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1

Propagation of linear surface air temperature trends into the terrestrial subsurface  

E-print Network

Propagation of linear surface air temperature trends into the terrestrial subsurface Marielle air and terrestrial subsurface temperatures working under the assumption that linear trends in surface robust estimates of multidecadal to centennial temperature changes at the Earth's surface for several hun

Beltrami, Hugo

2

Linear trends in Northern Hemisphere tropospheric geopotential height and temperature patterns  

NASA Technical Reports Server (NTRS)

Gridded National Meteorological Center data for 500 mb geopotential height and 300-500 mb and 500-700 mb thickness for the period 1951-1978 are subjected to linear trend analyses. The analyses are carried out for each calendar month. Significant geographical and seasonal distributions of cooling and warming patterns are found. An atmospheric cooling trend over the North Pacific during the winter months is seen in a region where oceanic cooling has also been observed, but planetary-wave adjustments rather than ocean-atmosphere feedback mechanisms appear to be dominant in the atmospheric cooling on climatic time scales. Consistently large temperature trends are also seen over the continent of Asia. Comparisons between thickness trends in the layer 300-500 mb and those in the layer 500-700 mb reveal pronounced patterns of stabilization and destabilization.

Reiter, E. R.; Westhoff, D. R.

1982-01-01

3

Temperature trends in the midlatitude summer mesosphere  

NASA Astrophysics Data System (ADS)

We have performed trend studies in the mesosphere in the period 1961-2009 with Leibniz-Institute Middle Atmosphere (LIMA) model driven by European Centre for Medium-Range Weather Forecasts reanalysis below approximately 40 km and adapts temporal variations of CO2 and O3 according to observations. Temperatures in the mesosphere/lower thermosphere vary nonuniformly with time, mainly due to the influence of O3. Here we analyze the contribution of varying concentrations of CO2 and O3 to the temperature trend in the mesosphere. It is important to distinguish between trends on pressure altitudes, zp, and geometrical altitudes, zgeo, where the latter includes the effect of shrinking due to cooling at lower heights. For the period 1961-2009, temperature trends on geometrical and pressure altitudes can differ by as much as -0.9 K/dec in the mesosphere. Temperature trends reach approximately -1.3±0.11 K/dec at zp˜60 km and -1.8±0.18 K/dec at zgeo˜70 km, respectively. CO2 is the main driver of these trends in the mesosphere, whereas O3 contributes approximately one third, both on geometrical and pressure heights. Depending on the time period chosen, linear temperature trends can vary substantially. Altitudes of pressure levels in the mesosphere decrease by up to several hundred meters. We have performed long-term runs with LIMA applying twentieth century reanalysis dating back to 1871. Again, trends are nonuniform with time. Since the late nineteenth century, temperatures in the mesosphere have dropped by approximately 5-7 K on pressure altitudes and up to 10-12 K on geometrical altitudes.

Lübken, F.-J.; Berger, U.; Baumgarten, G.

2013-12-01

4

Long-term trends in Antarctic winter hydroxyl temperatures  

Microsoft Academic Search

Fifteen year observational record of hydroxyl temperatures in AntarcticaMeasurement of solar cycle response and long-term linear trendExamination of the influence of planetary waves and other dynamical indices

W. John R. French; A. R. Klekociuk

2011-01-01

5

Estimating population trends with a linear model  

USGS Publications Warehouse

We describe a simple and robust method for estimating trends in population size. The method may be used with Breeding Bird Survey data, aerial surveys, point counts, or any other program of repeated surveys at permanent locations. Surveys need not be made at each location during each survey period. The method differs from most existing methods in being design based, rather than model based. The only assumptions are that the nominal sampling plan is followed and that sample size is large enough for use of the t-distribution. Simulations based on two bird data sets from natural populations showed that the point estimate produced by the linear model was essentially unbiased even when counts varied substantially and 25% of the complete data set was missing. The estimating-equation approach, often used to analyze Breeding Bird Survey data, performed similarly on one data set but had substantial bias on the second data set, in which counts were highly variable. The advantages of the linear model are its simplicity, flexibility, and that it is self-weighting. A user-friendly computer program to carry out the calculations is available from the senior author.

Bart, J.; Collins, B.; Morrison, R.I.G.

2003-01-01

6

Linear trends of temperature at intermediate and deep layers of the North Atlantic and the North Pacific Oceans: 1957-1981  

SciTech Connect

Using all available hydrographic station data on ocean temperature observations from World Data Center-B (Obninsk, Russia), investigation of temperature changes in the North Atlantic and North Pacific oceans within the depth range of 300 to 3,000 m has been carried out for the period 1957--1981. Results of statistical data analysis show that in the upper layer to about 500-m depths of both oceans, on average, seawater temperature declined. Deeper than 500--600 m in the North Pacific Ocean, no significant temperature changes have been revealed for this 25-year time interval. On average, for the North Atlantic Ocean, a statistically significant temperature rise (about 0.1[degrees]C 25 yr[sup [minus]1]) is observed in the 800- to 2,500-m layer. 28 refs., 20 figs., 2 tab.

Antonov, J.I. (State Hydrological Institute, St. Petersburg (Russian Federation))

1993-10-01

7

Twentieth-century sea surface temperature trends  

Microsoft Academic Search

An analysis of historical sea surface temperatures provides evidence for global warming since 1900, in line with land-based analyses of global temperature trends, and also shows that over the same period, the eastern equatorial Pacific cooled and the zonal sea surface temperature gradient strengthened. Recent theoretical studies have predicted such a pattern as a response of the coupled ocean-atmosphere system

M. A. Cane; A. C. Clement; A. Kaplan

1997-01-01

8

Comparison between global and regional temperature trends  

SciTech Connect

Variability of the annual temperature data during the last 100 years is analyzed. The basic data consist of annual temperature for 15 stations located in the flat country part of Bulgaria. Data from Warsaw (Poland), Bucharest (Romania), and Thessalonike (Greece) are analyzed, too. Also the annual air temperature for the Northern Hemisphere, computed by Jones and Wigley, by Hansen, Wilson, and Ruedy, and by Vinnikov, Groisman, and Lugina, are used. The temperature series are smoothed by 10-year weighted moving average and fitted by 7-order polynomial. The presence of some form of trend in the temperature time series is examined by Spearman and Mann-Kendall rank statistics. The power spectrum analysis is applied, too. In general, the trend is positive in North Bulgaria (NB) and negative in South Bulgaria (SB). In Warsaw and Thessalonike the air temperature shows a decreasing trend, while in Bucharest it increases.

Koleva, E.; Yotova, A. [National Inst. of Meteorology and Hydrology, Sofia (Bulgaria)

1994-12-31

9

Temperature analysis over southwest Iran: trends and projections  

NASA Astrophysics Data System (ADS)

The present study intends to show the effect of climate change on trends and patterns of temperature over the southwestern part of Iran. The research has been divided into two parts. The first part consists of an analysis of the temperature trends of mean temperature (TM), maximum temperature (TMAX), and minimum temperature (TMIN) over 39 stations in the study region for the period 1950-2007. The trends in these parameters were detected by linear regression, and significance was tested by t test. Mann-Kendall rank test (MK test) was also employed to confirm the results. The second part of the research involved future projection of temperature based on four models. The models used were Centre National de Recherches Meteorologiques, European Center Hamburg Model, Model for Interdisciplinary Research on Climate, and UK Meteorological Office. Temperature projections were done under B1 and A1B emissions scenarios. The analysis of temperature trends revealed a significant increase during summer and spring seasons. TMAX was stable than TMIN and TM, and winter was stable as compared with summer, spring, and autumn seasons. Results of modeling showed that temperature may increase between 1.69 and 6.88 °C by 2100 in the study area. Summer temperatures may increase with higher rates than spring, winter, and autumn temperatures.

Zarenistanak, Mohammad; Dhorde, Amit G.; Kripalani, R. H.

2014-04-01

10

Stratospheric temperature trends: Observations and model simulations  

Microsoft Academic Search

Trends and variations in global stratospheric temperatures are an integral part of the changes occurring in the Earth's climate system. Data sets for analyzing long-term (a decade and more) changes in the stratospheric temperatures consist of radiosonde, satellite, lidar, and rocketsonde measurements; meteorological analyses based on radiosonde and\\/or satellite data; and products based on assimilating observations using a general circulation

V. Ramaswamy; M.-L. Chanin; J. Angell; J. Barnett; D. Gaffen; M. Gelman; P. Keckhut; Y. Koshelkov; K. Labitzke; J.-J. R. Lin; A. O'Neill; J. Nash; W. Randel; R. Rood; K. Shine; M. Shiotani; R. Swinbank

2001-01-01

11

Temperature trends in the lower mesosphere  

Microsoft Academic Search

The largest atmospheric temperature changes due to the increase of greenhouse gases are expected in the 40 to 60 km altitude region, where enhanced infrared cooling decreases the temperature. Ten-year (1980-1990) temperature trends at 55 km and 0.4 mb, derived using data from the ground-based lidar at Haute Provence, 44°N 6°E, and the SSU channel 47X on several satellites, are

A. C. Aikin; M. L. Chanin; J. Nash; D. J. Kendig

1991-01-01

12

Condensation temperature trends among stars with planets  

E-print Network

Results from detailed spectroscopic analyses of stars hosting massive planets are employed to search for trends between abundances and condensation temperatures. The elements C, S, Na, Mg, Al, Ca, Sc, Ti, V, Cr, Mn, Fe, Ni and Zn are included in the analysis of 64 stars with planets and 33 comparison stars. No significant trends are evident in the data. This null result suggests that accretion of rocky material onto the photospheres of stars with planets is not the primary explanation for their high metallicities. However, the differences between the solar photospheric and meteoritic abundances do display a weak but significant trend with condensation temperature. This suggests that the metallicity of the sun's envelope has been enriched relative to its interior by about 0.07 dex.

Guillermo Gonzalez

2005-12-08

13

An update of observed stratospheric temperature trends  

Microsoft Academic Search

An updated analysis of observed stratospheric temperature variability and trends is presented on the basis of satellite, radiosonde, and lidar observations. Satellite data include measurements from the series of NOAA operational instruments, including the Microwave Sounding Unit covering 1979-2007 and the Stratospheric Sounding Unit (SSU) covering 1979-2005. Radiosonde results are compared for six different data sets, incorporating a variety of

William J. Randel; Keith P. Shine; John Austin; John Barnett; Chantal Claud; Nathan P. Gillett; Philippe Keckhut; Ulrike Langematz; Roger Lin; Craig Long; Carl Mears; Alvin Miller; John Nash; Dian J. Seidel; David W. J. Thompson; Fei Wu; Shigeo Yoden

2009-01-01

14

20-Year Arctic Surface Temperature Trend  

NSDL National Science Digital Library

Here the 20-year surface temperature trend is shown over the Arctic region. This animation shows the warming and cooling regions in steps from the regions of least change to the areas of greatest change. Blue hues indicate cooling regions; red hues depict warming. Light regions indicate less change while darker regions indicate more. The temperature scale used ranges from -0.4 to +0.4 degrees Celsius in increments of .02 degrees. (See color bar below)

Starr, Cindy; Comiso, Josefino

2003-10-23

15

22-Year Arctic Surface Temperature Trend  

NSDL National Science Digital Library

This image shows the 22-year surface temperature trend over the Arctic region. Blue hues indicate areas that are cooling; gold hues depict areas that are warming. Lighter colors indicate less change while darker colors indicate more. The temperature scale steps from zero degrees Celsius in increments of .02 degrees. (See color bar below) The data ranges from -0.162 to +0.487 degrees Celsius.

Starr, Cindy; Comiso, Josefino

2004-12-13

16

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

17

Global trends of measured surface air temperature  

NASA Technical Reports Server (NTRS)

The paper presents the results of surface air temperature measurements from available meteorological stations for the period of 1880-1985. It is shown that the network of meteorological stations is sufficient to yield reliable long-term, decadal, and interannual temperature changes for both the Northern Hemisphere and the Southern Hemisphere, despite the fact that most stations are located on the continents. The results indicate a global warming of about 0.5-0.7 C in the past century, with warming of similar magnitude in both hemispheres. A strong warming trend between 1965 and 1980 raised the global mean temperature in 1980 and 1981 to the highest level in the period of instrumental records. Selected graphs of the temperature change in each of the eight latitude zones are included.

Hansen, James; Lebedeff, Sergej

1987-01-01

18

Statistical significance of trends and trend differences in layer-average atmospheric temperature time series  

Microsoft Academic Search

This paper examines trend uncertainties in layer-average free atmosphere temperatures arising from the use of different trend estimation methods. It also considers statistical issues that arise in assessing the significance of individual trends and of trend differences between data sets. Possible causes of these trends are not addressed. We use data from satellite and radiosonde measurements and from two reanalysis

B. D. Santer; T. M. L. Wigley; J. S. Boyle; D. J. Gaffen; J. J. Hnilo; D. Nychka; D. E. Parker; K. E. Taylor

1999-01-01

19

Disparity of tropospheric and surface temperature trends: New evidence  

E-print Network

Disparity of tropospheric and surface temperature trends: New evidence David H. Douglass,1 Benjamin surface temperatures, we suggest that the disparity is probably associated with processes at the ocean (2004), Disparity of tropospheric and surface temperature trends: New evidence, Geophys. Res. Lett., 31

Douglass, David H.

20

Evolution of land surface air temperature trend  

NASA Astrophysics Data System (ADS)

The global climate has been experiencing significant warming at an unprecedented pace in the past century. This warming is spatially and temporally non-uniform, and one needs to understand its evolution to better evaluate its potential societal and economic impact. Here, the evolution of global land surface air temperature trend in the past century is diagnosed using the spatial-temporally multidimensional ensemble empirical mode decomposition method. We find that the noticeable warming (>0.5 K) started sporadically over the global land and accelerated until around 1980. Both the warming rate and spatial structure have changed little since. The fastest warming in recent decades (>0.4 K per decade) occurred in northern mid-latitudes. From a zonal average perspective, noticeable warming (>0.2 K since 1900) first took place in the subtropical and subpolar regions of the Northern Hemisphere, followed by subtropical warming in the Southern Hemisphere. The two bands of warming in the Northern Hemisphere expanded from 1950 to 1985 and merged to cover the entire Northern Hemisphere.

Ji, Fei; Wu, Zhaohua; Huang, Jianping; Chassignet, Eric P.

2014-06-01

21

Estimating population trends with a linear model: technical comments  

USGS Publications Warehouse

Controversy has sometimes arisen over whether there is a need to accommodate the limitations of survey design in estimating population change from the count data collected in bird surveys. Analyses of surveys such as the North American Breeding Bird Survey (BBS) can be quite complex; it is natural to ask if the complexity is necessary, or whether the statisticians have run amok. Bart et al. (2003) propose a very simple analysis involving nothing more complicated than simple linear regression, and contrast their approach with model-based procedures. We review the assumptions implicit to their proposed method, and document that these assumptions are unlikely to be valid for surveys such as the BBS. One fundamental limitation of a purely design-based approach is the absence of controls for factors that influence detection of birds at survey sites. We show that failure to model observer effects in survey data leads to substantial bias in estimation of population trends from BBS data for the 20 species that Bart et al. (2003) used as the basis of their simulations. Finally, we note that the simulations presented in Bart et al. (2003) do not provide a useful evaluation of their proposed method, nor do they provide a valid comparison to the estimating- equations alternative they consider.

Sauer, J.R.; Link, W.A.; Royle, J.A.

2004-01-01

22

Watershed-wide trend analysis of temperature characteristics in Karun-Dez watershed, southwestern Iran  

NASA Astrophysics Data System (ADS)

Trend estimation of climatic characteristics for a watershed is required to determine developing compatible strategies related to design, development, and management of water resources. In this study, the trends of the annual maximum ( T max), minimum ( T min), and mean ( T mean) air temperature; temperature anomaly ( T anomaly); and diurnal temperature range (DTR) time series at 13 meteorological stations located in the Karun-Dez watershed were analyzed using the Mann-Kendall and linear regression trend tests. The pre-whitening method was used to eliminate the influence of serial correlation on the Mann-Kendall test. The result showed increasing trends in the T min, T mean, and T anomaly series at the majority of stations and decreasing trend in the T max and DTR series. A geographical analysis of the trends revealed a broad warming trend in most of the watershed, and the cooling trends were observed only in the southern parts. Furthermore, the geographical pattern of the trends in the T mean and T anomaly series was similar, and the T max data did not show any dominant trend for the whole watershed. This study provides temperature change scenarios that may be used for the design of future water resource projects in the watershed.

Marofi, Safar; Soleymani, Samere; Salarijazi, Meysam; Marofi, Hossein

2012-10-01

23

The identification of distinct patterns in California temperature trends  

Microsoft Academic Search

Regional changes in California surface temperatures over the last 80 years are analyzed using station data from the US Historical\\u000a Climate Network and the National Weather Service Cooperative Network. Statistical analyses using annual and seasonal temperature\\u000a data over the last 80 years show distinctly different spatial and temporal patterns in trends of maximum temperature (Tmax)\\u000a compared to trends of minimum temperature (Tmin).

Eugene C. Cordero; Wittaya Kessomkiat; John Abatzoglou; Steven A. Mauget

2011-01-01

24

Global trends of measured surface air temperature  

Microsoft Academic Search

We analyze surface air temperature data from available meteorological stations with principal focus on the period 1880-1985. The temperature changes at mid- and high latitude stations separated by less than 1000 km are shown to be highly correlated; at low latitudes the correlation falls off more rapidly with distance for nearby stations. We combine the station data in a way

James Hansen; Sergej Lebedeff

1987-01-01

25

1973–1996 Trends in depth-averaged tropospheric temperature  

Microsoft Academic Search

The analysis of thickness derived from the National Center for Environmental Prediction (NCEP) reanalysis indicates that there has been no statistically significant warming trend in layer-averaged global tropospheric temperatures during the period 1979-1996. While this result is at variance with data based on surface information, NCEP trends and interannual variations are closely related to tropospheric mean-layer temperatures obtained from the

R. A. Pielke Sr; J. Eastman; T. N. Chase; J. Knaff; T. G. F. Kittel

1998-01-01

26

Temperature trends at high elevations: Patterns across the globe  

Microsoft Academic Search

Most climate models suggest amplification of global warming in high mountains, but observations are less clear. Using comprehensive, homogeneity-adjusted temperature records from over 1000 high elevation stations across the globe, we examine the causes of changing temperature trends with elevation, assessing the roles of free atmospheric change, topography (exposure and aspect), and cryospheric feedback. The data show that observed 20th

N. C. Pepin; J. D. Lundquist

2008-01-01

27

Technology and Development of High Temperature Superconducting Linear Motors  

Microsoft Academic Search

With the development of high temperature superconducting (HTS) materials, linear motor driving systems made using the HTS materials become available for practical applications. The HTS linear motor technology, especially structures and function characteristics, will be introduced in this paper. Comparison of the HTS linear motors with the conventional linear motors is also made and summarized with the potential HTS applications

Lu H. Zheng; Jian X. Jin; You G. Guo; Hai Y. Lu; Jian G. Zhu

28

Linear and nonlinear trending and prediction for AVHRR time series data  

NASA Technical Reports Server (NTRS)

The variability of AVHRR calibration coefficient in time was analyzed using algorithms of linear and non-linear time series analysis. Specifically we have used the spline trend modeling, autoregressive process analysis, incremental neural network learning algorithm and redundancy functional testing. The analysis performed on available AVHRR data sets revealed that (1) the calibration data have nonlinear dependencies, (2) the calibration data depend strongly on the target temperature, (3) both calibration coefficients and the temperature time series can be modeled, in the first approximation, as autonomous dynamical systems, (4) the high frequency residuals of the analyzed data sets can be best modeled as an autoregressive process of the 10th degree. We have dealt with a nonlinear identification problem and the problem of noise filtering (data smoothing). The system identification and filtering are significant problems for AVHRR data sets. The algorithms outlined in this study can be used for the future EOS missions. Prediction and smoothing algorithms for time series of calibration data provide a functional characterization of the data. Those algorithms can be particularly useful when calibration data are incomplete or sparse.

Smid, J.; Volf, P.; Slama, M.; Palus, M.

1995-01-01

29

Interpretation of Recent Temperature Trends in California  

SciTech Connect

Regional-scale climate change and associated societal impacts result from large-scale (e.g. well-mixed greenhouse gases) and more local (e.g. land-use change) 'forcing' (perturbing) agents. It is essential to understand these forcings and climate responses to them, in order to predict future climate and societal impacts. California is a fine example of the complex effects of multiple climate forcings. The State's natural climate is diverse, highly variable, and strongly influenced by ENSO. Humans are perturbing this complex system through urbanization, irrigation, and emission of multiple types of aerosols and greenhouse gases. Despite better-than-average observational coverage, we are only beginning to understand the manifestations of these forcings in California's temperature record.

Duffy, P B; Bonfils, C; Lobell, D

2007-09-21

30

Trend analysis of long-term temperature time series in the Greater Toronto Area (GTA)  

NASA Astrophysics Data System (ADS)

As the majority of the world’s population is living in urban environments, there is growing interest in studying local urban climates. In this paper, for the first time, the long-term trends (31-162 years) of temperature change have been analyzed for the Greater Toronto Area (GTA). Annual and seasonal time series for a number of urban, suburban, and rural weather stations are considered. Non-parametric statistical techniques such as Mann-Kendall test and Theil-Sen slope estimation are used primarily for the assessing of the significance and detection of trends, and the sequential Mann test is used to detect any abrupt climate change. Statistically significant trends for annual mean and minimum temperatures are detected for almost all stations in the GTA. Winter is found to be the most coherent season contributing substantially to the increase in annual minimum temperature. The analyses of the abrupt changes in temperature suggest that the beginning of the increasing trend in Toronto started after the 1920s and then continued to increase to the 1960s. For all stations, there is a significant increase of annual and seasonal (particularly winter) temperatures after the 1980s. In terms of the linkage between urbanization and spatiotemporal thermal patterns, significant linear trends in annual mean and minimum temperature are detected for the period of 1878-1978 for the urban station, Toronto, while for the rural counterparts, the trends are not significant. Also, for all stations in the GTA that are situated in all directions except south of Toronto, substantial temperature change is detected for the periods of 1970-2000 and 1989-2000. It is concluded that the urbanization in the GTA has significantly contributed to the increase of the annual mean temperatures during the past three decades. In addition to urbanization, the influence of local climate, topography, and larger scale warming are incorporated in the analysis of the trends.

Mohsin, Tanzina; Gough, William A.

2010-08-01

31

Recent Water Temperature Trends in the Lower Klamath River, California  

Microsoft Academic Search

Elevated water temperatures have been implicated as a factor limiting the recovery of anadromous salmonids in the Klamath River basin. This article reviews evidence of a multidecade trend of increasing temperatures in the lower main-stem Klamath River above the ocean and, based on model simulations, finds a high probability that water temperature has been increasing by approximately 0.5°C\\/decade (95% confidence

John M. Bartholow

2005-01-01

32

Recent water temperature trends in the lower Klamath River, California  

USGS Publications Warehouse

Elevated water temperatures have been implicated as a factor limiting the recovery of anadromous salmonids in the Klamath River basin. This article reviews evidence of a multi-decade trend of increasing temperatures in the lower main-stem Klamath River above the ocean and, based on model simulations, finds a high probability that water temperature has been increasing by approximately 0.5??C/decade (95% confidence interval [Cl] = 0.42-0.60??C/decade) since the early 1960s. The season of high temperatures that are potentially stressful to salmonids has lengthened by about 1 month over the period studied, and the average length of main-stem river with cool summer temperatures has declined by about 8.2 km/decade. Water temperature trends seem unrelated to any change in main-stem water availability but are consistent with measured basinwide air temperature increases. Main-stem warming may be related to the cyclic Pacific Decadal Oscillation, but if this trend continues it might jeopardize the recovery of anadromous salmonids in the Klamath River basin. ?? Copyright by the American Fisheries Society 2005.

Bartholow, J.M.

2005-01-01

33

20-Year Arctic Summer Seasonal Surface Temperature Trend  

NSDL National Science Digital Library

Here the 20-year seasonal surface temperature trend for the summer is shown over the Arctic region. This animation shows the warming and cooling regions in steps from the regions of least change to the areas of greatest change. Blue hues indicate cooling regions; red hues depict warming. Light regions indicate less change while darker regions indicate more. The temperature scale used ranges from -0.4 to +0.4 degrees Celsius in increments of .02 degrees. (See color bar below)

Starr, Cindy; Comiso, Josefino

2003-10-23

34

20-Year Arctic Spring Seasonal Surface Temperature Trend  

NSDL National Science Digital Library

Here the 20-year seasonal surface temperature trend for the spring is shown over the Arctic region. This animation shows the warming and cooling regions in steps from the regions of least change to the areas of greatest change. Blue hues indicate cooling regions; red hues depict warming. Light regions indicate less change while darker regions indicate more. The temperature scale used ranges from -0.4 to +0.4 degrees Celsius in increments of .02 degrees. (See color bar below)

Starr, Cindy; Comiso, Josefino

2003-10-23

35

20-Year Arctic Surface Temperature Trend with Alternate Color Scale  

NSDL National Science Digital Library

Here the 20-year surface temperature trend is shown over the Arctic region. This still images shows the warming and cooling regions. Blue hues indicate cooling regions; red hues depict warming. Light regions indicate less change while darker regions indicate more. The temperature scale used ranges from -0.14 to +0.4 degrees Celsius in increments of .02 degrees. (See color bar below)

Starr, Cindy; Comiso, Josefino

2003-10-23

36

20-Year Arctic Winter Seasonal Surface Temperature Trend  

NSDL National Science Digital Library

Here the 20-year seasonal surface temperature trend for the winter is shown over the Arctic region. This animation shows the warming and cooling regions in steps from the regions of least change to the areas of greatest change. Blue hues indicate cooling regions; red hues depict warming. Light regions indicate less change while darker regions indicate more. The temperature scale used ranges from -0.4 to +0.4 degrees Celsius in increments of .02 degrees. (See color bar below)

Starr, Cindy; Comiso, Josefino

2003-10-23

37

20-Year Arctic Autumn Seasonal Surface Temperature Trend  

NSDL National Science Digital Library

Here the 20-year seasonal surface temperature trend for the autumn is shown over the Arctic region. This animation shows the warming and cooling regions in steps from the regions of least change to the areas of greatest change. Blue hues indicate cooling regions; red hues depict warming. Light regions indicate less change while darker regions indicate more. The temperature scale used ranges from -0.4 to +0.4 degrees Celsius in increments of .02 degrees. (See color bar below)

Starr, Cindy; Comiso, Josefino

2003-10-23

38

Linear Relation of Temperature and Density at Unit Compressibility Factor  

Microsoft Academic Search

A linear relation is found for the experimental temperatures and densities at which the compressibility factor PV\\/RT equals unity. The two characteristic constants of the relation are evaluated for 12 gases for which appropriate data exist. The pertinent range of temperature and density for gases is from the critical temperature to the Boyle temperature, and from zero density to over

Eugene M. Holleran

1967-01-01

39

Recent trends of mean maximum and minimum air temperatures in the western half of Iran  

NASA Astrophysics Data System (ADS)

In this study, the trends of the annual, seasonal and monthly maximum ( T max) and minimum ( T min) air temperatures time series were investigated for 20 stations in the western half of Iran during 1966-2005. Three statistical tests including Mann-Kendall, Sen's slope estimator and linear regression were used for the analysis. The annual T max and T min series showed a positive trend in 85% of the stations and a negative trend in 15% of the stations in the study region. The highest increase of T max and T min values were obtained over Kermanshah and Ahwaz at the rates of (+)0.597°C/decade and (+)0.911°C/decade, respectively. On the seasonal scale, the strongest increasing trends were identified in T max and T min data in summer. The highest numbers of stations with positive significant trends occurred in the monthly T max and T min series in August. In contrast, the lowest numbers of stations with significant positive trends were observed between November and March. Overall, the results showed similar increasing trends for the study variables, although T min generally increased at a higher rate than T max in the study period.

Tabari, Hossein; Hosseinzadeh Talaee, Parisa

2011-03-01

40

Room Temperature Giant and Linear Magnetoresistance in Topological Insulator Bi2Te3 Nanosheets  

NASA Astrophysics Data System (ADS)

Topological insulators, a new class of condensed matter having bulk insulating states and gapless metallic surface states, have demonstrated fascinating quantum effects. However, the potential practical applications of the topological insulators are still under exploration worldwide. We demonstrate that nanosheets of a Bi2Te3 topological insulator several quintuple layers thick display giant and linear magnetoresistance. The giant and linear magnetoresistance achieved is as high as over 600% at room temperature, with a trend towards further increase at higher temperatures, as well as being weakly temperature-dependent and linear with the field, without any sign of saturation at measured fields up to 13 T. Furthermore, we observed a magnetic field induced gap below 10 K. The observation of giant and linear magnetoresistance paves the way for 3D topological insulators to be useful for practical applications in magnetoelectronic sensors such as disk reading heads, mechatronics, and other multifunctional electromagnetic applications.

Wang, Xiaolin; Du, Yi; Dou, Shixue; Zhang, Chao

2012-06-01

41

Increasing trend in the average temperature in Finland, 1847-2012  

NASA Astrophysics Data System (ADS)

The global average temperature has increased by about 0.8 ° C since the mid-19th century. It has been shown that this increase is statistically significant and that it can, for the most part, be attributed to human-induced climate change (IPCC 2007). A temperature increase is obvious also in regional and local temperatures in many parts of the world. However, compared with the global average temperature, the regional and local temperatures exhibit higher levels of noise, which has largely been removed from the global temperature due to the higher level of averaging. Because Finland is located in northern latitudes, it is subject to the polar amplification of climate change-induced warming, which is due to the enhanced melting of snow and ice and other feedback mechanisms. Therefore, warming in Finland is expected to be approximately 50% higher than the global average. Conversely, the location of Finland between the Atlantic Ocean and continental Eurasia causes the weather to be very variable, and thus the temperature signal is rather noisy. The change in mean temperature in Finland was investigated with Dynamic Linear Models (DLM) in order to define the sign and the magnitude of the trend in the temperature time series within the last 165 years. The data consisted of gridded monthly mean temperatures. The grid has a 10 km spatial resolution, and it was created by interpolating a homogenized temperature series measured at Finnish weather stations. Seasonal variation in temperature and the autocorrelation structure of the time series were taken account in the DLM models. We found that the Finnish temperature time series exhibits a statistically significant increasing trend, which is consistent with human-induced global warming. The mean temperature has risen clearly over 2° C in the years 1847-2012, which amounts to 0.16 ° C/decade. The warming rate before 1940's was close to the linear trend for the whole period, whereas the temperature change in the mid-20th century was negligible. However, the warming after the late 1960s has been remarkably fast. The model indicates that within the last 40 years the rate of change has been as high as 0.30 ° C/decade. The increase in temperature has been highest in spring and in late autumn but the change in summer months has not been so evident. The observed warming is somewhat higher than the global trend, which confirms the assumption that warming is stronger in higher latitudes.

Mikkonen, Santtu; Laine, Marko; Mäkelä, Hanna M.; Gregow, Hilppa; Tuomenvirta, Heikki; Lahtinen, Matti; Laaksonen, Ari

2014-05-01

42

Estimating time trends in Gumbel-distributed data by means of generalized linear models  

NASA Astrophysics Data System (ADS)

This paper shows how Gumbel-distributed data can be related to explanatory variables by using generalized linear models (GLMs) fitted by using a modified form of the iteratively weighted least squares algorithm (IWLS). Typical applications include (1) testing for trend in annual flood data, as a possible consequence of changing land cover or other factors; (2) testing for trend in annual maximum rainfall intensities of different durations, as a possible consequence of climate change; and (3) testing how annual maximum rainfall intensity is related to weather conditions at the times that annual maximum intensities were recorded. Given a first estimate of the Gumbel scale parameter ?, the coefficients ? of explanatory variables x are estimated by casting the model in GLM form, and the scale parameter ? is updated by solution of relevant maximum likelihood equation for this parameter. The parameters ?, ? can be readily estimated using currently available statistical software for fitting GLMs, which can also be used to test the significance of trends in annual flood data for which the Gumbel distribution is a plausible hypothesis. A plotting procedure to indicate departures from the Gumbel hypothesis is also given. The proposed procedure avoids the illogicality in which, when a trend in flood data is suspected, it is tested either by linear regression methods that assume Normally distributed residuals, or by nonparametric methods, both of which discard the Gumbel hypothesis. Simulated samples from Gumbel distributions were used to compare estimates of linear trend obtained by (1) the GLM procedure and (2) straightforward use of a Newton-Raphson procedure to locate the maximum of the likelihood surface; the GLM procedure converged more rapidly and was far less subject to numerical instabilities. Simulated samples from Gumbel distributions were also used to compare estimates of a linear trend coefficient ? given by the GLM procedure, with estimates of ? obtained by simple linear regression (LR). The variance of the distribution of GLM estimates of ? was less than the variance of the distribution of LR estimates, while comparison of the powers of the two tests showed that GLM was more powerful than LR at detecting the existence of small trends, although for large linear trends there was little to choose between the two methods.

Clarke, Robin T.

2002-07-01

43

Surface temperature trends in Russia over the past five centuries reconstructed from borehole temperatures  

E-print Network

Surface temperature trends in Russia over the past five centuries reconstructed from borehole in Russia and nearby areas to reconstruct the ground surface temperature history (GSTH) over the past five. D. Duchkov, I. V. Golovanova, S. Huang, V. A. Shchapov, and J. E. Smerdon, Surface temperature

Smerdon, Jason E.

44

Disparity of tropospheric and surface temperature trends: New evidence  

E-print Network

Observations suggest that the earth's surface has been warming relative to the troposphere for the last 25 years; this is not only difficult to explain but also contrary to the results of climate models. We provide new evidence that the disparity is real. Introducing an additional data set, R2 2 meter temperatures, a diagnostic variable related to tropospheric temperature profiles, we find trends derived from it to be in close agreement with satellite measurements of tropospheric temperature. This suggests that the disparity likely is a result of near-surface processes. We find that the disparity does not occur uniformly across the globe, but is primarily confined to tropical regions which are primarily oceanic. Since the ocean measurements are sea surface temperatures, we suggest that the disparity is probably associated with processes at the ocean-atmosphere interface. Our study thus makes unlikely some of the explanations advanced to account for the disparity; it also demonstrates the importance of disting...

Douglass, D H; Singer, F; Knappenberger, P C; Michaels, P J

2004-01-01

45

Impact of desertification on temperature trends in the Middle East.  

PubMed

The intense interest in desertification and climate change has stimulated detailed studies of temperature records in many areas of the world. In this investigation, the temperature records from the Middle East region are analyzed over the period 1950-1990. Results reveal a linear, statistically significant temperature increase of 0.07 °C/decade over the 41-year period. An analysis of spatial controls on these temperature changes reveals a warming effect associated with both overgrazing and the degree of human-induced desertification. The results of this study are consistent with theoretical and empirical studies predicting and demonstrating a warming signal associated with these land surface changes in the world's dryland areas. PMID:24197854

Nasrallah, H A; Balling, R C

1995-01-01

46

Diurnal and seasonal cycles of trends of surface air temperature Konstantin Y. Vinnikov  

E-print Network

Diurnal and seasonal cycles of trends of surface air temperature Konstantin Y. Vinnikov Department cycles of trends of surface air temperature and its variability using hourly observations from nine. Robock, and A. Basist, Diurnal and seasonal cycles of trends of surface air temperature, J. Geophys. Res

Robock, Alan

47

Unresolved issues with the assessment of multidecadal global land surface temperature trends  

E-print Network

Unresolved issues with the assessment of multidecadal global land surface temperature trends Roger documents various unresolved issues in using surface temperature trends as a metric for assessing global as well as surface atmospheric water vapor content on temperature trends, the quantification

Niyogi, Dev

48

Statistical significance of rising and oscillatory trends in global ocean and land temperature in the past 160 years  

E-print Network

Various interpretations of the notion of a trend in the context of global warming are discussed, contrasting the difference between viewing a trend as the deterministic response to an external forcing and viewing it as a slow variation which can be separated from the background spectral continuum of long-range persistent climate noise. The emphasis in this paper is on the latter notion, and a general scheme is presented for testing a multi-parameter trend model against a null hypothesis which models the observed climate record as an autocorrelated noise. The scheme is employed to the instrumental global sea-surface temperature record and the global land-temperature record. A trend model comprising a linear plus an oscillatory trend with period of approximately 60 yr, and the statistical significance of the trends, are tested against three different null models: first-order autoregressive process, fractional Gaussian noise, and fractional Brownian motion. The linear trend is significant in all cases, but the o...

Østvand, Lene; Rypdal, Martin

2013-01-01

49

Time series requirements and trends of temperature and precipitation extremes over Italy  

NASA Astrophysics Data System (ADS)

Extreme climate events have strong impacts on society and economy; accordingly,the knowledge of their trends on long period is crucial for the definition and implementation of a national adaptation strategy to climate change. The Research Programme on Climate Variability and Predictability (CLIVAR) identified a set of temperature and precipitation indices suited to investigate variability and trends of climate extremes. It is well known that extreme indices calculation is more demanding than first and second order statistics are: daily temperature and precipitation data are required and strict constrains in terms of continuity and completeness must be met. In addition, possible dishomogeneities affecting time series must be identified and adjusted before indices calculation. When metadata are not available, statistical methods can provide scientist a relevant support for homogeneity check; however, ad-hoc decision criteria (sometimes subjective) must be applied whenever contradictory results characterize different statistical homogeneity tests. In this work, a set of daily (minimum and maximum) temperature and precipitation time series for the period 1961-2011 were selected in order to guarantee a quite uniform spatial distribution of the stations over the Italian territory and according to the afore-said continuity and completeness criteria. Following the method described by Vincent, the homogeneity check of temperature time series was run at annual level. Two well-documented tests were employed (F-test and T-test), both implemented in the free R-package RHtestV3. The Vincent method was also used for a further investigation of time series homogeneity. Temperature dishomogeneous series were discarded. For precipitation series, no homogeneity check was run. The selected series were employed at daily level to calculate a reliable set of extreme indices. For each station, a linear model was employed for indices trend estimation. Finally, single station results were averaged to provide a "national" trend for Italy.

Fioravanti, Guido; Desiato, Franco; Fraschetti, Piero; Perconti, Walter; Piervitali, Emanuela

2013-04-01

50

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

51

Detection of temporal trends of ?- and ?-chlordane in Lake Erie fish communities using dynamic linear modeling.  

PubMed

Dynamic linear modeling (DLM) analysis was performed to identify the long-term temporal trends of two toxic components of the technical chlordane pesticide, ?- and ?-chlordane, in skinless-boneless muscle tissues of a number of sport fish species in Lake Erie. Our analysis considers the fish length as a covariate of the chlordane concentrations. The ?-chlordane models for the coho salmon, channel catfish, rainbow trout, and common carp showed continuously decreasing trends during the entire 30+ year survey period (1976-2007). The ?-chlordane models demonstrated similar trends for the coho salmon, channel catfish, and common carp. These fish species had higher levels of ?- and ?-chlordane in their muscle tissues. The ?- and ?-chlordane levels in freshwater drum, smallmouth bass, walleye, white bass, whitefish, and yellow perch decreased until the mid-1980s and hovered at levels around the detection limits for the remaining period. The pesticide biotransformation process, the reduction of contaminant emissions to the environment, the feeding habits of the different fish species, and the food-web alterations induced by the introduction of aquatic invasive species are some of the hypotheses proposed to explain the observed temporal trends in different fish species in Lake Erie. PMID:21536330

Ekram Azim, M; Letchumanan, Michelle; Abu Rayash, Azzam; Shimoda, Yuko; Bhavsar, Satyendra P; Arhonditsis, George B

2011-07-01

52

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

53

Filamentary microstructure and linear temperature dependence of normal state transport in optimized high temperature superconductors  

PubMed Central

A filamentary model of “metallic” conduction in layered high temperature superconductive cuprates explains the concurrence of normal state resistivities (Hall mobilities) linear in T (T?2) with optimized superconductivity. The model predicts the lowest temperature T0 for which linearity holds and it also predicts the maximum superconductive transition temperature Tc. The theory abandons the effective medium approximation that includes Fermi liquid as well as all other nonpercolative models in favor of countable smart basis states. PMID:11038596

Phillips, J. C.

1997-01-01

54

Linearized-moment analysis of the temperature jump and temperature defect in the Knudsen layer of a rarefied gas  

NASA Astrophysics Data System (ADS)

Understanding the thermal behavior of a rarefied gas remains a fundamental problem. In the present study, we investigate the predictive capabilities of the regularized 13 and 26 moment equations. In this paper, we consider low-speed problems with small gradients, and to simplify the analysis, a linearized set of moment equations is derived to explore a classic temperature problem. Analytical solutions obtained for the linearized 26 moment equations are compared with available kinetic models and can reliably capture all qualitative trends for the temperature-jump coefficient and the associated temperature defect in the thermal Knudsen layer. In contrast, the linearized 13 moment equations lack the necessary physics to capture these effects and consistently underpredict kinetic theory. The deviation from kinetic theory for the 13 moment equations increases significantly for specular reflection of gas molecules, whereas the 26 moment equations compare well with results from kinetic theory. To improve engineering analyses, expressions for the effective thermal conductivity and Prandtl number in the Knudsen layer are derived with the linearized 26 moment equations.

Gu, Xiao-Jun; Emerson, David. R.

2014-06-01

55

Trends in extreme temperature and precipitation in Muscat, Oman  

NASA Astrophysics Data System (ADS)

Changes in frequency and intensity of weather events often result in more frequent and intensive disasters such as flash floods and persistent droughts. In Oman, changes in precipitation and temperature have already been detected, although a comprehensive analysis to determine long-term trends is yet to be conducted. We analysed daily precipitation and temperature records in Muscat, the capital city of Oman, mainly focusing on extremes. A set of climate indices, defined in the RClimDex software package, were derived from the longest available daily series (precipitation over the period 1977-2011 and temperature over the period 1986-2011). Results showed significant changes in temperature extremes associated with cooling. Annual maximum value of daily maximum temperature (TX), on average, decreased by 1°C (0.42°C/10 year). Similarly, the annual minimum value of daily minimum temperature (TN) decreased by 1.5°C (0.61°C/10 year), which, on average, cooled at a faster rate than the maximum temperature. Consequently, the annual count of days when TX > 45°C (98th percentile) decreased from 8 to 3, by 5 days. Similarly, the annual count of days when TN < 15°C (2nd percentile) increased from 5 to 15, by 10 days. Annual total precipitation averaged over the period 1977-2011 is 81 mm, which shows a tendency toward wetter conditions with a 6 mm/10 year rate. There is also a significant tendency for stronger precipitation extremes according to many indices. The contribution from very wet days to the annual precipitation totals steadily increases with significance at 75% level. When The General Extreme Value (GEV) probability distribution is fitted to annual maximum 1-day precipitation, the return level of a 10-year return period in 1995-2011 was estimated to be 95 mm. This return level in the recent decade is about 70% higher than the return level for the period of 1977-1994. These results indicate that the long-term wetting signal apparent in total precipitation can be attributed largely to the increases in extreme precipitation in recent decades.

Gunawardhana, L. N.; Al-Rawas, G. A.

2014-09-01

56

Testing for deterministic trends in global sea surface temperature  

Microsoft Academic Search

The identification and estimation of trends is a frequent and fundamental task in the analysis of hydrometeorological records. The task is challenging because even time series generated by purely random processes can exhibit visually appealing trends that can be misleadingly taken as evidence of non-stationary behavior. Hydrometeorological time series exhibiting long range dependence can also exhibit trend-like features that can

Susana Barbosa

2010-01-01

57

Using fractional polynomials to model non-linear trends in longitudinal data.  

PubMed

Non-linear growth curves are discussed within the context of the linear mixed model. Non-linearity is modelled with time transformations known as fractional polynomials (FPs) having power terms that can be negative values and fractions with conventional polynomials (CPs) as a special case. Issues of interpretation are discussed with a focus on the instantaneous rate of change in models with and without static correlates. Methods for model selection are presented with emphasis on penalized and non-penalized indices of global fit based on the maximized likelihood and fitted models. Two empirical examples are presented with psychological data in which FPs were fitted along with CPs of equal and next highest order. The results show that the FPs had equal or better fit than the higher-order CPs and had prediction curves with as favourable or more favourable characteristics, such as less extreme behaviour at the edges of the observed time intervals. The results illustrate some of the potential advantages of FPs relative to CPs, which include parsimony, flexibility of curve shape, and the ability to approximate asymptotes. Though FPs are not necessarily suggested as replacements for CPs or other transformations (e.g. piecewise models), they might be useful when the goal is to model non-linear growth trends with smooth curves. PMID:19486548

Long, Jeffrey; Ryoo, Jihoon

2010-02-01

58

Estimation of the impact of land-surface forcings on temperature trends in eastern United States  

Microsoft Academic Search

We use the “observation minus reanalysis” difference (OMR) method to estimate the impact of land-use changes by computing the difference between the trends of the surface temperature observations (which reflect all the sources of climate forcing, including surface effects) and the NCEP-NCAR reanalysis surface temperatures (only influenced by the assimilated atmospheric temperature trends). This includes not only urbanization effects but

Eugenia Kalnay; Ming Cai; Hong Li; Jayakar Tobin

2006-01-01

59

Universal linear in temperature resistivity from black hole superradiance  

NASA Astrophysics Data System (ADS)

Observations across many families of unconventional materials motivate the search for robust mechanisms producing linear in temperature dc resistivity. Berezinskii-Kosterlitz-Thouless quantum phase transitions are commonplace in holographic descriptions of finite density matter, separating critical and ordered phases. We show that at a holographic Berezinskii-Kosterlitz-Thouless critical point, if the unstable operator is coupled to the current via irrelevant operators, then a linear contribution to the resistivity is universally obtained. We also obtain broad power law tails in the optical conductivity that shift spectral weight from the Drude peak as well as interband energy scales. We give a partial realization of this scenario using an Einstein-Maxwell-pseudoscalar bulk theory. The instability is a vectorial mode at nonzero wave vector, which is communicated to the homogeneous current via irrelevant coupling to an ionic lattice.

Donos, Aristomenis; Hartnoll, Sean A.

2012-12-01

60

Asymmetry of temperature trends at major industrial and non-industrial cities in India during 1901-2009 and possible role of aerosols  

NASA Astrophysics Data System (ADS)

Asymmetry in temperature trends in space and time over the Indian region have been examined to look for signatures of aerosols. Long term variations of seasonal and annual surface air temperature at 12 major cities have been studied, using data for the period 1901-2009, as well as comparative analysis of 6 non industrial cities has also be done. The change in the temperature for different periods 1901-2009, 1971-2009 and recent decade 2000-2009 has been examined by linear trend. Discussion Out of 12 stations, 7 stations showed the statistical significant warming trend, while only one station showed significant cooling trend in annual mean temperature during the period 1901-2009 and two stations showed non significant cooling trend( Table 1). The warming trend is observed in almost all the seasons ( DJF, MAM, JJAS and ON) at all the stations. Only three non Industrial stations showed warming trend in annual mean temperature. These three stations fall in the Peninsular India (South of 20°N), no significant warming trend is observed at the stations in North Indian (North of 20°N). During the recent period 1971-2009, all the industrial cities exhibited significant warming trend except two stations, where trend is nebulous, stations which showed cooling trend for the period 1901-2009 also showed warming trend in recent period. The increase in temperature may be due to enhance emission of greenhouse gases. For the case of non-industrial cities, only two stations namely Bijapur and Cuddalore showed warming trend while rest of the stations showed no trend or negative trend . These two stations fall in peninsular India. An aerosols concentrations over North India is higher than South India and it may attributes with asymmetry in temperature trend.Table 1: Liner trend (°C) in annual mean temperature at major industrial and non-industrial cities of India for different periods; 1901-2009 - Trend expressed as °C/100 years and trend for the period 1971-2009 expressed as °C/10 years

Kothawale, D. R.

2012-12-01

61

Urban bias influences on long-term California air temperature trends  

NASA Astrophysics Data System (ADS)

An analysis of 80-year shelter level temperature records at 112 California sites has been carried out. Results show that sea surface temperature (SST) and urban heat island effects influence the magnitude of the observed warming trend in the overall data set. These effects, however, are masked by averaging all temperature records together. While a warming trend existed in the overall data set, areas with such trends generally corresponded to areas containing the state's major population centers. Warming trend magnitude also increased with county population size, and 20 small inland towns and rural areas actually showed cooling trends. SST trends over the last 40 years showed cooling in mid-ocean areas and an anomalous warming at coastal sites. The warming was associated with a decline in the normal frequency of cold water upwelling in the coastal area. SST warming was found to be highly correlated with the warming of shelter level temperatures at coastal land observation sites.

Goodridge, James D.

62

Trend direction changes of Turkish temperature series in the first half of 1990s  

NASA Astrophysics Data System (ADS)

The presented study was concentrated on the trend analysis of the annual mean temperature series of 40 meteorological stations in all climatic zones of Turkey. The sensitivity of the parametric and nonparametric tests to the selected record periods was investigated in detail. Backward-shifted and forward-shifted trend analyses were accomplished by keeping either the beginning or the ending data period constant and varying the other period ending. This analysis resulted with a trend statistic direction turning point at the year 1992. Following this result, the trend tests were applied to three different records to distinguish the effect of 1992 on the trend direction. For the period 1950-1992, the downward trend was dominating several stations whereas only upward trend was observed for 1986-2006 period. Clearly, the trend direction change in 1992 dominated the trend behavior between 1986 and 2006. The opposite trend orientations on 1950-1992 and 1986-2006 periods seem to be neutralized on 1950-2006 period with the majority of the stations showing no trend as the result. This study displays the effect of different lengths of data record on the trend analysis results. It has been clear by this study that a sudden change on trend direction is obvious at the stations above 39°N in Turkey provinces in 1992. These results are conformed to the previous studies related with climate change like temperature, sea level, meteorological observations, and dominant climatic events as North Atlantic Oscillation and El-Niño and Southern Oscillation.

Dogan, Mustafa; Ulke, Asli; Cigizoglu, Hikmet Kerem

2014-07-01

63

A century of climate and ecosystem change in Western Montana: What do temperature trends portend?  

USGS Publications Warehouse

The physical science linking human-induced increases in greenhouse gasses to the warming of the global climate system is well established, but the implications of this warming for ecosystem processes and services at regional scales is still poorly understood. Thus, the objectives of this work were to: (1) describe rates of change in temperature averages and extremes for western Montana, a region containing sensitive resources and ecosystems, (2) investigate associations between Montana temperature change to hemispheric and global temperature change, (3) provide climate analysis tools for land and resource managers responsible for researching and maintaining renewable resources, habitat, and threatened/endangered species and (4) integrate our findings into a more general assessment of climate impacts on ecosystem processes and services over the past century. Over 100 years of daily and monthly temperature data collected in western Montana, USA are analyzed for long-term changes in seasonal averages and daily extremes. In particular, variability and trends in temperature above or below ecologically and socially meaningful thresholds within this region (e.g., -17.8??C (0??F), 0??C (32??F), and 32.2??C (90??F)) are assessed. The daily temperature time series reveal extremely cold days (??? -17.8??C) terminate on average 20 days earlier and decline in number, whereas extremely hot days (???32??C) show a three-fold increase in number and a 24-day increase in seasonal window during which they occur. Results show that regionally important thresholds have been exceeded, the most recent of which include the timing and number of the 0??C freeze/thaw temperatures during spring and fall. Finally, we close with a discussion on the implications for Montana's ecosystems. Special attention is given to critical processes that respond non-linearly as temperatures exceed critical thresholds, and have positive feedbacks that amplify the changes. ?? Springer Science + Business Media B.V. 2009.

Pederson, G. T.; Graumlich, L. J.; Fagre, D. B.; Kipfer, T.; Muhlfeld, C. C.

2010-01-01

64

Linearity between temperature peak and bioenergy CO2 emission rates  

NASA Astrophysics Data System (ADS)

Many future energy and emission scenarios envisage an increase of bioenergy in the global primary energy mix. In most climate impact assessment models and policies, bioenergy systems are assumed to be carbon neutral, thus ignoring the time lag between CO2 emissions from biomass combustion and CO2 uptake by vegetation. Here, we show that the temperature peak caused by CO2 emissions from bioenergy is proportional to the maximum rate at which emissions occur and is almost insensitive to cumulative emissions. Whereas the carbon-climate response (CCR; ref. ) to fossil fuel emissions is approximately constant, the CCR to bioenergy emissions depends on time, biomass turnover times, and emission scenarios. The linearity between temperature peak and bioenergy CO2 emission rates resembles the characteristic of the temperature response to short-lived climate forcers. As for the latter, the timing of CO2 emissions from bioenergy matters. Under the international agreement to limit global warming to 2 °C by 2100, early emissions from bioenergy thus have smaller contributions on the targeted temperature than emissions postponed later into the future, especially when bioenergy is sourced from biomass with medium (50-60 years) or long turnover times (100 years).

Cherubini, Francesco; Gasser, Thomas; Bright, Ryan M.; Ciais, Philippe; Strømman, Anders H.

2014-11-01

65

Differences between near-surface equivalent temperature and temperature trends for the Eastern United States. Equivalent temperature as an alternative measure of heat content  

USGS Publications Warehouse

There is currently much attention being given to the observed increase in near-surface air temperatures during the last century. The proper investigation of heating trends, however, requires that we include surface heat content to monitor this aspect of the climate system. Changes in heat content of the Earth's climate are not fully described by temperature alone. Moist enthalpy or, alternatively, equivalent temperature, is more sensitive to surface vegetation properties than is air temperature and therefore more accurately depicts surface heating trends. The microclimates evident at many surface observation sites highlight the influence of land surface characteristics on local surface heating trends. Temperature and equivalent temperature trend differences from 1982-1997 are examined for surface sites in the Eastern U.S. Overall trend differences at the surface indicate equivalent temperature trends are relatively warmer than temperature trends in the Eastern U.S. Seasonally, equivalent temperature trends are relatively warmer than temperature trends in winter and are relatively cooler in the fall. These patterns, however, vary widely from site to site, so local microclimate is very important. ?? 2006 Elsevier B.V. All rights reserved.

Davey, C.A.; Pielke, R.A., Sr.; Gallo, K.P.

2006-01-01

66

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

67

Ground vs. Surface Air Temperature Trends: Implications for Borehole Surface Temperature Reconstructions  

NASA Astrophysics Data System (ADS)

We have analyzed the relationship between surface air temperature (SAT), ground surface temperature (GST), and snowcover (SNC) over the terrestrial Northern Hemisphere based on a simulation with the NASA/GISS model 'E' employing observed SST and radiative forcing changes from 1951-1998. While SAT is the dominant influence on GST during the warm-season, it resolves only half of the variance in GST during the cold-season, with SNC and pre-conditioning by prior warm-season SAT also exhibiting a sizeable and, in places, dominant influence. A significant deficit of warming of GST relative to SAT (0.2 degrees C) during the period of greatest trend 1971-1998 is shown to be associated primarily with decreasing cold-season snowcover and a consequent greater associated exposure of the ground surface to winter cold air outbreaks.

Mann, M. E.; Schmidt, G. A.

2003-04-01

68

On the Urban Heat Island Effect Dependence on Temperature Trends  

Microsoft Academic Search

For U.S., Argentine and Australian cities, yearly mean urban to rural temperature differences (?Tu-r) and rural temperatures (Tr) are negatively correlated in almost every case, suggesting that urban heat island intensity depends, among other parameters on the temperature itself. This negative correlation is related to the fact that interannual variability of temperature is generally lower in urban environments than in

Inés Camilloni; Vicente Barros

1997-01-01

69

Urbanization effect on long-term trends of extreme temperature indices at Shijiazhuang station, North China  

NASA Astrophysics Data System (ADS)

Based on daily temperature data from an urban station and four rural stations of Shijiazhuang area in Hebei Province, North China, we analyzed the trends of extreme temperature indices series of the urban station (Shijiazhuang station) and rural stations during 1962-2011 and the urbanization effect on the extreme temperature indices of the urban station. The results showed that the trends of annual extreme temperature indices of the urban station and the rural stations are significantly different in the recent 50 years. Urbanization effect on the long-term trends of hot days, cold days, frost days, diurnal temperature range (DTR), extreme maximum temperature, and extreme minimum temperature at the urban station were all statistically significant, reaching 1.10 days/10 years, -2.30 days/10 years, -2.55 days/10 years, -0.20 °C/10 years, 0.16 °C/10 years, and 0.70 °C/10 years, respectively, with the urbanization contributions to the overall trends reaching 100, 38.0, 42.2, 40.0, 94.1, and 47.0 %, respectively. The urbanization effect on trend of ice days was also significant, reaching -0.47 days/10 years. However, no significant urbanization effect on trends of minimum values of maximum temperature and maximum values of minimum temperature had been detected. The urbanization effects in the DTR and extreme minimum temperature series of Shijiazhuang station in wintertime were highly significant.

Bian, Tao; Ren, Guoyu; Zhang, Bingxiang; Zhang, Lei; Yue, Yanxia

2014-02-01

70

Using Higher-Order Derivatives to Estimate Damped Linear Oscillator Models with an Over-Arching Temporal Trend  

E-print Network

to fit this type of data is the damped linear oscillator (DLO), which models constructs that vary about some equilibrium value over time. Currently, methods for fitting the DLO model require that no over-arching, temporal trend be present in the data...

Drotar, Scott

2013-05-31

71

Non-linear saturation mechanism of electron temperature gradient modes  

NASA Astrophysics Data System (ADS)

The electron temperature gradient (ETG) mode is a very plausible candidate to explain the large electron particle transport and thermal conduction. Production and identification of slab ETG modes and measurement electron transport have been already reported [X. Wei, V. Sokolov, and A. K. Sen, Phys. Plasmas 17, 042108 (2010); V. Sokolov and A. K. Sen, Phys. Rev. Lett. (2011)]. Now, we develop a theoretical model of non-linear saturation mechanism of ETG mode based on the three wave coupling of an unstable high frequency ETG mode with a damped ETG radial harmonic and a damped ion acoustic (IA) mode. Bicoherence analysis of Columbia linear machine (CLM) data show coupling between ETG modes (˜2.4 MHz) and a low frequency mode (˜50 kHz). The large damping drive of the ETG radial harmonic accompanied by the smaller but finite damping of the IA mode presents an energy sink for the unstable ETG mode, thus causing saturation. This model predicts a saturation level of ˜10% and agrees with the observed levels of ETG modes in the CLM.

Tokluoglu, E. K.; Sokolov, V.; Sen, A. K.

2012-10-01

72

Institute of Ecosystem Studies 1 ANALYSIS OF A WARMING TREND IN WATER TEMPERATURE IN THE  

E-print Network

are subject to warming due to global climate change but few studies to date have considered trends or rates to global warming are likely to profoundly alter estuaries and affect their capability of maintainingInstitute of Ecosystem Studies 1 ANALYSIS OF A WARMING TREND IN WATER TEMPERATURE IN THE HUDSON

Lovett, Gary M.

73

Sea Surface Temperature Trends of the Gulf Stream  

NSDL National Science Digital Library

In this activity, students use NASA satellite data to explore the seasonal changes in sea surface temperatures of the Gulf Stream. Students use NASA's Live Active Server (LAS) to generate data of sea surface temperatures in the Gulf Stream, which they then graph and analyze.

Roettger, Rex; Nasa

74

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.

75

Temperature trends at the surface and in the troposphere Konstantin Y. Vinnikov,1  

E-print Network

Temperature trends at the surface and in the troposphere Konstantin Y. Vinnikov,1 Norman C. Grody,2 in the Northern Hemisphere, the zonally averaged temperature at the surface increased faster than in the troposphere while at low latitudes of both hemispheres the temperature increased more slowly at the surface

Robock, Alan

76

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

77

Temperature and precipitation trends in Canada during the 20th century  

Microsoft Academic Search

Trends in Canadian temperature and precipitation during the 20th century are analyzed using recently updated and adjusted station data. Six elements, maximum, minimum and mean temperatures along with diurnal temperature range (DTR), precipitation totals and ratio of snowfall to total precipitation are investigated. Anomalies from the 1961–1990 reference period were first obtained at individual stations, and were then used to

Xuebin Zhang; Lucie A. Vincent; W. D. Hogg; Ain Niitsoo

2000-01-01

78

Temperature trends and Urban Heat Island intensity mapping of the Las Vegas valley area  

NASA Astrophysics Data System (ADS)

Modified urban climate regions that are warmer than rural areas at night are referred to as Urban Heat Islands or UHI. Islands of warmer air over a city can be 12 degrees Celsius greater than the surrounding cooler air. The exponential growth in Las Vegas for the last two decades provides an opportunity to detect gradual temperature changes influenced by an increasing presence of urban materials. This thesis compares ground based thermometric observations and satellite based remote sensing temperature observations to identify temperature trends and UHI areas caused by urban development. Analysis of temperature trends between 2000 and 2010 at ground weather stations has revealed a general cooling trend in the Las Vegas region. Results show that urban development accompanied by increased vegetation has a cooling effect in arid climates. Analysis of long term temperature trends at McCarran and Nellis weather stations show 2.4 K and 1.2 K rise in temperature over the last 60 years. The ground weather station temperature data is related to the land surface temperature images from the Landsat Thematic Mapper to estimate and evaluate urban heat island intensity for Las Vegas. Results show that spatial and temporal trends of temperature are related to the gradual change in urban landcover. UHI are mainly observed at the airport and in the industrial areas. This research provides useful insight into the temporal behavior of the Las Vegas area.

Black, Adam Leland

79

A comparison of regional trends in 1979-1997 depth-averaged tropospheric temperatures  

Microsoft Academic Search

ABSTRACT This study examines,regional temperature,trends during the period 1979?1997 from,the Microwave,Sounding,Unit (MSU) 2r satellite measurements,and,compares,them,with the same,trends in depth-averaged,tropospheric,tempera- tures derived from the National Center for Environmental Prediction (NCEP) reanalysis, in an attempt to determine whether regional trends exist which are larger than known inhomogeneities in the data. Large, statistically significant regional trends were found,in both the NCEP and the

Thomas N. Chase; Roger A. Pielke Sr.; John A. Knaff; Timothy G. F. Kittel; Joseph L. Eastman

2000-01-01

80

Long Term MSU Tropospheric and Ground Temperature Trends (1979-2008) Over Africa  

NASA Astrophysics Data System (ADS)

Africa, the second largest and second most populous continent, is marked by an arid desert zone in the north (10°-40°N), dense forest and tropical climate in the central region (10°S to 10°N), and a southern temperate zone (10°-40°S). The African landmass, which is symmetrically distributed across the equator, shows differential heating and cooling atmospheric (lower- and mid-tropospheric) temperature trends. The northern arid region, a main source of major dust storms and mineral dust aerosols, shows a larger warming trend compared to the central region characterized by dense forest and forest fires. The mean annual lower- and mid-tropospheric temperature trend (Microwave Sounding Units MSU, 1979-2008) is found be 0.023±0.006 °K/year and 0.018±0.003 °K/year respectively over northern Africa (Saharan region) as compared to 0.010±0.003 °K/year and 0.009±0.002 °K/year over the central equatorial, and mostly forest-covered region (Figure 1). The southern region shows a mean annual lower- and mid-tropospheric temperature trend of 0.015±0.004 °K/year and 0.011±0.003 °K/year, which is lower than the desert region. The dense tropical forest region near the equator shows the lowest tropospheric temperature trend (lower: 0.011±0.003 °K/year; mid: 0.007±0.002 °K/year) over the Africa (Figure 1). The warmest temperature trend was observed over the eastern Saharan region, covering parts of Egypt, Libya, and the northern parts of Sudan, Chad and Niger. We have also compared the MSU-derived atmospheric temperature trends to ground-based temperature trends available for Egypt and some surrounding regions. The mean annual MSU tropospheric trends over the Saharan region are relatively low compared to other major Asian deserts, such as the Taklamakan and the Gobi Desert in the northern mid-latitudes, which show a trend of 0.037±0.008 °K/year (lower) and 0.025±0.006 °K/year (mid). The seasonal and month-to-month variability of temperature trends over Africa and their comparison with other parts of the world will be discussed in detail. Figure 1. Long-term (30 years) mean annual MSU-derived tropospheric temperature trend (°K/year) over the African Continent.

Prasad, A. K.; El-Askary, H.; Kafatos, M.

2009-12-01

81

Studying the force characteristics of a high temperature superconducting linear synchronous motor  

NASA Astrophysics Data System (ADS)

A single-sided high temperature superconducting (HTS) linear synchronous motor (HTSLSM) with an HTS bulk magnet array as its secondary has been developed. A field-cooled magnetization system has also been developed to obtain the magnet array with alternate magnetic poles. In order to identify the performance and force characteristics of the HTSLSM, an equivalent 3D finite element analysis (FEA) model has been built up to analyze its field distributions and cogging force characteristics, and an experimental system has been constructed to measure its thrust and normal force characteristics. The traits of the thrust and the normal force have been extracted by comprehensive experiments, including the trends versus different exciting currents, different air gap lengths and variable magnetic poles. The analysis and experimental results are fundamental to the electromagnetic optimum design and control scheme evaluation for the HTSLSM.

Zheng, Luhai; Jin, Jianxun

2011-08-01

82

Temperature increasing trend due to solar activity at Western Saudi  

NASA Astrophysics Data System (ADS)

The Sun influnce on climate has been discussed globaly by many authors and at different latitudes. In this article we will discuss this connection for the Kingdom of Saudi Arabia, which spans a large area, i.e. 16-32 North and 36-50 East. We started our invistigation in this paper by looking into the temperature at the Western coast of the Kingdom, namely Yenbo and Jeddah. In order to find the correlation between temperature and solar variations we employed one of the most relevant solar quentity, i.e. the solar cycle length. From our invistigations we found an increase in the temperature averages reaching up to 1.0 degree Celsius in certain cities since 1970. It is also found that the temperature increase is strongly correlated with the solar Cycle length, reaching up to 0.8 in some sites.

Almleaky, Y. M.; Sharaf, M. A.; Basurah, H. M.; Malawi, A. A.; Al-Mostafa, Z. A.

83

Hawaiian forest bird trends: using log-linear models to assess long-term trends is supported by model diagnostics and assumptions (reply to Freed and Cann 2013)  

USGS Publications Warehouse

Freed and Cann (2013) criticized our use of linear models to assess trends in the status of Hawaiian forest birds through time (Camp et al. 2009a, 2009b, 2010) by questioning our sampling scheme, whether we met model assumptions, and whether we ignored short-term changes in the population time series. In the present paper, we address these concerns and reiterate that our results do not support the position of Freed and Cann (2013) that the forest birds in the Hakalau Forest National Wildlife Refuge (NWR) are declining, or that the federally listed endangered birds are showing signs of imminent collapse. On the contrary, our data indicate that the 21-year long-term trends for native birds in Hakalau Forest NWR are stable to increasing, especially in areas that have received active management.

Camp, Richard J.; Pratt, Thane K.; Gorresen, P. Marcos; Woodworth, Bethany L.; Jeffrey, John J.

2014-01-01

84

Temperature Trends at Four Stations of Assam during the period 1981-2010  

E-print Network

Abstract- One of the very important issues discussed in the recent two decades is climate change. Temperature is one of the indicative factors of climate change. The present research aimed at studying temporal variation in temperature over Guwahati, Tezpur, Dibrugarh (Mohanbari) and Silchar stations, Assam, India, during the period 1981–2010. Trends in annual and seasonal temperature series were analyzed using Mann-Kendall test. The analysis reveals that majority of the trends, both annual and seasonal, showed increasing tendency in temperature during the period 1981-2010.

Tanusree Deb Roy; Kishore K. Das

85

Predicting of Trend of Hemoglobin A1c in Type 2 Diabetes: A Longitudinal Linear Mixed Model  

PubMed Central

Background: There are some evidences that control the blood sugar decreasing the risk of diabetes complications, and even fatal. There are so many studies, but they are mostly cross-sectional and ignore the trend and hence it is necessary to implement a longitudinal study. The aim of this prospective study is to find the trend of glycosylated hemoglobin (HbA1c) over time and the associative factors on it. Methods: Participants of this longitudinal study were 3440 eligible diabetes patients referred to Isfahan Endocrine and Metabolism Research Center during 2000-2012 who are measured 2-40 times. A linear mixed model was applied to determine the association between HbA1c and variables, including lipids, systolic, diastolic blood pressure and complications such as nephropathy, and retinopathy. Furthermore, the effect of mentioned variables on trend of HbA1c was determined. Results: The fitted model showed total cholesterol, retinopathy, and the method of therapy including oral antidiabetic drugs (OADs) plus insulin and insulin therapy decreased the trend of HbA1c and high-density lipoprotein, weight, hyperlipidemia and the method of therapy including diet, and OADs increased the trend of HbA1c. Conclusions: The present study shows that regular visits of diabetic patients as well as controlling blood pressure, lipid profile, and weight loss can improve the trend of HbA1c levels during the time.

Kazemi, Elahe; Hosseini, Seyed Mohsen; Bahrampour, Abbass; Faghihimani, Elham; Amini, Masood

2014-01-01

86

Accounting for the effects of volcanoes and ENSO in comparisons of modeled and observed temperature trends  

NASA Astrophysics Data System (ADS)

Several previous studies have attempted to remove the effects of explosive volcanic eruptions and El Niño-Southern Oscillation (ENSO) variability from time series of globally averaged surface and tropospheric temperatures. Such work has largely ignored the nonzero correlation between volcanic signals and ENSO. Here we account for this collinearity using an iterative procedure. We remove estimated volcano and ENSO signals from the observed global mean temperature data, and then calculate trends over 1979-1999 in the residuals. Residual trends are sensitive to the choice of index used for removing ENSO effects and to uncertainties in key volcanic parameters. Despite these sensitivities, residual surface and lower tropospheric (2LT) trends are almost always larger than trends in the raw observational data. After removal of volcano and ENSO effects, the differential warming between the surface and lower troposphere is generally reduced. These results suggest that the net effect of volcanoes and ENSO over 1979-1999 was to reduce globally averaged surface and tropospheric temperatures and cool the troposphere by more than the surface. ENSO and incomplete volcanic forcing effects can hamper reliable assessment of the true correspondence between modeled and observed trends. In the second part of our study, we remove these effects from model data and compare simulated and observed residual trends. Residual temperature trends are not significantly different at the surface. In the lower troposphere the statistical significance of trend differences depends on the experiment considered, the choice of ENSO index, and the volcanic signal decay time. The simulated difference between surface and tropospheric warming rates is significantly smaller than observed in 51 out of 54 cases considered. We also examine multiple realizations of model experiments with relatively complete estimates of natural and anthropogenic forcing. ENSO and volcanic effects are not removed from these integrations. As in the case of residual trends, model and observed raw trends are in good agreement at the surface but differ significantly in terms of the trend differential between the surface and lower troposphere. Observed and simulated lower tropospheric trends are not significantly different in 17 out of 24 cases. Our study highlights the large uncertainties inherent in removing volcano and ENSO effects from atmospheric temperature data. It shows that statistical removal of these effects improves the correspondence between modeled and observed temperature trends over the satellite era. Accounting for volcanoes and ENSO cannot fully explain the observed warming of the surface relative to the lower troposphere, or why this differential warming is not reproduced in the model simulations considered here.

Santer, B. D.; Wigley, T. M. L.; Doutriaux, C.; Boyle, J. S.; Hansen, J. E.; Jones, P. D.; Meehl, G. A.; Roeckner, E.; Sengupta, S.; Taylor, K. E.

2001-11-01

87

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

USGS Publications Warehouse

We evaluated long-term trends in average maximum and minimum temperatures, threshold temperatures, and growing season in eastern Colorado, USA, to explore the potential shortcomings of many climate-change studies that either: (1) generalize regional patterns from single stations, single seasons, or a few parameters over short duration from averaging dissimilar stations: or (2) generalize an average regional pattern from coarse-scale general circulation models. Based on 11 weather stations, some trends were weakly regionally consistent with previous studies of night-time temperature warming. Long-term (80 + years) mean minimum temperatures increased significantly (P < 0.2) in about half the stations in winter, spring, and autumn and six stations had significant decreases in the number of days per year with temperatures ??? - 17.8 ??C (???0??F). However, spatial and temporal variation in the direction of change was enormous for all the other weather parameters tested, and, in the majority of tests, few stations showed significant trends (even at P < 0.2). In summer, four stations had significant increases and three stations had significant decreases in minimum temperatures, producing a strongly mixed regional signal. Trends in maximum temperature varied seasonally and geographically, as did trends in threshold temperature days ???32.2??C (???90??F) or days ???37.8??C (???100??F). There was evidence of a subregional cooling in autumn's maximum temperatures, with five stations showing significant decreasing trends. There were many geographic anomalies where neighbouring weather stations differed greatly in the magnitude of change or where they had significant and opposite trends. We conclude that sub-regional spatial and seasonal variation cannot be ignored when evaluating the direction and magnitude of climate change. It is unlikely that one or a few weather stations are representative of regional climate trends, and equally unlikely that regionally projected climate change from coarse-scale general circulation models will accurately portray trends at sub-regional scales. However, the assessment of a group of stations for consistent more qualitative trends (such as the number of days less than - 17.8??C, such as we found) provides a reasonably robust procedure to evaluate climate trends and variability. Copyright ?? 2002 Royal Meteorological Society.

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

2002-01-01

88

Recent trends in daily temperature extremes over southern Montenegro (1951-2010)  

NASA Astrophysics Data System (ADS)

Montenegro so far has been poorly investigated in terms of climate extremes. The aim of this paper was to analyse the extreme ETCCDI (Expert Team on Climate Change Detection and Indices) temperature indices in the Mediterranean region of Montenegro for the period of 1951-2010. Four stations in the coastal area of Montenegro have been analysed: Herceg Novi, Ulcinj, Budva and Bar. Two periods (before 1980 and after 1980) were separately investigated in this study due to a well-known climate shift that occurred in the late 1970s. Seven indices of temperature extremes have been chosen. The trend was analysed using a Mann-Kendall non-parametric test, while the slope was estimated using Sen's slope estimator. A negative trend has been calculated for cold nights and cold days at almost all stations. The most significant positive trends were obtained for warm conditions. The two separately investigated periods have shown contrasting temperature trends.

Buri?, D.; Lukovi?, J.; Duci?, V.; Dragojlovi?, J.; Doderovi?, M.

2014-01-01

89

Uncertainty of AMSU-A derived temperature trends in relationship with clouds and precipitation over ocean  

NASA Astrophysics Data System (ADS)

Microwave Sounding Unit (MSU) and Advanced Microwave Sounding Unit-A (AMSU-A) observations from a series of National Oceanic and Atmospheric Administration satellites have been extensively utilized for estimating the atmospheric temperature trend. For a given atmospheric temperature condition, the emission and scattering of clouds and precipitation modulate MSU and AMSU-A brightness temperatures. In this study, the effects of the radiation from clouds and precipitation on AMSU-A derived atmospheric temperature trend are assessed using the information from AMSU-A window channels. It is shown that the global mean temperature in the low and middle troposphere has a larger warming rate (about 20-30 % higher) when the cloud-affected radiances are removed from AMSU-A data. It is also shown that the inclusion of cloud-affected radiances in the trend analysis can significantly offset the stratospheric cooling represented by AMSU-A channel 9 over the middle and high latitudes of Northern Hemisphere.

Weng, F.; Zou, X.; Qin, Z.

2014-09-01

90

Understanding the trend in the Curie temperatures of Co{sub 2}-based Heusler compounds: Ab initio calculations  

SciTech Connect

The Curie temperatures for the Heusler compounds Co{sub 2}TiAl, Co{sub 2}VGa, Co{sub 2}VSn, Co{sub 2}CrGa, Co{sub 2}CrAl, Co{sub 2}MnAl, Co{sub 2}MnSn, Co{sub 2}MnSi, and Co{sub 2}FeSi are determined ab initio from the electronic structure obtained with the local-density functional approximation and/or the generalized gradient approximation. Frozen spin spirals are used to model the excited states needed to evaluate the spherical approximation for the Curie temperature. The spherical approximation is found to describe the experimental Curie temperatures very well which, for the compounds selected, extend over the range from 95 to 1100 K; as a function of the valence electron count, they show an approximately linear trend which finds an explanation by our calculations.

Kuebler, J.; Fecher, G. H.; Felser, C. [Institut fuer Festkoerperphysik, Technische Universitaet Darmstadt, D-64289 Darmstadt (Germany); Institut fuer Anorganische und Analytische Chemie, Johannes Gutenberg-Universitaet, D-55128 Mainz (Germany)

2007-07-01

91

The paradox of cooling streams in a warming world: regional climate trends do not parallel variable local trends in stream temperature in the Pacific continental United States  

USGS Publications Warehouse

Temperature is a fundamentally important driver of ecosystem processes in streams. Recent warming of terrestrial climates around the globe has motivated concern about consequent increases in stream temperature. More specifically, observed trends of increasing air temperature and declining stream flow are widely believed to result in corresponding increases in stream temperature. Here, we examined the evidence for this using long-term stream temperature data from minimally and highly human-impacted sites located across the Pacific continental United States. Based on hypothesized climate impacts, we predicted that we should find warming trends in the maximum, mean and minimum temperatures, as well as increasing variability over time. These predictions were not fully realized. Warming trends were most prevalent in a small subset of locations with longer time series beginning in the 1950s. More recent series of observations (1987-2009) exhibited fewer warming trends and more cooling trends in both minimally and highly human-influenced systems. Trends in variability were much less evident, regardless of the length of time series. Based on these findings, we conclude that our perspective of climate impacts on stream temperatures is clouded considerably by a lack of long-termdata on minimally impacted streams, and biased spatio-temporal representation of existing time series. Overall our results highlight the need to develop more mechanistic, process-based understanding of linkages between climate change, other human impacts and stream temperature, and to deploy sensor networks that will provide better information on trends in stream temperatures in the future.

Arismendi, Ivan; Johnson, Sherri; Dunham, Jason; Haggerty, Roy; Hockman-Wert, David

2012-01-01

92

Statistical Explanation for Trends in Extreme Summer Temperatures at Phoenix, Arizona  

Microsoft Academic Search

A reanalysis of the same Phoenix daily minimum and maximum temperature data examined by Balling et al. has been performed. As evidenced by substantial increasing trends in both the mean minimum and maximum temperatures, this area has experienced a marked heat island effect in recent decades. Balling et al. found that a statistical model for climate change in which simply

Lesley F. Tarleton; Richard W. Katz

1995-01-01

93

The analysis of trends and seasonal patterns of temperature and chlorophyll in a freshwater Scottish lake  

NASA Astrophysics Data System (ADS)

Information on temperature and chlorophyll concentration at global or regional scales in a lake is fundamental for the study of freshwater. Investigating long-term trends and seasonal patterns in these variables is essential in order to describe changes in lake characteristics. In this paper, several modelling approaches which consist of parametric and nonparametric regression models are applied to determine the trends over time and seasonal patterns in each of these two variables, from 1987 to 2005. Two sites of interest are Cailness and Creinch, which are located in the north and south basins, of Loch Lomond, respectively. The results show there is a significant trend in surface water temperature at Cailness. However, no significant trend is suggested in chlorophyll at both sites and there is evidence of constant seasonal patterns for all of the variables, at both sites.

Hamzah, Firdaus Mohamad; Ismail, Mohd Tahir; Mohammad, Rofizah; Sabri, Samsul Rijal Mohamad; Arbin, Norazman

2014-07-01

94

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.

95

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

96

Analysis of temperature trends, heat and cold waves in Central Italy (1952-2008)  

NASA Astrophysics Data System (ADS)

Most of the recent studies on climate change agree in assessing a positive global trend of the mean temperature. However, analysis of temperature data at basin scale appears to be quite complicated because of several factors affecting measures: location, slope exposition, distance from the sea, etc., resulting in a high meteorological variability also at short distances. In this study we present an analysis of minimum and maximum daily temperature data registered in Umbria Region (Tiber Basin, Central Italy) for the period 1952-2008 in order to estimate mean trends and possible increases in the "extreme events" such us "heat waves" and "cold waves". Among the about 80 stations available for the study period, only those ones with at least 45 years of data, even not consecutive, have been retained, resulting in a data set of only 5 stations. Data have been analyzed at annual and seasonal time scale, taking into account the spatial trend due to the elevation. The spatial correlation among stations appear to be quite high, but not related to the reciprocal distances. The time trend of each temperature time series has been studied by means of classical trend tests (Mann-Kendall and t-Student test). Results are comparable for the two tests but not unique for minimum and maximum temperature. Concerning Tmax, 3 out of 5 stations present a positive trend in the last 30 years, ranging from 0.02 to 0.09 °C/y, while the remaining two stations do not present any significant trend; however, the same stations show a negative trend over the period 1960-1990. This results in a positive trend over the whole period 1952-2008 ranging from 0.02 to 0.03 °C/y. Concerning Tmin, 3 out of 5 of the study stations do not present any statistically significant trend over the last 30 years, while one station shows a negative trend (- 0.05 °C/y) and one a positive trend (+ 0.07 °C/y); moreover, 3 out of 5 stations have a significant positive trend in the period 1952-2008 (the annual temperature gradient ranging from 0.02 to 0.04 °C/y), 1 station shows a significant negative trend (- 0.02 °C/y). The spatial dishomogeneity in the signal suggests that anthropic factors could influence very much the variations of temperatures in the last 60 years, preventing from using such data, like they are, as climatic indicators. The occurrence of "heat waves" has been analyzed considering the persistence of temperatures higher than the 90-th percentile for 5 consecutive days; analogously, the occurrence of "cold wave" has been found out considering the persistence of temperatures lower than the 10-th percentile for 5 consecutive days. Results indicate that in the last 20 years the number of heat waves has significantly increased with respect to the previous period, while an increasing of the cold waves has not been enhanced.

Romano, E.; Volpi, E.; Stefanucci, F.

2012-04-01

97

Stable isotopes in pedogenic calcite: Can the positive linear covariant trends be used to quantify paleo-evaporation rates?  

NASA Astrophysics Data System (ADS)

Paleoclimatological models suggest enhanced evaporation rates in subtropical regions during greenhouse- world conditions. Laboratory evaporation experiments show that calcites precipitated from variably saturated solutions yield a positive linear covariant trend (PLCT) in ?18O vs ?13C values. This investigation experimentally quantifies calcite PLCT so that ?13C of subtropical paleosol calcretes may be used as a regional proxy of paleo-evaporation rates. A series of powdered CaCO3 samples with ?18O and ?13C values of -19.6‰ and -37.2‰ VPDB respectively were dissolved in deionized water in a pressure sealed container; it also contained separate vials of calcite reacted with HCl to generate a range of pCO2 environments, thus simulating a soil atmosphere. The variable pCO2 conditions simulate expected soil atmosphere pCO2 conditions in a calcrete horizon during alternative phases of calcite dissolution and precipitation. After 24 hrs, the solutions were placed in an open beaker in an incubator at 36°C and allowed to evaporate. Aliquots of 100 ?L were removed at 24 hr intervals and the time of calcite crystal nucleation was also noted. Water analyses yielded ?18O enrichments ranging from an initial value of -4.8‰ VSMOW to a range of +10.0‰ to +14.8‰ VSMOW after an evaporation period of 75 hrs. The most enriched water values were attained from the solutions formed under lower pCO2 conditions (more enriched calcite ?18O, ?13C). The array of calcite ?18O vs ?13C values fall upon a PLCT that projects from a theoretical meteoric calcite line (MCL) calculated from the incubation temperature and deionized water ?18O and ?13C values. The precipitated calcite ?18O values range from the MCL value of -8.8‰ VPDB to +0.5‰ VPDB. The higher pCO2 waters precipitated calcite very early during evaporation, and thus the ?18O and ?13C calcite values are slightly enriched relative to the theoretical MCL. The lower pCO2 conditions precipitated calcite late in the evaporation of the fluids, and thus yield more enriched calcite ?18O and ?13C values. Ongoing experiments under warmer and cooler evaporation temperatures will aid in the development of a quantitative model for paleo-evaporation rates from paleosol calcretes.

Gröcke, D.; Ufnar, D.; Beddows, P. A.

2007-12-01

98

Recent warming trends inferred from borehole temperature data in Figuig area (Eastern Morocco)  

NASA Astrophysics Data System (ADS)

Ground surface temperature history (GSTH) reflecting the past climate conditions in eastern Morocco was evaluated by analyzing the temperature-depth profiles measured in four boreholes at the Figuig Oasis. The temperature-depth data were inverted using the functional space inversion method in order to reconstruct the surface temperature past changes. The results reveal a recent warming in the last century with an amplitude of 1-3 °C for the four boreholes and a comparison with surface air temperature (SAT) variation from the Bouarfa and Bechar meteorological stations confirms this result. This warming trend is confirmed by other climate proxies.

Ouzzaouit, Lalla Amina; Bakraoui, Alae; Benalioulhaj, Nouredine; Carneiro, Julio; Correia, Antonio; Jilali, Abdelhakim; Rimi, Abdelkrim; Zarhloule, Yassine

2014-08-01

99

Consistency of observed near surface temperature trends with climate change projections over the Mediterranean region  

NASA Astrophysics Data System (ADS)

We examine the possibility that anthropogenic forcing (Greenhouse gases and Sulfate aerosols, GS) is a plausible explanation for the observed near-surface temperature trends over the Mediterranean area. For this purpose, we compare annual and seasonal observed trends in near-surface temperature over the period from 1980 to 2009 with the response to GS forcing estimated from 23 models derived from CMIP3 database. We find that there is less than a 5% chance that natural (internal) variability is responsible for the observed annual and seasonal area-mean warming except in winter. Using additionally two pattern similarity statistics, pattern correlation and regression, we find that the large-scale component (spatial-mean) of the GS signal is detectable (at 2.5% level) in all seasons except in winter. In contrast, we fail to detect the small-scale component (spatial anomalies about the mean) of GS signal in observed trend patterns. Further, we find that the recent trends are significantly (at 2.5% level) consistent with all the 23 GS patterns, except in summer and spring, when 9 and 5 models respectively underestimate the observed warming. Thus, we conclude that GS forcing is a plausible explanation for the observed warming in the Mediterranean region. Consistency of observed trends with climate change projections indicates that present trends may be understood of what will come more so in the future, allowing for a better communication of the societal challenges to meet in the future.

Barkhordarian, Armineh; Bhend, Jonas; von Storch, Hans

2012-05-01

100

Annual and seasonal air temperature trend patterns of climate change and urbanization effects in relation to air pollutants in Turkey  

NASA Astrophysics Data System (ADS)

With a view to estimating climate change and ifs urban-induced bias in selected Turkish cities, we have used data from the period 1951 to 1990 recorded by 54 climate stations, four of which are corrected for their inhomogeneities. Two sets are produced; S1, including the large urban stations, and S2, consisting of rural, small urban and medium urban stations. Normalized Kendall trend test coefficients with a spatial prediction scheme, kriging, are used to construct spatial patterns of both sets together and separately. Results reveal a statistically significant cooling in mean temperatures mostly in northern regions and warming in minimum temperatures specific to large urban areas. Seasonal analysis shows that most of this cooling has been occurring in the summer and urban warming in the spring. The causes of cooling is investigated in relation to some air pollutants, SO2 and particulate matter (PM). Linear regressions performed on the time series resulted in a significant urban bias of 0.24°C per 40 years on mean temperatures and 0.56°C/40 years on minimum temperatures. In association with the above results, a decrease in the temperature range of 0.48°C over the period owing to urban bias was found. A 0.24°C urban bias magnitude of mean temperature trends is much greater than the results found on other three regions of the Earth [Jones et al., 1990]. An overall average cooling in mean temperatures, -0.07°C per decade, detected here is the same as Nasrallah and Balling's [1993] average result for the two grid points located over Turkey.

Tayanç, Mete; Karaca, Mehmet; Yenigün, Orhan

1997-01-01

101

Reconciling 20th Century Indo-Pacific ocean temperature trends in the instrumental record  

NASA Astrophysics Data System (ADS)

Large discrepancies exist between 20th century tropical Indo-Pacific sea surface temperature trends determined from current reconstructions. There is likewise some uncertainty about whether the related atmospheric Walker circulation has weakened or not in the twentieth century. These discrepancies prevent an unambiguous verification and validation of climate models used for projections of future climate change. In this talk I will present results from a recent study that demonstrates that a more consistent and robust trend among all the reconstructions can be found by filtering each dataset to remove ENSO, where ENSO is represented not by a single index time series but as an evolving dynamical process. That is, the discrepancies appear largely the result of different estimates of ENSO variability in each reconstruction. The robust ENSO-residual trend pattern represents a strengthening of the equatorial Pacific temperature gradient since 1900, due to a systematic warming trend in the warm pool and weak cooling in the cold tongue. Similarly filtering sea level pressure to remove ENSO variability results in a trend that is inconsistent with the suggestion of a systematic weakening of the Walker circulation over the same period. Additionally, I will show that none of the disparate estimates of post-1900 total eastern equatorial Pacific SST trends are larger than can be generated by statistically stationary, stochastically forced empirical models that reproduce ENSO evolution in each reconstruction.Figure 1: ENSO-residual SST trends, in units of °C/100 years, 1900-2010. (A) HadISST. (B) ERSST. (C) COBE. (D) KAPLAN. Stippling indicates trends are significant beyond the 95% confidence level based on ENSO-residual time series from LIMs constructed with lag covariance and noise statistics from each dataset.

Solomon, A.; Newman, M.

2012-12-01

102

Fitting and testing the significance of linear trends in Gumbel-distributed data  

Microsoft Academic Search

The widely-used hydrological procedures for calculating events with T-year return periods from data that follow a Gumbel distribution assume that the data sequence from which the Gumbel distribution is fitted remains stationary in time. If non-stationarity is suspected, whether as a consequence of changes in land-use practices or climate, it is common practice to test the significance of trend by

Robin T. Clarke

2002-01-01

103

Temperature and precipitation long-term trends and variations in the Ili-Balkhash Basin  

NASA Astrophysics Data System (ADS)

This study analyzed the long-term trends and variations of temperature and precipitation on annual timescale in the Ili-Balkhash Basin (IBB), Kazakhstan. Some statistical tools were employed to detect any climate variations at four stations in the IBB during the period between 1936 and 2005. These methods included the Mann-Kendall trend test, the Theil-Sen approach, and the sequential Mann-Kendall test. The results showed that in temporal scale, the climate in the IBB has been becoming warmer and wetter in the past several decades as a whole. The annual mean temperature and the annual precipitation in the IBB showed an increasing trend since the 1970s and the 1940s, respectively. The significance of the annual mean temperature and annual precipitation trends in the IBB was tested at >95 % confidence level. The slope of the increasing trend of annual mean temperature ranges from 0.019 to 0.029 °C/year, and that of the annual precipitation ranges from 0.654 to 2.179 mm/year. In spatial scale, the multiyear mean values of temperature and precipitation are greater in the southern mountain region than those in the northern plain and hilly land area of the basin. The multiyear mean temperature decreases with the increasing latitudes, while increases with the increasing altitudes except for Karaganda; the multiyear mean precipitation increase with the increasing altitudes, while decreases centered with the Lake Balkhash from the surrounding area. The results may provide climatic backgrounds for solving the problems related to water sources of the IBB.

Guo, Lidan; Xia, Ziqiang

2014-01-01

104

Modeled Global vs. Coastal Impacts on 1970 and 2005 Summer Daytime Temperature Trends in Coastal California  

Microsoft Academic Search

California summertime July to August (JJA) mean monthly air temperatures (1970-2005) were analyzed for two California air basins: South Coast (SoCAB) and the San Francisco Bay Area (SFBA), which extended into the Central Valley (CV). Daily Tmin and Tmax values were used to produce average monthly values and spatial distributions of and Tmax values trends for each air basin. Results

B. L. Habtezion; J. Gonzalez; R. D. Bornstein

2010-01-01

105

A statistical interpretation of surface ocean temperature trends during the Paleocene-Eocene Thermal Maximum  

E-print Network

! "! A statistical interpretation of surface ocean temperature trends during the Paleocene 90 Myr (Tjalsma and Lohmann, 1983; Thomas, 1990). Organisms inhabiting the sea surface, including of single-specimen surface-dwelling foraminifera at Southern Ocean ODP Site 690. We use Monte Carlo samples

Haran, Murali

106

Potential Biases in Inferring Holocene Temperature Trends from Long-Term Borehole Information  

NASA Astrophysics Data System (ADS)

We use a set of global coupled ocean-atmosphere general circulation model (OAGCM) experiments for timeslices over the Holocene from 9K Yr BP onwards to examine differences in Northern Hemisphere Ground Surface Temperature (GST) and Surface Air Temperature (SAT) trends. The model results are driven mainly by the orbitally-forced changes in seasonal insolation, and in particular, the increase in northern hemisphere seasonality in the mid Holocene. We see a significant increase in early to mid Holocene average GST compared to SAT as a result of a competition between the effects of changing seasonal insolation, and the varying extent of insulating seasonal snow cover. The model shows a mid-Holocene peak in annual mean terrestrial Northern Hemisphere GST, but not in annual Surface Air Temperatures (SAT). The model reproduces qualitatively the known trends in NH temperatures, but may underestimate their magnitude. However, the difference between GST and SAT trends appears to be a robust result from the greatly varying seasonal changes. We conclude that the factors influencing long-term GST trends are potentially quite complex, and that considerable care must be taken in interpreting SAT changes from the GST evidence when there is the possibility of substantial variation in seasonal warmth and snow cover.

Mann, M. E.; Schmidt, G. A.; Miller, S. K.; Legrande, A. N.

2008-12-01

107

Estimation of the impact of land-surface forcings on temperature trends in eastern United States  

E-print Network

of widespread land-use changes could be larger and should not be ignored. [3] Until recently, urbanization urban heat island impact are quoted in the IPCC [2001, p. 106] report, but both larger impacts [Kukla etEstimation of the impact of land-surface forcings on temperature trends in eastern United States

Kalnay, Eugenia

108

New report affirms surface global warming, but falls short of reconciling temperature trends  

Microsoft Academic Search

A new report by the U.S. National Research Council (NRC) affirms that the global surface temperature on Earth has warmed during the past 20 years. The report, issued on January 13, also says the lower to mid-troposphere has warmed less than the surface during the past two decades, and that a ``substantial disparity remains'' between these measurements. ``The warming trend

Randy Showstack

2000-01-01

109

Trends in the development of solid state amperometric and potentiometric high temperature sensors  

Microsoft Academic Search

High temperature sensors based on solid electrolytes are well established in many applications. In this context, stabilized zirconia as an oxygen ion conductor plays the key role to monitor oxygen. Recent trends in the use of stabilized zirconia aim at the detection of other exhaust or environmental gases like NOx, CO or hydrocarbons. This is possible by, e.g. monitoring currents

Wolfgang Göpel; Götz Reinhardt; Martin Rösch

2000-01-01

110

Air temperature trend and the impact on winter wheat phenology in Romania  

Microsoft Academic Search

Air temperature variability and trends in Romania were analysed using monthly, seasonal, and annual datasets. Temperature\\u000a data of winter wheat season were also analysed. The Mann-Kendall test, Sen’s slope estimate, the sequential version of the\\u000a Mann-Kendall test, the Pettitt test and spatial and temporal hierarchical cluster analyses were used. First, the datasets\\u000a were checked for changing points. The 106-year period

Adina-Eliza Croitoru; Iulian-Horia Holobaca; Catalin Lazar; Florin Moldovan; Alexandru Imbroane

2012-01-01

111

Taking China's Temperature: Daily Range, Warming Trends, and Regional Variations, 1955 2000  

Microsoft Academic Search

In analyzing daily climate data from 305 weather stations in China for the period from 1955 to 2000, the authors found that surface air temperatures are increasing with an accelerating trend after 1990. They also found that the daily maximum (Tmax) and minimum (Tmin) air temperature increased at a rate of 1.27° and 3.23°C (100 yr)-1 between 1955 and 2000.

Binhui Liu; Ming Xu; Mark Henderson; Ye Qi; Yiqing Li

2004-01-01

112

Trends in Maximum and Minimum Temperature Deciles in Select Regions of the United States  

Microsoft Academic Search

Daily maximum and minimum temperature data from 758 COOP stations in nineteen states are used to create temperature decile maps. All stations used contain records from 1948 through 2004 and could not be missing more than 5 consecutive years of data. Missing data are replaced using a multiple linear regression technique from surrounding stations. For each station, the maximum and

Rebecca Anne Smith

2007-01-01

113

Linear analysis of surface temperature dynamics and climate sensitivity  

E-print Network

series of 2D time-dependent non-orthogonal eigenmodes of global surface temperature are analytically derived and their geographic patterns are presented. The amplitudes of these modes have temporal characteristics and present exponentially decaying...

Wu, Wei

2007-04-25

114

Recent trends in regional air temperature and precipitation and links to global climate change in the Maharlo watershed, Southwestern Iran  

NASA Astrophysics Data System (ADS)

Trends in air temperature and precipitation data are investigated for linkages to global warming and climate change. After checking for serial correlation with trend-free pre-whitening procedure, the Mann-Kendall test is used to detect monotonic trends and the Mann-Whitney test is used for trend step change. The case study is Maharlo watershed, Southwestern Iran, representing a semi-arid environment. Data are for the 1951-2011 period, from four temperature sites and seven precipitation sites. A homogeneity test investigates regional similarity of the time series data. The results include mean annual, mean annual maximum and minimum and seasonal analysis of air temperature and precipitation data. Mean annual temperature results indicate an increasing trend, while a non-significant trend in precipitation is observed in all the stations. Furthermore, significant phase change was detected in mean annual air temperature trend of Shiraz station in 1977, indicating decreasing trend during 1951-1976 and increasing trend during 1977-2011. The annual precipitation analysis for Shiraz shows a non-significant decrease during 1951-1976 and 1977-2011. The result of homogeneity test reveals that the studied stations form one homogeneous region. While air temperature trends appear as regional linkage to global warming/global climate change, more definite outcome requires analysis of longer time series data on precipitation and air temperature.

Abolverdi, Javad; Ferdosifar, Ghasem; Khalili, Davar; Kamgar-Haghighi, Ali Akbar; Abdolahipour Haghighi, Mohammad

2014-11-01

115

Recent trends in regional air temperature and precipitation and links to global climate change in the Maharlo watershed, Southwestern Iran  

NASA Astrophysics Data System (ADS)

Trends in air temperature and precipitation data are investigated for linkages to global warming and climate change. After checking for serial correlation with trend-free pre-whitening procedure, the Mann-Kendall test is used to detect monotonic trends and the Mann-Whitney test is used for trend step change. The case study is Maharlo watershed, Southwestern Iran, representing a semi-arid environment. Data are for the 1951-2011 period, from four temperature sites and seven precipitation sites. A homogeneity test investigates regional similarity of the time series data. The results include mean annual, mean annual maximum and minimum and seasonal analysis of air temperature and precipitation data. Mean annual temperature results indicate an increasing trend, while a non-significant trend in precipitation is observed in all the stations. Furthermore, significant phase change was detected in mean annual air temperature trend of Shiraz station in 1977, indicating decreasing trend during 1951-1976 and increasing trend during 1977-2011. The annual precipitation analysis for Shiraz shows a non-significant decrease during 1951-1976 and 1977-2011. The result of homogeneity test reveals that the studied stations form one homogeneous region. While air temperature trends appear as regional linkage to global warming/global climate change, more definite outcome requires analysis of longer time series data on precipitation and air temperature.

Abolverdi, Javad; Ferdosifar, Ghasem; Khalili, Davar; Kamgar-Haghighi, Ali Akbar; Abdolahipour Haghighi, Mohammad

2014-08-01

116

Analysis of Precipitation and Temperature Trends in Sefid-Roud Basin  

E-print Network

Abstract—Temperature, humidity and precipitation in an area, are parameters proved influential in the climate of that area, and one should recognize them so that he can determine the climate of that area. Climate changes are of primary importance in climatology, and in recent years, have been of great concern to researchers and even politicians and organizations, for they can play an important role in social, political and economic activities. Even though the real cause of climate changes or their stability is not yet fully recognized, they are a matter of concern to researchers and their importance for countries has prompted them to investigate climate changes in different levels, especially in regional, national and continental level. This issue has less been investigated in our country. However, in recent years, there have been some researches and conferences on climate changes. This study is also in line with such researches and tries to investigate and analyze the trends of climate changes (temperature and precipitation) in Sefid-roud (the name of a river) basin. Three parameters of mean annual precipitation, temperature, and maximum and minimum temperatures in 36 synoptic and climatology stations in a statistical period of 49 years (1956-2005) in the stations of Sefid-roud basin were analyzed by Mann-Kendall test. The results obtained by data analysis show that climate changes are short term and have a trend. The analysis of mean temperature revealed that changes have a significantly rising trend, besides the precipitation has a significantly falling trend. I Keywords—Trend, Climate changes, Sefid-roud, Mann-Kendall

Amir G; Tahereh Soltani Gord Faramarzi; Parisa Safaripour Chafi; Abdol-reza Amani

117

Spatio-temporal long-term (1950-2009) temperature trend analysis in North Carolina, United States  

NASA Astrophysics Data System (ADS)

This study analyzed long-term (1950-2009) annual and seasonal time series data of maximum and minimum temperature from 249 uniformly distributed stations across the State of North Carolina, United States. The Mann-Kendall and Theil-Sen approach were applied to quantify the significance and magnitude of trend, respectively. A pre-whitening technique was applied to eliminate the effect of lag-1 serial correlation. For most stations over the period of the past 60 years, the difference between minimum and maximum temperatures was found decreasing with an overall increasing trend in the mean temperature. However, significant trends (confidence level ? 95 %) in the mean temperature analysis were detected only in 20, 3, 23, and 20 % of the stations in summer, winter, autumn, and spring, respectively. The magnitude of the highest warming trend in minimum temperature and the highest cooling trend in maximum temperature was +0.073 °C/year in the autumn season and -0.12 °C/year in the summer season, respectively. Additional analysis in mean temperature trend was conducted on three regions of North Carolina (mountain, piedmont, and coastal). The results revealed a warming trend for the coastal zone, a cooling trend for the mountain zone, and no distinct trend for the piedmont zone. The Sequential Mann-Kendall test results indicated that the significant increasing trends in minimum temperature and decreasing trend in maximum temperature had begun around 1970 and 1960 (change point), respectively, in most of the stations. Finally, the comparison between mean surface air temperature (SAT) and the North Atlantic Oscillation (NAO) concluded that the variability and trend in SAT can be explained partially by the NAO index for North Carolina.

Sayemuzzaman, Mohammad; Jha, Manoj K.; Mekonnen, Ademe

2014-05-01

118

Non-linear fitting method of finding equilibrium temperature from BHT data  

SciTech Connect

The real formation temperature is a very useful parameter in geothermal investigations and hydrocarbon maturation studies. Several models have been proposed for obtaining the real formation temperature from BHT data. This paper describes a non-linear fitting method of these models for obtaining equilibrium temperature and calculating the results from observed data. A preference is assumed for non-linear fitting Middleton's (1979) formula with observed data.

Li, D.X.

1986-01-01

119

Linear Regression Analysis of the Temperature-Shade Relationship  

E-print Network

throughout the year. Urban Heat Island at the Micro Scale The urban heat island effect (UHI) is defined. Ruddell4. References: Heat island effect. (2013, August 29); Urban Heat Island Comparison [Web Graphic as the the difference in temperature between an urban area and the surrounding countryside. Many UHI mitigation

Hall, Sharon J.

120

Upper-air temperature change trends above arid region of Northwest China during 1960-2009  

NASA Astrophysics Data System (ADS)

This study summarized upper-air temperature change trends based on the monthly datasets of 14 sounding stations in the arid region of Northwest China during 1960-2009. Over the investigated period, the change in upper-air temperature measured at eight standard pressure levels shows that an obvious warming at 850-400 hPa, which decreases with altitude, changes to an apparent cooling at 300-50 hPa. There is a positive correlation between the surface and 850-300-hPa temperatures, but a negative correlation between the surface and 200-50-hPa temperatures. Over the full 1960-2009 record, patterns of statistically significant mid-lower tropospheric warming and upper tropospheric and mid-lower stratospheric cooling are clearly evident. Also, the annual temperature cycle indicates that the peak temperature shifts from July in the troposphere to February in the mid-lower stratosphere, suggesting the importance of seasonal trend analysis. We found that the warming in the mid-lower troposphere is more pronounced during the summer, autumn, and winter, whereas the cooling in the upper troposphere and mid-lower stratosphere is larger during the summer and autumn. Furthermore, there are also many regional differences in the upper-air temperature change, regardless of both season and layer.

Chen, Zhongsheng; Chen, Yaning; Xu, Jianhua; Bai, Ling

2014-05-01

121

Trend analysis of temperature and precipitation in the Syr Darya Basin in Central Asia  

NASA Astrophysics Data System (ADS)

By investigating temperature and precipitation data from eight meteorological stations in the Syr Darya Basin (SDB) during 1881-2011 and 1891-2011, we analyzed trends using the Mann-Kendall (MK) test. Our results indicated that there was a notable increasing trend in annual temperature of 0.14 °C/decade (P < 0.05) and step change points in 1989 (P < 0.05). Similarly, annual precipitation showed a significant rising trend (P < 0.001) at a rate of 4.44 mm/decade and step change points in 1991 (P < 0.05). Overall, temperature and precipitation increases were more rapid in the plains than in the mountain areas. Furthermore, we found that temperature in the SDB region is strongly associated with the Asian Polar Vortex Area Index (APVAI, correlation coefficient: R = -0.701, P < 0.01) rather than with carbon dioxide emissions, especially in the plains area. For precipitation, the correlation coefficient is strongly associated with the Tibet Plateau Index (TPI, R = 0.490, P < 0.01), followed by the Antarctic Oscillation Index (AAOI, R = 0.343, P < 0.01), and the correlations in the plains are higher than those in the mountains. It is anticipated that the results of this study will further the understanding surrounding climate change in the SDB.

Yao, Junqiang; Chen, Yaning

2014-06-01

122

Trends in surface air temperature and temperature extremes in the Great Basin during the 20th century from ground-based observations  

NASA Astrophysics Data System (ADS)

We analyzed trends in surface air temperature and temperature extremes in the Great Basin during 1901-2010. We found that annual average daily minimum temperature increased significantly (0.9 ± 0.2°C) during the study period, with daily maximum temperature increasing only slightly. The asymmetric increase in daily minimum and maximum temperature resulted in daily diurnal temperature range (DTR) decreasing significantly from 1901 to 2010. Seasonally, increases in daily minimum temperature and decreases in DTR occurred in winter, summer, and autumn, but the rate of increase was faster in winter. In contrast, daily maximum temperature showed no significant trend in any season. These trends in temperature measures, however, were not monotonic with decadal periods that included either reversal or acceleration of century-scale trends. The trend magnitudes in temperatures were not significantly associated with elevations. Increases in daily minimum temperature resulted in a decrease in the number of frost days (-0.14 ± 0.04 day yr-1) and cool nights (-0.09 ± 0.04 night yr-1) from 1901 to 2010, while the number of warm days (0.11 ± 0.04 day yr-1) and warm nights (0.19 ± 0.03 night yr-1) increased significantly. Surprisingly, the number of cool days and the length of the growing season showed no significant trend during the study period. Thus, the results of this study suggest that continuation of the overall warming trend would lead to markedly warmer conditions in upcoming decades.

Tang, Guoping; Arnone, John A.

2013-05-01

123

An intercomparison of temperature trends in the U.S. Historical Climatology Network and recent atmospheric reanalyses  

E-print Network

An intercomparison of temperature trends in the U.S. Historical Climatology Network and recent 2012. [1] Temperature trends over 1979­2008 in the U.S. Historical Climatology Network (HCN Climatology Net- work and recent atmospheric reanalyses, Geophys. Res. Lett., 39, L10703, doi:10.1029/2012GL

124

Trend analysis of air temperature and precipitation time series over Greece: 1955-2010  

NASA Astrophysics Data System (ADS)

In this study, a database of air temperature and precipitation time series from the network of Hellenic National Meteorological Service has been developed in the framework of the project GEOCLIMA, co-financed by the European Union and Greek national funds through the Operational Program "Competitiveness and Entrepreneurship" of the Research Funding Program COOPERATION 2009. Initially, a quality test was applied to the raw data and then missing observations have been imputed with a regularized, spatial-temporal expectation - maximization algorithm to complete the climatic record. Next, a quantile - matching algorithm was applied in order to verify the homogeneity of the data. The processed time series were used for the calculation of temporal annual and seasonal trends of air temperature and precipitation. Monthly maximum and minimum surface air temperature and precipitation means at all available stations in Greece were analyzed for temporal trends and spatial variation patterns for the longest common time period of homogenous data (1955 - 2010), applying the Mann-Kendall test. The majority of the examined stations showed a significant increase in the summer maximum and minimum temperatures; this could be possibly physically linked to the Etesian winds, because of the less frequent expansion of the low over the southeastern Mediterranean. Summer minimum temperatures have been increasing at a faster rate than that of summer maximum temperatures, reflecting an asymmetric change of extreme temperature distributions. Total annual precipitation has been significantly decreased at the stations located in western Greece, as well as in the southeast, while the remaining areas exhibit a non-significant negative trend. This reduction is very likely linked to the positive phase of the NAO that resulted in an increase in the frequency and persistence of anticyclones over the Mediterranean.

Marougianni, G.; Melas, D.; Kioutsioukis, I.; Feidas, H.; Zanis, P.; Anandranistakis, E.

2012-04-01

125

Linear relation between TH (homogeneous ice nucleation temperature) and Tm (melting temperature) for aqueous solutions of sucrose, trehalose, and maltose  

NASA Astrophysics Data System (ADS)

Homogeneous ice nucleation temperatures ( THs) of aqueous sucrose, trehalose, and maltose solutions were measured together with melting temperatures ( Tms). It is shown that there is a linear relation between TH and Tm for these solutions. Almost identical supercooling behavior is observed for these aqueous disaccharide solutions.

Kanno, Hitoshi; Soga, Makoto; Kajiwara, Kazuhito

2007-08-01

126

Trends, interdecadal and interannual oscillations in global sea-surface temperatures  

Microsoft Academic Search

This study aims at a global description of climatic phenomena that exhibit some regularity during the twentieth century.\\u000a Multi-channel singular spectrum analysis is used to extract long-term trends and quasi-regular oscillations of global sea-surface\\u000a temperature (SST) fields since 1901. Regional analyses are also performed on the Pacific, (Northern and Southern) Atlantic,\\u000a and Indian Ocean basins. The strongest climatic signal is

V. Moron; R. Vautard; M. Ghil

1998-01-01

127

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

128

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

129

Nonlinear trends of net primary production of plants, surface temperature and water index in the south of the Krasnoyarsk Krai by satellite data  

NASA Astrophysics Data System (ADS)

There are rather many studies that investigate temporal variations in productivity of boreal forests using remote sensing data. Most of those studies, however, analyzed rather short time series: either for the time period between 1982 and 2000 or for the time period since 2000 till now (after the new satellite systems were launched). Moreover, even for longer periods of time (1982-2008), researchers usually considered linear trends, which do not objectively represent actual changes. Most of the studies estimated area-averaged trends rather than spatial distribution of the dynamics of NPP or another parameter. Verification of the averaged results using ground-based data often leads to ambiguous conclusions. Thus, linear models are not suitable for analyzing time series in complex, spatially distributed systems. In this study, we analyzed spatial distribution of nonlinear trends of net primary production of plants for the area in the south of the Krasnoyarsk Krai (in the Yenisei River basin) between 2000 and 2012. In addition, we analyzed spatial distribution of nonlinear trends of land surface temperature and water index (LSWI). NPP, temperature and water index values were calculated using the data from the MODIS scanner aboard the Terra satellite. Method used to decompose the time series was the nonlinear Seasonal-Trend Decomposition Procedure Based on Loess (STL). STL is a filtering procedure for decomposing a seasonal time series into seasonal, trend, and remainder (noise) components. STL consists of a sequence of applications of the Loess smoother. Spatial distribution of NPP trends in the study area showed differences in NPP variations for different plant communities growing in this area for the time period between 2000 and 2013. Decomposition of NPP time series revealed regions where NPP decreased increased or was stable over this period of time. Correlation analysis of trends NPP, temperature and water index, revealed regions with strong direct and inverse temperature and humidity dependence in the vegetation grow. This approach also allows defining zones of anthropogenic impact and dynamics of reclaimed after natural and anthropogenic influences. This work was partly supported by the Russian Foundation for Basic Research, project ? 13-06-00060

Larko, Aleksandr; Shevyrnogov, Anatoly

130

Future Climate Trends of Precipitation and Surface Temperature in Mexico under Global Warming  

NASA Astrophysics Data System (ADS)

Certainly the rise of greenhouse gases concentrations on the atmosphere due to anthropogenic causes has already started to show their influence on the actual world. These effects have the potential to change present climate variability and climate trends for the decades to come. This study focuses on calculating future climate trends based on the information coming from 23 CGCMs that participated on the recent 4th Assessment Report of the Intergovernmental Panel on Climate Change (IPCC). To resume the analysis, we previously performed a model validation for Mexico and chose the two best models that represent the actual climatology for the study region. The reference observed database was that of the Climatic Research Unit (CRU). Those results are shown in the submitted poster "Climate Trends of Precipitation and Surface Temperature for Different Observed Databases and IPCC Models in Mexico" from Martinez-Jimenez et al. also in this meeting. The validation study revealed that the ECHAM5 and the HADCM3 were the two models that better represented current climatology around Mexico and we present future climate trends for those two models under two emission scenarios (SRES-A1B and SRES-A2) around several zones in Mexico for the 2010-2098 period.

Montero-Martinez, M. J.; Pavon-Gonzalez, N.; Martinez-Jimenez, J.

2008-12-01

131

Trends in 1970-2010 southern California surface maximum temperatures: extremes and heat waves  

NASA Astrophysics Data System (ADS)

Daily maximum temperatures from 1970-2010 were obtained from the National Climatic Data Center (NCDC) for 28 South Coast Air Basin (SoCAB) Cooperative Network (COOP) sites. Analyses were carried out on the entire data set, as well as on the 1970-1974 and 2006-2010 sub-periods, including construction of spatial distributions and time-series trends of both summer-average and annual-maximum values and of the frequency of two and four consecutive "daytime" heat wave events. Spatial patterns of average and extreme values showed three areas consistent with climatological SoCAB flow patterns: cold coastal, warm inland low-elevation, and cool further-inland mountain top. Difference (2006-2010 minus 1970-1974) distributions of both average and extreme-value trends were consistent with the shorter period (1970-2005) study of previous study, as they showed the expected inland regional warming and a "reverse-reaction" cooling in low elevation coastal and inland areas open to increasing sea breeze flows. Annual-extreme trends generally showed cooling at sites below 600 m and warming at higher elevations. As the warming trends of the extremes were larger than those of the averages, regional warming thus impacts extremes more than averages. Spatial distributions of hot-day frequencies showed expected maximum at inland low-elevation sites. Regional warming again thus induced increases at both elevated-coastal areas, but low-elevation areas showed reverse-reaction decreases.

Ghebreegziabher, Amanuel T.

132

Impact of Sea Surface Temperature Trend on Late Summer Asian Rainfall in the 20th century  

NASA Astrophysics Data System (ADS)

The impact of the global sea surface temperature (SST) warming trend, which is the leading mode of SST variability, on late summer Asian rainfall is analyzed based on the simulations of five atmospheric general circulation models (AGCMs), which are performed by the U. S. Climate Variability and Predictability (CLIVAR) Drought Working Group. Our evaluations of the model outputs indicate that these models roughly capture the main features of climatological rainfall and circulations over Asia and the western North Pacific (WNP), but they simulate a too strong monsoon trough and a too northward shifted in the subtropical anticyclone in the WNP, and fail to reproduce the rainy belt over East Asia. It is found that all of the models simulate an intensified WNP subtropical high (WNPSH) in late summer, and an enhanced precipitation in the tropical Indian Ocean and the maritime continent, and a suppressed precipitation in the tropical WNP, when the models are forced with the SST trend, which is characterized by a significant increase in the Indian Ocean and western Pacific. All these changes are suggested to be dynamically coherent. In addition, precipitation changes forced by the SST trend are similar in the tropics, but show an apparent difference over extratropical Asia, in comparison with the observed rainfall trend. The possible reasons for this similarity and difference are discussed.

Bian, Qiying; Lu, Riyu

2013-04-01

133

Forcing of anthropogenic aerosols on temperature trends of the sub-thermocline southern Indian Ocean  

PubMed Central

In the late twentieth century, the sub-thermocline waters of the southern tropical and subtropical Indian Ocean experienced a sharp cooling. This cooling has been previously attributed to an anthropogenic aerosol-induced strengthening of the global ocean conveyor, which transfers heat from the subtropical gyre latitudes toward the North Atlantic. From the mid-1990s the sub-thermocline southern Indian Ocean experienced a rapid temperature trend reversal. Here we show, using climate models from phase 5 of the Coupled Model Intercomparison Project, that the late twentieth century sub-thermocline cooling of the southern Indian Ocean was primarily driven by increasing anthropogenic aerosols and greenhouse gases. The models simulate a slow-down in the sub-thermocline cooling followed by a rapid warming towards the mid twenty-first century. The simulated evolution of the Indian Ocean temperature trend is linked with the peak in aerosols and their subsequent decline in the twenty-first century, reinforcing the hypothesis that aerosols influence ocean circulation trends. PMID:23873281

Cowan, Tim; Cai, Wenju; Purich, Ariaan; Rotstayn, Leon; England, Matthew H.

2013-01-01

134

MODIS-Derived Nighttime Arctic Land-Surface Temperature Nascent Trends and Non-Stationary Changes  

NASA Astrophysics Data System (ADS)

Arctic nighttime Land-Surface Temperatures (LST) derived by the Moderate Resolution Imaging Spectroradiometer (MODIS) sensors onboard the NASA Terra and Aqua satellites are investigated. We use the local equator crossing times of 22:30 and 01:30, respectively, in the analysis of changes, trends and variations on the Arctic region and within 120-degree sectors. We show increases in the number of days above 0C and significant LST increase over decades of March 2000 through 2010 (MODIS Terra) and July 2002 through 2012 (MODIS Aqua). The MODIS Aqua nighttime Arctic LST change, +0.2 +/- 0.2C with P-value of 0.01 indicates a reduction relative to the MODIS Terra nighttime Arctic land-surface temperature change, +1.8 +/- 0.3C with P-value of 0.01. This reduction is a decadal non-stationary component of the Arctic land-surface temperature changes. The reduction is greatest, -1.3 +/- 0.2C with P-value of 0.01 in the Eastern Russia - Western North American sector of the Arctic during the July 2002 through 2012. Ref.: Muskett, R.R., "MODIS-Derived Nighttime Arctic Land-Surface Temperature Nascent Trends and Non-Stationary Changes," American Journal of Climate Change, in press January 2014. http://www.scirp.org/journal/ajcc/

Muskett, Reginald

2014-05-01

135

Oscillations, trends and anomalies in rainfall and air temperature in the principal cities in Bolivia  

NASA Astrophysics Data System (ADS)

Rainfall and temperature can be extremely variable in space and time especially in mountainous environment. The determination of climate variability and climate change needs a special assessment for water management. Increase our knowledge of the main climate trends in the region toward higher quality future climate determination is required. This research examines the anomalies of observed monthly rainfall and temperature data from 4 stations located in the principal cities in Bolivia (see Table below). Trends and anomalies in quantiles were determined for each station for monthly and 6-month seasonal block periods (wet period and dry period). The results suggest the presence of cycles rather than unidirectional trends. The Southern Oscillation Index (SOI) gives an indication of the development and intensity of El Niño or La Niña events in the Pacific Ocean. After determination of the anomalies for each of the stations, in both monthly rainfall and average temperature, together with the confidence intervals, comparison is made with the anomalies calculated in a similar way with data corresponding to the SOI. Comparison in cycles, shape and correlation has been performed between the anomalies from the observation data and the anomalies from the SOI with different time delay. The aim of this comparison is to identify the external influences of the anomalies in rainfall and temperature (Tele-connections). Influences have been identified during cycles of El Niño in the Andean zones La Paz, El Alto and Cochabamba dry cycles occur and in the most Amazonian side, Santa Cruz city, wet cycle is observed. This relation is opposite in La Niña periods.Meteorological stations under study;

Villazon, M. F.

2013-05-01

136

Are there spurious temperature trends in the United States Climate Division database?  

USGS Publications Warehouse

The United States (U.S.) Climate Division data set is commonly used in applied climatic studies in the United States. The divisional averages are calculated by including all available stations within a division at any given time. The averages are therefore vulnerable to shifts in average station location or elevation over time, which may introduce spurious trends within these data. This paper examines temperature trends within the 15 climate divisions of New England, comparing the NCDC's U.S. Divisional Data to the U.S. Historical Climate Network (USHCN) data. Correlation and multiple regression revealed that shifts in latitude, longitude, and elevation have affected the quality of the NCDC divisional data with respect to the USHCN. As a result, there may be issues with regard to their use in decadal-to century-scale climate change studies.

Keim, B.D.; Wilson, A.M.; Wake, C.P.; Huntington, T.G.

2003-01-01

137

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

138

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 tropical mean thermodynamic energy equation with Newtonian cooling for radiation is forced with two dynamical predictors: (i) the average eddy heat flux of both hemispheres; and (ii) tropical upwelling estimated from momentum balance following Randel et al. (2002). The correlation (1995-2011) for deseasonalised tropical average temperatures at 70 hPa with the eddy heat flux based predictor is 0.84 for ERA-Interim (0.77 for the momentum balance calculation), and 0.87 for MERRA. The eddy heat flux based predictor indicates a dynamically forced cooling of the tropics of ∼-0.1 K decade-1 (∼-0.2 K decade-1 excluding volcanic periods) for the period 1980-2011 in MERRA and ERA-Interim. ERA-Interim eddy heat fluxes drift slightly relative to MERRA in the 2000's, possibly due to onset of GPS temperature data assimilation. While NCEP gives a small warming trend, all 3 reanalyses show a similar seasonality, with strongest cooling in January/February (∼-0.4 K decade-1, from northern hemispheric forcing) and October (∼-0.3 K decade-1, from southern hemispheric forcing). Months preceding and following the peaks in cooling trends show pronounced smaller, or even warming, trends. Consequently, the seasonality in the trends arises in part due to a temporal shift in eddy activity. Over all months, the Southern Hemisphere contributes more to the tropical cooling in both MERRA and ERA-Interim. The residual time series (observed minus estimate of dynamically forced temperature) are well correlated between ERA-Interim and MERRA, with differences largely due to temperature differences. The residual time series is dominated by the modification of the radiative balance by volcanic aerosol following the eruption of El Chichon (maximum warming of ∼3 K at 70 hPa) and Pinatubo (maximum warming of ∼4 K at 70 hPa), with a strong dynamical response during Pinatubo partially masking the aerosol heating.

Fueglistaler, S.; Abalos, M.; Flannaghan, T. J.; Lin, P.; Randel, W. J.

2014-05-01

139

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

USGS Publications Warehouse

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

Friedel, Michael J.

2012-01-01

140

Long-term trends in thermospheric neutral temperature and density above Millstone Hill  

NASA Astrophysics Data System (ADS)

Incoherent scatter radar measurements of ionospheric temperature and density collected above Millstone Hill over the years 1976-2013 are analyzed to show the long-term trends in noontime neutral temperature and neutral O density over the height region 120-500 km. Exospheric temperature cooled by 69.3 ± 6.4 K over the period, an order of magnitude greater than that expected from greenhouse gas action. The O density dropped 0.081 ± 5.6% at 400 km altitude but rose by 36.9 ± 5.0% at 120 km over this period. This trend in density at 400 km agrees with that determined from satellite drag. The increase in density at 120 km counteracts the thermal contraction of the thermosphere expected to be associated with the cooling, resulting in only a small density response at 400 km. The long-term O density increase at 120 km may be caused by a long-term descent of the turbopause height of 4.2 km. Such a descent has been documented by a series of rocket mass spectrometer measurements.

Oliver, W. L.; Holt, J. M.; Zhang, S.-R.; Goncharenko, L. P.

2014-09-01

141

The warming trend of ground surface temperature in the Choshui Alluvial Fan, western central Taiwan  

NASA Astrophysics Data System (ADS)

Heat storage in subsurface of the continents forms a fundamental component of the global energy budget and plays an important role in the climate system. Several researches revealed that subsurface temperatures were being increased to 1.8-2.8°C higher in mean ground surface temperature (GST) for some Asian cities where are experiencing a rapid growth of population. Taiwan is a subtropic-tropic island with densely populated in the coastal plains surrounding its mountains. We investigate the subsurface temperature distribution and the borehole temperature-depth profiles by using groundwater monitoring wells in years 2000 and 2010. Our data show that the western central Taiwan plain also has been experiencing a warming trend but with a higher temperatures approximately 3-4 °C of GST during the last 250 yrs. We suggest that the warming were mostly due to the land change to urbanization and agriculture. The current GSTs from our wells are approximately 25.51-26.79 °C which are higher than the current surface air temperature (SAT) of 23.65 °C. Data from Taiwan's weather stations also show 1-1.5 °C higher for the GST than the SAT at neighboring stations. The earth surface heat balance data indicate that GST higher than SAT is reasonable. More researches are needed to evaluate the interaction of GST and SAT, and how a warming GST's impact to the SAT and the climate system of the Earth.

Chen, W.; Chang, M.; Chen, J.; Lu, W.; Huang, C. C.; Wang, Y.

2013-12-01

142

Relative Contribution of Greenhouse Gases and Ozone Change to Temperature Trends in the Stratosphere: A Chemistry/Climate Model Study  

NASA Technical Reports Server (NTRS)

Long-term changes in greenhouse gases, primarily carbon dioxide, are expected to lead to a warming of the troposphere and a cooling of the stratosphere. We examine the cooling of the stratosphere and compare the contributions greenhouse gases and ozone change for the decades between 1980 and 2000. We use 150 years of simulation done with our coupled chemistry/climate model (GEOS 4 GCM with GSFC CTM chemistry) to calculate temperatures and constituents fiom,1950 through 2100. The contributions of greenhouse gases and ozone to temperature change are separated by a time-series analysis using a linear trend term throughout the period to represent the effects of greenhouse gases and an equivalent effective stratospheric chlorine (EESC) term to represent the effects of ozone change. The temperature changes over the 150 years of the simulation are dominated by the changes in greenhouse gases. Over the relatively short period (approx. 20 years) of ozone decline between 1980 and 2000 changes in ozone are competitive with changes in greenhouse gases. The changes in temperature induced by the ozone change are comparable to, but smaller than, those of greenhouse gases in the upper stratosphere (1-3 hPa) at mid latitudes. The ozone term dominates the temperature change near both poles with a negative temperature change below about 3-5 hPa and a positive change above. At mid latitudes in the upper stratosphere and mesosphere (above about 1 hPa) and in the middle stratosphere (3 to 70 ma), the greenhouse has term dominates. From about 70 hPa down to the tropopause at mid latitudes, cooling due to ozone changes is the largest influence on temperature. Over the 150 years of the simulation, the change in greenhouse gases is the most important contributor to temperature change. Ozone caused a perturbation that is expected to reverse over the coming decades. We show a model simulation of the expected temperature change over the next two decades (2006-2026). The simulation shows a crossover between lower atmospheric heating and upper atmospheric cooling that is located at about 90 hPa in the tropics and 30-40 hPa in the polar regions. This results from the combination of continuing increases in greehouse gases and recovery from ozone depletion.

Stolarski, Richard S.; Douglass, A. R.; Newman, P. A.; Pawson, S.; Schoeberl, M. R.

2006-01-01

143

Fitting and testing the significance of linear trends in Gumbel-distributed data Hydrology and Earth System Sciences, 6(1), 1724 (2002) EGS  

E-print Network

such as that of Mann-Kendall, which makes no assumption about the distribution of the data. Thus, the hypothesis-parametric Mann-Kendall test) were compared. The ML test was always more powerful than either the Linear Regression or Mann-Kendall test, whatever the (positive) value of the trend ; the power of the MK test

Boyer, Edmond

144

A high-speed spatial (linear) scanning pyrometer: A tool for diagnostics, temperature mapping, and property determinations at high temperatures  

NASA Technical Reports Server (NTRS)

Development of a fast spatial scanning pyrometer for temperature measurements above 1500 K is described. The salient features of the pyrometer are: (1) it measures spectral radiance temperature (at 0.65 micron) at 1024 points along a straight line (25 mm long) on the target; (2) it has no moving parts and uses a self-scanning linear array of silicon photodiodes as the detector; (3) its output is recorded digitally every 1 microsec with a full-scale resolution of about 1 part in 4000, permitting performance of a complete cycle of measurements (1024 points) in about 1 ms. Operational characteristics of the pyrometer are given. Examples of measurements of the temperature along rapidly heated (resistive self-heating) specimens (rod, tube, strip) are presented. Potential use of the pyrometer in the experiments, both ground-based and in microgravity, requiring temperature mapping and property distribution of the specimen at high temperatures is discussed.

Cezairliyan, A.; Chang, R. F.; Foley, G. M.

1990-01-01

145

Non-Markovian Quantum State Diffusion for Temperature-Dependent Linear Spectra of Light Harvesting Aggregates  

E-print Network

Non-Markovian Quantum State Diffusion (NMQSD) has turned out to be an effective method to calculate excitonic properties of aggregates composed of organic chromophores, taking into account the strong coupling of electronic transitions to vibrational modes of the chromophores. In this paper we show how to calculate linear optical spectra at finite temperatures in an efficient way. To this end we map a finite temperature environment to the zero temperature case using the so-called thermofield method. The zero temperature case equations can then be solved efficiently by standard integrators. As an example we calculate absorption and circular dichroism spectra of a linear aggregate. The formalism developed can be applied to calculate arbitrary correlation functions.

Ritschel, Gerhard; Möbius, Sebastian; Strunz, Walter T; Eisfeld, Alexander

2014-01-01

146

Non-Markovian Quantum State Diffusion for Temperature-Dependent Linear Spectra of Light Harvesting Aggregates  

E-print Network

Non-Markovian Quantum State Diffusion (NMQSD) has turned out to be an effective method to calculate excitonic properties of aggregates composed of organic chromophores, taking into account the strong coupling of electronic transitions to vibrational modes of the chromophores. In this paper we show how to calculate linear optical spectra at finite temperatures in an efficient way. To this end we map a finite temperature environment to the zero temperature case using the so-called thermofield method. The zero temperature case equations can then be solved efficiently by standard integrators. As an example we calculate absorption and circular dichroism spectra of a linear aggregate. The formalism developed can be applied to calculate arbitrary correlation functions.

Gerhard Ritschel; Daniel Süß; Sebastian Möbius; Walter T. Strunz; Alexander Eisfeld

2014-08-30

147

Trend analysis and change point detection of annual and seasonal precipitation and temperature series over southwest Iran  

NASA Astrophysics Data System (ADS)

This paper presents results of trend analysis and change point detection of annual and seasonal precipitation, and mean temperature (TM), maximum temperature (TMAX) and minimum temperature (TMIN) time series of the period 1950-2007. Investigations were carried out for 50 precipitation stations and 39 temperature stations located in southwest Iran. Three statistical tests including Pettitt's test, Sequential Mann-Kendall test (SQ-MK test) and Mann-Kendall rank test (MK-test) were used for the analysis. The results obtained for precipitation series indicated that most stations showed insignificant trends in annual and seasonal series. Out of the stations which showed significant trends, highest numbers were observed during winter season while no significant trends were detected in summer precipitation. Moreover, no decreasing significant trends were detected by statistical tests in annual and seasonal precipitation series. The analysis of temperature trends revealed a significant increase during summer and spring seasons. TMAX was more stable than TMIN and TM, and winter was stable compared to summer, spring and autumn seasons. The results of change point detection indicated that most of the positive significant mutation points in TM, TMAX and TMIN began in the 1990s.

Zarenistanak, Mohammad; Dhorde, Amit G.; Kripalani, R. H.

2014-03-01

148

Trends in daily precipitation and temperature extremes across western Germany in the second half of the 20th century  

NASA Astrophysics Data System (ADS)

The evolution of daily extreme precipitation and temperature from 1958 to 2001 was investigated within the German side of the Rhine basin. Trends of a set of extreme precipitation and temperature indices defined on daily time series of precipitation and temperature were calculated at 611 precipitation and 232 temperature stations located within the study area and their corresponding significances were tested using the non-parametric Kendall- tau test. The results obtained indicated that both the daily minimum and maximum extreme temperatures have increased over the investigation period, with the degree of change showing seasonal variability. On an annual basis, the change in the daily minimum extreme temperature was found to be greater than that of the daily maximum extreme temperature. The daily extreme heavy precipitation has shown increasing trends both in magnitude and frequency of occurrence in all seasons except summer, where it showed the opposite trend. The station values of the daily precipitation were also interpolated on a regular grid of 5 km × 5 km so that the changes in the indices could be investigated on areal precipitation by aggregating the interpolated precipitation to any desired scale. This enables assessment of the hydrological consequences of the changes in the extreme precipitation. Although the spatial pattern remained more or less similar with that of the point-scale trends for all indices, the average trend magnitude showed an increase with the scale of the area on which precipitation was aggregated.

Hundecha, Yeshewatesfa; Bárdossy, András

2005-07-01

149

Is the Curve Relating Temperature to Aggression Linear or Curvilinear?: Assaults and Temperature in Minneapolis Reexamined  

Microsoft Academic Search

Using archival data from Minneapolis recorded in 3-hr time intervals, E. G. Cohn and J. Rotton (1997) concluded that there is an inverted U-shaped relationship between temperature and assault, with the maximum assault rate occurring at 74.9 °F. They depicted this relationship by plotting temperature against assault. This plot, however, fails to take into account time of day. Time of

Brad J. Bushman; Morgan C. Wang; Craig A. Anderson

2005-01-01

150

Linear viscoelastic limits of asphalt concrete at low and intermediate temperatures  

Microsoft Academic Search

The purpose of this dissertation is to demonstrate the hypothesis that a region at which the behavior of asphalt concrete can be represented as a linear viscoelastic material can be determined at low and intermediate temperatures considering the stresses and strains typically developed in the pavements under traffic loading. Six mixtures containing different aggregate gradations and nominal maximum aggregate sizes

Yusuf A. Mehta

1999-01-01

151

Mercury trends in predatory fish in Great Slave Lake: the influence of temperature and other climate drivers.  

PubMed

Here we report on trends in mercury (Hg) concentrations in lake trout (Salvelinus namaycush), burbot (Lota lota), and northern pike (Esox lucius) from Great Slave Lake, located in the Mackenzie River Basin (MRB) and investigate how climate factors may be influencing these trends. Hg concentrations in lake trout and burbot increased significantly over the early 1990s to 2012 in the two major regions of the lake; no trend was evident for northern pike over 1999-2012. Temporal variations in Hg concentrations in lake trout and burbot were similar with respect to timing of peaks and troughs. Inclusion of climate variables based on annual means, particularly temperature, improved explanatory power for variations in Hg over analyses based only on year and fish length; unexpectedly, the temperature coefficient was negative. Climate analyses based on growing season means (defined as May-September) had less explanatory power suggesting that trends were more strongly associated with colder months within the year. Inclusion of the Pacific/North American index improved explanatory power for the lake trout model suggesting that trends may have been affected by air circulation patterns. Overall, while our study confirmed previously reported trends of Hg increase in burbot in the MRB, we found no evidence that these trends were directly driven by increasing temperatures and productivity. PMID:24111928

Evans, Marlene; Muir, Derek; Brua, Robert B; Keating, Jonathan; Wang, Xiaowa

2013-11-19

152

Temperature dependence of mode conversion in warm, unmagnetized plasmas with a linear density profile  

SciTech Connect

We study theoretically the linear mode conversion between electromagnetic waves and Langmuir waves in warm, stratified, and unmagnetized plasmas, using a numerically precise calculation based on the invariant imbedding method. We verify that the principle of reciprocity for the forward and backward mode conversion coefficients holds precisely regardless of temperature. We also find that the temperature dependence of the mode conversion coefficient is substantially stronger than that previously reported. Depending on the wave frequency and the incident angle, the mode conversion coefficient is found to increase or decrease with the increase of temperature.

Yu, Dae Jung; Lee, Dong-Hun [School of Space Research, Kyung Hee University, Yongin (Korea, Republic of)] [School of Space Research, Kyung Hee University, Yongin (Korea, Republic of); Kim, Kihong [Division of Energy Systems Research, Ajou University, Suwon (Korea, Republic of)] [Division of Energy Systems Research, Ajou University, Suwon (Korea, Republic of)

2013-06-15

153

Linear Sigma Model at Finite Temperature and Baryonic Chemical Potential Using the Midpoint Technique  

E-print Network

A baryonic chemical potential is included in the linear sigma model at finite temperature. The effective mesonic potential is numerically calculated using the midpoint technique. The meson masses are investigated as functions of the temperature at fixed value of baryonic chemical potential. The pressure and energy density are investigated as functions of temperature at fixed value of chemical potential. The obtained results are in good agreement in comparison with other techniques. We conclude that the calculated effective potential successfully predicts the meson properties and thermodynamic properties at finite baryonic chemical potential.

M. Abu-Shady

2014-03-13

154

Temperature and precipitation trends and dryness\\/wetness pattern in the Zhujiang River Basin, South China, 1961–2007  

Microsoft Academic Search

Spatial and temporal characteristics of temperature and precipitation in the Zhujiang River Basin, South China, are analysed in order to identify tendencies in dryness and wetness. Trend tests are applied to daily temperature and precipitation data from 1961 to 2007 of 192 weather stations. Nine indicators are applied in order to detect cycles of dryness and wetness and are compared

Thomas Fischer; Marco Gemmer; Liu Lüliu; Su Buda

2011-01-01

155

D.A. Stone A.J. Weaver Factors contributing to diurnal temperature range trends in twentieth  

E-print Network

model repre- senting the atmosphere, ocean, sea ice, and land surface systems. Consistent with pastD.A. Stone Ã? A.J. Weaver Factors contributing to diurnal temperature range trends in twentieth temperature range (DTR) are examined in the late twentieth and the twenty-first centuries in a coupled climate

156

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

157

Flame temperature trends in reacting vanadium and tungsten ethoxide fluid sprays during CO2-laser pyrolysis  

NASA Astrophysics Data System (ADS)

We observe the "invisible-to-the-naked-eye" flames of tungsten and vanadium ethoxide aerosols when ignited at moderate laser excitation (0< P laser<70 W) by employing an IR thermo-graphic camera. No emission is seen in the visible range whether by the visible region cameras or by spectroscopy. The emissivity of the precursor solution measured was 0.80 and 0.75 for tungsten and vanadium ethoxide, respectively. The spectral emissivities of the tungsten and vanadium ethoxide flames measured using FTIR-spectrometer were used to calculate the pyrolysis flame temperature at various laser intensities and wavelengths. New energy balance equations have been derived—the transient temperature one extended from Haggerty-Cannon equation and the other based on standard resonance analysis. Fitting these models to experimental data reveals that only small amounts (1.33% and 4.32%, respectively) of the laser power are used in the pyrolysis of the precursor ethoxide aerosols into the desired oxide nanostructures. The low levels of specific heat capacity values obtained in these sprays suggest that these are electronic heat capacities rather than lattice heat capacities; enthalpies are also obtained. The experimental temperature-laser power trends observed were in agreement with previous findings from Tenegal et al. (Chem. Phys. Lett. 335:155, 2001). The damping coefficients, and hence the saturation intensities confirm that the vanadium containing precursor liquid is harder to dissociate into final products than the tungsten precursor as observed experimentally.

Mwakikunga, B. W.; Mudau, A. E.; Brink, N.; Willers, C. J.

2011-11-01

158

Testing linear gravity wave theory with simultaneous wind and temperature data from the mesosphere  

NASA Astrophysics Data System (ADS)

Linear gravity wave (GW) theory is tested on the basis of simultaneous measurements of horizontal winds from a medium frequency (MF) radar at Juliusruh (54.6°N, 13.4°E) and temperatures from combined Potassium (K) and Rayleigh-Mie-Raman (RMR) lidars at Kühlungsborn (54.1°N, 11.8°E). The applicability of linear GW theory to mesospheric observations is far from obvious given the fact that typically a whole spectrum of waves is observed which may interact non-linearly. Before analyzing our experimental dataset for its fit to expectations from linear GW theory, the chosen methodology is tested with model data from the Kühlungsborn Mechanistic general Circulation Model (KMCM). This model is a mechanistic general circulation model with high spatial resolution such that waves with horizontal wavelengths in excess of ˜350km are explicitly resolved yielding a semi-realistic wave motion field. This may be considered as a suitable test-bed for defining and optimizing wave analysis approaches. This effort reveals that Stokes parameters analysis of filtered time series of GW-induced wind and temperature fluctuations in comparison to wave amplitudes directly retrieved from the filtered time series allows us to demonstrate the validity of polarization relations based on linear wave theory. Indeed, applying the same methodology to the observations yields similarly conclusive results thus giving evidence for the applicability of linear wave theory to mesospheric observations after appropriate filtering. These investigations are complemented by a comparison of kinetic and potential energy per unit mass for model and measured data. This reveals that the ratio of kinetic and potential energy also roughly follows expectations from linear wave theory.

Placke, Manja; Hoffmann, Peter; Gerding, Michael; Becker, Erich; Rapp, Markus

2013-02-01

159

Continuing upward trend in Mt Read Huon pine ring widths - Temperature or divergence?  

NASA Astrophysics Data System (ADS)

To date, no attempt has been made to assess the presence or otherwise of the “Divergence Problem” (DP) in existing multi-millennial Southern Hemisphere tree-ring chronologies. We have updated the iconic Mt Read Huon pine chronology from Tasmania, southeastern Australia, to now include the warmest decade on record, AD 2000-2010, and used the Kalman Filter (KF) to examine it for signs of divergence against four different temperature series available for the region. Ring-width growth for the past two decades is statistically unprecedented for the past 1048 years. Although we have identified a decoupling between temperature and growth in the past two decades, the relationship between some of the temperature records and growth has varied over time since the start of instrumental records. Rather than the special case of ‘divergence’, we have identified a more general time-dependence between growth and temperature over the last 100 years. This time-dependence appears particularly problematic at interdecadal time scales. Due to the time-dependent relationships, and uncertainties related to the climate data, the use of any of the individual temperature series examined here potentially complicates temperature reconstruction. Some of the uncertainty in the climate data may be associated with changing climatic conditions, such as the intensification of the sub-tropical ridge (STR) and its impact on the frequency of anticyclonic conditions over the Mt Read site. Increased growth at the site, particularly in the last decade, over and above what would be expected based on a linear temperature model alone, may be consistent with a number of hypotheses. Existing uncertainties in the climate data need to be resolved and independent physiological information obtained before a range of hypotheses for this increased growth can be effectively evaluated.

Allen, K. J.; Cook, E. R.; Buckley, B. M.; Larsen, S. H.; Drew, D. M.; Downes, G. M.; Francey, R. J.; Peterson, M. J.; Baker, P. J.

2014-10-01

160

Liquid phase temperature determination in dense water sprays using linear Raman scattering.  

PubMed

Linear Raman scattering has been applied for the determination of the temperature of the liquid phase in water sprays under normal and superheated conditions. The envelope of the Raman OH-stretching vibration band of water is deconvoluted into five Gaussian peaks which can be assigned to five different intermolecular interactions (hydrogen bonding). The intensity of each of the peaks is a function of the temperature and the phase of the water under investigation. The interference of the Raman signals originating from the water vapor is eliminated from the Raman signals originating from the liquid water. Consequently the temperature of the liquid water droplets surrounded by water vapor is accessible which is favorable for the investigation of non-equilibrium sprays where the droplet temperature is different to the vapor temperature. PMID:24718172

Hankel, Robert Fabian; Günther, Astrid; Wirth, Karl-Ernst; Leipertz, Alfred; Braeuer, Andreas

2014-04-01

161

The linear thermal expansion of bulk nanocrystalline Al and SS304 at low temperature  

NASA Astrophysics Data System (ADS)

The linear thermal expansions (LTE) of bulk nanocrystalline (NC) Al, 304 stainless steel (SS304) and their conventional coarse-grained poly-crystalline counterparts (CCPC) were studied by the strain gage method in four directions within rolling plane (for bulk NC SS304 and Al) and one direction (for their CCPC) from liquid nitrogen temperature to 300 K. LTE of bulk NC Al and SS304 in four directions were equal to or less than those of their CCPC. This result was different from the fact that the smaller thermal expansions of many other bulk nanocrystalline materials were larger than those of their CCPC. We had to conclude that the less linear thermal expansions of bulk NC SS304 and Al were attributed to their larger defects at grain boundaries and residual strain. However, the larger linear thermal expansions of many other NC materials resulted from two factors.

Wang, S. G.; Huang, R. J.; Mei, Y.; Long, K.; Li, L. F.; Zhang, Z. D.

2011-07-01

162

On the Trend of the Annual Mean, Maximum, and Minimum Temperature and the Diurnal Temperature Range in the Armagh Observatory, Northern Ireland, Dataset, 1844 -2012  

NASA Technical Reports Server (NTRS)

Examined are the annual averages, 10-year moving averages, decadal averages, and sunspot cycle (SC) length averages of the mean, maximum, and minimum surface air temperatures and the diurnal temperature range (DTR) for the Armagh Observatory, Northern Ireland, during the interval 1844-2012. Strong upward trends are apparent in the Armagh surface-air temperatures (ASAT), while a strong downward trend is apparent in the DTR, especially when the ASAT data are averaged by decade or over individual SC lengths. The long-term decrease in the decadaland SC-averaged annual DTR occurs because the annual minimum temperatures have risen more quickly than the annual maximum temperatures. Estimates are given for the Armagh annual mean, maximum, and minimum temperatures and the DTR for the current decade (2010-2019) and SC24.

Wilson, Robert M.

2013-01-01

163

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

National Technical Information Service (NTIS)

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...

F. Yang, K. M. Lau

2004-01-01

164

Spatiotemporal analysis of temperature trends under climate change in the source region of the Yellow River, China  

NASA Astrophysics Data System (ADS)

Under global climate change, the change in temperature has greatly affected the hydrological processes and water resource security in the source region of the Yellow River, which is located in the Qinghai-Tibet Plateau and serves as a major source of domestic and agricultural water supply in the watershed. Multiple spatiotemporal analysis methods, including the S-mode empirical orthogonal function analysis, the inverse distance weighted interpolation, the weighted moving average method, and the Mann-Kendall test method were used to comprehensively analyze the temperatures of 14 meteorological stations at yearly and seasonal scales from 1961 to 2010. The results indicated that (1) general trends of temperature change have been rising, with an especially significant warming trend since the late 1990s; (2) in the last five decades, temperature trends in the study area underwent three stages, namely a cool stage (approximately 1961-1980), a fluctuating stage (approximately 1981-1997), and a warm stage (approximately 1998-2010); and (3) due to the combined effects of monsoons and geographic features, the source region could be divided into three zones according to the annual temperature variations: a low-value zone centered on Henan station in the northeastern edge; a high-value zone situated in the central, southern, and western area; and a transitional zone between the two zones mentioned above. This study is helpful for understanding temperature trends under climate change and can provide a basis for ecological protection.

Wang, Yuli; Wang, Xuan; Li, Chunhui; Wu, Feifei; Yang, Zhifeng

2014-02-01

165

Linear Gyrokinetic Simulations of Electrostatic Ion Temperature Gradient Driven Instability In a Toroidal Reverse Field Pinch  

NASA Astrophysics Data System (ADS)

We address linear Ion Temperature Gradient (ITG) driven micro-turbulence in a real RFP geometry using GYRO[1], a code extensively used for simulations of micro-instabilities in tokamak geometry. The parameters in the RFP suggest an ultra-low q, negative shear regime with average bad curvature that has been rarely investigated. We show that this regime has unique mode structure and scaling properties. The code GYRO has been modified to simulate ITG in a collisionless, linear, electrostatic limit. We compute the growth rate spectrum, and analyze its dependence on density and temperature scalelengths. We also make comparisons with simple calculations and potential relevance of the slab and toroidal branches. [1] J. Candy and R.E. Waltz, J. Comp. Phys. 186, 545 (2003)

Tangri, Varun; Terry, Paul; Waltz, R. W.

2009-05-01

166

The linear thermal expansion of bulk nanocrystalline Al and SS304 at low temperature  

Microsoft Academic Search

The linear thermal expansions (LTE) of bulk nanocrystalline (NC) Al, 304 stainless steel (SS304) and their conventional coarse-grained poly-crystalline counterparts (CCPC) were studied by the strain gage method in four directions within rolling plane (for bulk NC SS304 and Al) and one direction (for their CCPC) from liquid nitrogen temperature to 300 K. LTE of bulk NC Al and SS304

S. G. Wang; R. J. Huang; Y. Mei; K. Long; L. F. Li; Z. D. Zhang

2011-01-01

167

The linear thermal expansion of bulk nanocrystalline Al and SS304 at low temperature  

Microsoft Academic Search

The linear thermal expansions (LTE) of bulk nanocrystalline (NC) Al, 304 stainless steel (SS304) and their conventional coarse-grained poly-crystalline counterparts (CCPC) were studied by the strain gage method in four directions within rolling plane (for bulk NC SS304 and Al) and one direction (for their CCPC) from liquid nitrogen temperature to 300K. LTE of bulk NC Al and SS304 in

S. G. Wang; R. J. Huang; Y. Mei; K. Long; L. F. Li; Z. D. Zhang

2011-01-01

168

Temperature effects on the linear and nonlinear optical absorption coefficient in semi-parabolic quantum wells  

NASA Astrophysics Data System (ADS)

The effects of temperature on the linear and nonlinear optical absorption coeffic ient in semi-parabolic quantum wells are investigated. By the compact density matrix approach, analytical expressions for these optical properties are obtained. Numerical results are used for typical GaAs/AlxGa1-xAs semi-parabolic nanostructure system. In this paper we have presented the behavior of these optical properties as a function of photon energy and inc ident optical intensity considering the effect of temperature. Our results can make a significant contribution both in practical application and in theoretical research.

Kargar, Asghar; Keshavarz, Alireza

2012-09-01

169

Linear viscoelastic limits of asphalt concrete at low and intermediate temperatures  

NASA Astrophysics Data System (ADS)

The purpose of this dissertation is to demonstrate the hypothesis that a region at which the behavior of asphalt concrete can be represented as a linear viscoelastic material can be determined at low and intermediate temperatures considering the stresses and strains typically developed in the pavements under traffic loading. Six mixtures containing different aggregate gradations and nominal maximum aggregate sizes varying from 12.5 to 37.5 mm were used in this study. The asphalt binder grade was the same for all mixtures. The mixtures were compacted to 7 +/- 1% air voids, using the Superpave Gyratory Compactor. Tests were conducted at low temperatures (-20°C and -10°C), using the indirect tensile test machine, and at intermediate temperatures (4°C and 20°C), using the Superpave shear machine. To determine the linear viscoelastic range of asphalt concrete, a relaxation test for 150 s, followed by a creep test for another 150 s, was conducted at 150 and 200 microstrains (1 microstrain = 1 x 10-6), at -20°C, and at 150 and 300 microstrains, at -10°C. A creep test for 200 s, followed by a recovery test for another 200 s, was conducted at stress levels up to 800 kPa at 4°C and up to 500 kPa at 20°C. At -20°C and -10°C, the behavior of the mixtures was linear viscoelastic at 200 and 300 microstrains, respectively. At intermediate temperatures (4°C and 20°C), an envelope defining the linear and nonlinear region in terms of stress as a function of shear creep compliance was constructed for all the mixtures. For creep tests conducted at 20°C, it was discovered that the commonly used protocol to verify the proportionality condition of linear viscoelastic behavior was unable to detect the appearance of nonlinear behavior at certain imposed shear stress levels. Said nonlinear behavior was easily detected, however, when checking the satisfaction of the superposition condition. The envelope constructed for determining when the material becomes nonlinear should be valid for mixtures similar to the ones tested in this study. Different envelopes should be used in the case of mixtures containing a very soft or a very stiff polymer modified binder. At 4°C, the typical values of stresses and material properties of mixtures fell within the linear viscoelastic region, considering the typical shear creep compliance values at loading times and stresses experienced in the field. However, typical values at 20°C fell within a region in which some, but not all of the mixtures tested in this study behaved linearly. It is known that the behavior of asphalt concrete mixture changes from linear to nonlinear, depending on the temperature and loading conditions. However, this study is the first of its kind in which both the proportionality and the superposition condition were evaluated. The experimental design and the analysis procedures presented in this study can be applied to similar experiments that may be conducted in the future to evaluate linearity of different types of asphalt concrete mixtures.

Mehta, Yusuf A.

170

Stratospheric temperatures in Antarctic winter: Does the 40-year record confirm midlatitude trends in stratospheric water vapour?  

NASA Astrophysics Data System (ADS)

Water vapour is a potent greenhouse gas, and the observed increases in water vapour in the stratosphere act to cool it. Possible changes in stratospheric temperatures are important for future ozone loss because colder temperatures in the edge region of the Antarctic ozone hole act to increase polar stratospheric clouds there, and so delay recovery of the ozone hole. Trends in lower-stratospheric temperature within the core of the Antarctic vortex in winter should be a unique indicator of trends in stratospheric water vapour, because neither changes in CO2 nor in ozone have a large effect on temperature in the lower stratosphere in the dark. Here, measured stratospheric temperatures southward of 70°S in winter are presented and their quality and corrections discussed. The character and magnitude of the long-term changes at Halley (76°S) are similar from 100 to 70 hPa and at 50 hPa, whether corrected for sonde changes or not, and are also similar to those at other Antarctic sites. We found no significant trend in temperatures at Halley between 1960 and 2000, which is inconsistent with the change calculated from the trend in lower-stratospheric water vapour in northern hemisphere midlatitudes between 1960 and 2000. Over the shorter interval between 1980 and 2000 at Halley, the change in temperature was-1.8 ± 0.6 K, in agreement with the change calculated from the trend in stratospheric water vapour in northern hemisphere midlatitudes between 1980 and 2000. The differences between these periods are discussed in terms of: possible fortuitous agreement between 1980 and 2000; the poorer representation and quality of the measurements of stratospheric water vapour between 1960 and 1980; and a possible large variation in the rate of oxidation of CH4 to H2O in the upper stratosphere between 1960 and 1980. Such a variation in oxidation rate was observed by satellite between 1992 and 1999.

Roscoe, H. K.; Colwell, S. R.; Shanklin, J. D.

2003-04-01

171

Piezoresistive Sensitivity, Linearity and Resistance Time Drift of Polysilicon Nanofilms with Different Deposition Temperatures  

PubMed Central

Our previous research work indicated that highly boron doped polysilicon nanofilms (?100 nm in thickness) have higher gauge factor (the maximum is ?34 for 80 nm-thick films) and better temperature stability than common polysilicon films (? 200nm in thickness) at the same doping levels. Therefore, in order to further analyze the influence of deposition temperature on the film structure and piezoresistance performance, the piezoresistive sensitivity, piezoresistive linearity (PRL) and resistance time drift (RTD) of 80 nm-thick highly boron doped polysilicon nanofilms (PSNFs) with different deposition temperatures were studied here. The tunneling piezoresistive model was established to explain the relationship between the measured gauge factors (GFs) and deposition temperature. It was seen that the piezoresistance coefficient (PRC) of composite grain boundaries is higher than that of grains and the magnitude of GF is dependent on the resistivity of grain boundary (GB) barriers and the weight of the resistivity of composite GBs in the film resistivity. In the investigations on PRL and RTD, the interstitial-vacancy (IV) model was established to model GBs as the accumulation of IV pairs. And the recrystallization of metastable IV pairs caused by material deformation or current excitation is considered as the prime reason for piezoresistive nonlinearity (PRNL) and RTD. Finally, the optimal deposition temperature for the improvement of film performance and reliability is about 620 °C and the high temperature annealing is not very effective in improving the piezoresistive performance of PSNFs deposited at lower temperatures. PMID:22399960

Shi, Changzhi; Liu, Xiaowei; Chuai, Rongyan

2009-01-01

172

Decadal Trends and Variability in Special Sensor Microwave / Imager (SSM/I) Brightness Temperatures and Earth Incidence Angle  

NASA Astrophysics Data System (ADS)

The Goddard Satellite-based Surface Turbulent Fluxes (GSSTF) dataset is a valuable tool for monitoring air-sea fluxes over the global ocean. The most recently released version of GSSTF, Version 2b, uses Remote Sensing Systems (RSS) Version-6 Special Sensor Microwave / Imager (SSM/I) brightness temperature (TB) dataset in its production. Analysis of long-term trends from 1987 to 2008 in GSSTF showed a surprising result: while column-integrated water vapor has a small positive trend (less than 1%/decade), the lowest 500-m water vapor (WB) has a large negative trend (-3.4%/decade). Through collaboration between our two groups, we determined that the trends in WB are due to trends in the earth incidence angle (EIA) of SSM/I TB measurements. The effect of these EIA trends must be removed from TB to get accurate trends in WB. This presentation characterizes EIA trends and variability in the SSM/I dataset, and explains their effect on TB. The entire dataset is analyzed, including all six sensors operating from 1987-2009. The methodology used to calculate EIA is explained, which provides insight into the sources of EIA variability. The main source of variability is the change in altitude over an orbit, however this is modulated by the precession of perigee that varies with a four month period. The physical relationship between EIA and TB is explained with RSS radiative transfer model. The relationship is not constant, but depends on the meteorological conditions in the satellite footprint, which is the key difficulty in removing EIA effects. Since the SSM/I satellites are gradually falling over time, EIA has a trend of -0.14°/decade. This produces a -0.3 K/decade trend in vertical polarization TB. RSS has always handled EIA variations using its retrieval algorithms that are parameterized in terms of EIA. In order to use legacy algorithms that do not include EIA dependence (e.g., Schulz WB retrieval algorithm), an algorithm to normalize TB to a nominal EIA is derived and its accuracy is characterized. The algorithm performs very well in all meteorological conditions, and provides highly accurate decadal trends. The performance of the algorithm is assessed for WB retrievals. These retrievals are used by GSSTF in the calculation of latent heat flux. Before normalization, WB has a trend of -3.4%/decade, and the algorithm reduces this trend to -0.9%/decade.

Hilburn, K. A.; Shie, C.

2011-12-01

173

Long-term Temperature Trends in the Deep Waters of the Weddell Sea Robin Robertson*, Martin Visbeck, Arnold L. Gordon, and E. Fahrbach1  

E-print Network

of the WSBW in the central Weddell Sea observed by Fahrbach et al. [1998a], and to the surface ice temperatureLong-term Temperature Trends in the Deep Waters of the Weddell Sea Robin Robertson*, Martin Visbeck November 28, 2001 #12;Long-term Temperature Trends in the Deep Waters of the Weddell Sea 2 Abstract Warming

Robertson, Robin

174

Trends in extremes of temperature, dew point, and precipitation from long instrumental series from central Europe  

Microsoft Academic Search

For the analysis of trends in weather extremes, we introduce a diagnostic index variable, the exceedance product, which combines\\u000a intensity and frequency of extremes. We separate trends in higher moments from trends in mean or standard deviation and use\\u000a bootstrap resampling to evaluate statistical significances. The application of the concept of the exceedance product to daily\\u000a meteorological time series from

K. Kürbis; M. Mudelsee; G. Tetzlaff; R. Brázdil

2009-01-01

175

Elevation dependency of recent and future minimum surface air temperature trends in the Tibetan Plateau and its surroundings  

Microsoft Academic Search

Elevation dependency of climate change signals has been found over major mountain ranges such as the European Alps and the Rockies, as well as over the Tibetan Plateau. In this study we examined the temporal trends in monthly mean minimum temperatures from 116 weather stations in the eastern Tibetan Plateau and its vicinity during 1961–2006. We also analyzed projected climate

Xiaodong Liu; Zhigang Cheng; Libin Yan; Zhi-Yong Yin

2009-01-01

176

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

177

Non-local gyrokinetic model of linear ion-temperature-gradient modes  

SciTech Connect

The non-local properties of anomalous transport in fusion plasmas are still an elusive topic. In this work, a theory of non-local linear ion-temperature-gradient (ITG) drift modes while retaining non-adiabatic electrons and finite temperature gradients is presented, extending the previous work [S. Moradi et al., Phys. Plasmas 18, 062106 (2011)]. A dispersion relation is derived to quantify the effects on the eigenvalues of the unstable ion temperature gradient modes and non-adiabatic electrons on the order of the fractional velocity operator in the Fokker-Planck equation. By solving this relation for a given eigenvalue, it is shown that as the linear eigenvalues of the modes increase, the order of the fractional velocity derivative deviates from two and the resulting equilibrium probability density distribution of the plasma, i.e., the solution of the Fokker-Planck equation, deviates from a Maxwellian and becomes Levy distributed. The relative effect of the real frequency of the ITG mode on the deviation of the plasma from Maxwellian is larger than from the growth rate. As was shown previously the resulting Levy distribution of the plasma may in turn significantly alter the transport as well.

Moradi, S.; Anderson, J. [Department of Applied Physics, Nuclear Engineering, Chalmers University of Technology and Euratom-VR Association, Goeteborg (Sweden)

2012-08-15

178

Non-local gyrokinetic model of linear ion-temperature-gradient modes  

E-print Network

A theory of non-local linear ion-temperature-gradient (ITG) drift modes while retaining non-adiabatic electrons is presented, extending the previous work [S. Moradi, et al {\\em Phys. Plasmas} {\\bf 18}, 062106 (2011)]. A dispersion relation is derived to quantify the effects of the fractional velocity operator in the Fokker-Planck equation modified by temperature gradients and non-adiabatic electrons on the real frequency and growth rate. Solving the dispersion relation, it is shown here that as the plasma becomes more turbulent, it deviates from a Maxwellian distribution and becomes L\\'{e}vy distributed. The resulting L\\'{e}vy distribution of the plasma may thus significantly alter the transport. The relative effect of the fractional derivative is larger on the real frequency than on the growth rate of the ITG mode.

Sara Moradi; Johan Anderson; B. Weyssow

2012-01-12

179

Mesoscopic Aligned and Cu-Coordinated Surface Linear Polymerization at Low Temperature  

NASA Astrophysics Data System (ADS)

The on-surface synthesis of covalent organic aggregates and networks has received considerable attention. However, most of the polymerization reactions require high temperatures to overcome the activation barrier. We demonstrate a surface-coordinated linear polymerization, which occurred at 100 K and forms long chain that are well-organized into a ``circuit-board'' pattern on Cu(100) surface. This highly strained 1D conjugated polymer alters greatly the electronic structure compared to unperturbed polymer and it was investigated by electronic and vibrational spectroscopies, as well as ab initio calculations. More importantly, the processes of polymerization and depolymerization can be controlled locally at the nanoscale by a using a charged metal tip. This work thus demonstrates the feasibility of accessing and controlling chain-growth polymerization at low temperature that may lead to the bottom-up construction of sophisticated architectures for molecular nano-devices.

Li, Qing; Owens, Jonathan R.; Han, Chengbo; Fuentes-Cabrera, Miguel; Sumpter, Bobby G.; Lu, Wenchang; Bernholc, Jerry; Maksymovych, Petro; Meunier, Vincent; Pan, Minghu

2013-03-01

180

Infrared line cameras based on linear arrays for industrial temperature measurement  

NASA Astrophysics Data System (ADS)

The PYROLINE/ MikroLine cameras provide continuous, non-contact measurement of linear temperature distributions. Operation in conjunction with the IR_LINE software provides data recording, real-time graphical analysis, process integration and camera-control capabilities. One system is based on pyroelectric line sensors with either 128 or 256 elements, operating at frame rates of 128 and 544 Hz respectively. Temperatures between 0 and 1300DGRC are measurable in four distinct spectral ranges; 8-14micrometers for low temperatures, 3-5micrometers for medium temperatures, 4.8-5.2micrometers for glass-temperature applications and 1.4-1.8micrometers for high temperatures. A newly developed IR-line camera (HRP 250) based upon a thermoelectrically cooled, 160-element, PbSe detector array operating in the 3 - 5 micrometers spectral range permits the thermal gradients of fast moving targets to be measured in the range 50 - 180 degree(s)C at a maximum frequency of 18kHz. This special system was used to measure temperature distributions on rotating tires at velocities of more than 300 km/h (190 mph). A modified version of this device was used for real-time measurement of disk-brake rotors under load. Another line camera consisting a 256 element InGaAs array was developed for the spectral range of 1.4 - 1.8 micrometers to detect impurities of polypropylene and polyethylene in raw cotton at frequencies of 2.5 - 5 kHz.

Drogmoeller, Peter; Hofmann, Guenter; Budzier, Helmut; Reichardt, Thomas; Zimmerhackl, Manfred

2002-03-01

181

Predicting offshore temperatures in Monterey Bay based on coastal observations using linear forecast models  

NASA Astrophysics Data System (ADS)

The linear systems approach is used to forecast offshore near-surface and subsurface temperatures in Monterey Bay and further offshore based on coastal sea surface temperatures (SSTs) at Pacific Grove. SST from Pacific Grove provided the input to the system and the forecast parameters or outputs were temperature at 1 m and 100 m at the M1 buoy located 20 km from Pacific Grove near the center of Monterey Bay, and temperature at 1 m at the M2 buoy located 55 km from Pacific Grove. To forecast temperatures at the M1 and M2 buoys, Box-Jenkins, State-Space, ARX, and ARMAX models were employed. Model formulation, implementation, forecasting procedures, and methods of evaluation are presented. Seven and 30-day forecasts were routinely made for the daily observations although other forecast horizons were employed. For all models and variables, RMS differences between the forecasts and the observations increased rapidly between 1 and 15 days. Beyond about 30 days, RMS differences tended to remain almost constant with increasing forecast horizon. Overall, model forecasts were best for temperature at 100 m at the M1 buoy, due to the fact that temperature is well conserved at depth. Differences in performance between the models were small but the ARMAX model often produced forecasts that were slightly better than the rest, a result that we attribute to a more complete specification of the noise. Although the Box-Jenkins and State-Space models have the potential to produce better forecasts, because more terms must be specified to implement them, the opportunity to produce less-than-optimal results is also greater. Finally, because of seasonal changes in the circulation of Monterey Bay, it is possible that causality was violated, upon occasion, placing certain constraints on the results. Models based on the linear systems approach, where they can be implemented, could serve as a useful adjunct to hydrodynamic ocean circulation models by providing additional information for model initialization, evaluation, and data assimilation. Using the same approach, operational forecasts of the coastal circulation could be made by including forecast winds and the predicted tides as inputs, and CODAR-observed surface currents as the output. In a less glamorous but still useful role, they could be used to fill significant gaps in offshore records where data continuity and quality are important.

Breaker, Laurence C.; Brewster, Jodi K.

182

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

183

A new weighting function for estimating microwave sounding unit channel 4 temperature trends simulated by CMIP5 climate models  

NASA Astrophysics Data System (ADS)

A new static microwave sounding unit (MSU) channel 4 weighting function is obtained from using Coupled Model Inter-comparison Project, Phase 5 (CMIP5) historical multimodel simulations as inputs into the fast Radiative Transfer Model for TOVS (RTTOV v10). For the same CMIP5 model simulations, it is demonstrated that the computed MSU channel 4 brightness temperature (T4) trends in the lower stratosphere over both the globe and the tropics using the proposed weighting function are equivalent to those calculated by RTTOV, but show more cooling than those computed using the traditional UAH (University of Alabama at Huntsville) or RSS (Remote Sensing Systems in Santa Rosa, California) static weighting functions. The new static weighting function not only reduces the computational cost, but also reveals reasons why trends using a radiative transfer model are different from those using a traditional static weighting function. This study also shows that CMIP5 model simulated T4 trends using the traditional UAH or RSS static weighting functions show less cooling than satellite observations over the globe and the tropics. Although not completely removed, this difference can be reduced using the proposed weighting function to some extent, especially over the tropics. This work aims to explore the reasons for the trend differences and to see to what extent they are related to the inaccurate weighting functions. This would also help distinguish other sources for trend errors and thus better understand the climate change in the lower stratosphere.

Zhang, Xuanze; Zheng, Xiaogu; Yang, Chi; Luo, San

2013-05-01

184

Seasonal trends in air temperature and precipitation in IPCC AR4 GCM output for Kansas, USA: evaluation and implications  

E-print Network

production in the state. Future trends in precipitation and temperature will also be heavily influenced by changes in local land cover (Fed- dema et al., 2005b). Urban heat island affects and accel- erated runoff rates associated with urbanisation in eastern... is vitally important for understanding future global food and possibly fuel security. Understanding potential future impacts of greenhouse gas (GHG) emissions on the cli- mate of the mid-western United States is critical to under- standing how climate change...

Brunsell, Nathaniel A.; Jones, Aubrey R.; Feddema, Johannes J.

2009-01-08

185

Elevation-Dependent Temperature Trends in the Rocky Mountain Front Range: Changes over a 56- and 20-Year Record  

PubMed Central

Determining the magnitude of climate change patterns across elevational gradients is essential for an improved understanding of broader climate change patterns and for predicting hydrologic and ecosystem changes. We present temperature trends from five long-term weather stations along a 2077-meter elevational transect in the Rocky Mountain Front Range of Colorado, USA. These trends were measured over two time periods: a full 56-year record (1953–2008) and a shorter 20-year (1989–2008) record representing a period of widely reported accelerating change. The rate of change of biological indicators, season length and accumulated growing-degree days, were also measured over the 56 and 20-year records. Finally, we compared how well interpolated Parameter-elevation Regression on Independent Slopes Model (PRISM) datasets match the quality controlled and weather data from each station. Our results show that warming signals were strongest at mid-elevations over both temporal scales. Over the 56-year record, most sites show warming occurring largely through increases in maximum temperatures, while the 20-year record documents warming associated with increases in maximum temperatures at lower elevations and increases in minimum temperatures at higher elevations. Recent decades have also shown a shift from warming during springtime to warming in July and November. Warming along the gradient has contributed to increases in growing-degree days, although to differing degrees, over both temporal scales. However, the length of the growing season has remained unchanged. Finally, the actual and the PRISM interpolated yearly rates rarely showed strong correlations and suggest different warming and cooling trends at most sites. Interpretation of climate trends and their seasonal biases in the Rocky Mountain Front Range are dependent on both elevation and the temporal scale of analysis. Given mismatches between interpolated data and the directly measured station data, we caution against an over-reliance on interpolation methods for documenting local patterns of climatic change. PMID:22970205

McGuire, Chris R.; Nufio, Cesar R.; Bowers, M. Deane; Guralnick, Robert P.

2012-01-01

186

Binary homogeneous nucleation: Temperature and relative humidity fluctuations and non-linearity  

SciTech Connect

This report discusses binary homogeneous nucleation involving H{sub 2}SO{sub 4} and water vapor is thought to be the primary mechanism for new particle formation in the marine boundary layer. Temperature, relative humidity, and partial pressure of H{sub 2}SO{sub 4} vapor are the most important parameters in fixing the binary homogeneous nucleation rate in the H{sub 2}SO{sub 4}/H{sub 2}O system. The combination of thermodynamic calculations and laboratory experiments indicates that this rate varies roughly as the tenth power of the saturation ratio of H{sub 2}SO{sub 4} vapor. Furthermore, the vapor pressure of H{sub 2}SO{sub 4} is a function of temperature, and similar dependencies of the binary homogeneous nucleation rate on relative humidity can be noted as well. These factors thus introduce strong non-linearities into the system, and fluctuations of temperature, relative humidity, and H{sub 2}SO{sub 4} vapor concentrations about mean values may strongly influence the nucleation rate measured in the atmosphere.

Easter, R.C. [Pacific Northwest Lab., Richland, WA (United States); Peters, L.K. [Kentucky Univ., Lexington, KY (United States). Dept. of Chemical Engineering

1993-01-01

187

Binary homogeneous nucleation: Temperature and relative humidity fluctuations and non-linearity  

SciTech Connect

This report discusses binary homogeneous nucleation involving H[sub 2]SO[sub 4] and water vapor is thought to be the primary mechanism for new particle formation in the marine boundary layer. Temperature, relative humidity, and partial pressure of H[sub 2]SO[sub 4] vapor are the most important parameters in fixing the binary homogeneous nucleation rate in the H[sub 2]SO[sub 4]/H[sub 2]O system. The combination of thermodynamic calculations and laboratory experiments indicates that this rate varies roughly as the tenth power of the saturation ratio of H[sub 2]SO[sub 4] vapor. Furthermore, the vapor pressure of H[sub 2]SO[sub 4] is a function of temperature, and similar dependencies of the binary homogeneous nucleation rate on relative humidity can be noted as well. These factors thus introduce strong non-linearities into the system, and fluctuations of temperature, relative humidity, and H[sub 2]SO[sub 4] vapor concentrations about mean values may strongly influence the nucleation rate measured in the atmosphere.

Easter, R.C. (Pacific Northwest Lab., Richland, WA (United States)); Peters, L.K. (Kentucky Univ., Lexington, KY (United States). Dept. of Chemical Engineering)

1993-01-01

188

Long-term trends and changes of soil temperature of recent decade in the permafrost zone of Russia  

NASA Astrophysics Data System (ADS)

The northern regions of Russia have rich natural resources (oil, gas). In recent years in these areas are increasingly built engineering structure for oil and gas production and their transportation. Current global warming has a great influence on soil condition in the permafrost zone. This can lead to negative effects on buildings and infrastructure which are built on frozen soils. Changes of the soil state in area of permafrost demand serious studying. Next steps have been done for research of this problem: Part 1. a) The daily data set of soil temperature under natural surface at depths up to 320 cm at the Russian meteorological stations has been prepared. The earliest year of data set is 1963, the current version is ending in 2011 (660 stations of Russia). Quality control of original data was performed in creating this data set. b) The data set of computed depth of soil seasonal thawing at the Russian meteorological stations till 2011 has been prepared (107 stations with yearly depth of thawing). Part 2. Changes of soils' condition for the last five decades have been researched based on the prepared data sets. The change of mean annual soil temperature at depths has been researched and soil warming in the vast area for 1963 - 2010 has been shown, the great trends (0,2 ÷ 0,4°C /10 years) increase at 320 cm have been found in Western and Eastern Siberia, and the greatest trends (0,4 ÷ 0,5°C/10 years) are found in their south part. This creates favorable conditions for increase of seasonal thawing depth in a permafrost zone, especially in its south part. The map of average depth of soil seasonal thawing for the same period (1963-2010) was made. It showed that the greatest depths of thawing 300-400 cm were observed near the border of permafrost and the smallest depths 50-250 cm predominate in the area of continuous permafrost. Part 3. Global warming of climate was slowed down from the beginning of the XXI century as it is known from publications. Additional researches of soil temperature change in recent decade showed that positive trends of soil temperature for this decade were changed on negative trends (-0,2 ÷ -0,6°C/10 years) in the South and the southeast of Western Siberia. The most intensive decrease of soil temperature in this region is observed since 2007. Trends of the thawing depth for permafrost soils were obtained for 2001-2011. Greatest significant positive trends of thawing depth have been obtained in Eastern Siberia (3÷5 cm/year). However, spots with significant negative trends are obtained in central Yakutia, and also to the south of Lake Baikal and near the Kolyma River mouth. Conclusions: 1. Using the Russian daily data set of soil temperature at depths up to 320 cm for last 40-50 years, soil warming is shown over the vast territory of the Russia. Maximum trends at the 320 cm depth are found in the south part of Western and Eastern Siberia. 2. One of the impacts of the current climate changes is the general tendency for the increase in the seasonal thawing depth on the vast territory of Western and Eastern Siberia. 3. In recent decade the tendency of soil temperature decrease has been appeared in south part of Western Siberia near south border of permafrost also decrease of seasonal thawing depth has been appeared in some regions. The work was done with the financial support of RFBR (project 11-05-00691).

Sherstiukov, A.

2013-12-01

189

Global temperatures and sunspot numbers. Are they related? Yes, but non linearly. A reply to Gil-Alana et al. (2014)  

NASA Astrophysics Data System (ADS)

Recently Gil-Alana et al. (2014) compared the sunspot number record and the temperature record and found that they differ: the sunspot number record is characterized by a dominant 11-year cycle while the temperature record appears to be characterized by a “singularity” or “pole” in the spectral density function at the “zero” frequency. Consequently, they claimed that the two records are characterized by substantially different statistical fractional models and rejected the hypothesis that the Sun influences significantly global temperatures. I will show that: (1) the “singularity” or “pole” in the spectral density function of the global surface temperature at the “zero” frequency does not exist-the observed pattern derives from the post 1880 warming trend of the temperature signal and is a typical misinterpretation that discrete power spectra of non-stationary signals can suggest; (2) appropriate continuous periodograms clarify the issue and also show a signature of the 11-year solar cycle (amplitude ?0.1 °C), which since 1850 has an average period of about 10.4 year, and of many other natural oscillations; (3) the solar signature in the surface temperature record can be recognized only using specific techniques of analysis that take into account non-linearity and filtering of the multiple climate change contributions; (4) the post 1880-year temperature warming trend cannot be compared or studied against the sunspot record and its 11-year cycle, but requires solar proxy models showing short and long scale oscillations plus the contribution of anthropogenic forcings, as done in the literature. Multiple evidences suggest that global temperatures and sunspot numbers are quite related to each other at multiple time scales. Thus, they are characterized by cyclical fractional models. However, solar and climatic indexes are related to each other through complex and non-linear processes. Finally, I show that the prediction of a semi-empirical model for the global surface temperature based on astronomical oscillations and anthropogenic forcing proposed by Scafetta since 2009 has, up to date, been successful.

Scafetta, Nicola

2014-11-01

190

Electron Temperature Gradient Turbulence: Validation in the Columbia Linear Machine Experiments  

NASA Astrophysics Data System (ADS)

The electron temperature gradient (ETG) mode, which is a dominant mechanism for turbulent electron thermal transport in plasmas, is produced and verified by a recent experiment conducted in the Columbia linear machine[1]. They report modes at ˜0.3 - 0.5 ;MHz, with azimuthal wave numbers m˜14-16 and parallel wave number k˜0.003; cm-1. We study these results using a gyro-fluid simulation code DTRANS and a gyro-kinetic simulation code GTC[2]. The results show that in the linear phase, the dispersion relation is consistent with kinetic theory for a slab ETG model and the radial structure of the fluctuation agrees with the experiment. We also investigate the saturation of ETG mode using the ExB turbulent mixing and coupling to low frequency modes. It turns out that low frequency drift-ion acoustic waves as in [1] interact with high frequency ETG modes to extract energy and saturate the ETG fluctuations. [4pt] [1] X. Wei, V. Sokolov, and A. K. Sen, Physics of Plasmas 17, 042108(2010). [0pt] [2] I. Holod, W. L. Zhang, Y. Xiao, and Z. Lin, Physics of Plasmas 16, 122307(2009).

Fu, Xiangrong; Horton, Wendell; Sen, Amiya; Xiao, Yong; Lin, Zhihong

2010-11-01

191

Application of Linear Propagation of Errors to Fuel Rod Temperature and Stored Energy Calculations  

SciTech Connect

Linear propagatlon of errors evaluates modeling uncertainty by approximating a function of interest by first-order Taylor's series expansions and then approximating the variance of the function by the variance of the linear approximation. This report discusses uncertainty analysis for different nuclear fuel rod designs, the process of model validation, and the effect of cracked pellet fuel models upon temperabre uncertainty. Using a postulated power history, the uncertainty for the predicted thermal response of boiling water reactor (BWR) and pressurized water reactor (PWR} fuel rods was evaluated. Beginning-of-life (BOL) relative uncertainty for BWR and PWR fuel rods is approximately the same. while different end-of-fife {EOL} thermal response results in different EOL uncertainty. Determining the validity of modeling relative to reality is discussed in qualitative terms. Validity is dependent upon verifying that the code correctly implements the model and that satisfactory agreement is found between the model and measurements. Fuel modeling codes are now using cracked pellet fuel models, which result in decreased fuel surface temperature. Estimated stored energy is lowered; but its relative uncertainty is increased. In general, however, the absolute upper uncertainty bound for stored energy is lower for a cracked pellet model than for a solid pellet model.

Cunningham, M. E.; Olsen, A. R.; Lanning, D. D.; Willford, R. E.

1980-10-01

192

Experimental Verification of the Linear Theory for Stimulated Raman Scattering in High-Temperature Hohlraum Plasmas  

SciTech Connect

We show that the measured stimulated Raman scattering (SRS) in a large-scale high-temperature plasma scales strongly with the plasma density, increasing by an order of magnitude when the electron density is increased by 20%. This is consistent with linear theory in a uniform plasma and will set the limit on drive laser beam intensity for forthcoming ignition experiments at the National Ignition Facility. Control of SRS at laser intensities consistent with 285 eV ignition hohlraums are achieved by using polarization smoothing which increases the intensity threshold for the onset of SRS by 1.6 {+-} 0.2. These results were quantitatively predicted by full beam 3-dimensional numerical laser-plasma interaction simulations.

Froula, D H; Divol, L; London, R A; Berger, R L; Doppner, T; Meezan, N B; Ross, J S; Suter, L J; Sorce, C; Glenzer, S H

2009-04-22

193

Evolutionary trends in high temperature superconductivity. (Latest citations from the INSPEC database). Published Search  

SciTech Connect

The bibliography contains citations concerning experimental and theoretical studies of high temperature superconducting materials. Topics include critical temperatures, transition temperatures, superconducting niobium alloys and rare earth metals, superconducting structure stabilization, and magnetic superconductors. Fabrication and evaluation of high temperature superconducting devices and films are included. (Contains a minimum of 75 citations and includes a subject term index and title list.)

NONE

1995-01-01

194

Evolutionary trends in high temperature superconductivity. (Latest citations from the INSPEC database). Published Search  

SciTech Connect

The bibliography contains citations concerning experimental and theoretical studies of high temperature superconducting materials. Topics include critical temperatures, transition temperatures, superconducting niobium alloys and rare earth metals, superconducting structure stabilization, and magnetic superconductors. Fabrication and evaluation of high temperature superconducting devices and films are included. (Contains a minimum of 68 citations and includes a subject term index and title list.)

Not Available

1994-03-01

195

TEMPERATURE TRENDS AND THE DISTRIBUTION OF GROUNDFISH IN CONTINENTAL SHELF WATERS, NOVA SCOTIA TO LONG ISLAND  

E-print Network

conditions than by temperature. An alternation in sea-surface temperature has been observed at Atlantic coast in sea-surface temperature, the 1969 annual mean being only slightly lower than the long-term mean and cooling. In Figure 2 seasonal sea-surface-temperature curves at BoothbilY Harbor based on monthly mean

196

Estimation of the Impact of Land-Surface Forcing on Temperature Trends in Eastern United States  

E-print Network

). In this approach they took advantage of the property that the NCEP/NCAR Reanalysis is sensitive to atmospheric, agriculture and aerosol effects. In this paper we extend and slightly correct the computations performed by KC in a spurious jump in the climatology, and hence in artificial trends. Instead of putting 1979 in the non

Maryland at College Park, University of

197

Linear relation between T H (homogeneous ice nucleation temperature) and T m (melting temperature) for aqueous solutions of sucrose, trehalose, and maltose  

Microsoft Academic Search

Homogeneous ice nucleation temperatures (THs) of aqueous sucrose, trehalose, and maltose solutions were measured together with melting temperatures (Tms). It is shown that there is a linear relation between TH and Tm for these solutions. Almost identical supercooling behavior is observed for these aqueous disaccharide solutions.

Hitoshi Kanno; Makoto Soga; Kazuhito Kajiwara

2007-01-01

198

A New Perspective on Recent Global Warming: Asymmetric Trends of Daily Maximum and Minimum Temperature  

Microsoft Academic Search

Monthly mean maximum and minimum temperatures for over 50% (10%) of the Northern (Southern) Hemisphere landmass, accounting for 37% of the global landmass, indicate that the rise of the minimum temperature has occurred at a rate three times that of the maximum temperature during the period 1951-90 (0.84°C versus 0.28°C). The decrease of the diurnal temperature range is approximately equal

Philip D. Jones; Richard W. Knight; George Kukla; Neil Plummer; Vyacheslav Razuvayev; Kevin P. Gallo; Janette Lindseay; Robert J. Charlson; Thomas C. Peterson

1993-01-01

199

Long-Term Temperature Trends and Tree Growth in the Taymir Region of Northern Siberia  

E-print Network

by the widths of their annual rings, generally forming a wider ring in warm years and a more narrow ring in cold- struct May­September mean temperatures for the past four cen- turies. These warm-season temperatures correlate with annual temperatures and indicate unusual warming in the 20th century. However

200

Secular temperature trends for the southern Rocky Mountains over the last five centuries  

NASA Astrophysics Data System (ADS)

Pre-instrumental surface temperature variability in the Southwestern United States has traditionally been reconstructed using variations in the annual ring widths of high altitude trees that live near a growth-limiting isotherm. A number of studies have suggested that the response of some trees to temperature variations is non-stationary, warranting the development of alternative approaches towards reconstructing past regional temperature variability. Here we present a five-century temperature reconstruction for a high-altitude site in the Rocky Mountains derived from the oxygen isotopic composition of cellulose (?18Oc) from Bristlecone Pine trees. The record is independent of the co-located growth-based reconstruction while providing the same temporal resolution and absolute age constraints. The empirical correlation between ?18Oc and instrumental temperatures is used to produce a temperature transfer function. A forward-model for cellulose isotope variations, driven by meteorological data and output from an isotope-enabled General Circulation Model, is used to evaluate the processes that propagate the temperature signal to the proxy. The cellulose record documents persistent multidecadal variations in ?18Oc that are attributable to temperature shifts on the order of 1°C but no sustained monotonic rise in temperature or a step-like increase since the late 19th century. The isotope-based temperature history is consistent with both regional wood density-based temperature estimates and some sparse early instrumental records.

Berkelhammer, M.; Stott, L. D.

2012-09-01

201

A Statistical Framework for Calculating and Assessing Compositional Linear Trends Within Fault Zones: A Case Study of the NE Block of the Clark Segment, San Jacinto Fault, California, USA  

NASA Astrophysics Data System (ADS)

Utilizing chemical data derived from the various fault zone architectural components of the Clark strand of the San Jacinto fault, southern California, USA, we apply for the first time non-central principal component analysis to calculate a compositional linear trend within molar A-CN-K space. In this procedure A-CN-K are calculated as the molar proportions of Al2O3 (A), CaO* + Na2O (CN), and K2O (K) in the sum of molar Al2O3, Na2O, CaO*, and K2O. CaO* is the molar CaO after correction for apatite. We then derive translational invariant chemical alteration intensity factors, t, for each architectural component through orthogonal projection of analyzed samples onto the compositional linear trend. The chemical alteration intensity factor t determines the relative change in composition compared to the original state (i.e., the composition of the altered wall rocks). It is dependent on the degree of intensity to which the process or processes responsible for the change in composition of each architectural component has been active. These processes include shearing, fragmentation, fluid flow, and generation of frictional heat. Non-central principal component analysis indicates that principal component 1 explains 99.7 % of the spread of A-CN-K data about the calculated compositional linear trend (i.e., the variance). The significance level for the overall one-way analysis of variance (ANOVA) is 0.0001. Such a result indicates that at least one significant difference across the group of means of t values is different at the 95 % confidence level. Following completion of the overall one-way ANOVA, the difference in means t test indicated that the mean of the t values for the fault core are different than the means obtained from the transition and damage zones. In contrast, at the 95 % confidence level, the means of the t values for the transition and damage zones are not statistically distinguishable. The results of XRD work completed during this study revealed that the <2 µm fraction is composed primarily of illite/smectite with ~15 % illite in the damage zone, of illite/smectite with ~30 % illite in the transition zone, and of discreet illite with very minor smectite in the fault core. These changes parallel the increasing values of the chemical alteration intensity factors (i.e., t). Based on the above results, it is speculated that when fault zones are derived from tonalitic wall rocks at depths of ~400 ± 100 m, the onset of the illite/smectite to illite conversion will occur when t values exceed 0.20 ± 0.12, the average chemical alteration intensity factor calculated for the transition zone. Under such conditions during repeated rupturing events, frictional heat is produced and acidic fluids with elevated temperatures (? ~125 °C) are flushed through the fault core. Over time, the combination of shearing, fragmentation, and frictionally elevated temperatures eventually overcomes the kinetic barrier for the illite/smectite to illite transition. Such settings and processes are unique to fault zones, and as a result, they represent an underappreciated setting for the development of illite from illite/smectite. The success of non-central principal component analysis in this environment offers the first statistically rigorous methodology for establishing the existence of compositional linear trends in fault zones. This method also derives quantifiable alteration intensity factors that could potentially be used to compare the intensity of alteration at different segments of a fault, as well as offer a foundation to interpret the potential driving forces for said alteration and differences therein.

Rockwell, Brian G.; Girty, Gary H.; Rockwell, Thomas K.

2014-05-01

202

Technology trends in high temperature pressure transducers: The impact of micromachining  

NASA Technical Reports Server (NTRS)

This paper discusses the implications of micromachining technology on the development of high temperature pressure transducers. The introduction puts forth the thesis that micromachining will be the technology of choice for the next generation of extended temperature range pressure transducers. The term micromachining is defined, the technology is discussed and examples are presented. Several technologies for high temperature pressure transducers are discussed, including silicon on insulator, capacitive, optical, and vibrating element. Specific conclusions are presented along with recommendations for development of the technology.

Mallon, Joseph R., Jr.

1992-01-01

203

Uncertainty estimation of the global temperature trends for multiple radiosondes, reanalyses, and CMIP3/IPCC climate model simulations  

NASA Astrophysics Data System (ADS)

Based on three groups of datasets that include radiosondes, reanalyses, and climate model simulations (e.g., Coupled Model Intercomparison Project, CMIP3) from 1979 to 2008, the interannual variability, global temperature trends, and their uncertainty using ensemble spread among intra-group and inter-group datasets have been discussed. The results show that the interannual temperature variability increased from the troposphere to stratosphere, and the maximum occurs around 50 hPa. The CMIP3 climate models have the largest discrepancy in the stratosphere. The intra-group correlations at 500 hPa generally show high similarity within each data group while the inter-group correlations between reanalyses and the CMIP3 climate model simulations indicate lesser similarity. In contrast, the inter-group correlation at 50 hPa is improved except with the Japanese 25-year Reanalysis Project (JRA-25) dataset, and the Twentieth Century Reanalysis (20CR) reanalysis shows a weak cross correlation. The global temperature trends are highly dependent on the individual data sources. Compared to the radiosondes, the reanalyses show a large ensemble spread of trends in the stratosphere, and the CMIP3 climate model simulations have a large ensemble spread in the height of the crossover point where tropospheric warming changes into stratospheric cooling. The largest ensemble spread among the reanalyses in the stratosphere is mainly from the large discrepancy in the JRA-25 reanalysis after 1998 and a relatively weak anomaly in the 20CR before 1986. The largest ensemble spread among the CMIP3 climate models in the troposphere is related to the influence of both volcanic eruptions and El Niño/La Niña-Southern Oscillation events. The strong anomalies corresponding to the volcanic eruptions of El Chichon in 1982 and Mt Pinatubo in 1991 are clearly identified in the stratosphere. These volcanic eruptions reduced the warming in the troposphere and strengthened the cooling in the stratosphere during the most recent 30 years.

Xu, Jianjun; Powell, Alfred M.

2012-05-01

204

The spin temperature of NH3 in Comet C/1999S4 (LINEAR).  

PubMed

A high-dispersion spectrum of Comet C/1999S4 (LINEAR) was obtained in the optical region with the high-dispersion spectrograph on the Subaru telescope when the comet was 0.863 astronomical units from the Sun before its disintegration. We obtained high signal-to-noise ratio emission lines of the cometary NH2 bands from which an ortho-to-para ratio (OPR) of 3.33 +/- 0.07 was derived on the basis of a fluorescence excitation model. Assuming that cometary NH2 mainly originates from ammonia through photodissociation, the derived OPR of NH2 molecules should reflect that of ammonia, which provides information on the environment of molecular formation or condensation and of the thermal history of cometary ices. Assuming that the OPR of ammonia in comets was unchanged in the nucleus, the derived spin temperature of ammonia (28 +/- 2 kelvin) suggests that a formation region of the cometary ammonia ice was between the orbit of Saturn and that of Uranus in the solar nebula. PMID:11691989

Kawakita, H; Watanabe, J; Ando, H; Aoki, W; Fuse, T; Honda, S; Izumiura, H; Kajino, T; Kambe, E; Kawanomoto, S; Noguchi, K; Okita, K; Sadakane, K; Sato, B; Takada-Hidai, M; Takeda, Y; Usuda, T; Watanabe, E; Yoshida, M

2001-11-01

205

Hemispheric surface air temperature variations: Recent trends and an uptate to 1987  

Microsoft Academic Search

The hemispheric mean land-surface air temperature series developed for both hemispheres by Jones et al. are updated through 1987. The global temperature estimate for 1987 is the third warmest on record, 1858--1987. Recent warming over the last 20 years (1967--86) is shown to be centered on middle latitude belts in both hemispheres.

P. D. Jones

1988-01-01

206

GLOBAL CORAL REEF BLEACHING AND SEA SURFACE TEMPERATURE TRENDS FROM SATELLITE-DERIVED HOTSPOT ANALYSIS  

Microsoft Academic Search

Coral reefs are among the first ecosystems threatened by global climate change: since 1982, repeated episodes of high sea temperature and large-scale bleaching stress have imposed accelerating and unprecedented morbidity and mortality in coral reefs, affecting even the most remote areas unstressed by direct human impacts. Analyses of global satellite-derived sea surface temperature anomalies and coral reef bleaching reports since

Thomas J. F. Goreau; Raymond L. Hayes

2005-01-01

207

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

208

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

209

The signature of ozone depletion on tropical temperature trends, as revealed by their seasonal cycle in model integrations with single forcings  

E-print Network

[1] The effect of ozone depletion on temperature trends in the tropical lower stratosphere is explored with an atmospheric general circulation model, and directly contrasted to the effect of increased greenhouse gases and ...

Polvani, Lorenzo M.

210

Trends in the Surface Meridional Temperature Alix I. Gitelman a , James S. Risbey b , Robert E. Kass a , and Richard D. Rosen c  

E-print Network

Trends in the Surface Meridional Temperature Gradient Alix I. Gitelman a , James S. Risbey b's climate. Defining an MTG index here as the difference in surface temperature between the 30 ffi --35 ffi N). In addition, one set of climate model simulations suggests a global average surface temperature difference

211

Trend or jump in recent surface air temperature time series in the Balkans?  

NASA Astrophysics Data System (ADS)

Changes in the mean annual air temperature measured at 67 meteorological stations in the Balkans during the last 48 (from 1961 to 2008) to 158 (from 1851 to 2008) years were investigated. This presentation is an attempt to show variability of regional climate using available relatively long-term time series of mean annual air temperature. The problem of causes (anthropogenic or natural) of the air temperature increase in the analysed region will not be discussed. The main purpose is to analyse records of air temperature during the 20th century in order to identify timing and magnitude of increase of air temperature observed in last twentieth years. Methods of rescaled adjusted partial sums (RAPS), regression and correlation analyses as well as F- and t-tests are used in order to describe changes in air temperature regimes. The analyses indicated that the most frequently statistically significant changes started in 1988 (at 34 gauging station or 50.7 %) and in 1992 (at 16 gauging station or 23.9 %). It was calculated that the increases of average mean annual air temperatures in period before and after warming is 0.807 °C ranging from the minimum value of -0.11 °C (decreasing) to the maximum value of 1.56 °C (increasing).

Bonacci, Ognjen

2010-05-01

212

Trend analysis of extreme climate indices using simulated temperature and precipitation time series for the Carpathian basin  

NASA Astrophysics Data System (ADS)

Global warming may be recognized both in shifts of regional mean climate, and also, in the frequency and intensity changes of different climate extremes. Several climate extreme indices are analyzed and compared for the Carpathian basin (located in Central/Eastern Europe) following the guidelines suggested by the joint WMO-CCl/CLIVAR Working Group on climate change detection. Our statistical trend analysis includes the evaluation of several extreme temperature and precipitation indices using different threshold values. In order to evaluate the expected trends (by 2071-2100 relative to the 1961-1990 reference period) in the Carpathian basin, daily values of meteorological variables are obtained from the outputs of various regional climate model (RCM) experiments accomplished in the frame of the completed EU-project PRUDENCE (Prediction of Regional scenarios and Uncertainties for Defining EuropeaN Climate change risks and Effects). Horizontal resolution of the applied RCMs is 50 km. Two emission scenarios (A2 and B2) are used to compare past and future simulated values of the extreme climate indices for the Carpathian basin. Furthermore, fine-resolution climate experiments of two additional RCMs adapted and run at the Department of Meteorology, Eotvos Lorand University are used to extend the trend analysis of climate extremes for the Carpathian basin. (1) Model PRECIS (run at 25 km horizontal resolution) was developed at the UK Met Office, Hadley Centre, and it uses the boundary conditions from the HadCM3 GCM. (2) Model RegCM3 (run at 10 km horizontal resolution) was developed by Giorgi et al. and it is available from the ICTP (International Centre for Theoretical Physics). Analysis of the simulated daily temperature datasets suggests that the detected regional warming is expected to continue in the 21st century. Cold temperature extremes are projected to decrease while warm extremes tend to increase significantly. Expected changes of annual precipitation indices are small, but generally consistent with the detected trends of the 20th century. Based on the simulations, extreme precipitation events are expected to become more intense and more frequent in winter, while a general decrease of extreme precipitation indices is expected in summer.

Pongracz, R.; Bartholy, J.; Szabo, P.; Kovacs, G.

2009-09-01

213

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

214

Influences of Temperature and Precipitation Changes on Model-Simulated Monthly Snowfall Trends  

Microsoft Academic Search

Projections of the Earth's climate for the 21st century indicate that both globally-averaged temperature and globally-averaged precipitation will increase. These changes, however, have a competing effect on the potential change in snowfall for the coming century. Using simulations performed with the GFDL CM2.1 coupled atmosphere-ocean global climate model, the individual effects of temperature changes and precipitation changes are isolated and

J. P. Krasting; A. J. Broccoli

2006-01-01

215

Facies-related trends of rock thermal conductivity and the impact on temperature prognosis for geothermal target reservoirs  

NASA Astrophysics Data System (ADS)

To characterize the temperature regime in a sedimentary basin, knowledge of the rock thermal conductivity (TC) is vital. This also pertains to temperature prognosis for geothermal target reservoirs based on modelling, which in turn requires an assignment of TC values to model units. Those model units can consist of single lithotypes but are mostly composed of different lithotypes or different geological formations. It is common procedure in numerical modelling to use one single (average) value for a certain model unit only, i.e., ignoring spatial TC variations owing to changes in lithofacies. This study addresses the shortcomings of the common parameterization of geothermal models with such TC averages. We show for two different geological settings, and exemplarily for specific geological formations, how strong geological-facies changes across a sedimentary basin can affect the TC. Especially for sedimentary basins of heterogeneous composition, the facies-related trends of TC may be significant. We demonstrate the impact of such TC variations on temperature by calculation of temperature profiles for a synthetic stratigraphic profile, considering different probable average in-situ TC values for the various stratigraphic units. This approach results in a broad envelope of temperature profiles. Considering the inner 50 % interval of the envelope, the uncertainty in depth estimation for a 70°C subsurface-temperature amounts to approximately 500 m. Likewise, the uncertainty for a 120°C temperature is on the order of 1,000 m. Thus, the use of average formation TCs for a large sedimentary basin may cause big errors in temperature-depth predictions that affect the search for geothermal prospects and, consequently, may be of serious economic impact. A detailed analysis of facies types, related lithotype changes, and associated variations of thermal parameters is, therefore, indispensable to improve the understanding of the thermal pattern in a sedimentary basin.

Schütz, Felina; Fuchs, Sven; Förster, Andrea; Förster, Hans-Jürgen

2013-04-01

216

Oxygen-isotope trends and seawater temperature changes across the Late Cambrian Steptoean positive carbon-isotope excursion (SPICE event)  

USGS Publications Warehouse

The globally recognized Late Cambrian Steptoean positive C-isotope excursion (SPICE) is characterized by a 3???-5??? positive ??13C shift spanning <4 m.y. Existing hypotheses suggest that the SPICE represents a widespread ocean anoxic event leading to enhanced burial/preservation of organic matter (Corg) and pyrite. We analyzed ??18O values of apatitic inarticulate brachiopods from three Upper Cambrian successions across Laurentia to evaluate paleotemperatures during the SPICE. ??18O values range from ~12.5??? to 16.5???. Estimated seawater temperatures associated with the SPICE are unreasonably warm, suggesting that the brachiopod ??18O values were altered during early diagenesis. Despite this, all three localities show similar trends with respect to the SPICE ??13C curve, suggesting that the brachiopod apatite preserves a record of relative ??18O and temperature changes. The trends include relatively high ??18O values at the onset of the SPICE, decreasing and lowest values during the main event, and an increase in values at the end of the event. The higher ??18O values during the global extinction at the onset of the SPICE suggests seawater cooling and supports earlier hypotheses of upwelling of cool waters onto the shallow shelf. Decreasing and low ??18O values coincident with the rising limb of the SPICE support the hypothesis that seawater warming and associated reduced thermohaline circulation rates contributed to decreased dissolved O2 concentrations, which enhanced the preservation/burial of Corg causing the positive ??13C shift. ?? 2011 Geological Society of America.

Elrick, M.; Rieboldt, S.; Saltzman, M.; McKay, R. M.

2011-01-01

217

Regional 20th Century Temperature Trends from Radiosondes and Reanalyses in the Arctic (60°N-90°N)  

NASA Astrophysics Data System (ADS)

We compare seasonal 20th century atmospheric temperature trends in the Arctic (60°N-90°N) from radiosonde observations (CHUAN, HadAT, IUK, RAOBCORE/RICH, RATPAC) and reanalyses (ERA-40, NCEP/NCAR (NNR), Twentieth Century reanalysis (20CR), CFSR, ERA-Interim, MERRA). Large differences are found between the magnitudes, vertical profiles of the temperature trends (even for time periods > 3 decades), and chronological sequences of bidecadal, regional warming and cooling periods in the reanalyses. Long term zonal mean vertical trend profiles from CHUAN and from the reanalyses reaching back to the time before the satellite era show an amplification of the tropospheric warming towards the surface in all seasons except in JJA for the periods 1901-99, 1948-99 and 1957-99. In 20CR, a very strong 20th century cooling trend compared to the other datasets is found between 150 and 200 hPa. The agreement of the vertical structure and temporal behaviour of regional, bidecadal trends in the long reanalyses for 11 regions in the Arctic with CHUAN is best on average for ERA-40, followed by a less good agreement with trends from NNR (especially vertical structure) and 20CR (vertical structure and temporal behaviour). ERA-40 performs best for the NE Atlantic, Karelia, the SE Canadian Arctic, Alaska, and Central Siberia, and less favourably in the NW Canadian Arctic, E Siberia, W Siberia, and Novaya Zemlya. NNR agreement with CHUAN is significantly worse than in ERA-40 for the NE Atlantic, SE Canadian Arctic, SW Central Siberia, and E Central Siberia. 20CR performance is generally worse than that of ERA-40 and NNR, particularly for Karelia, the SE Canadian Arctic, Novaya Zemlya, W Siberia, and Central Siberia. For the more recent but shorter reanalyses, the internal agreement is generally very high, and results are close to CHUAN, ERA-40 and NNR. A comparison of CHUAN with the other radiosonde datasets is only possible for Alaska, E Central Siberia, NE Atlantic and NE Central Siberia (only HadAT and IUK), E Siberia and Novaya Zemlya (only HadAT), and Karelia, SW Central Siberia and W Siberia (all except RATPAC). For the period of overlap (1951-99) the agreement is reasonable with respect to the general picture. However, some disagreement on the trend sign can be seen a) for Alaska during DJF 1961-80 with HadAT and IUK, b) for E Central Siberia during MAM 1971-90 and 1980-99 with HadAT and during DJF 1980-99, MAM 1971-99 and SON 1961-80 with IUK, c) for Karelia during MAM/JJA 1961-80 with RAOBCORE/RICH (JJA also with HadAT and IUK), d) for NE Central Siberia during DJF 1961-80 with HadAT, e) for Novaya Zemlya during DJF1961-80 with HadAT, f) for SW Central Siberia during SON 1980-99 with RAOBCORE/RICH, g) for W Siberia during DJF/MAM 1961-80 with RAOBCORE/RICH, HadAT and IUK.

Stickler, Alexander; Brönnimann, Stefan

2013-04-01

218

The temperature dependence of vibronic lineshapes: Linear electron-phonon coupling.  

PubMed

We calculate the effect of a linear electron-phonon coupling on vibronic transitions of dye molecules of arbitrary complexity. With the assumption of known vibronic frequencies (for instance from quantum-chemical calculations), we give expressions for the absorption or emission lineshapes in a second-order cumulant expansion. We show that the results coincide with those obtained from generalized Redfield theory if one uses the time-local version of the theory and applies the secular approximation. Furthermore, the theory allows to go beyond the Huang-Rhys approximation and can be used to incorporate Dushinsky effects in the treatment of the temperature dependence of optical spectra. We consider both, a pure electron-phonon coupling independent of the molecular vibrations and a coupling bilinear in the molecular vibrational modes and the phonon coordinates. We discuss the behavior of the vibronic density of states for various models for the spectral density representing the coupling of the vibronic system to the harmonic bath. We recover some of the results that have been derived earlier for the spin-boson model and we show that the behavior of the spectral density at low frequencies determines the dominant features of the spectra. In case of the bilinear coupling between the molecular vibrations and the phonons we give analytical expressions for different spectral densities. The spectra are reminiscent of those obtained from the well known Brownian oscillator model and one finds a zero-phonon line and phonon-side bands located at vibrational frequencies of the dye. The intensity of the phonon-side bands diminishes with increasing vibrational frequencies and with decreasing coupling strength (Huang-Rhys factor). It vanishes completely in the Markovian limit where only a Lorentzian zero-phonon line is observed. PMID:25338884

Roos, Claudia; Köhn, Andreas; Gauss, Jürgen; Diezemann, Gregor

2014-10-21

219

The temperature dependence of vibronic lineshapes: Linear electron-phonon coupling  

NASA Astrophysics Data System (ADS)

We calculate the effect of a linear electron-phonon coupling on vibronic transitions of dye molecules of arbitrary complexity. With the assumption of known vibronic frequencies (for instance from quantum-chemical calculations), we give expressions for the absorption or emission lineshapes in a second-order cumulant expansion. We show that the results coincide with those obtained from generalized Redfield theory if one uses the time-local version of the theory and applies the secular approximation. Furthermore, the theory allows to go beyond the Huang-Rhys approximation and can be used to incorporate Dushinsky effects in the treatment of the temperature dependence of optical spectra. We consider both, a pure electron-phonon coupling independent of the molecular vibrations and a coupling bilinear in the molecular vibrational modes and the phonon coordinates. We discuss the behavior of the vibronic density of states for various models for the spectral density representing the coupling of the vibronic system to the harmonic bath. We recover some of the results that have been derived earlier for the spin-boson model and we show that the behavior of the spectral density at low frequencies determines the dominant features of the spectra. In case of the bilinear coupling between the molecular vibrations and the phonons we give analytical expressions for different spectral densities. The spectra are reminiscent of those obtained from the well known Brownian oscillator model and one finds a zero-phonon line and phonon-side bands located at vibrational frequencies of the dye. The intensity of the phonon-side bands diminishes with increasing vibrational frequencies and with decreasing coupling strength (Huang-Rhys factor). It vanishes completely in the Markovian limit where only a Lorentzian zero-phonon line is observed.

Roos, Claudia; Köhn, Andreas; Gauss, Jürgen; Diezemann, Gregor

2014-10-01

220

A comparison of linear and neural network ARX models applied to a prediction of the indoor temperature of a building  

Microsoft Academic Search

A neural network auto regressive with exogenous input (NNARX) model is used to predict the indoor temperature of a residential building. Firstly, the optimal regressor of a linear ARX model is identified by minimising Akaike’s final prediction error (FPE). This regressor is then used as the input vector of a fully connected feedforward neural network with one hidden layer of

A. Mechaqrane; M. Zouak

2004-01-01

221

Prediction of room temperature and relative humidity by autoregressive linear and nonlinear neural network models for an open office  

Microsoft Academic Search

In this study, a linear parametric autoregressive model with external inputs (ARX) and a neural network-based nonlinear autoregressive model with external inputs (NNARX) are developed to predict the thermal behaviour of an open office in a modern building. External and internal climate data recorded over three months were used to build and validate models for predicting dry bulb temperature and

G. Mustafaraj; G. Lowry; J. Chen

2011-01-01

222

Non-linear Temperature Oscillations in the Plasma Centre on Tore Supra and their Interplay with MHD  

E-print Network

Non-linear Temperature Oscillations in the Plasma Centre on Tore Supra and their Interplay with MHD not have a helical structure and, therefore, cannot be ascribed as MHD phenomena. The most probable behaviour. Recent experimental results in which the O-regime co-exists with MHD modes will be presented

Paris-Sud XI, Université de

223

Mapping seasonal trends of electron temperature in the topside ionosphere based on DEMETER data  

NASA Astrophysics Data System (ADS)

The diurnal, seasonal and latitudinal variations of the electron temperature in the Earth's topside ionosphere during relatively low solar activity period of 2005 - 2008 are investigated. In order to examine seasonal variations and morphology of the topside ionospheric plasma temperature, CNES micro-satellite DEMETER ISL data are used. Presented study is oriented on the dataset gathered in 2005 and 2008. Within conducted analysis, global maps of electron temperature for months of equinoxes and solstices have been developed. Furthermore, simultaneous studies on two-dimensional time series based on DEMETER measurements and predictions obtained with the IRI-2012 model supply examination of the topside ionosphere during recent deep solar minimum. Comparison with the IRI-2012 model reveals discrepancies between data and prediction, that are especially prominent during the periods of very low solar activity.

Slominska, Ewa; Rothkaehl, Hanna

2013-07-01

224

Trends in high temperature materials technology for advanced aircraft turbine engines  

NASA Technical Reports Server (NTRS)

The utilization of high temperature materials for turbine blades, disks, vanes, and combustors is reviewed. The use of directionally solidified eutectic alloys and of metal fiber reinforced superalloys as turbine blade materials is discussed. The application of powder metallurgy to the production of turbine disks is considered. It is shown that oxide-dispersion strengthened alloys (including NiCr and NiCr-Al) and ceramics are the best refractory turbine vane materials. The use of heat resistant sheet alloys as combustor materials is examined. The cost benefits to be derived from the application of high temperature technology to advanced CTOL and STOL engines are described.

Blankenship, C. P.

1975-01-01

225

The relation between atmospheric humidity and temperature trends for stratospheric water  

NASA Astrophysics Data System (ADS)

We analyze the relation between atmospheric temperature and water vapor—a fundamental component of the global climate system—for stratospheric water vapor (SWV). We compare measurements of SWV (and methane where available) over the period 1980-2011 from NOAA balloon-borne frostpoint hygrometer (NOAA-FPH), SAGE II, Halogen Occultation Experiment (HALOE), Microwave Limb Sounder (MLS)/Aura, and Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) to model predictions based on troposphere-to-stratosphere transport from ERA-Interim, and temperatures from ERA-Interim, Modern Era Retrospective-Analysis (MERRA), Climate Forecast System Reanalysis (CFSR), Radiosonde Atmospheric Temperature Products for Assessing Climate (RATPAC), HadAT2, and RICHv1.5. All model predictions are dry biased. The interannual anomalies of the model predictions show periods of fairly regular oscillations, alternating with more quiescent periods and a few large-amplitude oscillations. They all agree well (correlation coefficients 0.9 and larger) with observations for higher-frequency variations (periods up to 2-3 years). Differences between SWV observations, and temperature data, respectively, render analysis of the model minus observation residual difficult. However, we find fairly well-defined periods of drifts in the residuals. For the 1980s, model predictions differ most, and only the calculation with ERA-Interim temperatures is roughly within observational uncertainties. All model predictions show a drying relative to HALOE in the 1990s, followed by a moistening in the early 2000s. Drifts to NOAA-FPH are similar (but stronger), whereas no drift is present against SAGE II. As a result, the model calculations have a less pronounced drop in SWV in 2000 than HALOE. From the mid-2000s onward, models and observations agree reasonably, and some differences can be traced to problems in the temperature data. These results indicate that both SWV and temperature data may still suffer from artifacts that need to be resolved in order to answer the question whether the large-scale flow and temperature field is sufficient to explain water entering the stratosphere.

Fueglistaler, S.; Liu, Y. S.; Flannaghan, T. J.; Haynes, P. H.; Dee, D. P.; Read, W. J.; Remsberg, E. E.; Thomason, L. W.; Hurst, D. F.; Lanzante, J. R.; Bernath, P. F.

2013-01-01

226

Temperature and precipitation trends on the southern slopes of Mt Everest during the last twenty years (1994-2013)  

NASA Astrophysics Data System (ADS)

The current uncertainties on Himalayan glacier shrinkage is mainly attributed to lack of meteorological measurements. The need for a fine scale investigation is particularly evident in the south slope of Mt Everest as it is one of the heavily glaciated parts of the Himalaya. To fill this knowledge gap the ''Pyramid'' station (5050 m) was created by Ev-K2-CNR Committee since the 1990. This meteorological observatory is located at the highest elevation at which weather data have ever been gathered in the region and thus the collected time series represents a valuable dataset to investigate the climate change in southern central Himalaya. However the remoteness and the harsh conditions of the region has determined over the years complications of operating of the automated weather stations (AWS) which do not have allowed to make long-term measurement coming from a unique station. In this context, we propose here a monthly temperature and precipitation reconstruction of the last twenty years (1994-2013) (and associated uncertainty) using quantile mapping and expectation maximization techniques using all the available in situ measurements. We observed an increase of +0.53±0.12°C which is comparable to that of the Northern Hemisphere. However, the trend is significant at 90%. In addition, the increasing trend is concentrated in the winter months. The implications of these findings are significant. The melting of glaciers is ascribed to the temperature increase during the summer, while we observe a stationary trend during the warmer months. Consequently, the role of precipitation and solar radiation becomes central in the climate change impact studies of the region. As regards to the precipitation trend, we observe a substantial decrease (about -16.2 ±1.1 mm y-1 of precipitation, p<0.001) both for winter and summer months. Our results agree with the findings from other research groups that refer to a weakening of the monsoon from the '70s. These results are compared to the time series of other 25 AWSs located at lower elevations (Nepali Department of Hydrology and Meteorology -DHM-) and one located on the north slope of Mt Everest (Chinese Academy of Science -CAS-). Afterwards, we evaluate the agreement of these meteorological land stations with reanalysis and gridded data in order to investigate the possible spatial extension of our observations. In general, this study has as its ultimate goal to use all our available figures in order to expand and streamline the current knowledge on climate drivers in southern central Himalaya and allow thus interpreting the observed impacts on cryoshere of the region.

Salerno, Franco; Ma, Yaoming; Guyennon, Nicolas; Thakuri, Sudeep; Viviano, Gaetano; Romano, Emanuele; Vuillermoz, Elisa; Stocchi, Paolo; Tartari, Gianni

2014-05-01

227

Analysis of interdecadal trends in chlorophyll and temperature in the Central Basin of Long Island Sound  

NASA Astrophysics Data System (ADS)

Few coastal systems have time series data that allow researchers to examine the impact of two important stressors on estuarine ecosystems: climate change and eutrophication. The Central Basin of Long Island Sound (LIS), between New York and Connecticut, is one such system. LIS has seen annual average surface temperatures increase at a rate of 0.03 °C/yr since 1976, with increases most pronounced during summer and early fall. Over the past 15 years, annual stratification (difference between mean annual surface and bottom temperatures) has also increased at the same rate. Despite expansion of waste-water treatment and declining point-source nutrient input, LIS remains eutrophic. An increase toward historic mean annual chlorophyll concentration has occurred since a minimum in the early 1990s, driven in part by higher fall chlorophyll values. There is also an apparent shift in the seasonality of phytoplankton blooms, with more frequent fall chlorophyll peaks and reduced early spring peaks relative to the 1950s. Non-metric Multidimensional Scaling (NMDS) analysis of phytoplankton communities from fall and summer 2002-8 indicated that cyanobacteria and flagellates are associated with higher amounts of chlorophyll at higher temperatures during these two seasons. These results suggest that as surface temperatures continue to increase, smaller cells and flagellates may maintain chlorophyll values at higher levels despite decreased or static surface nutrient concentrations in this system.

Rice, Edward; Stewart, Gillian

2013-08-01

228

Temperature trends in the tropical upper troposphere and lower stratosphere: connections  

E-print Network

surface temperatures and implications for water vapor and ozone C. I. Garfinkel 1,2 , D. W. Waugh 1 , L. D. Oman 3 , L. Wang 1 , M. M. Hurwitz 3,4 Chaim I. Garfinkel, Department of Earth and Planetary Science and Planetary Science, Johns Hopkins University, Baltimore, MD 21218. Luke D. Oman, NASA Goddard Space Flight

Waugh, Darryn W.

229

The relation between atmospheric humidity and temperature trends for stratospheric water  

NASA Astrophysics Data System (ADS)

We analyse the relation between atmospheric temperature and water vapour - a fundamental component of the global climate system - for stratospheric water vapour (SWV). We compare measurements of SWV (and methane where available) over the period 1980-2011 from the NOAA Frostpoint Hygrometer (NOAA-FPH), Stratospheric Aerosol and Gas Experiment II (SAGE-II), Halogen Occultation Experiment (HALOE), and Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) to model predictions based on troposphere-to-stratosphere transport from the ERA-Interim reanalysis, and temperatures from three reanalyses (ERA-Interim, MERRA, and CFSR), and three homogenised radiosonde datasets (RATPAC, HadAT2 and RICHv1.5). All model predictions are dry biased. The interannual anomalies of the model predictions show periods of fairly regular oscillations, alternating with more quiescent periods and a few large-amplitude oscillations. They all agree well (correlation coefficients 0.9 and larger) with observations for higher-frequency variations (periods up to 2-3 years). Differences between SWV observations, and temperature data, respectively, render analysis of the model-observation residual difficult. However, we find fairly well-defined periods of drifts in the residuals. For the 1980's model predictions differ most, and only the calculation with ERA-Interim temperatures is roughly within observational uncertainties. All model predictions show a drying relative to HALOE in the 1990's, followed by a moistening in the early 2000's. Drifts to NOAA-FPH are similar (but stronger), whereas no drift is present against SAGE-II. As a result, the model calculations have a less pronounced drop in SWV in 2000 than HALOE. From the mid-2000's onwards, models and observations agree reasonably, and some differences can be traced to problems in the temperature data. These results indicate that both SWV and temperature data may still suffer from artefacts that need to be resolved in order to answer the question whether the large-scale flow and temperature field is sufficient to explain water entering the stratosphere.

Fueglistaler, S.; Liu, Y.; Flannaghan, T.; Haynes, P.; Dee, D.; Remsberg, E. E.; Thomason, L.; Hurst, D. F.; Lanzante, J.; Bernath, P. F.; Read, W.

2012-12-01

230

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

231

Evaluation of trends in some temperature series at some Italian stations and their modelling by means of spectral methods: first results in the Latium coastal area  

NASA Astrophysics Data System (ADS)

The investigation of the presence of signals indicating possible climatic changes in progress during the second half of the last century in the coastal area of the central Tyrrhenian sea has been carried out within the context of a research programme promoted by the Italian Science Academy (alias "the Academy of the XL") and financed by the Presidential Bureau. Our goal has been a better understanding of the behaviour of the minimum and maximum temperature variations in the period 1951-1999 and the modelling of their stochastic residuals through spectral analysis and the optimized construction of suitable autoregressive one-parameter processes. The meteorological data source for this research was the Italian "Agrometeorological National DataBase" (BDAN) of the Agrometeorological Informatics National System (SIAN). The spectral and stochastic analysis of meteorological data usually require full data sets without gaps, but, in BDAN, numerous data sets taken at stations located in the investigated area were incomplete. Thus, after the selection of an adequate number of stations, both representative of the region under study and characterized by a low number of data gaps, the first step was to fill all the gaps in the daily series using specific statistical techniques. After this preliminary treatment, we were left with seven temperature series that showed enough good characteristics in order to carry out an efficient modelling. Spectral analysis of minimum and maximum temperature series permitted to identify an auto-regressive one-parameter model well representing the stochastic residual of each series. With the aid of the complete model, consisting of a deterministic component (a linear trend plus two seasonal oscillations) and a stochastic residual, one can satisfactorily reconstruct the data in the past (climatic historical analysis) and to try a prediction of future values (forecasting). Thus the proposed model appears to represent a valid method to evaluate the whole variability of each climatic series in a multi-decadal time scale. As for the deterministic component, the Fourier analysis of minimum and maximum temperatures series showed for each station the existence, beside the secular linear trend, of a first oscillation (annual), and a secondary oscillation (half-yearly), each characterized by an amplitude and a phase. On the other hand, the stochastic residual can always be regarded as the superposition of an AR(1) process and a residual white noise. The lower half-yearly seasonal component, although small, can produce an amplitude attenuation or enhancement, and a phase advance or delay, among the climatic expected values and the standard meteorological sequences. The results of the stochastic analysis showed the presence during the period 1951-1999 of a discrete variability in the minimum and maximum temperature series along the Tyrrhenian coastal area, more intense for minimum temperatures. This behaviour can have direct and indirect consequences on natural vegetation and on the planning of agricultural activity, in particular for what concerns the evaluation of the quantity of the "available energy" for plant development and the assessment of "production sustainability" for the agricultural crops in terms of quantity, cost and quality of the agro products.

Beltrano, M. C.; Testa, O.; Malvestuto, V.; Esposito, S.

2010-09-01

232

Mesopause Temperature Retrieval from SATI Measured Spectra with a Linear Background Component. Results from the Numerical Simulation  

E-print Network

The Spectral Airglow Temperature Imager is a ground-based spectral instrument for spatial registration of airglow emissions. The basic aim of the instrument development is the investigation of gravity waves based on the spatial characteristics of the temperature field at the altitude of mesopause and its evolution in the time. The temperature retrieval is based on matching measured and preliminary calculated synthetic spectra. Possibilities are presented for generalization of the basic regression equation which connects the measured and the synthetic spectra. A linear change of the background for the entire filter transmittance interval was presumed. Numerical experiments by Monte-Karlo simulation were conducted. The presented results show a bigger stability of the proposed approach in comparison with the traditional one, without considering the linear background.

Atanassov, Atanas Marinov

2012-01-01

233

Climate change in the Colorado Rocky Mountains: free air versus surface temperature trends  

Microsoft Academic Search

A high elevation data set of surface temperatures from the Front Range of the Rocky Mountains in Colorado, USA, is analysed for evidence of long-term change (1952-98). Sites range from the high plains of Colorado (1509 m) to the alpine tundra (3749 m). Systematic changes in surface-based lapse rates are uncovered, with absolute cooling at the highest elevations, but little

N. Pepin; M. Losleben

2002-01-01

234

A century of climate and ecosystem change in Western Montana: what do temperature trends portend?  

Microsoft Academic Search

The physical science linking human-induced increases in greenhouse gasses to the warming of the global climate system is well\\u000a established, but the implications of this warming for ecosystem processes and services at regional scales is still poorly\\u000a understood. Thus, the objectives of this work were to: (1) describe rates of change in temperature averages and extremes for\\u000a western Montana, a

Gregory T. Pederson; Lisa J. Graumlich; Daniel B. Fagre; Todd Kipfer; Clint C. Muhlfeld

2010-01-01

235

Spatial and temporal trends of mean and extreme rainfall and temperature for the 33 urban centers of the arid and semi-arid state of Rajasthan, India  

NASA Astrophysics Data System (ADS)

Trend analysis of the mean (monsoon season, non-monsoon season and annual) and extreme annual daily rainfall and temperature at the spatial and temporal scales was carried out for all the 33 urban centers of the arid and semi-arid state of Rajasthan, India. Statistical trend analysis techniques, namely the Mann-Kendall test and Sen's slope estimator, were used to examine trends (1971-2005) at the 10% level of significance. Both positive and negative trends were observed in mean and extreme events of rainfall and temperature in the urban centers of Rajasthan State. The magnitude of the significant trend of monsoon rainfall varied from (-) 6.00 mm/hydrologic year at Nagaur to (-) 8.56 mm/hydrologic year at Tonk. However, the magnitude of the significant negative trends of non-monsoon rainfall varied from (-) 0.66 mm/hydrologic year at Dungarpur to (-) 1.27 mm/hydrologic year at Chittorgarh. The magnitude of positive trends of non-monsoon rainfall varied from 0.93 mm/hydrologic year at Churu to 1.70 mm/hydrologic year at Hanumangarh. The magnitude of the significant negative trends of annual rainfall varied from (-) 6.47 mm/year at Nagaur to (-) 10.0 mm/year at Tonk. The minimum, average and maximum temperature showed significant increasing warming trends on an annual and seasonal scale in most of the urban centers in Rajasthan State. The magnitude of statistically significant annual extreme daily rainfall varied from 2.00 mm at Jhalawar to (-) 1.64 mm at Tonk, while the magnitude of statistically significant extreme annual daily minimum and maximum temperature varied from 0.03 °C at Ganganagar to 0.05 °C at Jhalawar, respectively. The spatial variations of the trends in mean (monsoon season, non-monsoon season and annual) and extreme annual daily rainfall and temperature were also determined using the inverse-distance-weighted (IDW) interpolation technique. IDW results are helpful to identify trends and variability in mean and extreme rainfall and temperature in space and time for the study locations where the data is not available and the quality of data is not good. These spatial maps of temperature and rainfall can help local stakeholders and water managers to understand the risks and vulnerabilities related to climate change in terms of mean and extreme events in the region.

Pingale, Santosh M.; Khare, Deepak; Jat, Mahesh K.; Adamowski, Jan

2014-03-01

236

Long-term trends and regime shifts in sea surface temperature on the continental shelf of the northeast United States  

NASA Astrophysics Data System (ADS)

We investigated sea surface temperature (SST) variability over large spatial and temporal scales for the continental shelf region located off the northeast coast of the United States between Cape Hatteras, North Carolina, and the Gulf of Maine using the extended reconstruction sea surface temperature (ERSST) dataset. The ERSST dataset consists of 2°×2° (latitude and longitude) monthly mean values computed from in situ data derived from the International Comprehensive Ocean Atmosphere Data Set (ICOADS). Nineteen 2°×2° bins were chosen that cover the shelf region of interest between the years of 1854 and 2005. Mean annual and range of SST were examined using dynamic factor analysis to estimate trends in both parameters, while chronological clustering was used to determine temporal SST patterns and breakpoints in the time series that are believed to signal regime shifts in SST. Both SST and SST trend analysis show that interannual variability of SST fluctuations shows strong coherence between bins, with declining SST at the beginning of the last century, followed by increasing SST through 1950, and then rapidly decreasing between 1950 and mid-1960s, with somewhat warmer SST thereafter to present. Annual SST range decreases in a seaward direction for all bins, with strong coherence for interannual variability of range fluctuations between bins. The trend in SST range shows a decreasing range at the beginning of the last century followed by an increase in range from 1920 to the late-1980s, remaining high through present with some spatial variability. A more detailed spatial analysis was conducted by grouping the data into 7 regions using principal component analysis. We analyzed regional trends in mean annual SST, seasonal SST range (summer SST-winter SST), and normalized SST minima and maxima. Both the summer and winter seasons were also analyzed using the length of each season and amplitude of the warming and cooling season, respectively, along with the spring warming and fall cooling rates. Trends in all of the parameters were examined after low-pass filtering using a 10-point convolution filter ( n=10 years) and regime shifts were identified using the sequential t-test analysis of regime shifts (STARS) method. The analysis shows some difference between regions in the timing of minimum SST with minima being reached 1 month earlier in the south (February) relative to more northern regions (March). Regional annual SST range decreased in a seaward direction. Amplitude of summer warming and the length of summer have shown fluctuations with recent years showing stronger warming and longer summers but generally not exceeding past levels. Overall, the difference in SST range, with recent larger values may be the most significant finding of this work. SST range changes have the potential to disrupt species important to local fisheries due to combinations of differing temperature tolerances, changes in reproduction potential, and changes in the distributional range of species.

Friedland, Kevin D.; Hare, Jonathan A.

2007-11-01

237

Depletion, quantum jumps, and temperature measurements of ??Sr? ions in a linear Paul Trap  

E-print Network

This thesis describes the design and construction of two laser systems to probe the 674nm transition of ??Sr? ions in a linear Paul trap. The first laser system made use of a molecular transition in Iodine to stabilize the ...

Richerme, Philip J

2006-01-01

238

High Temperature Thermosets and Ceramics Derived from Linear Carborane-(Siloxane or Silane)-Acetylene Copolymers.  

National Technical Information Service (NTIS)

This invention relates to a new class of novel inorganic-organic hybrid thermosetting polymers and ceramics that are formed from novel linear polymers of varying molecular weight and varying carborane content. These novel organoboron thermoset polymers an...

D. Y. Son, T. M. Keller

1994-01-01

239

Temperature trends in desert cities: how vegetation and urbanization affect the urban heat island dynamics in hyper-arid climates  

NASA Astrophysics Data System (ADS)

Urban areas represent a unique micro-climatic system, mainly characterized by scarcity of vegetation and ground moisture, an albedo strictly dependent on building materials and urban forms, high heat capacity, elevated pollutants emissions, anthropogenic heat production, and a characteristic boundary layer dynamics. For obvious historical reasons, the first to be addressed in the literature were the effects of urbanization on the local microclimate of temperate regions, where most of the urban development took place in the last centuries. Here micro-climatic characteristics all contribute to the warming of urban areas, also known as 'urban heat island' effect, and are expected to crucially impact future energy and water consumption, air quality, and human health. However, rapidly increasing urbanization rates in arid and hyper-arid developing countries could soon require more attention towards studying the effects of urban development on arid climates, which remained mainly unexplored till now. In this talk we investigate the climatology of urban heat islands in seven highly urbanized desert cities based on day and night temporal trends of land surface temperature (LST) and normalized difference vegetation index (NDVI) acquired using MODIS satellite during 2000-2012. Urban and rural areas are distinguished by analyzing the high-resolution temporal variability and averaged monthly values of LST, NDVI and Surface Urban Heat Island (SUHI) for all the seven cities and adjacent sub-urban areas. Different thermal behaviors were observed at the selected sites, also including temperature mitigation and inverse urban heat island, and are here discussed together with detailed analysis of the corresponding trends.

Marpu, P. R.; Lazzarini, M.; Molini, A.; Ghedira, H.

2013-12-01

240

Extreme climatic events drive mammal irruptions: regression analysis of 100-year trends in desert rainfall and temperature  

PubMed Central

Extreme climatic events, such as flooding rains, extended decadal droughts and heat waves have been identified increasingly as important regulators of natural populations. Climate models predict that global warming will drive changes in rainfall and increase the frequency and severity of extreme events. Consequently, to anticipate how organisms will respond we need to document how changes in extremes of temperature and rainfall compare to trends in the mean values of these variables and over what spatial scales the patterns are consistent. Using the longest historical weather records available for central Australia – 100 years – and quantile regression methods, we investigate if extreme climate events have changed at similar rates to median events, if annual rainfall has increased in variability, and if the frequency of large rainfall events has increased over this period. Specifically, we compared local (individual weather stations) and regional (Simpson Desert) spatial scales, and quantified trends in median (50th quantile) and extreme weather values (5th, 10th, 90th, and 95th quantiles). We found that median and extreme annual minimum and maximum temperatures have increased at both spatial scales over the past century. Rainfall changes have been inconsistent across the Simpson Desert; individual weather stations showed increases in annual rainfall, increased frequency of large rainfall events or more prolonged droughts, depending on the location. In contrast to our prediction, we found no evidence that intra-annual rainfall had become more variable over time. Using long-term live-trapping records (22 years) of desert small mammals as a case study, we demonstrate that irruptive events are driven by extreme rainfalls (>95th quantile) and that increases in the magnitude and frequency of extreme rainfall events are likely to drive changes in the populations of these species through direct and indirect changes in predation pressure and wildfires. PMID:23170202

Greenville, Aaron C; Wardle, Glenda M; Dickman, Chris R

2012-01-01

241

A linear regression model for predicting PNW estuarine temperatures in a changing climate  

EPA Science Inventory

Pacific Northwest coastal regions, estuaries, and associated ecosystems are vulnerable to the potential effects of climate change, especially to changes in nearshore water temperature. While predictive climate models simulate future air temperatures, no such projections exist for...

242

Impacts of land use land cover on temperature trends over the continental United States: assessment using the North American Regional Reanalysis  

Microsoft Academic Search

We investigate the sensitivity of surface temperature trends to land use land cover change (LULC) over the conterminous United States (CONUS) using the observation minus reanalysis (OMR) approach. We estimated the OMR trends for the 1979-2003 period from the US Historical Climate Network (USHCN), and the NCEP-NCAR North American Regional Reanalysis (NARR). We used a new mean square differences (MSDs)-based

Souleymane Fall; Dev Niyogi; Alexander Gluhovsky; Roger A. Pielke Sr.; Eugenia Kalnay; Gilbert Rochon

2010-01-01

243

Modelled glacier response to centennial temperature and precipitation trends on the Antarctic Peninsula  

NASA Astrophysics Data System (ADS)

The northern Antarctic Peninsula is currently undergoing rapid atmospheric warming. Increased glacier-surface melt during the twentieth century has contributed to ice-shelf collapse and the widespread acceleration, thinning and recession of glaciers. Therefore, glaciers peripheral to the Antarctic Ice Sheet currently make a large contribution to eustatic sea-level rise, but future melting may be offset by increased precipitation. Here we assess glacier-climate relationships both during the past and into the future, using ice-core and geological data and glacier and climate numerical model simulations. Focusing on Glacier IJR45 on James Ross Island, northeast Antarctic Peninsula, our modelling experiments show that this representative glacier is most sensitive to temperature change, not precipitation change. We determine that its most recent expansion occurred during the late Holocene `Little Ice Age' and not during the warmer mid-Holocene, as previously proposed. Simulations using a range of future Intergovernmental Panel on Climate Change climate scenarios indicate that future increases in precipitation are unlikely to offset atmospheric-warming-induced melt of peripheral Antarctic Peninsula glaciers.

Davies, Bethan J.; Golledge, Nicholas R.; Glasser, Neil F.; Carrivick, Jonathan L.; Ligtenberg, Stefan R. M.; Barrand, Nicholas E.; van den Broeke, Michiel R.; Hambrey, Michael J.; Smellie, John L.

2014-11-01

244

Temperature trend estimates in the troposphere over Antarctica by use of analysis of the GPS radio occultation data  

NASA Astrophysics Data System (ADS)

Analyses of the Antarctic climate change during recent decades have demonstrated a positive continent-wide average near-surface temperature trend. Strong warming of the Antarctic Peninsula in contrast to slight cooling of the Antarctic continental interior in the last five decades has been emphasised [Turner et al. 2005]. Recently, it has been reported that significant warming of the Antarctic ice-sheet surface extends well beyond the Antarctic Peninsular to cover most of West Antarctica with a warming rate exceeding 0.1°C per decade over the past 50 years, and is strongest in winter and spring [Steig et al. 2009]. Assessments of atmospheric temperature trends have also found significant warming of the Antarctic winter troposphere. Analysing data from nine Antarctic radiosonde stations, it has been shown that regional midtropospheric temperatures have increased at a statistically significant rate of 0.5 to 0.7°C per decade over the past three decades - a major warming of the Antarctic winter troposphere that is larger than any previously identified regional tropospheric warming on Earth [Turner et al. 2006]. Analysis of climate change over the Polar Regions is particularly challenging due to the scarcity of observations from a small number of sparsely located weather stations. Obviously, data obtained by various satellite remote sensing techniques are invaluable in order to obtain spatially-complete distributions of near-surface and atmospheric temperature trends in high latitudes. For example, using the climate quality records of satellite Microwave Sounding Unit (MSU) observations, it has been shown that significant tropospheric warming prevails during Antarctic winters and springs, with the largest winter tropospheric warming of about 0.6°C per decade for 1979-2005 between 120°W and 180°W [Johanson and Fu 2007]. Recently, a new atmospheric observation technique, GPS radio occultation (RO), has been developed for acquiring the Earth's atmospheric characteristics. Latest research results have demonstrated the great potential of the new technique to global climate monitoring and numerical weather prediction. With the newly launched six FORMOSAT-3 LEO satellites in 2006, thousands of high-quality, globally-distributed daily vertical profiles of refractivity, temperature and moisture have been obtained [Liou et al. 2007]. It is anticipated that GPS RO technique will play an important role in meteorological studies because of the significantly increased amount of atmospheric observations and improved data processing methodology. In this study, we use GPS RO data and collocated radiosonde data from three Australian weather observation stations (Casey, Davis and Mawson) to evaluate impacts of different collocation criteria (specifically, 100, 200 and 300 km spatial buffers and 1, 2 and 3 hour temporal buffers). Spatial and temporal variations in troposhperic temperatures over Antarctica are also investigated using the GPS RO data. Detailed analysis of refractivity and temperature profiles is presented and seasonal temperature variations in the troposphere are discussed. References Johanson, C. M., and Q. Fu, 2007: Antarctic atmospheric temperature trend patterns from satellite observations. Geophys. Res. Lett. 34, L12703, doi:10.1029/2006GL029108. Liou, Y.-A., A. G. Pavelyev, S. F. Liu, A. A. Pavelyev, N. Yen, C. Y. Huang, and C. J. Fong, 2007: FORMOSAT-3 GPS radio occultation mission: preliminary results. IEEE Trans. Geosci. Remote Sensing, 45(10), doi:10.1109/TGRS.2007.903365. Steig, E. J., D. P. Schneider, S.D. Rutherford, M. M. Mann, J. C. Comiso, and D. T. Shindell, 2009: Warming of the Antarctic ice-sheet surface since the 1957 International Geophysical Year. Nature 457, 22 January 2009, doi: 10.1038/nature07669. Turner, J., S.R. Colwell, G.J. Marshall, T.A. Lachlan-Cope, A.M. Carleton, P.D. Jones, V. Lagun, P.A. Reid, and S. Iagovkina, 2005: Antarctic climate change during the last 50 years. Int. J. Climatol. 25, 279-294. Turner, J., T. A. Lachlan-Cope, S. Colwell, G. J. Marshall, and W. M. Connolley, 2006: Signif

Zhang, Kefei; Fu, Erjiang; Wang, Chuan-Sheng; Liou, Yuei-An; Pavelyev, Alexander; Kuleshov, Yuriy

2010-05-01

245

Small eigenvalues of the low temperature linear relaxation Boltzmann equation with a confining potential  

E-print Network

We study the linear relaxation Boltzmann equation, a simple semiclassical kinetic model. We provide a resolvent estimate for an associated non-selfadjoint operator as well as an estimate on the return to equilibrium. This is done using a scaling argument and non-semiclassical hypocoercive estimate.

Virgile Robbe

2014-10-31

246

On using a generalized linear model to downscale daily precipitation for the center of Portugal: an analysis of trends and extremes  

NASA Astrophysics Data System (ADS)

Portugal is on a climate change hot spot region, where precipitation is expected to decrease with important impacts regarding future water availability. As one of the European countries affected more by droughts in the last decades, it is important to assess how future precipitation regimes will change in order to study its impacts on water resources. Due to the coarse scale of global circulation models, it is often needed to downscale climate variables to the regional or local scale using statistical and/or dynamical techniques. In this study, we tested the use of a generalized linear model, as implemented in the program GLIMCLIM, to downscale precipitation for the center of Portugal where the Tagus basin is located. An analysis of the method performance is done as well as an evaluation of future precipitation trends and extremes for the twenty-first century. Additionally, we perform the first analysis of the evolution of droughts in climate change scenarios by the Standardized Precipitation Index in the study area. Results show that GLIMCLIM is able to capture the precipitation's interannual variation and seasonality correctly. However, summer precipitation is considerably overestimated. Additionally, precipitation extremes are in general well recovered, but high daily rainfall may be overestimated, and dry spell lengths are not correctly recovered by the model. Downscaled projections show a reduction in precipitation between 19 and 28 % at the end of the century. Results indicate that precipitation extremes will decrease and the magnitude of droughts can increase up to three times in relation to the 1961-1990 period which can have strong ecological, social, and economic impacts.

Pulquério, Mário; Garrett, Pedro; Santos, Filipe Duarte; Cruz, Maria João

2014-05-01

247

The natural circulation solar water heater model with linear temperature distribution  

Microsoft Academic Search

This paper presents an analysis of natural circulation of a compact thermosyphon solar domestic hot water (SDHW) system produced and commercialised locally in Algeria. Calculations and measurements were performed on the mass flow rate, temperature rise fluid and absorber temperatures inside the thermosyphon of parallel tube design. Comparison between experimental and theoretical results is presented.

A. Zerrouki; A. Boumédien; K. Bouhadef

2002-01-01

248

Perpendicular wavenumber dependence of the linear stability of global ion temperature gradient modes on E × B flows  

NASA Astrophysics Data System (ADS)

Sheared E × B flows are known to stabilize turbulence. This paper investigates how the linear stability of the ion-temperature-gradient (ITG) mode depends on k? in both circular and MHD geometry. We study the effects of both rotation profiles of constant shear and of purely toroidal flow taken from experiment, using the global gyrokinetic particle-in-cell code NEMORB. We find that in order to effectively stabilize the linear mode, the fastest growing mode requires a shearing rate (?E) around 1-2 times its linear growth rate without flow (?0), while both longer and shorter wavelength modes need much larger flow shear compared with their static linear growth rates. Modes with k??i < 0.2 need ?E as much as 10 times their ?0. This variation exists in both large-aspect ratio circular cross-section and small-aspect ratio MHD geometries, with both analytic constant shear and experimental flow profiles. There is an asymmetry in the suppression with respect to the sign of ?E, due to competition between equilibrium profile variation and flow shear. The maximum growth rate for cases using the experimental profile in MAST equilibria occurs at shearing rates of 10% the experimental level.

Hill, P.; Saarelma, S.; McMillan, B.; Peeters, A.; Verwichte, E.

2012-06-01

249

Atmospheric temperature retrievals from lidar measurements using techniques of non-linear mathematical inversion  

NASA Astrophysics Data System (ADS)

The conventional method of retrieving atmospheric temperatures from absolute (or relative) lidar density measurements requires the assumption of a seed pressure to initiate the temperature retrieval (e.g. Hauchecorne and Chanin, 1980). An uncertainty in this choice typically results in a systematic uncertainty in retrieved temperatures near the top 10 to 15 km of the range. This uncertainty makes the retrieved temperatures at the top of the profile of insufficient quality for scientific studies of the upper atmosphere. The application of mathematical inversion was investigated as a tool to possibly remedy this problem. A grid search technique was used to develop an alternative way of retrieving atmospheric temperature profiles from Rayleigh-scatter lidar measurements. The advantage of this technique is that the seed pressure can be chosen at the bottom, rather than at the top of the measurement range. This change is expected to be an improvement because variations in pressures at the lowest heights (typically the stratosphere) are much smaller as compared to those in the upper mesosphere or lower thermosphere, resulting in smaller uncertainties in the retrieved profile, particularly at the top of the atmosphere. Hence, use of this technique is equivalent to increasing the lidar's power-aperture product by about 4 times. After successful testing of the method on simulated lidar measurements, measurements obtained by The University of Western Ontario's Purple Crow lidar were analyzed using this technique. Results will be shown which conclusively demonstrate that this technique allows the lidar to retrieve temperatures up to heights where sufficient photocounts are obtained without large uncertainties due to seed pressure. One of the major challenges in this work was devising a numerical scheme to estimate the uncertainties in retrieved temperatures. A Monte Carlo method was used to estimate standard errors in the retrieved temperatures. The statistical uncertainties retrieved using this scheme are consistent with the statistical uncertainties in the conventional technique. In addition the systematic errors due to uncertainties in seed pressure and other input parameters can be retrieved separately from the statistical uncertainties. A. Hauchecorne and M. L. Chanin, Density and temperature profiles obtained by lidar between 35 and 70 km. Geophys. Res. Lett., 1980.

Khanna, J.; Sica, R. J.; McElroy, C. T.

2011-12-01

250

Hourly predictive Levenberg-Marquardt ANN and multi linear regression models for predicting of dew point temperature  

NASA Astrophysics Data System (ADS)

In this study, the ability of two models of multi linear regression (MLR) and Levenberg-Marquardt (LM) feed-forward neural network was examined to estimate the hourly dew point temperature. Dew point temperature is the temperature at which water vapor in the air condenses into liquid. This temperature can be useful in estimating meteorological variables such as fog, rain, snow, dew, and evapotranspiration and in investigating agronomical issues as stomatal closure in plants. The availability of hourly records of climatic data (air temperature, relative humidity and pressure) which could be used to predict dew point temperature initiated the practice of modeling. Additionally, the wind vector (wind speed magnitude and direction) and conceptual input of weather condition were employed as other input variables. The three quantitative standard statistical performance evaluation measures, i.e. the root mean squared error, mean absolute error, and absolute logarithmic Nash-Sutcliffe efficiency coefficient ( {| {{{Log}}({{NS}})} |} ) were employed to evaluate the performances of the developed models. The results showed that applying wind vector and weather condition as input vectors along with meteorological variables could slightly increase the ANN and MLR predictive accuracy. The results also revealed that LM-NN was superior to MLR model and the best performance was obtained by considering all potential input variables in terms of different evaluation criteria.

Zounemat-Kermani, Mohammad

2012-08-01

251

Reconciling spatial and seasonal variations in Northern Hemisphere surface air temperature trends with a pointwise dynamical adjustment  

NASA Astrophysics Data System (ADS)

On a regional scale, dynamical processes associated with storms and teleconnections account for much of the month-to-month and year-to-year variability of surface air temperature (SAT), especially over the middle and high latitude Northern Hemisphere continents during the boreal cold season. It is only when temperatures are globally averaged and smoothed in time that the signature of human-induced global warming becomes clearly evident. An effective way to render the regional and global warming signatures more prominent is to adjust the monthly SAT field to remove this dynamically-induced variability. In previous studies, such "dynamical adjustments" have been applied to time series of hemispheric or global-mean SAT. Here a pointwise dynamical adjustment is performed on the monthly-mean cold season (November-April) SAT field based on sea-level pressure (SLP) patterns in the domain poleward of 20°N. Grid point SAT time series are adjusted independently based on a set of mutually orthogonal time series defined as the expansion coefficients of the first two SLP predictor patterns derived from partial least squares (PLS) regression. Results indicate that the pointwise dynamical adjustment accounts for about half the variance of the SAT field over the entire Northern Hemisphere and up to 70% of the variance over the mid- and high-latitude continental interiors. Over the continents poleward of 40°N the dynamical contribution accounts for almost half the November-April warming trend from 1965 to 2000. Applying a dynamical adjustment enhances the spatial and seasonal coherence of the global warming signal. The pointwise approach improves on previous adjustments based on area-mean SAT by producing an adjusted SAT field that may be further analyzed for features that might otherwise be obscured by dynamically-induced variability, such as polar amplification or seasonal differences associated with radiative processes.

Smoliak, B. V.; Lin, P.; Fu, Q.; Wallace, J. M.

2012-12-01

252

A Microfluidic Device with a Linear Temperature Gradient for Parallel and Combinatorial Measurements  

E-print Network

channels simultaneously. This result is exploited to rapidly obtain activation energies from catalytic as well as the determination of phase transition temperatures and activation energies from single) Fodor, S. P. A.; Read, J. L.; Pirrung, M. C.; Stryer, L.; Lu, A. T.; Solas, D. Science 1991, 251, 767

253

Pacific Sea Surface Temperatures in the Twentieth Century: An Evolution-Centric Analysis of Variability and Trend  

Microsoft Academic Search

A consistent analysis of natural variability and secular trend in Pacific SSTs in the 20th century is presented. By focusing on spatial and temporal recurrence, but without imposition of periodicity constraints, this single analysis discriminates between biennial, ENSO and decadal variabilities, leading to refined evolutionary descriptions; and between these natural variability modes and secular trend; all without advance filtering (and

B. Guan; S. Nigam

2007-01-01

254

The impact of the Madden-Julian Oscillation trend on the Arctic amplification of surface air temperature during the 19792008  

E-print Network

The impact of the Madden-Julian Oscillation trend on the Arctic amplification of surface air period, MJO phases 4­6 exhibited a large increase and phases 1­2 a mod- erate decrease in their frequency with the poleward propagation mechanism of Lee et al. (2011a, 2011b). By incorporating both the trend in MJO phase

Lee, Sukyoung

255

Design of High Temperature Ultrasonic Linear Arrays for Under-Sodium Viewing  

SciTech Connect

This paper summarizes the design process for high temperature ultrasonic phased array transducers for imaging in liquid sodium at temperatures up to 260C. The project is funded by the USDOE Generation IV Reactor Program and includes collaboration with the Japanese Atomic Energy Agency. The transducer system is being designed to be able to provide images inside a sodium cooled fast reactor, to support operation and maintenance activities including potentially location of looseor damaged parts during service outages. The prototype transducer array is being designed for 8 to 16, 3MHz rectangular lead niobate (K-81) or bismuth titanate (K-15) piezoelectric elements spaced at ?/2 (wavelength in sodium). A nickel or nickel alloy faceplate serves as the sodium wetting surface. Scan angle of the focused ultrasonic beam is ±30 degrees. Imaging spatial resolution is ? 1mm. The array is designed to be operated using a commercial phased array control system and it is planned that array testing will be performed in room temperature water, hot oil (260C), and molten sodium (260C).

Griffin, Jeffrey W.; Bond, Leonard J.; Jones, Anthony M.; Peters, Timothy J.

2010-11-07

256

Long-memory effects in linear-response models of Earth's temperature and implications for future global warming  

E-print Network

A linearized energy-balance model for global temperature is formulated, featuring a scale-free long-range memory (LRM) response and stochastic forcing representing the influence on the ocean heat reservoir from atmospheric weather systems. The model is parametrized by an effective response strength, the stochastic forcing strength, and the memory exponent. The instrumental global surface temperature record and the deterministic component of the forcing are used to estimate these parameters by means of the maximum-likelihood method. The residual obtained by subtracting the deterministic solution from the observed record is analyzed as a noise process and shown to be consistent with a long-memory time-series model and inconsistent with a short-memory model. By decomposing the forcing record in contributions from solar, volcanic, and anthropogenic activity one can estimate the contribution of each to 20'th century global warming. The LRM model is applied with a reconstruction of the forcing for the last millenni...

Rypdal, Martin

2013-01-01

257

Direct evidence for continuous linear kinetics in the low-temperature degradation of Y-TZP.  

PubMed

The kinetics of the tetragonal to monoclinic (t-m) transformation of zirconia in a hydrous environment at 134°C and 3 bar pressure was studied. As surface X-ray diffraction, which is conventionally used to explore the progress, has a very limited depth of information, it distorts the quantitative results in a layer-on-layer situation and by itself is ill suited for this reason. Analyzing cross sections is more suitable; therefore, focused ion beam techniques were used to prepare artifact-free cuts. The material was subsequently investigated by scanning electron microscopy, electron backscatter diffraction and Raman spectroscopy. Only the combination of methods makes it possible to resolve the quantifiable details of the process. The transformation starts in the near-surface areas, forms a layer, and the growth of this layer proceeds into the bulk material following a simple linear time law (0.0624 ?m h(-1) for material in the chosen condition), without apparent retardation or limit. The progress yields a gradientless layer with a fixed amount of residual tetragonal zirconia (~27% for 3Y-TZP in the present conditions) separated from unaffected material by a boundary, which has a roughness only in the grain size range. The kinetics indicates a reaction rate control, where the hydration reaction is the key factor, but is modified by the stepwise access of water to the reaction front opened by the autocatalytic transformation of zirconia with a critical hydration level. PMID:22925608

Keuper, M; Eder, K; Berthold, C; Nickel, K G

2013-01-01

258

An Analysis of Simulated and Observed Global Mean Near-Surface Air Temperature Anomalies from 1979 to 1999: Trends and Attribution of Causes  

NASA Technical Reports Server (NTRS)

The 1979 - 1999 response of the climate system to variations in solar spectral irradiance is estimated by comparing the global averaged surface temperature anomalies simulated by a 2D (two dimensional) energy balance climate model to observed temperature anomalies. We perform a multiple regression of southern oscillation index and the individual model responses to solar irradiance variations, stratospheric and tropospheric aerosol loading, stratospheric ozone trends, and greenhouse gases onto each of five near-surface temperature anomaly data sets. We estimate the observed difference in global mean near surface air temperature attributable to the solar irradiance difference between solar maximum and solar minimum to be between 0.06 and 0.11 K, and that 1.1 - 3.8% of the total variance in monthly mean near-surface air temperature data is attributable to nations in solar spectral irradiance. For the five temperature data sets used in our analysis, the trends in raw monthly mean temperature anomaly data have a large range, spanning a factor of 3 from 0.06 to 0.17 K/decade. However. our analysis suggests that trends in monthly temperature anomalies attributable to the combination of greenhouse gas, stratospheric ozone, and tropospheric sulfate aerosol variations are much more consistent among data sets, ranging from 0.16 to 0.24 K/decade. Our model results suggest that roughly half of the warming from greenhouse gases is cancelled by the cooling from changes in stratospheric ozone. Tropospheric sulfate aerosol loading in the present day atmospheric contributes significantly to the net radiative forcing of the present day climate system. However, because the change in magnitude and latitudinal distribution of tropospheric sulfate aerosol has been small over the past 20 years, the change in the direct radiative forcing attributable to changes in aerosol loading over this time is also small.

MacKay, R. M.; Ko, M. K. W.

2001-01-01

259

Differences between two climatological periods (2001-2010 vs. 1971-2000) and trend analysis of temperature and precipitation in Central Brazil  

NASA Astrophysics Data System (ADS)

In the framework of the IWAS/Água-DF project, this study focuses on changes in mean surface air temperature and accumulated precipitation in Central Brazil over the past 40 years. It has two main objectives: (1) comparison between two climatological periods (2001-2010 and 1971-2000) and (2) trend analysis of climate variables. Time series of meteorological and rain gauge stations from Central Brazil have been organized in a databank, which contains tools for homogeneity tests. From that, 4 temperature and 55 precipitation time series were sufficient homogeneous, while 1 temperature and 5 precipitation time series were identified as inhomogeneous. Reliable spatial distribution was produced using proper interpolation method. Trends and significance levels were calculated by Rapp's estimator of slope and Mann-Kendall test, respectively. The most important results of the comparisons and trend analysis in the last four decades are: (1) marked increase in annual and seasonal mean surface air temperature, (2) evident decreases of accumulated rainfall in winter and autumn, and (3) apparent increase of precipitation amounts in the rainy season.

Borges, Pablo de Amorim; Franke, Johannes; do Santos Silva, Fabrício Daniel; Weiss, Holger; Bernhofer, Christian

2014-04-01

260

Theory of coupled whistler-electron temperature gradient mode in high beta plasma: Application to linear plasma device  

SciTech Connect

This paper presents a theory of coupled whistler (W) and electron temperature gradient (ETG) mode using two-fluid model in high beta plasma. Non-adiabatic ion response, parallel magnetic field perturbation ({delta}B{sub z}), perpendicular magnetic flutter ({delta}B{sub perpendicular}), and electron collisions are included in the treatment of theory. A linear dispersion relation for whistler-electron temperature gradient (W-ETG) mode is derived. The numerical results obtained from this relation are compared with the experimental results observed in large volume plasma device (LVPD) [Awasthi et al., Phys. Plasma 17, 42109 (2010)]. The theory predicts that the instability grows only where the temperature gradient is finite and the density gradient flat. For the parameters of the experiment, theoretically estimated frequency and wave number of W-ETG mode match with the values corresponding to the peak in the power spectrum observed in LVPD. By using simple mixing length argument, estimated level of fluctuations of W-ETG mode is in the range of fluctuation level observed in LVPD.

Singh, S. K.; Awasthi, L. M.; Singh, R.; Kaw, P. K.; Jha, R.; Mattoo, S. K. [Institute for Plasma Research, Bhat, Gandhinagar 382 428 (India)

2011-10-15

261

Two Americas: Racial Differences in Child Poverty in the U.S. A Linear Trend Analysis to the Year 2010. Research in Progress Working Paper.  

ERIC Educational Resources Information Center

This analysis is the third in the Center's series on child poverty in America. The first part of this study is a historical view of trends in child poverty by race and Hispanic origin for children in families below the age of 18 years. The second part presents projections of child poverty rates and levels for the three largest racial groups to the…

Cook, John T.; Brown, J. Larry

262

Long-term trends observed in the middle atmosphere temperatures using ground based LIDARs and satellite borne measurements  

NASA Astrophysics Data System (ADS)

Long-term data available from Lidar systems located at three different locations namely São José dos Campos, Brazil (23.2° S, 45.8° W), Gadanki (13.5° N, 79.2° E) and Reunion (20.8° S, 55.5° E) have been used to investigate the long-term variations like Annual, Semi-annual, Quasi-biennial, El Nino Southern Oscillation and solar cycle. These oscillations are also extracted from simultaneous satellite borne measurements of HALogen Occultation Experiment (HALOE) instrument onboard UARS and SABER onboard TIMED over these stations making largest time series covering the entire middle atmosphere. A good agreement is found between the LIDAR and satellite-derived amplitudes and phases between 30 and 65 km altitude, which suggests that satellite measurements can be used to investigate the long-term trends globally. Latter measurements are extended to 80 km in order to further investigate these oscillations. Large difference in the amplitudes between the eastern pacific and western pacific is noticed in these oscillations. Changing from cooling trends in the stratosphere to warming trends in the mesosphere occurs more or less at altitude around 70 km altitude and this result agrees well with that observed by satellite measurements reported in the literature. The peak in the cooling trend does not occur at a fixed altitude in the stratosphere however maximum warming trend is observed around 75 km at all the stations. The observed long-term trends including various oscillations are compared with that reported with various techniques.

Kishore, P.; Venkat Ratnam, M.; Velicogna, I.; Sivakumar, V.; Bencherif, H.; Clemesha, B. R.; Simonich, D. M.; Batista, P. P.; Beig, G.

2014-03-01

263

Optical fiber temperature sensor using a gain-switched Fabry-Perot semiconductor laser self-seeded from a linearly chirped fiber Bragg grating  

NASA Astrophysics Data System (ADS)

We present a highly sensitive fiber temperature sensor based on a gain-switched Fabry-Perot semiconductor laser self-seeded from a linearly chirped fiber Bragg grating. A temperature resolution of better than 0.1 °C was demonstrated. This sensor not only has the advantage of robustness against fluctuating light levels, but also obviates the need for fine wavelength discrimination.

Li, Shenping; Chan, K. T.

1998-12-01

264

COSMIC MICROWAVE BACKGROUND POLARIZATION AND TEMPERATURE POWER SPECTRA ESTIMATION USING LINEAR COMBINATION OF WMAP 5 YEAR MAPS  

SciTech Connect

We estimate cosmic microwave background (CMB) polarization and temperature power spectra using Wilkinson Microwave Anisotropy Probe (WMAP) 5 year foreground contaminated maps. The power spectrum is estimated by using a model-independent method, which does not utilize directly the diffuse foreground templates nor the detector noise model. The method essentially consists of two steps: (1) removal of diffuse foregrounds contamination by making linear combination of individual maps in harmonic space and (2) cross-correlation of foreground cleaned maps to minimize detector noise bias. For the temperature power spectrum we also estimate and subtract residual unresolved point source contamination in the cross-power spectrum using the point source model provided by the WMAP science team. Our TT, TE, and EE power spectra are in good agreement with the published results of the WMAP science team. We perform detailed numerical simulations to test for bias in our procedure. We find that the bias is small in almost all cases. A negative bias at low l in TT power spectrum has been pointed out in an earlier publication. We find that the bias-corrected quadrupole power (l(l + 1)C{sub l} /2{pi}) is 532 {mu}K{sup 2}, approximately 2.5 times the estimate (213.4 {mu}K{sup 2}) made by the WMAP team.

Samal, Pramoda Kumar; Jain, Pankaj [Department of Physics, Indian Institute of Technology, Kanpur (India); Saha, Rajib [Jet Propulsion Laboratory, M/S 169-327, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Delabrouille, Jacques [CNRS, Laboratoire APC, 10, rue Alice Domon et Leonie Duquet, 75205 Paris (France); Prunet, Simon [Institut d'Astrophysique de Paris, 98 bis Boulevard Arago, F-75014 Paris (France); Souradeep, Tarun [Inter-University Centre for Astronomy and Astrophysics, Post Bag 4, Ganeshkhind, Pune 411007 (India)

2010-05-01

265

Long-Memory Effects in Linear Response Models of Earth's Temperature and Implications for Future Global Warming  

NASA Astrophysics Data System (ADS)

A linearized energy-balance model for global temperature is formulated, featuring a scale-free long-range memory (LRM) response and stochastic forcing representing the influence on the ocean heat reservoir from atmospheric weather systems. The model is parametrized by an effective response strength, the stochastic forcing strength, and the memory exponent. The instrumental global surface temperature record and the deterministic component of the forcing are used to estimate these parameters by means of the maximum-likelihood method. The residual obtained by subtracting the deterministic solution from the observed record is analyzed as a noise process and shown to be consistent with a long-memory time-series model and inconsistent with a short-memory model. By decomposing the forcing record in contributions from solar, volcanic, and anthropogenic activity one can estimate the contribution of each to 20'th century global warming. The LRM model is applied with a reconstruction of the forcing for the last millennium to predict the large-scale features of northern hemisphere temperature reconstructions, and the analysis of the residual also clearly favors the LRM model on millennium time scale. The decomposition of the forcing shows that volcanic aerosols give a considerably greater contribution to the cooling during the Little Ice Age than the reduction in solar irradiance associated with the Maunder minimum in solar activity. The LRM model implies a transient climate response in agreement with IPCC AR4 projections, but the stronger response on longer time scales suggests to replace the notion of equilibrium climate sensitivity by a time-scale dependent sensitivity.

Rypdal, Martin; Rypdal, Kristoffer

2014-07-01

266

Global trends  

NASA Technical Reports Server (NTRS)

Measuring trends in ozone, and most other geophysical variables, requires that a small systematic change with time be determined from signals that have large periodic and aperiodic variations. Their time scales range from the day-to-day changes due to atmospheric motions through seasonal and annual variations to 11 year cycles resulting from changes in the sun UV output. Because of the magnitude of all of these variations is not well known and highly variable, it is necessary to measure over more than one period of the variations to remove their effects. This means that at least 2 or more times the 11 year sunspot cycle. Thus, the first requirement is for a long term data record. The second related requirement is that the record be consistent. A third requirement is for reasonable global sampling, to ensure that the effects are representative of the entire Earth. The various observational methods relevant to trend detection are reviewed to characterize their quality and time and space coverage. Available data are then examined for long term trends or recent changes in ozone total content and vertical distribution, as well as related parameters such as stratospheric temperature, source gases and aerosols.

Megie, G.; Chanin, M.-L.; Ehhalt, D.; Fraser, P.; Frederick, J. F.; Gille, J. C.; Mccormick, M. P.; Schoebert, M.; Bishop, L.; Bojkov, R. D.

1990-01-01

267

A TREND BETWEEN COLD DEBRIS DISK TEMPERATURE AND STELLAR TYPE: IMPLICATIONS FOR THE FORMATION AND EVOLUTION OF WIDE-ORBIT PLANETS  

SciTech Connect

Cold debris disks trace the limits of planet formation or migration in the outer regions of planetary systems, and thus have the potential to answer many of the outstanding questions in wide-orbit planet formation and evolution. We characterized the infrared excess spectral energy distributions of 174 cold debris disks around 546 main-sequence stars observed by both the Spitzer Infrared Spectrograph and the Multiband Imaging Photometer for Spitzer. We found a trend between the temperature of the inner edges of cold debris disks and the stellar type of the stars they orbit. This argues against the importance of strictly temperature-dependent processes (e.g., non-water ice lines) in setting the dimensions of cold debris disks. Also, we found no evidence that delayed stirring causes the trend. The trend may result from outward planet migration that traces the extent of the primordial protoplanetary disk, or it may result from planet formation that halts at an orbital radius limited by the efficiency of core accretion.

Ballering, Nicholas P.; Rieke, George H.; Su, Kate Y. L. [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Montiel, Edward, E-mail: ballerin@email.arizona.edu [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803, USA. (United States)

2013-09-20

268

Molecular simulation of adsorption and separation of mixtures of short linear alkanes in pillared layered materials at ambient temperature.  

PubMed

Grand canonical Monte Carlo and configurational-bias Monte Carlo techniques are carried out to simulate the adsorption of ternary and quaternary mixtures of short linear alkanes, involving methane, ethane, propane, and n-butane, in pillared layered materials at ambient temperature, T=300 K. In the simulation, a pillared layered pore is modeled by a uniform distribution of pillars between two layered walls built by making two separate talc lamellas parallel each other with a given size of interlayer distance. The interaction between fluid molecules and two layered walls is measured by storing potentials calculated in advance at a series of grid points. The interaction between fluid molecules and pillars is also calculated by a site-to-site method. The potential model proposed in this work is proved to be effective because of the simulation result being good agreement with the experimental data for the adsorption of nitrogen at 77 K. Then, the adsorption isotherms of mixtures of short linear alkanes in pillared layered pores with three different porosities psi=0.98, 0.93 and 0.85, and three pore widths H=1.02, 1.70 and 2.38 nm at 300 K are obtained by taking advantage of the model. The simulation results tell us that the longer chain component is preferentially adsorbed at low pressures, and its adsorption increases and then decreases as the pressure increases while the shorter chain component is still adsorbed at high pressures. Moreover, the sorption selectivity of pillared layered materials for the longest chain component in alkane mixtures increases as the mole fraction of methane in the gas phase increases. The selectivity of pillared layered materials for the longest chain component in alkane mixtures also increases as the pore width decreases and the porosity increases. PMID:17482203

Li, Wen-Zhuo; Liu, Zi-Yang; Che, Yu-Liang; Zhang, Dan

2007-08-15

269

Detection and Monitoring of Stratigraphic Markers and Temperature Trends at the Greenland Ice Sheet Project 2 Using Passive-Microwave Remote-Sensing Data  

NASA Technical Reports Server (NTRS)

Satellite passive-microwave sensors provide a sensitive means of studying ice-sheet surface processes that assists ice-core interpretation and can extend local observations across regional scales. Analysis of special sensor microwave/imager (SSM/I) brightness temperature (TB) data supports ice-core research in two specific ways. First, the summer hoar complex layers used to date the Holocene portion of the Greenland Ice Sheet Project 2 ice core can be defined temporally and spatially by SSM/I 37-GHz vertically (V) and horizontally (H) polarized B ratio (V/H) trends. Second, comparison of automatic weather station temperatures to SSM/I 37-GHz V TB data shows that they are an effective proxy temperature record in this region. Also, the TB data can be correlated with proxy temperature trends from stable-isotope-ratio (delta O-18 and delta-D) profiles from snow pits and this allows the assignment of dates to specific snow depths.

Shuman, C. A.; Alley, R. B.; Fahnestock, M. A.; Fawcett, P. J.; Bondschadler, R. A.; White, J. W. C.; Grootes, P. M.; Anandakrishnan, S.; Stearns, C. R.

1997-01-01

270

Observed variability and trends in extreme temperature indices and rice-wheat productivity over two districts of Bihar, India—a case study  

NASA Astrophysics Data System (ADS)

The purpose of this paper is to analyze the trends and variability in extreme temperature indices and its impact on rice-wheat productivity over two districts of Bihar, India, which is part of the middle Indo-Gangetic Basin. Mann-Kendall non-parametric test was employed for detection of trend and Sen slope was determined to quantify the magnitude of such trends. We have analyzed 10 extreme temperature indices for monthly and seasonally. The influence of extreme temperature indices on rice-wheat productivity was determined using correlation analysis. As far as Patna is concerned, if the number of cool days during September ?10, the rice productivity will increase due to the availability of sufficient duration to fill up the grain. However, higher warm days during all the months except June will affect the productivity. A significant negative correlation was noticed between maximum value of minimum temperature during September and rice productivity. Highly significant positive correlation was noticed between number of cool days during September with rice productivity while it was highly significant negative correlation in the case of number of warm days during the same month. As far as Samastipur is concerned, a negative correlation was noticed between wheat productivity and maximum value of maximum temperature (TXx) during February, but not statistically significant. The higher temperature may affect the kernel weight and thereby yield. It is seen that a critical value of TXx ?29.2 °C will be harmful to wheat crop during February. A significant positive correlation of number of cool nights with wheat productivity also supports the above relationship. The critical values of extreme temperature indices during rice and wheat growing months provide an indicator to assess the vulnerability of rice-wheat productivity to temperature for Patna and Samastipur districts and there is a need to prepare an adaptive strategy and also develop thermo-insensitive rice-wheat high yielding varieties suitable for this region to sustain rice-wheat productivity under projected climate change situation.

Subash, N.; Singh, S. S.; Priya, Neha

2013-01-01

271

Trends of temperature and precipitation and their impact on grapewine phenology and production of in a Mediterranean vineyard region of Northeastern Spain  

NASA Astrophysics Data System (ADS)

The present analysis tries to contribute to the knowledge and impacts of climate change on agriculture, in particular in dryland areas of the Mediterranean NE Spain. The analysis was carried out in the Penedès region, located in Northeastern Spain (Barcelona province). In this area, vineyards have cultivated for centuries and at present represent about 80% of the cultivated area, most of them as rainfed agriculture, without irrigation. In order to analyse climate change impacts on grape development and production, the trends of daily rainfall and temperature were analyzed for the whole year and for the growing season, as well as some bioclimatic indexes (Hugling and Winkler index) using a long data set belonging to Vilafranca del Penedès for the period 1952-2006, and shorter series belonging to the observatories of Sant Sadurní d'Anoia, Sant Martí Sarroca, Els Hostalest de Pierola for the last 12 years (1996-2007). Phenology dates and production for the last 12 years for the main varieties cultivated in the area (Macabeo, Xarello, Parellada and Chardonnay) were analysed in relation to all the climatic analysed parameters. The study revealed warming trends with higher increases in the maximum temperatures (0.04°C/year) than in the minimum temperatures (0.03°C/year), and a significant increase in the number of days with temperatures higher than 30°C (0.43 days/year). Changes were also reproduced during the grape growing season. The increase of temperature has its influence on higher evapotranspiration ratios, which implies less effective water for crop development. Annual rainfall showed high variability from year to year and did not change significantly with time not at annual level either during the growing season. However, the precipitation of the main rainfall periods (spring and autumn) shows opposite trends, decreasing precipitation in spring and increasing in autumn. According to the vine phenological stages a significant decrease of precipitation during the bloom to véraison was observed (-0.33 mm/year), which presented a significant influence on grape production. The observed trends influence negatively grape development during the growing season, shortening the different phenological stages (véraison is advanced about 4 days/°C increase of Tmin) and decreasing yield for most of the main varieties cultivated in this area for white wine and cava production (Macabeo, Xarello, Parellada).

Ramos, M. C.; Jones, G. V.; Martínez-Casasnovas, J. A.

2009-04-01

272

Modelling and mapping spatio-temporal trends of heavy metal accumulation in moss and natural surface soil monitored 1990-2010 throughout Norway by multivariate generalized linear models and geostatistics  

NASA Astrophysics Data System (ADS)

Objective. This study explores the statistical relations between the accumulation of heavy metals in moss and natural surface soil and potential influencing factors such as atmospheric deposition by use of multivariate regression-kriging and generalized linear models. Based on data collected in 1995, 2000, 2005 and 2010 throughout Norway the statistical correlation of a set of potential predictors (elevation, precipitation, density of different land uses, population density, physical properties of soil) with concentrations of cadmium (Cd), mercury and lead in moss and natural surface soil (response variables), respectively, were evaluated. Spatio-temporal trends were estimated by applying generalized linear models and geostatistics on spatial data covering Norway. The resulting maps were used to investigate to what extent the HM concentrations in moss and natural surface soil are correlated. Results. From a set of ten potential predictor variables the modelled atmospheric deposition showed the highest correlation with heavy metals concentrations in moss and natural surface soil. Density of various land uses in a 5 km radius reveal significant correlations with lead and cadmium concentration in moss and mercury concentration in natural surface soil. Elevation also appeared as a relevant factor for accumulation of lead and mercury in moss and cadmium in natural surface soil respectively. Precipitation was found to be a significant factor for cadmium in moss and mercury in natural surface soil. The integrated use of multivariate generalized linear models and kriging interpolation enabled creating heavy metals maps at a high level of spatial resolution. The spatial patterns of cadmium and lead concentrations in moss and natural surface soil in 1995 and 2005 are similar. The heavy metals concentrations in moss and natural surface soil are correlated significantly with high coefficients for lead, medium for cadmium and moderate for mercury. From 1995 up to 2010 the modelled moss and natural surface soil estimates indicate a decrease of lead concentration in both moss and natural surface soil. In the case of the moss data the decrease of accumulation is more pronounced. By contrast, the modelled cadmium and mercury concentrations do not exhibit any significant temporal trend. Conclusions. In Europe, there is hardly any nation-wide investigation of statistical correlations between the accumulation of heavy metals in moss and natural surface soil and potential influencing factors such as atmospheric deposition. This study could show that assessments of heavy metal concentrations in natural surface soil could complement biomonitoring with moss but should not replace it since the heavy metal concentrations in mosses reliably traces the spatial pattern of respective atmospheric deposition. Generalized linear models extend established methods for estimating spatial patterns and temporal trends of HM concentration in moss and natural surface soil.

Nickel, Stefan; Hertel, Anne; Pesch, Roland; Schröder, Winfried; Steinnes, Eiliv; Uggerud, Hilde Thelle

2014-12-01

273

On the Temperature Dependence and Decadal Trends of Ozone in the San Joaquin Valley: Constraints from Measurements at the CalNex-Bakersfield Supersite  

NASA Astrophysics Data System (ADS)

Emissions and concentrations of organic molecules and nitrogen oxides (NOx) associated with passenger vehicles have been dramatically reduced over the last decade. In a recent analysis, Pusede and Cohen (2012) show that in California's San Joaquin Valley ozone has decreased in response to reductions in the organic reactivity (VOCR) at moderate temperatures throughout the Valley, but that at the hottest temperatures the effects of VOCR changes are modest or not at all apparent, particularly in the southern San Joaquin. To identify and quantify this uncontrolled, high-temperature VOCR source, we combine PAMS network measurements from six sites in the southern and central San Joaquin and the extensive suite of radical, trace gas, and reactivity observations collected in the summer of 2010 in Bakersfield during the CalNex field intensive. We find alcohols and aldehydes increase dramatically with temperature, becoming the largest contribution to VOCR of the observed organics. We also find evidence for a high-temperature VOCR source that is not accounted for by the available measurements of alcohols, aldehydes, and other organic molecules. Observations of total alkyl nitrates imply a very low nitrate yield per unit VOCR and provide an additional constraint on possible sources of this missing reactivity. We use these results to interpret inter-annual and temperature dependent trends in the frequency of ozone exceedances in the San Joaquin and to predict the response to additional VOCR and/or NOx emission controls in the region.

Pusede, S. E.; Gentner, D. R.; Wooldridge, P. J.; Browne, E. C.; Guha, A.; Goldstein, A. H.; Thomas, J.; Brune, W. H.; DiGangi, J. P.; Henry, S. B.; Keutsch, F. N.; Beaver, M. R.; St Clair, J. M.; Wennberg, P. O.; Cohen, R. C.

2012-12-01

274

Temperature dependence of non-linear capacitance in human embryonic kidney cells transfected with prestin, the outer hair cell motor protein.  

PubMed

The transmembrane motor protein prestin is thought to underlie outer hair cell (OHC) motility. Prestin expressed in non-auditory cells confers OHC-like electrical characteristics to the cell membrane, including the generation of gating-like currents (or non-linear capacitance), whose voltage dependence is susceptible to membrane tension and initial voltage conditions. Here we report that prestin's voltage sensitivity is, like that of the native motor, markedly temperature dependent. Prestin-transfected HEK cells were whole-cell voltage clamped while temperature was varied from 10-35 degrees C. V(pkcm), the voltage at peak capacitance, reversibly and linearly shifted to depolarized levels with increasing temperatures, while peak capacitance also increased, but with significant hysteresis upon recooling. Mathematical modeling suggests that this increase may be due to a charged voltage sensor having a wider range of movement through or larger unit charge within the plasma membrane at higher temperatures. PMID:11682147

Meltzer, J; Santos-Sacchi, J

2001-11-01

275

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

NASA Astrophysics Data System (ADS)

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 twentieth century Pacific SSTs is presented. By focusing on spatial and temporal recurrence, but without imposition of periodicity constraints, this single analysis discriminates between biennial, ENSO and decadal variabilities, leading to refined evolutionary descriptions; and between these natural variability modes and secular trend. Specifically, canonical ENSO variability is encapsulated in two modes that depict the growth and decay phases. Another interannual mode, energetic in recent decades, is shown linked to the west-to-east SST development seen in post--climate shift ENSOs: the non-canonical ESNO mode. Pacific decadal variability (PDV) is characterized by two modes: the Pan-Pacific mode has a horse-shoe structure with the closed end skirting the North American coast, and a quiescent eastern equatorial Pacific. The second decadal mode---the North Pacific mode---captures the 1976/77 climate shift and is closer to Mantua's Pacific Decadal Oscillation. Implicit accommodation of natural variability leads to a nonstationary SST trend, including midcentury cooling. These Pacific---and residual Atlantic---SST modes are then investigated for their connections to long-term hydroclimate variations over the Great Plains. During the Dust Bowl, dry anomalies in summer are found primarily linked to cool SSTs in the central tropical Pacific associated with non-canonical ENSO, as well as warm SSTs in the eastern tropical Atlantic associated with Atlantic Nino; in spring, however, dry anomalies are overwhelmed by connections to extratropical basins, when the cool phase of the SST trend coincided with a warm phase of the Atlantic Multidecadal Oscillation (AMO). Dry (wet) anomalies during the 1950s (1980s) are shown linked to the warm (cool) phase of the North Pacific decadal mode, as well as a warm (cool) AMO. The analysis suggests comparable importance of the Pacific and Atlantic Oceans in drought forcing, and highlights the role of the extratropical basins.

Guan, Bin

276

Influence of Chemical Cross-Linking on the Over Voltage Positive Temperature Coefficient of Linear Low Density Polyethylene\\/carbon Black\\/aluminum Hydroxide Nano Composites  

Microsoft Academic Search

The effect of cross-linking of blends on the stability of positive temperature coefficient (PTC) and the elimination of negative temperature coefficient (NTC) were investigated. Linear low density polyethylene (LLDPE) was chemically cross-linking with various amounts of dicumyl peroxide (DCP). The resulting of cross-linking structure of composites was analyzed by gel content, differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA).

C. Y. Huang; C. S. Tsai; K. Y. Tsao

2008-01-01

277

Estimation of the linear thermal expansion coefficient in friction-deposited, oriented poly(tetrafluoroethylene) films by temperature-dependent lateral force microscopy  

Microsoft Academic Search

Preliminary lateral force microscopy (LFM) results are presented which were obtained at different temperatures on thin films of poly(tetrafluoroethylene) prepared by friction deposition. Chain-chain distances of rodlike poly(tetrafluoroethylene) macromolecules were determined as a function of temperature from LFM images which exhibit molecular resolution. The value of the linear thermal expansion coefficient in the chain-perpendicular direction was estimated to be 3.5x10-3

Stefan Förster; Guobin Liu; G. Julius Vancso

1996-01-01

278

Trends in 1970-2010 summertime coastal California air temperatures:how HCN-corrections to COOP-data eliminated coastal-cooling  

NASA Astrophysics Data System (ADS)

The analysis of California COOP-site monthly-averaged summer Tmax-trends (1970-2005) by Lebassi et al. (2009, in J. of Climate) has been extended by: (a) lengthening the period to 2010, (b) trend-comparisons with newly released HCN data, and (c) calculation of trends in annual Tmax-values. HCN data sets are NCDC-homogenized subsets of the "most trusted" COOP sites; they include 12 (of the 52 COOP sites) in the San Francisco Bay Area and four (of 28) in the Southern California Air Basin (SoCAB). COOP data used as HCN1 data were adjusted by NCDC for the following biases: (a) time-of-observations, (b) spatial inhomogeneity, (c) missing values, (d) changes in thermometer type, and (e) urban warming, while HCN2 data do not include the last two corrections. Comparison of the 35- and 40-year COOP monthly-averaged Tmax-trends at the 16 HCN sites showed a high correlation (0.96). It also showed, however, that as the six inland warming-sites (COOP sites also HCN sites) of Lebassi et al. are now generally warming a slightly lower rate than five years ago, the seven comparable coastal-cooling sites are thus now generally cooling at a slightly lower rate. Coastal-cooling was shown by Lebassi et al. as a "reverse-reaction" to regional warming in inland areas, which triggers coastal sea breezes, and which thus increased cooling onshore flows. Comparison of HCN1 and COOP 35-year Tmax-trends shows little correlation (0.15), as the HCN1-corrections changed six of the seven COOP cooling-sites into HCN1 warming-sites. Only the site with largest original COOP cooling also showed HCN1 cooling. Similar comparisons between the COOP and HCN2 sites showed that HCN2-corrections changed fewer (only four) cooling-sites to warming (and with lower warming-rates); a low correlation (0.44) thus existed between trend-values. As many climate-change impacts (e.g., brown outs, heat stress, ozone peaks) depend on extreme Tmax-values, and not just averaged-monthly Tmax-values, the SoCAB distribution of the highest COOP Tmax-values anytime (at each of its 28 sites) during the period from 1970-2010 shows three sub-areas, with a boundary-temperature of 340C (and with the following ranges): (a) cool coastal (27-340C), (b) cool mountain-tops (28-340C), and (c) in-between hot-area (34-400C). The spatial distribution of the trends in these extreme Tmax-values show decreases up to -0.80C/dec in the coastal cooling areas and increases up to 0.60C/dec in the inland and mountain warming areas. Note that these trends are larger than the monthly-averaged Tmax-trends (about ±0.30C/dec) in Lebassi et al.

Bornstein, R. D.; Ghebreegziabher, A. T.; Lebassi, B.; González, J. E.

2011-12-01

279

Using temperature gradient gas chromatography to determine or predict vapor pressures and linear solvation energy relationship parameters of highly boiling organic compounds  

Microsoft Academic Search

An isothermal chromatographic method allowing determination of ??2H and ??2H descriptors of the linear solvation energy relationship (LSER) was tested and results obtained are presented. This method is based on the use of four stationary phases of various polarity. On the other hand, it was demonstrated that the temperature gradient chromatography may be successfully used to determine LSER descriptors. Results

F Mutelet; M Rogalski

2003-01-01

280

Orientation of Photosystem-I pigments: low temperature linear dichroism spectroscopy of a highly-enriched P700 particle isolated from spinach  

Microsoft Academic Search

The linear dichroism of Photosystem I particles containing 10 chlorophylls per P700 has been investigated at 10 K. The particles were oriented by uniaxial squeezing of polyacrylamide gels. The oxidation state of P700 was altered either by incubation of the gels with redox mediators or by low temperature illumination. The QY transitions of the primary electron donor P700, of the

Jacques Breton; Isaumu Ikegami

1989-01-01

281

Thermogravimetric determination of l-ascorbic acid in non-effervescent formulations using multiple linear regression with temperature selection by the successive projections algorithm  

Microsoft Academic Search

Changing experimental thermogravimetric conditions, such as heating rate and sample mass, may not be sufficient to eliminate the effect of interactions in pharmaceutical analysis. This motivates the investigation of a chemometric approach to determine active drugs in pharmaceutical formulations. The use of multiple linear regression (MLR) with temperatures selected by the successive projections algorithm (SPA) for determination of l-ascorbic acid

Rosa Lucia Simencio Otero; Roberto Kawakami Harrop Galvão; Mário César Ugulino Araújo; Éder Tadeu Gomes Cavalheiro

2011-01-01

282

Spring onset variations and trends in the continental United States: past and regional assessment using temperature-based indices  

USGS Publications Warehouse

Phenological data are simple yet sensitive indicators of climate change impacts on ecosystems, but observations have not been made routinely or extensively enough to evaluate spatial and temporal patterns across most continents, including North America. As an alternative, many studies use weather-based algorithms to simulate speci?c phenological responses. Spring Indices (SI) are a set of complex phenological models that have been successfully applied to evaluate variations and trends in the onset of spring across the Northern Hemisphere’s temperate regions. To date, SI models have been limited by only producing output in locations where both the plants’ chilling and warmth requirements are met. Here, we develop an extended form of the SI (abbreviated SI-x) that expands their application into the subtropics by ignoring chilling requirements while still retaining the utility and accuracy of the original SI (now abbreviated SI-o). The validity of the new indices is tested, and regional SI anomalies are explored across the data-rich continental United States. SI-x variations from 1900 to 2010 show an abrupt and sustained delay in spring onset of about 4–8 d (around 1958) in parts of the Southeast and southern Great Plains, and a comparable advance of 4–8 d (around 1984) in parts of the northern Great Plains and the West. Atmospheric circulation anomalies, linked to large-scale modes of variability, exert modest but signi?cant roles in the timing of spring onset across the United States on interannual and longer timescales. The SI-x are promising metrics for tracking spring onset variations and trends in mid-latitudes, relating them to relevant ecological, hydrological, and socioeconomic phenomena, and exploring connections between atmospheric drivers and seasonal timing.

Schwartz, Mark D.; Ault, Toby R.; Betancourt, Julio L.

2012-01-01

283

Reactivity trends of Fe phthalocyanines confined on graphite electrodes in terms of donor-acceptor intermolecular hardness: Linear versus volcano correlations  

NASA Astrophysics Data System (ADS)

In this work, we have studied the interaction between the hydrazine N2H4 molecule with several FeN4 macrocyclic complexes (FePc's). In order to modulate the electron density located on the metal center using iron-phthalocyanine (FePc) as the reference, we used substituted iron-phthalocyanines with different types of substituents electron-donating groups such as iron-tetraamino-phthalocyanine (4?(NH2)FePc) and iron-octamethoxyphthalocyanine (8?(OCH3)FePc), and with electron-withdrawing groups such as iron-tetranitrophthalocyanine(4?(NO2)FePc) and iron-hexadecachlorophthalocyanine (16(Cl)FePc), respectively. We have found that the energy of interaction between hydrazine and the Fe center in the macrocycle increases as the electron-withdrawing power of the substituents increases. When rate constants instead of currents are compared in a semilog plot versus ??D-A, a linear correlation is found where log k increases as the intermolecular hardness of the systems decreases.

Linares-Flores, C.; Espinoza-Vergara, J.; Zagal, J. H.; Arratia-Perez, R.

2014-10-01

284

Mechanical properties, glass transition temperature, and bond enthalpy trends of high metalloid Fe-based bulk metallic glasses  

E-print Network

-based bulk metallic glasses X. J. Gu,1 S. Joseph Poon,1,a Gary J. Shiflet,2 and Michael Widom3 1 Department transition temperatures Tg of Fe­Cr­Mo­P­C­B bulk metallic glasses containing up to 27 at. % metalloids have. The findings are relevant to understanding ductility and glass transition of metallic glasses. © 2008 American

Widom, Michael

285

Arctic\\/North Atlantic Oscillation signature in Holocene sea surface temperature trends as obtained from alkenone data  

Microsoft Academic Search

The variability in alkenone-derived sea surface temperatures (SSTs) in the North Atlantic realm shows that a continuous SST decrease in the northeast Atlantic from the early to the late Holocene was accompanied by a persistent warming over the western subtropical Atlantic, the eastern Mediterranean Sea and the northern Red Sea. Based on the analysis of the instrumental data and of

N. Rimbu; G. Lohmann; J.-H. Kim; H. W. Arz; R. Schneider

2003-01-01

286

Estimation of a diffusion model with trends taking into account the extremes. Application to temperature in France  

E-print Network

to temperature in France G. Benmenzer2 , D. Dacunha-Castelle1 , T.T.Huong Hoang1 [1] Laboratoire de Mathématiques and Artificial Intelligence Section Correspondence to: T.T.Huong Hoang (huong.hoang@math.u-psud.fr) SUMMARY. We in a simulation perspective. Discrete models linked to diffusions probably remain until to day the best class

Paris-Sud XI, Université de

287

Tree-ring derived Little Ice Age temperature trends from the central British Columbia Coast Mountains, Canada  

NASA Astrophysics Data System (ADS)

Most glaciers in the British Columbia Coast Mountains reached their maximum Holocene extent during the Little Ice Age. Early- and late-Little Ice Age intervals of expansion and retreat fluctuations describe a mass-balance response to changing climates. Although existing dendroclimatic records provide insights into these climatic fluctuations over the last 400 yr, their short durations prohibit evaluation of early-Little Ice Age climate variability. To extend the duration of these records, submerged coarse woody debris salvaged from a high-elevation lake was cross-dated to living chronologies. The resulting chronology provides the opportunity to reconstruct a regional June-July air-temperature anomaly record extending from AD 1225 to 2010. The reconstruction shows that the intervals AD 1350-1420, 1475-1550, 1625-1700 and 1830-1940 characterized distinct periods of below-average June-July temperature followed by periods of above-average temperature. Our reconstruction provides the first annually resolved insights into high-elevation climates spanning the Little Ice Age in this region and indicates that Little Ice Age moraine stabilization corresponds to persistent intervals of warmer-than-average temperatures. We conclude that coarse woody debris submerged in high-elevation lakes has considerable potential for developing lengthy proxy climate records, and we recommend that researchers focus attention on this largely ignored paleoclimatic archive.

Pitman, Kara J.; Smith, Dan J.

2012-11-01

288

Variations in surface ozone trends over Europe  

Microsoft Academic Search

Surface ozone data from 20 European stations of differing character (remote, rural, suburban and urban) were analyzed for linear trends over a common period of 1978-1988. Pronounced annual and seasonal variations are apparent in the trends in different areas. Relatively few of the trends are statistically significant and there is no dominant region-wide trend. However, there does appear to be

P. S. Low; P. M. Kelly; T. D. Davies

1992-01-01

289

Variations in surface ozone trends over Europe  

Microsoft Academic Search

Surface ozone data from 20 European stations of differing character (remote, rural, suburban and urban) were analysed for linear trends over a common period of 1978–1988. Pronounced annual and seasonal variations are apparent in the trends in different areas. Relatively few of the trends are statistically significant and there is no dominant region-wide trend. However, there does appear to be

P. S. Low; P. M. Kelly; T. D. Davies

1992-01-01

290

NASA trend analysis procedures  

NASA Technical Reports Server (NTRS)

This publication is primarily intended for use by NASA personnel engaged in managing or implementing trend analysis programs. 'Trend analysis' refers to the observation of current activity in the context of the past in order to infer the expected level of future activity. NASA trend analysis was divided into 5 categories: problem, performance, supportability, programmatic, and reliability. Problem trend analysis uncovers multiple occurrences of historical hardware or software problems or failures in order to focus future corrective action. Performance trend analysis observes changing levels of real-time or historical flight vehicle performance parameters such as temperatures, pressures, and flow rates as compared to specification or 'safe' limits. Supportability trend analysis assesses the adequacy of the spaceflight logistics system; example indicators are repair-turn-around time and parts stockage levels. Programmatic trend analysis uses quantitative indicators to evaluate the 'health' of NASA programs of all types. Finally, reliability trend analysis attempts to evaluate the growth of system reliability based on a decreasing rate of occurrence of hardware problems over time. Procedures for conducting all five types of trend analysis are provided in this publication, prepared through the joint efforts of the NASA Trend Analysis Working Group.

1993-01-01

291

Temperature Rise and Welding Characteristics of Ultrasonic Wire Bonding Using 190 kHz Linear, Circular and Square Vibration Loci and 600 kHz Linear Vibration Locus Welding Tips  

NASA Astrophysics Data System (ADS)

Welding characteristics of ultrasonic wire bonding using 190 kHz linear, circular and square vibration loci and a 600 kHz linear vibration locus are studied. High-frequency systems at 90 780 kHz have been shown to be significantly effective in comparison to a conventional system at 60 kHz. Aluminum wire welding specimens 0.1 mm in diameter have been successfully joined. Temperature increases at welding parts are measured from the thermoelectromotive force between the aluminum wire and copper plate specimens, and deformation at welded parts of wire specimens are measured using a digital height gage. Complex vibration welding tips at 190 kHz, which vibrate in elliptical to circular or rectangular to square shapes at either the same or different frequencies, are effective in joining welding specimens successfully in shorter welding times, under smaller vibration amplitudes and over wider good welding areas. A high-frequency 600 kHz system with a linear vibration locus is also effective for successful wire bonding. Both the temperature increase and wire deformation correlate well with the weld strength.

Tsujino, Jiromaru; Yoshihara, Hiroyuki; Itoh, Tomohiko; Inujima, Kazutoshi; Hirano, Yasuyuki

1998-05-01

292

Mann-Kendall trend of pollutants, temperature and humidity over an urban station of India with forecast verification using different ARIMA models.  

PubMed

The purpose of the present research is to identify the trends in the concentrations of few atmospheric pollutants and meteorological parameters over an urban station Kolkata (22° 32' N; 88° 20' E), India, during the period from 2002 to 2011 and subsequently develop models for precise forecast of the concentration of the pollutants and the meteorological parameters over the station Kolkata. The pollutants considered in this study are sulphur dioxide (SO2), nitrogen dioxide (NO2), particulates of size 10-?m diameters (PM10), carbon monoxide (CO) and tropospheric ozone (O3). The meteorological parameters considered are the surface temperature and relative humidity. The Mann-Kendall, non-parametric statistical analysis is implemented to observe the trends in the data series of the selected parameters. A time series approach with autoregressive integrated moving average (ARIMA) modelling is used to provide daily forecast of the parameters with precision. ARIMA models of different categories; ARIMA (1, 1, 1), ARIMA (0, 2, 2) and ARIMA (2, 1, 2) are considered and the skill of each model is estimated and compared in forecasting the concentration of the atmospheric pollutants and meteorological parameters. The results of the study reveal that the ARIMA (0, 2, 2) is the best statistical model for forecasting the daily concentration of pollutants as well as the meteorological parameters over Kolkata. The result is validated with the observation of 2012. PMID:24705814

Chaudhuri, Sutapa; Dutta, Debashree

2014-08-01

293

Seasonal trend of photosynthetic parameters and stomatal conductance of blue oak (Quercus douglasii) under prolonged summer drought and high temperature  

SciTech Connect

OAK-B135 Understanding seasonal changes in photosynthetic parameters and stomatal conductance is crucial for modeling long-term carbon uptake and energy fluxes of ecosystems. Gas exchange measurements of CO{sub 2} and light response curves on blue oak leaves (Quercus douglasii H. & A.) were conducted weekly throughout the growing season to study the seasonality of photosynthetic capacity (V{sub cmax}) and Ball-Berry slope (m) under prolonged summer drought and high temperature. A leaf photosynthetic model was used to determine V{sub cmax}. There was a pronounced seasonal pattern in V{sub cmax}. The maximum value of V{sub cmax}, 127 {micro}molm{sup -2} s{sup -1},was reached shortly after leaf expansion in early summer, when air temperature was moderate and soil water availability was high. Thereafter, V{sub cmax} declined as the soil water profile became depleted and the trees experienced extreme air temperatures, exceeding 40 C. The decline in V{sub cmax} was gradual in midsummer, however, despite extremely low predawn leaf water potentials ({Psi}{sub pd}, {approx} -4.0 MPa). Overall, temporal changes in V{sub cmax} were well correlated with changes in leaf nitrogen content. During spring leaf development, high rates of leaf dark respiration (R{sub d}, 5-6 {micro}mol m{sup -2} s{sup -1}) were observed. Once a leaf reached maturity, R{sub d} remained low, around 0.5 {micro}mol m{sup -2} s{sup -1}. In contrast to the strong seasonality of V{sub cmax}, m and marginal water cost per unit carbon gain ({partial_derivative}E/{partial_derivative}A) were relatively constant over the season, even when leaf {Psi}{sub pd} dropped to -6.8 MPa. The constancy of {partial_derivative}E/{partial_derivative}A suggests that stomata behaved optimally under severe water-stress conditions. We discuss the implications of our findings in the context of modeling carbon and water vapor exchange between ecosystems and the atmosphere.

Xu, L; Baldocchi, DD

2003-09-01

294

EMERGING TRENDS IN TREND RESEARCH  

Microsoft Academic Search

The competitive advantage of design business today is based on the ability to embed user values in products and being able to innovate according to social and cultural trends. In recent years, high competitiveness, market complexity and technological advances allow the trend process to be rapidly developed. In this paper, the fashion trend process is the central theme. The emerging

295

Trend and future of diesel engine: Development of high efficiency and low emission low temperature combustion diesel engine  

NASA Astrophysics Data System (ADS)

Stringent emission policy has put automotive research & development on developing high efficiency and low pollutant power train. Conventional direct injection diesel engine with diffused flame has reached its limitation and has driven R&D to explore other field of combustion. Low temperature combustion (LTC) and homogeneous charge combustion ignition has been proven to be effective methods in decreasing combustion pollutant emission. Nitrogen Oxide (NOx) and Particulate Matter (PM) formation from combustion can be greatly suppressed. A review on each of method is covered to identify the condition and processes that result in these reductions. The critical parameters that allow such combustion to take place will be highlighted and serves as emphasis to the direction of developing future diesel engine system. This paper is written to explore potential of present numerical and experimental methods in optimizing diesel engine design through adoption of the new combustion technology.

Ho, R. J.; Yusoff, M. Z.; Palanisamy, K.

2013-06-01

296

Bakken Shale Oil Production Trends  

E-print Network

drops below bubble point pressure and gas releasingout of the solution. With the Type II production trend, oil flows linearly from the matrix into the fracture system, either natural fracture or hydraulic fracture. Reservoir pressure is higher than...

Tran, Tan

2012-07-16

297

A Non-Linear, Non-Stationary Look at Oceanic-Land-Atmospheric Surface Temperature Variations over the Past 150 and 350 Years  

NASA Astrophysics Data System (ADS)

A study of the Global Surface Temperature Anomaly (GSTA) and separate records constituted by oceanic, atmospheric, land, global temperature records, reveals several things: 1)while the reported rise in global surface temperatures over the latter part of the 19th Century, though the 20th Century and into the 21st Century, has been viewed largely as an atmospheric phenomena, our study shows that the Global Ocean is the key player in regulating the Earth's temperature; 2)there is a rich multi-mode, multi-decade variability of planetary temperatures over the past 160 years, and in one individual record, back 350 years; 3)in the 350 year record, we find periods of both cooling and warming; and 4)over the past 150 years the temperature trend displays an overall warming. However our computed rate of warming is significantly different than that declared by the IPCC 2007 Report. Moreover, this analysis reveals that the foundational definitions of weather and climate should be revisited.

Pietrafesa, L. J.

2010-12-01

298

Lubricated Bearing Lifetimes of a Multiply Alkylated Cyclopentane and a Linear Perfluoropolyether Fluid in Oscillatory Motion at Elevated Temperatures in Ultrahigh Vacuum  

NASA Technical Reports Server (NTRS)

Bearing life tests in vacuum with three space liquid lubricants, two multiply alkylated cyclopentanes (MACs) and a linear perfluoropolyether (PFPE) were performed. Test conditions included: an 89 N axial load (mean Hertzian stress 0.66 GPa), vacuum level below 7x10(exp -4) Pa, and a +/-30deg dither angle. Dither rate was 75 cycles per minute. Higher (110 to 122 C) and lower temperature tests (75 C) were performed. For the higher temperature tests, the PFPE, Fomblin (Ausimont SpA) Z25 outperformed Pennzane (Shell Global Solutions) X-2000 by more than an order of magnitude. Lubricant evaporation played a key role in these high temperature results. At 75 C, the order was reversed with both Pennzane X-1000 and X-2000 outperforming Fomblin Z25 by more than an order of magnitude. Most Pennzane tests were suspended without failure. The primary failure mechanism in these lower temperature tests was lubricant consumption in the tribocontacts.

Braza, Joseph; Jansen, Mark J.; Jones, William R.

2009-01-01

299

Measurement of the temperature distribution within monodisperse combusting droplets in linear streams using two-color laser-induced fluorescence  

Microsoft Academic Search

Two-color laser-induced fluorescence can be use to perform space-averaged flying droplet temperature measurements. In this paper, the possibility to extend this technique to the measurement of the temperature distribution within a moving combusting droplet is considered and demonstrated. This technique may provide new experimental data related to the heat diffusion in liquid fuel droplets injected in high-temperature gas streams, for

G. Castanet; P. Lavieille; M. Lebouché; F. Lemoine

2003-01-01

300

Trends in Sea Ice Cover, Sea Surface Temperature, and Chlorophyll Biomass Across a Marine Distributed Biological Observatory in the Pacific Arctic Region  

NASA Astrophysics Data System (ADS)

The northern Bering and Chukchi Seas in the Pacific Arctic Region (PAR) are among the most productive marine ecosystems in the world and act as important carbon sinks, particularly during May and June when seasonal sea ice-associated phytoplankton blooms occur throughout the region. Recent dramatic shifts in seasonal sea ice cover across the PAR should have profound consequences for this seasonal phytoplankton production as well as the intimately linked higher trophic levels. In order to investigate ecosystem responses to these observed recent shifts in sea ice cover, the development of a prototype Distributed Biological Observatory (DBO) is now underway in the PAR. The DBO is being developed as an internationally-coordinated change detection array that allows for consistent sampling and monitoring at five spatially explicit biologically productive locations across a latitudinal gradient: (1) DBO-SLP (south of St. Lawrence Island (SLI)), (2) DBO-NBS (north of SLI), (3) DBO-SCS (southern Chukchi Sea), (4) DBO-CCS (central Chukchi Sea), and (5) DBO-BCA (Barrow Canyon Arc). Standardized measurements at many of the DBO sites were made by multiple research cruises during the 2010 and 2011 pilot years, and will be expanded with the development of the DBO in coming years. In order to provide longer-term context for the changes occurring across the PAR, we utilize multi-sensor satellite data to investigate recent trends in sea ice cover, chlorophyll biomass, and sea surface temperatures for each of the five DBO sites, as well as a sixth long-term observational site in the Bering Strait. Satellite observations show that over the past three decades, trends in sea ice cover in the PAR have been heterogeneous, with significant declines in the Chukchi Sea, slight declines in the Bering Strait region, but increases in the northern Bering Sea south of SLI. Declines in the persistence of seasonal sea ice cover in the Chukchi Sea and Bering Strait region are due to both earlier sea ice breakup and later sea ice formation. Sea surface temperatures have also shown warming, where sites show significant warming particularly during August, September, and October. Satellite-derived chlorophyll-a concentrations over the past decade have shown trends seemingly in direct response to changing sea ice conditions, with increasing trends in chlorophyll-a concentrations when sea ice declines (and vice versa). In some cases, however, satellite-derived chlorophyll-a concentrations do not show expected changes with sea ice variability, indicating that limitations on biological productivity in this region are complex and spatially heterogeneous. An understanding of these spatial and temporal complexities impacting biological productivity is needed for the accurate prediction of how overall ecosystems may be altered with further expected warming sea surface temperatures and declines in sea ice cover.

Frey, K. E.; Grebmeier, J. M.; Cooper, L. W.; Wood, C.; Panday, P. K.

2011-12-01

301

Evaluation of temperature gradients within combusting droplets in linear stream using two colors laser-induced fluorescence  

Microsoft Academic Search

The scope of this paper concerns the heating process of fuel droplets injected in a hot gaseous environment. The two colors laser-induced fluorescence technique allows measuring the temperature distribution within a droplet by scanning the droplet volume by a sufficiently small probe volume compared to the droplet volume itself. The temperature field is reconstructed using two approaches which have been

Guillaume Castanet; Alain Delconte; Fabrice Lemoine; Loïc Mees; Gèrard Gréhan

2005-01-01

302

Linear dimensional change, compressive strength and detail reproduction in type IV dental stone dried at room temperature and in a microwave oven  

PubMed Central

The type IV dental stone is widely used for the fabrication of dyes and master casts for fixed and removable partial prostheses. It is typically normal to wait at least 24 hours for the casts to dry prior to beginning the laboratory procedures. The waiting time has been shown to be greatly reduced by using microwave drying. Objective This study evaluated the influence of drying techniques at room temperature and microwave oven on the linear dimensional change, compressive strength and detail reproduction in type IV dental stones. Material and Methods Three type IV dental stone brands were selected; Elite Rock, Shera Premium and Durone IV. Two different drying protocols were tested in 4 groups (n=10); G1 - room temperature (25±4ºC) dried for 2 hours; G2 - room temperature dried for 24 hours; G3 - room temperature dried for 7 days and G4 - microwave oven dried at 800 W for 5 minutes and after 2 hours at room temperature. After drying, the samples were assayed for dimensional charges. The sample surface was submitted to the ImageTool 3.0 software for compressive strength in a universal testing machine with a cell load of 50 KN at a crosshead speed of 0.5 mm/minutes and the detail reproduction was analyzed with a stereomicroscope at 25x magnification. The statistical analysis of the linear dimensional change and compressive strength data were conducted by the ANOVA test followed by the Tukey test (p<0.05). Detailed reproduction values were reported in percentages. Results For the compressive strength test, Elite Rock and Durone IV did not present significant differences between G2 and G4, while Shera Premium did not present differences between G3 and G4. The best reproduction levels were observed for G3. Conclusions Dental stone microwave oven drying showed a linear dimensional change similar to after room temperature drying for 24 hours and 7 days. The compressive strength of the stone dried in the microwave oven was similar to those dried at room temperature for 24 hours, with the exception of Shera Premium, which had similar results for microwave and room temperature drying for 7 days. For the microwave drying method the detail reproduction levels for samples dried at room temperature for 24 hours and 7 days were similar, except for the Durone IV. PMID:23138748

da SILVA, Marcos Aurelio Bomfim; VITTI, Rafael Pino; CONSANI, Simonides; SINHORETI, Mario Alexandre Coelho; MESQUITA, Marcelo Ferraz; CONSANI, Rafael Leonardo Xediek

2012-01-01

303

Response of the summertime ground-level ozone trend in the Chicago area to emission controls and temperature changes, 2005-2013  

NASA Astrophysics Data System (ADS)

Despite strenuous efforts to reduce the emissions of ozone precursors such as nitrogen oxides (NOx), concentrations of ground-level ozone (O3) still often exceed the National Ambient Air Quality Standard in U.S. cities in summertime, including Chicago. Furthermore, studies have projected a future increase in O3 formation due to global climate change. This study examines the response of summertime O3 to emission controls and temperature change in the Chicago area from 2005 to 2013 by employing observations of O3, O3 precursors, and meteorological variables. We find that meteorology explains about 53% of the O3 variance in Chicago. O3 mixing ratios over Chicago are found to show no clear decline over the 2005-2013 period. The summertime ground-level O3 trend consists of a decrease of 0.08 ppb/year between 2005 and 2009 and an increase of 1.49 ppb/year between 2009 and 2013. Emissions of NOx and concentrations of NO2 have been decreasing steadily from 2005 to 2013 in the Chicago area. Concentrations of volatile organic compounds (VOCs) in Chicago, however, have more than doubled since 2009, even though emission inventories suggest that VOC emissions have decreased. We believe that O3 production in Chicago became more sensitive to VOCs starting in 2008/2009 and may have switched from being NOx-limited to VOC-limited. The warmer climate since 2008 has also contributed to the increasing ozone trend in the Chicago area. Increased attention should be paid to improving the quantification of VOC sources, enhancing the monitoring of reactive VOC concentrations, and designing VOC mitigation measures.

Jing, Ping; Lu, Zifeng; Xing, Jia; Streets, David G.; Tan, Qian; O'Brien, Timothy; Kamberos, Joseph

2014-12-01

304

Effect of the nonmonotonic temperature dependence of water density on free convection from a linear heat source  

Microsoft Academic Search

This paper presents the results of experimental studies of free convection from a heated wire in water for the two cases where\\u000a the water temperature is higher or lower than the temperature at which water has maximum density. It is shown that, in the\\u000a first case, the convective plume formed by heating rises, reaching the free surface. In the second

V. I. Bukreev; N. V. Gavrilov; A. V. Chebotnikov

2011-01-01

305

Influence of synthesis temperature on linear and nonlinear optical properties of water soluble luminescent Cd1-xZnxTe nanocrystals  

NASA Astrophysics Data System (ADS)

In This paper Cd1-xZnxTe nanocrystals were synthesized in aqueous phase, in presence of TGA as stabilizer. The samples have been characterized by X-ray diffraction (XRD) which confirmed that the alloyed nanocrystals were formed and crystal structure is FCC. The synthesis temperature effect on linear optical properties of the nanocrystals has been studied by UV-Vis absorption and Photoluminescence (PL) spectroscopy. It can be observed a red shift in emission and absorption peaks by increasing the synthesis temperature. All obtained samples display a narrow PL and sharp absorption spectra. Nonlinear indices of Cd1-xZnxTe nanocrystals were defined by the Z-scan technique using CW He-Ne laser (? = 632.8 nm). The results reveal that these nanoparticles exhibit strong NLO effect such as self-defocusing and two photon absorption. The Z-scan results show that by increasing the synthesis temperature, the nonlinear coefficients were reduced.

Gholami-Kaliji, S.; Saievar-Iranizad, E.; Dehghani, Z.; Majles-Ara, M. H.

306

Evaluation of temperature gradients within combusting droplets in linear stream using two colors laser-induced fluorescence  

NASA Astrophysics Data System (ADS)

The scope of this paper concerns the heating process of fuel droplets injected in a hot gaseous environment. The two colors laser-induced fluorescence technique allows measuring the temperature distribution within a droplet by scanning the droplet volume by a sufficiently small probe volume compared to the droplet volume itself. The temperature field is reconstructed using two approaches which have been compared. One is based on a geometrical optics model and the other is based on the 3D calculation of the internal excitation field within the droplet, using the generalized Lorenz-Mie theory. Experimental results have been obtained on a combusting monodisperse ethanol droplet stream (diameter around 200 ?m).

Castanet, Guillaume; Delconte, Alain; Lemoine, Fabrice; Mees, Loïc; Gréhan, Gèrard

2005-08-01

307

Finite-temperature dynamics of matter-wave dark solitons in linear and periodic potentials: An example of an antidamped Josephson junction  

NASA Astrophysics Data System (ADS)

We study matter-wave dark solitons in atomic Bose-Einstein condensates (BECs) at finite temperatures, under the effect of linear and periodic potentials. Our model, namely, a dissipative Gross-Pitaevskii equation, is treated analytically by means of dark-soliton perturbation theory and the Landau dynamics approach, which result in a Newtonian equation of motion for the dark-soliton center. This reduced model, which incorporates an effective washboard potential and an antidamping term accounting for finite-temperature effects, constitutes an example of an antidamped Josephson junction. We perform a qualitative (local and global) analysis of the equation of motion. We present results of systematic numerical simulations for both zero- and finite-temperature BECs to highlight the differences between the Hamiltonian and dissipative settings. For sufficiently small wave numbers of the periodic potential and weak linear potentials, the analytical results are found to be in good agreement with pertinent ones obtained via a Bogoliubov-de Gennes analysis and direct numerical simulations.

Shen, Y.; Kevrekidis, P. G.; Whitaker, N.; Karachalios, N. I.; Frantzeskakis, D. J.

2012-09-01

308

Research on the non-linear temperature field of molten metal shaped by an electromagnetic field in DS processing  

Microsoft Academic Search

A new directional solidification (DS) technique, combining electromagnetic shaping with liquid metal cooling, is established to confine and shape liquid metal by an electromagnetic field without the mold and carry out DS with a high-temperature gradient. The motion of the sample, heat radiation, and especially the material-property difference between the solid and the liquid, are considered for electromagnetic heating. Thereafter,

Jinshan Li; Qitang Hao; Shuangming Li; Hongchao Kou; Jianguo Li; Hengzhi Fu

2003-01-01

309

Electrothermal Design Procedure to Observe RF Circuit Power and Linearity Characteristics With a Homodyne Differential Temperature Sensor  

Microsoft Academic Search

The focus in this paper is on the extractio no f RF cir- cuit performance characteristics from the dc output of an on-chip temperature sensor. Any RF input signal can be applied to ex- cite the circuit under examination because only dissipated power levels are measured, which makes this approach attractive for on- line thermal monitoring and built-in test scenarios.

Marvin Onabajo; Josep Altet; Eduardo Aldrete-Vidrio; Diego Mateo; Jose Silva-Martinez

2011-01-01

310

On the multiscale nature of soil moisture-temperature couplings: the role of seasonality, causation and non-linear feedbacks in land-atmosphere interactions (Invited)  

NASA Astrophysics Data System (ADS)

Land-Atmosphere (L-A) interactions, their strength and directionality, are one of the main sources of uncertainty in current climate modeling, with strong implications on the accurate assessment of future climate variability and climate change impacts. Beside from the scarcity of direct observations, major uncertainties derive from the inherent complexity and nonlinearity of these interactions, and from their multi-scale character. Statistical analysis of L-A couplings is traditionally based on linear correlation methods and metrics. However, these approaches are not designed to detect causal connections or non-linear couplings and they poorly perform in presence of non-stationarities. Additionally these methods assess L-A couplings essentially in the time domain, despite the fact that L-A dynamical drivers can act simultaneously over a wide range of different space and time scales. This talk explores the multi-scale nature of L-A interactions, through the example of soil moisture-temperature couplings and soil-moisture memory effects. In several regions of the world, soil moisture can have a dampening effect on temperature due to evaporative cooling. By using spectral decomposition techniques and both newly developed satellite based products and re-analysis, we analyze the contribution of different time scales to the build-up of global soil moisture-temperature coupling hot spots, addressing at the same time the role of seasonality, causation and non-linear feedbacks in land-atmosphere interactions. Finally we focus on the role of fine (sub-monthly) time scales and their interplay with the seasonal scales.

Molini, A.; Casagrande, E.; Mueller, B.

2013-12-01

311

Advanced Review Tropospheric temperature trends  

E-print Network

for Climate and Satellites, NOAA National Climatic Data Center, 151 Patton Avenue, Asheville, NC, USA 3NOAA National Climatic Data Center, 151 Patton Avenue, Asheville, NC, USA 5 NOAA Air Resources Laboratory, 1315

312

A single-sided linear synchronous motor with a high temperature superconducting coil as the excitation system  

NASA Astrophysics Data System (ADS)

Thrust measurements were performed on a coil made of a YBa2Cu3O7 - ? coated conductor acting as the excitation system of a single-sided linear synchronous motor. The superconducting coil was a single pancake in the shape of a racetrack with 100 turns, the width and effective lengths were 42 mm and 84 mm, respectively. The stator was made of conventional copper wire. At 77 K and a gap of 10 mm, with an operating direct current of IDC = 30 A for the superconducting coil and alternating current of IAC = 9 A for the stator coils, a thrust of 24 N was achieved. With addition of an iron core, thrust was increased by 49%. With addition of an iron back-plate, thrust was increased by 70%.

Yen, F.; Li, J.; Zheng, S. J.; Liu, L.; Ma, G. T.; Wang, J. S.; Wang, S. Y.; Liu, Wei

2010-10-01

313

Trend and variability in observed hydrometeorological extremes in the Lake Victoria basin  

NASA Astrophysics Data System (ADS)

SummaryIn the Lake Victoria basin hydrology, trend analysis has mainly been limited to the mean of the hydrological variable without explicit consideration of extremes, which are very crucial in understanding the behaviour of disastrous hydrometeorological events. Since the effects of climate change are unleashed, more through the occurrence of extremes, analysis of both monotonic and cyclic trends in hydrological extremes is very crucial. The presence of a significant linear trend, in a long-term hydrometeorological record of extremes, may provide evidence of a shift from the natural trend to that which is enhanced by, for example, anthropogenic forcing. In addition, cyclic trends analysis of hydrological extremes provides information on the cyclic behaviour of the extreme anomalies that have occurred over and above the natural climate variability and may link them to past consequences and their drivers. Analysis of long term records of extremes for rainfall, temperature and streamflows for selected stations in the Lake Victoria basin, were carried out based on a linear trend test, to detect significant monotonic trends, and quantile perturbation analysis, to detect significant temporal extreme anomalies. In addition, correlations between change in rainfall extremes and that for the other extremes, as well as sunspot maxima, were investigated. The findings indicated that extremes in the Lake Victoria basin are, generally, experiencing positive linear trends. Albeit positive trend was generally demonstrated, the presence of significant linear trend was manifested in the extremes of the data obtained from the stations located in the northern and eastern parts of the Lake Victoria basin. This may suggest that the monotony in the positive trend is a result of an ever increasing and consistent external enhancement of the natural climate agitation. The latter has implications for flood risks if the trend persists in the near future. The cyclic analysis of the behaviour of extremes indicated that the 1940s and the 1970s experienced significantly low extremes. Furthermore, the higher significant anomalies for the 1990s, compared to that for the 1960s, may suggest a more intense enhancement of the change in the natural variability in the recent climate. Correlation between change in the extremes for rainfall and that of the minimum daily temperature was demonstrated to be stronger (c.f. maximum temperature and sunspot maxima) implying that if such correlation persists in the future then change in the extremes of daily minimum temperature can be used as an indicator for the change in rainfall extremes. The investigation of the correlations between climate indices/solar activity and hydrometeorological extremes suggests that oceanic and solar influences are part of the explanation of the variability observed in rainfall and temperatures extremes in the Lake Victoria basin.

Nyeko-Ogiramoi, P.; Willems, P.; Ngirane-Katashaya, G.

2013-05-01

314

Linear-temperature programmed pyrolysis of thermoresistant polymers — mass and FT-IR spectrometries Part 3. Poly(1,4-phenylene terephthalamide) and aromatic polyimides  

Microsoft Academic Search

Linear-temperature programmed pyrolysis (LTP-Py) has been applied to the investigation of the thermal degradation of poly(p-phenylene terephthalamide) (Twaron TM), poly(4,4?-phenyleneoxyphenylene pyromellitic imide) (Kapton), and poly(4,4?-phenyleneoxyphenylene-co-1, 3-phenylene-benzophenonetetracarboxylic diimide) (Pyralin PI-2555). Analytical methods were low-voltage electron-impact mass spectrometry (LV-EIMS) and Fourier transform-infrared (FT-IR spectroscopy). FT-IR with a heatable cell is apt for both evolved-gas analysis (EGA) and residue analysis, EIMS is more

D. O. Hummel; S. Göttgens; U. Neuhoff; H.-J. Düssel

1995-01-01

315

Identical temperature dependence of the time scales of several linear-response functions of two glass-forming liquids  

E-print Network

The frequency-dependent dielectric constant, shear and adiabatic bulk moduli, longitudinal thermal expansion coefficient, and longitudinal specific heat have been measured for two van der Waals glass-forming liquids, tetramethyl-tetraphenyl-trisiloxane (DC704) and 5-polyphenyl-4-ether. Within the experimental uncertainties the loss-peak frequencies of the measured response functions have identical temperature dependence over a range of temperatures, for which the Maxwell relaxation time varies more than nine orders of magnitude. The time scales are ordered from fastest to slowest as follows: Shear modulus, adiabatic bulk modulus, dielectric constant, longitudinal thermal expansion coefficient, longitudinal specific heat. The ordering is discussed in light of the recent conjecture that van der Waals liquids are strongly correlating, i.e., approximate single-parameter liquids.

Bo Jakobsen; Tina Hecksher; Kristine Niss; Tage Christensen; Niels Boye Olsen; Jeppe C. Dyre

2011-06-01

316

Communication: Identical temperature dependence of the time scales of several linear-response functions of two glass-forming liquids.  

PubMed

The frequency-dependent dielectric constant, shear and adiabatic bulk moduli, longitudinal thermal expansion coefficient, and longitudinal specific heat have been measured for two van der Waals glass-forming liquids, tetramethyl-tetraphenyl-trisiloxane (DC704) and 5-polyphenyl-4-ether. Within the experimental uncertainties the loss-peak frequencies of the measured response functions have identical temperature dependence over a range of temperatures, for which the Maxwell relaxation time varies more than nine orders of magnitude. The time scales are ordered from fastest to slowest as follows: Shear modulus, adiabatic bulk modulus, dielectric constant, longitudinal thermal expansion coefficient, and longitudinal specific heat. The ordering is discussed in light of the recent conjecture that van der Waals liquids are strongly correlating, i.e., approximate single-parameter liquids. PMID:22380025

Jakobsen, Bo; Hecksher, Tina; Christensen, Tage; Olsen, Niels Boye; Dyre, Jeppe C; Niss, Kristine

2012-02-28

317

Fertilizer trends.  

National Technical Information Service (NTIS)

This fourteenth edition of Fertilizer Trends presents historical fertilizer market data to aid industry, government, and financial market analysis and planners in their study of fertilizer and agricultural market cycles, market planning, and investment de...

R. Donaldson

1992-01-01

318

Statistical approach to the analysis of olive long-term pollen season trends in southern Spain.  

PubMed

Analysis of long-term airborne pollen counts makes it possible not only to chart pollen-season trends but also to track changing patterns in flowering phenology. Changes in higher plant response over a long interval are considered among the most valuable bioindicators of climate change impact. Phenological-trend models can also provide information regarding crop production and pollen-allergen emission. The interest of this information makes essential the election of the statistical analysis for time series study. We analysed trends and variations in the olive flowering season over a 30-year period (1982-2011) in southern Europe (Córdoba, Spain), focussing on: annual Pollen Index (PI); Pollen Season Start (PSS), Peak Date (PD), Pollen Season End (PSE) and Pollen Season Duration (PSD). Apart from the traditional Linear Regression analysis, a Seasonal-Trend Decomposition procedure based on Loess (STL) and an ARIMA model were performed. Linear regression results indicated a trend toward delayed PSE and earlier PSS and PD, probably influenced by the rise in temperature. These changes are provoking longer flowering periods in the study area. The use of the STL technique provided a clearer picture of phenological behaviour. Data decomposition on pollination dynamics enabled the trend toward an alternate bearing cycle to be distinguished from the influence of other stochastic fluctuations. Results pointed to show a rising trend in pollen production. With a view toward forecasting future phenological trends, ARIMA models were constructed to predict PSD, PSS and PI until 2016. Projections displayed a better goodness of fit than those derived from linear regression. Findings suggest that olive reproductive cycle is changing considerably over the last 30years due to climate change. Further conclusions are that STL improves the effectiveness of traditional linear regression in trend analysis, and ARIMA models can provide reliable trend projections for future years taking into account the internal fluctuations in time series. PMID:24361781

García-Mozo, H; Yaezel, L; Oteros, J; Galán, C

2014-03-01

319

Environmental trends  

SciTech Connect

The Council on Environmental Quality is required, by the National Environmental Policy Act of 1969, to report on the status and condition of the environment; current and foreseeable trends in the quality, management, and utilization of the environment; and the effects of environmental trends. The Council reports to Congress in an annual report and maintains an archive of national environmental statistics, which it updates and publishes periodically in the annual report as statistical tables and in environmental trends report as charts, graphs, and maps. Environmental Trends updates the Council's 1981 report by that name. This sourcebook contains 367 graphics, most of which are computer generated and indicate current conditions and trends in the environment of the United States. The statistical series for Environmental Trends was compiled from data available through government agencies, private studies, or thee literature of each discipline. The data were reviewed and verified by experts at various federal agencies. National data are used wherever possible, with breakdowns shown when especially meaningful. The text is drawn from the published sources cited. 367 figs.

Johnston, D.; Curtis, C.; Jens, J.C.; Kane, L. (eds.)

1989-01-01

320

Results from IODP Leg 306: Long-term cooling trend in North Atlantic sea-surface temperatures during the last 5 Ma  

NASA Astrophysics Data System (ADS)

In the early Pliocene global surface temperatures were several degrees warmer than today and ice sheets in the Northern Hemisphere had a limited extent [e.g., Haywood et al., 2005; Zachos et al., 2001]. This changed during the intensification of Northern Hemisphere glaciation (INHG) between 3.4 and 2.5 Ma (with a major step around 2.7 Ma), when global climate cooled and ice sheets in the Northern Hemisphere became more extensive [e.g., Zachos et al., 2001]. Here we present results from the first orbitally resolved (~ 4 ka resolution) record of Uk'37 based sea-surface temperature (SST) in the North Atlantic spanning the last 5 Ma. We used samples from the recently drilled IODP Site U1313, which is located in the North Atlantic at 41 oN and is a re-drill of DSDP Site 607. Our results show that the long-term cooling of SST in the North Atlantic began in the Early Pliocene around 4.1 Ma, which is earlier than previously thought. During the Pleistocene SST continued to cool and at the beginning of the mid-Pleistocene transition (MIS 40) glacial SST show a sudden drop to temperatures comparable to the LGM. At the same time the C37:4 alkenone, an indicator for arctic water masses [e.g., McClymont et al., 2008], became more abundant. We relate this to the influence of Arctic waters reaching far into the North Atlantic as the Arctic Front moved south during the peak glacial conditions of the Middle to Late Pleistocene. References: Haywood, A. M., P. Dekens, A. C. Ravelo, and M. Williams (2005), Warmer tropics during the mid-Pliocene? Evidence from alkenone paleothermometry and a fully coupled ocean-atmosphere GCM, Geochem. Geophys. Geosyst., 6(3), doi:10.1029/2004GC000799. McClymont, E. L., A. Rosell-Melé, G. H. Haug, and J. M. Lloyd (2008), Expansion of subarctic water masses in the North Atlantic and Pacific oceans and implications for mid-Pleistocene ice sheet growth, Paleoceanography, 23. Zachos, J., M. Pagani, L. Sloan, E. Thomas, and K. Billups (2001), Trends, Rhythms, and Aberrations in Global Climate 65 Ma to Present, Science, 292(5517), 686-693.

Naafs, David; Hefter, Jens; Stein, Ruediger; Haug, Gerald

2010-05-01

321

Non-linear thermal evolution of the crystal structure and phase transitions of LaFeO{sub 3} investigated by high temperature X-ray diffraction  

SciTech Connect

The crystal structure, anisotropic thermal expansion and structural phase transition of the perovskite LaFeO{sub 3} has been studied by high-temperature X-ray diffraction from room temperature to 1533 K. The structural evolution of the orthorhombic phase with space group Pbnm and the rhombohedral phase with R3{sup Macron }c structure of LaFeO{sub 3} is reported in terms of lattice parameters, thermal expansion coefficients, atomic positions, octahedral rotations and polyhedral volumes. Non-linear lattice expansion across the antiferromagnetic to paramagnetic transition of LaFeO{sub 3} at T{sub N}=735 K was compared to the corresponding behavior of the ferroelectric antiferromagnet BiFeO{sub 3} to gain insight to the magnetoelectric coupling in BiFeO{sub 3}, which is also multiferroic. The first order phase transition of LaFeO{sub 3} from Pbnm to R3{sup Macron }c was observed at 1228{+-}9 K, and a subsequent transition to Pm3{sup Macron }m was extrapolated to occur at 2140{+-}30 K. The stability of the Pbnm and R3{sup Macron }c polymorphs of LaFeO{sub 3} is discussed in terms of the competing enthalpy and entropy of the two crystal polymorphs and the thermal evolution of the polyhedral volume ratio V{sub A}/V{sub B}. - Graphical abstract: Aniostropic thermal evolution of the lattice parameters and phase transition of LaFeO{sub 3}. Highlights: Black-Right-Pointing-Pointer The crystal structure of LaFeO{sub 3} is studied by HTXRD from RT to 1533 K. Black-Right-Pointing-Pointer A non-linear expansion across the Neel temperature is observed for LaFeO{sub 3}. Black-Right-Pointing-Pointer The ratio V{sub A}/V{sub B} is used to rationalize the thermal evolution of the structure.

Selbach, Sverre M.; Tolchard, Julian R.; Fossdal, Anita [Department of Materials Science and Engineering, Norwegian University of Science and Technology, NO-7491 Trondheim (Norway)] [Department of Materials Science and Engineering, Norwegian University of Science and Technology, NO-7491 Trondheim (Norway); Grande, Tor, E-mail: grande@ntnu.no [Department of Materials Science and Engineering, Norwegian University of Science and Technology, NO-7491 Trondheim (Norway)] [Department of Materials Science and Engineering, Norwegian University of Science and Technology, NO-7491 Trondheim (Norway)

2012-12-15

322

A linear stability analysis on the onset of thermal convection of a fluid with strongly temperature-dependent viscosity in a spherical shell  

NASA Astrophysics Data System (ADS)

A linear stability analysis was performed in order to study the onset of thermal convection in the presence of a strong viscosity variation, with a special emphasis on the condition for the stagnant-lid (ST) convection where a convection takes place only in a sublayer beneath a highly viscous lid of cold fluid. We consider the temporal evolution (growth or decay) of an infinitesimal perturbation superimposed to a Boussinesq fluid with an infinite Prandtl number which is in a static (motionless) and conductive state in a basally heated planar layer or spherical shell. The viscosity of the fluid is assumed to be exponentially dependent on temperature. The linearized equations for conservations of mass, momentum, and internal (thermal) energy are numerically solved for the critical Rayleigh number, Ra c , as well as the radial profiles of eigenfunctions for infinitesimal perturbations. The above calculations are repeatedly carried out by systematically varying (i) the magnitude of the temperature dependence of viscosity, E, and (ii) the ratio of the inner and outer radii of the spherical shell, ?. A careful analysis of the vertical structure of incipient flows demonstrated that the dominance of the ST convection can be quantitatively identified by the vertical profile of ? h (a measure of conversion between horizontal and vertical flows), regardless of the model geometries. We also found that, in the spherical shell relevant to the Earth's mantle ( ? = 0.55), the transition into ST convection takes place at the viscosity contrast across the layer {r_?˜eq10^4} . Taken together with the fact that the threshold value of r ? falls in the range of r ? for a so-called sluggish-lid convection, our finding suggests that the ST-mode of convection with horizontally elongated convection cells is likely to arise in the Earth's mantle solely from the temperature-dependent viscosity.

Kameyama, Masanori; Ichikawa, Hiroki; Miyauchi, Arata

2013-02-01

323

TREND 2000  

NASA Technical Reports Server (NTRS)

The Educator Resource Center has created the Technology, Research, Education and Discovery (TREND) 2000 computer lab at NASA's John C. Stennis Space Center to facilitate the integration of technology into schools' curriculums by providing innovative and creative classroom strategies using state-of-the-art technology.

1996-01-01

324

Food Trends.  

ERIC Educational Resources Information Center

An overall perspective on trends in food consumption is presented. Nutrition awareness is at an all-time high; consumption is influenced by changes in disposable income, availability of convenience foods, smaller household size, and an increasing proportion of ethnic minorities in the population. (18 references) (LB)

Schwenk, Nancy E.

1991-01-01

325

Environmental Trends.  

ERIC Educational Resources Information Center

This document consists of data which highlight trends in all sectors relevant to environmental policy. These data are presented in the form of charts and maps contained in 13 sections under the following headings: people and the land; critical areas (wetlands, wild areas, parks, historic places, and risk zones); human settlements; transportation;…

Council on Environmental Quality, Washington, DC.

326

Mapping the boundary of the first order finite temperature restoration of chiral symmetry in the m_pi-m_K--plane with a linear sigma model  

E-print Network

The phase diagram of the three-flavor QCD is mapped out in the low mass corner of the m_pi-m_K--plane with help of the SU_L(3) x SU_R(3) linear sigma model (LSM). A novel zero temperature parametrization is proposed for the mass dependence of the couplings away from the physical point based on the the three-flavor chiral perturbation theory (U(3) ChPT). One-loop thermodynamics is constructed by applying optimized perturbation theory. The unknown dependence of the scalar spectra on the pseudoscalar masses limitates the accuracy of the predictions. Results are compared to lattice data and similar investigations with other variants of effective chiral models. The critical value of the pion mass is below 65 MeV for all m_K values <= 800 MeV. Along the diagonal m_pi=m_K, we estimate m_crit(diag)=40+-20 MeV.

T. Herpay; A. Patkos; Zs. Szep; P. Szepfalusy

2005-04-19

327

NASA standard: Trend analysis techniques  

NASA Technical Reports Server (NTRS)

Descriptive and analytical techniques for NASA trend analysis applications are presented in this standard. Trend analysis is applicable in all organizational elements of NASA connected with, or supporting, developmental/operational programs. This document should be consulted for any data analysis activity requiring the identification or interpretation of trends. Trend analysis is neither a precise term nor a circumscribed methodology: it generally connotes quantitative analysis of time-series data. For NASA activities, the appropriate and applicable techniques include descriptive and graphical statistics, and the fitting or modeling of data by linear, quadratic, and exponential models. Usually, but not always, the data is time-series in nature. Concepts such as autocorrelation and techniques such as Box-Jenkins time-series analysis would only rarely apply and are not included in this document. The basic ideas needed for qualitative and quantitative assessment of trends along with relevant examples are presented.

1990-01-01

328

Child Trends  

NSDL National Science Digital Library

A nonprofit research organization dedicated to improving the lives of children and their families, Child Trends conducts research and evaluation studies in areas including teenage pregnancy and childbearing, the effects of welfare and poverty on children, and parenting issues such as family structure and processes. A "one-stop shop for the latest trends in child and youth well-being," this Web site provides an extensive amount of information on youth issues, including essays and news releases, research briefs, fact sheets, and much more. Additionally, the site also contains a list of its current projects, categorized by research area. Easily navigable, this site is valuable for parents, social workers, teachers, child psychologists, and anyone else interested in youth related issues.

2002-01-01

329

Non-linear thermal evolution of the crystal structure and phase transitions of LaFeO3 investigated by high temperature X-ray diffraction  

NASA Astrophysics Data System (ADS)

The crystal structure, anisotropic thermal expansion and structural phase transition of the perovskite LaFeO3 has been studied by high-temperature X-ray diffraction from room temperature to 1533 K. The structural evolution of the orthorhombic phase with space group Pbnm and the rhombohedral phase with R3barc structure of LaFeO3 is reported in terms of lattice parameters, thermal expansion coefficients, atomic positions, octahedral rotations and polyhedral volumes. Non-linear lattice expansion across the antiferromagnetic to paramagnetic transition of LaFeO3 at TN=735 K was compared to the corresponding behavior of the ferroelectric antiferromagnet BiFeO3 to gain insight to the magnetoelectric coupling in BiFeO3, which is also multiferroic. The first order phase transition of LaFeO3 from Pbnm to R3barc was observed at 1228±9 K, and a subsequent transition to Pm3barm was extrapolated to occur at 2140±30 K. The stability of the Pbnm and R3barc polymorphs of LaFeO3 is discussed in terms of the competing enthalpy and entropy of the two crystal polymorphs and the thermal evolution of the polyhedral volume ratio VA/VB.

Selbach, Sverre M.; Tolchard, Julian R.; Fossdal, Anita; Grande, Tor

2012-12-01

330

Contrails, Cirrus Trends, and Climate  

Microsoft Academic Search

Rising global air traffic and its associated contrails have the potential for affecting climate via radiative forcing. Current estimates of contrail climate effects are based on coverage by linear contrails that do not account for spreading and, therefore, represent the minimum impact. The maximum radiative impact is estimated by assuming that long-term trends in cirrus coverage are due entirely to

Patrick Minnis; J. Kirk Ayers; Rabindra Palikonda; Dung Phan

2004-01-01

331

Exploring Linear Data  

NSDL National Science Digital Library

Created by Illuminations: Resources for Teaching Mathematics, students model linear data in a variety of settings that range from car repair costs to sports to medicine. Students will construct scatterplots of two-variable data; interpret individual data points; make conclusions about trends in data, especially linear relationships; and estimate and write equations of lines of best fit. The site offers insight into: learning objectives, materials needed, an instructional plan, assessment options, extensions, compliance with NCTM standards and expectations and even references to external sites.

2009-01-01

332

New Trends in Educational Lighting Systems.  

ERIC Educational Resources Information Center

Explores technological trends for improving campus lighting, including the use of direct-indirect suspended fluorescent lighting, suspended linear lighting, high-efficiency optical systems, and occupancy and daylight sensors. (GR)

Murphy, Peter

2001-01-01

333

Influence of urban heating on the global temperature land average using rural sites identified from MODIS classifications  

Microsoft Academic Search

The effect of urban heating on estimates of global average land surface temperature is studied by applying an urbanrural classification based on MODIS satellite data to the Berkeley Earth temperature data set compilation of 39,028 sites from 10 different publicly available sources. We compare the distribution of linear temperature trends for these sites to the distribution for a rural subset

Charlotte Wickham; Judith Curry; Don Groom; Robert Jacobsen; Richard Muller; Saul Perlmutter; Robert Rohde; Arthur Rosenfeld; Jonathan Wurtele

2011-01-01

334

Enriched-uranium feed costs for the High-Temperature Gas-Cooled reactor: trends and comparison with other reactor concepts  

Microsoft Academic Search

This report discusses each of the components that affect the unit cost for enriched uranium; that is, ore costs, UO to UF conversion cost, costs for enriching services, and changes in transaction tails assay. Historical trends and announced changes are included. Unit costs for highly enriched uranium (93.15 percent ²³U) and for low-enrichment uranium (3.0, 3.2, and 3.5 percent ²³U)

Thomas

1976-01-01

335

Propagation of ion-acoustic solitons in an electron beam-superthermal plasma system with finite ion-temperature: Linear and fully nonlinear investigation  

SciTech Connect

The propagation of ion-acoustic (IA) solitons is studied in a plasma system, comprised of warm ions and superthermal (Kappa distributed) electrons in the presence of an electron-beam by using a hydrodynamic model. In the linear analysis, it is seen that increasing the superthermality lowers the phase speed of the IA waves. On the other hand, in a fully nonlinear investigation, the Mach number range and characteristics of IA solitons are analyzed, parametrically and numerically. It is found that the accessible region for the existence of IA solitons reduces with increasing the superthermality. However, IA solitons with both negative and positive polarities can coexist in the system. Additionally, solitary waves with both subsonic and supersonic speeds are predicted in the plasma, depending on the value of ion-temperature and the superthermality of electrons in the system. It is examined that there are upper critical values for beam parameters (i.e., density and velocity) after which, IA solitary waves could not propagate in the plasma. Furthermore, a typical interaction between IA waves and the electron-beam in the plasma is confirmed.

Saberian, E. [Department of Physics, Faculty of Sciences, Azarbaijan Shahid Madani University, 53714-161 Tabriz (Iran, Islamic Republic of); Department of Physics, Faculty of Basic Sciences, University of Neyshabur, Neyshabur (Iran, Islamic Republic of); Esfandyari-Kalejahi, A.; Rastkar-Ebrahimzadeh, A.; Afsari-Ghazi, M. [Department of Physics, Faculty of Sciences, Azarbaijan Shahid Madani University, 53714-161 Tabriz (Iran, Islamic Republic of)

2013-03-15

336

Linear Algebra  

NSDL National Science Digital Library

This course provides an introduction to linear algebra. Topics include vector spaces, systems of linear equations, bases, linear independence, matrices, determinants, eigenvalues, inner products, quadratic forms and more. The course includes assignments, exams and study materials. MIT presents OpenCourseWare as free educational material online. No registration or enrollment is required to use the materials.

Ciubotaru, Dan

2010-12-28

337

Linear Accelerators  

NASA Astrophysics Data System (ADS)

In linear accelerators the particles are accelerated by either electrostatic fields or oscillating Radio Frequency (RF) fields. Accordingly the linear accelerators are divided in three large groups: electrostatic, induction and RF accelerators. Overview of the different types of accelerators is given. Stability of longitudinal and transverse motion in the RF linear accelerators is briefly discussed. The methods of beam focusing in linacs are described.

Sidorin, Anatoly

2010-01-01

338

Trend analysis of streamflow in Turkey  

Microsoft Academic Search

This paper presents trends computed for the 31-year period of monthly streamflows obtained from 26 basins over Turkey. Four non-parametric trend tests (the Sen's T, the Spearman's Rho, the Mann-Kendall, and the Seasonal Kendall which are known as appropriate tools in detecting linear trends of a hydrological time series) are adapted in this study. Moreover, the Van Belle and Hughes’

Ercan Kahya; Serdar Kalayc?

2004-01-01

339

Rainfall and rainy days trend in Iran  

Microsoft Academic Search

In this study, long-term annual and monthly trends in rainfall amount, number of rainy days and maximum precipitation in 24 h\\u000a are investigated based on the data collected at 33 synoptic stations in Iran. The statistical significance of trend and climate\\u000a variability is assessed by the Mann-Kendall test. The Linear trend analysis and the Mann-Kendall test indicate that there\\u000a are no

Saeed Soltani; R. Saboohi; L. Yaghmaei

2012-01-01

340

Trends in lake Rotorua water quality  

Microsoft Academic Search

Fourteen determinands relating to the water quality of Lake Rotorua were examined for trend over the period 1966–1983. A linear regression package was used, but additional manipulations were performed to eliminate markedly non?normal distributions, remove seasonality, compute monthly averages, fill gaps, and correct for serial correlation. Since lake data came from 3 different organisations, with possibly different analytical techniques, trends

J. C. Rutherford

1984-01-01

341

Linear Equations  

NSDL National Science Digital Library

This unit is a full lesson on linear equations with many problems for students and notes to teachers embedded. It begins with a question which illustrates the eight points students most often do not understand in order to answer it correctly. The unit is divided into ten sections: Characteristics of Linear Equations, Tables of Values for Graphing, Using Intercepts for Graphing, Using Slope-Intercept Form with Graphs, Families of Linear Equations, Graphing Linear vs. Non-Linear Equations, Creating, Graphing and Using Linear Equations, Simple System of Equations, What Went Wrong? (in which students observe how another student incorrectly answered a question), and Exploring with a Graphing Calculator. This is an excellent unit, used whole or in its parts, for students beginning with linear equations.

Czajkowski, Katrine

1997-01-01

342

The 20th century cooling trend over the southeastern United States  

NASA Astrophysics Data System (ADS)

Portions of the southern and southeastern United States, primarily Mississippi, Alabama, and Georgia, have experienced century-long (1895-2007) downward air temperature trends that occur in all seasons. Superimposed on them are shifts in mean temperatures on decadal scales characterized by alternating warm (1930s-1940s, 1990s) and cold (1900s; 1960s-1970s) regimes. Regional atmospheric circulation and SST teleconnection indices, station-based cloud cover and soil moisture (Palmer drought severity index) data are used in stepwise multiple linear regression models. These models identify predictors linked to observed winter, summer, and annual Southeastern air temperature variability, the observed variance (r2) they explain, and the resulting prediction and residual time series. Long-term variations and trends in tropical Pacific sea temperatures, cloud cover, soil moisture and the North Atlantic and Arctic oscillations account for much of the air temperature downtrends. Soil moisture and cloud cover are the primary predictors of 59.6 % of the observed summer temperature variance. While the teleconnections, cloud cover and moisture data account for some of the annual and summer Southeastern cooling trend, large significant downward trending residuals remain in winter and summer. Comparison is made to the northeastern United States where large twentieth century upward air temperature trends are driven by cloud cover increases and Atlantic Multidecadal Oscillation (AMO) variability. Differences between the Northeastern warming and the Southeastern cooling trends in summer are attributable in part to the differing roles of cloud cover, soil moisture, the Arctic Oscillation and the AMO on air temperatures of the 2 regions.

Rogers, Jeffrey C.

2013-01-01

343

Linear photon upconversion of 400 meV in an AlGaInP/GaInP quantum well heterostructure to visible light at room temperature  

E-print Network

Linear photon upconversion of 400 meV in an AlGaInP/GaInP quantum well heterostructure to visible online 17 April 2006 We linearly up convert photons from 820 to 650 nm, an energy change of 400 me American Institute of Physics. DOI: 10.1063/1.2195094 Photon energy upconversion devices absorb a low en

Russell, Kasey

344

Climatology and trends of the middle atmospheric temperature (33-87 km) as seen by Rayleigh lidar over the south of France  

Microsoft Academic Search

The technique of the Rayleigh lidar provides temperature profiles with a good temporal and vertical resolution in the middle atmosphere. Data obtained by 2 Rayleigh lidars set up at the Observatory of Haute-Provence (44°N, 6°E) and at Biscarrosse (44°N, 1°W) from 1978 to 1989 led to a unique set of data of 1200 night-mean temperature profiles from 37 to 87

Alain Hauchecorne; Marie-Lise Chanin; P. Keckhut

1991-01-01

345

Trends in furnace control  

SciTech Connect

This paper relates Italimpianti's experiences over the past few years in the area of control of reheat furnaces for the steel industry. The focus is on the level 1 area; specifically on the use of PLC-based systems to perform both combustion control and mechanical/hydraulic control. Some topics to be discussed are: overview of reheat furnace control system requirements; PLC only control vs separate PLC and DCS systems; PLC hardware requirements; man machine interface (MMI) requirements; purge, light-on and safety logic; implementation of more sophisticated level 1 control algorithms; furnace temperature optimization: look up tables vs full thermal modeling; and recent trends including integrated PLC/DCS system.

McDonald, T.J.; Keefe, M.D. (Italimpianti of America, Inc., Coraopolis, PA (United States). Instrumentation and Controls Dept.)

1993-07-01

346

Meteorologically adjusted ground level ozone trends in Ontario  

Microsoft Academic Search

Ground level ozone trends in Ontario are investigated with a regression model, assembled with parameters including a linear trend, seasonal variations, meteorological parameters and a categorical variable. The model has been applied to a number of data sets from southern Ontario and results show its capability of detecting ozone trends in the presence of meteorological fluctuations.

Dapeng Xu; David Yap; Peter A. Taylor

1996-01-01

347

Characterization of a hardened ultrastable UV linear variable filter and recent results on the radiometric stability of narrowband interference filters subjected to temperature\\/humidity, thermal\\/v  

Microsoft Academic Search

A series of in-band and out-of-band transmittance measurements of filters covering the wavelength range from 317 to 1019 nm and a linear variable filter for the 300 to 400 nm range have been made. The bandpass filters and the linear variable were fabricated using the ion-assisted- deposition or similar processes. The radiometric stability of the central wavelength, bandpass, and peak

Donald F. Heath; Ernest Hilsenrath; Scott J. Janz

1998-01-01

348

High-temperature ohmic contact to n-type 6H-SiC using nickel  

NASA Technical Reports Server (NTRS)

Specific contact resistances measured at elevated temperatures for Ni ohmic contacts to 6H-SiC were reported. The specific contact resistances were measured with the linear transmission line method at both room temperature and at 500 C and yielded values less than 5 x 10(exp -6) ohm sq cm at both temperatures. The trend shows a decreasing contact resistance at higher temperature. The annealed metal film is a nickel silicide with substantial mixing of C throughout the silicide layer.

Crofton, J.; Mcmullin, P. G.; Williams, J. R.; Bozack, M. J.

1995-01-01

349

Linear Motion Guide with Molybdenum Disulfide Composite Solid Lubricant  

NASA Astrophysics Data System (ADS)

The technical trend of solid lubricant rolling bearing and linear motion guide was reviewed. Especially, a newly developed oil-free solid lubricant linear motion guide by authors was also reported in details in this present. The rolling ball of the guide was coated by sputtering molybdenum disulfide (MoS2) and some special transition metal simultaneously, while the spacer ball made of polytetrafluoroethylene (PTFE) was also applied to the guide. By this way, a composite solid lubricant with excellent wear resistance properties was provided and there has been no any organic solvent and binder added, resulting in lower particle generation and low lever of out gas. It is expected that the oil-free solid lubricant linear motion guide could be applied to high temperature, high vacuum, radiation and space utilizations.

Yang, Hong; Takahashi, Tohru

350

Linear Functions  

NSDL National Science Digital Library

In this tutorial, "Linear functions of the form f(x) = ax + b and the properties of their graphs are explored interactively using an applet." The applet allows students to manipulate variables to discover the changes in intercepts and slope of the graphed line. There are six questions for students to answer, exploring the applet and observing changes. The questions' answers are included on this site. Additionally, a tutorial for graphing linear functions by hand is included.

Shodor

2012-03-29

351

The Integrated Status and Effectiveness Monitoring Program : Variation (Status and Trend) of Stream Water Temperature within th Entiat River Subbasin : January 2008 - October 2008.  

SciTech Connect

The Integrated Status and Effectiveness Monitoring Program (ISEMP - BPA project No.2003-017-00) has been created as a cost effective means of developing protocols and new technologies, novel indicators, sample designs, analytical, data management and communication tools and skills, and restoration experiments that support the development of a region-wide Research, Monitoring and Evaluation (RME) program to assess the status of anadromous salmonid populations, their tributary habitat and restoration and management actions. The most straightforward approach to developing a regional-scale monitoring and evaluation program would be to increase standardization among status and trend monitoring programs. However, the diversity of species and their habitat, as well as the overwhelming uncertainty surrounding indicators, metrics, and data interpretation methods, requires the testing of multiple approaches. Thus, the approach ISEMP has adopted is to develop a broad template that may differ in the details among subbasins, but one that will ultimately lead to the formation of a unified RME process for the management of anadromous salmonid populations and habitat across the Columbia River Basin. ISEMP has been initiated in three pilot subbasins, the Wenatchee/Entiat, John Day, and Salmon. To balance replicating experimental approaches with the goal of developing monitoring and evaluation tools that apply as broadly as possible across the Pacific Northwest, these subbasins were chosen as representative of a wide range of potential challenges and conditions, e.g., differing fish species composition and life histories, ecoregions, institutional settings, and existing data. ISEMP has constructed a framework that builds on current status and trend monitoring infrastructures in these pilot subbasins, but challenges current programs by testing alternative monitoring approaches. In addition, the ISEMP is: (1) Collecting information over a hierarchy of spatial scales, allowing for a greater flexibility of data aggregation for multi-scale recovery planning assessments, and (2) Designing methods that: (a) Identify factors limiting fish production in watersheds; (b) Determine restoration actions to address these problems; (c) Implement actions as a large-scale experiment (e.g. Before After Control Impact, or BACI design), and (d) Implement intensive monitoring and research to evaluate the action's success. The intent of the ISEMP project is to design monitoring programs that can efficiently collect information to address multiple management objectives over a broad range of scales. This includes: Evaluating the status of anadromous salmonids and their habitat; Identifying opportunities to restore habitat function and fish performance, and Evaluating the benefits of the actions to the fish populations across the Columbia River Basin. The multi-scale nature of this goal requires the standardization of protocols and sampling designs that are statistically valid and powerful, properties that are currently inconsistent across the multiple monitoring programs in the region. Other aspects of the program will aid in the ability to extrapolate information beyond the study area, such as research to elucidate causal mechanisms, and a classification of watersheds throughout the Columbia River Basin. Obviously, the scale of the problem is immense and the ISEMP does not claim to be the only program working towards this goal. As such, ISEMP relies heavily on the basin's current monitoring infrastructure to test and develop monitoring strategies, while acting as a coordinating body and providing support for key elements such as data management and technical analyses. The ISEMP also ensures that monitoring programs can address large-scale management objectives (resulting largely from the ESA) through these local efforts. While the ISEMP maintains a regional focus it also returns the necessary information to aid in management at the smaller spatial scales (individual projects) where manipulations (e.g., habitat restoration actions) actually occur. The work captur

Dawson, Pierre

2008-01-29

352

Geochemistry driven trends in microbial diversity and function across a temperature transect of a shallow water hydrothermal system off Milos (Greece)  

NASA Astrophysics Data System (ADS)

The shallow water hydrothermal vents off Milos Island, Greece, discharge hot, slightly acidic, reduced fluids into colder, slightly alkaline, oxygenated seawater. Gradients in temperature, pH, and geochemistry are established as the two fluids mix, leading to the formation of various microbial microniches. In contrast to deep-sea hydrothermal systems, the availability of sun light allows for a combination of photo- and chemotrophic carbon fixation. Despite the comparably easy accessibility of shallow water hydrothermal systems, little is known about their microbial diversity and functioning. We present data from a shallow hydrothermal system off Milos Island, one of the most hydrothermally active regions in the Mediterranean Sea. The physico-chemical changes from ambient seafloor to hydrothermal area were investigated and documented by in situ microsensor profiling of temperature, pH, total reduced sulfur and dissolved oxygen alongside porewater geochemistry. The spatial microbial diversity was determined using a combination of gene- and lipid-based approaches, whereas microbial functioning was assessed by stable isotope probing experiments targeting lipid biomarkers. In situ microprofiles indicated an extreme environment with steep gradients, offering a variety of microniches for metabolically diverse microbial communities. We sampled a transect along a hydrothermal patch, following an increase in sediment surface temperature from background to 90°C, including five sampling points up to 20 cm sediment depth. Investigation of the bacterial diversity using ARISA revealed differences in the community structure along the geochemical gradients, with the least similarity between the ambient and highly hydrothermally impacted sites. Furthermore, using multivariate statistical analyses it was shown that variations in the community structure could be attributed to differences in the sediment geochemistry and especially the sulfide content, and only indirectly to shifts in temperature. Results from intact polar lipid analyses were consistent with the ARISA data and clearly differentiated those samples located close to the vent from those found in less affected areas. Changes from phospho- and betaine lipids within the top layer of the unaffected area to glyco- and ornithine lipids in the hydrothermally influenced sediment layers reflected a change from photoautotrophic algae to a bacteria-dominated community as predominant lipid sources. A clear dominance of archaeal lipids indicated archaea as key players in the deeper, hotter layers of the hydrothermal sediment. We performed stable isotope probing experiments with 13C-bicarbonate in the dark to investigate if chemolithotrophy, as opposed to phototrophy, plays any significant role for carbon fixation in shallow vent systems. Different amendments revealed that not only chemolithotrophy represents an important pathway for carbon fixation in these ecosystems, but that diverse ways of dark CO2 fixation exist, with hydrogen being the most effective electron donor under high temperature conditions.

Bühring, Solveig I.; Amend, Jan P.; Gómez Sáez, Gonzalo V.; Häusler, Stefan; Hinrichs, Kai-Uwe; Pichler, Thomas; Pop Ristova, Petra; Price, Roy E.; Santi, Ioulia; Sollich, Miriam

2014-05-01

353

NASA standard: Trend analysis techniques  

NASA Technical Reports Server (NTRS)

This Standard presents descriptive and analytical techniques for NASA trend analysis applications. Trend analysis is applicable in all organizational elements of NASA connected with, or supporting, developmental/operational programs. Use of this Standard is not mandatory; however, it should be consulted for any data analysis activity requiring the identification or interpretation of trends. Trend Analysis is neither a precise term nor a circumscribed methodology, but rather connotes, generally, quantitative analysis of time-series data. For NASA activities, the appropriate and applicable techniques include descriptive and graphical statistics, and the fitting or modeling of data by linear, quadratic, and exponential models. Usually, but not always, the data is time-series in nature. Concepts such as autocorrelation and techniques such as Box-Jenkins time-series analysis would only rarely apply and are not included in this Standard. The document presents the basic ideas needed for qualitative and quantitative assessment of trends, together with relevant examples. A list of references provides additional sources of information.

1988-01-01

354

Linear Algebra  

NSDL National Science Digital Library

A mathematics professor from Saint Michael's College is the author of this free online textbook about linear algebra. Being just shy of 450 pages, the book is very comprehensive and of high quality. It gives an excellent introduction into topics such as vector spaces, linear systems, and determinants, and the author is quite good at defining a consistent notation throughout the book. Each chapter has several examples that demonstrate the concepts, concluding with exercises to be solved by the reader. Solutions to the exercises are given in a separate file. [CL

Hefferon, Jim.

355

Linearized elastic parameter sections  

SciTech Connect

Contrasts in elastic parameters can be estimated directly from seismic data using offset-dependent information in the PP reflection coefficient. A linear approximation to the PP reflection coefficient including three coefficients is fitted to the data, and relative contrasts in various elastic parameters are obtained from linear combinations of the estimated coefficients. Linearized elastic parameter sections for the contrasts in P-wave impedance, P-wave velocity, density, plane-wave modulus, and the change in bulk modulus and shear modulus normalized with the plane-wave modulus are estimated. If the average P- to S-wave velocity ratio is known, linearized parameter sections including the contrast in the average P- to S-wave velocity ratio and a fluid factor section can be computed. Applied to synthetic data, visual comparison of the estimated and true elastic parameter sections agree qualitatively, and the results are confirmed by an analysis of the standard deviation of the estimated parameters. The parameter sections obtained by inversion of a shallow seismic anomaly in the Barents Sea are promising, but the reliability is uncertain because neither well data nor regional trends are available.

Ursin, B.; Tjaaland, E. [Univ. of Trondheim (Norway); Ekren, B.O. [Statoil Research Center, Trondheim (Norway)

1996-05-01

356

Trend analysis in Turkish precipitation data  

Microsoft Academic Search

This study aims to determine trends in the long-term annual mean and monthly total precipitation series using non-parametric methods (i.e. the Mann-Kendall and Sen's T tests). The change per unit time in a time series having a linear trend was estimated by applying a simple non-parametric procedure, namely Sen's estimator of slope. Serial correlation structure in the data was accounted

Turgay Partal; Ercan Kahya

2006-01-01

357

Regional trends in rural sulfur concentrations  

NASA Astrophysics Data System (ADS)

This paper presents an analysis of trends in atmospheric concentrations of sulfur dioxide (SO 2) and particulate sulfate (SO 42-) at rural monitoring sites in the Clean Air Act Status and Trends Monitoring Network (CASTNet) from 1990 to 1999. A two-stage approach is used to estimate regional trends and standard errors in the Midwest and Mid-Atlantic regions of the US. In the first stage, a linear regression model is used to estimate site-specific trends in data adjusted for the effects of season and meteorology. In the second stage, kriging methodology based on maximum likelihood estimation is used to estimate regional trends and standard errors. The method is extended to include a Bayesian analysis to account for the uncertainty in estimating the spatial covariance parameters. For both pollutants, significant improvement in air quality was detected that appears similar to the large drop in SO 2 power plant emissions. Spatial patterns of trends in SO 2 and SO 42- concentrations vary by location over the eastern US. For SO 2, trends at monitoring sites in the Midwest and Mid-Atlantic were in the -30% to -42% range with smaller changes in the South. Across most of the US, trends in SO 42- were smaller than for SO 2. Both spatial prediction techniques produced similar results in terms of regional trends and standard errors.

Holland, David M.; Caragea, Petru t?a; Smith, Richard L.

358

5 World Oil Trends WORLD OIL TRENDS  

E-print Network

5 World Oil Trends Chapter 1 WORLD OIL TRENDS INTRODUCTION In considering the outlook for California's petroleum supplies, it is important to give attention to expecta- tions of what the world oil market. Will world oil demand increase and, if so, by how much? How will world oil prices be affected

359

Linear Algebra  

NSDL National Science Digital Library

This course, presented by MIT and taught by Professor Gilbert Strang, provides undergraduate level algebra instruction. The materials cover matrix theory and linear algebra including systems of equations, vector spaces, determinants, eigenvalues, similarity, and positive definite matrices. The course includes video lectures, assignments and exams (with solutions) and lecture notes. MIT presents OpenCourseWare as free educational material online. No registration or enrollment is required to use the materials.

Strang, Gilbert

2010-12-09

360

Linear Models  

NSDL National Science Digital Library

This site uses linear models to demonstrate the change in bird populations on a barren island over time, supply and demand, and the natural cleaning of a polluted lake by fresh water over time. The problems are laid out and turned into both graphic and equation form in order to understand the rate of change happening in each scenario. There are also links to previously covered materials that can help student review material from past math lessons.

Wattenberg, Frank

1997-01-01

361

Trends in the characteristics of allergenic pollen circulation in central Europe based on the example of Szeged, Hungary  

NASA Astrophysics Data System (ADS)

The aim of the study is to analyse trends of the pollination season with its start and end dates, as well as trends of the annual total pollen count and annual peak pollen concentration for the Szeged agglomeration in Southern Hungary. The data set covers an 11-year period (1999-2009) and includes one of the largest spectra, with 19 taxa, as well as seven meteorological variables (minimum-, maximum- and mean temperature, total radiation, relative humidity, rainfall and wind speed). For highly skewed data, such as the annual total number of pollen counts or annual peak pollen concentrations, the Mann-Kendall test has a substantially greater predictive power than the t-test. After performing Mann-Kendall tests, the annual cycles of daily slopes of pollen concentration trends and annual cycles of daily slopes of climate variable trends are calculated. This kind of trend analysis is a novel approach as it provides information on annual cycles of trends. In order to represent the strength of their relationships an association measure (AM) and a multiple association measure (MAM) are introduced. Based on climate sensitivity, the individual taxa are sorted into three categories. The results obtained for the pollen quantity and phenological characteristics are compared with two novel climate change related categories, namely risk and expansion potential due to the climate change for each taxon. The total annual pollen count and annual peak pollen concentrations indicate a small number of changes when using ordinary linear trends, while the total annual pollen count calculated via daily linear trends show significant trends (70% of them positive) for almost all taxa. However, except for Poaceae and Urtica, there is no significant change in the duration of the pollination season. The association measure performs well compared to the climate change related forces. Furthermore, remarkable changes in pollen season characteristics are also in accordance with the risk and expansion potential due to climate change.

Makra, László; Matyasovszky, István; Deák, Áron József

2011-10-01

362

Migration Trends Pittsburgh Region  

E-print Network

Migration Trends in the Pittsburgh Region 2000-2006 Christopher Briem July 2007 University of Pittsburgh UniversityCenterforSocialandUrbanResearch #12;Migration Trends in the Pittsburgh Region 2000...................................................................................................................3 3. Inter-regional Migration

Sibille, Etienne

363

Marketing Trends to Watch  

ERIC Educational Resources Information Center

This article identifies 13 cultural trends that libraries can turn into opportunites to reach patrons. These trends include: Twitter, online reputation management, value added content, mobile marketing, and emotional connection.

Circle, Alison

2009-01-01

364

Dinuclear complexes containing linear M-F-M [M = Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II)] bridges: trends in structures, antiferromagnetic superexchange interactions, and spectroscopic properties.  

PubMed

The reaction of M(BF(4))(2)·xH(2)O, where M is Fe(II), Co(II), Ni(II), Cu(II), Zn(II), and Cd(II), with the new ditopic ligand m-bis[bis(3,5-dimethyl-1-pyrazolyl)methyl]benzene (L(m)*) leads to the formation of monofluoride-bridged dinuclear metallacycles of the formula [M(2)(?-F)(?-L(m)*)(2)](BF(4))(3). The analogous manganese(II) species, [Mn(2)(?-F)(?-L(m)*)(2)](ClO(4))(3), was isolated starting with Mn(ClO(4))(2)·6H(2)O using NaBF(4) as the source of the bridging fluoride. In all of these complexes, the geometry around the metal centers is trigonal bipyramidal, and the fluoride bridges are linear. The (1)H, (13)C, and (19)F NMR spectra of the zinc(II) and cadmium(II) compounds and the (113)Cd NMR of the cadmium(II) compound indicate that the metallacycles retain their structure in acetonitrile and acetone solution. The compounds with M = Mn(II), Fe(II), Co(II), Ni(II), and Cu(II) are antiferromagnetically coupled, although the magnitude of the coupling increases dramatically with the metal as one moves to the right across the periodic table: Mn(II) (-6.7 cm(-1)) < Fe(II) (-16.3 cm(-1)) < Co(II) (-24.1 cm(-1)) < Ni(II) (-39.0 cm(-1)) ? Cu(II) (-322 cm(-1)). High-field EPR spectra of the copper(II) complexes were interpreted using the coupled-spin Hamiltonian with g(x) = 2.150, g(y) = 2.329, g(z) = 2.010, D = 0.173 cm(-1), and E = 0.089 cm(-1). Interpretation of the EPR spectra of the iron(II) and manganese(II) complexes required the spin Hamiltonian using the noncoupled spin operators of two metal ions. The values g(x) = 2.26, g(y) = 2.29, g(z) = 1.99, J = -16.0 cm(-1), D(1) = -9.89 cm(-1), and D(12) = -0.065 cm(-1) were obtained for the iron(II) complex and g(x) = g(y) = g(z) = 2.00, D(1) = -0.3254 cm(-1), E(1) = -0.0153, J = -6.7 cm(-1), and D(12) = 0.0302 cm(-1) were found for the manganese(II) complex. Density functional theory (DFT) calculations of the exchange integrals and the zero-field splitting on manganese(II) and iron(II) ions were performed using the hybrid B3LYP functional in association with the TZVPP basis set, resulting in reasonable agreement with experiment. PMID:23043562

Reger, Daniel L; Pascui, Andrea E; Smith, Mark D; Jezierska, Julia; Ozarowski, Andrew

2012-11-01

365

Global temperatures and sunspot numbers. Are they related? Yes, but non linearly. A reply to Gil-Alana et al. (2014)  

E-print Network

Gil-Alana et al. (Physica A: 396, 42-50, 2014) compared the sunspot number record and the temperature record and found that they differ: the sunspot number record is characterized by a dominant 11-year cycle while the temperature record appears to be characterized by a singularity or pole in the spectral density function at the zero frequency. Consequently, they claimed that the two records are characterized by substantially different statistical fractional models and rejected the hypothesis that sun influences significantly global temperatures. I show that: (1) the "singularity" or "pole" in the spectral density function of the global surface temperature at the "zero" frequency does not exist - it is a typical misinterpretation that discrete power spectra of non-stationary signals can suggest; (2) appropriate continuous periodograms clarify the issue and also show a signature of the 11-year solar cycle (amplitude <0.1 K), which since 1850 has an average period of about 10.4 year, and of many other natural...

Scafetta, Nicola

2014-01-01

366

Contemporary Trends power point  

E-print Network

Contemporary Trends and Leadership Challenges John Nalbandian www.goodlocalgovernment.org nalband@ku.edu Goals • Describe fundamental prerequisite for effective governance • Introduce two contemporary trends that widen the gap • Describe... must exist within political and administrative arenas and then between them Gap between Political Acceptability and Administrative Sustainability* Contemporary Trends • Administrative modernization • Create, maintain, preserve sense of community/identity Your Changes • Modernization...

Nalbandian, John

2013-02-01

367

Nonuniversal atmospheric persistence: Different scaling of daily minimum and maximum temperatures  

E-print Network

interference or it is a nor- mal ``excursion'' of the variable climate 1 . Each of the most elaborated global filter out nonstationarities such as slow trends. Variations in surface air temperature is obviously one,9,10,12,13 , shorter-time correlations are usually explained by using first- or second-order linear autoregres- sive

Jánosi, Imre M.

368

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

369

Multivariate trend testing of lake water quality  

Microsoft Academic Search

Multivariate methods of trend analysis offer the potential for higher power in detecting gradual water quality changes as compared to multiple applications of univariate tests. Simulation experiments were used to investigate the power advantages of multivariate methods for both linear model and Mann-Kendall based approaches. The experiments focused on quarterly observations of three water quality variables with no serial correlation

Jim C. Loftis; Charles H. Taylor; Avis D. Newell; Phillip L. Chapman

1991-01-01

370

Total solar irradiance trend during solar cycles 21 and 22  

Microsoft Academic Search

Results from Activity Cavity Radiometer Irradiance Monitor (ACRIM) experiments show an upward trend in total solar irradiance of 0.036 percent per decade between the minima of solar cycles 21 and 22. The trend follows the increasing solar activity of recent decades and, if sustained, could raise global temperatures. Trends of total solar irradiance near this rate have been implicated as

R. C. Willson

1997-01-01

371

Changes in Arctic sea ice concentration, 1988 to 1994, as detected using image trend analysis  

SciTech Connect

Arctic sea ice may prove to be an early indicator of global climatic change because of its high sensitivity to overlying air temperature and the predicted amplified response of the polar regions to a changing climate. Long term investigations into temporal change in variables such as Arctic sea ice concentration will prove to be even more significant as the accumulation of passive microwave remote sensing data continues. Hypertemporal image analysis techniques, of which image trend analysis is just one, provide methods for investigating spatial and temporal data trends through long image sequences. This study utilizes a Special Sensor Microwave/Imager dataset of monthly mean and anomaly sea ice concentrations to investigate changes in Arctic sea ice cover over seven years. The construction of a three dimensional hypertemporal image cube of the monthly data allows trends in ice concentration to be isolated through a linear regression analysis of all image pixels through the time series. The slope of the trend line for each pixel is assigned to a new image to show areas of negative and positive change through time. Use of monthly anomaly data deseasonalizes and removes autocorrelation from the mean monthly averages. The interpretation of results at a regional scale with no artificial boundaries applied highlights the spatial distribution of temporal trends in ice concentration within the natural climate system.

Derksen, C.; Piwowar, J.; Sokol, J.; LeDrew, E. [Univ. of Waterloo, Ontario (Canada)

1997-08-01

372

Linear modulator  

NASA Technical Reports Server (NTRS)

A study of frequency division multiplexing (FDM) systems was made for the purpose of determining the system performance that can be obtained with available state of the art components. System performance was evaluated on the basis of past experience, system analysis, and component evaluation. The system study was specifically directed to the area of FDM systems using subcarrier channel frequencies from 4 kHz to 200 kHz and channel information bandwidths of dc to 1, 2, 4, 8, and 16 kHz. The evaluation also assumes that the demodulation will be from a tape recorder which produces frequency modulation of + or - 1% on the signal due to the tape recorder wow and flutter. For the modulation system it is assumed that the pilot and carrier channel frequencies are stable to within + or - .005% and that the FM on the channel carriers is negligible. The modulator system was evaluated for the temperature range of -20 degree to +85 degree while the demodulator system was evaluated for operation at room temperature.

1972-01-01

373

Streamflow trends in Nepal  

Microsoft Academic Search

This study presents the first comprehensive nationwide trend detection of streamflow in Nepal, a country that has been historically understudied despite its critical location as the southern pathway for most of the Himalayan snowpack melt and torrential seasonal monsoon rains. We applied Mann-Kendall and Sen's trend tests using trend-free pre-whitening and bootstrap approaches to two streamflow data sets to deal

M. R. Gautam; K. Acharya

2012-01-01

374

Streamflow trends in Switzerland  

Microsoft Academic Search

Mean daily streamflow records from 48 watersheds in Switzerland with an undisturbed runoff regime are analysed for trends with the Mann–Kendall nonparametric test in three study periods (1931–2000, 1961–2000, 1971–2000). The statistical significance of trends is tested for each station on an annual and seasonal basis and for different streamflow quantiles. The field significance of trends is tested by a

Marius-Victor Birsan; Peter Molnar; Paolo Burlando; Martin Pfaundler

2005-01-01

375

EPA - Air Trends Reports  

NSDL National Science Digital Library

This site provides annual reports on air pollution trends in the United States issued by the U.S. Environmental Protection Agency. These reports are directed to both the technical air pollution audience and other interested parties. Air quality topics include visibility trends, Ozone monitoring, toxins, and trends in specific regions. The reports are complete with all accompanying tables and figures. Each chapter can be downloaded separately.

2004-06-15

376

Regional Kendall test for trend  

USGS Publications Warehouse

Trends in environmental variables are often investigated within a study region at more than one site. At each site, a trend analysis determines whether a trend has occurred. Yet often also of interest is whether a consistent trend is evident throughout the entire region. This paper adapts the Seasonal Kendall trend test to determine whether a consistent regional trend occurs in environmental variables.

Helsel, D.R.; Frans, L.M.

2006-01-01

377

Optimal linear Glauber model  

E-print Network

Contrary to the actual nonlinear Glauber model (NLGM), the linear Glauber model (LGM) is exactly solvable, although the detailed balance condition is not generally satisfied. This motivates us to address the issue of writing the transition rate ($w_j$) in a best possible linear form such that the mean squared error in satisfying the detailed balance condition is least. The advantage of this work is that, by studying the LGM analytically, we will be able to anticipate how the kinetic properties of an arbitrary Ising system depend on the temperature and the coupling constants. The analytical expressions for the optimal values of the parameters involved in the linear $w_j$ are obtained using a simple Moore-Penrose pseudoinverse matrix. This approach is quite general, in principle applicable to any system and can reproduce the exact results for one dimensional Ising system. In the continuum limit, we get a linear time-dependent Ginzburg-Landau (TDGL) equation from the Glauber's microscopic model of non-conservative dynamics. We analyze the critical and dynamic properties of the model, and show that most of the important results obtained in different studies can be reproduced by our new mathematical approach. We will also show in this paper that the effect of magnetic field can easily be studied within our approach; in particular, we show that the inverse of relaxation time changes quadratically with (weak) magnetic field and that the fluctuation-dissipation theorem is valid for our model.

Shaon Sahoo; Soumya Kanti Ganguly

2014-01-21

378

Trend analysis using non-stationary time series clustering based on the finite element method  

NASA Astrophysics Data System (ADS)

In order to analyze low-frequency variability of climate, it is useful to model the climatic time series with multiple linear trends and locate the times of significant changes. In this paper, we have used non-stationary time series clustering to find change points in the trends. Clustering in a multi-dimensional non-stationary time series is challenging, since the problem is mathematically ill-posed. Clustering based on the finite element method (FEM) is one of the methods that can analyze multidimensional time series. One important attribute of this method is that it is not dependent on any statistical assumption and does not need local stationarity in the time series. In this paper, it is shown how the FEM-clustering method can be used to locate change points in the trend of temperature time series from in situ observations. This method is applied to the temperature time series of North Carolina (NC) and the results represent region-specific climate variability despite higher frequency harmonics in climatic time series. Next, we investigated the relationship between the climatic indices with the clusters/trends detected based on this clustering method. It appears that the natural variability of climate change in NC during 1950-2009 can be explained mostly by AMO and solar activity.

Gorji Sefidmazgi, M.; Sayemuzzaman, M.; Homaifar, A.; Jha, M. K.; Liess, S.

2014-05-01

379

Confinement effects on glass transition temperature, transition breadth, and linear expansivity: an ultraslow X-ray reflectivity study on supported ultrathin polystyrene films.  

PubMed

X-ray reflectivity measurements of the glass transition in thin polystyrene films supported on Si substrates were performed at slow cooling rates ranging from 0.62 to 0.01 (°)C/min. At a cooling rate of 0.14 (°)C/min, a depression in the glass transition temperature Tg was clearly observed with decreasing thickness. However, at a cooling rate of 0.62 (°)C/min, only a slight decrease in Tg for a 12-nm-thick film was observed, while at an ultraslow cooling rate of 0.01 °C/min, a significant reduction in the Tg of ultrathin films (12 and 6 nm) was observed. As the thickness decreased, a broadening in the width of the glass transition, w, was found at higher cooling rates (0.62 °C/min and 0.14 °C/min), while narrowing of w was observed at ultraslow cooling rates of 0.01 °C/min and 0.04 °C/min. A narrow distribution of relaxation time in the ultrathin films indicates that most segments are able to relax under the ultraslow cooling process, thus showing an inherent reduction in the Tg of the confined thin polymer films. PMID:23807467

Yang, Chunming; Onitsuka, Rena; Takahashi, Isao

2013-06-01

380

Reliability of regional climate model trends  

NASA Astrophysics Data System (ADS)

A necessary condition for a good probabilistic forecast is that the forecast system is shown to be reliable: forecast probabilities should equal observed probabilities verified over a large number of cases. As climate change trends are now emerging from the natural variability, we can apply this concept to climate predictions and compute the reliability of simulated local and regional temperature and precipitation trends (1950-2011) in a recent multi-model ensemble of climate model simulations prepared for the Intergovernmental Panel on Climate Change (IPCC) fifth assessment report (AR5). With only a single verification time, the verification is over the spatial dimension. The local temperature trends appear to be reliable. However, when the global mean climate response is factored out, the ensemble is overconfident: the observed trend is outside the range of modelled trends in many more regions than would be expected by the model estimate of natural variability and model spread. Precipitation trends are overconfident for all trend definitions. This implies that for near-term local climate forecasts the CMIP5 ensemble cannot simply be used as a reliable probabilistic forecast.

van Oldenborgh, G. J.; Doblas Reyes, F. J.; Drijfhout, S. S.; Hawkins, E.

2013-03-01

381

Reliability of regional climate model trends  

NASA Astrophysics Data System (ADS)

A necessary condition for a good probabilistic forecast is that the forecast system is shown to be reliable: forecast probabilities should equal observed probabilities verified over a large number of cases. As climate change trends are now emerging from the natural variability, we can apply this concept to climate predictions and compute the reliability of simulated local and regional temperature and precipitation trends (1950-2011) in a recent multi-model ensemble of climate model simulations prepared for the Intergovernmental Panel on Climate Change (IPCC) fifth assessment report (AR5). With only a single verification time, the verification is over the spatial dimension. The local temperature trends appear reliable. However, when the global mean climate response is factored out, the ensemble is overconfident: the observed trend is outside the range of modelled trends in many more regions than would be expected by natural variability and model spread. Precipitation trends are overconfident for all trend definitions. This implies that for near-term local climate forecasts the CMIP5 ensemble cannot simply be used as a reliable probabilistic forecast.

van Oldenborgh, Geert Jan; Doblas-Reyes, Francisco; Drijfhout, Sybren; Hawkins, Ed

2013-04-01

382

Short-term Aerosol Trends: Reality or Myth?  

NASA Technical Reports Server (NTRS)

The main questions addressed in this slide presentation involve short-term trends of MODIS aerosol optical thickness (AOT) over 6 years: (1) Why are the trends different in different regions? (2) How are these trends so high? (3) Why are they "coherent" in many areas? (4) Are these changes in aerosol concentrations real, i.e., are they monotonic changes in emissions? Several views of the Spatial Distribution of AOT from Terra are shown. In conclusion there are several trends: (1) There is a broad spatial inhomogenueity in AOT trends over 6 years of MODIS Terra and Aqua (2) Some of the areas demonstrate clear positive trends related to increase of emission (e.g., Eastern China) (3) Strong trends in some other areas are superficial and might be attributed, in part, to: (3a) Least squares linear trend sensitivity to outliers (need to use more robust linear fitting method) (3b) Spatial and temporal shifts or trends in meteorological conditions, especially in wind patterns responsible for aerosol transport (6) Aerosol trends should be studied together with changes in meteorology patterns as they might closely linked together

Leptoukh, Gregory; Zubko, Viktor

2009-01-01

383

Glass transition temperature of a cationic polymethacrylate dependent on the plasticizer content - Simulation vs. experiment  

NASA Astrophysics Data System (ADS)

Atomistic molecular dynamics simulations ( NPT ensemble) are performed to compute the specific volume as a function of temperature of cationic polymethacrylate (Eudragit ® RS) with varying plasticizer (triethylcitrate) content ranging from pure polymer to a plasticizer weight proportion of 7.70%. The simulated glass transition temperature of these polymer-plasticizer blends is determined as the temperature marking the kink in the slope of specific volume vs. temperature plots. A linear dependence of the glass transition temperature on the plasticizer content is found. The computational findings are supported by differential scanning calorimetry experiments showing the same trend thus validating the applied computational method.

Wagner, Karl G.; Maus, Martin; Kornherr, Andreas; Zifferer, Gerhard

2005-04-01

384

A non linear ADC for sensor linearization  

Microsoft Academic Search

A successive approximation ADC with nonlinear characteristic is presented as an effective method for sensor linearization. Drastic simplification of the ADC structure was obtained by implementing a piece wise linear approximation of the required non linear curve. The design and simulated performance of an 8-bit prototype, applied to the linearization of a real flow sensor, are presented.

Emilio Volpi; Nicolò Nizza; Paolo Bruschi

2007-01-01

385

General Achievement Trends: Connecticut  

ERIC Educational Resources Information Center

This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

Center on Education Policy, 2009

2009-01-01

386

General Achievement Trends: Pennsylvania  

ERIC Educational Resources Information Center

This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

Center on Education Policy, 2009

2009-01-01

387

General Achievement Trends: Montana  

ERIC Educational Resources Information Center

This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

Center on Education Policy, 2009

2009-01-01

388

General Achievement Trends: Massachusetts  

ERIC Educational Resources Information Center

This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

Center on Education Policy, 2009

2009-01-01

389

General Achievement Trends: Michigan  

ERIC Educational Resources Information Center

This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

Center on Education Policy, 2009

2009-01-01

390

General Achievement Trends: Maryland  

ERIC Educational Resources Information Center

This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

Center on Education Policy, 2009

2009-01-01

391

General Achievement Trends: Arizona  

ERIC Educational Resources Information Center

This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

Center on Education Policy, 2009

2009-01-01

392

General Achievement Trends: Alabama  

ERIC Educational Resources Information Center

This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

Center on Education Policy, 2009

2009-01-01

393

General Achievement Trends: Kansas  

ERIC Educational Resources Information Center

This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

Center on Education Policy, 2009

2009-01-01

394

General Achievement Trends: Idaho  

ERIC Educational Resources Information Center

This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

Center on Education Policy, 2009

2009-01-01

395

General Achievement Trends: Virginia  

ERIC Educational Resources Information Center

This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

Center on Education Policy, 2009

2009-01-01

396

General Achievement Trends: Louisiana  

ERIC Educational Resources Information Center

This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

Center on Education Policy, 2009

2009-01-01

397

General Achievement Trends: Ohio  

ERIC Educational Resources Information Center

This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

Center on Education Policy, 2009

2009-01-01

398

Twitter Trending Topic Classification  

Microsoft Academic Search

With the increasing popularity of microblogging sites, we are in the era of information explosion. As of June 2011, about 200 million tweets are being generated everyday. Although Twitter provides a list of most popular topics people tweet about known as Trending Topics in real time, it is often hard to understand what these trending topics are about. Therefore, it

Kathy Lee; Diana Palsetia; Ramanathan Narayanan; Ankit Agrawal; Alok Choudhary

2011-01-01

399

Some Current Population Trends.  

ERIC Educational Resources Information Center

Population trends in the 1960's and early 1970's are examined in this 1972 speech in terms of overall national trends, the growth of metropolitan areas, the rural population, geographic shifts, internal migration, the black population, and living arrangements. It is noted that population growth in the 1960's was unevenly distributed within age…

Taeuber, Conrad

400

General Achievement Trends: Nebraska  

ERIC Educational Resources Information Center

This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

Center on Education Policy, 2009

2009-01-01

401

Linear vs. Non-Linear Earthquake Location and Seismogenic Fault Detection in the Southern Tyrrhenian Sea, Italy  

NASA Astrophysics Data System (ADS)

We report a comparison between the performances of linearized and non-linear hypocenter location algorithms working in 3D velocity structures. For this purpose, we used the SIMUL linearized location method by Evans et al. (1994) and the BAYLOC non-linear grid-search probabilistic algorithm by Presti et al. (2004). Comparisons are made using the datasets of P and S readings relative to the two main seismic sequences occurring in the last ten years in the southern Tyrrhenian sea, i.e. the 1998 sequence of maximum magnitude 5.2 near Ustica island and the 2002 sequence of max. magnitude 5.9 offshore Palermo city. We find that in the relatively poor network conditions of both sequences the SIMUL and BAYLOC algorithms produce hypocenter locations of comparable accuracy, while location error estimates from SIMUL are generally less accurate than BAYLOC's. This result is a confirmation in a 3D velocity structure of a finding already reported by previous investigators who compared the performances of linear vs. non-linear location algorithms in 1D structures (Lomax et al., 1998; Lomax et al., 2000; Lippitsch et al., 2005) and further underlines the implications of the linearization process. Also, referring to the problem of detecting seismogenic faults from hypocenter trends delineated in poor network conditions, we introduced a procedure based on BAYLOC's location probability concept with the purpose of establishing when hypocenter trends really mark seismogenic structures and when they simply reflect ill-conditionning of the location process. This procedure (ISO-TEST) showed that while the NE-SW trend of the 2002 sequence can only in minor part be ascribed to ill-conditioning of the location process (what basically means that it effectively marks the orientation of the source), the NW-SE trend of the 1998 sequence is strongly contamined by the location process and source detection is therefore doubtful in this case. Although ISO-TEST is shown to be already capable to bring benefits to seismogenic fault detection in areas where the location problem ill-conditionned, improvements can be expected from wider testing of synthetic earthquake generators and deeper evaluation of misfits between synthetic and real location probability distributions in the space domain. Efforts are currently made in this connection. References Evans, J. R., Eberhart-Phillips, D. & Thurber, C. H., 1994. User's manual for simulps12 for imaging Vp and Vp/Vs: a derivative of the "Thurber" tomographic inversion simul3 for local earthquakes and explosions, U.S. Geol. Surv. Open-file Rept., 94-431. Lippitsch, R., White, R., & Soosalu, H. 2005. Precise hypocentre relocation of microearthquakes in a high- temperature geothermal field: the Torfajökull central volcano, Iceland, Geophysical Journal International 160 - 371-388. Lomax, A., Cattaneo, M., Bethoux, N., Deschamps, A., Courboulex, F., Deverchère, J., & Virieux, J., 1998. Comparison of linear and non-linear earthquake locations for the 1995 Ventimiglia sequence, Poster presentation at: European Geophysical Society, XXII General Assembly, http://alomax.free.fr/posters/vintimiglia. Lomax A., Virieux, J., Volant, P., & Berge-Thierry C., 2000. Probabilistic earthquake location in 3D and layered model, in Advances in Seismic Event Location, 101-134, Kluwer Academic Publishers, Netherlands. Presti, D., Troise, C. & De Natale G., 2004. Probabilistic location of seismic sequences in heterogeneous media, Bull. Seism. Soc. Am., 94, 6, 2239 2253.

Presti, D.; Orecchio, B.; Falcone, G.; Neri, G.

2006-12-01

402

Linear features determined from Landsat imagery in western Kansas  

USGS Publications Warehouse

A map (scale 1:500,000) shows the linear features determined from Landsat imagery in western Kansas. The linear features, sometimes called linear trends or lineaments, are not identified as to type or origin. Most probably represent fractures or fracture zones, which may affect the movement of water or other fluids through the rocks. The linear features are classified as to length--less than 30 miles and more than 30 miles. (USGS)

Cooley, M.E.

1984-01-01

403

How should trends in hydrological extremes be estimated?  

NASA Astrophysics Data System (ADS)

A comparison of six procedures for estimating the linear trend parameter ? in annual maximum 1 day river flows at five sites in southern Brazil showed marked differences between, on the one hand, estimates obtained by incorporating trend into the generalized extreme value (GEV) location parameter with all parameters estimated by maximum likelihood (ML) and on the other hand, estimates found by least squares, trend removal prior to fitting the GEV by ML, boot-strap sampling, and Theil-Sen estimation. ML estimates of trend were considerably smaller than those given by all other procedures. The same was true where trend had been incorporated into the Gumbel location parameter. Where 95% confidence intervals were calculated for the "true" trend ? by different procedures, some confidence intervals bracketed zero (indicating that the trend was not "significant" at the 5% level), but there was no consistency between results from different procedures; Theil-Sen confidence intervals always bracketed zero, confidence intervals given by detrending never did. It is concluded that not only do different estimation procedures give different measures of trend uncertainty, as reported elsewhere, but the estimated trends themselves may differ, and the paper suggests an explanation why this may occur. Some philosophical issues relating to estimation of trend in climatological and hydrological extremes are discussed, and it is concluded that selection of a method to estimate trend must depend on context.

Clarke, Robin T.

2013-10-01

404

Population status and trends of Southern Giant Petrels ( Macronectes giganteus ) breeding in North Patagonia, Argentina  

Microsoft Academic Search

The actual breeding population of the Southern Giant Petrel from the northern Patagonian colonies of Argentina on Isla Arce and Isla Gran Robredo was estimated to be 2,300 pairs. The available data sets are small, but showed a positive linear trend at Isla Gran Robredo over the last 14 years, but no trend was detected by a linear model at Isla

Flavio Quintana; Gabriel Punta; Sofía Copello; Pablo Yorio

2006-01-01

405

Trends in Education.  

ERIC Educational Resources Information Center

Presents several key findings from several recent National Center for Educational Statistics reports related national trends in education involving elementary school enrollment, poverty concentration, language minority students, student family characteristics, reading comprehension, academic achievement (math, science, geography), student access…

Snyder, Thomas D.; Freeman, Catherine E.

2003-01-01

406

Economic Trends: December 1999  

NSDL National Science Digital Library

Economic Trends, a monthly publication from FRB Cleveland, contains articles on labor markets, life expectancy and retirement, and personal, private, and government savings rates. The December 1999 issue reports on The Employment Cost Index, Bank Performance, and Interest Rates.

1999-01-01

407

?1 Trend Filtering  

E-print Network

changes in slope, of the estimated trend can be interpreted as abrupt ... especially popular in economics and related disciplines since its application to ...... Climate spectra and detecting climate change. Climate. Change, 21:275–287

2007-09-28

408

Trends in Exploitation  

E-print Network

Women cosponsored “Trends in Exploitation: La- bor TraffickingWOMEN csw update: november 2011 Department of Public Health, analyzed the health outcomes of traffickingWOMEN csw update: november 2011 CAST shelter. As a trafficking

Fardin, Halina

2011-01-01

409

Trends in Scholarly Communication  

E-print Network

Trends in Scholarly Communication University of Nebraska Scholarly Communication Symposium ? 2 May 2003 ? Lincoln, NE Richard Fyffe ? Assistant Dean for Scholarly Communication, University of Kansas Libraries ? or 50 Miles as the Crow Flies: A...

Fyffe, Richard

2003-05-01