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1

Propagation of linear surface air temperature trends into the terrestrial subsurface  

NASA Astrophysics Data System (ADS)

Previous studies have tested the long-term coupling between air and terrestrial subsurface temperatures working under the assumption that linear trends in surface air temperature should be equal to those measured at depth within the subsurface. A one-dimensional model of heat conduction is used to show that surface trends are attenuated as a function of depth within conductive media on time scales of decades to centuries, therefore invalidating the above assumption given practical observational constraints. The model is forced with synthetic linear 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, propagating surface trends are progressively damped with depth in both noise-free and noise-added scenarios. Over shorter intervals, the relationship between surface and subsurface trends is more variable and is strongly impacted by annual variability (i.e., noise). Using output from the FOR1 millennial simulation of the GKSS ECHO-G General Circulation Model as a more realistic surface forcing function for the conductive model, it is again demonstrated that surface trends are damped as a function of depth within the subsurface. Observational air and subsurface temperature data collected over 100 years in Armagh, Ireland, and 29 years in Fargo, North Dakota, are also analyzed and shown to have subsurface temperature trends that are not equal to the surface trend. While these conductive effects are correctly accounted for in inversions of borehole temperature profiles in paleoclimatic studies, they have not been considered in studies seeking to evaluate the long-term coupling between air and subsurface temperatures by comparing trends in their measured time series. The presented results suggest that these effects must be considered and that a demonstrated trend equivalency in air and subsurface temperatures is inconclusive regarding their long-term tracking.

Lesperance, Marielle; Smerdon, Jason E.; Beltrami, Hugo

2010-11-01

2

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

3

Comparison between linear and nonlinear trends in NOAA-15 AMSU-A brightness temperatures during 1998-2010  

NASA Astrophysics Data System (ADS)

Brightness temperature observations from Microwave Sounding Unit and Advanced Microwave Sounding Unit-A (AMSU-A) on board National Oceanic and Atmospheric Administration (NOAA) satellites have been widely utilized for estimating the global climate trend in the troposphere and stratosphere. A common approach for deriving the trend is linear regression, which implicitly assumes the trend being a straight line over the whole length of a time series and is often highly sensitive to the data record length. This study explores a new adaptive and temporally local data analysis method—Ensemble Empirical Mode Decomposition (EEMD)—for estimating the global trends. In EEMD, a non-stationary time series is decomposed adaptively and locally into a sequence of amplitude-frequency modulated oscillatory components and a time-varying trend. The AMSU-A data from the NOAA-15 satellite over the time period from October 26, 1998 to August 7, 2010 are employed for this study. Using data over Amazon rainforest areas, it is shown that channel 3 is least sensitive to the orbital drift among four AMSU-A surface sensitive channels. The decadal trends of AMSU-A channel 3 and other eight channels in the troposphere and stratosphere are deduced and compared using both methods. It is shown that the decadal climate trends of most AMSU-A channels are nonlinear except for channels 3-4 in Northern Hemisphere only and channels 12-13. Although the decadal trend variation of the global average brightness temperature is no more than 0.2 K, the regional decadal trend variation could be more (less) than 3 K (-3 K) in high latitudes and over high terrains.

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

2012-10-01

4

Trends in stratospheric temperature  

NASA Technical Reports Server (NTRS)

Stratospheric temperatures for long-term and recent trends and the determination of whether observed changes in upper stratospheric temperatures are consistent with observed ozone changes are discussed. The long-term temperature trends were determined up to 30mb from radiosonde analysis (since 1970) and rocketsondes (since 1969 and 1973) up to the lower mesosphere, principally in the Northern Hemisphere. The more recent trends (since 1979) incorporate satellite observations. The mechanisms that can produce recent temperature trends in the stratosphere are discussed. The following general effects are discussed: changes in ozone, changes in other radiatively active trace gases, changes in aerosols, changes in solar flux, and dynamical changes. Computations were made to estimate the temperature changes associated with the upper stratospheric ozone changes reported by the Solar Backscatter Ultraviolet (SBUV) instrument aboard Nimbus-7 and the Stratospheric Aerosol and Gas Experiment (SAGE) instruments.

Schoeberl, M. R.; Newman, P. A.; Rosenfield, J. E.; Angell, J.; Barnett, J.; Boville, B. A.; Chandra, S.; Fels, S.; Fleming, E.; Gelman, M.

1989-01-01

5

Temperature trends in the mesosphere  

NASA Astrophysics Data System (ADS)

We have performed trend studies in the mesosphere in the period 1961-2009 with LIMA (Leibniz-Institute Middle Atmosphere model) which is based on ECMWF below approximately 40 km and adapts temporal variations of CO2 and O3 according to observations. There is general agreement between LIMA and observations. Temperatures in the mesosphere/lower thermosphere vary non-uniformly with time, mainly due to the influence of ozone. We have therefore separated the influence of CO2(t) and O3(t) when determining trends. It is important to distinguish between trends on pressure altitudes, zp, and geometric altitudes, zgeo, where the latter includes the effect of shrinking due to cooling at lower heights. Maximum total temperature trends reach approximately -1,3 K/dec at zp ~60 km and -1.8 K/dec at zgeo ~70 km, respectively. Carbon dioxide is the main driver of these trends in the mesosphere, whereas ozone contributes approximately one third, both on geometric and pressure heights. Depending on the time period chosen, the ozone effect on trends can be significantly smaller or larger. Temperature trends on geometric and pressure altitudes can differ by as much as -0.9 K/dec in the mesosphere. The altitudes of pressure levels in the mesosphere decrease up to several hundred meters. The shift maximizes at mesopause levels where it accumulates to more than 1 km. Most of the shrinking occurs in the mesosphere and a smaller fraction (~20%) in the stratosphere. For the first time, we have performed long term runs with LIMA applying the 20th Century Reanalysis from NCEP/NCAR dating back to 1871. Again, trends are non-uniform with time. Since the late 19th century temperatures in the mesosphere have dropped by approximately 5-7 K on pressure altitudes, and up to 10-12 K on geometric altitudes. This is much more then typical trends in the troposphere and stratosphere. It is therefore justified to summarize that the mesosphere (at least in summer and at middle latitudes) reacts substantially more sensitive to climate change compared to lower altitudes.

Lübken, Franz-Josef; Berger, Uwe

2013-04-01

6

Mesospheric trends of temperatures and ice clouds  

NASA Astrophysics Data System (ADS)

The Leibniz-Institute Middle Atmosphere Model LIMA is used to study mesospheric trends in summer during the last decades. In order to account for realistic atmospheric conditions LIMA adapts several observational data sets, amongst others the tropospheric and stratospheric temperatures and winds from ECMWF, daily Lyman alpha fluxes, carbon dioxide concentrations, and total ozone. With a coupled microphysical model (LIMA-ICE) the effects on noctilucent clouds (NLC) are investigated since they are considered to be tracers for changes in the mesosphere. We present several comparisons of simulated trends with observations regarding the background atmosphere (temperatures, ionospheric reflection heights) and mesospheric ice clouds. In general there is good agreement between trends from LIMA and observations. Cooling in the mesosphere is on the order of 2-4 K/decade. The magnitude of the mesospheric temperature trend varies during the last five decades. In particular, the period from 1979-1997 shows large mesospheric cooling of 3-5 K/decade. This large cooling is primarily caused by long term changes of ozone in the upper stratosphere in combination with an increase of carbon dioxide. From our model results we identify sources of trends and their effects on ice layers. We critically discuss the role of mesospheric ice clouds as indicators for global change.Summerly averaged temperature anomalies at 70 km altitude derived from LIMA at 50°N, 7°E. Linear trends (red lines) are determined for run 1 from multiple regression which considers solar activity. Ozone anomalies (black) are taken from SBUV at 0.70~hPa and from WMO for the period 1961-1978 (from Berger and Lübken, Geophys. Res. Lett., 2011).

Luebken, F.; Berger, U.

2012-12-01

7

Southwest Pacific temperatures: trends in maximum and minimum temperatures  

Microsoft Academic Search

Diurnal temperature trends are described for newly homogenised climate data sets for a large area of the South Pacific. The diurnal trends differ from those documented for Northern Hemisphere land areas, where decreases are observed in the diurnal temperature range as a result of increases principally in minimum temperature. The Southwest Pacific divides into four regions that share coherent diurnal

M. J. Salinger

1995-01-01

8

Detection of Regional Surface Temperature Trends  

Microsoft Academic Search

Trends in surface temperature over the last 100, 50, and 30 yr at individual grid boxes in a 5° latitude longitude grid are compared with model estimates of the natural internal variability of these trends and with the model response to increasing greenhouse gases and sulfate aerosols. Three different climate models are used to provide estimates of the internal variability

David J. Karoly; Qigang Wu

2005-01-01

9

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

SciTech Connect

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

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

1993-10-01

10

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

11

Middle Atmosphere Temperature Trends from Small Rocketsondes  

NASA Technical Reports Server (NTRS)

Stratospheric temperature trends derived from United States meteorological rocketsonde measurements obtained between the late 1960's and mid 1990's are examined at the 50-, 40-, and 25-km altitude levels. Although the trends are different at each of the launch locations there is an unequivocal downward slope of about -0.1 K to -0.3K per year at many of the launch sites. Distances between launch sites and, in some cases unequal data-record lengths, inhibit determination of trend inter-relationship among the various sites. Although the data only provide a 'snapshot' of atmospheric behavior for the specific location, a particular advantage resulting from using these particular rocketsonde observations is their consistency over time. Thus, using the same rocketsonde type over the data period, i.e., Datasonde insures a significant reduction of instrument induced anomalies in the temperature profiles. Trends at the 25-km altitude level, approximately 30 hPa, are compared with trends from radiosonde observations. Both rocketsonde and radiosonde measurements were obtained at approximately the same local times and within less than 100 km of each other. Rocketsonde temperatures from the Former Soviet Union are also used and often complement trends from US data.

Schmidlin, F. J.

2002-01-01

12

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

13

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.

14

What may we conclude about global tropospheric temperature trends?  

Microsoft Academic Search

Three realizations of the atmospheric temperature representing the layer from the surface to about 18 km generated from microwave emissions were published in 2003. Their 1979–2002 linear trends were stated as +0.24 ± 0.02, +0.12 ± 0.02 and +0.03 ± 0.05°C decade?1. Because the upper portion of this layer includes the stratosphere, the opportunity to utilize radiosonde measurements as an

John R. Christy; William B. Norris

2004-01-01

15

Southwest Pacific temperatures: Diurnal and seasonal trends  

SciTech Connect

The authors present information on temperature trends for New Zealand, and by inference for the Southwest Pacific, since the island has its climate dramatically influenced by the surrounding ocean. A large number of climate stations from New Zealand and outlying islands have long term historical data records, for a region whose environment is unaffected by dense population or industry. Observed temperature changes are broadly in agreement with globally averaged temperature changes. Diurnal trends are different than for the Northern Hemisphere, in that for the last 50 years most stations, particularly the island stations, show daily and nightly warming trends. In the Southwest Pacific the most likely explanation in terms of suggested warming methods is an increase in cloud cover and in greenhouse gas loads. Atmospheric sulfates are not prevalent in this area. The close relationship of the island to the ocean means that most of the sites provide a good picture of the temperature behavior of the surrounding ocean. This suggest surface ocean waters must be increasing in temperature.

Salinger, M.J.; Hay, J.; McGann, R.; Fitzharris, B.

1993-05-21

16

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

17

Tests for Linear Trend in the Smallest Eigenvalues of the Correlation Matrix.  

ERIC Educational Resources Information Center

A test for linear trend among a set of eigenvalues of a correlation matrix is described. It is a generalization of G. Anderson's (1965) test for the equality of eigenvalues and extends the present authors' previous work on linear trends in eigenvalues of a covariance matrix. The linear trend hypothesis is discussed. (SLD)

Bentler, Peter M.; Yuan, Ke-Hai

1998-01-01

18

Global trends of measured surface air temperature  

NASA Astrophysics Data System (ADS)

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 which is designed to provide accurate long-term variations. Error estimates are based in part on studies of how accurately the actual station distributions are able to reproduce temperature change in a global data set produced by a three-dimensional general circulation model with realistic variability. We find that meaningful global temperature change can be obtained for the past century, despite the fact that the meteorological stations are confined mainly to continental and island locations. The results indicate a global warming of about 0.5°-0.7°C in the past century, with warming of similar magnitude in both hemispheres; the northern hemisphere result is similar to that found by several other investigators. A strong warming trend between 1965 and 1980 raised the global mean temperature in 1980 and 1981 to the highest level in the period of instrumental records. The warm period in recent years differs qualitatively from the earlier warm period centered about 1940; the earlier warming was focused at high northern latitudes, while the recent warming is more global. We present selected graphs and maps of the temperature change in each of the eight latitude zones. A computer tape of the derived regional and global temperature changes is available from the authors.

Hansen, James; Lebedeff, Sergej

1987-11-01

19

The Linear ?-MODEL and Finite Temperature Effects  

NASA Astrophysics Data System (ADS)

We discuss the temperature effects on the masses and couplings constants in the linear ?-model including the effective pion decay constant f?(T). We analyze in detail the region where our discussion is valid. The temperature effects on masses include an explicit discussion concerning the role of the thermal tadpoles as a mass contribution due to the vacuum.

Contreras, C.; Loewe, M.

20

Observed soil temperature trends associated with climate change in Canada  

Microsoft Academic Search

Trends in soil temperature are important, but rarely reported, indicators of climate change. On the basis of the soil temperature data from 30 climate stations across Canada during 1958–2008, trends in soil temperatures at 5, 10, 20, 50, 100, and 150 cm depths were analyzed, together with atmospheric variables, such as air temperature, precipitation, and depth of snow on the

Budong Qian; Edward G. Gregorich; Sam Gameda; David W. Hopkins; Xiaolan L. Wang

2011-01-01

21

Simulation of mesospheric temperature trends at mid latitudes in summer  

NASA Astrophysics Data System (ADS)

The LIMA Leibniz-Institute Middle Atmosphere Model is used to study mesospheric temperature trends during the last 5 decades from 1961 until 2010. In order to account for realistic atmospheric conditions LIMA adapts several observational data sets, such as tropospheric and stratospheric temperatures and winds from ECMWF at heights 0-35 km, daily Lyman-alpha fluxes, and monthly carbon dioxide concentrations since 1961, and the monthly ozone profiles up to 0.6 hPa provided from SBUV/TOMS satellite instruments since 1979. This paper presents a comparison of simulated temperature trends with groundbased observations of temperature (lidar) and phase height trends (radiowave technique) at mid-latitudes (45-50N) and temperature trends derived from satellite data (SSU). Generally good agreement is found between model trends and trends derived from observations without any significant differences. As a major result the greenhouse warming in the lower troposphere reverses to a cooling trend in the mesosphere where the magnitude of the trend of 2-4 K/decade is about a factor of 10 larger than compared to trends in global mean surface temperature which are about 0.2 K/decade. The size of mesospheric temperature trend is not constant during the last 5 decades. Especially, the period from 1979 - 1997 shows a large mesospheric cooling trend of 4-5 K/decade which is mainly affected by an upper stratospheric ozone decrease over the same period.

Berger, U.; Luebken, F.

2011-12-01

22

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

23

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

24

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

25

Trends in precipitation and temperature in Florida, USA  

NASA Astrophysics Data System (ADS)

SummaryAnnual, seasonal, and monthly trends in precipitation, mean temperature, maximum temperature, minimum temperature, and temperature range were evaluated using stations from the United States Historical Climatology Network (USHCN) for the time periods 1895-2009 and 1970-2009 for the state of Florida. The significance and magnitude of station trends were determined using the non-parametric Mann-Kendall test and Sen's slope, respectively. The collective, field significance of trends were evaluated using a Monte Carlo permutation procedure. Field significant trends in seasonal precipitation were found in only the June-August and March-May seasons for the 1895-2009 and 1970-2009 time periods, respectively. Significant decreasing trends in monthly precipitation were found in the months of October and May for the 1895-2009 and 1970-2009 time periods, respectively. Field significant trends were found for all temperature variables for both time periods, with the largest number of stations with significant trends occurring in the summer and autumn months. Trends in mean, maximum, and minimum temperature were generally positive with a higher proportion of positive trends in the 1970-2009 period. The spatial coherence of trends in temperature range was generally less compared to other temperature variables, with a larger proportion of stations showing negative trends in the summer and positive trends at other times of the year and more negative trends found in the 1970-2009 period. Significant differences in temperature trends based on the surrounding land use were found for minimum temperature and temperature range in the 1970-2009 period indicating that data homogenization of the USHCN temperature data did not fully remove this influence. The evaluation of trends based on station exposure ratings shows significant differences in temperature variables in both the 1895-2009 and 1970-2009 time periods. Systematic changes in trends can be seen in the 1980s, the period of widespread conversion from liquid-in-glass to electronic measurement, indicating that some of the differences found may be due to uncorrected inhomogeneities. Since notable differences were found between differently rated stations pre-1940, a time which the present-day rating should have little to no influence, attribution of differences based on station rating should be done with caution.

Martinez, Christopher J.; Maleski, Jerome J.; Miller, Martin F.

2012-07-01

26

Mesospheric temperature trends at mid-latitudes in summer  

NASA Astrophysics Data System (ADS)

The Leibniz-Institute Middle Atmosphere Model LIMA is used to study mesospheric temperature trends in summer during the last 5 decades (1961-2009). In order to account for realistic atmospheric conditions LIMA adapts several observational data sets, namely a) tropospheric and stratospheric temperatures and winds from ECMWF at heights 0-35 km, b) daily Lyman-? fluxes, c) monthly carbon dioxide concentrations since 1961, and d) annual total ozone from ground-based data for 1964-1978 and monthly ozone profiles up to 0.60 hPa from satellites since 1979. This paper presents a comparison of simulated temperature trends with a) ground-based observations of lidar temperatures at 44°N, b) phase height measurements at mid-latitudes (51°N), and c) temperature trends derived from satellite data. In general there is excellent agreement between trends from LIMA and observations. Cooling in the mesosphere is on the order of 2-4 K/decade. The magnitude of the mesospheric temperature trend varies during the last five decades. In particular, the period from 1979-1997 shows large mesospheric cooling of 3-5 K/decade. This large cooling is primarily caused by long-term changes of ozone in the upper stratosphere in combination with a CO2 increase. For the first time, modeling of mesospheric temperature trends confirm the extraordinarily large trends from observations.

Berger, U.; Lübken, F.-J.

2011-11-01

27

Temperature and ice layer trends in the summer middle atmosphere  

NASA Astrophysics Data System (ADS)

We present results from our LIMA model (Leibniz Institute Middle Atmosphere Model) which nicely reproduces mean conditions of the summer mesopause region and also mean characteristics of ice layers known as noctilucent clouds. LIMA nudges to ECMWF data in the troposphere and lower stratosphere which influences the background conditions in the mesosphere. We study temperature trends in the mesosphere at middle and polar latitudes and compared with temperature trends from satellites, lidar, and phase height observations. For the first time large observed temperature trends in the summer mesosphere can be reproduced and explained by a model. As will be shown, stratospheric ozone has a major impact on temperature trends in the summer mesosphere. The temperature trend is not uniform in time: it is moderate from 1961 (the beginning of our record) until the beginning of the 1980s. Thereafter, temperatures decrease much stronger until the mid 1990s. Thereafter, temperatures are nearly constant or even increase with time. As will be shown, trends in ozone and carbon dioxide explain most of this behavior. Ice layers in the summer mesosphere are very sensitive to background conditions and are therefore considered to be appropriate tracers for long term variations in the middle atmosphere. We use LIMA background conditions to determine ice layer characteristics in the mesopause region. We compare our results with measurements, for example with albedos from the SBUV satellites, and show that we can nicely reproduce observed trends. It turns out that temperature trends are positive (negative) in the upper (lower) part of the ice layer regime. This complicates an interpretation of NLC long term variations in terms of temperature trends.

Lübken, F.-J.; Berger, U.

2012-04-01

28

Snow-albedo feedback and Swiss spring temperature trends  

NASA Astrophysics Data System (ADS)

We quantify the effect of the snow-albedo feedback on Swiss spring temperature trends using daily temperature and snow depth measurements from six station pairs for the period 1961-2011. We show that the daily mean 2-m temperature of a spring day without snow cover is on average 0.4 °C warmer than one with snow cover at the same location. This estimate is comparable with estimates from climate modelling studies. Caused by the decreases in snow pack, the snow-albedo feedback amplifies observed temperature trends in spring. The influence is small and confined to areas around the upward-moving snow line in spring and early summer. For the 1961-2011 period, the related temperature trend increases are in the order of 3-7 % of the total observed trend.

Scherrer, S. C.; Ceppi, P.; Croci-Maspoli, M.; Appenzeller, C.

2012-12-01

29

Simulation of recent global temperature trends  

Microsoft Academic Search

Observations show that global average tropospheric temperatures have been rising during the past century, with the most recent portion of record showing a sharp rise since the mid-1970s. This study shows that the most recent portion of the global temperature record (1970 to 1992) can be closely reproduced by atmospheric models forced only with observed ocean surface temperatures. In agreement

N. E. Graham

1995-01-01

30

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

31

Spuriously induced temperature trends in the Southeast United States  

NASA Astrophysics Data System (ADS)

This study uses correlation and multiple regression techniques to document differences in annual temperature trends between the National Climatic Data Center (NCDC) Climate Division Database (CDD) and the United States Historical Climate Network (USHCN) for the Southeast United States. Results indicate that an increase (decrease) in elevation and a northward (southward) shift in mean station location in the CDD correspond with decreases (increases) in temperature. Although the movement of station locations in the CDD showed only modest impacts on trends, the effects of the movements are statistically significant, and explain some of the variances in the temperature trends. Results therefore suggest that climate divisions with more rugged terrain and greater shifts in elevation are more susceptible to spuriously generated trends.

Allard, J.; Keim, B. D.

2007-01-01

32

Temperature trends in Malta (central Mediterranean) from 1951 to 2010  

NASA Astrophysics Data System (ADS)

There is as yet scanty published information on climate trends at a local scale within the central Mediterranean region. This is the most updated study that focuses on detailed understanding of air temperature shifts based on standard observations gathered from the Maltese islands. This analysis leads to a number of conclusions, most significant being (1) that the rate of change in the mean temperature is +1.1 °C between 1951 and 2010, (2) a warming trend of +1.2 and +1.1 °C exists in the maximum and minimum temperature, respectively, over the same period, (3) that the strongest anomalous warming has occurred during the last 30 years, particularly during the months of June, August and October, and (4) the local temperature trend is in the same category of air temperature trends detected in the nearby Island of Sicily (Catania, Italy), Perpignan (France) and Dar el-Beida (Algeria). Local data also show differences in the temperature trends, especially pronounced between the two 30-year periods of 1951-1980 and 1981-2010. This study provides an understanding of temperature shifts at recommended small spatio-temporal scales.

Galdies, C.

2012-08-01

33

Bird population trends are linearly affected by climate change along species thermal ranges  

PubMed Central

Beyond the effects of temperature increase on local population trends and on species distribution shifts, how populations of a given species are affected by climate change along a species range is still unclear. We tested whether and how species responses to climate change are related to the populations locations within the species thermal range. We compared the average 20 year growth rates of 62 terrestrial breeding birds in three European countries along the latitudinal gradient of the species ranges. After controlling for factors already reported to affect bird population trends (habitat specialization, migration distance and body mass), we found that populations breeding close to the species thermal maximum have lower growth rates than those in other parts of the thermal range, while those breeding close to the species thermal minimum have higher growth rates. These results were maintained even after having controlled for the effect of latitude per se. Therefore, the results cannot solely be explained by latitudinal clines linked to the geographical structure in local spring warming. Indeed, we found that populations are not just responding to changes in temperature at the hottest and coolest parts of the species range, but that they show a linear graded response across their European thermal range. We thus provide insights into how populations respond to climate changes. We suggest that projections of future species distributions, and also management options and conservation assessments, cannot be based on the assumption of a uniform response to climate change across a species range or at range edges only.

Jiguet, Frederic; Devictor, Vincent; Ottvall, Richard; Van Turnhout, Chris; Van der Jeugd, Henk; Lindstrom, Ake

2010-01-01

34

Bird population trends are linearly affected by climate change along species thermal ranges.  

PubMed

Beyond the effects of temperature increase on local population trends and on species distribution shifts, how populations of a given species are affected by climate change along a species range is still unclear. We tested whether and how species responses to climate change are related to the populations locations within the species thermal range. We compared the average 20 year growth rates of 62 terrestrial breeding birds in three European countries along the latitudinal gradient of the species ranges. After controlling for factors already reported to affect bird population trends (habitat specialization, migration distance and body mass), we found that populations breeding close to the species thermal maximum have lower growth rates than those in other parts of the thermal range, while those breeding close to the species thermal minimum have higher growth rates. These results were maintained even after having controlled for the effect of latitude per se. Therefore, the results cannot solely be explained by latitudinal clines linked to the geographical structure in local spring warming. Indeed, we found that populations are not just responding to changes in temperature at the hottest and coolest parts of the species range, but that they show a linear graded response across their European thermal range. We thus provide insights into how populations respond to climate changes. We suggest that projections of future species distributions, and also management options and conservation assessments, cannot be based on the assumption of a uniform response to climate change across a species range or at range edges only. PMID:20554552

Jiguet, Frédéric; Devictor, Vincent; Ottvall, Richard; Van Turnhout, Chris; Van der Jeugd, Henk; Lindström, Ake

2010-12-01

35

Trend analysis of river water temperatures in the Ebro River Basin (Spain)  

NASA Astrophysics Data System (ADS)

Water temperature is an important factor conditioning physical, biological and chemical processes in water courses. The huge changes along the last 50 years in land and water use (dam construction, urban development, nuclear power plants (NPP), riparian alteration, irrigation development, and return of agricultural lands to forests), along with climate change, call for the study of their influence on river water temperatures. This work analyzed the trends (1973-2010) in water temperature (Tw) along the Ebro River (14 water quality stations) in North-East Spain and its main tributaries (6 water quality stations), as a first step to assess its possible relationships with land use changes, climate change, and other factors. Water temperature trends (?Tw) were estimated by two different methods: (1) multiple regression incorporating year seasonality and linear trend; and (2) non-parametric Mann-Kendall seasonal trend estimator. A cluster analysis based on principal components (performed upon the variables Tw, ?Tw, annual Tw range, lag of the Tw annual cycle, coefficient of correlation between water and air temperature (Ta), and station altitude) allowed for grouping stations with similar behaviour in Tw (along the year, seasonality, and throughout the study period, trend). Trend analysis by the regression and Mann-Kendall methods produced similar results. They showed significant (P

Lorenzo-Gonzalez, Ma Angeles; Quilez, Dolores; Isidoro, Daniel

2014-05-01

36

Diurnal and seasonal cycles of trends of surface air temperature  

NASA Astrophysics Data System (ADS)

A new technique was recently developed to study seasonal cycles of climatic trends of expected values, variance, skewness, and other statistical moments of climatic variables. Here we apply that technique to analyze the diurnal and seasonal cycles of trends of surface air temperature and its variability using hourly observations from nine geographically distributed meteorological stations in the United States for the period 1951-1999. The analysis reveals a complex pattern of trends in temperature and its variance at different times of the seasonal and diurnal cycle, showing warming trends for all stations during most times of the year and times of day, but with diurnal asymmetry of warming only in the warm half of the year. We found no correspondence between the trends in temperature and the trends in temperature variability. This analysis may be used as a prototype for developing the next generation of climate services that will be able to supply customers with detailed information about the first few moments of the statistical distribution of any meteorological variable for every day and hour of the period of observation.

Vinnikov, Konstantin Y.; Robock, Alan; Basist, Alan

2002-11-01

37

Evaluation of trends in high temperature extremes in north-western Europe in regional climate models  

NASA Astrophysics Data System (ADS)

Projections of future changes in weather extremes on the regional and local scale depend on a realistic representation of trends in extremes in regional climate models (RCMs). We have tested this assumption for moderate high temperature extremes (the annual maximum of the daily maximum 2 m temperature, Tann.max). Linear trends in Tann.max from historical runs of 14 RCMs driven by atmospheric reanalysis data are compared with trends in gridded station data. The ensemble of RCMs significantly underestimates the observed trends over most of the north-western European land surface. Individual models do not fare much better, with even the best performing models underestimating observed trends over large areas. We argue that the inability of RCMs to reproduce observed trends is probably not due to errors in large-scale circulation. There is also no significant correlation between the RCM Tann.max trends and trends in radiation or Bowen ratio. We conclude that care should be taken when using RCM data for adaptation decisions.

Min, E.; Hazeleger, W.; van Oldenborgh, G. J.; Sterl, A.

2013-03-01

38

Temperature trends at high elevations: Patterns across the globe  

Microsoft Academic Search

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

N. C. Pepin; J. D. Lundquist

2008-01-01

39

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

40

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

41

Speaker adaptation using discriminative linear regression on time-varying mean parameters in trended HMM  

Microsoft Academic Search

In this letter, we report our recent work on applications of the combined maximum likelihood linear regression (MLLR) and the minimum classification error training (MCE) approach to estimating the time-varying polynomial Gaussian mean functions in the trended hidden Markov model (HMM). We call this integrated approach the minimum classification error linear regression (MCELR), which has been developed and implemented in

Rathinavelu Chengalvarayan

1998-01-01

42

Temperature and malaria trends in highland East Africa.  

PubMed

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

43

Urban Bias in Area-averaged Surface Air Temperature Trends.  

NASA Astrophysics Data System (ADS)

A data set derived from the United States Historical Climate Network has been compared to two global land-based temperature data sets that have been commonly cited in connection with the detection of the greenhouse effect and in other studies of climate change. Results indicate that in the United States the two global land-based temperature data sets have an urban bias between +6.1°C and +0.4°C over the twentieth century (1901-84). This bias is as large or larger than the overall temperature trend in the United States during this time period, +0.16°C/84 yr. Temperature trends indicate an increasing temperature from the turn of the century to the 1930s but a decrease thereafter. By comparison, the global temperature trends during the same period are between +0.4°C/84 yr and +0.6°C/84 yr. At this time, we can only speculate on the magnitude of the urban bias in the global land-based data sets for other parts of the globe, but the magnitude of the bias in the United States compared to the overall temperature trend underscores the need for a thorough global study.

Karl, Thomas R.; Jones, Philip D.

1989-03-01

44

Northern hemisphere temperature trends: A possible greenhouse gas effect  

SciTech Connect

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. An index designed to identify this signal has been computed from the station data. This index has positive trend at most of the stations, consistent with the greenhouse effect. Over the hemisphere, the signal is statistically significant. However, opposing temperature variations in the troposphere and stratosphere are associated with many other forcing mechanisms and the results cannot be used to identify a specific mechanism.

Karoly, D.J. (Princeton Univ., NJ (USA))

1989-05-01

45

Upper air temperature trends above Switzerland 1959-2011  

NASA Astrophysics Data System (ADS)

This study summarizes 53 years of radiosonde measurements at the MeteoSwiss Aerological Station of Payerne, Switzerland. The temperature time series is the result of a careful reassessment of the original data, mainly based on the internal station documentation. Comparisons with HadAT2 and RAOBCORE/RICH adjusted data sets document the high quality of our technical reevaluation. In the lower troposphere, we compare radiosonde measurement trends to independently homogenized surface trends measured at lowland and Alpine stations up to 3580 m. We find an average difference among trends below 0.03 K/decade (7-8%), showing consistency between upper air and surface temperature measurements. Upper air data show the 0°C isotherm to rise by about 70 m/decade on average over the whole period, which is consistent with the 60 m/decade trend found using surface measurements. A similar change has also been measured for the tropopause height, which rose by 54 m/decade over the last five decades. Analysis of the phase and amplitude of the diurnal temperature cycle shows a strongly decreasing amplitude with height from about 3 K at the surface to 0.2 K at 700 hPa. The diurnal cycle peaks at about 15 UTC at the surface and shifts to later hours with height, reaching almost midnight at 400 hPa. In the stratosphere, diurnal temperature again peaks at around 15 UTC, but with low amplitude. Annual temperature cycle amplitude is in the order of 15 K and fairly constant with height. The peak temperature, however, shifts from July-August in the troposphere to June-July in the stratosphere. Temperature trends in the troposphere exhibit a clear warming trend since the 1980s, which decreases with height and changes to a cooling trend in the stratosphere, with no trend or minor warming since the end of the 1990s. The warming in the troposphere is found to be larger during summer months, whereas the cooling in the stratosphere is larger during winter months.

Brocard, E.; Jeannet, P.; Begert, M.; Levrat, G.; Philipona, R.; Romanens, G.; Scherrer, S. C.

2013-05-01

46

Summer temperature trends in a Mediterranean area (Valencia region)  

NASA Astrophysics Data System (ADS)

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 the present, with the aim of characterising their evolution and detecting any trend towards a higher frequency of warmer days. First results indicate that in our study area there is indeed a higher frequency of days with tropical characteristics and persistent heat; in contrast, we found no tendency to exceed the records of absolute maximum temperatures.

Miró, J. J.; Estrela, M. J.; Millán, M.

2006-06-01

47

Interannual variations and trends in zonal mean series of total ozone, temperature, and zonal wind  

Microsoft Academic Search

The paper considers zonal mean (65° S–65° N, with a step of 5°) monthly mean NCEP\\/DOE reanalysis data on zonal wind and temperature\\u000a at levels of 20 to 100 mb and the TOMS data of version 8 on total ozone (TO) for the period 1979–2005. The results of calculating\\u000a linear-trend coefficients, correlation coefficients, and characteristic decay times and the data

K. N. Visheratin

2007-01-01

48

Stratospheric Temperature Trends from Small Rockets Between 1969-1995  

NASA Technical Reports Server (NTRS)

Between 1958-1995 a significant number of small meteorological rocketsondes were launched by United States (US) agencies from as many as 30 sites to as few as 3-4 sites in 1995. Stratospheric temperature trends were derived for many of the sites for the period 1969-1995. Similar long-term trends also were derived using rocketsondes launched from sites of the Former Soviet Union (FSU). The advantage of these two particular sets of rocket temperature measurements is the internal consistency of the data. All measurements were made with the same instrument, i.e., Datasonde in the case of the US sites and the M100B in the case of the FSU sites. Data from each instrument type were processed using its unique reduction method. Thus, all data were processed in the same manner including the method of applying corrections (necessary because of thermal heating of the thermistor from the high fall velocities experienced and from radiation effects). Straight-line least squares fit to the data made to monthly-mean measurements gave a downward change of 2-3 K per decade. A more complex fitting algorithm would have resulted in finer results but the straight-line fit was adequate for the analysis presented. Trend data are presented for 50 km, 40 km, and 25 km altitude levels. Trends for the US and FSU sites are quite similar. The 25km (50-hPa) level data are compared with radiosonde temperatures. Temperature trends over the 25-year period is different at each of the sites and not always in the same direction.

Schmidlin, F. J.

2000-01-01

49

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

50

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

51

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

52

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

53

Warming trends: Nonlinear climate change  

NASA Astrophysics Data System (ADS)

Most studies assume that temperature trends are linear. Now, research demonstrates that warming trends are nonlinear, that warming accelerated over most of the twentieth century and is much stronger since 1980 than calculated by linear methods.

Franzke, Christian L. E.

2014-06-01

54

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

55

The Impact of Urbanization on Global Surface Temperature Trends  

NASA Astrophysics Data System (ADS)

Rapid urbanization over the past half century has contributed to a warming bias in some Global Historical Climatological Network (GHCN) temperature records. The extent to which this urban warming bias contributes to global temperature trends remains largely unquantified both in raw and homogenized datasets, and no clear consensus exists on the need for specific urbanization corrections in global temperature reconstructions. In order to determine the magnitude of urbanization bias in the dataset, and to quantify the extent to which the newly adopted GHCN homogenization procedures correct for it, we examine minimum, maximum, and mean temperature trends from stations classified using numerous proxies for urbanity including MODIS, urban boundaries (GRUMP), satellite nightlights, and impermeable surface area, each created from publicly available high-resolution GIS datasets. These urbanity proxies are used to segment stations into separate urban and rural sets, and temperature differences between the two are calculated using both spatial gridding and station pairing approaches. The analysis is performed on raw and homogenized monthly data derived from the Global Historical Climatology Network (GHCN) Daily dataset that includes approximately 24,000 temperature measurement stations during the period from 1960 to present. Homogenized data that have been further adjusted using NASA GISS's Satellite Nightlight urban correction are also evaluated. The magnitude of the urbanization bias in the raw data and the degree to which this bias is mitigated with homogenization is discussed.

Hausfather, Z.; Mosher, S.; Menne, M. J.; Williams, C. N.; Stokes, N.; Jones, D.

2011-12-01

56

Room temperature giant and linear magnetoresistance in topological insulator Bi2Te3 nanosheets.  

PubMed

Topological insulators, a new class of condensed matter having bulk insulating states and gapless metallic surface states, have demonstrated fascinating quantum effects. However, the potential practical applications of the topological insulators are still under exploration worldwide. We demonstrate that nanosheets of a Bi(2)Te(3) topological insulator several quintuple layers thick display giant and linear magnetoresistance. The giant and linear magnetoresistance achieved is as high as over 600% at room temperature, with a trend towards further increase at higher temperatures, as well as being weakly temperature-dependent and linear with the field, without any sign of saturation at measured fields up to 13 T. Furthermore, we observed a magnetic field induced gap below 10 K. The observation of giant and linear magnetoresistance paves the way for 3D topological insulators to be useful for practical applications in magnetoelectronic sensors such as disk reading heads, mechatronics, and other multifunctional electromagnetic applications. PMID:23005006

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

2012-06-29

57

Room Temperature Giant and Linear Magnetoresistance in Topological Insulator Bi2Te3 Nanosheets  

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

58

On rising temperature trends at Dehradun in Doon valley of Uttarakhand, India  

NASA Astrophysics Data System (ADS)

Climate change is one of the most important issues among researchers, scientists, planners and politicians in the present times. Of all the climatic elements, temperature plays a major role in detecting climatic change brought about by urbanization and industrialization. This paper, therefore, attempts to study the temperature changes at Dehradun city by analyzing the time series data of annual maximum, minimum and mean temperature from 1967 to 2007. Data for the study has been analyzed in three parts by running linear regression and by taking anomalies for the whole period from 1967 to 2007, phase one 1967-1987 and phase two 1988-2007. The study of linear trend indicated increasing trends in annual maximum, annual minimum and annual mean temperatures. During 1967-2007 annual maximum, annual minimum and annual mean temperatures increased about 0.43°C, 0.38°C and 0.49°C, respectively. The analysis of temperature data in two phases also revealed an increase in annual maximum, annual minimum and annual mean temperature. However, temperature increase in second phase was more pronounced in relation to first phase. During second phase (1988-2007) annual maximum, annual minimum and annual mean temperatures increased about 0.42°C, 0.59°C and 0.54°C, respectively. The perceptible increase in temperature during second phase is mainly attributed to urbanization and industrialization process initiated at Dehradun particularly after becoming the state capital of newly carved out state of Uttarakhand since the year 2000. The analysis also highlight significantly the role of extreme vulnerability of rising temperatures at Dehradun and urban population will constantly be affected by the change in the temperature which controls the comfort level of the inhabitants. Also, the rising temperatures in Doon valley are not a healthy signature for crop production and water resources in the region.

Singh, Omvir; Arya, Poonam; Chaudhary, Bhagwan Singh

2013-06-01

59

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

60

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

61

Non-Linear Temperature Dependence in Graphene Nanoribbon Tunneling Transistors  

Microsoft Academic Search

It is usually assumed that tunneling current is fairly independent of temperature. By performing an atomistic transport simulation, we show, to the contrary, that the subthreshold tunneling current in a graphene nanoribbon (GNR) band-to-band tunneling transistor (TFET) should show significant and non-linear temperature dependence. Furthermore, the nature of this non-linearity changes as a function of source\\/drain doping and vertical electric

Youngki Yoon; Sayeef Salahuddin

2009-01-01

62

Bird population trends are linearly affected by climate change along species thermal ranges  

Microsoft Academic Search

Beyond the effects of temperature increase on local population trends and on species distribution shifts, how populations of a given species are affected by climate change along a species range is still unclear. We tested whether and how species responses to climate change are related to the populations locations within the species thermal range. We compared the average 20 year

F. Jiguet; V. Devictor; R. Ottvall; Turnhout Van C; H. P. Van der Jeugd; Å. Lindström

2010-01-01

63

Solar cycle signature and secular long-term trend in OH airglow temperature observations at South Pole, Antarctica  

Microsoft Academic Search

We have examined Michelson Interferometer OH airglow temperature data to investigate solar cycle and long-term variations of mesospheric temperatures at South Pole Station (SPS), Antarctica (90°S). The data set used here is continuous (24 hours a day) and taken during 1994-2004 austral winters. We have used a Multiple Linear Regression (MLR) technique to elucidate solar cycle and the trend term

S. M. I. Azeem; G. G. Sivjee; Y.-I. Won; Charles Mutiso

2007-01-01

64

Solar cycle signature and secular long-term trend in OH airglow temperature observations at South Pole, Antarctica  

Microsoft Academic Search

We have examined Michelson Interferometer OH airglow temperature data to investigate solar cycle and long-term variations of mesospheric temperatures at South Pole Station (SPS), Antarctica (90°S). The data set used here is continuous (24 hours a day) and taken during 1994–2004 austral winters. We have used a Multiple Linear Regression (MLR) technique to elucidate solar cycle and the trend term

S. M. I. Azeem; G. G. Sivjee; Y.-I. Won; Charles Mutiso

2007-01-01

65

Amplification of surface temperature trends and variability in thetropical atmosphere  

SciTech Connect

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

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

2005-08-11

66

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

67

Time trends in minimum mortality temperatures in Castile-La Mancha (Central Spain): 1975-2003  

NASA Astrophysics Data System (ADS)

The relationship between air temperature and human mortality is described as non-linear, with mortality tending to rise in response to increasingly hot or cold ambient temperatures from a given minimum mortality or optimal comfort temperature, which varies from some areas to others according to their climatic and socio-demographic characteristics. Changes in these characteristics within any specific region could modify this relationship. This study sought to examine the time trend in the maximum temperature of minimum organic-cause mortality in Castile-La Mancha, from 1975 to 2003. The analysis was performed by using daily series of maximum temperatures and organic-cause mortality rates grouped into three decades (1975-1984, 1985-1994, 1995-2003) to compare confidence intervals ( p < 0.05) obtained by estimating the 10-yearly mortality rates corresponding to the maximum temperatures of minimum mortality calculated for each decade. Temporal variations in the effects of cold and heat on mortality were ascertained by means of ARIMA models (Box-Jenkins) and cross-correlation functions (CCF) at seven lags. We observed a significant decrease in comfort temperature (from 34.2°C to 27.8°C) between the first two decades in the Province of Toledo, along with a growing number of significant lags in the summer CFF (1, 3 and 5, respectively). The fall in comfort temperature is attributable to the increase in the effects of heat on mortality, due, in all likelihood, to the percentage increase in the elderly population.

Miron, Isidro J.; Criado-Alvarez, Juan José; Diaz, Julio; Linares, Cristina; Mayoral, Sheila; Montero, Juan Carlos

2008-03-01

68

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

69

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

NASA Astrophysics Data System (ADS)

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 signals associated with the surface. The two primary MSU measures of tropospheric temperature contain different error characteristics and trends. The MSU channel 2 record exhibits a slight warming trend since 1979. Its broad vertical weighting function means that the temperature signal originates from throughout the troposphere and part of the lower stratosphere; intersatellite comparisons reveal low noise levels. Off-nadir channel 2 data are combined to provide an adjusted weighting function (called MSU 2R) without the stratospheric signal, but at a cost of an increased influence of surface emissions. Land surface microwave emissions, which account for about 20% of the total signal, depend on ground temperature and soil moisture and are subject to large variations associated with the diurnal cycle. The result is that MSU 2R noise levels are a factor of 3 larger than for MSU 2 and are sufficient to corrupt trends when several satellite records are merged.After allowing for physical differences between the satellite and surface records, large differences remain in temperature trends over the Tropics where there is a strong and deterministic coupling with the surface. The authors use linear regression with observed sea surface temperatures (SSTs) and an atmospheric general circulation model to relate the tropical MSU and surface datasets. These and alternative analyses of the MSU data, radiosonde data, and comparisons between the MSU 2R and channel 2 records, with estimates of their noise, are used to show that the downward trend in tropical MSU 2R temperatures is very likely spurious. Tropical radiosonde records are of limited use in resolving the discrepancies because of artificial trends arising from changes in instruments or sensors;however, comparisons with Australian radiosondes show a spurious downward jump in MSU 2R in mid-1991, which is not evident in MSU 2. Evaluation of reanalyzed tropical temperatures from the National Centers for Environmental Prediction and the European Centre for Medium-Range Weather Forecasts shows that they contain very different and false trends, as the analyses are only as good as the input database.Statistical analysis of the MSU 2R record objectively identifies two stepwise downward discontinuities that coincide with satellite transitions. The first is in mid-1981, prior to which only one satellite was in operation for much of the time so the diurnal cycle was not well sampled. Tropical SST anomalies over these years were small, in agreement with the Southern Oscillation index, yet the MSU 2R values were anomalously warm by 0.25°C. The second transition from NOAA-10 to NOAA-12 in mid-1991 did not involve an overlap except with NOAA-11, which suffered from a large drift in its equator-crossing times. MSU 2R anomalies have remained anomalously cold since mid-1991 by 0.1°C. Adding the two stepwise discontinuities to the tropical MSU 2R record allows it to be completely reconciled with the SST record within expected noise levels. The statistical results also make physical sense as the tropical satellite anomalies are magnified relative to SST anomalies by a factor of 1.3, which is the amplification expected following the saturated adiabatic lapse rate to the level of the peak weighting function of MSU 2R.

Hurrell, James W.; Trenberth, Kevin E.

1998-05-01

70

A spatial entropy analysis of temperature trends in the United States  

NASA Astrophysics Data System (ADS)

The United States Historical Climatology Network (USHCN) temperature database shows a significant upward trend over the past half century. In this investigation, we calculate the spatial entropy (dissimilarity or disorder) associated with the temperature trends of 1,221 stations in the fully adjusted USHCN. We find that over the network, the spatial entropy levels are significantly and positively related to the observed temperature trends suggesting that stations most unlike their neighbors in terms of temperature change tend to have a higher temperature trend than their neighbors. These results suggest that the USHCN contains some questionable warming signals at some stations, despite the many attempts to quantitatively control for these contaminants.

Balling, Robert C.; Roy, Shouraseni Sen

2004-05-01

71

CALL FOR PAPERS: Special issue on Current Trends in Integrability and Non Linear Phenomena Special issue on Current Trends in Integrability and Non Linear Phenomena  

NASA Astrophysics Data System (ADS)

This is a call for contributions to a special issue of Journal of Physics A: Mathematical and Theoretical dedicated to integrability and nonlinear phenomena. The motivation behind this special issue is to summarize in a single comprehensive publication, the main aspects (past and present), latest developments, different viewpoints and the directions being followed in this multidisciplinary field. We hope that such a special issue could become a particularly valuable reference for the broad scientific community working in integrability and nonlinear phenomena. Editorial policy The Editorial Board has invited D Gómez-Ullate, S Lombardo, M Mañas, M Mazzocco, F Nijhoff and M Sommacal to serve as Guest Editors for the special issue. Their criteria for the acceptance of contributions are as follows. The subject of the paper should relate to the following list of subjects: Integrable systems (including quantum and discrete) and applications Dynamical systems: Hamiltonian systems and dynamics in the complex domain Nonlinear waves, soliton equations and applications Nonlinear ODEs including Painlevé equations and isomonodromic deformations Symmetries and perturbative methods in the classification of integrable PDEs Infinite dimensional Lie algebras and integrable systems Orthogonal Polynomials, Random Matrix Theory All contributions will be refereed and processed according to the usual procedure of the journal. Papers should report original and significant research that has not already been published. Guidelines for preparation of contributions The DEADLINE for contributed papers will be 28 February 2010. This deadline will allow the special issue to appear in October 2010. There is a nominal page limit of 15 printed pages per contribution (invited review papers can be longer). For papers exceeding this limit, the Guest Editors reserve the right to request a reduction in length. Further advice on publishing your work in Journal of Physics A: Mathematical and Theoretical may be found at www.iop.org/Journals/jphysa. Contributions to the special issue should if possible be submitted electronically by web upload at www.iop.org/Journals/jphysa, or by email to jphysa@iop.org, quoting 'JPhysA Special Issue: Current Trends in Integrability and Non Linear Phenomena' Submissions should ideally be in standard LaTeX form. Please see the website for further information on electronic submissions. Authors unable to submit electronically may send hard-copy contributions to: Publishing Administrators, Journal of Physics A, IOP Publishing, Dirac House, Temple Back, Bristol BS1 6BE, UK. Please quote 'JPhysA Special Issue—Current Trends in Integrability and Non Linear Phenomena'. All contributions should be accompanied by a read-me file or covering letter giving the postal and e-mail addresses for correspondence. The Publishing Office should be notified of any subsequent change of address. This special issue will be published in the paper and online version of the journal.

Gómez-Ullate, D.; Lombardo, S.; Mañas, M.; Mazzocco, M.; Nijhoff, F.; Sommacal, M.

2009-11-01

72

On summary measure analysis of linear trend repeated measures data: performance comparison with two competing methods  

PubMed Central

Background The summary measure approach (SMA) is sometimes the only applicable tool for the analysis of repeated measurements in medical research, especially when the number of measurements is relatively large. This study aimed to describe techniques based on summary measures for the analysis of linear trend repeated measures data and then to compare performances of SMA, linear mixed model (LMM), and unstructured multivariate approach (UMA). Methods Practical guidelines based on the least squares regression slope and mean of response over time for each subject were provided to test time, group, and interaction effects. Through Monte Carlo simulation studies, the efficacy of SMA vs. LMM and traditional UMA, under different types of covariance structures, was illustrated. All the methods were also employed to analyze two real data examples. Results Based on the simulation and example results, it was found that the SMA completely dominated the traditional UMA and performed convincingly close to the best-fitting LMM in testing all the effects. However, the LMM was not often robust and led to non-sensible results when the covariance structure for errors was misspecified. The results emphasized discarding the UMA which often yielded extremely conservative inferences as to such data. Conclusions It was shown that summary measure is a simple, safe and powerful approach in which the loss of efficiency compared to the best-fitting LMM was generally negligible. The SMA is recommended as the first choice to reliably analyze the linear trend data with a moderate to large number of measurements and/or small to moderate sample sizes.

2012-01-01

73

Homogenization of Chinese daily surface air temperatures and analysis of trends in the extreme temperature indices  

NASA Astrophysics Data System (ADS)

This study first homogenizes time series of daily maximum and minimum temperatures recorded at 825 stations in China over the period from 1951 to 2010, using both metadata and the penalized maximum t test with the first-order autocorrelation being accounted for to detect change points and using the quantile-matching algorithm to adjust the data time series to diminish discontinuities. Station relocation was found to be the main cause for discontinuities, followed by station automation. The effects of discontinuities on estimation of long-term trends in the annual mean and extreme indices of temperature are illustrated. The data homogenization is shown to have improved the spatial consistency of estimated trends. Using the homogenized daily minimum and daily maximum temperature data, this study also analyzes trends in extreme temperature indices. The results show that the vast majority (85%-90%) of the 825 sites have experienced significantly more warm nights and less cold nights since 1951. There have also been more warm days and less cold days since 1951, although these trends are less extensive. About 62% of the 825 sites were found to have experienced significantly more warm days and about 50% significantly less cold days. None of the 825 sites were found to have significantly more cold nights/days or less warm nights/days. These indicate that the warming is stronger in nighttime than in daytime and stronger in winter than in summer. Thus, the diurnal temperature range was found to have significantly decreased at 49% of the 825 sites, with significant increases being identified only at 3% of these sites.

Xu, Wenhui; Li, Qingxiang; Wang, Xiaolan L.; Yang, Su; Cao, Lijuan; Feng, Yang

2013-09-01

74

Linear and nonlinear responses to middle latitude surface temperature anomalies  

NASA Technical Reports Server (NTRS)

Nonlinear responses to fixed and seasonally varying surface temperature anomalies in a two-level hemispheric time-dependent coupled atmosphere-surface mixed layer model are described. Linear stationary models that are equivalent to the nonlinear time-dependent model are used to analyze these responses. A model linearized around the climatological zonal state of the time dependent model and forced by anomalous surface temperatures does not provide a reasonable estimate for the anomalous reponses, which are considerably underestimated. Better responses are obtained when the anomalous stationary nonlinear eddy fluxes are included in a model linearized around the full climatology. However, this latter model is overly sensitive, and anomalous responses are a small residual balance to the forcing by the surface temperature anomalies and the anomalous transient eddy fluxes. To better understand these linear responses, an eigenanalysis of the climatological state is performed. Seasonal anomalies appear to be dominated by one characteristic pattern near resonance which can be associated with a slowly growing coupled atmosphere-ocean instability.

Roads, John O.

1989-01-01

75

Halide and hydroxide linearly bridged bimetallic copper(II) complexes: trends in strong antiferromagnetic superexchange interactions.  

PubMed

Centrosymmetric [Cu(2)(?-X)(?-L(m)*)(2)](ClO(4))(3) (X = F(-), Cl(-), Br(-), OH(-), L(m)* = m-bis[bis(3,5-dimethyl-1-pyrazolyl)methyl]benzene)], the first example of a series of bimetallic copper(II) complexes linked by a linearly bridging mononuclear anion, have been prepared and structurally characterized. Very strong antiferromagnetic exchange coupling between the copper(II) ions increases along the series F(-) < Cl(-) < OH(-) < Br(-), where -J = 340, 720, 808, and 945 cm(-1). DFT calculations explain this trend by an increase in the energy along this series of the antibonding antisymmetric combination of the p orbital of the bridging anion interacting with the copper(II) d(z(2)) orbital. PMID:22834975

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

2012-08-01

76

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

77

An examination of 1997-2007 surface layer temperature trends at two heights in Oklahoma  

NASA Astrophysics Data System (ADS)

This study assesses near surface lapse rates and temperatures over the past decade at two heights from the Oklahoma Mesonet. A statistically significant change in lapse rate was detected of -0.21 +/- 0.09°C (10 m)-1 per decade. The trend of nighttime lapse rate was about three times larger than the magnitude of trend of the daytime lapse rate. The lapse rate trends at the time of the daily maximum and minimum temperatures were larger during calm conditions. Significantly, changes of temperature trends at a single height were inconclusive when the data was not segmented by wind speed classes. For daily maximum and minimum station series at two heights, the temperature trends of these station series were the largest for daily minimum temperature at 1.5 m under calm conditions, and the second largest for daily minimum temperatures at 9.0 m under calm conditions. These observations document that monitoring long term near-surface daily minimum temperature trends at a single level on light wind nights will not produce the same trends as for long term temperature trends at other heights near the surface.

Lin, X.; Pielke, R. A.; Hubbard, K. G.; Crawford, K. C.; Shafer, M. A.; Matsui, T.

2007-12-01

78

Sensitivity of Tropospheric and Stratospheric Temperature Trends to Radiosonde Data Quality  

Microsoft Academic Search

Radiosonde data have been used, and will likely continue to be used, for the detection of temporal trends in tropospheric and lower-stratospheric temperature. However, the data are primarily operational observations, and it is not clear that they are of sufficient quality for precise monitoring of climate change. This paper explores the sensitivity of upper-air temperature trend estimates to several data

Dian J. Gaffen; Michael A. Sargent; R. E. Habermann; John R. Lanzante

2000-01-01

79

Effects of ozone and well-mixed gases on annual-mean stratospheric temperature trends  

NASA Astrophysics Data System (ADS)

The effects of changes in ozone and well-mixed greenhouse gases upon the annual-mean stratospheric temperatures are investigated using a general circulation model and compared with the observed (1979-2000) trends. In the global-mean lower stratosphere (50-100 hPa), ozone changes exert the most important influence upon the cooling trend. In the upper stratosphere, where both ozone and greenhouse gas changes influence the temperature trends, the amount of cooling is sensitive to the background ozone climatology. Taking into account the uncertainties in the observed temperature trend estimates and the dynamical variability of the model, the simulated results are in reasonable quantitative agreement with the vertical profile of the observed global-and-annual-mean stratospheric cooling, and with the observed lower stratospheric zonal-and-annual-mean cooling. This affirms the major role of these species in the temperature trend of the stratosphere over the past two decades.

Ramaswamy, V.; Schwarzkopf, M. D.

2002-11-01

80

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

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

81

Northern Hemisphere extratropical circulation anomalies and recent January land surface temperature trends  

Microsoft Academic Search

This study demonstrates that long-term January temperature trends in the Northern Hemisphere are strongly related to decadal-scale variations in extratropical mid-tropospheric circulation modes. Circulation indices derived from a rotated principal components analysis of 500-mb geopotential heights explain 72% of the January Northern Hemisphere land surface air temperature variance. An analysis of the spatial characteristics of January temperature trends from 1966

Michael A. Palecki; Daniel J. Leathers

1993-01-01

82

Northern hemisphere extratropical circulation anomalies and recent January land surface temperature trends  

Microsoft Academic Search

This study demonstrates that long-term January temperature trends in the Northern Hemisphere are strongly related to decadal-scale variations in extratropical mid-tropospheric circulation modes. Circulation indices derived from a rotated principal components analysis of 500-mb geopotential heights explain 72% of the January Northern Hemisphere land surface air temperature variance. An analysis of the spatial characteristics of January temperature trends from 1966

Michael A. Palecki; Daniel J. Leathers

1993-01-01

83

Design and laboratory testing of a prototype linear temperature sensor  

NASA Astrophysics Data System (ADS)

This report discusses the basic theory, design, and laboratory testing of a prototype linear temperature sensor (or "line sensor'), which is an instrument for measuring internal waves in the ocean. The operating principle of the line sensor consists of measuring the average resistance change of a vertically suspended wire (or coil of wire) induced by the passage of an internal wave in a thermocline. The advantage of the line sensor over conventional internal wave measurement techniques is that it is insensitive to thermal finestructure which contaminates point sensor measurements, and its output is approximately linearly proportional to the internal wave displacement. An approximately one-half scale prototype line sensor module was teste in the laboratory. The line sensor signal was linearly related to the actual fluid displacement to within 10%. Furthermore, the absolute output was well predicted (within 25%) from the theoretical model and the sensor material properties alone. Comparisons of the line sensor and a point sensor in a wavefield with superimposed turbulence (finestructure) revealed negligible distortion in the line sensor signal, while the point sensor signal was swamped by "turbulent noise'. The effects of internal wave strain were also found to be negligible.

Dube, C. M.; Nielsen, C. M.

1982-07-01

84

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

85

Cooling trend of the tropical cold point tropopause temperatures and its implications  

Microsoft Academic Search

Operational sounding data (1973-1998) were used to determine cold point tropopause (CPT) characteristics. A cooling trend (-0.57+\\/-0.06K\\/Decade during 1973-1998) in tropical CPT temperatures has been found, which is opposite to what has been hypothesized to explain the trend in stratospheric water vapor. Given this trend, the annual averages of the CPT saturation mixing ratios (SMRs) inferred from the analysis of

Xue-Long Zhou; Marvin A. Geller; Minghua Zhang

2001-01-01

86

A linear regression-based study for temperature sensitivity analysis of Iran electrical load  

Microsoft Academic Search

In this paper sensibility of Iran network load to the temperature has been studied by the linear regression method. The linear regression analysis of Iranpsilas electrical load recognizes that the load pattern is heavily dependent on temperature, and finds a linear function between the load and the networkpsilas temperature. This study shows that temperature has a great effect on Iranpsilas

S. M. Moghaddas-Tafreshi; Mahdi Farhadi

2008-01-01

87

Trend analysis of maximum, minimum, and average temperatures in Bangladesh: 1961-2008  

NASA Astrophysics Data System (ADS)

The present study is about the analysis of mean maximum and mean minimum temperatures carried out on annual, seasonal, and monthly timescales examining the data from 15 meteorological stations in Bangladesh for the period 1961-2008. Various spatial and statistical tools were used to display and analyze trends in temperature data. ArcGIS was used to produce the spatially distributed temperature data by using Thiessen polygon method. The nonparametric Mann-Kendall test was used to determine whether there is a positive or negative trend in data with their statistical significance. Sen's method was also used to determine the magnitude of the trends. The results reveal positive trends in annual mean and mean maximum temperatures with 95 % significance. Trend test reveals that the significant positive trend is found in June to November in case of mean maximum temperature, but according to the mean minimum temperature, the situation is different and a significant positive trend was found from November to February. The analysis of the whole record reveals a tendency toward warmer years, with significantly warmer summer periods and slightly colder winters. These warming patterns may have important impacts on energy consumption, water supply, human health, and natural environment in Bangladesh.

Siddik, Md. Abu Zafer; Rahman, Mursheda

2014-05-01

88

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

89

Solar cycle signature and secular long-term trend in OH airglow temperature observations at South Pole, Antarctica  

NASA Astrophysics Data System (ADS)

We have examined Michelson Interferometer OH airglow temperature data to investigate solar cycle and long-term variations of mesospheric temperatures at South Pole Station (SPS), Antarctica (90°S). The data set used here is continuous (24 hours a day) and taken during 1994-2004 austral winters. We have used a Multiple Linear Regression (MLR) technique to elucidate solar cycle and the trend term in the MI temperature time series data. The 11-year time series of OH rotational temperature shows a strong correlation with F10.7 radio flux (R = 0.60). The amplitude of solar cycle response seen in the mesopause temperature records at South Pole is about 0.04 ± 0.01 K/sfu (Solar Flux Units), however, the trend term is statistically insignificant and is about 0.1 ± 0.2 K/year. Superposed epoch studies have been carried out in order to determine climatological variations in OH temperatures above South Pole derived from 11 years of austral winter observations. The mean amplitude of this variation is about 12.6 K and its maximum occurs near 30 May which is in agreement with the Fabry-Perot Spectrometer (FPS) observations of OH temperatures at SPS (Hernandez, 2003). However, whereas Hernandez (2003) reported 35 K cooling in 2002, MI OH temperatures at SPS do not show any significant deviation from previous years.

Azeem, S. M. I.; Sivjee, G. G.; Won, Y.-I.; Mutiso, Charles

2007-01-01

90

Is the World Ocean Warming? Upper-Ocean Temperature Trends: 1950 2000  

Microsoft Academic Search

Subsurface temperature trends in the better-sampled parts of the World Ocean are reported. Where there are sufficient observations for this analysis, there is large spatial variability of 51-yr trends in the upper ocean, with some regions showing cooling in excess of 3°C, and others warming of similar magnitude. Some 95% of the ocean area analyzed has both cooled and warmed

D. E. Harrison; Mark Carson

2007-01-01

91

Review of trend detection methods and their application to detect temperature changes in India  

NASA Astrophysics Data System (ADS)

SummaryPresent study performs the spatial and temporal trend analysis of annual, monthly and seasonal maximum and minimum temperatures (tmax, tmin) in India. Recent trends in annual, monthly, winter, pre-monsoon, monsoon and post-monsoon extreme temperatures (tmax, tmin) have been analyzed for three time slots viz. 1901-2003, 1948-2003 and 1970-2003. For this purpose, time series of extreme temperatures of India as a whole and seven homogeneous regions, viz. Western Himalaya (WH), Northwest (NW), Northeast (NE), North Central (NC), East coast (EC), West coast (WC) and Interior Peninsula (IP) are considered. Rigorous trend detection analysis has been exercised using variety of non-parametric methods which consider the effect of serial correlation during analysis. During the last three decades minimum temperature trend is present in All India as well as in all temperature homogeneous regions of India either at annual or at any seasonal level (winter, pre-monsoon, monsoon, post-monsoon). Results agree with the earlier observation that the trend in minimum temperature is significant in the last three decades over India (Kothawale et al., 2010). Sequential MK test reveals that most of the trend both in maximum and minimum temperature began after 1970 either in annual or seasonal levels.

Sonali, P.; Nagesh Kumar, D.

2013-01-01

92

On the estimation of external trends in minimum, maximum and mean temperature records over China  

NASA Astrophysics Data System (ADS)

We consider minimum, maximum, and mean temperature records at 112 station in China and use a recent scaling approach by [Lennartz and Bunde, 2011] to estimate the minimum external trend over the past 50 years, for confidence probabilities 0.95 and 0.99. We find that the minimum temperatures, in contrast to the maximum temperatures, show a significant trend for almost all considered stations. We also study the trend as a function of the population (in 2008) and of the population increase in the past 50 years. We find a significant increase in the trend of the minimum temperature at stations with a large population increase, which suggests that part of the recent warming may be due to urban heat islands.

Yuan, N.; Bunde, A.; Fu, Z.

2012-04-01

93

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

NASA Astrophysics Data System (ADS)

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

Black, Adam Leland

94

Precise monitoring of global temperature trends from satellites  

Microsoft Academic Search

Passive microwave radiometry from satellites provides more precise atmospheric temperature information than that obtained from the relatively sparse distribution of thermometers over the earth's surface. Accurate global atmospheric temperature estimates are needed for detection of possible greenhouse warming, evaluation of computer models of climate change, and for understanding important factors in the climate system. Analysis of the first 10 years

R. W. Spencer; J. R. Christy

1990-01-01

95

A spatiotemporal analysis of U.S. station temperature trends over the last century  

NASA Astrophysics Data System (ADS)

This study presents a nonlinear spatiotemporal analysis of 1167 station temperature records from the United States Historical Climatology Network covering the period from 1898 through 2008. We use the empirical mode decomposition method to extract the generally nonlinear trends of each station. The statistical significance of each trend is assessed against three null models of the background climate variability, represented by stochastic processes of increasing temporal correlation length. We find strong evidence that more than 50% of all stations experienced a significant trend over the last century with respect to all three null models. A spatiotemporal analysis reveals a significant cooling trend in the South-East and significant warming trends in the rest of the contiguous U.S. It also shows that the warming trend appears to have migrated equatorward. This shows the complex spatiotemporal evolution of climate change at local scales.

Capparelli, V.; Franzke, C.; Vecchio, A.; Freeman, M. P.; Watkins, N. W.; Carbone, V.

2013-07-01

96

A spatio-temporal analysis of US station temperature trends over the last century  

NASA Astrophysics Data System (ADS)

This study presents a nonlinear spatio-temporal analysis of 1167 station temperature records from the United States Historical Climatology Network covering the period from 1898 through 2008. We use the Empirical Mode Decomposition (EMD) method to extract the generally nonlinear trends of each station. The statistical significance of each trend is assessed against three null models of the background climate variability, represented by stochastic processes of increasing temporal correlation length. We find strong evidence that more than 50 percent of all stations experienced a significant trend over the last century with respect to all three null models. A spatio-temporal analysis reveals a significant cooling trend in the South-East and significant warming trends in the rest of the contiguous US. It also shows that the warming trend appears to have migrated equatorward and possibly also in altitude. This shows the complex spatio-temporal evolution of climate change at local scales

Capparelli, Vincenzo; Franzke, Christian; Vecchio, Antonio; Freeman, Mervyn P.; Watkins, Nicholas W.; Carbone, Vincenzo

2013-04-01

97

Non-linear saturation mechanism of electron temperature gradient modes  

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

98

Non-linear saturation mechanism of electron temperature gradient modes  

SciTech Connect

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

Tokluoglu, E. K.; Sokolov, V.; Sen, A. K. [Plasma Physics Laboratory, Columbia University, New York, New York 10027 (United States)

2012-10-15

99

How Certain are Temperature Trend Estimates in the Lower Stratosphere?  

NASA Technical Reports Server (NTRS)

Many recent studies have shown a clear cooling of the lower stratosphere, which has often been coupled to decreases in the local ozone concentrations as well as increases in well-mixed gases and aerosols. While satellite data are available over about two decades, radiosonde estimates give longer time series for analysis. Trend detection is limited by the long-term stability of the measurement systems and the existence of large interannual variability forced by dynamics. In this paper, both of these issues will be addressed critically, with emphasis on localized changes and how these may relate to disruptions in observation systems and the dynamical forcing mechanisms. The primary dataset for the study are the northern hemispheric analyses from the Free University of Berlin, which will be supplemented by a variety of other sources and some model experiments.

Pawson, Steven

1998-01-01

100

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

NASA Astrophysics Data System (ADS)

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

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

2001-11-01

101

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

USGS Publications Warehouse

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

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

2002-01-01

102

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

103

Sea Surface Temperature Trends of the Gulf Stream  

NSDL National Science Digital Library

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. In this three-part lesson, students will 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. The lesson provides detailed procedure, related links, sample graphs, follow-up questions, extensions, and teacher notes.

2006-10-31

104

The Effects of Global Warming on Temperature and Precipitation Trends in Northeast America  

NASA Astrophysics Data System (ADS)

The objective of this paper is to discuss the analysis of results in temperature and precipitation (rainfall) data and how they are affected by the theory of global warming in Northeast America. The topic was chosen because it will show the trends in temperature and precipitation and their relations to global warming. Data was collected from The Global Historical Climatology Network (GHCN). The data range from years of 1973 to 2012. We were able to calculate the yearly and monthly regress to estimate the relationship of variables found in the individual sources. With the use of specially designed software, analysis and manual calculations we are able to give a visualization of these trends in precipitation and temperature and to question if these trends are due to the theory of global warming. With the Calculation of the trends in slope we were able to interpret the changes in minimum and maximum temperature and precipitation. Precipitation had a 9.5 % increase over the past forty years, while maximum temperature increased 1.9 %, a greater increase is seen in minimum temperature of 3.3 % was calculated over the years. The trends in precipitation, maximum and minimum temperature is statistically significant at a 95% level.

Francis, F.

2013-12-01

105

Temperature Trends in Sacramento--Another Heat Island.  

National Technical Information Service (NTIS)

The study of the temperature regime at Sacramento, which has a long period of record (90 years), provides additional evidence supporting the heat island concept. This is especially true when compared to similar data from the University of California at Da...

A. D. Lentini

1969-01-01

106

External Resource: Surface Air Temperature Trends of the Caribbean  

NSDL National Science Digital Library

This activity allows learners/students to use real satellite data to determine the changes in near-surface air temperature at different times of the year over the Caribbean Sea. Upon completion of the activity, learners should be able to state how Earth's

1900-01-01

107

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

108

Amplification of surface temperature trends and variability in thetropical atmosphere  

Microsoft Academic Search

The month-to-month variability of tropical temperatures is larger in the troposphere than at the Earth's surface. This amplification behavior is similar in a range of observations and climate model simulations, and is consistent with basic theory. On multi-decadal timescales, tropospheric amplification of surface warming is a robust feature of model simulations, but occurs in only one observational dataset. Other observations

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

2005-01-01

109

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  

NASA Astrophysics Data System (ADS)

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-term data 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 L.; Dunham, Jason B.; Haggerty, Roy; Hockman-Wert, David

2012-05-01

110

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

USGS Publications Warehouse

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

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

2012-01-01

111

Relationship between ozone and temperature trends in the lower stratosphere: Latitude and seasonal dependences  

NASA Technical Reports Server (NTRS)

A one-dimensional radiative transfer model with fixed dynamical heating is used to calculate the approximate latitude and seasonal dependences of lower stratospheric temperature changes associated with observed ozone trends. The spatial and temporal distribution of ozone profile trends in the lower stratosphere is estimated from a combination of Nimbus 7 Solar Backscattered Ultraviolet (SBUV) global measurements of the ozone column below 32 mbar for the period 1979-1990 and balloon ozonesonde profile trends at northern middle latitudes. The calculated temperature trends near 100 mbar compare favorably with those recently derived by Randel and Cobb (1994) using data from Channel 4 of the Microwave Sounding Unit (MSU) on the NOAA operational satellites, although a number of quantitative differences are found. An independent analysis reported here of 100 mbar temperatures derived from northern hemisphere radiosonde data at the Free University of Berlin (FUB) supports the validity of the satellite-derived lower stratospheric temperature trends. These results are therefore generally consistent with the hypothesis that observed lower stratospheric cooling trends are predominantly determined by reductions in radiative heating associated with stratospheric ozone depletion.

Mccormack, John P.; Hood, Lon L.

1994-01-01

112

Investigation of the low-temperature performance of asphalt mixtures via fatigue and linear contraction and creep test  

NASA Astrophysics Data System (ADS)

Three types of asphalt mixtures, including asphalt concrete (AC), stone mastic asphalt (SMA) and porous asphalt (PA) with a 13mm gradation, are chosen to study the fatigue behavior, linear contraction and creep performance of them. The analysis of the experimental results is summarized as follows. The asphalt mixture exhibits longer fatigue life at low temperature than that at high temperature. But the fatigue life is more sensitive to the loading stress at low temperature. At the same time, the fatigue lives of all the three mixture gradations show decreasing trends with the increasing stress, which implies that restraining over-loading of highways is quite important. The linear contractive quotiety shows great distinction with the types of asphalt mixture gradations and temperature span, which indicates that modified asphalt and lower air voids can benefit to the contractive properties of asphalt mixtures at low temperature. Additionally, the linear contractive quotiety decreases with the falling of the temperature, meanwhile the distinctions between different temperature spans tend to slower. The creep test indicates that lower air voids and larger asphalt content are beneficial to the low temperature performance of asphalt.

Liu, Conghui; Wu, Shaopeng; Li, Bo; Wang, Jingang

2008-11-01

113

Effect of data homogenization on estimate of temperature trend: a case of Huairou station in Beijing Municipality  

NASA Astrophysics Data System (ADS)

Daily minimum temperature (Tmin) and maximum temperature (Tmax) data of Huairou station in Beijing from 1960 to 2008 are examined and adjusted for inhomogeneities by applying the data of two nearby reference stations. Urban effects on the linear trends of the original and adjusted temperature series are estimated and compared. Results show that relocations of station cause obvious discontinuities in the data series, and one of the discontinuities for Tmin are highly significant when the station was moved from downtown to suburb in 1996. The daily Tmin and Tmax data are adjusted for the inhomogeneities. The mean annual Tmin and Tmax at Huairou station drop by 1.377°C and 0.271°C respectively after homogenization. The adjustments for Tmin are larger than those for Tmax, especially in winter, and the seasonal differences of the adjustments are generally more obvious for Tmin than for Tmax. Urban effects on annual mean Tmin and Tmax trends are -0.004°C/10 year and -0.035°C/10 year respectively for the original data, but they increase to 0.388°C/10 year and 0.096°C/10 year respectively for the adjusted data. The increase is more significant for the annual mean Tmin series. Urban contributions to the overall trends of annual mean Tmin and Tmax reach 100% and 28.8% respectively for the adjusted data. Our analysis shows that data homogenization for the stations moved from downtowns to suburbs can lead to a significant overestimate of rising trends of surface air temperature, and this necessitates a careful evaluation and adjustment for urban biases before the data are applied in analyses of local and regional climate change.

Zhang, Lei; Ren, Guo-Yu; Ren, Yu-Yu; Zhang, Ai-Ying; Chu, Zi-Ying; Zhou, Ya-Qing

2013-04-01

114

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

Microsoft Academic Search

This paper documents various unresolved issues in using surface temperature trends as a metric for assessing global and regional climate change. A series of examples ranging from errors caused by temperature measurements at a monitoring station to the undocumented biases in the regionally and globally averaged time series are provided. The issues are poorly understood or documented and relate to

Roger A. Pielke Sr; Christopher A. Davey; Dev Niyogi; Souleymane Fall; Jesse Steinweg-Woods; Ken Hubbard; Xiaomao Lin; Ming Cai; Young-Kwon Lim; Hong Li; John Nielsen-Gammon; Kevin Gallo; Rezaul Mahmood; Stuart Foster; Richard T. McNider; Peter Blanken

2007-01-01

115

Trends and Variations in South Pacific Island and Ocean Surface Temperatures  

Microsoft Academic Search

An analysis of temperature variability and trends in the South Pacific, mainly in the twentieth century, using data from 40 island stations and optimally interpolated sea surface and night marine air temperature data is presented. The last-named dataset is new and contains improved corrections for changes in the height of thermometer screens as ships have become larger. It is shown

C. K. Folland; M. J. Salinger; N. Jiang; N. A. Rayner

2003-01-01

116

Trends and Variations in South Pacific Island and Ocean Surface Temperatures  

Microsoft Academic Search

An analysis of temperature variability and trends in the South Pacific, mainly in the twentieth century, using data from 40 island stations and optimally interpolated sea surface and night marine air temperature data is presented. The last-named dataset is new and contains improved corrections for changes in the height of ther- mometer screens as ships have become larger. It is

C. K. Folland; M. J. Salinger; N. Jiang; N. A. Rayner

2003-01-01

117

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

SciTech Connect

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

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

2007-07-01

118

Trends in ozone and temperature structure: comparison of theory and measurements  

SciTech Connect

Comparison of model calculated trends in ozone and temperature due to inferred variations in trace gas concentrations and solar flux, is made with available analyses of observations. In general, the calculated trends in total ozone and the vertical ozone distribution agree well with the measured trends. However, there are too many remaining theoretical and sampling uncertainties to establish causality. Although qualitatively in agreement, the observed temperature decrease in the upper stratosphere is significantly larger than that calculated. Theoretical results suggest a significant influence on stratospheric ozone from solar flux variations, but observational evidence is at best inconclusive. Overall, the trend comparisons tend to be consistent with the hypothesis that several different anthropogenic influences are affecting the present global atmosphere. 7 references, 3 figures, 2 tables.

Wuebbles, D.J.

1984-08-01

119

Non-linear dielectric response of glass formers under oscillating temperature  

NASA Astrophysics Data System (ADS)

Exploiting a simple model we investigate linear and non-linear dielectric responses of glass formers under oscillating temperature. We demonstrate that three characteristic temperatures, Vogel-Fulcher, glass transition and cross-over temperatures, can be determined from the analysis of the dielectric response. We first show that the real part of the linear susceptibility at the static limit becomes a cusp below the cross-over temperature and its curvature changes at the glass transition temperature. We also analyze the non-linear susceptibility under oscillating temperature which contains information of the response of the system, in particular of the free energy landscape, against the temperature modulation. We find that the real part of the non-linear susceptibility shows anomalies at the characteristic temperatures similar to the linear susceptibility.

Odagaki, Takashi; Kuroda, Masatoshi; Katoh, Hideaki; Saruyama, Yasuo

2012-02-01

120

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.

121

On the estimation of minimum anthropogenic trends in regional averaged temperature records over China  

NASA Astrophysics Data System (ADS)

In order to evaluate and compare possible anthropogenic trends in China, we study in the 8 climate regions of China the averaged minimum, maximum, and mean temperatures over the past 50 years. For obtaining the temperature data, we averaged over a large number of local temperature data in each climate zone. The climate regions are the Northeast, North, East, Southcentral, Southern, Southwest, and Northwest as well as the province of Xinjiang. In order to estimate the minimum anthropogenic trend (MAT) in each climate zone within the 95 percent confidence interval we use the methodology of Lennartz and Bunde [1]. We find that the averaged temperature data show a considerably more pronounced anthropogenic signal than the local temperatures. For the averaged minimum temperatures, the MAT varies from 0.320C in Southwest up to 1.510C in Xinjiang, for the averaged mean temperatures, the MAT varies from -0.060C in Southwest up to 1.050C in North, and for the averaged maximum temperature the MAT varies from -1.140C in Southcentral up to 0.680C in Northwest. While all averaged minimum temperatures show a significant external trend, the averaged mean temperature of Southwest and the maximum temperatures from the southern regions of China (Southwest, Southern, and Southcentral) do not show a significant anthropogenic signal, since their MAT is negative. If we average over all climatic zones in China, the MAT is positive not only for the minimum temperature (1.000C), but also for the mean (0.710C) and the maximum temperature (0.350C). [1] Lennartz. S., and A. Bunde (2011), Distribution of natural trends in long-term correlated records: A scaling approach, Phys. Rev. E, 84, 021129.

Yuan, N.; Bunde, A.

2012-04-01

122

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

NASA Astrophysics Data System (ADS)

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

Franquist, Eric S.

123

Trends in the mesopause region temperature and our present understanding—an update  

NASA Astrophysics Data System (ADS)

A comprehensive review of the long-term changes and trends in the thermal structure of the mesosphere and lower thermosphere (MLT) region has been provided by Beig et al. [Beig, G., Keckhut, P., Lowe, R.P., Roble, R.G., Mlynczak, M.G., Scheer, J., Fomichev, V.I., Offermann, D., French, W.J.R., Shepherd, M.G., Semenov, A.I., Remsberg, E.E., She, C.Y., Lübken, F.J., Bremer, J., Clemesha, B.R., Stegman, J., Sigernes, F., Fadnavis, S., 2003. Review of mesospheric temperature trends. Rev. Geophys. 41 (4), 1015, doi: 10.1029/2002RG000121] in which results and analysis reported until about early 2002 were included. Since then not much new information on the temperature trends has been added. Nevertheless, some new results along with some modified results by revisiting the older data sets have been reported in recent time. Our understanding on the nature of temperature trends in the MLT region is relatively better understood now and model agreements with some of the specific observed feature are better reproduced in recent time. This paper briefly summarizes the progress made over the recent past in the field of mesopause region temperature trends and provide an update to Beig et al. (2003). Some new information is also added in recent time on the seasonal trend variability in temperature of the mesopause region which is also discussed in this article. Finally the new insight into the probable mechanisms to understand the observed trends along with future scope of the work in this field is outlined.

Beig, Gufran

124

Using Limited Time Periods as a Means to Elucidate Microwave Sounding Unit Derived Tropospheric Temperature Trend Methods.  

National Technical Information Service (NTIS)

Limited Time Period (LTP) running trends are used to elucidated Microwave Sounding Unit (MSU) derived tropospheric temperature trend methods. Regression derived coefficients were used to combine lower stratosphere (LS) and mid-troposphere to lower stratos...

R. M. Randall

2007-01-01

125

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

NASA Astrophysics Data System (ADS)

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

Gröcke, D.; Ufnar, D.; Beddows, P. A.

2007-12-01

126

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

127

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

Microsoft Academic Search

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

Robin T. Clarke

2002-01-01

128

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

129

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

NASA Astrophysics Data System (ADS)

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

Guo, Lidan; Xia, Ziqiang

2014-01-01

130

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

NASA Astrophysics Data System (ADS)

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

Guo, Lidan; Xia, Ziqiang

2013-04-01

131

Temperature Trends at the South Pole and McMurdo Sound  

Microsoft Academic Search

A detailed analysis of atmospheric temperatures at the South Pole and McMurdo Sound is presented. Missing data are common, especially in the stratosphere, and the usual practice of computing monthly means as an average of all available observations produces unreliable results because the annual cycle is aliased onto the interannual variations and longer term trends. A methodology to rectify this

Kevin E. Trenberth; Jerry G. Olson

1989-01-01

132

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

133

Trends in Antarctic Surface Temperatures and Ice Extent from Satellite and Surface Observations  

NASA Technical Reports Server (NTRS)

Surface air temperatures observed from stations around Antarctica have indicated predominantly positive trends which are as high as 0.4K per decade along the Antarctic Peninsula. Since the average air temperature during summer in the West Antarctic region is about -6 K, and since most of the stations are near coastal regions, it is important to know whether such trends are due to a local or large scale phenomenon. We analyzed about 19 years of infrared satellite data (1979-1997) to obtain a spatially detailed study of the variability of surface temperatures over the entire Antarctic region. We also analyzed potential impact of temperature changes over the sea ice cover using co-registered and nearly coincident microwave satellite data. The surface temperatures inferred from infrared data are shown to agree well with those observed from the limited number of Antarctic station data with a correlation coefficient of 0.98 and a standard deviation of less than 3K. The 19-year temperature data set shows positive trends of 0.12, 0.68, and 0.41 C per decade in ocean, sea ice and ice sheet surfaces, respectively. The sensitivity of the trend to record length was studied, using long term station data sets, and the results show that the trends start to stabilize at around 2 decades which is about the record length of satellite data. However, interannual fluctuations of the temperatures are large, especially in the ice sheets, and the 95% confidence level for the trends ranges from 0.12 to 1.22 for sea ice and from -0.74 to 1.55 C per decade for the ice sheet. In the sea ice regions, the position of the ice edge in winter with respect to the northernmost position of sea ice during the study period is also shown to be influenced by alternating warm and cold anomalies around the continent. This pattern is similar to that suggested by the presence of the Antarctic Circumpolar Wave (ACW) but the wavenumber appears to be predominantly mode 3 (instead of reported mode 2) for the Antarctic region. Unexpectedly, trends in the sea ice extent are found to be positive in most Antarctic sectors during the same period with the exception of the Bellingshausen and Amundsen Seas region.

Comisc, J. C.

1998-01-01

134

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

135

Analysis of Linear and Nonlinear Sea Level Trends in the North Atlantic  

NASA Astrophysics Data System (ADS)

Since the sea surface changes in response to many forcings occurring at different time scales, analysis of the interactions between the different scales of variation is important to understanding how sea level has varied in the past and how it will vary in the future. Geographically uneven sea level trends (SLT) in the North Atlantic were analyzed using the monthly mean altimetry sea surface height anomaly (SSHA) from January 1993 to December 2011. In order to understand the different time scales in SSHA variability, the data were decomposed into seasonal, annual, interannual, decadal and residual signals using Ensemble Empirical Mode Decomposition (EEMD). Using the EEMD residual the nonlinear SLT was determined, which shows the turning point of the SLT during either the rising or falling trend. While a downswinging inflection was the dominant pattern in the regions of sea level rise occurring after 2007 in the Subpolar Gyre, the Subtropical Gyre, and the Equatorial Current, a pattern of upswinging inflection was dominated in the regions where sea level was significantly decreasing after about 2000 close to the North Atlantic Current and Northern Recirculation Gyre. We may therefore understand whether sea level changes in different regions are in phase or out of phase, and with how much lag.

Jo, Y.; Yan, X.

2013-05-01

136

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

137

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

138

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

139

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

140

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

141

Interannual Trends in Southern Ocean Sea Surface Temperatures and Sea Level from Remote Sensing Data  

NASA Astrophysics Data System (ADS)

As is shown in last years researches climate changes in Antarctic result in interannual increase trend of surface air temperature and decrease of ice thickness These tendencies are must try in the Southern Ocean hydrological regime For that next remote sensing data AVHRR MCSST data and satellite altimetry data merged data of mission ERS TOPEX Poseidon Jason-1 ENVISAT GFO-1 are used to this task which give information about sea surface temperature SST and sea level anomaly SLA correspondingly According to obtained results SST has positive trend more 0 01 oC yr for 23-yr record 1982-2005 within 300-1000 km northward Antarctic coast However on average for the Southern Ocean SST have negative trend about -0 018 -0 035 oC yr In area of Pacific-Antarctic Ridge and of southern part of Mid Atlantic Ridge decrease rate is more than -0 075 oC yr SLA increases in all area of the Southern Ocean and has average rate about 0 024 -0 026 cm yr for 12-yr record 1993-2005 Around Antarctic SST rate good correspond with the trend analysis of surface air temperature of 8722 0 042 - 0 067oC yr inferred from the satellite 20-yr record Comiso 2000 Nevertheless the observed cooling is intriguing especially since it is compatible with the observed trend in the sea ice cover In the sea ice regions the northernmost positions of the ice edge are shown to be influenced by alternating warm and cold anomalies around the continent This work was partly supported by the Russian Fund of Basic Research Grant 06-05-65061

Lebedev, S. A.

142

Are there evidences of altitudinal effects of air temperature trends in the European Alps 1820-2013?  

NASA Astrophysics Data System (ADS)

We use the HISTALP data set (www.zamg.ac.at/histalp) in order to assess the elevation dependency of air temperature trends within the European Alps. The evidence of altitudinal effects of the climate warming (with higher sensitivity of high mountain regions to warming) is a key statement, or at least key hypothesis, in many studies. The high relevance of such statement resp. hypothesis is obvious if one consider the impacts resulting from such fact, such as snow- and glacier melting and related effects for mountain hydrology. The HISTALP data set stands out with respect to its series lengths and its high level of homogenisation. Interestingly, the HISTALP temperature data show no clear altitudinal dependency of warming or cooling trends within the period 1820-2013. Additionally, a rather homogenous temporal trend could be observed within the entire Greater Alpine Region (GAR). Because HISTALP include also air pressure and vapour pressure series, we could compare our measured air temperatures with mean-column air temperatures, computed by the barometric formula, which were derived from the independently measured air pressure data (using vapour pressure to account for the atmospheric water content) at low resp. high elevations. Computed mean column temperatures are in good agreement with observed temperatures, indicating generally homogenous temporal temperature trend behaviour at different elevations. Our finding contradicts several results from climate modelling attempts and also other studies investigating Alpine temperature trends. We conclude that, whereas modelling results are still limited in the assessment of altitudinal effect of temperature trends from missing atmospheric processes captured by the models, the difference of the trend behaviour compared to other analyses of instrumental air temperatures comes from the seasonal base taken as the basis for trend estimation. It appears that opposite trend in spring and autumn for the period 1980-2000, respectively, levels each other out for the annual temperature trend.

Schoener, W.; Auer, I.; Chimani, B.; Garnekind, M.; Haslinger, K.

2013-12-01

143

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

NASA Astrophysics Data System (ADS)

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

Tang, Guoping; Arnone, John A.

2013-05-01

144

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

145

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

146

Trends in the design of spectroscopy amplifiers for room temperature solid State detectors  

Microsoft Academic Search

This 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

Pier Francesco Manfredi; Valerio Re

2004-01-01

147

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

148

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

149

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

150

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

2013-11-01

151

Trend detection in surface air temperature in Ontario and Quebec, Canada during 1967-2006 using the discrete wavelet transform  

NASA Astrophysics Data System (ADS)

The main purpose of this study is to detect trends in the mean surface air temperature over the southern parts of Ontario and Quebec, Canada, for the period of 1967-2006. This is accomplished by determining the most dominant periodic components that affect trends in different temperature data categories (monthly, seasonally-based, seasonal, and annual), which were obtained from a total of five stations. The discrete wavelet transform (DWT) technique, the Mann-Kendall (MK) trend test, and sequential Mann-Kendall analysis were used in this study — co-utilizing these techniques in temperature trend studies has not been explored extensively. The mother wavelet, number of decomposition levels, and boundary condition were determined using a newly proposed criterion based on the relative error of the MK Z-values between the original data and the approximation component of the last decomposition level. This study found that all stations experienced positive trends: significant trends were observed in all of the monthly, seasonally-based, and annual data. For the different seasons, although the trend values were all positive, not all stations experienced significant trends. It was found that high-frequency components ranging from 2 to 12 months were more prominent for trends in the higher resolution data (i.e. monthly and seasonally based). The positive trends observed for the annual data are thought to be mostly attributable to warming during winter and summer seasons, which are manifested in the form of multiyear to decadal events (mostly between 8 and 16 years).

Nalley, D.; Adamowski, J.; Khalil, B.; Ozga-Zielinski, B.

2013-10-01

152

Evaluation of notched fatigue strength at elevated temperature by linear notch mechanics  

Microsoft Academic Search

The notched fatigue strength of nickel-base superalloy Inconel 718 has been investigated under rotating bending loading at room temperature and 500°C in air. The applicability of linear notch mechanics to the evaluation of notched fatigue strength at elevated temperature was assessed in terms of the fatigue limit for crack initiation and that for crack growth. The effect of temperature on

Qiang Chen; Norio Kawagoishi; Hironobu Nisitani

1999-01-01

153

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

NASA Astrophysics Data System (ADS)

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

Bian, Qiying; Lu, Riyu

2013-04-01

154

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.

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

2013-01-01

155

Low temperature exponential and linear free decay of third sound resonances  

NASA Astrophysics Data System (ADS)

Low temperature free decays of third sound resonances show weak exponential attenuation at low amplitudes. A variety of behaviors has been observed at high amplitudes including stronger exponential decays and occasional linear decays. The flow velocities characteristic of the onset of these non linear effects are typically 1cm/s. Pinned vortices appear to play a major role in the damping.

Ellis, F. M.; Luo, H.

1991-02-01

156

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

157

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

158

Non-linear Dielectric Responses of a Model Glass Former under Oscillating Temperature  

NASA Astrophysics Data System (ADS)

Exploiting a simple model for glass formers, we investigate dielectric response under oscillating temperature. We find that three characteristic temperatures, Vogel--Fulcher, glass transition and cross-over temperatures, can be determined from the analysis of the non-linear dielectric response. We also find a new characteristic temperature T3 which signifies divergence of the third moment of the waiting time distribution and can be detected by additional peaks in the imaginary part of the second order susceptibility.

Odagaki, Takashi; Kuroda, Masatoshi; Saruyama, Yasuo

2012-10-01

159

Historical trends in tank 241-SY-101 waste temperatures and levels  

SciTech Connect

The gas release and fluctuating level of the waste in tank 241-SY-101 have prompted more detailed interest in its historical behavior, in hopes of achieving a better understanding of its current status. To examine the historical behavior, essentially all of the tank waste temperature and level data record has been retrieved, examined, and plotted in various ways. To aid in interpreting the data, the depth of the non-convective waste layer was estimated by using a least-squares Chebyshev approximation to the temperatures. This report documents the retrieval critical examination, and graphic presentation of 241-SY-101 temperature and waste level histories. The graphic presentations clearly indicate a tank cooling trend that has become precipitous since late 1991. The plots also clearly show the decreasing frequency of waste gas release events, increasing height of the non-convective layer, and larger level drops per event.

Antoniak, Z.I.

1993-09-01

160

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

161

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

162

Evaluation of a Linear Mixing Model to Retrieve Soil and Vegetation Temperatures of Land Targets  

NASA Astrophysics Data System (ADS)

A simple linear mixing model of heterogeneous soil-vegetation system and retrieval of component temperatures from directional remote sensing measurements by inverting this model is evaluated in this paper using observations by a thermal camera. The thermal camera was used to obtain multi-angular TIR (Thermal Infra-Red) images over vegetable and orchard canopies. A whole thermal camera image was treated as a pixel of a satellite image to evaluate the model with the two-component system, i.e. soil and vegetation. The evaluation included two parts: evaluation of the linear mixing model and evaluation of the inversion of the model to retrieve component temperatures. For evaluation of the linear mixing model, the RMSE is 0.2 K between the observed and modelled brightness temperatures, which indicates that the linear mixing model works well under most conditions. For evaluation of the model inversion, the RMSE between the model retrieved and the observed vegetation temperatures is 1.6K, correspondingly, the RMSE between the observed and retrieved soil temperatures is 2.0K. According to the evaluation of the sensitivity of retrieved component temperatures on fractional cover, the linear mixing model gives more accurate retrieval accuracies for both soil and vegetation temperatures under intermediate fractional cover conditions.

Yang, Jinxin; Jia, Li; Cui, Yaokui; Zhou, Jie; Menenti, Massimo

2014-03-01

163

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

164

UNCERTAINTIES IN CLIMATE TRENDS: Lessons from Upper-Air Temperature Records.  

NASA Astrophysics Data System (ADS)

Historically, meteorological observations have been made for operational forecasting rather than long-term monitoring purposes, so that there have been numerous changes in instrumentation and procedures. Hence to create climate quality datasets requires the identification, estimation, and removal of many nonclimatic biases from the historical data. Construction of a number of new tropospheric temperature climate datasets has highlighted previously unrecognized uncertainty in multidecadal temperature trends aloft. The choice of dataset can even change the sign of upper-air trends relative to those reported at the surface. So structural uncertainty introduced unintentionally through dataset construction choices is important and needs to be understood and mitigated. A number of ways that this could be addressed for historical records are discussed, as is the question of How it needs to be reduced through future coordinated observing systems with long-term monitoring as a driver, enabling explicit calculation, and removal of nonclimatic biases. Although upper-air temperature records are used to illustrate the arguments, it is strongly believed that the findings are applicable to all long-term climate datasets and variables. A full characterization of observational uncertainty is as vitally important as recent intensive efforts to understand climate model uncertainties if the goal to rigorously reduce the uncertainty regarding both past and future climate changes is to be achieved.

Thorne, Peter W.; Parker, David E.; Christy, John R.; Mears, Carl A.

2005-10-01

165

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

166

[Research on granary temperature network monitoring system based on the linear frequency shift of spectrum].  

PubMed

In order to obtain the distribution of the temperature in the range of the granary precisely and stably, we designed a temperature measurement system of the fiber Bragg grating. Through the fiber-optic network the system can detect granary temperature in a wide range, and there is a linear relationship between the measured temperature by fiber Bragg grating and the center wavelength, so according to the function of spectrum linear frequency shift it obtained precise temperature in the granary. The working wavelengths of each grating in the system are separated from each other. After reflected by 3 dB coupler, the wavelength detection and demodulation system was used to measure the linear frequency shift of the plurality grating, and the system can get temperature data of everywhere in the granary. The experimental obtained the temperature information by equipments, such as LPT-101 light source, optical fiber with FBG encapsulated, magnification processing circuit, simulation granary, etc. With Origin software the diagram of the relationship between the frequency shift of the measured temperature and wavelength was drawn, and compared with the traditional measuring method of the K-type thermocouple measurement data. Experimental results show that the measured temperature of the fiber Bragg grating is closer to standard temperature, and the anti-jamming ability can meet the requirements of the granary large range temperature monitoring. PMID:23841446

Wang, Gao; Liu, Shao-Cong; Wen, Qiang; Zhao, Hui; Zhao, Yu

2013-04-01

167

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

168

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

169

Linear temperature dependence of susceptibility of UAl/sub 2/ between 3 and 10 K  

SciTech Connect

A linear variation of magnetic susceptibility versus temperature is observed for UAl/sub 2/ for 3 K< or =T< or =10 K and for applied fields of 0.1, 1, 2, and 5 T. Although a quadratic dependence is not observed within this temperature range, the results are consistent with specific-heat measurements.

Foner, S.; Stewart, G.R.; Giorgi, A.L.

1985-10-01

170

Combined Use of Multiple Linear Regression, Optimal Interpolation and Gis In Producing Temperature Maps  

Microsoft Academic Search

In intention to produce climate maps of monthly and annual average air temperature for the CLINO period 1961-1990 the data from the meteorological stations are inter- polated to regular grid. Combined use of multiple linear regression method and opti- mal interpolation was introduced. For every grid point, the temperature anomaly from the corresponding average is assumed in the form of

M. Percec Tadic; K. Pandzic

2002-01-01

171

Multi-decadal surface temperature trends in the East Antarctica using borehole firn temperature measurements and geophysical inverse method  

NASA Astrophysics Data System (ADS)

The interior of East Antarctic Ice Sheet (EAIS) remains one of the least explored areas on earth and as a result, its climate is one of the least-understood as well. Recent studies with techniques utilizing sparse available records and models have estimated a weak warming trend in East Antarctica for the past 50 years. However, these are not without uncertainties and additional data sources are needed in order to gain a better assessment of the East Antarctic climate trend. The objective of this investigation is to detect multi-decadal surface temperature trends in the interior of East Antarctica. Surface temperature inversion from vertical firn temperature profile measurements at several locations provides a source of climate reconstruction independent of firn chemistry, sparse weather data, satellite data, or ice cores. During the Norwegian-U.S. IPY Scientific Traverse of East Antarctica, in austral summers of 2007-08 and 2008-09, thermal-profiling units were installed at five locations. Each unit consists of 16 PRTs (Platinum Resistance Thermometers) distributed between depths of 0.15 and approximately 90 m. Wired PRTs were lowered into the borehole after an ice core was drilled and before the hole was back-filled with granulated snow to prevent air circulation and provide thermal conduction between PRTs and firn. Near-hourly data are being transmitted through ARGOS satellite telemetry system. The overall uncertainty in firn temperature measurement is 0.03 °C. A geophysical inverse method using the generalized inverse and regularization method was applied to one full year of data collected from three units installed in 2007-08. Results indicate that the recent decade is approximately 0.5 to 0.8 °C warmer than ~100 years ago, given assumptions on physical characteristics of the ice sheet (accumulation rate, geothermal heat flux, vertical advection, density and thermal properties). However, the precise onset and rate of the warming are undetermined at this stage. We will also present the preliminary results from the two sites installed in 2008-09 season, as well as the use of Monte Carlo inverse method. Initial analysis suggests that the southern station supports the results of the earlier stations but the near-coastal station near Kohnen appears to indicate a more significant warming.

Muto, A.; Scambos, T.; Steffen, K.

2009-12-01

172

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

173

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

174

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

175

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

176

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

177

Amplification of Surface Temperature Trends and Variability in the Tropical Atmosphere  

NASA Astrophysics Data System (ADS)

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

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

2005-09-01

178

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

179

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

NASA Astrophysics Data System (ADS)

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

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

2011-11-01

180

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

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

181

The effects of ionizing radiation on the Honeywell HTMOS high temperature linear CMOS technology  

Microsoft Academic Search

The high dose-rate transient response and radiation hardness to total ionizing dose of Honeywell's HTMOS 10 V linear technology were evaluated. Although this technology was designed for high-temperature applications, all irradiation and measurements herein were performed at room temperature. Results show that the HT1104 Quad Operational Amplifier and HT1204 Quad Analog Switch survive 5×1011 rads(Si)\\/s, with recovery times ⩽10 ?s.

D. Larsen; P. Welling; W. Tsacoyeanes

1996-01-01

182

Filter Radiometers as a Tool for Quality Assurance of Temperature Measurements with Linear Pyrometers  

Microsoft Academic Search

Measurements made with a pyrometer are vulnerable to errors if the pyrometer is misaligned, inaccurately characterized, or\\u000a malfunctioning. In this work, thermodynamic temperatures between 1,373 and 1,773 K were studied by measuring a variable-temperature\\u000a blackbody with a linear pyrometer and four absolutely characterized filter radiometers. The filter radiometer measurements\\u000a were done in the irradiance mode. In the first set of measurements,

M. Ojanen; V. Ahtee; M. Noorma; T. Weckström; P. Kärhä; E. Ikonen

2008-01-01

183

Effect of temperature on tribological performance of a silicon nitride ball material with a linear perfluoropolyalkylether  

Microsoft Academic Search

The effect of temperature in rolling contact performance of a hot isostatically pressed (HIP) silicon nitride ball material with a linear perfluoropolyalkylether (PFPAE) was studied using a ball-on-rod type rolling contact fatigue tester. The test temperature ranged from ambient to 343?°C for a period of 24 h at a stress of 5.5 GPa using thin dense chrome (TDC)-coated T-15 bearing

H. K. Trivedi; C. S. Saba

2001-01-01

184

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

185

A contribution to the linear low temperature specific heat of dilute alloys arising from superparamagnetic clusters  

Microsoft Academic Search

Low temperature specific heat measurements on a copper +0.7 at% cobalt alloy isothermally aged at 400 degrees C indicate the existence of a linear magnetic cluster specific heat contribution as predicted by the theory of superparamagnetism. Quantitative analysis of the contribution making use of particle size data from magnetic measurements gives a mean anisotropy energy of order 106 erg cm-3.

E. J. Hayes; A. Hahn; E. P. Wohlfarth

1972-01-01

186

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

187

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

188

Kinetic analysis of thermogravimetric data obtained under linear temperature programming—a method based on calculations of the temperature integral by interpolation  

Microsoft Academic Search

A new technique, called interpolation method, with general application in the kinetic analysis of processes studied by thermogravimetry (TG) under linear temperature programming is developed. It is based on the linear relationship, with slope 1, between logg(?) and logI(?, ?) for the appropriate kinetic function, where I(?, ?) is the normalized temperature integral, ? the normalized temperature (?=T\\/T0) and ?

J. J. M Órfão; F. G Martins

2002-01-01

189

Temperature dependence and temporal trends of polychlorinated biphenyl congeners in the Great Lakes atmosphere  

SciTech Connect

As part of the Integrated Atmospheric Deposition Network (IADN), the authors have measured gas-phase polychlorinated biphenyl (PCB) concentrations in the atmosphere around the Great Lakes since November of 1990. In this paper, they use these data to explore the temperature and time dependencies of gas-phase PCB concentrations near Lakes Superior, Michigan, and Erie and in Chicago. Concentrations of individual PCB congeners were well correlated to temperature for the three remote sites using the Clausius-Clapeyron equation, but the calculated heats of surface-air exchange did not correlate (on a congener basis) with laboratory-measured heats of vaporization. On the other hand, the heats of surface-air exchange for PCB congeners measured in Chicago are well correlated with laboratory-measured heats of vaporization. The authors conclude that the gas-phase PCB concentrations measured at Chicago are controlled by short-range transport, but at the three remote sites, these concentrations are controlled by long-range transport. Gas-phase PCBs also exhibited decreasing concentrations over the period 1991--1997 near Lakes Michigan and Erie and in Chicago. Significant half-lives ranged from 0.5 to 7.5 years for individual congeners and 2.8 to 3.3 years for total PCBs. Gas-phase PCBs near Lake Superior showed no general trend in gas-phase concentration over this same time period.

Simcik, M.F.; Basu, I.; Hites, R.A. (Indiana Univ., Bloomington, IN (United States)); Sweet, C.W. (Illinois State Water Survey, Champaign, IL (United States))

1999-06-15

190

Linear temperature dependence of the electron dephasing scattering rate in disordered thick Sc films  

SciTech Connect

We have extracted the temperature dependence of the electron dephasing scattering time {tau}{sub {phi}}(T) from a three-dimensional weak-localization study of disordered thick Sc films. We find that {tau}{sub {phi}} varies with the inverse of temperature, i.e., {tau}{sub {phi}}{approximately}T{sup {minus}1}, over the wide temperature range 0.3{endash}10 K. This linear T dependence of {tau}{sub {phi}}{sup {minus}1} is understood in terms of the current theoretical concept for electron-electron scattering in strongly disordered bulk metals. {copyright} {ital 1997} {ital The American Physical Society}

Li, T.; Lin, J.J. [Department of Physics, National Taiwan University, Taipei 106 (Taiwan)] [Department of Physics, National Taiwan University, Taipei 106 (Taiwan)

1997-10-01

191

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

192

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

193

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

194

Finite difference modelling of the temperature rise in non-linear medical ultrasound fields.  

PubMed

Non-linear propagation of ultrasound can lead to increased heat generation in medical diagnostic imaging due to the preferential absorption of harmonics of the original frequency. A numerical model has been developed and tested that is capable of predicting the temperature rise due to a high amplitude ultrasound field. The acoustic field is modelled using a numerical solution to the Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation, known as the Bergen Code, which is implemented in cylindrical symmetric form. A finite difference representation of the thermal equations is used to calculate the resulting temperature rises. The model allows for the inclusion of a number of layers of tissue with different acoustic and thermal properties and accounts for the effects of non-linear propagation, direct heating by the transducer, thermal diffusion and perfusion in different tissues. The effect of temperature-dependent skin perfusion and variation in background temperature between the skin and deeper layers of the body are included. The model has been tested against analytic solutions for simple configurations and then used to estimate temperature rises in realistic obstetric situations. A pulsed 3 MHz transducer operating with an average acoustic power of 200 mW leads to a maximum steady state temperature rise inside the foetus of 1.25 degrees C compared with a 0.6 degree C rise for the same transmitted power under linear propagation conditions. The largest temperature rise occurs at the skin surface, with the temperature rise at the foetus limited to less than 2 degrees C for the range of conditions considered. PMID:10829673

Divall, S A; Humphrey, V F

2000-03-01

195

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

196

Long term trend of sea surface temperature in the South China Sea  

NASA Astrophysics Data System (ADS)

Using HAdISST the long term trend in the South China Sea (SCS) sea surface temperature (SST) between 1950 and 2008 is investigated. In general SST has been increased since 1950, but the rate of increase is spatiotemporally uneven. Winter warming rate is greater than that of summer. In both seasons the rate of increase is greater during 1980s. Winter warming rate is greater over the deeper basin while summer warming rate is greater over the shallower southeastern part. In summer the weakening of southwesterly monsoon reduces upwelling along the east coast of Vietnam to warm the surface. On the other hand, the net surface heat flux, however, is reduced and cannot contribute to the warming. In winter the net heat flux into the sea increases and could contribute to the warming. The spatial pattern of the heat flux, however, is different from that of the warming. The heat flux is increased over the coastal area where warming is small, but decreased in deeper part where warming is greater. After 1980's the northeasterly monsoon winds weakens to reduce the southward western boundary currents, and subsequently cold advection and to warm the area.

Choi, A.; Park, Y.

2012-12-01

197

Occurrence, temperature and seasonal trends of ?- and ?-HCH in air (Québec, Canada)  

NASA Astrophysics Data System (ADS)

Atmospheric concentrations of ?- and ?-hexachlorocyclohexane (HCH) were measured during 1993-1995 along the St. Lawrence River in Québec, Canada. Average ?- and ?-HCH concentrations (pg/m 3) were St. Anicet: 93-101; Villeroy: 92-42; Mingan: 96-20, respectively. ?-HCH mean concentrations were similar in all sites and appeared to be more influenced by long-range transport than local sources. ?-HCH mean levels in St. Anicet were 2 and 5 times higher than in Villeroy and Mingan, respectively. The time-series of ?-HCH air concentrations at St. Anicet and Villeroy were characterised by highly elevated springtime episodes, which are in agreement with the ?-HCH usage in Québec as corn seed dressing pesticide. No temporal trend was observed for the ?-HCH in air. Clausius-Clapeyron plots (log conc. vs. 1/ T) showed a stronger correlation between temperature and measured ?-HCH concentrations at St. Anicet and Villeroy than Mingan. On a regional scale, the influence of the local sources of ?-HCH implied a seasonal variability in air concentrations due to its short transport, while at the background site (Mingan), the observed ?- and ?-HCH concentrations in air were the result of its long-range transport and/or water/air gas exchanges.

Garmouma, Mourad; Poissant, Laurier

198

A High Dynamic Range 100Mhz AGC-Amplifier with a Linear and Temperature Compensated Gain Control  

Microsoft Academic Search

In this paper the control voltage related temperature dependencies of a current deviation based AGC amplifier are studied. A control circuit with linear and temperature compensating gain control is presented

H. Riihihuhta; Kari Halonen; Kari Koli

1994-01-01

199

Three modes of interdecadal trends in sea surface temperature and sea surface height  

NASA Astrophysics Data System (ADS)

It might be thought that sea surface height and sea surface temperature would be tightly related. We show that this is not necessarily the case on a global scale. We analysed this relationship in a suite of coupled climate models run under 1860 forcing conditions. The models are low-resolution variants of the GFDL Earth System Model, reported in Galbraith et al. (J. Clim. 2011). 1. Correlated changes in global sea surface height and global sea surface temperature. This mode corresponds to opening and closing of convective chimneys in the Southern Ocean. As the Southern Ocean destratifies, sea ice formation is suppressed during the winter and more heat is taken up during the summer. This mode of variability is highly correlated with changes in the top of the atmosphere radiative budget and weakly correlated with changes in the deep ocean circulation. 2. Uncorrelated changes in global sea surface height and global sea surface temperature. This mode of variability is associated with interdecadal variabliity in tropical winds. Changes in the advective flux of heat to the surface ocean play a critical role in driving these changes, which also result in significant local changes in sea level. Changes sea ice over the Southern Ocean still result in changes in solar absorption, but these are now largely cancelled by changes in outgoing longwave radiation. 3. Anticorrelated changes in global sea surface height and global sea surface temperatures. By varying the lateral diffusion coefficient in the ocean model, we are able to enhance and suppress convection in the Southern and Northern Pacific Oceans. Increasing the lateral diffusion coefficients shifts the balance sources of deep water away from the warm salty deep water of the North Atlantic and towards cold fresh deep water from the other two regions. As a result, even though the planet as a whole warms, the deep ocean cools and sea level falls, with changes of order 30 cm over 500 years. The increase in solar absorption in polar regions is more than compensated by an increase in outgoing longwave radiation. Relationship between global SSH trend over a decade and (A) local SSH change over a decade (m/m). (B) Global SST change over a decade (m/K) (C) Portion of decadal SST change correlated with net radiation at the top of the atmosphere (m/K) (D) Portion of decadal SST change not correlated with net radiation at the top of the atmosphere.

Gnanadesikan, A.; Pradal, M.

2013-12-01

200

How well does the ERA-Interim reanalysis replicate trends in extremes of surface temperature across Europe?  

NASA Astrophysics Data System (ADS)

Trends in extremes of daily maximum and minimum temperature across Europe derived from the European Centre for Medium-Range Weather Forecasts ERA-Interim reanalysis are compared against observed data. The period 1980-2011 is considered and both station series and the gridded E-OBS data are used to determine the success of the reanalysis, with indices of the numbers of days above or respectively below the 90th and 10th percentiles of daily maximum and minimum temperature used as metrics. It is shown in this paper that the ERA-Interim reanalysis data are generally very good at replicating both the seasonally and spatially varying trends in the indices across Europe. At the station level, the reanalysis data are also able to depict the observed trends remarkably well. However, the success of the reanalysis data depends on the season and the particular index considered. The reanalysis is least successful in replicating trends in the number of days exceeding the 90th percentile of maximum temperature, particularly during the summer season. The success of the reanalysis is also somewhat dependent on the time step of the reanalysis data used. Daily maximum and minimum temperatures calculated from the 3-hourly time step reanalysis data tend to be more reliable than those derived from the 12-hourly data.

Cornes, R. C.; Jones, P. D.

2013-09-01

201

Temperature Trends of the U.S. Historical Climatology Network Based on Satellite-Designated Land Use\\/Land Cover  

Microsoft Academic Search

The 1221 weather observation stations that compose the U.S. Historical Climatology Network were designated as either urban, suburban, or rural based on data from the Defense Meteorological Satellite Program Operational Linescan System (OLS). The designations were based on local and regional samples of the OLS data around the stations (OLS method). Trends in monthly maximum and minimum temperature and the

Kevin P. Gallo; Timothy W. Owen; David R. Easterling; Paul F. Jamason

1999-01-01

202

Temperature Trends of the U.S. Historical Climatology Network Based on Satellite-Designated Land Use\\/Land Cover  

Microsoft Academic Search

The 1221 weather observation stations that compose the U.S. Historical Climatology Network were designated as either urban, suburban, or rural based on data from the Defense Meteorological Satellite Program Operational Linescan System (OLS). The designations were based on local and regional samples of the OLS data around the stations (OLS method). Trends in monthly maximum and minimum temperature and the

KEVIN P. G ALLO; TIMOTHY W. O WEN; DAVID R. EASTERLING; PAUL F. J AMASON

203

Methodology and Results of Calculating Central California Surface Temperature Trends: Evidence of Human-Induced Climate Change?  

Microsoft Academic Search

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

John R. Christy; William B. Norris; Kelly Redmond; Kevin P. Gallo

2006-01-01

204

Climatology and trends of mesospheric (58-90) temperatures based upon 1982-1986 SME limb scattering profiles  

NASA Technical Reports Server (NTRS)

Atmospheric temperature profiles for the altitude range 58-90 km were calculated using data on global UV limb radiances from the SME satellite. The major elements of this climatology include a high vertical resolution (about 4 km) and the coverage of the 70-90 km altitude region. The analysis of this extensive data set provides a global definition of mesospheric-lower thermospheric temperature trends over the 1982-1986 period. The observations suggest a pattern of 1-2 K/year decreases in temperatures at 80-90-km altitudes accompanied by 0.5-1.5 K/year increases in temperatures at 65-80-km altitudes.

Clancy, R. Todd; Rusch, David W.

1989-01-01

205

A Cascade Linear Filter to Reduce Revisions and False Turning Points for Real Time Trend-Cycle Estimation  

Microsoft Academic Search

The problem of identifying the direction of the short-term trend (nonstationary mean) of seasonally adjusted series contaminated by high levels of variability has become of relevant interest in recent years. In fact, major financial and economic changes of global character have introduced a large amount of noise in time series data, particularly, in socioeconomic indicators used for real time economic

Estela Bee Dagum; Alessandra Luati

2008-01-01

206

Temperature-dependent non-linear rheological models of plate spreading in Iceland  

NASA Astrophysics Data System (ADS)

The Mid-Atlantic Ridge system is exposed above sea level in Iceland, which provides a natural laboratory to study plate spreading and corresponding surface deformation. Extensive GPS geodetic measurements reveal the style of extension in Iceland. Such observations have been fit to kinematic models with an opening dislocation in an elastic halfspace or stretching elastic-viscoelastic modeling. Most of these models use either elastic rheology or a rheology where relation between stress and strain is linear. However, in reality Earth's rheology may be non-linear and strongly temperature dependent. Here we aim to fit plate spreading models considering these effects to observed style of spreading in Iceland. For this purpose we have carried out finite element modeling considering temperature-dependent non-linear rheology. Two-dimensional symmetric thermo-mechanical coupling models are performed where rheology follows dislocation creep considering a subsurface temperature. The models stretch as to reproduce plate spreading. The rheology in the model corresponds to that of olivine as it is the major mineral in the upper mantle and, laboratory experiment of olivine and numerical modeling are similar. We consider both to so called wet and dry olivine rheology. Temperature distribution in models take into account thermal studies in Iceland. We apply high temperature (700 °C) at varies depth (1-15 km for Eastern and 1-10 km for Northern Volcanic Zones). We also perform kinematic elastic dislocation dike opening models to compare temperature dependent rheology models. Wet and dry mantle rheology models give more or less similar results compare to two profiles. Horizontal displacements predicted by the models are compared to observed horizontal displacements from GPS observations along two profiles in the Northern and Eastern Volcanic Zones of Iceland. The best fit temperature-dependent rheology models, minimizing residuals between observations and model predictions provide an estimate for depth to 700 °C temperature. It is 11-13 and 5-6 km for Eastern and Northern Volcanic Zones, respectively. Beneath the Northern Volcanic Zone the suggested average temperature gradient is ~140 °C/km whereas it is relatively cooler for Eastern Volcanic Zone as temperature gradient is ~60 °C/km at the rift axis.

Tariqul Islam, Md.; Sturkell, Erik; Sigmundsson, Freysteinn; Ófeigsson, Benedikt G.

2013-04-01

207

Linear viscoelastic limits of asphalt concrete at low and intermediate temperatures  

NASA Astrophysics Data System (ADS)

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

Mehta, Yusuf A.

208

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

209

Two aspects of the Simplex Model: goodness of Fit to Linear Growth Curve Structures and the Analysis of Mean Trends  

Microsoft Academic Search

Considers the analysis of longitudinal data by means of the autogressive or simplex model. The finding by D. Rogosa and J. B. Willett that the quasi-Markov simplex model fits a linear growth curve covariance structure is investigated. Under various circumstances the quasi-Markov simplex model is rejected. The procedure is reversed by fitting the linear growth curve to quasi-Markov simplex covariance

P. C. M. Molenaar; Conor V. Dolan; F. Mandys

1994-01-01

210

An empirical technique for estimating near-surface air temperature trends in central Greenland from SSM\\/I brightness temperatures  

Microsoft Academic Search

In central Greenland, near-surface air temperatures can be estimated from long-term satellite passive microwave brightness temperatures supported by limited air-temperature data from automatic weather stations. In this region, brightness temperature depends on snow emissivity, which varies slowly over time, and on snow temperature, which varies more rapidly and is controlled by air temperature. The air temperature and brightness temperature data

C. A. Shuman; R. B. Alley; S. Anandakrishnan; C. R. Stearns

1995-01-01

211

The design and construction of a high temperature linear electromagnetic actuator  

NASA Astrophysics Data System (ADS)

This article is concerned with the design and construction of a bidirectional linear actuator capable of operating in ambient temperatures of up to 800 °C with a rated force of 300 N and a stroke of +/-0.5 mm. The electromagnetic design synthesis strategy employed is described with particular emphasis on those aspects most markedly affected by the high operating temperature, viz. the selection of an appropriate actuator topology and the relative merits of candidate soft magnetic alloys. The key role of detailed thermal modeling, particularly the importance of radiation as a heat transfer mechanism in such high temperature applications, is illustrated during the design synthesis. The construction of a prototype actuator is discussed, including the use of tape would conductors with ceramic insulation and Inconel 600 disk springs as bearing elements.

Sidell, N.; Jewell, G. W.

1999-04-01

212

Room-temperature single photon sources with definite circular and linear polarizations  

NASA Astrophysics Data System (ADS)

We report experimental results of two room-temperature single photon sources with definite polarization based on emitters embedded in either cholesteric or nematic liquid crystal hosts. In the first case, a cholesteric 1-D photonic bandgap microcavity provides circular polarization of definite handedness of single photons from single colloidal semiconductor quantum dots (nanocrystals). In these experiments, the spectral position of the quantum dot fluorescence maximum is at the bandedge of a photonic bandgap structure. The host does not destroy fluorescence antibunching of single emitters. In the second case, photons with definite linear polarization are obtained from single dye molecules doped in a planar-aligned nematic liquid crystal host. The combination of sources with definite linear and circular polarization states of single photons can be used in a practical implementation of the BB84 quantum key distribution protocol.

Lukishova, S. G.; Bissell, L. J.; Stroud, C. R.; Boyd, R. W.

2010-03-01

213

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

214

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

215

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

216

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

217

Day-of-the-week variations of urban temperature and their long-term trends in Japan  

NASA Astrophysics Data System (ADS)

Temperature differences among days of the week and their long-term trends were evaluated using 29 years of hourly data from the Automated Meteorological Data Acquisition System network of Japan. Stations were categorized with respect to the population density around each site, and an urban temperature anomaly ( ?T*) was defined as a departure from the spatial average of nearby rural stations. On Saturdays and holidays (Sundays and national holidays), ?T* was lower than on weekdays by 0.2-0.25°C at Tokyo, by 0.1-0.2°C at Osaka, and by about 0.02°C at stations where the population density was 300 to 1,000 km-2. Moreover, ?T* showed a relative decreasing trend over the long term on Mondays and an increasing trend on Fridays, at a rate of about 0.05-0.1°C decade-1 at Tokyo and about 0.02°C decade-1 at stations where the population density was 100 to 1,000 km-2, but no significant difference in ?T* trends was observed between weekdays and weekend days.

Fujibe, Fumiaki

2010-11-01

218

Zero temperature properties of mesons and baryons from an extended linear sigma-model  

NASA Astrophysics Data System (ADS)

An extended linear sigma model with mesons (qbar q states) and baryons (qqq states) is presented. The model contains a low energy multiplet for every hadronic particle type, namely a scalar, a pseudoscalar, a vector and an axialvector nonet, a baryon octet and a baryon decuplet. The model parameters are determined through a multiparametric minimalization with the help of well known physical quantities. It is found that the considered zero temperature quantities (masses and decay widths) can be described well at tree-level and are in good agreement with the experimental data.

Kovács, P.; Wolf, Gy

2014-04-01

219

Influence of temperature on linear stability in buoyancy-driven fingering of reaction-diffusion fronts.  

PubMed

A vertical Hele-Shaw cell was used to study the influence of temperature on Rayleigh-Taylor instabilities on reaction-diffusion fronts. The propagation of the chemical front can thus be observed, and experimental results can be obtained via image treatment. A chemical front produced by the coupling between molecular diffusion and the auto-catalysis of the chlorite-tetrathionate reaction, descends through the cell, consuming the reactants below while the product is formed above. Buoyancy-driven instabilities are formed due to the density difference between reactants and products, and the front takes a fingering pattern, whose growth rate has temperature dependence. In this study, the effect of temperature on the linear regime of the instability (that is, when the effects of such instability start to appear) was analyzed. To measure the instability, Fourier transform analysis is performed, in order to obtain the different wave numbers and their power as a function of time. Thus, the growth rate for each wave number and the most unstable wave number is obtained for each of the temperatures under study. Based on repeated experiments, a decrease in the growth rate for the most unstable wave number can be observed with the increase of temperature. PMID:23020498

Levitán, D; D'Onofrio, A

2012-09-01

220

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.

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

2012-01-01

221

Competition of linearly polarized modes in fibers with Bragg gratings over a wide temperature range  

NASA Astrophysics Data System (ADS)

Fiber Bragg gratings (FBGs) embedded in conventional fibers may serve as temperature sensors over a wide temperature range and withstand temperatures around 1200 K. A variety of linearly polarized (LP) modes for the wavelengths between 400 and 700 nm may be sustained in fibers with and without FBGs. The composition of the LP modes and their competition is instrumental for understanding physics of thermo-optics and thermal expansion effects in silica-based fibers. The first objective of this work was to model mathematically the competition between LP modes and modal distribution using the solutions of Bessel equations for the fibers with and without the gratings. Computer generated modes were constructed and the cut-off V-numbers (and Eigen values W and U) were determined. Theoretical results then were compared with experimental observations of LP modes for two separate ranges of temperatures: 77- 300 K and 300-1200 K. To study the formation of LP modes over the first temperature range, liquid nitrogen was used to cool down the fiber and a thermocouple was used to monitor the temperature of the fiber. Real time recording of the modal structure was performed using digital imaging and data acquisition instrumentation. To study LP modes between 300- 1200 K, the fibers were inserted into a tube furnace with temperature control. The wavelength of the infrared radiation was reflected by a FBG and detected by an optical spectrum analyzer. Radiation at the visible wavelength propagated through the fibers, and transmitted visible light was collected, analyzed and recorded with a CCD camera to monitor distribution of the LP modes in the samples with and without the FBGs.

Lyuksyutov, Sergei; Adamovsky, Grigory; Mackey, Jeffrey R.; Floyd, Bertram; Abeywickrema, Ujitha; Fedin, Igor

2012-10-01

222

Estimating spatially distributed monthly evapotranspiration rates by linear transformations of MODIS daytime land surface temperature data  

NASA Astrophysics Data System (ADS)

Under simplifying conditions catchment-scale vapor pressure at the drying land surface can be calculated as a function of its watershed-representative temperature () by the wet-surface equation (WSE, similar to the wet-bulb equation in meteorology for calculating the dry-bulb thermometer vapor pressure) of the Complementary Relationship of evaporation. The corresponding watershed ET rate, , is obtained from the Bowen ratio with the help of air temperature, humidity and percent possible sunshine data. The resulting (,) pair together with the wet-environment surface temperature () and ET rate (ETw), obtained by the Priestley-Taylor equation, define a linear transformation on a monthly basis by which spatially distributed ET rates can be estimated as a sole function of MODIS daytime land surface temperature, Ts, values within the watershed. The linear transformation preserves the mean which is highly desirable. , in the lack of significant open water surfaces within the study watershed (Elkhorn, Nebraska), was obtained as the mean of the smallest MODIS Ts values each month. The resulting period-averaged (2000-2007) catchment-scale ET rate of 624 mm/yr is very close to the water-balance derived ET rate of about 617 mm/yr. The latter is a somewhat uncertain value due to the effects of (a) observed groundwater depletion of about 1m over the study period caused by extensive irrigation, and; (b) the uncertain rate of net regional groundwater supply toward the watershed. The spatially distributed ET rates correspond well with soil/aquifer properties and the resulting land use type (i.e. rangeland versus center-pivot irrigated crops).

Szilagyi, J.; Jozsa, J.

2009-05-01

223

Estimating spatially distributed monthly evapotranspiration rates by linear transformations of MODIS daytime land surface temperature data  

NASA Astrophysics Data System (ADS)

Under simplifying conditions catchment-scale vapor pressure at the drying land surface can be calculated as a function of its watershed-representative temperature () by the wet-surface equation (WSE, similar to the wet-bulb equation in meteorology for calculating the dry-bulb thermometer vapor pressure) of the complementary relationship of evaporation. The corresponding watershed ET rate, , is obtained from the Bowen ratio with the help of air temperature, humidity and percent possible sunshine data. The resulting (, ) pair together with the wet-environment surface temperature () and ET rate (ETw), obtained by the Priestley-Taylor equation, define a linear transformation on a monthly basis by which spatially distributed ET rates can be estimated as a sole function of MODIS daytime land surface temperature, Ts, values within the watershed. The linear transformation preserves the mean which is highly desirable. , in the lack of significant open water surfaces within the study watershed (Elkhorn, Nebraska), was obtained as the mean of the smallest MODIS Ts values each month. The resulting period-averaged (2000-2007) catchment-scale ET rate of 624 mm/yr is very close to the water-balance derived ET rate of about 617 mm/yr. The latter is a somewhat uncertain value due to the effects of (a) observed groundwater depletion of about 1m over the study period caused by extensive irrigation, and; (b) the uncertain rate of net regional groundwater supply toward the watershed. The spatially distributed ET rates correspond well with soil/aquifer properties and the resulting land use type (i.e., rangeland versus center-pivot irrigated crops).

Szilagyi, J.; Jozsa, J.

2009-03-01

224

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

225

Validation of electron temperature gradient turbulence in the Columbia Linear Machine  

NASA Astrophysics Data System (ADS)

The electron temperature gradient (ETG) mode, which is a universal mechanism for turbulent electron thermal transport in plasmas, is produced and verified in steady-state, collisionless hydrogen plasma of the Columbia Linear Machine. Electron temperature profiles with strong gradients are produced by DC acceleration in a remote biased mesh and subsequent thermalization. Finite amplitude ~5%, steady-state oscillations at ~0.3-0.5MHz (in the plasma frame), with azimuthal wave numbers m~14-16 and parallel wave number k?~0.01cm-1 are measured. The massively parallel gyrokinetic toroidal code is used to study these modes. The results show that in the linear phase, the dispersion relation is consistent with kinetic theory. In the nonlinear stage, very strong nonlinear wave coupling gives rise to an inverse cascade of the energy from the fastest growing high-m modes to low-m nonlinear oscillations, which are consistent with the measured azimuthal mode spectrum. The radial structure of the fluctuation also agrees with the experiment. An inward radial shift of the peak of the potential fluctuation occurs during the nonlinear saturation and fluctuation fingers extend radially out to the edge plasma. Three-wave coupling mechanism is involved in the saturation of ETG modes. The simulations show a power law spectrum of the turbulence which suggests that the renormalization theory is appropriate to interpret the turbulent thermal flux.

Fu, X. R.; Horton, W.; Xiao, Y.; Lin, Z.; Sen, A. K.; Sokolov, V.

2012-03-01

226

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

Microsoft Academic Search

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

G. I. Molnar; J. Susskind; L. F. Iredell

2010-01-01

227

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

228

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

229

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

230

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

231

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

232

Comparison of geographical trend patterns in sea level and sea surface temperature in the Pacific Ocean during 1993-2011  

NASA Astrophysics Data System (ADS)

It is now well established that geographical trend patterns in satellite altimetry-based sea level are mostly caused by non uniform steric trend patterns, the largest contribution being due to the thermosteric component. In the Pacific Ocean, the observed sea level trend pattern over 1993-2011 results from a superposition two types of signals: (1) a strong positive trend V-shaped anomaly located 120°E and 160° E in longitude and ~20°S-20°N in latitude and (2) another V-shaped anomaly of much broader scale -extending to mid-latitudes in the central Pacific-, quite similar to the dominant large-scale trend pattern observed in sea surface temperature (SST). Previous studies have shown that the type (1) signal is related to El Nino Southern Oscillation (ENSO). The type (2) signal reflects the Pacific Decadal Oscillation (PDO), the dominant component of large-scale SST variability in the Pacific. In this study, we analyze altimetry-based sea level, steric sea level and SST over the 1993-2011 time span to discriminate between the near surface and deeper thermosteric contributions to sea level. The sea level and SST data are based on the recently available products from the ESA Climate Change Initiative project and several other products like HadiSST, ERAINTERIM. Steric data are based on an updated version of the Ishii and Kimoto (2009) data. We compute the thermosteric contribution to sea level in different layers from the surface to the 700 m depth, and through correlation and Empirical Orthogonal Function analyses, explore the spatio-temporal coherence between the three variables (sea level, depth-dependent steric sea level and SST).

Palanisamy, Hindumathi; Cazenave, Anny; Delcroix, Thierry; Meyssignac, Benoit; Balmaseda, Magdalena; Merchant, Christopher

2013-04-01

233

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

234

Word of mouth and viral marketing: taking the temperature of the hottest trends in marketing  

Microsoft Academic Search

Purpose – The purpose of this paper is to study examples of emerging marketing trends like word-of-mouth and viral marketing, and attempt to determine their measurability in terms of return on investment (ROI). Design\\/methodology\\/approach – The study examines real life campaigns from well-known companies and attempt to measure consumer response beyond merely viewing or participating in the campaign. How much

Rick Ferguson

2008-01-01

235

Non-uniform interhemispheric temperature trends over the past 550 years  

Microsoft Academic Search

The warming trend over the last century in the northern hemisphere (NH) was interrupted by cooling from ad 1940 to 1975, a period during which the southern hemisphere experienced pronounced warming. The cause of these departures\\u000a from steady warming at multidecadal timescales are unclear; the prevailing explanation is that they are driven by non-uniformity\\u000a in external forcings but recent models

Richard P. Duncan; Pavla Fenwick; Jonathan G. Palmer; Matt S. McGlone; Chris S. M. Turney

2010-01-01

236

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

237

Microhotplate-based silicon gas sensor arrays with linear temperature gradient for wine quality monitoring  

NASA Astrophysics Data System (ADS)

In this work, we describe the design implementation, validated by experimental results, of an innovative gas sensor array for wine quality monitoring. The main innovation of this integrated array deals with the simultaneous outputs, from a single chip on TO-12 socket, of 8 different signals coming from a WO3 thin film structure heated in a linear temperature gradient mode, allowing an overall evaluation of gas sensing properties of the material in a 100°C-wide window, typically from 300 to 400°C. The implemented sensitive layer is a WO3 film deposed by RF-sputtering. Preliminary tests of gas sensing showed good responses to the target analytes for the specific application (1-heptanol, 3-methyl butanol, benzaldehyde and ethyl-hexanoate).

Adami, Andrea; Lorenzelli, Leandro; Guarnieri, Vittorio; Zen, Mario; Francioso, Luca; Siciliano, Pietro; Forleo, A.; Taurino, A. M.; Agnusdei, Giuseppe

2005-07-01

238

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

239

Directly Determined Linear Radii and Effective Temperatures of Giants from Long-Baseline Optical Interferometry  

NASA Astrophysics Data System (ADS)

A review of fundamental stellar parameters for giants as directly determined using long-baseline optical interferometry (LBI) will be presented. Special attention will be paid to the progression of precision over the years of the observables of linear radius and effective temperature, with the current state-of-the-art measures approaching sub-percent levels for hundreds of stars (and being limited primarily by the ancillary data products of distance and bolometric flux, not measured angular size). Discussion will also be presented on the diminishing meaning of these gross parameterizations of stellar atmospheres, as higher-order surface details such as limb darkening and spotting are beginning to be imaged with LBI.

van Belle, Gerard

2013-07-01

240

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

241

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

242

The PTI Carbon Star Angular Size Survey: Effective Temperatures, Linear Radii, and Oblateness  

NASA Astrophysics Data System (ADS)

We report new interferometric angular diameter observations of 41 carbon stars observed with the Palomar Testbed Interferometer (PTI). Two of these stars are CH carbon stars and represent the first such measurements for this subtype. Of these, 39 have Yamashita (1972, 1975) spectral classes and are of sufficiently high quality that we may determine the dependence of effective temperature on spectral type. We find that there is a tendency for the effective temperature to increase with increasing temperature index by ~120K per step, starting at T_EF 2500K for C3,y. Overall, the median effective temperature for the carbon star sample is found to be 2800+-270K, and the median linear radius is 360+-100 R_sun. We also find agreement on average within 15K with the T_EFF determinations of Bergeat (2001, 2002a,b), and a refinement of carbon star angular size prediction based on V & K magnitudes is presented that is good to an rms of 12%. A subsample of our stars have sufficient {u,v} coverage to permit non-spherical modeling of their photospheres, and a general tendency for detection of statistically significant oblateness with increasing signal-to-noise of the interferometric data is seen. The implications of most carbon stars being spherically oblate is considered in the context of angular moment history and mass loss rates. In particular, compared to the dM/dt rates found in Claussen (1987), a possible correlation between increasing mass loss rates and increasing oblateness is observed.

van Belle, Gerard; Paladini, C.; Aringer, B.; Hron, J.; Lebzelter, T.; Ciardi, D.; PTI Collaboration

2013-01-01

243

Linear Stability of a Double Diffusive Layer of an Infinite Prandtl Number Fluid with Temperature-Dependent Viscosity  

Microsoft Academic Search

An infinite horizontal layer, with vertically stratified temperature and solute concentration, is considered in the case where the viscosity is exponentially dependent on temperature, and the Prandtl number is infinite. Its linear stability is investigated when the destabilizing thermal gradient acts against a stabilizing solute gradient. The analysis is performed using horizontal Fourier and vertical Chebyshev polynomial expansions. For the

A. Mambole; G. Labrosse; E. Tric; L. Fleitout

2004-01-01

244

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.

245

Sea surface temperature anomalies, seasonal cycle and trend regimes in the eastern Pacific coast  

Microsoft Academic Search

We used the extended reconstruction of sea surface temperature (ERSST) to analyze the variation of surface temperature and the seasonal cycle along the coast of the eastern Pacific (60° N-60° S, 61 pixels alongshore) from 1950 to 2010 (732 months). First we analyzed the monthly anomalies and looked for a relationship of such anomalies with total solar radiation (TSI) and

A. Ramos-Rodríguez; D. B. Lluch-Cota; S. E. Lluch-Cota; A. Trasviña-Castro

2011-01-01

246

Use and Limitations of a Climate-Quality Data Record to Study Temperature Trends on the Greenland Ice Sheet  

NASA Technical Reports Server (NTRS)

Enhanced melting of the Greenland Ice Sheet has been documented in recent literature along with surface-temperature increases measured using infrared satellite data since 1981. Using a recently-developed climate-quality data record, 11- and 12-year trends in the clear-sky ice-surface temperature (IST) of the Greenland Ice Sheet have been studied using the Moderate-Resolution Imaging Spectroradiometer (MODIS) IST product. Daily and monthly MODIS ISTs of the Greenland Ice Sheet beginning on 1 March 2000 and continuing through 31 December 2010 are now available at 6.25-km spatial resolution on a polar stereographic grid as described in Hall et al. (submitted). This record will be elevated in status to a climate-data record (CDR) when more years of data become available either from the MODIS on the Terra or Aqua satellites, or from the Visible Infrared Imager Radiometer Suite (VIIRS) to be launched in October 2011. Maps showing the maximum extent of melt for the entire ice sheet and for the six major drainage basins have been developed from the MODIS IST dataset. Twelve-year trends of the duration of the melt season on the ice sheet vary in different drainage basins with some basins melting progressively earlier over the course of the study period. Some (but not all) of the basins also show a progressively-longer duration of melt. IST 12-year trends are compared with in-situ data, and climate data from the Modern Era Retrospective-Analysis for Research and Applications (MERRA) Reanalysis.

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

2011-01-01

247

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

NSDL National Science Digital Library

In this lesson, students investigate and analyze the connection between sea surface temperatures and the flow pattern of the Gulf Stream current. Students will generate an Excel file of sea surface temperatures for the Gulf Stream region from data stored on the Live Access Server. In addition, students will also access and plot seasonal water temperature changes from different time periods. This will allow for a comparison of maximum and minimum temperature fluctuations as well as seasonal variations for locations throughout the Gulf Stream. Students will also explore the Gulf Streamâs affects on weather and offshore industries. This lesson uses student- and citizen science-friendly microsets of authentic NASA Earth system science data from the MY NASA DATA project. It also includes related links, extension, an online glossary, and a list of related AP Environmental Science topics.

248

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

249

Power-law persistence and trends in the atmosphere: A detailed study of long temperature records  

Microsoft Academic Search

We use several variants of the detrended fluctuation analysis to study the appearance of long-term persistence in temperature records, obtained at 95 stations all over the globe. Our results basically confirm earlier studies. We find that the persistence, characterized by the correlation C(s) of temperature variations separated by s days, decays for large s as a power law, C(s)˜s-gamma. For

J. F. Eichner; Eva Koscielny-Bunde; Armin Bunde; Shlomo Havlin; H.-J. Schellnhuber

2003-01-01

250

Natural selection and climate change: temperature-linked spatial and temporal trends in gene frequency in Fagus sylvatica.  

PubMed

Rapid increases in global temperature are likely to impose strong directional selection on many plant populations, which must therefore adapt if they are to survive. Within populations, microgeographic genetic differentiation of individuals with respect to climate suggests that some populations may adapt to changing temperatures in the short-term through rapid changes in gene frequency. We used a genome scan to identify temperature-related adaptive differentiation of individuals of the tree species Fagus sylvatica. By combining molecular marker and dendrochronological data we assessed spatial and temporal variation in gene frequency at the locus identified as being under selection. We show that gene frequency at this locus varies predictably with temperature. The probability of the presence of the dominant marker allele shows a declining trend over the latter half of the 20th century, in parallel with rising temperatures in the region. Our results show that F. sylvatica populations may show some capacity for an in situ adaptive response to climate change. However as reported ongoing distributional changes demonstrate, this response is not enough to allow all populations of this species to persist in all of their current locations. PMID:16968284

Jump, Alistair S; Hunt, Jenny M; Martínez-Izquierdo, José A; Peñuelas, Josep

2006-10-01

251

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

252

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

NASA Astrophysics Data System (ADS)

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 discontinuities or changes, were used for the analysis. Greece, in general, shows a cooling trend in winter for the period 1955 2001, whereas, summer shows an overall warming trend, however, neither is statistically significant. As a result, the overall trend of the annual values is nearly zero. Comparison with corresponding trends in the Northern Hemisphere (NH) shows that temperatures in Greece do not follow the intense warming trends. Satellite data indicate a remarkable warming trend in mean annual, winter and summer in Greece for the period 1980 2001, and a slight warming trend in annual, spring and autumn for the NH. Comparison with the respective trends detected in the surface air temperature for the same period (1980 2001) shows they match each other quite well in both Greece and the NH. The relationship between temperature variability in Greece and atmospheric circulation was also examined using correlation analysis with three circulation indices: the well-known North Atlantic Oscillation Index (NAOI), a Mediterranean Oscillation Index (MOI) and a new Mediterranean Circulation Index (MCI). The MOI and MCI indices show the most interesting correlation with winter temperatures in Greece. The behaviour of pressure and the height of the 500 hPa surface over the Mediterranean region supports these results.

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

2004-12-01

253

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

254

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

255

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

256

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

257

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

258

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

259

Amplification of Surface Temperature Trends and Variability in the Tropical Atmosphere  

Microsoft Academic Search

The month-to-month variability of tropical temperatures is larger in the troposphere than at Earth's surface. This amplification behavior is similar in a range of observations and climate model simulations and is consistent with basic theory. On multidecadal time scales, tropospheric amplification of surface warming is a robust feature of model simulations, but it occurs in only one observational data set.

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

2005-01-01

260

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

261

Temperature Trends in the Polar Mesosphere between 2002-2007 using TIMED/SABER Data  

NASA Technical Reports Server (NTRS)

The TIMED Satellite was launched on December 7, 2001 to study the dynamics and energy of the mesosphere and lower thermosphere. The TIMED/SABER instrument is a limb scanning infrared radiometer designed to measure a large number of minor constituents as well as the temperature of the region. In this study, we have concentrated on the polar mesosphere, to investigate the temperature characteristics as a function of spatial and temporal considerations. We used the recently revised SABER dataset (1.07) that contains improved temperature retrievals in the Earth polar summer regions. Weekly averages are used to make comparisons between the winter and summer, as well as to study the variability in different quadrants of each hemisphere. For each year studied, the duration of polar summer based on temperature measurements compares favorably with the PMSE (Polar Mesospheric Summer Echoes) season measured by radar at the ALOMAR Observatory in Norway (69 N). The PMSE period should also define the summer period suitable for the occurrence of polar mesospheric clouds. The unusual short and relatively warm polar summer in the northern hemisphere

Goldberg, Richard A.; Kutepov, Alexander A.; Pesnell, William Dean; Latteck, Ralph; Russell, James M.

2008-01-01

262

Upper-Air Temperature Trends over the Globe, 1958-1989  

Microsoft Academic Search

New time series of the hemispheric and global mean temperature anomalies in the troposphere and lower stratosphere are presented for the period May 1958 through December 1989. The statistics are based on objective monthly analyses of all available daily soundings from the global rawinsonde network (700-800 stations). The results are compared with Angell's earlier statistics based on a subset of

Abraham H. Oort; Huanzhu Liu

1993-01-01

263

Trends in temperature and dew point at the summit of Mount Washington, New Hampshire, 1935-2004.  

NASA Astrophysics Data System (ADS)

Dry and wet bulb temperatures from sling psychrometer measurements taken every six hours from 1935 to 2004 at the summit of Mount Washington, located at 44 °16'N, 71 °18'W, 1914 m ASL have recently been digitized. Annual temperature has increased by 0.3°C, and annual dew point has decreased by 0.4°C over this 70-year period. Synoptic temperature has increased most in spring and winter, changing by 1.0°C and 0.5°C, respectively, while it has decreased slightly in summer and fall. Dew point has decreased in fall, summer, and winter, 0.9°C, 0.5°C, and 0.4°C respectively, and increased by 0.1°C in spring. Preliminary analysis suggests that some of the larger trends in winter and spring may be statistically significant; results of Monte Carlo simulations will be reported. Changes in dew point may be attributed to two factors. Decreasing dew points are expected if the temperature increases but the amount of water vapor present stays the same. Alternatively, lower dew points could be indicative of the presence of drier air. Other dew point climatologies of the continental United States for the second half of the century have shown mixed results, with increased dew points evident at some stations, decreased dew points at others, and no clear regional patterns.

Grant, A. N.; Pszenny, A. A.; Fischer, E. V.

2005-05-01

264

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

265

Error trends in SASS winds as functions of atmospheric stability and sea surface temperature  

NASA Technical Reports Server (NTRS)

Wind speed measurements obtained with the scatterometer instrument aboard the Seasat satellite are compared equivalent neutral wind measurements obtained from ship reports in the western N. Atlantic and eastern N. Pacific where the concentration of ship reports are high and the ranges of atmospheric stability and sea surface temperature are large. It is found that at low wind speeds the difference between satellite measurements and surface reports depends on sea surface temperature. At wind speeds higher than 8 m/s the dependence was greatly reduced. The removal of systematic errors due to fluctuations in atmospheric stability reduced the r.m.s. difference from 1.7 m/s to 0.8 m/s. It is suggested that further clarification of the effects of fluctuations in atmospheric stability on Seasat wind speed measurements should increase their reliability in the future.

Liu, W. T.

1983-01-01

266

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

267

The integral six-color pyrometer: Linear dependence of the radiance temperature Tr on the wavelength lambda  

Microsoft Academic Search

The emissivity E of a radiating body as a function of wavelength can be expressed as (ln E)\\/C2=a+bL+cL2+dL3+@\\/e L4+ ... . In our first papers we assumed that the variation is linear; only two coefficients are needed. Later we developed ‘‘A New, General Method of Temperature Determination,’’ which consists of evaluating Te, the calculated blackbody temperature, using one, two, three,

Michael Hoch

1992-01-01

268

Distinguishing the impacts of ozone-depleting substances and well-mixed greenhouse gases on Arctic stratospheric ozone and temperature trends  

NASA Astrophysics Data System (ADS)

stratospheric cooling due to increases in well-mixed greenhouse gases (WMGHG) could increase the depletion of Arctic stratospheric ozone has been the subject of scientific and public attention for decades. Here we provide evidence that changes in the concentrations of ozone-depleting substances (ODS), not WMGHG, have been the primary driver of observed Arctic lower stratospheric trends in both ozone and temperature. We do so by analyzing polar cap ozone and temperature trends in reanalysis data: these clearly suggest that both trends are mainly driven by ODS in the lower stratosphere. This observation-based finding is supported by results from a stratosphere-resolving chemistry-climate model driven with time-varying ODS and WMGHG, specified in isolation and in combination. Taken together, these results provide strong evidence that ODS are the main driver of changes in the Arctic lower stratospheric temperatures and ozone, whereas WMGHG are the primary driver of changes in the upper stratosphere.

Rieder, Harald E.; Polvani, Lorenzo M.; Solomon, Susan

2014-04-01

269

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

270

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

271

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...

272

Optimal design of non-linear Temperature Programmed Reduction (TPR) experiments  

Microsoft Academic Search

The experimental method of temperature programmed reduction (TPR) is extended by application of non-constant temperature gradients. An optimal control problem is formulated with the D-optimality criterion as the objective function and ordinary differential equations (ODEs) as constraints. The problem is solved for systems with a single reaction and with two consecutive reactions. The results show that optimal nonlinear temperature profiles

Peter Heidebrecht; Kai Sundmacher; Lorenz T. Biegler

2009-01-01

273

Analyzing projected changes and trends of temperature and precipitation in the southern USA from 16 downscaled global climate models  

NASA Astrophysics Data System (ADS)

This study aims to examine how future climate, temperature and precipitation specifically, are expected to change under the A2, A1B, and B1 emission scenarios over the six states that make up the Southern Climate Impacts Planning Program (SCIPP): Oklahoma, Texas, Arkansas, Louisiana, Tennessee, and Mississippi. SCIPP is a member of the National Oceanic and Atmospheric Administration-funded Regional Integrated Sciences and Assessments network, a program which aims to better connect climate-related scientific research with in-the-field decision-making processes. The results of the study found that the average temperature over the study area is anticipated to increase by 1.7°C to 2.4°C in the twenty-first century based on the different emission scenarios with a rate of change that is more pronounced during the second half of the century. Summer and fall seasons are projected to have more significant temperature increases, while the northwestern portions of the region are projected to experience more significant increases than the Gulf coast region. Precipitation projections, conversely, do not exhibit a discernible upward or downward trend. Late twenty-first century exhibits slightly more precipitation than the early century, based on the A1B and B1 scenario, and fall and winter are projected to become wetter than the late twentieth century as a whole. Climate changes on the city level show that greater warming will happened in inland cities such as Oklahoma City and El Paso, and heavier precipitation in Nashville. These changes have profound implications for local water resources management as well as broader regional decision making. These results represent an initial phase of a broader study that is being undertaken to assist SCIPP regional and local water planning efforts in an effort to more closely link climate modeling to longer-term water resources management and to continue assessing climate change impacts on regional hazards management in the South.

Liu, Lu; Hong, Yang; Hocker, James E.; Shafer, Mark A.; Carter, Lynne M.; Gourley, Jonathan J.; Bednarczyk, Christopher N.; Yong, Bin; Adhikari, Pradeep

2012-08-01

274

Melting of major Glaciers in the western Himalayas: evidence of climatic changes from long term MSU derived tropospheric temperature trend (1979-2008)  

NASA Astrophysics Data System (ADS)

Global warming or the increase of the surface and atmospheric temperatures of the Earth, is increasingly discernible in the polar, sub-polar and major land glacial areas. The Himalayan and Tibetan Plateau Glaciers, which are the largest glaciers outside of the Polar Regions, are showing a large-scale decrease of snow cover and an extensive glacial retreat. These glaciers such as Siachen and Gangotri are a major water resource for Asia as they feed major rivers such as the Indus, Ganga and Brahmaputra. Due to scarcity of ground measuring stations, the long-term observations of atmospheric temperatures acquired from the Microwave Sounding Unit (MSU) since 1979-2008 is highly useful. The lower and middle tropospheric temperature trend based on 30 years of MSU data shows warming of the Northern Hemisphere's mid-latitude regions. The mean month-to-month warming (up to 0.048±0.026°K/year or 1.44°K over 30 years) of the mid troposphere (near surface over the high altitude Himalayas and Tibetan Plateau) is prominent and statistically significant at a 95% confidence interval. Though the mean annual warming trend over the Himalayas (0.016±0.005°K/year), and Tibetan Plateau (0.008±0.006°K/year) is positive, the month to month warming trend is higher (by 2-3 times, positive and significant) only over a period of six months (December to May). The factors responsible for the reversal of this trend from June to November are discussed here. The inequality in the magnitude of the warming trends of the troposphere between the western and eastern Himalayas and the IG (Indo-Gangetic) plains is attributed to the differences in increased aerosol loading (due to dust storms) over these regions. The monthly mean lower-tropospheric MSU-derived temperature trend over the IG plains (dust sink region; up to 0.032±0.027°K/year) and dust source regions (Sahara desert, Middle East, Arabian region, Afghanistan-Iran-Pakistan and Thar Desert regions; up to 0.068±0.033°K/year) also shows a similar pattern of month-to-month oscillation and six months of enhanced and a statistically significant warming trend. The enhanced warming trend during the winter and pre-monsoon months (December-May) may accelerate glacial melt. The unequal distribution of the warming trend over the year is discussed in this study and is partially attributed to a number of controlling factors such as sunlight duration, CO2 trends over the region (2003-2008), water vapor and aerosol distribution.

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

2009-12-01

275

Spatial and seasonal characteristics of recent decadal trends in the northern hemispheric troposphere and stratosphere  

Microsoft Academic Search

Linear trends in the northern hemispheric 500 hPa geopotential height, lower tropospheric temperature, and zonal-mean-zonal winds are investigated for the period 1965-1993. There is a general opinion that decadal trends in the atmospheric circulation are produced by changes in the equatorial sea surface temperatures (SSTs). In order to determine other factors, a trend analysis is conducted in the present study

Kunihiko Kodera; Hiroshi Koide

1997-01-01

276

Real-Time Interrogation of a Linearly Chirped Fiber Bragg Grating Sensor for Simultaneous Measurement of Strain and Temperature  

Microsoft Academic Search

We propose and demonstrate a novel approach to real-time interrogation of a high-birefringence linearly chirped fiber Bragg grating (Hi-Bi LCFBG) for simultaneous measure- ment of strain and temperature based on chirped microwave pulse compression with increased resolution and signal-to-noise ratio (SNR). A theoretical analysis is developed, which is validated by an experiment. The experimental results show that the proposed system

Weilin Liu; Wangzhe Li; Jianping Yao

2011-01-01

277

A non-linear optimal estimation inverse method for radio occultation measurements of temperature, humidity and surface pressure  

Microsoft Academic Search

An optimal estimation inverse method is presented which can be used to\\u000aretrieve simultaneously vertical profiles of temperature and specific humidity,\\u000ain addition to surface pressure, from satellite-to-satellite radio occultation\\u000aobservations of the Earth's atmosphere. The method is a non-linear, maximum\\u000a{\\\\it a posteriori} technique which can accommodate most aspects of the real\\u000aradio occultation problem and is found to

Paul I. Palmer; J. J. Barnett; J. R. Eyre; S. B. Healy

2000-01-01

278

Algorithm for linear response functions at finite temperatures: application to ESR spectrum of s=1/2 antiferromagnet Cu benzoate.  

PubMed

We introduce an efficient and numerically stable method for calculating linear response functions chi(q,omega) of quantum systems at finite temperatures. The method is a combination of numerical solution of the time-dependent Schrödinger equation, random vector representation of trace, and Chebyshev polynomial expansion of Boltzmann operator. This method should be very useful for a wide range of strongly correlated quantum systems at finite temperatures. We present an application to the ESR spectrum of s=1 / 2 antiferromagnet Cu benzoate. PMID:12570454

Iitaka, Toshiaki; Ebisuzaki, Toshikazu

2003-01-31

279

Pt/ZnO nanoarray nanogenerator as self-powered active gas sensor with linear ethanol sensing at room temperature.  

PubMed

A self-powered gas sensor that can actively detect ethanol at room temperature has been realized from a Pt/ZnO nanoarray nanogenerator. Pt nanoparticles are uniformly distributed on the whole surface of ZnO nanowires. The piezoelectric output of Pt/ZnO nanoarrays can act not only as a power source, but also as a response signal to ethanol at room temperature. Upon exposure to dry air and 1500 ppm ethanol at room temperature, the piezoelectric output of the device under the same compressive strain is 0.672 and 0.419 V, respectively. Moreover, a linear dependence of the sensitivity on the ethanol concentration is observed. Such a linear ethanol sensing at room temperature can be attributed to the atmosphere-dependent variety of the screen effect on the piezoelectric output of ZnO nanowires, the catalytic properties of Pt nanoparticles, and the Schottky barriers at Pt/ZnO interfaces. The present results can stimulate research in the direction of designing new material systems for self-powered room-temperature gas sensing. PMID:24561677

Zhao, Yayu; Lai, Xuan; Deng, Ping; Nie, Yuxin; Zhang, Yan; Xing, Lili; Xue, Xinyu

2014-03-21

280

Pt/ZnO nanoarray nanogenerator as self-powered active gas sensor with linear ethanol sensing at room temperature  

NASA Astrophysics Data System (ADS)

A self-powered gas sensor that can actively detect ethanol at room temperature has been realized from a Pt/ZnO nanoarray nanogenerator. Pt nanoparticles are uniformly distributed on the whole surface of ZnO nanowires. The piezoelectric output of Pt/ZnO nanoarrays can act not only as a power source, but also as a response signal to ethanol at room temperature. Upon exposure to dry air and 1500 ppm ethanol at room temperature, the piezoelectric output of the device under the same compressive strain is 0.672 and 0.419 V, respectively. Moreover, a linear dependence of the sensitivity on the ethanol concentration is observed. Such a linear ethanol sensing at room temperature can be attributed to the atmosphere-dependent variety of the screen effect on the piezoelectric output of ZnO nanowires, the catalytic properties of Pt nanoparticles, and the Schottky barriers at Pt/ZnO interfaces. The present results can stimulate research in the direction of designing new material systems for self-powered room-temperature gas sensing.

Zhao, Yayu; Lai, Xuan; Deng, Ping; Nie, Yuxin; Zhang, Yan; Xing, Lili; Xue, Xinyu

2014-03-01

281

A Trend Between Cold Debris Disk Temperature and Stellar Type: Implications for the Formation and Evolution of Wide-Orbit Planets  

NASA Astrophysics Data System (ADS)

Cold debris disks have the potential to answer many outstanding questions in wide-orbit planet formation and evolution. We characterized the infrared excess SEDs of 174 cold debris disks with Spitzer IRS and MIPS. We found a trend between the temperature of the disks and the stellar type of the stars they orbit. This argues against the importance of strictly temperature-dependent processes (e.g. ice lines) in setting the dimensions of cold debris disks. We also 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 from planet formation that halts at an orbital radius limited by the efficiency of core accretion. For the full details of this work, see Ballering et al. (2013).

Ballering, Nicholas P.; Rieke, George H.; Su, Kate Y. L.; Montiel, Edward

2014-01-01

282

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

283

The natural circulation solar water heater model with linear temperature distribution  

Microsoft Academic Search

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

A. Zerrouki; A. Boumédien; K. Bouhadef

2002-01-01

284

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

285

First Principles Derivation of Nls Equation for Bec with Cubic and Quintic Nonlinearities at Nonzero Temperature: Dispersion of Linear Waves  

NASA Astrophysics Data System (ADS)

We present a derivation of the quantum hydrodynamic (QHD) equations for neutral bosons. We consider the short-range interaction between particles. This interaction consist of a binary interaction U( ri, rj) and a three-particle interaction (TPI) U( ri, rj, rk) and the last one does not include binary interaction between particles. From QHD equations for Bose-Einstein condensate we derive a nonlinear Schrödinger equation. This equation was derived for zero temperature and contains the nonlinearities of the third and the fifth degree. Explicit form of the constant of the TPI is obtained. First of all, developed method we used for studying of dispersion of the linear waves. Dispersion characteristics of the linear waves are compared for different particular cases. We make comparison of the two-particle interaction in the third order by the interaction radius (TOIR) and TPI at the zero temperature. We consider influence of the temperature on the dispersion of the elementary excitations. For this aim we derive a system of the QHD equations at nonzero temperature. Obtained system of equation is an analog of the well-known two-fluid hydrodynamics. Moreover, it is generalization of the two-fluid hydrodynamics equations due to TPI. Explicit expressions of the velocities for the first and the second sound via the concentration of superfluid and noncondensate components is calculated.

Andreev, P. A.

2013-03-01

286

GENERAL: Temperature Effects of Parabolic Linear Bound Potential and Coulomb Bound Potential Quantum Dot Qubit  

NASA Astrophysics Data System (ADS)

On the condition of electric-LO phonon strong coupling in a parabolic quantum dot, we obtain the eigenenergy and the eigenfunctions of the ground state and the first-excited state using the variational method of Pekar type. This system in a quantum dot may be employed as a two-level quantum system-qubit. When the electron is in the superposition state of the ground state and the first-excited state, we obtain the time evolution of the electron density. The relations of the probability density of electron on the temperature and the electron-LO-phonon coupling constant and the relations of the period of oscillation on the temperature, the electron-LO-phonon coupling constant, the Coulomb binding parameter and the confinement length are derived. The results show that the probability density of electron oscillates with a period when the electron is in the superposition state of the ground and the first-excited state, and show that there are different laws that the probability density of electron and the period of oscillation change with the temperature and the electron-LO-phonon coupling constant when the temperature is lower or higher. And it is obtained that the period of oscillation decreases with increasing the Coulomb bound potential and increases with increasing the confinement length not only at lower temperatures but also at higher temperatures.

Chen, Ying-Jie; Xiao, Jing-Lin

2009-10-01

287

Thermal stresses in a flat plate subjected to convective heating induced by piecewise linear variation of ambient temperature  

SciTech Connect

The problem of determining the stress state in a plate subjected to thermal transient is often encountered in enginering practice. Available solutions are limited to special cases and are not easy to use. The aim of this work is to provide a simple tool for stress and strain calculations due to piecewise linear variation of ambient temperature. A variational approach is applied to obtain approximate temperature and stress distributions within the plate in a simple analytic form. Stress diagrams derived from the exact temperature distribution are used to assess the accuracy of the method. The method is finally used to determine the magnitude of thermal stresses induced by thermal cycling. The results are shown to be in agreement with those of previous studies. 9 refs.

Barbagelata, A. (D'Appolonia S.p.A., Genoa (Italy))

1989-01-01

288

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

NASA Astrophysics Data System (ADS)

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

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

2011-12-01

289

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

NASA Astrophysics Data System (ADS)

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

Zounemat-Kermani, Mohammad

2012-08-01

290

Non-linear temperature variation of shear viscosity in high- TC superconductors  

NASA Astrophysics Data System (ADS)

The shear viscous flow of high- TC superconductors (HTS) represents a sort of damping mechanism to the flux flow of line lattice. The shear viscosity coefficient of HTS has been investigated for various samples throughout the region 10? T?140 K. The viscosity coefficient increases slowly at low temperatures, then develops a peak around the transition temperature, thereafter decreases rapidly as the temperature increases. An analytic expression for the shear viscosity is found to vary according to the exponential law having the form ( A- T/ TC) -1.24. Higher damping and slower flux motion may produce higher values of the shear viscosity coefficient. This is because higher critical currents may be carried by HTS before it makes transition to the normal state.

Abu-Samreh, Mohammad M.

2002-08-01

291

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

NASA Astrophysics Data System (ADS)

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-2 s-1, 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.

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

2008-10-01

292

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

293

Thrust characteristics of a double-sided high temperature superconducting linear synchronous motor with a high temperature superconducting magnetic suspension system  

NASA Astrophysics Data System (ADS)

An electromagnetic design of a double-sided high temperature superconducting (HTS) linear synchronous motor (HTSLSM) with an HTS bulk magnet secondary is introduced in this paper. A HTS magnetic suspension system is applied to replace the sliding rail to levitate the secondary mover resulting in the HTSLSM moving without sliding friction. The thrust model of the HTSLSM is built using a magnetic circuit method and the thrust characteristics obtained from the model are compared with finite element analysis and practical testing results. The theoretical analysis on the prototype has also been verified by measurements.

Jin, Jianxun; Zheng, Luhai; Xu, Wei; Guo, Youguang; Zhu, Jianguo

2011-04-01

294

Spatial trend patterns of Sea Surface Temperature, 20°C isotherm depth and sea level in the Pacific Ocean during 1993 - 2012  

NASA Astrophysics Data System (ADS)

Analysis and comparison of spatial trend patterns and variability of observed sea level, steric sea level and Sea Surface Temperature (SST) in the Pacific Ocean during the altimetry era (1993-2012) shows that the observed sea level trend patterns in this region result from the superposition of two main signals: (1) a strong broad scale V-shaped positive trend anomaly-extending to mid-latitudes in the central Pacific and (2) another very strong positive trend anomaly located between 120°E and 160° E longitude and ~20°S-20°N latitude (Tropical Pacific). The type (1) signal also observed in SST is characteristic of the Pacific Decadal Oscillation (PDO) and reflects the ocean-atmosphere coupling. The type (2) signal related to El Nino Southern Oscillation (ENSO), is steric in origin and as shown in several previous studies is mostly due to the deepening of the thermocline. In this study, we further show that the depth of the 20°C isotherm (supposed to represent the thermocline) presents a spatial trend pattern highly correlated to that of observed sea level. The computed steric sea level associated with the 20°C isotherm depth (i.e. steric sea level calculated between 0m and 20°C isotherm depth) explains the observed sea level trend very well. The results imply that PDO and ENSO related signals explain most of the observed sea level trend pattern in the Pacific Ocean. A supplementary study on the impact of geostrophic surface currents on sea level change in the Tropical Pacific is also performed.

Palanisamy, H. K.; Cazenave, A. A.; Delcroix, T. C.; Meyssignac, B.

2013-12-01

295

The integrated effects of temperature and stress on the formation of carbon linear atomic chains from graphene nanoribbons  

NASA Astrophysics Data System (ADS)

In situ experiments for graphene nanoribbons (GNRs) under electron beam irradiation show their thinning process. In particular, carbon linear atomic chains (LACs) were observed with high resolution transmission electron microscopy. In order to further understand the structural evolution and breaking mechanisms under stress and a wide range of temperatures that are yet to be fully explored by experiments, we use a molecular dynamics (MD) method to simulate the mechanical properties of GNRs. At high temperatures, our simulations produce non-hexagons and long LACs, whose main features are similar to the experimental results. We show how defects lead to the formation of definitely stable LACs, while at low temperatures, tensile deformation modes become brittle due to localized defects, which are attributed to insufficient thermal energy. In the simulation of zigzag GNRs at high temperatures, we unexpectedly obtained a fracture of the armchair-zigzag bridge connected by non-hexagons. These results offer insights for nanoelectronic device fabrication through a stress-temperature-controlled procedure on GNRs.

Zhu, Jianwei; Shi, Daning

2011-11-01

296

Linear stability of a compressible coaxial jet with continuous velocity and temperature profiles  

NASA Astrophysics Data System (ADS)

This paper describes an investigation of the stability of a jet with velocity and temperature profiles characteristic of the exit region for a turbofan engine. Because the bypass stream mixes with both the exhaust and the ambient air, these profiles contain thin layers in which the velocity and temperature may vary rapidly. As a consequence, multiple instability modes are possible. In accordance with Rayleigh's theorem for axisymmetric incompressible shear flows, it turns out that there are three possible modes, only two of which are unstable. We consider the effect on spatial growth rates of varying the diameter and velocity ratios, compressibility, and azimuthal wavenumber. Radiating modes, that are possible when the primary jet is heated, are also studied.

Perrault-Joncas, Dominique; Maslowe, Sherwin A.

2008-07-01

297

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

298

Calc-alkali rocks derived from tholeiite magma in Hakone volcano; pyroxene crystallization trends and pyroxene geothermometry to estimate the magma temperature  

NASA Astrophysics Data System (ADS)

Calc-alkali rocks are widely distributed in the island arcs. The several models of their magma-genesis were proposed by many geoscientists (e.g. Kuno 1950, Osborn 1959, Sakuyama 1981, Tatsumi 2011) on the bases of precise petrological investigations. Crystallization trends of rock forming minerals (pyroxene, feldspar etc.) in the individual lava flow of the hydrous tholeiitic magma are represented by chemical zoning from phenocryst through microphenocryst to the groundmass in each lava. Those trends indicate degassing (or dehydrating) trends of erupted lava (Ishii 1991). Crystallization trend of minerals of hydrous magma in the subvolcanic magma reservoir is represented by core of phenocrysts throughout lava-flow strata in each volcano. Those trends indicate water-enrichment (or hydrating) trend in the magma reservoir. On the bases of the detailed analyses of the pyroxene crystallization sequences as well as estimated magmatic temperatures using pyroxene geothermometer, for calc-alkali rocks from the Central Cone (CC) in the Hakone volcano, the following working hypothesis is suggested, i.e. those calc-alkali rocks are induced by magma mixing between high temperature (about 1120 Degree Centigrade) tholeiite magma and low temperature (about 970 Degree Centigrade) magma, the latter is originated from fractional crystallization of the primitive high temperature hydras island-arc tholeiite magma within magma reservoir under closed environment for water. Reference Ishii, T., 1991. Lava-flow and subvolcanic magma reservoir composition trends in the Ca-poor pyroxenes of Hakone Volcano, Japan. Jour. Petrol., 32, 429-450 Kuno, H., 1950. Petrology of Hakone volcano and the adjacent areas, Japan. Bull. Geol. Soc. Am., 61, 957-1019. Sakuyama, M., 1981. Petrological study of the Myoko and Kurohime volcanoes, Japan: crystallization sequence and evidence for magma mixing. Jour. Petrol., 22, 553-583. Osborn, E. F., 1959. Role of oxygen pressure in the crystallization and differentiation of basaltic magma. Am. Jour. Sci., 257, 609-647. Tatsumi, Y., 2011. Pigeonitic rock series vs. hypersthenic rock series. Japan Geoscience Union Meeting 2011 abstract SVC052-09

Ishii, T.

2012-12-01

299

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

300

Strong-coupling theory of the universal linear temperature dependence of the nodal Fermi velocity in layered cuprates  

NASA Astrophysics Data System (ADS)

We explain the recently observed linear temperature dependence of the nodal Fermi velocity vF(T) in nearly optimally doped cuprates. We argue that it originates from electron-electron interaction and it is a fundamental property of an arbitrary two-dimensional (2D) Fermi liquid. We consider a spin-fermion model with input parameters extracted from the data, and we show that the T term is about 30% at 300 K, in agreement with the data. We show that the sub-leading term in vF(T) is a regular (and small) T2 correction. We also show that at a 2kF quantum-critical point, temperature corrections to the dispersion are singular.

Chubukov, Andrey; Eremin, Ilya

2008-08-01

301

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

302

Removal of linear alkylbenzene sulfonates and their degradation intermediates at low temperatures during activated sludge treatment.  

PubMed

The degradation of linear alkylbenzene sulfonates and their degradation intermediates (sulfophenylcarboxylic acids) has been characterized at 9 degrees C in an activated sludge pilot plant. After an adequate adaptation period (20 days), LAS primary degradation exceeds 99% and takes place preferentially for long alkyl chain homologues and external isomers. LAS homologues in the reactor are preferentially sorbed onto particulate matter, while sulfophenylcarboxylic acids (SPCs) are present predominantly in solution, due to their lower hydrophobicity. During the adaptation period the most abundant LAS biodegradation intermediates were long chain sulfophenylcarboxylic acids (SPCs) (C(9)-C(13)SPC). However once this system is fully adapted, the microorganisms are capable of degrading SPCs efficiently. SPCs with 7-9 carbon atoms in the carboxylic chain predominate due to their degradation being slower than for the rest of the SPCs. The presence of C(13)SPC confirms that LAS degradation in wastewater starts with a omega-oxidation on the alkylic chain. A preferential degradation of SPC isomers of the types 2phiC(n)SPC to 6phiC(n)SPC was also detected, as shown by the relatively higher SPC concentrations of the remaining ones. PMID:16403553

León, V M; López, C; Lara-Martín, P A; Prats, D; Varó, P; González-Mazo, E

2006-08-01

303

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

304

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

305

The PTI Giant Star Angular Size Survey: Effective Temperatures & Linear Radii  

NASA Astrophysics Data System (ADS)

We report new interferometric angular diameter observations of over 200 giant stars observed with the Palomar Testbed Interferometer (PTI). These angular diameters are combined with bolometric fluxes derived from detailed spectral energy distribution (SED) fits, to produce robust estimates of effective temperature (T_EFF). These SED fits include reddening estimates and are based upon fits of empirical spectral templates to literature photometry, and narrow-band photometry obtained at the Lowell 31" telescope. Over the range from G5III to M8III, T_EFF estimates are precise to 50K per spectral type. Radius estimates are limited by the improved Hipparcos estimates of van Leeuwen (2007) and are typically ~10% per star.

van Belle, Gerard; Ciardi, D. R.; von Braun, K.

2014-01-01

306

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

307

Impact of Temperature Trends on Short-Term Energy Demand, The (Released in the STEO September 1999)  

EIA Publications

The past few years have witnessed unusually warm weather, as evidenced by both mild winters and hot summers. The analysis shows that the 30-year norms--the basis of weather-related energy demand projections--donot reflect the warming trend or its regional and seasonal patterns.

Information Center

1999-09-01

308

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

309

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

310

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

NASA Astrophysics Data System (ADS)

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 (?Bz), perpendicular magnetic flutter (?B?), 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.

2011-10-01

311

11-year Solar Cycle and Long Term Trend in OH airglow Temperature Observations at the South Pole Station, Antarctica  

Microsoft Academic Search

We have examined Michelson Interferometer OH airglow temperature data to investigate solar cycle and long-term variations of mesospheric temperatures at the South Pole Station, Antarctica (90o S). The aforementioned MI has been making observations of temperature and airglow emissions since 1992 during austral winter night. These continuous measurements during the six months of each polar winter allow us to investigate

I. Azeem; G. G. Sivjee; Y. Won; C. Mutiso

2005-01-01

312

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

SciTech Connect

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

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

2010-05-01

313

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

NASA Astrophysics Data System (ADS)

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

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

2009-04-01

314

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

315

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

316

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

317

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

Microsoft Academic Search

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

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

2008-01-01

318

Trend Analysis Using Microcomputers.  

ERIC Educational Resources Information Center

A trend analysis statistical package and additional programs for the Apple microcomputer are presented. They illustrate strategies of data analysis suitable to the graphics and processing capabilities of the microcomputer. The programs analyze data sets using examples of: (1) analysis of variance with multiple linear regression; (2) exponential…

Berger, Carl F.

319

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

Microsoft Academic Search

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

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

2011-01-01

320

A growing 2D spherulite and calculus of variations Part II: A 2D spherulite of polypropylene in a linear temperature field  

Microsoft Academic Search

A 2D spherulite grows in a linear-temperature field from a nucleus of polypropylene at (0,0). The growth lines and the growth fronts are computed by the calculus of variations. The agreement between theory and experiment is satisfactory

G. E. W. Schulze; T. R. Naujeck

1991-01-01

321

Recent trends in winter temperature extremes in eastern China and their relationship with the Arctic Oscillation and ENSO  

NASA Astrophysics Data System (ADS)

Interannual variations in the number of winter extreme warm and cold days over eastern China (EC) and their relationship with the Arctic Oscillation (AO) and El Niño-Southern Oscillation (ENSO) were investigated using an updated temperature dataset comprising 542 Chinese stations during the period 1961-2011. Results showed that the number of winter extreme warm (cold) days across EC experienced a significant increase (decrease) around the mid-1980s, which could be attributed to interdecadal variation of the East Asian Winter Monsoon (EAWM). Probability distribution functions (PDFs) of winter temperature extremes in different phases of the AO and ENSO were estimated based on Generalized Extreme Value Distribution theory. Correlation analysis and the PDF technique consistently demonstrated that interannual variation of winter extreme cold days in the northern part of EC (NEC) is closely linked to the AO, while it is most strongly related to the ENSO in the southern part (SEC). However, the number of winter extreme warm days across EC has little correlation with both AO and ENSO. Furthermore, results indicated that, whether before or after the mid-1980s shift, a significant connection existed between winter extreme cold days in NEC and the AO. However, a significant connection between winter extreme cold days in SEC and the ENSO was only found after the mid-1980s shift. These results highlight the different roles of the AO and ENSO in influencing winter temperature extremes in different parts of EC and in different periods, thus providing important clues for improving short-term climate prediction for winter temperature extremes.

Chen, Shangfeng; Chen, Wen; Wei, Ke

2013-11-01

322

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

323

Application of a novel linear regression analysis to phase-space representations of air and soil temperature relationships  

Microsoft Academic Search

Thermal orbits are phase-space representations of air and soil temperature relationships that are generated by plotting daily or monthly subsurface temperatures against corresponding air temperatures. The resulting illustrations are analogous to Lisajous figures, common in electronic circuit analysis, and have become useful descriptive tools that illustrate perturbations to air and soil temperature relationships in the presence of land- surface processes

J. Smerdon; H. Beltrami; J. Gonzalez-Rouco

2008-01-01

324

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

NASA Astrophysics Data System (ADS)

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

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

2013-06-01

325

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

326

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

327

Enterprise Trends  

ERIC Educational Resources Information Center

Education research experts Eduventures released a report in February 2007 on where U.S. districts are headed with large system management. "Trends in K-12 Enterprise Management: Are Districts Ready to Cross the Chasm?" provides a detailed assessment of the themes and the trends that are driving the market for K-12 enterprise management systems.…

Technology & Learning, 2007

2007-01-01

328

Statistical properties of record-breaking temperatures.  

PubMed

A record-breaking temperature is the highest or lowest temperature at a station since the period of time considered began. The temperatures at a station constitute a time series. After the removal of daily and annual periodicities, the primary considerations are trends (i.e., global warming) and long-range correlations. We first carry out Monte Carlo simulations to determine the influence of trends and long-range correlations on record-breaking statistics. We take a time series that is a Gaussian white noise and give the classic record-breaking theory results for an independent and identically distributed process. We then carry out simulations to determine the influence of long-range correlations and linear temperature trends. For the range of fractional Gaussian noises that are observed to be applicable to temperature time series, the influence on the record-breaking statistics is less than 10%. We next superimpose a linear trend on a Gaussian white noise and extend the theory to include the effect of an additive trend. We determine the ratios of the number of maximum to the number of minimum record-breaking temperatures. We find the single governing parameter to be the ratio of the temperature change per year to the standard deviation of the underlying white noise. To test our approach, we consider a 30 yr record of temperatures at the Mauna Loa Observatory for 1977-2006. We determine the temperature trends by direct measurements and use our simulations to infer trends from the number of record-breaking temperatures. The two approaches give values that are in good agreement. We find that the warming trend is primarily due to an increase in the (overnight) minimum temperatures, while the maximum (daytime) temperatures are approximately constant. PMID:21230709

Newman, William I; Malamud, Bruce D; Turcotte, Donald L

2010-12-01

329

Recent and historical range shifts of two canopy-forming seaweeds in North Spain and the link with trends in sea surface temperature  

NASA Astrophysics Data System (ADS)

Geographical range shifts of two canopy-forming seaweeds, Himanthalia elongata (L.) S.F. Gray and Fucus serratus L. were investigated at their southern range boundary in Northern Spain from the end of nineteenth century to 2009. Given the good dispersal abilities of H. elongata and its short life-span, we hypothesize that this species will track environmental changes at a faster rate than the perennial and short-distance disperser F. serratus. Our results show a continuous and drastic westward retraction of H. elongata, which has nowadays virtually vanished in Northern Spain, whereas F. serratus is still found in the westernmost area. Despite this, the first species is still relatively abundant in the Iberian Peninsula, whereas the presence of the latter is scattered and reduced. Overall, range shifts fit with the warming trend in sea surface temperature (SST), whereas it is unlikely that increases in grazing pressure or coastal pollution have driven the observed changes, particularly the rapid trend in recent years. Differences in species traits are linked to range dynamics. The higher persistence of F. serratus at eastern shores may thus be related to its longer life span and its greater thermal tolerance. The presence of sporadic populations of H. elongata outside the zone of continuous distribution can be attributed to long-distance dispersal events during cold pulses. Relict populations in isolated and estuarine locations were left behind in the contracting range margins, particularly for F. serratus. In Northern Spain, the westward retreat of large canopy-forming algae seems to be a general phenomenon, involving other species such as kelps. Therefore, an evident reorganization of coastal assemblages is expected, though the temporal extent of changes and the consequences for ecosystem services need to be evaluated.

Duarte, Linney; Viejo, Rosa M.; Martínez, Brezo; deCastro, Maite; Gómez-Gesteira, Moncho; Gallardo, Tomás

2013-08-01

330

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

331

CONSTRUCTION AND APPLICATION OF A SCALED-LINEARIZED ARIDITY INDEX BASED ON RAINFALL AND AIR TEMPERATURE DATA  

Microsoft Academic Search

Aridity is a result of the interactions of several parameters, where rainfall and temperature play an important role. In any climate-related analytical process, these parameters are inputs for a decision-making model. When modeling the aridity phenomena, it is often necessary to evaluate the aridity of regions with extreme values of temperature and rainfall. In this work, an aridity model was

E. TROYO-DI; B. MURILLO-AMADOR; R. D. VALDEZ-CEPEDA; J. L. GARCÕA-HERN

332

Temperature dependence of viscoelastic properties of polymers under dynamic conditions on the basis of the linear theory of thermoviscoelasticity  

Microsoft Academic Search

Another method of taking the temperature dependence of the deformation properties of a material into account is based on the use of relationships between the coefficients of the determining equations and the temperature as a parameter [5, 6]. In this case, the temperaturedependence of the inelastic constants is usually studied by conducting long-term creep or relaxation tests [6]. Short-term tests

V. S. Ekel'chik; V. S. Ismailov; S. N. Kostritskii; A. K. Sborovskii

1977-01-01

333

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

334

Relationship Between Anelastic and Non-Linear Visco-Plastic Behavior of 316 Stainless Steel at Low Homologous Temperature.  

National Technical Information Service (NTIS)

At low homologous temperature the plastic strain rate seems to be controlled largely by dislocation glide friction. However, since a sizeable fraction of the applied stress sigma is dissipated in overcoming the strong barriers due to dislocation tangles g...

N. Nir F. H. Huang E. W. Hart C. Y. Li

1976-01-01

335

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

336

Development and experimental verification of a theory for high-field, ultralow-temperature magnetic linear dichroism of glasses containing molecular chromophores with spin doublet ground states  

NASA Astrophysics Data System (ADS)

The first observation of magnetic linear dichroism in a metalloprotein Kramers system is reported, namely, that exhibited by the porphyrin moiety in ferricytochrome c (spin S=12). The measurements were conducted at low temperatures and in strong magnetic fields to maximize the signal intensity, which is intrinsicly weak in this case. The theory used in the interpretation of the wavelength dependence of this magneto-optical effect is based on the rigid-shift approximation in which the dichroic spectra are expressed as a sum of zeroth, first, and second derivatives of the underlying electronic absorption band. Similar to the case for magnetic circular dichroism, magnetic linear dichroism is caused by the Zeeman interactions of the molecular-chromophore electrons with an applied magnetic field. Two kinds of Zeeman interaction are considered, termed ``inner state'' and ``outer state'' depending on, respectively, whether or not they act between the components of a single Kramers doublet of the chromophore. It is formally demonstrated that the zeroth-derivative term for an electric-dipole transition between Kramers doublets arising from inner-state Zeeman interactions (nominally the strongest effect) completely cancels in the powder average over a randomly oriented ensemble of chromophores for all values of temperature and field. This cancellation has a profound effect on the magnetic linear dichroism of molecular chromophores suspended in glasses, as the effect now entirely relies on a set of weaker residual terms, each one having its own spectroscopic characteristics. The residual contributions have been estimated on the basis of electronic-term-energy differences and bandwidths in ferricytochrome c, resulting in the identification of the inner- and outer-state terms C1 and F0 as the dominant signatures. This prediction is in agreement with the experimental data for the shape and dependence on applied field and temperature of the magneto-dichroic spectrum for this chromophore. The magnetic linear dichroisms arising from inner- and outer-state Zeeman interactions in a system with S=12, like the one considered here, are of comparable magnitude, which makes the information content of magnetic linear dichroism distinctly different from that obtainable from magnetic circular dichroism, where the inner-state contributions dominate. From this analysis, magnetic linear dichroism emerges as the preferred magneto-optical spectroscopy for assessing outer-state Zeeman interactions under cryogenic conditions and is, in this respect, complementary to magnetic circular dichroism.

Bominaar, Emile L.; Peterson, Jim

1999-10-01

337

Earthworm effects on the use of C sources by microorganisms: Non-linear response to temperature alteration  

Microsoft Academic Search

A microcosm was used to study the effect of the endogeic earthworm Aporrectodea caliginosa (Savigny) on the use of C by microorganisms in a calcareous beech forest soil and its dependence on temperature (5–25%C). Inclusion of 14C-labelled beech leaf litter made it possible to differentiate between C use by litter-colonizing microflora and by autochthonous soil microflora. The effect of temperature

Volkmar Wolters; Klemens Ekschmitt

1995-01-01

338

Towards a robust test on North America warming trend and precipitable water content increase  

Microsoft Academic Search

An increase in the atmospheric moist content has been generally assumed when the lower-tropospheric temperature (Tcol) increases, with relative humidity holding steady. Rather than using simple linear regression, we propose a more rigorous trend detection method that considers time series memory. The autoregressive moving-average (ARMA) parameters for the time series of Tcol, precipitable water vapor (PWAV), and total precipitable water

Jih-Wang Wang; Ke Wang; Roger A. Pielke; John C. Lin; Toshihisa Matsui

2008-01-01

339

Linear temperature dependence of resistivity and change in the Fermi surface at the pseudogap critical point of a high-Tc superconductor  

NASA Astrophysics Data System (ADS)

A fundamental question for high-temperature superconductors is the nature of the pseudogap phase, which lies between the Mott insulator at zero doping and the Fermi liquid at high doping p (refs 1, 2). Here we report on the behaviour of charge carriers near the zero-temperature onset of this phase, namely at the critical doping p*, where the pseudogap temperature T* goes to zero, accessed by investigating a material in which superconductivity can be fully suppressed by a steady magnetic field. Just below p*, the normal-state resistivity and Hall coefficient of La1.6-xNd0.4SrxCuO4 are found to rise simultaneously as the temperature drops below T*, suggesting a change in the Fermi surface with a large associated drop in conductivity. At p*, the resistivity shows a linear temperature dependence as the temperature approaches zero, a typical signature of a quantum critical point. These findings impose new constraints on the mechanisms responsible for inelastic scattering and Fermi-surface transformation in theories of the pseudogap phase.

Daou, R.; Doiron-Leyraud, Nicolas; Leboeuf, David; Li, S. Y.; Laliberté, Francis; Cyr-Choinière, Olivier; Jo, Y. J.; Balicas, L.; Yan, J.-Q.; Zhou, J.-S.; Goodenough, J. B.; Taillefer, Louis

2009-01-01

340

Non-linear temperature oscillations in the plasma centre on Tore Supra and their interplay with MHD  

Microsoft Academic Search

Regular oscillations of the central electron temperature have been observed by means of ECE and SXR diagnostics during non-inductively driven discharges on Tore Supra. These oscillations are sustained by LHCD, do not have a helical structure and, therefore, cannot be ascribed as MHD phenomena. The most probable explanation of this oscillating regime (O-regime) is the assumption that the plasma current

V. S. Udintsev; G. Giruzzi; F. Imbeaux; J.-F. Artaud; X. Garbet; G. Huysmans; P. Maget; J.-L. Segui; A. Becoulet; G. T. Hoang; E. Joffrin; X. Litaudon; B. Saoutic

2004-01-01

341

Ultra Linear Dual-band WLAN Front-End Module for 802.11 a\\/b\\/g\\/n Applications with Wide Voltage and Temperature Range Operation  

Microsoft Academic Search

A compact 7 times 8 times 1.1 mm3 dual-band Wireless LAN front-end module (FEM) having high linearity and wide temperature (-40 to 85degC) and voltage (2.7 to 4.5 V) operating ranges is presented. The FEM features 28 dB gain and 19.8 dBm at 54 Mbps with EVM < 3% and 230 mA for 2.4 to 2.5 GHz. For 4.9 to

C.-W. P. Huang; Christophe Masse; Chris Zelley; Craig Christmas; T. Whittaker; J. Soricelli; W. Vaillancourt; A. Parolin

2007-01-01

342

Magnetic susceptibility and low-temperature structure of the linear chain cuprate Sr2CuO3  

NASA Astrophysics Data System (ADS)

Magnetic susceptibility measurements for Sr2CuO3+/-? were made from 2 to 800 K, and a strong dependence upon oxygen content (?) was observed. Samples synthesized under oxygen, followed by various nitrogen treatments, exhibited markedly different Curie-Weiss-type terms, and we discuss possible origins for this behavior. High-temperature magnetic susceptibility measurements for the sample with the smallest Curie-Weiss-type term clearly show the increase with temperature expected from the Bonner-Fisher model for a spin-1/2 one-dimensional (1D) Heisenberg antiferromagnet. This is a direct experimental observation of 1D magnetic behavior in this system. The in-chain superexchange coupling constant, as determined by a fit to the Bonner-Fisher model, is ||J||/kB~=1300+100-200 K, comparable to the values observed in the two-dimensional layered cuprates. Estimates of the interchain magnetic interaction indicate this material may be the best realization of a 1D spin-1/2 Heisenberg antiferromagnet reported to date. Low-temperature neutron and synchrotron x-ray powder-diffraction studies of Sr2CuO3 show that the low-temperature structure of this system has Immm space-group symmetry, the same structure reported at room temperature, indicating that this material, in contrast to La2CuO4, does not undergo any structural transformations upon cooling. The absence of crystallographic distortions precludes a magnetic anisotropy contribution from a Dzyaloshinsky-Moriya interaction, implying that Sr2CuO3 should be a nearly ideal spin-1/2 antiferromagnetic Heisenberg chain compound, in agreement with the magnetic susceptibility results. A search for the presence of long-range three-dimensional antiferromagnetic order by magnetic neutron powder diffraction at temperatures as low as 1.5 K was not successful, although we estimate an upper limit for the size of the ordered moment which could have been detected to be ~0.1?B per Cu2+ ion.

Ami, T.; Crawford, M. K.; Harlow, R. L.; Wang, Z. R.; Johnston, D. C.; Huang, Q.; Erwin, R. W.

1995-03-01

343

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.

344

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

345

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.

346

Global Trends.  

National Technical Information Service (NTIS)

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 atm...

G. Megie M. Chanin D. Ehhalt P. Fraser J. F. Frederick

1990-01-01

347

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

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

348

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

NASA Astrophysics Data System (ADS)

The effect of cross-linking of blends on the stability of positive temperature coefficient (PTC) and the elimination of negative temperature coefficient (NTC) were investigated. Linear low density polyethylene (LLDPE) was chemically cross-linking with various amounts of dicumyl peroxide (DCP). The resulting of cross-linking structure of composites was analyzed by gel content, differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA). By the effect of DCP, not only a high PTC intensity appeared, but also was the NTC effect of the composite eliminated. The PTC intensity reached six orders of magnitude for the LLDPE/DCP(0.10 wt%)/CB/Al(OH)3 composite, and successfully passed the test of over-voltage resistance.

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

2008-08-01

349

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

350

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

351

Generation of ultrahigh peak capacity LC separations via elevated temperatures and high linear mobile-phase velocities.  

PubMed

The use of a combination of ultraperformance liquid chromatography at approximately 11,000 psi on sub 2-microm particles combined with reversed-phase gradient chromatography at a temperature of 90 degrees C is described as applied to the analysis of endogenous and drug metabolites in human and animal urine. By using elevated temperatures, back pressures can be reduced while maintaining high flow rates and chromatographic efficiency, with peaks 1-3 s wide at the base. Application to urine samples provided a peak capacity of approximately 700 for a 10-min analysis and greater than approximately 1000 in 1 h. Despite the narrow nature of the peaks, good quality mass spectra were also obtained, allowing the identification of typical drug and endogenous metabolites. These ultra-high-resolution chromatograms should be ideal for the analysis of complex samples in, for example, metabolite identification, impurity identification, and metabonomic/metabolomic studies. Applications in natural product analysis and proteomics can also be envisaged. PMID:17037933

Plumb, Robert S; Rainville, Paul; Smith, Brian W; Johnson, Kelly A; Castro-Perez, Jose; Wilson, Ian D; Nicholson, Jeremy K

2006-10-15

352

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

353

Dynamics of Nonlinear Coupling between Electron-Temperature-Gradient Mode and Drift-Wave Mode in Linear Magnetized Plasmas  

NASA Astrophysics Data System (ADS)

A high-frequency (˜0.4MHz) fluctuation is excited by an electron temperature gradient (ETG) perpendicular to magnetic field lines, which is consistent with an ETG mode. When the fluctuation amplitude of the ETG mode exceeds a certain threshold, the mode gradually becomes saturated and a low-frequency (˜7kHz) fluctuation which is originally caused by a drift wave is enhanced, corresponding to the saturation of the ETG mode. In addition, a nonlinear coupling, specifically, the bicoherence between the ETG mode and the drift wave mode, begins to increase when the ETG strength exceeds the threshold, which simultaneously occurs with the saturation of the ETG mode. Thus, it was determined that the ETG mode stimulates the drift wave mode excitement via multiscale nonlinear interaction between the high-frequency (˜MHz) and low-frequency (˜kHz) fluctuations, which ultimately causes ETG mode energy to be transferred to the drift wave mode.

Moon, Chanho; Kaneko, Toshiro; Hatakeyama, Rikizo

2013-09-01

354

Dynamics of nonlinear coupling between electron-temperature-gradient mode and drift-wave mode in linear magnetized plasmas.  

PubMed

A high-frequency (?0.4??MHz) fluctuation is excited by an electron temperature gradient (ETG) perpendicular to magnetic field lines, which is consistent with an ETG mode. When the fluctuation amplitude of the ETG mode exceeds a certain threshold, the mode gradually becomes saturated and a low-frequency (?7??kHz) fluctuation which is originally caused by a drift wave is enhanced, corresponding to the saturation of the ETG mode. In addition, a nonlinear coupling, specifically, the bicoherence between the ETG mode and the drift wave mode, begins to increase when the ETG strength exceeds the threshold, which simultaneously occurs with the saturation of the ETG mode. Thus, it was determined that the ETG mode stimulates the drift wave mode excitement via multiscale nonlinear interaction between the high-frequency (?MHz) and low-frequency (?kHz) fluctuations, which ultimately causes ETG mode energy to be transferred to the drift wave mode. PMID:24074096

Moon, Chanho; Kaneko, Toshiro; Hatakeyama, Rikizo

2013-09-13

355

How much have variations in the meridional overturning circulation contributed to sea surface temperature trends since 1850? A study with the EC-Earth global climate model  

NASA Astrophysics Data System (ADS)

The surface of the worlds' oceans has been warming since the beginning of industrialisation mainly due to larger atmospheric greenhouse gas concentrations. In addition to that multidecadal SST variations of internal origin exist. Evidence points to the North Atlantic Ocean as exhibiting the strongest multidecadal SST variations and that these variations are connected to the overturning circulation. In this work we investigate the extent to which these internal multidecadal variations have contributed to enhancing or diminishing the trend induced by the external radiative forcing globally and in the North Atlantic. We do so in a model study where we combine the analysis of a long control simulation with constant forcing corresponding to preindustrial conditions and an ensemble of simulations with historical forcing from 1850 until 2005. First we note that global SST trends calculated from the different historical simulations are similar, while there is a large disagreement between the North Atlantic SST trends. Then we analyse the control simulation, where we identify a relationship between SST anomalies and anomalies in the Atlantic Meridional Overturning Circulation (AMOC) for multidecadal and longer time scales. This relationship enables us to extract the AMOC-related SST variability from each individual member of the ensemble of historical simulations and then to calculate the SST trends with the AMOC-related variability excluded. For the global SST trends this causes only a little difference while SST trends with AMOC related variability excluded for the North Atlantic show closer agreement than with the AMOC-related variability included. From this we conclude that AMOC variability contributed significantly to North Atlantic SST trends since the mid 19th century.

Schmith, Torben; Yang, Shuting; Gleeson, Emily; Semmler, Tido

2014-05-01

356

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

357

Linear and nonlinear propagation of ion-acoustic waves in a multi-ion plasma with positrons and two-temperature superthermal electrons  

NASA Astrophysics Data System (ADS)

Linear and fully nonlinear features of ion-acoustic waves (IAWs) have been investigated by normal mode analysis (which is valid for extremely small amplitude limit) and pseudopotential approach (which is valid for arbitrary amplitude waves). The plasma is assumed to be composed of nonthermally ? (kappa)-distributed two-temperature electrons (termed as hot and cold), Maxwellian positrons, inertial ions and immobile negatively charged heavy ions. The pseudo-energy balance equation is derived from the fluid dynamical system of equations, and the properties of arbitrary amplitude ion-acoustic wave (IAW) excitations are examined. The basic features (width, amplitude, polarity, critical Mach number, speed, etc.) of IAWs are found to be significantly modified by the effects of positrons, heavy ions as well as by the effects of ?-distributed two-temperature superthermal electrons. The analytical and numerical results presented in this manuscript could be useful for explaining and understanding the basic features of solitary structures in astrophysical environments, where two-temperature superthermal electrons and thermal positrons exist.

Sultana, S.; Mamun, A. A.

2014-01-01

358

Contrails, Cirrus Trends, and Climate  

Microsoft Academic Search

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

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

2004-01-01

359

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

360

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

361

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

362

Characterizing the effect of temperature fluctuation on the incidence of malaria: an epidemiological study in south-west China using the varying coefficient distributed lag non-linear model  

PubMed Central

Background Malaria transmission is strongly determined by the environmental temperature and the environment is rarely constant. Therefore, mosquitoes and parasites are not only exposed to the mean temperature, but also to daily temperature variation. Recently, both theoretical and laboratory work has shown, in addition to mean temperatures, daily fluctuations in temperature can affect essential mosquito and parasite traits that determine malaria transmission intensity. However, so far there is no epidemiological evidence at the population level to this problem. Methods Thirty counties in southwest China were selected, and corresponding weekly malaria cases and weekly meteorological variables were collected from 2004 to 2009. Particularly, maximum, mean and minimum temperatures were collected. The daily temperature fluctuation was measured by the diurnal temperature range (DTR), the difference between the maximum and minimum temperature. The distributed lag non-linear model (MDLNM) was used to study the correlation between weekly malaria incidences and weekly mean temperatures, and the correlation pattern was allowed to vary over different levels of daily temperature fluctuations. Results The overall non-linear patterns for mean temperatures are distinct across different levels of DTR. When under cooler temperature conditions, the larger mean temperature effect on malaria incidences is found in the groups of higher DTR, suggesting that large daily temperature fluctuations act to speed up the malaria incidence in cooler environmental conditions. In contrast, high daily fluctuations under warmer conditions will lead to slow down the mean temperature effect. Furthermore, in the group of highest DTR, 24-25°C or 21-23°C are detected as the optimal temperature for the malaria transmission. Conclusion The environment is rarely constant, and the result highlights the need to consider temperature fluctuations as well as mean temperatures, when trying to understand or predict malaria transmission. This work may be the first epidemiological study confirming that the effect of the mean temperature depends on temperature fluctuations, resulting in relevant evidence at the population level.

2014-01-01

363

Temperature  

NSDL National Science Digital Library

Thermometers record the temperature in a given location. Temperature is a non-living thing because it doesn't physically move or eat, for example. However, temperature is a very important factor that effects where animals live and how long they stay in that particular spot.

Luis Miguel Orta Rial (None;)

2008-03-24

364

Effect of temperature on the low-linear energy transfer radiolysis of the ceric-cerous sulfate dosimeter: a monte carlo simulation study.  

PubMed

The stochastic modeling of the (60)Co ?/fast-electron radiolysis of the ceric-cerous chemical dosimeter has been performed as a function of temperature from 25-350°C. The system used is a dilute solution of ceric sulfate and cerous sulfate in aqueous 0.4 M sulfuric acid. In this system, H(•) (or HO2(•) in the presence of dissolved oxygen) and H2O2 produced by the radiolytic decomposition of water both reduce Ce(4+) ions to Ce(3+) ions, while (•)OH radicals oxidize the Ce(3+) present in the solution back to Ce(4+). The net Ce(3+) yield is given by G(Ce(3+)) = g(H(•)) + 2 g(H2O2) - g((•)OH), where the primary (or "escape") yields of H(•), H2O2 and (•)OH are represented by lower case g's. At room temperature, G(Ce(3+)) has been established to be 2.44 ± 0.8 molecules/100 eV. In this work, we investigated the effect of temperature on the yield of Ce(3+) and on the underlying chemical reaction kinetics using Monte Carlo track chemistry simulations. The simulations showed that G(Ce(3+)) is time dependent, a result of the differences in the lifetimes of the reactions that make up the radiolysis mechanism. Calculated G(Ce(3+)) values were found to decrease almost linearly with increasing temperature up to about 250°C, and are in excellent agreement with available experimental data. In particular, our calculations confirmed previous estimated values by Katsumura et al. (Radiat Phys Chem 1988; 32:259-63) showing that G(Ce(3+)) at ?250°C is about one third of its value at room temperature. Above ?250°C, our model predicted that G(Ce(3+)) would drop markedly with temperature until, instead of Ce(4+) reduction, Ce(3+) oxidation is observed. This drop is shown to occur as a result of the reaction of hydrogen atoms with water in the homogeneous chemical stage. PMID:24754561

Kohan, Leila Mirsaleh; Meesungnoen, Jintana; Sanguanmith, Sunuchakan; Meesat, Ridthee; Jay-Gerin, Jean-Paul

2014-05-01

365

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

366

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

Microsoft Academic Search

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

Rixt de Jong; Christian Kamenik; Martin Grosjean

2010-01-01

367

Exploring Linear Data  

NSDL National Science Digital Library

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

2009-01-01

368

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.

2002-01-01

369

Spring temperature change and its implication in the change of vegetation growth in North America from 1982 to 2006  

PubMed Central

Understanding how vegetation growth responds to climate change is a critical requirement for projecting future ecosystem dynamics. Parts of North America (NA) have experienced a spring cooling trend over the last three decades, but little is known about the response of vegetation growth to this change. Using observed climate data and satellite-derived Normalized Difference Vegetation Index (NDVI) data from 1982 to 2006, we investigated changes in spring (April–May) temperature trends and their impact on vegetation growth in NA. A piecewise linear regression approach shows that the trend in spring temperature is not continuous through the 25-year period. In the northwestern region of NA, spring temperature increased until the late 1980s or early 1990s, and stalled or decreased afterwards. In response, a spring vegetation greening trend, which was evident in this region during the 1980s, stalled or reversed recently. Conversely, an opposite phenomenon occurred in the northeastern region of NA due to different spring temperature trends. Additionally, the trends of summer vegetation growth vary between the periods before and after the turning point (TP) of spring temperature trends. This change cannot be fully explained by summer drought stress change alone and is partly explained by changes in the trends of spring temperature as well as those of summer temperature. As reported in previous studies, summer vegetation browning trends have occurred in the northwestern region of NA since the early 1990s, which is consistent with the spring and summer cooling trends in this region during this period.

Wang, Xuhui; Piao, Shilong; Ciais, Philippe; Li, Junsheng; Friedlingstein, Pierre; Koven, Charlie; Chen, Anping

2011-01-01

370

Linear and nonlinear optical absorption coefficients and refractive index changes of a spherical quantum dot placed at the center of a cylindrical nano-wire: Effects of hydrostatic pressure and temperature  

NASA Astrophysics Data System (ADS)

The combined effects of hydrostatic pressure and temperature on the optical absorption coefficients and refractive index changes of an InAs spherical quantum dot which is located at the center of a GaAs cylindrical nano-wire have been investigated. The wave functions and corresponding eigenvalues are calculated using finite element method in the framework of effective mass approximation. Analytical expressions for the linear and third order nonlinear optical absorption coefficients and refractive index changes are obtained by means of the compact-density matrix formalism. The linear and third order nonlinear absorption coefficient and refractive index changes are presented as a function of the photon energy, dot radius, pressure, temperature, incident photon intensity and relaxation time. It is found from our calculations that the linear and third order nonlinear optical absorption coefficients, refractive index changes and resonance energy are quite sensitive to the dot size, applied hydrostatic pressure and temperature.

Akbarnavaz Farkoush, B.; Safarpour, Gh.; Zamani, A.

2013-07-01

371

The 20th century cooling trend over the southeastern United States  

NASA Astrophysics Data System (ADS)

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

Rogers, Jeffrey C.

2013-01-01

372

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

NASA Astrophysics Data System (ADS)

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

Saberian, E.; Esfandyari-Kalejahi, A.; Rastkar-Ebrahimzadeh, A.; Afsari-Ghazi, M.

2013-03-01

373

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

SciTech Connect

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

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