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1

Propagation of linear surface air temperature trends into the terrestrial subsurface  

NASA Astrophysics Data System (ADS)

The thermal regime of the continental subsurface contains the record of the most recent changes in the energy balance at the ground surface. Borehole paleoclimatology methods can be applied to infer past ground surface temperature changes and to estimate the heat storage of the subsurface, thus contributing to ascertain the overall energy budget of the climate system. A crucial point is to understand the nature of the coupling between the atmosphere and the ground. Previous studies have examined air and ground temperature relationships working under the assumption that linear trends in surface air temperature should be equal to those measured at depth within the terrestrial subsurface. Here, a purely conductive model of heat conduction is used to show that surface trends are attenuated as a function of depth within conductive media, therefore invalidating the above assumption. The model is forced with synthetic linear surface temperature trends as the time varying upper boundary condition; synthetic trends are either noise free or include additions of Gaussian noise at the annual time scale. It is shown that over a 1000 year period, the trend is linearly damped with depth in both the noise-free and noise-added cases. However, when 100-year intervals are considered, the linear damping of the trend at depth is lost. An error estimate for the corresponding underground trend variation is determined by performing a Monte Carlo simulation. Using ECHO-G general circulation model output as a more realistic simulated data set, the damped trend behaviour as a function of depth is observed, although it is not linear. The use of air and soil temperature data collected over 99 years in Armagh, Ireland and 29 years in Fargo, North Dakota also do not show subsurface temperature trends that are equal to the surface trend. Over time scales smaller than 100 years and when noise is taken into account, damping of the temperature trend at depth is no longer observed due to the impact of annual variability on the trend estimates. It is therefore possible to observe the same trends at depth and at the surface, but such observations are not an indication that the ground and surface trends are directly coupled.

Lesperance, M. B.; Beltrami, H.; Smerdon, J. E.

2009-12-01

2

An assessment of three alternatives to linear trends for characterizing global atmospheric temperature changes  

NASA Astrophysics Data System (ADS)

Historical changes in global atmospheric temperature are typically estimated using simple linear trends. This paper considers three alternative simple statistical models, each involving breakpoints (abrupt changes): a flat steps model, in which all changes occur abruptly; a piecewise linear model; and a sloped steps model, incorporating both abrupt changes and slopes during the periods between breakpoints. First- and second-order autoregressive models are used in combination with each of the above. Goodness of fit of the models is evaluated using the Schwarz Bayesian Information Criterion. These models are applied to the instrumental record of global monthly temperature anomalies at the surface and to the radiosonde and satellite records for the troposphere and stratosphere. The alternative models often provide a better fit to the observations than the simple linear model. Typically the two top-performing models have very close values of the Schwarz Bayesian Information Criterion. Usually the two models have the same basic form and the same net temperature change but with a different choice of autoregressive model. However, in some cases the best fits are from two different basic models, yielding different net temperature changes and suggesting different interpretations of the nature of those changes. For the surface data during 1900-2002 the sloped steps and piecewise linear models offer the best fits. Results for tropospheric data suggest that it is reasonable to consider most of the warming during 1958-2001 to have occurred at the time of the abrupt climate regime shift in 1977. Two fundamentally different, but equally valid, descriptions of stratospheric cooling were found: gradual linear change versus more abrupt ratcheting down of temperature concentrated in postvolcanic periods (˜2 years after eruption). Because models incorporating abrupt changes can be as explanatory as simple linear trends, we suggest consideration of these alternatives in climate change detection and attribution studies.

Seidel, Dian J.; Lanzante, John R.

2004-07-01

3

Ozone and temperature trends  

NASA Technical Reports Server (NTRS)

An update of the extensive reviews of the state of knowledge of measured ozone trends published in the Report of the International Ozone Trends Panel is presented. The update contains a review of progress since these reports, including reviewing of the ozone records, in most cases through March 1991. Also included are some new, unpublished reanalyses of these records including a complete reevaluation of 29 stations located in the former Soviet Union. The major new advance in knowledge of the measured ozone trend is the existence of independently calibrated satellite data records from the Total Ozone Mapping Spectrometer (TOMS) and Stratospheric Aerosol and Gas Experiment (SAG) instruments. These confirm many of the findings, originally derived from the Dobson record, concerning northern mid-latitude changes in ozone. We now have results from several instruments, whereas the previously reported changes were dependent on the calibration of a single instrument. This update will compare the ozone records from many different instruments to determine whether or not they provide a consistent picture of the ozone change that has occurred in the atmosphere. The update also briefly considers the problem of stratospheric temperature change. As in previous reports, this problem received significantly less attention, and the report is not nearly as complete. This area needs more attention in the future.

Stolarski, Richard S.; Fioletov, Vitali; Bishop, Lane; Godin, Sophie; Bojkov, Rumen D.; Kirchhoff, Volker; Chanin, Marie-Lise; Zawodny, Joseph M.; Zerefos, Christos S.; Chu, William

1991-01-01

4

Linear trend analysis: a comparison of methods  

Microsoft Academic Search

In this paper, we present an overview of statistical approaches available for detecting and estimating linear trends in environmental data. We evaluate seven methods of trend detection and make recommendations based on a simulation study. We also illustrate the methods using real data.

Ann Hess; Hari Iyer; William Malm

2001-01-01

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

Extraordinary long-term trends in temperature extremes across Germany  

NASA Astrophysics Data System (ADS)

Properly evaluating temporal changes in the occurrence of extreme high or low temperatures is of key importance for assessing the potential local impacts of ongoing climatic changes and estimating possible future trends. Notably, the applicability of traditional extreme value statistics to non-stationary climate data is often restricted by the available amount of data. As a possible alternative, quantile regression techniques allow estimating temporal trends in arbitrary quantiles of the distribution of observed temperatures. Here, we report results on the long-term evolution of daily mean, maximum and minimum temperatures across Germany based on station data. The obtained trends in very high and low quantiles reveal an extraordinary increase of high temperature extremes since the 1950s, which significantly exceeds the mean warming. In order to assess the robustness of these results, we compare the trend values for linear and nonlinear (spline-based) quantile trends with those obtained from (linearly) time-dependent extreme value analysis. A detailed analysis of the spatial patterns of trend values suggests the specific importance of urban areas, but also local geographical factors for the emergence of extreme trends in the highest temperatures.

Donner, Reik; Wagner, Janna; Mettin, Viola

2014-05-01

7

Temperature and precipitation of Alaska: 50 year trend analysis  

Microsoft Academic Search

Summary  ?Temperature and precipitation records from 1949 to 1998 were examined for 25 stations throughout the State of Alaska. Mean,\\u000a maxima, and minima temperatures, diurnal temperature range, and total precipitation were analyzed for linear trends using\\u000a least squares regressions. Annual and seasonal mean temperature increases were found throughout the entire state, and the\\u000a majority were found to be statistically significant at

J. M. Stafford; G. Wendler; J. Curtis

2000-01-01

8

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

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

Linear Trends in Botanical Systematics and the Major Trends of Xylem Evolution  

E-print Network

Linear Trends in Botanical Systematics and the Major Trends of Xylem Evolution Mark E. Olson1,2 1 York Botanical Garden 2012 Abstract For nearly a century the so-called Major Trends of Xylem Evolution . Evolution . Great Chain of Being . Homoplasy. Systematics . Xylem Bot. Rev. DOI 10.1007/s12229

Olson, Mark

11

Global Trends of Lake Surface Temperatures Observed From Space  

NASA Astrophysics Data System (ADS)

The water temperature of lakes and other inland water bodies is a good indicator of climate variability. Unfortunately, the existing record of sufficiently long, homogeneous, and reliable in situ measurements is very sparse on a global scale and is nearly non-existent in many less developed parts of the world. Satellite-based thermal infrared (TIR) remote sensing is currently the only feasible method to provide a consistent and global overview of lake temperatures and provides a nearly 30-year record for determining trends. Here we present results from a trend analysis performed at large lakes worldwide using satellite-based TIR data from the series of Advanced Very High Resolution Radiometers (AVHRR) and the series of Along-Track Scanning Radiometers (ATSR) between 1985 and 2009. Time series of surface water temperature were extracted over 169 study sites worldwide and a linear regression model was fitted to the seasonal summertime means. A validation of the computed trends at the North American Great Lakes shows that the satellite-derived trends closely match corresponding trends obtained from in situ data measured at buoys in the lake. Subsequently, trends were computed for all study sites and the results indicate that overall the water bodies have warmed at an average rate of 0.045 ± 0.011 °C/yr (p < 0.001). No significant cooling trends were found. A map of the spatial distribution of the trends shows far greater warming in the mid- and high latitudes of the northern hemisphere than at low latitudes and the southern hemisphere. The strongest increasing trends were found over Northern Europe where rates as high as 0.10 ± 0.01 °C/yr were measured for the period 1985-2009. From there the rates decrease slightly towards southeastern Europe and towards Asia. Lakes in North America have been warming at average rates of around 0.05 °C/yr. At lower latitudes, most inland water bodies showed much slower trends or no significant change. A comparison with data from the GISTEMP surface air temperature analysis shows qualitatively that the spatial patterns found for the lake temperature trends agree reasonably well with those found for surface air temperature over the same period. Overall, our study demonstrates that the existing record of TIR satellite data offers the opportunity to estimate temperature trends of inland water bodies at a large number of sites worldwide and that many large lakes have been subject to significant warming since 1985.

Schneider, P.; Hook, S. J.

2012-04-01

12

What's Up With the Weather?: Temperature Trends  

NSDL National Science Digital Library

This classroom activity gives students an opportunity to use a statistical analysis technique, the moving average, to search for meaningful trends in regional raw temperature data. Students will first plot the Monthly Average Temperatures for Boston, Massachusetts. They then calculate and graph a 12-Month Moving Average, which allows them to do a continuous average of their data. Lastly, the students will analyze the graphs to find any overall trends and discuss their findings. The activity has a stated objective, a list of materials, procedure, activity answers, and links for more information.

13

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)

Cindy Starr

2003-10-23

14

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.

Cindy Starr

2004-12-13

15

Spring phenology trends in Alberta, Canada: links to ocean temperature  

NASA Astrophysics Data System (ADS)

Warmer winter and spring temperatures have been noted over the last century in Western Canada. Earlier spring plant development in recent decades has been reported for Europe, but not for North America. The first-bloom dates for Edmonton, Alberta, were extracted from four historical data sets, and a spring flowering index showed progressively earlier development. For Populus tremuloides, a linear trend shows a 26-day shift to earlier blooming over the last century. The spring flowering index correlates with the incidence of El Niño events and with Pacific sea-surface temperatures.

Beaubien, E. G.; Freeland, H. J.

16

Twentieth-century sea surface temperature trends  

SciTech Connect

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 to an exogenous heating of the tropical atmosphere. This pattern, however, is not reproduced by the complex ocean-atmosphere circulation models currently used to simulate the climatic response to increased greenhouse gases. Its presence is likely to lessen the mean 20th-century global temperature change in model simulations. 31 refs., 4 figs.

Cane, M.A.; Clement, A.C.; Kaplan, A. [Lamont-Doherty Earth Observatory, Palisades, NY (United States)] [and others] [Lamont-Doherty Earth Observatory, Palisades, NY (United States); and others

1997-02-14

17

Trends in Surface Temperature at High Latitudes  

NASA Technical Reports Server (NTRS)

The earliest signal of a climate change is expected to be found in the polar regions where warming is expected to be amplified on account of ice-albedo feedbacks associated with the high reflectivity of snow and ice. Because of general inaccessibility, there is a general paucity of in situ data and hence the need to use satellite data to observe the large-scale variability and trends in surface temperature in the region. Among the most important sensors for monitoring surface temperature has been the Advanced Very High Resolution Radiometer (AVHRR) which was first launched in 1978 and has provided continuous thermal infrared data since 1981. The top of the atmosphere data are converted to surface temperature data through various schemes that accounts for the unique atmospheric and surface conditions in the polar regions. Among the highest source of error in the data is cloud masking which is made more difficult in the polar region because of similar Signatures of clouds and snow lice covered areas. The availability of many more channels in the Moderate Resolution Imaging Spectroradiometer (MODIS) launched on board Terra satellite in December 1999 and on board Aqua in May 2002 (e.g., 36 visible and infrared channels compared to 5 for AVHRR) made it possible to minimize the error. Further capabilities were introduced with the Advanced Microwave Scanning Radiometer (AMSR) which has the appropriate frequency channels for the retrieval of sea surface temperature (SST). The results of analysis of the data show an amplified warming in the Arctic region, compared with global warming. The spatial distribution of warming is, however, not uniform and during the last 3 decades, positive temperature anomalies have been most pronounced in North America, Greenland and the Arctic basin. Some regions of the Arctic such as Siberia and the Bering Sea surprisingly show moderate cooling but this may be because these regions were anomalously warm in the 1980s when the satellite record started. Also, the SST in the Arctic basin is observed to be anomalously high in 2007 when the perennial ice cover declined dramatically to its lowest extent. In the Antarctic, surface temperature trends are much more moderate with the most positive trends occurring in the Antarctic Peninsula and parts of Western Antarctica while some cooling are observed in the Antarctic Plateau and the Ross Sea. The trends in SST in the region is similar to global averages but precipitation from more evaporation may have a key role in the spatial distribution of surface temperature in the ice covered region

Comiso, Josefino C.

2012-01-01

18

Piecewise linear fitting and trend changing points of climate parameters  

NASA Astrophysics Data System (ADS)

Finding an overall linear trend is a common method in scientific studies. It is almost a requirement when one intends to study variability. Nevertheless, when dealing with long climate temporal series, fitting a straight line only seldom has a relevant meaning. This paper proposes and describes a new methodology for finding overall trends, and, simultaneously, for computing a new set of climate parameters: the breakpoints between periods with significantly different trends. The proposed methodology uses a least-squares approach to compute the best continuous set of straight lines that fit a given time series, subject to a number of constraints on the minimum distance between breakpoints and on the minimum trend change at each breakpoint. The method is tested with three climate time series.

Tomé, A. R.; Miranda, P. M. A.

2004-01-01

19

Interdecadal trend turning of global terrestrial temperature and precipitation during 1951–2002  

Microsoft Academic Search

A grid-by-grid counting of interdecadal trend turning (ITT) of annual mean surface air temperature (SAT) and total precipitation at 67,359 terrestrial grids in the period 1951–2002 is presented. An analysis of the last ITTs of SAT and total precipitation in the period, in the context of both occurrence time and linear trends after the breakpoint, indicates that a warming trend

Xiaohui Shi; Xiangde Xu

2008-01-01

20

Spatial analysis of the temperature trends in Serbia during the period 1961-2010  

NASA Astrophysics Data System (ADS)

The spatial analysis of annual and seasonal temperature trends in Serbia during the period 1961-2010 was carried out using mean monthly data from 64 meteorological stations. Change year detection was achieved using cumulative sum charts. The magnitude of trends was derived from the slopes of linear trends using the least square method. The same formalism of least square method was used to assess the statistical significance of the determined trends. Maps of temperature trends were generated by applying a spatial regression method to visualize the detected tendencies. The obtained results indicate a negative temperature trend for the period before the change year except for winter and a more pronounced positive trend after the change year. Besides being more pronounced, the vast majority of trends after the change year were also clearly statistically significant. Our estimate of the average temperature trend over Serbia is in agreement with those obtained at the global and European scale. Calculated global autocorrelation statistics (Moran's I) indicate an apparent random spatial pattern of temperature trends across the Serbia for both periods before and after the change year.

Bajat, Branislav; Blagojevi?, Dragan; Kilibarda, Milan; Lukovi?, Jelena; Toši?, Ivana

2014-08-01

21

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

22

Trends in high temperature gas turbine materials  

NASA Technical Reports Server (NTRS)

High performance - high technology materials are among the technologies that are required to allow the fruition of such improvements. Materials trends in hot section components are reviewed, and materials for future use are identified. For combustors, airfoils, and disks, a common trend of using multiple material construction to permit advances in technology is identified.

Grisaffe, S. J.; Dreshfield, R. L.

1981-01-01

23

Trends in seasonal temperatures over the Indian region  

NASA Astrophysics Data System (ADS)

An investigation has been carried out to identify the trends in maximum, minimum and mean temperatures and temperature range over the Indian land mass during the winter (January, and February), pre-monsoon (March-May), southwest monsoon (June-September) and post-monsoon (October-December) seasons by using high resolution daily gridded data set prepared by India Meteorological Department for the period of 1969-2005. It has been observed that the maximum temperatures over the west coast of India show rising trend in winter, southwest monsoon and post-monsoon seasons but the maximum temperatures do not show any significant trend over the other parts of the country. Minimum temperatures show increasing trend over the North Indian states in all seasons and they show an increasing trend over the west coast of India in winter and southwest monsoon seasons. Mean temperature shows an increasing trend over the west coast of India during winter and southwest monsoon seasons. Decreasing trend is observed in the temperature range over North India in all seasons due to increasing trend in minimum temperature.

Wagholikar, Nilesh K.; Sinha Ray, K. C.; Sen, P. N.; Kumar, P. Pradeep

2014-06-01

24

Northern hemisphere temperature trends: A possible greenhouse gas effect  

Microsoft Academic Search

Radiosonde temperature data from 147 stations in the Northern Hemisphere for the period 1964-85 have been used to investigate recent temperature trends in the troposphere and lower stratosphere. Experiments with atmospheric general circulation models indicate that increased concentrations of greenhouse gases in the atmosphere will lead to reduced temperatures in the stratosphere as well as increased temperatures in the troposphere.

David J. Karoly

1989-01-01

25

SUMMER TEMPERATURE TRENDS IN A MEDITERRANEAN AREA (VALENCIA REGION)  

Microsoft Academic Search

Within the area of climate change, summer temperatures are of special interest because of the economic, social and environmental consequences that can derive from their hypothetical increase. A number of recent studies have shown a worldwide trend towards increasing summer temperatures. In this work, we analyse summer temperatures (July and August) in the Valencia region of Spain from 1958 to

J. J. MIR; M. J. ESTRELA; Charles R. Darwin

26

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

27

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

28

Seasonality in future tropical lower stratospheric temperature trends  

NASA Astrophysics Data System (ADS)

The seasonality of the 21st century trends in tropical lower stratospheric temperature (LST) is examined in simulations by a group of comprehensive chemistry-climate models. In contrast to the past LST trends, there is robust seasonal dependence among ensembles of the same model. Furthermore, most models show strongest cooling around July-September and minimal cooling in February-March, which results in a weakening of the seasonality in tropical LST. Sensitivity simulations with isolated forcing reveal that greenhouse gas increases dominate the future tropical LST trend. This seasonally varying LST trend is linked to changes in the Brewer-Dobson circulation (BDC). The BDC can influence the LST through direct dynamical heating/cooling and indirect radiative effects primarily from ozone changes due to vertical transport. The latter is found to be the main cause for the seasonality of the 21st century LST trend, while it is difficult to separate them in the past.

Wang, Lei; Waugh, Darryn W.

2015-02-01

29

Abundances of Stars with Planets: Trends with Condensation Temperature  

NASA Astrophysics Data System (ADS)

Precise abundances of 18 elements have been derived for 10 stars known to host giant planets from high signal-to-noise ratio, high-resolution echelle spectroscopy. Internal uncertainties in the derived abundances are typically <~ 0.05 dex. The stars in our sample have all been previously shown to have abundances that correlate with the condensation temperature (T c) of the elements in the sense of increasing abundances with increasing T c; these trends have been interpreted as evidence that the stars may have accreted H-depleted planetary material. Our newly derived abundances also correlate positively with T c, although slopes of linear least-square fits to the [m/H]-T c relations for all but two stars are smaller here than in previous studies. When considering the refractory elements (T c >900 K) only, which may be more sensitive to planet formation processes, the sample can be separated into a group with positive slopes (four stars) and a group with flat or negative slopes (six stars). The four stars with positive slopes have very close-in giant planets (three at 0.05 AU) and slopes that fall above the general Galactic chemical evolution trend. We suggest that these stars have accreted refractory-rich planet material but not to the extent that would increase significantly the overall stellar metallicity. The flat or negative slopes of the remaining six stars are consistent with recent suggestions of a planet formation signature, although we show that the trends may be the result of Galactic chemical evolution. Based on observations with the High Resolution Spectrograph on the Hobby-Eberly Telescope, which is operated by McDonald Observatory on behalf of the University of Texas at Austin, Pennsylvania State University, Standford University, the Ludwig-Maximilians-Universität München, and the Georg-August-Universität, Göttingen. Based on observations made with the FEROS instrument on the MPG/ESO 2.2 m telescope at La Silla (Chile), under the agreement ESO-Observatório Nacional/MCT.

Schuler, Simon C.; Flateau, Davin; Cunha, Katia; King, Jeremy R.; Ghezzi, Luan; Smith, Verne V.

2011-05-01

30

Temperature and Malaria Trends in Highland East Africa  

PubMed Central

There has been considerable debate on the existence of trends in climate in the highlands of East Africa and hypotheses about their potential effect on the trends in malaria in the region. We apply a new robust trend test to mean temperature time series data from three editions of the University of East Anglia's Climatic Research Unit database (CRU TS) for several relevant locations. We find significant trends in the data extracted from newer editions of the database but not in the older version for periods ending in 1996. The trends in the newer data are even more significant when post-1996 data are added to the samples. We also test for trends in the data from the Kericho meteorological station prepared by Omumbo et al. We find no significant trend in the 1979-1995 period but a highly significant trend in the full 1979-2009 sample. However, although the malaria cases observed at Kericho, Kenya rose during a period of resurgent epidemics (1994-2002) they have since returned to a low level. A large assembly of parasite rate surveys from the region, stratified by altitude, show that this decrease in malaria prevalence is not limited to Kericho. PMID:21935416

Stern, David I.; Gething, Peter W.; Kabaria, Caroline W.; Temperley, William H.; Noor, Abdisalan M.; Okiro, Emelda A.; Shanks, G. Dennis; Snow, Robert W.; Hay, Simon I.

2011-01-01

31

Spatial analysis of mean temperature trends in Spain over the period 1961-2006  

NASA Astrophysics Data System (ADS)

The spatial distribution of recent mean temperature trends over Spain during the period 1961-2006 at monthly, seasonal and annual time scale is carried out in this study by applying various statistical tools to data from 473 weather stations. The magnitude of trends was derived from the slopes of the linear trends using ordinary least-square fitting. The non-parametric Mann-Kendall test was used to determine the statistical significance of trends. Maps of surface temperature trends were generated by applying a geostatistical interpolation technique to visualize the detected tendencies. This study reveals that temperature has generally increased during all months and seasons of the year over the last four decades. More than 60% of whole Spain has evidenced significant positive trends in March, June, August, spring and summer. This percentage diminishes around 40% in April, May and December. Annual temperature has significantly risen in 100% of Spain of around 0.1-0.2 °C/decade according to the Fourth Assessment Report of the IPCC.

del Río, S.; Herrero, L.; Pinto-Gomes, C.; Penas, A.

2011-07-01

32

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

33

Maximum And Minimum Temperature Trends In Mexico For The Last 31 Years  

NASA Astrophysics Data System (ADS)

Based on high-resolution (1') daily maps of the maximum and minimum temperatures in Mexico, an analysis of the last 31-year trends is performed. The maps were generated using all the available information from more than 5,000 stations of the Mexican Weather Service (Servicio Meteorológico Nacional, SMN) for the period 1979-2009, along with data from the North American Regional Reanalysis (NARR). The data processing procedure includes a quality control step, in order to eliminate erroneous daily data, and make use of a high-resolution digital elevation model (from GEBCO), the relationship between air temperature and elevation by means of the average environmental lapse rate, and interpolation algorithms (linear and inverse-distance weighting). Based on the monthly gridded maps for the mentioned period, the maximum and minimum temperature trends calculated by least-squares linear regression and their statistical significance are obtained and discussed.

Romero-Centeno, R.; Zavala-Hidalgo, J.; Allende Arandia, M. E.; Carrasco-Mijarez, N.; Calderon-Bustamante, O.

2013-05-01

34

Temperature trends during the Present and Last Interglacial periods - a multi-model-data comparison  

NASA Astrophysics Data System (ADS)

Though primarily driven by insolation changes associated with well-known variations in Earth's astronomical parameters, the response of the climate system during interglacials includes a diversity of feedbacks involving the atmosphere, ocean, sea ice, vegetation and land ice. A thorough multi-model-data comparison is essential to assess the ability of climate models to resolve interglacial temperature trends and to help in understanding the recorded climatic signal and the underlying climate dynamics. We present the first multi-model-data comparison of transient millennial-scale temperature changes through two intervals of the Present Interglacial (PIG; 8-1.2 ka) and the Last Interglacial (LIG; 123-116.2 ka) periods. We include temperature trends simulated by 9 different climate models, alkenone-based temperature reconstructions from 117 globally distributed locations (about 45% of them within the LIG) and 12 ice-core-based temperature trends from Greenland and Antarctica (50% of them within the LIG). The definitions of these specific interglacial intervals enable a consistent inter-comparison of the two intervals because both are characterised by minor changes in atmospheric greenhouse gas concentrations and more importantly by insolation trends that show clear similarities. Our analysis shows that in general the reconstructed PIG and LIG Northern Hemisphere mid-to-high latitude cooling compares well with multi-model, mean-temperature trends for the warmest months and that these cooling trends reflect a linear response to the warmest-month insolation decrease over the interglacial intervals. The most notable exception is the strong LIG cooling trend reconstructed from Greenland ice cores that is not simulated by any of the models. A striking model-data mismatch is found for both the PIG and the LIG over large parts of the mid-to-high latitudes of the Southern Hemisphere where the data depicts negative temperature trends that are not in agreement with near zero trends in the simulations. In this area, the positive local summer insolation trend is counteracted in climate models by an enhancement of the Southern Ocean summer sea-ice cover and/or an increase in Southern Ocean upwelling. If the general picture emerging from reconstructions is realistic, then the model-data mismatch in mid and high Southern Hemisphere latitudes implies that none of the models is able to resolve the correct balance of these feedbacks, or, alternatively, that interglacial Southern Hemisphere temperature trends are driven by mechanisms which are not included in the transient simulations, such as changes in the Antarctic ice sheet or meltwater-induced changes in the overturning circulation.

Bakker, P.; Masson-Delmotte, V.; Martrat, B.; Charbit, S.; Renssen, H.; Gröger, M.; Krebs-Kanzow, U.; Lohmann, G.; Lunt, D. J.; Pfeiffer, M.; Phipps, S. J.; Prange, M.; Ritz, S. P.; Schulz, M.; Stenni, B.; Stone, E. J.; Varma, V.

2014-09-01

35

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)

Cindy Starr

2003-10-23

36

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)

Cindy Starr

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)

Cindy Starr

2003-10-23

38

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)

Cindy Starr

2003-10-23

39

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)

Cindy Starr

2003-10-23

40

Tropospheric Temperature Trends on Decadal Scale from Measurements on Aqua  

NASA Astrophysics Data System (ADS)

We use the Atmospheric Infrared Sounder (AIRS) and Advance Microwave Sounding Unit (AMSU) measurements carried out on Aqua satellite in 2002-2011 to infer mid-tropospheric temperature variability on decadal time scale. Since AMSU soundings are independent on the CO2 its measurements track natural climate variability. However the AIRS sounding channels at AMSU comparable levels are sensitive to the changes in CO2. The difference between AIRS and AMSU removes the natural variability and reveals the variability of CO2. The trend in AIRS data is determined accurately. Thus its surface channels drift less than 5 mK/yr based on the validation with sea surface temperatures measured by ocean buys. The AMSU weighing functions do not localized near the sea surface. Comparison of trends in the difference record with the CO2 trends found from the ground stations and with the trends determined directly from the mid-tropospheric global CO2 retrieved from the same satellite data allows us to evaluate the long-term stability of the widely used AMSU measurements, and, once the stability is established, to use the AMSU-AIRS difference records for diagnostic of the atmospheric CO2 data. The analysis of AMSU-AIRS differences reveals different trends over oceans, over localized land regions, and zonally averaged regions, which we interpret as related to CO2 transport effects. This work was supported by the Jet Propulsion Laboratory of the California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

Ruzmaikin, A.; Aumann, H. H.

2011-12-01

41

Analysis of the impacts of station exposure on the U.S. Historical Climatology Network temperatures and temperature trends  

Microsoft Academic Search

Temperature trend estimates vary according to site classificationPoorly sited stations are warmer compared to interpolated NARR temperaturesThe diurnal temperature range in the lower 48 states has no century-scale trend

Souleymane Fall; Anthony Watts; John Nielsen-Gammon; Evan Jones; Dev Niyogi; John R. Christy; Roger A. Pielke

2011-01-01

42

Trends in Snow Cover and Temperature in Alaska  

NSDL National Science Digital Library

This lesson is designed to help students gain knowledge in using the MY NASA DATA Live Access Server (LAS) to specify and download a microset of data, and then to use the data to compare NASA satellite data observations with surface measurements of snow cover and temperature. Students will obtain snow cover and surface temperature data for a locale in Alaska, plot the data, and then investigate seasonal trends in snow cover, and the relationship between snow cover and surface temperature at that locale. The lesson provides detailed procedure, related links and sample graphs, follow-up questions and extensions, and Teacher Notes.

2010-03-14

43

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

44

Accessing Recent Trend of Land Surface Temperature from Satellite Observations  

NASA Astrophysics Data System (ADS)

Land surface temperature (LST) is an important element to measure the state of the terrestrial ecosystems and to study the surface energy budgets. In support of the land cover/land use change related international program MAIRS (Monsoon Asia Integrated Regional Study), we have collected the global monthly LST measured by MODIS since the beginning of the missions. The MODIS LST time series have ~11 years of data from Terra since 2000 and ~9 years of data from Aqua since 2002, which makes possible to study the recent climate, such as trend and variability. In this study, monthly climatology from two satellite platforms are calculated and compared. The spatial patterns of LST trends are accessed, focusing on the Asian Monsoon region. Furthermore, the MODIS LST trends are compared with the skin temperature trend from the NASA's atmospheric assimilation model, MERRA (MODERN ERA RETROSPECTIVE-ANALYSIS FOR RESEARCH AND APPLICATIONS), which has longer data record since 1979. The calculated climatology and anomaly of MODIS LST will be integrated into the online visualization system, Giovanni, at NASA GES DISC for easy access and use by scientists and general public.

Shen, S.; Leptoukh, G. G.; Romanov, P.

2011-12-01

45

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

46

Regional tropical temperature trends from radiosondes, reanalyses, and satellite observations  

NASA Astrophysics Data System (ADS)

We compare seasonal 20th century atmospheric temperature trends in the Tropics (30°S-30°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 reveal an amplified upper tropospheric warming for all longest periods of dataset overlap (1901-99, 1901-57, 1948-99, 1957-99). ERA-40 and NNR show a second warming maximum in the lower troposphere which is missing in 20CR. The agreement of the vertical structure and temporal behaviour of regional, bidecadal trends in the long reanalyses for 4 regions in the Tropics with CHUAN is generally best for ERA-40, followed by a less good agreement with trends from NNR and 20CR. The performance of ERA-40 is best in the Americas sector, and less so in the Asian and Pacific sectors. The agreement of NNR with CHUAN is significantly worse than that of ERA-40 for all tropical regions, especially with respect to the vertical structure of the trends. The 20CR temporal behaviour and vertical structure of the tropical trends is often different from CHUAN, ERA-40 and NNR, especially around the tropopause, and in all sectors. For the more recent but shorter reanalyses, ERA-Interim is generally closer to ERA-40 than CFSR and MERRA. For the period of overlap (1951-99) CHUAN itself agrees reasonably well with HadAT, IUK, RAOBCORE/RICH and RATPAC on the general picture. However, some disagreement on the trend sign can be seen a) for the American sector during 1961-80 with RAOBCORE/RICH and RATPAC and during 1971-90 with RAOBCORE/RICH, b) for the Asian sector during 1961-80 with RAOBCORE/RICH.

Stickler, Alexander; Brönnimann, Stefan

2013-04-01

47

Long term water temperature trends in Austrian rivers  

Microsoft Academic Search

Monthly mean data collected for a 90 year period (1901-1990) have been used to study long term water temperature trends at 10 river sites in Austria. Significant increases in monthly mean values were evident over the study period for seven river stations, but the magnitude of the rise varied from 0.47 to 1.26°C and its pattern was not uniform between

B. W. WEBB

1995-01-01

48

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

49

Accessing Recent Trend of Land Surface Temperature from Satellite Observations  

NASA Technical Reports Server (NTRS)

Land surface temperature (Ts) is an important element to measure the state of terrestrial ecosystems and to study surface energy budgets. In support of the land cover/land use change-related international program MAIRS (Monsoon Asia Integrated Regional Study), we have collected global monthly Ts measured by MODIS since the beginning of the missions. The MODIS Ts time series have approximately 11 years of data from Terra since 2000 and approximately 9 years of data from Aqua since 2002, which makes possible to study the recent climate, such as trend. In this study, monthly climatology from two platforms are calculated and compared with that from AIRS. The spatial patterns of Ts trends are accessed, focusing on the Eurasia region. Furthermore, MODIS Ts trends are compared with those from AIRS and NASA's atmospheric assimilation model, MERRA (Modern Era Retrospective-analysis for Research and Applications). The preliminary results indicate that the recent 8-year Ts trend shows an oscillation-type spatial variation over Eurasia. The pattern is consistent for data from MODIS, AIRS, and MERRA, with the positive center over Eastern Europe, and the negative center over Central Siberia. The calculated climatology and anomaly of MODIS Ts will be integrated into the online visualization system, Giovanni, at NASA GES DISC for easy use by scientists and general public.

Shen, Suhung; Leptoukh, Gregory G.; Romanov, Peter

2011-01-01

50

Trends in surface air temperature and temperature extremes in the Great Basin during 1901-2010  

NASA Astrophysics Data System (ADS)

Guoping Tang and John A. Arnone III Division of Earth and Ecosystem Sciences, Desert Research Institute, Reno, Nevada 89512, USA Abstract: We analyzed natural 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, increase in daily minimum temperature and decrease in DTR occurred in all seasons but more significantly in summer. In contrast, daily maximum temperature showed no significant trend in any season. Increases in daily minimum temperature resulted in a decrease in the number of frost days (0.14±0.05 day yr-1) and cool nights (0.13±0.04 night yr-1) during each year from 1901 to 2010, while the number of warm nights increased significantly (0.17±0.03 night yr-1). Surprisingly, the number of warm and cool days and the length of the annual growing season showed no significant trend during the study period. None of these temporal patterns differed by elevation of the station. Thus, the results of this study suggest that continuation of these trends would lead to markedly warmer conditions in upcoming decades that may be drier than in past decades if precipitation does not increase.t;

Tang, G.; Arnone, J. A., III

2012-12-01

51

Apply a hydrological model to estimate local temperature trends  

NASA Astrophysics Data System (ADS)

Continuous times series {f(x)} such as a depth of water is written f(x) = T(x)+P(x)+S(x)+C(x) in hydrological science where T(x),P(x),S(x) and C(x) are called the trend, periodic, stochastic and catastrophic components respectively. We simplify this model and apply it to the local temperature data such as given E. Halley (1693), the UK (1853-2010), Germany (1880-2010), Japan (1876-2010). We also apply the model to CO2 data. The model coefficients are evaluated by a symbolic computation by using a standard personal computer. The accuracy of obtained nonlinear curve is evaluated by the arithmetic mean of relative errors between the data and estimations. E. Halley estimated the temperature of Gresham College from 11/1692 to 11/1693. The simplified model shows that the temperature at the time rather cold compared with the recent of London. The UK and Germany data sets show that the maximum and minimum temperatures increased slowly from the 1890s to 1940s, increased rapidly from the 1940s to 1980s and have been decreasing since the 1980s with the exception of a few local stations. The trend of Japan is similar to these results.

Igarashi, Masao; Shinozawa, Tatsuya

2014-03-01

52

A Test of Model Validation from Observed Temperature Trends  

NASA Astrophysics Data System (ADS)

How much of current warming is due to natural causes and how much is manmade? This requires a comparison of the patterns of observed warming with the best available models that incorporate both anthropogenic (greenhouse gases and aerosols) as well as natural climate forcings (solar and volcanic). Fortunately, we have the just published U.S.-Climate Change Science Program (CCSP) report (www.climatescience.gov/Library/sap/sap1-1/finalreport/default.htm), based on best current information. As seen in Fig. 1.3F of the report, modeled surface temperature trends change little with latitude, except for a stronger warming in the Arctic. The observations, however, show a strong surface warming in the northern hemisphere but not in the southern hemisphere (see Fig. 3.5C and 3.6D). The Antarctic is found to be cooling and Arctic temperatures, while currently rising, were higher in the 1930s than today. Although the Executive Summary of the CCSP report claims "clear evidence" for anthropogenic warming, based on comparing tropospheric and surface temperature trends, the report itself does not confirm this. Greenhouse models indicate that the tropics should provide the most sensitive location for their validation; trends there should increase by 200-300 percent with altitude, peaking at around 10 kilometers. The observations, however, show the opposite: flat or even decreasing tropospheric trend values (see Fig. 3.7 and also Fig. 5.7E). This disparity is demonstrated most strikingly in Fig. 5.4G, which shows the difference between surface and troposphere trends for a collection of models (displayed as a histogram) and for balloon and satellite data. [The disparities are less apparent in the Summary, which displays model results in terms of "range" rather than as histograms.] There may be several possible reasons for the disparity: Instrumental and other effects that exaggerate or otherwise distort observed temperature trends. Or, more likely: Shortcomings in models that result in much reduced values of climate sensitivity; for example, the neglect of important negative feedbacks. Allowing for uncertainties in the data and for imperfect models, there is only one valid conclusion from the failure of greenhouse models to explain the observations: The human contribution to global warming is still quite small, so that natural climate factors are dominant. This may also explain why the climate was cooling from 1940 to 1975 -- even as greenhouse-gas levels increased rapidly. An overall test for climate prediction may soon be possible by measuring the ongoing rise in sea level. According to my estimates, sea level should rise by 1.5 to 2.0 cm per decade (about the same rate as in past millennia); the U.N.-IPCC (4th Assessment Report) predicts 1.4 to 4.3 cm per decade. In the New York Review of Books (July 13, 2006), however, James Hansen suggests 20 feet or more per century -- equivalent to about 60 cm or more per decade.

Singer, S. F.

2006-12-01

53

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

54

Trends in rainy season characteristics and temperature extremes over Mexico  

NASA Astrophysics Data System (ADS)

There are significant uncertainties associated with the direction of change in climate patterns over Mexico. Many studies suggest that with global warming the country will experience impacts similar to those suffered during El Niño events, since a similar shift may occur in circulation regimes related to the North American Monsoon and also to sub-regional patterns such as the mid-summer drought. It is expected that the anomalously drier conditions experienced during El Niño events become a norm in the future. Also, in a scenario of higher mean temperatures, the occurrence of extreme temperature events becomes more likely. Heat waves can be devastating by themselves, but if they strike in the middle of a drought period, the effects of both are enhanced. Mexico is particularly vulnerable to climate variability, for its economy and population welfare are highly dependent on agriculture. The onset of the rainy season in spring and the occurrence of frost in fall are natural delimiters to the length of growing season. Intense precipitation mostly results in lixiviation of soil nutrients and high erosion rates, while moisture deficits and extremely high temperatures during crop flowering period can be detrimental to maize kernel development. In this study we will investigate the variability and trends of a set of indices that characterize the rainy season and the occurrence of extreme temperature events (Table 1). We will use daily precipitation (PPT) and maximum (Tmax) and minimum (Tmin) temperature fields from the North American Regional Reanalysis (NARR), in a sub-domain limited to Mexico, for the period 1979-2008. Daily Tmax and Tmin will be derived from 3-hourly outputs of air temperature at 2 m. All indices are seasonal and will be computed per grid point. However, the visualization of the temporal variability of these indices on a horizontal plane can be challenging. A regionalization procedure will therefore be tested. Regions delimited by coherent precipitation patterns can be identified through principal component analysis and are useful for climate variability studies. Daily PPT, Tmax and Tmin will be spatially averaged within each of the resulting regions, and the indices will be calculated with the regional time series. The results of this study are expected to depict a possible drying trend, eventual shifts in the onset and magnitude of the rainy season and the supposed increase in extreme temperature events.Table 1: Definitions of the indices for precipitation characteristics and temperature extremes *where A is the annual curve of daily anomalous accumulation of precipitation

Dewes, C. F.; Gautier, C.; Jones, C.; Eakin, H.; Carvalho, L. V.

2009-12-01

55

Analysis of the impacts of station exposure on the U.S. Historical Climatology Network temperatures and temperature trends  

E-print Network

Analysis of the impacts of station exposure on the U.S. Historical Climatology Network temperatures and temperature trends Souleymane Fall,1 Anthony Watts,2 John NielsenGammon,3 Evan Jones,2 Dev Niyogi,4 John R and temperature trends at national and regional scales and on differences between USHCN temperatures and North

Niyogi, Dev

56

Linear trends in cloud top height from passive observations in the oxygen A-band  

NASA Astrophysics Data System (ADS)

Measurements by the hyperspectral spectrometers GOME, SCIAMACHY and GOME-2 are used to determine the rate of linear change (and trends) in cloud top height (CTH) in the period between June 1996 and May 2012. The retrievals are obtained from Top-Of-Atmosphere (TOA) backscattered solar light in the oxygen A-band using the Semi-Analytical CloUd Retrieval Algorithm SACURA. The physical framework relies on the asymptotic equations of radiative transfer, valid for optically thick clouds. Using linear least-squares techniques, a global trend of -1.78 ± 2.14 m yr-1 in deseasonalized CTH has been found, in the latitude belt within ±60°, with diverging tendencies over land (+0.27 ± 3.2 m yr-1) and ocean (-2.51 ± 2.8 m yr-1). The El Niño-Southern Oscillation (ENSO), strongly coupled to CTH, forces clouds to lower altitudes. The global ENSO-corrected trend in CTH amounts to -0.49 ± 2.22 m yr-1. At a global scale, no explicit regional pattern of statistically significant trends (at 95% confidence level, estimated with bootstrap technique) have been found, which would be representative of typical natural synoptical features. One exception is North Africa, which exhibits the strongest upward trend in CTH sustained by an increasing trend in water vapour.

Lelli, L.; Kokhanovsky, A. A.; Rozanov, V. V.; Vountas, M.; Burrows, J. P.

2014-06-01

57

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

58

Inferring shark population trends from generalized linear mixed models of pelagic longline catch and effort data  

Microsoft Academic Search

We estimate recent (1992–2005) trends in relative abundance for Northwest Atlantic oceanic and large coastal sharks, using generalized linear mixed models to standardize catch rates of eight species groups as recorded by U.S. pelagic longline fishery observers. Models suggest precipitous (76%) declines in hammerhead (Sphyrna species) and large coastal (dusky, night, and silky shark, genus Carcharhinus) species, and moderate declines

Julia K. Baum; Wade Blanchard

2010-01-01

59

Statistical analysis of stratospheric temperature and ozone profile data for trends and model comparison  

NASA Technical Reports Server (NTRS)

Work performed during the project period July 1, 1990 to June 30, 1992 on the statistical analysis of stratospheric temperature data, rawinsonde temperature data, and ozone profile data for the detection of trends is described. Our principal topics of research are trend analysis of NOAA stratospheric temperature data over the period 1978-1989; trend analysis of rawinsonde temperature data for the period 1964-1988; trend analysis of Umkehr ozone profile data for the period 1977-1991; and comparison of observed ozone and temperature trends in the lower stratosphere. Analysis of NOAA stratospheric temperature data indicates the existence of large negative trends at 0.4 mb level, with magnitudes increasing with latitudes away from the equator. Trend analysis of rawinsonde temperature data over 184 stations shows significant positive trends about 0.2 C per decade at surface to 500 mb range, decreasing to negative trends about -0.3 C at 100 to 50 mb range, and increasing slightly at 30 mb level. There is little evidence of seasonal variation in trends. Analysis of Umkehr ozone data for 12 northern hemispheric stations shows significant negative trends about -.5 percent per year in Umkehr layers 7-9 and layer 3, but somewhat less negative trends in layers 4-6. There is no pronounced seasonal variation in trends, especially in layers 4-9. A comparison was made of empirical temperature trends from rawinsonde data in the lower stratosphere with temperature changes determined from a one-dimensional radiative transfer calculation that prescribed a given ozone change over the altitude region, surface to 50 km, obtained from trend analysis of ozonsonde and Umkehr profile data. The empirical and calculated temperature trends are found in substantive agreement in profile shape and magnitude.

Tiao, G. C.

1992-01-01

60

Trends and variability in East African rainfall and temperature observations  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

61

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

62

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

63

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

64

Linear analysis of surface temperature dynamics and climate sensitivity  

E-print Network

LINEAR ANALYSIS OF SURFACE TEMPERATURE DYNAMICS AND CLIMATE SENSITIVITY A Dissertation by WEI WU Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree... of DOCTOR OF PHILOSOPHY December 2005 Major Subject: Oceanography LINEAR ANALYSIS OF SURFACE TEMPERATURE DYNAMICS AND CLIMATE SENSITIVITY A Dissertation by WEI WU Submitted to the Office of Graduate...

Wu, Wei

2007-04-25

65

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

E-print Network

Institute of Ecosystem Studies 1 ANALYSIS OF A WARMING TREND IN WATER TEMPERATURE IN THE HUDSON occurred in the last 14 years. A seasonal analysis of trends indicated significant warming for the months are subject to warming due to global climate change but few studies to date have considered trends or rates

Lovett, Gary M.

66

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

67

Long-term trends in shortgrass steppe vegetation during a 21-year period of increasing temperatures  

SciTech Connect

Long-term weather records from the Central Plains Experimental Range revealed a general warming trend in average annual temperatures from 1971 through 1991. This was largely the result of a significant increase in mean annual minimum temperature (T{sub min}). Permanently marked vegetation quadrants were monitored for much of this same period. We constructed linear correlational models to assess relationships of annual and seasonal temperature and precipitation with plant densities and aboveground net primary productivity (ANPP) within a grazing exclosure. Response variables correlated with T{sub min} included: (i) tiller densities of the dominant grass, Bouteloua gracilis, and other warm season grasses, (ii) forb densities and ANPP, and (iii) total ANPP. Responses correlated with T{sub max} included: (i) total basal cover and (ii) densities and ANPP of several species. Plant species diversity was correlated with spring precipitation. Some species responded to the interactive effects of spring temperatures and precipitation. This investigation suggests that shortgrass steppe vegetation may be sensitive to climate change and supports predictions that asymmetric changes in diurnal temperatures may be an important component of climate change.

Alward, R.D.; Milchunas, D.G.; Detling, J.K. [Colorado State Univ., Fort Collins, CO (United States)

1995-06-01

68

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

69

Recalibration and merging of SSU observations for stratospheric temperature trend studies  

NASA Astrophysics Data System (ADS)

Long-term observations from the Stratospheric Sounding Unit (SSU) during 1979-2006 onboard NOAA historical polar orbiting satellites were recalibrated for climate change investigation. A two-point linear calibration equation, with cold space and an internal blackbody warm target as end-point references, was used to transfer SSU raw counts data into radiances. The warm target temperature was represented by measurements from the space side thermistor on the blackbody, and the cold space radiance was assumed to be zero. Space view corrections due to an electrical interference were applied. Intersatellite calibration was conducted simultaneously by applying calibration offsets determined from residual intersatellite biases. The recalibration reached an accuracy of 0.1-0.2 K for global means and thus is expected to improve the consistency in stratospheric temperature time series in climate reanalyses. The recalibrated SSU radiances were further adjusted to develop Version 2 of the NOAA stratospheric temperature time series. The effects being adjusted included those from changes in instrument cell pressure and atmospheric carbon dioxide concentration, viewing angle differences, and semidiurnal tides due to orbital drift. Intersatellite biases were carefully removed to ensure smooth transitions between satellite pairs. Differences from Version 1 included improved radiance calibration, improved adjusting schemes for diurnal drift and intersatellite biases, removal of time-varying cell pressure adjustment for NOAA-9 channel 1, and excluding NOAA-7 channel 2 in the time series. In addition to the final merged data set, intermediate synthetic time series corresponding to different adjustments were also created to quantify their impact on the final trend as well as its reliability and uncertainty. Excellent matching between satellite pairs, especially the 7 year overlaps between NOAA-11 and NOAA-14 during 1997-2004, in intermediate as well as the final time series provided strong evidence on the validity of adjustments and thus confidence on the resulting trends. The Version 2 global mean trends for 1979-2006 were -0.69 ± 0.18, -0.77 ± 0.15, and -0.85 ± 0.15 K/decade for SSU channels 1, 2, and 3, representing temperatures of middle stratosphere, upper stratosphere, and stratosphere-mesosphere, respectively. Among these, cooling of channel 2 was stronger and channel 3 weaker than those in UK Met Office (UKMO) data by about 1 K during the entire SSU period from 1979 to 2006. Finally, the average of the channel 1 and channel 3 anomalies in Version 2 was close to channel 2 anomalies to within 0.2 K for the entire 1979-2006 period with identical trends. This feature was found consistent with chemistry-climate model simulations.

Zou, Cheng-Zhi; Qian, Haifeng; Wang, Wenhui; Wang, Likun; Long, Craig

2014-12-01

70

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

71

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

2015-02-01

72

Trends of seasonal maximum and minimum temperatures and precipitation in Southern Brazil for the 1913-2006 period  

NASA Astrophysics Data System (ADS)

Long-term variations of monthly average maximum and minimum temperature (TMAX and TMIN) and precipitation records in southern Brazil are investigated for the 1913-2006 period. These variations are carefully analyzed for seasonal and annual indices, taken as regional averages. For this purpose, the serial correlation and trend of the indices are investigated using the run and Mann-Kendall tests. The significant trends are obtained from linear least-square fits. The annual and seasonal TMIN indices show significant warming trends with magnitudes (1.7°C per 100 years for annual index) comparable to those reported by the Intergovernmental Panel on Climate Change, but lower than those found for the southern Brazil in another previous work. Regarding the two other variables, the indices show significant trends only for summer, being a cooling trend of 0.6°C per 100 years for the TMAX and an increasing trend of 93 mm per 100 years over an average summer precipitation of 367 mm. Concerning the decadal analysis, the 1920s present the lowest annual, autumn, and spring TMIN and the 1990s, the highest ones. The 1970s is the decade with the lowest summer TMAX, and the 1940s the decade with the highest one. The driest decade is the 1940s and the wettest, the 1980s.

Sansigolo, Clóvis Angeli; Kayano, Mary Toshie

2010-07-01

73

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

74

Multivariate, non-linear trend analysis of heterogeneous water quality monitoring data  

NASA Astrophysics Data System (ADS)

Comprehensive water quality monitoring is considered a necessary prerequisite for sound water resources management and a valuable source for science. In practice, however, use of large monitoring data sets is often limited due to heterogeneous data sources, spatially and temporally variable monitoring schemes, non-equidistant sampling, large natural variability, and, last but not least, by the sheer size of the data sets that makes identification of unexpected peculiarities a tedious task. As a consequence, any initiation of gradual long-term system shifts can hardly be detected, especially as long as it is restricted to a small fraction of sampling sites. In addition, trends might be limited to a rather small subset of sampling sites or to certain periods of time and might thus escape attention. Usually, numerous solutes are monitored in parallel, but trend analyses are performed for each solute separately. However, in water quality samples trends are hardly restricted to single solutes, but affect various solutes synchronously in a characteristic way. Thus performing joint multivariate trend analyses would not only save effort and time, but would yield more robust assessments of system shifts. We present a non-linear multivariate data visualization approach that allows a rapid assessment of non-linear, possibly local trends and unexpected behaviour in large water quality monitoring data sets. It consists of a combination of Self-Organizing Maps and Sammon's Mapping (SOM-SM). The approach was applied to a data set of 2900 water samples, each comprising 13 solutes, compiled from various monitoring programs in the Federal State of Brandenburg (Germany). In total, 128 stream water, groundwater and small pond sites had been sampled between 1994 and 2012 at different and irregular time intervals. The SOM-SM product is a graph where every sample is represented by a symbol. Location of the symbols in the graph is optimized such that the distance between any two symbols in the graph is proportional to the dissimilarity of the two respective water samples with respect to all 13 solutes. In our study, the non-linear 2D projection of the SOM-SM reflected 75% of the variance of the 13D data set. For further analyses the same graph was used again and again, where different colouring revealed different information. Thus the user rapidly became acquainted with the large, high dimensional data set. At a first glance outliers easily could be identified as well as clusters of samples with similar solute concentration. Different groups of samples were analysed for the degree of overlap. Multivariate trend analysis was performed that did not only account for increasing or decreasing concentration of single solutes but for systemic shifts of characteristic solute concentration patterns as well. Partly converging trends were found, that is, sampling sites becoming more similar to each other. In addition, long-term decreasing variance was found at some sites. For checking for significant differences between different time periods confidence intervals were included in the graph. We conclude that the SOM-SM proved to be a powerful and extremely helpful tool for analysis of this large, heterogeneous water quality data set.

Lischeid, Gunnar; Kalettka, Thomas; Steidl, Jörg; Merz, Christoph; Lehr, Christian

2014-05-01

75

Contribution of stratospheric cooling to satellite-inferred tropospheric temperature trends.  

PubMed

From 1979 to 2001, temperatures observed globally by the mid-tropospheric channel of the satellite-borne Microwave Sounding Unit (MSU channel 2), as well as the inferred temperatures in the lower troposphere, show only small warming trends of less than 0.1 K per decade (refs 1-3). Surface temperatures based on in situ observations however, exhibit a larger warming of approximately 0.17 K per decade (refs 4, 5), and global climate models forced by combined anthropogenic and natural factors project an increase in tropospheric temperatures that is somewhat larger than the surface temperature increase. Here we show that trends in MSU channel 2 temperatures are weak because the instrument partly records stratospheric temperatures whose large cooling trend offsets the contributions of tropospheric warming. We quantify the stratospheric contribution to MSU channel 2 temperatures using MSU channel 4, which records only stratospheric temperatures. The resulting trend of reconstructed tropospheric temperatures from satellite data is physically consistent with the observed surface temperature trend. For the tropics, the tropospheric warming is approximately 1.6 times the surface warming, as expected for a moist adiabatic lapse rate. PMID:15129277

Fu, Qiang; Johanson, Celeste M; Warren, Stephen G; Seidel, Dian J

2004-05-01

76

Global crop exposure to critical high temperatures in the reproductive period: historical trends and future projections  

NASA Astrophysics Data System (ADS)

Long-term warming trends across the globe have shifted the distribution of temperature variability, such that what was once classified as extreme heat relative to local mean conditions has become more common. This is also true for agricultural regions, where exposure to extreme heat, particularly during key growth phases such as the reproductive period, can severely damage crop production in ways that are not captured by most crop models. Here, we analyze exposure of crops to physiologically critical temperatures in the reproductive stage (Tcrit), across the global harvested areas of maize, rice, soybean and wheat. Trends for the 1980-2011 period show a relatively weak correspondence (r = 0.19) between mean growing season temperature and Tcrit exposure trends, emphasizing the importance of separate analyses for Tcrit. Increasing Tcrit exposure in the past few decades is apparent for wheat in Central and South Asia and South America, and for maize in many diverse locations across the globe. Maize had the highest percentage (15%) of global harvested area exposed to at least five reproductive days over Tcrit in the 2000s, although this value is somewhat sensitive to the exact temperature used for the threshold. While there was relatively little sustained exposure to reproductive days over Tcrit for the other crops in the past few decades, all show increases with future warming. Using projections from climate models we estimate that by the 2030s, 31, 16, and 11% respectively of maize, rice, and wheat global harvested area will be exposed to at least five reproductive days over Tcrit in a typical year, with soybean much less affected. Both maize and rice exhibit non-linear increases with time, with total area exposed for rice projected to grow from 8% in the 2000s to 27% by the 2050s, and maize from 15 to 44% over the same period. While faster development should lead to earlier flowering, which would reduce reproductive extreme heat exposure for wheat on a global basis, this would have little impact for the other crops. Therefore, regardless of the impact of other global change factors (such as increasing atmospheric CO2), reproductive extreme heat exposure will pose risks for global crop production without adaptive measures such as changes in sowing dates, crop and variety switching, expansion of irrigation, and agricultural expansion into cooler areas.

Gourdji, Sharon M.; Sibley, Adam M.; Lobell, David B.

2013-06-01

77

Trends and Solar Cycle Effects in Temperature Versus Altitude From the Halogen Occultation Experiment for the Mesosphere and Upper Stratosphere  

NASA Technical Reports Server (NTRS)

Fourteen-year time series of mesospheric and upper stratospheric temperatures from the Halogen Occultation Experiment (HALOE) are analyzed and reported. The data have been binned according to ten-degree wide latitude zones from 40S to 40N and at 10 altitudes from 43 to 80 km-a total of 90 separate time series. Multiple linear regression (MLR) analysis techniques have been applied to those time series. This study focuses on resolving their 11-yr solar cycle (or SC-like) responses and their linear trend terms. Findings for T(z) from HALOE are compared directly with published results from ground-based Rayleigh lidar and rocketsonde measurements. SC-like responses from HALOE compare well with those from lidar station data at low latitudes. The cooling trends from HALOE also agree reasonably well with those from the lidar data for the concurrent decade. Cooling trends of the lower mesosphere from HALOE are not as large as those from rocketsondes and from lidar station time series of the previous two decades, presumably because the changes in the upper stratospheric ozone were near zero during the HALOE time period and did not affect those trends.

Remsberg, Ellis E.

2009-01-01

78

Ubiquity of linear resistivity at intermediate temperature in bad metals  

NASA Astrophysics Data System (ADS)

Bad metals display transport behavior that differs from what is commonly seen in ordinary metals. One of the most significant differences is a resistivity that is linear in temperature and rises to well above the Ioffe-Regel limit (where the mean-free path is equal to the lattice spacing). Using an exact Kubo formula, we show that a linear resistivity naturally occurs for many systems when they are in an incoherent intermediate-temperature state. First, we provide a simple analytic model to give intuition for this phenomenology. Then, we verify the analytic arguments with numerical calculations for a simplified version of the Hubbard model which is solved with dynamical mean-field theory. Similar features have also been seen in Hubbard models, where they can begin at even lower temperatures due to the formation of resilient quasiparticles.

Boyd, G. R.; Zlati?, V.; Freericks, J. K.

2015-02-01

79

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

80

Resistance thermometer has linear resistance-temperature coefficient at low temperatures  

NASA Technical Reports Server (NTRS)

Resistance thermometer incorporating a germanium resistance element with a platinum resistance element in a wheatstone bridge circuit has a linear temperature-resistance coefficient over a range from approximately minus 140 deg C to approximately minus 253 deg C.

Kuzyk, W.

1966-01-01

81

The identification of distinct patterns in California temperature trends  

Technology Transfer Automated Retrieval System (TEKTRAN)

Regional changes in California surface temperatures over the last 80 years are analyzed using station data from the US Historical Climate Network and the National Weather Service Cooperative Network. Statistical analyses using annual and seasonal temperature data over the last 80 years show distinct...

82

A stable boundary layer perspective on global temperature trends  

NASA Astrophysics Data System (ADS)

One of the most significant signals in the thermometer-observed temperature record since 1900 is the decrease in the diurnal temperature range over land, largely due to warming of the minimum temperatures. While some data sets have indicated this asymmetrical warming has been reduced since 1979, regional analyses (e.g. East Africa) indicate that the nocturnal warming continues at a pace greater than daytime temperatures. The cause for this night time warming in the observed temperatures has been attributed to a variety of causes. Climate models have in general not replicated the change in diurnal temperature range well. Here we would like to try to distinguish between warming in the nocturnal boundary layer due to a redistribution of heat and warming due to the accumulation of heat. The temperature at night at shelter height is a result of competition between thermal stability and mechanical shear. If stability wins then turbulence is suppressed and the cooling surface becomes cut-off from the warmer air aloft, which leads to sharp decay in surface air temperature. If shear wins, then turbulence is maintained and warmer air from aloft is continually mixed to the surface, which leads to significantly lower cooling rates and warmer temperatures. This warming occurs due to a redistribution of heat. As will be shown by techniques of nonlinear analysis the winner of the stability and shear contest can be very sensitive to changes in greenhouse gas forcing, surface roughness, cloudiness, and surface heat capacity (including soil moisture). Further, the minimum temperatures measured in the nocturnal boundary layer represent only a very shallow layer of the atmosphere which is usually only a few hundred meters thick. It is likely that the observed warming in minimum temperature, whether caused by additional greenhouse forcing or land use changes or other land surface dynamics, is reflecting a redistribution of heat by turbulence-not an accumulation of heat. Because minimum temperatures in the stable boundary layer are not very robust measures of the heat content in the deep atmosphere and climate models do not predict minimum temperatures well, minimum temperatures should not be used as a surrogate for measures of deep atmosphere global warming.

McNider, R. T.; Christy, J. R.; Biazar, A.

2010-08-01

83

Monitoring vegetation dynamics by coupling linear trend analysis with change vector analysis: a case study in the Xilingol steppe in northern China  

Microsoft Academic Search

Timely and accurate monitoring of grassland vegetation dynamics is essential for sustainable grassland management in China. We coupled linear trend analysis (LTA) with change vector analysis (CVA) to improve the effectiveness of grassland monitoring. LTA was used to detect continuous inter-annual vegetation trends to identify significant change trend regions (SCTRs) in location and significant change trend periods (SCTPs) in time.

Yuanyuan Zhao; Chunyang He; Qiaofeng Zhang

2012-01-01

84

Monitoring vegetation dynamics by coupling linear trend analysis with change vector analysis: a case study in the Xilingol steppe in northern China  

Microsoft Academic Search

Timely and accurate monitoring of grassland vegetation dynamics is essential for sustainable grassland management in China. We coupled linear trend analysis (LTA) with change vector analysis (CVA) to improve the effectiveness of grassland monitoring. LTA was used to detect continuous inter-annual vegetation trends to identify significant change trend regions (SCTRs) in location and significant change trend periods (SCTPs) in time.

Yuanyuan Zhao; Chunyang He; Qiaofeng Zhang

2011-01-01

85

Exospheric temperatures at Mars measured by SPICAM: seasonal trends  

NASA Astrophysics Data System (ADS)

A new analysis of the airglow spectra recorded by the UV spectrometer SPICAM onboard Mars Express is presented, with emphasis on the CO Cameron bands, the CO+2 (B-X) UV and OI (2972Å) emissions. Exospheric/ thermospheric temperatures are retrieved from the individual dayglow altitude profiles using a direct fit of the emission profiles by a set of barometric and Epstein functions and by adjusting the forward kinetic transport model Aeroplanets to fit the emission profiles. It is suggested that the CO+2 emission is the best candidate for an accurate retrieval of exospheric temperatures. Variations with solar longitude of the exospheric temperatures are investigated by the MTGCM global circulation model and compared with the observations. Reasonable agreement with observations is found for solar longitudes ranging from 140° to 300°, for solar minimum to moderate conditions.

Wedlund, C. Simon; Gronoff, G.; Bougher, S.

2011-10-01

86

Attribution of European precipitation and temperature trends to changes in circulation types  

NASA Astrophysics Data System (ADS)

Surface climate in Europe is changing and patterns in trends have been found to vary at sub-seasonal scales. This study aims to contribute to a better understanding of these changes across space and time by analysing to what degree observed climatic trends can be attributed to changes in atmospheric circulation. The relative importance of circulation changes (i.e. trends in circulation type frequencies) as opposed to trends in the hydrothermal properties of circulation types (within-type trends) on precipitation and temperature trends in Europe is assessed on a monthly basis. Gridded precipitation and temperature data originate from the Watch Forcing Dataset and circulation types (CTs) are defined by the objective SynopVis Grosswetterlagen. Relatively high influence of circulation changes are found from January to March, contributing to wetting trends in northern Europe and drying in the South. Simultaneously, in particular dry CTs get warmer first in south-western Europe in November/December and affecting most of Europe in March/April. Strong influence of circulation changes is again found in June and August. In general, circulation influence affects climate trends in north-western Europe stronger than the South-East. The exact locations of the strongest influence of circulation changes vary with time of the year and to some degree between precipitation and temperature. Throughout the year and across the whole of Europe, precipitation and temperature trends are caused by a combination of circulation changes and within-type changes with their relative influence varying between regions, months and climate variables.

Fleig, A. K.; Tallaksen, L. M.; James, P.; Hisdal, H.; Stahl, K.

2014-11-01

87

Wind Turbine Generator Condition-Monitoring Using Temperature Trend Analysis  

Microsoft Academic Search

Condition monitoring can greatly reduce the maintenance cost for a wind turbine. In this paper, a new condition-monitoring method based on the nonlinear state estimate technique for a wind turbine generator is proposed. The technique is used to construct the normal behavior model of the electrical generator temperature. A new and improved memory matrix construction method is adopted to achieve

Peng Guo; David Infield; Xiyun Yang

2012-01-01

88

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 B.; Haggerty, Roy; Hockman-Wert, David

2012-01-01

89

Temporal and spatial trend detection of maximum air temperature in Iran during 1960-2005  

NASA Astrophysics Data System (ADS)

Trends of maximum air temperature (T max) were investigated in three time scales including annual, seasonal, and monthly time series in 32 synoptic stations in the whole of Iran during 1960-2005. First, nonparametric Mann-Kendall test after removal of the lag-1 serial correlation component from the T max time series was used for trend detection and spatial distribution of various trends was mapped. Second, Sen's slope estimator was used to determine the median slope of positive or negative T max trends. Third, 10-year moving average low-pass filter was applied to facilitate the trend analysis and the smoothed time series derived from the mentioned filter were clustered in three clusters for each time series and then were plotted to show their spatial distribution patterns in Iran. Results showed that there are considerable significant positive trends of T max in warm months including April, June, July, August and September and warm seasons. These trends can be found in an annual time scale which indicated almost 50% positive trends. However, cold months and seasons did not exhibit a remarkable significant trend. Although it was rather difficult to detect particular spatial distribution of significant trends, some parts in west, north-east and south-east and central regions of the country showed more positive trends. In an annual time scale, Kermanshah located in west regions indicates most change at (+) 0.41 °C per decade. On the one hand, many clusters of normalized and filtered T max time series revealed the increasing trend after 1970 which has dramatically risen after around 1990. It is in accordance with many other findings for temperature time series from different countries and therefore, it can be generated from simultaneous changes in a bigger scale than regional one. On the other hand, the concentration of increasing trends of T max in warm seasons and their accordance to plants growing season in Iran can raise the importance of the role of frequent reported land use changes during past decades. Generally, the more sophisticated and comprehensive researches are needed to determine the role of different factors such as the emission of greenhouse gases and land use changes influencing temperature trends in Iran.

Kousari, Mohammad Reza; Ahani, Hossein; Hendi-zadeh, Razieh

2013-12-01

90

Long term water temperature behaviour and trends in a Devon, UK, river system  

Microsoft Academic Search

Data collected over a 14 year period (1977-1990) at three river stations have been used to study long term behaviour, trends and possible future changes of water temperature in the Exe Basin, Devon, UK. Long term mean temperatures are influenced by site elevation and catchment land use. Seasonal variation approximates a simple sine-generated curve and diurnal fluctuation is greater in

B. W. WEBB; D. E. WALLING

1993-01-01

91

Sulphate and desertification signals in Middle Eastern temperature trends  

SciTech Connect

Analysis of Middle Eastern annual temperature anomalies over the past 40 years reveals statistically significant warming over this time period of 0.07 C per decade. The warming is most pronounced over the spring season and least apparent in the winter season. Spatial analysis reveals a positive relationship between Middle Eastern warming and the degree of human-induced desertification and a negative relationship between local warming and the atmospheric concentration of sulphate.

Nasrallah, H.A. [Public Authority for Applied Education and Training (Kuwait); Balling, R.C. Jr. [Arizona State Univ., Tempe, AZ (United States). Office of Climatology

1994-12-31

92

Linear algebra of reduced units and discussion of temperature parameter  

E-print Network

A formal linear vector field representation for scientific equations is developed to rationalize the intuitive methods that are constantly employed. It is shown that unlike mechanical units that appear in the basis of the space, the reduced temperature and Boltzmann parameter cannot be described by the basis set individually and can only be described as a product. Further, the definition and determination of temperature is dependent on theory and not on standard mechanical units. It is shown that there is no reason to reduce the number of degrees of freedom in temperature determination via equipartition since stochastic variables are involved, and this observation is significant in that the temperature variable reported in simulation studies would have a discrepancy to the extent of using the decreased number of freedom, which is most cases is not large nor significant. The standard assignments used in reduced units do not lead to errors because operationally the resulting reduced temperature parameter represents the reduced product of the temperature and Boltzmann parameters. The non-independence of these quantities explains why entropy and other associated functions cannot be calculated directly, but are always scaled in dimensionless increments of the Boltzmann parameter.

Christopher G Jesudason

2004-03-03

93

Is there a trend in extremely high river temperature for the next decades? A case study for France  

NASA Astrophysics Data System (ADS)

After 2003's summer heat wave, Electricité de France created a global plan called "heat wave-dryness". In this context, the present study tries to estimate high river temperatures for the next decades, taking into account climatic and anthropogenic evolutions. To do it, a specific methodology based on Extreme Value Theory (EVT) is applied. In particular, a trend analysis of water temperature data is done and included in EVT used. The studied river temperatures consist of mean daily temperatures for 27 years measured near the French power plants (between 1977 and 2003), with four series for the Rhône river, four for the Loire river and a few for other rivers. There are also three series of mean daily temperatures computed by a numerical model. For each series, we have applied statistical extreme value modelling. Because of thermal inertia, the Generalized Extreme Value (GEV) distribution is corrected by the medium cluster length, which represents thermal inertia of water during extremely hot events. The ? and ? parameters of the GEV distributions are taken as polynomial or continuous piecewise linear functions of time. The best functions for ? and ? parameters are chosen using Akaike criterion based on likelihood and some physical checking. For all series, the trend is positive for ? and not significant for ?, over the last 27 years. However, we cannot assign this evolution only to the climatic change for the Rhône river because the river temperature is the resultant of several causes: hydraulic or atmospheric, natural or related to the human activity. For the other rivers, the trend for ? could be assigned to the climatic change more clearly. Furthermore, the sample is too short to provide reliable return levels estimations for return periods exceeding thirty years. Still, quantitative return levels could be compared with physical models for example.

Huguet, F.; Parey, S.; Dacunha-Castelle, D.; Malek, F.

2008-02-01

94

Output trends, characteristics, and measurements of three mega-voltage radiotherapy linear accelerators  

PubMed Central

The purpose of this study is to characterize and understand the long term behavior of the output from megavoltage radiotherapy linear accelerators. Output trends of nine beams from three linear accelerators over a period of more than three years are reported and analyzed. Output taken during daily warm-up forms the basis of this study. The output is measured using devices having ion-chambers. These are not calibrated by accredited dosimetry laboratory but are baseline compared against monthly output which are measured using calibrated ion-chambers. We consider the output from the daily check devices as it is and sometimes normalized them by the actual output measured during the monthly calibration of the Linacs. The data shows noisy quasi-periodic behavior. The output variation if normalized by monthly measured “real’ output, is bounded between ±3%. Beams of different energies from the same Linac are correlated with a correlation coefficient as high as 0.97 for one particular Linac and as low as 0.44 for another. These maximum and minimum correlations drop to 0.78 and 0.25 when daily output is normalized by the monthly measurements. These results suggest that the origin of these correlations are both the Linacs and the daily output check devices. Beams from different Linacs, independent of their energies, have lower correlation coefficient with a maximum of about 0.50 and a minimum of almost zero. The maximum correlation drops to almost zero if the output is normalized by the monthly measured output. Some scatter plots of pairs of beam-output from the same Linac show band-like structures. These structures are blurred when the output is normalized by the monthly calibrated output. Fourier decomposition of the quasi periodic output is consistent with a 1/f power law. The output variation appears to come from a distorted normal distribution with a mean of slightly greater than unity. The quasi-periodic behavior is manifested in the seasonally averaged output showing annual variability with negative variations in the winter and positive in the summer. This trend is weakened when the daily output is normalized by the monthly calibrated output indicating that the variation of the periodic component may be intrinsic to both the Linacs and the daily measurement devices. Actual Linac output was measured monthly. It is needed to be adjusted once every 3-6 months for our tolerance and action levels. If these adjustments are artificially removed then there is an increase in output of about 2-4% per year. PMID:25207404

Hossain, Murshed

2015-01-01

95

Temperature calculation of rectangular radiative fins using a linearized method  

NASA Astrophysics Data System (ADS)

An infinite series solution presented for a thin rectangular fin is developed for the steady temperature distribution in a two-dimensional rectangular sandwich panel fin heated within a rectangular footprint region, and losing energy to environment by linearized radiation. The solutions approximate a spacecraft application where a heat dissipating electronic component is mounted to a heat-sink plate or an equipment panel. The comparison of numerical results obtained from the proposed method and the lumped nodal method shows that the formulations will be useful in evaluating heat-sink designs where geometry, heat loads, thermal properties, and environmental parameters change frequently.

Nakajima, Katsuhiko; Miyasaka, Akihiro; Tsunoda, Hiroaki

96

MY NASA DATA: Surface Air Temperature Trends of the Caribbean  

NSDL National Science Digital Library

In this lesson, students will use real satellite data to determine the changes in near-surface air temperature over the Caribbean Sea at different times of the year. Step-by-step instructions for use of the MY NASA DATA Live Access Server (LAS) guide students through selecting a data set, importing the data into a spreadsheet, creating graphs, and analyzing data plots. The lesson provides detailed procedures, related links and sample graphs, follow-up questions, extensions, and teacher notes. Designed for student use, MY NASA DATA LAS samples micro datasets from large scientific data archives, and provides structured investigations engaging students in exploration of real data to answer real world questions.

2012-08-03

97

Global climate models’ bias in surface temperature trends and variability  

NASA Astrophysics Data System (ADS)

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

Davy, Richard; Esau, Igor

2014-11-01

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

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

100

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

101

Linear trends in salinity for the World Ocean, 19551998 Timothy P. Boyer, S. Levitus, J. I. Antonov, R. A. Locarnini, and H. E. Garcia  

E-print Network

Linear trends in salinity for the World Ocean, 1955­­1998 Timothy P. Boyer, S. Levitus, J. I; published 6 January 2005. [1] Quality controlled oceanographic profile salinity measurements from the World Ocean Database 2001 (WOD01) were used to calculate linear trends of zonally averaged salinity anomalies

102

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

103

Using Climate Divisions to Analyze Variations and Trends in Alaska Temperature and Precipitation  

E-print Network

recent decade. An exception to the cooling of the past decade is the North Slope climate division, which datasets used by the IPCC show warming over Alaska, typically about 18C and slightly greater in the northUsing Climate Divisions to Analyze Variations and Trends in Alaska Temperature and Precipitation

Bhatt, Uma

104

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

E-print Network

TEMPERATURE TRENDS AND THE DISTRIBUTION OF GROUNDFISH IN CONTINENTAL SHELF WATERS, NOVA SCOTIA in continental shelf waters between Nova Scotia and Long Island did not significantly alter the distribution stations from Nova Scotia to Cape Hatteras (Lauzier, 1965; Stearns, 196,'5; Welch, 1967). Coastal warming

105

Synchronous NDVI and surface air temperature trends in Newfoundland: 1982 to 2003  

Microsoft Academic Search

We investigated two unusual systematic normalized difference vegetation index (NDVI) growing season trends in Newfoundland from 1982 to 1999 within a satellite data record from 1982 to 2003 and attempted to determine their causes. We found direct correlations between increasing NDVI and increasing surface air temperature for the 1982–1990 and 1991–1999 growing seasons, punctuated by sharp simultaneous decreases in both

C. S. R. Neigh; C. J. Tucker; J. R. G. Townshend

2007-01-01

106

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

NASA Technical Reports Server (NTRS)

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

Dunkerton, Timothy J.

2000-01-01

107

Sea ice trends in the Antarctic and their relationship to surface air temperature during 19792009  

E-print Network

Sea ice trends in the Antarctic and their relationship to surface air temperature during 1979 in the Antarctic. It is found that the SAT variation from Goddard Institute for Space Studies (GISS) is the best ice and SAT in the Antarctic during 1979­2009. The Antarctic sea ice extent (SIE) shows an increased

Wang, Chunzai

108

Recent trends in daily temperature extremes over northeastern Spain (1960-2006)  

NASA Astrophysics Data System (ADS)

Spatial and temporal characteristics of extreme temperature events in northeastern Spain have been investigated. The analysis is based on long-term, high-quality, and homogenous daily maximum and minimum temperature of 128 observatories spanning the period from 1960 to 2006. A total of 21 indices were used to assess changes in both the cold and hot tails of the daily temperature distributions. The presence of trends in temperature extremes was assessed by means of the Mann-Kendall test. However, the autocorrelation function (ACF) and a bootstrap methodology were used to account for the influence of serial correlation and cross-correlation on the trend assessment. In general, the observed changes are more prevalent in hot extremes than in cold extremes. This finding can largely be linked to the increase found in the mean maximum temperature during the last few decades. The results indicate a significant increase in the frequency and intensity of most of the hot temperature extremes. An increase in warm nights (TN90p: 3.3 days decade-1), warm days (TX90p: 2.7 days decade-1), tropical nights (TR20: 0.6 days decade-1) and the annual high maximum temperature (TXx: 0.27 °C decade-1) was detected in the 47-yr period. In contrast, most of the indices related to cold temperature extremes (e.g. cold days (TX10p), cold nights (TN10p), very cold days (TN1p), and frost days (FD0)) demonstrated a decreasing but statistically insignificant trend. Although there is no evidence of a long-term trend in cold extremes, significant interdecadal variations were noted. Almost no significant trends in temperature variability indices (e.g. diurnal temperature range (DTR) and growing season length (GSL)) are detected. Spatially, the coastal areas along the Mediterranean Sea and the Cantabrian Sea experienced stronger warming compared with mainland areas. Given that only few earlier studies analyzed observed changes in temperature extremes at fine spatial resolution across the Iberian Peninsula, the results of this work can improve our understanding of climatology of temperature extremes. Also, these findings can have different hydrological, ecological and agricultural implications (e.g. crop yields, energy consumption, land use planning and water resources management).

El Kenawy, A.; López-Moreno, J. I.; Vicente-Serrano, S. M.

2011-09-01

109

Rising minimum temperature trends over India in recent decades: Implications for agricultural production  

NASA Astrophysics Data System (ADS)

The success of kharif crops in India is largely dependent on the performance of South west monsoon, whereas the rabi crops which are largely irrigated are sensitive to changes in temperature. Trends in minimum temperature for the period 1971-2009 were analyzed using 0.5° grid data for annual, kharif and rabi cropping seasons at the district level. Annual mean minimum temperature showed warming @ 0.24° 10 yr- 1 on all India basis. Large area (52.7% in kharif, 54.9% in rabi) showed strong and significant warming trend. The magnitude of rise in seasonal mean temperatures is more during rabi (0.28 °C 10 yr-1 ) compared to kharif (0.19 °C 10 yr-1 ). Kharif paddy yields in 268 districts across the country (57.2% of paddy growing area) were influenced by a rise in minimum temperature. Declines in kharif paddy yield ranged between 411 and 859 kg ha-1 per 1 °C rise in minimum temperature across regions. This warming trend is likely to continue with significant implication on crop yields and calls for development of suitable adaptation strategies to sustain production.

Bapuji Rao, B.; Santhibhushan Chowdary, P.; Sandeep, V. M.; Rao, V. U. M.; Venkateswarlu, B.

2014-06-01

110

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

111

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

NASA Astrophysics Data System (ADS)

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

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

1997-08-01

112

Recent surface temperature trends in the interior of East Antarctica from borehole firn temperature measurements and geophysical inverse methods  

NASA Astrophysics Data System (ADS)

We use measured firn temperatures down to depths of 80 to 90 m at four locations in the interior of Dronning Maud Land, East Antarctica to derive surface temperature histories spanning the past few decades using two different inverse methods. We find that the mean surface temperatures near the ice divide (the highest-elevation ridge of East Antarctic Ice Sheet) have increased approximately 1 to 1.5 K within the past ˜50 years, although the onset and rate of this warming vary by site. Histories at two locations, NUS07-5 (78.65°S, 35.64°E) and NUS07-7 (82.07°S, 54.89°E), suggest that the majority of this warming took place in the past one or two decades. Slight cooling to no change was indicated at one location, NUS08-5 (82.63°S, 17.87°E), off the divide near the Recovery Lakes region. In the most recent decade, inversion results indicate both cooler and warmer periods at different sites due to high interannual variability and relatively high resolution of the inverted surface temperature histories. The overall results of our analysis fit a pattern of recent climate trends emerging from several sources of the Antarctic temperature reconstructions: there is a contrast in surface temperature trends possibly related to altitude in this part of East Antarctica.

Muto, Atsuhiro; Scambos, Ted A.; Steffen, Konrad; Slater, Andrew G.; Clow, Gary D.

2011-08-01

113

Recent surface temperature trends in the interior of East Antarctica from borehole firn temperature measurements and geophysical inverse methods  

USGS Publications Warehouse

We use measured firn temperatures down to depths of 80 to 90 m at four locations in the interior of Dronning Maud Land, East Antarctica to derive surface temperature histories spanning the past few decades using two different inverse methods. We find that the mean surface temperatures near the ice divide (the highest-elevation ridge of East Antarctic Ice Sheet) have increased approximately 1 to 1.5 K within the past ???50 years, although the onset and rate of this warming vary by site. Histories at two locations, NUS07-5 (78.65S, 35.64E) and NUS07-7 (82.07S, 54.89E), suggest that the majority of this warming took place in the past one or two decades. Slight cooling to no change was indicated at one location, NUS08-5 (82.63S, 17.87E), off the divide near the Recovery Lakes region. In the most recent decade, inversion results indicate both cooler and warmer periods at different sites due to high interannual variability and relatively high resolution of the inverted surface temperature histories. The overall results of our analysis fit a pattern of recent climate trends emerging from several sources of the Antarctic temperature reconstructions: there is a contrast in surface temperature trends possibly related to altitude in this part of East Antarctica. Copyright 2011 by the American Geophysical Union.

Muto, A.; Scambos, T.A.; Steffen, K.; Slater, A.G.; Clow, G.D.

2011-01-01

114

MY NASA DATA: Trends in Snow Cover and Temperature in Alaska  

NSDL National Science Digital Library

This lesson is designed to help students gain knowledge in using the MY NASA DATA Live Access Server (LAS) to specify and download a microset of data, and then to use the data to compare NASA satellite observations data with surface measurements of snow cover and temperature. Students will obtain snow cover and surface temperature data for a locale in Alaska, plot the data, and then investigate seasonal trends in snow cover, and the relationship between snow cover and surface temperature at that locale. The lesson provides detailed procedure, related links and sample graphs, follow-up questions and extensions, and Teacher Notes.

2006-04-10

115

Statistical analysis of long term spatial and temporal trends of temperature parameters over Sutlej river basin, India  

NASA Astrophysics Data System (ADS)

The annual and seasonal trend analysis of different surface temperature parameters (average, maximum, minimum and diurnal temperature range) has been done for historical (1971-2005) and future periods (2011-2099) in the middle catchment of Sutlej river basin, India. The future time series of temperature data has been generated through statistical downscaling from large scale predictors of CGCM3 and HadCM3 models under A2 scenario. Modified Mann-Kendall test and Cumulative Sum (CUSUM) chart have been used for detecting trend and sequential shift in time series of temperature parameters. The results of annual trend analysis for period of 1971-2005 show increasing as well as decreasing trends in average (T Mean), maximum (T Max), minimum (T Min) temperature and increasing trends in Diurnal Temperature Range (DTR) at different stations. But the annual trend analysis of downscaled data has revealed statistically significant (95% confidence level) rising trends in T Mean, T Max, T Min and falling trend in DTR for the period 2011-2099. The decreasing trend in DTR is due to higher rate of increase in T Min compared to T Max.

Singh, Dharmaveer; Glupta, R. D.; Jain, Sanjay K.

2015-02-01

116

Statistical analysis of long term spatial and temporal trends of temperature parameters over Sutlej river basin, India  

NASA Astrophysics Data System (ADS)

The annual and seasonal trend analysis of different surface temperature parameters (average, maximum, minimum and diurnal temperature range) has been done for historical (1971-2005) and future periods (2011-2099) in the middle catchment of Sutlej river basin, India. The future time series of temperature data has been generated through statistical downscaling from large scale predictors of CGCM3 and HadCM3 models under A2 scenario. Modified Mann-Kendall test and Cumulative Sum (CUSUM) chart have been used for detecting trend and sequential shift in time series of temperature parameters. The results of annual trend analysis for period of 1971-2005 show increasing as well as decreasing trends in average ( T Mean), maximum ( T Max), minimum ( T Min) temperature and increasing trends in Diurnal Temperature Range (DTR) at different stations. But the annual trend analysis of downscaled data has revealed statistically significant (95% confidence level) rising trends in T Mean, T Max, T Min and falling trend in DTR for the period 2011-2099. The decreasing trend in DTR is due to higher rate of increase in T Min compared to T Max.

Singh, Dharmaveer; Glupta, R. D.; Jain, Sanjay K.

2015-02-01

117

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

118

Lattice vacancies responsible for the linear dependence of the low-temperature heat capacity of insulating materials  

NASA Astrophysics Data System (ADS)

The linear dependence on temperature (? T ) of the heat capacity at low temperatures (T <15 K ) is traditionally attributed to conduction electrons in metals; however, many insulators also exhibit a linear dependence that has been attributed to a variety of other physical properties. The property most commonly used to justify the presence of this linear dependence is lattice vacancies, but a correlation between these two properties has never been shown, to our knowledge. We have devised a theory that justifies a linear heat capacity as a result of lattice vacancies, and we provide measured values and data from the literature to support our arguments. We postulate that many small Schottky anomalies are produced by a puckering of the lattice around these vacancies, and variations in the lattice caused by position or proximity to some form of structure result in a distribution of Schottky anomalies with different energies. We present a mathematical model to describe these anomalies and their distribution based on literature data that ultimately results in a linear heat capacity. From these calculations, a quantitative relationship between the linear term and the concentration of lattice vacancies is identified, and we verify these calculations using values of ? and vacancy concentrations for several materials. We have compiled many values of ? and vacancy concentrations from the literature which show several significant trends that provide further evidence for our theory.

Schliesser, Jacob M.; Woodfield, Brian F.

2015-01-01

119

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

120

A Reanalysis for the Seasonal and Longer-Period Cycles and the Trends in Middle Atmosphere Temperature from the HALOE  

NASA Technical Reports Server (NTRS)

Previously published analyses for the seasonal and longer-period cycles in middle atmosphere temperature versus pressure (or T(p)) from the Halogen Occultation Experiment (HALOE) are extended to just over 14 years and updated to properly account for the effects of autocorrelation in its time series of zonally-averaged data. The updated seasonal terms and annual averages are provided, and they can be used to generate temperature distributions that are representative of the period 1991-2005. QBO-like terms have also been resolved and are provided, and they exhibit good consistency across the range of latitudes and pressure-altitudes. Further, exploratory analyses of the residuals from each of the 221 time series have yielded significant 11-yr solar cycle (or SC-like) and linear trend terms at a number of latitudes and levels. The amplitudes of the SC-like terms for the upper mesosphere agree reasonably with calculations of the direct solar radiative effects for T(p). Those SC amplitudes increase by about a factor of 2 from the lower to the upper mesosphere and are also larger at the middle than at the low latitudes. The diagnosed cooling trends for the subtropical latitudes are in the range, -0.5 to -1.0 K/decade, which is in good agreement with the findings from models of the radiative effects on pressure surfaces due to known increases in atmospheric CO2. The diagnosed trends are somewhat larger than predicted with models for the upper mesosphere of the northern hemisphere middle latitudes.

Remsberg, Ellis E.

2007-01-01

121

Tropical temperature trends in Atmospheric General Circulation Model simulations and the impact of uncertainties in observed SSTs  

NASA Astrophysics Data System (ADS)

The comparison of trends in various climate indices in observations and models is of fundamental importance for judging the credibility of climate projections. Tropical tropospheric temperature trends have attracted particular attention as this comparison may suggest a model deficiency. One can think of this problem as composed of two parts: one focused on tropical surface temperature trends and the associated issues related to forcing, feedbacks, and ocean heat uptake and a second part focusing on connections between surface and tropospheric temperatures and the vertical profile of trends in temperature. Here we focus on the atmospheric component of the problem. We show that two ensembles of Geophysical Fluid Dynamics Laboratory HiRAM model runs (similar results are shown for National Center for Atmospheric Research's CAM4 model) with different commonly used prescribed sea surface temperatures (SSTs), namely, the HadISST1 and "Hurrell" data sets, have a difference in upper tropical tropospheric temperature trends (˜0.1 K/decade at 300 hPa for the period 1984-2008) that is about a factor 3 larger than expected from moist adiabatic scaling of the tropical average SST trend difference. We show that this surprisingly large discrepancy in temperature trends is a consequence of SST trend differences being largest in regions of deep convection. Further, trends, and the degree of agreement with observations, not only depend on SST data set and the particular atmospheric temperature data set but also on the period chosen for comparison. Due to the large impact on atmospheric temperatures, these systematic uncertainties in SSTs need to be resolved before the fidelity of climate models' tropical temperature trend profiles can be assessed.

Flannaghan, T. J.; Fueglistaler, S.; Held, I. M.; Po-Chedley, S.; Wyman, B.; Zhao, M.

2014-12-01

122

21st Century Trends in Antarctic Temperature and Polar Stratospheric Cloud (PSC) Area in the GEOS Chemistry-Climate Model  

NASA Technical Reports Server (NTRS)

This study examines trends in Antarctic temperature and APSC, a temperature proxy for the area of polar stratospheric clouds, in an ensemble of Goddard Earth Observing System (GEOS) chemistry-climate model (CCM) simulations of the 21st century. A selection of greenhouse gas, ozone-depleting substance, and sea surface temperature scenarios is used to test the trend sensitivity to these parameters. One scenario is used to compare temperature trends in two versions of the GEOS CCM. An extended austral winter season is examined in detail. In May, June, and July, the expected future increase in CO2-related radiative cooling drives temperature trends in the Antarctic lower stratosphere. At 50 hPa, a 1.3 K cooling is expected between 2000 and 2100. Ozone levels increase, despite this robust cooling signal and the consequent increase in APSC, suggesting the enhancement of stratospheric transport in future. In the lower stratosphere, the choice of climate change scenarios does not affect the magnitude of the early winter cooling. Midwinter temperature trends are generally small. In October, APSC trends have the same sign as the prescribed halogen trends. That is, there are negative APSC trends in "grealistic future" simulations, where halogen loading decreases in accordance with the Montreal Protocol and CO2 continues to increase. In these simulations, the speed of ozone recovery is not influenced by either the choice of sea surface temperature and greenhouse gas scenarios or by the model version.

Hurwitz, M. M.; Newman, P. A.

2010-01-01

123

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

124

Difficulties in Obtaining Reliable Temperature Trends: Reconciling the Surface and Satellite Microwave Sounding Unit Records  

Microsoft Academic Search

A chronic difficulty in obtaining reliable climate records from satellites has been changes in instruments, platforms, equator-crossing times, and algorithms. The microwave sounding unit (MSU) tropospheric temperature record has overcome some of these problems, but evidence is presented that it too contains unreliable trends over a 17-yr period (1979-95) because of transitions involving different satellites and complications arising from nonatmospheric

James W. Hurrell; Kevin E. Trenberth

1998-01-01

125

Recent climatic trends in nearshore water temperatures in the St. Lawrence Great Lakes  

Microsoft Academic Search

In the Great Lakes region, the observational evidence for climatic change has been primarily limited to changes in lake-ice conditions, with no long-term trends identified in water temperatures. Seven nearshore water intake sites (Bay City, Michigan; Green Bay, Wisconsin; Sault Ste. Marie, Michigan; St. Joseph, Michigan; Sandusky Bay, Ohio; Put-In-Bay, Ohio; and Erie, Pennsylvania) in the Great Lakes were chosen,

Michael J. McCormick; Gary L. Fahnenstiel

1999-01-01

126

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

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

Mean annual temperature and total annual precipitation trends at Canadian biosphere reserves.  

PubMed

This article examines instrumental climate records from a variety of stations associated with the following Biosphere Reserves across Canada: (i) Waterton Lakes, (ii) Riding Mountain, (iii) Niagara Escarpment, (iv) Long Point, and (v) Kejimkujik (Candidate Biosphere Reserve). Annual series are generated from daily temperature and precipitation values. In addition, homogeneous data are used from other stations and regional records to supplement the records from the local biosphere stations. Long term trends are identified over the period of the instrumental record. In general, data from the interval 1900 to 1998 show cooler temperatures in the 1920's, warming from the early 1940's into the early 1950's, cooling into the 1970's, and subsequent warming. At many stations, 1998 is the warmest in the instrumental record. Comparisons with the regional data sets show good agreements between the temperature series. The 20th century warming is approximately 1.0 degree C in the Riding Mountain area and 0.6 degrees C in the Long Point, Niagara Escarpment, and Waterton Lakes areas. There has been slight cooling in the Kejimkujik area over the past half century. Precipitation data show increasing trends in the Kejimkujik. Long Point, Niagara Escarpment, and Waterton Lakes areas with no long term trend in the Riding Mountain area. This work is part of the Canadian Biosphere Reserves Association (CBRA) Climate Change Initiative (CCI), designed to present climate change information to Biosphere Reserve communities to allow local organizations to understand climate change and adapt to potential impacts. PMID:11339701

Hamilton, J P; Whitelaw, G S; Fenech, A

2001-01-01

129

Validation of electron temperature gradient turbulence in the Columbia Linear Machine  

E-print Network

Validation of electron temperature gradient turbulence in the Columbia Linear Machine X. R. Fu,1 W; published online 6 March 2012) The electron temperature gradient (ETG) mode, which is a universal mechanism hydrogen plasma of the Columbia Linear Machine. Electron temperature profiles with strong gradients

Lin, Zhihong

130

High temperature garnet growth in New England: regional temperature-time trends revealed  

NASA Astrophysics Data System (ADS)

A series of localized ultrahigh-temperature (UHT)/high-temperature (HT) granulite facies regions have been identified within the regional amphibolite facies metamorphic zone of the Central Maine Terrane stretching from north-central New Hampshire, through central Massachusetts, and into northeastern Connecticut. Here, we aim to constrain the age and peak temperature of metamorphism at three localities within this region: Bristol, NH, Phillipston, MA and Willington, CT. Garnet-forming reactions are linked directly to peak metamorphic temperatures through thermodynamic modeling and/or Zr-in-rutile thermometry. Precise garnet geochronology allows us to identify the timing of these peak temperatures, as well as the duration of garnet growth. Geochronologic and thermodynamic work was done on 12 samples collected throughout a ~5 km2 metamorphic 'hotspot' previously identified in Bristol, NH (Chamberlain and Rumble, 1988; Journal of Petrology). The highest temperature assemblage within this hotspot is characterized by the presence of garnet + sillimanite + K-feldspar + cordierite and reached temperatures >820?C. The lowest temperature periphery of the hotspot is characterized by sillimanite + muscovite + K-feldspar + minor garnet and reached a maximum temperature of 650?C. Bulk garnet ages from samples within the hotspot range significantly from at least 400.0 × 2.5 Ma to 352.7 × 1.8 Ma with the youngest ages associated with the lower temperature samples. This collection of ages indicates a prolonged period (~50 Ma) of >650?C temperatures interspersed by period(s) of garnet growth. Zoned garnet geochronology will help reveal whether garnet growth and related heating was continuous or episodic. Further south, in Phillipston, MA, zoned garnet geochronology performed on a 2.5 cm diameter garnet porphyroblast indicates garnet growth spanning 389 - 363 Ma, reaching peak temperatures at the end of that time span of 920-940?C, followed by a younger event recorded in smaller 1-3mm garnet crystals at 351 Ma (which may also reflect resetting of the earlier event), reaching similar temperatures of 920-960?C. These temperatures were obtained by Zr-in-rutile thermometry performed on rutile inclusions within the garnet. Even farther south, in the UHT zone around Willington, CT, temperatures of at least 1000?C were determined using Zr-in-rutile thermometry on rutile inclusions in garnet and reintegration of ternary feldspar compositions (Ague et al., 2013; Geology). The garnet age for a representative UHT sample from this site is 340.3 × 1.7 Ma. The geochronologic data presented here indicates a prolonged period of UHT/HT garnet growth within the Central Maine Terrane, beginning at ~400 Ma in Bristol, NH and ending at ~340 Ma in Willington, CT. Peak temperatures are >820?C in NH, >950?C in MA, and ~1000?C in CT, resulting in a regional pattern of increasing temperature with decreasing age from north to south across this 250 km long region.

Sullivan, N.; Ostwald, C.; Chu, X.; Baxter, E. F.; Ague, J. J.; Eckert, J. O.

2013-12-01

131

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

132

Seasonal trends in precipitation and surface air temperature extremes in mainland Portugal, 1941-2007  

NASA Astrophysics Data System (ADS)

Several climate models predict, on a global scale, modifications in climate variables that are expected to have impact on society and the environment. The concern is on changes in the variability of processes, the mean and extreme events (maximum and minimum). To explore recent changes in precipitation and near surface air temperature extremes in mainland Portugal, we have inspected trends in time series of specific indices defined for daily data. These indices were recommended by the Commission for Climatology/Climate Variability and Predictability (CCl/CLIVAR) Working Group on Climate Change Detection, and include threshold indices, probability indices, duration indices and other indices. The precipitation and air temperature data used in this study are from, respectively, 57 and 23 measuring stations scattered across mainland Portugal, and cover the periods 1941-2007, for precipitation, and 1941-2006, for temperature. The study focuses on changes at the seasonal scale. Strong seasonality is one of the main features of climate in mainland Portugal. Intensification of the seasonality signal across the territory, particularly in the more sensitive regions, might contribute to endanger already fragile soil and water resources and ecosystems, and the local environmental and economic sustainability. Thus, the understanding of variations in the intensity, frequency and duration of extreme precipitation and air temperature events at the intra-annual scale is particularly important in this geographical area. Trend analyses were conducted over the full period of the records and for sub-periods, exploring patterns of change. Results show, on the one hand, regional differences in the tendency observed in the time series analysed; and, on the other hand, that although trends in annual indices are in general not statistically significant, there are sometimes significant changes over time in the data at the seasonal scale that point out to an increase in the already existing asymmetries in the climate in mainland Portugal, including changes in the extremes of precipitation and surface air temperature.

de Lima, M. I. P.; Santo, F. E.; Ramos, A. M.

2012-04-01

133

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.

134

Uncertainties Evaluation of Temperature Trends from Multiple Radiosondes, Microwave Sounding Units and Reanalyses Products  

NASA Astrophysics Data System (ADS)

Based on the ensemble spread, a methodology of measuring uncertainty in weather forecasts, the temperature trend and spread have been estimated using five radiosonde data sets, three Microwave Sounding Units (MSU: STAR, RSS and UAH) retrieved productions and seven reanalysis products beginning in 1979. The results show that the magnitude of warming or cooling depends on the data sources, atmospheric heights, and geophysical latitudes. For global mean temperature, the trend is approximately 0.2 K/decade in the troposphere and -0.8 K/decade in the stratosphere. The spread increases significantly with atmospheric height from approximately 0.1 K/decade at 850hPa to 0.8 K/decade at 30hPa. The spread in the reanalyses data sets is much larger than in the radiosondes and MSU in the stratosphere. In contrast, the spread in the reanalyses, MSU and radiosondes data sets is very small and shows the trend in better agreement with each other in the troposphere.

Powell, A. M.; Xu, J.

2010-12-01

135

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

136

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

137

Recent annual and seasonal temperature trends for a Trans-Pyrenean region, 1950-2008  

NASA Astrophysics Data System (ADS)

Estimation of multidecadal trends in regional temperatures has remained a key indicator of global warming. Here we show a preliminary approach analyzing surface temperature series for a trans-pyrenean region involving three different countries (Andorra, Catalonia and south-eastern France), representing different climate regimes and covering the period 1950-2008. The monthly data employed in this work was obtained after careful quality control of daily values. The QC'd dataset was homogenised usig the available metadata and the Cassinus-Mestre (C-M) method, both for breakpoint detection and series correction. C-M is a pair-wise comparison procedure which uses a bayesian approach to detect multiple changes and avoids problems associated with reference series (e.g. difficulties in ensuring homogeneity and mixture of record lengths in climate series) and enables all temperature series to be evaluated. This work was carried out within the action COST-ES0601: Advances in homogenisation methods of climate series: an integrated approach (HOME), which has among its goals to investigate the impacts of different homogenisation approaches over the observed data series. The results show a similar positive annual temperature trend over the whole region and period (1950-2008) of about +0.20°C/decade, and being statistically significant (p

Prohom, M. J.; Aguilar, E.; Esteban, P.; Mestre, O.

2009-09-01

138

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

139

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

140

An analysis of the meteorological variables leading to apparent temperature in Australia: Present climate, trends, and global warming simulations  

NASA Astrophysics Data System (ADS)

This study is a comprehensive analysis of thermal comfort and apparent temperature around Australia. It includes a long-term historical trend analysis using observational weather station data, in which it was found that eight out of the ten chosen urban locations experienced warming trends in temperature and/or the apparent temperature over the second half of the twentieth century. Annual trends in temperature and apparent temperature were studied spatially across Australia using high resolution ERA Interim reanalysis data over the period 1979 to 2010. The reanalysis revealed that generally the apparent temperature is warming faster than the air temperature, amplifying the expected exposure to discomfort due to global warming in the subtropical region.

Jacobs, Stephanie J.; Pezza, Alexandre B.; Barras, Vaughan; Bye, John; Vihma, Timo

2013-08-01

141

Inference of Global Mean Temperature Trend and Climate Change from MSU and AMSU  

NASA Technical Reports Server (NTRS)

Microwave Sounding Unit (MSU) and Advanced MSU (AMSU) radiometers flown on the NOAA operational satellite series are potentially valuable as global temperature monitoring devices. Spencer and Christy pioneered the analysis of mid-tropospheric temperature, given by MSU Channel 2 (Ch 2) at 53.74 GHz, to derive the global temperature trend. Also, in addition to monitoring global temperature, these microwave radiometers have the potential to reveal interannual climate signals in tropics. We have analyzed the data of MSU Ch 2 and AMSU Ch 5 (53.6 GHz) from the NOAA operational satellites for the period 1980 to 2000, utilizing the NOAA calibration procedure. The data are corrected for the satellite orbital drift based on the temporal changes of the on-board warm blackbody temperature. From our analysis, we find that the global temperature increased at a rate of 0.13 +/- 0.05 Kdecade(sup -1) during 1980 to 2000. From an Empirical Orthogonal Function (EOF) analysis of the MSU global data, we find that the mid-tropospheric temperature in middle and high latitudes responds to the ENSO forcing during the Northern Hemisphere Winter in a distinct manner. This mid-latitude response is opposite in phase to that in the tropics. This result is in accord with simulations performed with an ECMWF global spectral model. This study shows a potential use of the satellite observations for climatic change.

Prabhakara, Cuddapah; Iacovazzi, R. A., Jr.; Yoo, J.-M.; Lau, William K. M. (Technical Monitor)

2001-01-01

142

Influence trend of temperature distribution in skin tissue generated by different exposure dose pulse laser  

NASA Astrophysics Data System (ADS)

Laser is widely applied in military and medicine fields because of its excellent capability. In order to effectively defend excess damage by laser, the thermal processing theory of skin tissue generated by laser should be carried out. The heating rate and thermal damage area should be studied. The mathematics model of bio-tissue heat transfer that is irradiated by laser is analyzed. And boundary conditions of bio-tissue are discussed. Three layer FEM grid model of bio-tissue is established. The temperature rising inducing by pulse laser in the tissue is modeled numerically by adopting ANSYS software. The changing trend of temperature in the tissue is imitated and studied under the conditions of different exposure dose pulse laser. The results show that temperature rising in the tissue depends on the parameters of pulse laser largely. In the same conditions, the pulse width of laser is smaller and its instant power is higher. And temperature rising effect in the tissue is very clear. On the contrary, temperature rising effect in the tissue is lower. The cooling time inducing by temperature rising effect in the tissue is longer along with pulse separation of laser is bigger. And the temperature difference is bigger in the pulse period.

Shan, Ning; Wang, Zhijing; Liu, Xia

2014-11-01

143

Confinement driven effects in a room temperature ferroelectric liquid crystal: X-ray, linear and non-linear dielectric investigations  

Microsoft Academic Search

We present results of X-ray, linear and non-linear dielectric constant measurements on a room temperature ferroelectric liquid crystalline phase in its bulk form and upon confinement in an Anopore membrane. The used material exhibits smectic C* (SmC*) helical pitch of p???200?nm, which is comparable to the pore dimension of the membrane. X-ray measurements show several interesting results including unusually strong

M. Vijay Kumar; S. Krishna Prasad; D. S. Shankar Rao; E. P. Pozhidaev

2012-01-01

144

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

145

Global trends in lake surface temperatures observed using multi-sensor thermal infrared imagery  

NASA Astrophysics Data System (ADS)

Recent research has shown that the temperature of lakes and other inland water bodies does not only act as a good indicator of climate variability but under certain conditions can even increase more rapidly than the regional air temperature. Further investigation of this phenomenon in particular and of the interaction between lake temperature and climate variability in general requires extensive observations of lake temperature on a global scale. Current in situ records are limited in their spatial and/or temporal coverage and are thus insufficient for this task. However, a nearly 30-year archive of satellite-derived thermal infrared imagery from multiple sensors is available at this point and can be used to fill this data gap. We describe research on utilizing the existing archive of spaceborne thermal infrared imagery to generate multi-decadal time series of lake surface temperature for 170 of the largest lakes worldwide. The data used for this purpose includes imagery from the Advanced Very High Resolution Radiometers (AVHRR), the series of (Advanced) Along-Track Scanning Radiometers ((A)ATSR), and the Moderate Resolution Imaging Spectroradiometer (MODIS). Used in combination, these data sets offer a gapless time series of daily to near-daily thermal infrared retrievals from 1981 through present. In this contribution we demonstrate using comprehensive in situ data at Lake Tahoe, California/Nevada, that lake water surface temperature can be estimated using these sensors with an accuracy of up to 0.2 K. We further show that accurate continuous time series of water surface temperature can be derived from the data and that these time series can be used to detect significant trends in the temporal thermal behavior of lakes and other inland water bodies worldwide. Complementing our recent case study for lakes in California and Nevada for which a rapid increase in mean nighttime summertime lake surface temperatures of 0.11 K per year on average was found, we present first results of an extended global study of worldwide trends in lake temperatures, indicating that the majority of lakes studied has been warming significantly over the last few decades. We further discuss distinct regional patterns in these trends and how they relate to spatial patterns in recently observed global air temperature increase. Using a multi-sensor archive of thermal infrared imagery, the research performed within the framework of this study for the first time allows a unique, global-scale, and consistent perspective on the temporal thermal properties of large inland water bodies worldwide, in particular for the vast majority of lakes for which no in situ data is available. This facilitates the construction of continuous surface temperature time series for the last few decades as well as the detection of trends in the lakes' temporal thermal behavior. As such, the results of this study are important with respect to ongoing research on the impact of global climate change on lake ecosystems as well as the interaction between large lakes and regional climate.

Schneider, Philipp; Hook, Simon J.; Radocinski, Robert G.; Corlett, Gary K.; Hulley, Glynn C.; Schladow, S. Geoffrey; Steissberg, Todd E.

2010-05-01

146

Solar variations and their influence on trends in upper stratospheric ozone and temperature  

SciTech Connect

Over the past decade, knowledge of the magnitude and temporal structure of the variations in the sun's ultraviolet irradiance has increased steadily. A number of theoretical modeling studies have shown that changes in the solar ultraviolet flux during the 11-year solar cycle can have a significant effect on stratospheric ozone concentrations. With the exception of Brasseur et al., who examined a very broad range of solar flux variations, all of these studies assumed much larger changes in the ultraviolet flux than measurements now indicate. These studies either calculated the steady-state effect at solar maximum and solar minimum or assumed sinusoidal variations in the solar flux changes with time. It is now possible to narrow the uncertainty range of the expected effects on upper stratospheric ozone and temperature resulting from the 11-year solar cycle. A more accurate representation of the solar flux changes with time is used in this analysis, as compared to previous published studies. This study also evaluates the relative roles of solar flux variations and increasing concentrations of long-lived trace gases in determining the observed trends in upper stratospheric ozone and temperature. The LLNL two-dimensional chemical-radiative-transport model of the global atmosphere is used to evaluate the combined effects on the stratosphere from changes in solar ultraviolet irradiances and trace gas concentrations over the last several decades. Derived trends in upper stratospheric ozone concentrations and temperature are then compared with available analyses of ground-based and satellite measurements over this time period.

Wuebbles, D.J.; Kinnison, D.E. (Lawrence Livermore National Lab., CA (USA)); Lean, J.L. (Naval Research Lab., Washington, DC (USA). E.O. Hulburt Center for Space Research)

1990-10-01

147

Usefulness of AIRS-Derived OLR, Temperature, Water vapor and Cloudiness Anomaly Trends for GCM Validation  

NASA Astrophysics Data System (ADS)

Mainly due to their global nature, satellite observations can provide a very useful basis for GCM validations. In particular, satellite sounders such as AIRS provide 3-D spatial information (most useful for GCMs), so the question arises: can we use AIRS datasets for climate variability assessments? We show that the recent (September 2002 - February 2010) CERES-observed negative trend in OLR of ~-0.1 W/m2/yr averaged over the globe is found in the AIRS OLR data as well. Most importantly, even minute details (down to 1 x 1 degree GCM-scale resolution) of spatial and temporal anomalies and trends of OLR as observed by CERES and computed based on AIRS-retrieved surface and atmospheric geophysical parameters over this time period are essentially the same. The correspondance can be seen even in the very large spatial variations of these trends with local values ranging from -2.6 W/m2/yr to +3.0 W/m2/yr in the tropics, for example. This essentially perfect agreement of OLR anomalies and trends derived from observations by two different instruments, in totally independent and different manners, implies that both sets of results must be highly accurate, and indirectly validates the anomalies and trends of other AIRS derived products as well. These products show that global and regional anomalies and trends of OLR, water vapor and cloud cover over the last 7+ years are strongly influenced by El-Niño-La Niña cycles . We have created climate parameter anomaly datasets using AIRS retrievals which can be compared directly with coupled GCM climate variability assesments. Moreover, interrelationships of these anomalies and trends should also be similar between the observed and GCM-generated datasets, and, in cases of discrepancies, GCM parameterizations could be improved based on the relationships observed in the data. First, we assess spatial “trends” of variability of climatic parameter anomalies [since anomalies relative to the seasonal cycle are good proxies of climate variability] at the common 1x1 degree GCM grid-scale by creating spatial anomaly “trends” based on the first 7+ years of AIRS Version 5 Level3 data. We suggest that modelers should compare these with their (coupled) GCM’s performance covering the same period. We evaluate temporal variability and interrelations of climatic anomalies on global to regional e.g., deep Tropical Hovmoller diagrams, El-Niño-related variability scales, and show the effects of El-Niño-La Niña activity on tropical anomalies and trends of water vapor cloud cover and OLR. For GCMs to be trusted highly for long-term climate change predictions, they should be able to reproduce findings similar to these. In summary, the AIRS-based climate variability analyses provide high quality, informative and physically plausible interrelationships among OLR, temperature, humidity and cloud cover both on the spatial and temporal scales. GCM validations can use these results even directly, e. g., by creating 1x1 degree trendmaps for the same period in coupled climate simulations.

Molnar, G. I.; Susskind, J.; Iredell, L. F.; NASA/Gsfc Sounder Research Team

2010-12-01

148

Usefulness of AIRS-Derived OLR, Temperature, Water Vapor and Cloudiness Anomaly Trends for GCM Validation  

NASA Technical Reports Server (NTRS)

Mainly due to their global nature, satellite observations can provide a very useful basis for GCM validations. In particular, satellite sounders such as AIRS provide 3-D spatial information (most useful for GCMs), so the question arises: can we use AIRS datasets for climate variability assessments? We show that the recent (September 2002 February 2010) CERES-observed negative trend in OLR of approx.-0.1 W/sq m/yr averaged over the globe is found in the AIRS OLR data as well. Most importantly, even minute details (down to 1 x 1 degree GCM-scale resolution) of spatial and temporal anomalies and trends of OLR as observed by CERES and computed based on AIRS-retrieved surface and atmospheric geophysical parameters over this time period are essentially the same. The correspondence can be seen even in the very large spatial variations of these trends with local values ranging from -2.6 W/sq m/yr to +3.0 W/sq m/yr in the tropics, for example. This essentially perfect agreement of OLR anomalies and trends derived from observations by two different instruments, in totally independent and different manners, implies that both sets of results must be highly accurate, and indirectly validates the anomalies and trends of other AIRS derived products as well. These products show that global and regional anomalies and trends of OLR, water vapor and cloud cover over the last 7+ years are strongly influenced by EI-Nino-La Nina cycles . We have created climate parameter anomaly datasets using AIRS retrievals which can be compared directly with coupled GCM climate variability assessments. Moreover, interrelationships of these anomalies and trends should also be similar between the observed and GCM-generated datasets, and, in cases of discrepancies, GCM parameterizations could be improved based on the relationships observed in the data. First, we assess spatial "trends" of variability of climatic parameter anomalies [since anomalies relative to the seasonal cycle are good proxies of climate variability] at the common 1x1 degree GCM grid-scale by creating spatial anomaly "trends" based on the first 7+ years of AIRS Version 5 Leve13 data. We suggest that modelers should compare these with their (coupled) GCM's performance covering the same period. We evaluate temporal variability and interrelations of climatic anomalies on global to regional e.g., deep Tropical Hovmoller diagrams, El-Nino-related variability scales, and show the effects of El-Nino-La Nina activity on tropical anomalies and trends of water vapor cloud cover and OLR. For GCMs to be trusted highly for long-term climate change predictions, they should be able to reproduce findings similar to these. In summary, the AIRS-based climate variability analyses provide high quality, informative and physically plausible interrelationships among OLR, temperature, humidity and cloud cover both on the spatial and temporal scales. GCM validations can use these results even directly, e. g., by creating 1x1 degree trendmaps for the same period in coupled climate simulations.

Molnar, Gyula I.; Susskind, Joel; Iredell, Lena F.

2010-01-01

149

Climatology and trends of summer high temperature days in India during 1969-2013  

NASA Astrophysics Data System (ADS)

Based on the daily maximum air temperature data from 176 stations in India from 1969 to 2013, the climatological distribution of the number of days with high temperature (HT) defined as days with maximum temperature higher than 37°C during summer season (March-June) are studied. With a focus on the regional variability and long-term trends, the impacts of HT days are examined by dividing the country into six geographical regions (North, West, North-central, East, South-central and South). Although the long-term (1969-2013) climatological numbers of HT days display well-defined spatial patterns, there is clear change in climatological mean and coefficient of variation of HT days in a recent period (1991-2013). The long period trends indicate increase in summer HT days by 3%, 5%, and 18% in north, west, and south regions, respectively and decrease by 4% and 9% in north-central and east regions respectively. However, spatial variations in HT days exist across different regions in the country. The data analysis shows that 2010 was the warmest summer year and 2013 was the coolest summer year in India. Comparison of spatial distributions of trends in HT days for 1969-1990 and 1991-2013 periods reveal that there is an abrupt increase in the number of HT days over north, west and north-central regions of India probably from mid 1990s. A steep increase in summer HT days in highly populated cities of Mumbai, New Delhi, Chennai, Jaipur, and Visakhapatnam is noticed during the recent period of 1991-2013. The summer HT days over southern India indicate significant positive correlation with Nino 3.4 index for three months' running mean (December-January-February, January-March, February-April, March-May and April-June).

Jaswal, A. K.; Rao, P. C. S.; Singh, Virendra

2015-02-01

150

Observed Trends in Indices of Daily Precipitation and Temperature Extremes in Rio de Janeiro State (brazil)  

NASA Astrophysics Data System (ADS)

One of the main concerns of contemporary society regarding prevailing climate change is related to possible changes in the frequency and intensity of extreme events. Strong heat and cold waves, droughts, severe floods, and other climatic extremes have been of great interest to researchers because of its huge impact on the environment and population, causing high monetary damages and, in some cases, loss of life. The frequency and intensity of extreme events associated with precipitation and air temperature have been increased in several regions of the planet in recent years. These changes produce serious impacts on human activities such as agriculture, health, urban planning and development and management of water resources. In this paper, we analyze the trends in indices of climatic extremes related to daily precipitation and maximum and minimum temperatures at 22 meteorological stations of the National Institute of Meteorology (INMET) in Rio de Janeiro State (Brazil) in the last 50 years. The present trends are evaluated using the software RClimdex (Canadian Meteorological Service) and are also subjected to statistical tests. Preliminary results indicate that periods of drought are getting longer in Rio de Janeiro State, except in the North/Northwest area. In "Vale do Paraíba", "Região Serrana" and "Região dos Lagos" the increase of consecutive dry days is statistically significant. However, we also detected an increase in the total annual rainfall all over the State (taxes varying from +2 to +8 mm/year), which are statistically significant at "Região Serrana". Moreover, the intensity of heavy rainfall is also growing in most of Rio de Janeiro, except in "Costa Verde". The trends of heavy rainfall indices show significant increase in the "Metropolitan Region" and in "Região Serrana", factor that increases the vulnerability to natural disasters in these areas. With respect to temperature, it is found that the frequency of hot (cold) days and nights is increasing (reducing) with significance in almost all regions. "Região dos Lagos" has the most significant trends of increasing in temperature, thereby influencing the local production of salt and alkaline minerals in medium and long term. The goal of this research is, through the analysis of results, support studies of vulnerability and adaptation to climate change scenarios in Rio de Janeiro State.

Silva, W. L.; Dereczynski, C. P.; Cavalcanti, I. F.

2013-05-01

151

Trends of Temperature and Signature of Solar Activity in Selected Stations in Nigeria  

NASA Astrophysics Data System (ADS)

This study investigates the variability and periodicity of minimum temperature, maximum tem- perature and sunspot number - a solar activity index in selected synoptic stations across Nigeria from 1946 to 2010. Annual and semiannual effect of solar activity on minimum temperature was observed in all the six stations. This was indicated in the occurrence of modal periodicities of 6- month and 12-month observed across the six synoptic stations. The synoptic stations are Sokoto (13.01°N, 5.15°E), Ilorin (8.29°N, 4.35°E), Ikeja (6.35°N, 3.20°E), Enugu (6.28°N, 7.33°E), Port-Harcourt (4.51°N, 7.01°E) and Maiduguri (11.51°N, 13.05°E). Similarly, the trends of inter-decadal variability of minimum and maximum temperature show a non-uniformity increase over the analyzed period with a slight decrease before 1960. The long term behavior of minimum and maximum temperature shows a warming rate which ranges from 0.1°C/decade to 0.2°C/ decade across the six stations except for maximum temperature at Ilorin and minimum temperature at Sokoto which is at -0.2°C/decade and 0.3°C/decade respectively.

Olusegun, C. F.; Rabiu, A. B.; Ndeda, J. O. H.; Okogbue, E. C.

2014-04-01

152

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

153

The impact of high-performance computing in the solution of linear systems: trends and problems  

Microsoft Academic Search

We review the influence of the advent of high-performance computing on the solution of linear equations. We will concentrate on direct methods of solution and consider both the case when the coefficient matrix is dense and when it is sparse. We will examine the current performance of software in this area and speculate on what advances we might expect in

Iain S. Duff

2000-01-01

154

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

155

Raman distributed temperature sensor for oil leakage detection in soil: a field trial and future trends  

NASA Astrophysics Data System (ADS)

In this paper we perform field validation of distributed Raman temperature sensing (RDTS) for oil leakage detection in soil. The capability of the distributed Raman sensor in detecting and locating, with high accuracy and spatial resolution, drop leakages in soil is demonstrated through a water leakage simulation in a field trial. The future trends and the high potential of the Raman DTS technology for oil and gas leakage detection in long pipelines is then outlined in this paper by reporting lab experiments demonstrating accurate meter scale temperature measurement over more than 50 km of standard single mode fiber. The proposed solution, based on distributed Simplex coding techniques, can be competitive in terms of cost and performance with respect to other distributed sensing technologies.

Signorini, Alessandro; Nannipieri, Tiziano; Gabella, Luca; Di Pasquale, Fabrizio; Latini, Gilberto; Ripari, Daniele

2014-05-01

156

Full-depth temperature trends in the northeastern Atlantic through the early 21st century  

NASA Astrophysics Data System (ADS)

The vertical structure of temperature trends in the northeastern Atlantic (NEA) is investigated using a blend of Argo and hydrography data. The representativeness of sparse hydrography sampling in the basin mean is assessed using a numerical model. Between 2003 and 2013, the NEA underwent a strong surface cooling (0-450 m) and a significant warming at intermediate and deep levels (1000 m to 3000 m) that followed a strong cooling trend observed between 1988 and 2003. During 2003-2013, gyre-specific changes are found in the upper 1000 m (warming and cooling of the subtropical and subpolar gyres, respectively), while the intermediate and deep warming primarily occurred in the subpolar gyre, with important contributions from isopycnal heave and water mass property changes. The full-depth temperature change requires a local downward heat flux of 0.53 ± 0.06 W m-2 through the sea surface, and its vertical distribution highlights the likely important role of the NEA in the recent global warming hiatus.

Desbruyères, D. G.; McDonagh, E. L.; King, B. A.; Garry, F. K.; Blaker, A. T.; Moat, B. I.; Mercier, H.

2014-11-01

157

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

NASA Astrophysics Data System (ADS)

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

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

2015-03-01

158

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

159

Assessing the reliability of trends in extremes of surface temperature across Europe in the ERA-Interim reanalysis dataset  

NASA Astrophysics Data System (ADS)

Reanalysis data are often used in climate studies as a surrogate for observations. This is particularly the case in model comparisons, where the spatial/temporal completeness of the reanalysis data allows direct comparisons with simulated data. However, reanalysis data are susceptible to certain limitations, including changes to the observed data input over time, deficiencies in the data-assimilation scheme and uncertainties in the numerical model. Temporal inhomogeneities arising from the increasing incorporation of remotely-sensed data since the late 1970s have been a significant problem in earlier reanalysis versions, and have confounded trend evaluations in such datasets. Assessments of the reliability of reanalysis data compared to observed data is therefore vital, particularly with regard to long-term trends. Most previous comparisons have evaluated trends in mean values, and have shown that the ERA-Interim data are generally good at replicating trends in means of surface temperature in data-rich areas such as Europe. Relatively few attempts have been made to evaluate trends in extreme values derived from reanalysis data. In this paper, trends in extremes of daily maximum/minimum temperature across Europe in the ERA-Interim reanalysis dataset over the period 1980-2011 are compared with trends in both station data and the gridded E-OBS dataset. Reanalysis temperature data that have been post-processed at 3- and 12-hourly resolutions are used, and the numbers of days per season/year that daily maximum/minimum temperature exceeded the 10th and 90th base-period percentiles are employed as metrics (TX10/90 and TN10/90 respectively). The results in this paper indicate that, on the whole, the trends in temperature extremes are successfully replicated in the ERA-Interim reanalysis. The data are least successful in the spring and summer months and for the TX90 index. Significant trend differences are observed at certain high-elevation sites, where trends in extremes of maximum temperature in particular tend to be underestimated. The time-resolution of the post-processed temperature reanalysis data also appears to have an effect on the depiction of trends in temperature extremes, with the 3-hourly resolution data out-performing the 12-hourly data.

Cornes, Richard; Jones, Phil

2014-05-01

160

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

161

Statistical analysis of stratospheric temperature and ozone profile data for trends and model comparison. Final report, 1 July 1990-30 June 1992  

SciTech Connect

Work performed during the project period July 1, 1990 to June 30, 1992 on the statistical analysis of stratospheric temperature data, rawinsonde temperature data, and ozone profile data for the detection of trends is described. Our principal topics of research are trend analysis of NOAA stratospheric temperature data over the period 1978-1989; trend analysis of rawinsonde temperature data for the period 1964-1988; trend analysis of Umkehr ozone profile data for the period 1977-1991; and comparison of observed ozone and temperature trends in the lower stratosphere. Analysis of NOAA stratospheric temperature data indicates the existence of large negative trends at 0.4 mb level, with magnitudes increasing with latitudes away from the equator. Trend analysis of rawinsonde temperature data over 184 stations shows significant positive trends about 0.2 C per decade at surface to 500 mb range, decreasing to negative trends about -0.3 C at 100 to 50 mb range, and increasing slightly at 30 mb level. There is little evidence of seasonal variation in trends. Analysis of Umkehr ozone data for 12 northern hemispheric stations shows significant negative trends about -.5 percent per year in Umkehr layers 7-9 and layer 3, but somewhat less negative trends in layers 4-6. There is no pronounced seasonal variation in trends, especially in layers 4-9. A comparison was made of empirical temperature trends from rawinsonde data in the lower stratosphere with temperature changes determined from a one-dimensional radiative transfer calculation that prescribed a given ozone change over the altitude region, surface to 50 km, obtained from trend analysis of ozonsonde and Umkehr profile data. The empirical and calculated temperature trends are found in substantive agreement in profile shape and magnitude.

Tiao, G.C.

1992-11-01

162

Long-term midlatitude mesopause region temperature trend deduced from quarter century (1990-2014) Na lidar observations  

NASA Astrophysics Data System (ADS)

The long-term midlatitude temperature trend between 85 and 105 km is deduced from 25 years (March 1990-December 2014) of Na Lidar observations. With a strong warming episode in the 1990s, the time series was least-square fitted to an 11-parameter nonlinear function. This yields a cooling trend starting from an insignificant value of 0.64 ± 0.99 K decade-1 at 85 km, increasing to a maximum of 2.8 ± 0.58 K decade-1 between 91 and 93 km, and then decreasing to a warming trend above 103 km. The geographic altitude dependence of the trend is in general agreement with model predictions. To shed light on the nature of the warming episode, we show that the recently reported prolonged global surface temperature cooling after the Mt Pinatubo eruption can also be very well represented by the same response function.

She, C.-Y.; Krueger, D. A.; Yuan, T.

2015-03-01

163

Trends in the design of front-end systems for room temperature solid state detectors  

SciTech Connect

The paper discusses the present trends in the design of low-noise front-end systems for room temperature semiconductor detectors. The technological advancement provided by submicron CMOS and BiCMOS processes is examined from several points of view. The noise performances are a fundamental issue in most detector applications and suitable attention is devoted to them for the purpose of judging whether or not the present processes supersede the solutions featuring a field-effect transistor as a front-end element. However, other considerations are also important in judging how well a monolithic technology suits the front-end design. Among them, the way a technology lends itself to the realization of additional functions, for instance, the charge reset in a charge-sensitive loop or the time-variant filters featuring the special weighting functions that may be requested in some applications of CdTe or CZT detectors.

Manfredi, Pier F.; Re, Valerio

2003-10-07

164

Interrelations of AIRS/AMSU-derived anomalies and trends of temperature, water vapor, clouds and OLR  

NASA Astrophysics Data System (ADS)

The AIRS/AMSU instrument is currently the best space-based tool to simultaneously monitor the vertical distribution of key climatically important atmospheric parameters as well as surface properties and has been providing high quality data for more than 7 years. Currently, general circulation models (GCMs) are our best tools for longer-term climate change predictions. However, there are large uncertainties in their climate feedback strengths, in particular those related to atmospheric moisture. Here, we illustrate that even relatively shorter-term observed climate parameter variabilities, measured with high enough quality, could provide useful insights about climate feedbacks and may serve as constraints on theoretical and GCM-computed feedback mechanisms. Anomalies relative to the mean seasonal cycle of 7 years worth of data are indicative of various climate forcings and feedbacks, especially in periods containing strong El Niño/La Niña oscillations. This work is based on publicly available Version 5 Level3 AIRS analysis results produced at the GODDARD/DISC. Following the presentation of AIRS-anomaly validations, using available independent satellite data analysis results, we continue with an assessment of interrelationships of AIRS-observed anomalies of various climate parameters at different spatial scales. We also present AIRS-retrievals-based global, regional and 1x1 degree grid-scale “trend”-analyses of important atmospheric parameters for this 7+ year period. Note that here “trend” simply means the linear fit to the anomaly time series of various parameters at the above-mentioned spatial scales. Correlations among the anomaly timeseries and relevant Hovmoller diagrams reveal how selected climate feedbacks operate on various spatial scales. We find especially meaningful correlations over the El Niño/La Niña affected regions. These observed correlations may also provide constraints on model implementations/manifestations of climate feedback processes and illustrate the usefulness of continuing the high quality AIRS-based climate variability measurements.

Molnar, G. I.; Susskind, J.

2009-12-01

165

Annual temperature anomaly trends correlate with coral reef trajectory across the Pacific  

NASA Astrophysics Data System (ADS)

The future survival of coral reefs depends on the envelope of critical climatic conditions determining the severity of impacts on the ecosystem. While coral health is strongly determined by extreme heat events, that lead to bleaching and often death, chronic "heat loading" may also disadvantage corals by making them more susceptible to, for example, diseases. On the other hand, it has been shown that coral living in hotter areas have higher bleaching thresholds and may be affected by less mortality at extreme events. This level at which heat anomalies lead to coral mortality varies widely across oceans, from ~31 deg C across the Caribbean to ~32 deg C in the Great Barrier Reef to 37.5 deg C in the Persian/Arabian Gulf. Thus, there clearly exists local adaptation and the extremes required to kill reefs strongly vary among regions. This could be be interpreted as suggesting that as long as bleaching temperatures are not reached, increased overall heat content expressed by a positive annual thermal anomaly, might actually foster coral resilience. Is there evidence for or against such an argument? Bleaching events have been occurring worldwide with variable recurrence and variable subsequent recovery. Despite demonstrated adaptation to higher-than-usual mean summer temperatures, reefs in the Arabian Gulf and the Red Sea are on a declining trajectory. This coincides with consistent warming in the region. Mean annual anomalies of ocean temperature (since 1870) and atmospheric temperatures (since 1950) increase throughout the region. Since 1994 (Red Sea) and 1998 (southern Arabian Gulf) all mean annual anomalies have been positive and this period has coincided with repeated, severe bleaching events. In the Eastern Pacific (Galapagos and Easter Island), the trend of mean annual temperature anomalies has been declining and coral cover has been increasing. Thus, trends in coral cover and mean annual anomaly are negatively correlated in both regions. Despite strong impacts due to bleaching in 1983 and 1998, and increasing variance in anomalies (both positive and negative) the E-Pacific presently maintains an upward trend in coral cover and colony frequency. In the Red Sea , variance in anomalies increased but exclusively towards positive values. In the Gulf, variance declined towards stronger and only positive anomalies. In both regions, this raised thermal envelope is associated with reef decline. This is most dramatic in the Gulf, with six bleaching events since 1996, but also obvious in the Red Sea (bleaching in 1998, 2005 and 2010). Both Gulf and Red Sea suffer also from other mortality factors, such as diseases and predator outbreaks. Decline in reef health is therefore not uniquely linked to bleaching, but other mortality factors are also linked to changes in the thermal envelope. Chronic effects of increased average temperatures seem to define a reef trajectory more closely than the effects of individual, albeit strong, episodic disturbances.

Riegl, B. M.; Wieters, E.; Bruckner, A.; Purkis, S.

2013-05-01

166

Seasonal lake surface water temperature trends reflected by heterocyst glycolipid based molecular thermometers  

NASA Astrophysics Data System (ADS)

It has been demonstrated that the relative distribution of heterocyst glycolipids (HGs) in cultures of N2-fixing heterocystous cyanobacteria is largely controlled by growth temperature, suggesting a potential use of these components in paleoenvironmental studies. Here, we investigated the effect of environmental parameters (e.g. surface water temperatures, oxygen concentrations and pH) on the distribution of HGs in a natural system using water column filtrates collected from Lake Schreventeich (Kiel, Germany) from late July to the end of October 2013. HPLC-ESI/MS analysis revealed a dominance of 1-(O-hexose)-3,25-hexacosanediols (HG26 diols) and 1-(O-hexose)-3-keto-25-hexacosanol (HG26 keto-ol) in the solvent extracted water column filtrates, which were accompanied by minor abundances of 1-(O-hexose)-3,27-octacosanediol (HG28 diol) and 1-(O-hexose)-3-keto-27-octacosanol (HG28 keto-ol) as well as 1-(O-hexose)-3,25,27-octacosanetriol (HG28 triol) and 1-(O-hexose)-3-keto-25,27-octacosanediol (HG28 keto-diol). Fractional abundances of alcoholic and ketonic HGs generally showed strong linear correlations with surface water temperatures and no or only weak linear correlations with both oxygen concentrations and pH. Changes in the distribution of the most abundant diol and keto-ol (e.g., HG26 diol and HG26 keto-ol) were quantitatively expressed as the HDI26 (heterocyst diol index of 26carbon atoms) with values of this index ranging from 0.89 in mid-August to 0.66 in mid-October. An average HDI26 value of 0.79, which translates into a calculated surface water temperature of 15.8 ± 0.3 °C, was obtained from surface sediments collected from Lake Schreventeich. This temperature - and temperatures obtained from other HG indices (e.g., HDI28 and HTI28) - is similar to the one measured during maximum cyanobacterial productivity in early to mid-September and suggests that HGs preserved in Lake Schreventeich sediments record summer surface water temperatures. As N2-fixing heterocystous cyanobacteria are widespread in present-day freshwater and brackish environments, we conclude that the distribution of HGs in sediments may allow the reconstruction of surface water temperatures of modern and potentially ancient lacustrine settings.

Bauersachs, T.; Rochelmeier, J.; Schwark, L.

2015-01-01

167

30-Year Mid-Tropospheric Temperature Trends over the Polar Regions Using MSU/AMSU-A Data  

NASA Astrophysics Data System (ADS)

The Polar Regions play important roles in global climate change. The Arctic is experiencing the greatest rates of change during the past decades compared to other regions. The Microwave Sounding Unit (MSU) and Advanced Microwave Sounding Unit A (AMSU-A) onboard the National Oceanic and Atmospheric Administration (NOAA) and the European Meteorological Operational satellite programme (MetOp) satellites provide unique long-term measurements for monitoring atmospheric temperature trends. However, trends derived from MSU/AMSU-A observations are still under debate until today. Moreover, previous studies used limited data and few works focused on the Polar Regions. In this study, we investigated the mid-tropospheric temperature trends over the Polar Regions using 30-year MSU/AMSU-A observations (Nov. 1978 - Jun. 2009, NOAA-TIROS N through NOAA-18 and MetOp-A). Calibration error is a major source of uncertainty because the intersatellite biases between different sensors can be as large as 1 K in the NOAA operational calibrated L1B products. We used the NOAA/NESDIS/STAR reprocessed/recalibrated L1C datasets based on Simultaneous Nadir Overpass (SNO) intercalibration method (Zou et al., 2009, Zou et al., 2006). It reduces intersatellite biases by up to an order of magnitude compared to pre-launch calibration by using a more accurate estimation of the sensor nonlinearity. Mid-tropospheric temperature trends over the Arctic (60° N - 82.5° N) and Antarctic (60° S - 82.5° S) were analyzed using the well-merged time series for MSU channel 2 and AMSU-A channel 5. Our results indicated the Arctic has warmed by 0.31 K/Decade during the past 30 years, more than two times the rate of global warming trend. The Antarctic has cooled by -0.10 K/Decade. Fig. 1 (a) and (b) show the spatial patterns of mid-tropospheric temperature trends from Nov. 1978 to Jun. 2009. Warming trends prevail over the Arctic, contrasted by the general cooling trends over the Antarctic. Significant warming occurred over the Arctic from Jan. 1987 to Sep. 2006, with trends larger than 0.8 K/Decade over portions of the Greenland, Baffin Bay, and Baffin Island. The Antarctic Continent and western/southern Southern Ocean also show warming trends during this 10-year period. Fig. 1 Spatial patterns of MSU/AMSU-A mid-tropospheric temperature trends over the Polar Regions.

Wang, W.; Zou, C.

2009-12-01

168

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

169

An objective determination of optimal site locations for detecting expected trends in upper-air temperature and total column ozone  

NASA Astrophysics Data System (ADS)

In the first study reported on here, requirements on random uncertainty of instantaneous temperature measurements, sampling frequency, season and pressure, required to ensure a minimum random uncertainty of monthly mean temperatures, have been explored. These results then inform analyses conducted in a second study which seeks to identify the optimal location of sites for detecting projected trends in upper-air temperatures in the shortest possible time. The third part of the paper presents a similar analysis for the optimal locations of sites to detect projected trends in total column ozone. Results from the first study show that only for individual measurement random uncertainties > 0.2 K does the measurement random uncertainty start to contribute significantly to the random uncertainty of the monthly mean. Analysis of the effects of the individual measurement random uncertainty and sampling strategy on the ability to detect upper-air temperature trends shows that only when the measurement random uncertainty exceeds 2 K, and measurements are made just once or twice a month, is the quality of the trend determination compromised. The time to detect a trend in some upper-air climate variable is a function of the unforced variance in the signal, the degree of autocorrelation, and the expected magnitude of the trend. For middle tropospheric and lower stratospheric temperatures, the first two quantities were derived from Microwave Sounding Unit (MSU) and Advanced Microwave Sounding Unit (AMSU) measurements while projected trends were obtained by averaging 21st century trends from simulations made by 11 chemistry-climate models (CCMs). For total column ozone, variance and autocorrelation were derived from the Bodeker Scientific total column ozone database with projected trends obtained from median values from 21 CCM simulations of total column ozone changes over the 21st century. While the optimal sites identified in this analysis for detecting temperature and total column ozone trends in the shortest time possible result from our use of only one of a wide range of objective strategies, these results provide additional incentives for initiating measurement programmes at these sites or, if already in operation, to continue to be supported.

Kreher, K.; Bodeker, G. E.; Sigmond, M.

2015-01-01

170

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

171

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

172

[The linearity analysis of ultrahigh temperature FTIR spectral emissivity measurement system].  

PubMed

To study thermal radiation properties of special materials at high temperature in aerospace fields, the ultrahigh temperature spectral emissivity measurement system with Fourier spectrometer has been established. The linearity of system is the guarantee of emissivity measurement precision. Through measuring spectral radiation signals of a blackbody source at different temperatures, the function relations between spectral signal values and blackbody spectral radiation luminance of every spectrum points were calculated with the method of multi-temperature and multi-spectrum linear fitting. The spectral radiation signals of blackbody were measured between 1 000 degrees C and 2 000 degrees C in the spectral region from 3 to 20 microm. The linear relations between spectral signal and theory line at wavelength of 4 microm were calculated and introduced. The spectral response is well good between 4 and 18 microm, the spectral linearity are less than 1% except CO2 strong absorption spectrum regions. The results show that when the errors of measured spectrum radiation and linear fitting theory lines are certain, the higher the temperature, the smaller the spectral errors on emissivity. The linearity analysis of spectrum response is good at eliminating errors caused by individual temperature' disturbance to the spectra. PMID:22512159

Wang, Zong-wei; Dai, Jing-min; He, Xiao-wa; Yang, Chun-ling

2012-02-01

173

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

174

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

2015-01-01

175

Temperature Trends in the Tropical Upper Troposphere and Lower Stratosphere: Connections with Sea Surface Temperatures and Implications for Water Vapor and Ozone  

NASA Technical Reports Server (NTRS)

Satellite observations and chemistry-climate model experiments are used to understand the zonal structure of tropical lower stratospheric temperature, water vapor, and ozone trends. The warming in the tropical upper troposphere over the past 30 years is strongest near the Indo-Pacific warm pool, while the warming trend in the western and central Pacific is much weaker. In the lower stratosphere, these trends are reversed: the historical cooling trend is strongest over the Indo-Pacific warm pool and is weakest in the western and central Pacific. These zonal variations are stronger than the zonal-mean response in boreal winter. Targeted experiments with a chemistry-climate model are used to demonstrate that sea surface temperature (hereafter SST) trends are driving the zonal asymmetry in upper tropospheric and lower stratospheric tropical temperature trends. Warming SSTs in the Indian Ocean and in the warm pool region have led to enhanced moist heating in the upper troposphere, and in turn to a Gill-like response that extends into the lower stratosphere. The anomalous circulation has led to zonal structure in the ozone and water vapor trends near the tropopause, and subsequently to less water vapor entering the stratosphere. The radiative impact of these changes in trace gases is smaller than the direct impact of the moist heating. Projected future SSTs appear to drive a temperature and water vapor response whose zonal structure is similar to the historical response. In the lower stratosphere, the changes in water vapor and temperature due to projected future SSTs are of similar strength to, though slightly weaker than, that due directly to projected future CO2, ozone, and methane.

Garfinkel, C. I.; Waugh, D. W.; Oman, L. D.; Wang, L.; Hurwitz, M. M.

2013-01-01

176

Chemical Reaction Effects on MHD Flow Past a Linearly Accelerated Vertical Plate with Variable Temperature and Mass Diffusion in the Presence of Thermal Radiation  

NASA Astrophysics Data System (ADS)

An exact solution of first order chemical reaction effects on a radiative flow past a linearly accelerated infinite isothermal vertical plate with variable mass diffusion, under the action of a transversely applied magnetic field has been presented. The plate temperature is raised linearly with time and the concentration level near the plate is also raised to C'w linearly with time. The dimensionless governing equations are tackled using the Laplace-transform technique. The velocity, temperature and concentration fields are studied for different physical parameters such as the magnetic field parameter, radiation parameter, chemical reaction parameter, thermal Grashof number, mass Grashof number, Schmidt number, Prandtl number and time. It is observed that velocity increases with decreasing magnetic field parameter or radiation parameter. But the trend is just reversed with respect to the chemical reaction parameter

Muthucumaraswamy, R.; Geetha, E.

2013-08-01

177

Recent trends in Inner Asian forest dynamics to temperature and precipitation indicate high sensitivity to climate change  

NASA Astrophysics Data System (ADS)

Semi-arid ecosystems play an important role in regulating global climate and their response to climate change will depend on interactions between temperature, precipitation, and CO2. However, in cool-arid environments, precipitation is not the only limitation to forest productivity. For example, interactions between changes in precipitation and air temperature may enhance soil moisture stress while simultaneously extending growing season length, with unclear consequences for net carbon uptake. This presentation evaluates recent trends in productivity and seasonality of forests located in Inner Asia (Mongolia and Northern China) using satellite remote sensing, dendrochronology, and dynamic global vegetation model (DGVM) simulations to quantify the sensitivity of forest dynamics to decadal climate variability and trends. Long-term trends from satellite observations of FPAR between 1982-2010 show a greening of 21% of the region in spring (March, April May), but with 10% of the area 'browning' during summertime (June, July, August), the results of which are corroborated by trends in NPP simulated by the LPJ DGVM. Spring greening trends in FPAR are mainly explained by long-term trends in precipitation whereas summer browning trends are correlated with decreasing precipitation. Tree ring data from 25 sites confirm annual growth increments are mainly limited by summer precipitation (June, July, August) in Mongolia, and spring precipitation in northern China (March, April, May), with relatively weak prior-year lag effects. An ensemble of climate projections from the IPCC CMIP3 models indicates that warming temperatures (spring, summer) are expected to be associated with higher summer precipitation, which combined with CO2 causes large increases in NPP and eventual increase in forest cover in the Mongolian steppe. In the absence of a strong direct CO2 fertilization effect on plant growth (e.g., due to nutrient limitation), water stress or decreased carbon gain from higher autotrophic respiration results in decreased productivity and loss of forest cover.

Poulter, B.; Pederson, N.; Liu, H.; Zhu, Z.; D'Arrigo, R.; Ciais, P.; Davi, N.; Frank, D. C.; Leland, C.; Myneni, R.; Piao, S.; Wang, T.

2012-12-01

178

Lattice spacing dependence of phase transition temperature in the classical linear sigma model  

E-print Network

We have investigated the phase transition properties of classical linear sigma model. The fields were kept in contact with a heat bath for sufficiently long time such that fields are equilibrated at the temperature of the heat bath. It was shown that the sigma model fields undergoes phase transition, but the transition temperature depend crucially on the lattice spacing. In the continuum limit, the transition temperature tends to zero or at least to a very low value.

A. K. Chaudhuri

2001-05-02

179

Problems with solar, volcanic, and ENSO attribution using multiple linear regression methods on temperatures from 1979-2012  

NASA Astrophysics Data System (ADS)

The effectiveness of multiple linear regression approaches in removing solar, volcanic, and El Nino Southern Oscillation (ENSO) influences from the recent (1979-2012) surface temperature record is examined, using simple energy balance and global climate models (GCMs). These multiple regression methods are found to incorrectly diagnose the underlying signal - particularly in the presence of a deceleration - by generally overestimating the solar cooling contribution to an early 21st century pause while underestimating the warming contribution from the Mt. Pinatubo recovery. In fact, one-box models and GCMs suggest that the Pinatubo recovery has contributed more to post-2000 warming trends than the solar minimum has contributed to cooling over the same period. After adjusting the observed surface temperature record based on the natural-only multi-model mean from several CMIP5 GCMs and an empirical ENSO adjustment, a significant deceleration in the surface temperature increase is found, ranging in magnitude from -0.06 to -0.12 K dec-2 depending on model sensitivity and the temperature index used. This likely points to internal decadal variability beyond these solar, volcanic, and ENSO influences.

Masters, T.

2013-11-01

180

Design of high power LD soft-switching linear drive power supply and temperature controller  

Microsoft Academic Search

In order to drive linear high-power laser diode, we design a new-style and high-efficiency linear power supply and the temperature controlling system, achieving a high-stability current output from 0 to 6 A, whose current ripple is less than 1%. Innovative design of the rectifier mode switch circuit, voltage feedback networks, the soft-switch anti-surge filter circuit and over-current protection circuits with

Min Zhou; Aiwen Zhang; Zhiping Cai; Huiying Xu; Yang Liu; Manli Li

2008-01-01

181

Methodology and results of calculating central California surface temperature trends: Evidence of human-induced climate change?  

USGS Publications Warehouse

A procedure is described to construct time series of regional surface temperatures and is then applied to interior central California stations to test the hypothesis that century-scale trend differences between irrigated and nonirrigated regions may be identified. The procedure requires documentation of every point in time at which a discontinuity in a station record may have occurred through (a) the examination of metadata forms (e.g., station moves) and (b) simple statistical tests. From this "homogeneous segments" of temperature records for each station are defined. Biases are determined for each segment relative to all others through a method employing mathematical graph theory. The debiased segments are then merged, forming a complete regional time series. Time series of daily maximum and minimum temperatures for stations in the irrigated San Joaquin Valley (Valley) and nearby nonirrigated Sierra Nevada (Sierra) were generated for 1910-2003. Results show that twentieth-century Valley minimum temperatures are warming at a highly significant rate in all seasons, being greatest in summer and fall (> +0.25??C decade-1). The Valley trend of annual mean temperatures is +0.07?? ?? 0.07??C decade-1. Sierra summer and fall minimum temperatures appear to be cooling, but at a less significant rate, while the trend of annual mean Sierra temperatures is an unremarkable -0.02?? ?? 0.10??C decade-1. A working hypothesis is that the relative positive trends in Valley minus Sierra minima (>0.4??C decade-1 for summer and fall) are related to the altered surface environment brought about by the growth of irrigated agriculture, essentially changing a high-albedo desert into a darker, moister, vegetated plain. ?? 2006 American Meteorological Society.

Christy, J.R.; Norris, W.B.; Redmond, K.; Gallo, K.P.

2006-01-01

182

Investigation of sea level anomalies related with NAO along the west coasts of Turkey and their consistency with sea surface temperature trends  

NASA Astrophysics Data System (ADS)

It is well-known that North Atlantic Oscillation (NAO), which is one of the large-scaled climate modes effective in the Northern Hemisphere, has a considerable affect on the water resources and climatic indicators especially in the Mediterranean basin. In recent years, also crucial studies about the sea level rise in relation to climate change have been accelerated. Turkey has about 20 modernized tide gauge stations equipped with permanent GPS receivers and targets to contribute to global sea level rise studies in the future. The aim of this study is to find out the effects of North Atlantic Oscillation on the national shores using the data of four tide-gauge stations located on the Aegean and Mediterranean coasts of Turkey. Implications from these four tide gauges would motivate researches to take into account the effect of NAO in calculating the true sea level rise at the national coasts. While studying the sea level changes, vertical crustal movement has been observed using the data of tide gauge GPS stations, and this situation has been taken into consideration in the evaluation of sea levels. Besides, in order to investigate the influences of thermal expansion on sea levels, sea surface temperature data of the meteorology stations near the tide gauges have been evaluated. The homogeneity of the data sets was analyzed using four statistical tests. As a result, all of the meteorology stations' temperature series and tide gauges' data are subjected to trend detection after the homogeneity analysis. Eventually, the effects of North Atlantic Oscillation on both sea levels and sea surface temperatures have been introduced. The study results indicate high correlation between North Atlantic Oscillation and the sea level and sea surface temperature events. It is seen that the linear correlation between the sea level trends of the considered stations and the sea surface temperature data of the related meteorology stations is considerably significant.

Dogan, Mustafa; Cigizoglu, H. Kerem; Sanli, D. Ugur; Ulke, Asli

2014-08-01

183

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

184

Heating processes in plasmonic resonances: a non-linear temperature dependent permittivity model  

NASA Astrophysics Data System (ADS)

Heating processes in plasmonics are essential every time the interaction with electromagnetic fields induces dissipation within metallic nanostructures. In particular the capability to predict the final temperature reached by a system (e.g. an ensemble of nanoparticles within a host medium) can be crucial when dealing with electronic, medical or chemical applications. Here we present a dispersive model of the dielectric function of a metallic medium which depends on temperature. Since temperature, in turn, depends on the intensity of the electromagnetic source and on the optical response of the medium itself, the model expresses non-linearity features. The model, which does not require any fitting parameter, can be utilized whenever the impact of temperature on the optical response of a system needs to be clarified and/ or when non-linearities might play a major role.

Alabastri, Alessandro; De Angelis, Francesco; Proietti Zaccaria, Remo

2014-09-01

185

Infrared line cameras based on linear arrays for industrial temperature measurement  

Microsoft Academic Search

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

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

2002-01-01

186

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

187

Comparing linear ion-temperature-gradient-driven mode stability of the National Compact Stellarator Experiment and a shaped tokamak  

E-print Network

Comparing linear ion-temperature-gradient-driven mode stability of the National Compact Stellarator by a variational principle Phys. Plasmas 20, 024504 (2013) Ion temperature gradient instability at sub://pop.aip.org/about/rights_and_permissions #12;Comparing linear ion-temperature-gradient-driven mode stability of the National Compact

Hammett, Greg

188

Continuous salinity and temperature data from san francisco estuary, 19822002: Trends and the salinity-freshwater inflow relationship  

USGS Publications Warehouse

The U.S. Geological Survey and other federal and state agencies have been collecting continuous temperature and salinity data, two critical estuarine habitat variables, throughout San Francisco estuary for over two decades. Although this dynamic, highly variable system has been well studied, many questions remain relating to the effects of freshwater inflow and other physical and biological linkages. This study examines up to 20 years of publically available, continuous temperature and salinity data from 10 different San Francisco Bay stations to identify trends in temperature and salinity and quantify the salinityfreshwater inflow relationship. Several trends in the salinity and temperature records were identified, although the high degree of daily and interannual variability confounds the analysis. In addition, freshwater inflow to the estuary has a range of effects on salinity from -0.0020 to -0.0096 (m3 s-1) -1 discharge, depending on location in the estuary and the timescale of analyzed data. Finally, we documented that changes in freshwater inflow to the estuary that are within the range of typical management actions can affect bay-wide salinities by 0.61.4. This study reinforces the idea that multidecadal records are needed to identify trends from decadal changes in water management and climate and, therefore, are extremely valuable. ?? 2011 Coastal Education & Research Foundation.

Shellenbarger, G.G.; Schoellhamer, D.H.

2011-01-01

189

Linear metric and temperature fluctuations of a charged plasma in a primordial magnetic field  

E-print Network

We discuss tensor metric perturbations in a magnetic field around the homogeneous Juttner equilibrium of massless particles in an expanding universe. We solve the Liouville equation and derive the energy-momentum tensor up to linear terms in the metric and in the magnetic field.The term linear in the magnetic field is different from zero if the total charge of the primordial plasma is non-zero. We obtain an analytic formula for temperature fluctuations treating the tensor metric perturbations and the magnetic field as independent random variables. Assuming a cutoff on large momenta of the magnetic spectral function we show that the presence of the magnetic field can discriminate only low multipoles in the multipole expansion of temperature fluctuations. In such a case the term linear in the magnetic field can be more important than the quadratic one (corresponding to the fluctuations of the pure magnetic field).

Haba, Z

2015-01-01

190

Linear metric and temperature fluctuations of a charged plasma in a primordial magnetic field  

E-print Network

We discuss tensor metric perturbations in a magnetic field around the homogeneous Juttner equilibrium of massless particles in an expanding universe. We solve the Liouville equation and derive the energy-momentum tensor up to linear terms in the metric and in the magnetic field.The term linear in the magnetic field is different from zero if the total charge of the primordial plasma is non-zero. We obtain an analytic formula for temperature fluctuations treating the tensor metric perturbations and the magnetic field as independent random variables. Assuming a cutoff on large momenta of the magnetic spectral function we show that the presence of the magnetic field can discriminate only low multipoles in the multipole expansion of temperature fluctuations. In such a case the term linear in the magnetic field can be more important than the quadratic one (corresponding to the fluctuations of the pure magnetic field).

Z. Haba

2015-04-14

191

Test on opto couplers in the linear application considering temperature, radiation and Vce effects  

Microsoft Academic Search

The test result for four different types of opto couplers (20 devices each) operating at very low current levels (lower than the test condition for logic operation) considering temperature, radiation and absolute value of forward voltage (Vce) effects are presented. A galvanically isolated precision linear interface using a pair of opto couplers is introduced, which could be of interest in

H. Spruijt; K. Burrows; J. Andersen; S. Marsden; J. Tilmant

1991-01-01

192

Kaon condensation in the linear sigma model at finite density and temperature  

SciTech Connect

Basing on the Cornwall-Jackiw-Tomboulis effective action approach we formulate a theoretical formalism for studying kaon condensation in the linear sigma model at finite density and temperature. We derive the renormalized effective potential in the Hartree-Fock approximation, which preserves the Goldstone theorem. This quantity is then used to consider physical properties of kaon matter.

Tran Huu Phat [Vietnam Atomic Energy Commission, 59 Ly Thuong Kiet, Hanoi (Viet Nam); Dong Do University, 8 Nguyen Cong Hoan, Hanoi (Viet Nam); Nguyen Van Long [Gialai Teacher College, 126 Le Thanh Ton, Pleiku, Gialai (Viet Nam); Nguyen Tuan Anh [Institute for Nuclear Science and Technique, 5T-160 Hoang Quoc Viet, Hanoi (Viet Nam); Le Viet Hoa [Hanoi National University of Education, 136 Xuan Thuy, Cau Giay, Hanoi (Viet Nam)

2008-11-15

193

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

194

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, César R.; Bowers, M. Deane; Guralnick, Robert P.

2012-01-01

195

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

196

A piecewise linear model for detecting climatic trends and their structural changes with application to mesosphere/lower thermosphere winds over Collm, Germany  

NASA Astrophysics Data System (ADS)

A piecewise linear model is developed to detect climatic trends and their structural changes in time series with a priori unknown number and positions of breakpoints (BPs). The departure (i.e., the initial noise term) of trends from time series is allowed to be interpreted by the first- and second-order autoregressive models. The goodness of fit of candidate models, if the residuals are accepted as normally distributed white noise, is evaluated using the Schwarz Bayesian Information Criterion (BIC). The uncertainties of all trend parameters are estimated using the Monte-Carlo method. The model is applied to the mesosphere and lower thermosphere (MLT) winds obtained at Collm, Germany, during 1960-2007. A persistent increase after ˜1980 of the zonal prevailing wind is observed in all seasons and hence in the zonal annual mean based on the primary models. Trends of the meridional prevailing wind are different for different seasons. Several major trend BPs are identified in the annual mean zonal and meridional winds according to BIC. However, in view of the large wind variability before the late 1970s, alternative models are considered. This provides four additional minor breaks. In some cases, the initial noise must be further interpreted by autoregressive models, suggesting that other unidentified factors may also play a role.

Liu, R. Q.; Jacobi, Ch.; Hoffmann, P.; Stober, G.; Merzlyakov, E. G.

2010-11-01

197

Split Stirling linear cryogenic cooler for a new generation of high temperature infrared imagers  

NASA Astrophysics Data System (ADS)

Split linear cryocoolers find use in a variety of infrared equipment installed in airborne, heliborne, marine and vehicular platforms along with hand held and ground fixed applications. An upcoming generation of portable, high-definition night vision imagers will rely on the high-temperature infrared detectors, operating at elevated temperatures, ranging from 95K to 200K, while being able to show the performance indices comparable with these of their traditional 77K competitors. Recent technological advances in industrial development of such high-temperature detectors initialized attempts for developing compact split Stirling linear cryogenic coolers. Their known advantages, as compared to the rotary integral coolers, are superior flexibility in the system packaging, constant and relatively high driving frequency, lower wideband vibration export, unsurpassed reliability and aural stealth. Unfortunately, such off-the-shelf available linear cryogenic coolers still cannot compete with rotary integral rivals in terms of size, weight and power consumption. Ricor developed the smallest in the range, 1W@95K, linear split Stirling cryogenic cooler for demanding infrared applications, where power consumption, compactness, vibration, aural noise and ownership costs are of concern.

Veprik, A.; Zechtzer, S.; Pundak, N.

2010-04-01

198

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

Research, Inc., Cambridge April 22, 1997 Abstract Given the presence of a meridional temperature gradientTrends in the Surface Meridional Temperature Gradient Alix I. Gitelman a , James S. Risbey b --- i.e. the meridional temperature gradient (MTG) --- measures the difference in temperature between

199

Temperature Trends in the Upper Troposphere to Lower Stratosphere from Radio Occultation Climate Records 2002 to 2012  

NASA Astrophysics Data System (ADS)

Atmospheric climate monitoring and change detection requires observations of high quality. Conventional observations are available from weather satellites and balloons which were originally not intended to serve climate monitoring needs. The construction of climate records from these data necessitates demanding homogenization and calibration processes. During the last years intensive efforts have been put into reconciling differences in atmospheric temperature trends from radiosondes, microwave sounding instruments, and climate model data. Though basic agreement confirmed a tropospheric warming and stratospheric cooling, the uncertainties in the trends and their vertical structure remain large in the upper troposphere and lower stratosphere (UTLS). A relatively new atmospheric record is available from radio occultation (RO) observations based on signals of the Global Positioning System (GPS), providing a global and continuous data set of key climate variables for the UTLS since fall 2001. The measurements are based on precise atomic clocks and feature accuracy, long-term stability, and consistency across RO missions. Due to this consistency RO measurements from different satellites can be combined without intercalibration. Profiles of bending angle, refractivity, pressure, geopotential height, and temperature are retrieved at a high vertical resolution of about 0.5 km to 1.5 km in the UTLS. Best data quality is achieved from about 5 km to 30 km altitude. Due to these characteristics RO qualifies as climate benchmark data type to investigate atmospheric climate change. In this study we use the recently reprocessed RO data record of the Wegener Center (University of Graz, Austria) over the period 2002 to 2012, including data from the CHAMP, GRACE, Formosat-3/COSMIC, and MetOp satellites. We first briefly recall the demonstrated and remarkable utility of RO for UTLS climate monitoring and then focus on temperature trends in the tropical UTLS. Vertically resolved temperature anomalies and trends will be presented and compared to those of recent radiosonde records and global climate models. In addition, layer average temperatures of the Advanced Microwave Sounding Unit (AMSU) and the Stratospheric Sounding Unit (SSU) will be compared for the lower- to mid-stratosphere channels. Overall we aim at providing deeper insight into recent anomalies and trends in the tropical UTLS based on the RO reference climate record.

Steiner, A. K.; Scherllin-Pirscher, B.; Ladstaedter, F.; Schwaerz, M.; Rieckh, T. M.; Kirchengast, G.

2013-12-01

200

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

201

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

202

Trends and variability in the sea surface height, sea surface temperature and wind stress curl in the South Atlantic ocean  

NASA Astrophysics Data System (ADS)

Altimetry sea level anomalies (SLA), sea surface temperatures anomalies (SSTA) and wind stress curl (WSC) were analyzed and had their trends calculated and their variability studied for the South Atlantic ocean using the last 19 years of SALTO/DUACS altimeter data, ERSST data and ERA-INTERIM data. All data had their temporal resolution adjusted to the one of altimeter data. The trends were calculated between January, 1st 1993 and December, 31th 2011. The stronger and positive SLA trends occurred in the region of the Zapiola Ridge (14 mm/year) and in some places in the Drake Passage (10 mm/year). Negative trends were observed in the Southern part of Argentinian basin (-4 mm/year), next to the Confluence Brazil Malvinas (-8 mm/year) and to the southwest of the African coast (-6 mm/year). The SST trends were positive North of 40°S, and negative south of 60°S. They were also negative along the Argentinean continental slope along the path of the Malvinas Current. The WSC trend was also negative along the Argentine continental slope. In the Southeast Atlantic, the WSC trend had a zonal distribution with alternate signs. To understand the processes responsible for the trend patterns in the South Atlantic ocean, the high and the low frequencies were obtained applying successively a 25 week band pass filter followed by a 37 week band pass filter. The percentage of explained variance by the high frequency, low frequency and seasonal signals (hf/lf/ss) were compared for SLA, SSTA and WSC. The variance of SLA in the Southwestern Atlantic was explained by the proportion of (80%, 15%,5%), except along the Argentinean continental slope (15%, 50%, 35%), the inner part of the ZR (10%,65%,25%). The central part of the South Atlantic showed dominant low frequency variance (proportions of 15%, 80% and 5% (hf/lf/ss), respectively). The SSTA variance was dominated by the high frequency in the Uruguayan coast, around ZR, in the Drake Passage and in the Agulhas Leakage (60-80%), low frequency variability responds to 55-75% of the total variability away from the continental borders. The seasonal frequency is important in the CBM region and in the inner of ZR (25%, 40%, 35%). The WSC variance was mostly explained by high frequencies (70%), low frequencies explained between 10% and 15%, at latitudes lower than 20°S, in the Argentinean continental slope and in the Agulhas Leakage. The EOF analysis were performed on the high and low frequencies components of each variable. The results will be presented in the poster.

Porto da Silveira, Isabel; Ponzi Pezzi, Luciano; Buss de Souza, Ronald; Sennéchael, Nathalie; Provost, Christine

2013-04-01

203

Snowmelt timing (onset and melt-refreeze) trends in the Yukon River basin determined from passive microwave brightness temperatures  

NASA Astrophysics Data System (ADS)

High latitude drainage basins are experiencing increases in temperature higher than the global average with snowmelt dominated basins most sensitive to effects in winter due to snowpack's integration of these changes over the season. This may influence the timing of snowmelt onset and the occurrence of any preceding (early) melt events, resulting in changes in spring runoff and associated flooding, often the most significant hydrologic events of the year. It is therefore critical to be able to understand and model these processes, especially for ungauged basins with little meteorological data. For such basins, passive microwave remote sensing can be utilized; an approach tested in the Yukon River Basin draining more than 850,000 km2 of Alaska and the Yukon Territory. Brightness temperature (Tb) data from the Advanced Microwave Scanning Radiometer for EOS (AMSR-E) 36.5 V-GHz frequency and the Special Sensor Microwave Imager (SSM/I) 37 V-GHz frequency together form a time series from 1988 to 2010, enabling us to detect trends in snowmelt onset timing and the end of melt-refreeze period. Tb encompasses both physical temperature and emissivity with wet snow easily detected by an abrupt increase in emissivity. Tb and diurnal amplitude variation (DAV) thresholds determine dates of melt onset and melt-freeze end (end of high DAV), defined as where thresholds are met for more than three of five consecutive days. Melt that is detected before melt onset and is not sustained for more than three out of five days is classified as an early melt event. Preliminary results of trends in snowmelt onset and occurrence of early melt events suggest sub-basin differences occur with varying landcover, permafrost, and elevation. Of the thirteen sub-basins that comprise the Yukon River basin, five have significant trends toward later melt onset dates, while the northernmost (the Chandalar and Porcupine) have earlier melt onset. The majority of basins with later onset show increasing trends of early melt events, while those with earlier onset have decreasing trends, suggesting winter melt dynamics may affect melt onset later in the year. Significant variability, however, requires further analysis to more definitively determine trends and relationships between the melt parameters.

Semmens, K. A.; Ramage, J. M.

2011-12-01

204

Impact of land use and precipitation changes on surface temperature trends in Argentina  

Microsoft Academic Search

The “observation minus reanalysis” (OMR) method has been used to estimate the impact of changes in land use (including urbanization and agricultural practices such as irrigation) by computing the difference between the trends of the surface observations (which reflect all the sources of climate forcing, including surface effects) and the NCEP\\/NCAR reanalysis (which only contains the forcings influencing the assimilated

Mario N. Nuñez; Héctor H. Ciapessoni; Alfredo Rolla; Eugenia Kalnay; Ming Cai

2008-01-01

205

Impact of land use and precipitation changes on surface temperature trends in Argentina  

Microsoft Academic Search

The ``observation minus reanalysis'' (OMR) method has been used to estimate the impact of changes in land use (including urbanization and agricultural practices such as irrigation) by computing the difference between the trends of the surface observations (which reflect all the sources of climate forcing, including surface effects) and the NCEP\\/NCAR reanalysis (which only contains the forcings influencing the assimilated

Mario N. Nuñez; Héctor H. Ciapessoni; Alfredo Rolla; Eugenia Kalnay; Ming Cai

2008-01-01

206

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

207

High-Tc superconductivity originated from strong spin-charge correlation: indication from linear temperature dependence of resistivity  

E-print Network

Both the highest- and the linear temperature dependence of the resistivity in wide temperature range appear at the optimally doped regions of Cu-based superconductors1,2,3,4,5, and the highest- of Fe-based superconductors6,7 are also associated with the linear temperature dependence of the resistivity in normal states near superconducting states. This means that the high temperature superconductivity and the linear temperature dependence of the resistivity should be dominated by the same mechanism. This letter on theoretic calculation clearly shows that strong spin-charge correlation dominated resistivity behaves the linear temperature dependence, thus high-temperature superconductivity should be induced by strong spin-charge correlation.

Tian De Cao

2009-05-05

208

The linear temperature dependence of the paramagnetic resonance linewidth in the manganate perovskites ? and ?  

Microsoft Academic Search

The temperature dependence of the static magnetic susceptibility 0953-8984\\/8\\/50\\/048\\/img9 (5 to 700 K) and that of the electron paramagnetic resonance linewidth 0953-8984\\/8\\/50\\/048\\/img10 (300 to 700 K) measured at 9.25 GHz is reported for bulk polycrystalline samples of 0953-8984\\/8\\/50\\/048\\/img11 and 0953-8984\\/8\\/50\\/048\\/img12 with negative giant magnetoresistance. For both systems, 0953-8984\\/8\\/50\\/048\\/img10 and the product 0953-8984\\/8\\/50\\/048\\/img14 increase linearly with temperature above 0953-8984\\/8\\/50\\/048\\/img15. Following the

Mohindar S. Seehra; Manjula M. Ibrahim; V. Suresh Babu; G. Srinivasan

1996-01-01

209

Recent Trends in Permafrost Temperature From North American Sites Contributing to the Global Terrestrial Network for Permafrost  

NASA Astrophysics Data System (ADS)

The Global Terrestrial Network for Permafrost (GTN-P) was established in 1999 to provide long-term field observations of active layer and permafrost thermal state that are required to determine the present permafrost conditions and to detect changes in permafrost stability. The data supplied by this network enhances our ability to predict the consequences of permafrost degradation associated with climate warming and to develop adaptation strategies to respond to these changes. The GTN-P contributes to the World Meteorological Organization's Global Climate Observing System and Global Terrestrial Observing System. This paper focuses on the thermal monitoring component of the GTN-P. To date, over 300 thermal monitoring sites have been identified from 16 countries for inclusion in the GTN-P. Site descriptions (metadata) and summary data are disseminated through the GTN-P web site (www.gtnp.org). Plans are being developed for a GTN-P contribution to the International Polar Year which will involve a collection of data from all monitoring sites if possible in 2006 and 2007. This paper reports initial results from North American sites. The results show that although recent warming of permafrost has been observed across the North American permafrost zone, the magnitude and timing of this warming varies. For example, warming has been observed since the early to mid 1980s in the western North American Arctic. Warming however in the Canadian eastern and high Arctic occurred in the late 1990s with cooler permafrost temperature generally occurring in the 1980s and early 1990s. These trends in permafrost temperature are consistent with air temperature trends observed since the 1970s in the Canadian Arctic. Variability in snow cover especially in the high Arctic, is also an important factor influencing the spatial and temporal trends in permafrost temperature.

Smith, S.; Burgess, M.; Romanovsky, V.; Clow, G.; Brown, J.

2004-05-01

210

Long-term trends of biogenic sulfur aerosol and its relationship with sea surface temperature in Arctic Finland  

NASA Astrophysics Data System (ADS)

years of week-long total suspended particle samples from Kevo Finland were analyzed for methane sulfonic acid (MSA) and sulfate. Kevo is located 350 km north of the Arctic Circle. MSA and non-sea-salt sulfate (NSS-SO4) showed clear seasonal trends. MSA peaks from May to July, coinciding with warmer waters and increased biogenic activity in the surrounding seas. NSS-SO4 peaks in March with a minimum during the summer, the typical pattern for Arctic haze. MSA concentrations were found to be positively correlated (p < 0.001) with sea surface temperature anomalies in the surrounding seas. MSA showed a trend of 0.405 ng/m3/yr (0.680%/yr) for June and July. NSS-SO4 concentrations at Kevo declined dramatically in the early 1990s, probably as a result of the collapse of the Soviet Union. The decline has continued since the mid-1990s.

Laing, James R.; Hopke, Philip K.; Hopke, Eleanor F.; Husain, Liaquat; Dutkiewicz, Vincent A.; Paatero, Jussi; Viisanen, Yrjö

2013-10-01

211

Global trends in lake surface temperatures observed using multi-sensor thermal infrared imagery  

Microsoft Academic Search

Recent research has shown that the temperature of lakes and other inland water bodies does not only act as a good indicator of climate variability but under certain conditions can even increase more rapidly than the regional air temperature. Further investigation of this phenomenon in particular and of the interaction between lake temperature and climate variability in general requires extensive

Philipp Schneider; Simon J. Hook; Robert G. Radocinski; Gary K. Corlett; Glynn C. Hulley; S. Geoffrey Schladow; Todd E. Steissberg

2010-01-01

212

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

213

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.

214

Factors contributing to diurnal temperature range trends in twentieth and twenty-first century simulations of the CCCma coupled model  

NASA Astrophysics Data System (ADS)

Trends in the diurnal temperature range (DTR) are examined in the late twentieth and the twenty-first centuries in a coupled climate model representing the atmosphere, ocean, sea ice, and land surface systems. Consistent with past studies, the DTR decreases during this time. These decreases are concentrated in middle latitudes, with much smaller changes occurring in the low latitudes. Strong seasonal characteristics to this pattern exist, although these are different in either hemisphere. In the model integrations, variations in the DTR are much more sensitive to changes in feedbacks than in direct forcings. The DTR is found to be insensitive to the scattering of sunlight by sulfate aerosols and the increased mean temperature. Instead, variations in the DTR arise mostly from changes in clouds and in soil moisture. Consequently, the decreasing trends stem from increases in the reflection of solar radiation by clouds moderated by decreases in soil moisture, mostly through its effect on the ground heat capacity. Both factors contribute about equally to the DTR trend. The exception to this relation occurs in the middle latitudes during winter, when snow cover reduces the influence of changes in solar radiation and soil moisture. Decreases during this season are a consequence of the artificial tendency in the model for the DTR to be very small when the mean temperature is near the freezing point. While the accuracy of these conclusions depends upon the model's ability to represent the relevant processes, the results highlight the importance of clouds and land surface processes to the DTR and its long-term change. The importance of soil moisture found here implies that changes in the physiological response of vegetation and in land use could have important effects on the DTR.

Stone, D. A.; Weaver, A. J.

2002-11-01

215

Non-Markovian Quantum State Diffusion for temperature-dependent linear spectra of light harvesting aggregates.  

PubMed

Non-Markovian Quantum State Diffusion (NMQSD) has turned out to be an efficient method to calculate excitonic properties of aggregates composed of organic chromophores, taking into account the coupling of electronic transitions to vibrational modes of the chromophores. NMQSD is an open quantum system approach that incorporates environmental degrees of freedom (the vibrations in our case) in a stochastic way. We show in this paper that for linear optical spectra (absorption, circular dichroism), no stochastics is needed, even for finite temperatures. Thus, the spectra can be obtained by propagating a single trajectory. To this end, we map a finite temperature environment to the zero temperature case using the so-called thermofield method. The resulting equations can then be solved efficiently by standard integrators. PMID:25612697

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

2015-01-21

216

Non-Markovian Quantum State Diffusion for temperature-dependent linear spectra of light harvesting aggregates  

NASA Astrophysics Data System (ADS)

Non-Markovian Quantum State Diffusion (NMQSD) has turned out to be an efficient method to calculate excitonic properties of aggregates composed of organic chromophores, taking into account the coupling of electronic transitions to vibrational modes of the chromophores. NMQSD is an open quantum system approach that incorporates environmental degrees of freedom (the vibrations in our case) in a stochastic way. We show in this paper that for linear optical spectra (absorption, circular dichroism), no stochastics is needed, even for finite temperatures. Thus, the spectra can be obtained by propagating a single trajectory. To this end, we map a finite temperature environment to the zero temperature case using the so-called thermofield method. The resulting equations can then be solved efficiently by standard integrators.

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

2015-01-01

217

Linear temperature dependence of the electric-quadrupole interaction at /sup 181/Ta impurities in lutetium  

SciTech Connect

The electric-quadrupole hyperfine interaction at dilute tantalum impurities in lutetium metal has been measured between 10 and 655 K using time-differential perturbed angular correlations of the 133--482-keV cascade in /sup 181/Ta. The temperature dependence of the quadrupole frequency is described by the linear temperature relation n/sub Q/(T) = )338.7(11)(1-4.05(14) x 10/sup -4/T)) MHz. This result contradicts the assumptions of the phenomenological model for interaction between open 4f-orbital hosts and dilute closed-shell impurities previously proposed by the authors, whereby the system LuTa should exhibit the usual T/sup 1.5/ temperature dependence. The effect on closed-shell probes of the crystal-field-induced quadrupolar distortion of open-orbital host ions, if present at all, is much more complex than previously assumed.

Rasera, R.L.; Dunlap, B.D.; Shenoy, G.K.

1981-04-01

218

Linear temperature dependence of the electric-quadrupole interaction at 181Ta impurities in lutetium  

NASA Astrophysics Data System (ADS)

The electric-quadrupole hyperfine interaction at dilute tantalum impurities in lutetium metal has been measured between 10 and 655 K using time-differential perturbed angular correlations of the 133-482-keV cascade in 181Ta. The temperature dependence of the quadrupole frequency is described by the linear temperature relation ?Q(T)={338.7(11)[1-4.05(14)×10-4T]} MHz. This result contradicts the assumptions of the phenomenological model for interaction between open 4f-orbital hosts and dilute closed-shell impurities previously proposed by the authors, whereby the system LuTa should exhibit the usual T1.5 temperature dependence. The effect on closed-shell probes of the crystal-field-induced quadrupolar distortion of open-orbital host ions, if present at all, is much more complex than previously assumed.

Rasera, R. L.; Dunlap, B. D.; Shenoy, G. K.

1981-04-01

219

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 efficient method to calculate excitonic properties of aggregates composed of organic chromophores, taking into account the coupling of electronic transitions to vibrational modes of the chromophores. NMQSD is an open quantum system approach that incorporates environmental degrees of freedom (the vibrations in our case) in a stochastic way. We show in this paper that for linear optical spectra (absorption, circular dichroism) no stochastics is needed, even for finite temperatures. Thus, the spectra can be obtained by propagating a single trajectory. To this end we map a finite temperature environment to the zero temperature case using the so-called thermofield method. The resulting equations can then be solved efficiently by standard integrators.

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

2014-12-18

220

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

221

Split Stirling linear cryogenic cooler for high-temperature infrared sensors  

NASA Astrophysics Data System (ADS)

Infrared imagers play a vital role in the modern tactics of carrying out surveillance, reconnaissance, targeting and navigation operations. The cooled systems are known to be superior to their uncooled competitors in terms of working ranges, resolution and ability to distinguish/track fast moving objects in dynamic infrared scenes. These advantages are primarily due to maintaining the infrared focal plane arrays at cryogenic temperatures using mechanical closed cycle Stirling cryogenic coolers. Recent technological advances in industrial application of high-temperature (up to 200K) infrared detectors has spurred the development of linearly driven microminiature split Stirling cryogenic coolers having inherently longer life spans, lower vibration export and better aural stealth as compared to their rotary driven rivals. Moreover, recent progress in designing highly efficient "moving magnet" resonant linear actuators and dedicated smart electronics have enabled further improvements to the cooler size, weight, power consumption, cooldown time and ownership costs. The authors report on the development and project status of a novel microminiature split Stirling linear cryogenic cooler having a shortened to 19mm cold finger and a high driving frequency (90Hz). The cooler has been specifically designed for cooling 130K infrared sensors of future portable infrared imagers, where compactness, low steady-state power consumption and fast cool-down time are of primary concern.

Veprik, A.; Zehter, S.; Vilenchik, H.; Pundak, N.

2009-05-01

222

Diurnal temperature range and cloud cover in the Nordic countries: observed trends and estimates for the future  

NASA Astrophysics Data System (ADS)

A simple regression model relating local monthly mean diurnal temperature range (DTR) and cloudiness at 10 synoptic stations in the Nordic region to monthly mean large-scale tropospheric flow has been constructed. The tropospheric flow data, which is input to the model, includes both 500 hPa height and 500/1000 hPa thickness fields which are compressed via an EOF-technique. The regression coefficients are calculated from a 27 year record of analysed flow and locally observed DTR and cloudiness. The regression model has been used to down-scale the large-scale flow produced in a CO 2 sensitivity experiment with a coupled ocean-atmosphere climate model (ECHAM-1). The down-scaled "high CO 2" DTR is generally smaller than found when down-scaling the corresponding climate model control experiment. The opposite statement applies to cloudiness. DTR-anomalies of the order 2 Kelvin (K) are obtained in the central/northern parts of Fenno-Scandia in the middle of the 21st century while anomalies much closer to zero are found over the Iceland/Southern Greenland region. Consistent with this picture the cloudiness anomalies in the high CO 2 case are predicted highest near the central/northern parts of Fenno-Scandia. The results presented here indicate that periods observed to be anomalously warm on a large-scale — corresponding to high CO 2 concentrations — are also observed to be more cloudy and it is argued that clouds may have a thermostatic effect. We have calculated DTR and cloud cover trends at the 10 stations used in the regression model in order to assess if they are consistent with the predicted estimates and as such reflect a forcing of the climate system. We find that none of the stations show DTR/cloud cover trends significantly different from zero in the period 1961-1987. We do, however, see a negative DTR trend and a positive cloud trend when we consider a slightly longer time series (1950-1992) at Reykjavik. All statements about trends are, however, very uncertain because the observed records in addition to any trends reflect a large natural variability on decadal time scales as well as possible observational inhomogeneities.

Kaas, E.; Frich, P.

223

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

224

Linear and nonlinear dynamics of electron temperature gradient mode in non-Maxwellian plasmas  

SciTech Connect

The effect of non-Maxwellian distributed ions on electron temperature gradient mode is investigated. The linear dispersion relation of ?{sub e}?mode is obtained which shows that the behavior of this mode changes in the presence of superthermal ions. The growth rate of ?{sub e}?mode driven linear instability is found and is observed to modify due to nonthermal ions. However, it is found that this leaves the electron energy transport coefficient unchanged. In the nonlinear regime, a dipolar vortex solution is derived which indicates that the dynamic behavior of the vortices changes with the inclusion of kappa distributed ions. The importance of present study with respect to space and laboratory plasmas is also pointed out.

Zakir, U.; Qamar, A. [Institute of Physics and Electronics, University of Peshawar, Peshawar (Pakistan)] [Institute of Physics and Electronics, University of Peshawar, Peshawar (Pakistan); Haque, Q. [Theoretical Plasma Physics Division, PINSTECH, Islamabad (Pakistan) [Theoretical Plasma Physics Division, PINSTECH, Islamabad (Pakistan); National Centre for Physics, Islamabad (Pakistan)

2013-05-15

225

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

226

Solar Wind Proton Temperature Anisotropy: Linear Theory and WIND/SWE Observations  

NASA Technical Reports Server (NTRS)

We present a comparison between WIND/SWE observations (Kasper et al., 2006) of beta parallel to p and T perpendicular to p/T parallel to p (where beta parallel to p is the proton parallel beta and T perpendicular to p and T parallel to p are the perpendicular and parallel proton are the perpendicular and parallel proton temperatures, respectively; here parallel and perpendicular indicate directions with respect to the ambient magnetic field) and predictions of the Vlasov linear theory. In the slow solar wind, the observed proton temperature anisotropy seems to be constrained by oblique instabilities, by the mirror one and the oblique fire hose, contrary to the results of the linear theory which predicts a dominance of the proton cyclotron instability and the parallel fire hose. The fast solar wind core protons exhibit an anticorrelation between beta parallel to c and T perpendicular to c/T parallel to c (where beta parallel to c is the core proton parallel beta and T perpendicular to c and T parallel to c are the perpendicular and parallel core proton temperatures, respectively) similar to that observed in the HELIOS data (Marsch et al., 2004).

Hellinger, P.; Travnicek, P.; Kasper, J. C.; Lazarus, A. J.

2006-01-01

227

The application of boundary element evaluation on a silencer in the presence of a linear temperature gradient  

Microsoft Academic Search

A boundary element method for analyzing the acoustic performance of a muffler in the presence of a linear temperature gradient is developed. In order to simulate the temperature gradient, the muffler is divided into segments with different constant temperatures. The boundary element approach is applied to each sub-volume to establish the relationship between pressure and its gradient on the surface.

Chao-Nan Wang; Yih-Nan Chen; Jean-Yih Tsai

2001-01-01

228

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

229

Operating Temperature Trends in Amorphous In–Ga–Zn–O Thin-Film Transistors  

Microsoft Academic Search

The electrical performance as a function of operating temperature of amorphous indium gallium zinc oxide (a-IGZO) thin-film transistors (TFTs) is assessed by measuring drain current versus gate voltage [log(ID) - VGS] transfer curves at temperatures from -50°C to +50°C. These bottom-gate staggered a-IGZO TFTs are fabricated using thermal silicon dioxide as the gate insulator. An almost rigid log(ID) - VGS

Ken Hoshino; John F. Wager

2010-01-01

230

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

231

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

232

Comment on "Methodology and results of calculating Central California surface temperature trends: evidence of human-induced climate change?" by Christy et al. (2006)  

SciTech Connect

Understanding the causes of observed regional temperature trends is essential to projecting the human influences on climate, and the societal impacts of these influences. In their recent study, Christy et al. (2006, hereinafter CRNG06) hypothesized that the presence of irrigated soils is responsible for rapid warming of summer nights occurring in California's Central Valley over the last century (1910-2003), an assumption that rules out any significant effect due to increased greenhouse gases, urbanization, or other factors in this region. We question this interpretation, which is based on an apparent contrast in summer nighttime temperature trends between the San Joaquin Valley ({approx} +0.3 {+-} 0.1 C/decade) and the adjacent western slopes of the Sierra Nevada (-0.25 {+-} 0.15 C/decade), as well as the amplitude, sign and uncertainty of the Sierra nighttime temperature trend itself. We, however, do not dispute the finding of other Sierra and Valley trends. Regarding the veracity of the apparent Sierra nighttime temperature trend, CRNG06 generated the Valley and Sierra time-series using a meticulous procedure that eliminates discontinuities and isolates homogeneous segments in temperature records from 41 weather stations. This procedure yields an apparent cooling of about -0.25 {+-} 0.15 C/decade in the Sierra region. However, because removal of one of the 137 Sierra segments, from the most elevated site (Huntington Lake, 2140m), causes an increase in nighttime temperature trend as large as the trend itself (of +0.25 C/decade, CH06), and leads to a zero trend, the apparent cooling of summer nights in the Sierra regions seems, in fact, largely uncertain.

Bonfils, C; Duffy, P; Lobell, D

2006-03-28

233

Consistency Check for Trends in Surface Temperature and Upper-Level Circulation: 1950-1992.  

NASA Astrophysics Data System (ADS)

A time series of 43 years of observed monthly mean air temperature at 109 sites in the 48 contiguous United States is compared to monthly mean air temperature specified from hemispheric gridded 700-mb heights. Because both upper-air and surface data have problems that may limit their use in climate change studies, this comparison could be considered a mutual consistency check. Cooling (by about 0.5°C) from 1951 to about 1970 and subsequent warming (also by 0.5°C) that continues through the present are found in both datasets, indicating that these interdecadal changes are probably real.In the List several years the specified temperatures were often colder than those observed. This prompted an investigation of whether the `residual' (specified minus observed) has recently been large (and negative) compared to the earlier part of the record. It was found that for the same 700-mb height field, surface temperatures were almost a degree Celsius warmer in the last few years than they were in the early 1950s, but considering the variability of the residuals over the 1950-92 period, the recent cold residuals may not yet be strikingly unusual.By comparing the full set of 109 stations to a `clean' subset of 24, the impact of common problems in surface data (station relocation, urbanization, etc.) was found to be quite small. The rather favorable comparison of observed surface temperatures and specified surface temperatures (which suffer from upper-air analysis / observation changes over the years) indicates that their respective data problems do not appear to invalidate their use in studies of interdecadal temperature change.

van den Dool, Huug M.; O'Lenic, Edward A.; Klein, William H.

1993-12-01

234

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

235

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

236

Glass transition temperature of bulk metallic glasses: A linear connection with the mixing enthalpy  

NASA Astrophysics Data System (ADS)

A linear relationship is found between the glass transition temperature Tg and the absolute value of the mixing enthalpy, |?Hchem|, for bulk metallic glass systems. The increasing (or lowering) of Tg with an admixture of metals or other elements manifests itself in the larger (or smaller) of |?Hchem| in a given system. The results indicate that the composition dependence of Tg results from the change of excess entropy (Sex) during thermal excitation. The |?Hchem|, which relates to the strength of interaction among different atoms, corresponds to part of the Sex at Tg [Sex(Tg)]. The glass transition temperatures for Cu-Zr (Hf)-, Zr-Cu-, and La-Al-based glassy alloys are correlated with the interaction intensity between their based binary eutectic compositions, respectively.

Li, Xuelian; Bian, Xiufang; Hu, Lina; Wu, Yuqin; Guo, Jing; Zhang, Junyan

2007-05-01

237

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

238

MY NASA DATA: Sea Surface Temperature Trends of the Gulf Stream  

NSDL National Science Digital Library

In this three-part lesson, students explore the Live Access Server (LAS) and produce plots of sea surface temperature. They then prepare a time series of data for particular location(s) on the Gulf Stream and use Excel to produce and analyze graphs of sea surface temperature. One of the most studied and important ocean currents of the world lies along the eastern coast of the United States and is called the Gulf Stream. It derives its name from its source region of warm water in the Gulf of Mexico. For the past two decades, scientists have been collecting sea surface temperature (SST) data from satellites, buoys and ships in the Gulf Stream and Atlantic Basin. The lesson provides detailed procedure, related links, sample graphs, follow-up questions, extensions, and teacher notes.

2007-01-01

239

Correlation and Trend Studies of the Sea Ice Cover and Surface Temperatures in the Arctic  

NASA Technical Reports Server (NTRS)

Co-registered and continuous satellite data of sea ice concentrations and surface ice temperatures from 1981 to 1999 are analyzed to evaluate relationships between these two critical climate parameters and what they reveal in tandem about the changing Arctic environment. During the 18-year period, the actual Arctic ice area is shown to be declining at a rate of 3.1 +/- 0.4 % /decade while the surface ice temperature has been increasing at 0.4 +/- 0.2 K /decade. Yearly anomaly maps also show that the ice concentration anomalies are predominantly positive in the 1980s and negative in the 1990s while surface temperature anomalies were mainly negative in the 1980s and positive in the 1990s. The yearly ice concentration and surface temperature anomalies are shown to be highly correlated indicating a strong link especially in the seasonal region and around the periphery of the perennial ice cover. The surface temperature data are also especially useful in providing the real spatial scope of each warming (or cooling) phenomenon that usually extends beyond the boundaries of the sea ice cover. Studies of the temporal variability of the summer ice minimum also reveal that the perennial ice cover has been declining at the rate of 6.6% /decade while the summer surface ice temperature has been increasing at the rate of 1.3 K /decade. Moreover, high year-to-year fluctuations in the minimum ice cover in the 1990s may have caused reductions in average thickness of the Arctic sea ice cover.

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

2001-01-01

240

The Relation Between Atmospheric Humidity and Temperature Trends for Stratospheric Water  

NASA Technical Reports Server (NTRS)

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 higherfrequency 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

241

One Hundred Years of New York City's "Urban Heat Island": Temperature Trends and Public Health Impacts  

NASA Astrophysics Data System (ADS)

In this paper, we examine the relationship between the historical development of New York City and its effect on the urban climate. Urban "heat islands" (UHI) are created principally by man-made surfaces, including concrete, dark roofs, asphalt lots and roads, which absorb most of the sunlight falling on them and reradiate that energy as heat. Many urban streets have fewer trees and other vegetation to shade buildings, block solar radiation and cool the air by evapotranspiration. The historical development of the NYC heat island effect was assessed in terms of average temperature differences of the city center relative to its surrounding 31-county metropolitan region, comprised of parts of New York State, New Jersey, and Connecticut. Monthly maximum and minimum temperatures for 1900-1997 were obtained from NOAA's National Climatic Data Center, the NASA-Goddard Institute for Space Studies, and the Lamont-Doherty Earth Observatory of Columbia University for 24 weather stations within the region that are part of the U.S. Historical Climatology Network. Analysis of annual mean temperatures shows an increasing difference between NYC (Central Park weather station) and its surrounding region over the twentieth century. Analysis of the temperature differences over time between NY Central Park (NYCP) station and 23 regional weather stations classified according to distance and level of urbanization show a heat island effect existing in NYC, with mean temperatures in the NYCP Station generally higher than the surrounding stations, ranging from 1.20\\deg C to 3.02\\deg C. A difference of at least 1\\deg C already existed at the beginning of the 20th century between the mean temperature in NYC and its surrounding rural areas, and this difference increased over the twentieth century. There was a significant decrease in the monthly and seasonal variability of the UHI effect over the century. Temperature extremes and summertime heat can create heat stress and other health consequences for urban residents. Public health impacts are assessed as the proportion of heat-related regional mortality estimated to be attributable to New York City's heat island effect during an average 1990's summer. Concentration-response functions describing the temperature-mortality relationship in NYC derived from the epidemiological literature are used to estimate numbers of deaths in a typical 1990s summer and those attributable to the city's heat island effect. The techniques and potential public health benefits of a pilot project to mitigate the heat island effect in NYC will be discussed.

Rosenthal, J. E.; Knowlton, K. M.; Rosenzweig, C.; Goldberg, R.; Kinney, P. L.

2003-12-01

242

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

243

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

244

Annual and seasonal analysis of temperature and precipitation in Andorra (Pyrenees) from 1934 to 2008: quality check, homogenization and trends  

NASA Astrophysics Data System (ADS)

The analysis of temperature and precipitation change and variability in high elevations is a difficult issue due to the lack of long term climatic series in those environments. Nonetheless, it is important to evaluate how much high elevations follow the same climate evolution than low lying sites. In this work, using daily data from three Andorran weather stations (maintained by the power company Forces Elèctriques d'Andorra, FEDA), climate trends of annual and seasonal temperature and precipitation were obtained for the period 1934-2008. The series are complete (99.9%) and are located in a mountainous area ranging from 1110 m to 1600 m asl. As a previous step to the analysis, data rescue, quality control and homogeneity tests were applied to the daily data. For quality control, several procedures were applied to identify and flag suspicious or erroneous data: duplicated days, outliers, excessive differences between consecutive days, flat line checking, days with maximum temperature lower that minimum temperature, and rounding analysis. All the station sites were visited to gather the available metadata. Concerning homogeneity, a homogeneous climate time series is defined as one where variations are caused only by variations in climate and not to non-climatic factors (i.e., changes in site location, instruments, station environment…). As a result, homogeneity of the series was inspected from several methodologies that have been used in a complementary and independent way in order to attain solid results: C3-SNHT (with software developed under the Spanish Government Grant CGL2007-65546-C03-02), and Caussinus-Mestre (C-M) approaches. In both cases, tests were applied to mean annual temperature and precipitation series, using Catalan and French series as references (provided respectively by the Meteorological Service of Catalonia and Météo-France, in the framework of the Action COST-ES0601: Advances in homogenisation methods of climate series: an integrated approach, HOME). For precipitation, an additional test - RhTestV3 - was applied over the station data to ensure the homogeneity of the series. The analysis of the quality-controlled and homogenized maximum and minimum temperature series, shows an increase and statistically significant trend for the period 1934-2008. More precisely, the results are significant for both approaches (C3-SNHT and C-M) and for annual maximum temperature (0.12 and 0.10°C/decade, respectively), maximum summer temperature (0.25 and 0.17°C/decade, respectively), and minimum winter temperature (0.18 and 0.11°C/decade, respectively). The results were also obtained for the period 1971-2008. It is observed that the upward trend of the temperature has been reinforced in Andorra for this most recent period. Regarding precipitation, with the application of different tests, non-significant results for all the seasons and for the whole period (1934-2008) were obtained, so it cannot be concluded any increasing or decreasing trend. Nevertheless, preliminary results for the 1950-2008 period aim clearly towards a significant decrease of the annual total accumulation (-4.26mm/decade [being -7.80/-1.03, the confidence intervals at 95% level]), being especially relevant and also significant for the summer totals (-2.44 mm/decade [being -3.74/-1.13, the confidence intervals at 95% level]). The obtained trends for temperature agree with those obtained in Spain (Brunet et al., 2007), France (Spagnoli et al., 2002 and Maris et al., 2009) and Catalonia (Meteorological Service of Catalonia, 2008). Bibliography: - Brunet M, Jones PD, Sigró J, Saladié O, Aguilar E, Moberg A, Della-Marta PM, Lister D, Whalter A, López D. 2007. Temporal and spatial temperature variability and change over Spain during 1850-2005. Journal of Geophysical Research,, 112, D12117, doi:10.1029/2006JD008249 - Butlletí Anual d'Indicadors Climàtics, 2008 (BAIC,2008). Àrea de Climatologia, Servei Meteorològic de Catalunya. (http://www.meteo.cat) - Spagnoli B, Planton S, Mestre O, Déqué M, Moisselin, JM (2002). Detecting climate change

Esteban, Pere; Prohom, Marc; Aguilar, Enric; Mestre, Olivier

2010-05-01

245

Temperature in Science Textbooks: Changes and Trends in Cross-National Perspective (1950-2000)  

ERIC Educational Resources Information Center

This study explores the way the concept of temperature was presented in lower-secondary science textbooks in France, Poland and England at the end of the 1950s and in the 2000s. I draw on history of science, history of education and book history to analyze different treatments of an apparently-similar scientific concept with regard to national…

Radtka, Catherine

2013-01-01

246

Trends, spectral characteristics, and rainfall relationships of low-latitude sea surface temperatures at different longitudes  

Microsoft Academic Search

The sea surface temperature (SST) data for low latitudes in the Pacific, Atlantic, and Indian Oceans for 1950-1996 (47 years) showed different seasonal variation patterns at different longitudes. When the seasonal patterns were subtracted from the monthly values, the deseasoned residuals showed considerable anomalies (interannual variability). In the Pacific the main features were the El Niño events. In the Atlantic,

R. P. Kane

2000-01-01

247

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

E-print Network

of ancient Bristlecone Pines to temperature varies with the degree of moisture-stress the trees experience traditionally been recon- structed 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

Stott, Lowell

248

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

249

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

250

The trends and dependencies between air and water temperatures in lakes in northern Poland in 19612000 Hydrology and Earth System Sciences, 8(1), 7987 (2004) EGU  

E-print Network

The trends and dependencies between air and water temperatures in lakes in northern Poland between air and water temperatures in lakes in northern Poland from 19612000 Mieczyslaw Dabrowski1, Branch in Bialystok, ul. Ciolkowskiego 2/3, 15-245 Bialystok, Poland 2 Nicolaus Copernicus University

Paris-Sud XI, Université de

251

The Interaction Between Trends and Periodical Components in Air and Soil Temperature Time-Series Over the Asian Territory of Russia  

Microsoft Academic Search

We used Singular Spectrum Analysis (SSA) to detect trend and periodic components (rhythms) in annual and seasonal time series of surface air temperature (SAT) and of soil temperature (ST) at depths of 40, 160, and 320 cm, for the northern (to the north of the 60th latitude) and southern (to the south of the 60th latitude) parts of Western Siberian

S. M. Chudinova; T. Zhang; R. G. Barry; V. Sorokovikov; D. Gilichinsky

2004-01-01

252

Temperature in Science Textbooks: Changes and Trends in Cross-National Perspective (1950-2000)  

NASA Astrophysics Data System (ADS)

This study explores the way the concept of temperature was presented in lower-secondary science textbooks in France, Poland and England at the end of the 1950s and in the 2000s. I draw on history of science, history of education and book history to analyze different treatments of an apparently-similar scientific concept with regard to national contexts and diachronic change. Thus I include a presentation of the contexts in which the textbooks I study are published, and I analyse textbooks content revealing different approaches to present the notion of temperature. I argue that these results show that textbooks are valuable sources to investigate public representations of science and their shift over time, and I conclude by stressing the parallel of this evolution with change in everyday relationship with science and scientific instruments.

Radtka, Catherine

2013-04-01

253

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

254

Linking climate trends to population dynamics in the Baltic ringed seal: impacts of historical and future winter temperatures.  

PubMed

A global trend of a warming climate may seriously affect species dependent on sea ice. We investigated the impact of climate on the Baltic ringed seals (Phoca hispida botnica), using historical and future climatological time series. Availability of suitable breeding ice is known to affect pup survival. We used detailed information on how winter temperatures affect the extent of breeding ice and a climatological model (RCA3) to project the expected effects on the Baltic ringed seal population. The population comprises of three sub-populations, and our simulations suggest that all of them will experience severely hampered growth rates during the coming 90 years. The projected 30, 730 seals at the end of the twenty-first century constitutes only 16 % of the historical population size, and thus reduced ice cover alone will severely limit their growth rate. This adds burden to a species already haunted by other anthropogenic impacts. PMID:22851349

Sundqvist, Lisa; Harkonen, Tero; Svensson, Carl Johan; Harding, Karin C

2012-12-01

255

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

256

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

257

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

PubMed

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

2012-11-01

258

Comparison of non-linear temperature-dependent development rate models applied to in vitro growth of entomopathogenic fungi  

Microsoft Academic Search

Five non-linear models with three to five parameters, built to quantify the effect of temperature on insect development and microbial growth, were tested to describe the influence of temperature on in vitro-measured growth rates of entomopathogenic hyphomycetes. Data from two isolates of each of the four fungal species, Paecilomyces fumosoroseus, Beauveria bassiana, Metarhizium anisopliae, Metarhizium flavoviride, were used to assess

Nathalie Smits; Jean-François BriÈRe; Jacques Fargues

2003-01-01

259

Temperature driven p-n-p type conduction switching materials: current trends and future directions.  

PubMed

Modern technological inventions have been going through a "renaissance" period. Development of new materials and understanding of fundamental structure-property correlations are the important steps to move further for advanced technologies. In modern technologies, inorganic semiconductors are the leading materials which are extensively used for different applications. In the current perspective, we present discussion on an important class of materials that show fascinating p-n-p type conduction switching, which can have potential applications in diodes or transistor devices that operate reversibly upon temperature or voltage change. We highlight the key concepts, present the current fundamental understanding and show the latest developments in the field of p-n-p type conduction switching. Finally, we point out the major challenges and opportunities in this field. PMID:25812630

Guin, Satya N; Biswas, Kanishka

2015-04-01

260

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

261

Vector and axial-vector mesons at nonzero temperature within a gauged linear sigma model  

SciTech Connect

We consider vector and axial-vector mesons in the framework of a gauged linear sigma model with chiral U(N{sub f}){sub R}xU(N{sub f}){sub L} symmetry. For N{sub f}=2, we investigate the behavior of the chiral condensate and the meson masses as a function of temperature by solving a system of coupled Dyson-Schwinger equations derived via the 2PI formalism in double-bubble approximation. We find that the inclusion of vector and axial-vector mesons tends to sharpen the chiral transition. Within our approximation scheme, the mass of the {rho} meson increases by about 100 MeV towards the chiral transition.

Strueber, Stefan; Rischke, Dirk H. [Institut fuer Theoretische Physik, Johann Wolfgang Goethe-Universitaet, Max-von-Laue-Str. 1, D-60438 Frankfurt/Main (Germany); Institut fuer Theoretische Physik and Frankfurt Institute for Advanced Studies, Johann Wolfgang Goethe-Universitaet, Max-von-Laue-Str. 1, D-60438 Frankfurt/Main (Germany)

2008-04-15

262

Phase Diagram of the Linear Sigma Model wiht Quarks at Finite Temperature and Density  

NASA Astrophysics Data System (ADS)

The study of QCD at low energies is relevant in explaining the world around us but is extremely difficult due to the mathematical structure of the theory. The linear sigma model is a well known and simple effective model for low-energy QCD. We couple the O(4) linear sigma model to quark fields in order to study the effects of the quarks and mesons on the chiral phase transition as functions of the temperature T and the quark chemical potential ?q. As an effective model for QCD, we hope to reproduce some aspects of the QCD phase diagram, namely, the line of first order transitions that has a critical end-point at a second order transiton. We study how this line varies with changing pion mass. We use the self-consistent Cornwall-Jackiw-Tomboulis method in an extended Hartree approximation using a summation over all daisy diagrams. We study the mesonic and quark properties, including mean field, fluctuations and effective masses and how they relate to the transition structure.

Bowman, Edwin; Kapusta, Joseph; Kolomeitsev, Evgeni

2008-04-01

263

The Orthorhomic Structure of CaCo[subscript 3], SrCO[subscript 3], PbCO[subscript 3] and BaCO[subscript 3]: Linear Structural Trends  

SciTech Connect

The crystal structures of four isostructural orthorhombic carbonates, CaCO{sub 3} (aragonite), SrCO{sub 3} (strontianite), PbCO{sub 3} (cerussite), and BaCO{sub 3} (witherite), were obtained by Rietveld refinements using data acquired by synchrotron high-resolution powder X-ray diffraction (HRPXRD). For BaCO{sub 3}, powder neutron-diffraction data were obtained and refined by the Rietveld method. For aragonite, we also carried out a refinement of the structure by single-crystal X-ray diffraction. These carbonates belong to the space group Pmcn, with Z = 4. The CO{sub 3} group is slightly non-planar, and the two independent C-O distances are slightly different. The CO{sub 3} group becomes more symmetrical and less aplanar from CaCO{sub 3} to BaCO{sub 3} (M{sub radii}{sup 2+}: Ca < Sr < Pb < Ba). The CaCO{sub 3} structure is, therefore, the most distorted, whereas the BaCO{sub 3} structure is the least distorted. Several linear structural trends are observed in plots of selected parameters as a function of the unit-cell volume, V. These parameters are radii of the nine-coordinated M{sup 2+} cations, the unit-cell axes, the average and distances, average angle, and aplanarity. These linear trends are the result of the effective size of the divalent ionic radius of the M cations that are coordinated to nine oxygen atoms. The geometrical features of the CO{sub 3} group can be obtained reliably only by using neutron-diffraction data, especially in the presence of other heavy atoms.

Antao, Sytle M.; Hassan, Ishmael; (Calgary); (West Indies)

2010-11-12

264

Trends in Mars Thermospheric Density and Temperature Structure Obtained from MAVEN In-situ Datasets: Interpretation Using Global Models  

NASA Astrophysics Data System (ADS)

The Mars thermosphere-ionosphere-exosphere (TIE) system constitutes the atmospheric reservoir (i.e. available cold and hot planetary neutral and thermal ion species) that regulates present day escape processes from the planet. Without knowledge of the physics and chemistry creating this TIE region and driving its variations (e.g., solar cycle, seasonal), it is not possible to constrain either the short-term or long-term histories of atmosphere escape. The characterization of this upper atmosphere reservoir is one of the major science objectives of the MAVEN mission.We investigate both in-situ Neutral Gas and Ion Mass Spectrometer (NGIMS) neutral densities/temperatures and Accelerometer Experiment (ACC) reaction wheel (RW) derived mass densities/temperatures obtained over the first ~400 orbits. This sampling occurs when periapsis latitudes ranged from about 32° to 74°N periapsis local mean solar times (LMST) ranged from about 15:00 to 06:00; and corresponding periapsis altitudes ranged from ~200 km down to ~150 km. This dayside in-situ sampling lasted until about 17-December-2014, after which the periapsis began moving Southward toward nightside Northern mid-latitudes. During this dayside period, monthly mean solar EUV-UV fluxes corresponded to F10.7 ~ 150-160 at Earth (solar moderate conditions) and the Martian season was approaching perihelion (Ls ~ 205 to 254°).Thermospheric trends (e.g. latitude, local time, diurnal) of extracted densities and inferred temperatures will be compared with corresponding 3-D Mars Global Ionosphere-Thermosphere Model (M-GITM) simulated outputs in order to understand the variations observed, and probe the underlying physical processes responsible. Solar rotation variations in EUV fluxes and their impacts on dayside temperatures will also be examined.

Bougher, Stephen W.; Tolson, Robert H.; Mahaffy, Paul R.; Johnston, Timothy E.; Olsen, Kirk; Bell, Jared M.

2015-04-01

265

Long-term trends and extremes in observed daily precipitation and near surface air temperature in the Philippines for the period 1951-2010  

NASA Astrophysics Data System (ADS)

Observed daily precipitation and near surface air temperature data from 34 synoptic weather stations in the Philippines for the period 1951-2010 were subjected to trend analysis which revealed an overall warming tendency compared to the normal mean values for the period 1961-1990. This warming trend can be observed in the annual mean temperatures, daily minimum mean temperatures and to a lesser extent, daily maximum mean temperatures. Precipitation and temperature extremes for the period 1951-2010 were also analysed relative to the mean 1961-1990 baseline values. Some stations (Cotabato, Iloilo, Laoag and Tacloban,) show increases in both frequency and intensity of extreme daily rainfall events which are significant at the 95% level with none of the stations showing decreasing trends. The frequency of daily temperature maximum above the 99th percentile (hot days) and nights at the 1st percentile (cold nights) suggests that both days and nights in particular are becoming warmer. Such indicators of a warming trend and increase in extreme events in the Philippines are discussed in the context of similar national, regional (Asia Pacific) and global studies. The relevance of such empirically based climatology studies, particularly for nations such as the Philippines which are increasingly vulnerable to the multiple impacts of global climate change, is also considered.

Cinco, Thelma A.; de Guzman, Rosalina G.; Hilario, Flaviana D.; Wilson, David M.

2014-08-01

266

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

267

Temperature Changes between Neighboring Days and Mortality in Summer: A Distributed Lag Non-Linear Time Series Analysis  

PubMed Central

Background Many studies have shown that high temperatures or heat waves were associated with mortality and morbidity. However, few studies have examined whether temperature changes between neighboring days have any significant impact on human health. Method A distributed lag non-linear model was employed to investigate the effect of temperature changes on mortality in summer during 2006–2010 in two subtropical Chinese cities. The temperature change was defined as the difference of the current day’s and the previous day’s mean temperature. Results We found non-linear effects of temperature changes between neighboring days in summer on mortality in both cities. Temperature increase was associated with increased mortality from non-accidental diseases and cardiovascular diseases, while temperature decrease had a protective effect on non-accidental mortality and cardiovascular mortality in both cities. Significant association between temperature changes and respiratory mortality was only found in Guangzhou. Conclusion This study suggests that temperature changes between neighboring days might be an alternative temperature indicator for studying temperature-mortality relationship. PMID:23826095

Lin, Hualiang; Zhang, Yonghui; Xu, Yanjun; Xu, Xiaojun; Liu, Tao; Luo, Yuan; Xiao, Jianpeng; Wu, Wei; Ma, Wenjun

2013-01-01

268

Recent summer precipitation trends in the Greater Horn of Africa and the emerging role of Indian Ocean sea surface temperature  

NASA Astrophysics Data System (ADS)

We utilize a variety of climate datasets to examine impacts of two mechanisms on precipitation in the Greater Horn of Africa (GHA) during northern-hemisphere summer. First, surface-pressure gradients draw moist air toward the GHA from the tropical Atlantic Ocean and Congo Basin. Variability of the strength of these gradients strongly influences GHA precipitation totals and accounts for important phenomena such as the 1960s-1980s rainfall decline and devastating 1984 drought. Following the 1980s, precipitation variability became increasingly influenced by the southern tropical Indian Ocean (STIO) region. Within this region, increases in sea-surface temperature, evaporation, and precipitation are linked with increased exports of dry mid-tropospheric air from the STIO region toward the GHA. Convergence of dry air above the GHA reduces local convection and precipitation. It also produces a clockwise circulation response near the ground that reduces moisture transports from the Congo Basin. Because precipitation originating in the Congo Basin has a unique isotopic signature, records of moisture transports from the Congo Basin may be preserved in the isotopic composition of annual tree rings in the Ethiopian Highlands. A negative trend in tree-ring oxygen-18 during the past half century suggests a decline in the proportion of precipitation originating from the Congo Basin. This trend may not be part of a natural cycle that will soon rebound because climate models characterize Indian Ocean warming as a principal signature of greenhouse-gas induced climate change. We therefore expect surface warming in the STIO region to continue to negatively impact GHA precipitation during northern-hemisphere summer.

Williams, A. Park; Funk, Chris; Michaelsen, Joel; Rauscher, Sara A.; Robertson, Iain; Wils, Tommy H. G.; Koprowski, Marcin; Eshetu, Zewdu; Loader, Neil J.

2012-11-01

269

Monitoring and trend mapping of sea surface temperature (SST) from MODIS data: a case study of Mumbai coast.  

PubMed

Sea surface temperature (SST) is one of the most important parameters in monitoring ecosystem health in the marine and coastal environment. Coastal ecosystem is largely dependent on ambient temperature and temperature fronts for marine/coastal habitat and its sustainability. Hence, thermal pollution is seen as a severe threat for ecological health of coastal waters across the world. Mumbai is one of the largest metropolises of the world and faces severe domestic and industrial effluent disposal problem, of which thermal pollution is a major issue with policy-makers and environmental stakeholders. This study attempts to understand the long-term SST variation in the coastal waters off Mumbai, on the western coast of India, and to identify thermal pollution zones. Analysis of SST trends in the near-coastal waters for the pre- and post-monsoon seasons from the year 2004 to the year 2010 has been carried out using Moderate Resolution Imaging Spectro-radiometer (MODIS) Thermal Infra-red (TIR) bands. SST is calculated with the help of bands 31 and 32 using split window method. Several statistical operations were then applied to find the seasonal averages in SST and the standard deviation of SST in the study area. Maximum variation in SST was found within a perpendicular distance of 5 km from the shoreline during the study period. Also, a warm water mass was found to form consistently off coast during the winter months. Several anthropogenic sources of thermal pollution could be identified which were found to impact various locations along the coast. PMID:25743152

Azmi, Samee; Agarwadkar, Yogesh; Bhattacharya, Mohor; Apte, Mugdha; Inamdar, Arun B

2015-04-01

270

Low-temperature phases obtained by linear programming: An application to a lattice system of model chiral molecules  

Microsoft Academic Search

A convenient, Peierls-type approach to obtain low-temperature phases is to use the method of an m-potential. In this paper we show that, for more complex systems where it may be rather difficult to rewrite the Hamiltonian as an m-potential and whose configurations are subject to linear constraints, the verification of the Peierls condition can be reformulated as a linear programming

Igor Medved; Anton Trník; Dale A. Huckaby

2011-01-01

271

Design of a platinum resistance thermometer temperature measuring transducer and improved accuracy of linearizing the output voltage  

SciTech Connect

An improved method is presented for designing a temperature measuring transducer, the electrical circuit of which comprises an unbalanced bridge, in one arm of which is a platinum resistance thermometer, and containing a differential amplifier with feedback. Values are given for the coefficients, the minimum linearization error is determined, and an example is also given of the practical design of the transducer, using the given coefficients. A determination is made of the limiting achievable accuracy in linearizing the output voltage of the measuring transducer, as a function of the range of measured temperature.

Malygin, V.M.

1995-06-01

272

Prediction of tropical Atlantic sea surface temperatures using linear inverse modeling  

SciTech Connect

The predictability of tropical Atlantic sea surface temperature on seasonal to interannual timescales by linear inverse modeling is quantified. The authors find that predictability of Caribbean Sea and north tropical Atlantic sea surface temperature anomalies (SSTAs) is enhanced when one uses global tropical SSTAs as predictors compared with using only tropical Atlantic predictors. This predictability advantage does not carry over into the equatorial and south tropical Atlantic; indeed, persistence is a competitive predictor in those regions. To help resolve the issue of whether or not the dipole structure found by applying empirical orthogonal function analysis to tropical Atlantic SSTs is an artifact of the technique or a physically real structure, the authors combine empirically derived normal modes and their adjoints to form influence functions, maps highlighting the geographical areas to which the north tropical Atlantic and the south tropical Atlantic SSTs are most sensitive at specified lead times. When the analysis is confined to the Atlantic basin, the 6-month influence functions in the north and south tropical Atlantic tend to be of the opposite sign and evolve into clear dipoles within 6 months. When the analysis is performed on global tropical SSTs, the 6-month influence functions are connected to the El Nino phenomenon in the Pacific, with the strongest signal in the north tropical Atlantic. That is, while the south tropical Atlantic region is weakly sensitive to the optimal initial structure for growth of El Nino, SST anomaly in the Nino 3 region is a strong 6-month predictor of SST anomaly in the north tropical Atlantic. The results suggest that the tropical Atlantic dipole is a real phenomenon rather than an artifact of EOF analysis but that the influence of the Indo-Pacific often disrupts the northern branch so that the dipole does not dominate tropical Atlantic dynamics on seasonal timescales. 38 refs., 12 figs., 1 tab.

Penland, C.; Matrosova, L. [Univ. of Colorado, Boulder, CO (United States)] [Univ. of Colorado, Boulder, CO (United States)

1998-03-01

273

Variability and trend of diurnal temperature range in China and their relationship to total cloud cover and sunshine duration  

NASA Astrophysics Data System (ADS)

This study aims to investigate the effect of total cloud cover (TCC) and sunshine duration (SSD) in the variation of diurnal temperature range (DTR) in China during 1954-2009. As expected, the inter-annual variation of DTR was mainly determined by TCC. Analysis of trends of 30-year moving windows of DTR and TCC time series showed that TCC changes could account for that of DTR in some cases. However, TCC decreased during 1954-2009, which did not support DTR reduction across China. DTRs under sky conditions such as clear, cloudy and overcast showed nearly the same decreasing rate that completely accounted for the overall DTR reduction. Nevertheless, correlation between SSD and DTR was weak and not significant under clear sky conditions in which aerosol direct radiative effect should be dominant. Furthermore, 30-60% of DTR reduction was associated with DTR decrease under overcast conditions in south China. This implies that aerosol direct radiative effect appears not to be one of the main factors determining long-term changes in DTR in China.

Xia, X.

2013-05-01

274

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

275

Driving models of high temperature superconducting linear synchronous motors and characteristic analysis  

NASA Astrophysics Data System (ADS)

Driving models of high temperature superconducting (HTS) linear synchronous motors (LSM) are studied and extracted from the HTS LSM technology developed to date. An HTS LSM using an HTS bulk magnet secondary has been developed and presented for technical verification. The HTS LSM drive combined with an HTS bulk-permanent magnet guideway (PMG) system for magnetic levitation results in running without sliding friction and having the functions of self-levitation and self-guidance without the need for a compulsory active control system. In this paper, driving models of the HTS LSMs are introduced with numerical analysis results. Different magnetization methods are applied to obtain the HTS bulk magnets, and the HTS magnetization characteristics using those methods are identified. Two types of PMGs are designed and prepared whose magnetic field distributions are simulated and practically tested for comparison. Comprehensive experiments have been conducted on the HTS LSM drive. The practical results obtained show that the HTS LSM developed has applicable thrust characteristics without the conventional friction, and a better practical performance can be achieved by using HTS bulk magnets having a higher trapped magnetic field.

Xun Jin, Jian; Hai Zheng, Lu

2011-05-01

276

Abrupt changes, multidecadal variability and long-term trends in sea surface temperature and sea level datasets within the southeastern Bay of Biscay  

NASA Astrophysics Data System (ADS)

Multidecadal variability and long-term trends of Sea Surface Temperature (SST) and Sea Level (SL) datasets for the southeastern Bay of Biscay have been examined. The SST dataset (Aquarium of San Sebastián), measured on a nearly daily basis, extends from 1947 to 2010. The daily SL data utilised are those from Santander (IEO tide gauge network) and from St. Jean de Luz (SHOM), spanning the periods 1943-2004 and 1964-1997, respectively. This paper presents an approach for the extraction of multidecadal variability and long-term trends. First of all, the KZA (Kolmogorov-Zurbenko Adaptive) filter was used to detect possible discontinuities in time-series. Subsequently, the seasonal and multidecadal variability was identified by spectral analysis and further quantified by least squares fitting. Finally, prior to the trend determination, the long-term natural variability was removed. The results revealed significant contribution of the annual component to the SST and SL, with a weaker contribution of the semiannual signal. The sea level air pressure and long-term tides also contributed to the SL variability. The estimated trends were less than those obtained by other authors. The analysis revealed no trend in the SST and the Jean de Luz SL series, whilst an increasing trend was detected for the Santander SL dataset.

González, Manuel; Fontán, Almudena; Esnaola, Ganix; Collins, Michael

2013-01-01

277

Studies on Mixed Slab-Toroidal Electron Temperature Gradient Mode Instabilities in the Columbia Linear Machine  

NASA Astrophysics Data System (ADS)

This thesis investigates the behavior of electron temperature gradient (ETG) driven instabilities in the Columbia Linear Machine (CLM). Building on prior work in CLM, the primary goal of this research is to produce, identify, and illuminate the basic physics of these instabilities, and explore the behavior of these instabilities under the presence of trapping and curved magnetic field lines. The first part of this thesis is focused on studying the saturated ETG mode, and the general behavior of the mode under varying levels of magnetic curvature. Measuring ETG modes can be problematic since they have large real frequencies, fast growth rates (~MHz) and small spatial scales, but carefully designed probe diagnostics can overcome these limits. In order to produce curved magnetic field lines, we modified CLM to operate with an internal movable mirror coil. We determined the temperature and density profiles under varying curvature, and measured changes in the mode structure and frequency. We found small changes in the azimuthal/poloidal structure and frequency, characterized by an increase in the m-number (mslab˜10-13 and Deltam˜1), along with small changes in the axial/toroidal structure (k??, curvature < k??, slab) and frequency (ocurvature < oslab). We also present one of the first experimental scaling of ETG mode amplitude as a function of curvature. Our key finding was a that overall levels of saturated ETG mode amplitude had a modest increase (˜1.5x) which is slightly larger than existing theory and simulations would predict, and that the power density and amplitude of individual mode peaks can increase more dramatically (˜2-3x amplitude). The second part of this thesis studies the radial transport for saturated ETG modes in CLM. ETG modes are believed to be a significant source of anomalous electron energy transport in plasmas, and a better understanding of these modes and the transport they drive across magnetic field lines is of particular interest for advanced tokamaks and future fusion reactors, where these is a continued push for energy efficiency. A specially designed triple probe has been developed, which can measure fluctuations in temperature and potential simultaneously, with a high frequency and special resolution suitable for ETG studies. We present an experimental scaling of radial transport as a function of magnetic field curvature, again one of the first of its kind. Our findings indicate a modest increase in radial transport (˜2x) with increased curvature, but unlike saturated mode amplitudes, we find that radial transport saturates for higher levels of curvature in CLM.

Balbaky, Abed

278

High Spatial Resolution Forecasting of Long-Term Monthly Precipitation and Mean Temperature Trends in Data Scarce Regions  

NASA Astrophysics Data System (ADS)

High spatial resolution time-series data are critical for many hydrological and earth science studies. Multiple groups have developed historical and forecast datasets of high-resolution monthly time-series for regions of the world such as the United States (e.g. PRISM for hindcast data and MACA for long-term forecasts); however, analogous datasets have not been available for most data scarce regions. The current work fills this data need by producing and freely distributing hindcast and forecast time-series datasets of monthly precipitation and mean temperature for all global land surfaces, gridded at a 30 arc-second resolution. The hindcast data are constructed through a Delta downscaling method, using as inputs 0.5 degree monthly time-series and 30 arc-second climatology global weather datasets developed by Willmott & Matsuura and WorldClim, respectively. The forecast data are formulated using a similar downscaling method, but with an additional step to remove bias from the climate variable's probability distribution over each region of interest. The downscaling package is designed to be compatible with a number of general circulation models (GCM) (e.g. with GCMs developed for the IPCC AR4 report and CMIP5), and is presently implemented using time-series data from the NCAR CESM1 model in conjunction with 30 arc-second future decadal climatologies distributed by the Consultative Group on International Agricultural Research. The resulting downscaled datasets are 30 arc-second time-series forecasts of monthly precipitation and mean temperature available for all global land areas. As an example of these data, historical and forecast 30 arc-second monthly time-series from 1950 through 2070 are created and analyzed for the region encompassing Pakistan. For this case study, forecast datasets corresponding to the future representative concentration pathways 45 and 85 scenarios developed by the IPCC are presented and compared. This exercise highlights a range of potential meteorological trends for the Pakistan region and more broadly serves to demonstrate the utility of the presented 30 arc-second monthly precipitation and mean temperature datasets for use in data scarce regions.

Mosier, T. M.; Hill, D. F.; Sharp, K. V.

2013-12-01

279

On the time-varying trend in global-mean surface temperature Zhaohua Wu Norden E. Huang John M. Wallace  

E-print Network

in the decades of the 1980s and 1990s (IPCC in Climate change 2007: the scientific basis, Cambridge University on Climate Change (IPCC 2007) fitted for different timescales, ranging from a warming trend of 0.045 ± 0-011-1128-8 #12;sometimes even negative trends centered around 1900 and 1950.1 These statistics serve

280

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

E-print Network

effects on the DTR. 1 Introduction The observed global mean trend towards warmer tem- peratures over land in soil moisture, mostly through its effect on the ground heat capacity. Both factors contribute about equally to the DTR trend. The exception to this relation occurs in the middle latitudes during winter

281

Non-linear thermal response of sandwich panels with a flexible core and temperature dependent mechanical properties  

Microsoft Academic Search

The paper presents the geometrical non-linear response of unidirectional sandwich panels with a “soft” core subjected to thermally induced deformation type of loading, which may be fully distributed or localized. The mathematical formulation incorporates the effects of the flexibility of the core in the vertical direction as well as the effects of the temperature dependent mechanical properties of the constituent

Yeoshua Frostig; Ole Thybo Thomsen

2008-01-01

282

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

283

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

284

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

285

INSTABILITY-DRIVEN LIMITS ON HELIUM TEMPERATURE ANISOTROPY IN THE SOLAR WIND: OBSERVATIONS AND LINEAR VLASOV ANALYSIS  

SciTech Connect

Kinetic microinstabilities in the solar wind arise when the plasma deviates too far from thermal equilibrium. Previously published work has provided strong evidence that the cyclotron, mirror, and parallel and oblique firehose instabilities limit proton (i.e., ionized hydrogen) temperature anisotropy. However, few studies have thoroughly explored whether a less-abundant ion species can also trigger these instabilities. This study considered the possibility of similar instability-driven limits on {alpha}-particle (i.e., fully ionized helium) temperature anisotropy. Linear Vlasov analysis was used to derive the expected threshold conditions for instabilities driven by {alpha}-particle temperature anisotropy. Measurements in situ of {alpha}-particle temperature anisotropy from the Wind spacecraft's Faraday cups were found to be consistent with the limits imposed by these instability thresholds. This strongly suggests that {alpha}-particles, which only constitute {approx}5% of ions in the solar wind, can drive an instability if their temperature anisotropy becomes sufficiently extreme.

Maruca, Bennett A.; Kasper, Justin C. [Department of Astronomy, Harvard University, Cambridge, MA 02138 (United States); Gary, S. Peter, E-mail: bmaruca@cfa.harvard.edu [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

2012-04-01

286

Spatial and Temporal Inter-Relationships Between Anomalies and Trends of Temperature, Moisture, Cloud Cover, and OLR as Observed by AIRS/AMSU on Aqua  

NASA Astrophysics Data System (ADS)

AIRS/AMSU is the advanced IR/MW atmospheric sounding system launched on EOS Aqua in May 2002. Products derived from AIRS/AMSU by the AIRS Science Team include surface skin temperature and atmospheric temperature profiles; atmospheric humidity profiles, fractional cloud cover and cloud top pressure, and OLR. Products covering the period September 2002 through the present have been derived from AIRS/AMSU using the AIRS Science Team Version 5 retrieval algorithm. In this paper, we will show results covering the time period September 2002- August 2008. This time period is marked by a substantial warming trend of Northern Hemisphere Extra-tropical land surface skin temperatures, as well as pronounced El Nino - La Nina episodes. These both influence the spatial and temporal anomaly patterns of atmospheric temperature and moisture profiles, as well as of cloud cover and Clear sky and All Sky OLR. The relationships between temporal and spatial anomalies of these parameters over this time period, as determined from AIRS/AMSU observations, will be shown, with particular emphasis on which contribute significantly to OLR anomalies in each of the tropics and extra-tropics. Results will also be shown to validate the anomalies and trends of temperature profiles, cloud cover, and OLR as determined from analysis of AIRS/AMSU data. Global and regional trends during the 6 year period shown are not necessarily indicative of what has happened in the past, or what may happen in the future. Nevertheless, the inter-relationships of spatial and temporal anomalies of atmospheric geophysical parameters with those of surface skin temperature are indicative of climate processes, and can be used to test the performance of climate models when driven by changes in surface temperatures.

Susskind, J.; Molnar, G.

2008-12-01

287

Spatial and Temporal Inter-Relationship between Anomalies and Trends of Temperature, Moisture, Cloud Cover and OLR as Observed by AIRS/AMSU on Aqua  

NASA Technical Reports Server (NTRS)

AIRS/AMSU is the advanced IR/MW atmospheric sounding system launched on EOS Aqua in May 2002. Products derived from AIRS/AMSU by the AIRS Science Team include surface skin temperature and atmospheric temperature profiled; atmospheric humidity profiles, fractional cloud clover and cloud top pressure, and OLR. Products covering the period September 2002 through the present have been derived from AIRS/AMSU using the AIRS Science Team Version 5 retrieval algorithm. In this paper, we will show results covering the time period September 2006 - November 2008. This time period is marked by a substantial warming trend of Northern Hemisphere Extra-tropical land surface skin temperatures, as well as pronounced El Nino - La Nina episodes. These both influence the spatial and temporal anomaly patterns of atmospheric temperature and moisture profiles, as well as of cloud cover and Clear Sky and All Sky OLR. The relationships between temporal and spatial anomalies of these parameters over this time period, as determined from AIRS/AMSU observations, will be shown with particular emphasis on which contribute significantly to OLR anomalies in each of the tropics and extra-tropics. Results will also be shown to evaluate the anomalies and trends of temperature profiles and OLR as determined from analysis of AIRS/AMSU data. Global and regional trends during the 6 1/3 year time period are not necessarily indicative of what has happened in the past, or what may happen in the future. Nevertheless, the inter-relationships of spatial and temporal anomalies of atmospheric geophysical parameters with those of surface skin temperature are indicative of climate processes, and can be used to test the performance of climate models when driven by changes in surface temperatures.

Susskind, Joel; Molnar, Gyula

2009-01-01

288

Spatial and Temporal Inter-Relationships between Anomalies and Trends of Temperature, Moisture, Cloud Cover, and OLR as Observed by AIRS/AMSU on Aqua  

NASA Technical Reports Server (NTRS)

AIRS/AMSU is the advanced IR/MW atmospheric sounding system launched on EOS Aqua in May 2002. Products derived from AIRS/AMSU by the AIRS Science Team include surface skin temperature and atmospheric temperature profiles; atmospheric humidity profiles, fractional cloud cover and cloud top pressure, and OLR. Products covering the period September 2002 through the present have been derived from AIRS/AMSU using the AIRS Science Team Version 5 retrieval algorithm. In this paper, we will show results covering the time period September 2006 - November 2008. This time period is marked by a substantial warming trend of Northern Hemisphere Extratropical land surface skin temperatures, as well as pronounced El Nino - La Nina episodes. These both influence the spatial and temporal anomaly patterns of atmospheric temperature and moisture profiles, as well as of cloud cover and Clear sky and All Sky OLR. The relationships between temporal and spatial anomalies of these parameters over this time period, as determined from AIRS/AMSU observations, will be shown, with particular emphasis on which contribute significantly to OLR anomalies in each of the tropics and extra-tropics. Results will also be shown to validate the anomalies and trends of temperature profiles and OLR as determined from analysis of AIRS/AMSU data. Global and regional trends during the 6 1/3 year period are not necessarily indicative of what has happened in the past, or what may happen in the future. Nevertheless, the inter-relationships of spatial and temporal anomalies of atmospheric geophysical parameters with those of surface skin temperature are indicative of climate processes, and can be used to test the performance of climate models when driven by changes in surface temperatures.

Susskind, Joel

2008-01-01

289

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

290

Trends in hemispheric warm and cold anomalies  

NASA Astrophysics Data System (ADS)

Using a spatial percentile approach, we explore the magnitude of temperature anomalies across the Northern and Southern Hemispheres. Linear trends in spatial percentile series are estimated for 1881-2013, the most recent 30 year period (1984-2013), and 1998-2013. All spatial percentiles in both hemispheres show increases from 1881 to 2013, but warming occurred unevenly via modification of cold anomalies, producing a reduction in spatial dispersion. In the most recent 30 year period, trends also were consistently positive, with warm anomalies having much larger warming rates than those of cold anomalies in both hemispheres. This recent trend has largely reversed the decrease in spatial dispersion that occurred during the twentieth century. While the period associated with the recent slowdown of global warming, 1998-2013, is too brief to estimate trends reliably, cooling was evident in NH warm and cold anomalies during January and February while other months in the NH continued to warm.

Robeson, Scott M.; Willmott, Cort J.; Jones, Phil D.

2014-12-01

291

Trend analysis of air temperature time series in Greece and their relationship with circulation using surface and satellite data: 1955–2001  

Microsoft Academic Search

Summary In this study, trends of annual and seasonal surface air temperature time series were examined for 20 stations in Greece for the period 1955–2001, and satellite data for the period 1980–2001. Two statistical tests based on the least square method and one based on the Mann-Kendall test, which is also capable of detecting the starting year of possible climatic

H. Feidas; T. Makrogiannis; E. Bora-Senta

2004-01-01

292

An intercomparison of observed and simulated extreme rainfall and temperature events during the last half of the twentieth century: part 2: historical trends  

Microsoft Academic Search

We analyze historical simulations of variability in temperature and rainfall extremes in the twentieth century, as derived\\u000a from various global models run informing the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC-AR4).\\u000a On the basis of three indices of climate extremes, we compare observed and modeled trends in time and space, including the\\u000a direction and significance of

Jose A. Marengo; Matilde Rusticucci; Olga Penalba; Madeleine Renom

2010-01-01

293

Monitoring the linear alkylbenzene sulfonation process using high-temperature gas chromatography  

Microsoft Academic Search

Controlling the linear alkylbenzene sulfonate (LAS) sulfonation process is a critical part of the LAS manufacturing process;\\u000a this process can be monitored by assaying for LAS content, unsulfonated linear alkylbenzene (LAB), and LAB sulfones. Traditionally,\\u000a assaying the LAB and LAB sulfone contents has been time consuming and not straightforward. A simple and rapid procedure is\\u000a described for the isolation and

K. Molever

2005-01-01

294

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...

295

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

296

The non-linear relationship between nerve conduction velocity and skin temperature  

Microsoft Academic Search

Median motor and sensory nerves were examined in 20 healthy subjects. Superficial stimulating and recording electrodes were used, and the nerves were examined at natural skin temperature, after cooling and after heating of the arm. The conduction velocity for the fastest and slow conducting sensory fibres (temperature range 17-37 degrees C), and for the fastest conducting motor fibres (temperature range

K Todnem; G Knudsen; T Riise; H Nyland; J A Aarli

1989-01-01

297

Protists decrease in size linearly with temperature: ca. 2.5%  C-1  

Microsoft Academic Search

An inverse relationship between organism size and rearing temperature is widely observed in ectotherms (' the temperature- size rule' , TSR). This has rarely been quantified for related taxa, and its applicability to protists also required testing. Here, we quantify the relationship between temperature and mean cell volume within the protists by a meta-analysis of published data covering marine, brackish

David Atkinson; Benjamin J. Ciotti; David J. S. Montagnes

2003-01-01

298

Nuclear matter properties in the non-linear Walecka model at finite temperature with interaction between the ? - ? mesons  

NASA Astrophysics Data System (ADS)

In this work in contrast to the usual Walecka model [1] we include the interaction between the ? - ? mesons [2,3] with the aim of studying the nuclear matter properties in the relativistic mean-field theory in the regime of high temperatures. Therefore in our work we use the non-linear Walecka model. We investigate whether the phase transition characteristic of other models without these interactions vanishes for a given value of chemical potential ? and baryon density ?N.

Costa, R. S.; Cortes, M. R.; Nunes, D. R.; Batista, A. S. A.

2014-11-01

299

Low-temperature phases obtained by linear programming: An application to a lattice system of model chiral molecules  

NASA Astrophysics Data System (ADS)

A convenient, Peierls-type approach to obtain low-temperature phases is to use the method of an m-potential. In this paper we show that, for more complex systems where it may be rather difficult to rewrite the Hamiltonian as an m-potential and whose configurations are subject to linear constraints, the verification of the Peierls condition can be reformulated as a linear programming problem. Before introducing this novel strategy for a general lattice system, we compare it with the m-potential method for a specific model molecular system consisting of an equimolar mixture of a chiral molecule and its non-superimposable mirror image that occupy all the sites of a honeycomb lattice. In one range of interactions, we prove that a racemic low-temperature phase occurs (containing equal numbers of each enantiomer). However, in a neighboring range of interactions, we show that a homochiral low-temperature phase (containing a single enantiomer) exists, and thus chiral segregation occurs in the system. Our linear programming technique yields these results in wider ranges of interactions than the m-potential method.

Medved', Igor; Trník, Anton; Huckaby, Dale A.

2011-09-01

300

Analysis of General Circulation Model Sea-Surface Temperature Anomaly Simulations Using a Linear Model. Part I: Forced Solutions.  

NASA Astrophysics Data System (ADS)

Experiments are presented which indicate that many features of the response of a general circulation model to sea-surface temperature anomalies in the equatorial Pacific east of the dateline can be reproduced with a linear nondivergent barotropic vorticity-conserving model. The midlatitude response to anomalous forcing is especially well reproduced by the simple model if it is linearized about the general circulation model's wavy control climatology. Diagnosis of the linear solutions using kinetic energy and enstrophy budget, as well as indicators of group velocity, indicates that basic state-perturbation interaction supplies nearly as much energy to the perturbation flow as anomalous forcing does.Further experiments show that the linear model is incapable of reproducing the finding of Geisler et al. that the structure of the general circulation model's midlatitude response is insensitive to the longitudinal position of the forcing anomaly. However, a Green's function analysis of the linear model points out that the midlatitude pattern which dominates the general circulation model experiments is very easily forced by anomalies over the East Indies. Thus it may be that anomalous precipitation in that region, caused by a weakening of the Walker circulation, is the primary impetus for the midlatitude flow anomalies.

Branstator, Grant

1985-11-01

301

Instability-Driven Limits on Ion Temperature Anisotropy in the Solar Wind: Observations and Linear Vlasov Theory  

NASA Astrophysics Data System (ADS)

Kinetic microinstabilities in the solar wind arise when its non-thermal properties become too extreme. This thesis project focused specifically on the four instabilities associated with ion temperature anisotropy: the cyclotron, mirror, and parallel and oblique firehose instabilities. Numerous studies have provided evidence that proton temperature anisotropy in the solar wind is limited by the actions of these instabilities. For this project, a fully revised analysis of data from the Wind spacecraft's Faraday cups and calculations from linear Vlasov theory were used to extend these findings in two respects. First, theoretical thresholds were derived for the alpha-particle temperature anisotropy instabilities, which were then found to be consistent with a statistical analysis of Wind alpha-particle data. This suggests that alpha-particles, which constitute only about 5% of ions in the solar wind, are nevertheless able to drive temperature anisotropy instabilities. Second, a statistical analysis of Wind proton data found that proton temperature was significantly enhanced in plasma unstable due to proton temperature anisotropy. This implies that extreme proton temperature anisotropies in solar wind at 1 AU arise from ongoing anisotropic heating (versus cooling from, e.g., CGL double adiabatic expansion). Together, these results provide further insight into the complex evolution of the solar wind's non-fluid properties.

Maruca, Bennett Andrew

302

Thirteen Years of Observations at Alaskan CALM Sites: Long-Term Active Layer and Ground Surface Temperature Trends  

Microsoft Academic Search

Active layer monitoring is an important component of efforts to assess the affects of global change in permafrost environments. In this study we used data from 13 (1995-2007) years of spatially oriented field observations at a series of 16 representative Circumpolar Active Layer Monitoring (CALM) sites in northern Alaska to examine temporal and spatial trends in active layer thickness and

Dmitry A. Streletskiy; Nikolay I. Shiklomanov; Frederick E. Nelson; Anna E. Klene

303

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

304

A non-linear effect of ambient temperature on apparent glucose tolerance  

Microsoft Academic Search

Increased ambient temperature affects apparent oral glucose tolerance to an extent which may have clinical implications for the diagnosis of impaired glucose tolerance and gestational diabetes. As a first step in order to better define the nature of this effect, we have examined, in a climate chamber, the effects of ambient temperature at four levels (20, 25, 30, and 35

R. G. Moses; M. J. Patterson; J. M. Regan; R. Chaunchaiyakul; N. A. S. Taylor; A. B. Jenkins

1997-01-01

305

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

306

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

307

On the statistical significance of climate trends  

NASA Astrophysics Data System (ADS)

One of the major problems in climate science is the prediction of future climate change due to anthropogenic green-house gas emissions. The earth's climate is not changing in a uniform way because it is a complex nonlinear system of many interacting components. The overall warming trend can be interrupted by cooling periods due to natural variability. Thus, in order to statistically distinguish between internal climate variability and genuine trends one has to assume a certain null model of the climate variability. Traditionally a short-range, and not a long-range, dependent null model is chosen. Here I show evidence for the first time that temperature data at 8 stations across Antarctica are long-range dependent and that the choice of a long-range, rather than a short-range, dependent null model negates the statistical significance of temperature trends at 2 out of 3 stations. These results show the short comings of traditional trend analysis and imply that more attention should be given to the correlation structure of climate data, in particular if they are long-range dependent. In this study I use the Empirical Mode Decomposition (EMD) to decompose the univariate temperature time series into a finite number of Intrinsic Mode Functions (IMF) and an instantaneous mean. While there is no unambiguous definition of a trend, in this study we interpret the instantaneous mean as a trend which is possibly nonlinear. The EMD method has been shown to be a powerful method for extracting trends from noisy and nonlinear time series. I will show that this way of identifying trends is superior to the traditional linear least-square fits.

Franzke, Christian

2010-05-01

308

Temperature and density mapping of supersonic jet expansions using linear Raman spectroscopy  

SciTech Connect

We present a first practical demonstration of Raman spectroscopy to obtain high definition maps of rotational temperatures and absolute densities in molecular supersonic jets. {copyright} {ital 1995 The American Physical Society.}

Tejeda, G.; Mate, B.; Fernandez-Sanchez, J.M.; Montero, S. [Instituto de Estructura de la Materia, Consejo Superior de Investigaciones Cientificas, Serrano 123, 28006 Madrid (Spain)] [Instituto de Estructura de la Materia, Consejo Superior de Investigaciones Cientificas, Serrano 123, 28006 Madrid (Spain)

1996-01-01

309

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

Microsoft Academic Search

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

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

2009-01-01

310

Comparing linear ion-temperature-gradient-driven mode stability of the National Compact Stellarator Experiment and a shaped tokamak  

SciTech Connect

One metric for comparing confinement properties of different magnetic fusion energy configurations is the linear critical gradient of drift wave modes. The critical gradient scale length determines the ratio of the core to pedestal temperature when a plasma is limited to marginal stability in the plasma core. The gyrokinetic turbulence code GS2 was used to calculate critical temperature gradients for the linear, collisionless ion temperature gradient (ITG) mode in the National Compact Stellarator Experiment (NCSX) and a prototypical shaped tokamak, based on the profiles of a JET H-mode shot and the stronger shaping of ARIES-AT. While a concern was that the narrow cross section of NCSX at some toroidal locations would result in steep gradients that drive instabilities more easily, it is found that other stabilizing effects of the stellarator configuration offset this so that the normalized critical gradients for NCSX are competitive with or even better than for the tokamak. For the adiabatic ITG mode, NCSX and the tokamak had similar adiabatic ITG mode critical gradients, although beyond marginal stability, NCSX had larger growth rates. However, for the kinetic ITG mode, NCSX had a higher critical gradient and lower growth rates until a/L{sub T} Almost-Equal-To 1.5 a/L{sub T,crit}, when it surpassed the tokamak's. A discussion of the results presented with respect to a/L{sub T} vs. R/L{sub T} is included.

Baumgaertel, J. A. [Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States); Hammett, G. W.; Mikkelsen, D. R. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

2013-02-15

311

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

E-print Network

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

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

2008-08-05

312

Quasi-linear theory of electron density and temperature fluctuations with application to MHD generators and MPD arc thrusters.  

NASA Technical Reports Server (NTRS)

Fluctuations in electron density and temperature coupled through Ohm's law are studied for an ionizable medium. The nonlinear effects are considered in the limit of a third order quasi-linear treatment. Equations are derived for the amplitude of the fluctuation. Conditions under which a steady state can exist in the presence of the fluctuation are examined and effective transport properties are determined. A comparison is made to previously considered second order theory. The effect of third order terms indicates the possibility of fluctuations existing in regions predicted stable by previous analysis.

Smith, J. M.

1972-01-01

313

Quasi-continuous-time impurity solver for the dynamical mean-field theory with linear scaling in the inverse temperature.  

PubMed

We present an algorithm for solving the self-consistency equations of the dynamical mean-field theory (DMFT) with high precision and efficiency at low temperatures. In each DMFT iteration, the impurity problem is mapped to an auxiliary Hamiltonian, for which the Green function is computed by combining determinantal quantum Monte Carlo (BSS-QMC) calculations with a multigrid extrapolation procedure. The method is numerically exact, i.e., yields results which are free of significant Trotter errors, but retains the BSS advantage, compared to direct QMC impurity solvers, of linear (instead of cubic) scaling with the inverse temperature. The new algorithm is applied to the half-filled Hubbard model close to the Mott transition; detailed comparisons with exact diagonalization, Hirsch-Fye QMC, and continuous-time QMC are provided. PMID:23767655

Rost, D; Assaad, F; Blümer, N

2013-05-01

314

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

315

Quasi-continuous-time impurity solver for the dynamical mean-field theory with linear scaling in the inverse temperature  

NASA Astrophysics Data System (ADS)

We present an algorithm for solving the self-consistency equations of the dynamical mean-field theory (DMFT) with high precision and efficiency at low temperatures. In each DMFT iteration, the impurity problem is mapped to an auxiliary Hamiltonian, for which the Green function is computed by combining determinantal quantum Monte Carlo (BSS-QMC) calculations with a multigrid extrapolation procedure. The method is numerically exact, i.e., yields results which are free of significant Trotter errors, but retains the BSS advantage, compared to direct QMC impurity solvers, of linear (instead of cubic) scaling with the inverse temperature. The new algorithm is applied to the half-filled Hubbard model close to the Mott transition; detailed comparisons with exact diagonalization, Hirsch-Fye QMC, and continuous-time QMC are provided.

Rost, D.; Assaad, F.; Blümer, N.

2013-05-01

316

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

317

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

318

Thermal radiation fields in time-dependent linear media at finite temperature  

NASA Astrophysics Data System (ADS)

The properties of thermal radiation fields in linear media which have time-dependent parameters are investigated on the basis of the invariant operator method. For quantum mechanical description of the electromagnetic waves whose amplitude and/or frequency vary with time, we introduce a quadratic invariant operator that is constructed according to its exact definition. The density operator of the system, being considered signal plus noise, is obtained via maximization of the entropy. The expectation values of the energy operator, the Hamiltonian, and the invariant operator are obtained in the thermal state and their thermal behaviours are illustrated in detail. It is shown that the fluctuations of the electric and the magnetic fields do not depend on signal plus noise and dissipate with time due to the conductivity in media. Our theory of wave propagation in time-varying media is applied to describe the biophoton signal in order to promote the understanding of our developments.

Ryeol Choi, Jeong

2013-10-01

319

Disturbances of temperature-depth profiles due to surface climate change and subsurface water flow: 1. An effect of linear increase in surface temperature caused by global warming and urbanization in the Tokyo metropolitan area, Japan  

Microsoft Academic Search

A series of type curves is presented for evaluating vertical groundwater fluxes under the condition of a linear increase in surface temperature. The depths of minimum groundwater temperature in the temperature-depth profiles indicate the magnitude of the downward groundwater flux. The type curve method has been applied to the subsurface thermal regime observed in Tokyo metropolitan area, Japan, to estimate

Makato Taniguchi; Jun Shimada; Tadashi Tanaka; Isamu Kayane; Yasuo Sakura; Yasuo Shimano; S. Dapaah-Siakwan; Shinichi Kawashima

1999-01-01

320

Cold-season temperature in the Swiss Alps from AD 1100-1500; trends, intra-annual variability and forcing factors  

NASA Astrophysics Data System (ADS)

To fully understand past climatic changes and their forcing factors, detailed reconstructions of past summer and winter temperatures are required. Winter temperature reconstructions are scarce, however, because most biological proxies are biased towards the growing season. This study presents a detailed reconstruction of winter temperatures based on Chrysophyte stomatocysts, silicious scales formed by so-called 'golden algae'. Previous studies (Kamenik and Schmidt, 2005; Pla and Catalan, 2005) have demonstrated the sensitivity of these algae to cold-season temperatures. Chrysophyte stomatocyst analysis was carried out on varved sediments from Lake Silvaplana (1791 m a.s.l.) at annual to near-annual resolution for two periods; AD 1100-1500 and AD 1870-2004. For both periods the reference date 'date of spring mixing' (Smix) was reconstructed using a transfer function developed for the Austrian Alps (Kamenik and Schmidt, 2005). In the Austrian Alps, Smix was primarily driven by air temperature in the cold season. The strength of stomatocysts as a proxy for winter temperature was tested by directly comparing reconstructed Smix with measured temperatures from nearby meteostation Sils Maria for the period AD 1870 - 2004. Correlation was highest (R = -0.6; p < 0.001) with mean October-April temperatures. The good agreement between reconstructed Smix and mean winter temperatures was interrupted only from AD 1925 - AD 1951, which was related to exceptionally high winter precipitation (thick snowpack) extending the ice-covered period. Strong lake eutrophication after AD 1950 only weakly affected the reconstruction of winter temperature. The winter temperature reconstruction (AD 1100-1500) shows strong interdecadal variability, superimposed on a cooling trend from around AD 1400 onwards. A direct comparison to summer temperature reconstructions based on biogenic silica and chironomid analysis from the same cores (Trachsel et al., in review; Larocque-Tobler et al., accepted manuscript) indicated strong fluctuations in intra-annual variability. A comparison to forcing factors shows that throughout the studied period, large tropical volcanic eruptions (Crowley, 2000) coincided with relatively warm winters in the study area. This is consistent with results from GCM experiments and observations of the limited number of eruptions during the much shorter instrumental period (Fischer et al., 2007). References: T. Crowley. Science 289, 270-277 (2000) E. Fischer et al. Geophys. Res. Lett. 34, L05707 (2007) C. Kamenik and R. Schmidt. Boreas 34, 477-489 (2005) I. Larocque-Tobler et al. Quat. Sci. Rev., accepted. S. Pla and J. Catalan. Clim. Dyn. 24, 263-278 (2005) M. Trachsel et al. Manuscript in review

de Jong, Rixt; Kamenik, Christian; Grosjean, Martin

2010-05-01

321

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

322

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

323

Comparison of kinetic and extended magnetohydrodynamics computational models for the linear ion temperature gradient instability in slab geometry  

SciTech Connect

We perform linear stability studies of the ion temperature gradient (ITG) instability in unsheared slab geometry using kinetic and extended magnetohydrodynamics (MHD) models, in the regime k{sub ?}/k{sub ?}?1. The ITG is a parallel (to B) sound wave that may be destabilized by finite ion Larmor radius (FLR) effects in the presence of a gradient in the equilibrium ion temperature. The ITG is stable in both ideal and resistive MHD; for a given temperature scale length L{sub Ti0}, instability requires that either k{sub ?}?{sub i} or ?{sub i}/L{sub Ti0} be sufficiently large. Kinetic models capture FLR effects to all orders in either parameter. In the extended MHD model, these effects are captured only to lowest order by means of the Braginskii ion gyro-viscous stress tensor and the ion diamagnetic heat flux. We present the linear electrostatic dispersion relations for the ITG for both kinetic Vlasov and extended MHD (two-fluid) models in the local approximation. In the low frequency fluid regime, these reduce to the same cubic equation for the complex eigenvalue ?=?{sub r}+i?. An explicit solution is derived for the growth rate and real frequency in this regime. These are found to depend on a single non-dimensional parameter. We also compute the eigenvalues and the eigenfunctions with the extended MHD code NIMROD, and a hybrid kinetic ?f code that assumes six-dimensional Vlasov ions and isothermal fluid electrons, as functions of k{sub ?}?{sub i} and ?{sub i}/L{sub Ti0} using a spatially dependent equilibrium. These solutions are compared with each other, and with the predictions of the local kinetic and fluid dispersion relations. Kinetic and fluid calculations agree well at and near the marginal stability point, but diverge as k{sub ?}?{sub i} or ?{sub i}/L{sub Ti0} increases. There is good qualitative agreement between the models for the shape of the unstable global eigenfunction for L{sub Ti0}/?{sub i}=30 and 20. The results quantify how far fluid calculations can be extended accurately into the kinetic regime. We conclude that for the linear ITG problem in slab geometry with unsheared magnetic field when k{sub ?}/k{sub ?}?1, the extended MHD model may be a reliable physical model for this problem when ?{sub i}/L{sub Ti0}<10{sup ?2} and k{sub ?}?{sub i}<0.2.

Schnack, D. D. [Department of Engineering Physics, Center for Plasma Theory and Computation, University of Wisconsin—Madison, Madison, Wisconsin 53706 (United States) [Department of Engineering Physics, Center for Plasma Theory and Computation, University of Wisconsin—Madison, Madison, Wisconsin 53706 (United States); Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Cheng, J.; Parker, S. E. [Department of Physics, University of Colorado-Boulder, Boulder, Colorado 80303 (United States)] [Department of Physics, University of Colorado-Boulder, Boulder, Colorado 80303 (United States); Barnes, D. C. [TriAlpha Energy, Inc., P. O. Box 7010, Rancho Santa Margarita, California 92688 (United States)] [TriAlpha Energy, Inc., P. O. Box 7010, Rancho Santa Margarita, California 92688 (United States)

2013-06-15

324

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

E-print Network

of the most prominent and important features of climate change is that surface air temperature (SAT) change have had considerable influence on the Arctic warm- ing during the boreal winter. During that time localized tropical heating, are fol- lowed 1­2 weeks later by Arctic warming. Similarly, MJO phases 1

Lee, Sukyoung

325

Ion temperature profile stiffness: non-linear gyrokinetic simulations and comparison with experiment  

NASA Astrophysics Data System (ADS)

Recent experimental observations at JET show evidence of reduced ion temperature profile stiffness. An extensive set of nonlinear gyrokinetic simulations are performed based on the experimental discharges, investigating the physical mechanism behind the observations. The impact on the ion heat flux of various parameters that differ within the data-set are explored. These parameters include the safety factor, magnetic shear, toroidal flow shear, effect of rotation on the magnetohydrodynamic equilibrium, R/Ln, ?e, Zeff, Te/Ti, and the fast-particle content. While previously hypothesized to be an important factor in the stiffness reduction, the combined effect of toroidal flow shear and low magnetic shear is not predicted by the simulations to lead to a significant reduction in ion heat flux, due both to an insufficient magnitude of flow shear and significant parallel velocity gradient destabilization. It is however found that nonlinear electromagnetic effects due to both thermal and fast-particle pressure gradients, even at low ?e, can significantly reduce the ion heat flux, and is a key factor in explaining the experimental observations. A total of four discharges are examined, at both inner and outer radii. For all cases studied, the simulated and experimental ion heat flux values agree within reasonable variations of input parameters around the experimental uncertainties.

Citrin, J.; Jenko, F.; Mantica, P.; Told, D.; Bourdelle, C.; Dumont, R.; Garcia, J.; Haverkort, J. W.; Hogeweij, G. M. D.; Johnson, T.; Pueschel, M. J.; contributors, JET-EFDA

2014-02-01

326

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

E-print Network

the Gulf of Mexico near the Yucatan Peninsula is transported northward as a result of a persistent weather pattern (Dirmeyer and Kinter, 2009). Although it is not clear whether these later mechanisms can be simulated in a GCM, we propose to assess how GCMs...., 1998). Compounding the effects of air temperature and water use impacts under global warming scenarios is the biological control exhibited by vegetation. It is generally proposed that there is a positive feedback between climatic warming and biospheric...

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

2009-01-08

327

The impact of the Madden-Julian Oscillation trend on the Arctic amplification of surface air temperature during the 1979-2008 boreal winter  

NASA Astrophysics Data System (ADS)

One of the most prominent and important features of climate change is that surface air temperature (SAT) change is greatest at high latitudes. The cause for this Arctic amplification of SAT is uncertain. Using ERA-Interim reanalysis data, we show that Arctic amplification during the past 30 years (1979 to 2008) is linked to the Madden-Julian Oscillation (MJO), the primary mode of intraseasonal variability in the tropics. Specifically, it is shown that interdecadal changes in the frequency of occurrence of individual MJO phases have had considerable influence on the Arctic warming during the boreal winter. During that time period, MJO phases 4-6 exhibited a large increase and phases 1-2 a moderate decrease in their frequency of occurrence. Time lagged composites of the SAT show that MJO phases 4-6, which correspond to enhanced localized tropical heating, are followed 1-2 weeks later by Arctic warming. Similarly, MJO phases 1-2, which are associated with more zonally uniform tropical heating, are followed by Arctic cooling. These relationships between the Arctic SAT and the spatial structure of the tropical heating are consistent with the poleward propagation mechanism of Lee et al. (2011a, 2011b). By incorporating both the trend in MJO phase and the intraseasonal SAT anomaly associated with the MJO, it was found that the MJO-induced SAT trend accounts for 10-20% of the observed Arctic amplification over the Arctic Ocean.

Yoo, Changhyun; Feldstein, Steven; Lee, Sukyoung

2011-12-01

328

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

329

Adsorption of linear alkanes on Cu(111): Temperature and chain-length dependence of the softened vibrational mode  

NASA Astrophysics Data System (ADS)

The vibrational spectra of linear alkanes, with lengths ranging from n-propane to n-octane, were examined on a copper surface by reflection-absorption infrared spectroscopy. The appearance and frequency of the "soft mode," a feature routinely seen in studies of saturated hydrocarbons adsorbed on metals, were examined and compared between the different adsorbates. The frequency of the mode was found to be dependent on both the number of methylene units of each alkane as well as specific aspects of the order of the monolayer phase. Studies of monolayer coverages at different temperatures provide insights into the nature of the two-dimensional (2D) melting transitions of these adlayer structures, ones that can be inferred from observed shifts in the soft vibrational modes appearing in the C-H stretching region of the infrared spectrum. These studies support recently reported hypotheses as to the origins of such soft modes: the metal-hydrogen interactions that mediate them and the dynamics that underlay their pronounced temperature dependencies. The present data strongly support a model for the 2D to one-dimensional order-order phase transition arising via a continuous rather than discrete first-order process.

Fosser, Kari A.; Kang, Joo H.; Nuzzo, Ralph G.; Wöll, Christof

2007-05-01

330

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

331

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

332

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

SciTech Connect

Mechanical properties and glass transition temperatures (T{sub g}) of Fe-Cr-Mo-P-C-B bulk metallic glasses containing up to 27 at. % metalloids have been studied. The shear modulus (G) is found to decrease with increasing metalloid content and a maximum plastic strain of {approx}3% is obtained, despite the increase in the number of strong metal-metalloid bonds. Also, T{sub g} increases with the decrease in G, in contrast to usual behavior. By employing first-principles calculations, the results are discussed in light of atomic bonding and connectivity in the amorphous network. The findings are relevant to understanding ductility and glass transition of metallic glasses.

Gu, X. J.; Poon, S. Joseph [Department of Physics, University of Virginia, Charlottesville, Virginia 22904-4714 (United States); Shiflet, Gary J. [Department of Materials Science and Engineering, University of Virginia, Charlottesville, Virginia 22904-4745 (United States); Widom, Michael [Department of Physics, Carnegie Mellon University, Pittsburgh, Philadelphia, Pennsylvania 15213 (United States)

2008-04-21

333

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

334

Trend analysis of the long-term Swiss ozone measurements  

NASA Technical Reports Server (NTRS)

Trend analyses, assuming a linear trend which started at 1970, were performed from total ozone measurements from Arosa (Switzerland, 1926-1991). Decreases in monthly mean values were statistically significant for October through April showing decreases of about 2.0-4 percent per decade. For the period 1947-91, total ozone trends were further investigated using a multiple regression model. Temperature of a mountain peak in Switzerland (Mt. Santis), the F10.7 solar flux series, the QBO series (quasi biennial oscillation), and the southern oscillation index (SOI) were included as explanatory variables. Trends in the monthly mean values were statistically significant for December through April. The same multiple regression model was applied to investigate the ozone trends at various altitudes using the ozone balloon soundings from Payerne (1967-1989) and the Umkehr measurements from Arosa (1947-1989). The results show four different vertical trend regimes: On a relative scale changes were largest in the troposphere (increase of about 10 percent per decade). On an absolute scale the largest trends were obtained in the lower stratosphere (decrease of approximately 6 per decade at an altitude of about 18 to 22 km). No significant trends were observed at approximately 30 km, whereas stratospheric ozone decreased in the upper stratosphere.

Staehelin, Johannes; Bader, Juerg; Gelpke, Verena

1994-01-01

335

Century-scale trends and seasonality in pH and temperature for shallow zones of the Bering Sea.  

PubMed

No records exist to evaluate long-term pH dynamics in high-latitude oceans, which have the greatest probability of rapid acidification from anthropogenic CO2 emissions. We reconstructed both seasonal variability and anthropogenic change in seawater pH and temperature by using laser ablation high-resolution 2D images of stable boron isotopes (?(11)B) on a long-lived coralline alga that grew continuously through the 20th century. Analyses focused on four multiannual growth segments. We show a long-term decline of 0.08 ± 0.01 pH units between the end of the 19th and 20th century, which is consistent with atmospheric CO2 records. Additionally, a strong seasonal cycle (?0.22 pH units) is observed and interpreted as episodic annual pH increases caused by the consumption of CO2 during strong algal (kelp) growth in spring and summer. The rate of acidification intensifies from -0.006 ± 0.007 pH units per decade (between 1920s and 1960s) to -0.019 ± 0.009 pH units per decade (between 1960s and 1990s), and the episodic pH increases show a continuous shift to earlier times of the year throughout the centennial record. This is indicative of ecosystem shifts in shallow water algal productivity in this high-latitude habitat resulting from warming and acidification. PMID:25713385

Fietzke, Jan; Ragazzola, Federica; Halfar, Jochen; Dietze, Heiner; Foster, Laura C; Hansteen, Thor Henrik; Eisenhauer, Anton; Steneck, Robert S

2015-03-10

336

Long-term trends in sea surface temperature in coastal water in relation to large-scale climate change: A case study in Omura Bay, Japan  

NASA Astrophysics Data System (ADS)

Long-term trends in sea surface temperature (SST) in Omura Bay were investigated using heat balance estimates based on a daily data set obtained for 40 years (1955-1995) by the National Pearl Research Laboratory. SST during the heating period (from March to August) tended to decrease, whereas that during most of the cooling period (from September to February) increased during these 40 years. The maximum rates of SST decrease and increase were found to be 0.020 °C year-1 in August and 0.028 °C year-1 in January, respectively. The sea surface heat balance analysis revealed that shortwave radiation flux decreased in the heating period due to decrease in solar radiation, resulting in a decrease in SST. In the cooling period, the increase in SST was attributed to the decrease in latent and sensible heat fluxes due to increased air temperature and decreased wind speed. These climatic changes affecting SST in Omura Bay showed a close linkage with global dimming and the East Asian monsoon circulation.

Takeshige, Aigo; Takahashi, Tetsuya; Nakata, Hideaki; Kimura, Shingo

2013-09-01

337

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

338

Techniques for analyses of trends in GRUAN data  

NASA Astrophysics Data System (ADS)

The Global Climate Observing System (GCOS) Reference Upper Air Network (GRUAN) provides reference quality RS92 radiosonde measurements of temperature, pressure and humidity. A key attribute of reference quality measurements, and hence GRUAN data, is that each datum has a well characterised and traceable estimate of the measurement uncertainty. The long-term homogeneity of the measurement records, and their well characterised uncertainties, make these data suitable for reliably detecting changes in global and regional climate on decadal time scales. Considerable effort is invested in GRUAN operations to (i) describe and analyse all sources of measurement uncertainty to the extent possible, (ii) quantify and synthesize the contribution of each source of uncertainty to the total measurement uncertainty, and (iii) verify that the evaluated net uncertainty is within the required target uncertainty. However, if the climate science community is not sufficiently well informed on how to capitalize on this added value, the significant investment in estimating meaningful measurement uncertainties is largely wasted. This paper presents and discusses the techniques that will need to be employed to reliably quantify long-term trends in GRUAN data records. A pedagogical approach is taken whereby numerical recipes for key parts of the trend analysis process are explored. The paper discusses the construction of linear least squares regression models for trend analysis, boot-strapping approaches to determine uncertainties in trends, dealing with the combined effects of autocorrelation in the data and measurement uncertainties in calculating the uncertainty on trends, best practice for determining seasonality in trends, how to deal with co-linear basis functions, and interpreting derived trends. Synthetic data sets are used to demonstrate these concepts which are then applied to a first analysis of temperature trends in RS92 radiosonde upper air soundings at the GRUAN site at Lindenberg, Germany (52.21° N, 14.12° E).

Bodeker, G. E.; Kremser, S.

2014-12-01

339

Continuous deflation and plate spreading at the Askja volcanic system, Iceland: Constrains on deformation processes from finite element models using temperature-dependent non-linear rheology  

NASA Astrophysics Data System (ADS)

Iceland is located on the mid Atlantic ridge, where the spreading rate is nearly 2 cm/yr. The high rate of magmatism in Iceland is caused by the interaction between the Iceland hotspot and the divergent mid-Atlantic plate boundary. Iceland hosts about 35 volcanoes or volcanic systems that are active. Most of these are aliened along the plate boundary. The best studied magma chamber of central volcanoes (e.g., Askja, Krafla, Grimsvötn, Katla) have verified (suggested) a shallow magma chamber (< 5 km), which has been model successfully with a Mogi source, using elastic and/or elastic-viscoelastic half-space. Maxwell and Newtonian viscosity is mainly considered for viscoelastic half-space. Therefore, rheology may be oversimplified. Our attempt is to study deformation of the Askja volcano together with plate spreading in Iceland using temperature-dependent non-linear rheology. It offers continuous variation of rheology, laterally and vertically from rift axis and surface. To implement it, we consider thermo-mechanic coupling models where rheology follows dislocation flow in dry condition based on a temperature distribution. Continuous deflation of the Askja volcanic system is associated with solidification of magma in the magma chamber and post eruption relaxation. A long time series of levelling data show its subsidence trend to exponentially. In our preliminary models, a magma chamber at 2.8 km depth with 0.5 km radius is introduced at the ridge axis as a Mogi source. Simultaneously far field of rift axis stretching by 18.4 mm/yr (measured during 2007 to 20013) is applied to reproduce plate spreading. Predicted surface deformation caused of combined effect of tectonic-volcanic activities is evaluated with GPS during 2003-2009 and RADARSAT InSAR data during 2000 to 2010. During 2003-2009, data from the GPS site OLAF (close to the centre of subsidence) shows average rate of subsidence 19±1 mm/yr relative to the ITRF2005 reference frame. The MASK (Mid ASKJA) site is another GPS station at the top of predicted centre of magma chamber correlates well with OLAF site at 500 m distance from MASK. Average subsidence rates derived from GPS measurements show comparable rate derived from InSAR data. Velocities derived from InSAR show that the yearly maximum subsidence rates in the Askja caldera decrease linearly. The optimized pressure decrease in the magma chamber from the model follows an exponential decay, with P (MPa) = 2.0177 EXP(-0.0176x), where x is the numbers of years (1,2,3 .. 10). However total ramp pressure drop during this period (10 years) is 4 MPa and additional 4.68 MPa pressure drop may be caused of rheological relaxation.

Tariqul Islam, Md.; Sturkell, Erik; Sigmundsson, Freysteinn; Drouin, Vincent Jean Paul B.; Ófeigsson, Benedikt G.

2014-05-01

340

Motion induced second order temperature and y-type anisotropies after the subtraction of linear dipole in the CMB maps  

SciTech Connect

y-type spectral distortions of the cosmic microwave background allow us to detect clusters and groups of galaxies, filaments of hot gas and the non-uniformities in the warm hot intergalactic medium. Several CMB experiments (on small areas of sky) and theoretical groups (for full sky) have recently published y-type distortion maps. We propose to search for two artificial hot spots in such y-type maps resulting from the incomplete subtraction of the effect of the motion induced dipole on the cosmic microwave background sky. This dipole introduces, at second order, additional temperature and y-distortion anisotropy on the sky of amplitude few ?K which could potentially be measured by Planck HFI and Pixie experiments and can be used as a source of cross channel calibration by CMB experiments. This y-type distortion is present in every pixel and is not the result of averaging the whole sky. This distortion, calculated exactly from the known linear dipole, can be subtracted from the final y-type maps, if desired.

Sunyaev, Rashid A.; Khatri, Rishi, E-mail: sunyaev@mpa-garching.mpg.de, E-mail: khatri@mpa-garching.mpg.de [Max Planck Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85741 Garching (Germany)

2013-03-01

341

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

342

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

343

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

344

Increasing the upper-limit intensity in relativistic and ponderomotive self-focusing by using plasma with a linear electron temperature ramp  

NASA Astrophysics Data System (ADS)

This paper presents an investigation of the characteristics of the propagation of a Gaussian laser beam through an underdense plasma in the presence of a linear electron temperature ramp. Relativistic and ponderomotive nonlinearities are involved. It is shown that the ponderomotive nonlinearity induces a saturation mechanism in the self-focusing phenomenon and leads to the existence of a laser intensity threshold above which the beam starts to diverge. It is also found that on using the plasma electron temperature ramp-up, the upper-limit value shifts to higher values. Furthermore, results show that the slope of the temperature ramp and its sign are important in the determination of the focusing and defocusing of a laser beam for the cases in which the initial electron temperatures are chosen below or above the turning point temperature.

Bokaei, B.; Niknam, A. R.; Jafari Milani, M. R.

2014-12-01

345

High Temperatures & Electricity Demand  

E-print Network

High Temperatures & Electricity Demand An Assessment of Supply Adequacy in California Trends.......................................................................................................1 HIGH TEMPERATURES AND ELECTRICITY DEMAND.....................................................................................................................7 SECTION I: HIGH TEMPERATURES AND ELECTRICITY DEMAND ..........................9 BACKGROUND

346

Design, prototyping, and testing of an apparatus for establishing a linear temperature gradient in experimental fish tanks  

E-print Network

Immunology researchers require a new type of fish tank that provides a linear thermal gradient for experimental zebrafish in order to improve the accuracy and validity of their research. Zebrafish require the ability to ...

Kadri, Romi Sinclair

2014-01-01

347

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

348

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

349

Monetary Trends  

NSDL National Science Digital Library

Each month, Monetary Trends , from FRB St. Louis, follows interest rates, bank credit, measures of expected inflation, and reserve markets and short-term credit flows. The journal examines interest rates and policy-based inflation indicators in its December 1999 issue.

350

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.

351

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

352

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 Aurélio Bomfim; VITTI, Rafael Pino; CONSANI, Simonides; SINHORETI, Mário Alexandre Coelho; MESQUITA, Marcelo Ferraz; CONSANI, Rafael Leonardo Xediek

2012-01-01

353

Monthly time series trend analysis of temperature and precipitation in North Carolina Authors: Mohammad Sayemuzzaman1; Manoj K Jha2 1Presenting author: PhD candidate, Energy and Environmental System department, 2Assistant Professor, Department of Civil, Architectural and Environmental Engineering, North Carolina A&T State University  

NASA Astrophysics Data System (ADS)

Abstract This study analyzed monthly means of daily maximum temperature (Tmax), minimum temperature (Tmin) and precipitation of 249 meteorological stations evenly distributed in North Carolina for the period of 1950-2009. The Mann-Kendall (MK) trend test was applied to examine the monthly trends over the period. Theil-Sen approach (TSA) was used to detect the magnitude of the trend. Finally, the abrupt shift in trends was also predicted using the Sequential Mann-Kendall (SQMK) test. Moreover, Pre-whitening was considered prior to the application of the MK test and the TSA method as the data sets were serially correlated. The number of stations (in %) with most significant trend (confidence level ? 95%) in highest impacted months are for (1) Tmax with negative trend: May (62%), September (25%) and October (18%); (2) Tmax with positive trend: March (15%); (3) Tmin with positive trend: June (45%), August (39%), December (25%) and July (21%); (4) Tmin with negative trend: May (18%); (5) precipitation with negative trend: February (17%) and March (4%); and (6) precipitation with positive trend: November (4%) and June (2%). It is found that month of May (March and December) are being exhibiting significant decreasing (increasing) trends in both Tmax and Tmin analysis. Magnitude of the highest warming trend in minimum temperature and the highest cooling trend in maximum temperature is +0.073°C/month in June and -0.12°C/month in September, respectively. The SQMK test results indicated that the significant increasing trends in Tmin and decreasing trend in Tmax had begun in general around after 1970 and after 1960, respectively, in most of the stations. Similarly, magnitude of the highest increasing (decreasing) precipitation trend was found about 4 mm/month (-4.50 mm/month) in November (February). Higher percentages of precipitation stations show possible year of trend shift during decade 1960~1970 in the SQMK test. It is expected that utilizing the findings of this study will bring about more insights for understanding of regional temperature and precipitation behavior over the last several decades in North Carolina.

Sayemuzzaman, M.; Jha, M. K.

2013-12-01

354

Temperature for the (2+1)-dimensional Black Hole with Non Linear Electrodynamics from the Generalized Uncertainty Principle  

E-print Network

In this paper, we study the thermodynamical properties of the (2+1) dimensional black hole with a non-linear electrodynamics and with a negative cosmological constant, using the Generalized Uncertainty Principle (GUP). This approach shows that there is a minimum mass or remnant for the black hole, corresponding to the minimum radius of the event horizon that has a size of the order of the Planck scale. We also show that the heat capacity for this black hole is always positive.

Alexis Larranaga; Hector J. Hortua

2009-01-23

355

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

356

Trends and Controls on Summer Surface-Water Temperatures in Salmonid-Bearing Headwater Streams in Two Common Geomorphic Settings, Kenai Peninsula, Alaska  

Microsoft Academic Search

Stream temperature is an important physical characteristic of headwater streams that plays a critical role in the presence and health of juvenile salmonids. Headwater stream temperature was documented in two geomorphic settings on the Kenai Peninsula, Alaska, focusing on the variation in temperature induced by diffuse groundwater discharge and variable air temperature. Eighteen headwater stream reaches were studied in four

M. K. Callahan; J. C. Bellino; M. C. Rains

2010-01-01

357

Non-linear absorption of 1.3-?m wavelength femtosecond laser pulses focused inside semiconductors: Finite difference time domain-two temperature model combined computational study  

NASA Astrophysics Data System (ADS)

We present a theoretical model, which describes local energy deposition inside IR-transparent silicon and gallium arsenide with focused 1.3-?m wavelength femtosecond laser pulses. Our work relies on the ionization rate equation and two temperature model (TTM), as we simulate the non-linear propagation of focused femtosecond light pulses by using a 3D finite difference time domain method. We find a strong absorption dependence on the initial free electron density (doping concentration) that evidences the role of avalanche ionization. Despite an influence of Kerr-type self-focusing at intensity required for non-linear absorption, we show the laser energy deposition remains confined when the focus position is moved down to 1-mm below the surface. Our simulation results are in agreement with the degree of control observed in a simple model experiment.

Bogatyrev, I. B.; Grojo, D.; Delaporte, P.; Leyder, S.; Sentis, M.; Marine, W.; Itina, T. E.

2011-11-01

358

Intermediate phase, network demixing, boson and floppy modes, and compositional trends in glass transition temperatures of binary AsxS1-x system  

E-print Network

by the proportionately larger free volumes of sulfides than selenides and the absence of chemical bond-strength scalingIntermediate phase, network demixing, boson and floppy modes, and compositional trends in glass manuscript received 13 November 2008; published 30 December 2008 The structure of binary AsxS1-x glasses

Boolchand, Punit

359

Spatial distribution and temporal trends of extreme temperature and precipitation events on the Loess Plateau of China during 1961-2007  

Technology Transfer Automated Retrieval System (TEKTRAN)

Extreme climate events often cause catastrophic damage to nature and human society. Therefore, regional assessments in various climate and geographic regions are needed for understanding the uncertainties in the changing trends for extreme climate events. The objective of this study was to assess th...

360

Temperature  

NSDL National Science Digital Library

This topic in depth begins with the About Temperature (1) Web site, written by Beverly T. Lynds of Unidata, which is a program that works to enable university researchers and educators to acquire and use atmospheric and related data. The one-page site explains what temperature is, the development of thermometers, heat and thermodynamics, and other related topics. The second site is maintained by the University of Execter's Centre for Innovation in Mathematics Teaching. Actually an online tool called Conversion Calculator for Units of Temperature (2), the site allows users to type in any value, choose a significant figure, press "convert it," and get that value in Kelvin, Celsius, Fahrenheit, r'aumur, and rankine units. The next site is a lesson plan from AskEric.com entitled Temperature: Is it Hot or Cold? (3). Written for 2nd graders, the lesson demonstrates to how to read thermometers, determine their rise or fall, record temperatures, and take temperatures of various items. The fourth site, Surface Temperature Analysis (4), is presented by NASA's Goddard Institute for Space Studies. Here, visitors can view graphs, maps, animations, and station data of global surface temperatures. For example, the animation covers 12-month means from 1971 to 1999. The History Behind the Thermometer (5) Web site, from About.com, explores what a thermometer is, how it works, and how it came into being. The sixth site, entitled Science Shack (6) and offered by the BBC, answers the question, Why do we have two different temperature scales, Celsius and Fahrenheit? The site explains how to create your own thermometer like Galileo's, tells how it works, and why we use other types today. The next site is provided by National Oceanic and Atmospheric Administration (NOAA) and presents US State temperature extremes and drought information (7). Visitors can see all-time temperature maximums and minimums by state, monthly temperatures by state, and more. The last site is an all-inclusive temperature site called Temperature World (8). Everything from news, science, organizations, general interest, games, and more -- all related to temperature -- can be found here.

Brieske, Joel A.

361

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

362

Non-linear response of springtime vegetation green-up to temperature over northern temperate and boreal forests  

NASA Astrophysics Data System (ADS)

An annual cycle of vegetation is responsive to climate and environmental changes. Changes in the cycle dominantly affect terrestrial ecosystem as well as surrounding atmosphere. However, our understanding of the cycle is mostly confined to the mechanisms and attributions of specific events in the growth cycle (e.g., spring emergence and fall senescence). Here we focused on large-scale variations in the rate of vegetation green-up (Rgreen) that indicates a rate of transition between the wintertime dormancy and the summertime maturity. Using satellite-retrieved normalized difference vegetation index and station-merged temperature observations, it was examined that responses of the Rgreen to accompanied variations in 15-day mean temperature, hereafter the growth temperature, over northern temperate and boreal forests for the period 1982-2008. Averaged over the analysis period, the Rgreen increases with latitude, indicating that high-latitude vegetation more quickly growth from their dormancy to mature phase compared to mid-latitude vegetation. On inter-annual timescale, the Rgreen and the growth temperature show a significant positive relation over the study region (r = 0.59 in Eurasia, p < 0.05). It means that an increase of the growth temperature accelerates the Rgreen over most of temperate and boreal forest in Northern Hemisphere. With the prevailing positive relationship, the responses of Rgreen show an asymmetric pattern that a strong acceleration in the condition of positive growth temperature anomalies but a weak deceleration with the opposite condition. In the situation of climate change, these results imply that a possibility of drastic alteration in temperate and boreal forest growth that closely associated with carbon allocation, hydrological budget, and other vegetation interactions.

Park, H.; Jeong, S.; Ho, C.

2013-12-01

363

Child Trends  

NSDL National Science Digital Library

Child Trends is a non-profit, non-partisan research center, and is the "nation's only independent research and policy center focused exclusively on improving outcomes for children." Child Trends has twelve areas of research, listed across the top of any page. Some of the topics include "Child Poverty," "Fatherhood & Parenting," "Youth Development," and "Health." In each section, the research focus on that topic is explained in a brief introduction, followed by resources that include research briefs, executive summaries and full reports, fact sheets, and a publications archive of materials over three years old. A feature that visitors shouldn't miss is "What Works/LINKS," which can be accessed via the left side menu. The data in this section is about "programs that work -or don't- to enhance children's development". There are effectiveness charts, "Lifecourse Interventions that Work," and a continually updated database on programs that work (or don't). Visitors who are "Program Providers" in policy, education, or the media will find the "Information for..." heading on the left side of the homepage useful for fulfilling their specific needs.

364

Non-linear dynamical analyses of transient surface temperature fluctuations during subcooled pool boiling on a horizontal disk  

E-print Network

2009 Keywords: Boiling Thin film thermocouples Correlation dimension Critical heat flux Leidenfrost developed nucleate boil- ing (FDNB) $7­9 near critical heat flux (CHF) condition, and from $6.6 to 7 experiments on a 62.23 mm diameter silicon wafer using PF-5060 as the test liquid. Surface temperature data

Banerjee, Debjyoti

365

Indices for daily temperature and precipitation extremes in Europe analyzed for the period 1901-2000  

Microsoft Academic Search

We analyze century-long daily temperature and precipitation records for stations in Europe west of 60°E. A set of climatic indices derived from the daily series, mainly focusing on extremes, is defined. Linear trends in these indices are assessed over the period 1901-2000. Average trends, for 75 stations mostly representing Europe west of 20°E, show a warming for all temperature indices.

Anders Moberg; Philip D. Jones; David Lister; Alexander Walther; Manola Brunet; Jucundus Jacobeit; Lisa V. Alexander; Paul M. Della-Marta; Jürg Luterbacher; Pascal Yiou; Deliang Chen; Albert M. G. Klein Tank; Oscar Saladié; Javier Sigró; Enric Aguilar; Hans Alexandersson; Carlos Almarza; Ingeborg Auer; Mariano Barriendos; Michael Begert; Hans Bergström; Reinhard Böhm; C. J. Butler; John Caesar; Achim Drebs; Dmitra Founda; Friedrich-Wilhelm Gerstengarbe; Giusi Micela; Maurizio Maugeri; Hermann Österle; Kreso Pandzic; Michael Petrakis; Lidija Srnec; Radim Tolasz; Heikki Tuomenvirta; Peter C. Werner; Hans Linderholm; Andreas Philipp; Heinz Wanner; Elena Xoplaki

2006-01-01

366

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

367

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

368

Temperature  

NSDL National Science Digital Library

This article discusses the relationship between temperature and heat and kinetic energy and it shows how to convert from degrees Fahrenheit to Centigrade. It also includes links to other resources, data, maps, and classroom activities.

2008-04-08

369

Quantifying the respective contribution of wind stress and diabatic forcing to decadal temperature changes and regional sea level trends over 1993-2010 based on ECCO solutions  

NASA Astrophysics Data System (ADS)

Since 1993 and based on satellite altimetry data, sea level trends display a large regional variability. Some regions experience a sea level rise (e.g., the west tropical Pacific Ocean, the subpolar north Atlantic Ocean...) whereas other regions experience a drop (e.g., the east tropical Pacific Ocean, golf of Alaska...). Those sea level trends appear to be steric in nature. Moreover, steric changes appear to be mainly thermosteric, although halosteric effects can reduce or enhance thermosteric changes in some specific regions (Stammer et al., 2013). Understanding and quantifying the processes involved in regional sea level changes are important tasks to better constrain and ascertain the physical processes involved in regional sea level changes and then, to improve predictions to anticipate potential impacts. In this study, we analyze the ocean heat content change and its origin by analyzing Estimating the Circulation and Climate of the Ocean estimates (ECCO, Wunsch et al., 2009). We run numerical experiments to estimate and quantify the respective contribution of each atmospheric forcing (e.g., wind stress and diabatic forcing) to heat content change and regional sea level trends.

Llovel, W.; Fukumori, I.; Wang, O.

2013-12-01

370

Fertilizer trends  

SciTech Connect

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 decisions. A 27-year summary of the US fertilizer market is presented in graphic and tabular form. Production, use, and trade data are included for each plant nutrient and sulfur. Canadian statistics have been included because of the important role of the Canadian fertilizer industry in the US fertilizer market. World production and consumption of nitrogen, phosphate, and potash are included because of the strong influence of world markets on the domestic market. Planted acreage and plant nutrient application rates for the major crops have been included to illustrate their effect on fertilizer use. Retail prices of the leading US fertilizer materials also are given.

Donaldson, R.

1992-12-31

371

Fertilizer trends  

SciTech Connect

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 decisions. A 27-year summary of the US fertilizer market is presented in graphic and tabular form. Production, use, and trade data are included for each plant nutrient and sulfur. Canadian statistics have been included because of the important role of the Canadian fertilizer industry in the US fertilizer market. World production and consumption of nitrogen, phosphate, and potash are included because of the strong influence of world markets on the domestic market. Planted acreage and plant nutrient application rates for the major crops have been included to illustrate their effect on fertilizer use. Retail prices of the leading US fertilizer materials also are given.

Donaldson, R.

1992-01-01

372

Non-linear effects in a spherical convection experiments with temperature dependent fluid properties: Microgravity experiment and numerical simulations  

NASA Astrophysics Data System (ADS)

Thermal convection is one important driving mechanism of flow in the earth mantle. Setting up a self-gravitating buoyancy in a spherical shell geometry is the limiting factor for laboratory experiments to analyze velocity flow structures and heat transport. The geophysical flow model 'GeoFlow II', which is located at the Columbus module on the ISS, realizes such a central gravity. Under microgravity conditions a central dielectrophoretic force field is applied to a fluid filled spherical annulus. In contrast to the first mission 'GeoFlow I' the electro-hydrodynamical volume expansion coefficient of the working fluid has a strong dependence on the temperature and leads to pattern, which are related to a strong temperature dependent viscosity of the fluid. Even though the oil's viscosity itself is temperature-dependent, too, the maximum of viscosity contrast is only up to 1.5. The optical measurement of the fluid flow is based on the Wollaston shearing interferometry, since the on orbit setup avoids the use of measurement particles. This technique leads to fringe patterns. Simulations with RESPECT and GAIAA tend to verify the experimentally observed patterns by different numerical models.

Zaussinger, F.; Futterer, B.; Egbers, C.

2012-12-01

373

Observation of Lorentzian lineshapes in the room temperature optical spectra of strongly coupled Jaggregate/metal hybrid nanostructures by linear two-dimensional optical spectroscopy  

NASA Astrophysics Data System (ADS)

We analyze the linear optical reflectivity spectra of a prototypical, strongly coupled metal/molecular hybrid nanostructure by means of a new experimental approach, linear two-dimensional optical spectroscopy. White-light, broadband spectral interferometry is used to measure amplitude and spectral phase of the sample reflectivity or transmission with high precision and to reconstruct the time structure of the electric field emitted by the sample upon impulsive excitation. A numerical analysis of this time-domain signal provides a two-dimensional representation of the coherent optical response of the sample as a function of excitation and detection frequency. The approach is used to study a nanostructure formed by depositing a thin J-aggregated dye layer on a gold grating. In this structure, strong coupling between excitons and surface plasmon polaritons results in the formation of hybrid polariton modes. In the strong coupling regime, Lorentzian lineshape profiles of different polariton modes are observed at room temperature. This is taken as an indication that the investigated strongly coupled polariton excitations are predominantly homogeneously broadened at room temperature. This new approach presents a versatile, simple and highly precise addition to nonlinear optical spectroscopic techniques for the analysis of line broadening phenomena.

Wang, Wei; Vasa, Parinda; Sommer, Ephraim; De Sio, Antonietta; Gross, Petra; Vogelgesang, Ralf; Lienau, Christoph

2014-11-01

374

Global Temperatures  

NSDL National Science Digital Library

In this activity, students create graphs of real temperature data to analyze climate trends by analyzing the global temperature record from 1867 to the present. Long-term trends and shorter-term fluctuations are both evaluated. The data is examined for evidence of the impact of natural and anthropogenic climate forcing mechanisms on the global surface temperature variability. Students are prompted to determine the difficulties scientists face in using this data to make climate predictions.

Robert MacKay

375

PEG-stabilized core-shell nanoparticles: impact of linear versus dendritic polymer shell architecture on colloidal properties and the reversibility of temperature-induced aggregation.  

PubMed

Superparamagnetic iron oxide nanoparticles (SPIONs) have been widely used experimentally and also clinically tested in diverse areas of biology and medicine. Applications include magnetic resonance imaging, cell sorting, drug delivery, and hyperthermia. Physicochemical surface properties are particularly relevant in the context of achieving high colloidal nanoparticle (NP) stability and preventing agglomeration (particularly challenging in biological fluids), increasing blood circulation time, and possibly targeting specific cells or tissues through the presentation of bioligands. Traditionally, NP surfaces are sterically stabilized with hydrophilic polymeric matrices, such as dextran or linear poly(ethylene glycol) brushes. While dendrimers have found applications as drug carriers, dispersants with dendritic ("dendrons") or hyperbranched structures have been comparatively neglected despite their unique properties, such as a precisely defined molecular structure and the ability to present biofunctionalities at high density at the NP periphery. This work covers the synthesis of SPIONs and their stabilization based on poly(ethylene glycol) (PEG) and oligo(ethylene glycol) (OEG) chemistry and compares the physicochemical properties of NPs stabilized with linear and dendritic macromolecules of comparable molecular weight. The results highlight the impact of the polymeric interface architecture on solubility, colloidal stability, hydrodynamic radius, and thermoresponsive behavior. Dendron-stabilized NPs were found to provide excellent colloidal stability, despite a smaller hydrodynamic radius and lower degree of soft shell hydration compared to linear PEG analogues. Moreover, for the same grafting density and molecular weight of the stabilizers, OEG dendron-stabilized NPs show a reversible temperature-induced aggregation behavior, in contrast to the essentially irreversible aggregation and sedimentation observed for the linear PEG analogues. This new class of dendritically stabilized NPs is believed to have a potential for future biomedical and other applications, in which stability, resistance to (or reversible) aggregation, ultrasmall size (for crossing biological barriers or inclusion in responsive artificial membranes), and/or high corona density of (bio)active ligands are key. PMID:23214719

Gillich, Torben; Acikgöz, Canet; Isa, Lucio; Schlüter, A Dieter; Spencer, Nicholas D; Textor, Marcus

2013-01-22

376

Temperature and geographic attribution of change in the Taraxacum mongolicum growing season from 1990 to 2009 in eastern China's temperate zone  

NASA Astrophysics Data System (ADS)

Using leaf unfolding and leaf coloration data of a widely distributed herbaceous species, Taraxacum mongolicum, we detected linear trend and temperature response of the growing season at 52 stations from 1990 to 2009. Across the research region, the mean growing season beginning date marginal significantly advanced at a rate of -2.1 days per decade, while the mean growing season end date was significantly delayed at a rate of 3.1 days per decade. The mean growing season length was significantly prolonged at a rate of 5.1 days per decade. Over the 52 stations, linear trends of the beginning date correlate negatively with linear trends of spring temperature, whereas linear trends of the end date and length correlate positively with linear trends of autumn temperature and annual mean temperature. Moreover, the growing season linear trends are also closely related to the growing season responses to temperature and geographic coordinates plus elevation. Regarding growing season responses to temperature, a 1 °C increase in regional mean spring temperature results in an advancement of 2.1 days in regional mean growing season beginning date, and a 1 °C increase in regional mean autumn temperature causes a delay of 2.3 days in regional mean growing season end date. A 1 °C increase in regional annual mean temperature induces an extension of 8.7 days in regional mean growing season length. Over the 52 stations, response of the beginning date to spring temperature depends mainly on local annual mean temperature and geographic coordinates plus elevation. Namely, a 1 °C increase in spring temperature induces a larger advancement of the beginning date at warmer locations with lower latitudes and further west longitudes than at colder locations with higher latitudes and further east longitudes, while a 1 °C increase in spring temperature causes a larger advancement of the beginning date at higher than at lower elevations.

Chen, Xiaoqiu; Tian, Youhua; Xu, Lin

2015-01-01

377

Research and development program for non-linear structural modeling with advanced time-temperature dependent constitutive relationships  

NASA Technical Reports Server (NTRS)

Results of a 20-month research and development program for nonlinear structural modeling with advanced time-temperature constitutive relationships are reported. The program included: (1) the evaluation of a number of viscoplastic constitutive models in the published literature; (2) incorporation of three of the most appropriate constitutive models into the MARC nonlinear finite element program; (3) calibration of the three constitutive models against experimental data using Hastelloy-X material; and (4) application of the most appropriate constitutive model to a three dimensional finite element analysis of a cylindrical combustor liner louver test specimen to establish the capability of the viscoplastic model to predict component structural response.

Walker, K. P.

1981-01-01

378

Linear variable differential transformer (LVDT)-based elongation measurements in Advanced Test Reactor high temperature irradiation testing  

SciTech Connect

New materials are being considered for fuel, cladding, and structures in next generation and existing nuclear reactors. These materials can undergo significant dimensional and physical changes during high temperature irradiations. Currently, such changes are determined by repeatedly irradiating a specimen for a specified period of time in the Advanced Test Reactor (ATR) and then removing it from the reactor for evaluation. The labor and time to remove, examine, and return irradiated samples for each measurement makes this approach very expensive. In addition, such techniques provide limited data and may disturb the phenomena of interest. To resolve these issues, an instrumented creep testing capability is being developed for specimens irradiated in pressurized water reactor (PWR) coolant conditions in the ATR at the Idaho National Laboratory (INL). This paper reports the status of INL efforts to develop this testing capability. In addition to providing an overview of in-pile creep test capabilities available at other test reactors, this paper focuses on efforts to design and evaluate a prototype test rig in an autoclave at INL's High Temperature Test Laboratory (HTTL).

D. L. Knudson; J. L. Rempe

2012-02-01

379

Linear variable differential transformer (LVDT)-based elongation measurements in Advanced Test Reactor high temperature irradiation testing  

SciTech Connect

New materials are being considered for fuel, cladding and structures in next generation and existing nuclear reactors. These materials can undergo significant dimensional and physical changes during high temperature irradiations. Currently, such changes are determined by repeatedly irradiating a specimen for a specified period of time in the Advanced Test Reactor (ATR) and then removing it from the reactor for evaluation. The labor and time to remove, examine and return irradiated samples for each measurement make this approach very expensive. In addition, such techniques provide limited data and may disturb the phenomena of interest. To resolve these issues, an instrumented creep testing capability is being developed for specimens irradiated under pressurized water reactor coolant conditions in the ATR at the Idaho National Laboratory (INL). This paper reports the status of INL efforts to develop this testing capability. In addition to providing an overview of in-pile creep test capabilities available at other test reactors, this paper focuses on efforts to design and evaluate a prototype test rig in an autoclave at INL’s High Temperature Test Laboratory.

D. L. Knudson; J. L. Rempe

2012-02-01

380

Linear variable differential transformer (LVDT)-based elongation measurements in Advanced Test Reactor high temperature irradiation testing  

NASA Astrophysics Data System (ADS)

New materials are being considered for fuel, cladding and structures in next generation and existing nuclear reactors. These materials can undergo significant dimensional and physical changes during high temperature irradiations. Currently, such changes are determined by repeatedly irradiating a specimen for a specified period of time in the Advanced Test Reactor (ATR) and then removing it from the reactor for evaluation. The labor and time to remove, examine and return irradiated samples for each measurement make this approach very expensive. In addition, such techniques provide limited data and may disturb the phenomena of interest. To resolve these issues, an instrumented creep testing capability is being developed for specimens irradiated under pressurized water reactor coolant conditions in the ATR at the Idaho National Laboratory (INL). This paper reports the status of INL efforts to develop this testing capability. In addition to providing an overview of in-pile creep test capabilities available at other test reactors, this paper focuses on efforts to design and evaluate a prototype test rig in an autoclave at INL's High Temperature Test Laboratory.

Knudson, D. L.; Rempe, J. L.

2012-02-01

381

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

382

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

383

Temperature  

NASA Technical Reports Server (NTRS)

The problems in human comfort in heat stress are emphasized, with less emphasis placed upon cold exposure problems. Physiological parameters related to human thermal interactions are discussed, as well as data concerning thermal protective clothing. The energy balance equation, heat transfer equation, thermal comfort, heat stress, and cold stress are also considered. A two node model of human temperature regulation in FORTRAN is appended.

Berenson, P. J.; Robertson, W. G.

1973-01-01

384

Temperature and non-linear response of cantilever-type mechanical oscillators used in atomic force microscopes with interferometric detection  

NASA Astrophysics Data System (ADS)

The sensitivity of atomic force microscopes is fundamentally limited by the cantilever temperature, which can be, in principle, determined by measuring its thermal spectrum and applying the equipartition theorem. However, the mechanical response can be affected by the light field inside the cavi