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Sample records for linear temperature trends

  1. Coastal ocean climatology of temperature and salinity off the Southern California Bight: Seasonal variability, climate index correlation, and linear trend

    NASA Astrophysics Data System (ADS)

    Kim, Sung Yong; Cornuelle, Bruce D.

    2015-11-01

    A coastal ocean climatology of temperature and salinity in the Southern California Bight is estimated from conductivity-temperature-depth (CTD) and bottle sample profiles collected by historical California Cooperative Oceanic Fisheries Investigation (CalCOFI) cruises (1950-2009; quarterly after 1984) off southern California and quarterly/monthly nearshore CTD surveys (within 30 km from the coast except for the surfzone; 1999-2009) off San Diego and Los Angeles. As these fields are sampled regularly in space, but not in time, conventional Fourier analysis may not be possible. The time dependent temperature and salinity fields are modeled as linear combinations of an annual cycle and its five harmonics, as well as three standard climate indices (El Niňo-Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), North Pacific Gyre Oscillation (NPGO)), the Scripps Pier temperature time series, and a mean and linear trend without time lags. Since several of the predictor indices are correlated, the indices are successively orthogonalized to eliminate ambiguity in the identification of the contributed variance of each component. Regression coefficients are displayed in both vertical transects and horizontal maps to evaluate (1) whether the temporal and spatial scales of the two data sets of nearshore and offshore observations are consistent and (2) how oceanic variability at a regional scale is related to variability in the nearshore waters. The data-derived climatology can be used to identify anomalous events and atypical behaviors in regional-scale oceanic variability and to provide background ocean estimates for mapping or modeling.

  2. Water vapor-weighted mean temperature and its impact on the determination of precipitable water vapor and its linear trend

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoming; Zhang, Kefei; Wu, Suqin; Fan, Shijie; Cheng, Yingyan

    2016-01-01

    Water vapor-weighted mean temperature, Tm, is a vital parameter for retrieving precipitable water vapor (PWV) from the zenith wet delay (ZWD) of Global Navigation Satellite Systems (GNSS) signal propagation. In this study, the Tm at 368 GNSS stations for 2000-2012 were calculated using three methods: (1) temperature and humidity profiles from ERA-Interim, (2) the Bevis Tm-Ts relationship, and (3) the Global Pressure and Temperature 2 wet model. Tm derived from the first method was used as a reference to assess the errors of the other two methods. Comparisons show that the relative errors of the Tm derived from these two methods are in the range of 1-3% across more than 95% of all the stations. The PWVs were calculated using the aforementioned three types of Tm and the GNSS-derived ZWD at 107 stations. Again, the PWVs calculated using Tm from the first method were used as the reference of the other two PWVs. The root-mean-square errors of these two PWVs are both in the range of 0.1-0.7 mm. The second method is recommended in real-time applications, since its performance is slightly better than the third method. In addition, the linear trends of the PWV time series from the first method were also used as the reference to evaluate the trends from the other two methods. Results show that 13% and 23% of the PWV trends from the respective second and third methods have a relative error of larger than 10%. For climate change studies, the first method, if available, is always recommended.

  3. Trends in stratospheric temperature

    NASA Technical Reports Server (NTRS)

    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

    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.

  4. Ozone and temperature trends

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  5. Temperature trend biases

    NASA Astrophysics Data System (ADS)

    Venema, Victor; Lindau, Ralf

    2016-04-01

    In an accompanying talk we show that well-homogenized national dataset warm more than temperatures from global collections averaged over the region of common coverage. In this poster we want to present auxiliary work about possible biases in the raw observations and on how well relative statistical homogenization can remove trend biases. There are several possible causes of cooling biases, which have not been studied much. Siting could be an important factor. Urban stations tend to move away from the centre to better locations. Many stations started inside of urban areas and are nowadays more outside. Even for villages the temperature difference between the centre and edge can be 0.5°C. When a city station moves to an airport, which often happened around WWII, this takes the station (largely) out of the urban heat island. During the 20th century the Stevenson screen was established as the dominant thermometer screen. This screen protected the thermometer much better against radiation than earlier designs. Deficits of earlier measurement methods have artificially warmed the temperatures in the 19th century. Newer studies suggest we may have underestimated the size of this bias. Currently we are in a transition to Automatic Weather Stations. The net global effect of this transition is not clear at this moment. Irrigation on average decreases the 2m-temperature by about 1 degree centigrade. At the same time, irrigation has increased significantly during the last century. People preferentially live in irrigated areas and weather stations serve agriculture. Thus it is possible that there is a higher likelihood that weather stations are erected in irrigated areas than elsewhere. In this case irrigation could lead to a spurious cooling trend. In the Parallel Observations Science Team of the International Surface Temperature Initiative (ISTI-POST) we are studying influence of the introduction of Stevenson screens and Automatic Weather Stations using parallel measurements

  6. Temperature Trends in Montane Lakes

    NASA Astrophysics Data System (ADS)

    Melack, J. M.; Sadro, S.; Jellison, R.

    2014-12-01

    Long-term temperature trends in lakes integrate hydrological and meteorological factors. We examine temperature trends in a small montane lake with prolonged ice-cover and large seasonal snowfall and in a large saline lake. Emerald Lake, located in the Sierra Nevada (California), is representative of high-elevation lakes throughout the region. No significant trend in outflow temperature was apparent from 1991to 2012. Snowfall in the watershed accounted for 93% of the variability in average summer lake temperatures. Mono Lake (California) lies in a closed, montane basin and is hypersaline and monomictic or meromictic. Temperature profiles have been collected from 1982 to 2010. In the upper water column, the July-August-September water temperatures increased 0.8-1.0°C over the 29 years. This rate of warming is less than published estimates based on satellite-derived skin temperatures and will discussed in the context of general limnological interpretation of temperature trends.

  7. Ozone and temperature trends

    NASA Technical Reports Server (NTRS)

    Labitzke, K.; Miller, A. J.; Angell, J.; Deluisi, J.; Frederick, J.; Logan, J.; Mateer, C.; Naujokat, B.; Reinsel, G.; Tiao, G.

    1985-01-01

    The measurement of temporal changes in ozone and temperature are discussed. The data are examined within the context of natural atmospheric variability and data problems. The results are compared to numerical model calculations. The major issues are defined in terms of goal achievement. Each parameter is considered in terms of instrument type, long term effects, and altitude.

  8. Temperature trends in the midlatitude summer mesosphere

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  9. Temperature trends in the mesosphere

    NASA Astrophysics Data System (ADS)

    Lübken, Franz-Josef; Berger, Uwe

    2013-04-01

    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

  10. Estimating population trends with a linear model

    USGS Publications Warehouse

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

    2003-01-01

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

  11. Recent Inland Water Temperature Trends

    NASA Astrophysics Data System (ADS)

    Hook, Simon; Healey, Nathan; Lenters, John; O'Reilly, Catherine

    2016-04-01

    We are using thermal infrared satellite data in conjunction with in situ measurements to produce water temperatures for all the large inland water bodies in North America and the rest of the world for potential use as climate indicator. Recent studies have revealed significant warming of inland waters throughout the world. The observed rate of warming is - in many cases - greater than that of the ambient air temperature. These rapid, unprecedented changes in inland water temperatures have profound implications for lake hydrodynamics, productivity, and biotic communities. Scientists are just beginning to understand the global extent, regional patterns, physical mechanisms, and ecological consequences of lake warming. As part of our work we have collected thermal infrared satellite data from those satellite sensors that provide long-term and frequent spaceborne thermal infrared measurements of inland waters including ATSR, AVHRR, and MODIS and used these to examine trends in water surface temperature for approximately 169 of the largest inland water bodies in the world. We are now extending this work to generate temperature time-series of all North American inland water bodies that are sufficiently large to be studied using 1km resolution satellite data for the last 3 decades, approximately 268 lakes. These data are then being related to changes in the surface air temperature and compared with regional trends in water surface temperature derived from CMIP5/IPCC model simulations/projections to better predict future temperature changes. We will discuss the available datasets and processing methodologies together with the patterns they reveal based on recent changes in the global warming, with a particular focus on the inland waters of the southwestern USA.

  12. Testing for deterministic trends in global sea surface temperature

    NASA Astrophysics Data System (ADS)

    Barbosa, Susana

    2010-05-01

    The identification and estimation of trends is a frequent and fundamental task in the analysis of hydrometeorological records. The task is challenging because even time series generated by purely random processes can exhibit visually appealing trends that can be misleadingly taken as evidence of non-stationary behavior. Hydrometeorological time series exhibiting long range dependence can also exhibit trend-like features that can be mistakenly interpreted as a trend, leading to erroneous forecasts and interpretations of the variability structure of the series, particularly in terms of statistical uncertainty. In practice the overwhelming majority of trends in hydro-climatic records are reported as the slope from a linear regression model. It is therefore important to assess when a linear regression model is a reasonable description for a time series. One could think that if a derived slope is statistically significant, particularly if inference is performed carefully, the linear regression model would be appropriate. However, stochastic features, such as long-range dependence can produce statistically significant linear trends. Therefore, the plausibility of the linear regression model needs to be tested itself, in addition to testing if the trend slope is statistically significant. In this work parametric statistical tests are applied in order to evaluate the trend-stationary assumption in global sea surface temperature for the period from January 1900 to December 2008. The fit of a linear deterministic model to the spatially-averaged global mean SST series yields a statistically significant positive slope, suggesting an increasing linear trend. However, statistical testing rejects the hypothesis of a deterministic linear trend with a stationary stochastic noise. This is supported by the form of the temporal structure of the detrended series, which exhibits large positive values up to lags of 5 years, indicating temporal persistence.

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

    NASA Astrophysics Data System (ADS)

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

    2000-03-01

    This paper examines trend uncertainties in layer-average free atmosphere temperatures arising from the use of different trend estimation methods. It also considers statistical issues that arise in assessing the significance of individual trends and of trend differences between data sets. Possible causes of these trends are not addressed. We use data from satellite and radiosonde measurements and from two reanalysis projects. To facilitate intercomparison, we compute from reanalyses and radiosonde data temperatures equivalent to those from the satellite-based Microwave Sounding Unit (MSU). We compare linear trends based on minimization of absolute deviations (LA) and minimization of squared deviations (LS). Differences are generally less than 0.05°C/decade over 1959-1996. Over 1979-1993, they exceed 0.10°C/decade for lower tropospheric time series and 0.15°C/decade for the lower stratosphere. Trend fitting by the LA method can degrade the lower-tropospheric trend agreement of 0.03°C/decade (over 1979-1996) previously reported for the MSU and radiosonde data. In assessing trend significance we employ two methods to account for temporal autocorrelation effects. With our preferred method, virtually none of the individual 1979-1993 trends in deep-layer temperatures are significantly different from zero. To examine trend differences between data sets we compute 95% confidence intervals for individual trends and show that these overlap for almost all data sets considered. Confidence intervals for lower-tropospheric trends encompass both zero and the model-projected trends due to anthropogenic effects. We also test the significance of a trend in d(t), the time series of differences between a pair of data sets. Use of d(t) removes variability common to both time series and facilitates identification of small trend differences. This more discerning test reveals that roughly 30% of the data set comparisons have significant differences in lower-tropospheric trends

  14. Linearization of Pt resistance temperature measurement circuit

    NASA Astrophysics Data System (ADS)

    Li, Chuan-xiang

    2001-09-01

    A correction method for non-linear Pt resistance temperature measurement based on the principle of A/D conversion is introduced. The design principle of Pt resistance linear temperature measurement is analyzed and a new method for interfacing A/D converter with single chip computer 89c52 is provided together with the experimental data.

  15. The Uncertainty of Long-term Linear Trend in Global SST Due to Internal Variation

    NASA Astrophysics Data System (ADS)

    Lian, Tao

    2016-04-01

    In most parts of the global ocean, the magnitude of the long-term linear trend in sea surface temperature (SST) is much smaller than the amplitude of local multi-scale internal variation. One can thus use the record of a specified period to arbitrarily determine the value and the sign of the long-term linear trend in regional SST, and further leading to controversial conclusions on how global SST responds to global warming in the recent history. Analyzing the linear trend coefficient estimated by the ordinary least-square method indicates that the linear trend consists of two parts: One related to the long-term change, and the other related to the multi-scale internal variation. The sign of the long-term change can be correctly reproduced only when the magnitude of the linear trend coefficient is greater than a theoretical threshold which scales the influence from the multi-scale internal variation. Otherwise, the sign of the linear trend coefficient will depend on the phase of the internal variation, or in the other words, the period being used. An improved least-square method is then proposed to reduce the theoretical threshold. When apply the new method to a global SST reconstruction from 1881 to 2013, we find that in a large part of Pacific, the southern Indian Ocean and North Atlantic, the influence from the multi-scale internal variation on the sign of the linear trend coefficient can-not be excluded. Therefore, the resulting warming or/and cooling linear trends in these regions can-not be fully assigned to global warming.

  16. Trends in Surface Temperature from AIRS.

    NASA Astrophysics Data System (ADS)

    Ruzmaikin, A.; Aumann, H. H.

    2014-12-01

    To address possible causes of the current hiatus in the Earth's global temperature we investigate the trends and variability in the surface temperature using retrievals obtained from the measurements by the Atmospheric Infrared Sounder (AIRS) and its companion instrument, the Advanced Microwave Sounding Unit (AMSU), onboard of Aqua spacecraft in 2002-2014. The data used are L3 monthly means on a 1x1degree spatial grid. We separate the land and ocean temperatures, as well as temperatures in Artic, Antarctic and desert regions. We find a monotonic positive trend for the land temperature but not for the ocean temperature. The difference in the regional trends can help to explain why the global surface temperature remains almost unchanged but the frequency of occurrence of the extreme events increases under rising anthropogenic forcing. The results are compared with the model studies. This work was supported by the Jet Propulsion Laboratory of the California Institute of Technology, under a contract with the National Aeronautics and Space Administration.

  17. The mystery of recent stratospheric temperature trends.

    PubMed

    Thompson, David W J; Seidel, Dian J; Randel, William J; Zou, Cheng-Zhi; Butler, Amy H; Mears, Carl; Osso, Albert; Long, Craig; Lin, Roger

    2012-11-29

    A new data set of middle- and upper-stratospheric temperatures based on reprocessing of satellite radiances provides a view of stratospheric climate change during the period 1979-2005 that is strikingly different from that provided by earlier data sets. The new data call into question our understanding of observed stratospheric temperature trends and our ability to test simulations of the stratospheric response to emissions of greenhouse gases and ozone-depleting substances. Here we highlight the important issues raised by the new data and suggest how the climate science community can resolve them. PMID:23192146

  18. Twentieth-Century Sea Surface Temperature Trends

    PubMed

    Cane; Clement; Kaplan; Kushnir; Pozdnyakov; Seager; Zebiak; Murtugudde

    1997-02-14

    An analysis of historical sea surface temperatures provides evidence for global warming since 1900, in line with land-based analyses of global temperature trends, and also shows that over the same period, the eastern equatorial Pacific cooled and the zonal sea surface temperature gradient strengthened. Recent theoretical studies have predicted such a pattern as a response of the coupled ocean-atmosphere system to an exogenous heating of the tropical atmosphere. This pattern, however, is not reproduced by the complex ocean-atmosphere circulation models currently used to simulate the climatic response to increased greenhouse gases. Its presence is likely to lessen the mean 20th-century global temperature change in model simulations. PMID:9020074

  19. Trends in Surface Temperature at High Latitudes

    NASA Technical Reports Server (NTRS)

    Comiso, Josefino C.

    2012-01-01

    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

  20. Temperature And Precipitation Trends Of Moscow During Xx C Entury

    NASA Astrophysics Data System (ADS)

    Liachov, A. A.; Rubinstein, K. G.; Ginzburg, A. S.

    Moscow is one of the largest megalopolis of Europe. The report is a step to study Moscow agglomeration climate. The analysis is based on the data set of 21 meteorological observing stations in Moscow-district and 5 Moscow-town meteorological observing stations. Trend of temperature (from 1879) and precipitation (from 1936) variations since up to 2000 year are analyzed. It was indicated decrease of summer temperatures and precipitation at all stations and increase of winter temperatures. The decrease of summer temperatures is almost similar at different stations; the increase of winter temperatures goes on with different rates and is more intensive than the decrease of summer temperatures. In this work the tendencies of variation in summer and winter temperature and difference in precipitation regimes on west and east sides of Moscow are considered. The performed analysis of the temperature and precipitation for the 60-year period over a number of Moscow and Moscow-suburbs stations gives opportunity to compare estimates of linear trends for different stage of city development. We study the relations between the urban climate changes and the anthropogenic influence of the city, and how the regional features of global climate effect the urban climate changes.

  1. The Influence of Logger Bias on Reported Temperature Trends: Implications for Temperature Monitoring Networks

    NASA Astrophysics Data System (ADS)

    Malcolm, I.; Fryer, R. J.; Bacon, P. J.; Stirling, D.

    2015-12-01

    There has been increasing interest in river temperature monitoring and research in recent years. This has been driven by factors including a greater awareness of the importance of river temperature for freshwater ecology, the potential for detrimental extremes under climate change and the availability of increasingly affordable dataloggers. A number of studies have attempted to collate and analyse pre-existing long-term (decadal) datasets to assess for evidence of temporal trends. These studies require considerable care given the magnitude of temporal trends (often < 1 degree per decade), the low signal to noise ratio in the data and the potential for bias across different makes, models and individual dataloggers. Despite these issues, data quality control often receives only a superficial consideration with subjective assessments of data quality or a reliance on manufacturer reported accuracy with consequences for the reliability and interpretation of findings. This study assessed the potential influence of logger bias on reported temperature trends in the Girnock Burn, Scotland over > 25 years. The bias of temperature measurements made by different dataloggers (two makes and five models) was determined through cross-calibration against a reference datalogger. Long-term trends in stream temperature metrics (daily mean, max, min) were characterised using Generalised Additive Mixed Models (GAMM). Models were fitted to (1) the raw data and (2) data corrected for logger bias. Significant non-linear temporal trends were observed in the raw data. These trends were accentuated when corrected for logger bias. Given the potential to accentuate or remove long-term trends, it is suggested that robust internal and external calibration and quality control procedures should be established for new temperature networks. Such approaches are capable of removing logger bias and improving accuracy by an order of magnitude over manufacturer stated values.

  2. Estimating population trends with a linear model: technical comments

    USGS Publications Warehouse

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

    2004-01-01

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

  3. Trend Detection in Regional-Mean Temperature Series: Maximum, Minimum, Mean, Diurnal Range, and SST.

    NASA Astrophysics Data System (ADS)

    Zheng, Xiaogu; Basher, Reid E.; Thompson, Craig S.

    1997-02-01

    Regional climate trends are of interest both for understanding natural climate processes and as tests of anthropogenic climate change signatures. Relative to global trends, however, their detection is hampered by smaller datasets and the influence of regional climate processes such as the Southern Oscillation. Regional trends are often presented by authors without demonstration of statistical significance. In this paper, regional-average annual series of air temperature and sea surface temperature for the New Zealand region are analyzed using a systematic statistical approach that selects the optimum statistical model (with respect to serial correlation, linearity, etc.), explicitly models the interannual variability associated with observable regional climate processes, and tests significance. It is found that the residuals are stationary and are a red noise process [ARMA(1,0)] for all the series examined. The SOI and a meridional circulation anomaly index (both high-pass filtered) are `explanatory variables' for interannual variability. For national-average air temperature (AT), linear and exponential trend models are equally valid but for simplicity the linear model is preferred. Failure to model the serial correlation in AT would result in an estimated confidence interval for trend that is too small by 36%. The use of the explanatory variables tightens the confidence interval by 15%.Significant trends were detected. The trend in AT for 1896-1994 is 0.11 ± 0.035°C decade1 (95% confidence interval). This is about double the trend reported for global data, which may be due to the relative absence of sulfate aerosols in the South Pacific region. The trends in maximum and minimum temperature over this period are not statistically different. However, for the later period of 1951-90, the trend in maximum temperature reduces to an insignificant value, while the trend in minimum temperature remains high, resulting in a significant downward trend in diurnal range of 0

  4. Trends in high temperature gas turbine materials

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Bajat, Branislav; Blagojević, Dragan; Kilibarda, Milan; Luković, Jelena; Tošić, Ivana

    2015-07-01

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

  6. Evaluation of rainfall and temperature trends in Brunei Darussalam

    NASA Astrophysics Data System (ADS)

    Hasan, Dk. Siti Nurul Ain binti Pg. Ali; Ratnayake, Uditha; Shams, Shahriar

    2016-02-01

    Climate change is acknowledged as the world's significant environmental predicament. Rainfall and temperature have been widely studied in correlation with climate change. This paper demonstrates the result of the trend analysis of rainfall variables over the period of 1984 to 2013 and temperature variables over the period of 1979 to 2013 in Brunei Darussalam. Mann-Kendall trend test was applied to analyse and detect trends for the variables. This study revealed that the observed rainfall has a statistically significant increasing trend with increasing rainfall duration and decreasing intensity. The annual rainfall has increased significantly at a rate of 26.16 mm per annum. Mann-Kendall test for rainfall data reveals an increasing trend at confidence level of 95% for the annual total rainfall and confidence of level 90% for of annual maximum rainfall. The observed temperature also exhibits a statistically significant increasing trend at a rate of 0.031°C per year. Results of Mann-Kendall test for temperature data indicate a positive trend at a confidence level of 99.9% for the annual average temperature, average day time temperature, minimum day time temperature, average night time temperature and minimum night time temperature and at a confidence level of 95% for maximum night time temperature. The progressive effect of both the observed rainfall and temperature changes will contribute to greater surfaces run off and create flooding problem. Too much rainfall will threaten slope stability while dry periods of increased temperature will cause soil erosion.

  7. How do CGCMs Match the Latest Precipitation and Surface Temperature Trends Over Mexico?

    NASA Astrophysics Data System (ADS)

    Montero-Martinez, M. J.; Pavon-Gonzalez, N.; Arreola-Contreras, J. L.

    2008-05-01

    One of the key regional climate issues is to corroborate whether the expected future climate trends estimated by the CGCMs for a given region are already being detected by recent historic climate trends. In this presentation, we assessed precipitation and mean surface temperature linear trends over Mexico for the 1980-1999 period based on several regional and global databases. Linear approximation is used mainly because we have a climatically small period in which all the databases coincide and because the method is rather simple and provides a very concise view of climate change. However, it is also known that the linear model is a very poor representation of "large" scale temperature trends (Soon et al., 2004). In addition we calculate historic and future trends given by the average of the ensemble of CGCMs which participated for the recent 4th IPCC Assessment Report. We compare the models trends against the "observed" trends and give our results for nine regions around Mexico. Preliminary results for precipitation show that the observed historical trends already look at a drier central and southern part of Mexico, such as the ensamble CGCMs average estimates for the next few decades.

  8. Global patterns in lake surface temperature trends

    NASA Astrophysics Data System (ADS)

    O'Reilly, C.; Sharma, S.; Gray, D.; Hampton, S. E.; Read, J. S.; Rowley, R.; McIntyre, P. B.; Lenters, J. D.; Schneider, P.; Hook, S. J.

    2014-12-01

    Temperature profoundly affects dynamics in the water bodieson which human societies depend worldwide. Even relatively small water temperature changes can alter lake thermal structure with implications for water level, nutrient cycling, ecosystem productivity, and food web dynamics. As air temperature increases with climate change and human land use transforms watersheds, rising water temperatures have been reported for individual lakes or regions, but a global synthesis is lacking; such a synthesis is foundational for understanding the state of freshwater resources. We investigated global patterns in lake surface water temperatures between 1985 and 2009 using in-situ and satellite data from 236 lakes. We demonstrate that lakes are warming significantly around the globe, at an average rate of 0.34 °C per decade. The breadth of lakes in this study allowed examination of the diversity of drivers across global lakes, and highlighted the importance of ice cover in determining the suite of morphological and climate drivers for lake temperature dynamics. These empirical results are consistent with modeled predictions of climate change, taking into account the extent to which water warming can be modulated by local environmental conditions and thus defy simple correlations with air temperature. The water temperature changes we report have fundamental importance for thermal structure and ecosystem functioning in global water resources; recognition of the extent to which lakes are currently in transition should have broad implications for regional and global models as well as for management.

  9. Stratospheric ozone affects mesospheric temperature trends

    NASA Astrophysics Data System (ADS)

    Schultz, Colin

    2012-01-01

    Since 1961, temperatures in the summer mesosphere have undergone a series of reversals. From 1961 to 1979 the atmospheric layer that stretches from roughly 50- to 100-kilometer altitude cooled by 0.5 K per decade. In the subsequent 2 decades the rate of cooling escalated to -3 to -5 K per decade, while the next 10 years saw a mild recovery. Though these temperature flips are seen in the observational record, they have never been reliably re-created in computer models of the middle atmosphere. Unlike the troposphere or stratosphere, for which there are extensive records, observations of mesospheric temperature are limited to point-source detections, making accurate modeling particularly important.

  10. Linear and nonlinear trending and prediction for AVHRR time series data

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Galdies, C.

    2012-08-01

    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.

  12. Interpretation of Recent Temperature Trends in California

    SciTech Connect

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

    2007-09-21

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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 (ΔTw) 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, ΔTw, 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

  14. Are Karakoram temperatures out of phase compared to hemispheric trends?

    NASA Astrophysics Data System (ADS)

    Asad, Fayaz; Zhu, Haifeng; Zhang, Hui; Liang, Eryuan; Muhammad, Sher; Farhan, Suhaib Bin; Hussain, Iqtidar; Wazir, Muhammad Atif; Ahmed, Moinuddin; Esper, Jan

    2016-07-01

    In contrast to a global retreating trend, glaciers in the Karakoram showed stability and/or mass gaining during the past decades. This "Karakoram Anomaly" has been assumed to result from an out-of-phase temperature trend compared to hemispheric scales. However, the short instrumental observations from the Karakoram valley bottoms do not support a quantitative assessment of long-term temperature trends in this high mountain area. Here, we presented a new April-July temperature reconstruction from the Karakoram region in northern Pakistan based on a high elevation (~3600 m a.s.l.) tree-ring chronology covering the past 438 years (AD 1575-2012). The reconstruction passes all statistical calibration and validation tests and represents 49 % of the temperature variance recorded over the 1955-2012 instrumental period. It shows a substantial warming accounting to about 1.12 °C since the mid-twentieth century, and 1.94 °C since the mid-nineteenth century, and agrees well with the Northern Hemisphere temperature reconstructions. These findings provide evidence that the Karakoram temperatures are in-phase, rather than out-of-phase, compared to hemispheric scales since the AD 1575. The synchronous temperature trends imply that the anomalous glacier behavior reported from the Karakoram may need further explanations beyond basic regional thermal anomaly.

  15. Spatiotemporal trends in mean temperatures and aridity index over Rwanda

    NASA Astrophysics Data System (ADS)

    Muhire, I.; Ahmed, F.

    2016-01-01

    This study aims at quantifying the trends in mean temperatures and aridity index over Rwanda for the period of 1961-1992, based on analysis of climatic data (temperatures, precipitations, and potential evapotranspiration). The analysis of magnitude and significance of trends in temperatures and aridity index show the degree of climate change and mark the level of vulnerability to extreme events (e.g., droughts) in different areas of the country. The study reveals that mean temperatures increased in most parts of the country, with a significant increase observed in the eastern lowlands and in the southwestern parts. The highlands located in the northwest and the Congo-Nile crest showed a nonsignificant increase in mean temperatures. Aridity index increased only in March, April, October, and November, corresponding with the rainy seasons. The remaining months of the year showed a decreasing trend. At an annual resolution, the highlands and the western region showed a rise in aridity index with a decreasing pattern over the eastern lowlands and the central plateau. Generally, the highlands presented a nonsignificant increase in mean temperatures and aridity index especially during the rainy seasons. The eastern lowlands showed a significant increase in mean temperatures and decreasing trends in aridity index. Therefore, these areas are bound to experience more droughts, leading to reduced water and consequent decline in agricultural production. On the other hand, the north highlands and southwest region will continue to be more productive.

  16. The Trends of Soil Temperature Change Associated with Air Temperature Change in Korea from 1973 to 2012

    NASA Astrophysics Data System (ADS)

    Lee, Bo-Hyun; Park, Byeong-Hak; Koh, Eun-Hee; Lee, Kang-Kun

    2015-04-01

    Examining long-term trends of the soil temperature can contribute to assessing subsurface thermal environment. The recent 40-year (1973-2012) meteorological data from 14 Korea Meteorological Administration (KMA) stations was analyzed in this study to estimate the temporal variations of air and soil temperatures (at depths 0.5 and 1.0m) in Korea and their relations. The information on regional characteristics of study sites was also collected to investigate the local and regional features influencing the soil temperature. The long-term increasing trends of both air and soil temperatures were estimated by using simple linear regression analysis. The air temperature rise and soil temperature rise were compared for every site to reveal the relation between air and soil temperature changes. In most sites, the proportion of soil temperature rise to air temperature rise was nearly one to one except a few sites. The difference between the air and soil temperature trends at those sites may be attributed to the combined effect of soil properties such as thermal diffusivity and soil moisture content. The impact of urbanization on the air and soil temperature was also investigated in this study. Establishment of the relationship between the air and soil temperatures can help predicting the soil temperature change in a region where no soil temperature data is obtained by using air temperature data. For rigorous establishment of the relationship between soil and air temperatures, more thorough investigation on the soil thermal properties is necessary through additional monitoring and accompanied validation of the proposed relations. Keywords : Soil temperature, Air temperature, Cross-correlation analysis, Soil thermal diffusivity, Urbanization effect Acknowledgement This work was supported by the research project of "Advanced Technology for Groundwater Development and Application in Riversides (Geowater+)" in "Water Resources Management Program (code 11 Technology Innovation C05

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

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

  18. Room Temperature Giant and Linear Magnetoresistance in Topological Insulator Bi2Te3 Nanosheets

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Mohsin, Tanzina; Gough, William A.

    2010-08-01

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

  20. Trends in rainfall and temperature extremes in Morocco

    NASA Astrophysics Data System (ADS)

    Khomsi, K.; Mahe, G.; Tramblay, Y.; Sinan, M.; Snoussi, M.

    2015-02-01

    In Morocco, socioeconomic fields are vulnerable to weather extreme events. This work aims to analyze the frequency and the trends of temperature and rainfall extreme events in two contrasted Moroccan regions (the Tensift in the semi-arid South, and the Bouregreg in the sub-humid North), during the second half of the 20th century. This study considers long time series of daily extreme temperatures and rainfall, recorded in the stations of Marrakech and Safi for the Tensift region, and Kasba-Tadla and Rabat-Sale for the Bouregreg region, data from four other stations (Tanger, Fes, Agadir and Ouarzazate) from outside the regions were added. Extremes are defined by using as thresholds the 1st, 5th, 90th, 95th, and 99th percentiles. Results show upward trends in maximum and minimum temperatures of both regions and no generalized trends in rainfall amounts. Changes in cold events are larger than those for warm events, and the number of very cold events decrease significantly in the whole studied area. The southern region is the most affected with the changes of the temperature regime. Most of the trends found in rainfall heavy events are positive with weak magnitudes even though no statistically significant generalized trends could be identified during both seasons.

  1. Temperature Trends in the TOVS Pathfinder Path A Data Set

    NASA Technical Reports Server (NTRS)

    Susskind, J.; Einaudi, Franco (Technical Monitor)

    2000-01-01

    TOVS (Tiros Operational Vertical Sounder) is the suite of infra-red and microwave sounding instruments, including HIRS-2 and MSU, that have flown on the NOAA Polar orbiting operational satellites TIROS-N, NOAA 6-14 from November 1978 to the present day. Data has been analyzed for the entire time period using a consistent methodology to produce twice daily per satellite global fields of surface skin temperature, atmospheric temperature-moisture profile, cloud top pressure, and fractional cloud cover, OLR and clear sky OLR, and precipitation. All parameters were found to depend on the orbit time of observation which differed as a function of time both because of differing initial satellite orbits and orbit drift. This must be accounted for before one can attempt to find trends in the data. Methodology to account for orbit drift will be shown. Trends will then be shown, over the 21 year period 1979-1999, for surface skin temperature and atmospheric temperature profile. There has been global warming near the surface which falls off rapidly with height. Trends will also be shown for values of MSU2R and MSU4 which are computed from the soundings. These will be compared to trends of MSU2R and MSU4 observed by Spencer and Christy. There is generally good agreement between Spencer and Christy MSU2R trends and those computed from the TOVS Pathfinder data set, with the largest differences over the tropics.

  2. Trends and Patterns of Change in Temperature and Evaporation

    NASA Astrophysics Data System (ADS)

    Ragno, E.; AghaKouchak, A.

    2014-12-01

    Global mean monthly temperature has increased substantially in the past decades. On the other hand, there are contradictory reports on the response of the potential evaporation to a warming climate. In this study, ground based observations of temperature, and direct measurements of pan potential evaporation are evaluated across the United States. Furthermore, empirical simulations of the potential evaporation have been evaluated against observations. The results show that empirical (e.g., Thornthwaite method) estimates of the potential evapotranspiration show trends inconsistent with the ground-based observations. In fact, while temperature data show a significant upward trend across most of the United States, ground-based evaporation data in most locations do not exhibit a statistically significant trend. Empirical methods of potential evaporation estimation, including the Thornthwaite method, show trends similar to temperature. The primary reason is that many of the empirical approaches are dominated by temperature. Currently, empirical estimates of potential evaporation are widely used for numerous applications including water stress analysis. This indicates that using empirical estimates of potential estimation for irrigation water demand estimation and also drought assessment could lead to unrealistic results.

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    Though primarily driven by insolation changes associated with well-known variations in Earth's astronomical parameters, the response of the climate system during interglacials includes a diversity of feedbacks involving the atmosphere, ocean, sea ice, vegetation and land ice. A thorough multi-model-data comparison is essential to assess the ability of climate models to resolve interglacial temperature trends and to help in understanding the recorded climatic signal and the underlying climate dynamics. We present the first multi-model-data comparison of transient millennial-scale temperature changes through two intervals of the Present Interglacial (PIG; 8-1.2 ka) and the Last Interglacial (LIG; 123-116.2 ka) periods. We include temperature trends simulated by 9 different climate models, alkenone-based temperature reconstructions from 117 globally distributed locations (about 45% of them within the LIG) and 12 ice-core-based temperature trends from Greenland and Antarctica (50% of them within the LIG). The definitions of these specific interglacial intervals enable a consistent inter-comparison of the two intervals because both are characterised by minor changes in atmospheric greenhouse gas concentrations and more importantly by insolation trends that show clear similarities. Our analysis shows that in general the reconstructed PIG and LIG Northern Hemisphere mid-to-high latitude cooling compares well with multi-model, mean-temperature trends for the warmest months and that these cooling trends reflect a linear response to the warmest-month insolation decrease over the interglacial intervals. The most notable exception is the strong LIG cooling trend reconstructed from Greenland ice cores that is not simulated by any of the models. A striking model-data mismatch is found for both the PIG and the LIG over large parts of the mid-to-high latitudes of the Southern Hemisphere where the data depicts negative temperature trends that are not in agreement with near zero

  4. Temperature Errors in Linearizing Resistance Networks for Thermistors

    NASA Astrophysics Data System (ADS)

    White, D. R.

    2015-12-01

    It is well known that a single negative-temperature-coefficient thermistor can be linearized over a narrow temperature range by connecting a single resistor in parallel with the thermistor. With the linearizing resistor properly chosen for the operating temperature, the residual errors are proportional to the cube of the temperature range and have a peak value of about 0.2° C for a 30° C range. A greater range of temperatures can be covered or greater linearity be achieved by cascading thermistor-resistor combinations. This paper investigates the limits of the linearity performance of such networks by using interpolation to model their behavior. A simple formula is derived for estimating the residual non-linearity as a function of the number of thermistors, the temperature range covered by the network, and the constant characterizing the exponential temperature dependence of the thermistors. Numerical simulations are used to demonstrate the validity of the formula. Guidelines are also given for circuit topologies for realizing the networks, for optimizing the design of the networks, and for calculating the sensitivities to relative errors in the component values.

  5. Is the global mean temperature trend too low?

    NASA Astrophysics Data System (ADS)

    Venema, Victor; Lindau, Ralf

    2015-04-01

    The global mean temperature trend may be biased due to similar technological and economic developments worldwide. In this study we want to present a number of recent results that suggest that the global mean temperature trend might be steeper as generally thought. In the Global Historical Climate Network version 3 (GHCNv3) the global land surface temperature is estimated to have increased by about 0.8°C between 1880 and 2012. In the raw temperature record, the increase is 0.6°C; the 0.2°C difference is due to homogenization adjustments. Given that homogenization can only reduce biases, this 0.2°C stems from a partial correction of bias errors and it seems likely that the real non-climatic trend bias will be larger. Especially in regions with sparser networks, homogenization will not be able to improve the trend much. Thus if the trend bias in these regions is similar to the bias for more dense networks (industrialized countries), one would expect the real bias to be larger. Stations in sparse networks are representative for a larger region and are given more weight in the computation of the global mean temperature. If all stations are given equal weight, the homogenization adjustments of the GHCNv3 dataset are about 0.4°C per century. In the subdaily HadISH dataset one break with mean size 0.12°C is found every 15 years for the period 1973-2013. That would be a trend bias of 0.78°C per century on a station by station basis. Unfortunately, these estimates strongly focus on Western countries having more stations. It is known from the literature that rich countries have a (statistically insignificant) stronger trend in the global datasets. Regional datasets can be better homogenized than global ones, the main reason being that global datasets do not contain all stations known to the weather services. Furthermore, global datasets use automatic homogenization methods and have less or no metadata. Thus while regional data can be biased themselves, comparing them

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    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.

  7. West African warming: Investigating Temperature Trends and their relation between Precipitation Trends over West African Sahel.

    NASA Astrophysics Data System (ADS)

    LY, M., Jr.

    2014-12-01

    It is now admitted that the West African region faces a lot of constraints due to the comprehensiveness of the high climate variability and potential climate change. This is mainly due to the lack of a large number of datasets and long-term records as summarized in the in the IPCC reports. This paper aims to provide improved knowledge and evidence on current and future climate conditions, for better manage climate variability over seasons and from year to year and strengthen the capacity to adapt to future climate change. In this regards, we analyse the evolution of some extreme temperature and precipitation indices over a large area of West Africa. Prior results show a general warming trend at individual stations throughout the region during the period from 1960 to 2010, namely negative trends in the number of cool nights, and positive trends in the number of warm days and length of warm spells. Trends in rainfall-related indices are not as uniform as the ones in temperatures, rather they display marked multi-decadal variability, as expected. To refine analyses of temperature variations and their relation to precipitation we investigated on cluster analysis aimed at distinguishing different sub-regions, such as continental and coastal, and relevant seasons, such as wet, dry/cold and dry warm. This will contribute to significantly lower uncertainties by developing better and more tailored temperature and precipitation trends to inform the user communities on climate related risks, as well as enhance their resilience to food insecurity and other climate related disasters.

  8. Temperature Trends in the White Mountains of New Hampshire

    NASA Astrophysics Data System (ADS)

    Murray, G.; Kelsey, E. P.; Raudzens Bailey, A.

    2014-12-01

    Located at the summit of Mount Washington (1917 m asl; ~800 hPa), the highest peak in the northeastern United States, the Mount Washington Observatory has meticulously recorded hourly temperature, humidity, cloud-cover, and other atmospheric variables for over 80 years using the same standard procedures to ensure high-quality, homogeneous data. Nearby Hubbard Brook Experimental Forest (253 m asl; ~980 hPa), a Long-Term Ecological Research site, has recorded atmospheric and environmental data since 1956. Together, these two sites provide a unique opportunity to evaluate elevation-dependent climate changes. Using Sen's slope and the Mann Kendall non-parameteric test we examine annual and seasonal trends in minimum, maximum, and mean temperatures. Both Mount Washington and Hubbard Brook exhibit 56-yr warming trends for most seasons, however, the magnitudes and statistical significances are variable, suggesting the processes controlling these trends likely differ with elevation. Since 1957, for instance, spring maximum temperatures at Hubbard Brook have warmed 0.32 °C dec-1 and winter minimums have increased 0.54 °C dec-1, both well within the range reported for six neighboring low elevation stations from 1970-2012 (Wake et al, 2014a,b). In comparison, Mount Washington summit seasonal minimum temperature trends are typically weaker, with changes in winter minimums (the largest of the seasons) reaching only 0.33 °C dec-1. In this presentation, we highlight differences between these two long-term records and discuss possible role of moist processes and boundary layer/free troposphere exposure in causing their divergence. Authors are planning to study the effects of humidity and cloud-cover on summit temperatures and to investigate how changes in the frequency with which the summit is exposed to boundary layer and free tropospheric air masses influences these relationships.

  9. Forcing, feedback and internal variability in global temperature trends.

    PubMed

    Marotzke, Jochem; Forster, Piers M

    2015-01-29

    Most present-generation climate models simulate an increase in global-mean surface temperature (GMST) since 1998, whereas observations suggest a warming hiatus. It is unclear to what extent this mismatch is caused by incorrect model forcing, by incorrect model response to forcing or by random factors. Here we analyse simulations and observations of GMST from 1900 to 2012, and show that the distribution of simulated 15-year trends shows no systematic bias against the observations. Using a multiple regression approach that is physically motivated by surface energy balance, we isolate the impact of radiative forcing, climate feedback and ocean heat uptake on GMST--with the regression residual interpreted as internal variability--and assess all possible 15- and 62-year trends. The differences between simulated and observed trends are dominated by random internal variability over the shorter timescale and by variations in the radiative forcings used to drive models over the longer timescale. For either trend length, spread in simulated climate feedback leaves no traceable imprint on GMST trends or, consequently, on the difference between simulations and observations. The claim that climate models systematically overestimate the response to radiative forcing from increasing greenhouse gas concentrations therefore seems to be unfounded. PMID:25631444

  10. Removing Diurnal Cycle Contamination in Satellite-Derived Tropospheric Temperatures: Understanding Tropical Tropospheric Trend Discrepancies

    NASA Astrophysics Data System (ADS)

    Po-Chedley, S.; Thorsen, T. J.; Fu, Q.

    2014-12-01

    Tropical mid-tropospheric temperature (TMT) time series have been constructed by several independent research teams using satellite microwave sounding unit (MSU) measurements beginning in 1978 and advanced MSU (AMSU) measurements since 1998. Despite careful efforts to homogenize the MSU/AMSU measurements, tropical TMT trends disagree by a factor of three even though each analysis uses the same basic data. Previous studies suggest that the discrepancy in tropical TMT temperature trends is largely caused by differences in both the NOAA-9 warm target factor and diurnal drift corrections used by various teams to homogenize the MSU/AMSU measurements. This work introduces a new observationally-based method for removing biases related to satellite diurnal drift. The method relies on minimizing inter-satellite and inter-node drifts by subtracting out a common diurnal cycle determined via linear regression. It is demonstrated that this method is effective at removing intersatellite biases and biases between the ascending (PM) and descending (AM) node of individual satellites in the TMT time series. After TMT bias correction, the ratio of tropical tropospheric temperature trends relative to surface temperature trends is in accord with the ratio from global climate models. It is shown that bias corrections for diurnal drift based on a climate model produce tropical trends very similar to those from the observationally-based correction, with a trend differences smaller than 0.02 K decade-1. Differences among various TMT datasets are explored further. Tropical trends from this work are comparable to those from the Remote Sensing System (RSS) and NOAA datasets despite small differences. Larger differences between this work and UAH are attributed to differences in the treatment of the NOAA-9 target factor and the UAH diurnal cycle correction.

  11. Accessing Recent Trend of Land Surface Temperature from Satellite Observations

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    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.

  12. The contribution of ozone to future stratospheric temperature trends

    NASA Astrophysics Data System (ADS)

    Maycock, A. C.

    2016-05-01

    The projected recovery of ozone from the effects of ozone depleting substances this century will modulate the stratospheric cooling due to CO2, thereby affecting the detection and attribution of stratospheric temperature trends. Here the impact of future ozone changes on stratospheric temperatures is quantified for three representative concentration pathways (RCPs) using simulations from the Fifth Coupled Model Intercomparison Project (CMIP5). For models with interactive chemistry, ozone trends offset ~50% of the global annual mean upper stratospheric cooling due to CO2 for RCP4.5 and 20% for RCP8.5 between 2006-2015 and 2090-2099. For RCP2.6, ozone trends cause a net warming of the upper and lower stratosphere. The misspecification of ozone trends for RCP2.6/RCP4.5 in models that used the International Global Atmospheric Chemistry (IGAC)/Stratosphere-troposphere Processes and their Role in Climate (SPARC) Ozone Database causes anomalous warming (cooling) of the upper (lower) stratosphere compared to chemistry-climate models. The dependence of ozone chemistry on greenhouse gas concentrations should therefore be better represented in CMIP6.

  13. Trends in Observed Summer Daily Temperature Maximum Across Colorado

    NASA Astrophysics Data System (ADS)

    Rangwala, I.; Arvidson, L.

    2015-12-01

    Increases in the anthropogenic greenhouse forcing are expected to increase the tendency for longer and stronger heat waves in summer. We examine if there is a trend in the observed daytime extreme temperature (Tmax) during summer between 1900-2014 at select high quality stations (n=9) across Colorado. We compile daily observations of Tmax and other variables during summer (JJA), and derive and analyze trends in five different extreme metrics from this data that include the maximum five-day Tmax average, warm spell duration index, and the number of days when Tmax exceeds the 95th, 99th, and 99.9th percentile conditions. We find that the 1930s and 2000s in Colorado had some outstandingly hot years, when we also find exceptionally high count of summer Tmax extremes. Five out of the nine stations show increases in extreme temperature indicators in the more recent decades. The variability in trends in the daily summer Tmax extremes across the nine stations correspond with the mean annual warming trends at those stations. We also find that wetter summers have much smaller instances of Tmax extremes as compared to drier summers.

  14. Trend of monthly temperature and daily extreme temperature during 1951-2012 in New Zealand

    NASA Astrophysics Data System (ADS)

    Caloiero, Tommaso

    2016-03-01

    Among several variables affecting climate change and climate variability, temperature plays a crucial role in the process because its variations in monthly and extreme values can impact on the global hydrologic cycle and energy balance through thermal forcing. In this study, an analysis of temperature data has been performed over 22 series observed in New Zealand. In particular, to detect possible trends in the time series, the Mann-Kendall non-parametric test was first applied at monthly scale and then to several indices of extreme daily temperatures computed since 1951. The results showed a positive trend in both the maximum and the minimum temperatures, in particular, in the autumn-winter period. This increase has been evaluated faster in maximum temperature than in minimum one. The trend analysis of the temperature indices suggests that there has been an increase in the frequency and intensity of hot extremes, while most of the cold extremes showed a downward tendency.

  15. Temperature and heat wave trends in northwest Mexico

    NASA Astrophysics Data System (ADS)

    Martínez-Austria, Polioptro F.; Bandala, Erick R.; Patiño-Gómez, Carlos

    2016-02-01

    Increase in temperature extremes is one of the main expected impacts of climate change, as well as one of the first signs of its occurrence. Nevertheless, results emerging from General Circulation Models, while sufficient for large scales, are not enough for forecasting local trends and, hence, the IPCC has called for local studies based on on-site data. Indeed, it is expected that climate extremes will be detected much earlier than changes in climate averages. Heat waves are among the most important and least studied climate extremes, however its occurrence has been only barely studied and even its very definition remains controversial. This paper discusses the observed changes in temperature trends and heat waves in Northwestern Mexico, one of the most vulnerable regions of the country. The climate records in two locations of the region are analyzed, including one of the cities with extreme climate in Mexico, Mexicali City in the state of Baja California and the Yaqui River basin at Sonora State using three different methodologies. Results showed clear trends on temperature increase and occurrence of heat waves in both of the study zones using the three methodologies proposed. As result, some policy making suggestion are included in order to increase the adaptability of the studied regions to climate change, particularly related with heat wave occurrence.

  16. Interaction between temperature, precipitation and snow cover trends in Norway

    NASA Astrophysics Data System (ADS)

    Rizzi, Jonathan; Brox Nilsen, Irene; Stagge, James Howard; Gisnås, Kjersti; Merete Tallaksen, Lena

    2016-04-01

    Northern latitudes are experiencing faster warming than other regions, partly due to the snow--albedo feedback. A reduction in snow cover, which has a strong positive feedback on the energy balance, leads to a lowering of the albedo and thus, an amplification of the warming signal. Norway, in particular, can be considered a "cold climate laboratory" with large gradients in geography and climate that allows studying the effect of changing temperature and precipitation on snow in highly varying regions. Previous research showed that during last decades there has been an increase in air temperature for the entire country and a concurrent reduction in the land surface area covered by snow. However, these studies also demonstrate the sensitivity of the trend analysis to the period of record, to the start and end of the period, and to the presence of extreme years. In this study, we analyse several variables and their spatial and temporal variability across Norway, including mean, minimum and maximum daily temperature, daily precipitation, snow covered area and total snow water equivalent. Climate data is retrieved from seNorge (http://www.senorge.no), an operationally gridded dataset for Norway with a resolution of 1 km2. Analysis primarily focused on three overlapping 30-year periods (i.e., 1961-1990, 1971-2000, 1981-2010), but also tested trend sensitivity by varying period lengths. For each climate variable the Theil-Sen trend was calculated for each 30-year period along with the difference between 30-year mean values. In addition, indices specific to each variable were calculated (e.g. the number of days with a shift from negative to positive temperature values). The analysis was performed for the whole of Norway as well as for separate climatological regions previously defined based on temperature, precipitation and elevation. Results confirm a significant increase in mean daily temperatures and accelerating warming trends, especially during winter and spring

  17. Temperature Icreasing Trend During Recent Four Decades At Riyadh Region

    NASA Astrophysics Data System (ADS)

    Almleaky, Y.; Sharaf, M.; Basurah, H.; Malawi, A.; Euony, S.

    In this paper the data analysis of one element of the meteorological data of old Riyadh, namely air temperature will be discussed. This station is located on the middle province of the Kingdom of Saudi Arabia and of coordinates (46.72 E and 24.65 N). The analysis of each of the global maximum and, the global minimum temperature is given for each year through out five points: its value, the date of occurrence, the day of the year and the Julian day, finally, the day of the year. Some statistics are provided for the smoothed values of the mean daily variation of the air temperature. We finally addressed some graphical representations, e.g. histograms, daily variations with their fitting equation. A preliminary conclusion indicating that there are general increasing trend in the temperature during the recent thirty four years.

  18. Global non-linear effect of temperature on economic production

    NASA Astrophysics Data System (ADS)

    Burke, Marshall; Hsiang, Solomon M.; Miguel, Edward

    2015-11-01

    Growing evidence demonstrates that climatic conditions can have a profound impact on the functioning of modern human societies, but effects on economic activity appear inconsistent. Fundamental productive elements of modern economies, such as workers and crops, exhibit highly non-linear responses to local temperature even in wealthy countries. In contrast, aggregate macroeconomic productivity of entire wealthy countries is reported not to respond to temperature, while poor countries respond only linearly. Resolving this conflict between micro and macro observations is critical to understanding the role of wealth in coupled human-natural systems and to anticipating the global impact of climate change. Here we unify these seemingly contradictory results by accounting for non-linearity at the macro scale. We show that overall economic productivity is non-linear in temperature for all countries, with productivity peaking at an annual average temperature of 13 °C and declining strongly at higher temperatures. The relationship is globally generalizable, unchanged since 1960, and apparent for agricultural and non-agricultural activity in both rich and poor countries. These results provide the first evidence that economic activity in all regions is coupled to the global climate and establish a new empirical foundation for modelling economic loss in response to climate change, with important implications. If future adaptation mimics past adaptation, unmitigated warming is expected to reshape the global economy by reducing average global incomes roughly 23% by 2100 and widening global income inequality, relative to scenarios without climate change. In contrast to prior estimates, expected global losses are approximately linear in global mean temperature, with median losses many times larger than leading models indicate.

  19. Global non-linear effect of temperature on economic production.

    PubMed

    Burke, Marshall; Hsiang, Solomon M; Miguel, Edward

    2015-11-12

    Growing evidence demonstrates that climatic conditions can have a profound impact on the functioning of modern human societies, but effects on economic activity appear inconsistent. Fundamental productive elements of modern economies, such as workers and crops, exhibit highly non-linear responses to local temperature even in wealthy countries. In contrast, aggregate macroeconomic productivity of entire wealthy countries is reported not to respond to temperature, while poor countries respond only linearly. Resolving this conflict between micro and macro observations is critical to understanding the role of wealth in coupled human-natural systems and to anticipating the global impact of climate change. Here we unify these seemingly contradictory results by accounting for non-linearity at the macro scale. We show that overall economic productivity is non-linear in temperature for all countries, with productivity peaking at an annual average temperature of 13 °C and declining strongly at higher temperatures. The relationship is globally generalizable, unchanged since 1960, and apparent for agricultural and non-agricultural activity in both rich and poor countries. These results provide the first evidence that economic activity in all regions is coupled to the global climate and establish a new empirical foundation for modelling economic loss in response to climate change, with important implications. If future adaptation mimics past adaptation, unmitigated warming is expected to reshape the global economy by reducing average global incomes roughly 23% by 2100 and widening global income inequality, relative to scenarios without climate change. In contrast to prior estimates, expected global losses are approximately linear in global mean temperature, with median losses many times larger than leading models indicate. PMID:26503051

  20. Accessing Recent Trend of Land Surface Temperature from Satellite Observations

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

    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.

  1. Mars Exospheric Temperature Trends as Revealed by MAVEN NGIMS Measurements

    NASA Astrophysics Data System (ADS)

    Bougher, Stephen W.; Olsen, Kirk; Roeten, Kali; Bell, Jared; Mahaffy, Paul; Benna, Mehdi; Elrod, Meredith; Jakosky, Bruce

    2015-11-01

    The Martian dayside upper thermosphere and exosphere temperatures (Texo) have been the subject of considerable debate and study since the first Mariner ultraviolet spectrometer (UVS) measurements (1969-1972), up to recent Mars Express SPICAM UVS measurements (2004-present) (e.g., see reviews by Stewart 1987; Bougher et al. 2000, 2014; Müeller-Wodarg et al. 2008; Stiepen et al. 2014). Prior to MAVEN, the Martian upper atmosphere thermal structure was poorly constrained by a limited number of both in-situ and remote sensing measurements at selected locations, seasons, and periods scattered throughout the solar cycle. Nevertheless, it is recognized that the Mars orbit eccentricity determines that both the solar cycle and seasonal variations in upper atmosphere temperatures must be considered together. The MAVEN NGIMS instrument measures the neutral composition of the major gas species (e.g. He, N, O, CO, N2, O2, NO, Ar and CO2) and their major isotopes, with a vertical resolution of ~5 km for targeted species and a target accuracy of <25% for most of these species (Mahaffy et al. 2014; 2015). Corresponding temperatures can now be derived from the neutral scale heights (especially CO2, Ar, and N2) (e.g. Mahaffy et al. 2015; Bougher et al. 2015). Texo mean temperatures spanning ~200 to 300 km are examined for both Deep Dip and Science orbits over 11-February 2015 (Ls ~ 290) to 14-July 2015 (Ls ~ 12). During these times, dayside sampling below 300 km occurred from the dusk terminator, across the dayside, and approaching the dawn terminator. NGIMS temperatures are investigated to extract spatial (e.g. SZA) and temporal (e.g. orbit-to-orbit, seasonal, solar rotational) variability and trends over this sampling period. Solar and seasonal driven trends in Texo are clearly visible, but orbit-to-orbit variability is significant, and demands further investigation to uncover the major drivers that are responsible.

  2. Resistance thermometer has linear resistance-temperature coefficient at low temperatures

    NASA Technical Reports Server (NTRS)

    Kuzyk, W.

    1966-01-01

    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.

  3. Whole season compared to growth-stage resolved temperature trends: implications for US maize yield

    NASA Astrophysics Data System (ADS)

    Butler, E. E.; Mueller, N. D.; Huybers, P. J.

    2014-12-01

    The effect of temperature on maize yield has generally been considered using a single value for the entire growing season. We compare the effect of temperature trends on yield between two distinct models: a single temperature sensitivity for the whole season and a variable sensitivity across four distinct agronomic development stages. The more resolved variable-sensitivity model indicates roughly a factor of two greater influence of temperature on yield than that implied by the single-sensitivity model. The largest discrepancies occur in silking, which is demonstrated to be the most sensitive stage in the variable-sensitivity model. For instance, whereas median yields are observed to be only 53% of typical values during the hottest 1% of silking-stage temperatures, the single-sensitivity model over predicts median yields of 68% whereas the variable-sensitivity model more correctly predicts median yields of 61%. That the variable sensitivity model is also not capable of capturing the full extent of yield losses suggests that further refinement to represent the non-linear response would be useful. Results from the variable sensitivity model also indicate that management decisions regarding planting times, which have generally shifted toward earlier dates, have led to greater yield benefit than that implied by the single-sensitivity model. Together, the variation of both temperature trends and yield variability within growing stages calls for closer attention to how changes in management interact with changes in climate to ultimately affect yields.

  4. Lung cancer mortality trends in Chile and six-year projections using Bayesian dynamic linear models.

    PubMed

    Torres-Avilés, Francisco; Moraga, Tomás; Núñez, Loreto; Icaza, Gloria

    2015-09-01

    The objectives were to analyze lung cancer mortality trends in Chile from 1990 to 2009, and to project the rates six years forward. Lung cancer mortality data were obtained from the Chilean Ministry of Health. To obtain mortality rates, population projections were used, based on the 2002 National Census. Rates were adjusted using the world standard population as reference. Bayesian dynamic linear models were fitted to estimate trends from 1990 to 2009 and to obtain projections for 2010-2015. During the period under study, there was a 19.9% reduction in the lung cancer mortality rate in men. In women, there was increase of 28.4%. The second-order model showed a better fit for men, and the first-order model a better fit for women. Between 2010 and 2015 the downward trend continued in men, while a trend to stabilization was projected for lung cancer mortality in women in Chile. This analytical approach could be useful implement surveillance systems for chronic non-communicable disease and to evaluate preventive strategies. PMID:26578021

  5. Stratospheric temperature trends: impact of ozone variability and the QBO

    NASA Astrophysics Data System (ADS)

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

    2010-02-01

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

  6. Forecasting Groundwater Temperature with Linear Regression Models Using Historical Data.

    PubMed

    Figura, Simon; Livingstone, David M; Kipfer, Rolf

    2015-01-01

    Although temperature is an important determinant of many biogeochemical processes in groundwater, very few studies have attempted to forecast the response of groundwater temperature to future climate warming. Using a composite linear regression model based on the lagged relationship between historical groundwater and regional air temperature data, empirical forecasts were made of groundwater temperature in several aquifers in Switzerland up to the end of the current century. The model was fed with regional air temperature projections calculated for greenhouse-gas emissions scenarios A2, A1B, and RCP3PD. Model evaluation revealed that the approach taken is adequate only when the data used to calibrate the models are sufficiently long and contain sufficient variability. These conditions were satisfied for three aquifers, all fed by riverbank infiltration. The forecasts suggest that with respect to the reference period 1980 to 2009, groundwater temperature in these aquifers will most likely increase by 1.1 to 3.8 K by the end of the current century, depending on the greenhouse-gas emissions scenario employed. PMID:25412761

  7. Amplification of surface temperature trends and variability in thetropical atmosphere

    SciTech Connect

    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

    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.

  8. Trends and variability in East African rainfall and temperature observations

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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).

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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

  10. 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)

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

    2009-11-01

    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.

  11. 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)

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

    2009-12-01

    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.

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

    NASA Technical Reports Server (NTRS)

    Tiao, G. C.

    1992-01-01

    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.

  13. Design and laboratory testing of a prototype linear temperature sensor

    NASA Astrophysics Data System (ADS)

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

    1982-07-01

    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.

  14. Linear magnetoelectricity at room temperature in perovskite superlattices by design

    NASA Astrophysics Data System (ADS)

    Ghosh, Saurabh; Das, Hena; Fennie, Craig J.

    2015-11-01

    Discovering materials that display a linear magnetoelectric (ME) effect at room temperature is a challenge. Such materials could facilitate devices based on the electric field control of magnetism. Here we present simple, chemically intuitive design rules to identify a class of bulk magnetoelectric materials based on the "bicolor" layering of P b n m ferrite perovskites, e.g., LaFeO3/LnFeO3 superlattices, Ln = lanthanide cation. We use first-principles density functional theory calculations to confirm these ideas. We elucidate the origin of this effect and show it is a general consequence of the layering of any bicolor P b n m perovskite superlattice in which the number of constituent layers are odd (leading to a form of hybrid improper ferroelectricity). Our calculations suggest that the ME effect in these superlattices is larger than that observed in the prototypical magnetoelectric materials Cr2O3 and BiFeO3. Furthermore, in these proposed materials, the strength of the linear ME coupling increases with the magnitude of the induced spontaneous polarization which is controlled by the La/Ln cation radius mismatch. We use a simple mean field model to show that the proposed materials order magnetically above room temperature.

  15. Linearity between temperature peak and bioenergy CO2 emission rates

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  16. Non-linear saturation mechanism of electron temperature gradient modes

    SciTech Connect

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

    2012-10-15

    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.

  17. Sensitivity of Tropospheric and Stratospheric Temperature Trends to Radiosonde Data Quality.

    NASA Astrophysics Data System (ADS)

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

    2000-05-01

    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 quality issues.Many radiosonde stations do not have even moderately complete records of monthly mean data for the period 1959-95. In a network of 180 stations (the combined Global Climate Observing System Baseline Upper-Air Network and the network developed by J. K. Angell), only 74 stations meet the data availability requirement of at least 85% of nonmissing months of data for tropospheric levels (850-100 hPa). Extending into the lower stratosphere (up to 30 hPa), only 22 stations have data records meeting this requirement for the same period, and the 30-hPa monthly data are generally based on fewer daily observations than at 50 hPa and below. These networks show evidence of statistically significant tropospheric warming, particularly in the Tropics, and stratospheric cooling for the period 1959-95. However, the selection of different station networks can cause network-mean trend values to differ by up to 0.1 K decade1.The choice of radiosonde dataset used to estimate trends influences the results. Trends at individual stations and pressure levels differ in two independently produced monthly mean temperature datasets. The differences are generally less than 0.1 K decade1, but in a few cases they are larger and statistically significant at the 99% confidence level. These cases are due to periods of record when one dataset has a distinct bias with respect to the other.The statistical method used to estimate linear trends has a small influence on the result. The nonparametric median of pairwise slopes method and the parametric least squares linear regression method

  18. Temperature Trends over Germany from Homogenized Radiosonde Data.

    NASA Astrophysics Data System (ADS)

    Steinbrecht, W.; Pattantyús Ábráham, M.

    2015-12-01

    We present homogenization procedure and results for Germany's historical radiosonde records, dating back to the 1950s. Our manual homogenization makes use of the different RS networks existing in East and West-Germany from the 1950s until 1990. The largest temperature adjustments, up to 2.5K, are applied to Freiberg sondes used in the East in the 1950s and 1960s. Adjustments for Graw H50 and M60 sondes, used in the West from the 1950s to the late 1980s, and for RKZ sondes, used in the East in the 1970s and 1980s, are also significant, 0.3 to 0.5K. Small differences between Vaisala RS80 and RS92 sondes used throughout Germany since 1990 and 2005, respectively, were not corrected for at levels from the ground to 300 hPa. Comparison of the homogenized data with other radiosonde datasets, RICH (Haimberger et al., 2012) and HadAT2 (McCarthy et al., 2008), and with Microwave Sounding Unit satellite data (Mears and Wentz, 2009), shows generally good agreement. HadAT2 data exhibit a few suspicious spikes in the 1970s and 1980s, and some suspicious offsets up to 1K after 1995. Compared to RICH, our homogenized data show slightly different temperatures in the 1960s and 1970s. We find that the troposphere over Germany has been warming by 0.25 ± 0.1K per decade since the early 1960s, slightly more than reported in other studies (Hartmann et al., 2013). The stratosphere has been cooling, with the trend increasing from almost no change near 230hPa (the tropopause) to -0.5 ± 0.2K per decade near 50hPa. Trends from the homogenized data are more positive by about 0.1K per decade compared to the original data, both in troposphere and stratosphere. References: Haimberger, L., C. Tavolato, and S. Sperka, 2012. J. Climate, 25, 8108-8131, doi:10.1175/ JCLI-D-11-00668.1. Hartmann, D., et al., 2013: Observations: Atmosphere and surface in IPCC AR5, Climate Change 2013: The Physical Science Basis. [Available at http://www.ipcc.ch/report/ar5/wg1/.] McCarthy, M., et al., 2008. J. Climate

  19. CMB all-scale blackbody distortions induced by linearizing temperature

    NASA Astrophysics Data System (ADS)

    Notari, Alessio; Quartin, Miguel

    2016-08-01

    Cosmic microwave background (CMB) experiments, such as WMAP and Planck, measure intensity anisotropies and build maps using a linearized formula for relating them to the temperature blackbody fluctuations. However, this procedure also generates a signal in the maps in the form of y -type distortions which is degenerate with the thermal Sunyaev Zel'dovich (tSZ) effect. These are small effects that arise at second order in the temperature fluctuations not from primordial physics but from such a limitation of the map-making procedure. They constitute a contaminant for measurements of our peculiar velocity, the tSZ and primordial y -distortions. They can nevertheless be well modeled and accounted for. We show that the distortions arise from a leakage of the CMB dipole into the y -channel which couples to all multipoles, mostly affecting the range ℓ≲400 . This should be visible in Planck's y -maps with an estimated signal-to-noise ratio of about 12. We note however that such frequency-dependent terms carry no new information on the nature of the CMB dipole. This implies that the real significance of Planck's Doppler coupling measurements is actually lower than reported by the collaboration. Finally, we quantify the level of contamination in tSZ and primordial y -type distortions and show that it is above the sensitivity of proposed next-generation CMB experiments.

  20. Observational evidence of temperature trends at two levels in the surface layer

    NASA Astrophysics Data System (ADS)

    Lin, X.; Pielke, R. A., Sr.; Mahmood, R.; Fiebrich, C. A.; Aiken, R.

    2015-09-01

    Long-term surface air temperatures at 1.5 m screen level over land are used in calculating a global average surface temperature trend. This global trend is used by the IPCC and others to monitor, assess, and describe global warming or warming hiatus. Current knowledge of near-surface temperature trends with respect to height, however, is limited and inadequately understood because surface temperature observations at different heights in the surface layer in the world are rare especially from a high-quality and long-term climate monitoring network. Here we use high-quality two-height Oklahoma Mesonet observations, synchronized in time, fixed in height, and situated in relatively flat terrain, to assess temperature trends and differentiating temperature trends with respect to heights (i.e., near-surface lapse rate trend) over the period 1997 to 2013. We show that the near-surface lapse rate has significantly decreased with a trend of -0.18 ± 0.03 °C (10 m)-1 decade-1 indicating that the 9 m height temperatures increased faster than temperatures at the 1.5 m screen level and conditions at the 1.5 m height cooled faster than at the 9 m height. However, neither of the two individual height temperature trends by themselves were statistically significant. The magnitude of lapse rate trend is greatest under lighter winds at night. Nighttime lapse rate trends were significantly more negative than daytime lapse rate trends and the average lapse rate trend was three times more negative under calm conditions than under windy conditions. Our results provide the first observational evidence of near-surface temperature changes with respect to height that could enhance the assessment of climate model predictions.

  1. Output trends, characteristics, and measurements of three megavoltage radiotherapy linear accelerators.

    PubMed

    Hossain, Murshed

    2014-01-01

    The purpose of this study is to characterize and understand the long-term behavior of the output from megavoltage radiotherapy linear accelerators. Output trends of nine beams from three linear accelerators over a period of more than three years are reported and analyzed. Output, taken during daily warm-up, forms the basis of this study. The output is measured using devices having ion chambers. These are not calibrated by accredited dosimetry laboratory, but are baseline-compared against monthly output which is measured using calibrated ion chambers. We consider the output from the daily check devices as it is, and sometimes normalized it by the actual output measured during the monthly calibration of the linacs. The data show noisy quasi-periodic behavior. The output variation, if normalized by monthly measured "real' output, is bounded between ± 3%. Beams of different energies from the same linac are correlated with a correlation coefficient as high as 0.97, for one particular linac, and as low as 0.44 for another. These maximum and minimum correlations drop to 0.78 and 0.25 when daily output is normalized by the monthly measurements. These results suggest that the origin of these correlations is both the linacs and the daily output check devices. Beams from different linacs, independent of their energies, have lower correlation coefficient, with a maximum of about 0.50 and a minimum of almost zero. The maximum correlation drops to almost zero if the output is normalized by the monthly measured output. Some scatter plots of pairs of beam output from the same linac show band-like structures. These structures are blurred when the output is normalized by the monthly calibrated output. Fourier decomposition of the quasi-periodic output is consistent with a 1/f power law. The output variation appears to come from a distorted normal distribution with a mean of slightly greater than unity. The quasi-periodic behavior is manifested in the seasonally averaged output

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

    PubMed Central

    Hossain, Murshed

    2015-01-01

    The purpose of this study is to characterize and understand the long term behavior of the output from megavoltage radiotherapy linear accelerators. Output trends of nine beams from three linear accelerators over a period of more than three years are reported and analyzed. Output taken during daily warm-up forms the basis of this study. The output is measured using devices having ion-chambers. These are not calibrated by accredited dosimetry laboratory but are baseline compared against monthly output which are measured using calibrated ion-chambers. We consider the output from the daily check devices as it is and sometimes normalized them by the actual output measured during the monthly calibration of the Linacs. The data shows noisy quasi-periodic behavior. The output variation if normalized by monthly measured “real’ output, is bounded between ±3%. Beams of different energies from the same Linac are correlated with a correlation coefficient as high as 0.97 for one particular Linac and as low as 0.44 for another. These maximum and minimum correlations drop to 0.78 and 0.25 when daily output is normalized by the monthly measurements. These results suggest that the origin of these correlations are both the Linacs and the daily output check devices. Beams from different Linacs, independent of their energies, have lower correlation coefficient with a maximum of about 0.50 and a minimum of almost zero. The maximum correlation drops to almost zero if the output is normalized by the monthly measured output. Some scatter plots of pairs of beam-output from the same Linac show band-like structures. These structures are blurred when the output is normalized by the monthly calibrated output. Fourier decomposition of the quasi periodic output is consistent with a 1/f power law. The output variation appears to come from a distorted normal distribution with a mean of slightly greater than unity. The quasi-periodic behavior is manifested in the seasonally averaged output

  3. Subsurface temperature trend in response to exploitation of thermal water in Jiashi Hot Spring, northeastern Taiwan

    NASA Astrophysics Data System (ADS)

    Chen, Wenfu; Chiang, Hsiehtang

    2015-04-01

    Temperature monitoring provides important information for sustainable management of a geothermal field. Previous studies show that decline of aquifer pressure is an obviously indicator of overexploitation for a thermal aquifer. However, many thermal water producing aquifers don't show pressure declining but with subtle temperature change. How to detect the temperature trend is an important topic for sustainable management of a geothermal field. In this study, we use borehole temperatures measured over a half year interval from 2011 to 2014 and Mann-Kendall method to determine the trends of subsurface temperature in Jiashi Hot Spring, northeastern Taiwan. Our results show that trends of subsurface temperature are related to the hydrogeology and flow field of groundwater. Flow directions of groundwater/thermal water are impacted by exploitation of thermal water of production wells, according to the depths and distribution. Repeatedly measured borehole temperature profiles provide important information to depict the trends of subsurface temperature change.

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

    NASA Astrophysics Data System (ADS)

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

    2008-03-01

    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.

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

    USGS Publications Warehouse

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

    2010-01-01

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

  6. Surface Temperature Trends in the Arctic Atlantic Region Over the Last 2,000 Years

    NASA Astrophysics Data System (ADS)

    Korhola, A.; Hanhijarvi, S.; Tingley, M.

    2013-12-01

    We introduce a new reconstruction method that uses the ordering of all pairs of proxy observations within each record to arrive at a consensus time series that best agrees with all proxy records. By considering only pairwise comparisons, this method, which we call PaiCo, facilitates the inclusion of records with differing temporal resolutions, and relaxes the assumption of linearity to the more general assumption of a monotonically increasing relationship between each proxy series and the target climate variable. We apply PaiCo to a newly assembled collection of high-quality proxy data to reconstruct the mean temperature of the Northernmost Atlantic region, which we call Arctic Atlantic, over the last 2,000 years. The Arctic Atlantic is a dynamically important region known to feature substantial temperature variability over recent millennia, and PaiCo allows for a more thorough investigation of the Arctic Atlantic regional climate as we include a diverse array of terrestrial and marine proxies with annual to multidecadal temporal resolutions. Comparisons of the PaiCo reconstruction to recent reconstructions covering larger areas indicate greater climatic variability in the Arctic Atlantic than for the Arctic as a whole. The Arctic Atlantic reconstruction features temperatures during the Roman Warm Period and Medieval Climate Anomaly that are comparable or even warmer than those of the twentieth century, and coldest temperatures in the middle of the nineteenth century, just prior to the onset of the recent warming trend.

  7. Incorporating duplicate genotype data into linear trend tests of genetic association: methods and cost-effectiveness.

    PubMed

    Borchers, Bryce; Brown, Marshall; McLellan, Brian; Bekmetjev, Airat; Tintle, Nathan L

    2009-01-01

    The genome-wide association (GWA) study is an increasingly popular way to attempt to identify the causal variants in human disease. Duplicate genotyping (or re-genotyping) a portion of the samples in a GWA study is common, though it is typical for these data to be ignored in subsequent tests of genetic association. We demonstrate a method for including duplicate genotype data in linear trend tests of genetic association which yields increased power. We also consider the cost-effectiveness of collecting duplicate genotype data and find that when the relative cost of genotyping to phenotyping and sample acquisition costs is less than or equal to the genotyping error rate it is more powerful to duplicate genotype the entire sample instead of spending the same money to increase the sample size. Duplicate genotyping is particularly cost-effective when SNP minor allele frequencies are low. Practical advice for the implementation of duplicate genotyping is provided. Free software is provided to compute asymptotic and permutation based tests of association using duplicate genotype data as well as to aid in the duplicate genotyping design decision. PMID:19492982

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

    USGS Publications Warehouse

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

    2006-01-01

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

  9. Trends in extreme daily temperatures and humidex index in the United Arab Emirates over 1948-2014.

    NASA Astrophysics Data System (ADS)

    Yang, H. W.; Ouarda, T.

    2015-12-01

    This study deals with the analysis of the characteristics of extreme temperature events in the Middle East, using NCEP reanalysis gridded data, for the summer (May-October) and winter (November-April) seasons. Trends in the occurrences of three types of heat spells during 1948-2014 are studied by both Linear Regression (LR) and Mann-Kendall (MK) test. Changes in the diurnal temperature range (DTR) are also investigated. To better understand the effects of heat spells on public health, the Humidex, a combination index of ambient temperature and relative humidity, is also used. Using percentile threshold, temperature (Humidex) Type-A and Type-B heat spells are defined respectively by daily maximum and minimum temperature (Humidex). Type-C heat spells are defined as the joint occurrence of Type-A and Type-B heat spells at the same time. In the Middle East, it is found that no coherent trend in temperature Type-A heat spells is observed. However, the occurrences of temperature Type-B and C heat spells have consistently increased since 1948. For Humidex heat spells, coherently increased activities of all three types of heat spells are observed in the area. During the summer, the magnitude of the positive trends in Humidex heat spells are generally stronger than temperature heat spells. More than half of the locations in the area show significantly negative DTR trends in the summer, but the trends vary according to the region in the winter. Annual mean temperature has increased an average by 0.5°C, but it is mainly associated with the daily minimum temperature which has warmed up by 0.84°C.Daily maximum temperature showed no significant trends. The warming is hence stronger in minimum temperatures than in maximum temperatures resulting in a decrease in DTR by 0.16 °C per decade. This study indicates hence that the UAE has not become hotter, but it has become less cold during 1948 to 2014.

  10. Radiative analysis of global mean temperature trends in the middle atmosphere: Effects of non-locality and secondary absorption bands

    NASA Astrophysics Data System (ADS)

    Fomichev, V. I.; Jonsson, A. I.; Ward, W. E.

    2016-02-01

    In this paper, we provide a refined and extended assignment of past and future temperature changes relative to previous analyses and describe and evaluate the relevance of vertical coupling and non-linear and secondary radiative mechanisms for the interpretation of climatic temperature variations in the middle atmosphere. Because of their nature, the latter mechanisms are not adequately accounted for in most regression analyses of temperature trends as a function of local constituent variations. These mechanisms are examined using (1) globally averaged profiles from transient simulations with the Canadian Middle Atmosphere Model (CMAM) forced by changes in greenhouse gases and ozone depleting substances and (2) a one-dimensional radiative-equilibrium model forced using the diagnosed global mean changes in radiatively active constituents as derived from the CMAM model runs. The conditions during the periods 1975 to 1995 and 2010 to 2040 (during which the rates of change in ozone and CO2 differ) provide a suitable contrast for the role of the non-linear and non-local mechanisms being evaluated in this paper to be clearly differentiated and evaluated. Vertical coupling of radiative transfer effects and the influence of secondary absorption bands are important enough to render the results of multiple linear regression analyses between the temperature response and constituent changes misleading. These effects are evaluated in detail using the 1D radiative-equilibrium model using profiles from the CMAM runs as inputs. In order to explain the differences in the CMAM temperature trends prior to and after 2000 these other radiative effects must be considered in addition to local changes in the radiatively active species. The middle atmosphere temperature cools in response to CO2 and water vapor increases, but past and future trends are modulated by ozone changes.

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

    NASA Astrophysics Data System (ADS)

    Christiansen, Bo

    2010-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

    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

  13. Discussion on linear long-term trends in aerosol and cloud properties over India and its surrounding waters

    NASA Astrophysics Data System (ADS)

    Sreekanth, V.

    2016-05-01

    Spatial and seasonal variations in the linear long-term trend estimates of aerosol and cloud properties over Indian subcontinent and the surrounding oceanic regions of Bay of Bengal (BoB) and Arabian Sea (AS) are studied and discussed utilizing 12 complete years (2003-2014) of Moderate Resolution Imaging Spectroradiometer (MODIS) derived Aerosol and cloud products. Annual Aerosol Optical Depth (AOD) trends (in terms of AOD/year) are found to be positive (upward) over most of the study region with a spatial mean (median) value of ∼0.0065 (0.0064) and exhibited significant spatial and seasonal heterogeneity. Over Indian landmass AOD trends and their statistical significance decreased towards north along the Indo-Gangetic plains (IGP), for which the probable causes are discussed. Same kind of pattern in AOD trends has been observed as we move deeper into the oceanic regions of BoB and AS, away from Indian subcontinent. Observed trend patterns are discussed in light of the possible increase in emissions (over Indian landmass) and transported aerosol component, co-variation with trends in meteorological parameters and their possible feedbacks. Trend maps in seasonal AOD are shown to understand the aerosol build up over the study region under varying meteorological conditions. Seasonal AOD trend patterns resembled the synoptic scale wind circulation over the study region revealing that the upward trend in aerosol abundance over the adjoining oceanic regions of India is a result of effective transport of increasing emissions over India on to them. No significant trends in cloud properties (over the whole study region) are depicted in concert with that of aerosols, except over few pockets. The study also highlighted the role of large scale atmospheric processes in modulating the shape of the AOD time series over the regions with significant abundance of natural aerosol component (dust).

  14. Trends in indices of daily temperature and precipitations extremes in Morocco

    NASA Astrophysics Data System (ADS)

    Filahi, S.; Tanarhte, M.; Mouhir, L.; El Morhit, M.; Tramblay, Y.

    2016-05-01

    The purpose of this paper is to provide a summary of Morocco's climate extreme trends during the last four decades. Indices were computed based on a daily temperature and precipitation using a consistent approach recommended by the ETCCDI. Trends in these indices were calculated at 20 stations from 1970 to 2012. Twelve indices were considered to detect trends in temperature. A large number of stations have significant trends and confirm an increase in temperature, showing increased warming during spring and summer seasons. The results also show a decrease in the number of cold days and nights and an increase in the number of warm days and nights. Increasing trends have also been found in the absolute warmest and coldest temperatures of the year. A clear increase is detected for warm nights and diurnal temperature range. Eight indices for precipitation were also analyzed, but the trends for these precipitation indices are much less significant than for temperature indices and show more mixed spatial patterns of change. Heavy precipitation events do not exhibit significant trends except at a few locations, in the north and central parts of Morocco, with a general tendency towards drier conditions. The correlation between these climate indices and the large-scale atmospheric circulations indices such as the NAO, MO, and WEMO were also analyzed. Results show a stronger relationship with these climatic indices for the precipitation indices compared to the temperature indices. The correlations are more significant in the Atlantic regions, but they remain moderate at the whole country scale.

  15. Long-term trends in extreme temperatures in Hong Kong and southern China

    NASA Astrophysics Data System (ADS)

    Lee, T. C.; Chan, H. S.; Ginn, E. W. L.; Wong, M. C.

    2011-01-01

    The observed long-term trends in extreme temperatures in Hong Kong were studied based on the meteorological data recorded at the Hong Kong Observatory Headquarters from 1885-2008. Results show that, over the past 124 years, the extreme daily minimum and maximum temperatures, as well as the length of the warm spell in Hong Kong, exhibit statistically significant long-term rising trends, while the length of the cold spell shows a statistically significant decreasing trend. The time-dependent return period analysis also indicated that the return period for daily minimum temperature at 4°C or lower lengthened considerably from 6 years in 1900 to over 150 years in 2000, while the return periods for daily maximum temperature reaching 35°C or above shortened drastically from 32 years in 1900 to 4.5 years in 2000. Past trends in extreme temperatures from selected weather stations in southern China from 1951-2004 were also assessed. Over 70% of the stations studied yielded a statistically significant rising trend in extreme daily minimum temperature, while the trend for extreme maximum temperatures was found to vary, with no significant trend established for the majority of stations.

  16. Extreme temperature trends in major cropping systems and their relation to agricultural land use change

    NASA Astrophysics Data System (ADS)

    Mueller, N. D.; Butler, E. E.; McKinnon, K. A.; Rhines, A. N.; Tingley, M.; Siebert, S.; Holbrook, N. M.; Huybers, P. J.

    2015-12-01

    High temperature extremes during the growing season can reduce agricultural production. At the same time, agricultural practices can modify temperatures by altering the surface energy budget. Here we investigate growing season climate trends in major cropping systems and their relationship with agricultural land use change. In the US Midwest, 100-year trends exhibit a transition towards more favorable conditions, with cooler summer temperature extremes and increased precipitation. Statistically significant correspondence is found between the cooling pattern and trends in cropland intensification, as well as with trends towards greater irrigated land over a small subset of the domain. Land conversion to cropland, often considered an important influence on historical temperatures, is not significantly associated with cooling. We suggest that cooling is primarily associated with agricultural intensification increasing the potential for evapotranspiration, consistent with our finding that cooling trends are greatest for the highest temperature percentiles, and that increased evapotranspiration generally leads to greater precipitation. Temperatures over rainfed croplands show no cooling trend during drought conditions, consistent with evapotranspiration requiring adequate soil moisture, and implying that modern drought events feature greater warming as baseline cooler temperatures revert to historically high extremes. Preliminary results indicate these relationships between temperature extremes, irrigation, and intensification are also observed in other major summer cropping systems, including northeast China, Argentina, and the Canadian Prairies.

  17. The identification of distinct patterns in California temperature trends

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  18. Trends and projections of temperature, precipitation, and snow cover during snow cover-observed period over southwestern Iran

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    In the present study, tendencies in temperature, precipitation, and snow cover area over the southwestern part of Iran have been assessed. The research mainly focused on snow cover-observed period which included the months of December, January, February, March, and April in the area. This research has been divided into two parts. First part consists of an analysis of the trends in temperature, precipitation, and snow cover area during the above months. Trends in these parameters were tested by linear regression, and significance was determined by t test. Mann-Kendall rank test (MK test) was also employed to confirm the results of linear regression. Sequential Mann-Kendall test (SQ-MK test) was applied for change point detection in the series. For snow cover analysis, remote sensing images from National Oceanic and Atmospheric Administration (NOAA) satellite with advanced very high resolution radiometer (AVHRR) sensor for the period 1987-2007 were used. The second part of the research involved future projections based on four models under B1 and A1B emission scenarios. The models used were centre national de recherches meteorologiques (CNRM), European Center Hamburg model (ECHAM), Model for Interdisciplinary Research on Climate (MIROCH) and United Kingdom Meteorological Office (UKMOC) under the Intergovernmental Panel on Climate Change (IPCC) AR4. The analysis of temperature trends revealed a significant increase during February and April. Temperature projections showed that temperature may increase between 1.12 to 7.87 °C by 2100 in the study area. The results of precipitation series indicated that majority of the stations registered insignificant trends during the twentieth century. However, precipitation may decrease according to most of the models under both scenarios, but the decrease may not be large, except according to MIROCH model. The results of trend analysis of snow cover area indicated that no significant trends were detected by any statistical tests

  19. 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)

    Remsberg, Ellis E.

    2009-01-01

    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.

  20. Modelling uncertainties and possible future trends of precipitation and temperature for 10 sub-basins in Columbia River Basin (CRB)

    NASA Astrophysics Data System (ADS)

    Ahmadalipour, A.; Rana, A.; Qin, Y.; Moradkhani, H.

    2014-12-01

    Trends and changes in future climatic parameters, such as, precipitation and temperature have been a central part of climate change studies. In the present work, we have analyzed the seasonal and yearly trends and uncertainties of prediction in all the 10 sub-basins of Columbia River Basin (CRB) for future time period of 2010-2099. The work is carried out using 2 different sets of statistically downscaled Global Climate Model (GCMs) projection datasets i.e. Bias correction and statistical downscaling (BCSD) generated at Portland State University and The Multivariate Adaptive Constructed Analogs (MACA) generated at University of Idaho. The analysis is done for with 10 GCM downscaled products each from CMIP5 daily dataset totaling to 40 different downscaled products for robust analysis. Summer, winter and yearly trend analysis is performed for all the 10 sub-basins using linear regression (significance tested by student t test) and Mann Kendall test (0.05 percent significance level), for precipitation (P), temperature maximum (Tmax) and temperature minimum (Tmin). Thereafter, all the parameters are modelled for uncertainty, across all models, in all the 10 sub-basins and across the CRB for future scenario periods. Results have indicated in varied degree of trends for all the sub-basins, mostly pointing towards a significant increase in all three climatic parameters, for all the seasons and yearly considerations. Uncertainty analysis have reveled very high change in all the parameters across models and sub-basins under consideration. Basin wide uncertainty analysis is performed to corroborate results from smaller, sub-basin scale. Similar trends and uncertainties are reported on the larger scale as well. Interestingly, both trends and uncertainties are higher during winter period than during summer, contributing to large part of the yearly change.

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

    USGS Publications Warehouse

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

    2014-01-01

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

  2. Temperature increasing trend due to solar activity at Western Saudi

    NASA Astrophysics Data System (ADS)

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

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

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

    PubMed Central

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

    2014-01-01

    Background: There are some evidences that control the blood sugar decreasing the risk of diabetes complications, and even fatal. There are so many studies, but they are mostly cross-sectional and ignore the trend and hence it is necessary to implement a longitudinal study. The aim of this prospective study is to find the trend of glycosylated hemoglobin (HbA1c) over time and the associative factors on it. Methods: Participants of this longitudinal study were 3440 eligible diabetes patients referred to Isfahan Endocrine and Metabolism Research Center during 2000-2012 who are measured 2-40 times. A linear mixed model was applied to determine the association between HbA1c and variables, including lipids, systolic, diastolic blood pressure and complications such as nephropathy, and retinopathy. Furthermore, the effect of mentioned variables on trend of HbA1c was determined. Results: The fitted model showed total cholesterol, retinopathy, and the method of therapy including oral antidiabetic drugs (OADs) plus insulin and insulin therapy decreased the trend of HbA1c and high-density lipoprotein, weight, hyperlipidemia and the method of therapy including diet, and OADs increased the trend of HbA1c. Conclusions: The present study shows that regular visits of diabetic patients as well as controlling blood pressure, lipid profile, and weight loss can improve the trend of HbA1c levels during the time. PMID:25400886

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

    NASA Astrophysics Data System (ADS)

    Black, Adam Leland

    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.

  5. Wind speed and temperature trends impacts on reference evapotranspiration in Southern Italy

    NASA Astrophysics Data System (ADS)

    Liuzzo, Lorena; Viola, Francesco; Noto, Leonardo V.

    2016-01-01

    In this study, the impacts of both temperature and wind speed trends on reference evapotranspiration have been assessed using as a case study the Southern Italy, which present a wide variety of combination of such climatic variables trends in terms of direction and magnitude. The existence of statistically significant trends in wind speed and temperature from observational datasets, measured in ten stations over Southern Italy during the period 1968-2004, has been investigated. Time series have been examined using the Mann-Kendall nonparametric statistical test in order to detect possible evidences of wind speed and temperature trends at different temporal resolution and significance level. Once trends have been examined and quantified, the effects of these trends on seasonal reference evapotranspiration have been evaluated using the FAO-56 Penman-Monteith equation. Results quantified the effects of extrapolated temperature and wind speed trends on reference evapotranspiration. Where these climatic drivers are on the same direction, reference evapotranspiration generally increases during the growing season due to a nonlinear overlapping of effects. Whereas wind speed decreases and temperature increases, there is a sort of counterbalancing effect between the two considered climatic forcing in determining future reference evapotranspiration.

  6. Trends of temperature and precipitation extremes in the Loess Plateau Region of China, 1961-2010

    NASA Astrophysics Data System (ADS)

    Wang, Qi-xiang; Wang, Meng-ben; Fan, Xiao-hui; Zhang, Feng; Zhu, Shi-zhong; Zhao, Tian-liang

    2016-05-01

    The spatial and temporal trends of 11 (7) temperature (precipitation) extreme indices are examined for the Loess Plateau Region (LPR) and its southeast and northwest sub-regions based on daily observations at 214 meteorological stations. Results show widespread significant warming trends for all the temperature extremes except for the diurnal temperature range (DTR) and the lowest daily maximum temperature in each year (TXn) during 1961-2010. When regionally averaged, a significant warming trend is detected for all the indices except for DTR and TXn in the past 50 years. Compared with the entire LPR, a significant warming trend is detected for all the indices except for DTR and TXn over the southeast sub-region of LPR; while it is observed for all the indices over the northwest. The trends for these indices are generally stronger in the northwest than in the southeast in the past 50 years. In contrast, for precipitation indices, only a small percentage of areas show significant drying or wetting trends and, when regionally averaged, none of them displays significant trends during the past 50 years. On the sub-regional scale, however, a larger percentage of areas show significant drying trends for precipitation indices generally over the southeast relative to the entire LPR, and noticeably, the sub-regional average heavy precipitation (R10mm) and wet day precipitation (PRCPTOT) display significant decreasing trends during the past 50 years; whereas only a slightly larger percentage of areas show significant wetting trends for these indices over the northwest compared with the entire LPR, and when sub-regionally averaged, none of the indices have significant trends during the past 50 years.

  7. Relating temperature, snow height and glacier characteristics to streamflow trends in Western Austria

    NASA Astrophysics Data System (ADS)

    Kormann, Christoph; Morin, Efrat; Renner, Maik; Francke, Till; Bronstert, Axel

    2014-05-01

    The results of streamflow trend studies are often characterised by mostly insignificant trends. This applies especially for trends of annually averaged runoff: In our study region, Western Austria, we found that there is a trend gradient from high-altitude to low-altitude stations, i.e. a pattern of mostly positive annual trends at higher stations and negative ones at lower stations. At mid-altitudes, trends are mostly insignificant. The trends were most probably caused by the following two main processes: On the one hand, melting glaciers produce excess runoff at high-altitude watersheds. On the other hand, increasing evapotranspiration results in decreasing trends at low-altitude watersheds. However, these patterns are masked at mid-altitudes because the resulting positive and negative trends balance each other. To verify these theories, we attributed the detected trends to specific causes. For this purpose, we analysed trends on a daily basis, as the causes for these changes might be restricted to a smaller temporal scale than the annual one. The daily trends were assessed by calculating 30-day moving average subsets and then estimating significance and magnitude. This allowed for the explicit pointing out of the exact days of year (DOY) when certain streamflow trends emerge and then relating them to the according DOYs of trends and annual cycles of other observed variables, e.g. the DOYs when snow height trends occur or the DOY when temperature crosses the freezing point in spring. Concerning trends caused by increased glacial melt, we applied correlation analyses between glacier area and trend magnitudes during the corresponding DOYs. As a result, the positive trends in spring were attributed to an earlier and more intense snow melt. The ones that follow in late spring at upper stations could be related to increased glacial melt. The negative trends in summertime that turn up earlier at low-altitude stations and later at high-altitude stations are most

  8. Overall false positive rates in tests for linear trend in tumor incidence in animal carcinogenicity studies of new drugs.

    PubMed

    Lin, K K; Rahman, M A

    1998-03-01

    Based on results of simulation and empirical studies conducted within the Divisions of Biometrics, Center for Drug Evaluation and Research, Food and Drug Administration, and in collaboration with the National Toxicology Program, the Center has recently changed the significance levels for testing positive linear trend in incidence rate for common and rare tumors, respectively, from 0.01 and 0.05 to 0.005 and 0.025. The overall false positive rate resulting from the use of this new rule in the tests for linear trend in a two-species-two-sex study is about 10%, the rate that is judged as the most appropriate in a regulatory setting by the Center. This paper describes two of the studies. PMID:9547425

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

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

  11. Local and large-scale influences on Swiss temperature trends 1959-2008

    NASA Astrophysics Data System (ADS)

    Ceppi, P.; Scherrer, S. C.; Fischer, A.; Appenzeller, C.

    2010-09-01

    Temperature is a key variable for monitoring global climate change. Here we perform a trend analysis of Swiss temperatures from 1959-2008, using a new 2x2 km gridded data set based on carefully homogenized ground observations from MeteoSwiss. The aim of this study is twofold: first, to discuss the spatial and altitudinal temperature trend characteristics in detail and second, to quantify the contribution of global, large-scale and local-scale effects to these trends. The seasonal trends are all positive and mostly significant with an annual average warming rate of 0.35°C/decade (~1.6 times the global warming rate), ranging from 0.17 in autumn to 0.48°C/decade in summer. Altitude-dependent trends are found in autumn and early winter where the trends are stronger at low altitudes (<800 m asl), and in spring where slightly stronger trends are found at altitudes close to the snow line. The corresponding seasonal trends from the ENSEMBLES project regional climate models are weaker (~0.2°C/decade for all seasons) and show somewhat different patterns of altitude dependence. A large fraction of the trends can be explained by fluctuations in atmospheric circulation patterns, but with substantial differences from season to season. In winter, the magnitude and vertical distribution of the trends are reproduced accurately using large-scale and regional circulation dynamics effects only, while ~30-45% of the trends remain unexplained in spring and summer. In autumn, the mean trend is roughly reproduced but the altitudinal differences remain unexplained. This suggests that local effects are important to explain part of recent temperature trends in spring, summer and autumn. Snow-albedo feedback effects could be responsible for the 5-10% higher spring trends at altitudes close to the snow line. In autumn, the observed decrease in fog frequency might be a key process in explaining the stronger temperature trends at low altitudes.

  12. Assessing the impact of satellite-based observations in sea surface temperature trends

    NASA Astrophysics Data System (ADS)

    Huang, Boyin; Liu, Chunying; Banzon, Viva F.; Zhang, Huai-Min; Karl, Thomas R.; Lawrimore, Jay H.; Vose, Russell S.

    2016-04-01

    Global trends of sea surface temperature (SST) are assessed for the existing and new experimental SST analyses that incorporate advanced very high resolution radiometer (AVHRR) observations from NOAA polar-orbiting satellites. These analyses show that globally and annually averaged SST trends over the 21st century (2000-2015) are similar to the trends for the full satellite record period (1982-2015), regardless of whether AVHRR data are included in the analyses. It is shown that appropriate bias correction is an important step to remove discontinuities of AVHRR data for consistent time series and trend analysis.

  13. The variability of extreme temperatures and their relationship with atmospheric circulation: the contribution of applying linear and quadratic models

    NASA Astrophysics Data System (ADS)

    Savić, Stevan; Milovanović, Boško; Lužanin, Zorana; Lazić, Lazar; Dolinaj, Dragan

    2015-08-01

    This paper presents an analysis of the homogenised mean maximum ( T max) and minimum ( T min) temperatures. The data used in the analysis were collected at eight stations in the Autonomous Province of Vojvodina (Serbia) during the 1949-2008 period. The trends obtained from the slopes of the regression lines using the least square method show 0.9 °C/60 years for T max and 1.1 °C/60 years for T min; the non-parametric Mann-Kendall test was used to determine the statistically significant increasing trends of these two extreme parameters. In this paper, we analyse the influence of the Vangengeim-Girs classification of atmospheric circulation on the T max and T min trends in the Autonomous Province of Vojvodina (Serbia) using linear and quadratic models based on the least square method. Linear stepwise regression and the forward method reveal the highest dependence of T max and T min when the W or E circulation types are included in the model. Non-linear models show a greater contribution of T max and T min at W, E and C circulation types, respectively. The correction of the variance contribution of quadratic models ranges from approximately 16 to 44 % for T max and 32 to 38 % for T min.

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

    PubMed Central

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

    1989-01-01

    Median motor and sensory nerves were examined in 20 healthy subjects. Superficial stimulating and recording electrodes were used, and the nerves were examined at natural skin temperature, after cooling and after heating of the arm. The conduction velocity for the fastest and slow conducting sensory fibres (temperature range 17-37 degrees C), and for the fastest conducting motor fibres (temperature range 19-38 degrees C) increased non-linearly with increase in skin temperature. Similarly, distal motor latencies increased non-linearly with decrease in skin temperature. The effect of temperature was most pronounced in the low temperature range, and change in conduction velocity per degree centigrade was reduced toward higher skin temperature. Sensory nerve response duration increased linearly with decline in skin temperature. Sensory and motor amplitude did not show any significant relation to skin temperature. PMID:2738592

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

    USGS Publications Warehouse

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

    2002-01-01

    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

  16. Sulphate and desertification signals in Middle Eastern temperature trends

    SciTech Connect

    Nasrallah, H.A.; Balling, R.C. Jr.

    1994-12-31

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

  17. Multi-decadal Surface Temperature Trends and Extremes at Arctic Stations

    NASA Astrophysics Data System (ADS)

    Uttal, T.; Makshtas, A.

    2015-12-01

    The Arctic region is considered to be one where global temperatures are changing the most quickly; a number of factors make it the region where an accurate determination of surface temperature is the most difficult to measure or estimate. In developing a pan-Arctic perspective on Arctic in-situ temperature variability, several issues must be addressed including accounting for the different lengths of temperature records at different locations when comparing trends, accounting for the steep latitudinal controls on 'seasonal' trends, considering the often significant variability between different (sometimes a multitude) of temperature measurements made in the vicinity of a single station, and loss of detail information when data is ingested in a global archives or interpolated into gridded data sets. The International Arctic Systems for Observing the Atmosphere (www.iasoa.org) is an internationally networked consortium of facilities that measure a wide range of meteorological and climate relevant parameters; temperature is the most fundamental of these parameters. Many of the observatories have the longest temperature records in the Arctic region including Barrow, Alaska (114 years), Tiksi, Russia (83 years), and Eureka, Canada (67 years). Using the IASOA data sets a detailed analysis is presented of temperature trends presented as a function of the beginning date from which the trend is calculated, seasonal trends considered in the context of the extreme Arctic solar ephemeris, and the variability in occurrence of annual extreme temperature events. At the Tiksi observatory, a complete record is available of 3-hourly temperatures 1932 to present that was constructed through digitization of decades of written records. This data set is used to investigate if calculated trends and variabilities are consistent with those calculated from daily minimum and maximum values archived by the NOAA National Centers for Environmental Information Global Historical Climatology

  18. Establishing Long-Term Temperature Trends in California Amidst Data Set Variations

    NASA Astrophysics Data System (ADS)

    Wang, K.; Lettenmaier, D. P.; Williams, P.

    2015-12-01

    Close attention is being paid to California's water resources amidst drought conditions including the Sierra Nevada snow pack depth. Warm conditions and warm winters contribute to reduced winter snow accumulations. We examine long-term trends (1920-2015) of average daily maximum (Tmax) and minimum (Tmin) temperature as estimated by different long-term records, specifically: a) UCLA's West Coast Surface Water Monitor (SWM), b) the Parameter-Elevation Regression on Independent Slopes Model (PRISM), c) the Berkeley Earth Surface Temperature (BEST), and c) the National Climatic Data Center's (NCDC) (VOSE) data set. We also examine climatological values for Tmax and Tmin as estimated by Livneh et al. (J Clim., 2013) and Maurer et al. (J Clim., 2002) as these are related to the SWM gridded data set. We draw on station data from the U.S. Hydroclimatic Network (HCN) and the U.S. Cooperative Observer Network (COOP) and the temperatures published by NCDC as made available via ncdc.noaa.gov/cag/time-series/us for comparison. Within each data set, Tmin has stronger uptrends than Tmax. For both Tmin and Tmax, all but one of the data sets have increasing (mostly statistically significant) trends. Minimum winter temperature trends range from 1.3-1.8 C/100 years across the state; maximum winter temperature trends range from near zero to 1.0 C/100 years. Maps of trend magnitudes at the grid cell level show a surprising lack of agreement in spatial pattern likely due to differences in how each data set was constructed. Some data sets show nearly uniform trends due to the use of spatial smoothing, while others show highly varied local trends. We evaluate differences among the data sets in the stations used, periods of record, and gridding algorithms in an attempt to account for the variations in inferred temperature trends.

  19. Coatings for high-temperature structural materials: Trends and opportunities

    SciTech Connect

    1996-12-31

    This book assesses the state of the art of coatings materials and processes for gas-turbine blades and vanes, determines potential applications of coatings in high-temperature environments, identifies needs for improved coatings in terms of performance enhancements, design considerations, and fabrication processes, assesses durability of advanced coating systems in expected service environments, and discusses the required inspection, repair, and maintenance methods. The promising areas for research and development of materials and processes for improved coating systems and the approaches to increased coating standardization are identified, with an emphasis on materials and processes with the potential for improved performance, quality, reproducibility, or manufacturing cost reduction.

  20. Detection of trends in days with extreme temperatures in Iran from 1961 to 2010

    NASA Astrophysics Data System (ADS)

    Araghi, Alireza; Mousavi-Baygi, Mohammad; Adamowski, Jan

    2015-05-01

    Human health and comfort, crop productivity, water resource availability, as well as other critical hydrological, climatological, and ecological parameters are heavily influenced by trends in daily temperature maxima and minima (T d max, T d min, respectively). Using Mann-Kendall and sequential Mann-Kendall tests, trends in the number of days when T d max ≥ 30 °C or T d min ≤ 0 °C, over the period of 1961 to 2010, were examined for 30 synoptic meteorological stations in Iran. For 67 % of stations, days when T d min ≤ 0 °C showed a significant negative trend, while only 40 % of stations showed a significant positive trend in days when T d max ≥ 30 °C. The upward trend in T d max became significant between 1967 and 1975, according to the station, while the downward trend in T d min became significant between 1962 and 1974 for the same stations. Changes in precipitation type across most parts of the country show a high correlation with these temperature trends, especially with the negative trend in T d min. This suggests that future climatological and hydrological alterations within the country, along with ensuing climatic issues (e.g., change in precipitation, drought, etc.) will require a great deal more attention.

  1. Detection of trends in days with extreme temperatures in Iran from 1961 to 2010

    NASA Astrophysics Data System (ADS)

    Araghi, Alireza; Mousavi-Baygi, Mohammad; Adamowski, Jan

    2016-07-01

    Human health and comfort, crop productivity, water resource availability, as well as other critical hydrological, climatological, and ecological parameters are heavily influenced by trends in daily temperature maxima and minima ( T d max, T d min, respectively). Using Mann-Kendall and sequential Mann-Kendall tests, trends in the number of days when T d max ≥ 30 °C or T d min ≤ 0 °C, over the period of 1961 to 2010, were examined for 30 synoptic meteorological stations in Iran. For 67 % of stations, days when T d min ≤ 0 °C showed a significant negative trend, while only 40 % of stations showed a significant positive trend in days when T d max ≥ 30 °C. The upward trend in T d max became significant between 1967 and 1975, according to the station, while the downward trend in T d min became significant between 1962 and 1974 for the same stations. Changes in precipitation type across most parts of the country show a high correlation with these temperature trends, especially with the negative trend in T d min. This suggests that future climatological and hydrological alterations within the country, along with ensuing climatic issues (e.g., change in precipitation, drought, etc.) will require a great deal more attention.

  2. Increasing positive trend in the Antarctic sea ice extent and associated surface temperature changes

    NASA Astrophysics Data System (ADS)

    Comiso, J. C.

    2015-12-01

    The maximum extent of the Antarctic sea ice in 2014 was more than 20 x 106 km2 which is likely the highest during the satellite era. The updated historical record of the sea ice cover, as derived from multichannel passive microwave data, now shows a trend of 2.05 ± 0.18% per decade and 2.70 ± 0.20 % per decade for ice extent and ice area, respectively. This indicates not only a continuation of the positive trend but also a slight increase in the trends reported previously. A newly enhanced sea ice concentration data actually yield slightly more modest trends in the sea ice extent and ice area of 1.55 ± 0.17 % per decade and 2.40 ± 0.20 % per decade, respectively. The difference is mainly due to an improved matching of calibrations in the enhanced data for the different satellite sensors that provide the historical time series. The updated data also show regional shifts in the trends with a decrease in the positive trend in the Ross Sea, a decrease in the negative trend in the Bellingshausen/Amundsen Seas, and an increase in the positive trend in the other sectors. Such shifts undermine the previous hypothesis that the positive trend of Antarctic sea ice is primarily caused by increases in ice production in the Ross Sea. On the other hand, it is observed that surface temperatures for the same period, as derived from satellite data, show a general cooling in areas near the ice margin. Surface temperatures are also shown to be highly correlated with the extent of the sea ice cover. Such results suggests that the assimilation of satellite surface temperature data in numerical climate models may be needed to improve the performance of these models and enable better agreements with the observed trends of sea ice in the Southern Hemisphere.

  3. Linear and nonlinear effects of dominant drivers on the trends in global and regional land carbon uptake: 1959 to 2013

    NASA Astrophysics Data System (ADS)

    Zhang, Xuanze; Rayner, Peter J.; Wang, Ying-Ping; Silver, Jeremy D.; Lu, Xingjie; Pak, Bernard; Zheng, Xiaogu

    2016-02-01

    Changes in atmospheric CO2 levels, surface temperature, or precipitation have been identified to have significantly contributed to the estimated increase in the terrestrial carbon uptake rate over the last few decades; however, those analyses did not consider the interactions. Using the Australian community land surface model (Community Atmosphere Biosphere Land Exchange), we performed factorial experiments to quantify the importance of external drivers (climate drivers and atmospheric CO2) and their interactions on annual terrestrial carbon uptake (FL), excluding land use change and fires, from 1959 to 2013. Our model simulations show a trend of 0.025 ± 0.015 Pg C yr-2 (or ~1.5% yr-1) in global FL for 1959-2013, which is largely attributed to the positive influences of the increased atmospheric CO2 (0.050 ± 0.001 Pg C yr-2) and negative influences of changes in climate (-0.026 ± 0.014 Pg C yr-2). Globally, the contribution of the nonlinear effects of dominant drivers to the simulated trend in FL is small (<10%) but can be significant regionally (>35%), particularly in the boreal forests and semiarid regions. The interactions between temperature and CO2 or temperature and precipitation can dominate the simulated trend in parts of Europe, southeastern North America, southern China, and some semiarid regions. This modeling result suggests that the effects of nonlinear interactions of drivers on the trend of land carbon uptake should be considered in future studies.

  4. Using daily temperature to predict phenology trends in spring flowers

    NASA Astrophysics Data System (ADS)

    Kim, Jin-Hee; Kim, Soo-Ock; Kim, Dae-Jun; Moon, Kyung Hwan; Yun, Jin I.

    2015-05-01

    The spring season in Korea features a dynamic landscape with a variety of flowers blooming sequentially one after another. This enables local governments to earn substantial sightseeing revenues by hosting festivals featuring spring flowers. Furthermore, beekeepers move from the southern tip of the Korean Peninsula all the way northward in a quest to secure spring flowers as nectar sources for a sustained period of time. However, areal differences in flowering dates of flower species are narrowing, which has economic consequences. Analysis of data on flowering dates of forsythia ( Forsythia koreana) and cherry blossom ( Prunus serrulata), two typical spring flower species, as observed for the past 60 years at six weather stations of the Korea Meteorological Administration (KMA) indicated that the difference between the flowering date of forsythia, the earliest blooming flower in spring, and cherry blossom, which flowers later than forsythia, was 14 days on average in the climatological normal year for the period 1951-1980, compared with 11 days for the period 1981-2010. In 2014, the gap narrowed further to 7 days, making it possible in some locations to see forsythias and cherry blossoms blooming at the same time. Synchronized flowering of these two flower species is due to acceleration of flowering due to an abnormally high spring temperature, and this was more pronounced in the later-blooming cherry blossom than forsythia. While cherry blossom flowering dates across the nation ranged from March 31 to April 19 (an areal difference of 20 days) for the 1951-1980 normal year, the difference ranged from March 29 to April 12 (an areal difference of 16 days) for the 1981-2010 normal year, and in 2014, the flowering dates spanned March 25 and March 30 (an areal difference of 6 days). In the case of forsythia, the gap was narrower than in cherry blossoms. Climate change in the Korean Peninsula, reflected by rapid temperature hikes in late spring in contrast to a slow

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

    NASA Astrophysics Data System (ADS)

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

    2008-02-01

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

  6. First approach to the relationship between recent landscape changes and temperature trends in Spanish mainland

    NASA Astrophysics Data System (ADS)

    Lopez Escolano, Carlos; Peña-Angulo, Dhais; Salinas-Solé, Celia; Pueyo Campos, Angel; Brunetti, Miquele; Gonzalez-Hidalgo, Jose Carlos

    2016-04-01

    The recent analyses of monthly and seasonal Spanish mainland temperatures (1951-2010) at high spatial resolution using the MOTEDAS dataset shown that the monthly mean temperature values of maximum (Tmax) have risen mostly in late winter/early spring and the summer months, while the monthly mean temperature of minimum (Tmin) values have increased in summer, spring and autumn in southern areas. Consequently, a north-south gradient in diurnal temperature range (DTR) has been detected in summer months, with positive trends in the north and negative trends in the south, and negative pattern was found in the southeast in spring and autumn. During the same period, the Spanish mainland has suffered dramatic changes in the landscape related to urban and industrial sprawl, transportation infrastructures development, or the extension of irrigated areas for intensive agriculture. Those changes would be consistent with factors that affect Tmin, which are conditioned by the nature of the surfaces. In this research, we present the first approach to the relationship of temperature trend and landscapes changes at high spatial resolution in the Spanish mainland. Thus, we have compared the spatial distribution of temperature trend with changes in accessibility index and population potential simultaneously, and its spatial redistribution as indicator of landscape changes. The significance of temperature trends was evaluated by Mann-Kendal test, and its intensity by Seńs estimator. A mix model of population potential and accessibility index weighted by route factor has been used to assess landscape changes. Crosstab analysis was applied to identify the association between temperature trends and accessibility changes.

  7. 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

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

    2012-01-01

    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.

  8. The effect of wind on long-term summer water temperature trends in Tokyo Bay, Japan

    NASA Astrophysics Data System (ADS)

    Lu, Li-Feng; Onishi, Ryo; Takahashi, Keiko

    2015-06-01

    The effect of wind on summer water temperature trends in a semi-closed bay (Tokyo Bay, Japan) is examined through several numerical experiments using a high-resolution three-dimensional ocean model. The model is executed under no-wind and uniform southerly/northerly wind conditions, and monthly mean currents and temperature distributions and heat transport in Tokyo Bay for July are calculated. The model results show that wind has a significant effect on heat transport and temperature distribution in the bay. (1) When a southerly wind prevails northward cool water transport intensifies while southward warm water transport declines, thus decreasing the water temperature in the central bay area while increasing temperature at the bay head. (2) A northerly wind has an opposing effect and decreases the water temperature in coastal bay head area while increase the temperature along the southwest coast. The results also suggest that the trend of increasing southerly wind amplitude may have affected water temperature trends in Tokyo Bay from 1979 to 1997. The model results demonstrated that the an intensified southerly wind lowers water temperatures in most areas of the bay by enhancing upwelling and open ocean-water intrusion near the bay mouth while increases temperatures in the bottom layer of the bay head by suppressing southward warm water transport.

  9. Monitoring variability in trends of temperature and rainfall in the Apennine Alps (Middle Italy)

    NASA Astrophysics Data System (ADS)

    D'Aprile, Fabrizio; Tapper, Nigel

    2016-04-01

    In 2006 the School of Geography and Environmental Sciences of Monash University in collaboration with the Italian Forest Corps (Corpo Forestale dello Stato), Uffici Territoriali per la Biodiversità di Vallombrosa (Florence) and Pratovecchio (Arezzo)started to monitor the variability in temperature and rainfall in the Tuscan Apennine Alps (Middle Italy). First results showed unexpected variability in trends of both the climate variables and in particular very high variability in similarity of trends among sites even at short distance. Although the time series are ultra-centenary in some sites, trends in temperature and rainfall at the monthly level would show a reduction in temperature and increase in rainfall in the last decade in some cases. This uncertainty poses the question whether the phenomenon was due to some anomaly in the periodical oscillations of 6-7 years of length (spectral Fourier analysis) or the dominant trends in variability of monthly temperature and monthly rainfall are unchanged. Recent analysis of trends would confirm warming and drying of climate in the Apennine Alps in Middle Italy; however, in some sites a relative cooling is shown in the 2000s. In the area, climate warming appears to reach levels that may have relevant implications for forest composition and shift. The relatively fast increase in temperature and reduction in rainfall during the last 3-4 decades further strengthens the importance to continue monitoring climate variability to a deeper level and extend the understanding of its effects at the local level.

  10. Simulation of secular temperature trends in the stratosphere, mesosphere and lower thermosphere

    NASA Astrophysics Data System (ADS)

    Garcia, R. R.

    2014-12-01

    Anthropogenic emissions of greenhouse gases (GHG) warm the troposphere and cool the upper layers of the atmosphere above about 100 hPa. The pattern of temperature change with altitude depends, not just on the rate of emission of GHG, but also on changes in ozone brought about by decreases in the halogen burden of the atmosphere and by the changing temperature itself. We use the Whole Atmosphere Community Climate Model (WACCM) to investigate secular trends in temperature over the last 30 years and to project these changes into the rest of the 21st century. We compare model results against observations and show that WACCM reproduces many details of the observed trends, including the region of small or insignificant temperature trends near the mesopause; these changes may be understood in terms of the interplay among GHG, ozone, temperature, and the global circulation. The vertical profile of the temperature trend changes substantially in the course of the 21st century compared to the last 30 years as ozone responds to the curtailment of halogen emissions and as changing temperatures modify its photochemical equilibrium concentration.

  11. Arctic temperature trends from the early nineteenth century to the present

    NASA Astrophysics Data System (ADS)

    van Wijngaarden, W. A.

    2015-11-01

    Temperatures were examined at 118 stations located in the Arctic and compared to observations at 50 European stations whose records averaged 200 years and in a few cases extend to the early 1700s. Nearly all stations exhibited warming trends. For each station, the temperature relative to the average value during 1961-1990 was found. The resulting temperature change averaged over the Arctic stations was plotted. For the period 1820-2014, trends were found for the January, July and annual temperatures of 1.0, 0.0 and 0.7 °C per century, respectively. Decadal variations are evident and much of the temperature increase occurred during the 1990s. Over the past century, Siberia, Alaska and Western Canada have experienced somewhat greater warming than Eastern Canada, Greenland and Northern Europe. The temperature change experienced by the Arctic stations during the last two centuries closely tracks that found for the European stations.

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

    NASA Astrophysics Data System (ADS)

    Beig, Gufran

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

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

  14. Trends in record-breaking temperatures for the conterminous United States

    NASA Astrophysics Data System (ADS)

    Rowe, Clinton M.; Derry, Logan E.

    2012-08-01

    In an unchanging climate, record-breaking temperatures are expected to decrease in frequency over time, as established records become increasingly more difficult to surpass. This inherent trend in the number of record-breaking events confounds the interpretation of actual trends in the presence of any underlying climate change. Here, a simple technique to remove the inherent trend is introduced so that any remaining trend can be examined separately for evidence of a climate change. As this technique does not use the standard definition of a broken record, our records* are differentiated by an asterisk. Results for the period 1961-2010 indicate that the number of record* low daily minimum temperatures has been significantly and steadily decreasing nearly everywhere across the United States while the number of record* high daily minimum temperatures has been predominantly increasing. Trends in record* low and record* high daily maximum temperatures are generally weaker and more spatially mixed in sign. These results are consistent with other studies examining changes expected in a warming climate.

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

    NASA Astrophysics Data System (ADS)

    Kanno, Hitoshi; Soga, Makoto; Kajiwara, Kazuhito

    2007-08-01

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

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

    NASA Astrophysics Data System (ADS)

    Jo, Y.; Yan, X.

    2013-05-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Tayanç, Mete; Karaca, Mehmet; Yenigün, Orhan

    1997-01-01

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

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

    NASA Astrophysics Data System (ADS)

    NuñEz, Mario N.; Ciapessoni, HéCtor H.; Rolla, Alfredo; Kalnay, Eugenia; Cai, Ming

    2008-03-01

    The "observation minus reanalysis" (OMR) method has been used to estimate the impact of changes in land use (including urbanization and agricultural practices such as irrigation) by computing the difference between the trends of the surface observations (which reflect all the sources of climate forcing, including surface effects) and the NCEP/NCAR reanalysis (which only contains the forcings influencing the assimilated atmospheric trends). In this paper we apply the OMR method to surface stations in Argentina for the period 1961-2000. In contrast to most other land areas, over most of Argentina there has been net cooling, not warming (about -0.04°C/decade). Observations also show a very strong decrease in the diurnal temperature range north of 40°S. This is associated with an observed strong reduction in the maximum temperature (-0.12°C/decade) together with a weak warming trend in the minimum temperature (0.05°C/decade). The OMR trends show a warming contribution to the mean temperature (+0.07°C/decade) and a decrease in diurnal temperature range (-0.08°C/decade), especially strong in the areas where the observed precipitation has increased the most and where, as a consequence, there has been an exponential increase of soy production in the last decade. The increase in precipitation is apparently associated with an increase in the moisture transport from the Amazons to northern Argentina by the low-level jet.

  19. Temperature trends and extremes from long climatological records at Barrow, Alaska and Tiksi, Russia

    NASA Astrophysics Data System (ADS)

    Uttal, Taneil; Makshtas, Alexander

    2016-04-01

    In the International Arctic Systems for Observing the Atmosphere (www.IASOA.org) Barrow Alaska and Tiksi, Russia are sites with two of the longest climatological records dating from 1901 and 1936 respectively. Tiksi and Barrow are also particularly useful sites for comparing Arctic regional variability because they are located at nearly the same latitude (71.325 N and 71.596 N respectively). When making comparison of temperature trends and extremes, this fortunate coincidence allows elimination of the annual variability of incoming solar irradiance as one of the major factors controlling the variability of temperature when considering annual, seasonal, interannual and decadal changes. Although temperature is one of the most basic of environmental parameters measured globally on a routine basis, acquiring temperature records for analysis requires making choices about sources which may apply different quality control and averaging protocols affecting calculations especially of extremes. Records are available from the U.S. NOAA National Climatic Data Center and the Climate Research Unit of the U.K. Met Office. In addition, historical data rescue digitized data sets for Tiksi are available from the Russian Arctic and Antarctic Research Institute. Using these records a detailed analysis and comparison of temperature trends and extremes is performed. The temperature trends are examined using unique method whereby the variation of the trend itself is examined as a function of start year. Differences in statistics of extremes is examined for average, minimum and maximum temperatures. The trends and extremes are then compared between Barrow and Tiksi to determine if it is possible make a first order determination of relationships to larger scale circulation patterns.

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

    PubMed

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

    2012-02-01

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

  1. Contribution of changes in atmospheric circulation patterns to extreme temperature trends.

    PubMed

    Horton, Daniel E; Johnson, Nathaniel C; Singh, Deepti; Swain, Daniel L; Rajaratnam, Bala; Diffenbaugh, Noah S

    2015-06-25

    Surface weather conditions are closely governed by the large-scale circulation of the Earth's atmosphere. Recent increases in the occurrence of some extreme weather phenomena have led to multiple mechanistic hypotheses linking changes in atmospheric circulation to increasing probability of extreme events. However, observed evidence of long-term change in atmospheric circulation remains inconclusive. Here we identify statistically significant trends in the occurrence of atmospheric circulation patterns, which partially explain observed trends in surface temperature extremes over seven mid-latitude regions of the Northern Hemisphere. Using self-organizing map cluster analysis, we detect robust circulation pattern trends in a subset of these regions during both the satellite observation era (1979-2013) and the recent period of rapid Arctic sea-ice decline (1990-2013). Particularly substantial influences include the contribution of increasing trends in anticyclonic circulations to summer and autumn hot extremes over portions of Eurasia and North America, and the contribution of increasing trends in northerly flow to winter cold extremes over central Asia. Our results indicate that although a substantial portion of the observed change in extreme temperature occurrence has resulted from regional- and global-scale thermodynamic changes, the risk of extreme temperatures over some regions has also been altered by recent changes in the frequency, persistence and maximum duration of regional circulation patterns. PMID:26108856

  2. Spatial and temporal analysis of rainfall and temperature trend of India

    NASA Astrophysics Data System (ADS)

    Mondal, Arun; Khare, Deepak; Kundu, Sananda

    2015-10-01

    Climate change is a serious issue resulting in global variation in the temperature and precipitation pattern. In this study, changes in rainfall trend in India for 141 years (1871-2011) and temperature trend for 107 years (1901-2007) were analysed. The annual, seasonal and monthly changes in different regions of India were investigated to see the climate change in different parts of the country, and the net excess or deficit of rainfall and temperature in India was obtained. Statistical non-parametric tests were performed to see the trend magnitude with the Mann-Kendall (MK) test and Sen's slope. Mann-Whitney-Pettitt (MWP) test was used for probable break point detection in the series, and change percentage was calculated over 30 sub-divisions and 7 broad regions. The results indicate decreasing annual and monsoon rainfall of India in most of the sub-divisions, and temperature fluctuations were observed in all the places. Temperatures (minimum, maximum and mean) were showing a significant increase, particularly in the winter and post-monsoon time. Wide variation was noticed all over India in the case of the minimum temperature. Variation was also observed at different spatial scales of sub-divisions and regions. This study gives the net impact of climate change in India which shows net excess of temperature and net deficit of rainfall.

  3. Effect of Recent Sea Surface Temperature Trends on the Springtime Cooling Trend of the Arctic Stratospheric Vortex

    NASA Astrophysics Data System (ADS)

    Garfinkel, Chaim; Oman, Luke; Hurwitz, Margaret

    2015-04-01

    The springtime Arctic polar vortex has cooled significantly over the satellite era, with consequences for ozone concentrations in the springtime transition season. The causes of this cooling trend are deduced by using comprehensive chemistry-climate model experiments. Approximately half of the satellite era early springtime cooling trend in the Arctic lower stratosphere was caused by changing sea surface temperatures (SSTs). An ensemble of experiments forced only by changing SSTs is compared to an ensemble of experiments in which both the observed SSTs and chemically- and radiatively-active trace species are changing. By comparing the two ensembles, it is shown that warming of Indian Ocean, North Pacific, and North Atlantic SSTs, and cooling of the tropical Pacific, have strongly contributed to recent polar stratospheric cooling in late winter and early spring, and to a weak polar stratospheric warming in early winter. When concentrations of ozone-depleting substances and greenhouse gases are fixed, polar ozone concentrations show a small but robust decline due to changing SSTs. Ozone changes are magnified in the presence of changing gas concentrations. The stratospheric changes can be understood by examining the tropospheric height and heat flux anomalies generated by the anomalous SSTs. Finally, recent SST changes have contributed to a decrease in the frequency of late winter stratospheric sudden warmings.

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    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.

  5. Interpreting differential temperature trends at the surface and in the lower troposphere

    PubMed

    Santer; Wigley; Gaffen; Bengtsson; Doutriaux; Boyle; Esch; Hnilo; Jones; Meehl; Roeckner; Taylor; Wehner

    2000-02-18

    Estimated global-scale temperature trends at Earth's surface (as recorded by thermometers) and in the lower troposphere (as monitored by satellites) diverge by up to 0.14 degrees C per decade over the period 1979 to 1998. Accounting for differences in the spatial coverage of satellite and surface measurements reduces this differential, but still leaves a statistically significant residual of roughly 0.1 degrees C per decade. Natural internal climate variability alone, as simulated in three state-of-the-art coupled atmosphere-ocean models, cannot completely explain this residual trend difference. A model forced by a combination of anthropogenic factors and volcanic aerosols yields surface-troposphere temperature trend differences closest to those observed. PMID:10678823

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

    NASA Technical Reports Server (NTRS)

    Dunkerton, Timothy J.

    2000-01-01

    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.

  7. Tempo-spatial characteristics of sub-daily temperature trends in mainland China

    NASA Astrophysics Data System (ADS)

    Ren, Yuyu; Parker, David; Ren, Guoyu; Dunn, Robert

    2016-05-01

    The spatial and temporal pattern of sub-daily temperature change in mainland China was analysed for the period from 1973 to 2011 using a 3-hourly dataset based on 408 stations. The increase in surface air temperature was more significant by night between 1973 and 1992, with the fastest upward trend around local midnight being about 0.27 °C/decade, while it was more significant by day between 1992 and 2011, with the fastest upward trend being about 0.46 °C/decade in mid-late morning. The season with rapid temperature increase also shifted from winter in 1973-1992 (the largest increase happened near midnight in December, 0.75 °C/decade) to spring in 1992-2011 (the largest increase happened at in the early afternoon in March, 0.82 °C/decade). The change in the spatial distributions of the sub-daily temperature trends shows that Northeast China warmed more significantly in 1973-1992 than elsewhere, but it cooled in 1992-2011, when Southwest China was the new focus of temperature increase whereas it had previously been cooling. A preliminary analysis of the possible causes implies that changes in solar radiation, cloud cover, aerosols and the observational environments near the stations might have contributed to these observed temperature changes.

  8. Emerging trends in heavy precipitation and hot temperature extremes in Switzerland

    NASA Astrophysics Data System (ADS)

    Scherrer, S. C.; Fischer, E. M.; Posselt, R.; Liniger, M. A.; Croci-Maspoli, M.; Knutti, R.

    2016-03-01

    Changes in intensity and frequency of daily heavy precipitation and hot temperature extremes are analyzed in Swiss observations for the years 1901-2014/2015. A spatial pooling of temperature and precipitation stations is applied to analyze the emergence of trends. Over 90% of the series show increases in heavy precipitation intensity, expressed as annual maximum daily precipitation (mean change: +10.4% 100 years-1; 31% significant, p < 0.05) and in heavy precipitation frequency, expressed as the number of events greater than the 99th percentile of daily precipitation (mean change: +26.5% 100 years-1; 35% significant, p < 0.05). The intensity of heavy precipitation increases on average by 7.7% K-1 smoothed Swiss annual mean temperature, a value close to the Clausius-Clapeyron scaling. The hottest day and week of the year have warmed by 1.6 K to 2.3 K depending on the region, while the Swiss annual mean temperature increased by 1.9 K. The frequency of very hot days exceeding the 99th percentile of daily maximum temperature has more than tripled. Despite considerable local internal variability, increasing trends in heavy precipitation and hot temperature extremes are now found at most Swiss stations. The identified trends are unlikely to be random and are consistent with climate model projections, with theoretical understanding of a human-induced change in the energy budget and water cycle and with detection and attribution studies of extremes on larger scales.

  9. The role of aerosol in producing non-linear trends in CMIP5 historical simulations

    NASA Astrophysics Data System (ADS)

    Highwood, Ellie; Wilcox, Laura

    2013-04-01

    Variations in aerosol emissions have been implicated in producing variability on decadal timescales in the global temperature record. In this study, we apply the technique of Ensemble Empirical Mode Decomposition (EEMD) to the historical simulations from the CMIP5 models. Those that include a representation of the indirect effect of aerosol more closely reproduce historical global-mean near-surface temperatures, particularly the cooling in the 1950s and 1960s, compared to models with only a representation of the direct effect. Analysis of the available single forcing runs shows that this cooling is the result of a combination of natural and anthropogenic aerosol forcing. Models with the indirect effect also show a more pronounced decrease in precipitation in this period. This demonstrates the importance of representing aerosol, and their indirect effects, in general circulation models. We also discuss issues raised by the diversity of aerosol load and interactions in the CMIP5 models.

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  11. Diurnal temperature range trend over North Carolina and the associated mechanisms

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

    This study seeks to investigate the variability and presence of trend in the diurnal surface air temperature range (DTR) over North Carolina (NC) for the period 1950-2009. The significance trend test and the magnitude of trends were determined using the non-parametric Mann-Kendall test and the Theil-Sen approach, respectively. Statewide significant trends (p < 0.05) of decreasing DTR were found in all seasons and annually during the analysis period. Highest (lowest) temporal DTR trends of magnitude - 0.19 (- 0.031) °C/decade were found in summer (winter). Potential mechanisms for the presence/absence of trend in DTR have been highlighted. Historical data sets of the three main moisture components (precipitation, total cloud cover (TCC), and soil moisture) and the two major atmospheric circulation modes (North Atlantic Oscillation and Southern Oscillation) were used for correlation analysis. The DTRs were found to be negatively correlated with the precipitation, TCC and soil moisture across the state for all the seasons and annual basis. It appears that the moisture components related better to the DTR than to the atmospheric circulation modes.

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

    USGS Publications Warehouse

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

    2011-01-01

    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.

  13. The Summertime Warming Trends in Surface Water Temperature of the Great Lakes

    NASA Astrophysics Data System (ADS)

    Sugiyama, N.; Kravtsov, S.; Roebber, P.

    2014-12-01

    Over the past 30 years, the Laurentian Great Lakes have exhibited summertime warming trends in surface water temperature which were greater than those in surface air temperature of the surrounding land, by as much as an order of magnitude over some of the regions. For the years 1995-2012, Lake Superior exhibited the most dramatic warming trend in July-mean temperature, of 0.27±0.15 deg. C yr-1, based on the NOAA's GLSEA satellite observations. Shallower lakes, such as Lake Erie, exhibited smaller warming trends. In addition, within each lake, the warming was also the greatest in the regions of larger water depth; for example, some regions of Lake Superior deeper than 200m exhibited surface-water July-mean warming trends which exceeded 0.3 deg. C yr-1. We used a three-column lake model based on the one developed by Hostetler and Barnstein (1990) coupled with a two-layer atmospheric energy balance model to explore the physics behind these warming trends. We found that, as suggested by Austin and Colman (2007), the ice-albedo feedback plays an important role in amplifying the overlake warming trends. Our particular emphasis was on the question of whether the ice-albedo feedback alone is enough to account for lacustrine amplification of surface warming observed over the Great Lakes region. We found that the answer to this question depends on a number of model parameters, including the diffusion and light attenuation coefficients, which greatly affect the model's skill in reproducing the observed ice coverage of the deep lakes.

  14. Spatial distribution of temperature trends and extremes over Maharashtra and Karnataka States of India

    NASA Astrophysics Data System (ADS)

    Dhorde, Amit G.; Korade, Mahendra S.; Dhorde, Anargha A.

    2016-07-01

    Earth surface temperatures are changing worldwide together with the changes in the extreme temperatures. The present study investigates trends and variations of monthly maximum and minimum temperatures and their effects on seasonal fluctuations at different climatological stations of Maharashtra and Karnataka states of India. Trend analysis was performed on annual and seasonal mean maximum temperature (TMAX) and mean minimum temperature (TMIN) for the period 1969 to 2006. During the last 38 years, an increase in annual TMAX and TMIN has occurred. At most of the locations, the increase in TMAX was faster than the TMIN, resulting in an increase in diurnal temperature range. At the same time, annual mean temperature (TM) showed a significant increase over the study area. Percentiles were used to identify extreme temperature indices. An increase in occurrence of warm extremes was observed at southern locations, and cold extremes increased over the central and northeastern part of the study area. Occurrences of cold wave conditions have decreased rapidly compared to heat wave conditions.

  15. Combined land/sea surface-air-temperature trends, 1949-1972

    SciTech Connect

    Chen, R.S.

    1982-04-01

    A major deficiency in most previous studies of fluctuations in the earth's climate based on air temperature records has been the dearth of data from oceanic areas and the Southern Hemisphere. This study analyzes a unique collection of ship-based observations of surface air temperature assembled by the UK Meteorological Office in parallel with the station-based dataset developed by the National Center for Atmospheric Research from the publications World Weather Records and Monthly Climatic Data for the World. Based on this much more geographically comprehensive database, it is concluded that, during the 24-year period 1949 to 1972, no statistically significant warming or cooling trends were evident in the time series of globally averaged surface air temperature measurements. However, temperature trends did vary latitudinally, with significant cooling in northern extra-tropical latitudes, no trend in equatorial latitudes, and significant but not homogeneous warming in southern extra-tropical latitudes. Time series of air temperatures over land and sea exhibited qualitatively similar behavior over the period 1949 to 1972, indicative of both the comparable quality of the two datasets and the probable lack of significant widespread bias in the land-based measurements due to urban development. The results of this study underscore the need for dense and geographically comprehensive measurements from both land and ocean areas and from both hemispheres in analyzing the global behavior of the earth's climate.

  16. Uncovering Local Trends in Genetic Effects of Multiple Phenotypes via Functional Linear Models.

    PubMed

    Vsevolozhskaya, Olga A; Zaykin, Dmitri V; Barondess, David A; Tong, Xiaoren; Jadhav, Sneha; Lu, Qing

    2016-04-01

    Recent technological advances equipped researchers with capabilities that go beyond traditional genotyping of loci known to be polymorphic in a general population. Genetic sequences of study participants can now be assessed directly. This capability removed technology-driven bias toward scoring predominantly common polymorphisms and let researchers reveal a wealth of rare and sample-specific variants. Although the relative contributions of rare and common polymorphisms to trait variation are being debated, researchers are faced with the need for new statistical tools for simultaneous evaluation of all variants within a region. Several research groups demonstrated flexibility and good statistical power of the functional linear model approach. In this work we extend previous developments to allow inclusion of multiple traits and adjustment for additional covariates. Our functional approach is unique in that it provides a nuanced depiction of effects and interactions for the variables in the model by representing them as curves varying over a genetic region. We demonstrate flexibility and competitive power of our approach by contrasting its performance with commonly used statistical tools and illustrate its potential for discovery and characterization of genetic architecture of complex traits using sequencing data from the Dallas Heart Study. PMID:27027515

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    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.

  18. Air- and Stream-Water-Temperature Trends in the Chesapeake Bay Region, 1960-2014

    USGS Publications Warehouse

    Jastram, John D.; Rice, Karen C.

    2015-01-01

    The U.S. Environmental Protection Agency (EPA) uses indicators that “represent the state or trend of certain environmental or societal conditions … to track and better understand the effects of changes in the Earth’s climate” (U.S. Environmental Protection Agency, 2014). Updates to these indicators are published biennially by the EPA. The U.S. Geological Survey (USGS), in cooperation with the EPA, has completed analyses of air- and stream-water-temperature trends in the Chesapeake Bay region to be included as an indicator in a future release of the EPA report.

  19. Temperature trends and variability in the Greater Horn of Africa: interactions with precipitation

    NASA Astrophysics Data System (ADS)

    Camberlin, Pierre

    2016-03-01

    Relationships between daily precipitation and daily maximum and minimum temperature (Tx and Tn, respectively) are analyzed at station level over the Greater Horn of Africa (GHA). Rainfall occurrence is associated with either above normal Tn (mostly in cool highland areas) or below normal Tn (especially lowland, hot environments and early parts of the rainy season). Tx generally displays a more consistent response to rainfall occurrence, with cooling peaking 1 day after the rainfall event. However there is often a persistence of this cooling several days after the rainfall event, and the amplitude of the cooling is also greater for heavy rainfall events. These temperature anomalies are thought to be a response to cloudiness (concurrent reduced Tx and concurrent enhanced Tn) and soil moisture (reduced Tx and Tn, suggested to reflect evaporative cooling). These relationships are of relevance to the interpretation of temperature trends. From 1973 to 2013, the GHA shows a clear warming signal, for both Tn (+0.20 to +0.25 °C/decade depending on seasons) and Tx (+0.17 to +0.22 °C/decade). Rainfall shows both negative (mostly between February and July) and positive trends (mostly in October-December). Given the superimposition of temperature and rainfall trends in parts of the GHA and the covariations between daily rainfall and both Tx and Tn, regression models are used to extract the rainfall influence on temperature, accounting for lag effects up to 4 days. The daily residuals from these models are used to depict temperature variations independent from precipitation variations. At some stations, trends computed on these residuals noticeably differ from the raw Tx trends. When averaged across the GHA, these effects do not exceed -0.06 to +0.03 °C/decade (depending on the month) for Tx, and are marginal for Tn, thus do not strongly modify the magnitude of the warming in the last 40 years. Nevertheless, these results show that precipitation-temperature relationships must

  20. Land use/land cover change effects on temperature trends at U.S. Climate Normals stations

    USGS Publications Warehouse

    Hale, R.C.; Gallo, K.P.; Owen, T.W.; Loveland, T.R.

    2006-01-01

    Alterations in land use/land cover (LULC) in areas near meteorological observation stations can influence the measurement of climatological variables such as temperature. Urbanization near climate stations has been the focus of considerable research attention, however conversions between non-urban LULC classes may also have an impact. In this study, trends of minimum, maximum, and average temperature at 366 U.S. Climate Normals stations are analyzed based on changes in LULC defined by the U.S. Land Cover Trends Project. Results indicate relatively few significant temperature trends before periods of greatest LULC change, and these are generally evenly divided between warming and cooling trends. In contrast, after the period of greatest LULC change was observed, 95% of the stations that exhibited significant trends (minimum, maximum, or mean temperature) displayed warming trends. Copyriht 2006 by the American Geophysical Union.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    A series of localized ultrahigh-temperature (UHT)/high-temperature (HT) granulite facies regions have been identified within the regional amphibolite facies metamorphic zone of the Central Maine Terrane stretching from north-central New Hampshire, through central Massachusetts, and into northeastern Connecticut. Here, we aim to constrain the age and peak temperature of metamorphism at three localities within this region: Bristol, NH, Phillipston, MA and Willington, CT. Garnet-forming reactions are linked directly to peak metamorphic temperatures through thermodynamic modeling and/or Zr-in-rutile thermometry. Precise garnet geochronology allows us to identify the timing of these peak temperatures, as well as the duration of garnet growth. Geochronologic and thermodynamic work was done on 12 samples collected throughout a ~5 km2 metamorphic 'hotspot' previously identified in Bristol, NH (Chamberlain and Rumble, 1988; Journal of Petrology). The highest temperature assemblage within this hotspot is characterized by the presence of garnet + sillimanite + K-feldspar + cordierite and reached temperatures >820οC. The lowest temperature periphery of the hotspot is characterized by sillimanite + muscovite + K-feldspar + minor garnet and reached a maximum temperature of 650οC. Bulk garnet ages from samples within the hotspot range significantly from at least 400.0 × 2.5 Ma to 352.7 × 1.8 Ma with the youngest ages associated with the lower temperature samples. This collection of ages indicates a prolonged period (~50 Ma) of >650οC temperatures interspersed by period(s) of garnet growth. Zoned garnet geochronology will help reveal whether garnet growth and related heating was continuous or episodic. Further south, in Phillipston, MA, zoned garnet geochronology performed on a 2.5 cm diameter garnet porphyroblast indicates garnet growth spanning 389 - 363 Ma, reaching peak temperatures at the end of that time span of 920-940οC, followed by a younger event recorded in

  2. Ozone and temperature decadal trends in the stratosphere, mesosphere and lower thermosphere, based on measurements from SABER on TIMED

    NASA Astrophysics Data System (ADS)

    Huang, F. T.; Mayr, H. G.; Russell, J. M., III; Mlynczak, M. G.

    2014-08-01

    We have derived ozone and temperature trends from years 2002 through 2012, from 20 to 100 km altitude, and 48° S to 48° N latitude, based on measurements from the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on the Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics (TIMED) satellite. For the first time, trends of ozone and temperature measured at the same times and locations are obtained, and their correlations should provide useful information about the relative importance of photochemistry versus dynamics over the longer term. We are not aware of comparable results covering this time period and spatial extent. For stratospheric ozone, until the late 1990s, previous studies found negative trends (decreasing amounts). In recent years, some empirical and modeling studies have shown the occurrence of a turnaround in the decreasing ozone, possibly beginning in the late 1990s, suggesting that the stratospheric ozone trend is leveling off or even turning positive. Our global results add more definitive evidence, expand the coverage, and show that at mid-latitudes (north and south) in the stratosphere, the ozone trends are indeed positive, with ozone having increased by a few percent from 2002 through 2012. However, in the tropics, we find negative ozone trends between 25 and 50 km. For stratospheric temperatures, the trends are mostly negatively correlated to the ozone trends. The temperature trends are positive in the tropics between 30 and 40 km, and between 20 and 25 km, at approximately 24° N and at 24° S latitude. The stratospheric temperature trends are otherwise mostly negative. In the mesosphere, the ozone trends are mostly flat, with suggestions of small positive trends at lower latitudes. The temperature trends in this region are mostly negative, showing decreases of up to ~ -3 K decade-1. In the lower thermosphere (between ~ 85 and 100 km), ozone and temperature trends are both negative. The ozone trend can

  3. Trends in intra- and inter-annual temperature variabilities across Sudan.

    PubMed

    Elagib, Nadir Ahmed

    2010-01-01

    Four mean temperature variables, namely maximum (MAX), minimum (MIN), mean (MEAN) and diurnal temperature range (DTR), were considered for 14 selected observational stations throughout Sudan. The objectives were to investigate the seasonal and annual regimes, the seasonal and annual trends, the intra-annual variability (IAV) by the coefficient of variation (CV), and the interrelationships between the temperature variables and percent of possible sunshine. A mounting evidence of daytime and nighttime warming since the 1940s until 2005 is presented. The exception is the dry season which is dominated by daytime cooling attributable to the damping effect of dust haze/storms. Apparently, the progressive drought across inland locations has raised the MAXs, and to a lesser extent the MINs, of the wet season over those for the hot season. Accordingly, maximum rates of 0.451 and 0.336 degrees C decade(-1) were found for the nighttime and daytime temperatures, respectively. The extreme eastern and western locations have been frequently dominated by the warmest trend rates obtained nationwide. The prevalence of significant decreases (increases) of DTR is more apparent in the dry, hot and annual series (wet series). Depending on the temperature variable under consideration, many stations possessed significant trends toward either increased or decreased variability of the within-year monthly values, i.e. IAV. The correlation between the time series of annual CV and extreme values for each of the four temperature variables shows generally that warmer climate in Sudan is associated with higher intra-annual temperature variability and vise versa, i.e. the CV is directly correlated with the highest value within the year, but inversely correlated with the lowest one. The findings of this investigation also indicate that the DTR is directly related to percent of possible sunshine, but the relationship of the latter parameter is not so clear with MAX, MIN and MEAN. PMID:21053725

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

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

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

    NASA Technical Reports Server (NTRS)

    Remsberg, Ellis E.

    2007-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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

  7. What caused the recent ``Warm Arctic, Cold Continents'' trend pattern in winter temperatures?

    NASA Astrophysics Data System (ADS)

    Sun, Lantao; Perlwitz, Judith; Hoerling, Martin

    2016-05-01

    The emergence of rapid Arctic warming in recent decades has coincided with unusually cold winters over Northern Hemisphere continents. It has been speculated that this "Warm Arctic, Cold Continents" trend pattern is due to sea ice loss. Here we use multiple models to examine whether such a pattern is indeed forced by sea ice loss specifically and by anthropogenic forcing in general. While we show much of Arctic amplification in surface warming to result from sea ice loss, we find that neither sea ice loss nor anthropogenic forcing overall yield trends toward colder continental temperatures. An alternate explanation of the cooling is that it represents a strong articulation of internal atmospheric variability, evidence for which is derived from model data, and physical considerations. Sea ice loss impact on weather variability over the high-latitude continents is found, however, to be characterized by reduced daily temperature variability and fewer cold extremes.

  8. All-Digital Time-Domain CMOS Smart Temperature Sensor with On-Chip Linearity Enhancement

    PubMed Central

    Chen, Chun-Chi; Chen, Chao-Lieh; Lin, Yi

    2016-01-01

    This paper proposes the first all-digital on-chip linearity enhancement technique for improving the accuracy of the time-domain complementary metal-oxide semiconductor (CMOS) smart temperature sensor. To facilitate on-chip application and intellectual property reuse, an all-digital time-domain smart temperature sensor was implemented using 90 nm Field Programmable Gate Arrays (FPGAs). Although the inverter-based temperature sensor has a smaller circuit area and lower complexity, two-point calibration must be used to achieve an acceptable inaccuracy. With the help of a calibration circuit, the influence of process variations was reduced greatly for one-point calibration support, reducing the test costs and time. However, the sensor response still exhibited a large curvature, which substantially affected the accuracy of the sensor. Thus, an on-chip linearity-enhanced circuit is proposed to linearize the curve and achieve a new linearity-enhanced output. The sensor was implemented on eight different Xilinx FPGA using 118 slices per sensor in each FPGA to demonstrate the benefits of the linearization. Compared with the unlinearized version, the maximal inaccuracy of the linearized version decreased from 5 °C to 2.5 °C after one-point calibration in a range of −20 °C to 100 °C. The sensor consumed 95 μW using 1 kSa/s. The proposed linearity enhancement technique significantly improves temperature sensing accuracy, avoiding costly curvature compensation while it is fully synthesizable for future Very Large Scale Integration (VLSI) system. PMID:26840316

  9. All-Digital Time-Domain CMOS Smart Temperature Sensor with On-Chip Linearity Enhancement.

    PubMed

    Chen, Chun-Chi; Chen, Chao-Lieh; Lin, Yi

    2016-01-01

    This paper proposes the first all-digital on-chip linearity enhancement technique for improving the accuracy of the time-domain complementary metal-oxide semiconductor (CMOS) smart temperature sensor. To facilitate on-chip application and intellectual property reuse, an all-digital time-domain smart temperature sensor was implemented using 90 nm Field Programmable Gate Arrays (FPGAs). Although the inverter-based temperature sensor has a smaller circuit area and lower complexity, two-point calibration must be used to achieve an acceptable inaccuracy. With the help of a calibration circuit, the influence of process variations was reduced greatly for one-point calibration support, reducing the test costs and time. However, the sensor response still exhibited a large curvature, which substantially affected the accuracy of the sensor. Thus, an on-chip linearity-enhanced circuit is proposed to linearize the curve and achieve a new linearity-enhanced output. The sensor was implemented on eight different Xilinx FPGA using 118 slices per sensor in each FPGA to demonstrate the benefits of the linearization. Compared with the unlinearized version, the maximal inaccuracy of the linearized version decreased from 5 °C to 2.5 °C after one-point calibration in a range of -20 °C to 100 °C. The sensor consumed 95 μW using 1 kSa/s. The proposed linearity enhancement technique significantly improves temperature sensing accuracy, avoiding costly curvature compensation while it is fully synthesizable for future Very Large Scale Integration (VLSI) system. PMID:26840316

  10. 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)

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

    2014-10-01

    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.

  11. 21st Century Trends in Antarctic Temperature and Polar Stratospheric Cloud (PSC) Area in the GEOS Chemistry-Climate Model

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

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

  12. Circumpolar Dynamics of Arctic Tundra Vegetation in Relation to Temperature Trends

    NASA Astrophysics Data System (ADS)

    Epstein, H. E.; Bhatt, U. S.; Raynolds, M. K.; Walker, D. A.; Reichle, L.

    2015-12-01

    Arctic tundra vegetation has generally exhibited a "greening" trend for at least the past three decades. However, these temporal trends in tundra vegetation are highly heterogeneous in space across different arctic regions, as well as showing variability over time. The factors controlling this variability are likely numerous with complex interactions, however, a first approach is to examine how vegetation dynamics relate to trends in temperature. We used a 32-year record (1982-2013) of the Normalized Difference Vegetation Index (NDVI) and Land Surface Temperatures from Advanced Very High Resolution Radiometer (AVHRR) sensors onboard NOAA satellites (GIMMS 3g dataset) to analyze observed changes in both aboveground tundra vegetation and surface temperatures. We divided the circumpolar dataset into two continental regions (North America and Eurasia), as well as by tundra subzone (A-E) sensu the Circumpolar Arctic Vegetation Map (CAVM). We 1) compared temporal trends in both MaxNDVI (peak values) and TI-NDVI (seasonally integrated values) with those of the Summer Warmth Index (SWI - sum of mean monthly temperatures > 0 °C); 2) assessed how the detrended interannual variabilities in NDVI compared to those of SWI; and 3) analyzed current and prior year SWI, as well as prior year NDVI, as controls on current year NDVI. Interannual coefficients of variation for SWI were 2.0 - 2.5 times greater than those for NDVI, and the temporal trendlines for NDVI were much "tighter" with greater r² values than those for SWI. Interannual variability in NDVI was greatest in the "Mid-Low" Arctic, whereas interannual variability in SWI was greatest in the most southern Arctic. Surprisingly, the observed relative rates of change in NDVI were greater than those of SWI for the warmer subzones for both North America and Eurasia. Finally, the change in NDVI from one year to the next was only weakly correlated with current year SWI. These results suggest that 1) there are clearly factors

  13. On the interannual variability and on trends of the temperature in the middle atmosphere

    NASA Astrophysics Data System (ADS)

    Labitzke, K.; Naujokat, B.

    1985-07-01

    The new Reference Atmosphere presented here is based on global satellite data and forms a very useful basis for climatological studies. When using such climatologies it is important to be aware of the well known interannual variability which n themiddle atmosphere is particularly large during the northern winters and southern springs. Variability ofthe upper and lower stratospheres is discussed in detail. Areas covered included the polar region and the middile and lower latitudes. Temperature trends, notably the alteration of the global temperature structure by a number of anthropogenically influenced tract gases or the greenhouse effect is discussed.

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

    NASA Technical Reports Server (NTRS)

    Yang, Fanglin; Lau, K.-M.

    2004-01-01

    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

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

    SciTech Connect

    Tran Huu Phat; Nguyen Van Long; Nguyen Tuan Anh; Le Viet Hoa

    2008-11-15

    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.

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

    NASA Astrophysics Data System (ADS)

    Bian, Qiying; Lu, Riyu

    2013-04-01

    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.

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

    PubMed Central

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

    2013-01-01

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

  18. Linear dependence of surface expansion speed on initial plasma temperature in warm dense matter

    PubMed Central

    Bang, W.; Albright, B. J.; Bradley, P. A.; Vold, E. L.; Boettger, J. C.; Fernández, J. C.

    2016-01-01

    Recent progress in laser-driven quasi-monoenergetic ion beams enabled the production of uniformly heated warm dense matter. Matter heated rapidly with this technique is under extreme temperatures and pressures, and promptly expands outward. While the expansion speed of an ideal plasma is known to have a square-root dependence on temperature, computer simulations presented here show a linear dependence of expansion speed on initial plasma temperature in the warm dense matter regime. The expansion of uniformly heated 1–100 eV solid density gold foils was modeled with the RAGE radiation-hydrodynamics code, and the average surface expansion speed was found to increase linearly with temperature. The origin of this linear dependence is explained by comparing predictions from the SESAME equation-of-state tables with those from the ideal gas equation-of-state. These simulations offer useful insight into the expansion of warm dense matter and motivate the application of optical shadowgraphy for temperature measurement. PMID:27405664

  19. Linear dependence of surface expansion speed on initial plasma temperature in warm dense matter

    NASA Astrophysics Data System (ADS)

    Bang, W.; Albright, B. J.; Bradley, P. A.; Vold, E. L.; Boettger, J. C.; Fernández, J. C.

    2016-07-01

    Recent progress in laser-driven quasi-monoenergetic ion beams enabled the production of uniformly heated warm dense matter. Matter heated rapidly with this technique is under extreme temperatures and pressures, and promptly expands outward. While the expansion speed of an ideal plasma is known to have a square-root dependence on temperature, computer simulations presented here show a linear dependence of expansion speed on initial plasma temperature in the warm dense matter regime. The expansion of uniformly heated 1–100 eV solid density gold foils was modeled with the RAGE radiation-hydrodynamics code, and the average surface expansion speed was found to increase linearly with temperature. The origin of this linear dependence is explained by comparing predictions from the SESAME equation-of-state tables with those from the ideal gas equation-of-state. These simulations offer useful insight into the expansion of warm dense matter and motivate the application of optical shadowgraphy for temperature measurement.

  20. Linear dependence of surface expansion speed on initial plasma temperature in warm dense matter

    DOE PAGESBeta

    Bang, Woosuk; Albright, Brian James; Bradley, Paul Andrew; Vold, Erik Lehman; Boettger, Jonathan Carl; Fernández, Juan Carlos

    2016-07-12

    Recent progress in laser-driven quasi-monoenergetic ion beams enabled the production of uniformly heated warm dense matter. Matter heated rapidly with this technique is under extreme temperatures and pressures, and promptly expands outward. While the expansion speed of an ideal plasma is known to have a square-root dependence on temperature, computer simulations presented here show a linear dependence of expansion speed on initial plasma temperature in the warm dense matter regime. The expansion of uniformly heated 1–100 eV solid density gold foils was modeled with the RAGE radiation-hydrodynamics code, and the average surface expansion speed was found to increase linearly withmore » temperature. The origin of this linear dependence is explained by comparing predictions from the SESAME equation-of-state tables with those from the ideal gas equation-of-state. In conclusion, these simulations offer useful insight into the expansion of warm dense matter and motivate the application of optical shadowgraphy for temperature measurement.« less

  1. Linear dependence of surface expansion speed on initial plasma temperature in warm dense matter.

    PubMed

    Bang, W; Albright, B J; Bradley, P A; Vold, E L; Boettger, J C; Fernández, J C

    2016-01-01

    Recent progress in laser-driven quasi-monoenergetic ion beams enabled the production of uniformly heated warm dense matter. Matter heated rapidly with this technique is under extreme temperatures and pressures, and promptly expands outward. While the expansion speed of an ideal plasma is known to have a square-root dependence on temperature, computer simulations presented here show a linear dependence of expansion speed on initial plasma temperature in the warm dense matter regime. The expansion of uniformly heated 1-100 eV solid density gold foils was modeled with the RAGE radiation-hydrodynamics code, and the average surface expansion speed was found to increase linearly with temperature. The origin of this linear dependence is explained by comparing predictions from the SESAME equation-of-state tables with those from the ideal gas equation-of-state. These simulations offer useful insight into the expansion of warm dense matter and motivate the application of optical shadowgraphy for temperature measurement. PMID:27405664

  2. A Non-linear Temperature-Time Program for Non-isothermal Kinetic Measurements

    NASA Astrophysics Data System (ADS)

    Sohn, Hong Yong

    2016-04-01

    A new temperature-time program for non-isothermal measurements of chemical reaction rates has been developed. The major advantages of the proposed temperature-time function are twofold: Firstly, the analysis of kinetic information in the high temperature range of the measurement is improved over the conventional linear temperature program by slowing the rate of temperature increase in the high temperature range and secondly, the new temperature program greatly facilitates the data analysis by providing a closed-form solution of the temperature integral and allows a convenient way to obtain the kinetic parameters by eliminating the need for the approximate evaluation of the temperature integral. The procedures for applying the new temperature-time program to the analysis of experimental data are demonstrated in terms of the determination of the kinetic parameters based on the selection of a suitable conversion function in the rate equation as well as the direct determination of activation energy at different conversion extents without the need for a conversion function. The rate analysis based on the new temperature program is robust and does not appear to be sensitive to errors in experimental measurements.

  3. Trend analysis of air temperature time series in Greece and their relationship with circulation using surface and satellite data: recent trends and an update to 2013

    NASA Astrophysics Data System (ADS)

    Feidas, H.

    2016-07-01

    In this paper, the surface and lower tropospheric temperature trends in Greece and their relationship to the atmospheric circulation for the period 1955-2013 were examined, updating the study of Feidas et al. (Theor Appl Climatol 79:185-208, 2004) for data observed during the 12-year period 2002-2013. The trend analysis is based on a combination of three statistical tests. The trends are now examined for all the seasonal time series, new atmospheric circulation indices were added in the analysis, and maps with the spatial distribution of correlation between air temperature and atmospheric circulation were constructed and analysed. The series updated to 2013 for 18 stations reveal a clearer positive trend than that found for the period 1955-2001 on both the annual and the seasonal timescales. The warming signal detected only in summer in the study of Feidas et al. (Theor Appl Climatol 79:185-208, 2004) has now intensified and spread in other seasons. This warming appears to be mainly caused by the very high temperatures in the last decade (after 2004) of the record. At the national scale, there is now a match between surface temperature trends in Greece and Northern Hemisphere (NH) but only for summer, spring and annual time series, which are the only time series presenting a statistically significant warming trend in Greece. Satellite-induced lower tropospheric temperatures now show a statistically significant tropospheric temperature warming trend for the period 1979-2013, for both areas (Greece and NH). Lower tropospheric and surface air temperatures for the same period (1979-2013) show a very good agreement, with differences only in winter and summer for Greece. The influence of atmospheric circulation on the temperature variability in Greece was also examined using two more circulation indices: the Eastern Mediterranean Pattern Index (EMPI) and the North-Sea Caspian Pattern Index (NCPI). EMPI and especially NCPI explain better now the temperature variance in

  4. Interannual and decadal variability and trends in upper ocean temperatures in the North Pacific Ocean

    SciTech Connect

    White, W.B.; Cayan, D.R.

    1994-12-31

    Temperature profiles from the surface to 400 m deployed over the North Pacific Ocean for the 45 years from 1950--1994 are mapped onto a coarse grid each month, allowing trends in the upper ocean temperature to be estimated. Only temperature profiles distributed from 20{degree}N-60{degree}N are used, these subjected to rigorous scientific quality control. Two parameters are chosen to be representative of the upper ocean thermal structure; i.e., sea surface temperature (SST) and heat storage over the upper 400 m (HS400). Mapping of SST and HS400 is conducted monthly, with optimal interpolation utilizing a priori estimates of the covariance structure of the anomalous fields determined by White. This yields a time sequence of 540 monthly maps for each parameter over this 45-year period. Examining these time sequences for decadal variability and trends finds their magnitude and sign to change substantially as a function of geographical location over the North Pacific Ocean. For example, all along the west coast of North America, both SST and HS400 warmed during the past 45 years. But, in the middle of the North Pacific Ocean, both parameters cooled over this period. The average SST and HS400 over the entire domain from 20{degree}-60{degree}N did not show a trend. Rather, decadal variability dominated the time sequence, with the 1950`s colder than normal, the 1960`s near normal, the 1970`s warmer than normal, the 1980`s colder than normal, and the 1990`s warmer than normal. This natural decadal variability obscures any possible anthropogenic warming due to increased greenhouse gas concentrations in the atmosphere over this period.

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

    NASA Astrophysics Data System (ADS)

    Villazon, M. F.

    2013-05-01

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

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

    USGS Publications Warehouse

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

    2003-01-01

    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.

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

    SciTech Connect

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

    2009-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Shan, Ning; Wang, Zhijing; Liu, Xia

    2014-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-04-01

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

  11. Two-warehouse partial backlogging inventory model for deteriorating items with linear trend in demand under inflationary conditions

    NASA Astrophysics Data System (ADS)

    Jaggi, Chandra K.; Khanna, Aditi; Verma, Priyanka

    2011-07-01

    In today's business transactions, there are various reasons, namely, bulk purchase discounts, re-ordering costs, seasonality of products, inflation induced demand, etc., which force the buyer to order more than the warehouse capacity. Such situations call for additional storage space to store the excess units purchased. This additional storage space is typically a rented warehouse. Inflation plays a very interesting and significant role here: It increases the cost of goods. To safeguard from the rising prices, during the inflation regime, the organisation prefers to keep a higher inventory, thereby increasing the aggregate demand. This additional inventory needs additional storage space, which is facilitated by a rented warehouse. Ignoring the effects of the time value of money and inflation might yield misleading results. In this study, a two-warehouse inventory model with linear trend in demand under inflationary conditions having different rates of deterioration has been developed. Shortages at the owned warehouse are also allowed subject to partial backlogging. The solution methodology provided in the model helps to decide on the feasibility of renting a warehouse. Finally, findings have been illustrated with the help of numerical examples. Comprehensive sensitivity analysis has also been provided.

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

    SciTech Connect

    Antoniak, Z.I.

    1993-09-01

    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.

  13. Influence of temperature and precipitation variability on near-term snow trends

    NASA Astrophysics Data System (ADS)

    Mankin, Justin S.; Diffenbaugh, Noah S.

    2015-08-01

    Snow is a vital resource for a host of natural and human systems. Global warming is projected to drive widespread decreases in snow accumulation by the end of the century, potentially affecting water, food, and energy supplies, seasonal heat extremes, and wildfire risk. However, over the next few decades, when the planning and implementation of current adaptation responses are most relevant, the snow response is more uncertain, largely because of uncertainty in regional and local precipitation trends. We use a large (40-member) single-model ensemble climate model experiment to examine the influence of precipitation variability on the direction and magnitude of near-term Northern Hemisphere snow trends. We find that near-term uncertainty in the sign of regional precipitation change does not cascade into uncertainty in the sign of regional snow accumulation change. Rather, temperature increases drive statistically robust consistency in the sign of future near-term snow accumulation trends, with all regions exhibiting reductions in the fraction of precipitation falling as snow, along with mean decreases in late-season snow accumulation. However, internal variability does create uncertainty in the magnitude of hemispheric and regional snow changes, including uncertainty as large as 33 % of the baseline mean. In addition, within the 40-member ensemble, many mid-latitude grid points exhibit at least one realization with a statistically significant positive trend in net snow accumulation, and at least one realization with a statistically significant negative trend. These results suggest that the direction of near-term snow accumulation change is robust at the regional scale, but that internal variability can influence the magnitude and direction of snow accumulation changes at the local scale, even in areas that exhibit a high signal-to-noise ratio.

  14. Impact of sea surface temperature trend on late summer Asian rainfall in the twentieth century

    NASA Astrophysics Data System (ADS)

    Bian, Qiying; Lu, Riyu

    2013-05-01

    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, which are performed by the U. S. Climate Variability and Predictability 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 rain belt over East Asia. It is found that all of the models simulate an intensified WNP subtropical high (WNPSH) in late summer, an enhanced precipitation in the tropical Indian Ocean and the maritime continent, and a suppressed precipitation in the South Asian monsoon region, the South China Sea, and the Philippine Sea, 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. The warmer SST trend in the Indian Ocean and western Pacific may suppress precipitation over the Philippine Sea and thus result in a lower tropospheric anticyclonic circulation over the subtropical WNP. The warmer SSTs in the Indian Ocean may also be responsible for the anomalous easterlies and resultant less rainfall over the South Asian monsoon region. The precipitation changes forced by the SST trend are similar in the maritime continent but show an apparent difference over East Asia, in comparison with the observed rainfall trend over lands. The possible reasons for this difference are discussed.

  15. Commercial Development of an Advanced, High-Temperature, Linear-Fresnel Based Concentrating Solar Power Concept

    SciTech Connect

    Viljoen, Nolan; Schuknecht, Nathan

    2012-05-28

    Included herein is SkyFuel’s detailed assessment of the potential for a direct molten salt linear Fresnel collector. Linear Fresnel architecture is of interest because it has features that are well suited for use with molten salt as a heat transfer fluid: the receiver is fixed (only the mirrors track), the receiver diameter is large (reducing risk of freeze events), and the total linear feet of receiver can be reduced due to the large aperture area. Using molten salt as a heat transfer fluid increases the allowable operating temperature of a collector field, and the cost of thermal storage is reduced in proportion to that increase in temperature. At the conclusion of this project, SkyFuel determined that the cost goals set forth in the contract could not be reasonably met. The performance of a Linear Fresnel collector is significantly less than that of a parabolic trough, in particular due to linear Fresnel’s large optical cosine losses. On an annual basis, the performance is 20 to 30% below that of a parabolic trough per unit area. The linear Fresnel collector and balance of system costs resulted in an LCOE of approximately 9.9¢/kWhre. Recent work by SkyFuel has resulted in a large aperture trough design (DSP Trough) with an LCOE value of 8.9 ¢/kWhre calculated with comparative financial terms and balance of plant costs (White 2011). Thus, even though the optimized linear Fresnel collector of our design has a lower unit cost than our optimized trough, it cannot overcome the reduction in annual performance.

  16. Prediction of Nino 3 sea surface temperatures using linear inverse modeling

    SciTech Connect

    Penland, C.; Magorian, T. )

    1993-06-01

    Linear inverse modeling is used to predict sea surface temperatures (SSTs) in the Nino 3 region. Predictors in three geographical locations are used: the tropical Pacific Ocean, the tropical Pacific and Indian oceans, and the global tropical oceans. Predictions did not depend crucially on any of these three domains, and evidence was found to support the assumption that linear dynamics dominates most of the record. The prediction model performs better when SST anomalies are rapidly evolving than during warm events when large anomalies persist. The rms prediction error at a lead time of 9 months is about half a degree Celsius. 31 refs., 9 figs., 1 tab.

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

    USGS Publications Warehouse

    Friedel, Michael J.

    2012-01-01

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

  18. Recent temperature variability and trends in the coastal areas of the western Svalbard

    NASA Astrophysics Data System (ADS)

    Isaksen, Ketil; Nordli, Øyvind; Przybylak, Rajmund; Wyszynski, Przemyslaw

    2015-04-01

    The Svalbard Archipelago (74°-81°N, 10°-35°E) has experienced the greatest temperature increase in Europe during the latest three decades. Svalbard is also noted for its wide year-to-year variation in monthly temperatures and weather. The project "Arctic climate system study of ocean, sea ice and glaciers interactions in Svalbard area" (AWAKE-2) is a continuation and extension of the Polish-Norwegian AWAKE project (2009-2011). The aim of the AWAKE-2 is to understand the interactions between the main components of the climate system in the Svalbard area to identify mechanisms of interannual climate variability and long-term trends. The main hypothesis is that the Atlantic Water inflows over the Svalbard shelf and into the fjords have become more frequent during the last decades due to changes in the ocean and atmosphere. The integrated effect of these events results in new regimes and changes in atmosphere, ocean, sea ice and glaciers in Svalbard. Furthermore, changes in the cryosphere create feedback effects in ocean and atmosphere. One of the objectives in the AWAKE-2 project is to study atmospheric climate variability and trends in the coastal areas of the western Svalbard. In this study we analyse the recent temperature increase and temperature variability along the western coastal areas of Svalbard and compare this to the long-term variability based on historical data. Especially focus is given to the spatial and temporal air temperature gradients along western Svalbard. Changes in possible key factors controlling the recent large temperature anomalies are discussed.

  19. Trends in temperature extremes over nine integrated agricultural regions in China, 1961-2011

    NASA Astrophysics Data System (ADS)

    Wu, Xushu; Wang, Zhaoli; Zhou, Xiaowen; Lai, Chengguang; Chen, Xiaohong

    2016-06-01

    By characterizing the patterns of temperature extremes over nine integrated agricultural regions (IARs) in China from 1961 to 2011, this study performed trend analyses on 16 extreme temperature indices using a high-resolution (0.5° × 0.5°) daily gridded dataset and the Mann-Kendall method. The results show that annually, at both daytime and nighttime, cold extremes significantly decreased but warm extremes significantly increased across all IARs. Overall, nighttimes tended to warm faster than daytimes. Diurnal temperature ranges (DTR) diminished, apart from the mid-northern Southwest China Region and the mid-Loess Plateau Region. Seasonally, DTR widely diminished across all IARs during the four seasons except for spring. Higher minimum daily minimum temperature (TNn) and maximum daily maximum temperature (TXx), in both summer and winter, were recorded for most IARs except for the Huang-Huai-Hai Region; in autumn, all IARs generally encountered higher TNn and TXx. In all seasons, warming was observed at daytime and nighttime but, again, nighttimes warmed faster than daytimes. The results also indicate a more rapid warming trend in Northern and Western China than in Southern and Eastern China, with accelerated warming at high elevations. The increases in TNn and TXx might cause a reduction in agriculture yield in spring over Northern China, while such negative impact might occur in Southern China during summer. In autumn and winter, however, the negative impact possibly occurred in most of the IARs. Moreover, increased TXx in the Pearl River Delta and Yangtze River Delta is possibly related to rapid local urbanization. Climatically, the general increase in temperature extremes across Chinese IARs may be induced by strengthened Northern Hemisphere Subtropical High or weakened Northern Hemisphere Polar Vortex.

  20. Actual and future trends of extreme values of temperature for the NW Iberian Peninsula

    NASA Astrophysics Data System (ADS)

    Taboada, J.; Brands, S.; Lorenzo, N.

    2009-09-01

    It is now very well established that yearly averaged temperatures are increasing due to anthropogenic climate change. In the area of Galicia (NW Spain) this trend has also been determined. The main objective of this work is to assess actual and future trends of different extreme indices of temperature, which are of curcial importance for many impact studies. Station data for the study was provided by the CLIMA database of the regional government of Galicia (NW Spain). As direct GCM-output significantly underestimates the variance of daily surface temperature variables in NW Spain, these variables are obtained by applying a statistical downscaling technique (analog method), using 850hPa temperature and mean sea level pressure as combined predictors. The predictor fields have been extracted from three GCMs participating in the IPCC AR4 under A1, A1B and A2 scenarios. The definitions of the extreme indices have been taken from the joint CCl/CLIVAR/JCOMM Expert Team (ET) on Climate Change Detection and Indices (ETCCDI) This group has defined a set of standard extreme values to simplify intercomparisons of data from different regions of the world. For the temperatures in the period 1960-2006, results show a significant increase of the number of days with maximum temperatures above the 90th percentile. Furthermore, a significant decrease of the days with maximum temperatures below the 10th percentile has been found. The tendencies of minimum temperatures are reverse: less nights with minimum temperatures below 10th percentile, and more with minimum temperatures above 90th percentile. Those tendencies can be observed all over the year, but are more pronounced in summer. We have also calculated the relationship between the above mentioned extreme values and different teleconnection patterns appearing in the North Atlantic area. Results show that local tendencies are associated with trends of EA (Eastern Atlantic) and SCA (Scandinavian) patterns. NAO (North Atlantic

  1. A Linearization Time-Domain CMOS Smart Temperature Sensor Using a Curvature Compensation Oscillator

    PubMed Central

    Chen, Chun-Chi; Chen, Hao-Wen

    2013-01-01

    This paper presents an area-efficient time-domain CMOS smart temperature sensor using a curvature compensation oscillator for linearity enhancement with a −40 to 120 °C temperature range operability. The inverter-based smart temperature sensors can substantially reduce the cost and circuit complexity of integrated temperature sensors. However, a large curvature exists on the temperature-to-time transfer curve of the inverter-based delay line and results in poor linearity of the sensor output. For cost reduction and error improvement, a temperature-to-pulse generator composed of a ring oscillator and a time amplifier was used to generate a thermal sensing pulse with a sufficient width proportional to the absolute temperature (PTAT). Then, a simple but effective on-chip curvature compensation oscillator is proposed to simultaneously count and compensate the PTAT pulse with curvature for linearization. With such a simple structure, the proposed sensor possesses an extremely small area of 0.07 mm2 in a TSMC 0.35-μm CMOS 2P4M digital process. By using an oscillator-based scheme design, the proposed sensor achieves a fine resolution of 0.045 °C without significantly increasing the circuit area. With the curvature compensation, the inaccuracy of −1.2 to 0.2 °C is achieved in an operation range of −40 to 120 °C after two-point calibration for 14 packaged chips. The power consumption is measured as 23 μW at a sample rate of 10 samples/s. PMID:23989825

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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.

  4. Trends in temperature extremes in association with weather-intraseasonal fluctuations in eastern China

    NASA Astrophysics Data System (ADS)

    Qian, Cheng; Yan, Zhongwei; Wu, Zhaohua; Fu, Congbin; Tu, Kai

    2011-03-01

    Trends in the frequencies of four temperature extremes (the occurrence of warm days, cold days, warm nights and cold nights) with respect to a modulated annual cycle (MAC), and those associated exclusively with weather-intraseasonal fluctuations (WIF) in eastern China were investigated based on an updated homogenized daily maximum and minimum temperature dataset for 1960-2008. The Ensemble Empirical Mode Decomposition (EEMD) method was used to isolate the WIF, MAC, and longer-term components from the temperature series. The annual, winter and summer occurrences of warm (cold) nights were found to have increased (decreased) significantly almost everywhere, while those of warm (cold) days have increased (decreased) in northern China (north of 40°N). However, the four temperature extremes associated exclusively with WIF for winter have decreased almost everywhere, while those for summer have decreased in the north but increased in the south. These characteristics agree with changes in the amplitude of WIF. In particular, winter WIF of maximum temperature tended to weaken almost everywhere, especially in eastern coastal areas (by 10%-20%); summer WIF tended to intensify in southern China by 10%-20%. It is notable that in northern China, the occurrence of warm days has increased, even where that associated with WIF has decreased significantly. This suggests that the recent increasing frequency of warm extremes is due to a considerable rise in the mean temperature level, which surpasses the effect of the weakening weather fluctuations in northern China.

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

    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

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

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

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

  8. Temperature trends for reaction rates, hydrogen generation, and partitioning of iron during experimental serpentinization of olivine

    NASA Astrophysics Data System (ADS)

    McCollom, Thomas M.; Klein, Frieder; Robbins, Mark; Moskowitz, Bruce; Berquó, Thelma S.; Jöns, Niels; Bach, Wolfgang; Templeton, Alexis

    2016-05-01

    A series of laboratory experiments were conducted to examine how partitioning of Fe among solid reaction products and rates of H2 generation vary as a function of temperature during serpentinization of olivine. Individual experiments were conducted at temperatures ranging from 200 to 320 °C, with reaction times spanning a few days to over a year. The extent of reaction ranged from <1% to ∼23%. Inferred rates for serpentinization of olivine during the experiments were 50-80 times slower than older studies had reported but are consistent with more recent results, indicating that serpentinization may proceed more slowly than previously thought. Reaction products were dominated by chrysotile, brucite, and magnetite, with minor amounts of magnesite, dolomite, and iowaite. The chrysotile contained only small amounts of Fe (XFe = 0.03-0.05, with ∼25% present as ferric Fe in octahedral sites), and displayed little variation in composition with reaction temperature. Conversely, the Fe contents of brucite (XFe = 0.01-0.09) increased steadily with decreasing reaction temperature. Analysis of the reaction products indicated that the stoichiometry of the serpentinization reactions varied with temperature, but remained constant with increasing reaction progress at a given temperature. The observed distribution of Fe among the reaction products does not appear to be entirely consistent with existing equilibrium models of Fe partitioning during serpentinization, suggesting improved models that include kinetic factors or multiple reaction steps need to be developed. Rates of H2 generation increased steeply from 200 to 300 °C, but dropped off at higher temperatures. This trend in H2 generation rates is attributable to a combination of the overall rate of serpentinization reactions and increased partitioning of Fe into brucite rather than magnetite at lower temperatures. The results suggest that millimolal concentration of H2 could be attained in moderately hot hydrothermal

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  11. Trends in atmospheric patterns conducive to seasonal precipitation and temperature extremes in California.

    PubMed

    Swain, Daniel L; Horton, Daniel E; Singh, Deepti; Diffenbaugh, Noah S

    2016-04-01

    Recent evidence suggests that changes in atmospheric circulation have altered the probability of extreme climate events in the Northern Hemisphere. We investigate northeastern Pacific atmospheric circulation patterns that have historically (1949-2015) been associated with cool-season (October-May) precipitation and temperature extremes in California. We identify changes in occurrence of atmospheric circulation patterns by measuring the similarity of the cool-season atmospheric configuration that occurred in each year of the 1949-2015 period with the configuration that occurred during each of the five driest, wettest, warmest, and coolest years. Our analysis detects statistically significant changes in the occurrence of atmospheric patterns associated with seasonal precipitation and temperature extremes. We also find a robust increase in the magnitude and subseasonal persistence of the cool-season West Coast ridge, resulting in an amplification of the background state. Changes in both seasonal mean and extreme event configurations appear to be caused by a combination of spatially nonuniform thermal expansion of the atmosphere and reinforcing trends in the pattern of sea level pressure. In particular, both thermal expansion and sea level pressure trends contribute to a notable increase in anomalous northeastern Pacific ridging patterns similar to that observed during the 2012-2015 California drought. Collectively, our empirical findings suggest that the frequency of atmospheric conditions like those during California's most severely dry and hot years has increased in recent decades, but not necessarily at the expense of patterns associated with extremely wet years. PMID:27051876

  12. Trends in atmospheric patterns conducive to seasonal precipitation and temperature extremes in California

    PubMed Central

    Swain, Daniel L.; Horton, Daniel E.; Singh, Deepti; Diffenbaugh, Noah S.

    2016-01-01

    Recent evidence suggests that changes in atmospheric circulation have altered the probability of extreme climate events in the Northern Hemisphere. We investigate northeastern Pacific atmospheric circulation patterns that have historically (1949–2015) been associated with cool-season (October-May) precipitation and temperature extremes in California. We identify changes in occurrence of atmospheric circulation patterns by measuring the similarity of the cool-season atmospheric configuration that occurred in each year of the 1949–2015 period with the configuration that occurred during each of the five driest, wettest, warmest, and coolest years. Our analysis detects statistically significant changes in the occurrence of atmospheric patterns associated with seasonal precipitation and temperature extremes. We also find a robust increase in the magnitude and subseasonal persistence of the cool-season West Coast ridge, resulting in an amplification of the background state. Changes in both seasonal mean and extreme event configurations appear to be caused by a combination of spatially nonuniform thermal expansion of the atmosphere and reinforcing trends in the pattern of sea level pressure. In particular, both thermal expansion and sea level pressure trends contribute to a notable increase in anomalous northeastern Pacific ridging patterns similar to that observed during the 2012–2015 California drought. Collectively, our empirical findings suggest that the frequency of atmospheric conditions like those during California’s most severely dry and hot years has increased in recent decades, but not necessarily at the expense of patterns associated with extremely wet years. PMID:27051876

  13. Linear viscoelastic limits of asphalt concrete at low and intermediate temperatures

    NASA Astrophysics Data System (ADS)

    Mehta, Yusuf A.

    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

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

    PubMed Central

    Shi, Changzhi; Liu, Xiaowei; Chuai, Rongyan

    2009-01-01

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

  15. Piezoresistive sensitivity, linearity and resistance time drift of polysilicon nanofilms with different deposition temperatures.

    PubMed

    Shi, Changzhi; Liu, Xiaowei; Chuai, Rongyan

    2009-01-01

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

  16. Time series decomposition of remotely sensed land surface temperature and investigation of trends and seasonal variations in surface urban heat islands

    NASA Astrophysics Data System (ADS)

    Quan, Jinling; Zhan, Wenfeng; Chen, Yunhao; Wang, Mengjie; Wang, Jinfei

    2016-03-01

    Previous time series methods have difficulties in simultaneous characterization of seasonal, gradual, and abrupt changes of remotely sensed land surface temperature (LST). This study proposed a model to decompose LST time series into trend, seasonal, and noise components. The trend component indicates long-term climate change and land development and is described as a piecewise linear function with iterative breakpoint detection. The seasonal component illustrates annual insolation variations and is modeled as a sinusoidal function on the detrended data. This model is able to separate the seasonal variation in LST from the long-term (including gradual and abrupt) change. Model application to nighttime Moderate Resolution Imaging Spectroradiometer (MODIS)/LST time series during 2000-2012 over Beijing yielded an overall root-mean-square error of 1.62 K between the combination of the decomposed trend and seasonal components and the actual MODIS/LSTs. LST decreased (~ -0.086 K/yr, p < 0.1) in 53% of the study area, whereas it increased with breakpoints in 2009 (~0.084 K/yr before and ~0.245 K/yr after 2009) between the fifth and sixth ring roads. The decreasing trend was stronger over croplands than over urban lands (p < 0.05), resulting in an increasing trend in surface urban heat island intensity (SUHII, 0.022 ± 0.006 K/yr). This was mainly attributed to the trends in urban-rural differences in rainfall and albedo. The SUHII demonstrated a concave seasonal variation primarily due to the seasonal variations of urban-rural differences in temperature cooling rate (related to canyon structure, vegetation, and soil moisture) and surface heat dissipation (affected by humidity and wind).

  17. The regions with the most significant temperature trends during the last century

    NASA Astrophysics Data System (ADS)

    Zhaomei, Zeng; Zhongwei, Yan; Duzheng, Ye

    2001-07-01

    Having analyzed a global grid temperature anomaly data set and some sea level pressure data during the last century, we found the following facts. Firstly, the annual temperature change with a warming trend of about 0.6°C/ 100 years in the tropical area over Indian to the western Pacific Oceans was most closely correlated to the global mean change. Therefore, the temperature change in this area might serve as an indi-cator of global mean change at annual and longer time scales. Secondly, a cooling of about -0.3°C/ 100 years occurred over the northern Atlantic. Thirdly, a two-wave pattern of temperature change, warming over northern Asia and northwestern America and cooling over the northern Atlantic and the northern Pa-cific, occurred during the last half century linked to strengthening westerlies over the northern Atlantic and the weakening Siberian High. Fourthly, a remarkable seasonal difference occurred over the Eurasian con-tinent, with cooling (warming) in winter (summer) during 1896-1945, and warming (cooling) in winter (summer) during 1946-1995. The corresponding variations of the North Atlantic Oscillation and the South-ern Oscillation were also discussed.

  18. Analysis of trends in climate, streamflow, and stream temperature in north coastal California

    USGS Publications Warehouse

    Madej, M.A.

    2011-01-01

    As part of a broader project analyzing trends in climate, streamflow, vegetation, salmon, and ocean conditions in northern California national park units, we compiled average monthly air temperature and precipitation data from 73 climate stations, streamflow data from 21 river gaging stations, and limited stream temperature data from salmon-bearing rivers in north coastal California. Many climate stations show a statistically significant increase in both average maximum and average minimum air temperature in early fall and midwinter during the last century. Concurrently, average September precipitation has decreased. In many coastal rivers, summer low flow has decreased and summer stream temperatures have increased, which affects summer rearing habitat for salmonids. Nevertheless, because vegetative cover has also changed during this time period, we cannot ascribe streamflow changes to climate change without first assessing water budgets. Although shifts in the timing of the centroid of runoff have been documented in snowmelt-dominated watersheds in the western United States, this was not the case in lower elevation coastal rivers analyzed in this study.

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

    SciTech Connect

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

    2015-01-21

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

  20. Non-linear analysis of PESA-Lo electrostatic analyzer data and solar wind temperature anisotropies

    NASA Astrophysics Data System (ADS)

    Djordjevic, B. Z.; Maruca, B.; Bale, S. D.; Wilson, L. B., III; Larson, D. E.

    2015-12-01

    In this study, non-linear fitting techniques are applied to ion measurements from the Wind spacecraft's PESA-Lo electrostatic analyzer. Previous studies have relied primarily on moments-analyses, which, although satisfactory for simple distributions and density calculations, often return unreasonable values for higher order moments (e.g., temperature) and fail to account for non-thermal effects (e.g., temperature anisotropy and beams) and multiple ion-species. A Levenberg-Marquadt non-linear algorithm is applied to the PESA-Lo data in order to calculate the characteristic parameters of the proton, alpha-particle, and beam distributions. This analysis is augmented with calibration data from the WIND Faraday cups and magnetic-field data from WIND/MFI. Preliminary results from this non-linear analysis indicate that it indeed provides higher-quality ion parameters than the existing moments-analysis. When this analysis is complete, the set of bulk-parameter values will be suitable for studies of microinstabilities in the solar wind and of possible correlation between magnetic field fluctuations and non-thermal properties of the ion distributions. Applications of thermodynamic principles, such as the Boltzmann H-theorem, will allow for further characterization of the non-thermal properties of the solar wind.

  1. Split Stirling linear cryogenic cooler for high-temperature infrared sensors

    NASA Astrophysics Data System (ADS)

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

    2009-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

  4. Temperature effects on EPR spectra of a linear chain copper complex-copper calcium acetate hexahydrate

    NASA Astrophysics Data System (ADS)

    De, D. K.

    1981-03-01

    The observed angular dependence of the electron paramagnetic resonance linewidth in the ab and ac planes of CuCa(AC)2, 6H2O in the temperature interval 77K-12K was explained by considering dipolar interactions along with hyperfine and isotropic exchange interactions in these two planes. It was found that this so called linear-chain copper compound can be better described by a three dimensional paramagnet. The exchange interaction is very nearly isotropic with values Jab = 0.0098 cm-1 and Jc = 0.0103 cm-1. The values of the A⊥ derived from the linewidth fit in the ab plane are 14G at 77K and 60.5G at 1.2K. Due to insufficiency of data in the ac plane, the fit was done with the measured value of A∥. Although the exchange interaction has been found to be temperature independent the hyperfine interaction increases very much at low temperatures. The high temperature (300-460K) EPR spectra are quite different from the low temperature spectra. High temperature differential thermal analyses and thermogravimetric analyses have been carried out and corroborated with the EPR findings.

  5. Linear response to leadership, effective temperature and decision making in flocks

    NASA Astrophysics Data System (ADS)

    Pearce, Daniel; Giomi, Luca

    The Vicsek model is the prototypical system for studying collective behavior of interacting self propelled particles (SPPs). It has formed the basis for models explaining the collective behavior of many active systems including flocks of birds and swarms of insects. To the standard Vicsek model we introduce a small angular torque to a subset of the particles and observe how this effects the direction of polarisation of the entire swarm. This is analogous to a few informed birds trying to lead the rest of a large flock by initiating a turn. We find a linear response to this perturbation and fluctuations that are in agreement with fluctuation dissipation theorem. This allows the identification of an effective temperature for the Vicsek model that follows a power law with the noise amplitude. The linear response can also be extended to the process of decision-making, wherein flocks must decide between the behaviors of two competing subgroups of individuals.

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

    SciTech Connect

    Zakir, U.; Qamar, A.; Haque, Q.

    2013-05-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

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

    SciTech Connect

    Moradi, S.; Anderson, J.

    2012-08-15

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

    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).

  10. Effect of Recent Sea Surface Temperature Trends on the Arctic Stratospheric Vortex

    NASA Technical Reports Server (NTRS)

    Garfinkel, Chaim I.; Oman, Luke; Hurwitz, Margaret

    2015-01-01

    The springtime Arctic polar vortex has cooled significantly over the satellite era, with consequences for ozone concentrations in the springtime transition season. The causes of this cooling trend are deduced by using comprehensive chemistry-climate model experiments. Approximately half of the satellite era early springtime cooling trend in the Arctic lower stratosphere was caused by changing sea surface temperatures (SSTs). An ensemble of experiments forced only by changing SSTs is compared to an ensemble of experiments in which both the observed SSTs and chemically- and radiatively-active trace species are changing. By comparing the two ensembles, it is shown that warming of Indian Ocean, North Pacific, and North Atlantic SSTs, and cooling of the tropical Pacific, have strongly contributed to recent polar stratospheric cooling in late winter and early spring, and to a weak polar stratospheric warming in early winter. When concentrations of ozone-depleting substances and greenhouse gases are fixed, polar ozone concentrations show a small but robust decline due to changing SSTs. Ozone changes are magnified in the presence of changing gas concentrations. The stratospheric changes can be understood by examining the tropospheric height and heat flux anomalies generated by the anomalous SSTs. Finally, recent SST changes have contributed to a decrease in the frequency of late winter stratospheric sudden warmings.

  11. Karakorum temperature out of phase with hemispheric trends for the past five centuries

    NASA Astrophysics Data System (ADS)

    Zafar, Muhammad Usama; Ahmed, Moinuddin; Rao, Mukund Palat; Buckley, Brendan M.; Khan, Nasrullah; Wahab, Muhammad; Palmer, Jonathan

    2016-03-01

    A systematic increase in global temperature since the industrial revolution has been attributed to anthropogenic forcing. This increase has been especially evident over the Himalayas and Central Asia and is touted as a major contributing factor for glacier mass balance declines across much of this region. However, glaciers of Pakistan's Karakorum region have shown no such decline during this time period, and in some instances have exhibited slight advance. This discrepancy, known as the `Karakorum Anomaly', has been attributed to unusual amounts of debris covering the region's glaciers; the unique seasonality of the region's precipitation; and localized cooling resulting from increased cloudiness from monsoonal moisture. Here we present a tree-ring based reconstruction of summer (June-August) temperature from the Karakorum of North Pakistan that spans nearly five centuries (1523-2007 C.E.). The ring width indices are derived from seven collections (six— Picea smithiana and one— Pinus gerardiana) from middle-to-upper timberline sites in the northern Karakorum valleys of Gilgit and Hunza at elevations ranging from 2850 to 3300 meters above mean sea level (mean elevation 3059 m asl). The reconstruction passes all traditional calibration-verification schemes and explains 41 % of the variance of the nested Gilgit-Astore instrumental station data (Gilgit—1454 m asl, 1951-2009; Astore—2167 m asl, 1960-2013). Importantly, our results indicate that Karakorum temperature has remained decidedly out of phase with hemispheric temperature trends for at the least the past five centuries, highlighting the long-term stability of the Karakorum Anomaly, and suggesting that the region's temperature and cloudiness are contributing factors to the anomaly.

  12. Analysis of the change in temperature trends in Subansiri River basin for RCP scenarios using CMIP5 datasets

    NASA Astrophysics Data System (ADS)

    Shivam; Goyal, Manish Kumar; Sarma, Arup Kumar

    2016-06-01

    This study focuses on changes in the maximum and minimum temperature over the Subansiri River basin for different climate change scenarios. For the study, dataset from Intergovernmental Panel on Climate Change (IPCC) fifth assessment report (AR5) (i.e., coupled model intercomparison project phase five (CMIP5) dataset with representative concentration pathway (RCP) scenarios) were utilized. Long-term (2011-2100) maximum temperature (T max) and minimum temperature (Tmin) time series were generated using the statistical downscaling technique for low emission scenario (RCP2.6), moderate emission scenario (RCP6.0), and extreme emission scenario (RCP8.5). Trends and change of magnitude in T max, T min, and diurnal temperature range (DTR) were analyzed for different interdecadal time scales (2011-2100, 2011-2040, 2041-2070, 2070-2100) using Mann-Kendall non-parametric test and Sen's slope estimator, respectively. The temperature data series for the observed duration (1981-2000) has been found to show increasing trends in T max and T min at both annual and monthly scale. Trend analysis of downscaled temperature for the period 2011-2100 shows increase in annual maximum temperature and annual minimum temperature for all the selected RCP scenarios; however, on the monthly scale, T max and T min have been seen to have decreasing trends in some months.

  13. Crystallization Trends of PEO-b-PCL with Solvent and Temperature Effects

    NASA Astrophysics Data System (ADS)

    Allen, Kristi; Carandang, Allison; van Horn, Ryan

    There is a great deal of interest in being able to selectively modify properties of certain polymers. This increases the amount of control that can be exercised over end products in terms of the hydrophobicity or hydrophilicity, transparency, and brittleness and is highly valued in the biomedical industry. In this case, the crystallization trends of the diblock co-polymer poly(ethylene-oxide)-b-poly(ɛ-caprolactone) (PEO-b-PCL) were observed with the manipulation of solvent and drying temperatures in a variety of samples. The solvents utilized included tetrahydrofuran, chloroform, and toluene. The crystallized samples were scanned via infrared spectroscopy. Results showed highest amounts of PEO crystallization compared to PCL crystallization in toluene while the lowest values were seen in samples in tetrahydrofuran. The chloroform samples fell in the middle. Moderate differences were observed in different molecular weight samples.

  14. Multi-decadal variability and trends in the temperature of the northwest European continental shelf: A model-data synthesis

    NASA Astrophysics Data System (ADS)

    Holt, Jason; Hughes, Sarah; Hopkins, Joanne; Wakelin, Sarah L.; Penny Holliday, N.; Dye, Stephen; González-Pola, César; Hjøllo, Solfrid Sætre; Mork, Kjell Arne; Nolan, Glen; Proctor, Roger; Read, Jane; Shammon, Theresa; Sherwin, Toby; Smyth, Tim; Tattersall, Graham; Ward, Ben; Wiltshire, Karen Helen

    2012-11-01

    We examine the trends and variability in temperature of the northwest European shelf seas over the period 1960-2004 using four approaches: a regional model simulation (using the Proudman Oceanographic Laboratory Coastal Ocean Modelling System; POLCOMS), in situ multi-annual timeseries observations, satellite remote sensed (AVHRR) sea surface temperature (SST), and an analysis of data held in an international database at the International Council for the Exploration of the Sea (ICES). We focus on variability for the full period and trends from 1985 to 2004, being limited by the length of model simulation and the availability of satellite data. We find that all data sources give a consistent picture, with both trends and variability being intensified on-shelf and north of ∼48°N. The model and AVHRR SST show statistically significant warming trends in large areas of this region that are clearly distinguishable from both model/observation error and natural variability on these timescales. This ‘signal to noise ratio’ is substantially reduced when near bottom temperatures are considered in the model. The long timeseries at Port Erin (Isle of Man) shows that the variation in trend is well represented by the model and that the warming trend in the period 1985-2004 is substantially larger and of longer duration than previous peaks in 20-year trends since 1914. We find that the SST trends are greater in the model and satellite observations than the air temperature trends in the ERA40 re-analysis used for forcing; the net sea to air heat flux is ∼20% less in 1985-2004 than 1960-1984 (including shortwave, longwave, sensible and latent components). This is partly compensated by a ∼9% reduction in advective warming. The model shows the trends in seasonally stratified regions are greater at the surface than at depth, indicating an increase in this stratification. While this pattern is also seen in the annual trends from the ICES data analysis, the lack of seasonal

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

    The future survival of coral reefs depends on the envelope of critical climatic conditions determining the severity of impacts on the ecosystem. While coral health is strongly determined by extreme heat events, that lead to bleaching and often death, chronic "heat loading" may also disadvantage corals by making them more susceptible to, for example, diseases. On the other hand, it has been shown that coral living in hotter areas have higher bleaching thresholds and may be affected by less mortality at extreme events. This level at which heat anomalies lead to coral mortality varies widely across oceans, from ~31 deg C across the Caribbean to ~32 deg C in the Great Barrier Reef to 37.5 deg C in the Persian/Arabian Gulf. Thus, there clearly exists local adaptation and the extremes required to kill reefs strongly vary among regions. This could be be interpreted as suggesting that as long as bleaching temperatures are not reached, increased overall heat content expressed by a positive annual thermal anomaly, might actually foster coral resilience. Is there evidence for or against such an argument? Bleaching events have been occurring worldwide with variable recurrence and variable subsequent recovery. Despite demonstrated adaptation to higher-than-usual mean summer temperatures, reefs in the Arabian Gulf and the Red Sea are on a declining trajectory. This coincides with consistent warming in the region. Mean annual anomalies of ocean temperature (since 1870) and atmospheric temperatures (since 1950) increase throughout the region. Since 1994 (Red Sea) and 1998 (southern Arabian Gulf) all mean annual anomalies have been positive and this period has coincided with repeated, severe bleaching events. In the Eastern Pacific (Galapagos and Easter Island), the trend of mean annual temperature anomalies has been declining and coral cover has been increasing. Thus, trends in coral cover and mean annual anomaly are negatively correlated in both regions. Despite strong impacts

  16. Abundance trend with condensation temperature for stars with different Galactic birth places

    NASA Astrophysics Data System (ADS)

    Adibekyan, V.; Delgado-Mena, E.; Figueira, P.; Sousa, S. G.; Santos, N. C.; González Hernández, J. I.; Minchev, I.; Faria, J. P.; Israelian, G.; Harutyunyan, G.; Suárez-Andrés, L.; Hakobyan, A. A.

    2016-08-01

    Context. During the past decade, several studies reported a correlation between chemical abundances of stars and condensation temperature (also known as Tc trend). However, the real astrophysical nature of this correlation is still debated. Aims: The main goal of this work is to explore the possible dependence of the Tc trend on stellar Galactocentric distances, Rmean. Methods: We used high-quality spectra of about 40 stars observed with the HARPS and UVES spectrographs to derive precise stellar parameters, chemical abundances, and stellar ages. A differential line-by-line analysis was applied to achieve the highest possible precision in the chemical abundances. Results: We confirm previous results that [X/Fe] abundance ratios depend on stellar age and that for a given age, some elements also show a dependence on Rmean. When using the whole sample of stars, we observe a weak hint that the Tc trend depends on Rmean. The observed dependence is very complex and disappears when only stars with similar ages are considered. Conclusions: To conclude on the possible dependence of the Tc trend on the formation place of stars, a larger sample of stars with very similar atmospheric parameters and stellar ages observed at different Galactocentric distances is needed. Based on observations collected with the HARPS spectrograph at the 3.6-m telescope (program ID: 095.D-0717(A)), installed at the La Silla Observatory, ESO (Chile), with the UVES spectrograph at the 8-m Very Large Telescope (program ID: 095.D-0717(B)), installed at the Cerro Paranal Observatory, ESO (Chile). Also based on data obtained from the ESO Science Archive Facility under request numbers: vadibekyan180760, vadibekyan180762, vadibekyan180764, vadibekyan180768, vadibekyan180769, vadibekyan180771, vadibekyan180773, vadibekyan180778, and vadibekyan180779.Tables with stellar parameters and chemical abundances are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or

  17. Underestimation of oxygen deficiency hazard through use of linearized temperature profiles

    SciTech Connect

    Kerby, J.

    1989-06-15

    The failure mode analysis for any cryogenic system includes the effects of a large liquid spill due to vessel rupture or overfilling. The Oxygen Deficiency Hazard (ODH) analysis for this event is a strong function of the estimated heat flux entering the spilled liquid. A common method for estimating the heat flux is to treat the surface on which the liquid spills as a semi-infinite solid. This note addresses the effect of linearizing the temperature profile in this form of analysis, and shows it to cause the calculated flux to be underestimated by more than a factor of two. 3 refs., 2 figs.

  18. Study on The Response Improvement of A Linear Actuator Using Temperature-Sensitive Magnetic Material

    NASA Astrophysics Data System (ADS)

    Hirata, Katsuhiro; Kanzaki, Yasunori; Ota, Tomohiro; Yamaguchi, Tadashi; Kawase, Yoshihiro

    We have been studying a linear actuator for the thermostatic switch using temperature-sensitive magnetic material (TSMM). In this paper, the effect of the geometry of TSMM on response time is investigated by computing the dynamic characteristics of the actuator employing the 3-D finite element method coupled with the equations of magnetic field, heat transfer and motion. As a result, it is found that the response of the actuator is greatly improved. The validity of the computation is clarified though the comparison with the measurement of a prototype.

  19. Linear relation of central and eastern North American precipitation to tropical Pacific Sea surface temperature anomalies

    SciTech Connect

    Montroy, D.L.

    1997-04-01

    In past research the Southern Oscillation index has often been used as an indicator of the tropical Pacific climate, notably for El Nino and La Nina event occurrences. This study identifies calendar monthly teleconnection signals in central and eastern North American precipitation associated with an alternative tropical Pacific indicator, sea surface temperature anomaly (SSTA) patterns. Using an approximate 1{degrees} resolution set of monthly precipitation totals for 1950-92, the work identifies monthly teleconnection relationships and their intraseasonal evolution. This builds upon previous studies that were limited to seasonal timescales. Here, a unique two-way statistical analysis is used to delineate linear SSTA-precipitation teleconnection patterns.

  20. A study of temperature-related non-linearity at the metal-silicon interface

    NASA Astrophysics Data System (ADS)

    Gammon, P. M.; Donchev, E.; Pérez-Tomás, A.; Shah, V. A.; Pang, J. S.; Petrov, P. K.; Jennings, M. R.; Fisher, C. A.; Mawby, P. A.; Leadley, D. R.; McN. Alford, N.

    2012-12-01

    In this paper, we investigate the temperature dependencies of metal-semiconductor interfaces in an effort to better reproduce the current-voltage-temperature (IVT) characteristics of any Schottky diode, regardless of homogeneity. Four silicon Schottky diodes were fabricated for this work, each displaying different degrees of inhomogeneity; a relatively homogeneous NiV/Si diode, a Ti/Si and Cr/Si diode with double bumps at only the lowest temperatures, and a Nb/Si diode displaying extensive non-linearity. The 77-300 K IVT responses are modelled using a semi-automated implementation of Tung's electron transport model, and each of the diodes are well reproduced. However, in achieving this, it is revealed that each of the three key fitting parameters within the model display a significant temperature dependency. In analysing these dependencies, we reveal how a rise in thermal energy "activates" exponentially more interfacial patches, the activation rate being dependent on the carrier concentration at the patch saddle point (the patch's maximum barrier height), which in turn is linked to the relative homogeneity of each diode. Finally, in a review of Tung's model, problems in the divergence of the current paths at low temperature are explained to be inherent due to the simplification of an interface that will contain competing defects and inhomogeneities.

  1. Relating trends in land surface-air temperature difference to soil moisture and evapotranspiration

    NASA Astrophysics Data System (ADS)

    Veal, Karen; Taylor, Chris; Gallego-Elvira, Belen; Ghent, Darren; Harris, Phil; Remedios, John

    2016-04-01

    Soil water is central to both physical and biogeochemical processes within the Earth System. Drying of soils leads to evapotranspiration (ET) becoming limited or "water-stressed" and is accompanied by rises in land surface temperature (LST), land surface-air temperature difference (delta T), and sensible heat flux. Climate models predict sizable changes to the global water cycle but there is variation between models in the time scale of ET decay during dry spells. The e-stress project is developing novel satellite-derived diagnostics to assess the ability of Earth System Models (ESMs) to capture behaviour that is due to soil moisture controls on ET. Satellite records of LST now extend 15 years or more. MODIS Terra LST is available from 2000 to the present and the Along-Track Scanning Radiometer (ATSR) LST record runs from 1995 to 2012. This paper presents results from an investigation into the variability and trends in delta T during the MODIS Terra mission. We use MODIS Terra and MODIS Aqua LST and ESA GlobTemperature ATSR LST with 2m air temperatures from reanalyses to calculate trends in delta T and "water-stressed" area. We investigate the variability of delta T in relation to soil moisture (ESA CCI Passive Daily Soil Moisture), vegetation (MODIS Monthly Normalized Difference Vegetation Index) and precipitation (TRMM Multi-satellite Monthly Precipitation) and compare the temporal and spatial variability of delta T with model evaporation data (GLEAM). Delta T anomalies show significant negative correlations with soil moisture, in different seasons, in several regions across the planet. Global mean delta T anomaly is small (magnitude mostly less than 0.2 K) between July 2002 and July 2008 and decreases to a minimum in early 2010. The reduction in delta T anomaly coincides with an increase in soil moisture anomaly and NDVI anomaly suggesting an increase in evapotranspiration and latent heat flux with reduced sensible heat flux. In conclusion there have been

  2. Do CMIP5 Climate Models Reproduce Observed Historical Trends in Temperature and Precipitation over the Continental United States?

    NASA Astrophysics Data System (ADS)

    Lee, J.; Loikith, P. C.; Waliser, D. E.; Kunkel, K.

    2015-12-01

    Monitoring trends in key climate variables, such as surface temperature and precipitation, is an integral part of the ongoing efforts of the United States National Climate Assessment (NCA). Positive trends in both temperature and precipitation have been observed over the 20th century over much of the Continental United States (CONUS), however projections of future trends are reliant on climate model simulations. In order to have confidence in future projections of temperature and precipitation, it is crucial to evaluate the ability of current state-of-the-art climate models to reproduce historical observed trends. Towards this goal, trends in surface temperature and precipitation obtained from the NOAA nClimDiv 5 km gridded station observation-based product are compared to the suite of CMIP5 historical simulations over the CONUS region. The Regional Climate Model Evaluation System (RCMES), an analysis tool which supports the NCA by providing access to data and tools for regional climate model validation, is used to provide the comparisons between the models and observation. NASA TRMM precipitation data and MERRA surface temperature data are included in part of the analysis to observe how well satellite data and reanalysis compares to nClimDiv station observation data.

  3. Infrared line cameras based on linear arrays for industrial temperature measurement

    NASA Astrophysics Data System (ADS)

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

    2002-03-01

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

  4. Global patterns of the trends in satellite-derived crop yield proxy, temperature and soil moisture

    NASA Astrophysics Data System (ADS)

    Sakai, T.; Iizumi, T.; Sakurai, G.; Okada, M.; Nishimori, M.

    2014-12-01

    Crop productivity (yield) is sensitive to climate variability and change. To inform stakeholders, including food agencies in food-importing countries, about future variations in food supply associated with climate variability and change, understanding major climatic drivers of the spatiotemporal variations in crop yield over global cropland during the last few decades is crucial. Although remote sensing has difficulty distinguishing individual crops and misses entire cropping cycles in areas where extensive cloud cover during the monsoon limits satellite observations, it is still useful in deriving a proxy of crop yield over large spatial domain and estimating the impacts on crop yield proxy due to climate, including land-surface temperature and surface-layer soil moisture. This study presents an attempt to globally depict the impact of climate change on crop yield proxy by applying a time series analysis to MODIS and AMSR-E satellite images. The crop yield proxy used was the annual maximum or integrated MODIS-derived NDVI during the growing period predefined on the basis of the global crop calendar. The trends in the crop yield proxy in the interval 2001-2013 appeared positive in higher latitudes and negative in lower latitudes. In higher latitudes (and thus colder regions), the increased land-surface temperature led to an increase in crop yield in part due to the enhanced photosynthesis rate. In contrast, the crop yield proxy showed negative correlation with land-surface temperature in lower latitudes. The increased temperature might decrease crop yield by increasing evapotranspiration rate, plant respiration and/or heat stress. The crop yield proxy was also correlated with the AMSR-E-derived soil moisture, although the geographical distribution of soil moisture was highly heterogeneous.

  5. 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)

    Wilson, Robert M.

    2013-01-01

    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.

  6. Experimental Realization of Efficient, Room Temperature Single-Photon Sources with Definite Circular and Linear Polarizations

    NASA Astrophysics Data System (ADS)

    Boutsidis, Christos

    In this thesis I present experimental demonstrations of room-temperature, single-photon sources with definite linear and circular polarizations. Definite photon polarization increases the efficiency of quantum communication systems. In contrast with cryogenic-temperature single-photon sources based on epitaxial quantum dots requiring expensive MBE and nanofabrication, my method utilizes a mature liquid crystal technology, which I made consistent with single-emitter fluorescence microscopy. The structures I have prepared are planar-aligned cholesteric liquid crystals forming 1-D photonic bandgaps for circularly-polarized light, which were used to achieve definite circularly-polarized fluorescence of single emitters doped in this environment. I also used planar-aligned nematic liquid crystals to align single molecules with linear dipole moments and achieved definite linearly-polarized fluorescence. I used single nanocrystal quantum dots, single nanodiamond color-centers, rare-earth-doped nanocrystals, and single terrylene and DiIC18(3) dye molecules as emitters. For nanocrystal quantum dots I observed circular polarization dissymmetry factors as large as ge = --1.6. In addition, I observed circularly-polarized resonances in the fluorescence of emitters within a cholesteric microcavity, with cavity quality factors of up to Q ˜ 250. I also showed that the fluorescence of DiIC18(3) dye molecules in planar-aligned nematic cells exhibits definite linear polarization, with a degree of polarization of rho = --0.58 +/- 0.03. Distributed Bragg reflectors form another type of microcavity that can be used to realize a single-photon source. I characterized the fluorescence from nanocrystal quantum dots doped in the defect layers of such microcavites, both organic and inorganic. Finally, to demonstrate the single-photon properties of single-emitter-doped cholesteric and nematic liquid crystal structures and distributed Bragg reflector microcavities, I present observations of

  7. SILC: a new Planck internal linear combination CMB temperature map using directional wavelets

    NASA Astrophysics Data System (ADS)

    Rogers, Keir K.; Peiris, Hiranya V.; Leistedt, Boris; McEwen, Jason D.; Pontzen, Andrew

    2016-08-01

    We present new clean maps of the cosmic microwave background (CMB) temperature anisotropies (as measured by Planck) constructed with a novel internal linear combination (ILC) algorithm using directional, scale-discretized wavelets - scale-discretized, directional wavelet ILC or Scale-discretised, directional wavelet Internal Linear Combination (SILC). Directional wavelets, when convolved with signals on the sphere, can separate the anisotropic filamentary structures which are characteristic of both the CMB and foregrounds. Extending previous component separation methods, which use the frequency, spatial and harmonic signatures of foregrounds to separate them from the cosmological background signal, SILC can additionally use morphological information in the foregrounds and CMB to better localize the cleaning algorithm. We test the method on Planck data and simulations, demonstrating consistency with existing component separation algorithms, and discuss how to optimize the use of morphological information by varying the number of directional wavelets as a function of spatial scale. We find that combining the use of directional and axisymmetric wavelets depending on scale could yield higher quality CMB temperature maps. Our results set the stage for the application of SILC to polarization anisotropies through an extension to spin wavelets.

  8. Haematite natural crystals: non-linear initial susceptibility at low temperature

    NASA Astrophysics Data System (ADS)

    Guerrero-Suarez, S.; Martín-Hernández, F.

    2016-06-01

    Several works have reported that haematite has non-linear initial susceptibility at room temperature, like pyrrhotite or titanomagnetite, but there is no explanation for the observed behaviours yet. This study sets out to determine which physical property (grain size, foreign cations content and domain walls displacements) controls the initial susceptibility. The performed measurements include microprobe analysis to determine magnetic phases different to haematite; initial susceptibility (300 K); hysteresis loops, SIRM and backfield curves at 77 and 300 K to calculate magnetic parameters and minor loops at 77 K, to analyse initial susceptibility and magnetization behaviours below Morin transition. The magnetic moment study at low temperature is completed with measurements of zero field cooled-field cooled and AC susceptibility in a range from 5 to 300 K. The minor loops show that the non-linearity of initial susceptibility is closely related to Barkhausen jumps. Because of initial magnetic susceptibility is controlled by domain structure it is difficult to establish a mathematical model to separate magnetic subfabrics in haematite-bearing rocks.

  9. Low-temperature dynamics of weakly localized Frenkel excitons in disordered linear chains.

    PubMed

    Bednarz, M; Malyshev, V A; Knoester, J

    2004-02-22

    We calculate the temperature dependence of the fluorescence Stokes shift and the fluorescence decay time in linear Frenkel exciton systems resulting from the thermal redistribution of exciton population over the band states. The following factors, relevant to common experimental conditions, are accounted for in our kinetic model: (weak) localization of the exciton states by static disorder, coupling of the localized excitons to vibrations in the host medium, a possible nonequilibrium of the subsystem of localized Frenkel excitons on the time scale of the emission process, and different excitation conditions (resonant or nonresonant). A Pauli master equation, with microscopically calculated transition rates, is used to describe the redistribution of the exciton population over the manifold of localized exciton states. We find a counterintuitive nonmonotonic temperature dependence of the Stokes shift. In addition, we show that depending on experimental conditions, the observed fluorescence decay time may be determined by vibration-induced intraband relaxation, rather than radiative relaxation to the ground state. The model considered has relevance to a wide variety of materials, such as linear molecular aggregates, conjugated polymers, and polysilanes. PMID:15268548

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

  12. Local and linear chemical reactivity response functions at finite temperature in density functional theory.

    PubMed

    Franco-Pérez, Marco; Ayers, Paul W; Gázquez, José L; Vela, Alberto

    2015-12-28

    We explore the local and nonlocal response functions of the grand canonical potential density functional at nonzero temperature. In analogy to the zero-temperature treatment, local (e.g., the average electron density and the local softness) and nonlocal (e.g., the softness kernel) intrinsic response functions are defined as partial derivatives of the grand canonical potential with respect to its thermodynamic variables (i.e., the chemical potential of the electron reservoir and the external potential generated by the atomic nuclei). To define the local and nonlocal response functions of the electron density (e.g., the Fukui function, the linear density response function, and the dual descriptor), we differentiate with respect to the average electron number and the external potential. The well-known mathematical relationships between the intrinsic response functions and the electron-density responses are generalized to nonzero temperature, and we prove that in the zero-temperature limit, our results recover well-known identities from the density functional theory of chemical reactivity. Specific working equations and numerical results are provided for the 3-state ensemble model. PMID:26723661

  13. Local and linear chemical reactivity response functions at finite temperature in density functional theory

    SciTech Connect

    Franco-Pérez, Marco E-mail: ayers@mcmaster.ca E-mail: avela@cinvestav.mx; Ayers, Paul W. E-mail: ayers@mcmaster.ca E-mail: avela@cinvestav.mx; Gázquez, José L. E-mail: ayers@mcmaster.ca E-mail: avela@cinvestav.mx; Vela, Alberto E-mail: ayers@mcmaster.ca E-mail: avela@cinvestav.mx

    2015-12-28

    We explore the local and nonlocal response functions of the grand canonical potential density functional at nonzero temperature. In analogy to the zero-temperature treatment, local (e.g., the average electron density and the local softness) and nonlocal (e.g., the softness kernel) intrinsic response functions are defined as partial derivatives of the grand canonical potential with respect to its thermodynamic variables (i.e., the chemical potential of the electron reservoir and the external potential generated by the atomic nuclei). To define the local and nonlocal response functions of the electron density (e.g., the Fukui function, the linear density response function, and the dual descriptor), we differentiate with respect to the average electron number and the external potential. The well-known mathematical relationships between the intrinsic response functions and the electron-density responses are generalized to nonzero temperature, and we prove that in the zero-temperature limit, our results recover well-known identities from the density functional theory of chemical reactivity. Specific working equations and numerical results are provided for the 3-state ensemble model.

  14. Temperature trends in the tropical upper troposphere and lower stratosphere: Connections with sea surface temperatures and implications for water vapor and ozone

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

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

  16. Temperature condensation trend in the debris-disk binary system ζ2 Reticuli

    NASA Astrophysics Data System (ADS)

    Saffe, C.; Flores, M.; Jaque Arancibia, M.; Buccino, A.; Jofré, E.

    2016-04-01

    Context. Detailed abundance studies have reported different trends between samples of stars with and without planets, possibly related to the planet formation process. Whether these differences are still present between samples of stars with and without debris disk is still unclear. Aims: We explore condensation temperature Tc trends in the unique binary system ζ1 Ret -ζ2 Ret to determine whether there is a depletion of refractories that could be related to the planet formation process. The star ζ2 Ret hosts a debris disk which was detected by an IR excess and confirmed by direct imaging and numerical simulations, while ζ1 Ret does not present IR excess or planets. These characteristics convert ζ2 Ret in a remarkable system where their binary nature together with the strong similarity of both components allow us, for the first time, to achieve the highest possible abundance precision in this system. Methods: We carried out a high-precision abundance determination in both components of the binary system via a line-by-line, strictly differential approach. First we used the Sun as a reference and then we used ζ2 Ret. The stellar parameters Teff, log g, [Fe/H], and vturb were determined by imposing differential ionization and excitation equilibrium of Fe I and Fe II lines, with an updated version of the program FUNDPAR, together with plane-parallel local thermodynamic equilibrium ATLAS9 model atmospheres and the MOOG code. We then derived detailed abundances of 24 different species with equivalent widths and spectral synthesis with the MOOG program. The chemical patterns were compared with a recently calculated solar-twins Tc trend, and then mutually between both stars of the binary system. The rocky mass of depleted refractory material was estimated according to recent data. Results: The star ζ1 Ret is found to be slightly more metal rich than ζ2 Ret by ~0.02 dex. In the differential calculation of ζ1 Ret using ζ2 Ret as reference, the abundances of the

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  18. Trends analysis of precipitation and temperature in the Alto Genil basin (Southeast Spain) from 1970 to 2010

    NASA Astrophysics Data System (ADS)

    Fernández-Chacón, Francisca; Pulido-Velázquez, David; Jiménez-Sánchez, Jorge; Jimeno-Sáez, Patricia; Juan Collados-Lara, Antonio; Luque-Espinar, Juan Antonio

    2016-04-01

    The last studies of climate change predict a trend to more arid conditions in most of Spain. These studies show a significant increment in seasonal and annual air temperature, a reduction in mean precipitation and a raising number of extreme events of both variables. The historic data analysis is essential for identifying cycles, recent weather trends and to calibrate predictive models. In this work we analyses the recent historical climate in Alto Genil Basin. The system is located at SE Iberian Peninsula and includes an important part of the Sierra Nevada catchment. A high-resolution Spain02 dataset (~11 km) have been employed in this study. In accordance with the available data we have analyzed the period from 1970 to 2010 for daily precipitation and from 1970 to 2007 for daily temperature. In order to detect cycles and climate trends we have analyzed the temporal, seasonal and spatial distribution of the precipitation and temperature variables. We have calculated and analyzed the accumulated deviations from the mean daily precipitation. This analysis has been also performed with monthly and annual series. A non-parametric Mann Kendall method has been applied to study trends. In the period 1971-2007, the temperature has increased. The strongest trends appear since 1994. Between of 1971-1993 the average temperature observed was 13.6 °C, however from 1994 to 2007 the average temperature observed was 14.84 °C. Seasonally, during the study period, the spring has been the season with biggest increment in temperature. These temperature increments are more significant during March, April, May, June, July and October. In the period 1971-2010 the Mann Kendall test does not show a clear trend for precipitation. It is mainly due to the series culminates in three exceptional hydrological years that mask the overall trend of the study period. For this reason, we have also performed a sensitivity analysis of the Mann Kendall analysis to the period of data considered. On the

  19. An Investigation of Summertime Inland Water Body Temperatures in California and Nevada (USA): Recent Trends and Future Projections

    NASA Astrophysics Data System (ADS)

    Healey, Nathan; Hook, Simon; Piccolroaz, Sebastiano; Toffolon, Marco; Radocinski, Robert

    2016-04-01

    Inland water body temperature has been identified as an ideal indicator of potential climate change. Understanding inland water body temperature trends is important for forecasting impacts to limnological, biological, and hydrological resources. Many inland water bodies are situated in remote locations with incomplete data records of in-situ monitoring or lack in-situ observations altogether. Thus, the utilization of satellite data is essential for understanding the behavior of global inland water body temperatures. Part of this research provides an analysis of summertime (July-September) temperature trends in the largest California/Nevada (USA) inland water bodies between 1991 and 2015. We examine satellite temperature retrievals from ATSR (ATSR-1, ATSR-2, AATSR), MODIS (Terra and Aqua), and VIIRS sensors. Our findings indicate that inland water body temperatures in the western United States were rapidly warming between 1991 and 2009, but since then trends have been decreasing. This research also includes implementation of a model called air2water to predict future inland water body surface temperature through the sole input of air temperature. Using projections from CMIP5-CCSM4 output, our model indicates that Lake Tahoe (USA) is expected to experience an increase of roughly 3 °C by 2100.

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

    SciTech Connect

    Easter, R.C.; Peters, L.K.

    1993-01-01

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

  1. Monitoring of vulcanization process using measurement of electrical properties during linear increasing temperature

    NASA Astrophysics Data System (ADS)

    Seliga, E.; Bošák, O.; Koštial, P.; Dvořák, Z.; Kubliha, M.; Minárik, S.; Labaš, V.

    2015-04-01

    The article presents the possibilities of diagnostics of irreversible chemical reaction - vulcanization in case of laboratory prepared rubber mixture based on styrene - butadiene (SBR) using measurements of selected physical parameters. Our work is focused on the measurement of current rheologic parameters (torque at defined shear deformation) and selected electrical parameters (DC conductivity) during linear increasing temperature. The individual steps of vulcanization are well identified by means of measurements of rheologic parameters, while significantly affecting the value of the electrical conductivity. The value of the electrical conductivity increases with the increasing of rate of the crossbridging reactions during vulcanization. The rate of the heating affects both types of measurements. When the rate of the heating is increasing the temperature of the beginning of networking step of reactions and also the rate of vulcanization grow. The sensitivity of the both types of measurements allows a good mathematical description of the temperature dependence of the torque and the electric conductivity during the vulcanization of rubber mixtures based on SBR.

  2. Multi-sliding time windows based changing trend of mean temperature and its association with the global-warming hiatus

    NASA Astrophysics Data System (ADS)

    Shi, Yan; Zhai, Panmao; Jiang, Zhihong

    2016-04-01

    Based on three global annual mean surface temperature time series and three Chinese annual mean surface air temperature time series, climate change trends on multiple timescales are analyzed by using the trend estimation method of multi-sliding time windows. The results are used to discuss the so-called global-warming hiatus during 1998-2012. It is demonstrated that different beginning and end times have an obvious effect on the results of the trend estimation, and the implications are particularly large when using a short window. The global-warming hiatus during 1998-2012 is the result of viewing temperature series on short timescales; and the events similar to it, or the events with even cold tendencies, have actually occurred many times in history. Therefore, the global-warming hiatus is likely to be a periodical feature of the long-term temperature change. It mainly reflects the decadal variability of temperature, and such a phenomenon in the short term does not alter the overall warming trend in the long term.

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

    NASA Astrophysics Data System (ADS)

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

    2003-04-01

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

  4. Trends and variability of daily temperature extremes during 1960-2012 in the Yangtze River Basin, China

    NASA Astrophysics Data System (ADS)

    Guan, Yinghui; Zhang, Xunchang; Zheng, Fenli; Wang, Bin

    2015-01-01

    The variability of surface air temperature extremes has been the focus of attention during the past several decades, and may exert a great influence on the global hydrologic cycle and energy balance through thermal forcing. Based on daily minimum (TN) and maximum temperature (TX) observed by the China Meteorological Administration at 143 meteorological stations in the Yangtze River Basin (YRB), a suite of temperature indices recommended by the Expert Team on Climate Change Detection and Indices, with a primary focus on extreme events, were computed and analyzed for the period of 1960-2012 for this area. The results show widespread significant changes in all temperature indices associated with warming in the YRB during 1960-2012. On the whole, cold-related indices, i.e., cold nights, cold days, frost days, icing days and cold spell duration index significantly decreased by - 3.45, - 1.03, - 3.04, - 0.42 and - 1.6 days/decade, respectively. In contrast, warm-related indices such as warm nights, warm days, summer days, tropical nights and warm spell duration index significantly increased by 2.95, 1.71, 2.16, 1.05 and 0.73 days/decade. Minimum TN, maximum TN, minimum TX and maximum TX increased significantly by 0.42, 0.18, 0.19 and 0.14 °C/decade. Because of a faster increase in minimum temperature than maximum temperature, the diurnal temperature range (DTR) exhibited a significant decreasing trend of - 0.09 °C/decade for the whole YRB during 1960-2012. However, the decreasing trends all occurred in 1960-1985, while increasing trends though insignificant were found in all sub-regions and the whole YRB during 1986-2012. Geographically, stations in the eastern Tibet Plateau and northeastern YRB showed stronger trends in almost all temperature indices. Time series analysis indicated that the YRB was dominated by a general cooling trend before the mid-1980s, but a warming trend afterwards. In general, the overall warming in the YRB was mainly due to the warming in 1986

  5. Neutral atmosphere temperature trends and variability at 90 km, 70 °N, 19 °E, 2003-2014

    NASA Astrophysics Data System (ADS)

    Eriksen Holmen, Silje; Hall, Chris M.; Tsutsumi, Masaki

    2016-06-01

    Neutral temperatures at 90 km height above Tromsø, Norway, have been determined using ambipolar diffusion coefficients calculated from meteor echo fading times using the Nippon/Norway Tromsø Meteor Radar (NTMR). Daily temperature averages have been calculated from November 2003 to October 2014 and calibrated against temperature measurements from the Microwave Limb Sounder (MLS) on board Aura. Large-scale periodic oscillations ranging from ˜ 9 days to a year were found in the data using Lomb-Scargle periodogram analysis, and these components were used to seasonally detrend the daily temperature values before assessing trends. Harmonic oscillations found are associated with the large-scale circulation in the middle atmosphere together with planetary and gravity wave activity. The overall temperature change from 2003 to 2014 is -2.2 K ± 1.0 K decade-1, while in summer (May-June-July) and winter (November-December-January) the change is -0.3 K ± 3.1 K decade-1 and -11.6 K ± 4.1 K decade-1, respectively. The temperature record is at this point too short for incorporating a response to solar variability in the trend. How well suited a meteor radar is for estimating neutral temperatures at 90 km using meteor trail echoes is discussed, and physical explanations behind a cooling trend are proposed.

  6. Relating trends in land surface skin-air temperature difference to soil moisture and evapotranspiration.

    NASA Astrophysics Data System (ADS)

    Ghent, D.; Veal, K. L.; Taylor, C.; Gallego-Elvira, B.

    2015-12-01

    Soil water is central to both physical and biogeochemical processes within the Earth System. Drying of soils leads to evapotranspiration (ET) becoming limited (water-stressed) and is accompanied by rises in land surface temperature (LST), land surface-air temperature difference (delta T), and sensible heat flux. Climate models predict sizable changes to the global water cycle but there is variation between models in the time scale of ET decay during dry spells. The e-stress project is developing novel satellite-derived datasets to assess the ability of Earth System Models (ESMs) to capture behaviour that is due to soil moisture controls on ET. Satellite records of LST now extend 15 years or more (e.g. MODIS Terra LST - 2000 to present; Along-Track Scanning Radiometer (ATSR) LST record - 1995 to 2012). As part of the e-stress project these datasets have been used calculate time series of delta T. This paper reports the use of MODIS LST and ESA GlobTemperature ATSR LST with 2m air temperatures from a range of reanalyses to calculate trends in delta T and water-stressed area. We examine the variability of delta T in relation to satellite soil moisture, vegetation and precipitation and model evaporation data.Delta T anomalies show significant negative correlations with soil moisture, in different seasons, in several regions across the planet. Global mean delta T anomaly is small (magnitude mostly less than 0.2 K) between July 2002 and July 2008 and decreases to a minimum in early 2010. The reduction in delta T anomaly coincides with an increase in soil moisture anomaly and NDVI anomaly suggesting an increase in evapotranspiration and latent heat flux with reduced sensible heat flux.In conclusion there have been distinct signals in delta T during recent decades and these provide an independent assessment of hydrologically-forced changes in the land surface energy balance which can be used as a metric for the assessment of ESM and global surface flux products.

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

    NASA Astrophysics Data System (ADS)

    Gnanadesikan, A.; Pradal, M.

    2013-12-01

    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

  8. Preliminary density and temperature measurements in Lockheed Martin's magnetically encapsulated linear ring cusp confinement configuration

    NASA Astrophysics Data System (ADS)

    Sullivan, Regina; Heinrich, Jonathon; McCarren, Dustin; McGuire, Tom; Rhoads, John; Strandberg, Elizabeth

    2015-11-01

    Lockheed Martin's T4 experiment confines deuterium plasma with a magnetically encapsulated linear ring cusp configuration. Electron-Cyclotron Resonance Heating (ECRH) is used to generate and heat the plasma. An initial set of commissioning experiments at low-beta were performed on the device, across a range of ECRH powers and neutral gas pressures. Langmuir probe measurements were taken to determine the density and electron temperature of the plasma at these conditions, and to examine fluctuations in these parameters. The internal structure of the plasma was investigated using radial location sweeps of the probe. A 95 GHz microwave interferometer was used to independently measure line-averaged density, and results were compared to the probe data.

  9. Linear and nonlinear finite-element analysis of laminated composite structures at high temperatures

    SciTech Connect

    Wilt, T.E.

    1992-01-01

    A simple robust finite element which can effectively model the multilayer composite material is developed. This will include thermal gradient capabilities necessary for a complete thermomechanical analysis. In order to integrate the numerically stiff rate-dependent viscoplastic equations, efficient, stable numerical algorithms are developed. In addition, consistent viscoplastic/plastic tangent matrices are also formulated. The finite element is formulated based upon a generalized mixed variational principle with independently assumed displacements and layer-number independent strains. A unique scheme utilizing nodal temperatures is used to model a linear thermal gradient through the thickness of the composite. The numerical-integration algorithms are formulated in the context of a fully implicit backward Euler scheme. The consistent tangent matrices arise directly from the formulation. The multi-layer composite finite element demonstrates good performance in terms of static displacement and stress predictions, and dynamic response.

  10. Thermal inactivation kinetics of Bacillus stearothermophilus spores using a linear temperature program.

    PubMed

    Leontidis, S; Fernández, A; Rodrigo, C; Fernández, P S; Magraner, L; Martínez, A

    1999-08-01

    A systematic study of the inactivation kinetics of Bacillus stearothermophilus spores was carried out in nonisothermic heating conditions using a linear temperature increase program and analyzing the experimental data by means of a one-step nonlinear regression. The D and z values estimated are close to those obtained in isothermic conditions and estimated by using a two-step model, first D values are calculated, and then in the second step a z value is deduced (D(121 degrees C) = 3.08 and 4.38 min, respectively, and z = 7 and 7.9 degrees C, respectively). No convergence problems were observed when using the one-step nonlinear regression proposed. The results indicated that the methodology applied in this study can be used to obtain kinetic data for bacterial spores, which could mean a significant reduction in the amount of experimental work employed to generate these data. PMID:10456754

  11. Hematite natural crystals: non-linear initial susceptibility at low temperature

    NASA Astrophysics Data System (ADS)

    Guerrero Suarez, S.; Martín-Hernández, F.

    2016-04-01

    Several works have reported that hematite has non-linear initial susceptibility at room temperature, like pyrrhotite or titanomagnetite, but there is no explanation for the observed behaviours yet. This study sets out to determine which physical property (grain-size, foreign cations content, domain walls displacements) controls the initial susceptibility. The performed measurements include microprobe analysis to determine magnetic phases different to hematite; initial susceptibility (300 K); hysteresis loops, SIRM and backfield curves at 77 K and 300 K to calculate magnetic parameters and minor loops at 77 K, to analyze initial susceptiblity and magnetization behaviours below Morin transition. The magnetic moment study at low temperatura is completed with measurements of Zero Field Cooled- Field Cooled (ZFC-FC) and AC-susceptibility in a range from 5-300 K. The minor loops show that the non-linearity of initial susceptibility is closely related to Barkhausen jumps. Because of initial magnetic susceptibility is controlled by domain structure it is difficult to establish a mathematical model to separate magnetic subfabrics in hematite-bearing rocks.

  12. Linear response to leadership, effective temperature, and decision making in flocks.

    PubMed

    Pearce, Daniel J G; Giomi, Luca

    2016-08-01

    Large collections of autonomously moving agents, such as animals or micro-organisms, are able to flock coherently in space even in the absence of a central control mechanism. While the direction of the flock resulting from this critical behavior is random, this can be controlled by a small subset of informed individuals acting as leaders of the group. In this article we use the Vicsek model to investigate how flocks respond to leadership and make decisions. Using a combination of numerical simulations and continuous modeling we demonstrate that flocks display a linear response to leadership that can be cast in the framework of the fluctuation-dissipation theorem, identifying an effective temperature reflecting how promptly the flock reacts to the initiative of the leaders. The linear response to leadership also holds in the presence of two groups of informed individuals with competing interests, indicating that the flock's behavioral decision is determined by both the number of leaders and their degree of influence. PMID:27627365

  13. Effect of recent sea surface temperature trends on the Arctic stratospheric vortex

    NASA Astrophysics Data System (ADS)

    Garfinkel, C. I.; Hurwitz, M. M.; Oman, L. D.

    2015-06-01

    Comprehensive chemistry-climate model experiments and observational data are used to show that up to half of the satellite era early springtime cooling trend in the Arctic lower stratosphere was caused by changing sea surface temperatures (SSTs). An ensemble of experiments forced only by changing SSTs is compared to an ensemble of experiments in which both the observed SSTs and chemically and radiatively active trace species are changing. By comparing the two ensembles, it is shown that warming of Indian Ocean, North Pacific, and North Atlantic SSTs and cooling of the tropical Pacific have strongly contributed to recent polar stratospheric cooling in late winter and early spring. When concentrations of ozone-depleting substances and greenhouse gases are fixed, polar ozone concentrations show a small but robust decline due to changing SSTs. Ozone loss is larger in the presence of changing concentrations of ozone-depleting substances and greenhouse gases. The stratospheric changes can be understood by examining the tropospheric height and heat flux anomalies generated by the anomalous SSTs. Finally, recent SST changes have contributed to a decrease in the frequency of late winter stratospheric sudden warmings.

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

    NASA Astrophysics Data System (ADS)

    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

    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

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

    NASA Technical Reports Server (NTRS)

    Clancy, R. Todd; Rusch, David W.

    1989-01-01

    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.

  16. The effects of urbanization on temperature trends in different economic periods and geographical environments in northwestern China

    NASA Astrophysics Data System (ADS)

    Fang, Feng; Guo, Junqin; Sun, Landong; Wang, Jing; Wang, Xinping

    2014-04-01

    Using data collected from 22 urban and 65 rural meteorological stations in northwestern China between 1961 and 2009, this paper presents a study concerning the effects of urbanization on air temperature trends. To distinguish among the potential influences that stem from the economic development levels, population scales, and geographic environments of the cities in this region, the 49-year study period was divided into two periods: a period of less economic development, from 1961 to 1978, and a period of greater economic development, from 1979 to 2009. Each of the cities was classified as a megalopolis, large, or medium-small, depending on the population, and each was classified as a plateau, plain, or oasis city, depending on the surrounding geography. The differences in the air temperature trends between cities and the average of their rural counterparts were used to examine the warming effects of urbanization. The results of this study indicate that the magnitude of warming effects due to urbanization depends not only on a city's economic level, but also on the population scale and geographic environment of the city. The urbanization of most cities in northwestern China resulted in considerable negative warming effects during 1961-1978 but evidently positive effects during 1979-2009. The population scale of a city represents a significant factor: a city with a larger population has a stronger warming influence, regardless of whether the effect is negative or positive. Among the three geographic environments of the cities considered, plateaus and plains more significantly enhance warming effects than oases. The urban population trend has a very significant logarithm relationship with the urban temperature effect, but no clear relationships between urban temperature effects and city elevation were detected. The majority of the temperature trends, accounting for more than 60 % of the trends during 1961-2009, can be explained by natural factors, although

  17. Comparison of equatorial Pacific sea surface temperature variability and trends with Sr/Ca records from multiple corals

    NASA Astrophysics Data System (ADS)

    Alpert, Alice E.; Cohen, Anne L.; Oppo, Delia W.; DeCarlo, Thomas M.; Gove, Jamison M.; Young, Charles W.

    2016-02-01

    Coral Sr/Ca is widely used to reconstruct past ocean temperatures. However, some studies report different Sr/Ca-temperature relationships for conspecifics on the same reef, with profound implications for interpretation of reconstructed temperatures. We assess whether these differences are attributable to small-scale oceanographic variability or "vital effects" associated with coral calcification and quantify the effect of intercolony differences on temperature estimates and uncertainties. Sr/Ca records from four massive Porites colonies growing on the east and west sides of Jarvis Island, central equatorial Pacific, were compared with in situ logger temperatures spanning 2002-2012. In general, Sr/Ca captured the occurrence of interannual sea surface temperature events but their amplitude was not consistently recorded by any of the corals. No long-term trend was identified in the instrumental data, yet Sr/Ca of one coral implied a statistically significant cooling trend while that of its neighbor implied a warming trend. Slopes of Sr/Ca-temperature regressions from the four different colonies were within error, but offsets in mean Sr/Ca rendered the regressions statistically distinct. Assuming that these relationships represent the full range of Sr/Ca-temperature calibrations in Jarvis Porites, we assessed how well Sr/Ca of a nonliving coral with an unknown Sr/Ca-temperature relationship can constrain past temperatures. Our results indicate that standard error of prediction methods underestimate the actual error as we could not reliably reconstruct the amplitude or frequency of El Niño-Southern Oscillation events as large as ± 2°C. Our results underscore the importance of characterizing the full range of temperature-Sr/Ca relationships at each study site to estimate true error.

  18. 20th Century Trends In The Maximum And Minimum Temperatures In Colorado’s San Juan Mountains

    NASA Astrophysics Data System (ADS)

    Rangwala, I.; Miller, J. R.

    2009-12-01

    We examine the maximum (Tmax) and minimum (Tmin) temperature changes in San Juan Mountain (SJM) region of southwestern Colorado between 1895-2005. We analyze monthly averaged observations from 6 National Weather Service (NWS) stations between 1895-1949, and 25 NWS stations between 1950-2005. These changes are evaluated on annual, seasonal and monthly bases. Annually, our results suggest a long-term gradual warming trend in Tmin and no such discernable trend in Tmax. However, between 1990 and 2005, the region experiences a rapid warming trend with both Tmax and Tmin increasing by 1 degree C. Between 1950 and 1985, there is a regional cooling trend during which there are significant decreases in Tmax and almost no trend in Tmin. Similar to the annual trends, only Tmin shows a gradual warming trend during the 20th century during all seasons. Furthermore, during fall and summer, there is a lower correlation between Tmax and Tmin as compared to winter and spring. Between 1990-2005, Tmax increases more than Tmin during summer and spring, whereas Tmin shows greater increases during winter. We also examine Tmax and Tmin trends from 23 Snow Telemetry (SNOTEL) sites in the region between 1984-2005. We find strong correlation between NWS and SNOTEL observations, both annually and seasonally. Between 1990-2005, the largest warming at the SNOTEL sites occurs during summer while it is largest during winter at the NWS sites. Spatially, there are similar increases in Tmax and Tmin except in the central mountain region, where increases in Tmin started earlier and are greater. Physical mechanisms for these observed trends in Tmax and Tmin will be discussed.

  19. Scale-dependency of the global mean surface temperature trend and its implication for the recent hiatus of global warming

    PubMed Central

    Lin, Yong; Franzke, Christian L. E.

    2015-01-01

    Studies of the global mean surface temperature trend are typically conducted at a single (usually annual or decadal) time scale. The used scale does not necessarily correspond to the intrinsic scales of the natural temperature variability. This scale mismatch complicates the separation of externally forced temperature trends from natural temperature fluctuations. The hiatus of global warming since 1999 has been claimed to show that human activities play only a minor role in global warming. Most likely this claim is wrong due to the inadequate consideration of the scale-dependency in the global surface temperature (GST) evolution. Here we show that the variability and trend of the global mean surface temperature anomalies (GSTA) from January 1850 to December 2013, which incorporate both land and sea surface data, is scale-dependent and that the recent hiatus of global warming is mainly related to natural long-term oscillations. These results provide a possible explanation of the recent hiatus of global warming and suggest that the hiatus is only temporary. PMID:26259555

  20. Scale-dependency of the global mean surface temperature trend and its implication for the recent hiatus of global warming

    NASA Astrophysics Data System (ADS)

    Lin, Yong; Franzke, Christian L. E.

    2015-08-01

    Studies of the global mean surface temperature trend are typically conducted at a single (usually annual or decadal) time scale. The used scale does not necessarily correspond to the intrinsic scales of the natural temperature variability. This scale mismatch complicates the separation of externally forced temperature trends from natural temperature fluctuations. The hiatus of global warming since 1999 has been claimed to show that human activities play only a minor role in global warming. Most likely this claim is wrong due to the inadequate consideration of the scale-dependency in the global surface temperature (GST) evolution. Here we show that the variability and trend of the global mean surface temperature anomalies (GSTA) from January 1850 to December 2013, which incorporate both land and sea surface data, is scale-dependent and that the recent hiatus of global warming is mainly related to natural long-term oscillations. These results provide a possible explanation of the recent hiatus of global warming and suggest that the hiatus is only temporary.

  1. Decadal trend of precipitation and temperature patterns and impacts on snow-related variables in a semiarid region, Sierra Nevada, Spain.

    NASA Astrophysics Data System (ADS)

    José Pérez-Palazón, María; Pimentel, Rafael; Herrero, Javier; José Polo, María

    2016-04-01

    , with the exception of the average annual mean and maximum daily temperature. In the case of the snow-related variables, no significant trends are observed at this time scale; nonetheless, a global decreasing rate is predominant in most of the variables. The torrential events are more frequent in the last decades of the study period, with an apparently increasing associated dispersion. This study constitutes a first sound analysis of the long-term observed trends of the snow regime in this area under the context of increasing temperature and decreasing precipitation regimes. The results highlight the complexity of non-linearity in environmental processes in Mediterranean regions, and point out to a significant shift in the precipitation and temperature regime, and thus on the snow-affected hydrological variables in the study area.

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

  3. A high temperature hybrid photovoltaic-thermal receiver employing spectral beam splitting for linear solar concentrators

    NASA Astrophysics Data System (ADS)

    Mojiri, Ahmad; Stanley, Cameron; Rosengarten, Gary

    2015-09-01

    Hybrid photovoltaic/thermal (PV-T) solar collectors are capable of delivering heat and electricity concurrently. Implementing such receivers in linear concentrators for high temperature applications need special considerations such as thermal decoupling of the photovoltaic (pv) cells from the thermal receiver. Spectral beam splitting of concentrated light provides an option for achieving this purpose. In this paper we introduce a relatively simple hybrid receiver configuration that spectrally splits the light between a high temperature thermal fluid and silicon pv cells using volumetric light filtering by semi-conductor doped glass and propylene glycol. We analysed the optical performance of this device theoretically using ray tracing and experimentally through the construction and testing of a full scale prototype. The receiver was mounted on a commercial parabolic trough concentrator in an outdoor experiment. The prototype receiver delivered heat and electricity at total thermal efficiency of 44% and electrical efficiency of 3.9% measured relative to the total beam energy incident on the primary mirror.

  4. A SiC NMOS Linear Voltage Regulator for High-Temperature Applications

    SciTech Connect

    Valle-Mayorga, JA; Rahman, A; Mantooth, HA

    2014-05-01

    The first SiC integrated circuit linear voltage regulator is reported. The voltage regulator uses a 20-V supply and generates an output of 15 V, adjustable down to 10 V. It was designed for loads of up to 2 A over a temperature range of 25-225 degrees C. It was, however, successfully tested up to 300 degrees C. The voltage regulator demonstrated load regulations of 1.49% and 9% for a 2-A load at temperatures of 25 and 300 degrees C, respectively. However, the load regulation is less than 2% up to 300 degrees C for a 1-A load. The line regulation with a 2-A load at 25 and 300 degrees C was 17 and 296 mV/V, respectively. The regulator was fabricated in a Cree 4H-SiC 2-mu m experimental process and consists of 1000, 32/2-mu m NMOS depletion MOSFETs as the pass device, an integrated error amplifier with enhancement MOSFETs, and resistor loads, and uses external feedback and compensation networks to ensure operational integrity. It was designed to be integrated with high-voltage vertical power MOSFETs on the same SiC substrate. It also serves as a guide to future attempts for voltage regulation in any type of integrated SiC circuitry.

  5. A Novel Method making direct use of AIRS and IASI Calibrated Radiances for Measuring Trends in Surface Temperatures

    NASA Astrophysics Data System (ADS)

    Aumann, H. H.; Ruzmaikin, A.

    2014-12-01

    Making unbiased measurements of trends in the surface temperatures, particularly on a gobal scale, is challenging: While the non-frozen oceans temperature measurements are plentiful and accurate, land and polar areas are much less accurately or fairly sampled. Surface temperature deduced from infrared radiometers on polar orbiting satellites (e.g. the Atmospheric Infrared Sounder (AIRS) at 1:30PM, the Interferometer Atmosphere Sounding Interferometer (IASI) at 9:30 AM and the MODerate resolution Imaging Spectro-radiometer (MODIS) at 1:30PM), can produce what appear to be well sampled data, but dealing with clouds either by cloud filtering (MODIS, IASI) or cloud-clearing (AIRS) can create sampling bias. We use a novel method: Random Nadir Sampling (RNS) combined with Probability Density Function (PDF) analysis. We analyze the trend in the PDF of st1231, the water vapor absorption corrected brightness temperatures measured in the 1231 cm-1 atmospheric window channel. The advantage of this method is that trends can be directly traced to the known, less than 3 mK/yr trend for AIRS, in st1231. For this study we created PDFs from 22,000 daily RNS from the AIRS and IASI data. We characterized the PDFs by its daily 90%tile value, st1231p90, and analysed the statistical properties of the this time series between 2002 and 2014. The method was validated using the daily NOAA SST (RTGSST) from the non-frozen oceans: The mean, seasonal variability and anomaly trend of st1231p90 agree with the corrsponding values from the RTGSST and the anomaly correlation is larger than 0.9. Preliminary results (August 2014) confirm the global hiatus in the increase of the globally averaged surface temperatures between 2002 and 2014, with a change of less than 10 mK/yr. This uncertainty is dominated by the large interannual variability related to El Niño events. Further insite is gained by analyzing land/ocean, day/night, artic and antarctic trends. We observe a massive warming trend in the

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

    USGS Publications Warehouse

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

    2006-01-01

    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.

  7. Low temperature growth of diamond films on optical fibers using Linear Antenna CVD system

    NASA Astrophysics Data System (ADS)

    Ficek, M.; Drijkoningen, S.; Karczewski, J.; Bogdanowicz, R.; Haenen, K.

    2016-01-01

    It is not trivial to achieve a good quality diamond-coated fibre interface due to a large difference in the properties and composition of the diamond films (or use coating even) and the optical fibre material, i.e. fused silica. One of the biggest problems is the high temperature during the deposition which influences the optical fibre or optical fibre sensor structure (e.g. long-period gratings (LPG)). The greatest advantage of a linear antenna microwave plasma enhanced chemical vapor deposition system (LA MW CVD) is the fact that it allows to grow the diamond layers at low temperature (below 300°C) [1]. High quality nanocrystalline diamond (NCD) thin films with thicknesses ranging from 70 nm to 150 nm, were deposited on silicon, glass and optical fibre substrates [2]. Substrates pretreatment by dip-coating and spin coating process with a dispersion consisting of detonation nanodiamond (DND) in dimethyl sulfoxide (DMSO) with polyvinyl alcohol (PVA) has been applied. During the deposition process the continuous mode of operation of the LA MW CVD system was used, which produces a continuous wave at a maximum power of 1.9 kW (in each antenna). Diamond films on optical fibres were obtained at temperatures below 350°C, providing a clear improvement of results compared to our earlier work [3]. The samples were characterized by scanning electron microscopy (SEM) imaging to investigate the morphology of the nanocrystalline diamond films. The film growth rate, film thickness, and optical properties in the VIS-NIR range, i.e. refractive index and extinction coefficient will be discussed based on measurements on reference quartz plates by using spectroscopic ellipsometry (SE).

  8. The long-term trend in the diurnal temperature range over Asia and its natural and anthropogenic causes

    NASA Astrophysics Data System (ADS)

    Liu, Lin; Li, Zhanqing; Yang, Xin; Gong, Hainan; Li, Chao; Xiong, Anyuan

    2016-04-01

    Understanding the causes of long-term temperature trends is at the core of climate change studies. Any observed trend can result from natural variability or anthropogenic influences or both. In the present study, we evaluated the performance of 18 climate models from the Coupled Model Intercomparison Project Phase 5 on simulating the Asian diurnal temperature range (DTR) and explored the potential causes of the long-term trend in the DTR by examining the response of the DTR to natural forcing (volcanic aerosols and solar variability) and anthropogenic forcing (anthropogenic greenhouse gases (GHG) and aerosols) in the historical period of 1961-2005. For the climatology, the multimodel ensemble mean reproduced the geographical distribution and amplitude of the DTR over eastern China and India but underestimated the magnitudes of the DTR over the Tibetan Plateau and the high-latitude regions of the Asian continent. These negative biases in the DTR over frigid zones existed in most models. Seasonal biases in the DTR pattern from models were similar to the bias in the annual mean DTR pattern. Based on three selected state-of-the-art models, the observed decreasing trend in the DTR over Asia was reasonably reproduced in the all-forcing run. A comparison of separate forcing experiments revealed that anthropogenic forcing plays the dominant role in the declining trend in the DTR. Observations and model simulations showed that GHG forcing is mainly responsible for the negative trends in the DTR over Asia but that anthropogenic aerosol forcing was also behind the decreasing trend in the DTR over China and especially over eastern China.

  9. Spatial patterns of Antarctic surface temperature trends in the context of natural variability: Lessons from the CMIP5 Models

    NASA Astrophysics Data System (ADS)

    Smith, K. L.; Polvani, L. M.

    2015-12-01

    The recent annually averaged warming of the Antarctic Peninsula, and of West Antarctica, stands in stark contrast to very small and weakly negative trends over East Antarctica. This asymmetry arises primarily from a highly significant warming of West Antarctica in austral spring and a strong cooling of East Antarctic in austral autumn. Here we examine whether this East-West asymmetry is a response to anthropogenic climate forcings or a manifestation of natural climate variability. We compare the observed Antarctic surface air temperature (SAT) trends from five temperature reconstructions over two distinct time periods (1979-2005 and 1960-2005), and with those simulated by 40 coupled models participating in Phase 5 of the Coupled Model Intercomparison Project. We find that the observed East-West asymmetry differs substantially over the two time periods and, furthermore, is completely absent from the CMIP5 multi-model mean (from which all natural variability is eliminated by the averaging). We compare the CMIP5 SAT trends to those of 29 historical atmosphere-only simulations with prescribed sea surface temperatures (SSTs) and sea ice and find that these simulations are in better agreement with the observations. This suggests that natural multi-decadal variability associated with SSTs and sea ice and not external forcings is the primary driver of Antarctic SAT trends. We confirm this by showing that the observed trends lie within the distribution of multi-decadal trends from the CMIP5 pre-industrial integrations. These results, therefore, offer new evidence which points to natural climate variability as the more likely cause of the recent warming of West Antarctica and of the Peninsula.

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

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

    California summertime July to August (JJA) mean monthly air temperatures (1970-2005) were analyzed for two California air basins: South Coast (SoCAB) and the San Francisco Bay Area (SFBA), which extended into the Central Valley (CV). Daily Tmin and Tmax values were used to produce average monthly values and spatial distributions of and Tmax values trends for each air basin. Results showed concurrent cooling in coastal areas and warming at further inland areas. This pattern suggests that the regional-warming of inland areas resulted in increased coastal sea breeze activity. Further investigations by use of mesoscale model simulations with the Regional Atmospheric Modeling System (RAMS) meso-met model with a horizontal grid resolution of 4 km on an inner grid over SoCAB were undertaken to investigate the effects of long-term changes due to green house gas (GHG) warming and land-use land-cover changes on coastal flows. Comparison of simulated present (2000-4) and past climate (1970-4) conditions showed significant increases in sea breeze activity and thus coastal cooling, which supports the observational analysis results that coastal cooling is an indirect “reverse reaction” of GHG warming. The magnitude and location of the simulated and observed coastal-cooling region were in good agreement. Urbanization effects on coastal environment were twofold: increased urban mechanical surface roughness retards sea breeze flows, while urban heat islands (UHIs) enhance them. Significant beneficial societal impacts will result from this observed reverse-reaction to global-warming, especially during UHI-growth periods, include decreased maximum: agricultural production, O3 levels, per-capita energy requirements for cooling, and human thermal-stress levels. Similar “reverse-reaction” effects should be found in other mid-latitude western coastal-regions.

  11. Trends in extreme daily rainfall and temperature in Southeast Asia and the South Pacific: 1961-1998

    NASA Astrophysics Data System (ADS)

    Manton, M. J.; della-Marta, P. M.; Haylock, M. R.; Hennessy, K. J.; Nicholls, N.; Chambers, L. E.; Collins, D. A.; Daw, G.; Finet, A.; Gunawan, D.; Inape, K.; Isobe, H.; Kestin, T. S.; Lefale, P.; Leyu, C. H.; Lwin, T.; Maitrepierre, L.; Ouprasitwong, N.; Page, C. M.; Pahalad, J.; Plummer, N.; Salinger, M. J.; Suppiah, R.; Tran, V. L.; Trewin, B.; Tibig, I.; Yee, D.

    2001-03-01

    Trends in extreme daily temperature and rainfall have been analysed from 1961 to 1998 for Southeast Asia and the South Pacific. This 38-year period was chosen to optimize data availability across the region. Using high-quality data from 91 stations in 15 countries, significant increases were detected in the annual number of hot days and warm nights, with significant decreases in the annual number of cool days and cold nights. These trends in extreme temperatures showed considerable consistency across the region. Extreme rainfall trends were generally less spatially coherent than were those for extreme temperature. The number of rain days (with at least 2 mm of rain) has decreased significantly throughout Southeast Asia and the western and central South Pacific, but increased in the north of French Polynesia, in Fiji, and at some stations in Australia. The proportion of annual rainfall from extreme events has increased at a majority of stations. The frequency of extreme rainfall events has declined at most stations (but not significantly), although significant increases were detected in French Polynesia. Trends in the average intensity of the wettest rainfall events each year were generally weak and not significant.

  12. Looking back and looking forwards: Historical and future trends in sea surface temperature (SST) in the Indo-Pacific region from 1982 to 2100

    NASA Astrophysics Data System (ADS)

    Khalil, Idham; Atkinson, Peter M.; Challenor, Peter

    2016-03-01

    The ocean warming trend is a well-known global phenomenon. As early as 2001, and then reiterated in 2007, the Intergovernmental Panel on Climate Change (IPCC) reported that the global average sea surface temperature (SST) will increase by about 0.2 °C per decade. To date, however, only a limited number of studies have been published reporting the spatio-temporal trends in SST in the Indo-Pacific region, one the richest marine ecosystems on Earth. In this research, the monthly 1° spatial resolution NOAA Optimum Interpolation (OI) sea surface temperature (SST) V2 dataset (OISSTv2) derived from measurements made by the Advanced Very High Resolution Radiometer (AVHRR) and in situ measurements, were used to examine the spatio-temporal trends in SST in the region. The multi-model mean SST from the Representative Concentration Pathways (RCP2.6) mitigation scenario of the Coupled Model Intercomparison Project Phase 5 (CMIP5) was also used to forecast future SST from 2020 to 2100, decadally. Three variables from the OISSTv2, namely maximum (MaxSST), mean (MeanSST) and minimum (MinSST) monthly mean SST, were regressed against time measured in months from 1982 to 2010 using linear regression. Results revealed warming trends detected for all three SST variables. In the Coral Triangle a warming trend with a rate of 0.013 °C year-1, 0.017 °C year-1, and 0.019 °C year-1 was detected over 29 years for MaxSST, MeanSST and MinSST, respectively. In the SCS, the warming rate was 0.011 °C year-1, (MaxSST), 0.012 °C year-1 (MeanSST) and 0.015 °C year-1 (MinSST) over 29 years. The CMIP5 RCP2.6 forecast suggested a future warming rate to 2100 of 0.004 °C year-1 for both areas, and for all three SST variables. The warming trends reported in this study provide useful insights for improved marine-related management.

  13. Effects and Mitigation of Clear Sky Sampling on Recorded Trends in Land Surface Temperature

    NASA Astrophysics Data System (ADS)

    Holmes, T. R.; Hain, C.; de Jeu, R.; Anderson, M. C.; Crow, W. T.

    2015-12-01

    Land surface temperature (LST) is a key input for physically-based retrieval algorithms of hydrological states and fluxes. Yet, it remains a poorly constrained parameter for global scale studies. The main two observational methods to remotely measure T are based on thermal infrared (TIR) observations and passive microwave observations (MW). TIR is the most commonly used approach and the method of choice to provide standard LST products for various satellite missions. MW-based LST retrievals on the other hand are not as widely adopted for land applications; currently their principle use is in soil moisture retrieval algorithms. MW and TIR technologies present two highly complementary and independent means of measuring LST. MW observations have a high tolerance to clouds but a low spatial resolution, and TIR has a high spatial resolution with temporal sampling restricted to clear skies. This paper builds on recent progress in characterizing the main structural differences between TIR LST and MW Ka-band observations, the MW frequency that is most suitable for LST sensing. By accounting for differences in diurnal timing (phase lag with solar noon), amplitude, and emissivity we construct a MW-based LST dataset that matches the diurnal characteristics of the TIR-based LSA SAF LST record. This new global dataset of MW-based LST currently spans the period of 2003-2013. In this paper we will present results of a validation of MW LST with in situ data with special emphasis on the effect of cloudiness on the performance. The ability to remotely sense the temperature of cloud covered land is what sets this MW-LST datasets apart from existing (much higher resolution) TIR-based products. As an example of this we will therefore explore how MW LST can mitigate the effect of clear-sky sampling in the context of trend and anomaly detection. We do this by contrasting monthly means of TIR-LST with its clear-sky and all-sky equivalent from an MW-LST and an NWP model.

  14. Prediction of tropical Atlantic sea surface temperatures using linear inverse modeling

    SciTech Connect

    Penland, C.; Matrosova, L.

    1998-03-01

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

  15. Long-term changes/trends in surface temperature and precipitation during the satellite era (1979-2012)

    NASA Astrophysics Data System (ADS)

    Gu, Guojun; Adler, Robert F.; Huffman, George J.

    2016-02-01

    During the post-1979 period in which the satellite-based precipitation measurements with global coverage are available, global mean surface temperature rapidly increased up to late 1990s, followed by a period of temperature hiatus after about 1998/1999. Comparing observed surface temperature trends against the simulated ones by the CMIP5 historical experiments especially in the zonal mean context suggests that although the anthropogenic greenhouse-gases (GHG) forcing has played a major role, in addition to the anthropogenic aerosols and various natural forcings, the effects from decadal-to-interdecadal-scale internal modes specifically the Pacific Decadal Oscillation (PDO) are also very strong. Evident temperature changes associated with the PDO's phase shift are seen in the Pacific basin, with decadal-scale cooling in the tropical central-eastern Pacific and most of the east basin and concurrent warming in the subtropics of both hemispheres, even though the PDO's net effect on global mean temperature is relatively weak. The Atlantic Multidecadal Oscillation (AMO) also changed its phase in the mid-1990s, and hence its possible impact is estimated and assessed as well. However, comparisons with CMIP5 simulations suggest that the AMO may have not contributed as significantly as the PDO in terms of the changes/trends in global surface temperature, even though the data analysis technique used here suggests otherwise. Long-term precipitation changes or trends during the post-1979 period are further shown to have been modulated by the two major factors: anthropogenic GHG and PDO, in addition to the relatively weak effects from aerosols and natural forcings. The spatial patterns of observed precipitation trends in the Pacific, including reductions in the tropical central-eastern Pacific and increases in the tropical western Pacific and along the South Pacific Convergence Zone, manifest the PDO's contributions. Removing the PDO effect from the total precipitation trends

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

    PubMed

    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

    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

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

    USGS Publications Warehouse

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

    2011-01-01

    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.

  18. Surface temperature cooling trends and negative radiative forcing due to land use change toward greenhouse farming in southeastern Spain

    NASA Astrophysics Data System (ADS)

    Campra, Pablo; Garcia, Monica; Canton, Yolanda; Palacios-Orueta, Alicia

    2008-09-01

    Greenhouse horticulture has experienced in recent decades a dramatic spatial expansion in the semiarid province of Almeria, in southeastern (SE) Spain, reaching a continuous area of 26,000 ha in 2007, the widest greenhouse area in the world. A significant surface air temperature trend of -0.3°C decade-1 in this area during the period 1983-2006 is first time reported here. This local cooling trend shows no correlation with Spanish regional and global warming trends. Radiative forcing (RF) is widely used to assess and compare the climate change mechanisms. Surface shortwave RF (SWRF) caused through clearing of pasture land for greenhouse farming development in this area is estimated here. We present the first empirical evidences to support the working hypothesis of the development of a localized forcing created by surface albedo change to explain the differences in temperature trends among stations either inside or far from this agricultural land. SWRF was estimated from satellite-retrieved surface albedo data and calculated shortwave outgoing fluxes associated with either uses of land under typical incoming solar radiation. Outgoing fluxes were calculated from Moderate Resolution Imaging Spectroradiometer (MODIS) surface reflectance data. A difference in mean annual surface albedo of +0.09 was measured comparing greenhouses surface to a typical pasture land. Strong negative forcing associated with land use change was estimated all year round, ranging from -5.0 W m-2 to -34.8 W m-2, with a mean annual value of -19.8 W m-2. According to our data of SWRF and local temperatures trends, recent development of greenhouse horticulture in this area may have masked local warming signals associated to greenhouse gases increase.

  19. Evolution of rainfall and temperature trend and variability in Burkina Faso: Analysis of meteorological data and farmers' perception

    NASA Astrophysics Data System (ADS)

    Thomas, Y. B.

    2015-12-01

    Farmers in Burkina Faso are among the most exposed to climate change/ climate variability, as their livelihoods are greatly linked to climate hazards. Rainfall and in some extent temperature are among the inputs farmers use to take decisions in their farming activities. A better understanding of factors that shape farmers' perceptions of climate change and decision to adapt farming practices is needed to take appropriate measures. In the current study farmers' perception of climate change and climate variability- specifically, changes in rainfall and temperature- were compared to historical recorded climate data. Primary data was collected through village focus-group surveys and household surveys. Nine Focus Group Discussions (FGDs) were conducted in the study areas' villages; 450 households were also selected randomly from three locations and sampled out through a multi-stage sampling procedure. Secondary data on the historical precipitation and temperature of Burkina Faso from 1960 to 2012 was obtained from the National Meteorological Service of Burkina Faso (DGM) and the Royal Netherlands Meteorological Institute. Standardized Precipitation Index (SPI) and temperature anomalies methodology have been used to assess anomalies in rainfall and temperature covering a period of 48 years, from 1964 to 2011; and Mann-Kendall test and Theil-Sen slope estimator to assess the significance of the trends and the Theil-Sen slope estimator is used to identify their magnitude. The analysis of farmers' perceptions of climate change indicates that most farmers perceived a declining trend of precipitation and an increasing trend of temperature in all areas. Results from recorded climate data's analysis, revealed contrasting evidence, while that farmers' perception of temperature match with historical data, their perception of rainfall evolution were not always corroboted by scientific evidence.

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

    SciTech Connect

    Malygin, V.M.

    1995-06-01

    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.

  1. North American extreme temperature events and related large scale meteorological patterns: A review of statistical methods, dynamics, modeling, and trends

    SciTech Connect

    Grotjahn, Richard; Black, Robert; Leung, Ruby; Wehner, Michael F.; Barlow, Mathew; Bosilovich, Michael; Gershunov, Alexander; Gutowski, Jr., William J.; Gyakum, John R.; Katz, Richard W.; Lee, Yun -Young; Lim, Young -Kwon; Prabhat, -

    2015-05-22

    This paper reviews research approaches and open questions regarding data, statistical analyses, dynamics, modeling efforts, and trends in relation to temperature extremes. Our specific focus is upon extreme events of short duration (roughly less than 5 days) that affect parts of North America. These events are associated with large scale meteorological patterns (LSMPs). Methods used to define extreme events statistics and to identify and connect LSMPs to extreme temperatures are presented. Recent advances in statistical techniques can connect LSMPs to extreme temperatures through appropriately defined covariates that supplements more straightforward analyses. A wide array of LSMPs, ranging from synoptic to planetary scale phenomena, have been implicated as contributors to extreme temperature events. Current knowledge about the physical nature of these contributions and the dynamical mechanisms leading to the implicated LSMPs is incomplete. There is a pressing need for (a) systematic study of the physics of LSMPs life cycles and (b) comprehensive model assessment of LSMP-extreme temperature event linkages and LSMP behavior. Generally, climate models capture the observed heat waves and cold air outbreaks with some fidelity. However they overestimate warm wave frequency and underestimate cold air outbreaks frequency, and underestimate the collective influence of low-frequency modes on temperature extremes. Climate models have been used to investigate past changes and project future trends in extreme temperatures. Overall, modeling studies have identified important mechanisms such as the effects of large-scale circulation anomalies and land-atmosphere interactions on changes in extreme temperatures. However, few studies have examined changes in LSMPs more specifically to understand the role of LSMPs on past and future extreme temperature changes. Even though LSMPs are resolvable by global and regional climate models, they are not necessarily well simulated so more

  2. North American extreme temperature events and related large scale meteorological patterns: A review of statistical methods, dynamics, modeling, and trends

    DOE PAGESBeta

    Grotjahn, Richard; Black, Robert; Leung, Ruby; Wehner, Michael F.; Barlow, Mathew; Bosilovich, Michael; Gershunov, Alexander; Gutowski, Jr., William J.; Gyakum, John R.; Katz, Richard W.; et al

    2015-05-22

    This paper reviews research approaches and open questions regarding data, statistical analyses, dynamics, modeling efforts, and trends in relation to temperature extremes. Our specific focus is upon extreme events of short duration (roughly less than 5 days) that affect parts of North America. These events are associated with large scale meteorological patterns (LSMPs). Methods used to define extreme events statistics and to identify and connect LSMPs to extreme temperatures are presented. Recent advances in statistical techniques can connect LSMPs to extreme temperatures through appropriately defined covariates that supplements more straightforward analyses. A wide array of LSMPs, ranging from synoptic tomore » planetary scale phenomena, have been implicated as contributors to extreme temperature events. Current knowledge about the physical nature of these contributions and the dynamical mechanisms leading to the implicated LSMPs is incomplete. There is a pressing need for (a) systematic study of the physics of LSMPs life cycles and (b) comprehensive model assessment of LSMP-extreme temperature event linkages and LSMP behavior. Generally, climate models capture the observed heat waves and cold air outbreaks with some fidelity. However they overestimate warm wave frequency and underestimate cold air outbreaks frequency, and underestimate the collective influence of low-frequency modes on temperature extremes. Climate models have been used to investigate past changes and project future trends in extreme temperatures. Overall, modeling studies have identified important mechanisms such as the effects of large-scale circulation anomalies and land-atmosphere interactions on changes in extreme temperatures. However, few studies have examined changes in LSMPs more specifically to understand the role of LSMPs on past and future extreme temperature changes. Even though LSMPs are resolvable by global and regional climate models, they are not necessarily well simulated so

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

    PubMed Central

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

    2012-01-01

    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

  4. A new mean-extreme vector for the trends of temperature and precipitation over China during 1960-2013

    NASA Astrophysics Data System (ADS)

    Lyra, G. B.; Oliveira-Júnior, J. F.; Gois, G.; Cunha-Zeri, G.; Zeri, M.

    2016-06-01

    A mean-extreme (M-E) vector is defined to combine the changes of climate means and extremes. The direction of the vertical axis represents changes in means, whereas the direction of the horizontal axis represents changes in extremes. Therefore, the M-E vector can clearly reflect both the amplitude and direction of changes in climate means and extremes. Nine types of M-E vectors are defined. They are named as MuEu, MuEd, MuEz, MdEu, MdEd, MdEz, MzEu, MzEd, and MzEz. Here M and E stand for climate means and extremes, respectively, whereas u, d, and z indicate an upward, downward trend and no trend, respectively. Both temperature mean and extremely high temperature days are consistently increased (MuEu) in nearly whole China throughout four seasons. However, the MuEd-type vector dominates in some regions. The MuEd-type vector appears over the Huang Huai river basin in spring, summer and winter. For the M-E vector of temperature mean and extremely low temperature days, the MuEd-type spreads the entire China for all seasons. The M-E vector for precipitation mean and the extreme precipitation days possesses identical trends (MuEu or MdEd) despite of seasons. The MuEu-type dominates in northeastern China and west of 105°E in spring, northwestern and central/southern China in summer, west of 100°E and northeastern China in autumn, and nearly whole China in winter. Precipitation mean and extreme precipitation days are all decreased (MdEd) in the rest of China for all reasons. The trends relationship in means and extremes over China presented herein could provide a scientific foundation to predict change of extremes using change of mean as the predictor.

  5. Recent Reversal of the Upper-Tropospheric Temperature Trend and its Role in Intensifying the East Asian Summer Monsoon

    NASA Astrophysics Data System (ADS)

    Zhao, Siyao; Li, Jian; Yu, Rucong; Chen, Haoming

    2015-07-01

    At the beginning of the 21st century, the July and August (JA) mean upper-tropospheric temperature over East Asia shows a significant increasing trend, contrary to the decreasing trend in the late 1970 s. The largest warming center is over northern China (between 30°N-45°N and 85°E-120°E) around 300 hPa. Together with the temperature rising, the geo-potential height rises above the warming center and drops below, which connects closely to a correspondingly significant decadal shift of the general circulation over East Asia. In the upper-level of the troposphere, an anomalous anti-cyclone dominates, and the 200-hPa westerly jet strengthens due to the increasing pole-ward geo-potential height gradient. In the lower-troposphere, the anomalous southerly wind increases around Yangtze River Valley and the East Asian summer monsoon intensifies. The integrated circulation changes seriously impact summer precipitation over East Asia. The so-called “southern flood and northern drought” (SFND) pattern since the 1970 s over eastern China has changed. As the cooling center in the 1970 s moves southward, the dry belt moves southward as well. A wet belt dominates the Huaihe River Valley after the temperature trend reversal at 2005 while southern China experiences a dry condition.

  6. Recent Reversal of the Upper-Tropospheric Temperature Trend and its Role in Intensifying the East Asian Summer Monsoon.

    PubMed

    Zhao, Siyao; Li, Jian; Yu, Rucong; Chen, Haoming

    2015-01-01

    At the beginning of the 21st century, the July and August (JA) mean upper-tropospheric temperature over East Asia shows a significant increasing trend, contrary to the decreasing trend in the late 1970 s. The largest warming center is over northern China (between 30°N-45°N and 85°E-120°E) around 300 hPa. Together with the temperature rising, the geo-potential height rises above the warming center and drops below, which connects closely to a correspondingly significant decadal shift of the general circulation over East Asia. In the upper-level of the troposphere, an anomalous anti-cyclone dominates, and the 200-hPa westerly jet strengthens due to the increasing pole-ward geo-potential height gradient. In the lower-troposphere, the anomalous southerly wind increases around Yangtze River Valley and the East Asian summer monsoon intensifies. The integrated circulation changes seriously impact summer precipitation over East Asia. The so-called "southern flood and northern drought" (SFND) pattern since the 1970 s over eastern China has changed. As the cooling center in the 1970 s moves southward, the dry belt moves southward as well. A wet belt dominates the Huaihe River Valley after the temperature trend reversal at 2005 while southern China experiences a dry condition. PMID:26135966

  7. Changing trends and abrupt features of extreme temperature in mainland China during 1960 to 2010

    NASA Astrophysics Data System (ADS)

    Fang, S.; Qi, Y.; Han, G.; Zhou, G.

    2015-05-01

    A few researches based on the 10th (90th) percentiles as thresholds had presented to assess moderate extremes in China. However, there has been very little research reported on the occurrences of high extremes warm days (TX95p and TX99p) and cold nights (TN05p and TN01p) according to 95th or 99th (5th or 1st) percentiles which has more directly impacts on society and ecosystem systems. The study showed: (1) the frequencies of TX95p and TX99p averagely increased by 1.80 days/10 a and 0.62 days/10 a respectively in all stations of mainland China, and TX95p in 50.42 % and TX99p in 58.21 % of the stations increased significantly, but TN05p in 83.76 % and TN01p in 76.48 % of stations decreased significantly, and the frequencies of TN05p and TN01p averagely decreased by 3.18 days/10 a and 1.01 days/10 a respectively in all stations, (2) except in Central China, other regions of China showed an increasing trend in TX95p and TX99p, but vast majority of the mainland China showed a decreasing trend in TN5p and TN01p; and (3) the trends of TX95p and TX99p mutations time were in about 1990s or 2000s, but the trends of TN05p and TN01p has mutated in the late 1970s and early 1980s. After the mutation, the increasing trend of warm day and hot day is greater than before in most regions which indicated that more potential risk of heatwaves in future, but the decreasing trend of cold day and frozen day is not enlarge than before.

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

    SciTech Connect

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

    2014-10-21

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

  9. Relationship between sunshine duration and temperature trends across Europe since the second half of the twentieth century

    NASA Astrophysics Data System (ADS)

    Besselaar, E. J. M.; Sanchez-Lorenzo, A.; Wild, M.; Klein Tank, A. M. G.; Laat, A. T. J.

    2015-10-01

    Global radiation is a fundamental source of energy in the climate system. A significant impact of global radiation on temperature change is expected due to the widespread dimming/brightening phenomenon observed since the second half of the twentieth century. This work describes the analysis of 312 stations with sunshine duration (SD) series, a proxy for global radiation, and temperature series in the European Climate Assessment & Dataset (ECA&D) with data over the period 1961-2010. The relationship between SD and temperature series is analyzed for four temperature variables: maximum (Tmax), minimum (Tmin), mean temperature (Tmean), and diurnal temperature range (DTR). The analyses are performed on annual and seasonal basis. The results show strong positive correlations between SD and temperatures over Europe, with highest correlation for DTR and Tmax during the summer period. These results confirm the strong relationship between SD and temperature trends over Europe since the second half of the twentieth century. This study supports previous suggestions that dimming (brightening) has partially decreased (increased) temperatures thereby modulating the greenhouse gas induced warming rates over Europe.

  10. Ostracod body size trends do not follow either Bergmann's rule or Cope's rule during periods of constant temperature increase

    NASA Astrophysics Data System (ADS)

    Xu, Y.; Seshadri, P.; Amin, V.; Heim, N. A.; Payne, J.

    2013-12-01

    Over time, organisms have adapted to changing environments by evolving to be larger or smaller. Scientists have described body-size trends using two generalized theories. Bergmann's rule states that body size is inversely related to temperature, and Cope's rule establishes an increase over time. Cope's rule has been hypothesized as a temporal manifestation of Bergmann's rule, as the temperature of the Earth has consistently decreased over time and mean body size has increased. However, during times of constant temperature increase, Bergmann's rule and Cope's rule predict opposite effects on body size. Our goal was to clarify this relationship using both accessible proxies of historic temperature - atmospheric CO2 levels and paleo-latitude. We measured ostracod lengths throughout the Paleozoic and Mesozoic eras (using the Catalogue of Ostracoda) and utilized ostracod latitudinal information from the Paleobiology Database. By closely studying body-size trends during four time periods of constant CO2 increase across spectrums of time and latitude, we were able to compare the effects of Cope's and Bergmann's rule. The correlation, p-values, and slopes of each of our graphs showed that there is no clear relationship between body size and each of these rules in times of temperature increase, both latitudinally and temporally. Therefore, both Cope's and Bergmann's rule act on marine ostracods and no rule is dominant, though our results more strongly disprove the latitudinal variation in ostracod size.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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

  12. Non-Linear Association between Exposure to Ambient Temperature and Children’s Hand-Foot-and-Mouth Disease in Beijing, China

    PubMed Central

    Xu, Meimei; Yu, Weiwei; Tong, Shilu; Jia, Lei; Liang, Fengchao; Pan, Xiaochuan

    2015-01-01

    Background Hand, foot and mouth disease (HFMD) was listed as a notifiable communicable disease in 2008 and is an emerging public health problem in China, especially for children. However, few data are available on the risk assessment of the potential reasons for HFMD in Beijing. This study examined the association of temperature with the incidence of children’s HFMD in Beijing at the daily scale for the first time. Methods A newly developed case-crossover design with a distributed lag nonlinear model (DLNM) was used to assess the delayed and cumulative associations of daily temperature with gender- and age-specific HFMD in Beijing, China, during 2010–2012. Relative humidity, day of the week, public holiday, season and long-term trends were controlled in the model. Results Among the total of 113,475 cases, the ratio between males and females was 1.52:1. HFMD was more prevalent in May-July. The temperature-HFMD relationships were non-linear in most age groups except for children aged 6–15 years, with a peak at 25.0~27.5°C. The high-temperature risks were greater, appeared earlier and lasted longer than the low-temperature risks. The relative risks for female children and those aged 6–15 years were higher than those among other groups. Conclusion Rising temperatures increased the incidence of children’s HFMD, with the largest association at 25.0~27.5°C. Females and children aged 6–15 years were more vulnerable to changes in temperature with regard to the transmission of HFMD than males and other age groups, respectively. Further studies are warranted to confirm these findings in other populations. PMID:26010147

  13. Recent trends and variations in Baltic Sea temperature, salinity, stratification and circulation

    NASA Astrophysics Data System (ADS)

    Elken, Jüri; Lehmann, Andreas; Myrberg, Kai

    2015-04-01

    The presentation highlights the results of physical oceanography from BACC II (Second BALTEX Assessment of Climate Change for the Baltic Sea basin) book based on the review of recent literature published until 2013. We include also information from some more recent publications. A recent warming trend in sea surface waters has been clearly demonstrated by all available methods: in-situ measurements, remote sensing data and modelling tools. In particular, remote sensing data for the period 1990-2008 indicate that the annual mean SST has increased even by 1°C per decade, with the greatest increase in the northern Bothnian Bay and also with large increases in the Gulf of Finland, the Gulf of Riga, and the northern Baltic Proper. Although the increase in the northern areas is affected by the recent decline in the extent and duration of sea ice, and corresponding changes in surface albedo, warming is still evident during all seasons and with the greatest increase occurring in summer. The least warming of surface waters (0.3-0.5°C per decade) occurred northeast of Bornholm Island up to and along the Swedish coast, probably owing to an increase in the frequency of coastal upwelling forced by the westerly wind events. Comparing observations with the results of centennial-scale modelling, recent changes in sea water temperature appear to be within the range of the variability observed during the past 500 years. Overall salinity pattern and stratification conditions are controlled by river runoff, wind conditions, and salt water inflows through the Danish straits. The mean top-layer salinity is mainly influenced by the accumulated river runoff, with higher salinity during dry periods and lower salinity during wet periods. Observations reveal a low-salinity period above the halocline starting in the 1980s. The strength of stratification and deep salinity are reduced when the mean zonal wind stress increases, as it occurred since 1987. Major Baltic Inflows of highly saline

  14. 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)

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

    2014-11-01

    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.

  15. Investigating the Equilibrium Melting Temperature of Polyethylene Using the Non-Linear Hoffman-Weeks Analysis: Effect of Molecular Weight

    NASA Astrophysics Data System (ADS)

    Mohammadi, Hadi; Marand, Herve

    The limiting equilibrium melting temperature for infinite molar mass linear polyethylene, Tmo , has been a point of controversy for about five decades. On one hand, Broadhurst and Flory-Vrij extrapolated melting data for short alkanes to a value of ca. 145oC. On the other hand, Wunderlich proposed a value of 141oC from melting studies of extended-chain PE crystals formed under high pressure. While a difference in Tmo by 4oC might seem superfluous, it has significant implication for the analysis of the temperature and chain length dependences of crystal growth kinetic data. In this work we estimate the equilibrium melting temperatures, Tm for three linear narrow molecular weight distribution polyethylenes using the non-linear Hoffman-Weeks treatment. The resulting Tm values thus obtained are significantly lower than these predicted by the Flory-Vrij treatment and are within experimental uncertainty indistinguishable from those reported by Wunderlich and Hikosaka et al. Our results also suggest that the constant C2 in the expression for the undercooling dependence of the initial lamellar thickness (lg*= C1/ ΔT + C2) increases linearly with chain length.

  16. A new marker for sea surface temperature trend during the last centuries in temperate areas: Vermetid reef

    NASA Astrophysics Data System (ADS)

    Silenzi, Sergio; Antonioli, Fabrizio; Chemello, Renato

    2004-01-01

    The presence of Vermetid reefs in temperate waters, their diffusion in the Mediterranean Sea, and the possibility of performing 14C ages allowed the use of Vermetids as an indicator of sea level changes. We present new data on sea climate trend fluctuations that could be interpreted as Sea Surface Temperature (SST) variations, recorded on Vermetid ( Dendropoma petraeum) reefs, by means of isotopic analysis. The isotopic records show positive values of the δ18O relative to present-day values in the period between 1600 and 1850 AD; this deviation occurs in association with the climatic cooling event known as Little Ice Age (LIA). Subsequently, we can observe the warming trend that characterized the last century. These preliminary results indicate that Vermetids could be considered a new SST proxy-data for the Mediterranean Sea and, more generally, for temperate areas.

  17. Temperature sensitivity trends and multi-stimuli sensitive behavior in amphiphilic oligomers.

    PubMed

    Wang, Feng; Klaikherd, Akamol; Thayumanavan, S

    2011-08-31

    A series of oligomers, containing oligo(ethylene glycol) (OEG) moieties, with the same composition of amphiphilic functionalities has been designed, synthesized, and characterized on the basis of their temperature-sensitive behavior. The non-covalent amphiphilic aggregates, formed from these molecules, influence their temperature sensitivity. Covalent tethering of the amphiphilic units also has a significant influence on their temperature sensitivity. The lower critical solution temperatures of these oligomers show increasingly sharp transitions with increasing numbers of OEG functional groups, indicating enhanced cooperativity in dehydration of the OEG moieties when they are covalently tethered. These molecules were also engineered to be concurrently sensitive to enzymatic reaction and pH. This possibility was investigated using porcine liver esterase as the enzyme; we show that enzymatic action on the pentamer lowers its temperature sensitivity. The product moiety from the enzymatic reaction also gives the amphiphilic oligomer a pH-dependent temperature sensitivity. PMID:21739959

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    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).

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

    NASA Technical Reports Server (NTRS)

    Mallon, Joseph R., Jr.

    1992-01-01

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

  20. 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...

  1. The importance of the covariation of the geographical distribution of SSTs and deep convection for tropical tropospheric temperature trends 1980-present

    NASA Astrophysics Data System (ADS)

    Fueglistaler, Stephan; Flannaghan, Thomas; Po-Chedley, Stephen; Held, Isaac; Radley, Claire; Zhao, Ming; Wyman, Bruce

    2016-04-01

    Enhanced upper tropospheric warming relative to the surface in the tropics is a prominent feature of numerical model simulations, but it has been suggested that models overestimate this warming compared to observations for the period 1980 to present. Here, we focus on the factors controlling atmospheric temperature trends in numerical model calculations with prescribed Sea Surface Temperatures (SSTs). CMIP5 model runs show a remarkably large spread in tropical temperature trends over the period 1980-2008 despite being forced with observed SSTs. Here, we show that the model trends are consistent with the atmospheric temperature profile being tightly constrained by the surface layer conditions in regions of deep convection. Large trend differences arise from the use of two different SST data, the "HURRELL" and the "HadISST1" data. These two SSTs have very similar tropical average trends, but differ substantially in the warmest percentiles where most deep convection occurs. The models' temperature trend differences in the tropical troposphere reflect the trend differences in the regions of highest SSTs. Further, we show that trend differences in model calculations using identical SSTs is strongly related to differences in the geographical pattern of strong precipitation (used as a simple proxy for deep convection) between models, and between ensemble runs of a model. The time series of precipitation weighted SSTs can explain more than half of the variance in temperature trends. The variance in trends between ensemble members of the same model, and between ensemble means of different models, is similar. However, the decrease in variance upon averaging over ensemble members is modest compared to the expected scaling for independent samples, which provides evidence for systematic differences between models in their response in the geographical distribution of convection to changes in SST patterns.

  2. Daily temperature and mortality: a study of distributed lag non-linear effect and effect modification in Guangzhou

    PubMed Central

    2012-01-01

    Background Although many studies have documented health effects of ambient temperature, little evidence is available in subtropical or tropical regions, and effect modifiers remain uncertain. We examined the effects of daily mean temperature on mortality and effect modification in the subtropical city of Guangzhou, China. Methods A Poisson regression model combined with distributed lag non-linear model was applied to assess the non-linear and lag patterns of the association between daily mean temperature and mortality from 2003 to 2007 in Guangzhou. The case-only approach was used to determine whether the effect of temperature was modified by individual characteristics, including sex, age, educational attainment and occupation class. Results Hot effect was immediate and limited to the first 5 days, with an overall increase of 15.46% (95% confidence interval: 10.05% to 20.87%) in mortality risk comparing the 99th and the 90th percentile temperature. Cold effect persisted for approximately 12 days, with a 20.39% (11.78% to 29.01%) increase in risk comparing the first and the 10th percentile temperature. The effects were especially remarkable for cardiovascular and respiratory mortality. The effects of both hot and cold temperatures were greater among the elderly. Females suffered more from hot-associated mortality than males. We also found significant effect modification by educational attainment and occupation class. Conclusions There are significant mortality effects of hot and cold temperatures in Guangzhou. The elderly, females and subjects with low socioeconomic status have been identified as especially vulnerable to the effect of ambient temperatures. PMID:22974173

  3. The effect of changes in sea surface temperature on linear growth of Porites coral in Ambon Bay

    SciTech Connect

    Corvianawatie, Corry Putri, Mutiara R.; Cahyarini, Sri Y.

    2015-09-30

    Coral is one of the most important organisms in the coral reef ecosystem. There are several factors affecting coral growth, one of them is changes in sea surface temperature (SST). The purpose of this research is to understand the influence of SST variability on the annual linear growth of Porites coral taken from Ambon Bay. The annual coral linear growth was calculated and compared to the annual SST from the Extended Reconstructed Sea Surface Temperature version 3b (ERSST v3b) model. Coral growth was calculated by using Coral X-radiograph Density System (CoralXDS) software. Coral sample X-radiographs were used as input data. Chronology was developed by calculating the coral’s annual growth bands. A pair of high and low density banding patterns observed in the coral’s X-radiograph represent one year of coral growth. The results of this study shows that Porites coral extents from 2001-2009 and had an average growth rate of 1.46 cm/year. Statistical analysis shows that the annual coral linear growth declined by 0.015 cm/year while the annual SST declined by 0.013°C/year. SST and the annual linear growth of Porites coral in the Ambon Bay is insignificantly correlated with r=0.304 (n=9, p>0.05). This indicates that annual SST variability does not significantly influence the linear growth of Porites coral from Ambon Bay. It is suggested that sedimentation load, salinity, pH or other environmental factors may affect annual linear coral growth.

  4. The effect of changes in sea surface temperature on linear growth of Porites coral in Ambon Bay

    NASA Astrophysics Data System (ADS)

    Corvianawatie, Corry; Cahyarini, Sri Y.; Putri, Mutiara R.

    2015-09-01

    Coral is one of the most important organisms in the coral reef ecosystem. There are several factors affecting coral growth, one of them is changes in sea surface temperature (SST). The purpose of this research is to understand the influence of SST variability on the annual linear growth of Porites coral taken from Ambon Bay. The annual coral linear growth was calculated and compared to the annual SST from the Extended Reconstructed Sea Surface Temperature version 3b (ERSST v3b) model. Coral growth was calculated by using Coral X-radiograph Density System (CoralXDS) software. Coral sample X-radiographs were used as input data. Chronology was developed by calculating the coral's annual growth bands. A pair of high and low density banding patterns observed in the coral's X-radiograph represent one year of coral growth. The results of this study shows that Porites coral extents from 2001-2009 and had an average growth rate of 1.46 cm/year. Statistical analysis shows that the annual coral linear growth declined by 0.015 cm/year while the annual SST declined by 0.013°C/year. SST and the annual linear growth of Porites coral in the Ambon Bay is insignificantly correlated with r=0.304 (n=9, p>0.05). This indicates that annual SST variability does not significantly influence the linear growth of Porites coral from Ambon Bay. It is suggested that sedimentation load, salinity, pH or other environmental factors may affect annual linear coral growth.

  5. Trends and abrupt changes in 104 years of ice cover and water temperature in a dimictic lake in response to air temperature, wind speed, and water clarity drivers

    NASA Astrophysics Data System (ADS)

    Magee, Madeline R.; Wu, Chin H.; Robertson, Dale M.; Lathrop, Richard C.; Hamilton, David P.

    2016-05-01

    The one-dimensional hydrodynamic ice model, DYRESM-WQ-I, was modified to simulate ice cover and thermal structure of dimictic Lake Mendota, Wisconsin, USA, over a continuous 104-year period (1911-2014). The model results were then used to examine the drivers of changes in ice cover and water temperature, focusing on the responses to shifts in air temperature, wind speed, and water clarity at multiyear timescales. Observations of the drivers include a change in the trend of warming air temperatures from 0.081 °C per decade before 1981 to 0.334 °C per decade thereafter, as well as a shift in mean wind speed from 4.44 m s-1 before 1994 to 3.74 m s-1 thereafter. Observations show that Lake Mendota has experienced significant changes in ice cover: later ice-on date(9.0 days later per century), earlier ice-off date (12.3 days per century), decreasing ice cover duration (21.3 days per century), while model simulations indicate a change in maximum ice thickness (12.7 cm decrease per century). Model simulations also show changes in the lake thermal regime of earlier stratification onset (12.3 days per century), later fall turnover (14.6 days per century), longer stratification duration (26.8 days per century), and decreasing summer hypolimnetic temperatures (-1.4 °C per century). Correlation analysis of lake variables and driving variables revealed ice cover variables, stratification onset, epilimnetic temperature, and hypolimnetic temperature were most closely correlated with air temperature, whereas freeze-over water temperature, hypolimnetic heating, and fall turnover date were more closely correlated with wind speed. Each lake variable (i.e., ice-on and ice-off dates, ice cover duration, maximum ice thickness, freeze-over water temperature, stratification onset, fall turnover date, stratification duration, epilimnion temperature, hypolimnion temperature, and hypolimnetic heating) was averaged for the three periods (1911-1980, 1981-1993, and 1994-2014) delineated by

  6. [The Clinical Application Status and Development Trends of Hydrogen Peroxide Low Temperature Plasma Sterilizers].

    PubMed

    Zhuang, Min; Zheng, Yunxin; Chen, Ying; Hou, Bin; Xu, Zitian

    2016-01-01

    The hydrogen peroxide low temperature plasma sterilization technology solved the problems of thermo-sensitive materials' disinfection and sterilization based on its development and unique characteristics. This paper introduced the researches of clinical application quality control, and showed the hydrogen peroxide low temperature plasma sterilizers were being widely used in hospitals and highly recognized. According to the clinical data and the literatures of the domestic equipment in preliminary application, it could be concluded that the technology maturity of domestic hydrogen peroxide low temperature plasma sterilizers was in a high level. The advantages of using domestic hydrogen peroxide low temperature plasma sterilizers to do disinfection and sterilization included lower cost, safer, faster and non-toxic, etc. Also the management system should be improved and the clinical staff should master the technical essentials, obey the procedures strictly, verify periodically and offer full monitoring to upgrade the quality of sterilization. PMID:27197500

  7. High Precision Piezoelectric Linear Motors for Operations at Cryogenic Temperatures and Vacuum

    NASA Technical Reports Server (NTRS)

    Wong, D.; Carman, G.; Stam, M.; Bar-Cohen, Y.; Sen, A.; Henry, P.; Bearman, G.; Moacanin, J.

    1995-01-01

    The use of an electromechanical device for optically positioning a mirror system during the pre-project phase of the Pluto Fast Flyby mission was evaluated at JPL. The device under consideration was a piezoelectric driven linear motor functionally dependent upon a time varying electric field which induces displacements ranging from submicrons to millimeters with positioning accuracy within nanometers.

  8. A Temperature-Dependent, Linearly Interpolable, Tabulated Cross Section Library Based on ENDF/B-VI, Release 4.

    Energy Science and Technology Software Center (ESTSC)

    1997-09-09

    Version 00 As distributed, the original evaluated data includes cross sections represented in the form of a combination of resonance parameters and/or tabulated energy dependent cross sections, nominally at 0 Kelvin temperature. For use in applications, these ENDF/B-VI, Release 4 data were processed into the form of temperature dependent cross sections at eight temperatures between 0 and 2100 Kelvin, in steps of 300 Kelvin. At each temperature the cross sections are tabulated and linearly interpolablemore » in energy. The library contains data for 321 evaluations. The CCC-638/TART96 code package is recommended for use with these data. Codes within TART96 can be used to display these data or to run calculations using these data.« less

  9. Computing alignment and orientation of non-linear molecules at room temperatures using random phase wave functions

    NASA Astrophysics Data System (ADS)

    Kallush, Shimshon; Fleischer, Sharly; Ultrafast terahertz molecular dynamics Collaboration

    2015-05-01

    Quantum simulation of large open systems is a hard task that demands huge computation and memory costs. The rotational dynamics of non-linear molecules at high-temperature under external fields is such an example. At room temperature, the initial density matrix populates ~ 104 rotational states, and the whole coupled Hilbert space can reach ~ 106 states. Simulation by neither the direct density matrix nor the full basis set of populated wavefunctions is impossible. We employ the random phase wave function method to represent the initial state and compute several time dependent and independent observables such as the orientation and the alignment of the molecules. The error of the method was found to scale as N- 1 / 2, where N is the number of wave function realizations employed. Scaling vs. the temperature was computed for weak and strong fields. As expected, the convergence of the method increase rapidly with the temperature and the field intensity.

  10. North American extreme temperature events and related large scale meteorological patterns: a review of statistical methods, dynamics, modeling, and trends

    NASA Astrophysics Data System (ADS)

    Grotjahn, Richard; Black, Robert; Leung, Ruby; Wehner, Michael F.; Barlow, Mathew; Bosilovich, Mike; Gershunov, Alexander; Gutowski, William J.; Gyakum, John R.; Katz, Richard W.; Lee, Yun-Young; Lim, Young-Kwon; Prabhat

    2016-02-01

    The objective of this paper is to review statistical methods, dynamics, modeling efforts, and trends related to temperature extremes, with a focus upon extreme events of short duration that affect parts of North America. These events are associated with large scale meteorological patterns (LSMPs). The statistics, dynamics, and modeling sections of this paper are written to be autonomous and so can be read separately. Methods to define extreme events statistics and to identify and connect LSMPs to extreme temperature events are presented. Recent advances in statistical techniques connect LSMPs to extreme temperatures through appropriately defined covariates that supplement more straightforward analyses. Various LSMPs, ranging from synoptic to planetary scale structures, are associated with extreme temperature events. Current knowledge about the synoptics and the dynamical mechanisms leading to the associated LSMPs is incomplete. Systematic studies of: the physics of LSMP life cycles, comprehensive model assessment of LSMP-extreme temperature event linkages, and LSMP properties are needed. Generally, climate models capture observed properties of heat waves and cold air outbreaks with some fidelity. However they overestimate warm wave frequency and underestimate cold air outbreak frequency, and underestimate the collective influence of low-frequency modes on temperature extremes. Modeling studies have identified the impact of large-scale circulation anomalies and land-atmosphere interactions on changes in extreme temperatures. However, few studies have examined changes in LSMPs to more specifically understand the role of LSMPs on past and future extreme temperature changes. Even though LSMPs are resolvable by global and regional climate models, they are not necessarily well simulated. The paper concludes with unresolved issues and research questions.

  11. The forcing of anthropogenic aerosols and greenhouse gases on sub-thermocline temperature trends in the southern subtropical Indian Ocean

    NASA Astrophysics Data System (ADS)

    Cowan, T.; Purich, A.; Cai, W.; Rotstayn, L. D.; England, M. H.

    2013-12-01

    In the late twentieth century, the sub-thermocline waters of the southern tropical and subtropical Indian Ocean (IO) 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 IO experienced a rapid temperature trend reversal. In the context of understanding the causes of the sub-thermocline temperature changes, we use a suite of Coupled Model Intercomparison Project phase 5 (CMIP5) models forced with natural and anthropogenic radiative forcings and as well as individual forcing runs. We use these to: (i) examine whether the sub-thermocline cooling and/or rapid warming of the tropical/subtropical IO is anthropogenic or naturally forced; and (ii) assess future projections of the sub-thermocline temperatures in the mid twenty-first century from available model output. Results suggest that the late twentieth century sub-thermocline cooling of the southern IO 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 middle of the twenty-first century. The timing of the commencement of this warming appears dependent on the total change in anthropogenic aerosol levels, with models exhibiting a strong (weak) decline in future aerosols simulating a greater (weaker) magnitude of warming after the occurrence of peak aerosols. The role of greenhouse gases in forcing sub-thermocline temperature trends in the IO in the future remains to be determined. Despite this, it is clear is that as human generated aerosols continue to decline over the coming century, the subsurface ocean circulation will respond accordingly through an acceleration in the warming.

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

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

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

    USGS Publications Warehouse

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

    2011-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2003-12-01

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

  16. The Relation Between Atmospheric Humidity and Temperature Trends for Stratospheric Water

    NASA Technical Reports Server (NTRS)

    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

    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

  17. High Precision Piezoelectric Linear Motors for Operations at Cryogenic Temperatures and Vacuum

    NASA Technical Reports Server (NTRS)

    Wong, D.; Carman, G.; Stam, M.; Bar-Cohen, Y.; Sen, A.; Henry, P.; Bearman, G.; Moacanin, J.

    1995-01-01

    The Jet Propulsion Laboratory evaluated the use of an electromechanical device for optically positioning a mirror system during the pre-project phase of the Pluto-Fast-Flyby (PFF) mission. The device under consideration was a piezoelectric driven linear motor functionally dependent upon a time varying electric field which induces displacements ranging from submicrons to millimeters with positioning accuracy within nanometers. Using a control package, the mirror system provides image motion compensation and mosaicking capabilities. While this device offers unique advantages, there were concerns pertaining to its operational capabilities for the PFF mission. The issues include irradiation effects and thermal concerns. A literature study indicated that irradiation effects will not significantly impact the linear motor's operational characteristics. On the other hand, thermal concerns necessitated an in depth study.

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

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

    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

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

    ERIC Educational Resources Information Center

    Radtka, Catherine

    2013-01-01

    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…

  20. Multisite multivariate modeling of daily precipitation and temperature in the Canadian Prairie Provinces using generalized linear models

    NASA Astrophysics Data System (ADS)

    Asong, Zilefac E.; Khaliq, M. N.; Wheater, H. S.

    2016-02-01

    Based on the Generalized Linear Model (GLM) framework, a multisite stochastic modelling approach is developed using daily observations of precipitation and minimum and maximum temperatures from 120 sites located across the Canadian Prairie Provinces: Alberta, Saskatchewan and Manitoba. Temperature is modeled using a two-stage normal-heteroscedastic model by fitting mean and variance components separately. Likewise, precipitation occurrence and conditional precipitation intensity processes are modeled separately. The relationship between precipitation and temperature is accounted for by using transformations of precipitation as covariates to predict temperature fields. Large scale atmospheric covariates from the National Center for Environmental Prediction Reanalysis-I, teleconnection indices, geographical site attributes, and observed precipitation and temperature records are used to calibrate these models for the 1971-2000 period. Validation of the developed models is performed on both pre- and post-calibration period data. Results of the study indicate that the developed models are able to capture spatiotemporal characteristics of observed precipitation and temperature fields, such as inter-site and inter-variable correlation structure, and systematic regional variations present in observed sequences. A number of simulated weather statistics ranging from seasonal means to characteristics of temperature and precipitation extremes and some of the commonly used climate indices are also found to be in close agreement with those derived from observed data. This GLM-based modelling approach will be developed further for multisite statistical downscaling of Global Climate Model outputs to explore climate variability and change in this region of Canada.

  1. Evaluation of the improved linear emissivity constraint temperature and emissivity separation method by using the simulated hyperspectral thermal infrared data

    NASA Astrophysics Data System (ADS)

    Wu, Hua; Li, Zhao-Liang; Tang, Bo-Hui; Tang, Rong-Lin

    2015-12-01

    In this study, an improved linear emissivity constraint temperature and emissivity separation (I-LECTES) method was first proposed to overcome the discontinuities problem of the retrieved land surface emissivities (LSEs) in the former linear emissivity constraint temperature and emissivity separation (LECTES) method. Consequently, the hyperspectral thermal infrared data were carefully simulated according to the configuration of Designs & Prototypes microFTIR Model 102, and were used to evaluate the performance of the I-LECTES method. Meanwhile, the I-LECTES method was also compared with the LECTES method. Different the atmosphere and surface circumstances were considered, as well as the different levels of noise equivalent temperature difference (NEΔT). The results showed that the proposed I-LECTES method is of a better accuracy compared with the LECTES method and has the characteristic of keeping the retrieved LSEs continuous, which sounds more reasonable. Because the noises in the ground measured radiance may have more effects on the accuracies of land surface temperature (LST) and LSEs than those in the atmospheric downwelling radiance, the noise in the ground measured radiance should be removed as much as possible to improve the accuracies of retrieved LST and LSEs. Furthermore, taken into account the lower retrieval accuracies for the cold and dry atmosphere, both the I-LECTES method and the LECTES method should be taken a full consideration. The proposed method is regarded to be promising because of its holding continuity and noise-immune.

  2. Cooling of daytime temperatures in coastal California air basins during 1969-2005: Monthly and extreme value trends

    NASA Astrophysics Data System (ADS)

    Gonzalez, J.; Bornstein, R. D.; Charland, A.; Gonzalez, J.

    2009-12-01

    Analysis of long-term (1969-2005) air temperatures in California (CA) during summer (June-August) previously showed an aggregate CA asymmetric warming, as daily minimum temperatures increased faster than daily maximum values Tmax. The spatial distributions of daily Tmax temperatures in the heavily urbanized South Coast and San Francisco Bay Area air basins were more complex pattern, with cooling at low-elevation coastal-areas and warming at inland areas. Our hypothesis was that this temperature pattern arose from a “reverse-reaction” to greenhouse gas induced global-warming, in that the global warming of inland areas resulted in an increased (cooling) sea breeze activity in coastal areas. These results appeared in the July 2009 issue of the J. of Climate. Extension of this analysis over the entire year now shows that the cooling trend in average Tmax values occurred during most months, with warming trends only during winter months. The largest rate of cooling, however, occurred in June (-0.95 K/decade), indicating that an earlier initiation of sea breeze activity may be the most important cooling factor, relative to increases in its intensity, duration, and/or penetration. Possible beneficial effects of the cooling were discussed (e.g., decreased maximum O3 and human thermal-stress levels), but as these impact would occur during periods of maximum Tmax values, the previous analysis was thus expanded to includes trends in the frequency of high Tmax values, i.e., 85, 90, 95, and 100oF. Results showed that all of these frequencies were decreasing, with rates decreasing with Tmax value (from -0.27 to -0.04 days/year, respectively). While this result is expected, as the frequency of occurrence decreases with Tmax value (from about 50 to about 3 per year, respectively), the percent decrease in frequency showed the opposite results, i.e., it was largest with the highest Tmax value (from -0.57 to -1.57 %/year, respectively). In addition, the rate of decrease of annual

  3. Geo-spatial analysis of temporal trends of temperature and its extremes over India using daily gridded (1°×1°) temperature data of 1969-2005

    NASA Astrophysics Data System (ADS)

    Chakraborty, Abhishek; Seshasai, M. V. R.; Rao, S. V. C. Kameswara; Dadhwal, V. K.

    2016-07-01

    Daily gridded (1°×1°) temperature data (1969-2005) were used to detect spatial patterns of temporal trends of maximum and minimum temperature (monthly and seasonal), growing degree days (GDDs) over the crop-growing season (kharif, rabi, and zaid) and annual frequencies of temperature extremes over India. The direction and magnitude of trends, at each grid level, were estimated using the Mann-Kendall statistics (α = 0.05) and further assessed at the homogeneous temperature regions using a field significance test (α=0.05). General warming trends were observed over India with considerable variations in direction and magnitude over space and time. The spatial extent and the magnitude of the increasing trends of minimum temperature (0.02-0.04 °C year-1) were found to be higher than that of maximum temperature (0.01-0.02 °C year-1) during winter and pre-monsoon seasons. Significant negative trends of minimum temperature were found over eastern India during the monsoon months. Such trends were also observed for the maximum temperature over northern and eastern parts, particularly in the winter month of January. The general warming patterns also changed the thermal environment of the crop-growing season causing significant increase in GDDs during kharif and rabi seasons across India. The warming climate has also caused significant increase in occurrences of hot extremes such as hot days and hot nights, and significant decrease in cold extremes such as cold days and cold nights.

  4. Trends of mean and extreme temperature indices since 1874 at low-elevation sites in the southern Alps

    NASA Astrophysics Data System (ADS)

    Brugnara, Yuri; Auchmann, Renate; Brönnimann, Stefan; Bozzo, Alessio; Berro, Daniele Cat; Mercalli, Luca

    2016-04-01

    We describe the recovery of three daily meteorological records for the southern Alps (Domodossola, Riva del Garda, and Rovereto), all starting in the second half of the nineteenth century. We use these new data, along with additional records, to study regional changes in the mean temperature and extreme indices of heat waves and cold spells frequency and duration over the period 1874-2015. The records are homogenized using subdaily cloud cover observations as a constraint for the statistical model, an approach that has never been applied before in the literature. A case study based on a record of parallel observations between a traditional meteorological window and a modern screen shows that the use of cloud cover can reduce the root-mean-square error of the homogenization by up to 30% in comparison to an unaided statistical correction. We find that mean temperature in the southern Alps has increased by 1.4°C per century over the analyzed period, with larger increases in daily minimum temperatures than maximum temperatures. The number of hot days in summer has more than tripled, and a similar increase is observed in duration of heat waves. Cold days in winter have dropped at a similar rate. These trends are mainly caused by climate change over the last few decades.

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

    NASA Astrophysics Data System (ADS)

    Oort, Abraham H.; Liu, Huanzhu

    1993-02-01

    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 63 stations. Excellent agreement is found with these earlier results as well as with an 11-year set of satellite-derived microwave sounding unit data. These detailed comparisons support the conclusion that the rawinsonde network can provide reliable estimates of the actual interseasonal hemispheric-scale temperature changes that have occurred between the earth's surface and about 20 km (50 mb) height since the 1950s.

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

    NASA Technical Reports Server (NTRS)

    Liu, W. T.

    1983-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Radtka, Catherine

    2013-04-01

    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.

  8. Linear FBG Temperature Sensor Interrogation with Fabry-Perot ITU Multi-wavelength Reference

    PubMed Central

    Park, Hyoung-Jun; Song, Minho

    2008-01-01

    The equidistantly spaced multi-passbands of a Fabry-Perot ITU filter are used as an efficient multi-wavelength reference for fiber Bragg grating sensor demodulation. To compensate for the nonlinear wavelength tuning effect in the FBG sensor demodulator, a polynomial fitting algorithm was applied to the temporal peaks of the wavelength-scanned ITU filter. The fitted wavelength values are assigned to the peak locations of the FBG sensor reflections, obtaining constant accuracy, regardless of the wavelength scan range and frequency. A linearity error of about 0.18% against a reference thermocouple thermometer was obtained with the suggested method.

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

    NASA Astrophysics Data System (ADS)

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

    2010-09-01

    The investigation of the presence of signals indicating possible climatic changes in progress during the second half of the last century in the coastal area of the central Tyrrhenian sea has been carried out within the context of a research programme promoted by the Italian Science Academy (alias "the Academy of the XL") and financed by the Presidential Bureau. Our goal has been a better understanding of the behaviour of the minimum and maximum temperature variations in the period 1951-1999 and the modelling of their stochastic residuals through spectral analysis and the optimized construction of suitable autoregressive one-parameter processes. The meteorological data source for this research was the Italian "Agrometeorological National DataBase" (BDAN) of the Agrometeorological Informatics National System (SIAN). The spectral and stochastic analysis of meteorological data usually require full data sets without gaps, but, in BDAN, numerous data sets taken at stations located in the investigated area were incomplete. Thus, after the selection of an adequate number of stations, both representative of the region under study and characterized by a low number of data gaps, the first step was to fill all the gaps in the daily series using specific statistical techniques. After this preliminary treatment, we were left with seven temperature series that showed enough good characteristics in order to carry out an efficient modelling. Spectral analysis of minimum and maximum temperature series permitted to identify an auto-regressive one-parameter model well representing the stochastic residual of each series. With the aid of the complete model, consisting of a deterministic component (a linear trend plus two seasonal oscillations) and a stochastic residual, one can satisfactorily reconstruct the data in the past (climatic historical analysis) and to try a prediction of future values (forecasting). Thus the proposed model appears to represent a valid method to evaluate the

  10. Long-term active layer and ground surface temperature trends: results of 12 years of observations at Alaskan CALM sites

    NASA Astrophysics Data System (ADS)

    Shiklomanov, N. I.; Nelson, F. E.; Streletskyi, D. A.; Klene, A. E.; Schimek, M.; Little, J.

    2006-12-01

    The uppermost layer of seasonal thawing above permafrost (the active layer) is an important regulator of energy and mass fluxes between the surface and the atmosphere in the polar regions. The Circumpolar Active Layer Monitoring (CALM) program is a network of sites at which data about active-layer thickness (ALT) and dynamics are collected. CALM was established in the 1990s to observe and detect the long-term response of the active layer and near-surface permafrost to changes in climate. Active layer monitoring is an important component of efforts to assess the effects of global change in permafrost environments. CALM strategies are evolving; this presentation showcases some additions to CALM observation procedures designed to monitor processes and detect changes not anticipated in the original CALM protocol of the early 1990s. In this study we used data from 12 (1995-2006) years of extensive, spatially oriented field observations at CALM sites in northern Alaska to examine landscape-specific spatial and temporal trends in active-layer thickness and air and ground surface temperature. Despite an observed increase in air temperature, active-layer thickness exhibited a decreasing trend over the study period. This result indicates that soil consolidation accompanying penetration of thaw into an ice-rich stratum at the base of the active layer has resulted in subsidence of the surface with little or no apparent thickening of the active layer, as traditionally defined. Differential Global Positioning Systems (DGPS) technology was used to detect frost heave and thaw settlement within representative landscapes. Preliminary results indicate that heave and settlement follow patterns of spatial variation similar to those of active-layer thickness. To evaluate the effect of vegetation on ground surface temperature, several heat-transfer coefficients were estimated, including land cover specific thermal diffusivity and empirical n-factors.

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

    The analysis of temperature and precipitation change and variability in high elevations is a difficult issue due to the lack of long term climatic series in those environments. Nonetheless, it is important to evaluate how much high elevations follow the same climate evolution than low lying sites. In this work, using daily data from three Andorran weather stations (maintained by the power company Forces Elèctriques d'Andorra, FEDA), climate trends of annual and seasonal temperature and precipitation were obtained for the period 1934-2008. The series are complete (99.9%) and are located in a mountainous area ranging from 1110 m to 1600 m asl. As a previous step to the analysis, data rescue, quality control and homogeneity tests were applied to the daily data. For quality control, several procedures were applied to identify and flag suspicious or erroneous data: duplicated days, outliers, excessive differences between consecutive days, flat line checking, days with maximum temperature lower that minimum temperature, and rounding analysis. All the station sites were visited to gather the available metadata. Concerning homogeneity, a homogeneous climate time series is defined as one where variations are caused only by variations in climate and not to non-climatic factors (i.e., changes in site location, instruments, station environment…). As a result, homogeneity of the series was inspected from several methodologies that have been used in a complementary and independent way in order to attain solid results: C3-SNHT (with software developed under the Spanish Government Grant CGL2007-65546-C03-02), and Caussinus-Mestre (C-M) approaches. In both cases, tests were applied to mean annual temperature and precipitation series, using Catalan and French series as references (provided respectively by the Meteorological Service of Catalonia and Météo-France, in the framework of the Action COST-ES0601: Advances in homogenisation methods of climate series: an integrated

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

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

    Sheared E × B flows are known to stabilize turbulence. This paper investigates how the linear stability of the ion-temperature-gradient (ITG) mode depends on k⊥ in both circular and MHD geometry. We study the effects of both rotation profiles of constant shear and of purely toroidal flow taken from experiment, using the global gyrokinetic particle-in-cell code NEMORB. We find that in order to effectively stabilize the linear mode, the fastest growing mode requires a shearing rate (γE) around 1-2 times its linear growth rate without flow (γ0), while both longer and shorter wavelength modes need much larger flow shear compared with their static linear growth rates. Modes with kθρi < 0.2 need γE as much as 10 times their γ0. This variation exists in both large-aspect ratio circular cross-section and small-aspect ratio MHD geometries, with both analytic constant shear and experimental flow profiles. There is an asymmetry in the suppression with respect to the sign of γE, due to competition between equilibrium profile variation and flow shear. The maximum growth rate for cases using the experimental profile in MAST equilibria occurs at shearing rates of 10% the experimental level.

  13. 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

    Bonfils, C; Duffy, P; Lobell, D

    2006-03-28

    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.

  14. Non-linear temperature variation of resistivity in graphene/silicate glass nanocomposite

    NASA Astrophysics Data System (ADS)

    Mitra, Sreemanta; Singha, Achintya; Chakravorty, Dipankar

    2013-09-01

    Graphene/glass nanocomposite was synthesized by gelation of the glass in a solution with dispersed graphene sheets. Electrical transport measurements were carried out on pellets formed by cold pressing of composite powders. Resistivity showed a nonlinear increase as a function of temperature in the range 300-400 K. This has been explained as arising due to the phonon spectra of the glass affecting the movement of electrons in graphene. Raman studies confirmed the presence of phonons in the silicate glass phase. The dielectric relaxation spectra of the composites at different temperatures are consistent with the above mechanism of the electron-glass phonon interaction.

  15. Projected changes in precipitation and temperature over the Canadian Prairie Provinces using the Generalized Linear Model statistical downscaling approach

    NASA Astrophysics Data System (ADS)

    Asong, Z. E.; Khaliq, M. N.; Wheater, H. S.

    2016-08-01

    In this study, a multisite multivariate statistical downscaling approach based on the Generalized Linear Model (GLM) framework is developed to downscale daily observations of precipitation and minimum and maximum temperatures from 120 sites located across the Canadian Prairie Provinces: Alberta, Saskatchewan and Manitoba. First, large scale atmospheric covariates from the National Center for Environmental Prediction (NCEP) Reanalysis-I, teleconnection indices, geographical site attributes, and observed precipitation and temperature records are used to calibrate GLMs for the 1971-2000 period. Then the calibrated models are used to generate daily sequences of precipitation and temperature for the 1962-2005 historical (conditioned on NCEP predictors), and future period (2006-2100) using outputs from five CMIP5 (Coupled Model Intercomparison Project Phase-5) Earth System Models corresponding to Representative Concentration Pathway (RCP): RCP2.6, RCP4.5, and RCP8.5 scenarios. The results indicate that the fitted GLMs are able to capture spatiotemporal characteristics of observed precipitation and temperature fields. According to the downscaled future climate, mean precipitation is projected to increase in summer and decrease in winter while minimum temperature is expected to warm faster than the maximum temperature. Climate extremes are projected to intensify with increased radiative forcing.

  16. On the integral-balance approach to the transient heat conduction with linearly temperature-dependent thermal diffusivity

    NASA Astrophysics Data System (ADS)

    Fabre, Antoine; Hristov, Jordan

    2016-04-01

    Closed form approximate solutions to nonlinear transient heat conduction with linearly temperature-dependent thermal diffusivity have been developed by the integral-balance integral method under transient conditions. The solutions uses improved direct approaches of the integral method and avoid the commonly used linearization by the Kirchhoff transformation. The main steps in the new solutions are improvements in the integration technique of the double-integration technique and the optimization of the exponent of the approximate parabolic profile with unspecified exponent. Solutions to Dirichlet and Neumann boundary condition problems have been developed as examples by the classical Heat-balance integral method (HBIM) and the Double-integration method (DIM). Additional examples with HBIM and DIM solutions to cases when the Kirchhoff transform is initially applied have been developed.

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

    NASA Astrophysics Data System (ADS)

    Friedland, Kevin D.; Hare, Jonathan A.

    2007-11-01

    We investigated sea surface temperature (SST) variability over large spatial and temporal scales for the continental shelf region located off the northeast coast of the United States between Cape Hatteras, North Carolina, and the Gulf of Maine using the extended reconstruction sea surface temperature (ERSST) dataset. The ERSST dataset consists of 2°×2° (latitude and longitude) monthly mean values computed from in situ data derived from the International Comprehensive Ocean Atmosphere Data Set (ICOADS). Nineteen 2°×2° bins were chosen that cover the shelf region of interest between the years of 1854 and 2005. Mean annual and range of SST were examined using dynamic factor analysis to estimate trends in both parameters, while chronological clustering was used to determine temporal SST patterns and breakpoints in the time series that are believed to signal regime shifts in SST. Both SST and SST trend analysis show that interannual variability of SST fluctuations shows strong coherence between bins, with declining SST at the beginning of the last century, followed by increasing SST through 1950, and then rapidly decreasing between 1950 and mid-1960s, with somewhat warmer SST thereafter to present. Annual SST range decreases in a seaward direction for all bins, with strong coherence for interannual variability of range fluctuations between bins. The trend in SST range shows a decreasing range at the beginning of the last century followed by an increase in range from 1920 to the late-1980s, remaining high through present with some spatial variability. A more detailed spatial analysis was conducted by grouping the data into 7 regions using principal component analysis. We analyzed regional trends in mean annual SST, seasonal SST range (summer SST-winter SST), and normalized SST minima and maxima. Both the summer and winter seasons were also analyzed using the length of each season and amplitude of the warming and cooling season, respectively, along with the spring

  18. Linear-in-temperature resistivity close to a topological metal insulator transition in ultra-multi valley fcc-ytterbium

    NASA Astrophysics Data System (ADS)

    Enderlein, Carsten; Fontes, Magda; Baggio-Saitovich, Elisa; Continentino, Mucio A.

    2016-01-01

    The semimetal-to-semiconductor transition in fcc-Yb under modest pressure can be considered a picture book example of a metal-insulator transition of the Lifshitz type. We have performed transport measurements at low temperatures in the closest vicinity of the transition and related DFT calculations of the Fermi surface. Our resistivity measurements show a linear temperature dependence with an unusually low dρ / dT at low temperatures approaching the MIT. The calculations suggest fcc-ytterbium being an ultra-multi valley system with 24 electron and 6 hole pockets in the Brillouin zone. Such Fermi surface topology naturally supports the appearance of strongly correlated phases. An estimation of the quasiparticle-enhanced effective mass shows that the scattering rate is by at least two orders of magnitude lower than in other materials which exhibit linear-in-T behavior at a quantum critical point. However, we cannot exclude an excessive effective mass enhancement, when the van Hove singularity touches the Fermi level.

  19. Proximate transition temperatures amplify linear magnetoelectric coupling in strain-disordered multiferroic BiMnO3

    NASA Astrophysics Data System (ADS)

    Mickel, Patrick R.; Jeen, Hyoungjeen; Kumar, Pradeep; Biswas, Amlan; Hebard, Arthur F.

    2016-04-01

    We report a giant linear magnetoelectric coupling in strained BiMnO3 thin films in which the disorder associated with an islanded morphology gives rise to extrinsic relaxor ferroelectricity that is not present in bulk centrosymmetric ferromagnetic crystalline BiMnO3. Strain associated with the disorder is treated as a local variable, which couples to the two ferroic order parameters, magnetization M ⃗ and polarization P ⃗. A straightforward "gas under a piston" thermodynamic treatment explains the observed correlated temperature dependencies of the product of susceptibilities and the magnetoelectric coefficient together with the enhancement of the coupling by the proximity of the ferroic transition temperatures close to the relaxor freezing temperature. Our interpretation is based on a trilinear coupling term in the free energy of the form L ⃗.(P ⃗×M ⃗) , where L ⃗ is a hidden antiferromagnetic order parameter, previously postulated by theory for BiMnO3. This phenomenological invariant not only preserves inversion and time-reversal symmetry of the strain-induced interactions but also explains the pronounced linear magnetoelectric coupling without using the more conventional higher order biquadratic interaction proportional to (P⃗.M ⃗) 2.

  20. 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)

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

    2014-03-01

    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

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

    PubMed

    Guin, Satya N; Biswas, Kanishka

    2015-04-28

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

  2. Numerical instabilities encountered in non-linear temperature analysis of radiation shield for SP-100 reactor

    NASA Astrophysics Data System (ADS)

    Barattino, William J.; El-Genk, Mohamed S.; McDaniel, Patrick J.

    The finite element method using Simplex elements and Newton-Raphson iteration has been shown to be quite accurate for solving nonlinear, nonhomogeneous, steady-state heat conduction problems, with radiative boundary conditions. However, at high values of internal heat generation, a bifurcation solution results in which the temperature at the radiative boundary oscillates between two values, neither of which is the exact solution. The introduction of a relaxation parameter in the radiative heat transfer coefficient was effective in eliminating the oscillatory behavior of the radiative surface temperature. A nodal decomposition was performed on the basic Newton-Raphson system of equations which led to a qualitative understanding of how the engineering parameters of the heat transfer-governing equation affected the oscillations. A method for determining the optimum relaxation parameter to ensure convergence and maximize the convergence rate was proposed.

  3. High temperature spin dynamics in linear magnetic chains, molecular rings, and segments by nuclear magnetic resonance

    SciTech Connect

    Adelnia, Fatemeh; Lascialfari, Alessandro; Mariani, Manuel; Ammannato, Luca; Caneschi, Andrea; Rovai, Donella; Winpenny, Richard; Timco, Grigore; Corti, Maurizio Borsa, Ferdinando

    2015-05-07

    We present the room temperature proton nuclear magnetic resonance (NMR) nuclear spin-lattice relaxation rate (NSLR) results in two 1D spin chains: the Heisenberg antiferromagnetic (AFM) Eu(hfac){sub 3}NITEt and the magnetically frustrated Gd(hfac){sub 3}NITEt. The NSLR as a function of external magnetic field can be interpreted very well in terms of high temperature spin dynamics dominated by a long time persistence of the decay of the two-spin correlation function due to the conservation of the total spin value for isotropic Heisenberg chains. The high temperature spin dynamics are also investigated in Heisenberg AFM molecular rings. In both Cr{sub 8} closed ring and in Cr{sub 7}Cd and Cr{sub 8}Zn open rings, i.e., model systems for a finite spin segment, an enhancement of the low frequency spectral density is found consistent with spin diffusion but the high cut-off frequency due to intermolecular anisotropic interactions prevents a detailed analysis of the spin diffusion regime.

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

    SciTech Connect

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

    2010-11-07

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

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

    NASA Technical Reports Server (NTRS)

    Smith, M.

    1972-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

    Smith, J. M.

    1972-01-01

    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.

  7. 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)

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

    2015-04-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

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

    PubMed

    Rost, D; Assaad, F; Blümer, N

    2013-05-01

    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

  10. Temperature effect on the build-up of exponentially growing polyelectrolyte multilayers. An exponential-to-linear transition point.

    PubMed

    Vikulina, Anna S; Anissimov, Yuri G; Singh, Prateek; Prokopović, Vladimir Z; Uhlig, Katja; Jaeger, Magnus S; von Klitzing, Regine; Duschl, Claus; Volodkin, Dmitry

    2016-03-21

    In this study, the effect of temperature on the build-up of exponentially growing polyelectrolyte multilayer films was investigated. It aims at understanding the multilayer growth mechanism as crucially important for the fabrication of tailor-made multilayer films. Model poly(L-lysine)/hyaluronic acid (PLL/HA) multilayers were assembled in the temperature range of 25-85 °C by layer-by-layer deposition using a dipping method. The film growth switches from the exponential to the linear regime at the transition point as a result of limited polymer diffusion into the film. With the increase of the build-up temperature the film growth rate is enhanced in both regimes; the position of the transition point shifts to a higher number of deposition steps confirming the diffusion-mediated growth mechanism. Not only the faster polymer diffusion into the film but also more porous/permeable film structure are responsible for faster film growth at higher preparation temperature. The latter mechanism is assumed from analysis of the film growth rate upon switching of the preparation temperature during the film growth. Interestingly, the as-prepared films are equilibrated and remain intact (no swelling or shrinking) during temperature variation in the range of 25-45 °C. The average activation energy for complexation between PLL and HA in the multilayers calculated from the Arrhenius plot has been found to be about 0.3 kJ mol(-1) for monomers of PLL. Finally, the following processes known to be dependent on temperature are discussed with respect to the multilayer growth: (i) polymer diffusion, (ii) polymer conformational changes, and (iii) inter-polymer interactions. PMID:26911320

  11. Long-term Trends in Mesospheric Temperatures at high and low latitudes derived from OH airglow spectra of Kiruna FTS and Sloan Digital Sky Survey

    NASA Astrophysics Data System (ADS)

    Kim, Yongha; Kim, Jeong-Han; Kim, Gawon; Lee, Youngsun

    2016-07-01

    We have analyzed mesospheric temperatures from OH airglow measurements with Fourier Transform Spectrometer (FTS) in the period of 2003 - 2012 at Kiruna (67.9°N, 21.1°E). We also derived mesospheric temperatures from rotational emission lines of the OH airglow (8-3) band in the sky spectra of Sloan Digital Sky Survey (SDSS) in the period of 2000 - 2014. The main objective of SDSS is to make a detailed 3-dimensional map of the universe by observing images and spectra of various celestial objects at Apache Point Observatory (APO, 32°N 105°W). From both temperature sets we first estimated the solar responses of mesospheric temperatures to F10.7 variation and the seasonal variation of mesospheric temperatures. After removing the solar response, we found the long-term mesospheric temperature trends of -4 ˜-6.6 K/decade at Kiruna and -0.02 ± 0.7 K/decade at Apache Point. Our results indicate significant cooling trend at the high latitude but very little or no cooling at the low latitude. Although both trends are comparable and consistent with other studies, the temperature trend from SDSS spectra should be regarded as unique contribution to global monitoring of climate change because the SDSS project is completely independent of climate studies.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

    Analyses of the Antarctic climate change during recent decades have demonstrated a positive continent-wide average near-surface temperature trend. Strong warming of the Antarctic Peninsula in contrast to slight cooling of the Antarctic continental interior in the last five decades has been emphasised [Turner et al. 2005]. Recently, it has been reported that significant warming of the Antarctic ice-sheet surface extends well beyond the Antarctic Peninsular to cover most of West Antarctica with a warming rate exceeding 0.1°C per decade over the past 50 years, and is strongest in winter and spring [Steig et al. 2009]. Assessments of atmospheric temperature trends have also found significant warming of the Antarctic winter troposphere. Analysing data from nine Antarctic radiosonde stations, it has been shown that regional midtropospheric temperatures have increased at a statistically significant rate of 0.5 to 0.7°C per decade over the past three decades - a major warming of the Antarctic winter troposphere that is larger than any previously identified regional tropospheric warming on Earth [Turner et al. 2006]. Analysis of climate change over the Polar Regions is particularly challenging due to the scarcity of observations from a small number of sparsely located weather stations. Obviously, data obtained by various satellite remote sensing techniques are invaluable in order to obtain spatially-complete distributions of near-surface and atmospheric temperature trends in high latitudes. For example, using the climate quality records of satellite Microwave Sounding Unit (MSU) observations, it has been shown that significant tropospheric warming prevails during Antarctic winters and springs, with the largest winter tropospheric warming of about 0.6°C per decade for 1979-2005 between 120°W and 180°W [Johanson and Fu 2007]. Recently, a new atmospheric observation technique, GPS radio occultation (RO), has been developed for acquiring the Earth's atmospheric

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

    NASA Astrophysics Data System (ADS)

    van Belle, Gerard; Pilyavsky, Gennady; von Braun, Kaspar; Ciardi, David R.; PTI Collaboration

    2016-01-01

    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 (TEFF). 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. The 58 nights of 31" observing have produced over 45,000 new photometric data points on these stars, allowing for flux and reddening determination with unprecident precision. Over the range from G5III to M8III, TEFF 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.

  15. High-temperature inert gas plasma magnetohydrodynamic energy conversion by using linear-shaped Faraday-type channel

    NASA Astrophysics Data System (ADS)

    Murakami, Tomoyuki; Zhuang, Yunqin; Okuno, Yoshihiro

    2013-02-01

    We describe high-density magnetohydrodynamic (MHD) energy conversion in a high-temperature seed-free argon plasma, for which a compact linear-shaped Faraday-type MHD electrical power generator is used. Short-time-duration single-pulse shock-tunnel-based experiments demonstrate the MHD energy conversion with varying total inflow temperature up to 9000 K and applied magnetic-flux density up to 4.0 T. The high-temperature plasma is transformed from the thermal-equilibrium state at the entrance to the weak-nonequilibrium state in the supersonic MHD channel. The discharge structure is reasonably homogeneous without suffering from serious streamer development. The power generation performance is monotonically improved by increasing total inflow temperature and strength of magnetic field. The enthalpy extraction efficiency of 13.1% and overall power density of 0.16 GW/m3 are attained. The local power density at the middle of the channel reaches 0.24 GW/m3.

  16. A Temperature-Dependent, Linearly Interpolable, Tabulated Cross Section Library Based on released ENDF/B-VII.0.

    Energy Science and Technology Software Center (ESTSC)

    2007-06-15

    Version 00 As distributed, the ENDF/B-VII.0 data includes cross sections represented in the form of a combination of resonance parameters and/or tabulated energy dependent cross sections, nominally at 0 Kelvin temperature. For use in our applications the ENDF/B-VII.0 library has been processed into cross sections at eight neutron reactor like temperatures, between 0 and 2100 Kelvin, in steps of 300 Kelvin. It has also been processed to five astrophysics like temperatures: 1, 10, 100 eV,more » 1 and 10 keV. For reference purposes, 300 Kelvin is approximately 1/40 eV, so that 1 eV is approximately 12,000 Kelvin. At each temperature the cross sections are tabulated and linearly interpolable in energy. CCC-638/TART2005 is recommended for use with these data. Codes within TART can be used to display these data or to run calculations using these data.« less

  17. A Temperature-Dependent, Linearly Interpolable, Tabulated Cross Section Library Based on ENDF/B-VII.0.

    Energy Science and Technology Software Center (ESTSC)

    2008-12-03

    Version 00 As distributed, the ENDF/B-VII.0 data includes cross sections represented in the form of a combination of resonance parameters and/or tabulated energy dependent cross sections, nominally at 0 Kelvin temperature. For use in our applications the ENDF/B-VII.0 library has been processed into cross sections at eight neutron reactor like temperatures, between 0 and 2100 Kelvin, in steps of 300 Kelvin. It has also been processed to five astrophysics like temperatures: 1, 10, 100 eV,more » 1 and 10 keV. For reference purposes, 300 Kelvin is approximately 1/40 eV, so that 1 eV is approximately 12,000 Kelvin. At each temperature the cross sections are tabulated and linearly interpolable in energy. CCC-638/TART2005 is recommended for use with these data. Codes within TART can be used to display these data or to run calculations using these data.« less

  18. Attributing surface temperature trends in the presence of natural variability: progress regarding the warming hiatus and unresolved challenges

    NASA Astrophysics Data System (ADS)

    Smoliak, B. V.; Hartmann, D. L.; Booth, J. F.

    2013-12-01

    That the observed amplitude of year-to-year climate variations are sometimes large relative to trends on time scales less than 30 years poses an ongoing challenge for detection and attribution studies, as well as the public perception of climate change. For example, despite the long term warming of the climate system, observations indicate that global average surface temperature has not risen appreciably since about 1998, when a major El Niño event occurred in the tropical Pacific. This post-1998 'warming hiatus' is well documented on the basis of global-mean, annual-mean surface temperature, but it remains poorly understood at finer spatial and temporal scales and its existence has not been unambiguously attributed to natural or anthropogenic forcings. Using observations we confirm that the warming hiatus is primarily associated with the boreal cold season. On the basis of a set of empirically-derived adjustments accounting for the influence of three known sources of natural variability, we demonstrate that the hiatus is largely a reflection of internal variability associated with spontaneously generated fluctuations of the El Nino/Southern Oscillation and extratropical atmospheric teleconnection patterns. Results are discussed in terms of their significance at spatial scales ranging from the entire globe down to the local scale, distinguishing between land and ocean and cold season and warm season.

  19. Magnetism and variable temperature and pressure crystal structures of a linear oligonuclear cobalt bis-semiquinonate.

    PubMed

    Overgaard, Jacob; Møller, Louise H; Borup, Mette A; Tricoire, Maxime; Walsh, James P S; Diehl, Marcel; Rentschler, Eva

    2016-08-01

    The crystal structure of the first oligomeric cobalt dioxolene complex, Co3(3,5-DBSQ)2((t)BuCOO)4(NEt3)2, 1, where DBSQ is 3,5-di-tert-butyl-semiquinonate, has been studied at various temperatures between 20 and 200 K. Despite cobalt-dioxolene complexes being generally known for their extensive ability to exhibit valence tautomerism (VT), we show here that the molecular geometry of compound 1 is essentially unchanged over the full temperature range, indicating the complete absence of electron transfer between ligand and metal. Magnetic susceptibility measurements clearly support the lack of VT between 8 and 300 K. The crystal structure is also determined at elevated pressures in the range from 0 to 2.5 GPa. The response of the crystal structure is surprisingly dependent on the dynamics of pressurisation: following rapid pressurization to 2 GPa, a structural phase transition occurs; yet, this is absent when the pressure is increased incrementally to 2.6 GPa. In the new high pressure phase, Z' is 2 and one of the two molecules displays changes in the coordination of one bridging carboxylate from μ2:κO:κO' to μ2:κ(2)O,O':κO', while the other molecule remains unchanged. Despite the significant changes to the molecular connectivity, analysis of the crystal structures shows that the phase transition leaves the spin and oxidation states of the molecules unaltered. Intermolecular interactions in the high pressure crystal structures have been analysed using Hirshfeld surfaces but they cannot explain the origin of the phase transition. The lack of VT in this first oligomeric Co-dioxolene complex is speculated to be due to the coordination geometry of the terminal Co-atoms, which are trigonal bipyramidally coordinated, different from the more common octahedral coordination. The energy that is gained by a hs-to-ls change in Oh is equal to Δ, while in the case of the trigonal bipyramidal (C3v), the energy gain is equal to the splitting between d(z(2)) and degenerate d

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

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    Whether 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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

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

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

    PubMed

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

    2015-04-01

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

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

    NASA Astrophysics Data System (ADS)

    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

    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.

  4. Temperature-Dependent, Linearly Interpolable, Tabulated Cross Section Library Based on ENDF/B-VI, Release 8.

    Energy Science and Technology Software Center (ESTSC)

    2005-02-21

    Version 00 As distributed, the original evaluated data include cross sections represented in the form of a combination of resonance parameters and/or tabulated energy dependent cross sections, nominally at 0 Kelvin temperature. For use in applications this library has been processed into the form of temperature dependent cross sections at eight neutron reactor like temperatures, between 0 and 2100 Kelvin, in steps of 300 Kelvin. It has also been processed to five astrophysics like temperatures,more » 1, 10, 100 eV, 1 and 10 keV. For reference purposes, 300 Kelvin is approximately 1/40 eV, so that 1 eV is approximately 12,000 Kelvin. At each temperature the cross sections are tabulated and linearly interpolable in energy. POINT2004 contains all of the evaluations in the ENDF/B-VI general purpose library, which contains evaluations for 328 materials (isotopes or naturally occurring elemental mixtures of isotopes). No special purpose ENDF/B-VI libraries, such as fission products, thermal scattering, or photon interaction data are included. The majority of these evaluations are complete, in the sense that they include all cross sections over the energy range 10-5 eV to at least 20 MeV. However, the following are only partial evaluations that either contain only single reactions and no total cross section (Mg24, K41, Ti46, Ti47, Ti48, Ti50 and Ni59), or do not include energy dependent cross sections above the resonance region (Ar40, Mo92, Mo98, Mo100, In115, Sn120, Sn122 and Sn124). The CCC-638/TART20002 code package is recommended for use with these data. Codes within TART can be used to display these data or to run calculations using these data.« less

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

    SciTech Connect

    Singh, S. K.; Awasthi, L. M.; Singh, R.; Kaw, P. K.; Jha, R.; Mattoo, S. K.

    2011-10-15

    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.

  6. Experimental Study of Sr Partitioning into Calcite at Various Linear Growth Rates and Temperatures: Preliminary Results.

    NASA Astrophysics Data System (ADS)

    Gabitov, R. I.; Watson, B. E.

    2004-05-01

    The surface of a crystal in equilibrium with surrounding fluid can have a composition that differs from the bulk crystal. If growth rate of the crystal exceeds a minimum value at which partitioning-equilibrium can be maintained, then the crystal surface composition may be "captured" by the newly-formed lattice. The degree of this entrapment increases with increasing crystal growth rate. Non-equlibrium partitioning of Sr into calcite probably occurs by this entrapment mechanism. Sr and calcite are geochemically significant in understanding the thermal history of the ocean because the substitution of Sr for Ca in calcite is temperature dependent. To improve our understanding of the partitioning of Sr into calcite, we conducted two different types of experiment: 1) calcite growth from Sr-bearing solution with analysis of the crystal cross-section by electron microprobe (bulk crystal-liquid runs); and 2) treatment of calcite cleavage surfaces with Sr-bearing solutions and examination of the top few nm surface layer by X-ray photoelectron spectroscopy (surface-liquid runs). In the series of bulk-liquid experiments crystals were grown by three different procedures: 1) precipitation on glass slide (pre-coated with calcite), where a steady flow of CaCl2 - SrCl2 and Na2CO3 solutions were mixed just before passage through a tube and allowed to drip onto a slide ("cave"-type experiments, ionic strength I=0.01); 2) growth from a CaCl2 - NH4Cl - SrCl2 solution by diffusion of CO2 from an ammonium carbonate source ("drift" experiments, I=0.52); 3) coarsening of small calcite crystals in the CaCO3-SrCO3-NaCl-H2O system at 800-950° C and 0.5-1 kb in a cold seal apparatus. The growth rate of individual crystals was determined by periodic monitoring of crystal size with time or roughly by comparison of final size with duration of the experiment. Surface-liquid experiments were performed by treatment of cleavage surfaces of natural calcite fragments in a Sr(ClO4)2 solution for 1

  7. Design of a linear synchronous motor with high temperature superconductor materials in the armature and in the field excitation system

    NASA Astrophysics Data System (ADS)

    Pina, J. M.; Neves, M. V.; McCulloch, M. D.; Rodrigues, A. L.

    2006-06-01

    The high diamagnetism observed in high temperature superconducting (HTS) materials lead to applications involving levitation such as the linear synchronous motor (LSM). Certain features taken into account in conventional LSM design cannot be applied in the HTS case, due to these materials characteristics, such as BSCCO stiffness, when used as armature windings. Also other design features, e.g. slot skewing, which reduces the space harmonics of the air gap magnetic flux density, thus influencing motor performance, plays an important role in final cost. These and other aspects such as the thrust force or the effect of motor control through an inverter are examined in this paper, where the analytical and numerical methodologies involved in the design optimisation of a LSM demonstrator with premagnetised YBCO pellets in the field excitation system and BSCCO armature windings are described. Simulation results are also included.

  8. Linear Stability Analysis of Convective Flow in a Confined Layer of Volatile Liquid Driven by a Horizontal Temperature Gradient

    NASA Astrophysics Data System (ADS)

    Grigoriev, Roman; Qin, Tongran

    2015-11-01

    Convection in layers of nonvolatile liquids with a free surface driven by a horizontal temperature gradient is a fairly well-studies problem. It is described by several nondimensional parameters: the Prandtl number Pr , the Marangoni number Ma , and the Rayleigh number Ra (or the dynamic Bond number BoD = Ra / Ma). Previous studies mostly focused on characterizing the critical Ma and the nature of the convective pattern (e.g., stationary rolls or traveling waves) as a function of Pr and BoD . To understand convection in volatile liquids one also has to consider the transport of heat and mass in the gas layer above the liquid. In confined geometries, the composition of the gas phase plays a very important role, since air tends to suppress phase change at the interface and thereby the amount of latent heat released or absorbed at the interface as a result of evaporation or condensation. Linear stability analysis of the problem based on a two-sided model shows that, for BoD = O (1) , both the critical Ma and the critical wave length of the pattern increase as the average concentration of air decreases. The predictions of linear stability analysis are found to be in good agreement with previous experimental and numerical studies of both nonvolatile and volatile fluids.

  9. A Temperature-Dependent, Linearly Interpolable, Tabulated Cross Section Library Based on ENDF/B-VI, Release 7.

    Energy Science and Technology Software Center (ESTSC)

    2001-06-13

    Version 00 As distributed, the original evaluated data include cross sections represented in the form of a combination of resonance parameters and/or tabulated energy dependent cross sections, nominally at 0 Kelvin temperature. For use in applications, these ENDF/B-VI, Release 7 data were processed into the form of temperature dependent cross sections at eight temperatures between 0 and 2100 Kelvin, in steps of 300 Kelvin. At each temperature the cross sections are tabulated and linearly interpolablemore » in energy. POINT2000 contains all of the evaluations in the ENDF/B-VI general purpose library, which contains evaluations for 324 materials (isotopes or naturally occurring elemental mixtures of isotopes). No special purpose ENDF/B-VI libraries, such as fission products, thermal scattering, photon interaction data are included. The majority of these evaluations are complete, in the sense that they include all cross sections over the energy range 10-5 eV to at least 20 MeV. However, the following are only partial evaluations that either only contain single reactions and no total cross section (Mg24, K41, Ti46, Ti47, Ti48, Ti50 and Ni59), or do not include energy dependent cross sections above the resonance region (Ar40, Mo92, Mo98, Mo100, In115, Sn120, Sn122 and Sn124). The CCC-638/TART96 code package will soon be updated to TART2000, which is recommended for use with these data. Codes within TART2000 can be used to display these data or to run calculations using these data.« less

  10. Trends in Daily and Extreme Temperature and Precipitation Indices for the Countries of the Western Indian Ocean, 1975-2008

    NASA Astrophysics Data System (ADS)

    Aguilar, Enric; Vincent, Lucie A.

    2010-05-01

    In the framework of the project "Renforcement des Capacités des Pays de la COI dans le Domaine de l'Adaptation au Changement Climatique (ACCLIMATE)" (Comission de l'Ocean Indien, COI), a workshop on homogenization of climate data and climate change indices analysis was held in Mauritius in October 2009, using the successful format prepared by the CCl/CLIVAR/JCOMM Expert Team on Climate Change Detection and Indices. Scientists from the five countries in Western Indian Ocean brought daily climatological data from their region for a meticulous assessment of the data quality and homogeneity, and for the preparation of climate change indices which can be used for analyses of changes in climate extremes. Although the period of analysis is very short, it represents a seminal step for the compilation of longer data set and allows us to examine the evolution of climate extremes in the area during the time period identified as the decades where anthropogenic warming es larger than natural forcings. This study first presents some results of the homogeneity assessment using the software package RHtestV3 (Wang and Feng 2009) which has been developed for the detection of changepoints in climatological datasets. Indices based on homogenized daily temperatures and precipitations were also prepared for the analysis of trends at more than 50 stations across the region. The results show an increase in the percentage of warm days and warm nights over 1975-2008 while changes in extreme precipitations are not as consistent.

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

    NASA Astrophysics Data System (ADS)

    Xia, X.

    2013-05-01

    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.

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

    SciTech Connect

    Samal, Pramoda Kumar; Jain, Pankaj; Saha, Rajib; Prunet, Simon; Souradeep, Tarun

    2010-05-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2007-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    meteorological trends for the Pakistan region and more broadly serves to demonstrate the utility of the presented 30 arc-second monthly precipitation and mean temperature datasets for use in data scarce regions.

  15. The temperature dependence of the crossover magnetic field of linear magnetoresistance in the Cu0.1Bi2Se3

    NASA Astrophysics Data System (ADS)

    Huang, Shiu-Ming; Yu, Shih-Hsun; Chou, Mitch

    2016-08-01

    A non-saturating linear magnetoresistance (MR) is observed in Cu0.1Bi2Se3 in a wide range of temperatures. The crossover magnetic field, B*, deviating from the linear MR, increases as the temperature increases. The experimental results show that the normalized B*, inverse MR slope and mobility follow the same temperature dependence that is consistent with the model constructed by Parich and Littlewood (PL model). The mechanism of the T 2 dependent B* is systematically and comprehensively discussed through existing theories, and might be due to the electron‑electron scattering in a highly uniform system with a few low mobility defects.

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

    PubMed

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

    2007-08-15

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

  17. Exploiting the atmosphere's memory for monthly, seasonal and interannual temperature forecasting using Scaling LInear Macroweather Model (SLIMM)

    NASA Astrophysics Data System (ADS)

    Del Rio Amador, Lenin; Lovejoy, Shaun

    2016-04-01

    Traditionally, most of the models for prediction of the atmosphere behavior in the macroweather and climate regimes follow a deterministic approach. However, modern ensemble forecasting systems using stochastic parameterizations are in fact deterministic/ stochastic hybrids that combine both elements to yield a statistical distribution of future atmospheric states. Nevertheless, the result is both highly complex (both numerically and theoretically) as well as being theoretically eclectic. In principle, it should be advantageous to exploit higher level turbulence type scaling laws. Concretely, in the case for the Global Circulation Models (GCM's), due to sensitive dependence on initial conditions, there is a deterministic predictability limit of the order of 10 days. When these models are coupled with ocean, cryosphere and other process models to make long range, climate forecasts, the high frequency "weather" is treated as a driving noise in the integration of the modelling equations. Following Hasselman, 1976, this has led to stochastic models that directly generate the noise, and model the low frequencies using systems of integer ordered linear ordinary differential equations, the most well-known are the Linear Inverse Models (LIM). For annual global scale forecasts, they are somewhat superior to the GCM's and have been presented as a benchmark for surface temperature forecasts with horizons up to decades. A key limitation for the LIM approach is that it assumes that the temperature has only short range (exponential) decorrelations. In contrast, an increasing body of evidence shows that - as with the models - the atmosphere respects a scale invariance symmetry leading to power laws with potentially enormous memories so that LIM greatly underestimates the memory of the system. In this talk we show that, due to the relatively low macroweather intermittency, the simplest scaling models - fractional Gaussian noise - can be used for making greatly improved forecasts

  18. Temperature effects on (1+1)-dimensional steady-state bright spatial solitons in biased photorefractive crystals with both the linear and quadratic effects

    NASA Astrophysics Data System (ADS)

    Hao, Lili; Wang, Qiang; Hou, Chunfeng

    2016-05-01

    The temperature effects on the intensity profile, self-deflection process, and stability of (1 + 1)-dimensional steady-state bright solitons resulting from both the linear and quadratic electro-optic effects are comprehensively analyzed. Moreover, three physical factors, i.e. diffusion effect, dark irradiance, and the dielectric constant, have been investigated through the theoretical analysis to determine which one dominates the temperature dependence of intensity profile and self-deflection of bright solitons. It is also found that the incident beam evolves into stable bright solitons in the vicinity of initial temperature, but oscillates or even collapses when the crystal temperature deviates significantly from the initial temperature.

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

    SciTech Connect

    Schnack, D. D.; Cheng, J.; Parker, S. E.; Barnes, D. C.

    2013-06-15

    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 ⊥}ρ{sub i} or ρ{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 ω=ω{sub r}+iγ. 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 δf code that assumes six-dimensional Vlasov ions and isothermal fluid electrons, as functions of k{sub ⊥}ρ{sub i} and ρ{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 ⊥}ρ{sub i} or ρ{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}/ρ{sub i}=30 and 20. The results quantify how far

  20. Spatial patterns of recent Antarctic surface temperature trends and the importance of natural variability: lessons from multiple reconstructions and the CMIP5 models

    NASA Astrophysics Data System (ADS)

    Sahai, A. K.; Borah, N.; Chattopadhyay, R.; Joseph, S.; Abhilash, S.

    2016-06-01

    The recent annually averaged warming of the Antarctic Peninsula, and of West Antarctica, stands in stark contrast to very small trends over East Antarctica. This asymmetry arises primarily from a highly significant warming of West Antarctica in austral spring and a cooling of East Antarctica in austral autumn. Here we examine whether this East-West asymmetry is a response to anthropogenic climate forcings or a manifestation of natural climate variability. We compare the observed Antarctic surface air temperature trends over two distinct time periods (1960-2005 and 1979-2005), and with those simulated by 40 models participating in Phase 5 of the Coupled Model Intercomparison Project (CMIP5). We find that the observed East-West asymmetry differs substantially between the two periods and, furthermore, that it is completely absent from the forced response seen in the CMIP5 multi-model mean, from which all natural variability is eliminated by the averaging. We also examine the relationship between the Southern Annular mode (SAM) and Antarctic temperature trends, in both models and reanalyses, and again conclude that there is little evidence of anthropogenic SAM-induced driving of the recent temperature trends. These results offer new, compelling evidence pointing to natural climate variability as a key contributor to the recent warming of West Antarctica and of the Peninsula.

  1. Regional impacts of global change: seasonal trends in extreme rainfall, run-off and temperature in two contrasting regions of Morocco

    NASA Astrophysics Data System (ADS)

    Khomsi, Kenza; Mahe, Gil; Tramblay, Yves; Sinan, Mohamed; Snoussi, Maria

    2016-05-01

    In Morocco, socio-economic activities are highly vulnerable to extreme weather events. This study investigates trends in mean and extreme rainfall, run-off and temperature, as well as their relationship with large-scale atmospheric circulation. It focuses on two Moroccan watersheds: the subhumid climate region of Bouregreg in the north and the semi-arid region of Tensift in the south, using data from 1977 to 2003. The study is based on a set of daily temperature, precipitation and run-off time series retrieved from weather stations in the two regions. Results do not show a homogeneous behaviour in the two catchments; the influence of the large-scale atmospheric circulation is different and a clear spatial dependence of the trend analysis linked to the distance from the coast and the mountains can be observed. Overall, temperature trends are mostly positive in the studied area, while weak statistically significant trends can be identified in seasonal rainfall, extreme rainfall events, average run-off and extreme run-off events.

  2. Contrails, Cirrus Trends, and Climate.

    NASA Astrophysics Data System (ADS)

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

    2004-04-01

    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 air traffic in areas where humidity is relatively constant. Surface observations from 1971 to 1995 show that cirrus increased significantly over the northern oceans and the United States while decreasing over other land areas except over western Europe where cirrus coverage was relatively constant. The surface observations are consistent with satellite-derived trends over most areas. Land cirrus trends are positively correlated with upper-tropospheric (300 hPa) humidity (UTH), derived from the National Centers for Environmental Prediction (NCEP) analyses, except over the United States and western Europe where air traffic is heaviest. Over oceans, the cirrus trends are negatively correlated with the NCEP relative humidity suggesting some large uncertainties in the maritime UTH. The NCEP UTH decreased dramatically over Europe while remaining relatively steady over the United States, thereby permitting an assessment of the cirrus contrail relationship over the United States. Seasonal cirrus changes over the United States are generally consistent with the annual cycle of contrail coverage and frequency lending additional evidence to the role of contrails in the observed trend. It is concluded that the U.S. cirrus trends are most likely due to air traffic. The cirrus increase is a factor of 1.8 greater than that expected from current estimates of linear contrail coverage suggesting that a spreading factor of the same magnitude can be used to estimate the maximum effect of the contrails. From the U.S. results and using mean contrail optical depths of 0.15 and 0.25, the maximum

  3. 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)

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

    2001-01-01

    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.

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

    SciTech Connect

    Sunyaev, Rashid A.; Khatri, Rishi E-mail: khatri@mpa-garching.mpg.de

    2013-03-01

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

  5. 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)

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

    2013-12-01

    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.

  6. 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)

    Susskind, Joel

    2008-01-01

    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.

  7. 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)

    Susskind, Joel; Molnar, Gyula

    2009-01-01

    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.

  8. The Association between Ambient Temperature and Childhood Hand, Foot, and Mouth Disease in Chengdu, China: A Distributed Lag Non-linear Analysis

    PubMed Central

    Yin, Fei; Zhang, Tao; Liu, Lei; Lv, Qiang; Li, Xiaosong

    2016-01-01

    Hand, foot and mouth disease (HFMD) has recently been recognized as a critical challenge to disease control and public health response in China. This study aimed to quantify the association between temperature and HFMD in Chengdu. Daily HFMD cases and meteorological variables in Chengdu between January 2010 and December 2013 were obtained to construct the time series. A distributed lag non-linear model was performed to investigate the temporal lagged association of daily temperature with age- and gender-specific HFMD. A total of 76,403 HFMD cases aged 0–14 years were reported in Chengdu during the study period, and a bimodal seasonal pattern was observed. The temperature-HFMD relationships were non-linear in all age and gender groups, with the first peak at 14.0–14.1 °C and the second peak at 23.1–23.2 °C. The high temperatures had acute and short-term effects and declined quickly over time, while the effects in low temperature ranges were persistent over longer lag periods. Males and children aged <1 year were more vulnerable to temperature variations. Temperature played an important role in HFMD incidence with non-linear and delayed effects. The success of HFMD intervention strategies could benefit from giving more consideration to local climatic conditions. PMID:27248051

  9. The Association between Ambient Temperature and Childhood Hand, Foot, and Mouth Disease in Chengdu, China: A Distributed Lag Non-linear Analysis.

    PubMed

    Yin, Fei; Zhang, Tao; Liu, Lei; Lv, Qiang; Li, Xiaosong

    2016-01-01

    Hand, foot and mouth disease (HFMD) has recently been recognized as a critical challenge to disease control and public health response in China. This study aimed to quantify the association between temperature and HFMD in Chengdu. Daily HFMD cases and meteorological variables in Chengdu between January 2010 and December 2013 were obtained to construct the time series. A distributed lag non-linear model was performed to investigate the temporal lagged association of daily temperature with age- and gender-specific HFMD. A total of 76,403 HFMD cases aged 0-14 years were reported in Chengdu during the study period, and a bimodal seasonal pattern was observed. The temperature-HFMD relationships were non-linear in all age and gender groups, with the first peak at 14.0-14.1 °C and the second peak at 23.1-23.2 °C. The high temperatures had acute and short-term effects and declined quickly over time, while the effects in low temperature ranges were persistent over longer lag periods. Males and children aged <1 year were more vulnerable to temperature variations. Temperature played an important role in HFMD incidence with non-linear and delayed effects. The success of HFMD intervention strategies could benefit from giving more consideration to local climatic conditions. PMID:27248051

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

    EIA Publications

    1999-01-01

    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--do not reflect the warming trend or its regional and seasonal patterns.

  11. High-precision abundances of elements in solar twin stars. Trends with stellar age and elemental condensation temperature

    NASA Astrophysics Data System (ADS)

    Nissen, P. E.

    2015-07-01

    Context. High-precision determinations of abundances of elements in the atmospheres of the Sun and solar twin stars indicate that the Sun has an unusually low ratio between refractory and volatile elements. This has led to the suggestion that the relation between abundance ratios, [X/Fe], and elemental condensation temperature, TC, can be used as a signature of the existence of terrestrial planets around a star. Aims: HARPS spectra with S/N ≳ 600 for 21 solar twin stars in the solar neighborhood and the Sun (observed via reflected light from asteroids) are used to determine very precise (σ ~ 0.01 dex) differential abundances of elements in order to see how well [X/Fe] is correlated with TC and other parameters such as stellar age. Methods: Abundances of C, O, Na, Mg, Al, Si, S, Ca, Ti, Cr, Fe, Ni, Zn, and Y are derived from equivalent widths of weak and medium-strong spectral lines using MARCS model atmospheres with parameters determined from the excitation and ionization balance of Fe lines. Non-LTE effects are considered and taken into account for some of the elements. In addition, precise (σ ≲ 0.8 Gyr) stellar ages are obtained by interpolating between Yonsei-Yale isochrones in the log g - Teff diagram. Results: It is confirmed that the ratio between refractory and volatile elements is lower in the Sun than in most of the solar twins (only one star has the same [X/Fe]-TC distribution as the Sun), but for many stars, the relation between [X/Fe] and TC is not well defined. For several elements there is an astonishingly tight correlation between [X/Fe] and stellar age with amplitudes up to ~0.20 dex over an age interval of eight Gyr in contrast to the lack of correlation between [Fe/H] and age. While [Mg/Fe] increases with age, the s-process element yttrium shows the opposite behavior meaning that [Y/Mg] can be used as a sensitive chronometer for Galactic evolution. The Na/Fe and Ni/Fe ratios are not well correlated with stellar age, but define a tight Ni

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    Objective. This study explores the statistical relations between the accumulation of heavy metals in moss and natural surface soil and potential influencing factors such as atmospheric deposition by use of multivariate regression-kriging and generalized linear models. Based on data collected in 1995, 2000, 2005 and 2010 throughout Norway the statistical correlation of a set of potential predictors (elevation, precipitation, density of different land uses, population density, physical properties of soil) with concentrations of cadmium (Cd), mercury and lead in moss and natural surface soil (response variables), respectively, were evaluated. Spatio-temporal trends were estimated by applying generalized linear models and geostatistics on spatial data covering Norway. The resulting maps were used to investigate to what extent the HM concentrations in moss and natural surface soil are correlated. Results. From a set of ten potential predictor variables the modelled atmospheric deposition showed the highest correlation with heavy metals concentrations in moss and natural surface soil. Density of various land uses in a 5 km radius reveal significant correlations with lead and cadmium concentration in moss and mercury concentration in natural surface soil. Elevation also appeared as a relevant factor for accumulation of lead and mercury in moss and cadmium in natural surface soil respectively. Precipitation was found to be a significant factor for cadmium in moss and mercury in natural surface soil. The integrated use of multivariate generalized linear models and kriging interpolation enabled creating heavy metals maps at a high level of spatial resolution. The spatial patterns of cadmium and lead concentrations in moss and natural surface soil in 1995 and 2005 are similar. The heavy metals concentrations in moss and natural surface soil are correlated significantly with high coefficients for lead, medium for cadmium and moderate for mercury. From 1995 up to 2010 the

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

    SciTech Connect

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

    2013-09-20

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

  14. Interannual Variability and Trends in Daily Temperature and Precipitation Extreme Indices in Finland in Relation to Atmospheric Circulation Patterns, 1961-2011

    NASA Astrophysics Data System (ADS)

    Irannezhad, Masoud; Kløve, Bjørn

    2016-04-01

    Daily temperature (minimum and maximum) and precipitation datasets applied at regular grid points (10×10 km2) throughout Finland for 1961-2011 were analyzed with the aim to evaluate variability and trends in weather extremes on both national and spatial scale of the country and their relationships with atmospheric circulation patterns (ACPs). Recommending by the Expert Team on Climate Change Detection and Indices (ETCCDI), the extreme indices considered for daily temperature were frost days (FD), summer days (SD) and ice days (ID); and for daily precipitation were heavy precipitation days (R10), consecutive dry days (CDD), consecutive wet days (CWD), highest 1-day precipitation amount (RX1day), simple daily intensity index (SDII) and precipitation fraction due to 95th percentile of the reference period (R95pTOT). This study used the well-known influential ACPs for Finland climate variability: North Atlantic Oscillation (NAO), Arctic Oscillation (AO), East Atlantic (EA), East Atlantic/West Russia (EA/WR), Polar (POL), Scandinavia (SCA). The non-parametric Mann-Kendall test was used to determine significant historical trends in extreme indices, and the Spearman rank correlation (rho) to identify relationships between extreme indices and ACPs. For daily temperature indices, statistically significant (p<0.05) decreasing trends were found in ID (-0.40±0.34 days/year) and FD (-0.45±0.27 days/year) on a national scale of Finland during 1961-2011. The AO and EA/WR were most significant ACPs affecting variations in ID and FD, with rho = -0.73 and 0.42, respectively. For the daily precipitation extreme indices on the nation-wide of country over the study period (1961-2011), significant trends were only determined in SDII (0.01±0.00 mm/wet days year) and R95pTOT (0.19±0.09 %/year). Both of these indices (SDII and R95pTOT) showed the strongest correlations with the EA/WR pattern, with rho between from -0.42 to -0.34. The EA/WR pattern was also the most influential ACP for

  15. The Heat Resistance of Microbial Cells Represented by D Values Can be Estimated by the Transition Temperature and the Coefficient of Linear Expansion.

    PubMed

    Nakanishi, Koichi; Kogure, Akinori; Deuchi, Keiji; Kuwana, Ritsuko; Takamatsu, Hiromu; Ito, Kiyoshi

    2015-01-01

    We previously developed a method for evaluating the heat resistance of microorganisms by measuring the transition temperature at which the coefficient of linear expansion of a cell changes. Here, we performed heat resistance measurements using a scanning probe microscope with a nano thermal analysis system. The microorganisms studied included six strains of the genus Bacillus or related genera, one strain each of the thermophilic obligate anaerobic bacterial genera Thermoanaerobacter and Moorella, two strains of heat-resistant mold, two strains of non-sporulating bacteria, and one strain of yeast. Both vegetative cells and spores were evaluated. The transition temperature at which the coefficient of linear expansion due to heating changed from a positive value to a negative value correlated strongly with the heat resistance of the microorganism as estimated from the D value. The microorganisms with greater heat resistance exhibited higher transition temperatures. There was also a strong negative correlation between the coefficient of linear expansion and heat resistance in bacteria and yeast, such that microorganisms with greater heat resistance showed lower coefficients of linear expansion. These findings suggest that our method could be useful for evaluating the heat resistance of microorganisms. PMID:26699861

  16. 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)

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

    2009-04-01

    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

  17. Recent temperature trends in the South Central Andes reconstructed from sedimentary chrysophyte stomatocysts in Laguna Escondida (1742 m a.s.l., 38°28 S, Chile)

    NASA Astrophysics Data System (ADS)

    De Jong, R.; Schneider, T.; Hernández-Almeida, I.; Grosjean, M.

    2016-02-01

    In this study we present a quantitative, high resolution reconstruction of past austral winter length in the Chilean Andes at 38°S from AD 1920 to 2009. For Laguna Escondida, a nearly pristine lake situated on the flanks of the Andes at 1740 m above sea level, past variability in the duration of the winter season (Days T4 °C) was reconstructed. Because high elevation meteorological stations are absent in this region, the reconstruction provides novel insights into recent temperature trends in the central-southern Andes. As a cold-season temperature proxy, we used chrysophyte stomatocysts. This novel proxy for cold season temperature was so far applied successfully in the European Alps and Pyrenees but has not yet been tested in the Southern Hemisphere. The reconstruction in this study was based on a newly developed Transfer Function to estimate Days T4 °C (number of consecutive days with surface water temperatures at or below 4 °C) from sedimentary stomatocyst assemblages (R2boot = 0.8, RMSEPboot = 28.7 days (= half the standard deviation)). To develop a high quality TF model, sediment traps and thermistors were placed in thirty remote lakes along an altitude gradient (420-2040 m a.s.l.). Complete materials and data were collected in 24 lakes after one year. Detailed statistical analyses indicate that modern stomatocysts primarily respond to the length of the cold season. The TF model was then applied to the sedimentary stomatocysts from a 210Pb-dated short core of L. Escondida. Comparison to independent reanalysis data showed that reconstructed changes in Days T4°C provides detailed information on winter-spring temperature variability since AD 1920. The reconstruction shows that recent warming (onset in AD 1980) in the southern Chilean Andes was not exceptional in the context of the past century. This is in strong contrast to studies from the Northern Hemisphere. The finding is also in contrast to the cooling temperature trends which were detected using

  18. Trends and variability of daily temperature extremes during 1960-2012 in the Yangtze River Basin, China

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The variability of temperature extremes has been the focus of attention during the past few decades, and may exert a great influence on the global hydrologic cycle and energy balance through thermal forcing. Based on daily minimum and maximum temperature observed by the China Meteorological Administ...

  19. Global trends

    NASA Technical Reports Server (NTRS)

    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

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  1. Performance of low-cost few-mode fiber Bragg grating sensor systems: polarization sensitivity and linearity of temperature and strain response.

    PubMed

    Ganziy, D; Rose, B; Bang, O

    2016-08-10

    We evaluate whether 850 nm fiber Bragg grating (FBG) sensor systems can use low-cost 1550 nm telecom fibers; in other words, how detrimental the influence of higher-order modes is to the polarization stability and linearity of the strain and temperature response. We do this by comparing polarization sensitivity of a few-mode 850 nm FBG sensor to a strictly single-mode 850 nm FBG sensor system using 850 nm single-mode fibers. We also compare the performance of the FBGs in strain and temperature tests. Our results show that the polarization stability and the linearity of the response degrade due to the presence of the higher-order modes. We demonstrate that, by using simple coiling of the 1550 nm fiber, one can regain the performance of the few-mode system and make it usable for high precision measurements. PMID:27534455

  2. The Short-Term Effect of Ambient Temperature on Mortality in Wuhan, China: A Time-Series Study Using a Distributed Lag Non-Linear Model

    PubMed Central

    Zhang, Yunquan; Li, Cunlu; Feng, Renjie; Zhu, Yaohui; Wu, Kai; Tan, Xiaodong; Ma, Lu

    2016-01-01

    Less evidence concerning the association between ambient temperature and mortality is available in developing countries/regions, especially inland areas of China, and few previous studies have compared the predictive ability of different temperature indictors (minimum, mean, and maximum temperature) on mortality. We assessed the effects of temperature on daily mortality from 2003 to 2010 in Jiang’an District of Wuhan, the largest city in central China. Quasi-Poisson generalized linear models combined with both non-threshold and double-threshold distributed lag non-linear models (DLNM) were used to examine the associations between different temperature indictors and cause-specific mortality. We found a U-shaped relationship between temperature and mortality in Wuhan. Double-threshold DLNM with mean temperature performed best in predicting temperature-mortality relationship. Cold effect was delayed, whereas hot effect was acute, both of which lasted for several days. For cold effects over lag 0–21 days, a 1 °C decrease in mean temperature below the cold thresholds was associated with a 2.39% (95% CI: 1.71, 3.08) increase in non-accidental mortality, 3.65% (95% CI: 2.62, 4.69) increase in cardiovascular mortality, 3.87% (95% CI: 1.57, 6.22) increase in respiratory mortality, 3.13% (95% CI: 1.88, 4.38) increase in stroke mortality, and 21.57% (95% CI: 12.59, 31.26) increase in ischemic heart disease (IHD) mortality. For hot effects over lag 0–7 days, a 1 °C increase in mean temperature above the hot thresholds was associated with a 25.18% (95% CI: 18.74, 31.96) increase in non-accidental mortality, 34.10% (95% CI: 25.63, 43.16) increase in cardiovascular mortality, 24.27% (95% CI: 7.55, 43.59) increase in respiratory mortality, 59.1% (95% CI: 41.81, 78.5) increase in stroke mortality, and 17.00% (95% CI: 7.91, 26.87) increase in IHD mortality. This study suggested that both low and high temperature were associated with increased mortality in Wuhan, and that

  3. The Short-Term Effect of Ambient Temperature on Mortality in Wuhan, China: A Time-Series Study Using a Distributed Lag Non-Linear Model.

    PubMed

    Zhang, Yunquan; Li, Cunlu; Feng, Renjie; Zhu, Yaohui; Wu, Kai; Tan, Xiaodong; Ma, Lu

    2016-01-01

    Less evidence concerning the association between ambient temperature and mortality is available in developing countries/regions, especially inland areas of China, and few previous studies have compared the predictive ability of different temperature indictors (minimum, mean, and maximum temperature) on mortality. We assessed the effects of temperature on daily mortality from 2003 to 2010 in Jiang'an District of Wuhan, the largest city in central China. Quasi-Poisson generalized linear models combined with both non-threshold and double-threshold distributed lag non-linear models (DLNM) were used to examine the associations between different temperature indictors and cause-specific mortality. We found a U-shaped relationship between temperature and mortality in Wuhan. Double-threshold DLNM with mean temperature performed best in predicting temperature-mortality relationship. Cold effect was delayed, whereas hot effect was acute, both of which lasted for several days. For cold effects over lag 0-21 days, a 1 °C decrease in mean temperature below the cold thresholds was associated with a 2.39% (95% CI: 1.71, 3.08) increase in non-accidental mortality, 3.65% (95% CI: 2.62, 4.69) increase in cardiovascular mortality, 3.87% (95% CI: 1.57, 6.22) increase in respiratory mortality, 3.13% (95% CI: 1.88, 4.38) increase in stroke mortality, and 21.57% (95% CI: 12.59, 31.26) increase in ischemic heart disease (IHD) mortality. For hot effects over lag 0-7 days, a 1 °C increase in mean temperature above the hot thresholds was associated with a 25.18% (95% CI: 18.74, 31.96) increase in non-accidental mortality, 34.10% (95% CI: 25.63, 43.16) increase in cardiovascular mortality, 24.27% (95% CI: 7.55, 43.59) increase in respiratory mortality, 59.1% (95% CI: 41.81, 78.5) increase in stroke mortality, and 17.00% (95% CI: 7.91, 26.87) increase in IHD mortality. This study suggested that both low and high temperature were associated with increased mortality in Wuhan, and that mean

  4. 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)

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

    2009-01-01

    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.

  5. Linear calculation model for prediction of color rendering index performance associated with correlated color temperature of white light-emitting diodes with two phosphors

    NASA Astrophysics Data System (ADS)

    Sun, Ching-Cherng; Chen, Ching-Yi; Chang, Jung-Hsuan; Yang, Tsung-Hsun; Ji, Wei-Shih; Jeng, Yow-Shiuan; Wu, Hsin-Mei

    2012-05-01

    Linear calculation models are proposed and demonstrated to evaluate the color rendering index (CRI) performance associated with the correlated color temperature (CCT) of a white light emitting diode with two phosphors. All the three proposed models are simple and easy, and the error in predicting the CRI is within 1, while the deviation of the CCT is around 300 K and less. Such models can be useful in evaluating the chromatic performance of a specific recipe with two phosphors.

  6. Thermal convection of temperature-dependent viscous fluids within three-dimensional faulted geothermal systems: Estimation from linear and numerical analyses

    NASA Astrophysics Data System (ADS)

    Malkovsky, Victor I.; Magri, Fabien

    2016-04-01

    Linear stability analysis and numerical simulations of density-driven flow are presented in order to estimate the effects of temperature-dependent fluid viscosity variation on the onset of free thermal convection within a three-dimensional fault embedded into impermeable rocks. The strongly coupled equations of density-driven flow are linearized. The solution was obtained through expansion into Fourier series. Simple polynomial expressions fitting the neutral stability curves are given for a range of fault aspect ratios, fluid viscosity properties, and thermal conductivity heterogeneity, providing a new tool for the estimation of critical Rayleigh numbers in faulted systems. The results are validated against the limiting case of temperature-invariant viscosity (i.e., constant). 3-D numerical simulations of free convection within a fault are run using the finite element technique in order to verify the theoretical results. It turned out that at average geothermal temperature conditions, thermal convection can develop within faults which permeability is up to 4 times lower than the case of a fluid with constant viscosity, in agreement with the developed linear theory. The polynomial expressions of this study can be applied to any numerical model for testing the feasibility of fault convection in 3-D geothermal basin.

  7. 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)

    Guan, Bin

    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

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

    NASA Astrophysics Data System (ADS)

    Pietrafesa, L. J.

    2010-12-01

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

  9. On the statistical significance of climate trends

    NASA Astrophysics Data System (ADS)

    Franzke, Christian

    2010-05-01

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

  10. Long Term Trend and 11-Year Cyclic Variations in Mesopause Temperature Data Observed by Michelson Interferometers at Arctic and Antarctic Sites

    NASA Astrophysics Data System (ADS)

    Azeem, I.; Sivjee, G. G.; Won, Y.-

    2006-05-01

    The response of the mesopause temperature to solar cycle variations has been investigated using OH airglow observations from Michelson Interferometer instruments located at Eureka (80o N, 85.56º W), Canada, Resolute Bay (74.68º N, 94.90º W), Canada, and South Pole Station, Antarctica (90o S). These aforementioned stations have been making continuous measurements of temperature and airglow emissions during the six months of each polar winter night. In this paper we present our results to elucidate solar cycle and long-term trend in the MI temperature time series data. We discuss mesospheric seasonal variation in the Northern and Southern hemispheres and compare these mesopause temperatures to highlight similarities and disagreements observed in the OH temperature response to solar cycle at Arctic and Antarctic sites. In addition, we also present He 10830Å line as a way of monitoring the response of the thermosphere to changes in solar irradiance in the EUV region over a solar cycle period.

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

    USGS Publications Warehouse

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

    2012-01-01

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

  12. Unreliability of global temperature trends: the circular logic of comparing models with models or with models inspired reconstructions to circumvent lack of validation versus actual measurements

    NASA Astrophysics Data System (ADS)

    Parker, A.; Ollier, C. D.

    2015-12-01

    This recent paper by Marotzke and Forster [1] has received media attention because it claims to have shown that the recent pause in surface temperature rise was the result of natural variability, and that climate models are not systematically overestimating the global warming. Nicholas Lewis [2] has already commented about the serious statistical errors in the paper that make the conclusion unsustainable.We note here that their supporting evidence is actually alteration of pre-selected data to sustain the global warming narrative. The "observed trends" of Marotzke and Forster are not based on the truly measured temperatures in every world gridded cell of the land and sea since the 1860s, but only on a reconstruction based on selected, scattered data that are continuously recalculated to resemble the climate model outputs.

  13. Characterizing the relationship between temperature and mortality in tropical and subtropical cities: a distributed lag non-linear model analysis in Hue, Viet Nam, 2009–2013

    PubMed Central

    Dang, Tran Ngoc; Seposo, Xerxes T.; Duc, Nguyen Huu Chau; Thang, Tran Binh; An, Do Dang; Hang, Lai Thi Minh; Long, Tran Thanh; Loan, Bui Thi Hong; Honda, Yasushi

    2016-01-01

    Background The relationship between temperature and mortality has been found to be U-, V-, or J-shaped in developed temperate countries; however, in developing tropical/subtropical cities, it remains unclear. Objectives Our goal was to investigate the relationship between temperature and mortality in Hue, a subtropical city in Viet Nam. Design We collected daily mortality data from the Vietnamese A6 mortality reporting system for 6,214 deceased persons between 2009 and 2013. A distributed lag non-linear model was used to examine the temperature effects on all-cause and cause-specific mortality by assuming negative binomial distribution for count data. We developed an objective-oriented model selection with four steps following the Akaike information criterion (AIC) rule (i.e. a smaller AIC value indicates a better model). Results High temperature-related mortality was more strongly associated with short lags, whereas low temperature-related mortality was more strongly associated with long lags. The low temperatures increased risk in all-category mortality compared to high temperatures. We observed elevated temperature-mortality risk in vulnerable groups: elderly people (high temperature effect, relative risk [RR]=1.42, 95% confidence interval [CI]=1.11–1.83; low temperature effect, RR=2.0, 95% CI=1.13–3.52), females (low temperature effect, RR=2.19, 95% CI=1.14–4.21), people with respiratory disease (high temperature effect, RR=2.45, 95% CI=0.91–6.63), and those with cardiovascular disease (high temperature effect, RR=1.6, 95% CI=1.15–2.22; low temperature effect, RR=1.99, 95% CI=0.92–4.28). Conclusions In Hue, the temperature significantly increased the risk of mortality, especially in vulnerable groups (i.e. elderly, female, people with respiratory and cardiovascular diseases). These findings may provide a foundation for developing adequate policies to address the effects of temperature on health in Hue City. PMID:26781954

  14. Evaluating CMIP5 models using GPS radio occultation COSMIC temperature in UTLS region during 2006-2013: twenty-first century projection and trends

    NASA Astrophysics Data System (ADS)

    Kishore, P.; Basha, Ghouse; Venkat Ratnam, M.; Velicogna, Isabella; Ouarda, T. B. M. J.; Narayana Rao, D.

    2016-02-01

    This paper provides a first overview of the performance of global climate models participating in the Coupled Model Inter-Comparison Project phase 5 (CMIP5) in simulating the upper troposphere and lower stratosphere (UTLS) temperatures. Temperature from CMIP5 models is evaluated with high resolution global positioning system radio occultation (GPSRO) constellation observing system for meteorology, ionosphere, and climate (COSMIC) data during the period of July 2006-December 2013. Future projections of 17 CMIP5 models based on the representative concentration pathway (RCP) 8.5 scenarios are utilized to assess model performance and to identify the biases in the temperature in the UTLS region at eight different pressure levels. The evaluations were carried out vertically, regionally, and globally to understand the temperature uncertainties in CMIP5 models. It is found that the CMIP5 models successfully reproduce the general features of temperature structure in terms of vertical, annual, and inter-annual variation. The ensemble mean of CMIP5 models compares well with the COSMIC GPSRO data with a mean difference of ±1 K. In the tropical region, temperature biases vary from one model to another. The spatial difference between COSMIC and ensemble mean reveals that at 100 hPa, the models show a bias of about ±2 K. With increase in altitude the bias decreases and turns into a cold bias over the tropical and Antarctic regions. The future projections of the CMIP5 models were presented during 2006-2099 under the RCP 8.5 scenarios. Projections show a warming trend at 300, 200, and 100 hPa levels over a wide region of 60°N-45°S. The warming decreases rapidly and becomes cooling with increase in altitudes by the end of twenty-first century. Significant cooling is observed at 30, 20, and 10 hPa levels. At 300/10 hPa, the temperature trend increases/decreases by ~0.82/0.88 K/decade at the end of twenty-first century under RCP 8.5 scenarios.

  15. Role of annealing temperatures on structure polymorphism, linear and nonlinear optical properties of nanostructure lead dioxide thin films

    NASA Astrophysics Data System (ADS)

    Zeyada, H. M.; Makhlouf, M. M.

    2016-04-01

    The powder of as synthesized lead dioxide (PbO2) has polycrystalline structure β-PbO2 phase of tetragonal crystal system. It becomes nanocrystallites α-PbO2 phase with orthorhombic crystal system upon thermal deposition to form thin films. Annealing temperatures increase nanocrystallites size from 28 to 46 nm. The optical properties of α-PbO2 phase were calculated from absolute values of transmittance and reflectance at nearly normal incidence of light by spectrophotometer measurements. The refractive and extinction indices were determined and showed a response to annealing temperatures. The absorption coefficient of α-PbO2 films is >106 cm-1 in UV region of spectra. Analysis of the absorption coefficient spectra near optical edge showed indirect allowed transition. Annealing temperature decreases the value of indirect energy gap for α-PbO2 films. The dispersion parameters such as single oscillator energy, dispersion energy, dielectric constant at high frequency and lattice dielectric constant were calculated and its variations with annealing temperatures are reported. The nonlinear refractive index (n2), third-order nonlinear susceptibility (χ(3)) and nonlinear absorption coefficient (βc) were determined. It was found that χ(3), n2 and β increase with increasing photon energy and decrease with increasing annealing temperature. The pristine film of α-PbO2 has higher values of nonlinear optical constants than for annealed films; therefore it is suitable for applications in manufacturing nonlinear optical devices.

  16. Intercomparison of CMIP5 and CMIP3 simulations of the 20th century maximum and minimum temperatures over India and detection of climatic trends

    NASA Astrophysics Data System (ADS)

    Sonali, P.; Kumar, D. Nagesh; Nanjundiah, Ravi S.

    2016-01-01

    Climate change impact assessment has become one of the most important subjects of the research community because of the recent increase in frequency of extreme events and changes in the spatiotemporal patterns of climate. This paper analyses the ability of 46 coupled climate models from Coupled Model Intercomparison Project phases 3 and 5 (CMIP5 and CMIP3). The performance of each climate model was assessed based on its skills in simulating the current seasonal cycles (monthly) of both maximum temperature and minimum temperature (Tmax, Tmin) over India. The performance measures such as coefficient of correlation (Skill_r), root mean square error (Skill_rmse), and the skill in simulating the observed probability density function (Skill_s) are mainly employed for evaluation of the simulated monthly seasonal cycle. A new metric called Skill_All which is an intersection of the above three metrics has been defined for the first time. A notable enhancement of Skill_All for CMIP5 vis-a-vis CMIP3 is observed. Further, three best CMIP5 models each for Tmax and Tmin were selected. The methodology employed in this study for model assessment is implemented for the first time for India, which establishes a robust foundation for the climate impact assessment study. The seasonal trends in Tmax and Tmin were analyzed over all the temperature homogenous regions of India for different time slots during the 20th century. Significant trends in Tmin can be seen during most of the seasons over the entire Indian region during last four decades. This establishes the signature of climate change over most parts of India.

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

    NASA Astrophysics Data System (ADS)

    Olson, M. R.; Russell, K. J.; Narayanamurti, V.; Olson, J. M.; Appelbaum, Ian

    2006-04-01

    We linearly up convert photons from 820to650nm, an energy change of ˜400meV, using a AlGaInP /GaInP quantum well heterostructure. Current and luminescence-voltage measurements are presented at temperatures from 6to300K. Photoexcited electrons are injected into the semiconductor from the Au Schottky and a forward bias across the p+-i-n heterostructure drifts electrons into the GaInP quantum well. Holes diffuse from the heavily doped substrate and radiatively recombine, emitting ˜650nm light. Linear upconversion is verified by injecting hot electrons with a solid-state tunnel junction. This device encourages other technologies, including night-vision aids and thermal energy converters.

  18. Dependences of Q-branch integrated intensity of linear-molecule pendular spectra on electric-field strength and rotational temperature and its potential applications

    PubMed Central

    Deng, Min; Wang, Hailing; Wang, Qin; Yin, Jianping

    2016-01-01

    We calculate the pendular-state spectra of cold linear molecules, and investigated the dependences of “Q-branch” integrated intensity of pendular spectra on both electric-field strength and molecular rotation-temperature. A new multi-peak structure in the “Q-branch” spectrum is appearing when the Stark interaction strength ω = μE/B equal to or larger than the critical value. Our study shows that the above results can be used not only to measure the electric-field vector and its spatial distribution in some electrostatic devices, such as the Stark decelerator, Stark velocity filter and electrostatic trap and so on, but also to survey the orientation degree of cold linear molecules in a strong electrostatic field. PMID:27231057

  19. Dependences of Q-branch integrated intensity of linear-molecule pendular spectra on electric-field strength and rotational temperature and its potential applications.

    PubMed

    Deng, Min; Wang, Hailing; Wang, Qin; Yin, Jianping

    2016-01-01

    We calculate the pendular-state spectra of cold linear molecules, and investigated the dependences of "Q-branch" integrated intensity of pendular spectra on both electric-field strength and molecular rotation-temperature. A new multi-peak structure in the "Q-branch" spectrum is appearing when the Stark interaction strength ω = μE/B equal to or larger than the critical value. Our study shows that the above results can be used not only to measure the electric-field vector and its spatial distribution in some electrostatic devices, such as the Stark decelerator, Stark velocity filter and electrostatic trap and so on, but also to survey the orientation degree of cold linear molecules in a strong electrostatic field. PMID:27231057

  20. Dependences of Q-branch integrated intensity of linear-molecule pendular spectra on electric-field strength and rotational temperature and its potential applications

    NASA Astrophysics Data System (ADS)

    Deng, Min; Wang, Hailing; Wang, Qin; Yin, Jianping

    2016-05-01

    We calculate the pendular-state spectra of cold linear molecules, and investigated the dependences of “Q-branch” integrated intensity of pendular spectra on both electric-field strength and molecular rotation-temperature. A new multi-peak structure in the “Q-branch” spectrum is appearing when the Stark interaction strength ω = μE/B equal to or larger than the critical value. Our study shows that the above results can be used not only to measure the electric-field vector and its spatial distribution in some electrostatic devices, such as the Stark decelerator, Stark velocity filter and electrostatic trap and so on, but also to survey the orientation degree of cold linear molecules in a strong electrostatic field.

  1. Seasonal trends in photosynthetic parameters and stomatal conductance of blue oak (Quercus douglasii) under prolonged summer drought and high temperature.

    PubMed

    Xu, Liukang; Baldocchi, Dennis D

    2003-09-01

    Understanding seasonal changes in photosynthetic parameters and stomatal conductance is crucial for modeling long-term carbon uptake and energy fluxes of ecosystems. Gas exchange measurements of CO2 and light response curves on blue oak leaves (Quercus douglasii H. & A.) were conducted weekly throughout the growing season to study the seasonality of photosynthetic capacity (Vcmax) and Ball-Berry slope (m) under prolonged summer drought and high temperature. A leaf photosynthetic model was used to determine Vcmax. There was a pronounced seasonal pattern in Vcmax. The maximum value of Vcmax, 127 micromol m(-2) s(-1), was reached shortly after leaf expansion in early summer, when air temperature was moderate and soil water availability was high. Thereafter, Vcmax declined as the soil water profile became depleted and the trees experienced extreme air temperatures, exceeding 40 degrees C. The decline in Vcmax was gradual in midsummer, however, despite extremely low predawn leaf water potentials (Psipd, approximately -4.0 MPa). Overall, temporal changes in Vcmax were well correlated with changes in leaf nitrogen content. During spring leaf development, high rates of leaf dark respiration (Rd, 5-6 micromol m(-2) s(-1)) were observed. Once a leaf reached maturity, Rd remained low, around 0.5 micromol m(-2) s(-1). In contrast to the strong seasonality of Vcmax, m and marginal water cost per unit carbon gain (partial partial differential E/ partial partial differential A) were relatively constant over the season, even when leaf Psipd dropped to -6.8 MPa. The constancy of partial partial differential E/ partial partial differential A suggests that stomata behaved optimally under severe water-stress conditions. We discuss the implications of our findings in the context of modeling carbon and water vapor exchange between ecosystems and the atmosphere. PMID:14532010

  2. Ground-based observations of Saturn's auroral H3+: short- and long-term trends in thermospheric temperature

    NASA Astrophysics Data System (ADS)

    O'Donoghue, J.; Melin, H.; Stallard, T.; Moore, L.

    2014-04-01

    The observations presented here used the 10-m Keck telescope situated on Mauna Kea, Hawaii. They were designed to be an integral part of the Saturn Auroral Observing Campaign of April-May 2013 (to be published in the Icarus special issue of 2014). These overlap with observations performed by the Cassini spacecraft, Hubble space telescope and the NASA infrared telescope facility (IRTF). During the observations, Saturn's sub-solar latitude was 18 degrees, i.e. Saturn was well into northern springtime/ southern autumn. In three nights of data we have found 1) the northern hemisphere is on average ~50 K cooler than the southern. This is consistent with previous work, which suggests that magnetic field strength is inversely proportional to the total heating rate. 2) the combined northern and southern temperatures range typically between 380 and 500 K on time-scales of hours/days. 3) there may be a correlation