Science.gov

Sample records for linear temperature trends

  1. Propagation of linear surface air temperature trends into the terrestrial subsurface

    E-print Network

    Beltrami, Hugo

    robust estimates of multidecadal to centennial temperature changes at the Earth's surface for several hun of lowfrequency changes in the temperature at the Earth's surface during the last millennium [Cermak, 1971; HuangPropagation of linear surface air temperature trends into the terrestrial subsurface Marielle

  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 Ni?o-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 analysis over southwest Iran: trends and projections

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

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

  6. Temperature trends in the lower mesosphere

    SciTech Connect

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

    1991-03-01

    The largest atmospheric temperature changes due to the increase of greenhouse gases are expected in the 40 to 60 km altitude region, where enhanced infrared cooling decreases the temperature. Ten-year (1980-1990) temperature trends at 55 km and 0.4 mb, derived using data from the ground-based lidar at Haute Provence, 44{degree}N 6{degree}E, and the SSU channel 47X on several satellites, are presented. These data show temperature decreases that are as large and in some cases exceed predictions based on current models. At 44{degree}N, the ground-based lidar and satellite techniques give a negative trend of {minus}0.10 {plus minus} 0.04% per year and {minus}0.14 {plus minus} 0.02% per year, respectively. Agreement between these two data sets based on different measurement techniques gives confidence in the detected trends at this latitude. Further analysis of the SSU 47X satellite data between 45{degree}S and 45{degree}N indicates a maximum decline of 0.16% per year near 30{degree}N. A minimum trend decrease of 0.07% per year is detected between 20{degree} and 30{degree}S. Based on NOAA satellite radiance observations, these long-term temperature changes are larger than changes at any of the other stratospheric levels below 55 km monitored during this period.

  7. Temperature trends in the lower mesosphere

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

    The largest atmospheric temperature changes due to the increase of greenhouse gases are expected in the 40 to 60 km altitude region, where enhanced infrared cooling decreases the temperature. Ten-year (1980-1990) temperature trends at 55 km and 0.4 mb, derived using data from the ground-based lidar at Haute Provence, (France), and the SSU-instrument channel 47X on several satellites, are presented. These data show temperature decreases that are as large and in some cases exceed predictions based on current models. At 44 deg N, the ground-based lidar and satellite techniques give a negative trend of -0.10 + or - 0.04 percent per year and -0.14 + or - 0.02 percent per year, respectively. Agreement between these two data sets based on different measurement techniques gives confidence in the detected trends at this latitude. Further analysis of the SSU 47X satellite data between 45 deg S and 45 deg N indicates a maximum decline of 0.16 percent per year near 30 deg N. A minimum trend decrease of 0.07 percent per year is detected between 20 and 30 deg S. Based on NOAA satellite radiance observations, these long-term temperature changes are larger than changes at any of the other stratospheric levels below 55 km monitored during this period.

  8. 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.

  9. The mystery of recent stratospheric temperature trends.

    PubMed

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

    2012-11-29

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

  10. 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 started. Also, the SST in the Arctic basin is observed to be anomalously high in 2007 when the perennial ice cover declined dramatically to its lowest extent. In the Antarctic, surface temperature trends are much more moderate with the most positive trends occurring in the Antarctic Peninsula and parts of Western Antarctica while some cooling are observed in the Antarctic Plateau and the Ross Sea. The trends in SST in the region is similar to global averages but precipitation from more evaporation may have a key role in the spatial distribution of surface temperature in the ice covered region

  11. Temperature trends in South Africa: 1960-2003

    NASA Astrophysics Data System (ADS)

    Kruger, A. C.; Shongwe, S.

    2004-12-01

    Time series of South African temperatures were investigated for temporal and spatial trends for the period 1960 to 2003. For this purpose a total of 26 climate stations were utilized, with each having sufficient data available and not having undergone major moves or changes in exposure that would influence the homogeneity of their data series. The vast majority, a total of 23 stations, showed positive trends in their annual mean maximum temperature series, 13 of them significant, with trends higher for central stations than those closer to the coast. Annual mean minimum temperatures showed 21 stations having positive trends, with 18 significant. Stations not showing significantly positive trends in annual mean minimum temperatures were mostly situated in the central interior. The annual average temperature data series of 24 of the stations showed positive trends, with 18 of them significant. Trends of mean seasonal temperature showed that temperature trends are not consistent throughout the year, with the average trend for autumn showing a maximum and spring a minimum. Monthly trends of average annual temperatures showed large differences in trend between stations, and for each station between months, but similar tendencies in trend between months were found to exist for stations close by and also for groups of stations on a regional basis. Trends in diurnal temperature range are almost equally divided between positive and negative, with the positive trends in the central interior mainly being caused by large positive trends in maximum temperature. It is also shown that, in general, days and nights with relatively high temperatures have increased, while days and nights with relatively low temperatures have decreased. The effects of urbanization on temperature trends are investigated, and the conclusion is that most stations regarded as urban stations are still useful for trend analysis; being situated on the outskirts of cities they are, therefore, not substantially influenced by the urban heat island. El Niño and La Niña events do not seem to play a significant role in the increasing temperatures observed.

  12. REVIEW OF MESOSPHERIC TEMPERATURE TRENDS P. Keckhut,2

    E-print Network

    REVIEW OF MESOSPHERIC TEMPERATURE TRENDS G. Beig,1 P. Keckhut,2 R. P. Lowe,3 R. G. Roble,4 M. G knowledge of systematic changes and trends in the temperature of the mesosphere and lower thermo- sphere/decade. On the other hand, a majority of studies indicate negative trends in the lower and middle mesosphere

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

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

  14. Trends in high temperature gas turbine materials

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

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

  15. Linearizing Thermistors for Use as Temperature

    E-print Network

    Rathbun, Julie A.

    temperature coefficient thermistors can be made to give a linear emf readout over a limited range if used combination in the top leg of an emf divider causes the output emf to rise as the temperature rises -- The basic thermistor emf divider. T meas Figure 3 --Response of the Figure 2 circuit. E out If, now, Rt

  16. Altitude dependence of atmospheric temperature trends: Climate models versus observation

    E-print Network

    Douglass, David H.

    . This disparity indicates that the three models examined here fail to account for the effects of greenhouse that greenhouse effects are stronger at mid- to high- tropospheric altitudes. The maximum temperature trend, whichAltitude dependence of atmospheric temperature trends: Climate models versus observation David H

  17. Ozone and temperature trends in the lower stratosphere

    NASA Technical Reports Server (NTRS)

    Miller, A. J.; Nagatani, R. M.; Tiao, G. C.; Niu, X. F.; Reinsel, G. C.; Wuebbles, D.; Grant, K.

    1992-01-01

    It is shown that the pattern of temperature trend with height in the upper troposphere and lower stratosphere is consistent with that calculated from a model incorporating the observed ozone changes. The magnitude of the observed temperature decrease is less than that determined from the numerical model. It is found that the obverse ozone-temperature relationship does not hold. If the temperature at 20 km decreases, this by itself would result in an increase in the ozone values through the inverse temperature sensitivity of the chemical reactions. In the lower stratosphere a positive correlation between ozone and temperature tends to exist through the dynamics. Ozone-rich air moving downward undergoes an increase in temperature through adiabatic compression and vice-versa. That the temperature trends indicate no apparent variation with latitude suggests a nondynamic cause.

  18. 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 (?Tw) were estimated by two different methods: (1) multiple regression incorporating year seasonality and linear trend; and (2) non-parametric Mann-Kendall seasonal trend estimator. A cluster analysis based on principal components (performed upon the variables Tw, ?Tw, annual Tw range, lag of the Tw annual cycle, coefficient of correlation between water and air temperature (Ta), and station altitude) allowed for grouping stations with similar behaviour in Tw (along the year, seasonality, and throughout the study period, trend). Trend analysis by the regression and Mann-Kendall methods produced similar results. They showed significant (P

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  20. 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.

  1. 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.

  2. Local trend disparities of European minimum and maximum temperature extremes

    NASA Astrophysics Data System (ADS)

    Franzke, Christian L. E.

    2015-08-01

    Ecosystems and societies are highly vulnerable to extreme temperatures and to changes in the range of temperatures at local scales. Here I will show how trends in warm and cold extremes have evolved over the last six decades in Europe on local scales. Comparing the slopes of two extreme quantiles demonstrates that there are significant disparities in trends of cold and warm temperature extremes at many locations in Europe. At some locations the range of extreme cold and hot temperatures increases, while at other locations it decreases. These results suggest that at some locations both warm and cold extremes intensify which seems to be contradictory to the prevailing view of global warming in which both cold and warm temperatures are expected to increase.

  3. Trends and Patterns of Change in Temperature and Evaporation

    NASA Astrophysics Data System (ADS)

    Ragno, E.; AghaKouchak, A.

    2014-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  5. Temperature Trends in the White Mountains of New Hampshire

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

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

    PubMed

    Marotzke, Jochem; Forster, Piers M

    2015-01-29

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

  7. 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.

  8. 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 with global datasets can provide some indication on biases. Compared to the global BEST dataset for the same countries, the national datasets of Austria, Italy and Switzerland have a 0.36°C per century stronger trend since 1901. For the trend since 1960 we can also take Australia, France and Slovenia into account and find a trend bias of 0.40°C per century. Relative to CRUCY the trend biases are smaller and only statistically significant for the period since 1980. The most direct way to study biases in the temperature records is by making parallel measurements with historical measurement set-ups. Several recent parallel data studies for the transition to Stevenson screens suggest larger biases: Austria 0.2°C, Spain 0.5 & 0.6°C. As well as older tropical ones: India 0.42°C and Sri Lanka 0.37°C. The smaller values from the Parker (1994) review mainly stem from parallel measurements from North-West Europe, which may have less problems with exposure. Furthermore, the influence of many historical transitions, especially the ones that could cause an artificial smaller trend, have not been studied in detail yet. We urgently need to study improvements of exposure (especially in the (sub-)tropics), increases in watering and irrigation, mechanical ventilation, better paints, relocations to airports, and relocations to suburbs of stations that started in the cities and from village centers to pasture, for example. Our current understanding surprisingly suggests that the more recent period may have the largest biases, but it could also be that even the best datasets are unable to improve earlier data sufficiently. If the temperature trend were actually larger it would reduce discrepancies between studies for a number of problems in climatology. For example, the estimates of transient climate sensitivity using instrumental data are lower as the one using climate models, volcanic eruptions or paleo data. Furthermore, several changes observed in the climate system are larger than expected. On the other hand, a large trend in the land surface temperature would make th

  9. 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.

  10. Disparity of tropospheric and surface temperature trends: New evidence

    E-print Network

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

    2004-01-01

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

  11. 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.

  12. Concurrent trends in snow cover and air temperature in Norway

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    At northern latitudes, the sensitivity to global warming is amplified as a result of the unique annual cycle and intensive growth season, which influences the radiative fluxes (e.g. the transport of energy). The Northern Hemisphere snow cover has a strong positive feedback on the energy balance through its influence on the surface albedo. A reduction in snow cover leads to a lowering of the albedo and thus, enhances the warming. Previous and ongoing research have revealed a major increase in air temperature for the whole of Norway, notable in winter and a general reduction in the snow cover at lower altitudes. In this study, we assess to what degree changes in snow cover (i.e. whether or not there is snow on the ground) can explain the enhanced temperature increase in winter. Daily time series of temperature, snow depth and snow cover area available for the whole of Norway at a spatial resolution of 1 km from seNorge (www.senorge.no) are analysed for the period 1958 to 2013. Data is successively aggregated for periods of 30 years (e.g., 1961-1990, 1971-2000, 1981-2010). The aim is threefold; i) to estimate trends and changes in the climate variables on a monthly basis for selected 30-year periods for the whole of Norway ii) to analyse spatial patterns and concurrent trends in the variable and iii) assess to what degree changes in snow cover can explain the enhanced winter temperature using statistical methods, e.g., the regression test. The Theil-Sen estimator was selected for the trend analysis as it considers the relative differences of all the pairs of data of the considered dataset and is less sensitive to outliers than other estimators. Preliminary results confirm an increasing trend in temperature (especially in winter months). A substantial change in the snow cover area throughout the year is found. Later snowfall is seen in the northern parts of Norway in October, gradually shifting southwards. In November, snow cover reduction is notable in the southern coastal area, and in December a diminishing snow cover is found primarily at the south-east coast. Further, the snow depth decreases over the whole of Norway with larger reduction seen from January to May in the eastern part of Norway. This is likely a result of a shift in precipitation from snow to rain in both the beginning of winter as well as in early spring. In April/May reduction in snow cover is found in the lowlands and throughout the summer a reduction is seen also further north and in the highlands.

  13. Detection and Attribution of Temperature Trends in the Presence of Natural Variability

    NASA Astrophysics Data System (ADS)

    Wallace, J. M.

    2014-12-01

    The fingerprint of human-induced global warming stands out clearly above the noise In the time series of global-mean temperature, but not local temperature. At extratropical latitudes over land the standard error of 50-year linear temperature trends at a fixed point is as large as the cumulative rise in global-mean temperature over the past century. Much of the samping variability in local temperature trends is "dynamically-induced", i.e., attributable to the fact that the seasonally-varying mean circulation varies substantially from one year to the next and anomalous circulation patterns are generally accompanied by anomalous temperature patterns. In the presence of such large sampling variability it is virtually impossible to identify the spatial signature of greenhouse warming based on observational data or to partition observed local temperature trends into natural and human-induced components. It follows that previous IPCC assessments, which have focused on the deterministic signature of human-induced climate change, are inherently limited as to what they can tell us about the attribution of the past record of local temperature change or about how much the temperature at a particular place is likely to rise in the next few decades in response to global warming. To obtain more informative assessments of regional and local climate variability and change it will be necessary to take a probabilistic approach. Just as the use of the ensembles has contributed to more informative extended range weather predictions, large ensembles of climate model simulations can provide a statistical context for interpreting observed climate change and for framing projections of future climate. For some purposes, statistics relating to the interannual variability in the historical record can serve as a surrogate for statistics relating to the diversity of climate change scenarios in large ensembles.

  14. An update on the global ozone climatology and on concurrent ozone and temperature trends

    SciTech Connect

    Fortuin, J.P.F.; Langematz, U.

    1995-12-31

    An attempt is made to construct a zonal and monthly mean ozone climatology for use in general circulation models, based on a combination of ozonesonde and satellite observations. One important advantage of such a climatology is a more realistic ozone distribution around the tropopause, where heating rates and climate forcing are most sensitive to changes in gas concentrations. Also, a linear trend study is performed, for the periods 1970--83 and 1980--93 separately, on concurrent ozone and temperature data obtained from a selection of ozonesonde stations. On average for northern polar- to mid-latitudes, these trends are insignificant for stratospheric ozone and temperature in the first period, but for the second period show a stratospheric ozone depletion and stratospheric cooling of around {minus}0.5%/year and {minus}0.15 K/year respectively. As for the troposphere in the same region, ozone shows an increase ({approximately} 1.5%/year) in the mid-troposphere but temperature trends are insignificant over the first period, versus no ozone trend but a clearly significant near-surface warming ({approximately} 0.2 K/year) in the second period. This average situation is however not representative for the separate regions it is composed of, i.e., Canada (4 stations), Japan (3 stations) and the US (1 station). Above Syowa station at the Antarctic coast, the acceleration in stratospheric ozone depletion as well as stratospheric cooling over the past two decades is clearly evident: from hardly significant ozone and temperature trends in the first period to values of up to {minus}4%/year and {minus}0.4 K/year respectively in the second period. In regions where near-surface ozone increase is evident over the past two decades, it is often accompanied by a significant near-surface warming.

  15. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

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

    E-print Network

    Østvand, Lene; Rypdal, Martin

    2013-01-01

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

  18. 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.

  19. 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.

  20. 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).

  1. 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.

  2. Anthropogenic trends vs. long-term correlations in temperature records: Solving the detection problem

    NASA Astrophysics Data System (ADS)

    Lennartz, S.; Bunde, A.

    2009-12-01

    It is well accepted that the global mean surface air temperature has been rising in the 20th century, with a more pronounced increase in the last 50 years. The open question is how much of this increase can be attributed to natural fluctuations, and how much is of anthropogenic origin, caused, for example, by the increasing greenhouse gas (GHG) emission. To treat this detection problem, we do not use climate simulations, but assume as statistical null hypothesis that monthly temperature records are long-term correlated with a Hurst exponent H >0.5 (including also nonstationary records with H values above 1). We are interested in the probability W(D) that an observed trend D occurs naturally, and in the anthropogenic part A(Q, D) of the temperature increase within a given confidence interval Q. We show that for confidence intervals with Q above 80% analytical expressions for W(D) and A(Q, D) can be derived, which request as input solely the Hurst exponent, as well as the temperature increase D obtained from the linear regression line and the standard deviation around it [1]. We apply this methodology to a large number of global and local stations, and find that in general, the trends in the global data are more significant than in the local data. In addition, our analysis yields the surprising result that the comparatively strong temperature increase in the last 50 years is a weaker indicator for an anthropogenic trend than the lower annual increase in the last 100 years. Ref.:[1] Lennartz, S., and A. Bunde, Geophys. Res. Lett. 36, L16706 (2009)

  3. Temperature Errors in Linearizing Resistance Networks for Thermistors

    NASA Astrophysics Data System (ADS)

    White, D. R.

    2015-08-01

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

  4. Room Temperature Accelerator Structures for Linear Colliders

    SciTech Connect

    Miller, Roger H.

    2001-09-10

    Early tests of short low group velocity and standing wave structures indicated the viability of operating X-band linacs with accelerating gradients in excess of 100 MeV/m. Conventional scaling of traveling wave traveling wave linacs with frequency scales the cell dimensions with {lambda}. Because Q scales as {lambda}{sup 1/2}, the length of the structures scale not linearly but as {lambda}{sup 3/2} in order to preserve the attenuation through each structure. For NLC we chose not to follow this scaling from the SLAC S-band linac to its fourth harmonic at X-band. We wanted to increase the length of the structures to reduce the number of couplers and waveguide drives which can be a significant part of the cost of a microwave linac. Furthermore, scaling the iris size of the disk-loaded structures gave unacceptably high short range dipole wakefields. Consequently, we chose to go up a factor of about 5 in average group velocity and length of the structures, which increases the power fed to each structure by the same factor and decreases the short range dipole wakes by a similar factor. Unfortunately, these longer (1.8 m) structures have not performed nearly as well in high gradient tests as the short structures. We believe we have at least a partial understanding of the reason and will discuss it below. We are now studying two types of short structures with large apertures with moderately good efficiency including: (1) traveling wave structures with the group velocity lowered by going to large phase advance per period with bulges on the iris, (2){pi} mode standing wave structures.

  5. North-Atlantic SST amplified recent European land temperature extremes and trends.

    E-print Network

    North-Atlantic SST amplified recent European land temperature extremes and trends. Julien Cattiaux dataset: daily mean temperature over 1950-2007. EGU 2010. Julien Cattiaux ­ North Atlantic SST amplified ­ North Atlantic SST amplified recent European land temperature extremes and trends. 2/12 Tobs anomalies

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

    NASA Astrophysics Data System (ADS)

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

    2011-07-01

    The recently concluded Surface Stations Project surveyed 82.5% of the U.S. Historical Climatology Network (USHCN) stations and provided a classification based on exposure conditions of each surveyed station, using a rating system employed by the National Oceanic and Atmospheric Administration to develop the U.S. Climate Reference Network. The unique opportunity offered by this completed survey permits an examination of the relationship between USHCN station siting characteristics and temperature trends at national and regional scales and on differences between USHCN temperatures and North American Regional Reanalysis (NARR) temperatures. This initial study examines temperature differences among different levels of siting quality without controlling for other factors such as instrument type. Temperature trend estimates vary according to site classification, with poor siting leading to an overestimate of minimum temperature trends and an underestimate of maximum temperature trends, resulting in particular in a substantial difference in estimates of the diurnal temperature range trends. The opposite-signed differences of maximum and minimum temperature trends are similar in magnitude, so that the overall mean temperature trends are nearly identical across site classifications. Homogeneity adjustments tend to reduce trend differences, but statistically significant differences remain for all but average temperature trends. Comparison of observed temperatures with NARR shows that the most poorly sited stations are warmer compared to NARR than are other stations, and a major portion of this bias is associated with the siting classification rather than the geographical distribution of stations. According to the best-sited stations, the diurnal temperature range in the lower 48 states has no century-scale trend.

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

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

  9. 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.V. 2009.

  10. Linear temperature dependence of the resistivity in the new superconductors

    SciTech Connect

    Civale, L.; Martinez, E.N.

    1988-07-01

    We present an elementary proof that, irrespective of dimensionality, the electrical resistivity of a simple conductor should be linear with temperature if T>2p/sub F/s/k/sub B/<temperature.

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

    USGS Publications Warehouse

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

    2006-01-01

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

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

    PubMed

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

    2015-11-12

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

  13. 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.

  14. Analysis of long-term temperature trends for selected reporting stations in North America

    SciTech Connect

    Walsh, T.J.

    1997-11-01

    This paper focuses on examining surface air temperature trends for selected reporting stations located in North America to determine if any global warming impacts could be realized on a regional or local basis. An examination of annual average temperatures for twenty stations located over a latitude range of approximately forty-five degrees was undertaken. A 5-year average temperature was calculated using each station`s annual average temperature. Some of the stations indicated slight upward temperature trends for the period of record, while others showed no trends or both upward and downward variations over time. The study confirms that the datasets used to assess long-term temperature trends at individual stations need to be examined for any differences so urban waste heat and other factors are considered. 7 refs., 4 figs., 1 tab.

  15. 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.

  16. 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.

    2015-04-01

    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.

  17. Assessing the consistency between short-term global temperature trends in observations and climate model projections

    E-print Network

    Michaels, Patrick J; Christy, John R; Herman, Chad S; Liljegren, Lucia M; Annan, James D

    2013-01-01

    Assessing the consistency between short-term global temperature trends in observations and climate model projections is a challenging problem. While climate models capture many processes governing short-term climate fluctuations, they are not expected to simulate the specific timing of these somewhat random phenomena - the occurrence of which may impact the realized trend. Therefore, to assess model performance, we develop distributions of projected temperature trends from a collection of climate models running the IPCC A1B emissions scenario. We evaluate where observed trends of length 5 to 15 years fall within the distribution of model trends of the same length. We find that current trends lie near the lower limits of the model distributions, with cumulative probability-of-occurrence values typically between 5 percent and 20 percent, and probabilities below 5 percent not uncommon. Our results indicate cause for concern regarding the consistency between climate model projections and observed climate behavior...

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    In the present study, tendencies in temperature, precipitation, and snow cover area over the southwestern part of Iran have been assessed. The research mainly focused on snow cover-observed period which included the months of December, January, February, March, and April in the area. This research has been divided into two parts. First part consists of an analysis of the trends in temperature, precipitation, and snow cover area during the above months. Trends in these parameters were tested by linear regression, and significance was determined by t test. Mann-Kendall rank test (MK test) was also employed to confirm the results of linear regression. Sequential Mann-Kendall test (SQ-MK test) was applied for change point detection in the series. For snow cover analysis, remote sensing images from National Oceanic and Atmospheric Administration (NOAA) satellite with advanced very high resolution radiometer (AVHRR) sensor for the period 1987-2007 were used. The second part of the research involved future projections based on four models under B1 and A1B emission scenarios. The models used were centre national de recherches meteorologiques (CNRM), European Center Hamburg model (ECHAM), Model for Interdisciplinary Research on Climate (MIROCH) and United Kingdom Meteorological Office (UKMOC) under the Intergovernmental Panel on Climate Change (IPCC) AR4. The analysis of temperature trends revealed a significant increase during February and April. Temperature projections showed that temperature may increase between 1.12 to 7.87 °C by 2100 in the study area. The results of precipitation series indicated that majority of the stations registered insignificant trends during the twentieth century. However, precipitation may decrease according to most of the models under both scenarios, but the decrease may not be large, except according to MIROCH model. The results of trend analysis of snow cover area indicated that no significant trends were detected by any statistical tests at 95 % confidence level during the twentieth century. Snow cover projection showed that snow cover area may decrease as indicated by all the models under both scenarios at the end of twenty-first century consistent with the projected increase in temperature.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  1. 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.

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

    E-print Network

    Robock, Alan

    Diurnal and seasonal cycles of trends of surface air temperature Konstantin Y. Vinnikov Department developed to study seasonal cycles of climatic trends of expected values, variance, skewness, and other statistical moments of climatic variables. Here we apply that technique to analyze the diurnal and seasonal

  3. 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

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

  4. 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

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

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

    NASA Astrophysics Data System (ADS)

    Black, Adam Leland

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

  6. Asymmetric trends in seasonal temperature variability based on long instrumental records

    NASA Astrophysics Data System (ADS)

    Matiu, Michael; Ankerst, Donna; Menzel, Annette

    2015-04-01

    While the increase in global mean temperature over the past several decades is widely accepted, the issue as to whether and to what extent temperature variability is changing has not been solved yet. Temperature variability as the width of the temperature distribution measures the likelihood of temperature extremes. Those changes can amplify, nullify or reduce the effect a gradual warming has on extremes. Since climatic extremes exert large impacts on society and ecology, effects of altered temperature variability must be considered in tandem with effects of a gradually increasing temperature mean. Previous studies of trends in mean temperature and its associated variability have produced conflicting results. Here we investigate 10 selected long-term climate records of minimum, mean and maximum temperatures in Switzerland, Germany and the UK. In detail, we analysed trends in seasonal, annual and decadal measures of variability (standard deviation and various quantile ranges) as well as asymmetries in the trends of extreme vs mean temperatures via quantile regression. Besides accelerated mean warming during 1864-2012, we found higher trends for Tmax than for Tmin in the last 40 years (1973-2012), amounting to up to 0.08°C yr-1 in spring. In contrast, variability trends were not as uniform: significant changes occurred in opposing directions depending on the season, as well as when comparing 1864-2012 trends to those of 1973-2012. Often, variability changed asymmetrically and consequently, trends in high and low extremes differed. More patterns were detected for spatial and seasonal variation in these changes of variability.

  7. A stable boundary layer perspective on global temperature trends

    NASA Astrophysics Data System (ADS)

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

    2010-08-01

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

  8. Attribution of European precipitation and temperature trends to changes in synoptic circulation

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    Surface climate in Europe is changing and patterns in trends have been found to vary at sub-seasonal scales. This study aims to contribute to a better understanding of these changes across space and time by analysing to what degree observed climatic trends can be attributed to changes in synoptic atmospheric circulation. The relative importance of synoptic circulation changes (i.e. trends in synoptic type frequencies) as opposed to trends in the hydrothermal properties of synoptic types (within-type trends) on precipitation and temperature trends in Europe is assessed on a monthly basis. The study is based on mapping spatial and temporal trend patterns and their variability at a relatively high resolution (0.5° × 0.5°; monthly) across Europe. Gridded precipitation and temperature data (1963-2001) originate from the Watch Forcing Data set and synoptic types are defined by the objective SynopVis Grosswetterlagen (SVG). During the study period, relatively high influence of synoptic circulation changes are found from January to March, contributing to wetting trends in northern Europe and drying in the south. Simultaneously, particularly dry synoptic types get warmer first in south-western Europe in November and/or December and affect most of Europe in March and/or April. Strong influence of synoptic circulation changes is again found in June and August. In general, changes in synoptic circulation has a stronger effect on climate trends in north-western Europe than in the south-east. The exact locations of the strongest influence of synoptic circulation changes vary with the time of year and to some degree between precipitation and temperature. Throughout the year and across the whole of Europe, precipitation and temperature trends are caused by a combination of synoptic circulation changes and within-type changes with their relative influence varying between regions, months and climate variables.

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

    PubMed

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

    2015-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

    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.

  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

    2015-05-01

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

  12. 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.

  13. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2007-12-01

    This paper documents various unresolved issues in using surface temperature trends as a metric for assessing global and regional climate change. A series of examples ranging from errors caused by temperature measurements at a monitoring station to the undocumented biases in the regionally and globally averaged time series are provided. The issues are poorly understood or documented and relate to micrometeorological impacts due to warm bias in nighttime minimum temperatures, poor siting of the instrumentation, effect of winds as well as surface atmospheric water vapor content on temperature trends, the quantification of uncertainties in the homogenization of surface temperature data, and the influence of land use/land cover (LULC) change on surface temperature trends. Because of the issues presented in this paper related to the analysis of multidecadal surface temperature we recommend that greater, more complete documentation and quantification of these issues be required for all observation stations that are intended to be used in such assessments. This is necessary for confidence in the actual observations of surface temperature variability and long-term trends.

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

    NASA Astrophysics Data System (ADS)

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

    2008-02-01

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

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

    NASA Astrophysics Data System (ADS)

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

    1982-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  18. Linearity between temperature peak and bioenergy CO2 emission rates

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  19. Analysis of sampling error uncertainties and trends in maximum and minimum temperatures in China

    NASA Astrophysics Data System (ADS)

    Hua, Wei; Shen, Samuel S. P.; Wang, Huijun

    2014-03-01

    In this paper we report an analysis of sampling error uncertainties in mean maximum and minimum temperatures (Tmax and Tmin) carried out on monthly, seasonal and annual scales, including an examination of homogenized and original data collected at 731 meteorological stations across China for the period 1951-2004. Uncertainties of the gridded data and national average, linear trends and their uncertainties, as well as the homogenization effect on uncertainties are assessed. It is shown that the sampling error variances of homogenized Tmax and Tmin, which are larger in winter than in summer, have a marked northwest-southeast gradient distribution, while the sampling error variances of the original data are found to be larger and irregular. Tmax and Tmin increase in all months of the year in the study period 1951-2004, with the largest warming and uncertainties being 0.400°C (10 yr)-1 ± 0.269°C (10 yr)-1 and 0.578°C (10 yr)-1 ± 0.211°C (10 yr)-1 in February, and the least being 0.022°C (10 yr)-1 ± 0.085°C (10 yr)-1 and 0.104°C (10 yr)-1 ±0.070°C (10 yr)-1 in August. Homogenization can remove large uncertainties in the original records resulting from various non-natural changes in China.

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

  1. Recent global warming hiatus dominated by low latitude temperature trends in surface and troposphere data

    NASA Astrophysics Data System (ADS)

    Gleisner, Hans; Thejll, Peter; Christiansen, Bo; Nielsen, Johannes K.

    2015-04-01

    Over the last 15 years, global mean surface temperatures exhibit only weak trends. Recent studies have attempted to attribute this so called temperature hiatus to several causes, amongst them incomplete sampling of the rapidly warming Arctic region. We here examine zonal mean temperature trends in satellite-based tropospheric data sets (MSU/AMSU and GNSS Radio Occultation) and in global surface temperatures (HadCRUT4). Omission of successively larger polar regions from the global-mean temperature calculations, in both tropospheric and surface data sets, shows that data gaps at high latitudes cannot explain the observed differences between the hiatus and the pre-hiatus period. Instead, the dominating causes of the global temperature hiatus are found at low latitudes. The combined use of several independent data sets, representing completely different measurement techniques and sampling characteristics, strengthens the conclusions.

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

    NASA Astrophysics Data System (ADS)

    van Wijngaarden, W. A.

    2015-11-01

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

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

    PubMed

    Hossain, Murshed

    2014-01-01

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

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

    PubMed Central

    Hossain, Murshed

    2015-01-01

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

  5. 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.

  6. 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 temperature gradient ranging from 0.02 to 0.04 °C/y), 1 station shows a significant negative trend (- 0.02 °C/y). The spatial dishomogeneity in the signal suggests that anthropic factors could influence very much the variations of temperatures in the last 60 years, preventing from using such data, like they are, as climatic indicators. The occurrence of "heat waves" has been analyzed considering the persistence of temperatures higher than the 90-th percentile for 5 consecutive days; analogously, the occurrence of "cold wave" has been found out considering the persistence of temperatures lower than the 10-th percentile for 5 consecutive days. Results indicate that in the last 20 years the number of heat waves has significantly increased with respect to the previous period, while an increasing of the cold waves has not been enhanced.

  7. 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 temperature rise in early spring immediately after dormancy release, likely brought forward the flowering date of cherry blossom. We derived a thermal time-based flowering model from this analysis and used it to predict the flowering dates of forsythia and cherry blossom in 2014. The root mean square error for the prediction was within 2 days from the observed flowering dates in both species, showing a feasibility of prediction under the changing climate.

  8. Trends in summer extreme temperatures over the Iberian Peninsula using nonurban station data

    NASA Astrophysics Data System (ADS)

    Acero, F. J.; García, José Agustín.; Gallego, María. Cruz; Parey, Sylvie; Dacunha-Castelle, Didier

    2014-01-01

    Heat wave event trends over the Iberian Peninsula (IP) are studied using extreme value theory, specifically the peaks-over-threshold (POT) approach. Summer (June-August) daily temperature records from 20 observatories regularly distributed over Iberia in places far from urban effects were available for the common period 1961-2010. Heat waves are defined as days occurring above the 95th percentile of the temperature distribution, considering both maximum (Tmax) and minimum (Tmin) temperatures. These events were identified using a "run declustering" scheme to select independent extreme events exceeding the threshold. Also, the dates of occurrence of the independent events were fitted to a Poisson process. Trends in the following parameters were studied: the scale parameter of the POT approach, the Poisson intensity, mean, return level period, and low (25th percentile) and high (75th percentile) values. The optimal trends in the Poisson intensity considering both Tmax and Tmin show a major increase in the occurrence of heat waves. Also, the rise in the return level trend was less than that in the mean of Tmin and Tmax, and the analysis of the values of Tminand Tmax showed a greater increasing trend in the low values (25th percentile) than in the high values (75th percentile), especially for Tmax, leading to a decrease in the variance. Over the IP, temperature extremes are increasing but not as much as the mean because the variance is tending to decrease. This highlights the important role of variance in the evolution of extremes.

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

    SciTech Connect

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

    2012-10-15

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

  10. 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.

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

    PubMed

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

    2015-06-25

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

  12. 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.

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

    NASA Astrophysics Data System (ADS)

    Mondal, Arun; Khare, Deepak; Kundu, Sananda

    2015-10-01

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

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

    E-print Network

    Haran, Murali

    , ancient analog for modern global warming [e.g., Zachos et al., 2001]. The PETM had a wide range of impacts! "! A statistical interpretation of surface ocean temperature trends during the Paleocene 08544, USA c Department of Statistics, Pennsylvania State University, University Park, PA 16802, USA d

  15. 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.

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

    E-print Network

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

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

    NASA Astrophysics Data System (ADS)

    Schliesser, Jacob M.; Woodfield, Brian F.

    2015-01-01

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

  20. Relationships between ten-year trends of tropospheric ozone and temperature over Taiwan.

    PubMed

    Hsu, Kuang-Jung

    2007-03-01

    The analyses of ten-year ozonesonde observations from 1993 till 2002, over Taipei, Taiwan show influences of climate change. Despite huge increases in its precursor emissions in this region, there were little variations in tropospheric ozone. Results indicate a warmer troposphere, a statistically insignificant rising tropopause, 79+/-206 m per decade, and decreasing tropopause temperature at -1.0+/-0.89 K per decade. The derived mean tropospheric ozone is 40.58+/-10.99 DU, and has a statistically insignificant small trend of -0.78+/-1.7 DU per decade. The derived ten-year vertical trends of temperature and ozone are inversely correlated with each other from the middle troposphere up to the lower stratosphere. The averaged monthly vertical temperature trends show a generally warmer middle troposphere. The tropospheric ozone monthly trend has small increases only in the lower troposphere during winter and spring. Strong decreases occur in summer, from the surface up into the stratosphere. For ozone variation, results suggest that influences of climate forcing are stronger than those from precursor increases. More frequent and/or intense convection in summer and other climate-induced effects may contribute to the less than expected ozone observed in the troposphere. PMID:17287012

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

    USGS Publications Warehouse

    Jastram, John D.; Rice, Karen C.

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Savi?, Stevan; Milovanovi?, Boško; Lužanin, Zorana; Lazi?, Lazar; Dolinaj, Dragan

    2015-08-01

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

  3. 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.

  4. Long term trends in the sea surface temperature of the Black Sea

    NASA Astrophysics Data System (ADS)

    Shapiro, G. I.; Aleynik, D. L.; Mee, L. D.

    2010-01-01

    There is growing understanding that recent deterioration of the Black Sea ecosystem was partly due to changes in the marine physical environment. This study uses high resolution 0.25° climatology to analyze sea surface temperature variability over the 20th century in two contrasting regions of the sea. Results show that the deep Black Sea was cooling during the first three quarters of the century and was warming in the last 15-20 years; on aggregate there was a statistically significant cooling trend. The SST variability over the Western shelf was more volatile and it does not show statistically significant trends. The cooling of the deep Black Sea is at variance with the general trend in the North Atlantic and may be related to the decrease of westerly winds over the Black Sea, and a greater influence of the Siberian anticyclone. The timing of the changeover from cooling to warming coincides with the regime shift in the Black Sea ecosystem.

  5. Long term trends in the sea surface temperature of the Black Sea

    NASA Astrophysics Data System (ADS)

    Shapiro, G. I.; Aleynik, D. L.; Mee, L. D.

    2010-05-01

    There is growing understanding that recent deterioration of the Black Sea ecosystem was partly due to changes in the marine physical environment. This study uses high resolution 0.25° climatology to analyze sea surface temperature variability over the 20th century in two contrasting regions of the sea. Results show that the deep Black Sea was cooling during the first three quarters of the century and was warming in the last 15-20 years; on aggregate there was a statistically significant cooling trend. The SST variability over the Western shelf was more volatile and it does not show statistically significant trends. The cooling of the deep Black Sea is at variance with the general trend in the North Atlantic and may be related to the decrease of westerly winds over the Black Sea, and a greater influence of the Siberian anticyclone. The timing of the changeover from cooling to warming coincides with the regime shift in the Black Sea ecosystem.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  7. 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.

  8. 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.

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

    NASA Astrophysics Data System (ADS)

    Yao, Junqiang; Chen, Yaning

    2015-05-01

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

  10. 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.

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

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

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

  12. 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.

  13. 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.

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

    NASA Astrophysics Data System (ADS)

    Gröcke, D.; Ufnar, D.; Beddows, P. A.

    2007-12-01

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

  15. 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 of springtime precipitation over southeastern China and downward trend of summertime precipitation over northern China are attributable to the warming trend of the ENSO-like mode. The recent frequent summertime floods over central eastern China are linked to the warming trend of SSTs over the warm pool and Indian Ocean.

  16. 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 >820?C. The lowest temperature periphery of the hotspot is characterized by sillimanite + muscovite + K-feldspar + minor garnet and reached a maximum temperature of 650?C. Bulk garnet ages from samples within the hotspot range significantly from at least 400.0 × 2.5 Ma to 352.7 × 1.8 Ma with the youngest ages associated with the lower temperature samples. This collection of ages indicates a prolonged period (~50 Ma) of >650?C temperatures interspersed by period(s) of garnet growth. Zoned garnet geochronology will help reveal whether garnet growth and related heating was continuous or episodic. Further south, in Phillipston, MA, zoned garnet geochronology performed on a 2.5 cm diameter garnet porphyroblast indicates garnet growth spanning 389 - 363 Ma, reaching peak temperatures at the end of that time span of 920-940?C, followed by a younger event recorded in smaller 1-3mm garnet crystals at 351 Ma (which may also reflect resetting of the earlier event), reaching similar temperatures of 920-960?C. These temperatures were obtained by Zr-in-rutile thermometry performed on rutile inclusions within the garnet. Even farther south, in the UHT zone around Willington, CT, temperatures of at least 1000?C were determined using Zr-in-rutile thermometry on rutile inclusions in garnet and reintegration of ternary feldspar compositions (Ague et al., 2013; Geology). The garnet age for a representative UHT sample from this site is 340.3 × 1.7 Ma. The geochronologic data presented here indicates a prolonged period of UHT/HT garnet growth within the Central Maine Terrane, beginning at ~400 Ma in Bristol, NH and ending at ~340 Ma in Willington, CT. Peak temperatures are >820?C in NH, >950?C in MA, and ~1000?C in CT, resulting in a regional pattern of increasing temperature with decreasing age from north to south across this 250 km long region.

  17. Determination of Equilibrium Dissolution Temperatures for Linear Polyethylene Using the Non-linear Hoffman-Weeks Approach

    NASA Astrophysics Data System (ADS)

    Marand, Herve

    2003-03-01

    This presentation focuses on the determination of equilibrium dissolution temperatures, Td, for linear polyethylene (PE) in different solvents using the MX approach. We demonstrated,[1] in the context of the Lauritzen-Hoffman surface nucleation theory, that as a result of the intrinsically non-linear dependence of melting temperature, Tm', on crystallization temperature, Tx, the equilibrium melting temperature, Tm, cannot be obtained through the Hoffman-Weeks approach, but can be determined using a non-linear (MX) analysis. This technique has been applied to the case of it-PP, s-PP and PEO, to name just a few, and is now extended to solution crystallization in the case of PE. Using data from Nakajima et al.[2], we show that PE's equilibrium dissolution temperatures, Td, obtained by the MX approach are consistently about 8 to 10 K higher than these obtained using the linear extrapolation, but are in excellent agreement with both the dissolution temperatures recorded for extended chain crystals and the Td values obtained using the Gibbs-Thompson analysis. Thus, these results provide further evidence of internal consistency for the LH theory, and cast further doubts on Strobl's four-state crystallization model. [1] Marand et al. Macromolecules 31, 8219 (1998) [2] Nakajima et al. Kolloid-Z. u. Z. Polym. 222(2), 124 (1968)

  18. 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 temperature and humidity dependence in the vegetation grow. This approach also allows defining zones of anthropogenic impact and dynamics of reclaimed after natural and anthropogenic influences. This work was partly supported by the Russian Foundation for Basic Research, project ? 13-06-00060

  19. 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. PMID:23873281

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. 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 ∼4 K at 70 hPa), with a strong dynamical response during Pinatubo partially masking the aerosol heating.

  5. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  8. 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

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  10. 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 increasing (reducing) with significance in almost all regions. "Região dos Lagos" has the most significant trends of increasing in temperature, thereby influencing the local production of salt and alkaline minerals in medium and long term. The goal of this research is, through the analysis of results, support studies of vulnerability and adaptation to climate change scenarios in Rio de Janeiro State.

  11. 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 crossover between lower atmospheric heating and upper atmospheric cooling that is located at about 90 hPa in the tropics and 30-40 hPa in the polar regions. This results from the combination of continuing increases in greehouse gases and recovery from ozone depletion.

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  14. Fluctuating temperatures and ectotherm growth: distinguishing non-linear and time-dependent effects.

    PubMed

    Kingsolver, Joel G; Higgins, Jessica K; Augustine, Kate E

    2015-07-01

    Most terrestrial ectotherms experience diurnal and seasonal variation in temperature. Because thermal performance curves are non-linear, mean performance can differ in fluctuating and constant thermal environments. However, time-dependent effects--effects of the order and duration of exposure to temperature--can also influence mean performance. We quantified the non-linear and time-dependent effects of diurnally fluctuating temperatures for larval growth rates in the tobacco hornworm, Manduca sexta L., with four main results. First, the shape of the thermal performance curve for growth rate depended on the duration of exposure: for example, optimal temperature and thermal breadth were greater for growth rates measured over short (24?h during the last instar) compared with long (the entire period of larval growth) time periods. Second, larvae reared in diurnally fluctuating temperatures had significantly higher optimal temperatures and maximal growth rates than larvae reared in constant temperatures. Third, for larvae maintained at three mean temperatures (20, 25 and 30°C) and three diurnal temperature ranges (±0, ±5 and ±10°C), diurnal fluctuations had opposite effects on mean growth rates at low versus high mean temperature. Fourth, both short- and long-term thermal performance curves yielded poor predictions of the non-linear effects of fluctuating temperature on mean growth rates (compared with our experimental results) at higher mean temperatures. Our results suggest caution in using constant temperature studies to model the consequences of variable thermal environments. PMID:25987738

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

    USGS Publications Warehouse

    Madej, Mary Ann

    2011-01-01

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

  16. Projected trends in mean, maximum, and minimum surface temperature in China from simulations

    NASA Astrophysics Data System (ADS)

    You, Qinglong; Min, Jinzhong; Fraedrich, Klaus; Zhang, Wei; Kang, Shichang; Zhang, Ling; Meng, Xianhong

    2014-01-01

    This study examines the projected characteristics of mean temperature (Tmean), maximum temperature (Tmax) and minimum temperature (Tmin) in China during 2006-2100 from simulations of MPI-ESM-LR model within the Coupled Model Intercomparison Project Phase 5 (CMIP5). Periods of 2011-2040 and 2061-2090 are concentrated on the analysis under the three representative concentration pathway (RCP) scenarios: a high emission scenario (RCP8.5), a midrange mitigation emission scenario (RCP4.5), and a low emission scenario (RCP2.6). Under RCP8.5, the Tmean, Tmax and Tmin show pronounced warming with the annual rates of 0.43 °C/decade, 0.42 °C/decade, 0.45 °C/decade during 2011-2040, and 0.72 °C/decade, 0.70 °C/decade, 0.76 °C/decade during 2061-2090, which pronouncedly contributed by winter. Under RCP4.5, the Tmean, Tmax and Tmin display consistent increases during 2011-2040 with the trends of 0.29 °C/decade, 0.29 °C/decade, 0.30 °C/decade on the annual basis, respectively, and the increases calm down for Tmean, Tmax and Tmin up to 0.14 °C/decade during 2061-2090. Under RCP2.6, the Tmean, Tmax and Tmin demonstrate positive trends during 2011-2040 with the annual rates of 0.26 °C/decade, 0.28 °C/decade, 0.25 °C/decade, respectively, and turn to negative afterwards. Moreover, the annual and seasonal Tmean, Tmax and Tmin are in agreement with the concentration of greenhouse gases in the atmosphere and reflect the variability of the radiative forcing trajectories in the RCP. For the spatial patterns, the northeastern China and the Tibetan Plateau are more sensitive and susceptible to climate change in future emission scenarios. It fails to capture the asymmetric trends for Tmax and Tmin projections, which do exist in the observations on the regional and global scales. This suggests that the projections have uncertainties in the models, and an understanding of causes is essential to improve the accuracies.

  17. Thrust characteristics of a linear oscillatory actuator at a low temperature

    SciTech Connect

    Aoki, Akio; Watada, Masaya; Torii, Susumu; Yamane, Kimitaka; Ebihara, Daiki

    1998-07-01

    The low temperature liquids pump is expected to be used in the many kinds of fields. The low temperature liquids pump must obtain a larger thrust and minimal heating of the low temperature liquid in the tank, and is applied to a liquid hydrogen pump and a liquid natural gas pump. A liquid hydrogen pump with the LOA is used for automobiles fueled by a liquid hydrogen. This paper reports the static thrust characteristics of a linear oscillatory actuator at low and normal temperatures. The static thrust with respect to position was measured with a variable exciting current. Normal temperature (25 C) was maintained using water cooling, and low temperature was offered using liquid nitrogen. The detent force at low temperature was larger than that at normal temperature. For magnetomotive forces at 5 kA and 3 kA, the static thrust of low temperature was less than that at normal temperature.

  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. 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 preserved in the sediment record of Lake Schreventeich reflect summer surface water temperatures. As N2-fixing heterocystous cyanobacteria are widespread in present-day freshwater and brackish environments, we conclude that the distribution of HGs in sediments may allow for the reconstruction of surface water temperatures of modern and potentially ancient lacustrine settings.

  20. 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 heterocystous cyanobacteria are widespread in present-day freshwater and brackish environments, we conclude that the distribution of HGs in sediments may allow the reconstruction of surface water temperatures of modern and potentially ancient lacustrine settings.

  1. Solar wind proton temperature anisotropy: Linear theory and WIND/SWE observations

    E-print Network

    Richardson, John

    Solar wind proton temperature anisotropy: Linear theory and WIND/SWE observations Petr Hellinger,1/SWE observations (Kasper et al., 2006) of bkp and T?p/Tkp (where bkp is the proton parallel beta and T?p and Tkp are the perpendicular and parallel proton temperatures, respectively; here parallel and perpendicular indicate

  2. 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

    2015-06-01

    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.

  3. 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 due to bleaching in 1983 and 1998, and increasing variance in anomalies (both positive and negative) the E-Pacific presently maintains an upward trend in coral cover and colony frequency. In the Red Sea , variance in anomalies increased but exclusively towards positive values. In the Gulf, variance declined towards stronger and only positive anomalies. In both regions, this raised thermal envelope is associated with reef decline. This is most dramatic in the Gulf, with six bleaching events since 1996, but also obvious in the Red Sea (bleaching in 1998, 2005 and 2010). Both Gulf and Red Sea suffer also from other mortality factors, such as diseases and predator outbreaks. Decline in reef health is therefore not uniquely linked to bleaching, but other mortality factors are also linked to changes in the thermal envelope. Chronic effects of increased average temperatures seem to define a reef trajectory more closely than the effects of individual, albeit strong, episodic disturbances.

  4. 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.

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

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    2013-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  7. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

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

    E-print Network

    Robertson, Robin

    Long-term Temperature Trends in the Deep Waters of the Weddell Sea Robin Robertson*, Martin Visbeck November 28, 2001 #12;Long-term Temperature Trends in the Deep Waters of the Weddell Sea 2 Abstract Warming Water (WSDW) potential temperatures between 1500 and 3500 m were warmer in the 1990's than in the 1970's

  10. Long-term trends in dynamic height and sea surface temperature

    SciTech Connect

    Barnett, T.P.

    1983-04-01

    Secular changes in the density structure of the upper ocean are investigated to see if they can explain the apparent rise in sea level observed along the continental margins of the world's oceans. The time rate of change of dynamic height is estimated to be -0.8 dyn cm/cent, a value that is indistinguishable statistically from 0. Further, the distribution of individual values entering the grand average are distributed normally to a high degree of approximation. Assuming the change in relative sea level is real, then it could be due to either melting of the polar caps or warming of the upper ocean. Warming, since the turn of the century, of the magnitude suggested in much of the literature would have been detectable in the density structure of the upper ocean. This signal was not seen in the current analysis. A more modest warming, allowing for instrumental biases over the last 50 years and/or melting of the polar caps by just enough to give the observed change in relative sea level would have signatures in the upper ocean density field that would barely be detectable in the current study. A combination of warming and melting together should have had a signal that was marginally detectable. This latter signal was not observed. Comparison of historical sea surface temperature (SST) trends from ship-of-opportunity reports and hydrographic data suggest instrumental bias can account for roughly one-half of the apparent increase in ocean temperature since 1899. Differing measurement methods (buckets vs injection temperature) may also be partially responsible for an apparent discontinuity in the SST series in the early 1940's.

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

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    Detection of climate change requires a network of stable ground-based long-term measurements. Building upon earlier work, we first explore requirements of such measurements (such as maximum random uncertainty and sampling frequency) to ensure a minimum random uncertainty in monthly mean temperatures and to ensure effective detection of trends. In agreement with previous work we find that only for individual measurement random uncertainties > 0.2 K does the measurement random uncertainty start to contribute significantly to the random uncertainty in the monthly mean. For trend analysis, we find that the quality of the trend determination is only compromised when the measurement random uncertainty exceeds 2 K and measurements are made just once or twice a month. In the second part of the study we provide guidance on how to most effectively design a measurement network. To this end we developed a method to objectively identify the optimal location of sites for detecting projected trends in upper-air temperatures and total column ozone in the shortest possible time. This is done by first estimating the spatial distribution of the minimum length of time during which measurements have to be made in order to detect projected trends in temperature and ozone. This quantity is calculated from the unforced variance in the signal and the degree of autocorrelation, both estimated from historical data sets and assumed not to change in the future, and the projected trends as estimated from chemistry-climate models. The optimal site locations are then selected by an iterative procedure based on the minimum time required to detect a trend and a minimal distance between different measurement sites. While the optimal sites identified here result from our use of only one of a wide range of objective strategies, these results provide additional incentives for initiating measurement programmes at these sites or, if already in operation, to continue to be supported.

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

    PubMed Central

    Chen, Chun-Chi; Chen, Hao-Wen

    2013-01-01

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

  15. 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

    2015-01-01

    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

    NASA Astrophysics Data System (ADS)

    Lin, Yong; Franzke, Christian L. E.

    2015-08-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

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

    NASA Astrophysics Data System (ADS)

    Aumann, H. H.; Ruzmaikin, A.

    2014-12-01

    Making unbiased measurements of trends in the surface temperatures, particularly on a gobal scale, is challenging: While the non-frozen oceans temperature measurements are plentiful and accurate, land and polar areas are much less accurately or fairly sampled. Surface temperature deduced from infrared radiometers on polar orbiting satellites (e.g. the Atmospheric Infrared Sounder (AIRS) at 1:30PM, the Interferometer Atmosphere Sounding Interferometer (IASI) at 9:30 AM and the MODerate resolution Imaging Spectro-radiometer (MODIS) at 1:30PM), can produce what appear to be well sampled data, but dealing with clouds either by cloud filtering (MODIS, IASI) or cloud-clearing (AIRS) can create sampling bias. We use a novel method: Random Nadir Sampling (RNS) combined with Probability Density Function (PDF) analysis. We analyze the trend in the PDF of st1231, the water vapor absorption corrected brightness temperatures measured in the 1231 cm-1 atmospheric window channel. The advantage of this method is that trends can be directly traced to the known, less than 3 mK/yr trend for AIRS, in st1231. For this study we created PDFs from 22,000 daily RNS from the AIRS and IASI data. We characterized the PDFs by its daily 90%tile value, st1231p90, and analysed the statistical properties of the this time series between 2002 and 2014. The method was validated using the daily NOAA SST (RTGSST) from the non-frozen oceans: The mean, seasonal variability and anomaly trend of st1231p90 agree with the corrsponding values from the RTGSST and the anomaly correlation is larger than 0.9. Preliminary results (August 2014) confirm the global hiatus in the increase of the globally averaged surface temperatures between 2002 and 2014, with a change of less than 10 mK/yr. This uncertainty is dominated by the large interannual variability related to El Niño events. Further insite is gained by analyzing land/ocean, day/night, artic and antarctic trends. We observe a massive warming trend in the Artic between 2002 and 2007, which has since level off, but no significant trend in the Antarctic. The AIRS results since 2002 are confirmed by IASI data since 2007. 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.

  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. Comparison of trends and low-frequency variability in CRU, ERA-40, and NCEP/NCAR analyses of surface air temperature

    NASA Astrophysics Data System (ADS)

    Simmons, A. J.; Jones, P. D.; da Costa Bechtold, V.; Beljaars, A. C. M.; KâLlberg, P. W.; Saarinen, S.; Uppala, S. M.; Viterbo, P.; Wedi, N.

    2004-12-01

    Anomalies in monthly mean surface air temperature from the 45-Year European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-40) and the first National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis are compared with corresponding values from the Climatic Research Unit (CRU) CRUTEM2v data set derived directly from monthly station data. There is mostly very similar short-term variability, especially between ERA-40 and CRUTEM2v. Linear trends are significantly lower for the two reanalyses when computed over the full period studied, 1958-2001, but ERA-40 trends are within 10% of CRUTEM2v values for the Northern Hemisphere when computed from 1979 onward. Gaps in the availability of synoptic surface data contribute to relatively poor performance of ERA-40 prior to 1967. A few highly suspect values in each of the data sets have also been identified. ERA-40's use of screen-level observations contributes to the agreement between the ERA-40 and CRUTEM2v analyses, but the quality of the overall observing system and general character of the ERA-40 data assimilation system are also contributing factors. Temperatures from ERA-40 vary coherently throughout the boundary layer from the late 1970s onward, in general, and earlier for some regions. There is a cold bias in early years at 500 hPa over the data-sparse southern extratropics and at the surface over Antarctica. One indicator of this comes from comparing the ERA-40 analyses with results from a simulation of the atmosphere for the ERA-40 period produced using the same model and same distributions of sea surface temperature and sea ice as used in the ERA-40 data assimilation. The simulation itself reproduces quite well the warming trend over land seen in CRUTEM2v and captures some of the low-frequency variability.

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

    E-print Network

    Haba, Z

    2015-01-01

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

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

    E-print Network

    Z. Haba

    2015-04-14

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

  3. The Hawking-Unruh Temperature and Damping in a Linear Focusing Channel

    E-print Network

    McDonald, Kirk

    The Hawking-Unruh Temperature and Damping in a Linear Focusing Channel Kirk T. McDonald Joseph Henry Laboratories, Princeton University, Princeton, NJ 08544 (January 30, 1998) Abstract The Hawking by Hawking [1], and applied to accelerated particles (with the neglect of gravity) by Unruh [2]. Hawking

  4. 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.

  5. Temperature dependence of linear electrooptic coefficients r 113 and r 333 in lithium niobate

    NASA Astrophysics Data System (ADS)

    Górski, P.; Ledzion, R.; Bondarczuk, K.; Kucharczyk, W.

    2008-03-01

    A new method of determination of individual linear electrooptic coefficients is proposed. The technique is based on the dynamic polarimetric measurements and takes into consideration the temperature dependences of ordinary and extraordinary refractive indices. Results obtained for the electrooptic coefficients r113 and r333 in LiNbO3 are presented. The coefficients are found to increase significantly within the considered temperature range 25-200°C. The temperature dependences of the intrinsic coefficients m113 and m333, defined in terms of the induced polarisation, are considered as well.

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

  8. 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.

  9. 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.

    2015-05-01

    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 makes the spatial structures of precipitation trends more similar to those simulated by CMIP5 historical full forcing experiments particularly in the context of zonal-mean results. This also confirms that in spite of the PDO effect specifically on regional scales, the anthropogenic GHG signals are still discernible in observed precipitation during the time period. Following the increase of GHG, precipitation tends to increase roughly along the climatological ITCZ and decrease south of the equator and in the subtropics of both hemispheres.

  10. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

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

  12. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2008-09-01

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

  14. A parametric study of non-linear evolution of tearing mode with temperature anisotropy

    NASA Astrophysics Data System (ADS)

    Shinohara, Iku; Fujimoto, Masaki

    2013-04-01

    We have studied the non-linear evolution of the tearing instability with temperature anisotropy, T?-T-- by using a 2-D full kinetic simulation. As predicted by the linear-theory, e.g. Chen and Palmadesso (1984), Quest et al. (2010), the growth rate of the tearing mode increases as higher anisotropy, T?-T--. Two parametric studies have been done: (i) changing the current sheet thickness with the fixed anisotropy ratio, and (ii) changing the anisotropy ratio and the ion-electron temperature ratio with a fixed current sheet thickness. As a result, we found that event in a thick current sheet case, D-?i = 4 (D is the current sheet thickness, and ?i is the ion inertia length.), fast growth emerges at the non-linear stage and the growth rate is almost proportional to D-?i and that the growth rate and saturation level at the non-linear stage are independent on parameters once the explosive growth starts. The most impressible results are those (1) electron anisotropy plays important role to push the tearing mode into the non-linear stage and (2) there exists a threshold value of the ion-electron temperature ratio for enabling the explosive growth as the results of Tanaka et al. (2004). We think that these facts may be a big hint to solve the triggering mechanism of magnetic reconnection. We will show the results of our parametric study and discuss possible physical meaning of the threshold value for the explosive evolution.

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

    PubMed Central

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

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Sherstiukov, A.

    2013-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  18. Linear evolution of the vortex induced by localized temperature disturbance in stratified shear flow (Russian Title: ???????? ???????? ?????, ????????????? ????????? ??????????? ??????????? ? ?????????????????? ????????? ???????)

    NASA Astrophysics Data System (ADS)

    Shukhman, Ilia G.; Weiss-Tewner, Shoshana; Cohen, Jacob

    2015-06-01

    We study the combined effect of the shear flow velocity and its (stable) vertical stratification on the evolution of the three-dimensionally localized vortical disturbance induced by the initial temperature perturbation embedded at the initial time into a local region of the flow. Small geometric scales of perturbations compared to the characteristic scales of velocity and temperature variation of the background flow allow to consider vertical gradients of the horizontal velocity and temperature to be not dependent on the coordinates. Assuming a disturbance sufficiently weak, we use linear theory to calculate fields of vorticity and temperature. The problem is solved analytically using a three-dimensional Fourier transform of the basic set of equations and further transition to a Lagrange variables in the Fourier space. It is shown that the growth of the intensity of the vortex (a measure of which are enstrophy and circulation) is obliged to both stratification and shear. However, the character of this growth (monotonous or oscillating) depends on what of two factors dominates. In the case where the dissipation effects are negligible, enstrophy grows indefinitely (in the framework of the linear theory), but dissipative factors (viscosity and thermal diffusivity) modified this growth and make it only transient, so that eventually the perturbation decays. Perturbation domain stretches along the direction of flow, but its vertical and horizontal movement as a whole in the framework of the linear theory doesn't occur, since it is the nonlinear effect. Nonlinear evolution of the vortex induced by temperature disturbance is considered in a separate paper.

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  20. Nucleon Properties in the Quantized Linear Sigma Model at Finite Temperature and Chemical Potential

    E-print Network

    H. M. Mansour; M. Abu-Shady

    2015-07-25

    The linear sigma model at finite temperature and chemical potential is systematically studied using the coherent-pair approximation, in which fully taking quantum of fields are included. The expectation value of the chiral Hamiltonian density is minimized and the resulting equations for the nucleon are solved. The qualitative features of the quantized sigma and pion fields are strong sensitive to the change of temperature and baryonic chemical potential and are in agreement with the mean-field approximation calculations. It is noticed that the nucleon mass increases with increasing coherence parameter. In addition, the nucleon mass increases with increasing temperature and the baryonic chemical potential and then it decreases at higher values of the temperature and baryonic chemical potential. The obtained results show that the mean-square radius of the proton and the neutron increase with increasing temperature or the baryonic chemical potential and that the pion-nucleon coupling constant decreases with the temperature or chemical potential. We conclude that the coherent-pair approximation successfully give better description of the nucleon properties at finite temperature and baryonic chemical potential

  1. 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 frequency variability responds to 55-75% of the total variability away from the continental borders. The seasonal frequency is important in the CBM region and in the inner of ZR (25%, 40%, 35%). The WSC variance was mostly explained by high frequencies (70%), low frequencies explained between 10% and 15%, at latitudes lower than 20°S, in the Argentinean continental slope and in the Agulhas Leakage. The EOF analysis were performed on the high and low frequencies components of each variable. The results will be presented in the poster.

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

    SciTech Connect

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

    2015-01-21

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

  3. Decadal-Scale Temperature Trends in the Southern Hemisphere Ocean SARAH T. GILLE

    E-print Network

    Griesel, Alexa

    . Warming is concentrated within the Antarctic Circumpolar Current (ACC). On a global scale, this warming a statistically significant warming trend during the same time period (e.g., Doran et al. 2002; Chapman and Walsh m of the Southern Hemisphere ocean has warmed substantially during this time period at all depths

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

    NASA Astrophysics Data System (ADS)

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

    2009-05-01

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

  5. 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 water of North Sea origin occur sporadically and transport high-saline water into the deep layers of the Baltic Sea. These inflow events occur when high pressure over the Baltic region with easterly winds is followed by several weeks of strong westerly winds; changes in the inflow activity are related to the frequency of deep cyclones and their pathways over the Baltic area. Major inflows are often followed by a period of stagnation during which saline stratification decreases and oxygen deficiency develops in the deep basins of the central Baltic. Major inflows are usually of barotropic character. They normally occur during winter and spring and transport relatively cold, salty and oxygen-rich waters to the deep basins. Since 1996, another type of inflows have been observed during summer or early autumn. These inflows are of baroclinic character and transport high-saline, but warm and low-oxygen water into the deep layers of the Baltic Sea. Event-like water exchange and mixing anomalies, driven by specific atmospheric forcing patterns like sequences of deep cyclones, occur also in other parts of the Baltic Sea.

  6. 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.

  7. Twelve-month running trends from Earth Radiation Budget Satellite (ERBS) active-cavity radiometric measurements and global surface temperatures

    NASA Astrophysics Data System (ADS)

    Pandey, Dhirendra K.; Lee, Robert B., III; Paden, Jack; Bush, Kathryn A.; Snyder, Dianne; Wilson, Robert S.; Banks, Waldena; Al-Hajjah, Aiman; Thomas, Susan

    2004-02-01

    Four earth-viewing nonscanning active cavity radiometers of the ERBS (Earth Radiation Budget Satellite) have been measuring the radiation arising from the earth-atmosphere system since its" launch day, October 5, 1984. The ERBS spacecraft was placed in a non-sun-synchronous trajectory inclined at 57°. Two radiometers out of four, namely the wide field-of-view total (WFOV-T) radiometer which measures the radiation in the total spectral band of 0.2 - 100 ?m, and the wide-field-of-view shortwave (WFOV-SW) radiometer measures the Earth"s reflected radiation in the wavelength region of 0.2 - 5 ?m were used in this study. These sensors were calibrated continuously by observing the in-flight internal black bodies as well as the Sun every two weeks. The WFOV-T channel was found very stable within 0.1%. The monthly flux values of the ERBS nonscanning active cavity radiometers at satellite altitude and the corresponding NCDC (National Climatic Data Center) global surface temperature data for the period of fifteen years (1985-1999) were used in this paper. The effect of Mt. Pinatubo eruption is very clearly noticeable in the running trends of both WFOV-T and WFOV-SW radiometric measurements. Further the resulting twelve month running trends derived from the outgoing longwave radiation was found to follow the twelve month running trend determined from the global surface temperature data set. Both trends are real and increasing. The "global-cooling-like" event caused by the Mt. Pinatubo eruption was also found under both day and nighttime conditions.

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

    E-print Network

    D. J. G. Pearce; L. Giomi

    2015-11-16

    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 form 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 numerical simulations, 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.

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

    SciTech Connect

    Moradi, S.; Anderson, J.

    2012-08-15

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

  10. 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).

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

    E-print Network

    Trends in the Surface Meridional Temperature Gradient Alix I. Gitelman a , James S. Risbey b's climate. Defining an MTG index here as the difference in surface temperature between the 30 ffi --35 ffi N in earth's global average temperature (Jones et al., 1986a; Jones et al., 1986b; Hansen and Lebedeff, 1987

  12. 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.

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

    E-print Network

    Polvani, Lorenzo M.

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

  14. Spatio-temporal trend analysis of air temperature in Europe and Western Asia using data-coupled clustering

    NASA Astrophysics Data System (ADS)

    Chidean, Mihaela I.; Muñoz-Bulnes, Jesús; Ramiro-Bargueño, Julio; Caamaño, Antonio J.; Salcedo-Sanz, Sancho

    2015-06-01

    Over the last decades, different machine learning techniques have been used to detect climate change patterns, mostly using data from measuring stations located in different parts of the world. Some previous studies focus on temperature as primary variable of study, though there have been other works focused on precipitation or even wind speed as objective variable. In this paper, we use the self-organized Second Order Data Coupled Clustering (SODCC) algorithm to carry out a spatio-temporal analysis of temperature patterns in Europe. By applying the SODCC we identify three different regimes of spatio-temporal correlations based on their geographical extent: small, medium, and large-scale regimes. Based on these regimes, it is possible to detect a change in the spatio-temporal trend of air temperature, reflecting a shift in the extent of the correlations in stations in the Iberian Peninsula and Southern France. We also identify an oscillating spatio-temporal trend in the Western Asia region and a stable medium-scale regime affecting the British Isles. These results are found to be consistent with previous studies in climate change. The patterns obtained with the SODCC algorithm may represent a signal of climate change to be taken into account, and so the SODCC could be used as detection method.

  15. 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.

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

    NASA Astrophysics Data System (ADS)

    Hall, D. K.; Comiso, J. C.; Shuman, C. A.; Koenig, L.; DiGirolamo, N. E.

    2011-12-01

    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 in the extent of melt and 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. Twelve-year trends in IST are compared with in-situ data, and climate data from the Modern Era Retrospective-Analysis for Research and Applications (MERRA) Reanalysis. Hall, D.K., J.C. Comiso, N.E. DiGirolamo, C.A. Shuman, J. Key and L.S. Koenig, submitted for journal publication: A Satellite-Derived Climate-Quality Data Record of the Clear-Sky Surface Temperature of the Greenland Ice Sheet.

  17. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

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

  19. Implicit Integration by Linearization for High-Temperature Inelastic Constitutive Models

    NASA Astrophysics Data System (ADS)

    Akamatsu, Masafumi; Nakane, Kazuhiko; Ohno, Nobutada

    In this study, a linearization method is used to develop an implicit integration scheme for a class of high-temperature inelastic constitutive models based on non-linear kinematic hardening. A non-unified model is first considered in which the inelastic strain rate is divided into transient and steady parts driven, respectively, by effective stress and applied stress. By discretizing the constitutive relations using the backward Euler method, and by linearizing the resulting discretized relations, a tensor equation is derived to iteratively achieve the implicit integration of constitutive variables. The implicit integration scheme developed is shown to be applicable to a unified constitutive model in which back stress evolves due to static and dynamic recoveries in addition to strain hardening. The integration scheme is then programmed for a subroutine in a finite element code and applied to a lead-free solder joint analysis. It is demonstrated that the integration scheme affords quadratic convergence in the iterations even for considerably large increments, and that the non-unified and unified models give almost the same results in the solder joint analysis.

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

    PubMed

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

    2015-12-28

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

  1. 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.

  2. 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

    2015-05-01

    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.

  3. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2004-12-01

    In this study, trends of annual and seasonal surface air temperature time series were examined for 20 stations in Greece for the period 1955 2001, and satellite data for the period 1980 2001. Two statistical tests based on the least square method and one based on the Mann-Kendall test, which is also capable of detecting the starting year of possible climatic discontinuities or changes, were used for the analysis. Greece, in general, shows a cooling trend in winter for the period 1955 2001, whereas, summer shows an overall warming trend, however, neither is statistically significant. As a result, the overall trend of the annual values is nearly zero. Comparison with corresponding trends in the Northern Hemisphere (NH) shows that temperatures in Greece do not follow the intense warming trends. Satellite data indicate a remarkable warming trend in mean annual, winter and summer in Greece for the period 1980 2001, and a slight warming trend in annual, spring and autumn for the NH. Comparison with the respective trends detected in the surface air temperature for the same period (1980 2001) shows they match each other quite well in both Greece and the NH. The relationship between temperature variability in Greece and atmospheric circulation was also examined using correlation analysis with three circulation indices: the well-known North Atlantic Oscillation Index (NAOI), a Mediterranean Oscillation Index (MOI) and a new Mediterranean Circulation Index (MCI). The MOI and MCI indices show the most interesting correlation with winter temperatures in Greece. The behaviour of pressure and the height of the 500 hPa surface over the Mediterranean region supports these results.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    In the late twentieth century, the sub-thermocline waters of the southern tropical and subtropical Indian Ocean (IO) experienced a sharp cooling. This cooling has been previously attributed to an anthropogenic aerosol-induced strengthening of the global ocean conveyor, which transfers heat from the subtropical gyre latitudes toward the North Atlantic. From the mid-1990s the sub-thermocline IO experienced a rapid temperature trend reversal. In the context of understanding the causes of the sub-thermocline temperature changes, we use a suite of Coupled Model Intercomparison Project phase 5 (CMIP5) models forced with natural and anthropogenic radiative forcings and as well as individual forcing runs. We use these to: (i) examine whether the sub-thermocline cooling and/or rapid warming of the tropical/subtropical IO is anthropogenic or naturally forced; and (ii) assess future projections of the sub-thermocline temperatures in the mid twenty-first century from available model output. Results suggest that the late twentieth century sub-thermocline cooling of the southern IO was primarily driven by increasing anthropogenic aerosols and greenhouse gases. The models simulate a slow-down in the sub-thermocline cooling followed by a rapid warming towards the middle of the twenty-first century. The timing of the commencement of this warming appears dependent on the total change in anthropogenic aerosol levels, with models exhibiting a strong (weak) decline in future aerosols simulating a greater (weaker) magnitude of warming after the occurrence of peak aerosols. The role of greenhouse gases in forcing sub-thermocline temperature trends in the IO in the future remains to be determined. Despite this, it is clear is that as human generated aerosols continue to decline over the coming century, the subsurface ocean circulation will respond accordingly through an acceleration in the warming.

  6. 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.

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

    NASA Astrophysics Data System (ADS)

    Seliga, E.; Bošák, O.; Koštial, P.; Dvo?ák, 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.

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

    SciTech Connect

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

    1993-01-01

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

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

    SciTech Connect

    Easter, R.C. ); Peters, L.K. . Dept. of Chemical Engineering)

    1993-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  11. 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 from artifacts that need to be resolved in order to answer the question whether the large-scale flow and temperature field is sufficient to explain water entering the stratosphere.

  12. 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 approach, HOME). For precipitation, an additional test - RhTestV3 - was applied over the station data to ensure the homogeneity of the series. The analysis of the quality-controlled and homogenized maximum and minimum temperature series, shows an increase and statistically significant trend for the period 1934-2008. More precisely, the results are significant for both approaches (C3-SNHT and C-M) and for annual maximum temperature (0.12 and 0.10°C/decade, respectively), maximum summer temperature (0.25 and 0.17°C/decade, respectively), and minimum winter temperature (0.18 and 0.11°C/decade, respectively). The results were also obtained for the period 1971-2008. It is observed that the upward trend of the temperature has been reinforced in Andorra for this most recent period. Regarding precipitation, with the application of different tests, non-significant results for all the seasons and for the whole period (1934-2008) were obtained, so it cannot be concluded any increasing or decreasing trend. Nevertheless, preliminary results for the 1950-2008 period aim clearly towards a significant decrease of the annual total accumulation (-4.26mm/decade [being -7.80/-1.03, the confidence intervals at 95% level]), being especially relevant and also significant for the summer totals (-2.44 mm/decade [being -3.74/-1.13, the confidence intervals at 95% level]). The obtained trends for temperature agree with those obtained in Spain (Brunet et al., 2007), France (Spagnoli et al., 2002 and Maris et al., 2009) and Catalonia (Meteorological Service of Catalonia, 2008). Bibliography: - Brunet M, Jones PD, Sigró J, Saladié O, Aguilar E, Moberg A, Della-Marta PM, Lister D, Whalter A, López D. 2007. Temporal and spatial temperature variability and change over Spain during 1850-2005. Journal of Geophysical Research,, 112, D12117, doi:10.1029/2006JD008249 - Butlletí Anual d'Indicadors Climàtics, 2008 (BAIC,2008). Àrea de Climatologia, Servei Meteorològic de Catalunya. (http://www.meteo.cat) - Spagnoli B, Planton S, Mestre O, Déqué M, Moisselin, JM (2002). Detecting climate change

  13. 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…

  14. 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

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

    PubMed

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

    1999-08-01

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

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

    SciTech Connect

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

    2009-04-22

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

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

    SciTech Connect

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

    1980-10-01

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

  18. 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 warming and fall cooling rates. Trends in all of the parameters were examined after low-pass filtering using a 10-point convolution filter ( n=10 years) and regime shifts were identified using the sequential t-test analysis of regime shifts (STARS) method. The analysis shows some difference between regions in the timing of minimum SST with minima being reached 1 month earlier in the south (February) relative to more northern regions (March). Regional annual SST range decreased in a seaward direction. Amplitude of summer warming and the length of summer have shown fluctuations with recent years showing stronger warming and longer summers but generally not exceeding past levels. Overall, the difference in SST range, with recent larger values may be the most significant finding of this work. SST range changes have the potential to disrupt species important to local fisheries due to combinations of differing temperature tolerances, changes in reproduction potential, and changes in the distributional range of species.

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

    PubMed Central

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

    2013-01-01

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

  20. 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. PMID:22851349

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

    SciTech Connect

    Munz, Claus-Dieter . E-mail: claus-dieter.munz@iag.uni-stuttgart.de; Dumbser, Michael . E-mail: michael.dumbser@iag.uni-stuttgart.de; Roller, Sabine . E-mail: roller@hlrs.de

    2007-05-20

    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.

  2. 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.

  3. 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.

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

    PubMed

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

    2012-11-01

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

  5. 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.

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed

    Guin, Satya N; Biswas, Kanishka

    2015-04-28

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

  8. 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.

  9. 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 characteristics. Latest research results have demonstrated the great potential of the new technique to global climate monitoring and numerical weather prediction. With the newly launched six FORMOSAT-3 LEO satellites in 2006, thousands of high-quality, globally-distributed daily vertical profiles of refractivity, temperature and moisture have been obtained [Liou et al. 2007]. It is anticipated that GPS RO technique will play an important role in meteorological studies because of the significantly increased amount of atmospheric observations and improved data processing methodology. In this study, we use GPS RO data and collocated radiosonde data from three Australian weather observation stations (Casey, Davis and Mawson) to evaluate impacts of different collocation criteria (specifically, 100, 200 and 300 km spatial buffers and 1, 2 and 3 hour temporal buffers). Spatial and temporal variations in troposhperic temperatures over Antarctica are also investigated using the GPS RO data. Detailed analysis of refractivity and temperature profiles is presented and seasonal temperature variations in the troposphere are discussed. References Johanson, C. M., and Q. Fu, 2007: Antarctic atmospheric temperature trend patterns from satellite observations. Geophys. Res. Lett. 34, L12703, doi:10.1029/2006GL029108. Liou, Y.-A., A. G. Pavelyev, S. F. Liu, A. A. Pavelyev, N. Yen, C. Y. Huang, and C. J. Fong, 2007: FORMOSAT-3 GPS radio occultation mission: preliminary results. IEEE Trans. Geosci. Remote Sensing, 45(10), doi:10.1109/TGRS.2007.903365. Steig, E. J., D. P. Schneider, S.D. Rutherford, M. M. Mann, J. C. Comiso, and D. T. Shindell, 2009: Warming of the Antarctic ice-sheet surface since the 1957 International Geophysical Year. Nature 457, 22 January 2009, doi: 10.1038/nature07669. Turner, J., S.R. Colwell, G.J. Marshall, T.A. Lachlan-Cope, A.M. Carleton, P.D. Jones, V. Lagun, P.A. Reid, and S. Iagovkina, 2005: Antarctic climate change during the last 50 years. Int. J. Climatol. 25, 279-294. Turner, J., T. A. Lachlan-Cope, S. Colwell, G. J. Marshall, and W. M. Connolley, 2006: Signif

  10. Variations and Trends in Global and Arctic Surface Temperature and Forecasts of Global Temperature a Year Ahead, 2000-2010. (Invited)

    NASA Astrophysics Data System (ADS)

    Folland, C. K.; Kennedy, J.; Colman, A.; Knight, J.; Stott, P.; Smith, D.; Parker, D. E.

    2010-12-01

    We comment in some detail on the difficulties of correctly capturing recent Arctic warming accurately in global surface temperature data sets. We also discuss likely biases in modern sea surface temperature (SST) data worldwide and the effect these may have on assessed global temperatures The latter likely lead to a small underestimation of global warming trends in the last decade or so, and their effects may be comparable to uncertainties in or underestimations of Arctic temperatures. In this context, we present a multiple regression model of the main factors affecting global annual mean surface temperature (land and ocean combined) using the HadCRUT3, NCDC and GISS data sets for 1891-2009. The significant factors are net greenhouse gas forcing offset by anthropogenic aerosols, ENSO effects lagged by 3-5 months as measured by Nino 3.4 SSTs, solar and volcanic forcings and a small contribution from the Atlantic Multidecadal Oscillation. The regression equation verifies well when cross validated. This also allows the contributions of individual factors to be identified with more accuracy. We call this the simulation model. When restricted to 1891-1998, the simulation model reproduces the observed interannual variations of global temperature over 1999-2010 well. It therefore well reproduces the recent slowing of global warming whose magnitude, however, depend a little on assessments of recent Arctic temperature change which differ between HadCRUT3 and GISS especially. Slowing of the warming over 2001-2009 is likely partly to the 11 year solar cycle and recently published work elsewhere on a reduction of lower stratospheric water vapour. Nevertheless, we show that decadal temperature change from 1999-2008, as measured by HadCRUT3, is still consistent with future projections of global warming to 2100 under strong enhanced greenhouse forcing. The method we use includes a set of perturbed HadCM3 coupled climate model simulations. The statistical model has been adapted to forecast global surface temperature for the year ahead using data available in the previous November or December. A variation on this uses forecasts of Nino 3.4 SST from the Met Office’s Glosea3 or Glosea4 coupled seasonal forecast models. Using cross validation, the forecast models have been tested for their true forecast skill. Since 2008, initialised dynamical predictions from the DePreSys coupled decadal forecast model have been included and we briefly discuss these predictions. We assess the skill of the 11 real-time global surface temperature forecasts one year ahead issued in Press Releases over 2000-2010. Although the 2010 value is preliminary, we compare observations to date with our forecast of a record warm year. The two statistical models have evolved since this the first real time forecast in 2000, and were calibrated against earlier versions of Met Office global surface temperature data sets, so we verify against the contemporary data. Although there is a small warm bias when assessed against HadCRUT3 which may partly relate to underestimation of recent Arctic temperatures, the correlation coefficient between the 11 observed and forecast temperatures exceeds 0.70.

  11. 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.

  12. 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.

  13. 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.

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

    PubMed

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

    2001-11-01

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

  15. Linear temperature dependence of conductivity in the "insulating" regime of dilute two-dimensional holes in GaAs.

    SciTech Connect

    Simmons, Jerry Alvon; Noh, Hwayong; Lilly, Michael Patrick; Tsui, Daniel Chee; West, Ken W.; Pfeiffer, Loren N.

    2003-06-01

    The conductivity of extremely high mobility dilute two-dimensional holes in GaAs changes linearly with temperature in the insulating side of the metal-insulator transition. Hopping conduction, characterized by an exponentially decreasing conductivity with decreasing temperature, is not observed when the conductivity is smaller than e{sup 2}/h. We suggest that strong interactions in a regime close to the Wigner crystallization must be playing a role in the unusual transport.

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

    PubMed

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

    2015-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-08-01

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

  18. 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 a similar pattern of month-to-month oscillation and six months of enhanced and a statistically significant warming trend. The enhanced warming trend during the winter and pre-monsoon months (December-May) may accelerate glacial melt. The unequal distribution of the warming trend over the year is discussed in this study and is partially attributed to a number of controlling factors such as sunlight duration, CO2 trends over the region (2003-2008), water vapor and aerosol distribution.

  19. Impacts of land surface properties on temperature trends over the United States: Assessment using the US historical climate network and North American regional reanalysis datasets

    NASA Astrophysics Data System (ADS)

    Fall, Souleymane

    2009-12-01

    Temperature trends result from natural and anthropogenic factors. The latter was first seen as the result of radiative forcings, mainly the increasing concentrations of greenhouse gases. However, the increasing evidence that some non-radiative forcings such as land use/land cover (LULC) change may also be major factors contributing to climate change has prompted the National Research Council (NRC, 2005) to recommend the broadening of the climate change issue to include LULC processes as an important climate forcing. In addition, at the station level, increasing attention has been given to non-climatic biases that affect temperature records due to changes of the local environment at the vicinity of the station, changes in instrumentation and/or observations practices. This study (i) uses comparisons between in-situ observations and reanalysis datasets as an independent method to estimate temperature trends and variability and evaluate adjustments made to temperature records to correct non-climatic biases, (ii) uses the Observation Minus Reanalysis (OMR) method to investigate the impacts of sensitivity of surface temperature trends to LULC change over the conterminous United States and (iii) compares temperature and equivalent temperature (which is a variable that combines both temperature and moisture) and analyzes their respective correlation to vegetation properties. The comparison between the reanalysis and in-situ temperature observations shows that the reanalysis faithfully captures the intraseasonal and interannual variability of the station observations and also provides valuable information about the effects of individual station location (well or poorly sited) on temperature observations. Moreover, the comparison between surface observations and the North American Regional Reanalysis (NARR) using the Mean Square Difference (MSD) method is efficient in detecting LULC changes that took place at the vicinity of stations or changes related to observation practices, and in evaluating the impacts of adjustments performed on raw observations. OMR trends were found to be sensitive to land cover types and results indicate that land use conversion often results in more warming than cooling. Overall, our results confirm the robustness of the OMR method for capturing patterns of LULC changes at local and regional scales. The comparison between temperature and equivalent temperature demonstrates that atmospheric heat content may help to quantify the differences between surface and tropospheric trends, and hence the impact of land cover types on the surface temperature changes. Moreover, equivalent temperature is more correlated to biomass increase, vegetation transpiration and other surface moisture characteristics. Overall, this study suggests that in addition to considering the greenhouse gases-driven radiative forcings, multi-decadal and longer climate models simulations must further include LULC changes.

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

    E-print Network

    Hammett, Greg

    Experiment and a shaped tokamak J. A. Baumgaertel, G. W. Hammett, and D. R. Mikkelsen Citation: Phys. Plasmas Stellarator Experiment and a shaped tokamak J. A. Baumgaertel,1 G. W. Hammett,2 and D. R. Mikkelsen2 1 Los for the linear, collisionless ion temperature gradient (ITG) mode in the National Compact Stellarator Experiment

  1. 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.

  2. 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

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

  3. 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-range dependence. Four different data products, HADCRUT4, NOAA mlost, GISS and Berkely Earth, are analyzed in this project, with similar results in all cases.

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

    E-print Network

    Richerme, Philip J

    2006-01-01

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

  5. 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...

  6. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

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

    SciTech Connect

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

    2014-11-11

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

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

    NASA Technical Reports Server (NTRS)

    Susskind, Joel; Molnar, Gyula

    2009-01-01

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

  10. 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.

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

    NASA Astrophysics Data System (ADS)

    Andreev, P. A.

    2013-03-01

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

  12. Particulate matter modifies the magnitude and time course of the non-linear temperature-mortality association.

    PubMed

    Li, Li; Yang, Jun; Guo, Cui; Chen, Ping-Yan; Ou, Chun-Quan; Guo, Yuming

    2015-01-01

    It remains uncertain whether air pollution modifies the magnitude and time course of the temperature mortality association. We applied a distributed lag non-linear model (DLNM) combined with non-linear interaction terms to assess the modifying effects of particulate matter with an aerodynamic diameter of 10 mm or less (PM(10)) on the association between mean temperature and mortality in Guangzhou, China.We found that both cold and hot effects increased with the quartiles of PM(10). The elderly were more vulnerable to cold and hot effects. Men suffered more from cold-related mortality than women, with the gender difference enlarging with the quartiles of PM(10). We identified statistically significant interaction effects between PM(10) and mean temperature on mortality (except for respiratory mortality). Cold and hot effects basically appeared acutely on highly polluted days, while effects were delayed on lowly polluted days. The findings indicate the importance of reducing PM(10) emission on extremely temperature days. PMID:25468212

  13. Dynamical Adjustment of Surface Air Temperature Fields from Large Initial-Condition Ensemble Simulations: Ensemble Spread and Multi-Decadal Trend Attribution

    NASA Astrophysics Data System (ADS)

    Smoliak, B. V.; Deser, C.; Phillips, A.

    2014-12-01

    Boreal cold season surface air temperature (SAT) variability and trends attributable to fluctuations in large-scale patterns of sea-level pressure (SLP) anomalies are investigated in a large initial-condition (IC) ensemble of general circulation model climate change simulations using partial least squares (PLS) regression, a statistical method that specifies a predictand time series or field using multiple mutually orthogonal factors generated from a field of predictors. This specification represents a dynamical adjustment to the raw SAT field, which reduces ensemble spread by accounting for the influence of spontaneously-occurring atmospheric circulation changes unique to each ensemble member (EM). When applied independently to the simulated Northern Hemisphere (NH) SAT field from individual EMs, the methodology yields a dynamical adjustment that accounts for nearly 50% of the cold season SAT variance in each EM, validating a previous application of PLS regression to observations. Dynamical adjustment is also applied to SAT trends across the large IC ensemble, enabling the attribution of multi-decadal trends to external forcing and internal variability as well as dynamical and radiative/thermodynamic processes. When applied to the ensemble of SAT and SLP trends over a multi-decadal mid-21st Century reference interval, the methodology yields a dynamical adjustment that explains over 75% of the intra-ensemble variance of the NHSAT warming trend and accounts for about 5% of the ensemble-mean NHSAT warming trend. This methodological framework may be applied to other large IC ensembles, other climatological variables, and across a wider variety of time scales in order to investigate the role of internal variability in modulating the magnitude and patterns of historical and projected climate change.

  14. 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 d? / 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.

  15. 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.

  16. 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.

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

    NASA Astrophysics Data System (ADS)

    Zhu, Jianwei; Shi, Daning

    2011-11-01

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

  18. 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.

  19. 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.

  20. 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.

  1. The Fermion Boson Interaction Within the Linear Sigma Model at Finite Temperature

    E-print Network

    Caldas, H C G

    2002-01-01

    We study the interaction of massless fermions with massless bosons at finite temperature. Specifically, we calculate the self-energy of massless fermions due the interaction with massless bosons at high temperature, which is the region where thermal effects are maximal. The calculations are concentrated in the limit of vanishing fermion three momentum and after considering the effective boson dressed mass, we obtain the damping rate of the fermion. It is shown that in the limit $k_0 \\ll T$ the fermion acquire a thermal mass of order gT and the leading term of the fermion damping rate is of order $g^2T+g^3T$.

  2. 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 (? ~ 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 (? ? 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-Na relation similar to that previously found for more metal-poor stars albeit with a smaller amplitude. Furthermore, the C/O ratio evolves very little with time, although [C/Fe] and [O/Fe] change by ~0.15 dex. Conclusions: The dependence of [X/Fe] on stellar age and the [Ni/Fe]- [Na/Fe] variations complicate the use of the [X/Fe]-TC relation as a possible signature for the existence of terrestrial planets around stars. The age trends for the various abundance ratios provide new constraints on supernovae yields and Galactic chemical evolution, and the slow evolution of C/O for solar metallicity stars is of interest for discussions of the composition of exoplanets. Based on data products from observations made with ESO Telescopes at the La Silla Paranal Observatory under programs given in Table 1.Tables 2 and 3 are available in electronic form at http://www.aanda.org

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

    E-print Network

    Rypdal, Martin

    2013-01-01

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

  4. 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.

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

    E-print Network

    Russell, Kasey

    Linear photon upconversion of 400 meV in an AlGaInP/GaInP quantum well heterostructure to visible light at room temperature M. R. Olson,a K. J. Russell, and V. Narayanamurti Division of Engineering online 17 April 2006 We linearly up convert photons from 820 to 650 nm, an energy change of 400 me

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

    NASA Astrophysics Data System (ADS)

    Perrault-Joncas, Dominique; Maslowe, Sherwin A.

    2008-07-01

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

  7. High temperature spin dynamics in linear magnetic chains, molecular rings, and segments by nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Adelnia, Fatemeh; Mariani, Manuel; Ammannato, Luca; Caneschi, Andrea; Rovai, Donella; Winpenny, Richard; Timco, Grigore; Corti, Maurizio; Lascialfari, Alessandro; Borsa, Ferdinando

    2015-05-01

    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)3NITEt and the magnetically frustrated Gd(hfac)3NITEt. 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 Cr8 closed ring and in Cr7Cd and Cr8Zn 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.

  8. 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 ?/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).

  9. Historical Trends

    Cancer.gov

    Close Window State Cancer Profiles Quick Reference Guides ? Back to Historical Trends Reference Guide Historical Trends This graphic shows the Historical Trends Graph for female breast cancer mortality in the United States, 1975-2011. There are various

  10. 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 to extratropical basins, when the cool phase of the SST trend coincided with a warm phase of the Atlantic Multidecadal Oscillation (AMO). Dry (wet) anomalies during the 1950s (1980s) are shown linked to the warm (cool) phase of the North Pacific decadal mode, as well as a warm (cool) AMO. The analysis suggests comparable importance of the Pacific and Atlantic Oceans in drought forcing, and highlights the role of the extratropical basins.

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

    NASA Astrophysics Data System (ADS)

    van Belle, Gerard; Ciardi, David R.; von Braun, Kaspar; Pilyavsky, Genady

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

    van Belle, Gerard; Pilyavsky, Gennady; von Braun, Kaspar; Ciardi, David R.; PTI Collaboration

    2016-01-01

    We report new interferometric angular diameter observations of over 200 giant stars observed with the Palomar Testbed Interferometer (PTI). These angular diameters are combined with bolometric fluxes derived from detailed spectral energy distribution (SED) fits, to produce robust estimates of effective temperature (TEFF). These SED fits include reddening estimates and are based upon fits of empirical spectral templates to literature photometry, and narrow-band photometry obtained at the Lowell 31" telescope. The 58 nights of 31" observing have produced over 45,000 new photometric data points on these stars, allowing for flux and reddening determination with unprecident precision. Over the range from G5III to M8III, TEFF estimates are precise to 50K per spectral type. Radius estimates are limited by the improved Hipparcos estimates of van Leeuwen (2007) and are typically ~10% per star.

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

    SciTech Connect

    Singh, S. K.; Awasthi, L. M.; Singh, R.; Kaw, P. K.; Jha, R.; Mattoo, S. K.

    2011-10-15

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

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

    SciTech Connect

    Schnack, D. D.; Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 ; Cheng, J.; Parker, S. E.; Barnes, D. C.

    2013-06-15

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

  16. 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??i or ?i/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 ? =?r+i?. An explicit solution is derived for the growth rate and real frequency in this regime. These are found to depend on a single non-dimensional parameter. We also compute the eigenvalues and the eigenfunctions with the extended MHD code NIMROD, and a hybrid kinetic ?f code that assumes six-dimensional Vlasov ions and isothermal fluid electrons, as functions of k??i and ?i/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??i or ?i/LTi0 increases. There is good qualitative agreement between the models for the shape of the unstable global eigenfunction for LTi0/?i=30 and 20. The results quantify how far fluid calculations can be extended accurately into the kinetic regime. We conclude that for the linear ITG problem in slab geometry with unsheared magnetic field when k?/k??1, the extended MHD model may be a reliable physical model for this problem when ?i/LTi0<10-2 and k??i<0.2.

  17. 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 speci?c phenological responses. Spring Indices (SI) are a set of complex phenological models that have been successfully applied to evaluate variations and trends in the onset of spring across the Northern Hemisphere’s temperate regions. To date, SI models have been limited by only producing output in locations where both the plants’ chilling and warmth requirements are met. Here, we develop an extended form of the SI (abbreviated SI-x) that expands their application into the subtropics by ignoring chilling requirements while still retaining the utility and accuracy of the original SI (now abbreviated SI-o). The validity of the new indices is tested, and regional SI anomalies are explored across the data-rich continental United States. SI-x variations from 1900 to 2010 show an abrupt and sustained delay in spring onset of about 4–8 d (around 1958) in parts of the Southeast and southern Great Plains, and a comparable advance of 4–8 d (around 1984) in parts of the northern Great Plains and the West. Atmospheric circulation anomalies, linked to large-scale modes of variability, exert modest but signi?cant roles in the timing of spring onset across the United States on interannual and longer timescales. The SI-x are promising metrics for tracking spring onset variations and trends in mid-latitudes, relating them to relevant ecological, hydrological, and socioeconomic phenomena, and exploring connections between atmospheric drivers and seasonal timing.

  18. 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.

  19. Temperature evolution of the linear birefringence in striated single crystals of KTa1-xNbxO3 (KTN)

    NASA Astrophysics Data System (ADS)

    Jackson, Daniel; Pattnaik, Radha; Agranat, Aharon; Toulouse, Jean

    2012-02-01

    We report the temperature evolution of a special linear birefringence in 3 crystals of KTa1-xNbxO3 (KTN), with x=0.155, 0.27 and 0.36 respectively, upon approaching the cubic-tetragonal phase transition. This birefringence, which is in violation of crystalline symmetry conditions, is caused by growth striations in the crystal that give rise to local strain and result in an average uniaxial behavior due to the photoelastic effect. Simultaneously, the set of parallel striations acts as a volume phase grating which can produce diffracted beams. Upon approaching the phase transition, the measured birefringence displays a rapid temperature dependence which is due to the formation of polar nano-domains (PND). These are incipient tetragonal uniaxial domains preferentially oriented with their c-axis perpendicular to the plane of the striations. As the birefringence increases, the diffraction efficiency unexpectedly decreases, indicating that the phase grating amplitude is occluded by the PND formation. The striation pattern is well defined in the 15.5% crystal, more diffuse in the 36% crystal, and there are no obvious striations in the 27% crystal. Experimental results are presented and a simple phenomenological model for the birefringence behavior is proposed and discussed.

  20. 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.

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

    E-print Network

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

    2009-01-08

    temperature and precipitation in IPCC AR4 GCM output for Kansas, USA: evaluation and implications N. A. Brunsell,* A. R. Jones, T. L. Jackson and J. J. Feddema Department of Geography, University of Kansas, Lawrence KS 66044, USA ABSTRACT: Understanding... precipitation gradient found, primarily focusing on an area encompassing the state of Kansas. The Inter- governmental Panel on Climate Change (IPCC, 2007) projects that subtropical regions are likely to be most affected by GHG emissions, with significant...

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

    NASA Astrophysics Data System (ADS)

    Chen, Shangfeng; Chen, Wen; Wei, Ke

    2013-11-01

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

  3. Linear and nonlinear transmission of Fe{sup 2+}-doped ZnSe crystals at a wavelength of 2940 nm in the temperature range 20–220 °C

    SciTech Connect

    Il'ichev, N N; Pashinin, P P; Gulyamova, E S; Bufetova, G A; Shapkin, P V; Nasibov, A S

    2014-03-28

    The linear and nonlinear transmission of Fe{sup 2+}:ZnSe crystals is measured at a wavelength of 2940 nm in the temperature range 20 – 220 °C. It is found that, with increasing temperature from 20 °C to 150 – 220 °C, the transmission of Fe{sup 2+}:ZnSe crystals decreases in the case of incident radiation with an intensity of ?5.5 MW cm{sup -2} and increases in the case of radiation with an intensity of 28 kW cm{sup -2}. At a temperature of 220 °C, the linear transmission almost coincides with the nonlinear transmission. The transmission spectra of Fe{sup 2+}:ZnSe crystals at temperatures of 22 and 220 °C in the wavelength range 500 – 7000 nm are presented. (active media)

  4. 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.

  5. Thermal fractionalization of quantum spins in a Kitaev model: Temperature-linear specific heat and coherent transport of Majorana fermions

    NASA Astrophysics Data System (ADS)

    Nasu, Joji; Udagawa, Masafumi; Motome, Yukitoshi

    2015-09-01

    Finite-temperature (T ) properties of a Kitaev model defined on a honeycomb lattice are investigated by a quantum Monte Carlo simulation, from the viewpoint of fractionalization of quantum S =1 /2 spins into two types of Majorana fermions, itinerant and localized. In this system, the entropy is released successively at two well-separated T scales, as a clear indication of the thermal fractionalization. We show that the high-T crossover, which is driven by itinerant Majorana fermions, is closely related with the development of nearest-neighbor spin correlations. On the other hand, the low-T crossover originates in thermal fluctuations of fluxes composed of localized Majorana fermions, by which the spectrum of itinerant Majorana fermions is significantly disturbed. As a consequence, in the intermediate-T range between the two crossovers, the system exhibits T -linear behavior in the specific heat and coherent transport of Majorana fermions, which are unexpected for the Dirac semimetallic spectrum in the low-T limit. We also show that the flux fluctuations tend to open an energy gap in the Majorana spectrum near the gapless-gapped phase boundary. Our results indicate that the fractionalization is experimentally observable in the specific heat, spin correlations, and transport properties.

  6. 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 ?K which could potentially be measured by Planck HFI and Pixie experiments and can be used as a source of cross channel calibration by CMB experiments. This y-type distortion is present in every pixel and is not the result of averaging the whole sky. This distortion, calculated exactly from the known linear dipole, can be subtracted from the final y-type maps, if desired.

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  8. 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 another GPS station at the top of predicted centre of magma chamber correlates well with OLAF site at 500 m distance from MASK. Average subsidence rates derived from GPS measurements show comparable rate derived from InSAR data. Velocities derived from InSAR show that the yearly maximum subsidence rates in the Askja caldera decrease linearly. The optimized pressure decrease in the magma chamber from the model follows an exponential decay, with P (MPa) = 2.0177 EXP(-0.0176x), where x is the numbers of years (1,2,3 .. 10). However total ramp pressure drop during this period (10 years) is 4 MPa and additional 4.68 MPa pressure drop may be caused of rheological relaxation.

  9. Methodology for Characterizing Trends | Cancer Trends Progress Report

    Cancer.gov

    In order to obtain a consistent characterization of population trends in factors related to the prevention, early detection, or treatment of cancer, the joinpoint statistical methodology was used in this report. This methodology characterizes a trend using joined linear segments on a logarithmic scale; the point where two segments meet is called a "joinpoint." The methodology is used to characterize trends in cancer incidence and mortality rates (e.g., in the SEER Cancer Statistics Review).

  10. 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.

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

    PubMed

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

    2015-03-10

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

  12. High-precision abundances of elements in solar twin stars: Trends with stellar age and elemental condensation temperature

    E-print Network

    Nissen, Poul E

    2015-01-01

    HARPS spectra with S/N > 600 for 21 solar twin stars are used to determine very precise (sigma ~ 0.01 dex) differential abundances of C, O, Na, Mg, Al, Si, S, Ca, Ti, Cr, Fe, Ni, Zn, and Y in order to see how well [X/Fe] is correlated with elemental condensation temperature, Tc. In addition, precise (sigma Teff diagram. It is confirmed that the ratio between refractory and volatile elements is lower in the Sun than in most of the solar twins, but for many stars, the relation between [X/Fe] and Tc is not well defined. For several elements there is, instead, an astonishingly tight correlation between [X/Fe] and stellar age with amplitudes up to 0.2 dex over an age interval of 8 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 so that [Y/Mg] can be used as a sensitive chronometer for Galactic evolution. ...

  13. 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 (?11B) 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

  14. Linear Electro-optic Conversion of Sampled Voltage Signals Using a Low-Temperature-Grown GaAs MSM and a

    E-print Network

    Miller, David A. B.

    Linear Electro-optic Conversion of Sampled Voltage Signals Using a Low-Temperature-Grown GaAs MSM-semiconductor-metal (MSM) photoconductive switch The photoconductive switch used in our experiments is fabricated on low the normal ~600 o C. The wafer is subsequently annealed for 1 minute at 700 o C. The MSM structure consists

  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. Recent climate trends and multisecular climate variability: temperature and precipitation during the cold season (October-March) in the Ebro Basin (NE of Spain) betrween 1500 and 2008

    NASA Astrophysics Data System (ADS)

    Saz-Sanchez, M.-A.; Cuadrat-Prats, J.-M.

    2009-09-01

    One of the goals of Paleoclimatology is to assess the importance and the exceptional nature of recent climate trends related to the anthropogenic climate change. Instrumental data enable the analysis of last century's climate, but do not give any information on previous periods' precipitation and temperature, during which there was no anthropic intervention on the climate system. Dendroclimatology is one of the paleoclimatic reconstruction sources giving best results when it comes to reconstructing the climate of the time before instruments could be used. This work presents the reconstructed series of precipitation and temperature of the cold season (October-March) In the central sector of the Ebro Valley (NE of Spain). The chronologies used for the reconstruction come on the one hand from the International Tree-Ring Data Bank (ITRDB) and on the other hand from the dendrochronological information bank created in the northern half of the Iberian Peninsula within the framework of the Spanish Interministerial Commission for Science and Technology (CICYT) CLI96-1862 project. The climate data used for chronology calibration and the reconstruction of the temperature and precipitation values are those of the instrumental observatory number 9910 (Pallaruelo) belonging to the Spanish State Meteorological Agency (Agencia Estatal de Meteorología or AEMET), located in the central sector of the Ebro Valley. The reconstruction obtained covers the 1500-1990 period. In order to extend the series up to 2008, instrumental information has been used. Thanks to data from a set of AEMET instrumental observatories close to the one used for chronology calibration, a regional series of temperatures as well as a precipitation one were generated. The series reconstructed through dendroclimatic methods and the regional series do not show statistically significant differences in their mean and variance values. R values between both series exceed 0.85. Taking these statistical characteristics into account, with both series "hybrid series” of temperature and precipitation were created, in which the data reconstructed from 1955 on were replaced by those of the regional instrumental series. The resulting series were tested by means of the Standard Normal Homogeneity Test (SNHT) with the aim of assessing their homogeneity; the presence of inhomogeneities around the joining point between both series being undetected. The results stress the exceptional nature of the climate in the central sector of the Ebro Valley during the second half of the 20th century. The 1958-2007 period appears as the warmest since the 16th century, with an average temperature exceeding in 0.42 °C that of the reference 1850-1950 period. The two warmest decades take place from 1980 on. As for precipitations, they show a negative trend since the first third of the 20th century. The 1957-2006 period is the 50-year interval with the lowest average total precipitation, lower in 24.2 % to the reference period precipitation.

  19. Techniques for analyses of trends in GRUAN data

    NASA Astrophysics Data System (ADS)

    Bodeker, G. E.; Kremser, S.

    2014-12-01

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

  20. Techniques for analyses of trends in GRUAN data

    NASA Astrophysics Data System (ADS)

    Bodeker, G. E.; Kremser, S.

    2015-04-01

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

  1. Reconstructing Changes in Deep Ocean Temperature and Global Carbon Cycle during the Early Eocene Warming Trend: High-Resolution Benthic Stable Isotope Records from the SE Atlantic.

    NASA Astrophysics Data System (ADS)

    Lauretano, V.; Zachos, J. C.; Lourens, L. J.

    2014-12-01

    From the late Paleocene to the early Eocene, Earth's surface temperatures generally rose, resulting in an increase of at least 5°C in the deep ocean and culminating in the Early Eocene Climatic Optimum (EECO). This long-term warming was punctuated by a series of short-lived global warming events known as "hyperthermals", of which the Paleocene-Eocene Thermal Maximum (PETM) represents the most extreme example. At least two other short-term episodes have been identified as hyperthermals: the ETM2 (or Elmo event) at about 53.7 Myr and the ETM3 (or X-event) at about 52.5 Myr. These transient events are marked by prominent carbon isotope excursions (CIEs), recorded in marine and continental sedimentary sequences and driven by fast and massive injections of 13C-depleted carbon into the ocean-atmosphere system. Recently, evidence has indicated the presence of a regular series of hyperthermal events following the peak in temperatures of the EECO. However, continuous records are needed to investigate short- and long- term changes in the climate system throughout the Early Eocene warming trend. Here, we present new high-resolution benthic stable isotope records of the Early Eocene from ODP Site 1263, (Walvis Ridge, SE Atlantic). The carbon and oxygen records document changes in deep-sea temperature and global carbon cycle encompassing the Early Eocene hyperthermal events and the EECO interval. The transition phase to the post-EECO events is distinct by the decoupling of carbon and oxygen isotopes on the long-term scale. Spectral and wavelet analyses suggest the influence of orbital forcing, specifically long and short eccentricity cycles.

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

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

  3. Enterprise Trends

    ERIC Educational Resources Information Center

    Technology & Learning, 2007

    2007-01-01

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

  4. Observed Trends in Subtropical Stratocumulus and Associated Meteorology

    NASA Astrophysics Data System (ADS)

    Chellappan, S.; Norris, J. R.; Myers, T. A.

    2014-12-01

    The importance of low-level cloud feedbacks to climate sensitivity motivates an investigation of how low-level cloud amount, liquid water path, and related meteorological conditions have changed in recent decades in subtropical stratocumulus regions. Using a satellite cloud dataset corrected for inhomogeneities, we find that during 1984-2009 low-level cloud amount significantly increased over the northeast and southeast Pacific, significantly decreased over the northeast Atlantic, and weakly increased over the southeast Atlantic and southeast Indian oceans. During 1988-2012, liquid water path decreased over the northeast Pacific, significantly increased over the southeast Pacific and northeast and southeast Atlantic, and weakly increased over the southeast Indian oceans. Examination of meteorological parameters from four re-analyses indicates that positive trends in low-level cloud amount are associated with decreasing trends in sea surface temperature and increasing trends in inversion strength, subsidence and cold-air advection, and vice-versa. Relationships between liquid water path and meteorological conditions are weaker, but increasing trends in liquid water path are associated with increasing trends in sea surface temperature and decreasing trends in inversion strength, subsidence, and cold-air advection, and vice-versa. A multi-linear regression model based on these four meteorological variables well captures the sign and to certain extent magnitude of observed cloud amount trends in almost all stratocumulus regions, but a similarly constructed model largely fails to reproduce the observed liquid water path trends. Differing signs of cloud trends and differing contributions from meteorological parameters between regions suggest that observed changes in subtropical stratocumulus since the 1980s are primarily due to natural variability rather than a systematic response to climate change.

  5. Changes in Stratospheric Temperatures and Their Implications for Changes in the BrewerDobson Circulation, 19792005

    E-print Network

    Sherwood, Steven

    Changes in Stratospheric Temperatures and Their Implications for Changes in the Brewer Sounding Unit (MSU), Stratospheric Sounding Unit (SSU), and radiosondes. Linear trends in an empirically throughout the depth of the stratosphere. Trends in the same index suggest a significant strengthening

  6. 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…

  7. Nationwide Trends

    MedlinePLUS

    ... Abused Drugs Charts Emerging Trends Alcohol Club Drugs Cocaine Hallucinogens Heroin Inhalants Marijuana MDMA (Ecstasy/Molly) Methamphetamine ... includes ecstasy and LSD) in the past month. Cocaine use has gone down in the last few ...

  8. Historical Trends

    Cancer.gov

    Close Window State Cancer Profiles Quick Reference Guides ? Quick Reference Guides Index Historical Trends Send to Printer Text description of this image. Site Home Policies Accessibility Viewing Files FOIA Contact Us U.S. Department of Health and Human

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

    NASA Astrophysics Data System (ADS)

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

    2011-11-01

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

  10. 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.

  11. 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;…

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

    NASA Astrophysics Data System (ADS)

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

    2005-08-01

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

  13. 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 study will bring about more insights for understanding of regional temperature and precipitation behavior over the last several decades in North Carolina.

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

    E-print Network

    Banerjee, Debjyoti

    excellent high frequency response [16] due to its low thermal inertia. Theycan be fabricated is obtained at each steady state condition to generate the boiling curve. The fraction of false, the minimal thermal inertia and small feature size leads to a reduced distortion of the temperature

  15. Density-functional theory of freezing of quantum liquids at zero temperature using exact liquid-state linear response

    E-print Network

    Likos, Christos N.

    Density-functional theory of freezing of quantum liquids at zero temperature using exact liquid, Strada Costiera 11, I-34014 Grignano, Trieste, Italy Received 27 August 1996 We apply density assumed. We find that, as a result of this exact behavior, different approximations in the density

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

    PubMed Central

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

    2011-01-01

    Understanding how vegetation growth responds to climate change is a critical requirement for projecting future ecosystem dynamics. Parts of North America (NA) have experienced a spring cooling trend over the last three decades, but little is known about the response of vegetation growth to this change. Using observed climate data and satellite-derived Normalized Difference Vegetation Index (NDVI) data from 1982 to 2006, we investigated changes in spring (April–May) temperature trends and their impact on vegetation growth in NA. A piecewise linear regression approach shows that the trend in spring temperature is not continuous through the 25-year period. In the northwestern region of NA, spring temperature increased until the late 1980s or early 1990s, and stalled or decreased afterwards. In response, a spring vegetation greening trend, which was evident in this region during the 1980s, stalled or reversed recently. Conversely, an opposite phenomenon occurred in the northeastern region of NA due to different spring temperature trends. Additionally, the trends of summer vegetation growth vary between the periods before and after the turning point (TP) of spring temperature trends. This change cannot be fully explained by summer drought stress change alone and is partly explained by changes in the trends of spring temperature as well as those of summer temperature. As reported in previous studies, summer vegetation browning trends have occurred in the northwestern region of NA since the early 1990s, which is consistent with the spring and summer cooling trends in this region during this period. PMID:21220297

  17. Updated PMC trends derived from SBUV data

    NASA Astrophysics Data System (ADS)

    DeLand, Matthew T.; Thomas, Gary E.

    2015-03-01

    Previous analysis of polar mesospheric clouds (PMCs) observed by Solar Backscatter Ultraviolet (SBUV) instruments found that long-term variations in PMC brightness and occurrence frequency were anticorrelated with solar activity and that an increasing secular trend was present at most latitudes. In this paper, long-term PMC variations are presented in terms of ice water content (IWC), a physically based variable which is easier to interpret than previously reported UV albedo values. This model-based conversion from albedo to IWC removes most scattering angle effects. The derived long-term PMC variations in the SBUV data set are qualitatively the same using either an empirically derived adjustment for local time effects or no adjustment (i.e., assuming cancelation of interannual variations in tidally induced amplitude and/or phase). When we use stratospheric ozone variations as a proxy for mesospheric temperature changes, as suggested by recent model studies, we can explain more of the long-term IWC variability than if we use a linear trend. These results show that PMC ice water content in bright clouds increased rapidly from 1979 through the late 1990s and has been approximately constant from the late 1990s through 2013. The numerical value and sign of this trend during the last 15 years depend on the choice of end points and latitude band. Simultaneously, the solar response of IWC observed by SBUV has weakened during the most recent cycle in the Northern Hemisphere, but increased in the Southern Hemisphere.

  18. 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...

  19. 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 dendritically stabilized NPs is believed to have a potential for future biomedical and other applications, in which stability, resistance to (or reversible) aggregation, ultrasmall size (for crossing biological barriers or inclusion in responsive artificial membranes), and/or high corona density of (bio)active ligands are key. PMID:23214719

  20. 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.

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

    PubMed

    Chen, Xiaoqiu; Tian, Youhua; Xu, Lin

    2015-10-01

    Using leaf unfolding and leaf coloration data of a widely distributed herbaceous species, Taraxacum mongolicum, we detected linear trend and temperature response of the growing season at 52 stations from 1990 to 2009. Across the research region, the mean growing season beginning date marginal significantly advanced at a rate of -2.1 days per decade, while the mean growing season end date was significantly delayed at a rate of 3.1 days per decade. The mean growing season length was significantly prolonged at a rate of 5.1 days per decade. Over the 52 stations, linear trends of the beginning date correlate negatively with linear trends of spring temperature, whereas linear trends of the end date and length correlate positively with linear trends of autumn temperature and annual mean temperature. Moreover, the growing season linear trends are also closely related to the growing season responses to temperature and geographic coordinates plus elevation. Regarding growing season responses to temperature, a 1 °C increase in regional mean spring temperature results in an advancement of 2.1 days in regional mean growing season beginning date, and a 1 °C increase in regional mean autumn temperature causes a delay of 2.3 days in regional mean growing season end date. A 1 °C increase in regional annual mean temperature induces an extension of 8.7 days in regional mean growing season length. Over the 52 stations, response of the beginning date to spring temperature depends mainly on local annual mean temperature and geographic coordinates plus elevation. Namely, a 1 °C increase in spring temperature induces a larger advancement of the beginning date at warmer locations with lower latitudes and further west longitudes than at colder locations with higher latitudes and further east longitudes, while a 1 °C increase in spring temperature causes a larger advancement of the beginning date at higher than at lower elevations. PMID:25627826

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

    NASA Astrophysics Data System (ADS)

    Chen, Xiaoqiu; Tian, Youhua; Xu, Lin

    2015-10-01

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

  3. SBUV Version 4 PMC Data and Trend Analysis: Did the Trend Change in the mid-1990's?

    NASA Astrophysics Data System (ADS)

    DeLand, M. T.; Thomas, G. E.

    2014-12-01

    We have developed an updated Version 4 (V4) polar mesospheric cloud (PMC) data set from 35 years of SBUV measurements. The detection threshold has been revised to better represent the expected variation of PMC brightness with scattering angle. We now recommend the use of 273 nm directional albedo values to reduce uncertainties associated with instrument noise. We present our analysis of the V4 PMC data set in terms of ice water content (IWC), using a parameterization of regression results from a microphysical model to determine IWC from observed albedo. While we derive a local time adjustment as a function of IWC in order to use all SBUV measurements, we also find that our long-term trend analysis is insensitive to the nature of this function. In contrast to our earlier published work assuming a linear long-term trend of the SBUV time series, our new multiple linear regression results indicate that the anti-correlated response to solar activity and the increasing trend were both stronger in the first part of our data record (through ~1996) compared to the latter part. The use of a two-part linear trend for this analysis provides a long-term forcing similar to observed variations in upper stratospheric ozone and lower stratospheric temperature, as suggested earlier by Lübken et al [2011]. The fraction of total variance in the IWC time series explained by the multiple regression model is significantly smaller for all Southern Hemisphere latitudes compared to the corresponding Northern Hemisphere latitude. This suggests that interannual variability (not captured by our simple model) plays a larger role in the Southern Hemisphere. Possible explanations for the mid-1990's 'break' in the long-term record are offered. Lübken, F.-J., and U. Berger (2011), Latitudinal and interhemispheric variation of stratospheric effects on mesospheric ice layer trends, J. Geophys. Res., 116, D00P03, doi:10.1029/2010JD015258.

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

    PubMed Central

    2014-01-01

    Background Malaria transmission is strongly determined by the environmental temperature and the environment is rarely constant. Therefore, mosquitoes and parasites are not only exposed to the mean temperature, but also to daily temperature variation. Recently, both theoretical and laboratory work has shown, in addition to mean temperatures, daily fluctuations in temperature can affect essential mosquito and parasite traits that determine malaria transmission intensity. However, so far there is no epidemiological evidence at the population level to this problem. Methods Thirty counties in southwest China were selected, and corresponding weekly malaria cases and weekly meteorological variables were collected from 2004 to 2009. Particularly, maximum, mean and minimum temperatures were collected. The daily temperature fluctuation was measured by the diurnal temperature range (DTR), the difference between the maximum and minimum temperature. The distributed lag non-linear model (MDLNM) was used to study the correlation between weekly malaria incidences and weekly mean temperatures, and the correlation pattern was allowed to vary over different levels of daily temperature fluctuations. Results The overall non-linear patterns for mean temperatures are distinct across different levels of DTR. When under cooler temperature conditions, the larger mean temperature effect on malaria incidences is found in the groups of higher DTR, suggesting that large daily temperature fluctuations act to speed up the malaria incidence in cooler environmental conditions. In contrast, high daily fluctuations under warmer conditions will lead to slow down the mean temperature effect. Furthermore, in the group of highest DTR, 24-25°C or 21-23°C are detected as the optimal temperature for the malaria transmission. Conclusion The environment is rarely constant, and the result highlights the need to consider temperature fluctuations as well as mean temperatures, when trying to understand or predict malaria transmission. This work may be the first epidemiological study confirming that the effect of the mean temperature depends on temperature fluctuations, resulting in relevant evidence at the population level. PMID:24886630

  5. New Trends in Educational Lighting Systems.

    ERIC Educational Resources Information Center

    Murphy, Peter

    2001-01-01

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

  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. Linear temperature behavior of thermopower and strong electron-electron scattering in thick F-doped SnO{sub 2} films

    SciTech Connect

    Lang, Wen-Jing; Li, Zhi-Qing

    2014-07-28

    Both the semi-classical and quantum transport properties of F-doped SnO{sub 2} thick films (?1??m) were investigated experimentally. We found that the resistivity caused by the thermal phonons obeys Bloch-Grüneisen law from ?90 to 300?K, while only the diffusive thermopower, which varies linearly with temperature from 300 down to 10?K, can be observed. The phonon-drag thermopower is completely suppressed due to the long electron-phonon relaxation time in the compound. These observations, together with the fact that the carrier concentration has negligible temperature dependence, indicate that the conduction electrons in F-doped SnO{sub 2} films possess free-electron-like characteristics. At low temperatures, the electron-electron scattering dominates over the electron-phonon scattering and governs the inelastic scattering process. The theoretical predications of scattering rates of large- and small-energy-transfer electron-electron scattering processes, which are negligibly weak in three-dimensional disordered conventional conductors, are quantitatively tested in this lower carrier concentration and free-electron-like highly degenerate semiconductor.

  8. Trends in normalized US hurricane damages

    NASA Astrophysics Data System (ADS)

    Grinsted, Aslak; Ditlevsen, Peter; Madsen, Bo

    2015-04-01

    The lack of linear trend in hurricane damages after normalization have often been used to argue that observed loss trends can be explained entirely by socioeconomic factors. However, the loss data have an extremely skewed distribution, and least squares fitting is simply an inappropriate tool. Here we analyze normalized hurricane damage estimates and find a strong climatic trend in the data. The sensitivity implies that expected annual damages double for a one degree warming in the region.

  9. The application of two-step linear temperature program to thermal analysis for monitoring the lipid induction of Nostoc sp. KNUA003 in large scale cultivation.

    PubMed

    Kang, Bongmun; Yoon, Ho-Sung

    2015-02-01

    Recently, microalgae was considered as a renewable energy for fuel production because its production is nonseasonal and may take place on nonarable land. Despite all of these advantages, microalgal oil production is significantly affected by environmental factors. Furthermore, the large variability remains an important problem in measurement of algae productivity and compositional analysis, especially, the total lipid content. Thus, there is considerable interest in accurate determination of total lipid content during the biotechnological process. For these reason, various high-throughput technologies were suggested for accurate measurement of total lipids contained in the microorganisms, especially oleaginous microalgae. In addition, more advanced technologies were employed to quantify the total lipids of the microalgae without a pretreatment. However, these methods are difficult to measure total lipid content in wet form microalgae obtained from large-scale production. In present study, the thermal analysis performed with two-step linear temeperature program was applied to measure heat evolved in temperature range from 310 to 351 °C of Nostoc sp. KNUA003 obtained from large-scale cultivation. And then, we examined the relationship between the heat evolved in 310-351 °C (HE) and total lipid content of the wet Nostoc cell cultivated in raceway. As a result, the linear relationship was determined between HE value and total lipid content of Nostoc sp. KNUA003. Particularly, there was a linear relationship of 98% between the HE value and the total lipid content of the tested microorganism. Based on this relationship, the total lipid content converted from the heat evolved of wet Nostoc sp. KNUA003 could be used for monitoring its lipid induction in large-scale cultivation. PMID:25640725

  10. On the Applicability of the Linear Hoffman-Weeks Extrapolation to Determine the Equilibrium Melting Temperature of Semi-rigid Polymers.

    NASA Astrophysics Data System (ADS)

    Srinivas, S.; Marand, H.

    1997-03-01

    The estimation of the equilibrium melting temperature of polymers using the traditional Gibbs-Thomson and Hoffman-Weeks methods are critically reviewed. The conventional form of the Hoffman-Weeks equation has been extended to situations where polymer lamellae do not exhibit isothermal lamellar thickening (gamma = 1). Data from the literature for polymers displaying low degrees of crystallinity (i-PS, PPS and PEEK) have been reanalyzed using the exact form of the Hoffman-Weeks equation, leading to values considerably higher than previously reported in the literature. Our results call into question the applicability of the conventional form of the Hoffman-Weeks equation (linear extrapolation method) for all semi-rigid chain polymers, i.e polymers displaying low degrees of crystallinity.

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

    PubMed

    Mutelet, F; Rogalski, M

    2003-02-21

    An isothermal chromatographic method allowing determination of sigmabetaH2 and sigmaalphaH2 descriptors of the linear solvation energy relationship (LSER) was tested and results obtained are presented. This method is based on the use of four stationary phases of various polarity. On the other hand, it was demonstrated that the temperature gradient chromatography may be successfully used to determine LSER descriptors. Results of piH2, sigmabetaH2 and log L16 determination are reported. This approach opens new possibilities of precise and rapid determination of LSER descriptors of high boiling compounds using a small number of phases. It was demonstrated that the log L16 descriptor may be used to estimate vapor pressures of high boiling organic compounds with a better accuracy than those usually obtained with chromatographic methods. PMID:12647826

  12. Room-temperature single-photon sources with definite circular and linear polarizations based on single-emitter fluorescence in liquid crystal hosts

    NASA Astrophysics Data System (ADS)

    Winkler, Justin M.; Lukishova, Svetlana G.; Bissell, Luke J.

    2013-02-01

    Definite circular and linear polarizations of room-temperature single-photon sources, which can serve as polarization bases for quantum key distribution, are produced by doping planar-aligned liquid crystal hosts with single fluorescence emitters. Chiral 1-D photonic bandgap microcavities for a single handedness of circularly polarized light were prepared from both monomeric and oligomeric cholesteric liquid crystals. Fluorescent emitters, such as nanocrystal quantum dots, nitrogen vacancy color centers in nanodiamonds, and rare-earth ions in nanocrystals, were doped into these microcavity structures and used to produce circularly polarized fluorescence of definite handedness. Additionally, we observed circularly polarized resonances in the spectrum of nanocrystal quantum dot fluorescence at the edge of the cholesteric microcavity's photonic stopband. For this polarization we obtained a ~4.9 enhancement of intensity compared to the polarization of the opposite handedness that propagates without photonic bandgap microcavity effects. Such a resonance is indicative of coupling of quantum dot fluorescence to the cholesteric microcavity mode. We have also used planar-aligned nematic liquid crystal hosts to align DiI dye molecules doped into the host, thereby providing a single-photon source of linear polarization of definite direction. Antibunching is demonstrated for fluorescence of nanocrystal quantum dots, nitrogen vacancy color centers, and dye molecules in these liquid crystal structures.

  13. Fertilizer trends

    SciTech Connect

    Donaldson, R.

    1992-12-31

    This fourteenth edition of Fertilizer Trends presents historical fertilizer market data to aid industry, government, and financial market analysis and planners in their study of fertilizer and agricultural market cycles, market planning, and investment decisions. A 27-year summary of the US fertilizer market is presented in graphic and tabular form. Production, use, and trade data are included for each plant nutrient and sulfur. Canadian statistics have been included because of the important role of the Canadian fertilizer industry in the US fertilizer market. World production and consumption of nitrogen, phosphate, and potash are included because of the strong influence of world markets on the domestic market. Planted acreage and plant nutrient application rates for the major crops have been included to illustrate their effect on fertilizer use. Retail prices of the leading US fertilizer materials also are given.

  14. Fertilizer trends

    SciTech Connect

    Donaldson, R.

    1992-01-01

    This fourteenth edition of Fertilizer Trends presents historical fertilizer market data to aid industry, government, and financial market analysis and planners in their study of fertilizer and agricultural market cycles, market planning, and investment decisions. A 27-year summary of the US fertilizer market is presented in graphic and tabular form. Production, use, and trade data are included for each plant nutrient and sulfur. Canadian statistics have been included because of the important role of the Canadian fertilizer industry in the US fertilizer market. World production and consumption of nitrogen, phosphate, and potash are included because of the strong influence of world markets on the domestic market. Planted acreage and plant nutrient application rates for the major crops have been included to illustrate their effect on fertilizer use. Retail prices of the leading US fertilizer materials also are given.

  15. Effects of Polynomial Trends on Detrending Moving Average Analysis

    NASA Astrophysics Data System (ADS)

    Shao, Ying-Hui; Gu, Gao-Feng; Jiang, Zhi-Qiang; Zhou, Wei-Xing

    2015-07-01

    The detrending moving average (DMA) algorithm is one of the best performing methods to quantify the long-term correlations in nonstationary time series. As many long-term correlated time series in real systems contain various trends, we investigate the effects of polynomial trends on the scaling behaviors and the performances of three widely used DMA methods including backward algorithm (BDMA), centered algorithm (CDMA) and forward algorithm (FDMA). We derive a general framework for polynomial trends and obtain analytical results for constant shifts and linear trends. We find that the behavior of the CDMA method is not influenced by constant shifts. In contrast, linear trends cause a crossover in the CDMA fluctuation functions. We also find that constant shifts and linear trends cause crossovers in the fluctuation functions obtained from the BDMA and FDMA methods. When a crossover exists, the scaling behavior at small scales comes from the intrinsic time series while that at large scales is dominated by the constant shifts or linear trends. We also derive analytically the expressions of crossover scales and show that the crossover scale depends on the strength of the polynomial trends, the Hurst index, and in some cases (linear trends for BDMA and FDMA) the length of the time series. In all cases, the BDMA and the FDMA behave almost the same under the influence of constant shifts or linear trends. Extensive numerical experiments confirm excellently the analytical derivations. We conclude that the CDMA method outperforms the BDMA and FDMA methods in the presence of polynomial trends.

  16. The trendy trends: a fashion or a science story?

    NASA Astrophysics Data System (ADS)

    Papalexiou, S. M.; Zarkadoulas, N.

    2009-04-01

    The Nobelist physicist Niels Bohr once said that prediction is very difficult, especially if it is about the future. Nowadays, the scene has changed. It seems that since the scientific community accepted, in its majority, that the earth's climate is rapidly changing, an opinion that also echoes in public, scientists all over the world have identified significant trends in many climate related processes e.g. global temperature, rainfall, river discharges, ice melting etc. Furthermore, if we adopt the suggested trends in those natural processes and their future projections we should expect a horrifying future. But is that so? How consistent and scientifically sound are these trend based scenarios? A trend in its most common form can be expressed as a linear regression line fitted to an observed sample of the natural process under investigation. In addition, the decision of whether or not a trend is significant is based on inferences regarding the regression line coefficients. However, classical statistics inferences of the regression line coefficients assume normal and independent data, assumptions that are generally not valid in natural processes. Particularly, while the assumption of normality may hold in some cases, it is well documented that natural processes exhibit a great variety of autocorrelation structures, exponential or power type, and thus the assumption of independently distributed data is violated. In this study, we investigate based on Monte Carlo simulations the effect of different autocorrelation structures in the inference of the trend line significance. We demonstrate that trends considered as significant in a classical statistics framework are actually insignificant if autocorrelation structures are incorporated.

  17. 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, verification and reconstruction periods qualified it as a reasonable transfer function for our forest-limit (i.e., timberline) dataset. ANN appears a potential tool for other environments and/or proxies having more complex and noisier climatic relationships.

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

    PubMed

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

    2014-05-01

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

  19. The Relationship Between Air Temperature and Stream Temperature

    NASA Astrophysics Data System (ADS)

    Morrill, J. C.; Bales, R. C.; Conklin, M. H.

    2001-05-01

    This study examined the relationship, both linear and non-linear, between air temperature and stream temperature in order to determine if air temperature can be used as an accurate predictor of stream temperature, if general relationships could be developed that apply to a large number of streams, and how changes in stream temperature associated with climate variability or climate warming might affect the dissolved oxygen level, and thus the quality of life, in some of these streams. Understanding the relationship between air temperature and water temperature is important if we want to predict how stream temperatures are likely to respond to the increase in surface air temperature that is occurring. Data from over 50 streams in 13 countries, mostly gathered by K-12 students in the GLOBE program (Global Learning and Observations to Benefit the Environment), are examined. Only a few streams display a linear 1:1 air/water temperature trend. The majority of streams instead show an increase in water temperature of about 0.6 to 0.8 degrees for every 1-degree increase in air temperature. At some of these sites, where dissolved oxygen content is already low, an increase in summer stream temperatures of 2-3 degrees could cause the dissolved oxygen levels to fall into a critically low range. At some locations, such as near the source of a stream, water temperature does not change much despite wide ranges in air temperatures. The temperatures at these sites are likely to be least affected by surface warming. More data are needed in warmer climates, where the water temperature already gets above 25oC, in order to better examine the air/water temperature relationship under warmer conditions. Global average surface air temperature is expected to increase by 3-5oC by the middle of this century. Surface water temperature in streams, lakes and wetlands will likely increase as air temperature increases, although the change in water temperature may not be as large as the change in air temperature, and these changes in water temperatures could affect the health of many aquatic species.

  20. Report of the International Ozone Trends Panel 1988, volume 2

    NASA Technical Reports Server (NTRS)

    1989-01-01

    Chapters on the following topics are presented: trends in stratospheric temperature; theory and observations- model simulations of the period 1955-1985; trends in source gases; trends in stratospheric minor constituents; trends in aerosol abundances and distribution; and observations and theories related to antarctic ozone.

  1. Assessing surface air temperature variability using quantile regression

    NASA Astrophysics Data System (ADS)

    Timofeev, A. A.; Sterin, A. M.

    2014-12-01

    Many researches in climate change currently involve linear trends, based on measured variables. And many of them only consider trends in mean values, whereas it is clear, that not only means, but also whole shape of distribution changes over time and requires careful assessment. For example extreme values including outliers may get bigger, while median has zero slope.Quantile regression provides a convenient tool, that enables detailed analysis of changes in full range of distribution by producing a vector of quantile trends for any given set of quantiles.We have applied quantile regression to surface air temperature observations made at over 600 weather stations across Russian Federation during last four decades. The results demonstrate well pronounced regions with similar values of significant trends in different parts of temperature value distribution (left tail, middle part, right tail). The uncertainties of quantile trend estimations for several spatial patterns of trends over Russia are estimated and analyzed for each of four seasons.For temperature trend estimation over vast territories, quantile regression is an effort consuming approach, but is more informative than traditional instrument, to assess decadal evolution of temperature values, including evolution of extremes.Partial support of ERA NET RUS ACPCA joint project between EU and RBRF 12-05-91656-???-? is highly appreciated.

  2. Trends in furnace control

    SciTech Connect

    McDonald, T.J.; Keefe, M.D. . Instrumentation and Controls Dept.)

    1993-07-01

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

  3. 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}.

  4. Research trends in turbine aerodynamics.

    NASA Technical Reports Server (NTRS)

    Stewart, W. L.; Glassman, A. J.

    1972-01-01

    Brief description of some of the recent trends in turbine aerodynamics research. Areas covered include cooled turbine aerodynamics, high work-factor turbines, pneumatic variable geometry, and computer analysis. Most of this research is shown to have been directed primarily toward allowing the turbine to accept efficiently higher inlet temperatures and blade loading.

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

    SciTech Connect

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

    2013-03-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  7. NASA standard: Trend analysis techniques

    NASA Technical Reports Server (NTRS)

    1988-01-01

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

  8. Ground-based observations of Saturn's auroral ionosphere over three days: Trends in H3+ temperature, density and emission with Saturn local time and planetary period oscillation

    NASA Astrophysics Data System (ADS)

    O'Donoghue, James; Melin, Henrik; Stallard, Tom S.; Provan, G.; Moore, Luke; Badman, Sarah V.; Cowley, Stan W. H.; Baines, Kevin H.; Miller, Steve; Blake, James S. D.

    2016-01-01

    On 19-21 April 2013, the ground-based 10-m W.M. Keck II telescope was used to simultaneously measure H3+ emissions from four regions of Saturn's auroral ionosphere: (1) the northern noon region of the main auroral oval; (2) the northern midnight main oval; (3) the northern polar cap and (4) the southern noon main oval. The H3+ emission from these regions was captured in the form of high resolution spectral images as the planet rotated. The results herein contain twenty-three H3+ temperatures, column densities and total emissions located in the aforementioned regions - ninety-two data points in total, spread over timescales of both hours and days. Thermospheric temperatures in the spring-time northern main oval are found to be cooler than their autumn-time southern counterparts by tens of K, consistent with the hypothesis that the total thermospheric heating rate is inversely proportional to magnetic field strength. The main oval H3+ density and emission is lower at northern midnight than it is at noon, in agreement with a nearby peak in the electron influx in the post-dawn sector and a minimum flux at midnight. Finally, when arranging the northern main oval H3+ parameters as a function of the oscillation period seen in Saturn's magnetic field - the planetary period oscillation (PPO) phase - we see a large peak in H3+ density and emission at ?115° northern phase, with a full-width at half-maximum (FWHM) of ?44°. This seems to indicate that the influx of electrons associated with the PPO phase at 90° is responsible at least in part for the behavior of all H3+ parameters. A combination of the H3+ production and loss timescales and the ±10° uncertainty in the location of a given PPO phase are likely, at least in part, to be responsible for the observed peaks in H3+ density and emission occurring at a later time than the peak precipitation expected at 90° PPO phase.

  9. Drivers, Trends and Mitigation

    SciTech Connect

    Blanco, Arthur S.; Gerlagh, Reyer; Suh, Sangwon; Barrett, John A.; de Coninck, Heleen; Diaz Morejon, Cristobal Felix; Mathur, Ritu; Nakicenovic, Nebojsa; Ahenkorah, Alfred Ofosu; Pan, Jiahua; Pathak, Himanshu; Rice, Jake; Richels, Richard G.; Smith, Steven J.; Stern, David; Toth, Ferenc L.; Zhou, Peter

    2014-12-01

    Chapter 5 analyzes the anthropogenic greenhouse gas (GHG) emission trends until the present and the main drivers that explain those trends. The chapter uses different perspectives to analyze past GHG-emissions trends, including aggregate emissions flows and per capita emissions, cumulative emissions, sectoral emissions, and territory-based vs. consumption-based emissions. In all cases, global and regional trends are analyzed. Where appropriate, the emission trends are contextualized with long-term historic developments in GHG emissions extending back to 1750.

  10. A Hierarchical Bayesian Model to Quantify Uncertainty of Stream Water Temperature Forecasts

    PubMed Central

    Bal, Guillaume; Rivot, Etienne; Baglinière, Jean-Luc; White, Jonathan; Prévost, Etienne

    2014-01-01

    Providing generic and cost effective modelling approaches to reconstruct and forecast freshwater temperature using predictors as air temperature and water discharge is a prerequisite to understanding ecological processes underlying the impact of water temperature and of global warming on continental aquatic ecosystems. Using air temperature as a simple linear predictor of water temperature can lead to significant bias in forecasts as it does not disentangle seasonality and long term trends in the signal. Here, we develop an alternative approach based on hierarchical Bayesian statistical time series modelling of water temperature, air temperature and water discharge using seasonal sinusoidal periodic signals and time varying means and amplitudes. Fitting and forecasting performances of this approach are compared with that of simple linear regression between water and air temperatures using i) an emotive simulated example, ii) application to three French coastal streams with contrasting bio-geographical conditions and sizes. The time series modelling approach better fit data and does not exhibit forecasting bias in long term trends contrary to the linear regression. This new model also allows for more accurate forecasts of water temperature than linear regression together with a fair assessment of the uncertainty around forecasting. Warming of water temperature forecast by our hierarchical Bayesian model was slower and more uncertain than that expected with the classical regression approach. These new forecasts are in a form that is readily usable in further ecological analyses and will allow weighting of outcomes from different scenarios to manage climate change impacts on freshwater wildlife. PMID:25541732

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

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

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

  12. Version 8 SBUV Ozone Profile Trends Compared with Trends from a Zonally Averaged Chemical Model

    NASA Technical Reports Server (NTRS)

    Rosenfield, Joan E.; Frith, Stacey; Stolarski, Richard

    2004-01-01

    Linear regression trends for the years 1979-2003 were computed using the new Version 8 merged Solar Backscatter Ultraviolet (SBUV) data set of ozone profiles. These trends were compared to trends computed using ozone profiles from the Goddard Space Flight Center (GSFC) zonally averaged coupled model. Observed and modeled annual trends between 50 N and 50 S were a maximum in the higher latitudes of the upper stratosphere, with southern hemisphere (SH) trends greater than northern hemisphere (NH) trends. The observed upper stratospheric maximum annual trend is -5.5 +/- 0.9 % per decade (1 sigma) at 47.5 S and -3.8 +/- 0.5 % per decade at 47.5 N, to be compared with the modeled trends of -4.5 +/- 0.3 % per decade in the SH and -4.0 +/- 0.2% per decade in the NH. Both observed and modeled trends are most negative in winter and least negative in summer, although the modeled seasonal difference is less than observed. Model trends are shown to be greatest in winter due to a repartitioning of chlorine species and the increasing abundance of chlorine with time. The model results show that trend differences can occur depending on whether ozone profiles are in mixing ratio or number density coordinates, and on whether they are recorded on pressure or altitude levels.

  13. Snow in Castile-León: trends and variability

    NASA Astrophysics Data System (ADS)

    Merino, A.; Campos, L.; López, L.; García-Ortega, E.; Sánchez, J. L.; Marcos, J. L.; Guerrero-Higueras, A. M.

    2012-04-01

    The location of Castile and León, inside the Iberian Peninsula, in the Northwestern quadrant, determines, in large measure, the climatic conditions of its territory, granting it very characteristic traits, mostly in the mountainous areas. It is important to note that during a large part of the year, the region is under the influence of Jet Stream, and thus, gives way to very diverse dynamic situations, which turn into different and heterogeneous types of weather. So, in many areas of the region, especially in the most elevated areas, these synoptic and mesoscale situations generate snow precipitation. We should point out that snowfall is one of the principal meteorological risks of Castile and León. Thus, on average, in some mountainous areas there are more than 40 events of snowfall registered annually, with the month of January being the month in which the highest frequency of snowfall appears. The social repercussions of this snowfall are represented in the isolation of places, essentially mountainous, highways being blocked, increase in traffic accidents, etc. As proof of this, it is this type of episode that receives ample coverage by the media, which has a linear relationship with the social perception of risk. As such, the objective of the current work is to analyze the annual trend of days with snow in the different meteorological stations pertaining to AEMET placed in the Community. The period of study is from 1960-2010. Additionally, we have also evaluated trends in annual days of freezing temperature and annual absolute minimum temperature, with the objective of facilitating a meteorological interpretation of the trends obtained on days with snowfall. Finally, the results show that in the majority of stations, a significant negative trend in days with snowfall and annual days with freezing temperatures, and a positive trend in annual absolute minimum temperatures. However, we observed variability in the different regions in the area of study. Acknowledgements The authors would like to thank the Regional Government of Castile-León for its financial support through the project LE220A11-2. This study was supported by the following grants: CEN20091028; GRANIMETRO (CGL2010-15930); MICROMETEO (IPT-310000-2010-22 ).

  14. Breast Cancer Trends

    MedlinePLUS

    ... Kinds of Cancer Cervical Colorectal (Colon) Lung Ovarian Prostate Skin Cancer Home Breast Cancer Trends Language: English Español (Spanish) ... Native). Stay Informed Trends for Other Kinds of Cancer Cervical Colorectal ... Language: English Español (Spanish) File Formats Help: ...

  15. Marketing Trends to Watch

    ERIC Educational Resources Information Center

    Circle, Alison

    2009-01-01

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

  16. Trends in Education.

    ERIC Educational Resources Information Center

    School Planning & Management, 2002

    2002-01-01

    Several architects, planners, administrators, and contractors answer questions about trends related to school construction, interior design, business, security, and technology. Trends concern funding issues, specialized designs, planning for safety, technological integration, and equity in services. (EV)

  17. Linear Accelerators

    SciTech Connect

    Sidorin, Anatoly

    2010-01-05

    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.

  18. Future Trends Affecting Education.

    ERIC Educational Resources Information Center

    Good, Dixie Griffin

    This paper examines various trends and explores how they may affect education. Six specific trends are explored: (1) education trends, in which competition among schools for students, educators, and funds is increasing, calls for education accountability are increasing at all levels, and the demand for education professionals is rising; (2)…

  19. Confronting Climate Model Simulations with Satellite-Based Evaluation of Warm Rain Formation: Can We Reconcile "Bottom-up" Process-Based Constraints with the "Top-Down" Temperature Trend Constraints?

    NASA Astrophysics Data System (ADS)

    Golaz, J. C.; Suzuki, K.; Guo, H.

    2014-12-01

    Cloud parameterizations in climate models include a number of adjustable parameters that arise from uncertainties in cloud processes. These parameters are often tuned to best reproduce specific aspects of the observed climate, such as the energy balance at the top of the atmosphere. Starting with the CMIP5 GFDL CM3 coupled climate model, we construct alternate model configurations that achieve the desired energy balance using different, but plausible, combinations of parameters. The present-day climate is nearly indistinguishable in all configurations, but the evolution of the surface temperature from pre-industrial to present-day differs markedly among these configurations due to a large spread in the magnitude of the aerosol indirect effect. Details of the cloud-to-rain conversion processes are found to be the source for this large spread. Recently developed methodologies to analyze the CloudSat and A-Train satellite observations are employed to construct the statistical "fingerprint" process-level signatures of the cloud-to-rain processes. These methodologies are applied to both satellite observations and climate models. Such comparisons can be used to help constrain uncertain parameters included in cloud parameterizations. One of the highlighted results demonstrates that the model predictability of twentieth-century historical temperature trends contradicts the process-based constraint on a tunable cloud parameter. This implies the presence of compensating errors at a fundamental level, and underscores the importance of observation-based, process-level constraints on model microphysics uncertainties for more reliable predictions of the aerosol indirect effect. This uncertainty in the magnitude of the aerosol indirect effect ultimately limits our ability to constrain the climate sensitivity.

  20. Trends and drivers in global surface ocean pH over the past 3 decades

    NASA Astrophysics Data System (ADS)

    Lauvset, S. K.; Gruber, N.; Landschützer, P.; Olsen, A.; Tjiputra, J.

    2015-03-01

    We report global long-term trends in surface ocean pH using a new pH data set computed by combining fCO2 observations from the Surface Ocean CO2 Atlas (SOCAT) version 2 with surface alkalinity estimates based on temperature and salinity. Trends were determined over the periods 1981-2011 and 1991-2011 for a set of 17 biomes using a weighted linear least squares method. We observe significant decreases in surface ocean pH in ~70% of all biomes and a mean rate of decrease of 0.0018 ± 0.0004 yr-1 for 1991-2011. We are not able to calculate a global trend for 1981-2011 because too few biomes have enough data for this. In half the biomes, the rate of change is commensurate with the trends expected based on the assumption that the surface ocean pH change is only driven by the surface ocean CO2 chemistry remaining in a transient equilibrium with the increase in atmospheric CO2. In the remaining biomes, deviations from such equilibrium may reflect that the trend of surface ocean fCO2 is not equal to that of the atmosphere, most notably in the equatorial Pacific Ocean, or may reflect changes in the oceanic buffer (Revelle) factor. We conclude that well-planned and long-term sustained observational networks are key to reliably document the ongoing and future changes in ocean carbon chemistry due to anthropogenic forcing.

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

    SciTech Connect

    Derksen, C.; Piwowar, J.; Sokol, J.; LeDrew, E.

    1997-08-01

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

  2. The first near-linear bis(amide) f-block complex: a blueprint for a high temperature single molecule magnet.

    PubMed

    Chilton, Nicholas F; Goodwin, Conrad A P; Mills, David P; Winpenny, Richard E P

    2015-01-01

    We report the first near-linear bis(amide) 4f-block compound and show that this novel structure, if implemented with dysprosium(III), would have unprecedented single molecule magnet (SMM) properties with an energy barrier, Ueff, for reorientation of magnetization of 1800 cm(-1). PMID:25384179

  3. Spatio-temporal Trends of Climate Variability in North Carolina

    NASA Astrophysics Data System (ADS)

    Sayemuzzaman, Mohammad

    Climatic trends in spatial and temporal variability of maximum temperature (Tmax), minimum temperature (Tmin), mean temperature (Tmean) and precipitation were evaluated for 249 ground-based stations in North Carolina for 1950-2009. The Mann-Kendall (MK), the Theil-Sen Approach (TSA) and the Sequential Mann-Kendall (SQMK) tests were applied to quantify the significance of trend, magnitude of trend and the trend shift, respectively. The lag-1 serial correlation and double mass curve techniques were used to address the data independency and homogeneity. The pre-whitening technique was used to eliminate the effect of auto correlation of the data series. The difference between minimum and maximum temperatures, and so the diurnal temperature range (DTR), at some stations was found to be decreasing on both an annual and a seasonal basis, with an overall increasing trend in the mean temperature. For precipitation, a statewide increasing trend in fall (highest in November) and decreasing trend in winter (highest in February) were detected. No pronounced increasing/decreasing trends were detected in annual, spring, and summer precipitation time series. Trend analysis on a spatial scale (for three physiographic regions: mountain, piedmont and coastal) revealed mixed results. Coastal zone exhibited increasing mean temperature (warming) trend as compared to other locations whereas mountain zone showed decreasing trend (cooling). Three main moisture components (precipitation, total cloud cover, and soil moisture) and the two major atmospheric circulation modes (North Atlantic Oscillation and Southern Oscillation) were used for correlative analysis purposes with the temperature (specifically with DTR) and precipitation trends. It appears that the moisture components are associated with DTR more than the circulation modes in North Carolina.

  4. Temperature dependence of superfluid density in YBa 2Cu 3O 7- ? and Y 0.7Ca 0.3Ba 2Cu 3O 7- ? thin films: A doping dependence study of the linear slope

    NASA Astrophysics Data System (ADS)

    Lai, L. S.; Juang, J. Y.; Wu, K. H.; Uen, T. M.; Gou, Y. S.

    2005-11-01

    By using a microstrip ring resonator to measure the temperature dependence of the in-plane magnetic penetration depth ?(T) in YBa2Cu3O7-? (YBCO) and Y0.7Ca0.3Ba2Cu3O7-? (Ca-YBCO) epitaxially grown thin films, the linear temperature dependence of the superfluid density ?s/m? ? 1/?2(T) was observed from the under- to the overdoped regime at the temperatures below T/Tc ? 0.3 . For the underdoped regime of YBCO and Ca-YBCO thin films, the magnitude of the slope d(1/?2(T))/dT is insensitive to doping, and it can be treated in the framework of projected d-density-wave model. Combining these slope values with the thermal conductivity measurements, the Fermi-liquid correction factor ?2 from the Fermi-liquid model, suggested by Wen and Lee, was revealed here with various doping levels.

  5. On trend estimation and significance testing for non-Gaussian and serially dependent data: quantifying the urbanization effect on trends in hot extremes in the megacity of Shanghai

    NASA Astrophysics Data System (ADS)

    Qian, Cheng

    2015-09-01

    Quantifying the urbanization effect on trends in climate extremes is important both for detection and attribution studies and for human adaptation; however, a fundamental problem is how to accurately estimate a trend and its statistical significance, especially for non-Gaussian and serially dependent data. In this paper, the choice of trend estimation and significance testing method is suggested as important for these kinds of studies, as illustrated by quantifying the urbanization effect on trends in seven hot-extreme indices for the megacity of Shanghai during 1961-2013. Both linear and nonlinear trend estimation methods were used. The trends and corresponding statistical significances were estimated by taking into account potential non-Gaussian and serial dependence in the extreme indices. A new method based on adaptive surrogate data is proposed to test the statistical significance of the ensemble empirical mode decomposition (EEMD) nonlinear trend. The urbanization contribution was found to be approximately 34 % (43 %) for the trend in the non-Gaussian distributed heat wave index based on nonparametric linear trend (EEMD nonlinear trend) estimation. For some of the other six hot-extreme indices analyzed, the urbanization contributions estimated based on linear and nonlinear trends varied greatly, with as much as a twofold difference between them. For the linear trend estimation itself, the ordinary least squares fit can give a substantially biased estimation of the urbanization contribution for some of the non-Gaussian extreme indices.

  6. Linear Collisions

    ERIC Educational Resources Information Center

    Walkiewicz, T. A.; Newby, N. D., Jr.

    1972-01-01

    A discussion of linear collisions between two or three objects is related to a junior-level course in analytical mechanics. The theoretical discussion uses a geometrical approach that treats elastic and inelastic collisions from a unified point of view. Experiments with a linear air track are described. (Author/TS)

  7. Future trends in regulation

    SciTech Connect

    Remick, F.J.

    1993-12-31

    This report presents a discussion on the future of nuclear regulations and what regulators should strive for. The following 6 trends are described: the regulatory presence around the world will grow; there is a trend towards giving the regulator greater independence; there is a trend toward greater self-regulation by the industry; less prescriptive regulation; regulators may be converging no a quantitative risk goal; increasing recognition of the importance of stability in the regulator.

  8. Short-term Aerosol Trends: Reality or Myth?

    NASA Technical Reports Server (NTRS)

    Leptoukh, Gregory; Zubko, Viktor

    2009-01-01

    The main questions addressed in this slide presentation involve short-term trends of MODIS aerosol optical thickness (AOT) over 6 years: (1) Why are the trends different in different regions? (2) How are these trends so high? (3) Why are they "coherent" in many areas? (4) Are these changes in aerosol concentrations real, i.e., are they monotonic changes in emissions? Several views of the Spatial Distribution of AOT from Terra are shown. In conclusion there are several trends: (1) There is a broad spatial inhomogenueity in AOT trends over 6 years of MODIS Terra and Aqua (2) Some of the areas demonstrate clear positive trends related to increase of emission (e.g., Eastern China) (3) Strong trends in some other areas are superficial and might be attributed, in part, to: (3a) Least squares linear trend sensitivity to outliers (need to use more robust linear fitting method) (3b) Spatial and temporal shifts or trends in meteorological conditions, especially in wind patterns responsible for aerosol transport (6) Aerosol trends should be studied together with changes in meteorology patterns as they might closely linked together

  9. Extreme temperature indices analyses: A case study of five meteorological stations in Peninsular Malaysia

    NASA Astrophysics Data System (ADS)

    Hasan, Husna; Salleh, Nur Hanim Mohd

    2015-10-01

    Extreme temperature events affect many human and natural systems. Changes in extreme temperature events can be detected and monitored by developing the indices based on the extreme temperature data. As an effort to provide the understanding of these changes to the public, a study of extreme temperature indices is conducted at five meteorological stations in Peninsular Malaysia. In this study, changes in the means and extreme events of temperature are assessed and compared using the daily maximum and minimum temperature data for the period of 2004 to 2013. The absolute extreme temperature indices; TXx, TXn, TXn and TNn provided by Expert Team on Climate Change Detection and Indices (ETCCDI) are utilized and linear trends of each index are extracted using least square likelihood method. The results indicate that there exist significant decreasing trend in the TXx index for Kota Bharu station and increasing trend in TNn index for Chuping and Kota Kinabalu stations. The comparison between the trend in mean and extreme temperatures show the same significant tendency for Kota Bharu and Kuala Terengganu stations.

  10. TRENDS IN ADULT READING.

    ERIC Educational Resources Information Center

    MILLER, JUSTIN H.

    TRENDS EVIDENT IN ADULT READING DURING THE 1960'S IN THE AREAS OF ADMINISTRATION, PROGRAMS, TEACHING, TECHNIQUES, RESEARCH PROJECTS, AND METHODS OF PROMOTION OF READING PROGRAMS ARE DISCUSSED. TWO INSTANCES OF COMMERCIAL EXPLOITATION BASED ON INTENSE AND OFTEN FALLACIOUS ADVERTISING AND ON PUBLIC IGNORANCE ARE CITED. A POSITIVE TREND IN THE AREA…

  11. Some Current Population Trends.

    ERIC Educational Resources Information Center

    Taeuber, Conrad

    Population trends in the 1960's and early 1970's are examined in this 1972 speech in terms of overall national trends, the growth of metropolitan areas, the rural population, geographic shifts, internal migration, the black population, and living arrangements. It is noted that population growth in the 1960's was unevenly distributed within age…

  12. Trends Shaping Education 2010

    ERIC Educational Resources Information Center

    OECD Publishing (NJ3), 2010

    2010-01-01

    "Trends Shaping Education 2010" brings together evidence showing the effects on education of globalisation, social challenges, changes in the workplace, the transformation of childhood, and ICT. To make the content accessible, each trend is presented on a double page, containing an introduction, two charts with brief descriptive text and a set of…

  13. General Achievement Trends: Massachusetts

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  14. General Achievement Trends: Idaho

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  15. General Achievement Trends: Nebraska

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  16. General Achievement Trends: Oklahoma

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  17. General Achievement Trends: Hawaii

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  18. General Achievement Trends: Iowa

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  19. General Achievement Trends: Arkansas

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  20. General Achievement Trends: Texas

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  1. General Achievement Trends: Alabama

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  2. General Achievement Trends: Virginia

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  3. General Achievement Trends: Florida

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  4. General Achievement Trends: Georgia

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  5. General Achievement Trends: Michigan

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  6. General Achievement Trends: Kentucky

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  7. General Achievement Trends: Colorado

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  8. General Achievement Trends: Maine

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  9. General Achievement Trends: Maryland

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  10. General Achievement Trends: Oregon

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  11. General Achievement Trends: Tennessee

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

  12. General Achievement Trends: Kansas

    ERIC Educational Resources Information Center

    Center on Education Policy, 2009

    2009-01-01

    This general achievement trends profile includes information that the Center on Education Policy (CEP) and the Human Resources Research Organization (HumRRO) obtained from states from fall 2008 through April 2009. Included herein are: (1) Bullet points summarizing key findings about achievement trends in that state at three performance…

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

    E-print Network

    Scafetta, Nicola

    2014-01-01

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

  14. Temperature Calibration

    NASA Astrophysics Data System (ADS)

    Wang, A. L.

    2013-12-01

    Accuracy of temperature measurements is vital to many experiments. In this project, we design an algorithm to calibrate thermocouples' temperature measurements. To collect data, we rely on incremental heating to calculate the diffusion coefficients of argon through sanidine glasses. These coefficients change according to an arrhenius equation that depends on temperature, time, and the size and geometry of the glass; thus by fixing the type of glass and the time of each heating step, we obtain many data points by varying temperature. Because the dimension of temperature is continuous, obtaining data is simpler in noble gas diffusion experiments than in measuring the discrete melting points of various metals. Due to the nature of electrical connections, the need to reference to the freezing point of ice, thermal gradients in the sample, the time dependent dissipation of heat into the surroundings, and other inaccuracies with thermocouple temperature measurements, it is necessary to calibrate the experimental measurements with the expected or theoretical measurements. Since the diffusion constant equation is exponential with the inverse of temperature, we transform the exponential D vs T graph into a linear log(D) vs 1/T graph. Then a simple linear regression yields the equation of the line, and we find a mapping function from the experimental temperature to the expected temperature. By relying on the accuracy of the diffusion constant measurement, the mapping function provides the temperature calibration. Theoretical (Temperature, Diffusion Coefficient, Fractional Loss, Zeta)

  15. Record occurrence and record values in daily and monthly temperatures

    E-print Network

    Wergen, Gregor; Krug, Joachim

    2012-01-01

    We analyze the occurrence and the values of record-breaking temperatures in daily and monthly temperature observations. Our aim is to better understand and quantify the statistics of temperature records in the context of global warming. Similar to earlier work we employ a simple mathematical model of independent and identically distributed random variables with a linearly growing expectation value. This model proved to be useful in predicting the increase (decrease) in upper (lower) temperature records in a warming climate. Using both station and re-analysis data from Europe and the United States we further investigate the statistics of temperature records and the validity of this model. The most important new contribution in this article is an analysis of the statistics of record values for our simple model and European reanalysis data. We estimate how much the mean values and the distributions of record temperatures are affected by the large scale warming trend. In this context we consider both the values o...

  16. Time series modeling and central European temperature impact assessment of phenological records over the last 250 years

    NASA Astrophysics Data System (ADS)

    Schleip, Christoph; Rutishauser, This; Luterbacher, Jürg; Menzel, Annette

    2008-12-01

    Long-term spring and autumn phenological observations from Switzerland and Burgundy (eastern France) as well as long-term Swiss monthly and seasonal temperature measurements offer a unique possibility to evaluate plant phenological variability and temperature impacts over the last 250 years. We compare Pearson correlation coefficients and linear moving window trends of two different lengths with a Bayesian correlation and model comparison approach. The latter is applied to calculate model probabilities, change-point probabilities, functional descriptions, and rates of change of three selected models with increasing complexity and temperature weights of single months. Both approaches, the moving window trends as well as the Bayesian analysis, detect major changes in long-term phenological and temperature time series at the end of the 20th century. Especially for summer temperatures since the 1980s, Bayesian model-averaged trends reveal a warming rate that increased from an almost zero rate of change to an unprecedented rate of change of 0.08°C/a in 2006. After 1900, temperature series of all seasons show positive model-averaged trends. In response to this temperature increase, the onset of phenology advanced significantly. We assess the linear dependence of phenological variability by a linear Pearson correlation approach. In addition we apply the Bayesian correlation to account for nonlinearities within the time series. Grape harvest dates show the highest Bayesian correlations with June temperatures of the current year. Spring phenological phases are influenced by May temperatures of the current year and summer temperatures of the preceding growing season. For future work we suggest testing increasingly complex time series models such as multiple change-point models.

  17. Record occurrence and record values in daily and monthly temperatures

    NASA Astrophysics Data System (ADS)

    Wergen, G.; Hense, A.; Krug, J.

    2014-03-01

    We analyze the occurrence and the values of record-breaking temperatures in daily and monthly temperature observations. Our aim is to better understand and quantify the statistics of temperature records in the context of global warming. Similar to earlier work we employ a simple mathematical model of independent and identically distributed random variables with a linearly growing expectation value. This model proved to be useful in predicting the increase (decrease) in upper (lower) temperature records in a warming climate. Using both station and re-analysis data from Europe and the United States we further investigate the statistics of temperature records and the validity of this model. The most important new contribution in this article is an analysis of the statistics of record values for our simple model and European reanalysis data. We estimate how much the mean values and the distributions of record temperatures are affected by the large scale warming trend. In this context we consider both the values of records that occur at a certain time and the values of records that have a certain record number in the series of record events. We compare the observational data both to simple analytical computations and numerical simulations. We find that it is more difficult to describe the values of record breaking temperatures within the framework of our linear drift model. Observations from the summer months fit well into the model with Gaussian random variables under the observed linear warming, in the sense that record breaking temperatures are more extreme in the summer. In winter however a significant asymmetry of the daily temperature distribution hides the effect of the slow warming trends. Therefore very extreme cold records are still possible in winter. This effect is even more pronounced if one considers only data from subpolar regions.

  18. Study of structural break points in global and hemispheric temperature series by piecewise regression

    NASA Astrophysics Data System (ADS)

    Werner, Rolf; Valev, Dimitar; Danov, Dimitar; Guineva, Veneta

    2015-12-01

    The study of climate trends taking into consideration possible structural changes is important for understanding climate development characterized by a stochastic trend or by a determined one. In the paper global and hemisphere temperature anomalies are modeled by piecewise linear regression and break points in the temperature evolution are found. It was demonstrated that the used method allowed finding of breaks characterized by long time trends (low frequency processes) as well as abrupt changes (fast frequency processes). The obtained break points for slow temperature change are close to the ones found by other authors however additional conditions (as segment length, gradient and others) are not used here. The results for higher break point numbers are like the ones of step slope models. It was demonstrated that the successive phases of warming and cooling and most of the break points subdividing these periods in the Northern Hemisphere are introduced by the Atlantic multidecadal oscillation. Because the strong quasi periodicity of the Atlantic multidecadal oscillation the authors recommend the removal of its influence on the temperature from the temperature series before studies of trends or structural changes. The Northern Hemisphere temperature data after the removal of the Atlantic multidecadal oscillation influence show structures like the Southern Hemisphere temperatures. Model selection by the Schwarz-Bayesian Information Criterion developed by Liu, Wu and Zidek (LWZ criterion) shows that models with only one break point are to be preferred.

  19. Ovarian Cancer Trends

    MedlinePLUS

    ... Lung Prostate Skin Cancer Home Ovarian Cancer Trends Language: English Español (Spanish) Recommend on Facebook Tweet Share Compartir ... Cancer Breast Cervical Colorectal (Colon) Lung Prostate Skin Language: English Español (Spanish) File Formats Help: How do I ...

  20. Skin Cancer Trends

    MedlinePLUS

    ... Search The CDC Cancel Submit Search The CDC Skin Cancer Note: Javascript is disabled or is not ... Cervical Colorectal (Colon) Lung Ovarian Prostate Cancer Home Skin Cancer Trends Language: English Español (Spanish) Recommend on ...

  1. TREND DATA 1971 - 1995

    EPA Science Inventory

    Trend Data provides information up to 25 years of Veteran Data. Included are social and economic information about veterans, demographical and geographical veteran information, statistical information by veteran program areas and veteran survey information as well as references t...

  2. Bomber design trends

    NASA Technical Reports Server (NTRS)

    Spearman, M. L.

    1986-01-01

    Some basic trends in bomber aircraft are traced from the pre-World War I era to the present time. The historic review includes bombers of many countries. The primary discussion, however, will be based on U.S. bomber programs and, to the extent possible, on USSR bomber programs. The bomber aircraft will be examined in terms of performance and mission capability.Characteristics will include power or thrust loading, wing loading, maximum speed, cruising speed, weight and weight distribution, and payload. These trends can be used to indicate the rationale for certain design types. Performance characteristics can be used to indicate potential mission objectives. The overall design trends should be useful in revealing the influence of mission objectives, the influence of advanced technology and, in turn, may be useful in predicting likely future trends.

  3. Trends in Education.

    ERIC Educational Resources Information Center

    Snyder, Thomas D.; Freeman, Catherine E.

    2003-01-01

    Presents several key findings from several recent National Center for Educational Statistics reports related national trends in education involving elementary school enrollment, poverty concentration, language minority students, student family characteristics, reading comprehension, academic achievement (math, science, geography), student access…

  4. Historical Trends Graph

    Cancer.gov

    Use this graph to explore the relationship over time of levels and trends in cancer rates for geographic areas and for demographic subgroups. Potential health disparities can be explored to identify opportunities or to evaluate the success of prior interventions.

  5. Lung Cancer Trends

    MedlinePLUS

    ... Cervical Colorectal (Colon) Ovarian Prostate Skin Cancer Home Lung Cancer Trends Language: English Español (Spanish) Recommend on Facebook ... in the United States, the incidence rate of lung cancer— Men Decreased significantly by 2.4% per year ...

  6. Mathematical model for predicting topographical properties of poly (?-caprolactone) melt electrospun scaffolds including the effects of temperature and linear transitional speed

    NASA Astrophysics Data System (ADS)

    Ko, Junghyuk; Khadem Mohtaram, Nima; Lee, Patrick C.; Willerth, Stephanie M.; Jun, Martin B. G.

    2015-04-01

    Melt electrospinning can be used to fabricate various fibrous biomaterial scaffolds with a range of mechanical properties and varying topographical properties for different applications such as tissue scaffold and filtration and etc, making it a powerful technique. Engineering the topography of such electrospun microfibers can be easily done by tuning the operational parameters of this process. Recent experimental studies have shown promising results for fabricating various topographies, but there is no body of work that focuses on using mathematical models of this technique to further understand the effect of operational parameters on these properties of microfiber scaffolds. In this study, we developed a novel mathematical model using numerical simulations to demonstrate the effect of temperature, feed rate and flow rate on controlling topographical properties such as fiber diameter of these spun fibrous scaffolds. These promising modelling results are also compared to our previous and current experimental results. Overall, we show that our novel mathematical model can predict the topographical properties affected by key operational parameters such as change in temperature, flow rate and feed rate, and this model could serve as a promising strategy for the controlling of topographical properties of such structures for different applications.

  7. Rising air and stream-water temperatures in Chesapeake Bay region, USA

    USGS Publications Warehouse

    Rice, Karen C.; Jastram, John D.

    2015-01-01

    Monthly mean air temperature (AT) at 85 sites and instantaneous stream-water temperature (WT) at 129 sites for 1960–2010 are examined for the mid-Atlantic region, USA. Temperature anomalies for two periods, 1961–1985 and 1985–2010, relative to the climate normal period of 1971–2000, indicate that the latter period was statistically significantly warmer than the former for both mean AT and WT. Statistically significant temporal trends across the region of 0.023 °C per year for AT and 0.028 °C per year for WT are detected using simple linear regression. Sensitivity analyses show that the irregularly sampled WT data are appropriate for trend analyses, resulting in conservative estimates of trend magnitude. Relations between 190 landscape factors and significant trends in AT-WT relations are examined using principal components analysis. Measures of major dams and deciduous forest are correlated with WT increasing slower than AT, whereas agriculture in the absence of major dams is correlated with WT increasing faster than AT. Increasing WT trends are detected despite increasing trends in streamflow in the northern part of the study area. Continued warming of contributing streams to Chesapeake Bay likely will result in shifts in distributions of aquatic biota and contribute to worsened eutrophic conditions in the bay and its estuaries.

  8. Sharper detection of winter temperature changes in the Romanian higher-elevations

    NASA Astrophysics Data System (ADS)

    Croitoru, Adina-Eliza; Drignei, Dorin; Dragot?, Carmen Sofia; Imecs, Zoltan; Burada, Doina Cristina

    2014-11-01

    This paper investigates winter temperature trends in the Romanian higher-altitude areas, for three types of topographies: depression, slope and summit. The main challenge is that some winter temperature trends, by comparison with the other seasons, are milder and harder to detect. We used a change-point regression model with statistically dependent errors and compared it with a standard change-point model with independent errors. Statistical theory ensures that the former model gives a more accurate trend analysis than the latter. The model with statistically dependent errors detects change-points in the mid 70s and statistically significant increasing trends both before and after the change-point. On the other hand, the model with independent errors does not detect statistically significant increasing trends after the change-points for the winter series. These general results occur for all topography types. A separate multiple regression model reveals that the winter temperature trend changes in the Romanian higher-elevations can be described by a linear additive effect of several global atmospheric circulation patterns.

  9. Ozone Trend Detectability

    NASA Technical Reports Server (NTRS)

    Campbell, J. W. (editor)

    1981-01-01

    The detection of anthropogenic disturbances in the Earth's ozone layer was studied. Two topics were addressed: (1) the level at which a trend in total ozoning is detected by existing data sources; and (2) empirical evidence in the prediction of the depletion in total ozone. Error sources are identified. The predictability of climatological series, whether empirical models can be trusted, and how errors in the Dobson total ozone data impact trend detectability, are discussed.

  10. Total solar irradiance trend during solar cycles 21 and 22.

    NASA Astrophysics Data System (ADS)

    Willson, R. C.

    1997-09-01

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

  11. Crop-climate relationships of cereals in Greece and the impacts of recent climate trends

    NASA Astrophysics Data System (ADS)

    Mavromatis, Theodoros

    2015-05-01

    Notwithstanding technological developments, agricultural production is still affected by uncontrollable factors, such weather and climate. Within this context, the present study aims at exploring the relative influence of growing season climate on the yields of major cereals (hard and soft wheat, maize, and barley) on a regional scale in Greece. To this end, crop-climate relationships and the impacts of climate trends over the period 1978-2005 were explored using linear regression and change point analysis (CPA). Climate data used include maximum (Tx) and minimum temperature (Tn), diurnal temperature range (Tr), precipitation (Prec), and solar radiation (Rad). Temperature effects were the most substantial. Yields reduced by 1.8-7.1 %/°C with increasing Tx and by 1.4-6.1 %/°C with decreasing Tr. The warming trends of Tn caused bilateral yield effects (from -3.7 to 8.4 %/°C). The fewer significantly increasing Rad and decreasing Prec anomalies were associated with larger yield decreases (within the range of 2.2 % MJ/m2/day (for maize) to 4.9 % MJ/m2/day (for hard wheat)) and smaller yield increases (from 0.04 to 1.4 %/mm per decade), respectively. Wheat and barley—the most vulnerable cereals—were most affected by the trends of extreme temperatures and least by Tr. On the contrary, solar radiation has proven to be the least affecting climate variable on all cereals. Despite the similarity in the direction of crop responses with both analyses, yield changes were much more substantial in the case of CPA analysis. In conclusion, regional climate change has affected Greek cereal productivity, in a few, but important for cereal production, regions. The results of this study are expected to be valuable in anticipating the effects of weather/climate on other warm regions worldwide, where the upper temperature limit for some cereals and further changes in climate may push them past suitability for their cultivation.

  12. Trends at a Glance | Cancer Trends Progress Report

    Cancer.gov

    The Trends-at-a-Glance offers an overview of trend direction measure by measure. Trends noted as stable or NSC (non-significant change) are not changing significantly. The difference between "stable" and "NSC" is based on statistical computations described in the Methodology for Characterizing Trends appendix.

  13. Influence of temperature changes on migraine occurrence in Germany

    NASA Astrophysics Data System (ADS)

    Scheidt, Jörg; Koppe, Christina; Rill, Sven; Reinel, Dirk; Wogenstein, Florian; Drescher, Johannes

    2013-07-01

    Many factors trigger migraine attacks. Weather is often reported to be one of the most common migraine triggers. However, there is little scientific evidence about the underlying mechanisms and causes. In our pilot study, we used smartphone apps and a web form to collect around 4,700 migraine messages in Germany between June 2011 and February 2012. Taking interdiurnal temperature changes as an indicator for changes in the prevailing meteorological conditions, our analyses were focused on the relationship between temperature changes and the frequency of occurrence of migraine attacks. Linear trends were fitted to the total number of migraine messages with respect to temperature changes. Statistical and systematic errors were estimated. Both increases and decreases in temperature lead to a significant increase in the number of migraine messages. A temperature increase (decrease) of 5 °C resulted in an increase of 19 ± 7 % (24 ± 8 %) in the number of migraine messages.

  14. European drought trends

    NASA Astrophysics Data System (ADS)

    Gudmundsson, L.; Seneviratne, S. I.

    2015-06-01

    Recent climate projections suggest pronounced changes in European drought frequency. In the north, increased precipitation volumes are likely to reduce drought occurrence, whereas more frequent droughts are expected for southern Europe. To assess whether this pattern of changes in drought frequency can already be identified for the past decades, we analyse trends in a recently developed pan-European drought climatology that is based on the Standardized Precipitation Index (SPI). The index is derived on multiple time scales, ranging from 1 to 36 months, which allows the assessment of trends in both short term and multi-year droughts. Trends are quantified using the Theil-Sen trend estimator combined with an extension of the Mann-Kendal test (p < 0.05) that accounts for serial correlation. Field significance is assessed on the basis of techniques that control the false discovery rate in a multiple testing setting. The trend analysis indicates that changes in drought frequency are more pronounced on time scales of one year and longer. The analysis also reveals that there has been a tendency for decreased drought frequency in northern Europe in the past decades, whereas droughts have likely become more frequent in selected southern regions.

  15. Supply Chain Trends Sunil Chopra

    E-print Network

    Chen, Wei

    © Chopra 1 Supply Chain Trends Sunil Chopra Kellogg School of Management #12;Supply Chain Trends © Chopra / OPNS 455 / Transportation 2 #12;© Chopra / OPNS 455 / Transportation 3 Supply Chain Trends East. Financial Mail (South Africa, March 28, 2008) #12;Supply Chain Trends - Globalization How to use

  16. A probabilistic method of calculating circulation-induced trends

    NASA Astrophysics Data System (ADS)

    Brox Nilsen, Irene; Stagge, James Howard; Merete Tallaksen, Lena

    2015-04-01

    The water cycle in Europe has changed substantially over the past three decades. Increasing runoff is observed during winter and at northern latitudes in particular. Spring and summer months, as well as southern latitudes, are facing drier conditions. To understand what is driving large-scale changes in runoff, we look into changes in precipitation and temperature and link these to changes in atmospheric circulation. Previous studies have used the method of trend ratios (Cahynová and Huth, 2009) to attribute precipitation and temperature trends to changes in the frequency of circulation types. A trend ratio is the ratio of hypothetical trend, i.e., the trend that would result due to changes in circulation type frequency only, to the observed trend. However, the method of trend ratios has two drawbacks. First, if the observed trend is small, division by a very low value results in a meaningless trend ratio and thus requires a cut-off value to keep the trend ratio within meaningful boundaries. Second, the method does not allow a comparison of the observed trend to the spread of possible outcomes, because the method of hypothetical trends is based on a deterministic model. We propose a new, more robust method for detecting the importance of circulation-induced changes in explaining the observed trends, which has the benefit of being a non-parametric statistical test that assesses the entire range of hypothetical trends. Instead of creating a hypothetical series by replacing the observation on a given day with the long-term climatic mean of a certain month and circulation type (as in the existing trend ratio method), the new approach replaces the observation on a given day with a random sample from the distribution of the variable for the given month and circulation type. The method introduces the possibility to assign a rejection rate, thus allowing statistical significance to be assessed. We apply the method on time series of precipitation and temperature from the gridded 0.5 degree WFDEI dataset, covering Europe (40-65N, 10W-30E). The SynopVis Grosswetterlagen catalogue of circulation types for the time period 1981-2010, the same period as the climatic data, is used. The new approach is used to map in which regions and months changes in atmospheric circulation is the dominating factor controlling changes in precipitation and temperature in Europe. References Cahynová, M. and R. Huth (2009). Changes of atmospheric circulation in central Europe and their influence on climatic trends in the Czech Republic. Theoretical and Applied Climatology 96, 57-68. DOI:10.1007/s00704-008-0097-2.

  17. Crystal structures of the high temperature forms of V{sub 8}O{sub 15} and V{sub 9}O{sub 17} and structural trends in the V{sub n}O{sub 2n-1} Magneli series

    SciTech Connect

    Allred, J.M.; Cava, R.J.

    2013-02-15

    We report the structure of the metallic high-temperature (ht) form of V{sub 9}O{sub 17}, determined from single crystal X-ray diffraction: space group=P-1 a=5.4219(7) A, b=7.0142(9) A, c=14.5252(19) A, {alpha}=97.0310(10) Degree-Sign , {beta}=90.9900(10) Degree-Sign , {gamma}=108.9630(10) Degree-Sign , V=517.53(12) A{sup 3}, and Z=2. We also report refinement of the structure of metallic ht-V{sub 8}O{sub 15}, space group=P-1, a=5.4315(17) A, b=7.015(2) A, c=13.147(5) A, {alpha}=100.144(4) Degree-Sign , {beta}=95.776(4) Degree-Sign , {gamma}=108.965(3) Degree-Sign , V=459.6(3) A{sup 3}, and Z=2. The structure of metallic V{sub 9}O{sub 17} is interpreted and discussed in the context of the V{sub n}O{sub 2n-1} Magneli phases, yielding trends about how the underlying forces contribute to the metal to insulator transition (MIT). The manner in which structural features of the metallic phases change as a function of n supports previous arguments that there is a turnover in the forces leading to the MIT between n=6 and n=8. - Graphical abstract: Left: The crystal structures of V{sub 8}O{sub 15} and V{sub 9}O{sub 17} shown in context of the crystallographic shear family V{sub n}O{sub 2n-1}. Right: The lattice parameters of V{sub n}O{sub 2n-1} as a function of n. The anamolous trend in b exhibits similar behavior as the metal to insulator (MIT) transition temperature (red). Highlights: Black-Right-Pointing-Pointer Crystal structures of the metallic forms of V{sub 8}O{sub 15} and V{sub 9}O{sub 17}. Black-Right-Pointing-Pointer General trends across the V{sub n}O{sub 2n-1} allow designation of two chain types in all phases. Black-Right-Pointing-Pointer Triclinic b lattice parameter varies anomalously with n, in V{sub n}O{sub 2n-1}. Black-Right-Pointing-Pointer Trend in b matches the metal to insulator transition temperature trend.

  18. Trends in source gases

    NASA Technical Reports Server (NTRS)

    Ehhalt, D. H.; Fraser, P. J.; Albritton, D.; Cicerone, R. J.; Khalil, M. A. K.; Legrand, M.; Makide, Y.; Rowland, F. S.; Steele, L. P.; Zander, R.

    1989-01-01

    Source gases are defined as those gases that, by their breakdown, introduce into the stratosphere halogen, hydrogen, and nitrogen compounds that are important in stratospheric ozone destruction. Given here is an update of the existing concentration time series for chlorocarbons, nitrous oxide, and methane. Also reviewed is information on halogen containing species and the use of these data for establishing trends. Also reviewed is evidence on trends in trace gases that influence tropospheric chemistry and thus the tropospheric lifetimes of source gases, such as carbon dioxide, carbon monoxide, or nitrogen oxides. Much of the information is given in tabular form.

  19. Some fighter aircraft trends

    NASA Technical Reports Server (NTRS)

    Spearman, L.

    1985-01-01

    Some basic trends in fighters are traced from the post World II era. Beginning with the first operational jet fighter, the P-80, the characteristics of subsequent fighter aircraft are examined for performance, mission capability, effectiveness, and cost. Characteristics presented include: power loading, wing loading, maximum speed, rate of climb, turn rate, weight and weight distribution, cost and cost distribution. The characteristics of some USSR aircraft are included for comparison. The trends indicate some of the rationale for certain fighter designs and some likely characteristics to be sought in future fighter aircraft designs.

  20. Airbreathing propulsion system trends.

    NASA Technical Reports Server (NTRS)

    Dugan, J. F., Jr.

    1971-01-01

    Among trends in airbreathing propulsion, the priority is shown to belong to the goal of quieting engines to a level no greater than the natural background noise level of the environment in which they operate. For military engines, not so severely noise-constrained, the possibility of stoichiometric gas-turbine engines is shown to be within reach. Very high bypass ratio propfans are especially suitable for V/STOL aircraft. Evolution of reliable variable-geometry inlets and exhaust nozzles characterizes trends in the supersonic regime.

  1. Historical trend in river ice thickness and coherence in hydroclimatological trends in Maine

    USGS Publications Warehouse

    Huntington, T.G.; Hodgkins, G.A.; Dudley, R.W.

    2003-01-01

    We analyzed long-term records of ice thickness on the Piscataquis River in central Maine and air temperature in Maine to determine whether there were temporal trends that were associated with climate warming. The trend in ice thickness was compared and correlated with regional time series of winter air temperature, heating degree days (HDD), date of river ice-out, seasonal center-of-volume date (SCVD) (date on which half of the stream runoff volume during the period 1 Jan. to 31 May has occurred), water temperature, and lake ice-out date. All of these variables except lake ice-out date showed significant temporal trends during the 20th century. Average ice thickness around 28 February decreased by about 23 cm from 1912 to 2001. Over the period 1900 to 1999, winter air temperature increased by 1.7??C and HDD decreased by about 7.5%. Final ice-out date on the Piscataquis River occurred earlier (advanced), by 0.21 days yr-1 over the period 1931 to 2002, and the SCVD advanced by 0.11 days yr-1 over the period 1903 to 2001. Ice thickness was significantly correlated (P-value < 0.01) with winter air temperature, HDD, river ice-out, and SCVD. These systematic temporal trends in multiple hydrologic indicator variables indicate a coherent response to climate forcing.

  2. Linear vs. Non-Linear Earthquake Location and Seismogenic Fault Detection in the Southern Tyrrhenian Sea, Italy

    NASA Astrophysics Data System (ADS)

    Presti, D.; Orecchio, B.; Falcone, G.; Neri, G.

    2006-12-01

    We report a comparison between the performances of linearized and non-linear hypocenter location algorithms working in 3D velocity structures. For this purpose, we used the SIMUL linearized location method by Evans et al. (1994) and the BAYLOC non-linear grid-search probabilistic algorithm by Presti et al. (2004). Comparisons are made using the datasets of P and S readings relative to the two main seismic sequences occurring in the last ten years in the southern Tyrrhenian sea, i.e. the 1998 sequence of maximum magnitude 5.2 near Ustica island and the 2002 sequence of max. magnitude 5.9 offshore Palermo city. We find that in the relatively poor network conditions of both sequences the SIMUL and BAYLOC algorithms produce hypocenter locations of comparable accuracy, while location error estimates from SIMUL are generally less accurate than BAYLOC's. This result is a confirmation in a 3D velocity structure of a finding already reported by previous investigators who compared the performances of linear vs. non-linear location algorithms in 1D structures (Lomax et al., 1998; Lomax et al., 2000; Lippitsch et al., 2005) and further underlines the implications of the linearization process. Also, referring to the problem of detecting seismogenic faults from hypocenter trends delineated in poor network conditions, we introduced a procedure based on BAYLOC's location probability concept with the purpose of establishing when hypocenter trends really mark seismogenic structures and when they simply reflect ill-conditionning of the location process. This procedure (ISO-TEST) showed that while the NE-SW trend of the 2002 sequence can only in minor part be ascribed to ill-conditioning of the location process (what basically means that it effectively marks the orientation of the source), the NW-SE trend of the 1998 sequence is strongly contamined by the location process and source detection is therefore doubtful in this case. Although ISO-TEST is shown to be already capable to bring benefits to seismogenic fault detection in areas where the location problem ill-conditionned, improvements can be expected from wider testing of synthetic earthquake generators and deeper evaluation of misfits between synthetic and real location probability distributions in the space domain. Efforts are currently made in this connection. References Evans, J. R., Eberhart-Phillips, D. & Thurber, C. H., 1994. User's manual for simulps12 for imaging Vp and Vp/Vs: a derivative of the "Thurber" tomographic inversion simul3 for local earthquakes and explosions, U.S. Geol. Surv. Open-file Rept., 94-431. Lippitsch, R., White, R., & Soosalu, H. 2005. Precise hypocentre relocation of microearthquakes in a high- temperature geothermal field: the Torfajökull central volcano, Iceland, Geophysical Journal International 160 - 371-388. Lomax, A., Cattaneo, M., Bethoux, N., Deschamps, A., Courboulex, F., Deverchère, J., & Virieux, J., 1998. Comparison of linear and non-linear earthquake locations for the 1995 Ventimiglia sequence, Poster presentation at: European Geophysical Society, XXII General Assembly, http://alomax.free.fr/posters/vintimiglia. Lomax A., Virieux, J., Volant, P., & Berge-Thierry C., 2000. Probabilistic earthquake location in 3D and layered model, in Advances in Seismic Event Location, 101-134, Kluwer Academic Publishers, Netherlands. Presti, D., Troise, C. & De Natale G., 2004. Probabilistic location of seismic sequences in heterogeneous media, Bull. Seism. Soc. Am., 94, 6, 2239 2253.

  3. TRENDS: Compendium of Benchmark Objects

    NASA Astrophysics Data System (ADS)

    Gonzales, Erica J.; Crepp, Justin R.; Bechter, Eric; Johnson, John A.; Montet, Benjamin T.; Howard, Andrew; Marcy, Geoffrey W.; Isaacson, Howard T.

    2016-01-01

    The physical properties of faint stellar and substellar objects are highly uncertain. For example, the masses of brown dwarfs are usually inferred using theoretical models, which are age dependent and have yet to be properly tested. With the goal of identifying new benchmark objects through observations with NIRC2 at Keck, we have carried out a comprehensive adaptive-optics survey as part of the TRENDS (TaRgetting bENchmark-objects with Doppler Spectroscopy) high-contrast imaging program. TRENDS targets nearby (d < 100 pc), Sun-like stars showing long-term radial velocity accelerations. We present the discovery of 28 confirmed, co-moving companions as well as 19 strong candidate companions to F-, G-, and K-stars with well-determined parallaxes and metallicities. Benchmark objects of this nature lend themselves to a three dimensional orbit determination that will ultimately yield a precise dynamical mass. Unambiguous mass measurements of very low mass companions, which straddle the hydrogen-burning boundary, will allow our compendium of objects to serve as excellent testbeds to substantiate theoretical evolutionary and atmospheric models in regimes where they currently breakdown (low temperature, low mass, and old age).

  4. Meaningful Trends in Wave Activity

    NASA Astrophysics Data System (ADS)

    Solomon, A.; Nakamura, N.

    2010-12-01

    A poleward shift of the mid-latitude eddy driven jet would have major implications for the future distribution of rainfall, surface air temperatures and wind resources. To properly assess such a trend, changes in the wave mean-flow interactions, which maintain the jet must be quantified. This research introduces a new measure of wave activity, amenable to gridded data sets, which is better suited for detecting long-term trends in the influence of atmospheric waves than conventional methods. Based on Kelvin’s circulation, calculated in quasi-conservative, equivalent latitude coordinates, this new measure filters out the reversible, advective flux of wave action, providing a clearer picture of the changes due to non-conservative forces. A theoretical relation between this new finite amplitude wave activity diagnostic and the generalized lagrangian mean pseudomomentum will be presented. Along with a geometrical connection to impulse-Casimir methods, which will help to relate this new measure with more familiar quantities. The results of a numerical comparison between these various metrics for wave activity will be shown from a simple jet forcing experiment. This barotropic simulation demonstrates that conventional diagnostics cannot capture the spatial and temporal distribution of finite amplitude wave forcing as well as this new method. A comparison of wave activity derived from a climate model and the ERA40 reanalysis will provide a new picture of wave forcing and atmospheric circulation.

  5. Trends & Indicators: Enrollment Period

    ERIC Educational Resources Information Center

    Harney, John O.

    2011-01-01

    Since New England Board of Higher Education (NEBHE) began publishing tables and charts exploring "Trends & Indicators" in New England higher education more than a half-century ago, few figures have grabbed as much attention as college "enrollment" data. These local, state, regional and national data go beyond simple headcounts of students going to…

  6. INTERNATIONAL LEGISLATIVE TRENDS

    EPA Science Inventory

    This paper will attempt to provide a pollution prevention legislative overview of where we have been, where we are, and some thoughts on pollution prevention legislative trends for the future. overnments have an important role to play by setting the regulatory framework, but clea...

  7. Evaluation of Project Trend.

    ERIC Educational Resources Information Center

    Unco, Inc., Washington, DC.

    This report is a descriptive evaluation of the five pilot sites of Project TREND (Targeting Resources on the Educational Needs of the Disadvantaged). The five Local Education Agency (LEA) pilot sites are the educational systems of: (1) Akron, Ohio; (2) El Paso, Texas; (3) Newark, New Jersey; (4) Portland, Oregon; and, (5) San Jose (Unified),…

  8. Five Trends for Schools

    ERIC Educational Resources Information Center

    Lapkoff, Shelley; Li, Rose Maria

    2007-01-01

    The authors look at important demographic trends that will have an effect on schools, including roller-coaster enrollments and increasing diversity. For example, compared with 10 years ago, the average child entering a U.S. school today is less likely to live in a family with two married parents but is more likely to have a living grandparent,…

  9. Ten Top Tech Trends

    ERIC Educational Resources Information Center

    McLester, Susan

    2008-01-01

    In this article, the author discusses the major technical issues, products, and practices of the day. The top ten tech trends are listed and discussed. These include: (1) data mining; (2) cyberbullying; (3) 21st century skills; (4) digital content; (5) learning at leisure; (6) personal responders; (7) mobile tools; (8) bandwidth; (9) open-source…

  10. Population Trends and Prospects.

    ERIC Educational Resources Information Center

    Mauldin, W. Parker

    1980-01-01

    Future trends in population are described as they relate to developed and developing nations. It is suggested that for the next 20 years there will be a decrease in population growth rates for all areas of the world except Africa. (Author/SA)

  11. Trends and Issues.

    ERIC Educational Resources Information Center

    Orey, Michael; Sullivan, Michael; Molenda, Michael; Foley, Anne L.; Morgan, Janet; McKenney, Susan; Harada, Violet H.; Lee, Jung

    2003-01-01

    Contains five articles covering general trends and issues in instructional technology, including: developments in corporate training, higher education, and K-12 education; women's contributions to the leading instructional technology journals; developing science education materials via computer-based support; learning in the Information Age; and…

  12. Trends in Interior Environments.

    ERIC Educational Resources Information Center

    Hovey, Robyn

    2000-01-01

    Examines how an understanding of interior design trends can help planners address their present and future furniture needs. Examines how new types of construction and their associated concerns are requiring new approaches from the facility designers and manufacturers of product solutions. (GR)

  13. Trends in Therapeutic Recreation.

    ERIC Educational Resources Information Center

    Smith, Ralph W.

    1995-01-01

    Discusses the implications of the rapid, dramatic changes taking place in therapeutic recreation for individuals with physical disabilities. The article notes the impact of changes in managed care, examines programming trends in therapeutic recreation (adventure/outdoor education, competitive sports, handcycling, health enhancement activities, and…

  14. Decline in snowfall in response to temperature in Satluj basin, western Himalaya

    NASA Astrophysics Data System (ADS)

    Mir, Riyaz Ahmad; Jain, Sanjay K.; Saraf, Arun K.; Goswami, Ajanta

    2015-03-01

    Snow is an essential resource present in the Himalaya. Therefore, monitoring of the snowfall changes over a time period is important for hydrological and climatological purposes. In this study, variability of snowfall from 1976-2008 were analysed and compared with variability in temperature (T max and T min) from 1984-2008 using simple linear regression analysis and Mann-Kendall test in the Satluj Basin. The annual, seasonal, and monthly analyses of average values of snowfall and temperature (T max and T min) have been carried out. The study also consists an analysis of average values of annual snowfall and temperature over six elevation zones (<1500 to >4000 m amsl). During the study, it was observed that the snowfall exhibited declining trends in the basin. The snowfall trends are more sensitive to the climate change below an elevation of 4000 m amsl. Over the elevation zones of 3000-3500 and 4000-4500 m amsl, positive trends of mean annual values of snowfall were observed that may be due to higher precipitation as snowfall at these higher elevations. Although, both negative and positive snowfall trends were statistically insignificant, however, if this decreasing trend in snowfall continues, it may result in significant however, changes in future. Furthermore, the T min is also increasing with statistically significant positive trend at 95% confidence level for November, winter season, annually as well as for the elevation zones of 2500-3000, 3000-3500, and 3500-4000 m amsl. There are dominantly increasing trends in T max with negative trends for February, June-September, monsoon season, and for elevation zone <1500 m amls. It is important to state that in the present basin, during the months of winter season, most of the precipitation is produced as snowfall by the westerly weather disturbances. Thus, the declining nature in snowfall is concurrent with the positive trends in temperature particularly T min, therefore, reflecting that the positive trends in T min may be the dominant factor besides T max in controlling the snowfall trends. The snowfall data were also compared with SCA and this showed a highly positive correlation of 0.95% which validates the utilisation of time series of snowfall for the trend analysis.

  15. Spacecraft-borne long life cryogenic refrigeration: Status and trends

    NASA Technical Reports Server (NTRS)

    Johnson, A. L.

    1983-01-01

    The status of cryogenic refrigerator development intended for, or possibly applicable to, long life spacecraft-borne application is reviewed. Based on these efforts, the general development trends are identified. Using currently projected technology needs, the various trends are compared and evaluated. The linear drive, non-contacting bearing Stirling cycle refrigerator concept appears to be the best current approach that will meet the technology projection requirements for spacecraft-borne cryogenic refrigerators. However, a multiply redundant set of lightweight, moderate life, moderate reliability Stirling cycle cryogenic refrigerators using high-speed linear drive and sliding contact bearings may possibly suffice.

  16. Contrasting temporal trend discovery for large healthcare databases.

    PubMed

    Hrovat, Goran; Stiglic, Gregor; Kokol, Peter; Ojsteršek, Milan

    2014-01-01

    With the increased acceptance of electronic health records, we can observe the increasing interest in the application of data mining approaches within this field. This study introduces a novel approach for exploring and comparing temporal trends within different in-patient subgroups, which is based on associated rule mining using Apriori algorithm and linear model-based recursive partitioning. The Nationwide Inpatient Sample (NIS), Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality was used to evaluate the proposed approach. This study presents a novel approach where visual analytics on big data is used for trend discovery in form of a regression tree with scatter plots in the leaves of the tree. The trend lines are used for directly comparing linear trends within a specified time frame. Our results demonstrate the existence of opposite trends in relation to age and sex based subgroups that would be impossible to discover using traditional trend-tracking techniques. Such an approach can be employed regarding decision support applications for policy makers when organizing campaigns or by hospital management for observing trends that cannot be directly discovered using traditional analytical techniques. PMID:24120407

  17. Using optoacoustic imaging for measuring the temperature dependence of Grüneisen parameter in optically absorbing solutions

    PubMed Central

    Petrova, Elena; Ermilov, Sergey; Su, Richard; Nadvoretskiy, Vyacheslav; Conjusteau, André; Oraevsky, Alexander

    2013-01-01

    Grüneisen parameter is a key temperature-dependent physical characteristic responsible for thermoelastic efficiency of materials. We propose a new methodology for accurate measurements of temperature dependence of Grüneisen parameter in optically absorbing solutions. We use two-dimensional optoacoustic (OA) imaging to improve accuracy of measurements. Our approach eliminates contribution of local optical fluence and absorbance. To validate the proposed methodology, we studied temperature dependence of aqueous cupric sulfate solutions in the range from 22 to 4°C. Our results for the most diluted salt perfectly matched known temperature dependence for the Grüneisen parameter of water. We also found that Grüneisen-temperature relationship for cupric sulfate exhibits linear trend with respect to the concentration. In addition to accurate measurements of Grüneisen changes with temperature, the developed technique provides a basis for future high precision OA temperature monitoring in live tissues. PMID:24150350

  18. Spatial and temporal variation of rainfall trends of Sri Lanka

    NASA Astrophysics Data System (ADS)

    Wickramagamage, P.

    2015-06-01

    This study was based on daily rainfall data of 48 stations distributed over the entire island covering a 30-year period from 1981 to 2010. Data analysis was done to identify the spatial pattern of rainfall trends. The methods employed in data analysis are linear regression and interpolation by Universal Kriging and Radial Basis function. The slope of linear regression curves of 48 stations was used in interpolation. The regression coefficients show spatially and seasonally variable positive and negative trends of annual and seasonal rainfall. About half of the mean annual pentad series show negative trends, while the rest shows positive trends. By contrast, the rainfall trends of the Southwest Monsoon (SWM) season are predominantly negative throughout the country. The first phase of the Northeast Monsoon (NEM1) displays downward trends everywhere, with the exception of the Southeastern coastal area. The strongest negative trends were found in the Northeast and in the Central Highlands. The second phase (NEM2) is mostly positive, except in the Northeast. The Inter-Monsoon (IM) periods have predominantly upward trends almost everywhere, but still the trends in some parts of the Highlands and Northeast are negative. The long-term data at Watawala Nuwara Eliya and Sandringham show a consistent decline in the rainfall over the last 100 years, particularly during the SWM. There seems to be a faster decline in the rainfall in the last 3 decades. These trends are consistent with the observations in India. It is generally accepted that there has been changes in the circulation pattern. Weakening of the SWM circulation parameters caused by global warming appears to be the main causes of recent changes. Effect of the Asian Brown Cloud may also play a role in these changes.

  19. Upper-Stratospheric Ozone Trends 1979-1998

    NASA Technical Reports Server (NTRS)

    Newchurch, M. J.; Cunnold, Derek; Bishop, Lane; Flynn, Lawrence E.; Godin, Sophie; Frith, Stacey Hollandsworth; Hood, Lon; Miller, Alvin J.; Oltmans, Sam; Randel, William

    2002-01-01

    Extensive analyses of ozone observations between 1978 and 1998 measured by Dobson Umkehr, Stratospheric Aerosol and Gas Experiment (SAGE) I and II, and Solar Backscattered Ultraviolet (SBUV) and (SBUV)/2 indicate continued significant ozone decline throughout the extratropical upper stratosphere from 30-45 km altitude. The maximum annual linear decline of -0.8 +/- 0.2 %/yr(2sigma) occurs at 40 km and is well described in terms of a linear decline modulated by the 11-year solar variation. The minimum decline of -0.110.1% yr-1(2o) occurs at 25 km in midlatitudes, with remarkable symmetry between the Northern and Southern Hemispheres at 40 km altitude. Midlatitude upper-stratospheric zonal trends exhibit significant seasonal variation (+/- 30% in the Northern Hemisphere, +/- 40% in the Southern Hemisphere) with the most negative trends of -1.2%/yr occurring in the winter. Significant seasonal trends of -0.7 to -0.9%/yr occur at 40 km in the tropics between April and September. Subjecting the statistical models used to calculate the ozone trends to intercomparison tests on a variety of common data sets yields results that indicate the standard deviation between trends estimated by 10 different statistical models is less than 0.1%/yr in the annual-mean trend for SAGE data and less than 0.2%/yr in the most demanding conditions (seasons with irregular, sparse data) [World Meteorological Organization (WMO), 1998]. These consistent trend results between statistical models together with extensive consistency between the independent measurement-system trend observations by Dobson Umkehr, SAGE I and II, and SBUV and SBUV/2 provide a high degree of confidence in the accuracy of the declining ozone amounts reported here. Additional details of ozone trend results from 1978 to 1996 (2 years shorter than reported here) along with lower-stratospheric and tropospheric ozone trends, extensive intercomparisons to assess relative instrument drifts, and retrieval algorithm details are given by WMO [1998].

  20. Ozone trends and their relationship to characteristic weather patterns.

    PubMed

    Austin, Elena; Zanobetti, Antonella; Coull, Brent; Schwartz, Joel; Gold, Diane R; Koutrakis, Petros

    2015-09-01

    Local trends in ozone concentration may differ by meteorological conditions. Furthermore, the trends occurring at the extremes of the Ozone distribution are often not reported even though these may be very different than the trend observed at the mean or median and they may be more relevant to health outcomes. Classify days of observation over a 16-year period into broad categories that capture salient daily local weather characteristics. Determine the rate of change in mean and median O3 concentrations within these different categories to assess how concentration trends are impacted by daily weather. Further examine if trends vary for observations in the extremes of the O3 distribution. We used k-means clustering to categorize days of observation based on the maximum daily temperature, standard deviation of daily temperature, mean daily ground level wind speed, mean daily water vapor pressure and mean daily sea-level barometric pressure. The five cluster solution was determined to be the appropriate one based on cluster diagnostics and cluster interpretability. Trends in cluster frequency and pollution trends within clusters were modeled using Poisson regression with penalized splines as well as quantile regression. There were five characteristic groupings identified. The frequency of days with large standard deviations in hourly temperature decreased over the observation period, whereas the frequency of warmer days with smaller deviations in temperature increased. O3 trends were significantly different within the different weather groupings. Furthermore, the rate of O3 change for the 95th percentile and 5th percentile was significantly different than the rate of change of the median for several of the weather categories.We found that O3 trends vary between different characteristic local weather patterns. O3 trends were significantly different between the different weather groupings suggesting an important interaction between changes in prevailing weather conditions and O3 concentration. PMID:25004934

  1. Optimal Linear Glauber Model

    NASA Astrophysics Data System (ADS)

    Sahoo, Shaon; Ganguly, Soumya Kanti

    2015-04-01

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

  2. Trends in motor gasolines: 1942-1981

    SciTech Connect

    Shelton, E M; Whisman, M L; Woodward, P W

    1982-06-01

    Trends in motor gasolines for the years of 1942 through 1981 have been evaluated based upon data contained in surveys that have been prepared and published by the Bartlesville Energy Technology Center (BETC). These surveys have been published twice annually since 1935 describing the properties of motor gasolines from throughout the country. The surveys have been conducted in cooperation with the American Petroleum Institute (API) since 1948. Various companies from throughout the country obtain samples from retail outlets, analyze the samples by the American Society for Testing and Materials (ASTM) procedures, and report data to the Bartlesville center for compilation, tabulation, calculation, analysis and publication. A typical motor gasoline report covers 2400 samples from service stations throughout the country representing some 48 companies that manufacture and supply gasoline. The reports include trend charts, octane plots, and tables of test results from about a dozen different tests. From these data in 77 semiannual surveys, a summary report has thus been assembled that shows trends in motor gasolines throughout the entire era of winter 1942 to 1943 to the present. Trends of physical properties including octane numbers, antiknock ratings, distillation temperatures, Reid vapor pressure, sulfur and lead content are tabulated, plotted and discussed in the current report. Also included are trend effects of technological advances and the interactions of engine design, societal and political events and prices upon motor gasoline evolution during the 40 year period.

  3. Rethinking the longitudinal stream temperature paradigm: region-wide comparison of thermal infrared imagery reveals unexpected complexity of river temperatures

    USGS Publications Warehouse

    Fullerton, Aimee H.; Torgersen, Christian; Lawler, Joshua J.; Faux, Russell N.; Steel, E. Ashley; Beechie, Timothy J.; Ebersole, Joseph L.; Leibowitz, Scott J.

    2015-01-01

    Prevailing theory suggests that stream temperature warms asymptotically in a downstream direction, beginning at the temperature of the source in the headwaters and leveling off downstream as it converges to match meteorological conditions. However, there have been few empirical examples of longitudinal patterns of temperature in large rivers due to a paucity of data. We constructed longitudinal thermal profiles (temperature versus distance) for 53 rivers in the Pacific Northwest (USA) using an extensive dataset of remotely sensed summertime river temperatures and classified each profile into one of five patterns of downstream warming: asymptotic (increasing then flattening), linear (increasing steadily), uniform (not changing), parabolic (increasing then decreasing), or complex (not fitting other classes). We evaluated (1) how frequently profiles warmed asymptotically downstream as expected, and (2) whether relationships between river temperature and common hydroclimatic variables differed by profile class. We found considerable diversity in profile shape, with 47% of rivers warming asymptotically, and 53% having alternative profile shapes. Water temperature did not warm substantially over the course of the river for coastal parabolic and uniform profiles, and for some linear and complex profiles. Profile classes showed no clear geographical trends. The degree of correlation between river temperature and hydroclimatic variables differed among profile classes, but there was overlap among classes. Water temperature in rivers with asymptotic or parabolic profiles was positively correlated with August air temperature, tributary temperature and velocity, and negatively correlated with elevation, August precipitation, gradient, and distance upstream. Conversely, associations were less apparent in rivers with linear, uniform, or complex profiles. Factors contributing to the unique shape of parabolic profiles differed for coastal and inland rivers, where downstream cooling was influenced locally by climate or cool water inputs, respectively. Potential drivers of shape for complex profiles were specific to each river. These thermal patterns indicate diverse thermal habitats that may promote resilience of aquatic biota to climate change. Without this spatial context, climate change models may incorrectly estimate loss of thermally suitable habitat.

  4. The recent warming trend in North Greenland

    NASA Astrophysics Data System (ADS)

    Orsi, Anais; Kawamura, Kenji; Masson-Delmotte, Valerie; Landais, Amaelle; Severinghaus, Jeff

    2015-04-01

    The arctic is the fastest warming region on Earth, but it is also one where there is little historical data. Although summer warming causes melt, the annual temperature trend is dominated by the winter and fall season, which are much less well documented. In addition, the instrumental record relies principally on coastal weather stations, and there are very few direct temperature observations in the interior dating back more than 30 years, especially in North Greenland, where the current warming trend is the largest. Here, we present a temperature reconstruction from NEEM (51°W, 77°N), in North Greenland, for the last 100 years, which allows us to put the recent trend in the context of the longer term climate. We use a combination of two independent proxies to reconstruct the temperature history at NEEM: borehole temperature and inert gas isotope measurements in the firn. Borehole temperature takes advantage of the low temperature diffusivity of the snow and ice, which allows the temperature history to be preserved in the ice for several centuries. Temperature gradients in the firn (old snow above the ice) influence the gas isotopic composition: thermal fractionation causes heavy isotopes to concentrate on the cold end of the firn column. We measured the isotopes of inert gases (N2, Ar and Kr), which have a constant atmospheric composition through time, and use the thermal fractionation signal as an additional constraint on the temperature history at the site. We find that NEEM has been warming by 0.86±0.22°C/decade over the past 30 years, from -28.55±0.29°C for the 1900-1970 average to -26.77±0.16°C for the 2000-2010 average. The warming rate at NEEM is similar to that of Greenland Summit, and confirms the large warming trends in North Greenland (polar amplification) and high altitude sites (tropospheric rather than surface warming). Water isotopes show that the recent past has not met the level of the 1928 anomaly; but the average of the past 30 years has the highest isotope values since 1724, which suggests that the sustained warming of the past 30 years is indeed exceptional.

  5. Reconciliation of global temperatures

    NASA Astrophysics Data System (ADS)

    Benestad, R. E.

    2012-03-01

    In recent years there has been a public debate about whether the rate of global warming has waned, prompting the paper 'Is the climate warming or cooling?' in Geophysical Research Letters by Easterling and Wehner (2009). This question has also attracted attention in wider scientific circles, and in a recent paper in Science, Solomon et al (2010) suggested that a decrease in stratospheric water vapour concentrations has slowed the global surface temperature rate between 2000 and 2009. Yet another study by Kaufmann et al (2011) argued that the 'hiatus' in the global warming coincided with near constant combined anthropogenic and natural forcings. The reason: a declining solar insolation, a shift to La Niña conditions and a rapid growth in short-lived sulfur emissions have masked the effect from rising greenhouse gas concentrations (GHGs). So, what is new? In the paper 'Global temperature evolution 1979-2010', Foster and Rahmstorf (2011) re-examine the situation. Whereas Kaufmann's group only examined the global temperature record from the Hadley Centre and Climate Research Unit (HadCRUT3; Brohan et al 2006) in the United Kingdom, Foster and Rahmstorf present an analysis of the range of available historical temperature records, both from surface thermometers and satellite-based remote sensing. There is one caveat associated with the analysis that Kaufmann's group carried out, which is that the HadCRUT3 record does not fully capture recent enhanced warming over the Arctic, thereby underestimating the evolution of the true global mean compared with other sources. Other analyses, such as the one from NASA/GISS (GISSTEMP; Hansen et al 2010) and those based on atmospheric models (e.g. Kalnay et al 1996), cover the Arctic region better by interpolating the values surrounding the data void or taking physics into account. These, and independent indices such as sea-ice extent (Kinnard et al 2011), ice melting over Greenland (Mernild et al 2009) and permafrost thawing/warming (Isaksen et al 2007), all point to unusual warm conditions in the Arctic. Foster and Rahmstorf examine global mean temperature trends after accounting for variations associated with three different naturally occurring phenomena: El Niño-Southern Oscillation, volcanic aerosols and solar variability. They used a similar approach to Lean and Rind (2008), but unlike Solomon et al (2010), they did not account for stratospheric water vapour concentrations. Their findings agree with Kaufmann et al (2011) who argue that this factor plays a minor role. Foster and Rahmstorf did not need to account for anthropogenic sulfur aerosols, as a fairly linear warming trend became discernable once the ENSO, solar activity and volcanism were accounted for. There is always a risk that multiple regression analysis may misattribute significance to unrelated factors (Benestad and Schmidt 2009), and Foster and Rahmstorf made some efforts to test whether their results could be affected by such spurious effects, making their results more convincing. Unfortunately, this is not always the case for papers in the scientific literature, and sometimes papers appear in journals even if they cannot be justified on scientific grounds (i.e. Wagner 2011). An interesting aside, however, is that similar physical principles implying a warming resulting from higher CO2 concentrations also are the basis for estimating the temperature from the microwave channels measured by satellite-borne instruments. The fact that Foster and Rahmstorf reconcile the trends seen in the in situ surface and satellite-borne remote sensing data brings out the consistency with the physics believed to be central to global warming. In my view, Foster and Rahmstorf do not come up with new ground-breaking results, but rather a view that fits in with the tacit knowledge about climate. The most interesting aspect is perhaps the different implications for effects associated with stratospheric water vapour and sulfur aerosols. It is also reassuring to see reasonably good agreement between the different data sources, suggesting both r

  6. Trend Mining in Social Networks: From Trend Identification to Visualisation

    E-print Network

    Coenen, Frans

    Science, University of Liverpool, Liverpool, UK (2) Graduate School of Information Sciences, HiroshimaTrend Mining in Social Networks: From Trend Identification to Visualisation Puteri N.E. Nohuddin1 and National Centre for Zoonosis Research, Leahurst, Neston, UK Abstract: A four stage social network trend

  7. Seasonality and trend analysis of tuberculosis in Lahore, Pakistan from 2006 to 2013.

    PubMed

    Khaliq, Aasia; Batool, Syeda Aadila; Chaudhry, M Nawaz

    2015-12-01

    Tuberculosis (TB) is a respiratory infectious disease which shows seasonality. Seasonal variation in TB notifications has been reported in different regions, suggesting that various geographic and demographic factors are involved in seasonality. The study was designed to find out the temporal and seasonal pattern of TB incidence in Lahore, Pakistan from 2006 to 2013 in newly diagnosed pulmonary TB cases. SPSS version 21 software was used for correlation to determine the temporal relationship and time series analysis for seasonal variation. Temperature was found to be significantly associated with TB incidence at the 0.01 level with p=0.006 and r=0.477. Autocorrelation function and partial autocorrelation function showed a significant peak at lag 4 suggesting a seasonal component of the TB series. Seasonal adjusted factor showed peak seasonal variation in the second quarter (April-June). The expert modeler predicted the Holt-Winter's additive model as the best fit model for the time series, which exhibits a linear trend with constant (additive) seasonal variations, and the stationary R(2) value was found to be 0.693. The forecast shows a declining trend with seasonality. A significant temporal relation with a seasonal pattern and declining trend with variable amplitudes of fluctuation was observed in the incidence of TB. PMID:26318884

  8. Trends in surface ozone over Europe, 1978-1990

    NASA Technical Reports Server (NTRS)

    Low, Pak Sum; Kelly, P. Michael; Davies, Trevor D.

    1994-01-01

    It has been suggested that surface ozone concentrations in rural areas of Europe have been increasing at a rate of 1 to 3 percent per year over the past two to three decades, presumably due to human influences (Feister and Warmbt, 1987; Bojkov, 1988; Penkett, 1989). Recently, we have analyzed surface ozone data from 20 European stations of differing character (remote, rural, suburban and urban) for a common period of 1978-1988 (Low et al., 1992). It was found that there were pronounced annual and seasonal variations in the linear trends in different areas, and there was no dominant region-wide trend. In spring and, most notably, summer, stations on the maritime fringe of the network generally exhibited negative trends whilst those located further into the continental interior exhibited positive trends. In winter, most of the stations in the network exhibited positive trends. Relatively few of these trends were statistically significant. This paper updates our earlier analysis by extending the data sets of the network up to the year 1990. The spatial variations in surface ozone trends over the extended period 1978-1990 are examined and discussed in comparison to the 1978-1988 patterns. The update confirms the overall conclusions of the earlier analysis, specifically that caution should be exercised in interpreting the results of trend analyses based on station data representative of a limited period of time and/or geographical area.

  9. A Global Assessment of Long-Term Greening and Browning Trends in Pasture Lands Using the GIMMS LAI3g Dataset

    NASA Technical Reports Server (NTRS)

    Cook, Benjamin I.; Pau, Stephanie

    2013-01-01

    Pasture ecosystems may be particularly vulnerable to land degradation due to the high risk of human disturbance (e.g., overgrazing, burning, etc.), especially when compared with natural ecosystems (non-pasture, non-cultivated) where direct human impacts are minimal. Using maximum annual leaf area index (LAImax) as a proxy for standing biomass and peak annual aboveground productivity, we analyze greening and browning trends in pasture areas from 1982-2008. Inter-annual variability in pasture productivity is strongly controlled by precipitation (positive correlation) and, to a lesser extent, temperature (negative correlation). Linear temporal trends are significant in 23% of pasture cells, with the vast majority of these areas showing positive LAImax trends. Spatially extensive productivity declines are only found in a few regions, most notably central Asia, southwest North America, and southeast Australia. Statistically removing the influence of precipitation reduces LAImax trends by only 13%, suggesting that precipitation trends are only a minor contributor to long-term greening and browning of pasture lands. No significant global relationship was found between LAImax and pasture intensity, although the magnitude of trends did vary between cells classified as natural versus pasture. In the tropics and Southern Hemisphere, the median rate of greening in pasture cells is significantly higher than for cells dominated by natural vegetation. In the Northern Hemisphere extra-tropics, conversely, greening of natural areas is 2-4 times the magnitude of greening in pasture areas. This analysis presents one of the first global assessments of greening and browning trends in global pasture lands, including a comparison with vegetation trends in regions dominated by natural ecosystems. Our results suggest that degradation of pasture lands is not a globally widespread phenomenon and, consistent with much of the terrestrial biosphere, there have been widespread increases in pasture productivity over the last 30 years.

  10. Reassessment of MIPAS age of air trends and variability

    NASA Astrophysics Data System (ADS)

    Haenel, F. J.; Stiller, G. P.; von Clarmann, T.; Funke, B.; Eckert, E.; Glatthor, N.; Grabowski, U.; Kellmann, S.; Kiefer, M.; Linden, A.; Reddmann, T.

    2015-11-01

    A new and improved setup of the SF6 retrieval together with a newly calibrated version of MIPAS-ENVISAT level 1b spectra (version 5, ESA data version 5.02/5.06) was used to obtain a new global SF6 data set, covering the total observational period of MIPAS from July 2002 to April 2012 for the first time. Monthly and zonally averaged SF6 profiles were converted into mean age of air using a tropospheric SF6-reference curve. The obtained data set of age of air was compared to airborne age of air measurements. The temporal evolution of the mean age of air was then investigated in 10° latitude and 1-2 km altitude bins. A regression model consisting of a constant and a linear trend term, two proxies for the quasi-biennial oscillation variation, sinusoidal terms for the seasonal and semiannual variation and overtones was fitted to the age of air time series. The annual cycle for particular regions in the stratosphere was investigated and compared to other studies. The age of air trend over the total MIPAS period consisting of the linear term was assessed and compared to previous findings of Stiller et al. (2012). While the linear increase of mean age is confirmed to be positive for the northern midlatitudes and southern polar middle stratosphere, differences are found in the northern polar upper stratosphere, where the mean age is now found to increase as well. The magnitude of trends in the northern midlatitude middle stratosphere is slightly lower compared to the previous version and the trends fit remarkably well to the trend derived by Engel et al. (2009). Negative age of air trends found by Stiller et al. (2012) are confirmed for the lowermost tropical stratosphere and lowermost southern midlatitudinal stratosphere. Differences to the previous data versions occur in the middle tropical stratosphere around 25 km, where the trends are now negative. Overall, the new latitude-altitude distribution of trends appears to be less patchy and more coherent than the previous one. The new data provide evidence of an accelerating shallow branch of the Brewer-Dobson circulation, at least in the Southern Hemisphere. Finally the age of air decadal trends are compared to trends calculated with simulated SF6 values by the Karlsruhe Simulation Model of the Middle Atmosphere (KASIMA) and good agreement is found. The hemispheric asymmetry in the trends found in the MIPAS data is also indicated in the trends calculated with simulated SF6 values by the KASIMA model.

  11. Linear modulator

    NASA Technical Reports Server (NTRS)

    1972-01-01

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

  12. RECENT TRENDS IN THE FISHERY

    E-print Network

    , are available from 083, Technical Information Division, Environmental Science Information Center, NOAARECENT TRENDS IN THE FISHERY Some of the more important trends in the northern shrimp fishery in the Gulf of Maine pertain to the fleet and to the shrimp catch. In regard to the fleet, the trend is toward

  13. A Climate Trend Analysis of Burkina Faso

    USGS Publications Warehouse

    Funk, Christopher C.; Rowland, Jim; Eilerts, Gary; Adoum, Alkhalil; White, Libby

    2012-01-01

    This brief report, drawing from a multi-year effort by the U.S. Agency for International Development (USAID) Famine Early Warning Systems Network (FEWS NET), examines recent trends in rainfall and air temperatures. These analyses are based on quality controlled station observations. Conclusions: * Summer rains have remained steady over the past 20 years, but remain 15 percent below the 1920-69 average. * Temperatures have increased by 0.6° Celsius since 1975, amplifying the effect of droughts. * The amount of farmland per person is low, and declining. * Burkina Faso has offset rapid population growth with improved yields. * Continued yield growth would maintain current levels of per capita food production.

  14. A climate trend analysis of Mali

    USGS Publications Warehouse

    Funk, Christopher C.; Rowland, Jim; Adoum, Alkhalil; Eilerts, Gary; White, Libby

    2012-01-01

    This brief report, drawing from a multi-year effort by the U.S. Agency for International Development (USAID) Famine Early Warning Systems Network (FEWS NET), identifies modest declines in rainfall, accompanied by increases in air temperatures. These analyses are based on quality-controlled station observations. Conclusions: * Summer rains have remained relatively steady for the past 20 years, but are 12 percent below the 1920-1969 average. * Temperatures have increased by 0.8° Celsius since 1975, amplifying the effect of droughts. * Cereal yields are low but have been improving. * Current population and agricultural trends indicate that increased yields have offset population expansion, keeping per capita cereal production steady.

  15. Synchrony of trend shifts in Sahel summer rainfall and global oceanic evaporation, 1950-2012

    NASA Astrophysics Data System (ADS)

    Diawara, A.; Tachibana, Y.; Oshima, K.; Nishikawa, H.; Ando, Y.

    2015-11-01

    Between 1950 and 2012, summer (rainy season) rainfall in the Sahel changed from a multi-decadal decreasing trend to an increasing trend (positive trend shift) in the mid-1980s. We found that this trend shift was synchronous with similar trend shifts in global oceanic evaporation and in land precipitation in all continents except the Americas. The trend shift in oceanic evaporation occurred mainly in the Southern Hemisphere (SH) and the subtropical oceans of the Northern Hemisphere (NH). Because increased oceanic evaporation strengthens the atmospheric moisture transport toward land areas, the synchrony of oceanic evaporation and land precipitation is reasonable. Surface scalar winds over the SH oceans also displayed a positive trend shift. Sea surface temperature (SST) displayed a trend shift in the mid-1980s that was negative (increasing, then decreasing) in the SH and positive in the NH. Although SST had opposite trend shifts in both hemispheres, the trend shift in evaporation was positive in both hemispheres. We infer that because strong winds promote evaporative cooling, the trend shift in SH winds strengthened the trend shifts of both SST and evaporation in the SH. Because high SST promotes evaporation, the trend shift in NH SST strengthened the NH trend shift in evaporation. Thus differing oceanic roles in the SH and NH generated the positive trend shift in evaporation; however, the details of moisture transport toward the Sahel are still unclear.

  16. Synchronized trend shift of Sahel rainfall with global oceanic evaporation occurred in the mid-1980s

    NASA Astrophysics Data System (ADS)

    Diawara, Alima; Tachibana, Yoshihiro; Oshima, Kazuhiro; Nishikawa, Hatsumi; Ando, Yuta

    2015-04-01

    Trend shift of Sahel rainfall from decrease to increase occurred in the mid-1980s. This trend shift and its relation to global oceans were investigated by data analyses. We discovered that the Sahel trend shift was synchronized with the trend shift of global oceanic evaporation, with time series like a '' shape, i.e., from decrease to increase. Land precipitation also tended to have the '' shaped trend shift except America continents. The trend shift of the oceanic evaporation was mainly in the Southern Hemisphere (SH), extending to the subtropical Northern Hemisphere (NH) including the Pacific, Atlantic, and Indian Ocean. Because the increase of oceanic evaporation strengthens atmospheric moisture transport toward the land, the synchronized trend shifts of the oceanic evaporation with the land precipitation is reasonable. Surface scalar winds over the oceans in the SH had the '' shaped trend shift. Sea surface temperature (SST) also had the trend shifts in the mid-1980s: a '/\\' shaped in SH, while '' shaped in the NH. In spite of the opposite SST trend shift of the NH to the SH, the evaporation trend shift was in the '' shape in the both hemispheres. Since strong wind promotes evaporation cooling of the SST, the SH wind trend shift strengthened the trend shifts of both SSTs and the evaporation. Because high SST anomalies promote the evaporation, the NH SST trend shift strengthened the evaporation trend shift.

  17. Trends in PET imaging

    SciTech Connect

    Moses, William W.

    2000-11-01

    Positron Emission Tomography (PET) imaging is a well established method for obtaining information on the status of certain organs within the human body or in animals. This paper presents an overview of recent trends PET instrumentation. Significant effort is being expended to develop new PET detector modules, especially those capable of measuring depth of interaction. This is aided by recent advances in scintillator and pixellated photodetector technology. The other significant area of effort is development of special purpose PET cameras (such as for imaging breast cancer or small animals) or cameras that have the ability to image in more than one modality (such as PET / SPECT or PET / X-Ray CT).

  18. Petrography and Stable Isotopic Trend Associated with Mammoth Hotspring Travertine, Yellowstone National Park, Wyoming

    NASA Technical Reports Server (NTRS)

    Guidry, S. A.; Chafetz, H. S.

    2002-01-01

    Active Yellowstone travertines and relict travertines from successively older deposits exhibit a strong linear trend in stable isotopic values indicative of geochemical evolution throughout the course of hotspring activity. Additional information is contained in the original extended abstract.

  19. A microcomputer-controlled linear heater

    SciTech Connect

    Schuck, V.; Rahimi, S. )

    1991-10-01

    In this note the circuits and principles of operation of a relatively simple and inexpensive linear temperature ramp generator are described. The upper-temperature limit and the heating rate are controlled by an Apple II microcomputer. The temperature versus time is displayed on the screen and may be plotted by an {ital x}-{ital y} plotter.

  20. Recent trends in aerosol optical properties derived from AERONET measurements

    NASA Astrophysics Data System (ADS)

    Li, J.; Carlson, B. E.; Dubovik, O.; Lacis, A. A.

    2014-06-01

    The Aerosol Robotic Network (AERONET) has been providing high-quality retrievals of aerosol optical properties from the surface at worldwide locations for more than a decade. Many sites have continuous and consistent records for more than 10 years, which enables the investigation of long-term trends of aerosol properties at these locations. In this study, we present trend analysis of AERONET data at 63 selected locations. In addition to commonly studied parameters such as Aerosol Optical Depth (AOD) and Ångström Exponent (AE), we also focus on Absorption Aerosol Optical Depth (ABS), Scattering Optical Depth (SCT), Single Scattering Albedo (SSA) and the Absorption Ångström Exponent (AAE). Two statistical methods are used to detect and estimate the trend: Mann-Kendall test associated with Sen's slope and linear least square fitting. Their results agree well in terms of the significance of the trend for the majority of the cases. The results indicate that Europe and North America experienced a uniform decrease in AOD and SCT, while significant (> 90%) increases of these two parameters are found for Kanpur, India. Most of European and North American sites also show negative trends for ABS, as well as three East Asian stations. The reduction in ABS results in positive SSA trends for these locations. The increase of SCT also leads to a positive SSA trend for Kanpur. Negative SSA trends are mostly found over South America, Australia and a few West European stations, which are mainly attributed to the increase of absorption. Fewer stations are found with significant trends for AE and AAE. In general, the trends do not exhibit obvious seasonality for the majority of the parameters and stations.

  1. The Developmental Trends in Metaphoric Production: The Roles of Knowing-Level and Vocabulary Capacity.

    ERIC Educational Resources Information Center

    Wu, Pichun

    This proposed study will examine the underlying causalities of the U-shaped developmental trend in metaphoric production and the causes which make up the linearly increasing trend. Seven hypotheses will be tested in the study. Ninety children, all from middle-class families and attending nursery and public schools in Austin (Texas), with ages…

  2. Southern African Ozone Trends (1990-2007): Influences of Climate Variability and Anthropogenic Sources

    NASA Astrophysics Data System (ADS)

    Thompson, A. M.; Balashov, N. V.; Witte, J. C.; Piketh, S.; Coetzee, G. J.; Thouret, V.

    2014-12-01

    Studies of tropospheric ozone trends over the southern African Highveld in the 1990-2007 period present a paradox. We used monthly averaged surface ozone data from 5 South African monitoring stations east of Johannesburg in a linear regression model to show that the cycles associated with the El Niño/La Niña make a considerable contribution to interannual ozone variability through perturbations in cloud cover, temperature and precipitation that interact with photochemistry (see Figure). During El Niño periods, typically sunnier and drier, summertime ozone is enhanced, whereas wetter, cloudier conditions of a La Niña are associated with lower ozone. Interestingly, the 5 stations show very little evidence of a statistically significant trend from 1990 through 2007. Over the same time period, the regression model shows that free tropospheric ozone, from 5-11 km, taken from monthly averaged SHADOZ (Southern Hemisphere ADditional OZonesondes) and MOZAIC (Measurement of Ozone and Water Vapour on Airbus in-service Aircraft) profiles, increased significantly (+20-25%/decade) in late autumn and early winter (May-July). There is also a positive ozone trend near the tropopause in summer (Nov.-Dec.) but none during the oft-studied months of biomass fires (Sept.-Oct.). It is difficult to interpret the seemingly contradictory trends in terms of emissions of ozone precursors that are not well characterized over the Highveld and larger southern African region. However, we ran a series of back-trajectories at 500 and 300 hPa to coincide with the profile sampling times in May-August 1990-2007. Regional contributions are implicated by recirculation in the Johannesburg region. Trajectories also point to long-range transport from the greater African continent, south Atlantic and South America, all known regions of high ozone and in the case of South America, growing pollution from emerging mega-cities.

  3. Optimal allocation of trend following strategies

    NASA Astrophysics Data System (ADS)

    Grebenkov, Denis S.; Serror, Jeremy

    2015-09-01

    We consider a portfolio allocation problem for trend following (TF) strategies on multiple correlated assets. Under simplifying assumptions of a Gaussian market and linear TF strategies, we derive analytical formulas for the mean and variance of the portfolio return. We construct then the optimal portfolio that maximizes risk-adjusted return by accounting for inter-asset correlations. The dynamic allocation problem for n assets is shown to be equivalent to the classical static allocation problem for n2 virtual assets that include lead-lag corrections in positions of TF strategies. The respective roles of asset auto-correlations and inter-asset correlations are investigated in depth for the two-asset case and a sector model. In contrast to the principle of diversification suggesting to treat uncorrelated assets, we show that inter-asset correlations allow one to estimate apparent trends more reliably and to adjust the TF positions more efficiently. If properly accounted for, inter-asset correlations are not deteriorative but beneficial for portfolio management that can open new profit opportunities for trend followers. These concepts are illustrated using daily returns of three highly correlated futures markets: the E-mini S&P 500, Euro Stoxx 50 index, and the US 10-year T-note futures.

  4. Atmospheric changes through 2012 as shown by iteratively homogenized radiosonde temperature and wind data (IUKv2)

    NASA Astrophysics Data System (ADS)

    Sherwood, Steven C.; Nishant, Nidhi

    2015-05-01

    We present an updated version of the radiosonde dataset homogenized by Iterative Universal Kriging (IUKv2), now extended through February 2013, following the method used in the original version (Sherwood et al 2008 Robust tropospheric warming revealed by iteratively homogenized radiosonde data J. Clim. 21 5336-52). This method, in effect, performs a multiple linear regression of the data onto a structural model that includes both natural variability, trends, and time-changing instrument biases, thereby avoiding estimation biases inherent in traditional homogenization methods. One modification now enables homogenized winds to be provided for the first time. This, and several other small modifications made to the original method sometimes affect results at individual stations, but do not strongly affect broad-scale temperature trends. Temperature trends in the updated data show three noteworthy features. First, tropical warming is equally strong over both the 1959-2012 and 1979-2012 periods, increasing smoothly and almost moist-adiabatically from the surface (where it is roughly 0.14 K/decade) to 300 hPa (where it is about 0.25 K/decade over both periods), a pattern very close to that in climate model predictions. This contradicts suggestions that atmospheric warming has slowed in recent decades or that it has not kept up with that at the surface. Second, as shown in previous studies, tropospheric warming does not reach quite as high in the tropics and subtropics as predicted in typical models. Third, cooling has slackened in the stratosphere such that linear trends since 1979 are about half as strong as reported earlier for shorter periods. Wind trends over the period 1979-2012 confirm a strengthening, lifting and poleward shift of both subtropical westerly jets; the Northern one shows more displacement and the southern more intensification, but these details appear sensitive to the time period analysed. There is also a trend toward more easterly winds in the middle and upper troposphere of the deep tropics.

  5. Global change integrating factors: Tropical tropopause trends

    SciTech Connect

    Reck, R.A.

    1994-10-01

    This research proposes new criteria, shifts in the height and temperature of the tropical tropopause, as measures of global climate change. The search for signs of global warming in the temperature signal near the earth`s surface is extremely difficult, largely because numerous factors contribute to surface temperature forcing with only a small signal-to-noise ratio relative to long-term effects. In the long term, no part of the atmosphere can be considered individually because the evolution will be a function of all states of all portions. A large surface greenhouse signal might ultimately be expected, but the analysis of surface temperature may not be particularly useful for early detection. What is suggested here is not an analysis of trends in the surface temperature field or any of its spatial averages, but rather an integrating factor or integrator, a single measure of global change that could be considered a test of significant change for the entire global system. Preferably, this global change integrator would vary slowly and would take into account many of the causes of climate change, with a relatively large signal-to-noise ratio. Such an integrator could be monitored, and abrupt or accelerated changes could serve as an early warning signal for policy makers and the public. Earlier work has suggested that temperature has much less short-term and small-scale noise in the lower stratosphere, and thus the global warming signal at that level might be more easily deconvoluted, because the cooling rate near the 200-mb level is almost constant with latitude. A study of the temperature signal at this pressure level might show a clearer trend due to increased levels of greenhouse gases, but it would yield information about the troposphere only by inference.

  6. The Holocene temperature conundrum

    PubMed Central

    Liu, Zhengyu; Zhu, Jiang; Rosenthal, Yair; Zhang, Xu; Otto-Bliesner, Bette L.; Timmermann, Axel; Smith, Robin S.; Lohmann, Gerrit; Zheng, Weipeng; Elison Timm, Oliver

    2014-01-01

    A recent temperature reconstruction of global annual temperature shows Early Holocene warmth followed by a cooling trend through the Middle to Late Holocene [Marcott SA, et al., 2013, Science 339(6124):1198–1201]. This global cooling is puzzling because it is opposite from the expected and simulated global warming trend due to the retreating ice sheets and rising atmospheric greenhouse gases. Our critical reexamination of this contradiction between the reconstructed cooling and the simulated warming points to potentially significant biases in both the seasonality of the proxy reconstruction and the climate sensitivity of current climate models. PMID:25114253

  7. The Holocene temperature conundrum.

    PubMed

    Liu, Zhengyu; Zhu, Jiang; Rosenthal, Yair; Zhang, Xu; Otto-Bliesner, Bette L; Timmermann, Axel; Smith, Robin S; Lohmann, Gerrit; Zheng, Weipeng; Elison Timm, Oliver

    2014-08-26

    A recent temperature reconstruction of global annual temperature shows Early Holocene warmth followed by a cooling trend through the Middle to Late Holocene [Marcott SA, et al., 2013, Science 339(6124):1198-1201]. This global cooling is puzzling because it is opposite from the expected and simulated global warming trend due to the retreating ice sheets and rising atmospheric greenhouse gases. Our critical reexamination of this contradiction between the reconstructed cooling and the simulated warming points to potentially significant biases in both the seasonality of the proxy reconstruction and the climate sensitivity of current climate models. PMID:25114253

  8. Tropical Pacific Trends in SODA and CMIP5

    NASA Astrophysics Data System (ADS)

    Yang, C.; Giese, B. S.

    2012-12-01

    Long-term trends of tropical Pacific temperature and dynamics are investigated using an ocean reanalysis (Simple Ocean Data Assimilation SODA 2.2.6) and historical runs of Coupled Model Intercomparison Project Phase 5 (CMIP5). The ocean reanalysis is constructed from an ensemble of individual ocean reanalyses that span the period from 1865 to 2010. The reanalysis assimilates Sea Surface Temperature (SST) observations and forcing for the reanalysis comes from the 20th Century Reanalysis project (20CRv2). The CMIP5 historical runs extend from 1850 to 2005. In SODA 2.2.6, tropical Pacific SST has a slight cooling trend in the central tropical Pacific Ocean, accompanied by a strong cooling temperature trend in the subsurface ocean located at around 150m in the central tropical Pacific Ocean. To explore the dynamic changes associated with these temperature trends we focus on trends of the STCs (Sub-tropical Cells). The tropical Pacific STC consists of equatorial upwelling, surface Ekman flow, subduction over the subtropical Ocean and equatorward pycnocline flow. The reanalysis shows that the STCs transport increases in the last century, resulting in increasing equatorial upwelling that brings cold water from the deep ocean to cool the surface. Analysis of the surface wind fields shows that consistent with the cooler eastern tropical Pacific there is stronger zonal wind stress over the tropical Pacific that strengthens the transport of the STCs. In contrast with the reanalysis, most of the CMIP5 models show a warming trend of tropical Pacific SST accompanied by weaker STCs. The CMIP5 models have a weakening trend of zonal wind stress consistent with the weakening of the STCs. Also in contrast with the reanalysis, the CMIP5 models show a subsurface temperature cooling in the western tropical Pacific Ocean due to the shoaling of the thermocline that results from weaker wind stress. The role of increasing heat flux on SST over the western tropical Pacific Ocean will also be discussed.

  9. Trends in Cochlear Implants

    PubMed Central

    Zeng, Fan-Gang

    2004-01-01

    More than 60,000 people worldwide use cochlear implants as a means to restore functional hearing. Although individual performance variability is still high, an average implant user can talk on the phone in a quiet environment. Cochlear-implant research has also matured as a field, as evidenced by the exponential growth in both the patient population and scientific publication. The present report examines current issues related to audiologic, clinical, engineering, anatomic, and physiologic aspects of cochlear implants, focusing on their psychophysical, speech, music, and cognitive performance. This report also forecasts clinical and research trends related to presurgical evaluation, fitting protocols, signal processing, and postsurgical rehabilitation in cochlear implants. Finally, a future landscape in amplification is presented that requires a unique, yet complementary, contribution from hearing aids, middle ear implants, and cochlear implants to achieve a total solution to the entire spectrum of hearing loss treatment and management. PMID:15247993

  10. Land Cover Trends Project

    USGS Publications Warehouse

    Acevedo, William

    2006-01-01

    The Land Cover Trends Project is designed to document the types, rates, causes, and consequences of land cover change from 1973 to 2000 within each of the 84 U.S. Environmental Protection Agency (EPA) Level III ecoregions that span the conterminous United States. The project's objectives are to: * Develop a comprehensive methodology using probability sampling and change analysis techniques and Landsat Multispectral Scanner (MSS), Thematic Mapper (TM), and Enhanced Thematic Mapper (ETM) data for estimating regional land cover change. * Characterize the spatial and temporal characteristics of conterminous U.S. land cover change for five periods from 1973 to 2000 (nominally 1973, 1980, 1986, 1992, and 2000). * Document the regional driving forces and consequences of change. * Prepare a national synthesis of land cover change.

  11. Testing reanalysis datasets in Antarctica: Trends, persistence properties and trend significance

    E-print Network

    Wang, Yang; Havlin, Shlomo

    2015-01-01

    The reanalysis datasets provide very important sources for investigating the climate dynamics and climate changes in Antarctica. In this paper, three major reanalysis data are compared with Antarctic station data over the last 35 years: the National Centers for Environmental Prediction and the National Center for Atmospheric Research reanalysis (NCEP1), NCEP-DOE Reanalysis 2 (NCEP2), and the European Centre for Medium-Range Weather Forecasts Interim Re-Analysis (ERA-Interim). In our assessment, we compare the linear trends, the fluctuations around the trends, the persistence properties and the significance level of warming trends in the reanalysis data with the observational ones. We find that NCEP1 and NCEP2 show spurious warming trends in all parts of Antarctica except the Peninsula, while ERA-Interim is quite reliable except at Amundsen-Scott. To investigate the persistence of the data sets, we consider the lag-1 autocorrelation $C(1)$ and the Hurst exponent. While $C(1)$ varies quite erratically in differ...

  12. Non-Linear Concentration-Response Relationships between Ambient Ozone and Daily Mortality