WorldWideScience

Sample records for extreme summer temperatures

  1. Extreme temperatures in summer time. Health implications

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    Julio Díaz Jiménez

    2005-12-01

    Full Text Available The increment that has been detected in summer temperatures in the last years joined to the trends expected to climate for the next century provide an increase in frequency and intensity of the extreme climate events, basically in heat waves. The undoubted relationship between temperature and mortality makes necessary a quantifying in order to characterize the expected effects of temperature over mortality particularly in heat waves.This study show a state-of-the-art review this problem, with a special emphasis in the heat wave that Europe suffered in summer of 2003 and how the heat waves has been characterized until now. Lastly, which are the characteristics that should have the preventive measures designed to minimized the effects of heat waves over population ́s health.

  2. Statistical Downscaling of Summer Temperature Extremes in Northern China

    Institute of Scientific and Technical Information of China (English)

    FAN Lijun; Deliang CHEN; FU Congbin; YAN Zhongwei

    2013-01-01

    Two approaches of statistical downscaling were applied to indices of temperature extremes based on percentiles of daily maximum and minimum temperature observations at Beijing station in summer during 1960-2008.One was to downscale daily maximum and minimum temperatures by using EOF analysis and stepwise linear regression at first,then to calculate the indices of extremes; the other was to directly downscale the percentile-based indices by using seasonal large-scale temperature and geo-potential height records.The cross-validation results showed that the latter approach has a better performance than the former.Then,the latter approach was applied to 48 meteorological stations in northern China.The crossvalidation results for all 48 stations showed close correlation between the percentile-based indices and the seasonal large-scale variables.Finally,future scenarios of indices of temperature extremes in northern China were projected by applying the statistical downscaling to Hadley Centre Coupled Model Version 3 (HadCM3) simulations under the Representative Concentration Pathways 4.5 (RCP 4.5) scenario of the Fifth Coupled Model Inter-comparison Project (CMIP5).The results showed that the 90th percentile of daily maximum temperatures will increase by about 1.5℃,and the 10th of daily minimum temperatures will increase by about 2℃ during the period 2011-35 relative to 1980-99.

  3. Can tree-ring density data reflect summer temperature extremes and associated circulation patterns over Fennoscandia?

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    Zhang, Peng; Ionita, Monica; Lohmann, Gerrit; Chen, Deliang; Linderholm, Hans W.

    2016-12-01

    Tree-ring maximum latewood density (MXD) records from Fennoscandia have been widely used to infer regional- and hemispheric-scale mean temperature variability. Here, we explore if MXD records can also be used to infer past variability of summer temperature extremes across Fennoscandia. The first principal component (PC1) based on 34 MXD chronologies in Fennoscandia explains 50% of the total variance in the observed warm-day extremes over the period 1901-1978. Variations in both observed summer warm-day extremes and PC1 are influenced by the frequency of anomalous anticyclonic pattern over the region, summer sea surface temperatures over the Baltic, North and Norwegian Seas, and the strength of the westerly zonal wind at 200 hPa across Fennoscandia. Both time series are associated with nearly identical atmospheric circulation and SST patterns according to composite map analysis. In a longer context, the first PC based on 3 millennium-long MXD chronologies in central and northern Fennoscandia explains 83% of the total variance of PC1 from the 34 MXD chronologies over the period 1901-1978, 48% of the total variance of the summer warm-day extreme variability over the period 1901-2006, and 36% of the total variance in the frequency of a summer anticyclonic pattern centered over eastern-central Fennoscandia in the period 1948-2006. The frequency of summer warm-day extremes in Fennoscandia is likely linked to a meridional shift of the northern mid-latitude jet stream. This study shows that the MXD network can be used to infer the variability of past summer warm-day extremes and the frequency of the associated summer anticyclonic circulation pattern over Fennoscandia.

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

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    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.

  5. Lack of Dependence of Indian Summer Monsoon Rainfall Extremes on Temperature: An Observational Evidence

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    Vittal, H.; Ghosh, Subimal; Karmakar, Subhankar; Pathak, Amey; Murtugudde, Raghu

    2016-08-01

    The intensification of precipitation extremes in a warming world has been reported on a global scale and is traditionally explained with the Clausius-Clapeyron (C-C) relation. The relationship is observed to be valid in mid-latitudes; however, the debate persists in tropical monsoon regions, with the extremes of the Indian Summer Monsoon Rainfall (ISMR) being a prime example. Here, we present a comprehensive study on the dependence of ISMR extremes on both the 2 m surface air temperature over India and on the sea surface temperature over the tropical Indian Ocean. Remarkably, the ISMR extremes exhibit no significant association with temperature at either spatial scale: neither aggregated over the entire India/Tropical Indian Ocean area nor at the grid levels. We find that the theoretical C-C relation overestimates the positive changes in precipitation extremes, which is also reflected in the Coupled Model Intercomparison Project 5 (CMIP5) simulations. We emphasize that the changing patterns of extremes over the Indian subcontinent need a scientific re-evaluation, which is possible due to availability of the unique long-term in-situ data. This can aid bias correction of model projections of extremes whose value for climate adaptation can hardly be overemphasized, especially for the developing tropical countries.

  6. Extreme summer temperatures in Iberia: health impacts and associated synoptic conditions

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    R. García-Herrera

    2005-02-01

    Full Text Available This paper examines the effect of extreme summer temperatures on daily mortality in two large cities of Iberia: Lisbon (Portugal and Madrid (Spain. Daily mortality and meteorological variables are analysed using the same methodology based on Box-Jenkins models. Results reveal that in both cases there is a triggering effect on mortality when maximum daily temperature exceeds a given threshold (34°C in Lisbon and 36°C in Madrid. The impact of most intense heat events is very similar for both cities, with significant mortality values occurring up to 3 days after the temperature threshold has been surpassed. This impact is measured as the percentual increase of mortality associated to a 1°C increase above the threshold temperature. In this respect, Lisbon shows a higher impact, 31%, as compared with Madrid at 21%. The difference can be attributed to demographic and socio-economic factors. Furthermore, the longer life span of Iberian women is critical to explain why, in both cities, females are more susceptible than males to heat effects, with an almost double mortality impact value.

    The analysis of Sea Level Pressure (SLP, 500hPa geopotential height and temperature fields reveals that, despite being relatively close to each other, Lisbon and Madrid have relatively different synoptic circulation anomalies associated with their respective extreme summer temperature days. The SLP field reveals higher anomalies for Lisbon, but extending over a smaller area. Extreme values in Madrid seem to require a more western location of the Azores High, embracing a greater area over Europe, even if it is not as deep as for Lisbon. The origin of the hot and dry air masses that usually lead to extreme heat days in both cities is located in Northern Africa. However, while Madrid maxima require wind blowing directly from the south, transporting heat from Southern Spain and Northern Africa, Lisbon maxima occur under more easterly

  7. Temperaturas extremas en verano. Implicaciones en salud Extreme temperatures in summer time. Health implications

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    Cristina Linares Gil

    2005-12-01

    Full Text Available El incremento que se ha detectado en las temperaturas estivales en los últimos años, unido las tendencias que se esperan para el clima durante el próximo siglo, hacen prever un aumento en la frecuencia e intensidad de los eventos térmicos extremos, fundamentalmente olas de calor. La clara relación existente entre la temperatura y la mortalidad, hace necesaria una cuantificación para la caracterización de los efectos esperados de la temperatura sobre la mortalidad en las denominadas olas de calor.En este trabajo se presenta una descripción del estado del conocimiento de este problema, haciendo especial referencia a la ola de calor que asoló Europa en el verano de 2003, de cómo se han caracterizado las olas de calor y en base a ello de cuáles son las características que han de tener los planes de alerta y prevención encaminados a minimizar los efectos del calor sobre la salud de la población.The increment that has been detected in summer temperatures in the last years joined to the trends expected to climate for the next century provide an increase in frequency and intensity of the extreme climate events, basically in heat waves. The undoubted relationship between temperature and mortality makes necessary a quantifying in order to characterize the expected effects of temperature over mortality particularly in heat waves.This study show a state-of-the-art review this problem, with a special emphasis in the heat wave that Europe suffered in summer of 2003 and how the heat waves has been characterized until now. Lastly, which are the characteristics that should have the preventive measures designed to minimized the effects of heat waves over population ́s health.

  8. Effects of Urbanization on Extreme Warmest Night Temperatures During Summer near Bohai

    Institute of Scientific and Technical Information of China (English)

    李庆祥; 黄嘉佑

    2013-01-01

    Many previous studies have focused on the impacts of urbanization on regional mean temperatures. Relatively few have analyzed changes in extreme temperatures. Here, we examine the impact of urbanization on extreme warmest night temperatures from 33 stations in the Bohai area between 1958 and 2009. We compute the Generalized Extreme Value (GEV) distribution of extreme warmest night temperatures and analyze long-term variations in its characteristic parameters. A new classification method based on the factor analysis of changes in extreme night temperatures is developed to detect the effects of urbanization in different cities. Of the three parameters that characterize the GEV distribution, the position parameter is the most representative of long-term changes in extreme warmest night temperatures. During the period of rapid urbanization (i.e., after 1978), all three parameters of the GEV distribution are larger for the urban station group than for the reference station group, so are the magnitudes of their variations, and the urban areas have been experiencing higher extreme warmest night temperatures with larger variability. Different types of cities in the Bohai area have all experienced an urban heat island effect, with an average urbanization effect of approximately 0.3℃per decade.

  9. Understanding the rapid summer warming and changes in temperature extremes since the mid-1990s over Western Europe

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    Dong, Buwen; Sutton, Rowan T.; Shaffrey, Len

    2017-03-01

    Analysis of observations indicates that there was a rapid increase in summer (June-August) mean surface air temperature (SAT) since the mid-1990s over Western Europe. Accompanying this rapid warming are significant increases in summer mean daily maximum temperature, daily minimum temperature, annual hottest day temperature and warmest night temperature, and an increase in frequency of summer days and tropical nights, while the change in the diurnal temperature range (DTR) is small. This study focuses on understanding causes of the rapid summer warming and associated temperature extreme changes. A set of experiments using the atmospheric component of the state-of-the-art HadGEM3 global climate model have been carried out to quantify relative roles of changes in sea surface temperature (SST)/sea ice extent (SIE), anthropogenic greenhouse gases (GHGs), and anthropogenic aerosols (AAer). Results indicate that the model forced by changes in all forcings reproduces many of the observed changes since the mid-1990s over Western Europe. Changes in SST/SIE explain 62.2 ± 13.0 % of the area averaged seasonal mean warming signal over Western Europe, with the remaining 37.8 ± 13.6 % of the warming explained by the direct impact of changes in GHGs and AAer. Results further indicate that the direct impact of the reduction of AAer precursor emissions over Europe, mainly through aerosol-radiation interaction with additional contributions from aerosol-cloud interaction and coupled atmosphere-land surface feedbacks, is a key factor for increases in annual hottest day temperature and in frequency of summer days. It explains 45.5 ± 17.6 % and 40.9 ± 18.4 % of area averaged signals for these temperature extremes. The direct impact of the reduction of AAer precursor emissions over Europe acts to increase DTR locally, but the change in DTR is countered by the direct impact of GHGs forcing. In the next few decades, greenhouse gas concentrations will continue to rise and AAer precursor

  10. Understanding the rapid summer warming and changes in temperature extremes since the mid-1990s over Western Europe

    Science.gov (United States)

    Dong, Buwen; Sutton, Rowan T.; Shaffrey, Len

    2016-05-01

    Analysis of observations indicates that there was a rapid increase in summer (June-August) mean surface air temperature (SAT) since the mid-1990s over Western Europe. Accompanying this rapid warming are significant increases in summer mean daily maximum temperature, daily minimum temperature, annual hottest day temperature and warmest night temperature, and an increase in frequency of summer days and tropical nights, while the change in the diurnal temperature range (DTR) is small. This study focuses on understanding causes of the rapid summer warming and associated temperature extreme changes. A set of experiments using the atmospheric component of the state-of-the-art HadGEM3 global climate model have been carried out to quantify relative roles of changes in sea surface temperature (SST)/sea ice extent (SIE), anthropogenic greenhouse gases (GHGs), and anthropogenic aerosols (AAer). Results indicate that the model forced by changes in all forcings reproduces many of the observed changes since the mid-1990s over Western Europe. Changes in SST/SIE explain 62.2 ± 13.0 % of the area averaged seasonal mean warming signal over Western Europe, with the remaining 37.8 ± 13.6 % of the warming explained by the direct impact of changes in GHGs and AAer. Results further indicate that the direct impact of the reduction of AAer precursor emissions over Europe, mainly through aerosol-radiation interaction with additional contributions from aerosol-cloud interaction and coupled atmosphere-land surface feedbacks, is a key factor for increases in annual hottest day temperature and in frequency of summer days. It explains 45.5 ± 17.6 % and 40.9 ± 18.4 % of area averaged signals for these temperature extremes. The direct impact of the reduction of AAer precursor emissions over Europe acts to increase DTR locally, but the change in DTR is countered by the direct impact of GHGs forcing. In the next few decades, greenhouse gas concentrations will continue to rise and AAer precursor

  11. Mechanism of early-summer low-temperature extremes in Japan projected by a nonhydrostatic regional climate model

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    Akihiko Murata

    2014-08-01

    Full Text Available We investigated the mechanisms associated with projected early-summer low-temperature extremes in Japan at the end of the 21st century by means of a well-developed nonhydrostatic regional climate model under the A1B scenario provided by the Intergovernmental Panel on Climate Change-Special Report on Emission Scenario. The projected surface air temperature reveals that even in a climate warmer than that at present, extremely low daily minimum temperatures in early summer are comparable to those in the present climate at several locations. At locations where future low temperatures are remarkable, the temperature drop at night is larger in the future than at present. This temperature drop results from mainly two heat fluxes: upward longwave radiation and latent heat flux. In the future climate, upward longwave radiation increases owing to high temperature at the surface around the time of the sunset. In addition, the upward flux of latent heat increases owing to low relative humidity just above the surface. These dryer conditions are associated with lower relative humidity at 850 hPa, suggesting the effects of synoptic systems. These two fluxes act to reduce the surface temperature, and hence surface air temperature.

  12. Mesoscale convection system and occurrence of extreme low tropopause temperatures. Observations over Asian summer monsoon region

    Energy Technology Data Exchange (ETDEWEB)

    Jain, A.R.; Mandal, T.K.; Gautam, R. [National Physical Laboratory, New Delhi (India). Radio and Atmospheric Div.; Panwar, V. [National Physical Laboratory, New Delhi (India). Radio and Atmospheric Div.; Delhi Univ. (India). Dept. of Physics and Astrophysics; Rao, V.R. [India Meteorology Dept., New Delhi (India). Satellite Meteorology Div.; Goel, A. [Delhi Univ. (India). Dept. of Physics and Astrophysics; Das, S.S. [Vikram Sarabhai Space Center, Trivandrum (India). Space Physics Lab.; Dhaka, S.K. [Delhi Univ., New Delhi (India). Dept. of Physics and Electronics

    2010-07-01

    The present study examines the process of how tropospheric air enters the stratosphere, particularly in association with tropical mesoscale convective systems (TMCS) which are considered to be one of the causative mechanisms for the observation of extremely low tropopause temperature over the tropics. The association between the phenomena of convection and the observation of extreme low tropopause temperature events is, therefore, examined over the Asian monsoon region using data from multiple platforms. Satellite observations show that the area of low outgoing long wave radiation (OLR), which is a proxy for the enhanced convection, is embedded with high altitude clouds top temperatures ({<=}193 K). A detailed analysis of OLR and 100 hPa temperature shows that both are modulated by westward propagating Rossby waves with a period of {proportional_to}15 days, indicating a close linkage between them. The process by which the tropospheric air enters the stratosphere may, in turn, be determined by how the areas of convection and low tropopause temperature (LTT) i.e. T {<=}191K are spatially located. In this context, the relative spatial distribution of low OLR and LTT areas is examined. Though, the locations of low OLR and LTT are noticed in the same broad area, the two do not always overlap, except for partial overlap in some cases. When there are multiple low OLR areas, the LTT area generally appears in between the low OLR areas. Implications of these observations are also discussed. The present analysis also shows that the horizontal mean winds have a role in the spatial distribution of low OLR and LTT. (orig.)

  13. Understanding the rapid summer warming and changes in temperature extremes since the mid-1990s over Western Europe

    OpenAIRE

    Dong, Buwen; Rowan T Sutton; Shaffrey, Len; Buwen Dong

    2016-01-01

    Analysis of observations indicates that there was a rapid increase in summer (June-August, JJA) mean surface air temperature (SAT) since the mid-1990s over Western Europe. Accompanying this rapid warming are significant increases in summer mean daily maximum temperature, daily minimum temperature, annual hottest day temperature and warmest night temperature, and an increase in frequency of summer days and tropical nights, while the change in the diurnal temperature range (DTR) is small. This ...

  14. Dynamic fracture development in response to extreme summer temperatures: 27/7/2014, Långören Island, Finland

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    Leith, Kerry; Perras, Matthew; Siren, Topias; Rantanen, Tuomas; Heinonen, Suvi; Loew, Simon

    2017-04-01

    Long periods of exceptionally high temperatures in Finland and California during the summer of 2014 were associated with the formation of large 'exfoliation' or 'sheeting' fractures in bedrock surfaces. Videos taken at both locations show sharp fractures forming along the edge of thin (15,000 years ago), hinting at the rarity of the recent events on the otherwise undamaged surface. In order to uncover the mechanisms driving this remarkable event, we installed a unique low-cost monitoring system to track the behavior of the new Långören Island fracture through the summer of 2016. This included a local meteorological station, Arduino-based rock temperature profiles, acoustic emission measurements, and a 3G-enabled all-in-one PC for live data communication. Coupled with GPR data, field mapping, and a local DEM derived from a 'Go-Pro on a stick' structure from motion capture, we generate a unique insight into the conditions at the time of the 2014 event, and potential active micro-fracturing during a hot period in 2016. Our models suggest rock surface temperatures approached 40°C during 2014, almost ten degrees above the peak air temperature. The mid- to late-afternoon timing of fracturing was associated with peak thermal stress in the upper 1 m of bedrock, consistent with 2016 observations, where measured surface temperatures of around 35°C generate a thermal front that coincides with a series of acoustic emission events on a sensor installed in a borehole near the crest of the fracture.

  15. The Impact of Indian Ocean Variability on HighTemperature Extremes across the Southern Yangtze River Valley in Late Summer

    Institute of Scientific and Technical Information of China (English)

    HU Kaiming; HUANG Gang; QU Xia; HUANG Ronghui

    2012-01-01

    In this study,the teleconnection between Indian Ocean sea surface temperature anomalies (SSTAs) and the frequency of high temperature extremes (HTEs) across the southern Yangtze River valley (YRV) was investigated.The results indicate that the frequency of HTEs across the southern YRV in August is remotely influenced by the Indian Ocean basin mode (IOBM) SSTAs.Corresponding to June-July-August (JJA) IOBM warming condition,the number of HTEs was above normal,and corresponding to IOBM cooling conditions,the number of HTEs was below normal across the southern YRV in August.The results of this study indicate that the tropical IOBM warming triggered low-level anomalous anticyclonic circulation in the subtropical northwestern Pacific Ocean and southern China by emanating a warm Kelvin wave in August.In the southern YRV,the reduced rainfall and downward vertical motion associated with the anomalous low-level anticyclonic circulation led to the increase of HTE frequency in August.

  16. Summer 2015 Extremes over South Asia within the Historical Perspective

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    Rastogi, D.; Ashfaq, M.

    2015-12-01

    South Asian summer in 2015 has been marked by weather events of extremely different nature, including hot extremes over India and Pakistan, and wet extremes over northern, western and eastern states of India. Interestingly, these extremes are happening against the backdrop of warm sea surface temperature anomalies in the equatorial Pacific, which has historically reduced the strength of summer monsoon over South Asia. Given the occurrence of the contrasting anomalies at large and regional scales, in this study, we analyze 2015 extremes over South Asia within the historical perspective. We study the anomalies in the land, atmospheric and oceanic processes that potentially led to the regional heat waves and wet extremes throughout the summer and their connection to the large-scale anomalies in the monsoon dynamic. Additionally, we analyze historical simulations of the CMIP5 GCMs to investigate the likelihood of these anomalies with respect to the pre-industrial time period. Our analysis suggests evolving changes in the monsoon dynamics over South Asia where the lesser-known regional and local drivers have influence on the historical tele-connections.

  17. Aerosol forcing of extreme summer drought over North China

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    Zhang, Lixia; Wu, Peili; Zhou, Tianjun

    2017-03-01

    The frequency of extreme summer drought has been increasing in North China during the past sixty years, which has caused serious water shortages. It remains unclear whether anthropogenic forcing has contributed to the increasing extreme droughts. Using the National Centers for Environmental Prediction and the National Center for Atmospheric Research (NCEP/NCAR) re-analysis data and Coupled Model Intercomparison Project Phase 5 (CMIP5) model simulations with various combinations of historical forcings, the authors investigated the driving mechanism behind the observed changes. Metrological drought is usually measured by precipitation anomalies, which show lower fidelity in current climate models compared to large-scale circulation patterns. Based on NCEP/NCAR re-analysis, a linear relationship is firstly established between the weakest regional average 850 hPa southerly winds and extreme summer drought. This meridional winds index (MWI) is then used as a proxy for attribution of extreme North China drought using CMIP5 outputs. Examination of the CMIP5 simulations reveals that the probability of the extreme summer droughts with the first percentile of MWI for 1850–2004 under anthropogenic forcing has increased by 100%, on average, relative to a pre-industrial control run. The more frequent occurrence of extremely weak MWIs or drought over North China is ascribed from weakened climate and East Asian summer monsoon (EASM) circulation due to the direct cooling effect from increased aerosol.

  18. Changes in Extremely Hot Summers over the Global Land Area under Various Warming Targets.

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    Wang, Lei; Huang, Jianbin; Luo, Yong; Yao, Yao; Zhao, Zongci

    2015-01-01

    Summer temperature extremes over the global land area were investigated by comparing 26 models of the fifth phase of the Coupled Model Intercomparison Project (CMIP5) with observations from the Goddard Institute for Space Studies (GISS) and the Climate Research Unit (CRU). Monthly data of the observations and models were averaged for each season, and statistics were calculated for individual models before averaging them to obtain ensemble means. The summers with temperature anomalies (relative to 1951-1980) exceeding 3σ (σ is based on the local internal variability) are defined as "extremely hot". The models well reproduced the statistical characteristics evolution, and partly captured the spatial distributions of historical summer temperature extremes. If the global mean temperature increases 2°C relative to the pre-industrial level, "extremely hot" summers are projected to occur over nearly 40% of the land area (multi-model ensemble mean projection). Summers that exceed 5σ warming are projected to occur over approximately 10% of the global land area, which were rarely observed during the reference period. Scenarios reaching warming levels of 3°C to 5°C were also analyzed. After exceeding the 5°C warming target, "extremely hot" summers are projected to occur throughout the entire global land area, and summers that exceed 5σ warming would become common over 70% of the land area. In addition, the areas affected by "extremely hot" summers are expected to rapidly expand by more than 25%/°C as the global mean temperature increases by up to 3°C before slowing to less than 16%/°C as the temperature continues to increase by more than 3°C. The area that experiences summers with warming of 5σ or more above the warming target of 2°C is likely to maintain rapid expansion of greater than 17%/°C. To reduce the impacts and damage from severely hot summers, the global mean temperature increase should remain low.

  19. Changes in Extremely Hot Summers over the Global Land Area under Various Warming Targets.

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    Lei Wang

    Full Text Available Summer temperature extremes over the global land area were investigated by comparing 26 models of the fifth phase of the Coupled Model Intercomparison Project (CMIP5 with observations from the Goddard Institute for Space Studies (GISS and the Climate Research Unit (CRU. Monthly data of the observations and models were averaged for each season, and statistics were calculated for individual models before averaging them to obtain ensemble means. The summers with temperature anomalies (relative to 1951-1980 exceeding 3σ (σ is based on the local internal variability are defined as "extremely hot". The models well reproduced the statistical characteristics evolution, and partly captured the spatial distributions of historical summer temperature extremes. If the global mean temperature increases 2°C relative to the pre-industrial level, "extremely hot" summers are projected to occur over nearly 40% of the land area (multi-model ensemble mean projection. Summers that exceed 5σ warming are projected to occur over approximately 10% of the global land area, which were rarely observed during the reference period. Scenarios reaching warming levels of 3°C to 5°C were also analyzed. After exceeding the 5°C warming target, "extremely hot" summers are projected to occur throughout the entire global land area, and summers that exceed 5σ warming would become common over 70% of the land area. In addition, the areas affected by "extremely hot" summers are expected to rapidly expand by more than 25%/°C as the global mean temperature increases by up to 3°C before slowing to less than 16%/°C as the temperature continues to increase by more than 3°C. The area that experiences summers with warming of 5σ or more above the warming target of 2°C is likely to maintain rapid expansion of greater than 17%/°C. To reduce the impacts and damage from severely hot summers, the global mean temperature increase should remain low.

  20. Summer extreme precipitation in eastern China: mechanisms and impacts

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    Zhang, Qiang; Zheng, Yongjie; Singh, Vijay P.; Luo, Ming; Xie, Zhenghui

    2017-04-01

    changes and the related mechanisms are of great significance for regional management of water resources and agricultural irrigation. In this study, the impacts of western north Pacific subtropical high (WNPSH) on precipitation changes in eastern China and the underling processes are investigated. The results indicate that the strength and location of WNPSH are in close relations with the changes of summer precipitation in eastern China, and their influences vary across both space and time. In particular, WNPSH exerts remarkable impacts on precipitation in June and July in Jiang-Huai region and precipitation in June in South China such as the Pearl River basin. The inter-annual variations of WNPSH exhibits significant correlations with water vapor flux in East Asia and, and the variations of the location and direction of west flank of WNPSH is well corroborated that influences of East Asia summer monsoon on precipitation in eastern China. The westward extension of WNPSH tends to move the East Asian summer monsoon west and thus increasing water vapor flux in East Asia, which greatly benefits the occurrence of Meiyu regimes in Jiang-huai region. Besides, analysis results also show that the westward extension of WNPSH drives tropical cyclones sourthwards so as to increase the occurrence of extreme precipitation in South China. This study helps to bridge the knowledge gap in the relationship between WNPSH, tropical cyclones, summer precipitation events in eastern China.

  1. The role of increasing temperature variability in European summer heatwaves.

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    Schär, Christoph; Vidale, Pier Luigi; Lüthi, Daniel; Frei, Christoph; Häberli, Christian; Liniger, Mark A; Appenzeller, Christof

    2004-01-22

    Instrumental observations and reconstructions of global and hemispheric temperature evolution reveal a pronounced warming during the past approximately 150 years. One expression of this warming is the observed increase in the occurrence of heatwaves. Conceptually this increase is understood as a shift of the statistical distribution towards warmer temperatures, while changes in the width of the distribution are often considered small. Here we show that this framework fails to explain the record-breaking central European summer temperatures in 2003, although it is consistent with observations from previous years. We find that an event like that of summer 2003 is statistically extremely unlikely, even when the observed warming is taken into account. We propose that a regime with an increased variability of temperatures (in addition to increases in mean temperature) may be able to account for summer 2003. To test this proposal, we simulate possible future European climate with a regional climate model in a scenario with increased atmospheric greenhouse-gas concentrations, and find that temperature variability increases by up to 100%, with maximum changes in central and eastern Europe.

  2. A historical perspective of the extremely hot 2013 summer in East-central China

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    Liu, Qi; Fu, Congbin; Mao, Huiting

    2016-04-01

    An extreme hot summer occurred over East-central China in 2013. Its duration of continuous, highest temperature anomalies was the longest on record for the time period of 1948-2013. Several modeling studies have attempted to identify the causes and did not obtain conclusive findings, in large part due to their limited scopes of the problem. Here, we conducted a multi-scale and multi-factor analysis of this extreme event using observational data of 600 monitoring stations over China and global reanalysis data for the period of 1981-2013. Our results suggested that the number of heatwave days (NHD) (defined as a day with daily maximum temperature ≥ 35°C) over East-central China experienced an increasing trend of 3.44 days per decade since 1981 and reached the record maximum (34.1 days) in 2013, with significant inter-annual variability superimposed on the trend. It should be noted that this increasing trend in NHD was consistent with that of the intensity of the Western Pacific Subtropical High (WPSH) linked to global warming as suggested in the literature. There were also strong correlations between NHD over East-central China, WPSH, and global mean temperature (GT) on interannual scales. The extremely hot 2013 summer could not be explained by global warming and associated enhanced WPSH alone as GT and WPSH intensity were not record high in that summer. Further analysis suggested that large scale air-sea interaction over the Pacific region could have played a critical role. Specifically, enhanced convection over the Philippine Sea and along Indonesian islands in summer 2013 appeared to be strongest for the study period. This convection could cause a strong local feedback among precipitation, cloud cover, and net radiation, which could further weaken upper- and lower-level circulation via the tropical-extratropical teleconnection and Rossby wave propagation. This feedback was likely the direct cause of the extremely hot 2013 summer.

  3. Origin of extreme summers in Europe: the Indo-Pacific connection

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    Behera, Swadhin; Ratnam, Jayanthi V.; Masumoto, Yukio; Yamagata, Toshio

    2013-08-01

    Extreme summers of Europe are usually affected by blocking highs that shift between Western and Eastern Europe to cause regional variations in the surface temperature anomalies. Generally, the blocking high induces a regional temperature dipole with poles of warm and cold anomalies on two sides of Europe. The extreme summers of Western Europe, when the Eastern Europe is colder than normal, are usually associated with the teleconnections arising from positive Indian Ocean Dipole (IOD) events. In contrast, analogous warm events in Eastern Europe are usually associated with La Niña. The western Pacific conditions that prevail during the turnaround phase of El Niño to La Niña are found to be responsible for developing the extreme Eastern Europe events. The role of North Atlantic Oscillation (NAO) is not blatant for the Eastern Europe summers though it has a weaker influence on Western Europe summers for which IOD plays a dominant role: The seasonal July-August correlation for Western Europe temperature with IOD index is higher than that with the NAO index. The teleconnections for both types of extremes are associated with a Rossby wavetrain that travel around the globe to reach the Europe. This circumglobal teleconnection is largely determined by the location of the tropospheric heat source. For Western Europe warm events, major contributions come from the atmospheric convections/diabatic heating over northwest India and southern Pakistan. For the Eastern Europe events, the convections over northwest Pacific, south of Japan, are found to project the signals on to the mid-latitude wave-guide. These patterns of teleconnection are so robust that those can be seen on daily to seasonal time-scales of atmospheric anomalies. The wavetrains are found to set-in a couple of weeks prior to the development of blocking highs and extreme hot conditions over Europe.

  4. Predictability of summer extreme precipitation days over eastern China

    Science.gov (United States)

    Li, Juan; Wang, Bin

    2017-08-01

    Extreme precipitation events have severe impacts on human activity and natural environment, but prediction of extreme precipitation events remains a considerable challenge. The present study aims to explore the sources of predictability and to estimate the predictability of the summer extreme precipitation days (EPDs) over eastern China. Based on the region- and season-dependent variability of EPDs, all stations over eastern China are divided into two domains: South China (SC) and northern China (NC). Two domain-averaged EPDs indices during their local high EPDs seasons (May-June for SC and July-August for NC) are therefore defined. The simultaneous lower boundary anomalies associated with each EPDs index are examined, and we find: (a) the increased EPDs over SC are related to a rapid decaying El Nino and controlled by Philippine Sea anticyclone anomalies in May-June; (b) the increased EPDs over NC are accompanied by a developing La Nina and anomalous zonal sea level pressure contrast between the western North Pacific subtropical high and East Asian low in July-August. Tracking back the origins of these boundary anomalies, one or two physically meaningful predictors are detected for each regional EPDs index. The causative relationships between the predictors and the corresponding EPDs over each region are discussed using lead-lag correlation analyses. Using these selected predictors, a set of Physics-based Empirical models is derived. The 13-year (2001-2013) independent forecast shows significant temporal correlation skills of 0.60 and 0.74 for the EPDs index of SC and NC, respectively, providing an estimation of the predictability for summer EPDs over eastern China.

  5. Forecasting extreme temperature health hazards in Europe

    Science.gov (United States)

    Di Napoli, Claudia; Pappenberger, Florian; Cloke, Hannah L.

    2017-04-01

    Extreme hot temperatures, such as those experienced during a heat wave, represent a dangerous meteorological hazard to human health. Heat disorders such as sunstroke are harmful to people of all ages and responsible for excess mortality in the affected areas. In 2003 more than 50,000 people died in western and southern Europe because of a severe and sustained episode of summer heat [1]. Furthermore, according to the Intergovernmental Panel on Climate Change heat waves are expected to get more frequent in the future thus posing an increasing threat to human lives. Developing appropriate tools for extreme hot temperatures prediction is therefore mandatory to increase public preparedness and mitigate heat-induced impacts. A recent study has shown that forecasts of the Universal Thermal Climate Index (UTCI) provide a valid overview of extreme temperature health hazards on a global scale [2]. UTCI is a parameter related to the temperature of the human body and its regulatory responses to the surrounding atmospheric environment. UTCI is calculated using an advanced thermo-physiological model that includes the human heat budget, physiology and clothing. To forecast UTCI the model uses meteorological inputs, such as 2m air temperature, 2m water vapour pressure and wind velocity at body height derived from 10m wind speed, from NWP models. Here we examine the potential of UTCI as an extreme hot temperature prediction tool for the European area. UTCI forecasts calculated using above-mentioned parameters from ECMWF models are presented. The skill in predicting UTCI for medium lead times is also analysed and discussed for implementation to international health-hazard warning systems. This research is supported by the ANYWHERE project (EnhANcing emergencY management and response to extreme WeatHER and climate Events) which is funded by the European Commission's HORIZON2020 programme. [1] Koppe C. et al., Heat waves: risks and responses. World Health Organization. Health and

  6. Climate Drivers of Alaska Summer Stream Temperature

    Science.gov (United States)

    Bieniek, P.; Bhatt, U. S.; Plumb, E. W.; Thoman, R.; Trammell, E. J.

    2016-12-01

    The temperature of the water in lakes, rivers and streams has wide ranging impacts from local water quality and fish habitats to global climate change. Salmon fisheries in Alaska, a critical source of food in many subsistence communities, are sensitive to large-scale climate variability and river and stream temperatures have also been linked with salmon production in Alaska. Given current and projected climate change, understanding the mechanisms that link the large-scale climate and river and stream temperatures is essential to better understand the changes that may occur with aquatic life in Alaska's waterways on which subsistence users depend. An analysis of Alaska stream temperatures in the context of reanalysis, downscaled, station and other climate data is undertaken in this study to fill that need. Preliminary analysis identified eight stream observation sites with sufficiently long (>15 years) data available for climate-scale analysis in Alaska with one station, Terror Creek in Kodiak, having a 30-year record. Cross-correlation of summer (June-August) water temperatures between the stations are generally high even though they are spread over a large geographic region. Correlation analysis of the Terror Creek summer observations with seasonal sea surface temperatures (SSTs) in the North Pacific broadly resembles the SST anomaly fields typically associated with the Pacific Decadal Oscillation (PDO). A similar result was found for the remaining stations and in both cases PDO-like correlation patterns also occurred in the preceding spring. These preliminary results demonstrate that there is potential to diagnose the mechanisms that link the large-scale climate system and Alaska stream temperatures.

  7. Mechanisms underlying temperature extremes in Iberia: a Lagrangian perspective

    Directory of Open Access Journals (Sweden)

    João A. Santos

    2015-04-01

    Full Text Available The mechanisms underlying the occurrence of temperature extremes in Iberia are analysed considering a Lagrangian perspective of the atmospheric flow, using 6-hourly ERA-Interim reanalysis data for the years 1979–2012. Daily 2-m minimum temperatures below the 1st percentile and 2-m maximum temperatures above the 99th percentile at each grid point over Iberia are selected separately for winter and summer. Four categories of extremes are analysed using 10-d backward trajectories initialized at the extreme temperature grid points close to the surface: winter cold (WCE and warm extremes (WWE, and summer cold (SCE and warm extremes (SWE. Air masses leading to temperature extremes are first transported from the North Atlantic towards Europe for all categories. While there is a clear relation to large-scale circulation patterns in winter, the Iberian thermal low is important in summer. Along the trajectories, air mass characteristics are significantly modified through adiabatic warming (air parcel descent, upper-air radiative cooling and near-surface warming (surface heat fluxes and radiation. High residence times over continental areas, such as over northern-central Europe for WCE and, to a lesser extent, over Iberia for SWE, significantly enhance these air mass modifications. Near-surface diabatic warming is particularly striking for SWE. WCE and SWE are responsible for the most extreme conditions in a given year. For WWE and SCE, strong temperature advection associated with important meridional air mass transports are the main driving mechanisms, accompanied by comparatively minor changes in the air mass properties. These results permit a better understanding of mechanisms leading to temperature extremes in Iberia.

  8. Extreme summer heat in Phoenix, Arizona (USA under global climate change (2041-2070

    Directory of Open Access Journals (Sweden)

    Grossman-Clarke, Susanne

    2014-09-01

    Full Text Available Summer extreme heat events in the arid Phoenix, Arizona (USA metropolitan region for the period 2041-2070 are projected based on the ensemble of ten climate models from the North American Regional Climate Change Assessment Program for the SRES A2 greenhouse gas emissions scenario by the Intergovernmental Panel on Climate Change. Extreme heat events are identified by measures related to two thresholds of the maximum daily air temperature distribution for the historical reference period 1971-2000. Comparing this reference period to the model ensemble-mean, the frequency of extreme heat events is projected to increase by a factor of six to 1.9 events per summer and the average number of event days per year is projected to increase by a factor of 14. The inter-model range for the average number of EHE days per summer is larger for the projected climate, 10.6 to 42.2 days, than for simulations of the past climate simulations (1.5 to 2.4 days.

  9. Robust increase in extreme summer rainfall intensity during the past four decades observed in China

    Science.gov (United States)

    Xiao, Chan; Wu, Peili; Zhang, Lixia; Song, Lianchun

    2016-12-01

    Global warming increases the moisture holding capacity of the atmosphere and consequently the potential risks of extreme rainfall. Here we show that maximum hourly summer rainfall intensity has increased by about 11.2% on average, using continuous hourly gauge records for 1971–2013 from 721 weather stations in China. The corresponding event accumulated precipitation has on average increased by more than 10% aided by a small positive trend in events duration. Linear regression of the 95th percentile daily precipitation intensity with daily mean surface air temperature shows a negative scaling of ‑9.6%/K, in contrast to a positive scaling of 10.6%/K for hourly data. This is made up of a positive scaling below the summer mean temperature and a negative scaling above. Using seasonal means instead of daily means, we find a consistent scaling rate for the region of 6.7–7%/K for both daily and hourly precipitation extremes, about 10% higher than the regional Clausius-Clapeyron scaling of 6.1%/K based on a mean temperature of 24.6 °C. With up to 18% further increase in extreme precipitation under continuing global warming towards the IPCC’s 1.5 °C target, risks of flash floods will exacerbate on top of the current incapability of urban drainage systems in a rapidly urbanizing China.

  10. Links between Arctic sea ice and extreme summer precipi- tation in China:an alternative view

    Institute of Scientific and Technical Information of China (English)

    Petteri Uotila; Alexey Karpechko; Timo Vihma

    2014-01-01

    Potential links between the Arctic sea-ice concentration anomalies and extreme precipitation in China are explored. Associations behind these links can be explained by physical interpretations aided by visualisations of temporarily lagged composites of variables such as atmospheric mean sea level pressure and sea surface temperature. This relatively simple approach is veriifed by collectively examining already known links between the Arctic sea ice and rainfall in China. For example, similarities in the extreme summer rainfall response to Arctic sea-ice concentration anomalies either in winter (DJF) or in spring (MAM) are highlighted. Furthermore, new links between the Arctic sea ice and the extreme weather in India and Eurasia are proposed. The methodology developed in this study can be further applied to identify other remote impacts of the Arctic sea ice variability.

  11. New algorithm for extreme temperature measurements

    NARCIS (Netherlands)

    Damean, N.

    2000-01-01

    A new algorithm for measurement of extreme temperature is presented. This algorithm reduces the measurement of the unknown temperature to the solving of an optimal control problem, using a numerical computer. Based on this method, a new device for extreme temperature measurements is projected. It co

  12. Operational forecasting of daily temperatures in the Valencia Region. Part I: maximum temperatures in summer.

    Science.gov (United States)

    Gómez, I.; Estrela, M.

    2009-09-01

    Extreme temperature events have a great impact on human society. Knowledge of summer maximum temperatures is very useful for both the general public and organisations whose workers have to operate in the open, e.g. railways, roadways, tourism, etc. Moreover, summer maximum daily temperatures are considered a parameter of interest and concern since persistent heat-waves can affect areas as diverse as public health, energy consumption, etc. Thus, an accurate forecasting of these temperatures could help to predict heat-wave conditions and permit the implementation of strategies aimed at minimizing the negative effects that high temperatures have on human health. The aim of this work is to evaluate the skill of the RAMS model in determining daily maximum temperatures during summer over the Valencia Region. For this, we have used the real-time configuration of this model currently running at the CEAM Foundation. To carry out the model verification process, we have analysed not only the global behaviour of the model for the whole Valencia Region, but also its behaviour for the individual stations distributed within this area. The study has been performed for the summer forecast period of 1 June - 30 September, 2007. The results obtained are encouraging and indicate a good agreement between the observed and simulated maximum temperatures. Moreover, the model captures quite well the temperatures in the extreme heat episodes. Acknowledgement. This work was supported by "GRACCIE" (CSD2007-00067, Programa Consolider-Ingenio 2010), by the Spanish Ministerio de Educación y Ciencia, contract number CGL2005-03386/CLI, and by the Regional Government of Valencia Conselleria de Sanitat, contract "Simulación de las olas de calor e invasiones de frío y su regionalización en la Comunidad Valenciana" ("Heat wave and cold invasion simulation and their regionalization at Valencia Region"). The CEAM Foundation is supported by the Generalitat Valenciana and BANCAIXA (Valencia, Spain).

  13. Multivariate Regression Analysis and Statistical Modeling for Summer Extreme Precipitation over the Yangtze River Basin, China

    Directory of Open Access Journals (Sweden)

    Tao Gao

    2014-01-01

    Full Text Available Extreme precipitation is likely to be one of the most severe meteorological disasters in China; however, studies on the physical factors affecting precipitation extremes and corresponding prediction models are not accurately available. From a new point of view, the sensible heat flux (SHF and latent heat flux (LHF, which have significant impacts on summer extreme rainfall in Yangtze River basin (YRB, have been quantified and then selections of the impact factors are conducted. Firstly, a regional extreme precipitation index was applied to determine Regions of Significant Correlation (RSC by analyzing spatial distribution of correlation coefficients between this index and SHF, LHF, and sea surface temperature (SST on global ocean scale; then the time series of SHF, LHF, and SST in RSCs during 1967–2010 were selected. Furthermore, other factors that significantly affect variations in precipitation extremes over YRB were also selected. The methods of multiple stepwise regression and leave-one-out cross-validation (LOOCV were utilized to analyze and test influencing factors and statistical prediction model. The correlation coefficient between observed regional extreme index and model simulation result is 0.85, with significant level at 99%. This suggested that the forecast skill was acceptable although many aspects of the prediction model should be improved.

  14. Extreme temperatures and precipitation in Poland. An evaluation attempt

    Energy Technology Data Exchange (ETDEWEB)

    Ustrnul, Zbigniew [Institute of Meteorology and Water Management, Krakow (Poland); Wypych, Agnieszka; Kosowski, Marek [Jagiellonian Univ., Krakow (Poland)

    2012-02-15

    Summer (JJA) and winter (DJF) temperature extremes and summer (JJA) precipitation extremes in Poland that occurred in the years 1951-2006 are analyzed in this paper. Diurnal extreme values of air temperature (Tmax, Tmin) and diurnal precipitation totals (P) are considered. The data was obtained from 54 meteorological stations. Extreme values were identified based on different methodological approaches. Advantages and disadvantages of selected methods are shown with respect to both temporal and spatial variability of the data. The differences obtained as a result of the applied criteria confirm that the method of percentiles seems to be the most suitable one to be used in spatial analysis. This is especially relevant in areas with a relatively high variability of absolute values. When it comes to analyses of multi-annual trends, the criterion used plays a less significant role. Regardless of the method, there is a certain direction of changes that is maintained, although their magnitudes may be different. It may be concluded from the conducted analyses that for the full evaluation of both spatial variability and temporal variability of weather extremes, a variety of methods and criteria for identifying extreme values, should be considered. They may significantly influence the final results. (orig.)

  15. Coaxial Cables for Martian Extreme Temperature Environments

    Science.gov (United States)

    Ramesham, Rajeshuni; Harvey, Wayne L.; Valas, Sam; Tsai, Michael C.

    2011-01-01

    Work was conducted to validate the use of the rover external flexible coaxial cabling for space under the extreme environments to be encountered during the Mars Science Laboratory (MSL) mission. The antennas must survive all ground operations plus the nominal 670-Martian-day mission that includes summer and winter seasons of the Mars environment. Successful development of processes established coaxial cable hardware fatigue limits, which were well beyond the expected in-flight exposures. In keeping with traditional qualification philosophy, this was accomplished by subjecting flight-representative coaxial cables to temperature cycling of the same depth as expected in-flight, but for three times the expected number of in-flight thermal cycles. Insertion loss and return loss tests were performed on the coaxial cables during the thermal chamber breaks. A vector network analyzer was calibrated and operated over the operational frequency range 7.145 to 8.450 GHz. Even though some of the exposed cables function only at UHF frequencies (approximately 400 MHz), the testing was more sensitive, and extending the test range down to 400 MHz would have cost frequency resolution. The Gore flexible coaxial cables, which were the subject of these tests, proved to be robust and displayed no sign of degradation due to the 3X exposure to the punishing Mars surface operations cycles.

  16. Impact of soil moisture on extreme maximum temperatures in Europe

    Directory of Open Access Journals (Sweden)

    Kirien Whan

    2015-09-01

    Full Text Available Land-atmosphere interactions play an important role for hot temperature extremes in Europe. Dry soils may amplify such extremes through feedbacks with evapotranspiration. While previous observational studies generally focused on the relationship between precipitation deficits and the number of hot days, we investigate here the influence of soil moisture (SM on summer monthly maximum temperatures (TXx using water balance model-based SM estimates (driven with observations and temperature observations. Generalized extreme value distributions are fitted to TXx using SM as a covariate. We identify a negative relationship between SM and TXx, whereby a 100 mm decrease in model-based SM is associated with a 1.6 °C increase in TXx in Southern-Central and Southeastern Europe. Dry SM conditions result in a 2–4 °C increase in the 20-year return value of TXx compared to wet conditions in these two regions. In contrast with SM impacts on the number of hot days (NHD, where low and high surface-moisture conditions lead to different variability, we find a mostly linear dependency of the 20-year return value on surface-moisture conditions. We attribute this difference to the non-linear relationship between TXx and NHD that stems from the threshold-based calculation of NHD. Furthermore the employed SM data and the Standardized Precipitation Index (SPI are only weakly correlated in the investigated regions, highlighting the importance of evapotranspiration and runoff for resulting SM. Finally, in a case study for the hot 2003 summer we illustrate that if 2003 spring conditions in Southern-Central Europe had been as dry as in the more recent 2011 event, temperature extremes in summer would have been higher by about 1 °C, further enhancing the already extreme conditions which prevailed in that year.

  17. Mechanisms for Amplified Central European Summer Precipitation Extremes in a Warmer Mediterranean Climate

    Science.gov (United States)

    Volosciuk, Claudia; Maraun, Douglas; Semenov, Vladimir; Tilinina, Natalia; Latif, Mojib

    2015-04-01

    Central European climate is influenced by the Mediterranean Sea, where a strong increase in sea surface temperature (SST) has been observed during the last four decades. One example of extreme weather events are cyclones following the "Vb" pathway. These cyclones are generated over the Mediterranean Sea, travel northeastwards around the Alps and then hit central European countries. These cyclones carry large amounts of moisture and cause extreme precipitation, and subsequently flooding, particularly in summer. To investigate the mechanisms causing increased summer extreme precipitation due to increased Mediterranean SST in Europe, we analyze a series of simulations with the atmospheric general circulation model ECHAM5. In the control run, we forced the model with the 1970-1999 SST climatology. In an additional run, we replaced the Mediterranean and Black Sea SST forcing with the climatology of the warmer 2000-2012 period. ECHAM5 was run at high horizontal resolution (T159) and integrated for 40 years in each experiment. 20-season return levels were derived as a measure of extreme precipitation for daily precipitation in JJA (June - August). These return levels are estimated as quantiles of a stationary generalized Pareto distribution, based on exceedances of the 95th precipitation percentile. We have shown in a previous contribution that precipitation return levels in JJA increase along the Vb cyclone track although the number of Vb cyclones does not increase. Here we discuss the mechanisms responsible for this increase. Due to the warmer climate in the Mediterranean region, climatological mean evaporation and precipitable water in the atmosphere are increased. On extreme days, composites show an even further increase in precipitable water over the central European region. On these extreme days, a higher sea level pressure gradient between central Europe and the Atlantic causes enhanced cyclonic flow that transports more moisture from the Mediterranean region to

  18. Betavoltaic performance under extreme temperatures

    Directory of Open Access Journals (Sweden)

    Adams Tom

    2016-01-01

    Full Text Available Longevity of sensors and portable devices is severely limited by temperature, chemical instability, and electrolyte leakage issues associated with conventional electrochemical batteries. Betavoltaics, which operate similar to photo voltaics, can operate in a wide temperature range safely without permanent degradation. Though not a new concept, which began in the 1950's and peaked in the mid 1970's, research has been minimal and sporadic until recent advancements in ultra-low power electronics and materialization of low power applications. The technology is rapidly maturing, generating research, and development in increasing the beta emitting source and semiconductor efficiencies. This study presents an update on betavoltaic technology, results from temperature evaluation on commercially available General Licensed betavoltaic cells, development of a hybrid system for latent and burst power, modeling and simulation techniques and results, and current and proposed research and development. Betavoltaic performance was successfully demonstrated for a wide temperature range (-30°C to 70°C. Short circuit current and open circuit voltage were used to compare electrical performance. Results indicate that the open-circuit voltage and maximum power decreased as temperature increased due to increases in the semiconductor's intrinsic carrier concentration.

  19. Observed variability of summer precipitation pattern and extreme events in East China associated with variations of the East Asian summer monsoon: VARIABILITY OF SUMMER PRECIPITATION AND EXTREME EVENT IN EAST CHINA

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lei [School of Atmospheric Sciences, Nanjing University, China; Pacific Northwest National Laboratory, Richland WA USA; Qian, Yun [Pacific Northwest National Laboratory, Richland WA USA; Zhang, Yaocun [School of Atmospheric Sciences, Nanjing University, China; Zhao, Chun [Pacific Northwest National Laboratory, Richland WA USA; Leung, L. Ruby [Pacific Northwest National Laboratory, Richland WA USA; Huang, Anning [School of Atmospheric Sciences, Nanjing University, China; Xiao, Chuliang [Cooperative Institute for Limnology and Ecosystems Research, School of Natural Resources and Environment, University of Michigan, Ann Arbor MI USA

    2015-11-09

    This paper presents a comprehensive analysis of interannual and interdecadal variations of summer precipitation and precipitation-related extreme events in China associated with variations of the East Asian summer monsoon (EASM) from 1979-2012. A high-quality daily precipitation dataset covering 2287 weather stations in China is analyzed. Based on the precipitation pattern analysis using empirical orthogonal functions, three sub-periods of 1979-1992 (period I), 1993-1999 (period II) and 2000-2012 (period III) are identified to be representative of the precipitation variability. Similar significant variability of the extreme precipitation indices is found across four sub-regions in eastern China. The spatial patterns of summer mean precipitation, the number of days with daily rainfall exceeding 95th percentile precipitation (R95p) and the maximum number of consecutive wet days (CWD) anomalies are consistent, but opposite to that of maximum consecutive dry days (CDD) anomalies during the three sub-periods. However, the spatial patterns of hydroclimatic intensity (HY-INT) are notably different from that of the other three extreme indices, but highly correlated to the dry events. The changes of precipitation anomaly patterns are accompanied by the change of the EASM regime and the abrupt shift of the position of the west Pacific subtropical high around 1992/1993 and 1999/2000, respectively, which influence the moisture transport that contributes most to the precipitation anomalies. Lastly, the EASM intensity is linked to sea surface temperature anomaly over the tropical Indian and Pacific Ocean that influences deep convection over the oceans.

  20. Extreme Environment High Temperature Communication Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The purpose of this project is to develop and demonstrate a communications system capable of operation at extreme temperatures and pressures in hostile and corrosive...

  1. Flexible diaphragm-extreme temperature usage

    Science.gov (United States)

    Lerma, Guillermo (Inventor)

    1991-01-01

    A diaphragm suitable for extreme temperature usage, such as encountered in critical aerospace applications, is fabricated by a unique method, and of a unique combination of materials. The materials include multilayered lay-ups of diaphragm materials sandwiched between layers of bleeder fabrics. After being formed in the desired shape on a mold, they are vacuum sealed and then cured under pressure, in a heated autoclave. A bond capable of withstanding extreme temperatures are produced.

  2. Summer temperatures across northern North America: Regional reconstructions from 1760 using tree-ring densities

    Science.gov (United States)

    Briffa, K. R.; Jones, P. D.; Schweingruber, F. H.

    1994-12-01

    Using maximum latewood density data from a network of coniferous trees, annually resolved series of average summer half-year (April-September) temperatures have been reconstructed for three regions of North America: Alaska and the Yukon (ALAYUK), the Mackenzie valley (MACKVA), and Quebec and Labrador (QUEBLA). The reconstructions primarily express temperature variability on interannual-to-decadal timescales and extend over the period from AD 1760. These reconstructions represent an extension of the mean climate history for these regions of over 100 years. The ALAYUK series shows relatively wann summers dominating the 1770s and 1820s. The 1760s, 1810s, 1860s, and 1890s were cold; 1810 was the coldest summer over the whole region, though it was very cold in 1783 in the extreme northwest. In MACKVA the 1780s and 1790s were warm, while the 1810s, 1830s, and late 1880s were cool. The summer of 1862 was exceptionally warm and 1836 was notably cold. In QUEBLA the 1800s, 1820s, and late 1890s were relatively warm, while the 1760s and 1810s were particularly cool. The summers of 1816 and 1817 were extremely cold. The dates of the extreme cold summers in each series emphasize the strong volcanic influence on extreme high-latitude temperatures. However, the reconstructions also highlight the large regional differences in the magnitude of this influence. The severity and spatial extent of severe conditions across western North America in the summer of 1810 supports earlier hypotheses of a major volcanic eruption in 1809 for which there is no historical evidence.

  3. Photosynthetic response of Persian Gulf acroporid corals to summer versus winter temperature deviations

    Directory of Open Access Journals (Sweden)

    Jahangir Vajed Samiei

    2015-06-01

    Full Text Available With on-going climate change, coral susceptibility to thermal stress constitutes a central concern in reefconservation. In the Persian Gulf, coral reefs are confronted with a high seasonal variability in water temperature, and both hot and cold extremes have been associated with episodes of coral bleaching and mortality. Using physiological performance as a measure of coral health, we investigated the thermal susceptibility of the common acroporid, Acropora downingi, near Hengam Island where the temperature oscillates seasonally in the range 20.2–34.2 °C. In a series of two short-term experiments comparing coral response in summer versus winter conditions, we exposed corals during each season (1 to the corresponding seasonal average and extreme temperature levels in a static thermal environment, and (2 to a progressive temperature deviation from the annual mean toward the corresponding extreme seasonal value and beyond in a dynamic thermal environment. We monitored four indictors of coral physiological performance: net photosynthesis (Pn, dark respiration (R, autotrophic capability (Pn/R, and survival. Corals exposed to warming during summer showed a decrease in net photosynthesis and ultimately died, while corals exposed to cooling during winter were not affected in their photosynthetic performance and survival. Coral autotrophic capability Pn/R was lower at the warmer thermal level within eachseason, and during summer compared to winter. Corals exposed to the maximum temperature of summer displayed Pn/R < 1, inferring that photosynthetic performance could not support basal metabolic needs under this environment. Our results suggest that the autotrophic performance of the Persian Gulf A. downingi is sensitive to the extreme temperatures endured in summer, and therefore its populations may be impacted by future increases in water temperature.

  4. LHC Report: Summer temperatures in the LHC

    CERN Multimedia

    Jan Uythoven for the LHC Team

    2012-01-01

    The LHC experiments have finished their data-taking period before the summer conferences. The machine has already delivered substantially more collisions to the experiments this year than in the whole of 2011. The LHC has now started a six-day Machine Development period, which will be followed by the second Technical Stop of the year.   The number of collisions delivered to the experiments is expressed in integrated luminosity. In 2011, the integrated luminosity delivered to both ATLAS and CMS was around 5.6 fb-1. On Monday 18 June, experiments finished taking data before the summer conferences and the integrated luminosity for 2012 so far is about 6.6 fb-1, well above the unofficial target of 5 fb-1. The LHC’s performance over the last week of running was so efficient that the injection kicker magnets – which heat up due to the circulating beam – did not have time to cool down between the subsequent fills. As the time constants for warming up and cooli...

  5. Quantitative risk assessment of the effects of drought on extreme temperature in eastern China

    Science.gov (United States)

    Hao, Zengchao; Hao, Fanghua; Singh, Vijay P.; Ouyang, Wei

    2017-09-01

    Hot extremes may lead to disastrous impacts on human health and agricultural production. Previous studies have revealed the feedback between drought and hot extremes in large regions of eastern China, while quantifying the impact of antecedent drought on hot extremes has been limited. This study aims at quantitatively assessing the risk of extreme temperature conditioned on the antecedent drought condition represented by Standardized Precipitation Index (SPI) during summer time in eastern China. A copula-based model is proposed to construct the joint probability distribution of extreme temperature and drought based on 6 month SPI (SPI6). Accordingly, the conditional probability distribution is employed to quantify impacts of antecedent dry (and wet) conditions on the exceedance probability of extreme temperature. Results show that the likelihood of extreme temperature exceeding high quantiles is higher given antecedent dry conditions than that given antecedent wet conditions in large regions from southwestern to northeastern China. Specifically, the conditional probability difference of temperature exceeding 80th percentile given SPI6 lower than or equal to -0.5 and SPI6 higher than 0.5 is around 0.2-0.3. The case study of the 2006 summer hot extremes and drought in Sichuan and Chongqing region shows that the conditional return period of extreme temperature conditioned on antecedent drought is around 5-50 years shorter than univariate return period. These results quantify the impact of antecedent drought on subsequent extreme temperature and highlight the important role of antecedent drought in intensifying hot extremes in these regions.

  6. Extreme Heat Wave over European Russia in Summer 2010: Anomaly or a Manifestation of Climatic Trend?

    Science.gov (United States)

    Razuvaev, V.; Groisman, P. Y.; Bulygina, O.; Borzenkova, I.

    2010-12-01

    Extraordinary temperature anomalies over European Russia (ER) in summer 2010 raised a legitimate question in the title of this presentation. A 60-days-long hot anticyclonic weather system with daily temperature anomalies as high as +10K and no or negligible amount of rainfall first decimated crops in the forest-steppe zone of ER, gradually dried wetlands in the forest zone and, finally, caused numerous natural and anthropogenic fires that at the time of this abstract preparation have not yet been extinguished. The extreme heat, lack of precipitation, and forest fires have caused hundreds of deaths and multimillion dollars in property losses. Indirect losses of lives due to this weather anomaly, with the ensuing fires and related air pollution, as well as the absence of air conditioning in apartments has yet to be estimated. The center of European Russia was well covered by meteorological observations for the past 130 years. These data, historical weather records (yearbooks or "letopisi" , which were carried on in the major Russian monasteries), and finally, dendroclimatological information, all show that this summer temperature anomaly was well above all known extremes in the past 1000 years. Like ocean waves and ocean tides, weather and climate variability go together strengthening (or mitigating) each other. We shall show the precursors of the current outbreak using principally the most accurate meteorological records of the past century updated to 2009 (at the Session, the 2010 data will also be presented). While a careful analyses of these records and thoughtful analyses of recent similar temperature outbreaks in Western Europe could not prevent the occurrence of this disaster, the lessons learned from these analyses (a) would warn about its increasing probability and (b) mitigation and adaptation measures could well be made to reduce its negative consequences. Among our arguments are: (1)There is a century-long tendency of reduction of equator minus pole

  7. Atlantic Multi-decadal Oscillation and changes of summer air temperature in Montenegro

    Directory of Open Access Journals (Sweden)

    Doderovic Miroslav M.

    2015-01-01

    Full Text Available The paper has examined the impact of variations of Atlantic Multidecadal Oscillation (AMO on the change in air temperature during the summer season on the territory of Montenegro. Starting from the fact that in recent years more and more extreme weather events occur, as well as from the intention to comprehensively consider the temperature conditions in the territory of Montenegro, first analysis is of changes in air temperature in 8 parameters, of which 5 climate indices; connections with AMO have also been analyzed. To study changes in temperature extreme indexes proposed by the WMO CCL / CLIVAR are used. Research within the listed topics was realized using data from 23 meteorological stations for the period 1951-2010 and the calculations are done for the summer season. The results show that there is increased number of maximum and minimum daily temperatures of warmer value. Impact assessment AMO, teleconnection pattern that is quite distant, showed that its variability affects changes in summer temperatures in Montenegro, both in terms of mean values, and the frequency of extreme actions presented by climate indices.

  8. Multiple perspectives on the attribution of the extreme European summer of 2012 to climate change

    Science.gov (United States)

    Wilcox, Laura J.; Yiou, Pascal; Hauser, Mathias; Lott, Fraser C.; van Oldenborgh, Geert Jan; Colfescu, Ioana; Dong, Buwen; Hegerl, Gabi; Shaffrey, Len; Sutton, Rowan

    2017-07-01

    Summer 2012 was very wet in northern Europe, and unusually dry and hot in southern Europe. We use multiple approaches to determine whether anthropogenic forcing made the extreme European summer of 2012 more likely. Using a number of observation- and model-based methods, we find that there was an anthropogenic contribution to the extremes in southern Europe, with a qualitative consensus across all methodologies. There was a consensus across the methodologies that there has been a significant increase in the risk of hot summers in southern Europe with climate change. Most approaches also suggested a slight drying, but none of the results were statistically significant. The unusually wet summer in northern Europe was made more likely by the observed atmospheric circulation pattern in 2012, but no evidence was found for a long-term trend in circulation.

  9. Contrasting and interacting changes in simulated spring and summer carbon cycle extremes in European ecosystems

    Science.gov (United States)

    Sippel, Sebastian; Forkel, Matthias; Rammig, Anja; Thonicke, Kirsten; Flach, Milan; Heimann, Martin; Otto, Friederike E. L.; Reichstein, Markus; Mahecha, Miguel D.

    2017-07-01

    Climate extremes have the potential to cause extreme responses of terrestrial ecosystem functioning. However, it is neither straightforward to quantify and predict extreme ecosystem responses, nor to attribute these responses to specific climate drivers. Here, we construct a factorial experiment based on a large ensemble of process-oriented ecosystem model simulations driven by a regional climate model (12 500 model years in 1985-2010) in six European regions. Our aims are to (1) attribute changes in the intensity and frequency of simulated ecosystem productivity extremes (EPEs) to recent changes in climate extremes, CO2 concentration, and land use, and to (2) assess the effect of timing and seasonal interaction on the intensity of EPEs. Evaluating the ensemble simulations reveals that (1) recent trends in EPEs are seasonally contrasting: spring EPEs show consistent trends towards increased carbon uptake, while trends in summer EPEs are predominantly negative in net ecosystem productivity (i.e. higher net carbon release under drought and heat in summer) and close-to-neutral in gross productivity. While changes in climate and its extremes (mainly warming) and changes in CO2 increase spring productivity, changes in climate extremes decrease summer productivity neutralizing positive effects of CO2. Furthermore, we find that (2) drought or heat wave induced carbon losses in summer (i.e. negative EPEs) can be partly compensated by a higher uptake in the preceding spring in temperate regions. Conversely, however, carry-over effects from spring to summer that arise from depleted soil moisture exacerbate the carbon losses caused by climate extremes in summer, and are thus undoing spring compensatory effects. While the spring-compensation effect is increasing over time, the carry-over effect shows no trend between 1985-2010. The ensemble ecosystem model simulations provide a process-based interpretation and generalization for spring-summer interacting carbon cycle effects

  10. Modest summer temperature variability during DO cycles in western Europe

    Science.gov (United States)

    Ampel, Linda; Bigler, Christian; Wohlfarth, Barbara; Risberg, Jan; Lotter, André F.; Veres, Daniel

    2010-06-01

    Abrupt climatic shifts between cold stadials and warm interstadials, termed Dansgaard-Oeschger (DO) cycles, occurred frequently during the Last Glacial. Their imprint is registered in paleorecords worldwide, but little is known about the actual temperature change both annually and seasonally in different regions. A recent hypothesis based on modelling studies, suggests that DO cycles were characterised by distinct changes in seasonality in the Northern Hemisphere. The largest temperature change between stadial and interstadial phases would have occurred during the winter and spring seasons, whereas the summer seasons would have experienced a rather muted temperature shift. Here we present a temporally high-resolved reconstruction of summer temperatures for eastern France during a sequence of DO cycles between 36 and 18 thousand years before present. The reconstruction is based on fossil diatom assemblages from the paleolake Les Echets and indicates summer temperature changes of ca 0.5-2 °C between stadials and interstadials. This study is the first to reconstruct temperatures with a sufficient time resolution to investigate DO climate variability in continental Europe. It is therefore also the first proxy record that can test and support the hypothesis that temperature changes during DO cycles were modest during the summer season.

  11. Relativistic QED Plasma at Extremely High Temperature

    CERN Document Server

    Masood, Samina S

    2016-01-01

    Renormalization scheme of QED (Quantum Electrodynamics) at high temperatures is used to calculate the effective parameters of relativistic plasma in the early universe. Renormalization constants of QED play role of effective parameters of the theory and can be used to determine the collective behavior of the medium. We explicitly show that the dielectric constant, magnetic reluctivity, Debye length and the plasma frequency depend on temperature in the early universe. Propagation speed, refractive index, plasma frequency and Debye shielding length of a QED plasma are computed at extremely high temperatures in the early universe. We also found the favorable conditions for the relativistic plasma from this calculations.

  12. 气候变暖背景下2015年夏季新疆极端高温过程及其影响%Characteristics and effects of the extreme maximum air temperature in the summer of 2015 in Xinjiang under global warming

    Institute of Scientific and Technical Information of China (English)

    毛炜峄; 陈鹏翔; 沈永平

    2016-01-01

    用新疆105个气象站监测资料,分析了2015年夏季高温过程的极端特征.2015年夏季新疆区域出现高温过程,从7月上旬后期开始,南疆东南部以及东疆最早出现日最高气温≥35℃的高温天气,进入中旬后高温范围迅速向西、向北蔓延发展,下旬初期范围达最大,南北疆均出现高温天气.新疆区域该次高温过程在7月中下旬最为强盛,全疆84.8%的测站(89站)出现高温;52.4%的测站(55站)的高温持续日数位居历史第1位;全疆21.9%的测站(23站)极端最高气温位居历史第1位,极端最高气温出现在吐鲁番东坎,达到47.7℃.这次高温过程造成8站夏季温度位居同期第1位,南疆及天山山区的7月平均气温位居历史同期第1位,有54.3%的测站(57站)7月平均气温突破同期历史极值.海拔3544 m的天山山区大西沟站7月份日最高气温连续突破历史极值,22日达到20.7℃.高温过程中,新疆区域7月0℃层高度位居1991年以来同期第1位,其中,7月19-23日连续6 d位居1991年以来的第1位.天山开都河流域日0℃层高度持续33 d高于1991-2015年平均值.7月上旬到下旬,在500 hPa高空,伊朗高压东移并控制新疆,是造成此次高温过程的直接原因.在100 hPa高空,南亚高压的形态、中心位置、强度变化与新疆此次高温过程演变关系密切.高温过程造成新疆高山区冰雪迅速消融,引发塔里木河流域出现融雪(冰)型洪水.%Meteorological datasets from 105 meteorological stations in Xinjiang were utilized to analyze the char-acteristics of extreme maximum air temperature in the summer of 2015. The extreme maximum air temperature more than 35℃firstly occurred in early July in southeastern and eastern Xinjiang region,and then spread west-wards and northwestwards in mid-July. In the late July,the range of extreme maximum air temperature reached up to the top,both in northern

  13. Extreme low temperature tolerance in woody plants

    Directory of Open Access Journals (Sweden)

    George Richard Strimbeck

    2015-10-01

    Full Text Available Woody plants in boreal to arctic environments and high mountains survive prolonged exposure to temperatures below -40˚C and minimum temperatures below -60˚C, and laboratory tests show that many of these species can also survive immersion in liquid nitrogen at -196˚C. Studies of biochemical changes that occur during acclimation, including recent proteomic and metabolomic studies, have identified changes in carbohydrate and compatible solute concentrations, membrane lipid composition, and proteins, notably dehydrins, that may have important roles in survival at extreme low temperature. Consideration of the biophysical mechanisms of membrane stress and strain lead to the following hypotheses for cellular and molecular mechanisms of survival at extreme low temperature: 1. Changes in lipid composition stabilize membranes at temperatures above the lipid phase transition temperature (-20 to 30˚C, preventing phase changes that result in irreversible injury. 2. High concentrations of oligosaccharides promote vitrification or high viscosity in the cytoplasm in freeze-dehydrated cells, which would prevent deleterious interactions between membranes. 3. Dehydrins bind membranes and further promote vitrification or act stearically to prevent membrane-membrane interactions.

  14. Summer Temperature and Spatial Variability of all-Cause Mortality in Surat City, India.

    Science.gov (United States)

    Rathi, S K; Desai, V K; Jariwala, P; Desai, H; Naik, A; Joseph, A

    2017-01-01

    Ample information is available on extreme heat associated mortality for few Indian cities, but scant literature is available on effect of temperature on spatial variability of all-cause mortality for coastal cities. To assess the effect of daily maximum temperature, relative humidity and heat index on spatial variability of all-cause mortality for summer months (March to May) from 2014 to 2015 for the urban population of Surat (coastal) city. Retrospective analysis of the all-cause mortality data with temperature and humidity was performed on a total of 9,237 deaths for 184 summer days (2014-2015). Climatic and all-cause mortality data were obtained through Tutiempo website and Surat Municipal Corporation respectively. Bivariate analysis performed through SPSS. Mean daily mortality was estimated at 50.2 ± 8.5 for the study period with a rise of 20% all-cause mortality at temperature ≥ 40°C and rise of 10% deaths per day during extreme danger level (HI: > 54°C) days. Spatial (Zone wise) analysis revealed rise of 61% all-cause mortality for Southeast and 30% for East zones at temperature ≥ 40°C. All-cause mortality increased on high summer temperature days. Presence of spatial variation in all-cause mortality provided the evidence for high risk zones. Findings may be helpful in designing the interventions at micro level.

  15. Summer temperature and spatial variability of all-cause mortality in Surat city, India

    Directory of Open Access Journals (Sweden)

    S K Rathi

    2017-01-01

    Full Text Available Background: Ample information is available on extreme heat associated mortality for few Indian cities, but scant literature is available on effect of temperature on spatial variability of all-cause mortality for coastal cities. Objective: To assess the effect of daily maximum temperature, relative humidity and heat index on spatial variability of all-cause mortality for summer months (March to May from 2014 to 2015 for the urban population of Surat (coastal city. Materials and Methods: Retrospective analysis of the all-cause mortality data with temperature and humidity was performed on a total of 9,237 deaths for 184 summer days (2014-2015. Climatic and all-cause mortality data were obtained through Tutiempo website and Surat Municipal Corporation respectively. Bivariate analysis performed through SPSS. Observations: Mean daily mortality was estimated at 50.2 ± 8.5 for the study period with a rise of 20% all-cause mortality at temperature ≥ 40°C and rise of 10% deaths per day during extreme danger level (HI: > 54°C days. Spatial (Zone wise analysis revealed rise of 61% all-cause mortality for Southeast and 30% for East zones at temperature ≥ 40°C. Conclusions: All-cause mortality increased on high summer temperature days. Presence of spatial variation in all-cause mortality provided the evidence for high risk zones. Findings may be helpful in designing the interventions at micro level.

  16. Data Converters Performance at Extreme Temperatures

    Science.gov (United States)

    Rejeshuni, Rarnesham; Kumar, Nikil; Mao, James; Keymeulen, Didier; Zebulum, Ricardo S.; Stoica, Adrian

    2006-01-01

    Space missions often require radiation and extreme-temperature hardened electronics to survive the harsh environments beyond earth's atmosphere. Traditional approaches to preserve electronics incorporate shielding, insulation and redundancy at the expense of power and weight. However, a novel way of bypassing these problems is the concept of evolutionary hardware. A reconfgurable device, consisting of several switches interconnected with analog/digital parts, is controlled by an evolutionary processor (EP). When the EP detects degradation in the circuit it sends signals to reconfgure the switches, thus forming a new circuit with the desired output. This concept has been developed since the mid-90s, but one problem remains - the EP cannot degrade substantially. For this reason, extensive testing at extreme temperatures (-180' to 120(deg)C) has been done on devices found on FPGA boards (taking the role of the EP) such as the Analog to Digital and the Digital to Analog Converter. Analysis of the results has shown that FPGA boards implementing EP with some compensation may be a practical solution to evolving circuits. This paper describes results on the tests of data converters at extreme temperatures.

  17. Processes of India's offshore summer intraseasonal sea surface temperature variability

    Digital Repository Service at National Institute of Oceanography (India)

    Kurian, N.; Lengaigne, M.; Gopalakrishna, V.V.; Vialard, J.; Pous, S.; Peter, A-C.; Durand; Naik, Shweta

    ., vol.63; 2013; 329-346 Processes of India’s offshore summer intraseasonal sea surface temperature variability K. Nisha1, M. Lengaigne1,2, V.V. Gopalakrishna,1 J. Vialard2, S. Pous2, A.-C. Peter2, F. Durand3, S.Naik1 1. NIO, CSIR, Goa, India 2...

  18. Analysis of extreme summers and prior late winter/spring conditions in central Europe

    Directory of Open Access Journals (Sweden)

    C. Träger-Chatterjee

    2013-05-01

    Full Text Available Drought and heat waves during summer in mid-latitudes are a serious threat to human health and agriculture and have negative impacts on the infrastructure, such as problems in energy supply. The appearance of such extreme events is expected to increase with the progress of global warming. A better understanding of the development of extremely hot and dry summers and the identification of possible precursors could help improve existing seasonal forecasts in this regard, and could possibly lead to the development of early warning methods. The development of extremely hot and dry summer seasons in central Europe is attributed to a combined effect of the dominance of anticyclonic weather regimes and soil moisture–atmosphere interactions. The atmospheric circulation largely determines the amount of solar irradiation and the amount of precipitation in an area. These two variables are themselves major factors controlling the soil moisture. Thus, solar irradiation and precipitation are used as proxies to analyse extreme sunny and dry late winter/spring and summer seasons for the period 1958–2011 in Germany and adjacent areas. For this purpose, solar irradiation data from the European Center for Medium Range Weather Forecast 40-yr and interim re-analysis dataset, as well as remote sensing data are used. Precipitation data are taken from the Global Precipitation Climatology Project. To analyse the atmospheric circulation geopotential data at 850 hPa are also taken from the European Center for Medium Range Weather Forecast 40-yr and interim re-analysis datasets. For the years in which extreme summers in terms of high solar irradiation and low precipitation are identified, the previous late winter/spring conditions of solar irradiation and precipitation in Germany and adjacent areas are analysed. Results show that if the El Niño–Southern Oscillation (ENSO is not very intensely developed, extremely high solar irradiation amounts, together with

  19. Analysis of extreme summers and prior late winter/spring conditions in central Europe

    Science.gov (United States)

    Träger-Chatterjee, C.; Müller, R. W.; Bendix, J.

    2013-05-01

    Drought and heat waves during summer in mid-latitudes are a serious threat to human health and agriculture and have negative impacts on the infrastructure, such as problems in energy supply. The appearance of such extreme events is expected to increase with the progress of global warming. A better understanding of the development of extremely hot and dry summers and the identification of possible precursors could help improve existing seasonal forecasts in this regard, and could possibly lead to the development of early warning methods. The development of extremely hot and dry summer seasons in central Europe is attributed to a combined effect of the dominance of anticyclonic weather regimes and soil moisture-atmosphere interactions. The atmospheric circulation largely determines the amount of solar irradiation and the amount of precipitation in an area. These two variables are themselves major factors controlling the soil moisture. Thus, solar irradiation and precipitation are used as proxies to analyse extreme sunny and dry late winter/spring and summer seasons for the period 1958-2011 in Germany and adjacent areas. For this purpose, solar irradiation data from the European Center for Medium Range Weather Forecast 40-yr and interim re-analysis dataset, as well as remote sensing data are used. Precipitation data are taken from the Global Precipitation Climatology Project. To analyse the atmospheric circulation geopotential data at 850 hPa are also taken from the European Center for Medium Range Weather Forecast 40-yr and interim re-analysis datasets. For the years in which extreme summers in terms of high solar irradiation and low precipitation are identified, the previous late winter/spring conditions of solar irradiation and precipitation in Germany and adjacent areas are analysed. Results show that if the El Niño-Southern Oscillation (ENSO) is not very intensely developed, extremely high solar irradiation amounts, together with extremely low precipitation

  20. Qualification of Fiber Optic Cables for Martian Extreme Temperature Environments

    Science.gov (United States)

    Ramesham, Rajeshuni; Lindensmith, Christian A.; Roberts, William T.; Rainen, Richard A.

    2011-01-01

    Means have been developed for enabling fiber optic cables of the Laser Induced Breakdown Spectrometer instrument to survive ground operations plus the nominal 670 Martian conditions that include Martian summer and winter seasons. The purpose of this development was to validate the use of the rover external fiber optic cabling of ChemCam for space applications under the extreme thermal environments to be encountered during the Mars Science Laboratory (MSL) mission. Flight-representative fiber optic cables were subjected to extreme temperature thermal cycling of the same diurnal depth (or delta T) as expected in flight, but for three times the expected number of in-flight thermal cycles. The survivability of fiber optic cables was tested for 600 cumulative thermal cycles from -130 to +15 C to cover the winter season, and another 1,410 cumulative cycles from -105 to +40 C to cover the summer season. This test satisfies the required 3 times the design margin that is a total of 2,010 thermal cycles (670 x 3). This development test included functional optical transmission tests during the course of the test. Transmission of the fiber optic cables was performed prior to and after 1,288 thermal cycles and 2,010 thermal cycles. No significant changes in transmission were observed on either of the two representative fiber cables subject through the 3X MSL mission life that is 2,010 thermal cycles.

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

    Science.gov (United States)

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

    2016-08-01

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

  2. Simplified hourly method to calculate summer temperatures in dwellings

    DEFF Research Database (Denmark)

    Mortensen, Lone Hedegaard; Aggerholm, Søren

    2012-01-01

    The objective of this study was to develop a method for hourly calculation of the operating temperature in order to evaluate summer comfort in dwellings to help improve building design. A simplified method was developed on the basis of the simple hourly method of the standard ISO 13790...... program for thermal simulations of buildings. The results are based on one year simulations of two cases. The cases were based on a low energy dwelling of 196 m². The transmission loss for the building envelope was 3.3 W/m², not including windows and doors. The dwelling was tested in two cases, a case...... for the fulfilment of summer comfort. Thus it is very important to address both opening areas and ventilation rates. The developed simplified method makes it possible to test whether or not a building design for a dwelling will prevent excess of the summer comfort limits set by the building regulations....

  3. Changes of reanalysis-derived Northern Hemisphere summer warm extreme indices during 1948-2006 and links with climate variability

    Science.gov (United States)

    Fang, Xingqin; Wang, Anyu; Fong, Soi-kun; Lin, Wenshi; Liu, Ji

    2008-08-01

    Using1948-2006 surface 2 m daily temperature, daily maximum temperature and daily minimum temperature of National Centers for Environmental Prediction (NCEP) reanalysis dataset, summer warm extreme indices, warm days (TG90P), warm-spell days (WSFI), warm day-times (TX90P) and warm nights (TN90P) are calculated for Gaussian grids, a complete Northern Hemisphere (NH) picture of changes of summer warm extremes is presented, and their links with El Niño/La Niña & Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO) and North Atlantic Oscillation (NAO) are also examined in this paper. The results on the NH summer seasonal basis are as follows. Warm days, warm-spell days, warm day-times and warm nights increase at rates of 2.18, 1.23, 2.31 and 2.00 days/decade respectively during 1948-2006. A broader area is exposed to frequent occurrence of warm extremes in the recent 30 years than in the last 30 years. The 59-year long-term upward trend is characterized by a positive trend reversion in the late 1970s, with a slight downward trend in the last 30 years and a rapid upward trend in the recent 30 years, representing the main form of interdecadal variance of NH warm extremes. Warm days, warm-spell days, warm day-times and warm nights increase at rates of 4.53, 3.36, 4.44 and 4.21 days/decade respectively during 1977-2006. During 1948-2006, the largest increasing rate is at central tropical Atlantic and the largest decreasing rate in Mongolia and north China. Significant (level of 0.05) upward trends cover about half of the NH during 1948-2006 and about a third of the NH during 1977-2006 with the very significant upward trends more focused, while very sparse regions have significant downward trends during these two periods. In the recent 30 years, although NH-land summer warms at a faster rate than NH-water, warm extremes on NH-water increase much faster than those on NH-land, the average warm extreme indices and their increasing trends on NH are most modulated by

  4. Simulation of extreme temperature over Odisha during May 2015

    Directory of Open Access Journals (Sweden)

    K.C. Gouda

    2017-09-01

    Full Text Available An extreme temperature event (heat wave over the state of Odisha was unique as it lasted for about 2 weeks in the 3rd and 4th weeks of May 2015. There was a similar severe heat wave in western and central Odisha in the month of April 1998. The interesting feature of the recent episodic heat wave is that it prevailed in the late pre-monsoon season with wider spread in the state of Odisha. Around 12–15 cities experienced a daily maximum temperature of over 45 °C during the strong heat wave period, and 25th −27th May was declared as the red box zone. In this study, we first analysed the intense summer temperature of 2015 May using India Meteorological Department observations of daily maximum temperature. The observed heat wave phenomenon was then simulated using the Weather Research and Forecast Model (WRFV3 at 2-km horizontal resolution to assess its ability to forecast such a rare event. The observational analysis clearly indicated that this episodic event was unique both in terms of intensity, geographical spread and duration. An optimized configuration of the WRF model is proposed and implemented for the simulation of the episodic heat wave phenomenon (daily maximum temperature over the state of Odisha. The time-ensemble simulation of the temperature is shown to be in close agreement with the station-scale observations.

  5. Spatiotemporal variability of extreme temperature frequency and amplitude in China

    Science.gov (United States)

    Zhang, Yuanjie; Gao, Zhiqiu; Pan, Zaitao; Li, Dan; Huang, Xinhui

    2017-03-01

    Temperature extremes in China are examined based on daily maximum and minimum temperatures from station observations and multiple global climate models. The magnitude and frequency of extremes are expressed in terms of return values and periods, respectively, estimated by the fitted Generalized Extreme Value (GEV) distribution of annual extreme temperatures. The observations suggest that changes in temperature extremes considerably exceed changes in the respective climatological means during the past five decades, with greater amplitude of increases in cold extremes than in warm extremes. The frequency of warm (cold) extremes increases (decreases) over most areas, with an increasingly faster rate as the extremity level rises. Changes in warm extremes are more dependent on the varying shape of GEV distribution than the location shift, whereas changes in cold extremes are more closely associated with the location shift. The models simulate the overall pattern of temperature extremes during 1961-1981 reasonably well in China, but they show a smaller asymmetry between changes in warm and cold extremes primarily due to their underestimation of increases in cold extremes especially over southern China. Projections from a high emission scenario show the multi-model median change in warm and cold extremes by 2040 relative to 1971 will be 2.6 °C and 2.8 °C, respectively, with the strongest changes in cold extremes shifting southward. By 2040, warm extremes at the 1971 20-year return values would occur about every three years, while the 1971 cold extremes would occur once in > 500 years.

  6. The paleoclimate context and future trajectory of extreme summer hydroclimate in eastern Australia

    Science.gov (United States)

    Cook, Benjamin I.; Palmer, Jonathan G.; Cook, Edward R.; Turney, Chris S. M.; Allen, Kathryn; Fenwick, Pavla; O'Donnell, Alison; Lough, Janice M.; Grierson, Pauline F.; Ho, Michelle; Baker, Patrick J.

    2016-11-01

    Eastern Australia recently experienced an intense drought (Millennium Drought, 2003-2009) and record-breaking rainfall and flooding (austral summer 2010-2011). There is some limited evidence for a climate change contribution to these events, but such analyses are hampered by the paucity of information on long-term natural variability. Analyzing a new reconstruction of summer (December-January-February) Palmer Drought Severity Index (the Australia-New Zealand Drought Atlas; ANZDA, 1500-2012 Common Era), we find moisture deficits during the Millennium Drought fall within the range of the last 500 years of natural hydroclimate variability. This variability includes periods of multidecadal drought in the 1500s more persistent than any event in the historical record. However, the severity of the Millennium Drought, which was caused by autumn (March-April-May) precipitation declines, may be underestimated in the ANZDA because the reconstruction is biased toward summer and antecedent spring (September-October-November) precipitation. The pluvial in 2011, however, which was characterized by extreme summer rainfall faithfully captured by the ANZDA, is likely the wettest year in the reconstruction for Coastal Queensland. Climate projections (Representative Concentration Pathways (RCP) 8.5 scenario) suggest that eastern Australia will experience long-term drying during the 21st century. While the contribution of anthropogenic forcing to recent extremes remains an open question, these projections indicate an amplified risk of multiyear drought anomalies matching or exceeding the intensity of the Millennium Drought.

  7. Climate change and the impact of extreme temperatures on aviation

    Science.gov (United States)

    Coffel, E.; Horton, R.

    2014-12-01

    Weather is the most significant factor affecting aircraft operations, accounting for 70-80% of passenger delays and costing airlines hundreds of millions of dollars per year in lost revenue. Temperature and airport elevation significantly influence the maximum allowable takeoff weight of an aircraft by changing the surface air density and thus the lift produced at a given speed. For a given runway length, airport elevation, and aircraft type there is a temperature threshold above which the airplane cannot take off at its maximum weight and thus must be weight restricted. The number of summer days necessitating weight restriction has increased since 1980 along with the observed increase in surface temperature. Climate change is projected to increase mean temperatures at all airports and significantly increase the frequency and severity of extreme heat events at some. These changes will negatively affect aircraft performance, leading to increased weight restrictions especially at airports with short runways and little room to expand. For a Boeing 737-800 aircraft, we find that the number of weight restriction days between May and September will increase by 50-100% at four major airports in the United States by 2050-2070 under the RCP8.5 high emissions scenario. These performance reductions may have a significant economic effect on the airline industry, leading to lower profits and higher passenger fares. Increased weight restrictions have previously been identified as potential impacts of climate change, but this study is the first to quantify the effect of higher temperatures on commercial aviation.

  8. Advanced Flip Chips in Extreme Temperature Environments

    Science.gov (United States)

    Ramesham, Rajeshuni

    2010-01-01

    The use of underfill materials is necessary with flip-chip interconnect technology to redistribute stresses due to mismatching coefficients of thermal expansion (CTEs) between dissimilar materials in the overall assembly. Underfills are formulated using organic polymers and possibly inorganic filler materials. There are a few ways to apply the underfills with flip-chip technology. Traditional capillary-flow underfill materials now possess high flow speed and reduced time to cure, but they still require additional processing steps beyond the typical surface-mount technology (SMT) assembly process. Studies were conducted using underfills in a temperature range of -190 to 85 C, which resulted in an increase of reliability by one to two orders of magnitude. Thermal shock of the flip-chip test articles was designed to induce failures at the interconnect sites (-40 to 100 C). The study on the reliability of flip chips using underfills in the extreme temperature region is of significant value for space applications. This technology is considered as an enabling technology for future space missions. Flip-chip interconnect technology is an advanced electrical interconnection approach where the silicon die or chip is electrically connected, face down, to the substrate by reflowing solder bumps on area-array metallized terminals on the die to matching footprints of solder-wettable pads on the chosen substrate. This advanced flip-chip interconnect technology will significantly improve the performance of high-speed systems, productivity enhancement over manual wire bonding, self-alignment during die joining, low lead inductances, and reduced need for attachment of precious metals. The use of commercially developed no-flow fluxing underfills provides a means of reducing the processing steps employed in the traditional capillary flow methods to enhance SMT compatibility. Reliability of flip chips may be significantly increased by matching/tailoring the CTEs of the substrate

  9. Future Projection of Summer Extreme Precipitation from High Resolution Multi-RCMs over East Asia

    Science.gov (United States)

    Kim, Gayoung; Park, Changyong; Cha, Dong-Hyun; Lee, Dong-Kyou; Suh, Myoung-Seok; Ahn, Joong-Bae; Min, Seung-Ki; Hong, Song-You; Kang, Hyun-Suk

    2017-04-01

    Recently, the frequency and intensity of natural hazards have been increasing due to human-induced climate change. Because most damages of natural hazards over East Asia have been related to extreme precipitation events, it is important to estimate future change in extreme precipitation characteristics caused by climate change. We investigate future changes in extremal values of summer precipitation simulated by five regional climate models participating in the CORDEX-East Asia project (i.e., HadGEM3-RA, RegCM4, MM5, WRF, and GRIMs) over East Asia. 100-year return value calculated from the generalized extreme value (GEV) parameters is analysed as an indicator of extreme intensity. In the future climate, the mean values as well as the extreme values of daily precipitation tend to increase over land region. The increase of 100-year return value can be significantly associated with the changes in the location (intensity) and scale (variability) GEV parameters for extreme precipitation. It is expected that the results of this study can be used as fruitful references when making the policy of disaster management. Acknowledgements The research was supported by the Ministry of Public Safety and Security of Korean government and Development program under grant MPSS-NH-2013-63 and the National Research Foundation of Korea Grant funded by the Ministry of Science, ICT and Future Planning of Korea (NRF-2016M3C4A7952637) for its support and assistant in completion of the study.

  10. Changes of Frequency of Summer Precipitation Extremes over the Yangtze River in Association with Large-scale Oceanic-atmospheric Conditions

    Institute of Scientific and Technical Information of China (English)

    WANG Yi; YAN Zhongwei

    2011-01-01

    Changes of the frequency of precipitation extremes (the number of days with daily precipitation exceeding the 90th percentile of a daily climatology,referred to as R90N) in summer (June-August) over the mid-lower reaches of the Yangtze River arc analyzed based on daily observations during 1961-2007.The first singular value decomposition (SVD) mode of R90N is linked to an ENSO-like mode of the sea surface temperature anomalies (SSTA) in the previous winter.Responses of different grades of precipitation events to the climatic mode are compared.It is notable that the frequency of summer precipitation extremes is significantly related with the SSTA in the Pacific,while those of light and moderate precipitation are not.It is suggested that the previously well-recognized impact of ENSO on summer rainfall along the Yangtze River is essentially due to a response in summer precipitation extremes in the region,in association with the East Asia-Pacific (EAP) teleconnection pattern.A negative relationship is found between the East Asian Summer Monsoon (EASM) and precipitation extremes over the mid-lower reaches of the Yangtze River.In contrast,light rainfall processes are independent from the SST and EASM variations.

  11. Long-term summer temperature variations in the Pyrenees

    Energy Technology Data Exchange (ETDEWEB)

    Buentgen, Ulf; Frank, David; Esper, Jan [Swiss Federal Research Institute WSL, Dendro Sciences Unit, Birmensdorf (Switzerland); Grudd, Haakan [Stockholm University, Department of Physical Geography and Quaternary Geology, Stockholm (Sweden)

    2008-11-15

    Two hundred and sixty one newly measured tree-ring width and density series from living and dry-dead conifers from two timberline sites in the Spanish Pyrenees were compiled. Application of the regional curve standardization method for tree-ring detrending allowed the preservation of inter-annual to multi-centennial scale variability. The new density record correlates at 0.53 (0.68 in the higher frequency domain) with May-September maximum temperatures over the 1944-2005 period. Reconstructed warmth in the fourteenth to fifteenth and twentieth century is separated by a prolonged cooling from {proportional_to}1450 to 1850. Six of the ten warmest decades fall into the twentieth century, whereas the remaining four are reconstructed for the 1360-1440 interval. Comparison with novel density-based summer temperature reconstructions from the Swiss Alps and northern Sweden indicates decadal to longer-term similarity between the Pyrenees and Alps, but disagreement with northern Sweden. Spatial field correlations with instrumental data support the regional differentiation of the proxy records. While twentieth century warmth is evident in the Alps and Pyrenees, recent temperatures in Scandinavia are relatively cold in comparison to earlier warmth centered around medieval times, {proportional_to}1450, and the late eighteenth century. While coldest summers in the Alps and Pyrenees were in-phase with the Maunder and Dalton solar minima, lowest temperatures in Scandinavia occurred later at the onset of the twentieth century. However, fairly cold summers at the end of the fifteenth century, between {proportional_to}1600-1700, and {proportional_to}1820 were synchronized over Europe, and larger areas of the Northern Hemisphere. (orig.)

  12. Recent changes in Georgia׳s temperature means and extremes: Annual and seasonal trends between 1961 and 2010

    Directory of Open Access Journals (Sweden)

    I. Keggenhoff

    2015-06-01

    Full Text Available Sixteen temperature minimum and maximum series are used to quantify annual and seasonal changes in temperature means and extremes over Georgia (Southern Caucasus during the period 1961 and 2010. Along with trends in mean minimum and maximum temperature, eight indices are selected from the list of climate extreme indices as defined by the Expert Team on Climate Change Detection and Indices (ETCCDI of the Commission for Climatology of the World Meteorological Organization (WMO, for studying trends in temperature extremes. Between the analysis periods 1961–2010, 1971–2010 and 1981–2010 pronounced warming trends are determined for all Georgia-averaged trends in temperature means and extremes, while all magnitudes of trends increase towards the most recent period. During 1981 and 2010, significant warming trends for annual minimum and maximum temperature at a rate of 0.39 °C (0.47 °C days/decade and particularly for the warm temperature extremes, summer days, warm days and nights and the warm spell duration index are evident, whereas warm extremes show larger trends than cold extremes. The most pronounced trends are determined for summer days 6.2 days/decade, while the warm spell duration index indicates an increase in the occurrence of warm spells by 5.4 days/decade during 1981 and 2010. In the comparison of seasonal changes in temperature means and extremes, the largest magnitudes of warming trends can be observed for temperature maximum in summer and temperature minimum in fall. Between 1981 and 2010, summer maximum temperature shows a significant warming at a rate of 0.84 °C/decade, increasing almost twice as fast as its annual trend (0.47 °C/decade. The Georgia-averaged trends for temperature minimum in fall increase by 0.59 °C/decade. Strongest significant trends in temperature extremes are identified during 1981 and 2010 for warm nights (4.6 days/decade in summer and fall as well as for warm days (5.6 days/decade in summer

  13. Possible Impact of the Summer North Atlantic Oscillation on Extreme Hot Events in China

    Institute of Scientific and Technical Information of China (English)

    SUN Jian-Qi

    2012-01-01

    This paper reveals that the summer North Atlantic Oscillation (SNAO) is closely related to the extreme hot event (EHE) variability in China during the period of 1979 2009, with a positive-phase (negative-phase) SNAO corresponding to less (more) EHEs in northern China. The summer circulation anomalies associated with the SNAO give further confirmation of the above relationship. In a positive-phase (negative-phase) SNAO year, there is an anomalous cyclone (anticyclone) over central East Asia, which can increase (decrease) the total cloud cover over this region. Such changes of the total cloud cover can then decrease (increase) the solar radiation reaching the surface, which is consequently unfavorable (favorable) to the formation of EHEs over northern China.

  14. Finite Temperature Field Theory of "Extreme Black Holes"

    OpenAIRE

    Degura, Yoshitaka; Shiraishi, Kiyoshi

    2000-01-01

    We treat the model which describes "extreme black holes" moving slowly. We derive an effective lagrangian in the low energy for this model and then investigate a statistical behavior of "extreme black holes" in the finite temperature.

  15. Trends in Temperature Extremes in Association with Weather-Intraseasonal Fluctuations in Eastern China

    Institute of Scientific and Technical Information of China (English)

    QIAN Cheng; YAN Zhongwei; Zhaohua WU; FU Congbin; TU Kai

    2011-01-01

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

  16. Variations in temperature and precipitation during Indian summer monsoon simulated by RegCM3

    Science.gov (United States)

    Dash, S. K.; Mamgain, A.; Pattnayak, K. C.; Giorgi, F.

    2012-04-01

    Variations in temperature and precipitation due to global changes have large societal impact in sectors such as agriculture and health. It is therefore very important to examine their temporal and spatial variations at the regional level in order to access the impact of climate change. In India, the most important quasi-periodic system to affect the weather and climate is the Indian summer monsoon. The local changes in the temperature and precipitation can be well examined by a regional model. RegCM3 is one such model best suited for the Indian region. This model has been integrated in the ensemble mode at 55km resolution over India for the summer monsoon season during the years 1982-2009. The model simulations are compared with observed values in detail. Comparison with observations shows that RegCM3 has slightly underestimated summer monsoon precipitation over the Central and Northeast India. Nevertheless, over these regions, RegCM3 simulated rainfall is closer to the observations when compared to other regions where rainfall is highly overestimated. The model simulated mid-tropospheric temperature shows a warm bias over the Himalayan and Tibetan regions that gives leads to the low pressure in the region. Thus the position of the monsoon trough as simulated by the model lies to the north of its original position. This is similar to the usual monsoon break condition leading to less rainfall over Central India. RegCM3 simulated surface maximum temperature shows large negative bias over the country while the surface minimum temperature is close to the observation. Nevertheless, there is a strong correlation between the all India weighted average surface temperature simulated by RegCM3 and IMD observations. At the regional level, in the Central India, both rainfall and temperature show the best correlation with the respective observed values. While examining the extreme condition in Central India, it is found that RegCM3 simulated frequencies of very wet and

  17. The effect of myostatin genotype on body temperature during extreme temperature events.

    Science.gov (United States)

    Howard, J T; Kachman, S D; Nielsen, M K; Mader, T L; Spangler, M L

    2013-07-01

    Extreme heat and cold events can create deleterious physiological changes in cattle as they attempt to cope. The genetic background of animals can influence their response to these events. The objective of the current study was to determine the impact of myostatin genotype (MG) on body temperature during periods of heat and cold stress. Two groups of crossbred steers and heifers of unknown pedigree and breed fraction with varying percentages of Angus, Simmental, and Piedmontese were placed in a feedlot over 2 summers and 2 winters. Before arrival, animals were genotyped for the Piedmontese-derived myostatin mutation (C313Y) to determine their MG as either homozygous normal (0 copy; n = 84), heterozygous (1 copy; n = 96), or homozygous for inactive myostatin (2 copy; n = 59). Hourly tympanic and vaginal temperature measurements were collected for steers and heifers, respectively, for 5 d during times of anticipated heat and cold stress. Mean (±SD) ambient temperature for summer and winter stress events were 24.4 (±4.64) and -1.80 (±11.71), respectively. A trigonometric function (sine + cosine) with periods of 12 and 24 h was used to describe the diurnal cyclical pattern. Hourly body temperature was analyzed within a season, and fixed effects included MG, group, trigonometric functions nested within group, and interaction of MG with trigonometric functions nested within group; random effects were animal and residual (Model [I]). A combined analysis of season and group was also investigated with the inclusion of season as a main effect and the nesting of effects within both group and season (Model [C]). In both models, the residual was fitted using an autoregressive covariance structure. A 3-way interaction of MG, season, and trigonometric function periodicities of 24 h (P 0.05). The current study illustrated that a genotype × environment interaction exists for MG and 1-copy animals were more robust to environmental extremes in comparison with 0- or 2-copy animals.

  18. Radiative Characteristics of Aerosol During Extreme Fire Event over Siberia in Summer 2012

    Science.gov (United States)

    Zhuravleva, Tatiana B.; Kabanov, Dmitriy M.; Nasrtdinov, Ilmir M.; Russkova, Tatiana V.; Sakerin, Sergey M.; Smirnov, Alexander; Holben, Brent N.

    2017-01-01

    Microphysical and optical properties of aerosol were studied during a mega-fire event in summer 2012 over Siberia using ground-based measurements of spectral solarradiation at the AERONET site in Tomsk and satellite observations. The data were analyzed using multi-year (2003-2013) measurements of aerosol characteristics under back-ground conditions and for less intense fires, differing in burning biomass type, stage of fire, remoteness from observation site, etc. (ordinary smoke). In June-August 2012, the average aerosol optical depth (AOD, 500 nm) had been 0.95+/-0.86, about a factor of 6 larger than background values (0.16+/-0.08), and a factor of 2.5 larger than in ordinary smoke. The AOD values were extremely high on 24-28 July and reached 3-5. A comparison with satellite observations showed that ground-based measurements in the region of Tomsk not only reflect the local AOD features, but are also characteristic for the territory of Western Siberia as a whole. Single scattering albedo (SSA, 440 nm) in this period ranged from 0.91 to 0.99 with an average of approx. 0.96 in the entire wavelength range of 440-1020 nm. The increase in absorptance of aerosol particles (SSA(440 nm)=0.92) and decrease in SSA with wavelength observed in ordinary smoke agree with the data from multi-year observations in analogous situations in the boreal zone of USA and Canada. Volume aerosol size distribution in extreme and ordinary smoke had a bimodal character with significant prevalence of fine-mode particles, but in summer 2012 the mean median radius and the width of the fine-mode distribution somewhat increased. In contrast to data from multi-year observations, in summer 2012 an increase in the volume concentration and median radius of the coarse mode was observed with growing AOD.

  19. Detection of quasiresonant amplification of planetary waves and their connection to northern hemisphere summer heat extremes

    Science.gov (United States)

    Kornhuber, Kai; Coumou, Dim; Petri, Stefan; Petoukhov, Vladimir

    2014-05-01

    Several recent northern hemisphere (NH) summer heat extremes have been linked to anomalous patterns of mid-latitudinal planetary waves , e.g. the European heat wave in 2003, the Russian Heat wave and Pakistani floods in 2010 and the US heat wave in 2011(Lau and Kim 2012, Black et al 2004, Petoukhov et al 2013). The NH large-scale circulation patterns in those years were characterized by persistent longitudinal planetary-scale high-amplitude waves of relative high wavenumber (6-8). A common mechanism that could lead to the observed high-amplitude planetary waves was proposed by Petukhov et al. (Petukhov et al 2013). Under certain conditions, free synoptic waves can be 'trapped' in a midlatitudinal waveguide while their amplitudes are amplified by a quasiresonant response to thermal and orographic forcing. We have searched the available reanalysis data for the emergence of waveguides for particular planetary waves and will present preliminary results of this analysis. Using spectral analysis, we quantify the planetary wave field in terms of wavenumber, amplitude, phase and eastward phase-propagation. We will present statistics of these wave quantities for periods with and without waveguides. With those conditions explicitly implemented in code we should be able to detect and point out the periods in time the requirements for amplification were met. By doing so the connection of actual summer month heat extremes to quasiresonance events can be assessed statistically. Black E., Blackburn M., Hoskins B. and Methven J.; 2004: Factors contributing to the summer 2003 European heatwave 217-23 Lau W. K. M. and Kim K.-M.; 2012: The 2010 Pakistan Flood and Russian Heat Wave: Teleconnection of Hydrometeorological Extremes J. Hydrometeorol. 13 392-403 Online: http://journals.ametsoc.org/doi/abs/10.1175/JHM-D-11-016.1 Petoukhov V., Rahmstorf S., Petri S. and Schellnhuber H .J.;2013: Quasi-resonant amplification of atmospheric planetary waves as a mechanism for recent Northern

  20. Role of Anomalous States of Upper Tropospheric Circulation on Extremely Dry and Wet Summer Monsoon Events

    Science.gov (United States)

    Ahmad, S.; Koike, T.; Nishii, K.; Shrestha, M.

    2011-12-01

    Seasonal changes in wind pattern, monsoon, sometimes result in severe droughts and intense flooding in many parts of the world including South Asian countries like Pakistan. The livelihood of a vast population in Pakistan depends on agriculture and land use is strongly influenced by water-based ecosystems that depend on the monsoon rains. Furthermore, climate change studies undertaken so far reveal that action is essential in order to prevent long term damage to water cycle and thus of great concern to the community and stakeholders. Pakistan Summer Monsoon (PSM) is affected by both the disturbances from the tropical and the extratropical regions; however there is lack of understanding of physical mechanisms of PSM compared to other regional studies i.e. Indian Summer Monsoon (ISM) and South-East Asian Monsoon (SEAM). In our study, we applied heat and vorticity budgets, and wave train analysis to reveal the mechanisms of the extremely dry and wet PSM events associated with the anomalous upper tropospheric conditions. We found that the extremely dry (wet) PSM events were closely related with the anomalous cyclonic (anticyclonic) upper-tropospheric circulation around northwest of Pakistan, and mid-upper tropospheric cooling (warming) anomaly around Pakistan and to its north/northwest. We also found in addition to Rossby wave response due to the suppressed (enhanced) convective activities around monsoon regions, the midlatitude wave energy propagation emanating around cyclonic/anticyclonic anomaly around northwestern Atlantic, northeastern Atlantic, Europe or Mediterranean regions induced/reinforced/maintained the anomalous upper tropospheric cyclonic (anticyclonic) circulation around northwest of Pakistan during extremely dry (wet) PSM events. Therefore, devastating drought (flood) events over the PSM region resulting from weak (strong) convection anomalies are induced by both the tropical and extratropical processes.

  1. Indian Summer Monsoon Rainfall: Implications of Contrasting Trends in the Spatial Variability of Means and Extremes.

    Directory of Open Access Journals (Sweden)

    Subimal Ghosh

    Full Text Available India's agricultural output, economy, and societal well-being are strappingly dependent on the stability of summer monsoon rainfall, its variability and extremes. Spatial aggregate of intensity and frequency of extreme rainfall events over Central India are significantly increasing, while at local scale they are spatially non-uniform with increasing spatial variability. The reasons behind such increase in spatial variability of extremes are poorly understood and the trends in mean monsoon rainfall have been greatly overlooked. Here, by using multi-decadal gridded daily rainfall data over entire India, we show that the trend in spatial variability of mean monsoon rainfall is decreasing as exactly opposite to that of extremes. The spatial variability of extremes is attributed to the spatial variability of the convective rainfall component. Contrarily, the decrease in spatial variability of the mean rainfall over India poses a pertinent research question on the applicability of large scale inter-basin water transfer by river inter-linking to address the spatial variability of available water in India. We found a significant decrease in the monsoon rainfall over major water surplus river basins in India. Hydrological simulations using a Variable Infiltration Capacity (VIC model also revealed that the water yield in surplus river basins is decreasing but it is increasing in deficit basins. These findings contradict the traditional notion of dry areas becoming drier and wet areas becoming wetter in response to climate change in India. This result also calls for a re-evaluation of planning for river inter-linking to supply water from surplus to deficit river basins.

  2. Indian Summer Monsoon Rainfall: Implications of Contrasting Trends in the Spatial Variability of Means and Extremes.

    Science.gov (United States)

    Ghosh, Subimal; Vittal, H; Sharma, Tarul; Karmakar, Subhankar; Kasiviswanathan, K S; Dhanesh, Y; Sudheer, K P; Gunthe, S S

    2016-01-01

    India's agricultural output, economy, and societal well-being are strappingly dependent on the stability of summer monsoon rainfall, its variability and extremes. Spatial aggregate of intensity and frequency of extreme rainfall events over Central India are significantly increasing, while at local scale they are spatially non-uniform with increasing spatial variability. The reasons behind such increase in spatial variability of extremes are poorly understood and the trends in mean monsoon rainfall have been greatly overlooked. Here, by using multi-decadal gridded daily rainfall data over entire India, we show that the trend in spatial variability of mean monsoon rainfall is decreasing as exactly opposite to that of extremes. The spatial variability of extremes is attributed to the spatial variability of the convective rainfall component. Contrarily, the decrease in spatial variability of the mean rainfall over India poses a pertinent research question on the applicability of large scale inter-basin water transfer by river inter-linking to address the spatial variability of available water in India. We found a significant decrease in the monsoon rainfall over major water surplus river basins in India. Hydrological simulations using a Variable Infiltration Capacity (VIC) model also revealed that the water yield in surplus river basins is decreasing but it is increasing in deficit basins. These findings contradict the traditional notion of dry areas becoming drier and wet areas becoming wetter in response to climate change in India. This result also calls for a re-evaluation of planning for river inter-linking to supply water from surplus to deficit river basins.

  3. Trends in daily temperature and precipitation extremes over Georgia, 1971–2010

    Directory of Open Access Journals (Sweden)

    I. Keggenhoff

    2014-08-01

    Full Text Available Annual changes to climate extreme indices in Georgia (Southern Caucasus from 1971 to 2010 are studied using homogenized daily minimum and maximum temperature and precipitation series. Fourteen extreme temperature and 11 extreme precipitation indices are selected from the list of core climate extreme indices recommended by the World Meteorological Organization – Commission for Climatology (WMO-CCL and the research project on Climate Variability and Predictability (CLIVAR of the World Climate Research Programme (WCRP. Trends in the extreme indices are studied for 10 minimum and 11 maximum temperature and 24 precipitation series for the period 1971–2010. Between 1971 and 2010 most of the temperature extremes show significant warming trends. In 2010 there are 13.3 fewer frost days than in 1971. Within the same time frame there are 13.6 more summer days and 7.0 more tropical nights. A large number of stations show significant warming trends for monthly minimum and maximum temperature as well as for cold and warm days and nights throughout the study area, whereas warm extremes and night-time based temperature indices show greater trends than cold extremes and daytime indices. Additionally, the warm spell duration indicator indicates a significant increase in the frequency of warm spells between 1971 and 2010. Cold spells show an insignificant increase with low spatial coherence. Maximum 1-day and 5-day precipitation, the number of very heavy precipitation days, very wet and extremely wet days as well as the simple daily intensity index all show an increase in Georgia, although all trends manifest a low spatial coherence. The contribution of very heavy and extremely heavy precipitation to total precipitation increased between 1971 and 2010, whereas the number of wet days decreases.

  4. Representing Extreme Temperature Events and Resolving Their Implications for Yield

    Science.gov (United States)

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

    2014-12-01

    Although it is well recognized that extreme temperatures occurring at particular growth stages are destructive to yield, there appears substantial scope for improved empirical assessment and simulation of the relationship between temperature and yield. Several anecdotes are discussed. First, a statistical analysis of historical U.S. extreme temperatures is provided. It is demonstrated that both reanalysis and model simulations significantly differ from near-surface temperature observations in the frequency and magnitude of extremes. This finding supports empirical assessment using near-surface instrumental records and underscores present difficulties in simulating past and predicting future changes. Second, an analysis of the implications of extreme temperatures on U.S. maize yield is provided where the response is resolved regionally and according to growth stage. Sensitivity to extreme temperatures during silking is found to be uniformly high across the U.S., but the response during grain filling varies spatially, with higher sensitivity in the North. This regional and growth-stage dependent sensitivity implies the importance of representing cultivar, planting times, and development rates, and is also indicative of the potential for future changes according to the combined effects of climate and technology. Finally, interaction between extreme temperatures and agriculture is indicated by analysis showing that historical extreme temperatures in the U.S. Midwest have cooled in relation to changes in regional productivity, possibly because of greater potential for cooling through evapotranspiration. This interpretation is consistent with changes in crop physiology and management, though also noteworthy is that the moderating influence of increased evapotranspiration on extreme temperatures appears to be lost during severe drought. Together, these findings indicate that a more accurate assessment of the historical relationship between extreme temperatures and yield

  5. Observed changes in extreme wet and dry spells during the South Asian summer monsoon season

    Science.gov (United States)

    Singh, Deepti; Tsiang, Michael; Rajaratnam, Bala; Diffenbaugh, Noah S.

    2014-06-01

    The South Asian summer monsoon directly affects the lives of more than 1/6th of the world's population. There is substantial variability within the monsoon season, including fluctuations between periods of heavy rainfall (wet spells) and low rainfall (dry spells). These fluctuations can cause extreme wet and dry regional conditions that adversely impact agricultural yields, water resources, infrastructure and human systems. Through a comprehensive statistical analysis of precipitation observations (1951-2011), we show that statistically significant decreases in peak-season precipitation over the core-monsoon region have co-occurred with statistically significant increases in daily-scale precipitation variability. Further, we find statistically significant increases in the frequency of dry spells and intensity of wet spells, and statistically significant decreases in the intensity of dry spells. These changes in extreme wet and dry spell characteristics are supported by increases in convective available potential energy and low-level moisture convergence, along with changes to the large-scale circulation aloft in the atmosphere. The observed changes in wet and dry extremes during the monsoon season are relevant for managing climate-related risks, with particular relevance for water resources, agriculture, disaster preparedness and infrastructure planning.

  6. Soil temperature regime and vulnerability due to extreme soil temperatures in Croatia

    Science.gov (United States)

    Sviličić, Petra; Vučetić, Višnja; Filić, Suzana; Smolić, Ante

    2016-10-01

    Soil temperature is an important factor within the climate system. Changes of trends in soil temperature and analysis of vulnerability due to heat stress can provide useful information on climate change. In this paper, the soil temperature regime was analyzed on seasonal and annual scales at depths of 2, 5, 10, 20, 30, and 50 cm at 26 sites in Croatia. Trends of maximal, mean, and minimal soil temperatures were analyzed in the periods 1961-2010 and 1981-2010. Duration of extreme soil temperatures and vulnerability due to high or low soil temperatures in the recent standard period 1981-2010 was compared with the reference climate period 1961-1990. The results show a general warming in all seasons and depths for maximal and mean temperatures in both observed periods, while only at some locations for minimal soil temperature. Warming is more pronounced in the eastern and coastal parts of Croatia in the surface layers, especially in the spring and summer season in the second period. Significant trends of maximal, minimal, and mean soil temperature in both observed periods range from 2.3 to 6.6 °C/decade, from -1.0 to 1.3 °C/decade, and from 0.1 to 2.5 °C/decade, respectively. The highest vulnerability due to heat stress at 35 °C is noted in the upper soil layers of the coastal area in both observed periods. The mountainous and northwestern parts of Croatia at surface soil layers are the most vulnerable due to low soil temperature below 0 °C. Vulnerability due to high or low soil temperature decreases with depth.

  7. Synoptic conditions leading to extremely high temperatures in Madrid

    Directory of Open Access Journals (Sweden)

    R. García

    Full Text Available Extremely hot days (EHD in Madrid have been analysed to determine the synoptic patterns that produce EHDs during the period of 1955–1998. An EHD is defined as a day with maximum temperature higher than 36.5°C, a value which is the threshold for the intense effects on mortatility and it coincides with the 95 percentile of the series. Two different situations have been detected as being responsible for an EHD occurrence, one more dynamical, produced by southern fluxes, and another associated with a stagnation situation over Iberia of a longer duration. Both account for 92% of the total number of days, thus providing an efficient classification framework. A circulation index has been derived to characterise and forecast an EHD occurrence. This paper shows that EHD occur in Madrid during short duration events, and no long heat waves, like those recorded in other cities, are present. Additionally, no clear pattern can be detected in the EHD frequency; the occurrence is tied to changes in the summer location of the Azores high.

    Key words. Meteorology and atmospheric dynamics (Climatology; synoptic-scale meteorology; general or miscellaneous

  8. Synoptic conditions leading to extremely high temperatures in Madrid

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, R.; Prieto, L.; Hernandez, E.; Teso, T. del [Dept. Fisica de la Tierra II, Fac. CC. Fisicas, Univ. Camplutense de Madrid (Spain); Diaz, J. [Centro Universitario de Salud Publica, Univ. Autonoma de Madrid (Spain)

    2002-02-01

    Extremely hot days (EHD) in Madrid have been analysed to determine the synoptic patterns that produce EHDs during the period of 1955-1998. An EHD is defined as a day with maximum temperature higher than 36.5 C, a value which is the threshold for the intense effects on mortatility and it coincides with the 95 percentile of the series. Two different situations have been detected as being responsible for an EHD occurrence, one more dynamical, produced by southern fluxes, and another associated with a stagnation situation over Iberia of a longer duration. Both account for 92% of the total number of days, thus providing an efficient classification framework. A circulation index has been derived to characterise and forecast an EHD occurrence. This paper shows that EHD occur in Madrid during short duration events, and no long heat waves, like those recorded in other cities, are present. Additionally, no clear pattern can be detected in the EHD frequency; the occurrence is tied to changes in the summer location of the Azores high. (orig.)

  9. Reconstructing 800 years of summer temperatures in Scotland from tree rings

    Science.gov (United States)

    Rydval, Miloš; Loader, Neil J.; Gunnarson, Björn E.; Druckenbrod, Daniel L.; Linderholm, Hans W.; Moreton, Steven G.; Wood, Cheryl V.; Wilson, Rob

    2017-01-01

    This study presents a summer temperature reconstruction using Scots pine tree-ring chronologies for Scotland allowing the placement of current regional temperature changes in a longer-term context. `Living-tree' chronologies were extended using `subfossil' samples extracted from nearshore lake sediments resulting in a composite chronology >800 years in length. The North Cairngorms (NCAIRN) reconstruction was developed from a set of composite blue intensity high-pass and ring-width low-pass filtered chronologies with a range of detrending and disturbance correction procedures. Calibration against July-August mean temperature explains 56.4% of the instrumental data variance over 1866-2009 and is well verified. Spatial correlations reveal strong coherence with temperatures over the British Isles, parts of western Europe, southern Scandinavia and northern parts of the Iberian Peninsula. NCAIRN suggests that the recent summer-time warming in Scotland is likely not unique when compared to multi-decadal warm periods observed in the 1300s, 1500s, and 1730s, although trends before the mid-sixteenth century should be interpreted with some caution due to greater uncertainty. Prominent cold periods were identified from the sixteenth century until the early 1800s—agreeing with the so-called Little Ice Age observed in other tree-ring reconstructions from Europe—with the 1690s identified as the coldest decade in the record. The reconstruction shows a significant cooling response 1 year following volcanic eruptions although this result is sensitive to the datasets used to identify such events. In fact, the extreme cold (and warm) years observed in NCAIRN appear more related to internal forcing of the summer North Atlantic Oscillation.

  10. "Rotten Ice": Characterizing the Physical Properties of Arctic Sea Ice Under Conditions of Extreme Summer Melt

    Science.gov (United States)

    Light, B.; Frantz, C. M.; Junge, K.; Orellana, M. V.; Carpenter, S.; Farley, S. M.; Lieb-Lappen, R.; Courville, Z.

    2016-12-01

    The microstructural properties of sea ice are central to understanding the mechanical, thermal, electrical, and optical properties of a sea ice cover. Over the course of an annual cycle, this small scale structure routinely evolves from a network of mostly isolated brine and gas inclusions prevalent in cold ice, to a more connected, more permeable structure as the ice endures summer melt processes. In the case of extreme summer melt, sea ice can become "rotten", and it is expected that such rotten ice may become more prevalent as melt seasons lengthen. Rotten ice is approximately isothermal, largely drained of brine, and is typified by the presence of large multi-cm-scale void spaces that contribute to its high permeability and low structural integrity. These properties are expected to alter the ice cover response to dynamic forcing, ability to backscatter incident light, and its melt rate. An interdisciplinary effort to characterize the physical properties of rotten first-year ice, in concert with some of its chemical and biological properties, is being carried out both in the field and in the laboratory. Time-series samples focusing on the evolution of ice microstructure were acquired and analyzed for shore-fast first-year sea ice near Barrow, Alaska in May - July of 2015. Laboratory studies have focused on assessing the seasonal evolution of optical properties of this ice, as well as the measurement of melt rates of ice grown under carefully controlled laboratory conditions. Preliminary results from these studies illuminate some of the physical and biophysical controls on late summer ice melt.

  11. Extreme Technicolor & The Walking Critical Temperature

    DEFF Research Database (Denmark)

    Sannino, Francesco; Järvinen, Matti

    2011-01-01

    We map the phase diagram of gauge theories of fundamental interactions in the flavor- temperature plane using chiral perturbation theory to estimate the relation between the pion decaying constant and the critical temperature above which chiral symmetry is restored. We then investigate the impact...

  12. Extreme Technicolor & The Walking Critical Temperature

    DEFF Research Database (Denmark)

    Sannino, Francesco; Järvinen, Matti

    2011-01-01

    We map the phase diagram of gauge theories of fundamental interactions in the flavor- temperature plane using chiral perturbation theory to estimate the relation between the pion decaying constant and the critical temperature above which chiral symmetry is restored. We then investigate the impact...

  13. Radiative characteristics of aerosol during extreme fire event over Siberia in summer 2012

    Science.gov (United States)

    Zhuravleva, Tatiana B.; Kabanov, Dmitriy M.; Nasrtdinov, Ilmir M.; Russkova, Tatiana V.; Sakerin, Sergey M.; Smirnov, Alexander; Holben, Brent N.

    2017-01-01

    Microphysical and optical properties of aerosol were studied during a mega-fire event in summer 2012 over Siberia using ground-based measurements of spectral solar radiation at the AERONET site in Tomsk and satellite observations. The data were analysed using multi-year (2003-2013) measurements of aerosol characteristics under background conditions and for less intense fires, differing in burning biomass type, stage of fire, remoteness from observation site, etc. (ordinary smoke). In June-August 2012, the average aerosol optical depth (AOD, 500 nm) had been 0.95 ± 0.86, about a factor of 6 larger than background values (0.16 ± 0.08), and a factor of 2.5 larger than in ordinary smoke. The AOD values were extremely high on 24-28 July and reached 3-5. A comparison with satellite observations showed that ground-based measurements in the region of Tomsk not only reflect the local AOD features, but are also characteristic for the territory of Western Siberia as a whole. Single scattering albedo (SSA, 440 nm) in this period ranged from 0.91 to 0.99 with an average of ˜ 0.96 in the entire wavelength range of 440-1020 nm. The increase in absorptance of aerosol particles (SSA(440 nm) = 0.92) and decrease in SSA with wavelength observed in ordinary smoke agree with the data from multi-year observations in analogous situations in the boreal zone of USA and Canada. Volume aerosol size distribution in extreme and ordinary smoke had a bimodal character with significant prevalence of fine-mode particles, but in summer 2012 the mean median radius and the width of the fine-mode distribution somewhat increased. In contrast to data from multi-year observations, in summer 2012 an increase in the volume concentration and median radius of the coarse mode was observed with growing AOD. The calculations of the average radiative effects of smoke and background aerosol are presented. Compared to background conditions and ordinary smoke, under the extreme smoke conditions the cooling

  14. Shoot desiccation and hydraulic failure in temperate woody angiosperms during an extreme summer drought.

    Science.gov (United States)

    Nardini, Andrea; Battistuzzo, Marta; Savi, Tadeja

    2013-10-01

    Plant water status and hydraulics were measured in six woody angiosperms growing in a karstic woodland, during an extreme summer drought. Our aim was to take advantage of an unusual climatic event to identify key traits related to species-specific drought damage. The damage suffered by different species was assessed in terms of percentage of individuals showing extensive crown desiccation. Stem water potential (Ψstem ) and percent loss of hydraulic conductivity (PLC) were measured in healthy and desiccated individuals. Vulnerability to cavitation was assessed in terms of stem water potential inducing 50% PLC (Ψ50 ). Stem density (ρstem ) was also measured. Species-specific percentage of desiccated individuals was correlated to Ψ50 and ρstem . Crown desiccation was more widespread in species with less negative Ψ50 and lower ρstem . Desiccated individuals had lower Ψstem and higher PLC than healthy ones, suggesting that hydraulic failure was an important mechanism driving shoot dieback. Drought-vulnerable species showed lower safety margins (Ψstem  - Ψ50 ) than resistant ones. The Ψ50 , safety margins and ρstem values emerge as convenient traits to be used for tentative predictions of differential species-specific impact of extreme drought events on a local scale. The possibility that carbohydrate depletion was also involved in induction of desiccation symptoms is discussed. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

  15. Surface temperature pattern of the Indian Ocean before summer monsoon

    Digital Repository Service at National Institute of Oceanography (India)

    Gopinathan, C.K.; Rao, D.P.

    , suggests that the position of the warmer areas in the Bay of Bengal in May is an indicator of the subsequent summer rainfall over India. The statistical method adopted for the long range forcasting of the Indian summer monsoon gives very little...

  16. Extreme temperature packaging: challenges and opportunities

    Science.gov (United States)

    Johnson, R. Wayne

    2016-05-01

    Consumer electronics account for the majority of electronics manufactured today. Given the temperature limits of humans, consumer electronics are typically rated for operation from -40°C to +85°C. Military applications extend the range to -65°C to +125°C while underhood automotive electronics may see +150°C. With the proliferation of the Internet of Things (IoT), the goal of instrumenting (sensing, computation, transmission) to improve safety and performance in high temperature environments such as geothermal wells, nuclear reactors, combustion chambers, industrial processes, etc. requires sensors, electronics and packaging compatible with these environments. Advances in wide bandgap semiconductors (SiC and GaN) allow the fabrication of high temperature compatible sensors and electronics. Integration and packaging of these devices is required for implementation into actual applications. The basic elements of packaging are die attach, electrical interconnection and the package or housing. Consumer electronics typically use conductive adhesives or low melting point solders for die attach, wire bonds or low melting solder for electrical interconnection and epoxy for the package. These materials melt or decompose in high temperature environments. This paper examines materials and processes for high temperature packaging including liquid transient phase and sintered nanoparticle die attach, high melting point wires for wire bonding and metal and ceramic packages. The limitations of currently available solutions will also be discussed.

  17. Critical mechanisms for the formation of extreme arctic sea-ice extent in the summers of 2007 and 1996

    Science.gov (United States)

    Dong, Xiquan; Zib, Behnjamin J.; Xi, Baike; Stanfield, Ryan; Deng, Yi; Zhang, Xiangdong; Lin, Bing; Long, Charles N.

    2014-07-01

    Along with significant changes in the Arctic climate system, the largest year-to-year variation in sea-ice extent (SIE) has occurred in the Laptev, East Siberian, and Chukchi seas (defined here as the area of focus, AOF), among which the two highly contrasting extreme events were observed in the summers of 2007 and 1996 during the period 1979-2012. Although most efforts have been devoted to understanding the 2007 low, a contrasting high September SIE in 1996 might share some related but opposing forcing mechanisms. In this study, we investigate the mechanisms for the formation of these two extremes and quantitatively estimate the cloud-radiation-water vapor feedback to the sea-ice-concentration (SIC) variation utilizing satellite-observed sea-ice products and the NASA MERRA reanalysis. The low SIE in 2007 was associated with a persistent anticyclone over the Beaufort Sea coupled with low pressure over Eurasia, which induced anomalous southerly winds. Ample warm and moist air from the North Pacific was transported to the AOF and resulted in positive anomalies of cloud fraction (CF), precipitable water vapor (PWV), surface LWnet (down-up), total surface energy and temperature. In contrast, the high SIE event in 1996 was associated with a persistent low pressure over the central Arctic coupled with high pressure along the Eastern Arctic coasts, which generated anomalous northerly winds and resulted in negative anomalies of above mentioned atmospheric parameters. In addition to their immediate impacts on sea ice reduction, CF, PWV and radiation can interplay to lead to a positive feedback loop among them, which plays a critical role in reinforcing sea ice to a great low value in 2007. During the summer of 2007, the minimum SIC is 31 % below the climatic mean, while the maximum CF, LWnet and PWV can be up to 15 %, 20 Wm-2, and 4 kg m-3 above. The high anti-correlations (-0.79, -0.61, -0.61) between the SIC and CF, PWV, and LWnet indicate that CF, PWV and LW radiation

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

    Science.gov (United States)

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

    2016-06-01

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

  19. Impacts of temperature extremes on cardiovascular morbidity and mortality in the Czech Republic

    Science.gov (United States)

    Davídkovová, H.; Kyselý, J.; Plavcová, E.; Urban, A.; Kriz, B.; Kyncl, J.

    2012-04-01

    Elevated mortality associated with high ambient temperatures in summer represents one of the main impacts of weather extremes on human society. Increases in cardiovascular mortality during heat waves have been reported in many European countries; much less is known about which particular cardiovascular disorders are most affected during heat waves, and whether similar patterns are found for morbidity (hospital admissions). Relatively less understood is also cold-related mortality and morbidity in winter, when the relationships between weather and human health are more complex, less direct, and confounded by other factors such as epidemics of influenza/acute respiratory infections. The present study analyses relationships between temperature extremes and cardiovascular morbidity and mortality. We make use of the datasets on hospital admissions and daily mortality in the population of the Czech Republic (about 10.3 million) over 1994-2009. The data have been standardized to remove the effects of the long-term trend and the seasonal and weekly cycles. Periods when the morbidity/mortality data were affected by epidemics of influenza and other acute respiratory infections have been removed from the analysis. We use analogous definitions for hot and cold spells based on quantiles of daily average temperature anomalies, which allows for a comparison of the findings for summer hot spells and winter cold spells. The main aims of the study are (i) to identify deviations of mortality and morbidity from the baseline associated with hot and cold spells, (ii) to compare the hot- and cold-spell effects for individual cardiovascular diseases (e.g. ischaemic heart disease I20-I25, cerebrovascular disease I60-I69, hypertension I10, aterosclerosis I70) and to identify those diagnoses that are most closely linked to temperature extremes, (iii) to identify population groups most vulnerable to temperature extremes, and (iv) to compare the links to temperature extremes for morbidity and

  20. Using damage data to estimate the risk from summer convective precipitation extremes

    Science.gov (United States)

    Schroeer, Katharina; Tye, Mari

    2017-04-01

    model to test whether the relationship between extreme rainfall events and damages is robust enough to estimate a potential underrepresentation of high intensity rainfall events in ungauged areas. Risk-relevant factors of socio-economic vulnerability, land cover, streamflow data, and weather type information are included to improve and sharpen the analysis. Within this study, we first aim to identify which rainfall events are most damaging and which factors affect the damages - seen as a proxy for the vulnerability - related to summer convective rainfall extremes in different catchment types. Secondly, we aim to detect potentially unreported damaging rainfall events and estimate the likelihood of such cases. We anticipate this damage perspective on summertime extreme convective precipitation to be beneficial for risk assessment, uncertainty management, and decision making with respect to weather and climate extremes on the regional-to-local level.

  1. Regional Summer Temperature Decrease against Global Warming in China, Landform Effect?

    Institute of Scientific and Technical Information of China (English)

    LU Aigang; PANG Deqian; HE Yuanqing; PANG Hongxi; WANG Tianming; GE Jianping

    2007-01-01

    The data of 160 national meteorological observatory (NMO) stations with long-term monthly temperature data for China were analyzed in thisstudy to show the basin-centered summer temperature decrease against global warming in the past half century. The summer and winter isotherm structures of 1950s and 1990s worked out by interpolation show the isotherm structure variations: the isotherm structure generally moves northward in winter, but in summer it is characterized with separate high-temperature and low-temperature centers and the isotherm structure moves inward the centers with global warming, indicating that the temperature in the highland areas increases but that in the lowland areas decreases in the summer of the duration. The possible mechanism of the basin-centered temperature decrease in summer is discussed in this paper.

  2. Electronic Modeling and Design for Extreme Temperatures Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We are developing CAD tools, models and methodologies for electronics design for circuit operation in extreme environments with focus on very low temperatures...

  3. Critical Mechanisms for the Formation of Extreme Arctic Sea-Ice Extent in the Summers of 2007 and 1996

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Xiquan [Beijing Normal Univ. (China); Univ. of North Dakota, Grand Forks, ND (United States); Zib, Benjamin J. [Univ. of North Dakota, Grand Forks, ND (United States); Xi, Baike [Univ. of North Dakota, Grand Forks, ND (United States); Stanfield, Ryan [Univ. of North Dakota, Grand Forks, ND (United States); Deng, Yi [Georgia Inst. of Technology, Atlanta, GA (United States); Zhang, Xiangdong [Univ. of Alaska, Fairbanks, AK (United States); Lin, B. [NASA Langley Research Center, Hampton, VA (United States); Long, Charles N. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2013-08-29

    A warming Arctic climate is undergoing significant e 21 nvironmental change, most evidenced by the reduction of Arctic sea-ice extent during the summer. In this study, we examine two extreme anomalies of September sea-ice extent in 2007 and 1996, and investigate the impacts of cloud fraction (CF), atmospheric precipitable water vapor (PWV), downwelling longwave flux (DLF), surface air temperature (SAT), pressure and winds on the sea-ice variation in 2007 and 1996 using both satellite-derived sea-ice products and MERRA reanalysis. The area of the Laptev, East Siberian and West Chukchi seas (70-90oN, 90-180oE) has experienced the largest variation in sea-ice extent from year-to-year and defined here as the Area Of Focus (AOF). The record low September sea-ice extent in 2007 was associated with positive anomalies 30 of CF, PWV, DLF, and SAT over the AOF. Persistent anti-cyclone positioned over the Beaufort Sea coupled with low pressure over Eurasia induced easterly zonal and southerly meridional winds. In contrast, negative CF, PWV, DLF and SAT anomalies, as well as opposite wind patterns to those in 2007, characterized the 1996 high September sea-ice extent. Through this study, we hypothesize the following positive feedbacks of clouds, water vapor, radiation and atmospheric variables on the sea-ice retreat during the summer 2007. The record low sea-ice extent during the summer 2007 is initially triggered by the atmospheric circulation anomaly. The southerly winds across the Chukchi and East Siberian seas transport warm, moist air from the north Pacific, which is not only enhancing sea-ice melt across the AOF, but also increasing clouds. The positive cloud feedback results in higher SAT and more sea-ice melt. Therefore, 40 more water vapor could be evaporated from open seas and higher SAT to form more clouds, which will enhance positive cloud feedback. This enhanced positive cloud feedback will then further increase SAT and accelerate the sea-ice retreat during the

  4. Temperature extremes in Western Europe and associated atmospheric anomalies

    Science.gov (United States)

    Carvalho, V. A.; Santos, J. A.

    2009-09-01

    This worḱs focal point is the analysis of temperature extremes over Western Europe in the period 1957-2007 and their relationship to large-scale anomalies in the atmospheric circulation patterns. The study is based on temperature daily time series recorded at a set of meteorological stations covering the target area. The large-scale anomalies are analyzed using data from the National Centers for Environmental Prediction reanalysis project. Firstly, a preliminary statistical analysis was undertaken in order to identify data gaps and erroneous values and to check the homogeneity of the time series, using not only elementary statistical approaches (e.g., chronograms, box-plots, scatter-plots), but also a set of non-parametric statistical tests particularly suitable for the analysis of monthly and seasonal mean temperature time series (e.g., Wald-Wolfowitz serial correlation test, Spearman and Mann-Kendall trend tests). Secondly, based on previous results, a selection of the highest quality time series was carried out. Aiming at identifying temperature extremes, we then proceed to the isolation of months with temperature values above or below pre-selected thresholds based on the empirical distribution of each time series. In particular, thresholds are based on percentiles specifically computed for each individual temperature record (data adaptive) and not on fixed values. As a result, a calendar of extremely high and extremely low monthly mean temperatures is obtained and the large-scale atmospheric conditions during each extreme are analyzed. Several atmospheric fields are considered in this study (e.g., 2-m maximum and minimum air temperature, sea level pressure, geopotential height, zonal and meridional wind components, vorticity, relative humidity) at different isobaric levels. Results show remarkably different synoptic conditions for temperature extremes in different parts of Western Europe, highlighting the different dynamical mechanisms underlying their

  5. Trends in Mediterranean gridded temperature extremes and large-scale circulation influences

    Directory of Open Access Journals (Sweden)

    D. Efthymiadis

    2011-08-01

    Full Text Available Two recently-available daily gridded datasets are used to investigate trends in Mediterranean temperature extremes since the mid-20th century. The underlying trends are found to be generally consistent with global trends of temperature and their extremes: cold extremes decrease and warm/hot extremes increase. This consistency is better manifested in the western part of the Mediterranean where changes are most pronounced since the mid-1970s. In the eastern part, a cooling is observed, with a near reversal in the last two decades. This inter-basin discrepancy is clearer in winter, while in summer changes are more uniform and the west-east difference is restricted to the rate of increase of warm/hot extremes, which is higher in central and eastern parts of the Mediterranean over recent decades. Linear regression and correlation analysis reveals some influence of major large-scale atmospheric circulation patterns on the occurrence of these extremes – both in terms of trend and interannual variability. These relationships are not, however, able to account for the most striking features of the observations – in particular the intensification of the increasing trend in warm/hot extremes, which is most evident over the last 15–20 yr in the Central and Eastern Mediterranean.

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

    Science.gov (United States)

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

    2017-01-01

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

  7. The role of synoptic and intraseasonal anomalies in the life cycle of summer rainfall extremes over South America

    Science.gov (United States)

    Hirata, Fernando E.; Grimm, Alice M.

    2016-05-01

    The main goal of this study is to describe the role of synoptic and intraseasonal anomalies during the life cycle of summer rainfall extremes over South America. Eastward-propagating synoptic-scale midlatitude waves are the main drivers of extreme precipitation events south of the Amazon and their interaction with intraseasonal anomalies over South America is important for heavy rainfall over the South Atlantic convergence zone (SACZ) region and the La Plata basin. Madden-Julian Oscillation (MJO) convective activity in the western Pacific (phases 6 and 7) leads 31 out of 81 extremes over the SACZ region by nearly 10 days. The connection between the MJO and rainfall extremes in other regions is less robust. During El Niño seasons extremes are more frequent in the La Plata basin, with decreased importance of intraseasonal anomalies. Precipitation extremes over the La Plata basin tend to be less frequent and also shorter during La Niña summers and, consequently, less hazardous. In the SACZ and the southeastern Brazilian coast, heavy rainfall is also more frequent under El Niño conditions, while La Niña episodes also increase extreme events in the southeastern coast. Extremes over the southeastern coast during El Niños are favored by strong intraseasonal anomalies flanking the subtropical jet, while during La Niñas intraseasonal anomalies are not significant.

  8. Observed changes in seasonal heat waves and warm temperature extremes in the Romanian Carpathians

    Science.gov (United States)

    Micu, Dana; Birsan, Marius-Victor; Dumitrescu, Alexandru; Cheval, Sorin

    2015-04-01

    Extreme high temperature have a large impact on environment and human activities, especially in high elevation areas particularly sensitive to the recent climate warming. The climate of the Romanian Carpathians became warmer particularly in winter, spring and summer, exibiting a significant increasing frequency of warm extremes. The paper investigates the seasonal changes in the frequency, duration and intensity of heat waves in relation to the shifts in the daily distribution of maximum temperatures over a 50-year period of meteorological observations (1961-2010). The paper uses the heat wave definition recommended by the Expert Team on Climate Change Detection and Indices (ETCCDI) and exploits the gridded daily dataset of maximum temperature at 0.1° resolution (~10 km) developed in the framework of the CarpatClim project (www.carpatclim.eu). The seasonal changes in heat waves behavior were identified using the Mann-Kendall non-parametric trend test. The results suggest an increase in heat wave frequency and a lengthening of intervals affected by warm temperature extremes all over the study region, which are explained by the shifts in the upper (extreme) tail of the daily maximum temperature distribution in most seasons. The trends are consistent across the region and are well correlated to the positive phases of the East Atlantic Oscillation. Our results are in good agreement with the previous temperature-related studies concerning the Carpathian region. This study was realized within the framework of the project GENCLIM, financed by UEFISCDI, code PN-II 151/2014.

  9. How similar are annual and summer temperature variability in central Sweden?

    Institute of Scientific and Technical Information of China (English)

    ZHANG Peng; Deliang CHEN; Hans W. LINDERHOLM; ZHANG Qiong

    2015-01-01

    Tree-ring based temperature reconstructions have successfully inferred the past inter-annual to millennium scales summer temperature variability. A clear relationship between annual and summer temperatures can provide insights into the variability of past annual mean tem-perature from the reconstructed summer temperature. However, how similar are summer and annual temperatures is to a large extent still unknown. This study aims at investigating the relationship between annual and summer temperatures at different timescales in central Sweden during the last millennium. The temperature variability in central Sweden can represent large parts of Scandinavia which has been a key region for dendroclimatological research. The observed annual and summer temperatures during 1901e2005 were firstly decomposed into different frequency bands using ensemble empirical mode decomposition (EEMD) method, and then the scale-dependent relationship was quantified using Pearson correlation coefficients. The relationship between the observed annual and summer temperatures determined by the instrumental data was subsequently used to evaluate 7 climate models. The model with the best performance was used to infer the relationship for the last millennium. The results show that the relationship between the observed annual and summer temperatures becomes stronger as the timescale increases, except for the 4e16 years timescales at which it does not show any relationship. The summer temperature variability at short timescales (2e4 years) shows much higher variance than the annual variability, while the annual temperature variability at long timescales (>32 years) has a much higher variance than the summer one. During the last millennium, the simulated summer temperature also shows higher variance at the short timescales (2e4 years) and lower variance at the long timescales (>1024 years) than those of the annual temperature. The relationship between the two temperatures is generally close at the

  10. Return Levels of Temperature Extremes in Southern Pakistan

    Science.gov (United States)

    Zahid, Maida; Lucarini, Valerio; Blender, Richard; Caterina Bramati, Maria

    2017-04-01

    Southern Pakistan (Sindh) is one of the hottest regions in the world and is highly vulnerable to temperature extremes. In order to improve rural and urban planning, information about the recurrence of temperature extremes is required. In this work, return levels of the daily maximum temperature Tmax are estimated, as well as the daily maximum wet-bulb temperature TWmax extremes. The method used is the Peak Over Threshold (POT) and it represents a novelty among the approaches previously used for similar studies in this region. Two main datasets are analyzed: temperatures observed in nine meteorological stations in southern Pakistan from 1980 to 2013, and the ERA Interim data for the nearest corresponding locations. The analysis provides the 2, 5, 10, 25, 50 and 100-year Return Levels (RLs) of temperature extremes. The 90% quantile is found to be a suitable threshold for all stations. We find that the RLs of the observed Tmax are above 50°C in northern stations, and above 45°C in the southern stations. The RLs of the observed TWmax exceed 35°C in the region, which is considered as a limit of survivability. The RLs estimated from the ERA Interim data are lower by 3°C to 5°C than the RLs assessed for the nine meteorological stations. A simple bias correction applied to ERA Interim data improves the RLs remarkably, yet discrepancies are still present. The results have potential implications for the risk assessment of extreme temperatures in Sindh.

  11. CLIMATIC FEATURES OF SUMMER TEMPERATURE IN NORTHEAST CHINA UNDER WARMING BACKGROUND

    Institute of Scientific and Technical Information of China (English)

    LI Ji; GONG Qiang; ZHAO Lian-wei

    2005-01-01

    By using, summer temperature data in 26 stations from 1951 to 2003, the variation characteristics of summer temperature in Northeast China (NET) were analyzed based on the background of climate warming. The results showed that the warming in summer was 0.15℃/10a in Northeast China, which was higher than that on the global, Northern Hemisphere or Northeast Asia scale in the recent 50 years. The responses of NET to global warming were shown in 3 aspects mainly. Firstly, it became warm and the average temperature increased in summer;secondly,the temperature variability increased, which displayed the increase of climatic instability;thirdly, the disaster of low temperature decreased and high temperature damage increased obviously, but the disaster of low temperature still existed in some areas under global warming background, which would be worthy of notice further.

  12. Characteristics of the spatiotemporal distribution of daily extreme temperature events in China: Minimum temperature records in different climate states against the background of the most probable temperature

    Institute of Scientific and Technical Information of China (English)

    Qian Zhong-Hua; Hu Jing-Guo; Feng Guo-Lin; Cao Yong-Zhong

    2012-01-01

    Based on the skewed function,the most probable temperature is defined and the spatiotemporal distributions of the frequencies and strengths of extreme temperature events in different climate states over China are investigated,where the climate states are referred to as State Ⅰ,State Ⅱ and State Ⅲ,i.e.,the daily minimum temperature records of 1961-1990,1971-2000,and 1981-2009.The results show that in space the frequency of high temperature events in summer decreases clearly in the lower and middle reaches of the Yellow River in State Ⅰ and that low temperature events decrease in northern China in State Ⅱ.In the present state,the frequency of high temperature events increases significantly in most areas over China except the north east,while the frequency of low temperature events decreases mainly in north China and the regions between the Yangtze River and the Yellow River.The distributions of frequencies and strengths of extreme temperature events are consistent in space.The analysis of time evolution of extreme events shows that the occurrence of high temperature events become higher with the change in state,while that of low temperature events decreases.High temperature events are becoming stronger as well and deserve to be paid special attention.

  13. Lysosomal responses to heat-shock of seasonal temperature extremes in Cd-exposed mussels.

    Science.gov (United States)

    Múgica, M; Izagirre, U; Marigómez, I

    2015-07-01

    The present study was aimed at determining the effect of temperature extremes on lysosomal biomarkers in mussels exposed to a model toxic pollutant (Cd) at different seasons. For this purpose, temperature was elevated 10°C (from 12°C to 22°C in winter and from 18°C to 28°C in summer) for a period of 6h (heat-shock) in control and Cd-exposed mussels, and then returned back to initial one. Lysosomal membrane stability and lysosomal structural changes in digestive gland were investigated. In winter, heat-shock reduced the labilisation period (LP) of the lysosomal membrane, especially in Cd-exposed mussels, and provoked transient lysosomal enlargement. LP values recovered after the heat-shock cessation but lysosomal enlargement prevailed in both experimental groups. In summer, heat-shock induced remarkable reduction in LP and lysosomal enlargement (more markedly in Cd-exposed mussels), which recovered within 3 days. Besides, whilst heat-shock effects on LP were practically identical for Cd-exposed mussels in winter and summer, the effects were longer-lasting in summer than in winter for control mussels. Thus, lysosomal responsiveness after heat-shock was higher in summer than in winter but recovery was faster as well, and therefore the consequences of the heat shock seem to be more decisive in winter. In contrast, inter-season differences were attenuated in the presence of Cd. Consequently, mussels seem to be better prepared in summer than in winter to stand short periods of abrupt temperature change; this is, however, compromised when mussels are exposed to pollutants such as Cd.

  14. Towards constraining extreme temperature projections of the CMIP5 ensemble

    Science.gov (United States)

    Vogel, Martha-Marie; Orth, René; Isabelle Seneviratne, Sonia

    2016-04-01

    The frequency and intensity of heat waves is expected to change in future in response to global warming. Given the severe impacts of heat waves on ecosystems and society it is important to understand how and where they will intensify. Projections of extreme hot temperatures in the IPCC AR5 model ensemble show large uncertainties for projected changes of extreme temperatures in particular in Central Europe. In this region land-atmosphere coupling can contribute substantially to the development of heat waves. This coupling is also subject to change in future, while model projections display considerable spread. In this work we link projections of changes in extreme temperatures and of changes in land-atmosphere interactions with a particular focus on Central Europe. Uncertainties in projected extreme temperatures can be partly explained by different projected changes of the interplay between latent heat and temperature as well as soil moisture. Given the considerable uncertainty in land-atmosphere coupling representation already in the current climate, we furthermore employ observational data sets to constrain the model ensemble, and consequently the extreme temperature projections.

  15. Mangrove species' responses to winter air temperature extremes in China

    Science.gov (United States)

    Chen, Luzhen; Wang, Wenqing; Li, Qingshun Q.; Zhang, Yihui; Yang, Shengchang; Osland, Michael J.; Huang, Jinliang; Peng, Congjiao

    2017-01-01

    The global distribution and diversity of mangrove forests is greatly influenced by the frequency and intensity of winter air temperature extremes. However, our understanding of how different mangrove species respond to winter temperature extremes has been lacking because extreme freezing and chilling events are, by definition, relatively uncommon and also difficult to replicate experimentally. In this study, we investigated species-specific variation in mangrove responses to winter temperature extremes in China. In 10 sites that span a latitudinal gradient, we quantified species-specific damage and recovery following a chilling event, for mangrove species within and outside of their natural range (i.e., native and non-native species, respectively). To characterize plant stress, we measured tree defoliation and chlorophyll fluorescence approximately one month following the chilling event. To quantify recovery, we measured chlorophyll fluorescence approximately nine months after the chilling event. Our results show high variation in the geographic- and species-specific responses of mangroves to winter temperature extremes. While many species were sensitive to the chilling temperatures (e.g., Bruguiera sexangula and species in the Sonneratia and Rhizophora genera), the temperatures during this event were not cold enough to affect certain species (e.g., Kandelia obovata, Aegiceras corniculatum, Avicennia marina, and Bruguiera gymnorrhiza). As expected, non-native species were less tolerant of winter temperature extremes than native species. Interestingly, tidal inundation modulated the effects of chilling. In comparison with other temperature-controlled mangrove range limits across the world, the mangrove range limit in China is unique due to the combination of the following three factors: (1) Mangrove species diversity is comparatively high; (2) winter air temperature extremes, rather than means, are particularly intense and play an important ecological

  16. Statistical modelling of wildfire size and intensity: a step toward meteorological forecasting of summer extreme fire risk

    Science.gov (United States)

    Hernandez, C.; Keribin, C.; Drobinski, P.; Turquety, S.

    2015-12-01

    In this article we investigate the use of statistical methods for wildfire risk assessment in the Mediterranean Basin using three meteorological covariates, the 2 m temperature anomaly, the 10 m wind speed and the January-June rainfall occurrence anomaly. We focus on two remotely sensed characteristic fire variables, the burnt area (BA) and the fire radiative power (FRP), which are good proxies for fire size and intensity respectively. Using the fire data we determine an adequate parametric distribution function which fits best the logarithm of BA and FRP. We reconstruct the conditional density function of both variables with respect to the chosen meteorological covariates. These conditional density functions for the size and intensity of a single event give information on fire risk and can be used for the estimation of conditional probabilities of exceeding certain thresholds. By analysing these probabilities we find two fire risk regimes different from each other at the 90 % confidence level: a "background" summer fire risk regime and an "extreme" additional fire risk regime, which corresponds to higher probability of occurrence of larger fire size or intensity associated with specific weather conditions. Such a statistical approach may be the ground for a future fire risk alert system.

  17. Climate changes in temperature and precipitation extremes in an alpine grassland of Central Asia

    Science.gov (United States)

    Hu, Zengyun; Li, Qingxiang; Chen, Xi; Teng, Zhidong; Chen, Changchun; Yin, Gang; Zhang, Yuqing

    2016-11-01

    The natural ecosystem in Central Asia is sensitive and vulnerable to the arid and semiarid climate variations, especially the climate extreme events. However, the climate extreme events in this area are still unclear. Therefore, this study analyzed the climate variability in the temperature and precipitation extreme events in an alpine grassland (Bayanbuluk) of Central Asia based on the daily minimum temperature, daily maximum temperature, and daily precipitation from 1958 to 2012. Statistically significant ( p < 0.01) increasing trends were found in the minimum temperature, maximum temperature at annual, and seasonal time scales except the winter maximum temperature. In the seasonal changes, the winter temperature had the largest contribution to the annual warming. Further, there appeared increasing trends for the warm nights and the warm days and decreasing trends for the cool nights and the cool days at a 99 % confidence level. These trends directly resulted in an increasing trend for the growing season length (GSL) which could have positively influence on the vegetation productivity. For the precipitation, it displayed an increasing trend for the annual precipitation although it was not significant. And the summer precipitation had the same variations as the annual precipitation which indicated that the precipitation in summer made the biggest contribution to the annual precipitation than the other three seasons. The winter precipitation had a significant increasing trend (1.49 mm/10a) and a decreasing trend was found in spring. We also found that the precipitation of the very wet days mainly contributes to the annual precipitation with the trend of 4.5 mm/10a. The maximum 1-day precipitation and the heavy precipitation days only had slight increasing trend. A sharp decreasing trend was found before the early 1980s, and then becoming increase for the above three precipitation indexes. The climate experienced a warm-wet abrupt climate change in the 1980s

  18. Spatial distribution of temperature extremes changes in Poland in 21st century

    Science.gov (United States)

    Jędruszkiewicz, Joanna

    2013-04-01

    There is a general agreement that changes in the frequency or intensity of extreme weather and climate events have profound impacts on both human society and the economy. In the recent years a numerous weather events have affected human health and caused enormous economic losses. A long-lasting heat waves influence society far more than rare occurred extreme high temperature. On the other hand a winter warming and frequent exceedance of 0°C during winter will be disruptive i.e. for the wheel transport and roads condition in Poland. This work is focused on the study of the spatial diversity of minimum and maximum temperature in 21st century in Poland. Firstly the shift in distribution (PDF) and cumulative distribution (CDF) of the daily maximum temperature in summer and minimum temperature in winter between control and scenario periods was compared among different part of the country. Secondly the changes in the characteristic percentiles of the temperature extremes were analyzed. Furthermore the spatial changes in the duration and frequency of the heat waves in Poland were studied. Moreover the future prediction of changes in characteristic days as hot days (Tmax≥30°C), summer days (Tmax≥25°C), tropical nights (Tmin≥20°C), frost days (Tmin<0°C), etc. were spatially compared. The diurnal temperature range (DTR) is expected to change remarkably in 21st century depending on the area of Poland. The daily minimum and maximum 2-meter temperature date have been obtained from seven different regional climate models and corrected by quintile mapping method afterwards. The Polish station data for the control period have been gained from the Institute of Meteorology and Water Management, National Research Institute.

  19. 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...

  20. Daily extreme temperature multifractals in Catalonia (NE Spain)

    Energy Technology Data Exchange (ETDEWEB)

    Burgueño, A. [Departament d' Astronomia i Meteorologia, Universitat de Barcelona, Barcelona (Spain); Lana, X., E-mail: francisco.javier.lana@upc.edu [Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya, Barcelona (Spain); Serra, C. [Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya, Barcelona (Spain); Martínez, M.D. [Departament de Física Aplicada, Universitat Politècnica de Catalunya, Barcelona (Spain)

    2014-02-01

    The multifractal character of the daily extreme temperatures in Catalonia (NE Spain) is analyzed by means of the multifractal detrended fluctuation analysis (MF-DFA) applied to 65 thermometric records covering years 1950–2004. Although no clear spatial patterns of the multifractal spectrum parameters appear, factor scores deduced from Principal Component analysis indicate some signs of spatial gradients. Additionally, the daily extreme temperature series are classified depending on their complex time behavior, through four multifractal parameters (Hurst exponent, Hölder exponent with maximum spectrum, spectrum asymmetry and spectrum width). As a synthesis of the three last parameters, a basic measure of complexity is proposed through a normalized Complexity Index. Its regional behavior is found to be free of geographical dependences. This index represents a new step towards the description of the daily extreme temperatures complexity.

  1. Can a regional climate model reproduce observed extreme temperatures?

    Directory of Open Access Journals (Sweden)

    Peter F. Craigmile

    2013-10-01

    Full Text Available Using output from a regional Swedish climate model and observations from the Swedish synoptic observational network, we compare seasonal minimum temperatures from model output and observations using marginal extreme value modeling techniques. We make seasonal comparisons using generalized extreme value models and empirically estimate the shift in the distribution as a function of the regional climate model values, using the Doksum shift function. Spatial and temporal comparisons over south central Sweden are made by building hierarchical Bayesian generalized extreme value models for the observed minima and regional climate model output. Generally speaking the regional model is surprisingly well calibrated for minimum temperatures. We do detect a problem in the regional model to produce minimum temperatures close to 0◦C. The seasonal spatial effects are quite similar between data and regional model. The observations indicate relatively strong warming, especially in the northern region. This signal is present in the regional model, but is not as strong.

  2. Extreme temperature days and potential impacts in Southern Europe

    Directory of Open Access Journals (Sweden)

    A. Cardil

    2014-06-01

    Full Text Available Extreme temperature events have consequences for human health and mortality, forest disturbance patterns, agricultural productivity, and the economic repercussions of these consequences combined. To gain insight into whether extreme temperature events are changing in light of global climate dynamics, the annual numbers of high temperature days (those with temperatures higher than 20, 22.5 and 25 °C at 850 hPa were analyzed across Southern Europe from years 1978–2012. A significant increase in the frequency of these days was found in many areas over the time period analyzed, and patterns in the spatial distribution of these changes were identified. We discuss the potential consequences of the increases in high temperature days with regards to forest fire risk, human health, agriculture, energy demands, and some potential economic repercussions.

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

    Science.gov (United States)

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

    2016-06-01

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

  4. Projected Changes in Temperature Extremes in China Using PRECIS

    Directory of Open Access Journals (Sweden)

    Yujing Zhang

    2017-01-01

    Full Text Available Temperature extremes can cause disastrous impacts on ecological and social economic systems. China is very sensitive to climate change, as its warming rate exceeds that of the global mean level. This paper focused on the spatial and temporal changes of the temperature extremes characterized by the 95th percentile of maximum temperature (TX95, the 5th percentile of the minimum temperature (TN5, high-temperature days (HTD and low-temperature days (LTD. The daily maximum and minimum temperatures generated by PRECIS under different Representative Concentration Pathways (RCPs are used in the research. The results show that: (1 Model simulation data can reproduce the spatial distribution features of the maximum temperature (Tmax and minimum temperature (Tmin as well as that of the extreme temperature indices; (2 By the end of the 21st century (2070–2099, both the Tmax and Tmin are warmer than the baseline level (1961–1990 in China and the eight sub-regions. However, there are regional differences in the asymmetrical warming features, as the Tmin warms more than the Tmax in the northern part of China and the Tibetan Plateau, while the Tmax warms more than the Tmin in the southern part of China; (3 The frequency of the warm extremes would become more usual, as the HTD characterized by the present-day threshold would increase by 106%, 196% and 346%, under RCP2.6, RCP4.5 and RCP8.5, respectively, while the cold extremes characterized by the LTD would become less frequent by the end of the 21st century, decreasing by 75%, 90% and 98% under RCP2.6, RCP4.5 and RCP8.5, respectively. The southern and eastern parts of the Tibetan Plateau respond sensitively to changes in both the hot and cold extremes, suggesting its higher likelihood to suffer from climate warming; (4 The intensity of the warm (cold extremes would increase (decrease significantly, characterized by the changes in the TX95 (TN5 by the end of the 21st century, and the magnitude of the

  5. Application of probabilistic event attribution in the summer heat extremes in the western US to emissions traced to major industrial carbon producers

    Science.gov (United States)

    Mera, R. J.; Allen, M. R.; Mote, P.; Ekwurzel, B.; Frumhoff, P. C.; Rupp, D. E.

    2015-12-01

    Heat waves in the western US have become progressively more severe due to increasing relative humidity and nighttime temperatures, increasing the health risks of vulnerable portions of the population, including Latino farmworkers in California's Central Valley and other socioeconomically disadvantaged communities. Recent research has shown greenhouse gas emissions doubled the risk of the hottest summer days during the 2000's in the Central Valley, increasing public health risks and costs, and raising the question of which parties are responsible for paying these costs. It has been argued that these costs should not be taken up solely by the general public through taxation, but that additional parties can be considered, including multinational corporations who have extracted and marketed a large proportion of carbon-based fuels. Here, we apply probabilistic event attribution (PEA) to assess the contribution of emissions traced to the world's 90 largest major industrial carbon producers to the severity and frequency of these extreme heat events. Our research uses very large ensembles of regional climate model simulations to calculate fractional attribution of policy-relevant extreme heat variables. We compare a full forcings world with observed greenhouse gases, sea surface temperatures and sea ice extent to a counter-factual world devoid of carbon pollution from major industrial carbon producers. The results show a discernable fraction of record-setting summer temperatures in the western US during the 2000's can be attributed to emissions sourced from major carbon producers.

  6. Meteorological fields variability over the Indian seas in pre and summer monsoon months during extreme monsoon seasons

    Indian Academy of Sciences (India)

    U C Mohanty; R Bhatla; P V S Raju; O P Madan; A Sarkar

    2002-09-01

    In this study, the possible linkage between summer monsoon rainfall over India and surface meteorological fields (basic fields and heat budget components) over monsoon region (30° E-120°E, 30°S-30°N) during the pre-monsoon month of May and summer monsoon season (June to September) are examined. For this purpose, monthly surface meteorological fields anomaly are analyzed for 42 years (1958-1999) using reanalysis data of NCEP/NCAR (National Center for Environmental Prediction/National Center for Atmospheric Research). The statistical significance of the anomaly (difference) between the surplus and deficient monsoon years in the surface meteorological fields are also examined by Student's t-test at 95% confidence level. Significant negative anomalies of mean sea level pressure are observed over India, Arabian Sea and Arabian Peninsular in the pre-monsoon month of May and monsoon season. Significant positive anomalies in the zonal and meridional wind (at 2m) in the month of May are observed in the west Arabian Sea off Somali coast and for monsoon season it is in the central Arabian Sea that extends up to Somalia. Significant positive anomalies of the surface temperature and air temperature (at 2m) in the month of May are observed over north India and adjoining Pakistan and Afghanistan region. During monsoon season this region is replaced by significant negative anomalies. In the month of May, significant positive anomalies of cloud amount are observed over Somali coast, north Bay of Bengal and adjoining West Bengal and Bangladesh. During monsoon season, cloud amount shows positive anomalies over NW India and north Arabian Sea. There is overall reduction in the incoming shortwave radiation flux during surplus monsoon years. A higher magnitude of latent heat flux is also found in surplus monsoon years for the month of May as well as the monsoon season. The significant positive anomaly of latent heat flux in May, observed over southwest Arabian Sea, may be considered

  7. Evaluation of dynamically downscaled extreme temperature using a spatially-aggregated generalized extreme value (GEV) model

    Science.gov (United States)

    Wang, Jiali; Han, Yuefeng; Stein, Michael L.; Kotamarthi, Veerabhadra R.; Huang, Whitney K.

    2016-11-01

    The weather research and forecast (WRF) model downscaling skill in extreme maximum daily temperature is evaluated by using the generalized extreme value (GEV) distribution. While the GEV distribution has been used extensively in climatology and meteorology for estimating probabilities of extreme events, accurately estimating GEV parameters based on data from a single pixel can be difficult, even with fairly long data records. This work proposes a simple method assuming that the shape parameter, the most difficult of the three parameters to estimate, does not vary over a relatively large region. This approach is applied to evaluate 31-year WRF-downscaled extreme maximum temperature through comparison with North American regional reanalysis (NARR) data. Uncertainty in GEV parameter estimates and the statistical significance in the differences of estimates between WRF and NARR are accounted for by conducting a novel bootstrap procedure that makes no assumption of temporal or spatial independence within a year, which is especially important for climate data. Despite certain biases over parts of the United States, overall, WRF shows good agreement with NARR in the spatial pattern and magnitudes of GEV parameter estimates. Both WRF and NARR show a significant increase in extreme maximum temperature over the southern Great Plains and southeastern United States in January and over the western United States in July. The GEV model shows clear benefits from the regionally constant shape parameter assumption, for example, leading to estimates of the location and scale parameters of the model that show coherent spatial patterns.

  8. Tree ring inferred summer temperature variations over the last millennium in western Himalaya, India

    Energy Technology Data Exchange (ETDEWEB)

    Yadav, Ram Ratan [Birbal Sahni Institute of Palaeobotany, Lucknow (India); Braeuning, Achim [University of Erlangen-Nuremberg, Institute of Geography, Erlangen (Germany); Singh, Jayendra [University Greifswald, Ecosystem Dynamics, Institute of Botany and Landscape Ecology, Greifswald (Germany)

    2011-04-15

    We report the first millennium-long reconstruction of mean summer (May-June-July-August) temperature extending back to AD 940 derived from tree-ring width data of Himalayan pencil juniper (Juniperus polycarpos C. Koch) from the monsoon-shadow zone in the western Himalaya, India. Centennial-scale variations in the reconstruction reveal periods of protracted warmth encompassing the 11-15th centuries. A decreasing trend in mean summer temperature occurred since the 15th century with the 18-19th centuries being the coldest interval of the last millennium, coinciding with the expansion of glaciers in the western Himalaya. Since the late 19th century summer temperatures increased again. However, current warming may be underestimated due to a weakening in tree growth-temperature relationship noticeable in the latter part of the 20th century. Mean summer temperature over the western Himalaya shows a positive correlation with summer monsoon intensity over north central India. Low-frequency variations in mean summer temperature anomalies over northwestern India are consistent with tree-ring inferred aridity in western North America. These far-distance linkages reported here for the first time underscore the utility of long-term temperature records from the western Himalayan region in understanding global-scale climatic patterns. (orig.)

  9. Expected changes in future temperature extremes and their elevation dependency over the Yellow River source region

    Directory of Open Access Journals (Sweden)

    Y. Hu

    2013-07-01

    Full Text Available Using the Statistical DownScaling Model (SDSM and the outputs from two global climate models, we investigate possible changes in mean and extreme temperature indices and their elevation dependency over the Yellow River source region for the two future periods 2046–2065 and 2081–2100 under the IPCC SRES A2, A1B and B1 emission scenarios. Changes in interannual variability of mean and extreme temperature indices are also analyzed. The validation results show that SDSM performs better in reproducing the maximum temperature-related indices than the minimum temperature-related indices. The projections show that by the middle and end of the 21st century all parts of the study region may experience increases in both mean and extreme temperature in all seasons, along with an increase in the frequency of hot days and warm nights and with a decrease in frost days. By the end of the 21st century, interannual variability increases in all seasons for the frequency of hot days and warm nights and in spring for frost days while it decreases for frost days in summer. Autumn demonstrates pronounced elevation-dependent changes in which around six out of eight indices show significant increasing changes with elevation.

  10. Trends in rainfall and temperature extremes in Morocco

    Directory of Open Access Journals (Sweden)

    K. Khomsi

    2015-02-01

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

  11. Smoke aerosol and its radiative effects during extreme fire event over Central Russia in summer 2010

    Directory of Open Access Journals (Sweden)

    N. Chubarova

    2012-03-01

    Full Text Available Different microphysical, optical and radiative properties of aerosol were analyzed during the severe fires in summer 2010 over Central Russia using ground measurements at two AERONET sites in Moscow (Meteorological Observatory of Moscow State University – MSU MO and Zvenigorod (Moscow Region and radiative measurements at the MSU MO. Volume aerosol size distribution in smoke conditions had a bimodal character with the significant prevalence of fine mode particles, for which effective radius was shifted to higher values (reff-fine = 0.24 μm against approximately 0.15 μm in typical conditions. For smoke aerosol, the imaginary part of refractive index (REFI in the visible spectral region was lower than that for typical aerosol (REFIλ =675 nm = 0.006 against REFIλ =675 nm = 0.01, while single scattering albedo (SSA was significantly higher (SSAλ =675 nm = 0.95 against SSAλ =675 nm ~ 0.9. Extremely high aerosol optical thickness at 500 nm (AOT500 was observed on 6–8 August reaching the absolute maximum on 7 August in Moscow (AOT500 = 6.4 and at Zvenigorod (AOT500 = 5.9. A dramatic attenuation of solar irradiance at ground was also recorded. Maximum irradiance loss had reached 64% for global shortwave irradiance, 91% for UV radiation 300–380 nm, and 97% for erythemally-weighted UV irradiance at relatively high solar elevation 47°. Significant spectral dependence in attenuation of solar irradiance in smoky conditions was mainly explained by higher AOT and smaller SSA in UV (0.8–0.9 compared with SSA in the visible region of spectrum. The assessments of radiative forcing effect (RFE at the TOA indicated a significant cooling of the smoky atmosphere. Instant RFE reached −167 Wm−2 at AOT500 = 6.4, climatological RFE calculated with August 2010 monthly mean AOT was about −65 Wm−2, compared with −20 Wm−2 for typical aerosol according to

  12. Summer temperature and drought co-variability across Europe since 850 CE

    Science.gov (United States)

    Charpentier Ljungqvist, Fredrik; Büntgen, Ulf; Cook, Edward R.; Esper, Jan; Fleitmann, Dominik; Gagen, Mary H.; García Bustamante, Elena; Fidel González-Rouco, Jesús; Krusic, Paul J.; Luterbacher, Jürg; Andrés Melo Aguilar, Camilo; Seftigen, Kristina; Seim, Andrea; Solomina, Olga; Werner, Johannes P.; Xoplaki, Elena; Zorita, Eduardo

    2017-04-01

    Under the present global warming condition the increasing risk of droughts and floods is a major concern. Droughts have severe consequences for agricultural productivity across wide areas. However, state-of-the-art climate models are not consistent in their projections of hydroclimate changes under global warming, on regional scales, which limits attempts at defining long-term mitigation strategies. A better understanding of past summer temperature and hydroclimate co-variability will provide valuable empirical information on how increasing/decreasing temperatures will affect summer drought conditions at different time-scales over Europe. We use instrumental data, the new gridded tree-ring-derived Old World Drought Atlas by Cook et al. (2015), the gridded European summer temperature reconstruction by Luterbacher et al. (2016), as well as two high-resolution last millennium (850-2005 CE) climate simulations (CCSM4 and MPI-ESM-P), to assess the spatio-temporal co-variability of summer temperature and summer drought over Europe, at inter-annual to centennial time-scales, since 850 CE. This allows us to i) investigate potential changes in the dominating patterns of co-variability at different time scales, and ii) assess the accuracy and precision of climate models to simulate summer temperature and summer drought co-variability as found in both the 20th century instrumental data and millennium-long tree-ring based climate reconstructions. The discussion of cross-spectral analyses of temperature and drought will likely improve our understanding of the long-term co-variability of these important climate variables at continental scales in Europe. References: Cook, E.R., et al. (2015) Old World megadroughts and pluvials during the Common Era. Science Advances, 1, e1500561, doi:10.1126/sciadv.1500561. Luterbacher, J., et al. (2016) European summer temperatures since Roman times. Environmental Research Letters 11, e024001, doi:10.1088/1748-9326/11/1/024001.

  13. Nerve conduction studies in upper extremities: skin temperature corrections.

    Science.gov (United States)

    Halar, E M; DeLisa, J A; Soine, T L

    1983-09-01

    The relationship of skin to near nerve (NN) temperature and to nerve conduction velocity (NCV) and distal latency (DL) was studied in 34 normal adult subjects before and after cooling both upper extremities. Median and ulnar motor and sensory NCV, DL, and NN temperature were determined at ambient temperature (mean X skin temp = 33 C) and after cooling, at approximately 26, 28, and 30 C of forearm skin temperature. Skin temperatures on the volar side of the forearm, wrist, palm, and fingers and NN temperature at the forearm, midpalm, and thenar or hypothenar eminence were compared with respective NCV and DL. Results showed a significant linear correlation between skin temperature and NN temperature at corresponding sites (r2 range, 0.4-0.84; p less than 0.005). Furthermore, both skin and NN temperatures correlated significantly with respective NCV and DL. Midline wrist skin temperature showed the best correlation to NCV and DL. Median motor and sensory NCV were altered 1.5 and 1.4m/sec/C degree and their DL 0.2 msec/C degree of wrist skin temperature change, respectively. Ulnar motor and sensory NCV were changed 2.1 and 1.6m/sec/C degree respectively, and 0.2 msec/C degree wrist temperature for motor and sensory DL. Average ambient skin temperature at the wrist (33 C) was used as a standard skin temperature in the temperature correction formula: NCV or DL(temp corrected) = CF(Tst degree - Tm degree) + obtained NCV or DL, where Tst = 33 C for wrist, Tm = the measured skin temperature, and CF = correction factor of tested nerve. Use of temperature correction formula for NCV and DL is suggested in patients with changed wrist skin temperature outside 29.6-36.4C temperature range.

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

    Science.gov (United States)

    Caloiero, Tommaso

    2017-07-01

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

  15. Lake Superior summer water temperatures are increasing more rapidly than regional air temperatures: A positive ice-albedo feedback

    Science.gov (United States)

    Austin, Jay A.; Colman, Steven M.

    2007-03-01

    Lake Superior summer (July-September) surface water temperatures have increased approximately 2.5°C over the interval 1979-2006, equivalent to a rate of (11 +/- 6) × 10-2°C yr-1, significantly in excess of regional atmospheric warming. This discrepancy is caused by declining winter ice cover, which is causing the onset of the positively stratified season to occur earlier at a rate of roughly a half day per year. An earlier start of the stratified season significantly increases the period over which the lake warms during the summer months, leading to a stronger trend in mean summer temperatures than would be expected from changes in summer air temperature alone.

  16. Significant influences of global mean temperature and ENSO on extreme rainfall over Southeast Asia

    Science.gov (United States)

    Villafuerte, Marcelino, II; Matsumoto, Jun

    2014-05-01

    Along with the increasing concerns on the consequences of global warming, and the accumulating records of disaster related to heavy rainfall events in Southeast Asia, this study investigates whether a direct link can be detected between the rising global mean temperature, as well as the El Niño-Southern Oscillation (ENSO), and extreme rainfall over the region. The maximum likelihood modeling that allows incorporating covariates on the location parameter of the generalized extreme value (GEV) distribution is employed. The GEV model is fitted to annual and seasonal rainfall extremes, which were taken from a high-resolution gauge-based gridded daily precipitation data covering a span of 57 years (1951-2007). Nonstationarities in extreme rainfall are detected over the central parts of Indochina Peninsula, eastern coasts of central Vietnam, northwest of the Sumatra Island, inland portions of Borneo Island, and on the northeastern and southwestern coasts of the Philippines. These nonstationarities in extreme rainfall are directly linked to near-surface global mean temperature and ENSO. In particular, the study reveals that a kelvin increase in global mean temperature anomaly can lead to an increase of 30% to even greater than 45% in annual maximum 1-day rainfall, which were observed pronouncedly over central Vietnam, southern coast of Myanmar, northwestern sections of Thailand, northwestern tip of Sumatra, central portions of Malaysia, and the Visayas island in central Philippines. Furthermore, a pronounced ENSO influence manifested on the seasonal maximum 1-day rainfall; a northward progression of 10%-15% drier condition over Southeast Asia as the El Niño develops from summer to winter is revealed. It is important therefore, to consider the results obtained here for water resources management as well as for adaptation planning to minimize the potential adverse impact of global warming, particularly on extreme rainfall and its associated flood risk over the region

  17. Changes in annual temperature and precipitation extremes in the Carpathians since AD 1961

    Science.gov (United States)

    Dumitrescu, Alexandru; Birsan, Marius-Victor; Magdalena Micu, Dana; Cheval, Sorin

    2014-05-01

    The Carpathians are the largest, longest, most twisted and fragmented segment of the Alpine system, stretching between latitudes 44°N and 50°N, and longitudes 17°E and 27°E. This European mountain range is a climatically transitional region between major atmospheric circulation source areas of the Atlantic Ocean, Mediterranean Sea and continental Europe. The region is a European biodiversity hotspot, containing over one third of all European plant species. It is acknowledged that the mountain regions are particularly sensitive and vulnerable to climate change than any other regions located at the same latitudes. Observational studies on the variability and trends of extreme events suggest an overall consensus towards a significant increase in the frequency, duration and intensity of warm extremes in most of these regions, including the Carpathians. 15 core indices, defined by the Expert Team on Climate Change Detection and Indices (ETCCDI), were computed in order to investigate the changes in annual temperature and precipitation extremes, based on their known relevance for the infrastructure, human health and tourism activities in these mountains. The indices were computed from gridded daily datasets of minimum and maximum temperature and precipitation at 0.1° resolution (~10 km), available online within the framework of the project CarpatClim (www.carpatclim-eu.org) for the period 1961-2010. Changes in the annual temperature and precipitation extremes in the last five decades have been identified with the Mann-Kendall non-parametric trend test, at the 90% significance level (two-tail test). The results show decreasing trends in cold-related thermal indices, especially in the number of frost days, and increasing trends in warm-related ones. No consistent trend in precipitation extremes has been found. There is a generally uniform signal of significant increasing trends in the frequency of summer days across the Carpathians, with no obvious differences between

  18. Projected changes in precipitation extremes linked to temperature over Japan

    Science.gov (United States)

    Nayak, S.; Dairaku, K.; Takayabu, I.; Suzuki-Parker, A.

    2015-12-01

    Recent studies have argued that the extreme precipitation intensities are increasing in many regions across the globe due to atmospheric warming. This argument is based on the principle of Clausius-Clapeyron relationship which states that the atmosphere can hold more moisture in warmer air temperature (~7%/°C). In our study, we have investigated the precipitation extremes linked to temperature in current climate (1981-2000) and their projected changes in late 21st century (2081-2100, RCP4.5) over Japan from multi-model ensemble downscaling experiments by three RCMs (NHRCM, NRAMS, WRF) forced by JRA25 as well as three GCMs (CCSM4, MIROC5, MRI-GCM3). To do this, the precipitation intensities of wet days (defined as ≥ 0.05 mm/d) are stratified to different bins with 1°C temperature interval. We have also identified the occurrences of precipitation extremes in different spell durations and associated peak intensities exceeding various thresholds in two climate periods. We found that extreme precipitation intensities are increased by 5 mm/d in future climate for temperatures above 21°C (Fig. 1). Precipitation extremes of higher percentiles are projected to have larger increase rates in future climate scenarios (3-5%/°C in the current climate and 4-6%/°C in the future climate scenarios). The joint probability distribution of wet hours (≥1mm/h) with various peak intensities under future climate scenarios (RCP4.5) of the late 21st century suggests an increase of long-lived (>10hr) and short-lived (1-2hr) events. On the other hand, a relatively decrease of medium-lived events (3-10hr) are noticed in future climate scenario. The increase of extreme precipitation intensities in future climate is due to the increase in temperature under RCP4.5 (~2°C). Increase in temperature causes more evapotranspiration and subsequently increases the water vapor in the atmosphere.

  19. NAO influence on extreme winter temperatures in Madrid (Spain)

    Energy Technology Data Exchange (ETDEWEB)

    Prieto, L.; Garcia, R.; Hernandez, E.; Teso, T. del [Dept. Fisica de la Tierra II, Fac. CC. Fisicas, Univ. Complutense de Madrid (Spain); Diaz, J. [Centro Universitario de Salud Publica, Univ. Autonoma de Madrid (Spain)

    2002-12-01

    Extremely cold days (ECDs), with minimum temperatures lower than -4.6 C, have been analysed for Madrid. This threshold corresponds to the 5th percentile of the period 1963-1999. Adopting a case analysis approach, five synoptic patterns have been identified that produce these extremely low temperatures. Three of them are associated with cold air flows over the Iberian Peninsula, and the other two with a lack of significant circulation over the region. A non-linear association with the North Atlantic oscillation (NAO) has been identified using log-linear models. The NAO positive phase leads to an increase in the winter frequency of those synoptic patterns associated with stagnant air flow over Iberia, while those characterised by cold, northern flows do not appear to be similarly influenced. (orig.)

  20. Poorest countries experience earlier anthropogenic emergence of daily temperature extremes

    Science.gov (United States)

    Harrington, Luke J.; Frame, David J.; Fischer, Erich M.; Hawkins, Ed; Joshi, Manoj; Jones, Chris D.

    2016-05-01

    Understanding how the emergence of the anthropogenic warming signal from the noise of internal variability translates to changes in extreme event occurrence is of crucial societal importance. By utilising simulations of cumulative carbon dioxide (CO2) emissions and temperature changes from eleven earth system models, we demonstrate that the inherently lower internal variability found at tropical latitudes results in large increases in the frequency of extreme daily temperatures (exceedances of the 99.9th percentile derived from pre-industrial climate simulations) occurring much earlier than for mid-to-high latitude regions. Most of the world’s poorest people live at low latitudes, when considering 2010 GDP-PPP per capita; conversely the wealthiest population quintile disproportionately inhabit more variable mid-latitude climates. Consequently, the fraction of the global population in the lowest socio-economic quintile is exposed to substantially more frequent daily temperature extremes after much lower increases in both mean global warming and cumulative CO2 emissions.

  1. Nonlinear response of summer temperature to Holocene insolation forcing in Alaska.

    Science.gov (United States)

    Clegg, Benjamin F; Kelly, Ryan; Clarke, Gina H; Walker, Ian R; Hu, Feng Sheng

    2011-11-29

    Regional climate responses to large-scale forcings, such as precessional changes in solar irradiation and increases in anthropogenic greenhouse gases, may be nonlinear as a result of complex interactions among earth system components. Such nonlinear behaviors constitute a major source of climate "surprises" with important socioeconomic and ecological implications. Paleorecords are key for elucidating patterns and mechanisms of nonlinear responses to radiative forcing, but their utility has been greatly limited by the paucity of quantitative temperature reconstructions. Here we present Holocene July temperature reconstructions on the basis of midge analysis of sediment cores from three Alaskan lakes. Results show that summer temperatures during 10,000-5,500 calibrated years (cal) B.P. were generally lower than modern and that peak summer temperatures around 5,000 were followed by a decreasing trend toward the present. These patterns stand in stark contrast with the trend of precessional insolation, which decreased by ∼10% from 10,000 y ago to the present. Cool summers before 5,500 cal B.P. coincided with extensive summer ice cover in the western Arctic Ocean, persistence of a positive phase of the Arctic Oscillation, predominantly La Niña-like conditions, and variation in the position of the Alaskan treeline. These results illustrate nonlinear responses of summer temperatures to Holocene insolation radiative forcing in the Alaskan sub-Arctic, possibly because of state changes in the Arctic Oscillation and El Niño-Southern Oscillation and associated land-atmosphere-ocean feedbacks.

  2. Spectrophotometry of extreme helium stars - Ultraviolet fluxes and effective temperatures

    Science.gov (United States)

    Heber, U.; Drilling, J. S.; Schoenberner, D.; Lynas-Gray, A. E.

    1984-01-01

    Ultraviolet flux distributions are presented for the extremely helium rich stars BD +10 deg 2179, HD 124448, LSS 3378, BD -9 deg 4395, LSE 78, HD 160641, LSIV -1 deg 2, BD 1 deg 3438, HD 168476, MV Sgr, LS IV-14 deg 109 (CD -35 deg 11760), LSII +33 deg 5 and BD +1 deg 4381 (LSIV +2 deg 13) obtained with the International Ultraviolet Explorer (IUE). Broadband photometry and a newly computed grid of line blanketed model atmospheres were used to determine accurate angular diameters and total stellar fluxes. The resultant effective temperatures are in most cases in satisfactory agreement with those based on broadband photometry and/or high resolution spectroscopy in the visible. For two objects, LSII +33 deg 5 and LSE 78, disagreement was found between the IUE observations and broadband photometry: the colors predict temperatures around 20,000 K, whereas the UV spectra indicate much lower photospheric temperatures of 14,000 to 15,000 K. The new temperature scale for extreme helium stars extends to lower effective temperatures than that of Heber and Schoenberner (1981) and covers the range from 8,500 K to 32,000 K. Previously announced in STAR as N83-24433

  3. Analysis on the Extreme Heat Wave over China around Yangtze River Region in the Summer of 2013 and Its Main Contributing Factors

    Directory of Open Access Journals (Sweden)

    Jin Li

    2015-01-01

    Full Text Available In the summer of 2013, a rare extreme heat wave occurred in the middle and lower reaches of the Yangtze River in China. Based on high resolution reanalysis data from ECMWF, comprehensive analyses on the associated atmospheric circulation and the sea surface temperature anomaly (SSTA were provided. The stable and strong West Pacific Subtropical High (WPSH was the direct cause for the heat wave. The WPSH had four westward extensions, which brought about four hot spells in southern China. The South Asia High (SAH at 150 hPa was more eastward and more northward than normal. The strong Hadley circulation in the central and western Pacific and the anomalous easterlies at 500 hPa and 250 hPa in the middle and high latitudes were favorable for more hot days (HDs. The total HDs in the middle and lower reaches of the Yangtze River had close relationships with the zonal wind anomalies in the middle and high latitudes, the SSTA in the Indian Ocean and Pacific, and the dry soil conditions of the Yangtze River Valley in spring and summer. The anomalies of the tropical, subtropical, and polar circulation and the underlying surfaces could be responsible for this extreme heat wave.

  4. Reanalysis Data Evaluation to Study Temperature Extremes in Siberia

    Science.gov (United States)

    Shulgina, T. M.; Gordov, E. P.

    2014-12-01

    Ongoing global climate changes are strongly pronounced in Siberia by significant warming in the 2nd half of 20th century and recent extreme events such as 2010 heat wave and 2013 flood in Russia's Far East. To improve our understanding of observed climate extremes and to provide to regional decision makers the reliable scientifically based information with high special and temporal resolution on climate state, we need to operate with accurate meteorological data in our study. However, from available 231 stations across Siberia only 130 of them present the homogeneous daily temperature time series. Sparse, station network, especially in high latitudes, force us to use simulated reanalysis data. However those might differ from observations. To obtain reliable information on temperature extreme "hot spots" in Siberia we have compared daily temperatures form ERA-40, ERA Interim, JRA-25, JRA-55, NCEP/DOE, MERRA Reanalysis, HadEX2 and GHCNDEX gridded datasets with observations from RIHMI-WDC/CDIAC dataset for overlap period 1981-2000. Data agreement was estimated at station coordinates to which reanalysis data were interpolated using modified Shepard method. Comparison of averaged over 20 year annual mean temperatures shows general agreement for Siberia excepting Baikal region, where reanalyses significantly underestimate observed temperature behavior. The annual temperatures closest to observed one were obtained from ERA-40 and ERA Interim. Furthermore, t-test results show homogeneity of these datasets, which allows one to combine them for long term time series analysis. In particular, we compared the combined data with observations for percentile-based extreme indices. In Western Siberia reanalysis and gridded data accurately reproduce observed daily max/min temperatures. For East Siberia, Lake Baikal area, ERA Interim data slightly underestimates TN90p and TX90p values. Results obtained allows regional decision-makers to get required high spatial resolution (0,25°×0

  5. A 560 yr summer temperature reconstruction for the Western Mediterranean basin based on stable carbon isotopes from Pinus nigra ssp. laricio (Corsica/France

    Directory of Open Access Journals (Sweden)

    J. Kuhlemann

    2012-10-01

    Full Text Available The Mediterranean is considered as an area which will be affected strongly by current climate change. However, temperature records for the past centuries which can contribute to a better understanding of future climate changes are still sparse for this region. Carbon isotope chronologies from tree-rings often mirror temperature history but their application as climate proxies is difficult due to the influence of the anthropogenic change in atmospheric CO2 on the carbon isotope fractionation during photosynthetic CO2 uptake. We tested the influence of different correction models accounting for plant response to increased atmospheric CO2 on four annually resolved long-term carbon isotope records (between 400 and 800 yr derived from Corsican pine trees (Pinus nigra ssp. laricio growing at ecologically varying mountain sites on the island of Corsica. The different correction factors have only a minor influence on the main climate signals and resulting temperature reconstructions. Carbon isotope series show strong correlations with summer temperature and precipitation. A summer temperature reconstruction (1448–2007 AD reveals that the Little Ice Age was characterised by low, but not extremely low temperatures on Corsica. Temperatures have been to modern temperatures at around 1500 AD. The reconstruction reveals warm summers during 1480–1520 and 1950–2007 AD and cool summers during 1580–1620 and 1820–1890 AD.

  6. Increased Stream Temperature in Response to Extreme Precipitation Events

    Science.gov (United States)

    Wilson, C. E.; Gooseff, M. N.

    2016-12-01

    Aquatic ecosystem temperature regulation is essential to the survival of riverine fish species restricted to limited water temperature ranges. Dissolved oxygen levels, similarly necessary to fish health, are decreased by rising temperatures, as warmer waters can hold less oxygen than colder waters. Climate change projections forecast increased precipitation intensities, a trend that has already been observed in the past decade. Though extreme events are becoming more common, the stream temperature response to high-intensity rainfall is not yet completely understood. Precipitation and stream temperature records from gages in the Upper Midwestern United States were analyzed to determine whether there exists a positive relationship between high-intensity rainfall and stream temperature response. This region was chosen for its already observed trends in increasing precipitation intensity, and rural gages were used in order to minimize the effect of impervious surfaces on runoff amounts and temperature. Days with recorded precipitation were divided by an intensity threshold and classified as either high-intensity or low-intensity days. While the effects of rain events on temperature are variable, increases in stream temperature in response to high-intensity rainfall were observed. For some basins, daily maximum rates of stream temperature increase were, on average, greater for higher intensity events. Similarly, the average daily stream temperature range was higher in streams on days of high-intensity precipitation, compared to days of low-intensity events. Understanding the effect of increasing precipitation intensity in conjunction with rising air temperatures will provide insight into the future of aquatic ecosystems and their adaptation to climate change.

  7. Global and Regional Variations in Mean Temperature and Warm Extremes in Large-Member Historical AGCM Simulation

    Science.gov (United States)

    Kamae, Y.; Shiogama, H.; Imada, Y.; Mori, M.; Arakawa, O.; Mizuta, R.; Yoshida, K.; Ishii, M.; Watanabe, M.; Kimoto, M.; Ueda, H.

    2015-12-01

    Frequency of heat extremes during the summer season has increased continuously since the late 20th century despite the global warming hiatus. In previous studies, anthropogenic influences, natural variation in sea surface temperature (SST), and internal atmospheric variabilities are suggested to be factors contributing to the increase in the frequency of warm extremes. Here 100-member ensemble historical simulations were performed (called "database for Probabilistic Description of Future climate"; d4PDF) to examine physical mechanisms responsible for the increasing hot summers and attribute to the anthropogenic influences or natural climate variability. 60km resolution MRI-AGCM ensemble simulations can reproduce historical variations in the mean temperature and warm extremes. Natural SST variability in the Pacific and Atlantic Oceans contribute to the decadal variation in the frequency of hot summers in the Northern Hemisphere middle latitude. For example, the surface temperature over western North America, including California, is largely influenced by anomalous atmospheric circulation pattern associated with Pacific SST variability. Future projections based on anomalous SST patterns derived from coupled climate model simulations will also be introduced.

  8. Multidecadal changes in the relationship between extreme temperature events in Uruguay and the general atmospheric circulation

    Energy Technology Data Exchange (ETDEWEB)

    Renom, Madeleine; Barreiro, Marcelo [Universidad de la Republica, Unidad de Ciencias de la Atmosfera, Instituto de Fisica, Facultad de Ciencias, Montevideo (Uruguay); Rusticucci, Matilde [Universidad de Buenos Aires, Departamento de Ciencias de la Atmosfera y los Oceanos, Facultad de Ciencias Exactas y Naturales, Buenos Aires (Argentina)

    2011-12-15

    We analyze changes in the relationship between extreme temperature events and the large scale atmospheric circulation before and after the 1976 climate shift. To do so we first constructed a set of two temperature indices that describe the occurrence of warm nights (TN90) and cold nights (TN10) based on a long daily observed minimum temperature database that spans the period 1946-2005, and then divided the period into two subperiods of 30 years each (1946-1975 and 1976-2005). We focus on summer (TN10) and winter (TN90) seasons. During austral summer before 1976 the interannual variability of cold nights was characterized by a negative phase of the Southern Annular Mode (SAM) with a cyclonic anomaly centered off Uruguay that favoured the entrance of cold air from the south. After 1976 cold nights are associated not with the SAM, but with an isolated vortex at upper levels over South Eastern South America. During austral winter before 1976, the El Nino phenomenon dominated the interannual variability of warm nights through an increase in the northerly warm flow into Uruguay. However, after 1976 the El Nino connection weakened and the variability of warm nights is dominated by a barotropic anticyclonic anomaly located in the South Atlantic and a low pressure center over South America. This configuration also strengthens the northward flow of warm air into Uruguay. Our results suggest that changes in El Nino evolution after 1976 may have played a role in altering the relationship between temperature extreme events in Uruguay and the atmospheric circulation. (orig.)

  9. Transport Coefficients at Zero Temperature from Extremal Black Holes

    CERN Document Server

    Edalati, Mohammad; Leigh, Robert G

    2009-01-01

    Using the AdS/CFT correspondence we study transport coefficients of a strongly-coupled (2 +1)-dimensional boundary field theory at zero temperature and finite charge density. The boundary field theory under consideration is dual to the extremal Reissner-Nordstrom AdS(4) black hole in the bulk. We show that, like the cases of scalar and spinor operators studied in arXiv:0907.2694 [hep-th], the correlators of charge (vector) current and energy-momentum (tensor) operators exhibit scaling behavior at low frequency. The existence of such low frequency behavior is related to the fact that the near-horizon geometry of the extremal black hole background has an AdS(2) factor. We carefully calculate the shear viscosity (at zero temperature) and show that the ratio of the shear viscosity to the entropy density takes the value of 1/4\\pi. Because of the AdS(2) factor, we argue that this result stays the same for all d-dimensional boundary field theories dual to the extremal Reissner-Nordstrom AdS(d+1) black holes. Also, w...

  10. Synthesis and microdiffraction at extreme pressures and temperatures.

    Science.gov (United States)

    Lavina, Barbara; Dera, Przemyslaw; Meng, Yue

    2013-10-07

    High pressure compounds and polymorphs are investigated for a broad range of purposes such as determine structures and processes of deep planetary interiors, design materials with novel properties, understand the mechanical behavior of materials exposed to very high stresses as in explosions or impacts. Synthesis and structural analysis of materials at extreme conditions of pressure and temperature entails remarkable technical challenges. In the laser heated diamond anvil cell (LH-DAC), very high pressure is generated between the tips of two opposing diamond anvils forced against each other; focused infrared laser beams, shined through the diamonds, allow to reach very high temperatures on samples absorbing the laser radiation. When the LH-DAC is installed in a synchrotron beamline that provides extremely brilliant x-ray radiation, the structure of materials under extreme conditions can be probed in situ. LH-DAC samples, although very small, can show highly variable grain size, phase and chemical composition. In order to obtain the high resolution structural analysis and the most comprehensive characterization of a sample, we collect diffraction data in 2D grids and combine powder, single crystal and multigrain diffraction techniques. Representative results obtained in the synthesis of a new iron oxide, Fe4O5 (1) will be shown.

  11. Risky Adaptation: The Effect of Temperature Extremes on HIV Prevalence

    Science.gov (United States)

    Baker, R.

    2016-12-01

    Previous work has linked rainfall shock to an increase in HIV prevalence in Sub-Saharan Africa. In this paper we take advantage of repeated waves of the Demographic and Health Survey (DHS) and a new high resolution climate dataset for the African continent to test the non-linear relationship between temperature and HIV. We find a strong and significant relationship between recent high temperatures and increases in HIV prevalence in a region. We then test the effect of temperature on risk factors that may contribute to this increase. High temperatures are linked to an increase in sexual violence, number of partners and a decrease in condom usage - all of which may contribute to the uptake in HIV rate. This paper contributes to the literature on adaptation from two standpoints. First, we suggest that some behavioral changes that are classed as adaptations, in the sense that they allow for consumption smoothing in the face of extreme temperatures, may carry unexpected risks to the individuals involved. Second, we find preliminary evidence that the relationship between temperature and these risky behaviors is diminished in regions prone to higher temperatures, suggesting some adaptation is possible in the long run.

  12. Fast temperature spectrometer for samples under extreme conditions.

    Science.gov (United States)

    Zhang, Dongzhou; Jackson, Jennifer M; Zhao, Jiyong; Sturhahn, Wolfgang; Alp, E Ercan; Toellner, Thomas S; Hu, Michael Y

    2015-01-01

    We have developed a multi-wavelength Fast Temperature Readout (FasTeR) spectrometer to capture a sample's transient temperature fluctuations, and reduce uncertainties in melting temperature determination. Without sacrificing accuracy, FasTeR features a fast readout rate (about 100 Hz), high sensitivity, large dynamic range, and a well-constrained focus. Complimenting a charge-coupled device spectrometer, FasTeR consists of an array of photomultiplier tubes and optical dichroic filters. The temperatures determined by FasTeR outside of the vicinity of melting are, generally, in good agreement with results from the charge-coupled device spectrometer. Near melting, FasTeR is capable of capturing transient temperature fluctuations, at least on the order of 300 K/s. A software tool, SIMFaster, is described and has been developed to simulate FasTeR and assess design configurations. FasTeR is especially suitable for temperature determinations that utilize ultra-fast techniques under extreme conditions. Working in parallel with the laser-heated diamond-anvil cell, synchrotron Mössbauer spectroscopy, and X-ray diffraction, we have applied the FasTeR spectrometer to measure the melting temperature of (57)Fe0.9Ni0.1 at high pressure.

  13. Sensitivity of summer precipitation to tropical sea surface temperatures over East Asia in the GRIMs GMP

    Science.gov (United States)

    Chang, Eun-Chul; Yeh, Sang-Wook; Hong, Song-You; Wu, Renguang

    2013-05-01

    In this study, uncoupled atmospheric general circulation model experiments are conducted to examine the sensitivity of tropical Ocean basins from the Indian Ocean to the tropical Pacific Ocean on the summer precipitation variability over East Asia. It is remarkable that the Indian Ocean basin sea surface temperature (SST) and the tropical Pacific basin SST act on summer precipitation variability over Northeast Asia and southern China quite differently. That is, SST warming in the Indian Ocean largely contributes to the increase in the amount of summer precipitation over East Asia, which is in contrast to the warming of the western tropical Pacific Ocean. Our further analysis indicates that an altered large-scale atmospheric circulation over the western tropical Pacific contributes to contrasting atmospheric motion over East Asia due to the tropics-East Asia teleconnections, which results in changes in the amount of summer precipitation due to the warming of the Indian and western tropical Pacific Oceans.

  14. Animal physiology. Summer declines in activity and body temperature offer polar bears limited energy savings.

    Science.gov (United States)

    Whiteman, J P; Harlow, H J; Durner, G M; Anderson-Sprecher, R; Albeke, S E; Regehr, E V; Amstrup, S C; Ben-David, M

    2015-07-17

    Polar bears (Ursus maritimus) summer on the sea ice or, where it melts, on shore. Although the physiology of "ice" bears in summer is unknown, "shore" bears purportedly minimize energy losses by entering a hibernation-like state when deprived of food. Such a strategy could partially compensate for the loss of on-ice foraging opportunities caused by climate change. However, here we report gradual, moderate declines in activity and body temperature of both shore and ice bears in summer, resembling energy expenditures typical of fasting, nonhibernating mammals. Also, we found that to avoid unsustainable heat loss while swimming, bears employed unusual heterothermy of the body core. Thus, although well adapted to seasonal ice melt, polar bears appear susceptible to deleterious declines in body condition during the lengthening period of summer food deprivation.

  15. Spatial and Temporal Variations in Indian Summer Monsoon Rainfall and Temperature: An Analysis Based on RegCM3 Simulations

    Science.gov (United States)

    Dash, S. K.; Mamgain, Ashu; Pattnayak, K. C.; Giorgi, F.

    2013-04-01

    Regional climate models are important tools to examine the spatial and temporal characteristics of rainfall and temperature at high resolutions. Such information has potential applications in sectors like agriculture and health. In this study, the Regional Climate Model Version 3 (RegCM3) has been integrated in the ensemble mode at 55 km resolution over India for the summer monsoon season during the years 1982-2009. Emphasis has been given on the validation of the model simulation at the regional level. In Central India, both rainfall and temperature show the best correlations with respective observed values. The model gives rise to large wet biases over Northwest and Peninsular India. RegCM3 slightly underestimates the summer monsoon precipitation over the Central and Northeast India. Nevertheless, over these regions, RegCM3 simulated rainfall is closer to the observations when compared to the other regions where rainfall is overestimated. The position of the monsoon trough simulated by the model lies to the north of its original observed position. This is similar to the usual monsoon break conditions leading to less rainfall over Central India. RegCM3 simulated surface maximum temperature shows a large negative bias over the country while the surface minimum temperature is close to the observation. Nevertheless, there is a strong correlation between the all India weighted average surface temperature simulated by RegCM3 and IMD observed values. While examining the extreme weather conditions in Central India, it is found that RegCM3 simulated frequencies of occurrence of very wet days, extremely wet days, warm days and warm nights more often as compared to those in IMD observed values. However, these are systematic biases. The model biases in the frequencies of distribution of rainfall extremes explain the wet and dry biases in different regions in the country. Overall, the inter-annual characteristics of both the rainfall and temperature extremes simulated by Reg

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

    Science.gov (United States)

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

    2016-05-01

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

  17. Changes in extreme temperature and precipitation events in the Loess Plateau (China) during 1960-2013 under global warming

    Science.gov (United States)

    Sun, Wenyi; Mu, Xingmin; Song, Xiaoyan; Wu, Dan; Cheng, Aifang; Qiu, Bing

    2016-02-01

    In recent decades, extreme climatic events have been a major issue worldwide. Regional assessments on various climates and geographic regions are needed for understanding uncertainties in extreme events' responses to global warming. The objective of this study was to assess the annual and decadal trends in 12 extreme temperature and 10 extreme precipitation indices in terms of intensity, frequency, and duration over the Loess Plateau during 1960-2013. The results indicated that the regionally averaged trends in temperature extremes were consistent with global warming. The occurrence of warm extremes, including summer days (SU), tropical nights (TR), warm days (TX90), and nights (TN90) and a warm spell duration indicator (WSDI), increased by 2.76 (P spell duration indicator (CSDI) exhibited decreases of - 3.22 (P wet-day and extremely wet-day precipitation were not significant. Large-scale atmospheric circulation indices, such as the Western Pacific Subtropical High Intensity Index (WPSHII) and Arctic Oscillation (AO), strongly influences warm/cold extremes and contributes significantly to climate changes in the Loess Plateau. The enhanced geopotential height over the Eurasian continent and increase in water vapor divergence in the rainy season have contributed to the changes of the rapid warming and consecutive drying in the Loess Plateau.

  18. Extreme late-summer drought causes neutral annual carbon balance in southwestern ponderosa pine forests and grasslands

    Science.gov (United States)

    Kolb, Thomas; Dore, Sabina; Montes-Helu, Mario

    2013-03-01

    We assessed the impacts of extreme late-summer drought on carbon balance in a semi-arid forest region in Arizona. To understand drought impacts over extremes of forest cover, we measured net ecosystem production (NEP), gross primary production (GPP), and total ecosystem respiration (TER) with eddy covariance over five years (2006-10) at an undisturbed ponderosa pine (Pinus ponderosa) forest and at a former forest converted to grassland by intense burning. Drought shifted annual NEP from a weak source of carbon to the atmosphere to a neutral carbon balance at the burned site and from a carbon sink to neutral at the undisturbed site. Carbon fluxes were particularly sensitive to drought in August. Drought shifted August NEP at the undisturbed site from sink to source because the reduction of GPP (70%) exceeded the reduction of TER (35%). At the burned site drought shifted August NEP from weak source to neutral because the reduction of TER (40%) exceeded the reduction of GPP (20%). These results show that the lack of forest recovery after burning and the exposure of undisturbed forests to late-summer drought reduce carbon sink strength and illustrate the high vulnerability of forest carbon sink strength in the southwest US to predicted increases in intense burning and precipitation variability.

  19. Evaluation of large-scale meteorological patterns associated with temperature extremes in the NARCCAP regional climate model simulations

    Science.gov (United States)

    Loikith, Paul C.; Waliser, Duane E.; Lee, Huikyo; Neelin, J. David; Lintner, Benjamin R.; McGinnis, Seth; Mearns, Linda O.; Kim, Jinwon

    2015-12-01

    Large-scale meteorological patterns (LSMPs) associated with temperature extremes are evaluated in a suite of regional climate model (RCM) simulations contributing to the North American Regional Climate Change Assessment Program. LSMPs are characterized through composites of surface air temperature, sea level pressure, and 500 hPa geopotential height anomalies concurrent with extreme temperature days. Six of the seventeen RCM simulations are driven by boundary conditions from reanalysis while the other eleven are driven by one of four global climate models (GCMs). Four illustrative case studies are analyzed in detail. Model fidelity in LSMP spatial representation is high for cold winter extremes near Chicago. Winter warm extremes are captured by most RCMs in northern California, with some notable exceptions. Model fidelity is lower for cool summer days near Houston and extreme summer heat events in the Ohio Valley. Physical interpretation of these patterns and identification of well-simulated cases, such as for Chicago, boosts confidence in the ability of these models to simulate days in the tails of the temperature distribution. Results appear consistent with the expectation that the ability of an RCM to reproduce a realistically shaped frequency distribution for temperature, especially at the tails, is related to its fidelity in simulating LMSPs. Each ensemble member is ranked for its ability to reproduce LSMPs associated with observed warm and cold extremes, identifying systematically high performing RCMs and the GCMs that provide superior boundary forcing. The methodology developed here provides a framework for identifying regions where further process-based evaluation would improve the understanding of simulation error and help guide future model improvement and downscaling efforts.

  20. [Sports and extreme conditions. Cardiovascular incidence in long term exertion and extreme temperatures (heat, cold)].

    Science.gov (United States)

    Melin, B; Savourey, G

    2001-06-30

    During ultra-endurance exercise, both increase in body temperature and dehydration due to sweat losses, lead to a decrease in central blood volume. The heart rate drift allows maintaining appropriate cardiac output, in order to satisfy both muscle perfusion and heat transfer requirements by increasing skin blood flow. The resulting dehydration can impair thermal regulation and increase the risks of serious accidents as heat stroke. Endurance events, lasting more than 8 hours, result in large sweat sodium chloride losses. Thus, ingestion of large amounts of water with poor salt intake can induce symptomatic hyponatremia (plasma sodium extreme condition.

  1. Trends in extreme temperature indices in Huang-Huai-Hai River Basin of China during 1961-2014

    Science.gov (United States)

    Wang, Gang; Yan, Denghua; He, Xiaoyan; Liu, Shaohua; Zhang, Cheng; Xing, Ziqiang; Kan, Guangyuan; Qin, Tianling; Ren, Minglei; Li, Hui

    2017-08-01

    Spatial and temporal characteristics of temperature extremes have been investigated in Huang-Huai-Hai (HHH) region based on the daily series of temperature observations from 162 meteorological stations. A total of 11 indices were used to assess the changes of temperature pattern. Linear trend analyses revealed that the daily maximum temperature (TXx) increased at α = 0.05 level with a magnitude of 0.15 °C per decade on the regional scale during the period of 1961-2014. More pronounced warming trend of the daily minimum temperature (TNn) was detected at a rate of 0.49 °C per decade (α = 0.01 level). Consequently, a decreasing trend of the temperature range of TXx and TNn (extreme temperature range) was observed. The frequency of hot days (TXf90) and annual average of warm events (warm spell duration indicator, WSDI) showed significant increasing trends, while that of cold nights (TNf10) and cold events (cold spell duration indicator, CSDI) showed opposite behaviors. Both warm winter (W-W) and hot summer (H-S) series displayed significant increasing trends at α = 0.01 confidence level. The cold winter (C-W) series showed a decreasing trend at α = 0.01 confidence level, while the cool summer (C-S) series showed a nonsignificant decreasing trend that is not passing the 90% confidence level (α = 0.1). Abrupt increments of warm­related extremes (TXx, TXf90, WSDI) have been detected since 1990s, and a steadily decreasing trend of cold related extremes (TNf10, CSDI) was found since 1970s. Ten hot summers out of 11 and nine warm winters out of 10 occurred after 1990s. Altitude has a large impact on spatial pattern of extreme temperature indices, and the urban heat island effect also has an impact on amplitude of variation in extreme temperature. Trend magnitudes are significantly larger at sites with high altitudes for warm­related indices (TXx, TXf90, WSDI), while those involving cold-related indices (TNn, TNf10) are remarkably larger for stations with low

  2. The impact of summer temperatures and heatwaves on mortality and morbidity in Perth, Australia 1994-2008.

    Science.gov (United States)

    Williams, Susan; Nitschke, Monika; Weinstein, Philip; Pisaniello, Dino L; Parton, Kevin A; Bi, Peng

    2012-04-01

    Climate change projections have drawn attention to the risks of extreme heat and the importance of public health interventions to minimise the impact. The city of Perth, Western Australia, frequently experiences hot summer conditions, with recent summers showing above average temperatures. Daily maximum and minimum temperatures, mortality, emergency department (ED) presentations and hospital admissions data were acquired for Perth for the period 1994 to 2008. Using an observed/expected analysis, the temperature thresholds for mortality were estimated at 34-36°C (maximum) and 20°C (minimum). Generalised estimating equations (GEEs) were used to estimate the percentage increase in mortality and morbidity outcomes with a 10°C increment in temperature, with adjustment for air pollutants. Effect estimates are reported as incidence rate ratios (IRRs). The health impact of heatwave days (three or more days of ≥35°C) was also investigated. A 9.8% increase in daily mortality (IRR 1.098; 95%CI: 1.007-1.196) was associated with a 10°C increase in maximum temperature above threshold. Total ED presentations increased by 4.4% (IRR 1.044; 95%CI: 1.033-1.054) and renal-related ED presentations by 10.2% (IRR 1.102; 95%CI: 1.071-1.135) per 10°C increase in maximum temperature. Heatwave days were associated with increases in daily mortality and ED presentations, while total hospital admissions were decreased on heatwave days. Public health interventions will be increasingly important to minimise the adverse health impacts of hot weather in Perth, particularly if the recent trend of rising average temperatures and more hot days continues as projected.

  3. Refining multi-model projections of temperature extremes by evaluation against land-atmosphere coupling diagnostics

    Science.gov (United States)

    Sippel, Sebastian; Zscheischler, Jakob; Mahecha, Miguel D.; Orth, Rene; Reichstein, Markus; Vogel, Martha; Seneviratne, Sonia I.

    2017-05-01

    The Earth's land surface and the atmosphere are strongly interlinked through the exchange of energy and matter. This coupled behaviour causes various land-atmosphere feedbacks, and an insufficient understanding of these feedbacks contributes to uncertain global climate model projections. For example, a crucial role of the land surface in exacerbating summer heat waves in midlatitude regions has been identified empirically for high-impact heat waves, but individual climate models differ widely in their respective representation of land-atmosphere coupling. Here, we compile an ensemble of 54 combinations of observations-based temperature (T) and evapotranspiration (ET) benchmarking datasets and investigate coincidences of T anomalies with ET anomalies as a proxy for land-atmosphere interactions during periods of anomalously warm temperatures. First, we demonstrate that a large fraction of state-of-the-art climate models from the Coupled Model Intercomparison Project (CMIP5) archive produces systematically too frequent coincidences of high T anomalies with negative ET anomalies in midlatitude regions during the warm season and in several tropical regions year-round. These coincidences (high T, low ET) are closely related to the representation of temperature variability and extremes across the multi-model ensemble. Second, we derive a land-coupling constraint based on the spread of the T-ET datasets and consequently retain only a subset of CMIP5 models that produce a land-coupling behaviour that is compatible with these benchmark estimates. The constrained multi-model simulations exhibit more realistic temperature extremes of reduced magnitude in present climate in regions where models show substantial spread in T-ET coupling, i.e. biases in the model ensemble are consistently reduced. Also the multi-model simulations for the coming decades display decreased absolute temperature extremes in the constrained ensemble. On the other hand, the differences between projected

  4. Refining multi-model projections of temperature extremes by evaluation against land–atmosphere coupling diagnostics

    Directory of Open Access Journals (Sweden)

    S. Sippel

    2017-05-01

    Full Text Available The Earth's land surface and the atmosphere are strongly interlinked through the exchange of energy and matter. This coupled behaviour causes various land–atmosphere feedbacks, and an insufficient understanding of these feedbacks contributes to uncertain global climate model projections. For example, a crucial role of the land surface in exacerbating summer heat waves in midlatitude regions has been identified empirically for high-impact heat waves, but individual climate models differ widely in their respective representation of land–atmosphere coupling. Here, we compile an ensemble of 54 combinations of observations-based temperature (T and evapotranspiration (ET benchmarking datasets and investigate coincidences of T anomalies with ET anomalies as a proxy for land–atmosphere interactions during periods of anomalously warm temperatures. First, we demonstrate that a large fraction of state-of-the-art climate models from the Coupled Model Intercomparison Project (CMIP5 archive produces systematically too frequent coincidences of high T anomalies with negative ET anomalies in midlatitude regions during the warm season and in several tropical regions year-round. These coincidences (high T, low ET are closely related to the representation of temperature variability and extremes across the multi-model ensemble. Second, we derive a land-coupling constraint based on the spread of the T–ET datasets and consequently retain only a subset of CMIP5 models that produce a land-coupling behaviour that is compatible with these benchmark estimates. The constrained multi-model simulations exhibit more realistic temperature extremes of reduced magnitude in present climate in regions where models show substantial spread in T–ET coupling, i.e. biases in the model ensemble are consistently reduced. Also the multi-model simulations for the coming decades display decreased absolute temperature extremes in the constrained ensemble. On the other hand

  5. On extreme rainfall intensity increases with air temperature

    Science.gov (United States)

    Molnar, Peter; Fatichi, Simone; Paschalis, Athanasios; Gaal, Ladislav; Szolgay, Jan; Burlando, Paolo

    2016-04-01

    The water vapour holding capacity of air increases at about 7% per degree C according to the Clausius-Clapeyron (CC) relation. This is one of the arguments why a warmer future atmosphere, being able to hold more moisture, will generate higher extreme precipitation intensities. However, several empirical studies have recently demonstrated an increase in extreme rain intensities with air temperature above CC rates, in the range 7-14% per degree C worldwide (called super-CC rates). This was observed especially for shorter duration rainfall, i.e. in hourly and finer resolution data (e.g. review in Westra et al., 2014). The super-CC rate was attributed to positive feedbacks between water vapour and the updraft dynamics in convective clouds and lateral supply (convergence) of moisture. In addition, mixing of storm types was shown to be potentially responsible for super-CC rates in empirical studies. Assuming that convective events are accompanied by lightning, we will show on a large rainfall dataset in Switzerland (30 year records of 10-min and 1-hr data from 59 stations) that while the average rate of increase in extreme rainfall intensity (95th percentile) is 6-7% in no-lightning events and 8-9% in lightning events, it is 11-13% per degree C when all events are combined (Molnar et al., 2015). These results are relevant for climate change studies which predict shifts in storm types in a warmer climate in some parts of the world. The observation that extreme rain intensity and air temperature are positively correlated has consequences for the stochastic modelling of rainfall. Most current stochastic models do not explicitly include a direct rain intensity-air temperature dependency beyond applying factors of change predicted by climate models to basic statistics of precipitation. Including this dependency explicitly in stochastic models will allow, for example in the nested modelling approach of Paschalis et al. (2014), the random cascade disaggregation routine to be

  6. Tendencies of extreme values on rainfall and temperature and its relationship with teleconnection patterns

    Science.gov (United States)

    Taboada, J. J.; Cabrejo, A.; Guarin, D.; Ramos, A. M.

    2009-04-01

    It is now very well established that yearly averaged temperatures are increasing due to anthropogenic climate change. In the area of Galicia (NW Spain) this trend has also been determined. Rainfall does not show a clear tendency in its yearly accumulated values. The aim of this work is to study different extreme indices of rainfall and temperatures analysing variability and possible trends associated to climate change. Station data for the study was provided by the CLIMA database of the regional government of Galicia (NW Spain). The definition of the extreme indices was taken from the joint CCl/CLIVAR/JCOMM Expert Team (ET) on Climate Change Detection and Indices (ETCCDI) This group has defined a set of standard extreme values to simplify intercomparison of data from different regions of the world. For the temperatures in the period 1960-2006, results show a significant increase of the number of days with maximum temperatures above the 90th percentile. Furthermore, a significant decrease of the days with maximum temperatures below the 10th percentile has been found. The tendencies of minimum temperatures are reverse: fewer nights with minimum temperatures below 10th percentile, and more with minimum temperatures above 90th percentile. Those tendencies can be observed all over the year, but are more pronounced in summer. This trend is expected to continue in the next decades because of anthropogenic climate change. We have also calculated the relationship between the above mentioned extreme values and different teleconnection patterns appearing in the North Atlantic area. Results show that local tendencies are associated with trends of EA (Eastern Atlantic) and SCA (Scandinavian) patterns. NAO (North Atlantic Oscillation) has also some relationship with these tendencies, but only related with cold days and nights in winter. Rainfall index do not show any clear tendency on the annual scale. Nevertheless, the count of days when precipitation is greater than 20mm (R20

  7. Extreme warm temperatures alter forest phenology and productivity in Europe.

    Science.gov (United States)

    Crabbe, Richard A; Dash, Jadu; Rodriguez-Galiano, Victor F; Janous, Dalibor; Pavelka, Marian; Marek, Michal V

    2016-09-01

    Recent climate warming has shifted the timing of spring and autumn vegetation phenological events in the temperate and boreal forest ecosystems of Europe. In many areas spring phenological events start earlier and autumn events switch between earlier and later onset. Consequently, the length of growing season in mid and high latitudes of European forest is extended. However, the lagged effects (i.e. the impact of a warm spring or autumn on the subsequent phenological events) on vegetation phenology and productivity are less explored. In this study, we have (1) characterised extreme warm spring and extreme warm autumn events in Europe during 2003-2011, and (2) investigated if direct impact on forest phenology and productivity due to a specific warm event translated to a lagged effect in subsequent phenological events. We found that warmer events in spring occurred extensively in high latitude Europe producing a significant earlier onset of greening (OG) in broadleaf deciduous forest (BLDF) and mixed forest (MF). However, this earlier OG did not show any significant lagged effects on autumnal senescence. Needleleaf evergreen forest (NLEF), BLDF and MF showed a significantly delayed end of senescence (EOS) as a result of extreme warm autumn events; and in the following year's spring phenological events, OG started significantly earlier. Extreme warm spring events directly led to significant (p=0.0189) increases in the productivity of BLDF. In order to have a complete understanding of ecosystems response to warm temperature during key phenological events, particularly autumn events, the lagged effect on the next growing season should be considered.

  8. Dendroclimatic Reconstruction of Summer Temperatures in Irik Valley, Mount Elbrus (Greater Caucasus

    Directory of Open Access Journals (Sweden)

    Iulian Horia HOLOBÂCĂ

    2014-11-01

    Full Text Available Recent evidence suggests an acceleration of glacier retreat in Greater Caucasus after 1980. For the same period a significant summer temperature warming trend and little or no change in precipitation variation have been observed. In this paper we seek to find similar past climatic conditions using a dendroclimatic reconstruction of summer temperatures from upper treeline sites after the Little Ice Age (LIA. Dendroclimatological sampling of Scots pine (Pinus sylvestris has been made in Irik Valley, near Elbrus glacier, and a tree-ring width (TRW chronology has been used to reconstruct May – August (MJJA temperatures back to 1830. Three warm periods were identified in the MJJA temperatures reconstructed data (1830 - 1900, but we cannot appreciate if they had the same intensity as the recent warm period

  9. Climatology and trends of summer high temperature days in India during 1969–2013

    Indian Academy of Sciences (India)

    A K Jaswal; P C S Rao; Virendra Singh

    2015-02-01

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

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

    Science.gov (United States)

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

    2015-02-01

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

  11. Relationship between alpine tourism demand and hot summer air temperatures associated with climate change

    Science.gov (United States)

    Rebetez, M.; Serquet, G.

    2010-09-01

    We quantified the impacts of hot summer air temperatures on tourism in the Swiss Alps by analyzing the relationship between temperature and overnight stays in 40 Alpine resorts. Several temperature and insolation thresholds were tested to detect their relationship to summer tourism. Our results reveal significant correlations between the number of nights spent in mountain resorts and hot temperatures at lower elevations. Alpine resorts nearest to cities are most sensitive to hot temperatures. This is probably because reactions to hot episodes take place on a short-term basis as heat waves remain relatively rare. The correlation in June is stronger compared to the other months, probably because school holidays and the peak domestic tourist demand in summer usually takes place in July and August. Our results suggest that alpine tourist resorts could benefit from hotter temperatures at lower elevations under future climates. Tourists already react on a short-term basis to hot days and spend more nights in hotels in mountain resorts. If heat waves become more regular, it seems likely that tourists choose to stay at alpine resorts more frequently and for longer periods.

  12. Long-term summer temperature reconstruction inferred from tree-ring records from the Eastern Carpathians

    Energy Technology Data Exchange (ETDEWEB)

    Popa, Ionel [Forest Research and Management Institute, Research Station for Norway Spruce Silviculture, Campulung Moldovenesc (Romania); Kern, Zoltan [Hungarian Academy of Sciences, Institute for Geochemical Research, Budapest (Hungary)

    2009-06-15

    The first 1,000 year long Carpathian tree-ring width chronology was established based on living and subfossil stone pine (Pinus cembra L.) samples from an upper timberline forest located in Calimani Mts. (Romania). Tree-ring data were standardized using the regional curve standardization method in order to preserve the low and medium frequency climate signals. The de-trended index strongly correlates with summer mean temperature both at annual and decadal scales. The Calimani summer mean temperature anomalies were reconstructed for the period ad 1163-2005 applying the rescaling method. This new climate proxy from the Carpathians shows similar fluctuations to other North Hemispheric temperature reconstructions, but with periods of distinct differences. The fingerprint of Little Ice Age in the Calimani area is visible between ad 1370 and 1630 followed by lagged cold decades in ad 1820 and 1840. The recent warming is evident only after the 1980s in our reconstruction. (orig.)

  13. Impact of summer office set air-conditioning temperature on energy consumption and thermal comfort

    Institute of Scientific and Technical Information of China (English)

    刘红; 马小磊; 高亚峰

    2009-01-01

    To explore the relationship between summer office set air-conditioning temperature and energy consumption related to air conditioning use to provide human thermal comfort,a comparison experiment was conducted in three similar offices at temperatures of 24,26 and 28 ℃ respectively. A thermal comfort questionnaire survey was conducted. It is demonstrated that air-conditioner energy consumption at the set temperature of 28 ℃ is 113% and 271% lower than at 26 ℃ and 24 ℃,respectively. A linear relationship exists between air-conditioner energy consumption and the indoor and outdoor temperature difference. When comfortably dressed,over 80% of research participants accept the set temperature of 28 ℃. The regression analysis leads to a neutral temperature of 26.2 ℃ and an acceptable temperature of 28.2 ℃ for over 80% of the research participants subjects,indicating that the current 26 ℃ set temperature for offices in summer,required by Chinese General Office of the State Council,can be increased to 28 ℃. Moreover,analysis of predicted mean vote(PMV) index shows that a set temperature of 27 ℃,not 26 ℃,is sufficiently comfortable for office staff wearing long-sleeve shirts,long pants and leather shoes.

  14. The role of the QBO in the inter-hemispheric coupling of summer mesospheric temperatures

    Directory of Open Access Journals (Sweden)

    P. J. Espy

    2011-01-01

    Full Text Available Inter-hemispheric coupling between the polar summer mesosphere and planetary-wave activity in the extra-tropical winter stratosphere has recently been inferred using Polar Mesospheric Cloud (PMC properties as a proxy for mesospheric temperature (Karlsson et al., 2007. Here we confirm these results using a ten-year time series of July mesospheric temperatures near 60° N derived from the hydroxyl (OH nightglow. In addition, we show that the time-lagged correlation between these summer mesospheric temperatures and the ECMWF winter stratospheric temperatures displays a strong Quasi-Biennial Oscillation (QBO. The sign and phase of the correlation is consistent with the QBO modulation of the extra-tropical stratospheric dynamics in the Southern Hemisphere via the Holton-Tan mechanism (Holton and Tan, 1980. This lends strength to the identification of synoptic and planetary waves as the driver of the inter-hemispheric coupling, and results in a strong QBO modulation of the polar summer mesospheric temperatures.

  15. Interannual to decadal summer drought variability over Europe and its relationship to global sea surface temperature

    Energy Technology Data Exchange (ETDEWEB)

    Ionita, M.; Lohmann, G. [Alfred Wegener Institute for Polar and Marine Research, Bremerhaven (Germany); University of Bremen, MARUM, Bremen (Germany); Rimbu, N. [Alfred Wegener Institute for Polar and Marine Research, Bremerhaven (Germany); Climed Norad, Bucharest (Romania); Bucharest University, Faculty of Physics, Bucharest (Romania); Chelcea, S. [National Institute of Hydrology and Water Management, Bucharest (Romania); Dima, M. [Alfred Wegener Institute for Polar and Marine Research, Bremerhaven (Germany); Bucharest University, Faculty of Physics, Bucharest (Romania)

    2012-01-15

    Interannual to decadal variability of European summer drought and its relationship with global sea surface temperature (SST) is investigated using the newly developed self calibrated Palmer drought severity index (scPDSI) and global sea surface temperature (SST) field for the period 1901-2002. A European drought severity index defined as the average of scPDSI over entire Europe shows quasiperiodic variations in the 2.5-5 year band as well as at 12-13 years suggesting a possible potential predictability of averaged drought conditions over Europe. A Canonical Correlation Analysis between summer scPDSI anomalies over Europe and global SST anomalies reveals the existence of three modes of coupled summer drought scPDSI patterns and winter global SST anomalies. The first scPDSI-SST coupled mode represents the long-term trends in the data which manifest in SST as warming over all oceans. The associated long-term trend in scPDSI suggests increasing drought conditions over the central part of Europe. The second mode is related to the inter-annual ENSO and decadal PDO influence on the European climate and the third one captures mainly the drought pattern associated to Atlantic Multidecadal Oscillation. The lag relationships between winter SST and summer drought conditions established in this study can provide a valuable skill for the prediction of drought conditions over Europe on interannual to decadal time scales. (orig.)

  16. PRTs and Their Bonding for Long-Duration, Extreme-Temperature Environments

    Science.gov (United States)

    Ramesham, Rajeshuni; Cucullu, Gordon C., III; Mikhaylov, Rebecca L.

    2012-01-01

    Research was conducted on the qualification of Honeywell platinum resistance thermometer (PRT) bonding for use in the Mars Science Laboratory (MSL). This is the first time these sensors will be used for Mars-related projects. Different types of PRTs were employed for the Mars Exploration Rover (MER) project, and several reliability issues were experienced, even for a shortduration mission like MER compared to MSL. Therefore, the development of a qualification process for the Honeywell PRT bonding was needed for the MSL project. Reliability of the PRT sensors, and their bonding processes, is a key element to understand the health of the hardware during all stages of the project, and particularly during surface operations on Mars. Three extreme temperature summer season cycles and three winter season cycles (total: 1983 thermal cycles) were completed, and no Honeywell PRT failures associated with the bonding process were found. Seventy-eight PRTs were bonded onto six different substrate materials using four different adhesives during the thermal cycling, which included a planetary protection cycle to +125 C for two hours, three protoflight/qualification cycles (-135 to 70 C), 1,384 summer cycles (-105 to 40 C), and 599 winter cycles (-130 to 15 C). There were no observed changes in PRT resistances, bonding characteristics, or damage identified from the package evaluation as a result of the qualification tests.

  17. Neptune at summer solstice: Zonal mean temperatures from ground-based observations, 2003-2007

    Science.gov (United States)

    Fletcher, Leigh N.; de Pater, Imke; Orton, Glenn S.; Hammel, Heidi B.; Sitko, Michael L.; Irwin, Patrick G. J.

    2014-03-01

    Imaging and spectroscopy of Neptune’s thermal infrared emission from Keck/LWS (2003), Gemini-N/MICHELLE (2005); VLT/VISIR (2006) and Gemini-S/TReCS (2007) is used to assess seasonal changes in Neptune’s zonal mean temperatures between Voyager-2 observations (1989, heliocentric longitude Ls=236°) and southern summer solstice (2005, Ls=270°). Our aim was to analyse imaging and spectroscopy from multiple different sources using a single self-consistent radiative-transfer model to assess the magnitude of seasonal variability. Globally-averaged stratospheric temperatures measured from methane emission tend towards a quasi-isothermal structure (158-164 K) above the 0.1-mbar level, and are found to be consistent with spacecraft observations of AKARI. This remarkable consistency, despite very different observing conditions, suggests that stratospheric temporal variability, if present, is <±5 K at 1 mbar and <±3 K at 0.1 mbar during this solstice period. Conversely, ethane emission is highly variable, with abundance determinations varying by more than a factor of two (from 500 to 1200 ppb at 1 mbar). The retrieved C2H6 abundances are extremely sensitive to the details of the T(p) derivation, although the underlying cause of the variable ethane emission remains unidentified. Stratospheric temperatures and ethane are found to be latitudinally uniform away from the south pole (assuming a latitudinally-uniform distribution of stratospheric methane), with no large seasonal hemispheric asymmetries evident at solstice. At low and mid-latitudes, comparisons of synthetic Voyager-era images with solstice-era observations suggest that tropospheric zonal temperatures are unchanged since the Voyager 2 encounter, with cool mid-latitudes and a warm equator and pole. A re-analysis of Voyager/IRIS 25-50 μm mapping of tropospheric temperatures and para-hydrogen disequilibrium (a tracer for vertical motions) suggests a symmetric meridional circulation with cold air rising at mid

  18. Regional amplification of projected changes in extreme temperatures strongly controlled by soil moisture-temperature feedbacks

    Science.gov (United States)

    Vogel, M. M.; Orth, R.; Cheruy, F.; Hagemann, S.; Lorenz, R.; Hurk, B. J. J. M.; Seneviratne, S. I.

    2017-02-01

    Regional hot extremes are projected to increase more strongly than global mean temperature, with substantially larger changes than 2°C even if global warming is limited to this level. We investigate the role of soil moisture-temperature feedbacks for this response based on multimodel experiments for the 21st century with either interactive or fixed (late 20th century mean seasonal cycle) soil moisture. We analyze changes in the hottest days in each year in both sets of experiments, relate them to the global mean temperature increase, and investigate processes leading to these changes. We find that soil moisture-temperature feedbacks significantly contribute to the amplified warming of the hottest days compared to that of global mean temperature. This contribution reaches more than 70% in Central Europe and Central North America. Soil moisture trends are more important for this response than short-term soil moisture variability. These results are relevant for reducing uncertainties in regional temperature projections.

  19. The impact of future summer temperature on public health in Barcelona and Catalonia, Spain

    Science.gov (United States)

    Ostro, Bart; Barrera-Gómez, Jose; Ballester, Joan; Basagaña, Xavier; Sunyer, Jordi

    2012-11-01

    Several epidemiological studies have reported associations between increases in summer temperatures and risks of premature mortality. The quantitative implications of predicted future increases in summer temperature, however, have not been extensively characterized. We have quantified these effects for the four main cities in Catalonia, Spain (Barcelona, Tarragona, Lleida, Girona). We first used case-crossover analysis to estimate the association between temperature and mortality for each of these cities for the period 1983 to 2006. These exposure-response (ER) functions were then combined with local measures of current and projected changes in population, mortality and temperature for the years 2025 and 2050. Predicted daily mean temperatures were based on the A1B greenhouse gas emission, "business-as-usual" scenario simulations derived from the ENSEMBLES project. Several different ER functions were examined and significant associations between temperature and mortality were observed for all four cities. For these four cities, the age-specific piecewise linear model predicts 520 (95%CI 340, 720) additional annual deaths attributable to the change in temperature in 2025 relative to the average from the baseline period of 1960-1990. For 2050, the estimate increases to 1,610 deaths per year during the warm season. For Catalonia as a whole, the point estimates for those two years are 720 and 2,330 deaths per year, respectively, or about 2 and 3% of the warm season. In comparing these predicted impacts with current causes of mortality, they clearly represent significant burdens to public health in Catalonia.

  20. The oasis effect and summer temperature rise in arid regions - case study in Tarim Basin

    Science.gov (United States)

    Hao, Xingming; Li, Weihong; Deng, Haijun

    2016-10-01

    This study revealed the influence of the oasis effect on summer temperatures based on MODIS Land Surface Temperature (LST) and meteorological data. The results showed that the oasis effect occurs primarily in the summer. For a single oasis, the maximum oasis cold island intensity based on LST (OCILST) was 3.82 °C and the minimum value was 2.32 °C. In terms of the annual change in OCILST, the mean value of all oases ranged from 2.47 °C to 3.56 °C from 2001 to 2013. Net radiation (Rn) can be used as a key predictor of OCILST and OCItemperature (OCI based on air temperature). On this basis, we reconstructed a long time series (1961–2014) of OCItemperature and Tbase(air temperature without the disturbance of oasis effect). Our results indicated that the reason for the increase in the observed temperatures was the significant decrease in the OCItemperature over the past 50 years. In arid regions, the data recorded in weather stations not only underestimated the mean temperature of the entire study area but also overestimated the increasing trend of the temperature. These discrepancies are due to the limitations in the spatial distribution of weather stations and the disturbance caused by the oasis effect.

  1. Extreme Environment Silicon Carbide Hybrid Temperature & Pressure Optical Sensors

    Energy Technology Data Exchange (ETDEWEB)

    Nabeel Riza

    2010-09-01

    This final report contains the main results from a 3-year program to further investigate the merits of SiC-based hybrid sensor designs for extreme environment measurements in gas turbines. The study is divided in three parts. Part 1 studies the material properties of SiC such as temporal response, refractive index change with temperature, and material thermal response reversibility. Sensor data from a combustion rig-test using this SiC sensor technology is analyzed and a robust distributed sensor network design is proposed. Part 2 of the study focuses on introducing redundancy in the sensor signal processing to provide improved temperature measurement robustness. In this regard, two distinct measurement methods emerge. A first method uses laser wavelength sensitivity of the SiC refractive index behavior and a second method that engages the Black-Body (BB) radiation of the SiC package. Part 3 of the program investigates a new way to measure pressure via a distance measurement technique that applies to hot objects including corrosive fluids.

  2. Vegetation Placement for Summer Built Surface Temperature Moderation in an Urban Microclimate

    Science.gov (United States)

    Millward, Andrew A.; Torchia, Melissa; Laursen, Andrew E.; Rothman, Lorne D.

    2014-06-01

    Urban vegetation can mitigate increases in summer air temperature by reducing the solar gain received by buildings. To quantify the temperature-moderating influence of city trees and vine-covered buildings, a total of 13 pairs of temperature loggers were installed on the surfaces of eight buildings in downtown Toronto, Canada, for 6 months during the summer of 2008. One logger in each pair was shaded by vegetation while the other measured built surface temperature in full sunlight. We investigated the temperature-moderating benefits of solitary mature trees, clusters of trees, and perennial vines using a linear-mixed model and a multiple regression analysis of degree hour difference. We then assessed the temperature-moderating effect of leaf area, plant size and proximity to building, and plant location relative to solar path. During a period of high solar intensity, we measured an average temperature differential of 11.7 °C, with as many as 10-12 h of sustained cooler built surface temperatures. Vegetation on the west-facing aspect of built structures provided the greatest temperature moderation, with maximum benefit (peak temperature difference) occurring late in the afternoon. Large mature trees growing within 5 m of buildings showed the greatest ability to moderate built surface temperature, with those growing in clusters delivering limited additional benefit compared with isolated trees. Perennial vines proved as effective as trees at moderating rise in built surface temperature to the south and west sides of buildings, providing an attractive alternative to shade trees where soil volume and space are limited.

  3. Long-term changes of South China Sea surface temperatures in winter and summer

    Science.gov (United States)

    Park, Young-Gyu; Choi, Ara

    2017-07-01

    Utilizing available atmospheric and oceanographic reanalysis data sets, the long-term trend in South China Sea (SCS) sea surface temperature (SST) between 1950 and 2008 and the governing processes are investigated. Both winter and summer SST increased by comparable amounts, but the warming patterns and the governing processes were different. Strong warming in winter occurred in a deep central area, and during summer in the southern region. In winter the net heat flux into the sea increased, contributing to the warming. The spatial pattern of the heat flux, however, was different from that of the warming. Heat flux increased over the coastal area where warming was weaker, but decreased over the deeper area where warming was stronger. The northeasterly monsoon wind weakened lowering the shoreward Ekman transport and the sea surface height gradient. The cyclonic gyre which transports cold northern water to the south weakened, thereby warming the ocean. The effect was manifested more strongly along the southward western boundary current inducing warming in the deep central part. In summer however, the net surface heat flux decreased and could not contribute to the warming. Over the southern part of the SCS, the weakening of the southwesterly summer monsoon reduced southeastward Ekman transport, which is parallel to the mean SST gradient. Southeastward cold advection due to Ekman transport was reduced, thereby warming the surface near the southeastern boundary of the SCS. Upwelling southeast of Vietnam was also weakened, raising the SST east of Vietnam contributing to the southern summer warming secondarily. The weakening of the winds in each season was the ultimate cause of the warming, but the responses of the ocean that lead to the warming were different in winter and summer.

  4. Downscaling summer rainfall in the UK from North Atlantic ocean temperatures

    Directory of Open Access Journals (Sweden)

    R. L. Wilby

    2001-01-01

    Full Text Available Annual series of three stochastic rainfall model parameters — the seasonal wet day amount (or intensity, the conditional dry–day probability (or dry–spell persistence, and the conditional wet-day probability (or wet-spell persistence — were examined using daily rainfall records for ten UK stations for the period 1901–1995. The purpose was first, to determine the extent to which these indices of summer (June–August rainfall were correlated with empirical orthogonal functions (EOFs of summer North Atlantic sea surface temperature (SST anomalies: second, to evaluate the skill of EOFs of preceding winter (December–February SSTs for summer rainfall forecasting and downscaling.Correlation analyses suggest that observed increases in summer dry-spell persistence since the 1970s coincided with positive SST anomalies in the North Atlantic. In contrast, wet-spell persistence and intensities were relatively weakly correlated with the same patterns, implying that the use of SSTs is justifiable for conditioning occurrence but not intensity parameters. Furthermore, the correlation strengths were greater for EOFs of SSTs than those reported for area-average SST anomalies, indicating that the pattern of SST anomalies conveys important information about seasonal rainfall anomalies across the UK. When EOFs of winter SSTs were used to forecast summer rainfall in Cambridge, the skill was once again greater for dry-spells than either wet-spells or intensities. However, even for dry–spells, the correlation with observations — whilst statistically significant — was still rather modest (r Keywords: North Atlantic, ocean temperatures, downscaling, rainfall, forecasting, UK

  5. Assessing the impacts of changing precipitation and temperature extremes on the current and future ecohydrology of grassland ecosystems

    Science.gov (United States)

    Brunsell, N. A.; Nippert, J. B.; Ocheltree, T.

    2012-12-01

    Extreme weather events have profound impacts on water and carbon cycling. However, events of similar magnitude may have very different impacts depending upon the timing of the event in the phenological cycle. We assess these impacts of extreme daily weather events including precipitation, maximum and minimum temperature using data collected from the Konza Prairie Long Term Ecological Research site in the central U.S. We utilize the long term weather and biomass collection data at the LTER site to examine the historical variability of extreme events and the impacts on annual carbon dynamics. Timescales of interactions between daily weather and fluxes are quantified through a multiscale information theoretic approach. In addition, we quantify the impacts of the timing and magnitude of extreme events through a Critical Climate Period (CCP) analysis. Results indicate a strong sensitivity to spring precipitation and summer temperature. Using six years of eddy covariance data, we can isolate more of the biophysical mechanisms governing the responses to extreme weather events. Of particular interest is the heat wave of July, 2011, where daily maximum temperatures were over 38 C for 24 consecutive days and resulted in drastically reduced above ground carbon allocation than in previous years. In addition, we employ the Agro-BGC model to assess the biophysical processes responsible for determining the response of water and carbon dynamics to extreme weather events. This is done by employing a stochastic weather generator with prescribed changes in annual precipitation and temperature conistent with GCM projections. Developing a more thorough understanding of extreme events and the differential responses due to the timing and magnitude of the events will potentially assist in the mitigation of future climate change.

  6. Evaluation of extreme temperature events in northern Spain based on process control charts

    Science.gov (United States)

    Villeta, M.; Valencia, J. L.; Saá, A.; Tarquis, A. M.

    2017-02-01

    Extreme climate events have recently attracted the attention of a growing number of researchers because these events impose a large cost on agriculture and associated insurance planning. This study focuses on extreme temperature events and proposes a new method for their evaluation based on statistical process control tools, which are unusual in climate studies. A series of minimum and maximum daily temperatures for 12 geographical areas of a Spanish region between 1931 and 2009 were evaluated by applying statistical process control charts to statistically test whether evidence existed for an increase or a decrease of extreme temperature events. Specification limits were determined for each geographical area and used to define four types of extreme anomalies: lower and upper extremes for the minimum and maximum anomalies. A new binomial Markov extended process that considers the autocorrelation between extreme temperature events was generated for each geographical area and extreme anomaly type to establish the attribute control charts for the annual fraction of extreme days and to monitor the occurrence of annual extreme days. This method was used to assess the significance of changes and trends of extreme temperature events in the analysed region. The results demonstrate the effectiveness of an attribute control chart for evaluating extreme temperature events. For example, the evaluation of extreme maximum temperature events using the proposed statistical process control charts was consistent with the evidence of an increase in maximum temperatures during the last decades of the last century.

  7. Need for Caution in Interpreting Daily Temperature Extremes

    Science.gov (United States)

    Sardeshmukh, P. D.; Compo, G. P.; Penland, C.

    2014-12-01

    Given the substantial anthropogenic contribution to global warming, it is tempting to seek an anthropogenic component in any unusual recent weather event, or more generally in any recent change in extreme weather statistics. We caution that such detection and attribution efforts may, however, lead to wrong conclusions if the distinctively skewed and heavy-tailed features of the probability distributions of daily weather variations are not properly accounted for. Large deviations from the mean are far more common in such a non-Gaussian world than they are in a Gaussian world. In such a world, a mean climate shift is also generally accompanied by changes in the width and shape of the probability distribution. Consequently, even the sign of the changes in tail probabilities cannot be inferred unequivocally from the mean shift. These realities further complicate the establishment of significant changes in tail probabilities from historical records of limited length and accuracy. A possible solution is to exploit the fact that the salient non-Gaussian features of the observed distributions are captured in a general class of probability distributions introduced in the meteorological literature by Sardeshmukh and Sura (2009). These distributions, called Stochastically Generated Skewed (SGS) distributions (of which Gaussian distributions are special cases), are associated with modified forms of stochastically perturbed damped linear processes, and as such represent perhaps the simplest physically based non-Gaussian prototypes of the observed distributions. Importantly, the distribution of an SGS variable remains an SGS distribution under a mean climate shift. We show further that fitting SGS distributions to all daily values in limited climate records yields extreme value distributions of block maxima with smaller sampling uncertainties than GEV distributions fitted to only the block maxima. Extreme value analysis based on SGS distributions thus provides an attractive

  8. Estimating changes in temperature extremes from millennial-scale climate simulations using generalized extreme value (GEV) distributions

    Science.gov (United States)

    Huang, Whitney K.; Stein, Michael L.; McInerney, David J.; Sun, Shanshan; Moyer, Elisabeth J.

    2016-07-01

    Changes in extreme weather may produce some of the largest societal impacts of anthropogenic climate change. However, it is intrinsically difficult to estimate changes in extreme events from the short observational record. In this work we use millennial runs from the Community Climate System Model version 3 (CCSM3) in equilibrated pre-industrial and possible future (700 and 1400 ppm CO2) conditions to examine both how extremes change in this model and how well these changes can be estimated as a function of run length. We estimate changes to distributions of future temperature extremes (annual minima and annual maxima) in the contiguous United States by fitting generalized extreme value (GEV) distributions. Using 1000-year pre-industrial and future time series, we show that warm extremes largely change in accordance with mean shifts in the distribution of summertime temperatures. Cold extremes warm more than mean shifts in the distribution of wintertime temperatures, but changes in GEV location parameters are generally well explained by the combination of mean shifts and reduced wintertime temperature variability. For cold extremes at inland locations, return levels at long recurrence intervals show additional effects related to changes in the spread and shape of GEV distributions. We then examine uncertainties that result from using shorter model runs. In theory, the GEV distribution can allow prediction of infrequent events using time series shorter than the recurrence interval of those events. To investigate how well this approach works in practice, we estimate 20-, 50-, and 100-year extreme events using segments of varying lengths. We find that even using GEV distributions, time series of comparable or shorter length than the return period of interest can lead to very poor estimates. These results suggest caution when attempting to use short observational time series or model runs to infer infrequent extremes.

  9. Performance of High Temperature Operational Amplifier, Type LM2904WH, under Extreme Temperatures

    Science.gov (United States)

    Patterson, Richard; Hammoud, Ahmad; Elbuluk, Malik

    2008-01-01

    Operation of electronic parts and circuits under extreme temperatures is anticipated in NASA space exploration missions as well as terrestrial applications. Exposure of electronics to extreme temperatures and wide-range thermal swings greatly affects their performance via induced changes in the semiconductor material properties, packaging and interconnects, or due to incompatibility issues between interfaces that result from thermal expansion/contraction mismatch. Electronics that are designed to withstand operation and perform efficiently in extreme temperatures would mitigate risks for failure due to thermal stresses and, therefore, improve system reliability. In addition, they contribute to reducing system size and weight, simplifying its design, and reducing development cost through the elimination of otherwise required thermal control elements for proper ambient operation. A large DC voltage gain (100 dB) operational amplifier with a maximum junction temperature of 150 C was recently introduced by STMicroelectronics [1]. This LM2904WH chip comes in a plastic package and is designed specifically for automotive and industrial control systems. It operates from a single power supply over a wide range of voltages, and it consists of two independent, high gain, internally frequency compensated operational amplifiers. Table I shows some of the device manufacturer s specifications.

  10. Relation between sea surface temperature anomaly in the Atlantic and summer precipitation over the Northeast China

    Institute of Scientific and Technical Information of China (English)

    白人海

    2001-01-01

    Based on global monthly average data set of sea surface temperature (SST) during 1950 -1992 and global monthly average 500 hPa height during 1950 - 1997 offered by NCAR/NCEP, the feature of SST anomaly in the Atlantic and its relation with summer precipitation over the Northeast China are analyzed. The results show that, the second eigenvector of the SST′s empirical orthogonal expanssion in winter season over the North Atlantic suggests that distribution of SST anomaly has unusual meridional difference; The location of its center is basically identical to center of significant correlation region between summer precipitation over the Northeast China and winter SST in the Atlantic. When winter SST in the North Atlantic is hot in south and cold in north, the blocking situation is stronger in the middle- high latitude. Correspondingly, the blocking high pressure in the northern North Pacific is also getting stronger,the westerlies circulation index in East Asia in next summer would be lower, asa result, more precipitation in the summer would be experienced over Northeast China and vice versa.

  11. Evaluation of Prospective Changes in Temperature Extremes for the CORDEX-Australasia Domain Using the NEX-GDDP Dataset

    Science.gov (United States)

    Turp, M. Tufan; An, Nazan; Kurnaz, M. Levent

    2017-04-01

    CORDEX-Australasia is a vast domain where comprises primarily Australia, New Zealand, and Papua New Guinea whilst it also covers the islands in the Pacific Ocean such as New Caledonia, Fiji, Tonga, Tuvalu, and Vanuatu as well. Climate of Australasia varies from tropical monsoonal and arid to moist temperate and alpine. The number of studies about the domain of Australasia is very limited and it is in urgent need of further efforts. This research points out the relationship between the climate change and temperature extremes over the domain of Australasia and it investigates the changes in the number of some specific temperature extreme indices (i.e. summer days, consecutive summer days, heat wave duration, very warm days, tropical nights, etc.) as described by the joint CCl/CLIVAR/JCOMM Expert Team (ET) on Climate Change Detection and Indices (ETCCDI). All these extreme indices were also calculated using the NASA Earth Exchange Global Daily Downscaled Projection (NEX-GDDP) dataset. In this study, all these index computations have been employed by utilizing ACCESS1-0 and MPI-ESM-MR global circulation models' bias corrected daily minimum and maximum air temperature variables, which were statistically downscaled to a 0.25 degrees x 0.25 degrees spatial resolution by the Climate Analytics Group and NASA Ames Research Center, under both medium-low and high emission trajectories (i.e. RCP4.5 and RCP8.5). Moreover, the analysis of the projected changes in the temperature extremes was applied for the period of 2081-2100 with respect to the reference period of 1986-2005. Acknowledgements: This research has been supported by Bogazici University Research Fund Grant Number 12220. Climate scenarios used were from the NEX-GDDP dataset, prepared by the Climate Analytics Group and NASA Ames Research Center using the NASA Earth Exchange, and distributed by the NASA Center for Climate Simulation (NCCS).

  12. Summer Mesosphere Temperature Distribution from Wide-Angle Polarization Measurements of the Twilight Sky

    CERN Document Server

    Ugolnikov, Oleg S

    2012-01-01

    The paper contains the results of wide-angle polarization camera (WAPC) measurements of the twilight sky background conducted in summer 2011 and 2012 at 55.2 degs.N, 37.5 degs.E, southwards from Moscow. The method of single scattering separation based on polarization data is suggested. The obtained components of scattering matrixes show the domination of Rayleigh scattering in the mesosphere for all observation days. It made possible to retrieve the altitude distribution of temperature in the mesosphere. The results are compared with the temperature data by TIMED/SABER and EOS Aura/MLS instruments for nearby dates and locations.

  13. Extreme operative temperatures are better descriptors of the thermal environment than mean temperatures.

    Science.gov (United States)

    Camacho, Agustín; Trefaut Rodrigues, Miguel; Navas, Carlos

    2015-01-01

    In ecological studies of thermal biology the thermal environment is most frequently described using the mean or other measures of central tendency in environmental temperatures. However, this procedure may hide biologically relevant thermal variation for ectotherms, potentially misleading interpretations. Extremes of operative temperatures (EOT) can help with this problem by bracketing the thermal environment of focal animals. Within this paper, we quantify how mean operative temperatures relate to the range of simultaneously available operative temperatures (a measure of error). We also show how EOT: 1) detect more thermal differences among microsites than measures of central tendency, like the mean OT, 2) allow inferring on microsite use by ectothermic animals, and 3) clarify the relationships between field operative temperatures and temperatures measured at weather stations (WS). To do that, we explored operative temperatures measured at four sites of the Brazilian Caatingas and their correspondent nearest weather stations. We found that the daily mean OT can hide temperature ranges of 41 °C simultaneously available at our study sites. In addition, EOT detected more thermal differences among microsites than central quantiles. We also show how EOT allow inferring about microsite use of ectothermic animals in a given site. Finally, the daily maximum temperature and the daily temperature range measured at WSs predicted well the minimum available field OT at localities many kilometers away. Based on our results, we recommend the use of EOT, instead of mean OT, in thermal ecology studies.

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

    Science.gov (United States)

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

    2009-09-01

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

  15. Projecting future summer mortality due to ambient ozone concentration and temperature changes

    Science.gov (United States)

    Lee, Jae Young; Lee, Soo Hyun; Hong, Sung-Chul; Kim, Ho

    2017-05-01

    Climate change is known to affect the human health both directly by increased heat stress and indirectly by altering environments, particularly by altering the rate of ambient ozone formation in the atmosphere. Thus, the risks of climate change may be underestimated if the effects of both future temperature and ambient ozone concentrations are not considered. This study presents a projection of future summer non-accidental mortality in seven major cities of South Korea during the 2020s (2016-2025) and 2050s (2046-2055) considering changes in temperature and ozone concentration, which were predicted by using the HadGEM3-RA model and Integrated Climate and Air Quality Modeling System, respectively. Four Representative Concentration Pathway (RCP) scenarios (RCP 2.6, 4.5, 6.0, and 8.5) were considered. The result shows that non-accidental summer mortality will increase by 0.5%, 0.0%, 0.4%, and 0.4% in the 2020s, 1.9%, 1.5%, 1.2%, and 4.4% in the 2050s due to temperature change compared to the baseline mortality during 2001-2010, under RCP 2.6, 4.5, 6.0, and 8.5, respectively, whereas the mortality will increase by 0.0%, 0.5%, 0.0%, and 0.5% in the 2020s, and 0.2%, 0.2%, 0.4%, and 0.6% in the 2050s due to ozone concentration change. The projection result shows that the future summer morality in South Korea is increased due to changes in both temperature and ozone, and the magnitude of ozone-related increase is much smaller than that of temperature-related increase, especially in the 2050s.

  16. Numerical Simulation of Wind and Temperature Fields over Beijing Area in Summer

    Institute of Scientific and Technical Information of China (English)

    HU Xiaoming; LIU Shuhua; WANG Yingchun; LI Ju

    2005-01-01

    The non-hydrostatic mesoscale model MM5V3 is used to simulate the wind and temperature fields of the atmospheric boundary layer over Beijing area in summer with the mesh resolution of 1 km. The simulation results show that the numerical model can successfully simulate the urban heat island effect and the wind and temperature fields which are affected by the complicated topography and urban heat island. The results show that: (1) the west area (from Haidiau to Fengtai Districts) is always the high temperature center of Beijing, where the surface temperature is about 6 K higher than the other suburbs; and (2) due to the unique topography the wind of Beijing area during the daytime is southern anabatic wind and at the night is northern katabatic wind. The results comparing well with the data from surface observation stations validate the accuracy of the simulation.

  17. Extreme temperatures, foundation species, and abrupt ecosystem change: an example from an iconic seagrass ecosystem.

    Science.gov (United States)

    Thomson, Jordan A; Burkholder, Derek A; Heithaus, Michael R; Fourqurean, James W; Fraser, Matthew W; Statton, John; Kendrick, Gary A

    2015-04-01

    Extreme climatic events can trigger abrupt and often lasting change in ecosystems via the reduction or elimination of foundation (i.e., habitat-forming) species. However, while the frequency/intensity of extreme events is predicted to increase under climate change, the impact of these events on many foundation species and the ecosystems they support remains poorly understood. Here, we use the iconic seagrass meadows of Shark Bay, Western Australia--a relatively pristine subtropical embayment whose dominant, canopy-forming seagrass, Amphibolis antarctica, is a temperate species growing near its low-latitude range limit--as a model system to investigate the impacts of extreme temperatures on ecosystems supported by thermally sensitive foundation species in a changing climate. Following an unprecedented marine heat wave in late summer 2010/11, A. antarctica experienced catastrophic (>90%) dieback in several regions of Shark Bay. Animal-borne video footage taken from the perspective of resident, seagrass-associated megafauna (sea turtles) revealed severe habitat degradation after the event compared with a decade earlier. This reduction in habitat quality corresponded with a decline in the health status of largely herbivorous green turtles (Chelonia mydas) in the 2 years following the heat wave, providing evidence of long-term, community-level impacts of the event. Based on these findings, and similar examples from diverse ecosystems, we argue that a generalized framework for assessing the vulnerability of ecosystems to abrupt change associated with the loss of foundation species is needed to accurately predict ecosystem trajectories in a changing climate. This includes seagrass meadows, which have received relatively little attention in this context. Novel research and monitoring methods, such as the analysis of habitat and environmental data from animal-borne video and data-logging systems, can make an important contribution to this framework.

  18. Labrador Sea surface temperature control on the summer weather in the Eastern Europe

    Science.gov (United States)

    Gnatiuk, Natalia; Vihma, Timo; Bobylev, Leonid

    2016-04-01

    Many studies have addressed the linkages between the Arctic Amplification and mid-latitude weather patterns. Most of them have focused on the effects of changes in sea ice, terrestrial snow or open ocean SST on the air temperature in selected mid-latitude areas. However, when analysing such potential linkages, one should be aware that from the point of view of the atmosphere it is almost the same whether the thermal forcing originates from the sea ice melt, snowmelt, or changes in SST. Most important is to quantify how the atmosphere responds to anomalies in the surface temperature and then affects weather patterns in remote areas. For this purpose, we studied the hemispheric-scale relationships between anomalies in the Northern Hemisphere Earth surface temperature (Ts) and 2-m air temperature (T2m) in mid-latitudes (Central and Eastern Europe). Using regression analyses based on the ERA-Interim reanalysis data, we assessed the said temperature relationships with focus on the lagged monthly and inter-seasonal linkages. Technically we divided the Northern Hemisphere in equal areas with a size of 15x10 degrees and calculated correlation coefficients for the monthly mean temperatures between all defined regions from one side and the Central/East European study regions from another side over the period 1979-2014. Using this approach, we found that the strongest links in the considered kind of relationships take place between spring sea surface temperature in the Labrador Sea and summer air (T2m) temperature in the Eastern Europe. In order to confirm the correlation results obtained, to identify thermal forcing factors and to assess their relative importance, we analysed the multiyear averages and anomalies of various meteorological parameters for 10 coldest and 10 warmest springs and summers in the period 1979-2014: surface pressure, total precipitation, sea-ice and total cloud cover, wind components, surface solar radiation downwards, surface heat fluxes and air

  19. Temperature, air pollution and total mortality during summers in Sydney, 1994-2004.

    Science.gov (United States)

    Hu, Wenbiao; Mengersen, Kerrie; McMichael, Anthony; Tong, Shilu

    2008-09-01

    This study investigated the effect of temperature and air pollutants on total mortality in summers in Sydney, Australia. Daily data on weather variables, mortality and air pollution for the Sydney metropolitan area from 1 January 1994 to 31 December 2004 were supplied by Australian Bureau of Meteorology, Australian Bureau of Statistics, and Environment Protection Agency of New South Wales, respectively. We examined the association of total mortality with weather indicators and air pollution using generalised additive models (GAMs). A time-series classification and regression tree (CART) model was developed to explore the interaction effects of temperature and air pollution that impacted on mortality. Our results show that the average increase in total daily mortality was 0.9% [95% confidence interval (CI): 0.6-1.3%] and 22% (95% CI: 6.4-40.5%) for a 1 degrees C increase in daily maximum temperature and 1 part per hundred million (pphm) increase in daily average concentration of sulphur dioxide (SO(2)), respectively. Time-series CART results show that maximum temperature and SO(2) on the current day had significant interaction effects on total mortality. There were 7.3% and 12.1% increases in daily average mortality when maximum temperature was over 32 degrees C and mean SO(2) exceeded 0.315 pphm, respectively. Daily maximum temperature was statistically significantly associated with daily deaths in Sydney during summers between 1994 and 2004. Elevated daily maximum temperature combined with high SO(2) concentrations appeared to have contributed to the increased mortality observed in Sydney during this period.

  20. Effects of Water Temperature on Male Fertility Alternation of the Sensitive TGMS Lines in Rice under the Simulated Low Air Temperature in High Summer

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The effects of water temperature on male fertility alternation of TGMS lines in rice were studied under the simulated low air temperature conditions in summer. The results indicate that warm water with temperature higher than the critical temperature of TGMS lines is able to keep the lines' male sterility stable under the air temperature below the critical temperature. These results provide theoretic basis for applying warm water as an effective measure to prevent the lines from the negative effects of the low air temperature occuring in summer in the course of seed production.

  1. Recent changes in daily precipitation and surface air temperature extremes in mainland Portugal, in the period 1941-2007

    Science.gov (United States)

    de Lima, M. Isabel P.; Santo, Fátima Espírito; Ramos, Alexandre M.; de Lima, João L. M. P.

    2013-06-01

    Changes in the climatology of precipitation and surface air temperature are being investigated worldwide, searching for changes in variability, the mean and extreme events (maximum and minimum). By exploring recent adjustments in the climate of mainland Portugal, particularly in the intensity, frequency and duration of extreme events, this study investigates trends in selected specific indices that are calculated from daily precipitation data from 57 and surface air temperature data from 23 measuring stations scattered across the territory. Special attention is paid to regional differences and variations in seasonality. The data cover the periods 1941-2007 for precipitation, and 1941-2006 for temperature. They are explored at the annual and seasonal scales and for different sub-periods. Results show that trends in annual precipitation indices are generally weak and, overall, not statistically significant at the 5% level. Nevertheless, a decreasing trend is revealed by regional indices of total wet-day precipitation and extreme precipitation (above the 99th percentile). Seasonal precipitation exhibits significant decreasing trends in spring precipitation, while extreme heavy precipitation events, in terms of both magnitude and frequency, have become more pronounced in autumn. Results for winter and summer suggest that the extremes have not suffered any significant aggravation. Trends for air temperature are statistically more significant and marked than for precipitation and indicate general warming across the territory. This warming trend is revealed very consistently by the time series of individual stations and regional mean temperature, and is also consistent with the findings reported in other studies for Portugal and at the European scale.

  2. Can reanalysis datasets describe the persistent temperature and precipitation extremes over China?

    Science.gov (United States)

    Zhu, Jian; Huang, Dan-Qing; Yan, Pei-Wen; Huang, Ying; Kuang, Xue-Yuan

    2016-08-01

    The persistent temperature and precipitation extremes may bring damage to the economy and human due to their intensity, duration and areal coverage. Understanding the quality of reanalysis datasets in descripting these extreme events is important for detection, attribution and model evaluation. In this study, the performances of two reanalysis datasets [the twentieth century reanalysis (20CR) and Interim ECMWF reanalysis (ERA-Interim)] in reproducing the persistent temperature and precipitation extremes in China are evaluated. For the persistent temperature extremes, the two datasets can better capture the intensity indices than the frequency indices. The increasing/decreasing trend of persistent warm/cold extremes has been reasonably detected by the two datasets, particularly in the northern part of China. The ERA-Interim better reproduces the climatology and tendency of persistent warm extremes, while the 20CR has better skill to depict the persistent cold extremes. For the persistent precipitation extremes, the two datasets have the ability to reproduce the maximum consecutive 5-day precipitation. The two datasets largely underestimate the maximum consecutive dry days over the northern part of China, while overestimate the maximum consecutive wet days over the southern part of China. For the response of the precipitation extremes against the temperature variations, the ERA-Interim has good ability to depict the relationship among persistent precipitation extremes, local persistent temperature extremes, and global temperature variations over specific regions.

  3. 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.

  4. Summer temperature trend over the past two millennia using air content in Himalayan ice

    Directory of Open Access Journals (Sweden)

    S. Hou

    2007-01-01

    Full Text Available Two Himalayan ice cores display a factor-two decreasing trend of air content over the past two millennia, in contrast to the relatively stable values in Greenland and Antarctica ice cores over the same period. Because the air content can be related with the relative frequency and intensity of melt phenomena, its variations along the Himalayan ice cores provide an indication of summer temperature trend. Our reconstruction point toward an unprecedented warming trend in the 20th century but does not depict the usual trends associated with "Medieval Warm Period" (MWP, or "Little Ice Age" (LIA.

  5. Climate change scenarios of extreme temperatures and atmospheric humidity for Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Tejeda-Martinez, A. [Departamento de Ciencias Atmosfericas, Universidad Veracruzana, Xalapa, Veracruz (Mexico)]. E-mail: atejeda@uv.mx; Conde-Alvarez, C. [Centro de Ciencias de la Atmosfera, Universidad Nacional Autonoma de Mexico, Mexico, D.F. (Mexico); Valencia-Treviso, L.E. [Departamento de Ciencias Atmosfericas, Universidad Veracruzana, Xalapa, Veracruz (Mexico)

    2008-10-15

    The following study explores climatic change scenarios of extreme temperature and atmospheric humidity for the 2020 and 2050 decades. They were created for Mexico through the GFDLR30, ECHAM4 and HadCM2 general circulation models. Base scenario conditions were associated with the normal climatological conditions for the period 1961-1990, with a database of 50 surface observatories. It was necessary to empirically estimate the missing data in approximately half of the pressure measurements. For the period 1961-1990, statistical models of the monthly means of maximum and minimum temperatures and atmospheric humidity (relative and specific) were obtained from the observed data of temperature, solar radiation and precipitation. Based on the simulations of the GFDLR30, ECHAM4 and HADCM2 models, a future scenario of monthly means of maximum and minimum temperatures and humidity in climatic change conditions was created. The results shown are for the representative months of winter (January) and summer (July). [Spanish] En este articulo se presentan escenarios de cambio climatico referidos a temperaturas extremas y humedad atmosferica para las decadas de 2020 y 2050. Fueron generados para Mexico a partir de los modelos de circulacion general GFDLR30, ECHAM4 y HADCM2. El escenario base corresponde a las normales climatologicas del periodo 1961-1990 para 50 observatorios de superficie. Para la mitad de ellos fue necesario estimar empiricamente la presion atmosferica a partir de la altitud y para la totalidad se obtuvieron modelos estadisticos de los promedios mensuales de temperaturas maxima y minima asi como de humedad atmosferica (relativa y especifica). Esos modelos estadisticos, combinados con las salidas de los modelos de circulacion general mencionados, produjeron escenarios futuros de medias mensuales de temperaturas extremas y de humedad bajo condiciones de cambio climatico. Se mostraran los resultados para un mes representativo del invierno (enero) y otro del verano

  6. CHANGES IN FREQUENCY, PERSISTENCE AND INTENSITY OF EXTREME HIGH-TEMPERATURE EVENTS IN THE ROMANIAN PLAIN

    Directory of Open Access Journals (Sweden)

    DRAGOTĂ CARMEN-SOFIA

    2015-03-01

    Full Text Available Recent summer heat waves (2003, 2010 had a strong socio-economic impact in different parts of the continent by means of crop shortfalls and forest fires. Sustained hot days became more frequent in the recent decades in many European regions, affecting human health and leading to additional deaths. This signal has been outlined in many studies conducted in Romania, suggesting that the southern region of Romania is particularly subject to large temperature increase. This work investigates the changing annual and seasonal heat waves at regional scale of the Romanian Plain, over period 1961-2014. Daily maximum temperature recorded at six weather stations available from the ECA&D project (European Climate Assessment and Datasets were analyzed. The changes in the seasonal frequency, duration and intensity of heat waves were studied using the Mann-Kendall nonparametric trend test, as recommended by the scientific expert team on climate change detection. The likelyhood of higher maximum temperatures rise, particularly after the mid 1980s, and the changes in the upper tail of the probability density functions of these temperatures, within the extreme domain (beyond the 95% percentile level, explain the persistence and intensity of heat waves. The upward trends are dominant most of the year, and many of the calculated decadal slopes were found statistically significant (relative to the 5% level, proving an ongoing and strong warming all over the region. Our findings are in good agreement with several recent studies carried out at European and national scale and pledge for further scientific analyses i.e. heat stress impact on public health and agriculture.

  7. Extreme precipitation and temperature responses to circulation patterns in current climate: statistical approaches

    NARCIS (Netherlands)

    Photiadou, C.

    2015-01-01

    Climate change is likely to influence the frequency of extreme extremes - temperature, precipitation and hydrological extremes, which implies increasing risks for flood and drought events in Europe. In current climate, European countries were often not sufficiently prepared to deal with the great so

  8. Summer Season Water Temperature Modeling under the Climate Change: Case Study for Fourchue River, Quebec, Canada

    Directory of Open Access Journals (Sweden)

    Jaewon Kwak

    2017-05-01

    Full Text Available It is accepted that human-induced climate change is unavoidable and it will have effects on physical, chemical, and biological properties of aquatic habitats. This will be especially important for cold water fishes such as trout. The objective of this study is to simulate water temperature for future periods under the climate change situations. Future water temperature in the Fourchue River (St-Alexandre-de-Kamouraska, QC, Canada were simulated by the CEQUEAU hydrological and water temperature model, using meteorological inputs from the Coupled Model Intercomparison Project Phase 5 (CMIP5 Global Circulation Models (GCMs with Representative Concentration Pathway (RCP 2.6, 4.5 and 8.5 climate change scenarios. The result of the study indicated that water temperature in June will increase 0.2–0.7 °C and that in September, median water temperature could decrease by 0.2–1.1 °C. The rise in summer water temperature may be favorable to brook trout (Salvelinus fontinalis growth, but several days over the Upper Incipient Lethal Temperature (UILT are also likely to occur. Therefore, flow regulation procedures, including cold water releases from the Morin dam may have to be considered for the Fourchue River.

  9. Evolution of extreme temperatures over western Iberia; reporting on recent changes and future scenarios

    Science.gov (United States)

    Ramos, Alexandre M.; Trigo, Ricardo M.; Santo, Fátima E.

    2010-05-01

    We report on changes in surface air temperature extremes over mainland Portugal during the period 1941-2006 using daily maximum and minimum temperatures (Tmax and Tmin) from 23 of the most reliable Portuguese station records. Here we have used indices corresponding to the number of days above the 90th and below the 10th percentile for both Tmax and Tmin. This allowed us, to compute trends for the entire period of data (1941-2006) as well as for two consecutive 31-year periods: 1945-1975 (relative cooling period) and 1976-2006 (relative warming period), based on results found by Karl et al, 2000. The most striking results are related with the last period (1976-2006) that reveal a significant increase in extreme heat events for both spring and summer seasons, and a decrease in extreme cold events in winter. In the second part of this work we present an analysis of climate change over Portugal simulated by the Hadley Centre regional climate model (HadRM3) with data obtained from Project PRUDENCE. The ability of the model to reproduce the present climate (1961-1990) is tested and evaluated. For this purpose, values of Tmax and Tmin of all 23 climatological weather stations (1961-1990 climate normals) were aggregated into a new time series. Additionally we have computed the seasonal percentiles in 1% steps (ranging from 1% to 99%). For comparison purposes we have aggregated HadRM3 values into a new time series averaging grid points located closest to the 23 climatological weather stations considered, and computed the corresponding seasonal percentiles in 1% steps. This procedure allowed an objective comparison between the two probability distributions (climatological and simulated by the model), using standard q-q plots. Finally we have evaluated changes of probability distributions for future climate projections under the IPCC emission scenarios (B2 and A2), for the period between 2071-2100 when compared to the present climate (1961-1990) simulated by the model. The

  10. Summer stream water temperature models for Great Lakes streams: New York

    Science.gov (United States)

    Murphy, Marilyn K.; McKenna, James E.; Butryn, Ryan S.; McDonald, Richard P.

    2010-01-01

    Temperature is one of the most important environmental influences on aquatic organisms. It is a primary driver of physiological rates and many abiotic processes. However, despite extensive research and measurements, synoptic estimates of water temperature are not available for most regions, limiting our ability to make systemwide and large-scale assessments of aquatic resources or estimates of aquatic species abundance and biodiversity. We used subwatershed averaging of point temperature measurements and associated multiscale landscape habitat conditions from over 3,300 lotic sites throughout New York State to develop and train artificial neural network models. Separate models predicting water temperature (in cold, cool, and warm temperature classes) within small catchment–stream order groups were developed for four modeling units, which together encompassed the entire state. Water temperature predictions were then made for each stream segment in the state. All models explained more than 90% of data variation. Elevation, riparian forest cover, landscape slope, and growing degree-days were among the most important model predictors of water temperature classes. Geological influences varied among regions. Predicted temperature distributions within stream networks displayed patterns of generally increasing temperature downstream but were patchy due to the averaging of water temperatures within stream size-classes of small drainages. Models predicted coldwater streams to be most numerous and warmwater streams to be generally associated with the largest rivers and relatively flat agricultural areas and urban areas. Model predictions provide a complete, georeferenced map of summer daytime mean stream temperature potential throughout New York State that can be used for planning and assessment at spatial scales from the stream segment class to the entire state.

  11. Temperature and summer mortality: geographical and temporal variations in four Italian cities.

    Science.gov (United States)

    Michelozzi, Paola; De Sario, Manuela; Accetta, Gabriele; de'Donato, Francesca; Kirchmayer, Ursula; D'Ovidio, Mariangela; Perucci, Carlo A

    2006-05-01

    To investigate geographical and temporal variations in the temperature-mortality relation. The relation between mortality and maximum apparent temperature (Tappmax) in 2003, 2004, and a previous reference period was explored by using segmented regression and generalised additive models. Four Italian cities (Bologna, Milano, Roma, and Torino), included in a national network of prevention programmes and heat health watch warning systems (HHWWS) were considered. Daily mortality counts of the resident population dying in each city during summer (June to September). The impact of Tappmax on mortality differed between cities and varied in the three periods analysed. The geographical heterogeneity of the J shaped relation was seen in the reference period with Tappmax thresholds ranging from 28 degrees C in Torino to 32 degrees C in Milano and Roma. In all cities, the percentage variation in mortality was greatest in 2003. In Torino and Roma a significant increase was seen also at lower Tappmax values that are usually not associated to an increase in mortality (26-28 degrees C). In summer 2004 the exposure levels were similar to the reference period; only in Torino the effect of Tappmax on mortality remained relevant even if reduced compared with 2003, while in Bologna no statistically significant effect was seen for any temperature range. The observed heterogeneous reduction in the impact of temperature on mortality from 2003 to 2004 may be partly explained by the lower levels of exposure. Changes in the ability of individuals and communities to adjust to high temperatures as a consequence of the implementation of public health interventions, based on HHWWS, characterised by a diverse effectiveness, may also have played an important part.

  12. Changes of temperature and precipitation extremes in China: past and future

    Science.gov (United States)

    Wen, Xin; Fang, Guohua; Qi, Heshuai; Zhou, Lei; Gao, Yuqin

    2016-10-01

    Historical temperature and precipitation extremes and their potential future changes are quantified and evaluated throughout the landmass of China. A statistical model of climate extremes based on generalized extreme value (GEV) distribution is applied to both historical climate data and bias correction and spatial disaggregation (BCSD) downscaled Coupled Model Inter-comparison Project phase 5 (CMIP5) projections. The results indicate relatively moderate historical warm extreme conditions in China with regional means of maximum temperature 28.9, 29.4, and 29.8 °C for 10-, 20-, and 50-year return periods, respectively, whereas the corresponding regional means of minimum temperature are -20.1, -20.8, and -21.5 °C, manifesting a downward trend northwardly with relative larger regional variations in cold extremes. The historical precipitation extremes also decline gradually from south-southeast toward northwest with significant regional differences. As for the future, the warm extremes are expected to aggravate by roughly 1.66-4.92 °C projected by CMIP5, indicating larger increasing rate and spatial differences compared to cold extremes. The extreme precipitation is projected to increase 7.9-13.4 %, the dry regions would see a larger increasing rate compared to wet regions. The increasing radiative forcing concentration would trigger upward variations in both temperature and precipitation extreme magnitudes. Also, the warm extreme changes are more sensitive to the radiative forcing concentration than the cold extremes. The CMIP5 projections basically maintain a favorable inter-model consistency in temperature and rainfall extreme simulation for the future, but the inter-model difference of warm extremes is larger than cold extremes.

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

    Science.gov (United States)

    Yang, H. W.; Ouarda, T.

    2015-12-01

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

  14. Neptune at Summer Solstice: Zonal Mean Temperatures from Ground-Based Observations 2003-2007

    CERN Document Server

    Fletcher, Leigh N; Orton, Glenn S; Hammel, Heidi B; Sitko, Michael L; Irwin, Patrick G J

    2013-01-01

    Imaging and spectroscopy of Neptune's thermal infrared emission is used to assess seasonal changes in Neptune's zonal mean temperatures between Voyager-2 observations (1989, heliocentric longitude Ls=236) and southern summer solstice (2005, Ls=270). Our aim was to analyse imaging and spectroscopy from multiple different sources using a single self-consistent radiative-transfer model to assess the magnitude of seasonal variability. Globally-averaged stratospheric temperatures measured from methane emission tend towards a quasi-isothermal structure (158-164 K) above the 0.1-mbar level, and are found to be consistent with spacecraft observations of AKARI. This remarkable consistency, despite very different observing conditions, suggests that stratospheric temporal variability, if present, is $\\pm$5 K at 1 mbar and $\\pm$3 K at 0.1 mbar during this solstice period. Conversely, ethane emission is highly variable, with abundance determinations varying by more than a factor of two. The retrieved C2H6 abundances are e...

  15. Millennium-long summer temperature variations in the European Alps as reconstructed from tree rings

    Directory of Open Access Journals (Sweden)

    C. Corona

    2010-06-01

    Full Text Available This paper presents a reconstruction of the summer temperatures over the Greater Alpine Region (44.05°–47.41° N, 6.43°–13° E during the last millennium based on a network of 38 multi-centennial larch and stone pine chronologies. Tree ring series are standardized using an Adaptative Regional Growth Curve, which attempts to remove the age effect from the low frequency variations in the series. The proxies are calibrated using the June to August mean temperatures from the HISTALP high-elevation temperature time series spanning the 1818–2003. The method combines an analogue technique, which is able to extend the too short tree-ring series, an artificial neural network technique for an optimal non-linear calibration including a bootstrap technique for calculating error assessment on the reconstruction. About 50% of the temperature variance is reconstructed. Low-elevation instrumental data back to 1760 compared to their instrumental target data reveal divergence between (warmer early instrumental measurements and (colder proxy estimates. The proxy record indicates cool conditions, from the mid-11th century to the mid-12th century, related to the Oort solar minimum followed by a short Medieval Warm Period (1200–1420. The Little Ice Age (1420–1830 appears particularly cold between 1420 and 1820 with summers that are 0.8 °C cooler than the 1901–2000 period. The new record suggests that the persistency of the late 20th century warming trend is unprecedented. It also reveals significant similarities with other alpine reconstructions.

  16. Temperature and summer mortality: geographical and temporal variations in four Italian cities

    Science.gov (United States)

    Michelozzi, Paola; De Sario, Manuela; Accetta, Gabriele; de'Donato, Francesca; Kirchmayer, Ursula; D'Ovidio, Mariangela; Perucci, Carlo A

    2006-01-01

    Study objective To investigate geographical and temporal variations in the temperature‐mortality relation. Design The relation between mortality and maximum apparent temperature (Tappmax) in 2003, 2004, and a previous reference period was explored by using segmented regression and generalised additive models. Setting Four Italian cities (Bologna, Milano, Roma, and Torino), included in a national network of prevention programmes and heat health watch warning systems (HHWWS) were considered. Participants Daily mortality counts of the resident population dying in each city during summer (June to September). Main results The impact of Tappmax on mortality differed between cities and varied in the three periods analysed. The geographical heterogeneity of the J shaped relation was seen in the reference period with Tappmax thresholds ranging from 28°C in Torino to 32°C in Milano and Roma. In all cities, the percentage variation in mortality was greatest in 2003. In Torino and Roma a significant increase was seen also at lower Tappmax values that are usually not associated to an increase in mortality (26–28°C). In summer 2004 the exposure levels were similar to the reference period; only in Torino the effect of Tappmax on mortality remained relevant even if reduced compared with 2003, while in Bologna no statistically significant effect was seen for any temperature range. Conclusions The observed heterogeneous reduction in the impact of temperature on mortality from 2003 to 2004 may be partly explained by the lower levels of exposure. Changes in the ability of individuals and communities to adjust to high temperatures as a consequence of the implementation of public health interventions, based on HHWWS, characterised by a diverse effectiveness, may also have played an important part. PMID:16614332

  17. Millennium-long summer temperature variations in the European Alps as reconstructed from tree rings

    Directory of Open Access Journals (Sweden)

    C. Corona

    2008-10-01

    Full Text Available This paper presents a reconstruction of the summer temperatures over the Greater Alpine Region (44.05°–47.41° N, 6.43°–13° E during the last millennium based on a network of 36 multi-centennial larch and stone pine chronologies. Tree ring series are standardized using an Adaptative Regional Growth Curve, which attempts to remove the age effect from the low frequency variations in the series. The proxies are calibrated using the June to August mean temperatures from the HISTALP high-elevation temperature time series spanning the 1818–2003. The method combines an analogue technique, which is able to extend the too short tree-ring series, an artificial neural network technique for an optimal non-linear calibration including a bootstrap technique for calculating error assessment on the reconstruction. About 50% of the temperature variance is reconstructed. Low-elevation instrumental data back to 1760 compared to their instrumental target data reveal divergence between (warmer early instrumental measurements and (colder proxy estimates. The proxy record indicates cool conditions, from the mid-11th century to the mid-12th century, related to the Oort solar minimum followed by a short Medieval Warm Period (1200–1420. The Little Ice Age (1420–1830 appears particularly cold between 1420 and 1820 with summers are 0.8°C cooler than the 1901–2000 period. The new record suggests that the persistency of the late 20th century warming trend is unprecedented. It also reveals significant similarities with other alpine reconstructions.

  18. Oral temperatures of the elderly in nursing homes in summer and winter in relation to activities of daily living

    Science.gov (United States)

    Nakamura, K.; Tanaka, Masatoshi; Motohashi, Yutaka; Maeda, Akira

    This study was conducted to clarify the seasonal difference in body temperature in summer and winter, and to document the thermal environment of the elderly living in nursing homes. The subjects were 57 healthy elderly people aged >=63 years living in two nursing homes in Japan. One of the homes was characterized by subjects with low levels of activities of daily living (ADL). Oral temperatures were measured in the morning and afternoon, with simultaneous recording of ambient temperature and relative humidity. Oral temperatures in summer were higher than in winter, with statistically significant differences (Pelderly are lower in winter than summer, particularly in physically inactive people. It appears that those with low levels of ADL are more vulnerable to large changes in ambient temperature.

  19. The role of synoptic and intraseasonal anomalies on the life cycle of rainfall extremes over South America: non-summer conditions

    Science.gov (United States)

    Hirata, Fernando E.; Grimm, Alice M.

    2016-09-01

    Previous study showed that the interaction of synoptic disturbances with intraseasonal anomalies is important for heavy rainfall in the South Atlantic Convergence Zone and the La Plata basin during the austral summer. Here, we conduct similar analysis to study the evolution of rainfall extremes during austral spring (SON), fall (MAM) and winter (JJA). A relatively homogeneous region over southeastern South America, whose limits change little from season to season, is heavily affected by extreme precipitation events, as indicated by the value of the 95th percentile of daily rainfall, higher during the spring season (16.94 mm day-1) and lower in winter (13.79 mm day-1). From 1979 to 2013, extreme rainfall events are more frequent in spring (131 events) and less frequent in fall (112 events). Similar to summertime extreme events, synoptic-scale waves continue to be the main drivers of extreme precipitation over the region. The interaction between these waves and intraseasonal anomalies during the development of rainfall extremes over southeastern South America is observed especially during neutral ENSO and La Niña conditions. Warm ENSO phases tend to favor more frequent extremes in all three seasons and extreme events during El Niños are associated with synoptic waves, with no significant interaction with intraseasonal anomalies.

  20. The Peak Structure and Future Changes of the Relationships Between Extreme Precipitation and Temperature

    Science.gov (United States)

    Wang, Guiling; Wang, Dagang; Trenberth, Kevin E.; Erfanian, Amir; Yu, Miao; Bosilovich, Michael G.; Parr, Dana T.

    2017-01-01

    Theoretical models predict that, in the absence of moisture limitation, extreme precipitation intensity could exponentially increase with temperatures at a rate determined by the Clausius-Clapeyron (C-C) relationship. Climate models project a continuous increase of precipitation extremes for the twenty-first century over most of the globe. However, some station observations suggest a negative scaling of extreme precipitation with very high temperatures, raising doubts about future increase of precipitation extremes. Here we show for the present-day climate over most of the globe,the curve relating daily precipitation extremes with local temperatures has a peak structure, increasing as expected at the low medium range of temperature variations but decreasing at high temperatures. However, this peak-shaped relationship does not imply a potential upper limit for future precipitation extremes. Climate models project both the peak of extreme precipitation and the temperature at which it peaks (T(sub peak)) will increase with warming; the two increases generally conform to the C-C scaling rate in mid- and high-latitudes,and to a super C-C scaling in most of the tropics. Because projected increases of local mean temperature (T(sub mean)) far exceed projected increases of T(sub peak) over land, the conventional approach of relating extreme precipitation to T(sub mean) produces a misleading sub-C-C scaling rate.

  1. Relationship between the Late Spring NAO and Summer Extreme Precipitation Frequency in the Middle and Lower Reaches of the Yangtze River

    Institute of Scientific and Technical Information of China (English)

    TTIAN Bao-Qiang; FAN Ke

    2012-01-01

    The relationship between the late spring North Atlantic Oscillation (NAO) and the summer extreme precipitation frequency (EPF) in the middle and lower reaches of the Yangtze River Valley (MLYRV) is examined using an NECP/NCAR reanalysis dataset and daily precipitation data from 74 stations in the MLYRV. The results show a significant negative correlation between the May NAO index and the EPF over the MLYRV in the subsequent summer. In positive EPF index years, the East Asian westerly jet shifts farther southward, and two blocking high positive anomalies appear over the Sea of Okhotsk and the Ural Mountains. These anomalies are favorable to the cold air from the mid-high latitudes invading the Yangtze River Valley (YRV). The moisture convergence and the ascending motion dominate the MLYRV. The above patterns are reversed in negative EPF index years. A wave train pattern that originates from the North Atlantic extends eastward to the Mediterranean and then moves to the Tibetan Plateau and from there to the YRV, which is an important link in the May NAO and the summer extreme precipitation in the MLYRV. The wave train may be aroused by the tripole pattern of the SST, which can explain why the May NAO affects the summer EPF in the MLYRV.

  2. Extreme temperature and oil contamination shape the relative abundance of copepod species in the Arctic

    DEFF Research Database (Denmark)

    Dinh, Khuong Van; Nielsen, Torkel Gissel

    is of north Atlantic origin. Pyrene is one of the most toxic components of crude oil to marine copepods. The temperatures of 2, 6 and 10°C represent the mean sea water temperature, the 4°C increase in mean temperature by 2100 as predicted by IPCC scenario RCP8.5 (2013) and the extreme sea water temperature...

  3. Sensitivity of Asian Summer Monsoon precipitation to tropical sea surface temperature anomalies

    Science.gov (United States)

    Fan, Lei; Shin, Sang-Ik; Liu, Zhengyu; Liu, Qinyu

    2016-10-01

    Sensitivity of Asian Summer Monsoon (ASM) precipitation to tropical sea surface temperature (SST) anomalies was estimated from ensemble simulations of two atmospheric general circulation models (GCMs) with an array of idealized SST anomaly patch prescriptions. Consistent sensitivity patterns were obtained in both models. Sensitivity of Indian Summer Monsoon (ISM) precipitation to cooling in the East Pacific was much weaker than to that of the same magnitude in the local Indian-western Pacific, over which a meridional pattern of warm north and cold south was most instrumental in increasing ISM precipitation. This indicates that the strength of the ENSO-ISM relationship is due to the large-amplitude East Pacific SST anomaly rather than its sensitivity value. Sensitivity of the East Asian Summer Monsoon (EASM), represented by the Yangtze-Huai River Valley (YHRV, also known as the meiyu-baiu front) precipitation, is non-uniform across the Indian Ocean basin. YHRV precipitation was most sensitive to warm SST anomalies over the northern Indian Ocean and the South China Sea, whereas the southern Indian Ocean had the opposite effect. This implies that the strengthened EASM in the post-Niño year is attributable mainly to warming of the northern Indian Ocean. The corresponding physical links between these SST anomaly patterns and ASM precipitation were also discussed. The relevance of sensitivity maps was justified by the high correlation between sensitivity-map-based reconstructed time series using observed SST anomaly patterns and actual precipitation series derived from ensemble-mean atmospheric GCM runs with time-varying global SST prescriptions during the same period. The correlation results indicated that sensitivity maps derived from patch experiments were far superior to those based on regression methods.

  4. Temperature and precipitation extremes in century-long gridded observations, reanalyses, and atmospheric model simulations

    Science.gov (United States)

    Donat, Markus G.; Alexander, Lisa V.; Herold, Nicholas; Dittus, Andrea J.

    2016-10-01

    Knowledge about long-term changes in climate extremes is vital to better understand multidecadal climate variability and long-term changes and to place today's extreme events in a historical context. While global changes in temperature and precipitation extremes since the midtwentieth century are well studied, knowledge about century-scale changes is limited. This paper analyses a range of largely independent observations-based data sets covering 1901-2010 for long-term changes and interannual variability in daily scale temperature and precipitation extremes. We compare across data sets for consistency to ascertain our confidence in century-scale changes in extremes. We find consistent warming trends in temperature extremes globally and in most land areas over the past century. For precipitation extremes we find global tendencies toward more intense rainfall throughout much of the twentieth century; however, local changes are spatially more variable. While global time series of the different data sets agree well after about 1950, they often show different changes during the first half of the twentieth century. In regions with good observational coverage, gridded observations and reanalyses agree well throughout the entire past century. Simulations with an atmospheric model suggest that ocean temperatures and sea ice may explain up to about 50% of interannual variability in the global average of temperature extremes, and about 15% in the global average of moderate precipitation extremes, but local correlations are mostly significant only in low latitudes.

  5. Causes and consequences of past and projected Scandinavian summer temperatures, 500-2100 AD.

    Directory of Open Access Journals (Sweden)

    Ulf Büntgen

    Full Text Available Tree rings dominate millennium-long temperature reconstructions and many records originate from Scandinavia, an area for which the relative roles of external forcing and internal variation on climatic changes are, however, not yet fully understood. Here we compile 1,179 series of maximum latewood density measurements from 25 conifer sites in northern Scandinavia, establish a suite of 36 subset chronologies, and analyse their climate signal. A new reconstruction for the 1483-2006 period correlates at 0.80 with June-August temperatures back to 1860. Summer cooling during the early 17th century and peak warming in the 1930s translate into a decadal amplitude of 2.9°C, which agrees with existing Scandinavian tree-ring proxies. Climate model simulations reveal similar amounts of mid to low frequency variability, suggesting that internal ocean-atmosphere feedbacks likely influenced Scandinavian temperatures more than external forcing. Projected 21st century warming under the SRES A2 scenario would, however, exceed the reconstructed temperature envelope of the past 1,500 years.

  6. Protein stability and enzyme activity at extreme biological temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Feller, Georges, E-mail: gfeller@ulg.ac.b [Laboratory of Biochemistry, Centre for Protein Engineering, Institute of Chemistry B6a, University of Liege, B-4000 Liege (Belgium)

    2010-08-18

    Psychrophilic microorganisms thrive in permanently cold environments, even at subzero temperatures. To maintain metabolic rates compatible with sustained life, they have improved the dynamics of their protein structures, thereby enabling appropriate molecular motions required for biological activity at low temperatures. As a consequence of this structural flexibility, psychrophilic proteins are unstable and heat-labile. In the upper range of biological temperatures, thermophiles and hyperthermophiles grow at temperatures > 100 {sup 0}C and synthesize ultra-stable proteins. However, thermophilic enzymes are nearly inactive at room temperature as a result of their compactness and rigidity. At the molecular level, both types of extremophilic proteins have adapted the same structural factors, but in opposite directions, to address either activity at low temperatures or stability in hot environments. A model based on folding funnels is proposed accounting for the stability-activity relationships in extremophilic proteins. (topical review)

  7. Teleconnections between Ethiopian summer rainfall and sea surface temperature: Part I - observation and modelling

    Energy Technology Data Exchange (ETDEWEB)

    Diro, G.T. [The Abdus salam International Centre for Theoretical Physics, Earth System Physics section, Trieste (Italy); University of Reading, Department of Meteorology, Reading (United Kingdom); Grimes, D.I.F.; Black, E. [University of Reading, Department of Meteorology, Reading (United Kingdom)

    2011-07-15

    In this study, the oceanic regions that are associated with anomalous Ethiopian summer rains were identified and the teleconnection mechanisms that give rise to these associations have been investigated. Because of the complexities of rainfall climate in the horn of Africa, Ethiopia has been subdivided into six homogeneous rainfall zones and the influence of SST anomalies was analysed separately for each zone. The investigation made use of composite analysis and modelling experiments. Two sets of composites of atmospheric fields were generated, one based on excess/deficit rainfall anomalies and the other based on warm/cold SST anomalies in specific oceanic regions. The aim of the composite analysis was to determine the link between SST and rainfall in terms of large scale features. The modelling experiments were intended to explore the causality of these linkage. The results show that the equatorial Pacific, the midlatitude northwest Pacific and the Gulf of Guinea all exert an influence on the summer rainfall in various part of the country. The results demonstrate that different mechanisms linked to sea surface temperature control variations in rainfall in different parts of Ethiopia. This has important consequences for seasonal forecasting models which are based on statistical correlations between SST and seasonal rainfall totals. It is clear that such statistical models should take account of the local variations in teleconnections. (orig.)

  8. Probabilistic models for assessment of extreme temperatures and relative humidity in Lithuania

    Science.gov (United States)

    Alzbutas, Robertas; Šeputytė, Ilona

    2015-04-01

    Extreme temperatures are fairly common natural phenomenon in Lithuania. They have mainly negative effects both on the environment and humans. Thus there are important to perform probabilistic and statistical analyzes of possibly extreme temperature values and their time-dependant changes. This is especially important in areas where technical objects (sensitive to the extreme temperatures) are foreseen to be constructed. In order to estimate the frequencies and consequences of possible extreme temperatures, the probabilistic analysis of the event occurrence and its uncertainty has been performed: statistical data have been collected and analyzed. The probabilistic analysis of extreme temperatures in Lithuanian territory is based on historical data taken from Lithuanian Hydrometeorology Service, Dūkštas Meteorological Station, Lithuanian Energy Institute and Ignalina NNP Environmental Protection Department of Environmental Monitoring Service. The main objective of performed work was the probabilistic assessment of occurrence and impact of extreme temperature and relative humidity occurring in whole Lithuania and specifically in Dūkštas region where Ignalina Nuclear Power Plant is closed for decommissioning. In addition, the other purpose of this work was to analyze the changes of extreme temperatures. The probabilistic analysis of extreme temperatures increase in Lithuanian territory was based on more than 50 years historical data. The probabilistic assessment was focused on the application and comparison of Gumbel, Weibull and Generalized Value (GEV) distributions, enabling to select a distribution, which has the best fit for data of extreme temperatures. In order to assess the likelihood of extreme temperatures different probabilistic models were applied to evaluate the probability of exeedance of different extreme temperatures. According to the statistics and the relationship between return period and probabilities of temperatures the return period for 30

  9. Anomalous Circulation Patterns in Association with Two Types of Daily Precipitation Extremes over Southeastern China during Boreal Summer

    Institute of Scientific and Technical Information of China (English)

    李明刚; 管亮勇; 金大超; 韩洁; 张茜

    2016-01-01

    Based on the daily rainfall data from China Meteorological Administration, the tropical cyclone (TC) best track data from Japan Meteorological Agency, and the NCEP-NCAR reanalysis data from NOAA, regional mean daily precipitation extreme (RDPE) events over southeastern China (specifically, the Fujian–Jiangxi region (FJR)) and the associated circulation anomalies are investigated. For the summers of 1979–2011, a total of 105 RDPE events are identified, among which 35 are TC-influenced (TCIn-RDPE) and 70 are TC-free events (TCFr-RDPE). Distinct differences between these two types of RDPEs are found in both their statistical features and the related circulation patterns. TCFr-RDPEs usually occur in June, while TCIn-RDPEs mainly take place during July–August. When TCFr-RDPEs happen, a center of the anomalous cyclonic circulation is observed over the FJR, with an anomalous anticyclonic circulation to the south of this region. The warm/moist air flows from the South China Sea (SCS) and western Pacific meet with colder air from the north, forming a narrow convergent belt of water vapor over the FJR. Simultaneously, positive diabatic forcing anomalies are observed over the FJR, whereas negative anomalies appear over both its south and north sides, facilitating the formation and maintenance of the cyclonic circulation anomaly, as well as the upward motion of the atmosphere, over the FJR. When TCIn-RDPEs occur, southeastern China is dominated by a TC-related stronger anomalous cyclonic circulation. An anomalous anticyclonic circulation in the mid and high latitudes north of the FJR exists in the mid and upper troposphere, opposite to the situation during TCFr-RDPE events. Abundant warm/wet air is carried into the FJR from both the Indian Ocean and the SCS, leading to a large amount of latent heat release over the FJR and inducing strong ascending motion there. Furthermore, large differences are also found in the manifestation of Rossby wave energy propagation between

  10. Anomalous circulation patterns in association with two types of daily precipitation extremes over southeastern China during boreal summer

    Science.gov (United States)

    Li, Minggang; Guan, Zhaoyong; Jin, Dachao; Han, Jie; Zhang, Qian

    2016-04-01

    Based on the daily rainfall data from China Meteorological Administration, the tropical cyclone (TC) best track data from Japan Meteorological Agency, and the NCEP-NCAR reanalysis data from NOAA, regional mean daily precipitation extreme (RDPE) events over southeastern China (specifically, the Fujian-Jiangxi region (FJR)) and the associated circulation anomalies are investigated. For the summers of 1979-2011, a total of 105 RDPE events are identified, among which 35 are TC-influenced (TCIn-RDPE) and 70 are TC-free events (TCFr-RDPE). Distinct differences between these two types of RDPEs are found in both their statistical features and the related circulation patterns. TCFr-RDPEs usually occur in June, while TCIn-RDPEs mainly take place during July-August. When TCFr-RDPEs happen, a center of the anomalous cyclonic circulation is observed over the FJR, with an anomalous anticyclonic circulation to the south of this region. The warm/moist air flows from the South China Sea (SCS) and western Pacific meet with colder air from the north, forming a narrow convergent belt of water vapor over the FJR. Simultaneously, positive diabatic forcing anomalies are observed over the FJR, whereas negative anomalies appear over both its south and north sides, facilitating the formation and maintenance of the cyclonic circulation anomaly, as well as the upward motion of the atmosphere, over the FJR. When TCIn-RDPEs occur, southeastern China is dominated by a TC-related stronger anomalous cyclonic circulation. An anomalous anticyclonic circulation in the mid and high latitudes north of the FJR exists in the mid and upper troposphere, opposite to the situation during TCFr-RDPE events. Abundant warm/wet air is carried into the FJR from both the Indian Ocean and the SCS, leading to a large amount of latent heat release over the FJR and inducing strong ascending motion there. Furthermore, large differences are also found in the manifestation of Rossby wave energy propagation between these

  11. Scaling precipitation extremes with temperature in the Mediterranean: past climate assessment and projection in anthropogenic scenarios

    Science.gov (United States)

    Drobinski, Philippe; Silva, Nicolas Da; Panthou, Gérémy; Bastin, Sophie; Muller, Caroline; Ahrens, Bodo; Borga, Marco; Conte, Dario; Fosser, Giorgia; Giorgi, Filippo; Güttler, Ivan; Kotroni, Vassiliki; Li, Laurent; Morin, Efrat; Önol, Bariş; Quintana-Segui, Pere; Romera, Raquel; Torma, Csaba Zsolt

    2016-03-01

    In this study we investigate the scaling of precipitation extremes with temperature in the Mediterranean region by assessing against observations the present day and future regional climate simulations performed in the frame of the HyMeX and MED-CORDEX programs. Over the 1979-2008 period, despite differences in quantitative precipitation simulation across the various models, the change in precipitation extremes with respect to temperature is robust and consistent. The spatial variability of the temperature-precipitation extremes relationship displays a hook shape across the Mediterranean, with negative slope at high temperatures and a slope following Clausius-Clapeyron (CC)-scaling at low temperatures. The temperature at which the slope of the temperature-precipitation extreme relation sharply changes (or temperature break), ranges from about 20 °C in the western Mediterranean to relationship is close to CC-scaling at temperatures below the temperature break, while at high temperatures, the negative slope is close, but somewhat flatter or steeper, than in the current climate depending on the model. Overall, models predict more intense precipitation extremes in the future. Adjusting the temperature-precipitation extremes relationship in the present climate using the CC law and the temperature shift in the future allows the recovery of the temperature-precipitation extremes relationship in the future climate. This implies negligible regional changes of relative humidity in the future despite the large warming and drying over the Mediterranean. This suggests that the Mediterranean Sea is the primary source of moisture which counteracts the drying and warming impacts on relative humidity in parts of the Mediterranean region.

  12. Electronic Components and Circuits for Extreme Temperature Environments

    Science.gov (United States)

    Patterson, Richard L.; Hammoud, Ahmad; Dickman, John E.; Gerber, Scott

    2003-01-01

    Planetary exploration missions and deep space probes require electrical power management and control systems that are capable of efficient and reliable operation in very low temperature environments. Presently, spacecraft operating in the cold environment of deep space carry a large number of radioisotope heating units in order to maintain the surrounding temperature of the on-board electronics at approximately 20 C. Electronics capable of operation at cryogenic temperatures will not only tolerate the hostile environment of deep space but also reduce system size and weight by eliminating or reducing the radioisotope heating units and their associate structures; thereby reducing system development as well as launch costs. In addition, power electronic circuits designed for operation at low temperatures are expected to result in more efficient systems than those at room temperature. This improvement results from better behavior and tolerance in the electrical and thermal properties of semiconductor and dielectric materials at low temperatures. The Low Temperature Electronics Program at the NASA Glenn Research Center focuses on research and development of electrical components, circuits, and systems suitable for applications in the aerospace environment and deep space exploration missions. Research is being conducted on devices and systems for reliable use down to cryogenic temperatures. Some of the commercial-off-the-shelf as well as developed components that are being characterized include switching devices, resistors, magnetics, and capacitors. Semiconductor devices and integrated circuits including digital-to-analog and analog-to-digital converters, DC/DC converters, operational amplifiers, and oscillators are also being investigated for potential use in low temperature applications. An overview of the NASA Glenn Research Center Low Temperature Electronic Program will be presented in this paper. A description of the low temperature test facilities along with

  13. The association of extreme temperatures and the incidence of tuberculosis in Japan

    Science.gov (United States)

    Onozuka, Daisuke; Hagihara, Akihito

    2015-08-01

    Seasonal variation in the incidence of tuberculosis (TB) has been widely assumed. However, few studies have investigated the association between extreme temperatures and the incidence of TB. We collected data on cases of TB and mean temperature in Fukuoka, Japan for 2008-2012 and used time-series analyses to assess the possible relationship of extreme temperatures with TB incident cases, adjusting for seasonal and interannual variation. Our analysis revealed that the occurrence of extreme heat temperature events resulted in a significant increase in the number of TB cases (relative risk (RR) 1.20, 95 % confidence interval (CI) 1.01-1.43). We also found that the occurrence of extreme cold temperature events resulted in a significant increase in the number of TB cases (RR 1.23, 95 % CI 1.05-1.45). Sex and age did not modify the effect of either heat or cold extremes. Our study provides quantitative evidence that the number of TB cases increased significantly with extreme heat and cold temperatures. The results may help public health officials predict extreme temperature-related TB incidence and prepare for the implementation of preventive public health interventions.

  14. The GOCF/AWAP system - forecasting temperature extremes

    Energy Technology Data Exchange (ETDEWEB)

    Fawcett, Robert [National Climate Centre, Australian Bureau of Meteorology, Docklands, Victoria 3008 (Australia); Hume, Timothy, E-mail: r.fawcett@bom.gov.a, E-mail: t.hume@bom.gov.a [Centre for Australian Weather and Climate Research, Australian Bureau of Meteorology, Docklands, Victoria 3008 (Australia)

    2010-08-15

    Gridded hourly temperature forecasts from the Bureau of Meteorology's Gridded Operational Consensus Forecasting (GOCF) system are combined in real time with the Australian Water Availability Project (AWAP) gridded daily temperature analyses to produce gridded daily maximum and minimum temperature forecasts with lead times from one to five days. These forecasts are compared against the historical record of AWAP daily temperature analyses (1911 to present), to identify regions where record or near-record temperatures are predicted to occur. This paper describes the GOCF/AWAP system, showing how the daily maximum and minimum temperature forecasts are prepared from the hourly forecasts, and how they are bias-corrected in real time using the AWAP analyses, against which they are subsequently verified. Using monthly climatologies of long-term daily mean, standard deviation and all-time highest and lowest on record, derived forecast products (for both maximum and minimum temperature) include ordinary and standardised anomalies, 'forecast - highest on record' and 'forecast - lowest on record'. Compensation for the climatological variation across the country is achieved in these last two products, which provide the necessary guidance as to whether or not record-breaking temperatures are expected, by expressing the forecast departure from the previous record in both {sup 0}C and standard deviations.

  15. The GOCF/AWAP system - forecasting temperature extremes

    Science.gov (United States)

    Fawcett, Robert; Hume, Timothy

    2010-08-01

    Gridded hourly temperature forecasts from the Bureau of Meteorology's Gridded Operational Consensus Forecasting (GOCF) system are combined in real time with the Australian Water Availability Project (AWAP) gridded daily temperature analyses to produce gridded daily maximum and minimum temperature forecasts with lead times from one to five days. These forecasts are compared against the historical record of AWAP daily temperature analyses (1911 to present), to identify regions where record or near-record temperatures are predicted to occur. This paper describes the GOCF/AWAP system, showing how the daily maximum and minimum temperature forecasts are prepared from the hourly forecasts, and how they are bias-corrected in real time using the AWAP analyses, against which they are subsequently verified. Using monthly climatologies of long-term daily mean, standard deviation and all-time highest and lowest on record, derived forecast products (for both maximum and minimum temperature) include ordinary and standardised anomalies, "forecast - highest on record" and "forecast - lowest on record". Compensation for the climatological variation across the country is achieved in these last two products, which provide the necessary guidance as to whether or not record-breaking temperatures are expected, by expressing the forecast departure from the previous record in both °C and standard deviations.

  16. Northern China maximum temperature in the summer of 1743:A historical event of burning summer in a relatively warm climate background

    Institute of Scientific and Technical Information of China (English)

    ZHANG De'er; Demaree Gaston

    2004-01-01

    In the context of historical climate records of China and early meteorological measurements of Beijing discovered recently in Europe, a study is undertaken on the 1743 hottest summer of north China over the last 700 a, covering Beijing, Tianjin, and the provinces of Hebei, Shanxi and Shandong, with the highest temperature reaching 44.4℃ in July 1743 in Beijing, in excess of the maximum climate record in the 20th century. Results show that the related weather/climate features of the 1743 heat wave, e.g., flood/ drought distribution and Meiyu activity and the external forcings, such as solar activity and equatorial Pacific SST condition are the same as those of the 1942 and 1999 heat events. It is noted that the 1743 burning summer event occurs in a relatively warm climate background prior to the Industrial Revolution, with a lower level of CO2 release.

  17. The impact of temperature changes on summer time ozone and its' precursors in the Eastern Mediterranean

    Directory of Open Access Journals (Sweden)

    U. Im

    2011-02-01

    Full Text Available Changes in temperature due to variability in meteorology and climate change are expected to significantly impact atmospheric composition. The Mediterranean is a climate sensitive region and includes megacities like Istanbul and large urban agglomerations such as Athens. The effect of temperature changes on gaseous air pollutant levels and the atmospheric processes that are controlling them in the Eastern Mediterranean are here investigated. The WRF/CMAQ mesoscale modeling system is used, coupled with the MEGAN model for the processing of biogenic volatile organic compound emissions. A set of temperature perturbations (spanning from 1 to 5 K is applied on a base case simulation corresponding to July 2004. The results indicate that the Eastern Mediterranean basin acts as a reservoir of pollutants and their precursor emissions from large urban agglomerations. During summer, chemistry is a major sink at these urban areas near the surface, and a minor contributor at downwind areas. On average, the atmospheric processes are more effective within the first 1000 m. The response rate of biogenic emissions to temperature changes is calculated to be 9±3% K−1. Ozone concentrations respond almost linearly to the changes in the ambient temperature with rates of 1±0.1 ppb O3 K−1 for all studied urban and receptor stations except for Istanbul, where a 0.4±0.1 ppb O3 K−1 change rate is calculated, which is almost half of the domain-averaged increase of 0.9±0.1 ppb O3 K−1. The computed changes in atmospheric processes are also linearly related with temperature changes.

  18. The impact of temperature changes on summer time ozone and its precursors in the Eastern Mediterranean

    Directory of Open Access Journals (Sweden)

    U. Im

    2011-04-01

    Full Text Available Changes in temperature due to variability in meteorology and climate change are expected to significantly impact atmospheric composition. The Mediterranean is a climate sensitive region and includes megacities like Istanbul and large urban agglomerations such as Athens. The effect of temperature changes on gaseous air pollutant levels and the atmospheric processes that are controlling them in the Eastern Mediterranean are here investigated. The WRF/CMAQ mesoscale modeling system is used, coupled with the MEGAN model for the processing of biogenic volatile organic compound emissions. A set of temperature perturbations (spanning from 1 to 5 K is applied on a base case simulation corresponding to July 2004. The results indicate that the Eastern Mediterranean basin acts as a reservoir of pollutants and their precursor emissions from large urban agglomerations. During summer, chemistry is a major sink at these urban areas near the surface, and a minor contributor at downwind areas. On average, the atmospheric processes are more effective within the first 1000 m above ground. Temperature increases lead to increases in biogenic emissions by 9±3% K−1. Ozone mixing ratios increase almost linearly with the increases in ambient temperatures by 1±0.1 ppb O3 K−1 for all studied urban and receptor stations except for Istanbul, where a 0.4±0.1 ppb O3 K−1 increase is calculated, which is about half of the domain-averaged increase of 0.9±0.1 ppb O3 K−1. The computed changes in atmospheric processes are also linearly related with temperature changes.

  19. Factors affecting the thermal environment of Agassiz’s Desert Tortoise (Gopherus agassizii) cover sites in the Central Mojave Desert during periods of temperature extremes

    Science.gov (United States)

    Mack, Jeremy S.; Berry, Kristin H.; Miller, David; Carlson, Andrea S.

    2015-01-01

    Agassiz's Desert Tortoises (Gopherus agassizii) spend >95% of their lives underground in cover sites that serve as thermal buffers from temperatures, which can fluctuate >40°C on a daily and seasonal basis. We monitored temperatures at 30 active tortoise cover sites within the Soda Mountains, San Bernardino County, California, from February 2004 to September 2006. Cover sites varied in type and structural characteristics, including opening height and width, soil cover depth over the opening, aspect, tunnel length, and surficial geology. We focused our analyses on periods of extreme temperature: in summer, between July 1 and September 1, and winter, between November 1 and February 15. With the use of multivariate regression tree analyses, we found cover-site temperatures were influenced largely by tunnel length and subsequently opening width and soil cover. Linear regression models further showed that increasing tunnel length increased temperature stability and dampened seasonal temperature extremes. Climate change models predict increased warming for southwestern North America. Cover sites that buffer temperature extremes and fluctuations will become increasingly important for survival of tortoises. In planning future translocation projects and conservation efforts, decision makers should consider habitats with terrain and underlying substrate that sustain cover sites with long tunnels and expanded openings for tortoises living under temperature extremes similar to those described here or as projected in the future.

  20. The role of land use change in the recent warming of daily extreme temperatures

    Science.gov (United States)

    Christidis, Nikolaos; Stott, Peter A.; Hegerl, Gabriele C.; Betts, Richard A.

    2013-02-01

    Abstract Understanding how temperature extremes respond in a climate forced by human activity is of great importance, as extreme temperatures are detrimental to health and often responsible for mortality increases. While previous detection and attribution studies demonstrated a significant human influence on the recent warming of daily extremes, contributions of individual anthropogenic forcings like changes in land use have not yet been investigated in such studies. Here we apply an optimal fingerprinting technique to data from observations and experiments with a new earth system model to examine whether changing land use has led to detectable changes in daily extreme temperatures on a quasi-global scale. We find that loss of trees and increase of grassland since preindustrial times has caused an overall cooling trend in both mean and extreme temperatures which is detectable in the observed changes of warm but not cold extremes. The warming in both mean and extreme temperatures due to anthropogenic forcings other than land use is detected in all cases, whereas the weaker effect of natural climatic forcings is not detected in any. This is the first formal attribution of observed climatic changes to changing land use, suggesting further investigations are justified, particularly in studies of warm extremes.

  1. Rising sea levels will reduce extreme temperature variations in tide-dominated reef habitats

    Science.gov (United States)

    Lowe, Ryan Joseph; Pivan, Xavier; Falter, James; Symonds, Graham; Gruber, Renee

    2016-01-01

    Temperatures within shallow reefs often differ substantially from those in the surrounding ocean; therefore, predicting future patterns of thermal stresses and bleaching at the scale of reefs depends on accurately predicting reef heat budgets. We present a new framework for quantifying how tidal and solar heating cycles interact with reef morphology to control diurnal temperature extremes within shallow, tidally forced reefs. Using data from northwestern Australia, we construct a heat budget model to investigate how frequency differences between the dominant lunar semidiurnal tide and diurnal solar cycle drive ~15-day modulations in diurnal temperature extremes. The model is extended to show how reefs with tidal amplitudes comparable to their depth, relative to mean sea level, tend to experience the largest temperature extremes globally. As a consequence, we reveal how even a modest sea level rise can substantially reduce temperature extremes within tide-dominated reefs, thereby partially offsetting the local effects of future ocean warming. PMID:27540589

  2. Daily temperature extremes play an important role in predicting thermal effects.

    Science.gov (United States)

    Ma, Gang; Hoffmann, Ary A; Ma, Chun-Sen

    2015-07-01

    Organisms in natural environments experience diel temperature fluctuations, including sporadic extreme conditions, rather than constant temperatures. Studies based mainly on model organisms have tended to focus on responses to average temperatures or short-term heat stress, which overlooks the potential impact of daily fluctuations, including stressful daytime periods and milder night-time periods. Here, we focus on daily maximum temperatures, while holding night-time temperatures constant, to specifically investigate the effects of high temperature on demographic parameters and fitness in the English grain aphid Sitobion avenae. We then compared the observed effects of different daily maximum temperatures with predictions from constant temperature-performance expectations. Moderate daily maximum temperatures depressed aphid performance while extreme conditions had dramatic effects, even when mean temperatures were below the critical maximum. Predictions based on daily average temperature underestimated negative effects of temperature on performance by ignoring daily maximum temperature, while predictions based on daytime maximum temperatures overestimated detrimental impacts by ignoring recovery under mild night-time temperatures. Our findings suggest that daily maximum temperature will play an important role in regulating natural population dynamics and should be considered in predictions. These findings have implications for natural population dynamics, particularly when considering the expected increase in extreme temperature events under climate change.

  3. The response of Arctic vegetation to the summer climate: relation between shrub cover, NDVI, surface albedo and temperature

    Energy Technology Data Exchange (ETDEWEB)

    Blok, Daan; Heijmans, Monique M P D; Berendse, Frank [Nature Conservation and Plant Ecology Group, Wageningen University, PO Box 47, 6700 AA, Wageningen (Netherlands); Schaepman-Strub, Gabriela [Institute of Evolutionary Biology and Environmental Studies, University of Zuerich, Winterthurerstrasse 190, 8057 Zuerich (Switzerland); Bartholomeus, Harm [Centre for Geo-Information, Wageningen University, PO Box 47, 6700 AA, Wageningen (Netherlands); Maximov, Trofim C, E-mail: daan.blok@wur.nl [Biological Problems of the Cryolithozone, Russian Academy of Sciences, Siberian Division, 41, Lenin Prospekt, Yakutsk, The Republic of Sakha, Yakutia 677980 (Russian Federation)

    2011-07-15

    Recently observed Arctic greening trends from normalized difference vegetation index (NDVI) data suggest that shrub growth is increasing in response to increasing summer temperature. An increase in shrub cover is expected to decrease summer albedo and thus positively feed back to climate warming. However, it is unknown how albedo and NDVI are affected by shrub cover and inter-annual variations in the summer climate. Here, we examine the relationship between deciduous shrub fractional cover, NDVI and albedo using field data collected at a tundra site in NE Siberia. Field data showed that NDVI increased and albedo decreased with increasing deciduous shrub cover. We then selected four Arctic tundra study areas and compiled annual growing season maximum NDVI and minimum albedo maps from MODIS satellite data (2000-10) and related these satellite products to tundra vegetation types (shrub, graminoid, barren and wetland tundra) and regional summer temperature. We observed that maximum NDVI was greatest in shrub tundra and that inter-annual variation was negatively related to summer minimum albedo but showed no consistent relationship with summer temperature. Shrub tundra showed higher albedo than wetland and barren tundra in all four study areas. These results suggest that a northwards shift of shrub tundra might not lead to a decrease in summer minimum albedo during the snow-free season when replacing wetland tundra. A fully integrative study is however needed to link results from satellite data with in situ observations across the Arctic to test the effect of increasing shrub cover on summer albedo in different tundra vegetation types.

  4. Contrasting responses of terrestrial ecosystem production to hot temperature extreme regimes between grassland and forest

    Directory of Open Access Journals (Sweden)

    Y. Zhang

    2014-04-01

    Full Text Available Observational data during the past several decades show faster increase of hot temperature extremes over land than changes in mean temperature. Towards more extreme temperature is expected to affect terrestrial ecosystem function. However, the ecological impacts of hot extremes on vegetation production remain uncertain across biomes in natural climatic conditions. In this study, we investigated the effects of hot temperature extremes on aboveground net primary production (ANPP by combining MODIS EVI dataset and in situ climatic records during 2000 to 2009 from 12 long-term experimental sites across biomes and climates. Our results showed that higher mean annual maximum temperatures (Tmax greatly reduced grassland production, and yet enhanced forest production after removing the effects of precipitation. Relative decreases in ANPP were 16% for arid grassland and 7% for mesic grassland, and the increase were 5% for forest. We also observed a significant positive relationship between interannual ANPP and Tmax for forest biome (R2 = 0.79, P < 0.001. This line of evidence suggests that hot temperature extreme leads to contrasting ecosystem-level response of vegetation production to warming climate between grassland and forest. Given that many terrestrial ecosystem models use average daily temperature as input, predictions of ecosystem production should consider these contrasting responses to more hot temperature extreme regimes associated with climate change.

  5. Extreme temperature sensing using brillouin scattering in optical fibers

    CERN Document Server

    Fellay, Alexandre

    Stimulated Brillouin scattering in silica-based optical fibers may be considered from two different and complementary standpoints. For a physicist, this interaction of light and pressure wave in a material, or equivalently in quantum theory terms between photons and phonons, gives some glimpses of the atomic structure of the solid and of its vibration modes. For an applied engineer, the same phenomenon may be put to good use as a sensing mechanism for distributed measurements, thanks to the dependence of the scattered light on external parameters such as the temperature, the pressure or the strain applied to the fiber. As far as temperature measurements are concerned, Brillouin-based distributed sensors have progressively gained wide recognition as efficient systems, even if their rather high cost still restricts the number of their applications. Yet they are generally used in a relatively narrow temperature range around the usual ambient temperature; in this domain, the frequency of the scattered light incre...

  6. Extreme Temperature, Rad-Hard Power Management ASIC Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Ridgetop Group will design a rad-hard Application Specific Integrated Circuit (ASIC) for spacecraft power management that is functional over a temperature range of...

  7. Electronic Modeling and Design for Extreme Temperatures Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to develop electronics for operation at temperatures that range from -230oC to +130oC. This new technology will minimize the requirements for external...

  8. Growth of group II Clostridium botulinum strains at extreme temperatures.

    Science.gov (United States)

    Derman, Yağmur; Lindström, Miia; Selby, Katja; Korkeala, Hannu

    2011-11-01

    The minimum and maximum growth temperatures and the maximum growth rates at 10, 30, 37, and 40°C were determined for 24 group II Clostridium botulinum strains. Genetic diversity of the strains was revealed by amplified fragment length polymorphism (AFLP) analysis. The minimum growth temperatures ranged from 6.2 to 8.6°C, and the maximum growth temperatures ranged from 34.7 to 39.9°C. The mean maximum growth temperatures and mean maximum growth rates of type E strains at 37°C were significantly higher than those of type B and type F strains. A significant correlation between maximum growth rates at 37°C and maximum growth temperatures was found for all strains. Some type E strains with a high minimum growth temperature also had a higher maximum growth rate at 37°C than at 30°C, which suggests that some group II C. botulinum strains are more mesophilic in their growth properties than others. We found relatively small differences between AFLP clusters, indicating that diverse genetic background among the strains was not reflected in the growth properties. The growth characteristics of group II C. botulinum and some type E strains with mesophilic growth properties may have an impact on inoculation studies and predictive modeling for assessing the safety of foods.

  9. Using soil moisture forecasts for sub-seasonal summer temperature predictions in Europe

    Science.gov (United States)

    Orth, René; Seneviratne, Sonia I.

    2014-12-01

    Soil moisture exhibits outstanding memory characteristics and plays a key role within the climate system. Especially through its impacts on the evapotranspiration of soils and plants, it may influence the land energy balance and therefore surface temperature. These attributes make soil moisture an important variable in the context of weather and climate forecasting. In this study we investigate the value of (initial) soil moisture information for sub-seasonal temperature forecasts. For this purpose we employ a simple water balance model to infer soil moisture from streamflow observations in 400 catchments across Europe. Running this model with forecasted atmospheric forcing, we derive soil moisture forecasts, which we then translate into temperature forecasts using simple linear relationships. The resulting temperature forecasts show skill beyond climatology up to 2 weeks in most of the considered catchments. Even if forecasting skills are rather small at longer lead times with significant skill only in some catchments at lead times of 3 and 4 weeks, this soil moisture-based approach shows local improvements compared to the monthly European Centre for Medium Range Weather Forecasting (ECMWF) temperature forecasts at these lead times. For both products (soil moisture-only forecast and ECMWF forecast), we find comparable or better forecast performance in the case of extreme events, especially at long lead times. Even though a product based on soil moisture information alone is not of practical relevance, our results indicate that soil moisture (memory) is a potentially valuable contributor to temperature forecast skill. Investigating the underlying soil moisture of the ECMWF forecasts we find good agreement with the simple model forecasts, especially at longer lead times. Analyzing the drivers of the temperature forecast skills we find that they are mainly controlled by the strengths of (1) the soil moisture-temperature coupling and (2) the soil moisture memory. We

  10. Seasonal predictability of sea surface temperature anomalies over the Kuroshio-Oyashio Extension: Low in summer and high in winter

    Science.gov (United States)

    Wu, Yujie; Duan, Wansuo; Rong, Xinyao

    2016-09-01

    The seasonal predictability of sea surface temperature anomalies (SSTA) in the Kuroshio-Oyashio Extension (KOE) is explored by performing perfect model predictability experiments from the viewpoint of initial error growth in a global coupled model. It is found that prediction errors of KOE-SSTA always increase in the boreal summer and decrease in the boreal winter. This leads to smaller (larger) prediction errors and higher (lower) prediction skills in boreal winter (summer). This seasonal characteristic of the KOE-SSTA error growth implies a season-dependent predictability that is lower in summer and higher in winter. The mechanism responsible for error growth associated with seasonal predictability is also explored. The error increase in summer and error decrease in winter in the KOE-SSTA are both largely attributed to the seasonal evolution of latent heat flux error and mean temperature advection by vertical current error in the KOE region, both of which are forced by the prediction error of 1 month leading zonal wind stress per unit mass for the mixed layer over the KOE region. The shallowest (deepest) mixed layer in summer (winter) amplifies (reduces) the forcing of zonal wind stress errors on the error growth of KOE-SSTA, thereby causing the seasonal evolution of prediction errors of KOE-SSTA and ultimately resulting in the season-dependent predictability of the KOE-SSTA, i.e., low in summer and high in winter.

  11. Variability and long-term change in Australian temperature and precipitation extremes

    Directory of Open Access Journals (Sweden)

    Dörte Jakob

    2016-12-01

    We conclude that in assessing the likelihood of climate hazards, one needs to consider the modulation of climate extremes due to both long-term change and climate variability. Our findings imply that when planning for adaptation, different emphasis needs to be given to changing temperature and precipitation extremes.

  12. Changing Temperature and Precipitation Extremes in Europe's Climate of the 20th Century

    NARCIS (Netherlands)

    Klein Tank, Albertus Maria Gerardus

    2004-01-01

    This thesis aims at increasing the knowledge on past changes in extremes through the analysis of historical records of observations at meteorological stations. The key question addressed is: How did the extremes of daily surface air temperature and precipitation change in Europe's climate of the

  13. Adaptation potential of naturally ventilated barns to high temperature extremes: The OptiBarn project

    Science.gov (United States)

    Menz, Christoph

    2016-04-01

    Climate change interferes with various aspects of the socio-economic system. One important aspect is its influence on animal husbandry, especially dairy faming. Dairy cows are usually kept in naturally ventilated barns (NVBs) which are particular vulnerable to extreme events due to their low adaptation capabilities. An effective adaptation to high outdoor temperatures for example, is only possible under certain wind and humidity conditions. High temperature extremes are expected to increase in number and strength under climate change. To assess the impact of this change on NVBs and dairy cows also the changes in wind and humidity needs to be considered. Hence we need to consider the multivariate structure of future temperature extremes. The OptiBarn project aims to develop sustainable adaptation strategies for dairy housings under climate change for Europe, by considering the multivariate structure of high temperature extremes. In a first step we identify various multivariate high temperature extremes for three core regions in Europe. With respect to dairy cows in NVBs we will focus on the wind and humidity field during high temperature events. In a second step we will use the CORDEX-EUR-11 ensemble to evaluate the capability of the RCMs to model such events and assess their future change potential. By transferring the outdoor conditions to indoor climate and animal wellbeing the results of this assessment can be used to develop technical, architectural and animal specific adaptation strategies for high temperature extremes.

  14. Extreme Temperatures May Increase Risk for Low Birth Weight at Term

    Science.gov (United States)

    ... at term, NIH study suggests Skip sharing on social media links Share this: Page Content Monday, February 27, 201 7 -Stock photo Extreme hot or cold temperatures during pregnancy may increase the risk that infants born at ...

  15. Summer temperature variability across four urban neighborhoods in Knoxville, Tennessee, USA

    Science.gov (United States)

    Ellis, Kelsey N.; Hathaway, Jon M.; Mason, Lisa Reyes; Howe, David A.; Epps, Thomas H.; Brown, Vincent M.

    2017-02-01

    The urban heat island (UHI) is a well-documented effect of urbanization on local climate, identified by higher temperatures compared to surrounding areas, especially at night and during the warm season. The details of a UHI are city-specific, and microclimates may even exist within a given city. Thus, investigating the spatiotemporal variability of a city's UHI is an ongoing and critical research need. We deploy ten weather stations across Knoxville, Tennessee, to analyze the city's UHI and its differential impacts across urban neighborhoods: two each in four neighborhoods, one in more dense tree cover and one in less dense tree cover, and one each in downtown Knoxville and Ijams Nature Center that serve as control locations. Three months of temperature data (beginning 2 July 2014) are analyzed using paired-sample t tests and a three-way analysis of variance. Major findings include the following: (1) Within a given neighborhood, tree cover helps negate daytime heat (resulting in up to 1.19 ∘C lower maximum temperature), but does not have as large of an influence on minimum temperature; (2) largest temperature differences between neighborhoods occur during the day (0.38-1.16 ∘C difference), but larger differences between neighborhoods and the downtown control occur at night (1.04-1.88 ∘C difference); (3) presiding weather (i.e., air mass type) has a significant, consistent impact on the temperature in a given city, and lacks the differential impacts found at a larger-scale in previous studies; (4) distance from city center does not impact temperature as much as land use factors. This is a preliminary step towards informing local planning with a scientific understanding of how mitigation strategies may help minimize the UHI and reduce the effects of extreme weather on public health and well-being.

  16. Summer water temperature of lowland Mazovian rivers in the context of fisheries management

    Directory of Open Access Journals (Sweden)

    Łaszewski Maksym

    2016-03-01

    Full Text Available Water temperatures in three upstream and three downstream profiles of the Jeziorka, Świder, and Utrata rivers were recorded in the summer period of hydrological year 2015 using digital data loggers. The measurement data was used to estimate statistical and ecological thermal parameters. The results demonstrated that water temperature in the studied lowland rivers was quite similar, except in the downstream reaches of the Utrata River, which is subjected to strong anthropogenic modification. The best thermal conditions for the survival and growth of the cold-water fish assemblage were observed upstream in the Jeziorka River in Głuchów, while the worst were downstream in the Utrata River in Nowy Łuszczewek. However, the results suggest that in quasi-natural rivers, such as the Jeziorka and Świder, cold-water fish can exist and be stocked in both the upstream and downstream segments. For the warm-water fish assemblage, the best thermal conditions were noted downstream in the Utrata River, while the worst were upstream in the Świder River; nevertheless, differences between the rivers were relatively small. The results of the analysis have practical implications for managing these waters with a view to optimizing angling and natural resources.

  17. [Effects of nitrogen fertilization, soil moisture and soil temperature on soil respiration during summer fallow season].

    Science.gov (United States)

    Zhang, Fang; Guo, Sheng-Li; Zou, Jun-Liang; Li, Ze; Zhang, Yan-Jun

    2011-11-01

    On the loess plateau, summer fallow season is a hot rainy time with intensive soil microbe activities. To evaluate the response of soil respiration to soil moisture, temperature, and N fertilization during this period is helpful for a deep understanding about the temporal and spatial variability of soil respiration and its impact factors, then a field experiment was conducted in the Changwu State Key Agro-Ecological Experimental Station, Shaanxi, China. The experiment included five N application rates: unfertilized 0 (N0), 45 (N45), 90 (N90), 135(N135), and 180 (N180) kg x hm(-2). The results showed that at the fallow stage, soil respiration rate significantly enhanced from 1.24 to 1.91 micromol x (m2 x s)(-1) and the average of soil respiration during this period [6.20 g x (m2 x d)(-1)] was close to the growing season [6.95 g x (m2 x d)(-1)]. The bivariate model of soil respiration with soil water and soil temperature was better than the single-variable model, but not so well as the three-factor model when explaining the actual changes of soil respiration. Nitrogen fertilization alone accounted for 8% of the variation soil respiration. Unlike the single-variable model, the results could provide crucial information for further research of multiple factors on soil respiration and its simulation.

  18. 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

    2017-02-01

    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.

  19. Solid Nitrogen at Extreme Conditions of High Pressure and Temperature

    Energy Technology Data Exchange (ETDEWEB)

    Goncharov, A; Gregoryanz, E

    2004-04-05

    We review the phase diagram of nitrogen in a wide pressure and temperature range. Recent optical and x-ray diffraction studies at pressures up to 300 GPa and temperatures in excess of 1000 K have provided a wealth of information on the transformation of molecular nitrogen to a nonmolecular (polymeric) semiconducting and two new molecular phases. These newly found phases have very large stability (metastability) range. Moreover, two new molecular phases have considerably different orientational order from the previously known phases. In the iota phase (unlike most of other known molecular phases), N{sub 2} molecules are orientationally equivalent. The nitrogen molecules in the theta phase might be associated into larger aggregates, which is in line with theoretical predictions on polyatomic nitrogen.

  20. Telemetry pill versus rectal and esophageal temperature during extreme rates of exercise-induced core temperature change

    NARCIS (Netherlands)

    Teunissen, L.P.J.; Haan, A. de; Koning, J.J. de; Daanen, H.A.M.

    2012-01-01

    Core temperature measurement with an ingestible telemetry pill has been scarcely investigated during extreme rates of temperature change, induced by short high-intensity exercise in the heat. Therefore, nine participants performed a protocol of rest, (sub)maximal cycling and recovery at 30 °C. The p

  1. Multiproxy summer and winter surface air temperature field reconstructions for southern South America covering the past centuries

    Energy Technology Data Exchange (ETDEWEB)

    Neukom, R.; Grosjean, M.; Wanner, H. [University of Bern, Oeschger Centre for Climate Change Research (OCCR), Bern (Switzerland); University of Bern, Institute of Geography, Climatology and Meteorology, Bern (Switzerland); Luterbacher, J. [Justus Liebig University of Giessen, Department of Geography, Climatology, Climate Dynamics and Climate Change, Giessen (Germany); Villalba, R.; Morales, M.; Srur, A. [CONICET, Instituto Argentino de Nivologia, Glaciologia y Ciencias Ambientales (IANIGLA), Mendoza (Argentina); Kuettel, M. [University of Bern, Oeschger Centre for Climate Change Research (OCCR), Bern (Switzerland); University of Bern, Institute of Geography, Climatology and Meteorology, Bern (Switzerland); University of Washington, Department of Earth and Space Sciences, Seattle (United States); Frank, D. [Swiss Federal Research Institute WSL, Birmensdorf (Switzerland); Jones, P.D. [University of East Anglia, Climatic Research Unit, School of Environmental Sciences, Norwich (United Kingdom); Aravena, J.-C. [Centro de Estudios Cuaternarios de Fuego Patagonia y Antartica (CEQUA), Punta Arenas (Chile); Black, D.E. [Stony Brook University, School of Marine and Atmospheric Sciences, Stony Brook (United States); Christie, D.A.; Urrutia, R. [Universidad Austral de Chile Valdivia, Laboratorio de Dendrocronologia, Facultad de Ciencias Forestales y Recursos Naturales, Valdivia (Chile); D' Arrigo, R. [Earth Institute at Columbia University, Tree-Ring Laboratory, Lamont-Doherty Earth Observatory, Palisades, NY (United States); Lara, A. [Universidad Austral de Chile Valdivia, Laboratorio de Dendrocronologia, Facultad de Ciencias Forestales y Recursos Naturales, Valdivia (Chile); Nucleo Cientifico Milenio FORECOS, Fundacion FORECOS, Valdivia (Chile); Soliz-Gamboa, C. [Utrecht Univ., Inst. of Environmental Biology, Utrecht (Netherlands); Gunten, L. von [Univ. of Bern (Switzerland); Univ. of Massachusetts, Climate System Research Center, Amherst (United States)

    2011-07-15

    We statistically reconstruct austral summer (winter) surface air temperature fields back to ad 900 (1706) using 22 (20) annually resolved predictors from natural and human archives from southern South America (SSA). This represents the first regional-scale climate field reconstruction for parts of the Southern Hemisphere at this high temporal resolution. We apply three different reconstruction techniques: multivariate principal component regression, composite plus scaling, and regularized expectation maximization. There is generally good agreement between the results of the three methods on interannual and decadal timescales. The field reconstructions allow us to describe differences and similarities in the temperature evolution of different sub-regions of SSA. The reconstructed SSA mean summer temperatures between 900 and 1350 are mostly above the 1901-1995 climatology. After 1350, we reconstruct a sharp transition to colder conditions, which last until approximately 1700. The summers in the eighteenth century are relatively warm with a subsequent cold relapse peaking around 1850. In the twentieth century, summer temperatures reach conditions similar to earlier warm periods. The winter temperatures in the eighteenth and nineteenth centuries were mostly below the twentieth century average. The uncertainties of our reconstructions are generally largest in the eastern lowlands of SSA, where the coverage with proxy data is poorest. Verifications with independent summer temperature proxies and instrumental measurements suggest that the interannual and multi-decadal variations of SSA temperatures are well captured by our reconstructions. This new dataset can be used for data/model comparison and data assimilation as well as for detection and attribution studies at sub-continental scales. (orig.)

  2. Observed Effects of Vegetation Growth on Temperature in the Early Summer over the Northeast China Plain

    Directory of Open Access Journals (Sweden)

    Xiaxiang Li

    2017-05-01

    Full Text Available The effect of vegetation on temperature is an emerging topic in the climate science community. Existing studies have mostly examined the effects of vegetation on daytime temperature (Tmax, whereas this study investigates the effects on nighttime temperature (Tmin. Ground measurements from 53 sites across northeastern China (NEC from 1982 to 2006 show that early summer (June Tmax and Tmin increased at mean rates of approximately 0.61 °C/10 year and 0.67 °C/10 year, respectively. Over the same period, the satellite-based Normalized Difference Vegetation Index (NDVI decreased by approximately 0.10 (accounting for 18% of the climatological NDVI for 1982–1991. It is highlighted that a larger increase in Tmax (Tmin co-occurred spatially with a larger (smaller decrease in NDVI. Deriving from such spatial co-occurrences, we found that the spatial variability of changes in Tmax (i.e., ΔTmax is negatively correlated with the spatial variability of changes in NDVI (i.e., ΔNDVI, while the spatial variability of changes in Tmin (i.e., ΔTmin is positively correlated (r2 = 0.10; p < 0.05 with that of ΔNDVI. Similarly, we detected significant positive correlations between the spatial variability of ΔNDVI and the change in surface latent heat flux (r2 = 0.16; p < 0.01 and in surface air specific humidity (r2 = 0.28; p < 0.001. These findings on the spatial co-occurrences suggest that the vegetation growth intensifies the atmospheric water vapor through evapotranspiration, which enhances the atmospheric downward longwave radiation and strengthens the greenhouse warming effects at night. Thereby, the positive correlation between ΔNDVI and ΔTmin is better understood. These results indicate that vegetation growth may not only exert effects on daytime temperature but also exert warming effects on nighttime temperature by increasing atmospheric water vapor and thus intensifying the local greenhouse effect. This study presents new observation evidence of the

  3. Circulation anomalies associated with winter temperature extremes in Athens during the period 1900-2004

    Energy Technology Data Exchange (ETDEWEB)

    Founda, D. [National Observatory of Athens (Greece). Inst. for Environmental Research and Sustainable Development; Loon, H. van [Colorado Univ., Boulder, CO (United States)

    2008-02-15

    We use the long series of temperature observed at the National Observatory of Athens, Greece, to examine the extremes of this element together with associated anomalies in the general circulation of the atmosphere. The 13 extreme-cold and 20 extreme-warm winters during the period 1900-2004 (equal to or below minus one standard deviation, and equal to or above plus one standard deviation respectively) had opposite pressure anomalies, mainly over the North Atlantic and Eurasia. The temperature extremes at Athens were representative of most of the Mediterranean and the Balkans, and their associated pressure anomalies were robust. The extremes of the Index of the North Atlantic Oscillation (the pressure difference between Gibraltar and Iceland) were not a good indicator of the temperature extremes in the Mediterranean. Rather the extreme temperature anomalies over the Mediterranean region are to a large extent controlled by a bipolar pattern of SLP (see level pressure) anomalies with centers over the British Isles and the Arctic. (orig.)

  4. 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℃.

  5. Observed features of temperature, salinity and current in central Chukchi Sea during the summer of 2012

    Institute of Scientific and Technical Information of China (English)

    HE Yan; LIU Na; CHEN Hongxia; TENG Fei; LIN Lina; WANG Huiwu

    2015-01-01

    During the summer of 2012, the fifth CHINARE Arctic Expedition was carried out, and a submersible mooring system was deployed in M5 station located at (69°30.155'N,169°00.654'W) and recovered 50d later. A set of temperature, salinity and current profile records was acquired. The characteristics of these observations are analyzed in this paper. Some main results are achieved as below. (1) Temperature generally decreases while salinity generally increases with increasing depth. The average values of all records are 2.98℃ and 32.21 psu. (2) Salinity and temperature are well negatively correlated, and the correlation coefficient between them is –0.84. However, they did not always vary synchronously. Their co-variation featured different characters during different significant periods. (3) The average velocity for the whole water column is 141 mm/s with directional angle of 347.1°. The statistical distribution curve of velocity record number gets narrower with increasing depth. More than 85% of the recorded velocities are northward, and the mean magnitudes of dominated northward velocities are 100–150 mm/s. (4) Rotary spectrum analysis shows that motions with low frequency take a majority of energy in all layers. The most significant energy peaks for all layers are around 0.012 cph (about 3.5 d period), while the tidal motion in mooring area is nonsignificant. (5) Velocities in all layers feature similar and synchronous temporal variations, except for the slight decrease in magnitude and leftward twist from top to bottom. The directions of velocity correspond well to those of surface wind. The average northward volume transport per square meter is 0.1–0.2 m3/s under southerly wind, but about –0.2 m3/s during northerly wind burst.

  6. 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.

  7. Long-Term Trends in Extreme Temperatures in Hong Kong and Southern China

    Institute of Scientific and Technical Information of China (English)

    T. C. LEE; H. S. CHAN; E. W. L. GINN; M. C. WONG

    2011-01-01

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

  8. Climate extremes in the Pacific: improving seasonal prediction of tropical cyclones and extreme ocean temperatures to improve resilience

    Science.gov (United States)

    Kuleshov, Y.; Jones, D.; Spillman, C. M.

    2012-04-01

    Climate change and climate extremes have a major impact on Australia and Pacific Island countries. Of particular concern are tropical cyclones and extreme ocean temperatures, the first being the most destructive events for terrestrial systems, while the latter has the potential to devastate ocean ecosystems through coral bleaching. As a practical response to climate change, under the Pacific-Australia Climate Change Science and Adaptation Planning program (PACCSAP), we are developing enhanced web-based information tools for providing seasonal forecasts for climatic extremes in the Western Pacific. Tropical cyclones are the most destructive weather systems that impact on coastal areas. Interannual variability in the intensity and distribution of tropical cyclones is large, and presently greater than any trends that are ascribable to climate change. In the warming environment, predicting tropical cyclone occurrence based on historical relationships, with predictors such as sea surface temperatures (SSTs) now frequently lying outside of the range of past variability meaning that it is not possible to find historical analogues for the seasonal conditions often faced by Pacific countries. Elevated SSTs are the primary trigger for mass coral bleaching events, which can lead to widespread damage and mortality on reef systems. Degraded coral reefs present many problems, including long-term loss of tourism and potential loss or degradation of fisheries. The monitoring and prediction of thermal stress events enables the support of a range of adaptive and management activities that could improve reef resilience to extreme conditions. Using the climate model POAMA (Predictive Ocean-Atmosphere Model for Australia), we aim to improve accuracy of seasonal forecasts of tropical cyclone activity and extreme SSTs for the regions of Western Pacific. Improved knowledge of extreme climatic events, with the assistance of tailored forecast tools, will help enhance the resilience and

  9. Qualification of Bonding Process of Temperature Sensors to Extreme Temperature Deep Space Missions

    Science.gov (United States)

    Ramesham, Rajeshuni; Kitiyakara, Amarit; Redick, Richard; Sunada, Eric T.

    2011-01-01

    A process has been explored based on the state-of-the-art technology to bond the platinum resistance thermometer (PRT) on to potential aerospace material such as a flat aluminum surface and a flexible copper tube to simulate coaxial cable for the flight applications. Primarily, PRTs were inserted into a metal plated copper braid to avoid stresses on the sensor while attaching the sensor with braid to the base material for long duration deep space missions. Appropriate pretreatment has been implemented in this study to enhance the adhesion of the PRTs to the base material. NuSil product has been chosen in this research to attach PRT to the base materials. The resistance (approx.1.1 k(Omega)) of PRTs has been electrically monitored continuously during the qualification thermal cycling testing from -150 C to +120 C and -100 C to -35 C. The test hardware has been thermal cycled three times the mission life per JPL design principles for JUNO project. No PRT failures were observed during and after the PRT thermal cycling qualification test for extreme temperature environments. However, there were some failures associated with staking of the PRT pig tails as a result of thermal cycling qualification test.

  10. Younger Dryas and Allerød summer temperatures at Gerzensee (Switzerland) inferred from fossil pollen and cladoceran assemblages

    NARCIS (Netherlands)

    Lotter, A.F.; Birks, H.J.B.; Eicher, U.; Hofmann, W.; Schwander, J.; Wick, L.

    2000-01-01

    Linear- and unimodal-based inference models for mean summer temperatures (partial least squares, weighted averaging, and weighted averaging partial least squares models) were applied to a high-resolution pollen and cladoceran stratigraphy from Gerzensee, Switzerland. The time-window of

  11. Effects of land cover change on temperature and rainfall extremes in multi-model ensemble simulations

    Directory of Open Access Journals (Sweden)

    A. J. Pitman

    2012-11-01

    Full Text Available The impact of historical land use induced land cover change (LULCC on regional-scale climate extremes is examined using four climate models within the Land Use and Climate, IDentification of robust impacts project. To assess those impacts, multiple indices based on daily maximum and minimum temperatures and daily precipitation were used. We contrast the impact of LULCC on extremes with the impact of an increase in atmospheric CO2 from 280 ppmv to 375 ppmv. In general, consistent changes in both high and low temperature extremes are similar to the simulated change in mean temperature caused by LULCC and are restricted to regions of intense modification. The impact of LULCC on both means and on most temperature extremes is statistically significant. While the magnitude of the LULCC-induced change in the extremes can be of similar magnitude to the response to the change in CO2, the impacts of LULCC are much more geographically isolated. For most models, the impacts of LULCC oppose the impact of the increase in CO2 except for one model where the CO2-caused changes in the extremes are amplified. While we find some evidence that individual models respond consistently to LULCC in the simulation of changes in rainfall and rainfall extremes, LULCC's role in affecting rainfall is much less clear and less commonly statistically significant, with the exception of a consistent impact over South East Asia. Since the simulated response of mean and extreme temperatures to LULCC is relatively large, we conclude that unless this forcing is included, we risk erroneous conclusions regarding the drivers of temperature changes over regions of intense LULCC.

  12. Technical Note: Bias correcting climate model simulated daily temperature extremes with quantile mapping

    Directory of Open Access Journals (Sweden)

    B. Thrasher

    2012-09-01

    Full Text Available When applying a quantile mapping-based bias correction to daily temperature extremes simulated by a global climate model (GCM, the transformed values of maximum and minimum temperatures are changed, and the diurnal temperature range (DTR can become physically unrealistic. While causes are not thoroughly explored, there is a strong relationship between GCM biases in snow albedo feedback during snowmelt and bias correction resulting in unrealistic DTR values. We propose a technique to bias correct DTR, based on comparing observations and GCM historic simulations, and combine that with either bias correcting daily maximum temperatures and calculating daily minimum temperatures or vice versa. By basing the bias correction on a base period of 1961–1980 and validating it during a test period of 1981–1999, we show that bias correcting DTR and maximum daily temperature can produce more accurate estimations of daily temperature extremes while avoiding the pathological cases of unrealistic DTR values.

  13. Assessment of indices of temperature extremes simulated by multiple CMIP5 models over China

    Science.gov (United States)

    Dong, Siyan; Xu, Ying; Zhou, Botao; Shi, Ying

    2015-08-01

    Given that climate extremes in China might have serious regional and global consequences, an increasing number of studies are examining temperature extremes in China using the Coupled Model Intercomparison Project Phase 5 (CMIP5) models. This paper investigates recent changes in temperature extremes in China using 25 state-of-the-art global climate models participating in CMIP5. Thirteen indices that represent extreme temperature events were chosen and derived by daily maximum and minimum temperatures, including those representing the intensity (absolute indices and threshold indices), duration (duration indices), and frequency (percentile indices) of extreme temperature. The overall performance of each model is summarized by a "portrait" diagram based on relative root-mean-square error, which is the RMSE relative to the median RMSE of all models, revealing the multi-model ensemble simulation to be better than individual model for most indices. Compared with observations, the models are able to capture the main features of the spatial distribution of extreme temperature during 1986-2005. Overall, the CMIP5 models are able to depict the observed indices well, and the spatial structure of the ensemble result is better for threshold indices than frequency indices. The spread amongst the CMIP5 models in different subregions for intensity indices is small and the median CMIP5 is close to observations; however, for the duration and frequency indices there can be wide disagreement regarding the change between models and observations in some regions. The model ensemble also performs well in reproducing the observational trend of temperature extremes. All absolute indices increase over China during 1961-2005.

  14. Creep strength of iridium at extremely high temperatures; Zeitstandfestigkeit von Iridium bei extrem hohen Temperaturen

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, B. [Fachhochschule Jena (Germany). Fachbereich Werkstofftechnik; Lupton, D. [Heraeus (W.C.) GmbH, Hanau (Germany). Produktbereich Materialtechnik; Braun, F. [Heraeus (W.C.) GmbH, Hanau (Germany). Produktbereich Materialtechnik; Merker, J. [Jena Univ. (Germany). Technisches Inst.; Helmich, R. [Jena Univ. (Germany). Technisches Inst.

    1994-12-31

    On iridium in the initial state and after carrying out creep tests, apart from metallographic and fractographic work, investigations on the distribution of trace impurities were done by means of secondary ion mass spectroscopy and investigations of the crystal structure were carried out with the aid of Kossel technique, a special field of X-ray bending. Although iridium of high purity was used for the investigations, enrichment of hydrogen, carbon, sodium, potassium, calcium, magnesium, silicon, iron, nickel and chromium was proved by means of secondary ion mass spectroscopy at the grain boundaries, where the average contents in iridium were only about 1 {mu}g/g. In the creep test, creep fracture lines were found in the range of 1800 to 2300 C and about 0.5 to 12 hours on iridium samples with a square cross section of 1 mm. It follows from the results that this noble metal has a considerable resistance to heat at these temperatures, which makes its use up to 2300 C possible. (orig./RHM) [Deutsch] Es erfolgten am Iridium im Ausgangszustand und nach Durchfuehrung der Zeitstandversuche neben metallographischen und fraktographischen Arbeiten Untersuchungen zur Verteilung der Spurenverunreinigungen mittels Sekundaerionen-Massenspektroskopie sowie Untersuchungen der Kristallstruktur mit Hilfe der Kossel-Technik, einem Spezialgebiet der Roentgenbeugung. Obwohl fuer die Untersuchungen hochreines Iridium verwendet wurde, konnten mittels Sekundaerionen-Massenspektroskopie in den Korngrenzen Anreicherungen von Wasserstoff, Kohlenstoff, Natrium, Kalium, Calcium, Magnesium, Silizium, Eisen, Nickel und Chrom nachgewiesen werden, wobei die durchschnittlichen Gehalte in Iridium nur um 1 {mu}g/g lagen. Im Zeitstandversuch wurden an Iridiumproben mit 1 mm Vierkantquerschnitt Zeitbruchlinien im Bereich von 1800 bis 2300 C und etwa 0,5 bis 12 Stunden aufgenommen. Aus den Ergebnissen folgt, dass das Edelmetall bei diesen Temperaturen noch eine beachtliche Warmfestigkeit besitzt, die

  15. Leaf anatomical and photosynthetic acclimation to cool temperature and high light in two winter versus two summer annuals.

    Science.gov (United States)

    Cohu, Christopher M; Muller, Onno; Adams, William W; Demmig-Adams, Barbara

    2014-09-01

    Acclimation of foliar features to cool temperature and high light was characterized in winter (Spinacia oleracea L. cv. Giant Nobel; Arabidopsis thaliana (L.) Heynhold Col-0 and ecotypes from Sweden and Italy) versus summer (Helianthus annuus L. cv. Soraya; Cucurbita pepo L. cv. Italian Zucchini Romanesco) annuals. Significant relationships existed among leaf dry mass per area, photosynthesis, leaf thickness and palisade mesophyll thickness. While the acclimatory response of the summer annuals to cool temperature and/or high light levels was limited, the winter annuals increased the number of palisade cell layers, ranging from two layers under moderate light and warm temperature to between four and five layers under cool temperature and high light. A significant relationship was also found between palisade tissue thickness and either cross-sectional area or number of phloem cells (each normalized by vein density) in minor veins among all four species and growth regimes. The two winter annuals, but not the summer annuals, thus exhibited acclimatory adjustments of minor vein phloem to cool temperature and/or high light, with more numerous and larger phloem cells and a higher maximal photosynthesis rate. The upregulation of photosynthesis in winter annuals in response to low growth temperature may thus depend on not only (1) a greater volume of photosynthesizing palisade tissue but also (2) leaf veins containing additional phloem cells and presumably capable of exporting a greater volume of sugars from the leaves to the rest of the plant.

  16. Verification of surface minimum, mean, and maximum temperature forecasts in Calabria for summer 2008

    Directory of Open Access Journals (Sweden)

    S. Federico

    2011-02-01

    Full Text Available Since 2005, one-hour temperature forecasts for the Calabria region (southern Italy, modelled by the Regional Atmospheric Modeling System (RAMS, have been issued by CRATI/ISAC-CNR (Consortium for Research and Application of Innovative Technologies/Institute for Atmospheric and Climate Sciences of the National Research Council and are available online at http://meteo.crati.it/previsioni.html (every six hours. Beginning in June 2008, the horizontal resolution was enhanced to 2.5 km. In the present paper, forecast skill and accuracy are evaluated out to four days for the 2008 summer season (from 6 June to 30 September, 112 runs. For this purpose, gridded high horizontal resolution forecasts of minimum, mean, and maximum temperatures are evaluated against gridded analyses at the same horizontal resolution (2.5 km.

    Gridded analysis is based on Optimal Interpolation (OI and uses the RAMS first-day temperature forecast as the background field. Observations from 87 thermometers are used in the analysis system. The analysis error is introduced to quantify the effect of using the RAMS first-day forecast as the background field in the OI analyses and to define the forecast error unambiguously, while spatial interpolation (SI analysis is considered to quantify the statistics' sensitivity to the verifying analysis and to show the quality of the OI analyses for different background fields.

    Two case studies, the first one with a low (less than the 10th percentile root mean square error (RMSE in the OI analysis, the second with the largest RMSE of the whole period in the OI analysis, are discussed to show the forecast performance under two different conditions. Cumulative statistics are used to quantify forecast errors out to four days. Results show that maximum temperature has the largest RMSE, while minimum and mean temperature errors are similar. For the period considered

  17. Resilience of coral calcification to extreme temperature variations in the Kimberley region, northwest Australia

    Science.gov (United States)

    Dandan, S. S.; Falter, J. L.; Lowe, R. J.; McCulloch, M. T.

    2015-12-01

    We report seasonal changes in coral calcification within the highly dynamic intertidal and subtidal zones of Cygnet Bay (16.5°S, 123.0°E) in the Kimberley region of northwest Australia, where the tidal range can reach nearly 8 m and the temperature of nearshore waters ranges seasonally by ~9 °C from a minimum monthly mean of ~22 °C to a maximum of over 31 °C. Corals growing within the more isolated intertidal sites experienced maximum temperatures of up to ~35 °C during spring low tides in addition to being routinely subjected to high levels of irradiance (>1500 µmol m-2 s-1) under near stagnant conditions. Mixed model analysis revealed a significant effect of tidal exposure on the growth of Acropora aspera, Dipsastraea favus, and Trachyphyllia geoffroyi ( p ≤ 0.04), as well as a significant effect of season on A. aspera and T. geoffroyi ( p ≤ 0.01, no effect on D. favus); however, the growth of both D. favus and T. geoffroyi appeared to be better suited to the warm summer conditions of the intertidal compared to A. aspera. Through an additional comparative study, we found that Acropora from Cygnet Bay calcified at a rate 69 % faster than a species from the same genus living in a backreef environment of a more typical tropical reef located 1200 km southwest of Cygnet Bay (0.59 ± 0.02 vs. 0.34 ± 0.02 g cm-2 yr-1 for A. muricata from Coral Bay, Ningaloo Reef; p < 0.001, df = 28.9). The opposite behaviour was found for D. favus from the same environments, with colonies from Cygnet Bay calcifying at rates that were 33 % slower than the same species from Ningaloo Reef (0.29 ± 0.02 vs. 0.44 ± 0.03 g cm-2 yr-1, p < 0.001, df = 37.9). Our findings suggest that adaption and/or acclimatization of coral to the more thermally extreme environments at Cygnet Bay is strongly taxon dependent.

  18. Investigating the impact of land-use land-cover change on Indian summer monsoon daily rainfall and temperature during 1951–2005 using a regional climate model

    Directory of Open Access Journals (Sweden)

    S. Halder

    2015-07-01

    Full Text Available Daily moderate rainfall events, that constitute a major portion of seasonal summer monsoon rainfall over central India, have decreased significantly during the period 1951 till 2005. Mean and extreme near surface daily temperature during the monsoon season have also increased by a maximum of 1–1.5 °C. Using simulations made with a high-resolution regional climate model (RegCM4 with prescribed vegetation cover of 1950 and 2005, it is demonstrated that part of the above observed changes in moderate rainfall events and temperature have been caused by land-use land-cover change (LULCC which is mostly anthropogenic. Model simulations show that the increase in seasonal mean and extreme temperature over central India coincides with the region of decreased (increased forest (crop cover. The results also show that land-use land-cover alone causes warming in the extremes of daily mean and maximum temperatures by maximum of 1–1.2 °C, that is comparable with the observed increasing trend in the extremes. Decrease (increase in forest (crop cover reduces the evapotranspiration over land and large-scale convective instability, apart from decreasing the moisture convergence. These factors act together not only in reducing the moderate rainfall events over central India but also the amount of rainfall in that category, significantly. This is the most interesting result of this study. Additionally, the model simulations are repeated by removing the warming trend in sea surface temperatures. As a result, there is enhanced warming at the surface and decrease in moderate rainfall events over central India. Results from the additional experiments corroborate our initial findings and confirm the contribution of land-use land-cover change on increase in daily mean and extreme temperature and decrease in moderate rainfall events. This study not only demonstrates the important implications of LULCC over India, but also shows the necessity for inclusion of projected

  19. Assessment of climate variations in temperature and precipitation extreme events over Iran

    Science.gov (United States)

    Soltani, M.; Laux, P.; Kunstmann, H.; Stan, K.; Sohrabi, M. M.; Molanejad, M.; Sabziparvar, A. A.; Ranjbar SaadatAbadi, A.; Ranjbar, F.; Rousta, I.; Zawar-Reza, P.; Khoshakhlagh, F.; Soltanzadeh, I.; Babu, C. A.; Azizi, G. H.; Martin, M. V.

    2016-11-01

    In this study, changes in the spatial and temporal patterns of climate extreme indices were analyzed. Daily maximum and minimum air temperature, precipitation, and their association with climate change were used as the basis for tracking changes at 50 meteorological stations in Iran over the period 1975-2010. Sixteen indices of extreme temperature and 11 indices of extreme precipitation, which have been quality controlled and tested for homogeneity and missing data, are examined. Temperature extremes show a warming trend, with a large proportion of stations having statistically significant trends for all temperature indices. Over the last 15 years (1995-2010), the annual frequency of warm days and nights has increased by 12 and 14 days/decade, respectively. The number of cold days and nights has decreased by 4 and 3 days/decade, respectively. The annual mean maximum and minimum temperatures averaged across Iran both increased by 0.031 and 0.059 °C/decade. The probability of cold nights has gradually decreased from more than 20 % in 1975-1986 to less than 15 % in 1999-2010, whereas the mean frequency of warm days has increased abruptly between the first 12-year period (1975-1986) and the recent 12-year period (1999-2010) from 18 to 40 %, respectively. There are no systematic regional trends over the study period in total precipitation or in the frequency and duration of extreme precipitation events. Statistically significant trends in extreme precipitation events are observed at less than 15 % of all weather stations, with no spatially coherent pattern of change, whereas statistically significant changes in extreme temperature events have occurred at more than 85 % of all weather stations, forming strongly coherent spatial patterns.

  20. Rooting depth, water relations and non-structural carbohydrate dynamics in three woody angiosperms differentially affected by an extreme summer drought.

    Science.gov (United States)

    Nardini, Andrea; Casolo, Valentino; Dal Borgo, Anna; Savi, Tadeja; Stenni, Barbara; Bertoncin, Paolo; Zini, Luca; McDowell, Nathan G

    2016-03-01

    In 2012, an extreme summer drought induced species-specific die-back in woody species in Northeastern Italy. Quercus pubescens and Ostrya carpinifolia were heavily impacted, while Prunus mahaleb was largely unaffected. By comparing seasonal changes in isotopic composition of xylem sap, rainfall and deep soil samples, we show that P. mahaleb has a deeper root system than the other two species. This morphological trait allowed P  mahaleb to maintain higher water potential (Ψ), gas exchange rates and non-structural carbohydrates content (NSC) throughout the summer, when compared with the other species. More favourable water and carbon states allowed relatively stable maintenance of stem hydraulic conductivity (k) throughout the growing season. In contrast, in Quercus pubescens and Ostrya carpinifolia, decreasing Ψ and NSC were associated with significant hydraulic failure, with spring-to-summer k loss averaging 60%. Our data support the hypothesis that drought-induced tree decline is a complex phenomenon that cannot be modelled on the basis of single predictors of tree status like hydraulic efficiency, vulnerability and carbohydrate content. Our data highlight the role of rooting depth in seasonal progression of water status, gas exchange and NSC, with possible consequences for energy-demanding mechanisms involved in the maintenance of vascular integrity. © 2015 John Wiley & Sons Ltd.

  1. Polar summer mesospheric extreme horizontal drift speeds during interplanetary corotating interaction regions (CIRs) and high-speed solar wind streams: Coupling between the solar wind and the mesosphere

    Science.gov (United States)

    Lee, Young-Sook; Kirkwood, Sheila; Kwak, Young-Sil; Kim, Kyung-Chan; Shepherd, Gordon G.

    2014-05-01

    We report the observation of echo extreme horizontal drift speed (EEHS, ≥ 300 m s-1) during polar mesospheric (80-90 km) summer echoes (PMSEs) by the VHF (52 MHz) radar at Esrange, Sweden, in years of 2006 and 2008. The EEHS occur in PMSEs as correlated with high-speed solar wind streams (HSSs), observed at least once in 12-17% of all hours of observation for the two summers. The EEHS rate peaks occur either during high solar wind speed in the early part of the PMSE season or during the arrival of interplanetary corotating interaction regions (CIRs) followed by peaks in PMSE occurrence rate after 1-4 days, in the latter part of the 2006 summer. The cause of EEHS rate peaks is likely under the competition between the interval of the CIR and HSS passage over the magnetosphere. A candidate process in producing EEHS is suggested to be localized strong electric field, which is caused by solar wind energy transfer from the interaction of CIR and HSS with the magnetosphere in a sequential manner. We suggest that EEHS are created by strong electric field, estimated as > 10-30 V m-1 at 85 km altitude, exceeding the mesospheric breakdown threshold field.

  2. Trends of Summer Air Temperatures in the Romanian Carpathians Detected by Using a Serially Correlated Errors Model

    Directory of Open Access Journals (Sweden)

    Adina-Eliza CROITORU

    2014-11-01

    Full Text Available This paper investigates summer temperature trends in the Romanian Carpathian Mountains, for three types of topographies: summit, slope and depression. We used a change-point regression model with serially correlated errors and compared it with a mainstream change-point model with independent errors. Statistical theory ensures that the former model gives a more accurate trend analysis than the latter model. For both models we identified strongly decreasing trends before the change-point and strongly increasing trends afterwards for most summer temperature series. The change-points are more consistent with each other, in the early 80’s, when using the former model. These general results occur for all topography types. A separate multiple regression model reveals that the temperature dynamics in the Romanian Carpathians can be explained by a linear effect of several major atmospheric circulation patterns

  3. Precipitation and temperatures extremes in East Africa in past and future climate

    OpenAIRE

    Kuya, Elinah Khasandi

    2016-01-01

    Climate change has increased extreme weather events over the planet. The most robust changes in East Africa (EA) are for daily temperature and precipitation, where high-impact extreme values have become more common. The overall magnitude, seasonal distribution of precipitation and its inter-annual variability have been altered. East Africa experiences some of the most severe convective storms in the world. They can come without warning and are becoming more frequent. These changes present sig...

  4. Mitigation of effects of extreme drought during stage III of peach fruit development by summer pruning and fruit thinning.

    Science.gov (United States)

    Lopez, Gerardo; Mata, Mercè; Arbones, Amadeu; Solans, Josep R; Girona, Joan; Marsal, Jordi

    2006-04-01

    A water deficit during stage III of fruit growth was established with the aim of determining if it is possible to achieve an improvement in tree water status by summer pruning and fruit thinning. The experiment was set up as a randomized block split-plot design across trials (irrigation) where pruning was assigned to the main plot and fruit thinning to the sub-plots. The irrigation treatments were (1) standard full irrigation (FI), and (2) suppression of irrigation during stage III of fruit growth until leaves visibly withered (LWI); the pruning treatments were (1) experimental summer pruning (EP), and (2) standard summer pruning (CP); and three fruit thinning intensities were applied to facilitate analysis of the effects of the treatments in relation to fruit load. Changes in amount of light intercepted and in tree stem water potential (Psi stem) were evaluated. The EP treatment reduced the amount of light intercepted by the tree. In the FI treatment, there was a significant reduction in fruit growth measured as both water accumulation and dry mass accumulation. Under FI conditions, reductions in fruit load as a result of EP were not accompanied by a significant improvement in Psi stem. In the LWI treatment, EP produced a significant improvement of 0.17 MPa in Psi stem, but there was no improvement in fruit growth compared with CP trees. A reduction in fruit load from 350 (commercial load) to 150 per tree significantly improved Psi stem by 0.3 MPa at the end of stage III of fruit growth. These results indicate that improvements in water status in response to pruning may be insufficient to promote fruit growth if the pruned trees are unable to provide an adequate supply of assimilates to the developing fruits.

  5. Changes in magnitude and frequency of heavy precipitation across China and its potential links to summer temperature

    Science.gov (United States)

    Gu, Xihui; Zhang, Qiang; Singh, Vijay P.; Shi, Peijun

    2017-04-01

    Changes in the magnitude, frequency and timing of heavy precipitation are closely related to the occurrence of floods and droughts, which hold a great deal of significance for management of agricultural irrigation and water resources. Records of daily precipitation and temperature from 728 stations across China were used to assess changes in the magnitude, frequency and timing of heavy precipitation using the Peak-over-Threshold (POT) with 95th percentile as the threshold. Because of the continuous nature of the magnitude and timing of heavy precipitation, the ;change point; method and the modified Mann-Kendall trend test method were used to detect change points (CPs) and slowly-varying changes, respectively. In addition, the segmented regression and Poisson regression methods were used to detect CPs and temporal trends in the frequency of heavy precipitation, respectively, with consideration of the count nature of the data. The results showed that 55% and 36% of the stations had CPs in mean and/or variance of the magnitude and timing, respectively, while the percentage is only 5.8% in the frequency. However, while there is limited evidence of significant trends in the magnitude and timing, strong evidence points to a significant increasing frequency in most regions of China. These changes may be partly explained by changes in summer temperature. Examination of the summer surface temperature records suggests that the areas, where the frequency of heavy precipitation has a significant increase, are also mostly characterized by significant increasing temperature. In addition, trends of the frequency vary between the periods before and after the turn point (TP) of summer temperature trends, especially in northern China where both the summer temperature and the frequency have shifted significantly decreasing trends to significantly increasing trends. A possible interpretation of these findings is that storms tend to be more frequent without significant changes in water

  6. Coldest Temperature Extreme Monotonically Increased and Hottest Extreme Oscillated over Northern Hemisphere Land during Last 114 Years

    Science.gov (United States)

    Zhou, Chunlüe; Wang, Kaicun

    2016-05-01

    Most studies on global warming rely on global mean surface temperature, whose change is jointly determined by anthropogenic greenhouse gases (GHGs) and natural variability. This introduces a heated debate on whether there is a recent warming hiatus and what caused the hiatus. Here, we presented a novel method and applied it to a 5° × 5° grid of Northern Hemisphere land for the period 1900 to 2013. Our results show that the coldest 5% of minimum temperature anomalies (the coldest deviation) have increased monotonically by 0.22 °C/decade, which reflects well the elevated anthropogenic GHG effect. The warmest 5% of maximum temperature anomalies (the warmest deviation), however, display a significant oscillation following the Atlantic Multidecadal Oscillation (AMO), with a warming rate of 0.07 °C/decade from 1900 to 2013. The warmest (0.34 °C/decade) and coldest deviations (0.25 °C/decade) increased at much higher rates over the most recent decade than last century mean values, indicating the hiatus should not be interpreted as a general slowing of climate change. The significant oscillation of the warmest deviation provides an extension of previous study reporting no pause in the hottest temperature extremes since 1979, and first uncovers its increase from 1900 to 1939 and decrease from 1940 to 1969.

  7. Relationship between extreme Precipitation and Temperature over Japan: An analysis from Multi-GCMs and Multi-RCMs products

    Science.gov (United States)

    Nayak, S.; Dairaku, K.; Takayabu, I.

    2014-12-01

    According to the IPCC reports, the concentration of CO­2 has been increasing and projected to be increased significantly in future (IPCC, 2012). This can have significant impacts on climate. For instance, Dairaku and Emori (2006) examined over south Asia by doubling CO2 and documented an increase in precipitation intensities during Indian summer monsoon. This would increase natural disasters such as floods, landslide, coastal disaster, erosion etc. Recent studies investigated whether the rate of increase of extreme precipitation is related with the rate expected by Clausius-Clapeyron (CC) relationship (approximately 7% per degree temperature rise). In our study, we examine whether this rate can increase or decrease in the future regional climate scenarios over Japan. We have analysed the ensemble experiments by three RCMs(NHRCM, NRAMS, WRF) forced by JRA25 as well as three GCMs (CCSM4, MIROC5, MRI-GCM3) for the current climate (1981-2000) and future scenario (2081-2100, RCP4.5) over Japan. We have stratified the extreme (99th, 95th, 90th, 75th percentile) precipitation of daily sum and daily maximum of hourly precipitation intensities of wet events based on daily mean temperature in bins of 1°C width for annual as well as for each season (DJF, MAM, JJA, SON). The results indicate that precipitation intensity increases when temperature increases roughly up to 22 °C and further increase of temperature decreases the precipitation intensities. The obtained results are consistent and match with the observation (APHRODITE dataset) over Japan. The decrease of precipitation at higher temperature mainly can be found in JJA. It is also noticed that the rate of specific humidity is estimated higher during JJA than other seasons. The rate of increase of extreme precipitation is similar to the rate expected by CC relation except DJF (nearly twice of CC relation) in current climate. This rate becomes to be significantly larger in future scenario for higher temperatures than

  8. Investigation of the impact of extreme air temperature on river water temperature: case study of the heat episode 2013.

    Science.gov (United States)

    Weihs, Philipp; Trimmel, Heidelinde; Goler, Robert; Formayer, Herbert; Holzapfel, Gerda; Rauch, Hans Peter

    2014-05-01

    Water stream temperature is a relevant factor for water quality since it is an important driver of water oxygen content and in turn also reduces or increases stress on the aquatic fauna. The water temperature of streams is determined by the source and inflow water temperature, by the energy balance at the stream surface and by the hydrological regime of the stream. Main factors driving the energy balance of streams are radiation balance and air temperature which influences the sensitive and latent heat flux. The present study investigates the impact of the heat episode of summer 2013 on water temperature of two lowland rivers in south eastern Austria. Within the scope of the project BIO_CLIC routine measurements of water temperature at 33 locations alongside the rivers Pinka and Lafnitz have been performed since spring 2012. In addition meteorological measurements of global shortwave and longwave radiation, air temperature, wind and air humidity have been carried out during this time. For the same time period, data of discharge and water levels of both rivers were provided by the public hydrological office. The heat episode of summer 2013 started, according to the Kysely- definition, on 18 July and lasted until 14 August. The highest air temperature ever recorded in Austria was reported on 8 August at 40.5°C. In Güssing, which is located within the project area, 40.0 °C were recorded. In the lower reaches of the river Pinka, at the station Burg the monthly mean water temperature of August 2013 was with more than 22°C, 1°C higher than the mean water temperature of the same period of the previous years. At the same station, the maximum water temperature of 27.1°C was recorded on 29 July, 9 days prior to the air temperature record. Analysis shows that at the downstream stations the main driving parameter is solar radiation whereas at the upstream stations a better correlation between air temperature and water temperature is obtained. Using the extensive data set

  9. 近50年来祁连山及河西走廊极端气温的季节变化特征%Seasonal Characteristics of Extreme Temperature Changes in Qilian Mountains and Hexi Corridor During Last Fifty Years

    Institute of Scientific and Technical Information of China (English)

    贾文雄

    2012-01-01

    Based on daily temperature data of 18 meteorological stations in Qilian Mountains and Hexi Corri- dor from 1960 to 2009, the seasonal characteristics of extreme temperature change were analyzed by methods of linear trend, Morlet wavelet and Mann-Kendall. The results indicate that extreme high temperature days in each season are on the rise significantly, especially increased with larger scales after the middle of 1980s. But that is contrary to extreme low temperature days, which decreased with larger scales after the middle of 1980s in spring and summer, and decreased after the middle and later of 1960s in autumn and winter. The changing scale of extreme temperature days is the largest in winter, and the changes of them are before ten years in win- ter than in other seasons, which indicated that the significant change of extreme temperature days took place in winter firstly. The cycle changes of extreme temperature days in different seasons are different, but they are grouped in 6-10 a, 12-16 a and 18-22 a. The major cycle of extreme high temperature days in spring, summer, autumn and winter are changing respectivelywith 8 a, 14 a, 16 a and 16 a, and that of extreme low temperature days are changing respectively with 14 a, 16 a, 14 a and 6 a. The mutation of extreme high temperature days in spring, summer, autumn and winter increased in 2002, 1997, 1994, 1986, respectively, but that of extreme low temperature days decreased in 2002, 1997, 1987, 1986, respectively. Except autumn, the abrupt changes of ex- treme high temperature days and extreme low temperature days in other seasons are coincident. The response to global warming of extreme temperature days is earlier in autumn and winter than that in spring and summer. The change of extreme temperature days will bring some effect to the Qilian Mountains and Hexi Corridor. The increase of extreme high temperature days will add pressure of preventing fire for forest and grasslands in Qilian Mountains. The decrease of

  10. Impact of temperature and precipitation extremes on the flowering dates of four German wildlife shrub species

    Science.gov (United States)

    Siegmund, Jonatan F.; Wiedermann, Marc; Donges, Jonathan F.; Donner, Reik V.

    2016-10-01

    Ongoing climate change is known to cause an increase in the frequency and amplitude of local temperature and precipitation extremes in many regions of the Earth. While gradual changes in the climatological conditions have already been shown to strongly influence plant flowering dates, the question arises if and how extremes specifically impact the timing of this important phenological phase. Studying this question calls for the application of statistical methods that are tailored to the specific properties of event time series. Here, we employ event coincidence analysis, a novel statistical tool that allows assessing whether or not two types of events exhibit similar sequences of occurrences in order to systematically quantify simultaneities between meteorological extremes and the timing of the flowering of four shrub species across Germany. Our study confirms previous findings of experimental studies by highlighting the impact of early spring temperatures on the flowering of the investigated plants. However, previous studies solely based on correlation analysis do not allow deriving explicit estimates of the strength of such interdependencies without further assumptions, a gap that is closed by our analysis. In addition to direct impacts of extremely warm and cold spring temperatures, our analysis reveals statistically significant indications of an influence of temperature extremes in the autumn preceding the flowering.

  11. 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.

  12. A Study on Extremely Dry and Wet Summer Monsoon in Pakistan by Focusing on the Anomalous States of the Upper Troposphere

    Science.gov (United States)

    Ahmad, S.; Koike, T.; Nishii, K.

    2012-04-01

    Seasonally-changes in wind pattern, monsoon, sometimes results in severe droughts and intense flooding in many parts of the world including South Asian countries like Pakistan. The livelihood of a vast population in Pakistan depends on agriculture and land use is strongly influenced by water-based ecosystems that depend on the monsoon rains. Furthermore, climate change studies undertaken so far reveal that action is essential in order to prevent long term damage to water cycle and thus of great concern to the community and stakeholders. Pakistan Summer Monsoon (PSM) is generally affected by both the disturbances from the tropical and the extratropical regions; however there is lack of understanding of physical mechanisms of PSM compared to other regional studies i.e. Indian Summer Monsoon (ISM) and South-East Asian Monsoon (SEAM). In our study, we applied heat and vorticity budgets and wave train analysis to reveal the mechanisms of the extremely dry and wet PSM events associated with the anomalous upper tropospheric circulation. We found that the extremely dry (wet) PSM events are closely related with the strengthening(weakening) of the upper-tropospheric central Asian high. We also found that in addition to Rossby-wave (Matsuno-Gill) type atmospheric response, the Rossby wave train along the Asian Jet originating from northwestern Europe or North Atlantic Ocean strengthened(weakened) the upper-tropospheric central Asian high. Therefore strong convection anomalies resulting in severe flooding (drought) events over the PSM region are induced by both the tropical and extratropical processes. Key Words: Pakistan, Extremes Monsoon Events, Physical Processes, Heat Budget, Vorticity, Wave Train

  13. Attribution analyses of temperature extremes using a set of 16 indices

    Directory of Open Access Journals (Sweden)

    Nikolaos Christidis

    2016-12-01

    Full Text Available Detection and attribution studies have demonstrated that anthropogenic forcings have been driving significant changes in temperature extremes since the middle of the 20th century. Moreover, new methodologies have been developed for the attribution of extreme events that assess how human influence may have changed their characteristics. Here we combine formal statistical analyses based on optimal fingerprinting to attribute observed long term changes in temperature extremes with an ensemble-based approach for event attribution. Our analyses are applied to 16 indices constructed with daily temperature data that focus on different characteristics of extremes and together build up a more complete representation of historical changes in warm and cold extremes than previous studies. For each index we compute an annual value for all years of the post-1960 period using data from observations and experiments with a coupled Earth System model for the analysis of multi-decadal changes and a high-resolution atmospheric model for event attribution. The models indicate that anthropogenic forcings have influenced almost all indices in recent decades and led to more prominent changes in the frequency of extremes. The optimal fingerprinting analyses show that for most indices the anthropogenic signal is detectable in changes during 1961–2010 both in Europe and on a quasi-global scale. The weaker natural effect, resulting mainly from volcanic eruptions, is in most cases not detectable, with the exception of large scale changes in indices linked to the frequency of cold night-time extremes. Our event analyses estimate how anthropogenic forcings alter the chances of getting new record index values in Europe and find that such extremes would be markedly rare if human influence were not accounted for, whereas in the current climate their return times range from a few years to a few decades.

  14. EVOLUTION OF TROPOSPHERIC TEMPERATURE FIELDS AND CORRESPONDING THERMAL MECHANISMS BEFORE/AFTER ONSET PERIODS OF ASIAN SUMMER MONSOON

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The evolution of the tropospheric temperature fields over Indian and South China Sea monsoon areas and their thermal mechanisms are compared and analyzed during the period from March to June, 1996. The results show that the onsets of the Indian and South China Sea summer monsoons are closely associated with the seasonal warming in the troposphere over the zonal belt of 10° N ~ 30° N in these areas, which leads to the inversion of meridional temperature gradient. During the pre-onset period, the warming over the South China Sea monsoon region is mainly due to the warm horizontal advection and diabatic (latent) heating processes. Meanwhile, the warming is suppressed by the vertical adiabatic process (cooling). In spring over the Indian monsoon region, the significant adiabatic heating due to the subsidence motion, which compensates the cooling due to the strong cold advection and diabatic cooling processes, results in a larger warming rate than over the South China Sea monsoon region. However, the meridional temperature gradient over the Indian monsoon region is so large during the late winter and early spring that it takes longer time to warm the troposphere to have the reversion of meridional temperature gradient than it does over the South China Sea monsoon region. It results in the phenomenon that the South China Sea summer monsoon generally breaks out earlier than the Indian summer monsoon.

  15. Fault Tolerant Magnetic Bearing Testing and Conical Magnetic Bearing Development for Extreme Temperature Environments

    Science.gov (United States)

    Keith, Theo G., Jr.; Clark, Daniel

    2004-01-01

    During the six month tenure of the grant, activities included continued research of hydrostatic bearings as a viable backup-bearing solution for a magnetically levitated shaft system in extreme temperature environments (1000 F), developmental upgrades of the fault-tolerant magnetic bearing rig at the NASA Glenn Research Center, and assisting in the development of a conical magnetic bearing for extreme temperature environments, particularly turbomachinery. It leveraged work from the ongoing Smart Efficient Components (SEC) and the Turbine-Based Combined Cycle (TBCC) program at NASA Glenn Research Center. The effort was useful in providing technology for more efficient and powerful gas turbine engines.

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

    Science.gov (United States)

    Guan, Yinghui

    2017-04-01

    The variability of surface air temperature and precipitation extremes has been the focus of attention during the past several decades, and may exert a great influence on the global hydrologic cycle and energy balance through thermal forcing. Using daily minimum (TN), maximum temperature (TX) and precipitation from 143 meteorological stations in the Yangtze River Basin (YRB), a suite of extreme climate indices recommended by the Expert Team on Climate Change Detection and Indices, which has rarely been applied in this region, were computed and analyzed during 1960-2012. The results show widespread significant changes in all temperature indices associated with warming in the YRB during 1960-2012. On the whole, cold-related indices, i.e., cold nights, cold days, frost days, icing days and cold spell duration index significantly decreased by -3.45, -1.03, -3.04, -0.42 and -1.6 days/decade, respectively. In contrast, warm-related indices such as warm nights, warm days, summer days, tropical nights and warm spell duration index significantly increased by 2.95, 1.71, 2.16, 1.05 and 0.73 days/decade. Minimum TN, maximum TN, minimum TX and maximum TX increased significantly by 0.42, 0.18, 0.19 and 0.14 °C/decade. Because of a faster increase in minimum temperature than maximum temperature, the diurnal temperature range (DTR) exhibited a significant decreasing trend of -0.09 °C/decade for the whole YRB during 1960-2012. Geographically, stations in the eastern Tibet Plateau and northeastern YRB showed stronger trends in almost all temperature indices. Time series analysis indicated that the YRB was dominated by a general cooling trend before the mid-1980s, but a warming trend afterwards. For precipitation, simple daily intensity index, very wet day precipitation, extremely wet day precipitation, extremely heavy precipitation days, maximum 1-day precipitation, maximum 5-day precipitation and maximum consecutive dry days all increased significantly during 1960-2012. In

  17. Projected changes of summer monsoon extremes and hydroclimatic regimes over West Africa for the twenty-first century

    Science.gov (United States)

    Diallo, Ismaïla; Giorgi, Filippo; Deme, Abdoulaye; Tall, Moustapha; Mariotti, Laura; Gaye, Amadou T.

    2016-12-01

    We use two CORDEX-Africa simulations performed with the regional model RegCM4 to characterize the projected changes in extremes and hydroclimatic regimes associated with the West African Monsoon (WAM). RegCM4 was driven for the period 1970-2100 by the HadGEM2-ES and the MPI-ESM Global Climate Models (GCMs) under the RCP8.5 greenhouse gas concentration pathway. RegCM4 accurately simulates the WAM characteristics in terms of seasonal mean, seasonal cycle, interannual variability and extreme events of rainfall. Overall, both RegCM4 experiments are able to reproduce the large-scale atmospheric circulation for the reference period (i.e. present-day), and in fact show improved performance compared to the driving GCMs in terms of precipitation mean climatology and extreme events, although different shortcomings in the various models are still evident. Precipitation is projected to decrease (increase) over western (eastern) Sahel, although with different spatial detail between RegCM4 and the corresponding driving GCMs. Changes in extreme precipitation events show patterns in line with those of the mean change. The models project different changes in water budget over the Sahel region, where the MPI projects an increased deficit in local moisture supply (E P). The E-P change is primarily precipitation driven. The precipitation increases over the eastern and/or central Sahel are attributed to the increase of moisture convergence due to increased water vapor in the boundary layer air column and surface evaporation. On the other hand, the projected dry conditions over the western Sahel are associated with the strengthening of moisture divergence in the upper level (850-300 hPa) combined to both a southward migration of the African Easterly Jet (AEJ) and a weakening of rising motion between the core of the AEJ and the Tropical Easterly Jet.

  18. A Newly-Discovered GPD-GEV Relationship Together with Comparing Their Models of Extreme Precipitation in Summer

    Institute of Scientific and Technical Information of China (English)

    DING Yuguo; CHENG Bingyan; JIANG Zhihong

    2008-01-01

    It has been theoretically proven that at a high threshold an approximate expression for a quantile of GEV (Generalized Extreme Values) distribution can be derived from GPD (Generalized Pareto Distribu-tion). Afterwards, a quantile of extreme rainfall events in a certain return period is found using L-moment estimation and extreme rainfall events simulated by GPD and GEV, with all aspects of their results com-pared. Numerical simulations show that POT (Peaks Over Threshold)-based GPD is advantageous in its simple operation and subjected to practically no effect of the sample size of the primitive series, producing steady high-precision fittings in the whole field of values (including the high-end heavy tailed). In compari-son, BM (Block Maximum)-based GEV is limited, to some extent, to the probability and quantile simulation, thereby showing that GPD is an extension of GEV, the former being of greater utility and higher significance to climate research compared to the latter.

  19. Climate change and the effects of temperature extremes on Australian flying-foxes.

    Science.gov (United States)

    Welbergen, Justin A; Klose, Stefan M; Markus, Nicola; Eby, Peggy

    2008-02-22

    Little is known about the effects of temperature extremes on natural systems. This is of increasing concern now that climate models predict dramatic increases in the intensity, duration and frequency of such extremes. Here we examine the effects of temperature extremes on behaviour and demography of vulnerable wild flying-foxes (Pteropus spp.). On 12 January 2002 in New South Wales, Australia, temperatures exceeding 42 degrees C killed over 3500 individuals in nine mixed-species colonies. In one colony, we recorded a predictable sequence of thermoregulatory behaviours (wing-fanning, shade-seeking, panting and saliva-spreading, respectively) and witnessed how 5-6% of bats died from hyperthermia. Mortality was greater among the tropical black flying-fox, Pteropus alecto (10-13%) than the temperate grey-headed flying-fox, Pteropus poliocephalus (less than 1%), and young and adult females were more affected than adult males (young, 23-49%; females, 10-15%; males, less than 3%). Since 1994, over 30000 flying-foxes (including at least 24500 P. poliocephalus) were killed during 19 similar events. Although P. alecto was relatively less affected, it is currently expanding its range into the more variable temperature envelope of P. poliocephalus, which increases the likelihood of die-offs occurring in this species. Temperature extremes are important additional threats to Australian flying-foxes and the ecosystem services they provide, and we recommend close monitoring of colonies where temperatures exceeding 42.0 degrees C are predicted. The effects of temperature extremes on flying-foxes highlight the complex implications of climate change for behaviour, demography and species survival.

  20. Spring land temperature anomalies in northwestern US and the summer drought over Southern Plains and adjacent areas

    Science.gov (United States)

    Xue, Yongkang; Oaida, Catalina M.; Diallo, Ismaila; Neelin, J. David; Li, Suosuo; De Sales, Fernando; Gu, Yu; Robinson, David A.; Vasic, Ratko; Yi, Lan

    2016-04-01

    Recurrent drought and associated heatwave episodes are important features of the US climate. Many studies have examined the connection between ocean surface temperature changes and conterminous US droughts. However, remote effects of large-scale land surface temperature variability, over shorter but still considerable distances, on US regional droughts have been largely ignored. The present study combines two types of evidence to address these effects: climate observations and model simulations. Our analysis of observational data shows that springtime land temperature in northwest US is significantly correlated with summer rainfall and surface temperature changes in the US Southern Plains and its adjacent areas. Our model simulations of the 2011 Southern Plains drought using a general circulation model and a regional climate model confirm the observed relationship between land temperature anomaly and drought, and suggest that the long-distance effect of land temperature changes in the northwest US on Southern Plains droughts is probably as large as the more familiar effects of ocean surface temperatures and atmospheric internal variability. We conclude that the cool 2011 springtime climate conditions in the northwest US increased the probability of summer drought and abnormal heat in the Southern Plains. The present study suggests a strong potential for more skillful intra-seasonal predictions of US Southern Plains droughts when such facts as ones presented here are considered.

  1. The effects of anesthetic technique and ambient temperature on thermoregulation in lower extremity surgery.

    Science.gov (United States)

    Ozer, Ayse B; Tosun, Fadime; Demirel, Ismail; Unlu, Serap; Bayar, Mustafa K; Erhan, Omer L

    2013-08-01

    The purpose of our study was to determine the effects of anesthetic technique and ambient temperature on thermoregulation for patients undergoing lower extremity surgery. Our study included 90 male patients aged 18-60 years in American Society of Anesthesiologists Physical Status groups I or II who were scheduled for lower extremity surgery. Patients were randomly divided into three groups according to anesthetic technique: general anesthesia (GA), epidural anesthesia (EA), and femoral-sciatic block (FS). These groups were divided into subgroups according to room temperature: the temperature for group I was 20-22 °C and that for group II was 23-25 °C. Therefore, we labeled the groups as follows: GA I, GA II, EA I, EA II, FS I, and FS II. Probes for measuring tympanic membrane and peripheral temperature were placed in and on the patients, and mean skin temperature (MST) and mean body temperature (MBT) were assessed. Postoperative shivering scores were recorded. During anesthesia, tympanic temperature and MBT decreased whereas MST increased for all patients. There was no significant difference between tympanic temperatures in either the room temperature or anesthetic method groups. MST was lower in group GA I than in group GA II after 5, 10, 15, 20, 60 and 90 min whereas MBT was significantly lower at the basal level (p thermoregulation among anesthetic techniques. Room temperature affected thermoregulation in Group GA.

  2. The Impact of Morphological Features on Summer Temperature Variations on the Example of Two Residential Neighborhoods in Ljubljana, Slovenia

    OpenAIRE

    Alenka Fikfak; Saja Kosanović; Miha Konjar; Janez P. Grom; Martina Zbašnik-Senegačnik

    2017-01-01

    The study conducted in this paper is focused on a predominantly residential area of the City of Ljubljana—Koseze, which is characterized by generally favorable (bio)climatic conditions. Nonetheless, thermal satellite images showed that residential neighborhoods within the Koseze district display unexpected variations in summer temperatures. This observation called into question the benefits of existing bioclimatic features and indicated the need to investigate and compare two neighborhoods wi...

  3. The non-Gaussianity and spatial asymmetry of temperature extremes relative to the jet: the role of horizontal advection

    Science.gov (United States)

    Harnik, Nili; Garfinkel, Chaim

    2016-04-01

    Global warming is expected raise the number of warm spells and lower the number of cold spells, by simply shifting of the near-surface temperature probability distribution to warmer temperatures. However, changes in the shape of distribution strongly affect how the occurrence of temperature extremes will change. Hence, understanding the processes shaping the spatial and statistical distribution of temperature variations and extremes in the present climate is central to understanding how temperature extremes might vary in the future. Using meteorological reanalyses data we show that the distribution of near-surface temperature variability is non-Gaussian, and consistent with this, extreme warm anomalies occur preferentially poleward of the location of extreme cold anomalies. The non-Guassianity evident in reanalysis data is also found in a set of dry General Circulation Model runs in which the jet is forced at different latitudes, and the location of extremes is influenced by the location of the jet stream. Using a simple model of Lagrangian temperature advection, we investigate the role of synoptic dynamics in causing this non Gaussianity. The meridional shifting between cold and warm extremes, and the related non-Gaussianity are traced back to the synoptic evolution leading up to cold and warm extreme events. We find that the meridional movement of synotpic systems, as well as nonlinear temperature advection are both of crucial importance for the warm/cold asymmetry in the latitudinal distribution of the temperature extremes. The possible implications for future changes in extremes will be briefly discussed.

  4. Predicting Indian Summer Monsoon onset through variations of surface air temperature and relative humidity

    Science.gov (United States)

    Stolbova, Veronika; Surovyatkina, Elena; Kurths, Jurgen

    2015-04-01

    Indian Summer Monsoon (ISM) rainfall has an enormous effect on Indian agriculture, economy, and, as a consequence, life and prosperity of more than one billion people. Variability of the monsoonal rainfall and its onset have a huge influence on food production, agricultural planning and GDP of the country, which on 22% is determined by agriculture. Consequently, successful forecasting of the ISM onset is a big challenge and large efforts are being put into it. Here, we propose a novel approach for predictability of the ISM onset, based on critical transition theory. The ISM onset is defined as an abrupt transition from sporadious rainfall to spatially organized and temporally sustained rainfall. Taking this into account, we consider the ISM onset as is a critical transition from pre-monsoon to monsoon, which take place in time and also in space. It allows us to suggest that before the onset of ISM on the Indian subcontinent should be areas of critical behavior where indicators of the critical transitions can be detected through an analysis of observational data. First, we identify areas with such critical behavior. Second, we use detected areas as reference points for observation locations for the ISM onset prediction. Third, we derive a precursor for the ISM onset based on the analysis of surface air temperature and relative humidity variations in these reference points. Finally, we demonstrate the performance of this precursor on two observational data sets. The proposed approach allows to determine ISM onset in advance in 67% of all considered years. Our proposed approach is less effective during the anomalous years, which are associated with weak/strong monsoons, e.g. El-Nino, La-Nina or positive Indian Ocean Dipole events. The ISM onset is predicted for 23 out of 27 normal monsoon years (85%) during the past 6 decades. In the anomalous years, we show that time series analysis in both areas during the pre-monsoon period reveals indicators whether the

  5. Observed 1970-2005 cooling of summer daytime temperatures in coastal California

    Energy Technology Data Exchange (ETDEWEB)

    Lebassi, B.; Gonzalez, J.; Fabris, D.; Maurer, E.; Miller, N.; Milesi, C.; Bornstein, R.

    2009-05-15

    The study evaluated 1948-2004 summer (JJA) mean monthly air temperatures for two California air basins: SoCAB and SFBA. The study focuses on the more rapid post-1970 warming period, and its daily T{sub min} and T{sub max} values were used to produce average monthly values and spatial distributions of trends for each air basins. Additional analyses included T{sub D} values at two NWS sites, SSTs, NCEP reanalysis sea-level pressures, and GCM T{sub ave}-values. Results for all California COOP sites together showed increased JJA T{sub ave}-values; asymmetric warming, as T{sub min}-values increase faster than T{sub max}-values; and thus decreased DTR values. The spatial distribution of observed SoCAB and SFBA T{sub max} values exhibited a complex pattern, with cooling in low-elevation coastal-areas open to marine air penetration and warming at inland areas. Results also showed that decreased DTR values in the valleys arose from small increases at 'inland' sites combined with large decreases at 'coastal' sites. Previous studies suggest that cooling JJA T{sub max}-values in coastal California were due to increased irrigation, coastal upwelling, or cloud cover, while the current hypothesis is that they arises from GHG-induced global-warming of 'inland' areas, which results in increased sea breeze flow activity. Sea level pressure trends showed increases in the oceanic Pacific High and decreases in the central-California Thermal Low. The corresponding gradient thus showed a trend of 0.02 hPa 100-km{sup -1} decade{sup -1}, supportive of the hypothesis of increased sea breeze activity. Trends in T{sub D} values showed a larger value at coastal SFO than at inland SEC, which indicative of increased sea breeze activity; calculated SST trends (0.15 C decade{sup -1}) could also have increase T{sub D}-values. GCM model Tave-values showed warming that decreases from 0.13 C decade{sup -1} at inland California to 0.08 C decade{sup -1} at coastal areas

  6. Extreme Sensitivity of Room-Temperature Photoelectric Effect for Terahertz Detection.

    Science.gov (United States)

    Huang, Zhiming; Zhou, Wei; Tong, Jinchao; Huang, Jingguo; Ouyang, Cheng; Qu, Yue; Wu, Jing; Gao, Yanqing; Chu, Junhao

    2016-01-01

    Extreme sensitivity of room-temperature photoelectric effect for terahertz (THz) detection is demonstrated by generating extra carriers in an electromagnetic induced well located at the semiconductor, using a wrapped metal-semiconductor-metal configuration. The excellent performance achieved with THz detectors shows great potential to open avenues for THz detection.

  7. How to apply the dependence structure analysis to extreme temperature and precipitation for disaster risk assessment

    Science.gov (United States)

    Feng, Jieling; Li, Ning; Zhang, Zhengtao; Chen, Xi

    2017-06-01

    IPCC reports that a changing climate can affect the frequency and the intensity of extreme events. However, the extremes appear in the tail of the probability distribution. In order to know the relationship between extreme events in the tail of temperature and precipitation, an important but previously unobserved dependence structure is analyzed in this paper. Here, we examine the dependence structure by building a bivariate joint of Gumbel copula model for temperature and precipitation using monthly average temperature (T) and monthly precipitation (P) data from Beijing station in China covering a period of 1951-2015 and find the dependence structure can be divided into two sections, they are the middle part and the upper tail. We show that T and P have a strong positive correlation in the high tail section (T > 25.85 °C and P > 171.1 mm) (=0.66, p < 0.01) while they do not demonstrate the same relation in the other section, which suggests that the identification of a strong influence of T on extreme P needs help from the dependence structure analysis. We also find that in the high tail section, every 1 °C increase in T is associated with 73.45 mm increase in P. Our results suggested that extreme precipitation fluctuations by changes in temperature will allow the data dependence structure to be included in extreme affect for the disaster risk assessment under future climate change scenarios. Copula bivariate jointed probability distribution is useful to the dependence structure analysis.

  8. Performance of the Micropower Voltage Reference ADR3430 Under Extreme Temperatures

    Science.gov (United States)

    Patterson, Richard L.; Hammoud, Ahmad

    2011-01-01

    Electronic systems designed for use in space exploration systems are expected to be exposed to harsh temperatures. For example, operation at cryogenic temperatures is anticipated in space missions such as polar craters of the moon (-223 C), James Webb Space Telescope (-236 C), Mars (-140 C), Europa (-223 C), Titan (-178 C), and other deep space probes away from the sun. Similarly, rovers and landers on the lunar surface, and deep space probes intended for the exploration of Venus are expected to encounter high temperature extremes. Electronics capable of operation under extreme temperatures would not only meet the requirements of future spacebased systems, but would also contribute to enhancing efficiency and improving reliability of these systems through the elimination of the thermal control elements that present electronics need for proper operation under the harsh environment of space. In this work, the performance of a micropower, high accuracy voltage reference was evaluated over a wide temperature range. The Analog Devices ADR3430 chip uses a patented voltage reference architecture to achieve high accuracy, low temperature coefficient, and low noise in a CMOS process [1]. The device combines two voltages of opposite temperature coefficients to create an output voltage that is almost independent of ambient temperature. It is rated for the industrial temperature range of -40 C to +125 C, and is ideal for use in low power precision data acquisition systems and in battery-powered devices. Table 1 shows some of the manufacturer s device specifications.

  9. Summer sea-surface temperatures and climate events on the North Icelandic shelf through the last 3000 years

    Institute of Scientific and Technical Information of China (English)

    JIANG Hui; REN Jian; Karen Luise KNUDSEN; Jón EIRíKSSON3; RAN LiHua

    2007-01-01

    Diatom data from core MD992271 on the North Icelandic shelf record a cooling trend through the last 3000 years. This is indicated by a general decrease in warm water species and an increase in cold water taxa. The relative abundance of these two diatom groups changed periodically, suggesting that the climate also fluctuated within this time period. The results of diatom-based transfer function calculation show that the summer sea-surface temperatures (SSTs) before 1400 cai. a BP were generally higher than the mean value for the last 3000 years and the summer SSTs fluctuated around the mean between 1400 and 700 cal. a BP, and dropped to the values below the mean after 700 cal. a BP. Four cooling events were distinguished, centered at around 2600, 1900, 1300 and 600 cal. a BP respectively. The results are not only consistent with the data from neighbouring cores HM107-03 and MD992275, but also comparable with those from the GISP2 ice core and from other marine sediment records in the North Atlantic. This suggests that changes in the summer SSTs reflect regional climate variations in the North Atlantic. On the North Icelandic shelf, the summer SST variation is a result of changes in the interaction between the cold and the warm currents in the area.

  10. Effects of forest harvesting on summer stream temperatures in New Brunswick, Canada: an inter-catchment, multiple-year comparison

    Directory of Open Access Journals (Sweden)

    C. P.-A. Bourque

    2001-01-01

    Full Text Available This paper presents a pre- and post-harvest comparison of stream temperatures collected in five neighbouring streams (sub-catchments over a period of five years (1994-1998. The aim of the study was to determine whether land cover changes from clear cutting in areas outside forest buffer zones (applied to streams >0.5 m wide might contribute to an increase in summer mean stream temperatures in buffered streams downslope by infusion of warmed surface and sub-surface water into the streams. Specific relationships were observed in all five forest streams investigated. To assist in the analysis, several spatially-relevant variables, such as land cover change, mid-summer potential solar radiation, flow accumulation, stream location and slope of the land were determined, in part, from existing aerial photographs, GIS-archived forest inventory data and a digital terrain model of the study area. Spatial calculations of insolation levels for July 15th were used as an index of mid-summer solar heating across sub-catchments. Analysis indicated that prior to the 1995 harvest, differences in stream temperature could be attributed to (i topographic position and catchment-to-sun orientation, (ii the level of cutting that occurred in the upper catchment prior to the start of the study, and (iii the average slope within harvested areas. Compared to the pre-harvest mean stream temperatures in 1994, mean temperatures in the three streams downslope from the 1995 harvest areas increased by 0.3 to 0.7°C (representing a 4-8% increase; p-value of normalised temperatures Keywords: terrain attributes, solar radiation, land cover, forest buffers, New Brunswick regulations, spatial modelling, DEM, forest covertypes

  11. Variations in morphological and life-history traits under extreme temperatures in Drosophila ananassae

    Indian Academy of Sciences (India)

    Seema Sisodia; B N Singh

    2009-06-01

    Using half-sib analysis, we analysed the consequences of extreme rearing temperatures on genetic and phenotypic variations in the morphological and life-history traits of Drosophila ananassae. Paternal half-sib covariance contains a relatively small proportion of the epistatic variance and lacks the dominance variance and variance due to maternal effect, which provides more reliable estimates of additive genetic variance. Experiments were performed on a mass culture population of D. ananassae collected from Kanniyakumari (India). Two extremely stressful temperatures (18°C and 32°C) and one standard temperature (25°C) were used to examine the effect of stressful and non-stressful environments on the morphological and life-history traits in males and females. Mean values of various morphological traits differed significantly among different temperature regimens in both males and females. Rearing at 18°C and 32°C resulted in decreased thorax length, wing-to-thorax (w/t) ratio, sternopleural bristle number, ovariole number, sex comb-tooth number and testis length. Phenotypic variances increased under stressful temperatures in comparison with non-stressful temperatures. Heritability and evolvability based on among-sires (males), among-dams (females), and the sum of the two components (sire + dam) showed higher values at both the stressful temperatures than at the non-stressful temperature. These differences reflect changes in additive genetic variance. Viability was greater at the high than the low extreme temperature. As viability is an indicator of stress, we can assume that stress was greater at 18°C than at 32°C in D. ananassae. The genetic variations for all the quantitative and life-history traits were higher at low temperature. Variation in sexual traits was more pronounced as compared with other morphometric traits, which shows that sexual traits are more prone to thermal stress. Our results agree with the hypothesis that genetic variation is increased in

  12. Impact of the North Atlantic Sea Surface Temperature Tripole on the East Asian Summer Monsoon

    Institute of Scientific and Technical Information of China (English)

    ZUO Jinqing; LI Weijing; SUN Chenghu; XU Li; REN Hong-Li

    2013-01-01

    A strong (weak) East Asian summer monsoon (EASM) is usually concurrent with the tripole pattern of North Atlantic SST anomalies on the interannual timescale during summer,which has positive (negative)SST anomalies in the northwestern North Atlantic and negative (positive) SST anomalies in the subpolar and tropical ocean.The mechanisms responsible for this linkage are diagnosed in the present study.It is shown that a barotropic wave-train pattern occurring over the Atlantic-Eurasia region likely acts as a link between the EASM and the SST tripole during summer.This wave-train pattern is concurrent with geopotential height anomalies over the Ural Mountains,which has a substantial effect on the EASM.Diagnosis based on observations and linear dynamical model results reveals that the mechanism for maintaining the wave-train pattern involves both the anomalous diabatic heating and synoptic eddy-vorticity forcing.Since the North Atlantic SST tripole is closely coupled with the North Atlantic Oscillation (NAO),the relationships between these two factors and the EASM are also examined.It is found that the connection of the EASM with the summer SST tripole is sensitive to the meridional location of the tripole,which is characterized by large seasonal variations due to the north-south movement of the activity centers of the NAO.The SST tripole that has a strong relationship with the EASM appears to be closely coupled with the NAO in the previous spring rather than in the simultaneous summer.

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

    Science.gov (United States)

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

    2016-04-01

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

  14. Extreme temperature robust optical sensor designs and fault-tolerant signal processing

    Energy Technology Data Exchange (ETDEWEB)

    Riza, Nabeel Agha (Oviedo, FL); Perez, Frank (Tujunga, CA)

    2012-01-17

    Silicon Carbide (SiC) probe designs for extreme temperature and pressure sensing uses a single crystal SiC optical chip encased in a sintered SiC material probe. The SiC chip may be protected for high temperature only use or exposed for both temperature and pressure sensing. Hybrid signal processing techniques allow fault-tolerant extreme temperature sensing. Wavelength peak-to-peak (or null-to-null) collective spectrum spread measurement to detect wavelength peak/null shift measurement forms a coarse-fine temperature measurement using broadband spectrum monitoring. The SiC probe frontend acts as a stable emissivity Black-body radiator and monitoring the shift in radiation spectrum enables a pyrometer. This application combines all-SiC pyrometry with thick SiC etalon laser interferometry within a free-spectral range to form a coarse-fine temperature measurement sensor. RF notch filtering techniques improve the sensitivity of the temperature measurement where fine spectral shift or spectrum measurements are needed to deduce temperature.

  15. Effects of extreme spring temperatures on phenology: a case study from Munich and Ingolstadt

    Science.gov (United States)

    Jochner, Susanne; Menzel, Annette

    2010-05-01

    Extreme events - e.g. warm spells or heavy precipitation events - are likely to increase in the future both in frequency and intensity. Therefore, research on extreme events gains new importance; also in terms of plant development which is mostly triggered by temperatures. An arising question is how plants respond to an extreme warm spell when following an extreme cold winter season. This situation could be studied in spring 2009 in the greater area of Munich and Ingolstadt by phenological observations of flowering and leaf unfolding of birch (Betula pendula L.) and flowering of horse chestnut (Aesculus hippocastanum L.). The long chilling period of winter 2008 and spring 2009 was followed by an immediate strong forcing of flowering and leaf unfolding, especially for birch. This extreme weather situation diminished the difference between urban and rural dates of onset. Another important fact that could be observed in the proceeding period of December 2008 to April 2009 was the reduced temperature difference among urban and rural sites (urban heat island effect). Long-term observations (1951-2008) of the phenological network of the German Meteorological Service (DWD) were used to identify years with reduced urban-rural differences between onset times in the greater area of Munich in the past. Statistical analyses were conducted in order to answer the question whether the sequence of extreme warm and cold events leads to a decreased difference in phenological onset times or if this behaviour can be attributed to extreme warm springs themselves or to the decreased urban heat island effect which is mostly affected by general atmospheric circulation patterns.

  16. Limits to the thermal tolerance of corals adapted to a highly fluctuating, naturally extreme temperature environment

    Science.gov (United States)

    Schoepf, Verena; Stat, Michael; Falter, James L.; McCulloch, Malcolm T.

    2015-12-01

    Naturally extreme temperature environments can provide important insights into the processes underlying coral thermal tolerance. We determined the bleaching resistance of Acropora aspera and Dipsastraea sp. from both intertidal and subtidal environments of the naturally extreme Kimberley region in northwest Australia. Here tides of up to 10 m can cause aerial exposure of corals and temperatures as high as 37 °C that fluctuate daily by up to 7 °C. Control corals were maintained at ambient nearshore temperatures which varied diurnally by 4-5 °C, while treatment corals were exposed to similar diurnal variations and heat stress corresponding to ~20 degree heating days. All corals hosted Symbiodinium clade C independent of treatment or origin. Detailed physiological measurements showed that these corals were nevertheless highly sensitive to daily average temperatures exceeding their maximum monthly mean of ~31 °C by 1 °C for only a few days. Generally, Acropora was much more susceptible to bleaching than Dipsastraea and experienced up to 75% mortality, whereas all Dipsastraea survived. Furthermore, subtidal corals, which originated from a more thermally stable environment compared to intertidal corals, were more susceptible to bleaching. This demonstrates that while highly fluctuating temperatures enhance coral resilience to thermal stress, they do not provide immunity to extreme heat stress events.

  17. Limits to the thermal tolerance of corals adapted to a highly fluctuating, naturally extreme temperature environment.

    Science.gov (United States)

    Schoepf, Verena; Stat, Michael; Falter, James L; McCulloch, Malcolm T

    2015-12-02

    Naturally extreme temperature environments can provide important insights into the processes underlying coral thermal tolerance. We determined the bleaching resistance of Acropora aspera and Dipsastraea sp. from both intertidal and subtidal environments of the naturally extreme Kimberley region in northwest Australia. Here tides of up to 10 m can cause aerial exposure of corals and temperatures as high as 37 °C that fluctuate daily by up to 7 °C. Control corals were maintained at ambient nearshore temperatures which varied diurnally by 4-5 °C, while treatment corals were exposed to similar diurnal variations and heat stress corresponding to ~20 degree heating days. All corals hosted Symbiodinium clade C independent of treatment or origin. Detailed physiological measurements showed that these corals were nevertheless highly sensitive to daily average temperatures exceeding their maximum monthly mean of ~31 °C by 1 °C for only a few days. Generally, Acropora was much more susceptible to bleaching than Dipsastraea and experienced up to 75% mortality, whereas all Dipsastraea survived. Furthermore, subtidal corals, which originated from a more thermally stable environment compared to intertidal corals, were more susceptible to bleaching. This demonstrates that while highly fluctuating temperatures enhance coral resilience to thermal stress, they do not provide immunity to extreme heat stress events.

  18. Climate Change and Fetal Health: The Impacts of Exposure to Extreme Temperatures in New York City

    Science.gov (United States)

    Ngo, Nicole S.; Horton, Radley M.

    2015-01-01

    Background: Climate change is projected to increase the frequency, intensity, and duration of heat waves while reducing cold extremes, yet few studies have examined the relationship between temperature and fetal health. Objectives: We estimate the impacts of extreme temperatures on birth weight and gestational age in Manhattan, a borough in New York City, and explore differences by socioeconomic status (SES). Methods: We combine average daily temperature from 1985 to 2010 with birth certificate data in Manhattan for the same time period. We then generate 33 downscaled climate model time series to project impacts on fetal health. Results: We find exposure to an extra day where average temperature 25 F and 85 F during pregnancy is associated with a 1.8 and 1.7 g (respectively) reduction in birth weight, but the impact varies by SES, particularly for extreme heat, where teen mothers seem most vulnerable. We find no meaningful, significant effect on gestational age. Using projections of temperature from these climate models, we project average net reductions in birth weight in the 2070- 2099 period of 4.6 g in the business-as-usual scenario. Conclusions: Results suggest that increasing heat events from climate change could adversely impact birth weight and vary by SES.

  19. Climate Change and Fetal Health: The Impacts of Exposure to Extreme Temperatures in New York City

    Science.gov (United States)

    Ngo, Nicole S.; Horton, Radley M.

    2015-01-01

    Background: Climate change is projected to increase the frequency, intensity, and duration of heat waves while reducing cold extremes, yet few studies have examined the relationship between temperature and fetal health. Objectives: We estimate the impacts of extreme temperatures on birth weight and gestational age in Manhattan, a borough in New York City, and explore differences by socioeconomic status (SES). Methods: We combine average daily temperature from 1985 to 2010 with birth certificate data in Manhattan for the same time period. We then generate 33 downscaled climate model time series to project impacts on fetal health. Results: We find exposure to an extra day where average temperature 25 F and 85 F during pregnancy is associated with a 1.8 and 1.7 g (respectively) reduction in birth weight, but the impact varies by SES, particularly for extreme heat, where teen mothers seem most vulnerable. We find no meaningful, significant effect on gestational age. Using projections of temperature from these climate models, we project average net reductions in birth weight in the 2070- 2099 period of 4.6 g in the business-as-usual scenario. Conclusions: Results suggest that increasing heat events from climate change could adversely impact birth weight and vary by SES.

  20. Greater increases in temperature extremes in low versus high income countries

    Science.gov (United States)

    Herold, Nicholas; Alexander, Lisa; Green, Donna; Donat, Markus

    2017-03-01

    It is commonly expected that the world’s lowest income countries will face some of the worst impacts of global warming, despite contributing the least to greenhouse gas emissions. Using global atmospheric reanalyses we show that the world’s lowest income countries are already experiencing greater increases in the occurrence of temperature extremes compared to the highest income countries, and have been for over two decades. Not only are low income countries less able to support mitigation and adaptation efforts, but their typically equatorial location predisposes them to lower natural temperature variability and thus greater changes in the occurrence of temperature extremes with global warming. This aspect of global warming is well known but overlooked in current international climate policy agreements and we argue that it is an important factor in reducing inequity due to climate impacts.

  1. Inelastic X-ray scattering experiments at extreme conditions: high temperatures and high pressures

    Directory of Open Access Journals (Sweden)

    S.Hosokawa

    2008-03-01

    Full Text Available In this article, we review the present status of experimental techniques under extreme conditions of high temperature and high pressure used for inelastic X-ray scattering (IXS experiments of liquid metals, semiconductors, molten salts, molecular liquids, and supercritical water and methanol. For high temperature experiments, some types of single-crystal sapphire cells were designed depending on the temperature of interest and the sample thickness for the X-ray transmission. Single-crystal diamond X-ray windows attached to the externally heated high-pressure vessel were used for the IXS experiment of supercritical water and methanol. Some typical experimental results are also given, and the perspective of IXS technique under extreme conditions is discussed.

  2. Year aridity index patterns in northwest China and the relationship to summer North Atlantic sea surface temperature

    Institute of Scientific and Technical Information of China (English)

    YAN Yan; ZHAO Xinyi; ZHOU Liping

    2008-01-01

    Aim to linking the variability of drought in northwest China to the oceanic influence of North Atlantic SSTs at the background of global warming and at the regional climate change shifting stages, year aridity index variations in northwest China and summer North Atlantic sea surface temperature (SST) variations are examined for the 44 a period of 1961--2004 using singular value de-composition (SVD) analysis. Results show that the SST anomalies (SSTA) in the North Atlantic in summer reflected three basic models. The first SVD mode of SST pattern shows a dipole - like variation with the positive center located at southwest and nega-tive center at northeast of extratropical North Atlantic. And it strongly relates to the positive trend in AI variation in northwest China. The second coupled modes display the coherent positive anomalies in extratropical North Atlantic SST and the marked opposite trend of AI variability between north and south of Xinjiang. In addition, the lag correlation analysis of the first mode of SSTA and geopotential heights at 500 hPa variations also shows that the indication of the former influencing the latter configuration, which re-sult in higher air temperature and less precipitation when the SSTA in the North Atlantic Ocean in summer motivated Eurasian cir-culation of EA pattern, further to influence the wet - dry variations in northwest China by the ocean-to - atmosphere forcing.

  3. Characterization of Future Caribbean Rainfall and Temperature Extremes across Rainfall Zones

    Directory of Open Access Journals (Sweden)

    Natalie Melissa McLean

    2015-01-01

    Full Text Available End-of-century changes in Caribbean climate extremes are derived from the Providing Regional Climate for Impact Studies (PRECIS regional climate model (RCM under the A2 and B2 emission scenarios across five rainfall zones. Trends in rainfall, maximum temperature, and minimum temperature extremes from the RCM are validated against meteorological stations over 1979–1989. The model displays greater skill at representing trends in consecutive wet days (CWD and extreme rainfall (R95P than consecutive dry days (CDD, wet days (R10, and maximum 5-day precipitation (RX5. Trends in warm nights, cool days, and warm days were generally well reproduced. Projections for 2071–2099 relative to 1961–1989 are obtained from the ECHAM5 driven RCM. Northern and eastern zones are projected to experience more intense rainfall under A2 and B2. There is less consensus across scenarios with respect to changes in the dry and wet spell lengths. However, there is indication that a drying trend may be manifest over zone 5 (Trinidad and northern Guyana. Changes in the extreme temperature indices generally suggest a warmer Caribbean towards the end of century across both scenarios with the strongest changes over zone 4 (eastern Caribbean.

  4. Trends in Extremes of Surface Humidity, Temperature, and Summertime Heat Stress in China

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In the past half century, the mean summertime temperature in China has increased, with nights warm ing more than days. Using surface station observations, we show that the frequency of extreme heat-stress events in China, caused by extremely hot and humid days as well as by heatwaves lasting for a few days, has increased over the period from 1951 to 1994. When humidity is high, hot weather can cause heat stress in humans. The increased heat-stress trend may pose a public health problem.

  5. Recent trends in pre-monsoon daily temperature extremes over India

    Indian Academy of Sciences (India)

    D R Kothawale; J V Revadekar; K Rupa Kumar

    2010-02-01

    Extreme climate and weather events are increasingly being recognized as key aspects of climate change. Pre-monsoon season (March–May) is the hottest part of the year over almost the entire South Asian region, in which hot weather extremes including heat waves are recurring natural hazards having serious societal impacts, particularly on human health. In the present paper, recent trends in extreme temperature events for the pre-monsoon season have been studied using daily data on maximum and minimum temperatures over a well-distributed network of 121 stations for the period 1970–2005. For this purpose, time series of extreme temperature events have been constructed for India as a whole and seven homogeneous regions, viz., Western Himalaya (WH), Northwest (NW), Northeast (NE), North Central (NC), East coast (EC), West coast (WC) and Interior Peninsula (IP). In general, the frequency of occurrence of hot days and hot nights showed widespread increasing trend, while that of cold days and cold nights has shown widespread decreasing trend. The frequency of the occurrence of hot days is found to have significantly increased over EC, WC and IP, while that of cold days showed significant decreasing trend over WH and WC. The three regions EC, WC and NW showed significant increasing trend in the frequency of hot nights. For India as whole, the frequency of hot days and nights showed increasing trend while cold days and nights showed decreasing trends. Day-to-day fluctuations of pre-monsoon daily maximum and minimum temperatures have also been studied for the above regions. The results show that there is no significant change in day-to-day magnitude of fluctuations of pre-monsoon maximum and minimum temperatures. However, the results generally indicate that the daily maximum and minimum temperatures are becoming less variable within the season.

  6. Indian summer monsoon rainfall variability during 2014 and 2015 and associated Indo-Pacific upper ocean temperature patterns

    Science.gov (United States)

    Kakatkar, Rashmi; Gnanaseelan, C.; Chowdary, J. S.; Parekh, Anant; Deepa, J. S.

    2017-01-01

    In this study, factors responsible for the deficit Indian Summer Monsoon (ISM) rainfall in 2014 and 2015 and the ability of Indian Institute of Tropical Meteorology-Global Ocean Data Assimilation System (IITM-GODAS) in representing the oceanic features are examined. IITM-GODAS has been used to provide initial conditions for seasonal forecast in India during 2014 and 2015. The years 2014 and 2015 witnessed deficit ISM rainfall but were evolved from two entirely different preconditions over Pacific. This raises concern over the present understanding of the role of Pacific Ocean on ISM variability. Analysis reveals that the mechanisms associated with the rainfall deficit over the Indian Subcontinent are different in the two years. It is found that remote forcing in summer of 2015 due to El Niño is mostly responsible for the deficit monsoon rainfall through changes in Walker circulation and large-scale subsidence. In the case of the summer of 2014, both local circulation with anomalous anticyclone over central India and intrusion of mid-latitude dry winds from north have contributed for the deficit rainfall. In addition to the above, Tropical Indian Ocean (TIO) sea surface temperature (SST) and remote forcing from Pacific Ocean also modulated the ISM rainfall. It is observed that Pacific SST warming has extended westward in 2014, making it a basin scale warming unlike the strong El Niño year 2015. The eastern equatorial Indian Ocean is anomalously warmer than west in summer of 2014, and vice versa in 2015. These differences in SST in both tropical Pacific and TIO have considerable impact on ISM rainfall in 2014 and 2015. The study reveals that initializing coupled forecast models with proper upper ocean temperature over the Indo-Pacific is therefore essential for improved model forecast. It is important to note that the IITM-GODAS which assimilates only array for real-time geostrophic oceanography (ARGO) temperature and salinity profiles could capture most of the

  7. Dynamically-downscaled projections of changes in temperature extremes over China

    Science.gov (United States)

    Guo, Junhong; Huang, Guohe; Wang, Xiuquan; Li, Yongping; Lin, Qianguo

    2017-06-01

    In this study, likely changes in extreme temperatures (including 16 indices) over China in response to global warming throughout the twenty-first century are investigated through the PRECIS regional climate modeling system. The PRECIS experiment is conducted at a spatial resolution of 25 km and is driven by a perturbed-physics ensemble to reflect spatial variations and model uncertainties. Simulations of present climate (1961-1990) are compared with observations to validate the model performance in reproducing historical climate over China. Results indicate that the PRECIS demonstrates reasonable skills in reproducing the spatial patterns of observed extreme temperatures over the most regions of China, especially in the east. Nevertheless, the PRECIS shows a relatively poor performance in simulating the spatial patterns of extreme temperatures in the western mountainous regions, where its driving GCM exhibits more uncertainties due to lack of insufficient observations and results in more errors in climate downscaling. Future spatio-temporal changes of extreme temperature indices are then analyzed for three successive periods (i.e., 2020s, 2050s and 2080s). The projected changes in extreme temperatures by PRECIS are well consistent with the results of the major global climate models in both spatial and temporal patterns. Furthermore, the PRECIS demonstrates a distinct superiority in providing more detailed spatial information of extreme indices. In general, all extreme indices show similar changes in spatial pattern: large changes are projected in the north while small changes are projected in the south. In contrast, the temporal patterns for all indices vary differently over future periods: the warm indices, such as SU, TR, WSDI, TX90p, TN90p and GSL are likely to increase, while the cold indices, such as ID, FD, CSDI, TX10p and TN10p, are likely to decrease with time in response to global warming. Nevertheless, the magnitudes of changes in all indices tend to

  8. Multi-Model Projection of July-August Climate Extreme Changes over China under CO2 Doubling. Part II: Temperature

    Institute of Scientific and Technical Information of China (English)

    LI Hongmei; FENG Lei; ZHOU Tianjun

    2011-01-01

    This is the second part of the authors' analysis on the output of 24 coupled climate models from the Twentieth-Century Climate in Coupled Models (20C3M) experiment and 1% per year CO2 increase experiment (to doubling) (lpctto2x) of phase 3 of the Coupled Model Inter-comparison Project (CMIP3). The study focuses on the potential changes of July-August temperature extremes over China. The pattern correlation coefficients of the simulated temperature with the observations are 0.6-0.9, which are higher than the results for precipitation. However, most models have cold bias compared to observation, with a larger cold bias over western China (>5℃) than over eastern China (<2℃). The multi-model ensemble (MME)exhibits a significant increase of temperature under the lpctto2x scenario. The amplitude of the MME warming shows a northwest-southeast decreasing gradient. The warming spread among the models (~1℃-2℃) is less than MME warming (~2℃-4℃), indicating a relativelyrobust temperature change under CO2doubling. Further analysis of Geophysical Fluid Dynamics Laboratory coupled climate model version 2.1(GFDL-CM2.1) simulations suggests that the warming pattern may be related to heat transport by summer monsoons. The contrast of cloud effects also has contributions. The different vertical structures of warming over northwestern China and southeastern China may be attributed to the different natures of vertical circulations. The deep, moist convection over southeastern China is an effective mechanism for "transporting"the warming upward, leading to more upper-level warming. In northwestern China, the warming is more surface-orientated, possibly due to the shallow, dry convection.

  9. Statistical modelling of wildfire size and intensity: a step toward meteorological forecasting of summer extreme fire risk

    OpenAIRE

    Hernandez, C; Keribin, C.; Drobinski, P.; Turquety, S.

    2015-01-01

    International audience; In this article we investigate the use of statistical methods for wildfire risk assessment in the Mediterranean Basin using three meteorological covariates, the 2 m temperature anomaly, the 10 m wind speed and the January– June rainfall occurrence anomaly. We focus on two remotely sensed characteristic fire variables, the burnt area (BA) and the fire radiative power (FRP), which are good proxies for fire size and intensity respectively. Using the fire data we determine...

  10. The long summer: pre-wintering temperatures affect metabolic expenditure and winter survival in a solitary bee.

    Science.gov (United States)

    Sgolastra, Fabio; Kemp, William P; Buckner, James S; Pitts-Singer, Theresa L; Maini, Stefano; Bosch, Jordi

    2011-12-01

    The impact of climate change on insect populations depends on specific life cycle traits and physiological adaptations. The solitary bee Osmia lignaria winters as a pre-emergent adult, and requires a period of cold temperature for winter diapause completion. It is a univoltine species, and diapause induction does not depend on photoperiod. To understand the potential effects of longer summers on O. lignaria populations, we exposed individuals to three treatments simulating early, mid and late winter arrivals, and measured respiration rates, metabolic expenditure, weight loss, fat body depletion, lipid levels and winter mortality. The early-winter treatment disrupted diapause development, but had no apparent negative effects on fitness. In contrast, late-winter bees had a greater energetic expenditure (1.5-fold), weight (1.4-fold) and lipid (2-fold) loss, greater fat body depletion, and a 19% increase in mortality compared to mid-winter bees. We also monitored adult eclosion and arrival of winter temperatures under natural conditions in four years. We found a positive correlation between mean degree-day accumulation during pre-wintering (a measure of asynchrony between adult eclosion and winter arrival) and yearly winter mortality. Individually, bees experiencing greater degree-day accumulations exhibited reduced post-winter longevity. Timing of adult eclosion in O. lignaria is dependent on the duration of the prepupal period, which occurs in mid-summer, is also diapause-mediated, and is longer in populations from southerly latitudes. In a global warming scenario, we expect long summer diapause phenotypes to replace short summer diapause phenotypes, effectively maintaining short pre-wintering periods in spite of delayed winter arrivals.

  11. Variations in Regional Mean Daily Precipitation Extremes and Related Circulation Anomalies over Central China During Boreal Summer

    Institute of Scientific and Technical Information of China (English)

    柯丹; 管兆勇

    2014-01-01

    The variations of regional mean daily precipitation extreme (RMDPE) events in central China and associated circulation anomalies during June, July, and August (JJA) of 1961-2010 are investigated by using daily in-situ precipitation observations and the NCEP/NCAR reanalysis data. The precipitation data were collected at 239 state-level stations distributed throughout the provinces of Henan, Hubei, and Hunan. During 1961-2010, the 99th percentile threshold for RMDPE is 23.585 mm day-1. The number of RMDPE events varies on both interannual and interdecadal timescales, and increases significantly after the mid 1980s. The RMDPE events happen most frequently between late June and mid July, and are generally associated with anomalous baroclinic tropospheric circulations. The supply of moisture to the southern part of central China comes in a stepping way from the outer-region of an abnormal anticyclone over the Bay of Bengal and the South China Sea. Fluxes of wave activity generated over the northeastern Tibetan Plateau converge over central China, which favors the genesis and maintenance of wave disturbances over the region. RMDPE events typically occur in tandem with a strong heating gradient formed by net heating in central China and the large-scale net cooling in the surrounding area. The occurrence of RMDPE events over central China is tied to anomalous local cyclonic circulations, topographic forcing over the northeast Tibetan Plateau, and anomalous gradients of diabatic heating between central China and the surrounding areas.

  12. Simulation of the variability and extremes of daily rainfall during the Indian summer monsoon for present and future times in a global time-slice experiment

    Energy Technology Data Exchange (ETDEWEB)

    May, W. [Danish Meteorological Institute, Lyngbyvej 100, 2100 Copenhagen (Denmark)

    2004-03-01

    In this study the simulation of the variability and extremes of daily rainfall during the Indian summer monsoon for the present-day and the future climate is investigated. This is done on the basis of a global time-slice experiment (TSL) with the ECHAM4 atmospheric general circulation model (GCM) at a high horizontal resolution of T106. The first time-slice (period: 1970-1999) represents the present-day climate and the second (2060-2089) the future climate. Moreover, observational rainfall data from the Global Precipitation Climatology Project (GPCP, 1997-2002) and rainfall data from the ECMWF re-analysis (ERA, 1958-2001) are considered. ERA reveals serious deficiencies in its representation of the variability and extremes of daily rainfall during the Indian summer monsoon. These are mainly a severe overestimation of the frequency of wet days over the oceans and in the Himalayas, where also the rainfall intensity is overestimated. Further, ERA shows unrealistically heavy rainfall events over the tropical Indian Ocean. The ECHAM4 atmospheric GCM at a horizontal resolution of T106, on the other hand, simulates the variability and extremes of daily rainfall in good agreement with the observations. The only marked deficiencies are an underestimation of the rainfall intensity on the west coast of the Indian peninsula and in Bangladesh, an overestimation over the tropical Indian Ocean, due to an erroneous northwestward extension of the tropical convergence zone, and an overestimation of the frequency of wet days in Tibet. Further, heavy rainfall events are relatively strong in the centre of the Indian peninsula. For the future, TSL predicts large increases in the rainfall intensity over the tropical Indian Ocean as well as in northern Pakistan and northwest India, but decreases in southern Pakistan, in the centre of the Indian peninsula, and over the western part of the Bay of Bengal. The frequency of wet days is markedly increased over the tropical Indian Ocean and

  13. Climate Change: A New Metric to Measure Changes in the Frequency of Extreme Temperatures using Record Data

    Science.gov (United States)

    Munasinghe, L.; Jun, T.; Rind, D. H.

    2012-01-01

    Consensus on global warming is the result of multiple and varying lines of evidence, and one key ramification is the increase in frequency of extreme climate events including record high temperatures. Here we develop a metric- called "record equivalent draws" (RED)-based on record high (low) temperature observations, and show that changes in RED approximate changes in the likelihood of extreme high (low) temperatures. Since we also show that this metric is independent of the specifics of the underlying temperature distributions, RED estimates can be aggregated across different climates to provide a genuinely global assessment of climate change. Using data on monthly average temperatures across the global landmass we find that the frequency of extreme high temperatures increased 10-fold between the first three decades of the last century (1900-1929) and the most recent decade (1999-2008). A more disaggregated analysis shows that the increase in frequency of extreme high temperatures is greater in the tropics than in higher latitudes, a pattern that is not indicated by changes in mean temperature. Our RED estimates also suggest concurrent increases in the frequency of both extreme high and extreme low temperatures during 2002-2008, a period when we observe a plateauing of global mean temperature. Using daily extreme temperature observations, we find that the frequency of extreme high temperatures is greater in the daily minimum temperature time-series compared to the daily maximum temperature time-series. There is no such observable difference in the frequency of extreme low temperatures between the daily minimum and daily maximum.

  14. The evolution of temperature extremes in the Gaspé Peninsula, Quebec, Canada (1974-2013)

    Science.gov (United States)

    Fortin, Guillaume; Acquaotta, Fiorella; Fratianni, Simona

    2016-07-01

    The majority of natural hazards that affect Canadian territory are the result of extreme climate and weather conditions. Among these weather hazards, some can be calculated from the application of thresholds for minimum and maximum temperatures at a daily or monthly timescale. These thermal indices allowed the prediction of extreme conditions that may have an impact on the human population by affecting, for example, health, agriculture, and water resources. In this article, we discuss the methods used (RHtestsV4, SPLIDHOM, ClimPACT) then describe the steps followed to calculate the indices, including how we dealt with the problem of missing data and the necessity to identify a common methodology to analyze the time series. We also present possible solutions for ensuring the quality of meteorological data. We then present an overview of the results, namely the main trends and variability of extreme temperature for seven stations located in the Gaspé Peninsula from 1974 to 2013. Our results indicate some break points in time series and positive trends for most indices related to the rise of the temperatures but indicate a negative trend for the indices related to low temperatures for most stations during the study period.

  15. Spatiotemporal variations of extreme low temperature for emergency transport: a nationwide observational study

    Science.gov (United States)

    Onozuka, Daisuke; Hagihara, Akihito

    2016-12-01

    Although recent studies have investigated the effect of extreme heat on emergency transport, few have investigated the spatiotemporal variations of extreme low temperature for emergency transport on a national scale. Data pertaining to emergency ambulance transport and weather variation in the 47 prefectures of Japan between 2007 and 2010 were obtained. Nonlinear and delayed relationships between temperature and morbidity were assessed using a two-stage analysis. First, a Poisson regression analysis allowing for overdispersion in a distributed lag nonlinear model was used to estimate the prefecture-specific effects of temperature on morbidity. Second, a multivariate meta-analysis was applied to pool estimates on a national level. Of 15,868,086 emergency transports over the study period, 5,375,621 emergency transports were reported during the winter months (November through February). The overall cumulative relative risk (RR) at the first percentile vs. the minimum morbidity percentile was 1.24 (95 % CI = 1.15-1.34) for all causes, 1.50 (95 % CI = 1.30-1.74) for cardiovascular diseases, and 1.59 (95 % CI = 1.33-1.89) for respiratory diseases. There were differences in the temporal variations between extreme low temperature and respiratory disease morbidity. Spatial variation between prefectures was observed for all causes (Cochran Q test, p social and environmental factors, which can be responsible for spatial heterogeneity between prefectures.

  16. Time series requirements and trends of temperature and precipitation extremes over Italy

    Science.gov (United States)

    Fioravanti, Guido; Desiato, Franco; Fraschetti, Piero; Perconti, Walter; Piervitali, Emanuela

    2013-04-01

    Extreme climate events have strong impacts on society and economy; accordingly,the knowledge of their trends on long period is crucial for the definition and implementation of a national adaptation strategy to climate change. The Research Programme on Climate Variability and Predictability (CLIVAR) identified a set of temperature and precipitation indices suited to investigate variability and trends of climate extremes. It is well known that extreme indices calculation is more demanding than first and second order statistics are: daily temperature and precipitation data are required and strict constrains in terms of continuity and completeness must be met. In addition, possible dishomogeneities affecting time series must be identified and adjusted before indices calculation. When metadata are not available, statistical methods can provide scientist a relevant support for homogeneity check; however, ad-hoc decision criteria (sometimes subjective) must be applied whenever contradictory results characterize different statistical homogeneity tests. In this work, a set of daily (minimum and maximum) temperature and precipitation time series for the period 1961-2011 were selected in order to guarantee a quite uniform spatial distribution of the stations over the Italian territory and according to the afore-said continuity and completeness criteria. Following the method described by Vincent, the homogeneity check of temperature time series was run at annual level. Two well-documented tests were employed (F-test and T-test), both implemented in the free R-package RHtestV3. The Vincent method was also used for a further investigation of time series homogeneity. Temperature dishomogeneous series were discarded. For precipitation series, no homogeneity check was run. The selected series were employed at daily level to calculate a reliable set of extreme indices. For each station, a linear model was employed for indices trend estimation. Finally, single station results were

  17. Seasonal trends in precipitation and surface air temperature extremes in mainland Portugal, 1941-2007

    Science.gov (United States)

    de Lima, M. I. P.; Santo, F. E.; Ramos, A. M.

    2012-04-01

    Several climate models predict, on a global scale, modifications in climate variables that are expected to have impact on society and the environment. The concern is on changes in the variability of processes, the mean and extreme events (maximum and minimum). To explore recent changes in precipitation and near surface air temperature extremes in mainland Portugal, we have inspected trends in time series of specific indices defined for daily data. These indices were recommended by the Commission for Climatology/Climate Variability and Predictability (CCl/CLIVAR) Working Group on Climate Change Detection, and include threshold indices, probability indices, duration indices and other indices. The precipitation and air temperature data used in this study are from, respectively, 57 and 23 measuring stations scattered across mainland Portugal, and cover the periods 1941-2007, for precipitation, and 1941-2006, for temperature. The study focuses on changes at the seasonal scale. Strong seasonality is one of the main features of climate in mainland Portugal. Intensification of the seasonality signal across the territory, particularly in the more sensitive regions, might contribute to endanger already fragile soil and water resources and ecosystems, and the local environmental and economic sustainability. Thus, the understanding of variations in the intensity, frequency and duration of extreme precipitation and air temperature events at the intra-annual scale is particularly important in this geographical area. Trend analyses were conducted over the full period of the records and for sub-periods, exploring patterns of change. Results show, on the one hand, regional differences in the tendency observed in the time series analysed; and, on the other hand, that although trends in annual indices are in general not statistically significant, there are sometimes significant changes over time in the data at the seasonal scale that point out to an increase in the already existing

  18. Numerical simulation of extreme snowmelt observed at the SIGMA-A site, northwest Greenland, during summer 2012

    Directory of Open Access Journals (Sweden)

    M. Niwano

    2015-05-01

    Full Text Available The surface energy balance (SEB from 30 June to 14 July 2012 at site SIGMA (Snow Impurity and Glacial Microbe effects on abrupt warming in the Arctic-A, (78°03' N, 67°38' W; 1490 m a.s.l. on the northwest Greenland Ice Sheet (GrIS was investigated by using in situ atmospheric and snow measurements as well as numerical modeling with a one-dimensional multi-layered physical snowpack model called SMAP (Snow Metamorphism and Albedo Process. At SIGMA-A, remarkable near-surface snowmelt and continuous heavy rainfall (accumulated precipitation between 10 and 14 July was estimated to be 100 mm were observed after 10 July 2012. Application of the SMAP model to the GrIS snowpack was evaluated based on the snow temperature profile, snow surface temperature, surface snow grain size, and shortwave albedo, all of which the model simulated reasonably well. Above all, the fact that the SMAP model successfully reproduced frequently observed rapid increases in snow albedo under cloudy conditions highlights the advantage of the physically based snow albedo model (PBSAM incorporated in the SMAP model. Using such data and model, we estimated the SEB at SIGMA-A from 30 June to 14 July 2012. Radiation-related fluxes were obtained from in situ measurements, whereas other fluxes were calculated with the SMAP model. By examining the components of the SEB, we determined that low-level clouds accompanied by a significant temperature increase played an important role in the melt event observed at SIGMA-A. These conditions induced a remarkable surface heating via cloud radiative forcing in the polar region.

  19. Numerical simulation of extreme snow melt observed at the SIGMA-A site, northwest Greenland, during summer 2012

    Directory of Open Access Journals (Sweden)

    M. Niwano

    2015-01-01

    Full Text Available The surface energy balance (SEB from 30 June to 14 July 2012 at site SIGMA (Snow Impurity and Glacial Microbe effects on abrupt warming in the Arctic-A, (78°03' N, 67°38' W; 1490 m a.s.l. on the northwest Greenland Ice Sheet (GrIS was investigated by using in situ atmospheric and snow measurements, as well as numerical modeling with a one-dimensional, multi-layered, physical snowpack model called SMAP (Snow Metamorphism and Albedo Process. At SIGMA-A, remarkable near-surface snowmelt and continuous heavy rainfall (accumulated precipitation between 10 and 14 July was estimated to be 100 mm were observed after 10 July 2012. Application of the SMAP model to the GrIS snowpack was evaluated based on the snow temperature profile, snow surface temperature, surface snow grain size, and shortwave albedo, all of which the model simulated reasonably well. However, comparison of the SMAP-calculated surface snow grain size with in situ measurements during the period when surface hoar with small grain size was observed on-site revealed that it was necessary to input air temperature, relative humidity, and wind speed data from two heights to simulate the latent heat flux into the snow surface and subsequent surface hoar formation. The calculated latent heat flux was always directed away from the surface if data from only one height were input to the SMAP model, even if the value for roughness length of momentum was perturbed between the possible maximum and minimum values in numerical sensitivity tests. This result highlights the need to use two-level atmospheric profiles to obtain realistic latent heat flux. Using such profiles, we calculated the SEB at SIGMA-A from 30 June to 14 July 2012. Radiation-related fluxes were obtained from in situ measurements, whereas other fluxes were calculated with the SMAP model. By examining the components of the SEB, we determined that low-level clouds accompanied by a significant temperature increase played an important

  20. In situ observation and measurement of composites subjected to extremely high temperature

    Science.gov (United States)

    Fang, Xufei; Yu, Helong; Zhang, Guobing; Su, Hengqiang; Tang, Hongxiang; Feng, Xue

    2014-03-01

    In this work, we develop an instrument to study the ablation and oxidation process of materials such as C/SiC (carbon fiber reinforced silicon carbide composites) and ultra-high temperature ceramic in extremely high temperature environment. The instrument is integrated with high speed cameras with filtering lens, infrared thermometers and water vapor generator for image capture, temperature measurement, and humid atmosphere, respectively. The ablation process and thermal shock as well as the temperature on both sides of the specimen can be in situ monitored. The results show clearly the dynamic ablation and liquid oxide flowing. In addition, we develop an algorithm for the post-processing of the captured images to obtain the deformation of the specimens, in order to better understand the behavior of the specimen subjected to high temperature.

  1. Some traits of low temperature germplasm wheat under extremely unfavorable weather conditions

    Institute of Scientific and Technical Information of China (English)

    张嵩午; 王长发; 冯佰利; 苗芳; 周春菊; 张荣萍

    2001-01-01

    Through a long-term observation on the canopy temperature and some traits of wheat the temperature germplasm of wheat was found to result in the wheats having either a high or a low plant temperature. Under normal weather conditions, the wheat having a low temperature germplasm (LTG) demonstrated several advantageous physiologi-cal and agronomic traits than those having a high temperature germplasm (HTG). Under the extremely unfavorableweather conditions, such as rainy weather or severe drought, LTG wheat still could maintain its superiority to HTG wheat in physiological and agronomic traits including leaf functional duration, chlorophyll content, malondialdehyde content, transpiration rate, net photosynthesis rate, root vitality and kernel plumpness. The wide adaptability of LTG wheat to awide range of meteoro-ecological conditions could provide a valuable germplasm in breeding of good strains with broad-spectrum stress resistance.

  2. Solar Orbiter- Solar Array- Thermal Design for an Extreme Temperature Mission

    Science.gov (United States)

    Muller, Jens; Paarmann, Carola; Lindner, Anton; Kreutz, Martin; Oberhuttinger, Carola; Costello, Ian; Icardi, Lidia

    2014-08-01

    The Solar Orbiter mission is an interdisciplinary mission to the sun, carried out by ESA in collaboration with NASA. The spacecraft will approach the sun close to 0.28 AU. At this distance, the solar array has to be operated under high solar array inclination angles to limit the temperatures to a maximum qualification temperature of 200°C for the photo voltaic assembly (PVA). Nevertheless, extreme temperatures appear at specific locations of the solar array which require purpose-built temperature protection measures. A very specific thermal protection is needed to keep the PVA and its supporting structures within the qualified temperature range and simultaneously minimize the thermal flux into the spacecraft.This paper describes the Solar Orbiter solar array design in general and its specific thermal design in particular. It describes the interdisciplinary steps between thermal- and mechanical analysis as well as design engineering necessary to result to the different shielding methods.

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

    Science.gov (United States)

    Uttal, T.; Makshtas, A.

    2015-12-01

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

  4. Impact of Urban Heat Island Effect on High Temperature in Summer-A Case of Ji'ning City%城市热岛效应对夏季高温的影响--以济宁市为例

    Institute of Scientific and Technical Information of China (English)

    王晓默; 董宁; 杨何著; 李莉

    2013-01-01

    With the globle warming development and propulsion of urbanization , the urban high temperature disaster in summer is becoming evident.In this paper, taking Ji'ning City as an example, the high temperature characters in summer and impact of urban heat island effect on high temperature disaster were analyzed.The results showed that the high temperature in summer of Ji'ning had the characters of wide range , more days and evident difference in years and months, the strength of extreme high temperature events and urban heat island effect in Ji'ning had evident character of increase, the high temperature in Ji'ning was mainly affected by urban heat island effect on the day, which was mainly occured in late spring and early summer , and the effect was more than 10%.%随着全球变暖趋势的加剧以及城市化的快速推进,城市夏季高温的危害越来越受到人们的重视。分析了济宁夏季高温特征及其城市热岛效应对高温灾害的影响。结果表明:济宁夏季高温期日数多、范围广,年、月际变化特征明显;极端高温事件强度和城市热岛效应明显增强;济宁城市高温主要受白天热岛效应的影响,且影响主要集中于春末夏初,作用超过10%。

  5. 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 up date (P > 0.10) and higher summer Tmax even reduced greenness by 2.6% K(-1) (P < 0.05). The stimulating effects of increasing Tmin were likely caused by reduced low temperature constraints, and the apparent negative effects of higher Tmax on 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.

  6. Minimum extreme temperature in the gulf of mexico: is there a connection with solar activity?

    Science.gov (United States)

    Maravilla, D.; Mendoza, B.; Jauregui, E.

    Minimum extreme temperature ( MET) series from several meteorological stations of the Gulf of Mexico are spectrally analyzed using the Maximum Entrophy Method. We obtained periodicities similar to those found in the sunspot number, the magnetic solar cycle, comic ray fluxes and geomagnetic activity which are modulated by solar activity. We suggested that the solar signal is perhaps present in the MET record of this region of Mexico.

  7. Perception, Action, and Cognition of Football Referees in Extreme Temperatures: Impact on Decision Performance

    Directory of Open Access Journals (Sweden)

    Nadia Gaoua

    2017-08-01

    Full Text Available Different professional domains require high levels of physical performance alongside fast and accurate decision-making. Construction workers, police officers, firefighters, elite sports men and women, the military and emergency medical professionals are often exposed to hostile environments with limited options for behavioral coping strategies. In this (mini review we use football refereeing as an example to discuss the combined effect of intense physical activity and extreme temperatures on decision-making and suggest an explicative model. In professional football competitions can be played in temperatures ranging from -5°C in Norway to 30°C in Spain for example. Despite these conditions, the referee’s responsibility is to consistently apply the laws fairly and uniformly, and to ensure the rules are followed without waning or adversely influencing the competitiveness of the play. However, strenuous exercise in extreme environments imposes increased physiological and psychological stress that can affect decision-making. Therefore, the physical exertion required to follow the game and the thermal strain from the extreme temperatures may hinder the ability of referees to make fast and accurate decisions. Here, we review literature on the physical and cognitive requirements of football refereeing and how extreme temperatures may affect referees’ decisions. Research suggests that both hot and cold environments have a negative impact on decision-making but data specific to decision-making is still lacking. A theoretical model of decision-making under the constraint of intense physical activity and thermal stress is suggested. Future naturalistic studies are needed to validate this model and provide clear recommendations for mitigating strategies.

  8. Perception, Action, and Cognition of Football Referees in Extreme Temperatures: Impact on Decision Performance.

    Science.gov (United States)

    Gaoua, Nadia; de Oliveira, Rita F; Hunter, Steve

    2017-01-01

    Different professional domains require high levels of physical performance alongside fast and accurate decision-making. Construction workers, police officers, firefighters, elite sports men and women, the military and emergency medical professionals are often exposed to hostile environments with limited options for behavioral coping strategies. In this (mini) review we use football refereeing as an example to discuss the combined effect of intense physical activity and extreme temperatures on decision-making and suggest an explicative model. In professional football competitions can be played in temperatures ranging from -5°C in Norway to 30°C in Spain for example. Despite these conditions, the referee's responsibility is to consistently apply the laws fairly and uniformly, and to ensure the rules are followed without waning or adversely influencing the competitiveness of the play. However, strenuous exercise in extreme environments imposes increased physiological and psychological stress that can affect decision-making. Therefore, the physical exertion required to follow the game and the thermal strain from the extreme temperatures may hinder the ability of referees to make fast and accurate decisions. Here, we review literature on the physical and cognitive requirements of football refereeing and how extreme temperatures may affect referees' decisions. Research suggests that both hot and cold environments have a negative impact on decision-making but data specific to decision-making is still lacking. A theoretical model of decision-making under the constraint of intense physical activity and thermal stress is suggested. Future naturalistic studies are needed to validate this model and provide clear recommendations for mitigating strategies.

  9. 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

    2017-02-01

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

  10. Using Annual Data to Estimate the Public Health Impact of Extreme Temperatures.

    Science.gov (United States)

    Goggins, William B; Yang, Chunyuh; Hokama, Tomiko; Law, Lewis S K; Chan, Emily Y Y

    2015-07-01

    Short-term associations between both hot and cold ambient temperatures and higher mortality have been found worldwide. Few studies have examined these associations on longer time scales. Age-standardized mortality rates (ASMRs) were calculated for 1976-2012 for Hong Kong SAR, People's Republic of China, defining "annual" time periods in 2 ways: from May through April of the following year and from November through October. Annual frequency and severity of extreme temperatures were summarized by using a degree-days approach with extreme heat expressed as annual degree-days >29.3°C and cold as annual degree-days ASMR, with adjustment for long-term trends. Increases of 10 hot or 200 cold degree-days in an annual period, the approximate interquartile ranges for these variables, were significantly (all P's ≤ 0.011) associated with 1.9% or 3.1% increases, respectively, in the annual ASMR for the May-April analyses and with 2.2% or 2.8% increases, respectively, in the November-October analyses. Associations were stronger for noncancer and elderly mortality. Mortality increases associated with extreme temperature are not simply due to short-term forward displacement of deaths that would have occurred anyway within a few weeks.

  11. Extremes temperatures and enthalpy in Finland and Sweden in a changing climate

    Energy Technology Data Exchange (ETDEWEB)

    Venaelaeinen, A.; Saku, S.; Jylhae, K. (Finnish Meteorological Institute (Finland)); Nikulin, G.; Kjellstroem, E.; Baerring, L. (Swedish Meteorological Institute (Sweden))

    2009-06-15

    Though risks caused by harsh weather conditions are taken into account in the planning of nuclear power plants, some exceptional weather events or combination of different events may prevent normal power operation and simultaneously endanger safe shutdown of the plant. Extreme weather events could influence, for example, the external power grid connection, emergency diesel generators (blockage of air intakes), ventilation and cooling of electric and electronics equipment rooms and the seawater intake. Due to the influence of an intensified greenhouse effect the climate is changing rapidly during the coming decades and this change is expected to have an influence also on the occurrence of extreme weather events. In this report we have examined extreme temperatures. Enthalpy is a parameter that combines air temperature and air humidity and it is used in the design of air conditioning systems. Therefore, we have included also return levels of enthalpy in our analysis. The influence of climate change on extreme temperatures is analysed based on regional climate model simulations. The reoccurrence times of high temperatures combined with high air humidity was analysed based on measurements made at five Finnish and three Swedish meteorological stations. Based on the observational records we find the 10 year return level of daily maximum temperature to be around 32 deg. C and the 100 year return level around 35 deg. C. If we look the return levels of warm and humid conditions then for example in Helsinki the 10 year return level of one week mean temperature in case mean air humidity is above 80% is 20.1 deg. C. The 10 year return level of daily maximum enthalpy is around 60 kJ/kg and the 100 year return level almost 70 kJ/kg. According to the climate model simulations the largest increase of 50-year return level of daily maximum temperature is found in southern Sweden and south-western Finland. By the end of this century the increase can be 3-5 deg. C. The largest change

  12. Probing the local, electronic and magnetic structure of matter under extreme conditions of temperature and pressure

    DEFF Research Database (Denmark)

    Torchio, R.; Boccato, S.; Cerantola, V.;

    2016-01-01

    In this paper we present recent achievements in the field of investigation of the local, electronic and magnetic structure of the matter under extreme conditions of pressure and temperature. These results were obtained thanks to the coupling of a compact laser heating system to the energy......-dispersive XAS technique available on the ID24 beamline at the ESRF synchrotron. The examples chosen concern the melting and the liquid structure of 3d metals and alloys under high pressures (HPs) and the observation of temperature-induced spin crossover in FeCO3 at HP....

  13. Electron-ion temperature ratio estimations in the summer polar mesosphere when subject to HF radio wave heating

    Science.gov (United States)

    Pinedo, H.; La Hoz, C.; Havnes, O.; Rietveld, M.

    2014-10-01

    We have inferred the electron temperature enhancements above mesospheric altitudes under Polar Mesospheric Summer Echoes (PMSE) conditions when the ionosphere is exposed to artificial HF radio wave heating. The proposed method uses the dependence of the radar cross section on the electron-to-ion temperature ratio to infer the heating factor from incoherent scatter radar (ISR) power measurements above 90 km. Model heating temperatures match our ISR estimations between 90 and 130 km with 0.94 Pearson correlation index. The PMSE strength measured by the MORRO MST radar is about 50% weaker during the heater-on period when the modeled electron-to-ion mesospheric temperature is approximately 10 times greater than the unperturbed value. No PMSE weakening is found when the mesospheric temperature enhancement is by a factor of three or less. The PMSE weakening and its absence are consistent with the modeled mesospheric electron temperatures. This consistency supports to the proposed method for estimating mesospheric electron temperatures achieved by independent MST and ISR radar measurements.

  14. Spatiotemporal distribution characteristics and attribution of extreme regional low temperature event

    Institute of Scientific and Technical Information of China (English)

    封泰晨; 张珂铨; 苏海晶; 王晓娟; 龚志强; 张文煜

    2015-01-01

    Based on an objective identification technique for regional low temperature event (OITRLTE), the daily minimum temperature in China has been detected from 1960 to 2013. During this period, there were 60 regional extreme low temperature events (ERLTEs), which are included in the 690 regional low temperature events (RLTEs). The 60 ERLTEs are analyzed in this paper. The results show that in the last 50 years, the intensity of the ERLTEs has become weak;the number of lasted days has decreased;and, the affected area has become small. However, that situation has changed in this century. In terms of spatial distribution, the high intensity regions are mainly in Northern China while the high frequency regions concentrate in Central and Eastern China. According to the affected area of each event, the 60 ERLTEs are classified into six types. The atmospheric circulation background fields which correspond to these types are also analyzed. The results show that, influenced by stronger blocking highs of Ural and Lake Baikal, as well as stronger southward polar vortex and East Asia major trough at 500-hPa geopotential height, cold air from high latitudes is guided to move southward and abnormal northerly winds at 850 hPa makes the cold air blow into China along diverse paths, thereby forming different types of regional extreme low temperatures in winter.

  15. Operation of a Giant Magnetoresistive (GMR) Digital Isolator, Type IL510, Under Extreme Temperatures

    Science.gov (United States)

    Patterson, Richard; Hammoud, Ahmad; Panko, Scott

    2010-01-01

    A relatively new type of signal isolation based on Giant Magnetoresistive (GMR) technology was investigated for potential use in harsh temperature environments. Operational characteristics of the 2Mbps single channel, IL510-Series commercial-off-the-shelf (COTS) digital isolator chip was obtained under extreme temperature exposure and thermal cycling in the range of -190 C to +120 C. The isolator was evaluated in terms of its output signal delivery and stability, output rise (t(sub r)) and fall times (t(sub f)), and propagation delays at 50% level between input and output during low to high (t(sub PLH)) and high to low (t(sub PHL)) transitions. The device performed very well throughout the entire test temperature range as no significant changes occurred either in its function or in its output signal timing characteristics. The limited thermal cycling, which comprised of 12 cycles between -190 C and +120 C, also had no influence on its performance. In addition, the device packaging underwent no structural damage due to the extreme temperature exposure. These preliminary results indicate that this semiconductor chip has the potential for use in a temperature range that extends beyond its specified regime. Additional and more comprehensive testing, however, is required to establish its operation and reliability and to determine its suitability for long-term use in space exploration missions.

  16. Spectral photometry of extreme helium stars: Ultraviolet fluxes and effective temperature

    Science.gov (United States)

    Drilling, J. S.; Schoenberner, D.; Heber, U.; Lynas-Gray, A. E.

    1982-01-01

    Ultraviolet flux distributions are presented for the extremely helium rich stars BD +10 deg 2179, HD 124448, LSS 3378, BD -9 deg 4395, LSE 78, HD 160641, LSIV -1 deg 2, BD 1 deg 3438, HD 168476, MV Sgr, LS IV-14 deg 109 (CD -35 deg 11760), LSII +33 deg 5 and BD +1 deg 4381 (LSIV +2 deg 13) obtained with the International Ultraviolet Explorer (IUE). Broad band photometry and a newly computed grid of line blanketed model atmospheres were used to determine accurate angular diameters and total stellar fluxes. The resultant effective temperatures are in most cases in satisfactory agreement with those based on broad band photometry and/or high resolution spectroscopy in the visible. For two objects, LSII +33 deg 5 and LSE 78, disagreement was found between the IUE observations and broadband photometry: the colors predict temperatures around 20,000 K, whereas the UV spectra indicate much lower photospheric temperatures of 14,000 to 15,000 K. The new temperature scale for extreme helium stars extends to lower effective temperatures than that of Heber and Schoenberner (1981) and covers the range from 8,500 K to 32,000 K.

  17. Detection of Spatio-temporal variations of rainfall and temperature extremes over India

    Science.gov (United States)

    Hari, V.; Karmakar, S.; Ghosh, S.

    2012-12-01

    implemented. The results from this study exhibit the observable changes in the rainfall extreme events that occurred over India in past century. The country experienced large spatial heterogeneity of all the four rainfall variables, even in the meteorologically homogeneous regions. The correlation analyses show that the maximum grids are having positive correlation, however for the duration-frequency, a significant correlation is observed in few grids, with most of the grids showing no correlation. The spatial variation of RL shows spatial heterogeneity and trend analyses exhibit lack of uniformity throughout India. The change in RL shows significant positive change in mainly during past 50 years. The possible reason could be urbanization and change in climate variables. Hence for further investigation, this analysis will be associated with the temperature extremes data throughout India.

  18. Variability of temperature sensitivity of extreme precipitation from a regional-to-local impact scale perspective

    Science.gov (United States)

    Schroeer, K.; Kirchengast, G.

    2016-12-01

    Relating precipitation intensity to temperature is a popular approach to assess potential changes of extreme events in a warming climate. Potential increases in extreme rainfall induced hazards, such as flash flooding, serve as motivation. It has not been addressed whether the temperature-precipitation scaling approach is meaningful on a regional to local level, where the risk of climate and weather impact is dealt with. Substantial variability of temperature sensitivity of extreme precipitation has been found that results from differing methodological assumptions as well as from varying climatological settings of the study domains. Two aspects are consistently found: First, temperature sensitivities beyond the expected consistency with the Clausius-Clapeyron (CC) equation are a feature of short-duration, convective, sub-daily to sub-hourly high-percentile rainfall intensities at mid-latitudes. Second, exponential growth ceases or reverts at threshold temperatures that vary from region to region, as moisture supply becomes limited. Analyses of pooled data, or of single or dispersed stations over large areas make it difficult to estimate the consequences in terms of local climate risk. In this study we test the meaningfulness of the scaling approach from an impact scale perspective. Temperature sensitivities are assessed using quantile regression on hourly and sub-hourly precipitation data from 189 stations in the Austrian south-eastern Alpine region. The observed scaling rates vary substantially, but distinct regional and seasonal patterns emerge. High sensitivity exceeding CC-scaling is seen on the 10-minute scale more than on the hourly scale, in storms shorter than 2 hours duration, and in shoulder seasons, but it is not necessarily a significant feature of the extremes. To be impact relevant, change rates need to be linked to absolute rainfall amounts. We show that high scaling rates occur in lower temperature conditions and thus have smaller effect on absolute

  19. The influence of winter and summer atmospheric circulation on the variability of temperature and sea ice around Greenland

    Directory of Open Access Journals (Sweden)

    Masayo Ogi

    2016-10-01

    Greenland is similar to the pattern of the SIEs in the Greenland Sea and Kara-Barents Seas. During summer, the T2m anomalies associated with all GrSTs and SIEs have positive anomalies over mid-latitudes. The two times series of all GrSTs and SIEs fluctuate quickly and display large trends towards warming temperatures and decreasing SIE. The summer SLP associated with all GrSTs and SIEs are characterised by a seesaw pattern between positive anomalies over the Arctic and negative anomalies over mid-latitudes. The summer SLP anomalies are similar to the summer AO pattern, and it is noteworthy that the summer anticyclonic circulation over the Arctic and Greenland has contributed to the variability and trends in both summer GrSTs and SIEs.

  20. 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.

  1. Effects of temperature and copper pollution on soil community--extreme temperature events can lead to community extinction.

    Science.gov (United States)

    Menezes-Oliveira, Vanessa B; Scott-Fordsmand, Janeck J; Soares, Amadeu M V M; Amorim, Monica J B

    2013-12-01

    Global warming affects ecosystems and species' diversity. The physiology of individual species is highly influenced by changes in temperature. The effects on species communities are less studied; they are virtually unknown when combining effects of pollution and temperature. To assess the effects of temperature and pollution in the soil community, a 2-factorial soil mesocosms multispecies experiment was performed. Three exposure periods (28 d, 61 d, and 84 d) and 4 temperatures (19 °C, 23 °C, 26 °C, and 29 °C) were tested, resembling the mean annual values for southern Europe countries and extreme events. The soil used was from a field site, clean, or spiked with Cu (100 mg Cu/kg). Results showed clear differences between 29 °C treatment and all other temperature treatments, with a decrease in overall abundance of organisms, further potentiated by the increase in exposure time. Folsomia candida was the most abundant species and Enchytraeus crypticus was the most sensitive to Cu toxicity. Differences in species optimum temperatures were adequately covered: 19 °C for Hypoaspis aculeifer or 26 °C for E. crypticus. The temperature effects were more pronounced the longer the exposure time. Feeding activity decreased with higher temperature and exposure time, following the decrease in invertebrate abundance, whereas for the same conditions the organic matter turnover increased. Hence, negative impacts on ecosystem services because of temperature increase can be expected by changes on soil function and as consequence of biodiversity loss. © 2013 SETAC.

  2. Ignition and combustion of pyrotechnics at low pressures and at temperature extremes

    Directory of Open Access Journals (Sweden)

    Clive Woodley

    2017-06-01

    Full Text Available Rapid and effective ignition of pyrotechnic countermeasure decoy flares is vitally important to the safety of expensive military platforms such as aircraft. QinetiQ is conducting experimental and theoretical research into pyrotechnic countermeasure decoy flares. A key part of this work is the development and application of improved models to increase the understanding of the ignition processes occurring for these flares. These models have been implemented in a two-dimensional computational model and details are described in this paper. Previous work has conducted experiments and validated the computational model at ambient temperature and pressure. More recently the computational model has been validated at pressures down to that equivalent to 40,000 feet but at ambient temperature (∼290 K. This paper describes further experimental work in which the ignition delays of the priming material in inert countermeasure decoy flares were determined for pressures down to 40,000 feet and at temperature extremes of −40 °C and 100 °C. Also included in this paper is a comparison of the measured and predicted ignition delays at low pressures and temperature extremes. The agreement between the predicted and measured ignition delays is acceptable.

  3. Experimental modeling of the influence of the rise in average summer temperatures on carbon circulation in tundra ecosystems

    Science.gov (United States)

    Barkhatov, Yu. V.; Tikhomirov, A. A.; Ushakova, S. A.; Shikhov, V. N.; Bartsev, S. I.; Degermendzhi, A. G.

    2016-11-01

    A sealed vegetation chamber was designed and constructed for physical simulation of climate conditions in the Subarctic zone during the spring-summer time. The small laboratory tundra-simulating ecosystem (TSE) was created for comparative evaluation of the rates of soil respiration and of the total balance of carbon fluxes in tundra ecosystems. The test experiment was performed to study the TSE response to a temperature rise in air and soil by 2°C in terms of the intensity of the CO2 flux. It was shown that this increase in temperature would cause a pronounced shift in the balance of CO2 production and utilization in the ecosystem from near-zero values to a stable generation of 24 μmol/h of CO2 per 1 kg of dry biomass.

  4. Elucidating the impact of temperature variability and extremes on cereal croplands through remote sensing.

    Science.gov (United States)

    Duncan, John M A; Dash, Jadunandan; Atkinson, Peter M

    2015-04-01

    Remote sensing-derived wheat crop yield-climate models were developed to highlight the impact of temperature variation during thermo-sensitive periods (anthesis and grain-filling; TSP) of wheat crop development. Specific questions addressed are: can the impact of temperature variation occurring during the TSP on wheat crop yield be detected using remote sensing data and what is the impact? Do crop critical temperature thresholds during TSP exist in real world cropping landscapes? These questions are tested in one of the world's major wheat breadbaskets of Punjab and Haryana, north-west India. Warming average minimum temperatures during the TSP had a greater negative impact on wheat crop yield than warming maximum temperatures. Warming minimum and maximum temperatures during the TSP explain a greater amount of variation in wheat crop yield than average growing season temperature. In complex real world cereal croplands there was a variable yield response to critical temperature threshold exceedance, specifically a more pronounced negative impact on wheat yield with increased warming events above 35 °C. The negative impact of warming increases with a later start-of-season suggesting earlier sowing can reduce wheat crop exposure harmful temperatures. However, even earlier sown wheat experienced temperature-induced yield losses, which, when viewed in the context of projected warming up to 2100 indicates adaptive responses should focus on increasing wheat tolerance to heat. This study shows it is possible to capture the impacts of temperature variation during the TSP on wheat crop yield in real world cropping landscapes using remote sensing data; this has important implications for monitoring the impact of climate change, variation and heat extremes on wheat croplands. © 2014 John Wiley & Sons Ltd.

  5. Associating emergency room visits with first and prolonged extreme temperature event in Taiwan: A population-based cohort study.

    Science.gov (United States)

    Wang, Yu-Chun; Lin, Yu-Kai; Chuang, Chun-Yu; Li, Ming-Hsu; Chou, Chang-Hung; Liao, Chun-Hui; Sung, Fung-Chang

    2012-02-01

    The present study evaluated emergency room visit (ERV) risks for all causes and cardiopulmonary diseases associated with temperature and long-lasting extreme temperatures from 2000 to 2009 in four major cities in Taiwan. The city-specific daily average temperatures at the high 95th, 97th, and 99th percentiles, and the low 10th, 5th, and 1st percentiles were defined as extreme heat and cold. A distributed lag non-linear model was used to estimate the cumulative relative risk (RR) of ERV for morbidities associated with temperatures (0 to 3-day lags), extreme heat and cold lasting for 2 to 9 days or longer, and with the annual first extreme heat or cold event after controlling for covariates. Low temperatures were associated with slightly higher ERV risks than high temperatures for circulatory diseases. After accounting for 4-day cumulative temperature effect, the ERV risks for all causes and respiratory diseases were found to be associated with extreme cold at the 5th percentile lasting for >8 days and 1st percentile lasting for >3 days. The annual first extreme cold event of 5th percentile or lower temperatures was also significantly associated with ERV, with RRs ranging from 1.09 to 1.12 for all causes and from 1.15 to 1.26 for respiratory diseases. The annual first extreme heat event of 99th percentile temperature was associated with higher ERV for all causes and circulatory diseases. Annual first extreme temperature event and intensified prolonged extreme cold events are associated with increased ERVs in Taiwan.

  6. Packhouse to port: Investigating temperature breaks in the South African summer fruit export cold chain

    CSIR Research Space (South Africa)

    Freiboth, H

    2014-10-01

    Full Text Available in refrigerated containers, as it moves from the pack house through the cold storage and transport segments towards the port of export. Historic temperature data collected with temperature monitoring devices from different fruit export supply chains of apples...

  7. Teleconnection, Regime Shift, and Predictability of Climate Extremes: A Case Study for the Russian Heat Wave and Pakistan Flood in Summer 2010

    Science.gov (United States)

    Lau, W. K.; Reale, O.; Kim, K.

    2011-01-01

    In this talk, we present observational evidence showing that the two major extremes events of the summer of 2010, i.e., the Russian heat wave and the Pakistan flood were physically connected. We find that the Pakistan flood was contributed by a series of unusually heavy rain events over the upper Indus River Basin in July-August. The rainfall regimes shifted from an episodic heavy rain regime in mid-to-late July to a steady heavy rain regime in August. An atmospheric Rossby wave associated with the development of the Russian heat wave was instrumental in spurring the episodic rain events , drawing moisture from the Bay of Bengal and the northern Arabian Sea. The steady rain regime was maintained primarily by monsoon moisture surges from the deep tropics. From experiments with the GEOS-5 forecast system, we assess the predictability of the heavy rain events associated with the Pakistan flood. Preliminary results indicate that there are significantly higher skills in the rainfall forecasts during the episodic heavy rain events in July, compared to the steady rain period in early to mid-August. The change in rainfall predictability may be related to scale interactions between the extratropics and the tropics resulting in a modulation of rainfall predictability by the circulation regimes.

  8. Teleconnection, regime shift, and predictability of climate extremes: A case study for the Russian heat wave and Pakistan flood in summer 2010.

    Science.gov (United States)

    Lau, W. K.; Reale, O.; Kim, K.

    2011-12-01

    In this talk, we present observational evidence showing that the two major extremes events of the summer of 2010, i.e., the Russian heat wave and the Pakistan flood were physically connected. We find that the Pakistan flood was contributed by a series of unusually heavy rain events over the upper Indus River Basin in July-August. The rainfall regimes shifted from an episodic heavy rain regime in mid-to-late July to a steady heavy rain regime in August. An atmospheric Rossby wave associated with the development of the Russian heat wave was instrumental in spurring the episodic rain events , drawing moisture from the Bay of Bengal and the northern Arabian Sea. The steady rain regime was maintained primarily by monsoon moisture surges from the deep tropics. From experiments with the GEOS-5 forecast system, we assess the predictability of the heavy rain events associated with the Pakistan flood. Preliminary results indicate that there are significantly higher skills in the rainfall forecasts during the episodic heavy rain events in July, compared to the steady rain period in early to mid-August. The change in rainfall predictability may be related to scale interactions between the extratropics and the tropics, resulting in a modulation of rainfall predictability by the circulation regimes.

  9. Characterizing the effect of summer temperature on heatstroke-related emergency ambulance dispatches in the Kanto area of Japan

    Science.gov (United States)

    Ng, Chris Fook Sheng; Ueda, Kayo; Ono, Masaji; Nitta, Hiroshi; Takami, Akinori

    2014-07-01

    Despite rising concern on the impact of heat on human health, the risk of high summer temperature on heatstroke-related emergency dispatches is not well understood in Japan. A time-series study was conducted to examine the association between apparent temperature and daily heatstroke-related ambulance dispatches (HSAD) within the Kanto area of Japan. A total of 12,907 HSAD occurring from 2000 to 2009 in five major cities—Saitama, Chiba, Tokyo, Kawasaki, and Yokohama—were analyzed. Generalized additive models and zero-inflated Poisson regressions were used to estimate the effects of daily maximum three-hour apparent temperature (AT) on dispatch frequency from May to September, with adjustment for seasonality, long-term trend, weekends, and public holidays. Linear and non-linear exposure effects were considered. Effects on days when AT first exceeded its summer median were also investigated. City-specific estimates were combined using random effects meta-analyses. Exposure-response relationship was found to be fairly linear. Significant risk increase began from 21 °C with a combined relative risk (RR) of 1.22 (95 % confidence interval, 1.03-1.44), increasing to 1.49 (1.42-1.57) at peak AT. When linear exposure was assumed, combined RR was 1.43 (1.37-1.50) per degree Celsius increment. Overall association was significant the first few times when median AT was initially exceeded in a particular warm season. More than two-thirds of these initial hot days were in June, implying the harmful effect of initial warming as the season changed. Risk increase that began early at the fairly mild perceived temperature implies the need for early precaution.

  10. Equation of state density models for hydrocarbons in ultradeep reservoirs at extreme temperature and pressure conditions

    Science.gov (United States)

    Wu, Yue; Bamgbade, Babatunde A.; Burgess, Ward A.; Tapriyal, Deepak; Baled, Hseen O.; Enick, Robert M.; McHugh, Mark A.

    2013-10-01

    The necessity of exploring ultradeep reservoirs requires the accurate prediction of hydrocarbon density data at extreme temperatures and pressures. In this study, three equations of state (EoS) models, Peng-Robinson (PR), high-temperature high-pressure volume-translated PR (HTHP VT-PR), and perturbed-chain statistical associating fluid theory (PC-SAFT) EoS are used to predict the density data for hydrocarbons in ultradeep reservoirs at temperatures to 523 K and pressures to 275 MPa. The calculated values are compared with experimental data. The results show that the HTHP VT-PR EoS and PC-SAFT EoS always perform better than the regular PR EoS for all the investigated hydrocarbons.

  11. Composite Materials under Extreme Radiation and Temperature Environments of the Next Generation Nuclear Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Simos, N.

    2011-05-01

    In the nuclear energy renaissance, driven by fission reactor concepts utilizing very high temperatures and fast neutron spectra, materials with enhanced performance that exceeds are expected to play a central role. With the operating temperatures of the Generation III reactors bringing the classical reactor materials close to their performance limits there is an urgent need to develop and qualify new alloys and composites. Efforts have been focused on the intricate relations and the high demands placed on materials at the anticipated extreme states within the next generation fusion and fission reactors which combine high radiation fluxes, elevated temperatures and aggressive environments. While nuclear reactors have been in operation for several decades, the structural materials associated with the next generation options need to endure much higher temperatures (1200 C), higher neutron doses (tens of displacements per atom, dpa), and extremely corrosive environments, which are beyond the experience on materials accumulated to-date. The most important consideration is the performance and reliability of structural materials for both in-core and out-of-core functions. While there exists a great body of nuclear materials research and operating experience/performance from fission reactors where epithermal and thermal neutrons interact with materials and alter their physio-mechanical properties, a process that is well understood by now, there are no operating or even experimental facilities that will facilitate the extreme conditions of flux and temperature anticipated and thus provide insights into the behaviour of these well understood materials. Materials, however, still need to be developed and their interaction and damage potential or lifetime to be quantified for the next generation nuclear energy. Based on material development advances, composites, and in particular ceramic composites, seem to inherently possess properties suitable for key functions within the

  12. Part 2. Association of daily mortality with ambient air pollution, and effect modification by extremely high temperature in Wuhan, China.

    Science.gov (United States)

    Qian, Zhengmin; He, Qingci; Lin, Hung-Mo; Kong, Lingli; Zhou, Dunjin; Liang, Shengwen; Zhu, Zhichao; Liao, Duanping; Liu, Wenshan; Bentley, Christy M; Dan, Jijun; Wang, Beiwei; Yang, Niannian; Xu, Shuangqing; Gong, Jie; Wei, Hongming; Sun, Huilin; Qin, Zudian

    2010-11-01

    Fewer studies have been published on the association between daily mortality and ambient air pollution in Asia than in the United States and Europe. This study was undertaken in Wuhan, China, to investigate the acute effects of air pollution on mortality with an emphasis on particulate matter (PM*). There were three primary aims: (1) to examine the associations of daily mortality due to all natural causes and daily cause-specific mortality (cardiovascular [CVD], stroke, cardiac [CARD], respiratory [RD], cardiopulmonary [CP], and non-cardiopulmonary [non-CP] causes) with daily mean concentrations (microg/m3) of PM with an aerodynamic diameter--10 pm (PM10), sulfur dioxide (SO2), nitrogen dioxide (NO2), or ozone (O3); (2) to investigate the effect modification of extremely high temperature on the association between air pollution and daily mortality due to all natural causes and daily cause-specific mortality; and (3) to assess the uncertainty of effect estimates caused by the change in International Classification of Disease (ICD) coding of mortality data from Revision 9 (ICD-9) to Revision 10 (ICD-10) code. Wuhan is called an "oven city" in China because of its extremely hot summers (the average daily temperature in July is 37.2 degrees C and maximum daily temperature often exceeds 40 degrees C). Approximately 4.5 million residents live in the core city area of 201 km2, where air pollution levels are higher and ranges are wider than the levels in most cities studied in the published literature. We obtained daily mean levels of PM10, SO2, and NO2 concentrations from five fixed-site air monitoring stations operated by the Wuhan Environmental Monitoring Center (WEMC). O3 data were obtained from two stations, and 8-hour averages, from 10:00 to 18:00, were used. Daily mortality data were obtained from the Wuhan Centres for Disease Prevention and Control (WCDC) during the study period of July 1, 2000, to June 30, 2004. To achieve the first aim, we used a regression of

  13. Assessment of SOI AND Gate, Type CHT-7408, for Operation in Extreme Temperature Environments

    Science.gov (United States)

    Patterson, Richard; Hammoud, Ahmad; Dones, Keishla Rivera

    2009-01-01

    Electronic parts based on silicon-on-insulator (SOI) technology are finding widespread applications due to their ability to operate in harsh environments and the benefits they offer as compared to their silicon counterparts. Due to their construction, they are tailored for high temperature operation and show good tolerance to radiation events. In addition, their inherent design lessens the formation of parasitic junctions, thereby reducing leakage currents, decreasing power consumption, and enhancing speed. These devices are typically rated in temperature capability from -55 C to about +225 C, and their characteristics over this temperature range are documented in data sheets. Since electronics in some of NASA space exploration missions are required to operate under extreme temperature conditions, both cold and hot, their characteristic behavior within the full temperature spectrum must be determined to establish suitability for use in space applications. The effects of extreme temperature exposure on the performance of a new commercial-off-the-shelf (COTS) SOI AND gate device were evaluated in this work. The high temperature, quad 2-inputs AND gate device, which was recently introduced by CISSOID, is fabricated using a CMOS SOI process. Some of the specifications of the CHT-7408 chip are listed in a table. By supplying a constant DC voltage to one gate input and a 10 kHz square wave into the other associated gate input, the chip was evaluated in terms of output response, output rise (t(sub r)) and fall times (tf), and propagation delays (using a 50% level between input and output during low to high (tPLH) and high to low (tPHL) transitions). The supply current of the gate circuit was also obtained. These parameters were recorded at various test temperatures between -195 C and +250 C using a Sun Systems environmental chamber programmed at a temperature rate of change of 10 C/min. In addition, the effects of thermal cycling on this chip were determined by exposing

  14. Assessing the impact of extreme air temperature on fruit trees by modeling weather dependent phenology with variety-specific thermal requirements

    Science.gov (United States)

    Alfieri, Silvia Maria; De Lorenzi, Francesca; Missere, Daniele; Buscaroli, Claudio; Menenti, Massimo

    2013-04-01

    Extremely high and extremely low temperature may have a terminal impact on the productivity of fruit tree if occurring at critical phases of development. Notorious examples are frost during flowering or extremely high temperature during fruit setting. The dates of occurrence of such critical phenological stages depend on the weather history from the start of the yearly development cycle in late autumn, thus the impact of climate extremes can only be evaluated correctly if the phenological development is modeled taking into account the weather history of the specific year being evaluated. Climate change impact may lead to a shift in timing of phenological stages and change in the duration of vegetative and reproductive phases. A changing climate can also exhibit a greater climatic variability producing quite large changes in the frequency of extreme climatic events. We propose a two-stage approach to evaluate the impact of predicted future climate on the productivity of fruit trees. The phenological development is modeled using phase - specific thermal times and variety specific thermal requirements for several cultivars of pear, apricot and peach. These requirements were estimated using phenological observations over several years in Emilia Romagna region and scientific literature. We calculated the dates of start and end of rest completion, bud swell, flowering, fruit setting and ripening stages , from late autumn through late summer. Then phase-specific minimum and maximum cardinal temperature were evaluated for present and future climate to estimate how frequently they occur during any critically sensitive phenological phase. This analysis has been done for past climate (1961 - 1990) and fifty realizations of a year representative of future climate (2021 - 2050). A delay in rest completion of about 10-20 days has been predicted for future climate for most of the cultivars. On the other hand the predicted rise in air temperature causes an earlier development of

  15. Implications of dynamics underlying temperature and precipitation distributions for changes in extremes

    Science.gov (United States)

    Neelin, J. D.; Loikith, P. C.; Stechmann, S. N.; Sahany, S.; Bernstein, D. N.; Quinn, K. M.; Meyerson, J.; Hales, K.; Langenbrunner, B.

    2015-12-01

    Characterizing present-day probability distributions of temperature and precipitation measures are an important part of the pathway to improving quantitative assessment of changes in their extremes. In some cases, relatively simple prototypes for the dynamics underlying these distributions can assist in this characterization, pointing to key physical factors and measures to evaluate even in more complex distributions. In the case of daily temperature distributions, quantifying the widespread occurrence of non-Gaussian tails is motivated in part by tracer-advection across a maintained gradient prototypes. Substantial implications of the shape of these tails for regional changes in probabilities of temperature extremes with large-scale warming motivate measures of non-Gaussianity specific to this problem for assessing climate model present-day simulations. In the case of distributions of precipitation accumulations, simple prototypes yield insights into the form of the present-day distribution and predictions for the form of the global warming changes that can be evaluated in models and observations. Probability drops relatively slowly over a substantial range of accumulation size, followed by a key cutoff scale that limits large event probabilities in current climate but changes under global warming. Precipitation integrated over spatial clusters exhibits similar distribution features.

  16. Extremely Low Frequency Electromagnetic Field from Convective Air Warming System on Temperature Selection and Distance.

    Directory of Open Access Journals (Sweden)

    Kwang Rae Cho

    2014-12-01

    Full Text Available Hypothermia generates potentially severe complications in operating or recovery room. Forced air warmer is effective to maintain body temperature. Extremely low frequency electromagnetic field (ELF-EMF is harmful to human body and mainly produced by electronic equipment including convective air warming system. We investigated ELF-EMF from convective air warming device on various temperature selection and distance for guideline to protect medical personnel and patients.The intensity of ELF-EMF was measured as two-second interval for five minutes on various distance (0.1, 0.2, 0.3, 0.5 and 1meter and temperature selection (high, medium, low and ambient. All of electrical devices were off including lamp, computer and air conditioner. Groups were compared using one-way ANOVA. P<0.05 was considered significant.Mean values of ELF-EMF on the distance of 30 cm were 18.63, 18.44, 18.23 and 17.92 milligauss (mG respectively (high, medium, low and ambient temperature set. ELF-EMF of high temperature set was higher than data of medium, low and ambient set in all the distances.ELF-EMF from convective air warming system is higher in condition of more close location and higher temperature. ELF-EMF within thirty centimeters exceeds 2mG recommended by Swedish TCO guideline.

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

    Science.gov (United States)

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

    2013-05-01

    One of the main concerns of contemporary society regarding prevailing climate change is related to possible changes in the frequency and intensity of extreme events. Strong heat and cold waves, droughts, severe floods, and other climatic extremes have been of great interest to researchers because of its huge impact on the environment and population, causing high monetary damages and, in some cases, loss of life. The frequency and intensity of extreme events associated with precipitation and air temperature have been increased in several regions of the planet in recent years. These changes produce serious impacts on human activities such as agriculture, health, urban planning and development and management of water resources. In this paper, we analyze the trends in indices of climatic extremes related to daily precipitation and maximum and minimum temperatures at 22 meteorological stations of the National Institute of Meteorology (INMET) in Rio de Janeiro State (Brazil) in the last 50 years. The present trends are evaluated using the software RClimdex (Canadian Meteorological Service) and are also subjected to statistical tests. Preliminary results indicate that periods of drought are getting longer in Rio de Janeiro State, except in the North/Northwest area. In "Vale do Paraíba", "Região Serrana" and "Região dos Lagos" the increase of consecutive dry days is statistically significant. However, we also detected an increase in the total annual rainfall all over the State (taxes varying from +2 to +8 mm/year), which are statistically significant at "Região Serrana". Moreover, the intensity of heavy rainfall is also growing in most of Rio de Janeiro, except in "Costa Verde". The trends of heavy rainfall indices show significant increase in the "Metropolitan Region" and in "Região Serrana", factor that increases the vulnerability to natural disasters in these areas. With respect to temperature, it is found that the frequency of hot (cold) days and nights is

  18. Behavior of butachlor and pyrazosulfuron-ethyl in paddy water using micro paddy lysimeters under different temperature conditions in spring and summer.

    Science.gov (United States)

    Ok, Junghun; Doan, Nguyen Hai; Watanabe, Hirozumi; Thuyet, Dang Quoc; Boulange, Julien

    2012-08-01

    The behavior of butachlor and pyrazosulfuron-ethyl in paddy water was investigated using micro paddy lysimeters with prescribed hydrological conditions under ambient temperature in spring and summer for simulating two rice crop seasons. Although they were not significantly different, the dissipation of both herbicides in paddy water in the summer experiment was faster than in the spring experiment. The half-lives (DT(50)) in paddy water for spring and summer experiments were 3.2 and 2.5 days for butachlor, and 3.1 and 1.6 days for pyrazosulfuron-ethyl, respectively.

  19. Decadal co-variability of the summer surface air temperature and soil moisture in China under global warming

    Institute of Scientific and Technical Information of China (English)

    SU MingFeng; WANG HuiJun

    2007-01-01

    The self-calibrating Palmer Drought Severity Index (PDSI) is calculated using newly updated ground observations of monthly surface air temperature (SAT) and precipitation in China. The co-variabilities of PDSI and SAT are examined for summer for the period 1961-2004. The results show that there exist decadal climate co-variabilities and strong nonlinear interactions between SAT and soil moisture in many regions of China. Some of the co-variabilities can be linked to global warming. In summer, significant decadal co-variabilities from cool-wet to warm-dry conditions are found in the east region of Northwest China, North China, and Northeast China. An important finding is that in the west region of Northwest China and Southeast China, pronounced decadal co-variabilities take place from warm-dry to cool-wet conditions. Because significant warming was observed over most areas of the global land surface during the past 20-30 years, the shift to cool-wet conditions is a unique phenomenon which may deserve much scientific attention. The nonlinear interactions between SAT and soil moisture may partly account for the observed decadal co-variabilities. It is shown that anomalies of SAT will greatly affect the climatic co-variabilities, and changes of SAT may bring notable influence on the PDSI in China. These results provide observational evidence for increasing risks of decadal drought and wetness as anthropogenic global warming progresses.

  20. Reconstruction of full glacial environments and summer temperatures from Lago della Costa, a refugial site in Northern Italy

    Science.gov (United States)

    Samartin, Stéphanie; Heiri, Oliver; Kaltenrieder, Petra; Kühl, Norbert; Tinner, Willy

    2016-07-01

    Vegetation and climate during the last ice age and the Last Glacial Maximum (LGM, ∼23,000-19,000 cal BP) were considerably different than during the current interglacial (Holocene). Cold climatic conditions and growing ice-sheets during the last glaciation radically reduced forest extent in Europe to a restricted number of so-called "refugia", mostly located in the southern part of the continent. On the basis of paleobotanical analyses the Euganian Hills (Colli Euganei) in northeastern Italy have previously been proposed as one of the northernmost refugia of temperate trees (e.g. deciduous Quercus, Tilia, Ulmus, Fraxinus excelsior, Acer, Abies alba, Fagus sylvatica, Carpinus and Castanea) in Europe. In this study we provide the first quantitative, vegetation independent summer air temperature reconstruction for Northern Italy spanning the time ∼31,000-17,000 cal yr BP, which covers the coldest periods of the last glacial, including the LGM and Heinrich stadials 1 to 3. Chironomids preserved in a lake sediment core from Lago della Costa (7m a.s.l.), a small lake at the south-eastern edge of the Euganean Hills, allowed quantitative reconstruction of Full and Late Glacial summer air temperatures using a combined Swiss-Norwegian temperature inference model based on chironomid assemblages from 274 lakes. Chironomid and pollen evidence from Lago della Costa derives from finely stratified autochthonous organic gyttja sediments, which excludes major sediment mixing or reworking. After reconstructing paleo-temperatures, we address the question whether climate conditions were warm enough to permit the local survival of temperate tree species during the LGM and whether local expansions and pollen-inferred contractions of temperate tree taxa coincided with chironomid-inferred climatic changes. Our results suggest that chironomids at Lago della Costa have responded to major climatic fluctuations such as temperature decreases during the LGM and Heinrich stadials. The

  1. Comparing regional precipitation and temperature extremes in climate model and reanalysis products

    Directory of Open Access Journals (Sweden)

    Oliver Angélil

    2016-09-01

    Full Text Available A growing field of research aims to characterise the contribution of anthropogenic emissions to the likelihood of extreme weather and climate events. These analyses can be sensitive to the shapes of the tails of simulated distributions. If tails are found to be unrealistically short or long, the anthropogenic signal emerges more or less clearly, respectively, from the noise of possible weather. Here we compare the chance of daily land-surface precipitation and near-surface temperature extremes generated by three Atmospheric Global Climate Models typically used for event attribution, with distributions from six reanalysis products. The likelihoods of extremes are compared for area-averages over grid cell and regional sized spatial domains. Results suggest a bias favouring overly strong attribution estimates for hot and cold events over many regions of Africa and Australia, and a bias favouring overly weak attribution estimates over regions of North America and Asia. For rainfall, results are more sensitive to geographic location. Although the three models show similar results over many regions, they do disagree over others. Equally, results highlight the discrepancy amongst reanalyses products. This emphasises the importance of using multiple reanalysis and/or observation products, as well as multiple models in event attribution studies.

  2. Comparing regional precipitation and temperature extremes in climate model and reanalysis products.

    Science.gov (United States)

    Angélil, Oliver; Perkins-Kirkpatrick, Sarah; Alexander, Lisa V; Stone, Dáithí; Donat, Markus G; Wehner, Michael; Shiogama, Hideo; Ciavarella, Andrew; Christidis, Nikolaos

    2016-09-01

    A growing field of research aims to characterise the contribution of anthropogenic emissions to the likelihood of extreme weather and climate events. These analyses can be sensitive to the shapes of the tails of simulated distributions. If tails are found to be unrealistically short or long, the anthropogenic signal emerges more or less clearly, respectively, from the noise of possible weather. Here we compare the chance of daily land-surface precipitation and near-surface temperature extremes generated by three Atmospheric Global Climate Models typically used for event attribution, with distributions from six reanalysis products. The likelihoods of extremes are compared for area-averages over grid cell and regional sized spatial domains. Results suggest a bias favouring overly strong attribution estimates for hot and cold events over many regions of Africa and Australia, and a bias favouring overly weak attribution estimates over regions of North America and Asia. For rainfall, results are more sensitive to geographic location. Although the three models show similar results over many regions, they do disagree over others. Equally, results highlight the discrepancy amongst reanalyses products. This emphasises the importance of using multiple reanalysis and/or observation products, as well as multiple models in event attribution studies.

  3. SiC JFET Transistor Circuit Model for Extreme Temperature Range

    Science.gov (United States)

    Neudeck, Philip G.

    2008-01-01

    A technique for simulating extreme-temperature operation of integrated circuits that incorporate silicon carbide (SiC) junction field-effect transistors (JFETs) has been developed. The technique involves modification of NGSPICE, which is an open-source version of the popular Simulation Program with Integrated Circuit Emphasis (SPICE) general-purpose analog-integrated-circuit-simulating software. NGSPICE in its unmodified form is used for simulating and designing circuits made from silicon-based transistors that operate at or near room temperature. Two rapid modifications of NGSPICE source code enable SiC JFETs to be simulated to 500 C using the well-known Level 1 model for silicon metal oxide semiconductor field-effect transistors (MOSFETs). First, the default value of the MOSFET surface potential must be changed. In the unmodified source code, this parameter has a value of 0.6, which corresponds to slightly more than half the bandgap of silicon. In NGSPICE modified to simulate SiC JFETs, this parameter is changed to a value of 1.6, corresponding to slightly more than half the bandgap of SiC. The second modification consists of changing the temperature dependence of MOSFET transconductance and saturation parameters. The unmodified NGSPICE source code implements a T(sup -1.5) temperature dependence for these parameters. In order to mimic the temperature behavior of experimental SiC JFETs, a T(sup -1.3) temperature dependence must be implemented in the NGSPICE source code. Following these two simple modifications, the Level 1 MOSFET model of the NGSPICE circuit simulation program reasonably approximates the measured high-temperature behavior of experimental SiC JFETs properly operated with zero or reverse bias applied to the gate terminal. Modification of additional silicon parameters in the NGSPICE source code was not necessary to model experimental SiC JFET current-voltage performance across the entire temperature range from 25 to 500 C.

  4. Effect of extreme temperatures on battery charging and performance of electric vehicles

    Science.gov (United States)

    Lindgren, Juuso; Lund, Peter D.

    2016-10-01

    Extreme temperatures pose several limitations to electric vehicle (EV) performance and charging. To investigate these effects, we combine a hybrid artificial neural network-empirical Li-ion battery model with a lumped capacitance EV thermal model to study how temperature will affect the performance of an EV fleet. We find that at -10 °C, the self-weighted mean battery charging power (SWMCP) decreases by 15% compared to standard 20 °C temperature. Active battery thermal management (BTM) during parking can improve SWMCP for individual vehicles, especially if vehicles are charged both at home and at workplace; the median SWMCP is increased by over 30%. Efficiency (km/kWh) of the vehicle fleet is maximized when ambient temperature is close to 20 °C. At low (-10 °C) and high (+40 °C) ambient temperatures, cabin preconditioning and BTM during parking can improve the median efficiency by 8% and 9%, respectively. At -10 °C, preconditioning and BTM during parking can also improve the fleet SOC by 3-6%-units, but this also introduces a "base" load of around 140 W per vehicle. Finally, we observe that the utility of the fleet can be increased by 5%-units by adding 3.6 kW chargers to workplaces, but further improved charging infrastructure would bring little additional benefit.

  5. Experimental evidence of a stratospheric circulation influence on mesospheric temperatures and ice-particles during the 2010-2011 austral summer at 69°S

    Science.gov (United States)

    Morris, Ray J.; Höffner, Josef; Lübken, Franz-Josef; Viehl, Timo P.; Kaifler, Bernd; Klekociuk, Andrew R.

    2012-11-01

    A significant inter-annual decrease in polar mesosphere ice-particles, i.e., PMSE and PMC, during 2010-2011 is compared with earlier austral summers, in particular with 2009-2010. The first IAP iron lidar temperature measurement at Davis (68.6°S), Antarctica from 14 December 2010 are used to assess thermal effects of atmospheric processes on the mesopause region. We report low average temperatures of ˜125 K measured by Fe-lidar near 90 km when the PMSE season commenced, whereas temperatures were warmer in 2010-2011 compared to 2009-2010 at altitudes where PMSE normally occur (around 86 km). Summer mesopause region temperature anomalies are derived using Aura MLS records. We reveal that the late break-down of the Antarctic stratospheric polar vortex on 5 January 2010, coupled with enhanced early summer mesospheric zonal wind field, provide a barrier to upward propagation of atmospheric gravity waves to be the main mechanism for the observed warm early summer season below the mesopause. The mesopause in 2010-2011 was unusually high and cold. We conclude that the timing of the annual break-down of the southern polar stratospheric vortex as manifest in zonal winds at 30 hPa impacts mesosphere temperature and ice-particle formation early in the austral summer.

  6. Increase of record-breaking temperature and precipitation extremes in a warming world

    Science.gov (United States)

    Coumou, D.; Lehmann, J.; Robinson, A.; Rahmstorf, S.

    2011-12-01

    The last decade has seen many record-breaking weather events, including severe heat waves, as well as rainfall and drought extremes. At the same time, this decade was globally the warmest since accurate measurements started in the 19th century. This raises the question, often asked by public and media directly after the occurrence of a specific extreme, whether these extremes are related to global warming. Here we analyze record-breaking events in the last decade using global gridded datasets of monthly-mean surface temperature and precipitation. We compare the number of observed records with those expected in a stationary climate, for which the simple 1/n relationship holds, with n the number of previous data points (e.g. years). In addition, we develop a first-order theoretical model to quantify the respective contributions of climate change and natural variability to the occurrence of records. World wide the number of monthly heat records is now, on average 5 times larger than expected in a stationary climate. This indicates that record-breaking heat waves lasting for several weeks now have, on average, an 80% chance of being due to climatic warming. Some tropical regions including East-Africa, India and Amazonia have seen an even larger increase in the number of record breaking events, pushing the probability that a record event is due to climatic warming to more than 90%. The high number of observed records is well explained by a model assuming a linear warming over the last 40 years. Precipitation extremes are more complex than heat extremes as different physical processes associated with global warming are likely to affect them. Warmer air can hold more moisture and thus, in principle, enhances extremes in both rainfall maxima and minima. Also, changes in wind patterns will affect precipitation and it is expected that dry areas will become drier and wet areas wetter. We show that, globally averaged the number of observed records, both for minima and maxima

  7. Estimating the Effect of Climate Change on Crop Yields and Farmland Values: The Importance of Extreme Temperatures

    Science.gov (United States)

    This is a presentation titled Estimating the Effect of Climate Change on Crop Yields and Farmland Values: The Importance of Extreme Temperatures that was given for the National Center for Environmental Economics

  8. Quantitative summer and winter temperature reconstructions from pollen and chironomid data in the Baltic-Belarus area

    Science.gov (United States)

    Veski, Siim; Seppä, Heikki; Stančikaitė, Migle; Zernitskaya, Valentina; Reitalu, Triin; Gryguc, Gražyna; Heinsalu, Atko; Stivrins, Normunds; Amon, Leeli; Vassiljev, Jüri; Heiri, Oliver

    2015-04-01

    Quantitative reconstructions based on fossil pollen and chironomids are widely used and useful for long-term climate variability estimations. The Lateglacial and early Holocene period (15-8 ka BP) in the Baltic-Belarus (BB) area between 60°-51° N was characterized by sudden shifts in climate due to various climate forcings affecting the climate of the northern hemisphere and North Atlantic, including the proximity of receding ice sheets. Climate variations in BB during the LG were eminent as the southern part of the region was ice free during the Last Glacial Maximum over 19 ka BP, whereas northern Estonia became ice free no sooner than 13 ka BP. New pollen based reconstructions of summer (May-to-August) and winter (December-to-February) temperatures between 15-8 ka BP along a S-N transect in the BB area display trends in temporal and spatial changes in climate variability. These results are completed by two chironomid-based July mean temperature reconstructions (Heiri et al. 2014). The magnitude of change compared with modern temperatures was more prominent in the northern part of BB area than in the southern part. The 4 °C winter and 2 °C summer warming at the start of GI-1 was delayed in the BB area and Lateglacial maximum temperatures were reached at ca 13.6 ka BP, being 4 °C colder than the modern mean. The Younger Dryas cooling in the area was 5 °C colder than present as inferred by all proxies (Veski et al. in press). In addition, our analyses show an early Holocene divergence in winter temperature trends with modern values reaching 1 ka earlier (10 ka BP) in southern BB compared to the northern part of the region (9 ka BP). Heiri, O., Brooks, S.J., Renssen, H., Bedford, A., Hazekamp, M., Ilyashuk, B., Jeffers, E.S., Lang, B., Kirilova, E., Kuiper, S., Millet, L., Samartin, S., Toth, M., Verbruggen, F., Watson, J.E., van Asch, N., Lammertsma, E., Amon, L., Birks, H.H., Birks, J.B., Mortensen, M.F., Hoek, W.Z., Magyari, E., Muñoz Sobrino, C., Seppä, H

  9. In-Situ Acoustic Measurements of Temperature Profile in Extreme Environments

    Energy Technology Data Exchange (ETDEWEB)

    Skliar, Mikhail [Univ. of Utah, Salt Lake City, UT (United States)

    2015-03-31

    A gasifier’s temperature is the primary characteristic that must be monitored to ensure its performance and the longevity of its refractory. One of the key technological challenges impacting the reliability and economics of coal and biomass gasification is the lack of temperature sensors that are capable of providing accurate, reliable, and long-life performance in an extreme gasification environment. This research has proposed, demonstrated, and validated a novel approach that uses a noninvasive ultrasound method that provides real-time temperature distribution monitoring across the refractory, especially the hot face temperature of the refractory. The essential idea of the ultrasound measurements of segmental temperature distribution is to use an ultrasound propagation waveguide across a refractory that has been engineered to contain multiple internal partial reflectors at known locations. When an ultrasound excitation pulse is introduced on the cold side of the refractory, it will be partially reflected from each scatterer in the US propagation path in the refractory wall and returned to the receiver as a train of partial echoes. The temperature in the corresponding segment can be determined based on recorded ultrasonic waveform and experimentally defined relationship between the speed of sound and temperature. The ultrasound measurement method offers a powerful solution to provide continuous real time temperature monitoring for the occasions that conventional thermal, optical and other sensors are infeasible, such as the impossibility of insertion of temperature sensor, harsh environment, unavailable optical path, and more. Our developed ultrasound system consists of an ultrasound engineered waveguide, ultrasound transducer/receiver, and data acquisition, logging, interpretation, and online display system, which is simple to install on the existing units with minimal modification on the gasifier or use with new units. This system has been successfully tested

  10. Investigating temperature breaks in the summer fruit export cold chain: A case study

    Directory of Open Access Journals (Sweden)

    Heinri W. Freiboth

    2013-05-01

    Full Text Available There is concern in the South African fruit industry that a large amount of fruit and money is lost every season due to breaks in the fruit export cold chain. The possibility of a large percentage of losses in a significant sector of the economy warranted further investigation. This article attempted to highlight some of the possible problem areas in the cold chain, from the cold store to the port, by analysing historic temperature data from different fruit export supply chains of apples, pears and grapes. In addition, a trial shipment of apples was used to investigate temperature variation between different pallets in the same container. This research has added value to the South African fruit industry by identifying the need to improve operational procedures in the cold chain.

  11. Enhanced solar activity influence on the summer temperature variability of the southeast margin of the Qinghai-Tibetan Plateau in the late Holocene

    Science.gov (United States)

    Chang, Jie; Zhang, Enlou; Liu, Enfeng; Shulmeister, James

    2017-04-01

    We present two quantitative chironomid-based Holocene summer temperature records from the southeast margin of the Qinghai-Tibetan Plateau (QTP). The records are from two alpine lakes (Tiancai and Heihai) located at the elevation of close to 4000 m above sea level from Yunnan Province. The mean July temperatures were quantified by applying a transfer function model (r2 = 0.63, RMSEP = 2.3 °C) developed based on a 100-lake modern calibration dataset of south-west China. The results were validated using standard reconstruction diagnostics. Both records show that the total summer temperature variation is within 2.5 °C. The records also show that the overall pattern broadly matches the declining trend of the summer insolation at 30°N and the Asian Summer Monsoon records. The general declining trend is punctuated by a few warm and cool intervals on the centennial scale. We observed a periodicity pattern in the mean July temperature variability and these fluctuations are possibly related to both the solar irradiance and the summer monsoon changes. Solar activity may have played an enhanced role on the highland summer temperature changes in the late Holocene when the monsoon influence to south-western China is generally weakened. More comprehensive investigations are needed to clarify the relationship between solar activity, the East Asian and Indian Ocean summer monsoons and the response of alpine climate in order to disentangle these or the combined effects on the climate change in the broad region of south-western China.

  12. Future changes in extreme temperature events using the statistical downscaling model (SDSM in the trans-boundary region of the Jhelum river basin

    Directory of Open Access Journals (Sweden)

    Rashid Mahmood

    2014-10-01

    On the whole in the Jhelum basin, the intensity and frequency of warm temperature extremes are likely to be higher and the intensity and frequency of cold temperature extremes to be lower in the future.

  13. Future Changes Projections of Atmospheric Circulation and Precipitation and Temperature Patterns Over South America in Austral Summer

    Science.gov (United States)

    Shimizu, M. H.; Cavalcanti, I. F.

    2012-12-01

    Atmospheric circulation is primarily driven by temperature gradients across the globe due to differential heating of Earth's surface which leads to a surplus of energy in the tropics and a deficit in the high latitudes. However, due to global warming, changes in atmospheric circulation are expected, which could result in modifications also in precipitation pattern. There are some evidences of changes in atmospheric circulation, such as the expansion of tropical belt and the poleward shift of large-scale atmospheric circulation systems, such as jet streams. These changes can be enhanced in a scenario with increasing greenhouse gases concentration. The objective of this study was to analyze future changes of atmospheric circulation and precipitation and temperature patterns in the austral summer over South America under Representative Pathway Concentration 8.5 (RCP 8.5) emission scenario. This evaluation was made according to model projections based on the coordinated climate change experiments defined by Coupled Model Intercomparison Project phase 5 (CMIP5). Historical simulations were used to evaluate model performance in reproduce main climatic features over South America in the Austral Summer. This analysis showed that some models perform better than others, with a wide range of difference between simulations and Global Precipitation Climatology Project (GPCP) and European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-Interim data sets. In general, the models captured the main features of Austral Summer such as the northwest-southeast precipitation band associated with the South Atlantic Convergence Zone (SACZ) and the anticyclonic circulation at high levels related to Bolivian High. The projections from different models pointed out in general to a reduction of precipitation, however the signal was not the same over all the continent and for all models. For example, Met Office's HadGEM2-ES projection indicated a reduction of precipitation in most of

  14. The oxidation behavior of classical thermal barrier coatings exposed to extreme temperature

    Directory of Open Access Journals (Sweden)

    Alina DRAGOMIRESCU

    2017-03-01

    Full Text Available Thermal barrier coatings (TBC are designed to protect metal surfaces from extreme temperatures and improve their resistance to oxidation during service. Currently, the most commonly used systems are those that have the TBC structure bond coat (BC / top coat (TC layers. The top coat layer is a ceramic layer. Oxidation tests are designed to identify the dynamics of the thermally oxide layer (TGO growth at the interface of bond coat / top coat layers, delamination mechanism and the TBC structural changes induced by thermal conditions. This paper is a short study on the evolution of aluminum oxide protective layer along with prolonged exposure to the testing temperature. There have been tested rectangular specimens of metal super alloy with four surfaces coated with a duplex thermal barrier coating system. The specimens were microscopically and EDAX analyzed before and after the tests. In order to determine the oxide type, the samples were analyzed using X-ray diffraction. The results of the investigation are encouraging for future studies. The results show a direct relationship between the development of the oxide layer and long exposure to the test temperature. Future research will focus on changing the testing temperature to compare the results.

  15. Extreme Brightness Temperatures and Refractive Substructure in 3C273 with RadioAstron

    CERN Document Server

    Johnson, Michael D; Gwinn, Carl R; Gurvits, Leonid I; Narayan, Ramesh; Macquart, Jean-Pierre; Jauncey, David L; Voitsik, Peter A; Anderson, James M; Sokolovsky, Kirill V; Lisakov, Mikhail M

    2016-01-01

    Earth-space interferometry with RadioAstron provides the highest direct angular resolution ever achieved in astronomy at any wavelength. RadioAstron detections of the classic quasar 3C273 on interferometric baselines up to 171,000 km suggest brightness temperatures exceeding expected limits from the "inverse-Compton catastrophe" by two orders of magnitude. We show that at 18 cm, these estimates most probably arise from refractive substructure introduced by scattering in the interstellar medium. We use the scattering properties to estimate an intrinsic brightness temperature of 7*10^12 K, which is consistent with expected theoretical limits, but which is ~15 times lower than estimates that neglect substructure. At 6 cm, the substructure influences the measured values appreciably but gives an estimated brightness temperature that is comparable to models that do not account for the substructure. At 1.3 cm, the substructure does not affect the extremely high inferred brightness temperatures, in excess of 10^13 K....

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

    Science.gov (United States)

    Lorenz, Ruth; Argüeso, Daniel; Donat, Markus G.; Pitman, Andrew J.; Hurk, Bart; Berg, Alexis; Lawrence, David M.; Chéruy, Frédérique; Ducharne, Agnès.; Hagemann, Stefan; Meier, Arndt; Milly, P. 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. Manipulation of Samples at Extreme Temperatures for Fast in-situ Synchrotron Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Weber, Richard [Materials Development, Inc., Arlington Heights, IL (United States)

    2016-04-22

    An aerodynamic sample levitation system with laser beam heating was integrated with the APS beamlines 6 ID-D, 11 ID-C and 20 BM-B. The new capability enables in-situ measurements of structure and XANES at extreme temperatures (300-3500 °C) and in conditions that completely avoid contact with container surfaces. In addition to maintaining a high degree of sample purity, the use of aerodynamic levitation enables deep supercooling and greatly enhanced glass formation from a wide variety of melts and liquids. Development and integration of controlled extreme sample environments and new measurement techniques is an important aspect of beamline operations and user support. Processing and solidifying liquids is a critical value-adding step in manufacturing semiconductors, optical materials, metals and in the operation of many energy conversion devices. Understanding structural evolution is of fundamental importance in condensed materials, geology, and biology. The new capability provides unique possibilities for materials research and helps to develop and maintain a competitive materials manufacturing and energy utilization industry. Test samples were used to demonstrate key features of the capability including experiments on hot crystalline materials, liquids at temperatures from about 500 to 3500 °C. The use of controlled atmospheres using redox gas mixtures enabled in-situ changes in the oxidation states of cations in melts. Significant innovations in this work were: (i) Use of redox gas mixtures to adjust the oxidation state of cations in-situ (ii) Operation with a fully enclosed system suitable for work with nuclear fuel materials (iii) Making high quality high energy in-situ x-ray diffraction measurements (iv) Making high quality in-situ XANES measurements (v) Publishing high impact results (vi) Developing independent funding for the research on nuclear materials This SBIR project work led to a commercial instrument product for the niche market of processing and

  18. Characterizing the Chemical Stability of High Temperature Materials for Application in Extreme Environments

    Science.gov (United States)

    Opila, Elizabeth

    2005-01-01

    The chemical stability of high temperature materials must be known for use in the extreme environments of combustion applications. The characterization techniques available at NASA Glenn Research Center vary from fundamental thermodynamic property determination to material durability testing in actual engine environments. In this paper some of the unique techniques and facilities available at NASA Glenn will be reviewed. Multiple cell Knudsen effusion mass spectrometry is used to determine thermodynamic data by sampling gas species formed by reaction or equilibration in a Knudsen cell held in a vacuum. The transpiration technique can also be used to determine thermodynamic data of volatile species but at atmospheric pressures. Thermodynamic data in the Si-O-H(g) system were determined with this technique. Free Jet Sampling Mass Spectrometry can be used to study gas-solid interactions at a pressure of one atmosphere. Volatile Si(OH)4(g) was identified by this mass spectrometry technique. A High Pressure Burner Rig is used to expose high temperature materials in hydrocarbon-fueled combustion environments. Silicon carbide (SiC) volatility rates were measured in the burner rig as a function of total pressure, gas velocity and temperature. Finally, the Research Combustion Lab Rocket Test Cell is used to expose high temperature materials in hydrogen/oxygen rocket engine environments to assess material durability. SiC recession due to rocket engine exposures was measured as a function of oxidant/fuel ratio, temperature, and total pressure. The emphasis of the discussion for all techniques will be placed on experimental factors that must be controlled for accurate acquisition of results and reliable prediction of high temperature material chemical stability.

  19. Climate Characters of Summer Drought in Mountain City and the Effect on Flowers and Trees

    Institute of Scientific and Technical Information of China (English)

    Zhihui WANG; Jiaqi LI; Shuang ZHANG; Li JI; Dingxue ZHENG; Bin LIU

    2012-01-01

    [Objective] The aim was to provide references for development of industries engaging in flowers and trees in Beipei area in Chongqing. [Method] The occurring trend, intensity trend of summer drought, relationship of intensity with rainfall and extremely highest temperature, occurring trend during initial period of summer drought and the effects in mountain cities were analyzed, based on information on lasting period, rainfall, average temperature, extremely highest temperature of sum- mer drought in Beipei area in mountain cities during 1981-2010 and, growth condi- tion and phenological phenomena of Michelia champaca during 2005-2007. [Result] The occurring probability of summer drought in mountain cities was 57% and the probabilities of light, moderate, heavy and extreme drought were 30%, 10%, 7% and 10%; intensity of summer drought was none of linear relation with rainfall and ex- tremely highest temperature. In summer drought, daily average rainfall was less than 0.9 ram; extremely highest temperature was 35.0-45.0 ℃ with probability at 30%; initial period of summer drought was from later June to middle August and of extreme drought was later June-later July; the ending period was early September. During drought, when the extremely highest temperature (〉35.0 ℃) occurred in three days within a Hou, flowers and trees were affected by the hot drought and when the extreme temperature (〉40.0 ℃) occurred in three days within a Hou, the plants were seriously affected. [Conclusion] Based on characters of summer drought, pre- cautions can be taken to reduce effects of summer drought on flowers and trees with the help of weather forecast.

  20. Dynamical seasonal prediction of summer sea surface temperatures in the Great Barrier Reef

    Science.gov (United States)

    Spillman, C. M.; Alves, O.

    2009-03-01

    Coral bleaching is a serious problem threatening the world coral reef systems, triggered by high sea surface temperatures (SST) which are becoming more prevalent as a result of global warming. Seasonal forecasts from coupled ocean-atmosphere models can be used to predict anomalous SST months in advance. In this study, we assess the ability of the Australian Bureau of Meteorology seasonal forecast model (POAMA) to forecast SST anomalies in the Great Barrier Reef, Australia, with particular focus on the major 1998 and 2002 bleaching events. Advance warning of potential bleaching events allows for the implementation of management strategies to minimise reef damage. This study represents the first attempt to apply a dynamical seasonal model to the problem of coral bleaching and predict SST over a reef system for up to 6 months lead-time, a potentially invaluable tool for reef managers.

  1. Reconstruction of full glacial environments and summer air temperatures from Lago della Costa, a refugial site in northeastern Italy.

    Science.gov (United States)

    Samartin, S. V.; Heiri, O.; Boltshauser-Kaltenrieder, P.; Tinner, W.

    2014-12-01

    warming (ca. 14°C), conversely, the local contraction of these taxa between ca. 23'000-18'500 cal yr BP was possibly triggered by cooler summer air temperatures (ca. 13.4°C) and a significant moisture decline during the LGM.

  2. 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.)

  3. Biweekly Sea Surface Temperature over the South China Sea and its association with the Western North Pacific Summer Monsoon

    Science.gov (United States)

    Vaid, B. H.

    2017-02-01

    The association of the biweekly intraseasonal (BWI) oscillation in the Sea Surface Temperature (SST) over the South China Sea (SCS) and the Western North Pacific Summer Monsoon is authenticated using version 4 the Tropical Rainfall Measuring Mission Microwave Imager data (SST and rain) and heat fluxes from Ocean Atmosphere Flux project data during 1998-2012. The results suggest that the SCS involves ocean-atmosphere coupling on biweekly timescales. The positive biweekly SST anomalies lead the rain anomalies over the SCS by 3 days, with a significant correlation coefficient ( r = 0.6, at 99 % significance levels) between the SST-rain anomalies. It is evident from lead/lag correlation between biweekly SST and zonal wind shear that warm ocean surface induced by wind shear may contribute to a favorable condition of the convective activity over the SCS. The present study suggests that ocean-to-atmospheric processes induced by the BWI oscillation in the SCS SST results in enhanced sea level pressure and surface shortwave radiation flux during the summer monsoon. Besides, it is observed that the SCS BWI oscillation in the changes of SST causes a feedback in the atmosphere by modifying the atmospheric instability. This suggests that the active/break biweekly cycle of the SST over the SCS is related by sea level pressure, surface heat fluxes and atmospheric instability. The potential findings here indicate that the biweekly SST over the SCS play an important role in the eastward and the southward propagation of the biweekly anomalies in the Western North Pacific.

  4. A materials perspective on Li-ion batteries at extreme temperatures

    Science.gov (United States)

    Rodrigues, Marco-Tulio F.; Babu, Ganguli; Gullapalli, Hemtej; Kalaga, Kaushik; Sayed, Farheen N.; Kato, Keiko; Joyner, Jarin; Ajayan, Pulickel M.

    2017-08-01

    With the continuous upsurge in demand for energy storage, batteries are increasingly required to operate under extreme environmental conditions. Although they are at the technological forefront, Li-ion batteries have long been limited to room temperature, as internal phenomena during their operation cause thermal fluctuations. This has been the reason for many battery explosions in recent consumer products. While traditional efforts to address these issues focused on thermal management strategies, the performance and safety of Li-ion batteries at both low (60 °C) temperatures are inherently related to their respective components, such as electrode and electrolyte materials and the so-called solid-electrolyte interphases. This Review examines recent research that considers thermal tolerance of Li-ion batteries from a materials perspective, spanning a wide temperature spectrum (‑60 °C to 150 °C). The structural stability of promising cathodes, issues with anode passivation, and the competency of various electrolyte, binder and current collectors are compared for their thermal workability. The possibilities offered by each of these cell components could extend the environmental frontiers of commercial Li-ion batteries.

  5. Modified and double-clad large mode-area leakage channel fibers for extreme temperature conditions

    Science.gov (United States)

    Thavasi Raja, G.; Varshney, Shailendra K.

    2015-03-01

    Recently large-mode-area hybrid leakage channel fibers (HLCFs) were reported to overcome the limitation on mode area with single-mode (SM) operation for the practical bending radius of 7.5 cm at the preferred wavelength of 1064 nm. In this paper, we present the effects of a thermally induced refractive index change on the mode area of bend-compensated extremely LMA modified HLCFs (M-HLCFs) and double-clad M-HLCFs. A full-vectorial finite-element method-based modal solver is used to obtain the modal characteristics of M-HLCFs in various heat load conditions. Numerical simulations reveal that the effective mode area of M-HLCFs is ˜1433 μm2 at room temperature, which marginally decreases to ˜1387 μm2 while SM operation is maintained when the temperature distribution rises to ˜125 °C over the fiber geometry during high-power operations. We have also investigated a double-clad M-HLCF design exhibiting a mode area > ˜ 1000 μm2 for all heat load density variations up to a maximum of 12 × 109 W m-3, corresponding to a 250 °C temperature in the center of the fiber core region.

  6. Influences of summer water temperatures on the movement, distribution, and resources use of fluvial Westslope Cutthroat Trout in the South Fork Clearwater River basin

    Science.gov (United States)

    Dobos, Marika E.; Corsi, Matthew P.; Schill, Daniel J.; DuPont, Joseph M.; Quist, Michael

    2016-01-01

    Although many Westslope Cutthroat Trout Oncorhynchus clarkii lewisi populations in Idaho are robust and stable, population densities in some systems remain below management objectives. In many of those systems, such as in the South Fork Clearwater River (SFCR) system, environmental conditions (e.g., summer temperatures) are hypothesized to limit populations of Westslope Cutthroat Trout. Radiotelemetry and snorkeling methods were used to describe seasonal movement patterns, distribution, and habitat use of Westslope Cutthroat Trout in the SFCR during the summers of 2013 and 2014. Sixty-six radio transmitters were surgically implanted into Westslope Cutthroat Trout (170–405 mm TL) from May 30–June 25, 2013, and June 20–July 6, 2014. Sedentary and mobile summer movement patterns by Westslope Cutthroat Trout were observed in the SFCR. Westslope Cutthroat Trout were generally absent from the lower SFCR. In the upper region of the SFCR, fish generally moved from the main-stem SFCR into tributaries as water temperatures increased during the summer. Fish remained in the middle region of the SFCR where water temperatures were cooler than in the upper or lower regions of the SFCR. A spatially explicit water temperature model indicated that the upper and lower regions of the SFCR exceeded thermal tolerance levels of Westslope Cutthroat Trout throughout the summer. During snorkeling, 23 Westslope Cutthroat Trout were observed in 13 sites along the SFCR and at low density (mean ± SD, 0.0003 ± 0.0001 fish/m2). The distribution of fish observed during snorkeling was consistent with the distribution of radio-tagged fish in the SFCR during the summer. Anthropogenic activities (i.e., grazing, mining, road construction, and timber harvest) in the SFCR basin likely altered the natural flow dynamics and temperature regime and thereby limited stream habitat in the SFCR system for Westslope Cutthroat Trout.

  7. Low-pressure systems and extreme precipitation in central India: sensitivity to temperature changes

    Science.gov (United States)

    Sørland, Silje Lund; Sorteberg, Asgeir

    2016-07-01

    Extreme rainfall events in the central Indian region are often related to the passage of synoptic scale monsoon low-pressure systems (LPS). This study uses the surrogate climate change method on ten monsoon LPS cases connected to observed extreme rainfall events, to investigate how sensitive the precipitation and runoff are to an idealized warmer and moister atmosphere. The ten cases are simulated with three different initial and lateral boundary conditions: the unperturbed control run, and two sets of perturbed runs where the atmospheric temperature is increased uniformly throughout the atmosphere, the specific humidity increased according to Clausius Clapeyron's relation, but the large-scale flow is unchanged. The difference between the control and perturbed simulations are mainly due to the imposed warming and feedback influencing the synoptic flow. The mean precipitation change with warming in the central Indian region is 18-20 %/K, with largest changes at the end of the LPS tracks. The LPS in the warmer runs are bringing more moisture further inland that is released as precipitation. In the perturbed runs the precipitation rate is increasing at all percentiles, and there is more frequent rainfall with very heavy intensities. This leads to a shift in which category that contributes most to the total precipitation: more of the precipitation is coming from the category with very heavy intensities. The runoff changes are similar to the precipitation changes, except the response in intensity of very heavy runoff, which is around twice the change in intensity of very heavy precipitation.

  8. Holocene high-resolution quantitative summer temperature reconstruction based on subfossil chironomids from the southeast margin of the Qinghai-Tibetan Plateau

    Science.gov (United States)

    Zhang, Enlou; Chang, Jie; Cao, Yanmin; Sun, Weiwei; Shulmeister, James; Tang, Hongqu; Langdon, Peter G.; Yang, Xiangdong; Shen, Ji

    2017-06-01

    This paper reports the first quantitative summer (mean July) temperature reconstruction based on subfossil chironomids from the southeast margin of the Qinghai-Tibetan Plateau (QTP) covering the end of the last deglaciation and the entire Holocene, spanning 11,800 cal yr BP to the present. The record is based on 223 chironomid samples throughout a 927 cm sediment core providing a temporal resolution of ∼50 years per sample. We validate the record by applying several statistical reconstruction diagnostics and comparing with pollen and diatom records from the same sediment core. The record suggests the summer temperature varies by ∼2.5 °C across the entire period. A generally warmer period occurred between c.8500 and c.6000 cal yr BP and a cooling trend was initiated from c.5500 cal yr BP. The overall pattern broadly matches the summer insolation at 30°N and the Asian Summer Monsoon records from the surrounding regions suggesting that summer temperatures from the southeast margin of the QTP respond to insolation forcing and monsoon driven variability on a multi-millennial time scale. Modifications of this overall trend are observed on the finer temporal resolution and we suggest that solar activity could be an important mechanism driving the centennial-scale variability. It may have a strengthened effect in the late Holocene when the monsoon influence weakened. Further detailed investigation is needed to disentangle these effects on the climate change over the highlands of southwestern China.

  9. Extreme High and Low Temperature Operation of the Silicon-On-Insulator Type CHT-OPA Operational Amplifier

    Science.gov (United States)

    Patterson, Richard; Hammoud, Ahmad; Elbuluk, Malik

    2008-01-01

    A new operational amplifier chip based on silicon-on-insulator technology was evaluated for potential use in extreme temperature environments. The CHT-OPA device is a low power, precision operational amplifier with rail-to-rail output swing capability, and it is rated for operation between -55 C and +225 C. A unity gain inverting circuit was constructed utilizing the CHT-OPA chip and a few passive components. The circuit was evaluated in the temperature range from -190 C to +200 C in terms of signal gain and phase shift, and supply current. The investigations were carried out to determine suitability of this device for use in space exploration missions and aeronautic applications under wide temperature incursion. Re-restart capability at extreme temperatures, i.e. power switched on while the device was soaked at extreme temperatures, was also investigated. In addition, the effects of thermal cycling under a wide temperature range on the operation of this high performance amplifier were determined. The results from this work indicate that this silicon-on-insulator amplifier chip maintained very good operation between +200 C and -190 C. The limited thermal cycling had no effect on the performance of the amplifier, and it was able to re-start at both -190 C and +200 C. In addition, no physical degradation or packaging damage was introduced due to either extreme temperature exposure or thermal cycling. The good performance demonstrated by this silicon-on-insulator operational amplifier renders it a potential candidate for use in space exploration missions or other environments under extreme temperatures. Additional and more comprehensive characterization is, however, required to establish the reliability and suitability of such devices for long term use in extreme temperature applications.

  10. Thermodynamic Properties of Gaseous Plasmas in the Limit of Extremely Low Temperature

    CERN Document Server

    Iosilevskiy, Igor

    2010-01-01

    Limiting structure of thermodynamic functions of gaseous plasmas is under consideration in the limit of zero temperature and density. Remarkable tendency, which was claimed previously (Iosilevskiy and Gryaznov, 1985) is carried to extreme. Both equations of state, thermal and caloric ones obtain in this limit identical stepped structure ("ionization stairs") for plasma of any single element when this limit (T -> 0, n -> 0) is carried out at fixed value of chemical potential for electrons (or atoms). The same stepped structure is valid for plasma of mixtures or compounds. This structure appears within a fixed (negative) range of chemical potential of electrons bounded below by value of major ionization potential of element and above by the value depending on sublimation energy of substance. Binding energies of all possible bound complexes (atomic, molecular, ionic and clusters) in its ground state are the only quantities that manifest itself in meaningful details of this limiting picture as location and value ...

  11. On regional dynamical downscaling for the assessment and projection of temperature and precipitation extremes across Tasmania, Australia

    Science.gov (United States)

    White, Christopher J.; McInnes, Kathleen L.; Cechet, Robert P.; Corney, Stuart P.; Grose, Michael R.; Holz, Gregory K.; Katzfey, Jack J.; Bindoff, Nathaniel L.

    2013-12-01

    The ability of an ensemble of six GCMs, downscaled to a 0.1° lat/lon grid using the Conformal Cubic Atmospheric Model over Tasmania, Australia, to simulate observed extreme temperature and precipitation climatologies and statewide trends is assessed for 1961-2009 using a suite of extreme indices. The downscaled simulations have high skill in reproducing extreme temperatures, with the majority of models reproducing the statewide averaged sign and magnitude of recent observed trends of increasing warm days and warm nights and decreasing frost days. The warm spell duration index is however underestimated, while variance is generally overrepresented in the extreme temperature range across most regions. The simulations show a lower level of skill in modelling the amplitude of the extreme precipitation indices such as very wet days, but simulate the observed spatial patterns and variability. In general, simulations of dry extreme precipitation indices are underestimated in dryer areas and wet extremes indices are underestimated in wetter areas. Using two SRES emissions scenarios, the simulations indicate a significant increase in warm nights compared to a slightly more moderate increase in warm days, and an increase in maximum 1- and 5- day precipitation intensities interspersed with longer consecutive dry spells across Tasmania during the twenty-first century.

  12. Biodiversity and geochemistry of an extremely acidic, low-temperature subterranean environment sustained by chemolithotrophy.

    Science.gov (United States)

    Kimura, Sakurako; Bryan, Christopher G; Hallberg, Kevin B; Johnson, D Barrie

    2011-08-01

    The geochemical dynamics and composition of microbial communities within a low-temperature (≈ 8.5°C), long-abandoned (> 90 years) underground pyrite mine (Cae Coch, located in north Wales) were investigated. Surface water percolating through fractures in the residual pyrite ore body that forms the roof of the mine becomes extremely acidic and iron-enriched due to microbially accelerated oxidative dissolution of the sulfide mineral. Water droplets on the mine roof were found to host a very limited diversity of exclusively autotrophic microorganisms, dominated by the recently described psychrotolerant iron/sulfur-oxidizing acidophile Acidithiobacillus ferrivorans, and smaller numbers of iron-oxidizing Leptospirillum ferrooxidans. In contrast, flowing water within the mine chamber was colonized with vast macroscopic microbial growths, in the form of acid streamers and microbial stalactites, where the dominant microorganisms were Betaproteobacteria (autotrophic iron oxidizers such as 'Ferrovum myxofaciens' and a bacterium related to Gallionella ferruginea). An isolated pool within the mine showed some similarity (although greater biodiversity) to the roof droplets, and was the only site where archaea were relatively abundant. Bacteria not previously associated with extremely acidic, metal-rich environments (a Sphingomonas sp. and Ralstonia pickettii) were found within the abandoned mine. Data supported the hypothesis that the Cae Coch ecosystem is underpinned by acidophilic, mostly autotrophic, bacteria that use ferrous iron present in the pyrite ore body as their source of energy, with a limited role for sulfur-based autotrophy. Results of this study highlight the importance of novel bacterial species (At. ferrivorans and acidophilic iron-oxidizing Betaproteobacteria) in mediating mineral oxidation and redox transformations of iron in acidic, low-temperature environments. © 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.

  13. Summer Appendicitis

    African Journals Online (AJOL)

    hanumantp

    diet, during summer months could be contribute to the higher incidence of appendicitis ... To examine the global trends in the seasonality of appendicitis, .... Iran. Summer. [11]. 1998-2004. 1331. Italy. Summer. [12]. 1991-1998. 65,675. Canada.

  14. What matters most: Are summer stream temperatures more sensitive to changing air temperature, changing discharge, or changing riparian vegetation under future climates?

    Science.gov (United States)

    Diabat, M.; Haggerty, R.; Wondzell, S. M.

    2012-12-01

    We investigated stream temperature responses to changes in both air temperature and stream discharge projected for 2040-2060 from downscaled GCMs and changes in the height and canopy density of streamside vegetation. We used Heat Source© calibrated for a 37 km section of the Middle Fork John Day River located in Oregon, USA. The analysis used the multiple-variable-at-a-time (MVAT) approach to simulate various combinations of changes: 3 levels of air warming, 5 levels of stream flow (higher and lower discharges), and 6 types of streamside vegetation. Preliminary results show that, under current discharge and riparian vegetation conditions, projected 2 to 4 °C increase in air temperature will increase the 7-day Average Daily Maximum Temperature (7dADM) by 1 to 2 °C. Changing stream discharge by ±30% changes stream temperature by ±0.5 °C, and the influence of changing discharge is greatest when the stream is poorly shaded. In contrast, the 7dADM could change by as much as 11°C with changes in riparian vegetation from unshaded conditions to heavily shaded conditions along the study section. The most heavily shaded simulations used uniformly dense riparian vegetation over the full 37-km reach, and this vegetation was composed of the tallest trees and densest canopies that can currently occur within the study reach. While this simulation represents an extreme case, it does suggest that managing riparian vegetation to substantially increase stream shade could decrease 7dADM temperatures relative to current temperatures, even under future climates when mean air temperatures have increased from 2 to 4 °C.

  15. Multi-scenario-based hazard analysis of high temperature extremes experienced in China during 1951-2010

    Institute of Scientific and Technical Information of China (English)

    YIN Zhan'e; YIN Jie; ZHANG Xiaowei

    2013-01-01

    China is physically and socio-economically susceptible to global warming-derived high temperature extremes because of its vast area and high urban population density.This article presents a scenario-based analysis method for high temperature extremes aimed at illustrating the latter's hazardous potential and exposure across China.Based on probability analysis,high temperature extreme scenarios with return periods of 5,10,20,and 50 years were designed,with a high temperature hazard index calculated by integrating two differentially-weighted extreme temperature indices (maximum temperature and high temperature days).To perform the exposure analysis,a land use map was employed to determine the spatial distribution of susceptible human activities under the different scenarios.The results indicate that there are two heat-prone regions and a sub-hotspot occupying a relatively small land area.However,the societal and economic consequences of such an environmental impact upon the North China Plain and middle/lower Yangtze River Basin would be substantial due to the concentration of human activities in these areas.

  16. Analysis and Comparison of Trends in Extreme Temperature Indices in Riyadh City, Kingdom of Saudi Arabia, 1985–2010

    OpenAIRE

    Ali S. Alghamdi; Todd W. Moore

    2014-01-01

    This study employed the time series of thirteen extreme temperature indices over the period 1985–2010 to analyze and compare temporal trends at two weather stations in Riyadh city, Saudi Arabia. The trend analysis showed warming of the local air for the city. Significant increasing trends were found in annual average maximum and minimum temperatures, maximum of minimum temperature, warm nights, and warm days for an urban and a rural station. Significant decreasing trends were detected in the ...

  17. Genetic assessment of rectal temperature and coat score in Brahman, Angus, and Romosinuano crossbred and straightbred cows and calves under subtropical summer conditions

    Science.gov (United States)

    The objectives of this study were to characterize rectal temperature and coat score under subtropical North American summer conditions for straightbred and crossbred Romosinuano, Brahman, and Angus cattle, to estimate heterosis and breed direct and maternal effects in a subset of those, and to estim...

  18. Response of Bacillus subtilis spores to dehydration and UV irradiation at extremely low temperatures.

    Science.gov (United States)

    Dose, K; Klein, A

    1996-02-01

    Spores of Bacillus subtilis have been exposed to the conditions of extreme dehydration (argon/silica gel; simulated space vacuum) for up to 12 weeks at 298 K and 80 K in the dark. The inactivation has been correlated with the production of DNA-double strand-breaks. The temperature-dependence of the rate constants for inactivation or production of DNA-double strand-breaks is surprisingly low. Controls kept in the frozen state at 250 K for the same period of time showed no sign of deterioration. In another series of experiments the spores have been UV irradiated (253.7 nm) at 298 K, 200 K and 80 K after exposure to dehydrating conditions for 3 days. Fluence-effect relationships for inactivation, production of DNA-double strand-breaks and DNA-protein cross-links are presented. The corresponding F37-values for inactivation and production of DNA lesions are significantly increased only at 80 K (factor of 4 to 5). The data indicate that the low temperatures that prevail in the outer parts of the Solar System or at the nightside of Mars or the Moon are not sufficiently low to crucially inhibit inactivation by dehydration. Our data place further constraints on the panspermia hypothesis.

  19. Short-term cropland responses to temperature extreme events during late winter

    Directory of Open Access Journals (Sweden)

    G. De Simon

    2013-04-01

    Full Text Available In recent years, several studies have focused on terrestrial ecosystem response to extreme events. Most of this research has been conducted in natural ecosystems, but few have considered agro-ecosystems. In this study, we investigated the impact of a manipulated warmer or cooler late winter-early spring on the carbon budget and final harvest of a soybean crop (Glycine max (L. Merr.. Soil temperature was altered by manipulating soil albedo by covering the soil surface with a layer of inert silica gravel. We tested three treatments: cooling (Co, warming (W, mix (M and control (C. An automated system continuously measured soil heterotrophic respiration (Rh, soil temperature profiles, and soil water content across the entire year in each plot. Phenological phases were periodically assessed and final harvest was measured in each plot. Results showed that treatments had only a transient effect on daily Rh rates which did not result in a total annual carbon budget significantly different from control, even though cooling showed a significant reduction in final harvest. We also observed anticipation in seed germination in both W and M treatments and a delay in germination for Co. Moreover, plant density and growth increased in W and M and decreased in Co.

  20. Simulation evaluation and future prediction of the IPCC-AR4 GCMs on the extreme temperatures in China

    Institute of Scientific and Technical Information of China (English)

    WANG Ji; JIANG Zhihong; SONG Jie; LOU Dejun

    2008-01-01

    On the basis of the temperature observations during 1961-2000 in China, seven coupled general circulation models' (GCMs) extreme temperature products are evaluated supplied by the Intergovemmental Panel on Climate Change's 4th Assessment Report (IPCC-AR4). The extreme temperature indices in use are frost days (FD), growing season length (GSL), extreme tempera-ture range (ETR), warm nights (TN90), and heat wave duration index (HWDI). Results indicate that all the seven models are capable of simulating spatial and temporal variations in temperature characteristics, and their ensemble acts more reliable than any single one. Among the seven models, GFDL-CM2.0 and MIROC3.2 performances are much better. Besides, most of the mod-els are able to present linear trends of the same positive/negative signs as the observations but for weaker intensities. The simula-tion effects are different on a nationwide basis, with 110°N as the division, east (west) of which the effects are better (worse) and the poorer over the Qinghai-Tibetan Plateau in China. The predictions for the 21st century on emissions scenarios show that except decreases in the FD and ETR, other indices display significant increasing trend, especially for the indices of HWDI and TN90, which represent the notable extreme climate. This indicates that the temperature-related climate is moving towards the ex-treme. In the late 21st century, the GSL and TN90 (HWDI) increase most notably in southwest China (the Qinghai--Tibetan Plateau), and the FD decrease most remarkably in the Qinghai-Tibetan Plateau, northwest and northeast of China. Apart from South China, the yearly change range of the extreme temperature is reduced in most of China.