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Sample records for linear temperature trends

  1. Linear trends in Northern Hemisphere tropospheric geopotential height and temperature patterns

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

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

  2. 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.

  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. 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.

  8. 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.

  9. Dynamic contribution to hemispheric mean temperature trends

    SciTech Connect

    Wallace, J.M.; Zhang, Y.; Renwick, J.A.

    1995-11-03

    On the basis of land station data from the Northern Hemisphere, it was determined that roughly half of the temporal variance of monthly mean hemispheric mean anomalies in surface air temperature during the period from 1900 through 1990 were linearly related to the amplitude of a distinctive spatial pattern in which the oceans are anomalously cold and the continents are anomalously warm poleward of 40 degrees north when the hemisphere is warm. Apart from an upward trend since 1975, to which El Nino has contributed, the amplitude time series associated with this pattern resembles seasonally dependent white noise. it is argued that the variability associated with this pattern is dynamically induced and is not necessarily an integral part of the fingerprint of global warming. 12 refs., 5 figs., 1 tab.

  10. Regime Changes in California Temperature Trends

    NASA Astrophysics Data System (ADS)

    Cordero, E. C.; Kessomkiat, W.; Mauget, S.

    2008-12-01

    Annual and seasonal temperature trends are analyzed for California using surface data from the US Historical Climate Network and the larger COOP network. While trends in Tmax and Tmin both show warming over the last 50 years, the temporal and spatial structure of these trends is quite different. An analysis using Mann Whitney U statistics reveals that the patterns of warming and cooling from individual stations have a distinct temporal signature that differs between Tmax and Tmin. Significant cooling trends in Tmin are found between 1920-1958, while significant warming only starts after the 1970s. In contrast, Tmax trends show a more variable pattern of warming and cooling between 1920-1980, with California wide warming only occurring after 1980. These results suggest regime changes in California temperature trends that could only occur through large scale forcing. A discussion of the various forcing mechanisms contributing to California trends and their spatial and temporal variability will be presented.

  11. Estimating linear temporal trends from aggregated environmental monitoring data

    USGS Publications Warehouse

    Erickson, Richard A.; Gray, Brian R.; Eager, Eric A.

    2017-01-01

    Trend estimates are often used as part of environmental monitoring programs. These trends inform managers (e.g., are desired species increasing or undesired species decreasing?). Data collected from environmental monitoring programs is often aggregated (i.e., averaged), which confounds sampling and process variation. State-space models allow sampling variation and process variations to be separated. We used simulated time-series to compare linear trend estimations from three state-space models, a simple linear regression model, and an auto-regressive model. We also compared the performance of these five models to estimate trends from a long term monitoring program. We specifically estimated trends for two species of fish and four species of aquatic vegetation from the Upper Mississippi River system. We found that the simple linear regression had the best performance of all the given models because it was best able to recover parameters and had consistent numerical convergence. Conversely, the simple linear regression did the worst job estimating populations in a given year. The state-space models did not estimate trends well, but estimated population sizes best when the models converged. We found that a simple linear regression performed better than more complex autoregression and state-space models when used to analyze aggregated environmental monitoring data.

  12. Trends in mean and extreme temperatures over Ibadan, Southwest Nigeria

    NASA Astrophysics Data System (ADS)

    Abatan, Abayomi A.; Osayomi, Tolulope; Akande, Samuel O.; Abiodun, Babatunde J.; Gutowski, William J.

    2017-01-01

    In recent times, Ibadan has been experiencing an increase in mean temperature which appears to be linked to anthropogenic global warming. Previous studies have indicated that the warming may be accompanied by changes in extreme events. This study examined trends in mean and extreme temperatures over Ibadan during 1971-2012 at annual and seasonal scales using the high-resolution atmospheric reanalysis from European Centre for Medium-Range Weather Forecasts (ECMWF) twentieth-century dataset (ERA-20C) at 15 grid points. Magnitudes of linear trends in mean and extreme temperatures and their statistical significance were calculated using ordinary least squares and Mann-Kendall rank statistic tests. The results show that Ibadan has witnessed an increase in annual and seasonal mean minimum temperatures. The annual mean maximum temperature exhibited a non-significant decline in most parts of Ibadan. While trends in cold extremes at annual scale show warming, trends in coldest night show greater warming than in coldest day. At the seasonal scale, we found that Ibadan experienced a mix of positive and negative trends in absolute extreme temperature indices. However, cold extremes show the largest trend magnitudes, with trends in coldest night showing the greatest warming. The results compare well with those obtained from a limited number of stations. This study should inform decision-makers and urban planners about the ongoing warming in Ibadan.

  13. Climate science: Uncertain temperature trend

    NASA Astrophysics Data System (ADS)

    Curry, Judith

    2014-02-01

    Global mean surface temperatures have not risen much over the past 15 years, despite continuing greenhouse gas emissions. An attempt to explain the warming slow-down with Arctic data gaps is only a small step towards reconciling observed and expected warming.

  14. Estimation of river and stream temperature trends under haphazard sampling

    USGS Publications Warehouse

    Gray, Brian R.; Lyubchich, Vyacheslav; Gel, Yulia R.; Rogala, James T.; Robertson, Dale M.; Wei, Xiaoqiao

    2015-01-01

    Long-term temporal trends in water temperature in rivers and streams are typically estimated under the assumption of evenly-spaced space-time measurements. However, sampling times and dates associated with historical water temperature datasets and some sampling designs may be haphazard. As a result, trends in temperature may be confounded with trends in time or space of sampling which, in turn, may yield biased trend estimators and thus unreliable conclusions. We address this concern using multilevel (hierarchical) linear models, where time effects are allowed to vary randomly by day and date effects by year. We evaluate the proposed approach by Monte Carlo simulations with imbalance, sparse data and confounding by trend in time and date of sampling. Simulation results indicate unbiased trend estimators while results from a case study of temperature data from the Illinois River, USA conform to river thermal assumptions. We also propose a new nonparametric bootstrap inference on multilevel models that allows for a relatively flexible and distribution-free quantification of uncertainties. The proposed multilevel modeling approach may be elaborated to accommodate nonlinearities within days and years when sampling times or dates typically span temperature extremes.

  15. 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.

  16. Perception of linear and nonlinear trends: using slope and curvature information to make trend discriminations.

    PubMed

    Best, Lisa A; Smith, Laurence D; Stubbs, D Alan

    2007-06-01

    This study investigated several factors influencing the perception of nonlinear relationships in time series graphs. To model real-world data, the graphed data represented different underlying trends and included different sample sizes and amounts of variability. Six trends (increasing and decreasing linear, exponential, asymptotic) were presented on four graph types (histogram, line graph, scatterplot, suspended bar graph). The experiment assessed how these factors affect trend discrimination, with the overall goal of judging what types of graphs lead to better discrimination. Six participants (two psychology professors, four psychology graduate students) viewed graphs on a computer screen and identified the underlying trend. All participants were familiar with the types of trends presented and were aware of the purpose of the experiment. Analysis indicated higher accuracy when variability was lower and sample size was higher. Choice accuracy was higher for nonlinear trends and was highest when line graphs were used.

  17. Global trends of measured surface air temperature

    NASA Technical Reports Server (NTRS)

    Hansen, James; Lebedeff, Sergej

    1987-01-01

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

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

    PubMed

    Beaubien, E G; Freeland, H J

    2000-08-01

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

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

    ERIC Educational Resources Information Center

    Bentler, Peter M.; Yuan, Ke-Hai

    1998-01-01

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

  1. Precipitation and temperature changes in eastern India by multiple trend detection methods

    NASA Astrophysics Data System (ADS)

    Sharma, Chandra Shekhar; Panda, Sudhindra N.; Pradhan, Rudra P.; Singh, Amanpreet; Kawamura, Akira

    2016-11-01

    The present study deals with spatial and temporal trend analysis of precipitation and temperature (1970-2004) in eastern India. Long-term trend direction and magnitude of change over time (annual and seasonal) were detected and analyzed by Mann-Kendall test, Sen's slope estimator, Least square linear regression, Spearman rank correlation and Sequential Mann-Kendall test. In addition to it, correlation analysis was also performed. Trend analysis of annual rainfall by different methods indicated similar annual trends in eastern India. North-eastern, south-eastern and western parts of eastern India indicated increasing trend, whereas the north-western, central and southern parts showed decreasing trend. A similar trend was observed by different methods in case of seasonal rainfall. During winter season, decreasing trend was observed in the central part, whereas similar results were obtained for pre-and post-monsoon in the western part. The trend during monsoon season was found similar to annual rainfall trend. Abrupt change in trend of rainfall with time was lacking in eastern India. Maximum temperature analysis indicated increasing trend in the western part for all the seasons (except in monsoon) and decreasing trend in the eastern part. On the contrary, increasing trend was observed in the eastern part and decreasing trend in the western half of the study area for all the seasons in case of minimum temperature. Significant changes were observed during monsoon season as compared to other seasons. A decreasing trend in mean temperature was observed in the central, southern and north western parts, whereas it was found to be increasing in the north-eastern, western and south-eastern parts. In majority of the eastern India region, any abrupt change of trend in temperatures with time was not clearly observed. Negative correlation between rainfall and maximum temperature was observed in the entire eastern India. Similar results were observed in case of minimum temperature

  2. 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.

  3. Binary Classifier Calibration Using an Ensemble of Linear Trend Estimation

    PubMed Central

    Naeini, Mahdi Pakdaman; Cooper, Gregory F.

    2017-01-01

    Learning accurate probabilistic models from data is crucial in many practical tasks in data mining. In this paper we present a new non-parametric calibration method called ensemble of linear trend estimation (ELiTE). ELiTE utilizes the recently proposed ℓ1 trend ltering signal approximation method [22] to find the mapping from uncalibrated classification scores to the calibrated probability estimates. ELiTE is designed to address the key limitations of the histogram binning-based calibration methods which are (1) the use of a piecewise constant form of the calibration mapping using bins, and (2) the assumption of independence of predicted probabilities for the instances that are located in different bins. The method post-processes the output of a binary classifier to obtain calibrated probabilities. Thus, it can be applied with many existing classification models. We demonstrate the performance of ELiTE on real datasets for commonly used binary classification models. Experimental results show that the method outperforms several common binary-classifier calibration methods. In particular, ELiTE commonly performs statistically significantly better than the other methods, and never worse. Moreover, it is able to improve the calibration power of classifiers, while retaining their discrimination power. The method is also computationally tractable for large scale datasets, as it is practically O(N log N) time, where N is the number of samples. PMID:28357158

  4. Estimating population trends with a linear model: Technical comments

    USGS Publications Warehouse

    Sauer, John R.; Link, William 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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

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

  6. Trends in Surface-Ignition Temperatures

    DTIC Science & Technology

    1944-09-01

    air ratio, and surface-ignition advance. Scope. - Tests were made on a supercharged CFR engine to deter- mine surface-ignition temperature as a...laboratory has conducted tests on a supercharged CFR engine to determine the rela- tionships between a hot-spot temperature required for surface igni...February 1, 1944. APPARATUS The tests were performed on a high-speed, supercharged CFR engine coupled to a 25-hcrsepower, alternating-ourront

  7. Wet-bulb, dew point, and air temperature trends in Spain

    NASA Astrophysics Data System (ADS)

    Moratiel, R.; Soriano, B.; Centeno, A.; Spano, D.; Snyder, R. L.

    2016-08-01

    This study analyses trends of mean (T m), maximum (T x), minimum (T n), dew point (T d), and wet-bulb temperatures (T w) on an annual, seasonal, and monthly time scale over Spain during the period 1981-2010. The main purpose was to determine how temperature and humidity changes are impacting on T w, which is probably a better measure of climate change than temperature alone. In this study, 43 weather stations were used to detect data trends using the nonparametric Mann-Kendall test and the Sen method to estimate the slope of trends. Significant linear trends observed for T m, T x, and T n versus year were 56, 58, and 47 % of the weather stations, respectively, with temperature ranges between 0.2 and 0.4 °C per decade. The months with bigger trends were April, May, June, and July with the highest trend for T x. The spatial behaviour of T d and T w was variable, with various locations showing trends from -0.6 to +0.3 °C per decade for T d and from -0.4 to +0.5 °C per decade for T w. Both T d and T w showed negative trends for July, August, September, November, and December. Comparing the trends versus time of each variable versus each of the other variables exhibited poor relationships, which means you cannot predict the trend of one variable from the trend of another variable. The trend of T x was not related to the trend of T n. The trends of T x, T m, and T n versus time were unrelated to the trends versus time of either T d or T w. The trend of T w showed a high coefficient of determination with the trend of T d with an annual value of R 2 = 0.86. Therefore, the T w trend is more related to changes in humidity than temperature.

  8. Simple circuit provides adjustable voltage with linear temperature variation

    NASA Technical Reports Server (NTRS)

    Moede, L. W.

    1964-01-01

    A bridge circuit giving an adjustable output voltage that varies linearly with temperature is formed with temperature compensating diodes in one leg. A resistor voltage divider adjusts to temperature range across the bridge. The circuit is satisfactory over the temperature range of minus 20 degrees centigrade to plus 80 degrees centigrade.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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.

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

    PubMed

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

    2012-06-29

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

  15. 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.

  16. 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.

  17. Long term trends in stratospheric temperature using NCEP/NCAR data

    NASA Astrophysics Data System (ADS)

    Fernández de Campra, Patricia; Zossi de Artigas, Marta; Valdecantos, Hector

    2016-11-01

    The stratospheric temperature trend plays an important role in distinguishing between the climate systems responses to natural and human induced changes. A linear trend of monthly mean temperature from the NCEP/NCAR reanalysis dataset for both Hemispheres with 2.5° step in latitude and longitude for the period 1979-2011, were calculated on this paper. Four different stratospheric heights: 10 hPa, 30 hPa, 50 hPa, and 70 hPa were analyzed. The observed trend pattern changes with height as expected. The area of negative trends increases when we go up in the stratosphere. Lower and middle stratosphere shows positive trends, in a section of the latitudinal band between 50° S and 60° S. As we go down the stratosphere these positive trends are smoother. At 10 hPa all trends are negative. In Southern Hemisphere at 30 hPa significant negative trends at low middle latitudes were observed. These results were compared with others, obtained by models and observations.

  18. 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.

  19. Effects of linear trends on estimation of noise in GNSS position time-series

    NASA Astrophysics Data System (ADS)

    Dmitrieva, K.; Segall, P.; Bradley, A. M.

    2017-01-01

    A thorough understanding of time-dependent noise in Global Navigation Satellite System (GNSS) position time-series is necessary for computing uncertainties in any signals found in the data. However, estimation of time-correlated noise is a challenging task and is complicated by the difficulty in separating noise from signal, the features of greatest interest in the time-series. In this paper, we investigate how linear trends affect the estimation of noise in daily GNSS position time-series. We use synthetic time-series to study the relationship between linear trends and estimates of time-correlated noise for the six most commonly cited noise models. We find that the effects of added linear trends, or conversely de-trending, vary depending on the noise model. The commonly adopted model of random walk (RW), flicker noise (FN) and white noise (WN) is the most severely affected by de-trending, with estimates of low-amplitude RW most severely biased. FN plus WN is least affected by adding or removing trends. Non-integer power-law noise estimates are also less affected by de-trending, but are very sensitive to the addition of trend when the spectral index is less than one. We derive an analytical relationship between linear trends and the estimated RW variance for the special case of pure RW noise. Overall, we find that to ascertain the correct noise model for GNSS position time-series and to estimate the correct noise parameters, it is important to have independent constraints on the actual trends in the data.

  20. Effects of linear trends on estimation of noise in GNSS position time series

    NASA Astrophysics Data System (ADS)

    Dmitrieva, K.; Segall, P.; Bradley, A. M.

    2016-10-01

    A thorough understanding of time dependent noise in Global Navigation Satellite System (GNSS) position time series is necessary for computing uncertainties in any signals found in the data. However, estimation of time-correlated noise is a challenging task and is complicated by the difficulty in separating noise from signal, the features of greatest interest in the time series. In this paper we investigate how linear trends affect the estimation of noise in daily GNSS position time series. We use synthetic time series to study the relationship between linear trends and estimates of time-correlated noise for the six most commonly cited noise models. We find that the effects of added linear trends, or conversely de-trending, vary depending on the noise model. The commonly adopted model of random walk (RW), flicker noise (FN), and white noise (WN) is the most severely affected by de-trending, with estimates of low amplitude RW most severely biased. Flicker noise plus white noise is least affected by adding or removing trends. Non-integer power-law noise estimates are also less affected by de-trending, but are very sensitive to the addition of trend when the spectral index is less than one. We derive an analytical relationship between linear trends and the estimated random walk variance for the special case of pure random walk noise. Overall, we find that to ascertain the correct noise model for GNSS position time series and to estimate the correct noise parameters, it is important to have independent constraints on the actual trends in the data.

  1. Effects of linear trends on estimation of noise in GNSS position time-series

    DOE PAGES

    Dmitrieva, K.; Segall, P.; Bradley, A. M.

    2016-10-20

    A thorough understanding of time-dependent noise in Global Navigation Satellite System (GNSS) position time-series is necessary for computing uncertainties in any signals found in the data. However, estimation of time-correlated noise is a challenging task and is complicated by the difficulty in separating noise from signal, the features of greatest interest in the time-series. In this study, we investigate how linear trends affect the estimation of noise in daily GNSS position time-series. We use synthetic time-series to study the relationship between linear trends and estimates of time-correlated noise for the six most commonly cited noise models. We find that themore » effects of added linear trends, or conversely de-trending, vary depending on the noise model. The commonly adopted model of random walk (RW), flicker noise (FN) and white noise (WN) is the most severely affected by de-trending, with estimates of low-amplitude RW most severely biased. FN plus WN is least affected by adding or removing trends. Non-integer power-law noise estimates are also less affected by de-trending, but are very sensitive to the addition of trend when the spectral index is less than one. We derive an analytical relationship between linear trends and the estimated RW variance for the special case of pure RW noise. Finally, overall, we find that to ascertain the correct noise model for GNSS position time-series and to estimate the correct noise parameters, it is important to have independent constraints on the actual trends in the data.« less

  2. Effects of linear trends on estimation of noise in GNSS position time-series

    SciTech Connect

    Dmitrieva, K.; Segall, P.; Bradley, A. M.

    2016-10-20

    A thorough understanding of time-dependent noise in Global Navigation Satellite System (GNSS) position time-series is necessary for computing uncertainties in any signals found in the data. However, estimation of time-correlated noise is a challenging task and is complicated by the difficulty in separating noise from signal, the features of greatest interest in the time-series. In this study, we investigate how linear trends affect the estimation of noise in daily GNSS position time-series. We use synthetic time-series to study the relationship between linear trends and estimates of time-correlated noise for the six most commonly cited noise models. We find that the effects of added linear trends, or conversely de-trending, vary depending on the noise model. The commonly adopted model of random walk (RW), flicker noise (FN) and white noise (WN) is the most severely affected by de-trending, with estimates of low-amplitude RW most severely biased. FN plus WN is least affected by adding or removing trends. Non-integer power-law noise estimates are also less affected by de-trending, but are very sensitive to the addition of trend when the spectral index is less than one. We derive an analytical relationship between linear trends and the estimated RW variance for the special case of pure RW noise. Finally, overall, we find that to ascertain the correct noise model for GNSS position time-series and to estimate the correct noise parameters, it is important to have independent constraints on the actual trends in the data.

  3. 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.

  4. Detection of temperature trends within the course of the year using "shifting subseasons"

    NASA Astrophysics Data System (ADS)

    Cahynova, Monika; Pokorna, Lucie

    2015-04-01

    Recent global warming has not been ubiquitous - there are seasons, regions, and time periods with clearly discernible zero or downward air temperature trends. Regions that are not warming or are even cooling - also known as "warming holes" - have been previously detected mainly in autumn in the second half of the 20th century in large parts of North America as well as in Central and Eastern Europe. Daily maximum and minimum temperature (TX and TN, respectively) and daily temperature range (DTR) at 136 stations in Europe during the period 1961-2000 are employed to precisely locate the seasonal and subseasonal trends within the course of the year. Linear trends are calculated for moving "subseasons" of differing lengths (10, 20, 30, 60, and 90 days), each shifted by one day. Cluster analysis of the annual course of "shifting trends" reveals relatively well-defined regions with similar trend behavior. Over most of Europe, the observed warming is greatest in winter, and the highest trend magnitudes are reached by TN in Eastern Europe. Two regions stand out: in Iceland and the Eastern Mediterranean, the trends during the year are weak, positive in summer and mostly negative in winter, reaching statistical significance at only few stations. Significant autumn cooling centered on mid-November was found in Eastern and Southeastern Europe for both TX and TN; in many other regions trends are close to zero in the same period. Other clearly non-warming (or even cooling) periods occur in Western and Central Europe in February, April, and late June. Trends of DTR are largely inconclusive and no general picture can be drawn. Our results suggest that using different time scales, apart from the conventional three-month seasons or common months, is highly desirable for a proper location of trends within the course of the year.

  5. 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

  6. Long-term dynamics of OH * temperatures over central Europe: trends and solar correlations

    NASA Astrophysics Data System (ADS)

    Kalicinsky, Christoph; Knieling, Peter; Koppmann, Ralf; Offermann, Dirk; Steinbrecht, Wolfgang; Wintel, Johannes

    2016-12-01

    We present the analysis of annual average OH* temperatures in the mesopause region derived from measurements of the Ground-based Infrared P-branch Spectrometer (GRIPS) at Wuppertal (51° N, 7° E) in the time interval 1988 to 2015. The new study uses a temperature time series which is 7 years longer than that used for the latest analysis regarding the long-term dynamics. This additional observation time leads to a change in characterisation of the observed long-term dynamics. We perform a multiple linear regression using the solar radio flux F10.7 cm (11-year cycle of solar activity) and time to describe the temperature evolution. The analysis leads to a linear trend of (-0.089 ± 0.055) K year-1 and a sensitivity to the solar activity of (4.2 ± 0.9) K (100 SFU)-1 (r2 of fit 0.6). However, one linear trend in combination with the 11-year solar cycle is not sufficient to explain all observed long-term dynamics. In fact, we find a clear trend break in the temperature time series in the middle of 2008. Before this break point there is an explicit negative linear trend of (-0.24 ± 0.07) K year-1, and after 2008 the linear trend turns positive with a value of (0.64 ± 0.33) K year-1. This apparent trend break can also be described using a long periodic oscillation. One possibility is to use the 22-year solar cycle that describes the reversal of the solar magnetic field (Hale cycle). A multiple linear regression using the solar radio flux and the solar polar magnetic field as parameters leads to the regression coefficients Csolar = (5.0 ± 0.7) K (100 SFU)-1 and Chale = (1.8 ± 0.5) K (100 µT)-1 (r2 = 0.71). The second way of describing the OH* temperature time series is to use the solar radio flux and an oscillation. A least-square fit leads to a sensitivity to the solar activity of (4.1 ± 0.8) K (100 SFU)-1, a period P = (24.8 ± 3.3) years, and an amplitude Csin = (1.95 ± 0.44) K of the oscillation (r2 = 0.78). The most important finding here is that using this

  7. 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

  8. Stratospheric Temperature Trends from Small Rockets Between 1969-1995

    NASA Technical Reports Server (NTRS)

    Schmidlin, F. J.

    2000-01-01

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

  9. Recent trends of extreme temperature indices for the Iberian Peninsula

    NASA Astrophysics Data System (ADS)

    Fonseca, D.; Carvalho, M. J.; Marta-Almeida, M.; Melo-Gonçalves, P.; Rocha, A.

    2016-08-01

    Climate change and extreme climate events have a significant impact on societies and ecosystems. As a result, climate change projections, especially related with extreme temperature events, have gained increasing importance due to their impacts on the well-being of the population and ecosystems. However, most studies in the field are based on coarse global climate models (GCMs). In this study, we perform a high resolution downscaling simulation to evaluate recent trends of extreme temperature indices. The model used was Weather Research and Forecast (WRF) forced by MPI-ESM-LR, which has been shown to be one of the more robust models to simulate European climate. The domain used in the simulations includes the Iberian Peninsula and the simulation covers the 1986-2005 period (i.e. recent past). In order to study extreme temperature events, trends were computed using the Theil-Sen method for a set of temperature indexes defined by the Expert Team on Climate Change Detection and Indices (ETCCDI). For this, daily values of minimum and maximum temperatures were used. The trends of the indexes were computed for annual and seasonal values and the Mann-Kendall Trend test was used to evaluate their statistical significance. In order to validate the results, a second simulation, in which WRF was forced by ERA-Interim, was performed. The results suggest an increase in the number of warm days and warm nights, especially during summer and negative trends for cold nights and cold days for the summer and spring. For the winter, contrary to the expected, the results suggest an increase in cold days and cold nights (warming hiatus). This behavior is supported by the WRF simulation forced by ERA-Interim for the autumn days, pointing to an extension of the warming hiatus phenomenon to the remaining seasons. These results should be used with caution since the period used to calculate the trends may not be long enough for this purpose. However, the general sign of trends are similar for

  10. Temperature trends in regions affected by increasing aridity/humidity

    NASA Astrophysics Data System (ADS)

    Jones, Philip D.; Reid, Phillip A.

    A paper in 1991 claimed that regions affected by desertification experience warming trends relative to neighbouring areas. To assess this, an index of aridity/humidity based on the ratio of annual precipitation to annual potential evapotranspiration totals (P/PET) is developed. This index is used to define regions experiencing increases (and those where the increase is statistically significant) in aridity and humidity. We also consider regions always arid (average values of P/PET <0.5) and always humid (P/PET >2.0). Trends of average annual and summer surface air temperature are then calculated for regions in the various aridity/humidity categories and compared to most of the rest of the world's land areas equatorward of 60°. The results indicate that most of the differences in trends between categories are not statistically significant.

  11. 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.

  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. 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.

  14. 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.

  15. 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.

  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 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.

  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.

  20. Precise monitoring of global temperature trends from satellites

    NASA Technical Reports Server (NTRS)

    Spencer, Roy W.; Christy, John R.

    1990-01-01

    Passive microwave radiometry from satellites provides more precise atmospheric temperature information than that obtained from the relatively sparse distribution of thermometers over the earth's surface. Accurate global atmospheric temperature estimates are needed for detection of possible greenhouse warming, evaluation of computer models of climate change, and for understanding important factors in the climate system. Analysis of the first 10 years (1979 to 1988) of satellite measurements of lower atmospheric temperature changes reveals a monthly precision of 0.01 C, large temperature variability on time scales from weeks to several years, but no obvious trend for the 10-year period. The warmest years, in descending order, were 1987, 1988, 1983, and 1980. The years 1984, 1985, and 1986 were the coolest.

  1. 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.

  2. 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.

  3. Apply a hydrological model to estimate local temperature trends

    NASA Astrophysics Data System (ADS)

    Igarashi, Masao; Shinozawa, Tatsuya

    2014-03-01

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

  4. 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.

  5. Temperature trends during the Present and Last interglacial periods - A multi-model-data comparison

    NASA Astrophysics Data System (ADS)

    Bakker, Pepijn; Masson-Delmotte, Valérie; Martrat, Belen; Charbit, Sylvie; Renssen, Hans

    2013-04-01

    We present the first multi-model-data comparison of transient millennial-scale temperature changes through the Present and Last interglacial periods (PIG and LIG respectively). Though primarily driven by insolation changes associated with well-known variations in Earth's orbital parameters, the response of the climate system 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 climate trends and to help in understanding the recorded climatic signal and the underlying climate dynamics. During the last decade, substantial progress has been made by documenting past climate variability from new archives with improved chronologies for the PIG and LIG periods. In parallel, the increased computing capacities as well as the development of computationally efficient climate models have enabled transient multi-millennial climate simulations. This allows us to compare PIG and LIG multi-millennial temperature trends derived from transient climate experiments (9 different climate models) with alkenone-based temperature reconstructions (117 locations globally distributed; about 45% of them with the LIG interval) and ice-core-based temperature profiles from Greenland and Antarctica (12 sites; 6 include the LIG). Our analysis shows that in Greenland and Antarctica the multi-model-mean temperature trends for the warmest months compare well with ice-core based temperature reconstructions. Regarding reconstructed annual mean temperatures based on alkenone-data, models and data are in reasonable agreement with some exceptions at high-latitude areas. The next step in the analysis is to assess whether the simulated warmest month temperature trends of the PIG and LIG periods are linearly scaled to the orbital forcing. In the Northern Hemisphere the models consistently show a linear response to the trends in the insolation

  6. 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.

  7. Trends in rainy season characteristics and temperature extremes over Mexico

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

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

  8. Multi-decadal surface temperature trends in East Antarctica inferred from borehole firn temperature measurements and geophysical inverse methods

    NASA Astrophysics Data System (ADS)

    Muto, Atsuhiro

    The climate trend of the Antarctic interior remains unclear relative to the rest of the globe because of a lack of long-term weather records. Recent studies by other authors utilizing sparse available records, satellite data, and models have estimated a significant warming trend in the near-surface air temperature in West Antarctica and weak and poorly constrained warming trend in East Antarctica for the past 50 years. In this dissertation, firn thermal profiling was used to detect multi-decadal surface temperature trends in the interior of East Antarctica where few previous records of any kind exist. The surface temperature inversion from firn temperature profiles provides a climate reconstruction independent of firn chemistry, sparse weather data, satellite data, or ice cores, and therefore may be used in conjunction with these data sources for corroboration of climate trends over the large ice sheets. During the Norwegian-U.S. IPY Scientific Traverse of East Antarctica, in the austral summers of 2007--08 and 2008--09, thermal-profiling telemetry units were installed at five locations. Each unit consists of 16 PRTs (Platinum Resistance Thermometers) distributed in a back-filled borehole of 80 to 90 m deep. The accuracy of the temperature measurement is 0.03 K. Geophysical inverse methods (linearized and Monte Carlo inversion) were applied to one full year of data collected from three units installed near the ice divide in the Dome Fuji/Pole of Inaccessibility region and one on Recovery Lake B, situated >500 km south to south-west of and >1000 m lower in altitude than sites near the ice divide. Three sites near the ice divide indicate that the mean surface temperatures have increased approximately 1 to 1.5 K within the past ˜50 years although the onset and the duration of this warming vary by site. On the other hand, slight cooling to no change was detected at the Recovery Lake B site. Although uncertainties remain due to limitations of the method, these results

  9. 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.

  10. 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.

  11. 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.

  12. 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).

  13. The Long Term Trend and Solar Cycle Variation Observed in 12 Years of Hydroxyl Temperatures Over Davis, Antarctica.

    NASA Astrophysics Data System (ADS)

    French, J.; Burns, G.

    2007-05-01

    Hydroxyl (6-2)-band rotational temperature observations have been accumulated at Davis station, Antarctica (68°S, 78°E) over 12 consecutive years since 1995. Hydroxyl emissions originate in a layer ~8km thick near 87km altitude and the rotational temperatures derived are a proxy for atmospheric temperature near the mesopause. This region is modelled to be sensitive to increases in CO2and is expected to cool over the long term as the increased CO2radiates more absorbed energy to space. Here we examine the seasonal and inter-year variability in hydroxyl temperatures and use a multiple linear regression analysis to extract solar cycle and long term linear trend coefficients. A total of 3413 nightly average temperatures are calculated from over 150,000 individual temperature measurements that pass selection criteria over the 12 year interval. Winter average temperatures, calculated from the nightly averages between day 108 to 258 each year vary between 203 and 210K and show a solar cycle dependence of about 0.05 K/solar flux unit (or 6K per solar cycle). The long term linear trend in these data (-0.11±0.12 K/year) is not statistically different from zero, in contrast to some published trends of up to -0.7 K/year. The winter of 2002 was anomalously warm before the unusual southern hemisphere strat-warm and early ozone hole break-up. Including this year has a considerable effect on the trend coefficients and our estimate of the number of years required to detect a statistically significant trend.

  14. Trends in upper stratospheric temperatures as observed by rocketsondes (1965-1983)

    NASA Technical Reports Server (NTRS)

    Johnson, K. W.; Gelman, M. E.

    1985-01-01

    Recent interest in possible anthropogenically induced changes in stratospheric ozone has led to a number of modeling studies. These studies indicate that stratospheric temperature changes would be related to stratospheric ozone changes. Therefore, this study was motivated by a concern to find out whether or not any significant trend in upper stratospheric temperatures could be ascertained from available observational data. June monthly mean values for 40 to 45 km layer were calculated for all Western Hemisphere rocketsonde stations for which data was available. Mean temperatures for each June were then used to calculate linear least squares regression coefficients with latitude of the stations as the independent variable. The resulting coefficients were used to calculate area-weighted mean temperatures for 25 deg N to 55 deg N. A two-to-three degree temperature drop in the early 1970s is indicated. It was noted, however, that this temperature decline coincides with a change in the principal observing system from the Arcasconde system to the Datasonde system. In order to study this temperature decrease more closely, similar mean temperatures were calculated for the 25 to 30 km layer using both rocketsondes and support radiosondes.

  15. Atmospheric controls on northeast Pacific temperature trends and variations, 1900-2012

    NASA Astrophysics Data System (ADS)

    Mantua, N. J.; Johnstone, J. A.

    2014-12-01

    Over the past century, northeast Pacific coastal sea surface temperatures (SSTs) and land-based surface air temperatures (SATs) display multidecadal variations associated with the Pacific Decadal Oscillation, in addition to a warming trend of ~0.5 to 1°C. Using independent records of sea-level pressure (SLP), SST and SAT, this study investigates NE Pacific coupled atmosphere-ocean variability from 1900 to 2012, with emphasis on the coastal areas around North America. We use a linear stochastic time series model to show that the SST evolution around the NE Pacific coast can be explained by a combination of regional atmospheric forcing and ocean persistence, accounting for 63% of nonseasonal monthly SST variance (r = 0.79) and 73% of variance in annual means (r = 0.86). We show that SLP reductions and related atmospheric forcing led to century-long warming around the NE Pacific margins, with strongest trends observed from 1910-20 to 1940. NE Pacific circulation changes are estimated to account for more than 80% of the 1900-2012 linear warming in coastal NE Pacific SST and US Pacific northwest (Washington, Oregon and northern California) SAT. An ensemble of climate model simulations run under the same historical radiative forcings fails to reproduce the observed regional circulation trends. These results suggest that natural, internally-generated changes in atmospheric circulation were the primary cause of coastal NE Pacific warming from 1900 to 2012, and demonstrate more generally that regional mechanisms of interannual and multidecadal temperature variability can also extend to century time scales.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. Are recent global mean temperature trends anomalous relative to the CMIP5 ensemble?

    NASA Astrophysics Data System (ADS)

    Lin, M.; Huybers, P. J.

    2015-12-01

    Recent studies have described a slow-down in the rise in global mean temperature over the past 15 years, noting that these trends are anomalous with respect to the trends predicted by the CMIP5 ensemble. This result has been shown to be sensitive to the choice of starting year when assessing the hiatus with a simple linear regression. It is also sensitive to assumptions about the independence of CMIP5 ensemble members when estimating distributions of the CMIP5 ensemble. We address these interdependences of ensemble members by exploring two end-member scenarios of the CMIP5 ensemble: one in which each ensemble member is assumed independent and a second in which modeling centers are assumed independent. A more stable metric of trend, the δ-slope, is employed to measure the recent divergence of a temperature time-series from the average CMIP5 projection. When treating each CMIP5 ensemble member as independent, we find that observed recent trends are anomalous for all hiatus periods starting after 1997 at the 95% confidence level. However, for the scenario assuming modeling centers to be independent, we find that observed recent trends are consistent with the CMIP5 ensemble at the 95% confidence level. This result holds across all plausible hiatus starting years tested (1990-2005). Using the Ansari-Bradley rank-sum test, seven modeling centers comprising 58 ensemble members are each shown to have lower spread in δ-slope values than the distribution of δ slope values of CMIP5 ensemble members outside each modeling center at the 95% confidence level. This supports the end-member scenario that treats each modeling center as independent. In addition, examination of spatial patterns of δ-slope in each CMIP5 ensemble member reveals that the simulation that is closest to observations in global mean temperature δ-slope value also has one of the highest δ-slope spatial pattern correlations with observations. This pattern reflects a strong negative phase of the Pacific

  2. 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

  3. Future trend in seasonal lengths and extreme temperature distributions over South Korea

    NASA Astrophysics Data System (ADS)

    Lee, Jangho

    2017-02-01

    CSEOF analysis is conducted on the daily mean, maximum, and minimum temperatures measured at 60 Korea Meteorological Administration stations in the period of 1979-2014. Each PC time series is detrended and fitted to an autoregressive (AR) model. The resulting AR models are used to generate 100 sets of synthetic PC time series for the period of 1979-2064, and the linear trends are added back to the resulting PC time series. Then, 100 sets of synthetic daily temperatures are produced by using the synthetic PC time series together with the The cyclostationary EOF (CSEOF) loading vectors. The statistics of the synthetic daily temperatures are similar to those of the original data during the observational period (1979-2064). Based on the synthetic datasets, future statistics including distribution of extreme temperatures and the length of four seasons have been analyzed. Average daily temperature in spring is expected to decrease by a small amount, whereas average temperatures in summer, fall and winter are expected to increase. Standard deviation of daily temperatures is expected to increase in all four seasons. The Generalized Extreme Value and Generalized Pareto distributions of extreme temperatures indicate that both warm and cold extremes are likely to increase in summer, while only warm extremes are predicted to increase significantly in winter. Thus, heat waves will increase and cold waves will decrease in number in future. Spring and fall will be shorter, whereas summer and winter will be longer. A statistical prediction carried out in the present study may serve as a baseline solution for numerical predictions using complex models.

  4. 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.

  5. 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.; 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.

  6. Interdecadal variability and linear trend of sea level along the Japanese coast

    NASA Astrophysics Data System (ADS)

    Yasuda, T.; Sueyoshi, M.

    2010-12-01

    Interdecadal variability and linear trend of sea level along the Japanese coast during the 20th century and their causes are investigated using tide gauge, altimeter, and ocean heat content data. We also examine those in the future climate projected by IPCC-AR4 CGCMs. Historical tide gauge data show that sea level along the Japanese coast has no significant trend during the 20th century. Rather, bidecadal variability and simultaneous variation along the Japanese coast are remarkable. In order to examine the causes of this sea level variability, OGCM experiments forced by the historical atmospheric reanalysis data have been conducted. The long-term variability of the sea level along the Japanese coast is mainly due to the baroclinic Rossby waves forced by changes in the large-scale wind stress fields in the North Pacific with a lag of several years. The bidecadal variability is caused primarily by the meridional shift of the boundary between the subtropical and subpolar gyres, which is forced by the shifting of the westerlies over the central North Pacific. Sea level along the Japanese coast has risen significantly since the mid-1980s. Although this is partly explained by the dynamical response to the wind stress fields, it can be considered that the global mean thermal expansion contributes considerably. On the sea level rise along the Japanese coast in the future climate, multi-model ensemble means indicate sea level change associated with the northward shift of the Kuroshio Extension. 18cm change in the east of Japan is comparable to global mean steric sea level rise. It remains large uncertainty in the atmospheric change over the midlatitude North Pacific associated with global warming. Therefore, it is important to reduce its uncertainty, in addition to evaluate other contributions such as ice sheet melting.

  7. 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.

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

    NASA Astrophysics Data System (ADS)

    Zheng, Luhai; Jin, Jianxun

    2011-08-01

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

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

    PubMed

    Hossain, Murshed

    2014-07-08

    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

  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. 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.

  14. Influences of removing linear and nonlinear trends from climatic variables on temporal variations of annual reference crop evapotranspiration in Xinjiang, China.

    PubMed

    Li, Yi; Yao, Ning; Chau, Henry Wai

    2017-08-15

    Reference crop evapotranspiration (ETo) is a key parameter in field irrigation scheduling, drought assessment and climate change research. ETo uses key prescribed (or fixed or reference) land surface parameters for crops. The linear and nonlinear trends in different climatic variables (CVs) affect ETo change. This research aims to reveal how ETo responds after the related CVs were linearly and nonlinearly detrended over 1961-2013 in Xinjiang, China. The ETo-related CVs included minimum (Tmin), average (Tave), and maximum air temperatures (Tmax), wind speed at 2m (U2), relative humidity (RH) and sunshine hour (n). ETo was calculated using the Penman-Monteith equation. A total of 29 ETo scenarios, including the original scenario, 14 scenarios in Group I (ETo was recalculated after removing linear trends from single or more CVs) and 14 scenarios in Group II (ETo was recalculated after removing nonlinear trends from the CVs), were generated. The influence of U2 was stronger than influences of the other CVs on ETo for both Groups I and II either in northern, southern or the entirety of Xinjiang. The weak influences of increased Tmin, Tave and Tmax on increasing ETo were masked by the strong effects of decreased U2 &n and increased RH on decreasing ETo. The effects of the trends in CVs, especially U2, on changing ETo were clearly shown. Without the general decreases of U2, ETo would have increased in the past 53years. Due to the non-monotone variations of the CVs and ETo, the results of nonlinearly detrending CVs on changing ETo in Group II should be more plausible than the results of linearly detrending CVs in Group I. The decreasing ETo led to a general relief in drought, which was indicated by the recalculated aridity index. Therefore, there would be a slightly lower risk of water utilization in Xinjiang, China.

  15. 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...

  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. 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.

  18. 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.

  19. Kernel reconstruction methods for Doppler broadening - Temperature interpolation by linear combination of reference cross sections at optimally chosen temperatures

    NASA Astrophysics Data System (ADS)

    Ducru, Pablo; Josey, Colin; Dibert, Karia; Sobes, Vladimir; Forget, Benoit; Smith, Kord

    2017-04-01

    This article establishes a new family of methods to perform temperature interpolation of nuclear interactions cross sections, reaction rates, or cross sections times the energy. One of these quantities at temperature T is approximated as a linear combination of quantities at reference temperatures (Tj). The problem is formalized in a cross section independent fashion by considering the kernels of the different operators that convert cross section related quantities from a temperature T0 to a higher temperature T - namely the Doppler broadening operation. Doppler broadening interpolation of nuclear cross sections is thus here performed by reconstructing the kernel of the operation at a given temperature T by means of linear combination of kernels at reference temperatures (Tj). The choice of the L2 metric yields optimal linear interpolation coefficients in the form of the solutions of a linear algebraic system inversion. The optimization of the choice of reference temperatures (Tj) is then undertaken so as to best reconstruct, in the L∞ sense, the kernels over a given temperature range [Tmin ,Tmax ]. The performance of these kernel reconstruction methods is then assessed in light of previous temperature interpolation methods by testing them upon isotope 238U. Temperature-optimized free Doppler kernel reconstruction significantly outperforms all previous interpolation-based methods, achieving 0.1% relative error on temperature interpolation of 238U total cross section over the temperature range [ 300 K , 3000 K ] with only 9 reference temperatures.

  20. Kernel reconstruction methods for Doppler broadening — Temperature interpolation by linear combination of reference cross sections at optimally chosen temperatures

    DOE PAGES

    Ducru, Pablo; Josey, Colin; Dibert, Karia; ...

    2017-01-25

    This paper establishes a new family of methods to perform temperature interpolation of nuclear interactions cross sections, reaction rates, or cross sections times the energy. One of these quantities at temperature T is approximated as a linear combination of quantities at reference temperatures (Tj). The problem is formalized in a cross section independent fashion by considering the kernels of the different operators that convert cross section related quantities from a temperature T0 to a higher temperature T — namely the Doppler broadening operation. Doppler broadening interpolation of nuclear cross sections is thus here performed by reconstructing the kernel of themore » operation at a given temperature T by means of linear combination of kernels at reference temperatures (Tj). The choice of the L2 metric yields optimal linear interpolation coefficients in the form of the solutions of a linear algebraic system inversion. The optimization of the choice of reference temperatures (Tj) is then undertaken so as to best reconstruct, in the L∞ sense, the kernels over a given temperature range [Tmin,Tmax]. The performance of these kernel reconstruction methods is then assessed in light of previous temperature interpolation methods by testing them upon isotope 238U. Temperature-optimized free Doppler kernel reconstruction significantly outperforms all previous interpolation-based methods, achieving 0.1% relative error on temperature interpolation of 238U total cross section over the temperature range [300 K,3000 K] with only 9 reference temperatures.« less

  1. 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.

  2. 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.

  3. 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.

  4. On the statistical significance of surface air temperature trends in the Eurasian Arctic region

    NASA Astrophysics Data System (ADS)

    Franzke, C.

    2012-12-01

    This study investigates the statistical significance of the trends of station temperature time series from the European Climate Assessment & Data archive poleward of 60°N. The trends are identified by different methods and their significance is assessed by three different null models of climate noise. All stations show a warming trend but only 17 out of the 109 considered stations have trends which cannot be explained as arising from intrinsic climate fluctuations when tested against any of the three null models. Out of those 17, only one station exhibits a warming trend which is significant against all three null models. The stations with significant warming trends are located mainly in Scandinavia and Iceland.

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

    USGS Publications Warehouse

    Pielke, R.A.; 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

  6. 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.

  7. Inaccuracy of liquid crystal thermometry to identify core temperature trends in postoperative adults.

    PubMed

    Vaughan, M S; Cork, R C; Vaughan, R W

    1982-03-01

    In 71 adult postsurgical patients, simultaneous measurement of core (tympanic membrane) and shell (liquid crystal adhesive temperature strip) cutaneous temperature was assessed on admission and every 15 minutes throughout the recovery room stay. Tympanic membrane sensors were inserted into the ear and adhesive temperature strips were applied to the forehead. Although temperature strip temperatures on admission to the recovery room were correlated significantly with tympanic membrane temperatures on admission to the recovery room (r = 0.61, p less than 0.001), subsequent readings 15, 30, 45, and 60 minutes after admission demonstrated decreasing correlation coefficients. Moreover, changes in temperature strip temperatures over the first 15, 30, and 45 minutes of monitoring in the recovery room did not correlate significantly with changes in tympanic membrane temperatures over the same time period. These data suggest that shell temperature (temperature strip) is not a reliable or valid trend indicator of core temperature (tympanic membrane) in postanesthetic adults.

  8. 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

  9. Recent trend analysis of mean air temperature in Greece based on homogenized data

    NASA Astrophysics Data System (ADS)

    Mamara, A.; Argiriou, A. Α.; Anadranistakis, M.

    2016-11-01

    Numerous studies analyze the temperature variations in the Mediterranean area due to the anticipated impact of climate change in this part of the world. A number of studies examined the temperature climate in Greece, but few are based on a large number of synoptic stations covering all regions and climatic zones and even fewer are based on homogenized data set series, despite the fact that climatological studies must use high-quality homogeneous data series. The present work reviews previous studies dealing with climatic changes in Greece and addresses changes of mean air temperature, based on a large set of homogenized data from 52 synoptic stations. A statistically significant negative trend during 1960-1976 and a positive one during 1977-2004 were revealed. During 1960-1976, the lowest negative annual temperature trend is observed in Crete. During 1977-2004, the northern region of Greece was characterized by prominent annual warming, whereas the north and central Aegean Sea and the semi-mountainous area were characterized by the lowest warming. All stations are characterized by high seasonal trends in summer; the most extreme trends are observed in the northern and eastern regions and in the Attica area. Positive temperature trends occur from May to October, while negative trends dominate from November to February. The most pronounced warming is recorded in June and July, and the most strongly decreasing trend occurs in November. Annual temperature trends in northern Greece follow the hemispheric pattern, and the overall summer warming in Greece is greater than the hemisphere's.

  10. 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.

  11. 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.

  12. 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

  13. Can Significant Trends in Surface Temperature and Precipitation be Detected over South America?

    NASA Astrophysics Data System (ADS)

    Lee, H.; Mechoso, C. R.; de Barros Soares, D.; Barkhordarian, A.; Loikith, P. C.

    2015-12-01

    This paper explores the existence of significant trends in near-surface temperature and precipitation over the South American continent by using observational data and estimates of natural variability based on simulations with numerical climate models. Trends are computed from three observational datasets in the period 1975-2004 for temperature and 1955-2004 for precipitation. Significance of the trends is tested against the null hypothesis that they arise from natural variability alone, which is estimated from the output of a suite of CMIP5 pre-industrial control experiments. Trends obtained from the observational datasets are compared with those simulated by CMIP5 historical runs, in which observed external transient forcing is imposed, and with those from simulations with natural-only forcing. In the case of temperature, an overall warming trend is found over the entire South American continent (0.23 C per decade). Significant trends (at the 95% level) are found in a region that corresponds roughly to Brazil with maximum warming over the north-central part. The average trends over South America in the observations broadly agree with those in the CMIP5 historical simulations for all seasons. This agreement is less close for the natural-only forcing simulations. The maximum warming over north-central Brazil is generally underestimated by the models. In the case of precipitation, trends vary both in sign and intensity according to region and season. The only significant trends in precipitation are obtained in La Plata Basin. Over the southern part of the basin (south of the Tropic of Capricorn), a significant decrease in precipitation is found during winter (-1.6 mm/month per decade) and an increase in all other seasons (4.2 mm/month per decade during summer). Over the northern part of La Plata Basin, the only significant trend in precipitation is a decrease during winter (-1.2 mm/month per decade).

  14. Temperature Sensing Using Linear and Nonlinear Resistive Fluidic Components

    DTIC Science & Technology

    1978-06-01

    SECURITY CLASSIFICATION OF THIS PAGE (When Data Entered) CONTENTS Page 1. INTRODUCTION 5 2. DESIGN CONCEPTS 5 2.1 Flow through Capillary 5 2.2...Comparison between test results and theoretical prediction of sensor outputs versus T2 12 1. INTRODUCTION Temperature sensing using fluidic...DRSMI-RBD ATTN DRDMI-TGC, WILLIAM GRIFFITH ATTN DRDMI-TGC, J. C. DUNAWAY ATTN DRCPM-TOE, FRED J. CHEPLEN COMMANDER USA MOBILITY EQUIPMENT R&D CENTER

  15. Trends of urban surface temperature and heat island characteristics in the Mediterranean

    NASA Astrophysics Data System (ADS)

    Benas, Nikolaos; Chrysoulakis, Nektarios; Cartalis, Constantinos

    2016-09-01

    Urban air temperature studies usually focus on the urban canopy heat island phenomenon, whereby the city center experiences higher near surface air temperatures compared to its surrounding non-urban areas. The Land Surface Temperature (LST) is used instead of urban air temperature to identify the Surface Urban Heat Island (SUHI). In this study, the nighttime LST and SUHI characteristics and trends in the seventeen largest Mediterranean cities were investigated, by analyzing satellite observations for the period 2001-2012. SUHI averages and trends were based on an innovative approach of comparing urban pixels to randomly selected non-urban pixels, which carries the potential to better standardize satellite-derived SUHI estimations. A positive trend for both LST and SUHI for the majority of the examined cities was documented. Furthermore, a 0.1 °C decade-1 increase in urban LST corresponded to an increase in SUHI by about 0.04 °C decade-1. A longitudinal differentiation was found in the urban LST trends, with higher positive values appearing in the eastern Mediterranean. Examination of urban infrastructure and development factors during the same period revealed correlations with SUHI trends, which can be used to explain differences among cities. However, the majority of the cities examined show considerably increased trends in terms of the enhancement of SUHI. These findings are considered important so as to promote sustainable urbanization, as well as to support the development of heat island adaptation and mitigation plans in the Mediterranean.

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

    SciTech Connect

    McCormack, J.P.; Hood, H.L.

    1994-07-15

    A one-dimensional radiative transfer model with fixed dynamical heating is used to calculate the approximate latitude and seasonal dependences of lower stratospheric temperature changes associated with observed ozone trends. The spatial and temporal distribution of ozone profile trends in the lower stratosphere is estimated from a combination of Nimbus 7 Solar Backscattered Ultraviolet (SBUV) global measurements of the ozone column below 32 mbar for the period 1979-1990 and balloon ozonesonde profile trends at northern middle latitudes. The calculated temperature trends near 100 mbar compare favorably with those recently derived by Randel and Cobb using data from Channel 4 of the Microwave Sounding Unit (MSU) on the NOAA operational satellites, although a number of quantitative differences are found. An independent analysis reported here of 100 mbar temperatures derived from northern hemisphere radiosonde data at the Free University of Berlin supports the validity of the satellite-derived lower stratospheric temperature trends. These results are therefore generally consistent with the hypothesis that observed lower stratospheric cooling trends are predominantly determined by reductions in radiative heating associated with stratospheric ozone depletion. 16 refs., 4 figs., 1 tab.

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

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

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

  18. 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.

  19. Performance Testing of a High Temperature Linear Alternator for Stirling Convertors

    NASA Technical Reports Server (NTRS)

    Metscher, Jonathan; Geng, Steven

    2016-01-01

    The NASA Glenn Research Center has conducted performance testing of a high temperature linear alternator (HTLA) in support of Stirling power convertor development for potential future Radioisotope Power Systems (RPS). The high temperature linear alternator is a modified version of that used in Sunpowers Advanced Stirling Convertor (ASC), and is capable of operation at temperatures up to 200 C. Increasing the temperature capability of the linear alternator could expand the mission space of future Stirling RPS designs. High temperature Neodymium-Iron-Boron (Nd-Fe-B) magnets were selected for the HTLA application, and were fully characterized and tested prior to uses. Higher temperature epoxy for alternator assembly was also selected and tested for thermal stability and strength. A characterization test was performed on the HTLA to measure its performance at various amplitudes, loads, and temperatures. HTLA endurance testing at 200 C is currently underway.

  20. Performance Testing of a High Temperature Linear Alternator for Stirling Convertors

    NASA Technical Reports Server (NTRS)

    Metscher, Jonathan F.; Geng, Steven M.

    2016-01-01

    The NASA Glenn Research Center has conducted performance testing of a high temperature linear alternator (HTLA) in support of Stirling power convertor development for potential future Radioisotope Power Systems (RPS). The high temperature linear alternator is a modified version of that used in Sunpower's Advanced Stirling Convertor (ASC), and is capable of operation at temperatures up to 200 deg. Increasing the temperature capability of the linear alternator could expand the mission set of future Stirling RPS designs. High temperature Neodymium-Iron-Boron (Nd-Fe-B) magnets were selected for the HTLA application, and were fully characterized and tested prior to use. Higher temperature epoxy for alternator assembly was also selected and tested for thermal stability and strength. A characterization test was performed on the HTLA to measure its performance at various amplitudes, loads, and temperatures. HTLA endurance testing at 200 deg is currently underway.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  2. 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.

  3. 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.

  4. Reconciling observed and modeled temperature and precipitation trends over Europe by adjusting for circulation variability

    NASA Astrophysics Data System (ADS)

    Saffioti, Claudio; Fischer, Erich M.; Scherrer, Simon C.; Knutti, Reto

    2016-08-01

    Europe experienced a pronounced winter cooling of about -0.37°C/decade in the period 1989-2012, in contrast to the strong warming simulated by the Coupled Model Intercomparison Project Phase 5 multimodel average during the same period. Even more pronounced discrepancies between observed and simulated short-term trends are found at the local scale, e.g., a strong winter cooling over Switzerland and a pronounced reduction in precipitation along the coast of Norway. We show that monthly sea level pressure variability accounts for much of the short-term variations of temperature over most of the domain and of precipitation in certain regions. Removing the effect of atmospheric circulation through a regression approach reconciles the observed temperature trends over Europe and Switzerland and the precipitation trend along the coast of Norway with the corresponding multimodel mean trends.

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

    NASA Astrophysics Data System (ADS)

    Franquist, Eric S.

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

  6. Trends and temperature sensitivity of moisture conditions in the conterminous United States

    USGS Publications Warehouse

    McCabe, G.J.; Wolock, D.M.

    2002-01-01

    Observed (1895-1999) trends in climatic moisture conditions in the conterminous United States (US) characterized by (1) annual precipitation minus annual potential evapotranspiration (PMPE), (2) annual surplus (water that eventually becomes streamflow), and (3) annual deficit (the amount of water that must be supplied by irrigation to grow vegetation at an optimum rate) are examined. The sensitivity of moisture conditions across the conterminous US to increases in temperature also are examined. Results indicate that there have been statistically significant trends in PMPE, annual surplus, and annual deficit for some parts of the conterminous US. Most of the significant trends in PMPE have been increasing trends primarily in the eastern US. Annual surplus also has increased over the eastern US, whereas the magnitudes of annual deficit have decreased. For the conterminous US as a whole, there has been a statistically significant increase in PMPE and annual surplus; however, there is no significant trend in annual deficit. Results also indicate that PMPE and annual deficit in the warmest regions of the conterminous US are most sensitive to increase in temperature. The high sensitivity of PMPE and annual deficit in these regions to increases in temperature is related to the relation between temperature and the saturation vapor pressure of air. The increases in potential evapotranspiration for a given change in temperature are larger for high temperatures than for low temperatures. The regions with the highest sensitivity of annual surplus to increases in temperature are the humid regions of the country. In these regions, annual surplus is large and increased potential evapotranspiration, resulting from increased temperature, has a significant effect on reducing annual surplus. In the dry regions of the country, annual surplus is so low that increases in potential evapotranspiration only result in small decreases in annual surplus.

  7. 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.

  8. 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

  9. Contribution of the Interdecadal Pacific Oscillation to twentieth-century global surface temperature trends

    NASA Astrophysics Data System (ADS)

    Meehl, Gerald A.; Hu, Aixue; Santer, Benjamin D.; Xie, Shang-Ping

    2016-11-01

    Longer-term externally forced trends in global mean surface temperatures (GMSTs) are embedded in the background noise of internally generated multidecadal variability. A key mode of internal variability is the Interdecadal Pacific Oscillation (IPO), which contributed to a reduced GMST trend during the early 2000s. We use a novel, physical phenomenon-based approach to quantify the contribution from a source of internally generated multidecadal variability--the IPO--to multidecadal GMST trends. Here we show that the largest IPO contributions occurred in its positive phase during the rapid warming periods from 1910-1941 and 1971-1995, with the IPO contributing 71% and 75%, respectively, to the difference between the median values of the externally forced trends and observed trends. The IPO transition from positive to negative in the late-1990s contributed 27% of the discrepancy between model median estimates of the forced part of the GMST trend and the observed trend from 1995 to 2013, with additional contributions that are probably due to internal variability outside of the Pacific and an externally forced response from small volcanic eruptions. Understanding and quantifying the contribution of a specific source of internally generated variability--the IPO--to GMST trends is necessary to improve decadal climate prediction skill.

  10. 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.

  11. 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.

  12. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

    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.

  14. Observed warming trend in sea surface temperature at tropical cyclone genesis

    NASA Astrophysics Data System (ADS)

    Defforge, Cécile L.; Merlis, Timothy M.

    2017-01-01

    Tropical cyclone (TC) activity is influenced by environmental factors, and it is expected to respond to anthropogenic climate change. However, there is observational uncertainty in historical changes in TC activity, and attributing observed TC changes to anthropogenic forcing is challenging in the presence of internal climate variability. The sea surface temperature (SST) is a well-observed environmental factor that affects TC intensity and rainfall. Here we show that the SST at the time of TC genesis has a significant warming trend over the three decades of the satellite era. Though TCs are extreme events, the warming trend at TC genesis is comparable to the trend in SST during other tropical deep convection events and the trend in SST in the TC main development regions throughout the TC season. This newly documented, observed signature of climate change on TC activity is also present in high-resolution global atmospheric model simulations that explicitly simulate TCs.

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

    PubMed

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

    2013-04-01

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

  16. 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.

  17. Comparison of Temperature Trends Using an Unperturbed Subset of The U.S. Historical Climatology Network

    NASA Astrophysics Data System (ADS)

    Watts, A. W.; Jones, E. M.; Nielsen-Gammon, J. W.; Christy, J. R.

    2015-12-01

    Climate observations are affected by variations in land use and land cover at all scales, including the microscale.A 410-station subset of U.S. Historical Climatology Network (version 2.5) stations is identified that experienced no changes in time of observation or station moves during the 1979-2008 period. These stations are classified based on proximity to artificial surfaces, buildings, and other such objects with unnatural thermal mass using guidelines established by Leroy (2010). The relatively few stations in the classes with minimal artificial impact are found to have raw temperature trends that are collectively about 2/3 as large as stations in the classes with greater expected artificial impact. The trend differences are largest for minimum temperatures and are statistically significant even at the regional scale and across different types of instrumentation and degrees of urbanization. The homogeneity adjustments applied by the National Centers for Environmental Information (formerly the National Climatic Data Center) greatly reduce those differences but produce trends that are more consistent with the stations with greater expected artificial impact. Trend differences between the Cooperative Observer Network and the Climate Reference Network are not found during the 2005-2014 sub-period of relatively stable temperatures, suggesting that the observed differences are caused by a physical mechanism that is directly or indirectly caused by changing temperatures.

  18. 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.

  19. 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.

  20. Ambient temperature and violent crime: tests of the linear and curvilinear hypotheses.

    PubMed

    Anderson, C A; Anderson, D C

    1984-01-01

    Laboratory research on the effects of temperature has led theorists to propose a curvilinear model relating negative affect and aggression. Two alternative explanations of these lab findings are proposed--one artifactual, one based on attributions for arousal. Both alternatives predict a linear relationship between temperature and aggression in real-world settings, whereas the negative affect curvilinear model predicts a specific curvilinear effect. Two studies are reported that investigated the relationship between temperature and violent crime. Both studies yielded significant linear relationships and failed to demonstrate the specified curvilinear relationship. Also, both studies yielded significant day-of-the-week effects. Implications of these findings for the study of aggression are discussed.

  1. Urban and peri-urban precipitation and air temperature trends in mega cities of the world using multiple trend analysis methods

    NASA Astrophysics Data System (ADS)

    Ajaaj, Aws A.; Mishra, Ashok K.; Khan, Abdul A.

    2017-03-01

    Urbanization plays an important role in altering local to regional climate. In this study, the trends in precipitation and the air temperature were investigated for urban and peri-urban areas of 18 mega cities selected from six continents (representing a wide range of climatic patterns). Multiple statistical tests were used to examine long-term trends in annual and seasonal precipitation and air temperature for the selected cities. The urban and peri-urban areas were classified based on the percentage of land imperviousness. Through this study, it was evident that removal of the lag-k serial correlation caused a reduction of approximately 20 to 30% in significant trend observability for temperature and precipitation data. This observation suggests that appropriate trend analysis methodology for climate studies is necessary. Additionally, about 70% of the urban areas showed higher positive air temperature trends, compared with peri-urban areas. There were not clear trend signatures (i.e., mix of increase or decrease) when comparing urban vs peri-urban precipitation in each selected city. Overall, cities located in dry areas, for example, in Africa, southern parts of North America, and Eastern Asia, showed a decrease in annual and seasonal precipitation, while wetter conditions were favorable for cities located in wet regions such as, southeastern South America, eastern North America, and northern Europe. A positive relationship was observed between decadal trends of annual/seasonal air temperature and precipitation for all urban and peri-urban areas, with a higher rate being observed for urban areas.

  2. 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.

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

    PubMed

    Wen, Qiang; Lian, Su-Jie; Zhang, Chen; Zhao, Hui; Zhao, Yu; Wang, Gao; Xu, De-Gang; Yao, Jian-Quan

    2014-03-01

    In order to obtain the different position temperature changes in the process of explosive casting accurate, stability and comprehensive, we designed the temperature monitoring system based on fiber Bragg grating spectral shift. Through the fiberoptic network, the system can monitor the different point temperature of melt-cast explosive real-time. According to the function of linear frequency shift of fiber Bragg grating wavelength with the grating of temperature, we get the temperature of different positions. Four channels share a broadband light source with a coupler. The Bragg wavelengths of the 5 gratings of each fiber are separated from each other. Using the gratings designed, spliced and packaged by our own, we can obtain temperature data through the demodulator. The temperature data was processed by the Origin to draw diagram time-temperature curve. The results show that the measured temperature data of the fiber Bragg grating can meet the requirements of experiment.

  4. High-temperature piezoelectric materials for elements of linear piezo motors

    NASA Astrophysics Data System (ADS)

    Khramtsov, A. M.; Spitsin, A. I.; Segalla, A. G.; Ponomarev, S. V.; Rikkonen, S. V.

    2016-11-01

    This paper discusses technological and construction ways to achieve a high working temperature with a high displacement in linear piezo motors. The first part reviews the results of the piezoelectric material development, its temperature stability testing and basic parameters for piezo motors. The second part focuses on the multilayer structure of piezoelectric elements, which are based on high-temperature piezoelectric materials (HTPM). Also analyzed are working temperatures of multilayer piezoelectric elements (MPE) and their hysteresis. Finally, the third part shows a comparison of three recent prototypes of high-temperature MPEs that were in our lab using different materials.

  5. 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.

  6. The contribution of greenhouse gases to the recent slowdown in global-mean temperature trends

    NASA Astrophysics Data System (ADS)

    Checa-Garcia, R.; Shine, K. P.; Hegglin, M. I.

    2016-09-01

    The recent slowdown in the rate of increase in global-mean surface temperature (GMST) has generated extensive discussion, but little attention has been given to the contribution of time-varying trends in greenhouse gas concentrations. We use a simple model approach to quantify this contribution. Between 1985 and 2003, greenhouse gases (including well-mixed greenhouse gases, tropospheric and stratospheric ozone, and stratospheric water vapour from methane oxidation) caused a reduction in GMST trend of around 0.03-0.05 K decade-1 which is around 18%-25% of the observed trend over that period. The main contributors to this reduction are the rapid change in the growth rates of ozone-depleting gases (with this contribution slightly opposed by stratospheric ozone depletion itself) and the weakening in growth rates of methane and tropospheric ozone radiative forcing. Although CO2 is the dominant greenhouse gas contributor to GMST trends, the continued increase in CO2 concentrations offsets only about 30% of the simulated trend reduction due to these other contributors. These results emphasize that trends in non-CO2 greenhouse gas concentrations can make significant positive and negative contributions to changes in the rate of warming, and that they need to be considered more closely in analyses of the causes of such variations.

  7. Surface Temperature Trends in the Arctic and the Antarctic from AVHRR and In Situ Data

    NASA Astrophysics Data System (ADS)

    Perez, G. J. P.; Comiso, J. C.

    2015-12-01

    The earliest signals of a climate change are expected to be observed in the polar regions in part because of the high reflectively of snow and ice. Because of general inaccessibility, there is a 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 two regions. The sensor with the longest satellite record on temperature has been the NOAA/Advanced Very High Resolution Radiometer (AVHRR) that has provided continuous thermal infrared data for more than 33 years. The results of analysis of the data show that there is indeed a strong signal coming from the Arctic with the trend in surface temperature (for the region > 64°N) being 0.6°C per decade which is about 3 times the global trend of 0.2°C per decade for the same period. It appeared surprising when the results from a similar region (> 64 °S) in the Antarctic show a much lower trend and comparable to the global trend. The primary source of error in the temperature data is cloud masking associated with the similar signatures of clouds and snow/ice covered surfaces. However, the derived AVHRR data show good consistency with in situ data with standard deviation less than 1°C. The AVHRR time series has also been compared and showed compatibility with data from the Aqua/Moderate Resolution Imaging Spectroradiometer (MODIS) which have been available from 2000 to the present. Some differences in the trends from the two hemispheres are expected because of very different geographical environments in the two regions. The relationships of the trend with the atmospheric global circulation in the north, as defined by the Northern Annular Mode (NAM), and that in the south, as defined by the Southern Annular Mode (SAM), have been observed to be generally weak. The occurrences of the Antarctic Circumpolar Wave (ACW) and ENSO were also studied and not considered a significant factor. It is intriguing that the observed variability in

  8. Ratios of Record High to Record Low Temperatures in Europe Show an Accelerating Trend Since 2000 Despite a Slowdown in Mean Temperature Trends

    NASA Astrophysics Data System (ADS)

    Beniston, M.

    2014-12-01

    The present study has examined the behavior of extreme high and low temperatures in Euirope since the mid-20th century, in terms of the ratio of number of days per year with record Tmax and record Tmin. The investigations have shown that there has been a clear and massive increase in the number of high Tmax: low Tmin ratios in the most recent decade of the 1951-2013 temperature record for 30 selected observation stations in Europe. This sharp increase is seen to occur despite an apparent hiatus - or at least a reduction in the rate of warming - since the early 2000s, as observed not only in Europe but on a hemispheric basis too. The «explosion» of record high:record low temperature ratios since 2000, despite relatively small increases in mean temperatures in the last 10-15 years of the observational record, can be explained by a non-linear (quadratic) relation between mean temperatures and the Tmax:Tmin record ratios. It is suggested here that the increases are probably a consequence of increasing dryness during the summer in the Mediterranean region (where today there are on average 30 more dry days than in the 1950s), and a reduction in the cold season conducive to snow days in Arctic summers and Northern European springs (with up to 40 days less freezing days than 60 years previously). Both effects can serve to amplify positive temperature feedbacks in the lower atmosphere that result in strong increases in the number of Tmax record high temperatures and correspondingly strong reductions in the number of Tmin record low temperatures.

  9. 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

  10. A high-temperature double-mode piezoelectric ultrasonic linear motor

    NASA Astrophysics Data System (ADS)

    Li, Xiaotian; Chen, Jianguo; Chen, Zhijiang; Dong, Shuxiang

    2012-08-01

    A miniature piezoelectric ultrasonic linear motor (piezoelectric vibrator sizes: 4.7 × 13.5 × 2 mm3) has been studied for precise actuation at 200 °C high-temperature. This piezoelectric linear motor was made of (1-x)BiScO3-xPbTiO3 piezoelectric ceramic with a high curie temperature (428 °C) and it was operated in first longitudinal and the second bending double-mode. Our experimental results showed that the linear motor moves smoothly at the temperature as high as 200 °C with a driving force of 0.35 N and a speed up to 42 mm/s.

  11. Characterizing the urban temperature trend using seasonal unit root analysis: Hong Kong from 1970 to 2015

    NASA Astrophysics Data System (ADS)

    To, Wai-Ming; Yu, Tat-Wai

    2016-12-01

    This paper explores urban temperature in Hong Kong using long-term time series. In particular, the characterization of the urban temperature trend was investigated using the seasonal unit root analysis of monthly mean air temperature data over the period January 1970 to December 2013. The seasonal unit root test makes it possible to determine the stochastic trend of monthly temperatures using an autoregressive model. The test results showed that mean air temperature has increased by 0.169°C (10 yr)-1 over the past four decades. The model of monthly temperature obtained from the seasonal unit root analysis was able to explain 95.9% of the variance in the measured monthly data — much higher than the variance explained by the ordinary least-squares model using annual mean air temperature data and other studies alike. The model accurately predicted monthly mean air temperatures between January 2014 and December 2015 with a root-mean-square percentage error of 4.2%. The correlation between the predicted and the measured monthly mean air temperatures was 0.989. By analyzing the monthly air temperatures recorded at an urban site and a rural site, it was found that the urban heat island effect led to the urban site being on average 0.865°C warmer than the rural site over the past two decades. Besides, the results of correlation analysis showed that the increase in annual mean air temperature was significantly associated with the increase in population, gross domestic product, urban land use, and energy use, with the R2 values ranging from 0.37 to 0.43.

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

    NASA Astrophysics Data System (ADS)

    Camberlin, Pierre

    2017-01-01

    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

  13. Trends of surface humidity and temperature during 1951-2012 in Beijing, China

    NASA Astrophysics Data System (ADS)

    Chu, Q.; Xu, Z.; Peng, D.; Yang, X.; Yang, G.

    2015-05-01

    In this paper, two datasets, a long time series (1951-2012) of daily surface observations at one meteorological station and a shorter time series (1979-2012) of three-hourly data with 0.1°×0.1° spatial resolution were analysed by using non-parametric methods to identify annual and seasonal variations in surface humidity and temperature. The results reveal that: (1) saturation water vapour pressure increased exponentially with temperature. Actual daily values at Beijing Meteorological Station are very close to the theoretical values estimated by using the simplified Clausius-Clapeyron equation, but with seasonal variations. (2) For both long- and short-term data, clear increasing tendencies of annual saturation specific humidity and temperature are found. Decreasing and drying trends were detected for winter. (3) The annual relative humidity showed a decreasing trend except for some suburban areas, somehow related to the lower temperature and increased specific humidity in those areas. (4) Regional changes in topography and elevation likely influenced trends in surface humidity, while local land use showed little effect on it.

  14. On estimation and attribution of long-term temperature trends in the thermosphere

    NASA Astrophysics Data System (ADS)

    Akmaev, R. A.

    2012-09-01

    Recent analyses of long-term time series of ion temperature from two midlatitude incoherent-scatter radars have revealed very strong cooling, which is substantially greater than predicted by models for neutral temperature. There is also an indication that the cooling has substantially accelerated after a breakpoint around 1979 when the ozone hole was discovered. This has prompted a hypothesis that the accelerated cooling might have resulted from the ozone depletion and associated reduction in daytime radiative heating in the stratosphere. A lively discussion on relative roles of different cooling mechanisms has followed. The purpose of this note is to contribute to this discussion from a theoretical and modeling perspective. In particular, a possible misinterpretation of the modeling results behind the ozone hypothesis is clarified. It is also shown that model predictions of neutral temperature trends in the thermosphere agree well with, and hence are tightly constrained by, independent observations including trends in heights of ionospheric layers and in neutral density from satellite drag. However, they are up to an order of magnitude smaller than the observational estimates of trends in ion temperature. These widely different results cannot be quantitatively reconciled regardless of what known cooling mechanisms are invoked. This stark discrepancy should be addressed on the data analysis and theoretical fronts.

  15. 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.

  16. 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.

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

    NASA Astrophysics Data System (ADS)

    Lebedev, S. A.

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

  18. 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.

  19. 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

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

    PubMed

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

    2016-01-30

    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.

  1. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. Unusual linear dependency of viscosity with temperature in ionic liquid/water mixtures.

    PubMed

    Nanda, R

    2016-09-21

    An unusual linear dependency of viscosity with temperature has been observed in aqueous solutions of 1-octyl-3-methylimidazolium-based ionic liquids because of the ion induced structural transition which leads to the violation of both the Stokes-Einstein and fractional Stokes-Einstein equations, suggesting the presence of dynamic heterogeneity in the system.

  8. 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.

  9. 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

    2016-07-12

    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 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.

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

    DOE PAGES

    Bang, Woosuk; Albright, Brian James; Bradley, Paul Andrew; ...

    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

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

    SciTech Connect

    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 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. In conclusion, these simulations offer useful insight into the expansion of warm dense matter and motivate the application of optical shadowgraphy for temperature measurement.

  12. Linear electrostatic waves in two-temperature electron-positron plasmas

    NASA Astrophysics Data System (ADS)

    Lazarus, I. J.; Bharuthram, R.; Singh, S. V.; Pillay, S. R.; Lakhina, G. S.; Lakhina

    2012-12-01

    Linear electrostatic waves in a magnetized four-component, two-temperature electron-positron plasma are investigated, with the hot species having the Boltzmann density distribution and the dynamics of cooler species governed by fluid equations with finite temperatures. A linear dispersion relation for electrostatic waves is derived for the model and analyzed for different wave modes. Analysis of the dispersion relation for perpendicular wave propagation yields a cyclotron mode with contributions from both cooler and hot species, which in the absence of hot species goes over to the upper hybrid mode of cooler species. For parallel propagation, both electron-acoustic and electron plasma modes are obtained, whereas for a single-temperature electron-positron plasma, only electron plasma mode can exist. Dispersion characteristics of these modes at different propagation angles are studied numerically.

  13. The contribution of atmospheric circulation to decadal trends in northern hemisphere temperature

    NASA Astrophysics Data System (ADS)

    Iles, Carley; Hegerl, Gabriele

    2016-04-01

    The early twentieth century (1920s-1940s) was characterised by a warming period, concentrated particularly in the Arctic in winter. The causes of this Arctic warming are not completely understood but a combination of internal variability and external forcing has been suggested. Here we investigate the contribution of atmospheric circulation to this northern hemisphere warming trend. We identify the atmospheric pressure patterns that occurred during this period using reanalysis data. We then calculate their contribution to the observed winter temperature trends through an analogue technique in which similar atmospheric circulation patterns are identified in interannual variability across the whole twentieth century, and their relationship to northern hemisphere temperature calculated through regression. We also examine the contribution of other known atmospheric modes to northern hemisphere temperature during this period and for other periods of increasing and decreasing temperature, including the North Atlantic Oscillation/ Arctic Oscillation and the Cold Ocean Warm Land Pattern, which is associated with warm air advection from ocean to land in the northern hemisphere in winter.

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

    PubMed

    Divall, S A; Humphrey, V F

    2000-03-01

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

  15. 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

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

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

    Larko, Aleksandr; Shevyrnogov, Anatoly

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

  18. 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.

  19. 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;

  20. 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.

  1. 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.

  2. 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.

  3. 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.

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

    PubMed

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

    2009-09-15

    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.

  5. The investigation of temperature trend in the Antarctic using GPS radio occultation technique

    NASA Astrophysics Data System (ADS)

    Fu, E.

    2010-12-01

    The Antarctic plays a vital role in the global atmospheric and oceanic systems and circulations because of its unique geographical and meteorological features. In recent years, abnormal melting of Antarctica ice sheet has been considered as a strong evidence of global warming. The phenomenon itself has significant feedback to the weather and climate processes. Climate change in the Antarctic and its impacts on global climate have drawn more and more attention of climatologists. Some studies have presented general warming trend of near-surface temperature in the Antarctic but cooling trends in some regions and seasons. Turner (2006) reported warming trend in the upper troposphere and cooling trend in the lower stratosphere. Most studies on the Antarctic meteorology and climatology predominately relies on only 18 weather stations operated by different countries. All these stations (expect the Amundsen-Scott station) are distributed along the coastline. The number and locations of these stations is inappropriate for the whole Antarctic continent area. Moreover, the extreme weather environment result in observations poor in both quantity and quality. The recently available atmospheric profiles derived from the Global Positioning System (GPS) radio occultation (RO) technique have demonstrated a great potential for advancing weather and climate studies, especially for remote areas such as the ocean and polar regions. The CHAMP mission provides nearly eight years (2001 - 2008) atmospheric data by using the GPS RO technique. COSMIC generates about 2,500 atmospheric profiles daily since 2006. Due to the global coverage of the GPS RO observations, a great number of high quality atmospheric information can be obtained over the Antarctic area. This study is to investigate the potential of using the GPS RO technique for the Antarctic climate monitoring. Although only eight-year CHAMP data available, the result has shown the significance of the GPS RO technique for reliable and

  6. Sensitivity of terrestrial precipitation trends to the structural evolution of sea surface temperatures

    NASA Astrophysics Data System (ADS)

    Anderson, Bruce T.; Lintner, Benjamin R.; Langenbrunner, Baird; Neelin, J. David; Hawkins, Ed; Syktus, Jozef

    2015-02-01

    Pronounced intermodel differences in the projected response of land surface precipitation (LSP) to future anthropogenic forcing remain in the Coupled Model Intercomparison Project Phase 5 model integrations. A large fraction of the intermodel spread in projected LSP trends is demonstrated here to be associated with systematic differences in simulated sea surface temperature (SST) trends, especially the representation of changes in (i) the interhemispheric SST gradient and (ii) the tropical Pacific SSTs. By contrast, intermodel differences in global mean SST, representative of differing global climate sensitivities, exert limited systematic influence on LSP patterns. These results highlight the importance to regional terrestrial precipitation changes of properly simulating the spatial distribution of large-scale, remote changes as reflected in the SST response to increasing greenhouse gases. Moreover, they provide guidance regarding which region-specific precipitation projections may be potentially better constrained for use in climate change impact assessments.

  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. Linearity, climate sensitivity and climate changes in the surface temperature field

    NASA Astrophysics Data System (ADS)

    Stainforth, D. A.; Smith, L. A.

    2012-04-01

    The relationship between equilibrium global mean temperature, Te, and applied radiative forcing, Rf, is commonly expressed by the linear equation (Gregory et al., Roe and Baker): ΔTe = λ Rf where λ is a constant known as the feedback parameter. Here we address the question of whether the relationship between Te and Rf is, in fact, well quantified by such a linear equation. Our analysis is based on the output of a global climate model. If the relationship breaks down when moving from a single equation model to a complicated global circulation model it is unlikely to reassert itself in the real world with all its additional complexity. Thus nonlinearity in the model can be taken as a strong indication of nonlinearity in reality, while linearity in a model might only be taken as a weak indication of linearity in reality. Thanks to the support of the climateprediction.net team and participants, we were able to run large (>500 members) initial condition ensembles with a global climate model (HadSM3) at seven values of Rf. Results will be presented demonstrating the nonlinear nature of the Te, Rf relationship. The term "linear" is used with a number of different meanings, leading to confusion in discussions between the many disciplines involved in climate science research. Furthermore, in the high-dimensional space of climate model output, linearity with Rf can be achieved in a variety of ways: for instance, linearity in magnitude of change (as in the equation above), linearity in degree of rotation within the high-dimensional model state space, linear change in variance in each dimension. These will be illustrated. Analysis of the above ensembles will be used to show that not only is the model nonlinear in the scalar global mean temperature, but also in the pattern of change. These results imply key messages for ensemble design. Most crucial is consideration of larger initial condition ensembles than is typical in climate model experiments. Such ensembles allow the

  9. 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.

  10. 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.

  11. Variability and trends in dynamical forcing of tropical lower stratospheric temperatures

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  12. 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.

  13. 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

  14. 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

  15. 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.

  16. 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.

  17. 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

  18. Air- and stream-water-temperature trends in the Chesapeake Bay region, 1960-2014

    USGS Publications Warehouse

    Jastram, John D.; Rice, Karen C.

    2015-12-14

    in-stream sediments, so understanding changes in stream-water temperature throughout the bay watershed is critical to resource managers seeking to restore the bay ecosystem.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. Decadal trends of temperature and salinity on the Western Mediterranean Coast ('Warm Coast' of Spain)

    NASA Astrophysics Data System (ADS)

    Plaza-Jorge, F.; Fraile-Nuez, E.

    2006-12-01

    Important annual significant increases of temperature and salinity values have been found to the north of the Almería-Orán Front (Murcia slope), with rates of 0.028±0.028°C and 0.008±0.007, respectively. This warming neither depends on a seasonal nor an annual cycle. The annual rate of heat content due to this temperature increase is 0.85±0.73 W m-2; this lies between the two values reported by Béthoux et al. [1990] and Várgas-Yáñez et al. [2002]. A positive decadal trend in the average pressure of the isopycnal levels produces an upward motion of 43 m from 100 to 180 m depth. Another phenomena detected was the presence of Western Intermediate Water (WIW) in the upper 200 m in 1996, 2000, 2003 and 2004.

  20. 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

  1. 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.

  2. Interrelationship of rainfall, temperature and reference evapotranspiration trends and their net response to the climate change in Central India

    NASA Astrophysics Data System (ADS)

    Kundu, Sananda; Khare, Deepak; Mondal, Arun

    2016-09-01

    The monthly rainfall data from 1901 to 2011 and maximum and minimum temperature data from 1901 to 2005 are used along with the reference evapotranspiration (ET0) to analyze the climate trend of 45 stations of Madhya Pradesh. ET0 is calculated by the Hargreaves method from 1901 to 2005 and the computed data is then used for trend analysis. The temporal variation and the spatial distribution of trend are studied for seasonal and annual series with the Mann-Kendall (MK) test and Sen's estimator of slope. The percentage of change is used to find the rate of change in 111 years (rainfall) and 105 years (temperatures and ET0). Interrelationships among these variables are analyzed to see the dependency of one variable on the other. The results indicate a decreasing rainfall and increasing temperatures and ET0 trend. A similar pattern is noticeable in all seasons except for monsoon season in temperature and ET0 trend analysis. The highest increase of temperature is noticed during post-monsoon and winter. Rainfall shows a notable decrease in the monsoon season. The entire state of Madhya Pradesh is considered as a single unit, and the calculation of overall net change in the amount of the rainfall, temperatures (maximum and minimum) and ET0 is done to estimate the total loss or gain in monthly, seasonal and annual series. The results show net loss or deficit in the amount of rainfall and the net gain or excess in the temperature and ET0 amount.

  3. Changing Trends and Variance in Eastern Equatorial Pacific Sea Surface Temperatures over the Twentieth Century

    NASA Astrophysics Data System (ADS)

    Jimenez, G.; Cole, J. E.; Thompson, D. M.; Tudhope, A. W.

    2015-12-01

    Global climate models and instrumental datasets often disagree regarding sea surface temperature (SST) trends in the tropical Pacific. Coral Sr/Ca records with sub-seasonal resolution provide SST proxies that complement and extend limited instrumental records. We present a new partially replicated Sr/Ca-SST record from two Galápagos corals (Isla Wolf, at 1°24'N, 91°48'W), that spans 1937-2010. The record shows high SST variance in the region, which increases nearly twofold after the late 1970s. Similarly, there is little trend in the mean until 1976, after which SSTs warm during all seasons. Both the increase in variance and the trend are strongest during the warm season, leading to progressively more anomalous conditions during El Niño events. To investigate recent changes in the eastern equatorial Pacific since the 1976/1977 climate transition, we compare the Galápagos record to a published coral Sr/Ca-SST record from Clipperton Atoll (10°18'N, 109°13'W, spanning 1874-1993; Wu et al., 2014, Palaeogeogr. Palaeoclimatol. Palaeoecol.). As in the Galápagos, Clipperton corals show increasing SSTs in all seasons after 1976. The trend at Clipperton is greater than in the Galápagos, though the variance is smaller and does not change significantly throughout the record. Finally, the north-south temperature gradient between Clipperton and Galápagos has increased slightly over the interval in which the two records overlap (1937-1993). Gridded instrumental SST data generally agree with the coral Sr/Ca-SST results, though the gridded data suggest lower variance at both sites. In sum, we show that an increase in the mean and variance of SSTs in the eastern equatorial Pacific is associated with an enhanced meridional SST gradient over the twentieth century, and especially since 1976. These results contrast with recent suggestions that a weakened meridional SST gradient in the equatorial Pacific may be leading to stronger El Niño events. Our results support the

  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. 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

  6. 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

  7. A high resolution model of linear trend in mass variations from DMT-2: Added value of accounting for coloured noise in GRACE data

    NASA Astrophysics Data System (ADS)

    Farahani, Hassan H.; Ditmar, Pavel; Inácio, Pedro; Didova, Olga; Gunter, Brian; Klees, Roland; Guo, Xiang; Guo, Jing; Sun, Yu; Liu, Xianglin; Zhao, Qile; Riva, Riccardo

    2017-01-01

    We present a high resolution model of the linear trend in the Earth's mass variations based on DMT-2 (Delft Mass Transport model, release 2). DMT-2 was produced primarily from K-Band Ranging (KBR) data of the Gravity Recovery And Climate Experiment (GRACE). It comprises a time series of monthly solutions complete to spherical harmonic degree 120. A novel feature in its production was the accurate computation and incorporation of stochastic properties of coloured noise when processing KBR data. The unconstrained DMT-2 monthly solutions are used to estimate the linear trend together with a bias, as well as annual and semi-annual sinusoidal terms. The linear term is further processed with an anisotropic Wiener filter, which uses full noise and signal covariance matrices. Given the fact that noise in an unconstrained model of the trend is reduced substantially as compared to monthly solutions, the Wiener filter associated with the trend is much less aggressive compared to a Wiener filter applied to monthly solutions. Consequently, the trend estimate shows an enhanced spatial resolution. It allows signals in relatively small water bodies, such as Aral sea and Ladoga lake, to be detected. Over the ice sheets, it allows for a clear identification of signals associated with some outlet glaciers or their groups. We compare the obtained trend estimate with the ones from the CSR-RL05 model using (i) the same approach based on monthly noise covariance matrices and (ii) a commonly-used approach based on the DDK-filtered monthly solutions. We use satellite altimetry data as independent control data. The comparison demonstrates a high spatial resolution of the DMT-2 linear trend. We link this to the usage of high-accuracy monthly noise covariance matrices, which is due to an accurate computation and incorporation of coloured noise when processing KBR data. A preliminary comparison of the linear trend based on DMT-2 with that computed from GSFC_global_mascons_v01 reveals, among

  8. Upper stratospheric and lower mesospheric thermal structure and temperature trends over a sub-tropical station, Mount Abu (24.5o N, 72.7o E)

    NASA Astrophysics Data System (ADS)

    Sharma, Som Kumar; Lal, S.; Chandra, Harish; Acharya, Y. B.

    -40, 41-45, 46-50 and 50-55 km for trends analysis. Linear Regression analysis is applied to calculate temperature trend in different altitude regions. Considering the imprints of seasonal, QBO and solar cycle variability, a decreasing temperature in the upper stratosphere and lower mesosphere has been found using the data from 1997-2008. Seasonally, trends are stronger during winter than during summer.

  9. 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.

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

    NASA Astrophysics Data System (ADS)

    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.

  11. 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.

  12. 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).

  13. The effective temperature of ions stored in a linear quadrupole ion trap mass spectrometer.

    PubMed

    Donald, William A; Khairallah, George N; O'Hair, Richard A J

    2013-06-01

    The extent of internal energy deposition into ions upon storage, radial ejection, and detection using a linear quadrupole ion trap mass spectrometer is investigated as a function of ion size (m/z 59 to 810) using seven ion-molecule thermometer reactions that have well characterized reaction entropies and enthalpies. The average effective temperatures of the reactants and products of the ion-molecule reactions, which were obtained from ion-molecule equilibrium measurements, range from 295 to 350 K and do not depend significantly on the number of trapped ions, m/z value, ion trap q z value, reaction enthalpy/entropy, or the number of vibrational degrees of freedom for the seven reactions investigated. The average of the effective temperature values obtained for all seven thermometer reactions is 318 ± 23 K, which indicates that linear quadrupole ion trap mass spectrometers can be used to study the structure(s) and reactivity of ions at near ambient temperature.

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

    PubMed

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

    2013-11-19

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

  15. Spatio-temporal trend analysis of precipitation, temperature, and river discharge in the northeast of Iran in recent decades

    NASA Astrophysics Data System (ADS)

    Minaei, Masoud; Irannezhad, Masoud

    2016-10-01

    This study analyses spatio-temporal trends in precipitation, temperature, and river discharge in the northeast of Iran during recent decades (1953-2013). The Pettitt, SNHT, Buishand, Box-Pierce, Ljung-Box, and McLeod-Li methods were applied to examine homogeneity in time series studied. The nonparametric Mann-Kendall and Sen's slope estimator tests were used to detect possible significant (p < 0.05) temporal trends in hydrometeorological time series and their magnitude, respectively. For time series with autocorrelation, the trend-free pre-whitening (TFPW) method was used to determine significant trends. To explore spatial distributions of trends, their magnitudes were interpolated by the inverse distance whitening (IDW) method. Trend analysis shows that for daily, monthly, and annual precipitation time series, 12.5, 19, and 12.5 % of the stations revealed significant increasing trends, respectively. For mean temperature, warming trends were found at 38, 23, and 31 % of the stations on daily, monthly, and annual timescales, in turn. Daily and monthly river discharge decreased at 80 and 40 % of the stations. Overall, these results indicate significant increases in precipitation and temperature but decreases in river discharge during recent decades. Hence, it can be concluded that decreasing trends in river discharge time series over the northeast of Iran during 1953-2013 are in response to warming temperatures, which increase the rate of evapotranspiration. Differences between the results of our comprehensive large-scale study and those of previous researches confirm the necessity for more model-based local studies on climatic and environmental changes across the northeast of Iran.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

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

    PubMed

    Levitán, D; D'Onofrio, A

    2012-09-01

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

  1. 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.

  2. Variation of output with atmospheric pressure and ambient temperature for Therac-20 linear accelerator.

    PubMed

    Sharma, S C; Wilson, D L; Jose, B

    1983-01-01

    The Therac-20 (a linear accelerator manufactured by the Atomic Energy of Canada, Ltd.) employs an unsealed monitor chamber to control the dose output. Daily fluctuations in machine output for both x rays and electron beams were observed to vary with ambient temperature and atmospheric pressure. These variations were not related to any other machine parameters. Variations as large as 3.5% were seen by monitoring 18-MV x-ray output over several months. We recommend that the manufacturers take steps to eliminate the atmospheric dependence of dose rate.

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

    SciTech Connect

    Manfredi, Pier F.; Re, Valerio

    2003-10-07

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

  4. 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

  5. Late Holocene Sea Surface Temperature Trends in the Eastern Tropical Pacific

    NASA Astrophysics Data System (ADS)

    Rustic, G. T.; Koutavas, A.; Marchitto, T. M., Jr.

    2015-12-01

    The Eastern Tropical Pacific (ETP) is a highly dynamic ocean region capable of exerting influencing on global climate as illustrated by the El Niño-Southern Oscillation (ENSO). The sea surface temperature (SST) history of this region in past millennia is poorly constrained due to the lack of in situ records with appropriate resolution. Here we present a ~2700 year sub-centennially resolved SST reconstruction from Mg/Ca ratios of the planktonic foraminifer Globigerinoides ruber from Galápagos sediments. The ETP SST record exhibits a long-term cooling trend of over 0.2°C/ky that is similar to Northern Hemisphere multi-proxy temperature trends suggesting a common origin, likely due to insolation forcing. The ETP remains in-phase with Northern Hemisphere climate records through the warm Roman Climate Optimum (~0-400CE), cooler Dark Ages Cold Period (~450-850CE), and through the peak warming of the Medieval Climate Anomaly (900-1150 CE) when SST is within error of modern. Following peak MCA, the ETP cooled rapidly and then rebounded at ~1500 CE during the coldest portion of the Little Ice Age. Overall the data suggest an out-of-phase relationship during much of the last millennium, which we attribute to dynamical adjustments consistent with the "dynamical ocean thermostat" mechanism. Further evidence for these dynamical adjustments comes from reconstructions of the east-west zonal SST gradient using existing Mg/Ca SST reconstructions from the western Pacific warm pool. The last millennium has been the most dynamic period over the past 2700 years, with significant (~1 °C) SST variability in the ETP and modulation of the zonal gradient. A combination of dynamical and thermodynamic mechanisms are invoked to explain the region's complex SST history.

  6. 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

  7. 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.

  8. The potential of explaining low-frequency temperature variability by a linear model

    NASA Astrophysics Data System (ADS)

    Fredriksen, Hege-Beate; Rypdal, Martin; Rypdal, Kristoffer

    2016-04-01

    The Earth surface temperature responds to both dynamical and stochastic forcing on a myriad of temporal scales, and the high thermal inertia of the ocean is the major reason for the time-delayed responses to the forcing. To understand how the surface temperature can have decadal- to millennial-scale variability - also in the absence of deterministic external forcing - it is crucial to understand the slow physical processes acting to redistribute heat between the surface and the deeper ocean layers. We investigate how well the multiscale variability of the global sea surface temperature can be produced by a simple energy balance model, consisting of N vertically distributed boxes that exchange heat. In particular, we investigate the possibility of modeling the heat exchange in this N-box model using only linear terms. In addition, we investigate which criteria must be satisfied for this model to have a surface temperature that is well approximated by the observed scaling properties. Potential temperature data from all vertical ocean layers in some CMIP5 models are used to estimate the parameters in the N-box model. Once we know these, we also have an estimate for the response/Green's function for global sea surface temperature. Furthermore, we can estimate the expected temperature variations both in the case of purely stochastic forcing and with any deterministic forcing. We should however keep in mind that these model parameters are derived solely from complex climate models, so it is also necessary to test this N-box model against observation data in order to verify/reject it as a suitable model.

  9. 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

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

    NASA Astrophysics Data System (ADS)

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

    2007-05-01

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

  11. 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.

  12. 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.

  13. Vortex creep and the internal temperature of neutron stars - Linear and nonlinear response to a glitch

    NASA Technical Reports Server (NTRS)

    Alpar, M. A.; Cheng, K. S.; Pines, D.

    1989-01-01

    The dynamics of pinned superfluid in neutron stars is determined by the thermal 'creep' of vortices. Vortex creep can respond to changes in the rotation rate of the neutron star crust and provide the observed types of dynamical relaxation following pulsar glitches. It also gives rise to energy dissipation, which determines the thermal evolution of pulsars once the initial heat content has been radiated away. The different possible regimes of vortex creep are explored, and it is shown that the nature of the dynamical response of the pinned superfluid evolves with a pulsar's age. Younger pulsars display a linear regime, where the response is linear in the initial perturbation and is a simple exponential relaxation as a function of time. A nonliner response, with a characteristic nonlinear dependence on the initial perturbation, is responsible for energy dissipation and becomes the predominant mode of response as the pulsar ages. The transition from the linear to the nonlinear regime depends sensitively on the temperature of the neutron star interior. A preliminary review of existing postglitch observations is given within this general evolutionary framework.

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. Retrieving soil water contents from soil temperature measurements by using linear regression

    NASA Astrophysics Data System (ADS)

    Xu, Qin; Zhou, Binbin

    2003-11-01

    A simple linear regression method is developed to retrieve daily averaged soil water content from diurnal variations of soil temperature measured at three or more depths. The method is applied to Oklahoma Mesonet soil temperature data collected at the depths of 5, 10, and 30 cm during 11 20 June 1995. The retrieved bulk soil water contents are compared with direct measurements for one pair of nearly collocated Mesonet and ARM stations and also compared with the retrievals of a previous method at 14 enhanced Oklahoma Mesonet stations. The results show that the current method gives more persistent retrievals than the previous method. The method is also applied to Oklahoma Mesonet soil temperature data collected at the depths of 5, 25, 60, and 75 cm from the Norman site during 20 30 July 1998 and 1 31 July 2000. The retrieved soil water contents are verified by collocated soil water content measurements with rms differences smaller than the soil water observation error (0.05 m3 m-3). The retrievals are found to be moderately sensitive to random errors (±0.1 K) in the soil temperature observations and errors in the soil type specifications.

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. Seasonal and spatial heterogeneity of recent sea surface temperature trends in the Caribbean Sea and southeast Gulf of Mexico.

    PubMed

    Chollett, Iliana; Müller-Karger, Frank E; Heron, Scott F; Skirving, William; Mumby, Peter J

    2012-05-01

    Recent changes in ocean temperature have impacted marine ecosystem function globally. Nevertheless, the responses have depended upon the rate of change of temperature and the season when the changes occur, which are spatially variable. A rigorous statistical analysis of sea surface temperature observations over 25 years was used to examine spatial variability in overall and seasonal temperature trends within the wider Caribbean. The basin has experienced high spatial variability in rates of change of temperature. Most of the warming has been due to increases in summer rather than winter temperatures. However, warming was faster in winter in the Loop Current area and the south-eastern Caribbean, where the annual temperature ranges have contracted. Waters off Florida, Cuba and the Bahamas had a tendency towards cooling in winter, increasing the amplitude of annual temperature ranges. These detailed patterns can be used to elucidate ecological responses to climatic change in the region.

  6. Trends and periodicity of daily temperature and precipitation extremes during 1960-2013 in Hunan Province, central south China

    NASA Astrophysics Data System (ADS)

    Chen, Ajiao; He, Xinguang; Guan, Huade; Cai, Yi

    2017-02-01

    In this study, the trends and periodicity in climate extremes are examined in Hunan Province over the period 1960-2013 on the basis of 27 extreme climate indices calculated from daily temperature and precipitation records at 89 meteorological stations. The results show that in the whole province, temperature extremes exhibit a warming trend with more than 50% stations being statistically significant for 7 out of 16 temperature indices, and the nighttime temperature increases faster than the daytime temperature at the annual scale. The changes in most extreme temperature indices show strongly coherent spatial patterns. Moreover, the change rates of almost all temperature indices in north Hunan are greater than those of other regions. However, the statistically significant changes in indices of extreme precipitation are observed at fewer stations than in extreme temperature indices, forming less spatially coherent patterns. Positive trends in indices of extreme precipitation show that the amount and intensity of extreme precipitation events are generally increasing in both annual and seasonal scales, whereas the significant downward trend in consecutive wet days indicates that the precipitation becomes more even over the study period. Analysis of changes in probability distributions of extreme indices for 1960-1986 and 1987-2013 also demonstrates a remarkable shift toward warmer condition and increasing tendency in the amount and intensity of extreme precipitation during the past decades. The variations in extreme climate indices exhibit inconstant frequencies in the wavelet power spectrum. Among the 16 temperature indices, 2 of them show significant 1-year periodic oscillation and 7 of them exhibit significant 4-year cycle during some certain periods. However, significant periodic oscillations can be found in all of the precipitation indices. Wet-day precipitation and three absolute precipitation indices show significant 1-year cycle and other seven provide

  7. 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.

  8. 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.

  9. Modelling impacts of atmospheric deposition and temperature on long-term DOC trends.

    PubMed

    Sawicka, K; Rowe, E C; Evans, C D; Monteith, D T; E I Vanguelova; Wade, A J; J M Clark

    2017-02-01

    It is increasingly recognised that widespread and substantial increases in Dissolved organic carbon (DOC) concentrations in remote surface, and soil, waters in recent decades are linked to declining acid deposition. Effects of rising pH and declining ionic strength on DOC solubility have been proposed as potential dominant mechanisms. However, since DOC in these systems is derived mainly from recently-fixed carbon, and since organic matter decomposition rates are considered sensitive to temperature, uncertainty persists over the extent to which other drivers that could influence DOC production. Such potential drivers include fertilisation by nitrogen (N) and global warming. We therefore ran the dynamic soil chemistry model MADOC for a range of UK soils, for which time series data are available, to consider the likely relative importance of decreased deposition of sulphate and chloride, accumulation of reactive N, and higher temperatures, on soil DOC production in different soils. Modelled patterns of DOC change generally agreed favourably with measurements collated over 10-20years, but differed markedly between sites. While the acidifying effect of sulphur deposition appeared to be the predominant control on the observed soil water DOC trends in all the soils considered other than a blanket peat, the model suggested that over the long term, the effects of nitrogen deposition on N-limited soils may have been sufficient to raise the "acid recovery DOC baseline" significantly. In contrast, reductions in non-marine chloride deposition and effects of long term warming appeared to have been relatively unimportant. The suggestion that future DOC concentrations might exceed preindustrial levels as a consequence of nitrogen pollution has important implications for drinking water catchment management and the setting and pursuit of appropriate restoration targets, but findings still require validation from reliable centennial-scale proxy records, such as those being developed

  10. 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.

  11. 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.

  12. An Elimination Method of Temperature-Induced Linear Birefringence in a Stray Current Sensor

    PubMed Central

    Xu, Shaoyi; Li, Wei; Xing, Fangfang; Wang, Yuqiao; Wang, Ruilin; Wang, Xianghui

    2017-01-01

    In this work, an elimination method of the temperature-induced linear birefringence (TILB) in a stray current sensor is proposed using the cylindrical spiral fiber (CSF), which produces a large amount of circular birefringence to eliminate the TILB based on geometric rotation effect. First, the differential equations that indicate the polarization evolution of the CSF element are derived, and the output error model is built based on the Jones matrix calculus. Then, an accurate search method is proposed to obtain the key parameters of the CSF, including the length of the cylindrical silica rod and the number of the curve spirals. The optimized results are 302 mm and 11, respectively. Moreover, an effective factor is proposed to analyze the elimination of the TILB, which should be greater than 7.42 to achieve the output error requirement that is not greater than 0.5%. Finally, temperature experiments are conducted to verify the feasibility of the elimination method. The results indicate that the output error caused by the TILB can be controlled less than 0.43% based on this elimination method within the range from −20 °C to 40 °C. PMID:28282953

  13. 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.

  14. Linearized acoustic perturbation equations for low Mach number flow with variable density and temperature

    NASA Astrophysics Data System (ADS)

    Munz, Claus-Dieter; Dumbser, Michael; Roller, Sabine

    2007-05-01

    When the Mach number tends to zero the compressible Navier-Stokes equations converge to the incompressible Navier-Stokes equations, under the restrictions of constant density, constant temperature and no compression from the boundary. This is a singular limit in which the pressure of the compressible equations converges at leading order to a constant thermodynamic background pressure, while a hydrodynamic pressure term appears in the incompressible equations as a Lagrangian multiplier to establish the divergence-free condition for the velocity. In this paper we consider the more general case in which variable density, variable temperature and heat transfer are present, while the Mach number is small. We discuss first the limit equations for this case, when the Mach number tends to zero. The introduction of a pressure splitting into a thermodynamic and a hydrodynamic part allows the extension of numerical methods to the zero Mach number equations in these non-standard situations. The solution of these equations is then used as the state of expansion extending the expansion about incompressible flow proposed by Hardin and Pope [J.C. Hardin, D.S. Pope, An acoustic/viscous splitting technique for computational aeroacoustics, Theor. Comput. Fluid Dyn. 6 (1995) 323-340]. The resulting linearized equations state a mathematical model for the generation and propagation of acoustic waves in this more general low Mach number regime and may be used within a hybrid aeroacoustic approach.

  15. 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

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

    PubMed

    Lin, Yong; Franzke, Christian L E

    2015-08-11

    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.

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

    NASA Astrophysics Data System (ADS)

    Hilburn, K. A.; Shie, C.

    2011-12-01

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

  18. 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.

  19. 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.

  20. Statistical adjustment of simulated inter-annual variability in an investigation of short-term temperature trend distributions over Canada

    NASA Astrophysics Data System (ADS)

    Grenier, Patrick; Chaumont, Diane; de Elía, Ramón

    2015-04-01

    Plausible climate trajectories towards warmer temperatures are made up of a succession of positive and negative short-term trends. Cooling trends over short durations (~ 5 to 25 years) are thus to be expected, and related probabilities have to rely on simulations from physically-based climate models. However, because simulations often present offsets in many statistical properties relative to observations, it is important to address the issue of statistical adjustment prior to characterizing expected short-term trend distributions. In this paper, we discuss the impact of statistically adjusting inter-annual variability on short-term cooling probability for locations across Canada and during the current period (2006-2035). Two methods are considered, one that uses a transfer function based on the dissimilarity between simulated and observed detrended annual temperature values (residuals) during a calibration period, and another that uses an autoregressive model of the observational residuals for generating variability. Long-term trends remain invariant in both methods. Results show that although short-term trends in individual simulations are in some cases highly impacted, cooling probabilities based on a multi-model ensemble are only slightly altered by each of the two methods, due to compensational effects. In summary, this paper presents an application where final results are robust to how simulated inter-annual variability is handled.

  1. 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.

  2. NW-trending linear gravity and magnetic features: Plate tectonics implications for the western Gulf of Mexico

    SciTech Connect

    Heyn, T.; Jones, S. )

    1993-02-01

    Gravity and magnetic maps have been interpreted and integrated with geological observations to investigate the linkage between deep sub-salt basement and shallow structures imaged seismically in the Mesozoic-Cenozoic marine section of southeast Texas. Shallow structures could have been inherited from sub-salt basement; e.g. shallow anticlines imaged below a detachment which approximately corresponds with the top of the Wilcox Formation may occur above basement highs. The sub-detachment anticlines probably occur where salt thickness variations mimic the syn-rifting topography. These anticlines formed when autochthonous salt withdrew and the Mesozoic-Cenozoic marine section was draped over sub-salt basement horsts. Salt probably accumulated due to thermal subsidence after rifting, and may partly have infilled some rift basins. Balanced cross-sections indicate that salt withdraw persisted until the Late Oligocene. The interpretation is based on the identification of NW-trending lineaments or alignments of magnetic and gravity anomalies. Lineaments are interpreted as rift-related transfer zones in sub-salt basement because (i) refraction data shot perpendicular to the lineaments indicates that basement relief has a NW -trending alignment, (ii) lineaments parallel the San Marcos Arch, (iii) lineaments occur in the same location on both gravity and magnetic maps, and (iv) transfer zones of Mesozoic graben systems penetrated onshore are NW-trending. NW-trending lineaments do not fan and have a very long radius of curvature; this suggests that the pole of rotation for the early opening of the Gulf of Mexico is located many thousands of kilometers to the northeast or southwest.

  3. Long-term trend and multi-annual variability of water temperature in the pristine Bela River basin (Slovakia)

    NASA Astrophysics Data System (ADS)

    Pekárová, Pavla; Miklánek, Pavol; Halmová, Dana; Onderka, Milan; Pekár, Ján; Kučárová, Katarína; Liová, Soňa; Škoda, Peter

    2011-04-01

    SummaryBiological processes in surface waters appreciably depend on temperature of water. This paper summarizes our investigations of water temperature in the Bela River. The Bela River is a mountainous stream not influenced by direct human activities, draining the headwaters of the Vah River basin in the Tatra National Park (TANAP), Slovakia. Our primary aim was to identify the long-term trends and multi-annual variability of the annual water temperature at the Podbanske gauging station, using temperature readings taken at 7.00 am for the period of 50 years (1959-2008). Long-term mean of the annual water temperature of the Bela River at the Podbanske gauging station (922 m a.s.l.) was 4.2 °C, the air temperature at Podbanske meteorological station (972 m a.s.l.) was 5.0 °C. Both, air and water temperature, show an increasing trend. While the air temperature within 50-years increased significantly by 1.5 °C, in the case of water temperature this increase was merely by 0.12 °C. On November 19, 2004, a wind-throw brushed the investigated area with an aftermath of 15.4% destroyed forest in the Bela basin, mainly along the area adjacent to the river. Therefore, in the second part of the study, the impact of the riparian vegetation growing along the river banks was evaluated for two distinctive periods, i.e. the period prior and after the wind-throw. We statistically analysed the changes in water temperature on 6-year time series of daily water temperature (November 2001 through November 2007). The results presented herein may be useful for defining boundary values for surface water temperature, as required by the EC Water Framework Directive.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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.

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

    DOE PAGES

    Grotjahn, Richard; Black, Robert; Leung, Ruby; ...

    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

  11. 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

  12. The influence of elevation, latitude and Arctic Oscillation on trends in temperature extremes over northeastern China, 1961-2011

    NASA Astrophysics Data System (ADS)

    Zeng, Wei; Yu, Zhen; Li, Xilin

    2017-02-01

    Trend magnitudes of 14 indices of temperature extremes at 70 stations with elevations, latitude and Arctic Oscillation over northeast China during 1960-2011 are examined. There are no significant correlations between elevation and trend magnitudes with the exception of TXn (Min T max), TNn (Min T min), TR20 (tropical nights) and GSL (growing season length). Analysis of trend magnitudes by topographic type has a strong influence, which overrides that of degree of urbanization. By contrast, most of the temperature indices have stronger correlations with the latitude and Arctic Oscillation index. The correlations between the Arctic Oscillation index and percentile indices, including TX10p (cool days), TX90p (warm days), TN10p (cool nights), TN90p (warm nights), are not the same in different areas. To summarize, analysis of trend magnitudes by topographic type, the latitude and the Arctic Oscillation shows three factors to have a strong influence in this dataset, which overrides that of elevation and degree of urbanization.

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

    DTIC Science & Technology

    2007-07-01

    atmosphere is paramount to our understanding of climate change . The Microwave Sounding Unit (MSU) derived atmospheric temperature trends are used in...that must continue to be addressed as they are used for climate change studies [Mears and Wentz, 2005]. Additionally, the accuracy of methods that...a thorough examination of these data and methods using these data is necessary to insure long-term stability as required for climate change studies

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

    NASA Astrophysics Data System (ADS)

    Wilt, Thomas Edmund

    The use of composite materials in aerospace applications, particularly engine components, is becoming more prevalent due to the materials high strength, yet low weight. In addition to thermomechanical deformation response, life prediction and damage modeling analysis is also required to assess the component's service life. These complex and computationally intensive analyses require the development of simple, efficient and robust finite element analysis capabilities. A simple robust finite element which can effectively model the multi-layer 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 will also be 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. Also, the element appears to be relatively insensitive to mesh distortions. The robustness and efficiency of the fully implicit integration algorithms is effectively demonstrated in the numerical results. That is, large time steps and a significant reduction in global iterations, as a direct result of utilizing the consistent tangent matrices, is shown.

  15. 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.

  16. Stratospheric Temperature Trends in the 11 Years of AIRS Spectral Radiance Observations

    NASA Astrophysics Data System (ADS)

    Pan, F.; Huang, X.; Chen, X.; Guo, H.

    2014-12-01

    The AIRS (Atmospheric Infrared Sounder) level-1b radiances have been shown to be well calibrated (~0.3K or higher) and have little secular drift (~4mK/year) since its operation started in 2002. Given the rich information contained in the spectral radiances, such impressive instrument performances make AIRS radiances a valuable data set in the study of stratospheric climate. We compile 11 years (Sep 2002- Aug 2013) of AIRS radiances at channels in the CO2 v2 band with weighting functions peaked in the stratosphere. Using a state-of-the-art fast and accurate radiance simulator based on the PCRTM (Principle Component-based Radiative Transfer Model), we also simulate synthetic AIRS radiances at these channels based on two types of inputs: one is simulations by a free-running GFDL AM3 model and the other is ECMWF ERA-interim reanalysis. AIRS lower-stratospheric channels indicate a cooling trend of no more than 0.23 K/decade while its middle-stratospheric channels show a statistically significant cooling trend as large as 0.58 K/decade. Compared with AIRS observations, GFDL AM3 simulations underestimate the cooling trends in the middle-stratospheric channels while overestimate in the lower-stratospheric channels. Further simulations with separately varying CO2 and SST suggest that the change of CO2 alone is responsible for majority of the cooling trend in the middle-stratospheric channels, but the contributions of time-varying CO2 and SST are comparable in the lower-stratospheric channels. In contrast, the synthetic radiances based on ERA-interim reanalysis show statistically significant positive trends in virtually all stratospheric channels. We also compare the zonal-mean trends estimated from observed and synthetic AIRS spectral radiances and climate data records based on multi-decade SSU (Stratospheric Sounding Unit) measurements. Though discrepancies exist in terms of magnitude and seasonality of the cooling, they all show that most cooling occurs in the tropics

  17. 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

  18. Taking the temperature of the world's lakes: Decadal variability and long-term trends in lake surface temperature from in situ and satellite observations

    NASA Astrophysics Data System (ADS)

    Lenters, John; Hook, Simon; Read, Jordan; Gray, Derek; Hampton, Stephanie; McIntyre, Peter; O'Reilly, Catherine; Schneider, Philipp; Sharma, Sapna; Contributors, Gltc

    2016-04-01

    Recent studies have shown significant warming of inland water bodies throughout the world. To better understand the patterns, mechanisms, and ecological implications of global lake warming, an initiative known as the "Global Lake Temperature Collaboration" (GLTC) was started in 2010, with the objective of compiling and analyzing lake temperature data from numerous satellite and in situ records dating back at least 20-30 years. The GLTC project has now assembled data from over 250 lakes, with some in situ records dating back more than 100 years. Here, we present an analysis of the long-term warming trends, decadal variability, and a direct comparison between in situ and remotely sensed summer lake surface temperatures from 1895-2009. The results show consistent trends of increasing summer-mean lake surface temperature across most but not all sites. Lakes with especially long records show accelerated warming in the most recent two to three decades, with almost half of the lakes warming at rates in excess of 0.5 °C per decade during the period 1985-2009, and a few even exceeding 1.0 °C per decade.

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

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

    SciTech Connect

    Maruca, Bennett A.; Kasper, Justin C.; Gary, S. Peter

    2012-04-01

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

  1. 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...

  2. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

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

  4. Long-term patterns of air temperatures, daily temperature range, precipitation, grass-reference evapotranspiration and aridity index in the USA great plains: Part II. Temporal trends

    NASA Astrophysics Data System (ADS)

    Kukal, M.; Irmak, S.

    2016-11-01

    Detection of long-term changes in climate variables over large spatial scales is a very important prerequisite to the development of effective mitigation and adaptation measures for the future potential climate change and for developing strategies for future hydrologic balance analyses under changing climate. Moreover, there is a need for effective approaches of providing information about these changes to decision makers, water managers and stakeholders to aid in efficient implementation of the developed strategies. This study involves computation, mapping and analyses of long-term (1968-2013) county-specific trends in annual, growing-season (1st May-30th September) and monthly air temperatures [(maximum (Tmax), minimum (Tmin) and average (Tavg)], daily temperature range (DTR), precipitation, grass reference evapotranspiration (ETo) and aridity index (AI) over the USA Great Plains region using datasets from over 800 weather station sites. Positive trends in annual Tavg, Tmax and Tmin, DTR, precipitation, ETo and AI were observed in 71%, 89%, 85%, 31%, 61%, 38% and 66% of the counties in the region, respectively, whereas these proportions were 48%, 89%, 62%, 20%, 57%, 28%, and 63%, respectively, for the growing-season averages of the same variables. On a regional average basis, the positive trends in growing-season Tavg, Tmax and Tmin, DTR, precipitation, ETo and AI were 0.18 °C decade-1, 0.19 °C decade-1, 0.17 °C decade-1, 0.09 °C decade-1, 1.12 mm yr-1, 0.4 mm yr-1 and 0.02 decade-1, respectively, and the negative trends were 0.21 °C decade-1, 0.06 °C decade-1, 0.09 °C decade-1, 0.22 °C decade-1, 1.16 mm yr-1, 0.76 mm yr-1 and 0.02 decade-1, respectively. The temporal trends were highly variable in space and were appropriately represented using monthly, annual and growing-season maps developed using Geographic Information System (GIS) techniques. The long-term and spatial and temporal information and data for a large region provided in this study can be

  5. Temperature Trends in Coal Char Combustion under Oxy-fuel Conditions for the Determination of Kinetics

    SciTech Connect

    Iqbal, Samira; Hecht, Ethan

    2014-08-01

    Oxy-fuel combustion technology with carbon capture and storage could significantly reduce global CO2 emissions, a greenhouse gas. Implementation can be aided by computational fluid dynamics (CFD) simulations, which require an accurate understanding of coal particle kinetics as they go through combustion in a range of environments. To understand the kinetics of pulverized coal char combustion, a heated flow reactor was operated under a wide range of experimental conditions. We varied the environment for combustion by modifying the diluent gas, oxygen concentration, gas flow rate, and temperature of the reactor/reacting gases. Measurements of reacting particle temperatures were made for a sub-bituminous and bituminous coal char, in environments with CO2 or N2 as the diluent gas, with 12, 24, and 36 vol-% oxygen concentration, at 50, 80, 100, and 200 standard liters per minute flowing through the reactor, reactor temperatures of 1200, 1400 K, at pressures slightly above atmospheric. The data shows consistent increasing particle temperature with increased oxygen concentration, reactor temperature and higher particle temperatures for N2 diluent than CO2. We also see the effects of CO2 gasification when different ranks of coal are used, and how the reduction in the temperature due to the CO2 diluent is greater for the coal char that has higher reactivity. Quantitative measurements for temperature are not yet complete due to ongoing calibration of detection systems.

  6. 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.

  7. 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.

  8. Theoretical prediction of electrocaloric effect based on non-linear behaviors of dielectric permittivity under temperature and electric fields

    NASA Astrophysics Data System (ADS)

    Liu, Hongbo; Yang, Xue

    2015-11-01

    The electrocaloric (EC) effect has been paid great attentions recently for applications on cooling or electricity generation. However, the directly commercial measurement equipment for the effect is still unavailable. Here we report a novel method to predict EC effect by non-linear behaviors of dielectric permittivity under temperature and electric fields. According to the method, the analytical equations of EC temperature change ΔT are directly given for normal ferroelectrics and relaxor. The calculations have been performed on several materials and it is shown that the method is suitable for both inorganic and organic ferroelectrics, and relaxor.

  9. Climate trends in northern Ontario and Québec from borehole temperature profiles

    NASA Astrophysics Data System (ADS)

    Pickler, Carolyne; Beltrami, Hugo; Mareschal, Jean-Claude

    2016-12-01

    The ground surface temperature histories of the past 500 years were reconstructed at 10 sites containing 18 boreholes in northeastern Canada. The boreholes, between 400 and 800 m deep, are located north of 51° N and west and east of James Bay in northern Ontario and Québec. We find that both sides of James Bay have experienced similar ground surface temperature histories with a warming of 1.51 ± 0.76 K during the period of 1850 to 2000, similar to borehole reconstructions for the southern portion of the Superior Province and in agreement with available proxy data. A cooling period corresponding to the Little Ice Age was found at only one site. Despite permafrost maps locating the sites in a region of discontinuous permafrost, the ground surface temperature histories suggest that the potential for permafrost was minimal to absent over the past 500 years. This could be the result of air surface temperature interpolation used in permafrost models being unsuitable to account for the spatial variability of ground temperatures along with an offset between ground and air surface temperatures due to the snow cover.

  10. 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.

  11. Piezoelectric Non-linear Nanomechanical Temperature and Acceleration Intensive Clocks (PENNTAC)

    DTIC Science & Technology

    2014-05-01

    13 Figure 15: Microcontroller based...final temperature stability of < 2 ppm from – 40 to + 85 °C was demonstrated for a microcontroller -based ovenized oscillator. Fundamental limits...the resonator center frequency is programmed to be at a particular frequency at a given temperature by storing in the microcontroller the amount of

  12. 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.

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

    NASA Astrophysics Data System (ADS)

    Slominska, Ewa; Rothkaehl, Hanna

    2013-07-01

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

  14. 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.

  15. 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

  16. 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

  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. 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.

    2016-11-01

    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.

  19. 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.

  20. 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.

  1. 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

  2. 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…

  3. Spatial and temporal variability in minimum temperature trends in the western U.S. sagebrush steppe

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Climate is a major driver of ecosystem dynamics. In recent years there has been considerable interest in future climate change and potential impacts on ecosystems and management options. In this paper, we analyzed minimum monthly temperature (T min) for ten rural locations in the western sagebrush...

  4. An Inter-comparison of Three Heat Wave Types in China during 1961–2010: Observed Basic Features and Linear Trends

    PubMed Central

    Chen, Yang; Li, Yi

    2017-01-01

    Using observed daily temperatures in China, three independent types of heat waves (HWs), including daytime HWs, nighttime HWs, and compound HWs (with both extreme daily maxima and minima), were defined. Different types of HWs showed distinctive preferences in occurrence locations and timing. However, spatial patterns of accompanying relative humidity were generally independent of categorization, except for closer association of nighttime events with high humidity level. Compound HWs and nighttime HWs experienced significant increases in frequency, participating days, mean duration, intensity and areal extent. Conversely, significant decreasing trends of above indicators prevailed in daytime HWs, especially in central-eastern China. Tendency of relative humidity changes didn’t vary with HW types. Instead it caused an interesting phenomenon that dry HWs in the west became more humid and humid events in the east got dryer, as manifested most obviously in compound type. Thorough comparisons highlight the evolutionary dominance of HW types. Specifically, previously-dominating independent daytime HWs have been increasingly replaced by independent nighttime events in central-eastern China, and by compound HWs in southern China. That’s the very reason for negative trends of independent daytime HWs in eastern China, even in a warming climate. PMID:28361892

  5. An Inter-comparison of Three Heat Wave Types in China during 1961-2010: Observed Basic Features and Linear Trends.

    PubMed

    Chen, Yang; Li, Yi

    2017-03-31

    Using observed daily temperatures in China, three independent types of heat waves (HWs), including daytime HWs, nighttime HWs, and compound HWs (with both extreme daily maxima and minima), were defined. Different types of HWs showed distinctive preferences in occurrence locations and timing. However, spatial patterns of accompanying relative humidity were generally independent of categorization, except for closer association of nighttime events with high humidity level. Compound HWs and nighttime HWs experienced significant increases in frequency, participating days, mean duration, intensity and areal extent. Conversely, significant decreasing trends of above indicators prevailed in daytime HWs, especially in central-eastern China. Tendency of relative humidity changes didn't vary with HW types. Instead it caused an interesting phenomenon that dry HWs in the west became more humid and humid events in the east got dryer, as manifested most obviously in compound type. Thorough comparisons highlight the evolutionary dominance of HW types. Specifically, previously-dominating independent daytime HWs have been increasingly replaced by independent nighttime events in central-eastern China, and by compound HWs in southern China. That's the very reason for negative trends of independent daytime HWs in eastern China, even in a warming climate.

  6. Geophysical trends from 12+ years of AIRS radiance trends

    NASA Astrophysics Data System (ADS)

    DeSouza-Machado, Sergio; Strow, Larrabee; Tangborn, Andrew; Hepplewhite, Chris; Motteler, Howard; Schou, Paul; Buczkowski, Steve

    2015-04-01

    NASA's Atmospheric Infrared Sounder has daily been providing low noise, stable top-of-the atmosphere hyperspectral radiances since 2002. Here we present analysis from 12 year linear radiance trends obtained from two AIRS radiance subsets : (1) clear-sky scenes over ocean and (2) all-sky scenes along the nadir track, which are used to retrieve a geophysical trends using an optimal estimation approach. The retrieved clear sky trends compare favorably with ERA and MERRA re-analysis trends, and in-situ trends for the minor gases. Analysis of all-sky trends show they agree better with ERA than either MERRA or the AIRS Level-2 retrievals. The radiance trends provide highly accurate measurements of atmospheric variability with easily understood error characteristics, unlike typical Level 2 retrievals. These approaches should provide highly accurate measurements of a variety of climate trends (temperature and humidity profiles, land surface temperature, cloud radiative forcing) as the AIRS (or AIRS + JPSS/CrIS + IASI) instrument time-series extends to 15+ years.

  7. Long-term patterns of air temperatures, daily temperature range, precipitation, grass-reference evapotranspiration and aridity index in the USA Great Plains: Part I. Spatial trends

    NASA Astrophysics Data System (ADS)

    Kukal, M.; Irmak, S.

    2016-11-01

    Due to their substantial spatio-temporal behavior, long-term quantification and analyses of important hydrological variables are essential for practical applications in water resources planning, evaluating the water use of agricultural crop production and quantifying crop evapotranspiration patterns and irrigation management vs. hydrologic balance relationships. Observed data at over 800 sites across the Great Plains of USA, comprising of 9 states and 2,307,410 km2 of surface area, which is about 30% of the terrestrial area of the USA, were used to quantify and map large-scale and long-term (1968-2013) spatial trends of air temperatures, daily temperature range (DTR), precipitation, grass-reference evapotranspiration (ETo) and aridity index (AI) at monthly, growing season and annual time steps. Air temperatures had a strong north to south increasing trend, with annual average varying from -1 to 24 °C, and growing season average temperature varying from 8 to 30 °C. DTR gradually decreased from western to eastern parts of the region, with a regional annual and growing season averages of 14.25 °C and 14.79 °C, respectively. Precipitation had a gradual shift towards higher magnitudes from west to east, with the average annual and growing season (May-September) precipitation ranging from 163 to 1486 mm and from 98 to 746 mm, respectively. ETo had a southwest-northeast decreasing trend, with regional annual and growing season averages of 1297 mm and 823 mm, respectively. AI increased from west to east, indicating higher humidity (less arid) towards the east, with regional annual and growing season averages of 0.49 and 0.44, respectively. The spatial datasets and maps for these important climate variables can serve as valuable background for climate change and hydrologic studies in the Great Plains region. Through identification of priority areas from the developed maps, efforts of the concerned personnel and agencies and resources can be diverted towards development

  8. Two-temperature synthesis of non-linear optical compound CdGeAs2

    NASA Astrophysics Data System (ADS)

    Zhu, Chongqiang; Verozubova, G. A.; Mironov, Yuri P.; Lei, Zuotao; Song, Liangcheng; Ma, Tianhui; Okunev, A. O.; Yang, Chunhui

    2016-12-01

    In this work, we report on a new approach to synthesize large-scale nonlinear optical chalcopyrite compound CdGeAs2 (cadmium germanium arsenide), in which the arsenic (As) precursor and the mixture of the cadmium (Cd) and the germanium (Ge) were separated in two distinct temperature-defined zones of a furnace. Through probing the intermediate product prepared at pre-set temperature points of hot-zone area, it was revealed that the ternary compound CdGeAs2 was formed through chemical reactions among Cd3As2, CdAs2, GeAs, GeAs2 and Ge. A new intermediate crystalline compound, with determined crystal parameter c=0.9139 nm and unknown a parameter, was identified when the temperature of the mixture of Cd and Ge was set to 680 °C, which, however, disappeared when the temperature was set to 770 °C, yielding pure CdGeAs2 product. Most likely, the identified new intermediate compound has layered graphite-like structure. Moreover, we show that the described two-temperature synthesis method allows us to produce near 250 g CdGeAs2 product during one run in a horizontal furnace and 500 g in a tilted horizontal furnace with rotated reactor.

  9. Variability in solar radiation and temperature explains observed patterns and trends in tree growth rates across four tropical forests.

    PubMed

    Dong, Shirley Xiaobi; Davies, Stuart J; Ashton, Peter S; Bunyavejchewin, Sarayudh; Supardi, M N Nur; Kassim, Abd Rahman; Tan, Sylvester; Moorcroft, Paul R

    2012-10-07

    The response of tropical forests to global climate variability and change remains poorly understood. Results from long-term studies of permanent forest plots have reported different, and in some cases opposing trends in tropical forest dynamics. In this study, we examined changes in tree growth rates at four long-term permanent tropical forest research plots in relation to variation in solar radiation, temperature and precipitation. Temporal variation in the stand-level growth rates measured at five-year intervals was found to be positively correlated with variation in incoming solar radiation and negatively related to temporal variation in night-time temperatures. Taken alone, neither solar radiation variability nor the effects of night-time temperatures can account for the observed temporal variation in tree growth rates across sites, but when considered together, these two climate variables account for most of the observed temporal variability in tree growth rates. Further analysis indicates that the stand-level response is primarily driven by the responses of smaller-sized trees (less than 20 cm in diameter). The combined temperature and radiation responses identified in this study provide a potential explanation for the conflicting patterns in tree growth rates found in previous studies.

  10. 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.

  11. 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.

  12. Linear FBG Temperature Sensor Interrogation with Fabry-Perot ITU Multi-wavelength Reference.

    PubMed

    Park, Hyoung-Jun; Song, Minho

    2008-10-29

    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.

  13. 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. PMID:27873898

  14. Observed trends in indices of daily and extreme temperature and precipitation for the countries of the western Indian Ocean, 1961-2008

    NASA Astrophysics Data System (ADS)

    Vincent, L. A.; Aguilar, E.; Saindou, M.; Hassane, A. F.; Jumaux, G.; Roy, D.; Booneeady, P.; Virasami, R.; Randriamarolaza, L. Y. A.; Faniriantsoa, F. R.; Amelie, V.; Seeward, H.; Montfraix, B.

    2011-05-01

    A workshop on climate change indices was held at the Mauritius Meteorological Services in October 2009 to produce the first analysis of climate trends for the countries of the western Indian Ocean. Scientists brought their long-term daily temperature and precipitation for a careful assessment of data quality and homogeneity, and for the preparation of climate change indices. This paper reports on the trends in daily and extreme temperature and precipitation indices for 1961-2008. The results indicate a definitive warming of surface air temperature at land stations. Annual means of the daytime and nighttime temperatures have increased at a similar rate, leading to no discernible change in the diurnal temperature range. Significant increasing trends were found in the frequency of warm days and warm nights, while decreasing trends were observed in the frequency of cold days and cold nights. Moreover, it seems that the warm extremes have changed more than the cold extremes in the western Indian Ocean region. Trends in precipitation indices are generally weak and show less spatial coherence. Regionally, a significant decrease was found in the annual total rainfall for the past 48 years. The results also show some increase in consecutive dry days, no change in daily intensity and consecutive wet days, and a decrease in extreme precipitation events. Temperature indices are highly correlated with sea surface temperatures of the region, whereas weak correlations are found with the precipitation indices.

  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. 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.

  17. 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

  18. 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

  19. Contribution of Changes in Sea Surface Temperature and Aerosol Loading to the Decreasing Precipitation Trend in Southern China.

    NASA Astrophysics Data System (ADS)

    Cheng, Yanjie; Lohmann, Ulrike; Zhang, Junhua; Luo, Yunfeng; Liu, Zuoting; Lesins, Glen

    2005-05-01

    The effects of increasing sea surface temperature (SST) and aerosol loading in a drought region in Southern China are studied using aerosol optical depth (AOD), low-level cloud cover (LCC), visibility, and precipitation from observed surface data; wind, temperature, specific humidity, and geopotential height from the NCEP-NCAR reanalysis fields; and SST from the NOAA archive data. The results show a warming of the SST in the South China Sea and the Indian Ocean, and a strengthening of the West Pacific Subtropical High (WPSH) in the early summer during the last 40 yr, with the high pressure system extending farther westward over the continent in Southern China. Because the early summer average temperature contrast between the land and ocean decreased, the southwesterly monsoon from the ocean onto mainland China weakened and a surface horizontal wind divergence anomaly occurred over Southern China stabilizing the boundary layer. Thus, less moisture was transported to Southern China, causing a drying trend. Despite this, surface observations show that AOD and LCC have increased, while visibility has decreased. Precipitation has decreased in this region in the early summer, consistent with both the second aerosol indirect effect (reduction in precipitation efficiency caused by the more numerous and smaller cloud droplets) and dynamically induced changes from convective to more stratiform clouds. The second aerosol indirect effect and increases in SST and greenhouse gases (GHG) were simulated separately with the ECHAM4 general circulation model (GCM). The GCM results suggest that both effects contribute to the changes in LCC and precipitation in the drought region in Southern China. The flooding trend in Eastern China, however, is more likely caused by strengthened convective precipitation associated with increases in SST and GHG.

  20. 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.

  1. 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.

  2. 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

  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. Linear topology in amorphous metal oxide electrochromic networks obtained via low-temperature solution processing

    NASA Astrophysics Data System (ADS)

    Llordés, Anna; Wang, Yang; Fernandez-Martinez, Alejandro; Xiao, Penghao; Lee, Tom; Poulain, Agnieszka; Zandi, Omid; Saez Cabezas, Camila A.; Henkelman, Graeme; Milliron, Delia J.

    2016-12-01

    Amorphous transition metal oxides are recognized as leading candidates for electrochromic window coatings that can dynamically modulate solar irradiation and improve building energy efficiency. However, their thin films are normally prepared by energy-intensive sputtering techniques or high-temperature solution methods, which increase manufacturing cost and complexity. Here, we report on a room-temperature solution process to fabricate electrochromic films of niobium oxide glass (NbOx) and `nanocrystal-in-glass’ composites (that is, tin-doped indium oxide (ITO) nanocrystals embedded in NbOx glass) via acid-catalysed condensation of polyniobate clusters. A combination of X-ray scattering and spectroscopic characterization with complementary simulations reveals that this strategy leads to a unique one-dimensional chain-like NbOx structure, which significantly enhances the electrochromic performance, compared to a typical three-dimensional NbOx network obtained from conventional high-temperature thermal processing. In addition, we show how self-assembled ITO-in-NbOx composite films can be successfully integrated into high-performance flexible electrochromic devices.

  5. Linear topology in amorphous metal oxide electrochromic networks obtained via low-temperature solution processing.

    PubMed

    Llordés, Anna; Wang, Yang; Fernandez-Martinez, Alejandro; Xiao, Penghao; Lee, Tom; Poulain, Agnieszka; Zandi, Omid; Saez Cabezas, Camila A; Henkelman, Graeme; Milliron, Delia J

    2016-12-01

    Amorphous transition metal oxides are recognized as leading candidates for electrochromic window coatings that can dynamically modulate solar irradiation and improve building energy efficiency. However, their thin films are normally prepared by energy-intensive sputtering techniques or high-temperature solution methods, which increase manufacturing cost and complexity. Here, we report on a room-temperature solution process to fabricate electrochromic films of niobium oxide glass (NbOx) and 'nanocrystal-in-glass' composites (that is, tin-doped indium oxide (ITO) nanocrystals embedded in NbOx glass) via acid-catalysed condensation of polyniobate clusters. A combination of X-ray scattering and spectroscopic characterization with complementary simulations reveals that this strategy leads to a unique one-dimensional chain-like NbOx structure, which significantly enhances the electrochromic performance, compared to a typical three-dimensional NbOx network obtained from conventional high-temperature thermal processing. In addition, we show how self-assembled ITO-in-NbOx composite films can be successfully integrated into high-performance flexible electrochromic devices.

  6. 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).

  7. Time Trends and Predictors of Abnormal Postoperative Body Temperature in Infants Transported to the Intensive Care Unit

    PubMed Central

    Lyden, Angela K.; Benedict, Wendy L.; Ramachandran, Satya Krishna

    2016-01-01

    Background. Despite increasing adoption of active warming methods over the recent years, little is known about the effectiveness of these interventions on the occurrence of abnormal postoperative temperatures in sick infants. Methods. Preoperative and postoperative temperature readings, patient characteristics, and procedural factors of critically ill infants at a single institution were retrieved retrospectively from June 2006 until May 2014. The primary endpoints were the incidence and trend of postoperative hypothermia and hyperthermia on arrival at the intensive care units. Univariate and adjusted analyses were performed to identify factors independently associated with abnormal postoperative temperatures. Results. 2,350 cases were included. 82% were normothermic postoperatively, while hypothermia and hyperthermia each occurred in 9% of cases. During the study period, hypothermia decreased from 24% to 2% (p < 0.0001) while hyperthermia remained unchanged (13% in 2006, 8% in 2014, p = 0.357). Factors independently associated with hypothermia were higher ASA status (p = 0.02), lack of intraoperative convective warming (p < 0.001) and procedure date before 2010 (p < 0.001). Independent associations for postoperative hyperthermia included lower body weight (p = 0.01) and procedure date before 2010 (p < 0.001). Conclusions. We report an increase in postoperative normothermia rates in critically ill infants from 2006 until 2014. Careful monitoring to avoid overcorrection and hyperthermia is recommended. PMID:27777585

  8. 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.

  9. 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.

  10. 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.

  11. Combined coherent anti-Stokes Raman spectroscopy and linear Raman spectroscopy for simultaneous temperature and multiple species measurements.

    PubMed

    Weikl, Markus C; Beyrau, Frank; Kiefer, Johannes; Seeger, Thomas; Leipertz, Alfred

    2006-06-15

    The simultaneous application of pure rotational coherent anti-Stokes Raman spectroscopy (CARS) and vibrational linear Raman spectroscopy (LRS) for the measurement of temperature and species concentrations in combustion systems is demonstrated. In addition to the standard rotational CARS experimental setup, only one detection system (spectrometer and intensified CCD camera) for the collection of the LRS signals was applied. The emission of the broadband dye laser used for CARS was shifted to the deep red to avoid interferences with the LRS signals located in the visible region. First experimental results from a vaporizing propane spray using an engine injection system are shown.

  12. Trends in persistent seasonal-scale atmospheric circulation patterns responsible for precipitation and temperature extremes in California

    NASA Astrophysics Data System (ADS)

    Swain, D. L.; Horton, D. E.; Singh, D.; Diffenbaugh, N. S.

    2015-12-01

    Long-lived anomalous atmospheric circulation patterns are often associated with surface weather extremes. This is particularly true from a hydroclimatic perspective in regions that have well-defined "wet seasons," where atmospheric anomalies that persist on a seasonal scale can lead to drought or (conversely) increase the risk of flood. Recent evidence suggests that both natural variability and global warming may be responsible for spatially and temporally heterogeneous changes in Northern Hemisphere atmospheric conditions over the past several decades. In this investigation, we assess observed trends in cool-season (Oct-May) circulation patterns over the northeastern Pacific Ocean which have historically been associated with precipitation and temperature extremes in California. We find that the occurrence of certain extreme seasonal-scale atmospheric configurations has changed substantially over the 1948-2015 period, and also that there has been a trend towards amplification of the cool-season mean state in this region. Notably, patterns similar to the persistent anticyclone associated with the extremely warm and dry conditions experienced during the ongoing 2012-2015 California drought occur more frequently in the second half of the observed record. This finding highlights the importance of examining changes in extreme and/or persistent atmospheric circulation configurations, which may exhibit different responses to natural and anthropogenic forcings than the mean state.

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

    PubMed

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

    2012-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

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

    PubMed

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

    2013-01-01

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

  16. Weather Type classification over Chile; patterns, trends, and impact in precipitation and temperature

    NASA Astrophysics Data System (ADS)

    Frias, T.; Trigo, R. M.; Garreaud, R.

    2009-04-01

    The Andes Cordillera induces considerable disturbances on the structure and evolution of the pressure systems that influences South America. Different weather types for southern South America are derived from the daily maps of geopotential height at 850hPa corresponding to a 42 year period, spanning from 1958 to 2000. Here we have used the ECWMF ERA-40 reanalysis dataset to construct an automated version of the Lamb Weather type (WTs) classification scheme (Jones et al., 1993) developed for the UK. We have identified 8 basic WTs (Cyclonic, Anticyclonic and 6 main directional types) following a similar methodology to that previously adopted by Trigo and DaCamara, 2000 (for Iberia). This classification was applied to two regions of study (CLnorth and CLsouth) which differ 20° in latitude, so that the vast Chile territory could be covered. Then were assessed the impact of the occurrence of this weather types in precipitation in Chile, as well as in the distribution of precipitation and temperature fields (reanalysis data) in southern half of South America. The results allow to conclude that the precipitation in central region of Chile is largely linked with the class occurrence (concerning CLnorth) of cyclonic circulation and of West quadrant (SW, W and NW), despite of it's relatively low frequency. In CLsouth, for its part, it is verified that the most frequent circulation is from the west quadrant, although the associated amount of rainfall is lower than in CLnorth. There was also a general decrease of precipitation at local weather stations chosen in the considered period of study, particularly in austral winter.

  17. 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.

  18. Future Trends in Extreme Temperatures over the Western U.S.: The Influence of Terrain and Coastlines

    NASA Astrophysics Data System (ADS)

    Brewer, M.

    2015-12-01

    A number of studies have suggested that heat waves will increase in frequency, intensity, and duration under anthropogenic global warming. However, these trends are less understood in regions of complex terrain or in coastal regions where temperature gradients are relatively larger and mesoscale features are important. Thus it is important to understand the regional impacts of terrain and land/water contrasts on heat extremes in a warming world, and identify changes in the conditions that drive such extremes. The northwest U.S. is a region with such surface complexity, where regional heat extremes arise from synoptic/mesoscale interactions between the large-scale flow and local topography This talk will analyze changes to the synoptic and mesoscale conditions associated with heat extremes over the northwest U.S. by utilizing CMIP5 global climate model simulations, and dynamically downscaled regional climate models. An analysis of changes in mid- to low-level tropospheric temperature, offshore/onshore flow, soil moisture, precipitation, and cloud fraction are described, as well as how these changes interact with regional terrain and land/water contrasts to alter the temperature distributions over the region. CMIP5 models suggest that low-level zonal wind distributions over the northwest U.S. become narrower, leading to fewer days with strong offshore flow. Soil moisture is projected to decline over the region due to reductions in clouds and precipitation, as well as general warming. Historical and future regional temperature distributions will be described, and it will be shown that even though climate models predict increases in heat extremes for western Oregon and Washington, these increases are far fewer compared to inland areas. The variance over most inland locations increases, with the exception of the northwest U.S., where variance doesn't change. The importance of regional terrain and land/water contrasts in explaining these changes will be described.

  19. 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

  20. 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

    2016-08-09

    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

  1. Twentieth century temperature trends in CMIP3, CMIP5, and CESM-LE climate simulations: Spatial-temporal uncertainties, differences, and their potential sources

    NASA Astrophysics Data System (ADS)

    Kumar, Sanjiv; Kinter, James L.; Pan, Zaitao; Sheffield, Justin

    2016-08-01

    The twentieth century climate simulations from the Coupled Model Intercomparison Project Phase 3 (CMIP3) and Phase 5 (CMIP5) are compared to assess the models' ability to capture observed near-surface air temperature trends at global, continental, and regional scales. We computed trends by using a nonparametric method and considering long-term persistence in the time series. The role of internal variability is examined by using large ensemble climate simulations from the National Center for Atmospheric Research model Community Earth System Model (CESM). We computed temperature trends for three periods: the twentieth century, the second half of the twentieth century, and (3) the recent hiatus period to contrast the roles of external forcing and internal variability at various spatial and temporal scales. Both CMIP ensembles show statistically significant warming at global and continental scales during the twentieth century. We found a small but statistically significant difference between CMIP3 (0.57 ± 0.07 °C/century) and CMIP5 (0.47 ± 0.06 °C/century) twentieth century temperature trends, with the CMIP3 estimate being closer to the observations. The spatial structure of long-term temperature trends, and top-of-the atmosphere net radiation trends, suggests that differences in model parameterizations and feedback processes that lead to a smaller net radiative forcing are likely contributing to the differences between CMIP3 and CMIP5. The estimate of internal variability based on the CESM large ensemble spans 24% of the uncertainty in CMIP5 for the twentieth century temperature trends, and 76% for the recent hiatus period, both at global scales, and 43% and almost 100% during the corresponding time periods at regional scales.

  2. 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.

  3. 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.

  4. 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.

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

    SciTech Connect

    CULLEN, D. E.

    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, 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.

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

    NASA Astrophysics Data System (ADS)

    Schnack, D. D.; Cheng, J.; Barnes, D. C.; Parker, S. E.

    2013-06-01

    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∥/k⊥≪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 LTi0, instability requires that either k⊥ρi or ρi/LTi0 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 =ωr+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⊥ρi and ρi/LTi0 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⊥ρi or ρi/LTi0 increases. There is good qualitative agreement between the models for the shape of the unstable global eigenfunction for LTi0/ρi=30 and 20. The results quantify how far fluid calculations can be extended accurately into the kinetic regime. We conclude that for the linear ITG

  7. Geophysical trends from 12+ years of AIRS radiance trends

    NASA Astrophysics Data System (ADS)

    Desouza-Machado, S. G.; Strow, L. L.; Tangborn, A.; Hepplewhite, C.; Motteler, H.

    2014-12-01

    AIRS has been providing low noise, stable top-of-the atmospherehyperspectral radiances since 2002. In this presentation we use tworadiance subsets; (1) clear-sky scenes over ocean and (2) all-skyscenes along the nadir track. The linear trends of the AIRS spectralradiances are used to retrieve a variety of geophysical trends usingan optimal estimation approach. These retrieved clear sky trendscompare favorably with ERA and MERRA re-analysis trends, and in-situtrends for the minor gases. Preliminary analysis of all-sky trends(using radiance time derivatives) agree better with ERA than eitherMERRA or the AIRS Level-2 retrievals. Trends in cloud radiativeforcing are also examined using probability distribution functions(pdfs) of the AIRS radiances for regional subsets. These are comparedto ERA simulated radiances. These radiance and radiance PDF trendsprovide highly accurate measurements of atmospheric variability witheasily understood error characteristics, unlike Level 2 retrievals.These analysis approaches should provide highly accurate measurementsof a variety of climate trends (temperature and humidity profiles,land surface temperature, cloud radiative forcing) as the AIRS (orAIRS + JPSS/CrIS) instrument time-series soon extends to 15+ years.

  8. In-situ validation of remotely sensed land surface temperatures in high-arctic land regions - implications for gap filling and trend analyses

    NASA Astrophysics Data System (ADS)

    Westermann, S.; Langer, M.; Ostby, T.; Boike, J.; Schuler, T.; Etzelmuller, B.

    2015-12-01

    We present a summary of validation efforts of MODIS land surface temperature (MOD11A1, MYD11A1) using in-situ observations from the high-arctic sites Ny-Ålesund (79 °N) and Austfonna ice cap (80 °N) on Svalbard, as well as Samoylov Island in NE Siberia (72 °N). For all three sites, multi-year time series of outgoing and incoming long-wave radiation are available from which the skin temperature can be calculated. Our analysis is focused on long-term averages of all-sky temperatures which are required to determine trends of surface temperatures. At all sites, yearly averages computed from all available MODIS LST measurements are cold-biased by up to 3 °C, which is mainly caused by a significant cold-bias during the winter period. A closer analysis using in-situ observations of cloudiness reveals two main error sources. First, winter surface temperatures are systematically warmer for cloudy skies, so that the satellite predominantly samples "cold" clear-sky conditions. Secondly, the cloud detection algorithm fails to exclude a significant number of cloudy scenes, so that colder cloud top temperatures are contained in the surface temperature record. For the Austfonna ice cap, we estimate that the fraction of such cloud top temperatures could exceed 40%, which highlights the importance of this error source. Over the N Atlantic region, the number of MODIS LST retrievals varies by up to a factor of three, with highest numbers on the Greenland ice sheet and lowest numbers on Iceland the coastal regions of Norway. When assessing trends in land surface temperatures through remote sensing, three factors must be considered: a) trends in the "true" fraction of cloudy conditions, b) trends in the surface temperature for cloudy conditions, and c) trends in misidentified cloudy scenes and cloud top temperatures. We demonstrate that a simple gap-filling procedure using downscaled air temperatures from the ERA-interim reanalysis can significantly improve the agreement with in

  9. Unified trend of superconducting transition temperature versus Hall coefficient for ultrathin FeSe films prepared on different oxide substrates

    NASA Astrophysics Data System (ADS)

    Shiogai, Junichi; Miyakawa, Tomoki; Ito, Yukihiro; Nojima, Tsutomu; Tsukazaki, Atsushi

    2017-03-01

    High transition temperature (Tc) superconductivity in FeSe/SrTi O3 has been widely discussed on the possible mechanisms in conjunction with the various effects of interface between FeSe and SrTi O3 substrate. By employing an electric-double-layer transistor configuration, which enables both the electrostatic carrier doping and electrochemical thickness tuning, we investigated the interfacial effect on the high-Tc phase at around 40 K in FeSe films deposited on SrTi O3 , MgO, and KTa O3 substrates. The systematic study on thickness dependence of transport properties under a certain gate voltage reveals the universal trend of the onset Tc against the Hall coefficient in all the FeSe films, irrespective of the substrate materials in which the different contribution of interfacial effect is expected. The independence of the highest Tc on substrate materials evidences that the high-Tc superconductivity at around 40 K does not primarily originate from a specific interface combination but from a charge carrier filling at specific electronic band structure.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  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. 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

  16. 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.

  17. Statistics of regional surface temperatures post year 1900. Long-range versus short-range dependence, and significance of warming trends.

    NASA Astrophysics Data System (ADS)

    Løvsletten, Ola; Rypdal, Martin; Rypdal, Kristoffer; Fredriksen, Hege-Beate

    2015-04-01

    We explore the statistics of instrumental surface temperature records on 5°× 5°, 2°× 2°, and equal-area grids. In particular, we compute the significance of determinstic trends against two parsimonious null models; auto-regressive processes of order 1, AR(1), and fractional Gaussian noises (fGn's). Both of these two null models contain a memory parameter which quantifies the temporal climate variability, with white noise nested in both classes of models. Estimates of the persistence parameters show significant positive serial correlation for most grid cells, with higher persistence over occeans compared to land areas. This shows that, in a trend detection framework, we need to take into account larger spurious trends than what follows from the frequently used white noise assumption. Tested against the fGn null hypothesis, we find that ~ 68% (~ 47%) of the time series have significant trends at the 5% (1%) significance level. If we assume an AR(1) null hypothesis instead, then the result is that ~ 94% (~ 88%) of the time series have significant trends at the 5% (1%) significance level. For both null models, the locations where we do not find significant trends are mostly the ENSO regions and the North-Atlantic. We try to discriminate between the two null models by means of likelihood-ratios. If we at each grid point choose the null model preferred by the model selection test, we find that ~ 82% (~ 73%) of the time series have significant trends at the 5% (1%). We conclude that there is emerging evidence of significant warming trends also at regional scales, although with a much lower signal-to-noise ratio compared to global mean temperatures. Another finding is that many temperature records are consistent with error models for internal variability that exhibit long-range dependence, whereas the temperature fluctuations of the tropical oceans are strongly influenced by the ENSO, and therefore seemingly more consistent with random processes with short

  18. 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.

  19. 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.

  20. 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

  1. Two Americas. Comparisons of U.S. Child Poverty in Rural, Inner City and Suburban Areas. A Linear Trend Analysis to the Year 2010.

    ERIC Educational Resources Information Center

    Cook, John T.; Brown, J. Larry

    This analysis, part of a series on child poverty in America, contains an overview of child poverty trends over the period from 1959 to 1992 and projections of child poverty rates and levels by area of residence to the year 2010. Analyses, based on data from the Census Bureau, show a marked increase in the overall rate of child poverty since the…

  2. Laser induced fluorescence measurements of axial velocity, velocity shear, and parallel ion temperature profiles during the route to plasma turbulence in a linear magnetized plasma device

    NASA Astrophysics Data System (ADS)

    Chakraborty Thakur, S.; Adriany, K.; Gosselin, J. J.; McKee, J.; Scime, E. E.; Sears, S. H.; Tynan, G. R.

    2016-11-01

    We report experimental measurements of the axial plasma flow and the parallel ion temperature in a magnetized linear plasma device. We used laser induced fluorescence to measure Doppler resolved ion velocity distribution functions in argon plasma to obtain spatially resolved axial velocities and parallel ion temperatures. We also show changes in the parallel velocity profiles during the transition from resistive drift wave dominated plasma to a state of weak turbulence driven by multiple plasma instabilities.

  3. High-resolution, high-linearity temperature sensor using surface acoustic wave device based on LiNbO3/SiO2/Si substrate

    NASA Astrophysics Data System (ADS)

    Tian, Xiang-Guang; Liu, Heng; Tao, Lu-Qi; Yang, Yi; Jiang, Hanjun; Ren, Tian-Ling

    2016-09-01

    A high-resolution and high-linearity surface acoustic wave (SAW) temperature sensor, consisting of a SAW resonator device fabricated on novel X-cut LiNbO3/SiO2/Si piezoelectric substrate and a resonance frequency readout chip using standard 180 nm CMOS technology, is presented for the first time. High temperature performance substrate LiNbO3/SiO2/Si is prepared mainly by ion implantation and wafer bonding at first. RF SAW device with resonance frequency near 900 MHz is designed and fabricated on the substrate. Traditional probe method using network analyzer and the readout chip method are both implemented to characterize the fabricated SAW device. Further measurement of temperature using resonance frequency shift of SAW device demonstrates the feasibility of the combined system as a portable SAW temperature sensor. The obtained frequency-temperature relation of the fabricated device is almost linear. The frequency resolution of the readout chip is 733 Hz and the corresponding temperature accuracy is 0.016 ° C. Resolution of the sensor in this work is superior to most of the commercial temperature measurement sensors. Theory analysis and finite element simulation are also presented to prove the mechanism and validity of using SAW device for temperature detection applications. We conclude that the high-linearity frequency-temperature relation is achieved by the offset between high-order coefficients of LiNbO3 and SiO2 with opposite signs. This work offers the possibility of temperature measuring in ultra-high precision sensing and control applications.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

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

  6. 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.

  7. 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

    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.

  8. 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

  9. Investigation of the 1D symmetrical linear graded superconductor-dielectric photonic crystals and its potential applications as an optimized low temperature sensors

    NASA Astrophysics Data System (ADS)

    Baraket, Zina; Zaghdoudi, Jihene; Kanzari, Mounir

    2017-02-01

    Based on the Transfer Matrix Method (TMM) and the two fluid model for a superconductor and by taking account of the thermal expansion effect and thermo optical effects, we theoretically investigates the transmittance spectra of a one dimensional superconductor -dielectric photonic crystal (PC) designed as ((HLS)5/(SLH)5) made up of a BiGeO12(H), SiO2(L) and YaBO2CuO7 (S). The transmittance spectra shows that the system realizes a tunable filter which depends on a nonlinear relation with temperature. It's found that the symmetrical application of a linear deformation d(m) = d0+(m-1).δd(m) where d0 is the initial thickness of the layer m, δd(m) is the elementary added thickness at each layer. This linear gradation of the thickness permits to improve the temperature sensitivity of the system which acts as an optimized low temperature sensor.

  10. An upper-branch Brewer-Dobson circulation index for attribution of stratospheric variability and improved ozone and temperature trend analysis

    NASA Astrophysics Data System (ADS)

    Ball, William T.; Kuchař, Aleš; Rozanov, Eugene V.; Staehelin, Johannes; Tummon, Fiona; Smith, Anne K.; Sukhodolov, Timofei; Stenke, Andrea; Revell, Laura; Coulon, Ancelin; Schmutz, Werner; Peter, Thomas

    2016-12-01

    We find that wintertime temperature anomalies near 4 hPa and 50° N/S are related, through dynamics, to anomalies in ozone and temperature, particularly in the tropical stratosphere but also throughout the upper stratosphere and mesosphere. These mid-latitude anomalies occur on timescales of up to a month, and are related to changes in wave forcing. A change in the meridional Brewer-Dobson circulation extends from the middle stratosphere into the mesosphere and forms a temperature-change quadrupole from Equator to pole. We develop a dynamical index based on detrended, deseasonalised mid-latitude temperature. When employed in multiple linear regression, this index can account for up to 60 % of the total variability of temperature, peaking at ˜ 5 hPa and dropping to 0 at ˜ 50 and ˜ 0.5 hPa, respectively, and increasing again into the mesosphere. Ozone similarly sees up to an additional 50 % of variability accounted for, with a slightly higher maximum and strong altitude dependence, with zero improvement found at 10 hPa. Further, the uncertainty on all equatorial multiple-linear regression coefficients can be reduced by up to 35 and 20 % in temperature and ozone, respectively, and so this index is an important tool for quantifying current and future ozone recovery.

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

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

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

  12. 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.

  13. 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

  14. 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

  15. 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...

  16. 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.

  17. 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.

  18. In situ monitoring of the acetylene decomposition and gas temperature at reaction conditions for the deposition of carbon nanotubes using linear Raman scattering.

    PubMed

    Reinhold-López, Karla; Braeuer, Andreas; Popovska, Nadejda; Leipertz, Alfred

    2010-08-16

    To understand the reaction mechanisms taking place by growing carbon nanotubes via the catalytic chemical vapor deposition process, a strategy to monitor in situ the gas phase at reaction conditions was developed applying linear Raman spectroscopy. The simultaneous determination of the gas temperature and composition was possible by a new strategy of the evaluation of the Raman spectra. In agreement to the well-known exothermic decomposition of acetylene, a gas temperature increase was quantified when acetylene was added to the incident flow. Information about exhaust gas recirculation and location of the maximal acetylene conversion was derived from the composition measurements.

  19. [Dust storms trend in the Capital Circle of China over the past 50 years and its correlation with temperature, precipitation and wind].

    PubMed

    Chen, Yu-fu; Tang, Hai-ping

    2005-01-01

    The trends of number of dust storm days of the selected 11 meteorological stations from their established year to 2000 as well as their correlations with temperature, precipitation and wind are revealed. The number of dust storm days of the Capital Circle of China is distinctly variable in space and time. The numbers of dust storm days of the western area are far more than those of the eastern area. The interannual variability of number of dust storm days is remarkable. The number of dust storm days of the following 7 stations, Erlianhaote, Abaga, Xilinhaote, Fengning, Zhangjiakou, Huailai and Beijing, declined along the past decades, but those of the other four stations had no significant upward or downward trends. There is a marked seasonality of the number of dust storm days, and the maximum was in April. The correlation between number of dust storm days and number of days of mean wind velocity > 5 m/s, which is critical wind velocity to entrain sand into the air, was strongest among the three climatic factor. There were significant positive correlations between the number of dust storm days and number of days of mean wind velocity > 5 m/s in 6 stations. The second strongest climatic factor correlated with the number of dust storm days is temperature. There are significant negative correlations between the number of dust storm days and mean annual temperature, mean winter temperature, mean spring temperature in 3 or 4 stations. The correlation between the number of dust storm days and precipitation is weakest. Only one station, Zhurihe, showes significant negative correlation between the number of dust storm days and spring rainfall. There are 4 stations whose number of dust storm days don't significantly correlate with the climate. In the end, the spatial-temporal variability of dust storms and its relation with climate in the Capital Circle of China were discussed thoroughly.

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. 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

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

    To fully understand past climatic changes and their forcing factors, detailed reconstructions of past summer and winter temperatures are required. Winter temperature reconstructions are scarce, however, because most biological proxies are biased towards the growing season. This study presents a detailed reconstruction of winter temperatures based on Chrysophyte stomatocysts, silicious scales formed by so-called 'golden algae'. Previous studies (Kamenik and Schmidt, 2005; Pla and Catalan, 2005) have demonstrated the sensitivity of these algae to cold-season temperatures. Chrysophyte stomatocyst analysis was carried out on varved sediments from Lake Silvaplana (1791 m a.s.l.) at annual to near-annual resolution for two periods; AD 1100-1500 and AD 1870-2004. For both periods the reference date 'date of spring mixing' (Smix) was reconstructed using a transfer function developed for the Austrian Alps (Kamenik and Schmidt, 2005). In the Austrian Alps, Smix was primarily driven by air temperature in the cold season. The strength of stomatocysts as a proxy for winter temperature was tested by directly comparing reconstructed Smix with measured temperatures from nearby meteostation Sils Maria for the period AD 1870 - 2004. Correlation was highest (R = -0.6; p < 0.001) with mean October-April temperatures. The good agreement between reconstructed Smix and mean winter temperatures was interrupted only from AD 1925 - AD 1951, which was related to exceptionally high winter precipitation (thick snowpack) extending the ice-covered period. Strong lake eutrophication after AD 1950 only weakly affected the reconstruction of winter temperature. The winter temperature reconstruction (AD 1100-1500) shows strong interdecadal variability, superimposed on a cooling trend from around AD 1400 onwards. A direct comparison to summer temperature reconstructions based on biogenic silica and chironomid analysis from the same cores (Trachsel et al., in review; Larocque-Tobler et al., accepted

  7. Piezoelectric Non-Linear Nanomechanical Temperature and Acceleration Insensitive Clocks (PENNTAC) Phase 1 Evaluation and Plans for Phase 2

    DTIC Science & Technology

    2013-05-01

    integrated serpentine heater and by means of direct measurement of bifurcation via a high speed optical interferometer. - For fast variations in power...a total variation of 83 ppm between 25 and 85 °C. - Ovenize the mechanical resonator by embedding a serpentine heater into the body of the resonator...Fig. 5). The serpentine acts simultaneously as a heater and temperature sensor, which can be used to monitor temperature variations in the

  8. A note on the correlation between circular and linear variables with an application to wind direction and air temperature data in a Mediterranean climate

    NASA Astrophysics Data System (ADS)

    Lototzis, M.; Papadopoulos, G. K.; Droulia, F.; Tseliou, A.; Tsiros, I. X.

    2017-02-01

    There are several cases where a circular variable is associated with a linear one. A typical example is wind direction that is often associated with linear quantities such as air temperature and air humidity. The analysis of a statistical relationship of this kind can be tested by the use of parametric and non-parametric methods, each of which has its own advantages and drawbacks. This work deals with correlation analysis using both the parametric and the non-parametric procedure on a small set of meteorological data of air temperature and wind direction during a summer period in a Mediterranean climate. Correlations were examined between hourly, daily and maximum-prevailing values, under typical and non-typical meteorological conditions. Both tests indicated a strong correlation between mean hourly wind directions and mean hourly air temperature, whereas mean daily wind direction and mean daily air temperature do not seem to be correlated. In some cases, however, the two procedures were found to give quite dissimilar levels of significance on the rejection or not of the null hypothesis of no correlation. The simple statistical analysis presented in this study, appropriately extended in large sets of meteorological data, may be a useful tool for estimating effects of wind on local climate studies.

  9. Influence of climate change on the frequency of daytime temperature inversions and stagnation events in the Po Valley: historical trend and future projections

    NASA Astrophysics Data System (ADS)

    Caserini, Stefano; Giani, Paolo; Cacciamani, Carlo; Ozgen, Senem; Lonati, Giovanni

    2017-02-01

    This work analyzes the frequency of days characterized by daytime temperature inversion and air stagnation events in the Po valley area. The analysis is focused on both historical series and future projections under climate change. Historical sounding data from two different Italian stations are used as well as future projections data, provided by CMCC-CCLM 4-8-19 regional climate model (MED-CORDEX initiative). A new method to detect layers of temperature inversion is also presented. The developed method computes the occurrence of a temperature inversion layer for a given day at 12 UTC without a detailed knowledge of temperature vertical profile. This method was validated using sounding data and applied to the model projections, under two different emissions scenarios (RCP4.5 and RCP8.5). Under RCP4.5 intermediate emissions scenario, the occurrence of temperature inversions is projected to increase by 12 days/year (around + 10%) in the last decade of 21st century compared to 1986-2005 average. However, the increase in temperature inversions seems to be especially concentrated in the warm period. Under RCP8.5 extreme scenario, temperature inversions are still projected to increase, though to a lesser extent compared to RCP4.5 scenario (+ 6 days/year in the last decade of 21st century). A similar trend was found also for air stagnation events, which take into account the variation of precipitation pattern and wind strength. The expected increases are equal to + 13 days/year and + 11 days/year in the last decade of 21st century compared to 1986-2005 average, under RCP4.5 and RCP8.5 scenarios respectively.

  10. 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.

    2016-11-01

    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.

  11. 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.

  12. 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

  13. 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.

  14. Non-linear scaling of oxygen consumption and heart rate in a very large cockroach species (Gromphadorhina portentosa): correlated changes with body size and temperature.

    PubMed

    Streicher, Jeffrey W; Cox, Christian L; Birchard, Geoffrey F

    2012-04-01

    Although well documented in vertebrates, correlated changes between metabolic rate and cardiovascular function of insects have rarely been described. Using the very large cockroach species Gromphadorhina portentosa, we examined oxygen consumption and heart rate across a range of body sizes and temperatures. Metabolic rate scaled positively and heart rate negatively with body size, but neither scaled linearly. The response of these two variables to temperature was similar. This correlated response to endogenous (body mass) and exogenous (temperature) variables is likely explained by a mutual dependence on similar metabolic substrate use and/or coupled regulatory pathways. The intraspecific scaling for oxygen consumption rate showed an apparent plateauing at body masses greater than about 3 g. An examination of cuticle mass across all instars revealed isometric scaling with no evidence of an ontogenetic shift towards proportionally larger cuticles. Published oxygen consumption rates of other Blattodea species were also examined and, as in our intraspecific examination of G. portentosa, the scaling relationship was found to be non-linear with a decreasing slope at larger body masses. The decreasing slope at very large body masses in both intraspecific and interspecific comparisons may have important implications for future investigations of the relationship between oxygen transport and maximum body size in insects.

  15. 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.

  16. 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 between planetary period oscillation (PPO) phase and temperature in the northern main auroral oval.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  18. High-dynamic-range linear analog data links (1-20 GHz) using room temperature DFB laser diodes

    NASA Astrophysics Data System (ADS)

    White, Ian H.; Hartmann, Peter; Ingham, Jonathan D.; Webster, Matthew; Wake, David; Wonfor, Adrian; Penty, Richard V.; Seeds, Alwyn J.; White, J. Kenton

    2004-02-01

    We report the analysis and application of uncooled, directly-modulated high-speed DFB lasers with emphasis on their analogue transmission performance. Fibre-optic links employing such lasers are shown to meet the most stringent requirements of analogue systems at both high carrier frequencies and high temperatures. Spurious-free dynamic ranges (SFDR) exceeding 100dB×Hz2/3 and 90dB×Hz2/3 and input third-order intercept points (IIP3) above 20dBm and 18dBm are reported for carrier frequencies up to 20GHz at 25°C and up to 10GHz at 85°C, respectively. The error-vector magnitude (EVM) for a 256-QAM modulated signal transmitted over 15km of SMF remains below 1.9% for carrier frequencies of both 2GHz and 5GHz for all measured temperatures. The link performance is assessed by using 3GPP W-CDMA, IEEE 802.11a and IEEE 802.11b signals. In all cases the EVM remains within the standard specification, for fibre-optic link lengths of up to 10km and laser operating temperatures of up to 70°C. Finally, an IEEE 802.11b WLAN demonstrator is presented, allowing antenna remoting over up to 1000m of 62.5/125μm MMF.

  19. Finite Element Based Stress Analysis of Graphite Component in High Temperature Gas Cooled Reactor Core Using Linear and Nonlinear Irradiation Creep Models

    SciTech Connect

    Mohanty, Subhasish; Majumdar, Saurindranath

    2015-01-01

    Irradiation creep plays a major role in the structural integrity of the graphite components in high temperature gas cooled reactors. Finite element procedures combined with a suitable irradiation creep model can be used to simulate the time-integrated structural integrity of complex shapes, such as the reactor core graphite reflector and fuel bricks. In the present work a comparative study was undertaken to understand the effect of linear and nonlinear irradiation creep on results of finite element based stress analysis. Numerical results were generated through finite element simulations of a typical graphite reflector.

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

    SciTech Connect

    Xu, L; Baldocchi, DD

    2003-09-01

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

  1. Statistical properties of record-breaking temperatures.

    PubMed

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

    2010-12-01

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

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

    PubMed

    Chaudhuri, Sutapa; Dutta, Debashree

    2014-08-01

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

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

    NASA Technical Reports Server (NTRS)

    Walker, K. P.

    1981-01-01

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

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

    PubMed Central

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

    2015-01-01

    No records exist to evaluate long-term pH dynamics in high-latitude oceans, which have the greatest probability of rapid acidification from anthropogenic CO2 emissions. We reconstructed both seasonal variability and anthropogenic change in seawater pH and temperature by using laser ablation high-resolution 2D images of stable boron isotopes (δ11B) on a long-lived coralline alga that grew continuously through the 20th century. Analyses focused on four multiannual growth segments. We show a long-term decline of 0.08 ± 0.01 pH units between the end of the 19th and 20th century, which is consistent with atmospheric CO2 records. Additionally, a strong seasonal cycle (∼0.22 pH units) is observed and interpreted as episodic annual pH increases caused by the consumption of CO2 during strong algal (kelp) growth in spring and summer. The rate of acidification intensifies from –0.006 ± 0.007 pH units per decade (between 1920s and 1960s) to –0.019 ± 0.009 pH units per decade (between 1960s and 1990s), and the episodic pH increases show a continuous shift to earlier times of the year throughout the centennial record. This is indicative of ecosystem shifts in shallow water algal productivity in this high-latitude habitat resulting from warming and acidification. PMID:25713385

  5. Linear Chains of Magnetic Ions Stacked with Variable Distance: Ferromagnetic Ordering with a Curie Temperature above 20 K.

    PubMed

    Friedländer, Stefan; Liu, Jinxuan; Addicoat, Matt; Petkov, Petko; Vankova, Nina; Rüger, Robert; Kuc, Agnieszka; Guo, Wei; Zhou, Wencai; Lukose, Binit; Wang, Zhengbang; Weidler, Peter G; Pöppl, Andreas; Ziese, Michael; Heine, Thomas; Wöll, Christof

    2016-10-04

    We have studied the magnetic properties of the SURMOF-2 series of metal-organic frameworks (MOFs). Contrary to bulk MOF-2 crystals, where Cu(2+) ions form paddlewheels and are antiferromagnetically coupled, in this case the Cu(2+) ions are connected via carboxylate groups in a zipper-like fashion. This unusual coupling of the spin 1/2 ions within the resulting one-dimensional chains is found to stabilize a low-temperature, ferromagnetic (FM) phase. In contrast to other ordered 1D systems, no strong magnetic fields are needed to induce the ferromagnetism. The magnetic coupling constants describing the interaction between the individual metal ions have been determined in SQUID experiments. They are fully consistent with the results of ab initio DFT electronic structure calculations. The theoretical results allow the unusual magnetic behavior of this exotic, yet easy-to-fabricate, material to be described in a detailed fashion.

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

    SciTech Connect

    Fläschner, G.; Ruschmeier, K.; Schwarz, A. Wiesendanger, R.; Bakhtiari, M. R.; Thorwart, M.

    2015-03-23

    The sensitivity of atomic force microscopes is fundamentally limited by the cantilever temperature, which can be, in principle, determined by measuring its thermal spectrum and applying the equipartition theorem. However, the mechanical response can be affected by the light field inside the cavity of a Fabry-Perot interferometer due to light absorption, radiation pressure, photothermal forces, and laser noise. By evaluating the optomechanical Hamiltonian, we are able to explain the peculiar distance dependence of the mechanical quality factor as well as the appearance of thermal spectra with symmetrical Lorentzian as well as asymmetrical Fano line shapes. Our results can be applied to any type of mechanical oscillator in an interferometer-based detection system.

  7. Investigation of Low Temperature Non-Linear Magnetization Behavior in Al and Ga - Substituted La0.4Bi0.6Mno3 Manganites

    NASA Astrophysics Data System (ADS)

    Dayal, Vijaylakshmi; v, Punith Kumar; Hadimani, Ravi; Jiles, David; David C Jiles Team; Vijaylakshmi Dayal Collaboration

    Low temperature magnetization measurements have been carried out for the samples containing Al and Ga at B-site in La0.4Bi0.6MnO3 manganites. The magnetization (M) vs. T(K) data shows strong ferromagnetic behavior with highest magnetization of 6.45 emu/g for La0.4Bi0.6Mn0.95Al0.05O3 and 5.40 emu/g for La0.4Bi0.6Mn0.90Al0.1O3 samples respectively for an applied magnetic field of H =100 Oe at T =20 K. Similarly at T =20 K for La0.4Bi0.6Mn0.95Ga0.05O3 the highest magnetization (MS) was found to be 5.44 emu/g and for La0.4Bi0.6Mn0.90Ga0.1O3 the MS is 5.05 emu/g. The decrease in magnetization with both Al and Ga substitution produces magnetic dilution with increasing concentrations. Both Al and Ga substituted samples exhibit non-linear behavior in their magnetization (MNL) curves around 40 -120 K due to the frustrations arising from mismatch in their magnetic spin arrangements. The quantity non linear susceptibility, χNL = - MNL/H, diverges as the temperature approaches the frustrated region Tf from above (i.e.TC) . Further from dχNL/dT vs. T(K) plots and critical analysis with unusual critical exponent's γ and β gives an experimental evidence for the observed non linearity and magnetic frustration.

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

    PubMed

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

    2013-01-22

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

  9. High-Temperature Ethanol Fermentation and Transformation with Linear DNA in the Thermotolerant Yeast Kluyveromyces marxianus DMKU3-1042▿

    PubMed Central

    Nonklang, Sanom; Abdel-Banat, Babiker M. A.; Cha-aim, Kamonchai; Moonjai, Nareerat; Hoshida, Hisashi; Limtong, Savitree; Yamada, Mamoru; Akada, Rinji

    2008-01-01

    We demonstrate herein the ability of Kluyveromyces marxianus to be an efficient ethanol producer and host for expressing heterologous proteins as an alternative to Saccharomyces cerevisiae. Growth and ethanol production by strains of K. marxianus and S. cerevisiae were compared under the same conditions. K. marxianus DMKU3-1042 was found to be the most suitable strain for high-temperature growth and ethanol production at 45°C. This strain, but not S. cerevisiae, utilized cellobiose, xylose, xylitol, arabinose, glycerol, and lactose. To develop a K. marxianus DMKU3-1042 derivative strain suitable for genetic engineering, a uracil auxotroph was isolated and transformed with a linear DNA of the S. cerevisiae ScURA3 gene. Surprisingly, Ura+ transformants were easily obtained. By Southern blot hybridization, the linear ScURA3 DNA was found to have inserted randomly into the K. marxianus genome. Sequencing of one Lys− transformant confirmed the disruption of the KmLYS1 gene by the ScURA3 insertion. A PCR-amplified linear DNA lacking K. marxianus sequences but containing an Aspergillus α-amylase gene under the control of the ScTDH3 promoter together with an ScURA3 marker was subsequently used to transform K. marxianus DMKU3-1042 in order to obtain transformants expressing Aspergillus α-amylase. Our results demonstrate that K. marxianus DMKU3-1042 can be an alternative cost-effective bioethanol producer and a host for transformation with linear DNA by use of S. cerevisiae-based molecular genetic tools. PMID:18931291

  10. An extended linear scaling method for downscaling temperature and its implication in the Jhelum River basin, Pakistan, and India, using CMIP5 GCMs

    NASA Astrophysics Data System (ADS)

    Mahmood, Rashid; JIA, Shaofeng

    2016-08-01

    In this study, the linear scaling method used for the downscaling of temperature was extended from monthly scaling factors to daily scaling factors (SFs) to improve the daily variations in the corrected temperature. In the original linear scaling (OLS), mean monthly SFs are used to correct the future data, but mean daily SFs are used to correct the future data in the extended linear scaling (ELS) method. The proposed method was evaluated in the Jhelum River basin for the period 1986-2000, using the observed maximum temperature (Tmax) and minimum temperature (Tmin) of 18 climate stations and the simulated Tmax and Tmin of five global climate models (GCMs) (GFDL-ESM2G, NorESM1-ME, HadGEM2-ES, MIROC5, and CanESM2), and the method was also compared with OLS to observe the improvement. Before the evaluation of ELS, these GCMs were also evaluated using their raw data against the observed data for the same period (1986-2000). Four statistical indicators, i.e., error in mean, error in standard deviation, root mean square error, and correlation coefficient, were used for the evaluation process. The evaluation results with GCMs' raw data showed that GFDL-ESM2G and MIROC5 performed better than other GCMs according to all the indicators but with unsatisfactory results that confine their direct application in the basin. Nevertheless, after the correction with ELS, a noticeable improvement was observed in all the indicators except correlation coefficient because this method only adjusts (corrects) the magnitude. It was also noticed that the daily variations of the observed data were better captured by the corrected data with ELS than OLS. Finally, the ELS method was applied for the downscaling of five GCMs' Tmax and Tmin for the period of 2041-2070 under RCP8.5 in the Jhelum basin. The results showed that the basin would face hotter climate in the future relative to the present climate, which may result in increasing water requirements in public, industrial, and agriculture

  11. HSO2+ formation from ion-molecule reactions of SO2.+ with water and methane: two fast reactions with reverse temperature-dependent kinetic trend.

    PubMed

    Cartoni, Antonella; Catone, Daniele; Bolognesi, Paola; Satta, Mauro; Markus, Pal; Avaldi, Lorenzo

    2017-02-08

    In this work an experimental and theoretical study on the formation of HSO2+ ion from the SO2.+ + CH4 and SO2.+ + H2O ion-molecule reactions at different temperatures is reported. Tunable synchrotron radiation has been used to produce the SO2.+ ion in excited ro-vibrational levels of the ionic ground state X2A1 and mass spectrometry has been employed to identify the product ions. Calculations in the frame of the density functional theory and variational transtition state theory have been combined to explore the dynamics of the reactions. The experimental results show that HSO2+ is the only product in both reactions. Its yield decreases monotonically with photon energy in the SO2.+ + H2O reaction, while it decreases at first and then increases in the SO2.+ + CH4 reaction. Theory confirms this trend by calculating the rate constants at different temperatures and explains the results by means of the polar, spin and charge effects as well as structural reorganization occuring in the reaction coordinate. The dynamic behavior observed in these two reactions is of general and fundamental interest. It can also provide some insights in the role of these reactions in astrochemistry as well as in their use as models for bond-activation reactions.

  12. Exploring C-water-temperature interactions and non-linearities in soils through developments in process-based models

    NASA Astrophysics Data System (ADS)

    Esteban Moyano, Fernando; Vasilyeva, Nadezda; Menichetti, Lorenzo

    2016-04-01

    Soil carbon models developed over the last couple of decades are limited in their capacity to accurately predict the magnitudes and temporal variations in observed carbon fluxes and stocks. New process-based models are now emerging that attempt to address the shortcomings of their more simple, empirical counterparts. While a spectrum of ideas and hypothetical mechanisms are finding their way into new models, the addition of only a few processes known to significantly affect soil carbon (e.g. enzymatic decomposition, adsorption, Michaelis-Menten kinetics) has shown the potential to resolve a number of previous model-data discrepancies (e.g. priming, Birch effects). Through model-data validation, such models are a means of testing hypothetical mechanisms. In addition, they can lead to new insights into what soil carbon pools are and how they respond to external drivers. In this study we develop a model of soil carbon dynamics based on enzymatic decomposition and other key features of process based models, i.e. simulation of carbon in particulate, soluble and adsorbed states, as well as enzyme and microbial components. Here we focus on understanding how moisture affects C decomposition at different levels, both directly (e.g. by limiting diffusion) or through interactions with other components. As the medium where most reactions and transport take place, water is central en every aspect of soil C dynamics. We compare results from a number of alternative models with experimental data in order to test different processes and parameterizations. Among other observations, we try to understand: 1. typical moisture response curves and associated temporal changes, 2. moisture-temperature interactions, and 3. diffusion effects under changing C concentrations. While the model aims at being a process based approach and at simulating fluxes at short time scales, it remains a simplified representation using the same inputs as classical soil C models, and is thus potentially

  13. NASA trend analysis procedures

    NASA Technical Reports Server (NTRS)

    1993-01-01

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

  14. Northern Hemisphere Meridional and Zonal Temperature Gradients and their Relation to Hydrologic Extremes at Mid-latitudes: Trends, Variability and Link to Climate Modes in Observations and Simulations

    NASA Astrophysics Data System (ADS)

    Karamperidou, C.; Lall, U.; Cioffi, F.

    2010-12-01

    The mid-latitude storm track, which depends on how the jet stream dynamics (mean flow and transient eddies coupled to it) are modulated by large scale ocean-land boundary conditions, is a factor in determining moisture and heat transport associated with extreme hydrologic events, such as floods and droughts. These boundary conditions depend in turn on both the state of evolution of the known interannual and multi-decadal natural variability (e.g., the El Niño-Southern Oscillation (ENSO) and the North Atlantic Oscillation (NAO)) and on changes in meridional and zonal surface temperature gradients (Equator-to-Pole and Ocean-Land contrast, respectively) due to anthropogenic forcing. We examine the historical trends of the seasonal NH Equator-to-Pole temperature Gradient (EPG) and the Ocean-Land temperature Contrast (OLC), their probability structure, and their potential relation to anthropogenic warming. We investigate how different combinations of EPG and OLC are associated with precipitation anomalies at mid-latitudes, with a focus in the US and European region. Figure 1 shows an example of how the combination of high OLC- low EPG is associated with positive precipitation anomalies in the aforementioned regions (upper panel), while the combination of low EPG-high OLC is linked to average conditions or negative precipitation anomalies (lower panel), data from Eischeid et al. (1991). We also explore their relation to modes of variability, such as ENSO, as exhibited in observational data and GCM simulations, and utilize GCM projections to estimate potential changes in the frequency and persistence of certain combinations of EPG and OLC associated with precipitation anomalies under climate change scenarios. Winter (DJF) precipitation anomalies for two cases of combinations of EPG and OLC. (a) High OLC and low EPG corresponds to positive anomalies. (b) Low OLC and high EPG corresponds to near zero or negative anomalies for most regions. Data from Eischeid et al (1991).

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  16. Response of the Summertime Ground-level Ozone Trend in the Chicago Area to Emission Controls and Temperature Changes 2005-2013

    NASA Astrophysics Data System (ADS)

    Jing, P.; Lu, Z.; Xing, J.; Streets, D. G.; Tan, Q.; O'Brien, T.; Kamberos, J.

    2014-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

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

  18. Modelling the Relationship Between Land Surface Temperature and Landscape Patterns of Land Use Land Cover Classification Using Multi Linear Regression Models

    NASA Astrophysics Data System (ADS)

    Bernales, A. M.; Antolihao, J. A.; Samonte, C.; Campomanes, F.; Rojas, R. J.; dela Serna, A. M.; Silapan, J.

    2016-06-01

    The threat of the ailments related to urbanization like heat stress is very prevalent. There are a lot of things that can be done to lessen the effect of urbanization to the surface temperature of the area like using green roofs or planting trees in the area. So land use really matters in both increasing and decreasing surface temperature. It is known that there is a relationship between land use land cover (LULC) and land surface temperature (LST). Quantifying this relationship in terms of a mathematical model is very important so as to provide a way to predict LST based on the LULC alone. This study aims to examine the relationship between LST and LULC as well as to create a model that can predict LST using class-level spatial metrics from LULC. LST was derived from a Landsat 8 image and LULC classification was derived from LiDAR and Orthophoto datasets. Class-level spatial metrics were created in FRAGSTATS with the LULC and LST as inputs and these metrics were analysed using a statistical framework. Multi linear regression was done to create models that would predict LST for each class and it was found that the spatial metric "Effective mesh size" was a top predictor for LST in 6 out of 7 classes. The model created can still be refined by adding a temporal aspect by analysing the LST of another farming period (for rural areas) and looking for common predictors between LSTs of these two different farming periods.

  19. Effects of temperature dependent conductivity and absorptive/generative heat transfer on MHD three dimensional flow of Williamson fluid due to bidirectional non-linear stretching surface

    NASA Astrophysics Data System (ADS)

    Bilal, S.; Khalil-ur-Rehman; Malik, M. Y.; Hussain, Arif; Khan, Mair

    Present work is communicated to identify characteristics of magnetohydrodynamic (MHD) three dimensional boundary layer flow of Williamson fluid confined by a bidirectional stretched surface. Conductivity of working fluid is assumed to be temperature dependent. Generative/absorptive heat transfer is also taken into account. Mathematical model is formulated in the form of partial expressions and then transmuted into ordinary differential equations with the help of newfangled set of similarity transformations. The resulting non-linear differential system of equations is solved numerically with the aid of Runge-Kutta algorithm supported by shooting method. Flow features are exemplified quantitatively through graphs. Scintillating results for friction factor and convective heat transfer are computed and scrutinized tabularly. Furthermore, the accuracy of present results is tested with existing literature and we found an excellent agreement. It is inferred that velocity along x-direction mounts whereas along y-direction depreciates for incrementing values of stretching ratio parameter. Moreover, it is also elucidated that non-linearity index tends to decrement the velocity and thermal distributions of fluid flow.

  20. Dendroclimatic transfer functions revisited: Little Ice Age and Medieval Warm Period summer temperatures reconstructed using artificial neural networks and linear algorithms

    NASA Astrophysics Data System (ADS)

    Helama, S.; Makarenko, N. G.; Karimova, L. M.; Kruglun, O. A.; Timonen, M.; Holopainen, J.; Meriläinen, J.; Eronen, M.

    2009-03-01

    Tree-rings tell of past climates. To do so, tree-ring chronologies comprising numerous climate-sensitive living-tree and subfossil time-series need to be "transferred" into palaeoclimate estimates using transfer functions. The purpose of this study is to compare different types of transfer functions, especially linear and nonlinear algorithms. Accordingly, multiple linear regression (MLR), linear scaling (LSC) and artificial neural networks (ANN, nonlinear algorithm) were compared. Transfer functions were built using a regional tree-ring chronology and instrumental temperature observations from Lapland (northern Finland and Sweden). In addition, conventional MLR was compared with a hybrid model whereby climate was reconstructed separately for short- and long-period timescales prior to combining the bands of timescales into a single hybrid model. The fidelity of the different reconstructions was validated against instrumental climate data. The reconstructions by MLR and ANN showed reliable reconstruction capabilities over the instrumental period (AD 1802-1998). LCS failed to reach reasonable verification statistics and did not qualify as a reliable reconstruction: this was due mainly to exaggeration of the low-frequency climatic variance. Over this instrumental period, the reconstructed low-frequency amplitudes of climate variability were rather similar by MLR and ANN. Notably greater differences between the models were found over the actual reconstruction period (AD 802-1801). A marked temperature decline, as reconstructed by MLR, from the Medieval Warm Period (AD 931-1180) to the Little Ice Age (AD 1601-1850), was evident in all the models. This decline was approx. 0.5°C as reconstructed by MLR. Different ANN based palaeotemperatures showed simultaneous cooling of 0.2 to 0.5°C, depending on algorithm. The hybrid MLR did not seem to provide further benefit above conventional MLR in our sample. The robustness of the conventional MLR over the calibration

  1. Highly Efficient p-i-n Perovskite Solar Cells Utilizing Novel Low-Temperature Solution-Processed Hole Transport Materials with Linear π-Conjugated Structure.

    PubMed

    Li, Yang; Xu, Zheng; Zhao, Suling; Qiao, Bo; Huang, Di; Zhao, Ling; Zhao, Jiao; Wang, Peng; Zhu, Youqin; Li, Xianggao; Liu, Xicheng; Xu, Xurong

    2016-09-01

    Alternative low-temperature solution-processed hole-transporting materials (HTMs) without dopant are critical for highly efficient perovskite solar cells (PSCs). Here, two novel small molecule HTMs with linear π-conjugated structure, 4,4'-bis(4-(di-p-toyl)aminostyryl)biphenyl (TPASBP) and 1,4'-bis(4-(di-p-toyl)aminostyryl)benzene (TPASB), are applied as hole-transporting layer (HTL) by low-temperature (sub-100 °C) solution-processed method in p-i-n PSCs. Compared with standard poly(3,4-ethylenedioxythiophene): poly(styrenesulfonic acid) (PEDOT:PSS) HTL, both TPASBP and TPASB HTLs can promote the growth of perovskite (CH3 NH3 PbI3 ) film consisting of large grains and less grain boundaries. Furthermore, the hole extraction at HTL/CH3 NH3 PbI3 interface and the hole transport in HTL are also more efficient under the conditions of using TPASBP or TPASB as HTL. Hence, the photovoltaic performance of the PSCs is dramatically enhanced, leading to the high efficiencies of 17.4% and 17.6% for the PSCs using TPASBP and TPASB as HTL, respectively, which are ≈40% higher than that of the standard PSC using PEDOT:PSS HTL.

  2. Quantitative methods for stochastic high frequency spatio-temporal and non-linear analysis: Assessing health effects of exposure to extreme ambient temperature

    NASA Astrophysics Data System (ADS)

    Liss, Alexander

    Extreme weather events, such as heat waves and cold spells, cause substantial excess mortality and morbidity in the vulnerable elderly population, and cost billions of dollars. The accurate and reliable assessment of adverse effects of extreme weather events on human health is crucial for environmental scientists, economists, and public health officials to ensure proper protection of vulnerable populations and efficient allocation of scarce resources. However, the methodology for the analysis of large national databases is yet to be developed. The overarching objective of this dissertation is to examine the effect of extreme weather on the elderly population of the Conterminous US (ConUS) with respect to seasonality in temperature in different climatic regions by utilizing heterogeneous high frequency and spatio-temporal resolution data. To achieve these goals the author: 1) incorporated dissimilar stochastic high frequency big data streams and distinct data types into the integrated data base for use in analytical and decision support frameworks; 2) created an automated climate regionalization system based on remote sensing and machine learning to define climate regions for the Conterminous US; 3) systematically surveyed the current state of the art and identified existing gaps in the scientific knowledge; 4) assessed the dose-response relationship of exposure to temperature extremes on human health in relatively homogeneous climate regions using different statistical models, such as parametric and non-parametric, contemporaneous and asynchronous, applied to the same data; 5) assessed seasonal peak timing and synchronization delay of the exposure and the disease within the framework of contemporaneous high frequency harmonic time series analysis and modification of the effect by the regional climate; 6) modeled using hyperbolic functional form non-linear properties of the effect of exposure to extreme temperature on human health. The proposed climate

  3. Modelling the association of dengue fever cases with temperature and relative humidity in Jeddah, Saudi Arabia-A generalised linear model with break-point analysis.

    PubMed

    Alkhaldy, Ibrahim

    2017-04-01

    The aim of this study was to examine the role of environmental factors in the temporal distribution of dengue fever in Jeddah, Saudi Arabia. The relationship between dengue fever cases and climatic factors such as relative humidity and temperature was investigated during 2006-2009 to determine whether there is any relationship between dengue fever cases and climatic parameters in Jeddah City, Saudi Arabia. A generalised linear model (GLM) with a break-point was used to determine how different levels of temperature and relative humidity affected the distribution of the number of cases of dengue fever. Break-point analysis was performed to modelled the effect before and after a break-point (change point) in the explanatory parameters under various scenarios. Akaike information criterion (AIC) and cross validation (CV) were used to assess the performance of the models. The results showed that maximum temperature and mean relative humidity are most probably the better predictors of the number of dengue fever cases in Jeddah. In this study three scenarios were modelled: no time lag, 1-week lag and 2-weeks lag. Among these scenarios, the 1-week lag model using mean relative humidity as an explanatory variable showed better performance. This study showed a clear relationship between the meteorological variables and the number of dengue fever cases in Jeddah. The results also demonstrated that meteorological variables can be successfully used to estimate the number of dengue fever cases for a given period of time. Break-point analysis provides further insight into the association between meteorological parameters and dengue fever cases by dividing the meteorological parameters into certain break-points.

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

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

  5. Trend analysis of the long-term Swiss ozone measurements

    NASA Technical Reports Server (NTRS)

    Staehelin, Johannes; Bader, Juerg; Gelpke, Verena

    1994-01-01

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

  6. Temperature-Dependent Non-linear Resistive Switching Characteristics and Mechanism Using a New W/WO3/WOx/W Structure

    NASA Astrophysics Data System (ADS)

    Chakrabarti, Somsubhra; Samanta, Subhranu; Maikap, Siddheswar; Rahaman, Sheikh Ziaur; Cheng, Hsin-Ming

    2016-09-01

    Post-metal annealing temperature-dependent forming-free resistive switching memory characteristics, Fowler-Nordheim (F-N) tunneling at low resistance state, and after reset using a new W/WO3/WOx/W structure have been investigated for the first time. Transmission electron microscope image shows a polycrystalline WO3/WOx layer in a device with a size of 150 × 150 nm2. The composition of WO3/WOx is confirmed by X-ray photo-electron spectroscopy. Non-linear bipolar resistive switching characteristics have been simulated using space-charge limited current (SCLC) conduction at low voltage, F-N tunneling at higher voltage regions, and hopping conduction during reset, which is well fitted with experimental current-voltage characteristics. The barrier height at the WOx/W interface for the devices annealed at 500 °C is lower than those of the as-deposited and annealed at 400 °C (0.63 vs. 1.03 eV). An oxygen-vacant conducting filament with a diameter of ~34 nm is formed/ruptured into the WO3/WOx bilayer owing to oxygen ion migration under external bias as well as barrier height changes for high-resistance to low-resistance states. In addition, the switching mechanism including the easy method has been explored through the current-voltage simulation. The devices annealed at 500 °C have a lower operation voltage, lower barrier height, and higher non-linearity factor, which are beneficial for selector-less crossbar memory arrays.

  7. Linear mode conversion of Langmuir/z-mode waves to radiation: Scalings of conversion efficiencies and propagation angles with temperature and magnetic field orientation

    SciTech Connect

    Schleyer, F.; Cairns, Iver H.; Kim, E.-H.

    2013-03-15

    Linear mode conversion (LMC) is the linear transfer of energy from one wave mode to another in an inhomogeneous plasma. It is relevant to laboratory plasmas and multiple solar system radio emissions, such as continuum radiation from planetary magnetospheres and type II and III radio bursts from the solar corona and solar wind. This paper simulates LMC of waves defined by warm, magnetized fluid theory, specifically the conversion of Langmuir/z-mode waves to electromagnetic (EM) radiation. The primary focus is the calculation of the energy and power conversion efficiencies for LMC as functions of the angle of incidence {theta} of the Langmuir/z-mode wave, temperature {beta}=T{sub e}/m{sub e}c{sup 2}, adiabatic index {gamma}, and orientation angle {phi} between the ambient density gradient {nabla}N{sub 0} and ambient magnetic field B{sub 0} in a warm, unmagnetized plasma. The ratio of these efficiencies is found to agree well as a function of {theta}, {gamma}, and {beta} with an analytical relation that depends on the group speeds of the Langmuir/z and EM wave modes. The results demonstrate that the energy conversion efficiency {epsilon} is strongly dependent on {gamma}{beta}, {phi} and {theta}, with {epsilon}{proportional_to}({gamma}{beta}){sup 1/2} and {theta}{proportional_to}({gamma}{beta}){sup 1/2}. The power conversion efficiency {epsilon}{sub p}, on the other hand, is independent of {gamma}{beta} but does vary significantly with {theta} and {phi}. The efficiencies are shown to be maximum for approximately perpendicular density gradients ({phi} Almost-Equal-To 90 Degree-Sign ) and minimal for parallel orientation ({phi}=0 Degree-Sign ) and both the energy and power conversion efficiencies peak at the same {theta}.

  8. Assessing recent trends in high-latitude Southern Hemisphere surface climate

    NASA Astrophysics Data System (ADS)

    Jones, Julie M.; Gille, Sarah T.; Goosse, Hugues; Abram, Nerilie J.; Canziani, Pablo O.; Charman, Dan J.; Clem, Kyle R.; Crosta, Xavier; de Lavergne, Casimir; Eisenman, Ian; England, Matthew H.; Fogt, Ryan L.; Frankcombe, Leela M.; Marshall, Gareth J.; Masson-Delmotte, Valérie; Morrison, Adele K.; Orsi, Anaïs J.; Raphael, Marilyn N.; Renwick, James A.; Schneider, David P.; Simpkins, Graham R.; Steig, Eric J.; Stenni, Barbara; Swingedouw, Didier; Vance, Tessa R.

    2016-10-01

    Understanding the causes of recent climatic trends and variability in the high-latitude Southern Hemisphere is hampered by a short instrumental record. Here, we analyse recent atmosphere, surface ocean and sea-ice observations in this region and assess their trends in the context of palaeoclimate records and climate model simulations. Over the 36-year satellite era, significant linear trends in annual mean sea-ice extent, surface temperature and sea-level pressure are superimposed on large interannual to decadal variability. Most observed trends, however, are not unusual when compared with Antarctic palaeoclimate records of the past two centuries. With the exception of the positive trend in the Southern Annular Mode, climate model simulations that include anthropogenic forcing are not compatible with the observed trends. This suggests that natural variability overwhelms the forced response in the observations, but the models may not fully represent this natural variability or may overestimate the magnitude of the forced response.

  9. Instructional Time Trends. Education Trends

    ERIC Educational Resources Information Center

    Woods, Julie Rowland

    2015-01-01

    For more than 30 years, Education Commission of the States has tracked instructional time and frequently receives requests for information about policies and trends. In this Education Trends report, Education Commission of the States addresses some of the more frequent questions, including the impact of instructional time on achievement, variation…

  10. Thermal Analysis of Non-linear Convective-Radiative Hyperbolic Lumped Systems with Simultaneous Variation of Temperature-Dependent Specific Heat and Surface Emissivity by MsDTM and BPES

    NASA Astrophysics Data System (ADS)

    Torabi, Mohsen; Yaghoobi, Hessameddin; Boubaker, Karem

    2013-01-01

    With the advent of temperatures near absolute zero, it is often claimed that at very low temperatures the effect of thermal wave propagation must be included by the hyperbolic heat conduction equation (HHCE). In this paper the non-linear convective-radiative HHCE is investigated. Opposite to common numerical analyses, analytical expressions are obtained for the temperature variations by the multi-step differential transformation method. Some conclusions about alteration of the specific heat of the material, temperature steeping, and Vernotte number have been formulated.

  11. Linear Accelerators

    NASA Astrophysics Data System (ADS)

    Sidorin, Anatoly

    2010-01-01

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

  12. Program Trends.

    ERIC Educational Resources Information Center

    Moss, Jeffrey W.; And Others

    1989-01-01

    Articles by Moss, Van Huss, Raynor, Lynch, and Sullivan discuss the trends in all areas of vocational education. Includes information on how new technologies, life-styles, and job demands have changed or should change vocational education. (JOW)

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

    PubMed

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

    2014-03-01

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

  14. Room temperature rechargeable magnesium batteries with sulfur-containing composite cathodes prepared from elemental sulfur and bis(alkenyl) compound having a cyclic or linear ether unit

    NASA Astrophysics Data System (ADS)

    Itaoka, Kanae; Kim, In-Tae; Yamabuki, Kazuhiro; Yoshimoto, Nobuko; Tsutsumi, Hiromori

    2015-11-01

    Room temperature rechargeable magnesium (Mg) batteries are constructed from Mg as a negative material, sulfur (S)-containing composite prepared from elemental sulfur and the bis(alkenyl) compound having a crown ether unit (BUMB18C6) or linear ether unit (UOEE) as a positive material and the simple electrolyte (0.7 mol dm-3 Mg[N(SO2CF3)2]2-triglyme (G3) solution). The reaction between molten S and the bis(alkenyl) compound (BUMB18C6 or UOEE) provides the sulfur-containing composite, S-BUMB18C6 or S-UOEE. Both of the sulfur-containing composites are electrochemically active in the Mg salt-based electrolyte, acetonitrile- or G3- Mg[N(SO2CF3)2]2 electrolyte. The first discharge capacity of the test cells with the sulfur-containing composite is 460 Ah kg-1 (per the weight of sulfur in the composite) with the S-BUMB18C6 electrode and 495 Ah kg-1 with the S-UOEE electrode. According to the continuous charge-discharge cycle tests (at 10th cycle), the discharge capacity of the test cell with the S-BUMB18C6 electrode (68.1 Ah kg-1) is higher than that with the S-UOEE electrode (0.18 Ah kg-1). The crown ether units in the S-BUMB18C6 composite may create ion-conducting paths in the cathode, prevent rise in the internal resistance of the cathode, and provide better cycle performance of the test cells with the S-BUMB18C6 composite electrode than that with the S-UOEE electrode.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  16. Room temperature dehydrogenation of ethane, propane, linear alkanes C4-C8, and some cyclic alkanes by titanium-carbon multiple bonds.

    PubMed

    Crestani, Marco G; Hickey, Anne K; Gao, Xinfeng; Pinter, Balazs; Cavaliere, Vincent N; Ito, Jun-Ichi; Chen, Chun-Hsing; Mindiola, Daniel J

    2013-10-02

    The transient titanium neopentylidyne, [(PNP)Ti≡C(t)Bu] (A; PNP(-)≡N[2-P(i)Pr2-4-methylphenyl]2(-)), dehydrogenates ethane to ethylene at room temperature over 24 h, by sequential 1,2-CH bond addition and β-hydrogen abstraction to afford [(PNP)Ti(η(2)-H2C═CH2)(CH2(t)Bu)] (1). Intermediate A can also dehydrogenate propane to propene, albeit not cleanly, as well as linear and volatile alkanes C4-C6 to form isolable α-olefin complexes of the type, [(PNP)Ti(η(2)-H2C═CHR)(CH2(t)Bu)] (R = CH3 (2), CH2CH3 (3), (n)Pr (4), and (n)Bu (5)). Complexes 1-5 can be independently prepared from [(PNP)Ti═CH(t)Bu(OTf)] and the corresponding alkylating reagents, LiCH2CHR (R = H, CH3(unstable), CH2CH3, (n)Pr, and (n)Bu). Olefin complexes 1 and 3-5 have all been characterized by a diverse array of multinuclear NMR spectroscopic experiments including (1)H-(31)P HOESY, and in the case of the α-olefin adducts 2-5, formation of mixtures of two diastereomers (each with their corresponding pair of enantiomers) has been unequivocally established. The latter has been spectroscopically elucidated by NMR via C-H coupled and decoupled (1)H-(13)C multiplicity edited gHSQC, (1)H-(31)P HMBC, and dqfCOSY experiments. Heavier linear alkanes (C7 and C8) are also dehydrogenated by A to form [(PNP)Ti(η(2)-H2C═CH(n)Pentyl)(CH2(t)Bu)] (6) and [(PNP)Ti(η(2)-H2C═CH(n)Hexyl)(CH2(t)Bu)] (7), respectively, but these species are unstable but can exchange with ethylene (1 atm) to form 1 and the free α-olefin. Complex 1 exchanges with D2C═CD2 with concomitant release of H2C═CH2. In addition, deuterium incorporation is observed in the neopentyl ligand as a result of this process. Cyclohexane and methylcyclohexane can be also dehydrogenated by transient A, and in the case of cyclohexane, ethylene (1 atm) can trap the [(PNP)Ti(CH2(t)Bu)] fragment to form 1. Dehydrogenation of the alkane is not rate-determining since pentane and pentane-d12 can be dehydrogenated to 4 and 4-d12 with comparable

  17. Influence of Temperature on Optical Properties of Silver Nanoparticle-Transparent Matrix Composites

    NASA Astrophysics Data System (ADS)

    Kalenskii, A. V.; Zvekov, A. A.; Nikitin, A. P.

    2017-01-01

    Individual optical properties of silver nanoparticles and their composites with transparent matrices were calculated at wavelength 1060 nm and various temperatures. It was shown that the absorption coefficient of the nanoparticles depended almost linearly on temperature whereas the scattering efficiency and anisotropy depended weakly on temperature. The coefficients of reflectance and transmission of a slab decreased and the effective absorption coefficient increased as the temperature increased. The studied trends could be used to obtain temperature dependences of metal optical properties.

  18. Environmental Trends.

    ERIC Educational Resources Information Center

    Council on Environmental Quality, Washington, DC.

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

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

    NASA Astrophysics Data System (ADS)

    Sayemuzzaman, M.; Jha, M. K.

    2013-12-01

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

  20. NASA standard: Trend analysis techniques

    NASA Technical Reports Server (NTRS)

    1990-01-01

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