 2000 American Vacuum Society.

Tober, E. D. [National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)] [National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Witte, G. [National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)] [National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Poppa, H. [National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)] [National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

2000-07-01

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

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

367

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

368

The Spatial Variations of Urban Land Surface Temperatures: Pertinent Factors, Zoning Effect, and Seasonal Variability  

Microsoft Academic Search

Remote sensing of urban land surface temperatures (LSTs) has been conducted based largely on pixel-by-pixel correlation with land use and land cover (LULC) types. Few studies have examined the spatial variations of LST within land use zoning polygons, in spite of its significance on the knowledge of environmental implications or planning practices. This study aimed to analyze the spatial patterns

Qihao Weng; Hua Liu; Bingqing Liang; Dengsheng Lu

2008-01-01

369

Influence of Modes of Climate Variability on Global Temperature Extremes JESSE KENYON  

E-print Network

difficult to diagnose and understand than changes in mean climate. Apart from the greater statistical for temperature extremes from world- wide land areas are used describe moderate extremes, such as the number of climate phenomena, yet comprise large enough samples to diagnose and de- tect changes, resulted

370

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

E-print Network

Relationships between Pacific and Atlantic ocean sea surface temperatures and U.S. streamflow March 2006; published 19 July 2006. [1] An evaluation of Pacific and Atlantic Ocean sea surface by an interdecadal-temporal evaluation for the Pacific (Atlantic) Ocean based on the phase of the Pacific Decadal

Piechota, Thomas C.

371

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

372

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

373

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

374

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

375

An analysis of seasonal variability of satellite detected land surface temperatures and urban heat islands  

Microsoft Academic Search

This research intends to develop a diffusive UHI model and to compare it with UHIs based on impervious coverage as well as those based on population distribution using Indianapolis as a case study Land surface temperatures LSTs in the four seasons were extracted from thermal infrared data of Terra s ASTER imagery and calibrated with emissivity and other parameters Heat

Q. Weng

2006-01-01

376

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

377

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

Microsoft Academic Search

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

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

2005-01-01

378

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

379

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

380

A Bayesian partition modelling approach to resolve spatial variability in climate records from borehole temperature inversion  

NASA Astrophysics Data System (ADS)

Collections of suitably chosen borehole profiles can be used to infer large-scale trends in ground-surface temperature (GST) histories for the past few hundred years. These reconstructions are based on a large database of carefully selected borehole temperature measurements from around the globe. Since non-climatic thermal influences are difficult to identify, representative temperature histories are derived by averaging individual reconstructions to minimize the influence of these perturbing factors. This may lead to three potentially important drawbacks: the net signal of non-climatic factors may not be zero, meaning that the average does not reflect the best estimate of past climate; the averaging over large areas restricts the useful amount of more local climate change information available; and the inversion methods used to reconstruct the past temperatures at each site must be mathematically identical and are therefore not necessarily best suited to all data sets. In this work, we avoid these issues by using a Bayesian partition model (BPM), which is computed using a trans-dimensional form of a Markov chain Monte Carlo algorithm. This then allows the number and spatial distribution of different GST histories to be inferred from a given set of borehole data by partitioning the geographical area into discrete partitions. Profiles that are heavily influenced by non-climatic factors will be partitioned separately. Conversely, profiles with climatic information, which is consistent with neighbouring profiles, will then be inferred to lie in the same partition. The geographical extent of these partitions then leads to information on the regional extent of the climatic signal. In this study, three case studies are described using synthetic and real data. The first demonstrates that the Bayesian partition model method is able to correctly partition a suite of synthetic profiles according to the inferred GST history. In the second, more realistic case, a series of temperature profiles are calculated using surface air temperatures of a global climate model simulation. In the final case, 23 real boreholes from the United Kingdom, previously used for climatic reconstructions, are examined and the results compared with a local instrumental temperature series and the previous estimate derived from the same borehole data. The results indicate that the majority (17) of the 23 boreholes are unsuitable for climatic reconstruction purposes, at least without including other thermal processes in the forward model.

Hopcroft, Peter O.; Gallagher, Kerry; Pain, Christopher C.

2009-08-01

381

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

382

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

NASA Astrophysics Data System (ADS)

mesospheric clouds (PMCs) measured by the Cloud Imaging and Particle Size instrument on the AIM satellite show strong zonal asymmetries, with prominent planetary-scale variations. The correlations between zonal variations of cloud brightness and temperature or water vapor (H2O) are determined in different stages of the PMC season. Aura Microwave Limb Sounder measured temperature and water vapor are used in the analysis. A zero-dimensional (0-D) PMC model was used to interpret the observation. Analyses of all days of the five northern seasons from 2007 to 2011 indicate that temperature and albedo daily zonal variations are anticorrelated in the season start and end, whereas in the core of the season the correlation is relatively poor. The albedo and H2O correlation in the zonal direction is poor throughout the season. Zero-dimensional model physics indicates that when clouds are weaker, or the environment is warmer and drier, temperature plays an increasingly important role in determining the cloud ice mass variation, which explains the stronger correlation of temperature and albedo at the start and end of the season. Water vapor takes a strong role in determining the ice mass variation in the core of the season when the clouds are stronger and the environment is colder and wetter. However, on a daily basis the H2O depletion associated with the ice production will lead to significant shift of the ice maxima and "post-ice" H2O maxima in the zonal direction, which leads to the poor correlation between the observed H2O and albedo.

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

2014-03-01

383

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

384

Control of supply air temperature and outdoor airflow and its effect on energy use in a variable air volume system  

SciTech Connect

A VAV system in a commercial office building in central New Jersey has been modeled, with DOE-2 and a variable-base bin method, to assess control strategies that lead to reduce HVAC costs with no decrease in comfort. The goal is to minimize the sum of fan and heating/cooling power while providing sufficient air to maintain desired office temperatures and air quality. With the 55 F (12.8/sup 0/C) supply air temperature specified by the HVAC designer, fan energy is kept low at the expense of the chillers. Raising the supply air temperature to 60 F (15.6/sup 0/C) makes more use of outdoor air in temperate weather and reduces the chiller energy consumption by a predicted 33 MWh/year while increasing fan power by only 4 MWh, for a net savings in combined fan and chiller power of 23%. An additional 9 MWh of net fan and chiller energy savings can be achieved by varying the supply air temperature with outdoor temperature.

Norford, L.K.; Rabi, A.; Socolow, R.H.

1986-01-01

385

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

386

Variable low-temperature scanning tunneling microscopy study of Si(001): Nature of the 2 1~c(2 4) phase transition  

E-print Network

at around 200 K.9 The first low-temperature LT STM images of this surface showed that at LTs the surface of this phase transition should explain why the surface at low temperature exhibits prima- rily c 2 4 ratherVariable low-temperature scanning tunneling microscopy study of Si(001): Nature of the 2 1~c(2 4

387

Temperature variability over the Po Valley, Italy, according to radiosounding data  

E-print Network

Temperature variations registered above the southeast part of the Po Valley, Italy have been examined by applying the principal component analysis of radiosoung profiles recorded during the period from 1987 to 2010. Two data sets, considered to describe intra- and inter-annual oscillations, respectively were extracted from the measurements data and the results show that both types of fluctuations can be projected onto four empirical orthogonal functions (EOF), interpreted as vertical distributions of oscillation amplitudes and four uncorrelated time series that represent the evolution of corresponding EOFs. It was found that intra-annual oscillations composed of periods between 30 and 120 days, together with inter-annual variations of 1- to 7-year period contribute to the highest extent (about 70 percents) the temperature oscillations up to 20 km, changing in both cases the phase in the tropopausal region. The other three EOFs indicate prevailing weight of the oscillations in the upper troposphere-low stratos...

Petkov, Boyan Hristozov

2014-01-01

388

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

389

Biodegradation of variable-chain-length alkanes at low temperatures by a psychrotrophic Rhodococcus sp  

Microsoft Academic Search

The psychrotroph Rhodococcus sp. strain Q15 was examined for its ability to degrade individual n-alkanes and diesel fuel at low temperatures, and its alkane catabolic pathway was investigated by biochemical and genetic techniques. At 0 and 5 C, Q15 mineralized the short-chain alkanes dodecane and hexadecane to a greater extent than that observed for the long-chain alkanes octacosane and dotriacontane.

LYLE G. WHYTE; JALAL HAWARI; EDWARD ZHOU; LUC BOURBONNIERE; C. W. Greer; W. E. Inniss

1998-01-01

390

Arctic climate change: observed and modelled temperature and sea-ice variability  

Microsoft Academic Search

Changes apparent in the arctic climate system in recent years require evaluation in a century-scale perspective in order to assess the Arctic's response to increasing anthropogenic greenhouse-gas forcing. Here, a new set of century- and multidecadal-scale observational data of surface air temperature (SAT) and sea ice is used in combination with ECHAM4 and HadCM3 coupled atmosphere ice ocean global model

Ola M. Johannessen; Lennart Bengtsson; Martin W. Miles; Svetlana I. Kuzmina; Vladimir A. Semenov; Genrikh V. Alekseev; Andrei P. Nagurnyi; Victor F. Zakharov; Leonid P. Bobylev; Lasse H. Pettersson; Klaus Hasselmann; Howard P. Cattle

2004-01-01

391

Effect of Variable Graphitic and Diamond-Like Content on the Temperature of Carbonaceous Dust  

Microsoft Academic Search

The equilibrium temperature of composite carbon grains is shown to be a sensitive function of the ratio of aromatic (sp2) to diamond (sp3) bonded carbon in the grain. Calculations have been carried out for grains with radii 0.001 < a < 0.1 iim and compositions that consist of niixtures of aromatic carbon, diamond-like carbon, polymeric carbon and voids. An effective

G. P. Pinho; W. W. Duley

1994-01-01

392

Jovian temperature and cloud variability during the 2009–2010 fade of the South Equatorial Belt  

Microsoft Academic Search

Mid-infrared 7–20?m imaging of Jupiter from ESO’s Very Large Telescope (VLT\\/VISIR) demonstrate that the increased albedo of Jupiter’s South Equatorial Belt (SEB) during the ‘fade’ (whitening) event of 2009–2010 was correlated with changes to atmospheric temperature and aerosol opacity. The opacity of the tropospheric condensation cloud deck at pressures less than 800mbar increased by 80% between May 2008 and July

Leigh N. Fletcher; G. S. Orton; J. H. Rogers; A. A. Simon-Miller; I. de Pater; M. H. Wong; O. Mousis; P. G. J. Irwin; M. Jacquesson; P. A. Yanamandra-Fisher

2011-01-01

393

Sea Ice and Ice Temperature Variability as Observed by Microwave and Infrared Satellite Data  

NASA Technical Reports Server (NTRS)

Recent reports of a retreating and thinning sea ice cover in the Arctic have pointed to a strong suggestion of significant warming in the polar regions. It is especially important to understand what these reports mean in light of the observed global warning and because the polar regions are expected to be most sensitive to changes in climate. To gain insight into this phenomenon, co-registered ice concentrations and surface temperatures derived from two decades of satellite microwave and infrared data have been processed and analyzed. While observations from meteorological stations indicate consistent surface warming in both regions during the last fifty years, the last 20 years of the same data set show warming in the Arctic but a slight cooling in the Antarctic. These results are consistent with the retreat in the Arctic ice cover and the advance in the Antarctic ice cover as revealed by historical satellite passive microwave data. Surface temperatures derived from satellite infrared data are shown to be consistent within 3 K with surface temperature data from the limited number of stations. While not as accurate, the former provides spatially detailed changes over the twenty year period. In the Arctic, for example, much of the warming occurred in the Beaufort Sea and the North American region in 1998 while slight cooling actually happened in parts of the Laptev Sea and Northern Siberia during the same time period. Big warming anomalies are also observed during the last five years but a periodic cycle of about ten years is apparent suggesting a possible influence of the North Atlantic Oscillation. In the Antarctic, large interannual and seasonal changes are also observed in the circumpolar ice cover with regional changes showing good coherence with surface temperature anomalies. However, a mode 3 is observed to be more dominant than the mode 2 wave reported in the literature. Some of these spatial and temporal changes appear to be influenced by the Antarctic Circumpolar Wave (ACW) and changes in coastal polynya activities.

Comiso, Josefino C.; Koblinsky, Chester J. (Technical Monitor)

2001-01-01

394

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

Microsoft Academic Search

BackgroundSyncope 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

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

2011-01-01

395

Seasonal and interannual variability in temperature, chlorophyll and macronutrients in northern Marguerite Bay, Antarctica  

Microsoft Academic Search

We report data from the first 8 years of oceanographic monitoring in Ryder Bay, northern Marguerite Bay, Antarctica. These data form the oceanographic component of the Rothera Oceanographic and Biological Time-Series (RaTS) project. When weather and ice permit, the RaTS station is occupied every 5 days in summer and weekly in winter. Observations comprise a conductivity–temperature–depth (CTD) cast to 500m

Andrew Clarke; Michael P. Meredith; Margaret I. Wallace; Mark A. Brandon; David N. Thomas

2008-01-01

396

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

397

Holocene sea-surface temperature variability in the Chilean fjord region  

NASA Astrophysics Data System (ADS)

Here we provide three new Holocene (11-0 cal ka BP) alkenone-derived sea surface temperature (SST) records from the southernmost Chilean fjord region (50-53°S). SST estimates may be biased towards summer temperature in this region, as revealed by a large set of surface sediments. The Holocene records show consistently warmer than present-day SSTs except for the past ~ 0.6 cal ka BP. However, they do not exhibit an early Holocene temperature optimum as registered further north off Chile and in Antarctica. This may have resulted from a combination of factors including decreased inflow of warmer open marine waters due to lower sea-level stands, enhanced advection of colder and fresher inner fjord waters, and stronger westerly winds. During the mid-Holocene, pronounced short-term variations of up to 2.5°C and a cooling centered at ~ 5 cal ka BP, which coincides with the first Neoglacial glacier advance in the Southern Andes, are recorded. The latest Holocene is characterized by two pronounced cold events centered at ~ 0.6 and 0.25 cal ka BP, i.e., during the Little Ice Age. These cold events have lower amplitudes in the offshore records, suggesting an amplification of the SST signal in the inner fjords.

Caniupán, Magaly; Lamy, Frank; Lange, Carina B.; Kaiser, Jérôme; Kilian, Rolf; Arz, Helge W.; León, Tania; Mollenhauer, Gesine; Sandoval, Susana; De Pol-Holz, Ricardo; Pantoja, Silvio; Wellner, Julia; Tiedemann, Ralf

2014-09-01

398

Trap density of states in n-channel organic transistors: variable temperature characteristics and band transport  

NASA Astrophysics Data System (ADS)

We have investigated trap density of states (trap DOS) in n-channel organic field-effect transistors based on N,N '-bis(cyclohexyl)naphthalene diimide (Cy-NDI) and dimethyldicyanoquinonediimine (DMDCNQI). A new method is proposed to extract trap DOS from the Arrhenius plot of the temperature-dependent transconductance. Double exponential trap DOS are observed, in which Cy-NDI has considerable deep states, by contrast, DMDCNQI has substantial tail states. In addition, numerical simulation of the transistor characteristics has been conducted by assuming an exponential trap distribution and the interface approximation. Temperature dependence of transfer characteristics are well reproduced only using several parameters, and the trap DOS obtained from the simulated characteristics are in good agreement with the assumed trap DOS, indicating that our analysis is self-consistent. Although the experimentally obtained Meyer-Neldel temperature is related to the trap distribution width, the simulation satisfies the Meyer-Neldel rule only very phenomenologically. The simulation also reveals that the subthreshold swing is not always a good indicator of the total trap amount, because it also largely depends on the trap distribution width. Finally, band transport is explored from the simulation having a small number of traps. A crossing point of the transfer curves and negative activation energy above a certain gate voltage are observed in the simulated characteristics, where the critical VG above which band transport is realized is determined by the sum of the trapped and free charge states below the conduction band edge.

Cho, Joung-min; Akiyama, Yuto; Kakinuma, Tomoyuki; Mori, Takehiko

2013-10-01

399

Trap density of states in n-channel organic transistors: variable temperature characteristics and band transport  

SciTech Connect

We have investigated trap density of states (trap DOS) in n-channel organic field-effect transistors based on N,N?’-bis(cyclohexyl)naphthalene diimide (Cy-NDI) and dimethyldicyanoquinonediimine (DMDCNQI). A new method is proposed to extract trap DOS from the Arrhenius plot of the temperature-dependent transconductance. Double exponential trap DOS are observed, in which Cy-NDI has considerable deep states, by contrast, DMDCNQI has substantial tail states. In addition, numerical simulation of the transistor characteristics has been conducted by assuming an exponential trap distribution and the interface approximation. Temperature dependence of transfer characteristics are well reproduced only using several parameters, and the trap DOS obtained from the simulated characteristics are in good agreement with the assumed trap DOS, indicating that our analysis is self-consistent. Although the experimentally obtained Meyer-Neldel temperature is related to the trap distribution width, the simulation satisfies the Meyer-Neldel rule only very phenomenologically. The simulation also reveals that the subthreshold swing is not always a good indicator of the total trap amount, because it also largely depends on the trap distribution width. Finally, band transport is explored from the simulation having a small number of traps. A crossing point of the transfer curves and negative activation energy above a certain gate voltage are observed in the simulated characteristics, where the critical V{sub G} above which band transport is realized is determined by the sum of the trapped and free charge states below the conduction band edge.

Cho, Joung-min, E-mail: cho.j.ad@m.titech.ac.jp; Akiyama, Yuto; Kakinuma, Tomoyuki [Department of Organic and Polymeric Materials, Tokyo Institute of Technology, O-okayama, Tokyo 152-8552 (Japan)] [Department of Organic and Polymeric Materials, Tokyo Institute of Technology, O-okayama, Tokyo 152-8552 (Japan); Mori, Takehiko [Department of Organic and Polymeric Materials, Tokyo Institute of Technology, O-okayama, Tokyo 152-8552 (Japan) [Department of Organic and Polymeric Materials, Tokyo Institute of Technology, O-okayama, Tokyo 152-8552 (Japan); ACT-C, JST, Honcho, Kawaguchi, Saitama 332-0012 (Japan)

2013-10-15

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Variability and trends in dynamical forcing of tropical lower stratospheric temperatures  

NASA Astrophysics Data System (ADS)

We analyse the relation between tropical lower stratospheric temperatures and dynamical forcing over the period 1980-2011 using NCEP, MERRA and ERA-Interim reanalyses. The tro