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Sample records for additional heat wave

  1. Heat Wave Safety Checklist

    MedlinePlus

    ... heat has caused more deaths than all other weather events, including floods. A heat wave is a ... care for heat- related emergencies … ❏ Listen to local weather forecasts and stay aware of upcoming temperature changes. ❏ ...

  2. [Heat waves: health impacts].

    PubMed

    Marto, Natália

    2005-01-01

    During the summer of 2003, record high temperatures were reported across Europe, causing thousands of casualties. Heat waves are sporadic recurrent events, characterised by intense and prolonged heat, associated with excess mortality and morbidity. The most frequent cause of death directly attributable to heat is heat stroke but heat waves are known to cause increases in all-cause mortality, specially circulatory and respiratory mortality. Epidemiological studies demonstrate excess casualties cluster in specific risk groups. The elderly, those with chronic medical conditions and the socially isolated are particularly vulnerable. Air conditioning is the strongest protective factor against heat-related disorders. Heat waves cause disease indirectly, by aggravating chronic disorders, and directly, by causing heat-related illnesses (HRI). Classic HRI include skin eruptions, heat cramps, heat syncope, heat exhaustion and heat stroke. Heat stroke is a medical emergency characterised by hyperthermia and central nervous system dysfunction. Treatment includes immediate cooling and support of organ-system function. Despite aggressive treatment, heat stroke is often fatal and permanent neurological damage is frequent in those who survive. Heat related illness and death are preventable through behavioural adaptations, such as use of air conditioning and increased fluid intake. Other adaptation measures include heat emergency warning systems and intervention plans and environmental heat stress reduction. Heat related mortality is expected to rise as a consequence of the increasing proportion of elderly persons, the growing urban population, and the anticipated increase in number and intensity of heat waves associated with global warming. Improvements in surveillance and response capability may limit the adverse health conditions of future heat waves. It is crucial that health professionals are prepared to recognise, prevent and treat HRI and learn to cooperate with local health

  3. The 2003 heat wave.

    PubMed

    Sardon, J-P

    2007-03-01

    The July-August 2005 issue of Eurosurveillance focused on the impact on mortality of the 2003 heat wave in Europe, with articles that were based on various methods and looked at different time periods [1]. The subject of this letter is to assess, using a unique methodology, the excess mortality related to the 2003 heat wave across the continent. PMID:17439811

  4. Ion Bernstein wave heating research

    SciTech Connect

    Ono, Masayuki.

    1992-03-01

    Ion Bernstein wave heating (IBWH) utilizes the ion Bernstein wave (IBW), a hot plasma wave, to carry the radio frequency (rf) power to heat tokamak reactor core. Earlier wave accessibility studies have shown that this finite-Larmor-radius (FLR) mode should penetrate into a hot dense reactor plasma core without significant attenuation. Moreover, the IBW's low phase velocity ({omega}/k{sub {perpendicular}} {approx} V{sub Ti} {much lt} V{sub {alpha}}) greatly reduces the otherwise serious wave absorption by the 3.5 MeV fusion {alpha}-particles. In addition, the property of IBW's that k{sub {perpendicular}} {rho}{sub i} {approx} 1 makes localized bulk ion heating possible at the ion cyclotron harmonic layers. Such bulk ion heating can prove useful in optimizing fusion reactivity. In another vein, with proper selection of parameters, IBW's can be made subject to strong localized electron Landau damping near the major ion cyclotron harmonic resonance layers. This property can be useful, for example, for rf current drive in the reactor plasma core. This paper discusses this research.

  5. Ion Bernstein wave heating research

    SciTech Connect

    Ono, Masayuki

    1992-03-01

    Ion Bernstein wave heating (IBWH) utilizes the ion Bernstein wave (IBW), a hot plasma wave, to carry the radio frequency (rf) power to heat tokamak reactor core. Earlier wave accessibility studies have shown that this finite-Larmor-radius (FLR) mode should penetrate into a hot dense reactor plasma core without significant attenuation. Moreover, the IBW`s low phase velocity ({omega}/k{sub {perpendicular}} {approx} V{sub Ti} {much_lt} V{sub {alpha}}) greatly reduces the otherwise serious wave absorption by the 3.5 MeV fusion {alpha}-particles. In addition, the property of IBW`s that k{sub {perpendicular}} {rho}{sub i} {approx} 1 makes localized bulk ion heating possible at the ion cyclotron harmonic layers. Such bulk ion heating can prove useful in optimizing fusion reactivity. In another vein, with proper selection of parameters, IBW`s can be made subject to strong localized electron Landau damping near the major ion cyclotron harmonic resonance layers. This property can be useful, for example, for rf current drive in the reactor plasma core. This paper discusses this research.

  6. Optimization of microwave heating in an existing cubicle cavity by incorporating additional wave guide and control components

    SciTech Connect

    Erle, R.R.; Eschen, V.G.; Sprenger, G.S.

    1995-04-01

    The use of microwave energy to thermally treat Low Level (LLW), Transuranic (TRU), and mixed waste has been under development at the Rocky Flats Environmental Technology Site (Site) since 1986. During that time, the technology has progressed from bench-scale tests, through pilot-scale tests, and finally to a full-scale demonstration unit. Experimental operations have been conducted on a variety of non-radioactive surrogates and actual radioactive waste forms. Through these studies and development efforts, the Microwave Vitrification Engineering Team (MVET) at Rocky Flats has successfully proven the application of microwave energy for waste treatment operations. In the microwave solidification process, microwave energy is used to heat a mixture of waste and glass frit to produce a vitrified product that meets all the current acceptance criteria at the final disposal sites. All of the development to date has utilized a multi-mode microwave system to provide the energy to treat the materials. Currently, evaluations are underway on modifications to the full-scale demonstration system that provide a single-mode operation as a possible method to optimize the system. This poster presentation describes the modifications made to allow the single-mode operation.

  7. Effects of simulated heat waves on ApoE-/- mice.

    PubMed

    Wang, Chunling; Zhang, Shuyu; Tian, Ying; Wang, Baojian; Shen, Shuanghe

    2014-02-01

    The effects of simulated heat waves on body weight, body temperature, and biomarkers of cardiac function in ApoE-/- mice were investigated. Heat waves were simulated in a meteorological environment simulation chamber according to data from a heat wave that occurred in July 2001 in Nanjing, China. Eighteen ApoE-/- mice were divided into control group, heat wave group, and heat wave BH4 group. Mice in the heat wave and BH4 groups were exposed to simulated heat waves in the simulation chamber. Mice in BH4 group were treated with gastric lavage with BH4 2 h prior to heat wave exposure. Results showed that the heat waves did not significantly affect body weight or ET-1 levels. However, mice in the heat wave group had significantly higher rectal temperature and NO level and lower SOD activity compared with mice in the control group (p < 0.01), indicating that heat wave had negative effects on cardiac function in ApoE-/- mice. Gastric lavage with BH4 prior to heat wave exposure significantly reduced heat wave-induced increases in rectal temperature and decreases in SOD activity. Additionally, pretreatment with BH4 further increased NO level in plasma. Collectively, these beneficial effects demonstrate that BH4 may potentially mitigate the risk of coronary heart disease in mice under heat wave exposure. These results may be useful when studying the effects of heat waves on humans. PMID:24477215

  8. Effects of simulated heat waves on ApoE-/- mice.

    PubMed

    Wang, Chunling; Zhang, Shuyu; Tian, Ying; Wang, Baojian; Shen, Shuanghe

    2014-02-01

    The effects of simulated heat waves on body weight, body temperature, and biomarkers of cardiac function in ApoE-/- mice were investigated. Heat waves were simulated in a meteorological environment simulation chamber according to data from a heat wave that occurred in July 2001 in Nanjing, China. Eighteen ApoE-/- mice were divided into control group, heat wave group, and heat wave BH4 group. Mice in the heat wave and BH4 groups were exposed to simulated heat waves in the simulation chamber. Mice in BH4 group were treated with gastric lavage with BH4 2 h prior to heat wave exposure. Results showed that the heat waves did not significantly affect body weight or ET-1 levels. However, mice in the heat wave group had significantly higher rectal temperature and NO level and lower SOD activity compared with mice in the control group (p < 0.01), indicating that heat wave had negative effects on cardiac function in ApoE-/- mice. Gastric lavage with BH4 prior to heat wave exposure significantly reduced heat wave-induced increases in rectal temperature and decreases in SOD activity. Additionally, pretreatment with BH4 further increased NO level in plasma. Collectively, these beneficial effects demonstrate that BH4 may potentially mitigate the risk of coronary heart disease in mice under heat wave exposure. These results may be useful when studying the effects of heat waves on humans.

  9. Ion Bernstein wave heating research

    NASA Astrophysics Data System (ADS)

    Ono, Masayuki

    1993-02-01

    Ion Bernstein wave heating (IBWH) utilizes the ion Bernstein wave (IBW), a hot plasma wave, to carry the radio frequency (rf) power to heat the tokamak reactor core. Earlier wave accessibility studies have shown that this finite-Larmor-radius (FLR) mode should penetrate into a hot dense reactor plasma core without significant attenuation. Moreover, the IBW's low perpendicular phase velocity (ω/k⊥≊VTi≪Vα) greatly reduces the otherwise serious wave absorption by the 3.5 MeV fusion α particles. In addition, the property of IBW's that k⊥ρi≊1 makes localized bulk ion heating possible at the ion cyclotron harmonic layers. Such bulk ion heating can prove useful in optimizing fusion reactivity. In another vein, with proper selection of parameters, IBW's can be made subject to strong localized electron Landau damping near the major ion cyclotron harmonic resonance layers. This property can be useful, for example, for rf current drive in the reactor plasma core. IBW's can be excited with loop antennas or with a lower-hybrid-like waveguide launcher at the plasma edge, the latter structure being one that is especially compatible with reactor application. In either case, the mode at the plasma edge is an electron plasma wave (EPW). Deeper in the plasma, the EPW is mode transformed into an IBW. Such launching and mode transformation of IBW's were first demonstrated in experiments in the Advanced Concepts Torus-1 (ACT-1) [Phys. Rev. Lett. 45, 1105 (1980)] plasma torus and in particle simulation calculations. These and other aspects of IBW heating physics have been investigated through a number of experiments performed on ACT-1, the Japanese Institute of Plasma Physics Tokamak II-Upgrade (JIPPTII-U) [Phys. Rev. Lett. 54, 2339 (1985)], the Tokyo University Non-Circular Tokamak (TNT) [Nucl. Fusion 26, 1097 (1986)], the Princeton Large Tokamak (PLT) [Phys. Rev. Lett. 60, 294 (1988)], and Alcator-C [Phys. Rev. Lett. 60, 298 (1988)]. In these experiments both linear and

  10. Additional waves in the graphene layered medium.

    PubMed

    Chern, Ruey-Lin; Han, Dezhuan; Zhang, Z Q; Chan, C T

    2014-12-29

    We investigate the features of additional waves that arise in the graphene layered medium, within the framework of nonlocal effective medium model. The additional wave is manifest on the biquadratic dispersion relation of the medium and represents as a distinctive nonlocal character at long wavelength. In particular, the reflection and transmission coefficients for the nonlocal medium are underdetermined by Maxwell's boundary conditions. An additional boundary condition based on modal expansions is proposed to derive the generalized Fresnel equations, based on which the additional wave in the graphene layered medium is determined. The additional wave tends to be significant near the effective plasma frequency, near which the graphene plasmons are excited inside the medium. PMID:25607138

  11. Northern Eurasian Heat Waves and Droughts

    NASA Technical Reports Server (NTRS)

    Schubert, Siegfried; Wang, Hailan; Koster, Randal; Suarez, Max; Groisman, Pavel

    2013-01-01

    This article reviews our understanding of the characteristics and causes of northern Eurasian summertime heat waves and droughts. Additional insights into the nature of temperature and precipitation variability in Eurasia on monthly to decadal time scales and into the causes and predictability of the most extreme events are gained from the latest generation of reanalyses and from supplemental simulations with the NASA GEOS-5 AGCM. Key new results are: 1) the identification of the important role of summertime stationary Rossby waves in the development of the leading patterns of monthly Eurasian surface temperature and precipitation variability (including the development of extreme events such as the 2010 Russian heat wave), 2) an assessment of the mean temperature and precipitation changes that have occurred over northern Eurasia in the last three decades and their connections to decadal variability and global trends in SST, and 3) the quantification (via a case study) of the predictability of the most extreme simulated heat wave/drought events, with some focus on the role of soil moisture in the development and maintenance of such events. A literature survey indicates a general consensus that the future holds an enhanced probability of heat waves across northern Eurasia, while there is less agreement regarding future drought, reflecting a greater uncertainty in soil moisture and precipitation projections. Substantial uncertainties remain in our understanding of heat waves and drought, including the nature of the interactions between the short-term atmospheric variability associated with such extremes and the longer-term variability and trends associated with soil moisture feedbacks, SST anomalies, and an overall warming world.

  12. Impact of Heat Wave Definitions on the Added Effect of Heat Waves on Cardiovascular Mortality in Beijing, China

    PubMed Central

    Dong, Wentan; Zeng, Qiang; Ma, Yue; Li, Guoxing; Pan, Xiaochuan

    2016-01-01

    Heat waves are associated with increased mortality, however, few studies have examined the added effect of heat waves. Moreover, there is limited evidence for the influence of different heat wave definitions (HWs) on cardiovascular mortality in Beijing, the capital of China. The aim of this study was to find the best HW definitions for cardiovascular mortality, and we examined the effect modification by an individual characteristic on cardiovascular mortality in Beijing, a typical northern city in China. We applied a Poisson generalized additive approach to estimate the differences in cardiovascular mortality during heat waves (using 12 HWs) compared with non-heat-wave days in Beijing from 2006 to 2009. We also validated the model fit by checking the residuals to ensure that the autocorrelation was successfully removed. In addition, the effect modifications by individual characteristics were explored in different HWs. Our results showed that the associations between heat waves and cardiovascular mortality differed from different HWs. HWs using the 93th percentile of the daily average temperature (27.7 °C) and a duration ≥5 days had the greatest risk, with an increase of 18% (95% confidence interval (CI): 6%, 31%) in the overall population, 24% (95% CI: 10%, 39%) in an older group (ages ≥65 years), and 22% (95% CI: 3%, 44%) in a female group. The added effect of heat waves was apparent after 5 consecutive heat wave days for the overall population and the older group. Females and the elderly were at higher risk than males and younger subjects (ages <65 years). Our findings suggest that heat wave definitions play a significant role in the relationship between heat wave and cardiovascular mortality. Using a suitable definition may have implications for designing local heat early warning systems and protecting the susceptible populations during heat waves. PMID:27657103

  13. Wave heating of the solar atmosphere

    PubMed Central

    Arregui, Iñigo

    2015-01-01

    Magnetic waves are a relevant component in the dynamics of the solar atmosphere. Their significance has increased because of their potential as a remote diagnostic tool and their presumed contribution to plasma heating processes. We discuss our current understanding of coronal heating by magnetic waves, based on recent observational evidence and theoretical advances. The discussion starts with a selection of observational discoveries that have brought magnetic waves to the forefront of the coronal heating discussion. Then, our theoretical understanding of the nature and properties of the observed waves and the physical processes that have been proposed to explain observations are described. Particular attention is given to the sequence of processes that link observed wave characteristics with concealed energy transport, dissipation and heat conversion. We conclude with a commentary on how the combination of theory and observations should help us to understand and quantify magnetic wave heating of the solar atmosphere. PMID:25897091

  14. Wave heating of the solar atmosphere.

    PubMed

    Arregui, Iñigo

    2015-05-28

    Magnetic waves are a relevant component in the dynamics of the solar atmosphere. Their significance has increased because of their potential as a remote diagnostic tool and their presumed contribution to plasma heating processes. We discuss our current understanding of coronal heating by magnetic waves, based on recent observational evidence and theoretical advances. The discussion starts with a selection of observational discoveries that have brought magnetic waves to the forefront of the coronal heating discussion. Then, our theoretical understanding of the nature and properties of the observed waves and the physical processes that have been proposed to explain observations are described. Particular attention is given to the sequence of processes that link observed wave characteristics with concealed energy transport, dissipation and heat conversion. We conclude with a commentary on how the combination of theory and observations should help us to understand and quantify magnetic wave heating of the solar atmosphere. PMID:25897091

  15. Heat waves and urban heat islands in Europe: A review of relevant drivers.

    PubMed

    Ward, Kathrin; Lauf, Steffen; Kleinschmit, Birgit; Endlicher, Wilfried

    2016-11-01

    The climate change and the proceeding urbanization create future health challenges. Consequently, more people around the globe will be impaired by extreme weather events, such as heat waves. This study investigates the causes for the emergence of surface urban heat islands and its change during heat waves in 70 European cities. A newly created climate class indicator, a set of meaningful landscape metrics, and two population-related parameters were applied to describe the Surface Urban Heat Island Magnitude (SUHIM) - the mean temperature increase within the urban heat island compared to its surrounding, as well as the Heat Magnitude (HM) - the extra heat load added to the average summer SUHIM during heat waves. We evaluated the relevance of varying urban parameters within linear models. The exemplary European-wide heat wave in July 2006 was chosen and compared to the average summer conditions using MODIS land surface temperature with an improved spatial resolution of 250m. The results revealed that the initial size of the urban heat island had significant influence on SUHIM. For the explanation of HM the size of the heat island, the regional climate and the share of central urban green spaces showed to be critical. Interestingly, cities of cooler climates and cities with higher shares of urban green spaces were more affected by additional heat during heat waves. Accordingly, cooler northern European cities seem to be more vulnerable to heat waves, whereas southern European cities appear to be better adapted. Within the ascertained population and climate clusters more detailed explanations were found. Our findings improve the understanding of the urban heat island effect across European cities and its behavior under heat waves. Also, they provide some indications for urban planners on case-specific adaptation strategies to adverse urban heat caused by heat waves.

  16. Heat waves and urban heat islands in Europe: A review of relevant drivers.

    PubMed

    Ward, Kathrin; Lauf, Steffen; Kleinschmit, Birgit; Endlicher, Wilfried

    2016-11-01

    The climate change and the proceeding urbanization create future health challenges. Consequently, more people around the globe will be impaired by extreme weather events, such as heat waves. This study investigates the causes for the emergence of surface urban heat islands and its change during heat waves in 70 European cities. A newly created climate class indicator, a set of meaningful landscape metrics, and two population-related parameters were applied to describe the Surface Urban Heat Island Magnitude (SUHIM) - the mean temperature increase within the urban heat island compared to its surrounding, as well as the Heat Magnitude (HM) - the extra heat load added to the average summer SUHIM during heat waves. We evaluated the relevance of varying urban parameters within linear models. The exemplary European-wide heat wave in July 2006 was chosen and compared to the average summer conditions using MODIS land surface temperature with an improved spatial resolution of 250m. The results revealed that the initial size of the urban heat island had significant influence on SUHIM. For the explanation of HM the size of the heat island, the regional climate and the share of central urban green spaces showed to be critical. Interestingly, cities of cooler climates and cities with higher shares of urban green spaces were more affected by additional heat during heat waves. Accordingly, cooler northern European cities seem to be more vulnerable to heat waves, whereas southern European cities appear to be better adapted. Within the ascertained population and climate clusters more detailed explanations were found. Our findings improve the understanding of the urban heat island effect across European cities and its behavior under heat waves. Also, they provide some indications for urban planners on case-specific adaptation strategies to adverse urban heat caused by heat waves. PMID:27366983

  17. Heat Waves Are Health Threats

    MedlinePlus

    ... heat syncope (fainting), heat exhaustion, as well as heat stroke," he said in a hospital news release. "Various classes of medications including beta blockers, as well as diuretics, can ... to heat-related illnesses," Glatter said. But young, healthy people ...

  18. Study of heat-stress levels in naturally ventilated sheep barns during heat waves: development and assessment of regression models

    NASA Astrophysics Data System (ADS)

    Papanastasiou, D. K.; Bartzanas, T.; Panagakis, P.; Zhang, G.; Kittas, C.

    2016-03-01

    It is well documented that heat-stress burdens sheep welfare and productivity. Peak heat-stress levels are observed when high temperatures prevail, i.e. during heat waves; however, continuous measurements inside livestock buildings are not usually available for long periods so as to study the variation of summer heat-stress levels for several years, especially during extreme hot weather. Α methodology to develop a long time series of summer temperature and relative humidity inside naturally ventilated sheep barns is proposed. The accuracy and the transferability of the developed linear regression models were verified. Temperature Humidity Index (THI) was used to assess sheep's potential heat-stress. Τhe variation of THI inside a barn during heat wave and non-heat wave days was examined, and the results were comparatively assessed. The analysis showed that sheep were exposed to moderate, severe, and extreme severe heat-stress in 10, 21 and 66 % of hours, respectively, during heat wave days, while the corresponding values during non-heat wave days were 14, 33 and 43 %, respectively. The heat load on sheep was much higher during heat wave events than during non-heat wave periods. Additionally, based on the averaged diurnal variation of THI, it was concluded that extreme severe heat-stress conditions were prevailing between 1000 and 2400 hours local time during heat wave days. Cool off night periods were never and extremely rarely detected during heat wave and non-heat wave days, respectively.

  19. Closing the Gap on Measuring Heat Waves

    NASA Astrophysics Data System (ADS)

    Perkins, S. E.; Alexander, L.

    2012-12-01

    Since the 4th IPCC assessment report, the scientific literature has established that anthropogenic climate change encompasses adverse changes in both mean climate conditions and extreme events, such as heat waves. Indeed, the affects of heat waves are felt across many different sectors, and have high economic, human, and physical impacts over many global regions. The spatial and monetary scale of heat wave impacts emphasizes the necessity of measuring and studying such events in an informative manner, which gives justice to the geographical region affected, the communities impacted, and the climatic fields involved. However, due to such wide interest in heat waves, their definition remains broad in describing a period of consecutive days where conditions are excessively hotter than normal. This has allowed for the employment of a plethora of metrics, which are usually unique to a given sector, or do not appropriately describe some of the important features of heat wave events. As such, it is difficult to ascertain a clear message regarding changes in heat waves, both in the observed record and in projections of future climate. This study addresses this issue by developing a multi-index, multi-aspect framework in which to measure heat waves. The methodology was constructed by assessing a wide range of heat wave and heat wave-related indices, both proposed and employed in the scientific literature. The broad implications of the occurrences, frequency and duration of heat waves and respective changes were also highly considered. The resulting indices measure three or more consecutive days where 1) maximum temperature exceeds the 90th percentile (TX90pct); 2) minimum temperature exceeds the 90th percentile (TN90pct); and 3) daily average temperature has a positive excess heat factor (EHF). The 90th percentiles from which TX90pct and TN90pct are calculated are based on 15-day windows for each calendar day, whereas the EHF is based upon two pre-calculated indices that

  20. Future Heat Waves in Paris Metropolitan Area

    NASA Astrophysics Data System (ADS)

    Beaulant, A.; Lemonsu, A.; Somot, S.; Masson, V.

    2010-12-01

    Cities are particularly vulnerable to heat waves, firstly because they concentrate the majority of the population and, secondly because the heat island that characterizes the urban climate exacerbates heat wave effects. This work is part of the interdisciplinary VURCA project (Vulnerability of cities to heat waves), which deals with the evolution of heat wave events in the context of global warming, urban vulnerability and adaptation strategies. The aim of this study is to analyse urban heat wave events in present climate (1950-2009) and their evolution in an enhanced greenhouse gazes future climate (2010-2100). We used daily observations of temperature from several stations covering Paris metropolitan area and climate projections following three different IPCC-SRES scenarios (B1, A1B, A2) and issued from several ENSEMBLES regional climate models. The heat wave definition is based on the indexes of the operational French warning system. A heat wave is detected within observed or simulated time-series by a heat wave peak, when the temperatures exceed the value of the 99.9th percentile. Its duration is determined by all adjacent days to this peak, for which the temperatures are not durably smaller than the 99.9th percentile value minus 2 °C. The 99.9th percentile threshold is inferred from quantile-quantile plots produced for each climate model in comparison with observations for the reference period 1950-2000. Heat waves have been extracted within observations and 12 climatic simulations. The number of heat wave events and cumulated HW days per year have been calculated, the maximum being seven heat waves cumulating more than 60 HW days in one year in the case of the A2 scenario and until 50 days in the case of the more moderate A1B scenario. From 2050, the occurrence of three or four HW events per year is becoming the norm all scenarios taken together. The evolution of heat wave features has been analysed, highlighting the large variability of the climatic

  1. Heat waves in urban heat islands: interactions, impacts, and mitigation

    NASA Astrophysics Data System (ADS)

    Bou-Zeid, E.; Li, D.

    2013-12-01

    Urbanization rates and the intensity of anthropogenic global warming are both on the rise. By the middle of this century, climate change impacts on humans will be largely manifested in urban regions and will result from a combination of global to regional impacts related to greenhouse gas emissions, as well as regional to local impacts related to land-cover changes associated with urbanization. Alarmingly, our understanding of how these two distinct impacts will interact remains very poor. One example, which is the focus of this study, is the interaction of urban heat islands and heat waves. Urban heat islands (UHIs) are spatial anomalies consisting of higher temperatures over built terrain; while their intensity varies with many factors, it consistently increases with city size. UHIs will hence intensify in the future as cities expand. Heat waves are temporal anomalies in the regional temperatures that affect both urban and rural areas; there is high certainty that the frequency and intensity of such waves will increase as a result global warming. However, whether urban and rural temperatures respond in the same way to heat waves remains a critical unanswered question. In this study, a combination of observational and modeling analyses of a heat wave event over the Baltimore-Washington urban corridor reveals synergistic interactions between urban heat islands and heat waves. Not only do heat waves increase the regional temperatures, but they also intensify the difference between urban and rural temperatures. That is, their impact is stronger in cities and the urban heat stress during such waves is larger than the sum of the background urban heat island effect and the heat wave effect. We also develop a simple analytical model of this interaction that suggests that this exacerbated impact in urban areas is primarily to the lack of surface moisture, with low wind speeds also playing a smaller role. Finally, the effectiveness of cool and green roofs as UHI mitigation

  2. Ion heating via turbulent ion acoustic waves.

    NASA Technical Reports Server (NTRS)

    Taylor, R. J.; Coroniti, F. V.

    1972-01-01

    The ion acoustic turbulence in the turbulent-heating experiment reported is excited by the ion-ion beam instability. Graphs are presented, showing the spatial evolution of the parallel ion beam energy and the spatial evolution of the ion acoustic turbulent wave spectrum. The observed characteristics of test waves in a turbulent beam-plasma imply that wave saturation is a dynamic balance between the emission of waves by the beam and the destruction or damping of wave coherence by the turbulent diffusion of particle orbits.

  3. Heat Exchange, Additive Manufacturing, and Neutron Imaging

    SciTech Connect

    Geoghegan, Patrick

    2015-02-23

    Researchers at the Oak Ridge National Laboratory have captured undistorted snapshots of refrigerants flowing through small heat exchangers, helping them to better understand heat transfer in heating, cooling and ventilation systems.

  4. Solar Coronal Heating via Alfven Wave Turbulence

    SciTech Connect

    Bigot, B.; Galtier, S.; Politano, H.

    2010-03-25

    A short review is given about the self-consistent MHD model of solar coronal heating recently proposed by Bigot et al.(2008) in which the dynamical effect of the background magnetic field along a coronal structure is taken into account through exact results from Alfven wave turbulence. The main properties of the model are given as well as the heating rate and the microturbulent velocity obtained in the case of coronal loops. The conclusion is that Alfven wave turbulence may produce an efficient background heating for the solar corona.

  5. On the physics of waves in the solar atmosphere: Wave heating and wind acceleration

    NASA Technical Reports Server (NTRS)

    Musielak, Z. E.

    1994-01-01

    This paper presents work performed on the generation and physics of acoustic waves in the solar atmosphere. The investigators have incorporated spatial and temporal turbulent energy spectra in a newly corrected version of the Lighthill-Stein theory of acoustic wave generation in order to calculate the acoustic wave energy fluxes generated in the solar convective zone. The investigators have also revised and improved the treatment of the generation of magnetic flux tube waves, which can carry energy along the tubes far away from the region of their origin, and have calculated the tube wave energy fluxes for the sun. They also examine the transfer of the wave energy originated in the solar convective zone to the outer atmospheric layers through computation of wave propagation and dissipation in highly nonhomogeneous solar atmosphere. These waves may efficiently heat the solar atmosphere and the heating will be especially significant in the chromospheric network. It is also shown that the role played by Alfven waves in solar wind acceleration and coronal hole heating is dominant. The second part of the project concerned investigation of wave propagation in highly inhomogeneous stellar atmospheres using an approach based on an analytic tool developed by Musielak, Fontenla, and Moore. In addition, a new technique based on Dirac equations has been developed to investigate coupling between different MHD waves propagating in stratified stellar atmospheres.

  6. Identifying Heat Waves in Florida: Considerations of Missing Weather Data

    PubMed Central

    Leary, Emily; Young, Linda J.; DuClos, Chris; Jordan, Melissa M.

    2015-01-01

    Background Using current climate models, regional-scale changes for Florida over the next 100 years are predicted to include warming over terrestrial areas and very likely increases in the number of high temperature extremes. No uniform definition of a heat wave exists. Most past research on heat waves has focused on evaluating the aftermath of known heat waves, with minimal consideration of missing exposure information. Objectives To identify and discuss methods of handling and imputing missing weather data and how those methods can affect identified periods of extreme heat in Florida. Methods In addition to ignoring missing data, temporal, spatial, and spatio-temporal models are described and utilized to impute missing historical weather data from 1973 to 2012 from 43 Florida weather monitors. Calculated thresholds are used to define periods of extreme heat across Florida. Results Modeling of missing data and imputing missing values can affect the identified periods of extreme heat, through the missing data itself or through the computed thresholds. The differences observed are related to the amount of missingness during June, July, and August, the warmest months of the warm season (April through September). Conclusions Missing data considerations are important when defining periods of extreme heat. Spatio-temporal methods are recommended for data imputation. A heat wave definition that incorporates information from all monitors is advised. PMID:26619198

  7. A Study of Alfven Wave Propagation and Heating the Chromosphere

    NASA Astrophysics Data System (ADS)

    Tu, J.; Song, P.

    2013-12-01

    Alfven wave propagation, reflection and heating of the solar atmosphere are studied for a one-dimensional solar atmosphere by self-consistently solving plasma and neutral fluid equations and Maxwell's equations with incorporation of the Hall effect, strong electron-neutral, electron-ion, and ion-neutral collisions. The governing equations are very stiff because of the strong coupling between the charged and neutral fluids. We have developed a numerical model based on an implicit backward difference formula (BDF2) of second order accuracy both in time and space to overcome the stiffness. A non-reflecting boundary condition is applied to the top boundary of the simulation domain so that the wave reflection within the domain due to the density gradient can be unambiguously determined. It is shown that the Alfven waves are partially reflected throughout the chromosphere. The reflection is increasingly stronger at higher altitudes and the strongest reflection occurs at the transition region. The waves are damped in the lower chromosphere dominantly through Joule dissipation due to electron collisions with neutrals and ions. The heating resulting from the wave damping is strong enough to balance the radiation energy loss for the quiet chromosphere. The collisional dissipation of the Alfven waves in the weakly collisional corona is negligible. The heating rates are larger for weaker background magnetic fields. In addition, higher frequency waves are subject to heavier damping. There is an upper cutoff frequency, depending on the background magnetic field, above which the waves are completely damped. At the frequencies below which the waves are not strongly damped, the waves may be strongly reflected at the transition region. The reflected waves interacting with the upward propagating waves may produce power at their double frequencies, which leads to more damping. Due to the reflection and damping, the energy flux of the waves transmitted to the corona is one order of

  8. Direct heating rates associated with gravity wave saturation

    NASA Astrophysics Data System (ADS)

    Becker, Erich

    2004-04-01

    Analysis of filtering out subscale motions is applied for internal gravity waves. This leads to a new perspective of the planetary-scale sensible heat budget of the upper mesosphere/lower thermosphere. In line with previous results of Becker and Schmitz, the present paper recapitulates that the dissipation of gravity wave kinetic energy and the local adiabatic conversion of mean enthalpy into gravity wave kinetic energy cannot be neglected, and that the net effect of both cools the upper mesosphere/lower thermosphere. In addition, the importance of the wave entropy flux-an effect which is ignored in customary gravity wave parameterizations for global circulation models-is stressed. We show that, when evaluated on the basis of Lindzen's saturation assumption, the wave entropy flux convergence behaves like a vertical diffusion of the mean stratification, where the wave-induced diffusion coefficient is involved with a Prandtl number of 2. This result imposes an upper bound of 2 for the effective Prandtl number which scales the combined entropy flux owing to turbulence and gravity waves. The direct heating rates generated by gravity wave saturation are assessed quantitatively, using an idealized general circulation model completed by a Lindzen-type gravity wave parameterization.

  9. Heat waves, aging, and human cardiovascular health.

    PubMed

    Kenney, W Larry; Craighead, Daniel H; Alexander, Lacy M

    2014-10-01

    This brief review is based on a President's Lecture presented at the Annual Meeting of the American College of Sports Medicine in 2013. The purpose of this review was to assess the effects of climate change and consequent increases in environmental heat stress on the aging cardiovascular system. The earth's average global temperature is slowly but consistently increasing, and along with mean temperature changes come increases in heat wave frequency and severity. Extreme passive thermal stress resulting from prolonged elevations in ambient temperature and prolonged physical activity in hot environments creates a high demand on the left ventricle to pump blood to the skin to dissipate heat. Even healthy aging is accompanied by altered cardiovascular function, which limits the extent to which older individuals can maintain stroke volume, increase cardiac output, and increase skin blood flow when exposed to environmental extremes. In the elderly, the increased cardiovascular demand during heat waves is often fatal because of increased strain on an already compromised left ventricle. Not surprisingly, excess deaths during heat waves 1) occur predominantly in older individuals and 2) are overwhelmingly cardiovascular in origin. Increasing frequency and severity of heat waves coupled with a rapidly growing at-risk population dramatically increase the extent of future untoward health outcomes.

  10. HEAT WAVES, AGING, AND HUMAN CARDIOVASCULAR HEALTH

    PubMed Central

    Kenney, W. Larry; Craighead, Daniel H.; Alexander, Lacy M.

    2014-01-01

    This brief review is based on a President’s Lecture presented at the Annual Meeting of the American College of Sports Medicine in 2013. The purpose of this review is to assess the effects of climate change and consequent increases in environmental heat stress on the aging cardiovascular system. The earth’s average global temperature is slowly but consistently increasing, and along with mean temperature changes come increases in heat wave frequency and severity. Extreme passive thermal stress resulting from prolonged elevations in ambient temperature, as well as prolonged physical activity in hot environments, creates a high demand on the left ventricle to pump blood to the skin to dissipate heat. Even healthy aging is accompanied by altered cardiovascular function, which limits the extent to which older individuals can maintain stroke volume, increase cardiac output, and increase skin blood flow when exposed to environmental extremes. In the elderly, the increased cardiovascular demand during heat waves is often fatal due to increased strain on an already compromised left ventricle. Not surprisingly, excess deaths during heat waves 1) occur predominantly in older individuals and 2) are overwhelmingly cardiovascular in origin. Increasing frequency and severity of heat waves coupled with a rapidly growing at-risk population dramatically increases the extent of future untoward health outcomes. PMID:24598696

  11. On the physics of waves in the solar atmosphere: Wave heating and wind acceleration

    NASA Technical Reports Server (NTRS)

    Musielak, Z. E.

    1993-01-01

    This paper presents work performed on the generation and physics of acoustic waves in the solar atmosphere. The investigators have incorporated spatial and temporal turbulent energy spectra in a newly corrected version of the Lighthill-Stein theory of acoustic wave generation in order to calculate the acoustic wave energy fluxes generated in the solar convective zone. The investigators have also revised and improved the treatment of the generation of magnetic flux tube waves, which can carry energy along the tubes far away from the region of their origin, and have calculated the tube energy fluxes for the sun. They also examine the transfer of the wave energy originated in the solar convective zone to the outer atmospheric layers through computation of wave propagation and dissipation in highly nonhomogeneous solar atmosphere. These waves may efficiently heat the solar atmosphere and the heating will be especially significant in the chromospheric network. It is also shown that the role played by Alfven waves in solar wind acceleration and coronal hole heating is dominant. The second part of the project concerned investigation of wave propagation in highly inhomogeneous stellar atmospheres using an approach based on an analytic tool developed by Musielak, Fontenla, and Moore. In addition, a new technique based on Dirac equations has been developed to investigate coupling between different MHD waves propagating in stratified stellar atmospheres.

  12. Inductance of rf-wave-heated plasmas.

    PubMed

    Farshi, E; Todo, Y

    2003-03-14

    The inductance of rf-wave-heated plasmas is derived. This inductance represents the inductance of fast electrons located in a plateau during their acceleration due to electric field or deceleration due to collisions and electric field. This inductance has been calculated for small electric fields from the two-dimensional Fokker-Planck equation as the flux crossing the surface of critical energy mv(2)(ph)/2 in the velocity space. The new expression may be important for radio-frequency current drive ramp-up, current drive efficiency, current profile control, and so on in tokamaks. This inductance may be incorporated into transport codes that study plasma heating by rf waves.

  13. Heat, Heat Waves, and Hospital Admissions among the Elderly in the United States, 1992–2006

    PubMed Central

    Zanobetti, Antonella; Schwartz, Joel D.; Wellenius, Gregory A.; O’Neill, Marie S.

    2014-01-01

    Background: Heat-wave frequency, intensity, and duration are increasing with global climate change. The association between heat and mortality in the elderly is well documented, but less is known regarding associations with hospital admissions. Objectives: Our goal was to determine associations between moderate and extreme heat, heat waves, and hospital admissions for nonaccidental causes among Medicare beneficiaries ≥ 65 years of age in 114 cities across five U.S. climate zones. Methods: We used Medicare inpatient billing records and city-specific data on temperature, humidity, and ozone from 1992 through 2006 in a time-stratified case-crossover design to estimate the association between hospitalization and moderate [90th percentile of apparent temperature (AT)] and extreme (99th percentile of AT) heat and heat waves (AT above the 95th percentile over 2–8 days). In sensitivity analyses, we additionally considered confounding by ozone and holidays, different temperature metrics, and alternate models of the exposure–response relationship. Results: Associations between moderate heat and hospital admissions were minimal, but extreme heat was associated with a 3% (95% CI: 2%, 4%) increase in all-cause hospital admissions over the subsequent 8 days. In cause-specific analyses, extreme heat was associated with increased hospitalizations for renal (15%; 95% CI: 9%, 21%) and respiratory (4%; 95% CI: 2%, 7%) diseases, but not for cardiovascular diseases. An added heat-wave effect was observed for renal and respiratory admissions. Conclusion: Extreme heat is associated with increased hospital admissions, particularly for renal causes, among the elderly in the United States. Citation: Gronlund CJ, Zanobetti A, Schwartz JD, Wellenius GA, O’Neill MS. 2014. Heat, heat waves, and hospital admissions among the elderly in the United States, 1992–2006. Environ Health Perspect 122:1187–1192; http://dx.doi.org/10.1289/ehp.1206132 PMID:24905551

  14. On the Definition of a Heat Wave.

    NASA Astrophysics Data System (ADS)

    Robinson, Peter J.

    2001-04-01

    Heat waves are a major cause of weather-related deaths. With the current concern for global warming it is reasonable to suppose that they may increase in frequency, severity, duration, or areal extent in the future. However, in the absence of an adequate definition of a heat wave, it is impossible to assess either changes in the past or possible consequences for the future. A set of definitions is proposed here, based on the criteria for heat stress forecasts developed by the National Weather Service (NWS). Watches or warnings are issued when thresholds of daytime high and nighttime low heat index (Hi) values are exceeded for at least two consecutive days. The heat index is a combination of ambient temperature and humidity that approximates the environmental aspect of the thermal regime of a human body, with the NWS thresholds representing a generalized estimate of the onset of physiological stress. These thresholds cannot be applied directly nationwide. In hot and humid regions, physical, social, and cultural adaptations will require that the thresholds be set higher to ensure that only those events perceived as stressful are identified. In other, cooler, areas the NWS criteria may never be reached even though unusually hot events may be perceived as heat waves. Thus, it is likely that a similar number of perceived heat events will occur in all regions, with the thresholds varying regionally. Hourly Hi for 178 stations in the coterminous United States was analyzed for the 1951-90 period to determine appropriate threshold criteria. Use of the NWS criteria alone indicated that much of the nation had less than three heat waves per decade, and this value was adopted as the baseline against which to establish suitable thresholds. For all areas, a percentile threshold approach was tested. Using all available data, daytime high and nighttime low thresholds were established separately for each specific percentile. Heat waves were treated as occurring when conditions

  15. Heat waves and warm periods in Slovakia

    NASA Astrophysics Data System (ADS)

    Faško, Pavel; Bochníček, Oliver; Markovič, Ladislav; Švec, Marek

    2016-04-01

    The scenarios of climate change caused by human activity show that frequency of occurrence and extent of heat waves in the interior of Europe is increasing. Among the most exposed regions in this regard should the area of southeastern and eastern Austria and south-western Slovakia. The relatively faster increase in the number of heat waves in this area is related also to potential desertification in this region just east of the Alps, since during summer, weather fronts advancing from the west are consequently losing their original features and moderating influence. Summer weather patterns for this area should in the future more closely remind climate typical for some inland areas of southwestern, southern and southeastern Europe. A certain shift of climate zones from south to north should thus modify future climate and Slovakia. Despite the complex natural conditions the existing trends derived from results of meteorological measurements and observations are clear and they confirm warming of climate in this region. Observations and measurements in the recent years of the 21st century confirm, that heat waves are no longer rare phenomenon during summer, but are systematically appearing even in colder regions of northern Slovakia. What is very remarkable and will be necessary to pay more attention to, is the fact that these heat waves are expanding into previously unaffected areas, associated with the lack of rainfall and drought, on larger regional scale. In this study heat wave periods and individual heat events and days are statistically identified in the time series characteristics of air temperature at selected meteorological stations for the period from the mid-20th century until 2015, in case of available historical data even for longer period.

  16. Extreme heat changes post-heat wave community reassembly

    PubMed Central

    Seifert, Linda I; Weithoff, Guntram; Vos, Matthijs

    2015-01-01

    Climate forecasts project further increases in extremely high-temperature events. These present threats to biodiversity, as they promote population declines and local species extinctions. This implies that ecological communities will need to rely more strongly on recovery processes, such as recolonization from a meta-community context. It is poorly understood how differences in extreme event intensity change the outcome of subsequent community reassembly and if such extremes modify the biotic environment in ways that would prevent the successful re-establishment of lost species. We studied replicated aquatic communities consisting of algae and herbivorous rotifers in a design that involved a control and two different heat wave intensity treatments (29°C and 39°C). Animal species that suffered heat-induced extinction were subsequently re-introduced at the same time and density, in each of the two treatments. The 39°C treatment led to community closure in all replicates, meaning that a previously successful herbivore species could not re-establish itself in the postheat wave community. In contrast, such closure never occurred after a 29°C event. Heat wave intensity determined the number of herbivore extinctions and strongly affected algal relative abundances. Re-introduced herbivore species were thus confronted with significantly different food environments. This ecological legacy generated by heat wave intensity led to differences in the failure or success of herbivore species re-introductions. Reassembly was significantly more variable, and hence less predictable, after an extreme heat wave, and was more canalized after a moderate one. Our results pertain to relatively simple communities, but they suggest that ecological legacies introduced by extremely high-temperature events may change subsequent ecological recovery and even prevent the successful re-establishment of lost species. Knowing the processes promoting and preventing ecological recovery is crucial

  17. Extreme heat changes post-heat wave community reassembly.

    PubMed

    Seifert, Linda I; Weithoff, Guntram; Vos, Matthijs

    2015-06-01

    Climate forecasts project further increases in extremely high-temperature events. These present threats to biodiversity, as they promote population declines and local species extinctions. This implies that ecological communities will need to rely more strongly on recovery processes, such as recolonization from a meta-community context. It is poorly understood how differences in extreme event intensity change the outcome of subsequent community reassembly and if such extremes modify the biotic environment in ways that would prevent the successful re-establishment of lost species. We studied replicated aquatic communities consisting of algae and herbivorous rotifers in a design that involved a control and two different heat wave intensity treatments (29°C and 39°C). Animal species that suffered heat-induced extinction were subsequently re-introduced at the same time and density, in each of the two treatments. The 39°C treatment led to community closure in all replicates, meaning that a previously successful herbivore species could not re-establish itself in the postheat wave community. In contrast, such closure never occurred after a 29°C event. Heat wave intensity determined the number of herbivore extinctions and strongly affected algal relative abundances. Re-introduced herbivore species were thus confronted with significantly different food environments. This ecological legacy generated by heat wave intensity led to differences in the failure or success of herbivore species re-introductions. Reassembly was significantly more variable, and hence less predictable, after an extreme heat wave, and was more canalized after a moderate one. Our results pertain to relatively simple communities, but they suggest that ecological legacies introduced by extremely high-temperature events may change subsequent ecological recovery and even prevent the successful re-establishment of lost species. Knowing the processes promoting and preventing ecological recovery is crucial

  18. Extreme heat changes post-heat wave community reassembly.

    PubMed

    Seifert, Linda I; Weithoff, Guntram; Vos, Matthijs

    2015-06-01

    Climate forecasts project further increases in extremely high-temperature events. These present threats to biodiversity, as they promote population declines and local species extinctions. This implies that ecological communities will need to rely more strongly on recovery processes, such as recolonization from a meta-community context. It is poorly understood how differences in extreme event intensity change the outcome of subsequent community reassembly and if such extremes modify the biotic environment in ways that would prevent the successful re-establishment of lost species. We studied replicated aquatic communities consisting of algae and herbivorous rotifers in a design that involved a control and two different heat wave intensity treatments (29°C and 39°C). Animal species that suffered heat-induced extinction were subsequently re-introduced at the same time and density, in each of the two treatments. The 39°C treatment led to community closure in all replicates, meaning that a previously successful herbivore species could not re-establish itself in the postheat wave community. In contrast, such closure never occurred after a 29°C event. Heat wave intensity determined the number of herbivore extinctions and strongly affected algal relative abundances. Re-introduced herbivore species were thus confronted with significantly different food environments. This ecological legacy generated by heat wave intensity led to differences in the failure or success of herbivore species re-introductions. Reassembly was significantly more variable, and hence less predictable, after an extreme heat wave, and was more canalized after a moderate one. Our results pertain to relatively simple communities, but they suggest that ecological legacies introduced by extremely high-temperature events may change subsequent ecological recovery and even prevent the successful re-establishment of lost species. Knowing the processes promoting and preventing ecological recovery is crucial

  19. Chromospheric heating by acoustic shock waves

    NASA Technical Reports Server (NTRS)

    Jordan, Stuart D.

    1993-01-01

    Work by Anderson & Athay (1989) suggests that the mechanical energy required to heat the quiet solar chromosphere might be due to the dissipation of weak acoustic shocks. The calculations reported here demonstrate that a simple picture of chromospheric shock heating by acoustic waves propagating upward through a model solar atmosphere, free of both magnetic fields and local inhomogeneities, cannot reproduce their chromospheric model. The primary reason is the tendency for vertically propagating acoustic waves in the range of allowed periods to dissipate too low in the atmosphere, providing insufficient residual energy for the middle chromosphere. The effect of diverging magnetic fields and the corresponding expanding acoustic wavefronts on the mechanical dissipation length is then discussed as a means of preserving a quasi-acoustic heating hypothesis. It is argued that this effect, in a canopy that overlies the low chromosphere, might preserve the acoustic shock hypothesis consistent with the chromospheric radiation losses computed by Anderson & Athay.

  20. Eurasian Heat Waves: Mechanisms and Predictability

    NASA Technical Reports Server (NTRS)

    Wang, Hailan; Schubert, Siegfried; Koster, Randal; Suarez, Max

    2012-01-01

    This study uses the NASA MERRA reanalysis and GEOS 5 model simulations to examine the causes of Eurasian heat waves including the recent extreme events that occurred in Europe during 2003 and in Russia during 2010. The focus is on the warm season and the part of the Eurasian continent that extends north of about 40oN, or roughly to the north of the mean upper tropospheric jet stream. The results show that such extreme events are an amplification of natural patterns of atmospheric variability that develop over the Eurasian continent as a result of internal atmospheric forcing. The amplification occurs when the wave occasionally becomes locked in place for several weeks to months resulting in extreme heat and drying with the location depending on the phase of the upper atmospheric wave. An ensemble of very long GEOS-S model simulations (spanning the 20th century) forced with observed SST and greenhouse gases show that the model is capable of generating very similar heat waves, and that they have become more intense in the last thirty years as a result of the overall warming of the Asian continent. Sensitivity experiments with perturbed initial conditions indicate that these events have limited predictability.

  1. Progressive wave tube facility with additional capabilities

    NASA Astrophysics Data System (ADS)

    Lieberman, Paul; Bocksruker, Ron; Pilgram, Mark; Vallance, Charles

    1993-01-01

    The design and development of a new acoustic progressive wave tube facility was required to test the Titan IV rocket engine. Because of the large 6 feet diameter of the nozzle closure, circular shape, high over-all sound pressure level (OASPL), and high sound pressure levels (SPLs) above 1000 Hz, the acoustic environmental tests required consideration of a custom built facility. This paper describes a new oscillating supersonic shock generator (OSSG) for developing the high OASPL, for developing the high SPLs at above 1000 Hz, and for use with a conventional acoustic modulator. Also, the new OSSG permits impedance matching to the test volume annulus via the special geometry of the annular space between the elliptical containment domes upstream of the test volume annulus. A test annulus gap that is too small causes the test article to vibrate with a severe damping imposed by the pumping of trapped air in the annulus, and too large a gap reduces the OASPL. Consideration is given to tuning the axial and circumferential resonance frequencies of the annulus test space so that there is no coincidence with the principal resonant modes of the test structure. Also consideration is given to establishing the reverberant versus propagating modes of the test annulus.

  2. Summer heat waves over western Turkey between 1965 and 2006

    NASA Astrophysics Data System (ADS)

    Unal, Yurdanur Sezginer; Tan, Elcin; Mentes, S. Sibel

    2013-04-01

    Global warming is one of the greatest environmental, economic, and social threats in the world. There are many assessments to estimate climate variability over many regions. A change in the Earth's surface temperature leads to increase in extreme temperature events, which are harmful to the ecosystem, and moreover, they create danger on human health. In this study, we have selected the western part of Turkey as the study area, since climate change projections for Turkey point out that the highest temperature change can be expected on this region during summer, and the Turkish population is very dense here to be affected by extreme events. We have used apparent temperatures to define the heat waves which we have determined their frequencies for the summer months (June-August) of 1965-2006. Since the regional comparisons of station results are intended, we selected the 90th percentile value for each station as a threshold value to be used in the delineation of heat waves. Then, the number of heat waves is determined by imposing the constraint that apparent temperatures stay above the threshold value at least for three consecutive days. Then, the changes in the number of hot days and heat waves and also their durations are analyzed by using the linear least square method. We have found that the number of hot days, heat waves, and heat wave durations is increased between 1965 and 2006 on the western part of Turkey. Additionally, their rate of change is larger within the last decade and extremes are frequently observed after 1998. Regional distributions show that the tendency of the number of heat wave events increases towards the southern latitudes of the domain. Moreover, we investigated the relationship between the number of hot days and the sea surface temperatures of the Mediterranean Sea and Black Sea. Correlation analyses are carried out by the number of hot days and averaged sea surface temperatures on the regions of the western, central, and eastern

  3. The urban heat island and its impact on heat waves and human health in Shanghai.

    PubMed

    Tan, Jianguo; Zheng, Youfei; Tang, Xu; Guo, Changyi; Li, Liping; Song, Guixiang; Zhen, Xinrong; Yuan, Dong; Kalkstein, Adam J; Li, Furong

    2010-01-01

    With global warming forecast to continue into the foreseeable future, heat waves are very likely to increase in both frequency and intensity. In urban regions, these future heat waves will be exacerbated by the urban heat island effect, and will have the potential to negatively influence the health and welfare of urban residents. In order to investigate the health effects of the urban heat island (UHI) in Shanghai, China, 30 years of meteorological records (1975-2004) were examined for 11 first- and second-order weather stations in and around Shanghai. Additionally, automatic weather observation data recorded in recent years as well as daily all-cause summer mortality counts in 11 urban, suburban, and exurban regions (1998-2004) in Shanghai have been used. The results show that different sites (city center or surroundings) have experienced different degrees of warming as a result of increasing urbanization. In turn, this has resulted in a more extensive urban heat island effect, causing additional hot days and heat waves in urban regions compared to rural locales. An examination of summer mortality rates in and around Shanghai yields heightened heat-related mortality in urban regions, and we conclude that the UHI is directly responsible, acting to worsen the adverse health effects from exposure to extreme thermal conditions.

  4. On the construction of heat wave in symmetric case

    NASA Astrophysics Data System (ADS)

    Kazakov, A. L.; Lempert, A. A.

    2016-06-01

    A nonlinear second-order parabolic equation with two variables is considered. Under additional conditions, this equation can be interpreted as the porous medium equation in case of dependence of the unknown function on two variables: time and distance from the origin. The equation has a wide variety of applications in continuum mechanics, for example, it is applicable for mathematical modeling of filtration of ideal polytropic gas in porous media or heat conduction. The authors deal with a special solutions which are usually called heat waves. A special feature of such solution is that it consists of two continuously joined solutions. The first of them is trivial and the second one is nonnegative. The heat wave solution can have discontinuous derivatives on the line of joint which is called the front of heat wave, i.e. smoothness of the solution, generally speaking, is broken. The most natural problem which has such solutions is the so-called “the Sakharov problem of the initiation of a heat wave”. New solutions of the problem in the form of multiple power series for physical variables are constructed. The coefficients of the series are obtained from tridiagonal systems of linear algebraic equations. Herewith, the elements of matrices of this systems depend on the matrix order and the condition of the diagonal dominance is not fulfilled. The recurrent formulas for the coefficients are suggested.

  5. Development of a spinning wave heat engine

    NASA Technical Reports Server (NTRS)

    Zinn, B. T.; Powell, E. A.; Hubbartt, J. E.

    1982-01-01

    A theoretical analysis and an experimental investigation were conducted to assess the feasibility of developing a spinning wave heat engine. Such as engine would utilize a large amplitude traveling acoustic wave rotating around a cylindrica chamber, and it should not suffer from the inefficiency, noise, and intermittent thrust which characterizes pulse jet engines. The objective of this investigation was to determine whether an artificially driven large amplitude spinning transverse wave could induce a steady flow of air through the combustion chamber under cold flow conditions. In the theoretical analysis the Maslen and Moore perturbation technique was extended to study flat cylinders (pancake geometry) with completely open side walls and a central opening. In the parallel experimental study, a test moel was used to determine resonant frequencies and radial pressure distributions, as well as oscillatory and steady flow velocities at the inner and outer peripheries. The experimental frequency was nearly the same as the theoretical acoustic value for a model of the same outer diameter but without a central hole. Although the theoretical analysis did not predict a steady velocity component, simulaneous measurements of hotwire and microphone responses have shown that the spinning wave pumps a mean flow radially outward through the cavity.

  6. Heat waves in the United States: definitions, patterns and trends.

    PubMed

    Smith, Tiffany T; Zaitchik, Benjamin F; Gohlke, Julia M

    2013-06-01

    High temperatures and heat waves are related but not synonymous concepts. Heat waves, generally understood to be acute periods of extreme warmth, are relevant to a wide range of stakeholders because of the impacts that these events have on human health and activities and on natural environments. Perhaps because of the diversity of communities engaged in heat wave monitoring and research, there is no single, standard definition of a heat wave. Experts differ in which threshold values (absolute versus relative), duration and ancillary variables to incorporate into heat wave definitions. While there is value in this diversity of perspectives, the lack of a unified index can cause confusion when discussing patterns, trends, and impacts. Here, we use data from the North American Land Data Assimilation System to examine patterns and trends in 15 previously published heat wave indices for the period 1979-2011 across the Continental United States. Over this period the Southeast region saw the highest number of heat wave days for the majority of indices considered. Positive trends (increases in number of heat wave days per year) were greatest in the Southeast and Great Plains regions, where more than 12 % of the land area experienced significant increases in the number of heat wave days per year for the majority of heat wave indices. Significant negative trends were relatively rare, but were found in portions of the Southwest, Northwest, and Great Plains.

  7. Heat waves in the United States: definitions, patterns and trends

    PubMed Central

    Zaitchik, Benjamin F.; Gohlke, Julia M.

    2012-01-01

    High temperatures and heat waves are related but not synonymous concepts. Heat waves, generally understood to be acute periods of extreme warmth, are relevant to a wide range of stakeholders because of the impacts that these events have on human health and activities and on natural environments. Perhaps because of the diversity of communities engaged in heat wave monitoring and research, there is no single, standard definition of a heat wave. Experts differ in which threshold values (absolute versus relative), duration and ancillary variables to incorporate into heat wave definitions. While there is value in this diversity of perspectives, the lack of a unified index can cause confusion when discussing patterns, trends, and impacts. Here, we use data from the North American Land Data Assimilation System to examine patterns and trends in 15 previously published heat wave indices for the period 1979–2011 across the Continental United States. Over this period the Southeast region saw the highest number of heat wave days for the majority of indices considered. Positive trends (increases in number of heat wave days per year) were greatest in the Southeast and Great Plains regions, where more than 12 % of the land area experienced significant increases in the number of heat wave days per year for the majority of heat wave indices. Significant negative trends were relatively rare, but were found in portions of the Southwest, Northwest, and Great Plains. PMID:23869115

  8. Heat Waves, Urban Vegetation, and Air Pollution

    NASA Astrophysics Data System (ADS)

    Churkina, G.; Grote, R.; Butler, T. M.

    2014-12-01

    Fast-track programs to plant millions of trees in cities around the world aim at the reduction of summer temperatures, increase carbon storage, storm water control, provision of space for recreation, as well as poverty alleviation. Although these multiple benefits speak positively for urban greening programs, the programs do not take into account how close human and natural systems are coupled in urban areas. Elevated temperatures together with anthropogenic emissions of air and water pollutants distinguish the urban system. Urban and sub-urban vegetation responds to ambient changes and reacts with pollutants. Neglecting the existence of this coupling may lead to unforeseen drawbacks of urban greening programs. The potential for emissions from urban vegetation combined with anthropogenic emissions to produce ozone has long been recognized. This potential increases under rising temperatures. Here we investigate how global change induced heat waves affect emissions of volatile organic compounds (VOC) from urban vegetation and corresponding ground-level ozone levels. We also quantify other ecosystem services provided by urban vegetation (e.g., cooling and carbon storage) and their sensitivity to climate change. In this study we use Weather Research and Forecasting Model with coupled atmospheric chemistry (WRF-CHEM) to quantify these feedbacks in Berlin, Germany during the heat waves in 2003 and 2006. We highlight the importance of the vegetation for urban areas under changing climate and discuss associated tradeoffs.

  9. Determining Heat Waves from Observations and COSMO-CLM Simulations in Istanbul

    NASA Astrophysics Data System (ADS)

    Yuruk, Cemre; Unal, Yurdanur; Irem Bilgen, Simge; Topcu, Sema; Mentes, Sibel

    2016-04-01

    Climate change has crucial effects on cities and especially for informal settlements, urban poor and other vulnerable groups by influencing human health, assets and livelihoods. These impacts directly result from the variations in temperature and precipitation, and emergence of heat waves, droughts, floods and fires (IPCC, 2014). Summertime episodes with extremely high air temperatures which last for several days or longer are addressed to as heat waves and affect the weather and climate in the globe. The aim of this study is to analyze the occurrence of heat waves in terms of quantity, duration and frequency and also to evaluate the accuracy of the COSMO-CLM (CCLM) model coupled with MPI-ESM-LR in reproducing the characteristics of heat waves in Istanbul. The summer maximum temperatures of six Turkish State Meteorological Service (TSMS) stations are selected between 1960 and 2013 to estimate the characteristics of heat waves in Istanbul. We define the heat wave if the maximum temperatures exceed a threshold value for at least three consecutive days. The threshold value is determined as 30.5 °C from the 90th percentile of all six station's observations. Then it is used in the detection of the hot days, heat waves and their durations. The results show that not only the number of heat waves but also duration of heat waves increase towards the end of the study period. Especially, a significant increase in heat wave events is evident after 1990s. An example of this situation is observed in a Kilyos station located northern part of the city. Kilyos experiences only one heat wave in the beginning of 1970s whereas the number of heat waves increases in years and reaches to the maximum value of 5 in 2000. Furthermore, Kartal as an urban area in the Asian side of the city, exhibits highest heat wave duration with 18 consecutive days in 1998. In addition to station data analyses, the local climate of Istanbul and its vicinity is simulated by CCLM model with approximately 3

  10. Spatial analysis of the effect of the 2010 heat wave on stroke mortality in Nanjing, China.

    PubMed

    Chen, Kai; Huang, Lei; Zhou, Lian; Ma, Zongwei; Bi, Jun; Li, Tiantian

    2015-01-01

    To examine the spatial variation of stroke mortality risk during heat wave, we collected 418 stroke mortality cases with permanent addresses for a severe heat wave (July 28-August 15, 2010) and 624 cases for the reference period (July 29-August 16, 2009 and July 27-August 14, 2011) in Nanjing, China. Generalized additive models were used to explore the association between location and stroke mortality risk during the heat wave while controlling individual-level risk factors. Heat wave vulnerability was then applied to explain the possible spatial variations of heat-wave-related mortality risk. The overall risk ratio (95% confidence intervals) of stroke mortality due to the heat wave in Nanjing was 1.34 (1.21 to 1.47). Geolocation was found to be significantly associated with the heat-wave-related stroke mortality risk. Using alternative reference periods generated similar results. A district-level risk assessment revealed similar spatial patterns. The highest stroke mortality risk observed in Luhe district was due to the combination of high heat exposure and high vulnerability. Our findings provide evidence that stroke mortality risk is higher in rural areas during heat waves and that these areas require future interventions to reduce vulnerability. PMID:26034864

  11. Spatial analysis of the effect of the 2010 heat wave on stroke mortality in Nanjing, China

    PubMed Central

    Chen, Kai; Huang, Lei; Zhou, Lian; Ma, Zongwei; Bi, Jun; Li, Tiantian

    2015-01-01

    To examine the spatial variation of stroke mortality risk during heat wave, we collected 418 stroke mortality cases with permanent addresses for a severe heat wave (July 28–August 15, 2010) and 624 cases for the reference period (July 29–August 16, 2009 and July 27–August 14, 2011) in Nanjing, China. Generalized additive models were used to explore the association between location and stroke mortality risk during the heat wave while controlling individual-level risk factors. Heat wave vulnerability was then applied to explain the possible spatial variations of heat-wave-related mortality risk. The overall risk ratio (95% confidence intervals) of stroke mortality due to the heat wave in Nanjing was 1.34 (1.21 to 1.47). Geolocation was found to be significantly associated with the heat-wave-related stroke mortality risk. Using alternative reference periods generated similar results. A district-level risk assessment revealed similar spatial patterns. The highest stroke mortality risk observed in Luhe district was due to the combination of high heat exposure and high vulnerability. Our findings provide evidence that stroke mortality risk is higher in rural areas during heat waves and that these areas require future interventions to reduce vulnerability. PMID:26034864

  12. Dynamical effects of vegetation on the 2003 summer heat waves

    NASA Astrophysics Data System (ADS)

    Stéfanon, M.

    2012-04-01

    Dynamical effects of vegetation on the 2003 summer heat waves Marc Stéfanon(1), Philippe Drobinski(1), Fabio D'Andrea(1), Nathalie de Noblet(2) (1) IPSL/LMD, France; (2) IPSL/LSCE, France The land surface model (LSM) in regional climate models (RCMs) plays a key role in energy and water exchanges between land and atmosphere. The vegetation can affect these exchanges through physical, biophysical and bio-geophysical mechanisms. It participates to evapo-transpiration process which determines the partitioning of net radiation between sensible and latent heat flux, through water evaporation from soil throughout the entire root system. For seasonal timescale leaf cover change induced leaf-area index (LAI) and albedo changes, impacting the Earth's radiative balance. In addition, atmospheric chemistry and carbon concentration has a direct effect on plant stomatal structure, the main exchange interface with the atmosphere. Therefore the surface energy balance is intimately linked to the carbon cycle and vegetation conditions and an accurate representation of the Earth's surface is required to improve the performance of RCMs. It is even more crucial for extreme events as heat waves and droughts which display highly nonlinear behaviour. If triggering of heat waves is determined by the large scale, local coupled processes over land can amplify or inhibit heat trough several feedback mechanism. One set of two simulation has been conducted with WRF, using different LSMs. They aim to study drought and vegetation effect on the dynamical and hydrological processes controlling the occurrence and life cycle of heat waves In the MORCE plateform, the dynamical global vegetation model (DGVM) ORCHIDEE is implemented in the atmospheric module WRF. ORCHIDEE is based on three different modules. The first module, called SECHIBA, describes the fast processes such as exchanges of energy and water between the atmosphere and the biosphere, and the soil water budget. The phenology and carbon

  13. Phenomenology and Thermodynamical Characteristics of West African Heat Waves

    NASA Astrophysics Data System (ADS)

    Barbier, J.; Guichard, F.; Couvreux, F.; Bouniol, D.; Roehrig, R.; Mougin, E.; Leauthaud, C.

    2015-12-01

    Most of the studies on heat waves focus on their occurrences in the USA, Europe, China and Australia. Only a few articles deal with heat waves over the Sahel, even though monthly maximum temperatures in this region can rise to up to 40°C before the arrival of the summer monsoon. The focus here is on identifying and comprehending the physical mechanisms involved in the occurrence and phenomenology of springtime heat waves over the Sahel. In order to analyse those physical mechanisms, a heat index based on synoptic and intra-seasonal changes was defined. This new detection method was applied separately to daily maximum and minimum temperatures, leading to heat indexes respectively called HWmax and HWmin. This separation matters because physical processes linked to these two temperatures are expected to differ: maximum temperature fluctuations may be connected to cloud-aerosol-induced changes in surface shortwave radiation, whereas the influence of atmospheric humidity may be predominant for the minimum temperature, via its impact on surface longwave fluxes during nightime. Using the ERA-Interim reanalysis over the period 1979-2014, a hundred heat waves per heat index have been detected, that is roughly three heat waves per year, of mean length 5 to 6 days. HWmax perceived heat waves from March to July whereas HWmin recorded heat waves from March to May only. The temperature and other dynamic and thermodynamic variables, as well as severity, were further analysed in order to provide the major heat wave properties, and to assess whether archetypes can be identified.Finally, the detected heat waves have been compared to those picked up by classical heat indexes like the NOAA index and quantile-based indexes. The differences between the heat waves identified with the ERA-Interim, ERA-40, MERRA and NCEP2 reanalyses, the observationally-based BEST data and those obtained with local data will also be discussed, in particular their fluctuations over the past decades.

  14. Wave-modified mean exothermic heating in the mesopause region

    NASA Technical Reports Server (NTRS)

    Hickey, Michael P.; Walterscheid, Richard L.

    1994-01-01

    We employ a model of wave-driven OH nightglow fluctuations to calculate the effects of gravity waves on the chemical exothermic heating due to reactions involving odd hydrogen and odd oxygen species in the mesopause region. Using a model based on time means and deviations from those means, it is demonstrated that gravity waves contribute to the time-average exothermic heating. The effect can be significant because the fractional fluctuations in minor species density can be substantially greater than the fractional fluctuation of the major gas density. Our calculations reveal that the waves mitigate the exothermic heating, demonstrating their potential importance in the heat budget of the mesopause region.

  15. California heat waves in the present and future

    NASA Astrophysics Data System (ADS)

    Gershunov, Alexander; Guirguis, Kristen

    2012-09-01

    Current and projected heat waves are examined over California and its sub-regions in observations and downscaled global climate model (GCM) simulations. California heat wave activity falls into two distinct types: (1) typically dry daytime heat waves and (2) humid nighttime-accentuated events (Type I and Type II, respectively). The four GCMs considered project Type II heat waves to intensify more with climate change than the historically characteristic Type I events, although both types are projected to increase. This trend is already clearly observed and simulated to various degrees over all sub-regions of California. Part of the intensification in heat wave activity is due directly to mean warming. However, when one considers non-stationarity in daily temperature variance, desert heat waves are expected to become progressively and relatively less intense while coastal heat waves are projected to intensify even relative to the background warming. This result generally holds for both types of heat waves across models. Given the high coastal population density and low acclimatization to heat, especially humid heat, this trend bodes ill for coastal communities, jeopardizing public health and stressing energy resources.

  16. Heat wave in Italy and hyperthermia syndrome.

    PubMed

    Barbieri, Alberto; Pinna, Cristina; Fruggeri, Luca; Biagioni, Emanuela; Campagna, Anselmo

    2006-08-01

    In the city of Modena, Italy, daily temperatures registered during the year 2003 showed a higher mean increase of 3 degrees C compared with the previous three years, with average temperature of 26.1 degrees C, compared with 22.8 degrees C. The reported ambient temperature was higher than 32.3 degrees C in 84% of the recorded days, and daily values exceeded 35.1 degrees C in 62% of the days. During the summer, four heat waves occurred (June 11-15, July 21-23, August 3-15 and August 17-24). Nine patients affected by hyperthermia syndrome with a mean body temperature of 41.4 +/- 1.3 degrees C were admitted to the Intensive Care Unit (ICU) of the Modena Teaching Hospital. Another patient with similar clinical features was not admitted to ICU, but to a general ward, and eventually died a few hours later. Mortality reached 80% and the mean survival time was 4.2 days with median values of one day. All patients except for one were admitted during one of the four above-mentioned heat waves, and in particular, 7 patients were admitted during the period from August 3rd to 15th. A common feature among 8 of the 10 patients was the chronic consumption of psychoactive drugs. According to these observations, it is important to identify a population at risk in case of bioclimatological alarm, to find prevention strategies. It is extremely important in patients with hyperthermia to lower body temperature levels in the early hours to influence the malignant evolution of this severe pathologic process. PMID:16929877

  17. THE ROLE OF TORSIONAL ALFVEN WAVES IN CORONAL HEATING

    SciTech Connect

    Antolin, P.; Shibata, K. E-mail: shibata@kwasan.kyoto-u.ac.j

    2010-03-20

    In the context of coronal heating, among the zoo of magnetohydrodynamic (MHD) waves that exist in the solar atmosphere, Alfven waves receive special attention. Indeed, these waves constitute an attractive heating agent due to their ability to carry over the many different layers of the solar atmosphere sufficient energy to heat and maintain a corona. However, due to their incompressible nature these waves need a mechanism such as mode conversion (leading to shock heating), phase mixing, resonant absorption, or turbulent cascade in order to heat the plasma. Furthermore, their incompressibility makes their detection in the solar atmosphere very difficult. New observations with polarimetric, spectroscopic, and imaging instruments such as those on board the Japanese satellite Hinode, or the Crisp spectropolarimeter of the Swedish Solar Telescope or the Coronal Multi-channel Polarimeter, are bringing strong evidence for the existence of energetic Alfven waves in the solar corona. In order to assess the role of Alfven waves in coronal heating, in this work we model a magnetic flux tube being subject to Alfven wave heating through the mode conversion mechanism. Using a 1.5 dimensional MHD code, we carry out a parameter survey varying the magnetic flux tube geometry (length and expansion), the photospheric magnetic field, the photospheric velocity amplitudes, and the nature of the waves (monochromatic or white-noise spectrum). The regimes under which Alfven wave heating produces hot and stable coronae are found to be rather narrow. Independently of the photospheric wave amplitude and magnetic field, a corona can be produced and maintained only for long (>80 Mm) and thick (area ratio between the photosphere and corona >500) loops. Above a critical value of the photospheric velocity amplitude (generally a few km s{sup -1}) the corona can no longer be maintained over extended periods of time and collapses due to the large momentum of the waves. These results establish several

  18. North Atlantic Ocean drivers of the 2015 European heat wave

    NASA Astrophysics Data System (ADS)

    Duchez, Aurélie; Frajka-Williams, Eleanor; Josey, Simon A.; Hirschi, Joël; Evans, Gwyn

    2016-04-01

    Major European heat waves have occurred on several occasions in the past two decades, including the summer of 2015, with dramatic socioeconomic impacts and in a globally warming world, heat waves are expected to become longer, more frequent and more intense. Nevertheless, our understanding of heat wave causes remains at a basic level, limiting the usefulness of event prediction. We show that 2015 was the most extreme heat wave in central Europe in the past 35 years. We find that the heat wave was preceded by cold mid-latitude North Atlantic Ocean surface temperatures, which contributed to its development. In order to explain the genesis of the cold ocean anomaly, we consider surface heat loss, ocean heat content and wind driven upwelling. The anomaly is primarily due to extreme ocean heat loss in the preceding two winters and re-emergent cold ocean water masses. Further analysis indicates that this ocean anomaly was a driver for the 2015 heat wave as it favoured a stationary position of the Jet Stream, which steered Atlantic cyclones away from central Europe towards northern Europe. The cold Atlantic anomaly was also present during the most devastating European heat waves since the 1980s indicating that it is a common factor in the development of these extreme events.

  19. Heat Wave Changes in the Eastern Mediterranean since 1960

    NASA Astrophysics Data System (ADS)

    Kuglitsch, Franz G.; Toreti, Andrea; Xoplaki, Elena; Della-Marta, Paul M.; Zerefos, Christos S.; Türkes, Murat; Luterbacher, Jürg

    2010-05-01

    Heat waves have discernible impacts on mortality and morbidity, infrastructure, agricultural resources, the retail industry, ecosystem and tourism and consequently affect human societies. A new definition of socially relevant heat waves is presented and applied to new data sets of high-quality homogenized daily maximum and minimum summer air temperature series from 246 stations in the eastern Mediterranean region (including Albania, Bosnia-Herzegovina, Bulgaria, Croatia, Cyprus, Greece, Israel, Romania, Serbia, Slovenia, Turkey). Changes in heat wave number, length and intensity between 1960 and 2006 are quantified. Daily temperature homogeneity analysis suggest that many instrumental measurements in the 1960s are warm-biased, correcting for these biases regionally averaged heat wave trends are up to 8% higher. We find significant changes across the western Balkans, southwestern and western Turkey, and along the southern Black Sea coastline. Since the 1960s, the mean heat wave intensity, heat wave length and heat wave number across the eastern Mediterranean region have increased by a factor 7.6 ±1.3, 7.5 ±1.3 and 6.2 ±1.1, respectively. These findings suggest that the heat wave increase in this region is higher than previously reported.

  20. Stochastic Ion Heating by the Lower-Hybrid Waves

    NASA Technical Reports Server (NTRS)

    Khazanov, G.; Tel'nikhin, A.; Krotov, A.

    2011-01-01

    The resonance lower-hybrid wave-ion interaction is described by a group (differentiable map) of transformations of phase space of the system. All solutions to the map belong to a strange attractor, and chaotic motion of the attractor manifests itself in a number of macroscopic effects, such as the energy spectrum and particle heating. The applicability of the model to the problem of ion heating by waves at the front of collisionless shock as well as ion acceleration by a spectrum of waves is discussed. Keywords: plasma; ion-cyclotron heating; shocks; beat-wave accelerator.

  1. Seasonal mean temperature changes control future heat waves

    NASA Astrophysics Data System (ADS)

    Argüeso, Daniel; Di Luca, Alejandro; Perkins-Kirkpatrick, Sarah E.; Evans, Jason P.

    2016-07-01

    Increased temperature will result in longer, more frequent, and more intense heat waves. Changes in temperature variability have been deemed necessary to account for future heat wave characteristics. However, this has been quantified only in Europe and North America, while the rest of the globe remains unexplored. Using late century global climate projections, we show that annual mean temperature increases is the key factor defining heat wave changes in most regions. We find that commonly studied areas are an exception rather than the standard and the mean climate change signal generally outweighs any influence from variability changes. More importantly, differences in warming across seasons are responsible for most of the heat wave changes and their consideration relegates the contribution of variability to a marginal role. This reveals that accurately capturing mean seasonal changes is crucial to estimate future heat waves and reframes our interpretation of future temperature extremes.

  2. Magnitude and frequency of heat and cold waves in recent decades: the case of South America

    NASA Astrophysics Data System (ADS)

    Ceccherini, Guido; Russo, Simone; Ameztoy, Iban; Romero, Claudia Patricia; Carmona-Moreno, Cesar

    2016-03-01

    In recent decades there has been an increase in magnitude and occurrence of heat waves and a decrease of cold waves, both of which may be related to the anthropogenic influence. This study describes the extreme temperature regime of heat waves and cold waves across South America over recent years (1980-2014). Temperature records come from the Global Surface Summary of the Day (GSOD), a climatological data set produced by the National Climatic Data Center that provides records of daily maximum and minimum temperatures acquired worldwide. The magnitude of heat waves and cold waves for each GSOD station are quantified on an annual basis by means of the Heat Wave Magnitude Index and the Cold Wave Magnitude Index. Results indicate an increase in intensity and in frequency of heat waves, especially in the last 10 years. Conversely, no significant changes are detected for cold waves. In addition, the trend of the annual temperature range (i.e. yearly mean of Tmax - yearly mean of Tmin) is positive - up to 1 °C per decade - over the extratropics and negative - up to 0.5 °C per decade - over the tropics.

  3. Magnitude and frequency of heat and cold waves in recent decades: the case of South America

    NASA Astrophysics Data System (ADS)

    Ceccherini, G.; Russo, S.; Ameztoy, I.; Romero, C. P.; Carmona-Moreno, C.

    2015-12-01

    In recent decades there has been an increase in magnitude and occurrence of heat waves and a decrease of cold waves which are possibly related to the anthropogenic influence (Solomon et al., 2007). This study describes the extreme temperature regime of heat waves and cold waves across South America over recent years (1980-2014). Temperature records come from the Global Surface Summary of the Day (GSOD), a climatological dataset produced by the National Climatic Data Center that provides records of daily maximum and minimum temperatures acquired worldwide. The magnitude of heat waves and cold waves for each GSOD station are quantified on annual basis by means of the Heat Wave Magnitude Index (Russo et al., 2014) and the Cold Wave Magnitude Index (CWMI, Forzieri et al., 2015). Results indicate an increase in intensity and in frequency of heat waves, with up to 75 % more events occurring only in the last 10 years. Conversely, no significant changes are detected for cold waves. In addition, the trend of the annual temperature range (i.e., yearly mean of Tmax - yearly mean of Tmin) is positive - up to 1 °C decade-1 - over the extra-tropics and negative - up to 0.5 °C decade-1 - over the tropic. This dichotomous behaviour indicates that the annual mean of Tmax is generally increasing more than the annual mean of Tmin in the extra-tropics and vice versa in the tropics.

  4. Hydromagnetic wave heating of the low-density interstellar medium

    NASA Technical Reports Server (NTRS)

    Ferriere, Katia M.; Zweibel, Ellen G.; Shull, J. Michael

    1988-01-01

    A simple model for supernova remnant sources of MHD waves is used to calculate the energy spectrum of waves in the intercloud medium and the heating rate resulting from their dissipation. Models of thermal phases of interstellar gas in ionization and thermal equilibrium are then constructed, and it is demonstrated that wave dissipation can be an important heating mechanism which can account for the observed high H I temperatures in low-density (intercloud) neutral gas.

  5. Trends of cold and heat waves in Serbia

    NASA Astrophysics Data System (ADS)

    Unkašević, Miroslava; Tošić, Ivana

    2014-05-01

    The series of the daily minimum and maximum temperatures at fifteen stations in Serbia were used to calculate the cold and warm spell duration indicators, from which the duration and severity of the cold and heat waves were estimated. The trend analysis for all seasons was presented using the data from 1949 to 2012. The most important result of this study is the significant decreasing trends in the frequency of cold waves and increasing trends of heat waves in Serbia. An analysis of the daily minimum temperatures almost at all meteorological stations revealed that the longest and most severe cold waves were observed in winter of 1956, spring of 1987, summer of 1962 and 1996, and during the autumn 1983 and 1988. The longest and most severe heat waves, based on the analysis of the daily maximum temperatures, were recorded in winter of 2007, spring of 2003, summer of 2012, and after 1989 during the autumn. The longest heat waves observed in 2012 did not reach the severity of the heat waves in 2007 at ten of fifteen stations. The obtained results indicated that the warming in Serbia was more related to increase in frequency of heat waves than to reduction in cold waves.

  6. Magnitude of extreme heat waves in present climate and their projection in a warming world

    NASA Astrophysics Data System (ADS)

    Russo, Simone; Dosio, Alessandro; Graversen, Rune G.; Sillmann, Jana; Carrao, Hugo; Dunbar, Martha B.; Singleton, Andrew; Montagna, Paolo; Barbola, Paulo; Vogt, Jürgen V.

    2014-11-01

    An extreme heat wave occurred in Russia in the summer of 2010. It had serious impacts on humans and natural ecosystems, it was the strongest recorded globally in recent decades and exceeded in amplitude and spatial extent the previous hottest European summer in 2003. Earlier studies have not succeeded in comparing the magnitude of heat waves across continents and in time. This study introduces a new Heat Wave Magnitude Index that can be compared over space and time. The index is based on the analysis of daily maximum temperature in order to classify the strongest heat waves that occurred worldwide during the three study periods 1980-1990, 1991-2001, and 2002-2012. In addition, multimodel ensemble outputs from the Coupled Model Intercomparison Project Phase 5 are used to project future occurrence and severity of heat waves, under different Representative Concentration Pathways, adopted by the Intergovernmental Panel on Climate Change for its Fifth Assessment Report (AR5). Results show that the percentage of global area affected by heat waves has increased in recent decades. Moreover, model predictions reveal an increase in the probability of occurrence of extreme and very extreme heat waves in the coming years, in particular, by the end of this century, under the most severe IPCC AR5 scenario, events of the same severity as that in Russia in the summer of 2010 will become the norm and are projected to occur as often as every 2 years for regions such as southern Europe, North America, South America, Africa, and Indonesia.

  7. Modifying Effect of Heat Waves on the Relationship between Temperature and Mortality

    PubMed Central

    2016-01-01

    Studies conducted to evaluate temporal trends of heat-related mortality have not considered the effects of heat waves; although it is known they can affect mortality and act as a modifying factor. After adjusting for long-term trends and seasonality, the effects of temperature on non-accidental deaths in Seoul and Busan (inland and coastal cities, respectively) were analyzed using a generalized additive model of Poisson distribution. We evaluated temporal trends of heat-related mortalities in four periods (1991-1995, 1996-2000, 2001-2005, and 2006-2012). The effects of temperature on mortality were evaluated according to the occurrence of a heat wave and results were compared in the two cities. The effect of temperature on mortality was the greatest in 1991-1995 in Seoul; no significant change was observed in Busan. When we stratified the study period by heat wave status, the risk increase in mortality was 15.9% per 1℃ during years with a heat wave in Seoul, which was much higher than 0.31% increase observed during years without a heat wave. On the other hand, Busan showed a linear relationship between temperature and mortality and no significant difference between years with or without a heat wave. Variations in the relationship between temperature and mortality could be misunderstood if heat waves are not considered. Furthermore, heterogeneity was found in the modifying effect of heat waves on heat-related mortality in inland and coastal cities. The findings of this study help understand relations between temperature and mortality. PMID:27134490

  8. Modifying Effect of Heat Waves on the Relationship between Temperature and Mortality.

    PubMed

    Lee, Won Kyung; Lee, Hye Ah; Park, Hyesook

    2016-05-01

    Studies conducted to evaluate temporal trends of heat-related mortality have not considered the effects of heat waves; although it is known they can affect mortality and act as a modifying factor. After adjusting for long-term trends and seasonality, the effects of temperature on non-accidental deaths in Seoul and Busan (inland and coastal cities, respectively) were analyzed using a generalized additive model of Poisson distribution. We evaluated temporal trends of heat-related mortalities in four periods (1991-1995, 1996-2000, 2001-2005, and 2006-2012). The effects of temperature on mortality were evaluated according to the occurrence of a heat wave and results were compared in the two cities. The effect of temperature on mortality was the greatest in 1991-1995 in Seoul; no significant change was observed in Busan. When we stratified the study period by heat wave status, the risk increase in mortality was 15.9% per 1℃ during years with a heat wave in Seoul, which was much higher than 0.31% increase observed during years without a heat wave. On the other hand, Busan showed a linear relationship between temperature and mortality and no significant difference between years with or without a heat wave. Variations in the relationship between temperature and mortality could be misunderstood if heat waves are not considered. Furthermore, heterogeneity was found in the modifying effect of heat waves on heat-related mortality in inland and coastal cities. The findings of this study help understand relations between temperature and mortality. PMID:27134490

  9. Climatic Influences on Indian and Pacific Ocean Heat Waves

    NASA Astrophysics Data System (ADS)

    Scannell, H. A.; England, M. H.; Sen Gupta, A.

    2014-12-01

    Large-scale ocean heat waves can be extremely damaging for both ecosystem functioning and fishery productivity. Unlike terrestrial heat waves, little work has been done to understand the dynamics of heat waves in sea surface temperature (SST). New high spatial and temporal resolution SST products now make it possible to investigate regions of persistent extreme anomalies in SST. Here we characterize the properties of Indian and Pacific Ocean heat waves and investigate how they are modulated by the dominant modes of Indo-Pacific climate variability. In particular, we investigate the influence of El Niño/Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) in preconditioning ocean heat waves. For the purposes of this study we define heat waves based on an index of cumulative SST 1ºC above the annual maximum with a geographic extent on the order of 105 square kilometers. We examine the prevalence of ocean heat waves during different phases of ENSO and the IOD, and explore the oceanic and atmospheric processes that give rise to these events.

  10. The heating of coronal loops by MHD waves

    NASA Technical Reports Server (NTRS)

    Davila, Joseph M.

    1988-01-01

    A detailed derivation of the MHD wave equation appropriate for solar coronal conditions is presented. Some general concepts are discussed regarding the propagation of MHD waves in regions where gradients in the Alfven speed exist. A solution of the ideal equation is discussed, and the ideal solution near the surface of the resonance layer is obtained. The dissipative solution is found and the matching between the ideal and dissipative solutions is demonstrated. The heating rate is calculated and the expression for the heating rate is used to estimate the wave amplitude which is necessary in the corona to explain the observed active region heating rate on the sun.

  11. Added effect of heat wave on mortality in Seoul, Korea

    NASA Astrophysics Data System (ADS)

    Lee, Won Kyung; Lee, Hye Ah; Lim, Youn Hee; Park, Hyesook

    2016-05-01

    A heat wave could increase mortality owing to high temperature. However, little is known about the added (duration) effect of heat wave from the prolonged period of high temperature on mortality and different effect sizes depending on the definition of heat waves and models. A distributed lag non-linear model with a quasi-Poisson distribution was used to evaluate the added effect of heat wave on mortality after adjusting for long-term and intra-seasonal trends and apparent temperature. We evaluated the cumulative relative risk of the added wave effect on mortality on lag days 0-30. The models were constructed using nine definitions of heat wave and two relationships (cubic spline and linear threshold model) between temperature and mortality to leave out the high temperature effect. Further, we performed sensitivity analysis to evaluate the changes in the effect of heat wave on mortality according to the different degrees of freedom for time trend and cubic spline of temperature. We found that heat wave had the added effect from the prolonged period of high temperature on mortality and it was considerable in the aspect of cumulative risk because of the lagged influence. When heat wave was defined with a threshold of 98th percentile temperature and ≥2, 3, and 4 consecutive days, mortality increased by 14.8 % (7.5-22.6, 95 % confidence interval (CI)), 18.1 % (10.8-26.0, 95 % CI), 18.1 % (10.7-25.9, 95 % CI), respectively, in cubic spline model. When it came to the definitions of 90th and 95th percentile, the risk increase in mortality declined to 3.7-5.8 % and 8.6-11.3 %, respectively. This effect was robust to the flexibility of the model for temperature and time trend, while the definitions of a heat wave were critical in estimating its relationship with mortality. This finding could help deepen our understanding and quantifying of the relationship between heat wave and mortality and select an appropriate definition of heat wave and temperature model in the future

  12. Added effect of heat wave on mortality in Seoul, Korea.

    PubMed

    Lee, Won Kyung; Lee, Hye Ah; Lim, Youn Hee; Park, Hyesook

    2016-05-01

    A heat wave could increase mortality owing to high temperature. However, little is known about the added (duration) effect of heat wave from the prolonged period of high temperature on mortality and different effect sizes depending on the definition of heat waves and models. A distributed lag non-linear model with a quasi-Poisson distribution was used to evaluate the added effect of heat wave on mortality after adjusting for long-term and intra-seasonal trends and apparent temperature. We evaluated the cumulative relative risk of the added wave effect on mortality on lag days 0-30. The models were constructed using nine definitions of heat wave and two relationships (cubic spline and linear threshold model) between temperature and mortality to leave out the high temperature effect. Further, we performed sensitivity analysis to evaluate the changes in the effect of heat wave on mortality according to the different degrees of freedom for time trend and cubic spline of temperature. We found that heat wave had the added effect from the prolonged period of high temperature on mortality and it was considerable in the aspect of cumulative risk because of the lagged influence. When heat wave was defined with a threshold of 98th percentile temperature and ≥2, 3, and 4 consecutive days, mortality increased by 14.8 % (7.5-22.6, 95 % confidence interval (CI)), 18.1 % (10.8-26.0, 95 % CI), 18.1 % (10.7-25.9, 95 % CI), respectively, in cubic spline model. When it came to the definitions of 90th and 95th percentile, the risk increase in mortality declined to 3.7-5.8 % and 8.6-11.3 %, respectively. This effect was robust to the flexibility of the model for temperature and time trend, while the definitions of a heat wave were critical in estimating its relationship with mortality. This finding could help deepen our understanding and quantifying of the relationship between heat wave and mortality and select an appropriate definition of heat wave and temperature model in the future

  13. Added effect of heat wave on mortality in Seoul, Korea.

    PubMed

    Lee, Won Kyung; Lee, Hye Ah; Lim, Youn Hee; Park, Hyesook

    2016-05-01

    A heat wave could increase mortality owing to high temperature. However, little is known about the added (duration) effect of heat wave from the prolonged period of high temperature on mortality and different effect sizes depending on the definition of heat waves and models. A distributed lag non-linear model with a quasi-Poisson distribution was used to evaluate the added effect of heat wave on mortality after adjusting for long-term and intra-seasonal trends and apparent temperature. We evaluated the cumulative relative risk of the added wave effect on mortality on lag days 0-30. The models were constructed using nine definitions of heat wave and two relationships (cubic spline and linear threshold model) between temperature and mortality to leave out the high temperature effect. Further, we performed sensitivity analysis to evaluate the changes in the effect of heat wave on mortality according to the different degrees of freedom for time trend and cubic spline of temperature. We found that heat wave had the added effect from the prolonged period of high temperature on mortality and it was considerable in the aspect of cumulative risk because of the lagged influence. When heat wave was defined with a threshold of 98th percentile temperature and ≥2, 3, and 4 consecutive days, mortality increased by 14.8 % (7.5-22.6, 95 % confidence interval (CI)), 18.1 % (10.8-26.0, 95 % CI), 18.1 % (10.7-25.9, 95 % CI), respectively, in cubic spline model. When it came to the definitions of 90th and 95th percentile, the risk increase in mortality declined to 3.7-5.8 % and 8.6-11.3 %, respectively. This effect was robust to the flexibility of the model for temperature and time trend, while the definitions of a heat wave were critical in estimating its relationship with mortality. This finding could help deepen our understanding and quantifying of the relationship between heat wave and mortality and select an appropriate definition of heat wave and temperature model in the future

  14. HEATING AND CURRENT DRIVE IN NSTX WITH ELECTRON BERNSTEIN WAVES AND HIGH HARMONIC FAST WAVES

    SciTech Connect

    Ram, Abhay K

    2010-06-14

    A suitable theoretical and computational framework for studying heating and current drive by electron Bernstein waves in the National Spherical Torus Experiment has been developed. This framework can also be used to study heating and current drive by electron Bernstein waves in spherical tori and other magnetic confinement devices. It is also useful in studying the propagation and damping of electron cyclotron waves in the International Thermonuclear Experimental Reactor

  15. The Source of Alfven Waves That Heat the Solar Corona

    NASA Technical Reports Server (NTRS)

    Ruzmaikin, A.; Berger, M. A.

    1998-01-01

    We suggest a source for high-frequency Alfven waves invoked in coronal heating and acceleration of the solar wind. The source is associated with small-scale magnetic loops in the chromospheric network.

  16. Low-Frequency Waves in HF Heating of the Ionosphere

    NASA Astrophysics Data System (ADS)

    Sharma, A. S.; Eliasson, B.; Milikh, G. M.; Najmi, A.; Papadopoulos, K.; Shao, X.; Vartanyan, A.

    2016-02-01

    Ionospheric heating experiments have enabled an exploration of the ionosphere as a large-scale natural laboratory for the study of many plasma processes. These experiments inject high-frequency (HF) radio waves using high-power transmitters and an array of ground- and space-based diagnostics. This chapter discusses the excitation and propagation of low-frequency waves in HF heating of the ionosphere. The theoretical aspects and the associated models and simulations, and the results from experiments, mostly from the HAARP facility, are presented together to provide a comprehensive interpretation of the relevant plasma processes. The chapter presents the plasma model of the ionosphere for describing the physical processes during HF heating, the numerical code, and the simulations of the excitation of low-frequency waves by HF heating. It then gives the simulations of the high-latitude ionosphere and mid-latitude ionosphere. The chapter also briefly discusses the role of kinetic processes associated with wave generation.

  17. Solid-State Additive Manufacturing for Heat Exchangers

    NASA Astrophysics Data System (ADS)

    Norfolk, Mark; Johnson, Hilary

    2015-03-01

    Energy densities in devices are increasing across many industries including power generation, high power electronics, manufacturing, and automotive. Increasingly, there is a need for very high efficiency thermal management devices that can pull heat out of a small area at higher and higher rates. Metal additive manufacturing (AM) technologies have the promise of creating parts with complex internal geometries required for integral thermal management. However, this goal has not been met due to constraints in fusion-based metal 3D printers. This work presents a new strategy for metal AM of heat exchangers using an ultrasonic sheet lamination approach.

  18. Solar coronal loop heating by cross-field wave transport

    NASA Technical Reports Server (NTRS)

    Amendt, Peter; Benford, Gregory

    1989-01-01

    Solar coronal arches heated by turbulent ion-cyclotron waves may suffer significant cross-field transport by these waves. Nonlinear processes fix the wave-propagation speed at about a tenth of the ion thermal velocity, which seems sufficient to spread heat from a central core into a large cool surrounding cocoon. Waves heat cocoon ions both through classical ion-electron collisions and by turbulent stochastic ion motions. Plausible cocoon sizes set by wave damping are in roughly kilometers, although the wave-emitting core may be only 100 m wide. Detailed study of nonlinear stabilization and energy-deposition rates predicts that nearby regions can heat to values intermediate between the roughly electron volt foot-point temperatures and the about 100 eV core, which is heated by anomalous Ohmic losses. A volume of 100 times the core volume may be affected. This qualitative result may solve a persistent problem with current-driven coronal heating; that it affects only small volumes and provides no way to produce the extended warm structures perceptible to existing instruments.

  19. Non-additive model for specific heat of electrons

    NASA Astrophysics Data System (ADS)

    Anselmo, D. H. A. L.; Vasconcelos, M. S.; Silva, R.; Mello, V. D.

    2016-10-01

    By using non-additive Tsallis entropy we demonstrate numerically that one-dimensional quasicrystals, whose energy spectra are multifractal Cantor sets, are characterized by an entropic parameter, and calculate the electronic specific heat, where we consider a non-additive entropy Sq. In our method we consider an energy spectra calculated using the one-dimensional tight binding Schrödinger equation, and their bands (or levels) are scaled onto the [ 0 , 1 ] interval. The Tsallis' formalism is applied to the energy spectra of Fibonacci and double-period one-dimensional quasiperiodic lattices. We analytically obtain an expression for the specific heat that we consider to be more appropriate to calculate this quantity in those quasiperiodic structures.

  20. Quantification and assessment of heat and cold waves in Novi Sad, Northern Serbia.

    PubMed

    Basarin, Biljana; Lukić, Tin; Matzarakis, Andreas

    2016-01-01

    Physiologically equivalent temperature (PET) has been applied to the analysis of heat and cold waves and human thermal conditions in Novi Sad, Serbia. A series of daily minimum and maximum air temperature, relative humidity, wind, and cloud cover was used to calculate PET for the investigated period 1949-2012. The heat and cold wave analysis was carried out on days with PET values exceeding defined thresholds. Additionally, the acclimatization approach was introduced to evaluate human adaptation to interannual thermal perception. Trend analysis has revealed the presence of increasing trend in summer PET anomalies, number of days above defined threshold, number of heat waves, and average duration of heat waves per year since 1981. Moreover, winter PET anomaly as well as the number of days below certain threshold and number of cold waves per year until 1980 was decreasing, but the decrease was not statistically significant. The highest number of heat waves during summer was registered in the last two decades, but also in the first decade of the investigated period. On the other hand, the number of cold waves during six decades is quite similar and the differences are very small.

  1. Quantification and assessment of heat and cold waves in Novi Sad, Northern Serbia

    NASA Astrophysics Data System (ADS)

    Basarin, Biljana; Lukić, Tin; Matzarakis, Andreas

    2016-01-01

    Physiologically equivalent temperature (PET) has been applied to the analysis of heat and cold waves and human thermal conditions in Novi Sad, Serbia. A series of daily minimum and maximum air temperature, relative humidity, wind, and cloud cover was used to calculate PET for the investigated period 1949-2012. The heat and cold wave analysis was carried out on days with PET values exceeding defined thresholds. Additionally, the acclimatization approach was introduced to evaluate human adaptation to interannual thermal perception. Trend analysis has revealed the presence of increasing trend in summer PET anomalies, number of days above defined threshold, number of heat waves, and average duration of heat waves per year since 1981. Moreover, winter PET anomaly as well as the number of days below certain threshold and number of cold waves per year until 1980 was decreasing, but the decrease was not statistically significant. The highest number of heat waves during summer was registered in the last two decades, but also in the first decade of the investigated period. On the other hand, the number of cold waves during six decades is quite similar and the differences are very small.

  2. Analysis of the 1980 heat wave in Memphis.

    PubMed

    Applegate, W B; Runyan, J W; Brasfield, L; Williams, M L; Konigsberg, C; Fouche, C

    1981-08-01

    During the heat wave of 1980, average daily temperatures in Memphis first rose above the mean on June 25 and remained elevated for 26 consecutive days. In July, 1980, 83 heat-related deaths were recorded as compared to non in July 1979. Most of these deaths occurred in elderly, poor, black, inner-city residents. There was a statistically significant increase in total mortality rates, death from natural causes, cardiovascular mortality rates, and the rate for persons dead on arrival. Virtually all the excess mortality was in persons over the age of 60. The rise in heat-related emergency room visits occurred three days prior to the rise in heat-related deaths. Local planning for future heat waves should focus on the inner-city black elderly. Heat-related deaths and emergency room visits should be reported to public health officials. PMID:7264123

  3. Stochastic threshold for ion heating with beating electrostatic waves.

    PubMed

    Jorns, B; Choueiri, E Y

    2013-06-14

    The stochastic threshold for the heating of ions in a magnetized plasma with two electrostatic waves is experimentally characterized. Two obliquely propagating electrostatic modes are launched in a magnetized plasma with frequencies that differ by the ion cyclotron frequency. The values of the wave amplitudes where a rapid increase in the local ion temperature occurs is then parametrically investigated. It is found that the two threshold wave amplitudes are linearly related and that this dependence translates to a lower required energy density for the onset of heating when compared to the case of a single electrostatic wave. Agreement also is demonstrated between the experimentally observed threshold for stochastic heating and an analytical prediction [B. Jorns and E. Y. Choueiri, Phys. Rev. E 87, 013107 (2013)] for this threshold. PMID:25165933

  4. An "H-index" for summer heat waves

    NASA Astrophysics Data System (ADS)

    Teuling, Ryan; Vautard, Robert

    2013-04-01

    Heat waves are among the most severely impacting natural disasters with which we contend. Recent summer "mega-heatwave" extremes in France (2003) and Russia (2010) lead to impacts on ecosystems and economic sectors, as well as increased mortality rates. Appropriate adaptation measures and improved early warning systems are necessary to cope with more frequent phenomena such as those that occurred in the last decade. A simple scale, that allows both identification, definition and ranking of individual heat wave events based on environmental conditions and potential for societal impact, is lacking. Such magnitude scale could also help to evaluate the evolution of heat waves in multi-model climate projections as compared to current climate. A simple index, easy to calculate and communicate, is designed to capture both the intensity and duration of summer heat waves. The index, analogous to the Hirsch index for citations, expresses the magnitude of a heat wave event (H) by the number of subsequent days H over which the daily average apparent temperature anomaly exceeds H K. It accounts for the magnitude of the day- and night-time temperature anomalies, humidity and wind, as well as for the duration of the heat wave episode. As a preliminary application, we calculated H over a 36 year-long global set of meteorological station data, after a careful quality check procedure. We show that these events, as characterised by H, have doubled in number over the past few decades. We also show that large magnitude heat waves (say H≥8) occur essentially in mid to high latitudes and over continental areas.

  5. Heat protection behaviors and positive affect about heat during the 2013 heat wave in the United Kingdom.

    PubMed

    Lefevre, Carmen E; Bruine de Bruin, Wändi; Taylor, Andrea L; Dessai, Suraje; Kovats, Sari; Fischhoff, Baruch

    2015-03-01

    Heat waves pose serious health risks, and are expected to become more frequent, longer lasting, and more intense in the future under a changing climate. Yet, people in the UK seem to feel positive when thinking about hot weather. According to research on the affect heuristic, any positive or negative emotions evoked by potentially risky experiences may be used as cues to inform concerns about risk protection. If so, then their positive feelings toward hot weather might lead UK residents to lower intentions to adopt heat protection behaviors. Here, we examine the relationships between heat protection behaviors during the July 2013 UK heat wave and self-reports of having heard heat protection recommendations, feeling positive affect about heat, seeing heat protection measures as effective, and trusting the organizations making those recommendations. Responses to a national survey revealed that 55.1% of participants had heard heat protection recommendations during the 2013 UK heat wave. Those who reported having heard recommendations also indicated having implemented more heat protection behaviors, perceiving heat protection behaviors as more effective, feeling more positive about heat, and intending to implement more protection behaviors in future hot summers. Mediation analyses suggested that heat protection recommendations may motivate heat protection behaviors by increasing their perceived effectiveness, but undermine their implementation by evoking positive affect about hot weather. We discuss our findings in the context of the affect heuristic and its implications for heat protection communications. PMID:25635375

  6. Heat Waves Pose Big Health Threats

    MedlinePlus

    ... in some locales, according to the U.S. National Weather Service. With these high temperatures come significant health ... Medicine, in Stratford, N.J. "Any extremes in weather can be inherently dangerous, but the initial heat ...

  7. Spectral Effects on Fast Wave Core Heating and Current Drive

    SciTech Connect

    C.K. Phillips, R.E. Bell, L.A. Berry, P.T. Bonoli, R.W. Harvey, J.C. Hosea, E.F. Jaeger, B.P. LeBlanc, P.M. Ryan, G. Taylor, E.J. Valeo, J.R. Wilson, J.C. Wright, H. Yuh, and the NSTX Team

    2009-05-11

    Recent results obtained with high harmonic fast wave (HHFW) heating and current drive (CD) on NSTX strongly support the hypothesis that the onset of perpendicular fast wave propagation right at or very near the launcher is a primary cause for a reduction in core heating efficiency at long wavelengths that is also observed in ICRF heating experiments in numerous tokamaks. A dramatic increase in core heating efficiency was first achieved in NSTX L-mode helium majority plasmas when the onset for perpendicular wave propagation was moved away from the antenna and nearby vessel structures. Efficient core heating in deuterium majority L mode and H mode discharges, in which the edge density is typically higher than in comparable helium majority plasmas, was then accomplished by reducing the edge density in front of the launcher with lithium conditioning and avoiding operational points prone to instabilities. These results indicate that careful tailoring of the edge density profiles in ITER should be considered to limit rf power losses to the antenna and plasma facing materials. Finally, in plasmas with reduced rf power losses in the edge regions, the first direct measurements of high harmonic fast wave current drive were obtained with the motional Stark effect (MSE) diagnostic. The location and radial dependence of HHFW CD measured by MSE are in reasonable agreement with predictions from both full wave and ray tracing simulations.

  8. Exploration of High Harmonic Fast Wave Heating on the National Spherical Torus Experiment

    SciTech Connect

    J.R. Wilson; R.E. Bell; S. Bernabei; M. Bitter; P. Bonoli; D. Gates; J. Hosea; B. LeBlanc; T.K. Mau; S. Medley; J. Menard; D. Mueller; M. Ono; C.K. Phillips; R.I. Pinsker; R. Raman; A. Rosenberg; P. Ryan; S. Sabbagh; D. Stutman; D. Swain; Y. Takase; J. Wilgen; the NSTX Team

    2003-02-11

    High Harmonic Fast Wave (HHFW) heating has been proposed as a particularly attractive means for plasma heating and current drive in the high-beta plasmas that are achievable in spherical torus (ST) devices. The National Spherical Torus Experiment (NSTX) [Ono, M., Kaye, S.M., Neumeyer, S., et al., Proceedings, 18th IEEE/NPSS Symposium on Fusion Engineering, Albuquerque, 1999, (IEEE, Piscataway, NJ (1999), p. 53.)] is such a device. An radio-frequency (rf) heating system has been installed on NSTX to explore the physics of HHFW heating, current drive via rf waves and for use as a tool to demonstrate the attractiveness of the ST concept as a fusion device. To date, experiments have demonstrated many of the theoretical predictions for HHFW. In particular, strong wave absorption on electrons over a wide range of plasma parameters and wave parallel phase velocities, wave acceleration of energetic ions, and indications of current drive for directed wave spectra have been observed. In addition HHFW heating has been used to explore the energy transport properties of NSTX plasmas, to create H-mode (high-confinement mode) discharges with a large fraction of bootstrap current and to control the plasma current profile during the early stages of the discharge.

  9. In-depth Plasma-Wave Heating of Dense Plasma Irradiated by Short Laser Pulses

    NASA Astrophysics Data System (ADS)

    Sherlock, M.; Hill, E. G.; Evans, R. G.; Rose, S. J.; Rozmus, W.

    2014-12-01

    We investigate the mechanism by which relativistic electron bunches created at the surface of a target irradiated by a very short and intense laser pulse transfer energy to the deeper parts of the target. In existing theories, the dominant heating mechanism is that of resistive heating by the neutralizing return current. In addition to this, we find that large amplitude plasma waves are induced in the plasma in the wake of relativistic electron bunches. The subsequent collisional damping of these waves represents a source of heating that can exceed the resistive heating rate. As a result, solid targets heat significantly faster than has been previously considered. A new hybrid model, capable of reproducing these results, is described.

  10. On the physics of waves in the solar atmosphere: Wave heating and wind acceleration

    NASA Technical Reports Server (NTRS)

    Musielak, Z. E.

    1992-01-01

    In the area of solar physics, new calculations of the acoustic wave energy fluxes generated in the solar convective zone was performed. The original theory developed was corrected by including a new frequency factor describing temporal variations of the turbulent energy spectrum. We have modified the original Stein code by including this new frequency factor, and tested the code extensively. Another possible source of the mechanical energy generated in the solar convective zone is the excitation of magnetic flux tube waves which can carry energy along the tubes far away from the region. The problem as to how efficiently those waves are generated in the Sun was recently solved. The propagation of nonlinear magnetic tube waves in the solar atmosphere was calculated, and mode coupling, shock formation, and heating of the local medium was studied. The wave trapping problems and evaluation of critical frequencies for wave reflection in the solar atmosphere was studied. It was shown that the role played by Alfven waves in the wind accelerations and the coronal hole heating is dominant. Presently, we are performing calculations of wave energy fluxes generated in late-type dwarf stars and studying physical processes responsible for the heating of stellar chromospheres and coronae. In the area of physics of waves, a new analytical approach for studying linear Alfven waves in smoothly nonuniform media was recently developed. This approach is presently being extended to study the propagation of linear and nonlinear magnetohydrodynamic (MHD) waves in stratified, nonisothermal and solar atmosphere. The Lighthill theory of sound generation to nonisothermal media (with a special temperature distribution) was extended. Energy cascade by nonlinear MHD waves and possible chaos driven by these waves are presently considered.

  11. Spectral effects on fast wave core heating and current drive

    NASA Astrophysics Data System (ADS)

    Phillips, C. K.; Bell, R. E.; Berry, L. A.; Bonoli, P. T.; Harvey, R. W.; Hosea, J. C.; Jaeger, E. F.; LeBlanc, B. P.; Ryan, P. M.; Taylor, G.; Valeo, E. J.; Wilgen, J. B.; Wilson, J. R.; Wright, J. C.; Yuh, H.; NSTX Team

    2009-07-01

    Recent results obtained with high harmonic fast wave (HHFW) heating and current drive (CD) on NSTX strongly support the hypothesis that the onset of perpendicular fast wave propagation right at or very near the launcher is a primary cause for a reduction in core heating efficiency at long wavelengths that is also observed in ICRF heating experiments in numerous tokamaks. A dramatic increase in core heating efficiency was first achieved in NSTX L-mode helium majority plasmas when the onset for perpendicular wave propagation was moved away from the antenna and nearby vessel structures. Efficient core heating in deuterium majority L-mode and H-mode discharges, in which the edge density is typically higher than in comparable helium majority plasmas, was then accomplished by reducing the edge density in front of the launcher with lithium conditioning and avoiding operational points prone to instabilities. These results indicate that careful tailoring of the edge density profiles in ITER should be considered to limit radio frequency (rf) power losses to the antenna and plasma facing materials. Finally, in plasmas with reduced rf power losses in the edge regions, the first direct measurements of HHFW CD were obtained with the motional Stark effect (MSE) diagnostic. The location and radial dependence of HHFW CD measured by MSE are in reasonable agreement with predictions from both full wave and ray tracing simulations.

  12. Heat-wave-related mortality--Milwaukee, Wisconsin, July 1995.

    PubMed

    1996-06-21

    During July 12-15, 1995, a heat wave occurred in major portions of the midwestern and eastern United States. Record-high temperatures were recorded at approximately 70 locations, ranging from the central and northern Great Plains to the Atlantic coast and caused substantial numbers of heat-related illnesses and deaths in some locations. In Milwaukee, Wisconsin (1994 estimated population: 938,112), maximum daily temperatures ranged from 91 F (32.7 C) to 103 F (39.5 C), and average daily humidity was as high as 70%. This report summarizes the investigation by the Milwaukee County Medical Examiner's Office (MCMEO) and the Milwaukee Department of Health and Social Services of heat-related deaths in Milwaukee during the heat wave and presents four case reports. PMID:9132565

  13. A hot topic--heat waves and stroke.

    PubMed

    Chan, Fiona; Francis, Oliver; Dodd, Lizzie; Mahdi, Zain; Koblar, Simon A

    2014-10-01

    Following a heat wave in January 2014 in Adelaide, state capital of South Australia, we asked the question whether extreme heat was associated with an increase in stroke incidence. We found in the literature that the association between stroke presentation to hospital and meteorological factors has long been a topic of debate and subject to numerous studies. The literature indicated that an association between heat waves and an increase in admissions for stroke was unlikely in Australia and the United States. We suggest that it may be inappropriate to generalize this conclusion to other countries and rural areas. In view of the global climate change debate, we suggest that prospective studies be focused in developing countries and rural areas to assess the real impact of extreme heat on respective populations to better inform stroke physicians and health policy makers.

  14. A hot topic--heat waves and stroke.

    PubMed

    Chan, Fiona; Francis, Oliver; Dodd, Lizzie; Mahdi, Zain; Koblar, Simon A

    2014-10-01

    Following a heat wave in January 2014 in Adelaide, state capital of South Australia, we asked the question whether extreme heat was associated with an increase in stroke incidence. We found in the literature that the association between stroke presentation to hospital and meteorological factors has long been a topic of debate and subject to numerous studies. The literature indicated that an association between heat waves and an increase in admissions for stroke was unlikely in Australia and the United States. We suggest that it may be inappropriate to generalize this conclusion to other countries and rural areas. In view of the global climate change debate, we suggest that prospective studies be focused in developing countries and rural areas to assess the real impact of extreme heat on respective populations to better inform stroke physicians and health policy makers. PMID:25231580

  15. Should electric fans be used during a heat wave?

    PubMed

    Jay, Ollie; Cramer, Matthew N; Ravanelli, Nicholas M; Hodder, Simon G

    2015-01-01

    Heat waves continue to claim lives, with the elderly and poor at greatest risk. A simple and cost-effective intervention is an electric fan, but public health agencies warn against their use despite no evidence refuting their efficacy in heat waves. A conceptual human heat balance model can be used to estimate the evaporative requirement for heat balance, the potential for evaporative heat loss from the skin, and the predicted sweat rate, with and without an electrical fan during heat wave conditions. Using criteria defined by the literature, it is clear that fans increase the predicted critical environmental limits for both the physiological compensation of endogenous/exogenous heat, and the onset of cardiovascular strain by an air temperature of ∼3-4 °C, irrespective of relative humidity (RH) for the young and elderly. Even above these critical limits, fans would apparently still provide marginal benefits at air temperatures as high as 51.1 °C at 10%RH for young adults and 48.1 °C at 10%RH for the elderly. Previous concerns that dehydration would be exacerbated with fan use do not seem likely, except under very hot (>40 °C) and dry (<10%RH) conditions, when predicted sweat losses are only greater with fans by a minor amount (∼20-30 mL/h). Relative to the peak outdoor environmental conditions reported during ten of the most severe heat waves in recent history, fan use would be advisable in all of these situations, even when reducing the predicted maximum sweat output for the elderly. The protective benefit of fans appears to be underestimated by current guidelines.

  16. Should electric fans be used during a heat wave?

    PubMed

    Jay, Ollie; Cramer, Matthew N; Ravanelli, Nicholas M; Hodder, Simon G

    2015-01-01

    Heat waves continue to claim lives, with the elderly and poor at greatest risk. A simple and cost-effective intervention is an electric fan, but public health agencies warn against their use despite no evidence refuting their efficacy in heat waves. A conceptual human heat balance model can be used to estimate the evaporative requirement for heat balance, the potential for evaporative heat loss from the skin, and the predicted sweat rate, with and without an electrical fan during heat wave conditions. Using criteria defined by the literature, it is clear that fans increase the predicted critical environmental limits for both the physiological compensation of endogenous/exogenous heat, and the onset of cardiovascular strain by an air temperature of ∼3-4 °C, irrespective of relative humidity (RH) for the young and elderly. Even above these critical limits, fans would apparently still provide marginal benefits at air temperatures as high as 51.1 °C at 10%RH for young adults and 48.1 °C at 10%RH for the elderly. Previous concerns that dehydration would be exacerbated with fan use do not seem likely, except under very hot (>40 °C) and dry (<10%RH) conditions, when predicted sweat losses are only greater with fans by a minor amount (∼20-30 mL/h). Relative to the peak outdoor environmental conditions reported during ten of the most severe heat waves in recent history, fan use would be advisable in all of these situations, even when reducing the predicted maximum sweat output for the elderly. The protective benefit of fans appears to be underestimated by current guidelines. PMID:25134988

  17. Combatting the heat wave of 1980: lessons for the future.

    PubMed

    Allexenberg, R S

    1981-09-01

    Throughout the summer of 1980, much of the nation suffered record-breaking, sustained hot and often humid weather. In cities throughout the country, the oppressive heat often led to crisis situations, and emergency procedures were hastily developed to provide shelter and medical assistance. The heat wave of 1980 was particularly severe in St. Louis, Missouri. On July 17, hospital visits and admissions related to the heat reached a peak of 54 cases. Death rates soared. During the period from June 21 to July 28, the number of deaths in St. Louis rose by 40.6 percent--from 864 deaths in 1979 to 1,215 in the same period in 1980--with the heaviest toll among the poor and elderly. Heat waves of significant medical and social implications are not new to St. Louis. Indeed, conditions similar to 1980 have occurred ten times since 1911, with the most recent heat wave prior to 1980 occurring in 1966. The long periods between crises have caused medical and social planners to neglect or overlook preparations for heat-related illness. Consequently, each new government and medical generation has to deal with these crises from "scratch." PMID:10253341

  18. The urban heat island dynamics during heat waves: a study of cities in the United States

    NASA Astrophysics Data System (ADS)

    Hu, Leiqiu

    2016-04-01

    The urban heat island (UHI) is a common phenomenon describing that metropolitan areas are usually warmer than their rural surroundings. This effect is compounded by extreme heat events, which are a leading cause of weather-related human mortality in many countries worldwide. However, the spatial and diurnal variability of temperature and humidity in urban and adjacent rural areas during extreme heat events is not well measured and therefore not well understood. The recently developed dataset of near-surface air and dew temperature from MODIS atmospheric profiles and the new method for the UHI quantification--urban heat island curve are used to quantify the urban climatic changes during heat waves in cities of the United States. The enhanced and weakened UHIs are observed in various cities. The causes of UHI changes during heat waves are discussed, including climate region, vegetation type and amount, city geolocation, etc.

  19. Preliminary Results from Numerical Experiments on the Summer 1980 Heat Wave and Drought

    NASA Technical Reports Server (NTRS)

    Wolfson, N.; Atlas, R.; Sud, Y. C.

    1985-01-01

    During the summer of 1980, a prolonged heat wave and drought affected the United States. A preliminary set of experiments has been conducted to study the effect of varying boundary conditions on the GLA model simulation of the heat wave. Five 10-day numerical integrations with three different specifications of boundary conditions were carried out: a control experiment which utilized climatological boundary conditions, an SST experiment which utilized summer 1980 sea-surface temperatures in the North Pacific, but climatological values elsewhere, and a Soil Moisture experiment which utilized the values of Mintz-Serafini for the summer, 1980. The starting dates for the five forecasts were 11 June, 7 July, 21 July, 22 August, and 6 September of 1980. These dates were specifically chosen as days when a heat wave was already established in order to investigate the effect of soil moistures or North Pacific sea-surface temperatures on the model's ability to maintain the heat wave pattern. The experiments were evaluated in terms of the heat wave index for the South Plains, North Plains, Great Plains and the entire U.S. In addition a subjective comparison of map patterns has been performed.

  20. Solar Jets as Sources of Outflows, Heating and Waves

    NASA Astrophysics Data System (ADS)

    Nishizuka, N.

    2013-05-01

    Recent space solar observations of the Sun, such as Hinode and SDO, have revealed that magnetic reconnection is ubiquitous in the solar atmosphere, ranging from small scale reconnection (observed as nanoflares) to large scale one (observed as long duration flares or giant arcades). Especially recent Hinode observations has found various types of tiny chromospheric jets, such as chromospheric anemone jets, penumbral microjets and light bridge jets from sunspot umbra. It was also found that the corona is full of tiny X-ray jets. Often they are seen as helical spinning jets with Alfvenic waves in the corona. Sometimes they are seen as chromospheric jets with slow-mode magnetoacoustic waves and sometimes as unresolved jet-like events at the footpoint of recurrent outflows and waves at the edge of the active region. There is increasing evidence of magnetic reconnection in these tiny jets and its association with waves. The origin of outflows and waves is one of the issues concerning coronal heating and solar wind acceleration. To answer this question, we had a challenge to reproduce solar jets with laboratory plasma experiment and directly measured outflows and waves. As a result, we could find a propagating wave excited by magnetic reconnection, whose energy flux is 10% of the released magnetic energy. That is enough for solar wind acceleration and locally enough for coronal heating, consistent with numerical MHD simulations of solar jets. Here we would discuss recent observations with Hinode, theories and experimental results related to jets and waves by magnetic reconnection, and discuss possible implication to reconnection physics, coronal heating and solar wind acceleration.

  1. The 2011 heat wave in Greater Houston: Effects of land use on temperature.

    PubMed

    Zhou, Weihe; Ji, Shuang; Chen, Tsun-Hsuan; Hou, Yi; Zhang, Kai

    2014-11-01

    Effects of land use on temperatures during severe heat waves have been rarely studied. This paper examines land use-temperature associations during the 2011 heat wave in Greater Houston. We obtained high resolution of satellite-derived land use data from the US National Land Cover Database, and temperature observations at 138 weather stations from Weather Underground, Inc (WU) during the August of 2011, which was the hottest month in Houston since 1889. Land use regression and quantile regression methods were applied to the monthly averages of daily maximum/mean/minimum temperatures and 114 land use-related predictors. Although selected variables vary with temperature metric, distance to the coastline consistently appears among all models. Other variables are generally related to high developed intensity, open water or wetlands. In addition, our quantile regression analysis shows that distance to the coastline and high developed intensity areas have larger impacts on daily average temperatures at higher quantiles, and open water area has greater impacts on daily minimum temperatures at lower quantiles. By utilizing both land use regression and quantile regression on a recent heat wave in one of the largest US metropolitan areas, this paper provides a new perspective on the impacts of land use on temperatures. Our models can provide estimates of heat exposures for epidemiological studies, and our findings can be combined with demographic variables, air conditioning and relevant diseases information to identify 'hot spots' of population vulnerability for public health interventions to reduce heat-related health effects during heat waves.

  2. The 2011 marine heat wave in Cockburn Sound, southwest Australia

    NASA Astrophysics Data System (ADS)

    Rose, T. H.; Smale, D. A.; Botting, G.

    2012-07-01

    Over 2000 km of Western Australian coastline experienced a significant marine heat wave in February and March 2011. Seawater temperature anomalies of +2-4 °C were recorded at a number of locations, and satellite-derived SSTs (sea surface temperatures) were the highest on record. Here, we present seawater temperatures from southwestern Australia and describe, in detail, the marine climatology of Cockburn Sound, a large, multiple-use coastal embayment. We compared temperature and dissolved oxygen levels in 2011 with data from routine monitoring conducted from 2002-2010. A significant warming event, 2-4 °C in magnitude, persisted for > 8 weeks, and seawater temperatures at 10 to 20 m depth were significantly higher than those recorded in the previous 9 yr. Dissolved oxygen levels were depressed at most monitoring sites, being ~ 2 mg l-1 lower than usual in early March 2011. Ecological responses to short-term extreme events are poorly understood, but evidence from elsewhere along the Western Australian coastline suggests that the heat wave was associated with high rates of coral bleaching; fish, invertebrate and macroalgae mortalities; and algal blooms. However, there is a paucity of historical information on ecologically-sensitive habitats and taxa in Cockburn Sound, so that formal examinations of biological responses to the heat wave were not possible. The 2011 heat wave provided insights into conditions that may become more prevalent in Cockburn Sound, and elsewhere, if the intensity and frequency of short-term extreme events increases as predicted.

  3. Temperature and heat wave trends in northwest Mexico

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

  4. Heat Waves, Droughts, and Preferences for Environmental Policy

    ERIC Educational Resources Information Center

    Owen, Ann L.; Conover, Emily; Videras, Julio; Wu, Stephen

    2012-01-01

    Using data from a new household survey on environmental attitudes, behaviors, and policy preferences, we find that current weather conditions affect preferences for environmental regulation. Individuals who have recently experienced extreme weather (heat waves or droughts) are more likely to support laws to protect the environment. We find…

  5. Behavior of a Moist Kelvin Wave Packet with Nonlinear Heating.

    NASA Astrophysics Data System (ADS)

    Wang, Bin; Xue, Yan

    1992-04-01

    The effects of nonlinear (positive only or conditional) heating on moist Kelvin waves are examined with a simple equatorial zonal-plane model describing the gravest baroclinic mode.The unstable perturbation subject to nonlinear beating emerges as a wave packet. A typical amplifying, eastward-moving wave packet is characterized by an asymmetric structure: 1) the ascending branch (wet region) is much narrower than the two descending ones (dry regions); and 2) the circulation cell to the east of the wet region center is smaller and stronger than its counterpart to the west of the center. The wet-dry asymmetry is primarily caused by the nonlinear beating effect, while the east-west asymmetry is a result of the movement of the wave packet relative to mean flow. The existence of Newtonian cooling and Rayleigh friction enhances the structural asymmetries.The unstable wave packet is characterized by two zonal length scales: the ascending branch length (ABL) and total circulation extent (TCE). For a given basic state, the growth rate of a wave packet increases with decreasing ABL or TCE. However, up to a moderate growth rate (order of day1) the energy spectra of all wave packets are dominated by zonal wavenumber one regardless of ABL size. In particular, the slowly growing (low frequency) wave packets normally exhibit TCEs of planetary scale and ABLs of synoptic scale.Observed equatorial intraseasonal disturbances often display a narrow convection region in between two much broader dry regions and a total circulation of planetary scale. These structure and scale characteristics are caused by the effects of nonlinear heating and the cyclic geometry of the equator. It is argued that the unstable disturbance found in numerical experiments (e.g., Lau and Peng; Hayashi and Sumi) is a manifestation of the nonlinear wave packet.

  6. Responses of tree species to heat waves and extreme heat events.

    PubMed

    Teskey, Robert; Wertin, Timothy; Bauweraerts, Ingvar; Ameye, Maarten; McGuire, Mary Anne; Steppe, Kathy

    2015-09-01

    The number and intensity of heat waves has increased, and this trend is likely to continue throughout the 21st century. Often, heat waves are accompanied by drought conditions. It is projected that the global land area experiencing heat waves will double by 2020, and quadruple by 2040. Extreme heat events can impact a wide variety of tree functions. At the leaf level, photosynthesis is reduced, photooxidative stress increases, leaves abscise and the growth rate of remaining leaves decreases. In some species, stomatal conductance increases at high temperatures, which may be a mechanism for leaf cooling. At the whole plant level, heat stress can decrease growth and shift biomass allocation. When drought stress accompanies heat waves, the negative effects of heat stress are exacerbated and can lead to tree mortality. However, some species exhibit remarkable tolerance to thermal stress. Responses include changes that minimize stress on photosynthesis and reductions in dark respiration. Although there have been few studies to date, there is evidence of within-species genetic variation in thermal tolerance, which could be important to exploit in production forestry systems. Understanding the mechanisms of differing tree responses to extreme temperature events may be critically important for understanding how tree species will be affected by climate change.

  7. The impact of heat waves on children's health: a systematic review.

    PubMed

    Xu, Zhiwei; Sheffield, Perry E; Su, Hong; Wang, Xiaoyu; Bi, Yan; Tong, Shilu

    2014-03-01

    Young children are thought to be particularly sensitive to heat waves, but relatively less research attention has been paid to this field to date. A systematic review was conducted to elucidate the relationship between heat waves and children's health. Literature published up to August 2012 were identified using the following MeSH terms and keywords: "heatwave", "heat wave", "child health", "morbidity", "hospital admission", "emergency department visit", "family practice", "primary health care", "death" and "mortality". Of the 628 publications identified, 12 met the selection criteria. The existing literature does not consistently suggest that mortality among children increases significantly during heat waves, even though infants were associated with more heat-related deaths. Exposure to heat waves in the perinatal period may pose a threat to children's health. Pediatric diseases or conditions associated with heat waves include renal disease, respiratory disease, electrolyte imbalance and fever. Future research should focus on how to develop a consistent definition of a heat wave from a children's health perspective, identifying the best measure of children's exposure to heat waves, exploring sensitive outcome measures to quantify the impact of heat waves on children, evaluating the possible impacts of heat waves on children's birth outcomes, and understanding the differences in vulnerability to heat waves among children of different ages and from different income countries. Projection of the children's disease burden caused by heat waves under climate change scenarios, and development of effective heat wave mitigation and adaptation strategies that incorporate other child protective health measures, are also strongly recommended.

  8. The impact of heat waves on children's health: a systematic review

    NASA Astrophysics Data System (ADS)

    Xu, Zhiwei; Sheffield, Perry E.; Su, Hong; Wang, Xiaoyu; Bi, Yan; Tong, Shilu

    2014-03-01

    Young children are thought to be particularly sensitive to heat waves, but relatively less research attention has been paid to this field to date. A systematic review was conducted to elucidate the relationship between heat waves and children's health. Literature published up to August 2012 were identified using the following MeSH terms and keywords: "heatwave", "heat wave", "child health", "morbidity", "hospital admission", "emergency department visit", "family practice", "primary health care", "death" and "mortality". Of the 628 publications identified, 12 met the selection criteria. The existing literature does not consistently suggest that mortality among children increases significantly during heat waves, even though infants were associated with more heat-related deaths. Exposure to heat waves in the perinatal period may pose a threat to children's health. Pediatric diseases or conditions associated with heat waves include renal disease, respiratory disease, electrolyte imbalance and fever. Future research should focus on how to develop a consistent definition of a heat wave from a children's health perspective, identifying the best measure of children's exposure to heat waves, exploring sensitive outcome measures to quantify the impact of heat waves on children, evaluating the possible impacts of heat waves on children's birth outcomes, and understanding the differences in vulnerability to heat waves among children of different ages and from different income countries. Projection of the children's disease burden caused by heat waves under climate change scenarios, and development of effective heat wave mitigation and adaptation strategies that incorporate other child protective health measures, are also strongly recommended.

  9. Probability of US Heat Waves Affected by a Subseasonal Planetary Wave Pattern

    NASA Technical Reports Server (NTRS)

    Teng, Haiyan; Branstator, Grant; Wang, Hailan; Meehl, Gerald A.; Washington, Warren M.

    2013-01-01

    Heat waves are thought to result from subseasonal atmospheric variability. Atmospheric phenomena driven by tropical convection, such as the Asian monsoon, have been considered potential sources of predictability on subseasonal timescales. Mid-latitude atmospheric dynamics have been considered too chaotic to allow significant prediction skill of lead times beyond the typical 10-day range of weather forecasts. Here we use a 12,000-year integration of an atmospheric general circulation model to identify a pattern of subseasonal atmospheric variability that can help improve forecast skill for heat waves in the United States. We find that heat waves tend to be preceded by 15-20 days by a pattern of anomalous atmospheric planetary waves with a wavenumber of 5. This circulation pattern can arise as a result of internal atmospheric dynamics and is not necessarily linked to tropical heating.We conclude that some mid-latitude circulation anomalies that increase the probability of heat waves are predictable beyond the typical weather forecast range.

  10. Circulating heat exchangers for oscillating wave engines and refrigerators

    DOEpatents

    Swift, Gregory W.; Backhaus, Scott N.

    2003-10-28

    An oscillating-wave engine or refrigerator having a regenerator or a stack in which oscillating flow of a working gas occurs in a direction defined by an axis of a trunk of the engine or refrigerator, incorporates an improved heat exchanger. First and second connections branch from the trunk at locations along the axis in selected proximity to one end of the regenerator or stack, where the trunk extends in two directions from the locations of the connections. A circulating heat exchanger loop is connected to the first and second connections. At least one fluidic diode within the circulating heat exchanger loop produces a superimposed steady flow component and oscillating flow component of the working gas within the circulating heat exchanger loop. A local process fluid is in thermal contact with an outside portion of the circulating heat exchanger loop.

  11. Bulk ion heating with ICRF waves in tokamaks

    NASA Astrophysics Data System (ADS)

    Mantsinen, M. J.; Bilato, R.; Bobkov, V. V.; Kappatou, A.; McDermott, R. M.; Nocente, M.; Odstrčil, T.; Tardini, G.; Bernert, M.; Dux, R.; Hellsten, T.; Mantica, P.; Maraschek, M.; Nielsen, S. K.; Noterdaeme, J.-M.; Rasmussen, J.; Ryter, F.; Stejner, M.; Stober, J.; Tardocchi, M.

    2015-12-01

    Heating with ICRF waves is a well-established method on present-day tokamaks and one of the heating systems foreseen for ITER. However, further work is still needed to test and optimize its performance in fusion devices with metallic high-Z plasma facing components (PFCs) in preparation of ITER and DEMO operation. This is of particular importance for the bulk ion heating capabilities of ICRF waves. Efficient bulk ion heating with the standard ITER ICRF scheme, i.e. the second harmonic heating of tritium with or without 3He minority, was demonstrated in experiments carried out in deuterium-tritium plasmas on JET and TFTR and is confirmed by ICRF modelling. This paper focuses on recent experiments with 3He minority heating for bulk ion heating on the ASDEX Upgrade (AUG) tokamak with ITER-relevant all-tungsten PFCs. An increase of 80% in the central ion temperature Ti from 3 to 5.5 keV was achieved when 3 MW of ICRF power tuned to the central 3He ion cyclotron resonance was added to 4.5 MW of deuterium NBI. The radial gradient of the Ti profile reached locally values up to about 50 keV/m and the normalized logarithmic ion temperature gradients R/LTi of about 20, which are unusually large for AUG plasmas. The large changes in the Ti profiles were accompanied by significant changes in measured plasma toroidal rotation, plasma impurity profiles and MHD activity, which indicate concomitant changes in plasma properties with the application of ICRF waves. When the 3He concentration was increased above the optimum range for bulk ion heating, a weaker peaking of the ion temperature profile was observed, in line with theoretical expectations.

  12. Bulk ion heating with ICRF waves in tokamaks

    SciTech Connect

    Mantsinen, M. J.; Bilato, R.; Bobkov, V. V.; Kappatou, A.; McDermott, R. M.; Odstrčil, T.; Tardini, G.; Bernert, M.; Dux, R.; Maraschek, M.; Noterdaeme, J.-M.; Ryter, F.; Stober, J.; Nocente, M.; Hellsten, T.; Mantica, P.; Tardocchi, M.; Nielsen, S. K.; Rasmussen, J.; Stejner, M.; and others

    2015-12-10

    Heating with ICRF waves is a well-established method on present-day tokamaks and one of the heating systems foreseen for ITER. However, further work is still needed to test and optimize its performance in fusion devices with metallic high-Z plasma facing components (PFCs) in preparation of ITER and DEMO operation. This is of particular importance for the bulk ion heating capabilities of ICRF waves. Efficient bulk ion heating with the standard ITER ICRF scheme, i.e. the second harmonic heating of tritium with or without {sup 3}He minority, was demonstrated in experiments carried out in deuterium-tritium plasmas on JET and TFTR and is confirmed by ICRF modelling. This paper focuses on recent experiments with {sup 3}He minority heating for bulk ion heating on the ASDEX Upgrade (AUG) tokamak with ITER-relevant all-tungsten PFCs. An increase of 80% in the central ion temperature T{sub i} from 3 to 5.5 keV was achieved when 3 MW of ICRF power tuned to the central {sup 3}He ion cyclotron resonance was added to 4.5 MW of deuterium NBI. The radial gradient of the T{sub i} profile reached locally values up to about 50 keV/m and the normalized logarithmic ion temperature gradients R/LT{sub i} of about 20, which are unusually large for AUG plasmas. The large changes in the T{sub i} profiles were accompanied by significant changes in measured plasma toroidal rotation, plasma impurity profiles and MHD activity, which indicate concomitant changes in plasma properties with the application of ICRF waves. When the {sup 3}He concentration was increased above the optimum range for bulk ion heating, a weaker peaking of the ion temperature profile was observed, in line with theoretical expectations.

  13. Do Heat Waves have an Impact on Terrestrial Water Storage?

    NASA Astrophysics Data System (ADS)

    Brena-Naranjo, A.; Teuling, R.; Pedrozo-Acuña, A.

    2014-12-01

    Recent works have investigated the impact of heat waves on the surface energy and carbon balance. However, less attention has been given to the impacts on terrestrial hydrology. During the summer of 2010, the occurrence of an exceptional heat wave affected severely the Northern Hemisphere. The extension (more than 2 million km2) and severity of this extreme event caused substantial ecosystem damage (more than 1 million ha of forest fires), economic and human losses (~500 billion USD and more than 17 million of indirect deaths, respectively). This work investigates for the first time the impacts of the 2010 summer heat wave on terrestrial water storage. Our study area comprises three different regions where air temperature records were established or almost established during the summer: Western Russia, the Middle East and Eastern Sahel. Anomalies of terrestrial water storage derived from the Gravity Recovery and Climate Experiment (GRACE) were used to infer water storage deficits during the 2003-2013 period. Our analysis shows that Russia experienced the most severe water storage decline, followed by the Middle East, whereas Eastern Sahel was not significantly affected. The impact of the heat wave was spatially uniform in Russia but highly variable in the Middle East, with the Northern part substantially more affected than the Southern region. Lag times between maxima air temperatures and lower water storage deficits for Russia and the Middle East were approximately two and seven months, respectively. The results suggest that the response of terrestrial water storage to heat waves is stronger in energy-limited environments than in water-limited regions. Such differences in the magnitude and timing between meteorological and hydrological extremes can be explained by the propagation time between atmospheric water demand and natural or anthropogenic sources of water storage.

  14. Two-Dimensional, Supersonic, Linearized Flow with Heat Addition

    NASA Technical Reports Server (NTRS)

    Lomax, Harvard

    1959-01-01

    Calculations are presented for the forces on a thin supersonic wing underneath which the air is heated. The analysis is limited principally to linearized theory but nonlinear effects are considered. It is shown that significant advantages to external heating would exist if the heat were added well below and ahead of the wing.

  15. Closed Field Coronal Heating Models Inspired by Wave Turbulence

    NASA Astrophysics Data System (ADS)

    Downs, C.; Lionello, R.; Mikic, Z.; Linker, J.; Velli, M. M.

    2013-12-01

    To simulate the energy balance of coronal plasmas on macroscopic scales, we often require the specification of the coronal heating mechanism in some functional form. To go beyond empirical formulations and to build a more physically motivated heating function, we investigate the wave-turbulence dissipation (WTD) phenomenology for the heating of closed coronal loops. To do so, we employ an implementation of non-WKB equations designed to capture the large-scale propagation, reflection, and dissipation of wave turbulence along a loop. The parameter space of this model is explored by solving the coupled WTD and hydrodynamic equations in 1D for an idealized loop, and the relevance to a range of solar conditions is established by computing solutions for several hundred loops extracted from a realistic 3D coronal field. Due to the implicit dependence of the WTD heating model on loop geometry and plasma properties along the loop and at the footpoints, we find that this model can significantly reduce the number of free parameters when compared to traditional empirical heating models, and still robustly describe a broad range of quiet-sun and active region conditions. The importance of the self-reflection term in producing realistic heating scale heights and thermal non-equilibrium cycles is discussed, and preliminary 3D thermodynamic MHD simulations using this formulation are presented. Research supported by NASA and NSF.

  16. Eddy heat fluxes and stability of planetary waves. I, II

    NASA Technical Reports Server (NTRS)

    Lin, C. A.

    1980-01-01

    The stability of baroclinic Rossby waves in a zonal shear flow was analyzed by a linear, quasigeostrophic, two-level, adiabatic, and frictionless midlatitude beta-plane model. The ratio of the basic wave scale and the radius of deformation together with two nondimensional parameters which describe the amplitudes of the barotropic and baroclinic components of the basic wave constitute the three parameters of the stability problem. The parameter space is partitioned according to the dominant energy source for instability; the Lorenz and Kim conditions are characterized by significant horizontal and vertical shears of the basic wave, while the Phillips regime has a strong zonal flow. The stability analysis is then applied to the atmosphere, with the primary motivation being to examine the midlatitude planetary scale (zonal wavenumbers 1, 2, 3) transient waves that transport heat. It is found that the most unstable mode consists of a spectrum of waves, with a maximum amplitude at wavenumber 3; the response is thus maximum at a zonal scale intermediate between the basic wave scale and the radius of deformation.

  17. Evidence for wave heating of the quiet-sun corona

    SciTech Connect

    Hahn, M.; Savin, D. W.

    2014-11-10

    We have measured the energy and dissipation of Alfvénic waves in the quiet Sun. A magnetic field model was used to infer the location and orientation of the magnetic field lines along which the waves are expected to travel. The waves were measured using spectral lines to infer the wave amplitude. The waves cause a non-thermal broadening of the spectral lines, which can be expressed as a non-thermal velocity v {sub nt}. By combining the spectroscopic measurements with this magnetic field model, we were able to trace the variation of v {sub nt} along the magnetic field. At each footpoint of the quiet-Sun loops, we find that waves inject an energy flux in the range of 1.3-5.5 × 10{sup 5} erg cm{sup –2} s{sup –1}. At the minimum of this range, this amounts to more than 80% of the energy needed to heat the quiet Sun. We also find that these waves are dissipated over a region centered on the top of the loops. The position along the loop where the damping begins is strongly correlated with the length of the loop, implying that the damping mechanism depends on the global loop properties rather than on local collisional dissipation.

  18. Seasonal analysis of cold and heat waves in Serbia during the period 1949-2012

    NASA Astrophysics Data System (ADS)

    Unkašević, Miroslava; Tošić, Ivana

    2015-04-01

    Climate change has become one of the subjects most analysed by researchers, mainly because of the numerous extreme events that have hit the globe. A series of daily minimum and maximum temperatures at 15 stations in Serbia were used to calculate temperature indices, from which the duration and severity of cold and heat waves were estimated. Seasonal analysis was based on data from 1949 to 2012. The year 2012 saw severe cooling in Serbia, the longest heat waves during the summer and the worst drought since observations began — three major climate anomalies all in 1 year. An analysis of the daily minimum temperatures at almost all meteorological stations during the winter season revealed that the longest cold waves were observed in 1956. The longest heat waves were observed during the summer of 2012 in Serbia at ten out of 15 stations, but they did not reach the severity of those in July 2007. In addition, the main characteristics of the circulation conditions which caused the longest cold and heat waves in Serbia were analysed.

  19. Collisionless inter-species energy transfer and turbulent heating in drift wave turbulence

    SciTech Connect

    Zhao, L.; Diamond, P. H.

    2012-08-15

    We reconsider the classic problems of calculating 'turbulent heating' and collisionless inter-species transfer of energy in drift wave turbulence. These issues are of interest for low collisionality, electron heated plasmas, such as ITER, where collisionless energy transfer from electrons to ions is likely to be significant. From the wave Poynting theorem at steady state, a volume integral over an annulus r{sub 1}heating as {integral}{sub r{sub 1}} {sup r{sub 2}} dr=-S{sub r}|{sub r{sub 1}{sup r{sub 2}}}{ne}0. Here S{sub r} is the wave energy density flux in the radial direction. Thus, a wave energy flux differential across an annular region indeed gives rise to a net heating, in contrast to previous predictions. This heating is related to the Reynolds work by the zonal flow, since S{sub r} is directly linked to the zonal flow drive. In addition to net heating, there is inter-species heat transfer. For collisionless electron drift waves, the total turbulent energy source for collisionless heat transfer is due to quasilinear electron cooling. Subsequent quasilinear ion heating occurs through linear ion Landau damping. In addition, perpendicular heating via ion polarization currents contributes to ion heating. Since at steady state, Reynolds work of the turbulence on the zonal flow must balance zonal flow frictional damping ({approx}{nu}{sub ii}{sup 2}{approx}|(e{phi}(tilde sign)/T)|{sup 4}), it is no surprise that zonal flow friction appears as an important channel for ion heating. This process of energy transfer via zonal flow has not previously been accounted for in analyses of energy transfer. As an application, we compare the rate of turbulent energy transfer in a low collisionality plasma with the rate of the energy transfer by collisions. The result shows that the collisionless turbulent energy transfer is a significant energy coupling process for ITER plasma.

  20. Simulated heat waves affected alpine grassland only in combination with drought.

    PubMed

    De Boeck, Hans J; Bassin, Seraina; Verlinden, Maya; Zeiter, Michaela; Hiltbrunner, Erika

    2016-01-01

    The Alpine region is warming fast, and concurrently, the frequency and intensity of climate extremes are increasing. It is currently unclear whether alpine ecosystems are sensitive or resistant to such extremes. We subjected Swiss alpine grassland communities to heat waves with varying intensity by transplanting monoliths to four different elevations (2440-660 m above sea level) for 17 d. Half of these were regularly irrigated while the other half were deprived of irrigation to additionally induce a drought at each site. Heat waves had no significant impacts on fluorescence (Fv /Fm , a stress indicator), senescence and aboveground productivity if irrigation was provided. However, when heat waves coincided with drought, the plants showed clear signs of stress, resulting in vegetation browning and reduced phytomass production. This likely resulted from direct drought effects, but also, as measurements of stomatal conductance and canopy temperatures suggest, from increased high-temperature stress as water scarcity decreased heat mitigation through transpiration. The immediate responses to heat waves (with or without droughts) recorded in these alpine grasslands were similar to those observed in the more extensively studied grasslands from temperate climates. Responses following climate extremes may differ in alpine environments, however, because the short growing season likely constrains recovery.

  1. Simulated heat waves affected alpine grassland only in combination with drought

    NASA Astrophysics Data System (ADS)

    De Boeck, Hans J.; Bassin, Seraina; Verlinden, Maya; Zeiter, Michaela; Hiltbrunner, Erika

    2016-04-01

    The Alpine region is warming fast, leading to an increase in the frequency and intensity of climate extremes. Currently, it is unclear whether alpine ecosystems are sensitive or resistant to such extremes. In an experiment carried out in the Swiss Alps, we subjected Swiss alpine grassland communities to heat waves with varying intensity (5-10 °C warming) by transplanting monoliths to four different elevations (2440-660 m a.s.l.) for 17 days. Half of the monoliths were regularly irrigated while the other half were deprived of irrigation to additionally induce a drought at each site. We found that heat waves had no significant short-term impacts on fluorescence (Fv/Fm, a stress indicator), senescence and aboveground productivity if irrigation was provided. However, when heat waves coincided with drought, plants showed clear signs of stress, resulting in vegetation browning and reduced phytomass production. This likely resulted from direct drought effects, but also, as measurements of stomatal conductance and canopy temperatures suggest, from increased high-temperature stress as water scarcity decreased heat mitigation through transpiration. The immediate responses to heat waves (with or without droughts) recorded in these alpine grasslands were similar to those observed in the more extensively studied grasslands from temperate climates. Climate extreme impacts may differ in the longer run, however, because the short growing season in alpine environments likely constrains recovery.

  2. The effect of heat waves on dairy cow mortality.

    PubMed

    Vitali, A; Felici, A; Esposito, S; Bernabucci, U; Bertocchi, L; Maresca, C; Nardone, A; Lacetera, N

    2015-07-01

    This study investigated the mortality of dairy cows during heat waves. Mortality data (46,610 cases) referred to dairy cows older than 24mo that died on a farm from all causes from May 1 to September 30 during a 6-yr period (2002-2007). Weather data were obtained from 12 weather stations located in different areas of Italy. Heat waves were defined for each weather station as a period of at least 3 consecutive days, from May 1 to September 30 (2002-2007), when the daily maximum temperature exceeded the 90th percentile of the reference distribution (1971-2000). Summer days were classified as days in heat wave (HW) or not in heat wave (nHW). Days in HW were numbered to evaluate the relationship between mortality and length of the wave. Finally, the first 3 nHW days after the end of a heat wave were also considered to account for potential prolonged effects. The mortality risk was evaluated using a case-crossover design. A conditional logistic regression model was used to calculate odds ratio and 95% confidence interval for mortality recorded in HW compared with that recorded in nHW days pooled and stratified by duration of exposure, age of cows, and month of occurrence. Dairy cows mortality was greater during HW compared with nHW days. Furthermore, compared with nHW days, the risk of mortality continued to be higher during the 3 d after the end of HW. Mortality increased with the length of the HW. Considering deaths stratified by age, cows up to 28mo were not affected by HW, whereas all the other age categories of older cows (29-60, 61-96, and >96mo) showed a greater mortality when exposed to HW. The risk of death during HW was higher in early summer months. In particular, the highest risk of mortality was observed during June HW. Present results strongly support the implementation of adaptation strategies which may limit heat stress-related impairment of animal welfare and economic losses in dairy cow farm during HW.

  3. Wave Driven Exothermic Heating in the Mesopause Region

    NASA Technical Reports Server (NTRS)

    Hickey, Michael P.

    1997-01-01

    A full-wave propagation model was developed that describes the propagation of gravity waves from the Earth's surface to the upper boundary, which can be placed anywhere between 150 and 500 km altitude. The model includes a realistic background atmosphere, and includes the effects of mean horizontal winds and their vertical shears, mean vertical temperature gradients, the eddy and molecular diffusion of heat and momentum, and the effects of ion-drag. This model solves five coupled second-order differential equations (continuity, momentum, and energy) in the vertical coordinate to derive the perturbation variables u', v', w' (horizontal and vertical velocity components), T' (temperature) and p' (pressure). The upper boundary can be automatically selected based on tests using the radiation condition at the upper boundary, wherein the height is increased until the wave is experiencing severe dissipation at the upper boundary, ensuring that substantial absorption occurs for any waves reflected from the upper boundary. The determination of wave amplitude is a key requirement of wave energetics. Therefore, the fullwave model has been applied to airglow observations in order to determine wave amplitudes as a function of altitude. This was accomplished by using the full-wave model output to drive a chemistry perturbation module that describes minor species perturbations and the resulting airglow perturbations. The full-wave output was multiplied by an altitude-independent factor such that the modeled and observed relative airglow intensity perturbations were equal. The effects of mean winds were included in these studies, and found to be the most important model input affecting the calculations (being more important than the choice of eddy diffusion profiles and chemical kinetic coefficients). In one study (Hickey et al., 1997a) these winds could not be well estimated from the measurements, whereas in the second study (Hickey et al.,1997b) the mean were well defined with a

  4. The 2010 Russian heat wave was largely predictable

    NASA Astrophysics Data System (ADS)

    Schultz, Colin

    2011-05-01

    From June to August 2010, a stable high-pressure air mass hung in the sky over western Russia. This episode of “atmospheric blocking” drove up temperatures, causing thousands of deaths and breaking temperature records across the country. Strong heat waves like the one in Russia increase their potential to do damage the longer they persist, putting added stress on populations susceptible to dehydration, reduced air quality, and other heat-related illnesses. Long durations of consistently high temperatures also increase the likelihood of drought-driven crop loss and wildfires, both of which devastated the Russian countryside and economy. (Geophysical Research Letters, doi:10.1029/2010GL046557, 2011)

  5. A new way to convert Alfven waves into heat in solar coronal holes - Intermittent magnetic levitation

    NASA Technical Reports Server (NTRS)

    Moore, R. L.; Hammer, R.; Musielak, Z. E.; Suess, S. T.; An, C.-H.

    1992-01-01

    In our recent analysis of Alfven wave reflection in solar coronal holes, we found evidence that coronal holes are heated by reflected Alfven waves. This result suggests that the reflection is inherent to the process that dissipates these Alfven waves into heat. We propose a novel dissipation process that is driven by the reflection, and that plausibly dominates the heating in coronal holes.

  6. Heating by waves in the ion cyclotron frequency range

    SciTech Connect

    Koch, R.

    1996-03-01

    The main aspects of heating with the fast wave in the ion cyclotron range of frequencies (ICRF) are reviewed. First, the ion cyclotron resonance mechanism, fundamental and harmonics, is examined. Then the properties of fast wave dispersion are reviewed, and the principles of minority and higher cylcotron harmonic heating are discussed. An elementary coupling model is worked out in order to outline the computation of the electrical properties of ICRF antennas. Using the simple model, the antenna radiation pattern inside the plasma is computed and the effect of phasing on the k spectrum and on the antenna radiation properties is illustrated. The quasi linear-Fokker-Planck computation of the deformation of distribution functions due to Radio-Frequency (RF) and tail formation are briefly discussed. 11 refs., 5 figs.

  7. Tropical Gravity Wave Momentum Fluxes and Latent Heating Distributions

    NASA Technical Reports Server (NTRS)

    Geller, Marvin A.; Zhou, Tiehan; Love, Peter T.

    2015-01-01

    Recent satellite determinations of global distributions of absolute gravity wave (GW) momentum fluxes in the lower stratosphere show maxima over the summer subtropical continents and little evidence of GW momentum fluxes associated with the intertropical convergence zone (ITCZ). This seems to be at odds with parameterizations forGWmomentum fluxes, where the source is a function of latent heating rates, which are largest in the region of the ITCZ in terms of monthly averages. The authors have examined global distributions of atmospheric latent heating, cloud-top-pressure altitudes, and lower-stratosphere absolute GW momentum fluxes and have found that monthly averages of the lower-stratosphere GW momentum fluxes more closely resemble the monthly mean cloud-top altitudes rather than the monthly mean rates of latent heating. These regions of highest cloud-top altitudes occur when rates of latent heating are largest on the time scale of cloud growth. This, plus previously published studies, suggests that convective sources for stratospheric GW momentum fluxes, being a function of the rate of latent heating, will require either a climate model to correctly model this rate of latent heating or some ad hoc adjustments to account for shortcomings in a climate model's land-sea differences in convective latent heating.

  8. Multivariate Statistical Modelling of Drought and Heat Wave Events

    NASA Astrophysics Data System (ADS)

    Manning, Colin; Widmann, Martin; Vrac, Mathieu; Maraun, Douglas; Bevaqua, Emanuele

    2016-04-01

    Multivariate Statistical Modelling of Drought and Heat Wave Events C. Manning1,2, M. Widmann1, M. Vrac2, D. Maraun3, E. Bevaqua2,3 1. School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, UK 2. Laboratoire des Sciences du Climat et de l'Environnement, (LSCE-IPSL), Centre d'Etudes de Saclay, Gif-sur-Yvette, France 3. Wegener Center for Climate and Global Change, University of Graz, Brandhofgasse 5, 8010 Graz, Austria Compound extreme events are a combination of two or more contributing events which in themselves may not be extreme but through their joint occurrence produce an extreme impact. Compound events are noted in the latest IPCC report as an important type of extreme event that have been given little attention so far. As part of the CE:LLO project (Compound Events: muLtivariate statisticaL mOdelling) we are developing a multivariate statistical model to gain an understanding of the dependence structure of certain compound events. One focus of this project is on the interaction between drought and heat wave events. Soil moisture has both a local and non-local effect on the occurrence of heat waves where it strongly controls the latent heat flux affecting the transfer of sensible heat to the atmosphere. These processes can create a feedback whereby a heat wave maybe amplified or suppressed by the soil moisture preconditioning, and vice versa, the heat wave may in turn have an effect on soil conditions. An aim of this project is to capture this dependence in order to correctly describe the joint probabilities of these conditions and the resulting probability of their compound impact. We will show an application of Pair Copula Constructions (PCCs) to study the aforementioned compound event. PCCs allow in theory for the formulation of multivariate dependence structures in any dimension where the PCC is a decomposition of a multivariate distribution into a product of bivariate components modelled using copulas. A

  9. The 2011 marine heat wave off southwest Australia

    NASA Astrophysics Data System (ADS)

    Rose, T. H.; Smale, D. A.; Botting, G.

    2012-04-01

    Over 2000 km of Western Australian coastline experienced a significant marine heat wave in February and March 2011. Seawater temperature anomalies of +2-4 °C were recorded at a number of locations and satellite-derived SSTs were the highest on record. Here, we present seawater temperatures from southwestern Australia and describe, in detail, the marine climatology of Cockburn Sound; a large, multiple-use coastal embayment. We compared temperature and dissolved oxygen levels in 2011 with data from routine monitoring conducted from 2002-2010. A significant warming event, 2-4 °C in magnitude, persisted for >8 weeks, and seawater temperatures at 10 to 20 m depth were significantly higher than those recorded in the previous 9 yr. Dissolved oxygen levels were depressed at most monitoring sites, being ~2 mg l-1 lower than usual in early March 2011. Ecological responses to short-term extreme events are poorly understood, but evidence from elsewhere along the Western Australian coastline suggests that the heat wave was associated with high rates of coral bleaching, fish, invertebrate and macroalgae mortalities, and algal blooms. However, more ecological information from Cockburn Sound and other multiple-use embayments is urgently needed. The 2011 heat wave provided insights into conditions that may become more prevalent in Cockburn Sound, and elsewhere, if the intensity and frequency of short-term extreme events increases as predicted.

  10. Rayleigh wave inversion using heat-bath simulated annealing algorithm

    NASA Astrophysics Data System (ADS)

    Lu, Yongxu; Peng, Suping; Du, Wenfeng; Zhang, Xiaoyang; Ma, Zhenyuan; Lin, Peng

    2016-11-01

    The dispersion of Rayleigh waves can be used to obtain near-surface shear (S)-wave velocity profiles. This is performed mainly by inversion of the phase velocity dispersion curves, which has been proven to be a highly nonlinear and multimodal problem, and it is unsuitable to use local search methods (LSMs) as the inversion algorithm. In this study, a new strategy is proposed based on a variant of simulated annealing (SA) algorithm. SA, which simulates the annealing procedure of crystalline solids in nature, is one of the global search methods (GSMs). There are many variants of SA, most of which contain two steps: the perturbation of model and the Metropolis-criterion-based acceptance of the new model. In this paper we propose a one-step SA variant known as heat-bath SA. To test the performance of the heat-bath SA, two models are created. Both noise-free and noisy synthetic data are generated. Levenberg-Marquardt (LM) algorithm and a variant of SA, known as the fast simulated annealing (FSA) algorithm, are also adopted for comparison. The inverted results of the synthetic data show that the heat-bath SA algorithm is a reasonable choice for Rayleigh wave dispersion curve inversion. Finally, a real-world inversion example from a coal mine in northwestern China is shown, which proves that the scheme we propose is applicable.

  11. Heat Waves: The Intersection of Climate and Public Health

    NASA Astrophysics Data System (ADS)

    Schindler, J. V.; Grant, F.

    2011-12-01

    Heat waves are deadly weather-related exposures in the U.S. and account for more deaths annually than hurricanes, tornadoes, floods, and earthquakes combined. From a public health perspective, all morbidity and mortality associated with extreme heat events are completely preventable. Related environmental events that can impact health-poor air quality, concentrations of greenhouse gases, and the inability to cool at night-are all expected to increase in severity and frequency over this next century. Northrop Grumman's active program of climate science combines inputs from public health, population health analytics, advanced agent-based modeling and simulation, and high performance computing to assist the characterization of how climate change impacts human health in specific geographies. In this study, we defined heat waves as 3+ consecutive days when the high temperature is 10+ degrees (Fahrenheit) higher than the mean summer high temperature. To address current deficiencies in local planning and decision making with respect to regional climate change and its effect on human health, our research focused on performing a dynamical downscaling with the Weather Research and Forecasting (WRF) model to develop decision aids that translate the regional climate data into actionable information for users. WRF was run in nested mode at spatial resolution of 108 km, 36 km and 12 km and 28 vertical levels. We used WRF simulated temperatures at 2 meters above the surface to calculate the annual average number of days spent in heat waves. Our results indicated a significant increase in heat wave episodes-a direct consequence of steadily increasing maximum temperatures in the future. Our discussion continues with clarification of how public health must become integral to future community, civic, healthcare, and emergency preparedness planning. While continued growth in the number of persons living in urban areas will result in increased exposure to heat-related health risks

  12. On the Variability and Increasing Trends of Heat Waves over India.

    PubMed

    Rohini, P; Rajeevan, M; Srivastava, A K

    2016-01-01

    Over India, heat waves occur during the summer months of April to June. A gridded daily temperature data set for the period, 1961-2013 has been analyzed to examine the variability and trends in heat waves over India. For identifying heat waves, the Excess Heat Factor (EHF) and 90(th) percentile of maximum temperatures were used. Over central and northwestern parts of the country, frequency, total duration and maximum duration of heat waves are increasing. Anomalous persistent high with anti-cyclonic flow, supplemented with clear skies and depleted soil moisture are primarily responsible for the occurrence of heat waves over India. Variability of heat waves over India is influenced by both the tropical Indian Ocean and central Pacific SST anomalies. The warming of the tropical Indian Ocean and more frequent El Nino events in future may further lead to more frequent and longer lasting heat waves over India. PMID:27194567

  13. On the Variability and Increasing Trends of Heat Waves over India.

    PubMed

    Rohini, P; Rajeevan, M; Srivastava, A K

    2016-05-19

    Over India, heat waves occur during the summer months of April to June. A gridded daily temperature data set for the period, 1961-2013 has been analyzed to examine the variability and trends in heat waves over India. For identifying heat waves, the Excess Heat Factor (EHF) and 90(th) percentile of maximum temperatures were used. Over central and northwestern parts of the country, frequency, total duration and maximum duration of heat waves are increasing. Anomalous persistent high with anti-cyclonic flow, supplemented with clear skies and depleted soil moisture are primarily responsible for the occurrence of heat waves over India. Variability of heat waves over India is influenced by both the tropical Indian Ocean and central Pacific SST anomalies. The warming of the tropical Indian Ocean and more frequent El Nino events in future may further lead to more frequent and longer lasting heat waves over India.

  14. On the Variability and Increasing Trends of Heat Waves over India

    PubMed Central

    Rohini, P.; Rajeevan, M.; Srivastava, A. K.

    2016-01-01

    Over India, heat waves occur during the summer months of April to June. A gridded daily temperature data set for the period, 1961–2013 has been analyzed to examine the variability and trends in heat waves over India. For identifying heat waves, the Excess Heat Factor (EHF) and 90th percentile of maximum temperatures were used. Over central and northwestern parts of the country, frequency, total duration and maximum duration of heat waves are increasing. Anomalous persistent high with anti-cyclonic flow, supplemented with clear skies and depleted soil moisture are primarily responsible for the occurrence of heat waves over India. Variability of heat waves over India is influenced by both the tropical Indian Ocean and central Pacific SST anomalies. The warming of the tropical Indian Ocean and more frequent El Nino events in future may further lead to more frequent and longer lasting heat waves over India. PMID:27194567

  15. Reduced soil moisture contributes to more intense and more frequent heat waves in northern China

    NASA Astrophysics Data System (ADS)

    Zhang, Jie; Liu, Zhenyuan; Chen, Li

    2015-09-01

    Heat waves have attracted increasing attention in recent years due to their frequent occurrence. The present study investigates the heat wave intensity and duration in China using daily maximum temperature from 753 weather stations from 1960 to 2010. In addition, its relationships with soil moisture local forcing on the ten-day period and monthly scales in spring and summer are analyzed using soil moisture data from weather stations and ERA40 reanalysis data. And finally, a mechanistic analysis is carried out using CAM5.1 (Community Atmosphere Model, version 5.1) coupled with CLM2 (Community Land Model, version 2). It is found that the heat wave frequency and duration show a sandwich distribution across China, with high occurrence rates in Southeast China and Northwest China, where the maximum frequency and duration exceeded 2.1 times and 9 days per year, respectively. The increasing trends in both duration and intensity occurred to the north of 35°N. The relationships between heat wave frequency in northern China in July (having peak distribution) and soil moisture in the earlier stage (from March to June) and corresponding period (July) are further analyzed, revealing a strong negative correlation in March, June and July, and thus showing that soil moisture in spring and early summer could be an important contributor to heat waves in July via positive subtropical high anomalies. However, the time scales of influence were relatively short in the semi-humid and humid regions, and longer in the arid region. The contribution in the corresponding period took place via positive subtropical high anomalies and positive surface skin temperature and sensible heat flux anomalies.

  16. HeatWave: the next generation of thermography devices

    NASA Astrophysics Data System (ADS)

    Moghadam, Peyman; Vidas, Stephen

    2014-05-01

    Energy sustainability is a major challenge of the 21st century. To reduce environmental impact, changes are required not only on the supply side of the energy chain by introducing renewable energy sources, but also on the demand side by reducing energy usage and improving energy efficiency. Currently, 2D thermal imaging is used for energy auditing, which measures the thermal radiation from the surfaces of objects and represents it as a set of color-mapped images that can be analysed for the purpose of energy efficiency monitoring. A limitation of such a method for energy auditing is that it lacks information on the geometry and location of objects with reference to each other, particularly across separate images. Such a limitation prevents any quantitative analysis to be done, for example, detecting any energy performance changes before and after retrofitting. To address these limitations, we have developed a next generation thermography device called Heat Wave. Heat Wave is a hand-held 3D thermography device that consists of a thermal camera, a range sensor and color camera, and can be used to generate precise 3D model of objects with augmented temperature and visible information. As an operator holding the device smoothly waves it around the objects of interest, Heat Wave can continuously track its own pose in space and integrate new information from the range and thermal and color cameras into a single, and precise 3D multi-modal model. Information from multiple viewpoints can be incorporated together to improve the accuracy, reliability and robustness of the global model. The approach also makes it possible to reduce any systematic errors associated with the estimation of surface temperature from the thermal images.

  17. Protoplanetary Disk Heating and Evolution Driven by Spiral Density Waves

    NASA Astrophysics Data System (ADS)

    Rafikov, Roman R.

    2016-11-01

    Scattered light imaging of protoplanetary disks often reveals prominent spiral arms, likely excited by massive planets or stellar companions. Assuming that these arms are density waves, evolving into spiral shocks, we assess their effect on the thermodynamics, accretion, and global evolution of the disk. We derive analytical expressions for the direct (irreversible) heating, angular momentum transport, and mass accretion rate induced by disk shocks of arbitrary amplitude. These processes are very sensitive to the shock strength. We show that waves of moderate strength (density jump at the shock ΔΣ/Σ ∼ 1) result in negligible disk heating (contributing at the ∼1% level to the energy budget) in passive, irradiated protoplanetary disks on ∼100 au scales, but become important within several au. However, shock heating is a significant (or even dominant) energy source in disks of cataclysmic variables, stellar X-ray binaries, and supermassive black hole binaries, heated mainly by viscous dissipation. Mass accretion induced by the spiral shocks is comparable to (or exceeds) the mass inflow due to viscous stresses. Protoplanetary disks featuring prominent global spirals must be evolving rapidly, in ≲0.5 Myr at ∼100 au. A direct upper limit on the evolution timescale can be established by measuring the gravitational torque due to the spiral arms from the imaging data. We find that, regardless of their origin, global spiral waves must be important agents of the protoplanetary disk evolution. They may serve as an effective mechanism of disk dispersal and could be related to the phenomenon of transitional disks.

  18. An approach to quantify the heat wave strength and price a heat derivative for risk hedging

    NASA Astrophysics Data System (ADS)

    Shen, Samuel S. P.; Kramps, Benedikt; Sun, Shirley X.; Bailey, Barbara

    2012-01-01

    Mitigating the heat stress via a derivative policy is a vital financial option for agricultural producers and other business sectors to strategically adapt to the climate change scenario. This study has provided an approach to identifying heat stress events and pricing the heat stress weather derivative due to persistent days of high surface air temperature (SAT). Cooling degree days (CDD) are used as the weather index for trade. In this study, a call-option model was used as an example for calculating the price of the index. Two heat stress indices were developed to describe the severity and physical impact of heat waves. The daily Global Historical Climatology Network (GHCN-D) SAT data from 1901 to 2007 from the southern California, USA, were used. A major California heat wave that occurred 20-25 October 1965 was studied. The derivative price was calculated based on the call-option model for both long-term station data and the interpolated grid point data at a regular 0.1°×0.1° latitude-longitude grid. The resulting comparison indicates that (a) the interpolated data can be used as reliable proxy to price the CDD and (b) a normal distribution model cannot always be used to reliably calculate the CDD price. In conclusion, the data, models, and procedures described in this study have potential application in hedging agricultural and other risks.

  19. Millimeter waves as a source of selective heating of skin.

    PubMed

    Zhadobov, Maxim; Alekseev, Stanislav I; Le Dréan, Yves; Sauleau, Ronan; Fesenko, Evgeny E

    2015-09-01

    This study demonstrates that 20-100 GHz range can be used for spatially-accurate focusing of heating inside the skin achieved by varying frequency and exposure beam size, as well as by enforcing air convection. The latter is also used to reduce overheating of skin surface. Heating at different skin depths depending on these parameters is investigated in detail using the hybrid bio-heat equation. In particular, it is shown that decreasing frequency and/or increasing exposure beam size at forced airflow result in elevation of heating of deeper layers of tissue and decrease of skin surface temperature. Changes of water content within 15%, which exceed those due to aging and presence of tumors, only slightly affect heating. Exposure intensity necessary to reach a target temperature significantly increases in different areas of body with elevated blood flow. Dependence on exposure intensity and hyperthermia treatment duration is also investigated and discussed. Results of this study suggest that the lower part of the millimeter-wave range is an attractive alternative for non-invasive thermal treatment of skin cancer with a high spatial resolution. PMID:26179286

  20. Millimeter waves as a source of selective heating of skin.

    PubMed

    Zhadobov, Maxim; Alekseev, Stanislav I; Le Dréan, Yves; Sauleau, Ronan; Fesenko, Evgeny E

    2015-09-01

    This study demonstrates that 20-100 GHz range can be used for spatially-accurate focusing of heating inside the skin achieved by varying frequency and exposure beam size, as well as by enforcing air convection. The latter is also used to reduce overheating of skin surface. Heating at different skin depths depending on these parameters is investigated in detail using the hybrid bio-heat equation. In particular, it is shown that decreasing frequency and/or increasing exposure beam size at forced airflow result in elevation of heating of deeper layers of tissue and decrease of skin surface temperature. Changes of water content within 15%, which exceed those due to aging and presence of tumors, only slightly affect heating. Exposure intensity necessary to reach a target temperature significantly increases in different areas of body with elevated blood flow. Dependence on exposure intensity and hyperthermia treatment duration is also investigated and discussed. Results of this study suggest that the lower part of the millimeter-wave range is an attractive alternative for non-invasive thermal treatment of skin cancer with a high spatial resolution.

  1. PBX-M ion Bernstein wave heating overview

    SciTech Connect

    Ono, M.; Chu, T.K.; Hermann, H.; LeBlanc, B.; Tighe, W.; Bell, R.; Bernabei, S.; Hatcher, R.; Kaita, R.; Kaye, S.; Kugel, H.; Okabayashi, M.; Oliver, H.; Paul, S.; Sauthoff, N.; Sesnic, S.; Takahashi, H. . Plasma Physics Lab.); Cesario, R. ); Seki, T. ); Asakura, N. (Japan Atomic Energy Research Inst., To

    1993-01-01

    A high power ion Bernstein wave heating system has been introduced on PBX-M for heating and for controlling the plasma pressure profile in an effort to achieve the stable high beta second stability'' regime. The pressure profile can be controlled through local bulk ion heating as well as density profile control. In bean-shaped plasmas with plasma currents range from 180 kA to 250 kA, good ion heating up to the highest, applied rf power, ([approx]700 kW) has been observed. The observed broadening of the ion temperature profile is consistent with localized off-axis bulk ion heating as predicted by IBW ray tracing calculations. Application of IBW also resulted in a greatly modified density profile. The ability for IBW to change the density profile appears to be particularly attractive for controlling the bootstrap current profile for advanced tokamaks. Many important IBWH-related edge physics results were also obtained, including ponderomotive edge plasma modification and parametric instability onset conditions. The experimental plan for the next IBW run includes investigation of synergy with LHCD, attainment of high bootstrap current fraction discharges utilizing the IBW density profile control, and exploration of high beta plasma regimes.

  2. PBX-M ion Bernstein wave heating overview

    SciTech Connect

    Ono, M.; Chu, T.K.; Hermann, H.; LeBlanc, B.; Tighe, W.; Bell, R.; Bernabei, S.; Hatcher, R.; Kaita, R.; Kaye, S.; Kugel, H.; Okabayashi, M.; Oliver, H.; Paul, S.; Sauthoff, N.; Sesnic, S.; Takahashi, H.; Cesario, R.; Seki, T.; Asakura, N.; Blush, L.; Conn, R.; Doerner, R.; Grossman, A.; Schmitz, L.; Tynan, G.; Dunlap, J.; England, A.; Harris, J.; Isler, R.; Paoletti, F.

    1993-04-01

    A high power ion Bernstein wave heating system has been introduced on PBX-M for heating and for controlling the plasma pressure profile in an effort to achieve the stable high beta ``second stability`` regime. The pressure profile can be controlled through local bulk ion heating as well as density profile control. In bean-shaped plasmas with plasma currents range from 180 kA to 250 kA, good ion heating up to the highest, applied rf power, ({approx}700 kW) has been observed. The observed broadening of the ion temperature profile is consistent with localized off-axis bulk ion heating as predicted by IBW ray tracing calculations. Application of IBW also resulted in a greatly modified density profile. The ability for IBW to change the density profile appears to be particularly attractive for controlling the bootstrap current profile for advanced tokamaks. Many important IBWH-related edge physics results were also obtained, including ponderomotive edge plasma modification and parametric instability onset conditions. The experimental plan for the next IBW run includes investigation of synergy with LHCD, attainment of high bootstrap current fraction discharges utilizing the IBW density profile control, and exploration of high beta plasma regimes.

  3. Mortality in Spain during the heat waves of summer 2003.

    PubMed

    Simón, F; Lopez-Abente, G; Ballester, E; Martínez, F

    2005-07-01

    The effect of the elevated temperatures on mortality experienced in Europe during the summer of 2003 was observed in several countries. This study, carried out in Spain, describes mortality between 1 June and 31 August and evaluates the effect of the heat wave on mortality. Observed deaths were obtained from official death registers from 50 provincial capitals. Observed deaths were compared with the expected number, estimated by applying a Poisson regression model to historical mortality series and adjusting for the upward trend and seasonality observed. Meteorological information was provided by the Instituto Nacional de Meteorologia (National Institute of Meteorology). Spain experienced three heat waves in 2003. The total associated excess deaths were 8% (43 212 observed deaths compared with 40 046 expected deaths). Excess deaths were only observed in those aged 75 years and over (15% more deaths than expected for the age group 75 to 84 and 29% for those aged 85 or over). This phenomenon (heat-associated excess mortality) is an emerging public health problem because of its increasing attributable risk, the aging of the Spanish population and its forecasted increasing frequency due to global warming. The implementation of alert and response systems based on monitoring of climate-related risks, emergency room activity and mortality, and strengthening the response capacity of the social and health services should be considered.

  4. Observations of Stochastic Ion Heating by Low - Drift Waves.

    NASA Astrophysics Data System (ADS)

    McChesney, Jon Mearns

    Several laser induced fluorescence (LIF) experiments were performed on the Encore tokamak device. These experiments represent the first application of this technique to the majority ions of a tokamak. The LIF technique allowed the Doppler-broadened, ion distribution function to be scanned with high resolution, giving accurate ion temperature measurements. As a preliminary test, the diagnostic was used to observe ion heating in the presence of lower hybrid RF power. Ion temperatures were found to increase dramatically with increasing RF power. By using a second dye laser, actual ion trajectories were determined using the technique of "optical tagging." Tagging involves the use of a so-called "pump" laser to alter the fraction of ions in a particular quantum state. As a preliminary test, this technique was used to demonstrate ion gyro-motion in Encore. Using the ion distribution functions determined by means of LIF, it was possible to make detailed measurements of ion heating during an ohmically heated tokamak discharge. It was found that the observed rate of ion heating was nearly two orders of magnitude faster than expected from collisional energy exchange with the hot electrons. These high ion temperatures were later verified by measuring the Landau damping of ion acoustic waves. The observed damping lengths were roughly in accord with those calculated using measured values of T_{e} and T _{i}. This enhanced ion heating was correlated with the presence of large amplitude, low frequency ( omega < omega _{ci}), drift-Alfven waves. Using numerical calculations, it was shown, that in the presence of electrostatic modes of sufficient amplitude, ion motion becomes stochastic. In physical terms, stochasticity occurs when the ion displacement that is due to the polarization drift becomes comparable to the perpendicular wavelength, i.e., when alpha = m_ {i}k_sp{|}{2} phi_0/qB_sp{0}{2} ~ 1. A combination of numerical calculations and experiments were used to demonstrate

  5. Fast wave heating in the NSTX-Upgrade device

    SciTech Connect

    Bertelli, Nicola; Jaeger, E. F.; Berry, Lee Alan; Bonoli, P.; Budny, R. V.; Fu, GuoYong; Gerhardt, S.; Green, David L; Harvey, R. W.; Hosea, J.; Kramer, G.; LeBlanc, B; Perkins, R. J.; Phillips, C. K.; Ryan, Philip Michael; Taylor, G.; Valeo, E. J.; Wilson, J. R.; Wright, J.

    2013-01-01

    NSTX-Upgrade will operate with toroidal magnetic fields (B T) up to 1 T, nearly twice the value used in the experiments on NSTX, and the available NBI power will be doubled. The doubling of B T while retaining the 30 MHz RF source frequency has moved the heating regime from the high harmonic fast wave (HHFW) regime used in NSTX to the mid harmonic fast wave (MHFW) regime. By making use of the full wave code AORSA, this work shows that direct ion damping (mainly by thermal ions localized at the 5th harmonic resonance) might be significant in NSTX-Upgrade under TRANSP predicted full performance conditions and the electron and ion absorption is sensitive to the ratio of electron and ion temperature. Launching at high toroidal wave number appears to be one way to significantly reduce the ion damping. By using the extended AORSA code, which includes a detailed description of the scrape-off layer in the field solutions, we found a large electric field amplitude outside of the last closed flux surface as previously seen in NSTX from AORSA simulations (D. L. Green, et al, Phys. Rev. Lett. 107, 145001 (2011)). Preliminary results by introducing a collision damping in the scrape-off layer in the AORSA code to represent a damping process are presented, showing for the first time absorbed power in the scrape-off layer.

  6. Fast wave heating in the NSTX-Upgrade device

    NASA Astrophysics Data System (ADS)

    Bertelli, N.; Jaeger, E. F.; Berry, L.; Bonoli, P. T.; Budny, R.; Fu, G.-Y.; Gerhardt, S.; Green, D. L.; Harvey, R. W.; Hosea, J. C.; Kramer, G. J.; LeBlanc, B.; Perkins, R. J.; Phillips, C. K.; Ryan, P.; Taylor, G.; Valeo, E. J.; Wilson, J. R.; Wright, J. C.

    2014-02-01

    NSTX-Upgrade will operate with toroidal magnetic fields (BT) up to 1 T, nearly twice the value used in the experiments on NSTX, and the available NBI power will be doubled. The doubling of BT while retaining the 30 MHz RF source frequency has moved the heating regime from the high harmonic fast wave (HHFW) regime used in NSTX to the mid harmonic fast wave (MHFW) regime. By making use of the full wave code AORSA, this work shows that direct ion damping (mainly by thermal ions localized at the 5th harmonic resonance) might be significant in NSTX-Upgrade under TRANSP predicted full performance conditions and the electron and ion absorption is sensitive to the ratio of electron and ion temperature. Launching at high toroidal wave number appears to be one way to significantly reduce the ion damping. By using the extended AORSA code, which includes a detailed description of the scrape-off layer in the field solutions, we found a large electric field amplitude outside of the last closed flux surface as previously seen in NSTX from AORSA simulations (D. L. Green, et al, Phys. Rev. Lett. 107, 145001 (2011)). Preliminary results by introducing a collision damping in the scrape-off layer in the AORSA code to represent a damping process are presented, showing for the first time absorbed power in the scrape-off layer.

  7. Fast wave heating in the NSTX-Upgrade device

    SciTech Connect

    Bertelli, N.; Budny, R.; Fu, G.-Y.; Gerhardt, S.; Hosea, J. C.; Kramer, G. J.; LeBlanc, B.; Perkins, R. J.; Phillips, C. K.; Taylor, G.; Valeo, E. J.; Wilson, J. R.; Jaeger, E. F.; Berry, L.; Green, D. L.; Ryan, P.; Bonoli, P. T.; Wright, J. C.; Harvey, R. W.

    2014-02-12

    NSTX-Upgrade will operate with toroidal magnetic fields (B{sub T}) up to 1 T, nearly twice the value used in the experiments on NSTX, and the available NBI power will be doubled. The doubling of B{sub T} while retaining the 30 MHz RF source frequency has moved the heating regime from the high harmonic fast wave (HHFW) regime used in NSTX to the mid harmonic fast wave (MHFW) regime. By making use of the full wave code AORSA, this work shows that direct ion damping (mainly by thermal ions localized at the 5th harmonic resonance) might be significant in NSTX-Upgrade under TRANSP predicted full performance conditions and the electron and ion absorption is sensitive to the ratio of electron and ion temperature. Launching at high toroidal wave number appears to be one way to significantly reduce the ion damping. By using the extended AORSA code, which includes a detailed description of the scrape-off layer in the field solutions, we found a large electric field amplitude outside of the last closed flux surface as previously seen in NSTX from AORSA simulations (D. L. Green, et al, Phys. Rev. Lett. 107, 145001 (2011)). Preliminary results by introducing a collision damping in the scrape-off layer in the AORSA code to represent a damping process are presented, showing for the first time absorbed power in the scrape-off layer.

  8. Analytic and numerical models of wave-CISK with conditional heating

    NASA Technical Reports Server (NTRS)

    Crum, Francis X.; Dunkerton, Timothy J.

    1992-01-01

    Wave-CISK with conditional heating is investigated in the equatorial zonal-height plane by analytic and numerical techniques. For two- and three-level models, previous results are extended to give additional evidence that the most unstable mode has a single wet region of infinitesimal width. A three-level model has qualitatively similar behavior as the two-level model except that propagating solutions are possible due to coalescence of internal vertical modes. Phase speeds with conditional heating are found to be slightly greater than those for unconditional heating. The structure has one circulation cell in the vertical and is asymmetric in longitude with stronger motion on the leading edge. Growth rate is inversely proportional to the width of the single wet region. That width can be limited by second-order diffusion. A general integral relationship between growth rate, viscosity, phase speed, and heating is derived. The main conclusion is that the linear wave-CISK catastrophe is modified by conditional heating but not eliminated. The preferred mode of instability has one wet region, but it occurs on the smallest possible scale. It is likely that numerical models that use conditional heating are sensitive to resolution, especially for the commonly used spectral truncations, unless there is sufficiently strong damping at the smallest scales.

  9. Global assessment of heat wave magnitudes from 1901 to 2010 and implications for the river discharge of the Alps.

    PubMed

    Zampieri, Matteo; Russo, Simone; di Sabatino, Silvana; Michetti, Melania; Scoccimarro, Enrico; Gualdi, Silvio

    2016-11-15

    Heat waves represent one of the most significant climatic stressors for ecosystems, economies and societies. A main topic of debate is whether they have increased or not in intensity and/or their duration due to the observed climate change. Firstly, this is because of the lack of reliable long-term daily temperature data at the global scale; secondly, because of the intermittent nature of such phenomena. Long datasets are required to produce a reliable and meaningful assessment. In this study, we provide a global estimate of heat wave magnitudes based on the three most appropriate datasets currently available, derived from models and observations (i.e. the 20th Century Reanalyses from NOAA and ECMWF), spanning the last century and before. The magnitude of the heat waves is calculated by means of the Heat Wave Magnitude Index daily (HWMId), taking into account both duration and amplitude. We compare the magnitude of the most severe heat waves occurred across different regions of the world and we discuss the decadal variability of the larger events since the 1850s. We concentrate our analysis from 1901 onwards, where all datasets overlap. Our results agree with other studies focusing on heat waves that have occurred in the recent decades, but using different data. In addition, we found that the percentage of global area covered by heat wave exceeding a given magnitude has increased almost three times, in the last decades, with respect to that measured in the early 20th century. Finally, we discuss the specific implications of the heat waves on the river runoff generated in the Alps, for which comparatively long datasets exist, affecting the water quality and availability in a significant portion of the European region in summer.

  10. Global assessment of heat wave magnitudes from 1901 to 2010 and implications for the river discharge of the Alps.

    PubMed

    Zampieri, Matteo; Russo, Simone; di Sabatino, Silvana; Michetti, Melania; Scoccimarro, Enrico; Gualdi, Silvio

    2016-11-15

    Heat waves represent one of the most significant climatic stressors for ecosystems, economies and societies. A main topic of debate is whether they have increased or not in intensity and/or their duration due to the observed climate change. Firstly, this is because of the lack of reliable long-term daily temperature data at the global scale; secondly, because of the intermittent nature of such phenomena. Long datasets are required to produce a reliable and meaningful assessment. In this study, we provide a global estimate of heat wave magnitudes based on the three most appropriate datasets currently available, derived from models and observations (i.e. the 20th Century Reanalyses from NOAA and ECMWF), spanning the last century and before. The magnitude of the heat waves is calculated by means of the Heat Wave Magnitude Index daily (HWMId), taking into account both duration and amplitude. We compare the magnitude of the most severe heat waves occurred across different regions of the world and we discuss the decadal variability of the larger events since the 1850s. We concentrate our analysis from 1901 onwards, where all datasets overlap. Our results agree with other studies focusing on heat waves that have occurred in the recent decades, but using different data. In addition, we found that the percentage of global area covered by heat wave exceeding a given magnitude has increased almost three times, in the last decades, with respect to that measured in the early 20th century. Finally, we discuss the specific implications of the heat waves on the river runoff generated in the Alps, for which comparatively long datasets exist, affecting the water quality and availability in a significant portion of the European region in summer. PMID:27418520

  11. Unsteady Heat-Flux Measurements of Second-Mode Instability Waves in a Hypersonic Boundary Layer

    NASA Technical Reports Server (NTRS)

    Kergerise, Michael A.; Rufer, Shann J.

    2016-01-01

    In this paper we report on the application of the atomic layer thermopile (ALTP) heat- flux sensor to the measurement of laminar-to-turbulent transition in a hypersonic flat plate boundary layer. The centerline of the flat-plate model was instrumented with a streamwise array of ALTP sensors and the flat-plate model was exposed to a Mach 6 freestream over a range of unit Reynolds numbers. Here, we observed an unstable band of frequencies that are associated with second-mode instability waves in the laminar boundary layer that forms on the flat-plate surface. The measured frequencies, group velocities, phase speeds, and wavelengths of these instability waves are in agreement with data previously reported in the literature. Heat flux time series, and the Morlet-wavelet transforms of them, revealed the wave-packet nature of the second-mode instability waves. In addition, a laser-based radiative heating system was developed to measure the frequency response functions (FRF) of the ALTP sensors used in the wind tunnel test. These measurements were used to assess the stability of the sensor FRFs over time and to correct spectral estimates for any attenuation caused by the finite sensor bandwidth.

  12. Additional Radiative Cooling of the Mesopause Region due to Small-Scale Temperature Fluctuations Associated with Gravity Waves

    NASA Astrophysics Data System (ADS)

    Kutepov, A.; Feofilov, A.; Medvedev, A.; Pauldrach, A.; Hartogh, P.

    2008-05-01

    We address a previously unknown effect of the radiative cooling of the mesosphere and lower thermosphere (MLT) produced by small-scale irregular temperature fluctuations (ITFs) associated with gravity waves. These disturbances are not resolved by present GCMs, but they alter the radiative transfer and the heating/cooling rates significantly. We apply a statistical model of gravity waves superimposed on large-scale temperature profiles, and perform direct calculations of the radiative cooling/heating in the MLT in the IR bands of CO2, O3 and H2O molecules taking into account the breakdown of the local thermodynamic equilibrium (non-LTE). We found that in the periods of strong wave activity the subgrid ITFs can cause an additional cooling up to 3 K/day near the mesopause. The effect is produced mainly by the fundamental 15 μm band of the main CO2 isotope. We derived a simple expression for the correction to mean (resolved by GCMs) temperature profiles using the variance of the temperature perturbations to account for the additional cooling effect. The suggested parameterization can be applied in GCMs in conjunction with existing gravity wave drag parameterizations.

  13. Traveling wave antenna for fast wave heating and current drive in tokamaks

    SciTech Connect

    Ikezi, H.; Phelps, D.A.

    1995-07-01

    The traveling wave antenna for heating and current drive in the ion cyclotron range of frequencies is shown theoretically to have loading and wavenumber spectrum which are largely independent of plasma conditions. These characteristics have been demonstrated in low power experiments on the DIII-D tokamak, in which a standard four-strap antenna was converted to a traveling wave antenna through use of external coupling elements. The experiments indicate that the array maintains good impedance matching without dynamic tuning during abrupt changes in the plasma, such as during L- to H-mode transitions, edge localized mode activity, and disruptions. An analytic model was developed which exhibits the features observed in the experiments. Guidelines for the design of traveling wave antennas are derived from the validated model.

  14. Deadly 2010 Russian heat wave not a consequence of climate change

    NASA Astrophysics Data System (ADS)

    Schultz, Colin

    2011-05-01

    Although some people may try to ascribe specific extreme weather events to climate change, global warming cannot be held responsible for recent weather events such as the 2010 Russian heat wave. Using climate simulations and a comparison against historical conditions, Dole et al. assess the influence of greenhouse gases, aerosols, anomalous sea surface temperatures, and other potential climate forcings on the likelihood and magnitude of the 2010 Russian heat wave. The authors suggest that the heat wave—which lasted from late June to mid­August and was responsible for thousands of deaths, widespread wildfires, and devastating crop loss—fell well within the bounds of natural climate variability. The authors find that none of the tested climate factors showed appreciable ability to predict the extreme temperatures seen throughout the heat wave. Additionally, the researchers' historical analysis revealed that July temperatures, as well as the temperature variability, for the affected region of western Russia showed no significant trend over the past 130 years. They note that the top 10 hottest July days for the region were distributed randomly across the historical period, although global averages do show clustering in the past 2 decades. (Geophysical Research Letters, doi:10.1029/2010GL046582, 2011)

  15. Impact of heat waves on mortality in Croatia.

    PubMed

    Zaninović, Ksenija; Matzarakis, Andreas

    2014-08-01

    The aim of this work was to determine the criteria for heat loads associated with an increase in mortality in different climatic regions of Croatia. The relationship between heat stress and mortality was analysed for the period 1983-2008. The input series is excess mortality defined as the deviations of mortality from expected values determined by means of a Gaussian filter of 183 days. The assessment of the thermal environment was performed by means of physiologically equivalent temperature (PET). The curve depicting the relationship between mortality and temperature has a U shape, with increased mortality in both the cold and warm parts of the scale but more pronounced in the warm part. The threshold temperature for increased mortality was determined using a scatter plot and fitting data by means of moving average of mortality; the latter is defined as the temperature at which excess mortality becomes significant. The values are higher in the continental part of Croatia than at the coast due to the refreshing influence of the sea during the day. The same analysis on a monthly basis shows that at the beginning of the warm season increased mortality occurs at a lower temperature compared with later on in the summer, and the difference is up to 15 °C between August and April. The increase in mortality is highest during the first 3-5 days and after that it decreases and falls below the expected value. Long-lasting heat waves present an increased risk, but in very long heat waves the increase in mortality is reduced due to mortality displacement.

  16. Impact of heat waves on mortality in Croatia

    NASA Astrophysics Data System (ADS)

    Zaninović, Ksenija; Matzarakis, Andreas

    2014-08-01

    The aim of this work was to determine the criteria for heat loads associated with an increase in mortality in different climatic regions of Croatia. The relationship between heat stress and mortality was analysed for the period 1983-2008. The input series is excess mortality defined as the deviations of mortality from expected values determined by means of a Gaussian filter of 183 days. The assessment of the thermal environment was performed by means of physiologically equivalent temperature (PET). The curve depicting the relationship between mortality and temperature has a U shape, with increased mortality in both the cold and warm parts of the scale but more pronounced in the warm part. The threshold temperature for increased mortality was determined using a scatter plot and fitting data by means of moving average of mortality; the latter is defined as the temperature at which excess mortality becomes significant. The values are higher in the continental part of Croatia than at the coast due to the refreshing influence of the sea during the day. The same analysis on a monthly basis shows that at the beginning of the warm season increased mortality occurs at a lower temperature compared with later on in the summer, and the difference is up to 15 °C between August and April. The increase in mortality is highest during the first 3-5 days and after that it decreases and falls below the expected value. Long-lasting heat waves present an increased risk, but in very long heat waves the increase in mortality is reduced due to mortality displacement.

  17. Effects of simulated heat waves on cardiovascular functions in senile mice.

    PubMed

    Zhang, Xiakun; Lu, Jing; Zhang, Shuyu; Wang, Chunling; Wang, Baojian; Guo, Pinwen; Dong, Lina

    2014-08-01

    The mechanism of the effects of simulated heat waves on cardiovascular disease in senile mice was investigated. Heat waves were simulated in a TEM1880 meteorological environment simulation chamber, according to a heat wave that occurred in July 2001 in Nanjing, China. Eighteen senile mice were divided into control, heat wave, and heat wave BH4 groups, respectively. Mice in the heat wave and heat wave BH4 groups were exposed to simulated heat waves in the simulation chamber. The levels of ET-1, NO, HSP60, SOD, TNF, sICAM-1, and HIF-1α in each group of mice were measured after heat wave simulation. Results show that heat waves decreased SOD activity in the myocardial tissue of senile mice, increased NO, HSP60, TNF, sICAM-1, and HIF-1α levels, and slightly decreased ET-1 levels, BH4 can relieve the effects of heat waves on various biological indicators. After a comprehensive analysis of the experiments above, we draw the followings conclusions regarding the influence of heat waves on senile mice: excess HSP60 activated immune cells, and induced endothelial cells and macrophages to secrete large amounts of ICAM-1, TNF-α, and other inflammatory cytokines, it also activated the inflammation response in the body and damaged the coronary endothelial cell structure, which increased the permeability of blood vessel intima and decreased SOD activity in cardiac tissues. The oxidation of lipoproteins in the blood increased, and large amounts of cholesterol were generated. Cholesterol penetrated the intima and deposited on the blood vessel wall, forming atherosclerosis and leading to the occurrence of cardiovascular disease in senile mice. These results maybe are useful for studying the effects of heat waves on elderly humans, which we discussed in the discussion chapter. PMID:25101768

  18. Perpendicular heating of electrons by upper hybrid waves generated by a ring distribution

    NASA Technical Reports Server (NTRS)

    Lin, C. S.; Menietti, J. D.; Wong, H. K.

    1990-01-01

    Satellite observations of electron conical distributions with enhanced fluxes just outside the loss cone suggest that telectrons have been heated perpendicularly to the magnetic field in the mid-altitude polar magnetosphere. To understand electron conical distributions, plasma simulations are conducted to examine an upper hybrid wave instability of a ring electron distribution perpendicular to the magnetic field in a cold electron background. The simulations indicate that both the cold and ring distributions are heated perpendicularly during the saturation stage. From the plasma data, a ring distribution can be identified as a trapped distribution function with an enhancement near 90-deg pitch angle in the phase space density plot. It is suggested that the ring distribution might provide an additional free energy source for generating upper hybrid waves associated with electron conical events.

  19. Effects of Heat and Momentum Addition Inside and Outside the Compound Sonic Point of the Solar Wind

    NASA Astrophysics Data System (ADS)

    Hu, Q.; Webb, G. M.; McKenzie, J. F.

    2014-12-01

    We consider the effect of heat and momentum addition to the solar wind for a model including the effects of Alfven waves and plasma pressure (proton plus electron pressure). The mass flux per unit area in 1D flow maximizes when the flow speed equals the compound sound speed, including the effects of the Alfven wave pressure. We discuss the analogue of the Laval nozzle for the solar wind flow, and the dependence of the effective nozzle area as a function of radial distance, and the relationship of the nozzle area to the momentum equation and the Mach number of the flow. An analysis is carried out of the effects of heat and momentum addition to the wind, using a thin slice approximation, which leads to Rankine Hugoniot relations for weak deflagrations and detonations (i.e. the combustion Hugoniot). The linearized Hugoniot is used to analyze the effects of small momentum and energy addition to the wind in the thin slice approximation. We obtain the fully nonlinear Rankine Hugoniot equation solutions. The analysis also holds in the presence of Alfven waves, in which the wave energy exchange equation yields the wave action flux conservation law when their contribution to the compound sound speed is taken into account. The effective polytropic index γgamma and flow speed relative to the compound flow speed ahead of the slice play crucial roles in determining whether local acceleration or deceleration results. Some results are at first sight unexpected since γgamma for Alfven waves ranges from -1/2 (in sub-Alfvenic flow) to 3/2 in super-Alfvenic flow.

  20. Chromospheric Heating by Acoustic Waves Compared to Radiative Cooling

    NASA Astrophysics Data System (ADS)

    Sobotka, M.; Heinzel, P.; Švanda, M.; Jurčák, J.; del Moro, D.; Berrilli, F.

    2016-07-01

    Acoustic and magnetoacoustic waves are among the possible candidate mechanisms that heat the upper layers of the solar atmosphere. A weak chromospheric plage near the large solar pore NOAA 11005 was observed on 2008 October 15, in the Fe i 617.3 nm and Ca ii 853.2 nm lines of the Interferometric Bidimemsional Spectrometer attached to the Dunn Solar Telescope. In analyzing the Ca ii observations (with spatial and temporal resolutions of 0.″4 and 52 s) the energy deposited by acoustic waves is compared to that released by radiative losses. The deposited acoustic flux is estimated from the power spectra of Doppler oscillations measured in the Ca ii line core. The radiative losses are calculated using a grid of seven one-dimensional hydrostatic semi-empirical model atmospheres. The comparison shows that the spatial correlation of the maps of radiative losses and acoustic flux is 72%. In a quiet chromosphere, the contribution of acoustic energy flux to radiative losses is small, only about 15%. In active areas with a photospheric magnetic-field strength between 300 and 1300 G and an inclination of 20°-60°, the contribution increases from 23% (chromospheric network) to 54% (a plage). However, these values have to be considered as lower limits and it might be possible that the acoustic energy flux is the main contributor to the heating of bright chromospheric network and plages.

  1. The Impact of Heat Islands on Mortality in Paris during the August 2003 Heat Wave

    PubMed Central

    Zeghnoun, Abdelkrim; Dousset, Bénédicte; Bretin, Philippe; Vandentorren, Stéphanie; Giraudet, Emmanuel; Beaudeau, Pascal

    2011-01-01

    Background: Heat waves have a drastic impact on urban populations, which could increase with climate change. Objectives: We evaluated new indicators of elderly people’s exposure to heat in Paris, from a public health prevention perspective, using satellite thermal images. Methods: We used a time series of 61 images from the satellites of the National Oceanic and Atmospheric Administration’s (NOAA) Advanced Very High Resolution Radiometer (AVHRR) taken from 1 to 13 August 2003 to produce thermal indicators of minimum, maximum, and mean surface temperatures and diurnal temperature amplitude, with different lags between the meteorological data and the health impact. Health data came from a case–control study involving 241 people ≥ 65 years of age who died in the city of Paris or the nearby suburban area of Val-de-Marne during the August 2003 heat wave, and 241 controls who were matched to cases on age, sex, and residential zone. For each person, we integrated the thermal indicators in a conditional logistic regression model, adjusted for age and other potential confounders. We computed odds ratios (ORs) comparing the 90th and 50th percentiles of the temperature differences between cases and controls for various indicators. Results: Mortality risk was significantly associated with exposure for two indicators: minimum temperatures averaged for 1–13 August [for a 0.41°C increase, OR = 2.17; 95% confidence interval (CI): 1.14, 4.16] and minimum temperature averaged on the day of death and the 6 preceding days (for a 0.51°C increase: OR = 2.24; 95% CI: 1.03, 4.87). Conclusions: Our results support the influence of night temperatures on the health impact of heat waves in urban areas. Urban heat exposure indicators based on satellite imagery have the potential to identify areas with higher risk of death, which could inform intervention decisions by key stakeholders. PMID:21885383

  2. Calculation of enhanced slowing and cooling due to the addition of a traveling wave to an intense optical standing wave

    NASA Astrophysics Data System (ADS)

    Gottesman, D.; Mervis, J.; Prentiss, M.; Bigelow, N. P.

    1992-07-01

    We investigate the force on a two-level atom interacting with intense monochromatic laser fields which are combinations of standing and traveling waves. We present a continued-fraction solution to the optical Bloch equations. Using this solution to calculate the force on an atom, we have examined the slowing and cooling of a thermal Na atomic beam. We find that the addition of a traveling wave to an intense standing wave can significantly improve the slowing rate and simultaneously decrease the final velocity of the cooled beam.

  3. Heat Waves and Climate Change: Applying the Health Belief Model to Identify Predictors of Risk Perception and Adaptive Behaviours in Adelaide, Australia

    PubMed Central

    Akompab, Derick A.; Bi, Peng; Williams, Susan; Grant, Janet; Walker, Iain A.; Augoustinos, Martha

    2013-01-01

    Heat waves are considered a health risk and they are likely to increase in frequency, intensity and duration as a consequence of climate change. The effects of heat waves on human health could be reduced if individuals recognise the risks and adopt healthy behaviours during a heat wave. The purpose of this study was to determine the predictors of risk perception using a heat wave scenario and identify the constructs of the health belief model that could predict adaptive behaviours during a heat wave. A cross-sectional study was conducted during the summer of 2012 among a sample of persons aged between 30 to 69 years in Adelaide. Participants’ perceptions were assessed using the health belief model as a conceptual frame. Their knowledge about heat waves and adaptive behaviours during heat waves was also assessed. Logistic regression analyses were performed to determine the predictors of risk perception to a heat wave scenario and adaptive behaviours during a heat wave. Of the 267 participants, about half (50.9%) had a high risk perception to heat waves while 82.8% had good adaptive behaviours during a heat wave. Multivariate models found that age was a significant predictor of risk perception. In addition, participants who were married (OR = 0.21; 95% CI, 0.07–0.62), who earned a gross annual household income of ≥$60,000 (OR = 0.41; 95% CI, 0.17–0.94) and without a fan (OR = 0.29; 95% CI, 0.11–0.79) were less likely to have a high risk perception to heat waves. Those who were living with others (OR = 2.87; 95% CI, 1.19–6.90) were more likely to have a high risk perception to heat waves. On the other hand, participants with a high perceived benefit (OR = 2.14; 95% CI, 1.00–4.58), a high “cues to action” (OR = 3.71; 95% CI, 1.63–8.43), who had additional training or education after high school (OR = 2.65; 95% CI, 1.25–5.58) and who earned a gross annual household income of ≥$60,000 (OR = 2.66; 95% CI, 1.07–6.56) were more likely to have good

  4. A propagating heat wave model of skin electroporation.

    PubMed

    Pliquett, Uwe; Gusbeth, Ch; Nuccitelli, Richard

    2008-03-21

    The main barrier to transdermal drug delivery in human skin is the stratum corneum. Pulsed electric fields (PEFs) of sufficient amplitude can create new aqueous pathways across this barrier and enhance drug delivery through the skin. Here, we describe a model of pore formation between adjacent corneocytes that predicts the following sequence of events: (1) the PEF rapidly charges the stratum corneum near the electrode until the transepidermal potential difference is large enough to drive water into a small region of the stratum corneum, creating new aqueous pathways. (2) PEFs then drive a high current density through this newly created electropore to generate Joule heating that warms the pore perimeter. (3) This temperature rise at the perimeter increases the probability of further electroporation there as the local sphingolipids reach their phase transition temperature. (4) This heat-generated wave of further electroporation propagates outward until the surface area of the pore becomes so large that the reduced current density no longer generates sufficient heat to reach the phase transition temperature of the sphingolipids. (5) Cooling and partial recovery occurs after the field pulse. This process yields large, high permeability regions in the stratum corneum at which molecules can more readily cross this skin barrier. We present a model for this process that predicts that the initial radius of the first aqueous pathway is approximately 5nm for a transdermal voltage of 60V at room temperature.

  5. 40 CFR 97.76 - Additional requirements to provide heat input data.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... heat input data. 97.76 Section 97.76 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Monitoring and Reporting § 97.76 Additional requirements to provide heat input data. The owner or operator of... a flow system shall also monitor and report heat input rate at the unit level using the...

  6. 40 CFR 97.76 - Additional requirements to provide heat input data.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... heat input data. 97.76 Section 97.76 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Monitoring and Reporting § 97.76 Additional requirements to provide heat input data. The owner or operator of... a flow system shall also monitor and report heat input rate at the unit level using the...

  7. 40 CFR 97.76 - Additional requirements to provide heat input data.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... heat input data. 97.76 Section 97.76 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Monitoring and Reporting § 97.76 Additional requirements to provide heat input data. The owner or operator of... a flow system shall also monitor and report heat input rate at the unit level using the...

  8. 40 CFR 97.76 - Additional requirements to provide heat input data.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... heat input data. 97.76 Section 97.76 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Monitoring and Reporting § 97.76 Additional requirements to provide heat input data. The owner or operator of... a flow system shall also monitor and report heat input rate at the unit level using the...

  9. 40 CFR 60.4176 - Additional requirements to provide heat input data.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 6 2011-07-01 2011-07-01 false Additional requirements to provide heat... requirements to provide heat input data. The owner or operator of a Hg Budget unit that monitors and reports Hg... monitor and report heat input rate at the unit level using the procedures set forth in part 75 of...

  10. 40 CFR 97.76 - Additional requirements to provide heat input data.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... heat input data. 97.76 Section 97.76 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Monitoring and Reporting § 97.76 Additional requirements to provide heat input data. The owner or operator of... a flow system shall also monitor and report heat input rate at the unit level using the...

  11. 40 CFR 60.4176 - Additional requirements to provide heat input data.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Additional requirements to provide heat... requirements to provide heat input data. The owner or operator of a Hg Budget unit that monitors and reports Hg... monitor and report heat input rate at the unit level using the procedures set forth in part 75 of...

  12. The impact of heat, cold, and heat waves on hospital admissions in eight cities in Korea

    NASA Astrophysics Data System (ADS)

    Son, Ji-Young; Bell, Michelle L.; Lee, Jong-Tae

    2014-01-01

    Although the impact of temperature on mortality is well documented, relatively fewer studies have evaluated the associations of temperature with morbidity outcomes such as hospital admissions, and most studies were conducted in North America or Europe. We evaluated weather and hospital admissions including specific causes (allergic disease, asthma, selected respiratory disease, and cardiovascular disease) in eight major cities in Korea from 2003 to 2008. We also explored potential effect modification by individual characteristics such as sex and age. We used hierarchical modeling to first estimate city-specific associations between heat, cold, or heat waves and hospitalizations, and then estimated overall effects. Stratified analyses were performed by cause of hospitalization, sex, and age (0-14, 15-64, 65-74, and ≥75 years). Cardiovascular hospitalizations were significantly associated with high temperature, whereas hospitalizations for allergic disease, asthma, and selected respiratory disease were significantly associated with low temperature. The overall heat effect for cardiovascular hospitalization was a 4.5 % (95 % confidence interval 0.7, 8.5 %) increase in risk comparing hospitalizations at 25 to 15 °C. For cold effect, the overall increase in risk of hospitalizations comparing 2 with 15 °C was 50.5 (13.7, 99.2 %), 43.6 (8.9, 89.5 %), and 53.6 % (9.8, 114.9 %) for allergic disease, asthma, and selected respiratory disease, respectively. We did not find statistically significant effects of heat waves compared with nonheat wave days. Our results suggest susceptible populations such as women and younger persons. Our findings provide suggestive evidence that both high and low ambient temperatures are associated with the risk of hospital admissions, particularly in women or younger person, in Korea.

  13. X-ray analysis of electron Bernstein wave heating in MST

    NASA Astrophysics Data System (ADS)

    Seltzman, A. H.; Anderson, J. K.; DuBois, A. M.; Almagri, A.; Forest, C. B.

    2016-11-01

    A pulse height analyzing x-ray tomography system has been developed to detect x-rays from electron Bernstein wave heated electrons in the Madison symmetric torus reversed field pinch (RFP). Cadmium zinc telluride detectors are arranged in a parallel beam array with two orthogonal multi-chord detectors that may be used for tomography. In addition a repositionable 16 channel fan beam camera with a 55° field of view is used to augment data collected with the Hard X-ray array. The chord integrated signals identify target emission from RF heated electrons striking a limiter located 12° toroidally away from the RF injection port. This provides information on heated electron spectrum, transport, and diffusion. RF induced x-ray emission from absorption on harmonic electron cyclotron resonances in low current (<250 kA) RFP discharges has been observed.

  14. Heat waves and morbidity: current knowledge and further direction-a comprehensive literature review.

    PubMed

    Li, Mengmeng; Gu, Shaohua; Bi, Peng; Yang, Jun; Liu, Qiyong

    2015-05-18

    In the past few decades, several devastating heat wave events have significantly challenged public health. As these events are projected to increase in both severity and frequency in the future, it is important to assess the relationship between heat waves and the health indicators that can be used in the early warning systems to guide the public health response. Yet there is a knowledge gap in the impact of heat waves on morbidity. In this study, a comprehensive review was conducted to assess the relationship between heat waves and different morbidity indicators, and to identify the vulnerable populations. The PubMed and ScienceDirect database were used to retrieve published literature in English from 1985 to 2014 on the relationship between heat waves and morbidity, and the following MeSH terms and keywords were used: heat wave, heat wave, morbidity, hospital admission, hospitalization, emergency call, emergency medical services, and outpatient visit. Thirty-three studies were included in the final analysis. Most studies found a short-term negative health impact of heat waves on morbidity. The elderly, children, and males were more vulnerable during heat waves, and the medical care demand increased for those with existing chronic diseases. Some social factors, such as lower socioeconomic status, can contribute to heat-susceptibility. In terms of study methods and heat wave definitions, there remain inconsistencies and uncertainties. Relevant policies and guidelines need to be developed to protect vulnerable populations. Morbidity indicators should be adopted in heat wave early warning systems in order to guide the effective implementation of public health actions.

  15. Heat Waves and Morbidity: Current Knowledge and Further Direction-A Comprehensive Literature Review

    PubMed Central

    Li, Mengmeng; Gu, Shaohua; Bi, Peng; Yang, Jun; Liu, Qiyong

    2015-01-01

    In the past few decades, several devastating heat wave events have significantly challenged public health. As these events are projected to increase in both severity and frequency in the future, it is important to assess the relationship between heat waves and the health indicators that can be used in the early warning systems to guide the public health response. Yet there is a knowledge gap in the impact of heat waves on morbidity. In this study, a comprehensive review was conducted to assess the relationship between heat waves and different morbidity indicators, and to identify the vulnerable populations. The PubMed and ScienceDirect database were used to retrieve published literature in English from 1985 to 2014 on the relationship between heat waves and morbidity, and the following MeSH terms and keywords were used: heat wave, heat wave, morbidity, hospital admission, hospitalization, emergency call, emergency medical services, and outpatient visit. Thirty-three studies were included in the final analysis. Most studies found a short-term negative health impact of heat waves on morbidity. The elderly, children, and males were more vulnerable during heat waves, and the medical care demand increased for those with existing chronic diseases. Some social factors, such as lower socioeconomic status, can contribute to heat-susceptibility. In terms of study methods and heat wave definitions, there remain inconsistencies and uncertainties. Relevant policies and guidelines need to be developed to protect vulnerable populations. Morbidity indicators should be adopted in heat wave early warning systems in order to guide the effective implementation of public health actions. PMID:25993103

  16. Computational exploration of wave propagation and heating from transcranial focused ultrasound for neuromodulation

    NASA Astrophysics Data System (ADS)

    Mueller, Jerel K.; Ai, Leo; Bansal, Priya; Legon, Wynn

    2016-10-01

    Objective. While ultrasound is largely established for use in diagnostic imaging, its application for neuromodulation is relatively new and crudely understood. The objective of the present study was to investigate the effects of tissue properties and geometry on the wave propagation and heating in the context of transcranial neuromodulation. Approach. A computational model of transcranial-focused ultrasound was constructed and validated against empirical data. The models were then incrementally extended to investigate a number of issues related to the use of ultrasound for neuromodulation, including the effect on wave propagation of variations in geometry of skull and gyral anatomy as well as the effect of multiple tissue and media layers, including scalp, skull, CSF, and gray/white matter. In addition, a sensitivity analysis was run to characterize the influence of acoustic properties of intracranial tissues. Finally, the heating associated with ultrasonic stimulation waveforms designed for neuromodulation was modeled. Main results. The wave propagation of a transcranially focused ultrasound beam is significantly influenced by the cranial domain. The half maximum acoustic beam intensity profiles are insensitive overall to small changes in material properties, though the inclusion of sulci in models results in greater peak intensity values compared to a model without sulci (1%–30% greater). Finally, heating using currently employed stimulation parameters in humans is highest in bone (0.16 °C) and is negligible in brain (4.27 × 10–3 °C) for a 0.5 s exposure. Significance. Ultrasound for noninvasive neuromodulation holds great promise and appeal for its non-invasiveness, high spatial resolution and deep focal lengths. Here we show gross brain anatomy and biological material properties to have limited effect on ultrasound wave propagation and to result in safe heating levels in the skull and brain.

  17. Computational exploration of wave propagation and heating from transcranial focused ultrasound for neuromodulation

    NASA Astrophysics Data System (ADS)

    Mueller, Jerel K.; Ai, Leo; Bansal, Priya; Legon, Wynn

    2016-10-01

    Objective. While ultrasound is largely established for use in diagnostic imaging, its application for neuromodulation is relatively new and crudely understood. The objective of the present study was to investigate the effects of tissue properties and geometry on the wave propagation and heating in the context of transcranial neuromodulation. Approach. A computational model of transcranial-focused ultrasound was constructed and validated against empirical data. The models were then incrementally extended to investigate a number of issues related to the use of ultrasound for neuromodulation, including the effect on wave propagation of variations in geometry of skull and gyral anatomy as well as the effect of multiple tissue and media layers, including scalp, skull, CSF, and gray/white matter. In addition, a sensitivity analysis was run to characterize the influence of acoustic properties of intracranial tissues. Finally, the heating associated with ultrasonic stimulation waveforms designed for neuromodulation was modeled. Main results. The wave propagation of a transcranially focused ultrasound beam is significantly influenced by the cranial domain. The half maximum acoustic beam intensity profiles are insensitive overall to small changes in material properties, though the inclusion of sulci in models results in greater peak intensity values compared to a model without sulci (1%-30% greater). Finally, heating using currently employed stimulation parameters in humans is highest in bone (0.16 °C) and is negligible in brain (4.27 × 10-3 °C) for a 0.5 s exposure. Significance. Ultrasound for noninvasive neuromodulation holds great promise and appeal for its non-invasiveness, high spatial resolution and deep focal lengths. Here we show gross brain anatomy and biological material properties to have limited effect on ultrasound wave propagation and to result in safe heating levels in the skull and brain.

  18. Ion-ion waves in the auroral region - Wave excitation and ion heating

    NASA Technical Reports Server (NTRS)

    Dusenbery, P. B.; Martin, R. F., Jr.; Winglee, R. M.

    1988-01-01

    The properties of the ion-ion mode which is excited in plasmas when two or more cold ion beams are streaming relative to one another are investigated assuming a warm electron distribution at rest (the model consistent with particle distributions observed in auroral plasma cavities). Numerical solutions are derived for the generalized electrostatic dispersion equation for parallel propagation and for oblique propagation of ion waves. It is shown that the relative ion temperature and concentration have significant effects on the stability of the accelerated plasma and the expected ion heating. Finally, a relationship between ion drift and thermal speed is derived using the marginal stability of ion-ion waves for nonzero ion temperature; the relationship was found to compare favorably with DE-1 ion observations at the high-altitude boundary of the auroral cavity.

  19. Heat Wave-Associated Vibriosis, Sweden and Finland, 2014.

    PubMed

    Baker-Austin, Craig; Trinanes, Joaquin A; Salmenlinna, Saara; Löfdahl, Margareta; Siitonen, Anja; Taylor, Nick G H; Martinez-Urtaza, Jaime

    2016-07-01

    During summer 2014, a total of 89 Vibrio infections were reported in Sweden and Finland, substantially more yearly infections than previously have been reported in northern Europe. Infections were spread across most coastal counties of Sweden and Finland, but unusually, numerous infections were reported in subarctic regions; cases were reported as far north as 65°N, ≈100 miles (160 km) from the Arctic Circle. Most infections were caused by non-O1/O139 V. cholerae (70 cases, corresponding to 77% of the total, all strains were negative for the cholera toxin gene). An extreme heat wave in northern Scandinavia during summer 2014 led to unprecedented high sea surface temperatures, which appear to have been responsible for the emergence of Vibrio bacteria at these latitudes. The emergence of vibriosis in high-latitude regions requires improved diagnostic detection and clinical awareness of these emerging pathogens. PMID:27314874

  20. Severe summer heat waves over Georgia: trends, patterns and driving forces

    NASA Astrophysics Data System (ADS)

    Keggenhoff, I.; Elizbarashvili, M.; King, L.

    2015-11-01

    During the last 50 years Georgia experienced a rising number of severe summer heat waves causing increasing heat-health impacts. In this study, the 10 most severe heat waves between 1961 and 2010 and recent changes in heat wave characteristics have been detected from 22 homogenized temperature minimum and maximum series using the Excess Heat Factor (EHF). A composite and Canonical Correlation Analysis (CCA) have been performed to study summer heat wave patterns and their relationships to the selected predictors: mean Sea Level Pressure (SLP), Geopotential Height at 500 mb (Z500), Sea Surface Temperature (SST), Zonal (u-wind500) and Meridional Wind at 500 mb (v-wind500), Vertical Velocity at 500 mb (O500), Outgoing Longwave Radiation (OLR), Relative Humidity (RH500), Precipitation (RR) and Soil Moisture (SM). Most severe heat events during the last 50 years are identified in 2007, 2006 and 1998. Largest significant trend magnitudes for the number, intensity and duration of low and high-impact heat waves have been found during the last 30 years. Significant changes in the heat wave predictors reveal that all relevant surface and atmospheric patterns contributing to heat waves have been intensified between 1961 and 2010. Composite anomalies and CCA patterns provide evidence of a large anticyclonic blocking pattern over the southern Ural Mountains, which attracts warm air masses from the Southwest, enhances subsidence and surface heating, shifts the African Intertropical Convergence Zone (ITCZ) northwards, and causes a northward shift of the subtropical jet. Moreover, pronounced precipitation and soil moisture deficiency throughout Georgia contribute to the heat wave formation and persistence over Georgia. Due to different large- to mesoscale circulation patterns and the local terrain, heat wave effects over Eastern Georgia are dominated by subsidence and surface heating, while convective rainfall and cooling are observed in the West.

  1. Impacts and Responses to the 1995 Heat Wave: A Call to Action.

    NASA Astrophysics Data System (ADS)

    Changnon, Stanley A.; Kunkel, Kenneth E.; Reinke, Beth C.

    1996-07-01

    The short but intense heat wave in mid-July 1995 caused 830 deaths nationally, with 525 of these deaths in Chicago. Many of the dead were elderly. and the event raised great concern over why it happened. Assessment of causes for the heat wave-related deaths in Chicago revealed many factors were at fault, including an inadequate local heat wave warning system, power failures, questionable death assessments, inadequate ambulance service and hospital facilities, the heat island, an aging population, and the inability of many persons to properly ventilate their residences due to fear of crime or a lack of resources for fans or air conditioning. Heat-related deaths appear to be on the increase in the United States. Heat-related deaths greatly exceed those caused by other life-threatening weather conditions. Analysis of the impacts and responses to this heat wave reveals a need to 1) define the heat island conditions during heat waves for all major cities is a means to improve forecasts of threatening conditions, 2) develop a nationally uniform means for classifying heat-related deaths, 3) improve warning systems that are designed around local conditions of large cities, and 4) increase research on the meteorological and climatological aspects of heat stress and heat waves.

  2. Climate change induced heat wave hazard in eastern Africa: Dar Es Salaam (Tanzania) and Addis Ababa (Ethiopia) case study

    NASA Astrophysics Data System (ADS)

    Capuano, Paolo; Sellerino, Mariangela; Di Ruocco, Angela; Kombe, Wilbard; Yeshitela, Kumelachew

    2013-04-01

    Last decades, new records were set in the world for tornadoes, drought, wind, floods, wildfires and hot temperatures, testifying unusual weather and climate patterns with increasing frequency and intensity of extreme weather events. Extreme heat events are natural hazards affecting many regions in the world, nevertheless limited work has been done on the analysis and effects of extreme heat events in Africa, that is considered a continent particularly vulnerable to the effects of climate change. In fact, the increase of temperature expected in the African continent during the 21st century is larger than the global mean warming, being about 3° to 4° C, about 1.5 times the global temperature increase (Christensen et al., 2007; Gualdi et al., 2012), with the subtropical regions projected to warm more than the tropical regions. Observations and downscaled model simulations (RCP4.5 and RCP8.5 IPCC scenarios) are analyzed to describe heat wave characteristics in Dar es Salaam (Tanzania) and Addis Ababa (Ethiopia), spanning the last five decades as well as that projected for the 21st century. Observed data are daily maximum and minimum temperature collected in the period 1961-2011; downscaled model simulations span up to 2050. Heat waves are defined following a peak over threshold approach by statistical comparison to historical meteorological baselines (site dependent), using a fixed absolute threshold. Projected future warming in the Dar es Salaam and Addis Ababa shows a further increase in the heat waves parameters. Heat wave duration and hot days number are strictly correlated showing that the temperature rise could generate not only an increase of heat waves number but mainly a longer average duration, that can strongly affect the resilience capacity of the population, particularly the elder people. In fact, the impacts of heat waves on the society are determined also by temporal duration (Stephenson, 2008), in addition to their frequency, in fact the capacity of

  3. Contrasting responses of urban and rural surface energy budgets to heat waves explain synergies between urban heat islands and heat waves

    NASA Astrophysics Data System (ADS)

    Li, Dan; Sun, Ting; Liu, Maofeng; Yang, Long; Wang, Linlin; Gao, Zhiqiu

    2015-05-01

    Heat waves (HWs) are projected to become more frequent and last longer over most land areas in the late 21st century, which raises serious public health concerns. Urban residents face higher health risks due to synergies between HWs and urban heat islands (UHIs) (i.e., UHIs are higher under HW conditions). However, the responses of urban and rural surface energy budgets to HWs are still largely unknown. This study analyzes observations from two flux towers in Beijing, China and reveals significant differences between the responses of urban and rural (cropland) ecosystems to HWs. It is found that UHIs increase significantly during HWs, especially during the nighttime, implying synergies between HWs and UHIs. Results indicate that the urban site receives more incoming shortwave radiation and longwave radiation due to HWs as compared to the rural site, resulting in a larger radiative energy input into the urban surface energy budget. Changes in turbulent heat fluxes also diverge strongly for the urban site and the rural site: latent heat fluxes increase more significantly at the rural site due to abundant available water, while sensible heat fluxes and possibly heat storage increase more at the urban site. These comparisons suggest that the contrasting responses of urban and rural surface energy budgets to HWs are responsible for the synergies between HWs and UHIs. As a result, urban mitigation and adaption strategies such as the use of green roofs and white roofs are needed in order to mitigate the impact of these synergies.

  4. Hot bats: extreme thermal tolerance in a desert heat wave.

    PubMed

    Bondarenco, Artiom; Körtner, Gerhard; Geiser, Fritz

    2014-08-01

    Climate change is predicted to increase temperature extremes and thus thermal stress on organisms. Animals living in hot deserts are already exposed to high ambient temperatures (T a) making them especially vulnerable to further warming. However, little is known about the effect of extreme heat events on small desert mammals, especially tree-roosting microbats that are not strongly protected from environmental temperature fluctuations. During a heat wave with record T as at Sturt National Park, we quantified the thermal physiology and behaviour of a single free-ranging little broad-nosed (Scotorepens greyii, henceforth Scotorepens) and two inland freetail bats (Mormopterus species 3, henceforth Mormopterus) using temperature telemetry over 3 days. On 11 and 13 January, maximum T a was ∼45.0 °C, and all monitored bats were thermoconforming. On 12 January 2013, when T a exceeded 48.0 °C, Scotorepens abandoned its poorly insulated roost during the daytime, whereas both Mormopterus remained in their better insulated roosts and were mostly thermoconforming. Maximum skin temperatures (T skin) ranged from 44.0 to 44.3 °C in Scotorepens and from 40.0 to 45.8 °C in Mormopterus, and these are the highest T skin values reported for any free-ranging bat. Our study provides the first evidence of extensive heat tolerance in free-ranging desert microbats. It shows that these bats can tolerate the most extreme T skin range known for mammals (3.3 to 45.8 °C) and delay regulation of T skin by thermoconforming over a wide temperature range and thus decrease the risks of dehydration and consequently death.

  5. Hot bats: extreme thermal tolerance in a desert heat wave

    NASA Astrophysics Data System (ADS)

    Bondarenco, Artiom; Körtner, Gerhard; Geiser, Fritz

    2014-08-01

    Climate change is predicted to increase temperature extremes and thus thermal stress on organisms. Animals living in hot deserts are already exposed to high ambient temperatures ( T a) making them especially vulnerable to further warming. However, little is known about the effect of extreme heat events on small desert mammals, especially tree-roosting microbats that are not strongly protected from environmental temperature fluctuations. During a heat wave with record T as at Sturt National Park, we quantified the thermal physiology and behaviour of a single free-ranging little broad-nosed ( Scotorepens greyii, henceforth Scotorepens) and two inland freetail bats ( Mormopterus species 3, henceforth Mormopterus) using temperature telemetry over 3 days. On 11 and 13 January, maximum T a was ˜45.0 °C, and all monitored bats were thermoconforming. On 12 January 2013, when T a exceeded 48.0 °C, Scotorepens abandoned its poorly insulated roost during the daytime, whereas both Mormopterus remained in their better insulated roosts and were mostly thermoconforming. Maximum skin temperatures ( T skin) ranged from 44.0 to 44.3 °C in Scotorepens and from 40.0 to 45.8 °C in Mormopterus, and these are the highest T skin values reported for any free-ranging bat. Our study provides the first evidence of extensive heat tolerance in free-ranging desert microbats. It shows that these bats can tolerate the most extreme T skin range known for mammals (3.3 to 45.8 °C) and delay regulation of T skin by thermoconforming over a wide temperature range and thus decrease the risks of dehydration and consequently death.

  6. Hot bats: extreme thermal tolerance in a desert heat wave.

    PubMed

    Bondarenco, Artiom; Körtner, Gerhard; Geiser, Fritz

    2014-08-01

    Climate change is predicted to increase temperature extremes and thus thermal stress on organisms. Animals living in hot deserts are already exposed to high ambient temperatures (T a) making them especially vulnerable to further warming. However, little is known about the effect of extreme heat events on small desert mammals, especially tree-roosting microbats that are not strongly protected from environmental temperature fluctuations. During a heat wave with record T as at Sturt National Park, we quantified the thermal physiology and behaviour of a single free-ranging little broad-nosed (Scotorepens greyii, henceforth Scotorepens) and two inland freetail bats (Mormopterus species 3, henceforth Mormopterus) using temperature telemetry over 3 days. On 11 and 13 January, maximum T a was ∼45.0 °C, and all monitored bats were thermoconforming. On 12 January 2013, when T a exceeded 48.0 °C, Scotorepens abandoned its poorly insulated roost during the daytime, whereas both Mormopterus remained in their better insulated roosts and were mostly thermoconforming. Maximum skin temperatures (T skin) ranged from 44.0 to 44.3 °C in Scotorepens and from 40.0 to 45.8 °C in Mormopterus, and these are the highest T skin values reported for any free-ranging bat. Our study provides the first evidence of extensive heat tolerance in free-ranging desert microbats. It shows that these bats can tolerate the most extreme T skin range known for mammals (3.3 to 45.8 °C) and delay regulation of T skin by thermoconforming over a wide temperature range and thus decrease the risks of dehydration and consequently death. PMID:25005222

  7. On the effect of BUM generation enhancement revealed using the scheme of additional heating of ionospheric plasma

    NASA Astrophysics Data System (ADS)

    Frolov, V. L.; Erukhimov, L. M.; Komrakov, G. P.; Sergeev, E. N.; Thidé, B.; Bernhardt, P. A.; Wagner, L. S.; Goldstein, J. A.; Selcher, G.

    1997-05-01

    We present measured characteristics of the artificial ionospheric radio emission (AIRE), which were obtained experimentally using additional heating of the ionospheric F-region by O-polarized waves. It is shown that the observed enhancement of intensity of the broad upshifted maximum (BUM) of the AIRE can result from the influence of electrons accelerated in the plasma: esonance region on its generation. An empirical model of the phenomenon observed is developed. It is concluded from experimental results that the BUM has a complex structure and only one of its components produces the above emission enhancement. We show the possibility of using the AIRE in additional heating of ionospheric plasma for diagnostics of artificial ionospheric turbulence and investigation of the features of perturbation propagation along the geomagnetic field lines.

  8. Recent severe heat waves: how to view them in a 'global warming' perspective?

    NASA Astrophysics Data System (ADS)

    Kysely, J.

    2010-03-01

    The area of western and central Europe has recently been affected by several long-lasting and severe heat waves, particularly in July-August 2003, June-July 2006, and July 2007. The heat waves influenced various sectors of human activities, with enormous socio-economic impacts. With an estimated death toll exceeding 50000 over Europe, the August 2003 heat wave was the worst natural disaster in Europe during the last 50 years, yielding an example of how seriously may also high-income countries be affected by climate change. The aims of the study are to assess whether recent occurrences of severe heat waves in central Europe were exceptional in the context of past fluctuations, and to estimate their recurrence probabilities under future climate change scenarios. We focus on analogs of the 2006 heat wave which lasted 33 consecutive days in Prague and was the longest and most severe heat wave since the beginning of air temperature measurements in 1775. Probabilities of long and severe heat waves are estimated from daily temperature series generated by a first-order autoregressive model with a deterministic component, incorporating the seasonal cycle and the long-term trend. The model is validated with respect to the simulation of heat waves in present climate (1961-2006) and subsequently run under several assumptions reflecting various rates of summer warming over the 21st century, based on climate model projections. The return period of a heat wave reaching or exceeding the length of the 2006 heat wave is estimated to be around 120 years in 2006. Due to an increase in mean summer temperatures, probabilities of very long heat waves have already risen by an order of magnitude over the recent 25 years, and they are likely to increase by another order of magnitude by around 2040 under the summer warming rate assumed by the mid-scenario. Even the lower-bound scenario yields a considerable decline of return periods associated with intense heat waves. Although positive socio

  9. Urban warming in the 2013 summer heat wave in eastern China

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Yan, Zhongwei; Quan, Xiao-Wei; Feng, Jinming

    2016-06-01

    The impact of urban warming during the 2013 July-August extreme heat wave event across the Yangtze River Delta (YRD) in China was assessed. Using a newly developed high-resolution, land-use dataset, urban stations were identified from a total of 101 stations in the YRD. The difference between urban and non-urban/rural stations indicates that urban warming reached 1.22 °C in the 2013 summer heat wave. The new land-use dataset was then input to the Weather Research and Forecasting model to further understand the dynamical/physical processes of the urban warming during the heat wave. The model-simulated urban warming is ~1.5 °C. Impacts of urbanization on near-surface temperature had strong diurnal variation, reaching a peak at 19:00 LST, around sunset. In the daytime, urban warming was mainly caused by enhanced sensible heat fluxes and longwave radiation from the surface. Because of reduced latent heat flux and increased heat capacity, urban ground stored much more heat than rural ground during the daytime, which is later released as sensible heat flux from the surface at night, leading to the nocturnal urban warming. The simulation results also suggest a positive feedback between urban warming and heat wave intensity, which makes the heat wave more intense in urban than rural areas and the urban warming during the extreme heat wave stronger than its climatological mean.

  10. Comparing exposure metrics for classifying 'dangerous heat' in heat wave and health warning systems.

    PubMed

    Zhang, Kai; Rood, Richard B; Michailidis, George; Oswald, Evan M; Schwartz, Joel D; Zanobetti, Antonella; Ebi, Kristie L; O'Neill, Marie S

    2012-10-01

    Heat waves have been linked to excess mortality and morbidity, and are projected to increase in frequency and intensity with a warming climate. This study compares exposure metrics to trigger heat wave and health warning systems (HHWS), and introduces a novel multi-level hybrid clustering method to identify potential dangerously hot days. Two-level and three-level hybrid clustering analysis as well as common indices used to trigger HHWS, including spatial synoptic classification (SSC), and the 90th, 95th, and 99th percentiles of minimum and relative minimum temperature (using a 10 day reference period), were calculated using a summertime weather dataset in Detroit from 1976 to 2006. The days classified as 'hot' with hybrid clustering analysis, SSC, minimum and relative minimum temperature methods differed by method type. SSC tended to include the days with, on average, 2.5 °C lower daily minimum temperature and 5.3 °C lower dew point than days identified by other methods. These metrics were evaluated by comparing their performance in predicting excess daily mortality. The 99th percentile of minimum temperature was generally the most predictive, followed by the three-level hybrid clustering method, the 95th percentile of minimum temperature, SSC and others. Our proposed clustering framework has more flexibility and requires less substantial meteorological prior information than the synoptic classification methods. Comparison of these metrics in predicting excess daily mortality suggests that metrics thought to better characterize physiological heat stress by considering several weather conditions simultaneously may not be the same metrics that are better at predicting heat-related mortality, which has significant implications in HHWSs. PMID:22673187

  11. Acidization of a Direct Heat Hydrothermal Well and its Potential in Developing Additional Direct Heat Projects

    SciTech Connect

    Dolenc, M.R.; Strawn, J. A.; Prestwich, S.M.

    1981-01-01

    A matrix acid treatment on a limestone formation in a low temperature hydrothermal production well in South Dakota has resulted in a 40% increase in heat (BTU) available for use in space heating a hospital. The results of this experimental treatment on the Madison Limestone suggest a significant potential may exist for similar applications, particularly throughout the western United States. This paper presents the results of the acid treatment, suggests other possible areas for similar application, and analyzes the economics for successful treatments.

  12. Heat wave hazard classification and risk assessment using artificial intelligence fuzzy logic.

    PubMed

    Keramitsoglou, Iphigenia; Kiranoudis, Chris T; Maiheu, Bino; De Ridder, Koen; Daglis, Ioannis A; Manunta, Paolo; Paganini, Marc

    2013-10-01

    The average summer temperatures as well as the frequency and intensity of hot days and heat waves are expected to increase due to climate change. Motivated by this consequence, we propose a methodology to evaluate the monthly heat wave hazard and risk and its spatial distribution within large cities. A simple urban climate model with assimilated satellite-derived land surface temperature images was used to generate a historic database of urban air temperature fields. Heat wave hazard was then estimated from the analysis of these hourly air temperatures distributed at a 1-km grid over Athens, Greece, by identifying the areas that are more likely to suffer higher temperatures in the case of a heat wave event. Innovation lies in the artificial intelligence fuzzy logic model that was used to classify the heat waves from mild to extreme by taking into consideration their duration, intensity and time of occurrence. The monthly hazard was subsequently estimated as the cumulative effect from the individual heat waves that occurred at each grid cell during a month. Finally, monthly heat wave risk maps were produced integrating geospatial information on the population vulnerability to heat waves calculated from socio-economic variables.

  13. The great 2006 heat wave over California and Nevada: Signal of an increasing trend

    USGS Publications Warehouse

    Gershunov, A.; Cayan, D.R.; Iacobellis, S.F.

    2009-01-01

    Most of the great California-Nevada heat waves can be classified into primarily daytime or nighttime events depending on whether atmospheric conditions are dry or humid. A rash of nighttime-accentuated events in the last decade was punctuated by an unusually intense case in July 2006, which was the largest heat wave on record (1948-2006). Generally, there is a positive trend in heat wave activity over the entire region that is expressed most strongly and clearly in nighttime rather than daytime temperature extremes. This trend in nighttime heat wave activity has intensified markedly since the 1980s and especially since 2000. The two most recent nighttime heat waves were also strongly expressed in extreme daytime temperatures. Circulations associated with great regional heat waves advect hot air into the region. This air can be dry or moist, depending on whether a moisture source is available, causing heat waves to be expressed preferentially during day or night. A remote moisture source centered within a marine region west of Baja California has been increasing in prominence because of gradual sea surface warming and a related increase in atmospheric humidity. Adding to the very strong synoptic dynamics during the 2006 heat wave were a prolonged stream of moisture from this southwestern source and, despite the heightened humidity, an environment in which afternoon convection was suppressed, keeping cloudiness low and daytime temperatures high. The relative contributions of these factors and possible relations to global warming are discussed. ?? 2009 American Meteorological Society.

  14. Stochastic heating of electrons by a large-amplitude extraordinary wave in plasma

    SciTech Connect

    Krasovitskiy, V. B.; Turikov, V. A.

    2010-12-15

    Stochastic heating of plasma electrons by a large-amplitude electromagnetic wave propagating across a strong external magnetic field is studied theoretically and numerically. An analytic estimate of the threshold wave amplitude at which heating begins is obtained. The dependence of the average electron energy on the magnetic field and plasma density is investigated using particle-in-cell simulations.

  15. Enzyme Activity Dynamics in Response to Climate Change: 2011 Drought-Heat Wave

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Extreme weather events such as severe droughts and heat waves may have permanent consequences on soil quality and functioning in agroecosystems. The Southern High Plains (SHP) region of Texas, U.S., a large cotton producing area, experienced a historically extreme drought and heat wave during 2011,...

  16. Risk factors for deaths during the 2009 heat wave in Adelaide, Australia: a matched case-control study

    NASA Astrophysics Data System (ADS)

    Zhang, Ying; Nitschke, Monika; Krackowizer, Antoinette; Dear, Keith; Pisaniello, Dino; Weinstein, Philip; Tucker, Graeme; Shakib, Sepehr; Bi, Peng

    2016-05-01

    The extreme heat wave in Australia in 2009 resulted in significantly increased number of daily deaths. The circumstances that lead to deaths during extreme heat have not been explored before in Australia. This study aims to identify the individual and community risk factors for deaths during this extreme heat wave in Adelaide. A matched case-control study was conducted. Cases were those who died in the Adelaide metropolitan area during the heat wave period. For each case, two community controls were randomly selected, matched by age and gender. Face-to-face or telephone interviews were conducted to collect data of demographic information, living environment, social support, health status and behavioural changes during the heat wave. Descriptive analysis, as well as simple and multiple conditional logistic regressions were performed. In total, 82 deaths and 164 matched community controls were included in the analysis, with a median age of 77.5 (range 26.6-100.7). The multiple logistic regression model indicated that, compared with controls, the risk of death during the heat wave was significantly increased for people living alone (AOR = 42.31, 95 % CI 2.3, 792.8) or having existing chronic heart disease (AOR = 22.4, 95 % CI 1.7, 303.0). In addition, having air conditioning in bedrooms (AOR = 0.004, 95 % CI 0.00006, 0.28) and participating in social activities more than once a week (AOR = 0.011, 95 % CI 0.0004, 0.29) indicated significant protective effects. We have identified factors that could significantly impact on the likelihood of deaths during heat waves. Our findings could assist in the development of future intervention programs and policies to reduce mortality associated with a warmer climate.

  17. The role of Alfvén wave heating in solar prominences

    NASA Astrophysics Data System (ADS)

    Soler, Roberto; Terradas, Jaume; Oliver, Ramon; Ballester, Jose Luis

    2016-07-01

    Observations have shown that magnetohydrodynamic waves over a large frequency range are ubiquitous in solar prominences. The waves are probably driven by photospheric motions and may transport energy up to prominences suspended in the corona. Dissipation of wave energy can lead to heating of the cool prominence plasma, thereby contributing to the local energy balance within the prominence. Here we discuss the role of Alfvén wave dissipation as a heating mechanism for the prominence plasma. We consider a slab-like quiescent prominence model with a transverse magnetic field embedded in the solar corona. The prominence medium is modeled as a partially ionized plasma composed of a charged ion-electron single fluid and two separate neutral fluids corresponding to neutral hydrogen and neutral helium. Friction between the three fluids acts as a dissipative mechanism for the waves. The heating caused by Alfvén waves incident on the prominence slab is analytically explored. We find that the dense prominence slab acts as a resonant cavity for the waves. The fraction of incident wave energy that is channeled into the slab strongly depends upon the wave period, P. Using typical prominence conditions, we obtain that wave energy trapping and associated heating are negligible when P ≳ 100 s, so that it is unlikely that those waves have a relevant influence on prominence energetics. When 1 s ≲ P ≲ 100 s the energy absorption into the slab shows several sharp and narrow peaks that can reach up to ~100% when the incident wave frequency matches a cavity resonance of the slab. Wave heating is enhanced at those resonant frequencies. Conversely, when P ≲ 1 s cavity resonances are absent, but the waves are heavily damped by the strong dissipation. We estimate that wave heating may compensate for about 10% of radiative losses of the prominence plasma.

  18. Decreased impacts of the 2003 heat waves on mortality in the Czech Republic: an improved response?

    NASA Astrophysics Data System (ADS)

    Kyselý, Jan; Kříž, Bohumír

    2008-11-01

    The paper examines impacts on mortality of heat waves in 2003, the hottest summer on record in the Czech Republic, and compares them with previous similar events. While most summer heat waves over the period since 1986 were associated with significantly elevated mortality, this was not the case for three out of the four heat waves in 2003. The relatively weak mortality response was particularly noteworthy for the most severe heat wave which occurred in the first 10 days of August 2003 and resulted in enormous excess mortality in some western European countries. A mortality displacement effect and short-term adaptation to heat contributed to the reduced mortality impacts of the heat waves that followed after previous relatively warm periods. However, the decreased mortality response of the 2003 heat waves compared to previous heat waves in the 1990s is also likely to have arisen from positive health-care and other socio-economic changes in the post-communist central European region over the past decade, as well as a better public awareness of heat-related risks due to enhanced media coverage and regular biometeorological forecast and warnings.

  19. Temporal Changes in Extreme High Temerature, Heat Waves in Istanbul Between 1960-2014

    NASA Astrophysics Data System (ADS)

    Yürük, C.; Ünal, Y. S.; Bilgen, S. I.; Menteş, Ş. S.; İncecik, S.

    2015-12-01

    Climate change has crucial effects on cities and especially for informal settlements, urban poor and other vulnerable groups by influencing human health, assets and livelihoods. These impacts directly result from the variations in temperature and precipitation, and emergence of heat waves, droughts, floods and fires (IPCC, 2014). Summertime episodes with extremely high air temperatures which last for several days or longer are addressed to as heat waves and affect the weather and climate in the globe. The aim of this study is to analyze the occurrence of heat waves in terms of quantity, duration and frequency and also to evaluate the accuracy of the COSMO-CLM (CCLM) model in reproducing the characteristics of heat waves in Istanbul. The summer maximum temperatures of six Turkish State Meteorological Service (TSMS) stations are selected between 1960 and 2014 to estimate the characteristics of heat waves in Istanbul. We define the heat wave if the maximum temperatures exceed a threshold value for at least three consecutive days. The threshold value is determined as 30.5 from the 90th percentile of all six station's observations. Then it is used in the detection of the hot days, heat waves and their durations. The results show that not only the number of heat waves but also duration of heat waves increase towards the end of the study period. Especially, a significant increase in heat wave events is evident after 1990s. In 2012, the number of hot days reaches the maximum value in all stations and Kartal station located southern part of city, has the highest value of 60 hot days. Furthermore, Kartal as an urban area in the Asian side of the city, exhibits highest heat wave duration with 18 consecutive days in 1998. To estimate the relationship between urban heat island intensity and the heat waves, we examined data at 43 stations collected by Disaster Coordination Center and TSMS between 2007 and 2012. Urban heat island phenomenon is found to be related to higher

  20. When will unusual heat waves become normal in a warming Africa?

    NASA Astrophysics Data System (ADS)

    Russo, Simone; Marchese, Andrea F.; Sillmann, J.; Immé, Giuseppina

    2016-05-01

    Africa is one of the most vulnerable continents to climate change. In the upcoming decades the occurrence of longer, hotter and more frequent heat waves could have a strong impact on human mortality and crop production. Here, by applying the heat wave magnitude index daily to temperature reanalysis data, we quantify the magnitude and the spatial extent of the most extreme heat waves experienced in Africa between 1979 and October 2015 across different seasons. Results show that in the recent years Africa experienced hotter, longer and more extent heat waves than in the last two decades of the 20th century. In the future, 50% of regional climateprojections suggest that heat waves that are unusual under present climate conditions will occur on a regular basis by 2040 under the most severe IPCC AR5 scenario (i.e. RCP8.5).

  1. Generation of whistler-wave heated discharges with planar resonant RF networks.

    PubMed

    Guittienne, Ph; Howling, A A; Hollenstein, Ch

    2013-09-20

    Magnetized plasma discharges generated by a planar resonant rf network are investigated. A regime transition is observed above a magnetic field threshold, associated with rf waves propagating in the plasma and which present the characteristics of whistler waves. These wave heated regimes can be considered as analogous to conventional helicon discharges, but in planar geometry.

  2. Characterization of Heat-Wave Propagation through Laser-Driven Ti-Doped Underdense Plasma

    SciTech Connect

    Tanabe, M; Nishimura, H; Ohnishi, N; Fournier, K B; Fujioka, S; Iwamae, A; Hansen, S B; Nagai, K; Girard, F; Primout, M; Villette, B; Brebion, D; Mima, K

    2009-02-23

    The propagation of a laser-driven heat-wave into a Ti-doped aerogel target was investigated. The temporal evolution of the electron temperature was derived by means of Ti K-shell x-ray spectroscopy, and compared with two-dimensional radiation hydrodynamic simulations. Reasonable agreement was obtained in the early stage of the heat-wave propagation. In the later phase, laser absorption, the propagation of the heat wave, and hydrodynamic motion interact in a complex manner, and the plasma is mostly re-heated by collision and stagnation at the target central axis.

  3. Generation of shear Alfvén waves by repetitive electron heating

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Gekelman, W.; Pribyl, P.; Van Compernolle, B.; Papadopoulos, K.

    2016-01-01

    ELF/ULF waves are powerful tools for submarine communication, geophysical mapping, and radiation belt remediation. However, due to their large wavelength (on the order of 102-104 km or 0.1-10 RE) it is difficult to launch them using ground-based antennas. Alternatively, these waves can be generated by modulating the temperature of the ionosphere using ground-based HF transmitters. The paper reports a detailed laboratory study on the generation of shear Alfvén waves by repetitive electron heating. The experiments were conducted on the large plasma device at University of California, Los Angeles. In the experiment, 10 pulses of high-power microwaves (250 kW, 1 µs each) near the plasma frequency modulated at a variable fraction between 0.1 and 1.0 of fci are launched transverse to the background field. In addition to bulk electron heating the interaction generates a population of fast electrons in the tail of the distribution function. The field-aligned current carried by the fast electrons acts as an antenna that radiates shear Alfvén waves. It is demonstrated that a shear Alfvén wave at a controllable, arbitrary frequency (f < fci) can be coherently driven by the repetitive microwave pulses. The radiation pattern and power dependence of the virtual antenna are also presented. The experiments provide a novel virtual antenna concept relevant to the equatorial region where the Earth's magnetic field is horizontal and the field-aligned plasma density gradient is small. The results are important to design of new mobile ionospheric heaters for equatorial and middle latitude locations.

  4. Effects of Autumn and Spring Heat Waves on Seed Germination of High Mountain Plants.

    PubMed

    Orsenigo, Simone; Abeli, Thomas; Rossi, Graziano; Bonasoni, Paolo; Pasquaretta, Cristian; Gandini, Maurizia; Mondoni, Andrea

    2015-01-01

    Alpine plants are considered to be particularly vulnerable to climate change and related extreme episodes, such as heat waves. Despite growing interest in the impact of heat waves on alpine plants, knowledge about their effects on regeneration is still fragmentary. Recruitment from seeds will be crucial for the successful migration and survival of these species and will play a key role in their future adaptation to climate change. In this study, we assessed the impacts of heat waves on the seed germination of 53 high mountain plants from the Northern Apennines (Italy). The seeds were exposed to laboratory simulations of three seasonal temperature treatments, derived from real data recorded at a meteorological station near the species growing site, which included two heat wave episodes that occurred both in spring 2003 and in autumn 2011. Moreover, to consider the effect of increasing drought conditions related to heat waves, seed germination was also investigated under four different water potentials. In the absence of heat waves, seed germination mainly occurred in spring, after seeds had experienced autumn and winter seasons. However, heat waves resulted in a significant increase of spring germination in c. 30% of the species and elicited autumn germination in 50%. When heat waves were coupled with drought, seed germination decreased in all species, but did not stop completely. Our results suggest that in the future, heat waves will affect the germination phenology of alpine plants, especially conditionally dormant and strictly cold-adapted chorotypes, by shifting the emergence time from spring to autumn and by increasing the proportion of emerged seedlings. The detrimental effects of heat waves on recruitment success is less likely to be due to the inhibition of seed germination per se, but rather due to seedling survival in seasons, and temperature and water conditions that they are not used to experiencing. Changes in the proportion and timing of emergence

  5. Effects of Autumn and Spring Heat Waves on Seed Germination of High Mountain Plants.

    PubMed

    Orsenigo, Simone; Abeli, Thomas; Rossi, Graziano; Bonasoni, Paolo; Pasquaretta, Cristian; Gandini, Maurizia; Mondoni, Andrea

    2015-01-01

    Alpine plants are considered to be particularly vulnerable to climate change and related extreme episodes, such as heat waves. Despite growing interest in the impact of heat waves on alpine plants, knowledge about their effects on regeneration is still fragmentary. Recruitment from seeds will be crucial for the successful migration and survival of these species and will play a key role in their future adaptation to climate change. In this study, we assessed the impacts of heat waves on the seed germination of 53 high mountain plants from the Northern Apennines (Italy). The seeds were exposed to laboratory simulations of three seasonal temperature treatments, derived from real data recorded at a meteorological station near the species growing site, which included two heat wave episodes that occurred both in spring 2003 and in autumn 2011. Moreover, to consider the effect of increasing drought conditions related to heat waves, seed germination was also investigated under four different water potentials. In the absence of heat waves, seed germination mainly occurred in spring, after seeds had experienced autumn and winter seasons. However, heat waves resulted in a significant increase of spring germination in c. 30% of the species and elicited autumn germination in 50%. When heat waves were coupled with drought, seed germination decreased in all species, but did not stop completely. Our results suggest that in the future, heat waves will affect the germination phenology of alpine plants, especially conditionally dormant and strictly cold-adapted chorotypes, by shifting the emergence time from spring to autumn and by increasing the proportion of emerged seedlings. The detrimental effects of heat waves on recruitment success is less likely to be due to the inhibition of seed germination per se, but rather due to seedling survival in seasons, and temperature and water conditions that they are not used to experiencing. Changes in the proportion and timing of emergence

  6. Changes of western European heat wave characteristics projected by the CMIP5 ensemble

    NASA Astrophysics Data System (ADS)

    Schoetter, Robert; Cattiaux, Julien; Douville, Hervé

    2015-09-01

    We investigate heat waves defined as periods of at least 3 consecutive days of extremely high daily maximum temperature affecting at least 30 % of western Europe. This definition has been chosen to select heat waves that might impact western European electricity supply. Even though not all such heat waves threaten it, the definition allows to identify a sufficient number of events, the strongest being potentially harmful. The heat waves are characterised by their duration, spatial extent, intensity and severity. The heat wave characteristics are calculated for historical and future climate based on results of climate model simulations conducted during the 5th Phase of the Coupled Model Intercomparison Project (CMIP5). The uncertainty of future anthropogenic forcing is taken into account by analysing results for the Representative Concentration Pathway scenarios RCP2.6, RCP4.5 and RCP8.5. The historical simulations are evaluated against the EOBS gridded station data. The CMIP5 ensemble median captures well the observed mean heat wave characteristics. However, no model simulates a heat wave as severe as observed during August 2003. Under future climate conditions, the heat waves become more frequent and have higher mean duration, extent and intensity. The ensemble spread is larger than the scenario uncertainty. The shift of the temperature distribution is more important for the increase of the cumulative heat wave severity than the broadening of the temperature distribution. However, the broadening leads to an amplification of the cumulative heat wave severity by a factor of 1.7 for RCP4.5 and 1.5 for RCP8.5.

  7. Effects of Autumn and Spring Heat Waves on Seed Germination of High Mountain Plants

    PubMed Central

    Orsenigo, Simone; Abeli, Thomas; Rossi, Graziano; Bonasoni, Paolo; Pasquaretta, Cristian; Gandini, Maurizia; Mondoni, Andrea

    2015-01-01

    Alpine plants are considered to be particularly vulnerable to climate change and related extreme episodes, such as heat waves. Despite growing interest in the impact of heat waves on alpine plants, knowledge about their effects on regeneration is still fragmentary. Recruitment from seeds will be crucial for the successful migration and survival of these species and will play a key role in their future adaptation to climate change. In this study, we assessed the impacts of heat waves on the seed germination of 53 high mountain plants from the Northern Apennines (Italy). The seeds were exposed to laboratory simulations of three seasonal temperature treatments, derived from real data recorded at a meteorological station near the species growing site, which included two heat wave episodes that occurred both in spring 2003 and in autumn 2011. Moreover, to consider the effect of increasing drought conditions related to heat waves, seed germination was also investigated under four different water potentials. In the absence of heat waves, seed germination mainly occurred in spring, after seeds had experienced autumn and winter seasons. However, heat waves resulted in a significant increase of spring germination in c. 30% of the species and elicited autumn germination in 50%. When heat waves were coupled with drought, seed germination decreased in all species, but did not stop completely. Our results suggest that in the future, heat waves will affect the germination phenology of alpine plants, especially conditionally dormant and strictly cold-adapted chorotypes, by shifting the emergence time from spring to autumn and by increasing the proportion of emerged seedlings. The detrimental effects of heat waves on recruitment success is less likely to be due to the inhibition of seed germination per se, but rather due to seedling survival in seasons, and temperature and water conditions that they are not used to experiencing. Changes in the proportion and timing of emergence

  8. Projections of heat waves with high impact on human health in Europe

    NASA Astrophysics Data System (ADS)

    Amengual, A.; Homar, V.; Romero, R.; Brooks, H. E.; Ramis, C.; Gordaliza, M.; Alonso, S.

    2014-08-01

    Climate change will result in more intense, more frequent and longer lasting heat waves. The most hazardous conditions emerge when extreme daytime temperatures combine with warm night-time temperatures, high humidities and light winds for several consecutive days. Here, we assess present and future heat wave impacts on human health in Europe. Present daily physiologically equivalent temperatures (PET) are derived from the ERA-Interim reanalysis. PET allows to specifically focus on heat-related risks on humans. Regarding projections, a suite of high-resolution regional climate models - run under SRES A1B scenario - has been used. A quantile-quantile adjustment is applied to the daily simulated PET to correct biases in individual model climatologies and a multimodel ensemble strategy is adopted to encompass model errors. Two types of heat waves differently impacting human health - strong and extreme stress - are defined according to specified thresholds of thermal stress and duration. Heat wave number, frequency, duration and amplitude are derived for each type. Results reveal relatively strong correlations between the spatial distribution of strong and extreme heat wave amplitudes and mortality excess for the 2003 European summer. Projections suggest a steady increase and a northward extent of heat wave attributes in Europe. Strong stress heat wave frequencies could increase more than 40 days, lasting over 20 days more by 2075-2094. Amplitudes might augment up to 7 °C per heat wave day. Important increases in extreme stress heat wave attributes are also expected: up to 40 days in frequency, 30 days in duration and 4 °C in amplitude. We believe that with this information at hand policy makers and stakeholders on vulnerable populations to heat stress can respond more effectively to the future challenges imposed by climate warming.

  9. Characterization of Heat Waves in the Sahel and associated mechanisms

    NASA Astrophysics Data System (ADS)

    Oueslati, Boutheina; Pohl, Benjamin; Moron, Vincent; Rome, Sandra

    2016-04-01

    Large efforts are made to investigate the heat waves (HW) in developed countries because of their devastating impacts on society, economy and environment. This interest increased after the intense event over Europe during summer 2003. However, HWs are still understudied over developing countries. This is particularly true in West Africa, and especially in the Sahel, where temperatures recurrently reach critical values, such as during the 2010 HW event. Understanding the Sahelian HWs and associated health risks constitute the main objective of ACASIS, a 4-year project funded by the French Agence Nationale de la Recherche. Our work contributes to this project and aims at characterizing the Sahelian HWs and understanding the mechanisms associated with such extreme events. There is no universal definition of a HW event, since it is highly dependent on the sector (human health, agriculture, transport...) and region of interest. In our case, a HW is defined when the heat index of the day and of the night exceeds the 90th percentile for at least 3 consecutive days (Rome et al. 2016, in preparation). This index combines temperature and relative humidity in order to determine the human-perceived equivalent temperature (definition adapted from Steadman, 1979). Intrinsic properties of Sahelian HW are analyzed from the Global Summary of the Day (GSOD) synoptic observations and ERA-interim reanalyses over 1979-2014 during boreal spring seasons (April-May-June), the warmest period of the year in the Central Sahel. ERA-interim captures well the observed interannual variability and seasonal cycle at the regional scale, as well as the 1979-2014 increasing linear trend of springtime HW occurrences in the Sahel. Reanalyses, however, overestimate the duration, spatial extent of HW, and underestimate their intensity. For both GSOD and ERA-interim, we show that, over the last three decades, Sahelian HWs tend to become more frequent, last longer, cover larger areas and reach higher

  10. Heating of solar and stellar chromospheres and coronae by MHD waves

    NASA Technical Reports Server (NTRS)

    Musielak, Z. E.

    1992-01-01

    The two general classes of models that deal with the required heating of stellar chromospheres and coronae assume that outer stellar atmospheres are heated by hydrodynamic or by magnetohydrodynamic (MHD) waves and that these waves are generated by turbulent motions in the stellar convection zones. This paper considers the types of MHD waves and the source of these waves in stars like sun, the efficiency of the generation of MHD waves, and the manner of propagation and energy dissipation of MHD waves. It is shown that the basic criteria for the validity of any theory of MHD wave heating must account for the mean level of heating observed in stellar chromospheres and coronae, and for the range of radiative losses observed for a given spectral type. It is also required that the MHD wave heating theory accounts for the existence of inhomogeneities in stellar atmospheres. The results obtained indicate that magnetic tube waves might supply enough energy for the chromospheric and coronal heating and might also account for the observed range of variations of stellar radiative losses for a given spectral type.

  11. ULF Wave Electromagnetic Energy Flux into the Ionosphere: Joule Heating Implications

    NASA Astrophysics Data System (ADS)

    Hartinger, M.; Moldwin, M.; Zou, S.; Bonnell, J. W.; Angelopoulos, V.

    2014-12-01

    Ultra Low Frequency (ULF) waves - such as standing Alfven waves - are one mechanism for coupling the inner magnetosphere to the Earth's ionosphere. For example, they transfer energy from the solar wind or ring current into the Earth's ionosphere via Joule heating. In this study, we use NASA Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellite data to investigate the spatial, frequency, and geomagnetic activity dependence of the ULF wave Poynting vector (electromagnetic energy flux) mapped to the ionosphere. We use these measurements to estimate Joule heating rates. We compare these rates to empirical models of Joule heating associated with large scale, static (on ULF wave timescales) current systems, finding that ULF waves usually contribute little to the global, integrated Joule heating rate. However, there are extreme cases when ULF waves make significant contributions to global Joule heating. Finally, we find ULF waves routinely make significant contributions to local Joule heating rates near the noon and midnight local time sectors, where static current systems nominally contribute less to Joule heating; the most important contributions come from lower frequency (<7 mHz) waves.

  12. Synoptic-scale characteristics and atmospheric controls of summer heat waves in China

    NASA Astrophysics Data System (ADS)

    Wang, Weiwen; Zhou, Wen; Li, Xiuzhen; Wang, Xin; Wang, Dongxiao

    2016-05-01

    Summer heat waves with persistent extreme high temperatures have been occurring with increasing frequency in recent decades. These extreme events have disastrous consequences for human health, economies, and ecosystems. In this study, we examine three summers with intense and protracted heat waves: the summers of 2003, 2006, and 2013, with high temperatures located mainly in southeastern, southwestern, and eastern China, respectively. The synoptic-scale characteristics of these heat waves and associated atmospheric circulation anomalies are investigated. In the early heat wave episode of 2003, a heat center was located in the southeast coastal provinces during the first 20 days of July. The maximum southward displacement of the East Asian jet stream (EAJS) induced anticyclonic anomalies to the south, associated with southwestward intensification of the western North Pacific subtropical high (WNPSH), and extreme high temperatures were found only to the south of the Yangtze River. In the later episode, a poleward displacement of the EAJS and an enhanced WNPSH over the midlatitudes of eastern China resulted in a "heat dome" over the region, and the heat wave extended northward to cover a larger area of eastern China. The coupling between the westward-enhanced WNPSH and poleward-displaced EAJS was found in the East China heat wave of 2013 as well. But the area of high temperatures reached far to the north in August 2013, with below-normal temperatures located in a small region of South China. In the 2006 southwestern drought and heat wave, extreme poleward displacement of the EAJS, associated with extraordinary westward extension of the WNSPH, resulted in further blocking of the moisture supply from the southwest monsoon. Large-scale moisture deficiencies, dry conditions, and downslope winds were common features of all investigated heat wave episodes. But in 2006, low-level heat lows associated with a well-mixed layer due to intensive daytime heating and atmospheric

  13. Definition of temperature thresholds: the example of the French heat wave warning system.

    PubMed

    Pascal, Mathilde; Wagner, Vérène; Le Tertre, Alain; Laaidi, Karine; Honoré, Cyrille; Bénichou, Françoise; Beaudeau, Pascal

    2013-01-01

    Heat-related deaths should be somewhat preventable. In France, some prevention measures are activated when minimum and maximum temperatures averaged over three days reach city-specific thresholds. The current thresholds were computed based on a descriptive analysis of past heat waves and on local expert judgement. We tested whether a different method would confirm these thresholds. The study was set in the six cities of Paris, Lyon, Marseille, Nantes, Strasbourg and Limoges between 1973 and 2003. For each city, we estimated the excess in mortality associated with different temperature thresholds, using a generalised additive model, controlling for long-time trends, seasons and days of the week. These models were used to compute the mortality predicted by different percentiles of temperatures. The thresholds were chosen as the percentiles associated with a significant excess mortality. In all cities, there was a good correlation between current thresholds and the thresholds derived from the models, with 0°C to 3°C differences for averaged maximum temperatures. Both set of thresholds were able to anticipate the main periods of excess mortality during the summers of 1973 to 2003. A simple method relying on descriptive analysis and expert judgement is sufficient to define protective temperature thresholds and to prevent heat wave mortality. As temperatures are increasing along with the climate change and adaptation is ongoing, more research is required to understand if and when thresholds should be modified.

  14. Long-term variability of heat waves in Argentina and recurrence probability of the severe 2008 heat wave in Buenos Aires

    NASA Astrophysics Data System (ADS)

    Rusticucci, Matilde; Almeira, Gustavo; Pecho, Jozef; Kysely, Jan

    2013-04-01

    Heat waves are one of the main concerns related to the impacts of climate change because their frequency and severity are projected to increase in all projections of future climate. The objective of this work is to study the long-term variability in the occurrence of heat waves over Argentina. The number of days in heat waves per decade is analysed, considering spells of minimum temperature above the 90th percentile (MinTHW), maximum temperature above the 90th percentile (MaxTHW) and spells of days with both minimum and maximum temperature above the corresponding 90th percentile (EHW) for the October-March period. Decadal values in Buenos Aires experienced increases in all definitions of heat waves, but at other stations, the combination of different trends or decadal variability result in some cases in a decrease of extreme heat waves, as shown in Córdoba (central Argentina) and Las Lomitas (northern Argentina). In the northwestern part of the country, La Quiaca and Tinogasta show a strong change in the last decade, mainly due to the increment in the persistence of extreme MinTHW but also accompanied by increases in MaxTHW. In general, other stations show a clear positive trend in MinTHW and decadal variability in MaxTHW, with the largest EHW cases in the last decade. We also estimate recurrence probability of the longest and most severe heat wave in Buenos Aires (over 1909-2010, according to MaxTHW) that occurred from 3 to 14 November 2008. We use simulations with a stochastic autoregressive model that reproduces structure of the time series of daily maximum temperatures in Buenos Aires for (i) the recent climate and (ii) under several scenarios of possible future climate development based on climate models' projections. It is shown that the recurrence probability of such long and severe heat wave is likely to decline substantially in the near future even under a moderate warming trend.

  15. Excess mortality and morbidity during the July 2006 heat wave in Porto, Portugal.

    PubMed

    Monteiro, Ana; Carvalho, Vânia; Oliveira, Teresa; Sousa, Carlos

    2013-01-01

    The purpose of this study was to understand the effects of the July 2006 heat wave through the use of the heat index, in mortality (all causes) and morbidity (all causes, respiratory and circulatory diseases) in general, and in people over 74 years and by gender, in Porto. In this paper, the Poisson generalized additive regression model was used to estimate the impact of apparent temperature (heat index) and daily mortality and morbidity during the July 2006 heat wave. Daily mortality, morbidity and heat index were correlated with lags of apparent temperature up to 7 days using Pearson correlation. For a 1°C increase in mean apparent temperature we observed a 2.7 % (95 % CI: 1.7-3.6 %) increase in mortality (all cause), a 1.7 % (95 % CI: 0.6-2.9 %) increase in respiratory morbidity, a 2.2 % (95 % CI: 0.4-4.1 %) increase in respiratory morbidity in women, a 5.4 % (95%CI: 1.1-6.6 %) increase in chronic obstructive pulmonary morbidity, and a 7.5 % (95 % CI: 1.3-14.1 %) increase in chronic obstructive pulmonary morbidity in women, for the entire population. For people ≥ 75 years, our results showed a 3.3 % increase (95 % CI: 1.7-5.0 %) in respiratory morbidity, a 2.7 % (95 % CI: 0.4-5.1 %) increase in respiratory morbidity in men, a 3.9 % (95 %CI: 1.6-6.3 %) increase in respiratory morbidity in women, a 7.0 % (95 % CI: 1.1-13.2 %) in chronic obstructive pulmonary disease, and a 9.0 % (95 % CI: 0.3-18.5 %) in chronic obstructive pulmonary disease in women. The use of heat index in a Mediterranean tempered climate enabled the identification of the effects of the July 2006 heat wave in mortality due to all causes and in respiratory morbidity of the general population, as well as in respiratory morbidity of individuals with more than 74 years of age. PMID:22547142

  16. Excess mortality and morbidity during the July 2006 heat wave in Porto, Portugal

    NASA Astrophysics Data System (ADS)

    Monteiro, Ana; Carvalho, Vânia; Oliveira, Teresa; Sousa, Carlos

    2013-01-01

    The purpose of this study was to understand the effects of the July 2006 heat wave through the use of the heat index, in mortality (all causes) and morbidity (all causes, respiratory and circulatory diseases) in general, and in people over 74 years and by gender, in Porto. In this paper, the Poisson generalized additive regression model was used to estimate the impact of apparent temperature (heat index) and daily mortality and morbidity during the July 2006 heat wave. Daily mortality, morbidity and heat index were correlated with lags of apparent temperature up to 7 days using Pearson correlation. For a 1°C increase in mean apparent temperature we observed a 2.7 % (95 % CI: 1.7-3.6 %) increase in mortality (all cause), a 1.7 % (95 % CI: 0.6-2.9 %) increase in respiratory morbidity, a 2.2 % (95 % CI: 0.4-4.1 %) increase in respiratory morbidity in women, a 5.4 % (95%CI: 1.1-6.6 %) increase in chronic obstructive pulmonary morbidity, and a 7.5 % (95 % CI: 1.3-14.1 %) increase in chronic obstructive pulmonary morbidity in women, for the entire population. For people ≥ 75 years, our results showed a 3.3 % increase (95 % CI: 1.7-5.0 %) in respiratory morbidity, a 2.7 % (95 % CI: 0.4-5.1 %) increase in respiratory morbidity in men, a 3.9 % (95 %CI: 1.6-6.3 %) increase in respiratory morbidity in women, a 7.0 % (95 % CI: 1.1-13.2 %) in chronic obstructive pulmonary disease, and a 9.0 % (95 % CI: 0.3-18.5 %) in chronic obstructive pulmonary disease in women. The use of heat index in a Mediterranean tempered climate enabled the identification of the effects of the July 2006 heat wave in mortality due to all causes and in respiratory morbidity of the general population, as well as in respiratory morbidity of individuals with more than 74 years of age.

  17. Indexes to anticipate negative impacts of heat waves in urban Mediterranean environments

    NASA Astrophysics Data System (ADS)

    Monteiro, A. M.; Carvalho, C. V.; Velho, S. V.; Sousa, C. S.

    2012-04-01

    This study intention is to understand what might be the better indexes to anticipate health deterioration during temperature extreme events in a urban Mediterranean environment like Porto. To do this we look to the effects of the July 2006 Heat Wave using the Heat Index on the Mortality (All Causes) and Morbidity (All Causes, Respiratory and Circulatory diseases) in general, and in people over 74 years and by Gender, in Porto. The Poisson Generalized Additive Regression model was used in order to estimate the impact of Apparent Temperature (Heat Index) and Daily Mortality and Morbidity during the July 2006 Heat Wave. Daily Mortality, Morbidity and Heat Index was correlated with lags of Apparent Temperature up to 7 days using Pearson correlation. For a 1°C increase in mean Apparent Temperature we observed a 2.7% (95%CI:1.7-3.6%) increase in Mortality (for All Causes), 1.7% (95%CI:0.6-2.9%) in Respiratory Morbidity, 2,2% (95%CI:0.4-4.1%) in Women Respiratory Morbidity, 5,4% (95%CI:1.1-6.6%) in Chronic Obstructive Pulmonary Morbidity and 7,5% (95%CI:1.3-14.1%) in Women Chronic Obstructive Pulmonary Morbidity, for the entire population. For people ≥ 75 years, our work showed a 3,3% increase (95%CI:1.7-5.0%) in Respiratory Morbidity, 2,7% (95%CI:0.4-5.1%) in Men Respiratory Morbidity, 3,9% (95%CI:1.6-6.3%) in Women Respiratory Morbidity, 7.0% (95%CI:1.1-13.2%) in Chronic Obstructive Pulmonary Disease and 9.0% (95%CI:0.3-18.5%) in Women Chronic Obstructive Pulmonary Disease. We conclude that the use of Heat Index in a Mediterranean Tempered Climate enabled the identification of the effects of the July 2006 Heat Wave in Mortality due to All Causes and in Respiratory Morbidity of the General Population, as well as in Respiratory Morbidity of individuals with more than 74 years of age.

  18. Impact of heat waves on nonaccidental deaths in Jinan, China, and associated risk factors

    NASA Astrophysics Data System (ADS)

    Zhang, Jun; Liu, Shouqin; Han, Jing; Zhou, Lin; Liu, Yueling; Yang, Liu; Zhang, Ji; Zhang, Ying

    2016-09-01

    An ecological study and a case-crossover analysis were conducted to evaluate the impact of heat waves on nonaccidental deaths, and to identify contributing factors of population vulnerability to heat-related deaths in Jinan, China. Daily death data and meteorological data were collected for summer months (June to August) of 2012-2013. Excess mortality was calculated and multivariate linear regression models were used to assess the increased risk of heat waves on deaths. Univariate and multivariate logistic regression models were performed to estimate the odd ratios (ORs) of risk factors and their 95 % confidence intervals (CIs). Overall, heat waves were related to 24.88 % excess deaths of total nonaccidental deaths and 31.33 % excess deaths of circulatory diseases, with an OR of 16.07 (95 % CI 8.80-23.33) for total nonaccidental deaths and 12.46 (95 % CI 7.39-17.53) for deaths of circulatory diseases. The case-crossover analysis indicated that older people were more likely to die during heat waves (OR = 1.233, 95 % CI 1.076-1.413) and more deaths occurred outside a hospital during heat waves (OR = 1.142, 95 % CI 1.006-1.296). In conclusion, heat waves have caused excess deaths and significantly increased the risk of circulatory deaths. The risk factors identified in our study have implications for public health interventions to reduce heat-related mortality during extreme heat events.

  19. Impact of heat waves on nonaccidental deaths in Jinan, China, and associated risk factors.

    PubMed

    Zhang, Jun; Liu, Shouqin; Han, Jing; Zhou, Lin; Liu, Yueling; Yang, Liu; Zhang, Ji; Zhang, Ying

    2016-09-01

    An ecological study and a case-crossover analysis were conducted to evaluate the impact of heat waves on nonaccidental deaths, and to identify contributing factors of population vulnerability to heat-related deaths in Jinan, China. Daily death data and meteorological data were collected for summer months (June to August) of 2012-2013. Excess mortality was calculated and multivariate linear regression models were used to assess the increased risk of heat waves on deaths. Univariate and multivariate logistic regression models were performed to estimate the odd ratios (ORs) of risk factors and their 95 % confidence intervals (CIs). Overall, heat waves were related to 24.88 % excess deaths of total nonaccidental deaths and 31.33 % excess deaths of circulatory diseases, with an OR of 16.07 (95 % CI 8.80-23.33) for total nonaccidental deaths and 12.46 (95 % CI 7.39-17.53) for deaths of circulatory diseases. The case-crossover analysis indicated that older people were more likely to die during heat waves (OR = 1.233, 95 % CI 1.076-1.413) and more deaths occurred outside a hospital during heat waves (OR = 1.142, 95 % CI 1.006-1.296). In conclusion, heat waves have caused excess deaths and significantly increased the risk of circulatory deaths. The risk factors identified in our study have implications for public health interventions to reduce heat-related mortality during extreme heat events.

  20. Joint Heating of Solar Wind Protons by Multi-Wave-Modes via Multi-Resonances

    NASA Astrophysics Data System (ADS)

    He, Jiansen; Wang, Linghua; Tu, Chuanyi; Marsch, Eckart; Chen, Christopher H. K.; Pei, Zhongtian; Zhang, Lei; Salem, Chadi S.; Bale, Stuart D.

    2016-04-01

    How the protons are heated non-adiabatically in the solar wind turbulence is a long-lasting important problem yet to be solved. The simultaneous analysis of the wave modes and proton kinetics may help to unveil part of the puzzle. The bulk parameters of solar wind protons usually behave differently in the fast and slow streams: e.g., weak VS strong density compressibility, distinct large perpendicular temperature VS evident parallel temperature. These differences may be attributed to the different heating processes in these two types of streams, which is the aim of this work. We find there are different wave activities in the fast and slow streams: quasi-parallel ion cyclotron waves and quasi-perpendicular kinetic Alfvén waves for the former, oblique Alfvén waves and quasi-perpendicular counter-propagating slow magnetosonic waves for the latter. The proton kinetics together with the wave activities reveals the different heating processes for protons in fast and slow streams. For the fast solar wind, proton cores seem to be heated perpendicularly by left-hand polarized ion cyclotron waves, proton beams are heated parallel and perpendicularly by right-hand polarized quasi-perpendicular kinetic Alfvén waves. For the slow solar wind, protons seem to be heated parallel and anti-parallel jointly by counter-propagating oblique Alfvén waves and quasi-perpendicular slow magnetosonic waves through respective Landau resonances, resulting in asymmetric bi-directional beams. Therefore, it is suggested that the solar wind protons are heated jointly in both parallel and perpendicular directions by multi-types of wave modes via various types of resonances.

  1. Seasonal predictability of the 2010 Russian heat wave

    NASA Astrophysics Data System (ADS)

    Katsafados, P.; Papadopoulos, A.; Varlas, G.; Papadopoulou, E.; Mavromatidis, E.

    2014-06-01

    The atmospheric blocking over eastern Europe and western Russia that prevailed during July and August of 2010 led to the development of a devastating Russian heat wave. Therefore the question of whether the event was predictable or not is highly important. The principal aim of this study is to examine the predictability of this high-impact atmospheric event on a seasonal timescale. To this end, a set of dynamical seasonal simulations have been carried out using an atmospheric global circulation model (AGCM). The impact of various model initializations on the predictability of this large-scale event and its sensitivity to the initial conditions has been also investigated. The ensemble seasonal simulations are based on a modified version of the lagged-average forecast method using different lead-time initializations of the model. The results indicated that only a few individual members reproduced the main features of the blocking system 3 months ahead. Most members missed the phase space and the propagation of the system, setting limitations in the predictability of the event.

  2. A study of the heat-removal process at the semiconductor-ceramics interface in solar cells by the laser thermal-wave method

    NASA Astrophysics Data System (ADS)

    Glazov, A. L.; Kalinovskii, V. S.; Kontrosh, E. V.; Muratikov, K. L.

    2016-06-01

    The influence of the solder layer between a semiconductor solar cell and heat-removing ceramics on the nonstationary heat-transfer processes has been investigated by the laser thermal-wave method. A theoretical model taking into account the presence of additional thermal resistance and thermal capacitance at the soldered junction is proposed. Different soldering modes are considered. It is shown that the laser thermal- wave methods within the developed model allow one to correctly estimate the thermophysical properties of multilayer structures.

  3. ULF wave electromagnetic energy flux into the ionosphere: Joule heating implications

    NASA Astrophysics Data System (ADS)

    Hartinger, M. D.; Moldwin, M. B.; Zou, S.; Bonnell, J. W.; Angelopoulos, V.

    2015-01-01

    Ultralow-frequency (ULF) waves—in particular, Alfvén waves-transfer energy into the Earth's ionosphere via Joule heating, but it is unclear how much they contribute to global and local heating rates relative to other energy sources. In this study we use Time History of Events and Macroscale Interactions during Substorms satellite data to investigate the spatial, frequency, and geomagnetic activity dependence of the ULF wave Poynting vector (electromagnetic energy flux) mapped to the ionosphere. We use these measurements to estimate Joule heating rates, covering latitudes at or below the nominal auroral oval and below the open/closed field line boundary. We find ULF wave Joule heating rates (integrated over 3-30 mHz frequency band) typically range from 0.001 to 1 mW/m2. We compare these rates to empirical models of Joule heating associated with large-scale, static (on ULF wave timescales) current systems, finding that ULF waves nominally contribute little to the global, integrated Joule heating rate. However, there are extreme cases with ULF wave Joule heating rates of ≥10 mW/m2—in these cases, which are more likely to occur when Kp ≥ 3, ULF waves make significant contributions to the global Joule heating rate. We also find ULF waves routinely make significant contributions to local Joule heating rates near the noon and midnight local time sectors, where static current systems nominally contribute less to Joule heating; the most important contributions come from lower frequency (<7 mHz) waves.

  4. Diamond Heat-Spreader for Submillimeter-Wave Frequency Multipliers

    NASA Technical Reports Server (NTRS)

    Lin, Robert H.; Schlecht, Erich T.; Chattopadhyay, Goutam; Gill, John J.; Mehdi, Imran; Siegel, Peter H.; Ward, John S.; Lee, Choonsup; Thomas, Bertrand C.; Maestrini, Alain

    2010-01-01

    The planar GaAs Shottky diode frequency multiplier is a critical technology for the local oscillator (LO) for submillimeter- wave heterodyne receivers due to low mass, tenability, long lifetime, and room-temperature operation. The use of a W-band (75-100 GHz) power amplifier followed by a frequency multiplier is the most common for submillimeter-wave sources. Its greatest challenge is to provide enough input power to the LO for instruments onboard future planetary missions. Recently, JPL produced 800 mW at 92.5 GHz by combining four MMICs in parallel in a balanced configuration. As more power at W-band is available to the multipliers, their power-handling capability be comes more important. High operating temperatures can lead to degradation of conversion efficiency or catastrophic failure. The goal of this innovation is to reduce the thermal resistance by attaching diamond film as a heat-spreader on the backside of multipliers to improve their power-handling capability. Polycrystalline diamond is deposited by hot-filament chemical vapor deposition (CVD). This diamond film acts as a heat-spreader to both the existing 250- and 300-GHz triplers, and has a high thermal conductivity (1,000-1,200 W/mK). It is approximately 2.5 times greater than copper (401 W/mK) and 20 times greater than GaAs (46 W/mK). It is an electrical insulator (resistivity approx. equals 10(exp 15) Ohms-cm), and has a low relative dielectric constant of 5.7. Diamond heat-spreaders reduce by at least 200 C at 250 mW of input power, compared to the tripler without diamond, according to thermal simulation. This superior thermal management provides a 100-percent increase in power-handling capability. For example, with this innovation, 40-mW output power has been achieved from a 250-GHz tripler at 350-mW input power, while the previous triplers, without diamond, suffered catastrophic failures. This breakthrough provides a stepping-stone for frequency multipliers-based LO up to 3 THz. The future work

  5. Long-term variability of heat waves in Argentina and recurrence probability of the severe 2008 heat wave in Buenos Aires

    NASA Astrophysics Data System (ADS)

    Rusticucci, Matilde; Kyselý, Jan; Almeira, Gustavo; Lhotka, Ondřej

    2016-05-01

    Heat waves are one of the main concerns related to the impacts of climate change, because their frequency and severity are projected to increase in a future climate. The objectives of this work are to study the long-term variability of heat waves over Argentina and to estimate recurrence probability of the most severe 2008 heat wave in Buenos Aires. We used three definitions of heat waves that were based on (1) daily maximum temperature above the 90th percentile (MaxTHW), (2) daily minimum temperature above the 90th percentile (MinTHW) and (3) both maximum and minimum temperatures above the corresponding 90th percentiles (EHW). The minimum length of a heat wave was 3 days, and the analysis was performed over the October-March period. Decadal values in Buenos Aires experienced clear increases in heat waves according to MinTHW and EHW, with the highest frequency for both in the 2001-2010 decade, but at other stations, combinations of different trends and decadal variability resulted in some cases in a decrease of extreme heat waves. In the north-western part of the country, a strong positive change in the last decade was found, mainly due to the increment in the persistence of MinTHW but also accompanied by increases in MaxTHW. In general, other stations show a clear positive trend in MinTHW and decadal variability in MaxTHW, with the largest EHW cases in the last decade. We also estimated recurrence probability of the longest and most severe heat wave in Buenos Aires (over 1909-2010, according to intensity measured by the cumulative excess of maximum daily temperature above the 90th percentile) that occurred from 3 to 14 November 2008, by means of simulations with a stochastic first-order autoregressive model. The recurrence probability of such long and severe heat wave is small in the present climate but it is likely to increase substantially in the near future even under a moderate warming trend.

  6. The impact of the 2003 heat wave on mortality in Shanghai, China.

    PubMed

    Huang, Wei; Kan, Haidong; Kovats, Sari

    2010-05-01

    In 2003, Shanghai recorded the hottest summer in over 50years. We investigated the impact on the mortality of a heat wave in 2003 in Shanghai. We calculated excess mortality and rate ratios (RRs) during the heat wave (July 19-August 6, 2003) compared to a reference (non-heatwave) period (June 28-July 9, and August 16-August 22). During the heat wave, the RR of total mortality was 1.13 (95% CI: 1.06-1.20), and the impact was greatest for cardiovascular (RR=1.19, 95% CI: 1.08-1.32) and respiratory (RR=1.23, 95% CI: 1.02-1.48) mortality. Gender did not make a statistically significant difference for the heat-wave impact. Elderly people (over 65years) were most vulnerable to the heat wave. Our analysis showed that the 2003 heat wave had a substantial effect on mortality in Shanghai. Public health programs should be implemented to prevent heat wave-related health problems in the city. PMID:20219235

  7. Evaluation of the plan for surveillance and controlling of the effects of heat waves in Madrid

    NASA Astrophysics Data System (ADS)

    Culqui, Dante R.; Diaz, Julio; Simón, Fernando; Tobías, Aurelio; Linares, Cristina

    2014-10-01

    This paper presents evaluation of a plan for surveillance of and controlling the effects of heat-related mortality (PSCEHW), implemented in Madrid in 2004 through a time series analysis conducted with ARIMA modeling. From the public health point of view, prevention plans should be implemented as adaptive measures to heat waves. In 2003, the impact attributable to the heat wave was an increase in mortality per °C of 22.39 %. All heat waves since 2003 have been of lower intensity, and yet, in 2005 there was a heat wave of lower intensity that had a greater impact, i.e. an increase in mortality per °C of 45.71 %. With the methodology used here, we cannot say whether implementation of PSCEHW has resulted in a decrease of mortality attributable to high temperatures in the city of Madrid.

  8. Techniques that Link Extreme Events to the Large Scale, Applied to California Heat Waves

    NASA Astrophysics Data System (ADS)

    Grotjahn, R.

    2015-12-01

    Understanding the mechanisms how Californian Central Valley (CCV) summer extreme hot spells develop is very important since the events have major impacts on the economy and human safety. Results from a series of CCV heat wave studies will be presented, emphasizing the techniques used. Key larger scale elements are identified statistically that are also consistent with synoptic and dynamic understanding of what must be present during extreme heat. Beyond providing a clear synoptic explanation, these key elements have high predictability, in part because soil moisture has little annual variation in the heavily-irrigated CCV. In turn, the predictability naturally leads to an effective tool to assess climate model simulation of these heat waves in historical and future climate scenarios. (Does the model develop extreme heat for the correct reasons?) Further work identified that these large scale elements arise in two quite different ways: one from expansion southwestward of a pre-existing heat wave in southwest Canada, the other formed in place from parcels traversing the North Pacific. The pre-existing heat wave explains an early result showing correlation between heat waves in Sacramento California, and other locations along the US west coast, including distant Seattle Washington. CCV heat waves can be preceded by unusually strong tropical Indian Ocean and Indonesian convection, this partial link may occur through an Asian subtropical jet wave guide. Another link revealed by diagnostics is a middle and higher latitude source of wave activity in Siberia and East Asia that also leads to the development of the CCV heat wave. This talk will address as many of these results and the tools used to obtain them as is reasonable within the available time.

  9. Heating of ions by high frequency electromagnetic waves in magnetized plasmas

    SciTech Connect

    Zestanakis, P. A.; Kominis, Y.; Hizanidis, K.; Ram, A. K.

    2013-07-15

    The heating of ions by high frequency electrostatic waves in magnetically confined plasmas has been a paradigm for studying nonlinear wave-particle interactions. The frequency of the waves is assumed to be much higher than the ion cyclotron frequency and the waves are taken to propagate across the magnetic field. In fusion type plasmas, electrostatic waves, like the lower hybrid wave, cannot access the core of the plasma. That is a domain for high harmonic fast waves or electron cyclotron waves—these are primarily electromagnetic waves. Previous studies on heating of ions by two or more electrostatic waves are extended to two electromagnetic waves that propagate directly across the confining magnetic field. While the ratio of the frequency of each wave to the ion cyclotron frequency is large, the frequency difference is assumed to be near the ion cyclotron frequency. The nonlinear wave-particle interaction is studied analytically using a two time-scale canonical perturbation theory. The theory elucidates the effects of various parameters on the gain in energy by the ions—parameters such as the amplitudes and polarizations of the waves, the ratio of the wave frequencies to the cyclotron frequency, the difference in the frequency of the two waves, and the wave numbers associated with the waves. For example, the ratio of the phase velocity of the envelope formed by the two waves to the phase velocity of the carrier wave is important for energization of ions. For a positive ratio, the energy range is much larger than for a negative ratio. So waves like the lower hybrid waves will impart very little energy to ions. The theoretical results are found to be in good agreement with numerical simulations of the exact dynamical equations. The analytical results are used to construct mapping equations, simplifying the derivation of the motion of ions, which are, subsequently, used to follow the evolution of an ion distribution function. The heating of ions can then be

  10. HEATING THE SOLAR ATMOSPHERE BY THE SELF-ENHANCED THERMAL WAVES CAUSED BY THE DYNAMO PROCESSES

    SciTech Connect

    Dumin, Yurii V. E-mail: dumin@izmiran.ru

    2012-05-20

    We discuss a possible mechanism for heating the solar atmosphere by the ensemble of thermal waves, generated by the photospheric dynamo and propagating upward with increasing magnitudes. These waves are self-sustained and amplified due to the specific dependence of the efficiency of heat release by Ohmic dissipation on the ratio of the collisional to gyrofrequencies, which in its turn is determined by the temperature profile formed in the wave. In the case of sufficiently strong driving, such a mechanism can increase the plasma temperature by a few times, i.e., it may be responsible for heating the chromosphere and the base of the transition region.

  11. Heat acclimation improves intermittent sprinting in the heat but additional pre-cooling offers no further ergogenic effect.

    PubMed

    Castle, Paul; Mackenzie, Richard W; Maxwell, Neil; Webborn, Anthony D J; Watt, Peter W

    2011-08-01

    The aim of this study was to determine the effect of 10 days of heat acclimation with and without pre-cooling on intermittent sprint exercise performance in the heat. Eight males completed three intermittent cycling sprint protocols before and after 10 days of heat acclimation. Before acclimation, one sprint protocol was conducted in control conditions (21.8 ± 2.2°C, 42.8 ± 6.7% relative humidity) and two sprint protocols in hot, humid conditions (33.3 ± 0.6°C, 52.2 ± 6.8% relative humidity) in a randomized order. One hot, humid condition was preceded by 20 min of thigh pre-cooling with ice packs (-16.2 ± 4.5°C). After heat acclimation, the two hot, humid sprint protocols were repeated. Before heat acclimation, peak power output declined in the heat (P < 0.05) but pre-cooling prevented this. Ten days of heat acclimation reduced resting rectal temperature from 37.8 ± 0.3°C to 37.4 ± 0.3°C (P < 0.01). When acclimated, peak power output increased by ∼2% (P < 0.05, main effect) and no reductions in individual sprint peak power output were observed. Additional pre-cooling offered no further ergogenic effect. Unacclimated athletes competing in the heat should pre-cool to prevent reductions in peak power output, but heat acclimate for an increased peak power output. PMID:21777052

  12. Temperature, comfort and pollution levels during heat waves and the role of sea breeze.

    PubMed

    Papanastasiou, Dimitris K; Melas, Dimitris; Bartzanas, Thomas; Kittas, Constantinos

    2010-05-01

    During the summer of 2007 several Greek regions suffered periods of extreme heat, with midday temperatures of over 40 degrees C on several consecutive days. High temperatures were also recorded on the east coast of central Greece, where a complex sea breeze circulation system frequently develops. The more intense events occurred at the end of June and July. The highest temperatures were observed on 26 June and 25 July, while the sea breeze developed only on 25 July. Meteorological data collected at two sites-a coastal urban location and an inland suburban site that is not reached by the sea breeze flow-as well as pollution data collected at the urban site, were analysed in order to investigate the relationship between sea breeze development and the prevailing environmental conditions during these two heat wave events. The analysis revealed that sea breeze development affects temperature and pollution levels at the shoreline significantly, causing a decrease of approximately 4 degrees C from the maximum temperature value and an increase of approximately 30% in peak PM10 levels. Additionally, several stress indices were calculated in order to assess heat comfort conditions at the two sites. It was found that nocturnal comfort levels are determined mainly by the urban heat island effect, the intensity of which reaches up to 8 degrees C, while the applied indices do not demonstrate any significant daytime thermal stress relief due to sea breeze development. PMID:19936799

  13. Temperature, comfort and pollution levels during heat waves and the role of sea breeze.

    PubMed

    Papanastasiou, Dimitris K; Melas, Dimitris; Bartzanas, Thomas; Kittas, Constantinos

    2010-05-01

    During the summer of 2007 several Greek regions suffered periods of extreme heat, with midday temperatures of over 40 degrees C on several consecutive days. High temperatures were also recorded on the east coast of central Greece, where a complex sea breeze circulation system frequently develops. The more intense events occurred at the end of June and July. The highest temperatures were observed on 26 June and 25 July, while the sea breeze developed only on 25 July. Meteorological data collected at two sites-a coastal urban location and an inland suburban site that is not reached by the sea breeze flow-as well as pollution data collected at the urban site, were analysed in order to investigate the relationship between sea breeze development and the prevailing environmental conditions during these two heat wave events. The analysis revealed that sea breeze development affects temperature and pollution levels at the shoreline significantly, causing a decrease of approximately 4 degrees C from the maximum temperature value and an increase of approximately 30% in peak PM10 levels. Additionally, several stress indices were calculated in order to assess heat comfort conditions at the two sites. It was found that nocturnal comfort levels are determined mainly by the urban heat island effect, the intensity of which reaches up to 8 degrees C, while the applied indices do not demonstrate any significant daytime thermal stress relief due to sea breeze development.

  14. Heat transfer characteristics for some coolant additives used for water cooled engines

    SciTech Connect

    Abou-Ziyan, H.Z.; Helali, A.H.B.

    1996-12-31

    Engine coolants contain certain additives to prevent engine overheating or coolant freezing in cold environments. Coolants, also, contain corrosion and rust inhibitors, among other additives. As most engines are using engine cooling solutions, it is of interest to evaluate the effect of engine coolants on the boiling heat transfer coefficient. This has its direct impact on radiator size and environment. This paper describes the apparatus and the measurement techniques. Also, it presents the obtained boiling heat transfer results at different parameters. Three types of engine coolants and their mixtures in distilled water are evaluated, under sub-cooled and saturated boiling conditions. A profound effect of the presence of additives in the coolant, on heat transfer, was clear since changes of heat transfer for different coolants were likely to occur. The results showed that up to 180% improvement of boiling heat transfer coefficient is experienced with some types of coolants. However, at certain concentrations other coolants provide deterioration or not enhancement in the boiling heat transfer characteristics. This investigation proved that there are limitations, which are to be taken into consideration, for the composition of engine coolants in different environments. In warm climates, ethylene glycol should be kept at the minimum concentration required for dissolving other components, whereas borax is beneficial to the enhancement of the heat transfer characteristics.

  15. Forest response to heat waves at the dry timberline

    NASA Astrophysics Data System (ADS)

    Yakir, D.; Rotenberg, E.; Tatrinov, F.; Ogee, J.; Maseyk, K.

    2012-04-01

    Predictions of climate change consistently indicate continuous warming and drying for the entire Mediterranean basin and other regions during the next century. Investigating forest functioning at the current dry and hot "timberline" has therefore implications for predicting future forest distribution. In such investigations we should consider the forest adjustments to extreme conditions both at the long-term average climate basis, as at the time-scale of episodic extreme events, such as heat waves and droughts. Investigating both aspects in a 45-yr old semi-arid pine forest at the dry timberline (<300 mm annual rainfall) we observe adjustments that improve carbon-, nitrogen- and water- use efficiencies. An important aspect in the ecosystem sustainability is its ability to rapidly recover from extreme conditions, both at the short-term and the seasonal scale. A remarkable example is provided by the episodes (usually 2-4 days) of Easterly dry and hot air that are common in spring (so-called "Hamsin" events). During these events air temperature increases and relative humidity decreases within hours by 10˚C and 40%, respectively. Net ecosystem CO2 exchange (NEE) and photosynthesis (GPP) sharply decline, predominantly in response to the drastic increase in vapor pressure deficit (up to 6kPa), but then show full recovery to the pre-stress values within 24 h past the event. Similarly, following 5-6 months of seasonal drought, the forest resumes high photosynthetic activity within ~5 days following the first rain episode of about 10 mm in the fall. We show that these transient responses are useful in partitioning between the ecosystem responses to short-term atmosphere-driven stress and longer-term soil moisture stress. An ecosystem model (MuSICA) was used to test our understandings of underlying processes, and our ability to account for such differential responses.

  16. New thermal wave aspects on burn evaluation of skin subjected to instantaneous heating.

    PubMed

    Liu, J; Chen, X; Xu, L X

    1999-04-01

    Comparative studies on the well-known Pennes' equation and the newly developed thermal wave model of bioheat transfer (TWMBT) were performed to investigate the wave like behaviors of bioheat transfer occurred in thermal injury of biological bodies. The one-dimensional TWMBT in a finite medium was solved using separation of variables and the analytical solution showed distinctive wave behaviors of bioheat transfer in skin subjected to instantaneous heating. The finite difference method was used to simulate and study practical problems involved in burn injuries in which skin was stratified as three layers with various thermal physical properties. Deviations between the TWMBT and the traditional Pennes' equation imply that, for high flux heating with extremely short duration (i.e., flash fire), the TWMBT which accounts for finite thermal wave propagation may provide realistic predictions on burn evaluation. A general heat flux criterion has been established to determine when the thermal wave propagation dominates the principal heat transfer process and the TWMBT can be used for tissue temperature prediction and burn evaluation. A preliminary interpretation on the mechanisms of the wave like behaviors of heat transfer in living tissues was conducted. The application of thermal wave theory can also be possibly extended to other medical problems which involve instantaneous heating or cooling.

  17. MODEL FOR ALFVEN WAVE TURBULENCE IN SOLAR CORONAL LOOPS: HEATING RATE PROFILES AND TEMPERATURE FLUCTUATIONS

    SciTech Connect

    Asgari-Targhi, M.; Van Ballegooijen, A. A.

    2012-02-10

    It has been suggested that the solar corona may be heated by dissipation of Alfven waves that propagate up from the solar photosphere. According to this theory, counterpropagating Alfven waves are subject to nonlinear interactions that lead to turbulent decay of the waves and heating of the chromospheric and coronal plasma. To test this theory, better models for the dynamics of Alfven waves in coronal loops are required. In this paper, we consider wave heating in an active region observed with the Solar Dynamics Observatory in 2010 May. First a three-dimensional (3D) magnetic model of the region is constructed, and ten magnetic field lines that match observed coronal loops are selected. For each loop we construct a 3D magnetohydrodynamic model of the Alfven waves near the selected field line. The waves are assumed to be generated by footpoint motions inside the kilogauss magnetic flux elements at the two ends of the loop. Based on such models, we predict the spatial and temporal profiles of the heating along the selected loops. We also estimate the temperature fluctuations resulting from such heating. We find that the Alfven wave turbulence model can reproduce the observed characteristics of the hotter loops in the active region core, but the loops at the periphery of the region have large expansion factors and are predicted to be thermally unstable.

  18. Resonance in fast-wave amplitude in the periphery of cylindrical plasmas and application to edge losses of wave heating power in tokamaks

    NASA Astrophysics Data System (ADS)

    Perkins, R. J.; Hosea, J. C.; Bertelli, N.; Taylor, G.; Wilson, J. R.

    2016-07-01

    Heating magnetically confined plasmas using waves in the ion-cyclotron range of frequencies typically requires coupling these waves over a steep density gradient. This process has produced an unexpected and deleterious phenomenon on the National Spherical Torus eXperiment (NSTX): a prompt loss of wave power along magnetic field lines in front of the antenna to the divertor. Understanding this loss may be key to achieving effective heating and expanding the operational space of NSTX-Upgrade. Here, we propose that a new type of mode, which conducts a significant fraction of the total wave power in the low-density peripheral plasma, is driving these losses. We demonstrate the existence of such modes, which are distinct from surface modes and coaxial modes, in a cylindrical cold-plasma model when a half wavelength structure fits into the region outside the core plasma. The latter condition generalizes the previous hypothesis regarding the occurrence of the edge losses and may explain why full-wave simulations predict these losses in some cases but not others. If valid, this condition implies that outer gap control is a potential strategy for mitigating the losses in NSTX-Upgrade in addition to raising the magnetic field or influencing the edge density.

  19. Resonance in fast-wave amplitude in the periphery of cylindrical plasmas and application to edge losses of wave heating power in tokamaks

    DOE PAGES

    Perkins, R. J.; Hosea, J. C.; Bertelli, N.; Taylor, G.; Wilson, J. R.

    2016-07-01

    Heating magnetically confined plasmas using waves in the ion-cyclotron range of frequencies typically requires coupling these waves over a steep density gradient. Furthermore, this process has produced an unexpected and deleterious phenomenon on the National Spherical Torus eXperiment (NSTX): a prompt loss of wave power along magnetic field lines in front of the antenna to the divertor. Understanding this loss may be key to achieving effective heating and expanding the operational space of NSTX-Upgrade. Here, we propose that a new type of mode, which conducts a significant fraction of the total wave power in the low-density peripheral plasma, is drivingmore » these losses. We demonstrate the existence of such modes, which are distinct from surface modes and coaxial modes, in a cylindrical cold-plasma model when a half wavelength structure fits into the region outside the core plasma. The latter condition generalizes the previous hypothesis regarding the occurence of the edge losses and may explain why full-wave simulations predict these losses in some cases but not others. If valid, this condition implies that outer gap control is a potential strategy for mitigating the losses in NSTX-Upgrade in addition to raising the magnetic field or influencing the edge density.« less

  20. Generation of Acoustic-Gravity Waves in Ionospheric HF Heating Experiments: Simulating Large-Scale Natural Heat Sources

    NASA Astrophysics Data System (ADS)

    Pradipta, Rezy

    In this thesis, we investigate the potential role played by large-scale anomalous heat sources (e.g. prolonged heat wave events) in generating acoustic-gravity waves (AGWs) that might trigger widespread plasma turbulence in the ionospheric layer. The main hypothesis is that, the thermal gradients associated with the heat wave fronts could act as a source of powerful AGW capable of triggering ionospheric plasma turbulence over extensive areas. In our investigations, first we are going to examine a case study of the summer 2006 North American heat wave event. Our examination of GPS-derived total electron content (TEC) data over the North American sector reveals a quite noticeable increase in the level of daily plasma density fluctuations during the summer 2006 heat wave period. Comparison with the summer 2005 and summer 2007 data further confirms that the observed increase of traveling ionospheric disturbances (TIDs) during the summer 2006 heat wave period was not simply a regular seasonal phenomenon. Furthermore, a series of field experiments had been carried out at the High-frequency Active Auroral Research Program (HAARP) facility in order to physically simulate the process of AGW/TID generation by large-scale thermal gradients in the ionosphere. In these ionospheric HF heating experiments, we create some time-varying artificial thermal gradients at an altitude of 200--300 km above the Earth's surface using vertically-transmitted amplitude-modulated 0-mode HF heater waves. For our experiments, a number of radio diagnostic instruments had been utilized to detect the characteristic signatures of heater-generated AGW/TID. So far, we have been able to obtain several affirmative indications that some artificial AGW/TID are indeed being radiated out from the heated plasma volume during the HAARP-AGW experiments. Based on the experimental evidence, we may conclude that it is certainly quite plausible for large-scale thermal gradients associated with severe heat wave

  1. Electron Bernstein wave heating by electron cyclotron wave injection from the high-field side in LHD

    NASA Astrophysics Data System (ADS)

    Yoshimura, Y.; Igami, H.; Kubo, S.; Shimozuma, T.; Takahashi, H.; Nishiura, M.; Ohdachi, S.; Tanaka, K.; Ida, K.; Yoshinuma, M.; Suzuki, C.; Ogasawara, S.; Makino, R.; Idei, H.; Kumazawa, R.; Mutoh, T.; Yamada, H.; the LHD Experiment Group

    2013-06-01

    In the Large Helical Device (LHD), evident electron Bernstein wave (EBW) heating was successfully performed. The experiment was carried out using the electron cyclotron heating (ECH) system that was upgraded by installation of high-power, long-pulse 77 GHz gyrotrons. The EBW heating was achieved by a mode conversion from injected EC wave to EBW, by the so-called slow-XB technique where an X-mode wave is injected to the plasma from the high magnetic field side. The specific magnetic configuration of LHD provides a good opportunity to realize the slow-XB technique, which is generally difficult for tokamaks. With the slow-XB technique, increases in kinetically evaluated electron energy Wpe and electron temperature Te were observed in overdense plasmas. An electron heating in the so-called super dense core plasma in LHD, which is characterized with an internal diffusion barrier and a steep density gradient at the plasma core, was successfully demonstrated in the plasma core region where the central electron density ne0 of 17 × 1019 m-3 was about 1.2 times higher, at the beginning of the EC-wave injection, than the left-hand cut-off density of applied 77 GHz EC waves.

  2. Dust Heating through Alfvén waves using Generalized (r,q) distribution function.

    NASA Astrophysics Data System (ADS)

    Kiran, Zubia

    2012-07-01

    we used quasilinear theory to calculate the resonant heating of dust particles in a hot, collisionless and magnetized plasma through Alfven waves, using (r, q) distribution function. The linear (w ,k) relation for the electromagnetic dust cyclotron Alfven waves, evaluated by using the kinetic model. The effect of heating rate on the charge, density and mass of the dust species is subsequently investigated. The dependence of the heating rate on the indices (r) and (q) of the (r,q) distribution is also investigated. It has examine that the heating is sensitive to negative value of spectral index (r).

  3. Coupling of an acoustic wave to shear motion due to viscous heating

    NASA Astrophysics Data System (ADS)

    Liu, Bin; Goree, J.

    2016-07-01

    Viscous heating due to shear motion in a plasma can result in the excitation of a longitudinal acoustic wave, if the shear motion is modulated in time. The coupling mechanism is a thermal effect: time-dependent shear motion causes viscous heating, which leads to a rarefaction that can couple into a longitudinal wave, such as an acoustic wave. This coupling mechanism is demonstrated in an electrostatic three-dimensional (3D) simulation of a dusty plasma, in which a localized shear flow is initiated as a pulse, resulting in a delayed outward propagation of a longitudinal acoustic wave. This coupling effect can be profound in plasmas that exhibit localized viscous heating, such as the dusty plasma we simulated using parameters typical of the PK-4 experiment. We expect that a similar phenomenon can occur with other kinds of plasma waves.

  4. Characteristics of ion Bernstein wave heating in JIPPT-II-U tokamak

    SciTech Connect

    Okamoto, M.; Ono, M.

    1985-11-01

    Using a transport code combined with an ion Bernstein wave tokamak ray tracing code, a modelling code for the ion Bernstein wave heating has been developed. Using this code, the ion Bernstein wave heating experiment on the JIPPT-II-U tokamak has been analyzed. It is assumed that the resonance layer is formed by the third harmonic of deuterium-like ions, such as fully ionized carbon, and oxygen ions near the plasma center. For wave absorption mechanisms, electron Landau damping, ion cyclotron harmonic damping, and collisional damping are considered. The characteristics of the ion Bernstein wave heating experiment, such as the ion temperature increase, the strong dependence of the quality factor on the magnetic field strength, and the dependence of the ion temperature increment on the input power, are well reproduced.

  5. When will unusual heat waves become normal in a warming Africa?

    NASA Astrophysics Data System (ADS)

    Russo, Simone; Marchese, Andrea F.; Sillmann, Jana; Imme', Giuseppina

    2016-04-01

    Africa is one of the most vulnarable continent to climate change. In the upcoming decades the occurrence of longer, hotter and more frequent heat waves could have a strong impact on mortality and crop production. Here, by applying the Heat Wave Magnitude Index daily (HWMId) to temperature reanalysis data, we quantify the magnitude and the spatial extent of the most extreme heat waves experienced in Africa between 1979 and July 2015. Our results show that all these events had lower magnitude and spatial extent than the most unusual heat wave of the present era that occurred in Russia in 2010. The latter is compared with regional climate projections suggesting that in Africa an event of similar magnitude will become normal by 2040 under the most severe IPCC AR5 scenario (i.e. RCP8.5), when annual mean temperatures are projected to be 1.5oC warmer compared to current climate.

  6. Advances in High Harmonic Fast Wave Heating of NSTX H-mode Plasmas

    SciTech Connect

    Ryan, Philip Michael; Ahn, Joonwook; Bell, R. E.; Bonoli, P.; Chen, Guangye; Green, David L; Harvey, R. W.; Hosea, J.; Jaeger, Erwin Frederick; Kaye, S.; LeBlanc, B; Maingi, Rajesh; Phillips, Cynthia; Podesta, M.; Taylor, G.; Wilgen, John B; Wilson, J. R.

    2010-01-01

    High-harmonic fast wave (HHFW) heating and current drive is being developed in NSTX to provide bulk electron heating and q(0) control during non-inductively sustained Hmode plasmas fuelled by deuterium neutral-beam injection (NBI). In addition, it is used to assist the plasma current ramp-up. A major modification to increase the RF power limit was made in 2009; the original end-grounded, single end-powered current straps of the 12- element array were replaced with center-grounded, double end-powered straps. Greater than 3 MW have been coupled into NBI-driven, ELMy H-mode plasmas with this upgraded antenna. Improved core HHFW heating, particularly at longer wavelengths and during low-density start-up and plasma current ramp-up, has been obtained by lowering the edge density with lithium wall conditioning, thereby moving the critical density for fast-wave propagation away from the vessel wall [1]. Significant core electron heating of NBI-fuelled H-modes has been observed for the first time over a range of launched wavelengths and H-modes can be accessed by HHFW alone. Visible and IR camera images of the antenna and divertor indicate that fast wave interactions can deposit considerable RF energy on the outboard divertor plate, especially at longer wavelengths that begin to propagate closer to the vessel walls. Edge power loss can also arise from HHFWgenerated parametric decay instabilities; edge ion heating is observed that is wavelength dependent. During plasmas where HHFW is combined with NBI, there is a significant enhancement in neutron rate, and fast-ion D-alpha (FIDA) emission measurements clearly show broadening of the fast-ion profile in the plasma core. Large edge localized modes (ELMs) have been observed immediately following the termination of RF power, whether the power turn off is programmed or due to antenna arcing. Causality has not been established but new experiments are planned and will be reported. Fast digitization of the reflected power signal

  7. Propagation of the shock wave generated from excimer laser heating of aluminum targets in comparison with ideal blast wave theory

    NASA Astrophysics Data System (ADS)

    Jeong, S. H.; Greif, R.; Russo, R. E.

    1998-05-01

    Propagation of the shock wave generated during pulsed laser heating of aluminum targets was measured utilizing a probe beam deflection technique. The transit time of the laser-generated shock wave was compared with that predicted from the Sedov-Taylor solution for an ideal spherical blast wave. It was found that the most important parameters for the laser-generated shock wave to be consistent with the theoretically predicted propagation are the ambient pressure and the laser beam spot size. The prediction for laser energy conversion into the laser-induced vapor flow using the Sedov-Taylor solution overestimated the energy coupling efficiency, indicating a difference between a laser-induced gas-dynamic flow and an ideal blast wave.

  8. Mapping heat wave risk in the UK: Proactive planning for the 2050s

    NASA Astrophysics Data System (ADS)

    Oven, Katie; Reaney, Sim; Ohlemüller, Ralf; Nodwell, Sarah; Curtis, Sarah; Riva, Mylène; Dunn, Christine; Val, Dimitri; Burkhard, Roland

    2010-05-01

    Climate change projections suggest an increased frequency of heat waves in the UK over the coming decades. Such extreme events pose a serious threat to human health and are likely to impact upon health and social care systems and the infrastructures supporting them. This stress will result from both increased demands upon healthcare services and the ability of the infrastructure to cope, such as sufficient climate control in hospitals. Certain sectors of the population, such as older people, have an increased susceptibility to heat waves and hence are the focus of this research. There is no universal definition of a heat wave, reflecting the acclimatisation of a population. Based on a review of the literature, this research therefore sets out a series of working definitions of a heat wave in the UK context from a human health perspective. Drawing on these definitions, the UK heat wave hazard was mapped for the 2050s (2040-2069) using daily minimum and maximum temperature data derived from the UKCP09 Weather Generator at 50 km resolution. The analysis was undertaken for the three different greenhouse gas emissions scenarios within UKCP09 (low, medium and high). Hot spots of increased heat wave risk were identified and comparisons made between the various model outputs. These data were then combined with demographic forecasts for the 2050s enabling the identification of areas with an ageing population. Results are presented showing the scale of the projected change in heat wave risk across the UK and the location of older people. These results will be used in proactive planning to help policymakers and practitioners respond more appropriately to the needs of vulnerable populations in the coming decades. Key words: climate change; heat wave; risk mapping; vulnerability; risk reduction.

  9. Long-term statistical analysis on hot days and heat wave in Mongolia

    NASA Astrophysics Data System (ADS)

    Erdenebat, E.; Sato, T.

    2014-12-01

    In this study, 40 years of hot day and heat wave in Mongolia is investigated. Hot days carry difficulties and losses for Mongolian economy and daily life, such as people and livestock fell unfavorable (ill affected), agriculture losses, drying small rivers and lakes, causing steppe fires and etc. The hot day is one of the severe weather extreme in Mongolia, and their frequency and intensity have been increasing and becoming more severe. Intensive and longer-lasted hot days break out a heat wave event. Therefore, a monitoring of hot day and heat wave's occurrence and its long-term change are in nationwide scale. Longer prolonged heat wave may one of the causes for drought initiation while occurrence of drought has noticeably increased since last decade, which it is consistent with the heat wave occurrence. We analyzed maximum air temperature and precipitation data at 12 stations obtained from National Agency for Meteorology and Environment Monitoring (NAMEM) of Mongolia. Definition of the hot day is calculated by each station from reference period (1971-2000) and the heat wave is defined by when the daily maximum air temperature is 5K higher than the daily climatology of the reference period and lasted more than 4 consecutive days. Spatial distribution of long-term mean heat wave occurrence suggests that two areas, in Siberia and Mongolia, show high frequency. Those two areas are separated each other. Time series analysis indicates that the frequency kept similar level in 1970s and 1980s. In last two decade, however, heat wave was increased in central Mongolia in 1990s and northern half of Mongolia in 2000s as well as Western and Eastern Siberia.

  10. A protocol to assess insect resistance to heat waves, applied to bumblebees (Bombus Latreille, 1802).

    PubMed

    Martinet, Baptiste; Lecocq, Thomas; Smet, Jérémy; Rasmont, Pierre

    2015-01-01

    Insect decline results from numerous interacting factors including climate change. One of the major phenomena related to climate change is the increase of the frequency of extreme events such as heat waves. Since heat waves are suspected to dramatically increase insect mortality, there is an urgent need to assess their potential impact. Here, we determined and compared the resistance to heat waves of insects under hyperthermic stress through their time before heat stupor (THS) when they are exposed to an extreme temperature (40°C). For this, we used a new experimental standardised device available in the field or in locations close to the field collecting sites. We applied this approach on different Arctic, Boreo-Alpine and Widespread bumblebee species in order to predict consequences of heat waves. Our results show a heat resistance gradient: the heat stress resistance of species with a centred arctic distribution is weaker than the heat resistance of the Boreo-Alpine species with a larger distribution which is itself lower than the heat stress resistance of the ubiquitous species.

  11. A Protocol to Assess Insect Resistance to Heat Waves, Applied to Bumblebees (Bombus Latreille, 1802)

    PubMed Central

    Martinet, Baptiste; Lecocq, Thomas; Smet, Jérémy; Rasmont, Pierre

    2015-01-01

    Insect decline results from numerous interacting factors including climate change. One of the major phenomena related to climate change is the increase of the frequency of extreme events such as heat waves. Since heat waves are suspected to dramatically increase insect mortality, there is an urgent need to assess their potential impact. Here, we determined and compared the resistance to heat waves of insects under hyperthermic stress through their time before heat stupor (THS) when they are exposed to an extreme temperature (40°C). For this, we used a new experimental standardised device available in the field or in locations close to the field collecting sites. We applied this approach on different Arctic, Boreo-Alpine and Widespread bumblebee species in order to predict consequences of heat waves. Our results show a heat resistance gradient: the heat stress resistance of species with a centred arctic distribution is weaker than the heat resistance of the Boreo-Alpine species with a larger distribution which is itself lower than the heat stress resistance of the ubiquitous species. PMID:25738862

  12. High-frequency acoustic waves are not sufficient to heat the solar chromosphere.

    PubMed

    Fossum, Astrid; Carlsson, Mats

    2005-06-16

    One of the main unanswered questions in solar physics is why the Sun's outer atmosphere is hotter than its surface. Theory predicts abundant production of high-frequency (10-50 mHz) acoustic waves in subsurface layers of the Sun, and such waves are believed by many to constitute the dominant heating mechanism of the chromosphere (the lower part of the outer solar atmosphere) in non-magnetic regions. Such high-frequency waves are difficult to detect because of high-frequency disturbances in Earth's atmosphere (seeing) and other factors. Here we report the detection of high-frequency waves, and we use numerical simulations to show that the acoustic energy flux of these waves is too low, by a factor of at least ten, to balance the radiative losses in the solar chromosphere. Acoustic waves therefore cannot constitute the dominant heating mechanism of the solar chromosphere. PMID:15959510

  13. HEAT: High accuracy extrapolated ab initio thermochemistry. III. Additional improvements and overview.

    SciTech Connect

    Harding, M. E.; Vazquez, J.; Ruscic, B.; Wilson, A. K.; Gauss, J.; Stanton, J. F.; Chemical Sciences and Engineering Division; Univ. t Mainz; The Univ. of Texas; Univ. of North Texas

    2008-01-01

    Effects of increased basis-set size as well as a correlated treatment of the diagonal Born-Oppenheimer approximation are studied within the context of the high-accuracy extrapolated ab initio thermochemistry (HEAT) theoretical model chemistry. It is found that the addition of these ostensible improvements does little to increase the overall accuracy of HEAT for the determination of molecular atomization energies. Fortuitous cancellation of high-level effects is shown to give the overall HEAT strategy an accuracy that is, in fact, higher than most of its individual components. In addition, the issue of core-valence electron correlation separation is explored; it is found that approximate additive treatments of the two effects have limitations that are significant in the realm of <1 kJ mol{sup -1} theoretical thermochemistry.

  14. Whistler mode waves and the electron heat flux in the solar wind: cluster observations

    SciTech Connect

    Lacombe, C.; Alexandrova, O.; Cornilleau-Wehrlin, N.; Mangeney, A.; De Conchy, Y.; Maksimovic, M.; Matteini, L.; Santolík, O.

    2014-11-20

    The nature of the magnetic field fluctuations in the solar wind between the ion and electron scales is still under debate. Using the Cluster/STAFF instrument, we make a survey of the power spectral density and of the polarization of these fluctuations at frequencies f in [1, 400] Hz, during five years (2001-2005), when Cluster was in the free solar wind. In ∼10% of the selected data, we observe narrowband, right-handed, circularly polarized fluctuations, with wave vectors quasi-parallel to the mean magnetic field, superimposed on the spectrum of the permanent background turbulence. We interpret these coherent fluctuations as whistler mode waves. The lifetime of these waves varies between a few seconds and several hours. Here, we present, for the first time, an analysis of long-lived whistler waves, i.e., lasting more than five minutes. We find several necessary (but not sufficient) conditions for the observation of whistler waves, mainly a low level of background turbulence, a slow wind, a relatively large electron heat flux, and a low electron collision frequency. When the electron parallel beta factor β {sub e∥} is larger than 3, the whistler waves are seen along the heat flux threshold of the whistler heat flux instability. The presence of such whistler waves confirms that the whistler heat flux instability contributes to the regulation of the solar wind heat flux, at least for β {sub e∥} ≥ 3, in slow wind at 1 AU.

  15. Whistler Mode Waves and the Electron Heat Flux in the Solar Wind: Cluster Observations

    NASA Astrophysics Data System (ADS)

    Lacombe, C.; Alexandrova, O.; Matteini, L.; Santolík, O.; Cornilleau-Wehrlin, N.; Mangeney, A.; de Conchy, Y.; Maksimovic, M.

    2014-11-01

    The nature of the magnetic field fluctuations in the solar wind between the ion and electron scales is still under debate. Using the Cluster/STAFF instrument, we make a survey of the power spectral density and of the polarization of these fluctuations at frequencies f in [1, 400] Hz, during five years (2001-2005), when Cluster was in the free solar wind. In ~10% of the selected data, we observe narrowband, right-handed, circularly polarized fluctuations, with wave vectors quasi-parallel to the mean magnetic field, superimposed on the spectrum of the permanent background turbulence. We interpret these coherent fluctuations as whistler mode waves. The lifetime of these waves varies between a few seconds and several hours. Here, we present, for the first time, an analysis of long-lived whistler waves, i.e., lasting more than five minutes. We find several necessary (but not sufficient) conditions for the observation of whistler waves, mainly a low level of background turbulence, a slow wind, a relatively large electron heat flux, and a low electron collision frequency. When the electron parallel beta factor β e∥ is larger than 3, the whistler waves are seen along the heat flux threshold of the whistler heat flux instability. The presence of such whistler waves confirms that the whistler heat flux instability contributes to the regulation of the solar wind heat flux, at least for β e∥ >= 3, in slow wind at 1 AU.

  16. Proper use of sludge-control additives in residential heating oil systems

    SciTech Connect

    Tatnall, R.E.

    1995-04-01

    Discussed are various aspects of heating oil `sludge`: How it forms, typical problems it causes, how sludge-control additives work, what should be expected of them, and what happens in a contaminated system when such additives are used. Test results from laboratory and field experiments demonstrate that performance of commercially available additives varies greatly. The concept of `end-of-the-line` treatment is described and compared with bulk fuel treatment. A procedure is described whereby a retailer can test additives himself, and thus determine just what those additives will or will not do for his business. Finally, the economics of an effective treatment program are outlined.

  17. Another self-similar blast wave: Early time asymptote with shock heated electrons and high thermal conductivity

    NASA Technical Reports Server (NTRS)

    Cox, D. P.; Edgar, R. J.

    1982-01-01

    Accurate approximations are presented for the self-similar structures of nonradiating blast waves with adiabatic ions, isothermal electrons, and equation ion and electron temperatures at the shock. The cases considered evolve in cavities with power law ambient densities (including the uniform density case) and have negligible external pressure. The results provide the early time asymptote for systems with shock heating of electrons and strong thermal conduction. In addition, they provide analytical results against which two fluid numerical hydrodynamic codes can be checked.

  18. Microwave and Millimeter Wave Testing for the Inspection of the Space Shuttle Spray on Foam Insulations (SOFI) and the Acreage Heat Tiles

    NASA Technical Reports Server (NTRS)

    Zoughi, R.; Kharkovsky, S.; Hepburn, F. L.

    2005-01-01

    The utility of microwave and millimeter wave nondestructive testing and evaluation (NDT&E) methods, for testing the Space Shuttle's external he1 tank spray on foam insulation (SOFI) and the acreage heat tiles has been investigated during the past two years. Millimeter wave NDE techniques are capable of producing internal images of SOFI. This paper presents the results of testing several diverse panels with embedded voids and debonds at millimeter wave frequencies. Additionally, the results of testing a set of heat tiles are also presented. Finally, the attributes of these methods as well as the advantageous features associated with these systems are also provided.

  19. Simulations of heavy ion heating by electromagnetic ion cyclotron waves driven by proton temperature anisotropies

    NASA Technical Reports Server (NTRS)

    Tanaka, M.

    1985-01-01

    Heating of heavy ions by the electromagnetic ion cyclotron (EMIC) waves, which are driven by proton temperature anisotropies, is studied by means of hybrid particle simulations. Initially, relaxation of the temperature anisotropies in the proton distribution and isotropic heating of the heavy ions are observed (phase I), followed by substantial perpendicular heating of the heavy ions (phase II). The heavy ions are distinctly gyrophase modulated by the EMIC waves. The isotropic heating in phase I is due to magnetic trapping by the excited proton cyclotron waves. The perpendicular heating in phase II is attributed to cyclotron resonance with the EMIC waves, which becomes possible by means of the preceding heating in phase I. Saturation of the EMIC instability is instead attributed to magnetic trapping of the majority ions: protons. When the proton anisotropy is very large, frequency shift (decrease) of the proton cyclotron waves to less than 1/2 Ohm(p) is observed. The present mechanism is not only relevant to He(+) heating in the dayside equator of the magnetosphere, but it also predicts hot He2(+) ions behind the earth's bow shock.

  20. The 1994 heat wave in South Korea: mortality impacts and recurrence probability in a changing climate

    NASA Astrophysics Data System (ADS)

    Kysely, J.; Kim, J.

    2010-03-01

    The study deals with mortality impacts of the July-August 1994 heat wave in the population of South Korea, including the megacity of Seoul (with the population exceeding 10 million for the city and 20 million for the metropolitan area), and estimates recurrence probability of the heat wave in a changing climate in terms of simulations of daily temperature series with a stochastic model. The 1994 heat wave is found exceptional with respect to both climatological characteristics and the mortality effects: significantly elevated mortality occurred in all population groups, including children up to 14 years of age, and the total death toll exceeded 3000 in the Korean population, which ranks the 1994 heat wave among the worst weather-related disasters in East Asia. The estimate represents net excess mortality as no mortality displacement effect appeared. A comparison with other documented natural disasters shows that the death toll of the heat wave was much higher than those of the most disastrous floodings and typhoons over Korean Peninsula in the 20th century. The mortality response was stronger in males than females although males are found to be less vulnerable during average heat waves. A climatological analysis reveals that the July-August 1994 heat wave might be considered an extremely rare event with a return period in the order of hundreds of years if stationarity of temperature time series is assumed. However, under a more realistic assumption of gradual warming related to climate change, recurrence probability of an event analogous to the 1994 heat wave sharply rises for near-future time horizons. If warming of 0.04°C/year is assumed over 2001-2060, the recurrence interval of a very long spell of days with temperature exceeding a high threshold (as in the 1994 heat wave) is estimated to decrease to around 40 (10) years in the 2021-2030 (2041-2050) decade. This emphasizes the need for setting up an efficient heat-watch-warning system in this area in order to

  1. Control of terahertz emission in photoconductive antennas through an additional optical continuous wave.

    PubMed

    Bockelt, A; Palací, J; Vidal, B

    2013-08-15

    The manipulation of the operating conditions of photoconductive antennas by means of an additional continuous wave (CW) is reported. It is used to control a fiber-based terahertz (THz) time-domain-spectroscopy system at telecom wavelengths. The injection of an optical CW into the transmitter allows the control of the THz amplitude without causing major degradation to the system performance. This, for instance, can be exploited to perform modulation of the THz signal. PMID:24104665

  2. Effects of Simulated Heat Waves with Strong Sudden Cooling Weather on ApoE Knockout Mice

    PubMed Central

    Zhang, Shuyu; Kuang, Zhengzhong; Zhang, Xiakun

    2015-01-01

    This study analyzes the mechanism of influence of heat waves with strong sudden cooling on cardiovascular diseases (CVD) in ApoE−/− mice. The process of heat waves with strong sudden cooling was simulated with a TEM1880 meteorological-environment simulation chamber according to the data obtained at 5 a.m. of 19 June 2006 to 11 p.m. of 22 June 2006. Forty-eight ApoE−/− mice were divided into six blocks based on their weight. Two mice from each block were randomly assigned to control, heat wave, temperature drop, and rewarming temperature groups. The experimental groups were transferred into the climate simulator chamber for exposure to the simulated heat wave process with strong sudden temperature drop. After 55, 59, and 75 h of exposure, the experimental groups were successively removed from the chamber to monitor physiological indicators. Blood samples were collected by decollation, and the hearts were harvested in all groups. The levels of heat stress factors (HSP60, SOD, TNF, sICAM-1, HIF-1α), cold stress factors (NE, EPI), vasoconstrictor factors (ANGII, ET-1, NO), and four items of blood lipid (TC, TG, HDL-C, and LDL-C) were measured in each ApoE−/− mouse. Results showed that the heat waves increased the levels of heat stress factors except SOD decreased, and decreased the levels of vasoconstrictor factors and blood lipid factors except TC increased. The strong sudden temperature drop in the heat wave process increased the levels of cold stress factors, vasoconstrictor factors and four blood lipid items (except the level of HDL-C which decreased) and decreased the levels of heat stress factors (except the level of SOD which increased). The analysis showed that heat waves could enhance atherosclerosis of ApoE−/− mice. The strong sudden temperature drop during the heat wave process increased the plasma concentrations of NE and ANGII, which indicates SNS activation, and resulted in increased blood pressure. NE and ANGII are vasoconstrictors

  3. Effects of Simulated Heat Waves with Strong Sudden Cooling Weather on ApoE Knockout Mice.

    PubMed

    Zhang, Shuyu; Kuang, Zhengzhong; Zhang, Xiakun

    2015-05-26

    This study analyzes the mechanism of influence of heat waves with strong sudden cooling on cardiovascular diseases (CVD) in ApoE-/- mice. The process of heat waves with strong sudden cooling was simulated with a TEM1880 meteorological-environment simulation chamber according to the data obtained at 5 a.m. of 19 June 2006 to 11 p.m. of 22 June 2006. Forty-eight ApoE-/- mice were divided into six blocks based on their weight. Two mice from each block were randomly assigned to control, heat wave, temperature drop, and rewarming temperature groups. The experimental groups were transferred into the climate simulator chamber for exposure to the simulated heat wave process with strong sudden temperature drop. After 55, 59, and 75 h of exposure, the experimental groups were successively removed from the chamber to monitor physiological indicators. Blood samples were collected by decollation, and the hearts were harvested in all groups. The levels of heat stress factors (HSP60, SOD, TNF, sICAM-1, HIF-1α), cold stress factors (NE, EPI), vasoconstrictor factors (ANGII, ET-1, NO), and four items of blood lipid (TC, TG, HDL-C, and LDL-C) were measured in each ApoE-/- mouse. Results showed that the heat waves increased the levels of heat stress factors except SOD decreased, and decreased the levels of vasoconstrictor factors and blood lipid factors except TC increased. The strong sudden temperature drop in the heat wave process increased the levels of cold stress factors, vasoconstrictor factors and four blood lipid items (except the level of HDL-C which decreased) and decreased the levels of heat stress factors (except the level of SOD which increased). The analysis showed that heat waves could enhance atherosclerosis of ApoE-/- mice. The strong sudden temperature drop during the heat wave process increased the plasma concentrations of NE and ANGII, which indicates SNS activation, and resulted in increased blood pressure. NE and ANGII are vasoconstrictors involved in systemic

  4. Nonlinear traveling waves in a two-layer system with heat release/consumption at the interface

    NASA Astrophysics Data System (ADS)

    Simanovskii, Ilya B.; Viviani, Antonio; Dubois, Frank; Legros, Jean-Claude

    2016-06-01

    The influence of an interfacial heat release and heat consumption on nonlinear convective flows, developed under the joint action of buoyant and thermocapillary effects in a laterally heated two-layer system with periodic boundary conditions, is investigated. Regimes of traveling waves and modulated traveling waves have been obtained. It is found that rather intensive heat sinks at the interface can lead to the change of the direction of the waves' propagation.

  5. Recent Fast Wave Coupling and Heating Studies on NSTX, with Possible Implications for ITER

    SciTech Connect

    J.C. Hosea, R.E. Bell, E. Feibush, R.W. Harvey, E.F. Jaeger, B.P LeBlanc, R. Maingi, C.K. Phillips, L. Roquemore, P.M. Ryan, G. Taylor, K. Tritz, E.J. Valeo, J. Wilgen, J.R. Wilson, and the NSTX Team

    2009-07-21

    The goal of the high harmonic fast wave (HHFW) research on NSTX is to maximize the coupling of RF power to the core of the plasma by minimizing the coupling of RF power to edge loss processes. HHFW core plasma heating efficiency in helium and deuterium L-mode discharges is found to improve markedly on NSTX when the density 2 cm in front of the antenna is reduced below that for the onset of perpendicular wave propagation (nonset ∝ B*k|| 2/ω). In NSTX, the observed RF power losses in the plasma edge are driven in the vicinity of the antenna as opposed to resulting from multi-pass edge damping. PDI surface losses through ion-electron collisions are estimated to be significant. Recent spectroscopic measurements suggest that additional PDI losses could be caused by the loss of energetic edge ions on direct loss orbits and perhaps result in the observed clamping of the edge rotation. Initial deuterium H-mode heating studies reveal that core heating is degraded at lower kφ (- 8 m-1 relative to 13 m-1) as for the Lmode case at elevated edge density. Fast visible camera images clearly indicate that a major edge loss process is occurring from the plasma scrape off layer (SOL) in the vicinity of the antenna and along the magnetic field lines to the lower outer divertor plate. Large type I ELMs, which are observed at both kφ values, appear after antenna arcs caused by precursor blobs, low level ELMs, or dust. For large ELMs without arcs, the source reflection coefficients rise on a 0.1 ms time scale, which indicates that the time derivative of the reflection coefficient can be used to discriminate between arcs and ELMs.

  6. Additives

    NASA Technical Reports Server (NTRS)

    Smalheer, C. V.

    1973-01-01

    The chemistry of lubricant additives is discussed to show what the additives are chemically and what functions they perform in the lubrication of various kinds of equipment. Current theories regarding the mode of action of lubricant additives are presented. The additive groups discussed include the following: (1) detergents and dispersants, (2) corrosion inhibitors, (3) antioxidants, (4) viscosity index improvers, (5) pour point depressants, and (6) antifouling agents.

  7. Generation of whistler waves by continuous HF heating of the upper ionosphere

    NASA Astrophysics Data System (ADS)

    Vartanyan, A.; Milikh, G. M.; Eliasson, B. E.; Sharma, A.; Chang, C.; Parrot, M.; Papadopoulos, K.

    2013-12-01

    We report observations of VLF waves by the DEMETER satellite overflying the HAARP facility during ionospheric heating experiments. The detected VLF waves were in the range 8-17 kHz and coincided with times of continuous heating. The experiments indicate whistler generation due to conversion of artificial lower hybrid waves to whistlers on small scale field-aligned plasma density striations. The observations are compared with theoretical models, taking into account both linear and nonlinear processes. Implications of the mode conversion technique on VLF generation with subsequent injection into the radiation belts to trigger particle precipitation are discussed.

  8. Land surface thermal environment during heat wave event measured by satellite observation

    NASA Astrophysics Data System (ADS)

    Chen, Feng; Yang, Song

    2014-11-01

    In summer 2013, mainly from July to August, most parts of China continued to experience an unusually severe heat wave with exceptionally high air temperatures, based on the records measured at meteorological stations. As a supplement to the weather station networks, remotely sensed observation can quantify detailed variation of surface temperature at relatively high spatial resolution, owing to its ability to provide a complete and homogeneous data sources. In addition to the GHCN CAMS gridded land air surface temperature, land surface temperature products of MODIS including MOD11C3/MYD11C3 and MOD11A2/MYD11A2 were used to evaluate the anomaly of summertime thermal environment over the South China in 2013. To investigate the impacts of heat wave event on built environment, the MODIS Land Cover Type yearly product (MCD12Q1) was collected. Regional thermal anomaly was observed in both air and surface temperature measurements, especially for August. Statistics based on MOD11A2/MYD11A2 shows the spatio-temporal variation of land surface temperature at regional scale, and the heterogeneous characteristics in diurnal cycle are also shown. Compared with other types, the urban and built-up generally presents larger surface temperature at daytime. Detailed analyses were further conducted for three selected regions roughly covering the Yangtze River Delta, the Pearl River Delta, and the areas around Wuhan City respectively. Findings indicate that urban and built-up exhibits more distinct thermal contrast to its surroundings at daytime, in contrast to the situation at nighttime. This thermal contrast was defined as surface urban heat island intensity (UHII) calculated using a newly proposed procedure, in this paper. The UHII shows both time- and geography-dependent variations. Meanwhile, the UHII over medium and small cities was even more obvious and larger than that over megalopolitan areas. These preliminary findings suggest that land use and land cover changes as a

  9. Nonlinear heat transport between the stack and the heat-exchangers of standing-wave thermoacoustic refrigerators

    NASA Astrophysics Data System (ADS)

    Blanc-Benon, Ph.; Berson, A.

    2008-06-01

    The development of high performance thermoacoustic refrigerators requires an efficient heat transport between the stack and the heat exchangers. A 1D nonlinear model for the thermal coupling of these two components is proposed in the case of a standing-wave thermaocoustic refrigerator. It shows the generation of temperature harmonics close to the edges of the plates that affects heat transport. In order to validate the model, the nonlinear temperature field close to the stack edges is measured using cold-wire anemometry.

  10. Electron heating using lower hybrid waves in the PLT tokamak

    SciTech Connect

    Bell, R.E.; Bernabei, S.; Cavallo, A.; Chu, T.K.; Luce, T.; Motley, R.; Ono, M.; Stevens, J.; von Goeler, S.

    1987-06-01

    Lower hybrid waves with a narrow high velocity wave spectrum have been used to achieve high central electron temperatures in a tokamak plasma. Waves with a frequency of 2.45 GHz launched by a 16-waveguide grill at a power level less than 600 kW were used to increase the central electron temperature of the PLT plasma from 2.2 keV to 5 keV. The magnitude of the temperature increase depends strongly on the phase difference between the waveguides and on the direction of the launched wave. A reduction in the central electron thermal diffusivity is associated with the peaked electron temperature profiles of lower hybrid current-driven plasmas. 16 refs.

  11. Self-consistent full-wave and Fokker-Planck calculations for ion cyclotron heating in non-Maxwellian plasmasa)

    NASA Astrophysics Data System (ADS)

    Jaeger, E. F.; Berry, L. A.; Ahern, S. D.; Barrett, R. F.; Batchelor, D. B.; Carter, M. D.; D'Azevedo, E. F.; Moore, R. D.; Harvey, R. W.; Myra, J. R.; D'Ippolito, D. A.; Dumont, R. J.; Phillips, C. K.; Okuda, H.; Smithe, D. N.; Bonoli, P. T.; Wright, J. C.; Choi, M.

    2006-05-01

    Magnetically confined plasmas can contain significant concentrations of nonthermal plasma particles arising from fusion reactions, neutral beam injection, and wave-driven diffusion in velocity space. Initial studies in one-dimensional and experimental results show that nonthermal energetic ions can significantly affect wave propagation and heating in the ion cyclotron range of frequencies. In addition, these ions can absorb power at high harmonics of the cyclotron frequency where conventional two-dimensional global-wave models are not valid. In this work, the all-orders global-wave solver AORSA [E. F. Jaeger et al., Phys. Rev. Lett. 90, 195001 (2003)] is generalized to treat non-Maxwellian velocity distributions. Quasilinear diffusion coefficients are derived directly from the wave fields and used to calculate energetic ion velocity distributions with the CQL3D Fokker-Planck code [R. W. Harvey and M. G. McCoy, Proceedings of the IAEA Technical Committee Meeting on Simulation and Modeling of Thermonuclear Plasmas, Montreal, Canada, 1992 (USDOC NTIS Document No. DE93002962)]. For comparison, the quasilinear coefficients can be calculated numerically by integrating the Lorentz force equations along particle orbits. Self-consistency between the wave electric field and resonant ion distribution function is achieved by iterating between the global-wave and Fokker-Planck solutions.

  12. A new perspective on the 1930s mega-heat waves across central United States

    NASA Astrophysics Data System (ADS)

    Cowan, Tim; Hegerl, Gabi

    2016-04-01

    The unprecedented hot and dry conditions that plagued contiguous United States during the 1930s caused widespread devastation for many local communities and severely dented the emerging economy. The heat extremes experienced during the aptly named Dust Bowl decade were not isolated incidences, but part of a tendency towards warm summers over the central United States in the early 1930s, and peaked in the boreal summer 1936. Using high-quality daily maximum and minimum temperature observations from more than 880 Global Historical Climate Network stations across the United States and southern Canada, we assess the record breaking heat waves in the 1930s Dust Bowl decade. A comparison is made to more recent heat waves that have occurred during the latter half of the 20th century (i.e., in a warming world), both averaged over selected years and across decades. We further test the ability of coupled climate models to simulate mega-heat waves (i.e. most extreme events) across the United States in a pre-industrial climate without the impact of any long-term anthropogenic warming. Well-established heat wave metrics based on the temperature percentile threshold exceedances over three or more consecutive days are used to describe variations in the frequency, duration, amplitude and timing of the events. Casual factors such as drought severity/soil moisture deficits in the lead up to the heat waves (interannual), as well as the concurrent synoptic conditions (interdiurnal) and variability in Pacific and Atlantic sea surface temperatures (decadal) are also investigated. Results suggest that while each heat wave summer in the 1930s exhibited quite unique characteristics in terms of their timing, duration, amplitude, and regional clustering, a common factor in the Dust Bowl decade was the high number of consecutive dry seasons, as measured by drought indicators such as the Palmer Drought Severity and Standardised Precipitation indices, that preceded the mega-heat waves. This

  13. A Modeling Study of the On-Going Drought and Heat Wave over the United States

    NASA Technical Reports Server (NTRS)

    Schubert, S.; Wang, H.; Koster, R.; Suarez, M.

    2012-01-01

    Ensembles of AGCM experiments have been conducted to examine the causes of the on-going drought and heat wave affecting much of the United States. The results show that the drought and hot temperatures that have been especially severe over Texas and parts of Mexico since late 2010 are the result of a combination of SST forcing from both the tropical Pacific and the tropical Atlantic, with the latter playing a particularly important role during later half of the summer of 2011, and the warm SSTs off the East Coast contributing to the warm conditions along the East Coast. An extension of the model simulations into the summer of 2012 suggests that the warm conditions are again primarily driven by SST forcing - despite the return of the tropical Pacific to neutral conditions. The results of additional experiments currently being conducted to separate the influences of the 2012 SST anomalies in the various ocean basins will be discussed.

  14. Unsteady heat-flux measurements of second-mode instability waves in a hypersonic flat-plate boundary layer

    NASA Astrophysics Data System (ADS)

    Kegerise, Michael A.; Rufer, Shann J.

    2016-08-01

    In this paper, we report on the application of the atomic layer thermopile (ALTP) heat-flux sensor to the measurement of laminar-to-turbulent transition in a hypersonic flat-plate boundary layer. The centerline of the flat-plate model was instrumented with a streamwise array of ALTP sensors, and the flat-plate model was exposed to a Mach 6 freestream over a range of unit Reynolds numbers. Here, we observed an unstable band of frequencies that are associated with second-mode instability waves in the laminar boundary layer that forms on the flat-plate surface. The measured frequencies, group velocities, phase speeds, and wavelengths of these instability waves are consistent with data previously reported in the literature. Heat flux time series, and the Morlet wavelet transforms of them, revealed the wave-packet nature of the second-mode instability waves. In addition, a laser-based radiative heating system was used to measure the frequency response functions (FRF) of the ALTP sensors used in the wind tunnel test. These measurements were used to assess the stability of the sensor FRFs over time and to correct spectral estimates for any attenuation caused by the finite sensor bandwidth.

  15. Heating of solar chromosphere by electromagnetic wave absorption in a plasma slab model

    SciTech Connect

    Tsiklauri, D.; Pechhacker, R.

    2011-04-15

    The heating of solar chromospheric internetwork regions by means of the absorption of electromagnetic (EM) waves that originate from the photospheric blackbody radiation is studied in the framework of a plasma slab model. The absorption is provided by the electron-neutral collisions in which electrons oscillate in the EM wave field and electron-neutral collisions damp the EM wave. Given the uncertain nature of the collision cross-section due to the plasma microturbulence, it is shown that for plausible physical parameters, the heating flux produced by the absorption of EM waves in the chromosphere is between 20% and 45% of the chromospheric radiative loss flux requirement. It is also established that there is an optimal value for the collision cross-section, 5x10{sup -18} m{sup 2}, which produces the maximal heating flux of 1990 W m{sup -2}.

  16. Acceleration and heating of two-fluid solar wind by Alfven waves

    NASA Technical Reports Server (NTRS)

    Sandbaek, Ornulf; Leer, Egil

    1994-01-01

    Earlier model studies of solar wind driven by thermal pressure and Alfven waves have shown that wave amplitudes of 20-30 km/s at the coronal base are sufficient to accelerate the flow to the high speeds observed in quasi-steady streams emanating from large coronal holes. We focus on the energy balance in the proton gas and show that heat conduction from the region where the waves are dissipated may play an important role in determining the proton temperature at the orbit of Earth. In models with 'classical' heat conduction we find a correlation between high flow speed, high proton temperature, and low electron temperature at 1 AU. The effect of wave heating on the development of anisotropies in the solar wind proton gas pressure is also investigated in this study.

  17. Overview of Heat Addition and Efficiency Predictions for an Advanced Stirling Convertor

    NASA Technical Reports Server (NTRS)

    Wilson, Scott D.; Reid, Terry V.; Schifer, Nicholas A.; Briggs, Maxwell H.

    2012-01-01

    The U.S. Department of Energy (DOE) and Lockheed Martin Space Systems Company (LMSSC) have been developing the Advanced Stirling Radioisotope Generator (ASRG) for use as a power system for space science missions. This generator would use two high-efficiency Advanced Stirling Convertors (ASCs), developed by Sunpower Inc. and NASA Glenn Research Center (GRC). The ASCs convert thermal energy from a radioisotope heat source into electricity. As part of ground testing of these ASCs, different operating conditions are used to simulate expected mission conditions. These conditions require achieving a particular operating frequency, hot end and cold end temperatures, and specified electrical power output for a given net heat input. Microporous bulk insulation is used in the ground support test hardware to minimize the loss of thermal energy from the electric heat source to the environment. The insulation package is characterized before operation to predict how much heat will be absorbed by the convertor and how much will be lost to the environment during operation. In an effort to validate these predictions, numerous tasks have been performed, which provided a more accurate value for net heat input into the ASCs. This test and modeling effort included: (a) making thermophysical property measurements of test setup materials to provide inputs to the numerical models, (b) acquiring additional test data that was collected during convertor tests to provide numerical models with temperature profiles of the test setup via thermocouple and infrared measurements, (c) using multidimensional numerical models (computational fluid dynamics code) to predict net heat input of an operating convertor, and (d) using validation test hardware to provide direct comparison of numerical results and validate the multidimensional numerical models used to predict convertor net heat input. This effort produced high fidelity ASC net heat input predictions, which were successfully validated using

  18. THEMIS Observations of the Magnetopause Electron Diffusion Region: Large Amplitude Waves and Heated Electrons

    NASA Technical Reports Server (NTRS)

    Tang, Xiangwei; Cattell, Cynthia; Dombeck, John; Dai, Lei; Wilson, Lynn B. III; Breneman, Aaron; Hupack, Adam

    2013-01-01

    We present the first observations of large amplitude waves in a well-defined electron diffusion region based on the criteria described by Scudder et al at the subsolar magnetopause using data from one Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellite. These waves identified as whistler mode waves, electrostatic solitary waves, lower hybrid waves, and electrostatic electron cyclotron waves, are observed in the same 12 s waveform capture and in association with signatures of active magnetic reconnection. The large amplitude waves in the electron diffusion region are coincident with abrupt increases in electron parallel temperature suggesting strong wave heating. The whistler mode waves, which are at the electron scale and which enable us to probe electron dynamics in the diffusion region were analyzed in detail. The energetic electrons (approx. 30 keV) within the electron diffusion region have anisotropic distributions with T(sub e(right angle))/T(sub e(parallel)) > 1 that may provide the free energy for the whistler mode waves. The energetic anisotropic electrons may be produced during the reconnection process. The whistler mode waves propagate away from the center of the "X-line" along magnetic field lines, suggesting that the electron diffusion region is a possible source region of the whistler mode waves.

  19. Heat transfer in laminar wall boundary layer within noncentered unsteady expansion wave

    NASA Technical Reports Server (NTRS)

    Srinivasan, G.; Hall, J. G.

    1975-01-01

    The paper summarizes results of theoretical and experimental investigations of wall temperature change and heat transfer in the laminar boundary layer formed within noncentered unsteady expansion waves in shock tubes. The study is restricted to a class of noncentered plane waves which have one key feature in common with centered waves, i.e., the first derivatives of the inviscid flow quantities have values or are discontinuous at the wavehead. The wall temperature is calculated implicitly by matching the local heat transfer rates of gas and wall thermal boundary layers. Experimentally, the wall temperature was measured using a thin-film resistance thermometer and heat transfer was then deduced using a one-dimensional unsteady heat conduction equation.

  20. CORONAL HEATING BY SURFACE ALFVEN WAVE DAMPING: IMPLEMENTATION IN A GLOBAL MAGNETOHYDRODYNAMICS MODEL OF THE SOLAR WIND

    SciTech Connect

    Evans, R. M.; Opher, M.; Oran, R.; Van der Holst, B.; Sokolov, I. V.; Frazin, R.; Gombosi, T. I.; Vasquez, A.

    2012-09-10

    The heating and acceleration of the solar wind is an active area of research. Alfven waves, because of their ability to accelerate and heat the plasma, are a likely candidate in both processes. Many models have explored wave dissipation mechanisms which act either in closed or open magnetic field regions. In this work, we emphasize the boundary between these regions, drawing on observations which indicate unique heating is present there. We utilize a new solar corona component of the Space Weather Modeling Framework, in which Alfven wave energy transport is self-consistently coupled to the magnetohydrodynamic equations. In this solar wind model, the wave pressure gradient accelerates and wave dissipation heats the plasma. Kolmogorov-like wave dissipation as expressed by Hollweg along open magnetic field lines was presented in van der Holst et al. Here, we introduce an additional dissipation mechanism: surface Alfven wave (SAW) damping, which occurs in regions with transverse (with respect to the magnetic field) gradients in the local Alfven speed. For solar minimum conditions, we find that SAW dissipation is weak in the polar regions (where Hollweg dissipation is strong), and strong in subpolar latitudes and the boundaries of open and closed magnetic fields (where Hollweg dissipation is weak). We show that SAW damping reproduces regions of enhanced temperature at the boundaries of open and closed magnetic fields seen in tomographic reconstructions in the low corona. Also, we argue that Ulysses data in the heliosphere show enhanced temperatures at the boundaries of fast and slow solar wind, which is reproduced by SAW dissipation. Therefore, the model's temperature distribution shows best agreement with these observations when both dissipation mechanisms are considered. Lastly, we use observational constraints of shock formation in the low corona to assess the Alfven speed profile in the model. We find that, compared to a polytropic solar wind model, the wave

  1. Evidence for an Additional Heat Source in the Warm Ionized Medium of Galaxies.

    PubMed

    Reynolds; Haffner; Tufte

    1999-11-01

    Spatial variations of the [S ii]/Halpha and [N ii]/Halpha line intensity ratios observed in the gaseous halo of the Milky Way and other galaxies are inconsistent with pure photoionization models. They appear to require a supplemental heating mechanism that increases the electron temperature at low densities, ne. This would imply that in addition to photoionization, which has a heating rate per unit volume proportional to n2e, there is another source of heat with a rate per unit volume proportional to a lower power of ne. One possible mechanism is the dissipation of interstellar plasma turbulence, which, according to Minter & Spangler, heats the ionized interstellar medium in the Milky Way at a rate of approximately 1x10-25ne ergs cm-3 s-1. If such a source were present, it would dominate over photoionization heating in regions where ne less, similar0.1 cm-3, producing the observed increases in the [S ii]/Halpha and [N ii]/Halpha intensity ratios at large distances from the galactic midplane as well as accounting for the constancy of [S ii]/[N ii], which is not explained by pure photoionization. Other supplemental heating sources, such as magnetic reconnection, cosmic rays, or photoelectric emission from small grains, could also account for these observations, provided they supply approximately 10-5 ergs s-1 per square centimeter of the Galactic disk to the warm ionized medium.

  2. Climate change and heat waves in Paris and London metropolitan areas

    NASA Astrophysics Data System (ADS)

    Dousset, B.

    2010-12-01

    Summer warming trends in Western and Central Europe and in Mediterranean regions are increasing the incidence, intensity, and duration of heat waves. Those extreme events are especially deadly in large cities, owing to high population densities, surface characteristics, heat island effects, anthropogenic heat and pollutants. In August 2003, a persistent anticyclone over Western Europe generated a heat wave of exceptional strength and duration with an estimated death toll of 70,000, including 4678 in the Paris region. A series of NOAA-AVHRR satellite thermal images over the Paris and London metropolitan areas, were used to analyze Land Surface Temperature (LST) and its related mortality. In the Paris region, LSTs were merged with land use and cover data to identify risk areas, and thermal indicators were produced at the addresses of ~ 500 elderly people to assess diurnal heat exposure. Results indicate: (i) contrasting night time and daytime heat island patterns related to land use and surface characteristics; (ii) the relation between night-time heat islands and heat waves intensity; (iii) the impact of elevated minimal temperatures on excess mortality, with a 0.5 °C increase doubling the risk of death, (in the temperature range of the heatwave); iv) the correlation between the spatial distribution of highest night-time LSTs and that of highest mortality ratios; and v) the significant impact of urban parks in the partitioning between latent and sensible surface heat fluxes, despite a prior warm and dry spring. Near-real time satellite monitoring of heat waves in urban areas improve our understanding of the LST processes and spatial variability, and of the related heat stress and mortality. These observations provide criteria for warning systems, contingency policies and planning, and climate adaptation and mitigation strategies.

  3. Laser heat treatment of aerosol-jet additive manufactured graphene patterns

    NASA Astrophysics Data System (ADS)

    Jabari, Elahe; Toyserkani, Ehsan

    2015-09-01

    In this article, a laser processing protocol for heat treatment of micro-scale printed graphene patterns is developed, and the results are compared with the counterpart results obtained by the conventional heat treatment process carried out in a furnace. A continuous-wave Erbium fiber laser is used to enhance electrical properties of the aerosol-jet printed graphene patterns through removing solvents and a stabilizer polymer. The laser power and the process speed are optimized to effectively treat the printed patterns without compromising the quality of the graphene flakes. Furthermore, a heat transfer model is developed and its results are utilized to optimize the laser treatment process. It is found that the laser heat treatment process with a laser speed of 0.03 mm s-1, a laser beam diameter ~50 μm, and a laser power of 10 W results in pure graphene patterns with no excessive components. The ratio of D to G bands ({{I}\\text{D}}/{{I}\\text{G}}) in Raman graph of the laser treated pure graphene, which is an indicator of the level of the active defects in graphene structures, is 0.52. The laser treated pure graphene structures also have a C/O ratio and an electrical resistivity of ~4.5 and 0.022 Ω cm, respectively. These values are fairly comparable with the results of samples treated in a furnace. The results suggest that the laser processing has the capability of removing stabilizer polymers and solvents through a localized moving heat source, which is preferable for flexible electronics with low working temperature substrates.

  4. Heat conduction in double-walled carbon nanotubes with intertube additional carbon atoms.

    PubMed

    Cui, Liu; Feng, Yanhui; Tan, Peng; Zhang, Xinxin

    2015-07-01

    Heat conduction of double-walled carbon nanotubes (DWCNTs) with intertube additional carbon atoms was investigated for the first time using a molecular dynamics method. By analyzing the phonon vibrational density of states (VDOS), we revealed that the intertube additional atoms weak the heat conduction along the tube axis. Moreover, the phonon participation ratio (PR) demonstrates that the heat transfer in DWCNTs is dominated by low frequency modes. The added atoms cause the mode weight factor (MWF) of the outer tube to decrease and that of the inner tube to increase, which implies a lower thermal conductivity. The effects of temperature, tube length, and the number and distribution of added atoms were studied. Furthermore, an orthogonal array testing strategy was designed to identify the most important structural factor. It is indicated that the tendencies of thermal conductivity of DWCNTs with added atoms change with temperature and length are similar to bare ones. In addition, thermal conductivity decreases with the increasing number of added atoms, more evidently for atom addition concentrated at some cross-sections rather than uniform addition along the tube length. Simultaneously, the number of added atoms at each cross-section has a considerably more remarkable impact, compared to the tube length and the density of chosen cross-sections to add atoms.

  5. Solar assisted heat pumps: A possible wave of the future

    NASA Technical Reports Server (NTRS)

    Smetana, F. O.

    1976-01-01

    With the higher costs of electric power and the widespread interest to use solar energy to reduce the national dependence on fossil fuels, heat pumps are examined to determine their suitability for use with solar energy systems.

  6. Simulation of MLI concerning the influence of an additional heat load on intermediate layers

    SciTech Connect

    Funke, Thomas; Golle, Steffen; Haberstroh, Christoph

    2014-01-29

    Multilayer insulation (MLI) is commonly used in most cryogenic devices such as LHe cryostats or storage vessels. Numerical and experimental studies of such insulation systems are known from literature. The temperature distribution of intermediate layers has been investigated as well. Experiments using temperature sensors, for example thermocouples, to determine the temperature of intermediate layers had been described. Naturally such wiring causes additional heat load on the respective layer and influences the equilibrium temperature. A mathematical model of heat transfer through MLI has been developed to investigate the temperature distribution across the MLI layers. The model comprises a combination of radiation, residual gas conduction and conductive heat flux. An analysis for variable cold and warm boundary temperatures and various residual gases and pressures is carried out. In addition to the model an experimental test rig will be built for the verification of the model. The paper presents the influence of an additional heat load on an intermediate layer on the temperature distribution and on the overall thermal performance of MLI.

  7. Effect of ionic additive on pool boiling critical heat flux of titania/water nanofluids

    NASA Astrophysics Data System (ADS)

    Jung, Jung-Yeul; Kim, Hyungdae; Kim, Moo Hwan

    2013-01-01

    TiO2/water nanofluids were prepared and tested to investigate the effects of an ionic additive (i.e., nitric acid in this study) on the critical heat flux (CHF) behavior in pool boiling. Experimental results showed that the ionic additive improved the dispersion stability but reduced the CHF increase in the nanofluid. The additive affected the self-assembled nanoparticle structures formed on the heater surfaces by creating a more uniform and smoother structure, thus diminishing the CHF enhancement in nanofluids.

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

    NASA Astrophysics Data System (ADS)

    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

  9. Heat-transfer measurements and computations of swept-shock-wave boundary-layer interactions

    NASA Technical Reports Server (NTRS)

    Lee, Y.; Settles, G. S.; Horstman, C. C.

    1994-01-01

    An experimental and computational research program providing new knowledge of the heat transfer in swept-shock-wave/boundary-layer interactions is described. An equilibrium turbulent boundary layer on a flat plate is subjected to impingement by a swept planar shock wave generated by a sharp fin. Five different interactions with fin angles ranging from 10 to 20 deg at freestream Mach numbers of 3 and 4 produce a variety of interaction strengths ranging from weak to very strong. A foil heater generates a uniform heat flux over the flat plate surface, and miniature thin-film-resistance sensors are used to measure the local surface temperature. The heat convection equation is then solved for the heat transfer distribution within an interaction, yielding an uncertainty of about +/- 10%. These data are compared with numerical Navier-Stokes solutions that employ a k-epsilon turbulence model. A simple peak heat transfer correlation for fin interactions is suggested.

  10. Experimental Study of Shock Wave Interference Heating on a Cylindrical Leading Edge. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Wieting, Allan R.

    1987-01-01

    An experimental study of shock wave interference heating on a cylindrical leading edge representative of the cowl of a rectangular hypersonic engine inlet at Mach numbers of 6.3, 6.5, and 8.0 is presented. Stream Reynolds numbers ranged from 0.5 x 106 to 4.9 x 106 per ft. and stream total temperature ranged from 2100 to 3400 R. The model consisted of a 3" dia. cylinder and a shock generation wedge articulated to angles of 10, 12.5, and 15 deg. A fundamental understanding was obtained of the fluid mechanics of shock wave interference induced flow impingement on a cylindrical leading edge and the attendant surface pressure and heat flux distributions. The first detailed heat transfer rate and pressure distributions for two dimensional shock wave interference on a cylinder was provided along with insight into the effects of specific heat variation with temperature on the phenomena. Results show that the flow around a body in hypersonic flow is altered significantly by the shock wave interference pattern that is created by an oblique shock wave from an external source intersecting the bow shock wave produced in front of the body.

  11. Influence of Alumina Addition to Aluminum Fins for Compact Heat Exchangers Produced by Cold Spray Additive Manufacturing

    NASA Astrophysics Data System (ADS)

    Farjam, Aslan; Cormier, Yannick; Dupuis, Philippe; Jodoin, Bertrand; Corbeil, Antoine

    2015-10-01

    In this work, aluminum and aluminum-alumina powder mixtures were used to produce pyramidal fin arrays on aluminum substrates using cold spray as an additive manufacturing process. Using aluminum-alumina mixtures instead of pure aluminum powder could be seen as a cost-effective measure, preventing nozzle clogging or the need to use expensive polymer nozzles that wear out rapidly during cold spray. The fin geometries that were produced were observed using a 3D digital microscope to determine the flow passages width and fins' geometric details. Heat transfer and pressure drop tests were carried out using different ranges of appropriate Reynolds numbers for the sought commercial application to compare each fin array and determine the effect of alumina content. It was found that the presence of alumina reduces the fins' performance when compared to pure aluminum fins but that they were still outperforming traditional fins. Numerical simulations were performed to model the fin arrays and were used to predict the pressure loss in the fin array and compare these results with experimental values. The numerical model opens up new avenues in predicting different applicable operating conditions and other possible fin shapes using the same fin composition, instead of performing costly and time-consuming experiments.

  12. Future changes in Central Europe heat waves expected to mostly follow summer mean warming

    NASA Astrophysics Data System (ADS)

    Ballester, Joan; Rodó, Xavier; Giorgi, Filippo

    2010-12-01

    Daily output from the PRUDENCE ensemble of regional climate simulations for the end of the twentieth and twenty-first centuries over Europe is used to show that the increasing intensity of the most damaging summer heat waves over Central Europe is mostly due to higher base summer temperatures. In this context, base temperature is defined as the mean of the seasonal cycle component for those calendar days when regional heat waves occur and is close, albeit not identical, to the mean temperature for July-August. Although 36-47% of future Central Europe July and August days at the end of the twenty-first century are projected to be extreme according to the present day climatology, specific changes in deseasonalized heat wave anomalies are projected to be relatively small. Instead, changes in summer base temperatures appear much larger, clearly identifiable and of the same order of magnitude as changes in the whole magnitude of heat waves. Our results bear important consequences for the predictability of central European heat wave intensity under global warming conditions.

  13. Mapping Mortality and Geophysical Features During a Heat Wave in Los Angeles County, California

    NASA Astrophysics Data System (ADS)

    Joe, L.

    2011-12-01

    With climate change, heat waves are predicted to increase in intensity and duration, particularly in areas where they have occurred previously. Human mortality increases during heat waves, and that increase may vary by community due to a variety of factors including differing geophysical and built environment features. In July 2006, California experienced a statewide heat wave that was unprecedented in duration, lasting 10 days in much of the state, and longer in some areas. To explore heat wave health impacts by community, we focused on Los Angeles County, selected for its urban density and diverse social and geographic landscapes. We calculated the ratio of deaths during the heat wave period (July 15 - Aug 1) to deaths in reference days from the non-heat wave period in the same summer. The raw and empirical Bayes smoothed rate ratios were mapped by census tract (average population size approximately 5000). We then used spatial scanning procedures to identify census tract clusters of high and low mortality. Onto the heat mortality maps, we overlaid such geographic and built environment characteristics as elevation, recordings from temperature monitors, building climate zone boundaries, and air conditioning use. In this presentation, we will discuss the potential relationship between mortality and geophysical and built environment features. In the future, we will expand this analysis statewide and share our findings with local stakeholders to explore factors which may make their communities more resilient (low health impact) or vulnerable (high health impact). Ultimately, knowledge of vulnerability and resiliency factors may inform future applied research and climate change mitigation and adaptation strategies. Authors: Lauren Joe, Daniel Smith, Svetlana Smorodinksy, Sumi Hoshiko, Martha Harnly Environmental Health Investigations Branch, California Department of Public Health

  14. HEATING OF THE SOLAR CHROMOSPHERE AND CORONA BY ALFVEN WAVE TURBULENCE

    SciTech Connect

    Van Ballegooijen, A. A.; Cranmer, S. R.; DeLuca, E. E.; Asgari-Targhi, M.

    2011-07-20

    A three-dimensional magnetohydrodynamic (MHD) model for the propagation and dissipation of Alfven waves in a coronal loop is developed. The model includes the lower atmospheres at the two ends of the loop. The waves originate on small spatial scales (less than 100 km) inside the kilogauss flux elements in the photosphere. The model describes the nonlinear interactions between Alfven waves using the reduced MHD approximation. The increase of Alfven speed with height in the chromosphere and transition region (TR) causes strong wave reflection, which leads to counter-propagating waves and turbulence in the photospheric and chromospheric parts of the flux tube. Part of the wave energy is transmitted through the TR and produces turbulence in the corona. We find that the hot coronal loops typically found in active regions can be explained in terms of Alfven wave turbulence, provided that the small-scale footpoint motions have velocities of 1-2 km s{sup -1} and timescales of 60-200 s. The heating rate per unit volume in the chromosphere is two to three orders of magnitude larger than that in the corona. We construct a series of models with different values of the model parameters, and find that the coronal heating rate increases with coronal field strength and decreases with loop length. We conclude that coronal loops and the underlying chromosphere may both be heated by Alfvenic turbulence.

  15. A theoretical study of wave dispersion and thermal conduction for HMX/additive interfaces

    NASA Astrophysics Data System (ADS)

    Long, Yao; Chen, Jun

    2014-04-01

    The wave dispersion rule for non-uniform material is useful for ultrasonic inspection and engine life prediction, and also is key in achieving an understanding of the energy dissipation and thermal conduction properties of solid material. On the basis of linear response theory and molecular dynamics, we derive a set of formulas for calculating the wave dispersion rate of interface systems, and study four kinds of interfaces inside plastic bonded explosives: HMX/{HMX, TATB, F2312, F2313}. (HMX: octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine; TATB: 1,3,5-triamino-2,4,6-trinitrobenzene; F2312, F2313: fluoropolymers). The wave dispersion rate is obtained over a wide frequency range from kHz to PHz. We find that at low frequency, the rate is proportional to the square of the frequency, and at high frequency, the rate couples with the molecular vibration modes at the interface. By using the results, the thermal conductivities of HMX/additive interfaces are derived, and a physical model is built for describing the total thermal conductivity of mixture explosives, including HMX multi-particle systems and {TATB, F2312, F2313}-coated HMX.

  16. Proton Heating by Cyclotron Waves in the Presence of a Finite Source and a Sink

    NASA Astrophysics Data System (ADS)

    Kim, S.; Yoon, P. H.; Choe, G.

    2012-12-01

    One of the outstanding problems in the study of solar wind is the acceleration of protons and heavy ions. The preferential heating of these ions in the direction perpendicular to the ambient magnetic field is interpreted as the resonant heating by cyclotron waves. The present paper investigates the resonant cyclotron heating of the solar wind ions by quasilinear theoretical formalism. The major focus is on the role of source and sink terms associated with the Alfven-cyclotron waves. If one considers low-frequency Alfvenic waves as the wave source, then the resulting cyclotron heating is extremely small [Yoon & Fang 2009, Rha et al., 2011, Moya et al., 2011]. However, with a finite source term an appreciable heating can result [Yoon & Fang 2009]. The purpose of the present paper is to investigate the problem of Alfvenic turbulent heating by cyclotron resonance with a continuous source of Alfvenic turbulence as well as a sink term. We also discuss the role of nonlinear mode coupling as well as the effects of spatial inhomogeneity.

  17. Impact of Heat Waves on Urban Areas in the North Eastern United States

    NASA Astrophysics Data System (ADS)

    Ramamurthy, P.; Li, D.; Bou-Zeid, E.

    2014-12-01

    We utilize high-resolution numerical simulations to understand the interaction between heat waves and urban heat islands in the North Eastern United States. Urban areas, due to their dense built-surface cover that efficiently stores and dissipate heat and reduced evapotranspiration, experience elevated near surface temperatures compared to surrounding rural areas. This difference between urban and nearby rural temperature is commonly known as the Urban Heat island Intensity (UHI), which amplifies the effects of heat waves in cities. In this work, the Weather Research and Forecasting (WRF) model is significantly modified in two major ways to study two heat wave episodes in the North East during the Summer of 2006. First, the single layer urban canopy model in WRF is replaced by the Princeton Urban Canopy Model (PUCM), which includes representation for sub-facet scale heterogeneity. Second, the dominant land use approach used in the default land surface scheme is substituted with a tile-based approach to suitably capture the variability in the urban surface cover. Our preliminary results show that the magnitude of the UHI increased in New York City by more than 1°C during both the nighttime and daytime periods during the heat wave episodes. In Baltimore and Washington D. C, while the UHI increased during the nighttime period, the daytime UHI was mostly unchanged. This ongoing work will further focus on the role played by moisture availability, available energy, wind direction and magnitude and urban characteristics like population density and urban cover in modulating the UHI during these intense heat wave periods.

  18. Stability analysis of an interactive system of wave equation and heat equation with memory

    NASA Astrophysics Data System (ADS)

    Zhang, Qiong

    2014-10-01

    This paper is devoted to the stability analysis of an interaction system comprised of a wave equation and a heat equation with memory, where the hereditary heat conduction is due to Gurtin-Pipkin law or Coleman-Gurtin law. First, we show the strong asymptotic stability of solutions to this system. Then, the exponential stability of the interaction system is obtained when the hereditary heat conduction is of Gurtin-Pipkin type. Further, we show the lack of uniform decay of the interaction system when the heat conduction law is of Coleman-Gurtin type.

  19. Severe heat waves in Southern Australia: synoptic climatology and large scale connections

    NASA Astrophysics Data System (ADS)

    Pezza, Alexandre Bernardes; van Rensch, Peter; Cai, Wenju

    2012-01-01

    This paper brings a new perspective on the large scale dynamics of severe heat wave (HW) events that commonly affect southern Australia. Through an automatic tracking scheme, the cyclones and anticyclones associated with HWs affecting Melbourne, Adelaide and Perth are tracked at both the surface and upper levels, producing for the first time a synoptic climatology that reveals the broader connections associated with these extreme phenomena. The results show that a couplet (or pressure dipole) formed by transient cyclones and anticyclones can reinforce the HW similarly to what is observed in cold surges (CS), with an obvious opposite polarity. Our results show that there is a large degree of mobility in the synoptic signature associated with the passage of the upper level ridges before they reach Australia and the blocking is established, with HW-associated surface anticyclones often initiating over the west Indian Ocean and decaying in the eastern Pacific. In contrast to this result the 500 hPa anticyclone tracks show a very small degree of mobility, responding to the dominance of the upper level blocking ridge. An important feature of HWs is that most of the cyclones are formed inland in association with heat troughs, while in CS the cyclones are typically maritime (often explosive), associated with a strong cold front. Hence the influence of the cyclone is indirect, contributing to reinforce the blocking ridge through hot and dry advection on the ridge's western flank. Additional insights are drawn for the record Adelaide case of March 2008 with fifteen consecutive days above 35°C breaking the previous record by 7 days. Sea surface temperatures suggest a significant air-sea interaction mechanism, with a broad increase in the meridional temperature gradient over the Indian Ocean amplifying the upstream Rossby waves that can trigger HW events. A robust cooling of the waters close to the Australian coast also contributes to the maintenance of the blocking highs

  20. Additive Manufacturing for Cost Efficient Production of Compact Ceramic Heat Exchangers and Recuperators

    SciTech Connect

    Shulman, Holly; Ross, Nicole

    2015-10-30

    An additive manufacture technique known as laminated object manufacturing (LOM) was used to fabricate compact ceramic heat exchanger prototypes. LOM uses precision CO2 laser cutting of ceramic green tapes, which are then precision stacked to build a 3D object with fine internal features. Modeling was used to develop prototype designs and predict the thermal response, stress, and efficiency in the ceramic heat exchangers. Build testing and materials analyses were used to provide feedback for the design selection. During this development process, laminated object manufacturing protocols were established. This included laser optimization, strategies for fine feature integrity, lamination fluid control, green handling, and firing profile. Three full size prototypes were fabricated using two different designs. One prototype was selected for performance testing. During testing, cross talk leakage prevented the application of a high pressure differential, however, the prototype was successful at withstanding the high temperature operating conditions (1300 °F). In addition, analysis showed that the bulk of the part did not have cracks or leakage issues. This led to the development of a module method for next generation LOM heat exchangers. A scale-up cost analysis showed that given a purpose built LOM system, these ceramic heat exchangers would be affordable for the applications.

  1. Modeled heating and surface erosion comparing motile (gas borne) and stationary (surface coating) inert particle additives

    SciTech Connect

    Buckingham, A.C.; Siekhaus, W.J.

    1982-09-27

    The unsteady, non-similar, chemically reactive, turbulent boundary layer equations are modified for gas plus dispersed solid particle mixtures, for gas phase turbulent combustion reactions and for heterogeneous gas-solid surface erosive reactions. The exterior (ballistic core) edge boundary conditions for the solutions are modified to include dispersed particle influences on core propellant combustion-generated turbulence levels, combustion reactants and products, and reaction-induced, non-isentropic mixture states. The wall surface (in this study it is always steel) is considered either bare or coated with a fixed particle coating which is conceptually non-reactive, insulative, and non-ablative. Two families of solutions are compared. These correspond to: (1) consideration of gas-borne, free-slip, almost spontaneously mobile (motile) solid particle additives which influence the turbulent heat transfer at the uncoated steel surface and, in contrast, (2) consideration of particle-free, gas phase turbulent heat transfer to the insulated surface coated by stationary particles. Significant differences in erosive heat transfer are found in comparing the two families of solutions over a substantial range of interior ballistic flow conditions. The most effective influences on reducing erosive heat transfer appear to favor mobile, gas-borne particle additives.

  2. Model Scramjet Inlet Unstart Induced by Mass Addition and Heat Release

    NASA Astrophysics Data System (ADS)

    Im, Seong-Kyun; Baccarella, Damiano; McGann, Brendan; Liu, Qili; Wermer, Lydiy; Do, Hyungrok

    2015-11-01

    The inlet unstart phenomena in a model scramjet are investigated at an arc-heated hypersonic wind tunnel. The unstart induced by nitrogen or ethylene jets at low or high enthalpy Mach 4.5 freestream flow conditions are compared. The jet injection pressurizes the downstream flow by mass addition and flow blockage. In case of the ethylene jet injection, heat release from combustion increases the backpressure further. Time-resolved schlieren imaging is performed at the jet and the lip of the model inlet to visualize the flow features during unstart. High frequency pressure measurements are used to provide information on pressure fluctuation at the scramjet wall. In both of the mass and heat release driven unstart cases, it is observed that there are similar flow transient and quasi-steady behaviors of unstart shockwave system during the unstart processes. Combustion driven unstart induces severe oscillatory flow motions of the jet and the unstart shock at the lip of the scramjet inlet after the completion of the unstart process, while the unstarted flow induced by solely mass addition remains relatively steady. The discrepancies between the processes of mass and heat release driven unstart are explained by flow choking mechanism.

  3. A STUDY OF ALFVÉN WAVE PROPAGATION AND HEATING THE CHROMOSPHERE

    SciTech Connect

    Tu, Jiannan; Song, Paul

    2013-11-01

    Alfvén wave propagation, reflection, and heating of the chromosphere are studied for a one-dimensional solar atmosphere by self-consistently solving plasma, neutral fluid, and Maxwell's equations with incorporation of the Hall effect and strong electron-neutral, electron-ion, and ion-neutral collisions. We have developed a numerical model based on an implicit backward difference formula of second-order accuracy both in time and space to solve stiff governing equations resulting from strong inter-species collisions. A non-reflecting boundary condition is applied to the top boundary so that the wave reflection within the simulation domain can be unambiguously determined. It is shown that due to the density gradient the Alfvén waves are partially reflected throughout the chromosphere and more strongly at higher altitudes with the strongest reflection at the transition region. The waves are damped in the lower chromosphere dominantly through Joule dissipation, producing heating strong enough to balance the radiative loss for the quiet chromosphere without invoking anomalous processes or turbulences. The heating rates are larger for weaker background magnetic fields below ∼500 km with higher-frequency waves subject to heavier damping. There is an upper cutoff frequency, depending on the background magnetic field, above which the waves are completely damped. At the frequencies below which the waves are not strongly damped, the interaction of reflected waves with the upward propagating waves produces power at their double frequencies, which leads to more damping. The wave energy flux transmitted to the corona is one order of magnitude smaller than that of the driving source.

  4. A Study of Alfvén Wave Propagation and Heating the Chromosphere

    NASA Astrophysics Data System (ADS)

    Tu, Jiannan; Song, Paul

    2013-11-01

    Alfvén wave propagation, reflection, and heating of the chromosphere are studied for a one-dimensional solar atmosphere by self-consistently solving plasma, neutral fluid, and Maxwell's equations with incorporation of the Hall effect and strong electron-neutral, electron-ion, and ion-neutral collisions. We have developed a numerical model based on an implicit backward difference formula of second-order accuracy both in time and space to solve stiff governing equations resulting from strong inter-species collisions. A non-reflecting boundary condition is applied to the top boundary so that the wave reflection within the simulation domain can be unambiguously determined. It is shown that due to the density gradient the Alfvén waves are partially reflected throughout the chromosphere and more strongly at higher altitudes with the strongest reflection at the transition region. The waves are damped in the lower chromosphere dominantly through Joule dissipation, producing heating strong enough to balance the radiative loss for the quiet chromosphere without invoking anomalous processes or turbulences. The heating rates are larger for weaker background magnetic fields below ~500 km with higher-frequency waves subject to heavier damping. There is an upper cutoff frequency, depending on the background magnetic field, above which the waves are completely damped. At the frequencies below which the waves are not strongly damped, the interaction of reflected waves with the upward propagating waves produces power at their double frequencies, which leads to more damping. The wave energy flux transmitted to the corona is one order of magnitude smaller than that of the driving source.

  5. On The Role of MHD Waves in Heating Localised Magnetic Structures

    NASA Astrophysics Data System (ADS)

    Erdélyi, R.; Nelson, C. J.

    2016-04-01

    Satellite and ground-based observations from e.g. SOHO, TRACE, STEREO, Hinode, SDO and IRIS to DST/ROSA, IBIS, CoMP, STT/CRISP have provided a wealth of evidence of waves and oscillations present in a wide range of spatial scales of the magnetised solar atmosphere. Our understanding about localised solar structures has been considerably changed in light of these high spatial and time resolution observations. However, MHD waves not only enable us to perform sub-resolution magneto-seismology of magnetic waveguides but are also potential candidates to carry and damp the necessary non-thermal energy in these localised waveguides. First, we will briefly outline the basic recent developments in MHD wave theory focussing on linear waves. Next, we discuss the role of the most frequently studied wave classes, including the Alfven, and magneto-acoustic kink and sausage waves. The current theoretical (and often difficult) interpretations of the detected solar atmospheric wave and oscillatory phenomena within the framework of MHD will be shown. Last, the latest reported observational findings of potential MHD wave flux, in terms of localised plasma heating, in the solar atmosphere is discussed, bringing us closer to solve the coronal heating problem.

  6. Role of 3d-dispersive Alfven waves in coronal heating

    NASA Astrophysics Data System (ADS)

    Sharma, R. P.; Yadav, N.; Pathak, N.

    2014-05-01

    Coronal heating is one of the unresolved puzzles in solar physics from decades. In the present paper we have investigated the dynamics of vortices to apprehend coronal heating problem. A three dimensional (3d) model has been developed to study propagation of dispersive Alfvén waves (DAWs) in presence of ion acoustic waves which results in excitation of DAW and evolution of vortices. Taking ponderomotive nonlinearity into account, development of these vortices has been studied. There are observations of such vortices in the chromosphere, transition region and also in the lower solar corona. These structures may play an important role in transferring energy from lower solar atmosphere to corona and result in coronal heating. Nonlinear interaction of these waves is studied in view of recent simulation work and observations of giant magnetic tornadoes in solar corona and lower atmosphere of sun by solar dynamical observatory (SDO).

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

    SciTech Connect

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

    2009-01-01

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

  8. Variation of wave velocity and porosity of sandstone after high temperature heating

    NASA Astrophysics Data System (ADS)

    Sun, Qiang; Zhang, ·Weiqiang; Su, Tianming; Zhu, Shuyun

    2016-05-01

    This paper reports the variations of mass, porosity, and wave velocity of sandstone after high temperature heating. The range of temperature to which the sandstone specimens have been exposed is 25-850°C, in a heating furnace. It has been shown that below 300°C, porosity and wave velocity change very little. Above 300°C, there is a rapid increase in porosity, but the wave velocity decreases significantly. The results of thermo gravimetric analysis (TGA), differential scanning calorimetry (DSC) and mercury intrusion porosimetry (MIP) suggest that a series of changes occurred between 400 and 600°C in sandstone could be responsible for the different patterns of variation in porosity and wave velocity.

  9. The possible role of MHD waves in heating the solar corona

    NASA Technical Reports Server (NTRS)

    Porter, Lisa J.; Klimchuk, James A.; Sturrock, Peter A.

    1994-01-01

    The possible role of waves in the heating of the solar corona has been investigated. A general dispersion relation has been derived for waves propagating in a homogeneous plasma subject to dissipation by viscosity and thermal conduction. The dissipation mechanisms have been incorporated self-consistently into the equations, and no assumptions about the strength of the damping have been made. Solutions of the sixth-order dispersion relation provide information on how the damping of both slow and fast mode waves depends upon the plasma density, temperature, field strength, and angle of propagation relative to the background magnetic field. We provide a detailed comparison to the standard approach, which is to solve for the wave quantities in the absence of dissipation and then to use these quantities in expressions for the heating due to viscosity and thermal conduction.

  10. On cyclotron wave heating and acceleration of solar wind ions in the outer corona

    NASA Astrophysics Data System (ADS)

    Tu, C.-Y.; Marsch, E.

    2001-05-01

    The preferential heating and acceleration of O+5 ions, as observed by Ultraviolet Coronagraph Spectrometer (UVCS) on Solar and Heliospheric Observatory (SOHO) [Kohl et al., 1998] in the solar coronal holes have been interpreted and modeled by invoking wave-particle cyclotron resonance [Cranmer et al., 1999a, 1999b]. However, in the model of Cranmer et al. [1999a, 1999b] and in other subsequent models the assumption of a rigid slope of the wave spectrum was made in calculating the wave energy absortion by the different ion species. In the present paper it is shown that a self-consistent treatment of the wave damping and absorption is necessary and leads to substantially different results. On the basis of quasi-linear theory, the interaction between the ions and the ion-cyclotron waves [Marsch et al., 1982a; Marsch, 1998] is studied. The total energy conservation equation, including the kinetic energy of the resonant particles and the wave energy, is derived and discussed in detail. The spectral evolution equation for cyclotron waves, when being controlled by the wave growth/damping rate and WKB effects, is solved self-consistently together with the full set of anisotropic multifluid equations for the ions including the cyclotron-resonance wave heating and acceleration rates. From the numerical results we reach the following conclusions: (1) It is physically questionable to use a spectrum with a fixed spectral slope near the cyclotron resonance when one calculates the partition of wave energy among the different ionic species and the kinetic degrees of freedom parallel and perpendicular to the magnetic field. This assumption neglects the important effects of wave absorption and the concurrent reshaping of the wave spectrum, and thus leads in the dissipation domain to extremely low amplitudes of the waves and to difficulties in supplying enough energy to balance the wave absorption at the cyclotron resonances. (2) If the spectrum is allowed to evolve self

  11. A review on augmentation of heat transfer in boiling using surfactants/additives

    NASA Astrophysics Data System (ADS)

    Acharya, Anil; Pise, Ashok

    2016-09-01

    Studies of heat transfer enhancement in boiling under various conditions and configurations have given different results. Understanding the boiling behaviour from these studies, literature is reviewed in terms of surface texture, heater geometry and orientation, experimental and numerical studies in presence of surfactant/additives. After understanding different behaviour in boiling, the effect of environment friendly surfactant is studied through literature review. Benchmarking of experimental procedure is done by experimenting and comparing some surfactants studied in literature.

  12. Farley Buneman wave heating: Confirming heuristics with radar observations

    NASA Astrophysics Data System (ADS)

    Miceli, R. J.; Hysell, D. L.; Munk, J.; Huba, J. D.

    2013-12-01

    Combined observations from the Poker Flat incoherent scatter radar (PFISR) and a 30 MHz coherent scatter radar in Homer, Alaska were made during geomagnetic storms in November 2012 and March 2013. Enhanced electron temperature and density in the E region were measured by the PFISR and strong echoes from field aligned irregularities were measured by the coherent scatter radar. We compare these observations with a heuristic model of Farley Buneman waves based on the formulations of Milikh and Dimant (2002) and the SAMI2 global model of the ionosphere. The model predicts phase speed and magnetic aspect width profiles, as well as profiles of ionospheric state variables as functions of the convective electric field. By accounting for the thickness of the region where Farley Buneman waves exist and weighting the profiles accordingly, the model is capable of estimating the phase velocity and magnetic aspect width that would be observed by a coherent scatter radar. We then use the comparison to assess the empirical relationships of coherent scatter radar observations of Farley Buneman waves.

  13. Parametric instabilities in the fast-wave heating of tokamaks

    SciTech Connect

    Tripathi, V.K.

    1984-12-01

    A high-power whistler wave launched into a tokomak is susceptible to resonant decay into ion-cyclotron and lower-hybrid waves when the lower-hybrid resonance layer ..omega../sub lh/ = ..omega../sub 0/ exists in the outer region of the plasma x/sup 2//a/sup 2/> or approx. =0.6, where ..omega../sub 0/ is the frequency of the whistler, ..omega../sub lh/ is the lower-hybrid frequency, x is the distance away from the center of the plasma, and a is the minor radius. For Princeton Large Torus parameters, this requires a line average density n> or approx. =6 x 10/sup 13/ cm/sup -3/ when the whistler frequency ..omega../sub 0/approx. =800 MHz and the threshold pump power for the onset of the instability is 100 kW. The threshold power is determined by the convection losses and it increases nonlinearly with the temperature and very rapidly with decreasing density. The parametric instability would tend to deposit the momentum and energy of the pump wave in the outer region of the plasma.

  14. Parametric instabilities in the fast-wave heating of tokamaks

    NASA Astrophysics Data System (ADS)

    Tripathi, V. K.

    1984-12-01

    A high-power whistler wave launched into a tokomak is susceptible to resonant decay into ion-cyclotron and lower-hybrid waves when the lower-hybrid resonance layer ωlh=ω0 exists in the outer region of the plasma x2/a2≳0.6, where ω0 is the frequency of the whistler, ωlh is the lower-hybrid frequency, x is the distance away from the center of the plasma, and a is the minor radius. For Princeton Large Torus parameters, this requires a line average density n≳6×1013 cm-3 when the whistler frequency ω0≂800 MHz and the threshold pump power for the onset of the instability is 100 kW. The threshold power is determined by the convection losses and it increases nonlinearly with the temperature and very rapidly with decreasing density. The parametric instability would tend to deposit the momentum and energy of the pump wave in the outer region of the plasma.

  15. KINETIC INSTABILITY OF DRIFT-ALFVEN WAVES IN SOLAR CORONA AND STOCHASTIC HEATING

    SciTech Connect

    Vranjes, J.; Poedts, S. E-mail: Stefaan.Poedts@wis.kuleuven.b

    2010-08-20

    The solar atmosphere is structured and inhomogeneous, both horizontally and vertically. The omnipresence of coronal magnetic loops implies gradients of the equilibrium plasma quantities such as the density, magnetic field, and temperature. These gradients are responsible for the excitation of drift waves that grow both within the two-component fluid description (both in the presence of collisions and without it) and within the two-component kinetic descriptions (due to purely kinetic effects). In this work, the effects of the density gradient in the direction perpendicular to the magnetic field vector are investigated within the kinetic theory, in both electrostatic (ES) and electromagnetic (EM) regimes. The EM regime implies the coupling of the gradient-driven drift wave with the Alfven wave. The growth rates for the two cases are calculated and compared. It is found that, in general, the ES regime is characterized by stronger growth rates, as compared with the EM perturbations. Also discussed is the stochastic heating associated with the drift wave. The released amount of energy density due to this heating should be more dependent on the magnitude of the background magnetic field than on the coupling of the drift and Alfven waves. The stochastic heating is expected to be much higher in regions with a stronger magnetic field. On the whole, the energy release rate caused by the stochastic heating can be several orders of magnitude above the value presently accepted as necessary for a sustainable coronal heating. The vertical stratification and the very long wavelengths along the magnetic loops imply that a drift-Alfven wave, propagating as a twisted structure along the loop, in fact occupies regions with different plasma-{beta} and, therefore, may have different (EM-ES) properties, resulting in different heating rates within just one or two wavelengths.

  16. Are heat waves susceptible to mitigate the expansion of a species progressing with global warming?

    PubMed

    Robinet, Christelle; Rousselet, Jérôme; Pineau, Patrick; Miard, Florie; Roques, Alain

    2013-09-01

    A number of organisms, especially insects, are extending their range in response of the increasing trend of warmer temperatures. However, the effects of more frequent climatic anomalies on these species are not clearly known. The pine processionary moth, Thaumetopoea pityocampa, is a forest pest that is currently extending its geographical distribution in Europe in response to climate warming. However, its population density largely decreased in its northern expansion range (near Paris, France) the year following the 2003 heat wave. In this study, we tested whether the 2003 heat wave could have killed a large part of egg masses. First, the local heat wave intensity was determined. Then, an outdoor experiment was conducted to measure the deviation between the temperatures recorded by weather stations and those observed within sun-exposed egg masses. A second experiment was conducted under laboratory conditions to simulate heat wave conditions (with night/day temperatures of 20/32°C and 20/40°C compared to the control treatment 13/20°C) and measure the potential effects of this heat wave on egg masses. No effects were noticed on egg development. Then, larvae hatched from these egg masses were reared under mild conditions until the third instar and no delayed effects on the development of larvae were found. Instead of eggs, the 2003 heat wave had probably affected directly or indirectly the young larvae that were already hatched when it occurred. Our results suggest that the effects of extreme climatic anomalies occurring over narrow time windows are difficult to determine because they strongly depend on the life stage of the species exposed to these anomalies. However, these effects could potentially reduce or enhance the average warming effects. As extreme weather conditions are predicted to become more frequent in the future, it is necessary to disentangle the effects of the warming trend from the effects of climatic anomalies when predicting the response of a

  17. Are heat waves susceptible to mitigate the expansion of a species progressing with global warming?

    PubMed Central

    Robinet, Christelle; Rousselet, Jérôme; Pineau, Patrick; Miard, Florie; Roques, Alain

    2013-01-01

    A number of organisms, especially insects, are extending their range in response of the increasing trend of warmer temperatures. However, the effects of more frequent climatic anomalies on these species are not clearly known. The pine processionary moth, Thaumetopoea pityocampa, is a forest pest that is currently extending its geographical distribution in Europe in response to climate warming. However, its population density largely decreased in its northern expansion range (near Paris, France) the year following the 2003 heat wave. In this study, we tested whether the 2003 heat wave could have killed a large part of egg masses. First, the local heat wave intensity was determined. Then, an outdoor experiment was conducted to measure the deviation between the temperatures recorded by weather stations and those observed within sun-exposed egg masses. A second experiment was conducted under laboratory conditions to simulate heat wave conditions (with night/day temperatures of 20/32°C and 20/40°C compared to the control treatment 13/20°C) and measure the potential effects of this heat wave on egg masses. No effects were noticed on egg development. Then, larvae hatched from these egg masses were reared under mild conditions until the third instar and no delayed effects on the development of larvae were found. Instead of eggs, the 2003 heat wave had probably affected directly or indirectly the young larvae that were already hatched when it occurred. Our results suggest that the effects of extreme climatic anomalies occurring over narrow time windows are difficult to determine because they strongly depend on the life stage of the species exposed to these anomalies. However, these effects could potentially reduce or enhance the average warming effects. As extreme weather conditions are predicted to become more frequent in the future, it is necessary to disentangle the effects of the warming trend from the effects of climatic anomalies when predicting the response of a

  18. The effects of latent heat release on the waves with Ekman pumping

    NASA Technical Reports Server (NTRS)

    Tang, C. M.

    1984-01-01

    The problem of the effects of the latent heat release on the waves with both upper and lower boundary frictional effects is investigated. The influence of the vertical shear of the basic wind in these models will be investigated. These investigations will shed some light on the method of solution to the problem of including the effect of Ekman pumping on the moist baroclinic waves in the model of Tang and Fichtl.

  19. Influence of heat conductivity on an intense shock wave that converges onto the center of symmetry

    NASA Astrophysics Data System (ADS)

    Makhmudov, A. A.; Popov, S. P.

    1980-04-01

    In the motion of a shock wave near the axis of a cylinder or the center of a sphere, there occurs a self-similar flow. This region is of practical importance, since many nonself-similar problems reduce to self-similar ones. In the present paper, the transformation of Guderley's (1942) self-simulating solution to an isothermal wave under the influence of nonlinear heat conductivity is analyzed numerically.

  20. Convectively Forced Gravity Waves and their Sensitivity to Heating Profile and Atmospheric Structure

    NASA Astrophysics Data System (ADS)

    Halliday, Oliver; Parker, Douglas; Griffiths, Stephen; Vosper, Simon; Stirling, Alison

    2016-04-01

    It has been known for some time that convective heating is communicated to its environment by gravity waves. Despite this, the radiation of gravity waves in macro-scale models, which are typically forced at the grid-scale by meso-scale parameterization schemes, is not well understood. We present here theoretical work directed toward improving our fundamental understanding of convectively forced gravity wave effects at the meso-scale, in order to begin to address this problem. Starting with the hydrostatic, non-rotating, 2D, Boussinesq equations in a slab geometry, we find a radiating, analytical solution to prescribed sensible heat forcing for both the vertical velocity and potential temperature response. Both Steady and pulsed heating with adjustable horizontal structure is considered. From these solutions we construct a simple model capable of interrogating the spatial and temporal sensitivity to chosen heating functions of the remote forced response in particular. By varying the assumed buoyancy frequency, the influence of the model stratosphere on the upward radiation of gravity waves, and in turn, on the tropospheric response can be understood. Further, we find that the macro-scale response to convection is highly dependent on the radiation characteristics of gravity waves, which are in turn dependent upon the temporal and spatial structure of the source, and upper boundary condition of the domain.

  1. Overview of Microwave and Millimeter Wave Testing Activities for the Inspection of the Space Shuttle SOH and Heat Tiles

    NASA Technical Reports Server (NTRS)

    Zoughi, R.

    2005-01-01

    Microwave and millimeter wave nondestructive testing and evaluation methods, have shown great potential for inspecting the Space Shuttle s external tank spray on foam insulation (SOFI) and acreage heat tiles. These methods are capable of producing high-resolution images of et interior of these structures. To this end, several different microwave and millimeter wave nondestructive testing methods have been investigated for this purpose. These methods have included near-field as well as focused approaches ranging in frequency from 10 GHz to beyond 100 GHz. Additionally, synthetic aperture focusing methods have also been developed in this regime for obtaining high-resolution images of the interior of these critical structures. These methods possess the potential for producing 3D images of these structures in a relatively short amount of time. This paper presents a summary of these activities in addition to providing examples of images produced using these diverse methods.

  2. Can the Tibetan Plateau snow cover influence the interannual variations of Eurasian heat wave frequency?

    NASA Astrophysics Data System (ADS)

    Wu, Zhiwei; Zhang, Peng; Chen, Hua; Li, Yun

    2016-06-01

    The Eurasian continent has experienced significant year-to-year variations of summer heat waves during the past decades. Several possible factors, such as ocean temperature, soil moisture, and changes in land use and greenhouse gases, have been identified in previous studies, but the mechanisms are still unclear. In this study, it is found that the Tibetan Plateau snow cover (TPSC) is closely linked to the interannual variations of summer heat waves over Eurasia. The TPSC variability explains more than 30 % of the total variances of heat wave variability in the southern Europe and northeastern Asia (SENA) region. A set of numerical experiments reveal that the reduced TPSC may induce a distinct teleconnection pattern across the Eurasian continent, with two anomalous high pressure centers in the upper troposphere over the SENA region, which may lead to a reduction of the cloud formation near the surface. The less cloud cover tends to increase the net shortwave radiation and favor a stronger surface sensible heat flux in the dry surface condition over the SENA region, resulting in a deeper, warmer and drier atmospheric boundary layer that would further inhibit the local cloud formation. Such a positive land-atmosphere feedback may dry the surface even further, heat the near-surface atmosphere and thereby intensify the local heat waves. The above dynamical processes also operate on interdecadal time scales. Given the reduction of the TPSC could become more pronounced with increasing levels of greenhouse gases in a warming climate, we infer that the TPSC may play an increasingly important role in shaping the summer heat waves over the SENA region in next decades.

  3. Particle simulation of intense electron cyclotron heating and beat-wave current drive

    SciTech Connect

    Cohen, B.I.

    1987-10-12

    High-power free-electron lasers make new methods possible for heating plasmas and driving current in toroidal plasmas with electromagnetic waves. We have undertaken particle simulation studies with one and two dimensional, relativistic particle simulation codes of intense pulsed electron cyclotron heating and beat-wave current drive. The particle simulation methods here are conventional: the algorithms are time-centered, second-order-accurate, explicit, leap-frog difference schemes. The use of conventional methods restricts the range of space and time scales to be relatively compact in the problems addressed. Nevertheless, experimentally relevant simulations have been performed. 10 refs., 2 figs.

  4. Experimental study of enhanced heat transfer by addition of CuO nanoparticle

    NASA Astrophysics Data System (ADS)

    Jesumathy, Stella; Udayakumar, M.; Suresh, S.

    2012-06-01

    An energy storage system has been designed to study the thermal characteristics of paraffin wax with an embedded nano size copper oxide (CuO) particle. This paper presents studies conducted on phase transition times, heat fraction as well as heat transfer characteristics of paraffin wax as phase change material (PCM) embedded with CuO nanoparticles. 40 nm mean size CuO particles of 2, 5 and 10% by weight were dispersed in PCM for this study. Experiments were performed on a heat exchanger with 1.5-10 l/min of heat transfer fluid (HTF) flow. Time-based variations of the temperature distributions are revealed from the results of observations of melting and solidification curves. The results strongly suggested that the thermal conductivity enhances 6, 6.7 and 7.8% in liquid state and in dynamic viscosity it enhances by 5, 14 and 30% with increasing mass fraction of the CNEPs. The thermal conductivity ratio of the composites can be augmented by a factor up to 1.3. The heat transfer coefficient during solidification increased about 78% for the maximum flow rate. The analysis of experimental results reveals that the addition of copper oxide nanoparticles to the paraffin wax enhances both the conduction and natural convection very effectively in composites and in paraffin wax. The paraffin wax-based composites have great potential for energy storage applications like industrial waste heat recovery, solar thermal applications and solar based dynamic space power generation with optimal fraction of copper oxide nanoparticles.

  5. Proton Heating in Solar Wind Compressible Turbulence with Collisions between Counter-propagating Waves

    NASA Astrophysics Data System (ADS)

    He, Jiansen; Tu, Chuanyi; Marsch, Eckart; Chen, Christopher H. K.; Wang, Linghua; Pei, Zhongtian; Zhang, Lei; Salem, Chadi S.; Bale, Stuart D.

    2015-11-01

    Magnetohydronamic turbulence is believed to play a crucial role in heating laboratory, space, and astrophysical plasmas. However, the precise connection between the turbulent fluctuations and the particle kinetics has not yet been established. Here we present clear evidence of plasma turbulence heating based on diagnosed wave features and proton velocity distributions from solar wind measurements by the Wind spacecraft. For the first time, we can report the simultaneous observation of counter-propagating magnetohydrodynamic waves in the solar wind turbulence. As opposed to the traditional paradigm with counter-propagating Alfvén waves (AWs), anti-sunward AWs are encountered by sunward slow magnetosonic waves (SMWs) in this new type of solar wind compressible turbulence. The counter-propagating AWs and SWs correspond, respectively, to the dominant and sub-dominant populations of the imbalanced Elsässer variables. Nonlinear interactions between the AWs and SMWs are inferred from the non-orthogonality between the possible oscillation direction of one wave and the possible propagation direction of the other. The associated protons are revealed to exhibit bi-directional asymmetric beams in their velocity distributions: sunward beams appear in short, narrow patterns and anti-sunward in broad extended tails. It is suggested that multiple types of wave-particle interactions, i.e., cyclotron and Landau resonances with AWs and SMWs at kinetic scales, are taking place to jointly heat the protons perpendicular and in parallel.

  6. On the Causes of and Long Term Changes in Eurasian Heat Waves

    NASA Technical Reports Server (NTRS)

    Schubert, Siegfried; Wang, Hailan; Koster, Randal; Suarez, Max

    2012-01-01

    The MERRA reanalysis, other observations, and the GEOS-S model have been used to diagnose the causes of Eurasian heat waves including the recent extreme events that occurred in Europe during 2003 and in Russia during 2010. The results show that such extreme events are an amplification of natural patterns of atmospheric variability (in this case a particular large-scale atmospheric planetary wave) that develop over the Eurasian continent as a result of internal atmospheric forcing. The amplification occurs when the wave occasionally becomes locked in place for several weeks to months resulting in extreme heat and drying with the location depending on the phase of the upper atmospheric wave. Model experiments suggest that forcing from both the ocean (SST) and land playa role phase-locking the waves. An ensemble of very long GEOS-S model simulations (spanning the 20th century) forced with observed SST and greenhouse gases show that the model is capable of generating very similar heat waves, and that they have become more extreme in the last thirty years as a result of the overall warming of the Asian continent.

  7. Heating of the solar corona by the resonant absorption of Alfven waves

    NASA Technical Reports Server (NTRS)

    Davila, Joseph M.

    1987-01-01

    An improved method for calculating the resonance absorption heating rate is discussed and the results are compared with observations in the solar corona. To accomplish this, the wave equation for a dissipative, compressible plasma is derived from the linearized magnetohydrodynamic equations for a plasma with transverse Alfven speed gradients. For parameters representative of the solar corona, it is found that a two-scale description of the wave motion is appropriate. The large-scale motion, which can be approximated as nearly ideal, has a scale which is on the order of the width of the loop. The small-scale wave, however, has a transverse scale much smaller than the width of the loop, with a width of about 0.3-250 km, and is highly dissipative. These two wave motions are coupled in a narrow resonance region in the loop where the global wave frequency equals the local Alfven wave frequency. Formally, this coupling comes about from using the method of matched asymptotic expansions to match the inner and outer (small and large scale) solutions. The resultant heating rate can be calculated from either of these solutions. A formula derived using the outer (ideal) solution is presented, and shown to be consistent with observations of heating and line broadening in the solar corona.

  8. Heating and acceleration of solar wind ions by turbulent wave spectrum in inhomogeneous expanding plasma

    NASA Astrophysics Data System (ADS)

    Ofman, Leon; Ozak, Nataly; Viñas, Adolfo F.

    2016-03-01

    Near the Sun (< 10Rs) the acceleration, heating, and propagation of the solar wind are likely affected by the background inhomogeneities of the magnetized plasma. The heating and the acceleration of the solar wind ions by turbulent wave spectrum in inhomogeneous plasma is studied using a 2.5D hybrid model. The hybrid model describes the kinetics of the ions, while the electrons are modeled as massless neutralizing fluid in an expanding box approach. Turbulent magnetic fluctuations dominated by power-law frequency spectra, which are evident from in-situ as well as remote sensing measurements, are used in our models. The effects of background density inhomogeneity across the magnetic field on the resonant ion heating are studied. The effect of super-Alfvénic ion drift on the ion heating is investigated. It is found that the turbulent wave spectrum of initially parallel propagating waves cascades to oblique modes, and leads to enhanced resonant ion heating due to the inhomogeneity. The acceleration of the solar wind ions is achieved by the parametric instability of large amplitude waves in the spectrum, and is also affected by the inhomogeneity. The results of the study provide the ion temperature anisotropy and drift velocity temporal evolution due to relaxation of the instability. The non-Maxwellian velocity distribution functions (VDFs) of the ions are modeled in the inhomogeneous solar wind plasma in the acceleration region close to the Sun.

  9. Heat-flow equation motivated by the ideal-gas shock wave.

    PubMed

    Holian, Brad Lee; Mareschal, Michel

    2010-08-01

    We present an equation for the heat-flux vector that goes beyond Fourier's Law of heat conduction, in order to model shockwave propagation in gases. Our approach is motivated by the observation of a disequilibrium among the three components of temperature, namely, the difference between the temperature component in the direction of a planar shock wave, versus those in the transverse directions. This difference is most prominent near the shock front. We test our heat-flow equation for the case of strong shock waves in the ideal gas, which has been studied in the past and compared to Navier-Stokes solutions. The new heat-flow treatment improves the agreement with nonequilibrium molecular-dynamics simulations of hard spheres under strong shockwave conditions.

  10. Dust heating by Alfvén waves using non-Maxwellian distribution function

    SciTech Connect

    Zubia, K.; Shah, H. A.; Yoon, P. H.

    2015-08-15

    Quasilinear theory is employed in order to evaluate the resonant heating rate by Alfvén waves, of multiple species dust particles in a hot, collisionless, and magnetized plasma, with the underlying assumption that the dust velocity distribution function can be modeled by a generalized (r, q) distribution function. The kinetic linear dispersion relation for the electromagnetic dust cyclotron Alfvén waves is derived, and the dependence of the heating rate on the magnetic field, mass, and density of the dust species is subsequently investigated. The heating rate and its dependence on the spectral indices r and q of the distribution function are also investigated. It is found that the heating is sensitive to negative value of spectral index r.

  11. Heat-flow equation motivated by the ideal-gas shock wave.

    PubMed

    Holian, Brad Lee; Mareschal, Michel

    2010-08-01

    We present an equation for the heat-flux vector that goes beyond Fourier's Law of heat conduction, in order to model shockwave propagation in gases. Our approach is motivated by the observation of a disequilibrium among the three components of temperature, namely, the difference between the temperature component in the direction of a planar shock wave, versus those in the transverse directions. This difference is most prominent near the shock front. We test our heat-flow equation for the case of strong shock waves in the ideal gas, which has been studied in the past and compared to Navier-Stokes solutions. The new heat-flow treatment improves the agreement with nonequilibrium molecular-dynamics simulations of hard spheres under strong shockwave conditions. PMID:20866940

  12. [Local heating of murine skin by millimeter waves based on HBHE].

    PubMed

    Hu, Shuang-Xi; Fan, Chun-Li; Yang, Li; Sun, Feng-Rui

    2012-07-01

    The authors deduced Gaussian function of millimeter wave power distribution, and built up a transient thermal multilayer model for the heating of murine skin by high power millimeter waves with finite volume method (FVM) based on HBHE in the present paper. We analyzed the calculated results and compared them with the results calculated by Pennes' equation and the experimental ones; found that the temperature calculated by HBHE was more reasonable. Especially under high power millimeter wave, the calculated results were basically consistent with the experimental ones, and the superiority of the theoretical model was confirmed.

  13. Heating of coronal loops by phase-mixid shear Alfven waves

    NASA Technical Reports Server (NTRS)

    Abdelatif, Toufik E.

    1987-01-01

    The dissipation of shear Alfven waves in a coronal loop driven externally by an incident wave in the subcoronal region is investigated. The phase mixing of these incident shear Alfven waves serves as the dissipation mechanism in the corona. The wave solution found by Heyvaerts and Priest (1983) for coronal holes is used to compute the total energy deposited in a loop. The energy deposited is shown to depend upon the magnetic diffusivity nu(m) and viscosity nu(v), contrary to the conclusion of authors who assumed that coronal loops are perfect resonators. The energy deposited in a three-layer model is computed for incident waves with periods of five minutes or five seconds. For a five-minute period, almost no energy is deposited, especially for small loops. For a five-second period, a substantial amount of energy is deposited in the loop, but not enough to account for the heating of small loops.

  14. Measuring the effects of heat wave episodes on the human body's thermal balance.

    PubMed

    Katavoutas, George; Theoharatos, George; Flocas, Helena A; Asimakopoulos, Dimosthenis N

    2009-03-01

    During the peak of an extensive heat wave episode on 23-25 July 2007, simultaneous thermophysiological measurements were made in two non-acclimated healthy adults of different sex in a suburban area of Greater Athens, Greece. Based on experimental measurements of mean skin temperature and metabolic heat production, heat fluxes to and from the human body were calculated, and the biometeorological index heat load (HL) produced was determined according to the heat balance equation. Comparing experimental values with those derived from theoretical estimates revealed a great heat stress for both individuals, especially the male, while theoretical values underestimated heat stress. The study also revealed that thermophysiological factors, such as mean skin temperature and metabolic heat production, play an important role in determining heat fluxes patterns in the heat balance equation. The theoretical values of mean skin temperature as derived from an empirical equation may not be appropriate to describe the changes that take place in a non-acclimated individual. Furthermore, the changes in metabolic heat production were significant even for standard activity. PMID:19137329

  15. Measuring the effects of heat wave episodes on the human body's thermal balance.

    PubMed

    Katavoutas, George; Theoharatos, George; Flocas, Helena A; Asimakopoulos, Dimosthenis N

    2009-03-01

    During the peak of an extensive heat wave episode on 23-25 July 2007, simultaneous thermophysiological measurements were made in two non-acclimated healthy adults of different sex in a suburban area of Greater Athens, Greece. Based on experimental measurements of mean skin temperature and metabolic heat production, heat fluxes to and from the human body were calculated, and the biometeorological index heat load (HL) produced was determined according to the heat balance equation. Comparing experimental values with those derived from theoretical estimates revealed a great heat stress for both individuals, especially the male, while theoretical values underestimated heat stress. The study also revealed that thermophysiological factors, such as mean skin temperature and metabolic heat production, play an important role in determining heat fluxes patterns in the heat balance equation. The theoretical values of mean skin temperature as derived from an empirical equation may not be appropriate to describe the changes that take place in a non-acclimated individual. Furthermore, the changes in metabolic heat production were significant even for standard activity.

  16. Measuring the effects of heat wave episodes on the human body's thermal balance

    NASA Astrophysics Data System (ADS)

    Katavoutas, George; Theoharatos, George; Flocas, Helena A.; Asimakopoulos, Dimosthenis N.

    2009-03-01

    During the peak of an extensive heat wave episode on 23-25 July 2007, simultaneous thermophysiological measurements were made in two non-acclimated healthy adults of different sex in a suburban area of Greater Athens, Greece. Based on experimental measurements of mean skin temperature and metabolic heat production, heat fluxes to and from the human body were calculated, and the biometeorological index heat load (HL) produced was determined according to the heat balance equation. Comparing experimental values with those derived from theoretical estimates revealed a great heat stress for both individuals, especially the male, while theoretical values underestimated heat stress. The study also revealed that thermophysiological factors, such as mean skin temperature and metabolic heat production, play an important role in determining heat fluxes patterns in the heat balance equation. The theoretical values of mean skin temperature as derived from an empirical equation may not be appropriate to describe the changes that take place in a non-acclimated individual. Furthermore, the changes in metabolic heat production were significant even for standard activity.

  17. Analysis of mesoscale heating by piston supported waves in granular metalized explosive

    NASA Astrophysics Data System (ADS)

    Chakravarthy, Sunada; Gonthier, Keith A.; Panchadhara, Rohan

    2013-07-01

    Deformation-induced heating of explosive composites is influenced by the material microstructure (i.e. porosity and particle sizes, shapes and packing), and component-specific thermomechanical properties and mass fractions. In this study, an explicit, 2D, Lagrangian finite and discrete element technique is used to examine thermomechanical fields in mixtures of explosive (HMX, C4H8N8O8) and metal particles (Al) induced by piston-supported deformation waves (piston speed 50 ⩽ Up ⩽ 500 m s-1). The mesoscale description uses a plane strain, thermoelastic-viscoplastic and friction constitutive theory to describe the motion and deformation of individual particles, and an energy consistent, penalty based method to describe inter-particle contact. The deformation response of material having an initial solid volume fraction of φs0 = 0.835 (porosity 1 - φs0 = 0.165) is characterized for different metal mass fractions and wave strengths. Transition from a strength-dominated to a pressure-dominated wave structure is predicted to occur with increasing wave strength due to the elimination of porosity. Average thermomechanical fields that define the effective wave structure differ both qualitatively and quantitatively for the two types of structures. Explosive component mass locally heated to elevated temperature behind waves is shown to be affected by the wave structure and the value of friction coefficient.

  18. Wave propagation and noncollisional heating in neutral loop and helicon discharges

    SciTech Connect

    Celik, Y.; Crintea, D. L.; Luggenhoelscher, D.; Czarnetzki, U.; Ishijima, T.; Sugai, H.

    2011-02-15

    Heating mechanisms in two types of magnetized low pressure rf (13.56 MHz) discharges are investigated: a helicon discharge and a neutral loop discharge. Radial B-dot probe measurements demonstrate that the neutral loop discharge is sustained by helicon waves as well. Axial B-dot probe measurements reveal standing wave and beat patterns depending on the dc magnetic field strength and plasma density. In modes showing a strong wave damping, the plasma refractive index attains values around 100, leading to electron-wave interactions. In strongly damped modes, the radial plasma density profiles are mainly determined by power absorption of the propagating helicon wave, whereas in weakly damped modes, inductive coupling dominates. Furthermore, an azimuthal diamagnetic drift is identified. Measurements of the helicon wave phase demonstrate that initial plane wave fronts are bent during their axial propagation due to the inhomogeneous density profile. A developed analytical standing wave model including Landau damping reproduces very well the damping of the axial helicon wave field. This comparison underlines the theory whereupon Landau damping of electrons traveling along the field lines at speeds close to the helicon phase velocity is the main damping mechanism in both discharges.

  19. DNA--a molecule in search of additional functions: recipient of pool wave emissions? A hypothesis.

    PubMed

    Doerfler, Walter

    2010-09-01

    Almost the entire nucleotide sequence of human DNA is functionally unaccounted for, although large parts of the human genome are transcribed. The genes, as defined by current molecular biology, comprise about 1.5-2% of the DNA molecule. It is proposed that DNA encodes additional, hitherto unrecognized functions. In this discussion, the total information inside and outside the universe we live in is termed the pool or the sum total, known or unknown, of all laws, matter, energy, concepts and events. In a hypothetical model, a Gedankenexperiment, it is suggested that the total of all information emits pool waves of an unknown physical nature. They could be related to black energy or have completely different qualities. The designation pool waves should not imply any similarity to electromagnetism. Further, DNA is suggested to have the capability of interacting with the pool waves and thus permit humans - to some partly genetically determined and yet very limited extent - to perceive information from the pool. Pool emissions might be one of the forces that have been instrumental in and are still driving evolution from simple oligonucleotides to DNA with ever more complex recipient capacities. It will be a major challenge for researchers in the field to unravel these and less hypothetical undetected coding principles in DNA. It is uncertain whether the current trend to search the available DNA sequences with ever more refined computer technology on the basis of our present understanding of biology will detect unknown coding systems. For molecular medicine, research into the genetics of the most common human diseases could profit from the elucidation of presently still ephemeral codes in human DNA. Young scientists with a proven record of original research deserve support for the pursuit of unconventional ideas. This concept of granting priorities will be of the utmost importance in advancing the field beyond current concepts in molecular biology.

  20. Individual and public-program adaptation: coping with heat waves in five cities in Canada.

    PubMed

    Alberini, Anna; Gans, Will; Alhassan, Mustapha

    2011-12-01

    Heat Alert and Response Systems (HARS) are currently undergoing testing and implementation in Canada. These programs seek to reduce the adverse health effects of heat waves on human health by issuing weather forecasts and warnings, informing individuals about possible protections from excessive heat, and providing such protections to vulnerable subpopulations and individuals at risk. For these programs to be designed effectively, it is important to know how individuals perceive the heat, what their experience with heat-related illness is, how they protect themselves from excessive heat, and how they acquire information about such protections. In September 2010, we conducted a survey of households in 5 cities in Canada to study these issues. At the time of the survey, these cities had not implemented heat outreach and response systems. The study results indicate that individuals' recollections of recent heat wave events were generally accurate. About 21% of the sample reported feeling unwell during the most recent heat spell, but these illnesses were generally minor. Only in 25 cases out of 243, these illnesses were confirmed or diagnosed by a health care professional. The rate at which our respondents reported heat-related illnesses was higher among those with cardiovascular and respiratory illnesses, was higher among younger respondents and bore no relationship with the availability of air conditioning at home. Most of the respondents indicated that they would not dismiss themselves as "not at risk" and that they would cope with excessive heat by staying in air conditioned environments and keeping well hydrated. Despite the absence of heat outreach and education programs in their city, our respondents at least a rough idea of how to take care of themselves. The presence of air conditioning and knowledge of cooling centers is location-specific, which provides opportunities for targeting HARS interventions.

  1. Individual and Public-Program Adaptation: Coping with Heat Waves in Five Cities in Canada

    PubMed Central

    Alberini, Anna; Gans, Will; Alhassan, Mustapha

    2011-01-01

    Heat Alert and Response Systems (HARS) are currently undergoing testing and implementation in Canada. These programs seek to reduce the adverse health effects of heat waves on human health by issuing weather forecasts and warnings, informing individuals about possible protections from excessive heat, and providing such protections to vulnerable subpopulations and individuals at risk. For these programs to be designed effectively, it is important to know how individuals perceive the heat, what their experience with heat-related illness is, how they protect themselves from excessive heat, and how they acquire information about such protections. In September 2010, we conducted a survey of households in 5 cities in Canada to study these issues. At the time of the survey, these cities had not implemented heat outreach and response systems. The study results indicate that individuals’ recollections of recent heat wave events were generally accurate. About 21% of the sample reported feeling unwell during the most recent heat spell, but these illnesses were generally minor. Only in 25 cases out of 243, these illnesses were confirmed or diagnosed by a health care professional. The rate at which our respondents reported heat-related illnesses was higher among those with cardiovascular and respiratory illnesses, was higher among younger respondents and bore no relationship with the availability of air conditioning at home. Most of the respondents indicated that they would not dismiss themselves as “not at risk” and that they would cope with excessive heat by staying in air conditioned environments and keeping well hydrated. Despite the absence of heat outreach and education programs in their city, our respondents at least a rough idea of how to take care of themselves. The presence of air conditioning and knowledge of cooling centers is location-specific, which provides opportunities for targeting HARS interventions. PMID:22408596

  2. Drag reducing effects of polymer additives in a plate heat exchanger for the OTEC system

    SciTech Connect

    Kim, N.; Yoon, S.; Kim, C.; Seo, T.

    1999-07-01

    Experiments were undertaken for a 15kW Alfa-Laval plate heat exchanger utilizing polyethylene oxide as a polymer additive. Concentrations of polymer additives were 5, 10, 20, 30, 40, 50, 100, 200 and 400 wppm at 25 C and mass flow rates were 0.6kg/s, 0.7kg/s, 0.8kg/s and 0.9kg/s in normal operating ranges of the plate heat exchanger. The maximum effects of drag reductions were found at 20 wppm polymer concentration and at approximately 0.7kg/s of mass flow rate. The results show that there exist optimum polymer concentration and at approximately 0.7kg/s of mass flow rate. The results show that there exist optimum polymer concentration and mass flow rate for the plate heat exchanger for maximum drag reduction effects. In most cases, drag reduction of approximately 20% has been obtained. It means considerable savings in pumping power for a large size OTEC plant.

  3. Effect of the scrape-off layer in AORSA full wave simulations of fast wave minority, mid/high harmonic, and helicon heating regimes

    SciTech Connect

    Bertelli, N. Gerhardt, S.; Hosea, J. C.; LeBlanc, B.; Perkins, R. J.; Phillips, C. K.; Taylor, G.; Valeo, E. J.; Wilson, J. R.; Jaeger, E. F.; Lau, C.; Blazevski, D.; Green, D. L.; Berry, L.; Ryan, P. M.; Bonoli, P. T.; Wright, J. C.; Pinsker, R. I.; Prater, R.; Qin, C. M.; and others

    2015-12-10

    Several experiments on different machines and in different fast wave (FW) heating regimes, such as hydrogen minority heating and high harmonic fast waves, have found strong interactions between radio-frequency (RF) waves and the scrape-off layer (SOL) region. This paper examines the propagation and the power loss in the SOL by using the full wave code AORSA, in which the edge plasma beyond the last closed flux surface (LCFS) is included in the solution domain and a collisional damping parameter is used as a proxy to represent the real, and most likely nonlinear, damping processes. 3D AORSA results for the National Spherical Torus eXperiment (NSTX), where a full antenna spectrum is reconstructed, are shown, confirming the same behavior found for a single toroidal mode results in Bertelli et al, Nucl. Fusion, 54 083004, 2014, namely, a strong transition to higher SOL power losses (driven by the RF field) when the FW cut-off is moved away from in front of the antenna by increasing the edge density. Additionally, full wave simulations have been extended to “conventional” tokamaks with higher aspect ratios, such as the DIII-D, Alcator C-Mod, and EAST devices. DIII-D results show similar behavior found in NSTX and NSTX-U, consistent with previous DIII-D experimental observations. In contrast, a different behavior has been found for Alcator C-Mod and EAST, which operate in the minority heating regime unlike NSTX/NSTX-U and DIII-D, which operate in the mid/high harmonic regime. A substantial discussion of some of the main aspects, such as (i) the pitch angle of the magnetic field; (ii) minority heating vs. mid/high harmonic regimes is presented showing the different behavior of the RF field in the SOL region for NSTX-U scenarios with different plasma current. Finally, the preliminary results of the impact of the SOL region on the evaluation of the helicon current drive efficiency in DIII-D is presented for the first time and briefly compared with the different regimes

  4. Effect of the scrape-off layer in AORSA full wave simulations of fast wave minority, mid/high harmonic, and helicon heating regimes

    SciTech Connect

    Bertelli, Nicola; Jaeger, E. F.; Lau, Cornwall H; Blazevski, Dan; Green, David L; Berry, Lee Alan; Bonoli, P. T.; Gerhardt, S.P.; Hosea, J. C.; LeBlanc, B.; Perkins, R. J.; Phillips, Cynthia; Pinsker, R. I.; Prater, R.; Qin, C M; Ryan, P. M.; Taylor, G.; Valeo, E. J.; Wilson, Randy; Wright, J.; Zhang, X J

    2015-01-01

    Several experiments on different machines and in different fast wave (FW) heating regimes, such as hydrogen minority heating and high harmonic fast waves, have found strong interactions between radio-frequency (RF) waves and the scrape-off layer (SOL) region. This paper examines the propagation and the power loss in the SOL by using the full wave code AORSA, in which the edge plasma beyond the last closed flux surface (LCFS) is included in the solution domain and a collisional damping parameter is used as a proxy to represent the real, and most likely nonlinear, damping processes. 3D AORSA results for the National Spherical Torus eXperiment (NSTX), where a full antenna spectrum is reconstructed, are shown, confirming the same behavior found for a single toroidal mode results in Bertelli et al, Nucl. Fusion, 54 083004, 2014, namely, a strong transition to higher SOL power losses (driven by the RF field) when the FW cut-off is moved away from in front of the antenna by increasing the edge density. Additionally, full wave simulations have been extended to "conventional" tokamaks with higher aspect ratios, such as the DIII-D, Alcator C-Mod, and EAST devices. DIII-D results show similar behavior found in NSTX and NSTX-U, consistent with previous DIII-D experimental observations. In contrast, a different behavior has been found for Alcator C-Mod and EAST, which operate in the minority heating regime unlike NSTX/NSTX-U and DIII-D, which operate in the mid/high harmonic regime. A substantial discussion of some of the main aspects, such as (i) the pitch angle of the magnetic field; (ii) minority heating vs. mid/high harmonic regimes is presented showing the different behavior of the RF field in the SOL region for NSTX-U scenarios with different plasma current. Finally, the preliminary results of the impact of the SOL region on the evaluation of the helicon current drive efficiency in DIII-D is presented for the first time and briefly compared with the different regimes

  5. Recent changes in air temperature, heat waves occurrences, and atmospheric circulation in Northern Africa

    NASA Astrophysics Data System (ADS)

    Fontaine, Bernard; Janicot, Serge; Monerie, Paul-Arthur

    2013-08-01

    study documents the time evolution of air temperature and heat waves occurrences over Northern Africa for the period 1979-2011. A significant warming (1°-3°C), appearing by the mid-1960s over Sahara and Sahel, is associated with higher/lesser frequency of warm/cold temperatures, as with longer duration and higher occurrences of heat waves. Heat waves episodes of at least 4 day duration have been examined after removing the long-term evolution. These episodes are associated with specific anomalies: (i) in spring, positive low-level temperature anomalies over the Sahel and Sahara; low and midlevel cyclonic rotation over Morocco associated with a Rossby wave pattern, lessening the Harmattan; more/less atmospheric moisture westward/eastward to 0°; upward/downward anomalies above the western/eastern regions associated with the Rossby wave pattern; (ii) in summer, a similar but weaker positive low-level temperature anomaly (up to 3°C); less moisture westward to 10°W, a cyclonic anomaly in central Sahel favoring the monsoon eastward to 0° and a midlevel anticyclonic anomaly over the Western Sahara, increasing southward the flux divergence associated with the African Easterly Jet. In March-May, two to three heat waves propagate eastward. They are preceded by an abnormal warm cell over Libya and southwesterlies over the West Sahara. A large trough stands over North Atlantic while midtropospheric subsidence and anticyclonic rotation reinforce over the continent, then migrates toward the Arabian peninsula in breaking up. These signals are spatially coherent and might suggest the role of short Rossby waves with an eastward group velocity and a baroclinic mode, possibly associated with jet stream deformation.

  6. Projection of temperature and heat waves for Africa with an ensemble of CORDEX Regional Climate Models

    NASA Astrophysics Data System (ADS)

    Dosio, Alessandro

    2016-09-01

    The most severe effects of global warning will be related to the frequency and severity of extreme events. We provide an analysis of projections of temperature and related extreme events for Africa based on a large ensemble of Regional Climate Models from the COordinated Regional climate Downscaling EXperiment (CORDEX). Results are presented not only by means of widely used indices but also with a recently developed Heat Wave Magnitude Index-daily (HWMId), which takes into account both heat wave duration and intensity. Results show that under RCP8.5, warming of more than 3.5 °C is projected in JFM over most of the continent, whereas in JAS temperatures over large part of Northern Africa, the Sahara and the Arabian peninsula are projected to increase up to 6 °C. Large increase in in the number of warm days (Tx90p) is found over sub equatorial Africa, with values up to more than 90 % in JAS, and more than 80 % in JFM over e.g., the gulf of Guinea, Central African Republic, South Sudan and Ethiopia. Changes in Tn90p (warm nights) are usually larger, with some models projecting Tn90p reaching 95 % starting from around 2060 even under RCP4.5 over the Gulf of Guinea and the Sahel. Results also show that the total length of heat spells projected to occur normally (i.e. once every 2 years) under RCP8.5 may be longer than those occurring once every 30 years under the lower emission scenario. By employing the recently developed HWMId index, it is possible to investigate the relationship between heat wave length ad intensity; in particular it is shown that very intense heat waves such as that occurring over the Horn of Africa may have values of HWMId larger than that of longer, but relatively weak, heat waves over West Africa.

  7. Heat transfer and material flow during laser assisted multi-layer additive manufacturing

    SciTech Connect

    Manvatkar, V.; De, A.; DebRoy, T.

    2014-09-28

    A three-dimensional, transient, heat transfer, and fluid flow model is developed for the laser assisted multilayer additive manufacturing process with coaxially fed austenitic stainless steel powder. Heat transfer between the laser beam and the powder particles is considered both during their flight between the nozzle and the growth surface and after they deposit on the surface. The geometry of the build layer obtained from independent experiments is compared with that obtained from the model. The spatial variation of melt geometry, cooling rate, and peak temperatures is examined in various layers. The computed cooling rates and solidification parameters are used to estimate the cell spacings and hardness in various layers of the structure. Good agreement is achieved between the computed geometry, cell spacings, and hardness with the corresponding independent experimental results.

  8. Alfvén wave solar model (AWSoM): Coronal heating

    SciTech Connect

    Van der Holst, B.; Sokolov, I. V.; Meng, X.; Jin, M.; Manchester, W. B. IV; Tóth, G.; Gombosi, T. I.

    2014-02-20

    We present a new version of the Alfvén wave solar model, a global model from the upper chromosphere to the corona and the heliosphere. The coronal heating and solar wind acceleration are addressed with low-frequency Alfvén wave turbulence. The injection of Alfvén wave energy at the inner boundary is such that the Poynting flux is proportional to the magnetic field strength. The three-dimensional magnetic field topology is simulated using data from photospheric magnetic field measurements. This model does not impose open-closed magnetic field boundaries; those develop self-consistently. The physics include the following. (1) The model employs three different temperatures, namely the isotropic electron temperature and the parallel and perpendicular ion temperatures. The firehose, mirror, and ion-cyclotron instabilities due to the developing ion temperature anisotropy are accounted for. (2) The Alfvén waves are partially reflected by the Alfvén speed gradient and the vorticity along the field lines. The resulting counter-propagating waves are responsible for the nonlinear turbulent cascade. The balanced turbulence due to uncorrelated waves near the apex of the closed field lines and the resulting elevated temperatures are addressed. (3) To apportion the wave dissipation to the three temperatures, we employ the results of the theories of linear wave damping and nonlinear stochastic heating. (4) We have incorporated the collisional and collisionless electron heat conduction. We compare the simulated multi-wavelength extreme ultraviolet images of CR2107 with the observations from STEREO/EUVI and the Solar Dynamics Observatory/AIA instruments. We demonstrate that the reflection due to strong magnetic fields in the proximity of active regions sufficiently intensifies the dissipation and observable emission.

  9. Contribution of soil moisture in summer heat waves amplitude in MED-CORDEX simulations

    NASA Astrophysics Data System (ADS)

    Stéfanon, M.

    2012-04-01

    Contribution of soil moisture in summer heat wave amplitude in MED-CORDEX simulations Marc Stéfanon(1), Philippe Drobinski(1), Fabio D'Andrea(1), Cindy-Lebeaupin Brossier(1,2), (1) IPSL/LMD, France; (2) CNRM, France ; Heat waves and droughts are extreme weather events intrinsically linked, through strong coupling between the Earth's energy and water cycles. Their impact in short and medium term can be considerable on our societies in terms of health, socio-economic and ecological damage, as in 2003 in Western Europe or Russia in 2010. They are even more affected by climate change than the average state of the atmosphere and could be more frequent, more intense and more extended in the future. Besides this effect could be enhanced by the fact that Mediterranean, a vulnerable area of important geographic and climatic contrasts, is among the most responsive to global warming. If triggering of heat waves is determined by the large scale, land surface-related processes and feedbacks can amplify or inhibit heat trough several feedback mechanism. In regional climate models (RCMs) the land surface model (LSM) plays a key role in energy and water exchanges between land and atmosphere and determine the partitioning of surface fluxes (the relationship of latent heat flux to sensible heat flux). In the frame of the HyMeX and MED-CORDEX programs, two simulations at 20-km grid resolution have been performed over 1989-2008 with 2 different LSMs (RUC and 5-layer diffusive schemes) on a Mediterranean domain. The control simulation (CTL) corresponds to the RUC configuration, whereas experiment with perturbed soil moisture (WET) corresponds to the 5-layer diffusive scheme. CTL is able to correctly simulates temporal and spatial variations of soil moisture, as drought conditions. WET has a high soil moisture value, constant through time and land use dependant. These simulations are inter-compared to provide an estimate of the soil moisture contribution to heat wave amplitude.

  10. On the physics of waves in the solar atmosphere: Wave heating and wind acceleration

    NASA Technical Reports Server (NTRS)

    Musielak, Z. E.

    1994-01-01

    New calculations of the acoustic wave energy fluxes generated in the solar convective zone have been performed. The treatment of convective turbulence in the sun and solar-like stars, in particular, the precise nature of the turbulent power spectrum has been recognized as one of the most important issues in the wave generation problem. Several different functional forms for spatial and temporal spectra have been considered in the literature and differences between the energy fluxes obtained for different forms often exceed two orders of magnitude. The basic criterion for choosing the appropriate spectrum was the maximal efficiency of the wave generation. We have used a different approach based on physical and empirical arguments as well as on some results from numerical simulation of turbulent convection.

  11. Recent Additions in the Modeling Capabilities of an Open-Source Wave Energy Converter Design Tool: Preprint

    SciTech Connect

    Tom, N.; Lawson, M.; Yu, Y. H.

    2015-04-20

    WEC-Sim is a midfidelity numerical tool for modeling wave energy conversion devices. The code uses the MATLAB SimMechanics package to solve multibody dynamics and models wave interactions using hydrodynamic coefficients derived from frequency-domain boundary-element methods. This paper presents the new modeling features introduced in the latest release of WEC-Sim. The first feature discussed conversion of the fluid memory kernel to a state-space form. This enhancement offers a substantial computational benefit after the hydrodynamic body-to-body coefficients are introduced and the number of interactions increases exponentially with each additional body. Additional features include the ability to calculate the wave-excitation forces based on the instantaneous incident wave angle, allowing the device to weathervane, as well as import a user-defined wave elevation time series. A review of the hydrodynamic theory for each feature is provided and the successful implementation is verified using test cases.

  12. Force on a heated sphere in a horizontal plane acoustic standing wave field

    NASA Technical Reports Server (NTRS)

    Leung, E. W.; Wang, T. G.

    1985-01-01

    The force on a heated sphere in a horizontal plane acoustic standing wave field is the subject of this investigation. The heated sphere produces a thermal gradient in the resonance chamber. The force on the sphere in a direction perpendicular to that of gravity is measured. This force is enhanced in the region near the pressure node, and is weakened in the region near the pressure antinode. Measurements of the force on a heated sphere with sound pressure levels between 148 and 156 dB are presented.

  13. The 2010 Pakistan Flood and Russian Heat Wave: Teleconnection of Hydrometeorological Extremes

    NASA Technical Reports Server (NTRS)

    Lau, William K. M.; Kim, Kyu-Myong

    2012-01-01

    In this paper, preliminary results are presented showing that the two record-setting extreme events during 2010 summer (i.e., the Russian heat wave-wildfires and Pakistan flood) were physically connected. It is found that the Russian heat wave was associated with the development of an extraordinarily strong and prolonged extratropical atmospheric blocking event in association with the excitation of a large-scale atmospheric Rossby wave train spanning western Russia, Kazakhstan, and the northwestern China-Tibetan Plateau region. The southward penetration of upper-level vorticity perturbations in the leading trough of the Rossby wave was instrumental in triggering anomalously heavy rain events over northern Pakistan and vicinity in mid- to late July. Also shown are evidences that the Russian heat wave was amplified by a positive feedback through changes in surface energy fluxes between the atmospheric blocking pattern and an underlying extensive land region with below-normal soil moisture. The Pakistan heavy rain events were amplified and sustained by strong anomalous southeasterly flow along the Himalayan foothills and abundant moisture transport from the Bay of Bengal in connection with the northward propagation of the monsoonal intraseasonal oscillation.

  14. PROTON HEATING IN SOLAR WIND COMPRESSIBLE TURBULENCE WITH COLLISIONS BETWEEN COUNTER-PROPAGATING WAVES

    SciTech Connect

    He, Jiansen; Tu, Chuanyi; Wang, Linghua; Pei, Zhongtian; Marsch, Eckart; Chen, Christopher H. K.; Zhang, Lei; Salem, Chadi S.; Bale, Stuart D.

    2015-11-10

    Magnetohydronamic turbulence is believed to play a crucial role in heating laboratory, space, and astrophysical plasmas. However, the precise connection between the turbulent fluctuations and the particle kinetics has not yet been established. Here we present clear evidence of plasma turbulence heating based on diagnosed wave features and proton velocity distributions from solar wind measurements by the Wind spacecraft. For the first time, we can report the simultaneous observation of counter-propagating magnetohydrodynamic waves in the solar wind turbulence. As opposed to the traditional paradigm with counter-propagating Alfvén waves (AWs), anti-sunward AWs are encountered by sunward slow magnetosonic waves (SMWs) in this new type of solar wind compressible turbulence. The counter-propagating AWs and SWs correspond, respectively, to the dominant and sub-dominant populations of the imbalanced Elsässer variables. Nonlinear interactions between the AWs and SMWs are inferred from the non-orthogonality between the possible oscillation direction of one wave and the possible propagation direction of the other. The associated protons are revealed to exhibit bi-directional asymmetric beams in their velocity distributions: sunward beams appear in short, narrow patterns and anti-sunward in broad extended tails. It is suggested that multiple types of wave–particle interactions, i.e., cyclotron and Landau resonances with AWs and SMWs at kinetic scales, are taking place to jointly heat the protons perpendicular and in parallel.

  15. Projected intensification of subseasonal temperature variability and heat waves in the Great Plains

    NASA Astrophysics Data System (ADS)

    Teng, Haiyan; Branstator, Grant; Meehl, Gerald A.; Washington, Warren M.

    2016-03-01

    Compared to changes in the climatological mean temperature, we have less confidence in how much and by what mechanisms temperature variability may be affected by anthropogenic climate change. Here based on a 30-member climate change projection from an earth system model, we find that summertime subseasonal temperature variability in the U.S. Great Plains is enhanced by approximately 20% in 2070-2100 relative to 1980-2010. In particular, daily temperature departures from the new climatologies during future heat waves are on average 0.6°C warmer than are the corresponding departures under present-day conditions. Although in both periods heat waves in the Great Plains tend to be associated with planetary wave events, the amplification of future heat waves does not appear to be induced by changes in planetary wave variability in the midlatitudes. Instead, in this experiment the strengthening appears to be primarily caused by enhanced local land-atmosphere feedbacks resulting from a warmer/drier future climate.

  16. Resilience to seasonal heat wave episodes in a Mediterranean pine forest.

    PubMed

    Tatarinov, Fedor; Rotenberg, Eyal; Maseyk, Kadmiel; Ogée, Jérôme; Klein, Tamir; Yakir, Dan

    2016-04-01

    Short-term, intense heat waves (hamsins) are common in the eastern Mediterranean region and provide an opportunity to study the resilience of forests to such events that are predicted to increase in frequency and intensity. The response of a 50-yr-old Aleppo pine (Pinus halepensis) forest to hamsin events lasting 1-7 d was studied using 10 yr of eddy covariance and sap flow measurements. The highest frequency of heat waves was c. four per month, coinciding with the peak productivity period (March-April). During these events, net ecosystem carbon exchange (NEE) and canopy conductance (gc ) decreased by c. 60%, but evapotranspiration (ET) showed little change. Fast recovery was also observed with fluxes reaching pre-stress values within a day following the event. NEE and gc showed a strong response to vapor pressure deficit that weakened as soil moisture decreased, while sap flow was primarily responding to changes in soil moisture. On an annual scale, heat waves reduced NEE and gross primary productivity by c. 15% and 4%, respectively. Forest resilience to short-term extreme events such as heat waves is probably a key to its survival and must be accounted for to better predict the increasing impact on productivity and survival of such events in future climates. PMID:27000955

  17. Analysis of heat wave occurrences in the Carpathian basin using regional climate model simulations

    NASA Astrophysics Data System (ADS)

    Bartha, E. B.; Pongracz, R.; Bartholy, J.

    2012-04-01

    Human health is very likely affected by regional consequences of global warming. One of the most severe impacts is probably associated to temperature-related climatological extremes, such as heat waves. In the coming decades hot conditions in most regions of the world are very likely to occur more frequently and more intensely than in the recent decades. In order to develop adaptation and mitigation strategies on local scale, it is essential to analyze the projected changes related to warming climatic conditions including heat waves. In 2004, a Heat Health Watch Warning System was developed in Hungary on the basis of a retrospective analysis of mortality and meteorological data to anticipate heat waves that may result in a large excess of mortality. In the frame of this recently introduced Health Watch System, three levels of heat wave warning are applied. They are associated to the daily mean temperature values, and defined as follows: - Warning level 1 (advisory for internal use) is issued when the daily mean temperature exceeds 25 °C. - Warning level 2 (heat wave watch) is issued when the daily mean temperature for at least 3 consecutive days exceeds 25 °C. - Warning level 3 (heat wave alert) is issued when the daily mean temperature for at least 3 consecutive days exceeds 27 °C. In the present study, frequency of the above climatic conditions are analyzed using regional climate model (RCM) experiments are analyzed for the recent past and the coming decades (1961-2100) for the Carpathian basin. At the Dept. of Meteorology, Eotvos Lorand University two different RCMs have been adapted: RegCM (with 10 km horizontal resolution, originally developed by Giorgi et al., currently, available from the International Centre for Theoretical Physics, ICTP) and PRECIS (with 25 km horizontal resolution, developed at the UK Met Office, Hadley Centre). Their initial and lateral boundary conditions have been provided by global climate models ECHAM and HadCM3, respectively. For

  18. Neonates in Ahmedabad, India, during the 2010 heat wave: a climate change adaptation study.

    PubMed

    Kakkad, Khyati; Barzaga, Michelle L; Wallenstein, Sylvan; Azhar, Gulrez Shah; Sheffield, Perry E

    2014-01-01

    Health effects from climate change are an international concern with urban areas at particular risk due to urban heat island effects. The burden of disease on vulnerable populations in non-climate-controlled settings has not been well studied. This study compared neonatal morbidity in a non-air-conditioned hospital during the 2010 heat wave in Ahmedabad to morbidity in the prior and subsequent years. The outcome of interest was neonatal intensive care unit (NICU) admissions for heat. During the months of April, May, and June of 2010, 24 NICU admissions were for heat versus 8 and 4 in 2009 and 2011, respectively. Both the effect of moving the maternity ward and the effect of high temperatures were statistically significant, controlling for each other. Above 42 degrees Celsius, each daily maximum temperature increase of a degree was associated with 43% increase in heat-related admissions (95% CI 9.2-88%). Lower floor location of the maternity ward within hospital which occurred after the 2010 heat wave showed a protective effect. These findings demonstrate the importance of simple surveillance measures in motivating a hospital policy change for climate change adaptation-here relocating one ward-and the potential increasing health burden of heat in non-climate-controlled institutions on vulnerable populations.

  19. Formation of a conical distribution and intense ion heating in the presence of hydrogen cyclotron waves

    NASA Astrophysics Data System (ADS)

    Okuda, H.; Ashour-Abdalla, M.

    1981-07-01

    In the considered investigation, it is assumed that the field aligned currents are responsible for producing electrostatic harmonic cyclotron waves (EHC). Using a one-dimensional simulation model in which the electron velocity distribution is maintained by a constant injection of the initial distribution, it is shown that, in contrast to earlier initial value simulations, EHC waves grow to a large amplitude, resulting in the formation of an anisotropic ion velocity distribution. Both the heating rate and the anisotropy are in reasonable agreement with the quasi-linear theory, taking into account the cyclotron resonance. The results show that the saturation is due to the combined effects of wave induced diffusion in an electron velocity space and the heating of ions perpendicularly. Both these effects reduce the growth rate.

  20. Supersonic Heat Wave Propagation in Laser-Produced Underdense Plasma for Efficient X-Ray Generation

    SciTech Connect

    Tanabe, M; Nishimura, H; Fujioka, S; Nagai, K; Iwamae, A; Ohnishi, N; Fournier, K B; Girard, F; Primout, M; Villette, B; Tobin, M; Mima, K

    2008-06-12

    We have observed supersonic heat wave propagation in a low-density aerogel target ({rho} {approx} 3.2 mg/cc) irradiated at the intensity of 4 x 10{sup 14} W/cm{sup 2}. The heat wave propagation was measured with a time-resolved x-ray imaging diagnostics, and the results were compared with simulations made with the two-dimensional radiation-hydrodynamic code, RAICHO. Propagation velocity of the ionization front gradually decreased as the wave propagates into the target. The reason of decrease is due to increase of laser absorption region as the front propagates and interplay of hydrodynamic motion and reflection of laser propagation. These features are well reported with the simulation.

  1. ELF/VLF wave generation from the beating of two HF ionospheric heating sources

    NASA Astrophysics Data System (ADS)

    Cohen, M. B.; Moore, R. C.; Golkowski, M.; Lehtinen, N. G.

    2012-12-01

    It is well established that Extremely Low Frequency (ELF, 0.3-3 kHz) and Very Low Frequency (VLF, 3-30 kHz) radio waves can be generated via modulated High Frequency (HF, 3-10 MHz) heating of the lower ionosphere (60-100 km). The ionospheric absorption of HF power modifies the conductivity of the lower ionosphere, which in the presence of natural currents such as the auroral electrojet, creates an `antenna in the sky.' We utilize a theoretical model of the HF to ELF/VLF conversion and the ELF/VLF propagation, and calculate the amplitudes of the generated ELF/VLF waves when two HF heating waves, separated by the ELF/VLF frequency, are transmitted from two adjacent locations. The resulting ELF/VLF radiation pattern exhibits a strong directional dependence (as much as 15 dB) that depends on the physical spacing of the two HF sources. This beat wave source can produce signals 10-20 dB stronger than those generated using amplitude modulation, particularly for frequencies greater than 5-10 kHz. We evaluate recent suggestions that beating two HF waves generates ELF/VLF waves in the F-region (>150 km), and conclude that those experimental results may have misinterpreted, and can be explained strictly by the much more well established D region mechanism.

  2. Alfven wave trapping, network microflaring, and heating in solar coronal holes

    NASA Technical Reports Server (NTRS)

    Moore, R. L.; Suess, S. T.; Musielak, Z. E.; An, C.-H.

    1991-01-01

    Fresh evidence that much of the heating in coronal holes is provided by Alfven waves is presented. This evidence comes from examining the reflection of Alfven waves in an isothermal hydrostatic model coronal hole with an open magnetic field. Reflection occurs if the wavelength is as long as the order of the scale height of the Alfven velocity. For Alfven waves with periods of about 5 min, and for realistic density, magnetic field strength, and magnetic field spreading in the model, the waves are reflected back down within the model hole if the coronal temperature is only slightly less than 1.0 x 10 to the 6th K, but are not reflected and escape out the top of the model if the coronal temperature is only slightly greater than 1.0 x 10 to the 6th K. Because the spectrum of Alfven waves in real coronal holes is expected to peak around 5 min and the temperature is observed to be close to 1.0 x 10 to the 6th K, the sensitive temperature dependence of the trapping suggests that the temperature in coronal holes is regulated by heating by the trapped Alfven waves.

  3. Lower solar chromosphere-corona transition region. II - Wave pressure effects for a specific form of the heating function

    NASA Technical Reports Server (NTRS)

    Woods, D. Tod; Holzer, Thomas E.; Macgregor, Keith B.

    1990-01-01

    Lower transition region models with a balance between mechanical heating and radiative losses are expanded to include wave pressure effects. The models are used to study the simple damping length form of the heating function. The results are compared to the results obtained by Woods et al. (1990) for solutions in the lower transition region. The results suggest that a mixture of fast-mode and slow-mode waves may provide the appropriate heating mechanism in the lower transition region, with the decline in effective vertical wave speed caused by the refraction and eventual total reflection of the fast-mode wave resulting from the decreasing atmospheric density.

  4. E × B shear pattern formation by radial propagation of heat flux waves

    SciTech Connect

    Kosuga, Y.; Diamond, P. H.; Dif-Pradalier, G.; Gürcan, Ö. D.

    2014-05-15

    A novel theory to describe the formation of E×B flow patterns by radially propagating heat flux waves is presented. A model for heat avalanche dynamics is extended to include a finite delay time between the instantaneous heat flux and the mean flux, based on an analogy between heat avalanche dynamics and traffic flow dynamics. The response time introduced here is an analogue of the drivers' response time in traffic dynamics. The microscopic foundation for the time delay is the time for mixing of the phase space density. The inclusion of the finite response time changes the model equation for avalanche dynamics from Burgers equation to a nonlinear telegraph equation. Based on the telegraph equation, the formation of heat flux jams is predicted. The growth rate and typical interval of jams are calculated. The connection of the jam interval to the typical step size of the E×B staircase is discussed.

  5. Test of a new heat-flow equation for dense-fluid shock waves.

    PubMed

    Holian, Brad Lee; Mareschal, Michel; Ravelo, Ramon

    2010-09-21

    Using a recently proposed equation for the heat-flux vector that goes beyond Fourier's Law of heat conduction, we model shockwave propagation in the dense Lennard-Jones fluid. Disequilibrium among the three components of temperature, namely, the difference between the kinetic temperature in the direction of a planar shock wave and those in the transverse directions, particularly in the region near the shock front, gives rise to a new transport (equilibration) mechanism not seen in usual one-dimensional heat-flow situations. The modification of the heat-flow equation was tested earlier for the case of strong shock waves in the ideal gas, which had been studied in the past and compared to Navier-Stokes-Fourier solutions. Now, the Lennard-Jones fluid, whose equation of state and transport properties have been determined from independent calculations, allows us to study the case where potential, as well as kinetic contributions are important. The new heat-flow treatment improves the agreement with nonequilibrium molecular-dynamics simulations under strong shock wave conditions, compared to Navier-Stokes.

  6. Test of a new heat-flow equation for dense-fluid shock waves.

    PubMed

    Holian, Brad Lee; Mareschal, Michel; Ravelo, Ramon

    2010-09-21

    Using a recently proposed equation for the heat-flux vector that goes beyond Fourier's Law of heat conduction, we model shockwave propagation in the dense Lennard-Jones fluid. Disequilibrium among the three components of temperature, namely, the difference between the kinetic temperature in the direction of a planar shock wave and those in the transverse directions, particularly in the region near the shock front, gives rise to a new transport (equilibration) mechanism not seen in usual one-dimensional heat-flow situations. The modification of the heat-flow equation was tested earlier for the case of strong shock waves in the ideal gas, which had been studied in the past and compared to Navier-Stokes-Fourier solutions. Now, the Lennard-Jones fluid, whose equation of state and transport properties have been determined from independent calculations, allows us to study the case where potential, as well as kinetic contributions are important. The new heat-flow treatment improves the agreement with nonequilibrium molecular-dynamics simulations under strong shock wave conditions, compared to Navier-Stokes. PMID:20866140

  7. Evaluation of heat-cured resin bases following the addition of denture teeth using a second heat cure.

    PubMed

    Polukoshko, K M; Brudvik, J S; Nicholls, J I; Smith, D E

    1992-04-01

    This study compared heat-cured acrylic resin denture baseplate distortions following a second heat cure used to add the denture teeth. The second heat cure was done with three different water-bath curing temperatures. The distortions were evaluated in three planes by use of a measuring microscope. Recorded distortions were not clinically significant.

  8. The possible role of high-frequency waves in heating solar coronal loops

    NASA Technical Reports Server (NTRS)

    Porter, Lisa J.; Klimchuk, James A.; Sturrock, Peter A.

    1994-01-01

    We investigate the role of high-frequency waves in the heating of solar active region coronal loops. We assume a uniform background magnetic field, and we introduce a density stratification in a direction perpendicular to this field. We focus on ion compressive viscosity as the damping mechanism of the waves. We incorporate viscosity self-consistently into the equations, and we derive a dispersion relation by adopting a slab model, where the density inside the slab is greater than that outside. Such a configuration supports two types of modes: surface waves and trapped body waves. In order to determine under what conditions these waves may contribute to the heating of active regions, we solve our dispersion relation for a range of densities, temperatures, magnetic field strengths, density ratios, wavevector magnitudes, wavevector ratios, and slab widths. We find that surface waves exhibit very small damping, but body waves can potentially damp at rates needed to balance radiative losses. However, the required frequencies of these body waves are very high. For example, the wave frequency must be at least 5.0/s for a slab density of 10(exp 9,5)/cc, a slab temperature of 10(exp 6,5) K, a field strength of 100 G, and a density ratio of 5. For a slab density of 10(exp 10)/cc, this frequency increases to 8.8/s. Although these frequencies are very high, there in no observational evidence to rule out their existence, and they may be generated both below the corona and at magnetic reconnection sites in the corona. However, we do find that, for slab densities of 10(exp 10)/cc or less, the dissipation of high-frequency waves will be insufficient to balance the radiative losses if the magnetic field strength exceeds roughly 200 G. Because the magnetic field is known to exceed 200 G in many active region loops, particularly low-lying loops and loops emanating from sunspots, it is unlikely that high-frequency waves can provide sufficient heating in these regions.

  9. Large scale atmospheric drivers for heat waves in the Mediterranean Basin

    NASA Astrophysics Data System (ADS)

    Pasqui, Massimiliano; Di Giuseppe, Edmondo

    2016-04-01

    West African Heat Low (WAHL) is one of the prominent dynamical components of the West African Monsoon (WAM) system playing a key role in the summer atmospheric circulation over Mediterranean as well. It is characterized by a semi-permanent low pressure system generated and maintained by surface heating over the western part of Saharan desert in summer, and a divergent flux pattern above the atmospheric boundary level. In this study we analyse the formation and occurrence of heat waves in the Mediterranean Basin connected to the WAHL regimes in combination with the subtropical anticyclone regimes over North Atlantic basin (the "Azore High") . In this work, heat waves are defined when more than 6 consecutive days with a daily temperature above 90th percentile corresponding threshold are observed. We use 1971-2000 as reference period for thresholds calculation, based on two datasets: a) the European Climate Assessment & Dataset (ECAD/E-OBS) data; b) the Berkeley-Earth Project data; the analysis period covers March-September from 1951 to 2015 and 1951 to 2011 respectively. The WAHL index is calculated following the method proposed by Chauvin et al. (2010) and based on NCAR/NCEP Reanalysis dataset, while the Azore High pressure system regimes variability are computed as in Davis et al. (1997). We show that a statistical relationship between heat waves in Western and Central Mediterranean Basin and WAHL mechanism exists, being the latter a prominent causal factor. The relationships and causal connections between WAHL and Azores High atmospheric systems are also analysed to highlight potential implications for heat waves outlooks and early warning systems.

  10. Pressure waves in liquid mercury target from pulsed heat loads and the possible way controlling their effects

    SciTech Connect

    Ni, L.; Skala, K.

    1996-06-01

    In ESS project liquid metals are selected as the main target for the pulsed spallation neutron source. Since the very high instantaneous energy is deposited on the heavy molten target in a very short period time, pressure waves are generated. They travel through the liquid and cause high stress in the container. Also, additional stress should be considered in the wall which is the result of direct heating of the target window. These dynamic processes were simulated with computational codes with the static response being analized first. The total resulting dynamic wall stress has been found to have exceeded the design stress for the selected container material. Adding a small amount of gas bubbles in the liquid could be a possible way to reduce the pressure waves.

  11. Generation of large scale field-aligned density irregularities in ionospheric heating experiments. [electromagnetic wave decay

    NASA Technical Reports Server (NTRS)

    Fejer, J. A.

    1974-01-01

    Threshold and growth rate for stimulated Brillouin scattering are calculated for a uniform magnetoplasma. These are then compared with the threshold and growth rate of a new thermal instability in which the nonlinear Lorentz force felt by the electrons at the beat frequency of the two electromagnetic waves is replaced by a pressure force due to differential heating in the interference pattern of the pump wave and the generated electromagnetic wave. This thermal instability, which is still essentially stimulated Brillouin scattering, has a threshold which is especially low when the propagation vector of the beat wave is almost normal to the magnetic field. The threshold is then considerably lower than the threshold for normal stimulated Brillouin scattering and therefore this new instability is probably responsible for the generation of large scale field aligned irregularities and ionospheric spread F.

  12. Theory of hysteresis during electron heating of electromagnetic wave scattering by self-organized dust structures in complex plasmas

    SciTech Connect

    Tsytovich, Vadim; Gusein-zade, Namik; Ignatov, Alexander

    2015-07-15

    Dust structuring is a natural and universal process in complex plasmas. The scattering of electromagnetic waves by dust structures is governed by the factor of coherency, i.e., the total number of coherent electrons in a single structure. In the present paper, we consider how the factor of coherency changes due to additional pulse electron heating and show that it obeys a hysteresis. After the end of the pulse heating, the scattering intensity differs substantially from that before heating. There are three necessary conditions for scattering hysteresis: first, the radiation wavelength should be larger than the pattern (structure) size; second, the total number of coherent electrons confined by the structure should be large; and third, the heating pulse duration should be shorter than the characteristic time of dust structure formation. We present the results of numerical calculations using existing models of self-consistent dust structures with either positively or negatively charged dust grains. It is shown that, depending on the grain charge and the ionization rate, two types of hysteresis are possible: one with a final increase of the scattering and the other with a final decrease of the scattering. It is suggested that the hysteresis of coherent scattering can be used as a tool in laboratory experiments and that it can be a basic mechanism explaining the observed hysteresis in radar scattering by noctilucent clouds during active experiments on electron heating in mesosphere.

  13. Thermal transport in shock wave-compressed solids using pulsed laser heating.

    PubMed

    La Lone, B M; Capelle, G; Stevens, G D; Turley, W D; Veeser, L R

    2014-07-01

    A pulsed laser heating method was developed for determining thermal transport properties of solids under shock-wave compression. While the solid is compressed, a laser deposits a known amount of heat onto the sample surface, which is held in the shocked state by a transparent window. The heat from the laser briefly elevates the surface temperature and then diffuses into the interior via one-dimensional heat conduction. The thermal effusivity is determined from the time history of the resulting surface temperature pulse, which is recorded with optical pyrometry. Thermal effusivity is the square root of the product of thermal conductivity and volumetric heat capacity and is the key thermal transport parameter for relating the surface temperature to the interior temperature of the sample in a dynamic compression experiment. Therefore, this method provides information that is needed to determine the thermodynamic state of the interior of a compressed metal sample from a temperature measurement at the surface. The laser heat method was successfully demonstrated on tin that was shock compressed with explosives to a stress and temperature of ~25 GPa and ~1300 K. In this state, tin was observed to have a thermal effusivity of close to twice its ambient value. The implications on determining the interior shock wave temperature of tin are discussed.

  14. Investigation of acoustic gravity waves created by anomalous heat sources: experiments and theoretical analysis

    NASA Astrophysics Data System (ADS)

    Pradipta, R.; Lee, M. C.

    2013-07-01

    We have been investigating high-power radio wave-induced acoustic gravity waves (AGWs) at Gakona, Alaska, using the High-frequency Active Aurora Research Program (HAARP) heating facility (i.e. HF heater) and extensive diagnostic instruments. This work was aimed at performing a controlled study of the space plasma turbulence triggered by the AGWs originating from anomalous heat sources, as observed in our earlier experiments at Arecibo, Puerto Rico (Pradipta 2007 MS Thesis MIT Press, Cambridge, MA). The HF heater operated in continuous wave (CW) O-mode can heat ionospheric plasmas effectively to yield a depleted magnetic flux tube as rising plasma bubbles (Lee et al 1998 Geophys. Res. Lett. 25 579). Two processes are responsible for the depletion of the magnetic flux tube: (i) thermal expansion and (ii) chemical reactions caused by heated ions. The depleted plasmas create large density gradients that can augment spread F processes via generalized Rayleigh-Taylor instabilities (Lee et al 1999 Geophys. Res. Lett. 26 37). It is thus expected that the temperature of neutral particles in the heated ionospheric region can be increased. Such a heat source in the neutral atmosphere may potentially generate AGWs in the form of traveling ionospheric plasma disturbances (TIPDs). We should point out that these TIPDs have features distinctively different from electric and magnetic field (ExB) drifts of HF wave-induced large-scale non-propagating plasma structures. Moreover, it was noted in our recent study of naturally occurring AGW-induced TIDs that only large-scale AGWs can propagate upward to reach higher altitudes. Thus, in our Gakona experiments we select optimum heating schemes for HF wave-induced AGWs that can be distinguished from the naturally occurring ones. The generation and propagation of AGWs are monitored by MUIR (Modular Ultra high-frequency Ionospheric Radar), Digisonde and GPS/low-earth-orbit satellites. Our theoretical and experimental studies have shown that

  15. Roles of convective heating and boundary-layer moisture asymmetry in slowing down the convectively coupled Kelvin waves

    NASA Astrophysics Data System (ADS)

    Wang, Lu; Li, Tim

    2016-06-01

    Mechanisms for an in-phase relationship between convection and low-level zonal wind and the slow propagation of the convectively coupled Kelvin wave (CCKW) are investigated by analyzing satellite-based brightness temperature and reanalysis data and by constructing a simple theoretical model. Observational data analysis reveals an eastward shift of the low-level convergence and moisture relative to the CCKW convective center. The composite vertical structures show that the low-level convergence lies in the planetary boundary layer (PBL) (below 800 hPa), and is induced by the pressure trough above the top of PBL through an Ekman-pumping process. A traditional view of a slower eastward propagation speed compared to the dry Kelvin waves is attributed to the reduction of atmospheric static stability in mid-troposphere due to the convective heating effect. The authors' quantitative assessment of the heating effect shows that this effect alone cannot explain the observed CCKW phase speed. We hypothesize that additional slowing process arises from the effect of zonally asymmetric PBL moisture. A simple theoretical model is constructed to understand the relative role of the heating induced effective static stability effect and the PBL moisture effect. The result demonstrates the important role of the both effects. Thus, PBL-free atmosphere interaction is important in explaining the observed structure and propagation of CCKW.

  16. Preferential heating of oxygen 5+ ions by finite-amplitude oblique Alfvén waves

    NASA Astrophysics Data System (ADS)

    Maneva, Yana G.; Viñas, Adolfo; Araneda, Jaime; Poedts, Stefaan

    2016-03-01

    Minor ions in the fast solar wind are known to have higher temperatures and to flow faster than protons in the interplanetary space. In this study we combine previous research on parametric instability theory and 2.5D hybrid simulations to study the onset of preferential heating of Oxygen 5+ ions by large-scale finite-amplitude Alfvén waves in the collisionless fast solar wind. We consider initially non-drifting isotropic multi-species plasma, consisting of isothermal massless fluid electrons, kinetic protons and kinetic Oxygen 5+ ions. The external energy source for the plasma heating and energization are oblique monochromatic Alfvén-cyclotron waves. The waves have been created by rotating the direction of initial parallel pump, which is a solution of the multi-fluid plasma dispersion relation. We consider propagation angles θ ≤ 30°. The obliquely propagating Alfvén pump waves lead to strong diffusion in the ion phase space, resulting in highly anisotropic heavy ion velocity distribution functions and proton beams. We discuss the application of the model to the problems of preferential heating of minor ions in the solar corona and the fast solar wind.

  17. Heat and immunity: an experimental heat wave alters immune functions in three-spined sticklebacks (Gasterosteus aculeatus).

    PubMed

    Dittmar, Janine; Janssen, Hannah; Kuske, Andra; Kurtz, Joachim; Scharsack, Jörn P

    2014-07-01

    Global climate change is predicted to lead to increased temperatures and more extreme climatic events. This may influence host-parasite interactions, immunity and therefore the impact of infectious diseases on ecosystems. However, little is known about the effects of rising temperatures on immune defence, in particular in ectothermic animals, where the immune system is directly exposed to external temperature change. Fish are ideal models for studying the effect of temperature on immunity, because they are poikilothermic, but possess a complete vertebrate immune system with both innate and adaptive immunity. We used three-spined sticklebacks ( Gasterosteus aculeatus) originating from a stream and a pond, whereby the latter supposedly were adapted to higher temperature variation. We studied the effect of increasing and decreasing temperatures and a simulated heat wave with subsequent recovery on body condition and immune parameters. We hypothesized that the immune system might be less active at low temperatures, but will be even more suppressed at temperatures towards the upper tolerable temperature range. Contrary to our expectation, we found innate and adaptive immune activity to be highest at a temperature as low as 13 °C. Exposure to a simulated heat wave induced long-lasting immune disorders, in particular in a stickleback population that might be less adapted to temperature variation in its natural environment. The results show that the activity of the immune system of an ectothermic animal species is temperature dependent and suggest that heat waves associated with global warming may immunocompromise host species, thereby potentially facilitating the spread of infectious diseases.

  18. Generation of Large-scale Thermospheric Disturbances and Thermosphere Heating by Infrasonic Waves Propagated from Tropospheric Sources

    NASA Astrophysics Data System (ADS)

    Kshevetskii, Sergey; Gavrilov, Nikolay; Karpov, Ivan; Kurdyaeva, Yuliya

    2015-04-01

    Meteorological processes in the lower atmosphere are the sources of excitation of acoustic gravity waves (AGWs). Fluctuations of atmospheric pressure within a wide range of frequencies, including infrasonic frequencies are evidence of these tropospheric wave sources. We simulate numerically the propagation of waves from tropospheric infrasound sources, and our study concerns the influences of these waves on the atmosphere. Numerical experiments have shown that the small-amplitude infrasound waves can propagate without striking manifestations up to the heights of about 100 km. Only waves propagating with a rather small angle to the vertical, penetrate the thermosphere and heat the thermosphere and generate internal gravity waves. Numerical experiments have revealed that tropospheric sources with spatial scales of several kilometers, are able to create wave disturbances in the thermosphere with spatial scales from tens to one thousand kilometers. The heating effect and generation of gravity waves is significant due to the fact that it accumulates. During one hour, the thermospheric temperature may change due to heating by infrasonic waves more than by 10 degrees. The simulations have shown that the infrasonic waves propagated upward may be a significant source of thermosphere heating.

  19. Effect of quantum correction on nonlinear thermal wave of electrons driven by laser heating

    NASA Astrophysics Data System (ADS)

    Nafari, F.; Ghoranneviss, M.

    2016-08-01

    In thermal interaction of laser pulse with a deuterium-tritium (DT) plane, the thermal waves of electrons are generated instantly. Since the thermal conductivity of electron is a nonlinear function of temperature, a nonlinear heat conduction equation is used to investigate the propagation of waves in solid DT. This paper presents a self-similar analytic solution for the nonlinear heat conduction equation in a planar geometry. The thickness of the target material is finite in numerical computation, and it is assumed that the laser energy is deposited at a finite initial thickness at the initial time which results in a finite temperature for electrons at initial time. Since the required temperature range for solid DT ignition is higher than the critical temperature which equals 35.9 eV, the effects of quantum correction in thermal conductivity should be considered. This letter investigates the effects of quantum correction on characteristic features of nonlinear thermal wave, including temperature, penetration depth, velocity, heat flux, and heating and cooling domains. Although this effect increases electron temperature and thermal flux, penetration depth and propagation velocity are smaller. This effect is also applied to re-evaluate the side-on laser ignition of uncompressed DT.

  20. Effects of the summer heat wave of 1988 on daily mortality in Allegheny County, PA.

    PubMed

    Ramlow, J M; Kuller, L H

    1990-01-01

    The authors studied total mortality in Allegheny County, PA, during the summer of 1988. A heat wave occurred in July of 1988, with daily maximum temperatures near or above 90 degrees Fahrenheit on 15 consecutive days. During that period there were a total of 694 deaths from all causes in the county, compared with an expected 587 deaths (P less than .01). All 107 excess deaths were of persons ages 65 or older, with the majority (78) occurring to persons older than age 75. Daily mortality was most closely correlated with average temperature from the previous day (R = .49, P less than .01), suggesting the cumulative effects of successive high daytime and night-time temperatures on susceptible persons. Evaluation of a possible effect on mortality of high ambient ozone levels detected in early July suggested that ozone did not contribute to excess mortality during the heat wave. Comparison of the 1988 heat wave with a less intense hot spell of 1973 indicated that excess mortality was less than would have been expected in 1988. The authors speculate that increased public awareness and the wider use of air conditioning over the years may have reduced the lethality of periods of extreme summer temperatures in urban areas. Further research is needed to evaluate this hypothesis completely. Public health officials should continue to monitor weather forecasts for predictions of extended periods of unusual heat and should warn the public to take suitable precautions during such periods. PMID:2113688

  1. Development and Testing of a Refractory Millimeter-Wave Absorbent Heat Exchanger

    NASA Technical Reports Server (NTRS)

    Lambot, Thomas; Myrabo, Leik; Murakami, David; Parkin, Kevin

    2014-01-01

    Central to the Millimeter-Wave Thermal Launch System (MTLS) is the millimeter-wave absorbent heat exchanger. We have developed metallic and ceramic variants, with the key challenge being the millimeter-wave absorbent coatings for each. The ceramic heat exchanger came to fruition first, demonstrating for the first time 1800 K peak surface temperatures under illumination by a 110 GHz Gaussian beam. Absorption efficiencies of up to 80 are calculated for mullite heat exchanger tubes and up to 50 are calculated for alumina tubes. These are compared with estimates based on stratified layer and finite element analyses. The problem of how to connect the 1800 K end of the ceramic tubes to a graphite outlet manifold and nozzle is solved by press fitting, or by threading the ends of the ceramic tubes and screwing them into place. The problem of how to connect the ceramic tubes to a metallic or nylon inlet pipe is solved by using soft compliant PTFE and PVC tubes that accommodate thermal deformations of the ceramic tubes during startup and operation. We show the resulting heat exchangers in static tests using argon and helium as propellants.

  2. Hybrid Model of Inhomogeneous Solar Wind Plasma Heating by Alfven Wave Spectrum: Parametric Studies

    NASA Technical Reports Server (NTRS)

    Ofman, L.

    2010-01-01

    Observations of the solar wind plasma at 0.3 AU and beyond show that a turbulent spectrum of magnetic fluctuations is present. Remote sensing observations of the corona indicate that heavy ions are hotter than protons and their temperature is anisotropic (T(sub perpindicular / T(sub parallel) >> 1). We study the heating and the acceleration of multi-ion plasma in the solar wind by a turbulent spectrum of Alfvenic fluctuations using a 2-D hybrid numerical model. In the hybrid model the protons and heavy ions are treated kinetically as particles, while the electrons are included as neutralizing background fluid. This is the first two-dimensional hybrid parametric study of the solar wind plasma that includes an input turbulent wave spectrum guided by observation with inhomogeneous background density. We also investigate the effects of He++ ion beams in the inhomogeneous background plasma density on the heating of the solar wind plasma. The 2-D hybrid model treats parallel and oblique waves, together with cross-field inhomogeneity, self-consistently. We investigate the parametric dependence of the perpendicular heating, and the temperature anisotropy in the H+-He++ solar wind plasma. It was found that the scaling of the magnetic fluctuations power spectrum steepens in the higher-density regions, and the heating is channeled to these regions from the surrounding lower-density plasma due to wave refraction. The model parameters are applicable to the expected solar wind conditions at about 10 solar radii.

  3. Monitoring the Impact of Heat Waves with Emergency Service Utilization Data in Los Angeles County

    PubMed Central

    Kajita, Emily; Araki, Patricia; Luarca, Monica; Hwang, Bessie

    2013-01-01

    Objective To assess current indicators for situational awareness during heat waves derived from electronic emergency department (ED) and 911 emergency dispatch call (EDC) center data. Introduction Los Angeles County’s (LAC) early event detection system captures over 60% of total ED visits, as well as 800 to 1,000 emergency dispatch calls from Los Angeles City Fire (LACF) daily. Both ED visits and EDC calls are classified into syndrome categories, and then analyzed for aberrations in count and spatial distribution. During periods of high temperatures, a heat report is generated and sent to stakeholders upon request. We describe how syndromic surveillance serves as an important near real-time, population-based instrument for measuring the impact of heat waves on emergency service utilization in LAC. Methods Daily electronic ED registration data, EDC calls, and high temperatures from Palmdale, California were queried from January 1, 2010 to August 26, 2012 and aggregated into Centers for Disease Control (CDC) weeks. A custom “heat exposure” category was created by searching ED chief complaints for key terms such as “Heat stroke,” “hyperthermia,” “overheat,” and relevant ICD9 diagnosis codes. Similarly, EDC calls were classified if related to “heat exposure.” Pearson correlation tests were used to determine correlation between total ED visits, heat-related ED visits, heat-related EDC calls, and daily maximum temperatures. Results Thus far 2012 has exceeded counts cumulative to August 26th for the past two years in the number of heat-related ED visits, heat-related EDC calls, and hot days (Table 1). In particular, the number of 105 degree-and-up days this year has already doubled what was observed all year during 2010 and 2011. Age groups were similarly distributed in total ED visits, heat-related ED visits and EDC calls, with a 18 to 44 year old majority (37%, 37%, and 42% respectively), followed by 45 to 64 year olds (23%, 21%, 23%). Total ED

  4. Heat waves observed in 2007 in Athens, Greece: synoptic conditions, bioclimatological assessment, air quality levels and health effects.

    PubMed

    Theoharatos, George; Pantavou, Katerina; Mavrakis, Anastasios; Spanou, Anastasia; Katavoutas, George; Efstathiou, Panos; Mpekas, Periklis; Asimakopoulos, Dimosthenis

    2010-02-01

    Heat waves are considered to be increasing in frequency and intensity whereas they comprise a significant weather-related cause of deaths in several countries. Two heat waves occurred in Greece in summer 2007. These severe heat waves are assessed by analyzing the prevailing synoptic conditions, evaluating human thermal discomfort, through the Heat Load Index (HL), as well as investigating its interrelation of air pollutant concentrations, and the daily air quality stress index (AQSI), in the greater region of Athens (Attica), Greece. Furthermore, the relation of HL values and the number of heatstroke and heat exhaustion events recorded in public hospitals operating within the Greek National Health System is examined. Data included radiosonde measurements from the Athens airport station (LGAT), NCEP/NCAR reanalysis data in order to obtain the position of the Subtropical Jet Stream (STJ), GDAS meteorological data for back-trajectory calculation, 10-min meteorological data from 10 Hydro-Meteorological stations and mean hourly values of nitric dioxide (NO(2)), sulphur dioxide (SO(2)) and ozone (O(3)) concentrations, measured at 7 different sites, for the last 10-day period of June and July 2007. Spearman's rank correlation test was used to observe any possible correlation between HL values and air pollutant concentrations, and AQSI values. The results demonstrated different synoptic characteristics for the heat waves of June and July. In the heat wave of June, higher ambient temperatures were recorded and greater HL values were calculated. Extreme discomfort conditions were identified in both heat waves during both day-time and night-time hours. The air pollution analysis showed poor air quality conditions for the heat wave of July, while a significant correlation was found between HL values and average hourly concentrations of O(3), NO(2) and SO(2). The number of heat-affected patients reported during the June heat wave was larger. PMID:20060520

  5. Heat waves observed in 2007 in Athens, Greece: synoptic conditions, bioclimatological assessment, air quality levels and health effects.

    PubMed

    Theoharatos, George; Pantavou, Katerina; Mavrakis, Anastasios; Spanou, Anastasia; Katavoutas, George; Efstathiou, Panos; Mpekas, Periklis; Asimakopoulos, Dimosthenis

    2010-02-01

    Heat waves are considered to be increasing in frequency and intensity whereas they comprise a significant weather-related cause of deaths in several countries. Two heat waves occurred in Greece in summer 2007. These severe heat waves are assessed by analyzing the prevailing synoptic conditions, evaluating human thermal discomfort, through the Heat Load Index (HL), as well as investigating its interrelation of air pollutant concentrations, and the daily air quality stress index (AQSI), in the greater region of Athens (Attica), Greece. Furthermore, the relation of HL values and the number of heatstroke and heat exhaustion events recorded in public hospitals operating within the Greek National Health System is examined. Data included radiosonde measurements from the Athens airport station (LGAT), NCEP/NCAR reanalysis data in order to obtain the position of the Subtropical Jet Stream (STJ), GDAS meteorological data for back-trajectory calculation, 10-min meteorological data from 10 Hydro-Meteorological stations and mean hourly values of nitric dioxide (NO(2)), sulphur dioxide (SO(2)) and ozone (O(3)) concentrations, measured at 7 different sites, for the last 10-day period of June and July 2007. Spearman's rank correlation test was used to observe any possible correlation between HL values and air pollutant concentrations, and AQSI values. The results demonstrated different synoptic characteristics for the heat waves of June and July. In the heat wave of June, higher ambient temperatures were recorded and greater HL values were calculated. Extreme discomfort conditions were identified in both heat waves during both day-time and night-time hours. The air pollution analysis showed poor air quality conditions for the heat wave of July, while a significant correlation was found between HL values and average hourly concentrations of O(3), NO(2) and SO(2). The number of heat-affected patients reported during the June heat wave was larger.

  6. Polarization of ELF waves generated during "beat-wave" heating experiment near cutoff frequency of the Earth-ionosphere waveguide

    NASA Astrophysics Data System (ADS)

    Fedorenko, Yu.; Tereshchenko, E.; Pilgaev, S.; Grigoryev, V.; Blagoveshchenskaya, N.

    2014-12-01

    High-frequency heating of the ionosphere is effective for generating extremely low frequencies (ELF, 3-3000 Hz) through modulation of the auroral electrojet current. While the amplitudes of the resulting ELF waves depend on the auroral electrojet current strength, the polarization of their horizontal magnetic field remains relatively stable. In this work, we determined that at the distance of several wavelengths from an ionospheric ELF source created by two HF heating waves separated by an ELF frequency, polarization parameters are influenced by the Earth-ionosphere waveguide. Previous experiments in the vicinity of the ionospheric ELF source have determined that the right-hand polarization of the magnetic field measured at the ground typically prevails, whereas in this paper we demonstrate that at the distance of 660 km to the east of the European Incoherent Scatter, a circular left-hand polarization dominates. We interpret this effect as a result of "trapping" of the left-hand mode between the upper and lower boundaries of the Earth-ionosphere waveguide, while the right-hand or whistler mode leaks into the ionosphere.

  7. Changes in cause-specific mortality during heat waves in central Spain, 1975-2008

    NASA Astrophysics Data System (ADS)

    Miron, Isidro Juan; Linares, Cristina; Montero, Juan Carlos; Criado-Alvarez, Juan Jose; Díaz, Julio

    2015-09-01

    The relationship between heat waves and mortality has been widely described, but there are few studies using long daily data on specific-cause mortality. This study is undertaken in central Spain and analysing natural causes, circulatory and respiratory causes of mortality from 1975 to 2008. Time-series analysis was performed using ARIMA models, including data on specific-cause mortality and maximum and mean daily temperature and mean daily air pressure. The length of heat waves and their chronological number were analysed. Data were stratified in three decadal stages: 1975-1985, 1986-1996 and 1997-2008. Heat-related mortality was triggered by a threshold temperature of 37 °C. For each degree that the daily maximum temperature exceeded 37 °C, the percentage increase in mortality due to circulatory causes was 19.3 % (17.3-21.3) in 1975-1985, 30.3 % (28.3-32.3) in 1986-1996 and 7.3 % (6.2-8.4) in 1997-2008. The increase in respiratory cause ranged from 12.4 % (7.8-17.0) in the first period, to 16.3 % (14.1-18.4) in the second and 13.7 % (11.5-15.9) in the last. Each day of heat-wave duration explained 5.3 % (2.6-8.0) increase in respiratory mortality in the first period and 2.3 % (1.6-3.0) in the last. Decadal scale differences exist for specific-causes mortality induced by extreme heat. The impact on heat-related mortality by natural and circulatory causes increases between the first and the second period and falls significantly in the last. For respiratory causes, the increase is no reduced in the last period. These results are of particular importance for the estimation of future impacts of climate change on health.

  8. Evaporation and Accompanying Isotopic Fractionation of Sulfur from FE-S Melt During Shock Wave Heating

    NASA Technical Reports Server (NTRS)

    Tachibana, S.; Huss, G. R.; Miura, H.; Nakamoto, T.

    2004-01-01

    Chondrules probably formed by melting and subsequent cooling of solid precursors. Evaporation during chondrule melting may have resulted in depletion of volatile elements in chondrules. It is known that kinetic evaporation, especially evaporation from a melt, often leads to enrichment of heavy isotopes in an evaporation residue. However, no evidence for a large degree of heavy-isotope enrichment has been reported in chondrules for K, Mg, Si, and Fe (as FeO). The lack of isotopic fractionation has also been found for sulfur in troilites (FeS) within Bishunpur (LL3.1) and Semarkona (LL3.0) chondrules by an ion microprobe study. The largest fractionation, found in only one grain, was 2.7 +/- 1.4 %/amu, while all other troilite grains showed isotopic fractionations of <1 %/amu. The suppressed isotopic fractionation has been interpreted as results of (i) rapid heating of precursors at temperatures below the silicate solidus and (ii) diffusion-controlled evaporation through a surrounding silicate melt at temperatures above the silicate solidus. The kinetic evaporation model suggests that a rapid heating rate of >10(exp 4)-10(exp 6) K/h for a temperature range of 1000-1300 C is required to explain observed isotopic fractionations. Such a rapid heating rate seems to be difficult to be achieved in the X-wind model, but can be achieved in shock wave heating models. In this study, we have applied the sulfur evaporation model to the shock wave heating conditions of to evaluate evaporation of sulfur and accompanying isotopic fractionation during shock wave heating at temperatures below the silicate solidus.

  9. Using NASA Earth Science Datasets for National Climate Assessment Indicators: Urban Impacts of Heat Waves Associated with Climate Change

    NASA Astrophysics Data System (ADS)

    Sadoff, N.; Weber, S.; Zell, E. R.; de Sherbinin, A. M.

    2014-12-01

    Climate-induced heat waves have been increasing globally in the past 5-10 years and are projected to continue increasing throughout the 21st century. In urban areas, heat waves are exacerbated by the non-climate stressor of urban heat islands (UHIs). The vulnerability of a city's population to heat waves reflects exposure to extreme heat events, sensitivity of the population to impacts, such as adverse health effects, and adaptive capacity to prepare for and respond to heat waves. Socially and economically vulnerable populations are especially at risk to the impacts of heat waves, due to increasing energy costs, air pollution, and heat-related illness and mortality. NASA earth science datasets, combined with socioeconomic data, can be used to create indicators that characterize vulnerability to urban heat events and address the effectiveness of adaptation measures designed to reduce local temperatures. The indicator development process should include engagement from local stakeholders and end users from the onset to ensure local relevance and, ultimately, indicator uptake and sustainability. This presentation will explore the process of working with urban stakeholders in Philadelphia to develop a set of policy-relevant, interdisciplinary vulnerability indicators focused on extreme heat events in urban areas. Ambient and land surface temperature, land cover classifications, NDVI, and US Census data are used to create a basket of indicators that reflect urban heat wave duration and intensity, UHI exposure, socioeconomic vulnerability, and adaptation effectiveness. These indicators can be assessed at the city level and also comparatively among different parts of a city to help quantify and track heat wave impacts on vulnerable populations and the effectiveness of adaptation measures.

  10. Numerical study of shock wave interaction in steady flows of a viscous heat-conducting gas with a low ratio of specific heats

    NASA Astrophysics Data System (ADS)

    Shoev, G. V.; Ivanov, M. S.

    2016-05-01

    Specific features of shock wave interaction in a viscous heat-conducting gas with a low ratio of specific heats are numerically studied. The case of the Mach reflection of shock waves with a negative angle of the reflected wave with respect to the free-stream velocity vector is considered, and the influence of viscosity on the flow structure is analyzed. Various issues of nonuniqueness of the shock wave configuration for different Reynolds numbers are discussed. Depending on the initial conditions and Reynolds numbers, two different shock wave configurations may exist: regular configuration interacting with an expansion fan and Mach configuration. In the dual solution domain, a possibility of the transition from regular to the Mach reflection of shock waves is considered.

  11. Precipitation of sword bean proteins by heating and addition of magnesium chloride in a crude extract.

    PubMed

    Nishizawa, Kaho; Masuda, Tetsuya; Takenaka, Yasuyuki; Masui, Hironori; Tani, Fumito; Arii, Yasuhiro

    2016-08-01

    Sword bean (Canavalia gladiata) seeds are a traditional food in Asian countries. In this study, we aimed to determine the optimal methods for the precipitation of sword bean proteins useful for the food development. The soaking time for sword beans was determined by comparing it with that for soybeans. Sword bean proteins were extracted from dried seeds in distilled water using novel methods. We found that most proteins could be precipitated by heating the extract at more than 90 °C. Interestingly, adding magnesium chloride to the extract at lower temperatures induced specific precipitation of a single protein with a molecular weight of approximately 48 kDa. The molecular weight and N-terminal sequence of the precipitated protein was identical to that of canavalin. These data suggested that canavalin was precipitated by the addition of magnesium chloride to the extract. Our results provide important insights into the production of processed foods from sword bean.

  12. Heat transfer measurements and CFD comparison of swept shock wave/boundary-layer interactions

    NASA Technical Reports Server (NTRS)

    Lee, Y.; Settles, G. S.; Horstman, C. C.

    1992-01-01

    An experimental research program providing basic knowledge and establishing new data on the heat transfer in swept shock wave/boundary-layer interactions is described. An equilibrium turbulent boundary-layer on a flat plate is subjected to impingement by swept planar shock waves generated by a sharp fin. Five different interactions with fin angles ranging from 10 to 20 deg at freestream Mach numbers of 3.0 and 4.0 produce a variety of interaction strengths from weak to very strong. A foil heater generates a uniform heat flux over the flat plate surface and miniature thin-film-resistance sensors mounted on it are used to measure the local surface temperature. The heat convection equation is then solved for the heat transfer distribution within an interaction, yielding a total uncertainty of about +/- 10 percent. These experimental data are compared with the results of numerical Navier-Stokes solutions which employ a kappa-epsilon turbulence model. Finally, a simplified form of the peak heat transfer correlation for fin interactions is suggested.

  13. Low-frequency waves and ion heating associated with double layers in the downward current region of the auroral ionosphere

    NASA Astrophysics Data System (ADS)

    Sen, Naresh

    2009-06-01

    Recent observations by satellites in the auroral ionosphere have established the presence of strong narrowly localized electric fields parallel to the ambient magnetic field. Physically these fields are formed by two layers of opposite charges in close proximity existing self-consistently in the plasma; this is known as a double layer (DL). The DL field accelerates plasma particles to form beams which excite wave modes and saturate to form electron phase-space holes (EHs). Intense perpendicular heating of ions is concurrently observed, leading to speculations regarding the heating mechanism(s). In this thesis, we address this issue via numerical simulations and analysis. We have performed electrostatic kinetic simulations using the Vlasov-Poisson system of equations for conditions prevalent in the downward current region (DCR) of the auroral ionosphere. The simulations display low-frequency waves, EHs and ion heating, consistent with observations. We determine the relative importance of two proposed mechanisms for ion heating: stochastic heating due to EHs and due to wave-particle interactions at identifiable wave modes. Stochastic heating of ions via EH-ion scattering is estimated to account for approximately 10-15% of the observed increase in ion temperature in regions of intense wave activity. Spectral analysis shows that the energy exchange between waves and ions is concentrated at frequencies and wave numbers associated with nearly perpendicular magnetized ion wave modes and not EHs. We conclude that, in the vicinity of DLs in the DCR of the auroral ionosphere where both intense waves and EHs are present, wave-particle interactions are the principal mechanism of ion heating, with stochastic heating by electron phase-space holes playing a minor role.

  14. Overly persistent circulation in climate models contributes to overestimated frequency and duration of heat waves and cold spells

    NASA Astrophysics Data System (ADS)

    Plavcová, Eva; Kyselý, Jan

    2016-05-01

    The study examines links of summer heat waves and winter cold spells in Central Europe to atmospheric circulation and specifically its persistence in an ensemble of regional climate models (RCMs). We analyse 13 RCMs driven by the ERA-40 reanalysis and compare them against observations over reference period 1971-2000. Using objective classification of circulation types and an efficiency coefficient with a block resampling test, we identify circulation types significantly conducive to heat waves and cold spells. We show that the RCMs have a stronger tendency to group together days with very high or low temperature and tend to simulate too many heat waves and cold spells, especially those lasting 5 days and more. Circulation types conducive to heat waves in summer are characterized by anticyclonic, southerly and easterly flow, with increasing importance of warm advection during heat waves. Winter cold spells are typically associated with easterly and anticyclonic flow, and the onset of cold spells tends to be linked to northerly and cyclonic flow with cold advection. The RCMs are generally able to reproduce the links between circulation and heat waves or cold spells, including the radiation-to-advection effect for heat waves and the opposite advection-to-radiation effect for cold spells. They capture relatively well also changes of mean temperature anomalies during sequences of given circulation types, namely the tendency towards temperature increase (decrease) during those types conducive to heat waves (cold spells). Since mean lengths of all circulation supertypes are overestimated in the RCMs, we conclude that the overly persistent circulation in climate models contributes to the overestimated frequency of long heat waves and cold spells. As these biases are rather general among the examined RCMs and similar drawbacks are likely to be manifested in climate model simulations for the twenty-first century, the results also suggest that climate change scenarios for

  15. Gravity wave forcing in the middle atmosphere due to reduced ozone heating during a solar eclipse

    NASA Technical Reports Server (NTRS)

    Fritts, David C.; Luo, Zhangai

    1993-01-01

    We present an analysis of the gravity wave structure and the associated forcing of the middle atmosphere induced by the screening of the ozone layer from solar heating during a solar eclipse. Fourier integral techniques and numerical evaluation of the integral solutions were used to assess the wave field structure and to compute the gravity wave forcing of the atmosphere at greater heights. Our solutions reveal dominant periods of a few hours, characteristic horizontal and vertical scales of about 5000 to 10,000 km and 200 km, respectively, and an integrated momentum flux in the direction of eclipse motion of about 5.6 x 10 exp 8 N at each height above the forcing level. These results suggest that responses to solar eclipses may be difficult to detect above background gravity wave and tidal fluctuations until well into the thermosphere. Conversely, the induced body forces may penetrate to considerable heights because of the large wave scales and will have significant effects at levels where the wave field is dissipated.

  16. Nonlinear feedback in a six-dimensional Lorenz model: impact of an additional heating term

    NASA Astrophysics Data System (ADS)

    Shen, B.-W.

    2015-12-01

    In this study, a six-dimensional Lorenz model (6DLM) is derived, based on a recent study using a five-dimensional (5-D) Lorenz model (LM), in order to examine the impact of an additional mode and its accompanying heating term on solution stability. The new mode added to improve the representation of the streamfunction is referred to as a secondary streamfunction mode, while the two additional modes, which appear in both the 6DLM and 5DLM but not in the original LM, are referred to as secondary temperature modes. Two energy conservation relationships of the 6DLM are first derived in the dissipationless limit. The impact of three additional modes on solution stability is examined by comparing numerical solutions and ensemble Lyapunov exponents of the 6DLM and 5DLM as well as the original LM. For the onset of chaos, the critical value of the normalized Rayleigh number (rc) is determined to be 41.1. The critical value is larger than that in the 3DLM (rc ~ 24.74), but slightly smaller than the one in the 5DLM (rc ~ 42.9). A stability analysis and numerical experiments obtained using generalized LMs, with or without simplifications, suggest the following: (1) negative nonlinear feedback in association with the secondary temperature modes, as first identified using the 5DLM, plays a dominant role in providing feedback for improving the solution's stability of the 6DLM, (2) the additional heating term in association with the secondary streamfunction mode may destabilize the solution, and (3) overall feedback due to the secondary streamfunction mode is much smaller than the feedback due to the secondary temperature modes; therefore, the critical Rayleigh number of the 6DLM is comparable to that of the 5DLM. The 5DLM and 6DLM collectively suggest different roles for small-scale processes (i.e., stabilization vs. destabilization), consistent with the following statement by Lorenz (1972): "If the flap of a butterfly's wings can be instrumental in generating a tornado, it can

  17. Nonlinear feedback in a six-dimensional Lorenz Model: impact of an additional heating term

    NASA Astrophysics Data System (ADS)

    Shen, B.-W.

    2015-03-01

    In this study, a six-dimensional Lorenz model (6DLM) is derived, based on a recent study using a five-dimensional (5-D) Lorenz model (LM), in order to examine the impact of an additional mode and its accompanying heating term on solution stability. The new mode added to improve the representation of the steamfunction is referred to as a secondary streamfunction mode, while the two additional modes, that appear in both the 6DLM and 5DLM but not in the original LM, are referred to as secondary temperature modes. Two energy conservation relationships of the 6DLM are first derived in the dissipationless limit. The impact of three additional modes on solution stability is examined by comparing numerical solutions and ensemble Lyapunov exponents of the 6DLM and 5DLM as well as the original LM. For the onset of chaos, the critical value of the normalized Rayleigh number (rc) is determined to be 41.1. The critical value is larger than that in the 3DLM (rc ~ 24.74), but slightly smaller than the one in the 5DLM (rc ~ 42.9). A stability analysis and numerical experiments obtained using generalized LMs, with or without simplifications, suggest the following: (1) negative nonlinear feedback in association with the secondary temperature modes, as first identified using the 5DLM, plays a dominant role in providing feedback for improving the solution's stability of the 6DLM, (2) the additional heating term in association with the secondary streamfunction mode may destabilize the solution, and (3) overall feedback due to the secondary streamfunction mode is much smaller than the feedback due to the secondary temperature modes; therefore, the critical Rayleigh number of the 6DLM is comparable to that of the 5DLM. The 5DLM and 6DLM collectively suggest different roles for small-scale processes (i.e., stabilization vs. destabilization), consistent with the following statement by Lorenz (1972): If the flap of a butterfly's wings can be instrumental in generating a tornado, it can

  18. Effect of heat wave at the initial stage in spark plasma sintering.

    PubMed

    Zhang, Long; Zhang, Xiaomin; Chu, Zhongxiang; Peng, Song; Yan, Zimin; Liang, Yuan

    2016-01-01

    Thermal effects are important considerations at the initial stage in spark plasma sintering of non-conductive Al2O3 powders. The generalized thermo-elastic theory is introduced to describe the influence of the heat transport and thermal focusing caused by thermal wave propagation within a constrained space and transient time. Simulations show that low sintering temperature can realize high local temperature because of the superposition effect of heat waves. Thus, vacancy concentration differences between the sink and the cross section of the particles increase relative to that observed during pressure-less and hot-pressure sintering. Results show that vacancy concentration differences are significantly improved during spark plasma sintering, thereby decreasing the time required for sintering. PMID:27386287

  19. Mortality in 13 French cities during the August 2003 heat wave.

    PubMed

    Vandentorren, Stéphanie; Suzan, Florence; Medina, Sylvia; Pascal, Mathilde; Maulpoix, Adeline; Cohen, Jean-Claude; Ledrans, Martine

    2004-09-01

    We observed the daily trend in mortality rates during the 2003 heat wave in 13 of France's largest cities. Mortality data were collected from July 25 to September 15 each year from 1999 through 2003. The conjunction of a maximum temperature of 35 degrees C and a minimum temperature of 20 degrees C was exceptional in 7 cities. An excess mortality rate was observed in the 13 towns, with disparities from +4% (Lille) to +142% (Paris). PMID:15333306

  20. General and specific mortality among the elderly during the 2003 heat wave in Genoa (Italy).

    PubMed

    Conti, Susanna; Masocco, Maria; Meli, Paola; Minelli, Giada; Palummeri, Ernesto; Solimini, Renata; Toccaceli, Virgilia; Vichi, Monica

    2007-02-01

    The effects of heat waves on health can be serious for elderly persons, especially those in urban areas. We investigated in-depth the mortality excess during the 2003 heat wave among elderly persons (>74 years) in the City of Genoa (Italy). The excess in general mortality was calculated for the period July 16-August 31, as the ratio of observed to expected deaths. To evaluate "harvesting", we compared observed and expected mortality in the period September 2003-April 2004. We also studied the relationship between mortality and climatic conditions considering daily maximum temperature and Humidex discomfort degrees, as well as "lag-time". For cause-specific mortality, we considered all pathologies reported on the death certificate. The excess in general mortality was significant and was greatest in the first half of August. During Summer 2003, in Genoa the climatic conditions (described in terms of maximum temperature and Humidex Index) were extremely hot; regarding lag-time, the greatest correlation between the number of observed deaths and the maximum temperature values was observed for the three preceding days (rho=0.568; significance level<0.01). The prominent causes of death, for which an excess was observed, were cerebrovascular diseases, severe respiratory diseases, severe renal diseases, dementia; moreover, certain pathologic conditions and symptoms, usually not lethal, were also frequent causes of death (e.g., hypovolemia, hyperpyrexia, decubitus ulcers and immobilization syndrome). The results of this study confirm the relationship between the heat waves and death among elderly, stressing that, because of their poorer physical health and the prevalence of cognitive disturbances that hinder risk perception, it is necessary to properly care for them during heat waves. PMID:16890219

  1. The time development of a blast wave with shock heated electrons

    NASA Technical Reports Server (NTRS)

    Edgar, R. J.; Cox, D. P.

    1983-01-01

    Accurate approximations are presented for the time development of both edge conditions and internal structures of a blast wave with shock heated electrons, and equal ion and electron temperatures at the shock. The cases considered evolve in cavities with power law ambient densities (including the uniform ambient density case) and have negligible external pressure. Account is taken of possible saturation of the thermal conduction flux. The structures evolve smoothly to the adiabatic structures.

  2. The time development of a blast wave with shock-heated electrons

    NASA Technical Reports Server (NTRS)

    Edgar, R. J.; Cox, D. P.

    1984-01-01

    Accurate approximations are presented for the time development of both edge conditions and internal structures of a blast wave with shock heated electrons, and equal ion and electron temperatures at the shock. The cases considered evolve in cavities with power law ambient densities (including the uniform ambient density case) and have negligible external pressure. Account is taken of possible saturation of the thermal conduction flux. The structures evolve smoothly to the adiabatic structures.

  3. A new mechanism for excitation of electrostatic ion cyclotron waves and associated perpendicular ion heating

    NASA Technical Reports Server (NTRS)

    Ganguli, G.; Lee, Y. C.; Palmadesso, P.

    1985-01-01

    A new mechanism for exciting the kinetic ion cyclotron waves in the presence of a nonuniform electric field perpendicular to the external magnetic field is given. Application of this instability to various space plasmas is discussed. The new instability mechanism may provide a more efficient agent for perpendicular ion heating than other EIC generation processes, since the linear growth rate is insensitive to the temperature ratio.

  4. Edge Ion Heating by Launched High Harmonic Fast Waves in NSTX

    SciTech Connect

    T.M. Biewer; R.E. Bell; S.J. Diem; C.K. Phillips; J.R. Wilson; P.M. Ryan

    2004-12-01

    A new spectroscopic diagnostic on the National Spherical Torus Experiment (NSTX) measures the velocity distribution of ions in the plasma edge simultaneously along both poloidal and toroidal views. An anisotropic ion temperature is measured during high-power high harmonic fast wave (HHFW) radio-frequency (rf) heating in helium plasmas, with the poloidal ion temperature roughly twice the toroidal ion temperature. Moreover, the measured spectral distribution suggests that two populations of ions are present and have temperatures of typically 500 eV and 50 eV with rotation velocities of -50 km/s and -10 km/s, respectively (predominantly perpendicular to the local magnetic field). This bi-modal distribution is observed in both the toroidal and poloidal views (for both He{sup +} and C{sup 2+} ions), and is well correlated with the period of rf power application to the plasma. The temperature of the hot component is observed to increase with the applied rf power, which was scanned between 0 and 4.3 MW . The 30 MHz HHFW launched by the NSTX antenna is expected and observed to heat core electrons, but plasma ions do not resonate with the launched wave, which is typically at >10th harmonic of the ion cyclotron frequency in the region of observation. A likely ion heating mechanism is parametric decay of the launched HHFW into an Ion Bernstein Wave (IBW). The presence of the IBW in NSTX plasmas during HHFW application has been directly confirmed with probe measurements. IBW heating occurs in the perpendicular ion distribution, consistent with the toroidal and poloidal observations. Calculations of IBW propagation indicate that multiple waves could be created in the parametric decay process, and that most of the IBW power would be absorbed in the outer 10 to 20 cm of the plasma, predominantly on fully stripped ions. These predictions are in qualitative agreement with the observations, and must be accounted for when calculating the energy budget of the plasma.

  5. Heating of the Partially Ionized Solar Chromosphere by Waves in Magnetic Structures

    NASA Astrophysics Data System (ADS)

    Shelyag, S.; Khomenko, E.; de Vicente, A.; Przybylski, D.

    2016-03-01

    In this paper, we show a “proof of concept” of the heating mechanism of the solar chromosphere due to wave dissipation caused by the effects of partial ionization. Numerical modeling of non-linear wave propagation in a magnetic flux tube, embedded in the solar atmosphere, is performed by solving a system of single-fluid quasi-MHD equations, which take into account the ambipolar term from the generalized Ohm’s law. It is shown that perturbations caused by magnetic waves can be effectively dissipated due to ambipolar diffusion. The energy input by this mechanism is continuous and shown to be more efficient than dissipation of static currents, ultimately leading to chromospheric temperature increase in magnetic structures.

  6. Co-counter asymmetry in fast wave heating and current drive

    SciTech Connect

    Jaeger, E.F.; Carter, M.D.; Berry, L.A.; Batchelor, D.B.; Forest, C.B.; Weitzner, H.

    1997-04-01

    Full wave ICRF coupling models show differences in plasma response when antenna arrays are phase to drive currents and counter to the plasma current. The source of this difference lies in the natural up- sown asymmetry of the antenna`s radiated power spectrum. This asymmetry is due to Hall terms in the wave equation, and occurs even without a poloidal magnetic field. When a poloidal field is included, the up-down asymmetry acquires a toroidal component. The result is that plasma absorption (i.e. antenna loading) is shifted or skewed toward the co-current drive direction, independent of the direction of the magnetic field. When wave are launched to drive current counter the plasma current , electron heating an current profiles are more peaked on axis, and this peaking becomes more pronounce a lower toroidal magnetic fields.

  7. Additions to compact heat exchanger technology: Jet impingement cooling & flow & heat transfer in metal foam-fins

    NASA Astrophysics Data System (ADS)

    Onstad, Andrew J.

    Compact heat exchangers have been designed following the same basic methodology for over fifty years. However, with the present emphasis on energy efficiency and light weight of prime movers there is increasing demand for completely new heat exchangers. Moreover, new materials and mesoscale fabrication technologies offer the possibility of significantly improving heat exchanger performance over conventional designs. This work involves fundamental flow and heat transfer experimentation to explore two new heat exchange systems: in Part I, large arrays of impinging jets with local extraction and in Part II, metal foams used as fins. Jet impingement cooling is widely used in applications ranging from paper manufacturing to the cooling of gas turbine blades because of the very high local heat transfer coefficients that are possible. While the use of single jet impingement results in non-uniform cooling, increased and more uniform mean heat transfer coefficients may be attained by dividing the total cooling flow among an array of smaller jets. Unfortunately, when the spent fluid from the array's central jets interact with the outer jets, the overall mean heat transfer coefficient is reduced. This problem can be alleviated by locally extracting the spent fluid before it is able to interact with the surrounding jets. An experimental investigation was carried out on a compact impingement array (Xn/Djet = 2.34) utilizing local extraction of the spent fluid (Aspent/Ajet = 2.23) from the jet exit plane. Spatially resolved measurements of the mean velocity field within the array were carried out at jet Reynolds numbers of 2300 and 5300 by magnetic resonance velocimetry, MRV. The geometry provided for a smooth transition from the jet to the target surface and out through the extraction holes without obvious flow recirculation. Mean Nusselt number measurements were also carried out for a Reynolds number range of 2000 to 10,000. The Nusselt number was found to increase with the

  8. Cool Roofs in Guangzhou, China: Outdoor Air Temperature Reductions during Heat Waves and Typical Summer Conditions.

    PubMed

    Cao, Meichun; Rosado, Pablo; Lin, Zhaohui; Levinson, Ronnen; Millstein, Dev

    2015-12-15

    In this paper, we simulate temperature reductions during heat-wave events and during typical summer conditions from the installation of highly reflective "cool" roofs in the Chinese megacity of Guangzhou. We simulate temperature reductions during six of the strongest historical heat-wave events over the past decade, finding average urban midday temperature reductions of 1.2 °C. In comparison, we simulate 25 typical summer weeks between 2004 and 2008, finding average urban midday temperature reductions of 0.8 °C, indicating that air temperature sensitivity to urban albedo in Guangzhou varies with meteorological conditions. We find that roughly three-fourths of the variance in air temperature reductions across all episodes can be accounted for by a linear regression, including only three basic properties related to the meteorological conditions: mean daytime temperature, humidity, and ventilation to the greater Guangzhou urban area. While these results highlight the potential for cool roofs to mitigate peak temperatures during heat waves, the temperature reductions reported here are based on the upper bound case, which increases albedos of all roofs (but does not modify road albedo or wall albedo).

  9. Gravity Wave and Turbulence Transport of Heat and Na in the Mesopause Region over the Andes

    NASA Astrophysics Data System (ADS)

    Guo, Yafang; Liu, Alan Z.

    2016-07-01

    The vertical heat and Na fluxes induced by gravity waves and turbulence are derived based on over 600 hours of observations from the Na wind/temperature lidar located at Andes lidar Observatory (ALO), Cerro Pachón, Chile. In the 85-100 km region, the annual mean vertical fluxes by gravity waves show downward heat transport with a maximum of 0.78K m/s at 90 km, and downward Na transport with a maximum of 210 m/s/cm3 at 94km. The maximum cooing rate reaches -24 K/d at 94km. The vertical fluxes have strong seasonal variations, with large differences in magnitudes and altitudes of maximum fluxes between winter and summer. The vertical fluxes due to turbulence eddies are also derived with a novel method that relates turbulence fluctuations of temperature and vertical wind with photon count fluctuations at very high resolution (25 m, 6 s). The results show that the vertical transports are comparable to those by gravity waves and they both play significant roles in the atmospheric thermal structure and constituent distribution. This direct measure of turbulence transport also enables estimate of the eddy diffusivity for heat and constituent in the mesopause region.

  10. Strong negative effects of simulated heat waves in a tropical butterfly.

    PubMed

    Fischer, Klaus; Klockmann, Michael; Reim, Elisabeth

    2014-08-15

    Climate change poses a significant challenge to all natural systems on Earth. Especially increases in extreme weather events such as heat waves have the potential to strongly affect biodiversity, though their effects are poorly understood because of a lack of empirical data. Therefore, we here explore the sensitivity of a tropical ectotherm, which are in general believed to have a low warming tolerance, to experimentally simulated climate change using ecologically realistic diurnal temperature cycles. Increasing the mean temperature permanently by 3°C had mostly minor effects on developmental traits in the butterfly Bicyclus anynana. Simulated heat waves (strongly elevated temperatures for some time though retaining the same overall temperature mean), in contrast, caused strong negative effects by prolonging development time (by up to 10%) and reducing body mass (-21%), especially when combined with reduced relative humidity. Detrimental effects were carried over into the adult stage, diminishing subsequent performance. Most strikingly, higher temperatures suppressed adult immune function (haemocytes: -54%, lysozyme activity: -32%), which may potentially change the way species interact with antagonists. Heat waves thus reduced fitness parameters by 10-25% for development time and body mass and by up to 54% for immune parameters even in this plastic and widespread butterfly, exemplifying the potentially dramatic impact of extreme weather events on biodiversity.

  11. Simulation of High Power ICRF Wave Heating in the ITER Burning Plasma

    NASA Astrophysics Data System (ADS)

    Jaeger, E. F.; Berry, L. A.; Barrett, R. F.; D'Azevedo, E. F.

    2007-11-01

    ITER relies on Ion-cyclotron Radio Frequency (ICRF) power to heat the plasma to fusion temperatures. To heat effectively, the waves must couple efficiently to the core plasma. Recent simulations using AORSA [1] on the 120 TF Cray XT-4 (Jaguar) at ORNL show that the waves propagate radially inward and are rapidly absorbed with little heating of the plasma edge. AORSA has achieved 87.5 trillion calculations per second (87.5 teraflops) on Jaguar, which is 73 percent of the system's theoretical peak. Three dimensional visualizations show ``hot spots'' near the antenna surface where the wave amplitude is high. AORSA simulations are also being used to study how to best use ICRF to drive plasma currents for optimizing ITER performance and pulse length. Results for Scenario 4 show a maximum current of 0.54 MA for 20 MW of power at 57 MHz. [1] E.F. Jaeger, L.A. Berry, E. D'Azevedo, et al., Phys. Plasmas. 8, 1573 (2001).

  12. Cool Roofs in Guangzhou, China: Outdoor Air Temperature Reductions during Heat Waves and Typical Summer Conditions.

    PubMed

    Cao, Meichun; Rosado, Pablo; Lin, Zhaohui; Levinson, Ronnen; Millstein, Dev

    2015-12-15

    In this paper, we simulate temperature reductions during heat-wave events and during typical summer conditions from the installation of highly reflective "cool" roofs in the Chinese megacity of Guangzhou. We simulate temperature reductions during six of the strongest historical heat-wave events over the past decade, finding average urban midday temperature reductions of 1.2 °C. In comparison, we simulate 25 typical summer weeks between 2004 and 2008, finding average urban midday temperature reductions of 0.8 °C, indicating that air temperature sensitivity to urban albedo in Guangzhou varies with meteorological conditions. We find that roughly three-fourths of the variance in air temperature reductions across all episodes can be accounted for by a linear regression, including only three basic properties related to the meteorological conditions: mean daytime temperature, humidity, and ventilation to the greater Guangzhou urban area. While these results highlight the potential for cool roofs to mitigate peak temperatures during heat waves, the temperature reductions reported here are based on the upper bound case, which increases albedos of all roofs (but does not modify road albedo or wall albedo). PMID:26523605

  13. Strong negative effects of simulated heat waves in a tropical butterfly.

    PubMed

    Fischer, Klaus; Klockmann, Michael; Reim, Elisabeth

    2014-08-15

    Climate change poses a significant challenge to all natural systems on Earth. Especially increases in extreme weather events such as heat waves have the potential to strongly affect biodiversity, though their effects are poorly understood because of a lack of empirical data. Therefore, we here explore the sensitivity of a tropical ectotherm, which are in general believed to have a low warming tolerance, to experimentally simulated climate change using ecologically realistic diurnal temperature cycles. Increasing the mean temperature permanently by 3°C had mostly minor effects on developmental traits in the butterfly Bicyclus anynana. Simulated heat waves (strongly elevated temperatures for some time though retaining the same overall temperature mean), in contrast, caused strong negative effects by prolonging development time (by up to 10%) and reducing body mass (-21%), especially when combined with reduced relative humidity. Detrimental effects were carried over into the adult stage, diminishing subsequent performance. Most strikingly, higher temperatures suppressed adult immune function (haemocytes: -54%, lysozyme activity: -32%), which may potentially change the way species interact with antagonists. Heat waves thus reduced fitness parameters by 10-25% for development time and body mass and by up to 54% for immune parameters even in this plastic and widespread butterfly, exemplifying the potentially dramatic impact of extreme weather events on biodiversity. PMID:24902752

  14. Climate extremes and climate change: The Russian heat wave and other climate extremes of 2010

    NASA Astrophysics Data System (ADS)

    Trenberth, Kevin E.; Fasullo, John T.

    2012-09-01

    A global perspective is developed on a number of high impact climate extremes in 2010 through diagnostic studies of the anomalies, diabatic heating, and global energy and water cycles that demonstrate relationships among variables and across events. Natural variability, especially ENSO, and global warming from human influences together resulted in very high sea surface temperatures (SSTs) in several places that played a vital role in subsequent developments. Record high SSTs in the Northern Indian Ocean in May 2010, the Gulf of Mexico in August 2010, the Caribbean in September 2010, and north of Australia in December 2010 provided a source of unusually abundant atmospheric moisture for nearby monsoon rains and flooding in Pakistan, Colombia, and Queensland. The resulting anomalous diabatic heating in the northern Indian and tropical Atlantic Oceans altered the atmospheric circulation by forcing quasi-stationary Rossby waves and altering monsoons. The anomalous monsoonal circulations had direct links to higher latitudes: from Southeast Asia to southern Russia, and from Colombia to Brazil. Strong convection in the tropical Atlantic in northern summer 2010 was associated with a Rossby wave train that extended into Europe creating anomalous cyclonic conditions over the Mediterranean area while normal anticyclonic conditions shifted downstream where they likely interacted with an anomalously strong monsoon circulation, helping to support the persistent atmospheric anticyclonic regime over Russia. This set the stage for the "blocking" anticyclone and associated Russian heat wave and wild fires. Attribution is limited by shortcomings in models in replicating monsoons, teleconnections and blocking.

  15. Effect of heat waves on VOC emissions from vegetation and urban air quality

    NASA Astrophysics Data System (ADS)

    Churkina, G.; Kuik, F.; Lauer, A.; Bonn, B.; Butler, T. M.

    2015-12-01

    Programs to plant millions of trees in cities around the world aim at the reduction of summer temperatures, increase carbon storage, storm water control, provision of space for recreation, as well as poverty alleviation. Although these multiple benefits speak positively for urban greening programs, the programs do not take into account how close human and natural systems are coupled in urban areas. Elevated temperatures together with anthropogenic emissions of air and water pollutants distinguish the urban system. Urban and sub-urban vegetation responds to ambient changes and reacts with pollutants. Neglecting this coupling may lead to unforeseen drawbacks of urban greening programs. The potential for emissions of volatile organic compounds (VOC) from vegetation combined with anthropogenic emissions to produce ozone has long been recognized. This potential increases under rising temperatures. Here we investigate how heat waves affect emissions of VOC from urban vegetation and corresponding ground-level ozone. In this study we use Weather Research and Forecasting Model with coupled atmospheric chemistry (WRF-CHEM) to quantify these feedbacks in Berlin, Germany during the 2006 heat wave. VOC emissions from vegetation are simulated with MEGAN 2.0 coupled with WRF-CHEM. Our preliminary results indicate that contribution of VOCs from vegetation to ozone formation may increase by more than twofold during the heat wave period. We highlight the importance of the vegetation for urban areas under changing climate and discuss associated tradeoffs.

  16. Russia Browning: The 2010 Heat Wave Was Not an Isolated Event

    NASA Astrophysics Data System (ADS)

    Wright, C. K.; de Beurs, K. M.; Henebry, G. M.

    2011-12-01

    Record-high temperatures and wildfires eliminated nearly a third of Russia's 2010 wheat crop. Similar crop losses in Ukraine and Kazakhstan, combined with a Russian export ban, roiled international grain markets. Here we show that the 2010 crop failures were not isolated events, but rather the continuation of a decade-long browning trend across much of the Eurasian "breadbasket". Over the period 2001-2010, we find that nearly 40% of the Eurasian wheat belt (EWB) exhibited significant negative trends in the Normalized Difference Vegetation Index (NDVI). The height of the Russian heat wave was caused by severe atmospheric blocking during July and August of 2010. However, we find highly negative NDVI anomalies during the early growing season preceding the onset of atmospheric blocking; suggesting that land surface feedbacks linked to early season drying amplified the blocking event's severity and duration. The unusually warm and dry early growing season preceding the heat wave was consistent with the highly negative phase of the North Atlantic Oscillation (NAO) which emerged in 2009/2010. We also find an empirical link between the NAO's recent downward trend and browning of the EWB. Recent evidence that receding Arctic sea ice is forcing a downward trend in the NAO suggests the possibility that global climate change played a role in the Russian heat wave. Food security models predicting that the EWB will contribute an increasing share of global wheat production due to climate-change effects including longer growing seasons and warmer winters may be unrealistic given observed trends.

  17. THE SPATIAL AND TEMPORAL DEPENDENCE OF CORONAL HEATING BY ALFVEN WAVE TURBULENCE

    SciTech Connect

    Asgari-Targhi, M.; Van Ballegooijen, A. A.; Cranmer, S. R.; DeLuca, E. E.

    2013-08-20

    The solar atmosphere may be heated by Alfven waves that propagate up from the convection zone and dissipate their energy in the chromosphere and corona. To further test this theory, we consider wave heating in an active region observed on 2012 March 7. A potential field model of the region is constructed, and 22 field lines representing observed coronal loops are traced through the model. Using a three-dimensional (3D) reduced magnetohydrodynamics code, we simulate the dynamics of Alfven waves in and near the observed loops. The results for different loops are combined into a single formula describing the average heating rate Q as a function of position within the observed active region. We suggest this expression may be approximately valid also for other active regions, and therefore may be used to construct 3D, time-dependent models of the coronal plasma. Such models are needed to understand the role of thermal non-equilibrium in the structuring and dynamics of the Sun's corona.

  18. Stochastic heating and acceleration of minor ions by turbulent Alfven waves

    NASA Astrophysics Data System (ADS)

    Wang, C.; Wang, B.; Yoon, P. H.; Wu, C. S.

    2011-12-01

    The heating and acceleration of ions in the solar corona and the solar wind is a longstanding topic in solar-terrestrial physics. SOHO observations show that minor heavy ions have higher perpendicular temperature anisotropy and their outflow velocities are significantly higher than that of protons in the solar corona. It is also known that heavy ions, with mass-proportional temperatures, flow faster than the protons by approximately the local Alfven speed in the fast solar wind. The present work addresses the stochastic heating of minor ions by obliquely-propagating low-frequency Alfven waves. An important characteristic of the stochastic heating is unearthed by means of test particle simulation. That is, when the wave amplitude exceeds some threshold condition for stochasticity, the quasi-asymptotic kinetic temperature associated with the minor ions becomes independent of the wave amplitude and proportional to the ion mass, and it always approaches the value dictated by the Alfven speed, to wit, Tkin≈mivA2/2. During the course of the heating process the minor ions gain a net average parallel speed, v||˜vA in the laboratory frame. The physical mechanism for the asymptotically independent heating is the pickup process that involves the formation of spherical shell velocity distribution function via the pitch-angle scattering. These results are generally consistent with observational properties of minor ions. In the corona, minor ions may be not fully picked up and just a partial shell velocity distribution is formed. Thus, the minor ion temperature is highly anisotropic, and flow faster than protons by a fraction of the local Alfven speed. On the other hand, in the interplanetary space, the fully spherical shell velocity distribution may have been nearly formed, so the minor ion temperature is proportional to their mass, and flow faster than protons by about the local Alfven speed.

  19. Heating of coronal holes by the resonant absorption and dissipation of Alfven waves and its relation to solar wind acceleration

    NASA Technical Reports Server (NTRS)

    Ofman, L.; Davila, J. M.

    1995-01-01

    Coronal hole regions are well known sources of high-speed solar wind, however to account for the observed properties of the solar wind a source of momentum and heat must be included. Alfven waves were suggested as the possible source of heating that accelerates the solar wind. We investigate the propagation of the Alfven waves in coronal holes via numerical solution of the linearized 2-D resistive MHD equations in slab geometry. The Alfven waves are driven at the lower boundary of the coronal hole and propagate into the corona. The waves are reflected at the coronal hole boundary and part of the wave energy leaks out of the coronal hole. We compare the calculated wavelengths and the attenuation rate of the fast mode Alfven waves in the leaky waveguide formed by the coronal hole with the analytical ideal MHD solutions. The formation of resonance heating layers is found to occur when shear Alfven waves propagate in an inhomogeneous coronal hole. The heating is enhanced when fast mode waves couple to the shear Alfven waves. The narrow heating layers are formed near the location of the ideal resonance, which might occur near the coronal hole boundary for a nearly constant density coronal hole, surrounded by a higher density plasma. We investigate the dependence of the heating on the driver frequency, the Lundquist number, and on the heliocentric distance. and find that the low frequency Alfven waves can be an efficient source of heating at large distances from the Sun. We discuss the relation of our results to the observed properties of high-speed solar wind and coronal holes.

  20. 40 CFR 96.76 - Additional requirements to provide heat input data for allocations purposes.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... heat input data for allocations purposes. 96.76 Section 96.76 Protection of Environment ENVIRONMENTAL... to provide heat input data for allocations purposes. (a) The owner or operator of a unit that elects... also monitor and report heat input at the unit level using the procedures set forth in part 75 of...

  1. 40 CFR 96.76 - Additional requirements to provide heat input data for allocations purposes.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... heat input data for allocations purposes. 96.76 Section 96.76 Protection of Environment ENVIRONMENTAL... to provide heat input data for allocations purposes. (a) The owner or operator of a unit that elects... also monitor and report heat input at the unit level using the procedures set forth in part 75 of...

  2. 40 CFR 96.76 - Additional requirements to provide heat input data for allocations purposes.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... heat input data for allocations purposes. 96.76 Section 96.76 Protection of Environment ENVIRONMENTAL... to provide heat input data for allocations purposes. (a) The owner or operator of a unit that elects... also monitor and report heat input at the unit level using the procedures set forth in part 75 of...

  3. 40 CFR 96.76 - Additional requirements to provide heat input data for allocations purposes.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... heat input data for allocations purposes. 96.76 Section 96.76 Protection of Environment ENVIRONMENTAL... to provide heat input data for allocations purposes. (a) The owner or operator of a unit that elects... also monitor and report heat input at the unit level using the procedures set forth in part 75 of...

  4. 40 CFR 96.76 - Additional requirements to provide heat input data for allocations purposes.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... heat input data for allocations purposes. 96.76 Section 96.76 Protection of Environment ENVIRONMENTAL... to provide heat input data for allocations purposes. (a) The owner or operator of a unit that elects... also monitor and report heat input at the unit level using the procedures set forth in part 75 of...

  5. Geographical variation in relative risks associated with heat: Update of Spain's Heat Wave Prevention Plan.

    PubMed

    Díaz, J; Carmona, R; Mirón, I J; Ortiz, C; León, I; Linares, C

    2015-12-01

    A decade after the implementation of prevention plans designed to minimise the impact of high temperatures on health, some countries have decided to update these plans in order to improve the weakness detected in these ten years of operation. In the case of Spain, this update has fundamentally consisted of changing the so-called "threshold" or "trigger" temperatures used to activate the plan, by switching from temperature values based on climatological criteria to others obtained by epidemiological studies conducted on a provincial scale. This study reports the results of these "trigger" temperatures for each of Spain's 52 provincial capitals, as well as the impact of heat on mortality by reference to the relative risks (RRs) and attributable risks (ARs) calculated for natural as well as circulatory and respiratory causes. The results obtained for threshold temperatures and RRs show a more uniform behaviour pattern than those obtained using temperature values based on climatological criteria; plus a clear decrease in RRs of heat-associated mortality due to the three causes considered, at both a provincial and regional level as well as for Spain as a whole. The updating of prevention plans is regarded as crucial for optimising the operation of these plans in terms of reducing the effect of high temperatures on population health.

  6. Corrosion and Heat Transfer Characteristics of Water Dispersed with Carboxylate Additives and Multi Walled Carbon Nano Tubes

    NASA Astrophysics Data System (ADS)

    Moorthy, Chellapilla V. K. N. S. N.; Srinivas, Vadapalli

    2016-02-01

    This paper summarizes a recent work on anti-corrosive properties and enhanced heat transfer properties of carboxylated water based nanofluids. Water mixed with sebacic acid as carboxylate additive found to be resistant to corrosion and suitable for automotive environment. The carboxylated water is dispersed with very low mass concentration of carbon nano tubes at 0.025, 0.05 and 0.1 %. The stability of nanofluids in terms of zeta potential is found to be good with carboxylated water compared to normal water. The heat transfer performance of nanofluids is carried out on an air cooled heat exchanger similar to an automotive radiator with incoming air velocities across radiator at 5, 10 and 15 m/s. The flow Reynolds number of water is in the range of 2500-6000 indicating developing flow regime. The corrosion resistance of nanofluids is found to be good indicating its suitability to automotive environment. There is a slight increase in viscosity and marginal decrease in the specific heat of nanofluids with addition of carboxylate as well as CNTs. Significant improvement is observed in the thermal conductivity of nanofluids dispersed with CNTs. During heat transfer experimentation, the inside heat transfer coefficient and overall heat transfer coefficient has also improved markedly. It is also found that the velocity of air and flow rate of coolant plays an important role in enhancement of the heat transfer coefficient and overall heat transfer coefficient.

  7. Additive impacts on particle emissions from heating low emitting cooking oils

    NASA Astrophysics Data System (ADS)

    Amouei Torkmahalleh, M.; Zhao, Y.; Hopke, P. K.; Rossner, A.; Ferro, A. R.

    2013-08-01

    The effect of five additives, including table salt, sea salt, black pepper, garlic powder, and turmeric, on the emission of PM2.5 and ultrafine particles (UFP) from heated cooking oil (200 °C) were studied. One hundred milligrams of the additives were added individually to either canola or soybean oil without stirring. Black pepper, table salt, and sea salt reduced the PM2.5 emission of canola oil by 86% (p < 0.001), 88% (p < 0.001), and 91% (p < 0.001), respectively. Black pepper, table salt, and sea salt also decreased the total particle number emissions of canola oil by 45% (p = 0.003), 52% (p = 0.001), and 53% (p < 0.001), respectively. Turmeric and garlic powder showed no changes in the PM2.5 and total number emissions of canola oil. Table salt and sea salt, decreased the level of PM2.5 emissions from soybean oil by 47% (p < 0.001) and 77% (p < 0.001), respectively. No differences in the PM2.5 emissions were observed when other additives were added to soybean oil. Black pepper, sea salt, and table salt reduced the total particle number emissions from the soybean oil by 51%, 61% and 68% (p < 0.001), respectively. Turmeric and garlic powder had no effect on soybean oil with respect to total particle number emissions. Our results indicate that table salt, sea salt, and black pepper can be used to reduce the particle total number and PM2.5 emissions when cooking with oil.

  8. Heat Waves

    MedlinePlus

    ... by the Cass (ND) and Clay (MN) Emergency Planning Partnerships. Created with funding provided by Fargo Cass Public Health through the Cities Readiness Initiative (CRI) Adapted by Healthy Roads Media ( ...

  9. Heat wave event dynamics over the territory of Ukraine in the context of the global climate change

    NASA Astrophysics Data System (ADS)

    Khomenko, Inna; Dereviaha, Oleksandr

    2016-04-01

    General circulation models of climate change predict that heatwaves will become more frequent and intense, especially in the higher latitudes, affecting large metropolitan areas. In the study for nine cities of the Ukraine (Kyiv, Lviv, Odesa, Poltava, Simferopol, Uzhgorod, Uman, Kharkiv, Chernivtsi), the series of average daily maximum temperature for periods of 41 to 112 years are analyzed during the warm season (May, 1 to September, 30). The study is based on the Peaks over Threshold Approach, applied to study the frequency of heat waves using three heat indices such as 90th percentile (TX90p), 95th percentile (TX95) and heat wave criterion proposed by WMO (TXA5). For five stations of Chernivtsi, Kharkiv, Kyiv, Odesa and Poltava a linear trend shows the decrease in maximum temperature. For the rest of the stations there is the increase in the year highest temperature. For all stations stepped trend is characterized strong change in the mean value of block maximum temperature. In Kyiv and Lviv the stepped and linear trends don't agree. It shows that in these stations there is different type of variability (for example, cyclical fluctuations). In comparison with the 1961-1990 period for all stations in question number of heat waves is growing. However, most increment of number of heat wave days in the period of 2001-2010 are observed in Kyiv, Simferopol and Uman. For these stations rapid growth in days with maximum temperatures being more than 30 and 35°C, are obtained as well. In Lviv, Poltava and Kharkiv uneven decrease in number of heat wave days occur during XX century for all indices in question. In the other stations periods with small number of heat wave days alternates with ones with large number of heat wave days, which correspond to periods of decrease and increase of maximum temperature. The least length of heat waves takes place in Lviv (doesn't exceed 10 days), Odesa and Chernivtsi (doesn't exceed 15 days) for all indices. The largest length of heat

  10. The impact of temperature on mortality in a subtropical city: effects of cold, heat, and heat waves in São Paulo, Brazil.

    PubMed

    Son, Ji-Young; Gouveia, Nelson; Bravo, Mercedes A; de Freitas, Clarice Umbelino; Bell, Michelle L

    2016-01-01

    Understanding how weather impacts health is critical, especially under a changing climate; however, relatively few studies have investigated subtropical regions. We examined how mortality in São Paulo, Brazil, is affected by cold, heat, and heat waves over 14.5 years (1996-2010). We used over-dispersed generalized linear modeling to estimate heat- and cold-related mortality, and Bayesian hierarchical modeling to estimate overall effects and modification by heat wave characteristics (intensity, duration, and timing in season). Stratified analyses were performed by cause of death and individual characteristics (sex, age, education, marital status, and place of death). Cold effects on mortality appeared higher than heat effects in this subtropical city with moderate climatic conditions. Heat was associated with respiratory mortality and cold with cardiovascular mortality. Risk of total mortality was 6.1% (95% confidence interval 4.7, 7.6%) higher at the 99th percentile of temperature than the 90th percentile (heat effect) and 8.6% (6.2, 11.1%) higher at the 1st compared to the 10th percentile (cold effect). Risks were higher for females and those with no education for heat effect, and males for cold effect. Older persons, widows, and non-hospital deaths had higher mortality risks for heat and cold. Mortality during heat waves was higher than on non-heat wave days for total, cardiovascular, and respiratory mortality. Our findings indicate that mortality in São Paulo is associated with both cold and heat and that some subpopulations are more vulnerable. PMID:25972308

  11. The impact of temperature on mortality in a subtropical city: effects of cold, heat, and heat waves in São Paulo, Brazil

    NASA Astrophysics Data System (ADS)

    Son, Ji-Young; Gouveia, Nelson; Bravo, Mercedes A.; de Freitas, Clarice Umbelino; Bell, Michelle L.

    2016-01-01

    Understanding how weather impacts health is critical, especially under a changing climate; however, relatively few studies have investigated subtropical regions. We examined how mortality in São Paulo, Brazil, is affected by cold, heat, and heat waves over 14.5 years (1996-2010). We used over-dispersed generalized linear modeling to estimate heat- and cold-related mortality, and Bayesian hierarchical modeling to estimate overall effects and modification by heat wave characteristics (intensity, duration, and timing in season). Stratified analyses were performed by cause of death and individual characteristics (sex, age, education, marital status, and place of death). Cold effects on mortality appeared higher than heat effects in this subtropical city with moderate climatic conditions. Heat was associated with respiratory mortality and cold with cardiovascular mortality. Risk of total mortality was 6.1 % (95 % confidence interval 4.7, 7.6 %) higher at the 99th percentile of temperature than the 90th percentile (heat effect) and 8.6 % (6.2, 11.1 %) higher at the 1st compared to the 10th percentile (cold effect). Risks were higher for females and those with no education for heat effect, and males for cold effect. Older persons, widows, and non-hospital deaths had higher mortality risks for heat and cold. Mortality during heat waves was higher than on non-heat wave days for total, cardiovascular, and respiratory mortality. Our findings indicate that mortality in São Paulo is associated with both cold and heat and that some subpopulations are more vulnerable.

  12. Do asteroids evaporate near pulsars? Induction heating by pulsar waves revisited

    NASA Astrophysics Data System (ADS)

    Kotera, Kumiko; Mottez, Fabrice; Voisin, Guillaume; Heyvaerts, Jean

    2016-07-01

    Aims: We investigate the evaporation of close-by pulsar companions, such as planets, asteroids, and white dwarfs, by induction heating. Methods: Assuming that the outflow energy is dominated by a Poynting flux (or pulsar wave) at the location of the companions, we calculate their evaporation timescales, by applying the Mie theory. Results: Depending on the size of the companion compared to the incident electromagnetic wavelength, the heating regime varies and can lead to a total evaporation of the companion. In particular, we find that inductive heating is mostly inefficient for small pulsar companions, although it is generally considered the dominant process. Conclusions: Small objects like asteroids can survive induction heating for 104 yr at distances as small as 1 R⊙ from the neutron star. For degenerate companions, induction heating cannot lead to evaporation and another source of heating (likely by kinetic energy of the pulsar wind) has to be considered. It was recently proposed that bodies orbiting pulsars are the cause of fast radio bursts; the present results explain how those bodies can survive in the pulsar's highly energetic environment.

  13. Comparative Calculation of Heat Exchange with the Ground in Residential Building Including Periodes of Heat Waves

    NASA Astrophysics Data System (ADS)

    Staszczuk, Anna; Kuczyński, Tadeusz; Wojciech, Magdalena; Ziembicki, Piotr

    2016-06-01

    The paper provides verification of 3D transient ground-coupled model to calculation of heat exchange between ground and typical one-storey, passive residential building. The model was performed with computer software WUFI®plus and carried out to estimate the indoor air temperatures during extending hot weather periods. For verifying the results of calculations performed by the WUFI®plus software, the most recent version of EnergyPlus software version was used. Comparison analysis of calculation results obtained with the two above mentioned calculation method was made for two scenarios of slab on ground constructions: without thermal insulation and with thermal insulation under the whole slab area. Comprehensive statistical analysis was done including time series analysis and descriptive statistics parameters.

  14. Inertia gravity waves in a rotating, differentially heated annulus with an upper free surface

    NASA Astrophysics Data System (ADS)

    Randriamampianina, Anthony; Harlander, Uwe; Vincze, Miklos; von Larcher, Thomas; Viazzo, Stephane

    2015-04-01

    Inertia gravity waves (IGWs) are ubiquitous in the atmosphere and oceans, and are known to play a fundamental role in a wide variety of processes, among others the induction and modulation of turbulence. Observations and simulations have revealed their spontaneous occurrence simultaneously with the onset of baroclinic instability, recognized to be one of the dominant energetic processes in the large-scale atmospheric and oceanic circulations. In spite of intensive research activities these last decades, the generation mechanism and the propagation of IGWs, as well as their interaction with large-scale structures triggering locally chaotic motions, remain poorly understood. A better understanding of these phenomena is therefore mandatory for the development of IGW's parameterization schemes actually required for numerical global weather prediction. A combined laboratory experiment and direct numerical simulations study is proposed for the detailed investigations of instabilities arising within a differentially heated rotating annulus, the baroclinic cavity. The configuration corresponds to an experimental setup used at BTU, Cottbus Senftenberg, Germany [1], characterized by an open upper surface and filled with water (Pr = 7). Infrared thermography and simultaneous kalliroscope visualization in horizontal planes, illuminated by a laser sheet, have been applied to detect the surface signatures of IGWs. These findings confirmed the computations carried out by three different numerical approaches, using either spectral methods, high order compact finite difference scheme (M2P2, Marseille), or the EULAG code (Freie Universitaet Berlin). These small-scale features have been observed in addition to those developing along the inner cold cylinder, previously identified by simulations in a closed cavity, filled with a liquid defined by Pr = 16 [2]. These new IGWs show characteristics similar to the ones obtained by [3] at the exit of the meandering jet between the cyclonic

  15. Heat wave beats green wave: the effect of a climate extreme on alpine grassland phenology as seen by phenocams

    NASA Astrophysics Data System (ADS)

    Cremonese, Edoardo; Filippa, Gianluca; Migliavacca, Mirco; Siniscalco, Consolata; Oddi, Ludovica; Galvagno, Marta

    2016-04-01

    The year 2015 has been one of the warmest on record for many regions of the world. The record-breaking temperatures did not spare the European Alps, where the summer anomaly reached +4°C. This heat wave caused important impacts on the seasonal development and structural properties of alpine grasslands that deserve investigations. Phenocams are useful tools to describe canopy greenness seasonal dynamics and many recent studies demonstrated that the major phenological events (e.g. budbrust, senescence, …) can be extracted from greenness trajectories. In contrast, little is know about their capabilities to describe the impact of extreme climate events on a fully developed canopy. Moreover the relation between quantitative structural and functional vegetation properties (e.g. biomass, LAI, …) and phenocam data remains poorly investigated. In this study we examine the impact of the 2015 summer heat wave on a subalpine grassland by jointly analyzing phenocam greenness trajectories, proximal sensing and flux data together with field measures of vegetation structural properties. The effect of different environmental drivers on greenness seasonal development was further evaluated by a modeling approach (GSI model). Phenocam tracked the impact of heatwave 2015 that caused a lower canopy development and an anticipation of yellowing by more than 2 months. The same pattern was observed for CO2 fluxes, NDVI and field measures. GSI model results show that during the heatwave, a combination of moisture and high temperature limitation was responsible for the observed reduction of the canopy development. Moreover, spatially explicit analysis of digital images allowed to highlight the differential response of specific plant functional types to the extreme event.

  16. Assessing projected changes in heat waves over Northern Europe using two regional climate models at 8-km resolution.

    NASA Astrophysics Data System (ADS)

    Fox Maule, Cathrine; Christensen, Ole B.; Mayer, Stephanie; Thejll, Peter

    2013-04-01

    As temperatures in Northern Europe increase due to climate change the occurrence of extreme events such as heat waves is likely to change. A higher occurrence rate of heat waves can have serious health consequences, in particular for the elderly, but also for very young children and the infirm. Not only the occurrence rate of heat waves, but also changes in the duration of individual heat waves, is of importance. It is therefore of relevance to investigate how the occurrence of heat waves is likely to increase in the future, to allow for adaptation. We have looked at the projected changes in the occurrence rate of heat waves in a part of northern Europe including southern Scandinavia, the Baltic Sea and the North Sea, according to two different greenhouse gas emission scenarios: RCP4.5 and RCP8.5. In this study we have chosen to use the Danish Meteorological Institutes definition, in which a high temperature event is classified as a heat wave if the average of the maximum temperature of a period of at least 3 consecutive days exceeds 28°C. To estimate the change in the occurrence rate of heat waves we have used two different GCM-RCM combinations, NorESM-WRF (BCCR) and EC-EARTH-HIRHAM5 (DMI). Both regional models have down-scaled the global models to a resolution of about 8 km, and hourly values of several parameters including temperature, precipitation and wind have been stored. We compare the climate model data from three different time slices, 1981-2010 run with historical greenhouse gas concentrations, 2021-2050 (RPC4.5 and RCP 8.5) and 2071-2100 (RPC4.5 and RCP 8.5), to see the time evolution in the occurrence rate of heat waves for the two RCP scenarios. Our results indicate that the occurrence rate of heat waves in this region will increase as a consequence of global warming, and that individual heat waves will tend to last longer.

  17. Coronal Heating via Alfvén Wave coupling with MHD Turbulence

    NASA Astrophysics Data System (ADS)

    Oughton, S.; Matthaeus, W. H.; Zank, G. P.

    1999-10-01

    Current evidence suggests that physically acceptable models for the origin of the high-latitude solar wind will involve some process(es) which deposits significant heat within a few solar radii of the photosphere [1]. Moreover, the process is likely to rely heavily on the coronal magnetic field [2]. Here we present a candidate mechanism for heating of open field line regions of the corona. The mechanism involves the coupling of LOW frequency Alfven waves generated in the chromosphere, their (partial) reflection off density and field gradients, and MHD turbulence which is quasi-two dimensional (relative to the mean magnetic field). The essentially non-propagating nature of the latter means that energy deposited in these fluctuations by the driving waves can undergo a turbulent cascade to small transverse scales (via, for example, reconnection) at approximately the same height at which the coupling occurs: the fast Alfven wave propagation timescale is not relevant to the quasi-2D dynamics and the speed of the nascent wind is low in this region. Once the energy reaches sufficiently small perpendicular length scales, dissipative processes convert it into heat at a rate expected to be insensitive to the mean field strength. We will present and discuss a phenomenology for the process along with ``proof of principle'' support from reduced MHD simulations. Estimates of achievable heating efficiencies based on both the turbulence modeling and the simulations are consistent and encourage further investigation of the model's quantitative feasibility. Supported by NASA grant NAG5-7164. [1] Habbal, S.R., R. Esser, M. Guhathakurta, and R.R. Fisher, Geophys. Res. Lett., 22, 1465, 1995 [2] McKenzie, J.F., M. Banaszkiewicz, and W.I. Axford, Astron. Astrophys. 303, L45, 1995.

  18. Relating Alfvén Wave Heating Model to Observations of a Solar Active Region

    NASA Astrophysics Data System (ADS)

    Yoritomo, J. Y.; Van Ballegooijen, A. A.

    2012-12-01

    We compared images from the Solar Dynamics Observatory's (SDO) Atmospheric Imaging Assembly (AIA) with simulations of propagating and dissipating Alfvén waves from a three-dimensional magnetohydrodynamic (MHD) model (van Ballegooijen et. al 2011; Asgari-Targhi & van Ballegooijen 2012). The goal was to search for observational evidence of Alfvén waves in the solar corona and understand their role in coronal heating. We looked at one particular active region on the 5th of May 2012. Certain distinct loops in the SDO/AIA observations were selected and expanded. Movies were created from these selections in an attempt to discover transverse motions that may be Alfvén waves. Using a magnetogram of that day and the corresponding synoptic map, a potential field model was created for the active region. Three-dimensional MHD models for several loops in different locations in the active region were created. Each model specifies the temperature, pressure, magnetic field strength, average heating rate, and other parameters along the loop. We find that the heating is intermittent in the loops and reflection occurs at the transition region. For loops at larger and larger height, a point is reached where thermal non-equilibrium occurs. In the center this critical height is much higher than in the periphery of the active region. Lastly, we find that the average heating rate and coronal pressure decrease with increasing height in the corona. This research was supported by an NSF grant for the Smithsonian Astrophysical Observatory (SAO) Solar REU program and a SDO/AIA grant for the Smithsonian Astrophysical Observatory.

  19. Resonance scattering and radiation force calculations for an elastic cylinder using the translational addition theorem for cylindrical wave functions

    SciTech Connect

    Mitri, F. G.

    2015-09-15

    The standard Resonance Scattering Theory (RST) of plane waves is extended for the case of any two-dimensional (2D) arbitrarily-shaped monochromatic beam incident upon an elastic cylinder with arbitrary location using an exact methodology based on Graf’s translational addition theorem for the cylindrical wave functions. The analysis is exact as it does not require numerical integration procedures. The formulation is valid for any cylinder of finite size and material that is immersed in a nonviscous fluid. Partial-wave series expansions (PWSEs) for the incident, internal and scattered linear pressure fields are derived, and the analysis is further extended to obtain generalized expressions for the on-axis and off-axis acoustic radiation force components. The wave-fields are expressed using generalized PWSEs involving the beam-shape coefficients (BSCs) and the scattering coefficients of the cylinder. The off-axial BSCs are expressed analytically in terms of an infinite PWSE with emphasis on the translational offset distance d. Numerical computations are considered for a zeroth-order quasi-Gaussian beam chosen as an example to illustrate the analysis. Acoustic resonance scattering directivity diagrams are calculated by subtracting an appropriate background from the expression of the scattered pressure field. In addition, computations for the radiation force exerted on an elastic cylinder centered on the axis of wave propagation of the beam, and shifted off-axially are analyzed and discussed.

  20. Resonance scattering and radiation force calculations for an elastic cylinder using the translational addition theorem for cylindrical wave functions

    NASA Astrophysics Data System (ADS)

    Mitri, F. G.

    2015-09-01

    The standard Resonance Scattering Theory (RST) of plane waves is extended for the case of any two-dimensional (2D) arbitrarily-shaped monochromatic beam incident upon an elastic cylinder with arbitrary location using an exact methodology based on Graf's translational addition theorem for the cylindrical wave functions. The analysis is exact as it does not require numerical integration procedures. The formulation is valid for any cylinder of finite size and material that is immersed in a nonviscous fluid. Partial-wave series expansions (PWSEs) for the incident, internal and scattered linear pressure fields are derived, and the analysis is further extended to obtain generalized expressions for the on-axis and off-axis acoustic radiation force components. The wave-fields are expressed using generalized PWSEs involving the beam-shape coefficients (BSCs) and the scattering coefficients of the cylinder. The off-axial BSCs are expressed analytically in terms of an infinite PWSE with emphasis on the translational offset distance d. Numerical computations are considered for a zeroth-order quasi-Gaussian beam chosen as an example to illustrate the analysis. Acoustic resonance scattering directivity diagrams are calculated by subtracting an appropriate background from the expression of the scattered pressure field. In addition, computations for the radiation force exerted on an elastic cylinder centered on the axis of wave propagation of the beam, and shifted off-axially are analyzed and discussed.

  1. Minor ion heating in spectra of linearly and circularly polarized Alfvén waves: Thermal and non-thermal motions associated with perpendicular heating

    SciTech Connect

    Dong, Chuanfei

    2014-02-15

    Minor ion (such as He{sup 2+}) heating via nonresonant interaction with spectra of linearly and circularly polarized Alfvén waves (LPAWs and CPAWs hereafter) is studied. The obtained analytic solutions are in good agreement with the simulation results, indicating that newborn ions are heated by low-frequency Alfvén waves with finite amplitude in low-beta plasmas such as the solar corona. The analytic solutions also reproduce the preferential heating of heavy ions in the solar wind. In the presence of parallel propagating Alfvén waves, turbulence-induced particle motion is clearly observed in the wave (magnetic field) polarized directions. After the waves diminish, the newborn ions are heated, which is caused by the phase difference (randomization) between ions due to their different parallel thermal motions. The heating is dominant in the direction perpendicular to the ambient magnetic field. The perpendicular heating, η=(T{sub i⊥}{sup R}−T{sub i0⊥}{sup R})/T{sub i0⊥}{sup R} (where T{sub i0⊥}{sup R} and T{sub i⊥}{sup R} are the perpendicular temperature of species i before and after genuine heating, respectively), in the spectrum of CPAWs is a factor of two stronger than that of LPAWs. Moreover, we also study the effect of field-aligned differential flow speed of species i relative to H{sup +}, δv{sub ip}=(v{sub i}−v{sub p})·B/|B| (where v{sub i} and v{sub p} denote vector velocities of the H{sup +} and species i, respectively), on the perpendicular heating. It reveals that large drift speed, v{sub d}=δv{sub ip}, has an effect on reducing the efficiency of perpendicular heating, which is consistent with observations.

  2. Record-breaking 2015 heat waves in Central Europe: how to view them in the climate change context?

    NASA Astrophysics Data System (ADS)

    Lhotka, Ondrej; Plavcová, Eva; Kyselý, Jan

    2016-04-01

    The 2015 summer was the warmest summer ever observed in Central Europe according to many characteristics, including the overall severity of heat waves. We assess how unusual this summer was by i) comparing the seasonal temperature anomalies and severity of heat waves against long-term temperature records at Central European stations, ii) evaluating its temperature characteristics at the continental scale against hot summers and major heat waves affecting Europe recently (including the 2003 western-European heat waves and the 2010 Russian heat waves), and iii) identifying time slices in climate change scenarios for the 21st century in which similar events are projected to occur over Central Europe at least once per decade. In the last point, we make use of a large ensemble of RCM simulations from CORDEX and ENSEMBLES projects and critically evaluate their ability to simulate events such as the 2015 summer (in terms of both seasonal temperature anomalies and heat waves, including their spatial extent). We examine also how results for the climate change scenarios depend on radiative forcing and driving global models.

  3. High Density Plasma Heating by EC-Waves Injected from the High-Field Side for Mode Conversion to Electron Bernstein Waves in LHD

    NASA Astrophysics Data System (ADS)

    Yoshimura, Y.; Kubo, S.; Shimozuma, T.; Igami, H.; Takahashi, H.; Nishiura, M.; Ogasawara, S.; Makino, R.; Mutoh, T.; Yamada, H.; Komori, A.

    2013-02-01

    To realize an excitation of electron Bernstein waves (EBW) via mode conversion from X-mode waves injected from the high magnetic field side (HFS), new inner-vessel mirrors were installed close to a helical coil in the large helical device (LHD). 77 GHz electron cyclotron (EC) wave beams injected from an existing EC-wave injection system toward the new mirror are reflected on the mirror so that the beams are injected to plasmas from HFS. Evident increases in the electron temperature at the plasma core region and the plasma stored energy were observed by the HFS beam injection to the plasmas with the line-average electron density of 7.5×1019 m-3, which is slightly higher than the plasma cut-off density of 77 GHz EC-waves, 7.35×1019 m-3. The heating efficiency evaluated from the changes in the time derivative of the plasma stored energy reached ~70%. Although so far it is not clear which is the main cause of the heating effect, the mode-converted EBW or the X-mode wave itself injected from the HFS, an effective heating of high-density plasma over the plasma cut-off of EC-wave was successfully demonstrated.

  4. Climate extremes in urban area and their impact on human health: the summer heat waves

    NASA Astrophysics Data System (ADS)

    Baldi, Marina

    2014-05-01

    In the period 1951-2012 the average global land and ocean temperature has increased by approximately 0.72°C [0.49-0.89] when described by a linear trend, and is projected to rapidly increase. Each of the past three decades has been warmer than all the previous decades, with the decade of the 2000's as the warmest, and, since 1880, nine of the ten warmest years are in the 21st century, the only exception being 1998, which was warmed by the strongest El Niño event of the past century. In parallel an increase in the frequency and intensity of extremely hot days is detected with differences at different scales, which represent an health risk specially in largely populated areas as documented for several regions in the world including the Euro-Mediterranean region. If it is still under discussion if heat wave episodes are a direct result of the warming of the lower troposphere, or if, more likely, they are a regional climate event, however heat episodes have been studied in order to define their correlation with large scale atmospheric patterns and with changes in the regional circulation. Whatever the causes and the spatio-temporal extension of the episodes, epidemiological studies show that these conditions pose increasing health risks inducing heat-related diseases including hyperthermia and heat stress, cardiovascular and respiratory illnesses in susceptible individuals with a significant increase in morbidity and mortality especially in densely populated urban areas. In several Mediterranean cities peaks of mortality associated with extremely high temperature (with simultaneous high humidity levels) have been documented showing that, in some cases, a large increase in daily mortality has been reached compared to the average for the period. The number of fatalities during the summer 2003 heat wave in Europe was estimated to largely exceed the average value of some between 22000 and 50000 cases. In the same summer it was also unusually hot across much of Asia, and

  5. Al 1s-2p Absorption Spectroscopy of Shock-Wave Heating and Compression in Laser-Driven Planar Foil

    SciTech Connect

    Sawada, H.; Regan, S.P.; Radha, P.B.; Epstein, R.; Li, D.; Goncharov, V.N.; Hu, S.X.; Meyerhofer, D.D.; Delettrez, J.A.; Jaanimagi, P.A.; Smalyuk, V.A.; Boehly, T.R.; Sangster, T.C.; Yaakobi, B.; Mancini, R.C.

    2009-05-19

    Time-resolved Al 1s-2p absorption spectroscopy is used to diagnose direct-drive, shock-wave heating and compression of planar targets having nearly Fermi-degenerate plasma conditions (Te ~ 10–40 eV, rho ~ 3–11 g/cm^3) on the OMEGA Laser System [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)]. A planar plastic foil with a buried Al tracer layer was irradiated with peak intensities of 10^14–10^15 W/cm^2 and probed with the pseudocontinuum M-band emission from a point-source Sm backlighter in the range of 1.4–1.7 keV. The laser ablation process launches 10–70 Mbar shock waves into the CH/Al/CH target. The Al 1s-2p absorption spectra were analyzed using the atomic physic code PRISMSPECT to infer Te and rho in the Al layer, assuming uniform plasma conditions during shock-wave heating, and to determine when the heat front penetrated the Al layer. The drive foils were simulated with the one-dimensional hydrodynamics code LILAC using a flux-limited (f =0.06 and f =0.1) and nonlocal thermal-transport model [V. N. Goncharov et al., Phys. Plasmas 13, 012702 (2006)]. The predictions of simulated shock-wave heating and the timing of heat-front penetration are compared to the observations. The experimental results for a wide variety of laser-drive conditions and buried depths have shown that the LILAC predictions using f = 0.06 and the nonlocal model accurately model the shock-wave heating and timing of the heat-front penetration while the shock is transiting the target. The observed discrepancy between the measured and simulated shock-wave heating at late times of the drive can be explained by the reduced radiative heating due to lateral heat flow in the corona.

  6. A survey of electron Bernstein wave heating and current drive potential for spherical tokamaks

    NASA Astrophysics Data System (ADS)

    Urban, Jakub; Decker, Joan; Peysson, Yves; Preinhaelter, Josef; Shevchenko, Vladimir; Taylor, Gary; Vahala, Linda; Vahala, George

    2011-08-01

    The electron Bernstein wave (EBW) is typically the only wave in the electron cyclotron (EC) range that can be applied in spherical tokamaks for heating and current drive (H&CD). Spherical tokamaks (STs) operate generally in high-β regimes, in which the usual EC O- and X-modes are cut off. In this case, EBWs seem to be the only option that can provide features similar to the EC waves—controllable localized H&CD that can be used for core plasma heating as well as for accurate plasma stabilization. The EBW is a quasi-electrostatic wave that can be excited by mode conversion from a suitably launched O- or X-mode; its propagation further inside the plasma is strongly influenced by the plasma parameters. These rather awkward properties make its application somewhat more difficult. In this paper we perform an extensive numerical study of EBW H&CD performance in four typical ST plasmas (NSTX L- and H-mode, MAST Upgrade, NHTX). Coupled ray-tracing (AMR) and Fokker-Planck (LUKE) codes are employed to simulate EBWs of varying frequencies and launch conditions, which are the fundamental EBW parameters that can be chosen and controlled. Our results indicate that an efficient and universal EBW H&CD system is indeed viable. In particular, power can be deposited and current reasonably efficiently driven across the whole plasma radius. Such a system could be controlled by a suitably chosen launching antenna vertical position and would also be sufficiently robust.

  7. Surveillance of Summer Mortality and Preparedness to Reduce the Health Impact of Heat Waves in Italy

    PubMed Central

    Michelozzi, Paola; de’ Donato, Francesca K.; Bargagli, Anna Maria; D’Ippoliti, Daniela; De Sario, Manuela; Marino, Claudia; Schifano, Patrizia; Cappai, Giovanna; Leone, Michela; Kirchmayer, Ursula; Ventura, Martina; di Gennaro, Marta; Leonardi, Marco; Oleari, Fabrizio; De Martino, Annamaria; Perucci, Carlo A.

    2010-01-01

    Since 2004, the Italian Department for Civil Protection and the Ministry of Health have implemented a national program for the prevention of heat-health effects during summer, which to-date includes 34 major cities and 93% of the residents aged 65 years and over. The Italian program represents an important example of an integrated approach to prevent the impact of heat on health, comprising Heat Health Watch Warning Systems, a mortality surveillance system and prevention activities targeted to susceptible subgroups. City-specific warning systems are based on the relationship between temperature and mortality and serve as basis for the modulation of prevention measures. Local prevention activities, based on the guidelines defined by the Ministry of Health, are constructed around the infrastructures and services available. A key component of the prevention program is the identification of susceptible individuals and the active surveillance by General Practitioners, medical personnel and social workers. The mortality surveillance system enables the timely estimation of the impact of heat, and heat waves, on mortality during summer as well as to the evaluation of warning systems and prevention programs. Considering future predictions of climate change, the implementation of effective prevention programs, targeted to high risk subjects, become a priority in the public health agenda. PMID:20623023

  8. Wave Heating in Ion Cyclotron Ranges of Frequencies in RT-1

    NASA Astrophysics Data System (ADS)

    Nishiura, M.; Yoshida, Z.; Yano, Y.; Kawazura, Y.; Mushiake, T.; Saitoh, H.; Yamasaki, M.; Kashyap, A.; Takahashi, N.; Nakatsuka, M.; Fukuyama, A.

    2015-11-01

    The magnetosphere plasma device RT-1 has been developed for the studies on magnetosphere and advanced fusion plasmas. A levitated superconducting coil produces magnetic dipole fields that realize a high confinement state. The electron cyclotron resonance heating (ECRH) with 8.2 GHz and 50 kW produces the plasmas with hot electrons in a few ten keV range. We reported that the local electron beta exceeded 1 in RT-1 plasmas. In such situation, the ions still remain cold at a few ten eV. Heating ions is expected to access high ion beta state and to improve the plasma confinement theoretically. Therefore the ion cyclotron range of frequencies (ICRF) heating with 2-4 MHz and 10 kW is being prepared in RT-1. Based on the results of the TASK-WF2 code, the ∩ shape loop antenna was designed for a slow wave excitation, and was implemented in the RT-1. In the ICRF heating experiments, a base plasma was sustained by ECRH. We observed the clear increase in diamagnetic signals and impurity ion temperature (CIII) in helium plasmas at the neutral gas pressure of 3 mPa, if the ICRF power of 10 kW is comparable to the ECRH one. This result is the first time in a magnetosphere plasma device. The results related to the ICRF heating will be presented in detail. JSPS KAKENHI Grant Nos 23224014 and 24360384.

  9. Educing the emission mechanism of internal gravity waves in the differentially heat rotating annulus

    NASA Astrophysics Data System (ADS)

    Rolland, Joran; Hien, Steffen; Achatz, Ulrich; Borchert, Sebastian; Fruman, Mark

    2016-04-01

    Understanding the lifecycle of gravity waves is fundamental to a good comprehension of the dynamics of the atmosphere. In this lifecycle, the emission mechanisms may be the most elusive. Indeed, while the emission of gravity waves by orography or convection is well understood, the so-called spontaneous emission is still a quite open topic of investigation [1]. This type of emission usually occur very near jet-front systems in the troposphere. In this abstract, we announce our numerical study of the question. Model systems of the atmosphere which can be easily simulated or built in a laboratory have always been an important part of the study of atmospheric dynamics, alongside global simulations, in situ measurements and theory. In the case of the study of the spontaneous emission of gravity waves near jet-front systems, the differentially heated rotating annulus set up has been proposed and extensively used. It comprises of an annular tank containing water: the inner cylinder is kept at a cold temperature while the outer cylinder is kept at a warm temperature. The whole system is rotating. Provided the values of the control parameters (temperature, rotation rate, gap between the cylinders, height of water) are well chosen, the resulting flow mimics the troposphere at midlatitudes: it has a jet stream, and a baroclinic lifecycle develops on top of it. A very reasonable ratio of Brunt-Väisälä frequency over rotation rate of the system can be obtained, so as to be as close to the atmosphere as possible. Recent experiments as well as earlier numerical simulations in our research group have shown that gravity waves are indeed emitted in this set up, in particular near the jet front system of the baroclinic wave [2]. After a first experimental stage of characterising the emitted wavepacket, we focused our work on testing hypotheses on the gravity wave emission mechanism: we have tested and validated the hypothesis of spontaneous imbalance generated by the flow in

  10. Reconciling two approaches to attribution of the 2010 Russian heat wave

    NASA Astrophysics Data System (ADS)

    Otto, F. E. L.; Massey, N.; van Oldenborgh, G. J.; Jones, R. G.; Allen, M. R.

    2012-02-01

    In the summer 2010 Western Russia was hit by an extraordinary heat wave, with the region experiencing by far the warmest July since records began. Whether and to what extent this event is attributable to anthropogenic climate change is controversial. Dole et al. (2011) report the 2010 Russian heat wave was “mainly natural in origin” whereas Rahmstorf and Coumou (2011) write that with a probability of 80% “the 2010 July heat record would not have occurred” without the large-scale climate warming since 1980, most of which has been attributed to the anthropogenic increase in greenhouse gas concentrations. The latter explicitly state that their results “contradict those of Dole et al. (2011).” Here we use the results from a large ensemble simulation experiment with an atmospheric general circulation model to show that there is no substantive contradiction between these two papers, in that the same event can be both mostly internally-generated in terms of magnitude and mostly externally-driven in terms of occurrence-probability. The difference in conclusion between these two papers illustrates the importance of specifying precisely what question is being asked in addressing the issue of attribution of individual weather events to external drivers of climate.

  11. Drought and Heat Waves: The Role of SST and Land Surface Feedbacks

    NASA Technical Reports Server (NTRS)

    Schubert, Siegfried

    2011-01-01

    Drought occurs on a wide range of time scales, and within a variety of different types of regional climates. At the shortest time scales it is often associated with heat waves that last only several weeks to a few months but nevertheless can have profound detrimental impacts on society (e.g., heat-related impacts on human health, desiccation of croplands, increased fire hazard), while at the longest time scales it can extend over decades and can lead to long term structural changes in many aspects of society (e.g., agriculture, water resources, wetlands, tourism, population shifts). There is now considerable evidence that sea surface temperatures (SSTs) play a leading role in the development of drought world-wide, especially at seasonal and longer time scales, though land-atmosphere feedbacks can also play an important role. At shorter (subseasonal) time scales, SSTs are less important, but land feedbacks can play a critical role in maintaining and amplifying the atmospheric conditions associated with heat waves and short-term droughts. This talk reviews our current understanding of the physical mechanisms that drive precipitation and temperature variations on subseasonal to centennial time scales. This includes an assessment of predictability, prediction skill, and user needs at all time scales.

  12. The Effect of Detonation Wave Incidence Angle on the Acceleration of Flyers by Explosives Heavily Laden with Inert Additives

    NASA Astrophysics Data System (ADS)

    Loiseau, Jason; Georges, William; Frost, David; Higgins, Andrew

    2015-06-01

    The incidence angle of a detonation wave is often assumed to weakly influence the terminal velocity of an explosively driven flyer. For explosives heavily loaded with dense additives, this may not be true due to differences in momentum and energy transfer between detonation products, additive particles, and the flyer. For tangential incidence the particles are first accelerated against the flyer via an expansion fan, whereas they are first accelerated by the detonation wave in the normal case. In the current study we evaluate the effect of normal versus tangential incidence on the acceleration of flyers by nitromethane heavily loaded with a variety of additives. Normal detonation was initiated via an explosively driven slapper. Flyer acceleration was measured with heterodyne laser interferometry (PDV). The influence of wave angle is evaluated by comparing the terminal velocity in the two cases (i.e., normal and grazing) for the heavily loaded mixtures. The decrement in flyer velocity correlated primarily with additive volume fraction and had a weak dependence on additive density or particle size. The Gurney energy of the heterogeneous explosive was observed to increase with flyer mass, presumably due to the timescale over which impinging particles could transfer momentum.

  13. Effects of silicic spheres for the suppression of radiation heating using on electromagnetic wave scattering theory

    NASA Astrophysics Data System (ADS)

    Ohkawa, E.; Mikada, H.; Goto, T.; Takekawa, J.; Onishi, K.; Taniguchi, K.; Ashida, Y.

    2009-12-01

    The temperature of external materials of buildings rises when they are exposed to sunlight, and the room temperature rises too if the buildings’ external wall is in the sunlight. Therefore the crisis of electric power supply is frequently caused by air conditioning in midsummer. Recently, it has been experimentally confirmed that such temperature rising of such building materials may be suppressed when they are coated with paint including fine silicic spheres whose diameters are in micron to submicron scale. So we are able to reduce the energy consumption if room temperature is controlled not with any air conditioning but with these paints, and the heat island effects would be lowered. However, the mechanism of this temperature suppression has not been investigated. Experimental consideration of this paint has been done, but the mechanism how the paint controls the temperature rise has hardly been clarified theoretically. Since the best composition of the spheres and their best size are not understood well, it is necessary to theoretically clarify the controlling mechanism for the temperature rise to develop efficient paint. In this study, we aimed to find out the mechanism of the temperature suppression. When the electromagnetic wave at a frequency near eigenfrequencies of atoms, molecules or bindings enters the atoms or the molecules, they resonate and move intensely, and finally rise the temperature. Therefore, we presume that the temperature rise could be controlled if the electromagnetic waves around the eigenfrequencies could be removed. Here, we consider electromagnetic wave of light. Then we assumed that the electromagnetic waves in a certain range of frequencies were scattered to shield the radiated heat energy in the insolation and that the transmitted light through the paint layer is weakened. For verifying the hypotheses and finding the range of effective size, we used the Mie theory of a light scattering theory to calculate the intensity of scattered

  14. MAGNETOHYDRODYNAMIC WAVES AND CORONAL HEATING: UNIFYING EMPIRICAL AND MHD TURBULENCE MODELS

    SciTech Connect

    Sokolov, Igor V.; Van der Holst, Bart; Oran, Rona; Jin, Meng; Manchester, Ward B. IV; Gombosi, Tamas I.; Downs, Cooper; Roussev, Ilia I.; Evans, Rebekah M.

    2013-02-10

    We present a new global model of the solar corona, including the low corona, the transition region, and the top of the chromosphere. The realistic three-dimensional magnetic field is simulated using the data from the photospheric magnetic field measurements. The distinctive feature of the new model is incorporating MHD Alfven wave turbulence. We assume this turbulence and its nonlinear dissipation to be the only momentum and energy source for heating the coronal plasma and driving the solar wind. The difference between the turbulence dissipation efficiency in coronal holes and that in closed field regions is because the nonlinear cascade rate degrades in strongly anisotropic (imbalanced) turbulence in coronal holes (no inward propagating wave), thus resulting in colder coronal holes, from which the fast solar wind originates. The detailed presentation of the theoretical model is illustrated with the synthetic images for multi-wavelength EUV emission compared with the observations from SDO AIA and STEREO EUVI instruments for the Carrington rotation 2107.

  15. Electron Cyclotron / Bernstein Wave Heating and Current Drive Experiments using Phased-array Antenna in QUEST

    SciTech Connect

    Idei, H.; Zushi, H.; Hanada, K.; Nakamura, K.; Fujisawa, A.; Hasegawa, M.; Yoshida, N.; Watanebe, H.; Tokunaga, K.; Nagashima, Y.; Kawasaki, S.; Nakashima, H.; Higashijima, A.; Sakamoto, M.; Ejiri, A.; Takase, Y.; Sakaguchi, M.; Kalinnikova, E.; Ishiguro, M.; Tashima, S.

    2011-12-23

    The phased-array antenna system for Electron Cyclotron/Bernstein Wave Heating and Current Drive experiments has been developed in the QUEST. The antenna was designed to excite a pure O-mode wave in the oblique injection for the O-X-B mode conversion experiments, and its good performances were confirmed at a low power level. The plasma current (<{approx}15 kA) with an aspect ratio of 1.5 was started up and sustained by only RF injection in the low-density operations. The long pulse discharge of 10 kA was also attained for 37 s. The new density window to sustain the plasma current was observed in the high-density plasmas. The single-null divertor configuration with the high plasma current (<{approx}25 kA) was attained in the 17 s plasma sustainment.

  16. Heating of Sunspot Chromospheres by Slow-mode Acoustic Shock Waves

    NASA Astrophysics Data System (ADS)

    Lee, Myung Gyoon; Yun, Hong Sik

    1985-06-01

    Making use of the arbitrary shock theory developed by Ulmschneider (1967, 1971) and Ulmscneider and Kalkofen (1978), we have calculated the dissipation rates of upward-traveling slow-mode acoustic shock waves in umbral chromospheres for two umbral chromosphere models, a plateau model by Avrett (1981) and a gradient model by Yun and Beebe (1984). The computed shock dissipation rates are compared with the radiative cooling rate given by Avrett(1981). The results show that the slow-mode acoustic shock waves with a period of about 20 seconds can heat the low umbral chromospheres traveling with a mechanical energy flux of 2.6*10^6 erg/cm^2s at a height of 300-400 km above the temperature minimum region.

  17. Overly persistent circulation in climate models contributes to overestimated frequency and duration of heat waves and cold spells

    NASA Astrophysics Data System (ADS)

    Plavcova, Eva; Kysely, Jan

    2016-04-01

    The study examines links of summer heat waves and winter cold spells in Central Europe to atmospheric circulation and specifically its persistence in an ensemble of regional climate models (RCMs). We analyse 13 RCMs driven by the ERA-40 reanalysis and compare them against observations over 1971-2000. Using objective classification of circulation types and an efficiency coefficient with a block resampling test, we identify circulation types significantly conducive to heat waves and cold spells. We show that the RCMs have a stronger tendency to group together days with very high or low temperature and tend to simulate too many heat waves and cold spells, especially those lasting 5 days and more. Circulation types conducive to heat waves in summer are characterized by anticyclonic, southerly and easterly flow, with increasing importance of warm advection during heat waves. Winter cold spells are typically associated with easterly and anticyclonic flow, and the onset of cold spells tends to be linked to northerly and cyclonic flow with cold advection. The RCMs are generally able to reproduce the links between circulation and