WorldWideScience

Sample records for greenness temperature precipitation

  1. Temperature and snowfall trigger alpine vegetation green-up on the world's roof.

    Science.gov (United States)

    Chen, Xiaoqiu; An, Shuai; Inouye, David W; Schwartz, Mark D

    2015-10-01

    Rapid temperature increase and its impacts on alpine ecosystems in the Qinghai-Tibetan Plateau, the world's highest and largest plateau, are a matter of global concern. Satellite observations have revealed distinctly different trend changes and contradicting temperature responses of vegetation green-up dates, leading to broad debate about the Plateau's spring phenology and its climatic attribution. Large uncertainties in remote-sensing estimates of phenology significantly limit efforts to predict the impacts of climate change on vegetation growth and carbon balance in the Qinghai-Tibetan Plateau, which are further exacerbated by a lack of detailed ground observation calibration. Here, we revealed the spatiotemporal variations and climate drivers of ground-based herbaceous plant green-up dates using 72 green-up datasets for 22 herbaceous plant species at 23 phenological stations, and corresponding daily mean air temperature and daily precipitation data from 19 climate stations across eastern and southern parts of the Qinghai-Tibetan Plateau from 1981 to 2011. Results show that neither the continuously advancing trend from 1982 to 2011, nor a turning point in the mid to late 1990s as reported by remote-sensing studies can be verified by most of the green-up time series, and no robust evidence for a warmer winter-induced later green-up dates can be detected. Thus, chilling requirements may not be an important driver influencing green-up responses to spring warming. Moreover, temperature-only control of green-up dates appears mainly at stations with relatively scarce preseason snowfall and lower elevation, while coupled temperature and precipitation controls of green-up dates occur mostly at stations with relatively abundant preseason snowfall and higher elevation. The diversified interactions between snowfall and temperature during late winter to early spring likely determine the spatiotemporal variations of green-up dates. Therefore, prediction of vegetation growth

  2. Green and red luminescence in co-precipitation synthesized Pr:LuAG nanophosphor

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, S. Arun; Kumar, K. Ashok; Gunaseelan, M.; Senthilselvan, J., E-mail: jsselvan@hotmail.com [Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai–600 025, Tamil Nadu (India); Asokan, K. [Materials Science Group, Inter University Accelerator Centre, New Delhi-110067 (India)

    2016-05-06

    Pr:LuAG nanophosphor is an effective candidate in magnetic resonance imaging coupled positron emission tomography (MRI-PET) for medical imaging and scintillator applications. LuAG:Pr (0.05, 0.15 mol%) nanoscale ceramic powders were synthesized by co-precipitation method using urea as precipitant. Effect of antisite defect on structure and luminescence behavior was investigated. Pr:LuAG nanoceramic powders are found crystallized in cubic structure by high temperature calcination at 1400 °C and it shows antisite defect. HR-SEM analysis revealed spherically shaped Pr:LuAG nanoceramic particulate powders with ∼100 nm size. By the excitation at 450 nm, Pr:LuAG nanophosphor exhibit green to red luminescence in the wavelength range of 520 to 680 nm, which is originated from multiplet transition of Pr{sup 3+} ions.

  3. Distributing urban resilience to extreme precipitation events with green infrastructure

    Science.gov (United States)

    Montalto, F. A.; Catalano De Sousa, M.; Yu, Z.

    2013-12-01

    New urban green spaces are being designed to manage stormwater, but their performance in a changing climate is untested. Key questions pertain to the ability of these systems to mitigate flood and sewer overflow concerns during impact of extreme events on, and to withstand (biologically and physically) increased frequency and intensity of drought and flood conditions. In this presentation, we present field data characterizing performance of a bioretention area, a stormwater treatment wetland, and a green roof under Hurricane Irene (2011), Superstorm Sandy (2012), and a variety of extreme precipitation events during the summer of 2013. Specifically, we characterize the fate and volume of incident runon and/or precipitation to the facilities during these extreme events, and compare them to long term monitored performance metrics. We also present laboratory test results documenting how vegetation in these facilities stands up to simulated flood and drought conditions. The results are discussed in the context of predicted climate change, specifically associated with the amount and timing of precipitation.

  4. Investigation of Asphaltene Precipitation at Elevated Temperature

    DEFF Research Database (Denmark)

    Andersen, Simon Ivar; Lindeloff, Niels; Stenby, Erling Halfdan

    1998-01-01

    In order to obtain quantitative data on the asphaltene precipitation induced by the addition of n-alkane (heptane) at temperatures above the normal boiling point of the precipitant, a high temperature/high pressure filtration apparatus has been constructed. Oil and alkane are mixed...

  5. Association analysis between spatiotemporal variation of vegetation greenness and precipitation/temperature in the Yangtze River Basin (China).

    Science.gov (United States)

    Cui, Lifang; Wang, Lunche; Singh, Ramesh P; Lai, Zhongping; Jiang, Liangliang; Yao, Rui

    2018-05-23

    The variation in vegetation greenness provides good understanding of the sustainable management and monitoring of land surface ecosystems. The present paper discusses the spatial-temporal changes in vegetation and controlling factors in the Yangtze River Basin (YRB) using Global Inventory Modeling and Mapping Studies (GIMMS) Normalized Difference Vegetation Index (NDVI) for the period 2001-2013. Theil-Sen Median trend analysis, Pearson correlation coefficients, and residual analysis have been used, which shows decreasing trend of the annual mean NDVI over the whole YRB. Spatially, the regions with significant decreasing trends were mainly located in parts of central YRB, and pronounced increasing trends were observed in parts of the eastern and western YRB. The mean NDVI during spring and summer seasons increased, while it decreased during autumn and winter seasons. The seasonal mean NDVI shows spatial heterogeneity due to the vegetation types. The correlation analysis shows a positive relation between NDVI and temperature over most of the YRB, whereas NDVI and precipitation show a negative correlation. The residual analysis shows an increase in NDVI in parts of eastern and western YRB and the decrease in NDVI in the small part of Yangtze River Delta (YRD) and the mid-western YRB due to human activities. In general, climate factors were the principal drivers of NDVI variation in YRB in recent years.

  6. Detection of the relationship between peak temperature and extreme precipitation

    Science.gov (United States)

    Yu, Y.; Liu, J.; Zhiyong, Y.

    2017-12-01

    Under the background of climate change and human activities, the characteristics and pattern of precipitation have changed significantly in many regions. As the political and cultural center of China, the structure and character of precipitation in Jingjinji District has varied dramatically in recent years. In this paper, the daily precipitation data throughout the period 1960-2013 are selected for analyzing the spatial-temporal variability of precipitation. The results indicate that the frequency and intensity of precipitation presents an increasing trend. Based on the precipitation data, the maximum, minimum and mean precipitation in different temporal and spatial scales is calculated respectively. The temporal and spatial variation of temperature is obtained by using statistical methods. The relationship between temperature and precipitation in different range is analyzed. The curve relates daily precipitation extremes with local temperatures has a peak structure, increasing at the low-medium range of temperature variations but decreasing at high temperatures. The relationship between extreme precipitation is stronger in downtown than that in suburbs.

  7. Projections of precipitation, air temperature and potential ...

    African Journals Online (AJOL)

    mabouelhaggag

    Precipitation and air temperature records from 6 sites in Rwanda in the period from 1964 to 2010 are used for past/present climate assessment. Future climate projections (2010-2099) based on 3 general circulation models and 2 emission scenarios (A2 and B1) are used for climate projections. Precipitation, air temperature ...

  8. Uranium peroxide precipitate drying temperature relationships

    Energy Technology Data Exchange (ETDEWEB)

    Rodgers, C.; Dyck, B., E-mail: chick_rodgers@cameco.com [Cameco Corp., Saskatoon, SK (Canada)

    2010-07-01

    Cameco Corporation is in the process of revitalizing the mill at its Key Lake operation in northern Saskatchewan. The current Key Lake process employs ammonia stripping and ammonia precipitation. As part of the revitalization, the company is considering installing strong acid stripping in solvent extraction as used at its Rabbit Lake operation. This change would lead to using hydrogen peroxide for uranium precipitation. As part of the process evaluation, tests were carried out to study how changes in the temperature of an indirect fired dryer affected the properties of uranium peroxide [yellowcake] precipitate. This paper discusses the results of the test work, including the relationships between drying temperature and the following: (author)

  9. Assessing onset and length of greening period in six vegetation types in Oaxaca, Mexico, using NDVI-precipitation relationships.

    Science.gov (United States)

    Gómez-Mendoza, L; Galicia, L; Cuevas-Fernández, M L; Magaña, V; Gómez, G; Palacio-Prieto, J L

    2008-07-01

    Variations in the normalized vegetation index (NDVI) for the state of Oaxaca, in southern Mexico, were analyzed in terms of precipitation anomalies for the period 1997-2003. Using 10-day averages in NDVI data, obtained from AVHRR satellite information, the response of six types of vegetation to intra-annual and inter-annual fluctuations in precipitation were examined. The onset and temporal evolution of the greening period were studied in terms of precipitation variations through spectral analysis (coherence and phase). The results indicate that extremely dry periods, such as those observed in 1997 and 2001, resulted in low values of NDVI for much of Oaxaca, while good precipitation periods produced a rapid response (20-30 days of delay) from a stressed to a non-stressed condition in most vegetation types. One of these rapid changes occurred during the transition from dry to wet conditions during the summer of 1998. As in many parts of the tropics and subtropics, the NDVI reflects low frequency variations in precipitation on several spatial scales. Even after long dry periods (2001-2002), the various regional vegetation types are capable of recovering when a good rainy season takes place, indicating that vegetation types such as the evergreen forests in the high parts of Oaxaca respond better to rainfall characteristics (timing, amount) than to temperature changes, as is the case in most mid-latitudes. This finding may be relevant to prepare climate change scenarios for forests, where increases in surface temperature and precipitation anomalies are expected.

  10. Modeling and optimization of green tea precipitation for the recovery of catechins

    NARCIS (Netherlands)

    Madalena Monsanto, M.F.; Hooshyar, N.; Meuldijk, J.; Zondervan, E.

    2014-01-01

    Green tea catechins are claimed to have several health benefits (e.g. antioxidant, antimutagenic and antiviral) with increasing applications in the food and pharmaceutical markets. By using the tea creaming effect and by enhancing it, as a phase separation via precipitation, it is possible to

  11. Environmental Radioactivity, Temperature, and Precipitation.

    Science.gov (United States)

    Riland, Carson A.

    1996-01-01

    Reports that environmental radioactivity levels vary with temperature and precipitation and these effects are due to radon. Discusses the measurement of this environmental radioactivity and the theory behind it. (JRH)

  12. Removal of malachite green by adsorption and precipitation using aminopropyl functionalized magnesium phyllosilicate

    International Nuclear Information System (INIS)

    Lee, Young-Chul; Kim, Eui Jin; Yang, Ji-Won; Shin, Hyun-Jae

    2011-01-01

    Highlights: → Preparation of aminopropyl functionalized magnesium phyllosilicate (AMP clay). → Characterization of AMP clay and AMP clay-malachite green (MG) mixture. → Novel precipitation mechanism including MG fading plus collapsed AMP clay. → Adsorption kinetics and thermodynamics of MG using AMP clay. - Abstract: We report a method for the removal of malachite green (MG) by adsorption and precipitation using nano-sized aminopropyl functionalized magnesium phyllosilicate (AMP) clay. MG, which is used in aquaculture and fisheries, is a carcinogenic and mutagenic compound. In response to these health risks, many efforts have been focused on adsorption of MG onto various adsorbents, which is a versatile and widely used technique for removing MG from water. Herein, we describe the adsorption and precipitation of MG using AMP clay, as well as the alkaline fading phenomenon of MG. In this study, prepared AMP clay and the precipitate product after the reaction of MG-AMP clay mixture were characterized. In addition, adsorption isotherms and kinetics, as well as thermodynamic studies are presented. Based on the results, we suggest a macro- and microscopic removal mechanism for the adsorption and precipitation of MG using AMP clay. An AMP clay dosage of 0.1 mg mL -1 exhibited a maximum removal capacity of 334.80 mg g -1 and 81.72% MG removal efficiency. With further increases of the AMP clay dosage, removal capacity by AMP clay gradually decreased; at dosage above 0.2 mg mL -1 of AMP clay, the removal efficiency reached 100%.

  13. Removal of malachite green by adsorption and precipitation using aminopropyl functionalized magnesium phyllosilicate

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Young-Chul [Department of Chemical and Biomolecular Engineering (BK21 Program), KAIST, 335 Gwahak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Kim, Eui Jin [Department of Chemical and Biochemical Engineering, Chosun University, Seosuk-dong, Dong-gu, Gwangju 501-759 (Korea, Republic of); Yang, Ji-Won [Department of Chemical and Biomolecular Engineering (BK21 Program), KAIST, 335 Gwahak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Shin, Hyun-Jae, E-mail: shinhj@chosun.ac.kr [Department of Chemical and Biochemical Engineering, Chosun University, Seosuk-dong, Dong-gu, Gwangju 501-759 (Korea, Republic of)

    2011-08-15

    Highlights: {yields} Preparation of aminopropyl functionalized magnesium phyllosilicate (AMP clay). {yields} Characterization of AMP clay and AMP clay-malachite green (MG) mixture. {yields} Novel precipitation mechanism including MG fading plus collapsed AMP clay. {yields} Adsorption kinetics and thermodynamics of MG using AMP clay. - Abstract: We report a method for the removal of malachite green (MG) by adsorption and precipitation using nano-sized aminopropyl functionalized magnesium phyllosilicate (AMP) clay. MG, which is used in aquaculture and fisheries, is a carcinogenic and mutagenic compound. In response to these health risks, many efforts have been focused on adsorption of MG onto various adsorbents, which is a versatile and widely used technique for removing MG from water. Herein, we describe the adsorption and precipitation of MG using AMP clay, as well as the alkaline fading phenomenon of MG. In this study, prepared AMP clay and the precipitate product after the reaction of MG-AMP clay mixture were characterized. In addition, adsorption isotherms and kinetics, as well as thermodynamic studies are presented. Based on the results, we suggest a macro- and microscopic removal mechanism for the adsorption and precipitation of MG using AMP clay. An AMP clay dosage of 0.1 mg mL{sup -1} exhibited a maximum removal capacity of 334.80 mg g{sup -1} and 81.72% MG removal efficiency. With further increases of the AMP clay dosage, removal capacity by AMP clay gradually decreased; at dosage above 0.2 mg mL{sup -1} of AMP clay, the removal efficiency reached 100%.

  14. Trends in extreme temperature and precipitation in Muscat, Oman

    Directory of Open Access Journals (Sweden)

    L. N. Gunawardhana

    2014-09-01

    Full Text Available Changes in frequency and intensity of weather events often result in more frequent and intensive disasters such as flash floods and persistent droughts. In Oman, changes in precipitation and temperature have already been detected, although a comprehensive analysis to determine long-term trends is yet to be conducted. We analysed daily precipitation and temperature records in Muscat, the capital city of Oman, mainly focusing on extremes. A set of climate indices, defined in the RClimDex software package, were derived from the longest available daily series (precipitation over the period 1977–2011 and temperature over the period 1986–2011. Results showed significant changes in temperature extremes associated with cooling. Annual maximum value of daily maximum temperature (TX, on average, decreased by 1°C (0.42°C/10 year. Similarly, the annual minimum value of daily minimum temperature (TN decreased by 1.5°C (0.61°C/10 year, which, on average, cooled at a faster rate than the maximum temperature. Consequently, the annual count of days when TX > 45°C (98th percentile decreased from 8 to 3, by 5 days. Similarly, the annual count of days when TN < 15°C (2nd percentile increased from 5 to 15, by 10 days. Annual total precipitation averaged over the period 1977–2011 is 81 mm, which shows a tendency toward wetter conditions with a 6 mm/10 year rate. There is also a significant tendency for stronger precipitation extremes according to many indices. The contribution from very wet days to the annual precipitation totals steadily increases with significance at 75% level. When The General Extreme Value (GEV probability distribution is fitted to annual maximum 1-day precipitation, the return level of a 10-year return period in 1995–2011 was estimated to be 95 mm. This return level in the recent decade is about 70% higher than the return level for the period of 1977–1994. These results indicate that the long-term wetting signal apparent in total

  15. Will the warmer temperature bring the more intensity precipitation?

    Science.gov (United States)

    Yutong, Z., II; Wang, T.

    2017-12-01

    Will the warmer temperature bring the more intensity precipitation?Over the past several decades, changes in climate are amplified over the Tibetan Plateau(TP), with warming trend almost being twice as large as the global average. In sharp contrast, there is a large spatial discrepancy of the variations in precipitation extremes, with increasing trends found in the southern and decreasing trends in central TP. These features motivate are urgent need for an observation-based understanding of how precipitation extremes respond to climate change. Here we examine the relation between precipitation intensity with atmospheric temperature, dew point temperature (Td) and convective available potential energy (CAPE) in Tibet Plateau. Owing to the influences of the westerlies and Indian monsoon on Tibetan climate, the stations can be divided into three sub-regions in TP: the westerlies region (north of 35°N, N = 28), the monsoon region (south of 30°N in TP, N = 31), and the transition region (located between 30°N and 35°N, N = 48). We found that the intensity precipitation does not follow the C-C relation and there is a mix of positive and negative slope. To better understand why different scaling occurs with temperature in district region, using the dew point temperature replace the temperature, although there is significant variability in relative humidity values, at most stations, there appears to be a general increase in relative humidity associated. It is likely that the observed rise in relative humidity can assist in explaining the negative scaling of extreme precipitation at westerlies domain and monsoon domain, with the primary reason why precipitation extremes expected to increase follows from the fact that a warmer atmosphere can "hold" more moisture. This suggests that not only on how much the moisture the atmosphere can hold, but on how much moisture exits in atmosphere. To understand the role of dynamic on extreme precipitation, we repeat the precipitation

  16. Strong increase in convective precipitation in response to higher temperatures

    DEFF Research Database (Denmark)

    Berg, P.; Moseley, C.; Härter, Jan Olaf Mirko

    2013-01-01

    Precipitation changes can affect society more directly than variations in most other meteorological observables, but precipitation is difficult to characterize because of fluctuations on nearly all temporal and spatial scales. In addition, the intensity of extreme precipitation rises markedly...... at higher temperature, faster than the rate of increase in the atmosphere's water-holding capacity, termed the Clausius-Clapeyron rate. Invigoration of convective precipitation (such as thunderstorms) has been favoured over a rise in stratiform precipitation (such as large-scale frontal precipitation......) as a cause for this increase , but the relative contributions of these two types of precipitation have been difficult to disentangle. Here we combine large data sets from radar measurements and rain gauges over Germany with corresponding synoptic observations and temperature records, and separate convective...

  17. Cladonia lichens on extensive green roofs: evapotranspiration, substrate temperature, and albedo.

    Science.gov (United States)

    Heim, Amy; Lundholm, Jeremy

    2013-01-01

    Green roofs are constructed ecosystems that provide ecosystem services in urban environments. Shallow substrate green roofs subject the vegetation layer to desiccation and other environmental extremes, so researchers have evaluated a variety of stress-tolerant vegetation types for green roof applications. Lichens can be found in most terrestrial habitats.  They are able to survive extremely harsh conditions, including frequent cycles of desiccation and rehydration, nutrient-poor soil, fluctuating temperatures, and high UV intensities. Extensive green roofs (substrate depth green roofs.  In a modular green roof system, we tested the effect of Cladonia lichens on substrate temperature, water loss, and albedo compared to a substrate-only control. Overall, the Cladonia modules had significantly cooler substrate temperatures during the summer and significantly warmer temperatures during the fall.  Additionally, the Cladonia modules lost significantly less water than the substrate-only control. This implies that they may be able to benefit neighboring vascular plant species by reducing water loss and maintaining favorable substrate temperatures.

  18. Precipitation of {gamma}' phase in {delta}-precipitated Alloy 718 during deformation at elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Nalawade, S.A. [Structural Metallurgy Section, Mechanical Metallurgy Section, Bhabha Atomic Research Centre, Mumbai 400085 (India); Sundararaman, M., E-mail: msraman@barc.gov.in [Structural Metallurgy Section, Mechanical Metallurgy Section, Bhabha Atomic Research Centre, Mumbai 400085 (India); Singh, J.B.; Verma, A.; Kishore, R. [Structural Metallurgy Section, Mechanical Metallurgy Section, Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2010-05-15

    Alloy 718 samples aged to precipitate only {delta} particles (with maximum volume fraction) when tensile deformed to fracture at elevated temperatures revealed precipitation of {gamma}' and {gamma}'' phases. The {gamma}' precipitation was found to precede the {gamma}'' phase precipitation unlike in the case of specimens subjected to standard ageing treatment where both the {gamma}' and the {gamma}'' phases precipitate simultaneously. This sequence is explained on the basis of the relative concentration of Al, Ti and Nb in the matrix of {delta} precipitated Alloy 718 microstructure. The precipitation sequence was consistent with the Cozar and Pineau's model that predicts such sequences on the basis of (Al + Ti) to Nb atom ratios.

  19. High temperature tensile properties and deep drawing of fully green composites

    Directory of Open Access Journals (Sweden)

    2009-01-01

    Full Text Available In recent years, research and development of materials using biomass sources are much expected to construct a sustainable society. The so-called green composite consisting of natural fibers and biodegradable resin, is one of the most promising materials in developing biomass products. In this study, especially, we focus on the tensile deformation behavior of the green composites reinforced with ramie woven fabrics at high temperature. The results show that the fracture strain at high temperatures increases larger than that of room temperature, and initial deformation resistance of the composites seen at room temperature does not appear at high temperatures. Thus, several conditions to cause more deformability of the green composites were found. Finally, in order to utilize such deformability, Lankford-values of the green composites were clarified, and deep drawing was carried out for sheet materials made of the green composites.

  20. Linkage Between Hourly Precipitation Events and Atmospheric Temperature Changes over China during the Warm Season

    Science.gov (United States)

    Miao, Chiyuan; Sun, Qiaohong; Borthwick, Alistair G. L.; Duan, Qingyun

    2016-01-01

    We investigated changes in the temporospatial features of hourly precipitation during the warm season over mainland China. The frequency and amount of hourly precipitation displayed latitudinal zonation, especially for light and moderate precipitation, which showed successive downward change over time in northeastern and southern China. Changes in the precipitation amount resulted mainly from changes in frequency rather than changes in intensity. We also evaluated the linkage between hourly precipitation and temperature variations and found that hourly precipitation extreme was more sensitive to temperature than other categories of precipitation. A strong dependency of hourly precipitation on temperature occurred at temperatures colder than the median daily temperature; in such cases, regression slopes were greater than the Clausius-Clapeyron (C-C) relation of 7% per degree Celsius. Regression slopes for 31.6%, 59.8%, 96.9%, and 99.1% of all stations were greater than 7% per degree Celsius for the 75th, 90th, 99th, and 99.9th percentiles for precipitation, respectively. The mean regression slopes within the 99.9th percentile of precipitation were three times the C-C rate. Hourly precipitation showed a strong negative relationship with daily maximum temperature and the diurnal temperature range at most stations, whereas the equivalent correlation for daily minimum temperature was weak. PMID:26931350

  1. Reassessing the role of temperature in precipitation oxygen isotopes across the eastern and central United States through weekly precipitation-day data

    Science.gov (United States)

    Akers, Pete D.; Welker, Jeffrey M.; Brook, George A.

    2017-09-01

    Air temperature is correlated with precipitation oxygen isotope (δ18Oprcp) variability for much of the eastern and central United States, but the nature of this δ18Oprcp-temperature relationship is largely based on data coarsely aggregated at a monthly resolution. We constructed a database of 6177 weeks of isotope and precipitation-day air temperature data from 25 sites to determine how more precise data change our understanding of this classic relationship. Because the δ18Oprcp-temperature relationship is not perfectly linear, trends in the regression residuals suggest the influence of additional environmental factors such as moisture recycling and extratropical cyclone interactions. Additionally, the temporal relationships between δ18Oprcp and temperature observed in the weekly data at individual sites can explain broader spatial patterns observed across the study region. For 20 of 25 sites, the δ18Oprcp-temperature relationship slope is higher for colder precipitation than for warmer precipitation. Accordingly, northern and western sites with relatively more cold precipitation events have steeper overall relationships with higher slope values than southeastern sites that have more warm precipitation events. Although the magnitude of δ18Oprcp variability increases to the north and west, the fraction of δ18Oprcp variability explained by temperature increases due to wider annual temperature ranges, producing stronger relationships in these regions. When our δ18Oprcp-temperature data are grouped by month, we observe significant variations in the relationship from month to month. This argues against a principal causative role for temperature and suggests the existence of an alternative environmental control on δ18Oprcp values that simply covaries seasonally with temperature.

  2. Temperature-precipitation relationship of the Common Era in northern Europe

    Science.gov (United States)

    Luoto, Tomi P.; Nevalainen, Liisa

    2018-05-01

    Due to the lack of knowledge on dynamics of the North Atlantic Oscillation (NAO) prior to the last millennium, synchronized records of air temperature and precipitation variability are needed to understand large-scale drivers of the hydroclimate. Here, we use completely synchronized paleolimnological proxy-based records of air temperature and effective precipitation from two Scandinavian lakes with ˜2000-year sediment profiles. We show that the relationship between air temperature and precipitation (T/P ratio) is synchronous in both study sites throughout the records suggesting warm and dry conditions at ˜300-1100 CE and cold and wet conditions at ˜1200-1900 CE. Owing to the significantly increased air temperatures, the most recent T/P ratio has again turned positive. During the first millennium of the Common Era, the T/P mimics patterns in Southern Oscillation index, whereas the second millennium shows response to the NAO index but is also concurrent with solar irradiance shifts. Since our T/P reconstruction is mostly linked with the NAO, we propose the T/P ratio as an indicator of the NAO. Our results from the coherent records provide first-time knowledge on the long-term temperature-precipitation relationship in Northern Europe that increase understanding of the comprehensive hydroclimate system in the region and the NAO dynamics also further back in time.

  3. Sensitivities of dry season runoff to precipitation and temperature in southern Sierra Nevada streams

    Science.gov (United States)

    Safeeq, M.; Hunsaker, C. T.; Bales, R. C.

    2016-12-01

    In a mediterranean climate, dry season runoff sustains water supply and supports aquatic habitat and other ecosystems. Precipitation and temperature directly, by regulating recharge and evapotranspiration (ET), and indirectly, by regulating amount and timing of snowmelt, control the dry season runoff in the Sierra Nevada. Here, we explored relative impacts of precipitation and temperature variability on dry season runoff using path analysis. Specific objectives include: (i) to quantify the direct and indirect impacts of precipitation and temperature on 7-day average minimum flow (Qmin) and (ii) to explore the role of preceding year Qmin on fall season runoff (QF). We used daily runoff, air temperature, precipitation, and snow water equivalent (SWE) over 2004-2015 for the ten catchments in the Kings River Experimental Watersheds. For path analysis model of Qmin, we defined annual precipitation and temperature as exogenous variables and peak SWE, day of snow disappearance, and Qmin as endogenous variables. For QF, we defined current year fall precipitation and preceding year Qmin as exogenous variables and current year QF as an endogenous variable. Path analysis results for Qmin show precipitation as a dominant driver when compared to temperature, peak SWE, and day of snow disappearance. However, in half of the catchments that are mostly located at higher elevations the impact of temperature on Qmin was either comparable or exceeded that of precipitation. This relatively high sensitivity of Qmin to air temperature in high elevation catchments is consistent with the earlier findings of increased ET in proportion to warming. The direct effects of peak SWE and day of snow disappearance on Qmin were limited, and indirect effects of temperature and precipitation via peak SWE and day of snow disappearance were not significant. The preceding year Qmin and fall precipitation showed comparable impacts on QF, indicating that the storage in the preceding year modulates current

  4. Temperature and Precipitation trends in Kashmir valley, North Western Himalayas

    Science.gov (United States)

    Shafiq, Mifta Ul; Rasool, Rehana; Ahmed, Pervez; Dimri, A. P.

    2018-01-01

    Climate change has emerged as an important issue ever to confront mankind. This concern emerges from the fact that our day-to-day activities are leading to impacts on the Earth's atmosphere that has the potential to significantly alter the planet's shield and radiation balance. Developing countries particularly whose income is particularly derived from agricultural activities are at the forefront of bearing repercussions due to changing climate. The present study is an effort to analyze the changing trends of precipitation and temperature variables in Kashmir valley along different elevation zones in the north western part of India. As the Kashmir valley has a rich repository of glaciers with its annual share of precipitation, slight change in the temperature and precipitation regime has far reaching environmental and economic consequences. The results from Indian Meteorological Department (IMD) data of the period 1980-2014 reveals that the annual mean temperature of Kashmir valley has increased significantly. Accelerated warming has been observed during 1980-2014, with intense warming in the recent years (2001-2014). During the period 1980-2014, steeper increase, in annual mean maximum temperature than annual mean minimum temperature, has been observed. In addition, mean maximum temperature in plain regions has shown higher rate of increase when compared with mountainous areas. In case of mean minimum temperature, mountainous regions have shown higher rate of increase. Analysis of precipitation data for the same period shows a decreasing trend with mountainous regions having the highest rate of decrease which can be quite hazardous for the fragile mountain environment of the Kashmir valley housing a large number of glaciers.

  5. Corresponding Relation between Warm Season Precipitation Extremes and Surface Air Temperature in South China

    Institute of Scientific and Technical Information of China (English)

    SUN; Wei; LI; Jian; YU; Ru-Cong

    2013-01-01

    Hourly data of 42 rain gauges over South China during 1966–2005 were used to analyze the corresponding relation between precipitation extremes and surface air temperature in the warm season(May to October).The results show that below 25℃,both daily and hourly precipitation extremes in South China increase with rising temperature.More extreme events transit to the two-time Clausius-Clapeyron(CC)relationship at lower temperatures.Daily as well as hourly precipitation extremes have a decreasing tendency nearly above 25℃,among which the decrease of hourly extremes is much more significant.In order to investigate the efects of rainfall durations,hourly precipitation extremes are presented by short duration and long duration precipitation,respectively.Results show that the dramatic decrease of hourly rainfall intensities above 25℃ is mainly caused by short duration precipitation,and long duration precipitation extremes rarely occur in South China when surface air temperature surpasses 28℃.

  6. Detecting Variation Trends of Temperature and Precipitation for the Dadu River Basin, China

    Directory of Open Access Journals (Sweden)

    Ying Wu

    2016-01-01

    Full Text Available This study analyzes the variation trends of temperature and precipitation in the Dadu River Basin of China based on observed records from fourteen meteorological stations. The magnitude of trends was estimated using Sen’s linear method while its statistical significance was evaluated using Mann-Kendall’s test. The results of analysis depict increase change from northwest to southeast of annual temperature and precipitation in space. In temporal scale, the annual temperature showed significant increase trend and the annual precipitation showed increase trend. For extreme indices, the trends for temperature are more consistent in the region compared to precipitation. This paper has practical meanings for an effective management of climate risk and provides a foundation for further study of hydrological situation in this river basin.

  7. Variability in temperature, precipitation and river discharge in the Baltic States

    Energy Technology Data Exchange (ETDEWEB)

    Kriauciuniene, J.; Meilutyte-Barauskiene, D.; Sarauskiene, D. (Lithuanian Energy Inst., Kaunas (Lithuania), Lab. of Hydrology); Reihan, A. (Tallinn Univ. of Technology (Estonia), Inst. of Environmental Engineering); Koltsova, T.; Lizuma, L. (Latvian Hydrometeorological Agency, Riga (LV))

    2012-07-01

    The climate change impact on water resources is observed in all the Baltic States. These processes became more evident in the last decades. Although the territory of the Baltic States (Lithuania, Latvia, Estonia) is not large (175000 km2), the climatic differences are quite considerable. We performed a regionalization of the territory of the Baltic States depending on the conditions of river runoff formation which can be defined according to percentages of the river feeding sources (precipitation, snowmelt, groundwater). Long-term series of temperature (40 stations), precipitation (59 stations) and river discharge (77 stations) were used to compose ten regional series. This paper addresses: (1) variability in long-term regional series of temperature, precipitation and river discharge over a long period (1922-2007); (2) changes in regional series, comparing the periods 1991-2007 and 1931-1960 with the reference period (1961-1990), and (3) the impact of temperature and precipitation changes on regional river discharge. (orig.)

  8. TEMPERATURE AND PRECIPITATION CHANGES IN TÂRGU-MURES (ROMANIA FROM PERIOD 1951-2010

    Directory of Open Access Journals (Sweden)

    O.Rusz

    2012-03-01

    Full Text Available Temperature and precipitation changes in Târgu Mures (Romania from period 1951-2010. The analysis was made based upon meteorological data collected at Târgu Mures meteorological station (Romania, Mures county, lat. 46°32’N, lon. 24°32’E, elevation 308 m, between 1951 and 2010. Several climatic parameters were studied (for instance, annual and monthly mean temperature, maximum precipitation in 24 hours, number of summer days, etc. Detected inhomogeneities are not related to instrumental causes or geographical relocation. Positive and statistical significant trends (Mann-Kendall test are indicated for: mean annual temperatures, mean temperatures of warm months, average of the maximum and minimum temperatures (annual and warm months data, number of days with mean temperature between 20.1-25.0 °C, number of days with precipitation ≥0 mm, and for all parameters of precipitation of September. The sequential version of Mann-Kendall test show a beginning of a trend in 1956 in the case of mean temperature (at same, the two and three parts regression denote this year like a moment of change, years 1965 and 1992 in the case of annual amount of precipitation. CUSUM charts indicate occurs of changes points at 1988, 2005, 2009 (mean temperature respectively at 1989, 2004 (precipitation, and at 1968, 1992 (daily temperature range. Tendencies of overlapped time series reveal a more important increase at the end of period (mainly for mean temperature. The analysis with RClimDex show for 5 extreme climate indices a significant trend: positive for summer days, warm nights, warm spell duration indicator and negative for cold nights and cold days.

  9. Long-Term Trend Analysis of Precipitation and Air Temperature for Kentucky, United States

    Directory of Open Access Journals (Sweden)

    Somsubhra Chattopadhyay

    2016-02-01

    Full Text Available Variation in quantities such as precipitation and temperature is often assessed by detecting and characterizing trends in available meteorological data. The objective of this study was to determine the long-term trends in annual precipitation and mean annual air temperature for the state of Kentucky. Non-parametric statistical tests were applied to homogenized and (as needed pre-whitened annual series of precipitation and mean air temperature during 1950–2010. Significant trends in annual precipitation were detected (both positive, averaging 4.1 mm/year for only two of the 60 precipitation-homogenous weather stations (Calloway and Carlisle counties in rural western Kentucky. Only three of the 42 temperature-homogenous stations demonstrated trends (all positive, averaging 0.01 °C/year in mean annual temperature: Calloway County, Allen County in southern-central Kentucky, and urbanized Jefferson County in northern-central Kentucky. In view of the locations of the stations demonstrating positive trends, similar work in adjacent states will be required to better understand the processes responsible for those trends and to properly place them in their larger context, if any.

  10. Temperature sensitivity of extreme precipitation events in the south-eastern Alpine forelands

    Science.gov (United States)

    Schroeer, Katharina; Kirchengast, Gottfried

    2016-04-01

    How will convective precipitation intensities and patterns evolve in a warming climate on a regional to local scale? Studies on the scaling of precipitation intensities with temperature are used to test observational and climate model data against the hypothesis that the change of precipitation with temperature will essentially follow the Clausius-Clapeyron (CC) equation, which corresponds to a rate of increase of the water holding capacity of the atmosphere by 6-7 % per Kelvin (CC rate). A growing number of studies in various regions and with varying approaches suggests that the overall picture of the temperature-precipitation relationship is heterogeneous, with scaling rates shearing off the CC rate in both upward and downward directions. In this study we investigate the temperature scaling of extreme precipitation events in the south-eastern Alpine forelands of Austria (SEA) based on a dense rain gauge net of 188 stations, with sub-daily precipitation measurements since about 1990 used at 10-min resolution. Parts of the study region are European hot-spots for severe hailstorms and the region, which is in part densely populated and intensively cultivated, is generally vulnerable to climate extremes. Evidence on historical extremely heavy short-time and localized precipitation events of several hundred mm of rain in just a few hours, resulting in destructive flash flooding, underline these vulnerabilities. Heavy precipitation is driven by Mediterranean moisture advection, enhanced by the orographic lifting at the Alpine foothills, and hence trends in positive sea surface temperature anomalies might carry significant risk of amplifying future extreme precipitation events. In addition, observations from the highly instrumented subregion of south-eastern Styria indicate a strong and robust long-term warming trend in summer of about 0.7°C per decade over 1971-2015, concomitant with a significant increase in the annual number of heat days. The combination of these

  11. Probabilistic precipitation and temperature downscaling of the Twentieth Century Reanalysis over France

    Science.gov (United States)

    Caillouet, Laurie; Vidal, Jean-Philippe; Sauquet, Eric; Graff, Benjamin

    2015-04-01

    This work proposes a daily high-resolution probabilistic reconstruction of precipitation and temperature fields in France over the last century built on the NOAA 20th century global extended atmospheric reanalysis (20CR, Compo et al., 2011). It aims at delivering appropriate meteorological forcings for continuous distributed hydrological modelling over the last 140 years. The longer term objective is to improve our knowledge of major historical hydrometeorological events having occurred outside of the last 50-year period, over which comprehensive reconstructions and observations are available. It would constitute a perfect framework for assessing the recent observed events but also future events projected by climate change impact studies. The Sandhy (Stepwise ANalogue Downscaling method for Hydrology) statistical downscaling method (Radanovics et al., 2013), initially developed for quantitative precipitation forecast, is used here to bridge the scale gap between 20CR predictors - temperature, geopotential shape, vertical velocity and relative humidity - and local predictands - precipitation and temperature - relevant for catchment-scale hydrology. Multiple predictor domains for geopotential shape are retained from a local optimisation over France using the Safran near-surface reanalysis (Vidal et al., 2010). Sandhy gives an ensemble of 125 equally plausible gridded precipitation and temperature time series over the whole 1871-2012 period. Previous studies showed that Sandhy precipitation outputs are very slightly biased at the annual time scale. Nevertheless, the seasonal precipitation signal for areas with a high interannual variability is not well simulated. Moreover, winter and summer temperatures are respectively over- and underestimated. Reliable seasonal precipitation and temperature signals are however necessary for hydrological modelling, especially for evapotranspiration and snow accumulation/snowmelt processes. Two different post-processing methods are

  12. Early-Holocene decoupled summer temperature and monsoon precipitation in southwest China

    Science.gov (United States)

    Wu, D.; Chen, F.; Chen, X.; Lv, F.; Zhou, A.; Chen, J.; Abbott, M. B.; Yu, J.

    2017-12-01

    Proxy based reconstructions of Holocene temperature have shown that both the timing and magnitude of the thermal maximum vary substantially between different regions; the simulations results from climate models also show that summers were substantially cooler over regions directly influenced by the presence of the Laurentide ice sheet during the early Holocene, whereas other regions of the Northern Hemisphere were dominated by orbital forcing. However, for lack of summer temperature reconstruction in the low latitude regions like southwestern China dominated by the Indian summer monsoon, the Holocene summer temperature variations and it underlying forcing mechanism are ambiguous. Here we present a well-dated record of pollen-based quantitative summer temperature (mean July; MJT) over the last 14000 years from Xingyun Lake, Yunnan Province, southwest China. It was found that MJT decreased during the YD event, then increased slowly until 7400 yr BP, and decreased thereafter. The MJT shows a pattern with middle Holocene maximum of MJT, indicating a different changing pattern with the carbonate oxygen isotope record (d18O) from the same core during the early Holocene (11500-7400 yr BP), which has the similar variation with speleothem d18O record from Dongge cave, both indicate the variation of monsoon precipitation with the highest precipitation occurred during the early Holocene. Therefore, we propose that the variation of summer temperature and precipitation in southwest China was decoupled during the early Holocene. However, both MJT and monsoon precipitation decreased after the middle Holocene following the boreal summer insolation. We suggest that the high precipitation with strong summer monsoon and hence higher cloud cover may depress the temperature increasing forced by increasing summer insolation during the early Holocene; while melting ice-sheet in the high latitude regions had strongly influenced the summer temperature increase during the deglacial period

  13. Complex terrain influences ecosystem carbon responses to temperature and precipitation

    Science.gov (United States)

    Reyes, W. M.; Epstein, H. E.; Li, X.; McGlynn, B. L.; Riveros-Iregui, D. A.; Emanuel, R. E.

    2017-08-01

    Terrestrial ecosystem responses to temperature and precipitation have major implications for the global carbon cycle. Case studies demonstrate that complex terrain, which accounts for more than 50% of Earth's land surface, can affect ecological processes associated with land-atmosphere carbon fluxes. However, no studies have addressed the role of complex terrain in mediating ecophysiological responses of land-atmosphere carbon fluxes to climate variables. We synthesized data from AmeriFlux towers and found that for sites in complex terrain, responses of ecosystem CO2 fluxes to temperature and precipitation are organized according to terrain slope and drainage area, variables associated with water and energy availability. Specifically, we found that for tower sites in complex terrain, mean topographic slope and drainage area surrounding the tower explained between 51% and 78% of site-to-site variation in the response of CO2 fluxes to temperature and precipitation depending on the time scale. We found no such organization among sites in flat terrain, even though their flux responses exhibited similar ranges. These results challenge prevailing conceptual framework in terrestrial ecosystem modeling that assumes that CO2 fluxes derive from vertical soil-plant-climate interactions. We conclude that the terrain in which ecosystems are situated can also have important influences on CO2 responses to temperature and precipitation. This work has implications for about 14% of the total land area of the conterminous U.S. This area is considered topographically complex and contributes to approximately 15% of gross ecosystem carbon production in the conterminous U.S.

  14. Vegetation greenness modelling in response to interannual precipitation and temperature changes between 2001 and 2012 in Liao River Basin in Jilin Province, China.

    Science.gov (United States)

    Lin, Xiao-Sheng; Tang, Jie; Li, Zhao-Yang; Li, Hai-Yi

    2016-01-01

    Liao River basin in Jilin Province is the place of origin of the Dongliao River. This study gives a comprehensive analysis of the vegetation coverage in the region and provides a potential theoretical basis for ecological restoration. The seasonal variation of vegetation greenness and dynamics based on the Normalized Difference Vegetation Index (NDVI) in major land cover types in the region was studied. Analyzing the relationship NDVI, temperature and rainfall, we derived a set of predictor variables from 2001 to 2012 using the MODIS Terra level 1 Product (MOD02QKM). The results showed a general increasing trend in NDVI value in the region, while 34.63 % of the region showed degradation. NDVI values begin to rise from April when plants are regreening and they drop in September when temperature are decreasing and the leaves are falling in the study area and temperature was found decreasing during the period of 2001-2012 while rainfall showed an increasing trend. This model could be used to observe the change in vegetation greenness and the dynamic effects of temperature and rainfall. This study provided important data for the environmental protection of the basin area. And we hope to provide scientific analysis for controlling water and soil erosion, maintaining the sustainable productivity of land resources, enhancing the treatment of water pollution and stimulating the virtuous cycle of the ecological system.

  15. Enhancing elevated temperature strength of copper containing aluminium alloys by forming L12 Al3Zr precipitates and nucleating θ″ precipitates on them.

    Science.gov (United States)

    Kumar Makineni, Surendra; Sugathan, Sandeep; Meher, Subhashish; Banerjee, Rajarshi; Bhattacharya, Saswata; Kumar, Subodh; Chattopadhyay, Kamanio

    2017-09-11

    Strengthening by precipitation of second phase is the guiding principle for the development of a host of high strength structural alloys, in particular, aluminium alloys for transportation sector. Higher efficiency and lower emission demands use of alloys at higher operating temperatures (200 °C-250 °C) and stresses, especially in applications for engine parts. Unfortunately, most of the precipitation hardened aluminium alloys that are currently available can withstand maximum temperatures ranging from 150-200 °C. This limit is set by the onset of the rapid coarsening of the precipitates and consequent loss of mechanical properties. In this communication, we present a new approach in designing an Al-based alloy through solid state precipitation route that provides a synergistic coupling of two different types of precipitates that has enabled us to develop coarsening resistant high-temperature alloys that are stable in the temperature range of 250-300 °C with strength in excess of 260 MPa at 250 °C.

  16. Changes in temperature and precipitation extremes observed in Modena, Italy

    Science.gov (United States)

    Boccolari, M.; Malmusi, S.

    2013-03-01

    Climate changes has become one of the most analysed subjects from researchers community, mainly because of the numerous extreme events that hit the globe. To have a better view of climate changes and trends, long observations time series are needed. During last decade a lot of Italian time series, concerning several surface meteorological variables, have been analysed and published. No one of them includes one of the longest record in Italy, the time series of the Geophysical Observatory of the University of Modena and Reggio Emilia. Measurements, collected since early 19th century, always in the same position, except for some months during the second world war, embrace daily temperature, precipitation amount, relative humidity, pressure, cloudiness and other variables. In this work we concentrated on the analysis of yearly and seasonal trends and climate extremes of temperature, both minimum and maximum, and precipitation time series, for the periods 1861-2010 and 1831-2010 respectively, in which continuous measurements are available. In general, our results confirm quite well those reported by IPCC and in many other studies over Mediterranean area. In particular, we found that minimum temperature has a non significant positive trend of + 0.1 °C per decade considering all the period, the value increases to 0.9 °C per decade for 1981-2010. For maximum temperature we observed a non significant + 0.1 °C trend for all the period, while + 0.8 °C for the last thirty years. On the other hand precipitation is decreasing, -6.3 mm per decade, considering all the analysed period, while the last thirty years are characterised by a great increment of 74.8 mm per decade. For both variables several climate indices have been analysed and they confirm what has been found for minimum and maximum temperatures and precipitation. In particular, during last 30 years frost days and ice days are decreasing, whereas summer days are increasing. During the last 30-year tropical nights

  17. MSU (Microwave Sounding Unit) Daily Troposphere Temperatures and Precipitation

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set consists of two MSU tropospheric temperatures levels and precipitation which are described in detail below. The NOAA satellites contributing to this...

  18. Time-temperature-sensitization and time-temperature-precipitation behavior of alloy 625

    International Nuclear Information System (INIS)

    Koehler, M.; Heubner, U.

    1996-01-01

    Time-Temperature-Sensitization diagrams have been established for a low-carbon version of alloy 625 (UNS N06625). Sensitization in terms of a 50 microm (2 mils) intergranular penetration criterion starts after about 3 h aging time at 750 C (soft annealed condition) or after less than 1 h aging time at 800 C (solution annealed condition) when tested according to ASTM-G 28 method A. Grain boundary precipitation of carbides occurs during aging of both the soft annealed and the solution annealed material, but the soft annealed material exhibits a more pronounced general precipitation of Ni 3 (Nb,Mo) phase giving rise to more distinct loss of ductility. Sensitization of alloy 625 may be retarded by lowering its iron content

  19. Compound effects of temperature and precipitation in making droughts more frequent in Marathwada, India

    Science.gov (United States)

    Mondal, A.; Zachariah, M.; Achutarao, K. M.; Otto, F. E. L.

    2017-12-01

    The Marathwada region in Maharashtra, India is known to suffer significantly from agrarian crisis including farmer suicides resulting from persistent droughts. Drought monitoring in India is commonly based on univariate indicators that consider the deficiency in precipitation alone. However, droughts may involve complex interplay of multiple physical variables, necessitating an integrated, multivariate approach to analyse their behaviour. In this study, we compare the behaviour of drought characteristics in Marathwada in the recent years as compared to the first half of the twentieth century, using a joint precipitation and temperature-based Multivariate Standardized Drought Index (MSDI). Drought events in the recent times are found to exhibit exceptional simultaneous anomalies of high temperature and precipitation deficits in this region, though studies on precipitation alone show that these events are within the range of historically observed variability. Additionally, we also develop multivariate copula-based Severity-Duration-Frequency (SDF) relationships for droughts in this region and compare their natures pre- and post- 1950. Based on multivariate return periods considering both temperature and precipitation anomalies, as well as the severity and duration of droughts, it is found that droughts have become more frequent in the post-1950 period. Based on precipitation alone, such an observation cannot be made. This emphasizes the sensitivity of droughts to temperature and underlines the importance of considering compound effects of temperature and precipitation in order to avoid an underestimation of drought risk. This observation-based analysis is the first step towards investigating the causal mechanisms of droughts, their evolutions and impacts in this region, particularly those influenced by anthropogenic climate change.

  20. Linking increases in hourly precipitation extremes to atmospheric temperature and moisture changes

    International Nuclear Information System (INIS)

    Lenderink, Geert; Van Meijgaard, Erik

    2010-01-01

    Relations between hourly precipitation extremes and atmospheric temperature and moisture derived for the present-day climate are studied with the aim of understanding the behavior (and the uncertainty in predictions) of hourly precipitation extremes in a changing climate. A dependency of hourly precipitation extremes on the daily mean 2 m temperature of approximately two times the Clausius-Clapeyron (CC) relation is found for temperatures above 10 deg. C. This is a robust relation obtained in four observational records across western Europe. A dependency following the CC relation can be explained by the observed increase in atmospheric (absolute) humidity with temperature, whereas the enhanced dependency (compared to the CC relation) appears to be caused by dynamical feedbacks owing to excess latent heat release in extreme showers. Integrations with the KNMI regional climate model RACMO2 at 25 km grid spacing show that changes in hourly precipitation extremes may indeed considerably exceed the prediction from the CC relation. The results suggests that increases of + 70% or even more are possible by the end of this century. However, a different regional model (CLM operated at ETHZ) predicts much smaller increases; this is probably caused by a too strong sensitivity of this model to a decrease in relative humidity.

  1. Energetic consequences of field body temperatures in the green iguana

    NARCIS (Netherlands)

    Lichtenbelt, WDVM; Wesselingh, RA

    We investigated body temperatures of free-ranging green iguanas (Iguana iguana) on Curacao (Netherlands Antilles), and how metabolic costs and benefits of food processing affect body temperatures. Body temperatures of free-living iguanas were measured by radio telemetry. We also used a model, with

  2. Gridded 5km GHCN-Daily Temperature and Precipitation Dataset, Version 1

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Gridded 5km GHCN-Daily Temperature and Precipitation Dataset (nClimGrid) consists of four climate variables derived from the GHCN-D dataset: maximum temperature,...

  3. The influence of precipitation temperature on the properties of ceria–zirconia solid solution composites

    International Nuclear Information System (INIS)

    Cui, Yajuan; Fang, Ruimei; Shang, Hongyan; Shi, Zhonghua; Gong, Maochu; Chen, Yaoqiang

    2015-01-01

    Highlights: • The crystallite size of precipitate increases as the precipitation temperature rises. • The stack of large crystallite can form nanoparticles with big pore size. • Big pore sizes are advantageous to improve the thermal stability. • Phase segregation is restricted in CZ solid solution precipitated at 70 °C. • The reducibility and OSC of the solid solution precipitated at 70 °C are improved. - Abstract: The ceria–zirconia composites (CZ) with a Ce/Zr mass ratio of 1/1 were synthesized by a back-titration method, in which the influence of precipitation temperature on the properties of ceria–zirconia precipitates was investigated. The resulting precipitation and mixed oxides at different precipitation temperatures were then characterized by a range of techniques, including textural properties, X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), H 2 -temperature programmed reduction (H 2 -TPR) as well as oxygen storage capacity (OSC) measurement. The results revealed that ceria–zirconia composites were formed as solid solution and such structure is favored of thermostability and texture properties. In particular, the composite CZ-70 synthesized at 70 °C exhibited prominent thermostability with a surface area of 32 m 2 /g as well as a pore volume of 0.15 cc/g after aging treatment at 1000 °C for 5 h. And this was found to be associated with the wider pore size distribution which maybe owed to the formation of large crystal at the primary stage of precipitation. Additionally, the composite CZ-70 showed excellent reduction property and OSC benefiting from stable texture and structure

  4. Joint distribution of temperature and precipitation in the Mediterranean, using the Copula method

    Science.gov (United States)

    Lazoglou, Georgia; Anagnostopoulou, Christina

    2018-03-01

    This study analyses the temperature and precipitation dependence among stations in the Mediterranean. The first station group is located in the eastern Mediterranean (EM) and includes two stations, Athens and Thessaloniki, while the western (WM) one includes Malaga and Barcelona. The data was organized in two time periods, the hot-dry period and the cold-wet one, composed of 5 months, respectively. The analysis is based on a new statistical technique in climatology: the Copula method. Firstly, the calculation of the Kendall tau correlation index showed that temperatures among stations are dependant during both time periods whereas precipitation presents dependency only between the stations located in EM or WM and only during the cold-wet period. Accordingly, the marginal distributions were calculated for each studied station, as they are further used by the copula method. Finally, several copula families, both Archimedean and Elliptical, were tested in order to choose the most appropriate one to model the relation of the studied data sets. Consequently, this study achieves to model the dependence of the main climate parameters (temperature and precipitation) with the Copula method. The Frank copula was identified as the best family to describe the joint distribution of temperature, for the majority of station groups. For precipitation, the best copula families are BB1 and Survival Gumbel. Using the probability distribution diagrams, the probability of a combination of temperature and precipitation values between stations is estimated.

  5. Temperature-dependent daily variability of precipitable water in special sensor microwave/imager observations

    Science.gov (United States)

    Gutowski, William J.; Lindemulder, Elizabeth A.; Jovaag, Kari

    1995-01-01

    We use retrievals of atmospheric precipitable water from satellite microwave observations and analyses of near-surface temperature to examine the relationship between these two fields on daily and longer time scales. The retrieval technique producing the data used here is most effective over the open ocean, so the analysis focuses on the southern hemisphere's extratropics, which have an extensive ocean surface. For both the total and the eddy precipitable water fields, there is a close correspondence between local variations in the precipitable water and near-surface temperature. The correspondence appears particularly strong for synoptic and planetary scale transient eddies. More specifically, the results support a typical modeling assumption that transient eddy moisture fields are proportional to transient eddy temperature fields under the assumption f constant relative humidity.

  6. Mechanical Properties of Discontinuous Precipitated Al-Zn Alloys after Drawing at Room and Cryogenic Temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Min Soo; Lee, Jehyun [Changwon National University, Changwon (Korea, Republic of); Han, Seung Zeon; Ahn, Jee Hyuk [Korea Institute of Materials Science, Changwon (Korea, Republic of); Lim, Sung Hwan [Kangwon National University, Chuncheon (Korea, Republic of); Kim, Kwang Ho [Pusan National University, Pusan (Korea, Republic of); Kim, Sang sik [Gyeongsang National University, Jinju (Korea, Republic of)

    2017-02-15

    In order to study the effect of microstructural change on the tensile properties of discontinuous precipitated Al-Zn binary alloy, four different Al-Zn alloys(25, 30, 35, 45 wt%Zn) were aged at 160 ℃ for different aging times(0, 5, 15, 30, 60, 120, 360 min) after being solution treated at 400 ℃, and successively drawn at room and cryogenic temperatures(-197 ℃). Discontinuous precipitation was formed during aging in the Al matrix(which contained more than 30 wt%Zn) in Al alloys containing more than 30 wt%Zn. The tensile strength of continuous precipitated Al-35Zn alloy decreased with increasing drawing ratio, however, the tensile strength of discontinuous precipitated Al-35Zn alloy increased with further drawing. The strength and ductility combination, 350 MPa-36%was achieved by drawning discontinuous precipitated Al-Zn alloy at room temperature. The discontinuous precipitated Al-Zn alloy drawn at cryogenic temperature showed a higher value of tensile strength, over 500 MPa, although ductility decreased.

  7. Mechanical Properties of Discontinuous Precipitated Al-Zn Alloys after Drawing at Room and Cryogenic Temperatures

    International Nuclear Information System (INIS)

    Kim, Min Soo; Lee, Jehyun; Han, Seung Zeon; Ahn, Jee Hyuk; Lim, Sung Hwan; Kim, Kwang Ho; Kim, Sang sik

    2017-01-01

    In order to study the effect of microstructural change on the tensile properties of discontinuous precipitated Al-Zn binary alloy, four different Al-Zn alloys(25, 30, 35, 45 wt%Zn) were aged at 160 ℃ for different aging times(0, 5, 15, 30, 60, 120, 360 min) after being solution treated at 400 ℃, and successively drawn at room and cryogenic temperatures(-197 ℃). Discontinuous precipitation was formed during aging in the Al matrix(which contained more than 30 wt%Zn) in Al alloys containing more than 30 wt%Zn. The tensile strength of continuous precipitated Al-35Zn alloy decreased with increasing drawing ratio, however, the tensile strength of discontinuous precipitated Al-35Zn alloy increased with further drawing. The strength and ductility combination, 350 MPa-36%was achieved by drawning discontinuous precipitated Al-Zn alloy at room temperature. The discontinuous precipitated Al-Zn alloy drawn at cryogenic temperature showed a higher value of tensile strength, over 500 MPa, although ductility decreased.

  8. Scaling of precipitation extremes with temperature in the French Mediterranean region: What explains the hook shape?

    Science.gov (United States)

    Drobinski, P.; Alonzo, B.; Bastin, S.; Silva, N. Da; Muller, C.

    2016-04-01

    Expected changes to future extreme precipitation remain a key uncertainty associated with anthropogenic climate change. Extreme precipitation has been proposed to scale with the precipitable water content in the atmosphere. Assuming constant relative humidity, this implies an increase of precipitation extremes at a rate of about 7% °C-1 globally as indicated by the Clausius-Clapeyron relationship. Increases faster and slower than Clausius-Clapeyron have also been reported. In this work, we examine the scaling between precipitation extremes and temperature in the present climate using simulations and measurements from surface weather stations collected in the frame of the HyMeX and MED-CORDEX programs in Southern France. Of particular interest are departures from the Clausius-Clapeyron thermodynamic expectation, their spatial and temporal distribution, and their origin. Looking at the scaling of precipitation extreme with temperature, two regimes emerge which form a hook shape: one at low temperatures (cooler than around 15°C) with rates of increase close to the Clausius-Clapeyron rate and one at high temperatures (warmer than about 15°C) with sub-Clausius-Clapeyron rates and most often negative rates. On average, the region of focus does not seem to exhibit super Clausius-Clapeyron behavior except at some stations, in contrast to earlier studies. Many factors can contribute to departure from Clausius-Clapeyron scaling: time and spatial averaging, choice of scaling temperature (surface versus condensation level), and precipitation efficiency and vertical velocity in updrafts that are not necessarily constant with temperature. But most importantly, the dynamical contribution of orography to precipitation in the fall over this area during the so-called "Cevenoles" events, explains the hook shape of the scaling of precipitation extremes.

  9. Soil temperature and precipitation affect the rooting ability of dormant hardwood cuttings of Populus

    Science.gov (United States)

    R.S., Jr. Zalesny; R.B. Hall; E.O. Bauer; D.E. Riemenschneider

    2005-01-01

    In addition to genetic control, responses to environmental stimuli affect the success of rooting. Our objectives were to: 1) assess the variation in rooting ability among 21 Populus clones grown under varying soil temperatures and amounts of precipitation and 2) identify combinations of soil temperature and precipitation that promote rooting. The...

  10. Changes of the Temperature and Precipitation Extremes on Homogenized Data

    Directory of Open Access Journals (Sweden)

    LAKATOS, Mónika

    2007-01-01

    Full Text Available Climate indices to detect changes have been defined in several international projects onclimate change. Climate index calculations require at least daily resolution of time series withoutinhomogeneities, such as transfer of stations, changes in observation practice. In many cases thecharacteristics of the estimated linear trends, calculated from the original and from the homogenizedtime series are significantly different. The ECA&D (European Climate Assessment & Dataset indicesand some other special temperature and precipitation indices of own development were applied to theClimate Database of the Hungarian Meteorological Service. Long term daily maximum, minimum anddaily mean temperature data series and daily precipitation sums were examined. The climate indexcalculation processes were tested on original observations and on homogenized daily data fortemperature; in the case of precipitation a complementation process was performed to fill in the gapsof missing data. Experiences of comparing the climate index calculation results, based on original andcomplemented-homogenized data, are reported in this paper. We present the preliminary result ofclimate index calculations also on gridded (interpolated daily data.

  11. Central Asia Temperature and Precipitation Data, 1879-2003, Version 1

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides temperature and precipitation data from 298 meteorological stations in the Northern Tien Shan and Pamir Mountain Ranges of Central Asia,...

  12. Strong impacts of daily minimum temperature on the green-up date and summer greenness of the Tibetan Plateau.

    Science.gov (United States)

    Shen, Miaogen; Piao, Shilong; Chen, Xiaoqiu; An, Shuai; Fu, Yongshuo H; Wang, Shiping; Cong, Nan; Janssens, Ivan A

    2016-09-01

    Understanding vegetation responses to climate change on the Tibetan Plateau (TP) helps in elucidating the land-atmosphere energy exchange, which affects air mass movement over and around the TP. Although the TP is one of the world's most sensitive regions in terms of climatic warming, little is known about how the vegetation responds. Here, we focus on how spring phenology and summertime greenness respond to the asymmetric warming, that is, stronger warming during nighttime than during daytime. Using both in situ and satellite observations, we found that vegetation green-up date showed a stronger negative partial correlation with daily minimum temperature (Tmin ) than with maximum temperature (Tmax ) before the growing season ('preseason' henceforth). Summer vegetation greenness was strongly positively correlated with summer Tmin , but negatively with Tmax . A 1-K increase in preseason Tmin advanced green-up date by 4 days (P greenness by 3.6% relative to the mean greenness during 2000-2004 (P green-up date (P > 0.10) and higher summer Tmax even reduced greenness by 2.6% K(-1) (P greenness were probably due to the accompanying decline in water availability. The dominant enhancing effect of nighttime warming indicates that climatic warming will probably have stronger impact on TP ecosystems than on apparently similar Arctic ecosystems where vegetation is controlled mainly by Tmax . Our results are crucial for future improvements of dynamic vegetation models embedded in the Earth System Models which are being used to describe the behavior of the Asian monsoon. The results are significant because the state of the vegetation on the TP plays an important role in steering the monsoon. © 2016 John Wiley & Sons Ltd.

  13. TEM Study of High-Temperature Precipitation of Delta Phase in Inconel 718 Alloy

    Directory of Open Access Journals (Sweden)

    Moukrane Dehmas

    2011-01-01

    Full Text Available Inconel 718 is widely used because of its ability to retain strength at up to 650∘C for long periods of time through coherent metastable  Ni3Nb precipitation associated with a smaller volume fraction of  Ni3Al precipitates. At very long ageing times at service temperature,  decomposes to the stable Ni3Nb phase. This latter phase is also present above the  solvus and is used for grain control during forging of alloy 718. While most works available on precipitation have been performed at temperatures below the  solvus, it appeared of interest to also investigate the case where phase precipitates directly from the fcc matrix free of  precipitates. This was studied by X-ray diffraction and transmission electron microscopy (TEM. TEM observations confirmed the presence of rotation-ordered domains in plates, and some unexpected contrast could be explained by double diffraction due to overlapping phases.

  14. Increased Kawasaki Disease Incidence Associated With Higher Precipitation and Lower Temperatures, Japan, 1991-2004.

    Science.gov (United States)

    Abrams, Joseph Y; Blase, Jennifer L; Belay, Ermias D; Uehara, Ritei; Maddox, Ryan A; Schonberger, Lawrence B; Nakamura, Yosikazu

    2018-06-01

    Kawasaki disease (KD) is an acute febrile vasculitis, which primarily affects children. The etiology of KD is unknown; while certain characteristics of the disease suggest an infectious origin, genetic or environmental factors may also be important. Seasonal patterns of KD incidence are well documented, but it is unclear whether these patterns are caused by changes in climate or by other unknown seasonal effects. The relationship between KD incidence and deviations from expected temperature and precipitation were analyzed using KD incidence data from Japanese nationwide epidemiologic surveys (1991-2004) and climate data from 136 weather stations of the Japan Meteorological Agency. Seven separate Poisson-distributed generalized linear regression models were run to examine the effects of temperature and precipitation on KD incidence in the same month as KD onset and the previous 1, 2, 3, 4, 5 and 6 months, controlling for geography as well as seasonal and long-term trends in KD incidence. KD incidence was negatively associated with temperature in the previous 2, 3, 4 and 5 months and positively associated with precipitation in the previous 1 and 2 months. The model that best predicted variations in KD incidence used climate data from the previous 2 months. An increase in total monthly precipitation by 100 mm was associated with increased KD incidence (rate ratio [RR] 1.012, 95% confidence interval [CI]: 1.005-1.019), and an increase of monthly mean temperature by 1°C was associated with decreased KD incidence (RR 0.984, 95% CI: 0.978-0.990). KD incidence was significantly affected by temperature and precipitation in previous months independent of other unknown seasonal factors. Climate data from the previous 2 months best predicted the variations in KD incidence. Although fairly minor, the effect of temperature and precipitation independent of season may provide additional clues to the etiology of KD.

  15. Data set: 31 years of spatially distributed air temperature, humidity, precipitation amount and precipitation phase from a mountain catchment in the rain-snow transition zone

    Science.gov (United States)

    Thirty one years of spatially distributed air temperature, relative humidity, dew point temperature, precipitation amount, and precipitation phase data are presented for the Reynolds Creek Experimental Watershed. The data are spatially distributed over a 10m Lidar-derived digital elevation model at ...

  16. A space and time scale-dependent nonlinear geostatistical approach for downscaling daily precipitation and temperature

    KAUST Repository

    Jha, Sanjeev Kumar

    2015-07-21

    A geostatistical framework is proposed to downscale daily precipitation and temperature. The methodology is based on multiple-point geostatistics (MPS), where a multivariate training image is used to represent the spatial relationship between daily precipitation and daily temperature over several years. Here, the training image consists of daily rainfall and temperature outputs from the Weather Research and Forecasting (WRF) model at 50 km and 10 km resolution for a twenty year period ranging from 1985 to 2004. The data are used to predict downscaled climate variables for the year 2005. The result, for each downscaled pixel, is daily time series of precipitation and temperature that are spatially dependent. Comparison of predicted precipitation and temperature against a reference dataset indicates that both the seasonal average climate response together with the temporal variability are well reproduced. The explicit inclusion of time dependence is explored by considering the climate properties of the previous day as an additional variable. Comparison of simulations with and without inclusion of time dependence shows that the temporal dependence only slightly improves the daily prediction because the temporal variability is already well represented in the conditioning data. Overall, the study shows that the multiple-point geostatistics approach is an efficient tool to be used for statistical downscaling to obtain local scale estimates of precipitation and temperature from General Circulation Models. This article is protected by copyright. All rights reserved.

  17. The nonstationary impact of local temperature changes and ENSO on extreme precipitation at the global scale

    Science.gov (United States)

    Sun, Qiaohong; Miao, Chiyuan; Qiao, Yuanyuan; Duan, Qingyun

    2017-12-01

    The El Niño-Southern Oscillation (ENSO) and local temperature are important drivers of extreme precipitation. Understanding the impact of ENSO and temperature on the risk of extreme precipitation over global land will provide a foundation for risk assessment and climate-adaptive design of infrastructure in a changing climate. In this study, nonstationary generalized extreme value distributions were used to model extreme precipitation over global land for the period 1979-2015, with ENSO indicator and temperature as covariates. Risk factors were estimated to quantify the contrast between the influence of different ENSO phases and temperature. The results show that extreme precipitation is dominated by ENSO over 22% of global land and by temperature over 26% of global land. With a warming climate, the risk of high-intensity daily extreme precipitation increases at high latitudes but decreases in tropical regions. For ENSO, large parts of North America, southern South America, and southeastern and northeastern China are shown to suffer greater risk in El Niño years, with more than double the chance of intense extreme precipitation in El Niño years compared with La Niña years. Moreover, regions with more intense precipitation are more sensitive to ENSO. Global climate models were used to investigate the changing relationship between extreme precipitation and the covariates. The risk of extreme, high-intensity precipitation increases across high latitudes of the Northern Hemisphere but decreases in middle and lower latitudes under a warming climate scenario, and will likely trigger increases in severe flooding and droughts across the globe. However, there is some uncertainties associated with the influence of ENSO on predictions of future extreme precipitation, with the spatial extent and risk varying among the different models.

  18. Effect of austenite deformation temperature on Nb clustering and precipitation in microalloyed steel

    International Nuclear Information System (INIS)

    Pereloma, E.V.; Kostryzhev, A.G.; AlShahrani, A.; Zhu, C.; Cairney, J.M.; Killmore, C.R.; Ringer, S.P.

    2014-01-01

    The effect of thermomechanical processing conditions on Nb clustering and precipitation in both austenite and ferrite in a Nb–Ti microalloyed steel was studied using electron microscopy and atom probe tomography. A decrease in the deformation temperature increased the Nb-rich precipitation in austenite and decreased the extent of precipitation in ferrite. Microstructural mechanisms that explain this variation are discussed

  19. Spatial Variation of Temperature and Precipitation in Bhutan and Links to Vegetation and Land Cover

    Directory of Open Access Journals (Sweden)

    Ugyen Dorji

    2016-02-01

    Full Text Available Bhutan, located in the Himalayas in the South Asian monsoon region, has extremely high variation in elevation, climatic conditions, and land cover despite its small geographical area, as well as great biodiversity. This paper provides the first comprehensive description of climatic conditions in Bhutan. It assesses the spatial variation of temperature and precipitation across the country and evaluates the causes for this variation based on daily data from 70 meteorological stations that have been recording data for time spans ranging from 3 to 21 years. Temperature and precipitation show contrasting spatial variation, with temperature primarily affected by elevation and precipitation by latitude. Models were developed using mixed linear regression models to predict seasonal and annual mean temperature and precipitation based on geographical location. Using linear regression we found that temperatures changed by about 0.5°C for every 100 m of change in elevation, with lapse rates being highest in February, March, and November and lowest from June to August. The lapse rate was highest for minimum temperatures and lowest for maximum temperatures, with the greatest difference during winter. The spatial distribution of precipitation was mainly controlled by latitude, having a quadratic relationship, with the highest rates in the southern foothills of the Himalayan range and the lowest at midlatitudes. The land cover is affected by topography and local climate, with variations in temperature being a main deciding factor for vegetation types; most human settlements and associated land uses are concentrated at lower elevations.

  20. Spatial interpolation of hourly precipitation and dew point temperature for the identification of precipitation phase and hydrologic response in a mountainous catchment

    Science.gov (United States)

    Garen, D. C.; Kahl, A.; Marks, D. G.; Winstral, A. H.

    2012-12-01

    In mountainous catchments, it is well known that meteorological inputs, such as precipitation, air temperature, humidity, etc. vary greatly with elevation, spatial location, and time. Understanding and monitoring catchment inputs is necessary in characterizing and predicting hydrologic response to these inputs. This is true all of the time, but it is the most dramatically critical during large storms, when the input to the stream system due to rain and snowmelt creates the potential for flooding. Besides such crisis events, however, proper estimation of catchment inputs and their spatial distribution is also needed in more prosaic but no less important water and related resource management activities. The first objective of this study is to apply a geostatistical spatial interpolation technique (elevationally detrended kriging) to precipitation and dew point temperature on an hourly basis and explore its characteristics, accuracy, and other issues. The second objective is to use these spatial fields to determine precipitation phase (rain or snow) during a large, dynamic winter storm. The catchment studied is the data-rich Reynolds Creek Experimental Watershed near Boise, Idaho. As part of this analysis, precipitation-elevation lapse rates are examined for spatial and temporal consistency. A clear dependence of lapse rate on precipitation amount exists. Certain stations, however, are outliers from these relationships, showing that significant local effects can be present and raising the question of whether such stations should be used for spatial interpolation. Experiments with selecting subsets of stations demonstrate the importance of elevation range and spatial placement on the interpolated fields. Hourly spatial fields of precipitation and dew point temperature are used to distinguish precipitation phase during a large rain-on-snow storm in December 2005. This application demonstrates the feasibility of producing hourly spatial fields and the importance of doing

  1. Effects of altered temperature and precipitation on desert protozoa associated with biological soil crusts.

    Science.gov (United States)

    Darby, Brian J; Housman, David C; Zaki, Amr M; Shamout, Yassein; Adl, Sina M; Belnap, Jayne; Neher, Deborah A

    2006-01-01

    Biological soil crusts are diverse assemblages of bacteria, cyanobacteria, algae, fungi, lichens, and mosses that cover much of arid land soils. The objective of this study was to quantify protozoa associated with biological soil crusts and test the response of protozoa to increased temperature and precipitation as is predicted by some global climate models. Protozoa were more abundant when associated with cyanobacteria/lichen crusts than with cyanobacteria crusts alone. Amoebae, flagellates, and ciliates originating from the Colorado Plateau desert (cool desert, primarily winter precipitation) declined 50-, 10-, and 100-fold, respectively, when moved in field mesocosms to the Chihuahuan Desert (hot desert, primarily summer rain). However, this was not observed in protozoa collected from the Chihuahuan Desert and moved to the Sonoran desert (hot desert, also summer rain, but warmer than Chihuahuan Desert). Protozoa in culture began to encyst at 37 degrees C. Cysts survived the upper end of daily temperatures (37-55 degrees C), and could be stimulated to excyst if temperatures were reduced to 15 degrees C or lower. Results from this study suggest that cool desert protozoa are influenced negatively by increased summer precipitation during excessive summer temperatures, and that desert protozoa may be adapted to a specific desert's temperature and precipitation regime.

  2. Fuel properties and precipitate formation at low temperature in soy-, cottonseed-, and poultry fat-based biodiesel blends

    Energy Technology Data Exchange (ETDEWEB)

    Haiying Tang; Steven O. Salley; K.Y. Simon Ng [Wayne State University, Detroit, MI (United States). Department of Chemical Engineering and Materials Science

    2008-10-15

    The formation of precipitates in biodiesel blends may have serious implications for diesel engine fuel delivery systems. Precipitates were observed in Soybean oil (SBO-), cottonseed oil (CSO-), and poultry fat (PF-) based biodiesel blends after storage at 4{sup o}C. CSO- and PF-based biodiesel had a lower mass of precipitates observed than the SBO-based. Moreover, different rates of precipitate formation were observed for the B20 versus the B100. These suggested that the formation of precipitate during cold temperature storage was dependent on the feedstock and blend concentration. The solvency effects of biodiesel blends were more pronounced at low temperature than at room temperature leading to a higher amount of precipitates formed. Fourier transform infrared (FTIR) spectra, and gas chromatography-flame ionization detector (GC-FID) chromatograms indicated that steryl glucosides are the major cause of precipitate formation in SBO-based biodiesel; while for PF-based biodiesel, the precipitates are due to mono-glycerides. However, the precipitates from CSO-based biodiesel are due to both steryl glucosides and mono-glycerides. 45 refs., 11 figs., 2 tabs.

  3. Relationships between δ18O in summer precipitation and temperature and moisture trajectories at Muztagata, western China

    Institute of Scientific and Technical Information of China (English)

    YU; Wusheng; YAO; Tandong; TIAN; Lide; LI; Zhen; SUN; Weizhen; WANG; Yu

    2006-01-01

    Based on summer observations of stable isotope of precipitation at Muztagata, western China, during 2002―2003, this paper presents the relationship between δ18O in precipitation and air temperature, and discusses the effect of moisture transport on δ18O in precipitation. Results show that air temperature correlates positively with δ18O in precipitation, and the temperature effect controls the δ18O of precipitation in this area. The Muztagata region exhibits high δ18O values in summer precipitation, similar to those shown at stations in adjacent regions. According to the results of our model set up to trace the moisture trajectories, the westerlies and local moisture circulation contribute to variations of oxygen isotopes in precipitation. In addition, the impacts of the moisture transport distance, the moisture transport level, and the incursion of the polar air mass also influence the variations of δ18O in precipitation. The moisture origins and transport mechanisms also contribute to the variation of δ18O in precipitation at Muztagata.

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

    Science.gov (United States)

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

    2018-04-01

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

  5. Correlation between δ18O in precipitation and surface air temperature on different time-scale in China

    International Nuclear Information System (INIS)

    Zhang Lin; Chen Zongyu; Nie Zhenlong; Liu Fuliang; Jia Yankun; Zhang Xiangyang

    2008-01-01

    The relation between isotopic compositions of precipitation and surface air temperature provides a unique tool for paleoclimate studies, among which the relation between long term changes in δ 18 O of precipitation and surface air temperature at different stations or in a given location seems to be the most appropriate to paleoclimatic reconstructions. Analysis was conducted on monthly and annual mean δ 18 O content of precipitation and surface air temperature at spatial and fixed locations by using the data of China (1985-2002) in Global Network of Isotopes in Precipitation (GNIP) Database. This study shows that there is a positive correlation between δ 18 O of precipitation and surface air temperature for stations located in north of 34 degree-36 degree N latitudes. The seasonal δ 18 O-temperature gradient derived from the monthly data of 12 stations in northern China is about 0.034% degree C -1 . The δ 18 O-temperature gradient, however, derived from the long term annual mean data of 13 stations, is about 0.052% degree C -1 , which is substantially larger than the seasonal gradient. (authors)

  6. Comparison of structural and luminescence properties of Dy2O3 nanopowders synthesized by co-precipitation and green combustion routes

    International Nuclear Information System (INIS)

    Chandrasekhar, M.; Nagabhushana, H.; Sudheerkumar, K.H.; Dhananjaya, N.; Sharma, S.C.; Kavyashree, D.; Shivakumara, C.; Nagabhushana, B.M.

    2014-01-01

    Highlights: • Dy 2 O 3 nanopowders were prepared by co-precipitation and eco-friendly green combustion route using plant latex. • Both the products show excellent chromaticity coordinates in the white region, which were quite useful for white LED’s. • Thermoluminescence response of the Dy 2 O 3 product prepared by green synthesis was higher when compared to co-precipitation route. • Structural parameters of Dy 2 O 3 were estimated using Rietveld refinement. • The development of nanosize materials using eco-friendly resources was an attractive non-hazardous chemical route. - Abstract: Dysprosium oxide (Dy 2 O 3 ) nanopowders were prepared by co-precipitation (CP) and eco-friendly green combustion (GC) routes. SEM micrographs prepared by CP route show smooth rods with various lengths and diameters while, GC route show porous, agglomerated particles. The results were further confirmed by TEM. Thermoluminescence (TL) responses of the nanopowder prepared by both the routes were studied using γ-rays. A well resolved glow peak at 353 °C along with less intense peak at 183 °C was observed in GC route while, in CP a single glow peak at 364 °C was observed. The kinetic parameters were estimated using Chen’s glow peak route. Photoluminescence (PL) of Dy 2 O 3 shows peaks at 481, 577, 666 and 756 nm which were attributed to Dy 3+ transitions of 4 F 9/2 ⟶ 6 H 15/2 , 6 H 13/2 , 6 H 11/2 and 6 H 9/2 , respectively. Color co-ordinate values were located in the white region as a result the product may be useful for the fabrication of WLED’S

  7. Assessing homogeneity and climate variability of temperature and precipitation series in the capitals of northeastern Brazil

    Science.gov (United States)

    Hänsel, Stephanie; Medeiros, Deusdedit; Matschullat, Jörg; Silva, Isamara; Petta, Reinaldo

    2016-03-01

    A 51-year dataset (1961 to 2011) from nine meteorological stations in the capitals of northeastern Brazil (NEB), with daily data of precipitation totals and of mean, minimum and maximum temperatures, was statistically analyzed for data homogeneity and for signals of climate variability. The hypothesis was explored that a connection exists between inhomogeneities of the time series and the meteorological systems influencing the region. Results of the homogeneity analysis depend on the selected test variable, the test algorithm and the chosen significance level; all more or less subjective choices. Most of the temperature series was classified as "suspect", while most of the precipitation series was categorized as "useful". Displaying and visually checking the time series demonstrates the power of expertise and may allow for a deeper data analysis. Consistent changes in the seasonality of temperature and precipitation emerge over NEB despite manifold breaks in the temperature series. Both series appear to be coupled. The intra-annual temperature and precipitation ranges have increased, along with an intensified seasonal cycle. Temperature mainly increased during DJF, MAM and SON, with decreases in JJA being related to wetter conditions and more frequent heavy precipitation events. Drought conditions mostly increased in SON and DJF, depending on the timing of the local dry season.

  8. Discriminating the precipitation phase based on different temperature thresholds in the Songhua River Basin, China

    Science.gov (United States)

    Zhong, Keyuan; Zheng, Fenli; Xu, Ximeng; Qin, Chao

    2018-06-01

    Different precipitation phases (rain, snow or sleet) differ greatly in their hydrological and erosional processes. Therefore, accurate discrimination of the precipitation phase is highly important when researching hydrologic processes and climate change at high latitudes and mountainous regions. The objective of this study was to identify suitable temperature thresholds for discriminating the precipitation phase in the Songhua River Basin (SRB) based on 20-year daily precipitation collected from 60 meteorological stations located in and around the basin. Two methods, the air temperature method (AT method) and the wet bulb temperature method (WBT method), were used to discriminate the precipitation phase. Thirteen temperature thresholds were used to discriminate snowfall in the SRB. These thresholds included air temperatures from 0 to 5.5 °C at intervals of 0.5 °C and the wet bulb temperature (WBT). Three evaluation indices, the error percentage of discriminated snowfall days (Ep), the relative error of discriminated snowfall (Re) and the determination coefficient (R2), were applied to assess the discrimination accuracy. The results showed that 2.5 °C was the optimum threshold temperature for discriminating snowfall at the scale of the entire basin. Due to differences in the landscape conditions at the different stations, the optimum threshold varied by station. The optimal threshold ranged 1.5-4.0 °C, and 19 stations, 17 stations and 18 stations had optimal thresholds of 2.5 °C, 3.0 °C, and 3.5 °C respectively, occupying 90% of all stations. Compared with using a single suitable temperature threshold to discriminate snowfall throughout the basin, it was more accurate to use the optimum threshold at each station to estimate snowfall in the basin. In addition, snowfall was underestimated when the temperature threshold was the WBT and when the temperature threshold was below 2.5 °C, whereas snowfall was overestimated when the temperature threshold exceeded 4

  9. Sensitivity of extreme precipitation to temperature: the variability of scaling factors from a regional to local perspective

    Science.gov (United States)

    Schroeer, K.; Kirchengast, G.

    2018-06-01

    Potential increases in extreme rainfall induced hazards in a warming climate have motivated studies to link precipitation intensities to temperature. Increases exceeding the Clausius-Clapeyron (CC) rate of 6-7%/°C-1 are seen in short-duration, convective, high-percentile rainfall at mid latitudes, but the rates of change cease or revert at regionally variable threshold temperatures due to moisture limitations. It is unclear, however, what these findings mean in term of the actual risk of extreme precipitation on a regional to local scale. When conditioning precipitation intensities on local temperatures, key influences on the scaling relationship such as from the annual cycle and regional weather patterns need better understanding. Here we analyze these influences, using sub-hourly to daily precipitation data from a dense network of 189 stations in south-eastern Austria. We find that the temperature sensitivities in the mountainous western region are lower than in the eastern lowlands. This is due to the different weather patterns that cause extreme precipitation in these regions. Sub-hourly and hourly intensities intensify at super-CC and CC-rates, respectively, up to temperatures of about 17 °C. However, we also find that, because of the regional and seasonal variability of the precipitation intensities, a smaller scaling factor can imply a larger absolute change in intensity. Our insights underline that temperature precipitation scaling requires careful interpretation of the intent and setting of the study. When this is considered, conditional scaling factors can help to better understand which influences control the intensification of rainfall with temperature on a regional scale.

  10. Green Compact Temperature Evolution during Current-Activated Tip-Based Sintering (CATS of Nickel

    Directory of Open Access Journals (Sweden)

    Khaled Morsi

    2013-04-01

    Full Text Available Current-activated tip-based sintering (CATS is a novel process where spark plasma sintering conditions are applied through an electrically conducting tip on a locally controlled area on a green powder compact/bed. The localization of electric current in CATS allows for unique temporal and spatial current and temperature distributions within the tip and powder compact. In this paper, special experimental setups were used to monitor the temperature profiles in the tip and at multiple locations on the surface of nickel powder compacts. A variation in the initial green density was found to have a significant effect on the maximum temperature in the tip as well as the temperature distribution across the powder compact. In general, the lowest green density specimens displayed the best conditions for localized densification. The concept of effective current density is introduced and results are discussed in relation to the densification parameter.

  11. Purification and low temperature spectroscopy of gecko visual pigments green and blue.

    Science.gov (United States)

    Kojima, D; Imai, H; Okano, T; Fukada, Y; Crescitelli, F; Yoshizawa, T; Shichida, Y

    1995-01-24

    We purified two kinds of visual pigments, gecko green and gecko blue, from retinas of Tokay geckos (Gekko gekko) by two steps of column chromatography, and investigated their photobleaching processes by means of low temperature spectroscopy. Absorption maxima of gecko green and blue solubilized in a mixture of 3-[(3-cholamidopropyl)dimethylammonio]-1- propanesulfonate (CHAPS) and phosphatidylcholine were 522 and 465 nm, respectively, which are close to those observed in the photoreceptor cells. Low temperature spectroscopy identified six intermediates in the photobleaching process of gecko green; batho (lambda max = 569 nm), BL (lambda max = 519 nm), lumi (507 nm), meta I (approximately 486 nm), meta II (approximately 384 nm), and meta III intermediates (approximately 500 nm). In contrast to the high similarity in amino acid sequence between gecko green and iodopsin [Kojima, D., et al. (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 6841-6845], the batho-green did not revert thermally to original gecko green but converts to the next intermediate. The photobleaching process of gecko blue was investigated by low temperature spectroscopy, and three intermediates, meta I (lambda max = approximately 470 nm), meta II (lambda max = approximately 370 nm) and meta III (lambda max = approximately 475 nm), were identified. A comparative study on the thermal behavior of meta intermediates revealed that the thermal stability of meta II intermediate of both of the gecko visual pigments is lower than that of metarhodopsin II. The result supports the idea that both the gecko visual pigments are cone-type ones.

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

    Science.gov (United States)

    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.

  13. Vegetation greenness trend (2000 to 2009) and the climate controls in the Qinghai-Tibetan Plateau

    Science.gov (United States)

    Zhang, Li; Guo, Huadong; Ji, Lei; Lei, Liping; Wang, Cuizhen; Yan, Dongmei; Li, Bin; Li, Jing

    2013-01-01

    The Qinghai-Tibetan Plateau has been experiencing a distinct warming trend, and climate warming has a direct and quick impact on the alpine grassland ecosystem. We detected the greenness trend of the grasslands in the plateau using Moderate Resolution Imaging Spectroradiometer data from 2000 to 2009. Weather station data were used to explore the climatic drivers for vegetation greenness variations. The results demonstrated that the region-wide averaged normalized difference vegetation index (NDVI) increased at a rate of 0.036  yr−1. Approximately 20% of the vegetation areas, which were primarily located in the northeastern plateau, exhibited significant NDVI increase trend (p-value plateau. A strong positive relationship between NDVI and precipitation, especially in the northeastern plateau, suggested that precipitation was a favorable factor for the grassland NDVI. Negative correlations between NDVI and temperature, especially in the southern plateau, indicated that higher temperature adversely affected the grassland growth. Although a warming climate was expected to be beneficial to the vegetation growth in cold regions, the grasslands in the central and southwestern plateau showed a decrease in trends influenced by increased temperature coupled with decreased precipitation.

  14. Influences of Product Temperature on Emotional Responses to, and Sensory Attributes of, Coffee and Green Tea Beverages

    Science.gov (United States)

    Pramudya, Ragita C.; Seo, Han-Seok

    2018-01-01

    Coffee and green tea are popular beverages consumed at both hot and cold temperatures. When people consume hot beverages concurrently with other activities, they may experience at different temperatures over the period of consumption. However, there has been limited research investigating the effects of product temperatures on emotional responses and sensory attributes of beverages. This study aimed to determine whether emotional responses to, and sensory attributes of, brewed coffee and green tea vary as a function of sample temperature. Using a check-all-that-apply (CATA) method, 157 participants (79 for coffee and 78 for green tea) were asked to evaluate either coffee or green tea samples served at cold (5°C), ambient (25°C), and hot (65°C) temperatures with respect to emotional responses and sensory attributes. The results showed that sample temperature could have significant influences on emotional responses to, and sensory attributes of, coffee and green tea samples. More specifically, 6 and 18 sensory attributes of coffee and green tea samples, respectively, significantly differed with sample temperature. Beverage samples evaluated at 65°C were characterized, regardless of activation/arousal level, by positive emotional responses terms and favorable sensory attributes. While beverages evaluated at 25°C were associated more with negative emotional responses with low activation/arousal, those evaluated at 5°C were more frequently characterized as having negative emotional responses with high activation/arousal. Sensory and emotional drivers of liking for both coffee and green tea differed both with sample temperature and gender. While both emotional responses and sensory attributes were identified as drivers of liking among females, only emotional responses were identified as drivers of liking among males. In conclusion, this study provides empirical evidence that both emotional responses to, and sensory attributes of, coffee and green tea beverages can

  15. High-temperature plastic flow of a precipitation-hardened FeCoNiCr high entropy alloy

    Energy Technology Data Exchange (ETDEWEB)

    He, J.Y.; Wang, H.; Wu, Y.; Liu, X.J. [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Nieh, T.G. [Department of Materials Science and Engineering, the University of Tennessee, Knoxville, TN 37996 (United States); Lu, Z.P., E-mail: luzhaoping@163.com [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China)

    2017-02-16

    In this work, we systematically investigated flow behavior of a high entropy alloy (HEA) strengthened by coherent γ′ precipitates in the temperature range of 1023–1173 K. In contrast to the single-phase FeCoNiCrMn HEA, this precipitate-hardened alloy, i.e., (FeCoNiCr){sub 94}Ti{sub 2}Al{sub 4}, exhibited large reduction of the steady-state strain rate (by ~2 orders of magnitude) or drastic enhancement in flow stress, indicating significant improvement in high-temperature properties. Our results showed that the deformation could be divided into two regimes. At temperatures below 1123 K, coherent γ′ precipitates effectively blocked the dislocation motion, thus resulted in a threshold stress effect. Above 1123 K, however, γ′ particles dissolved and the deformation was controlled by the ordinary dislocation climb mechanism. In addition, we conducted transmission electron microscopy to characterize dislocation-precipitate interaction to provide microstructural evidences to support our conclusion of the specific deformation mechanisms in the two temperature regimes.

  16. Influence of rolling direction and carbide precipitation on IGSCC susceptibility in hydrogenated high temperature water

    International Nuclear Information System (INIS)

    Arioka, Koji; Yamada, Takuyo; Terachi, Takumi; Chiba, Goro

    2005-01-01

    IGSCC growth behaviors of austenitic stainless steels in hydrogenated high temperature water were studied using compact type specimens (0.5T for cold worked materials). The effect of cold rolling direction, alloy composition and carbide precipitation on crack growth behaviors was studied in hydrogenated high temperature water. Then, to examine the effect of cold work and carbide precipitation on IGSCC behaviors, the role of grain boundary sliding studied in high temperature air using CT specimens. The similar dependences of carbide precipitation and cold work on IGSCC and creep behaviors suggest that grain boundary sliding might play an important role by itself or in conjunction with other reactions such as crack tip dissolution etc. (author)

  17. Effect of high-temperature pre-precipitation on microstructure and properties of 7055 aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    陈康华; 黄兰萍

    2003-01-01

    The near-solvus pre-precipitation following higher temperature solution treatment was performed on 7055 aluminum alloy. The effect of the pre-precipitation on the microstructure, age hardening and stress corrosion cracking of 7055 alloy was investigated. The optical and transmission electron microscopy results show that the near-solvus pre-precipitation can be limited to grain boundary and enhance the discontinuity of grain boundary precipitates in the sequent age. The stress corrosion cracking resistance of aged 7055 alloys could be improved with non-deteriorated strength and plasticity via the pre-precipitation.

  18. Precipitation and temperature trends over central Italy (Abruzzo Region): 1951-2012

    Science.gov (United States)

    Scorzini, Anna Rita; Leopardi, Maurizio

    2018-02-01

    This study analyses spatial and temporal trends of precipitation and temperatures over Abruzzo Region (central Italy), using historical climatic data from a dense observation network. The results show a general, although not significant, negative trend in the regionally averaged annual precipitation (- 1.8% of the yearly mean rainfall per decade). This reduction is particularly evident in winter, especially at mountain stations (average - 3% change/decade). Despite this general decreasing trend, a partial rainfall recovery is observed after the 1980s. Furthermore, the majority of meteorological stations register a significant warming over the last 60 years, (mean annual temperature increase of + 0.15 °C/decade), which reflects a rise in both minimum and maximum temperatures, with the latter generally increasing at a faster rate. Spring and summer are the seasons which contribute most to the general temperature increase, in particular at high elevation sites, which exhibit a more pronounced warming (+ 0.24 °C/decade). However, this tendency has not been uniform over 1951-2012, but it has been characterised by a cooling phenomenon in the first 30 years (1951-1981), followed by an even stronger warming during the last three decades (1982-2012). Finally, correlations between the climatic variables and the dominant teleconnection patterns in the Mediterranean basin are analysed to identify the potential influence of large-scale atmospheric dynamics on observed trends in Abruzzo. The results highlight the dominant role of the East-Atlantic pattern on seasonal temperatures, while more spatially heterogeneous associations, depending on the complex topography of the region, are identified between winter precipitation and the North Atlantic Oscillation, East-Atlantic and East-Atlantic/Western Russian patterns.

  19. Precipitation Strengthenable NiTiPd High Temperature Shape Memory Alloys

    Science.gov (United States)

    Bigelow, Glen; Garg, Anita; Benafan, Othmane; Noebe, Ronald; Gaydosh, Darrell; Padula, Santo, II

    2017-01-01

    In binary NiTi alloys, it has long been known that Ni-rich alloys can be heat treated to produce precipitates which both strengthen the matrix against dislocations and improve the behavior of the material under thermal and mechanical cycling. Within recent years, the same effect has been observed in Ni-rich NiTiHf high temperature shape memory alloys and heat treatment regimens have been defined which will reliably produce improved properties. In NiTiPd alloys, precipitation has also been observed, but studies are still underway to define reliable heat treatments and compositions which will provide a balance of strengthening and good thermomechanical properties. For this study, a series of NiTi-32 at.Pd alloys was produced to determine the effect of changing nickeltitanium content on the transformation behavior and heat treatability of the material. Samples were aged at temperatures between 350C and 450C for times up to 100 hours. Actuation type behavior was evaluated using uniaxial constant force thermal cycling (UCFTC) to determine the effect of composition and aging on the material behavior. TEMSEM was used to evaluate the microstructure and determine the types of precipitates formed. The correlation between composition, heat treat, microstructure, and thermomechanical behavior will be addressed and discussed.

  20. Probabilistic precipitation and temperature downscaling of the Twentieth Century Reanalysis over France

    Science.gov (United States)

    Caillouet, Laurie; Vidal, Jean-Philippe; Sauquet, Eric; Graff, Benjamin

    2016-03-01

    This work proposes a daily high-resolution probabilistic reconstruction of precipitation and temperature fields in France over the 1871-2012 period built on the NOAA Twentieth Century global extended atmospheric reanalysis (20CR). The objective is to fill in the spatial and temporal data gaps in surface observations in order to improve our knowledge on the local-scale climate variability from the late nineteenth century onwards. The SANDHY (Stepwise ANalogue Downscaling method for HYdrology) statistical downscaling method, initially developed for quantitative precipitation forecast, is used here to bridge the scale gap between large-scale 20CR predictors and local-scale predictands from the Safran high-resolution near-surface reanalysis, available from 1958 onwards only. SANDHY provides a daily ensemble of 125 analogue dates over the 1871-2012 period for 608 climatically homogeneous zones paving France. Large precipitation biases in intermediary seasons are shown to occur in regions with high seasonal asymmetry like the Mediterranean. Moreover, winter and summer temperatures are respectively over- and under-estimated over the whole of France. Two analogue subselection methods are therefore developed with the aim of keeping the structure of the SANDHY method unchanged while reducing those seasonal biases. The calendar selection keeps the analogues closest to the target calendar day. The stepwise selection applies two new analogy steps based on similarity of the sea surface temperature (SST) and the large-scale 2 m temperature (T). Comparisons to the Safran reanalysis over 1959-2007 and to homogenized series over the whole twentieth century show that biases in the interannual cycle of precipitation and temperature are reduced with both methods. The stepwise subselection moreover leads to a large improvement of interannual correlation and reduction of errors in seasonal temperature time series. When the calendar subselection is an easily applicable method suitable in

  1. Effects of different oxyanions in solution on the precipitation of jarosite at room temperature.

    Science.gov (United States)

    Yeongkyoo, Kim

    2018-04-09

    The effects of five different oxyanions, AsO 4 , SeO 3 , SeO 4 , MoO 4 , and CrO 4 , on the precipitation of jarosite at room temperature were investigated by X-ray diffraction, scanning electron microscopy, and chemical analysis. Different amounts (2, 5, and 10 mol%) of oxyanions in the starting solution and different aging times (1 h-40 days) were used for the experiment. In the initial stage, only the amorphous phase appears for all samples. With increasing aging time, jarosite and jarosite with oxyanions start precipitating at room temperature with different precipitation rates and crystallinities. Jarosite with AsO 4 shows the lowest precipitation rate and lowest crystallinity. With increasing amounts of oxyanions, the crystallization rate decreases, especially for jarosite with AsO 4 . The jarosite samples with CrO 4 and SeO 4 show the fastest precipitation and highest crystallinities. For the jarosite samples with a low precipitation rate and low crystallinity, the amorphous phase contains high concentrations of oxyanions, probably because of the fast precipitation of the amorphous iron oxyanion phase; however, the phase with fast jarosite precipitation contains fewer oxyanions. The results show that coprecipitation of jarosite can play a more important role in controlling the behavior of CrO 4 than AsO 4 in acid mine drainage. Copyright © 2018 Elsevier B.V. All rights reserved.

  2. Appearance probability of certain precipitation quantities and temperature sums > 100S during the growing period

    International Nuclear Information System (INIS)

    Dimitrovska, Blaga; Dimitrovski, Zoran; Ristevski, Pece

    2004-01-01

    In this paper are given probabilities for determined precipitation amounts existence and temperature sums >10 o C (in percentages) for fifteen measure stations in the Republic of Macedonia for the vegetative period of the year (from 1 st of April until 31st of October) and for period 1951-2000. Using the precipitation amounts and sums of temperatures >10 o C for the vegetative period of the year we, calculated hydro thermic coefficient (HTC) by Seljaninov for each year of the period 1951-2000. From the HTC values we categorized the drought for each measure station using criteria by S.Otorepec. Calculating the probabilities for determined precipitation amounts existence and temperature summes > 10 o C occurrence is very important for water balance calculation, irrigation norms etc.(Author)

  3. Late Quaternary glacier sensitivity to temperature and precipitation distribution in the Southern Alps of New Zealand

    Energy Technology Data Exchange (ETDEWEB)

    Ann V. Rowan; Simon H. Brocklehurst; David M. Schultz; Mitchell A. Plummer; Leif S. Anderson; Neil F. Glasser

    2014-05-01

    Glaciers respond to climate variations and leave geomorphic evidence that represents an important terrestrial paleoclimate record. However, the accuracy of paleoclimate reconstructions from glacial geology is limited by the challenge of representing mountain meteorology in numerical models. Precipitation is usually treated in a simple manner and yet represents difficult-to-characterize variables such as amount, distribution, and phase. Furthermore, precipitation distributions during a glacial probably differed from present-day interglacial patterns. We applied two models to investigate glacier sensitivity to temperature and precipitation in the eastern Southern Alps of New Zealand. A 2-D model was used to quantify variations in the length of the reconstructed glaciers resulting from plausible precipitation distributions compared to variations in length resulting from change in mean annual air temperature and precipitation amount. A 1-D model was used to quantify variations in length resulting from interannual climate variability. Assuming that present-day interglacial values represent precipitation distributions during the last glacial, a range of plausible present-day precipitation distributions resulted in uncertainty in the Last Glacial Maximum length of the Pukaki Glacier of 17.1?km (24%) and the Rakaia Glacier of 9.3?km (25%), corresponding to a 0.5°C difference in temperature. Smaller changes in glacier length resulted from a 50% decrease in precipitation amount from present-day values (-14% and -18%) and from a 50% increase in precipitation amount (5% and 9%). Our results demonstrate that precipitation distribution can produce considerable variation in simulated glacier extents and that reconstructions of paleoglaciers should include this uncertainty.

  4. The theory, direction, and magnitude of ecosystem fire probability as constrained by precipitation and temperature.

    Science.gov (United States)

    Guyette, Richard; Stambaugh, Michael C; Dey, Daniel; Muzika, Rose Marie

    2017-01-01

    The effects of climate on wildland fire confronts society across a range of different ecosystems. Water and temperature affect the combustion dynamics, irrespective of whether those are associated with carbon fueled motors or ecosystems, but through different chemical, physical, and biological processes. We use an ecosystem combustion equation developed with the physical chemistry of atmospheric variables to estimate and simulate fire probability and mean fire interval (MFI). The calibration of ecosystem fire probability with basic combustion chemistry and physics offers a quantitative method to address wildland fire in addition to the well-studied forcing factors such as topography, ignition, and vegetation. We develop a graphic analysis tool for estimating climate forced fire probability with temperature and precipitation based on an empirical assessment of combustion theory and fire prediction in ecosystems. Climate-affected fire probability for any period, past or future, is estimated with given temperature and precipitation. A graphic analyses of wildland fire dynamics driven by climate supports a dialectic in hydrologic processes that affect ecosystem combustion: 1) the water needed by plants to produce carbon bonds (fuel) and 2) the inhibition of successful reactant collisions by water molecules (humidity and fuel moisture). These two postulates enable a classification scheme for ecosystems into three or more climate categories using their position relative to change points defined by precipitation in combustion dynamics equations. Three classifications of combustion dynamics in ecosystems fire probability include: 1) precipitation insensitive, 2) precipitation unstable, and 3) precipitation sensitive. All three classifications interact in different ways with variable levels of temperature.

  5. The theory, direction, and magnitude of ecosystem fire probability as constrained by precipitation and temperature.

    Directory of Open Access Journals (Sweden)

    Richard Guyette

    Full Text Available The effects of climate on wildland fire confronts society across a range of different ecosystems. Water and temperature affect the combustion dynamics, irrespective of whether those are associated with carbon fueled motors or ecosystems, but through different chemical, physical, and biological processes. We use an ecosystem combustion equation developed with the physical chemistry of atmospheric variables to estimate and simulate fire probability and mean fire interval (MFI. The calibration of ecosystem fire probability with basic combustion chemistry and physics offers a quantitative method to address wildland fire in addition to the well-studied forcing factors such as topography, ignition, and vegetation. We develop a graphic analysis tool for estimating climate forced fire probability with temperature and precipitation based on an empirical assessment of combustion theory and fire prediction in ecosystems. Climate-affected fire probability for any period, past or future, is estimated with given temperature and precipitation. A graphic analyses of wildland fire dynamics driven by climate supports a dialectic in hydrologic processes that affect ecosystem combustion: 1 the water needed by plants to produce carbon bonds (fuel and 2 the inhibition of successful reactant collisions by water molecules (humidity and fuel moisture. These two postulates enable a classification scheme for ecosystems into three or more climate categories using their position relative to change points defined by precipitation in combustion dynamics equations. Three classifications of combustion dynamics in ecosystems fire probability include: 1 precipitation insensitive, 2 precipitation unstable, and 3 precipitation sensitive. All three classifications interact in different ways with variable levels of temperature.

  6. Effect of solution annealing temperature on precipitation in 2205 duplex stainless steel

    International Nuclear Information System (INIS)

    Kashiwar, A.; Vennela, N. Phani; Kamath, S.L.; Khatirkar, R.K.

    2012-01-01

    In the present study, effect of solution annealing temperature (1050 °C and 1100 °C) and isothermal ageing (700 °C: 15 min to 6 h) on the microstructural changes in 2205 duplex stainless steel has been investigated systematically. Scanning electron microscopy and X-ray diffraction were adopted to follow the microstructural evolution, while an energy dispersive spectrometer attached to scanning electron microscope was used to obtain localised chemical information of various phases. The ferritic matrix of the two phase 2205 duplex stainless steel (∼ 45% ferrite and ∼ 55% austenite) undergoes a series of metallurgical transformations during ageing—formation of secondary austenite (γ 2 ) and precipitation of Cr and Mo rich intermetallic (chi-χ and sigma-σ) phases. For solution annealing at 1050 °C, significant amount of carbides were observed in the ferrite grains after 1 h of ageing at 700 °C. χ Phase precipitated after the precipitation of carbides—preferentially at the ferrite–ferrite and also at the ferrite–austenite boundaries. σ Phase was not observed in significant quantity even after 6 h of ageing. The sequence of precipitation in samples solution annealed at 1050 °C was found to be carbides → χ → σ. On the contrary, for samples solution annealed at 1100 °C, the precipitation of χ phase was negligible. χ Phase precipitated before σ phase, preferentially along the ferrite–ferrite grain boundaries and was later consumed in the σ phase precipitation. The σ phase precipitated via the eutectoid transformation of ferrite to yield secondary austenite γ 2 and σ phase in the ferrite and along the ferrite–austenite grain boundaries. An increase in the volume fraction of γ 2 and σ phase with simultaneous decrease in the ferrite was evidenced with ageing. - Highlights: ► Effect of solution annealing temperature on microstructural evolution is studied. ► χ Phase precipitated preferentially in the samples solution annealed at

  7. Effect of solution annealing temperature on precipitation in 2205 duplex stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Kashiwar, A., E-mail: akashiwar@gmail.com [Department of Metallurgical and Materials Engineering, Visvesvaraya National Institute of Technology (VNIT), South Ambazari Road, Nagpur-440010, Maharashtra (India); Vennela, N. Phani, E-mail: phanivennela@gmail.com [Department of Metallurgical and Materials Engineering, Visvesvaraya National Institute of Technology (VNIT), South Ambazari Road, Nagpur-440010, Maharashtra (India); Kamath, S.L., E-mail: kamath@iitb.ac.in [Department of Metallurgical Engineering and Materials Science, Indian Institute of Technology Bombay (IITB), Powai, Mumbai-400076, Maharashtra (India); Khatirkar, R.K., E-mail: rajesh.khatirkar@gmail.com [Department of Metallurgical and Materials Engineering, Visvesvaraya National Institute of Technology (VNIT), South Ambazari Road, Nagpur-440010, Maharashtra (India)

    2012-12-15

    In the present study, effect of solution annealing temperature (1050 Degree-Sign C and 1100 Degree-Sign C) and isothermal ageing (700 Degree-Sign C: 15 min to 6 h) on the microstructural changes in 2205 duplex stainless steel has been investigated systematically. Scanning electron microscopy and X-ray diffraction were adopted to follow the microstructural evolution, while an energy dispersive spectrometer attached to scanning electron microscope was used to obtain localised chemical information of various phases. The ferritic matrix of the two phase 2205 duplex stainless steel ({approx} 45% ferrite and {approx} 55% austenite) undergoes a series of metallurgical transformations during ageing-formation of secondary austenite ({gamma}{sub 2}) and precipitation of Cr and Mo rich intermetallic (chi-{chi} and sigma-{sigma}) phases. For solution annealing at 1050 Degree-Sign C, significant amount of carbides were observed in the ferrite grains after 1 h of ageing at 700 Degree-Sign C. {chi} Phase precipitated after the precipitation of carbides-preferentially at the ferrite-ferrite and also at the ferrite-austenite boundaries. {sigma} Phase was not observed in significant quantity even after 6 h of ageing. The sequence of precipitation in samples solution annealed at 1050 Degree-Sign C was found to be carbides {yields} {chi} {yields} {sigma}. On the contrary, for samples solution annealed at 1100 Degree-Sign C, the precipitation of {chi} phase was negligible. {chi} Phase precipitated before {sigma} phase, preferentially along the ferrite-ferrite grain boundaries and was later consumed in the {sigma} phase precipitation. The {sigma} phase precipitated via the eutectoid transformation of ferrite to yield secondary austenite {gamma}{sub 2} and {sigma} phase in the ferrite and along the ferrite-austenite grain boundaries. An increase in the volume fraction of {gamma}{sub 2} and {sigma} phase with simultaneous decrease in the ferrite was evidenced with ageing. - Highlights

  8. Variability and trends of wet season temperature in the Sudano-Sahelian zone and relationships with precipitation

    Science.gov (United States)

    Oueslati, Boutheina; Camberlin, Pierre; Zoungrana, Joël; Roucou, Pascal; Diallo, Saliou

    2018-02-01

    The relationships between precipitation and temperature in the central Sudano-Sahelian belt are investigated by analyzing 50 years (1959-2008) of observed temperature (Tx and Tn) and rainfall variations. At daily time-scale, both Tx and Tn show a marked decrease as a response to rainfall occurrence, with a strongest departure from normal 1 day after the rainfall event (-0.5 to -2.5 °C depending on the month). The cooling is slightly larger when heavy rainfall events (>5 mm) are considered. The temperature anomalies weaken after the rainfall event, but are still significant several days later. The physical mechanisms accounting for the temperature response to precipitation are analysed. The Tx drop is accounted for by reduced incoming solar radiation associated with increased cloud cover and increased surface evaporation following surface moistening. The effect of evaporation becomes dominant a few days after the rainfall event. The reduced daytime heat storage and the subsequent sensible heat flux result in a later negative Tn anomaly. The effect of rainfall variations on temperature is significant for long-term warming trends. The rainfall decrease experienced between 1959 and 2008 accounts for a rainy season Tx increase of 0.15 to 0.3 °C, out of a total Tx increase of 1.3 to 1.5 °C. These results have strong implications on the assessment of future temperature changes. The dampening or amplifying effects of precipitation are determined by the sign of future precipitation trends. Confidence on temperature changes under global warming partly depend on the robustness of precipitation projections.

  9. Green roofs: potential at LANL

    Energy Technology Data Exchange (ETDEWEB)

    Pacheco, Elena M [Los Alamos National Laboratory

    2009-01-01

    Green roofs, roof systems that support vegetation, are rapidly becoming one of the most popular sustainable methods to combat urban environmental problems in North America. An extensive list of literature has been published in the past three decades recording the ecological benefits of green roofs; and now those benefits have been measured in enumerated data as a means to analyze the costs and returns of green roof technology. Most recently several studies have made substantial progress quantifying the monetary savings associated with storm water mitigation, the lessoning of the Urban Heat Island, and reduction of building cooling demands due to the implementation of green roof systems. Like any natural vegetation, a green roof is capable of absorbing the precipitation that falls on it. This capability has shown to significantly decrease the amount of storm water runoff produced by buildings as well as slow the rate at which runoff is dispensed. As a result of this reduction in volume and velocity, storm drains and sewage systems are relieved of any excess stress they might experience in a storm. For many municipalities and private building owners, any increase in storm water mitigation can result in major tax incentives and revenue that does not have to be spent on extra water treatments. Along with absorption of water, vegetation on green roofs is also capable of transpiration, the process by which moisture is evaporated into the air to cool ambient temperatures. This natural process aims to minimize the Urban Heat Island Effect, a phenomenon brought on by the dark and paved surfaces that increases air temperatures in urban cores. As the sun distributes solar radiation over a city's area, dark surfaces such as bitumen rooftops absorb solar rays and their heat. That heat is later released during the evening hours and the ambient temperatures do not cool as they normally would, creating an island of constant heat. Such excessively high temperatures induce heat

  10. Using Historical Precipitation, Temperature, and Runoff Observations to Evaluate Evaporation Formulations in Land Surface Models

    Science.gov (United States)

    Koster, Randal D.; Mahanama, P. P.

    2012-01-01

    Key to translating soil moisture memory into subseasonal precipitation and air temperature forecast skill is a realistic treatment of evaporation in the forecast system used - in particular, a realistic treatment of how evaporation responds to variations in soil moisture. The inherent soil moisture-evaporation relationships used in today's land surface models (LSMs), however, arguably reflect little more than guesswork given the lack of evaporation and soil moisture data at the spatial scales represented by regional and global models. Here we present a new approach for evaluating this critical aspect of LSMs. Seasonally averaged precipitation is used as a proxy for seasonally-averaged soil moisture, and seasonally-averaged air temperature is used as a proxy for seasonally-averaged evaporation (e.g., more evaporative cooling leads to cooler temperatures) the relationship between historical precipitation and temperature measurements accordingly mimics in certain important ways nature's relationship between soil moisture and evaporation. Additional information on the relationship is gleaned from joint analysis of precipitation and streamflow measurements. An experimental framework that utilizes these ideas to guide the development of an improved soil moisture-evaporation relationship is described and demonstrated.

  11. Climate Prediction Center(CPC) Monthly U.S. Precipitation and Temperature Summary

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Monthly U.S. minimum and maximum temperatures in whole degrees Fahrenheit and reported and estimated precipitation amounts in hundredths of inches(ex 100 is 1.00...

  12. Climate Prediction Center(CPC)Daily U.S. Precipitation and Temperature Summary

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Daily U.S. minimum and maximum temperatures in whole degrees Fahrenheit and reported and estimated precipitation amounts in hundredths of inches(ex 100 is 1.00...

  13. Climate Prediction Center (CPC)Weekly U.S. Precipitation and Temperature Summary

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Weekly U.S. minimum and maximum temperatures in whole degrees Fahrenheit and reported and estimated precipitation amounts in hundredths of inches(ex 100 is 1.00...

  14. Green roof hydrologic performance and modeling: a review.

    Science.gov (United States)

    Li, Yanling; Babcock, Roger W

    2014-01-01

    Green roofs reduce runoff from impervious surfaces in urban development. This paper reviews the technical literature on green roof hydrology. Laboratory experiments and field measurements have shown that green roofs can reduce stormwater runoff volume by 30 to 86%, reduce peak flow rate by 22 to 93% and delay the peak flow by 0 to 30 min and thereby decrease pollution, flooding and erosion during precipitation events. However, the effectiveness can vary substantially due to design characteristics making performance predictions difficult. Evaluation of the most recently published study findings indicates that the major factors affecting green roof hydrology are precipitation volume, precipitation dynamics, antecedent conditions, growth medium, plant species, and roof slope. This paper also evaluates the computer models commonly used to simulate hydrologic processes for green roofs, including stormwater management model, soil water atmosphere and plant, SWMS-2D, HYDRUS, and other models that are shown to be effective for predicting precipitation response and economic benefits. The review findings indicate that green roofs are effective for reduction of runoff volume and peak flow, and delay of peak flow, however, no tool or model is available to predict expected performance for any given anticipated system based on design parameters that directly affect green roof hydrology.

  15. Environment, vegetation and greenness (NDVI) along the North America and Eurasia Arctic transects

    International Nuclear Information System (INIS)

    Walker, D A; Raynolds, M K; Kuss, P; Kade, A N; Epstein, H E; Frost, G V; Kopecky, M A; Daniëls, F J A; Leibman, M O; Moskalenko, N G; Khomutov, A V; Matyshak, G V; Khitun, O V; Forbes, B C; Bhatt, U S; Vonlanthen, C M; Tichý, L

    2012-01-01

    Satellite-based measurements of the normalized difference vegetation index (NDVI; an index of vegetation greenness and photosynthetic capacity) indicate that tundra environments are generally greening and becoming more productive as climates warm in the Arctic. The greening, however, varies and is even negative in some parts of the Arctic. To help interpret the space-based observations, the International Polar Year (IPY) Greening of the Arctic project conducted ground-based surveys along two >1500 km transects that span all five Arctic bioclimate subzones. Here we summarize the climate, soil, vegetation, biomass, and spectral information collected from the North America Arctic transect (NAAT), which has a more continental climate, and the Eurasia Arctic transect (EAT), which has a more oceanic climate. The transects have broadly similar summer temperature regimes and overall vegetation physiognomy, but strong differences in precipitation, especially winter precipitation, soil texture and pH, disturbance regimes, and plant species composition and structure. The results indicate that summer warmth and NDVI increased more strongly along the more continental transect. (letter)

  16. Greening in sunflower butter cookies as a function of egg replacers and baking temperature.

    Science.gov (United States)

    Rogers, Amanda; Hahn, Lan; Pham, Vu; Were, Lilian

    2018-04-01

    Chlorogenic acid (CGA) binding to proteins in alkaline conditions results in the production of green trihydroxy benzacradine (TBA) derivatives. The formation of TBA derivatives could decrease product quality due to the potential losses in soluble protein and antioxidants and the production of an undesirable green color. To determine how cookie formulation affected the formation of TBA derivatives in sunflower butter cookies, two egg replacers (chia and banana) and two baking temperatures (162.8 and 190.6 °C) were used. Moisture, greening intensity, CGA content and antioxidant capacity were measured. Cookies made with egg and baked at 162.8 °C had the highest moisture, internal greening intensity, and TBA derivative formation, in addition to lower CGA content and antioxidant capacity. Cookies made with banana baked at 190.6 °C produced the opposite outcome with 35, 4, and 23% less internal greening, moisture, and TBA derivatives, respectively, and 90 and 76% higher CGA and antioxidant capacity. Internal greening was positively correlated with moisture and adduct concentration, and negatively correlated with spread factor and CGA content. Moisture had a significant impact on greening, which indicates that baking temperature and cookie dough formulation can be modified to produce a less green cookie with more unreacted antioxidants and protein.

  17. Time Temperature-Precipitation Behavior in An Al-Cu-Li Alloy 2195

    Science.gov (United States)

    Chen, P. S.; Bhat, B. N.

    1999-01-01

    Al-Cu-Li alloy 2195, with its combination of good cryogenic properties, low density, and high modulus, has been selected by NASA to be the main structural alloy of the Super Light Weight Tank (SLWT) for the Space Shuttle. Alloy 2195 is strengthened by an aging treatment that precipitates a particular precipitate, labeled as T1(Al2CuLi). Other phases, such as GP zone, (theta)', (theta)", theta, (delta)', S' are also present in this alloy when artificially aged. Cryogenic strength and fracture toughness are critical to the -SLWT application, since the SLWT will house liquid oxygen and hydrogen. Motivation for the Time-Temperature-Precipitation (TTP) study at lower temperature (lower than 350 F) comes in part from a recent study by Chen, The study found that the cryogenic fracture toughness of alloy 2195 is greatly influenced by the phases present in the matrix and subgrain boundaries. Therefore, the understanding of TTP behavior can help develop a guideline to select appropriate heat treatment conditions for the desirable applications. The study of TTP behavior at higher temperature (400 to 1000 F) was prompted by the fact that the SLWT requires a welded construction. Heat conduction from the weld pool affects the microstructure in the heat-affected zone (HAZ), which leads to changes in the mechanical properties. Furthermore, the SLWT may need repair welding for more than one time and any additional thermal cycles will increase precipitate instability and promote phase transformation. As a result considerable changes in HAZ microstructure and mechanical properties are expected during the construction of the SLWT. Therefore, the TTP diagrams can serve to understand the thermal history of the alloy by analyzing the welded microstructure. In the case welding, the effects of thermal cycles on the microstructure and mechanical properties can be predicted with the aid of the TTP diagrams. The 2195 alloy (nominally Al + 4 pct Cu + 1 pct Li + 0.3 pct Ag + 0.3 pct Mg + 0

  18. Rising Mediterranean Sea Surface Temperatures Amplify Extreme Summer Precipitation in Central Europe

    Science.gov (United States)

    Volosciuk, Claudia; Maraun, Douglas; Semenov, Vladimir A.; Tilinina, Natalia; Gulev, Sergey K.; Latif, Mojib

    2016-08-01

    The beginning of the 21st century was marked by a number of severe summer floods in Central Europe associated with extreme precipitation (e.g., Elbe 2002, Oder 2010 and Danube 2013). Extratropical storms, known as Vb-cyclones, cause summer extreme precipitation events over Central Europe and can thus lead to such floodings. Vb-cyclones develop over the Mediterranean Sea, which itself strongly warmed during recent decades. Here we investigate the influence of increased Mediterranean Sea surface temperature (SST) on extreme precipitation events in Central Europe. To this end, we carry out atmosphere model simulations forced by average Mediterranean SSTs during 1970-1999 and 2000-2012. Extreme precipitation events occurring on average every 20 summers in the warmer-SST-simulation (2000-2012) amplify along the Vb-cyclone track compared to those in the colder-SST-simulation (1970-1999), on average by 17% in Central Europe. The largest increase is located southeast of maximum precipitation for both simulated heavy events and historical Vb-events. The responsible physical mechanism is increased evaporation from and enhanced atmospheric moisture content over the Mediterranean Sea. The excess in precipitable water is transported from the Mediterranean Sea to Central Europe causing stronger precipitation extremes over that region. Our findings suggest that Mediterranean Sea surface warming amplifies Central European precipitation extremes.

  19. Evaluation of a bias correction method applied to downscaled precipitation and temperature reanalysis for the Rhine basin

    NARCIS (Netherlands)

    Terink, W.; Hurkmans, R.T.W.L.; Torfs, P.J.J.F.; Uijlenhoet, R.

    2010-01-01

    In many climate impact studies hydrological models are forced with meteorological data without an attempt to assess the quality of these data. The objective of this study was to compare downscaled ERA15 (ECMWF-reanalysis data) precipitation and temperature with observed precipitation and temperature

  20. Study on variability of temperature and precipitation conditions in the South Eastern Bulgaria

    International Nuclear Information System (INIS)

    Koleva-Lizama, Ivanka; Lizama Rivas, Bernardo

    2004-01-01

    Freshwater resources are an essential component of the earth's hydrosphere and an indispensable part of all terrestrial ecosystems. The freshwater environment is characterized by the hydrological cycle. Global climate change and pollution could also have an impact on freshwater resources and their availability. There is now sufficient evidence, accepted by internationally respected scientists, that human activity is having an effect on the climate of the planet. The effects are mostly the result of greenhouse gas emissions, and are in addition to naturally occurring climate change. The impacts of climate change on water resources are displayed in every sector of water system. The temperature and precipitation are the most important factors, which affect on water resources. On the basis of meteorological data for more than 45 years from several gauging stations is made an analysis on the peculiarities of the climatic conditions in the southeastern Bulgaria. In order to trace the variability of historical precipitation and temperature series the analysis of trend and deviations from climate mean of recommended by WMO 'climate normal' period 1961-1990 was used. Precipitation over the southeastern Bulgaria has a significant variability over wide range of temporal and spatial scales. The annual precipitation data were examined for evidence of a secular trend by calculation of a linear best fit for the 1952 to 2000. The tendency of rainfall decrease was determined. The drought period in the studied region is noticeable during the summer. It should be concluded that temperature increase and precipitation decrease conduct to drought in the region and it may have more severe impacts on agriculture, water supply and society.(Author)

  1. The impact of Arctic and North Atlantic oscillation on temperature and precipitation anomalies in Serbia

    Directory of Open Access Journals (Sweden)

    Pavlović-Berdon Nada

    2012-01-01

    Full Text Available The impact of the Arctic Oscillations (AO and the North Atlantic Oscillations (NAO is considered as the most prominent of atmospheric oscillations in the area of the northern hemisphere from the United States to Siberia and from the Arctic to the subtropical Atlantic. The aim of this study was to determine how these fluctuations affect the temperature and precipitation in Serbia. This paper explores the impact for the period of 50 years (1958-2007 by months and in 20 synoptic stations. The influence of the AO on temperature anomalies in Serbia can be seen by the correlation coefficient, the largest in the month of January, while its impact on precipitation is the largest in the month of February. After the test of linear correlation between the NAO index and temperature anomalies for the base period 1971-2000 for 20 synoptic stations in Serbia, it has been found that the highest correlation is in the month of January. The correlation between the NAO and the precipitation anomalies for the stations mentioned above is the highest in the month of February. Spatial patterns of the AO and the NAO influence on temperature in January and on precipitation in February were obtained by applying principal component analysis.

  2. Daily temperature and precipitation extremes in the Baltic Sea region derived from the BaltAn65+ reanalysis

    Science.gov (United States)

    Toll, Velle; Post, Piia

    2018-04-01

    Daily 2-m temperature and precipitation extremes in the Baltic Sea region for the time period of 1965-2005 is studied based on data from the BaltAn65 + high resolution atmospheric reanalysis. Moreover, the ability of regional reanalysis to capture extremes is analysed by comparing the reanalysis data to gridded observations. The shortcomings in the simulation of the minimum temperatures over the northern part of the region and in the simulation of the extreme precipitation over the Scandinavian mountains in the BaltAn65+ reanalysis data are detected and analysed. Temporal trends in the temperature and precipitation extremes in the Baltic Sea region, with the largest increases in temperature and precipitation in winter, are detected based on both gridded observations and the BaltAn65+ reanalysis data. However, the reanalysis is not able to capture all of the regional trends in the extremes in the observations due to the shortcomings in the simulation of the extremes.

  3. United States Historical Climatology Network Daily Temperature and Precipitation Data (1871-1997)

    Energy Technology Data Exchange (ETDEWEB)

    Easterling, D.R.

    2002-10-28

    This document describes a database containing daily observations of maximum and minimum temperature, precipitation amount, snowfall amount, and snow depth from 1062 observing stations across the contiguous US. This database is an expansion and update of the original 138-station database previously released by the Carbon Dioxide Information Analysis Center (CDIAC) as CDIAC numeric data package NDP-042. These 1062 stations are a subset of the 1221-station US Historical Climatology Network (HCN), a monthly database compiled by the National Climatic Data Center (Asheville, North Carolina) that has been widely used in analyzing US climate. Data from 1050 of these daily records extend into the 1990s, while 990 of these extend through 1997. Most station records are essentially complete for at least 40 years; the latest beginning year of record is 1948. Records from 158 stations begin prior to 1900, with that of Charleston, South Carolina beginning the earliest (1871). The daily resolution of these data makes them extremely valuable for studies attempting to detect and monitor long-term climatic changes on a regional scale. Studies using daily data may be able to detect changes in regional climate that would not be apparent from analysis of monthly temperature and precipitation data. Such studies may include analyses of trends in maximum and minimum temperatures, temperature extremes, daily temperature range, precipitation ''event size'' frequency, and the magnitude and duration of wet and dry periods. The data are also valuable in areas such as regional climate model validation and climate change impact assessment. This database is available free of charge from CDIAC as a numeric data package (NDP).

  4. Phase transformation and precipitation in aged Ti-Ni-Hf high-temperature shape memory alloys

    International Nuclear Information System (INIS)

    Meng, X.L.; Cai, W.; Zheng, Y.F.; Zhao, L.C.

    2006-01-01

    More attention has been paid to ternary Ti-Ni-Hf high-temperature shape memory alloys (SMAs) due to their high phase transformation temperatures, good thermal stability and low cost. However, the Ti-Ni-Hf alloys have been found to have low ductility and only about 3% shape memory effect and these have hampered their applications. It is well known that there are three methods to improve the shape memory properties of high-temperature SMAs: (a) cold rolling + annealing; (b) adding another element to the alloy; (c) aging. These methods are not suitable to improve the properties of Ti-Ni-Hf alloys. In this paper, a method of conditioning Ni-rich Ti-Ni-Hf alloys as high-temperature SMAs by aging is presented. For Ni-rich Ti 80-x Ni x Hf 20 alloys (numbers indicate at.%) the phase transformation temperatures are on average increased by more than 100 K by aging at 823 K for 2 h. Especially for those alloys with Ni contents less than 50.6 at.%, the martensitic transformation start temperatures (M s ) are higher than 473 K after aging. Transmission electron microscopy shows the presence of (Ti + Hf) 3 Ni 4 precipitates after aging. Compared with the precipitation of Ti 3 Ni 4 particles in Ni-rich Ti-Ni alloys, the precipitation of (Ti + Hf) 3 Ni 4 particles in Ni-rich Ti-Ni-Hf alloys needs higher temperatures and longer times

  5. Preplastic strain effect on chromium carbides precipitation of type 316 stainless steel during high-temperature ageing

    International Nuclear Information System (INIS)

    Mao, X.; Zhao, W.

    1992-01-01

    Long exposure of Type 316 stainless steel to elevated temperature (400-900 o C) is known to cause high-temperature embrittlement due to chromium carbides and σ-phase precipitating in grain boundaries. Numerous investigations have been published on the mechanical properties and microstructure changes occurring during such exposure. However, no investigations exist on the preplastic deformation effect on chromium carbide precipitation in the grain matrix and grain boundary during high-temperature ageing of Type 316 stainless steel and then its effects on the room-temperature tensile properties. Since the stainless steel sometimes is deformed before use at high temperatures, it is necessary to study the preplastic strain effect of the stainless steel on the microstructure change and mechanical property change during high-temperature exposure. The purpose of the present investigation was to carry out such a study. The conclusions reached are as follows. First, chromium carbides are precipitated in deformation lines (slip lines) and then the amount of chromium carbides precipitation in the grain boundary is relatively reduced in predeformed stainless steel after ageing. Secondly, plastic strain pretreatments of and subsequent ageing treatments of Type 316 stainless steel can improve its tensile ductility. Finally, secondary cracking of aged stainless steel occurs in a normal tensile test. The secondary cracking can be reduced by adding preplastic strain into the material. (Author)

  6. Green Infrastructure, Climate Change and Spatial Planning: Learning Lessons Across Borders

    Directory of Open Access Journals (Sweden)

    André Samora-Arvela

    2017-09-01

    Full Text Available Climate change will further induce a generalized rise in temperature, heat waves, exacerbation of heat island effect, alteration of the precipitation regime variability with higher occurrence of high precipitation and flood events, reduction of quantity and quality of freshwater resources, disruption of agricultural production, leading to food security risk, degradation of recreational and aesthetic amenities, and loss of biodiversity. On other hand, Green Infrastructure, that is, the network of natural and semi-natural spaces within and around urban spaces, brings a constructive and protecting element that may mitigate and adapt to the local level impacts of climate change, strengthening local resilience. This paper presents a comparative study of various green infrastructures’ implementation based on analytics in the United States of America, United Kingdom and Portugal, and focuses on the degree of its alignment with the public policies of mitigation and adaptation to the impacts of climate change. Pursuant to the identification of successes and failures, this paper infers common strategies, goals and benchmarking on outcomes for more adequate decision implementation and sustainable spatial planning, considering the importance of green infrastructure.

  7. Quantifying the temperature-independent effect of stratospheric aerosol geoengineering on global-mean precipitation in a multi-model ensemble

    International Nuclear Information System (INIS)

    Ferraro, Angus J; Griffiths, Hannah G

    2016-01-01

    The reduction in global-mean precipitation when stratospheric aerosol geoengineering is used to counterbalance global warming from increasing carbon dioxide (CO 2 ) concentrations has been mainly attributed to the temperature-independent effect of CO 2 on atmospheric radiative cooling. We demonstrate here that stratospheric sulphate aerosol itself also acts to reduce global-mean precipitation independent of its effects on temperature. The temperature-independent effect of stratospheric aerosol geoenginering on global-mean precipitation is calculated by removing temperature-dependent effects from climate model simulations of the Geoengineering Model Intercomparison Project (GeoMIP). When sulphate aerosol is injected into the stratosphere at a rate of 5 Tg SO 2 per year the aerosol reduces global-mean precipitation by approximately 0.2 %, though multiple ensemble members are required to separate this effect from internal variability. For comparison, the precipitation reduction from the temperature-independent effect of increasing CO 2 concentrations under the RCP4.5 scenario of the future is approximately 0.5 %. The temperature-independent effect of stratospheric sulphate aerosol arises from the aerosol’s effect on tropospheric radiative cooling. Radiative transfer calculations show this is mainly due to increasing downward emission of infrared radiation by the aerosol, but there is also a contribution from the stratospheric warming the aerosol causes. Our results suggest climate model simulations of solar dimming can capture the main features of the global-mean precipitation response to stratospheric aerosol geoengineering. (letter)

  8. Isothermal Time-Temperature-Precipitation Diagram for an Aluminum Alloy 6005A by In Situ DSC Experiments

    Directory of Open Access Journals (Sweden)

    Benjamin Milkereit

    2014-03-01

    Full Text Available Time-temperature-precipitation (TTP diagrams deliver important material data, such as temperature and time ranges critical for precipitation during the quenching step of the age hardening procedure. Although the quenching step is continuous, isothermal TTP diagrams are often applied. Together with a so-called Quench Factor Analysis, they can be used to describe very different cooling paths. Typically, these diagrams are constructed based on mechanical properties or microstructures after an interrupted quenching, i.e., ex situ analyses. In recent years, an in situ calorimetric method to record continuous cooling precipitation diagrams of aluminum alloys has been developed to the application level by our group. This method has now been transferred to isothermal experiments, in which the whole heat treatment cycle was performed in a differential scanning calorimeter. The Al-Mg-Si-wrought alloy 6005A was investigated. Solution annealing at 540 °C and overcritical quenching to several temperatures between 450 °C and 250 °C were followed by isothermal soaking. Based on the heat flow curves during isothermal soaking, TTP diagrams were determined. An appropriate evaluation method has been developed. It was found that three different precipitation reactions in characteristic temperature intervals exist. Some of the low temperature reactions are not accessible in continuous cooling experiments and require isothermal studies.

  9. Low-Temperature Mechanical Behavior of Super Duplex Stainless Steel with Sigma Precipitation

    OpenAIRE

    Kim, Seul-Kee; Kang, Ki-Yeob; Kim, Myung-Soo; Lee, Jae-Myung

    2015-01-01

    Experimental studies in various aspects have to be conducted to maintain stable applications of super duplex stainless steels (SDSS) because the occurrence rate of sigma phase, variable temperature and growth direction of sigma phase can influence mechanical performances of SDSS. Tensile tests of precipitated SDSS were performed under various temperatures to analyze mechanical and morphological behavior.

  10. Low-Temperature Mechanical Behavior of Super Duplex Stainless Steel with Sigma Precipitation

    Directory of Open Access Journals (Sweden)

    Seul-Kee Kim

    2015-09-01

    Full Text Available Experimental studies in various aspects have to be conducted to maintain stable applications of super duplex stainless steels (SDSS because the occurrence rate of sigma phase, variable temperature and growth direction of sigma phase can influence mechanical performances of SDSS. Tensile tests of precipitated SDSS were performed under various temperatures to analyze mechanical and morphological behavior.

  11. Creep and precipitation behaviors of AL6XN austenitic steel at elevated temperatures

    Science.gov (United States)

    Meng, L. J.; Sun, J.; Xing, H.

    2012-08-01

    Creep behaviors of the solution-treated AL6XN austenitic stainless steel have been investigated at 873-1023 K and 120-260 MPa. The results showed that the creep stress exponent and activation energy of the AL6XN steel are 5 and 395.4 kJ/mol, respectively in the power-law breakdown regime. TEM observations revealed that dislocations distributed homogenously in grains. The creep deformation mechanism is mainly attributed to viscous dislocation glide. Precipitates in the steel after creep deformation were additionally analyzed by TEM, and the results showed that there are four different types of precipitates, such as M23C6, M6C, σ phase and Laves phase. The M23C6 carbides were observed at grain boundaries in the steel after creep at 873 K. The M6C, σ phase and Laves phase precipitates were found when the creep temperature increases to 923-1023 K. Although the AL6XN steel exhibited low steady state creep rates, a high volume fraction of brittle precipitates of σ and Laves phases reduced the creep lifetime of the steel at elevated temperatures.

  12. Creep and precipitation behaviors of AL6XN austenitic steel at elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Meng, L.J. [School of Materials Science and Engineering, Shanghai Jiaotong University, Dongchuan Road 800, Shanghai 200240 (China); Sun, J., E-mail: jsun@sjtu.edu.cn [School of Materials Science and Engineering, Shanghai Jiaotong University, Dongchuan Road 800, Shanghai 200240 (China); Xing, H. [School of Materials Science and Engineering, Shanghai Jiaotong University, Dongchuan Road 800, Shanghai 200240 (China)

    2012-08-15

    Creep behaviors of the solution-treated AL6XN austenitic stainless steel have been investigated at 873-1023 K and 120-260 MPa. The results showed that the creep stress exponent and activation energy of the AL6XN steel are 5 and 395.4 kJ/mol, respectively in the power-law breakdown regime. TEM observations revealed that dislocations distributed homogenously in grains. The creep deformation mechanism is mainly attributed to viscous dislocation glide. Precipitates in the steel after creep deformation were additionally analyzed by TEM, and the results showed that there are four different types of precipitates, such as M{sub 23}C{sub 6}, M{sub 6}C, {sigma} phase and Laves phase. The M{sub 23}C{sub 6} carbides were observed at grain boundaries in the steel after creep at 873 K. The M{sub 6}C, {sigma} phase and Laves phase precipitates were found when the creep temperature increases to 923-1023 K. Although the AL6XN steel exhibited low steady state creep rates, a high volume fraction of brittle precipitates of {sigma} and Laves phases reduced the creep lifetime of the steel at elevated temperatures.

  13. CHARACTERISTICS OF MEI-YU PRECIPITATION AND SVD ANALYSIS OF PRECIPITATION OVER THE YANGTZE-HUAIHE RIVERS VALLEYS AND THE SEA SURFACE TEMPERATURE IN THE NORTHERN PACIFIC OCEAN

    Institute of Scientific and Technical Information of China (English)

    MAO Wen-shu; WANG Qian-qian; PENG Jun; LI Yong-hua

    2008-01-01

    Based on the precipitation data of Meiyu at 37 stations in the valleys of Yangtze and Huaihe Rivers from 1954 to 2001, the temporal-spatial characteristics of Meiyu precipitation and their relationships with the sea surface temperature in northern Pacific are investigated using such methods as harmonic analysis, empirical orthogonal function (EOF), composite analysis and singular value decomposition (SVD). The results show that the temporal evolution and spatial distribution of Meiyu precipitation are not homogeneous in the Yangtze-Huaihe Rivers basins but with prominent inter-annual and inter-decadal variabilities. The key region between the anomalies of Meiyu precipitation and the monthly sea surface temperature anomalies (SSTA) lies in the west wind drift of North Pacific, which influences the precipitation anomaly of Meiyu precipitation over a key period of time from January to March in the same year. When the SST in the North Pacific west wind drift is warmer (colder) than average during these months, Meiyu precipitation anomalously increases (decreases) in the concurrent year. Results of SVD are consistent with those of composite analysis which pass the significance test of Monte-Carlo at 0.05.

  14. Independent effects of temperature and precipitation on modeled runoff in the conterminous United States

    Science.gov (United States)

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

    2011-01-01

    A water-balance model is used to simulate time series of water-year runoff for 4 km ?? 4 km grid cells for the conterminous United States during the 1900-2008 period. Model outputs are used to examine the separate effects of precipitation and temperature on runoff variability. Overall, water-year runoff has increased in the conterminous United States and precipitation has accounted for almost all of the variability in water-year runoff during the past century. In contrast, temperature effects on runoff have been small for most locations in the United States even during periods when temperatures for most of the United States increased significantly. Copyright 2011 by the American Geophysical Union.

  15. Bivariate return periods of temperature and precipitation explain a large fraction of European crop yields

    Science.gov (United States)

    Zscheischler, Jakob; Orth, Rene; Seneviratne, Sonia I.

    2017-07-01

    Crops are vital for human society. Crop yields vary with climate and it is important to understand how climate and crop yields are linked to ensure future food security. Temperature and precipitation are among the key driving factors of crop yield variability. Previous studies have investigated mostly linear relationships between temperature and precipitation and crop yield variability. Other research has highlighted the adverse impacts of climate extremes, such as drought and heat waves, on crop yields. Impacts are, however, often non-linearly related to multivariate climate conditions. Here we derive bivariate return periods of climate conditions as indicators for climate variability along different temperature-precipitation gradients. We show that in Europe, linear models based on bivariate return periods of specific climate conditions explain on average significantly more crop yield variability (42 %) than models relying directly on temperature and precipitation as predictors (36 %). Our results demonstrate that most often crop yields increase along a gradient from hot and dry to cold and wet conditions, with lower yields associated with hot and dry periods. The majority of crops are most sensitive to climate conditions in summer and to maximum temperatures. The use of bivariate return periods allows the integration of non-linear impacts into climate-crop yield analysis. This offers new avenues to study the link between climate and crop yield variability and suggests that they are possibly more strongly related than what is inferred from conventional linear models.

  16. Room temperature ductility of NiAl-strengthened ferritic steels: Effects of precipitate microstructure

    International Nuclear Information System (INIS)

    Teng, Z.K.; Liu, C.T.; Miller, M.K.; Ghosh, G.; Kenik, E.A.; Huang, S.; Liaw, P.K.

    2012-01-01

    Highlights: ► Effects of precipitate microstructure on the ductility were investigated. ► The NiAl precipitates can be systematically characterized by TEM, APT, and USAXS. ► Ductility is a function of the precipitate volume fraction. ► Ductility is closely related to the Al and Ni solubilities in the Fe matrix. ► Ductility is independent of precipitate size and inter-particle spacing. - Abstract: The effects of precipitate microstructure on the room temperature ductility of a series of carefully designed Fe–Al–Ni–Cr–Mo steels were investigated. Transmission electron microscopy (TEM), ultra small angle X-ray scattering (USAXS), and atom probe tomography (APT) were conducted to quantify the nano-scaled precipitates. The accuracy of the characterization results was verified by a numerical analysis. Three point bending tests results demonstrated that ductility was a function of the precipitate volume fraction and the Al and Ni concentrations in the Fe matrix, these relationships were discussed in terms of possible mechanisms. The ductility was also found to be independent of the precipitate size and inter-particle spacing in the studied range, which was validated by a theoretical model.

  17. Tracing temperature patterns of cut leafy greens during service in North Carolina school food service.

    Science.gov (United States)

    Thomas, Ellen M; Chapman, Benjamin; Jaykus, Lee-Ann; Phister, Trevor

    2014-09-01

    Contaminated fresh produce has been increasingly identified as a cause of foodborne illnesses. Because of concerns about pathogen growth on these food items at retail, the 2009 U.S. Food and Drug Administration Food Code established that cut leafy greens (lettuce, spinach, spring mix, cabbage, arugula, and kale) must have time and temperature controls for safety and hence should be kept at refrigerated temperatures (5°C or lower). The purpose of this study was to determine the temperature profiles of cut leafy greens in single-serving clamshell containers provided as part of the North Carolina School Lunch Program and to compare the two policies that North Carolina has in place to control the temperature of these products (the 3-day rule and time in lieu of temperature). Temperatures were recorded with data loggers in 24 schools during a 3-day period. In all cases, substantial temperature variability was found for these products, including temperatures above 5°C for at least 1 h on each of the 3 days. In some cases, temperatures reached above 5°C for more than 3 h throughout the serving time. The results demonstrate the importance of developing a protocol for continuous temperature monitoring of leafy greens served in school lunch programs.

  18. Soil response to long-term projections of extreme temperature and precipitation in the southern La Plata Basin

    Science.gov (United States)

    Pántano, Vanesa C.; Penalba, Olga C.

    2017-12-01

    Projected changes were estimated considering the main variables which take part in soil-atmosphere interaction. The analysis was focused on the potential impact of these changes on soil hydric condition under extreme precipitation and evapotranspiration, using the combination of Global Climate Models (GCMs) and observational data. The region of study is the southern La Plata Basin that covers part of Argentine territory, where rainfed agriculture production is one of the most important economic activities. Monthly precipitation and maximum and minimum temperatures were used from high quality-controlled observed data from 46 meteorological stations and the ensemble of seven CMIP5 GCMs in two periods: 1970-2005 and 2065-2100. Projected changes in monthly effective temperature and precipitation were analysed. These changes were combined with observed series for each probabilistic interval. The result was used as input variables for the water balance model in order to obtain consequent soil hydric condition (deficit or excess). Effective temperature and precipitation are expected to increase according to the projections of GCMs, with few exceptions. The analysis revealed increase (decrease) in the prevalence of evapotranspiration over precipitation, during spring (winter). Projections for autumn months show precipitation higher than potential evapotranspiration more frequently. Under dry extremes, the analysis revealed higher projected deficit conditions, impacting on crop development. On the other hand, under wet extremes, excess would reach higher values only in particular months. During December, projected increase in temperatures reduces the impact of extreme high precipitation but favours deficit conditions, affecting flower-fructification stage of summer crops.

  19. Strengthening of stainless steel weldment by high temperature precipitation

    Directory of Open Access Journals (Sweden)

    Sergio Neves Monteiro

    2017-10-01

    Full Text Available The mechanical behavior and the strengthening mechanism of stainless steel welded joints at 600 °C have been investigated. The welds were composed of AISI 304 stainless steel, as base metal, and niobium containing AISI 347 stainless steel, as weld metal. The investigation was conducted by means of creep tests. The welded specimens were subjected to both high temperature (600 °C and long periods (up to 2000 h under constant load, and both mechanical properties and microstructural changes in the material were monitored. It was found that the exposure of the material at 600 °C under load contributes to a strengthening effect on the weld. The phenomenon might be correlated with an accelerated process of second phase precipitation hardening. Keywords: Stainless steel, Weld, AISI 304, Precipitation hardening

  20. Precipitates/Salts Model Calculations for Various Drift Temperature Environments

    International Nuclear Information System (INIS)

    Marnier, P.

    2001-01-01

    The objective and scope of this calculation is to assist Performance Assessment Operations and the Engineered Barrier System (EBS) Department in modeling the geochemical effects of evaporation within a repository drift. This work is developed and documented using procedure AP-3.12Q, Calculations, in support of ''Technical Work Plan For Engineered Barrier System Department Modeling and Testing FY 02 Work Activities'' (BSC 2001a). The primary objective of this calculation is to predict the effects of evaporation on the abstracted water compositions established in ''EBS Incoming Water and Gas Composition Abstraction Calculations for Different Drift Temperature Environments'' (BSC 2001c). A secondary objective is to predict evaporation effects on observed Yucca Mountain waters for subsequent cement interaction calculations (BSC 2001d). The Precipitates/Salts model is documented in an Analysis/Model Report (AMR), ''In-Drift Precipitates/Salts Analysis'' (BSC 2001b)

  1. Relation between Euclidean and real time calculations of Green functions at finite temperature

    International Nuclear Information System (INIS)

    Bochkarev, A.

    1993-01-01

    We find a relation between the semiclassical approximation of the temperature (Matsubara) two-point correlator and the corresponding classical Green function in real time at finite temperature. The anharmonic oscillator at finite temperature is used to illustrate our statement, which is however of rather general origin

  2. Evolution of precipitate in nickel-base alloy 718 irradiated with argon ions at elevated temperature

    International Nuclear Information System (INIS)

    Jin, Shuoxue; Luo, Fengfeng; Ma, Shuli; Chen, Jihong; Li, Tiecheng; Tang, Rui; Guo, Liping

    2013-01-01

    Alloy 718 is a nickel-base superalloy whose strength derives from γ′(Ni 3 (Al,Ti)) and γ″(Ni 3 Nb) precipitates. The evolution of the precipitates in alloy 718 irradiated with argon ions at elevated temperature were examined via transmission electron microscopy. Selected-area electron diffraction indicated superlattice spots disappeared after argon ion irradiation, which showing that the ordered structure of the γ′ and γ″ precipitates became disordered. The size of the precipitates became smaller with the irradiation dose increasing at 290 °C

  3. Bivariate spatial analysis of temperature and precipitation from general circulation models and observation proxies

    KAUST Repository

    Philbin, R.

    2015-05-22

    This study validates the near-surface temperature and precipitation output from decadal runs of eight atmospheric ocean general circulation models (AOGCMs) against observational proxy data from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis temperatures and Global Precipitation Climatology Project (GPCP) precipitation data. We model the joint distribution of these two fields with a parsimonious bivariate Matérn spatial covariance model, accounting for the two fields\\' spatial cross-correlation as well as their own smoothnesses. We fit output from each AOGCM (30-year seasonal averages from 1981 to 2010) to a statistical model on each of 21 land regions. Both variance and smoothness values agree for both fields over all latitude bands except southern mid-latitudes. Our results imply that temperature fields have smaller smoothness coefficients than precipitation fields, while both have decreasing smoothness coefficients with increasing latitude. Models predict fields with smaller smoothness coefficients than observational proxy data for the tropics. The estimated spatial cross-correlations of these two fields, however, are quite different for most GCMs in mid-latitudes. Model correlation estimates agree well with those for observational proxy data for Australia, at high northern latitudes across North America, Europe and Asia, as well as across the Sahara, India, and Southeast Asia, but elsewhere, little consistent agreement exists.

  4. Bivariate spatial analysis of temperature and precipitation from general circulation models and observation proxies

    KAUST Repository

    Philbin, R.; Jun, M.

    2015-01-01

    This study validates the near-surface temperature and precipitation output from decadal runs of eight atmospheric ocean general circulation models (AOGCMs) against observational proxy data from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis temperatures and Global Precipitation Climatology Project (GPCP) precipitation data. We model the joint distribution of these two fields with a parsimonious bivariate Matérn spatial covariance model, accounting for the two fields' spatial cross-correlation as well as their own smoothnesses. We fit output from each AOGCM (30-year seasonal averages from 1981 to 2010) to a statistical model on each of 21 land regions. Both variance and smoothness values agree for both fields over all latitude bands except southern mid-latitudes. Our results imply that temperature fields have smaller smoothness coefficients than precipitation fields, while both have decreasing smoothness coefficients with increasing latitude. Models predict fields with smaller smoothness coefficients than observational proxy data for the tropics. The estimated spatial cross-correlations of these two fields, however, are quite different for most GCMs in mid-latitudes. Model correlation estimates agree well with those for observational proxy data for Australia, at high northern latitudes across North America, Europe and Asia, as well as across the Sahara, India, and Southeast Asia, but elsewhere, little consistent agreement exists.

  5. Decadal Seasonal Shifts of Precipitation and Temperature in TRMM and AIRS Data

    Science.gov (United States)

    Savtchenko, Andrey; Huffman, George; Meyer, David; Vollmer, Bruce

    2018-01-01

    We present results from an analysis of seasonal phase shifts in the global precipitation and surface temperatures. We use data from the TRMM (Tropical Rainfall Measuring Mission) Multi-satellite Precipitation Algorithm (TMPA), and the Atmospheric Infrared Sounder (AIRS) on Aqua satellite, all hosted at NASA Goddard Earth Science Data and Information Services Center (GES DISC). We explore the information content and data usability by first aggregating daily grids from the entire records of both missions to pentad (5-day) series which are then processed using Singular Value Decomposition approach. A strength of this approach is the normalized principal components that can then be easily converted from real to complex time series. Thus, we can separate the most informative, the seasonal, components and analyze unambiguously for potential seasonal phase drifts. TMPA and AIRS records represent correspondingly 20 and 15 years of data, which allows us to run simple “phase learning†from the first 5 years of records and use it as reference. The most recent 5 years are then phase-compared with the reference. We demonstrate that the seasonal phase of global precipitation and surface temperatures has been stable in the past two decades. However, a small global trend of delayed precipitation, and earlier arrival of surface temperatures seasons, are detectable at 95% confidence level. Larger phase shifts are detectable at regional level, in regions recognizable from the Eigen vectors to having strong seasonal patterns. For instance, in Central North America, including the North American Monsoon region, confident phase shifts of 1-2 days per decade are detected at 95% confidence level. While seemingly symbolic, these shifts are indicative of larger changes in the Earth Climate System. We thus also demonstrate a potential usability scenario of Earth Science Data Records curated at the NASA GES DISC in partnership with Earth Science Missions.

  6. Soil moisture effects on seasonal temperature and precipitation forecast scores in Europe

    Energy Technology Data Exchange (ETDEWEB)

    Hurk, Bart van den; Camargo, Helio [Royal Netherlands Meteorological Institute, KNMI, PO Box 201, AE De Bilt (Netherlands); Doblas-Reyes, Francisco [Catalan Institute of Climate Sciences (IC3), Barcelona (Spain); European Centre for Medium-range Weather Forecasts (ECMWF), Reading (United Kingdom); Balsamo, Gianpaolo [European Centre for Medium-range Weather Forecasts (ECMWF), Reading (United Kingdom); Koster, Randal D. [NASA/Goddard Space Flight Center, Global Modeling and Assimilation Office, Greenbelt, MD (United States); Seneviratne, Sonia I. [Institute for Atmospheric and Climate Science, Zurich (Switzerland)

    2012-01-15

    The Second Global Land Atmosphere Coupling Experiment (GLACE2) is designed to explore the improvement of forecast skill of summertime temperature and precipitation up to 8 weeks ahead by using realistic soil moisture initialization. For the European continent, we show in this study that for temperature the skill does indeed increase up to 6 weeks, but areas with (statistically significant) lower skill also exist at longer lead times. The skill improvement is smaller than shown earlier for the US, partly because of a lower potential predictability of the European climate at seasonal time scales. Selection of extreme soil moisture conditions or a subset of models with similar initial soil moisture conditions does improve the forecast skill, and sporadic positive effects are also demonstrated for precipitation. Using realistic initial soil moisture data increases the interannual variability of temperature compared to the control simulations in the South-Central European area at longer lead times. This leads to better temperature forecasts in a remote area in Western Europe. However, the covered range of forecast dates (1986-1995) is too short to isolate a clear physical mechanism for this remote correlation. (orig.)

  7. Assessment of green roof systems in terms of water and energy balance

    Directory of Open Access Journals (Sweden)

    Mert Ekşi

    2016-01-01

    Full Text Available Green roofs concept term is used for extensive green roofs which are planted with herbaceous plants that can be adapted into changeable environmental conditions on a shallow substrate layer, require minimal maintenance, installed for their benefits to building and urban scale. Main objective of this study is to determine the characteristics of a green roof such as thermal insulation, water holding capacity, runoff characteristics, plant growth and its interaction with environmental factors in Istanbul climate conditions by performing comparative measurements. In this study, a research site (IU Green Roof Research Station was founded to assess water and energy balance of green roofs. Thus, a typical green roof was evaluated in terms of water and energy balance and its interaction with the building and city was determined. energy efficiency of green roof system was 77% higher than reference roof. Temperature fluctuations on green roof section of the roof were 79% lower. In addition, green roof retained 12,8% - 100% of precipitation and delayed runoff up to 23 hours depending on water content of substrate.

  8. On the Precipitation and Precipitation Change in Alaska

    Directory of Open Access Journals (Sweden)

    Gerd Wendler

    2017-12-01

    Full Text Available Alaska observes very large differences in precipitation throughout the state; southeast Alaska experiences consistently wet conditions, while northern Arctic Alaska observes very dry conditions. The maximum mean annual precipitation of 5727 mm is observed in the southeastern panhandle at Little Port Arthur, while the minimum of 92 mm occurs on the North Slope at Kuparuk. Besides explaining these large differences due to geographic and orographic location, we discuss the changes in precipitation with time. Analyzing the 18 first-order National Weather Service stations, we found that the total average precipitation in the state increased by 17% over the last 67 years. The observed changes in precipitation are furthermore discussed as a function of the observed temperature increase of 2.1 °C, the mean temperature change of the 18 stations over the same period. This observed warming of Alaska is about three times the magnitude of the mean global warming and allows the air to hold more water vapor. Furthermore, we discuss the effect of the Pacific Decadal Oscillation (PDO, which has a strong influence on both the temperature and precipitation in Alaska.

  9. Precipitation, temperature and wind in Norway: dynamical downscaling of ERA40

    Energy Technology Data Exchange (ETDEWEB)

    Barstad, I.; Sorteberg, A.; Flatoey, F. [Bjerknes Centre for Climate Research, Bergen (Norway); Deque, M. [Meteo France, EAC/GMGEC/CNRM, Toulouse (France)

    2009-11-15

    A novel downscaling approach of the ERA40 (ECMWF 40-years reanalysis) data set has been taken and results for comparison with observations in Norway are shown. The method applies a nudging technique in a stretched global model, focused in the Norwegian Sea (67 N, 5 W). The effective resolution is three times the one of the ERA40, equivalent to about 30 km grid spacing in the area of focus. Longer waves (precipitation. The comparison to observations incorporate numerous station data points of (1) precipitation (357), (2) temperature (98) and (3) wind (10), and for the period 1961-1990, the downscaled data set shows large improvements over ERA40. The daily precipitation shows considerable reduction in bias (from 50 to 11%), and twofold reduction at the 99.9 percentile (from -59 to -29%). The daily temperature showed a bias reduction of about a degree in most areas, and relative large RMSE reduction (from 7.5 to 5.0 C except winter). The wind comparison showed a slight improvement in bias, and significant improvements in RMSE. (orig.)

  10. Analysis of High Temperature Deformed Structure and Dynamic Precipitation in W9Mo3Cr4V Steel

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    With TEM、SEM, various high-temperature deformed structures inW9Mo3Cr4V steel were investigated. The sub-structures,recrystallized nuclei, as well as the dynamic precipitation were also studied and analyzed. The relationship between recrystallized structures and dynamic precipitation was discussed. The results showed that the deformed structures in W9Mo3Cr4V steel are more complicated than those in low alloy steels. Because W9Mo3Cr4V steel is a high-speed steel, there are a large number of residual carbides on the matrix. Also, much dynamic precipitating carbides will precipitate during deformation at high temperature.

  11. Covariability of Central America/Mexico winter precipitation and tropical sea surface temperatures

    Science.gov (United States)

    Pan, Yutong; Zeng, Ning; Mariotti, Annarita; Wang, Hui; Kumar, Arun; Sánchez, René Lobato; Jha, Bhaskar

    2018-06-01

    In this study, the relationships between Central America/Mexico (CAM) winter precipitation and tropical Pacific/Atlantic sea surface temperatures (SSTs) are examined based on 68-year (1948-2015) observations and 59-year (1957-2015) atmospheric model simulations forced by observed SSTs. The covariability of the winter precipitation and SSTs is quantified using the singular value decomposition (SVD) method with observational data. The first SVD mode relates out-of-phase precipitation anomalies in northern Mexico and Central America to the tropical Pacific El Niño/La Niña SST variation. The second mode links a decreasing trend in the precipitation over Central America to the warming of SSTs in the tropical Atlantic, as well as in the tropical western Pacific and the tropical Indian Ocean. The first mode represents 67% of the covariance between the two fields, indicating a strong association between CAM winter precipitation and El Niño/La Niña, whereas the second mode represents 20% of the covariance. The two modes account for 32% of CAM winter precipitation variance, of which, 17% is related to the El Niño/La Niña SST and 15% is related to the SST warming trend. The atmospheric circulation patterns, including 500-hPa height and low-level winds obtained by linear regressions against the SVD SST time series, are dynamically consistent with the precipitation anomaly patterns. The model simulations driven by the observed SSTs suggest that these precipitation anomalies are likely a response to tropical SST forcing. It is also shown that there is significant potential predictability of CAM winter precipitation given tropical SST information.

  12. Influence of temperature, precipitation, and cultivar characteristics on changes in the spectrum of pathogenic fungi in winter wheat.

    Science.gov (United States)

    Hýsek, Josef; Vavera, Radek; Růžek, Pavel

    2017-06-01

    In view of the threat posed by climate change, we studied the influence of temperature, precipitation, cultivar characteristics, and technical management measures on the occurrence of phytopathogenic fungi in wheat during 2009-2013. This work involved experiments at two sites differing in average temperatures and precipitation. Temperature and precipitation appear to influence differences in the spectrum of phytopathogenic fungi at the individual sites. In 2009 (the warmest year), Alternaria triticina was dominant. In 2010 (having the smallest deviations from the average for individual years), Septoria tritici dominated. In 2011, Puccinia triticina was most prominent, while in 2012, the genus Drechslera (Pyrenophora) and in 2013, S. tritici and Drechslera tritici-repentis (DTR) dominated. Temperature and precipitation levels in the individual spring months (warmer March to May) played a large role, especially for the leaf rust P. triticina in 2011. A change of only 1 °C with different precipitation during a year played a significant role in changing wheat's fungal spectrum. Cluster analysis showed the differences between single pathogenic fungi on wheat in a single year due to temperature and precipitation. Alternaria abundance was strongly influenced by year (p < 0.001) while locality was significant only in certain years (2012, 2013; p = 0.004 and 0.015, respectively). The same factors were revealed to be significant in the case of Puccinia, but locality played a role (p < 0.001) in different years (2011, 2013). The abundance of S. tritici and Pyrenophora tritici-repentis (Drechslera tritici-repentis) was influenced only by year (p < 0.001).

  13. On the relationship between the snowflake type aloft and the surface precipitation types at temperatures near 0 °C

    Science.gov (United States)

    Sankaré, Housseyni; Thériault, Julie M.

    2016-11-01

    Winter precipitation types can have major consequences on power outages, road conditions and air transportation. The type of precipitation reaching the surface depends strongly on the vertical temperature of the atmosphere, which is often composed of a warm layer aloft and a refreezing layer below it. A small variation of the vertical structure can lead to a change in the type of precipitation near the surface. It has been shown in previous studies that the type of precipitation depends also on the precipitation rate, which is directly linked to the particle size distribution and that a difference as low as 0.5 °C in the vertical temperature profile could change the type of precipitation near the surface. Given the importance of better understanding the formation of winter precipitation type, the goal of this study is to assess the impact of the snowflake habit aloft on the type of precipitation reaching the surface when the vertical temperature is near 0 °C. To address this, a one dimensional cloud model coupled with a bulk microphysics scheme was used. Four snowflake types (dendrite, bullet, column and graupel) have been added to the scheme. The production of precipitation at the surface from these types of snow has been compared to available observations. The results showed that the thickness of the snow-rain transition is four times deeper when columns and graupel only fall through the atmosphere compared to dendrites. Furthermore, a temperature of the melting layer that is three (four) times warmer is required to completely melt columns and graupel (dendrites). Finally, the formation of freezing rain is associated with the presence of lower density snowflakes (dendrites) aloft compared to the production of ice pellets (columns). Overall, this study demonstrated that the type of snowflakes has an impact on the type of precipitation reaching the surface when the temperature is near 0 °C.

  14. Arctic daily temperature and precipitation extremes: Observed and simulated physical behavior

    Science.gov (United States)

    Glisan, Justin Michael

    Simulations using a six-member ensemble of Pan-Arctic WRF (PAW) were produced on two Arctic domains with 50-km resolution to analyze precipitation and temperature extremes for various periods. The first study used a domain developed for the Regional Arctic Climate Model (RACM). Initial simulations revealed deep atmospheric circulation biases over the northern Pacific Ocean, manifested in pressure, geopotential height, and temperature fields. Possible remedies to correct these large biases, such as modifying the physical domain or using different initial/boundary conditions, were unsuccessful. Spectral (interior) nudging was introduced as a way of constraining the model to be more consistent with observed behavior. However, such control over numerical model behavior raises concerns over how much nudging may affect unforced variability and extremes. Strong nudging may reduce or filter out extreme events, since the nudging pushes the model toward a relatively smooth, large-scale state. The question then becomes---what is the minimum spectral nudging needed to correct biases while not limiting the simulation of extreme events? To determine this, we use varying degrees of spectral nudging, using WRF's standard nudging as a reference point during January and July 2007. Results suggest that there is a marked lack of sensitivity to varying degrees of nudging. Moreover, given that nudging is an artificial forcing applied in the model, an important outcome of this work is that nudging strength apparently can be considerably smaller than WRF's standard strength and still produce reliable simulations. In the remaining studies, we used the same PAW setup to analyze daily precipitation extremes simulated over a 19-year period on the CORDEX Arctic domain for winter and summer. We defined these seasons as the three-month period leading up to and including the climatological sea ice maximum and minimum, respectively. Analysis focused on four North American regions defined using

  15. Carbon isotopes of C3 herbs correlate with temperature on removing the influence of precipitation across a temperature transect in the agro-pastoral ecotone of northern China.

    Science.gov (United States)

    Liu, Xian-Zhao; Zhang, Yong; Li, Zhen-Guo; Feng, Teng; Su, Qing; Song, Yan

    2017-12-01

    Plant δ 13 C-temperature (δ-T) relation has been established in many systems and is often used as paleotemperature transfer function. However, it is still unclear about the exact contributions of temperature variation to plant 13 C discrimination because of covariation between temperature and precipitation (aridity), which reduces confidence in reconstruction of paleoclimate. In this study, we measured carbon isotope composition (δ 13 C) of 173 samples of C3 perennial herbs from 22 sites across a temperature gradient along the 400 mm isohyet in the farming-pastoral zone of North China. The results showed that precipitation obviously affected the correlations of temperatures and foliar δ 13 C. After removing the influence of precipitation by analysis of covariance (ANCOVA), a more strongly positive relationship was obtained between site-mean foliar δ 13 C and annual mean temperature (AMT), with a regression coefficient of 0.1636‰/°C ( p  =   .0024). For widespread species, Artemisia lavandulaefolia and Artemisia capillaries , the slopes (or coefficients) of foliar δ 13 C and AMT were significantly steeper (larger) than those of foliar δ 13 C and AMT where the precipitation influence was not excluded, whereas the δ-T coefficients of Polygonum persicaria and Leymus chinensis showed little change across the transect after deducting the precipitation effect. Moreover, the positive relationship between temperature and δ 13 C over the transect could be explained by soil moisture availability related to temperature. Our results may afford new opportunities for investigating the nature of past climate variability.

  16. Precipitates/Salts Model Calculations for Various Drift Temperature Environments

    Energy Technology Data Exchange (ETDEWEB)

    P. Marnier

    2001-12-20

    The objective and scope of this calculation is to assist Performance Assessment Operations and the Engineered Barrier System (EBS) Department in modeling the geochemical effects of evaporation within a repository drift. This work is developed and documented using procedure AP-3.12Q, Calculations, in support of ''Technical Work Plan For Engineered Barrier System Department Modeling and Testing FY 02 Work Activities'' (BSC 2001a). The primary objective of this calculation is to predict the effects of evaporation on the abstracted water compositions established in ''EBS Incoming Water and Gas Composition Abstraction Calculations for Different Drift Temperature Environments'' (BSC 2001c). A secondary objective is to predict evaporation effects on observed Yucca Mountain waters for subsequent cement interaction calculations (BSC 2001d). The Precipitates/Salts model is documented in an Analysis/Model Report (AMR), ''In-Drift Precipitates/Salts Analysis'' (BSC 2001b).

  17. Estimation of precipitable water from surface dew point temperature

    International Nuclear Information System (INIS)

    Abdel Wahab, M.; Sharif, T.A.

    1991-09-01

    The Reitan (1963) regression equation which is of the form lnw=a+bT d has been examined and tested to estimate precipitable water content from surface dew point temperature at different locations. The study confirms that the slope of this equation (b) remains constant at the value of .0681 deg. C., while the intercept (a) changes rapidly with the latitude. The use of the variable intercept can improve the estimated result by 2%. (author). 6 refs, 4 figs, 3 tabs

  18. Performance of the general circulation models in simulating temperature and precipitation over Iran

    Science.gov (United States)

    Abbasian, Mohammadsadegh; Moghim, Sanaz; Abrishamchi, Ahmad

    2018-03-01

    General Circulation Models (GCMs) are advanced tools for impact assessment and climate change studies. Previous studies show that the performance of the GCMs in simulating climate variables varies significantly over different regions. This study intends to evaluate the performance of the Coupled Model Intercomparison Project phase 5 (CMIP5) GCMs in simulating temperature and precipitation over Iran. Simulations from 37 GCMs and observations from the Climatic Research Unit (CRU) were obtained for the period of 1901-2005. Six measures of performance including mean bias, root mean square error (RMSE), Nash-Sutcliffe efficiency (NSE), linear correlation coefficient (r), Kolmogorov-Smirnov statistic (KS), Sen's slope estimator, and the Taylor diagram are used for the evaluation. GCMs are ranked based on each statistic at seasonal and annual time scales. Results show that most GCMs perform reasonably well in simulating the annual and seasonal temperature over Iran. The majority of the GCMs have a poor skill to simulate precipitation, particularly at seasonal scale. Based on the results, the best GCMs to represent temperature and precipitation simulations over Iran are the CMCC-CMS (Euro-Mediterranean Center on Climate Change) and the MRI-CGCM3 (Meteorological Research Institute), respectively. The results are valuable for climate and hydrometeorological studies and can help water resources planners and managers to choose the proper GCM based on their criteria.

  19. Satellite view of seasonal greenness trends and controls in South Asia

    Science.gov (United States)

    Sarmah, Sangeeta; Jia, Gensuo; Zhang, Anzhi

    2018-03-01

    South Asia (SA) has been considered one of the most remarkable regions for changing vegetation greenness, accompanying its major expansion of agricultural activities, especially irrigated farming. The influence of the monsoon climate on the seasonal trends and anomalies of vegetation greenness is poorly understood in this area. Herein, we used the satellite-based Normalized Difference Vegetation Index (NDVI) to investigate various spatiotemporal patterns in vegetation activity during summer and winter monsoon (SM and WM) seasons and among irrigated croplands (IC), rainfed croplands (RC), and natural vegetation (NV) areas during 1982–2013. Seasonal NDVI variations with climatic factors (precipitation and temperature) and land use and cover changes (LUCC) have also been investigated. This study demonstrates that the seasonal dynamics of vegetation could improve the detailed understanding of vegetation productivity over the region. We found distinct greenness trends between two monsoon seasons and among the major land use/cover classes. Winter monsoons contributed greater variability to the overall vegetation dynamics of SA. Major greening occurred due to the increased productivity over irrigated croplands during the winter monsoon season; meanwhile, browning trends were prominent over NV areas during the same season. Maximum temperatures had been increasing tremendously during the WM season; however, the precipitation trend was not significant over SA. Both the climate variability and LUCC revealed coupled effects on the long term NDVI trends in NV areas, especially in the hilly regions, whereas anthropogenic activities (agricultural advancements) played a pivotal role in the rest of the area. Until now, advanced cultivation techniques have proven to be beneficial for the region in terms of the productivity of croplands. However, the crop productivity is at risk under climate change.

  20. Effect of carbide precipitates on high temperature creep of a 20Cr-25Ni austenitic stainless steel

    International Nuclear Information System (INIS)

    Yamane, T.; Takahashi, Y.; Nakagawa, K.

    1984-01-01

    The high temperature creep of an austenitic stainless steel having carbide precipitates, is different from that of the carbide precipitate-free one. Strain rates of the steady state creep d(epsilonsub(s))/dt, or minimum strain rates of the creep in precipitate hardened and dispersion strengthened alloys at the creep temperature T, can be expressed by Sherby-Dorn's equation d(epsilonsub(s))/dt = Aσsup(n) exp (-Qsub(c)/RT). The stress exponent n, and the activation energy for creep Qsub(c), in a power law creep region, are more than those of unstrengthened alloys, where σ is the creep stress, R the gas constant and A the constant. In this research, the influence of carbide precipitates on steady creep rates, is investigated. Experimental details are given. Results are given and discussed. (author)

  1. Predictability of monthly temperature and precipitation using automatic time series forecasting methods

    Science.gov (United States)

    Papacharalampous, Georgia; Tyralis, Hristos; Koutsoyiannis, Demetris

    2018-02-01

    We investigate the predictability of monthly temperature and precipitation by applying automatic univariate time series forecasting methods to a sample of 985 40-year-long monthly temperature and 1552 40-year-long monthly precipitation time series. The methods include a naïve one based on the monthly values of the last year, as well as the random walk (with drift), AutoRegressive Fractionally Integrated Moving Average (ARFIMA), exponential smoothing state-space model with Box-Cox transformation, ARMA errors, Trend and Seasonal components (BATS), simple exponential smoothing, Theta and Prophet methods. Prophet is a recently introduced model inspired by the nature of time series forecasted at Facebook and has not been applied to hydrometeorological time series before, while the use of random walk, BATS, simple exponential smoothing and Theta is rare in hydrology. The methods are tested in performing multi-step ahead forecasts for the last 48 months of the data. We further investigate how different choices of handling the seasonality and non-normality affect the performance of the models. The results indicate that: (a) all the examined methods apart from the naïve and random walk ones are accurate enough to be used in long-term applications; (b) monthly temperature and precipitation can be forecasted to a level of accuracy which can barely be improved using other methods; (c) the externally applied classical seasonal decomposition results mostly in better forecasts compared to the automatic seasonal decomposition used by the BATS and Prophet methods; and (d) Prophet is competitive, especially when it is combined with externally applied classical seasonal decomposition.

  2. Effect of Temperature on Precipitation Rate of Calcium Carbonate Produced through Microbial Metabolic Process of Bio Materials

    Directory of Open Access Journals (Sweden)

    Prima Yane Putri

    2016-09-01

    Full Text Available Concrete is the most widely used construction material in civil engineering. But plain concrete is a brittle material and has little resistance to cracking. The cracking in concrete promotes deterioration such as the corrosion of reinforcing rebar, therefore, repair in filling the crack is often carried out. Recently, repair methods using bio-based materials associated with microbial metabolic processes leading to precipitation of calcium carbonate have been intensively studied. In this study, influencing factors on the precipitation rate depending on the constituents of bio-based material comprising yeast, glucose and calcium acetate mixed in tris buffer solution was examined for improving the rate of initial reactions. In addition, effect of temperature change on the amount of calcium carbonate precipitation was also investigated. The precipitates were identified by X-ray diffraction. It was shown that the increase of temperature lead to a change on calcium carbonate precipitation and caused the pH decrease under 7.0.

  3. The influence of green microstructure and sintering parameters on precipitation process during copper-nickel-zinc ferrites sintering

    International Nuclear Information System (INIS)

    Barba, A.; Clausell, C.; Jarque, J. C.; Monzo, M.

    2014-01-01

    Microstructural changes that occur during heat treatment of copper-nickel-zinc ferrites have been studied. The process of precipitation of the two types of crystals that occur during the sintering process has been analyzed. It is found that this process depends on dry relative density of the press specimens and on the following sintering parameters: sintering temperature, sintering time and cooling rate of the thermal cycle. Crystal precipitates characterization have been done by scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) analysis, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). These techniques have allowed to determine the nature of these crystals, which in this case correspond to zinc and copper oxides. It has been used two chemical reactions to explain the bulk precipitation and subsequent re-dissolution of these crystal precipitates during sintering. (Author)

  4. 360 year temperature and precipitation record for the Pasco Basin derived from tree-ring data

    International Nuclear Information System (INIS)

    Cropper, J.P.; Fritts, H.C.

    1986-08-01

    Dendroclimatology, the study of past climatic variations by means of tree-ring analysis, is used to produce estimates of seasonal and annual temperature and precipitation from the 17th through 20th centuries. In this study these estimates, reconstructions, are derived in five different ways for regions that each include the Pasco Basin of south central Washington. The best of five sets of results were selected, based on the verification of the reconstructions with independent instrumental data. The reconstructed annual temperature of the Pasco Basin for the last three centuries was on the average 0.17 degrees Fahrenheit higher and had a standard deviation which was 4% larger than for the 20th century. The greatest reconstructed difference in the average temperature was in winter and the greatest reconstructed difference in the variance (standard deviation) was reconstructed in autumn. The average annual precipitation reconstructed for 1602 to 1900 was 0.32 inches higher than it has been in the 20th century. The change in average and standard deviation of reconstructed precipitation was greatest in autumn. Both the seasonal and annual reconstructions for temperature and precipitation exhibit large and persistent variations from the mean which are often most pronounced in the 17th century. Droughts were more common starting with the last half of the 17th century, with values that sometimes exceeded the 20th-century maximum amounts and duration. While there are some similarities among the four seasons and two variables, many differences between the seasonal reconstructions exist. 28 refs., 6 figs., 6 tabs

  5. Gridded Mean Monthly Temperature and Precipitation Data for Alaska, British Columbia, and Yukon

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — To aid in better understanding the temperature and precipitation data of the spatially variable climate of Alaska and Northwest Canada, this dataset was created via...

  6. The significance level and repeatability for isotope-temperature coefficient of precipitation in China

    International Nuclear Information System (INIS)

    Wang Dongsheng; Wang Jinglan

    2003-01-01

    The good linear relationship with significance level α = 0.01 exists between isotope in precipitation and surface air temperature with multi-year average in 32 stations of China, and the yearly δD-temperature coefficient = 3.1‰/1℃ and the yearly δ 18 O-temperature coefficient = 0.36‰/1℃, and its determination coefficient R 2 = 0.67 and 0.64 respectively. So the isotope-temperature coefficient with yearly average can serve as the temperature yearly measure. But the monthly average isotope-temperature coefficient in each station is variable according to both of space and time, and its repeatability is determined by the meteorological regimes. According to the monthly isotope-temperature coefficient (B) and the coefficient of determination (R 2 ) and its α, all of China can be zoned the following three belts: (1) In the North Belt, B>O, R 2 ≈ 0.3-0.65, α = 0.01, the relation between monthly isotope in precipitation and surface air temperature (RMIT) belongs to a direct correlation and is closer in 99% probability; (2) In the South Belt, Btemperature coefficient with both of yearly average and monthly average and its statistical attribution is site-specific, it may be used to reconstruct past surface air temperatures or to diagnose regional climate models. (authors)

  7. Precipitation Reconstructions and Periods of Drought in the Upper Green River Basin, Wyoming, USA

    Science.gov (United States)

    Follum, M.; Barnett, A.; Bellamy, J.; Gray, S.; Tootle, G.

    2008-12-01

    Due to recent drought and stress on water supplies in the Colorado River Compact States, more emphasis has been placed on the study of water resources in the Upper Green River Basin (UGRB) of Wyoming, Utah, and Colorado. The research described here focuses on the creation of long-duration precipitation records for the UGRB using tree-ring chronologies. When combined with existing proxy streamflow reconstructions and drought frequency analysis, these records offer a detailed look at hydrologic variability in the UGRB. Approximately thirty-three existing tree ring chronologies were analyzed for the UGRB area. Several new tree ring chronologies were also developed to enhance the accuracy and the geographical diversity of the resulting tree-ring reconstructions. In total, three new Douglas-fir (Pseudotsuga menziesii) and four new limber pine (Pinus flexilis) sites were added to the available tree-ring chronologies in this area. Tree-ring based reconstructions of annual (previous July through current June) precipitation were then created for each of the seventeen sub-watersheds in the UGRB. Reconstructed precipitation records extend back to at least 1654 AD, with reconstructions for some sub-basins beginning pre-1500. Variance explained (i.e. adjusted R2) ranged from 0.41 to 0.74, and the reconstructions performed well in a variety of verification tests. Additional analyses focused on stochastic estimation of drought frequency and return period, and detailed comparisons between reconstructed records and instrumental observations. Overall, this work points to the prevalence of severe, widespread drought in the UGRB. These analyses also highlight the relative wetness and lack of sustained dry periods during the instrumental period (1895-Present). Such long- term assessments are, in turn, vital tools as the Compact States contemplate the "Law of the River" in the face of climate change and ever-growing water demands.

  8. Temperature, precipitation and biotic interactions as determinants of tree seedling recruitment across the tree line ecotone.

    Science.gov (United States)

    Tingstad, Lise; Olsen, Siri Lie; Klanderud, Kari; Vandvik, Vigdis; Ohlson, Mikael

    2015-10-01

    Seedling recruitment is a critical life history stage for trees, and successful recruitment is tightly linked to both abiotic factors and biotic interactions. In order to better understand how tree species' distributions may change in response to anticipated climate change, more knowledge of the effects of complex climate and biotic interactions is needed. We conducted a seed-sowing experiment to investigate how temperature, precipitation and biotic interactions impact recruitment of Scots pine (Pinus sylvestris) and Norway spruce (Picea abies) seedlings in southern Norway. Seeds were sown into intact vegetation and experimentally created gaps. To study the combined effects of temperature and precipitation, the experiment was replicated across 12 sites, spanning a natural climate gradient from boreal to alpine and from sub-continental to oceanic. Seedling emergence and survival were assessed 12 and 16 months after sowing, respectively, and above-ground biomass and height were determined at the end of the experiment. Interestingly, very few seedlings were detected in the boreal sites, and the highest number of seedlings emerged and established in the alpine sites, indicating that low temperature did not limit seedling recruitment. Site precipitation had an overall positive effect on seedling recruitment, especially at intermediate precipitation levels. Seedling emergence, establishment and biomass were higher in gap plots compared to intact vegetation at all temperature levels. These results suggest that biotic interactions in the form of competition may be more important than temperature as a limiting factor for tree seedling recruitment in the sub- and low-alpine zone of southern Norway.

  9. A space and time scale-dependent nonlinear geostatistical approach for downscaling daily precipitation and temperature

    KAUST Repository

    Jha, Sanjeev Kumar; Mariethoz, Gregoire; Evans, Jason; McCabe, Matthew; Sharma, Ashish

    2015-01-01

    precipitation and daily temperature over several years. Here, the training image consists of daily rainfall and temperature outputs from the Weather Research and Forecasting (WRF) model at 50 km and 10 km resolution for a twenty year period ranging from 1985

  10. Observed changes in surface air temperature and precipitation in the Hindu Kush Himalayan region over the last 100-plus years

    Directory of Open Access Journals (Sweden)

    Yu-Yu Ren

    2017-09-01

    Full Text Available In this paper, we analyzed the long-term changes in temperature and precipitation in the Hindu Kush Himalayan (HKH region based on climate datasets LSAT-V1.1 and CGP1.0 recently developed by the China Meteorological Administration. The analysis results show that during 1901–2014 the annual mean surface air temperature over the whole HKH has undergone a significant increasing trend. We determined the change rates in the mean temperature, mean maximum temperature, and mean minimum temperature to be 0.104 °C per decade, 0.077 °C per decade, and 0.176 °C per decade, respectively. Most parts of the HKH have experienced a warming trend, with the largest increase occurring on the Tibetan Plateau (TP and south of Pakistan. The trend of precipitation for the whole HKH is characterized by a slight decrease during 1901–2014. During 1961–2013, however, the trend of the annual precipitation shows a statistically significant increase, with a rate of 5.28% per decade and has a more rapid increase since the mid-1980s. Most parts of northern India and the northern TP have experienced a strong increase in the number of precipitation days (daily rainfall ≥1 mm, whereas Southwest China and Myanmar have experienced a declining trend in precipitation days. Compared to the trends in precipitation days, the spatial pattern of trends in the precipitation intensity seems to be more closely related to the terrain, and the higher altitude areas have shown more significant upward trends in precipitation intensity during 1961–2013.

  11. Effect of deformation temperature on niobium clustering, precipitation and austenite recrystallisation in a Nb–Ti microalloyed steel

    International Nuclear Information System (INIS)

    Kostryzhev, Andrii G.; Al Shahrani, Abdullah; Zhu, Chen; Ringer, Simon P.; Pereloma, Elena V.

    2013-01-01

    The effect of deformation temperature on Nb solute clustering, precipitation and the kinetics of austenite recrystallisation were studied in a steel containing 0.081C–0.021Ti–0.064 Nb (wt%). Thermo-mechanical processing was carried out using a Gleeble 3500 simulator. The austenite microstructure was studied using a combination of optical microscopy, transmission electron microscopy, and atom probe microscopy, enabling a careful characterisation of grain size, as well as Nb-rich clustering and precipitation processes. A correlation between the austenite recrystallisation kinetics and the chemistry, size and number density of Nb-rich solute atom clusters, and NbTi(C,N) precipitates was established via the austenite deformation temperature. Specifically, we have determined thresholds for the onset of recrystallisation: for deformation levels above 75% and temperatures above 825 °C, Nb atom clusters <8 nm effectively suppressed austenite recrystallisation

  12. Precipitation behavior and effect of new precipitated β phase in AZ80 magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    TANG Wei; HAN En-hou; XU Yong-bo; LIU Lu

    2006-01-01

    Granular precipitate that was a new kind of β-Mg17Al12 phase found in aged AZ80 wrought Mg alloy at all aging temperature was studied. The structure and precipitation behavior of this granular β-Mg17Al12 precipitate were studied by environmental scanning electron microscopy (ESEM) and transmission electron microscopy (TEM). The effect of the granular precipitate on mechanical properties of AZ80 alloy was also studied. The new precipitate that was granular and nucleated both on grain boundaries (GBs) and twin boundaries, has the same crystal structure and lattice parameter as those of the continuous or discontinuous precipitated β-Mg17Al12. And the nucleation and growth of the granular precipitate are faster than those of the other two precipitates at higher temperatures (above 583 K), but are suppressed at lower temperatures (below 423 K). At lower temperatures, the discontinuous β-Mg17Al12 precipitates firstly and the granular β-Mg17Al12 precipitates after aged more than 40 h. The crack is easily nucleated on the phase boundaries of granular phase and matrix because of the weak binding force. As a result, the strength and ductility of AZ80 Mg alloy are decreased by the granular β-Mg17Al12 precipitate.

  13. Why are agricultural impacts of climate change so uncertain? The importance of temperature relative to precipitation

    International Nuclear Information System (INIS)

    Lobell, David B; Burke, Marshall B

    2008-01-01

    Estimates of climate change impacts are often characterized by large uncertainties that reflect ignorance of many physical, biological, and socio-economic processes, and which hamper efforts to anticipate and adapt to climate change. A key to reducing these uncertainties is improved understanding of the relative contributions of individual factors. We evaluated uncertainties for projections of climate change impacts on crop production for 94 crop-region combinations that account for the bulk of calories consumed by malnourished populations. Specifically, we focused on the relative contributions of four factors: climate model projections of future temperature and precipitation, and the sensitivities of crops to temperature and precipitation changes. Surprisingly, uncertainties related to temperature represented a greater contribution to climate change impact uncertainty than those related to precipitation for most crops and regions, and in particular the sensitivity of crop yields to temperature was a critical source of uncertainty. These findings occurred despite rainfall's important contribution to year-to-year variability in crop yields and large disagreements among global climate models over the direction of future regional rainfall changes, and reflect the large magnitude of future warming relative to historical variability. We conclude that progress in understanding crop responses to temperature and the magnitude of regional temperature changes are two of the most important needs for climate change impact assessments and adaptation efforts for agriculture

  14. Sensitivity of glaciation in the arid subtropical Andes to changes in temperature, precipitation, and solar radiation

    Science.gov (United States)

    Vargo, L. J.; Galewsky, J.; Rupper, S.; Ward, D. J.

    2018-04-01

    The subtropical Andes (18.5-27 °S) have been glaciated in the past, but are presently glacier-free. We use idealized model experiments to quantify glacier sensitivity to changes in climate in order to investigate the climatic drivers of past glaciations. We quantify the equilibrium line altitude (ELA) sensitivity (the change in ELA per change in climate) to temperature, precipitation, and shortwave radiation for three distinct climatic regions in the subtropical Andes. We find that in the western cordillera, where conditions are hyper-arid with the highest solar radiation on Earth, ELA sensitivity is as high as 34 m per % increase in precipitation, and 70 m per % decrease in shortwave radiation. This is compared with the eastern cordillera, where precipitation is the highest of the three regions, and ELA sensitivity is only 10 m per % increase in precipitation, and 25 m per % decrease in shortwave radiation. The high ELA sensitivity to shortwave radiation highlights the influence of radiation on mass balance of high elevation and low-latitude glaciers. We also consider these quantified ELA sensitivities in context of previously dated glacial deposits from the regions. Our results suggest that glaciation of the humid eastern cordillera was driven primarily by lower temperatures, while glaciations of the arid Altiplano and western cordillera were also influenced by increases in precipitation and decreases in shortwave radiation. Using paleoclimate records from the timing of glaciation, we find that glaciation of the hyper-arid western cordillera can be explained by precipitation increases of 90-160% (1.9-2.6× higher than modern), in conjunction with associated decreases in shortwave radiation of 7-12% and in temperature of 3.5 °C.

  15. Temperature Effects on the Tensile Properties of Precipitation-Hardened Al-Mg-Cu-Si Alloys

    Directory of Open Access Journals (Sweden)

    J.B. Ferguson

    2016-02-01

    Full Text Available Because the mechanical performance of precipitation-hardened alloys can be significantly altered with temperature changes, understanding and predicting the effects of temperatures on various mechanical properties for these alloys are important. In the present work, an analytical model has been developed to predict the elastic modulus, the yield stress, the failure stress, and the failure strain taking into consideration the effect of temperatures for precipitation-hardenable Al-Mg-Cu-Si Alloys (Al-A319 alloys. In addition, other important mechanical properties of Al-A319 alloys including the strain hardening exponent, the strength coefficient, and the ductility parameter can be estimated using the current model. It is demonstrated that the prediction results based on the proposed model are in good agreement with those obtained experimentally in Al-A319 alloys in the as-cast condition and after W and T7 heat treatments.

  16. Bivariate return periods of temperature and precipitation explain a large fraction of European crop yields

    Directory of Open Access Journals (Sweden)

    J. Zscheischler

    2017-07-01

    Full Text Available Crops are vital for human society. Crop yields vary with climate and it is important to understand how climate and crop yields are linked to ensure future food security. Temperature and precipitation are among the key driving factors of crop yield variability. Previous studies have investigated mostly linear relationships between temperature and precipitation and crop yield variability. Other research has highlighted the adverse impacts of climate extremes, such as drought and heat waves, on crop yields. Impacts are, however, often non-linearly related to multivariate climate conditions. Here we derive bivariate return periods of climate conditions as indicators for climate variability along different temperature–precipitation gradients. We show that in Europe, linear models based on bivariate return periods of specific climate conditions explain on average significantly more crop yield variability (42 % than models relying directly on temperature and precipitation as predictors (36 %. Our results demonstrate that most often crop yields increase along a gradient from hot and dry to cold and wet conditions, with lower yields associated with hot and dry periods. The majority of crops are most sensitive to climate conditions in summer and to maximum temperatures. The use of bivariate return periods allows the integration of non-linear impacts into climate–crop yield analysis. This offers new avenues to study the link between climate and crop yield variability and suggests that they are possibly more strongly related than what is inferred from conventional linear models.

  17. Comparative Study of the Effects of ENSO Phenomenon (El Niño, La Niña on Temperature and Precipitation of Mashhad

    Directory of Open Access Journals (Sweden)

    vajiheh mohammadi sabet

    2017-03-01

    Full Text Available Introduction: The Southern Oscillation is a large scale phenomenon that changes the Normal oscillating air pressure on both sides of the Pacific Ocean. It disrupted the normal conditions and the patterns of temperature and precipitation change in the nearby region and other regions of the world. This phenomenon is caused by changing the water slope in the Pacific Ocean between Peru (northwestern South America and Northern Australia (about Indonesia and Malaysia. ENSO phenomenon is formed of Elnino (warm state and La Niña (cold state. There is high pressure system in the East and low pressure system in the West Pacific Ocean in normal conditions (Walker cycle. The trade winds blow from East to West with high intensity. ENSO start when the trade winds and temperature and pressure balance on both sides of the PacificOcean change. High pressure will form in the west and low pressure will form in the East. As a result, west will have high and east will have low rainfall. Temperature will change at these two locations. Enso longs about 6 to 18 months. This research investigated the impact of ENSO on monthly precipitation and temperature of Mashhad.The results showed that temperature and rainfall have a good relation with ENSO.This relation occurs in 0-5 month lag. Materials and Methods: The severity of ENSO phenomenon is known by an index which is called ENSO index. The index is the anomaly of sea surface temperature in the Pacific. The long-term temperature and precipitation data of Mashhad selected and analyzed. The Rainfall has no trend but temperature has trend. The trend of temperature modeled by MARS regression and trend was removed.The rainfall data changed to standard and temperature changed to anomaly for comparison with ENSO index. The 2016 annual and monthly temperature of Mashhad is not available. The 2016 Annual temperature was forecasted by ARMA (1,1 model. Then this forecast disaggregated to monthly temperature. For each period of

  18. The temperature dependent strontium isotope fractionation (δ88/86Sr) during calcium carbonate precipitation

    International Nuclear Information System (INIS)

    Fietzke, J.; Eisenhauer, A.

    2006-01-01

    Full text: In order to study the influence of stable isotope fractionation during inorganic and biologically controlled CaCO 3 precipitation we have developed the analytical principles for the measurement of strontium (Sr) isotope fractionation. We have established a measurement protocol for the application on a MC-ICP-MS (AXIOM) using the common bracketing standard technique. The Sr-standard CRM NBS987 was used as reference material for all measurements and to calculate the Sr fractionation. Latter value is expressed by the δ-notation defined as: δ 88/86 Sr = [( 88 Sr/ 86 Sr)sample / ( 88 Sr/ 86 Sr)standard ] * 1000 -1. A first set of experiments focused on the temperature dependency of Sr-isotope fractionation. For this purpose inorganically precipitated aragonite and calcite was prepared under controlled conditions in a temperature range from 10 to 50 o C. In addition, cultured and naturally grown corals were analyzed for their δ 88/86 Sr values. Repeated measurements of IAPSO seawater standard showed a mean δ 88/86 Sr value of 0.383 ± 0.008 (2 SEM) being the isotopically heaviest material measured so far. The first results of the inorganically precipitated aragonite and the natural corals revealed a clear temperature dependency of the δ 88/86 Sr values. For inorganic aragonite the slope of this correlation is about 0.0055 permil/ o C. However, for naturally grown corals (Pavona clavus) a 6 fold steeper slope of 0.033 permil/ o C was determined. This strong temperature dependency implies the potential to use stable Sr isotopes as a new marine (paleo)temperature proxy. (author)

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

    Science.gov (United States)

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

    2018-04-01

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

  20. A DLTS study of the evolution of oxygen precipitates in Si at high temperature and high pressure

    International Nuclear Information System (INIS)

    Antonova, I.V.; Popov, V.P.; Fedina, L.I.; Shaimeev, S.S.; Misiuk, A.

    1996-01-01

    The effect of high hydrostatic pressure on the dissolution of oxygen precipitates introduced beforehand into Si at temperatures of 920-1000 K (over period of 96 h) is investigated by the DLTS method. A measurement procedure, based on the formation of electrically active complexes (interstitial oxygen atom-vacancy) during electron irradiation of the samples, is proposed. It is shown that the precipitates do not decompose when point defects are introduced at room temperature. As the treatment temperature increases (to 1220-1650 K), for the same values of the hydrostatic pressure (up to 1.3 GPa) the intensity of the decomposition of oxygen precipitates increases and at 1650 K they are completely dissolved. Study of the decomposition kinetics showed that hydrostatic pressure raises the limit of solubility of the oxygen atoms Oi and slows down their diffusion. It is determined that the diffusion activation energy Ea, just as the preexponential factor D0, in the expression for the diffusion decrease with increasing hydrostatic pressure, resulting in a lower diffusion. Possible mechanisms for the effect of hydrostatic pressure on oxygen diffusion near a precipitate are discussed

  1. Discontinuities of Green functions in field theory at finite temperature and density

    International Nuclear Information System (INIS)

    Kobes, R.L.; Semenoff, G.W.

    1985-01-01

    We derive systematic rules for calculating the imaginary parts of Minkowski space Green functions in quantum field theory at finite temperature and density. Self-energy corrections are used as an example of the application of these rules. (orig.)

  2. The Effect of Urban Green Infrastructure on Disaster Mitigation in Korea

    Directory of Open Access Journals (Sweden)

    So Yoon Kim

    2017-06-01

    Full Text Available Increasing precipitation by climate change and the growing number of impervious areas present greater risk of disaster damage in urban areas. Urban green infrastructure can be an effective mitigation alternative in highly developed and concentrated area. This study investigates the effect of various types of urban green infrastructure on mitigating disaster damage in Korea. Tobit model is used to analyze the factors that determine disaster damage. Damage variation is predicted with scenarios of RCP 8.5 and urban green spaces. Seventy-four districts and counties in seven metropolitan areas are defined as the unit and the period from 2005 to 2013 is considered in the analysis. The results indicate that higher urban green ratio, sewer length, financial independence rate, and local government’s budget are relating to lower disaster damage. Based on a precipitation level of RCP 8.5 scenario in 2050, an increase in economic damage is expected to range from 262 to 1086%. However, with an increase in urban green ratio by 10%, increased economic damage is only expected to range from 217 to 1013%. The results suggest that green spaces play important role to mitigate precipitation related disasters. Highly concentrated urban areas need to consider various types of urban green infrastructure to prepare for an increase in precipitation due to climate change.

  3. Indirect downscaling of global circulation model data based on atmospheric circulation and temperature for projections of future precipitation in hourly resolution

    Science.gov (United States)

    Beck, F.; Bárdossy, A.

    2013-07-01

    Many hydraulic applications like the design of urban sewage systems require projections of future precipitation in high temporal resolution. We developed a method to predict the regional distribution of hourly precipitation sums based on daily mean sea level pressure and temperature data from a Global Circulation Model. It is an indirect downscaling method avoiding uncertain precipitation data from the model. It is based on a fuzzy-logic classification of atmospheric circulation patterns (CPs) that is further subdivided by means of the average daily temperature. The observed empirical distributions at 30 rain gauges to each CP-temperature class are assumed as constant and used for projections of the hourly precipitation sums in the future. The method was applied to the CP-temperature sequence derived from the 20th century run and the scenario A1B run of ECHAM5. According to ECHAM5, the summers in southwest Germany will become progressively drier. Nevertheless, the frequency of the highest hourly precipitation sums will increase. According to the predictions, estival water stress and the risk of extreme hourly precipitation will both increase simultaneously during the next decades.

  4. Correlation and SVD Analysis of Anomalous Spring Precipitation in Northwest China and Sea Surface Temperature in Key Region in Recent 50 Years

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    [Objective] The aim was to study the relationship between spring precipitation anomaly in Northwest China and sea surface temperature anomaly (SSTA) in Key region in recent 50 years. [Method] Based on monthly average precipitation in Northwest China and global monthly sea surface temperature (SST) grid data, the effects of SSTA in equatorial central and eastern Pacific on spring precipitation in Northwest China were discussed by means of correlation and SVD analysis. [Result] For spring precipitation in Nor...

  5. The long-term trends (1982-2006) in vegetation greenness of the alpine ecosystem in the Qinghai-Tibetan Plateau

    Science.gov (United States)

    Zhang, Li; Guo, Huadong; Wang, Cuizhen; Ji, Lei; Li, Jing; Wang, Kun; Dai, Lin

    2014-01-01

    The increased rate of annual temperature in the Qinghai-Tibetan Plateau exceeded all other areas of the same latitude in recent decades. The influence of the warming climate on the alpine ecosystem of the plateau was distinct. An analysis of alpine vegetation under changes in climatic conditions was conducted in this study. This was done through an examination of vegetation greenness and its relationship with climate variability using the Advanced Very High Resolution Radiometer satellite imagery and climate datasets. Vegetation in the plateau experienced a positive trend in greenness, with 18.0 % of the vegetated areas exhibiting significantly positive trends, which were primarily located in the eastern and southwestern parts of the plateau. In grasslands, 25.8 % of meadows and 14.1 % of steppes exhibited significant upward trends. In contrast, the broadleaf forests experienced a trend of degradation. Temperature, particularly summer temperature, was the primary factor promoting the vegetation growth in the plateau. The wetter and warmer climate in the east contributed to the favorable conditions for vegetation. The alpine meadow was mostly sensitive to temperature, while the steppes were sensitive to both temperature and precipitation. Although a warming climate was expected to be beneficial to vegetation growth in the alpine region, the rising temperature coupled with reduced precipitation in the south did not favor vegetation growth due to low humidity and poor soil moisture conditions.

  6. Temperature-dependent striped antiferromagnetism of LaFeAsO in a Green's function approach

    International Nuclear Information System (INIS)

    Liu Guibin; Liu Banggui

    2009-01-01

    We use a Green's function method to study the temperature-dependent average moment and magnetic phase-transition temperature of the striped antiferromagnetism of LaFeAsO, and other similar compounds, as the parents of FeAs-based superconductors. We consider the nearest and the next-nearest couplings in the FeAs layer, and the nearest coupling for inter-layer spin interaction. The dependence of the transition temperature T N and the zero-temperature average spin on the interaction constants is investigated. We obtain an analytical expression for T N and determine our temperature-dependent average spin from zero temperature to T N in terms of unified self-consistent equations. For LaFeAsO, we obtain a reasonable estimation of the coupling interactions with the experimental transition temperature T N = 138 K. Our results also show that a non-zero antiferromagnetic (AFM) inter-layer coupling is essential for the existence of a non-zero T N , and the many-body AFM fluctuations reduce substantially the low-temperature magnetic moment per Fe towards the experimental value. Our Green's function approach can be used for other FeAs-based parent compounds and these results should be useful to understand the physical properties of FeAs-based superconductors.

  7. Record dry summer in 2015 challenges precipitation projections in Central Europe

    Science.gov (United States)

    Orth, René; Zscheischler, Jakob; Seneviratne, Sonia I.

    2016-06-01

    Central Europe was characterized by a humid-temperate climate in the 20th century. Climate change projections suggest that climate in this area will shift towards warmer temperatures by the end of the 21st century, while projected precipitation changes are highly uncertain. Here we show that the 2015 summer rainfall was the lowest on record since 1901 in Central Europe, and that climate models that perform best in the three driest years of the historical time period 1901-2015 project stronger drying trends in the 21st century than models that perform best in the remaining years. Analyses of precipitation and derived soil moisture reveal that the 2015 event was drier than both the recent 2003 or 2010 extreme summers in Central Europe. Additionally there are large anomalies in satellite-derived vegetation greenness. In terms of precipitation and temperature anomalies, the 2015 summer in Central Europe is found to lie between historical climate in the region and that characteristic of the Mediterranean area. Even though the models best capturing past droughts are not necessarily generally more reliable in the future, the 2015 drought event illustrates that potential future drying trends have severe implications and could be stronger than commonly assumed from the entire IPCC AR5 model ensemble.

  8. Global land carbon sink response to temperature and precipitation varies with ENSO phase

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Yuanyuan; Michalak, Anna M.; Schwalm, Christopher R.; Huntzinger, Deborah N.; Berry, Joseph A.; Ciais, Philippe; Piao, Shilong; Poulter, Benjamin; Fisher, Joshua B.; Cook, Robert B.; Hayes, Daniel; Huang, Maoyi; Ito, Akihiko; Jain, Atul; Lei, Huimin; Lu, Chaoqun; Mao, Jiafu; Parazoo, Nicholas C.; Peng, Shushi; Ricciuto, Daniel M.; Shi, Xiaoying; Tao, Bo; Tian, Hanqin; Wang, Weile; Wei, Yaxing; Yang, Jia

    2017-05-01

    Climate variability associated with the El Niño-Southern Oscillation (ENSO) and its consequent impacts on land carbon sink interannual variability have been used as a basis for investigating carbon cycle responses to climate variability more broadly, and to inform the sensitivity of the tropical carbon budget to climate change. Past studies have presented opposing views about whether temperature or precipitation is the primary factor driving the response of the land carbon sink to ENSO. Here, we show that the dominant driver varies with ENSO phase. Whereas tropical temperature explains sink dynamics following El Niño conditions (rTG,P=0.59, p<0.01), the post La Niña sink is driven largely by tropical precipitation (rPG,T=-0.46, p=0.04). This finding points to an ENSO-phase-dependent interplay between water availability and temperature in controlling the carbon uptake response to climate variations in tropical ecosystems. We further find that none of a suite of ten contemporary terrestrial biosphere models captures these ENSO-phase-dependent responses, highlighting a key uncertainty in modeling climate impacts on the future of the global land carbon sink.

  9. The influence of the circulation on surface temperature and precipitation patterns over Europe

    Directory of Open Access Journals (Sweden)

    P. D. Jones

    2009-06-01

    Full Text Available The atmospheric circulation clearly has an important influence on variations in surface temperature and precipitation. In this study we illustrate the spatial patterns of variation that occur for the principal circulation patterns across Europe in the standard four seasons. We use an existing classification scheme of surface pressure patterns, with the aim of considering whether the patterns of influence of specific weather types have changed over the course of the 20th century. We consider whether the long-term warming across Europe is associated with more favourable weather types or related to warming within some of the weather types. The results indicate that the latter is occurring, but not all circulation types show warming. The study also illustrates that certain circulation types can lead to marked differences in temperature and/or precipitation for relatively closely positioned sites when the sites are located in areas of high relief or near coasts.

  10. Impacts of climate change on the microbial safety of pre-harvest leafy green vegetables as indicated by Escherichia coli O157 and Salmonella spp.

    NARCIS (Netherlands)

    Liu, C.; Hofstra, N.; Franz, E.

    2013-01-01

    The likelihood of leafy green vegetable (LGV) contamination and the associated pathogen growth and survival are strongly related to climatic conditions. Particularly temperature increase and precipitation pattern changes have a close relationship not only with the fate and transport of enteric

  11. Reproducibility of summertime diurnal precipitation over northern Eurasia simulated by CMIP5 climate models

    Science.gov (United States)

    Hirota, N.; Takayabu, Y. N.

    2015-12-01

    Reproducibility of diurnal precipitation over northern Eurasia simulated by CMIP5 climate models in their historical runs were evaluated, in comparison with station data (NCDC-9813) and satellite data (GSMaP-V5). We first calculated diurnal cycles by averaging precipitation at each local solar time (LST) in June-July-August during 1981-2000 over the continent of northern Eurasia (0-180E, 45-90N). Then we examined occurrence time of maximum precipitation and a contribution of diurnally varying precipitation to the total precipitation.The contribution of diurnal precipitation was about 21% in both NCDC-9813 and GSMaP-V5. The maximum precipitation occurred at 18LST in NCDC-9813 but 16LST in GSMaP-V5, indicating some uncertainties even in the observational datasets. The diurnal contribution of the CMIP5 models varied largely from 11% to 62%, and their timing of the precipitation maximum ranged from 11LST to 20LST. Interestingly, the contribution and the timing had strong negative correlation of -0.65. The models with larger diurnal precipitation showed precipitation maximum earlier around noon. Next, we compared sensitivity of precipitation to surface temperature and tropospheric humidity between 5 models with large diurnal precipitation (LDMs) and 5 models with small diurnal precipitation (SDMs). Precipitation in LDMs showed high sensitivity to surface temperature, indicating its close relationship with local instability. On the other hand, synoptic disturbances were more active in SDMs with a dominant role of the large scale condensation, and precipitation in SDMs was more related with tropospheric moisture. Therefore, the relative importance of the local instability and the synoptic disturbances was suggested to be an important factor in determining the contribution and timing of the diurnal precipitation. Acknowledgment: This study is supported by Green Network of Excellence (GRENE) Program by the Ministry of Education, Culture, Sports, Science and Technology

  12. Spatiotemporal extremes of temperature and precipitation during 1960-2015 in the Yangtze River Basin (China) and impacts on vegetation dynamics

    Science.gov (United States)

    Cui, Lifang; Wang, Lunche; Qu, Sai; Singh, Ramesh P.; Lai, Zhongping; Yao, Rui

    2018-05-01

    Recently, extreme climate variation has been studied in different parts of the world, and the present study aims to study the impacts of climate extremes on vegetation. In this study, we analyzed the spatiotemporal variations of temperature and precipitation extremes during 1960-2015 in the Yangtze River Basin (YRB) using the Mann-Kendall (MK) test with Sen's slope estimator and kriging interpolation method based on daily precipitation (P), maximum temperature (T max), and minimum temperature (T min). We also analyzed the vegetation dynamics in the YRB during 1982-2015 using Global Inventory Modeling and Mapping Studies (GIMMS) normalized difference vegetation index (NDVI) datasets and investigated the relationship between temperature and precipitation extremes and NDVI using Pearson correlation coefficients. The results showed a pronounced increase in the annual mean maximum temperature (T nav) and mean minimum temperature (T xav) at the rate of 0.23 °C/10 years and 0.15 °C/10 years, respectively, during 1960-2015. In addition, the occurrence of warm days and warm nights shows increasing trends at the rate of 1.36 days/10 years and 1.70 days/10 years, respectively, while cold days and cold nights decreased at the rate of 1.09 days/10 years and 2.69 days/10 years, respectively, during 1960-2015. The precipitation extremes, such as very wet days (R95, the 95th percentile of daily precipitation events), very wet day precipitation (R95p, the number of days with rainfall above R95), rainstorm (R50, the number of days with rainfall above 50 mm), and maximum 1-day precipitation (RX1day), all show pronounced increasing trends during 1960-2015. In general, annual mean NDVI over the whole YRB increased at the rate of 0.01/10 years during 1982-2015, with an increasing transition around 1994. Spatially, annual mean NDVI increased in the northern, eastern, and parts of southwestern YRB, while it decreased in the YRD and parts of southern YRB during 1982-2015. The correlation

  13. Kinetics of ikaite precipitation and dissolution in seawater-derived brines at sub-zero temperatures to 265 K

    Science.gov (United States)

    Papadimitriou, Stathys; Kennedy, Hilary; Kennedy, Paul; Thomas, David N.

    2014-09-01

    The kinetics of calcium carbonate hexahydrate (ikaite) precipitation and dissolution were investigated in seawater and seawater-derived brines at sub-zero temperatures using the constant addition experimental technique. The steady state rate of these two processes was found to be a function of the deviation of the solution from equilibrium with respect to ikaite and conformed to the same empirical rate law as the anhydrous CaCO3 polymorphs, calcite and aragonite. In addition to the saturation state of the brine with respect to ikaite, the salinity of the brine and the temperature of the reaction evidently exerted some control on the ikaite precipitation kinetics, while the dissolution kinetics of the polymorph were not noticeably influenced by these two parameters. The experimental salinity and temperature conditions were equivalent to those at thermal equilibrium between brine and ice in the sea ice cover of polar seas. Simple modelling of the CO2 system by extrapolation of the oceanic equivalent to sea ice brines showed that the physical concentration of seawater ions and the changes in ikaite solubility as a function of salinity and temperature, both inherent in the sea ice system, would be insufficient to drive the emergent brines to ikaite supersaturation and precipitation in sea ice down to -8 °C. The loss of dissolved inorganic carbon to the gas phase of sea ice and to sympagic autotrophs are two independent mechanisms which, in nature, could prompt the brine CO2 system towards ikaite supersaturation and precipitation. Under these conditions, the steady state precipitation rate of ikaite was found to be fast enough for rapid formation within short time scales (days to weeks) in sea ice. The observed ikaite dissolution kinetics were also found conducive to short turn-over time scales of a few hours to a few days in corrosive solutions, such as surface seawater.

  14. Homogenization of long instrumental temperature and precipitation series over the Spanish Northern Coast

    Science.gov (United States)

    Sigro, J.; Brunet, M.; Aguilar, E.; Stoll, H.; Jimenez, M.

    2009-04-01

    The Spanish-funded research project Rapid Climate Changes in the Iberian Peninsula (IP) Based on Proxy Calibration, Long Term Instrumental Series and High Resolution Analyses of Terrestrial and Marine Records (CALIBRE: ref. CGL2006-13327-C04/CLI) has as main objective to analyse climate dynamics during periods of rapid climate change by means of developing high-resolution paleoclimate proxy records from marine and terrestrial (lakes and caves) deposits over the IP and calibrating them with long-term and high-quality instrumental climate time series. Under CALIBRE, the coordinated project Developing and Enhancing a Climate Instrumental Dataset for Calibrating Climate Proxy Data and Analysing Low-Frequency Climate Variability over the Iberian Peninsula (CLICAL: CGL2006-13327-C04-03/CLI) is devoted to the development of homogenised climate records and sub-regional time series which can be confidently used in the calibration of the lacustrine, marine and speleothem time series generated under CALIBRE. Here we present the procedures followed in order to homogenise a dataset of maximum and minimum temperature and precipitation data on a monthly basis over the Spanish northern coast. The dataset is composed of thirty (twenty) precipitation (temperature) long monthly records. The data are quality controlled following the procedures recommended by Aguilar et al. (2003) and tested for homogeneity and adjusted by following the approach adopted by Brunet et al. (2008). Sub-regional time series of precipitation, maximum and minimum temperatures for the period 1853-2007 have been generated by averaging monthly anomalies and then adding back the base-period mean, according to the method of Jones and Hulme (1996). Also, a method to adjust the variance bias present in regional time series associated over time with varying sample size has been applied (Osborn et al., 1997). The results of this homogenisation exercise and the development of the associated sub-regional time series

  15. Influence of temperature and hydrogen content on stress-induced radial hydride precipitation in Zircaloy-4 cladding

    Energy Technology Data Exchange (ETDEWEB)

    Desquines, J., E-mail: jean.desquines@irsn.fr; Drouan, D.; Billone, M.; Puls, M.P.; March, P.; Fourgeaud, S.; Getrey, C.; Elbaz, V.; Philippe, M.

    2014-10-15

    Radial hydride precipitation in stress relieved Zircaloy-4 fuel claddings is studied using a new thermal–mechanical test. Two maximum temperatures for radial hydride precipitation heat treatment are studied, 350 and 450 °C with hydrogen contents ranging between 50 and 600 wppm. The new test provides two main results of interest: the minimum hoop stress required to precipitate radial hydrides and a maximum stress above which, all hydrides precipitate in the radial direction. Based on these two extreme stress conditions, a model is derived to determine the stress level required to obtain a given fraction of radial hydrides after high temperature thermal–mechanical heat treatment. The proposed model is validated using metallographic observation data on pressurized tubes cooled down under constant pressure. Most of the samples with reoriented hydrides are further subjected to a ductility test. Using finite element modeling, the test results are analyzed in terms of crack nucleation within radial hydrides at the outer diameter and crack growth through the thickness of the tubular samples. The combination of test results shows that samples with hydrogen contents of about 100 wppm had the lowest ductility.

  16. Influence of land-atmosphere feedbacks on temperature and precipitation extremes in the GLACE-CMIP5 ensemble

    Science.gov (United States)

    Lorenz, Ruth; Argueso, Daniel; Donat, Markus G.; Pitman, Andrew J.; van den Hurk, Bart; Berg, Alexis; Lawrence, David M.; Cheruy, Frederique; Ducharne, Agnes; Hagemann, Stefan; Meier, Arndt; Milly, Paul C.D.; Seneviratne, Sonia I

    2016-01-01

    We examine how soil moisture variability and trends affect the simulation of temperature and precipitation extremes in six global climate models using the experimental protocol of the Global Land-Atmosphere Coupling Experiment of the Coupled Model Intercomparison Project, Phase 5 (GLACE-CMIP5). This protocol enables separate examinations of the influences of soil moisture variability and trends on the intensity, frequency, and duration of climate extremes by the end of the 21st century under a business-as-usual (Representative Concentration Pathway 8.5) emission scenario. Removing soil moisture variability significantly reduces temperature extremes over most continental surfaces, while wet precipitation extremes are enhanced in the tropics. Projected drying trends in soil moisture lead to increases in intensity, frequency, and duration of temperature extremes by the end of the 21st century. Wet precipitation extremes are decreased in the tropics with soil moisture trends in the simulations, while dry extremes are enhanced in some regions, in particular the Mediterranean and Australia. However, the ensemble results mask considerable differences in the soil moisture trends simulated by the six climate models. We find that the large differences between the models in soil moisture trends, which are related to an unknown combination of differences in atmospheric forcing (precipitation, net radiation), flux partitioning at the land surface, and how soil moisture is parameterized, imply considerable uncertainty in future changes in climate extremes.

  17. Effects of the aging temperature and stress relaxation conditions on γ′ precipitation in Inconel X-750

    Energy Technology Data Exchange (ETDEWEB)

    Ha, Jeong Won [Department of Materials Science and Engineering, Pusan National University, Busan 609-735 (Korea, Republic of); Research and Development Center, KOS Limited, Yangsan 626-230 (Korea, Republic of); Seong, Baek Seok [Neutron Science Division, HANARO Center, Korea Atomic Energy Research Institute, Daejeon 305-353 (Korea, Republic of); Jeong, Hi Won [Advanced Metallic Materials Division, Korea Institute of Materials Science, Changwon 642-831 (Korea, Republic of); Choi, Yoon Suk [Department of Materials Science and Engineering, Pusan National University, Busan 609-735 (Korea, Republic of); Kang, Namhyun, E-mail: nhkang@pusan.ac.kr [Department of Materials Science and Engineering, Pusan National University, Busan 609-735 (Korea, Republic of)

    2015-02-15

    Highlights: • Stress relaxation after aging 620 °C increased carbides and maintained γ′ fraction. • Aging temperature increase to 732 °C raised the γ′ increment after stress relaxation. • Small increase of carbides induced the large increase of γ′ after stress relaxation. • Loading for stress relaxation raised γ′ increment due to dislocation multiplication. - Abstract: Inconel X-750 is a Ni-based precipitation-hardened superalloy typically used in springs designed for high-temperature applications such as the hold-down springs in nuclear power plants. γ′ is a major precipitate in X-750 alloys which affects the strength, creep resistance, and stress relaxation properties of the spring. In this study, a solution-treated X-750 wire coiled into a spring was used that was aged at various temperatures and submitted to stress relaxation tests with and without loading. Small angle neutron scattering was employed to quantify the size and volume fraction of γ′ phase in the springs as a function of the aging temperature and the application of a load during stress relaxation. The volume fraction of γ′ precipitates increased in the specimen aged at 732 °C following stress relaxation at 500 °C for 300 h. However, the mean size of the precipitates in the samples was not affected by stress relaxation. The specimen aged at the lower temperature (620 °C) contained a smaller γ′ volume fraction and gained a smaller fraction of γ′ during stress relaxation compared with the sample aged at the higher temperature (732 °C). The smaller increase in the γ′ volume fraction for the sample aged at 620 °C was associated with a larger increase in the M{sub 23}C{sub 6} secondary carbide content during relaxation. The Cr depletion zone around the secondary carbides raises the solubility of γ′ thereby decreasing the volume fraction of γ′ precipitates in Inconel X-750. In terms of stress relaxation, a larger increase in the γ′ volume fraction was

  18. Atmospheric pollen season in Zagreb (Croatia) and its relationship with temperature and precipitation

    Science.gov (United States)

    Peternel, Renata; Srnec, Lidija; Čulig, Josip; Zaninović, Ksenija; Mitić, Božena; Vukušić, Ivan

    . The number of individuals allergic to plant pollen has recently been on a constant increase, especially in large cities and industrial areas. Therefore, monitoring of airborne pollen types and concentrations during the pollen season is of the utmost medical importance. The research reported in this paper aims to determine the beginning, course and end of the pollen season for the plants in the City of Zagreb, to identify allergenic plants, and to assess the variation in airborne pollen concentration as a function of temperature and precipitation changes for the year 2002. A volumetric Hirst sampler was used for airborne pollen sampling. Qualitative and quantitative pollen analysis was performed under a light microscope (magnification ×400). In the Zagreb area, 12 groups of highly allergenic plants (alder, hazel, cypress, birch, ash, hornbeam, grasses, elder, nettles, sweet chestnut, artemisia and ambrosia) were identified. Birch pollen predominated in spring, the highest concentrations being recorded in February and March. Grass pollen prevailed in May and June, and pollen of herbaceous plants of the genus Urtica (nettle) and of ambrosia in July, August and September. Air temperature was mostly higher or considerably higher than the annual average in those months, which resulted in a many days with high and very high airborne pollen concentrations. The exception was April, when these concentrations were lower because of high levels of precipitation. This also held for the first half of August and the second half of September. Pollen-sensitive individuals were at high risk from February till October because of the high airborne pollen concentrations, which only showed a transient decrease when the temperature fell or there was precipitation.

  19. A statistical method to get surface level air-temperature from satellite observations of precipitable water

    Digital Repository Service at National Institute of Oceanography (India)

    Pankajakshan, T.; Shikauchi, A; Sugimori, Y.; Kubota, M.

    -T a and precipitable water. The rms errors of the SSMI-T a , in this case are found to be reduced to 1.0°C. 1. Introduction Satellite derived surface-level meteorological parameters are considered to be a better alternative to sparse ship... Vol. 49, pp. 551 to 558. 1993 A Statistical Method to Get Surface Level Air-Temperature from Satellite Observations of Precipitable Water PANKAJAKSHAN THADATHIL*, AKIRA SHIKAUCHI, YASUHIRO SUGIMORI and MASAHISA KUBOTA School of Marine Science...

  20. Linking climate change and health outcomes: Examining the relationship between temperature, precipitation and birth weight in Africa

    Science.gov (United States)

    Grace, Kathryn; Davenport, Frank; Hanson, Heidi; Funk, Christopher C.; Shukla, Shraddhanand

    2015-01-01

    This paper examined the relationship between birth weight, precipitation, and temperature in 19 African countries. We matched recorded birth weights from Demographic and Health Surveys covering 1986 through 2010 with gridded monthly precipitation and temperature data derived from satellite and ground-based weather stations. Observed weather patterns during various stages of pregnancy were also used to examine the effect of temperature and precipitation on birth weight outcomes. In our empirical model we allowed the effect of weather factors to vary by the dominant food production strategy (livelihood zone) in a given region as well as by household wealth, mother's education and birth season. This allowed us to determine if certain populations are more or less vulnerable to unexpected weather changes after adjusting for known covariates. Finally we measured effect size by observing differences in birth weight outcomes in women who have one low birth weight experience and at least one healthy birth weight baby. The results indicated that climate does indeed impact birth weight and at a level comparable, in some cases, to the impact of increasing women's education or household electricity status.

  1. Biochar increases plant growth and alters microbial communities via regulating the moisture and temperature of green roof substrates.

    Science.gov (United States)

    Chen, Haoming; Ma, Jinyi; Wei, Jiaxing; Gong, Xin; Yu, Xichen; Guo, Hui; Zhao, Yanwen

    2018-09-01

    Green roofs have increasingly been designed and applied to relieve environmental problems, such as water loss, air pollution as well as heat island effect. Substrate and vegetation are important components of green roofs providing ecosystem services and benefiting the urban development. Biochar made from sewage sludge could be potentially used as the substrate amendment for green roofs, however, the effects of biochar on substrate quality and plant performance in green roofs are still unclear. We evaluated the effects of adding sludge biochar (0, 5, 10, 15 and 20%, v/v) to natural soil planted with three types of plant species (ryegrass, Sedum lineare and cucumber) on soil properties, plant growth and microbial communities in both green roof and ground ecosystems. Our results showed that sludge biochar addition significantly increased substrate moisture, adjusted substrate temperature, altered microbial community structure and increased plant growth. The application rate of 10-15% sludge biochar on the green roof exerted the most significant effects on both microbial and plant biomass by 63.9-89.6% and 54.0-54.2% respectively. Path analysis showed that biochar addition had a strong effect on microbial biomass via changing the soil air-filled porosity, soil moisture and temperature, and promoted plant growth through the positive effects on microbial biomass. These results suggest that the applications of biochar at an appropriate rate can significantly alter plant growth and microbial community structure, and increase the ecological benefits of green roofs via exerting effects on the moisture, temperature and nutrients of roof substrates. Copyright © 2018 Elsevier B.V. All rights reserved.

  2. Empirically Derived and Simulated Sensitivity of Vegetation to Climate Across Global Gradients of Temperature and Precipitation

    Science.gov (United States)

    Quetin, G. R.; Swann, A. L. S.

    2017-12-01

    Successfully predicting the state of vegetation in a novel environment is dependent on our process level understanding of the ecosystem and its interactions with the environment. We derive a global empirical map of the sensitivity of vegetation to climate using the response of satellite-observed greenness and leaf area to interannual variations in temperature and precipitation. Our analysis provides observations of ecosystem functioning; the vegetation interactions with the physical environment, across a wide range of climates and provide a functional constraint for hypotheses engendered in process-based models. We infer mechanisms constraining ecosystem functioning by contrasting how the observed and simulated sensitivity of vegetation to climate varies across climate space. Our analysis yields empirical evidence for multiple physical and biological mediators of the sensitivity of vegetation to climate as a systematic change across climate space. Our comparison of remote sensing-based vegetation sensitivity with modeled estimates provides evidence for which physiological mechanisms - photosynthetic efficiency, respiration, water supply, atmospheric water demand, and sunlight availability - dominate the ecosystem functioning in places with different climates. Earth system models are generally successful in reproducing the broad sign and shape of ecosystem functioning across climate space. However, this general agreement breaks down in hot wet climates where models simulate less leaf area during a warmer year, while observations show a mixed response but overall more leaf area during warmer years. In addition, simulated ecosystem interaction with temperature is generally larger and changes more rapidly across a gradient of temperature than is observed. We hypothesize that the amplified interaction and change are both due to a lack of adaptation and acclimation in simulations. This discrepancy with observations suggests that simulated responses of vegetation to

  3. High-temperature electronic structure with the Korringa-Kohn-Rostoker Green's function method

    Science.gov (United States)

    Starrett, C. E.

    2018-05-01

    Modeling high-temperature (tens or hundreds of eV), dense plasmas is challenging due to the multitude of non-negligible physical effects including significant partial ionization and multisite effects. These effects cause the breakdown or intractability of common methods and approximations used at low temperatures, such as pseudopotentials or plane-wave basis sets. Here we explore the Korringa-Kohn-Rostoker Green's function method at these high-temperature conditions. The method is all electron, does not rely on pseudopotentials, and uses a spherical harmonic basis set, and so avoids the aforementioned limitations. It is found to be accurate for solid density aluminum and iron plasmas when compared to a plane-wave method at low temperature, while being able to access high temperatures.

  4. Sensitive Indicators of Zonal Stipa Species to Changing Temperature and Precipitation in Inner Mongolia Grassland, China

    Science.gov (United States)

    Lv, Xiaomin; Zhou, Guangsheng; Wang, Yuhui; Song, Xiliang

    2016-01-01

    Climate change often induces shifts in plant functional traits. However, knowledge related to sensitivity of different functional traits and sensitive indicator representing plant growth under hydrothermal change remains unclear. Inner Mongolia grassland is predicted to be one of the terrestrial ecosystems which are most vulnerable to climate change. In this study, we analyzed the response of four zonal Stipa species (S. baicalensis, S. grandis, S. breviflora, and S. bungeana) from Inner Mongolia grassland to changing temperature (control, increased 1.5, 2, 4, and 6°C), precipitation (decreased 30 and 15%, control, increased 15 and 30%) and their combined effects via climate control chambers. The relative change of functional traits in the unit of temperature and precipitation change was regarded as sensitivity coefficient and sensitive indicators were examined by pathway analysis. We found that sensitivity of the four Stipa species to changing temperature and precipitation could be ranked as follows: S. bungeana > S. grandis > S. breviflora > S. baicalensis. In particular, changes in leaf area, specific leaf area and root/shoot ratio could account for 86% of the changes in plant biomass in the four Stipa species. Also these three measurements were more sensitive to hydrothermal changes than the other functional traits. These three functional indicators reflected the combination of plant production capacity (leaf area), adaptive strategy (root/shoot ratio), instantaneous environmental effects (specific leaf area), and cumulative environmental effects (leaf area and root/shoot ratio). Thus, leaf area, specific leaf area and root/shoot ratio were chosen as sensitive indicators in response to changing temperature and precipitation for Stipa species. These results could provide the basis for predicting the influence of climate change on Inner Mongolia grassland based on the magnitude of changes in sensitive indicators. PMID:26904048

  5. [Capacity of extensive green roof to retain rainwater runoff in hot and humid region.

    Science.gov (United States)

    Liu, Ming Xin; Dai, Se Ping; Zhou, Tian Yang; Ruan, Lin; Zhang, Qiao Song

    2017-02-01

    The water logging has become the environmental problem of major cities with the sharp increase of impermeable urban pavement as the contributing cause. Abroad, the green roof has been widely used as a practical measure to intercept rainwater, yet the capacity of green roof to retain rainwater varies with climate conditions. As the hot and humid climate zone features high temperature, humidity and precipitation, it is meaningful to study the capacity of green roof to retain rainwater under such climatic condition. In this research, 3 plat forms were set up in Guangzhou in rainy and hot summer to test the capability of simple green roof to retain rainwater runoff, and the efficiency of green roof to retain rainwater under local climate conditions was worked out based on the meteorological observation and data measurement during the 13-month test period. The results showed that the simple green roof with a substrate thickness of 30, 50 and 70 mm could retain 27.2%, 30.9% and 32.1% of precipitation and reduce the average peak value by 18.9%, 26.2% and 27.7%, respectively. Given an urban built-up area of 1035.01 km 2 in Guangzhou and a roof area percentage of approximately 37.3% and assuming the green roofs with 30 mm-thick substrate were applied within the area, the light, medium and heavy rain could be delayed at 72.8%, 22.6% and 17.4%, respectively. Accordingly, the rainwater retained could reach up to 14317×10 4 m 3 . It suggested the great potential of the simple green roof in retaining rainwater. The research could serve as reference for the hot and humid climate zone to alleviate water logging and visualize sponge city construction.

  6. Effect of surface geometry and insolation on temperature profile of green roof in Saint-Petersburg environment

    Directory of Open Access Journals (Sweden)

    С. А. Игнатьев

    2016-08-01

    Full Text Available The paper addresses an issue of creating an environment favorable for the life in megacities by planting vegetation on the rooftops. It also provides information about rooftop greening practices adopted in other countries. The issues of ‘green roof’ building in climatic conditions of Saint Petersburg and roof vegetation impact on the urban ecosystem are examined. Vegetation composition quality- and quantity-wise has been proposed for the roof under research and a 3D model of this roof reflecting its geometric properties has been developed. A structure of roof covering and substrate qualitative composition is presented. An effect of rooftop geometry on the substrate temperature is explored. The annual substrate temperature and moisture content in different parts of the roof have been analyzed. Results of thermal imaging monitoring and insolation modelling for different parts of green roof surface are presented.

  7. Fast high-temperature consolidation of Oxide-Dispersion Strengthened (ODS) steels: process, microstructure, precipitation, properties

    International Nuclear Information System (INIS)

    Boulnat, Xavier

    2014-01-01

    This work aims to lighten the understanding of the behavior of a class of metallic materials called Oxide-Dispersion Strengthened (ODS) ferritic steels. ODS steels are produced by powder metallurgy with various steps including atomization, mechanical alloying and high-temperature consolidation. The consolidation involves the formation of nanoparticles in the steel and various evolutions of the microstructure of the material that are not fully understood. In this thesis, a novel consolidation technique assisted by electric field called 'Spark Plasma Sintering' (SPS) or 'Field-Assisted Sintering Technique' (FAST) was assessed. Excellent mechanical properties were obtained by SPS, comparable to those of conventional hot isostatic pressed (HIP) materials but with much shorter processing time. Also, a broad range of microstructures and thus of tensile strength and ductility were obtained by performing SPS on either milled or atomized powder at different temperatures. However, SPS consolidation failed to avoid heterogeneous microstructure composed of ultrafine-grained regions surrounded by micron grains despite of the rapid consolidation kinetics. A multi-scale characterization allowed to understand and model the evolution of this complex microstructure. An analytical evaluation of the contributing mechanisms can explain the appearance of the complex grain structure and its thermal stability during further heat treatments. Inhomogeneous distribution of plastic deformation in the powder is argued to be the major cause of heterogeneous recrystallization and further grain growth during hot consolidation. Even if increasing the solute content of yttrium, titanium and oxygen does not impede abnormal growth, it permits to control the fraction and the size of the retained ultrafine grains, which is a key-factor to tailor the mechanical properties. Since precipitation through grain boundary pinning plays a significant role on grain growth, a careful

  8. Cladonia lichens on extensive green roofs: evapotranspiration, substrate temperature, and albedo [v1; ref status: indexed, http://f1000r.es/2ha

    Directory of Open Access Journals (Sweden)

    Amy Heim

    2013-12-01

    Full Text Available Green roofs are constructed ecosystems that provide ecosystem services in urban environments. Shallow substrate green roofs subject the vegetation layer to desiccation and other environmental extremes, so researchers have evaluated a variety of stress-tolerant vegetation types for green roof applications. Lichens can be found in most terrestrial habitats.  They are able to survive extremely harsh conditions, including frequent cycles of desiccation and rehydration, nutrient-poor soil, fluctuating temperatures, and high UV intensities. Extensive green roofs (substrate depth <20cm exhibit these harsh conditions, making lichens possible candidates for incorporation into the vegetation layer on extensive green roofs.  In a modular green roof system, we tested the effect of Cladonia lichens on substrate temperature, water loss, and albedo compared to a substrate-only control. Overall, the Cladonia modules had significantly cooler substrate temperatures during the summer and significantly warmer temperatures during the fall.  Additionally, the Cladonia modules lost significantly less water than the substrate-only control. This implies that they may be able to benefit neighboring vascular plant species by reducing water loss and maintaining favorable substrate temperatures.

  9. Effects of melatonin and green-wavelength LED light on the physiological stress and immunity of goldfish, Carassius auratus, exposed to high water temperature.

    Science.gov (United States)

    Jung, Seo Jin; Kim, Na Na; Choi, Young Jae; Choi, Ji Yong; Choi, Young-Ung; Heo, Youn Seong; Choi, Cheol Young

    2016-10-01

    This study investigated the effects of increasing water temperature (22-30 °C) on the physiological stress response and immunity of goldfish, Carassius auratus, and the ability of green light-emitting diode (LED) irradiation or melatonin injections to mitigate this temperature-induced stress. To evaluate the effects of either green-wavelength LED light or melatonin on stress in goldfish, we measured plasma triiodothyronine (T3), thyroxine (T4), and thyroid hormone receptor (TR) mRNA expression; plasma cortisol and glucose; and immunoglobulin M (IgM) and lysozyme mRNA expression. The thyroid hormone activities, TR mRNA expression, and plasma cortisol and glucose were higher in goldfish exposed to high-temperature water, but were lower after exposure to melatonin or green-wavelength LED light. Lysozyme mRNA expression and plasma IgM activity and protein expression were lower after exposure to high water temperatures and higher after melatonin or green-wavelength LED light treatments. Therefore, high water temperature induced stress and decreased immunity; however, green-wavelength LED light and melatonin treatments mitigated the effects of stress and enhanced immunity. The benefits of melatonin decreased with time, whereas those of green-wavelength LED treatment did not.

  10. Global observed long-term changes in temperature and precipitation extremes: A review of progress and limitations in IPCC assessments and beyond

    OpenAIRE

    Lisa V. Alexander

    2016-01-01

    The Intergovernmental Panel on Climate Change (IPCC) first attempted a global assessment of long-term changes in temperature and precipitation extremes in its Third Assessment Report in 2001. While data quality and coverage were limited, the report still concluded that heavy precipitation events had increased and that there had been, very likely, a reduction in the frequency of extreme low temperatures and increases in the frequency of extreme high temperatures. That overall assessment had ch...

  11. Assessing non-linear variation of temperature and precipitation for different growth periods of maize and their impacts on phenology in the Midwest of Jilin Province, China

    Science.gov (United States)

    Guo, Enliang; Zhang, Jiquan; Wang, Yongfang; Alu, Si; Wang, Rui; Li, Danjun; Ha, Si

    2018-05-01

    In the past two decades, the regional climate in China has undergone significant change, resulting in crop yield reduction and complete failure. The goal of this study is to detect the variation of temperature and precipitation for different growth periods of maize and assess their impact on phenology. The daily meteorological data in the Midwest of Jilin Province during 1960-2014 were used in the study. The ensemble empirical mode decomposition method was adopted to analyze the non-linear trend and fluctuation in temperature and precipitation, and the sensitivity of the length of the maize growth period to temperature and precipitation was analyzed by the wavelet cross-transformation method. The results show that the trends of temperature and precipitation change are non-linear for different growth periods of maize, and the average temperature in the sowing-jointing stage was different from that in the other growth stages, showing a slight decrease trend, while the variation amplitude of maximum temperature is smaller than that of the minimum temperature. This indicates that the temperature difference between day and night shows a gradually decreasing trend. Precipitation in the growth period also showed a decreasing non-linear trend, while the inter-annual variability with period of quasi-3-year and quasi-6-year dominated the variation of temperature and precipitation. The whole growth period was shortened by 10.7 days, and the sowing date was advanced by approximately 11 days. We also found that there was a significant resonance period among temperature, precipitation, and phenology. Overall, a negative correlation between phenology and temperature is evident, while a positive correlation with precipitation is exhibited. The results illustrate that the climate suitability for maize has reduced over the past decades.

  12. Greenness and Carbon Stocks of Mangroves: A climate-driven Effect

    Science.gov (United States)

    Lule, A. V.; Colditz, R. R.; Herrera-Silveira, J.; Guevara, M.; Rodriguez-Zuniga, M. T.; Cruz, I.; Ressl, R.; Vargas, R.

    2017-12-01

    Mangroves cover less than 1% of the earth's surface and are one o­­­f the most productive ecosystems of the world. They are highly vulnerable to climate variability due to their sensitivity to environmental changes; therefore, there are scientific and societal needs to designed frameworks to assess mangrove's vulnerability. We study the relationship between climate drivers, canopy greenness and carbon stocks to quantify a potential climate-driven effect on mangrove carbon dynamics. We identify greenness trends and their relationships with climate drivers and carbon stocks throughout 15 years (2001-2015) across mangrove forests of Mexico. We defined several categories for mangroves: a) Arid mangroves with superficial water input (ARsw); b) Humid mangroves with interior or underground water input (HUiw); and c) Humid mangroves with superficial water input (HUsw). We found a positive significant trend of greenness for ARsw and HUsw categories (pmangrove's categories (pmangrove categories showed higher greenness values during winter; which is likely driven by temperature with a lag of -3 to -5 months (r2 > 0.69). Precipitation and temperature drive canopy greenness only across HUsw. Regarding carbon stocks, the HUiw shows the lower amount of aboveground carbon (AGC; 12.7 Mg C ha-1) and the higher belowground carbon (BGC; 219 Mg C ha-1). The HUsw shows the higher amount of AGC (169.5 Mg C ha-1) and the ARsw the lower of BGC (92.4 Mg C ha-1). Climate drivers are better related with canopy greenness and AGC for both humid mangrove categories (r2 > 0.48), while the relationship of BGC and canopy greenness is lower for all categories (r2 mangrove's ecosystem function and environmental services, as well as their potential vulnerability to climate variability.

  13. Future shift of the relative roles of precipitation and temperature in controlling annual runoff in the conterminous United States

    Directory of Open Access Journals (Sweden)

    K. Duan

    2017-11-01

    Full Text Available This study examines the relative roles of climatic variables in altering annual runoff in the conterminous United States (CONUS in the 21st century, using a monthly ecohydrological model (the Water Supply Stress Index model, WaSSI driven with historical records and future scenarios constructed from 20 Coupled Model Intercomparison Project Phase 5 (CMIP5 climate models. The results suggest that precipitation has been the primary control of runoff variation during the latest decades, but the role of temperature will outweigh that of precipitation in most regions if future climate change follows the projections of climate models instead of the historical tendencies. Besides these two key factors, increasing air humidity is projected to partially offset the additional evaporative demand caused by warming and consequently enhance runoff. Overall, the projections from 20 climate models suggest a high degree of consistency on the increasing trends in temperature, precipitation, and humidity, which will be the major climatic driving factors accounting for 43–50, 20–24, and 16–23 % of the runoff change, respectively. Spatially, while temperature rise is recognized as the largest contributor that suppresses runoff in most areas, precipitation is expected to be the dominant factor driving runoff to increase across the Pacific coast and the southwest. The combined effects of increasing humidity and precipitation may also surpass the detrimental effects of warming and result in a hydrologically wetter future in the east. However, severe runoff depletion is more likely to occur in the central CONUS as temperature effect prevails.

  14. Future shift of the relative roles of precipitation and temperature in controlling annual runoff in the conterminous United States

    Science.gov (United States)

    Duan, Kai; Sun, Ge; McNulty, Steven G.; Caldwell, Peter V.; Cohen, Erika C.; Sun, Shanlei; Aldridge, Heather D.; Zhou, Decheng; Zhang, Liangxia; Zhang, Yang

    2017-11-01

    This study examines the relative roles of climatic variables in altering annual runoff in the conterminous United States (CONUS) in the 21st century, using a monthly ecohydrological model (the Water Supply Stress Index model, WaSSI) driven with historical records and future scenarios constructed from 20 Coupled Model Intercomparison Project Phase 5 (CMIP5) climate models. The results suggest that precipitation has been the primary control of runoff variation during the latest decades, but the role of temperature will outweigh that of precipitation in most regions if future climate change follows the projections of climate models instead of the historical tendencies. Besides these two key factors, increasing air humidity is projected to partially offset the additional evaporative demand caused by warming and consequently enhance runoff. Overall, the projections from 20 climate models suggest a high degree of consistency on the increasing trends in temperature, precipitation, and humidity, which will be the major climatic driving factors accounting for 43-50, 20-24, and 16-23 % of the runoff change, respectively. Spatially, while temperature rise is recognized as the largest contributor that suppresses runoff in most areas, precipitation is expected to be the dominant factor driving runoff to increase across the Pacific coast and the southwest. The combined effects of increasing humidity and precipitation may also surpass the detrimental effects of warming and result in a hydrologically wetter future in the east. However, severe runoff depletion is more likely to occur in the central CONUS as temperature effect prevails.

  15. Identification and root cause analysis of cell culture media precipitates in the viral deactivation treatment with high-temperature/short-time method.

    Science.gov (United States)

    Cao, Xiaolin; Stimpfl, Gregory; Wen, Zai-Qing; Frank, Gregory; Hunter, Glenn

    2013-01-01

    High-temperature/short-time (HTST) treatment of cell culture media is one of the proven techniques used in the biopharmaceutical manufacturing industry for the prevention and mitigation of media viral contamination. With the HTST method, the formulated media is pasteurized (virus-deactivated) by heating and pumping the media continuously through the preset high-temperature holding tubes to achieve a specified period of time at a specific temperature. Recently, during the evaluation and implementation of HTST method in multiple Amgen, Inc. manufacturing facilities, media precipitates were observed in the tests of HTST treatments. The media precipitates may have adverse consequences such as clogging the HTST system, altering operating conditions and compromising the efficacy of viral deactivation, and ultimately affecting the media composition and cell growth. In this study, we report the identification of the composition of media precipitates from multiple media HTST runs using combined microspectroscopic methods including Raman, Fourier transform infrared spectroscopy, and scanning electron microscopy with energy-dispersive X-ray spectroscopy. The major composition in the precipitates was determined to be metal phosphates, including calcium phosphate, magnesium phosphate, and iron (III) phosphate. Based on the composition, stoichiometry, and root-cause study of media precipitations, methods were implemented for the mitigation and prevention of the occurrence of the media precipitation. Viral contamination in cell culture media is an important issue in the biopharmaceutical manufacturing industry and may have serious consequences on product quality, efficacy, and safety. High-temperature/short-time (HTST) treatment of cell culture media is one of the proven techniques used in the industry for the prevention and mitigation of media viral contamination. With the HTST method, the formulated media is pasteurized (virus-deactivated) by heating at preset conditions. This

  16. Simulation and spatiotemporal pattern of air temperature and precipitation in Eastern Central Asia using RegCM.

    Science.gov (United States)

    Meng, Xianyong; Long, Aihua; Wu, Yiping; Yin, Gang; Wang, Hao; Ji, Xiaonan

    2018-02-26

    Central Asia is a region that has a large land mass, yet meteorological stations in this area are relatively scarce. To address this data issues, in this study, we selected two reanalysis datasets (the ERA40 and NCEP/NCAR) and downscaled them to 40 × 40 km using RegCM. Then three gridded datasets (the CRU, APHRO, and WM) that were extrapolated from the observations of Central Asian meteorological stations to evaluate the performance of RegCM and analyze the spatiotemporal distribution of precipitation and air temperature. We found that since the 1960s, the air temperature in Xinjiang shows an increasing trend and the distribution of precipitation in the Tianshan area is quite complex. The precipitation is increasing in the south of the Tianshan Mountains (Southern Xinjiang, SX) and decreasing in the mountainous areas. The CRU and WM data indicate that precipitation in the north of the Tianshan Mountains (Northern Xinjiang, NX) is increasing, while the APHRO data show an opposite trend. The downscaled results from RegCM are generally consistent with the extrapolated gridded datasets in terms of the spatiotemporal patterns. We believe that our results can provide useful information in developing a regional climate model in Central Asia where meteorological stations are scarce.

  17. Growing season temperature and precipitation variability and extremes in the U.S. Corn Belt from 1981 to 2012

    Science.gov (United States)

    Dai, S.; Shulski, M.

    2013-12-01

    Climate warming and changes in rainfall patterns and increases in extreme events are resulting in higher risks of crop failures. A greater sense of urgency has been induced to understand the impacts of past climate on crop production in the U.S. As one of the most predominant sources of feed grains, corn is also the main source of U.S. ethanol. In the U.S. Corn Belt, region-scale evaluation on temperature and precipitation variability and extremes during the growing season is not well-documented yet. This study is part of the USDA-funded project 'Useful to Usable: Transforming climate variability and change information for cereal crop producers'. The overall goal of our work is to study the characteristics of average growing season conditions and changes in growing season temperature- and precipitation-based indices that are closely correlated with corn grain yield in the U.S. Corn Belt. The research area is the twelve major Corn Belt states, including IL, IN, IA, KS, MI, MN, MO, NE, OH, SD, ND, and WI. Climate data during 1981-2010 from 132 meteorological stations (elevation ranges from 122 m to 1,202 m) are used in this study, including daily minimum, maximum, and mean temperature, and daily precipitation. From 1981 to 2012, beginning date (BD), ending date (ED), and growing season length (GSL) in the climatological corn growing season are studied. Especially, during the agronomic corn growing season, from Apr to Oct, temperature- and precipitation-based indices are analyzed. The temperature-based indices include: number of days with daily mean temperature below 10°C, number of days with daily mean temperature above 30°C, the sum of growing degree days (GDD) between 10°C to 30°C (GDD10,30, growth range for corn), the sum of growing degree days above 30°C (GDD30+, exposure to harmful warming for corn), the sum of growing degree days between 0°C and 44°C (GDD0,44, survival range limits for corn), the sum of growing degree days between 5°C and 35°C (GDD5

  18. Minimal watering regime impacts on desert adapted green roof plant performance

    Science.gov (United States)

    Kovachich, S.; Pavao-Zuckerman, M.; Templer, S.; Livingston, M.; Stoltz, R.; Smith, S.

    2011-12-01

    Roof tops can cover one-fifth of urban areas and can greatly alter the movement of matter and energy in cities. With traditional roofing methods and materials, roof tops readily absorb heat and as a result, buildings and the surrounding urban area heat to unnaturally high temperatures. It is hypothesized that extensive green roofs would have wide-ranging benefits for arid environments. However, little is known about the cost of water use associated with green roof installations and how to balance energy reduction needs with water costs in this water limited environment. We are conducting a pilot study to test whether a) green roofs with native plants and environmentally-responsible watering regimes will prove successful in arid environments and if b) green roofs provide ecosystem services with responsible water application. Three species of Sonoran Desert natives, Dyssodia pentachaeta (groundcover), Calliandra eriophylla (shrub), and Hesperaloe parviflora (succulent) have been planted in experimental plots [1 m2 model houses and roofs, replicated in triplicate] with two sandy, rocky desert soil mixtures (light mix: 60% expanded shale and heavy mix: organic and sandy mix with 50% shale) at the Biosphere 2 campus near Oracle, Az. The green roofs are watered by two different techniques. The first technique provides "smart watering", the minimal amount of water needed by green roof plants based on precipitation and historical data. The second watering technique is considered heavy and does not take into account environmental conditions. Preliminary data from the experimental plots shows a 30% decrease in daytime roof top temperatures on green roofs and a 10% decrease in interior temperatures in buildings with green roofs. This trend occurs with both watering regimes (heavy and light). This finding suggests that additional irrigation yields no extra heat reduction and energy savings. In order to explain this phenomenon more clearly, we use co-located temperature and

  19. Effects of temperature and precipitation on grassland bird nesting success as mediated by patch size.

    Science.gov (United States)

    Zuckerberg, Benjamin; Ribic, Christine A; McCauley, Lisa A

    2018-02-06

    Grassland birds are declining faster than any other bird guild across North America. Shrinking ranges and population declines are attributed to widespread habitat loss and increasingly fragmented landscapes of agriculture and other land uses that are misaligned with grassland bird conservation. Concurrent with habitat loss and degradation, temperate grasslands have been disproportionally affected by climate change relative to most other terrestrial biomes. Distributions of grassland birds often correlate with gradients in climate, but few researchers have explored the consequences of weather on the demography of grassland birds inhabiting a range of grassland fragments. To do so, we modeled the effects of temperature and precipitation on nesting success rates of 12 grassland bird species inhabiting a range of grassland patches across North America (21,000 nests from 81 individual studies). Higher amounts of precipitation in the preceding year were associated with higher nesting success, but wetter conditions during the active breeding season reduced nesting success. Extremely cold or hot conditions during the early breeding season were associated with lower rates of nesting success. The direct and indirect influence of temperature and precipitation on nesting success was moderated by grassland patch size. The positive effects of precipitation in the preceding year on nesting success were strongest in relatively small grassland patches and had little effect in large patches. Conversely, warm temperatures reduced nesting success in small grassland patches but increased nesting success in large patches. Mechanisms underlying these differences may be patch-size-induced variation in microclimates and predator activity. Although the exact cause is unclear, large grassland patches, the most common metric of grassland conservation, appears to moderate the effects of weather on grassland-bird demography and could be an effective component of climate-change adaptation.

  20. Evaluation of CORDEX-Arctic daily precipitation and temperature-based climate indices over Canadian Arctic land areas

    Science.gov (United States)

    Diaconescu, Emilia Paula; Mailhot, Alain; Brown, Ross; Chaumont, Diane

    2018-03-01

    This study focuses on the evaluation of daily precipitation and temperature climate indices and extremes simulated by an ensemble of 12 Regional Climate Model (RCM) simulations from the ARCTIC-CORDEX experiment with surface observations in the Canadian Arctic from the Adjusted Historical Canadian Climate Dataset. Five global reanalyses products (ERA-Interim, JRA55, MERRA, CFSR and GMFD) are also included in the evaluation to assess their potential for RCM evaluation in data sparse regions. The study evaluated the means and annual anomaly distributions of indices over the 1980-2004 dataset overlap period. The results showed that RCM and reanalysis performance varied with the climate variables being evaluated. Most RCMs and reanalyses were able to simulate well climate indices related to mean air temperature and hot extremes over most of the Canadian Arctic, with the exception of the Yukon region where models displayed the largest biases related to topographic effects. Overall performance was generally poor for indices related to cold extremes. Likewise, only a few RCM simulations and reanalyses were able to provide realistic simulations of precipitation extreme indicators. The multi-reanalysis ensemble provided superior results to individual datasets for climate indicators related to mean air temperature and hot extremes, but not for other indicators. These results support the use of reanalyses as reference datasets for the evaluation of RCM mean air temperature and hot extremes over northern Canada, but not for cold extremes and precipitation indices.

  1. Weather extremes and the Romans - A marine palynological perspective on Italian temperature and precipitation between 200 BC and 500 AD

    Science.gov (United States)

    Zonneveld, Karin; Clotten, Caroline; Chen, Liang

    2015-04-01

    Sediments of a tephra-dated marine sediment core located at the distal part of the Po-river discharge plume (southern Italy) have been studied with a three annual resolution. Based on the variability in the dinoflagellate cyst content detailed reconstructions have been established of variability in precipitation related river discharge rates and local air temperature. Furthermore about the variability in distort water quality has been reconstructed. We show that both precipitation and temperature signals vary in tune with cyclic changes in solar insolation. On top of these cyclic changes, short term extremes in temperature and precipitation can be observed that can be interpreted to reflect periods of local weather extremes. Comparison of our reconstructions with historical information suggest that times of high temperatures and maximal precipitation corresponds to the period of maximal expansion of the Roman Empire. We have strong indications that at this time discharge waters might have contained higher nutrient concentrations compared to previous and later time intervals suggesting anthropogenic influence of the water quality. First pilot-results suggest that the decrease in temperature reconstructed just after the "Roman Optimum" corresponds to an increase in numbers of armored conflicts between the Roman and German cultures. Furthermore we observe a resemblance in timing of short-term intervals with cold weather spells during the early so called "Dark-Age-Period" to correspond to epidemic/pandemic events in Europe.

  2. Downscaling RCP8.5 daily temperatures and precipitation in Ontario using localized ensemble optimal interpolation (EnOI) and bias correction

    Science.gov (United States)

    Deng, Ziwang; Liu, Jinliang; Qiu, Xin; Zhou, Xiaolan; Zhu, Huaiping

    2017-10-01

    A novel method for daily temperature and precipitation downscaling is proposed in this study which combines the Ensemble Optimal Interpolation (EnOI) and bias correction techniques. For downscaling temperature, the day to day seasonal cycle of high resolution temperature of the NCEP climate forecast system reanalysis (CFSR) is used as background state. An enlarged ensemble of daily temperature anomaly relative to this seasonal cycle and information from global climate models (GCMs) are used to construct a gain matrix for each calendar day. Consequently, the relationship between large and local-scale processes represented by the gain matrix will change accordingly. The gain matrix contains information of realistic spatial correlation of temperature between different CFSR grid points, between CFSR grid points and GCM grid points, and between different GCM grid points. Therefore, this downscaling method keeps spatial consistency and reflects the interaction between local geographic and atmospheric conditions. Maximum and minimum temperatures are downscaled using the same method. For precipitation, because of the non-Gaussianity issue, a logarithmic transformation is used to daily total precipitation prior to conducting downscaling. Cross validation and independent data validation are used to evaluate this algorithm. Finally, data from a 29-member ensemble of phase 5 of the Coupled Model Intercomparison Project (CMIP5) GCMs are downscaled to CFSR grid points in Ontario for the period from 1981 to 2100. The results show that this method is capable of generating high resolution details without changing large scale characteristics. It results in much lower absolute errors in local scale details at most grid points than simple spatial downscaling methods. Biases in the downscaled data inherited from GCMs are corrected with a linear method for temperatures and distribution mapping for precipitation. The downscaled ensemble projects significant warming with amplitudes of 3

  3. Future Temperatures and Precipitations in the Arid Northern-Central Chile: A Multi-Model Downscaling Approach

    Science.gov (United States)

    Souvignet, M.; Heinrich, J.

    2010-03-01

    Downscaling of global climate outputs is necessary to transfer projections of potential climate change scenarios to local levels. This is of special interest to dry mountainous areas, which are particularly vulnerable to climate change due to risks of reduced freshwater availability. These areas play a key role for hydrology since they usually receive the highest local precipitation rates stored in form of snow and glaciers. In the central-northern Chile (Norte Chico, 26-33ºS), where agriculture still serves as a backbone of the economy as well as ensures the well being of people, the knowledge of water resources availability is essential. The region is characterised by a semiarid climate with a mean annual precipitation inferior to 100mm. Moreover, the local climate is also highly influenced by the ENSO phenomenon, which accounts for the strong inter-annual variability in precipitation patterns. Although historical and spatially extensive precipitation data in the headwaters of the basins in this region are not readily available, records at coastal stations show worrisome trends. For instance, the average precipitation in La Serena, the most important city located in the Coquimbo Region, has decreased dramatically in the past 100 years. The 30-year monthly average has decreased from 170 mm in the early 20th century to values less than 80 mm nowadays. Climate Change is expected to strengthen this pattern in the region, and therefore strongly influence local hydrological patterns. The objectives of this study are i) to develop climate change scenarios (2046-2099) for the Norte Chico using multi-model predictions in terms of temperatures and precipitations, and ii) to compare the efficiency of two downscaling techniques in arid mountainous regions. In addition, this study aims at iii) providing decision makers with sound analysis of potential impact of Climate Change on streamflow in the region. For the present study, future local climate scenarios were developed

  4. Projecting changes in regional temperature and precipitation extremes in the United States

    OpenAIRE

    Justin T. Schoof; Scott M. Robeson

    2016-01-01

    Regional and local climate extremes, and their impacts, result from the multifaceted interplay between large-scale climate forcing, local environmental factors (physiography), and societal vulnerability. In this paper, we review historical and projected changes in temperature and precipitation extremes in the United States, with a focus on strengths and weaknesses of (1) commonly used definitions for extremes such as thresholds and percentiles, (2) statistical approaches to quantifying change...

  5. Characterization of γ- Al2O3 nanopowders synthesized by Co-precipitation method

    International Nuclear Information System (INIS)

    Jbara, Ahmed S.; Othaman, Zulkafli; Ati, Ali A.; Saeed, M.A.

    2017-01-01

    Co-precipitation technique has been used to synthesize gamma-Al 2 O 3 (γ-Al 2 O 3 ) nanopowders under annealing temperature effect. The crystalline phase and purity for the prepared powder were characterized by different spectroscopy techniques. XRD analysis confirms the gamma phase of alumina nanopowders with particle diameter ranging from 6 to 24 nm, which confirms the quantum dots formation, which is also supported by the BET measurement. The surface area of the prepared nanopowders is in the range of 109–367 m 2 /g. Morphology analysis indicates that γ-Al 2 O 3 nanopowders are consisted of grains almost spherical in shape. Some agglomeration of nanoparticles occurs, which become more regular hexagonal shaped with the increasing annealing temperature. The small nanoparticles size and the high surface area from a simple procedure for preparing γ-Al 2 O 3 may make it more suitable for use as an adsorbent for malachite green. - Highlights: • Co-precipitation technique is used to synthesize gamma- Al 2 O 3 nanopowders. • Pure gamma- Al 2 O 3 phase was obtained having maximum nanoparticle size is 24 nm. • The quantum dots were formed inside powder. • High surface area of nanopowders at the low annealing temperature. • Increasing annealing temperature causes the hexagonal agglomeration shape.

  6. Temperature sensitive molecularly imprinted microspheres for solid-phase dispersion extraction of malachite green, crystal violet and their leuko metabolites

    International Nuclear Information System (INIS)

    Tan, Lei; Chen, Kuncai; He, Rong; Peng, Rongfei; Huang, Cong

    2016-01-01

    This article demonstrates the feasibility of an alternative strategy for producing temperature sensitive molecularly imprinted microspheres (MIMs) for solid-phase dispersion extraction of malachite green, crystal violet and their leuko metabolites. Thermo-sensitive MIMs can change their structure following temperature stimulation. This allows capture and release of target molecules to be controlled by temperature. The fabrication technique provides surface molecular imprinting in acetonitrile using vinyl modified silica microspheres as solid supports, methacrylic acid and N-isopropyl acrylamide as the functional monomers, ethyleneglycol dimethacrylate as the cross-linker, and malachite green as the template. After elution of the template, the MIMs can be used for fairly group-selective solid phase dispersion extraction of malachite green, crystal violet, leucomalachite green, and leucocrystal violet from homogenized fish samples at a certain temperature. Following centrifugal separation of the microspheres, the analytes were eluted with a 95:5 mixture of acetonitrile and formic acid, and then quantified by ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) with isotope internal calibration. The detection limits for malachite green, crystal violet and their metabolites typically are 30 ng·kg −1 . Positive samples were identified by UHPLC-MS/MS in the positive ionization mode with multiple reaction monitoring. The method was applied to the determination of the dyes and the respective leuko dyes in fish samples, and accuracy and precision were validated by comparative analysis of the samples by using aluminum neutral columns. (author)

  7. The effects of annealing temperature and cooling rate on carbide precipitation behavior in H13 hot-work tool steel

    International Nuclear Information System (INIS)

    Kang, Minwoo; Park, Gyujin; Jung, Jae-Gil; Kim, Byung-Hoon; Lee, Young-Kook

    2015-01-01

    Highlights: • Unexpected Mo carbides formed during slow cooling from low annealing temperatures. • Mo carbides formed during the migration of Mo for a transition of Cr-rich carbide. • Mo carbides were precipitated at the boundaries of M 7 C 3 carbides and ferrite grains. • Annealing conditions for the precipitation of Mo carbides were discussed. - Abstract: The precipitation behavior of H13 hot-work tool steel was investigated as a function of both annealing temperature and cooling rate through thermodynamic calculations and microstructural analyses using transmission and scanning electron microscope and a dilatometer. The V-rich MC carbide and Cr-rich M 7 C 3 and M 23 C 6 carbides were observed in all annealed specimens regardless of annealing and cooling conditions, as expected from an equilibrium phase diagram of the steel used. However, Mo-rich M 2 C and M 6 C carbides were unexpectedly precipitated at a temperature between 675 °C and 700 °C during slow cooling at a rate of below 0.01 °C/s from the annealing temperatures of 830 °C and below. The solubility of Mo in both M 7 C 3 and ferrite reduces with decreasing temperature during cooling. Mo atoms diffuse out of both M 7 C 3 and ferrite, and accumulate locally at the interface between M 7 C 3 and ferrite. Mo carbides were form at the interface of M 7 C 3 carbides during the transition of Cr-rich M 7 C 3 to stable M 23 C 6

  8. Cladonia lichens on extensive green roofs: evapotranspiration, substrate temperature, and albedo [v2; ref status: indexed, http://f1000r.es/2v4

    Directory of Open Access Journals (Sweden)

    Amy Heim

    2014-01-01

    Full Text Available Green roofs are constructed ecosystems that provide ecosystem services in urban environments. Shallow substrate green roofs subject the vegetation layer to desiccation and other environmental extremes, so researchers have evaluated a variety of stress-tolerant vegetation types for green roof applications. Lichens can be found in most terrestrial habitats.  They are able to survive extremely harsh conditions, including frequent cycles of desiccation and rehydration, nutrient-poor soil, fluctuating temperatures, and high UV intensities. Extensive green roofs (substrate depth <20cm exhibit these harsh conditions, making lichens possible candidates for incorporation into the vegetation layer on extensive green roofs.  In a modular green roof system, we tested the effect of Cladonia lichens on substrate temperature, water loss, and albedo compared to a substrate-only control. Overall, the Cladonia modules had significantly cooler substrate temperatures during the summer and significantly warmer temperatures during the fall.  Additionally, the Cladonia modules lost significantly less water than the substrate-only control. This implies that they may be able to benefit neighboring vascular plant species by reducing water loss and maintaining favorable substrate temperatures.

  9. Variability and predictability of decadal mean temperature and precipitation over China in the CCSM4 last millennium simulation

    Science.gov (United States)

    Ying, Kairan; Frederiksen, Carsten S.; Zheng, Xiaogu; Lou, Jiale; Zhao, Tianbao

    2018-02-01

    The modes of variability that arise from the slow-decadal (potentially predictable) and intra-decadal (unpredictable) components of decadal mean temperature and precipitation over China are examined, in a 1000 year (850-1850 AD) experiment using the CCSM4 model. Solar variations, volcanic aerosols, orbital forcing, land use, and greenhouse gas concentrations provide the main forcing and boundary conditions. The analysis is done using a decadal variance decomposition method that identifies sources of potential decadal predictability and uncertainty. The average potential decadal predictabilities (ratio of slow-to-total decadal variance) are 0.62 and 0.37 for the temperature and rainfall over China, respectively, indicating that the (multi-)decadal variations of temperature are dominated by slow-decadal variability, while precipitation is dominated by unpredictable decadal noise. Possible sources of decadal predictability for the two leading predictable modes of temperature are the external radiative forcing, and the combined effects of slow-decadal variability of the Arctic oscillation (AO) and the Pacific decadal oscillation (PDO), respectively. Combined AO and PDO slow-decadal variability is associated also with the leading predictable mode of precipitation. External radiative forcing as well as the slow-decadal variability of PDO are associated with the second predictable rainfall mode; the slow-decadal variability of Atlantic multi-decadal oscillation (AMO) is associated with the third predictable precipitation mode. The dominant unpredictable decadal modes are associated with intra-decadal/inter-annual phenomena. In particular, the El Niño-Southern Oscillation and the intra-decadal variability of the AMO, PDO and AO are the most important sources of prediction uncertainty.

  10. Hydride precipitation crack propagation in zircaloy cladding during a decreasing temperature history

    International Nuclear Information System (INIS)

    Stout, R.B.

    2001-01-01

    An assessment of safety, design, and cost tradeoff issues for short (ten to fifty years) and longer (fifty to hundreds of years) interim dry storage of spent nuclear fuel in Zircaloy rods shall address potential failures of the Zircaloy cladding caused by the precipitation response of zirconium hydride platelets. To perform such assessment analyses rigorously and conservatively will be necessarily complex and difficult. For Zircaloy cladding, a model for zirconium hydride induced crack propagation velocity was developed for a decreasing temperature field and for hydrogen, temperature, and stress dependent diffusive transport of hydrogen to a generic hydride platelet at a crack tip. The development of the quasi-steady model is based on extensions of existing models for hydride precipitation kinetics for an isolated hydride platelet at a crack tip. An instability analysis model of hydride-crack growth was developed using existing concepts in a kinematic equation for crack propagation at a constant thermodynamic crack potential subject to brittle fracture conditions. At the time an instability is initiated, the crack propagation is no longer limited by hydride growth rate kinetics, but is then limited by stress rates. The model for slow hydride-crack growth will be further evaluated using existing available data. (authors)

  11. Hydride precipitation crack propagation in zircaloy cladding during a decreasing temperature history

    Energy Technology Data Exchange (ETDEWEB)

    Stout, R.B. [California Univ., Livermore, CA (United States). Lawrence Livermore National Lab

    2001-07-01

    An assessment of safety, design, and cost tradeoff issues for short (ten to fifty years) and longer (fifty to hundreds of years) interim dry storage of spent nuclear fuel in Zircaloy rods shall address potential failures of the Zircaloy cladding caused by the precipitation response of zirconium hydride platelets. To perform such assessment analyses rigorously and conservatively will be necessarily complex and difficult. For Zircaloy cladding, a model for zirconium hydride induced crack propagation velocity was developed for a decreasing temperature field and for hydrogen, temperature, and stress dependent diffusive transport of hydrogen to a generic hydride platelet at a crack tip. The development of the quasi-steady model is based on extensions of existing models for hydride precipitation kinetics for an isolated hydride platelet at a crack tip. An instability analysis model of hydride-crack growth was developed using existing concepts in a kinematic equation for crack propagation at a constant thermodynamic crack potential subject to brittle fracture conditions. At the time an instability is initiated, the crack propagation is no longer limited by hydride growth rate kinetics, but is then limited by stress rates. The model for slow hydride-crack growth will be further evaluated using existing available data. (authors)

  12. Region-specific sensitivity of anemophilous pollen deposition to temperature and precipitation.

    Directory of Open Access Journals (Sweden)

    Timme H Donders

    Full Text Available Understanding relations between climate and pollen production is important for several societal and ecological challenges, importantly pollen forecasting for pollinosis treatment, forensic studies, global change biology, and high-resolution palaeoecological studies of past vegetation and climate fluctuations. For these purposes, we investigate the role of climate variables on annual-scale variations in pollen influx, test the regional consistency of observed patterns, and evaluate the potential to reconstruct high-frequency signals from sediment archives. A 43-year pollen-trap record from the Netherlands is used to investigate relations between annual pollen influx, climate variables (monthly and seasonal temperature and precipitation values, and the North Atlantic Oscillation climate index. Spearman rank correlation analysis shows that specifically in Alnus, Betula, Corylus, Fraxinus, Quercus and Plantago both temperature in the year prior to (T-1, as well as in the growing season (T, are highly significant factors (TApril rs between 0.30 [P<0.05[ and 0.58 [P<0.0001]; TJuli-1 rs between 0.32 [P<0.05[ and 0.56 [P<0.0001] in the annual pollen influx of wind-pollinated plants. Total annual pollen prediction models based on multiple climate variables yield R2 between 0.38 and 0.62 (P<0.0001. The effect of precipitation is minimal. A second trapping station in the SE Netherlands, shows consistent trends and annual variability, suggesting the climate factors are regionally relevant. Summer temperature is thought to influence the formation of reproductive structures, while temperature during the flowering season influences pollen release. This study provides a first predictive model for seasonal pollen forecasting, and also aides forensic studies. Furthermore, variations in pollen accumulation rates from a sub-fossil peat deposit are comparable with the pollen trap data. This suggests that high frequency variability pollen records from natural

  13. Detection of spatio-temporal variability of air temperature and precipitation based on long-term meteorological station observations over Tianshan Mountains, Central Asia

    Science.gov (United States)

    Xu, Min; Kang, Shichang; Wu, Hao; Yuan, Xu

    2018-05-01

    As abundant distribution of glaciers and snow, the Tianshan Mountains are highly vulnerable to changes in climate. Based on meteorological station records during 1960-2016, we detected the variations of air temperature and precipitation by using non-parametric method in the different sub-regions and different elevations of the Tianshan Mountains. The mutations of climate were investigated by Mann-Kendall abrupt change test in the sub-regions. The periodicity is examined by wavelet analysis employing a chi-square test and detecting significant time sections. The results show that the Tianshan Mountains experienced an overall rapid warming and wetting during study period, with average warming rate of 0.32 °C/10a and wet rate of 5.82 mm/10a, respectively. The annual and seasonal spatial variation of temperature showed different scales in different regions. The annual precipitation showed non-significant upward trend in 20 stations, and 6 stations showed a significant upward trend. The temperatures in the East Tianshan increased most rapidly at rates of 0.41 °C/10a. The increasing magnitudes of annual precipitation were highest in the Boertala Vally (8.07 mm/10a) and lowest in the East Tianshan (2.64 mm/10a). The greatest and weakest warming was below 500 m (0.42 °C/10a) and elevation of 1000-1500 m (0.23 °C/10a), respectively. The increasing magnitudes of annual precipitation were highest in the elevation of 1500 m-2000 m (9.22 mm/10a) and lowest in the elevation of below 500 m (3.45 mm/10a). The mutations of annual air temperature and precipitation occurred in 1995 and 1990, respectively. The large atmospheric circulation influenced on the mutations of climate. The significant periods of air temperature were 2.4-4.1 years, and annual precipitation was 2.5-7.4 years. Elevation dependency of temperature trend magnitude was not evidently in the Tianshan Mountains. The annual precipitation wetting trend was amplified with elevation in summer and autumn. The strong

  14. Advantages of a Vertical High-Resolution Distributed-Temperature-Sensing System Used to Evaluate the Thermal Behavior of Green Roofs

    Science.gov (United States)

    Hausner, M. B.; Suarez, F. I.; Cousiño, J. A.; Victorero, F.; Bonilla, C. A.; Gironas, J. A.; Vera, S.; Bustamante, W.; Rojas, V.; Leiva, E.; Pasten, P.

    2015-12-01

    Technological innovations used for sustainable urban development, green roofs offer a range of benefits, including reduced heat island effect, rooftop runoff, roof surface temperatures, energy consumption, and noise levels inside buildings, as well as increased urban biodiversity. Green roofs feature layered construction, with the most important layers being the vegetation and the substrate layers located above the traditional roof. These layers provide both insulation and warm season cooling by latent heat flux, reducing the thermal load to the building. To understand and improve the processes driving this thermal energy reduction, it is important to observe the thermal dynamics of a green roof at the appropriate spatial and temporal scales. Traditionally, to observe the thermal behavior of green roofs, a series of thermocouples have been installed at discrete depths within the layers of the roof. Here, we present a vertical high-resolution distributed-temperature-sensing (DTS) system installed in different green roof modules of the Laboratory of Vegetated Infrastructure for Buildings (LIVE -its acronym in Spanish) of the Pontifical Catholic University of Chile. This DTS system allows near-continuous measurement of the thermal profile at spatial and temporal resolutions of approximately 1 cm and 30 s, respectively. In this investigation, the temperature observations from the DTS system are compared with the measurements of a series of thermocouples installed in the green roofs. This comparison makes it possible to assess the value of thermal observations at better spatial and temporal resolutions. We show that the errors associated with lower resolution observations (i.e., from the thermocouples) are propagated in the calculations of the heat fluxes through the different layers of the green roof. Our results highlight the value of having a vertical high-resolution DTS system to observe the thermal dynamics in green roofs.

  15. Regional scaling of annual mean precipitation and water availability with global temperature change

    Science.gov (United States)

    Greve, Peter; Gudmundsson, Lukas; Seneviratne, Sonia I.

    2018-03-01

    Changes in regional water availability belong to the most crucial potential impacts of anthropogenic climate change, but are highly uncertain. It is thus of key importance for stakeholders to assess the possible implications of different global temperature thresholds on these quantities. Using a subset of climate model simulations from the fifth phase of the Coupled Model Intercomparison Project (CMIP5), we derive here the sensitivity of regional changes in precipitation and in precipitation minus evapotranspiration to global temperature changes. The simulations span the full range of available emission scenarios, and the sensitivities are derived using a modified pattern scaling approach. The applied approach assumes linear relationships on global temperature changes while thoroughly addressing associated uncertainties via resampling methods. This allows us to assess the full distribution of the simulations in a probabilistic sense. Northern high-latitude regions display robust responses towards wetting, while subtropical regions display a tendency towards drying but with a large range of responses. Even though both internal variability and the scenario choice play an important role in the overall spread of the simulations, the uncertainty stemming from the climate model choice usually accounts for about half of the total uncertainty in most regions. We additionally assess the implications of limiting global mean temperature warming to values below (i) 2 K or (ii) 1.5 K (as stated within the 2015 Paris Agreement). We show that opting for the 1.5 K target might just slightly influence the mean response, but could substantially reduce the risk of experiencing extreme changes in regional water availability.

  16. Dynamic precipitation of nickel-based superalloys undergoing severe deformation below the solvus temperature

    Energy Technology Data Exchange (ETDEWEB)

    Nowotnik, Andrzej; Rokicki, Pawel; Mrowka-Nowotnik, Grazyna; Sieniawski, Jan [Rzeszow Univ. of Technology (Poland). Dept. of Material Science

    2015-07-15

    The authors performed uniaxial compression tests of nickel-based superalloys: single crystal CMSX-4, also precipitation hardened; Inconel 718 and X750, at temperatures below the γ' solvus, in order to study the effect of temperature and strain rate on their flow stress and microstructural development. On the basis of the obtained flow stress values, the activation energy of a high-temperature deformation process was estimated. Microstructural observations of the deformed samples at high temperatures, previously solution heat treated and aged CMSX-4 and Inconel alloys revealed non-uniform deformation effects. Distribution of either molybdenum- or niobium-rich carbides was found to be affected by localized flow within the investigated strain range at relatively low deformation temperatures, 720-850 C. Microstructural examination of the alloys also showed that shear banding and cavity growth were responsible for the decrease in flow stress and a specimen fracture at larger strains.

  17. Studying the Association between Green Space Characteristics and Land Surface Temperature for Sustainable Urban Environments: An Analysis of Beijing and Islamabad

    Directory of Open Access Journals (Sweden)

    Shahid Naeem

    2018-01-01

    Full Text Available Increasing trends of urbanization lead to vegetation degradation in big cities and affect the urban thermal environment. This study investigated (1 the cooling effect of urban green space spatial patterns on Land Surface Temperature (LST; (2 how the surrounding environment influences the green space cool islands (GCI, and vice versa. The study was conducted in two Asian capitals: Beijing, China and Islamabad, Pakistan by utilizing Gaofen-1 (GF-1 and Landsat-8 satellite imagery. Pearson’s correlation and normalized mutual information (NMI were applied to investigate the relationship between green space characteristics and LST. Landscape metrics of green spaces including Percentage of Landscape (PLAND, Patch Density (PD, Edge Density (ED, and Landscape Shape Index (LSI were selected to calculate the spatial patterns of green spaces, whereas GCI indicators were defined by Green Space Range (GR, Temperature Difference (TD, and Temperature Gradient (TG. The results indicate that both vegetation composition and configuration influence LST distributions; however, vegetation composition appeared to have a slightly greater effect. The cooling effect can be produced more effectively by increasing green space percentage, planting trees in large patches with equal distribution, and avoiding complex-shaped green spaces. The GCI principle indicates that LST can be decreased by increasing the green space area, increasing the water body fraction, or by decreasing the fraction of impervious surfaces. GCI can also be strengthened by decreasing the fraction of impervious surfaces and increasing the fraction of water body or vegetation in the surrounding environment. The cooling effect of vegetation and water could be explained based on their thermal properties. Beijing has already enacted the green-wedge initiative to increase the vegetation canopy. While designing the future urban layout of Islamabad, the construction of artificial lakes within the urban green

  18. Coprecipitation of Arsenate and Arsenite with Green Rust Minerals

    Science.gov (United States)

    The objectives of this experiment were to evaluate the extent and nature of arsenic co-precipitation with green rusts and to examine the influence of arsenic incorporation on the mineralogy of formed solid phases. Stoichiometric green rusts were obtained by coprecipitation of fe...

  19. Future weather types and their influence on mean and extreme climate indices for precipitation and temperature in Central Europe

    Directory of Open Access Journals (Sweden)

    Ulf Riediger

    2014-09-01

    Full Text Available In Central Europe, the spatial and temporal distributions of precipitation and temperature are determined by the occurrence of major weather types. In this paper, we examine climate indices (i.e. mean values or hot, cold, wet and dry days for different weather types in a recent (1971–2000 and future climate (2070–2099. The weather types are classified objectively for the control run and for the A1B scenario with an ensemble of eight global climate simulations (GCM to be compared with different reanalyses. To derive climate indices, the high-resolution, regionalized reference dataset HYRAS and an ensemble of nine regional climate simulations (RCM are used. Firstly, the reliability of simulated weather patterns and their climate indices are tested in the control period. The reanalyses circulation climatology can be reproduced well by the GCM ensemble mean. For temperature and precipitation, each climate index is characterized and evaluated in terms of defined weather patterns. The comparison of HYRAS and RCM data show reliable mean temperature values with differences between weather classes by +2$+2$ to -6$-6$ °C during winter (13 to 19 °C in summer. The analysis of observed and simulated precipitation reveal that mean winter precipitation is significantly influenced by the direction of air flow, while in summer, mesoscale atmospheric patterns of cyclonic rotation play a larger role. Secondly, the analysis of potential future changes simulated by the RCM ensemble were able to demonstrate that weather type changes, superior climate trends (such as mean warming and their interaction lead to major changes for precipitation and temperature in Central Europe. While temperature differences between cold and warm weather types are nearly stable over time, the ensemble temperature changes (with a range of +2$+2$ to +4$+4$ °C reinforce warm/hot conditions in the future winter and summer. Milder, wetter winters can be explained by an increased

  20. Historical effects of temperature and precipitation on California crop yields

    Energy Technology Data Exchange (ETDEWEB)

    Lobell, D.B. [Energy and Environment Directorate, Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Cahill, K.N. [Interdisciplinary Graduate Program in Environment and Resources, Stanford University, Stanford, CA 94305 (United States); Field, C.B. [Department of Global Ecology, Carnegie Institution, Stanford, CA 94305 (United States)

    2007-03-15

    For the 1980-2003 period, we analyzed the relationship between crop yield and three climatic variables (minimum temperature, maximum temperature, and precipitation) for 12 major Californian crops: wine grapes, lettuce, almonds, strawberries, table grapes, hay, oranges, cotton, tomatoes, walnuts, avocados, and pistachios. The months and climatic variables of greatest importance to each crop were used to develop regressions relating yield to climatic conditions. For most crops, fairly simple equations using only 2-3 variables explained more than two-thirds of observed yield variance. The types of variables and months identified suggest that relatively poorly understood processes such as crop infection, pollination, and dormancy may be important mechanisms by which climate influences crop yield. Recent climatic trends have had mixed effects on crop yields, with orange and walnut yields aided, avocado yields hurt, and most crops little affected by recent climatic trends. Yield-climate relationships can provide a foundation for forecasting crop production within a year and for projecting the impact of future climate changes.

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

    Directory of Open Access Journals (Sweden)

    Benjamin I. Cook

    2013-05-01

    Full Text Available 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

  2. The effects of liquid-coating mulch spray on growth, yield and undersoil temperature in komatsuna greens (Brassica rapa L.)

    International Nuclear Information System (INIS)

    Sato, T.; Shiobara, Y.; Omori, A.; Yoshino, M.; Kuba, K.; Takada, K.; Ikeda, Y.; Motoki, S.; Ogura, S.; Kudo, M.

    2009-01-01

    This experiment was intended to examine the effects of a black liquid-coating mulch on the growth and yield of komatsuna greens. Four treatments (1, 0.5, 0.25 and 0 L/square m) of spray amount were tested in combination with seeding date (Sep. 21sup(st), Oct. 5sup(th), Oct. 20sup(th) in an open field and the Jan. 22sup(nd) in a plastic film house). As a result, we found this liquid-coating mulch increased yields of komatsuna greens, unrelated to the spray amount. Generally, the daily highest soil temperature (-5 cm) under the mulching exceeded the control in every treatment however the daily lowest temperature was less than control except in the case of seeding at Sep. 21sup(st). These phenomena were remarkable in the early stage of growing and the differences in temperature between the control and mulch treatments were reduced during the growth. There was no significant difference in the hourly-integrated temperature during the first 10 days between the 4 treatments on same seeding date. These findings suggest that the expansion of the daily soil temperature range contributed the increased yields of komatsuna greens

  3. Regional climate assessment of precipitation and temperature in Southern Punjab (Pakistan) using SimCLIM climate model for different temporal scales

    Science.gov (United States)

    Amin, Asad; Nasim, Wajid; Mubeen, Muhammad; Sarwar, Saleem; Urich, Peter; Ahmad, Ashfaq; Wajid, Aftab; Khaliq, Tasneem; Rasul, Fahd; Hammad, Hafiz Mohkum; Rehmani, Muhammad Ishaq Asif; Mubarak, Hussani; Mirza, Nosheen; Wahid, Abdul; Ahamd, Shakeel; Fahad, Shah; Ullah, Abid; Khan, Mohammad Nauman; Ameen, Asif; Amanullah; Shahzad, Babar; Saud, Shah; Alharby, Hesham; Ata-Ul-Karim, Syed Tahir; Adnan, Muhammad; Islam, Faisal; Ali, Qazi Shoaib

    2018-01-01

    Unbalanced climate during the last decades has created spatially alarming and destructive situations in the world. Anomalies in temperature and precipitation enhance the risks for crop production in large agricultural region (especially the Southern Punjab) of Pakistan. Detailed analysis of historic weather data (1980-2011) record helped in creating baseline data to compare with model projection (SimCLIM) for regional level. Ensemble of 40 GCMs used for climatic projections with greenhouse gas (GHG) representative concentration pathways (RCP-4.5, 6.0, 8.5) was selected on the baseline comparison and used for 2025 and 2050 climate projection. Precipitation projected by ensemble and regional weather observatory at baseline showed highly unpredictable nature while both temperature extremes showed 95 % confidence level on a monthly projection. Percentage change in precipitation projected by model with RCP-4.5, RCP-6.0, and RCP-8.5 showed uncertainty 3.3 to 5.6 %, 2.9 to 5.2 %, and 3.6 to 7.9 % for 2025 and 2050, respectively. Percentage change of minimum temperature from base temperature showed that 5.1, 4.7, and 5.8 % for 2025 and 9.0, 8.1, and 12.0 % increase for projection year 2050 with RCP-4.5, 6.0, and 8.5 and maximum temperature 2.7, 2.5, and 3.0 % for 2025 and 4.7, 4.4, and 6.4 % for 2050 will be increased with RCP-4.5, 6.0, and 8.5, respectively. Uneven increase in precipitation and asymmetric increase in temperature extremes in future would also increase the risk associated with management of climatic uncertainties. Future climate projection will enable us for better risk management decisions.

  4. The role of summer precipitation and summer temperature in establishment and growth of dwarf shrub Betula nana in northeast Siberian tundra

    DEFF Research Database (Denmark)

    Li, Bingxi; Heijmans, Monique M P D; Berendse, Frank

    2016-01-01

    It is widely believed that deciduous tundra-shrub dominance is increasing in the pan-Arctic region, mainly due to rising temperature. We sampled dwarf birch (Betula nana L.) at a northeastern Siberian tundra site and used dendrochronological methods to explore the relationship between climatic...... variables and local shrub dominance. We found that establishment of shrub ramets was positively related to summer precipitation, which implies that the current high dominance of B. nana at our study site could be related to high summer precipitation in the period from 1960 to 1990. The results confirmed...... that early summer temperature is most influential to annual growth rates of B. nana. In addition, summer precipitation stimulated shrub growth in years with warm summers, suggesting that B. nana growth may be co-limited by summer moisture supply. The dual controlling role of temperature and summer...

  5. Effects of temperature and precipitation variability on the risk of violence in sub-Saharan Africa, 1980-2012.

    Science.gov (United States)

    O'Loughlin, John; Linke, Andrew M; Witmer, Frank D W

    2014-11-25

    Ongoing debates in the academic community and in the public policy arena continue without clear resolution about the significance of global climate change for the risk of increased conflict. Sub-Saharan Africa is generally agreed to be the region most vulnerable to such climate impacts. Using a large database of conflict events and detailed climatological data covering the period 1980-2012, we apply a multilevel modeling technique that allows for a more nuanced understanding of a climate-conflict link than has been seen heretofore. In the aggregate, high temperature extremes are associated with more conflict; however, different types of conflict and different subregions do not show consistent relationship with temperature deviations. Precipitation deviations, both high and low, are generally not significant. The location and timing of violence are influenced less by climate anomalies (temperature or precipitation variations from normal) than by key political, economic, and geographic factors. We find important distinctions in the relationship between temperature extremes and conflict by using multiple methods of analysis and by exploiting our time-series cross-sectional dataset for disaggregated analyses.

  6. A European daily high-resolution gridded dataset of surface temperature and precipitation for 1950-2006

    NARCIS (Netherlands)

    Haylock, M.; Hofstra, N.; Klein Tank, A.; Klok, L.; Jones, P.; New, M.

    2008-01-01

    We present a European land-only daily high-resolution gridded data set for precipitation and minimum, maximum, and mean surface temperature for the period 1950–2006. This data set improves on previous products in its spatial resolution and extent, time period, number of contributing stations, and

  7. Green's function method with consideration of temperature dependent material properties for fatigue monitoring of nuclear power plants

    International Nuclear Information System (INIS)

    Koo, Gyeong-Hoi; Kwon, Jong-Jooh; Kim, Wanjae

    2009-01-01

    In this paper, a method to consider temperature dependent material properties when using the Green's function method is proposed by using a numerical weight function approach. This is verified by using detailed finite element analyses for a pressurizer spray nozzle with various assumed thermal transient load cases. From the results, it is found that the temperature dependent material properties can significantly affect the maximum peak stresses and the proposed method can resolve this problem with the weight function approach. Finally, it is concluded that the temperature dependency of the material properties affects the maximum stress ranges for a fatigue evaluation. Therefore, it is necessary to consider this effect to monitor fatigue damage when using a Green's function method for the real operating conditions in a nuclear power plant

  8. Stable Isotopic Variations in Precipitation in Southwest China

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    This study analyzes the relationships of stable isotopes in precipitation with temperature, air pressure and humidity at different altitudes, and the potential influencing mechanisms of control factors on the stable isotopes in precipitation in Southwest China. There appear marked negative correlations of the δ18O in precipitation with precipitation amount, vapor pressure and atmospheric precipitable water (PW)at the Mengzi, Simao and Tengchong stations on the synoptic timescale; the marked negative correlations between the δ18O in precipitation and the diurnal mean temperature at 400 hPa, 500 hPa, 700 hPa and 850hPa are different from the temperature effect in middle-high-latitude inland areas. In addition, the notable positive correlation between the δ18O in precipitation and the dew-point deficit △Td at different altitudes is found at the three stations. Precipitation is not the only factor generating an amount effect. Probably,the amount effect is related to the variations of atmospheric circulation and vapor origins. On the annual timescale, the annual precipitation amount weighted-mean δ18O displays negative correlations not only with annual precipitation but also with annual mean temperature at 500 hPa. It can be deduced that, in the years with an abnormally strong summer monsoon, more warm and wet air from low-latitude oceans is transported northward along the vapor channel located in Southwest China and generates abnormally strong rainfall on the way. Meanwhile, the abnormally strong condensation process will release more condensed latent heat in the atmosphere, and this will lead to a rise of atmospheric temperature during rainfall but a decline of δ18O in the precipitation. On the other hand, in the years with an abnormally weak summer monsoon, the precipitation and the atmospheric temperature during rainfalls decrease abnormally but the δ18O in precipitation increases.

  9. Online dynamical downscaling of temperature and precipitation within the iLOVECLIM model (version 1.1)

    Science.gov (United States)

    Quiquet, Aurélien; Roche, Didier M.; Dumas, Christophe; Paillard, Didier

    2018-02-01

    This paper presents the inclusion of an online dynamical downscaling of temperature and precipitation within the model of intermediate complexity iLOVECLIM v1.1. We describe the following methodology to generate temperature and precipitation fields on a 40 km × 40 km Cartesian grid of the Northern Hemisphere from the T21 native atmospheric model grid. Our scheme is not grid specific and conserves energy and moisture in the same way as the original climate model. We show that we are able to generate a high-resolution field which presents a spatial variability in better agreement with the observations compared to the standard model. Although the large-scale model biases are not corrected, for selected model parameters, the downscaling can induce a better overall performance compared to the standard version on both the high-resolution grid and on the native grid. Foreseen applications of this new model feature include the improvement of ice sheet model coupling and high-resolution land surface models.

  10. Temperature and precipitation fluctuations in the Czech Republic during the period of instrumental measurements

    Czech Academy of Sciences Publication Activity Database

    Brázdil, Rudolf; Zahradníček, Pavel; Pisoft, P.; Štěpánek, Petr; Bělinová, M.; Dobrovolný, Petr

    2012-01-01

    Roč. 110, 1-2 (2012), s. 17-34 ISSN 0177-798X R&D Projects: GA MŠk(CZ) ED1.1.00/02.0073 Institutional support: RVO:67179843 Keywords : secular station * instrumental period * homogenization * air temperature * precipitation * fluctuation * cyclicity * wavelet analysis * Czech Republic Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 1.759, year: 2012

  11. Evaluation of precipitates used in strainer head loss testing: Part III. Long-term aluminum hydroxide precipitation tests in borated water

    International Nuclear Information System (INIS)

    Bahn, Chi Bum; Kasza, Ken E.; Shack, William J.; Natesan, Ken; Klein, Paul

    2011-01-01

    Research highlights: → Aluminum hydroxide precipitation boundary is similar to that for amorphous phase. → Various precipitation tests are combined into one map in temperature-'pH + p[Al] T '. → Flocculation tendency of precipitates depend on pH and total Al concentration. → DLVO theory explains qualitatively the dependency of flocculation tendency on pH. - Abstract: Long-term aluminum (Al) hydroxide precipitation tests were conducted in slightly alkaline solutions containing 2500 ppm boron. The solution temperature was cycled to obtain a temperature history more representative of emergency core cooling system temperatures after a loss-of-coolant accident. The observed Al precipitation boundary was close to predicted results for amorphous precipitates, which are higher than the solubility expected for crystalline forms. Bench-scale and loop head loss test results under various conditions were successfully combined into single map in a temperature - 'pH + p[Al] T ' domain, which yielded two bounding lines for Al hydroxide solubility in borated alkaline water that depend on whether or not loop head loss tests with Al alloy coupons are included. Precipitates were observed to form either as fine, cloudy suspensions, which showed very little tendency to settle, or as flocculated precipitates. The flocculation tendency of the precipitates can be qualitatively explained by a colloid stability theory or a phase diagram for protein solutions.

  12. Diagnosing Geospatial Uncertainty Visualization Challenges in Seasonal Temperature and Precipitation Forecasts

    Science.gov (United States)

    Speciale, A.; Kenney, M. A.; Gerst, M.; Baer, A. E.; DeWitt, D.; Gottschalk, J.; Handel, S.

    2017-12-01

    The uncertainty of future weather and climate conditions is important for many decisions made in communities and economic sectors. One tool that decision-makers use in gauging this uncertainty is forecasts, especially maps (or visualizations) of probabilistic forecast results. However, visualizing geospatial uncertainty is challenging because including probability introduces an extra variable to represent and probability is often poorly understood by users. Using focus group and survey methods, this study seeks to understand the barriers to using probabilistic temperature and precipitation visualizations for specific decisions in the agriculture, energy, emergency management, and water resource sectors. Preliminary results shown here focus on findings of emergency manager needs. Our experimental design uses National Oceanic and Atmospheric Administration (NOAA's) Climate Prediction Center (CPC) climate outlooks, which produce probabilistic temperature and precipitation forecast visualizations at the 6-10 day, 8-14 day, 3-4 week, and 1 and 3 month timeframes. Users were asked to complete questions related to how they use weather information, how uncertainty is represented, and design elements (e.g., color, contour lines) of the visualizations. Preliminary results from the emergency management sector indicate there is significant confusion on how "normal" weather is defined, boundaries between probability ranges, and meaning of the contour lines. After a complete understandability diagnosis is made using results from all sectors, we will collaborate with CPC to suggest modifications to the climate outlook visualizations. These modifications will then be retested in similar focus groups and web-based surveys to confirm they better meet the needs of users.

  13. Effect of pH and phosphate on calcium carbonate polymorphs precipitated at near-freezing temperature

    NARCIS (Netherlands)

    Hu, Yu-Bin; Wolthers, Mariëtte; Wolf-Gladrow, Dieter A.; Nehrke, Gernot

    2015-01-01

    The effects of pH and phosphate on the precipitation of calcium carbonate polymorphs from aqueous solution were investigated. Experiments were carried out at near-freezing temperature and two different pH conditions (pH 13.4 and 9.0). At each pH condition, solutions having different concentrations

  14. Changes in a suite of indicators of extreme temperature and precipitation under 1.5 and 2 degrees warming

    Science.gov (United States)

    Aerenson, Travis; Tebaldi, Claudia; Sanderson, Ben; Lamarque, Jean-François

    2018-03-01

    Following the 2015 Paris agreement, the Intergovernmental Panel on Climate Change was tasked with assessing climate change impacts and mitigation options for a world that limits warming to 1.5 °C in a special report. To aid the scientific assessment process three low-warming ensembles were generated over the 21st century based on the Paris targets using NCAR-DOE community model, CESM1-CAM5. This study used those simulation results and computed ten extreme climate indices, from definitions created by the Expert Team on Climate Change Detection and Indices, to determine if the three different scenarios cause different intensity and frequency of extreme precipitation or temperature over the 21st century. After computing the indices, statistical tests were used to determine if significant changes affect their characteristics. It was found that at the grid point level significant changes emerge in all scenarios, for nearly all indices. The temperature indices show widespread significant change, while the behavior of precipitation indices reflects the larger role that internal variability plays, even by the end of the century. Nonetheless differences can be assessed, in substantial measure for many of these indices: changes in nearly all indices have a strong correlation to global mean temperature, so that scenarios and times with greater temperature change experience greater index changes for many regions. This is particularly true of the temperature-related indices, but can be assessed for some regions also for the indices related to precipitation intensity. These results thus show that even for scenarios that are separated by only half of a degree in global average temperature, the statistics of extremes are significantly different.

  15. Accumulation of soluble sugars in peel at high temperature leads to stay-green ripe banana fruit.

    Science.gov (United States)

    Yang, Xiaotang; Pang, Xuequn; Xu, Lanying; Fang, Ruiqiu; Huang, Xuemei; Guan, Peijian; Lu, Wangjin; Zhang, Zhaoqi

    2009-01-01

    Bananas (Musa acuminata, AAA group) fail to develop a yellow peel and stay green when ripening at temperatures >24 degrees C. The identification of the mechanisms leading to the development of stay-green ripe bananas has practical value and is helpful in revealing pathways involved in the regulation of chlorophyll (Chl) degradation. In the present study, the Chl degradation pathway was characterized and the progress of ripening and senescence was assessed in banana peel at 30 degrees C versus 20 degrees C, by monitoring relevant gene expression and ripening and senescence parameters. A marked reduction in the expression levels of the genes for Chl b reductase, SGR (Stay-green protein), and pheophorbide a oxygenase was detected for the fruit ripening at 30 degrees C, when compared with fruit at 20 degrees C, indicating that Chl degradation was repressed at 30 degrees C at various steps along the Chl catabolic pathway. The repressed Chl degradation was not due to delayed ripening and senescence, since the fruit at 30 degrees C displayed faster onset of various ripening and senescence symptoms, suggesting that the stay-green ripe bananas are of similar phenotype to type C stay-green mutants. Faster accumulation of high levels of fructose and glucose in the peel at 30 degrees C prompted investigation of the roles of soluble sugars in Chl degradation. In vitro incubation of detached pieces of banana peel showed that the pieces of peel stayed green when incubated with 150 mM glucose or fructose, but turned completely yellow in the absence of sugars or with 150 mM mannitol, at either 20 degrees C or 30 degrees C. The results suggest that accumulation of sugars in the peel induced by a temperature of 30 degrees C may be a major factor regulating Chl degradation independently of fruit senescence.

  16. Relating ring width of Mediterranean evergreen species to seasonal and annual variations of precipitation and temperature

    Science.gov (United States)

    Nijland, W.; Jansma, E.; Addink, E. A.; Domínguez Delmás, M.; de Jong, S. M.

    2011-05-01

    Plant growth in Mediterranean landscapes is limited by the typical summer-dry climate. Forests in these areas are only marginally productive and may be quite susceptible to modern climate change. To improve our understanding of forest sensitivity to annual and seasonal climatic variability, we use tree-ring measurements of two Mediterranean evergreen tree species: Quercus ilex L. and Arbutus unedo L. We sampled 34 stems of these species on three different types of substrates in the Peyne study area in southern France. The resulting chronologies were analysed in combination with 38 yr of monthly precipitation and temperature data to reconstruct the response of stem growth to climatic variability. Results indicate a strong positive response to May and June precipitation, as well as a significant positive influence of early-spring temperatures and a negative growth response to summer heat. Comparison of the data with more detailed productivity measurements in two contrasting years confirms these observations and shows a strong productivity limiting effect of low early-summer precipitation. The results show that tree-ring data from Q.ilex and A.unedo can provide valuable information about the response of these tree species to climate variability, improving our ability to predict the effects of climate change in Mediterranean ecosystems.

  17. Historical and projected trends in temperature and precipitation extremes in Australia in observations and CMIP5

    OpenAIRE

    Alexander, Lisa V.; Arblaster, Julie M.

    2017-01-01

    This study expands previous work on climate extremes in Australia by investigating the simulation of a large number of extremes indices in the CMIP5 multi-model dataset and comparing them to multiple observational datasets over a century of observed data using consistent methods. We calculate 24 indices representing extremes of temperature and precipitation from 1911 to 2010 over Australia and show that there have been significant observed trends in temperature extremes associated with warmin...

  18. Green Leaf Volatile Emissions during High Temperature and Drought Stress in a Central Amazon Rainforest.

    Science.gov (United States)

    Jardine, Kolby J; Chambers, Jeffrey Q; Holm, Jennifer; Jardine, Angela B; Fontes, Clarissa G; Zorzanelli, Raquel F; Meyers, Kimberly T; de Souza, Vinicius Fernadez; Garcia, Sabrina; Gimenez, Bruno O; Piva, Luani R de O; Higuchi, Niro; Artaxo, Paulo; Martin, Scot; Manzi, Antônio O

    2015-09-15

    Prolonged drought stress combined with high leaf temperatures can induce programmed leaf senescence involving lipid peroxidation, and the loss of net carbon assimilation during early stages of tree mortality. Periodic droughts are known to induce widespread tree mortality in the Amazon rainforest, but little is known about the role of lipid peroxidation during drought-induced leaf senescence. In this study, we present observations of green leaf volatile (GLV) emissions during membrane peroxidation processes associated with the combined effects of high leaf temperatures and drought-induced leaf senescence from individual detached leaves and a rainforest ecosystem in the central Amazon. Temperature-dependent leaf emissions of volatile terpenoids were observed during the morning, and together with transpiration and net photosynthesis, showed a post-midday depression. This post-midday depression was associated with a stimulation of C₅ and C₆ GLV emissions, which continued to increase throughout the late afternoon in a temperature-independent fashion. During the 2010 drought in the Amazon Basin, which resulted in widespread tree mortality, green leaf volatile emissions (C₆ GLVs) were observed to build up within the forest canopy atmosphere, likely associated with high leaf temperatures and enhanced drought-induced leaf senescence processes. The results suggest that observations of GLVs in the tropical boundary layer could be used as a chemical sensor of reduced ecosystem productivity associated with drought stress.

  19. Designing Nanoscale Precipitates in Novel Cobalt-based Superalloys to Improve Creep Resistance and Operating Temperature

    Energy Technology Data Exchange (ETDEWEB)

    Dunand, David C. [Northwestern Univ., Evanston, IL (United States); Seidman, David N. [Northwestern Univ., Evanston, IL (United States); Wolverton, Christopher [Northwestern Univ., Evanston, IL (United States); Saal, James E. [Northwestern Univ., Evanston, IL (United States); Bocchini, Peter J. [Northwestern Univ., Evanston, IL (United States); Sauza, Daniel J. [Northwestern Univ., Evanston, IL (United States)

    2014-10-01

    High-temperature structural alloys for aerospace and energy applications have long been dominated by Ni-base superalloys, whose strength and creep resistance can be attributed to microstructures consisting of a large volume fraction of ordered (L12) γ'-precipitates embedded in a disordered’(f.c.c.) γ-matrix. These alloys exhibit excellent mechanical behavior and thermal stability, but after decades of incremental improvement are nearing the theoretical limit of their operating temperatures. Conventional Co-base superalloys are solid-solution or carbide strengthened; although they see industrial use, these alloys are restricted to lower-stress applications because the absence of an ordered intermetallic phase places an upper limit on their mechanical performance. In 2006, a γ+γ' microstructure with ordered precipitates analogous to (L12) Ni3Al was first identified in the Co-Al-W ternary system, allowing, for the first time, the development of Co-base alloys with the potential to meet or even exceed the elevated-temperature performance of their Ni-base counterparts. The potential design space for these alloys is complex: the most advanced Ni-base superalloys may contain as many as 8-10 minor alloying additions, each with a specified purpose such as raising the γ' solvus temperature or improving creep strength. Our work has focused on assessing the effects of alloying additions on microstructure and mechanical behavior of γ'-strengthened Co-base alloys in an effort to lay the foundations for understanding this emerging alloy system. Investigation of the size, morphology, and composition of γ' and other relevant phases is investigated utilizing scanning electron microscopy (SEM) and 3-D picosecond ultraviolet local electrode atom probe tomography (APT). Microhardness, compressive yield stress at ambient and elevated temperatures, and compressive high-temperature creep measurements are employed to

  20. Urban church forests for local temperature regulation: Implications the role of managing and incorporating urban green space in urban planning

    Directory of Open Access Journals (Sweden)

    Tulu Tolla TURA

    2016-11-01

    Full Text Available The global surface temperature shows an increment of 0.50.1C per decade and 1.050.3C per century from 1880-2014 with greater increases in cities than non-urban areas. Global communities are shifting towards urbanization due to various factors. Urbanization has caused lack of stable condition for dwellers due to environmental and anthropogenic factors such as land cover changes. Urban temperature rising is the main factors hindering urban dwellers at global level due to insufficient green areas. Social institutions are playing important role in urban greening and urban climate regulation. Ethiopian Orthodox Tewahido Church has long history in indigenous trees biodiversity conservation that plays largely greening role in urban and rural parts of the country. However, there is a research gap in Ethiopia regarding the role of urban green area in the church yards in regulating urban temperature and microclimate change. Therefore, the study evaluated the role of church managed forests in Addis Ababa in regulating surface temperature. Surface temperature inside four church forests at a buffer radius of 0–50 m, 50–100 m, 100–200 m and 200–500 m estimated using Landsat image thermal band 6 of 1986, 2000 and 2010 and ground measurement by ambient thermometer at 10:00 am, 12:30 am and 3:00 pm local time. The ground measurement was done in order to validate satellite image analysis. Plant species diversity, DBH, H, HC, BH and BA was measured. There were 1167 trees in the four studied churches. The mean temperatures of the studied sites were 22.50.1, 23.250.2, 240.6, 24.61.1 and 25.52.2C on site,0–50 m, 50–100 m, 100–200m and 200–500 m respectively for 1986 images; 23.20.5, 23.31.0, 24.32.1, 24.82.2 and 25.51.8C on site, 0-50 m, 50–100 m, 100–200 m and 200–500 m respectively for 2000 images and 23.20.3, 23.270.2, 23.71.6, 241.4 and 24.71.3C on site, 0–50 m, 50–100 m

  1. Spatial patterns of sea surface temperature influences on East African precipitation as revealed by empirical orthogonal teleconnections

    Directory of Open Access Journals (Sweden)

    Tim eAppelhans

    2016-02-01

    Full Text Available East Africa is characterized by a rather dry annual precipitation climatology with two distinct rainy seasons. In order to investigate sea surface temperature driven precipitation anomalies for the region we use the algorithm of empirical orthogonal teleconnection analysis as a data mining tool. We investigate the entire East African domain as well as 5 smaller sub-regions mainly located in areas of mountainous terrain. In searching for influential sea surface temperature patterns we do not focus any particular season or oceanic region. Furthermore, we investigate different time lags from zero to twelve months. The strongest influence is identified for the immediate (i.e. non-lagged influences of the Indian Ocean in close vicinity to the East African coast. None of the most important modes are located in the tropical Pacific Ocean, though the region is sometimes coupled with the Indian Ocean basin. Furthermore, we identify a region in the southern Indian Ocean around the Kerguelen Plateau which has not yet been reported in the literature with regard to precipitation modulation in East Africa. Finally, it is observed that not all regions in East Africa are equally influenced by the identified patterns.

  2. Precipitate microstructure evolution in exposed IN738LC superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Strunz, Pavel, E-mail: strunz@ujf.cas.cz [Nuclear Physics Institute ASCR, CZ-25068 Řež near Prague (Czech Republic); Petrenec, Martin [Institute of Physics of Materials of the AS CR, Brno (Czech Republic); Gasser, Urs [Laboratory for Neutron Scattering, PSI, CH-5232 Villigen (Switzerland); Tobiáš, Jiří; Polák, Jaroslav [Institute of Physics of Materials of the AS CR, Brno (Czech Republic); Šaroun, Jan [Nuclear Physics Institute ASCR, CZ-25068 Řež near Prague (Czech Republic)

    2014-03-15

    Highlights: • Evolution of γ′-phase morphology in IN738LC Ni-base superalloy was examined by SANS. • In situ tests at high temperatures revealed trimodal precipitate distribution. • Formation, dissolution and (slow) kinetics of small γ′ precipitates was determined. • Equilibrium volume fraction of γ′ phase is significantly higher than 45%. • The small γ′ precipitates arise regardless the application of the mechanical load. -- Abstract: Nickel base superalloy IN738LC has been studied after low-cycle fatigue by Small Angle Neutron Scattering (SANS). Samples subjected to high-temperature low-cycle fatigue were annealed at various temperatures to change the size and the distribution of precipitates. Ex and in situ SANS and TEM studies were performed. It was found that additional precipitates are formed either during slow cooling from high temperatures or after reheating above 570 °C. Their size and distribution were evaluated. The precipitates arise regardless the application of the mechanical load. Nevertheless, these small precipitates influence low-cycle fatigue resistance. From the SANS data, it can be also deduced that the equilibrium volume fraction of γ′-precipitates at temperatures from room temperature to 825 °C is significantly higher than 45%. The kinetics of formation of small and medium-size γ′ precipitates at 700 and 800 °C was determined as well.

  3. Few apparent short-term effects of elevated soil temperature and increased frequency of summer precipitation on the abundance and taxonomic diversity of desert soil micro- and meso-fauna

    Science.gov (United States)

    Darby, B.J.; Neher, D.A.; Housman, D.C.; Belnap, J.

    2011-01-01

    Frequent hydration and drying of soils in arid systems can accelerate desert carbon and nitrogen mobilization due to respiration, microbial death, and release of intracellular solutes. Because desert microinvertebrates can mediate nutrient cycling, and the autotrophic components of crusts are known to be sensitive to rapid desiccation due to elevated temperatures after wetting events, we studied whether altered soil temperature and frequency of summer precipitation can also affect the composition of food web consumer functional groups. We conducted a two-year field study with experimentally-elevated temperature and frequency of summer precipitation in the Colorado Plateau desert, measuring the change in abundance of nematodes, protozoans, and microarthropods. We hypothesized that microfauna would be more adversely affected by the combination of elevated temperature and frequency of summer precipitation than either effect alone, as found previously for phototrophic crust biota. Microfauna experienced normal seasonal fluctuations in abundance, but the effect of elevated temperature and frequency of summer precipitation was statistically non-significant for most microfaunal groups, except amoebae. The seasonal increase in abundance of amoebae was reduced with combined elevated temperature and increased frequency of summer precipitation compared to either treatment alone, but comparable with control (untreated) plots. Based on our findings, we suggest that desert soil microfauna are relatively more tolerant to increases in ambient temperature and frequency of summer precipitation than the autotrophic components of biological soil crust at the surface.

  4. Strength and rupture-life transitions caused by secondary carbide precipitation in HT-9 during high-temperature low-rate mechanical testing

    International Nuclear Information System (INIS)

    DiMelfi, R.J.; Gruber, E.E.; Kramer, J.M.; Hughes, T.H.

    1992-01-01

    The martensitic-ferritic alloy HT-9 is slated for long-term use as a fuel-cladding material in the Integral Fast Reactor. Analysis of published high-temperature mechanical property data suggests that secondary carbide precipitation would occur during service life causing substantial strengthening of the as-heat-treated material. Aspects of the kinetics of this precipitation process are extracted from calculations of the back stress necessary to produce the observed strengthening effect under various creep loading conditions. The resulting Arrhenius factor is shown to agree quantitatively with shifts to higher strength of crept material in reference to the intrinsic strength of HT-9. The results of very low constant strain-rate high-temperature tensile tests on as-heat-treated HT-9 that focus on the transition in strength with precipitation will be presented and related to rupture-life

  5. Rheology of tetraphenylborate precipitate slurry

    International Nuclear Information System (INIS)

    Goren, I.D.; Martin, H.D.; McLain, M.A.

    1985-01-01

    The rheological properties of tetraphenylborate precipitate slurry were determined. This nonradioactive slurry simulates the radioactive tetraphenylborate precipitate generated at the Savannah River Plant by the In-Tank Precipitation Process. The data obtained in this study was applied in the design of slurry pumps, transfer pumps, transfer lines, and vessel agitation for the Defense Waste Processing Facility and other High Level Waste treatment projects. The precipitate slurry behaves as a Bingham plastic. The yield stress is directly proportional to the concentration of insoluble solids over the range of concentrations studied. The consistency is also a linear function of insoluble solids over the same concentration range. Neither the yield stress nor the consistency was observed to be affected by the presence of the soluble solids. Temperature effects on flow properties of the slurry were also examined: the yield stress is inversely proportional to temperature, but the consistency of the slurry is independent of temperature. No significant time-dependent effects were found. 4 refs., 4 figs., 3 tabs

  6. A comparison of growth rate of late Holocene stalagmites with atmospheric precipitation and temperature, and its implications for paleoclimatology

    Science.gov (United States)

    Railsback, L. Bruce

    2018-05-01

    Growth rate of stalagmites can vary with many factors of physical environment, ecology, and karst hydrogeology, to the extent that growth rates calculated from a carefully selected set of data from 80 stalagmites from around the world vary by a factor of 400 from smallest to largest. Growth rates of those 80 stalagmites nonetheless collectively show correlations to atmospheric precipitation and temperature that are non-trivial (r2 = 0.12 and 0.20, respectively) and unlikely to have arisen randomly (p = 0.002 and 0.00002). Those global relationships are also supported by previously published studies of individual drip sites. The general trend of growth rates is not a monotonic increase with precipitation; instead, it reaches a maximum at annual precipitation rates between 700 and 2300 mm/year, which both counters many model predictions that growth rates should increase monotonically with drip rate and complicates use of growth rate as a proxy for past precipitation. The general trend of growth rates among the 80 stalagmites is a monotonic increase with temperature. However, the low values of r2 in both of these general trends indicate that growth rate can be at best a qualitative rather than quantitative proxy of past conditions. Growth rate shows no statistically significant relationship to effective precipitation, seemingly because of the confounding effect of temperature. Growth rates of aragonite-bearing stalagmites are commonly greater than rates in stalagmites in which calcite is the only carbonate mineral, suggesting both the need for careful identification of mineralogy and the special applicability of aragonitic stalagmites in high-resolution studies. Aragonite has exceptionally great frequency in settings with low effective atmospheric precipitation, supporting previous linkages of that mineral to warm dry environments. Closely-spaced sampling used in recent paleoclimatological studies suggests that unexploited long-term low-resolution records of past

  7. Online dynamical downscaling of temperature and precipitation within the iLOVECLIM model (version 1.1

    Directory of Open Access Journals (Sweden)

    A. Quiquet

    2018-02-01

    Full Text Available This paper presents the inclusion of an online dynamical downscaling of temperature and precipitation within the model of intermediate complexity iLOVECLIM v1.1. We describe the following methodology to generate temperature and precipitation fields on a 40 km  ×  40 km Cartesian grid of the Northern Hemisphere from the T21 native atmospheric model grid. Our scheme is not grid specific and conserves energy and moisture in the same way as the original climate model. We show that we are able to generate a high-resolution field which presents a spatial variability in better agreement with the observations compared to the standard model. Although the large-scale model biases are not corrected, for selected model parameters, the downscaling can induce a better overall performance compared to the standard version on both the high-resolution grid and on the native grid. Foreseen applications of this new model feature include the improvement of ice sheet model coupling and high-resolution land surface models.

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

    Science.gov (United States)

    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.

  9. Understanding the Seasonal Greenness Trends and Controls in South Asia Using Satellite Based Observations

    Science.gov (United States)

    Sarmah, S.; Jia, G.; Zhang, A.; Singha, M.

    2017-12-01

    South Asia (SA) is one of the most remarkable regions in changing vegetation greenness along with its major expansion of agricultural activity, especially irrigated farming. However, SA is predicted to be a vulnerable agricultural regions to future climate changes. The influence of monsoon climate on the seasonal trends and anomalies of vegetation greenness are not well understood in the region which can provide valuable information about climate-ecosystem interaction. This study analyzed the spatio-temporal patterns of seasonal vegetation trends and variability using satellite vegetation indices (VI) including AVHRR Normalized Difference Vegetation Index (NDVI) (1982-2013) and MODIS Enhanced Vegetation Index (EVI) (2000-2013) in summer monsoon (SM) (June-Sept) and winter monsoon (WM) (Dec-Apr) seasons among irrigated cropland (IC), rainfed cropland (RC) and natural vegetation (NV). Seasonal VI variations with climatic factors (precipitation and temperature) and LULC changes have been investigated to identify the forcings behind the vegetation trends and variability. We found that major greening occurred in the last three decades due to the increase in IC productivity noticeably in WM, however, recent (2000-2013) greening trends were lower than the previous decades (1982-1999) in both the IC and RC indicating the stresses on them. The browning trends, mainly concentrated in NV areas were prominent during WM and rigorous since 2000, confirmed from the moderate resolution EVI and LULC datasets. Winter time maximal temperature had been increasing tremendously whereas precipitation trend was not significant over SA. Both the climate variability and LULC changes had integrated effects on the vegetation changes in NV areas specifically in hilly regions. However, LULC impact was intensified since 2000, mostly in north east India. This study also revealed a distinct seasonal variation in spatial distribution of correlation between VI's and climate anomalies over SA

  10. GREEN SYNTHESIS OF SILVER AND PALLADIUM NANOPARTICLES AT ROOM TEMPERATURE USING COFFEE AND TEA EXTRACT

    Science.gov (United States)

    An extremely simple green approach that generates bulk quantities of nanocrystals of noble metals such as silver (Ag) and palladium (Pd) using coffee and tea extract at room temperature is described. The single-pot method uses no surfactant, capping agent, and/or template. The ob...

  11. Global observed long-term changes in temperature and precipitation extremes: A review of progress and limitations in IPCC assessments and beyond

    Directory of Open Access Journals (Sweden)

    Lisa V. Alexander

    2016-03-01

    Full Text Available The Intergovernmental Panel on Climate Change (IPCC first attempted a global assessment of long-term changes in temperature and precipitation extremes in its Third Assessment Report in 2001. While data quality and coverage were limited, the report still concluded that heavy precipitation events had increased and that there had been, very likely, a reduction in the frequency of extreme low temperatures and increases in the frequency of extreme high temperatures. That overall assessment had changed little by the time of the IPCC Special Report on Extremes (SREX in 2012 and the IPCC Fifth Assessment Report (AR5 in 2013, but firmer statements could be added and more regional detail was possible. Despite some substantial progress throughout the IPCC Assessments in terms of temperature and precipitation extremes analyses, there remain major gaps particularly regarding data quality and availability, our ability to monitor these events consistently and our ability to apply the complex statistical methods required. Therefore this article focuses on the substantial progress that has taken place in the last decade, in addition to reviewing the new progress since IPCC AR5 while also addressing the challenges that still lie ahead.

  12. H-Phase Precipitation and Martensitic Transformation in Ni-rich Ni-Ti-Hf and Ni-Ti-Zr High-Temperature Shape Memory Alloys

    Science.gov (United States)

    Evirgen, A.; Pons, J.; Karaman, I.; Santamarta, R.; Noebe, R. D.

    2018-03-01

    The distributions of H-phase precipitates in Ni50.3Ti29.7Hf20 and Ni50.3Ti29.7Zr20 alloys formed by aging treatments at 500 and 550 °C or slow furnace cooling and their effects on the thermal martensitic transformation have been investigated by TEM and calorimetry. The comparative study clearly reveals faster precipitate-coarsening kinetics in the NiTiZr alloy than in NiTiHf. For precipitates of a similar size of 10-20 nm in both alloys, the martensite plates in Ni50.3Ti29.7Zr20 have larger widths and span a higher number of precipitates compared with the Ni50.3Ti29.7Hf20 alloy. However, for large H-phase particles with hundreds of nm in length, no significant differences in the martensitic microstructures of both alloy systems have been observed. The martensitic transformation temperatures of Ni50.3Ti29.7Hf20 are 80-90 °C higher than those of Ni50.3Ti29.7Zr20 in the precipitate-free state and in the presence of large particles of hundreds on nm in length, but this difference is reduced to only 10-20 °C in samples with small H-phase precipitates. The changes in the transformation temperatures are consistent with the differences in the precipitate distributions between the two alloy systems observed by TEM.

  13. An assessment of historical Antarctic precipitation and temperature trend using CMIP5 models and reanalysis datasets

    Science.gov (United States)

    Tang, Malcolm S. Y.; Chenoli, Sheeba Nettukandy; Samah, Azizan Abu; Hai, Ooi See

    2018-03-01

    The study of Antarctic precipitation has attracted a lot of attention recently. The reliability of climate models in simulating Antarctic precipitation, however, is still debatable. This work assess the precipitation and surface air temperature (SAT) of Antarctica (90 oS to 60 oS) using 49 Coupled Model Intercomparison Project phase 5 (CMIP5) global climate models and the European Centre for Medium-range Weather Forecasts "Interim" reanalysis (ERA-Interim); the National Centers for Environmental Prediction Climate Forecast System Reanalysis (CFSR); the Japan Meteorological Agency 55-year Reanalysis (JRA-55); and the Modern Era Retrospective-analysis for Research and Applications (MERRA) datasets for 1979-2005 (27 years). For precipitation, the time series show that the MERRA and JRA-55 have significantly increased from 1979 to 2005, while the ERA-Int and CFSR have insignificant changes. The reanalyses also have low correlation with one another (generally less than +0.69). 37 CMIP5 models show increasing trend, 18 of which are significant. The resulting CMIP5 MMM also has a significant increasing trend of 0.29 ± 0.06 mm year-1. For SAT, the reanalyses show insignificant changes and have high correlation with one another, while the CMIP5 MMM shows a significant increasing trend. Nonetheless, the variability of precipitation and SAT of MMM could affect the significance of its trend. One of the many reasons for the large differences of precipitation is the CMIP5 models' resolution.

  14. Application of Eh-pH diagram for room temperature precipitation of zinc stannate microcubes in an aqueous media

    International Nuclear Information System (INIS)

    Al-Hinai, Ashraf T.; Al-Hinai, Muna H.; Dutta, Joydeep

    2014-01-01

    Graphical abstract: - Highlights: • One pot aqueous synthesis of zinc stannate (ZnSnO 3 ) particles at low temperature. • Synthesis designed with the assistance of potential-pH diagram. • ZnSnO 3 estimated to be stable between pH 8 and 12 was used for synthesis of the particles. • ZnSnO 3 ·3H 2 O were formed during the precipitation of zinc stannate. - Abstract: Potential-pH diagram assisted-design for controlled precipitation is an attractive method to obtain engineered binary and ternary oxide particles. Aqueous synthesis conditions of zinc stannate (ZnSnO 3 ) particles at low temperature were formulated with the assistance of potential-pH diagram. The pH of a solution containing stoichiometric amounts of Zn 2+ and Sn 4+ was controlled for the precipitation in a one pot synthesis step at room temperature (25 °C). The effect of the concentration of the reactants on the particle size was studied by varying the concentration of the precursor (Zn 2+ + Sn 4+ ) solution. Scanning electron micrographs show that the particles are monodispersed micron sized cubes formed by the self-organization of nano-sized crystallites. The obtained microcubes characterized by X-ray Diffraction and thermo gravimetric analysis (TGA) show that the particles are in ZnSnO 3 ·3H 2 O form

  15. Relating ring width of Mediterranean evergreen species to seasonal and annual variations of precipitation and temperature

    Directory of Open Access Journals (Sweden)

    W. Nijland

    2011-05-01

    Full Text Available Plant growth in Mediterranean landscapes is limited by the typical summer-dry climate. Forests in these areas are only marginally productive and may be quite susceptible to modern climate change. To improve our understanding of forest sensitivity to annual and seasonal climatic variability, we use tree-ring measurements of two Mediterranean evergreen tree species: Quercus ilex L. and Arbutus unedo L. We sampled 34 stems of these species on three different types of substrates in the Peyne study area in southern France. The resulting chronologies were analysed in combination with 38 yr of monthly precipitation and temperature data to reconstruct the response of stem growth to climatic variability. Results indicate a strong positive response to May and June precipitation, as well as a significant positive influence of early-spring temperatures and a negative growth response to summer heat. Comparison of the data with more detailed productivity measurements in two contrasting years confirms these observations and shows a strong productivity limiting effect of low early-summer precipitation. The results show that tree-ring data from Q.ilex and A.unedo can provide valuable information about the response of these tree species to climate variability, improving our ability to predict the effects of climate change in Mediterranean ecosystems.

  16. Evaluation of CMIP5 Ability to Reproduce 20th Century Regional Trends in Surface Air Temperature and Precipitation over CONUS

    Science.gov (United States)

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

    2017-12-01

    Monitoring temporal changes in key climate variables, such as surface air temperature and precipitation, is an integral part of the ongoing efforts of the United States National Climate Assessment (NCA). Climate models participating in CMIP5 provide future trends for four different emissions scenarios. In order to have confidence in the future projections of surface air temperature and precipitation, it is crucial to evaluate the ability of CMIP5 models to reproduce observed trends for three different time periods (1895-1939, 1940-1979, and 1980-2005). Towards this goal, trends in surface air temperature and precipitation obtained from the NOAA nClimGrid 5 km gridded station observation-based product are compared during all three time periods to the 206 CMIP5 historical simulations from 48 unique GCMs and their multi-model ensemble (MME) for NCA-defined climate regions during summer (JJA) and winter (DJF). This evaluation quantitatively examines the biases of simulated trends of the spatially averaged temperature and precipitation in the NCA climate regions. The CMIP5 MME reproduces historical surface air temperature trends for JJA for all time period and all regions, except the Northern Great Plains from 1895-1939 and Southeast during 1980-2005. Likewise, for DJF, the MME reproduces historical surface air temperature trends across all time periods over all regions except the Southeast from 1895-1939 and the Midwest during 1940-1979. The Regional Climate Model Evaluation System (RCMES), an analysis tool which supports the NCA by providing access to data and tools for regional climate model validation, facilitates the comparisons between the models and observation. The RCMES Toolkit is designed to assist in the analysis of climate variables and the procedure of the evaluation of climate projection models to support the decision-making processes. This tool is used in conjunction with the above analysis and results will be presented to demonstrate its capability to

  17. Documentation of a daily mean stream temperature module—An enhancement to the Precipitation-Runoff Modeling System

    Science.gov (United States)

    Sanders, Michael J.; Markstrom, Steven L.; Regan, R. Steven; Atkinson, R. Dwight

    2017-09-15

    A module for simulation of daily mean water temperature in a network of stream segments has been developed as an enhancement to the U.S. Geological Survey Precipitation Runoff Modeling System (PRMS). This new module is based on the U.S. Fish and Wildlife Service Stream Network Temperature model, a mechanistic, one-dimensional heat transport model. The new module is integrated in PRMS. Stream-water temperature simulation is activated by selection of the appropriate input flags in the PRMS Control File and by providing the necessary additional inputs in standard PRMS input files.This report includes a comprehensive discussion of the methods relevant to the stream temperature calculations and detailed instructions for model input preparation.

  18. Formation and Dissolution of gamma ' Precipitates in IN792 Superalloy at Elevated Temperatures

    Czech Academy of Sciences Publication Activity Database

    Strunz, Pavel; Petrenec, Martin; Polák, Jaroslav; Gasser, U.; Farkas, G.

    2016-01-01

    Roč. 6, č. 2 (2016), č. článku 37. ISSN 2075-4701 R&D Projects: GA ČR GB14-36566G; GA MŠk(CZ) LM2011019 EU Projects: European Commission(XE) 283883 - NMI3-II Institutional support: RVO:61389005 ; RVO:68081723 Keywords : metals * high temperature alloys * superalloy * precipitation * neutron scattering * in-situ neutron diffraction * small-angle neutron scattering Subject RIV: BM - Solid Matter Physics ; Magnetism; JL - Materials Fatigue, Friction Mechanics (UFM-A) Impact factor: 1.984, year: 2016

  19. Effect of creep-aging on precipitates of 7075 aluminum alloy

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Y.C., E-mail: yclin@csu.edu.cn [School of Mechanical and Electrical Engineering, Central South University, Changsha 410083 (China); State Key Laboratory of High Performance Complex Manufacturing, Changsha 410083 (China); State Key Laboratory of Material Processing and Die and Mould Technology, Wuhan 430074 (China); Jiang, Yu-Qiang; Chen, Xiao-Min; Wen, Dong-Xu [School of Mechanical and Electrical Engineering, Central South University, Changsha 410083 (China); State Key Laboratory of High Performance Complex Manufacturing, Changsha 410083 (China); Zhou, Hua-Min [State Key Laboratory of Material Processing and Die and Mould Technology, Wuhan 430074 (China)

    2013-12-20

    The creep-aging behaviors of 7075 aluminum alloy are studied by uniaxial tensile creep experiments under elevated temperatures. The effects of creep-aging temperature and applied stress on the precipitates of 7075-T651 aluminum alloy are investigated using a scanning electron microscope (SEM) and a transmission electron microscope (TEM). Results show that (1) coarse insoluble precipitates (Al{sub 7}Cu{sub 2}Fe and Mg{sub 2}Si) and intermediate precipitates (Al{sub 18}Mg{sub 3}Cr{sub 2} and Al{sub 3}Zr) are found in the aluminum matrix, and the effects of creep-aging treatment on these precipitates are not obvious; (2) the main aging precipitates are η′ and η phases, and the amount of aging precipitates increase with the increase of creep-aging temperature and applied stress; (3) with the increase of creep-aging temperature and applied stress, the precipitates are discontinuously distributed on the grain boundary, and the width of precipitate free zone increases with the increase of creep-aging temperature and applied stress and (4) compared with the microstructure in the traditional stress-free aged sample, the creep-aging process can refine the precipitates and narrow the width of the precipitate free zone.

  20. Local impact of temperature and precipitation on West Nile virus infection in Culex species mosquitoes in northeast Illinois, USA

    Directory of Open Access Journals (Sweden)

    Haramis Linn

    2010-03-01

    Full Text Available Abstract Background Models of the effects of environmental factors on West Nile virus disease risk have yielded conflicting outcomes. The role of precipitation has been especially difficult to discern from existing studies, due in part to habitat and behavior characteristics of specific vector species and because of differences in the temporal and spatial scales of the published studies. We used spatial and statistical modeling techniques to analyze and forecast fine scale spatial (2000 m grid and temporal (weekly patterns of West Nile virus mosquito infection relative to changing weather conditions in the urban landscape of the greater Chicago, Illinois, region for the years from 2004 to 2008. Results Increased air temperature was the strongest temporal predictor of increased infection in Culex pipiens and Culex restuans mosquitoes, with cumulative high temperature differences being a key factor distinguishing years with higher mosquito infection and higher human illness rates from those with lower rates. Drier conditions in the spring followed by wetter conditions just prior to an increase in infection were factors in some but not all years. Overall, 80% of the weekly variation in mosquito infection was explained by prior weather conditions. Spatially, lower precipitation was the most important variable predicting stronger mosquito infection; precipitation and temperature alone could explain the pattern of spatial variability better than could other environmental variables (79% explained in the best model. Variables related to impervious surfaces and elevation differences were of modest importance in the spatial model. Conclusion Finely grained temporal and spatial patterns of precipitation and air temperature have a consistent and significant impact on the timing and location of increased mosquito infection in the northeastern Illinois study area. The use of local weather data at multiple monitoring locations and the integration of mosquito

  1. High Nitrogen Austenitic Stainless Steel Precipitation During Isothermal Annealing

    OpenAIRE

    Maria Domankova; Katarína Bártová; Ivan Slatkovský; Peter Pinke

    2016-01-01

    The time-temperature-precipitation in high-nitrogen austenitic stainless steel was investigated using light optical microscopy, transmission electron microscopy, selected area diffraction and energy-dispersive X-ray spectroscopy. The isothermal precipitation kinetics curves and the corresponding precipitation activation energy were obtained. The diffusion activation energy of M2N precipitation is 129 kJ/mol. The results show that critical temperature for M2N precipitation is about 825°C with ...

  2. Two-stage precipitation of neptunium (IV) oxalate

    International Nuclear Information System (INIS)

    Luerkens, D.W.

    1983-07-01

    Neptunium (IV) oxalate was precipitated using a two-stage precipitation system. A series of precipitation experiments was used to identify the significant process variables affecting precipitate characteristics. Process variables tested were input concentrations, solubility conditions in the first stage precipitator, precipitation temperatures, and residence time in the first stage precipitator. A procedure has been demonstrated that produces neptunium (IV) oxalate particles that filter well and readily calcine to the oxide

  3. Study of asphaltene precipitation by Calorimetry

    DEFF Research Database (Denmark)

    Verdier, Sylvain Charles Roland; Plantier, Frédéric; Bessières, David

    2007-01-01

    Can calorimetry bring new input to the Current understanding of asphaltene precipitation? In this work, two types of precipitation were studied by means of calorimetry: addition of n-heptane into asphaltene solutions and temperature/pressure variations on a recombined live oil. The first series...... of experiments showed that weak forces determine precipitation. Indeed, isothermal titration calorimetry could not detect any clear signal although this technique can detect low-energy transitions such as liquid-liquid equilibrium and rnicellization. The second series of tests proved that precipitation caused...... by T and P variations is exothermic for this system. Furthermore, the temperature-induced precipitation is accompanied by an increase in the apparent thermal expansivity. Therefore, it seems that these two phase transitions exhibit different calorimetric behaviours and they may not be as similar...

  4. Formation of copper precipitates in silicon

    Science.gov (United States)

    Flink, Christoph; Feick, Henning; McHugo, Scott A.; Mohammed, Amna; Seifert, Winfried; Hieslmair, Henry; Heiser, Thomas; Istratov, Andrei A.; Weber, Eicke R.

    1999-12-01

    The formation of copper precipitates in silicon was studied after high-temperature intentional contamination of p- and n-type FZ and Cz-grown silicon and quench to room temperature. With the Transient Ion Drift (TID) technique on p-type silicon a critical Fermi level position at EC-0.2 eV was found. Only if the Fermi level position, which is determined by the concentrations of the acceptors and the copper donors, surpasses this critical value precipitation takes place. If the Fermi level is below this level the supersaturated interstitial copper diffuses out. An electrostatic precipitation model is introduced that correlates the observed precipitation behavior with the electrical activity of the copper precipitates as detected with Deep Level Transient Spectroscopy (DLTS) on n-type and with Minority Carrier Transient Spectroscopy (MCTS) on p-type silicon.

  5. Oxygen-18 in present-day precipitation on the Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    章新平; 姚檀栋; 中尾正义

    2001-01-01

    The temporal and spatial variations of the δ18O in precipitation on the Tibetan Plateau are analyzed. There is no temperature effect in the southern Tibetan Plateau. Amount effect has been observed at Lhasa station. However, the seasonal variations of the δ18O in precipitation are different from that of precipitation intensity, showing that the precipitation intensity is not a main controlling factor on the stable isotopic compositions in precipitation in the southern Tibetan Plateau. There is notable temperature effect in the middle and northern Tibetan Plateau. The seasonal variations of the δ18O in precipitation are almost consistent with those of air temperature there, indicating that temperature is a main factor controlling the stable isotopic variations in precipitation. A meridional cross-section shows that a notable depletion of the stable isotopic ratio in precipitation takes place in the Himalayas due to very strong rainout of vapor as it rises over the Himalayas, then the δ18O remains basi

  6. Characterization of γ- Al{sub 2}O{sub 3} nanopowders synthesized by Co-precipitation method

    Energy Technology Data Exchange (ETDEWEB)

    Jbara, Ahmed S., E-mail: ahmedsbhe@yahoo.com [Center for Sustainable Nanomaterials, Universiti Teknologi Malaysia, Skudai - 81310, Johor Bahru (Malaysia); Physics Department, Science College, Al-Muthanna University, Samawah - 66001 (Iraq); Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, Skudai - 81310, Johor Bahru (Malaysia); Othaman, Zulkafli [Center for Sustainable Nanomaterials, Universiti Teknologi Malaysia, Skudai - 81310, Johor Bahru (Malaysia); Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, Skudai - 81310, Johor Bahru (Malaysia); Ati, Ali A. [Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, Skudai - 81310, Johor Bahru (Malaysia); Saeed, M.A., E-mail: moalsd@gmail.com [Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, Skudai - 81310, Johor Bahru (Malaysia); Division of Science and Technology, University of Education, Township, Lahore - 54770 (Pakistan)

    2017-02-15

    Co-precipitation technique has been used to synthesize gamma-Al{sub 2}O{sub 3} (γ-Al{sub 2}O{sub 3}) nanopowders under annealing temperature effect. The crystalline phase and purity for the prepared powder were characterized by different spectroscopy techniques. XRD analysis confirms the gamma phase of alumina nanopowders with particle diameter ranging from 6 to 24 nm, which confirms the quantum dots formation, which is also supported by the BET measurement. The surface area of the prepared nanopowders is in the range of 109–367 m{sup 2}/g. Morphology analysis indicates that γ-Al{sub 2}O{sub 3} nanopowders are consisted of grains almost spherical in shape. Some agglomeration of nanoparticles occurs, which become more regular hexagonal shaped with the increasing annealing temperature. The small nanoparticles size and the high surface area from a simple procedure for preparing γ-Al{sub 2}O{sub 3} may make it more suitable for use as an adsorbent for malachite green. - Highlights: • Co-precipitation technique is used to synthesize gamma- Al{sub 2}O{sub 3} nanopowders. • Pure gamma- Al{sub 2}O{sub 3} phase was obtained having maximum nanoparticle size is 24 nm. • The quantum dots were formed inside powder. • High surface area of nanopowders at the low annealing temperature. • Increasing annealing temperature causes the hexagonal agglomeration shape.

  7. Observational Quantification of Climatic and Human Influences on Vegetation Greening in China

    Directory of Open Access Journals (Sweden)

    Wenjian Hua

    2017-04-01

    Full Text Available This study attempts to quantify the relative contributions of vegetation greening in China due to climatic and human influences from multiple observational datasets. Satellite measured vegetation greenness, Normalized Difference Vegetation Index (NDVI, and relevant climate, land cover, and socioeconomic data since 1982 are analyzed using a multiple linear regression (MLR method. A statistically significant positive trend of average growing-season (April–October NDVI is found over more than 34% of the vegetated areas, mainly in North China, while significant decreases in NDVI are only seen in less than 5% of the areas. The relationships between vegetation and climate (temperature, precipitation, and radiation vary by geographical location and vegetation type. We estimate the NDVI changes in association with the non-climatic effects by removing the climatic effects from the original NDVI time series using the MLR analysis. Our results indicate that land use change is the dominant factor driving the long-term changes in vegetation greenness. The significant greening in North China is due to the increase in crops, grasslands, and forests. The socioeconomic datasets provide consistent and supportive results for the non-climatic effects at the provincial level that afforestation and reduced fire events generally have a major contribution. This study provides a basis for quantifying the non-climatic effects due to possible human influences on the vegetation greening in China.

  8. Variation of Temperature and Precipitation in Urban Agglomeration and Prevention Suggestion of Waterlogging in Middle and Lower Reaches of Yangtze River

    Science.gov (United States)

    Na, Liu; Youjie, Jin; Jiaqi, Dai

    2018-03-01

    The variation trend of temperature and precipitation during flood season in the middle and lower reaches of the Yangtze River basin in recent 50 years and change characteristics of rainfall in five typical flood prone cities are analysed. Aiming at waterlogging problems in the urban agglomeration of middle and lower reaches of the Yangtze River, the comprehensive prevention and control suggestions are put forward. The results showed that: the temperature trend in the basin decreased and then increased, and the precipitation showed a downward-rising-downward trend, no mutation occurred; The incidence of heavy rainfall events in the five typical cities with daily rainfall more than 50mm showed an upward trend, and increased significantly after 2002. The intensity of precipitation increased gradually. Climate change makes urban agglomeration waterlogging disasters become increasingly prominent in the middle and lower reaches of the Yangtze River.

  9. Going Green and Cold: Biosurfactants from Low-Temperature Environments to Biotechnology Applications.

    Science.gov (United States)

    Perfumo, Amedea; Banat, Ibrahim M; Marchant, Roger

    2018-03-01

    Approximately 80% of the Earth's biosphere is cold, at an average temperature of 5°C, and is populated by a diversity of microorganisms that are a precious source of molecules with high biotechnological potential. Biosurfactants from cold-adapted organisms can interact with multiple physical phases - water, ice, hydrophobic compounds, and gases - at low and freezing temperatures and be used in sustainable (green) and low-energy-impact (cold) products and processes. We review the biodiversity of microbial biosurfactants produced in cold habitats and provide a perspective on the most promising future applications in environmental and industrial technologies. Finally, we encourage exploring the cryosphere for novel types of biosurfactants via both culture screening and functional metagenomics. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Precipitation in solid solution and structural transformations in single crystals of high rhenium ruthenium-containing nickel superalloys at high-temperature creep

    Energy Technology Data Exchange (ETDEWEB)

    Alekseev, A.A.; Petrushin, N.V.; Zaitsev, D.V.; Treninkov, I.A.; Filonova, E.V. [All-Russian Scientific Research Institute of Aviation Materials (VIAM), Moscow (Russian Federation)

    2010-07-01

    The phase composition and structure of single crystals of two superalloys (alloy 1 and alloy 2) were investigated in this work. For alloy 1 (Re - 9 wt%) the kinetics of precipitation in solid solution at heat treatment (HT) was investigated. TEM and X-Ray examinations have revealed that during HT rhombic phase (R-phase) precipitation (Immm class (BCR)) occurs. The TTT diagram is plotted, it contains the time-temperature area of the existence of R-phase particles. The element content of R-phase is identified (at. %): Re- 51.5; Co- 23.5; Cr- 14.8; Mo- 4.2; W- 3.3; Ta- 2.7. For alloy 2 (Re - 6.5 wt %, Ru - 4 wt %) structural transformations at high-temperature creep are investigated. By dark-field TEM methods it is established, that in alloy 2 the additional phase with a rhombic lattice is formed during creep. Particles of this phase precipitate in {gamma}-phase and their quantity increases during high-temperature creep. It is revealed that during creep 3-D dislocation network is formed in {gamma}-phase. At the third stage of creep the process of inversion structure formation is observed in the alloy, i.e. {gamma}'-phase becomes a matrix. Thus during modeling creep the volume fraction of {gamma}'-phase in the samples increases from 30% (at creep duration of 200 hrs) up to 55% (at 500 hrs). The processes of structure formation in Re and Ru-containing nickel superalloys are strongly affected by decomposition of solid solution during high-temperature creep that includes precipitation of additional TCP-phases. (orig.)

  11. High Temperature Deformation Mechanism in Hierarchical and Single Precipitate Strengthened Ferritic Alloys by In Situ Neutron Diffraction Studies.

    Science.gov (United States)

    Song, Gian; Sun, Zhiqian; Li, Lin; Clausen, Bjørn; Zhang, Shu Yan; Gao, Yanfei; Liaw, Peter K

    2017-04-07

    The ferritic Fe-Cr-Ni-Al-Ti alloys strengthened by hierarchical-Ni 2 TiAl/NiAl or single-Ni 2 TiAl precipitates have been developed and received great attentions due to their superior creep resistance, as compared to conventional ferritic steels. Although the significant improvement of the creep resistance is achieved in the hierarchical-precipitate-strengthened ferritic alloy, the in-depth understanding of its high-temperature deformation mechanisms is essential to further optimize the microstructure and mechanical properties, and advance the development of the creep resistant materials. In the present study, in-situ neutron diffraction has been used to investigate the evolution of elastic strain of constitutive phases and their interactions, such as load-transfer/load-relaxation behavior between the precipitate and matrix, during tensile deformation and stress relaxation at 973 K, which provide the key features in understanding the governing deformation mechanisms. Crystal-plasticity finite-element simulations were employed to qualitatively compare the experimental evolution of the elastic strain during tensile deformation at 973 K. It was found that the coherent elastic strain field in the matrix, created by the lattice misfit between the matrix and precipitate phases for the hierarchical-precipitate-strengthened ferritic alloy, is effective in reducing the diffusional relaxation along the interface between the precipitate and matrix phases, which leads to the strong load-transfer capability from the matrix to precipitate.

  12. The influence of weather conditions on road safety : an assessment of the effect of precipitation and temperature.

    NARCIS (Netherlands)

    Bijleveld, F.D. & Churchill, T.

    2009-01-01

    The influence of changes in extreme weather conditions is often identified as a cause of fluctuations in road safety and the resulting numbers of crashes and casualties. This report focuses on an analysis of the aggregate, accumulated effect of weather conditions (precipitation and temperature) on

  13. Temperature and precipitation records from stalagmites grown under disequilibrium conditions: A model approach.

    Science.gov (United States)

    Mühlinghaus, C.; Scholz, D.; Mangini, A.

    2009-04-01

    To reconstruct past variations in Earth's climate, a variety of climate archives are studied. During the last decades stalagmites came into focus due to their long, continuous growth and absolute dating techniques. In this study a numerical model was developed, which calculates variations in temperature and precipitation during the growth period of stalagmites grown under isotopic disequilibrium conditions using the isotope profiles both along the growth axis and individual growth layers as well as the growth depth relation. The model is based on the inversion and combination of existing models (Dreybrodt 1999, Kaufmann et al. 2004, Mühlinghaus et al. 2007, Scholz et al. 2008, Mühlinghaus et al. 2008b) and incorporates important parameters describing the cave and the overlying soil. Beside the dependence on temperature and water supply it depends on the isotopic composition of the drip water, the pCO2 pressure of the soil and the cave atmosphere as well as on the mixing coefficient, which describes mixing between the impinging drop and the existing solution layer. To determine the characteristics of temperature and precipitation, in a first step all other parameters are assumed to remain constant over the whole growth period to simplify calculations. This allows to run the model with only two input variables: the isotopic composition ^13C of the drip water and a temperature information at any point of time during the growth period of the stalagmite (e.g. the recent cave temperature). All other parameters are determined by the model. The CSM (Combined Stalagmite Model, Mühlinghaus et al. 2008a) was applied to three stalagmites from the Marcelo Arévalo cave in Southern Patagonia, Chile (Schimpf 2005, Kilian et al. 2006, Schimpf et al. in prep). These stalagmites grew in a small cave next to each other during the last 4500 years. However, their isotopic profiles along the growth axis show different kinetic influences. Despite these conditions, the temperature

  14. Synthesis of zirconium dioxide by ultrasound assisted precipitation: effect of calcination temperature.

    Science.gov (United States)

    Prasad, Krishnamurthy; Pinjari, D V; Pandit, A B; Mhaske, S T

    2011-09-01

    Nanostructured zirconium dioxide was synthesized from zirconyl nitrate using both conventional and ultrasound assisted precipitation in alkaline medium. The synthesized samples were calcinated at temperatures ranging from 400°C to 900°C in steps of 100°C. The ZrO(2) specimens were characterized using X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The thermal characteristics of the samples were studied via Differential Scanning Calorimetry-Thermo-Gravimetry Analysis (DSC-TGA). The influence of the calcination temperature on the phase transformation process from monoclinic to tetragonal to cubic zirconia and its consequent effect on the crystallite size and % crystallinity of the synthesized ZrO(2) was studied and interpreted. It was observed that the ultrasound assisted technique helped to hasten to the phase transformation and also at some point resulted in phase stabilization of the synthesized zirconia. Copyright © 2011 Elsevier B.V. All rights reserved.

  15. Comparison of the Spatiotemporal Variability of Temperature, Precipitation, and Maximum Daily Spring Flows in Two Watersheds in Quebec Characterized by Different Land Use

    Directory of Open Access Journals (Sweden)

    Ali A. Assani

    2016-01-01

    Full Text Available We compared the spatiotemporal variability of temperatures and precipitation with that of the magnitude and timing of maximum daily spring flows in the geographically adjacent L’Assomption River (agricultural and Matawin River (forested watersheds during the period from 1932 to 2013. With regard to spatial variability, fall, winter, and spring temperatures as well as total precipitation are higher in the agricultural watershed than in the forested one. The magnitude of maximum daily spring flows is also higher in the first watershed as compared with the second, owing to substantial runoff, given that the amount of snow that gives rise to these flows is not significantly different in the two watersheds. These flows occur early in the season in the agricultural watershed because of the relatively high temperatures. With regard to temporal variability, minimum temperatures increased over time in both watersheds. Maximum temperatures in the fall only increased in the agricultural watershed. The amount of spring rain increased over time in both watersheds, whereas total precipitation increased significantly in the agricultural watershed only. However, the amount of snow decreased in the forested watershed. The magnitude of maximum daily spring flows increased over time in the forested watershed.

  16. Influence of Microstructure and Process Conditions on Simultaneous Low-Temperature Surface Hardening and Bulk Precipitation Hardening of Nanoflex®

    DEFF Research Database (Denmark)

    Bottoli, Federico; Winther, Grethe; Christiansen, Thomas L.

    2015-01-01

    Precipitation hardening martensitic stainless steel Nanoflex was low-temperature nitrided or nitrocarburized. In these treatments, simultaneous hardening of the bulk, by precipitation hardening, and the surface by dissolving nitrogen/carbon can be obtained because the treatment temperatures...... and times for these essentially different hardening mechanisms are compatible. The effect of the processing history of the steel on the nitrided/nitrocarburized case was investigated by varying the amounts of austenite and martensite through variation of the degree of plastic deformation by tensile strain...... consisting of martensite results in the deepest nitrided case, while a shallow case develops on a microstructure consisting of austenite. For an initial microstructure consisting of both martensite and austenite a non-uniform case depth is achieved. Simultaneous bulk and surface hardening is only possible...

  17. Carbon exchanges and their responses to temperature and precipitation in forest ecosystems in Yunnan, Southwest China.

    Science.gov (United States)

    Fei, Xuehai; Song, Qinghai; Zhang, Yiping; Liu, Yuntong; Sha, Liqing; Yu, Guirui; Zhang, Leiming; Duan, Changqun; Deng, Yun; Wu, Chuansheng; Lu, Zhiyun; Luo, Kang; Chen, Aiguo; Xu, Kun; Liu, Weiwei; Huang, Hua; Jin, Yanqiang; Zhou, Ruiwu; Li, Jing; Lin, Youxing; Zhou, Liguo; Fu, Yane; Bai, Xiaolong; Tang, Xianhui; Gao, Jinbo; Zhou, Wenjun; Grace, John

    2018-03-01

    Forest ecosystems play an increasingly important role in the global carbon cycle. However, knowledge on carbon exchanges, their spatio-temporal patterns, and the extent of the key controls that affect carbon fluxes is lacking. In this study, we employed 29-site-years of eddy covariance data to observe the state, spatio-temporal variations and climate sensitivity of carbon fluxes (gross primary productivity (GPP), ecosystem respiration (R eco ), and net ecosystem carbon exchange (NEE)) in four representative forest ecosystems in Yunnan. We found that 1) all four forest ecosystems were carbon sinks (the average NEE was -3.40tCha -1 yr -1 ); 2) contrasting seasonality of the NEE among the ecosystems with a carbon sink mainly during the wet season in the Yuanjiang savanna ecosystem (YJ) but during the dry season in the Xishuangbanna tropical rainforest ecosystem (XSBN), besides an equivalent NEE uptake was observed during the wet/dry season in the Ailaoshan subtropical evergreen broad-leaved forest ecosystem (ALS) and Lijiang subalpine coniferous forest ecosystem (LJ); 3) as the GPP increased, the net ecosystem production (NEP) first increased and then decreased when the GPP>17.5tCha -1 yr -1 ; 4) the precipitation determines the carbon sinks in the savanna ecosystem (e.g., YJ), while temperature did so in the tropical forest ecosystem (e.g., XSBN); 5) overall, under the circumstances of warming and decreased precipitation, the carbon sink might decrease in the YJ but maybe increase in the ALS and LJ, while future strength of the sink in the XSBN is somewhat uncertain. However, based on the redundancy analysis, the temperature and precipitation combined together explained 39.7%, 32.2%, 25.3%, and 29.6% of the variations in the NEE in the YJ, XSBN, ALS and LJ, respectively, which indicates that considerable changes in the NEE could not be explained by variations in the temperature and precipitation. Therefore, the effects of other factors (e.g., CO 2 concentration, N

  18. Precipitation of plutonium oxalate from homogeneous solutions

    International Nuclear Information System (INIS)

    Rao, V.K.; Pius, I.C.; Subbarao, M.; Chinnusamy, A.; Natarajan, P.R.

    1986-01-01

    A method for the precipitation of plutonium(IV) oxalate from homogeneous solutions using diethyl oxalate is reported. The precipitate obtained is crystalline and easily filterable with yields in the range of 92-98% for precipitations involving a few mg to g quantities of plutonium. Decontamination factors for common impurities such as U(VI), Am(III) and Fe(III) were determined. TGA and chemical analysis of the compound indicate its composition as Pu(Csub(2)Osub(4))sub(2).6Hsub(2)O. Data are obtained on the solubility of the oxalate in nitric acid and in mixtures of nitric acid and oxalic acid of varying concentrations. Green PuOsub(2) obtained by calcination of the oxalate has specifications within the recommended values for trace foreign substances such as chlorine, fluorine, carbon and nitrogen. (author)

  19. High Nitrogen Austenitic Stainless Steel Precipitation During Isothermal Annealing

    Directory of Open Access Journals (Sweden)

    Maria Domankova

    2016-07-01

    Full Text Available The time-temperature-precipitation in high-nitrogen austenitic stainless steel was investigated using light optical microscopy, transmission electron microscopy, selected area diffraction and energy-dispersive X-ray spectroscopy. The isothermal precipitation kinetics curves and the corresponding precipitation activation energy were obtained. The diffusion activation energy of M2N precipitation is 129 kJ/mol. The results show that critical temperature for M2N precipitation is about 825°C with the corresponding incubation period 2.5 min.

  20. Reproducibility of precipitation distributions over extratropical continental regions in the CMIP5

    Science.gov (United States)

    Hirota, Nagio; Takayabu, Yukari

    2013-04-01

    Reproducibility of precipitation distributions over extratropical continental regions in the CMIP5 Nagio Hirota1,2 and Yukari N. Takayabu2 (1) National Institute of Polar Research (NIPR) (2) Atmosphere and Ocean Research Institute (AORI), the University of Tokyo Reproducibility of precipitation distributions over extratropical continental regions by CMIP5 climate models in their historical runs are evaluated, in comparison with GPCP(V2.2), CMAP(V0911), daily gridded gauge data APHRODITE. Surface temperature, cloud radiative forcing, and atmospheric circulations are also compared with observations of CRU-UEA, CERES, and ERA-interim/ERA40/JRA reanalysis data. It is shown that many CMIP5 models underestimate and overestimate summer precipitation over West and East Eurasia, respectively. These precipitation biases correspond to moisture transport associated with a cyclonic circulation bias over the whole continent of Eurasia. Meanwhile, many models underestimate cloud over the Eurasian continent, and associated shortwave cloud radiative forcing result in a significant warm bias. Evaporation feedback amplify the warm bias over West Eurasia. These processes consistently explain the precipitation biases over the Erasian continent in summer. We also examined reproducibility of winter precipitation, but robust results are not obtained yet due to the large uncertainty in observation associated with the adjustment of snow measurement in windy condition. Better observational data sets are necessary for further model validation. Acknowledgment: This study is supported by the PMM RA of JAXA, Green Network of Excellence (GRENE) Program by the Ministry of Education, Culture, Sports, Science and Technology, Japan, and Environment Research and Technology Development Fund (A-1201) of the Ministry of the Environment, Japan.

  1. Adjusted monthly temperature and precipitation values for Guinea Conakry (1941-2010) using HOMER.

    Science.gov (United States)

    Aguilar, Enric; Aziz Barry, Abdoul; Mestre, Olivier

    2013-04-01

    Africa is a data sparse region and there are very few studies presenting homogenized monthly records. In this work, we introduce a dataset consisting of 12 stations spread over Guinea Conakry containing daily values of maximum and minimum temperature and accumulated rainfall for the period 1941-2010. The daily values have been quality controlled using R-Climdex routines, plus other interactive quality control applications, coded by the authors. After applying the different tests, more than 200 daily values were flagged as doubtful and carefully checked against the statistical distribution of the series and the rest of the dataset. Finally, 40 values were modified or set to missing and the rest were validated. The quality controlled daily dataset was used to produce monthly means and homogenized with HOMER, a new R-pacakge which includes the relative methods that performed better in the experiments conducted in the framework of the COST-HOME action. A total number of 38 inhomogeneities were found for temperature. As a total of 788 years of data were analyzed, the average ratio was one break every 20.7 years. The station with a larger number of inhomogeneities was Conakry (5 breaks) and one station, Kissidougou, was identified as homogeneous. The average number of breaks/station was 3.2. The mean value of the monthly factors applied to maximum (minimum) temperature was 0.17 °C (-1.08 °C) . For precipitation, due to the demand of a denser network to correctly homogenize this variable, only two major inhomogeneities in Conakry (1941-1961, -12%) and Kindia (1941-1976, -10%) were corrected. The adjusted dataset was used to compute regional series for the three variables and trends for the 1941-2010 period. The regional mean has been computed by simply averaging anomalies to 1971-2000 of the 12 time series. Two different versions have been obtained: a first one (A) makes use of the missing values interpolation made by HOMER (so all annual values in the regional series

  2. Radiation induced homogeneous precipitation in undersaturated solid-solutions

    International Nuclear Information System (INIS)

    Cauvin, R.; Martin, G.

    1979-01-01

    A TEM study of 1 MeV electron irradiated Al 1.9 at% Zn solid solution shows that Zn precipitates form, under irradiation at temperatures well above the Zn solvus temperature outside irradiation. The corresponding upward shift of this temperature is dose rate dependent. This new example of radiation-induced precipitation exhibits unexpected features, which are not accounted for by the available models: (1) no correlation exists between the location of the precipitates and that of the point defects sinks; (2) the precipitation of incoherent β-phase with atomic volume smaller than that of the matrix, and of coherent G.P. zones both occurs; (3) the size of the coherent β precipitates saturates at large dose. A general mechanism for solute concentration fluctuations under irradiation is proposed which qualitatively accounts for the formation of coherent G.P. zones and for the nucleation of solute clusters with more complex structures. A reanalysis of Russell's model (1977) for the growth of incoherent precipitates shows that it may qualitatively account for the observed behavior of the β phase precipitates. (Auth.)

  3. Clustering of France Monthly Precipitation, Temperature and Discharge Based on their Multiresolution Links with 500mb Geopotential Height from 1968 to 2008

    Science.gov (United States)

    Massei, N.; Fossa, M.; Dieppois, B.; Vidal, J. P.; Fournier, M.; Laignel, B.

    2017-12-01

    In the context of climate change and ever growing use of water resources, identifying how the climate and watershed signature in discharge variability changes with the geographic location is of prime importance. This study aims at establishing how 1968-2008 multiresolution links between 3 local hydrometerological variables (precipitation, temperature and discharge) and 500 mb geopotential height are structured over France. First, a methodology that allows to encode the 3D geopotential height data into its 1D conformal modulus time series is introduced. Then, for each local variable, their covariations with the geopotential height are computed with cross wavelet analysis. Finally, a clustering analysis of each variable cross spectra is done using bootstrap clustering.We compare the clustering results for each local variable in order to untangle the watershed from the climate drivers in France's rivers discharge. Additionally, we identify the areas in the geopotential height field that are responsible for the spatial structure of each local variable.Main results from this study show that for precipitation and discharge, clear spatial zones emerge. Each cluster is characterized either by different different amplitudes and/or time scales of covariations with geopotential height. Precipitation and discharge clustering differ with the later being simpler which indicates a strong low frequency modulation by the watersheds all over France. Temperature on the other hand shows less clearer spatial zones. For precipitation and discharge, we show that the main action path starts at the northern tropical zone then moves up the to central North Atlantic zone which seems to indicates an interaction between the convective cells variability and the reinforcement of the westerlies jets as one of the main control of the precipitation and discharge over France. Temperature shows a main zone of action directly over France hinting at local temperature/pressure interactions.

  4. Observation of atomic oxygen O(1S) green-line emission in the summer polar upper mesosphere associated with high-energy (≥30 keV) electron precipitation during high-speed solar wind streams

    Science.gov (United States)

    Lee, Young-Sook; Kwak, Young-Sil; Kim, Kyung-Chan; Solheim, Brian; Lee, Regina; Lee, Jaejin

    2017-01-01

    The auroral green-line emission at 557.7 nm wavelength as arising from the atomic oxygen O(1S → 1D) transition typically peaks at an altitude of 100 km specifically in the nightside oval, induced by auroral electrons within an energy range of 100 eV-30 keV. Intense aurora is known as being suppressed by sunlight in summer daytime but usually occurs in low electrical background conductivity. However, in the present study in summer (July) sunlit condition, enhancements of O(1S) emission rates observed by using the Wind Imaging Interferometer/UARS were frequently observed at low altitudes below 90 km, where ice particles are created initially as subvisible and detected as polar mesosphere summer echoes, emerging to be an optical phenomenon of polar mesospheric clouds. The intense O(1S) emission occurring in summer exceeds those occurring in the daytime in other seasons both in occurrence and in intensity, frequently accompanied by occurrences of supersonic neutral velocity (300-1500 m s-1). In the mesosphere, ion motion is controlled by electric field and the momentum is transferred to neutrals. The intense O(1S) emission is well associated with high-energy electron precipitation as observed during an event of high-speed solar wind streams. Meanwhile, since the minimum occurrences of O(1S) emission and supersonic velocity are maintained even in the low precipitation flux, the mechanism responsible is not only related to high-energy electron precipitation but also presumably to the local conditions, including the composition of meteoric-charged ice particles and charge separation expected in extremely low temperatures (<150 K).

  5. Towards better understanding of the response of Sphagnum peatland to increased temperature and reduced precipitation in Central Europe

    Science.gov (United States)

    Juszczak, Radoslaw; Basińska, Anna; Chojnicki, Bogdan; Gąbka, Maciej; Hoffmann, Mathias; Józefczyk, Damian; Lamentowicz, Mariusz; Leśny, Jacek; Łuców, Dominika; Moni, Christophe; Reczuga, Monika; Samson, Mateusz; Silvennoinen, Hanna; Stróżecki, Marcin; Urbaniak, Marek; Zielińska, Małgorzata; Olejnik, Janusz

    2017-04-01

    With respect to climate change peatlands are highly vulnerable ecosystems. Especially a potential drying in future might result in a major carbon source and release to the atmosphere. We carried out a field climate manipulation experiment at Rzecin peatland in western Poland to assess how increased temperature and reduced precipitation may impact carbon balance, vegetation, microbes and water chemistry of the Sphagnum peatland. Here, we present results of measurements conducted in two contrasting years (417 mm and 678 mm of precipitation in very dry 2015 and wet 2016, respectively). The experimental design consists of four treatments, each one replicated three times (control, CO; simulated warming, W; prolonged drought, D and warming & drought, W+D). Increased temperatures (T) during the year were achieved by infrared heaters (400W × 4 per site, approx. 60 Wṡm-2 addition of LW radiation). Precipitation was reduced using an automatic curtain, covering the site during nighttime hours of the growth seasons. The manipulation experiment was successful during both years, increasing the air (30 cm height) and soil temperature (5 cm depth, sites W and D) by up to 0.2 oC and 1.0 oC, respectively. Precipitation was reduced to 37 % during both years. At W+D site the peat temperature was nearly two times higher than on W site indicating the impact of drought on T increase. To study the C exchange we developed an automatic mobile platform for measuring CO2/CH4/H2O fluxes (LGR) as well as 13CO2 and 13CH4 fluxes (PICARRO CRDS G2201-i). Measurements were performed, using dynamic ecosystem chambers (for NEE and Reco) and combined with simultaneous measurements of surface spectral properties. Flux calculation and gap filling was done according to Hoffmann et al. 2015. Methane emissions were significantly higher on manipulated plots than on CO (25 gCṡm-2yr-1) during both years, but only in the very dry 2015, CH4 fluxes were the highest on W+D site (33 gC gCṡm-2yr-1). Besides

  6. Effect of land cover and green space on land surface temperature of a fast growing economic region in Malaysia

    Science.gov (United States)

    Sheikhi, A.; Kanniah, K. D.; Ho, C. H.

    2015-10-01

    Green space must be increased in the development of new cities as green space can moderate temperature in the cities. In this study we estimated the land surface temperature (LST) and established relationships between LST and land cover and various vegetation and urban surface indices in the Iskandar Malaysia (IM) region. IM is one of the emerging economic gateways of Malaysia, and is envisaged to transform into a metropolis by 2025. This change may cause increased temperature in IM and therefore we conducted a study by using Landsat 5 image covering the study region (2,217 km2) to estimate LST, classify different land covers and calculate spectral indices. Results show that urban surface had highest LST (24.49 °C) and the lowest temperature was recorded in, forest, rubber and water bodies ( 20.69 to 21.02°C). Oil palm plantations showed intermediate mean LST values with 21.65 °C. We further investigated the relationship between vegetation and build up densities with temperature. We extracted 1000 collocated pure pixels of Normalized Difference Vegetation Index (NDVI), Normalized Difference Water Index (NDWI), Normalized Difference Built-up Index (NDBI), Urban Index (UI) and LST in the study area. Results show a strong and significant negative correlation with (R2= -0.74 and -0.79) respectively between NDVI, NDWI and LST . Meanwhile a strong positive correlation (R2=0.8 and 0.86) exists between NDBI, UI and LST. These results show the importance of increasing green cover in urban environment to combat any adverse effects of climate change.

  7. Mathematical Modelling of Carbonitride Precipitation during Hot Working in Nb Microalloyed Steels

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Based on thermodynamics and kinetics, precipitation behavior of microalloyed steels was analyzed. Deformation greatly promotes isothermal carbonitride precipitation and makes C-curve shift leftwards. The position and shape of C-curve also depend on the content of Nb and N. C-curve shifts leftwards a little when N content increases and the nose temperature is raised with increasing Nb content. Deformation shortened precipitation start time during continuous cooling, raised precipitation start temperature, accelerated precipitation kinetics of carbonitrides. With decreasing the finishing temperature and coiling temperature, the precipitates volume fraction increases and strength increment is raised during hot rolling. The simulated results are in agreementwith experiment results.

  8. Mechanisms and kinetics of precipitate restructuring during irradiation

    International Nuclear Information System (INIS)

    Potter, D.I.; Wiedersich, H.

    1979-01-01

    Irradiations were performed at temperatures from 400 to 700 0 C using 3.0-MeV 58 Ni + ions in order to investigate γ'-precipitate restructuring in two model alloys: Ni-12.8 at% Al and Ni-12.7 at% Si. The precipitates coarsened, with the third power of the average diameter proportional to the damage dose. The temperature dependence of the rate constants for irradiated specimens is described in terms of a modified Lifschitz-Slyozov-Wagner coarsening model that includes radiation-enhanced diffusion. Redistribution of precipitate by enhanced precipitation (Ni-Si) or precipitate dissolution (Ni-Al) at point-defect sinks caused maxima in γ' size with dose. Precipitate redistribution at the free surfaces of irradiated thin foils and at γ/γ' particle interfaces is described. (Auth.)

  9. Invasion of Old World Phragmites australis in the New World: precipitation and temperature patterns combined with human influences redesign the invasive niche

    DEFF Research Database (Denmark)

    Guo, Wen-Yong; Lambertini, Carla; Li, Xiu-Zhen

    2013-01-01

    niches. We suggest that an increase in precipitation in the 20(th) century, global warming and human-made habitats have shaped the invasive niches of the two lineages in the New World. However, as the invasions are on-going and human and natural disturbances occur concomitantly, the future distribution....... australis (Haplotype M and Med) in both their native and introduced ranges using environmental niche models (ENMs) to assess (i) whether a niche shift accompanied the invasions in the New World; (ii) the role of biologically relevant climatic variables and human influence in the process of invasion...... for temperature fluctuations and increased precipitation. The introduced Med lineage has enlarged its original subtropical niche to the tropics-subtropics, invading regions with a high annual mean temperature (> c. 10 °C) and high precipitation in the driest period. Human influence is an important factor for both...

  10. Effect of steeping temperature on antioxidant and inhibitory activities of green tea extracts against α-amylase, α-glucosidase and intestinal glucose uptake.

    Science.gov (United States)

    Liu, Shuyuan; Ai, Zeyi; Qu, Fengfeng; Chen, Yuqiong; Ni, Dejiang

    2017-11-01

    The objective of the present study was to evaluate the effect of steeping temperature on the biological activities of green tea, including the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging capacity, α-glucosidase and α-amylase inhibitory activities, and glucose uptake inhibitory activity in Caco-2 cells. Results showed that, with increasing extraction temperature, the polyphenol content increased, which contributed to enhance antioxidant activity and inhibitory effects on α-glucosidase and α-amylase. Green tea steeped at 100°C showed the highest DPPH radical-scavenging activity and inhibitory effects on α-glucosidase and α-amylase activities with EC 50 or IC 50 values of 6.15μg/mL, 0.09mg/mL, and 6.31mg/mL, respectively. However, the inhibitory potential on glucose uptake did not show an upward trend with increasing extraction temperature. Green tea steeped at 60°C had significantly stronger glucose uptake inhibitory activity (ptea. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Precipitation Climatology on Titan-like Exomoons.

    Science.gov (United States)

    Tokano, Tetsuya

    2015-06-01

    The availability of liquid water on the surface on Earth's continents in part relies on the precipitation of water. This implies that the habitability of exomoons has to consider not only the surface temperature and atmospheric pressure for the presence of liquid water, but also the global precipitation climatology. This study explores the sensitivity of the precipitation climatology of Titan-like exomoons to these moons' orbital configuration using a global climate model. The precipitation rate primarily depends on latitude and is sensitive to the planet's obliquity and the moon's rotation rate. On slowly rotating moons the precipitation shifts to higher latitudes as obliquity is increased, whereas on quickly rotating moons the latitudinal distribution does not strongly depend on obliquity. Stellar eclipse can cause a longitudinal variation in the mean surface temperature and surface pressure between the subplanetary and antiplanetary side if the planet's obliquity and the moon's orbital distance are small. In this particular condition the antiplanetary side generally receives more precipitation than the subplanetary side. However, precipitation on exomoons with dense atmospheres generally occurs at any longitude in contrast to tidally locked exoplanets.

  12. Heating-insensitive scale increase caused by convective precipitation

    Science.gov (United States)

    Haerter, Jan; Moseley, Christopher; Berg, Peter

    2017-04-01

    The origin of intense convective extremes and their unusual temperature dependence has recently challenged traditional thermodynamic arguments, based on the Clausius-Clapeyron relation. In a sequence of studies (Lenderink and v. Mejgaard, Nat Geosc, 2008; Berg, Haerter, Moseley, Nat Geosc, 2013; and Moseley, Hohenegger, Berg, Haerter, Nat Geosc, 2016) the argument of convective-type precipitation overcoming the 7%/K increase in extremes by dynamical, rather than thermodynamic, processes has been promoted. How can the role of dynamical processes be approached for precipitating convective cloud? One-phase, non-precipitating Rayleigh-Bénard convection is a classical problem in complex systems science. When a fluid between two horizontal plates is sufficiently heated from below, convective rolls spontaneously form. In shallow, non-precipitating atmospheric convection, rolls are also known to form under specific conditions, with horizontal scales roughly proportional to the boundary layer height. Here we explore within idealized large-eddy simulations, how the scale of convection is modified, when precipitation sets in and intensifies in the course of diurnal solar heating. Before onset of precipitation, Bénard cells with relatively constant diameter form, roughly on the scale of the atmospheric boundary layer. We find that the onset of precipitation then signals an approximately linear (in time) increase in horizontal scale. This scale increase progresses at a speed which is rather insensitive to changes in surface temperature or changes in the rate at which boundary conditions change, hinting at spatial characteristics, rather than temperature, as a possible control on spatial scales of convection. When exploring the depth of spatial correlations, we find that precipitation onset causes a sudden disruption of order and a subsequent complete disintegration of organization —until precipitation eventually ceases. Returning to the initial question of convective

  13. Green lights

    DEFF Research Database (Denmark)

    Fisker, Peter Kielberg

    This study investigates the effect of drought on economic activity globally using remote sensing data. In particular, predicted variation in greenness is correlated with changes in the density of artificial light observed at night on a grid of 0.25 degree latitude-longitude pixels. I define drought...... as greenness estimated by lagged variation in monthly rainfall and temperature. This definition of drought performs well in identifying self-reported drought events since 2000 compared with measures of drought that do not take greenness into account, and the subsequent analysis indicates that predicted...... variation in greenness is positively associated with year-on-year changes in luminosity: If a unit of observation experiences a predicted variation in greenness that lies 1 standard deviation below the global mean, on average 1.5 - 2.5 light pixels out of 900 are extinguished that year. Finally, an attempt...

  14. Meta-analysis of changes in temperature and precipitation in Florida in the context of food-energy-water nexus

    Science.gov (United States)

    Anandhi, A.; Sharma, A.

    2017-12-01

    Florida is a hotspot of endemism for plants, vertebrates, and insects outside of the tropics. The state has extensive coastline, with the maximum distance from the coast less than 150 km which has diverse ecosystems and landscapes, as well as habitat for many endangered species. Additionally, agriculture is one of the most important economic resources in Florida and is ranked second in the U.S. for value of vegetable production. Florida's biodiversity is threatened by stressors such as increasing urbanization and population, land-use change and socio-economic growth. Given that, climate change and variability will interact with these stresses, potentially accentuating their negative impacts, there are several studies, concerning climate change impacts on Florida's ecosystem to date. The specific objectives of this study were to demonstrate the decision support tool developed from meta-analysis. The Tool was developed using the temperature and precipitation changes in Florida identified from peer reviewed studies. These change values were then synthesized using simple statistical techniques (e.g., histogram, line plots and density plots). Our results indicate a wide variability in the temperature and precipitation changes observed in the studies for Florida. The studies showed a temperature change ranged between +5 °C and -3 °C, while the precipitation change ranged between +30% and -40% in the state. These changes have series implications on the food-water-energy nexus. Some of the potential implications of these changes in the context of the nexus are discussed using causal chains developed from meta-analysis.

  15. Intense air-sea exchanges and heavy orographic precipitation over Italy: The role of Adriatic sea surface temperature uncertainty

    Science.gov (United States)

    Stocchi, Paolo; Davolio, Silvio

    2017-11-01

    Strong and persistent low-level winds blowing over the Adriatic basin are often associated with intense precipitation events over Italy. Typically, in case of moist southeasterly wind (Sirocco), rainfall affects northeastern Italy and the Alpine chain, while with cold northeasterly currents (Bora) precipitations are localized along the eastern slopes of the Apennines and central Italy coastal areas. These events are favoured by intense air-sea interactions and it is reasonable to hypothesize that the Adriatic sea surface temperature (SST) can affect the amount and location of precipitation. High-resolution simulations of different Bora and Sirocco events leading to severe precipitation are performed using a convection-permitting model (MOLOCH). Sensitivity experiments varying the SST initialization field are performed with the aim of evaluating the impact of SST uncertainty on precipitation forecasts, which is a relevant topic for operational weather predictions, especially at local scales. Moreover, diagnostic tools to compute water vapour fluxes across the Italian coast and atmospheric water budget over the Adriatic Sea have been developed and applied in order to characterize the air mass that feeds the precipitating systems. Finally, the investigation of the processes through which the SST influences location and intensity of heavy precipitation allows to gain a better understanding on mechanisms conducive to severe weather in the Mediterranean area and in the Adriatic basin in particular. Results show that the effect of the Adriatic SST (uncertainty) on precipitation is complex and can vary considerably among different events. For both Bora and Sirocco events, SST does not influence markedly the atmospheric water budget or the degree of moistening of air that flows over the Adriatic Sea. SST mainly affects the stability of the atmospheric boundary layer, thus influencing the flow dynamics and the orographic flow regime, and in turn, the precipitation pattern.

  16. Precipitation behaviors of X70 acicular ferrite pipeline steel

    Institute of Scientific and Technical Information of China (English)

    Hao Yu; Yi Sun; Qixiang Chen; Haitao Jiang; Lihong Zhang

    2006-01-01

    The morphology, structure, and chemical composition of precipitates in the final microstructure of Nb-V-Ti microalloyed X70 acicular ferrite pipeline steel were investigated using transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). Precipitates observed by TEM can be classified into two groups. The large precipitates are complex compounds that comprise square-shaped TiN precipitate as core with fine Nb-containing precipitate nucleated on pre-existing TiN precipitate as caps on one or more faces at high temperature. In contrast, the fine and spherical Nb carbides and/or carbonitrides precipitate heterogeneously on dislocations and sub-boundaries at low temperature. From the analysis in terms of thermodynamics, EDS and chemical composition of the steel, NbC precipitation is considered to be the predominant precipitation behavior in the tested steel under the processing conditions of this research.

  17. Sustainable and efficient allocation of limited blue and green water resources

    OpenAIRE

    Schyns, Joseph Franciscus

    2018-01-01

    Freshwater stems from precipitation over land, which differentiates into a blue water flow (groundwater and surface water) and a green water flow (evaporation). Both flows are partially allocated to serve the economy, resulting in blue and green water footprints (WF). There are maximum sustainable levels to the blue and green WF, since rainfall is limited and part of the flows need to be reserved for aquatic and terrestrial biodiversity. Water scarcity, the degree to which the actual approach...

  18. The determining impact of coiling temperature on the microstructure and mechanical properties of a titanium-niobium ultrahigh strength microalloyed steel: Competing effects of precipitation and bainite

    Energy Technology Data Exchange (ETDEWEB)

    Natarajan, V.V.; Challa, V.S.A. [Laboratory for Excellence in Advanced Steel Research, Materials Science and Engineering Program, Department of Metallurgical, Materials and Biomedical Engineering, 500 W. University Avenue, University of Texas at El Paso, El Paso, TX 79968 (United States); Misra, R.D.K., E-mail: dmisra2@utep.edu [Laboratory for Excellence in Advanced Steel Research, Materials Science and Engineering Program, Department of Metallurgical, Materials and Biomedical Engineering, 500 W. University Avenue, University of Texas at El Paso, El Paso, TX 79968 (United States); Sidorenko, D.M.; Mulholland, M.D.; Manohar, M.; Hartmann, J.E. [ArcelorMittal Global R& D Center, 3001 East Columbus Drive, East Chicago, IN 46312 (United States)

    2016-05-17

    We elucidate here the influence of coiling temperature on the microstructure and mechanical properties, in an ultrahigh strength titanium-niobium microalloyed steel. The objective was to underscore the impact of coiling temperature on the nature and distribution of microstructural constituents (including different phases, precipitates, and dislocation structure) that significantly contributed to differences in the yield and tensile strength of these steels. Depending on the coiling temperature, the microstructure consisted of either a combination of fine lath-type bainite and polygonal ferrite or polygonal ferrite together with the precipitation of microalloyed carbides of size ~2–10 nm in the matrix and at dislocations. The microstructure of steel coiled at lower temperature predominantly consisted of bainitic ferrite with lower yield strength compared to the steel coiled at higher temperature, and the yield to tensile strength ratio was 0.76. The steel coiled at higher temperature consisted of polygonal ferrite and extensive precipitation of carbides and was characterized by higher yield strength and with yield strength/tensile strength ratio of 0.936. The difference in the tensile strength was insignificant for the two coiling temperatures. The observed microstructure was consistent with the continuous cooling transformation diagram.

  19. Impacts of precipitation and temperature trends on different time scales on the water cycle and water resource availability in mountainous Mediterranean catchments.

    Science.gov (United States)

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

    2017-04-01

    Climatology trends, precipitation and temperature variations condition the hydrological evolution of the river flow response at basin and sub-basin scales. The link between both climate and flow trends is crucial in mountainous areas, where small variations in temperature can produce significant impacts on precipitation (occurrence as rainfall or snowfall), snowmelt and evaporation, and consequently very different flow signatures. This importance is greater in semiarid regions, where the high variability of the climatic annual and seasonal regimes usually amplifies this impact on river flow. The Sierra Nevada National Park (Southern Spain), with altitudes ranging from 2000 to 3500 m.a.s.l., is part of the global climate change observatories network and a clear example of snow regions in a semiarid environment. This mountain range is head of different catchments, being the Guadalfeo River Basin one of the most influenced by the snow regime. This study shows the observed 55-year (1961-2015) trends of annual precipitation and daily mean temperature, and the associated impacts on snowfall and snow persistence, and the resulting trend of the annual river flow in the Guadalfeo River Basin (Southern Spain), a semiarid abrupt mountainous area (up to 3450 m a.s.l.) facing the Mediterranean Sea where the Alpine and Mediterranean climates coexist in a domain highly influenced by the snow regime, and a significant seasonality in the flow regime. The annual precipitation and annual daily mean temperature experimented a decreasing trend of 2.05 mm/year and an increasing trend of 0.037 °C/year, respectively, during the study period, with a high variability on a decadal basis. However, the torrential precipitation events are more frequent in the last few years of the study period, with an apparently increasing associated dispersion. The estimated annual snowfall trend shows a decreasing trend of 0.24 mm/year, associated to the decrease of precipitation rather than to temperature

  20. Continuous precipitation process of plutonium salts; Procede continu de precipitation des sels de plutonium

    Energy Technology Data Exchange (ETDEWEB)

    Richard, P [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1967-03-01

    This work concerns the continuous precipitation process of plutonium oxalate. Investigations about the solubility of different valence states in nitric-oxalic and in nitric-sulfuric-oxalic medium lead to select the precipitation process of tetravalent plutonium oxalate. Settling velocity and granulometry of tetravalent oxalate plutonium have been studied with variation of several precipitation parameters such as: temperature, acidity, excess of oxalic acid and aging time. Then are given test results of some laboratory continuous apparatus. Conditions of operation with adopted tubular apparatus are defined in conclusion. A flow-sheet is given for a process at industrial scale. (author) [French] Cette etude porte sur la precipitation continue de l'oxalate de plutonium. L'etude de la solubilite des differentes valences du plutonium dans des milieux acides nitrique-oxalique, puis nitrique-sulfurique-oxalique conduit a choisir la precipitation de l'oxalate de plutonium tetravalent. L'etude porte ensuite sur la sedimentation et la granulometrie de l'oxalate de Pu{sup 4+} obtenue en faisant varier differents parametres de la precipitation : la temperature, l'acidite, l'exces oxalique et le temps de murissement. La derniere partie traite des resultats obtenus avec plusieurs types d'appareils continus essayes au laboratoire. En conclusion sont donnees les conditions de marche de l'appareil tubulaire adopte, ainsi qu'une extrapolation a l'echelle industrielle sous forme d'un flow-sheet. (auteur)

  1. Sea surface salinity and temperature-based predictive modeling of southwestern US winter precipitation: improvements, errors, and potential mechanisms

    Science.gov (United States)

    Liu, T.; Schmitt, R. W.; Li, L.

    2017-12-01

    Using 69 years of historical data from 1948-2017, we developed a method to globally search for sea surface salinity (SSS) and temperature (SST) predictors of regional terrestrial precipitation. We then applied this method to build an autumn (SON) SSS and SST-based 3-month lead predictive model of winter (DJF) precipitation in southwestern United States. We also find that SSS-only models perform better than SST-only models. We previously used an arbitrary correlation coefficient (r) threshold, |r| > 0.25, to define SSS and SST predictor polygons for best subset regression of southwestern US winter precipitation; from preliminary sensitivity tests, we find that |r| > 0.18 yields the best models. The observed below-average precipitation (0.69 mm/day) in winter 2015-2016 falls within the 95% confidence interval of the prediction model. However, the model underestimates the anomalous high precipitation (1.78 mm/day) in winter 2016-2017 by more than three-fold. Moisture transport mainly attributed to "pineapple express" atmospheric rivers (ARs) in winter 2016-2017 suggests that the model falls short on a sub-seasonal scale, in which case storms from ARs contribute a significant portion of seasonal terrestrial precipitation. Further, we identify a potential mechanism for long-range SSS and precipitation teleconnections: standing Rossby waves. The heat applied to the atmosphere from anomalous tropical rainfall can generate standing Rossby waves that propagate to higher latitudes. SSS anomalies may be indicative of anomalous tropical rainfall, and by extension, standing Rossby waves that provide the long-range teleconnections.

  2. MODELING OF STRAIN-INDUCED PRECIPITATION KINETICS IN Nb MICROALLOYED STEELS

    Institute of Scientific and Technical Information of China (English)

    X.G. Zhou; Z.Y. Liu; D. Wu; Z.Li; C.M. Li

    2006-01-01

    On the basis of the thermodynamic calculation of precipitation and considering the effect of strain on the precipitation behavior and chemical composition (Si and Mn), the kinetics of precipitation from austenite has been investigated for different temperatures and strains. Nucleation theory and the solubility product of niobium, carbon, and nitrogen in austenite have been used to derive equations for the start time of precipitation as a function of temperature and composition. The value of n in Avrami equation was determined using the available experimental data from the published reports, which indicated that n is a constant independent of temperature and the end time of precipitation is a function of n and the start time of precipitation. The values of the start time and end time of precipitation predicted by the new model are compared with the experimental values and a good agreement was obtained between both.

  3. Optical solar energy adaptations and radiative temperature control of green leaves and tree barks

    Energy Technology Data Exchange (ETDEWEB)

    Henrion, Wolfgang; Tributsch, Helmut [Department of Si-Photovoltaik and Solare Energetik, Hahn-Meitner-Institut Berlin, 14109 Berlin (Germany)

    2009-01-15

    Trees have adapted to keep leaves and barks cool in sunshine and can serve as interesting bionic model systems for radiative cooling. Silicon solar cells, on the other hand, loose up to one third of their energy efficiency due to heating in intensive sunshine. It is shown that green leaves minimize absorption of useful radiation and allow efficient infrared thermal emission. Since elevated temperatures are detrimental for tensile water flow in the Xylem tissue below barks, the optical properties of barks should also have evolved so as to avoid excessive heating. This was tested by performing optical studies with tree bark samples from representative trees. It was found that tree barks have optimized their reflection of incoming sunlight between 0.7 and 2 {mu}m. This is approximately the optical window in which solar light is transmitted and reflected by green vegetation. Simultaneously, the tree bark is highly absorbing and thus radiation emitting between 6 and 10 {mu}m. These two properties, mainly provided by tannins, create optimal conditions for radiative temperature control. In addition, tannins seem to have adopted a function as mediators for excitation energy towards photo-antioxidative activity for control of radiation damage. The results obtained are used to discuss challenges for future solar cell optimization. (author)

  4. THE EFFECTS OF BUILT-UP AND GREEN AREAS ON THE LAND SURFACE TEMPERATURE OF THE KUALA LUMPUR CITY

    Directory of Open Access Journals (Sweden)

    N. A. Isa

    2017-10-01

    Full Text Available A common consequence of rapid and uncontrollable urbanization is Urban Heat Island (UHI. It occurs due to the negligence on climate behaviour which degrades the quality of urban climate condition. Recently, addressing urban climate in urban planning through mapping has received worldwide attention. Therefore, the need to identify the significant factors is a must. This study aims to analyse the relationships between Land Surface Temperature (LST and two urban parameters namely built-up and green areas. Geographical Information System (GIS and remote sensing techniques were used to prepare the necessary data layers required for this study. The built-up and the green areas were extracted from Landsat 8 satellite images either using the Normalized Difference Built-Up Index (NDBI, Normalized Difference Vegetation Index (NDVI or Modified Normalize Difference Water Index (MNDWI algorithms, while the mono-window algorithm was used to retrieve the Land Surface Temperature (LST. Correlation analysis and Multi-Linear Regression (MLR model were applied to quantitatively analyse the effects of the urban parameters. From the study, it was found that the two urban parameters have significant effects on the LST of Kuala Lumpur City. The built-up areas have greater influence on the LST as compared to the green areas. The built-up areas tend to increase the LST while green areas especially the densely vegetated areas help to reduce the LST within an urban areas. Future studies should focus on improving existing urban climatic model by including other urban parameters.

  5. Spatiotemporal Variability and Covariability of Temperature, Precipitation, Soil Moisture, and Vegetation in North America for Regional Climate Model Applications

    Science.gov (United States)

    Castro, C. L.; Beltran-Przekurat, A. B.; Pielke, R. A.

    2007-05-01

    Previous work has established that the dominant modes of Pacific SSTs influence the summer climate of North America through large-scale forcing, and this effect is most pronounced during the early part of the season. It is hypothesized, then, that land surface influences become more dominant in the latter part of the season as remote teleconnection influences diminish. As a first step toward investigation of this hypothesis in a regional climate model (RCM) framework, the statistically signficant spatiotemporal patterns of variability and covariability in North American precipitation (specified by the standardized precipitation index, or SPI), soil moisture, and vegetation are determined for timescales from a month to six months. To specify these respective data we use: CPC gauge- derived precipitation (1950-2000), Variable Infiltration Capacity (VIC) Model and NOAH Model NLDAS soil moisture and temperature, and the Global Inventory Modeling and Mapping Studies Normalized Difference Vegetation Index (GIMMS-NDVI). The principal statistical tool used is multiple taper frequency singular value decomposition (MTM-SVD), and this is supplemented by wavelet analysis for specific areas of interest. The significant interannual variability in all of these data occur at a timescale of about 7 to 9 years and appears to be the integrated effect of remote SST forcing from the Pacific. Considering the entire year, the spatial pattern for precipitation resembles the typical ENSO winter signature. If the summer season is considered seperately, the out of phase relationship between precipitation anomalies in the central U.S. and core monsoon region is apparent. The largest soil moisture anomalies occur in the central U.S., since precipitation in this region has a consistent relationship to Pacific SSTs for the entire year. This helps to explain the approximately 20 year periodicity in drought conditions there. Unlike soil moisture, the largest anomalies in vegetation occur in the

  6. Development of Colletotrichum gloeosporioides isolated from green pepper in different culture media, temperatures, and light regimes

    Directory of Open Access Journals (Sweden)

    Mello Alexandre Furtado Silveira

    2004-01-01

    Full Text Available Control of anthracnose in green pepper involves the use of resistant varieties and/or fungicides. The selection of varieties and efficient products demands great amounts of conidia as inoculum. It is thus necessary to optimize the production of Colletotrichum gloeosporioides conidia in the laboratory, establishing the best conditions for fungus development. The present study aimed at determining the most favorable culture media, temperature, and light conditions for the production of fungus inoculum. The fungus was isolated from green pepper fruits (Capsicum annuum L. and transferred to four culture media (PDA, oat, filtered pepper extract, and autoclaved pepper extract, under different temperatures (15, 20, 25, 30, and 35ºC and light conditions (24h dark, and 24h light. Colony growth was evaluated after 7 and 12 days of incubation. No differences were found between the culture media. However, the greatest number of conidia was obtained from colonies grown in oat medium at 25ºC. Temperatures of 20 and 25ºC were the most favorable for colony growth and sporulation. Higher sporulation was obtained under incubation in constant light. Cultivation of C. gloeosporioides in oat medium, at 25ºC, and constant light is recommended.

  7. Precipitation and air temperature control the variations of dissolved organic matter along an altitudinal forest gradient, Gongga Mountains, China.

    Science.gov (United States)

    Hu, Zhaoyong; Wang, Genxu; Sun, Xiangyang

    2017-04-01

    Dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) contribute significantly to C and N cycling in forest ecosystems. Little information is available on the variations in the DOC and DON concentrations and depositions in bulk and stand precipitation within forests along an altitudinal gradient. To determine the temporal variations in the DOC and DON concentrations and depositions in different forests and the spatial variations along the elevation gradient, the DOC and DON concentrations and depositions were measured in bulk precipitation, throughfall, and stemflow within three forest types, i.e., broadleaf forest (BLF), broadleaf-coniferous forest (BCF), and coniferous forest (CF), during the wet season (May to October) on Gongga Mountain, China, in 2015. The concentrations of bulk precipitation in BLF, BCF, and CF were 3.92, 4.04, and 2.65 mg L -1 , respectively, for DOC and were 0.38, 0.26, and 0.29 mg L -1 , respectively, for DON. BCF had the highest DOC deposition both in bulk precipitation (45.12 kg ha -1 ) and stand precipitation (98.52 kg ha -1 ), whereas the highest DON deposition was in BLF (3.62 kg ha -1 bulk precipitation and 4.11 kg ha -1 stand precipitation) during the study period. The meteorological conditions of precipitation and air temperature significantly influenced the dissolved organic matter (DOM) depositions along the elevation gradient. The leaf area index did not show any correlation with DOM depositions during the growing season.

  8. "Cool" vs. "warm" winter precipitation and its effect on streamflow in California

    OpenAIRE

    Cayan, Daniel R.

    1991-01-01

    Precipitation is a difficult variable to understand and predict. In this study, monthly precipitation in California is divided into two classes according to the monthly temperature to better diagnose the atmospheric circulation that causes precipitation, and to illustrate how temperature compounds the precipitation to runoff process.

  9. Soil respiration patterns and rates at three Taiwanese forest plantations: dependence on elevation, temperature, precipitation, and litterfall.

    Science.gov (United States)

    Huang, Yu-Hsuan; Hung, Chih-Yu; Lin, I-Rhy; Kume, Tomonori; Menyailo, Oleg V; Cheng, Chih-Hsin

    2017-11-15

    Soil respiration contributes to a large quantity of carbon emissions in the forest ecosystem. In this study, the soil respiration rates at three Taiwanese forest plantations (two lowland and one mid-elevation) were investigated. We aimed to determine how soil respiration varies between lowland and mid-elevation forest plantations and identify the relative importance of biotic and abiotic factors affecting soil respiration. The results showed that the temporal patterns of soil respiration rates were mainly influenced by soil temperature and soil water content, and a combined soil temperature and soil water content model explained 54-80% of the variation. However, these two factors affected soil respiration differently. Soil temperature positively contributed to soil respiration, but a bidirectional relationship between soil respiration and soil water content was revealed. Higher soil moisture content resulted in higher soil respiration rates at the lowland plantations but led to adverse effects at the mid-elevation plantation. The annual soil respiration rates were estimated as 14.3-20.0 Mg C ha -1  year -1 at the lowland plantations and 7.0-12.2 Mg C ha -1  year -1 at the mid-elevation plantation. When assembled with the findings of previous studies, the annual soil respiration rates increased with the mean annual temperature and litterfall but decreased with elevation and the mean annual precipitation. A conceptual model of the biotic and abiotic factors affecting the spatial and temporal patterns of the soil respiration rate was developed. Three determinant factors were proposed: (i) elevation, (ii) stand characteristics, and (iii) soil temperature and soil moisture. The results indicated that changes in temperature and precipitation significantly affect soil respiration. Because of the high variability of soil respiration, more studies and data syntheses are required to accurately predict soil respiration in Taiwanese forests.

  10. 'Green' synthesis of starch capped CdSe nanoparticles at room temperature

    International Nuclear Information System (INIS)

    Li Jinhua; Ren Cuiling; Liu Xiaoyan; Hu Zhide; Xue Desheng

    2007-01-01

    The nearly monodisperse starch capped CdSe nanoparticles were successfully synthesized by a simple and 'green' route at room temperature. The as-prepared nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), UV-vis absorption and photoluminescence (PL) spectra. The XRD analysis showed that the starch capped CdSe nanoparticles were of the cubic structure, the average particle size was calculated to be about 3 nm according to the Debye-Scherrer equation. TEM micrographs exhibited that the starch capped CdSe nanoparticles were well dispersed than the uncapped CdSe nanoparticles, the mean particles size of the capped CdSe was about 3 nm in the TEM image, which was in good agreement with the XRD

  11. High solar-light photocatalytic activity of using Cu3Se2/rGO nanocomposites synthesized by a green co-precipitation method

    Science.gov (United States)

    Nouri, Morteza; Saray, Abdolali Moghaddam; Azimi, H. R.; Yousefi, Ramin

    2017-11-01

    Current work presents a facile, cost-effective, and green method to synthesize copper selenide nanostructures and copper selenide/graphene nanocomposites. The products were synthesized by a co-precipitation method by glycine amino acid as a green surfactant and graphene oxide (GO) sheets as a graphene source. X-ray diffraction patterns (XRD) of the products indicated that the products were Cu2Se3 with tetragonal phase. Fourier transform infrared (FTIR) spectroscopy and the XRD patterns indicated that the GO sheets were changed into reduced GO (rGO) during the synthesis process. Scanning and transmission electron microscopy (SEM and TEM) images showed the nanoparticles (NPs) that were decorated on rGO sheets had the significantly smaller size in compared to the pristine NPs. UV-vis results revealed that, the absorption peak of the products were in the visible region with a band-gap value between 1.85 eV and 1.95 eV. Finally, the products were applied as photocatalytic materials to remove Methylene Blue (MB) dye under solar-light and visible-light irradiation conditions. It was observed; the rGO had a significant role in enhancing the photocatalytic performance of the products and Cu2Se3/rGO (15%) could degrade more than 91% and 73% of MB only during 1 h under solar-light and visible-light sources, respectively.

  12. Response of soil CO2 efflux to precipitation manipulation in a semiarid grassland.

    Science.gov (United States)

    Wei, Xiaorong; Zhang, Yanjiang; Liu, Jian; Gao, Hailong; Fan, Jun; Jia, Xiaoxu; Cheng, Jimin; Shao, Mingan; Zhang, Xingchang

    2016-07-01

    Soil CO2 efflux (SCE) is an important component of ecosystem CO2 exchange and is largely temperature and moisture dependent, providing feedback between C cycling and the climate system. We used a precipitation manipulation experiment to examine the effects of precipitation treatment on SCE and its dependences on soil temperature and moisture in a semiarid grassland. Precipitation manipulation included ambient precipitation, decreased precipitation (-43%), or increased precipitation (+17%). The SCE was measured from July 2013 to December 2014, and CO2 emission during the experimental period was assessed. The response curves of SCE to soil temperature and moisture were analyzed to determine whether the dependence of SCE on soil temperature or moisture varied with precipitation manipulation. The SCE significantly varied seasonally but was not affected by precipitation treatments regardless of season. Increasing precipitation resulted in an upward shift of SCE-temperature response curves and rightward shift of SCE-moisture response curves, while decreasing precipitation resulted in opposite shifts of such response curves. These shifts in the SCE response curves suggested that increasing precipitation strengthened the dependence of SCE on temperature or moisture, and decreasing precipitation weakened such dependences. Such shifts affected the predictions in soil CO2 emissions for different precipitation treatments. When considering such shifts, decreasing or increasing precipitation resulted in 43 or 75% less change, respectively, in CO2 emission compared with changes in emissions predicted without considering such shifts. Furthermore, the effects of shifts in SCE response curves on CO2 emission prediction were greater during the growing than the non-growing season. Copyright © 2016. Published by Elsevier B.V.

  13. Study on Thorium Hidroxide and Ammonium Diuranate precipitation

    International Nuclear Information System (INIS)

    Damunir; Sukarsono, R; Busron-Masduki; Indra-Suryawan

    1996-01-01

    Thorium hydroxide and ammonium diuranate precipitation studied by the reaction of mixed thorium nitrate and uranyl nitrate using ammonium hydroxide. The purposes of this research was study of pH condition. U/Th ratio and NH 4 OH concentration on the precipitation. Mixed of thorium nitrate and uranyl nitrate 50 ml was reacted by excess ammonium hydroxide 2 - 10 M, pH 4-8, 40-80 o C of temperature and 5 - 100 % ratio of U/Th. The best of precipitation depend on thorium and uranium content on the precipitation. The experiment result for the best condition of precipitation was 25 % of ratio U/Th, pH 6 - 8, 60-80 o C of temperature, and 6 - 10 M concentration of ammonium hydroxide, was produced precipitate by 3,938 - 5,455 weight percent of mean concentration of U and 22,365-31,873 weight percent of mean concentration of Th

  14. Molecular records of continental air temperature and monsoon precipitation variability in East Asia spanning the past 130,000 years

    NARCIS (Netherlands)

    Peterse, F.; Martínez-García, A.; Zhou, B.; Beets, C.J.; Prins, M.A.; Zheng, H.; Eglinton, T.I.

    2014-01-01

    Our current understanding of past changes in East Asian summer monsoon (EASM) precipitation intensity derives from several loess–paleosol sequences and oxygen isotope (δ18O) records of well-dated stalagmites. Although temperature is generally presumed to have had minimal impact on EASM records, past

  15. Precipitation Kinetics of Cr2N in High Nitrogen Austenitic Stainless Steel

    Institute of Scientific and Technical Information of China (English)

    SHI Feng; WANG Li-jun; CUI Wen-fang; LIU Chun-ming

    2008-01-01

    The precipitation behavior of Cr2N during isothermal aging in the temperature range from 700℃to 950℃ in Fe-18Cr-12Mn-0.48N(in mass percent)high nitrogen austenitic stainless steel,including morphology and content of precipitate,was investigated using optical microscopy,scanning electron microscopy,and transmission electron microscopy.The isothermal precipitation kinetics curve of Cr2N and the corresponding precipitation activation energy were obtained.The results show that Cr2N phase precipitates in a cellular way and its morphology is transformed from initial granular precipitates to lamellar ones in the cell with increasing aging time.The nose temperature of Cr2N precipitation is about 800℃,with a corresponding incubation period of 30 min,and the ceiling temperature of Cr2N precipitation is 950℃.The diffusion activation energy of Cr2N precipitation is 296 kJ/mol.

  16. Decadal Shift in West China Autumn Precipitation and its Association With Sea Surface Temperature

    Science.gov (United States)

    Wei, Ting; He, Shengping; Yan, Qing; Dong, Wenjie; Wen, Xiaohang

    2018-01-01

    West China autumn precipitation (WCAP) is the final stage of the rainy season in mainland China and is characterized as the secondary peak in annual cycle of precipitation in West China. This study reveals that WCAP experienced a significant interdecadal shift around the mid-1980s, with greatly reduced precipitation after this shift. Features related to the decrease in WCAP include the weakening of warm, wet southerlies prevailing from the oceans to inland China, the weakened Eurasian pattern, and the southward displacement of the East Asian jet stream (EAJS). Further analysis indicates that the interdecadal changes in WCAP may be attributed to the interdecadal increasing of sea surface temperature (SST) in the Indo-Pacific warm pool (SSTIOP), North Pacific (SSTNP), and central equatorial Pacific (SSTCEP) after the 1980s. The warmer SSTIOP contributes to a weaker meridional land-sea thermal contrast, which inducts an anomalous local meridional circulation and northerly. The warmer SSTNP stimulates a Rossby wave train that leads to weakened West Pacific subtropical high and accompanying cyclonic circulation anomaly, hindering the transport of water vapor inland from the oceans. The increased SSTCEP leads to the southward displacement of the EAJS and its secondary circulation, generating an anomalous descending branch and reduced WCAP. Numerical simulations further support the conclusions derived from the diagnostic analysis that the decadal warming of the SSTIOP, SSTNP, and SSTCEP synergistically contributes to the reduction of WCAP after the 1980s.

  17. A Combined Precipitation, Yield Stress, and Work Hardening Model for Al-Mg-Si Alloys Incorporating the Effects of Strain Rate and Temperature

    Science.gov (United States)

    Myhr, Ole Runar; Hopperstad, Odd Sture; Børvik, Tore

    2018-05-01

    In this study, a combined precipitation, yield strength, and work hardening model for Al-Mg-Si alloys known as NaMo has been further developed to include the effects of strain rate and temperature on the resulting stress-strain behavior. The extension of the model is based on a comprehensive experimental database, where thermomechanical data for three different Al-Mg-Si alloys are available. In the tests, the temperature was varied between 20 °C and 350 °C with strain rates ranging from 10-6 to 750 s-1 using ordinary tension tests for low strain rates and a split-Hopkinson tension bar system for high strain rates, respectively. This large span in temperatures and strain rates covers a broad range of industrial relevant problems from creep to impact loading. Based on the experimental data, a procedure for calibrating the different physical parameters of the model has been developed, starting with the simplest case of a stable precipitate structure and small plastic strains, from which basic kinetic data for obstacle limited dislocation glide were extracted. For larger strains, when work hardening becomes significant, the dynamic recovery was linked to the Zener-Hollomon parameter, again using a stable precipitate structure as a basis for calibration. Finally, the complex situation of concurrent work hardening and dynamic evolution of the precipitate structure was analyzed using a stepwise numerical solution algorithm where parameters representing the instantaneous state of the structure were used to calculate the corresponding instantaneous yield strength and work hardening rate. The model was demonstrated to exhibit a high degree of predictive power as documented by a good agreement between predictions and measurements, and it is deemed well suited for simulations of thermomechanical processing of Al-Mg-Si alloys where plastic deformation is carried out at various strain rates and temperatures.

  18. Stability of TaC precipitates in a Co-Re-based alloy being developed for ultra-high-temperature applications

    Czech Academy of Sciences Publication Activity Database

    Gilles, R.; Mukherji, D.; Karge, L.; Strunz, Pavel; Beran, Přemysl; Barbier, B.; Kriele, A.; Hofmann, M.; Eckerlebe, H.; Rösler, J.

    2016-01-01

    Roč. 49, č. 4 (2016), s. 1253-1265 ISSN 1600-5767 R&D Projects: GA ČR GB14-36566G Institutional support: RVO:61389005 Keywords : high-temperature alloys * precipitates * small-angle neutron scattering * phase transformation * X-ray diffraction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.495, year: 2016

  19. Exploring the role of green and blue infrastructure in reducing temperature in Iskandar Malaysia using remote sensing approach

    International Nuclear Information System (INIS)

    Kanniah, K D; Sheikhi, A; Kang, C S

    2014-01-01

    Development of cities has led to various environmental problems as a consequence of non sustaibale town planning. One of the strategies to make cities a livable place and to achieve low levels of CO 2 emissions (low carbon cities or LCC) is the integration of the blue and green infrastructure into the development and planning of new urban areas. Iskandar Malaysia (IM) located in the southern part of Malaysia is a special economic zone that has major urban centres. The planning of these urban centres will incorporate LCC strategies to achieve a sustainable development. The role of green (plants) and blue bodies (lakes and rivers) in moderating temperature in IM have been investigated in the current study. A remotely sensed satellite imagery was used to calculate the vegetation density and land surface temperature (LST). The effect of lakes in cooling the surrounding temperature was also investigated. Results show that increasing vegetation density by 1% can decrease the LST by 0.09°C. As for the water bodies we found as the distance increased from the lake side the temperature also increased about 1.7°C and the reduction in air humidity is 9% as the distance increased to 100 meter away from the lake

  20. Vegetation growth parameters and leaf temperature: Experimental results from a six plots green roofs' system

    International Nuclear Information System (INIS)

    Ferrante, Patrizia; La Gennusa, Maria; Peri, Giorgia; Rizzo, Gianfranco; Scaccianoce, Gianluca

    2016-01-01

    The paper provides a contribution for populating database of three physical parameters needed to model energy performance of buildings with green roofs: “coverage ratio” (σ_f), leaf area index (LAI) and leaf temperature (T_f). On purpose, six plant species were investigated experimentally: Phyla nordiflora, Aptenia lancifolia, Mesembryanthenum barbatus, Gazania nivea, Gazania uniflora, and Sedum. Proper ranges of the cited parameters have been found for each species. The here indicated ranges of σ_f values refer to different growth levels of the species in the same lapse of time, that is four months. Single measured LAI values are also reported for the same plants. As for the T_f (upper and lower layer), ranges of revealed temperatures refer to those detected from 10:30 a.m. to 16:30 p.m. of a selected day. Additionally, the dependence of T_f on climatic parameters was investigated. A linear equation resulted the best fitting curve for all experimental T_f data and the corresponding solar radiation data (with autocorrelation coefficients between 0.80 and 0.98). Furthermore, the effect potentially produced on building energy consumption by these species was analyzed using a simulation tool. Estimated cooling energy savings range approximately between 8% and 20% depending on adopted plants. - Highlights: • Green roof modeling requires the knowledge of various physical parameters. • Coverage ratio, leaf area index and leaves temperatures were measured for six species. • A tentative correlation between leaf temperature and climatic parameters was shown. • A correlation between LAI and coverage ratio was checked and discussed. • Potential effects of studied species on building energy consumption were investigated.

  1. Application of E{sub h}-pH diagram for room temperature precipitation of zinc stannate microcubes in an aqueous media

    Energy Technology Data Exchange (ETDEWEB)

    Al-Hinai, Ashraf T., E-mail: ashraf@squ.edu.om [Department of Chemistry, College of Science, Sultan Qaboos University, 123, Alkhoud (Oman); Al-Hinai, Muna H. [Department of Chemistry, College of Science, Sultan Qaboos University, 123, Alkhoud (Oman); Water Research Center, Sultan Qaboos University, 123, Alkhoud (Oman); Dutta, Joydeep, E-mail: dutta@squ.ed.om [Water Research Center, Sultan Qaboos University, 123, Alkhoud (Oman)

    2014-01-01

    Graphical abstract: - Highlights: • One pot aqueous synthesis of zinc stannate (ZnSnO{sub 3}) particles at low temperature. • Synthesis designed with the assistance of potential-pH diagram. • ZnSnO{sub 3} estimated to be stable between pH 8 and 12 was used for synthesis of the particles. • ZnSnO{sub 3}·3H{sub 2}O were formed during the precipitation of zinc stannate. - Abstract: Potential-pH diagram assisted-design for controlled precipitation is an attractive method to obtain engineered binary and ternary oxide particles. Aqueous synthesis conditions of zinc stannate (ZnSnO{sub 3}) particles at low temperature were formulated with the assistance of potential-pH diagram. The pH of a solution containing stoichiometric amounts of Zn{sup 2+} and Sn{sup 4+} was controlled for the precipitation in a one pot synthesis step at room temperature (25 °C). The effect of the concentration of the reactants on the particle size was studied by varying the concentration of the precursor (Zn{sup 2+} + Sn{sup 4+}) solution. Scanning electron micrographs show that the particles are monodispersed micron sized cubes formed by the self-organization of nano-sized crystallites. The obtained microcubes characterized by X-ray Diffraction and thermo gravimetric analysis (TGA) show that the particles are in ZnSnO{sub 3}·3H{sub 2}O form.

  2. Classifying Multi-Model Wheat Yield Impact Response Surfaces Showing Sensitivity to Temperature and Precipitation Change

    Science.gov (United States)

    Fronzek, Stefan; Pirttioja, Nina; Carter, Timothy R.; Bindi, Marco; Hoffmann, Holger; Palosuo, Taru; Ruiz-Ramos, Margarita; Tao, Fulu; Trnka, Miroslav; Acutis, Marco; hide

    2017-01-01

    Crop growth simulation models can differ greatly in their treatment of key processes and hence in their response to environmental conditions. Here, we used an ensemble of 26 process-based wheat models applied at sites across a European transect to compare their sensitivity to changes in temperature (minus 2 to plus 9 degrees Centigrade) and precipitation (minus 50 to plus 50 percent). Model results were analysed by plotting them as impact response surfaces (IRSs), classifying the IRS patterns of individual model simulations, describing these classes and analysing factors that may explain the major differences in model responses. The model ensemble was used to simulate yields of winter and spring wheat at four sites in Finland, Germany and Spain. Results were plotted as IRSs that show changes in yields relative to the baseline with respect to temperature and precipitation. IRSs of 30-year means and selected extreme years were classified using two approaches describing their pattern. The expert diagnostic approach (EDA) combines two aspects of IRS patterns: location of the maximum yield (nine classes) and strength of the yield response with respect to climate (four classes), resulting in a total of 36 combined classes defined using criteria pre-specified by experts. The statistical diagnostic approach (SDA) groups IRSs by comparing their pattern and magnitude, without attempting to interpret these features. It applies a hierarchical clustering method, grouping response patterns using a distance metric that combines the spatial correlation and Euclidian distance between IRS pairs. The two approaches were used to investigate whether different patterns of yield response could be related to different properties of the crop models, specifically their genealogy, calibration and process description. Although no single model property across a large model ensemble was found to explain the integrated yield response to temperature and precipitation perturbations, the

  3. Simulated hydrologic response to projected changes in precipitation and temperature in the Congo River basin

    Science.gov (United States)

    Aloysius, Noel; Saiers, James

    2017-08-01

    Despite their global significance, the impacts of climate change on water resources and associated ecosystem services in the Congo River basin (CRB) have been understudied. Of particular need for decision makers is the availability of spatial and temporal variability of runoff projections. Here, with the aid of a spatially explicit hydrological model forced with precipitation and temperature projections from 25 global climate models (GCMs) under two greenhouse gas emission scenarios, we explore the variability in modeled runoff in the near future (2016-2035) and mid-century (2046-2065). We find that total runoff from the CRB is projected to increase by 5 % [-9 %; 20 %] (mean - min and max - across model ensembles) over the next two decades and by 7 % [-12 %; 24 %] by mid-century. Projected changes in runoff from subwatersheds distributed within the CRB vary in magnitude and sign. Over the equatorial region and in parts of northern and southwestern CRB, most models project an overall increase in precipitation and, subsequently, runoff. A simulated decrease in precipitation leads to a decline in runoff from headwater regions located in the northeastern and southeastern CRB. Climate model selection plays an important role in future projections for both magnitude and direction of change. The multimodel ensemble approach reveals that precipitation and runoff changes under business-as-usual and avoided greenhouse gas emission scenarios (RCP8.5 vs. RCP4.5) are relatively similar in the near term but deviate in the midterm, which underscores the need for rapid action on climate change adaptation. Our assessment demonstrates the need to include uncertainties in climate model and emission scenario selection during decision-making processes related to climate change mitigation and adaptation.

  4. An evaluation of temperature and precipitation from global and regional climate models over Scandinavia

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2012-07-01

    Precipitation and temperature from global (GCMs) and regional (RCMs) climate models are compared with reanalysis and observations over Scandinavia. Also projections for the next 50-100 years are considered. The climate development is visualised as moving averages (1920-2100). Box plots are used to illuminate how well GCM runs capture the observed seasonal cycle. Maps show the seasonal difference between results from control runs (RCM) and observations (E-OBS dataset) for the reference period 1981-2000. Plots illustrate the RCM-representation of seasonal temperature and precipitations cycle for five locations in Norway and Sweden: Oslo, Bergen, Trondheim, Tromsoe and Oestersund. The results show rather large differences between control runs and observations, demonstrating the need for bias correction of results from climate models. To get an indicator of which GC M-RCM-combination give the best representation of present climate over Scandinavia, a model ranking is provided. The performance measure used is the root-mean-square deviation of mean monthly and seasonal values. The data is compared both in an area-weighted spatial average of the whole domain as well as for the selected locations. The results indicate that the regional models RACMO2 and RCA show the smallest deviations from observed climate. Among the top ranking GCM-RCM combinations, most were driven by the global model ECHAM5 and some by a version of HadCM3. These two GCMs are also present among the worst performing GCM-RCM combinations indicating that selection of RCMs is crucial. (Author)

  5. Verification of Temperature and Precipitation Simulated Data by Individual and Ensemble Performance of Five AOGCM Models for North East of Iran

    Directory of Open Access Journals (Sweden)

    B. Ashraf

    2014-08-01

    Full Text Available Scince climatic models are the basic tools to study climate change and because of the multiplicity of these models, selecting the most appropriate model for the studying location is very considerable. In this research the temperature and precipitation simulated data by BCM2, CGCM3, CNRMCM3, MRICGCM2.3 and MIROC3 models are downscaled with proportional method according A1B, A2 and B1 emission scenarios for Torbat-heydariye, Sabzevar and Mashhad initially. Then using coefficient of determination (R2, index of agreement (D and mean-square deviations (MSD, models were verified individually and as ensemble performance. The results showed that, based on individual performance and three emission scenarios, MRICGCM2.3 model in Torbat-heydariye and Mashhad and MIROC3.2 model in Sabzevar had the best performance in simulation of temperature and MIROC3.2, MRICGCM2.3 and CNRMCM3 models have provided the most accurate predictions for precipitation in Torbat-heydariye, Sabzevar and Mashahad respectively. Also simulated temperature by all models in Torbat-heydariye and Sabzevar base on B1 scenario and, in Mashhad based on A2 scenario had the lowest uncertainty. The most accuracy in modeling of precipitation was resulted based on A2 scenario in Torbat-heydariye and, B1 scenario in Sabzevar and Mashhad. Investigation of calculated statistics driven from ensemble performance of 5 selected models caused notable reduction of simulation error and thus increase the accuracy of predictions based on all emission scenarios generally. In this case, the best fitting of simulated and observed temperature data were achieved based on B1 scenario in Torbat-heydariye and Sabzevar and, A2 scenario in Mashhad. And the best fitting simulated and observed precipitation data were obtained based on A2 scenario in Torbat-heydariye and, B1 scenario in Sabzevar and Mashhad. According to the results of this research, before any climate change research it is necessary to select the

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

    Energy Technology Data Exchange (ETDEWEB)

    Williams, A.P. [Los Alamos National Laboratory, Earth and Environmental Sciences Division, Los Alamos, NM (United States); University of California, Geography Department, Santa Barbara, CA (United States); Funk, Chris [University of California, Geography Department, Santa Barbara, CA (United States); U.S. Geological Survey, Earth Resources Observation and Science (EROS), Sioux Falls, SD (United States); Michaelsen, Joel [University of California, Geography Department, Santa Barbara, CA (United States); Rauscher, Sara A. [Los Alamos National Laboratory, Theoretical Division, Los Alamos, NM (United States); Robertson, Iain; Loader, Neil J. [Swansea University, Department of Geography, College of Science, Swansea (United Kingdom); Wils, Tommy H.G. [Rotterdam University, Department of Geography, Rotterdam (Netherlands); Koprowski, Marcin [Nicolaus Copernicus University, Laboratory of Dendrochronology, Institute of Ecology and Environment Protection, Torun (Poland); Eshetu, Zewdu [Ethiopian Institute of Agricultural Research, Forestry Research Centre, Addis Ababa (Ethiopia)

    2012-11-15

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

  7. Precipitation model in microalloyed steels both isothermal and continuous cooling conditions

    International Nuclear Information System (INIS)

    Medina, S. F.; Quispe, A.; Gomez, M.

    2015-01-01

    Niobium and vanadium precipitates (nitrides and carbides) can inhibit the static recrystallization of austenite but this does not happen for Ti, which form nitrides at high temperatures. RPTT diagrams show the interaction between recrystallization and precipitation allowing study the strain induced precipitation kinetics and precipitate coarsening. Based on Dutta and Sellars expression for the start of strain-induced precipitation in microalloyed steels, a new model has been constructed which takes into account the influence of variables such as microalloying element percentages, strain, temperature, strain rate and grain size. Recrystallization- Precipitation-Time-Temperature (RPTT) diagrams have been plotted thanks to a new experimental study carried out by means of hot torsion tests on approximately twenty microalloyed steels with different Nb, V and Ti contents. Mathematical analysis of the results recommends the modification of some parameters such as the supersaturation ratio (ks) and constant B, which is no longer a constant but a function of ks. The expressions are now more consistent and predict the Precipitation-Time-Temperature (PTT) curves with remarkable accuracy. The model for strain-induced precipitation kinetics is completed by means of Avramis equation. Finally, the model constructed in isothermal testing conditions, it has been converted to continuous cooling conditions in order to apply it in hot rolling. (Author)

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

    Science.gov (United States)

    Kukal, M.; Irmak, S.

    2016-11-01

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

  9. Stable and unstable fatigue crack propagation during high temperature creep-fatigue in austenitic steels: the role of precipitation

    International Nuclear Information System (INIS)

    Lloyd, G.J.; Wareing, J.

    1979-01-01

    The distinction between stable and unstable fatigue crack propagation during high temperature creep-fatigue in austenitic stainless steels is introduced. The transition from one class of behavior to the other is related to the precipitate distribution and to the nature of the prevailing crack path. It is shown by reference to new studies and examples drawn from the literature that this behavior is common to both high strain and predominantly elastic fatigue in austenitic stainless steels. The relevance of this distinction to a mechanistic approach to high temperature plant design is discussed

  10. Climate change and precipitation: Detecting changes Climate change and precipitation: Detecting changes

    International Nuclear Information System (INIS)

    Van Boxel, John H

    2001-01-01

    Precipitation is one of the most, if not the most important climate parameter In most studies on climate change the emphasis is on temperature and sea level rise. Often too little attention is given to precipitation. For a large part this is due to the large spatial en temporal variability of precipitation, which makes the detection of changes difficult. This paper describes methods to detect changes in precipitation. In order to arrive at statistically significant changes one must use long time series and spatial averages containing the information from several stations. In the Netherlands the average yearly precipitation increased by 11% during the 20th century .In the temperate latitudes on the Northern Hemisphere (40-60QN) the average increase was about 7% over the 20th century and the globally averaged precipitation increased by about 3%. During the 20th century 38% of the land surface of the earth became wetter, 42% experienced little change (less than 5% change) and 20% became dryer. More important than the average precipitation is the occurrence of extremes. In the Netherlands there is a tendency to more extreme precipitations, whereas the occurrence of relatively dry months has not changed. Also in many other countries increases in heavy precipitation events are observed. All climate models predict a further increase of mean global precipitation if the carbon dioxide concentration doubles. Nevertheless some areas get dryer, others have little change and consequently there are also areas where the increase is much more than the global average. On a regional scale however there are large differences between the models. Climate models do not yet provide adequate information on changes in extreme precipitations

  11. A Comparison of Simple Methods to Incorporate Material Temperature Dependency in the Green's Function Method for Estimating Transient Thermal Stresses in Thick-Walled Power Plant Components.

    Science.gov (United States)

    Rouse, James; Hyde, Christopher

    2016-01-06

    The threat of thermal fatigue is an increasing concern for thermal power plant operators due to the increasing tendency to adopt "two-shifting" operating procedures. Thermal plants are likely to remain part of the energy portfolio for the foreseeable future and are under societal pressures to generate in a highly flexible and efficient manner. The Green's function method offers a flexible approach to determine reference elastic solutions for transient thermal stress problems. In order to simplify integration, it is often assumed that Green's functions (derived from finite element unit temperature step solutions) are temperature independent (this is not the case due to the temperature dependency of material parameters). The present work offers a simple method to approximate a material's temperature dependency using multiple reference unit solutions and an interpolation procedure. Thermal stress histories are predicted and compared for realistic temperature cycles using distinct techniques. The proposed interpolation method generally performs as well as (if not better) than the optimum single Green's function or the previously-suggested weighting function technique (particularly for large temperature increments). Coefficients of determination are typically above 0 . 96 , and peak stress differences between true and predicted datasets are always less than 10 MPa.

  12. Silicon isotope fractionation during silica precipitation from hot-spring waters

    Science.gov (United States)

    Geilert, Sonja; Vroon, Pieter; Keller, Nicole; Gudbrnadsson, Snorri; Stefánsson, Andri; van Bergen, Manfred

    2014-05-01

    Hot-spring systems in the Geysir geothermal area, Iceland, have been studied to explore silicon isotope fractionation in a natural setting where sinter deposits are actively formed over a temperature interval between 20° and 100° C. The SiO2(aq)concentrations in spring and stream waters range between 290 and 560ppm and stay relatively constant along downstream trajectories, irrespective of significant cooling gradients. The waters are predominantly oversaturated in amorphous silica at the temperatures measured in the field. Correlations between the saturation indices, temperature and amounts of evaporative water loss suggest that cooling and evaporation are the main causes of subaqueous silica precipitation. The δ30Si values of dissolved silica in spring water and outflowing streams average around +1o probably due to the small quantities of instantaneously precipitating silica relative to the dissolved amount. Siliceous sinters, in contrast, range between -0.1o to -4.0o consistent with a preferred incorporation of the light silicon isotope and with values for precipitated silica becoming more negative with downstream decreasing temperatures. Larger fractionation magnitudes are inversely correlated with the precipitation rate, which itself is dependent on temperature, saturation state and the extent of a system. The resulting magnitudes of solid-fluid isotopic fractionation generally decline from -3.5o at 10° C to -2.0o at 90° C. These values confirm a similar relationship between fractionation magnitude and temperature that we found in laboratory-controlled silica-precipitation experiments. However, a relatively constant offset of ca. -2.9o between field and experimental fractionation values indicates that temperature alone cannot be responsible for the observed shifts. We infer that precipitation kinetics are a prominent control of silicon isotope fractionation in aqueous environments, whereby the influence of the extent of the system on the precipitation

  13. Precipitation phase separation schemes in the Naqu River basin, eastern Tibetan plateau

    Science.gov (United States)

    Liu, Shaohua; Yan, Denghua; Qin, Tianling; Weng, Baisha; Lu, Yajing; Dong, Guoqiang; Gong, Boya

    2018-01-01

    Precipitation phase has a profound influence on the hydrological processes in the Naqu River basin, eastern Tibetan plateau. However, there are only six meteorological stations with precipitation phase (rainfall/snowfall/sleet) before 1979 within and around the basin. In order to separate snowfall from precipitation, a new separation scheme with S-shaped curve of snowfall proportion as an exponential function of daily mean temperature was developed. The determinations of critical temperatures in the single/two temperature threshold (STT/TTT2) methods were explored accordingly, and the temperature corresponding to the 50 % snowfall proportion (SP50 temperature) is an efficiently critical temperature for the STT, and two critical temperatures in TTT2 can be determined based on the exponential function and SP50 temperature. Then, different separation schemes were evaluated in separating snowfall from precipitation in the Naqu River basin. The results show that the S-shaped curve methods outperform other separation schemes. Although the STT and TTT2 slightly underestimate and overestimate the snowfall when the temperature is higher and colder than SP50 temperature respectively, the monthly and annual separation snowfalls are generally consistent with the observed snowfalls. On the whole, S-shaped curve methods, STT, and TTT2 perform well in separating snowfall from precipitation with the Pearson correlation coefficient of annual separation snowfall above 0.8 and provide possible approaches to separate the snowfall from precipitation for hydrological modelling.

  14. PRECIPITATION BEHAVIOR OF Co PHASES IN B2-ORDERED(Ni,Co)Al COMPOUND

    Institute of Scientific and Technical Information of China (English)

    W.H. Tian; A.L. Fan; M. Nemoto

    2002-01-01

    The precipitation behavior of Co phases in B2-ordered (Ni, Co)Al has been investigatedin terms of transmission electron microscopy. Fine precipitation off cc-Co occurs in(Ni, Co)Al by aging at temperature over 973K. The orientation relationship betweenthe fcc-Co precipitates and the B2-(Ni, Co)Al matrix follows the Kurdjumow-Sachs(K-S) orientation relation. But when the aging temperature is under 873K the Coprecipitates have a hcp crystal structure. The orientation relationship between thehcp-Co precipitates and the B2-(Ni, Co)Al matrix follows the Burgers orientation re-lation. (Ni, Co)Al is hardened appreciably by the fine precipitation of both the fcc-Coand hcp-Co phases. The temperature dependence of the yield strength of precipitate-containing B2-ordered (Ni, Co)Al was investigated by compression tests over the rangeof 298-1273K. The fine precipitation of Co phases enhances greatly the low and in-termediate temperature yield strength. When the deformation temperature was over873K, the strength of precipitate-containing (Ni, Co)Al is comparable to ternary dual-phase (Ni, Co)Al+Ni3Al alloy.

  15. Water quantity and quality response of a green roof to storm events: Experimental and monitoring observations.

    Science.gov (United States)

    Carpenter, Corey M G; Todorov, Dimitar; Driscoll, Charles T; Montesdeoca, Mario

    2016-11-01

    Syracuse, New York is working under a court-ordered agreement to limit combined sewer overflows (CSO) to local surface waters. Green infrastructure technologies, including green roofs, are being implemented as part of a CSO abatement strategy and to develop co-benefits of diminished stormwater runoff, including decreased loading of contaminants to the wastewater system and surface waters. The objective of this study was to examine the quantity and quality of discharge associated with precipitation events over an annual cycle from a green roof in Syracuse, NY and to compare measurements from this monitoring program with results from a roof irrigation experiment. Wet deposition, roof drainage, and water quality were measured for 87 storm events during an approximately 12 month period over 2011-2012. Water and nutrient (total phosphorus, total nitrogen, and dissolved organic carbon) mass balances were conducted on an event basis to evaluate retention annually and during the growing and non-growing seasons. These results are compared with a hydrological manipulation experiment, which comprised of artificially watering of the roof. Loadings of nutrients were calculated for experimental and actual storms using the concentration of nutrients and the flow data of water discharging the roof. The green roof was effective in retaining precipitation quantity from storm events (mean percent retention 96.8%, SD = 2.7%, n = 87), although the relative fraction of water retained decreased with increases in the size of the event. There was no difference in water retention of the green roof for the growing and non-growing seasons. Drainage waters exhibited high concentration of nutrients during the warm temperature growing season, particularly total nitrogen and dissolved organic carbon. Overall, nutrient losses were low because of the strong retention of water. However, there was marked variation in the retention of nutrients by season due to variations in concentrations in roof

  16. Factors controlling stable isotope composition of European precipitation

    International Nuclear Information System (INIS)

    Rozanski, K.; Sonntag, C.; Muennich, K.O.

    1982-01-01

    The seasonal and spatial variations of stable isotope ratios in present day European precipitation are simulated with a simple multibox model of the mean west-east horizontal transport of the atmospheric water vapour across the European continent. Isotope fractionation during the formation of precipitation leads to an increasing depletion of heavy isotopes in the residual air moisture as it moves towards the centre of the continent. This isotopic depletion is partly compensated, particularly in summer, by evapotranspiration, which is assumed to transfer soil water into the atmosphere without isotope fractionation. The model estimates are based on horizontal water vapour flux data, varying seasonally between 88 and 130 kg m -1 s -1 for the Atlantic coast region, and on the monthly precipitation, evapotranspiration and surface air temperature data available for various locations in Europe. Both continental and seasonal temperature effects observed in the stable isotope composition of European precipitation are fairly well reproduced by the model. The calculations show that the isotopic composition of local precipitation is primarily controlled by regional scale processes, i.e. by the water vapour transport patterns into the continent, and by the average precipitation-evapotranspiration history of the air masses precipitating at a given place. Local parameters such as the surface and/or cloud base temperature or the amount of precipitation modify the isotope ratios only slightly. Implications of the model predictions for the interpretation of stable isotope ratios in earlier periods as they are preserved in ice cores and in groundwater are also discussed. (Auth.)

  17. Irradiation induced precipitation in tungsten based, W-Re alloys

    Science.gov (United States)

    Williams, R. K.; Wiffen, F. W.; Bentley, J.; Stiegler, J. O.

    1983-03-01

    Tungsten-base alloys containing 5, 11, and 25 pct Re were irradiated in the EBR-II reactor. Irradiation temperatures ranged from 600 to 1500 °C. All compositions were irradiated to fluences in the range 4.3 to 6.1 X 1025 n/m2 (E > 0.1 MeV), and three 25 pct Re samples were also irradiated to 3.7 X 1026 n/m2 at temperatures 700 to 900 °C. Postirradiation examination included measurement of electrical resistivity at room temperature and lower temperatures, X-ray diffraction, optical metallography, microprobe analysis, and transmission electron microscopy. Irradiation induced resistivity decreases observed in most of the samples suggested second-phase precipitation. Complete results confirmed the precipitate formation in all samples, in disagreement with existing phase diagrams for the W-Re system. Electron diffraction showed the precipitates to be consistent with the cubic, Re-rich X-phase and inconsistent with the σ-phase. Large variations in precipitate morphology and distribution were observed between the different compositions and irradiation conditions. For the 5 and 11 pct Re-alloys, spherically symmetric strain fields surrounded the equiaxed precipitate particles, and were observed even where no particles were visible. These strain fields are believed to arise from local Re enrichment. Thermoelectric data show that the precipitation can lead to decalibration of W/Re thermocouples.

  18. Thermodynamic Calculation of Carbide Precipitate in Niobium Microalloyed Steels

    Institute of Scientific and Technical Information of China (English)

    XU Yun-bo; YU Yong-mei; LIU Xiang-hua; WANG Guo-dong

    2006-01-01

    On the basis of regular solution sublattice model, thermodynamic equilibrium of austenite/carbide in Fe-Nb-C ternary system was investigated. The equilibrium volume fraction, chemical driving force of carbide precipitates and molar fraction of niobium and carbon in solution at different temperatures were evaluated respectively. The volume fraction of precipitates increases, molar fraction of niobium dissolved in austenite decreases and molar fraction of carbon increases with decreasing the niobium content. The driving force increases with the decrease of temperature, and then comes to be stable at relatively low temperatures. The predicted ratio of carbon in precipitates is in good agreement with the measured one.

  19. Precipitation diagram of calcium carbonate polymorphs: its construction and significance

    International Nuclear Information System (INIS)

    Kawano, Jun; Shimobayashi, Norimasa; Miyake, Akira; Kitamura, Masao

    2009-01-01

    In order to interpret the formation mechanism of calcium carbonate polymorphs, we propose and construct a new 'precipitation diagram', which has two variables: the driving force for nucleation and temperature. The precipitation experiments were carried out by mixing calcium chloride and sodium carbonate aqueous solutions. As a result, a calcite-vaterite co-precipitation zone, a vaterite precipitation zone, a vaterite-aragonite co-precipitation zone and an aragonite precipitation zone can be defined. Theoretical considerations suggest that the steady state nucleation theory can explain well the appearance of these four zones, and the first-order importance of the temperature dependency of surface free energy in the nucleation of aragonite. Furthermore, the addition of an impurity will likely result in the change of these energies, and this precipitation diagram gives a new basis for interpreting the nature of the polymorphs precipitated in both inorganic and biological environments.

  20. Precipitation in a lead calcium tin anode

    International Nuclear Information System (INIS)

    Pérez-González, Francisco A.; Camurri, Carlos G.; Carrasco, Claudia A.; Colás, Rafael

    2012-01-01

    Samples from a hot rolled sheet of a tin and calcium bearing lead alloy were solution heat treated at 300 °C and cooled down to room temperature at different rates; these samples were left at room temperature to study natural precipitation of CaSn 3 particles. The samples were aged for 45 days before analysing their microstructure, which was carried out in a scanning electron microscope using secondary and backscattered electron detectors. Selected X-ray spectra analyses were conducted to verify the nature of the precipitates. Images were taken at different magnifications in both modes of observation to locate the precipitates and record their position within the images and calculate the distance between them. Differential scanning calorimeter analyses were conducted on selected samples. It was found that the mechanical properties of the material correlate with the minimum average distance between precipitates, which is related to the average cooling rate from solution heat treatment. - Highlights: ► The distance between precipitates in a lead alloy is recorded. ► The relationship between the distance and the cooling rate is established. ► It is found that the strengthening of the alloy depends on the distance between precipitates.

  1. The Effects of Temperature and Precipitation on the Yield of Zea Mays L. I the Southeastern United States

    Science.gov (United States)

    Stooksbury, David Emory

    Three families of straightforward maize (Zea mays L.) yield/climate models using monthly temperature and precipitation terms are produced. One family of models uses USDA's Crop Reporting Districts (CRD) as its scale of aggregation. The other two families of models use three different district aggregates based on climate or yield patterns. The climate and yield districts are determined by using a two-stage cluster analysis. The CRD-based family of models perform as well as the climate and yield based models. All models explain between 80% and 90% of the variance in maize yield. The most important climate term affecting maize yield in the South is the daily maximum temperature at pollination time. The higher the maximum temperature, the lower the yield. Above normal minimum temperature during pollination increases yield in the Middle South. Weather that favors early planting and rapid vegetative growth increases yield. Ideal maize yield weather includes a dry period during planting followed by a warm period during vegetative growth. Moisture variables are important only during the planting and harvest periods when above normal precipitation delays field work and thereby reduces yield. The model results indicate that the dire predictions about the fate of Southern agriculture in a trace gas warmed world may not be true. This is due to the overwhelming influence of the daily maximum temperature on yield. An optimum aggregate for climate impact studies was not found. I postulate that this is due to the dynamic nature of the American maize production system. For most climate impact studies on a dynamic agricultural system, there does not need to be a concern about the model aggregation.

  2. Precipitation Kinetics in a Nb-stabilized Ferritic Stainless Steel

    Science.gov (United States)

    Labonne, M.; Graux, A.; Cazottes, S.; Danoix, F.; Cuvilly, F.; Chassagne, F.; Perez, M.; Massardier, V.

    2017-08-01

    The precipitation occurring in a Nb-stabilized ferritic stainless steel, containing initially Nb(C, N) carbonitrides and Fe3Nb3X precipitates, was investigated during aging treatments performed between 923 K and 1163 K (650 °C and 890 °C) by combining different techniques, (thermoelectric power (TEP), scanning/transmission electron microscopy (SEM/TEM), and atom probe tomography (APT)), in order to determine the precipitation kinetics, the nature and morphology of the newly formed precipitates as well as the chemistry of the initial Fe3Nb3X precipitates, where X stands for C or N. The following composition was proposed for these precipitates: (Fe0.81 Cr0.19)3 (Nb0.85 Si0.08 Mo0.07)3 (N0.8 C0.2), highlighting the simultaneous presence of N and C in the precipitates. With regard to the precipitation in the investigated temperature range, two main phenomena, associated with a hardness decrease, were clearly identified: (i) the precipitation of Fe2Nb precipitates from the niobium initially present in solution or coming from the progressive dissolution of the Fe3Nb3X precipitates and (ii) the precipitation of the χ-phase at grain boundaries for longer aging times. From the TEP kinetics, a time-temperature-precipitation diagram has been proposed.

  3. Response of biological soil crust diazotrophs to season, altered summer precipitation and year-round increased temperature in an arid grassland of the Colorado Plateau, USA

    Directory of Open Access Journals (Sweden)

    Chris M Yeager

    2012-10-01

    Full Text Available Biological soil crusts (biocrusts, which supply significant amounts of fixed nitrogen into terrestrial ecosystems worldwide (~33 Tg y-1, are likely to respond to changes in temperature and precipitation associated with climate change. Using nifH gene-based surveys, we explored variation in the diazotrophic community of biocrusts of the Colorado Plateau, USA in response to season (autumn vs. spring, as well as field manipulations that increased the frequency of small-volume precipitation events and year-round soil temperature. Abundance of nifH genes in biocrusts ranged from 3x106 – 1x108 g-1 soil, and nifH from heterocystous cyanobacteria closely related to Scytonema hyalinum, Spirirestis rafaelensis, and Nostoc commune comprised > 98% of the total. Although there was no apparent seasonal effect on total nifH gene abundance in the biocrusts, T-RFLP analysis revealed a strong seasonal pattern in nifH composition. Spirirestis nifH abundance was estimated to oscillate 1 to >2 orders of magnitude between autumn (low and spring (high. A year-round increase of soil temperature (2 − 3 °C had little effect on the diazotroph community structure over 2 years. Altered summer precipitation had little impact on diazotroph community structure over the first 1.5 years of the study, when natural background patterns across years and seasons superseded any treatment effects. However, after the second summer of treatments, nifH abundance was 2.6 fold lower in biocrusts receiving altered precipitation. Heterocystous cyanobacteria were apparently more resilient to altered precipitation than other cyanobacteria. The results demonstrate that diazotrophic community composition of biocrusts in this semi-arid grassland undergoes strong seasonal shifts and that the abundance of its dominant members decreased in response to more frequent, small-volume precipitation events.

  4. Response of biological soil crust diazotrophs to season, altered summer precipitation, and year-round increased temperature in an arid grassland of the Colorado Plateau, USA

    Science.gov (United States)

    Yeager, Chris M.; Kuske, Cheryl R.; Carney, Travis D.; Johnson, Shannon L.; Ticknor, Lawrence O.; Belnap, Jayne

    2012-01-01

    Biological soil crusts (biocrusts), which supply significant amounts of fixed nitrogen into terrestrial ecosystems worldwide (~33Tg y-1), are likely to respond to changes in temperature and precipitation associated with climate change. Using nifH gene-based surveys, we explored variation in the diazotrophic community of biocrusts of the Colorado Plateau, USA in response to season (autumn vs. spring), as well as field manipulations that increased the frequency of small volume precipitation events and year-round soil temperature. Abundance of nifH genes in biocrusts ranged from 3×106 to 1×8 g-1 soil, and nifH from heterocystous cyanobacteria closely related to Scytonema hyalinum, Spirirestis rafaelensis, and Nostoc commune comprised >98% of the total. Although there was no apparent seasonal effect on total nifH gene abundance in the biocrusts, T-RFLP analysis revealed a strong seasonal pattern in nifH composition. Spirirestis nifH abundance was estimated to oscillate 1 to >2 orders of magnitude between autumn (low) and spring (high). A year-round increase of soil temperature (2–3°C) had little effect on the diazotroph community structure over 2 years. Altered summer precipitation had little impact on diazotroph community structure over the first 1.5years of the study, when natural background patterns across years and seasons superseded any treatment effects. However, after the second summer of treatments, nifH abundance was 2.6-fold lower in biocrusts receiving altered precipitation. Heterocystous cyanobacteria were apparently more resilient to altered precipitation than other cyanobacteria. The results demonstrate that diazotrophic community composition of biocrusts in this semi-arid grassland undergoes strong seasonal shifts and that the abundance of its dominant members decreased in response to more frequent, small volume precipitation events.

  5. Increased temperature and altered summer precipitation have differential effects on biological soil crusts in a dryland ecosystem

    Science.gov (United States)

    Johnson, Shannon L.; Kuske, Cheryl R.; Carney, Travis D.; Housman, David C.; Gallegos-Graves, La Verne; Belnap, Jayne

    2012-01-01

    Biological soil crusts (biocrusts) are common and ecologically important members of dryland ecosystems worldwide, where they stabilize soil surfaces and contribute newly fixed C and N to soils. To test the impacts of predicted climate change scenarios on biocrusts in a dryland ecosystem, the effects of a 2–3 °C increase in soil temperature and an increased frequency of smaller summer precipitation events were examined in a large, replicated field study conducted in the cold desert of the Colorado Plateau, USA. Surface soil biomass (DNA concentration), photosynthetically active cyanobacterial biomass (chlorophyll a concentration), cyanobacterial abundance (quantitative PCR assay), and bacterial community composition (16S rRNA gene sequencing) were monitored seasonally over 2 years. Soil microbial biomass and bacterial community composition were highly stratified between the 0–2 cm depth biocrusts and 5–10 cm depth soil beneath the biocrusts. The increase in temperature did not have a detectable effect on any of the measured parameters over 2 years. However, after the second summer of altered summer precipitation pattern, significant declines occurred in the surface soil biomass (avg. DNA concentration declined 38%), photosynthetic cyanobacterial biomass (avg. chlorophyll a concentration declined 78%), cyanobacterial abundance (avg. gene copies g−1 soil declined 95%), and proportion of Cyanobacteria in the biocrust bacterial community (avg. representation in sequence libraries declined 85%). Biocrusts are important contributors to soil stability, soil C and N stores, and plant performance, and the loss or reduction of biocrusts under an altered precipitation pattern associated with climate change could contribute significantly to lower soil fertility and increased erosion and dust production in dryland ecosystems at a regional scale.

  6. Association between Precipitation and Diarrheal Disease in Mozambique.

    Science.gov (United States)

    Horn, Lindsay M; Hajat, Anjum; Sheppard, Lianne; Quinn, Colin; Colborn, James; Zermoglio, Maria Fernanda; Gudo, Eduardo S; Marrufo, Tatiana; Ebi, Kristie L

    2018-04-10

    Diarrheal diseases are a leading cause of morbidity and mortality in Africa. Although research documents the magnitude and pattern of diarrheal diseases are associated with weather in particular locations, there is limited quantification of this association in sub-Saharan Africa and no studies conducted in Mozambique. Our study aimed to determine whether variation in diarrheal disease was associated with precipitation in Mozambique. In secondary analyses we investigated the associations between temperature and diarrheal disease. We obtained weekly time series data for weather and diarrheal disease aggregated at the administrative district level for 1997-2014. Weather data include modeled estimates of precipitation and temperature. Diarrheal disease counts are confirmed clinical episodes reported to the Mozambique Ministry of Health ( n = 7,315,738). We estimated the association between disease counts and precipitation, defined as the number of wet days (precipitation > 1 mm) per week, for the entire country and for Mozambique's four regions. We conducted time series regression analyses using an unconstrained distributed lag Poisson model adjusted for time, maximum temperature, and district. Temperature was similarly estimated with adjusted covariates. Using a four-week lag, chosen a priori, precipitation was associated with diarrheal disease. One additional wet day per week was associated with a 1.86% (95% CI: 1.05-2.67%), 1.37% (95% CI: 0.70-2.04%), 2.09% (95% CI: 1.01-3.18%), and 0.63% (95% CI: 0.11-1.14%) increase in diarrheal disease in Mozambique's northern, central, southern, and coastal regions, respectively. Our study indicates a strong association between diarrheal disease and precipitation. Diarrheal disease prevention efforts should target areas forecast to experience increased rainfall. The burden of diarrheal disease may increase with increased precipitation associated with climate change, unless additional health system interventions are undertaken.

  7. Simulated hydrologic response to projected changes in precipitation and temperature in the Congo River basin

    Directory of Open Access Journals (Sweden)

    N. Aloysius

    2017-08-01

    Full Text Available Despite their global significance, the impacts of climate change on water resources and associated ecosystem services in the Congo River basin (CRB have been understudied. Of particular need for decision makers is the availability of spatial and temporal variability of runoff projections. Here, with the aid of a spatially explicit hydrological model forced with precipitation and temperature projections from 25 global climate models (GCMs under two greenhouse gas emission scenarios, we explore the variability in modeled runoff in the near future (2016–2035 and mid-century (2046–2065. We find that total runoff from the CRB is projected to increase by 5 % [−9 %; 20 %] (mean – min and max – across model ensembles over the next two decades and by 7 % [−12 %; 24 %] by mid-century. Projected changes in runoff from subwatersheds distributed within the CRB vary in magnitude and sign. Over the equatorial region and in parts of northern and southwestern CRB, most models project an overall increase in precipitation and, subsequently, runoff. A simulated decrease in precipitation leads to a decline in runoff from headwater regions located in the northeastern and southeastern CRB. Climate model selection plays an important role in future projections for both magnitude and direction of change. The multimodel ensemble approach reveals that precipitation and runoff changes under business-as-usual and avoided greenhouse gas emission scenarios (RCP8.5 vs. RCP4.5 are relatively similar in the near term but deviate in the midterm, which underscores the need for rapid action on climate change adaptation. Our assessment demonstrates the need to include uncertainties in climate model and emission scenario selection during decision-making processes related to climate change mitigation and adaptation.

  8. Retrofitted green roofs and walls and improvements in thermal comfort

    Science.gov (United States)

    Feitosa, Renato Castiglia; Wilkinson, Sara

    2017-06-01

    Increased urbanization has led to a worsening in the quality of life for many people living in large cities in respect of the urban heat island effect and increases of indoor temperatures in housing and other buildings. A solution may be to retrofit existing environments to their former conditions, with a combination of green infrastructures applied to existing walls and rooftops. Retrofitted green roofs may attenuate housing temperature. However, with tall buildings, facade areas are much larger compared to rooftop areas, the role of green walls in mitigating extreme temperatures is more pronounced. Thus, the combination of green roofs and green walls is expected to promote a better thermal performance in the building envelope. For this purpose, a modular vegetated system is adopted for covering both walls and rooftops. Rather than temperature itself, the heat index, which comprises the combined effect of temperature and relative humidity is used in the evaluation of thermal comfort in small scale experiments performed in Sydney - Australia, where identical timber framed structures prototypes (vegetated and non-vegetated) are compared. The results have shown a different understanding of thermal comfort improvement regarding heat index rather than temperature itself. The combination of green roof and walls has a valid role to play in heat index attenuation.

  9. Kinetics of radiation-induced precipitation at the alloy surface

    Science.gov (United States)

    Lam, N. Q.; Nguyen, T.; Leaf, G. K.; Yip, S.

    1988-05-01

    Radiation-induced precipitation of a new phase at the surface of an alloy during irradiation at elevated temperatures was studied with the aid of a kinetic model of segregation. The preferential coupling of solute atoms with the defect fluxes gives rise to a strong solute enrichment at the surface, which, if surpassing the solute solubility limit, leads to the formation of a precipitate layer. The moving precipitate/matrix interface was accommodated by means of a mathematical scheme that transforms spatial coordinates into a reference frame in which the boundaries are immobile. Sample calculations were performed for precipitation of the γ'-Ni 3Si layer on Ni-Si alloys undergoing electron irradiation. The dependences of the precipitation kinetics on the defect-production rate, irradiation temperature, internal defect sink concentration and alloy composition were investigated systematically.

  10. Growth of filamentous blue-green algae at high temperatures: a source of biomass for renewable fuels

    Energy Technology Data Exchange (ETDEWEB)

    Timourian, H.; Ward, R.L.; Jeffries, T.W.

    1977-08-17

    The growth of filamentous blue-green algae (FBGA) at high temperatures in outdoor, shallow solar ponds is being investigated. The temperature of the 60-m/sup 2/ ponds can be controlled to an average temperature of 45/sup 0/C. The growth of FBGA at high temperatures offers an opportunity, not presently available from outdoor algal ponds or energy farms, to obtain large amounts of biomass. Growth of algae at high temperatures results in higher yields because of increased growth rate, the higher light intensity that can be used before saturating the photosynthetic process, easier maintenance of selected FBGA strains, and fewer predators to decimate culture. Additional advantages of growing FBGA as a source of biomass include: bypassing the limitations of nutrient sources, because FBGA fix their own nitrogen and require only CO/sub 2/ when inorganic nutrients are recycled; toleration of higher salinity and metal ion concentrations; and easier and less expensive harvesting procedures.

  11. Towards green loyalty: the influences of green perceived risk, green image, green trust and green satisfaction

    Science.gov (United States)

    Chrisjatmiko, K.

    2018-01-01

    The paper aims to present a comprehensive framework for the influences of green perceived risk, green image, green trust and green satisfaction to green loyalty. The paper also seeks to account explicitly for the differences in green perceived risk, green image, green trust, green satisfaction and green loyalty found among green products customers. Data were obtained from 155 green products customers. Structural equation modeling was used in order to test the proposed hypotheses. The findings show that green image, green trust and green satisfaction has positive effects to green loyalty. But green perceived risk has negative effects to green image, green trust and green satisfaction. However, green perceived risk, green image, green trust and green satisfaction also seems to be a good device to gain green products customers from competitors. The contributions of the paper are, firstly, a more complete framework of the influences of green perceived risk, green image, green trust and green satisfaction to green loyalty analyses simultaneously. Secondly, the study allows a direct comparison of the difference in green perceived risk, green image, green trust, green satisfaction and green loyalty between green products customers.

  12. Short-Term Impacts of the Air Temperature on Greening and Senescence in Alaskan Arctic Plant Tundra Habitats

    Directory of Open Access Journals (Sweden)

    Jeremy L. May

    2017-12-01

    Full Text Available Climate change is warming the temperatures and lengthening the Arctic growing season with potentially important effects on plant phenology. The ability of plant species to acclimate to changing climatic conditions will dictate the level to which their spatial coverage and habitat-type dominance is different in the future. While the effect of changes in temperature on phenology and species composition have been observed at the plot and at the regional scale, a systematic assessment at medium spatial scales using new noninvasive sensor techniques has not been performed yet. At four sites across the North Slope of Alaska, changes in the Normalized Difference Vegetation Index (NDVI signal were observed by Mobile Instrumented Sensor Platforms (MISP that are suspended over 50 m transects spanning local moisture gradients. The rates of greening (measured in June and senescence (measured in August in response to the air temperature was estimated by changes in NDVI measured as the difference between the NDVI on a specific date and three days later. In June, graminoid- and shrub-dominated habitats showed the greatest rates of NDVI increase in response to the high air temperatures, while forb- and lichen-dominated habitats were less responsive. In August, the NDVI was more responsive to variations in the daily average temperature than spring greening at all sites. For graminoid- and shrub-dominated habitats, we observed a delayed decrease of the NDVI, reflecting a prolonged growing season, in response to high August temperatures. Consequently, the annual C assimilation capacity of these habitats is increased, which in turn may be partially responsible for shrub expansion and further increases in net summer CO2 fixation. Strong interannual differences highlight that long-term and noninvasive measurements of such complex feedback mechanisms in arctic ecosystems are critical to fully articulate the net effects of climate variability and climate change on

  13. Electron precipitation in the morning sector of the auroral zone

    International Nuclear Information System (INIS)

    Jentsch, V.

    1976-01-01

    Auroral electron precipitation in the morning sector is assumed to be the result of an electromagnetic cyclotron instability of a particle distribution that evolves adiabatically as its constituent electrons drift eastward from a source near midnight. The adiabatic distribution is calculated by using Green's function in various magnetospheric field models, and the corresponding growth rates for whistler mode waves are calculated by the method of Kennel and Petschek (1966). The region of maximum calculated wave growth corresponds spatially and temporally to the region of maximum observed electron precipitation only when the magnetospheric electric field is included realistically in the model

  14. Climatological Modeling of Monthly Air Temperature and Precipitation in Egypt through GIS Techniques

    Science.gov (United States)

    El Kenawy, A.

    2009-09-01

    This paper describes a method for modeling and mapping four climatic variables (maximum temperature, minimum temperature, mean temperature and total precipitation) in Egypt using a multiple regression approach implemented in a GIS environment. In this model, a set of variables including latitude, longitude, elevation within a distance of 5, 10 and 15 km, slope, aspect, distance to the Mediterranean Sea, distance to the Red Sea, distance to the Nile, ratio between land and water masses within a radius of 5, 10, 15 km, the Normalized Difference Vegetation Index (NDVI), the Normalized Difference Water Index (NDWI), the Normalized Difference Temperature Index (NDTI) and reflectance are included as independent variables. These variables were integrated as raster layers in MiraMon software at a spatial resolution of 1 km. Climatic variables were considered as dependent variables and averaged from quality controlled and homogenized 39 series distributing across the entire country during the period of (1957-2006). For each climatic variable, digital and objective maps were finally obtained using the multiple regression coefficients at monthly, seasonal and annual timescale. The accuracy of these maps were assessed through cross-validation between predicted and observed values using a set of statistics including coefficient of determination (R2), root mean square error (RMSE), mean absolute error (MAE), mean bias Error (MBE) and D Willmott statistic. These maps are valuable in the sense of spatial resolution as well as the number of observatories involved in the current analysis.

  15. Green synthesis of Ni-Nb oxide catalysts for low-temperature oxidative dehydrogenation of ethane

    KAUST Repository

    Zhu, Haibo

    2015-03-05

    The straightforward solid-state grinding of a mixture of Ni nitrate and Nb oxalate crystals led to, after mild calcination (T<400°C), nanostructured Ni-Nb oxide composites. These new materials efficiently catalyzed the oxidative dehydrogenation (ODH) of ethane to ethylene at a relatively low temperature (T<300°C). These catalysts appear to be much more stable than the corresponding composites prepared by other chemical methods; more than 90% of their original intrinsic activity was retained after 50h with time on-stream. Furthermore, the stability was much less affected by the Nb content than in composites prepared by classical "wet" syntheses. These materials, obtained in a solvent-free way, are thus promising green and sustainable alternatives to the current Ni-Nb candidates for the low-temperature ODH of ethane.

  16. Co-precipitation synthesis and luminescence behavior of Ce-doped yttrium aluminum garnet (YAG:Ce) phosphor: The effect of precipitant

    International Nuclear Information System (INIS)

    Zhang Kai; Liu Hezhou; Wu Yating; Hu Wenbin

    2008-01-01

    YAG:Ce precursors were co-precipitated using ammonia water and ammonium hydrogen carbonate as precipitants, respectively. Phase transition of the precursors during sintering was compared between the two precipitants. The precursors synthesized with ammonia water transformed to YAG at about 1000 deg. C via YAlO 3 phase. The precursors synthesized with ammonium hydrogen carbonate directly converted to pure YAG at about 900 deg. C. Comparing the powders produced with the two precipitants, the powders produced with ammonia hydrogen carbonate showed good dispersity. When sintered at 1600 deg. C, aggregation of the powders synthesized with the two precipitants both became severe. With increase the sintering temperature, the maximum wavelength of excitation and emission spectra of the phosphors synthesized with ammonium water hardly varied. While the maximum wavelength of excitation spectra of the phosphors synthesized with ammonium hydrogen carbonate unchanged, and the emission spectra showed red shift. Because of size effect and higher loss of cerium content, the emission intensity of phosphors prepared with ammonium hydrogen carbonate was lower than the phosphors prepared with ammonium water, when sintered at the same temperature

  17. The influence of green microstructure and sintering parameters on precipitation process during copper-nickel-zinc ferrites sintering

    Directory of Open Access Journals (Sweden)

    Barba, Antonio

    2014-04-01

    Full Text Available Microstructural changes that occur during heat treatment of copper-nickel-zinc ferrites have been studied. The process of precipitation of the two types of crystals that occur during the sintering process has been analyzed. It is found that this process depends on dry relative density of the press specimens and on the following sintering parameters: sintering temperature, sintering time and cooling rate of the thermal cycle. Crystal precipitates characterization have been done by scanning electron microscopy (SEM, energy-dispersive X-ray (EDX analysis, X-ray diffraction (XRD, and X-ray photoelectron spectroscopy (XPS. These techniques have allowed to determine the nature of these crystals, which in this case correspond to zinc and copper oxides. It has been used two chemical reactions to explain the bulk precipitation and subsequent re-dissolution of these crystal precipitates during sintering.En este trabajo se han estudiado los cambios microestructurales que se producen durante el tratamiento térmico de las ferritas de cobre-níquel-cinc y se ha analizado el proceso de precipitación de los dos tipos de cristales que aparecen durante el proceso de sinterización. Se ha encontrado que este proceso depende de la densidad relativa en seco de las muestras compactadas y de las siguientes variables de la etapa de sinterización: temperatura y tiempo de sinterización y velocidad de enfriamiento. La caracterización de los cristales precipitados se ha realizado por microscopía electrónica de barrido (MEB, microanálisis por dispersión de energía de rayos X (EDX, difracción de rayos X (DRX, y espectroscopía de fotoelectrones de rayos X (XPS. Estas técnicas han permitido determinar la naturaleza de estos cristales, que en este caso corresponden a los óxidos de cinc y de cobre. Se han propuesto dos reacciones químicas que permiten explicar el proceso de precipitación y la posterior re-disolución de estos cristales precipitados durante la

  18. Analysis of climatic variations in seasonal precipitation and temperature in Salamanca (Spain); Analisis de las variaciones climaticas en series estacionales de temperatura y precipitacion en Salamanca (Espana)

    Energy Technology Data Exchange (ETDEWEB)

    Garcia Casado, A.; Encinas, A.H.; Rodriguez Puebla, C. [Dpto. de Fisica General y de la Atmosfera Universidad de Salamanca, Salamanca (Spain)

    1996-12-31

    This paper describes the seasonal precipitation and temperature variability in Salamanca. The objectives of the study are: to determine the climate signals on inter annual time-scale within the time series; to redefine the series as a function of the significant oscillation components and to predict local precipitation and temperature variables. The methods used are spectral analysis to obtain the periods of the significant components, linear and nonlinear regression models to obtain the analytical functions that best fit the data. (Author) 14 refs.

  19. How Do Tropical Sea Surface Temperatures Influence the Seasonal Distribution of Precipitation in the Equatorial Amazon?.

    Science.gov (United States)

    Fu, Rong; Dickinson, Robert E.; Chen, Mingxuan; Wang, Hui

    2001-10-01

    Although the correlation between precipitation over tropical South America and sea surface temperatures (SSTs) over the Pacific and Atlantic has been documented since the early twentieth century, the impact of each ocean on the timing and intensity of the wet season over tropical South America and the underlying mechanisms have remained unclear. Numerical experiments have been conducted using the National Center for Atmospheric Research Community Climate Model Version 3 to explore these impacts. The results suggest the following.1)Seasonality of SSTs in the tropical Pacific and Atlantic has an important influence on precipitation in the eastern Amazon during the equinox seasons. The eastern side of the Amazon is influenced both by the direct thermal circulation of the Atlantic intertropical convergence zone (ITCZ) and by Rossby waves. These processes are enhanced by the seasonal cycles of SSTs in the tropical Atlantic and Pacific. SSTs affect Amazon precipitation much less during the solstice seasons and in the western Amazon.2)The seasonality of SSTs in the Atlantic more strongly affects Amazon rainfall than does that of the Pacific. Without the former, austral spring in the eastern equatorial Amazon would be a wet season, rather than the observed dry season. As a consequence of the lag at that time of the southward seasonal migration of the Atlantic SSTs behind that of the insolation, the Atlantic ITCZ centers itself near 10°N, instead of at the equator, imposing subsidence and low-level anticyclonic flow over the eastern equatorial Amazon, thus drying the air above the planetary boundary layer and reducing the low-level moisture convergence. Consequently, convection in the eastern Amazon is suppressed despite strong surface heating.3)Seasonality of the SSTs in the tropical Pacific also tends to reduce precipitation in the eastern Amazon during both spring and fall. In spring, subsidence is enhanced not only through a zonal direct circulation, but also through

  20. 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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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

  2. Reconstructed Temperature And Precipitation On A Millennial Timescale From Tree-Rings In The Southern Colorado Plateau, U.S.A.

    Energy Technology Data Exchange (ETDEWEB)

    Salzer, M.W. [Laboratory of Tree-Ring Research, The University of Arizona, Tucson, Arizona, 85721 (United States); Kipfmueller, K.F. [Department of Geography, University of Minnesota, Minneapolis, MN, 55455 (United States)

    2005-06-01

    Two independent calibrated and verified climate reconstructions from ecologically contrasting tree-ring sites in the southern Colorado Plateau, U.S.A. reveal decadal-scale climatic trends during the past two millennia. Combining precisely dated annual mean-maximum temperature and October through July precipitation reconstructions yields an unparalleled record of climatic variability. The approach allows for the identification of thirty extreme wet periods and thirty-five extreme dry periods in the 1,425-year precipitation reconstruction and 30 extreme cool periods and 26 extreme warm periods in 2,262-year temperature reconstruction. In addition, the reconstructions were integrated to identify intervals when conditions were extreme in both climatic variables (cool/dry, cool/wet, warm/dry, warm/wet). Noteworthy in the reconstructions are the post-1976 warm/wet period, unprecedented in the 1,425-year record both in amplitude and duration, anomalous and prolonged late 20th century warmth, that while never exceeded, was nearly equaled in magnitude for brief intervals in the past, and substantial decadal-scale variability within the Medieval Warm Period and Little Ice Age intervals.

  3. Precipitation in a lead calcium tin anode

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Gonzalez, Francisco A., E-mail: fco.aurelio@inbox.com [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon (Mexico); Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia, Universidad Autonoma de Nuevo Leon (Mexico); Camurri, Carlos G., E-mail: ccamurri@udec.cl [Departamento de Ingenieria de Materiales, Universidad de Concepcion (Chile); Carrasco, Claudia A., E-mail: ccarrascoc@udec.cl [Departamento de Ingenieria de Materiales, Universidad de Concepcion (Chile); Colas, Rafael, E-mail: rafael.colas@uanl.edu.mx [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon (Mexico); Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia, Universidad Autonoma de Nuevo Leon (Mexico)

    2012-02-15

    Samples from a hot rolled sheet of a tin and calcium bearing lead alloy were solution heat treated at 300 Degree-Sign C and cooled down to room temperature at different rates; these samples were left at room temperature to study natural precipitation of CaSn{sub 3} particles. The samples were aged for 45 days before analysing their microstructure, which was carried out in a scanning electron microscope using secondary and backscattered electron detectors. Selected X-ray spectra analyses were conducted to verify the nature of the precipitates. Images were taken at different magnifications in both modes of observation to locate the precipitates and record their position within the images and calculate the distance between them. Differential scanning calorimeter analyses were conducted on selected samples. It was found that the mechanical properties of the material correlate with the minimum average distance between precipitates, which is related to the average cooling rate from solution heat treatment. - Highlights: Black-Right-Pointing-Pointer The distance between precipitates in a lead alloy is recorded. Black-Right-Pointing-Pointer The relationship between the distance and the cooling rate is established. Black-Right-Pointing-Pointer It is found that the strengthening of the alloy depends on the distance between precipitates.

  4. Upconversion emission study of Er3+/Yb3+ doped barium titanate phosphor prepared by co-precipitation method

    International Nuclear Information System (INIS)

    Mahata, M.K.; Dey, R.; Kumar, K.; Rai, V.K.; Rai, S.B.

    2012-01-01

    In the present work we have successfully synthesized the Er 3+ , Yb 3+ doped barium titanate phosphor via co-precipitation synthesis method. Under 980 nm excitation, tri-color upconversion fluorescence has been observed. The Fourier Transform Infrared measurement was done to check the presence of organic impurities. In order to find out how many photons are involved in each emission band, the variation of UC emission intensity of the codoped phosphor is studied with increase in excitation power. Upconversion emission spectra show that as the annealing temperature of the powder is increased, intensity of red emission decreases and intensity of green emission increases due to the decrease in maximum phonon frequency of the host material. (author)

  5. Impacts of interactive dust and its direct radiative forcing on interannual variations of temperature and precipitation in winter over East Asia: Impacts of Dust on IAVs of Temperature

    Energy Technology Data Exchange (ETDEWEB)

    Lou, Sijia [Scripps Institution of Oceanography, University of California, San Diego, La Jolla California USA; Atmospheric Science and Global Change Division, Pacific Northwest National Laboratory, Richland Washington USA; Russell, Lynn M. [Scripps Institution of Oceanography, University of California, San Diego, La Jolla California USA; Yang, Yang [Scripps Institution of Oceanography, University of California, San Diego, La Jolla California USA; Atmospheric Science and Global Change Division, Pacific Northwest National Laboratory, Richland Washington USA; Liu, Ying [Atmospheric Science and Global Change Division, Pacific Northwest National Laboratory, Richland Washington USA; Singh, Balwinder [Atmospheric Science and Global Change Division, Pacific Northwest National Laboratory, Richland Washington USA; Ghan, Steven J. [Atmospheric Science and Global Change Division, Pacific Northwest National Laboratory, Richland Washington USA

    2017-08-24

    We used 150-year pre-industrial simulations of the Community Earth System Model (CESM) to quantify the impacts of interactively-modeled dust emissions on the interannual variations of temperature and precipitation over East Asia during the East Asian Winter Monsoon (EAWM) season. The simulated December-January-February dust column burden and dust optical depth are lower over northern China in the strongest EAWM years than those of the weakest years, with regional mean values lower by 38.3% and 37.2%, respectively. The decrease in dust over the dust source regions (the Taklamakan and Gobi Deserts) and the downwind region (such as the North China Plain) leads to an increase in direct radiative forcing (RF) both at the surface and top of atmosphere by up to 1.5 and 0.75 W m-2, respectively. The effects of EAWM-related variations in surface winds, precipitation and their effects on dust emissions and wet removal contribute about 67% to the total dust-induced variations of direct RF at the surface and partly offset the cooling that occurs with the EAWM strengthening by heating the surface. The variations of surface air temperature induced by the changes in wind and dust emissions increase by 0.4-0.6 K over eastern coastal China, northeastern China, and Japan, which weakens the impact of EAWM on surface air temperature by 3–18% in these regions. The warming results from the combined effects of changes in direct RF and easterly wind anomalies that bring warm air from the ocean to these regions. Moreover, the feedback of the changes in wind on dust emissions weakens the variations of the sea level pressure gradient on the Siberian High while enhancing the Maritime Continent Low. Therefore, cold air is prevented from being transported from Siberia, Kazakhstan, western and central China to the western Pacific Ocean and decreases surface air temperature by 0.6 K and 2 K over central China and the Tibetan Plateau, respectively. Over eastern coastal China, the variations of

  6. The Effect of Surface Preparation on the Precipitation of Sigma During High Temperature Exposure of S32205 Duplex Stainless Steel

    Science.gov (United States)

    Jepson, Mark A. E.; Rowlett, Matthew; Higginson, Rebecca L.

    2017-03-01

    Although the formation of sigma phase in duplex stainless steels is reasonably well documented, the effect of surface finish on its formation rate in surface regions has not been previously noted. The growth of the sigma phase precipitated in the subsurface region (to a maximum depth of 120 μm) has been quantified after heat treatment of S32205 duplex stainless steel at 1073 K (800 °C) and 1173 K (900 °C) after preparation to two surface finishes. Here, results are presented that show that there is a change in the rate of sigma phase formation in the surface region of the material, with a coarser surface finish leading to a greater depth of precipitation at a given time and temperature of heat treatment. The growth rate and morphology of the precipitated sigma has been examined and explored in conjunction with thermodynamic equilibrium phase calculations.

  7. Covariability of seasonal temperature and precipitation over the Iberian Peninsula in high-resolution regional climate simulations (1001-2099)

    Science.gov (United States)

    Fernández-Montes, S.; Gómez-Navarro, J. J.; Rodrigo, F. S.; García-Valero, J. A.; Montávez, J. P.

    2017-04-01

    Precipitation and surface temperature are interdependent variables, both as a response to atmospheric dynamics and due to intrinsic thermodynamic relationships and feedbacks between them. This study analyzes the covariability of seasonal temperature (T) and precipitation (P) across the Iberian Peninsula (IP) using regional climate paleosimulations for the period 1001-1990, driven by reconstructions of external forcings. Future climate (1990-2099) was simulated according to SRES scenarios A2 and B2. These simulations enable exploring, at high spatial resolution, robust and physically consistent relationships. In winter, positive P-T correlations dominate west-central IP (Pearson correlation coefficient ρ = + 0.43, for 1001-1990), due to prevalent cold-dry and warm-wet conditions, while this relationship weakens and become negative towards mountainous, northern and eastern regions. In autumn, negative correlations appear in similar regions as in winter, whereas for summer they extend also to the N/NW of the IP. In spring, the whole IP depicts significant negative correlations, strongest for eastern regions (ρ = - 0.51). This is due to prevalent frequency of warm-dry and cold-wet modes in these regions and seasons. At the temporal scale, regional correlation series between seasonal anomalies of temperature and precipitation (assessed in 31 years running windows in 1001-1990) show very large multidecadal variability. For winter and spring, periodicities of about 50-60 years arise. The frequency of warm-dry and cold-wet modes appears correlated with the North Atlantic Oscillation (NAO), explaining mainly co-variability changes in spring. For winter and some regions in autumn, maximum and minimum P-T correlations appear in periods with enhanced meridional or easterly circulation (low or high pressure anomalies in the Mediterranean and Europe). In spring and summer, the Atlantic Multidecadal Oscillation shows some fingerprint on the frequency of warm/cold modes. For

  8. Thermal Study on Extensive Green Roof Integrated Irrigation in Northwestern Arid Regions of China

    Directory of Open Access Journals (Sweden)

    Yajun Wang

    2017-11-01

    Full Text Available Selection of xerophils and drought tolerant plants is highly crucial in green roof techniques in the drought prone regions of Northwest China. In this study, the thermal performance under the natural conventional climate in summer was analyzed using a self-made simulation experimental platform through comparison of the internal surface temperature with and without green roofs. The distribution frequency of internal surface temperature was investigated by dividing internal surface temperature into several ranges. Statistical analysis showed that the frequency of internal surface temperature lower than 33 °C for green roofs was 91.8%, about 1.09 times higher than that for non-green roofs, and that the sum of internal surface temperature exceeding 35 °C was about one third of that for non-green roofs. The results proved that green roofs have a significant insulation effect. Moreover, the thermal insulation property of green roofs had a strong positive relation with outside temperature. The thermal insulation characteristic was improved as the outdoor temperature increased, additionally, it had a better insulation effect within two hours after irrigation.

  9. Multi-scale monitoring of a remarkable green roof: the Green Wave of Champs-sur-Marne

    Science.gov (United States)

    Stanic, Filip; Versini, Pierre-Antoine; Schertzer, Daniel; Delage, Pierre; Tchiguirinskaia, Ioulia; Cui, Yu-Jun; Baudoin, Genevieve

    2017-04-01

    The installation of green infrastructures on existing or new roofs has become very popular in recent years (more than 2 km2 of green roofs is implemented each year in France) for many reasons. Among all of the green roofs' advantages, those related to storm water management are often pushed forward, since it has been pointed out that urban runoff peak can be significantly reduced and delayed thanks to the green roofs' retention and detention capabilities. Microclimate can also be affected by decreasing the temperature in the surrounding green area. However, dynamic physical processes involved in green roofs are highly non linear and variable. In order to accurately assess their performances, detailed monitoring experiments are required, both in situ and in the lab, so as to better understand the thermo-hydric behaviour of green roofs and to capture the related spatio-temporal variability at different scales. Based on these considerations, the 1 ha area wavy-form green roof of a section of the Bienvenüe building, called the Green Wave, is currently being monitored in Champs-sur-Marne (France), in front of Ecole des Ponts ParisTech. Initiated in the "Blue Green Dream" European project, detailed measurements systems have been implemented for studying all components of the water balance. Among others, a wireless network of water content and temperature sensors has been especially installed for characterizing spatial and temporal variability of infiltration, retention and evapotranspiration processes. In parallel, some laboratory tests have been conducted to better characterize the hydro-mechanical properties of the substrate. Moreover, at the Green Wave scale, some discharge measurements are carried out in the storm-water pipes that are collecting drained water, to determine runoff flow. This talk will present the current monitoring campaigns and analyze the data collected in the Universal Multifractal framework. This work represents the initial stage for developing a

  10. Study of the precipitation-recrystallization interaction in a vanadium micro alloyed steel with 0.35 % C

    International Nuclear Information System (INIS)

    Quispe, A.B.; Medina, S.F.; Cabrera, J.M.; Prado, J.M.

    1998-01-01

    A method is described which allows to study the interaction recrystallization-induced precipitation by the deformation of vanadium micro alloyed steel and 0.35% C. By means of torsion tests and applying the Back Extrapolation method, the recrystallized fraction at different temperatures has been determined. When the precipitation begins, the recrystallized fraction does not follow the Avrami's equation. This allows to know the instant when precipitation starts (P s ) and the instant when precipitation finishes (P f ). Therefore, Recrystallization-Precipitation-Time-Temperature (RPTT) diagrams can be obtained, which graphically show the interaction Recrystallization-Precipitation and simultaneously allows the determination of the static recrystallization critical temperature (SRCT). This temperature represents the limit between the two phases, before and after precipitation. (Author) 10 refs

  11. Precipitation Indices Low Countries

    Science.gov (United States)

    van Engelen, A. F. V.; Ynsen, F.; Buisman, J.; van der Schrier, G.

    2009-09-01

    Since 1995, KNMI published a series of books(1), presenting an annual reconstruction of weather and climate in the Low Countries, covering the period AD 763-present, or roughly, the last millennium. The reconstructions are based on the interpretation of documentary sources predominantly and comparison with other proxies and instrumental observations. The series also comprises a number of classifications. Amongst them annual classifications for winter and summer temperature and for winter and summer dryness-wetness. The classification of temperature have been reworked into peer reviewed (2) series (AD 1000-present) of seasonal temperatures and temperature indices, the so called LCT (Low Countries Temperature) series, now incorporated in the Millennium databases. Recently we started a study to convert the dryness-wetness classifications into a series of precipitation; the so called LCP (Low Countries Precipitation) series. A brief outline is given here of the applied methodology and preliminary results. The WMO definition for meteorological drought has been followed being that a period is called wet respectively dry when the amount of precipitation is considerable more respectively less than usual (normal). To gain a more quantitative insight for four locations, geographically spread over the Low Countries area (De Bilt, Vlissingen, Maastricht and Uccle), we analysed the statistics of daily precipitation series, covering the period 1900-present. This brought us to the following definition, valid for the Low Countries: A period is considered as (very) dry respectively (very) wet if over a continuous period of at least 60 days (~two months) cq 90 days (~three months) on at least two out of the four locations 50% less resp. 50% more than the normal amount for the location (based on the 1961-1990 normal period) has been measured. This results into the following classification into five drought classes hat could be applied to non instrumental observations: Very wet period

  12. Anhydrite precipitation in seafloor hydrothermal systems

    Science.gov (United States)

    Theissen-Krah, Sonja; Rüpke, Lars H.

    2016-04-01

    The composition and metal concentration of hydrothermal fluids venting at the seafloor is strongly temperature-dependent and fluids above 300°C are required to transport metals to the seafloor (Hannington et al. 2010). Ore-forming hydrothermal systems and high temperature vents in general are often associated with faults and fracture zones, i.e. zones of enhanced permeabilities that act as channels for the uprising hydrothermal fluid (Heinrich & Candela, 2014). Previous numerical models (Jupp and Schultz, 2000; Andersen et al. 2015) however have shown that high permeabilities tend to decrease fluid flow temperatures due to mixing with cold seawater and the resulting high fluid fluxes that lead to short residence times of the fluid near the heat source. A possible mechanism to reduce the permeability and thereby to focus high temperature fluid flow are mineral precipitation reactions that clog the pore space. Anhydrite for example precipitates from seawater if it is heated to temperatures above ~150°C or due to mixing of seawater with hydrothermal fluids that usually have high Calcium concentrations. We have implemented anhydrite reactions (precipitation and dissolution) in our finite element numerical models of hydrothermal circulation. The initial results show that the precipitation of anhydrite efficiently alters the permeability field, which affects the hydrothermal flow field as well as the resulting vent temperatures. C. Andersen et al. (2015), Fault geometry and permeability contrast control vent temperatures at the Logatchev 1 hydrothermal field, Mid-Atlantic Ridge, Geology, 43(1), 51-54. M. D. Hannington et al. (2010), Modern Sea-Floor Massive Sulfides and Base Metal Resources: Toward an Estimate of Global Sea-Floor Massive Sulfide Potential, in The Challenge of Finding New Mineral Resources: Global Metallogeny, Innovative Exploration, and New Discoveries, edited by R. J. Goldfarb, E. E. Marsh and T. Monecke, pp. 317-338, Society of Economic Geologists

  13. A composite study of the MJO influence on the surface air temperature and precipitation over the Continental United States

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Shuntai [NOAA/NWS/NCEP, Camp Springs, MD (United States); Wyle, Inc., McLean, VA (United States); L' Heureux, Michelle; Weaver, Scott; Kumar, Arun [NOAA/NWS/NCEP, Camp Springs, MD (United States)

    2012-04-15

    The influence of the MJO on the continental United States (CONUS) surface air temperature (SAT) and precipitation is examined based on 30 years of daily data from 1979-2008. Composites are constructed for each of the eight phases of the Wheeler-Hendon MJO index over 12 overlapping three-month seasons. To ensure that the MJO signal is distinguished from other patterns of climate variability, several steps are taken: (a) only days classified as ''MJO events'' are used in the composites, (b) statistical significance of associated composites is assessed using a Monte Carlo procedure, and (c) intraseasonal frequencies are matched to the unfiltered data. Composites of other fields are also shown in order to examine how the SAT and precipitation anomalies are associated with large-scale circulations providing a link between the tropics and extratropics. The strongest and most significant MJO effects on SAT are found during the northern winter seasons. When enhanced convection is located over the equatorial Indian Ocean, below-average SAT tends to occur in New England and the Great Lakes region. As enhanced tropical convection shifts over the Maritime continent, above-average SAT appears in the eastern states of the US from Maine to Florida. The MJO influence on precipitation is also significant during northern winter seasons. When enhanced convection is located over the Maritime continent, more precipitation is observed in the central plains of the US. Enhanced precipitation also occurs over the west coast of the US when convective activity is stronger over the Indian Ocean. During the northern summer and fall, the MJO impact on precipitation is mainly significant at lower latitudes, over Mexico and southeastern US. (orig.)

  14. A review of precipitation and temperature control on seedling emergence and establishment for ponderosa and lodgepole pine forest regeneration

    Science.gov (United States)

    Petrie, Matthew; Wildeman, A.M.; Bradford, John B.; Hubbard, R.M.; Lauenroth, W.K.

    2016-01-01

    The persistence of ponderosa pine and lodgepole pine forests in the 21st century depends to a large extent on how seedling emergence and establishment are influenced by driving climate and environmental variables, which largely govern forest regeneration. We surveyed the literature, and identified 96 publications that reported data on dependent variables of seedling emergence and/or establishment and one or more independent variables of air temperature, soil temperature, precipitation and moisture availability. Our review suggests that seedling emergence and establishment for both species is highest at intermediate temperatures (20 to 25 °C), and higher precipitation and higher moisture availability support a higher percentage of seedling emergence and establishment at daily, monthly and annual timescales. We found that ponderosa pine seedlings may be more sensitive to temperature fluctuations whereas lodgepole pine seedlings may be more sensitive to moisture fluctuations. In a changing climate, increasing temperatures and declining moisture availability may hinder forest persistence by limiting seedling processes. Yet, only 23 studies in our review investigated the effects of driving climate and environmental variables directly. Furthermore, 74 studies occurred in a laboratory or greenhouse, which do not often replicate the conditions experienced by tree seedlings in a field setting. It is therefore difficult to provide strong conclusions on how sensitive emergence and establishment in ponderosa and lodgepole pine are to these specific driving variables, or to investigate their potential aggregate effects. Thus, the effects of many driving variables on seedling processes remain largely inconclusive. Our review stresses the need for additional field and laboratory studies to better elucidate the effects of driving climate and environmental variables on seedling emergence and establishment for ponderosa and lodgepole pine.

  15. Precipitation kinetics in warm forming of AW-7020 alloy

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, M., E-mail: Manoj.kumar@ait.ac.at [Leichtmetall-Kompetenzzentrum Ranshofen GmbH, Austrian Institute of Technology, Postfach 26, A-5282 Ranshofen (Austria); Institute of Material Science and Technology, TU Vienna (Austria); Poletti, C. [Present address: Institute of Material Science and Welding, TU Graz (Austria); Institute of Material Science and Technology, TU Vienna (Austria); Degischer, H.P. [Institute of Material Science and Technology, TU Vienna (Austria)

    2013-01-20

    The warm formability of the precipitation hardening AW-7020 (AlZn 4.5Mg1) alloy is investigated by testing extruded tubes. The precipitation kinetics of different conditions before and after warm deformation is studied by differential scanning calorimetry and transmission electron microcopy. The precipitation conditions are correlated with the results of hardness tests at room temperature and of tensile tests at temperatures between 200 and 350 Degree-Sign C at different strain rates. The yield strength decreases with increasing test temperature approaching that of samples in the annealed condition, while the strain at fracture increases. The overall influence of the strain rate on ductility is dominated by the corresponding time required for deformation. The formability of the starting condition T1 as well as the corresponding strain hardening exponent is particularly promising for high strain rates at 250 Degree-Sign C, where the metastable precipitates of the T1 condition are dissolved. The short exposure of about 30 s at 250 Degree-Sign C re-establishes the potential for precipitation strengthening by natural ageing after the warm deformation and a following paint baking heat treatment maintains the hardness level.

  16. Microstructural effects on the yield strength and its temperature dependence in a bainitic precipitation hardened Cr-Mo-V steel

    International Nuclear Information System (INIS)

    Toerroenen, K.; Kotilainen, H.; Nenonen, P.

    1980-03-01

    The plastic deformation behaviour of a precipitation hardened bainitic Cr-Mo-V steel is analyzed at ambient and low temperatures. The temperature dependent component of the yield strength is composed of the Peierls-Nabarro force and also partly of the strengthening contribution of the lath- and cell boundaries or the solid solution hardening. The temperature dependence below 230 K is in accordance with the models presented by Yanoshevich and Ryvkina as well as Dorn and Rajnak. The temperature independent component can be calculated merely from the dislocation density, which is stabilized by the vanadium-rich carbides. The linear additivity cannot be used for the superposition of the strengthening effects of various strengthening parameters, By using the phenomenological approach starting from the dislocation movement mechanisms upon yielding the laws for the superposition are discussed. (author)

  17. Formation of Green compact structure of low-temperature ceramics with taking into account the thermal degradation of the binder

    Science.gov (United States)

    Tovpinets, A. O.; Leytsin, V. N.; Dmitrieva, M. A.; Ivonin, I. V.; Ponomarev, S. V.

    2017-12-01

    The solution of the tasks in the field of creating and processing materials for additive technologies requires the development of a single theory of materials for various applications and processes. A separate class of materials that are promising for use in additive technologies includes materials whose consolidation is ensured by the presence of low-melting components in the initial mixture which form a matrix at a temperature not exceeding the melting point, recrystallization or destruction of any of the responsible refractory components of the initial dispersion. The study of the contribution of the binder thermal destruction to the structure and phase composition of the initial compact of the future composite is essential for the development of modern technologies for the synthesis of low-temperature ceramics. This paper investigates the effect of the thermal destruction of a binder on the formation of a green compact of low-temperature ceramics and the structural-mechanical characteristics of sintered ceramics. The approach proposed in Ref. [1] for evaluating the structure and physical characteristics of sintered low-temperature ceramics is improved to clarify the structure of green compacts obtained after thermal destruction of the polymer binder, with taking into account the pores formed and the infusible residue. The obtained results enable a more accurate prediction of thermal stresses in the matrix of sintered ceramics and serve as a basis for optimization.

  18. Monitoring of Calcite Precipitation in Hardwater Lakes with Multi-Spectral Remote Sensing Archives

    Directory of Open Access Journals (Sweden)

    Iris Heine

    2017-01-01

    Full Text Available Calcite precipitation is a common phenomenon in calcium-rich hardwater lakes during spring and summer, but the number and spatial distribution of lakes with calcite precipitation is unknown. This paper presents a remote sensing based method to observe calcite precipitation over large areas, which are an important prerequisite for a systematic monitoring and evaluation of restoration measurements. We use globally archived satellite remote sensing data for a retrospective systematic assessment of past multi-temporal calcite precipitation events. The database of this study consists of 205 data sets that comprise freely available Landsat and Sentinel 2 data acquired between 1998 and 2015 covering the Northeast German Plain. Calcite precipitation is automatically identified using the green spectra and the metric BGR area, the triangular area between the blue, green and red reflectance value. The validation is based on field measurements of CaCO3 concentrations at three selected lakes, Feldberger Haussee, Breiter Luzin and Schmaler Luzin. The classification accuracy (0.88 is highest for calcite concentrations ≥0.7 mg/L. False negative results are caused by the choice of a conservative classification threshold. False positive results can be explained by already increased calcite concentrations. We successfully transferred the developed method to 21 other hardwater lakes in Northeast Germany. The average duration of lakes with regular calcite precipitation is 37 days. The frequency of calcite precipitation reaches from single time detections up to detections nearly every year. False negative classification results and gaps in Landsat time series reduce the accuracy of frequency and duration monitoring, but in future the image density will increase by acquisitions of Sentinel-2a (and 2b. Our study tested successfully the transfer of the classification approach to Sentinel-2 images. Our study shows that 15 of the 24 lakes have at least one phase of

  19. Climate Prediction Center(CPC)Daily GOES Precipitation Index (GPI)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — GOES Precipitation Index (GPI) is a precipitation estimation algorithm. The GPI technique estimates tropical rainfall using cloud-top temperature as the sole...

  20. Quantifying the effects of LUCCs on local temperatures, precipitation, and wind using the WRF model.

    Science.gov (United States)

    Lian, Lishu; Li, Baofu; Chen, Yaning; Chu, Cuicui; Qin, Yanhua

    2017-09-11

    Land use/cover changes (LUCCs) are an important cause of regional climate changes, but the contribution of LUCCs to regional climate changes is not clear. In this study, the Weather Research and Forecasting (WRF) model and statistical methods were used to investigate changes in meteorologic variables in January, April, July, and October 2013 due to local LUCCs from 1990 to 2010 in southern Shandong province, China. The results indicate that the WRF model simulates temperatures in the region well, with high correlation coefficients (0.86-0.97, p wind speed and direction substantially during these four months: average wind speeds increased by 0.02 and 0.01 m/s in January and October, respectively, and decreased by 0.02 and 0.05 m/s in April and July, respectively. Overall, The LUCCs affected spring temperatures the least and summer precipitation the most.

  1. Land Use in LCA: Including Regionally Altered Precipitation to Quantify Ecosystem Damage.

    Science.gov (United States)

    Lathuillière, Michael J; Bulle, Cécile; Johnson, Mark S

    2016-11-01

    The incorporation of soil moisture regenerated by precipitation, or green water, into life cycle assessment has been of growing interest given the global importance of this resource for terrestrial ecosystems and food production. This paper proposes a new impact assessment model to relate land and water use in seasonally dry, semiarid, and arid regions where precipitation and evapotranspiration are closely coupled. We introduce the Precipitation Reduction Potential midpoint impact representing the change in downwind precipitation as a result of a land transformation and occupation activity. Then, our end-point impact model quantifies terrestrial ecosystem damage as a function of precipitation loss using a relationship between woody plant species richness, water and energy regimes. We then apply the midpoint and end-point models to the production of soybean in Southeastern Amazonia which has resulted from the expansion of cropland into tropical forest, with noted effects on local precipitation. Our proposed cause-effect chain represents a complementary approach to previous contributions which have focused on water consumption impacts and/or have represented evapotranspiration as a loss to the water cycle.

  2. Study of precipitation behaviour of Mo and Zr in nitric acid solution

    International Nuclear Information System (INIS)

    Lin Cansheng; Wang Xiaoying; Zhang Chonghai

    1992-01-01

    The precipitation behaviour of Mo and Zr which depends on the concentrations of Mo, Zr, nitric acid and temperature is studied. Precipitation, post-precipitation and ultracentrifugation experiments are made at 100 deg C, 80 deg C, 60 deg C, 40 deg C and room temperatures in the range of 0.6-6.0 mol/1 nitric acid. The experimental feeds are made up of molybdenum labelled with 99 Mo, zirconium labelled with 95 Zr and nitric acid solution. The feed is allowed to stand at constant temperature for some time for the observation of precipitation behaviour. The filtered precipitate and ultracentrifuged liquid is to be measured with HP (Ge)-multichannel analyser in order to determine the content of Mo, Zr and their mole ration in the precipitate and to find out whether there is colloid in the liquid. The results show that the mixed solution of Mo and Zr can produce precipitate and post-precipitate in nitric acid. If the filtrated liquid is allowed to stand for some time, precipitate can be produced again, until the concentration of Mo and Zr in the feed is too low to form precipitate, such as 2.5 x 10 -3 mol/1. If the concentration of nitric acid is less than 4.0 mol/1, the precipitation is produced easily and more precipitate is formed. Precipitation is slower in solutions which are more than 4.0 mol/1 in HNO 3 . The mole-ratio of Mo to Zr in the precipitate is 2 to 1 and it is not dependent on that ratio in the system

  3. Choice of precipitant and calcination temperature of precursor for synthesis of NiCo2O4 for control of CO-CH4 emissions from CNG vehicles.

    Science.gov (United States)

    Trivedi, Suverna; Prasad, Ram

    2018-03-01

    Compressed natural gas (CNG) is most appropriate an alternative of conventional fuel for automobiles. However, emissions of carbon-monoxide and methane from such vehicles adversely affect human health and environment. Consequently, to abate emissions from CNG vehicles, development of highly efficient and inexpensive catalysts is necessary. Thus, the present work attempts to scan the effects of precipitants (Na 2 CO 3 , KOH and urea) for nickel cobaltite (NiCo 2 O 4 ) catalysts prepared by co-precipitation from nitrate solutions and calcined in a lean CO-air mixture at 400°C. The catalysts were used for oxidation of a mixture of CO and CH 4 (1:1). The catalysts were characterized by X-ray diffractometer, Brunauer-Emmett-Teller surface-area, X-ray photoelectron spectroscopy; temperature programmed reduction and Scanning electron microscopy coupled with Energy-Dispersive X-Ray Spectroscopy. The Na 2 CO 3 was adjudged as the best precipitant for production of catalyst, which completely oxidized CO-CH 4 mixture at the lowest temperature (T 100 =350°C). Whereas, for catalyst prepared using urea, T 100 =362°C. On the other hand the conversion of CO-CH 4 mixture over the catalyst synthesized by KOH limited to 97% even beyond 400°C. Further, the effect of higher calcination temperatures of 500 and 600°C was examined for the best catalyst. The total oxidation of the mixture was attained at higher temperatures of 375 and 410°C over catalysts calcined at 500 and 600°C respectively. Thus, the best precipitant established was Na 2 CO 3 and the optimum calcination temperature of 400°C was found to synthesize the NiCo 2 O 4 catalyst for the best performance in CO-CH 4 oxidation. Copyright © 2017. Published by Elsevier B.V.

  4. Seasonal Precipitation Variability Effects on Carbon Exchange in a Tropical Dry Forest of Northwest Mexico

    Science.gov (United States)

    Verduzco, V.; Garatuza-Payan, J.; Yépez, E. A.; Watts, C. J.; Rodriguez, J. C.; Robles-Morua, A.; Vivoni, E. R.

    2015-12-01

    The Tropical Dry Forest (TDF) cover a large area in tropical and subtropical regions in the Americas and its productivity is thought to have an important contribution to the atmospheric carbon fluxes. However, due to this ecosystem complex dynamics, our understanding about the mechanisms controlling net ecosystem exchange is limited. In this study, five years of continue water and carbon fluxes measurements from eddy covariance complemented with remotely sensed vegetation greenness were used to investigate the ecosystem carbon balance of a TDF in the North American Monsoon region under different hydro climatic conditions. We identified a large CO2 efflux at the start of the summer season that is strongly related to the preceding winter precipitation and greenness. Since this CO2 efflux occurs prior to vegetation green-up, we infer a predominant heterotrophic control owed to high decomposition of accumulated labile soil organic matter from prior growing season. Overall, ecosystem respiration has an important effect on the net ecosystem production over the year, but can be overwhelmed by the strength of the primary productivity during the monsoon season. Precipitation characteristics during the monsoon have significant controls on sustaining carbon fixation in the TDF ecosystem into the fall season. A threshold of ~350 to 400 mm of summer precipitation was identify to switch the annual carbon balance in the TDF ecosystem from a net source (+102 g C/m2/yr) to a net sink (-249 g C/m2/yr). This research points at the needs for understanding the potential effects of changing seasonal precipitation patterns on ecosystem dynamics and carbon sequestration in subtropical regions.

  5. Dynamical and statistical downscaling of precipitation and temperature in a Mediterranean area

    KAUST Repository

    Pizzigalli, Claudia

    2012-03-28

    In this paper we present and discuss a comparison between statistical and regional climate modeling techniques for downscaling GCM prediction . The comparison is carried out over the “Capitanata” region, an area of agricultural interest in south-eastern Italy, for current (1961-1990) and future (2071–2100) climate. The statistical model is based on Canonical Correlation Analysis (CCA), associated with a data pre-filtering obtained by a Principal Component Analysis (PCA), whereas the Regional Climate Model REGCM3 was used for dynamical downscaling. Downscaling techniques were applied to estimate rainfall, maximum and minimum temperatures and average number of consecutive wet and dry days. Both methods have comparable skills in estimating stations data. They show good results for spring, the most important season for agriculture. Both statistical and dynamical models reproduce the statistical properties of precipitation well, the crucial variable for the growth of crops.

  6. Study of precipitation phenomena during the creep of austenitic stainless steels

    International Nuclear Information System (INIS)

    Le May, I.; Bassett, B.J.; White, W.E.

    1975-01-01

    Creep-rupture data for two austenitic stainless steels, AISI Types 310 and 316, are presented, together with observations of precipitation taking place during creep. While the effects of creep deformation on precipitation in the Type 310 were negligible, ferrite precipitation was considerably greater in the Type 316 undergoing creep than in unstressed material. Ferrite precipitation appears to promote grain boundary cavitation and internal cracking, thus reducing creep resistance and a correlation has been noted between increased ferrite precipitation and apparent further weakening of the Type 316 over the temperature range 730 to 800 0 C approximately, as evidenced by breaks in the isostress lines on a plot of log (time to rupture) versus temperature

  7. Modeling studies on the precipitation of Kr after implantation into metals

    International Nuclear Information System (INIS)

    Rest, J.

    1988-02-01

    A rate-theory approach is applied to interpreting observations on the precipitation of Kr injected into Ni at temperatures between 25 and 560/degree/C. At temperatures of 400/degree/C or higher, the implanted Kr precipitates evolve into a bi-modal size distribution containing small solid precipitates and an additional population of larger, faceted bubbles. The calculations explore the dependence of the observed bi-modal distribution on the maximum size of the solid Kr precipitates and the effect of this dependence on bubble mobility. The analysis suggests that during the irradiation, whereas the large bubbles move by surface diffusion, the solid Kr precipitates are immobile. The relevance of the Kr-Ni interaction on the solid Kr precipitates size cutoff is discussed. 18 refs., 8 figs., 2 tabs

  8. The bosonic thermal Green function, its dual, and the fermion correlators of the massive Thirring model at finite temperature

    International Nuclear Information System (INIS)

    Mondaini, Leonardo; Marino, E.C.

    2011-01-01

    Full text: Despite the fact that quantum field theories are usually formulated in coordinate space, calculations, in both T = 0 and T ≠ 0 cases, are almost always performed in momentum space. However, when we are faced with the exact calculation of correlation functions we are naturally led to the problem of finding closed-form expressions for Green functions in coordinate space. In the present work, we derive an exact closed-form representation for the Euclidian thermal Green function of the two-dimensional (2D) free massless scalar field in coordinate space. This can be interpreted as the real part of a complex analytic function of a variable that conformally maps the infinite strip -∞ < x < ∞ (0 < τ < β of the z = x + iτ (τ: imaginary time) plane into the upper-half-plane. Use of the Cauchy-Riemann conditions, then allows us to identify the dual thermal Green function as the imaginary part of that function. Using both the thermal Green function and its dual, we obtain an explicit series expression for the fermionic correlation functions of the massive Thirring model (MTM) at a finite temperature. (author)

  9. One-pot low-temperature green synthesis of magnetic graphene nanocomposite for the selective reduction of nitrobenzene

    Science.gov (United States)

    Haridas, Vijayasree; Sugunan, Sankaran; Narayanan, Binitha N.

    2018-06-01

    In the present study, a green one-pot low-temperature method is adopted for the synthesis of a novel magnetic graphene nanocomposite catalyst. Graphene preparation is performed without employing any oxidizing agents or corrosive chemicals, under mild sonication in isopropyl alcohol - water mixture. Monolayered nanoplatelets of graphene are obtained in the green solvent mixture and the composite material is found to be ferromagnetic in nature, obvious from the vibrating sample magnetometric measurements. Fe in the nanocomposite exists in two different forms i.e., α-Fe2O3 and α-FeOOH, as evident from the material characterization results. The graphene nanocomposite is found to be highly efficient in the selective reduction of nitrobenzene to aniline under solvent free reaction conditions and magnetic separation of this fine nanomaterial from the reaction mixture is successfully carried out. The catalyst is efficiently reusable till five repeated cycles.

  10. Precipitation-strengthening effects in iron-aluminides

    Energy Technology Data Exchange (ETDEWEB)

    Maziasz, P.J.; McKamey, C.G.; Goodwin, G.M. [Oak Ridge National Laboratory, TN (United States)] [and others

    1995-05-01

    The purpose of this work is to produce precipitation to improve both high-temperature strength and room-temperature ductibility in FeAl-type(B2 phase) iron-aluminides. Previous work has focused on primarily wrought products, but stable precipitates can also refine the grain size and affect the properties of as-cast and/or welded material as well. New work began in FY 1994 on the properties of these weldable, strong FeAl alloys in the as-cast condition. Because the end product of this project is components for industry testing, simpler and better (cheaper, near-net-shape) processing methods must be developed for industrial applications of FeAl alloys.

  11. A laboratory study of ikaite (CaCO3·6H2O) precipitation as a function of pH, salinity, temperature and phosphate concentration

    OpenAIRE

    Hu, Yu-Bin; Wolf-Gladrow, Dieter A.; Dieckmann, Gerhard S.; Völker, Christoph; Nehrke, Gernot

    2014-01-01

    Ikaite (CaCO3·6H2O) has only recently been discovered in sea ice, in a study that also provided first direct evidence of CaCO3 precipitation in sea ice. However, little is as yet known about the impact of physico-chemical processes on ikaite precipitation in sea ice. Our study focused on how the changes in pH, salinity, temperature and phosphate (PO4) concentration affect the precipitation of ikaite. Experiments were set up at pH from 8.5 to 10.0, salinities from 0 to 105 (in both artificial ...

  12. Climatic change of summer temperature and precipitation in the Alpine region - a statistical-dynamical assessment

    Energy Technology Data Exchange (ETDEWEB)

    Heimann, D.; Sept, V.

    1998-12-01

    Climatic changes in the Alpine region due to increasing greenhouse gas concentrations are assessed by using statistical-dynamical downscaling. The downscaling procedure is applied to two 30-year periods (1971-2000 and 2071-2100, summer months only) of the output of a transient coupled ocean/atmosphere climate scenario simulation. The downscaling results for the present-day climate are in sufficient agreement with observations. The estimated regional climate change during the next 100 years shows a general warming. The mean summer temperatures increase by about 3 to more than 5 Kelvin. The most intense climatic warming is predicted in the western parts of the Alps. The amount of summer precipitation decreases in most parts of central Europe by more than 20 percent. Only over the Adriatic area and parts of eastern central Europe an increase in precipitation is simulated. The results are compared with observed trends and results of regional climate change simulations of other authors. The observed trends and the majority of the simulated trends agree with our results. However, there are also climate change estimates which completely contradict with ours. (orig.) 29 refs.

  13. Urea-assisted low temperature green synthesis of graphene nanosheets for transparent conducting film

    Science.gov (United States)

    Chamoli, Pankaj; Das, Malay K.; Kar, Kamal K.

    2018-02-01

    Present work demonstrates the fabrication of graphene nanosheet (GN) based transparent conducting film (TCF) using spray coating. Green synthesis of GN is carried out by reduction of graphene oxide (GO) using urea as green reducing agent. The reductive ability of urea with varied concentration is studied for GO at low temperature (i.e., 90 °C). As synthesized graphene nanosheets (GNs) are characterized by Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), UV-visible spectroscopy, field emission scanning electron microscopy (FESEM), atomic force microscope (AFM), and X-ray Photon spectroscopy (XPS). Raman analysis confirms that the maximum reduction of oxygen species is noticed using 30 mg/ml urea concentration at 90 °C from GO, and found Raman D to G band ratio (ID/IG) of ∼1.30. XPS analysis validates the Raman signature of removal of oxygen functional groups from GO, and obtained C/O ratio of ∼5.28. Further, transparent conducting films (TCFs) are fabricated using synthesized GNs. Thermal graphitization is carried out to enhance the optical and electrical properties of TCFs. TCF shows best performance when it is annealed at 900 °C for 1 h in vacuum, and obtained sheet resistance is ∼1.89 kΩ/□ with transmittance of ∼62.53%.

  14. Precipitation of ordered α2 phase in a near-α titanium alloy with duplex microstructure

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The precipitation of ordered α2 phase in a near-α Ti-6.3A1-4.8Sn-2.0Zr-1.0Mo-0.34Si-0.9Nd (mass fraction) alloy with duplexmicrostructure, during aging at various temperatures, was investigated. It is concluded that the precipitation and growth of the α2 phasecan be controlled by suitable selection of the aging temperature. Aging at higher temperatures can result in the uniform precipitation andgrowth of α2 ordered phase in αp whereas the α2 ordered phase precipitated only at the lamella boundaries and dislocations in βt. Aging ata moderate temperature can promote the tendency of uniform precipitation of α2 phase in both αp and βt-Aging at a relatively low tem-perature is suitable for the uniform precipitation and growth of fine α2 particles throughout both the αp and βt matrix.

  15. Attribution of trends in global vegetation greenness from 1982 to 2011

    Science.gov (United States)

    Zhu, Z.; Xu, L.; Bi, J.; Myneni, R.; Knyazikhin, Y.

    2012-12-01

    Time series of remotely sensed vegetation indices data provide evidence of changes in terrestrial vegetation activity over the past decades in the world. However, it is difficult to attribute cause-and-effect to vegetation trends because variations in vegetation productivity are driven by various factors. This study investigated changes in global vegetation productivity first, and then attributed the global natural vegetation with greening trend. Growing season integrated normalized difference vegetation index (GSI NDVI) derived from the new GIMMS NDVI3g dataset (1982-2011was analyzed. A combined time series analysis model, which was developed from simper linear trend model (SLT), autoregressive integrated moving average model (ARIMA) and Vogelsang's t-PST model shows that productivity of all vegetation types except deciduous broadleaf forest predominantly showed increasing trends through the 30-year period. The evolution of changes in productivity in the last decade was also investigated. Area of greening vegetation monotonically increased through the last decade, and both the browning and no change area monotonically decreased. To attribute the predominant increase trend of productivity of global natural vegetation, trends of eight climate time series datasets (three temperature, three precipitation and two radiation datasets) were analyzed. The attribution of trends in global vegetation greenness was summarized as relaxation of climatic constraints, fertilization and other unknown reasons. Result shows that nearly all the productivity increase of global natural vegetation was driven by relaxation of climatic constraints and fertilization, which play equally important role in driving global vegetation greenness.; Area fraction and productivity change fraction of IGBP vegetation land cover classes showing statistically significant (10% level) trend in GSI NDVIt;

  16. Do green roofs cool the air?

    NARCIS (Netherlands)

    Solcerova, A.; van de Ven, F.H.M.; Wang, Mengyu; Rijsdijk, Michiel; van de Giesen, N.C.

    2017-01-01

    Rapid urbanization and an increasing number and duration of heat waves poses a need to mitigate extremely high temperatures. One of the repeatedly suggested measures to moderate the so called urban heat island are green roofs. This study investigates several extensive sedum-covered green roofs in

  17. Comparative study on precipitation methods of yellow-cake from acid leachate of rock phosphate and Its purification

    International Nuclear Information System (INIS)

    Abow Slama, E. H. Y.

    2009-05-01

    This study was carried-out to leach uranium from rock phosphate using sulphuric acid in presences of potassium chlorate as an oxidant and to investigate the relative purity of different forms of yellow cakes produced with ammonia ((NH 4 ) 2 U 2 O 7 ), magnesia (UO 3 .xH 2 O) and sodium hydroxide (Na 2 U 2 O 7 ) as precipitants, as well as purification of the products with TBP extraction and matching its impurity levels with specification of the commercial products. Alpha-particle spectrometry was for used for determination of activity concentration of uranium isotopes (''2''3''4U and ''2''3''8U) in rock phosphate, resulting green phosphoric acid solution, and in different forms of the yellow cake from which the equivalent mass concentration of uranium was deduced. Likewise, AAS was used for determination of impurities (Pb, Ni, Cd, Fe, Zn, Mn, and Cu). On the average, the activity concentration of uranium in the rock phosphate was 1468±979 Bq/Kg (119.38±79.66 ppm), and 711±252 Bq/L (57.85±20.46 ppm) in the resulting green solution with corresponding percent of dissolution amounting to 48% which is considered low indicating that the experimental conditions (i.e. dissolution container, temperature, PH, retention time) were not optimal. However, the isotopic ratio (''2''3''4U, ''2''3''8U) in all stages of hydrometallurgical process was not much different from unity indicating lack of fractionation. Crude yellow cakes (hydrate uranium trioxide, ammonium diuranate and sodium diuranate) were precipitated from the green solutions prior to separation of iron and once after iron separation. Although, iron was tested using bipyridine and SCN, it was found in all types of crude samples analyzed this might be attributed to either the quality of the reagent used or inhibition of Fe present in the solution by stronger complexing agent. Uranium mass concentration in crude yellow cakes precipitated before iron separation was found following the order: UO 3 .xH 2 O

  18. Precipitation regime influence on oxygen triple-isotope distributions in Antarctic precipitation and ice cores

    Science.gov (United States)

    Miller, Martin F.

    2018-01-01

    The relative abundance of 17O in meteoric precipitation is usually reported in terms of the 17O-excess parameter. Variations of 17O-excess in Antarctic precipitation and ice cores have hitherto been attributed to normalised relative humidity changes at the moisture source region, or to the influence of a temperature-dependent supersaturation-controlled kinetic isotope effect during in-cloud ice formation below -20 °C. Neither mechanism, however, satisfactorily explains the large range of 17O-excess values reported from measurements. A different approach, based on the regression characteristics of 103 ln (1 +δ17 O) versus 103 ln (1 +δ18 O), is applied here to previously published isotopic data sets. The analysis indicates that clear-sky precipitation ('diamond dust'), which occurs widely in inland Antarctica, is characterised by an unusual relative abundance of 17O, distinct from that associated with cloud-derived, synoptic snowfall. Furthermore, this distinction appears to be largely preserved in the ice core record. The respective mass contributions to snowfall accumulation - on both temporal and spatial scales - provides the basis of a simple, first-order explanation for the observed oxygen triple-isotope ratio variations in Antarctic precipitation, surface snow and ice cores. Using this approach, it is shown that precipitation during the last major deglaciation, both in western Antarctica at the West Antarctic Ice Sheet (WAIS) Divide and at Vostok on the eastern Antarctic plateau, consisted essentially of diamond dust only, despite a large temperature differential (and thus different water vapour supersaturation conditions) at the two locations. In contrast, synoptic snowfall events dominate the accumulation record throughout the Holocene at both sites.

  19. Precipitation under cyclic strain in solution-treated Al4wt%Cu I: mechanical behavior

    Energy Technology Data Exchange (ETDEWEB)

    Farrow, Adam M [Los Alamos National Laboratory; Laird, Campbell [UNIV OF PENNSYLVANIA

    2008-01-01

    Solution-treated AL-4wt%Cu was strain-cycled at ambient temperature and above, and the precipitation and deformation behaviors investigated by TEM. Anomalously rapid growth of precipitates appears to have been facilitated by a vacancy super-saturation generated by cyclic strain and the presence of a continually refreshed dislocation density to provide heterogeneous nucleation sites. Texture effects as characterized by Orientation Imaging Microscopy appear to be responsible for latent hardening in specimens tested at room temperature, with increasing temperatures leading to a gradual hardening throughout life due to precipitation. Specimens exhibiting rapid precipitation hardening appear to show a greater effect of texture due to the increased stress required to cut precipitates in specimens machined from rolled plate at an angle corresponding to a lower average Schmid factor. The accelerated formation of grain boundary precipitates appears to be partially responsible for rapid inter-granular fatigue failure at elevated temperatures, producing fatigue striations and ductile dimples coexistent on the fracture surface.

  20. The effects of feedstock pre-treatment and pyrolysis temperature on the production of biochar from the green seaweed Ulva.

    Science.gov (United States)

    Roberts, David A; de Nys, Rocky

    2016-03-15

    Green seaweeds from the genus Ulva are a promising feedstock for the production of biochar for carbon (C) sequestration and soil amelioration. Ulva can be cultivated in waste water from land-based aquaculture and Ulva blooms ("green tides") strand millions of tons of biomass on coastal areas of Europe and China each year. The conversion of Ulva into biochar could recycle C and nutrients from eutrophic water into agricultural production. We produce biochar from Ulva ohnoi, cultivated in waste water from an aquaculture facility, and characterize its suitability for C sequestration and soil amelioration through bio-chemical analyses and plant growth experiments. Two biomass pre-treatments (fresh water rinsing to reduce salt, and pelletisation to increase density) were crossed with four pyrolysis temperatures (300-750 °C). Biomass rinsing decreased the ash and increased the C content of the resulting biochar. However, biochar produced from un-rinsed biomass had a higher proportion of fixed C and a higher yield. C sequestration decreased with increasing pyrolysis temperatures due to the combination of lower yield and lower total C content of biochar produced at high temperatures. Biochar produced from un-rinsed biomass at 300 °C had the greatest gravimetric C sequestration (110-120 g stable C kg(-1) seaweed). Biochar produced from un-pelletised Ulva enhanced plant growth three-fold in low fertility soils when the temperature of pyrolysis was less than 450 °C. The reduced effectiveness of the high-temperature biochars (>450 °C) was due to a lower N and higher salt content. Soil ameliorated with biochar produced from pelletised biomass had suppressed plant germination and growth. The most effective biochar for C sequestration and soil amelioration was produced from un-rinsed and un-pelletised Ulva at 300 °C. The green tide that occurs annually along the Shandong coastline in China generates sufficient biomass (200,000 tons dry weight) to ameliorate 12,500

  1. Continuous precipitation process of plutonium salts

    International Nuclear Information System (INIS)

    Richard, P.

    1967-03-01

    This work concerns the continuous precipitation process of plutonium oxalate. Investigations about the solubility of different valence states in nitric-oxalic and in nitric-sulfuric-oxalic medium lead to select the precipitation process of tetravalent plutonium oxalate. Settling velocity and granulometry of tetravalent oxalate plutonium have been studied with variation of several precipitation parameters such as: temperature, acidity, excess of oxalic acid and aging time. Then are given test results of some laboratory continuous apparatus. Conditions of operation with adopted tubular apparatus are defined in conclusion. A flow-sheet is given for a process at industrial scale. (author) [fr

  2. In-place measurement of specific electric resistance during precipitation of γ'-precipitating Ni base alloys

    International Nuclear Information System (INIS)

    Silomon, M.

    1991-01-01

    During precipitation and coarsening of a second phase, the electric resistance of an alloy changes. Continuous resistance measurement is possible during heat treatment and can be conducted with limited experimental effort; any metallographic determination of the temperature and time dependencies of structural changes, however, requires very high effort. For this reason, an instrument was set up which permits continuous measurement of the resistance at precipitation temperature and during heating or cooling, while providing sufficient resolution for minor changes. Both measuring methods are conducted on technologically relevant alloys such as Nimonic PE 16 and those based on Ni-20 At.% Cr with deliberately varied additions of Al and Ti (accompanying investigations: TEM, SANS, and calorimetry). Their usefulness for alloy development is discussed within the scope of current concepts of demixing kinetics and resistance of alloys. Essential results concern the matrix/γ'-phase mismatch, the Ni 2 Cr short range order, and determination of the γ'-solvus temperature. (orig.) With 53 figs., 4 tabs [de

  3. Effects of temperature and precipitation variability on the risk of violence in sub-Saharan Africa, 1980–2012

    OpenAIRE

    O’Loughlin, John; Linke, Andrew M.; Witmer, Frank D. W.

    2014-01-01

    A robust debate about the effects of climate change on conflict occurrences has attained wide public and policy attention, with sub-Saharan Africa generally viewed as most susceptible to increased conflict risk. Using a new disaggregated dataset of violence and climate anomaly measures (temperature and precipitation variations from normal) for sub-Saharan Africa 1980–2012, we consider political, economic, and geographic factors, not only climate metrics, in assessing the chances of increased ...

  4. Atmospheric Circulation Patterns over East Asia and Their Connection with Summer Precipitation and Surface Air Temperature in Eastern China during 1961-2013

    Science.gov (United States)

    Li, Shuping; Hou, Wei; Feng, Guolin

    2018-04-01

    Based on the NCEP/NCAR reanalysis data and Chinese observational data during 1961-2013, atmospheric circulation patterns over East Asia in summer and their connection with precipitation and surface air temperature in eastern China as well as associated external forcing are investigated. Three patterns of the atmospheric circulation are identified, all with quasi-barotropic structures: (1) the East Asia/Pacific (EAP) pattern, (2) the Baikal Lake/Okhotsk Sea (BLOS) pattern, and (3) the eastern China/northern Okhotsk Sea (ECNOS) pattern. The positive EAP pattern significantly increases precipitation over the Yangtze River valley and favors cooling north of the Yangtze River and warming south of the Yangtze River in summer. The warm sea surface temperature anomalies over the tropical Indian Ocean suppress convection over the northwestern subtropical Pacific through the Ekman divergence induced by a Kelvin wave and excite the EAP pattern. The positive BLOS pattern is associated with below-average precipitation south of the Yangtze River and robust cooling over northeastern China. This pattern is triggered by anomalous spring sea ice concentration in the northern Barents Sea. The anomalous sea ice concentration contributes to a Rossby wave activity flux originating from the Greenland Sea, which propagates eastward to North Pacific. The positive ECNOS pattern leads to below-average precipitation and significant warming over northeastern China in summer. The reduced soil moisture associated with the earlier spring snowmelt enhances surface warming over Mongolia and northeastern China and the later spring snowmelt leads to surface cooling over Far East in summer, both of which are responsible for the formation of the ECNOS pattern.

  5. The Effects of Spectral Nudging on Arctic Temperature and Precipitation Extremes as Produced by the Pan-Arctic WRF

    Science.gov (United States)

    Glisan, J. M.; Gutowski, W. J.; Higgins, M.; Cassano, J. J.

    2011-12-01

    Pan-Arctic WRF (PAW) simulations produced using the 50-km wr50a domain developed for the fully-coupled Regional Arctic Climate Model (RACM) were found to produce deep atmospheric circulation biases over the northern Pacific Ocean, manifested in pressure, geopotential height, and temperature fields. Various remedies were unsuccessfully tested to correct these large biases, such as modifying the physical domain or using different initial/boundary conditions. Spectral (interior) nudging was introduced as a way of constraining the model to be more consistent with observed behavior. However, such control over numerical model behavior raises concerns over how much nudging may affect unforced variability and extremes. Strong nudging may reduce or filter out extreme events, since the nudging pushes the model toward a relatively smooth, large-scale state. The question then becomes - what is the minimum spectral nudging needed to correct the biases occurring on the RACM domain while not limiting PAW simulation of extreme events? To determine this, case studies were devised, using a six-member PAW ensemble on the RACM grid with varying spectral nudging strength. Two simulations were run, one in the cold season (January 2007) and one in a warm season (July 2007). Precipitation and 2-m temperature fields were extracted from the output and analyzed to determine how changing spectral nudging strength impacts both temporal and spatial temperature and precipitation extremes. The maximum and minimum temperatures at each point from among the ensemble members were examined, on the 95th confidence interval. The maximum and minimums over the simulation period will also be considered. Results suggest that there is a marked lack of sensitivity to the degrees of nudging. Moreover, it appears nudging strength can be considerably smaller than the standard strength and still produce reliably good simulations.

  6. Relaxation Behavior by Time-Salt and Time-Temperature Superpositions of Polyelectrolyte Complexes from Coacervate to Precipitate

    Directory of Open Access Journals (Sweden)

    Samim Ali

    2018-01-01

    Full Text Available Complexation between anionic and cationic polyelectrolytes results in solid-like precipitates or liquid-like coacervate depending on the added salt in the aqueous medium. However, the boundary between these polymer-rich phases is quite broad and the associated changes in the polymer relaxation in the complexes across the transition regime are poorly understood. In this work, the relaxation dynamics of complexes across this transition is probed over a wide timescale by measuring viscoelastic spectra and zero-shear viscosities at varying temperatures and salt concentrations for two different salt types. We find that the complexes exhibit time-temperature superposition (TTS at all salt concentrations, while the range of overlapped-frequencies for time-temperature-salt superposition (TTSS strongly depends on the salt concentration (Cs and gradually shifts to higher frequencies as Cs is decreased. The sticky-Rouse model describes the relaxation behavior at all Cs. However, collective relaxation of polyelectrolyte complexes gradually approaches a rubbery regime and eventually exhibits a gel-like response as Cs is decreased and limits the validity of TTSS.

  7. Effect of calcination temperature on the crystallite growth of cerium oxide nano-powders prepared by the co-precipitation process

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jian-Chih [Department of Orthopaedics, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan (China); Chen, Wen-Cheng [School of Dentistry, College of Dental Medicine, Kaohsiung Medical University, Kaohsiung 807, Taiwan (China); Tien, Yin-Chun [Department of Orthopaedics, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan (China); Shih, Chi-Jen, E-mail: cjshih@kmu.edu.t [Department of Fragrance and Cosmetics Science, Kaohsiung Medical University, 100 Shi-Chuan1st Road, Kaohsiung 80708, Taiwan (China)

    2010-04-30

    Cerium oxide nanocrystallites were synthesized by a co-precipitation process at a relatively low temperature, using cerium (III) nitrate as the starting material in a water solution with pH in the range of 8-9. The effect of calcination temperature on the crystallite growth of cerium oxide nano-powders was investigated by X-ray diffraction, transmission electron microscopy and electron diffraction. The crystallization temperature of the cerium oxide powders was estimated to be about 273 K, by XRD analysis. When calcined at temperatures from 473 to 1273 K, face-centered cubic phase crystallization was observed by XRD. The crystallite size of the cerium oxide increased from 12.0 to 48 nm as the calcining temperature increased from 473 to 1273 K, in the pH range 8-9. The activation energy for the growth of cerium oxide nanoparticles was found to have very low values of 17.5 kJ/mol for pH = 8 and 16.0 kJ/mol for pH = 9.

  8. The Assessment of Green Water Based on the SWAT Model: A Case Study in the Hai River Basin, China

    Directory of Open Access Journals (Sweden)

    Kui Zhu

    2018-06-01

    Full Text Available Green water accounts for two-thirds of precipitation, and the proportion could be even higher in dry years. Conflicts between water supply and demand have gradually become severe in the Hai River Basin (HRB due to the socio-economic development. Thus, the exploitation and the utilization of green water have attracted increasing attention. By gathering the related hydrological, meteorological, and geographic data, the spatiotemporal distribution of green water in HRB and the impacts of land use types on green water are analyzed based on the SWAT (Soil and Water Assessment Tool model in this study. Furthermore, three new indices are proposed for evaluation, including the maximum possible storage of green water (MSGW, the consumed green water (CGW, and the utilizable green water (UGW. The results show that (1 the MSGW is relatively low in plain areas and its spatial distribution is significantly associated with the soil type; (2 according to the evaluation results of CGW and UGW in HRB, a further improvement of utilization efficiency of green water could be achieved; (3 in general, the utilization efficiency of precipitation in farmlands is higher than other land use types, which means that the planting of appropriate plants could be helpful to enhance the utilization efficiency of green water. Our results summarize the spatiotemporal distribution of green water resource and provide a reference for water resources management in other water-short agricultural areas.

  9. Relations between oxygen stable isotopic ratios in precipitation and relevant meteorological factors in southwest China

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The correlations of isotopic ratios in precipitation with temperature, air pressure and humidity at dif- ferent altitudes, in southwest China, are analyzed. There appear marked negative correlations for the δ 18O in precipitation with precipitation amount, vapor pressure and atmospheric precipitable water (PW) at Mengzi, Simao and Tengchong stations on synoptic timescale; the marked negative correlations between the δ 18O in precipitation and the diurnal mean temperature at 400 hPa, 500 hPa, 700 hPa and 850 hPa are different from the temperature effect in middle-high-latitude inland. Moreover, the notable positive correlation between the δ 18O in precipitation and the dew-point deficit △Td at different altitudes is found at the three stations. On annual timescale, the annual precipitation amount weighted mean δ 18O display the negative correlations not only with annual precipitation but also with annual mean temperature at 500 hPa. It can be deduced that, in the years with abnormally strong summer monsoon, more warm and wet air from low-latitude oceans is transported northward along the vapor channel located in southwest China and generates abnormally strong rainfall on the way. Meanwhile, the ab- normally strong condensation process will release more condensed latent heat into atmosphere, and lead to the rise of atmospheric temperature during rainfall, but decline of the δ 18O in precipitation. On the contrary, in the years with abnormally weak summer monsoon, the abnormally weak condensation process will release less condensed latent heat into atmosphere, and lead to the decline of atmos- pheric temperature during rainfall, but increase of the δ 18O in precipitation.

  10. Synthesis of InGaZnO4 nanoparticles using low temperature multistep co-precipitation method

    International Nuclear Information System (INIS)

    Wu, Ming-Chung; Hsiao, Kai-Chi; Lu, Hsin-Chun

    2015-01-01

    Indium gallium zinc oxide (InGaZnO 4 , IGZO) has attracted explosive growth in investigations over the last decades as an important material in the thin-film transistor. In this study, the various nitrate precursors, including indium nitrate, gallium nitrate, and zinc nitrate, were prepared from the various metals dissolved in nitric acid. Then, we used these nitrate precursors to synthesize the IGZO precursor powder by the multistep co-precipitation method. The synthesis parameters of the co-precipitation method, such as reaction temperature, pH value and reaction time, were controlled precisely to prepare the high quality IGZO precursor powder. Finally, IGZO precursor powder was calcined at 900 °C. Then, the microstructure, the crystalline structure, the particle size distribution and specific surface area of calcined IGZO precursor powder were characterized by electron transmission microscopy, X-ray diffraction technique, dynamic light scattering method and the surface area and porosimetry analyzer, respectively. The relative density of IGZO tablet sintered at 1200 °C for 12 h is as high as 97.30%, and it showed highly InGaZnO 4 crystalline structure and the large grain size. The IGZO nanoparticles developed in our study has the potential for the high quality target materials used in the application of electronic devices. - Graphical abstract: Display Omitted - Highlights: • InGaZnO 4 (IGZO) nanoparticle was synthesized by multistep co-precipitation method. • The synthesis parameters were controlled precisely to prepare high quality powder. • The relative density of highly crystalline IGZO tablet is as high as 97.30%. • IGZO tablet exhibited highly crystalline structure and the large grain size

  11. Removal of salt from rare earth precipitates by vacuum distillation

    International Nuclear Information System (INIS)

    Yang, Hee-Chul; Eun, Hee-Chul; Cho, Yong-Zun; Park, Hwan-Seo; Kim, In-Tae

    2008-01-01

    This study investigated the distillation rates of LiCl-KCl eutectic salt from the rare earth (RE) precipitates originating from the oxygen-sparging RE precipitation process. The first part study investigated distillation rates of eutectic salt under different vacuums at high temperatures by using thermo-gravimetric furnace system. The second part study tested the removal efficiency of eutectic salt from RE precipitates by using the laboratory vacuum distillation furnace system. Investigated variables were the temperature, the degree of vacuum and the time. Salt distillation operation with a moderated distillation rate of 10 -4 - 10 -5 mole sec -1 cm -2 is possible at temperature less than 1300 K and vacuums of 5-50 Torr, by minimizing the potentials of the RE particle entrainment. An increase in the vaporizing surface area is relatively effective for removing the residual salt in pores of bulk of the precipitated RE particles, when compared to that for the vaporizing time. Over 99.9% of the salt removal from the salt-RE precipitate mixture could be achieved by increasing the vaporizing surface area under moderate vacuum conditions of 50 Torr at 1200 K. (author)

  12. Compound extremes of summer temperature and precipitation leading to intensified departures from natural variability.

    Science.gov (United States)

    Mahony, C. R.; Cannon, A. J.

    2017-12-01

    Climate change can drive local climates outside the range of their historical year-to-year variability, straining the adaptive capacity of ecological and human communities. We demonstrate that interactions between climate variables can produce larger and earlier departures from natural variability than is detectable in individual variables. For example, summer temperature (Tx) and precipitation (Pr) are negatively correlated in most terrestrial regions, such that interannual variability lies along an axis from warm-and-dry to cool-and-wet conditions. A climate change trend perpendicular to this axis, towards warmer-wetter conditions, can depart more quickly from the range of natural variability than a warmer-drier trend. This multivariate "departure intensification" effect is evident in all six CMIP5 models that we examined: 23% (9-34%) of the land area of each model exhibits a pronounced increase in 2σ extremesin the Tx-Pr regime relative to Tx or Pr alone. Observational data suggest that Tx-Pr correlations are sufficient to produce departure intensification in distinct regions on all continents. Departures from the historical Tx-Pr regime may produce ecological disruptions, such as in plant-pathogen interactions and human diseases, that could offset the drought mitigation benefits of increased precipitation. Our study alerts researchers and adaptation practitioners to the presence of multivariate climate change signals and compound extremes that are not detectable in individual climate variables.

  13. A study of precipitation phenomena during the creep of austenitic stainless steels

    International Nuclear Information System (INIS)

    Le May, I.; White, W.E.; Bassett, B.J.

    1975-01-01

    Creep-rupture data for two austenitic stainless steels, AISI Types 310 and 316, are presented, together with observations of precipitation taking place during creep. While the effects of creep deformation on precipitation in the Type 310 were negligible, ferrite precipitation was considerably greater in the Type 316 undergoing creep than in unstressed material. Ferrite precipitation appears to promote grain boundary cavitation and internal cracking, thus reducing creep resistance, and a correlation has been noted between increased ferrite precipitation and apparent further weakening of the Type 316 over the temperature range 730 0 C to 800 0 C approximately, as evidenced by breaks in the isostress lines on a plot of log (time to rupture) versus temperature. (author)

  14. Microstructural and magnetic characterization of iron precipitation in Ni-Fe-Al alloys

    International Nuclear Information System (INIS)

    Duman, Nagehan; Mekhrabov, Amdulla O.; Akdeniz, M. Vedat

    2011-01-01

    The influence of annealing on the microstructural evolution and magnetic properties of Ni 50 Fe x Al 50-x alloys for x = 20, 25, and 30 has been investigated. Solidification microstructures of as-cast alloys reveal coarse grains of a single B2 type β-phase and typical off eutectic microstructure consisting of proeutectic B2 type β dendrites and interdendritic eutectic for x = 20 and x > 20 at.% Fe respectively. However, annealing at 1073 K results in the formation of FCC γ-phase particles along the grain boundaries as well as grain interior in x = 20 at.% Fe alloy. The volume fraction of interdentritic eutectic regions tend to decrease and their morphologies start to degenerate by forming FCC γ-phase for x > 20 at.% Fe alloys with increasing annealing temperatures. Increasing Fe content of alloys induce an enhancement in magnetization and a rise in the Curie transition temperature (T C ). Temperature scan magnetic measurements and transmission electron microscopy reveal that a transient rise in the magnetization at temperatures well above the T C of the alloys would be attributed to the precipitation of a nano-scale ferromagnetic BCC α-Fe phase. Retained magnetization above the Curie transition temperature of alloy matrix, together with enhanced room temperature saturation magnetization of alloys annealed at favorable temperatures support the presence of ferromagnetic precipitates. These nano-scale precipitates are shown to induce significant precipitation hardening of the β-phase in conjunction with enhanced room temperature saturation magnetization in particular when an annealing temperature of 673 K is used. - Research Highlights: → Evolution of microstructure and magnetic properties with varying Fe content. → Transient rise in magnetization via the formation of ferromagnetic phase. → Enhancements in saturation magnetization owing to precipitated ferromagnetic phase. → Nanoscale precipitation of ferromagnetic BCC α-Fe confirmed by TEM.

  15. Precipitation behavior of carbides in high-carbon martensitic stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Qin-tian; Li, Jing; Shi, Cheng-bin; Yu, Wen-tao; Shi, Chang-min [University of Science and Technology, Beijing (China). State Key Laboratory of Advanced Metallurgy; Li, Ji-hui [Yang Jiang Shi Ba Zi Group Co., Ltd, Guangdong (China)

    2017-01-15

    A fundamental study on the precipitation behavior of carbides was carried out. Thermo-calc software, scanning electron microscopy, electron probe microanalysis, transmission electron microscopy, X-ray diffractometry and high-temperature confocal laser scanning microscopy were used to study the precipitation and transformation behaviors of carbides. Carbide precipitation was of a specific order. Primary carbides (M7C3) tended to be generated from liquid steel when the solid fraction reached 84 mol.%. Secondary carbides (M7C3) precipitated from austenite and can hardly transformed into M23C6 carbides with decreasing temperature in air. Primary carbides hardly changed once they were generated, whereas secondary carbides were sensitive to heat treatment and thermal deformation. Carbide precipitation had a certain effect on steel-matrix phase transitions. The segregation ability of carbon in liquid steel was 4.6 times greater that of chromium. A new method for controlling primary carbides is proposed.

  16. Precipitation of ammonium diuranate : a study

    International Nuclear Information System (INIS)

    Krishnamoorthy, T.S.; Mahadevan, N.; Sankar Das, M.

    1991-01-01

    The precipitation of ammonium diuranate (ADU) forms the first step in the production of UO 2 fuel for reactors, and hence the quality and consistency of the ADU precipitate is very important in industrial operations. An investigation, on the precipitation of ADU, was carried out under conditions similar to those in industrial production, to evaluate the effect of various variables on the consistency and the quality of ADU. The variables studied were concentration of uranium and ammonia, pH, temperature and form of ammonia (gas or solution). The properties studied were the settling rate of the precipitates, surface area of the ADUs and calcined oxides and compositional characteristics of the ADUs. Multifactorial experiments and ruggedness tests were applied to identify the parameters to which the precipitation process is most vulnerable, so that such parameters may be controlled effectively. Besides, the effect and the importance of equilibrium conditions during the precipitation process, on the quality of the final ADU, was also established. The paper presents the results of these studies. (author). 6 refs., 3 figs., 7 tabs

  17. Glycine buffered synthesis of layered iron(II)-iron(III) hydroxides (green rusts)

    DEFF Research Database (Denmark)

    Yin, Weizhao; Huang, Lizhi; Pedersen, Emil Bjerglund

    2017-01-01

    Layered Fe(II)-Fe(III) hydroxides (green rusts, GRs) are efficient reducing agents against oxidizing contaminants such as chromate, nitrate, selenite, and nitroaromatic compounds and chlorinated solvents. In this study, we adopted a buffered precipitation approach where glycine (GLY) was used...

  18. Review of Z phase precipitation in 9–12 wt-%Cr steels

    DEFF Research Database (Denmark)

    Danielsen, Hilmar Kjartansson

    2016-01-01

    For high temperature applications, 9–12 wt-%Cr steels in fossil fired power plants rely upon precipitate strengthening from (V,Nb)N MX nitrides for long term creep strength. During prolonged exposure at service temperature, another nitride precipitates: Cr(V,Nb)NZ phase. The Z phases lowly replace......MX, eventually causing a breakdown in creep strength. The present paper reviews the Z phase and its behaviour in 9–12 wt-%Cr steels including thermodynamic modelling, crystal structure, nucleation process and precipitation rate as a function of chemical composition. The influence of Z phase precipitation upon...

  19. Effect of Drying Temperature on Iron Fischer-Tropsch Catalysts Prepared by Solvent Deficient Precipitation

    Directory of Open Access Journals (Sweden)

    Michael K. Albretsen

    2017-01-01

    Full Text Available A novel solvent deficient precipitation (SDP method to produce nanoparticles was studied for its potential in Fischer-Tropsch synthesis (FTS catalysis. Using Fe(NO33·9H2O as the iron-containing precursor, this method produces ferrihydrite particles which are then dried, calcined, reduced, and carbidized to form the active catalytic phase for FTS. Six different drying profiles, including final drying temperatures ranging between 80 and 150°C, were used to investigate the effect of ammonium nitrate (AN, a major by-product of reaction between Fe(NO33·9H2O and NH4HCO3 in the SDP method. Since AN has two phase-transitions within this range of drying temperatures, three different AN phases can exist during the drying of the catalyst precursors. These AN phases, along with physical changes occurring during the phase transitions, may affect the pore structure and the agglomeration of ferrihydrite crystallites, suggesting possible reasons for the observed differences in catalytic performance. Catalysts dried at 130°C showed the highest FTS rate and the lowest methane selectivity. In general, better catalytic performance is related to the AN phase present during drying as follows: phase III > phase II > phase I. However, within each AN phase, lower drying temperatures led to better catalytic properties.

  20. Precipitate strengthening of nanostructured aluminium alloy.

    Science.gov (United States)

    Wawer, Kinga; Lewandowska, Malgorzata; Kurzydlowski, Krzysztof J

    2012-11-01

    Grain boundaries and precipitates are the major microstructural features influencing the mechanical properties of metals and alloys. Refinement of the grain size to the nanometre scale brings about a significant increase in the mechanical strength of the materials because of the increased number of grain boundaries which act as obstacles to sliding dislocations. A similar effect is obtained if nanoscale precipitates are uniformly distributed in coarse grained matrix. The development of nanograin sized alloys raises the important question of whether or not these two mechanisms are "additive" and precipitate strengthening is effective in nanostructured materials. In the reported work, hydrostatic extrusion (HE) was used to obtain nanostructured 7475 aluminium alloy. Nanosized precipitates were obtained by post-HE annealing. It was found that such annealing at the low temperatures (100 degrees C) results in a significant increase in the microhardness (HV0.2) and strength of the nanostructured 7475 aluminium alloy. These results are discussed in terms of the interplay between the precipitation and deformation of nanocrystalline metals.

  1. Effective Assimilation of Global Precipitation

    Science.gov (United States)

    Lien, G.; Kalnay, E.; Miyoshi, T.; Huffman, G. J.

    2012-12-01

    Assimilating precipitation observations by modifying the moisture and sometimes temperature profiles has been shown successful in forcing the model precipitation to be close to the observed precipitation, but only while the assimilation is taking place. After the forecast start, the model tends to "forget" the assimilation changes and lose their extra skill after few forecast hours. This suggests that this approach is not an efficient way to modify the potential vorticity field, since this is the variable that the model would remember. In this study, the ensemble Kalman filter (EnKF) method is used to effectively change the potential vorticity field by allowing ensemble members with better precipitation to receive higher weights. In addition to using an EnKF, two other changes in the precipitation assimilation process are proposed to solve the problems related to the highly non-Gaussian nature of the precipitation variable: a) transform precipitation into a Gaussian distribution based on its climatological distribution, and b) only assimilate precipitation at the location where some ensemble members have positive precipitation. The idea is first tested by the observing system simulation experiments (OSSEs) using SPEEDY, a simplified but realistic general circulation model. When the global precipitation is assimilated in addition to conventional rawinsonde observations, both the analyses and the medium range forecasts are significantly improved as compared to only having rawinsonde observations. The improvement is much reduced when only modifying the moisture field with the same approach, which shows the importance of the error covariance between precipitation and all other model variables. The effect of precipitation assimilation is larger in the Southern Hemisphere than that in the Northern Hemisphere because the Northern Hemisphere analyses are already accurate as a result of denser rawinsonde stations. Assimilation of precipitation using a more comprehensive

  2. Calibration and combination of monthly near-surface temperature and precipitation predictions over Europe

    Science.gov (United States)

    Rodrigues, Luis R. L.; Doblas-Reyes, Francisco J.; Coelho, Caio A. S.

    2018-02-01

    A Bayesian method known as the Forecast Assimilation (FA) was used to calibrate and combine monthly near-surface temperature and precipitation outputs from seasonal dynamical forecast systems. The simple multimodel (SMM), a method that combines predictions with equal weights, was used as a benchmark. This research focuses on Europe and adjacent regions for predictions initialized in May and November, covering the boreal summer and winter months. The forecast quality of the FA and SMM as well as the single seasonal dynamical forecast systems was assessed using deterministic and probabilistic measures. A non-parametric bootstrap method was used to account for the sampling uncertainty of the forecast quality measures. We show that the FA performs as well as or better than the SMM in regions where the dynamical forecast systems were able to represent the main modes of climate covariability. An illustration with the near-surface temperature over North Atlantic, the Mediterranean Sea and Middle-East in summer months associated with the well predicted first mode of climate covariability is offered. However, the main modes of climate covariability are not well represented in most situations discussed in this study as the seasonal dynamical forecast systems have limited skill when predicting the European climate. In these situations, the SMM performs better more often.

  3. Variations of net ecosystem production due to seasonal precipitation differences in a tropical dry forest of northwest Mexico

    Science.gov (United States)

    Verduzco, Vivian S.; Garatuza-Payán, Jaime; Yépez, Enrico A.; Watts, Christopher J.; Rodríguez, Julio C.; Robles-Morua, Agustin; Vivoni, Enrique R.

    2015-10-01

    Due to their large extent and high primary productivity, tropical dry forests (TDF) are important contributors to atmospheric carbon exchanges in subtropical and tropical regions. In northwest Mexico, a bimodal precipitation regime that includes winter precipitation derived from Pacific storms and summer precipitation from the North American monsoon (NAM) couples water availability with ecosystem processes. We investigated the net ecosystem production of a TDF ecosystem using a 4.5 year record of water and carbon fluxes obtained from the eddy covariance method complemented with remotely sensed data. We identified a large CO2 efflux at the start of the summer season that is strongly related to the preceding winter precipitation and greenness. Since this CO2 efflux occurs prior to vegetation green-up, we infer that respiration is mainly due to decomposition of soil organic matter accumulated from the prior growing season. Overall, ecosystem respiration has an important effect on the net ecosystem production but can be overwhelmed by the strength of the primary productivity during the NAM. Precipitation characteristics during NAM have significant controls on sustaining carbon fixation in the TDF into the fall season. We identified that a threshold of ~350 to 400 mm of monsoon precipitation leads to a switch in the annual carbon balance in the TDF ecosystem from a net source (+102 g C/m2/yr) to a net sink (-249 g C/m2/yr). This monsoonal precipitation threshold is typically exceeded one out of every 2 years. The close coupling of winter and summer periods with respect to carbon fluxes suggests that the annual carbon balance is dependent on precipitation amounts in both seasons in TDF ecosystems.

  4. Precipitation hardening in dilute Al–Zr alloys

    Directory of Open Access Journals (Sweden)

    Pedro Henrique Lamarão Souza

    2018-01-01

    Full Text Available The aim of this study was to investigate the effect of solute content (hipoperitectic Al–0.22 wt.%Zr and hiperperitectic Al–0.32 wt.%Zr on the precipitation hardening and microstructural evolution of dilute Al–Zr alloys isothermally aged. The materials were conventionally cast in a muffle furnace, solidified in a water-cooled Cu mold and subsequently heat-treated at the temperature of 650 K (377 °C for 4, 12, 24, 100 and 400 h. Mechanical characterization was performed at room temperature, using a microhardness tester and microstructural characterization was carried out on a Transmission Electron Microscope – TEM. The observed microhardness values increased during isothermal aging, due to the precipitation of nanometer-scale Al3Zr L12 particles. Peak strength was achieved within 100 h of aging. After aging for 400 h, microhardness values presented a slight decrease for both alloys, thus indicating overaging due to the coalescence of precipitates. Microhardness values increased with solute content, due to the precipitation of a higher number density of finer precipitates. After 400 h of heat-treating, coalescence was higher for the alloy with lower solute content and, also, the presence of antiphase boundaries – APBs, planar faults associated with the L12 to D023 structural transition, were observed. Comparing theoretical calculations of the increment in strength due to precipitation strengthening with experimental results, it was observed that their values are in reasonable agreement. The Orowan dislocation looping mechanism takes place during precipitation hardening for both alloys in the peak hardness condition.

  5. Nucleation during gibbsites precipitation with seeds from sodium aluminate solution processed under ultrasound

    Institute of Scientific and Technical Information of China (English)

    陈国辉; 陈启元; 尹周澜; 张斌

    2004-01-01

    The secondary nucleation during gibbsite precipitation with seeds from sodium aluminate solution processed by ultrasound was examined by particle size distribution(PSD) analyses. Experiments indicate that at low temperature(<65 ℃ ) and with low frequency ultrasound, the precipitation efficiency and also the secondary nucleation can be improved. Solution processed by low frequency ultrasound has more nuclei than common liquor does at low temperature. At 55 ℃, precipitation efficiency can he improved by 5.31 %, and the effect promoted by low frequency ultrasound decreases with the increase of temperature.

  6. A model for the formation of lattice defects at silicon oxide precipitates in silicon

    International Nuclear Information System (INIS)

    Vanhellemont, J.; Gryse, O. de; Clauws, P.

    2003-01-01

    The critical size of silicon oxide precipitates and the formation of lattice defects by the precipitates are discussed. An expression is derived allowing estimation of self-interstitial emission by spherical precipitates as well as strain build-up during precipitate growth. The predictions are compared with published experimental data. A model for stacking fault nucleation at oxide precipitates is developed based on strain and self-interstitial accumulation during the thermal history of the wafer. During a low-temperature treatment high levels of strain develop. During subsequent high-temperature treatment, excess strain energy in the precipitate is released by self-interstitial emission leading to favourable conditions for stacking fault nucleation

  7. Precipitation of fluticasone propionate microparticles using supercritical antisolvent

    Directory of Open Access Journals (Sweden)

    A Vatanara

    2009-03-01

    Full Text Available ABSTRACT Background: The ability of supercritical fluids (SCFs, such as carbon dioxide, to dissolve and expand or extract organic solvents and as result lower their solvation power, makes it possible the use of SCFs for the precipitation of solids from organic solutions. The process could be the injection of a solution of the substrate in an organic solvent into a vessel which is swept by a supercritical fluid. The aim of this study was to ascertain the feasibility of supercritical processing to prepare different particulate forms of fluticasone propionate (FP, and to evaluate the influence of different liquid solvents and precipitation temperatures on the morphology, size and crystal habit of particles. Method: The solution of FP in organic solvents, was precipitated by supercritical carbon dioxide (SCCO2 at two pressure and temperature levels. Effects of process parameters on the physicochemical characteristics of harvested microparticles were evaluated. Results: Particle formation was observed only at the lower selected pressure, whilst at the higher pressure, no precipitation of particles was occurred due to dissolution of FP in supercritical antisolvent. The micrographs of the produced particles showed different morphologies for FP obtained from different conditions. The results of thermal analysis of the resulted particles showed that changes in the processing conditions didn't influence thermal behavior of the precipitated particles. Evaluation of the effect of temperature on the size distribution of particles showed that increase in the temperature from 40 oC to 50 oC, resulted in reduction of the mean particle size from about 30 µm to about 12 μm. ‍Conclusion: From the results of this study it may be concluded that, processing of FP by supercritical antisolvent could be an approach for production of diverse forms of the drug and drastic changes in the physical characteristics of microparticles could be achieved by changing the

  8. Connecting Urbanization to Precipitation: the case of Mexico City

    Science.gov (United States)

    Georgescu, Matei

    2017-04-01

    Considerable evidence exists illustrating the influence of urban environments on precipitation. We revisit this theme of significant interest to a broad spectrum of disciplines ranging from urban planning to engineering to urban numerical modeling and climate, by detailing the simulated effect of Mexico City's built environment on regional precipitation. Utilizing the Weather Research and Forecasting (WRF) system to determine spatiotemporal changes in near-surface air temperature, precipitation, and boundary layer conditions induced by the modern-day urban landscape relative to presettlement conditions, I mechanistically link the built environment-induced increase in air temperature to simulated increases in rainfall during the evening hours. This simulated increase in precipitation is in agreement with historical observations documenting observed rainfall increase. These results have important implications for understanding the meteorological conditions leading to the widespread and recurrent urban flooding that continues to plague the Mexico City Metropolitan Area.

  9. Magnetic properties of spinels GeNi2-xCoxO4 systems: Green's function and high-temperature series expansions

    Science.gov (United States)

    El Grini, A.; Salmi, S.; Masrour, R.; Hamedoun, M.; Bouslykhane, K.; Marzouk, A.; Hourmatallah, A.; Benzakour, N.

    2018-06-01

    The Green's function theory and high-temperature series expansions technical have been developed for magnetic systems GeNi2-xCoxO4. We have applied the Green's function theory to evaluate thermal magnetization and magnetic susceptibility for different values of magnetic field and dilution x, considering all components of the magnetization when an external magnetic field is applied in (x,z)-plane. The second theory combined with the Padé approximants method for a randomly diluted Heisenberg magnet is used to deduce the magnetic phase diagram of GeNi2 - xCoxO4 systems. The critical exponents ? and ? and associated with the magnetic susceptibility ? and the correlation length ξ, respectively, have been deduced. The theoretical results are compared with those given by magnetic measurements.

  10. Effect of strain-induced precipitation on dynamic recrystallization in Mg–Al–Sn alloys

    International Nuclear Information System (INIS)

    Kabir, Abu Syed Humaun; Sanjari, Mehdi; Su, Jing; Jung, In-Ho; Yue, Stephen

    2014-01-01

    Two different amounts of tin (Sn) were added to a Mg–3 wt% Al binary alloy to form different amounts of precipitates during hot deformation. The thermodynamic modeling software, FactSage ™ , was used to calculate the amounts of Sn to generate the desired relative levels of precipitation. The alloys were deformed at four different temperatures and three different strain rates to generate different amounts of precipitates. The objective was to study the effect of these precipitates on dynamic recrystallization. The results indicated that the formation of strain-induced precipitates is a function of deformation temperature, strain, and strain rate. The findings also revealed that higher amounts of precipitates reduced the volume fraction of dynamic recrystallization and refined the dynamically recrystallized grain size

  11. Analytical model of radiation-induced precipitation at the surface of dilute binary alloy

    Science.gov (United States)

    Pechenkin, V. A.; Stepanov, I. A.; Konobeev, Yu. V.

    2002-12-01

    Growth of precipitate layer at the foil surface of an undersaturated binary alloy under uniform irradiation is treated analytically. Analytical expressions for the layer growth rate, layer thickness limit and final component concentrations in the matrix are derived for coherent and incoherent precipitate-matrix interfaces. It is shown that the high temperature limit of radiation-induced precipitation is the same for both types of interfaces, whereas layer thickness limits are different. A parabolic law of the layer growth predicted for both types of interfaces is in agreement with experimental data on γ '-phase precipitation at the surface of Ni-Si dilute alloys under ion irradiation. Effect of sputtering on the precipitation rate and on the low temperature limit of precipitation under ion irradiation is discussed.

  12. PRECIPITATION BEHAVIOR IN A Cu-Sn-Ni-Zn-P LEAD FRAME MATERIAL

    Institute of Scientific and Technical Information of China (English)

    W.H. Tian; C.K. Yan; M.Nemoto

    2003-01-01

    Transmission electron microscopy (TEM) observations were carried out for examining the precipitation behavior in a Cu-Sn-Ni-Zn-P lead frame material. TEM observations revealed that the precipitate is hexagonal Ni5P2 and the orientation relationship between the Cu matrix and Ni5P2 precipitate is (111)fcc//(0001)hcp,[101]fcc//[11-20]hcp, where the suffix fcc denotes the Cu matrix and hcp denotes the hexagonal Ni5P2 precipitate. The NisP2 precipitate is ovoidal in shape at the beginning of aging at lower temperature. By prolonging the aging time or increasing the aging temperature, Ni5P2 precipitate grows and shows a rod-like shape. The Ni added Cu based lead frame material has a comparative mechanical properties with that of TAMAC15 which has been developed and used in electrical industry.

  13. Characterization Of Mg(OH)2 Precipitation On MSF Desalination Process

    International Nuclear Information System (INIS)

    Sumijanto

    2000-01-01

    The experiment of Mg(OH) sub.2 precipitation has been carry out. Experiment took please by heating sea water simulation with consist of 142 ppm bicarbonate and magnesium ion at temperature 40, 50, 60, 70, 80, 90, 100, 110, and 120 exp.oC respectively by using autoclave. Sampling has been done periodical for 30 minute in interval 300 minute for each temperature. The calculation of Mg(OH) sub.2 precipitation through the decreasing of magnesium concentration with analysis by AAS. From experiment data have the information that Mg(OH) sub.2 precipitation have been formed since 40 exp.oC. From time variable have been the information that the precipitation formed at 30th minute rapidly. Whether at further time the increasing of precipitation are not significant. This phenomena can explained that at each heating step from 40 exp.oC bicarbonate ion be come decomposition with the result carbonate and hydroxide ion and react with magnesium form Mg(OH) sub.2

  14. Structural and magnetic properties of cobalt ferrite nanoparticles synthesized by co-precipitation at increasing temperatures

    Science.gov (United States)

    Stein, C. R.; Bezerra, M. T. S.; Holanda, G. H. A.; André-Filho, J.; Morais, P. C.

    2018-05-01

    This study reports on the synthesis and characterization of cobalt ferrite (CoFe2O4) nanoparticles (NPs) synthesized by chemical co-precipitation in alkaline medium at increasing temperatures in the range of 27 °C to 100 °C. High-quality samples in the size range of 5 to 10 nm were produced using very low stirring speed (250 rpm) and moderate alkaline aqueous solution concentration (4.8 mol/L). Three samples were synthesized and characterized by x-ray diffraction (XRD) and room-temperature (RT) magnetization measurements. All samples present superparamagnetic (SPM) behavior at RT and Rietveld refinements confirm the inverse cubic spinel structure (space group Fd-3m (227)) with minor detectable impurity phase. As the synthesis temperature increases, structural parameters such as lattice constant and grain size change monotonically from 8.385 to 8.383 Å and from 5.8 to 7.4 nm, respectively. Likewise, as the synthesis temperature increases the NPs' magnetic moment and saturation magnetization increases monotonically from 2.6 ×103 to 16×103 μB and from 37 to 66 emu/g, respectively. The RT magnetization (M) versus applied field (H) curves were analyzed by the first-order Langevin function averaged out by a lognormal distribution function of magnetic moments. The excellent curve-fitting of the M versus H data is credited to a reduced particle-particle interaction due to both the SPM behavior and the existence of a surface amorphous shell layer (dead layer), the latter reducing systematically as the synthesis temperature increases.

  15. Dualism of precipitation morphology in high strength low alloy steel

    International Nuclear Information System (INIS)

    Chih-Yuan, Chen; Chien-Chon, Chen; Jer-Ren, Yang

    2015-01-01

    While the role of microalloying elements on precipitation strengthening in ferrite matrix during austenite/ferrite transformation is quite clear, some uncertainty still exists concerning the variability of the microhardness distribution of ferrite grains in the isothermal holding condition. The objective of the present study was to clarify the intrinsic characteristics of carbide precipitation morphology in the ferrite matrix under different processing temperatures and times and to correlate it with austenite decomposition kinetics to elucidate why a large microhardness distribution occurs at low isothermal holding temperature. Better understanding of carbide precipitation behavior can help researchers to determine the root cause of variation in microhardness distribution, which would allow metallurgists to produce high quality steels. Measurement with a Vickers hardness indenter revealed that, in specimens isothermally held at 625 °C, the range of Vickers hardness distribution was 240–420 after 5 min of isothermal holding, and 270–340 after 60 min. For specimens isothermally held at 725 °C, the range of Vickers hardness distribution was 200–330 for 5 min of isothermal holding, and 200–250 for 60 min. Therefore, the average microhardness decreased with the isothermal holding temperature and time, and a larger range of distribution occurred with short isothermal holding times. Transmission electron microscopy (TEM) images showed that interface precipitation and random precipitation can occur within the same ferrite grain. The reason is that the austenite decomposition rate varies with transformation temperature and time. An excessively fast austenite/ferrite interface movement velocity, which usually happens in small ferrite grains, would cause these ferrite grains with microalloying elements to exceed their solubility. Furthermore, these microalloying elements will be precipitated randomly after isothermal holding at longer times. Consequently, a large

  16. Dualism of precipitation morphology in high strength low alloy steel

    Energy Technology Data Exchange (ETDEWEB)

    Chih-Yuan, Chen, E-mail: chen6563@gmail.com [Department of Energy Engineering, National United University, Miaoli 36003, Taiwan (China); Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Chien-Chon, Chen [Department of Energy Engineering, National United University, Miaoli 36003, Taiwan (China); Jer-Ren, Yang, E-mail: jryang@ntu.edu.tw [Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan (China)

    2015-02-25

    While the role of microalloying elements on precipitation strengthening in ferrite matrix during austenite/ferrite transformation is quite clear, some uncertainty still exists concerning the variability of the microhardness distribution of ferrite grains in the isothermal holding condition. The objective of the present study was to clarify the intrinsic characteristics of carbide precipitation morphology in the ferrite matrix under different processing temperatures and times and to correlate it with austenite decomposition kinetics to elucidate why a large microhardness distribution occurs at low isothermal holding temperature. Better understanding of carbide precipitation behavior can help researchers to determine the root cause of variation in microhardness distribution, which would allow metallurgists to produce high quality steels. Measurement with a Vickers hardness indenter revealed that, in specimens isothermally held at 625 °C, the range of Vickers hardness distribution was 240–420 after 5 min of isothermal holding, and 270–340 after 60 min. For specimens isothermally held at 725 °C, the range of Vickers hardness distribution was 200–330 for 5 min of isothermal holding, and 200–250 for 60 min. Therefore, the average microhardness decreased with the isothermal holding temperature and time, and a larger range of distribution occurred with short isothermal holding times. Transmission electron microscopy (TEM) images showed that interface precipitation and random precipitation can occur within the same ferrite grain. The reason is that the austenite decomposition rate varies with transformation temperature and time. An excessively fast austenite/ferrite interface movement velocity, which usually happens in small ferrite grains, would cause these ferrite grains with microalloying elements to exceed their solubility. Furthermore, these microalloying elements will be precipitated randomly after isothermal holding at longer times. Consequently, a large

  17. Consequences of 1.5 °C and 2 °C global warming levels for temperature and precipitation changes over Central Africa

    Science.gov (United States)

    Pokam Mba, Wilfried; Longandjo, Georges-Noel T.; Moufouma-Okia, Wilfran; Bell, Jean-Pierre; James, Rachel; Vondou, Derbetini A.; Haensler, Andreas; Fotso-Nguemo, Thierry C.; Merlin Guenang, Guy; Djiotang Tchotchou, Angennes Lucie; Kamsu-Tamo, Pierre H.; Takong, Ridick R.; Nikulin, Grigory; Lennard, Christopher J.; Dosio, Alessandro

    2018-05-01

    Discriminating climate impacts between 1.5 °C and 2 °C warming levels is particularly important for Central Africa, a vulnerable region where multiple biophysical, political, and socioeconomic stresses interact to constrain the region’s adaptive capacity. This study uses an ensemble of 25 transient Regional Climate Model (RCM) simulations from the CORDEX initiative, forced with the Representative Concentration Pathway (RCP) 8.5, to investigate the potential temperature and precipitation changes in Central Africa corresponding to 1.5 °C and 2 °C global warming levels. Global climate model simulations from the Coupled Model Intercomparison Project phase 5 (CMIP5) are used to drive the RCMs and determine timing of the targeted global warming levels. The regional warming differs over Central Africa between 1.5 °C and 2 °C global warming levels. Whilst there are large uncertainties associated with projections at 1.5 °C and 2 °C, the 0.5 °C increase in global temperature is associated with larger regional warming response. Compared to changes in temperature, changes in precipitation are more heterogeneous and climate model simulations indicate a lack of consensus across the region, though there is a tendency towards decreasing seasonal precipitation in March–May, and a reduction of consecutive wet days. As a drought indicator, a significant increase in consecutive dry days was found. Consistent changes of maximum 5 day