Science.gov

Sample records for aircraft icing conditions

  1. The influence of ice accretion physics on the forecasting of aircraft icing conditions

    NASA Technical Reports Server (NTRS)

    Hansman, R. John, Jr.

    1990-01-01

    The physics which control aircraft ice accretion are reviewed in the context of identifying and forecasting hazardous icing conditions. The severity of aircraft icing is found to be extremely sensitive to temperature, liquid water content and droplet size distribution particularly near the transition between rime and mixed icing. The difficulty in measurement and the variability of these factors with altitude, position and time coupled with variable aircraft sensitivity make forecasting and identifying icing conditions difficult. Automated Pilot Reports (PIREPS) are suggested as one mechanism for improving the data base necessary to forecast icing conditions.

  2. Weather Features Associated with Aircraft Icing Conditions: A Case Study

    PubMed Central

    Fernández-González, Sergio; Sánchez, José Luis; Gascón, Estíbaliz; López, Laura; García-Ortega, Eduardo; Merino, Andrés

    2014-01-01

    In the context of aviation weather hazards, the study of aircraft icing is very important because of several accidents attributed to it over recent decades. On February 1, 2012, an unusual meteorological situation caused severe icing of a C-212-200, an aircraft used during winter 2011-2012 to study winter cloud systems in the Guadarrama Mountains of the central Iberian Peninsula. Observations in this case were from a MP-3000A microwave radiometric profiler, which acquired atmospheric temperature and humidity profiles continuously every 2.5 minutes. A Cloud Aerosol and Precipitation Spectrometer (CAPS) was also used to study cloud hydrometeors. Finally, ice nuclei concentration was measured in an isothermal cloud chamber, with the goal of calculating concentrations in the study area. Synoptic and mesoscale meteorological conditions were analysed using the Weather Research and Forecasting (WRF) model. It was demonstrated that topography influenced generation of a mesolow and gravity waves on the lee side of the orographic barrier, in the region where the aircraft experienced icing. Other factors such as moisture, wind direction, temperature, atmospheric stability, and wind shear were decisive in the appearance of icing. This study indicates that icing conditions may arise locally, even when the synoptic situation does not indicate any risk. PMID:24701152

  3. Weather features associated with aircraft icing conditions: a case study.

    PubMed

    Fernández-González, Sergio; Sánchez, José Luis; Gascón, Estíbaliz; López, Laura; García-Ortega, Eduardo; Merino, Andrés

    2014-01-01

    In the context of aviation weather hazards, the study of aircraft icing is very important because of several accidents attributed to it over recent decades. On February 1, 2012, an unusual meteorological situation caused severe icing of a C-212-200, an aircraft used during winter 2011-2012 to study winter cloud systems in the Guadarrama Mountains of the central Iberian Peninsula. Observations in this case were from a MP-3000A microwave radiometric profiler, which acquired atmospheric temperature and humidity profiles continuously every 2.5 minutes. A Cloud Aerosol and Precipitation Spectrometer (CAPS) was also used to study cloud hydrometeors. Finally, ice nuclei concentration was measured in an isothermal cloud chamber, with the goal of calculating concentrations in the study area. Synoptic and mesoscale meteorological conditions were analysed using the Weather Research and Forecasting (WRF) model. It was demonstrated that topography influenced generation of a mesolow and gravity waves on the lee side of the orographic barrier, in the region where the aircraft experienced icing. Other factors such as moisture, wind direction, temperature, atmospheric stability, and wind shear were decisive in the appearance of icing. This study indicates that icing conditions may arise locally, even when the synoptic situation does not indicate any risk. PMID:24701152

  4. Weather features associated with aircraft icing conditions: a case study.

    PubMed

    Fernández-González, Sergio; Sánchez, José Luis; Gascón, Estíbaliz; López, Laura; García-Ortega, Eduardo; Merino, Andrés

    2014-01-01

    In the context of aviation weather hazards, the study of aircraft icing is very important because of several accidents attributed to it over recent decades. On February 1, 2012, an unusual meteorological situation caused severe icing of a C-212-200, an aircraft used during winter 2011-2012 to study winter cloud systems in the Guadarrama Mountains of the central Iberian Peninsula. Observations in this case were from a MP-3000A microwave radiometric profiler, which acquired atmospheric temperature and humidity profiles continuously every 2.5 minutes. A Cloud Aerosol and Precipitation Spectrometer (CAPS) was also used to study cloud hydrometeors. Finally, ice nuclei concentration was measured in an isothermal cloud chamber, with the goal of calculating concentrations in the study area. Synoptic and mesoscale meteorological conditions were analysed using the Weather Research and Forecasting (WRF) model. It was demonstrated that topography influenced generation of a mesolow and gravity waves on the lee side of the orographic barrier, in the region where the aircraft experienced icing. Other factors such as moisture, wind direction, temperature, atmospheric stability, and wind shear were decisive in the appearance of icing. This study indicates that icing conditions may arise locally, even when the synoptic situation does not indicate any risk.

  5. Performance degradation of a typical twin engine commuter type aircraft in measured natural icing conditions

    NASA Technical Reports Server (NTRS)

    Ranaudo, R. J.; Mikkelsen, K. L.; Mcknight, R. C.; Perkins, P. J., Jr.

    1984-01-01

    The performance of an aircraft in various measured icing conditions was investigated. Icing parameters such as liquid water content, temperature, cloud droplet sizes and distributions were measured continuously while in icing. Flight data were reduced to provide plots of the aircraft drag polars and lift curves (CL vs. alpha) for the measured ""iced'' condition as referenced to the uniced aircraft. These data were also reduced to provide plots of thrust horsepower required vs. single engine power available to show how icing affects engine out capability. It is found that performance degradation is primarily influenced by the amount and shape of the accumulated ice. Glaze icing caused the greatest aerodynamic performance penalties in terms of increased drag and reduction in lift while aerodynamic penalties due to rime icing were significantly lower.

  6. Ice Shape Scaling for Aircraft in SLD Conditions

    NASA Technical Reports Server (NTRS)

    Anderson, David N.; Tsao, Jen-Ching

    2008-01-01

    This paper has summarized recent NASA research into scaling of SLD conditions with data from both SLD and Appendix C tests. Scaling results obtained by applying existing scaling methods for size and test-condition scaling will be reviewed. Large feather growth issues, including scaling approaches, will be discussed briefly. The material included applies only to unprotected, unswept geometries. Within the limits of the conditions tested to date, the results show that the similarity parameters needed for Appendix C scaling also can be used for SLD scaling, and no additional parameters are required. These results were based on visual comparisons of reference and scale ice shapes. Nearly all of the experimental results presented have been obtained in sea-level tunnels. The currently recommended methods to scale model size, icing limit and test conditions are described.

  7. Nowcasting Aircraft Icing Conditions in the Presence of Multilayered Clouds Using Meteorological Satellite Data

    NASA Technical Reports Server (NTRS)

    Spangenberg, Douglas A.; Minnis, Patrick; Smith, William L.; Chang, Fu-Lung

    2011-01-01

    Cloud properties retrieved from satellite data are used to diagnose aircraft icing threat in single layer and multilayered ice-over-liquid clouds. The algorithms are being applied in real time to the Geostationary Operational Environmental Satellite (GOES) data over the CONUS with multilayer data available over the eastern CONUS. METEOSAT data are also used to retrieve icing conditions over western Europe. The icing algorithm s methodology and validation are discussed along with future enhancements and plans. The icing risk product is available in image and digital formats on NASA Langley s Cloud and Radiation Products web site, http://wwwangler. larc.nasa.gov.

  8. Subsonic Aircraft Safety Icing Study

    NASA Technical Reports Server (NTRS)

    Jones, Sharon Monica; Reveley, Mary S.; Evans, Joni K.; Barrientos, Francesca A.

    2008-01-01

    NASA's Integrated Resilient Aircraft Control (IRAC) Project is one of four projects within the agency s Aviation Safety Program (AvSafe) in the Aeronautics Research Mission Directorate (ARMD). The IRAC Project, which was redesigned in the first half of 2007, conducts research to advance the state of the art in aircraft control design tools and techniques. A "Key Decision Point" was established for fiscal year 2007 with the following expected outcomes: document the most currently available statistical/prognostic data associated with icing for subsonic transport, summarize reports by subject matter experts in icing research on current knowledge of icing effects on control parameters and establish future requirements for icing research for subsonic transports including the appropriate alignment. This study contains: (1) statistical analyses of accident and incident data conducted by NASA researchers for this "Key Decision Point", (2) an examination of icing in other recent statistically based studies, (3) a summary of aviation safety priority lists that have been developed by various subject-matter experts, including the significance of aircraft icing research in these lists and (4) suggested future requirements for NASA icing research. The review of several studies by subject-matter experts was summarized into four high-priority icing research areas. Based on the Integrated Resilient Aircraft Control (IRAC) Project goals and objectives, the IRAC project was encouraged to conduct work in all of the high-priority icing research areas that were identified, with the exception of the developing of methods to sense and document actual icing conditions.

  9. The measurement of aircraft performance and stability and control after flight through natural icing conditions

    NASA Technical Reports Server (NTRS)

    Ranaudo, R. J.; Mikkelsen, K. L.; Mcknight, R. C.; Ide, R. F.; Reehorst, A. L.; Jordan, J. L.; Schinstock, W. C.; Platz, S. J.

    1986-01-01

    The effects of airframe icing on the performance and stability and control of a twin-engine commuter-class aircraft were measured by the NASA Lewis Research Center. This work consisted of clear air tests with artificial ice shapes attached to the horizontal tail, and natural icing flight tests in measured icing clouds. The clear air tests employed static longitudinal flight test methods to determine degradation in stability margins for four simulated ice shapes. The natural icing flight tests employed a data acquisition system, which was provided under contract to NASA by Kohlman Systems Research Incorporated. This system used a performance modeling method and modified maximum likelihood estimation (MMLE) technique to determine aircraft performance degradation and stability and control. Flight test results with artificial ice shapes showed that longitudinal, stick-fixed, static margins are reduced on the order of 5 percent with flaps up. Natural icing tests with the KSR system corroborated these results and showed degradation in the elevator control derivatives on the order of 8 to 16 percent depending on wing flap configuration. Performance analyses showed the individual contributions of major airframe components to the overall degration in lift and drag.

  10. The measurement of aircraft performance and stability and control after flight through natural icing conditions

    NASA Technical Reports Server (NTRS)

    Ranaudo, R. J.; Mikkelsen, K. L.; Mcknight, R. C.; Ide, R. F.; Reehorst, A. L.

    1986-01-01

    The effects of airframe icing on the performance and stability and control of a twin-engine commuter-class aircraft were measured by the NASA Lewis Research Center. This work consisted of clear air tests with artificial ice shapes attached to the horizontal tail, and natural icing flight tests in measured icing clouds. The clear air tests employed static longitudinal flight test methods to determine degradation in stability margins for four simulated ice shapes. The natural icing flight tests employed a data acquisition system, which was provided under contract to NASA by Kohlman Systems Research Incorporated. This system used a performance modeling method and modified maximum likelihood estimation (MMLE) technique to determine aircraft performance degradation and stability and control. Flight test results with artificial ice shapes showed that longitudinal, stick-fixed, static margins are reduced on the order of 5 percent with flaps up. Natural icing tests with the KSR system corroborated these results and showed degradation in the elevator control derivatives on the order of 8 to 16 percent depending on wing flap configuration. Performance analyses showed the individual contributions of major airframe components to the overall degradation in lift and drag.

  11. Aircraft icing research at NASA

    NASA Technical Reports Server (NTRS)

    Reinmann, J. J.; Shaw, R. J.; Olsen, W. A., Jr.

    1982-01-01

    Research activity is described for: ice protection systems, icing instrumentation, experimental methods, analytical modeling for the above, and in flight research. The renewed interest in aircraft icing has come about because of the new need for All-Weather Helicopters and General Aviation aircraft. Because of increased fuel costs, tomorrow's Commercial Transport aircraft will also require new types of ice protection systems and better estimates of the aeropenalties caused by ice on unprotected surfaces. The physics of aircraft icing is very similar to the icing that occurs on ground structures and structures at sea; all involve droplets that freeze on the surfaces because of the cold air. Therefore all icing research groups will benefit greatly by sharing their research information.

  12. National plans for aircraft icing and improved aircraft icing forecasts and associated warning services

    NASA Technical Reports Server (NTRS)

    Pass, Ralph P.

    1988-01-01

    Recently, the United States has increased its activities related to aircraft icing in numerous fields: ice phobics, revised characterization of icing conditions, instrument development/evaluation, de-ice/anti-ice devices, simulated supercooled clouds, computer simulation and flight tests. The Federal Coordinator for Meteorology is involved in two efforts, one a National Plan on Aircraft Icing and the other a plan for Improved Aircraft Icing Forecasts and Associated Warning Services. These two plans will provide an approved structure for future U.S. activities related to aircraft icing. The recommended activities will significantly improve the position of government agencies to perform mandated activities and to enable U.S. manufacturers to be competitive in the world market.

  13. Aircraft observations of the evolution of ice surface conditions at the onset of the melt season in the Beaufort Sea

    NASA Astrophysics Data System (ADS)

    Birnbaum, G.; Ehrlich, A.; Schwarz, P.; Lüpkes, C.; Dierking, W.; Hartmann, J.

    2012-12-01

    At the onset of the melt season in the Arctic, the energy exchange between atmosphere, sea ice, and ocean undergoes strong changes. Caused by melting of snow and formation of melt ponds and open leads the areally averaged albedo decreases dramatically and absorption of solar radiation is enhanced. To investigate these changes, the aircraft campaign MELTEX was performed from 11 May to 7 June, 2008 over the Beaufort Sea (region 69°N-74°N, 133°W-144°W). During the campaign, the sea ice cover experienced several episodes with strong on-ice warm-air advection from the Canadian Coast. Between these warm episodes, northerly flow with cold-air advection from the inner Arctic caused an interruption of melting and melt pond evolution and even a temporary refreezing. To quantify the evolution of ice surface conditions, the aircraft POLAR 5 was equipped with a digital reflex camera, broadband radiation sensors, a spectral albedometer with active horizontal stabilization, and further meteorological instruments. Images of seven flights were analyzed by means of a supervised classification employing the maximum likelihood method to derive the areal fraction of different surface classes. Areally averaged broadband and spectral albedo was derived for clear-sky conditions only to allow for a better comparison of values. On 11 May, the ice conditions were still characteristic for late winter. The maximum broadband albedo for snow covered ice was 0.82. On 26 May, already 21,6% of the sea ice surface right north of a coastal polynya consisted of wet ice (19,4%) and shallow melt ponds (2,2%). Broadband albedo measurements indicated an average value of 0.57 for melting snow and bare ice. The most enhanced stage of melting was encountered on 6 June for fast ice in Franklin and Darnley Bay, south of the Amundsen Gulf. The total fraction of melt ponds and particle-laden sea ice amounted to 45,0±16,7% with an average broadband albedo of 0.16. The average albedo of the remaining clean

  14. NASA's aircraft icing analysis program

    NASA Technical Reports Server (NTRS)

    Shaw, R. J.

    1986-01-01

    An overview of the NASA ongoing efforts to develop an aircraft icing analysis capability is presented. Discussions are included of the overall and long term objectives of the program as well as current capabilities and limitations of the various computer codes being developed. Descriptions are given of codes being developed to analyze two- and three-dimensional trajectories of water droplets, airfoil ice accretion, aerodynamic performance degradation of components and complete aircraft configurations, electrothermal deicer, fluid freezing point depressant antideicer and electro-impulse deicer. The need for bench mark and verification data to support the code development is also discussed, and selected results of experimental programs are presented.

  15. NASA's Aircraft Icing Analysis Program

    NASA Technical Reports Server (NTRS)

    Shaw, R. J.

    1986-01-01

    An overview of the NASA ongoing efforts to develop an aircraft icing analysis capability is presented. Discussions are included of the overall and long term objectives of the program as well as current capabilities and limitations of the various computer codes being developed. Descriptions are given of codes being developed to analyze two and three dimensional trajectories of water droplets, airfoil ice accretion, aerodynamic performance degradation of components and complete aircraft configurations, electrothermal deicer, fluid freezing point depressant antideicer and electro-impulse deicer. The need for bench mark and verification data to support the code development is also discussed, and selected results of experimental programs are presented.

  16. In-flight detection and identification and accommodation of aircraft icing

    NASA Astrophysics Data System (ADS)

    Caliskan, Fikret; Hajiyev, Chingiz

    2012-11-01

    The recent improvements and research on aviation have focused on the subject of aircraft safe flight even in the severe weather conditions. As one type of such weather conditions, aircraft icing considerably has negative effects on the aircraft flight performance. The risks of the iced aerodynamic surfaces of the flying aircraft have been known since the beginning of the first flights. Until recent years, as a solution for this event, the icing conditions ahead flight route are estimated from radars or other environmental sensors, hence flight paths are changed, or, if it exists, anti-icing/de-icing systems are used. This work aims at the detection and identification of airframe icing based on statistical properties of aircraft dynamics and reconfigurable control protecting aircraft from hazardous icing conditions. In this paper, aircraft icing identification based on neural networks is investigated. Following icing identification, reconfigurable control is applied for protecting the aircraft from hazardous icing conditions.

  17. The NASA aircraft icing research program

    NASA Technical Reports Server (NTRS)

    Shaw, Robert J.; Reinmann, John J.

    1990-01-01

    The objective of the NASA aircraft icing research program is to develop and make available to industry icing technology to support the needs and requirements for all-weather aircraft designs. Research is being done for both fixed wing and rotary wing applications. The NASA program emphasizes technology development in two areas, advanced ice protection concepts and icing simulation. Reviewed here are the computer code development/validation, icing wind tunnel testing, and icing flight testing efforts.

  18. Investigation of Meteorological Conditions Associated with Aircraft Icing in Layer-Type Clouds for 1947-48 Winter

    NASA Technical Reports Server (NTRS)

    Kline, Dwight B

    1949-01-01

    Rotating-cylinder measurements of the icing conditions encountered in flight during the winter of 1947-48 are presented. Liquid water content, drop size, and temperature data are shown to be consistent with previously measured conditions and with proposed maximum icing conditions in supercooled layer-type clouds. Cumulative frequency graphs of meteorological parameters indicate the frequency with which various icing conditions have been encountered in the Great Lakes area and surrounding states.

  19. Antifreeze Polysaccharide Coating Study for De-icing Aircraft

    NASA Astrophysics Data System (ADS)

    Morita, Katsuaki; Sakaue, Hirotaka; Ando, Azuma; Matsuda, Yoshiyuki; Kawahara, Hidehisa

    2015-11-01

    Anti-icing or deicing of an aircraft is necessary for a safe flight operation. Mechanical processes, such as heating and deicer boot, are widely used. Deicing fluids, such as propyrene glycol and ethylene glycol, are used to coat the aircraft. However, these should be coated every time before the take-off, since the fluids come off from the aircraft while cruising. We study an antifreeze polysaccharide (AFPS) coating as a deicer for an aircraft. It is designed to coat on the aircraft without removal. Since an AFPS coating removes ice by reducing the interfacial energy, it would be an alternative way to prevent ice on the aircraft. We provide a temperature-controlled room, which can control its temperature under icing conditions (-8 and -4 °C). Ice adhesion tests are performed for AFPS coating and compared with a fundamental specimen without the coating.

  20. Instrument for Aircraft-Icing and Cloud-Physics Measurements

    NASA Technical Reports Server (NTRS)

    Lilie, Lyle; Bouley, Dan; Sivo, Chris

    2006-01-01

    The figure shows a compact, rugged, simple sensor head that is part of an instrumentation system for making measurements to characterize the severity of aircraft-icing conditions and/or to perform research on cloud physics. The quantities that are calculated from measurement data acquired by this system and that are used to quantify the severity of icing conditions include sizes of cloud water drops, cloud liquid water content (LWC), cloud ice water content (IWC), and cloud total water content (TWC). The sensor head is mounted on the outside of an aircraft, positioned and oriented to intercept the ambient airflow. The sensor head consists of an open housing that is heated in a controlled manner to keep it free of ice and that contains four hot-wire elements. The hot-wire sensing elements have different shapes and sizes and, therefore, exhibit different measurement efficiencies with respect to droplet size and water phase (liquid, frozen, or mixed). Three of the hot-wire sensing elements are oriented across the airflow so as to intercept incoming cloud water. For each of these elements, the LWC or TWC affects the power required to maintain a constant temperature in the presence of cloud water.

  1. Simulation Tools Model Icing for Aircraft Design

    NASA Technical Reports Server (NTRS)

    2012-01-01

    Here s a simple science experiment to try: Place an unopened bottle of distilled water in your freezer. After 2-3 hours, if the water is pure enough, you will notice that it has not frozen. Carefully pour the water into a bowl with a piece of ice in it. When it strikes the ice, the water will instantly freeze. One of the most basic and commonly known scientific facts is that water freezes at around 32 F. But this is not always the case. Water lacking any impurities for ice crystals to form around can be supercooled to even lower temperatures without freezing. High in the atmosphere, water droplets can achieve this delicate, supercooled state. When a plane flies through clouds containing these droplets, the water can strike the airframe and, like the supercooled water hitting the ice in the experiment above, freeze instantly. The ice buildup alters the aerodynamics of the plane - reducing lift and increasing drag - affecting its performance and presenting a safety issue if the plane can no longer fly effectively. In certain circumstances, ice can form inside aircraft engines, another potential hazard. NASA has long studied ways of detecting and countering atmospheric icing conditions as part of the Agency s efforts to enhance aviation safety. To do this, the Icing Branch at Glenn Research Center utilizes a number of world-class tools, including the Center s Icing Research Tunnel and the NASA 607 icing research aircraft, a "flying laboratory" for studying icing conditions. The branch has also developed a suite of software programs to help aircraft and icing protection system designers understand the behavior of ice accumulation on various surfaces and in various conditions. One of these innovations is the LEWICE ice accretion simulation software. Initially developed in the 1980s (when Glenn was known as Lewis Research Center), LEWICE has become one of the most widely used tools in icing research and aircraft design and certification. LEWICE has been transformed over

  2. Aircraft icing instrumentation: Unfilled needs. [rotary wing aircraft

    NASA Technical Reports Server (NTRS)

    Kitchens, P. F.

    1980-01-01

    A list of icing instrumentation requirements are presented. Because of the Army's helicopter orientation, many of the suggestions are specific to rotary wing aircraft; however, some of the instrumentation are also suitable for general aviation aircraft.

  3. Report on ice formation on aircraft

    NASA Technical Reports Server (NTRS)

    1939-01-01

    The physical phenomena involved in the icing of aircraft have been analyzed and measured. Recommendations on warning devices are made as well as the different types of ice and glazing that can occur on airplanes are examined and discussed.

  4. Aircraft Icing Weather Data Reporting and Dissemination System

    NASA Technical Reports Server (NTRS)

    Bass, Ellen J.; Minsk, Brian; Lindholm, Tenny; Politovich, Marcia; Reehorst, Andrew (Technical Monitor)

    2002-01-01

    The long-term operational concept of this research is to develop an onboard aircraft system that assesses and reports atmospheric icing conditions automatically and in a timely manner in order to improve aviation safety and the efficiency of aircraft operations via improved real-time and forecast weather products. The idea is to use current measurement capabilities on aircraft equipped with icing sensors and in-flight data communication technologies as a reporting source. Without requiring expensive avionics upgrades, aircraft data must be processed and available for downlink. Ideally, the data from multiple aircraft can then be integrated (along with other real-time and modeled data) on the ground such that aviation-centered icing hazard metrics for volumes of airspace can be assessed. As the effect of icing on different aircraft types can vary, the information should be displayed in meaningful ways such that multiple types of users can understand the information. That is, information must be presented in a manner to allow users to understand the icing conditions with respect to individual concerns and aircraft capabilities. This research provides progress toward this operational concept by: identifying an aircraft platform capable of digitally capturing, processing, and downlinking icing data; identifying the required in situ icing data processing; investigating the requirements for routing the icing data for use by weather products; developing an icing case study in order to gain insight into major air carrier needs; developing and prototyping icing display concepts based on the National Center for Atmospheric Research's existing diagnostic and forecast experimental icing products; and conducting a usability study for the prototyped icing display concepts.

  5. Remote sensing of potential aircraft icing areas

    NASA Astrophysics Data System (ADS)

    Zuev, Vladimir V.; Nakhtigalova, Daria P.; Shelekhov, Alexander P.; Shelekhova, Evgeniya A.; Baranov, Nikolay A.; Kizhner, Lubov I.

    2015-11-01

    Remote sensing technique of detection of potential aircraft icing areas based on temperature profile measurements, using meteorological temperature profiler, and the data of the Airfield Measuring and Information System (AMIS-RF), was proposed, theoretically described and experimentally validated during the field project in 2012 - 2013 in the Tomsk Bogashevo Airport. Spatial areas of potential aircraft icing were determined using the RAP algorithm and Godske formula. The equations for the reconstruction of profiles of relative humidity and dew point using data from AMIS-RF are given. Actual data on the aircraft icing for the Tomsk Bogashevo Airport on 11 October 2012 and 17 March 2013 are presented in this paper. The RAP algorithm and Godske formula show similar results for the location of spatial areas of potential icing. Though, the results obtained using the RAP algorithm are closer to the actual data on the icing known from aircraft crew reports.

  6. Hydrophobic coating study for anti-icing aircraft

    NASA Astrophysics Data System (ADS)

    Morita, Katsuaki; Aoki, Akihito; Konno, Akihisa; Sakaue, Hirotaka

    2010-11-01

    Anti-icing or deicing of an aircraft is necessary for a safe flight operation. Mechanical processes, such as heating and deicer boot, are widely used. Deicing fluids, such as ethylene glycol type, are used to coat the aircraft. However, these should be coated every time before the take-off, since the fluids come off from the aircraft while cruising. We study a hydrophobic coating as a anti-icing for an aircraft. It is designed to coat the aircraft without removal. Since a hydrophobic coating prevents water by reducing the surface energy, it would be another way to prevent ice on the aircraft. We provide a temperature-controlled room, which can control its temperature at an icing condition (-10 to 0 degrees C). The contact angle is tested for various hydrophobic coatings. A water jet impingement on a hydrophobic-coated plate is included. The jet freezes under the icing condition. Qualitative comparison among various hydrophobic coatings as anti-icing is discussed.

  7. Microwave System for Detecting Ice on Aircraft

    NASA Technical Reports Server (NTRS)

    Joseph, Philip J.; Glynn, Dennis P., Jr.; Joseph, John C.

    2004-01-01

    A microwave-based system has been developed as a means of detecting ice on aircraft surfaces, with enough sensitivity to provide a warning before the ice accretes to a dangerous thickness. The system can measure the thickness of ice from a few mils (1 mil = 0.0254 mm) to about 1/4 in. (.6 mm) and can distinguish among (1) ice, (2) water (or deicing fluid), and (3) a mixture of ice and water (or deicing fluid). Sensors have been ruggedized to withstand the rain erosion environment.

  8. Continuous measurement of aircraft wing icing

    NASA Technical Reports Server (NTRS)

    Yao, Stephen S. C.

    1994-01-01

    Ice formation on the wings of aircraft is a problem that has plagued air travel since its inception. Several recent incidents have been attributed to ice formation on the lifting surfaces of wings. This paper describes a SBIR Phase 1 research effort on the use of small flat dielectric sensors in detecting a layer of ice above the sensor. The sensors are very small, lightweight, and inexpensive. The electronics package that controls the sensor is also small, and could be even smaller using commonly available miniaturization technologies. Thus, several sensors could be placed on a surface such that a representative ice thickness profile could be measured. The benefits offered by developing this technology go beyond the safety improvements realized by monitoring ice formation on the wings of an aircraft. Continuous monitoring of anti-icing fluid concentrations on the ground would warn the pilot of impending fluid failure as well as allowing the stations to use less de-icing solution per aircraft. This in turn would increase the safety of takeoffs and reduce the overall discharge of de-icing solution into the environment, thus reducing the biohazard of the de-icing procedure.

  9. Ultrasonic techniques for aircraft ice accretion measurement

    NASA Technical Reports Server (NTRS)

    Hansman, R. John, Jr.; Kirby, Mark S.; Lichtenfelts, Fred

    1990-01-01

    Results of tests to measure ice growth in natural (flight) and artificial (icing wind tunnel) icing conditions are presented. Ice thickness is measured using an ultrasonic pulse-echo technique. Two icing regimes, wet and dry ice growth, are identified and the unique ultrasonic signal characteristics associated with these different types of ice growth are described. Ultrasonic measurements of ice growth on cylinders and airfoils exposed to artificial and natural icing conditions are presented. An accuracy of plus or minus 0.5 mm is achieved for ice thickness measurement using the pulse-echo technique. The performance of two-probe type ice detectors is compared to the surface mounted ultrasonic system. The ultrasonically measured ice accretion rates and ice surface condition (wet or dry) are used to compare the heat transfer characteristics for flight and icing wind tunnel environments. In general the heat transfer coefficient is inferred to be higher in the wind tunnel environment, not likely due to higher freestream turbulence levels. Finally, preliminary results of tests to measure ice growth on airfoil using an array of ultrasonic transducers are described. Ice profiles obtained during flight in natural icing conditions are shown and compared with mechanical and stereo image measurements.

  10. Structural properties of impact ices accreted on aircraft structures

    NASA Technical Reports Server (NTRS)

    Scavuzzo, R. J.; Chu, M. L.

    1987-01-01

    The structural properties of ice accretions formed on aircraft surfaces are studied. The overall objectives are to measure basic structural properties of impact ices and to develop finite element analytical procedures for use in the design of all deicing systems. The Icing Research Tunnel (IRT) was used to produce simulated natural ice accretion over a wide range of icing conditions. Two different test apparatus were used to measure each of the three basic mechanical properties: tensile, shear, and peeling. Data was obtained on both adhesive shear strength of impact ices and peeling forces for various icing conditions. The influences of various icing parameters such as tunnel air temperature and velocity, icing cloud drop size, material substrate, surface temperature at ice/material interface, and ice thickness were studied. A finite element analysis of the shear test apparatus was developed in order to gain more insight in the evaluation of the test data. A comparison with other investigators was made. The result shows that the adhesive shear strength of impact ice typically varies between 40 and 50 psi, with peak strength reaching 120 psi and is not dependent on the kind of substrate used, the thickness of accreted ice, and tunnel temperature below 4 C.

  11. Progress Towards the Remote Sensing of Aircraft Icing Hazards

    NASA Technical Reports Server (NTRS)

    Reehorst, Andrew; Brinker, David; Politovich, Marcia; Serke, David; Ryerson, Charles; Pazmany, Andrew; Solheim, Fredrick

    2009-01-01

    NASA has teamed with the FAA, DoD, industry, and academia for research into the remote detection and measurement of atmospheric conditions leading to aircraft icing hazards. The ultimate goal of this effort is to provide pilots, controllers, and dispatchers sufficient information to allow aircraft to avoid or minimize their exposure to the hazards of in-flight icing. Since the hazard of in-flight icing is the outcome of aircraft flight through clouds containing supercooled liquid water and strongly influenced by the aircraft s speed and configuration and by the length of exposure, the hazard cannot be directly detected, but must be inferred based upon the measurement of conducive atmospheric conditions. Therefore, icing hazard detection is accomplished through the detection and measurement of liquid water in regions of measured sub-freezing air temperatures. The icing environment is currently remotely measured from the ground with a system fusing radar, lidar, and multifrequency microwave radiometer sensors. Based upon expected ice accretion severity for the measured environment, a resultant aircraft hazard is then calculated. Because of the power, size, weight, and view angle constraints of airborne platforms, the current ground-based solution is not applicable for flight. Two current airborne concepts are based upon the use of either multifrequency radiometers or multifrequency radar. Both ground-based and airborne solutions are required for the future since groundbased systems can provide hazard detection for all aircraft in airport terminal regions while airborne systems will be needed to provide equipped aircraft with flight path coverage between terminal regions.

  12. Ultrasonic techniques for aircraft ice accretion measurement

    NASA Technical Reports Server (NTRS)

    Hansman, R. John, Jr.; Kirby, Mark S.; Lichtenfelts, Fred

    1988-01-01

    Ultrasonic pulse-echo measurements of ice growth on cylinders and airfoils exposed to both artificial (icing wind tunnel) and natural (flight) icing conditions are presented. An accuracy of + or - 0.5 mm is achieved with the present method. The ultrasonic signal characteristics associated with each of the two types of icing regimes identified, wet and dry ice growth, are discussed. Heat transfer coefficients are found to be higher in the wind tunnel environment than in flight. Results for ice growth on airfoils have also been obtained using an array of ultrasonic transducers. Icing profiles obtained during flight are compared with mechanical and stereo image measurements.

  13. Diagnosing Aircraft Icing Potential from Satellite Cloud Retrievals

    NASA Technical Reports Server (NTRS)

    Smith, William L., Jr.; Minnis, Patrick; Fleeger, Cecilia; Spangenberg, Douglas

    2013-01-01

    The threat for aircraft icing in clouds is a significant hazard that routinely impacts aviation operations. Accurate diagnoses and forecasts of aircraft icing conditions requires identifying the location and vertical distribution of clouds with super-cooled liquid water (SLW) droplets, as well as the characteristics of the droplet size distribution. Traditional forecasting methods rely on guidance from numerical models and conventional observations, neither of which currently resolve cloud properties adequately on the optimal scales needed for aviation. Satellite imagers provide measurements over large areas with high spatial resolution that can be interpreted to identify the locations and characteristics of clouds, including features associated with adverse weather and storms. This paper describes new techniques for interpreting cloud products derived from satellite data to infer the flight icing threat to aircraft. For unobscured low clouds, the icing threat is determined using empirical relationships developed from correlations between satellite imager retrievals of liquid water path and droplet size with icing conditions reported by pilots (PIREPS). For deep ice over water cloud systems, ice and liquid water content (IWC and LWC) profiles are derived by using the imager cloud properties to constrain climatological information on cloud vertical structure and water phase obtained apriori from radar and lidar observations, and from cloud model analyses. Retrievals of the SLW content embedded within overlapping clouds are mapped to the icing threat using guidance from an airfoil modeling study. Compared to PIREPS and ground-based icing remote sensing datasets, the satellite icing detection and intensity accuracies are approximately 90% and 70%, respectively, and found to be similar for both low level and deep ice over water cloud systems. The satellite-derived icing boundaries capture the reported altitudes over 90% of the time. Satellite analyses corresponding to

  14. Advanced instrumentation for aircraft icing research

    NASA Technical Reports Server (NTRS)

    Bachalo, W.; Smith, J.; Rudoff, R.

    1990-01-01

    A compact and rugged probe based on the phase Doppler method was evaluated as a means for characterizing icing clouds using airborne platforms and for advancing aircraft icing research in large scale wind tunnels. The Phase Doppler Particle Analyzer (PDPA) upon which the new probe was based is now widely recognized as an accurate method for the complete characterization of sprays. The prototype fiber optic-based probe was evaluated in simulated aircraft icing clouds and found to have the qualities essential to providing information that will advance aircraft icing research. Measurement comparisons of the size and velocity distributions made with the standard PDPA and the fiber optic probe were in excellent agreement as were the measurements of number density and liquid water content. Preliminary testing in the NASA Lewis Icing Research Tunnel (IRT) produced reasonable results but revealed some problems with vibration and signal quality at high speeds. The cause of these problems were identified and design changes were proposed to eliminate the shortcomings of the probe.

  15. Effects of ice accretions on aircraft aerodynamics

    NASA Astrophysics Data System (ADS)

    Lynch, Frank T.; Khodadoust, Abdollah

    2001-11-01

    This article is a systematic and comprehensive review, correlation, and assessment of test results available in the public domain which address the aerodynamic performance and control degradations caused by various types of ice accretions on the lifting surfaces of fixed wing aircraft. To help put the various test results in perspective, overviews are provided first of the important factors and limitations involved in computational and experimental icing simulation techniques, as well as key aerodynamic testing simulation variables and governing flow physics issues. Following these are the actual reviews, assessments, and correlations of a large number of experimental measurements of various forms of mostly simulated in-flight and ground ice accretions, augmented where appropriate by similar measurements for other analogous forms of surface contamination and/or disruptions. In-flight icing categories reviewed include the initial and inter-cycle ice accretions inherent in the use of de-icing systems which are of particular concern because of widespread misconceptions about the thickness of such accretions which can be allowed before any serious consequences occur, and the runback/ridge ice accretions typically associated with larger-than-normal water droplet encounters which are of major concern because of the possible potential for catastrophic reductions in aerodynamic effectiveness. The other in-flight ice accretion category considered includes the more familiar large rime and glaze ice accretions, including ice shapes with rather grotesque features, where the concern is that, in spite of all the research conducted to date, the upper limit of penalties possible has probably not been defined. Lastly, the effects of various possible ground frost/ice accretions are considered. The concern with some of these is that for some types of configurations, all of the normally available operating margins to stall at takeoff may be erased if these accretions are not

  16. 14 CFR 121.629 - Operation in icing conditions.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... safety of the flight. (b) No person may take off an aircraft when frost, ice, or snow is adhering to the... the takeoff would not be in compliance with paragraph (c) of this section. Takeoffs with frost under... conditions are such that frost, ice, or snow may reasonably be expected to adhere to the aircraft, unless...

  17. 14 CFR 121.629 - Operation in icing conditions.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... safety of the flight. (b) No person may take off an aircraft when frost, ice, or snow is adhering to the... the takeoff would not be in compliance with paragraph (c) of this section. Takeoffs with frost under... conditions are such that frost, ice, or snow may reasonably be expected to adhere to the aircraft, unless...

  18. 14 CFR 121.629 - Operation in icing conditions.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... safety of the flight. (b) No person may take off an aircraft when frost, ice, or snow is adhering to the... the takeoff would not be in compliance with paragraph (c) of this section. Takeoffs with frost under... conditions are such that frost, ice, or snow may reasonably be expected to adhere to the aircraft, unless...

  19. 14 CFR 121.629 - Operation in icing conditions.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... safety of the flight. (b) No person may take off an aircraft when frost, ice, or snow is adhering to the... the takeoff would not be in compliance with paragraph (c) of this section. Takeoffs with frost under... conditions are such that frost, ice, or snow may reasonably be expected to adhere to the aircraft, unless...

  20. 14 CFR 121.629 - Operation in icing conditions.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... safety of the flight. (b) No person may take off an aircraft when frost, ice, or snow is adhering to the... the takeoff would not be in compliance with paragraph (c) of this section. Takeoffs with frost under... conditions are such that frost, ice, or snow may reasonably be expected to adhere to the aircraft, unless...

  1. Contrail ice particles in aircraft wakes and their climatic importance

    NASA Astrophysics Data System (ADS)

    Schumann, Ulrich; JeßBerger, Philipp; Voigt, Christiane

    2013-06-01

    Measurements of gaseous (NO, NOy, SO2, HONO) and ice particle concentrations in young contrails in primary and secondary wakes of aircraft of different sizes (B737, A319, A340, A380) are used to investigate ice particle formation behind aircraft. The gas concentrations are largest in the primary wake and decrease with increasing altitude in the secondary wake, as expected for passive trace gases and aircraft-dependent dilution. In contrast, the measured ice particle concentrations were found larger in the secondary wake than in the primary wake. The contrails contain more ice particles than expected for previous black carbon (soot) estimates. The ice concentrations may result from soot-induced ice nucleation for a soot number emission index of 1015 kg-1. For a doubled ice particle concentration in young contrails, a contrail cirrus model computes about 60% increases of global radiative forcing by contrail cirrus because of simultaneous increases in optical depth, age, and cover.

  2. Selected bibliography of NACA-NASA aircraft icing publications

    NASA Technical Reports Server (NTRS)

    Reinmann, J. J. (Compiler)

    1981-01-01

    A summary of NACA-NASA icing research from 1940 to 1962 is presented. It includes: the main results of the NACA icing program from 1940 to 1950; a selected bibliography of 132 NACA-NASA aircraft icing publications; a technical summary of each document cited in the selected bibliography; and a microfiche copy of each document cited in the selected bibliography.

  3. Development of an ultrasonic pulse-echo (UPE) technique for aircraft icing studies

    SciTech Connect

    Liu, Yang; Hu, Hui; Chen, Wen-Li; Bond, Leonard J.

    2014-02-18

    Aircraft operating in some cold weather conditions face the risk of icing. Icing poses a threat to flight safety and its management is expensive. Removing light frost on a clear day from a medium-size business jet can cost $300, heavy wet snow removal can cost $3,000 and removal of accumulated frozen/freezing rain can cost close to $10,000. Understanding conditions that lead to severe icing events is important and challenging. When an aircraft or rotorcraft flies in a cold climate, some of the super cooled droplets impinging on exposed aircraft surfaces may flow along the surface prior to freezing and give various forms and shapes of ice. The runback behavior of a water film on an aircraft affects the morphology of ice accretion and the rate of formation. In this study, we report the recent progress to develop an Ultrasonic Pulse-Echo (UPE) technique to provide real-time thickness distribution measurements of surface water flows driven by boundary layer airflows for aircraft icing studies. A series of initial experimental investigations are conducted in an ice wind tunnel employing an array of ultrasonic transducers placed underneath the surface of a flat plate. The water runback behavior on the plate is evaluated by measuring the thickness profile variation of the water film along the surface by using the UPE technique under various wind speed and flow rate conditions.

  4. NASA Now: Phase Change and Forces of Flight: Aircraft Icing Research

    NASA Video Gallery

    Tour the Icing Research Tunnel with Judith VanZante, aeromechanical engineer and icing specialist. VanZante explains the hazards of ice on aircraft, how it is formed, and why the research on ice pl...

  5. Experimental methodologies to support aircraft icing analysis

    NASA Technical Reports Server (NTRS)

    Hansman, R. John, Jr.; Kirby, Mark S.

    1987-01-01

    The experimental methodologies are illustrated by graphs, charts and line drawings. Typical ultrasonic echo signals for dry and wet ice growth, ice accretion rates for various tunnel configurations, the experimental configuration for flight tests of the ultrasonic measuring system and heat balance models used to predict ice growth are among the topics that are illustrated and briefly discussed.

  6. Aircraft measurements of microwave emission from Arctic Sea ice

    USGS Publications Warehouse

    Wilheit, T.; Nordberg, W.; Blinn, J.; Campbell, W.; Edgerton, A.

    1971-01-01

    Measurements of the microwave emission from Arctic Sea ice were made with aircraft at 8 wavelengths ranging from 0.510 to 2.81 cm. The expected contrast in emissivities between ice and water was observed at all wavelengths. Distributions of sea ice and open water were mapped from altitudes up to 11 km in the presence of dense cloud cover. Different forms of ice also exhibited strong contrasts in emissivity. Emissivity differences of up to 0.2 were observed between two types of ice at the 0.811-cm wavelength. The higher emissivity ice type is tentatively identified as having been formed more recently than the lower emissivity ice. ?? 1971.

  7. Light transport and general aviation aircraft icing research requirements

    NASA Technical Reports Server (NTRS)

    Breeze, R. K.; Clark, G. M.

    1981-01-01

    A short term and a long term icing research and technology program plan was drafted for NASA LeRC based on 33 separate research items. The specific items listed resulted from a comprehensive literature search, organized and assisted by a computer management file and an industry/Government agency survey. Assessment of the current facilities and icing technology was accomplished by presenting summaries of ice sensitive components and protection methods; and assessments of penalty evaluation, the experimental data base, ice accretion prediction methods, research facilities, new protection methods, ice protection requirements, and icing instrumentation. The intent of the research plan was to determine what icing research NASA LeRC must do or sponsor to ultimately provide for increased utilization and safety of light transport and general aviation aircraft.

  8. Studying Ice Formation from Aircraft: Experimental Constraints on Techniques for Sampling Ice and Ice Forming Particles

    NASA Astrophysics Data System (ADS)

    Stith, J. L.

    2015-12-01

    A major experimental pathway to study the role of ice forming particles in clouds involves evaporating ice particles in a counterflow virtual impactor (CVI), measuring the residue with airborne instrumentation to determine the IFP concentration, and then comparing these concentrations with simultaneous measurements of ice concentrations, as determined from various types of instruments designed to measure hydrometeor concentrations. In order for these types of experiments to provide meaningful results, they must consider a number of factors, such as the impact of the CVI on the ice particles and the effects of probe tip shattering on the measurement of ice concentrations. These problems can be minimized by careful selection of sampling conditions and by studying the morphology of the sampled ice particles.

  9. Progress toward the development of an aircraft icing analysis capability

    NASA Technical Reports Server (NTRS)

    Shaw, R. J.

    1984-01-01

    An overview of the NASA efforts to develop an aircraft icing analysis capability is presented. Discussions are included of the overall and long term objectives of the program as well as current capabilities and limitations of the various computer codes being developed. Descriptions are given of codes being developed to analyze two and three dimensional trajectories of water droplets, airfoil ice accretion, aerodynamic performance degradation of components and complete aircraft configurations, electrothermal deicer, and fluid freezing point depressant deicer. The need for bench mark and verification data to support the code development is also discussed.

  10. Precise Aircraft Guidance Techniques for NASA's Operation IceBridge

    NASA Astrophysics Data System (ADS)

    Sonntag, J. G.; Russell, R.

    2013-12-01

    We present a suite of novel aircraft guidance techniques we designed, developed and now operationally utilize to precisely guide large NASA aircraft and their sensor suites over polar science targets. Our techniques are based on real-time, non-differential Global Positioning System (GPS) data. They interact with the flight crew and the aircraft using a combination of yoke-mounted computer displays and an electronic interface to the aircraft's autopilot via the aircraft's Instrument Landing System (ILS). This ILS interface allows the crew to 'couple' the autopilot to our systems, which then guide the aircraft over science targets with considerably better accuracy than it can using its internal guidance. We regularly demonstrate errors in cross-track aircraft positioning of better than 4 m standard deviation and better than 2 m in mean offset over lengthy great-circle routes across the ice sheets. Our system also has a mode allowing for manual aircraft guidance down a predetermined path of arbitrary curvature, such as a sinuous glacier centerline. This mode is in general not as accurate as the coupled technique but is more versatile. We employ both techniques interchangeably and seamlessly during a typical Operation IceBridge science flight. Flight crews find the system sufficiently intuitive so that little or no familiarization is required prior to their accurately flying science lines. We regularly employ the system on NASA's P-3B and DC-8 aircraft, and since the interface to the aircraft's autopilot operates through the ILS, it should work well on any ILS-equipped aircraft. Finally, we recently extended the system to provide precise, three-dimensional landing approach guidance to the aircraft, thus transforming any approach into a precise ILS approach, even to a primitive runway. This was intended to provide a backup to the aircraft's internal landing systems in the event of a zero-visibility landing to a non-ILS equipped runway, such as the McMurdo sea ice runway

  11. Aircraft-Produced Ice Particles (APIPs): Additional Results and Further Insights.

    NASA Astrophysics Data System (ADS)

    Woodley, William L.; Gordon, Glenn; Henderson, Thomas J.; Vonnegut, Bernard; Rosenfeld, Daniel; Detwiler, Andrew

    2003-05-01

    This paper presents new results from studies of aircraft-produced ice particles (APIPs) in supercooled fog and clouds. Nine aircraft, including a Beech King Air 200T cloud physics aircraft, a Piper Aztec, a Cessna 421-C, two North American T-28s, an Aero Commander, a Piper Navajo, a Beech Turbo Baron, and a second four-bladed King Air were involved in the tests. The instrumented King Air served as the monitoring aircraft for trails of ice particles created, or not created, when the other aircraft were flown through clouds at various temperatures and served as both the test and monitoring aircraft when it itself was tested. In some cases sulfur hexafluoride (SF6) gas was released by the test aircraft during its test run and was detected by the King Air during its monitoring passes to confirm the location of the test aircraft wake. Ambient temperatures for the tests ranged between 5° and 12°C. The results confirm earlier published results and provide further insights into the APIPs phenomenon. The King Air at ambient temperatures less than 8°C can produce APIPs readily. The Piper Aztec and the Aero Commander also produced APIPs under the test conditions in which they were flown. The Cessna 421, Piper Navajo, and Beech Turbo Baron did not. The APIPs production potential of a T-28 is still indeterminate because a limited range of conditions was tested. Homogeneous nucleation in the adiabatically cooled regions where air is expanding around the rapidly rotating propeller tips is the cause of APIPs. An equation involving the propeller efficiency, engine thrust, and true airspeed of the aircraft is used along with the published thrust characteristics of the propellers to predict when the aircraft will produce APIPs. In most cases the predictions agree well with the field tests. Of all of the aircraft tested, the Piper Aztec, despite its small size and low horsepower, was predicted to be the most prolific producer of APIPs, and this was confirmed in field tests. The

  12. Effects of Ice Accretion on Aircraft Aerodynamics

    NASA Technical Reports Server (NTRS)

    Bragg, Michael B.

    1998-01-01

    The primary objective of this research was to support the development of a new ice accretion model by improving our physical understanding of the ice accretion process through experimental measurements. The focus was on the effect of the initial ice roughness (smooth/rough boundary) on the accretion process. This includes understanding the boundary-layer development over the roughness and especially its effect on the heat transfer which is fundamental to the ice accretion process. The research focused on acquiring the experimental data needed to formulate a new ice accretion physical model. Research was conducted to analyze boundary-layer data taken on a NACA 0012 airfoil with roughness to simulate the smooth/rough boundary. The effect of isolated roughness on boundary-layer transition was studied experimentally to determine if the classical critical roughness Reynolds number criteria could be applied to transition in the airfoil leading-edge area. The effect of simulated smooth/rough boundary roughness on convective heat transfer was studied to complete the study. During the course of this research the effect of free-stream wind tunnel turbulence on the boundary layer was measured. Since this quantity was not well known, research to accurately measure the wind tunnel turbulence in an icing cloud was undertaken. Preliminary results were attained and the final data were acquired, reduced and presented under a subsequent grant.

  13. Analysis of surface roughness generation in aircraft ice accretion

    NASA Technical Reports Server (NTRS)

    Hansman, R. J., Jr.; Reehorst, Andrew; Sims, James

    1992-01-01

    Patterns of roughness evolution have been studied analysis of high magnification video observations of accreting ice surfaces provided by the NASA Lewis Research Center. Three distinct patterns of surface roughness generation have been identified within the parametric regions studied. They include: Rime, Multi-Zone Glaze, and Uniform Glaze. Under most icing conditions, a brief period of transient rime ice growth was observed caused by heat conduction into the body. The resulting thin rime layer explains previously observed insensitivity of some ice accretions to substrate insensitivity of some ice accretions to substrate surface chemistry and may provide justification for simplifying assumptions in ice accretion sailing and modeling effects.

  14. Near-Real Time Cloud Properties and Aircraft Icing Indices from GEO and LEO Satellites

    NASA Technical Reports Server (NTRS)

    Minnis, Patrick; Smith, William L., Jr.; Nguyen, Louis; Spangenberg, D. A.; Heck, Patrick W.; Palikonda, Rabindra; Ayers, J. Kirk; Wolff, Cory; Murray, John J.

    2004-01-01

    Imagers on many of the current and future operational meteorological satellites in geostationary Earth orbit (GEO) and lower Earth orbit (LEO) have enough spectral channels to derive cloud microphysical properties useful for a variety of applications. The products include cloud amount, phase, optical depth, temperature, height and pressure, thickness, effective particle size, and ice or liquid water path, shortwave albedo, and outgoing longwave radiation for each imager pixel. Because aircraft icing depends on cloud temperature, droplet size, and liquid water content as well as aircraft variables, it is possible to estimate the potential icing conditions from the cloud phase, temperature, effective droplet size, and liquid water path. A prototype icing index is currently being derived over the contiguous USA in near-real time from Geostationary Operational Environmental Satellite (GOES-10 and 12) data on a half-hourly basis and from NOAA- 16 Advanced Very High Resolution (AVHRR) data when available. Because the threshold-based algorithm is sensitive to small errors and differences in satellite imager and icing is complex process, a new probability based icing diagnosis technique is developed from a limited set of pilot reports. The algorithm produces reasonable patterns of icing probability and intensities when compared with independent model and pilot report data. Methods are discussed for improving the technique for incorporation into operational icing products.

  15. Sea Ice Topography Profiling using Laser Altimetry from Small Unmanned Aircraft Systems

    NASA Astrophysics Data System (ADS)

    Crocker, Roger Ian

    Arctic sea ice is undergoing a dramatic transition from a perennial ice pack with a high prevalence of old multiyear ice, to a predominantly seasonal ice pack comprised primarily of young first-year and second-year ice. This transition has brought about changes in the sea ice thickness and topography characteristics, which will further affect the evolution and survivability of the ice pack. The varying ice conditions have substantial implications for commercial operations, international affairs, regional and global climate, our ability to model climate dynamics, and the livelihood of Arctic inhabitants. A number of satellite and airborne missions are dedicated to monitoring sea ice, but they are limited by their spatial and temporal resolution and coverage. Given the fast rate of sea ice change and its pervasive implications, enhanced observational capabilities are needed to augment the current strategies. The CU Laser Profilometer and Imaging System (CULPIS) is designed specifically for collecting fine-resolution elevation data and imagery from small unmanned aircraft systems (UAS), and has a great potential to compliment ongoing missions. This altimeter system has been integrated into four different UAS, and has been deployed during Arctic and Antarctic science campaigns. The CULPIS elevation measurement accuracy is shown to be 95±25 cm, and is limited primarily by GPS positioning error (<25 cm), aircraft attitude determination error (<20 cm), and sensor misalignment error (<20 cm). The relative error is considerably smaller over short flight distances, and the measurement precision is shown to be <10 cm over a distance of 200 m. Given its fine precision, the CULPIS is well suited for measuring sea ice topography, and observed ridge height and ridge separation distributions are found to agree with theoretical distributions to within 5%. Simulations demonstrate the inability of course-resolution measurements to accurately represent the theoretical distributions

  16. Analytical ice shape predictions for flight in natural icing conditions

    NASA Technical Reports Server (NTRS)

    Berkowitz, Brian M.; Riley, James T.

    1988-01-01

    LEWICE is an analytical ice prediction code that has been evaluated against icing tunnel data, but on a more limited basis against flight data. Ice shapes predicted by LEWICE is compared with experimental ice shapes accreted on the NASA Lewis Icing Research Aircraft. The flight data selected for comparison includes liquid water content recorded using a hot wire device and droplet distribution data from a laser spectrometer; the ice shape is recorded using stereo photography. The main findings are as follows: (1) An equivalent sand grain roughness correlation different from that used for LEWICE tunnel comparisons must be employed to obtain satisfactory results for flight; (2) Using this correlation and making no other changes in the code, the comparisons to ice shapes accreted in flight are in general as good as the comparisons to ice shapes accreted in the tunnel (as in the case of tunnel ice shapes, agreement is least reliable for large glaze ice shapes at high angles of attack); (3) In some cases comparisons can be somewhat improved by utilizing the code so as to take account of the variation of parameters such as liquid water content, which may vary significantly in flight.

  17. Project ADIOS: Aircraft Deployable Ice Observation System

    NASA Astrophysics Data System (ADS)

    Gudmundsson, G. H.

    2013-12-01

    Regions of the Antarctic that are of scientific interest are often too heavily crevassed to enable a plane to land, or permit safe access from a field camp. We have developed an alternative strategy for instrumenting these regions: a sensor that can be dropped from an overflying aircraft. Existing aircraft deployable sensors are not suitable for long term operations in areas where snow accumulates, as they are quickly buried. We have overcome this problem by shaping the sensor like an aerodynamic mast with fins and a small parachute. After being released from the aircraft, the sensor accelerates to 42m/s and stabilizes during a 10s descent. On impact with the snow surface the sensor package buries itself to a depth of 1m then uses the large surface area of the fins to stop it burying further. This leaves a 1.5m mast protruding high above the snow surface to ensure a long operating life. The high impact kinetic energy and robust fin braking mechanism ensure that the design works in both soft and hard snow. Over the past two years we have developed and tested our design with a series of aircraft and wind tunnel tests. Last season we used this deployment strategy to successfully install a network of 31 single band GPS sensors in regions where crevassing has previously prevented science operations: Pine Island Glacier, West Antarctica, and Scar Inlet, Antarctic Peninsula. This season we intend to expand on this network by deploying a further 25 single and dual band GPS sensors on Thwaites Glacier, West Antarctica.

  18. Ice Accretion Formations on a NACA 0012 Swept Wing Tip in Natural Icing Conditions

    NASA Technical Reports Server (NTRS)

    Vargas, Mario; Giriunas, Julius A.; Ratvasky, Thomas P.

    2002-01-01

    An experiment was conducted in the DeHavilland DHC-6 Twin Otter Icing Research Aircraft at NASA Glenn Research Center to study the formation of ice accretions on swept wings in natural icing conditions. The experiment was designed to obtain ice accretion data to help determine if the mechanisms of ice accretion formation observed in the Icing Research Tunnel are present in natural icing conditions. The experiment in the Twin Otter was conducted using a NACA 0012 swept wing tip. The model enabled data acquisition at 0 deg, 15 deg, 25 deg, 30 deg, and 45 deg sweep angles. Casting data, ice shape tracings, and close-up photographic data were obtained. The results showed that the mechanisms of ice accretion formation observed in-flight agree well with the ones observed in the Icing Research Tunnel. Observations on the end cap of the airfoil showed the same strong effect of the local sweep angle on the formation of scallops as observed in the tunnel.

  19. Numerical modeling of runback water on ice protected aircraft surfaces

    NASA Technical Reports Server (NTRS)

    Al-Khalil, Kamel M.; Keith, Theo G., Jr.; Dewitt, Kenneth J.

    1992-01-01

    A numerical simulation for 'running wet' aircraft anti-icing systems is developed. The model includes breakup of the water film, which exists in regions of direct impingement, into individual rivulets. The wetness factor distribution resulting from the film breakup and the rivulet configuration on the surface are predicted in the numerical solution procedure. The solid wall is modeled as a multilayer structure and the anti-icing system used is of the thermal type utilizing hot air and/or electrical heating elements embedded with the layers. Details of the calculation procedure and the methods used are presented.

  20. Sea Ice and Oceanographic Conditions.

    ERIC Educational Resources Information Center

    Oceanus, 1986

    1986-01-01

    The coastal waters of the Beaufort Sea are covered with ice three-fourths of the year. These waters (during winter) are discussed by considering: consolidation of coastal ice; under-ice water; brine circulation; biological energy; life under the ice (including kelp and larger animals); food chains; and ice break-up. (JN)

  1. Remote sensing as a research tool. [sea ice surveillance from aircraft and spacecraft

    NASA Technical Reports Server (NTRS)

    Carsey, F. D.; Zwally, H. J.

    1986-01-01

    The application of aircraft and spacecraft remote sensing techniques to sea ice surveillance is evaluated. The effects of ice in the air-sea-ice system are examined. The measurement principles and characteristics of remote sensing methods for aircraft and spacecraft surveillance of sea ice are described. Consideration is given to ambient visible light, IR, passive microwave, active microwave, and laser altimeter and sonar systems. The applications of these systems to sea ice surveillance are discussed and examples are provided. Particular attention is placed on the use of microwave data and the relation between ice thickness and sea ice interactions. It is noted that spacecraft and aircraft sensing techniques can successfully measure snow cover; ice thickness; ice type; ice concentration; ice velocity field; ocean temperature; surface wind vector field; and air, snow, and ice surface temperatures.

  2. Lewis icing research tunnel test of the aerodynamic effects of aircraft ground deicing/anti-icing fluids

    NASA Technical Reports Server (NTRS)

    Runyan, L. James; Zierten, Thomas A.; Hill, Eugene G.; Addy, Harold E., Jr.

    1992-01-01

    A wind tunnel investigation of the effect of aircraft ground deicing/anti-icing fluids on the aerodynamic characteristics of a Boeing 737-200ADV airplane was conducted. The test was carried out in the NASA Lewis Icing Research Tunnel. Fluids tested include a Newtonian deicing fluid, three non-Newtonian anti-icing fluids commercially available during or before 1988, and eight new experimental non-Newtonian fluids developed by four fluid manufacturers. The results show that fluids remain on the wind after liftoff and cause a measurable lift loss and drag increase. These effects are dependent on the high-lift configuration and on the temperature. For a configuration with a high-lift leading-edge device, the fluid effect is largest at the maximum lift condition. The fluid aerodynamic effects are related to the magnitude of the fluid surface roughness, particularly in the first 30 percent chord. The experimental fluids show a significant reduction in aerodynamic effects.

  3. Flying Qualities Evaluation of a Commuter Aircraft With an Ice Contaminated Tailplane

    NASA Technical Reports Server (NTRS)

    Ranaudo, Richard J.; Ratvasky, Thomas P.; FossVanZante, Judith

    2000-01-01

    During the NASA/FAA (Federal Aviation Administration) Tailplane Icing Program, pilot evaluations of aircraft flying qualities were conducted with various ice shapes attached to the horizontal tailplane of the NASA Twin Otter Icing Research Aircraft. Initially, only NASA pilots conducted these evaluations, assessing the differences in longitudinal flight characteristics between the baseline or clean aircraft, and the aircraft configured with an Ice Contaminated Tailplane (ICT). Longitudinal tests included Constant Airspeed Flap Transitions, Constant Airspeed Thrust Transitions, zero-G Pushovers, Repeat Elevator Doublets, and Simulated Approach and Go-Around tasks. Later in the program, guest pilots from government and industry were invited to fly the NASA Twin Otter configured with a single full-span artificial ice shape attached to the leading edge of the horizontal tailplane. This shape represented ice formed due to a 'Failed Boot' condition, and was generated from tests in the Glenn Icing Research Tunnel on a full-scale tailplane model. Guest pilots performed longitudinal handling tests, similar to those conducted by the NASA pilots, to evaluate the ICT condition. In general, all pilots agreed that longitudinal flying qualities were degraded as flaps were lowered, and further degraded at high thrust settings. Repeat elevator doublets demonstrated reduced pitch damping effects due to ICT, which is a characteristic that results in degraded flying qualities. Pilots identified elevator control force reversals (CFR) in zero-G pushovers at a 20 deg flap setting, a characteristic that fails the FAR 25 no CFR certification requirement. However, when the same pilots used the Cooper-Harper rating scale to perform a simulated approach and go-around task at the 20 deg flap setting, they rated the airplane as having Level I and Level II flying qualities respectively. By comparison, the same task conducted at the 30 deg flap setting, resulted in Level II flying qualities for

  4. Effective Training for Flight in Icing Conditions

    NASA Technical Reports Server (NTRS)

    Barnhart, Billy P.; Ratvasky, Thomas P.

    2007-01-01

    The development of a piloted flight simulator called the Ice Contamination Effects Flight Training Device (ICEFTD) was recently completed. This device demonstrates the ability to accurately represent an iced airplane s flight characteristics and is utilized to train pilots in recognizing and recovering from aircraft handling anomalies that result from airframe ice formations. The ICEFTD was demonstrated at three recent short courses hosted by the University of Tennessee Space Institute. It was also demonstrated to a group of pilots at the National Test Pilot School. In total, eighty-four pilots and flight test engineers from industry and the regulatory community spent approximately one hour each in the ICEFTD to get a "hands on" lesson of an iced airplane s reduced performance and handling qualities. Additionally, pilot cues of impending upsets and recovery techniques were demonstrated. The purpose of this training was to help pilots understand how ice contamination affects aircraft handling so they may apply that knowledge to the operations of other aircraft undergoing testing and development. Participant feedback on the ICEFTD was very positive. Pilots stated that the simulation was very valuable, applicable to their occupations, and provided a safe way to explore the flight envelope. Feedback collected at each demonstration was also helpful to define additional improvements to the ICEFTD; many of which were then implemented in subsequent demonstrations.

  5. Detection and Analysis of High Ice Concentration Events and Supercooled Drizzle from IAGOS Commercial Aircraft

    NASA Astrophysics Data System (ADS)

    Gallagher, Martin; Baumgardner, Darrel; Lloyd, Gary; Beswick, Karl; Freer, Matt; Durant, Adam

    2016-04-01

    Hazardous encounters with high ice concentrations that lead to temperature and airspeed sensor measurement errors, as well as engine rollback and flameout, continue to pose serious problems for flight operations of commercial air carriers. Supercooled liquid droplets (SLD) are an additional hazard, especially for smaller commuter aircraft that do not have sufficient power to fly out of heavy icing conditions or heat to remove the ice. New regulations issued by the United States and European regulatory agencies are being implemented that will require aircraft below a certain weight class to carry sensors that will detect and warn of these types of icing conditions. Commercial aircraft do not currently carry standard sensors to detect the presence of ice crystals in high concentrations because they are typical found in sizes that are below the detection range of aircraft weather radar. Likewise, the sensors that are currently used to detect supercooled water do not respond well to drizzle-sized drops. Hence, there is a need for a sensor that can fill this measurement void. In addition, the forecast models that are used to predict regions of icing rely on pilot observations as the only means to validate the model products and currently there are no forecasts for the prevalence of high altitude ice crystals. Backscatter Cloud Probes (BCP) have been flying since 2011 under the IAGOS project on six Airbus commercial airliners operated by Lufthansa, Air France, China Air, Iberia and Cathay Pacific, and measure cloud droplets, ice crystals and aerosol particles larger than 5 μm. The BCP can detect these particles and measures an optical equivalent diameter (OED) but is not able to distinguish the type of particle, i.e. whether they are droplets, ice crystals, dust or ash. However, some qualification can be done based on measured temperature to discriminate between liquid water and ice. The next generation BCP (BCPD, Backscatter Cloud Probe with polarization detection) is

  6. Stress-strain state of ice cover during aircraft takeoff and landing

    NASA Astrophysics Data System (ADS)

    Pogorelova, A. V.; Kozin, V. M.; Matyushina, A. A.

    2015-09-01

    We consider the linear unsteady motion of an IL-76TD aircraft on ice. Water is treated as an ideal incompressible liquid, and the liquid motion is considered potential. Ice cover is modeled by an initially unstressed uniform isotropic elastic plate, and the load exerted by the aircraft on the ice cover with consideration of the wing lift is modeled by regions of distributed pressure of variable intensity, arranged under the aircraft landing gear. The effect of the thickness and elastic modulus of the ice plate, takeoff and landing regimes on stress-strain state of the ice cover used as a runway.

  7. Satellite and aircraft passive microwave observations during the Marginal Ice Zone Experiment in 1984

    NASA Astrophysics Data System (ADS)

    Gloersen, Per; Campbell, William J.

    1988-06-01

    During the Marginal Ice Zone Experiment in the Fram Strait in June-July 1984, a number of aircraft with microwave sensors and the scanning multichannel microwave radiometer (SMMR) on board the Nimbus 7 satellite were used to acquire large-scale and mesoscale ice-ocean observations in conjunction with local surface measurements made by experimenters based on helicopter-equipped ice-strengthened vessels. An analysis of the data acquired during six flights of one such aircraft, the NASA CV-990 airborne laboratory, is discussed in this paper. Included in the instrument complement of the CV-990 were two passive microwave imagers operating at wavelengths of 0.33 and 1.55 cm and the airborne multichannel microwave radiometer (AMMR) operating at wavelengths of 0.81, 1.4, and 1.7 cm for both horizontal and vertical polarizations. Total and multiyear sea ice concentrations calculated from the AMMR data were found to agree with similar calculations using SMMR data. This is the first check of the performance of the SMMR Team ice algorithm for near-melting point conditions. The temperature dependence of the multiyear sea ice concentration determination near the melting point was found to be the same for both airborne and spacecraft instrument data and to be correlated with presence or absence of clouds. Finally, it was found that a spectral gradient ratio using the data from both the 0.33- and 1.55-cm radiometers provides more reliable distinctions between low total ice concentrations and open water storm effects near the ice edge than does either singly.

  8. Real-Time Cloud, Radiation, and Aircraft Icing Parameters from GOES over the USA

    NASA Technical Reports Server (NTRS)

    Minnis, Patrick; Nguyen, Louis; Smith, William, Jr.; Young, David; Khaiyer, Mandana; Palikonda, Rabindra; Spangenberg, Douglas; Doelling, Dave; Phan, Dung; Nowicki, Greg

    2004-01-01

    A preliminary new, physically based method for realtime estimation of the probability of icing conditions has been demonstrated using merged GOES-10 and 12 data over the continental United States and southern Canada. The algorithm produces pixel-level cloud and radiation properties as well as an estimate of icing probability with an associated intensity rating Because icing depends on so many different variables, such as aircraft size or air speed, it is not possible to achieve 100% success with this or any other type of approach. This initial algorithm, however, shows great promise for diagnosing aircraft icing and putting it at the correct altitude within 0.5 km most of the time. Much additional research must be completed before it can serve as a reliable input for the operational CIP. The delineation of the icing layer vertical boundaries will need to be improved using either the RUC or balloon soundings or ceilometer data to adjust the cloud base height, a change that would require adjustment of the cloud-top altitude also.

  9. The effect of ice crystal shape on aircraft contrails

    NASA Astrophysics Data System (ADS)

    Meza Castillo, Omar E.

    Aircraft contrails are a common phenomenon observed in the sky. They are formed mainly of water, from the ambient atmosphere and as a by-product of the combustion process, in the form of ice crystals. They have been identified as a potential contributor to global warming. Some contrails can be long-lived and create man-made cloud cover, thus possibly altering the radiative balance of the earth. There has been a great deal of research on various aspects of contrail development, but to date, little has been done on the influence of ice crystal shapes on the contrail evolution. In-situ studies have reported that young contrails are mainly quasi-spherical crystals while older contrails can have a much more diverse spectrum of possible shapes. The most common shapes found in contrails are quasi-spherical, hexagonal columns, hexagonal plates, and bullet rosettes. Numerical simulations of contrails to date typically have assumed "spherical" as the default ice shape. This work simulated contrail development with a large eddy simulation (LES) model that implemented both spherical and non-spherical shapes to examine the effects. The included shape effect parameters, such as capacitance coefficient, ventilation factor, Kelvin effect, fall velocity and ice crystal surface area, help to establish the shape difference in the results. This study also investigated initial sensitivities to an additional ice parameter, the ice deposition coefficient. The literature shows conflicting values for this coefficient over a wide range. In the course of this investigation a comparison of various ice metrics was made for simulations with different assumed crystal shapes (spheres, hexagonal columns, hexagonal plates, bullet rosettes and combination of shapes). The simulations were performed at early and late contrail time, with a range of ice crystal sizes, and with/without coupled radiation. In young and older contrails and without coupled radiation, the difference from the shape effect in

  10. Towards GPS Surface Reflection Remote Sensing of Sea Ice Conditions

    NASA Technical Reports Server (NTRS)

    Komjathy, A.; Maslanik, J. A.; Zavorotny, V. U.; Axelrad, P.; Katzberg, S. J.

    2000-01-01

    This paper describes the research to extend the application of Global Positioning System (GPS) signal reflections, received by airborne instruments, to cryospheric remote sensing. The characteristics of the GPS signals and equipment afford the possibility of new measurements not possible with existing radar and passive microwave systems. In particular, the GPS receiving systems are small and light-weight, and as such are particularly well suited to be deployed on small aircraft or satellite platforms with minimal impact. Our preliminary models and experimental results indicate that reflected GPS signals have potential to provide information on the presence and condition of sea and fresh-water ice as well as the freeze/thaw state of frozen ground. In this paper we show results from aircraft experiments over the ice pack near Barrow, Alaska suggesting correlation between forward scattered GPS returns and RADARSAT backscattered signals.

  11. 'Scaling' analysis of the ice accretion process on aircraft surfaces

    NASA Technical Reports Server (NTRS)

    Keshock, E. G.; Tabrizi, A. H.; Missimer, J. R.

    1982-01-01

    A comprehensive set of scaling parameters is developed for the ice accretion process by analyzing the energy equations of the dynamic freezing zone and the already frozen ice layer, the continuity equation associated with supercooled liquid droplets entering into and impacting within the dynamic freezing zone, and energy equation of the ice layer. No initial arbitrary judgments are made regarding the relative magnitudes of each of the terms. The method of intrinsic reference variables in employed in order to develop the appropriate scaling parameters and their relative significance in rime icing conditions in an orderly process, rather than utilizing empiricism. The significance of these parameters is examined and the parameters are combined with scaling criteria related to droplet trajectory similitude.

  12. Statistical Study of Aircraft Icing Probabilities at the 700- and 500- Millibar Levels over Ocean Areas in the Northern Hemisphere

    NASA Technical Reports Server (NTRS)

    Perkins, Porter J.; Lewis, William; Mulholland, Donald R.

    1957-01-01

    A statistical study is made of icing data reported from weather reconnaissance aircraft flown by Air Weather Service (USAF). The weather missions studied were flown at fixed flight levels of 500 millibars (18,000 ft) and 700 millibars (10,000 ft) over wide areas of the Pacific, Atlantic, and Arctic Oceans. This report is presented as part of a program conducted by the NACA to obtain extensive icing statistics relevant to aircraft design and operation. The thousands of in-flight observations recorded over a 2- to 4-year period provide reliable statistics on icing encounters for the specific areas, altitudes, and seasons included in the data. The relative frequencies of icing occurrence are presented, together with the estimated icing probabilities and the relation of these probabilities to the frequencies of flight in clouds and cloud temperatures. The results show that aircraft operators can expect icing probabilities to vary widely throughout the year from near zero in the cold Arctic areas in winter up to 7 percent in areas where greater cloudiness and warmer temperatures prevail. The data also reveal a general tendency of colder cloud temperatures to reduce the probability of icing in equally cloudy conditions.

  13. Smart skin technology development for measuring ice accretion, stall, and high AOA aircraft performance. Part 1: Capacitive ice detector development

    NASA Technical Reports Server (NTRS)

    Pruzan, Daniel A.; Khatkhate, Ateen A.; Gerardi, Joseph J.; Hickman, Gail A.

    1993-01-01

    A reliable way to detect and measure ice accretion during flight is required to reduce the hazards of icing currently threatening present day aircraft. Many of the sensors used for this purpose are invasive (probe) sensors which must be placed in areas of the airframe where ice does not naturally form. Due to the difference in capture efficiency of the exposed surface, difficulties result in correlating the ice accretion on the probe to what is happening on a number of vastly different airfoil sections. Most flush mounted sensors in use must be integrated into the aircraft surface by cutting or drilling the aircraft surface. An alternate type of ice detector which is based on a NASA patent is currently being investigated at Innovative Dynamics, Inc. (IDI). Results of the investigation into the performance of different capacitive type sensor designs, both rigid as well as elastic, are presented.

  14. Close-up analysis of aircraft ice accretion

    NASA Technical Reports Server (NTRS)

    Hansman, R. John; Breuer, Kenneth S.; Hazan, Didier; Reehorst, Andrew; Vargas, Mario

    1993-01-01

    Various types of ice formation have been studied by analysis of high magnification video observations. All testing was conducted in the NASA Lewis Icing Research Tunnel (IRT). A faired 8.9 cm (3.5 in.) diameter metal-clad cylinder and a 5.1 (2 in.) aluminum cylinder were observed by close-up and overview video cameras for several wind tunnel conditions. These included close-up grazing angle, close-up side view, as well as overhead and side overview cameras. Still photographs were taken at the end of each spray along with tracings of the subsequent ice shape. While in earlier tests only the stagnation region was observed, the entire area from the stagnation line to the horn region of glaze ice shapes was observed in this test. The modes or horn formation have been identified within the range of conditions observed. In the horn region, Horn Type A ice is formed by 'dry' feather growth into the flow direction and Horn Type B is formed by a 'wet' growth normal to the surface. The feather growth occurs when the freezing fraction is near unity and roughness elements exist to provide an initial growth site.

  15. Detection of the Impact of Ice Crystal Accretion in an Aircraft Engine Compression System During Dynamic Operation

    NASA Technical Reports Server (NTRS)

    May, Ryan D.; Simon, Donald L.; Guo, Ten-Huei

    2014-01-01

    The accretion of ice in the compression system of commercial gas turbine engines operating in high ice water content conditions is a safety issue being studied by the aviation community. While most of the research focuses on the underlying physics of ice accretion and the meteorological conditions in which accretion can occur, a systems-level perspective on the topic lends itself to potential near-term operational improvements. Here a detection algorithm is developed which has the capability to detect the impact of ice accretion in the Low Pressure Compressor of an aircraft engine during steady flight as well as during changes in altitude. Unfortunately, the algorithm as implemented was not able to distinguish throttle changes from ice accretion and thus more work remains to be done.

  16. Influence of color coatings on aircraft surface ice detection based on multi-wavelength imaging

    NASA Astrophysics Data System (ADS)

    Zhuge, Jing-chang; Yu, Zhi-jing; Gao, Jian-shu; Zheng, Da-chuan

    2016-03-01

    In this paper, a simple aircraft surface ice detection system is proposed based on multi-wavelength imaging. Its feasibility is proved by the experimental results. The influence of color coatings of aircraft surface is investigated. The results show that the ice area can be clearly distinguished from the red, white, gray and blue coatings painted aluminum plates. Due to the strong absorption, not enough signals can be detected for the black coatings. Thus, a deep research is needed. Even though, the results of this paper are helpful to the development of aircraft surface ice detection.

  17. Methods for Scaling Icing Test Conditions

    NASA Technical Reports Server (NTRS)

    Anderson, David N.

    1995-01-01

    This report presents the results of tests at NASA Lewis to evaluate several methods to establish suitable alternative test conditions when the test facility limits the model size or operating conditions. The first method was proposed by Olsen. It can be applied when full-size models are tested and all the desired test conditions except liquid-water content can be obtained in the facility. The other two methods discussed are: a modification of the French scaling law and the AEDC scaling method. Icing tests were made with cylinders at both reference and scaled conditions representing mixed and glaze ice in the NASA Lewis Icing Research Tunnel. Reference and scale ice shapes were compared to evaluate each method. The Olsen method was tested with liquid-water content varying from 1.3 to .8 g/m(exp3). Over this range, ice shapes produced using the Olsen method were unchanged. The modified French and AEDC methods produced scaled ice shapes which approximated the reference shapes when model size was reduced to half the reference size for the glaze-ice cases tested.

  18. EOS Aqua AMSR-E Arctic Sea Ice Validation Program: Arctic2003 Aircraft Campaign Flight Report

    NASA Technical Reports Server (NTRS)

    Cavalieri, D. J.; Markus,T.

    2003-01-01

    In March 2003 a coordinated Arctic sea ice validation field campaign using the NASA Wallops P-3B aircraft was successfully completed. This campaign was part of the program for validating the Earth Observing System (EOS) Aqua Advanced Microwave Scanning Radiometer (AMSR-E) sea ice products. The AMSR-E, designed and built by the Japanese National Space Development Agency for NASA, was launched May 4, 2002 on the EOS Aqua spacecraft. The AMSR-E sea ice products to be validated include sea ice concentration, sea ice temperature, and snow depth on sea ice. This flight report describes the suite of instruments flown on the P-3, the objectives of each of the seven flights, the Arctic regions overflown, and the coordination among satellite, aircraft, and surface-based measurements. Two of the seven aircraft flights were coordinated with scientists making surface measurements of snow and ice properties including sea ice temperature and snow depth on sea ice at a study area near Barrow, AK and at a Navy ice camp located in the Beaufort Sea. Two additional flights were dedicated to making heat and moisture flux measurements over the St. Lawrence Island polynya to support ongoing air-sea-ice processes studies of Arctic coastal polynyas. The remaining flights covered portions of the Bering Sea ice edge, the Chukchi Sea, and Norton Sound.

  19. Icing Frequencies Experienced During Climb and Descent by Fighter-Interceptor Aircraft

    NASA Technical Reports Server (NTRS)

    Perkins, Porter J.

    1958-01-01

    Data and analyses are presented on the relative frequencies of occurrence and severity of icing cloud layers encountered by jet aircraft in the climb and descent phases of flights to high altitudes. Fighter-interceptor aircraft operated by the Air Defense Command (USAF) at bases in the Duluth and Seattle areas collected the data with icing meters installed for a l-year period. The project was part of an extensive program conducted by the NACA to collect Icing cloud data for evaluating the icing problem relevant to routine operations. The average frequency of occurrence of icing was found to be about 5 percent of the number of climbs and descents during 1 year of operations The icing encounters were predominantly in the low and middle cloud layers, decreasing above 15,000 feet to practically none above 25,000 feet. The greatest thickness of ice that would accumulate on any aircraft component (as indicated by the accretion on a small object) was measured with the icing meters. The ice thicknesses on a small sensing probe averaged less than 1/32 inch and did not exceed 1/2 inch. Such accumulations are relatively small when compared with those that can form during horizontal flight in icing clouds. The light accretions resulted from relatively steep angles of flight through generally thin cloud layers. Because of the limited statistical reliability of the results, an analysis was made using previous statistics on icing clouds below an altitude of 20,000 feet to determine the general icing severity probabilities. The calculations were made using adiabatic lifting as a basis to establish the liquid-water content. Probabilities of over-all ice accretions on a small object as a function of airspeed and rate of climb were computed from the derived water contents. These results were then combined with the probability of occurrence of icing in order to give the icing severity that can be expected for routine aircraft operations.

  20. Use of Unmanned Aircraft Systems in Observations of Glaciers, Ice Sheets, Sea Ice and Snow Fields

    NASA Astrophysics Data System (ADS)

    Herzfeld Mayer, M. U.

    2015-12-01

    Unmanned Aircraft Systems (UAS) are being used increasingly in observations of the Earth, especially as such UAS become smaller, lighter and hence less expensive. In this paper, we present examples of observations of snow fields, glaciers and ice sheets and of sea ice in the Arctic that have been collected from UAS. We further examine possibilities for instrument miniaturization, using smaller UAS and smaller sensors for collecting data. The quality and type of data is compared to that of satellite observations, observations from manned aircraft and to measurements made during field experiments on the ground. For example, a small UAS can be sent out to observe a sudden event, such as a natural catastrophe, and provide high-resolution imagery, but a satellite has the advantage of providing the same type of data over much of the Earth's surface and for several years, but the data is generally of lower resolution. Data collected on the ground typically have the best control and quality, but the survey area is usually small. Here we compare micro-topographic measurements made on snow fields the Colorado Rocky Mountains with airborne and satellite data.

  1. Wind turbine performance under icing conditions

    SciTech Connect

    Jasinski, W.J.; Noe, S.C.; Selig, M.S.; Bragg, M.B.

    1998-02-01

    The effects of rime ice on horizontal axis wind turbine performance were estimated. For typical supercooled fog conditions found in cold northern regions, four rime ice accretions on the S809 wind turbine airfoil were predicted using the NASA LEWICE code. The resulting airfoil/ice profile combinations were wind tunnel tested to obtain the lift, drag, and pitching moment characteristics over the Reynolds number range 1--2 {times} 10{sup 6}. These data were used in the PROPID wind turbine performance prediction code to predict the effects of rime ice on a 450-kW rated-power, 28.7-m diameter turbine operated under both stall-regulated and variable-speed/variable-pitch modes. Performance losses on the order of 20% were observed for the variable-speed/variable-pitch rotor. For the stall-regulated rotor, however, a relatively small rime ice profile yielded significantly larger performance losses. For a larger 0.08c-long rime ice protrusion, however, the rated peak power was exceeded by 16% because at high angles the rime ice shape acted like a leading edge flap, thereby increasing the airfoil C{sub l,max} and delaying stall.

  2. Analysis of Microphysics Mechanisms in Icing Aircraft Events: A Case Study

    NASA Astrophysics Data System (ADS)

    Sanchez, Jose Luis; Fernández, Sergio; Gascón, Estibaliz; Weigand, Roberto; Hermida, Lucia; Lopez, Laura; García-Ortega, Eduardo

    2013-04-01

    The appearance of Supercooled Large Drops (SLD) can give way to icing aircraft. In these cases, atmospheric icing causes an unusual loss of support on the aircraft due to the rapid accumulation of ice on the wings or measurement instruments. There are two possible ways that SLD can be formed: The first is through a process called "warm nose", followed by "resupercooling". This process is usually associated with the entrance of warm fronts. The second possibility is that drops are formed by the process of condensation, and they grow, to sizes of at least 50 µm through processes of collision-coalescence, in environments with temperatures inferior to 0°C at all times, but without being able to produce a freezing process. Some authors point out that approximately 75% of gelling precipitation events are produced as a consequence of this second situation. Within the framework of the TECOAGUA Project, a series of scientific flights were performed in order to collect data in cloud systems capable of producing precipitation during the winter period and their capacity to create environments favorable to "icing aircraft". These flights were carried out making use of a C 212-200 aircraft, belonging to the National Institute of Aerospatial Techniques (INTA), with a CAPS installed. On 1 February 2012, the C 212-200 aircraft took off from the airport in Torrejón de Ardoz (Madrid), flying about 70 km to stand upright on the northern side of the Central System, finding itself at a flight level of 3500 m, an elevated concentration of SLD at temperatures around -12°C, with liquid water content up to 0.44 g/m3, which provoked the accumulation of ice on the outline of the aircraft's wings, which required a cancellation of the flight. Surrounding the flight area, a microwave radiometer (MWR) was installed. An area of instability between 750 hPa and 600 hPa was identified in the vertical MWR profiles of temperature and humidity during the hour of the flight. It is mainly in this

  3. Alternative aircraft anti-icing formulations with reduced aquatic toxicity and biochemical oxygen demand

    USGS Publications Warehouse

    Gold, Harris; Joback, Kevin; Geis, Steven; Bowman, George; Mericas, Dean; Corsi, Steven R.; Ferguson, Lee

    2010-01-01

    The current research was conducted to identify alternative aircraft and pavement deicer and anti-icer formulations with improved environmental characteristics compared to currently used commercial products (2007). The environmental characteristics of primary concern are the biochemical oxygen demand (BOD) and aquatic toxicity of the fully formulated products. Except when the distinction among products is necessary for clarity, “deicer” will refer to aircraft-deicing fluids (ADFs), aircraft anti-icing fluids (AAFs), and pavementdeicing materials (PDMs).

  4. In-situ aircraft observations of ice supersaturation and cirrus clouds in global field studies

    NASA Astrophysics Data System (ADS)

    Diao, M.; Zondlo, M. A.

    2012-12-01

    Clouds play important roles in the Earth's climate and weather system, and the net forcing of all clouds results in a cooling effect on the Earth's surface. However, clouds remain one of the largest uncertainties in climate models. The IPCC AR4 report shows that both the magnitude and sign of the changes in cloud radiative forcing in response to anthropogenic aerosols are highly uncertain. Cirrus clouds are a type of ice clouds that occur at 235-185K with a net warming effect on the Earth surface. Cirrus cloud formation requires ice supersaturation (ISS), i.e., relative humidity with respect to ice (RHi) greater than 100%. Because ISS is critically related to the ice nucleation processes, it is also an indicator of any changes of ice nucleation and cirrus cloud formation. Here we use the in-situ 1 Hz aircraft observations by the Vertical Cavity Surface Emitting Laser (VCSEL) hygrometer on board the NSF Gulfstream-V research aircraft to analyze the differences of ISS distribution between the Northern and Southern Hemispheres (NH and SH). Our dataset is based on five deployments of the NSF Hiaper Pole-to-Pole Observations (HIPPO) Global field campaigns, including nine Pole-to-Pole transects from the year of 2009 to 2011, extending from 87°N to 67°S, covering four seasons, and the Stratosphere-Troposphere Analyses of Regional Transport (START08) campaign over North America region in April-June 2008. The flight track was mostly over the mid-Pacific Ocean, and also parts of the North America and Australia. We found that the frequency of ISS is much higher in NH than SH for the clear-sky conditions, while the in-cloud conditions show no significant difference between the two hemispheres. Our conclusion is in sharp contrast to the previous aircraft observations which concluded that the SH has higher frequency of ISS for clear-sky conditions based on two flight campaigns at Prestwick, Scotland (55°N) and Punta Arenas, Chile (55°S). We propose a method to separate

  5. Concurrent remote sensing of Arctic sea ice from submarine and aircraft

    NASA Technical Reports Server (NTRS)

    Wadhams, P.; Davis, N. R.; Comiso, J. C.; Kutz, R.; Crawford, J.; Jackson, G.; Krabill, W.; Sear, C. B.; Swift, R.; Tucker, W. B., III

    1991-01-01

    In May 1987 a concurrent remote sensing study of Arctic sea ice from above and below was carried out. A submarine equipped with sidescan and upward looking sonar collaborated with two remote sensing aircraft equipped with passive microwave, synthetic aperture radar (SAR), a laser profilometer and an infrared radiometer. By careful registration of the three tracks it has been possible to find relationships between ice type, ice morphology and thickness, SAR backscatter and microwave brightness temperatures. The key to the process has been the sidescan sonar's ability to identify ice type through differences in characteristic topography. Over a heavily ridged area of mainly multiyear ice there is a strong positive correlation between SAR backscatter and ice draft or elevation. It was also found that passive and active microwave complement each other in that SAR has a high contrast between open water and multiyear ice, while passive microwave has a high contrast between open water and first-year ice.

  6. In-situ aircraft observations of ice concentrations within clouds over the Antarctic Peninsula and Larsen Ice Shelf

    NASA Astrophysics Data System (ADS)

    Grosvenor, D. P.; Choularton, T. W.; Lachlan-Cope, T.; Gallagher, M. W.; Crosier, J.; Bower, K. N.; Ladkin, R. S.; Dorsey, J. R.

    2012-07-01

    In-situ aircraft observations of ice crystal concentrations in Antarctic clouds are presented for the first time. Orographic, layer and wave clouds around the Antarctic Peninsula and Larsen Ice shelf regions were penetrated by the British Antarctic Survey's Twin Otter Aircraft, which was equipped with modern cloud physics probes. The clouds studied were mostly in the free troposphere and hence ice crystals blown from the surface are unlikely to have been a major source for the ice phase. The temperature range covered by the experiments was 0 to -21°C. The clouds were found to contain supercooled liquid water in most regions and at heterogeneous ice formation temperatures ice crystal concentrations (60 s averages) were often less than 0.07 l-1, although values up to 0.22 l-1 were observed. Estimates of observed aerosol concentrations were used as input into the DeMott et al., 2010 ice nuclei (IN) parameterisation. The observed ice crystal number concentrations were generally in broad agreement with the IN predictions, although on the whole the predicted values were higher. Possible reasons for this are discussed and include the lack of IN observations in this region with which to characterise the parameterisation, and/or problems in relating ice concentration measurements to IN concentrations. Other IN parameterisations significantly overestimated the number of ice particles. Generally ice particle concentrations were much lower than found in clouds in middle latitudes for a given temperature. Higher ice crystal concentrations were sometimes observed at temperatures warmer than -9 °C, with values of several per litre reached. These were attributable to secondary ice particle production by the Hallett Mossop process. Even in this temperature range it was observed that there were regions with little or no ice that were dominated by supercooled liquid water. It is likely that in some cases this was due to a lack of seeding ice crystals to act as rimers to initiate

  7. In-situ aircraft observations of ice concentrations within clouds over the Antarctic Peninsula and Larsen Ice Shelf

    NASA Astrophysics Data System (ADS)

    Grosvenor, D. P.; Choularton, T. W.; Lachlan-Cope, T.; Gallagher, M. W.; Crosier, J.; Bower, K. N.; Ladkin, R. S.; Dorsey, J. R.

    2012-12-01

    In-situ aircraft observations of ice crystal concentrations in Antarctic clouds are presented for the first time. Orographic, layer and wave clouds around the Antarctic Peninsula and Larsen Ice shelf regions were penetrated by the British Antarctic Survey's Twin Otter aircraft, which was equipped with modern cloud physics probes. The clouds studied were mostly in the free troposphere and hence ice crystals blown from the surface are unlikely to have been a major source for the ice phase. The temperature range covered by the experiments was 0 to -21 °C. The clouds were found to contain supercooled liquid water in most regions and at heterogeneous ice formation temperatures ice crystal concentrations (60 s averages) were often less than 0.07 l-1, although values up to 0.22 l-1 were observed. Estimates of observed aerosol concentrations were used as input into the DeMott et al. (2010) ice nuclei (IN) parameterisation. The observed ice crystal number concentrations were generally in broad agreement with the IN predictions, although on the whole the predicted values were higher. Possible reasons for this are discussed and include the lack of IN observations in this region with which to characterise the parameterisation, and/or problems in relating ice concentration measurements to IN concentrations. Other IN parameterisations significantly overestimated the number of ice particles. Generally ice particle concentrations were much lower than found in clouds in middle latitudes for a given temperature. Higher ice crystal concentrations were sometimes observed at temperatures warmer than -9 °C, with values of several per litre reached. These were attributable to secondary ice particle production by the Hallett Mossop process. Even in this temperature range it was observed that there were regions with little or no ice that were dominated by supercooled liquid water. It is likely that in some cases this was due to a lack of seeding ice crystals to act as rimers to initiate

  8. 14 CFR 135.227 - Icing conditions: Operating limitations.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... limitations. (a) No pilot may take off an aircraft that has frost, ice, or snow adhering to any rotor blade... frost under the wing in the area of the fuel tanks if authorized by the FAA. (b) No certificate holder... such that frost, ice, or snow may reasonably be expected to adhere to the airplane unless the pilot...

  9. 14 CFR 135.227 - Icing conditions: Operating limitations.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... limitations. (a) No pilot may take off an aircraft that has frost, ice, or snow adhering to any rotor blade... frost under the wing in the area of the fuel tanks if authorized by the FAA. (b) No certificate holder... such that frost, ice, or snow may reasonably be expected to adhere to the airplane unless the pilot...

  10. 14 CFR 135.227 - Icing conditions: Operating limitations.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... limitations. (a) No pilot may take off an aircraft that has frost, ice, or snow adhering to any rotor blade... frost under the wing in the area of the fuel tanks if authorized by the FAA. (b) No certificate holder... such that frost, ice, or snow may reasonably be expected to adhere to the airplane unless the pilot...

  11. 14 CFR 135.227 - Icing conditions: Operating limitations.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... limitations. (a) No pilot may take off an aircraft that has frost, ice, or snow adhering to any rotor blade... frost under the wing in the area of the fuel tanks if authorized by the FAA. (b) No certificate holder... such that frost, ice, or snow may reasonably be expected to adhere to the airplane unless the pilot...

  12. Current Methods for Modeling and Simulating Icing Effects on Aircraft Performance, Stability and Control

    NASA Technical Reports Server (NTRS)

    Ralvasky, Thomas P.; Barnhart, Billy P.; Lee, Sam

    2008-01-01

    Icing alters the shape and surface characteristics of aircraft components, which results in altered aerodynamic forces and moments caused by air flow over those iced components. The typical effects of icing are increased drag, reduced stall angle of attack, and reduced maximum lift. In addition to the performance changes, icing can also affect control surface effectiveness, hinge moments, and damping. These effects result in altered aircraft stability and control and flying qualities. Over the past 80 years, methods have been developed to understand how icing affects performance, stability and control. Emphasis has been on wind tunnel testing of two-dimensional subscale airfoils with various ice shapes to understand their effect on the flow field and ultimately the aerodynamics. This research has led to wind tunnel testing of subscale complete aircraft models to identify the integrated effects of icing on the aircraft system in terms of performance, stability, and control. Data sets of this nature enable pilot in the loop simulations to be performed for pilot training, or engineering evaluation of system failure impacts or control system design.

  13. Current Methods Modeling and Simulating Icing Effects on Aircraft Performance, Stability, Control

    NASA Technical Reports Server (NTRS)

    Ratvasky, Thomas P.; Barnhart, Billy P.; Lee, Sam

    2010-01-01

    Icing alters the shape and surface characteristics of aircraft components, which results in altered aerodynamic forces and moments caused by air flow over those iced components. The typical effects of icing are increased drag, reduced stall angle of attack, and reduced maximum lift. In addition to the performance changes, icing can also affect control surface effectiveness, hinge moments, and damping. These effects result in altered aircraft stability and control and flying qualities. Over the past 80 years, methods have been developed to understand how icing affects performance, stability, and control. Emphasis has been on wind-tunnel testing of two-dimensional subscale airfoils with various ice shapes to understand their effect on the flowfield and ultimately the aerodynamics. This research has led to wind-tunnel testing of subscale complete aircraft models to identify the integrated effects of icing on the aircraft system in terms of performance, stability, and control. Data sets of this nature enable pilot-in-the-loop simulations to be performed for pilot training or engineering evaluation of system failure impacts or control system design.

  14. An experimental and theoretical study of the ice accretion process during artificial and natural icing conditions

    NASA Technical Reports Server (NTRS)

    Kirby, Mark S.; Hansman, R. John

    1988-01-01

    Real-time measurements of ice growth during artificial and natural icing conditions were conducted using an ultrasonic pulse-echo technique. This technique allows ice thickness to be measured with an accuracy of + or - 0.5 mm; in addition, the ultrasonic signal characteristics may be used to detect the presence of liquid on the ice surface and hence discern wet and dry ice growth behavior. Ice growth was measured on the stagnation line of a cylinder exposed to artificial icing conditions in the NASA Lewis Icing Research Tunnel (IRT), and similarly for a cylinder exposed in flight to natural icing conditions. Ice thickness was observed to increase approximately linearly with exposure time during the initial icing period. The ice accretion rate was found to vary with cloud temperature during wet ice growth, and liquid runback from the stagnation region was inferred. A steady-state energy balance model for the icing surface was used to compare heat transfer characteristics for IRT and natural icing conditions. Ultrasonic measurements of wet and dry ice growth observed in the IRT and in flight were compared with icing regimes predicted by a series of heat transfer coefficients. The heat transfer magnitude was generally inferred to be higher for the IRT than for the natural icing conditions encountered in flight. An apparent variation in the heat transfer magnitude was also observed for flights conducted through different natural icing-cloud formations.

  15. A Simplified Instrument for Recording and Indicating Frequency and Intensity of Icing Conditions Encountered in Flight

    NASA Technical Reports Server (NTRS)

    Perkins, Porter J; Mccullough, Stuart; Lewis, Ralph D

    1951-01-01

    An instrument for recording and indicating the frequency and intensity of aircraft icing conditions encountered in flight has been developed by the NACA Lewis Laboratory to obtain statistical icing data over world-wide air routes during routine airline operations. The operation of the instrument is based on the creation of a differential pressure between an ice-free total-pressure system and a total-pressure system in which small total-pressure holes vented to static pressure are allowed to plug with ice accretion. The simplicity of this operating principle permits automatic operation, and provides relative freedom from maintenance and operating problems. The complete unit weighing only 18 pounds records icing rate, airspeed, and altitude on photographic film and provides visual indications of icing intensity to the pilot.

  16. An Experimental Investigation on the Impingement of Water Droplets onto Superhydrophobic Surfaces Pertinent to Aircraft Icing Phenomena

    NASA Astrophysics Data System (ADS)

    Li, Haixing; Waldman, Rye; Hu, Hui

    2015-11-01

    Superhydrophobic surfaces have self-cleaning properties that make them promising candidates as anti-icing solutions for various engineering applications, including aircraft anti-/de-icing. However, under sufficient external pressure, the liquid water on the surface can transition to a wetted state, defeating the self-cleaning properties of superhydrpphobic surfaces. In the present study, an experimental investigation was conducted to quantify the transient behavior of water droplets impinging onto test surfaces with different hydrophobicity properties under different environmental icing conditions. The experiments were performed in the Icing Research Tunnel of Iowa State University (IRT-ISU) with a NACA0012 airfoil. In addition to using a high-speed imaging system to reveal transient behavior of water droplets impinging onto test surfaces with different hydrophobicity properties, an IR thermometry was also used to quantify the unsteady heat transfer and dynamic phase changing process within the water droplets after impingement onto the test plates with different frozen cold temperatures. The high-speed imaging results were correlated with the quantitatively temperature measurements to elucidate underlying physics in order to gain further insight into the underlying physics pertinent to aircraft icing phenomena. The research work is partially supported by NASA with grant number NNX12AC21A and National Science Foundation under award numbers of CBET-1064196 and CBET-1435590.

  17. Experimental evidence for modifying the current physical model for ice accretion on aircraft surfaces

    NASA Technical Reports Server (NTRS)

    Olsen, W.; Walker, E.

    1986-01-01

    Closeup movies, still photographs, and other experimental data suggest that the current physical model for ice accretion needs significant modification. At aircraft airspeeds there was no flow of liquid over the surface of the ice after a short initial flow, even at barely subfreezing temperatures. Instead, there were very large stationary drops on the ice surface that lose water from their bottoms by freezing and replenish their liquid by catching the microscopic cloud droplets. This observation disagrees with the existing physical model, which assumes there is a thin liquid film continuously flowing over the ice surface. With no such flow, the freezing-fraction concept of the model fails when a mass balance is performed on the surface water. Rime ice does, as the model predicts, form when the air temperature is low enough to cause the cloud droplets to freeze almost immediately on impact. However, the characteristic shapes of horn-glaze ice or rime ice are primarily caused by the ice shape affecting the airflow locally and consequently the droplet catch and the resulting ice shape. Ice roughness greatly increases the heat transfer coefficient, stops the movement of drops along the surface, and may also affect the airflow initially and thereby the droplet catch. At high subreezing temperatures the initial flow and shedding of surface drops have a large effect on the ice shape. At the incipient freezing limit, no ice forms.

  18. Remote Sensing of In-Flight Icing Conditions: Operational, Meteorological, and Technological Considerations

    NASA Technical Reports Server (NTRS)

    Ryerson, Charles C.

    2000-01-01

    Remote-sensing systems that map aircraft icing conditions in the flight path from airports or aircraft would allow icing to be avoided and exited. Icing remote-sensing system development requires consideration of the operational environment, the meteorological environment, and the technology available. Operationally, pilots need unambiguous cockpit icing displays for risk management decision-making. Human factors, aircraft integration, integration of remotely sensed icing information into the weather system infrastructures, and avoid-and-exit issues need resolution. Cost, maintenance, power, weight, and space concern manufacturers, operators, and regulators. An icing remote-sensing system detects cloud and precipitation liquid water, drop size, and temperature. An algorithm is needed to convert these conditions into icing potential estimates for cockpit display. Specification development requires that magnitudes of cloud microphysical conditions and their spatial and temporal variability be understood at multiple scales. The core of an icing remote-sensing system is the technology that senses icing microphysical conditions. Radar and microwave radiometers penetrate clouds and can estimate liquid water and drop size. Retrieval development is needed; differential attenuation and neural network assessment of multiple-band radar returns are most promising to date. Airport-based radar or radiometers are the most viable near-term technologies. A radiometer that profiles cloud liquid water, and experimental techniques to use radiometers horizontally, are promising. The most critical operational research needs are to assess cockpit and aircraft system integration, develop avoid-and-exit protocols, assess human factors, and integrate remote-sensing information into weather and air traffic control infrastructures. Improved spatial characterization of cloud and precipitation liquid-water content, drop-size spectra, and temperature are needed, as well as an algorithm to

  19. Flight test report of the NASA icing research airplane: Performance, stability, and control after flight through natural icing conditions

    NASA Technical Reports Server (NTRS)

    Jordan, J. L.; Platz, S. J.; Schinstock, W. C.

    1986-01-01

    Flight test results are presented documenting the effect of airframe icing on performance and stability and control of a NASA DHC-6 icing research aircraft. Kohlman System Research, Inc., provided the data acquisition system and data analysis under contract to NASA. Performance modeling methods and MMLE techniques were used to determine the effects of natural ice on the aircraft. Results showed that ice had a significant effect on the drag coefficient of the aircraft and a modest effect on the MMLE derived longitudinal stability coefficients (code version MMLE). Data is also presented on asymmetric power sign slip maneuvers showing rudder floating characteristics with and without ice on the vertical stabilizer.

  20. Discrete Surface Evolution and Mesh Deformation for Aircraft Icing Applications

    NASA Technical Reports Server (NTRS)

    Thompson, David; Tong, Xiaoling; Arnoldus, Qiuhan; Collins, Eric; McLaurin, David; Luke, Edward; Bidwell, Colin S.

    2013-01-01

    Robust, automated mesh generation for problems with deforming geometries, such as ice accreting on aerodynamic surfaces, remains a challenging problem. Here we describe a technique to deform a discrete surface as it evolves due to the accretion of ice. The surface evolution algorithm is based on a smoothed, face-offsetting approach. We also describe a fast algebraic technique to propagate the computed surface deformations into the surrounding volume mesh while maintaining geometric mesh quality. Preliminary results presented here demonstrate the ecacy of the approach for a sphere with a prescribed accretion rate, a rime ice accretion, and a more complex glaze ice accretion.

  1. Numerical simulation of two-dimensional heat transfer in composite bodies with application to de-icing of aircraft components. Ph.D. Thesis. Final Report

    NASA Technical Reports Server (NTRS)

    Chao, D. F. K.

    1983-01-01

    Transient, numerical simulations of the de-icing of composite aircraft components by electrothermal heating were performed for a two dimensional rectangular geometry. The implicit Crank-Nicolson formulation was used to insure stability of the finite-difference heat conduction equations and the phase change in the ice layer was simulated using the Enthalpy method. The Gauss-Seidel point iterative method was used to solve the system of difference equations. Numerical solutions illustrating de-icer performance for various composite aircraft structures and environmental conditions are presented. Comparisons are made with previous studies. The simulation can also be used to solve a variety of other heat conduction problems involving composite bodies.

  2. Conditions for bubble elongation in cold ice-sheet ice

    USGS Publications Warehouse

    Alley, R.B.; Fitzpatrick, J.J.

    1999-01-01

    Highly elongated bubbles are sometimes observed in ice-sheet ice. Elongation is favored by rapid ice deformation, and opposed by diffusive processes. We use simple models to show that vapor transport dominates diffusion except possibly very close to the melting point, and that latent-heat effects are insignificant. Elongation is favored by larger bubbles at pore close-off, but is nearly independent of bubble compression below close-off. The simple presence of highly elongated bubbles indicates only that a critical ice-strain rate has been exceeded for significant time, and provides no information on possible disruption of stratigraphic continuity by ice deformation.

  3. Progress in the Development of Practical Remote Detection of Icing Conditions

    NASA Technical Reports Server (NTRS)

    Reehorst, Andrew; Politovich, Marcia K.; Zednik, Stephan; Isaac, George A.; Cober, Stewart

    2006-01-01

    The NASA Icing Remote Sensing System (NIRSS) has been under definition and development at NASA Glenn Research Center since 1997. The goal of this development activity is to produce and demonstrate the required sensing and data processing technologies required to accurately remotely detect and measure icing conditions aloft. As part of that effort NASA has teamed with NCAR to develop software to fuse data from multiple instruments into a single detected icing condition product. The multiple instrument approach utilizes a X-band vertical staring radar, a multifrequency microwave, and a lidar ceilometer. The radar data determine cloud boundaries, the radiometer determines the sub-freezing temperature heights and total liquid water content, and the ceilometer refines the lower cloud boundary. Data is post-processed with a LabVIEW program with a resultant supercooled liquid water profile and aircraft hazard depiction. Ground-based, remotely-sensed measurements and in-situ measurements from research aircraft were gathered during the international 2003-2004 Alliance Icing Research Study (AIRS II). Comparisons between the remote sensing system s fused icing product and the aircraft measurements are reviewed here. While there are areas where improvement can be made, the cases examined suggest that the fused sensor remote sensing technique appears to be a valid approach.

  4. Impacts of alternative fuels in aviation on microphysical aerosol properties and predicted ice nuclei concentration at aircraft cruise altitude

    NASA Astrophysics Data System (ADS)

    Weinzierl, B.; D'Ascoli, E.; Sauer, D. N.; Kim, J.; Scheibe, M.; Schlager, H.; Moore, R.; Anderson, B. E.; Ullrich, R.; Mohler, O.; Hoose, C.

    2015-12-01

    In the past decades air traffic has been substantially growing affecting air quality and climate. According to the International Civil Aviation Authority (ICAO), in the next few years world passenger and freight traffic is expected to increase annually by 6-7% and 4-5%, respectively. One possibility to reduce aviation impacts on the atmosphere and climate might be the replacement of fossil fuels by alternative fuels. However, so far the effects of alternative fuels on particle emissions from aircraft engines and their ability to form contrails remain uncertain. To study the effects of alternative fuels on particle emissions and the formation of contrails, the Alternative Fuel Effects on Contrails and Cruise Emissions (ACCESS) field experiment was conducted in California. In May 2014, the DLR Falcon 20 and the NASA HU-25 jet aircraft were instrumented with an extended aerosol and trace gas payload probing different types of fuels including JP-8 and JP-8 blended with HEFA (Hydroprocessed Esters and Fatty Acids) while the NASA DC8 aircraft acted as the source aircraft for ACCESS-2. Emission measurements were taken in the DC8 exhaust plumes at aircraft cruise level between 9-12 km altitude and at distances between 50 m and 20 km behind the DC8 engines. Here, we will present results from the ACCESS-2 aerosol measurements which show a 30-60% reduction of the non-volatile (mainly black carbon) particle number concentration in the aircraft exhaust for the HEFA-blend compared to conventional JP-8 fuel. Size-resolved particle emission indices show the largest reductions for larger particle sizes suggesting that the HEFA blend contains fewer and smaller black carbon particles. We will combine the airborne measurements with a parameterization of deposition nucleation developed during a number of ice nucleation experiments at the AIDA chamber in Karlsruhe and discuss the impact of alternative fuels on the abundance of potential ice nuclei at cruise conditions.

  5. Lightning Discharges to Aircraft and Associated Meteorological Conditions

    NASA Technical Reports Server (NTRS)

    Harrison, L P

    1946-01-01

    A summary is given of information on atmospheric electrical discharges to aircraft and associated meteorological conditions. Information is given that is designed to give a fairly comprehensive view of the underlying principles of meteorology and atmospheric electricity. Of special interest to pilots are lists of procedures of flight conduct and aircraft maintenance recommended foe avoiding or minimizing the hazards of disruptive electrical discharges and other severe conditions near thunderstorms.

  6. A NASA/University/Industry Consortium for Research on Aircraft Ice Protection

    NASA Technical Reports Server (NTRS)

    Zumwalt, Glen W.

    1989-01-01

    From 1982 through 1987, an unique consortium was functioning which involved government (NASA), academia (Wichita State Univ.) and twelve industries. The purpose was the development of a better ice protection systems for aircraft. The circumstances which brought about this activity are described, the formation and operation recounted, and the effectiveness of the ventue evaluated.

  7. Estimation of longitudinal stability and control derivatives for an icing research aircraft from flight data

    NASA Technical Reports Server (NTRS)

    Batterson, James G.; Omara, Thomas M.

    1989-01-01

    The results of applying a modified stepwise regression algorithm and a maximum likelihood algorithm to flight data from a twin-engine commuter-class icing research aircraft are presented. The results are in the form of body-axis stability and control derivatives related to the short-period, longitudinal motion of the aircraft. Data were analyzed for the baseline (uniced) and for the airplane with an artificial glaze ice shape attached to the leading edge of the horizontal tail. The results are discussed as to the accuracy of the derivative estimates and the difference between the derivative values found for the baseline and the iced airplane. Additional comparisons were made between the maximum likelihood results and the modified stepwise regression results with causes for any discrepancies postulated.

  8. 14 CFR 135.227 - Icing conditions: Operating limitations.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... aircraft that has frost, ice, or snow adhering to any rotor blade, propeller, windshield, wing, stabilizing... frost adhering to the wings, or stabilizing or control surfaces, if the frost has been polished to make it smooth. (2) Takeoffs may be made with frost under the wing in the area of the fuel tanks...

  9. Development of Three-Dimensional Flow Code Package to Predict Performance and Stability of Aircraft with Leading Edge Ice Contamination

    NASA Technical Reports Server (NTRS)

    Strash, D. J.; Summa, J. M.

    1996-01-01

    In the work reported herein, a simplified, uncoupled, zonal procedure is utilized to assess the capability of numerically simulating icing effects on a Boeing 727-200 aircraft. The computational approach combines potential flow plus boundary layer simulations by VSAERO for the un-iced aircraft forces and moments with Navier-Stokes simulations by NPARC for the incremental forces and moments due to iced components. These are compared with wind tunnel force and moment data, supplied by the Boeing Company, examining longitudinal flight characteristics. Grid refinement improved the local flow features over previously reported work with no appreciable difference in the incremental ice effect. The computed lift curve slope with and without empennage ice matches the experimental value to within 1%, and the zero lift angle agrees to within 0.2 of a degree. The computed slope of the un-iced and iced aircraft longitudinal stability curve is within about 2% of the test data. This work demonstrates the feasibility of a zonal method for the icing analysis of complete aircraft or isolated components within the linear angle of attack range. In fact, this zonal technique has allowed for the viscous analysis of a complete aircraft with ice which is currently not otherwise considered tractable.

  10. The crystal structure of ice under mesospheric conditions

    NASA Astrophysics Data System (ADS)

    Murray, Benjamin J.; Malkin, Tamsin L.; Salzmann, Christoph G.

    2015-05-01

    Ice clouds form in the summer high latitude mesopause region, which is the coldest part of the Earth's atmosphere. At these very low temperatures (<150 K) ice can exist in metastable forms, but the nature of these ices remains poorly understood. In this paper we show that ice which is grown at mesospherically relevant temperatures does not have a structure corresponding to the well-known hexagonal form or the metastable cubic form. Instead, the ice which forms under mesospheric conditions is a material in which cubic and hexagonal sequences of ice are randomly arranged to produce stacking disordered ice (ice Isd). The structure of this ice is in the trigonal crystal system, rather than the cubic or hexagonal systems, and is expected to produce crystals with aspect ratios consistent with lidar observations.

  11. Root damage analysis of aircraft engine blade subject to ice impact

    NASA Technical Reports Server (NTRS)

    Reddy, E. S.; Abumeri, G. H.; Chamis, C. C.; Murthy, P. L. N.

    1992-01-01

    The blade root response due to ice impact on an engine blade is simulated using the NASA in-house code BLASIM. The ice piece is modeled as an equivalent spherical object impacting on the leading edge of the blade and has the velocity opposite to that of the aircraft with direction parallel to the engine axis. The effect of ice impact is considered to be an impulse load on the blade with its amplitude computed based on the momentum transfer principle. The blade response due to the impact is carried out by modal superposition using the first three modes. The maximum dynamic stresses at the blade root are computed at the quarter cycle of the first natural frequency. A combined stress failure function based on modified distortion energy is used to study the spanwise bending damage response at the blade root. That damage function reaches maximum value for very low ice speeds and increases steeply with increases in engine speed.

  12. Current Icing Potential: Algorithm Description and Comparison with Aircraft Observations.

    NASA Astrophysics Data System (ADS)

    Bernstein, Ben C.; McDonough, Frank; Politovich, Marcia K.; Brown, Barbara G.; Ratvasky, Thomas P.; Miller, Dean R.; Wolff, Cory A.; Cunning, Gary

    2005-07-01

    The “current icing potential” (CIP) algorithm combines satellite, radar, surface, lightning, and pilot-report observations with model output to create a detailed three-dimensional hourly diagnosis of the potential for the existence of icing and supercooled large droplets. It uses a physically based situational approach that is derived from basic and applied cloud physics, combined with forecaster and onboard flight experience from field programs. Both fuzzy logic and decision-tree logic are applied in this context. CIP determines the locations of clouds and precipitation and then estimates the potential for the presence of supercooled liquid water and supercooled large droplets within a given airspace. First developed in the winter of 1997/98, CIP became an operational National Weather Service and Federal Aviation Administration product in 2002, providing real-time diagnoses that allow users to make route-specific decisions to avoid potentially hazardous icing. The CIP algorithm, its individual components, and the logic behind them are described.

  13. Comparison of TWP-ICE Satellite and Field Campaign Aircraft Derived Cloud Properties

    NASA Technical Reports Server (NTRS)

    Ayers, J. K.; Minnis, Patrick; Spangenberg, Douglas A.; Nordeen, Michele L.; Khaiyer, Mandana M.; Palikonda, Rabindra; Nguyen, Louis; Phan, Dung N.

    2007-01-01

    Cloud and radiation products derived from the MTSAT-1R satellite have been developed for TWP-ICE. These include pixel-level, gridded, and ground site and aircraft matched. These products are available from the Langley website and the ARM data center. As shown in Figs 2, and 4-6, these products compare favorably with in-situ ground and aircraft based measurements. With additional quantitative validation these products can provide valuable information about tropical convection and its impact on the radiation budget and climate. As new algorithm improvements, such as multi-layer cloud detection, are implemented these products will be reprocessed and updated.

  14. Real-time measurement of ice growth during simulated and natural icing conditions using ultrasonic pulse-echo techniques

    NASA Technical Reports Server (NTRS)

    Hansman, R. J., Jr.; Kirby, M. S.

    1986-01-01

    Results of tests to measure ice accretion in real-time using ultrasonic pulse-echo techniques are presented. Tests conducted on a 10.2 cm diameter cylinder exposed to simulated icing conditions in the NASA Lewis Icing Research Tunnel and on an 11.4 cm diameter cylinder exposed to natural icing conditions in flight are described. An accuracy of + or - 0.5 mm is achieved for real-time ice thickness measurements. Ice accretion rate is determined by differentiating ice thickness with respect to time. Icing rates measured during simulated and natural icing conditions are compared and related to icing cloud parameters. The ultrasonic signal characteristics are used to detect the presence of surface water on the accreting ice shape and thus to distinguish between dry ice growth and wet growth. The surface roughness of the accreted ice is shown to be related to the width of the echo signal received from the ice surface.

  15. Navier-Stokes Analysis of the Flowfield Characteristics of an Ice Contaminated Aircraft Wing

    NASA Technical Reports Server (NTRS)

    Chung, J.; Choo, Y.; Reehorst, A.; Potapczuk, M.; Slater, J.

    1999-01-01

    An analytical study was performed as part of the NASA Lewis support of a National Transportation Safety Board (NTSB) aircraft accident investigation. The study was focused on the performance degradation associated with ice contamination on the wing of a commercial turbo-prop-powered aircraft. Based upon the results of an earlier numerical study conducted by the authors, a prominent ridged-ice formation on the subject aircraft wing was selected for detailed flow analysis using 2-dimensional (2-D), as well as, 3-dimensional (3-D) Navier-Stokes computations. This configuration was selected because it caused the largest lift decrease and drag increase among all the ice shapes investigated in the earlier study. A grid sensitivity test was performed to find out the influence of grid spacing on the lift, drag, and associated angle-of-attack for the maximum lift (C(sub lmax)). This study showed that grid resolution is important and a sensitivity analysis is an essential element of the process in order to assure that the final solution is independent of the grid. The 2-D results suggested that a severe stability and control difficulty could have occurred at a slightly higher angle-of-attack (AOA) than the one recorded by the Flight Data Recorder (FDR). This stability and control problem was thought to have resulted from a decreased differential lift on the wings with respect to the normal loading for the configuration. The analysis also indicated that this stability and control problem could have occurred whether or not natural ice shedding took place. Numerical results using an assumed 3-D ice shape showed an increase of the angle at which this phenomena occurred of about 4 degrees. As it occurred with the 2-D case, the trailing edge separation was observed but started only when the AOA was very close to the angle at which the maximum lift occurred.

  16. Evaluating and Constraining Ice Cloud Parameterizations in CAM5 using Aircraft Measurements from the SPARTICUS Campaign

    SciTech Connect

    Zhang, Kai; Liu, Xiaohong; Wang, Minghuai; Comstock, Jennifer M.; Mitchell, David; Mishra, Subhashree; Mace, Gerald G.

    2013-05-14

    This study uses aircraft measurements of relative humidity and ice crystal size distribution collected in synoptic cirrus during the SPARTICUS (Small PARTicles In CirrUS) field campaign to evaluate and constrain ice cloud parameterizations in the Community Atmosphere Model version 5. The probability density function (PDF) of ice crystal number concentration (Ni) derived from high frequency (1 Hz) measurements features a strong dependence on ambient temperature. As temperature decreases from -35°C to -62°C, the peak in the PDF shifts from 10-20 L-1 to 200-1000 L-1, while the ice crystal number concentration shows a factor of 6-7 increase. Model simulations are performed with two different insitu ice nucleation schemes. One of the schemes can reproduce a clear increase of Ni with decreasing temperature, by using either an observation based ice nuclei spectrum or a classical theory based spectrum with a relatively low (5%-10%) maximum freezing ratio for dust aerosols. The simulation with the other scheme, which assumes a high maximum freezing ratio (100%), shows much weaker temperature dependence of Ni. Simulations are also performed to test empirical parameters related to water vapor deposition and the auto-conversion of ice crystals to snow. Results show that a value between 0.05 and 0.1 for the water vapor deposition coefficient and 250 um for the critical ice crystal size can produce good agreements between model simulation and the SPARTICUS measurements in terms of ice crystal number concentration and effective radius. The climate impact of perturbing these parameters is also discussed.

  17. Icing conditions over Northern Eurasia in changing climate

    NASA Astrophysics Data System (ADS)

    Bulygina, Olga N.; Arzhanova, Natalia M.; Groisman, Pavel Ya

    2015-02-01

    Icing conditions, particularly in combination with wind, affect greatly the operation of overhead communication and transmission lines causing serious failures, which result in tremendous economic damage. Icing formation is dangerous to agriculture, forestry, high seas fishery, for land and off coast man-made infrastructure. Quantitative icing characteristics such as weight, thickness, and duration are very important for the economy and human wellbeing when their maximum values exceed certain thresholds. Russian meteorological stations perform both visual and instrumental monitoring of icing deposits. Visual monitoring is ocular estimation of the type and intensity of icing and the date of ice appearance and disappearance. Instrumental monitoring is performed by ice accretion indicator that in addition to the type, intensity and duration of ice deposits reports also their weight and size. We used observations at 958 Russian stations for the period 1977-2013 to analyze changes in the ice formation frequency at individual meteorological stations and on the territory of quasi-homogeneous climatic regions in Russia. It was found that hoar frosts are observed in most parts of Russia, but icing only occurs in European Russia and the Far East. On the Arctic coast of Russia, this phenomenon can even be observed in summer months. Statistically significant decreasing trends in occurrence of icing and hoar frost events are found over most of Russia. An increasing trend in icing weights (IWs) was found in the Atlantic Arctic region in autumn. Statistically significant large negative trends in IWs were found in the Pacific Arctic in winter and spring.

  18. Extraction of aerodynamic parameters for aircraft at extreme flight conditions

    NASA Technical Reports Server (NTRS)

    Iliff, K. W.

    1985-01-01

    The maximum likelihood estimator has been used to extract stability and control derivatives from flight data for many years. Most of the literature on aircraft estimation concentrates on new developments and applications, assuming familiarity with basic concepts. This paper briefly discusses the maximum likelihood estimator and the aircraft equations of motion that the estimator uses. The current strength and limitations associated with obtaining flight-determined aerodynamic coefficients in extreme flight conditions is assessed. The importance of the careful combining of wind tunnel results (or calculations) and flight results and the thorough evaluation of the mathematical model is emphasized. The basic concepts of minimization and estimation are examined for a simple computed aircraft example, and the cost functions that are to be minimized during estimation are defined and discussed. Graphic representations of the cost functions are given to help illustrate the minimization process. Finally, the basic concepts are generalized, and estimation of stability and control derivatives from flight data is discussed.

  19. Extraction of aerodynamic parameters for aircraft at extreme flight conditions

    NASA Technical Reports Server (NTRS)

    Iliff, K. W.

    1985-01-01

    The maximum likelihood estimator was used to extract stability and control derivatives from flight data for many years. Most of the literature on aircraft estimation concentrates on new development and applications, assuming familiarity with basic concepts. The maximum likelihood estimator and the aircraft equations of motion that the estimator uses are discussed. The current strength and limitations associated with obtaining flight-determined aerodynamic coefficients in extreme flight conditions are assessed. The importance of the careful combining of wind tunnel results (or calculations) and flight results and the thorough evaluation of the mathematical model is emphasized. The basic concepts of minimization and estimation are examined for a simple computed aircraft example, and the cost functions that are to be minimized during estimation are defined and discussed. Graphic representations of the cost functions are given to help illustrate the minimization process. Finally, the basic concepts are generalized, and estimation of stability and control derivatives from flight data is discussed.

  20. A novel actuator phasing method for ultrasonic de-icing of aircraft structures

    NASA Astrophysics Data System (ADS)

    Borigo, Cody J.

    Aircraft icing is a critical concern for commercial and military rotorcraft and fixed-wing aircraft. In-flight icing can lead to dramatic decreases in lift and increases in drag that have caused more than a thousand deaths and hundreds of accidents over the past three decades alone. Current ice protection technologies have substantial drawbacks due to weight, power consumption, environmental concerns, or incompatibility with certain structures. In this research, an actuator phasing method for ultrasonic de-icing of aircraft structures was developed and tested using a series of finite element models, 3D scanning laser Doppler vibrometer measurements, and experimental de-icing tests on metallic and composite structures including plates and airfoils. An independent actuator analysis method was developed to allow for practical evaluation of many actuator phasing scenarios using a limited number of finite element models by properly calculating the phased stress fields and electromechanical impedance curves using a complex coupled impedance model. A genetic algorithm was utilized in conjunction with a series of finite element models to demonstrate that phase inversion, in which only in-phase and anti-phase signal components are applied to actuators, can be utilized with a small number of phasing combinations to achieve substantial improvements in de-icing system coverage. Finite element models of a 48"-long airfoil predicted that phase inversion with frequency sweeping can provide an improvement in the shear stress coverage levels of up to 90% compared to frequency sweeping alone. Experimental evaluation of the phasing approach on an icing grid showed a 189% improvement in de-icing coverage compared to frequency sweeping alone at comparable power levels. 3D scanning laser Doppler vibrometer measurements confirmed the increased variation in the surface vibration field induced by actuator phasing compared to unphased frequency sweeping. Additional contributions were made

  1. Analysis of a Hovering Rotor in Icing Conditions

    NASA Technical Reports Server (NTRS)

    Narducci, Robert; Kreeger, Richard E.

    2012-01-01

    A high fidelity analysis method is proposed to evaluate the ice accumulation and the ensuing rotor performance degradation for a helicopter flying through an icing cloud. The process uses computational fluid dynamics (CFD) coupled to a rotorcraft comprehensive code to establish the aerodynamic environment of a trimmed rotor prior to icing. Based on local aerodynamic conditions along the rotor span and accounting for the azimuthal variation, an ice accumulation analysis using NASA's Lewice3D code is made to establish the ice geometry. Degraded rotor performance is quantified by repeating the high fidelity rotor analysis with updates which account for ice shape and mass. The process is applied on a full-scale UH-1H helicopter in hover using data recorded during the Helicopter Icing Flight Test Program.

  2. The Mesoscale Morphologies of Ice Films: Porous and Biomorphic Forms of Ice under Astrophysical Conditions

    NASA Astrophysics Data System (ADS)

    Cartwright, Julyan H. E.; Escribano, Bruno; Sainz-Diaz, C. Ignacio

    2008-11-01

    We present the results of experiments in which we grow submicrometer- to millimeter-thick ice films at temperatures of 6-220 K at low pressures in situ in a cryo environmental scanning electron microscope. We find that ice films show pronounced morphologies at the mesoscale similar to those previously described in films of ceramics, semiconductors, and metals; materials with quite different material properties to ice. Our experiments are aimed at revealing the mesoscale morphologies of amorphous and crystalline ice with regard to astrophysical environments, as the conditions in which the ice films grow in our experiments are those under which exists most extraterrestrial ice. The porosity on the mesoscale of many of the morphologies is notable in this regard; a further intriguing finding is that these ice films can emulate biological forms.

  3. Low-level flow conditions hazardous to aircraft

    NASA Technical Reports Server (NTRS)

    Alexander, M. B.; Camp, D. W.

    1983-01-01

    Low level flow conditions known to be hazardous to aircraft during takeoff/climbout and approach/landing operations are turbulence, wind shear, and vertical motion. These conditions can and frequently do occur separately and in combinations. The identification and selection were completed of representative data cases to determine magnitude, frequency, duration, and simultaneity of occurrence of turbulence (gustiness and gust factor), wind shear (speed and direction), and vertical motion (updraft and downdraft), along with temperature inversions. New representations of temporal and spatial variations in the atmospheric boundary layer were developed. Efforts continued relative to low level flow conditions where published results imply strong vertical shear with virtually no horizontal shear and where order of magnitude analyses of the equations of motion for an aircraft illustrates that low values of horizontal shear (along the flight path) are much more hazardous than larger values of vertical wind shear (altitude).

  4. Large-area Ice Sheet and Sea Ice mapping from High-altitude Aircraft: Examples from the LVIS Sensor

    NASA Astrophysics Data System (ADS)

    Blair, J. B.; Hofton, M. A.; Rabine, D. L.

    2010-12-01

    High altitude airborne surveys of remote polar regions is a relatively recent addition to the remote sensing capabilities serving the Cryospheric science community. The NASA/GSFC-developed airborne sensor, LVIS (Land, Vegetation, and Ice Sensor) is a wide-swath, full-waveform laser altimeter system that produces large-area topographic maps with the highest levels of accuracy and precision. Recent data collections in support of NASA's Operation IceBridge over Antarctica and Greenland have demonstrated the extraordinary mapping capability of the LVIS sensor. Areal coverage is accumulated at a rate of > 1,000 sq. km/hr with repeatability of the surface elevation measurements at the decimeter level. With this new capability come new applications, new insights, the ability to fully capture the spatial extent and variability of changes occurring in highly dynamic areas, and enhanced input into ice sheet models. One example is over 7,000 sq. km collected over the Antarctic Peninsula in just 7 hours from 40,000 ft on the NASA DC-8 aircraft. The wide swath and dense coverage enabled by the LVIS sensor results in significant overlap with legacy ICESat data permitting statistically powerful comparisons and eliminate the need for interpolation or slope corrections. Several examples of ICESat comparisons and change detection between LVIS data takes and other topographic data sets will be presented . Further, a description of the LVIS waveform vector data product and examples of advanced data products and analysis techniques with be shown. A fully-autonomous version of LVIS is now under development (LVIS-GH) for use in the Global Hawk aircraft. Long duration flights over remote areas will be possible with this sensor. Testing on the Global Hawk UAV is scheduled for the Summer of 2011. The LVIS data are freely available from the NSIDC website (http://nsidc.org/data/icebridge/) and the LVIS website (https://lvis.gsfc.nasa.gov).

  5. A Method for Rapid Determination of the Icing Limit of a Body in Terms of the Stream Conditions

    NASA Technical Reports Server (NTRS)

    Callaghan, Edmund E.; Serafini, John S.

    1953-01-01

    The effects of existing frictional heating were analyzed to determine the conditions under which ice formations on aircraft surfaces can be prevented. A method is presented for rapidly determining by means of charts the combination of-Mach number, altitude, and stream temperature which will maintain an ice-free surface in an icing cloud. The method can be applied to both subsonic and supersonic flow. The charts presented are for Mach numbers up to 1.8 and pressure altitudes from sea level to 45,000 feet.

  6. Modeling and Detection of Ice Particle Accretion in Aircraft Engine Compression Systems

    NASA Technical Reports Server (NTRS)

    May, Ryan D.; Simon, Donald L.; Guo, Ten-Huei

    2012-01-01

    The accretion of ice particles in the core of commercial aircraft engines has been an ongoing aviation safety challenge. While no accidents have resulted from this phenomenon to date, numerous engine power loss events ranging from uneventful recoveries to forced landings have been recorded. As a first step to enabling mitigation strategies during ice accretion, a detection scheme must be developed that is capable of being implemented on board modern engines. In this paper, a simple detection scheme is developed and tested using a realistic engine simulation with approximate ice accretion models based on data from a compressor design tool. These accretion models are implemented as modified Low Pressure Compressor maps and have the capability to shift engine performance based on a specified level of ice blockage. Based on results from this model, it is possible to detect the accretion of ice in the engine core by observing shifts in the typical sensed engine outputs. Results are presented in which, for a 0.1 percent false positive rate, a true positive detection rate of 98 percent is achieved.

  7. Documentation of Atmospheric Conditions During Observed Rising Aircraft Wakes

    NASA Technical Reports Server (NTRS)

    Zak, J. Allen; Rodgers, William G., Jr.

    1997-01-01

    Flight tests were conducted in the fall of 1995 off the coast of Wallops Island, Virginia in order to determine characteristics of wake vortices at flight altitudes. A NASA Wallops Flight Facility C130 aircraft equipped with smoke generators produced visible wakes at altitudes ranging from 775 to 2225 m in a variety of atmospheric conditions, orientations (head wind, cross wind), and airspeeds. Meteorological and aircraft parameters were collected continuously from a Langley Research Center OV-10A aircraft as it flew alongside and through the wake vortices at varying distances behind the C130. Meteorological data were also obtained from special balloon observations made at Wallops. Differential GPS capabilities were on each aircraft from which accurate altitude profiles were obtained. Vortices were observed to rise at distances beyond a mile behind the C130. The maximum altitude was 150 m above the C130 in a near neutral atmosphere with significant turbulence. This occurred from large vertical oscillations in the wakes. There were several cases when vortices did not descend after a very short initial period and remained near generation altitude in a variety of moderately stable atmospheres and wind shears.

  8. Mapping of ice, snow and water using aircraft-mounted LiDAR

    NASA Astrophysics Data System (ADS)

    Church, Philip; Matheson, Justin; Owens, Brett

    2016-05-01

    Neptec Technologies Corp. has developed a family of obscurant-penetrating 3D laser scanners (OPAL 2.0) that are being adapted for airborne platforms for operations in Degraded Visual Environments (DVE). The OPAL uses a scanning mechanism based on the Risley prism pair. Data acquisition rates can go as high as 200kHz for ranges within 240m and 25kHz for ranges exceeding 240m. The scan patterns are created by rotating two prisms under independent motor control producing a conical Field-Of-View (FOV). An OPAL laser scanner with 90° FOV was installed on a Navajo aircraft, looking down through an aperture in the aircraft floor. The rotation speeds of the Risley prisms were selected to optimize a uniformity of the data samples distribution on the ground. Flight patterns simulating a landing approach over snow and ice in an unprepared Arctic environment were also performed to evaluate the capability of the OPAL LiDAR to map snow and ice elevation distribution in real-time and highlight potential obstacles. Data was also collected to evaluate the detection of wires when flying over water, snow and ice. Main results and conclusions obtained from the flight data analysis are presented.

  9. Air conditioning system with supplemental ice storing and cooling capacity

    DOEpatents

    Weng, Kuo-Lianq; Weng, Kuo-Liang

    1998-01-01

    The present air conditioning system with ice storing and cooling capacity can generate and store ice in its pipe assembly or in an ice storage tank particularly equipped for the system, depending on the type of the air conditioning system. The system is characterized in particular in that ice can be produced and stored in the air conditioning system whereby the time of supplying cooled air can be effectively extended with the merit that the operation cycle of the on and off of the compressor can be prolonged, extending the operation lifespan of the compressor in one aspect. In another aspect, ice production and storage in great amount can be performed in an off-peak period of the electrical power consumption and the stored ice can be utilized in the peak period of the power consumption so as to provide supplemental cooling capacity for the compressor of the air conditioning system whereby the shift of peak and off-peak power consumption can be effected with ease. The present air conditioning system can lower the installation expense for an ice-storing air conditioning system and can also be applied to an old conventional air conditioning system.

  10. 14 CFR 125.221 - Icing conditions: Operating limitations.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... airplane that has frost, ice, or snow adhering to any propeller, windshield, stabilizing or control surface... system, or wing, except that takeoffs may be made with frost under the wing in the area of the fuel tanks... pilot may take off an airplane any time conditions are such that frost, ice, or snow may reasonably...

  11. 14 CFR 125.221 - Icing conditions: Operating limitations.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... airplane that has frost, ice, or snow adhering to any propeller, windshield, stabilizing or control surface... system, or wing, except that takeoffs may be made with frost under the wing in the area of the fuel tanks... pilot may take off an airplane any time conditions are such that frost, ice, or snow may reasonably...

  12. 14 CFR 125.221 - Icing conditions: Operating limitations.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... airplane that has frost, ice, or snow adhering to any propeller, windshield, stabilizing or control surface... system, or wing, except that takeoffs may be made with frost under the wing in the area of the fuel tanks... pilot may take off an airplane any time conditions are such that frost, ice, or snow may reasonably...

  13. 14 CFR 125.221 - Icing conditions: Operating limitations.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... airplane that has frost, ice, or snow adhering to any propeller, windshield, stabilizing or control surface... system, or wing, except that takeoffs may be made with frost under the wing in the area of the fuel tanks... pilot may take off an airplane any time conditions are such that frost, ice, or snow may reasonably...

  14. An Approach to Detect and Mitigate Ice Particle Accretion in Aircraft Engine Compression Systems

    NASA Technical Reports Server (NTRS)

    May, Ryan D.; Guo, Ten-Huei; Simon, Donald L.

    2013-01-01

    The accretion of ice in the compression system of commercial gas turbine engines operating in high ice water content conditions is a safety issue being studied by the aviation sector. While most of the research focuses on the underlying physics of ice accretion and the meteorological conditions in which accretion can occur, a systems-level perspective on the topic lends itself to potential near-term operational improvements. This work focuses on developing an accurate and reliable algorithm for detecting the accretion of ice in the low pressure compressor of a generic 40,000 lbf thrust class engine. The algorithm uses only the two shaft speed sensors and works regardless of engine age, operating condition, and power level. In a 10,000-case Monte Carlo simulation, the detection approach was found to have excellent capability at determining ice accretion from sensor noise with detection occurring when ice blocks an average of 6.8% of the low pressure compressor area. Finally, an initial study highlights a potential mitigation strategy that uses the existing engine actuators to raise the temperature in the low pressure compressor in an effort to reduce the rate at which ice accretes.

  15. An Approach to Detect and Mitigate Ice Particle Accretion in Aircraft Engine Compression Systems

    NASA Technical Reports Server (NTRS)

    May, Ryan D.; Guo, Ten-Huei; Simon, Donald L.

    2013-01-01

    The accretion of ice in the compression system of commercial gas turbine engines operating in high ice water content conditions is a safety issue being studied by the aviation sector. While most of the research focuses on the underlying physics of ice accretion and the meteorological conditions in which accretion can occur, a systems-level perspective on the topic lends itself to potential near-term operational improvements. This work focuses on developing an accurate and reliable algorithm for detecting the accretion of ice in the low pressure compressor of a generic 40,000 lbf thrust class engine. The algorithm uses only the two shaft speed sensors and works regardless of engine age, operating condition, and power level. In a 10,000-case Monte Carlo simulation, the detection approach was found to have excellent capability at determining ice accretion from sensor noise with detection occurring when ice blocks an average of 6.8 percent of the low pressure compressor area. Finally, an initial study highlights a potential mitigation strategy that uses the existing engine actuators to raise the temperature in the low pressure compressor in an effort to reduce the rate at which ice accretes.

  16. Basal hydraulic conditions of Ice Stream B

    NASA Technical Reports Server (NTRS)

    Engelhardt, Hermann; Kamb, Barclay

    1993-01-01

    Fifteen boreholes have been drilled to the base of Ice Stream B in the vicinity of UpB Camp. The boreholes are spread over an area of about 500 x 1000 m. Several till cores were retrieved from the bottom of the 1000-m-deep holes. Laboratory tests using a simple shear box revealed a yield strength of basal till of 2 kPa. This agrees well with in-situ measurements using a shear vane. Since the average basal shear stress of Ice Stream B with a surface slope of 0.1 degree is about 20 kPa, the ice stream cannot be supported by till that weak. Additional support for this conclusion comes from the basal water pressure that has been measured in all boreholes as soon as the hot water drill reached bottom. In several boreholes, the water pressure has been continuously monitored; in two of them, over several years. The water pressure varies but stays within 1 bar of flotation where ice overburden pressure and water pressure are equal. The ratio of water and overburden pressure lies between 0.986 and 1.002. This is an extremely high value as compared to other fast-moving ice masses; e.g., Variegated Glacier in surge has a ratio of 0.8, and Columbia Glacier - a fast-moving tidewater glacier - has a ratio of 0.9. It implies that water flow under the glacier occurs in a thin film and not in conduits that would drain away water too rapidly. It also implies that basal sliding must be very effective. Water flow under the glacier was measured in a salt-injection experiment where a salt pulse was released at the bottom of a borehole while 60 m down-glacier, the electrical resistance was measured between two other boreholes. A flow velocity of 7 mm/s was obtained.

  17. Comparison of Profiling Microwave Radiometer, Aircraft, and Radiosonde Measurements From the Alliance Icing Research Study (AIRS)

    NASA Technical Reports Server (NTRS)

    Reehorst, Andrew L.

    2001-01-01

    Measurements from a profiling microwave radiometer are compared to measurements from a research aircraft and radiosondes. Data compared is temperature, water vapor, and liquid water profiles. Data was gathered at the Alliance Icing Research Study (AIRS) at Mirabel Airport outside Montreal, Canada during December 1999 and January 2000. All radiometer measurements were found to lose accuracy when the radome was wet. When the radome was not wetted, the radiometer was seen to indicate an inverted distribution of liquid water within a cloud. When the radiometer measurements were made at 15 deg. instead of the standard zenith, the measurements were less accurate.

  18. Numerical investigations of future ice conditions in the Baltic Sea.

    PubMed

    Haapala, J; Meier, H E; Rinne, J

    2001-08-01

    Global climate changes is expected to have an effect on the physical and ecological characteristics of the Baltic Sea. Estimates of future climate on the regional scale can be obtained by using either statistical or dynamical downscaling methods of global AOGCM scenario results. In this paper, we use 2 different coupled ice-ocean models of the Baltic Sea to simulate present and future ice conditions around 100 years from present. Two 10-year time slice experiments have been performed using the results of atmospheric climate model simulations as forcing, one representing pre-industrial climate conditions (control simulation), and the other global warming with a 150% increase in CO2 greenhouse gas concentration (scenario simulation). Present-day climatological ice conditions and interannual variability are realistically reproduced by the models. The simulated range of the maximum annual ice extent in the Baltic in both models together is 180 to 420 x 10(3) km2 in the control simulation and 45 to 270 x 10(3) km2 in the scenario simulation. The range of the maximum annual ice thickness is from 32 to 96 cm and from 11 to 60 cm in the control and scenario simulations, respectively. In contrast to earlier estimates, sea ice is still formed every winter in the Northern Bothnian Bay and in the most Eastern parts of the Gulf of Finland. Overall, the simulated changes of quantities such as ice extent and ice thickness, as well as their interannual variations are relatively similar in both models, which is remarkable, because the 2 coupled ice-ocean model systems have been developed independently. This increases the reliability of future projections of ice conditions in the Baltic Sea. PMID:11697256

  19. Creep of water ices at planetary conditions: A compilation

    USGS Publications Warehouse

    Durham, W.B.; Kirby, S.H.; Stern, L.A.

    1997-01-01

    Many constitutive laws for the flow of ice have been published since the advent of the Voyager explorations of the outer solar system. Conflicting data have occasionally come from different laboratories, and refinement of experimental techniques has led to the publication of laws that supersede earlier ones. In addition, there are unpublished data from ongoing research that also amend the constitutive laws. Here we compile the most current laboratory-derived flow laws for water ice phases I, II, III, V, and VI, and ice I mixtures with hard particulates. The rheology of interest is mainly that of steady state, and the conditions reviewed are the pressures and temperatures applicable to the surfaces and interiors of icy moons of the outer solar system. Advances in grain-size-dependent creep in ices I and II as well as in phase transformations and metastability under differential stress are also included in this compilation. At laboratory strain rates the several ice polymorphs are rheologically distinct in terms of their stress, temperature, and pressure dependencies but, with the exception of ice III, have fairly similar strengths. Hard particulates strengthen ice I significantly only at high particulate volume fractions. Ice III has the potential for significantly affecting mantle dynamics because it is much weaker than the other polymorphs and its region of stability, which may extend metastably well into what is nominally the ice II field, is located near likely geotherms of large icy moons. Copyright 1997 by the American Geophysical Union.

  20. 14 CFR 91.527 - Operating in icing conditions.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... conditions. (a) No pilot may take off an airplane that has frost, ice, or snow adhering to any propeller... of climb, or flight attitude instrument system or wing, except that takeoffs may be made with...

  1. 14 CFR 91.527 - Operating in icing conditions.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... conditions. (a) No pilot may take off an airplane that has frost, ice, or snow adhering to any propeller... of climb, or flight attitude instrument system or wing, except that takeoffs may be made with...

  2. 14 CFR 91.527 - Operating in icing conditions.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... conditions. (a) No pilot may take off an airplane that has frost, ice, or snow adhering to any propeller... of climb, or flight attitude instrument system or wing, except that takeoffs may be made with...

  3. 14 CFR 91.527 - Operating in icing conditions.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... conditions. (a) No pilot may take off an airplane that has frost, ice, or snow adhering to any propeller... of climb, or flight attitude instrument system or wing, except that takeoffs may be made with...

  4. Ice Particle Growth Rates Under Upper Troposphere Conditions

    NASA Technical Reports Server (NTRS)

    Peterson, Harold; Bailey, Matthew; Hallett, John

    2010-01-01

    Atmospheric conditions for growth of ice crystals (temperature and ice supersaturation) are often not well constrained and it is necessary to simulate such conditions in the laboratory to investigate such growth under well controlled conditions over many hours. The growth of ice crystals from the vapour in both prism and basal planes was observed at temperatures of -60 C and -70 C under ice supersaturation up to 100% (200% relative humidity) at pressures derived from the standard atmosphere in a static diffusion chamber. Crystals grew outward from a vertical glass filament, thickening in the basal plane by addition of macroscopic layers greater than 2 m, leading to growth in the prism plane by passing of successive layers conveniently viewed by time lapse video.

  5. Ice Crystal Growth Rates Under Upper Troposphere Conditions

    NASA Technical Reports Server (NTRS)

    Peterson, Harold S.; Bailey, Matthew; Hallett, John

    2010-01-01

    Atmospheric conditions for growth of ice crystals (temperature and ice supersaturation) are often not well constrained and it is necessary to simulate such conditions in the laboratory to investigate such growth under well controlled conditions over many hours. The growth of ice crystals from the vapour in both prism and basal planes was observed at temperatures of -60 C and -70 C under ice supersaturation up to 100% (200% relative humidity) at pressures derived from the standard atmosphere in a static diffusion chamber. Crystals grew outward from a vertical glass filament, thickening in the basal plane by addition of macroscopic layers greater than 2 m, leading to growth in the prism plane by passing of successive layers conveniently viewed by time lapse video.

  6. Ice Particle Growth Under Conditions of the Upper Troposphere

    NASA Technical Reports Server (NTRS)

    Peterson, Harold S.; Bailey, Matthew; Hallett, John

    2010-01-01

    Atmospheric conditions for growth of ice crystals (temperature and ice supersaturation) are often not well constrained and it is necessary to simulate such conditions in the laboratory to investigate such growth under well controlled conditions over many hours. The growth of ice crystals from the vapour in both prism and basal planes was observed at temperatures of -60 C and -70 C under ice supersaturation up to 100% (200% relative humidity) at pressures derived from the standard atmosphere in a static diffusion chamber. Crystals grew outward from a vertical glass filament, thickening in the basal plane by addition of macroscopic layers greater than 2 microns, leading to growth in the prism plane by passing of successive layers conveniently viewed by time lapse video.

  7. Heat generation in aircraft tires under free rolling conditions

    NASA Technical Reports Server (NTRS)

    Clark, S. K.; Dodge, R. N.

    1982-01-01

    A method was developed for calculating the internal temperature distribution in an aircraft tire while free rolling under load. The method uses an approximate stress analysis of each point in the tire as it rolls through the contact patch, and from this stress change the mechanical work done on each volume element may be obtained and converted into a heat release rate through a knowledge of material characteristics. The tire cross-section is then considered as a body with internal heat generation, and the diffusion equation is solved numerically with appropriate boundary conditions of the wheel and runway surface. Comparison with data obtained with buried thermocouples in tires shows good agreement.

  8. Additional Results of Glaze Icing Scaling in SLD Conditions

    NASA Technical Reports Server (NTRS)

    Tsao, Jen-Ching

    2016-01-01

    New guidance of acceptable means of compliance with the super-cooled large drops (SLD) conditions has been issued by the U.S. Department of Transportation's Federal Aviation Administration (FAA) in its Advisory Circular AC 25-28 in November 2014. The Part 25, Appendix O is developed to define a representative icing environment for super-cooled large drops. Super-cooled large drops, which include freezing drizzle and freezing rain conditions, are not included in Appendix C. This paper reports results from recent glaze icing scaling tests conducted in NASA Glenn Icing Research Tunnel (IRT) to evaluate how well the scaling methods recommended for Appendix C conditions might apply to SLD conditions. The models were straight NACA 0012 wing sections. The reference model had a chord of 72 in. and the scale model had a chord of 21 in. Reference tests were run with airspeeds of 100 and 130.3 kn and with MVD's of 85 and 170 micron. Two scaling methods were considered. One was based on the modified Ruff method with scale velocity found by matching the Weber number WeL. The other was proposed and developed by Feo specifically for strong glaze icing conditions, in which the scale liquid water content and velocity were found by matching reference and scale values of the nondimensional water-film thickness expression and the film Weber number Wef. All tests were conducted at 0 deg AOA. Results will be presented for stagnation freezing fractions of 0.2 and 0.3. For nondimensional reference and scale ice shape comparison, a new post-scanning ice shape digitization procedure was developed for extracting 2-D ice shape profiles at any selected span-wise location from the high fidelity 3-D scanned ice shapes obtained in the IRT.

  9. Spatial heterogeneity of ocean surface boundary conditions under sea ice

    NASA Astrophysics Data System (ADS)

    Barthélemy, Antoine; Fichefet, Thierry; Goosse, Hugues

    2016-06-01

    The high heterogeneity of sea ice properties implies that its effects on the ocean are spatially variable at horizontal scales as small as a few meters. Previous studies have shown that taking this variability into account in models could be required to simulate adequately mixed layer processes and the upper ocean temperature and salinity structures. Although many advanced sea ice models include a subgrid-scale ice thickness distribution, potentially providing heterogeneous surface boundary conditions, the information is lost in the coupling with a unique ocean grid cell underneath. The present paper provides a thorough examination of boundary conditions at the ocean surface in the NEMO-LIM model, which can be used as a guideline for studies implementing subgrid-scale ocean vertical mixing schemes. Freshwater, salt, solar heat and non-solar heat fluxes are examined, as well as the norm of the surface stress. All of the thermohaline fluxes vary considerably between the open water and ice fractions of grid cells. To a lesser extent, this is also the case for the surface stress. Moreover, the salt fluxes in both hemispheres and the solar heat fluxes in the Arctic show a dependence on the ice thickness category, with more intense fluxes for thinner ice, which promotes further subgrid-scale heterogeneity. Our analysis also points out biases in the simulated open water fraction and in the ice thickness distribution, which should be investigated in more details in order to ensure that the latter is used to the best advantage.

  10. EOS Aqua AMSR-E Arctic Sea-Ice Validation Program: Arctic2006 Aircraft Campaign Flight Report

    NASA Technical Reports Server (NTRS)

    Cavalieri, D. J.; Markus, T.

    2006-01-01

    In March 2006, a coordinated Arctic sea-ice validation field campaign using the NASA Wallops P-3B aircraft was successfully completed. This campaign was the second Alaskan Arctic field campaign for validating the Earth Observing System (EOS) Aqua Advanced Microwave Scanning Radiometer (AMSR-E) sea-ice products. The first campaign was completed in March 2003. The AMSR-E, designed and built by the Japanese Space Agency for NASA, was launched May 4, 2002 on the EOS Aqua spacecraft. The AMSR-E sea-ice products to be validated include sea-ice concentration, sea-ice temperature, and snow depth on sea ice. The focus of this campaign was on the validation of snow depth on sea ice and sea-ice temperature. This flight report describes the suite of instruments flown on the P-3, the objectives of each of the six flights, the Arctic regions overflown, and the coordination among satellite, aircraft, and surface-based measurements.

  11. 14 CFR 121.341 - Equipment for operations in icing conditions.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... other parts of the airplane where ice formation will adversely affect the safety of the airplane. (b) No... icing conditions; (2) Under VFR into known light or moderate icing conditions; unless the airplane...

  12. 14 CFR 121.341 - Equipment for operations in icing conditions.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... other parts of the airplane where ice formation will adversely affect the safety of the airplane. (b) No... icing conditions; (2) Under VFR into known light or moderate icing conditions; unless the airplane...

  13. 14 CFR 121.341 - Equipment for operations in icing conditions.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... other parts of the airplane where ice formation will adversely affect the safety of the airplane. (b) No... icing conditions; (2) Under VFR into known light or moderate icing conditions; unless the airplane...

  14. The Calculation of the Heat Required for Wing Thermal Ice Prevention in Specified Icing Conditions

    NASA Technical Reports Server (NTRS)

    Bergrun, Norman R.; Jukoff, David; Schlaff, Bernard A.; Neel, Carr B., Jr.

    1947-01-01

    Flight tests were made in natural icing conditions with two 8-ft-chord heated airfoils of different sections. Measurements of meteorological variables conducive to ice formation were made simultaneously with the procurement of airfoil thermal data. The extent of knowledge on the meteorology of icing, the impingement of water drops on airfoil surfaces, and the processes of heat transfer and evaporation from a wetted airfoil surface have been increased to a point where the design of heated wings on a fundamental, wet-air basis now can be undertaken with reasonable certainty.

  15. Surface micro-grooves for near-wall exergy and flow control: application to aircraft intake de-icing

    NASA Astrophysics Data System (ADS)

    Naterer, G. F.; Glockner, P. S.; Thiele, D.; Chomokovski, S.; Venn, G.; Richardson, G.

    2005-03-01

    This paper develops a new surface micro-profiling technique for reducing exergy losses and controlling near-wall flow processes, particularly for anti-icing of a helicopter surface. Fabrication of embedded surface microchannels entails surface etching with KOH and XeF2 gas, so that the interspersed microchannels can be assembled into a surface layer of silicon. Testing of the micro-profiled surfaces is performed with particle image velocimetry in a water tunnel. Experimental data indicate that converging open microchannels lead to certain differences of flow patterns on the downstream side of an engine cooling bay. Furthermore, exergy losses for external flow past the parallel embedded microchannels are shown to be lower than previous benchmark results without microchannels. Analytical results are presented for these losses of available energy and exergy destruction. Reduced drag of slip-flow conditions within each microchannel offsets the added friction irreversibility of larger surface area. By altering the near-wall flow patterns, it is anticipated that embedded surface microchannels can provide a useful new approach for dealing with flow-related problems of aircraft icing.

  16. Aircraft Landing Gear, Ice and Rain Control Systems (Course Outline), Aviation Mechanics 3 (Air Frame):9067.02.

    ERIC Educational Resources Information Center

    Dade County Public Schools, Miami, FL.

    This document presents an outline for a 135-hour course designed to familiarize the student with operation, inspection, troubleshooting, and repair of aircraft landing gear, ice and rain control systems. It is designed to help the trainee master the knowledge and skills necessary to become an aviation airframe mechanic. The aviation airframe…

  17. 76 FR 55293 - Special Conditions: Diamond Aircraft Industries, Model DA-40NG; Electronic Engine Control (EEC...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-07

    ... TRANSPORTATION Federal Aviation Administration 14 CFR Part 23 Special Conditions: Diamond Aircraft Industries... Diamond Aircraft Industries (DAI), model DA-40NG airplane. This airplane will have a novel or unusual... stamped and returned to the commenter. Background On May 11, 2010 Diamond Aircraft Industry GmbH...

  18. Ice Nuclei in Mid-Latitude Cirrus: Preliminary Results from a New Counterflow Virtual Impactor (CVI) Aircraft Inlet

    NASA Astrophysics Data System (ADS)

    Froyd, K. D.; Cziczo, D. J.; Murphy, D. M.; Kulkarni, G.; Lawson, P.

    2011-12-01

    Cirrus cloud properties are strongly governed by the mechanism of ice particle formation and by the number and effectiveness of ambient ice nuclei. Airborne measurements of ice nuclei reveal new nucleation mechanisms, provide constraints on microphysical models, and guide laboratory investigations. For over two decades the Counterflow Virtual Impactor (CVI) inlet has remained the prevailing approach for sampling cloud particles to measure ice nuclei from an aircraft platform. However, traditional CVI inlets have fundamental limitations when operating on high speed aircraft, where only a small fraction of ambient cloud particles are typically sampled. A novel 'folded' CVI was constructed and deployed during the NASA MACPEX 2011 campaign. The flow design of this inlet effectively doubles the CVI length and thereby increases the size range of captured cirrus particles. Additional design elements such as an internal vortex flow, a neon carrier gas, and an infrared laser further improve the capture and evaporation of ice crystals. Preliminary results of ice nuclei composition measured by the PALMS single-particle mass spectrometer are presented from the MACPEX campaign. Examples of ice nuclei from mid-latitude cirrus are shown, including mineral dust, organic-rich aerosol with amine and diacid components, and lead-containing aerosol.

  19. A Preliminary Study of Ice-Accretion Scaling for SLD Conditions

    NASA Technical Reports Server (NTRS)

    Anderson, David N.

    2003-01-01

    Proposed changes to aircraft icing certification rules are being considered by European, Canadian, and American regulatory agencies to include operation in super-cooled large droplet conditions (SLD). This paper reports results of an experimental study in the NASA Glenn Icing Research Tunnel (IRT) to evaluate how well scaling methods developed for Appendix C conditions might apply to SLD conditions. Until now, scaling studies have been confined to the FAA FAR-25 Appendix C envelope of atmospheric cloud conditions. Tests were made in which it was attempted to scale to a droplet MVD of 50 microns from clouds having droplet MVDs of 175, 120, 100, and 70 microns. Scaling was based on the Ruff method with scale velocities found either by maintaining constant Weber number or by using the average of the velocities obtained by maintaining constant Weber number and constant Reynolds number. Models were unswept NACA 0012 wing sections. The reference model had a chord of 91.4 cm. Scale models had chords of 91.4, 80.0, and 53.3 cm. Tests were conducted with reference airspeeds of 100 and 150 kt (52 and 77 m/s) and with freezing fractions of 1.0, 0.6, and 0.3. It was demonstrated that the scaled 50-micron cloud simulated well the non-dimensional ice shapes accreted in clouds with MVD's of 120 microns or less.

  20. Mesoscopic surface roughness of ice crystals pervasive across a wide range of ice crystal conditions

    NASA Astrophysics Data System (ADS)

    Magee, N. B.; Miller, A.; Amaral, M.; Cumiskey, A.

    2014-11-01

    Here we show high-magnification images of hexagonal ice crystals acquired by environmental scanning electron microscopy (ESEM). Most ice crystals were grown and sublimated in the water vapor environment of an FEI-Quanta-200 ESEM, but crystals grown in a laboratory diffusion chamber were also transferred intact and imaged via ESEM. All of these images display prominent mesoscopic topography including linear striations, ridges, islands, steps, peaks, pits, and crevasses; the roughness is not observed to be confined to prism facets. The observations represent the most highly magnified images of ice surfaces yet reported and expand the range of conditions in which rough surface features are known to be conspicuous. Microscale surface topography is seen to be ubiquitously present at temperatures ranging from -10 °C to -40 °C, in supersaturated and subsaturated conditions, on all crystal facets, and irrespective of substrate. Despite the constant presence of surface roughness, the patterns of roughness are observed to be dramatically different between growing and sublimating crystals, and transferred crystals also display qualitatively different patterns of roughness. Crystals are also demonstrated to sometimes exhibit inhibited growth in moderately supersaturated conditions following exposure to near-equilibrium conditions, a phenomenon interpreted as evidence of 2-D nucleation. New knowledge about the characteristics of these features could affect the fundamental understanding of ice surfaces and their physical parameterization in the context of satellite retrievals and cloud modeling. Links to supplemental videos of ice growth and sublimation are provided.

  1. Mesoscopic surface roughness of ice crystals pervasive across a wide range of ice crystal conditions

    NASA Astrophysics Data System (ADS)

    Magee, N. B.; Miller, A.; Amaral, M.; Cumiskey, A.

    2014-03-01

    Here we show high-magnification images of hexagonal ice crystals acquired by Environmental Scanning Electron Microscopy (ESEM). Most ice crystals were grown and sublimated in the water vapor environment of an FEI-Quanta-200 ESEM, but crystals grown in a laboratory diffusion chamber were also transferred intact and imaged via ESEM. All of these images display prominent mesoscopic topography including linear striations, ridges, islands, steps, peaks, pits, and crevasses; the roughness is not observed to be confined to prism facets. The observations represent the most highly magnified images of ice surfaces yet reported and expand the range of conditions where the rough surface features are known to be conspicuous. Microscale surface topography is seen to be ubiquitously present at temperatures ranging from -10 °C to -40 °C, at super-saturated and sub-saturated conditions, on all crystal facets, and irrespective of substrate. Despite the constant presence of surface roughness, the patterns of roughness are observed to be dramatically different between growing and sublimating crystals, and transferred crystals also display qualitatively different patterns of roughness. Crystals are also demonstrated to sometimes exhibit inhibited growth in moderately supersaturated conditions following exposure to near-equilibrium conditions, a phenomena interpreted as evidence of 2-D nucleation. New knowledge of the characteristics of these features could affect the fundamental understanding of ice surfaces and their physical parameterization in the context of satellite retrievals and cloud modeling. Links to Supplement videos of ice growth and sublimation are provided.

  2. The examination of a downslope warming wind event over the Larsen Ice Shelf in Antarctica through modeling and aircraft observations.

    NASA Astrophysics Data System (ADS)

    Grosvenor, Daniel; Choularton, Thomas; King, John; Lachlan-Cope, Thomas

    2010-05-01

    likely to be negated by latent heat losses from ice ablation. The main cause of any ice melting was likely to be due to shortwave radiation input. However, the warming from the jets is still likely to be important by acting as an on/off control for melting by keeping air temperatures above zero. In addition, the dryness of the winds is likely to prevent cloud cover and thus maximize exposure of the ice shelf to solar energy. This case study has been simulated using the WRF mesoscale model. The model reproduces the strong downslope winds seen by the aircraft with good matches of wind speed and temperature profiles through the wind jets. The modeling agrees with the results of the aircraft study in suggesting that solar radiation input is likely to provide the largest amount of energy for melting of the ice surface. The simulation also provides insight into the physics of the downslope winds. They are found to be driven by descent of air from high above the mountain caused by breaking mountain waves. This is a mechanism that is different from that often perceived to occur in the region, whereby air from below the mountain crest rises over the obstacle and descends on the lee side. The case is also characterized by a large degree of upstream blocking, a situation in which the previous literature has tended to assume such warming winds would not occur for this region. In fact, theoretical work suggests that the blocking may play a necessary role in producing the windstorm in this case. The production of warming on the east side of the Peninsula in blocked regimes is important as it would mean that it occurs at lower upstream wind speeds than previously thought. The possible consequence of this is that the suggested increase in the frequency of warming events over the past 50 years might not be justified by consideration of the observed westerly wind speed increases alone, but that it may also be influenced by other factors, such as wind direction or the stability conditions

  3. Mixtures of planetary ices at extreme conditions.

    PubMed

    Lee, Mal-Soon; Scandolo, Sandro

    2011-02-08

    The interiors of Neptune and Uranus are believed to be primarily composed of a fluid mixture of methane and water. The mixture is subjected to pressures up to several hundred gigapascal, causing the ionization of water. Laboratory and simulation studies so far have focused on the properties of the individual components. Here we show, using first-principle molecular dynamic simulations, that the properties of the mixed fluid are qualitatively different with respect to those of its components at the same conditions. We observe a pressure-induced softening of the methane-water intermolecular repulsion that points to an enhancement of mixing under extreme conditions. Ionized water causes the progressive ionization of methane and the mixture becomes electronically conductive at milder conditions than pure water, indicating that the planetary magnetic field of Uranus and Neptune may originate at shallower depths than currently assumed.

  4. Mixtures of planetary ices at extreme conditions.

    PubMed

    Lee, Mal-Soon; Scandolo, Sandro

    2011-01-01

    The interiors of Neptune and Uranus are believed to be primarily composed of a fluid mixture of methane and water. The mixture is subjected to pressures up to several hundred gigapascal, causing the ionization of water. Laboratory and simulation studies so far have focused on the properties of the individual components. Here we show, using first-principle molecular dynamic simulations, that the properties of the mixed fluid are qualitatively different with respect to those of its components at the same conditions. We observe a pressure-induced softening of the methane-water intermolecular repulsion that points to an enhancement of mixing under extreme conditions. Ionized water causes the progressive ionization of methane and the mixture becomes electronically conductive at milder conditions than pure water, indicating that the planetary magnetic field of Uranus and Neptune may originate at shallower depths than currently assumed. PMID:21304514

  5. Additional Results of Ice-Accretion Scaling at SLD Conditions

    NASA Technical Reports Server (NTRS)

    Bond, Thomas H. (Technical Monitor); Anderson, David N.; Tsao, Jen-Ching

    2005-01-01

    To determine scale velocity an additional similarity parameter is needed to supplement the Ruff scaling method. A Weber number based on water droplet MVD has been included in several studies because the effect of droplet splashing on ice accretion was believed to be important, particularly for SLD conditions. In the present study, ice shapes recorded at Appendix-C conditions and recent results at SLD conditions are reviewed to show that droplet diameter cannot be important to main ice shape, and for low airspeeds splashing does not appear to affect SLD ice shapes. Evidence is presented to show that while a supplementary similarity parameter probably has the form of a Weber number, it must be based on a length proportional to model size rather than MVD. Scaling comparisons were made between SLD reference conditions and Appendix-C scale conditions using this Weber number. Scale-to-reference model size ratios were 1:1.7 and 1:3.4. The reference tests used a 91-cm-chord NACA 0012 model with a velocity of approximately 50 m/s and an MVD of 160 m. Freezing fractions of 0.3, 0.4, and 0.5 were included in the study.

  6. Effects of atmospheric conditions on ice nucleation activity of Pseudomonas

    NASA Astrophysics Data System (ADS)

    Attard, E.; Yang, H.; Delort, A.-M.; Amato, P.; Pöschl, U.; Glaux, C.; Koop, T.; Morris, C. E.

    2012-11-01

    Although ice nuclei from bacterial origin are known to be efficient at the highest temperatures known for ice catalysts, quantitative data are still needed to assess their role in cloud processes. Here we studied the effects of three typical cloud conditions (i) acidic pH (ii) NO2 and O3 exposure and (iii) UV-A exposure on the ice nucleation activity (INA) of four Pseudomonas strains. Three of the Pseudomonas syringae strains were isolated from cloud water and the phyllosphere and Pseudomonas fluorescens strain CGina-01 was isolated from Antarctic glacier ice melt. Among the three conditions tested, acidic pH caused the most significant effects on INA likely due to denaturation of the ice nucleation protein complex. Exposure to NO2 and O3 gases had no significant or only weak effects on the INA of two P. syringae strains whereas the INA of P. fluorescens CGina-01 was significantly affected. The INA of the third P. syringae strain showed variable responses to NO2 and O3 exposure. These differences in the INA of different Pseudomonas suggest that the response to atmospheric conditions could be strain-specific. After UV-A exposure, a substantial loss of viability of all four strains was observed whereas their INA decreased only slightly. This corroborates the notion that under certain conditions dead bacterial cells can maintain their INA. Overall, the negative effects of the three environmental factors on INA were more significant at the warmer temperatures. Our results suggest that in clouds where temperatures are near 0 °C, the importance of bacterial ice nucleation in precipitation processes could be reduced by some environmental factors.

  7. Effects of atmospheric conditions on ice nucleation activity of Pseudomonas

    NASA Astrophysics Data System (ADS)

    Attard, E.; Yang, H.; Delort, A.-M.; Amato, P.; Pöschl, U.; Glaux, C.; Koop, T.; Morris, C. E.

    2012-04-01

    Although ice nuclei from bacterial origin are known to be efficient at the highest temperatures known for ice catalysts, quantitative data are still needed to assess their role in cloud processes. Here we studied the effects of three typical cloud conditions (i) acidic pH (ii) NO2 and O3 exposure and (iii) UV-A exposure on the ice nucleation activity (INA) of four Pseudomonas strains. Three of the Pseudomonas syringae strains were isolated from cloud water and the phyllosphere and Pseudomonas fluorescens strain CGina-01 was isolated from Antarctic glacier ice melt. Among the three conditions tested, acidic pH caused the most significant effects on INA likely due to denaturation of the ice nucleation protein complex. Exposure to NO2 and O3 gases had no significant or only weak effects on the INA of two P. syringae strains whereas the INA of P. fluorescens CGina-01 was significantly affected. The INA of the third P. syringae strain showed variable responses to NO2 and O3 exposure. These differences in the INA of different Pseudomonas suggest that the response to atmospheric conditions could be strain-specific. After UV-A exposure, a substantial loss of viability of all four strains was observed whereas their INA decreased only slightly. This corroborates the notion that under certain conditions dead bacterial cells can maintain their INA. Overall, the negative effects of the three environmental factors on INA were more significant at the warmer temperatures. Our results suggest that in clouds where temperatures are near 0 °C, the importance of bacterial ice nucleation in precipitation processes could be reduced by some environmental factors.

  8. Relationship between ice island movement and weather conditions

    SciTech Connect

    Yan, M.H.

    1986-09-01

    The object of this study is to find the relationship between ice island movement and synoptic weather conditions by using daily ice island position information and surface pressure maps. Trajectory analysis of an ice island for one year shows three types of movement episodes: (1) large movement in the southwest direction; (2) medium movement in two sequentially opposite directions; and (3) small random movement. Surface pressure maps show that an off-shore geostrophic wind component is a necessary pre-condition for the large and medium movements in the southwest direction. A high pressure system located near the North Pole then causes the movement in the southwest direction, whereas a low pressure system located near the North Pole causes the movement in the northeast direction. Results show that the speed ratios between the ice island and the geostrophic wind range from 1.0% to 1.5% for the large movement and 0.1% to 1.0% for the medium movement; the average angle ranges from 20 to 26/sup 0/ counterclockwise from the geostrophic wind direction to the ice island movement direction. A force balance shows that, for an equilibrium drifting state, a residual force must be included. 60 refs., 55 figs., 7 tabs.

  9. Quasi-Liquid Layer Formation on Ice under Stratospheric Conditions

    NASA Technical Reports Server (NTRS)

    McNeill, V. Faye; Loerting, Thomas; Trout, Bernhardt L.; Molina, Luisa T.; Molina, Mario J.

    2004-01-01

    Characterization of the interaction of hydrogen chloride (HCl) with ice is essential to understanding at a molecular level the processes responsible for ozone depletion involving polar stratospheric cloud (PSC) particles. To explain the catalytic role PSC particle surfaces play during chlorine activation, we proposed previously that HCl induces the formation of a disordered region on the ice surface, a quasi-liquid layer (QLL), at stratospheric conditions. The QLL is known to exist in pure ice crystals at temperatures near the melting point, but its existence at stratospheric temperatures (-85 C to -70 C) had not been reported yet. We studied the interaction of HCl with ice under stratospheric conditions using the complementary approach of a) ellipsometry to directly monitor the ice surface, using chemical ionization mass spectrometry (CIMS) to monitor the gas phase species present in the ellipsometry experiments, and b) flow-tube experiments with CIMS detection. Here we show that trace amounts of HCl induce QLL formation at stratospheric temperatures, and that the QLL enhances the chlorine-activation reaction of HCl with chlorine nitrate (ClONO2), and also enhances acetic acid (CH3COOH) adsorption.

  10. LWC and Temperature Effects on Ice Accretion Formation on Swept Wings at Glaze Ice Conditions

    NASA Technical Reports Server (NTRS)

    Vargas, Mario; Reshotko, Eli

    2000-01-01

    An experiment was conducted to study the effect of liquid water content and temperature on the critical distance in ice accretion formation on swept wings at glaze ice conditions. The critical distance is defined as the distance from the attachment line to tile beginning of the zone where roughness elements develop into glaze ice feathers. A baseline case of 150 mph, 25 F, 0.75 g/cu m. Cloud Liquid Water Content (LWC) and 20 micrometers in Water Droplet Median Volume Diameter (MVD) was chosen. Icing runs were performed on a NACA 0012 swept wing tip at 150 mph and MVD of 20 micrometers for liquid water contents of 0.5 g/cu m, 0.75 g/cu m, and 1.0 g/cu m, and for total temperatures of 20 F, 25 F and 30 F. At each tunnel condition, the sweep angle was changed from 0 deg to 45 deg in 5 deg increments. Casting data, ice shape tracings, and close-up photographic data were obtained. The results showed that decreasing the LWC to 0.5 g/cu m decreases the value of the critical distance at a given sweep angle compared to the baseline case, and starts the formation of complete scallops at 30 sweep angle. Increasing the LWC to 1.0 g/cu m increases the value of the critical distance compared to the baseline case, the critical distance remains always above 0 millimeters and complete scallops are not formed. Decreasing the total temperature to 20 F decreases the critical distance with respect to the baseline case and formation of complete scallops begins at 25 deg sweep angle. When the total temperature is increased to 30 F, bumps covered with roughness elements appear on the ice accretion at 25 deg and 30 deg sweep angles, large ice structures appear at 35 deg and 40 deg sweep angles, and complete scallops are formed at 45 deg sweep angle.

  11. Icing simulation: A survey of computer models and experimental facilities

    NASA Technical Reports Server (NTRS)

    Potapczuk, M. G.; Reinmann, J. J.

    1991-01-01

    A survey of the current methods for simulation of the response of an aircraft or aircraft subsystem to an icing encounter is presented. The topics discussed include a computer code modeling of aircraft icing and performance degradation, an evaluation of experimental facility simulation capabilities, and ice protection system evaluation tests in simulated icing conditions. Current research focussed on upgrading simulation fidelity of both experimental and computational methods is discussed. The need for increased understanding of the physical processes governing ice accretion, ice shedding, and iced airfoil aerodynamics is examined.

  12. 14 CFR 125.221 - Icing conditions: Operating limitations.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 74 FR 62696, Dec. 1, 2009. (a) No pilot may take off an airplane that has frost, ice, or snow... follow conditions: (1) Takeoffs may be made with frost adhering to the wings, or stabilizing or control surfaces, if the frost has been polished to make it smooth. (2) Takeoffs may be made with frost under...

  13. Smart aircraft fastener evaluation (SAFE) system: a condition-based corrosion detection system for aging aircraft

    NASA Astrophysics Data System (ADS)

    Schoess, Jeffrey N.; Seifert, Greg; Paul, Clare A.

    1996-05-01

    The smart aircraft fastener evaluation (SAFE) system is an advanced structural health monitoring effort to detect and characterize corrosion in hidden and inaccessible locations of aircraft structures. Hidden corrosion is the number one logistics problem for the U.S. Air Force, with an estimated maintenance cost of $700M per year in 1990 dollars. The SAFE system incorporates a solid-state electrochemical microsensor and smart sensor electronics in the body of a Hi-Lok aircraft fastener to process and autonomously report corrosion status to aircraft maintenance personnel. The long-term payoff for using SAFE technology will be in predictive maintenance for aging aircraft and rotorcraft systems, fugitive emissions applications such as control valves, chemical pipeline vessels, and industrial boilers. Predictive maintenance capability, service, and repair will replace the current practice of scheduled maintenance to substantially reduce operational costs. A summary of the SAFE concept, laboratory test results, and future field test plans is presented.

  14. Crystallization of CO2 ice at astronomical conditions

    NASA Astrophysics Data System (ADS)

    Escribano, R. M.; Munoz-Caro, G.; Cruz-Diaz, G.; Mate, B.; Rodriguez-Lazcano, Y.

    2013-12-01

    Carbon dioxide is, after water and comparable to carbon monoxide, one of the most abundant frozen molecular species observed in the lines of sight towards many astrophysical media. We present here an experimental and theoretical investigation on carbon dioxide ices, generated in the lab in a range of temperature, density, amorphicity, and growing conditions (1), and simulated via high level theoretical calculations. Amorphous CO2 ice was generated at CAB by deposition onto a CsI substrate at 8 K under ultrahigh vacuum conditions in the 10-11 mbar range. The pressure increase used for the deposition of CO2 was very low, 10-9 mbar, to enable the formation of highly amorphous CO2 ice, at very low deposition rate. The transmittance infrared spectra, collected at several stages of sample growth, from 20 to 360 monolayers, are shown in the Figure. In a different set of experiments performed at IEM, the morphology of the amorphous CO2 ice has been studied using reflexion-absorption infrared (RAIR) spectroscopy. Calculated spectra of amorphous CO2 ice are obtained using the SIESTA code (2). In a first step, crystalline structures are processed by molecular dynamics to generate amorphous samples, which are subsequently relaxed until an equilibrium configuration is reached. The vibrational spectra of the amorphous solids are then calculated. The spectra of amorphous ice can change significantly depending on the density of the sample. An IR band, red-shifted with respect to ν3, has been identified as a witness of pure and amorphous CO2 ice. It vanishes when the sample becomes crystalline, either by temperature increase or by accumulation of increasing number of layers. The absence of this band in the observed spectra of solid CO2 is an indication that there is no pure and amorphous CO2 ice in inter- and circumstellar mantles References 1. Escribano, R., Muñoz Caro, G., Cruz-Díaz, G.A. Rodríguez-Lazcano, Y. and Maté, B., PNAS, accepted for publication, July 2013.. 2

  15. Investigation of the iced flowfield characteristics related to the stall margin instrumentation used in icing conditions

    NASA Astrophysics Data System (ADS)

    Pederson, Erik Thomas

    The purpose of this dissertation is to investigate the relationship between the flowfield surrounding an iced airfoil and the stall margin instrumentation developed for use in icing conditions. The stall margin system indicates to the pilot the change in available lift due to ice accretions on the leading edge of an airfoil. This system displays the change in the form of a normalized lift coefficient. Four pressure ports are chosen to specifically maintain a constant calibration curve, for pressure versus normalized lift coefficient, regardless of ice shape. This allows these pressures to be used to determine the change in maximum lift coefficient. The instrumentation currently maintains an accuracy of +/-10%. There was a need to investigate the relationship between the flowfield and the port locations, and the airfoil shape and the port locations. This allowed further understanding of the placement of these ports. Through this investigation, better port locations have been determined and the accuracy and usefulness of the instrumentation has been increased. This investigation was conducted using wind tunnel testing techniques. A 2-D NACA 23012 pressure model and a 2-D NACA 23012 force model were constructed and tested to determine initial port locations for the stall margin instrumentation. Simulated ice shapes were produced using the LEWICE software from NASA Glenn. The flowfield around the airfoil was mapped using smoke wire flow visualization and hotwire anemometry. A single wire system was used to determine a 2-D profile of the turbulence intensity levels surrounding the ice covered wing. The movement of the separation region behind the ice shape, with change in angle of attack, was also investigated. The relationship between this movement and the port locations was documented and its significance determined. Through these observations, better port locations for the stall margin instrumentation were determined thus allowing accuracy of the instrumentation to

  16. Changing Sea Ice Conditions in the Northwest Passage

    NASA Astrophysics Data System (ADS)

    Tivy, A. C.; Howell, S.; Agnew, T.; Derksen, C.

    2010-12-01

    The Northwest Passage lies in the middle of Canadian Arctic Archipelago providing a potential deepwater route that links the Atlantic and Pacific Oceans. Discovered by Sir Robert M’Clure in the 1850s, ever-present multi-year ice (MYI) has always prevented its practical navigation. 2007 marked extreme low MYI conditions in the Arctic and temporarily cleared the Northwest Passage. However, is one single clearing event within the Northwest Passage over the past 40 years indicative of future clearings? This analysis addressed two inter-related questions: i) why has the Northwest Passage contained historically heavy amounts of MYI? and ii) will decreases in MYI within the Northwest Passage continue into the future? Results indicate that for nearly 4 decades, the southern regions of the Canadian Arctic Archipelago have continuously operated as a drain-trap for MYI and this mechanism is responsible for maintaining the heavy MYI conditions within the Northwest Passage. The oldest and thickest MYI in the world resides along the northern flank of the Canadian Arctic Archipelago therefore, as the transition to a sea ice-free Arctic continues, MYI from this region will continue to migrate southward to the channels of the Northwest Passage. Results also find that 2007 was indeed an anomalously light sea ice year in the Northwest Passage but record low ice conditions have since been observed as of mid-August 2010.

  17. Preliminary Survey of Icing Conditions Measured During Routine Transcontinental Airline Operation

    NASA Technical Reports Server (NTRS)

    Perkins, Porter J.

    1952-01-01

    Icing data collected on routine operations by four DC-4-type aircraft equipped with NACA pressure-type icing-rate meters are presented as preliminary information obtained from a statistical icing data program sponsored by the NACA with the cooperation of many airline companies and the United States Air Force. The program is continuing on a much greater scale to provide large quantities of data from many air routes in the United States and overseas. Areas not covered by established air routes are also being included in the survey. The four aircraft which collected the data presented in this report were operated by United Air Lines over a transcontinental route from January through May, 1951. An analysis of the pressure-type icing-rate meter was satisfactory for collecting statistical data during routine operations. Data obtained on routine flight icing encounters from.these four instrumented aircraft, although insufficient for a conclusive statistical analysis, provide a greater quantity and considerably more realistic information than that obtained from random research flights. A summary of statistical data will be published when the information obtained daring the 1951-52 icing season and that to be obtained during the 1952-53 season can be analyzed and assembled. The 1951-52 data already analyzed indicate that the quantity, quality, and range of icing information being provided by this expanded program should afford a sound basis for ice-protection-system design by defining the important meteorological parameters of the icing cloud.

  18. Aerodynamic heating and the deflection of drops by an obstacle in an air stream in relation to aircraft icing

    NASA Technical Reports Server (NTRS)

    Kantrowitz, Arthur

    1940-01-01

    Two topics of interest to persons attempting to apply the heat method of preventing ice formation on aircraft are considered. Surfaces moving through air at high speed are shown, both theoretically and experimentally, to be subject to important aerodynamic heating effects that will materially reduce the heat required to prevent ice. Numerical calculations of the path of water drops in an air stream around a circular cylinder are given. From these calculations, information is obtained on the percentage of the swept area cleared of drops.

  19. 78 FR 50317 - Special Conditions: Cessna Aircraft Company, Model J182T; Diesel Cycle Engine Installation

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-19

    ...These special conditions are issued for the Cessna Aircraft Company (Cessna) Model J182T airplane. This airplane will have a novel or unusual design feature(s) associated with the installation of an aircraft diesel engine (ADE). The applicable airworthiness regulations do not contain adequate or appropriate safety standards for this design feature. These special conditions contain the......

  20. 32 CFR 766.5 - Conditions governing use of aviation facilities by civil aircraft.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 32 National Defense 5 2012-07-01 2012-07-01 false Conditions governing use of aviation facilities... OF THE NAVY MISCELLANEOUS RULES USE OF DEPARTMENT OF THE NAVY AVIATION FACILITIES BY CIVIL AIRCRAFT § 766.5 Conditions governing use of aviation facilities by civil aircraft. (a) Risk. The use of Navy...

  1. 32 CFR 766.5 - Conditions governing use of aviation facilities by civil aircraft.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 32 National Defense 5 2013-07-01 2013-07-01 false Conditions governing use of aviation facilities... OF THE NAVY MISCELLANEOUS RULES USE OF DEPARTMENT OF THE NAVY AVIATION FACILITIES BY CIVIL AIRCRAFT § 766.5 Conditions governing use of aviation facilities by civil aircraft. (a) Risk. The use of Navy...

  2. 32 CFR 766.5 - Conditions governing use of aviation facilities by civil aircraft.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 32 National Defense 5 2014-07-01 2014-07-01 false Conditions governing use of aviation facilities... OF THE NAVY MISCELLANEOUS RULES USE OF DEPARTMENT OF THE NAVY AVIATION FACILITIES BY CIVIL AIRCRAFT § 766.5 Conditions governing use of aviation facilities by civil aircraft. (a) Risk. The use of Navy...

  3. 32 CFR 766.5 - Conditions governing use of aviation facilities by civil aircraft.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 5 2010-07-01 2010-07-01 false Conditions governing use of aviation facilities... OF THE NAVY MISCELLANEOUS RULES USE OF DEPARTMENT OF THE NAVY AVIATION FACILITIES BY CIVIL AIRCRAFT § 766.5 Conditions governing use of aviation facilities by civil aircraft. (a) Risk. The use of Navy...

  4. 32 CFR 766.5 - Conditions governing use of aviation facilities by civil aircraft.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 32 National Defense 5 2011-07-01 2011-07-01 false Conditions governing use of aviation facilities... OF THE NAVY MISCELLANEOUS RULES USE OF DEPARTMENT OF THE NAVY AVIATION FACILITIES BY CIVIL AIRCRAFT § 766.5 Conditions governing use of aviation facilities by civil aircraft. (a) Risk. The use of Navy...

  5. Aircraft

    DOEpatents

    Hibbs, B.D.; Lissaman, P.B.S.; Morgan, W.R.; Radkey, R.L.

    1998-09-22

    This disclosure provides a solar rechargeable aircraft that is inexpensive to produce, is steerable, and can remain airborne almost indefinitely. The preferred aircraft is a span-loaded flying wing, having no fuselage or rudder. Travelling at relatively slow speeds, and having a two-hundred foot wingspan that mounts photovoltaic cells on most all of the wing`s top surface, the aircraft uses only differential thrust of its eight propellers to turn. Each of five sections of the wing has one or more engines and photovoltaic arrays, and produces its own lift independent of the other sections, to avoid loading them. Five two-sided photovoltaic arrays, in all, are mounted on the wing, and receive photovoltaic energy both incident on top of the wing, and which is incident also from below, through a bottom, transparent surface. The aircraft is capable of a top speed of about ninety miles per hour, which enables the aircraft to attain and can continuously maintain altitudes of up to sixty-five thousand feet. Regenerative fuel cells in the wing store excess electricity for use at night, such that the aircraft can sustain its elevation indefinitely. A main spar of the wing doubles as a pressure vessel that houses hydrogen and oxygen gases for use in the regenerative fuel cell. The aircraft has a wide variety of applications, which include weather monitoring and atmospheric testing, communications, surveillance, and other applications as well. 31 figs.

  6. Aircraft

    DOEpatents

    Hibbs, Bart D.; Lissaman, Peter B. S.; Morgan, Walter R.; Radkey, Robert L.

    1998-01-01

    This disclosure provides a solar rechargeable aircraft that is inexpensive to produce, is steerable, and can remain airborne almost indefinitely. The preferred aircraft is a span-loaded flying wing, having no fuselage or rudder. Travelling at relatively slow speeds, and having a two-hundred foot wingspan that mounts photovoltaic cells on most all of the wing's top surface, the aircraft uses only differential thrust of its eight propellers to turn. Each of five sections of the wing has one or more engines and photovoltaic arrays, and produces its own lift independent of the other sections, to avoid loading them. Five two-sided photovoltaic arrays, in all, are mounted on the wing, and receive photovoltaic energy both incident on top of the wing, and which is incident also from below, through a bottom, transparent surface. The aircraft is capable of a top speed of about ninety miles per hour, which enables the aircraft to attain and can continuously maintain altitudes of up to sixty-five thousand feet. Regenerative fuel cells in the wing store excess electricity for use at night, such that the aircraft can sustain its elevation indefinitely. A main spar of the wing doubles as a pressure vessel that houses hydrogen and oxygen gasses for use in the regenerative fuel cell. The aircraft has a wide variety of applications, which include weather monitoring and atmospheric testing, communications, surveillance, and other applications as well.

  7. Icing flight research: Aerodynamic effects of ice and ice shape documentation with stereo photography

    NASA Technical Reports Server (NTRS)

    Mikkelsen, K. L.; Mcknight, R. C.; Ranaudo, R. J.; Perkins, P. J., Jr.

    1985-01-01

    Aircraft icing flight research was performed in natural icing conditions. A data base consisting of icing cloud measurements, ice shapes, and aerodynamic measurements is being developed. During research icing encounters the icing cloud was continuously measured. After the encounter, the ice accretion shapes on the wing were documented with a stereo camera system. The increase in wing section drag was measured with a wake survey probe. The overall aircraft performance loss in terms of lift and drag coefficient changes was obtained by steady level speed/power measurements. Selective deicing of the airframe components was performed to determine their contributions to the total drag increase. Engine out capability in terms of power available was analyzed for the iced aircraft. It was shown that the stereo photography system can be used to document ice shapes in flight and that the wake survey probe can measure increases in wing section drag caused by ice. On one flight, the wing section drag coefficient (c sub d) increased approximately 120 percent over the uniced baseline at an aircraft angle of attack of 6 deg. On another flight, the aircraft darg coefficient (c sub d) increased by 75 percent over the uniced baseline at an aircraft lift coefficient (C sub d) of 0.5.

  8. Shedding of Water Drops from a Surface under Icing Conditions.

    PubMed

    Mandal, Deepak Kumar; Criscione, Antonio; Tropea, C; Amirfazli, A

    2015-09-01

    A sessile water drop exposed to an air flow will shed if the adhesion is overcome by the external aerodynamic forces on the drop. In this study, shedding of water drops were investigated under icing conditions, on surfaces with different wettabilities, from hydrophilic to superhydrophobic. A wind tunnel was used for experiments in a temperature range between -8 and 24.5 °C. Results indicate that the temperature has a major influence on the incipient motion of drop shedding. The critical air velocity (U(c)) at which a drop first starts to shed generally increases under icing conditions, indicating an increase in the adhesion force. The contact angle hysteresis (CAH) and the drop base length (L(b)) are found to be the controlling factors for adhesion. A correlation was also developed to deduce the drag coefficient, C(D) for the drop. It was found that C(D) can decrease under icing conditions. In general, a lower C(D) and higher adhesion together lead to a higher critical air velocity. However, there are systems such as water on Teflon for which the critical air velocity remains practically unaffected by temperature because of similar adhesion and C(D) values, at all temperatures tested. PMID:26261936

  9. Biofuel Blending Impacts on Aircraft Engine Particle Emissions at Cruise Conditions

    NASA Astrophysics Data System (ADS)

    Moore, R.

    2015-12-01

    We present measurements of aerosol emissions indices and microphysical properties measured in-situ behind the CFM56-2-C1 engines of the NASA DC-8 aircraft during the 2014 Alternative Fuel Effects on Contrails and Cruise Emissions (ACCESS) project. Aircraft engine emissions can have a disproportionately large climatic impact since they are emitted high in the troposphere and in remote regions with otherwise low aerosol concentrations. This has motivated numerous past ground-based studies focused on quantifying the emissions indices of non-volatile and semi-volatile aerosol species, however, it is unclear the extent to which emissions on the ground translate to emissions at cruise conditions. In addition, the ability of engine-emitted aerosols to nucleate ice crystals and form linear contrails or contrail cirrus clouds remains poorly understood. To better understand these effects, two chase plane experiments were carried out in 2013 and 2014. Three different fuel types are discussed: a low-sulfur JP-8 fuel, a 50:50 blend of JP-8 and a camelina-based HEFA fuel, and the JP-8 fuel doped with sulfur. Emissions were sampled using a large number of aerosol and gas instruments integrated on HU-25 and Falcon 20 jets that were positioned in the DC-8 exhaust plume at approximately 50-500 m distance behind the engines. It was found that the biojet fuel blend substantially decreases the aerosol number and mass emissions indices, while the gas phase emission indices were similar across fuels. The magnitude of the effects of these fuel-induced changes of aerosol emissions and implications for future aviation biofuel blending impacts will be discussed.

  10. 78 FR 37958 - Special Conditions: Cessna Aircraft Company, Model J182T; Electronic Engine Control System...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-25

    ... Federal Aviation Administration 14 CFR Part 23 Special Conditions: Cessna Aircraft Company, Model J182T... Cessna Aircraft Company (Cessna) Model J182T airplane. This airplane will have a novel or unusual design..., 2000 (65 FR 19477-19478), as well as at http://DocketsInfo.dot.gov . Docket: Background documents...

  11. Onset of atmospheric ice formation in natural conditions

    NASA Astrophysics Data System (ADS)

    Conen, Franz; Zimmermann, Lukas

    2015-04-01

    Bacteria growing on plants are the particles with the warmest freezing temperature known for natural particles (-2 oC). Their onset of freezing is known to be conditioned by themperature, growth and nutrient status, and probably other factors that can not be assessed in situ, but are also not likely to be conserved when taking airborne bacteria to the laboratory. Whether such bacteria play a role in initiating the ice phase in clouds is therefore best studied directly in a cooling air mass in the natural environment. Investigations directly at cloud tops would be desirable. A more amenable place is the bottom of a valley where a cold air pool forms during clear nights and when radiation fog is likely to form. When shallow, such fog may resemble an inverted cloud with its top on the land surface and warmer air above it. The temperature of bacteria and other particles suspended in air under a clear sky around the onset of fog formation is probably several degrees below that of the surrounding air because of radiative cooling, which will affect the particle's activation as a cloud condensation nucleus and as an ice nucleus. Hence, ice particles probably form earlier than expected at a particular air temperature, grow rapidly and parachute to the surface, where their descent can be recorded by traps charged with supercooled water. We present, and would like to discuss, this kind of observation in principle and show some first results (subject to suitable weather conditions before the presentation).

  12. Icing Conditions Over Northern Eurasia in Changing Climate

    NASA Astrophysics Data System (ADS)

    Bulygina, O.; Arzhanova, N.; Groisman, P. Y.

    2013-12-01

    Climate of the Russian Federation for the national territory. This Reference Book addresses the current state of these weather phenomena. However, the ongoing and projected humidity changes in the high latitudes will strongly affect the circum-polar area (land and ocean) and impact the frequency and intensity of these potentially dangerous weather phenomena across the entire extratropical land area. Therefore the goal of the present study is to quantify icing conditions over the northern Eurasia. Our analysis includes data of 958 Russian stations from 1977 to 2012. Regional analysis of gololed characteristics was carried out using quasi-homogeneous climatic regions. Maps (climatology, trends) are presented mostly for visualization purposes. The area-averaging technique using station values converted to anomalies with respect to a common reference period (in this study, from 1977 to 2012). Anomalies were arithmetically averaged first within 1N x 2E grid cells and thereafter by a weighted average value derived over the quasi-homogeneous climatic regions. This approach provides a more uniform spatial field for averaging.

  13. Development, Implementation, and Pilot Evaluation of a Model-Driven Envelope Protection System to Mitigate the Hazard of In-Flight Ice Contamination on a Twin-Engine Commuter Aircraft

    NASA Technical Reports Server (NTRS)

    Martos, Borja; Ranaudo, Richard; Norton, Billy; Gingras, David; Barnhart, Billy

    2014-01-01

    Fatal loss-of-control accidents have been directly related to in-flight airframe icing. The prototype system presented in this report directly addresses the need for real-time onboard envelope protection in icing conditions. The combination of prior information and real-time aerodynamic parameter estimations are shown to provide sufficient information for determining safe limits of the flight envelope during inflight icing encounters. The Icing Contamination Envelope Protection (ICEPro) system was designed and implemented to identify degradations in airplane performance and flying qualities resulting from ice contamination and provide safe flight-envelope cues to the pilot. The utility of the ICEPro system for mitigating a potentially hazardous icing condition was evaluated by 29 pilots using the NASA Ice Contamination Effects Flight Training Device. Results showed that real time assessment cues were effective in reducing the number of potentially hazardous upset events and in lessening exposure to loss of control following an incipient upset condition. Pilot workload with the added ICEPro displays was not measurably affected, but pilot opinion surveys showed that real time cueing greatly improved their awareness of a hazardous aircraft state. The performance of ICEPro system was further evaluated by various levels of sensor noise and atmospheric turbulence.

  14. Role of ice dynamics in anomalous ice conditions in the Beaufort Sea during 2006 and 2007

    NASA Astrophysics Data System (ADS)

    Hutchings, J. K.; Rigor, I. G.

    2012-05-01

    A new record minimum in summer sea ice extent was set in 2007 and an unusual polynya formed in the Beaufort Sea ice cover during the summer of 2006. Using a combination of visual observations from cruises, ice drift, and satellite passive microwave sea ice concentration, we show that ice dynamics during preceding years included events that preconditioned the Beaufort ice pack for the unusual patterns of opening observed in both summers. Intrusions of first year ice from the Chukchi Sea to the Northern Beaufort, and increased pole-ward ice transport from the western Arctic during summer has led to reduced replenishment of multiyear ice, older than five years, in the western Beaufort, resulting in a younger, thinner ice pack in most of the Beaufort. We find ice younger than five years melts out completely by the end of summer, south of 76N. The 2006 unusual polynya was bounded to the south by an ice tongue composed of sea ice older than 5 years, and formed when first year and second year ice melted between 76N and the older ice to the south. In this paper we demonstrate that a recent shift in ice circulation patterns in the western Arctic preconditions the Beaufort ice pack for increased seasonal ice zone extent.

  15. Capture Conditions for Merging Trajectory Segments to Model Realistic Aircraft Descents

    NASA Technical Reports Server (NTRS)

    Zhao, Yiyuan; Slattery, Rhonda A.

    1996-01-01

    A typical commercial aircraft trajectory consists of a series of flight segments. An aircraft switches from one segment to another when certain specified variables reach their desired values. Trajectory synthesis for air traffic control automation must be consistent with practical pilot procedures. We examine capture conditions for merging trajectory segments to model commercial aircraft descent in trajectory synthesis. These conditions translate into bounds on measurements of atmospheric wind, pressure, and temperature. They also define ranges of thrust and drag feasible for a descent trajectory. Capture conditions are derived for the Center-TRACON Automation System developed at NASA Ames Research Center for automated air traffic control. Various uses of capture conditions are discussed. A Boeing 727-200 aircraft is used to provide numerical examples of capture conditions.

  16. Overview of Icing Research at NASA Glenn

    NASA Technical Reports Server (NTRS)

    Kreeger, Richard E.

    2013-01-01

    The aviation industry continues to deal with icing-related incidents and accidents on a regular basis. Air traffic continues to increase, placing more aircraft in adverse icing conditions more frequently and for longer periods. Icing conditions once considered rare or of little consequence, such as super-cooled large droplet icing or high altitude ice crystals, have emerged as major concerns for modern aviation. Because of this, there is a need to better understand the atmospheric environment, the fundamental mechanisms and characteristics of ice growth, and the aerodynamic effects due to icing, as well as how best to protect these aircraft. The icing branch at NASA Glenn continues to develop icing simulation methods and engineering tools to address current aviation safety issues in airframe, engine and rotorcraft icing.

  17. Propaganda, News, or Education: Reporting Changing Arctic Sea Ice Conditions

    NASA Astrophysics Data System (ADS)

    Leitzell, K.; Meier, W.

    2010-12-01

    The National Snow and Ice Data Center provides information on Arctic sea ice conditions via the Arctic Sea Ice News & Analysis (ASINA) website. As a result of this effort to explain climatic data to the general public, we have attracted a huge amount of attention from our readers. Sometimes, people write to thank us for the information and the explanation. But people also write to accuse us of bias, slant, or outright lies in our posts. The topic of climate change is a minefield full of political animosity, and even the most carefully written verbiage can appear incomplete or biased to some audiences. Our strategy has been to report the data and stick to the areas in which our scientists are experts. The ASINA team carefully edits our posts to make sure that all statements are based on the science and not on opinion. Often this means using some technical language that may be difficult for a layperson to understand. However, we provide concise definitions for technical terms where appropriate. The hope is that by communicating the data clearly, without an agenda, we can let the science speak for itself. Is this an effective strategy to communicate clearly about the changing climate? Or does it downplay the seriousness of climate change? By writing at a more advanced level and avoiding oversimplification, we require our readers to work harder. But we may also maintain the attention of skeptics, convincing them to read further and become more knowledgeable about the topic.

  18. [Tail Plane Icing

    NASA Technical Reports Server (NTRS)

    1997-01-01

    The Aviation Safety Program initiated by NASA in 1997 has put greater emphasis in safety related research activities. Ice-contaminated-tailplane stall (ICTS) has been identified by the NASA Lewis Icing Technology Branch as an important activity for aircraft safety related research. The ICTS phenomenon is characterized as a sudden, often uncontrollable aircraft nose- down pitching moment, which occurs due to increased angle-of-attack of the horizontal tailplane resulting in tailplane stall. Typically, this phenomenon occurs when lowering the flaps during final approach while operating in or recently departing from icing conditions. Ice formation on the tailplane leading edge can reduce tailplane angle-of-attack range and cause flow separation resulting in a significant reduction or complete loss of aircraft pitch control. In 1993, the Federal Aviation Authority (FAA) and NASA embarked upon a four-year research program to address the problem of tailplane stall and to quantify the effect of tailplane ice accretion on aircraft performance and handling characteristics. The goals of this program, which was completed in March 1998, were to collect aerodynamic data for an aircraft tail with and without ice contamination and to develop analytical methods for predicting the effects of tailplane ice contamination. Extensive dry air and icing tunnel tests which resulted in a database of the aerodynamic effects associated with tailplane ice contamination. Although the FAA/NASA tailplane icing program generated some answers regarding ice-contaminated-tailplane stall (ICTS) phenomena, NASA researchers have found many open questions that warrant further investigation into ICTS. In addition, several aircraft manufacturers have expressed interest in a second research program to expand the database to other tail configurations and to develop experimental and computational methodologies for evaluating the ICTS phenomenon. In 1998, the icing branch at NASA Lewis initiated a second

  19. Application of new GPS aircraft control/display system to topographic mapping of the Greenland ice cap

    SciTech Connect

    Wright, C.W.; Swift, R.N.

    1996-10-01

    NASA has completed an accurate baseline map of the elevation of the Greenland ice sheet using a scanning airborne lidar in combination with differential kinematic Global Positioning System (GPS) techniques. The present plan is to reoccupy these survey lines which are spread over the major regions of the ice sheet beginning in 1997. The results are expected to provide a quantitative answer on how the ice sheet is responding to regional climatic changes. Navigation to within +-100 m of the desired track over lengths of up to 1,000 km are a requirement for the success of the program. To meet this navigational requirement, NASA developed the GPS Flight Management System (GFMS). GFMS is a PC based system that uses the real-time position update from a single GPS receiver located on the aircraft to calculate a cross-track error and generates aircraft steering commands which are converted into analog Instrument Landing System (OM) signals using an RF generator. TU GFMS also updates a cockpit display. 4 refs., 6 figs.

  20. NASA-Langley Research Center's Aircraft Condition Analysis and Management System Implementation

    NASA Technical Reports Server (NTRS)

    Frye, Mark W.; Bailey, Roger M.; Jessup, Artie D.

    2004-01-01

    This document describes the hardware implementation design and architecture of Aeronautical Radio Incorporated (ARINC)'s Aircraft Condition Analysis and Management System (ACAMS), which was developed at NASA-Langley Research Center (LaRC) for use in its Airborne Research Integrated Experiments System (ARIES) Laboratory. This activity is part of NASA's Aviation Safety Program (AvSP), the Single Aircraft Accident Prevention (SAAP) project to develop safety-enabling technologies for aircraft and airborne systems. The fundamental intent of these technologies is to allow timely intervention or remediation to improve unsafe conditions before they become life threatening.

  1. Monitoring Sea Ice Conditions and Use in Arctic Alaska to Enhance Community Adaptation to Change

    NASA Astrophysics Data System (ADS)

    Druckenmiller, M. L.; Eicken, H.

    2010-12-01

    Sea ice changes in the coastal zone, while less conspicuous in relation to the dramatic thinning and retreat of perennial Arctic sea ice, can be more readily linked to local impacts. Shorefast ice is a unique area for interdisciplinary research aimed at improving community adaptation to climate through local-scale environmental observations. Here, geophysical monitoring, local Iñupiat knowledge, and the documented use of ice by the Native hunting community of Barrow, Alaska are combined to relate coastal ice processes and morphologies in the Chukchi Sea to ice stability and community adaption strategies for travel, hunting, and risk assessment. A multi-year effort to map and survey the community’s seasonal ice trails, alongside a detailed record of shorefast ice conditions, provides insight into how hunters evaluate the evolution of ice throughout winter and spring. Various data sets are integrated to relate the annual accretion history of the local ice cover to both measurements of ice thickness and topography and hunter observations of ice types and hazards. By relating changes in the timing of shorefast ice stabilization, offshore ice conditions, and winter wind patterns to ice characteristics in locations where spring bowhead whaling occurs, we are working toward an integrated scientific product compatible with the perspective of local ice experts. A baseline for assessing future change and community climate-related vulnerabilities may not be characterized by single variables, such as ice thickness, but rather by how changes in observable variables manifest in impacts to human activities. This research matches geophysical data to ice-use to establish such a baseline. Documenting human-environment interactions will allow future monitoring to illustrate how strategies for continued community ice-use are indicative of or responsive to change, and potentially capable of incorporating science products as additional sources of useable information.

  2. Modelling ice conditions in the easternmost Gulf of Finland in the Baltic Sea

    NASA Astrophysics Data System (ADS)

    Ryabchenko, Vladimir; Dvornikov, Anton; Haapala, Jari; Myrberg, Kai

    2010-07-01

    To model ice conditions in the eastern Gulf of Finland, a high-resolution three-dimensional hydrodynamic model is coupled with the advanced sea-ice model HELMI ( Haapala et al., 2005). To test the model in extreme situations, the ice pattern in the eastern Gulf of Finland was simulated for a mild ice winter (2007-2008) and for a moderate one (2003-2004). The reference runs were performed on the assumption that the ice in the model domain is fast ice if the sea depth is less than 10 m. Using this assumption, the ice thickness averaged over the Neva Bay (the easternmost part of the Gulf of Finland) is overestimated by the model for almost the entire wintertime in the mild winter and during the ice formation and melting periods in the moderate winter, as compared with the thickness reported in ice charts. For both winters, the model solution without the assumption of a fast ice region is in better agreement with averaged ice thicknesses from ice charts during the ice formation and ice melting periods. The addition of snow on the ice surface in the model without a fast ice region led to a significant decrease of ice thickness during the entire wintertime period for the moderate winter, so that the model agrees well with the ice thickness estimated from observations. At the same time, the decrease of ice thickness in the mild winter was not strong enough, and the model overestimated the observed ice thickness in the Neva Bay in January-March by about 10 cm. We will show that possible reasons for this are heat sources (warm wastewater) within the Neva Bay and uncertainties in the assumed river temperature. In the case of no fast ice region and snow on ice, the model correctly simulates the spatial distribution of ice thickness seen on ice charts for the mild winter. Despite the absence of irregularities in wind forcing - which was assumed to be homogeneous over the model domain - the modelled ice thickness distributions included meso-scale features such as the ridged and

  3. Airframe Icing Research Gaps: NASA Perspective

    NASA Technical Reports Server (NTRS)

    Potapczuk, Mark

    2009-01-01

    qCurrent Airframe Icing Technology Gaps: Development of a full 3D ice accretion simulation model. Development of an improved simulation model for SLD conditions. CFD modeling of stall behavior for ice-contaminated wings/tails. Computational methods for simulation of stability and control parameters. Analysis of thermal ice protection system performance. Quantification of 3D ice shape geometric characteristics Development of accurate ground-based simulation of SLD conditions. Development of scaling methods for SLD conditions. Development of advanced diagnostic techniques for assessment of tunnel cloud conditions. Identification of critical ice shapes for aerodynamic performance degradation. Aerodynamic scaling issues associated with testing scale model ice shape geometries. Development of altitude scaling methods for thermal ice protections systems. Development of accurate parameter identification methods. Measurement of stability and control parameters for an ice-contaminated swept wing aircraft. Creation of control law modifications to prevent loss of control during icing encounters. 3D ice shape geometries. Collection efficiency data for ice shape geometries. SLD ice shape data, in-flight and ground-based, for simulation verification. Aerodynamic performance data for 3D geometries and various icing conditions. Stability and control parameter data for iced aircraft configurations. Thermal ice protection system data for simulation validation.

  4. Ice Accretion Measurements on an Airfoil and Wedge in Mixed-Phase Conditions

    NASA Technical Reports Server (NTRS)

    Struk, Peter; Bartkus, Tadas; Tsao, Jen-Ching; Currie, Tom; Fuleki, Dan

    2015-01-01

    This paper describes ice accretion measurements from experiments conducted at the National Research Council (NRC) of Canada's Research Altitude Test Facility during 2012. Due to numerous engine power loss events associated with high altitude convective weather, potential ice accretion within an engine due to ice crystal ingestion is being investigated collaboratively by NASA and NRC. These investigations examine the physical mechanisms of ice accretion on surfaces exposed to ice crystal and mixed phase conditions, similar to those believed to exist in core compressor regions of jet engines. A further objective of these tests is to examine scaling effects since altitude appears to play a key role in this icing process.

  5. Experimental investigation of static ice refrigeration air conditioning system driven by distributed photovoltaic energy system

    NASA Astrophysics Data System (ADS)

    Xu, Y. F.; Li, M.; Luo, X.; Wang, Y. F.; Yu, Q. F.; Hassanien, R. H. E.

    2016-08-01

    The static ice refrigeration air conditioning system (SIRACS) driven by distributed photovoltaic energy system (DPES) was proposed and the test experiment have been investigated in this paper. Results revealed that system energy utilization efficiency is low because energy losses were high in ice making process of ice slide maker. So the immersed evaporator and co-integrated exchanger were suggested in system structure optimization analysis and the system COP was improved nearly 40%. At the same time, we have researched that ice thickness and ice super-cooled temperature changed along with time and the relationship between system COP and ice thickness was obtained.

  6. Meteorological conditions influencing the formation of level ice within the Baltic Sea

    NASA Astrophysics Data System (ADS)

    Mazur, A. K.; Krezel, A.

    2012-12-01

    The Baltic Sea is covered by ice every winter and on average, the ice-covered area is 45% of the total area of the Baltic Sea. The beginning of ice season usually starts in the end of November, ice extent is the largest between mid-February and mid-March and sea ice disappears completely in May. The ice covered areas during a typical winter are the Gulf of Bothnia, the Gulf of Finland and the Gulf of Riga. The studies of sea ice in the Baltic Sea are related to two aspects: climate and marine transport. Depending on the local weather conditions during the winter different types of sea ice can be formed. From the point of winter shipping it is important to locate level and deformed ice areas (rafted ice, ridged ice, and hummocked ice). Because of cloud and daylight independency as well as good spatial resolution, SAR data seems to be the most suitable source of data for sea ice observation in the comparatively small area of the Baltic Sea. We used ASAR Wide Swath Mode data with spatial resolution 150 m. We analyzed data from the three winter seasons which were examples of severe, typical and mild winters. To remove the speckle effect the data were resampled to 250 m pixel size and filtred using Frost filter 5x5. To detect edges we used Sobel filter. The data were also converted into grayscale. Sea ice classification was based on Object-Based Image Analysis (OBIA). Object-based methods are not a common tool in sea ice studies but they seem to accurately separate level ice within the ice pack. The data were segmented and classified using eCognition Developer software. Level ice were classified based on texture features defined by Haralick (Grey Level Co-Occurrence Matrix homogeneity, GLCM contrast, GLCM entropy and GLCM correlation). The long-term changes of the Baltic Sea ice conditions have been already studied. They include date of freezing, date of break-up, sea ice extent and some of work also ice thickness. There is a little knowledge about the relationship of

  7. Reactivity of xenon with ice at planetary conditions.

    PubMed

    Sanloup, Chrystèle; Bonev, Stanimir A; Hochlaf, Majdi; Maynard-Casely, Helen E

    2013-06-28

    We report results from high pressure and temperature experiments that provide evidence for the reactivity of xenon with water ice at pressures above 50 GPa and a temperature of 1500 K-conditions that are found in the interiors of Uranus and Neptune. The x-ray data are sufficient to determine a hexagonal lattice with four Xe atoms per unit cell and several possible distributions of O atoms. The measurements are supplemented with ab initio calculations, on the basis of which a crystallographic structure with a Xe4O12H12 primitive cell is proposed. The newly discovered compound is formed in the stability fields of superionic ice and η-O2, and has the same oxygen subnetwork as the latter. Furthermore, it has a weakly metallic character and likely undergoes sublattice melting of the H subsystem. Our findings indicate that Xe is expected to be depleted in the atmospheres of the giant planets as a result of sequestration at depth. PMID:23848893

  8. Reactivity of xenon with ice at planetary conditions.

    PubMed

    Sanloup, Chrystèle; Bonev, Stanimir A; Hochlaf, Majdi; Maynard-Casely, Helen E

    2013-06-28

    We report results from high pressure and temperature experiments that provide evidence for the reactivity of xenon with water ice at pressures above 50 GPa and a temperature of 1500 K-conditions that are found in the interiors of Uranus and Neptune. The x-ray data are sufficient to determine a hexagonal lattice with four Xe atoms per unit cell and several possible distributions of O atoms. The measurements are supplemented with ab initio calculations, on the basis of which a crystallographic structure with a Xe4O12H12 primitive cell is proposed. The newly discovered compound is formed in the stability fields of superionic ice and η-O2, and has the same oxygen subnetwork as the latter. Furthermore, it has a weakly metallic character and likely undergoes sublattice melting of the H subsystem. Our findings indicate that Xe is expected to be depleted in the atmospheres of the giant planets as a result of sequestration at depth.

  9. A Database of Supercooled Large Droplet Ice Accretions

    NASA Technical Reports Server (NTRS)

    VanZante, Judith Foss

    2007-01-01

    A unique, publicly available database regarding supercooled large droplet ice accretions has been developed in NASA Glenn's Icing Research Tunnel. Identical cloud and flight conditions were generated for five different airfoil models. The models chosen represent a variety of aircraft types from the horizontal stabilizer of a large trans-port aircraft to the wings of regional, business, and general aviation aircraft. In addition to the standard documentation methods of 2D ice shape tracing and imagery, ice mass measurements were also taken. This database will also be used to validate and verify the extension of the ice accretion code, LEWICE, into the SLD realm.

  10. A Database of Supercooled Large Droplet Ice Accretions [Supplement

    NASA Technical Reports Server (NTRS)

    VanZante, Judith Foss

    2007-01-01

    A unique, publicly available database regarding supercooled large droplet (SLD) ice accretions has been developed in NASA Glenn's Icing Research Tunnel. Identical cloud and flight conditions were generated for five different airfoil models. The models chosen represent a variety of aircraft types from the horizontal stabilizer of a large transport aircraft to the wings of regional, business, and general aviation aircraft. In addition to the standard documentation methods of 2D ice shape tracing and imagery, ice mass measurements were also taken. This database will also be used to validate and verify the extension of the ice accretion code, LEWICE, into the SLD realm.

  11. Holocene Fluctuations of North Ice Cap, a Proxy for Climate Conditions along the Northwestern Margin of the Greenland Ice Sheet

    NASA Astrophysics Data System (ADS)

    Kelly, M. A.; Osterberg, E. C.; Lasher, G. E.; Farnsworth, L. B.; Howley, J. A.; Axford, Y.; Zimmerman, S. R. H.

    2015-12-01

    North Ice Cap (~76.9°N, 68°W, summit elevation 1322 m asl), a small, independent ice cap in northwestern Greenland, is located within ~25 km of the Greenland Ice Sheet margin and Harald Molkte Bræ outlet glacier. We present geochronological, geomorphic and sedimentological data constraining the Holocene extents of North Ice Cap and suggest that its past fluctuations can be used as a proxy for climate conditions along the northwestern margin of the Greenland Ice Sheet. Prior work by Goldthwait (1960) used glacial geomorphology and radiocarbon ages of subfossil plants emerging along shear planes in the ice cap margin to suggest that that North Ice Cap was not present during the early Holocene and nucleated in the middle to late Holocene time, with the onset of colder conditions. Subfossil plants emerging at shear planes in the North Ice Cap margin yield radiocarbon ages of ~4.8-5.9 cal kyr BP (Goldthwait, 1960) and ~AD 1000-1350 (950-600 cal yr BP), indicating times when the ice cap was smaller than at present. In situ subfossil plants exposed by recent ice cap retreat date to ~AD 1500-1840 (450-110 cal yr BP) and indicate small fluctuations of the ice cap margin. 10Be ages of an unweathered, lichen-free drift <100 m from the present North Ice Cap margin range from ~500 to 8000 yrs ago. We suggest that the drift was deposited during the last ~500 yrs and that the older 10Be ages are influenced by 10Be inherited from a prior period of exposure. We also infer ice cap fluctuations using geochemical data from a Holocene-long sediment core from Deltasø, a downstream lake that currently receives meltwater from North Ice Cap. The recent recession of the North Ice Cap margin influenced a catastrophic drainage of a large proglacial lake, Søndre Snesø, that our field team documented in August 2012. To our knowledge, this is the first significant lowering of Søndre Snesø in historical time.

  12. The development of a coupled ice-ocean model for forecasting ice conditions in the Arctic

    NASA Astrophysics Data System (ADS)

    Riedlinger, Shelley H.; Preller, Ruth H.

    1991-09-01

    A coupled ice-ocean model has been developed to investigate how a better simulation of ice-ocean interaction can improve sea ice forecasting capabilities. The coupling of the ice and ocean results in improved temporal variability of ocean circulation and heat and salt exchange between ice and ocean. The U.S. Navy's Polar Ice Prediction System is coupled to a diagnostic version of the Bryan-Cox three-dimensional ocean circulation model. A horizontal grid spacing of 127 km was used in the coupled model with 17 vertical levels from the surface to the ocean bottom. Atmospheric data from the Naval Operational Global Atmospheric Prediction System (NOGAPS) for 1986 were used to force the model. The ice-ocean model simulation yielded realistic ice thickness distributions, ice drifts, and ocean currents. The model predicted accurate seasonal trends in ice growth and decay. Excess ice is often grown in the Greenland and Barents seas in fall and winter. This is due, in part, to the model's grid resolution which does not accurately resolve narrow currents, such as the West Spitsbergen Current. A sensitivity study of the heat transfer coefficients used in the ice model showed that the ice edge could be improved by using different coefficient values for thick ice, thin ice, and open water. Other sensitivity studies examined the effect of removing the "distorted" physics frequently used in the Bryan-Cox ocean circulation model and the effect of the vertical eddy momentum coefficient on the surface ocean circulation. An additional simulation was made using 1989 NOGAPS forcing to examine what type of variability could occur when using different years of NOGAPS forcing in the diagnostic ocean model. Significant differences occurred between the 1989 and 1986 ice thickness distributions as well as the oceanic heat fluxes. These differences show that the forecast system, which presently uses an ocean "climatology," can benefit from the variability allowed by the diagnostic ocean model.

  13. 76 FR 19903 - Special Conditions: Diamond Aircraft Industry Model DA-40NG; Diesel Cycle Engine

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-11

    ...These special conditions are issued for the Diamond Aircraft Industry (DAI) GmbH model DA-40NG the Austro Engine GmbH model E4 aircraft diesel engine (ADE) using turbine (jet) fuel. This airplane will have a novel or unusual design feature(s) associated with the installation of a diesel cycle engine utilizing turbine (jet) fuel. The applicable airworthiness regulations do not contain adequate......

  14. Ice storage rooftop retrofit for rooftop air conditioning

    SciTech Connect

    Tomlinson, J.J.; Jennings, L.W.

    1997-09-01

    A significant fraction of the floor space in commercial and federal buildings is cooled by single-package rooftop air conditioning units. These units are located on flat roofs and usually operate during the day under hot conditions. They are usually less energy efficient than a chiller system for building cooling. Several U.S. companies are developing systems that employ ice storage in conjunction with chillers to replace older, inefficient rooftop units for improved performance and minimal use of on-peak electricity. Although the low evaporator temperatures needed for ice making tend to reduce the efficiency of the chiller, the overall operating costs of the ice storage system may be lower than that of a packaged, conventional rooftop installation. One version of this concept, the Roofberg{reg_sign} System developed by the Calmac Corporation, was evaluated on a small building at Oak Ridge National Laboratory in Oak Ridge, Tennessee. The Roofberg system consists of a chiller, an ice storage tank, and one or more rooftop units whose evaporator coils have been adapted to use a glycol solution for cooling. The ice storage component decouples the cooling demand of the building from the operation of the chiller. Therefore, the chiller can operate at night (cooler, more efficient condensing temperatures) to meet a daytime cooling demand. This flexibility permits a smaller chiller to satisfy a larger peak cooling load. Further, the system can be operated to shift the cooling demand to off-peak hours when electricity from the utility is generated more efficiently and at lower cost. This Roofberg system was successfully installed last year on a small one-story office building in Oak Ridge and is currently being operated to cool the building. The building and system were sufficiently instrumented to allow a determination of the performance and efficiency of the Roofberg system. Although the energy efficiency of a simulated Roofberg storage/chiller concept operating in the

  15. Forecasting Future Sea Ice Conditions in the MIZ: a Lagrangian Approach

    NASA Astrophysics Data System (ADS)

    Tremblay, B.; Newton, R.; de Repentigny, P.; Pfirman, S. L.; Meier, W.; Campbell, G. G.

    2014-12-01

    Significant changes in Arctic sea ice extent have been observed in recent years, particularly at the end of the summer. Climate models that have a reasonable late 20th century Arctic climate, forecast ice-free summers in the Arctic before the end of this century. While these models agree on the decline of sea ice extent and the likelihood of a largely seasonal Arctic sea ice cover, the pattern of the sea ice loss and marginal ice zone locations predicted by different models varies widely. Narrowing the uncertainty implicit in these model disagreements is an important contribution to the accuracy of global climate projections. To this end we track the boundary between first and multi-year ice (i.e. the minimum September sea-ice edge position) using Lagrangian back and forward trajectories in both the instrumental record and GCMs participating in the IPCC-AR5. We use the trajectories to quantify the magnitude and interannual variability in the thermodynamic and dynamic (ice export) ice loss, the amount and geographical distribution of multiyear ice melt and first year promotion to second year ice. Results clearly highlight the importance of pre-conditioning (previous winter ice export) on the following summer minimum ice extent. Assessing whether climate models reproduce the correct dynamics of the MIZ can increase our confidence in climate forecasts.

  16. An optimization method for condition based maintenance of aircraft fleet considering prognostics uncertainty.

    PubMed

    Feng, Qiang; Chen, Yiran; Sun, Bo; Li, Songjie

    2014-01-01

    An optimization method for condition based maintenance (CBM) of aircraft fleet considering prognostics uncertainty is proposed. The CBM and dispatch process of aircraft fleet is analyzed first, and the alternative strategy sets for single aircraft are given. Then, the optimization problem of fleet CBM with lower maintenance cost and dispatch risk is translated to the combinatorial optimization problem of single aircraft strategy. Remain useful life (RUL) distribution of the key line replaceable Module (LRM) has been transformed into the failure probability of the aircraft and the fleet health status matrix is established. And the calculation method of the costs and risks for mission based on health status matrix and maintenance matrix is given. Further, an optimization method for fleet dispatch and CBM under acceptable risk is proposed based on an improved genetic algorithm. Finally, a fleet of 10 aircrafts is studied to verify the proposed method. The results shows that it could realize optimization and control of the aircraft fleet oriented to mission success.

  17. Modelling of Kealey ice rise, Antarctica, reveals stable ice-flow conditions in East Ellsworth Land over millennia

    NASA Astrophysics Data System (ADS)

    Martin, Carlos; Hilmar Gudmundsson, G.

    2013-04-01

    Ice divides are dynamical features, and their evolution or stability reflects the conditions of the surrounding ice masses. The East of Ellsworth Land, West Antarctic Ice Sheet, is ringed by divides showing linear features parallel to the ridge in satellite imagery and a conspicuous layering in the ground-penetrating radar data known as Raymond bumps. These features have been shown to be the result of stability over a time-scale comparable to the characteristic time of the divide, ice thickness divided by accumulation, that varies between centuries and millennia in this area. In this study, we focus in Kealey ice rise, an ice divide situated between two distributaries of Rutford ice stream, Carlson and Talutis Inlets.Through numerical modelling, by using an anisotropic full-Stokes thermomechanical flow solver, we analyze the stability of Kealey ice rise and the time-scales involved. We show that our modelling approach can reproduce the radar data only if we use a non-linear anisotropic rheology, and that the asymmetry observed in radar data is forced mainly by the topography of the bedrock. We conclude that the features observed in the surface and stratigraphy of Kealey ice rise are a consequence of, at least, 5 kyr of flow regime stability. However, we can not exclude the possibility of a recent flow reorganization in the last century that could only be reflected in the shallower areas of the ice rise. We stress that the signs of stability observed in Kealey Ice Rise are widespread in the Ellsworth Land area, suggesting recent stability on the millennium time-scale.

  18. Examination Of A Strong Downslope Warming Wind Event Over The Larsen Ice Shelf In Antarctica Through Modeling And Aircraft Observations

    NASA Astrophysics Data System (ADS)

    Grosvenor, D. P.; Choularton, T. W.; Gallagher, M. W.; Lachlan-Cope, T. A.; King, J. C.

    2009-12-01

    The high mountains of the Antarctic Peninsula (AP) provide a climatic barrier between the west and east. The east side is generally blocked from the warmer oceanic air of the west and is consequently usually under the influence of colder continental air. On occasion, however, air from the west can cross the barrier in the form of strong winds travelling down the eastern slopes, which are also very warm and dry due to adiabatic descent. They penetrate onto the Larsen ice shelves where they lead to above zero surface temperatures and are therefore likely to encourage surface melting. Crevasse propagation due to the weight of accumulated meltwater is currently thought to have been the major factor in causing the near total disintegration of the Larsen B ice shelf in 2002. In January 2006 the British Antarctic Survey performed an aircraft flight over the Larsen C ice shelf on the east side of the AP, which sampled a strong downslope wind event. Surface flux measurements over the ice shelf suggest that the sensible heat provided by the warm jets would be likely to be negated by latent heat losses from ice ablation. The main cause of any ice melting was likely to be due to shortwave radiation input. However, the warming from the jets is still likely to be important by acting as an on/off control for melting by keeping air temperatures above zero. In addition, the dryness of the winds is likely to prevent cloud cover and thus maximize exposure of the ice shelf to solar energy input. This case study has been modeled using the WRF mesoscale model. The model reproduces the strong downslope winds seen by the aircraft with good comparisons of wind speed and temperature profiles through the wind jets. Further comparisons to surface station data have allowed progress towards achieving the best set up of the model for this case. The modeling agrees with the results of the aircraft study in suggesting that solar radiation input is likely to provide the largest amount of energy for

  19. Measured performance of the heat exchanger in the NASA icing research tunnel under severe icing and dry-air conditions

    NASA Technical Reports Server (NTRS)

    Olsen, W.; Vanfossen, J.; Nussle, R.

    1987-01-01

    Measurements were made of the pressure drop and thermal perfomance of the unique refrigeration heat exchanger in the NASA Lewis Icing Research Tunnel (IRT) under severe icing and frosting conditions and also with dry air. This data will be useful to those planning to use or extend the capability of the IRT and other icing facilities (e.g., the Altitude Wind Tunnel-AWT). The IRT heat exchanger and refrigeration system is able to cool air passing through the test section down to at least a total temperature of -30 C (well below icing requirements), and usually up to -2 C. The system maintains a uniform temperature across the test section at all airspeeds, which is more difficult and time consuming at low airspeeds, at high temperatures, and on hot, humid days when the cooling towers are less efficient. The very small surfaces of the heat exchanger prevent any icing cloud droplets from passing through it and going through the tests section again. The IRT heat exchanger was originally designed not to be adversely affected by severe icing. During a worst-case icing test the heat exchanger iced up enough so that the temperature uniformaity was no worse than about +/- 1 deg C. The conclusion is that the heat exchanger design performs well.

  20. Reconstruction of historic sea ice conditions in a sub-Arctic lagoon

    USGS Publications Warehouse

    Petrich, Chris; Tivy, Adrienne C.; Ward, David H.

    2014-01-01

    Historical sea ice conditions were reconstructed for Izembek Lagoon, Bering Sea, Alaska. This lagoon is a crucial staging area during migration for numerous species of avian migrants and a major eelgrass (Zostera marina) area important to a variety of marine and terrestrial organisms, especially Pacific Flyway black brant geese (Branta bernicla nigricans). Ice cover is a common feature of the lagoon in winter, but appears to be declining, which has implications for eelgrass distribution and abundance, and its use by wildlife. We evaluated ice conditions from a model based on degree days, calibrated to satellite observations, to estimate distribution and long-term trends in ice conditions in Izembek Lagoon. Model results compared favorably with ground observations and 26 years of satellite data, allowing ice conditions to be reconstructed back to 1943. Specifically, periods of significant (limited access to eelgrass areas) and severe (almost complete ice coverage of the lagoon) ice conditions could be identified. The number of days of severe ice within a single season ranged from 0 (e.g., 2001) to ≥ 67 (e.g., 2000). We detected a slight long-term negative trend in ice conditions, superimposed on high inter-annual variability in seasonal aggregate ice conditions. Based on reconstructed ice conditions, the seasonally cumulative number of significant or severe ice days correlated linearly with mean air temperature from January until March. Further, air temperature at Izembek Lagoon was correlated with wind direction, suggesting that ice conditions in Izembek Lagoon were associated with synoptic-scale weather patterns. Methods employed in this analysis may be transferable to other coastal locations in the Arctic.

  1. Atmospheric ice crystals over complex terrain: Pure ice cloud conditions observed in CLACE2013 at Jungfraujoch, Switzerland

    NASA Astrophysics Data System (ADS)

    Schlenczek, Oliver; Fugal, Jacob P.; Bower, Keith N.; Crosier, Jonathan; Flynn, Michael J.; Henneberger, Jan; Krieger, Ulrich K.; Lloyd, Gary; Borrmann, Stephan

    2015-04-01

    The CLACE2013 field campaign took place in January and February 2013 at the High Alpine Research Station, Jungfraujoch, in Switzerland. During this field campaign some events of atmospheric ice crystals in the absence of supercooled water droplets were observed. These included precipitation events from a cloud above and also ice crystals which likely formed in-situ under ice supersaturated conditions similar to "diamond-dust" events. From each event, approx. 1 hour of holographic measurements has been analysed (~1800 images with a 36x24x350 mm3 or ~0.3 L sample volume each). Ice crystals are detected and classified according to their shape to distinguish between different particle habit classes (e.g. columns and needles, plates, irregular crystals) and with this method, drifting snow and ice particles formed in-situ can be distinguished to a certain degree. The major axis length of detected ice particles varied between some tens of microns up to a few millimetres. Size distributions will be shown partitioned by crystal habit. Preliminary results show these ice particles appear similar to diamond dust events observed in Antarctica. For clarification of the meteorological conditions, we use the meteorological parameters from several instruments measured at the site as well as data from additional cloud hydrometeor probes and a ceilometer.

  2. Part A: Cirrus ice crystal nucleation and growth. Part B: Automated analysis of aircraft ice particle data

    NASA Technical Reports Server (NTRS)

    Arnott, William P.; Hallett, John; Hudson, James G.

    1995-01-01

    Specific measurement of cirrus crystals by aircraft and temperature modified CN are used to specify measurements necessary to provide a basis for a conceptual model of cirrus particle formation. Key to this is the ability to measure the complete spectrum of particles at cirrus levels. The most difficult regions for such measurement is from a few to 100 microns, and uses a replicator. The details of the system to automate replicator data analysis are given, together with an example case study of the system provided from a cirrus cloud in FIRE 2, with particles detectable by replicator and FSSP, but not 2DC.

  3. Ground-Based Icing Condition Remote Sensing System Definition

    NASA Technical Reports Server (NTRS)

    Reehorst, Andrew L.; Koenig, George G.

    2001-01-01

    This report documents the NASA Glenn Research Center activities to assess and down select remote sensing technologies for the purpose of developing a system capable of measuring icing condition hazards aloft. The information generated by such a remote sensing system is intended for use by the entire aviation community, including flight crews. air traffic controllers. airline dispatchers, and aviation weather forecasters. The remote sensing system must be capable of remotely measuring temperature and liquid water content (LWC), and indicating the presence of super-cooled large droplets (SLD). Technologies examined include Profiling Microwave Radiometer, Dual-Band Radar, Multi-Band Radar, Ka-Band Radar. Polarized Ka-Band Radar, and Multiple Field of View (MFOV) Lidar. The assessment of these systems took place primarily during the Mt. Washington Icing Sensors Project (MWISP) in April 1999 and the Alliance Icing Research Study (AIRS) from November 1999 to February 2000. A discussion of the various sensing technologies is included. The result of the assessment is that no one sensing technology can satisfy all of the stated project goals. Therefore a proposed system includes radiometry and Ka-band radar. A multilevel approach is proposed to allow the future selection of the fielded system based upon required capability and available funding. The most basic level system would be the least capable and least expensive. The next level would increase capability and cost, and the highest level would be the most capable and most expensive to field. The Level 1 system would consist of a Profiling Microwave Radiometer. The Level 2 system would add a Ka-Band Radar. The Level 3 system would add polarization to the Ka-Band Radar. All levels of the system would utilize hardware that is already under development by the U.S. Government. However, to meet the needs of the aviation community, all levels of the system will require further development. In addition to the proposed system

  4. Five Year Changes in Surface Elevations Of The Greenland Ice Sheet Measured by Aircraft Laser Altimetry

    NASA Technical Reports Server (NTRS)

    Krabill, W. B.; Frederick, E. B.; Manizade, S. M.; Martin, C. F.; Sonntag, J. G.; Swift, R. N.; Thomas, R. H.; Wright, C. W.; Yungel, J. K.

    2000-01-01

    The Arctic Ice Mapping group (Project AIM) at NASA's Wallops Flight Facility has been conducting systematic topographic surveys of the Greenland Ice Sheet since 1993, using scanning airborne laser altimeters combined with GPS positioning technology. Flight lines were planned to cover all major ice drainage basins, with the intention to repeat the surveys after a 5-year interval in order to detect changes in the ice-sheet volume. The first resurvey was completed in June/July, 1998, along flight lines in the southern half of Greenland which had been first surveyed in 1993. The northern half of the ice sheet will be resurveyed in 1999. The resulting data sets will provide the first comprehensive examination of regional changes in the the surface elevation of the World's second largest ice sheet. This analysis includes the ice sheet fringe areas, which are expected to be much more climatically sensitive than the interior. Data will be presented which demonstrate the combination of the ATM (Airborne Topographic Mapper) sensors and GPS (Global Positioning System) yields measurements which are repeatable at the 10 cm level over baselines in excess of 1000 km.

  5. Winter Observations of Platelet Ice Growth and Oceanographic Conditions in McMurdo Sound, Antarctica

    NASA Astrophysics Data System (ADS)

    Leonard, G.; Purdie, C.; Langhorne, P.; Haskell, T.; Williams, M.; Vennell, R.

    2004-05-01

    Almost all that is known about sea ice growing attached to the Antarctic landmass has been measured in the spring and summer when the sea ice has grown to over 1~m thick. Platelet ice is the name given to ice crystals that nucleate in the ocean and grow either at depth in the sea water or loosely attached to the ice water interface. It appears to form in sea water cooled below its freezing point, and was first observed in McMurdo Sound by scientists of Scott's Discovery Expedition of 1901{\\textendash}1904. It is known that the formation of platelet ice is linked to the proximity of ice shelves, however the exact freezing mechanism is a matter of some conjecture. In this study we have spent the winter months (February{\\textendash}September) 2003 on the sea ice in McMurdo Sound simultaneously measuring ice and oceanographic conditions in order to increase our understanding of platelet ice formation. Early results indicate the presence of a relatively warm water layer in April which has been replaced by a stable mixed layer by June, with periodic episodes of cold water intrusions into the mixed layer. The water near the ice - water interface was found to be consistently supercooled from July onwards. Platelet growth was observed to be episodic and correlated with times of low tidal flow. Ice coring data reveals that the first layer of platelet ice incorporated into the sea ice sheet did not appear until the ice was around 0.7~m thick, even though platelet ice was observed on foreign bodies in the water column when the ice was significantly thinner.

  6. Over Ice

    NASA Video Gallery

    All about NASA's IceBridge P-3B plane and its IceBridge retrofit. Upgraded with 21st century "special modifications", the aircraft is less a cold war relic and more like the Space Agency's Millenni...

  7. Extrapolating Ground-Based Aircraft Engine Exhaust Emissions to Cruise Conditions: Lessons From the 2013 ACCESS Chase Plane Experiment

    NASA Astrophysics Data System (ADS)

    Moore, R.; Shook, M.; Thornhill, K. L.; Winstead, E.; Anderson, B. E.

    2011-12-01

    Aircraft engine emissions constitute a tiny fraction of the global black carbon mass, but can have a disproportionate climatic impact because they are emitted high in the troposphere and in remote regions with otherwise low aerosol concentrations. Consequently, these particles are likely to strongly influence cirrus and contrail formation by acting as ice nuclei (IN). However, the ice nucleating properties of aircraft exhaust at relevant atmospheric conditions are not well known, and thus, the overall impact of aviation on cloud formation remains very uncertain. While a number of aircraft engine emissions studies have previously been conducted at sea level temperature and pressure (e.g., APEX, AAFEX-1 and 2), it unclear the extent to which exhaust emissions on the ground translate to emissions at cruise conditions with much lower inlet gas temperatures and pressures. To address this need, the NASA Alternative Fuel Effects on Contrails and Cruise Emissions (ACCESS) was conducted in February-April, 2013 to examine the aerosol and gas emissions from the NASA DC-8 under a variety of different fuel types, engine power, and altitude/meteorological conditions. Two different fuel types were studied: a traditional JP-8 fuel and a 50:50 blend of JP-8 and a camelina-based hydro-treated renewable jet (HRJ) fuel. Emissions were sampled using a comprehensive suite of gas- and aerosol-phase instrumentation integrated on an HU-25 Falcon jet that was positioned in the DC-8 exhaust plume at approximately 100-500m distance behind the engines. In addition, a four-hour ground test was carried out with sample probes positioned at 30 m behind each of the inboard engines. Measurements of aerosol concentration, size distribution, soot mass, and hygroscopicity were carried out along with trace gas measurements of CO2, NO, NO2, O3, and water vapor. NOx emissions were reconciled by employing the well-established Boeing method for normalizing engine fuel flow rates to STP; however, comparison

  8. Extrapolating Ground-Based Aircraft Engine Exhaust Emissions to Cruise Conditions: Lessons From the 2013 ACCESS Chase Plane Experiment

    NASA Astrophysics Data System (ADS)

    Moore, R.; Shook, M.; Thornhill, K. L.; Winstead, E.; Anderson, B. E.

    2013-12-01

    Aircraft engine emissions constitute a tiny fraction of the global black carbon mass, but can have a disproportionate climatic impact because they are emitted high in the troposphere and in remote regions with otherwise low aerosol concentrations. Consequently, these particles are likely to strongly influence cirrus and contrail formation by acting as ice nuclei (IN). However, the ice nucleating properties of aircraft exhaust at relevant atmospheric conditions are not well known, and thus, the overall impact of aviation on cloud formation remains very uncertain. While a number of aircraft engine emissions studies have previously been conducted at sea level temperature and pressure (e.g., APEX, AAFEX-1 and 2), it unclear the extent to which exhaust emissions on the ground translate to emissions at cruise conditions with much lower inlet gas temperatures and pressures. To address this need, the NASA Alternative Fuel Effects on Contrails and Cruise Emissions (ACCESS) was conducted in February-April, 2013 to examine the aerosol and gas emissions from the NASA DC-8 under a variety of different fuel types, engine power, and altitude/meteorological conditions. Two different fuel types were studied: a traditional JP-8 fuel and a 50:50 blend of JP-8 and a camelina-based hydro-treated renewable jet (HRJ) fuel. Emissions were sampled using a comprehensive suite of gas- and aerosol-phase instrumentation integrated on an HU-25 Falcon jet that was positioned in the DC-8 exhaust plume at approximately 100-500m distance behind the engines. In addition, a four-hour ground test was carried out with sample probes positioned at 30 m behind each of the inboard engines. Measurements of aerosol concentration, size distribution, soot mass, and hygroscopicity were carried out along with trace gas measurements of CO2, NO, NO2, O3, and water vapor. NOx emissions were reconciled by employing the well-established Boeing method for normalizing engine fuel flow rates to STP; however, comparison

  9. Microbial activity in debris-rich basal ice; adaption to sub-zero, saline conditions

    NASA Astrophysics Data System (ADS)

    Montross, S. N.; Skidmore, M. L.; Christner, B. C.; Griggs, R.; Tison, J.; Sowers, T. A.

    2011-12-01

    Polycrystalline ice in glaciers and ice sheets has a high preservation potential for biological material and chemical compounds that can be used to document the presence of active microbial metabolism at sub-zero temperatures. The concentration and isotopic composition of gases, in conjunction with other aqueous chemical species in debris-rich basal glacier ice from Taylor Glacier, Antarctica were used as direct evidence that cells entrained in the ice remain metabolically active at temperatures as low as -17°C, likely in thin films of liquid water along ice crystal and mineral grain boundaries. δ18O2 and δ13CO2 values measured in the ice are consistent with the hypothesis that abrupt changes measured in O2 and CO2 concentrations between debris-rich and debris-poor ice are due to in situ microbial mineralization of organic carbon. Low temperature culture-based experiments conducted using organisms isolated from the ice indicate the ability to respire organic carbon to CO2 under oxic conditions and under anoxic conditions couple carbon mineralization to dissimilatory iron reduction using Fe3+ as an electron acceptor. Microorganisms that are active in the debris-rich basal ice layers in terrestrial polar ice masses need to be adapted to surviving subzero temperatures and saline conditions on extended timescales. Thus these terrestrial glacial systems and the isotopic and geochemical biomarkers therein provide good analogues for guiding exploration and analysis of debris-rich ices in extraterrestrial settings, for example, on Mars.

  10. Air Force F-16 Aircraft Engine Aerosol Emissions Under Cruise Altitude Conditions

    NASA Technical Reports Server (NTRS)

    Anderson, Bruce E.; Cofer, W. Randy, III; McDougal, David S.

    1999-01-01

    Selected results from the June 1997 Third Subsonic Assessment Near-Field Interactions Flight (SNIF-III) Experiment are documented. The primary objectives of the SNIF-III experiment were to determine the partitioning and abundance of sulfur species and to examine the formation and growth of aerosol particles in the exhaust of F-16 aircraft as a function of atmospheric and aircraft operating conditions and fuel sulfur concentration. This information is, in turn, being used to address questions regarding the fate of aircraft fuel sulfur impurities and to evaluate the potential of their oxidation products to perturb aerosol concentrations and surface areas in the upper troposphere. SNIF-III included participation of the Vermont and New Jersey Air National Guard F-16's as source aircraft and the Wallops Flight Facility T-39 Sabreliner as the sampling platform. F-16's were chosen as a source aircraft because they are powered by the modern F-100 Series 220 engine which is projected to be representative of future commercial aircraft engine technology. The T-39 instrument suite included sensors for measuring volatile and non-volatile condensation nuclei (CN), aerosol size distributions over the range from 0.1 to 3.0 (micro)m, 3-D winds, temperature, dewpoint, carbon dioxide (CO2), sulfur dioxide (SO2), sulfuric acid (H2SO4), and nitric acid (HNO3).

  11. Structural tailoring of aircraft engine blade subject to ice impact constraints

    NASA Technical Reports Server (NTRS)

    Reddy, E. S.; Abumeri, G. H.; Murthy, P. L. N.; Chamis, C. C.

    1993-01-01

    Results are presented for the minimum weight design of SR2 unswept blade made of (titanium/graphite-epoxy/titanium) sub s fiber composite. The blade which is rotating at high RPM is subject to ice impact. The root chord length, blade thicknesses at five stations, and graphite-epoxy ply orientation are chosen as design variables. Design constraints are placed on the behavior variables: local leading edge strain and root damage parameter (combined stress failure criteria) as a function due to ice impact, maximum spanwise centrifugal stress at the root of the deformed blade due to local damage, first three natural frequencies, and resonance margin after impact. The method of feasible directions is employed to solve the inequality constrained minimization problem. The effect of ice speed and the ice impact location on the final design are discussed.

  12. Aircraft Abnormal Conditions Detection, Identification, and Evaluation Using Innate and Adaptive Immune Systems Interaction

    NASA Astrophysics Data System (ADS)

    Al Azzawi, Dia

    Abnormal flight conditions play a major role in aircraft accidents frequently causing loss of control. To ensure aircraft operation safety in all situations, intelligent system monitoring and adaptation must rely on accurately detecting the presence of abnormal conditions as soon as they take place, identifying their root cause(s), estimating their nature and severity, and predicting their impact on the flight envelope. Due to the complexity and multidimensionality of the aircraft system under abnormal conditions, these requirements are extremely difficult to satisfy using existing analytical and/or statistical approaches. Moreover, current methodologies have addressed only isolated classes of abnormal conditions and a reduced number of aircraft dynamic parameters within a limited region of the flight envelope. This research effort aims at developing an integrated and comprehensive framework for the aircraft abnormal conditions detection, identification, and evaluation based on the artificial immune systems paradigm, which has the capability to address the complexity and multidimensionality issues related to aircraft systems. Within the proposed framework, a novel algorithm was developed for the abnormal conditions detection problem and extended to the abnormal conditions identification and evaluation. The algorithm and its extensions were inspired from the functionality of the biological dendritic cells (an important part of the innate immune system) and their interaction with the different components of the adaptive immune system. Immunity-based methodologies for re-assessing the flight envelope at post-failure and predicting the impact of the abnormal conditions on the performance and handling qualities are also proposed and investigated in this study. The generality of the approach makes it applicable to any system. Data for artificial immune system development were collected from flight tests of a supersonic research aircraft within a motion-based flight

  13. Experimental study of ice lens formation using fine granular materials under terrestrial and martian conditions

    NASA Astrophysics Data System (ADS)

    Saruya, T.; Rempel, A. W.; Kurita, K.

    2012-12-01

    Detailed exploration of Mars has yielded a range of direct and indirect evidence for the distribution of ice. Significantly, direct observations of segregated ice (i.e. sediment free) were obtained by Phoenix lander. This segregated ice most likely originated as an ice lens, which formed by the migration and solidification of unfrozen water. Unfrozen water that is adsorbed to particle surfaces and confined to capillary regions remains in the liquid state below the normal melting temperature. This water is known to migrate in frozen materials and form ice lenses. Zent et al. (2012) developed a numerical model for ice lens formation (Rempel et al. 2004) and demonstrated that the nucleation of ice lenses at the Phoenix landing site was possible in the recent past. However, many questions remain regarding the detailed conditions of ice lens nucleation and growth, even in the terrestrial environment. Further experimental checks of numerical models are especially needed. Here, we describe laboratory investigations of ice lens behavior under both terrestrial conditions and with experimental conditions approaching those in the martian environment. We have performed a series of step-freezing experiments in fine, granular materials to observe the initiation and growth of ice lenses. Our experiments reveal clear and systematic relationships between ice-lens behavior and the imposed cooling temperature and host particle size. We compared our experimental results to numerical predictions from a model of ice lens formation (Rempel et al. 2004) that was applied to our experimental conditions. We find that the trend is consistent between the experiment and model, however, there are important quantitative differences. Most notably, modeled ice-lens nucleation occurred more quickly and enabled ice lenses to grow larger than occurred during our experiments. We infer that some additional mechanisms must be responsible for restricting the formation and growth of ice lenses. Further

  14. Laser-induced plasma cloud interaction and ice multiplication under cirrus cloud conditions.

    PubMed

    Leisner, Thomas; Duft, Denis; Möhler, Ottmar; Saathoff, Harald; Schnaiter, Martin; Henin, Stefano; Stelmaszczyk, Kamil; Petrarca, Massimo; Delagrange, Raphaëlle; Hao, Zuoqiang; Lüder, Johannes; Petit, Yannick; Rohwetter, Philipp; Kasparian, Jérôme; Wolf, Jean-Pierre; Wöste, Ludger

    2013-06-18

    Potential impacts of lightning-induced plasma on cloud ice formation and precipitation have been a subject of debate for decades. Here, we report on the interaction of laser-generated plasma channels with water and ice clouds observed in a large cloud simulation chamber. Under the conditions of a typical storm cloud, in which ice and supercooled water coexist, no direct influence of the plasma channels on ice formation or precipitation processes could be detected. Under conditions typical for thin cirrus ice clouds, however, the plasma channels induced a surprisingly strong effect of ice multiplication. Within a few minutes, the laser action led to a strong enhancement of the total ice particle number density in the chamber by up to a factor of 100, even though only a 10(-9) fraction of the chamber volume was exposed to the plasma channels. The newly formed ice particles quickly reduced the water vapor pressure to ice saturation, thereby increasing the cloud optical thickness by up to three orders of magnitude. A model relying on the complete vaporization of ice particles in the laser filament and the condensation of the resulting water vapor on plasma ions reproduces our experimental findings. This surprising effect might open new perspectives for remote sensing of water vapor and ice in the upper troposphere.

  15. Laser-induced plasma cloud interaction and ice multiplication under cirrus cloud conditions

    PubMed Central

    Leisner, Thomas; Duft, Denis; Möhler, Ottmar; Saathoff, Harald; Schnaiter, Martin; Henin, Stefano; Stelmaszczyk, Kamil; Petrarca, Massimo; Delagrange, Raphaëlle; Hao, Zuoqiang; Lüder, Johannes; Petit, Yannick; Rohwetter, Philipp; Kasparian, Jérôme; Wolf, Jean-Pierre; Wöste, Ludger

    2013-01-01

    Potential impacts of lightning-induced plasma on cloud ice formation and precipitation have been a subject of debate for decades. Here, we report on the interaction of laser-generated plasma channels with water and ice clouds observed in a large cloud simulation chamber. Under the conditions of a typical storm cloud, in which ice and supercooled water coexist, no direct influence of the plasma channels on ice formation or precipitation processes could be detected. Under conditions typical for thin cirrus ice clouds, however, the plasma channels induced a surprisingly strong effect of ice multiplication. Within a few minutes, the laser action led to a strong enhancement of the total ice particle number density in the chamber by up to a factor of 100, even though only a 10−9 fraction of the chamber volume was exposed to the plasma channels. The newly formed ice particles quickly reduced the water vapor pressure to ice saturation, thereby increasing the cloud optical thickness by up to three orders of magnitude. A model relying on the complete vaporization of ice particles in the laser filament and the condensation of the resulting water vapor on plasma ions reproduces our experimental findings. This surprising effect might open new perspectives for remote sensing of water vapor and ice in the upper troposphere. PMID:23733936

  16. Laser-induced plasma cloud interaction and ice multiplication under cirrus cloud conditions.

    PubMed

    Leisner, Thomas; Duft, Denis; Möhler, Ottmar; Saathoff, Harald; Schnaiter, Martin; Henin, Stefano; Stelmaszczyk, Kamil; Petrarca, Massimo; Delagrange, Raphaëlle; Hao, Zuoqiang; Lüder, Johannes; Petit, Yannick; Rohwetter, Philipp; Kasparian, Jérôme; Wolf, Jean-Pierre; Wöste, Ludger

    2013-06-18

    Potential impacts of lightning-induced plasma on cloud ice formation and precipitation have been a subject of debate for decades. Here, we report on the interaction of laser-generated plasma channels with water and ice clouds observed in a large cloud simulation chamber. Under the conditions of a typical storm cloud, in which ice and supercooled water coexist, no direct influence of the plasma channels on ice formation or precipitation processes could be detected. Under conditions typical for thin cirrus ice clouds, however, the plasma channels induced a surprisingly strong effect of ice multiplication. Within a few minutes, the laser action led to a strong enhancement of the total ice particle number density in the chamber by up to a factor of 100, even though only a 10(-9) fraction of the chamber volume was exposed to the plasma channels. The newly formed ice particles quickly reduced the water vapor pressure to ice saturation, thereby increasing the cloud optical thickness by up to three orders of magnitude. A model relying on the complete vaporization of ice particles in the laser filament and the condensation of the resulting water vapor on plasma ions reproduces our experimental findings. This surprising effect might open new perspectives for remote sensing of water vapor and ice in the upper troposphere. PMID:23733936

  17. Driving Stresses in Mars Polar Ice Caps and Conditions for Ice Flow

    NASA Technical Reports Server (NTRS)

    Zwally, H. Jay; Saba, Jack L.

    1999-01-01

    Measurements of the topography of the North polar ice cap by the Mars Orbiter Laser Altimeter (MOLA) show that the ice cap is 2950 +/- 200 meters thick. The volume of the cap is about 1.2 x 10(exp 6) cu km covering an area of 1.04 x 10(exp 6) sq km, which is about 40 percent of the Greenland ice sheet in volume and 62 percent in area. The composition of the Northern cap was previously concluded to be predominately H2O, rather than CO2 ice, based on thermodynamic considerations of the insustainablity of CO2 during summer. Principal questions about the cap are: does the ice move and at what rate, is the cap currently growing or depleting in volume, and how and when was the cap formed? Recent research on terrestrial ice sheets indicates that rates of ice deformation at the low stress values characteristic of ice sheets are significantly higher than the rates given by the classic viscous-plastic flow laws commonly used.

  18. A tale of two polar bear populations: Ice habitat, harvest, and body condition

    USGS Publications Warehouse

    Rode, K.D.; Peacock, E.; Taylor, M.; Stirling, I.; Born, E.W.; Laidre, K.L.; Wiig, O.

    2012-01-01

    One of the primary mechanisms by which sea ice loss is expected to affect polar bears is via reduced body condition and growth resulting from reduced access to prey. To date, negative effects of sea ice loss have been documented for two of 19 recognized populations. Effects of sea ice loss on other polar bear populations that differ in harvest rate, population density, and/or feeding ecology have been assumed, but empirical support, especially quantitative data on population size, demography, and/or body condition spanning two or more decades, have been lacking. We examined trends in body condition metrics of captured bears and relationships with summertime ice concentration between 1977 and 2010 for the Baffin Bay (BB) and Davis Strait (DS) polar bear populations. Polar bears in these regions occupy areas with annual sea ice that has decreased markedly starting in the 1990s. Despite differences in harvest rate, population density, sea ice concentration, and prey base, polar bears in both populations exhibited positive relationships between body condition and summertime sea ice cover during the recent period of sea ice decline. Furthermore, females and cubs exhibited relationships with sea ice that were not apparent during the earlier period (1977-1990s) when sea ice loss did not occur. We suggest that declining body condition in BB may be a result of recent declines in sea ice habitat. In DS, high population density and/or sea ice loss, may be responsible for the declines in body condition. ?? 2011 The Society of Population Ecology and Springer.

  19. Theoretical analysis of the electrical aspects of the basic electro-impulse problem in aircraft de-icing applications

    NASA Technical Reports Server (NTRS)

    Henderson, Robert A.; Schrag, Robert L.

    1987-01-01

    A method of modelling a system consisting of a cylindrical coil with its axis perpendicular to a metal plate of finite thickness, and a simple electrical circuit for producing a transient current in the coil, is discussed in the context of using such a system for de-icing aircraft surfaces. A transmission line model of the coil and metal plate is developed as the heart of the system model. It is shown that this transmission model is central to calculation of the coil impedance, the coil current, the magnetic fields established on the surfaces of the metal plate, and the resultant total force between the coil and the plate. FORTRAN algorithms were developed for numerical calculation of each of these quantities, and the algorithms were applied to an experimental prototype system in which these quantities had been measured. Good agreement is seen to exist between the predicted and measured results.

  20. An efficient finite element method for aircraft de-icing problems

    NASA Technical Reports Server (NTRS)

    Huang, J. R.; Keith, Theo G., Jr.; De Witt, Kenneth J.

    1992-01-01

    In this paper, a finite element formulation based on an assumed states method is proposed for the solution of heat conduction problems with phase change at a fixed temperature. Attention is directed toward reduction of computer cost through the use of an efficient formulation, solver and algorithm. The procedure is applied to the analysis of an electrothermally deiced aircraft surface.

  1. Parameterization and scaling of arctic ice conditions in the context of ice-atmospheric processes

    NASA Technical Reports Server (NTRS)

    Barry, R. G.; Steffen, K.; Heinrichs, J. F.; Key, J. R.; Maslanik, J. A.; Serreze, M. C.; Weaver, R. L.

    1995-01-01

    The goals of this project are to observe how the open water/thin ice fraction in a high-concentration ice pack responds to different short-period atmospheric forcings, and how this response is represented in different scales of observation. The objectives can be summarized as follows: determine the feasibility and accuracy of ice concentration and ice typing by ERS-1 SAR backscatter data, and whether SAR data might be used to calibrate concentration estimates from optical and massive-microwave sensors; investigate methods to integrate SAR data with other satellite data for turbulent heat flux parameterization at the ocean/atmosphere interface; determine how the development and evolution of open water/thin ice areas within the interior ice pack vary under different atmospheric synoptic regimes; compare how open-water/thin ice fractions estimated from large-area divergence measurements differ from fractions determined by summing localized openings in the pack; relate these questions of scale and process to methods of observation, modeling, and averaging over time and space.

  2. Ice Prevention on Aircraft by Means of Impregnated Leather Covers, Special Report

    NASA Technical Reports Server (NTRS)

    Clay, William C.

    1935-01-01

    The National Advisory Committee for Aeronautics is testing the effectiveness of a method to prevent the formation of ice on airplanes. The system makes use of a leather cover that is attached to the leading edge of the wing. A small tube, attached to the inner surface of the leather, distributes to the leading edge a solution that permeates throughout the leather and inhibits the formation of ice on the surface. About 25 pounds of the liquid per hour would be sufficient to prevent ice from forming on a wing of 50-foot span. The additional gross weight of the system will not be excessive. The tests are not yet completed but the method is thought to be practicable for the wing and it may also be adaptable to the propeller.

  3. NASA's Operation IceBridge: using instrumented aircraft to bridge the observational gap between ICESat and ICESat-2 laser altimeter measurements (Invited)

    NASA Astrophysics Data System (ADS)

    Studinger, M.; Koenig, L.; Martin, S.; Sonntag, J. G.

    2010-12-01

    In 2009, the NASA satellite laser altimeter mission ICESat (Ice, Cloud and Land Elevation Satellite), which was launched in 2003, ceased to operate. To bridge the gap in polar laser observations between ICESat and its replacement ICESat-2, which is not scheduled for launch until 2015, Operation IceBridge, a six-year NASA airborne mission, was initiated in 2009. From a series of yearly polar flights, Operation IceBridge uses airborne instruments to map rapidly changing areas in the Arctic and Antarctic, building on two decades of repeat airborne and satellite measurements. Combined with previous aircraft observations, as well as ICESat, CryoSat-2 and the forthcoming ICESat-2 observations, Operation IceBridge will produce a cross-calibrated 17-year time series of ice sheet and sea-ice elevation data over Antarctica, as well as a 27-year time series over Greenland. These time series will be a critical resource for predictive models of sea ice and ice sheet behavior. In addition to laser altimetry, Operation IceBridge is using a comprehensive suite of instruments to produce a three-dimensional view of the Arctic and Antarctic ice sheets, ice shelves and the sea ice. The suite includes two NASA laser altimeters, the Airborne Topographic Mapper (ATM) and the Land, Vegetation and Ice Sensor (LVIS); four radar systems from the University of Kansas’ Center for Remote Sensing of Ice Sheets (CReSIS), a Ku-band radar altimeter, accumulation radar, snow radar and the Multichannel Coherent Radar Depth Sounder (MCoRDS); a Sander Geophysics airborne gravimeter (AIRGrav) and a high resolution stereographic camera (DMS). The first Operation IceBridge flights were conducted between March and May 2009 over the Arctic and between October and November 2009 over Antarctica. Since its start in 2009, Operation IceBridge has flown 69 science missions, 580 flight hours and collected more than 350,000 km of data. All Operation IceBridge data are available at NSDIC: http

  4. 14 CFR 121.341 - Equipment for operations in icing conditions.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... prohibit the flight will not be encountered during the flight because of changed weather conditions since... known or forecast severe icing conditions. (d) If current weather reports and briefing...

  5. Short Term Variation of Cosmic Radiation on Aircraft at Constant Flight Condition

    NASA Astrophysics Data System (ADS)

    Lee, J.; Nam, U. W.; Pyo, J.; Kim, S.; Kwon, Y. J.; Kim, M. H. Y.

    2015-12-01

    The temporal variation of cosmic radiation was measured by Liulin detector on aircraft at constant flight condition. In this experiment, instead of using a commercial aircraft that flies over long distances, we used a military reconnaissance aircraft performing a circular flight over Korean Peninsula. Measurements indicate that the radiation dose is approximately 2.12 ~ 2.88 Sv/hr at 30,000 ft. We obtained two observational results from this experiment. First, changes in dose rate occurred within a flight time of 5 - 7 hours. Second, no strong correlation was revealed between cosmic rays observed from the ground using the Neutron Monitor and the radiation dose. Our experimental results imply that changes in cosmic radiation at the flight altitude are affected by unknown factors that might be investigated in the point of space weather.

  6. Evaluation of two transport aircraft and several ground test vehicle friction measurements obtained for various runway surface types and conditions. A summary of test results from joint FAA/NASA Runway Friction Program

    NASA Technical Reports Server (NTRS)

    Yager, Thomas J.; Vogler, William A.; Baldasare, Paul

    1990-01-01

    Tests with specially instrumented NASA Boeing 737 and 727 aircraft together with several different ground friction measuring devices were conducted for a variety of runway surface types and conditions. These tests are part of joint FAA/NASA Aircraft/Ground Vehicle Runway Friction Program aimed at obtaining a better understanding of aircraft ground handling performance under adverse weather conditions and defining relationships between aircraft and ground vehicle tire friction measurements. Aircraft braking performance on dry, wet, snow and ice-covered runway conditions is discussed as well as ground vehicle friction data obtained under similar runway conditions. For a given contaminated runway surface condition, the correlation between ground vehicles and aircraft friction data is identified. The influence of major test parameters on friction measurements such as speed, test tire characteristics, type and amount of surface contaminant, and ambient temperature are discussed. The effect of surface type on wet friction levels is also evaluated from comparative data collected on grooved and ungrooved concrete and asphalt surfaces.

  7. Parameterization and scaling of Arctic ice conditions in the context of ice-atmosphere processes

    NASA Technical Reports Server (NTRS)

    Barry, R. G.; Heinrichs, J.; Steffen, K.; Maslanik, J. A.; Key, J.; Serreze, M. C.; Weaver, R. W.

    1994-01-01

    This report summarizes achievements during year three of our project to investigate the use of ERS-1 SAR data to study Arctic ice and ice/atmosphere processes. The project was granted a one year extension, and goals for the final year are outlined. The specific objects of the project are to determine how the development and evolution of open water/thin ice areas within the interior ice pack vary under different atmospheric synoptic regimes; compare how open water/thin ice fractions estimated from large-area divergence measurements differ from fractions determined by summing localized openings in the pack; relate these questions of scale and process to methods of observation, modeling, and averaging over time and space; determine whether SAR data might be used to calibrate ice concentration estimates from medium and low-rate bit sensors (AVHRR and DMSP-OLS) and the special sensor microwave imager (SSM/I); and investigate methods to integrate SAR data for turbulent heat flux parametrization at the atmosphere interface with other satellite data.

  8. Preliminary Flight Deck Observations During Flight in High Ice Water Content Conditions

    NASA Technical Reports Server (NTRS)

    Ratvasky, Thomas; Duchanoy, Dominque; Bourdinot, Jean-Francois; Harrah, Steven; Strapp, Walter; Schwarzenboeck, Alfons; Dezitter, Fabien; Grandin, Alice

    2015-01-01

    In 2006, Mason et al. identified common observations that occurred in engine power-loss events attributed to flight in high concentrations of ice crystals. Observations included light to moderate turbulence, precipitation on the windscreen (often reported as rain), aircraft total temperature anomalies, lack of significant airframe icing, and no flight radar echoes at the location and altitude of the engine event. Since 2006, Mason et al. and others have collected information from pilots who experienced engine power-loss events via interviews and questionnaires to substantiate earlier observations and support event analyses. In 2011, Mason and Grzych reported that vertical acceleration data showed increases in turbulence prior to engine events, although the turbulence was usually light to moderate and not unique to high ice water content (HIWC) clouds. Mason concluded that the observation of rain on the windscreen was due to melting of ice high concentrations of ice crystals on the windscreen, coalescing into drops. Mason also reported that these pilot observations of rain on the windscreen were varied. Many pilots indicated no rain was observed, while others observed moderate rain with unique impact sounds. Mason concluded that the variation in the reports may be due to variation in the ice concentration, particle size, and temperature.

  9. ICEPOD - Developing Ice Imaging Capabilities for the New York Air National Guard's LC-130 Aircraft

    NASA Astrophysics Data System (ADS)

    Detemple, J.; Frearson, N.; Zappa, C. J.; Turrin, M.; Bell, R. E.

    2010-12-01

    The ICEPOD program is a 5-year development effort to develop a polar instrumentation suite for the New York Air National Guard’s (NYANG) LC-130’s supported by the NSF American Reinvestment and Recovery Act (ARRA) Major Research Instrumentation program. The fundamental goal of the ICEPOD program is to develop an instrumentation package that can capture the dynamics of the changing polar regions, focusing on ice and ocean targets. The vision is for this instrumentation to be operated both on routine flights of the NYANG in the polar regions, such as missions between McMurdo and South Pole Station and on targeted science missions, such as mapping the sea ice and outlet glaciers surrounding Ross Island or the draining systems from large subglacial lakes in East Antarctica. We are in the process of finalizing the science requirements for the system. To provide support to the ICEPOD development, we are defining the goals for imaging the surface of the ice sheet with a scanning laser system and stereo-photogrammetry, the temperature of the ice surface using an IR camera and the internal structure of the ice sheet using a depth-sounding radar and an accumulation radar. The instrumentation will be positioned using an IMU and differential GPS. We also are working toward two operational modes - low-altitude flight operations to optimize the surface imaging systems, specifically the scanning laser, and a high-altitude flight operation to facilitate wide use of the instrumentation suite during a routine NYANG support mission flight envelope. The ICEPOD program is seeking input on the science goals of the instrumentation suite to ensure the system meets the community’s need for observations. The ultimate goal of the ICEPOD program is to provide the community with a facility for dedicated and routine measurements over the polar regions using the suite of instruments. The final ICEPOD system will also be capable of supporting instrumentation developed by other groups. The

  10. Analysis of the Arctic sea ice conditions for 2011 at the onset of summer minimum

    NASA Astrophysics Data System (ADS)

    Platonov, N. G.; Mordvintsev, I. N.; Rozhnov, V. V.; Alpatsky, I. V.

    2012-12-01

    The summer minimum of the Arctic sea ice area and extent have been estimated for 2011 using satellite passive microwave data. Compared with sea ice conditions during the satellite era (1979 to the present), the Arctic ice cap is close in size to the absolute minimum recorded in 2007. However, the spatial distribution of sea ice at the end of summer differed in 2007 and 2011 due to the atmospheric circulation effect on the position of the ice edge. It is shown that the decreasing rate of the ice cover has increased fourfold since 2003. A linear model has been developed for the global short-term prediction of Arctic ice conditions and historical reconstruction (until the middle of the 20th century, including the pre-satellite era) of summer ice conditions from the air temperature fields using the dimensionality reduction technique (principal component analysis) and canonical correlation analysis. The simulation results confirm the drastic change in the sea ice area at the end of summer after 2002.

  11. 41 CFR 102-37.460 - What special terms and conditions apply to the donation of aircraft and vessels?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... conditions apply to the donation of aircraft and vessels? 102-37.460 Section 102-37.460 Public Contracts and... REGULATION PERSONAL PROPERTY 37-DONATION OF SURPLUS PERSONAL PROPERTY Donations to Public Agencies, Service...-37.460 What special terms and conditions apply to the donation of aircraft and vessels? The...

  12. 41 CFR 102-37.460 - What special terms and conditions apply to the donation of aircraft and vessels?

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... conditions apply to the donation of aircraft and vessels? 102-37.460 Section 102-37.460 Public Contracts and... REGULATION PERSONAL PROPERTY 37-DONATION OF SURPLUS PERSONAL PROPERTY Donations to Public Agencies, Service...-37.460 What special terms and conditions apply to the donation of aircraft and vessels? The...

  13. Numerical modeling investigations of the subglacial conditions of the southern Laurentide ice sheet

    NASA Astrophysics Data System (ADS)

    Bauder, Andreas; Mickelson, David M.; Marshall, Shawn J.

    Sub- and proglacial bed conditions influence advance and retreat of an ice sheet. The existence and distribution of frozen ground is of major importance for better understanding of ice-flow dynamics and landform formation. The southern margin of the Laurentide ice sheet (LIS) was dominated by the presence of relatively thin ice lobes that seem to have been very sensitive to external and internal physical conditions. Their extent and dynamics were highly influenced by the interaction of subglacial and proglacial conditions. A three-dimensional thermomechanical ice-sheet model was coupled with a model for the thermal regime in the upper Earth crust. The model has been applied to the LIS in order to investigate the spatial distribution of thermal conditions at the bed. The evolution of the whole LIS was modeled for the last glacial cycle, with primary attention on correct reconstruction of the southern margin. Our results show extensive temporal and spatial frozen ground conditions. Only a slow degradation of permafrost under the ice was found. We conclude that there are significant interactions between the ice sheet and the underlying frozen ground and that these influence both ice dynamics and landform development.

  14. Regional Arctic sea ice variations as predictor for winter climate conditions

    NASA Astrophysics Data System (ADS)

    Koenigk, Torben; Caian, Mihaela; Nikulin, Grigory; Schimanke, Semjon

    2016-01-01

    Seasonal prediction skill of winter mid and high northern latitudes climate from sea ice variations in eight different Arctic regions is analyzed using detrended ERA-interim data and satellite sea ice data for the period 1980-2013. We find significant correlations between ice areas in both September and November and winter sea level pressure, air temperature and precipitation. The prediction skill is improved when using November sea ice conditions as predictor compared to September. This is particularly true for predicting winter NAO-like patterns and blocking situations in the Euro-Atlantic area. We find that sea ice variations in Barents Sea seem to be most important for the sign of the following winter NAO—negative after low ice—but amplitude and extension of the patterns are modulated by Greenland and Labrador Seas ice areas. November ice variability in the Greenland Sea provides the best prediction skill for central and western European temperature and ice variations in the Laptev/East Siberian Seas have the largest impact on the blocking number in the Euro-Atlantic region. Over North America, prediction skill is largest using September ice areas from the Pacific Arctic sector as predictor. Composite analyses of high and low regional autumn ice conditions reveal that the atmospheric response is not entirely linear suggesting changing predictive skill dependent on sign and amplitude of the anomaly. The results confirm the importance of realistic sea ice initial conditions for seasonal forecasts. However, correlations do seldom exceed 0.6 indicating that Arctic sea ice variations can only explain a part of winter climate variations in northern mid and high latitudes.

  15. 14 CFR 25.1403 - Wing icing detection lights.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Wing icing detection lights. 25.1403... AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Equipment Lights § 25.1403 Wing icing detection lights. Unless operations at night in known or forecast icing conditions are prohibited by...

  16. 14 CFR 25.1403 - Wing icing detection lights.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Wing icing detection lights. 25.1403... AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Equipment Lights § 25.1403 Wing icing detection lights. Unless operations at night in known or forecast icing conditions are prohibited by...

  17. 14 CFR 25.1403 - Wing icing detection lights.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Wing icing detection lights. 25.1403... AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Equipment Lights § 25.1403 Wing icing detection lights. Unless operations at night in known or forecast icing conditions are prohibited by...

  18. Structural health monitoring methodology for aircraft condition-based maintenance

    NASA Astrophysics Data System (ADS)

    Saniger, Jordi; Reithler, Livier; Guedra-Degeorges, Didier; Takeda, Nobuo; Dupuis, Jean Pierre

    2001-06-01

    Reducing maintenance costs while keeping a constant level of safety is a major issue for Air Forces and airlines. The long term perspective is to implement condition based maintenance to guarantee a constant safety level while decreasing maintenance costs. On this purpose, the development of a generalized Structural Health Monitoring System (SHMS) is needed. The objective of such a system is to localize the damages and to assess their severity, with enough accuracy to allow low cost corrective actions. The present paper describes a SHMS based on acoustic emission technology. This choice was driven by its reliability and wide use in the aerospace industry. The described SHMS uses a new learning methodology which relies on the generation of artificial acoustic emission events on the structure and an acoustic emission sensor network. The calibrated acoustic emission events picked up by the sensors constitute the knowledge set that the system relies on. With this methodology, the anisotropy of composite structures is taken into account, thus avoiding the major cause of errors of classical localization methods. Moreover, it is adaptive to different structures as it does not rely on any particular model but on measured data. The acquired data is processed and the event's location and corrected amplitude are computed. The methodology has been demonstrated and experimental tests on elementary samples presented a degree of accuracy of 1cm.

  19. The formation of cubic ice under conditions relevant to Earth's atmosphere.

    PubMed

    Murray, Benjamin J; Knopf, Daniel A; Bertram, Allan K

    2005-03-10

    An important mechanism for ice cloud formation in the Earth's atmosphere is homogeneous nucleation of ice in aqueous droplets, and this process is generally assumed to produce hexagonal ice. However, there are some reports that the metastable crystalline phase of ice, cubic ice, may form in the Earth's atmosphere. Here we present laboratory experiments demonstrating that cubic ice forms when micrometre-sized droplets of pure water and aqueous solutions freeze homogeneously at cooling rates approaching those found in the atmosphere. We find that the formation of cubic ice is dominant when droplets freeze at temperatures below 190 K, which is in the temperature range relevant for polar stratospheric clouds and clouds in the tropical tropopause region. These results, together with heat transfer calculations, suggest that cubic ice will form in the Earth's atmosphere. If there were a significant fraction of cubic ice in some cold clouds this could increase their water vapour pressure, and modify their microphysics and ice particle size distributions. Under specific conditions this may lead to enhanced dehydration of the tropopause region. PMID:15758996

  20. The formation of cubic ice under conditions relevant to Earth's atmosphere.

    PubMed

    Murray, Benjamin J; Knopf, Daniel A; Bertram, Allan K

    2005-03-10

    An important mechanism for ice cloud formation in the Earth's atmosphere is homogeneous nucleation of ice in aqueous droplets, and this process is generally assumed to produce hexagonal ice. However, there are some reports that the metastable crystalline phase of ice, cubic ice, may form in the Earth's atmosphere. Here we present laboratory experiments demonstrating that cubic ice forms when micrometre-sized droplets of pure water and aqueous solutions freeze homogeneously at cooling rates approaching those found in the atmosphere. We find that the formation of cubic ice is dominant when droplets freeze at temperatures below 190 K, which is in the temperature range relevant for polar stratospheric clouds and clouds in the tropical tropopause region. These results, together with heat transfer calculations, suggest that cubic ice will form in the Earth's atmosphere. If there were a significant fraction of cubic ice in some cold clouds this could increase their water vapour pressure, and modify their microphysics and ice particle size distributions. Under specific conditions this may lead to enhanced dehydration of the tropopause region.

  1. 76 FR 1362 - Safety Zone; Ice Conditions for the Baltimore Captain of Port Zone

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-10

    ... Federal Register (73 FR 3316). Public Meeting We do not now plan to hold a public meeting. But you may... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Ice Conditions for the Baltimore Captain of.... This safety zone is necessary to protect mariners from the hazards associated with ice in the...

  2. Dynamic contact of droplet with superhydrophobic surface in conditions favour icing

    NASA Astrophysics Data System (ADS)

    Remer, M.; Sobieraj, G.; Gumowski, K.; Rokicki, J.; Psarski, M.; Marczak, J.; Celichowski, G.

    2014-08-01

    Flight like droplet impact with superhydrophobic substrate in conditions favour icing is discussed in this work. Test stand with fast camera and equipment eligible to obtain temperatures and humidity at different ranges, lead to results which can prove, that superhydrophobic surface might be good ice repellent substrate. The influence of air humidity on droplet freezing was confirmed.

  3. LANDSAT survey of near-shore ice conditions along the Arctic coast of Alaska

    NASA Technical Reports Server (NTRS)

    Stringer, W. J. (Principal Investigator); Barrett, S. A.

    1978-01-01

    The author has identified the following significant results. Winter and spring near-shore ice conditions were analyzed for the Beaufort Sea 1973-77, and the Chukchi Sea 1973-76. LANDSAT imagery was utilized to map major ice features related to regional ice morphology. Significant features from individual LANDSAT image maps were combined to yield regional maps of major ice ridge systems for each year of study and maps of flaw lead systems for representative seasons during each year. These regional maps were, in turn, used to prepare seasonal ice morphology maps. These maps showed, in terms of a zonal analysis, regions of statistically uniform ice behavior. The behavioral characteristics of each zone were described in terms of coastal processes and bathymetric configuration.

  4. Ice saturation at the tropopause observed from the ER-2 aircraft

    NASA Technical Reports Server (NTRS)

    Murphy, D. M.; Kelly, K. K.; Tuck, A. F.; Proffitt, M. H.; Kinne, S.

    1990-01-01

    Ice saturation at or just above the tropopause was frequently observed during the ER-2 vertical profiles over Stavanger (59 deg N) during the Airborne Arctic Stratospheric Expedition (AASE). On occasion, ice saturation extended as much as 500 m above the tropopause. Saturation was not observed over Punta Arenas (53 deg S) during the Airborne Antarctic Ozone Experiment. Saturation extending just above the tropopause was observed at Moffett Field (38 deg N) in winter but not in summer. The top of a thick cirrus layer at the tropopause will be very strongly cooled, and a thin cloud layer at the tropopause will either be strongly heated or cooled depending on the presence of lower level clouds. Some ER-2 data suggests removal of water and nitrogen species from the tropopause.

  5. Ice world: the origin of nucleobases in ice-liquid water coexistence conditions.

    NASA Astrophysics Data System (ADS)

    Menor Salvan, C.

    2013-09-01

    We could define the ice world as the chemical evolution in the range between freezing point of water and the limit of stability of liquid brines, ≈273 to 210 K. In this environment, the synthesis of nitrogen heterocycles using urea as nitrogen source and methane as precursor of active intermediates is favorable from a prebiotic chemistry standpoint, leading to a mixture dominated by pyrimidines and hydantoins. Hence, the synthesis in ice matrix constitutes an experimental model for the study of origin of nucleobases in Solar System bodies.

  6. 14 CFR 91.527 - Operating in icing conditions.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... airplane that has— (1) Frost, snow, or ice adhering to any propeller, windshield, or powerplant... each propeller, windshield, wing, stabilizing or control surface, and each airspeed, altimeter, rate of... to any propeller, windshield, stabilizing or control surface; to a powerplant installation; or to...

  7. Aircraft type influence on contrail properties

    NASA Astrophysics Data System (ADS)

    Jeßberger, P.; Voigt, C.; Schumann, U.; Sölch, I.; Schlager, H.; Kaufmann, S.; Petzold, A.; Schäuble, D.; Gayet, J.-F.

    2013-12-01

    The investigation of the impact of aircraft parameters on contrail properties helps to better understand the climate impact from aviation. Yet, in observations, it is a challenge to separate aircraft and meteorological influences on contrail formation. During the CONCERT campaign in November 2008, contrails from 3 Airbus passenger aircraft of types A319-111, A340-311 and A380-841 were probed at cruise under similar meteorological conditions with in situ instruments on board DLR research aircraft Falcon. Within the 2 min-old contrails detected near ice saturation, we find similar effective diameters Deff (5.2-5.9 μm), but differences in particle number densities nice (162-235 cm-3) and in vertical contrail extensions (120-290 m), resulting in large differences in contrail optical depths τ at 550 nm (0.25-0.94). Hence larger aircraft produce optically thicker contrails. Based on the observations, we apply the EULAG-LCM model with explicit ice microphysics and, in addition, the Contrail and Cirrus Prediction (CoCiP) model to calculate the aircraft type impact on young contrails under identical meteorological conditions. The observed increase in τ for heavier aircraft is confirmed by the models, yet for generally smaller τ. CoCiP model results suggest that the aircraft dependence of climate-relevant contrail properties persists during contrail lifetime, adding importance to aircraft-dependent model initialization. We finally derive an analytical relationship between contrail, aircraft and meteorological parameters. Near ice saturation, contrail width × τ scales linearly with the fuel flow rate, as confirmed by observations. For higher relative humidity with respect to ice (RHI), the analytical relationship suggests a non-linear increase in the form (RHI-12/3. Summarized, our combined results could help to more accurately assess the climate impact from aviation using an aircraft-dependent contrail parameterization.

  8. Sea-ice and North Atlantic climate response to CO2-induced warming and cooling conditions

    NASA Astrophysics Data System (ADS)

    Nazarenko, Larissa; Tausnev, Nickolai; Hansen, James

    Using a global climate model coupled with an ocean and a sea-ice model, we compare the effects of doubling CO2 and halving CO2 on sea-ice cover and connections with the atmosphere and ocean. An overall warming in the 2 × CO2 experiment causes reduction of sea-ice extent by 15%, with maximum decrease in summer and autumn, consistent with observed seasonal sea-ice changes. The intensification of the Northern Hemisphere circulation is reflected in the positive phase of the Arctic Oscillation (AO), associated with higher-than-normal surface pressure south of about 50° N and lower-than-normal surface pressure over the high northern latitudes. Strengthening the polar cell causes enhancement of westerlies around the Arctic perimeter during winter. Cooling, in the 0.5 × CO2 experiment, leads to thicker and more extensive sea ice. In the Southern Hemisphere, the increase in ice-covered area (28%) dominates the ice-thickness increase (5%) due to open ocean to the north. In the Northern Hemisphere, sea-ice cover increases by only 8% due to the enclosed land/sea configuration, but sea ice becomes much thicker (108%). Substantial weakening of the polar cell due to increase in sea-level pressure over polar latitudes leads to a negative trend of the winter AO index. The model reproduces large year-to-year variability under both cooling and warming conditions.

  9. Prediction of ice accretion on a swept NACA 0012 airfoil and comparisons to flight test results

    NASA Technical Reports Server (NTRS)

    Reehorst, Andrew L.

    1992-01-01

    In the winter of 1989-90, an icing research flight project was conducted to obtain swept wing ice accretion data. Utilizing the NASA Lewis Research Center's DHC-6 DeHavilland Twin Otter aircraft, research flights were made into known icing conditions in Northeastern Ohio. The icing cloud environment and aircraft flight data were measured and recorded by an onboard data acquisition system. Upon entry into the icing environment, a 24 inch span, 15 inch chord NACA 0012 airfoil was extended from the aircraft and set to the desired sweep angle. After the growth of a well defined ice shape, the airfoil was retracted into the aircraft cabin for ice shape documentation. The ice accretions were recorded by ice tracings and photographs. Ice accretions were mostly of the glaze type and exhibited scalloping. The ice was accreted at sweep angles of 0, 30, and 45 degrees. A 3-D ice accretion prediction code was used to predict ice profiles for five selected flight test runs, which include sweep angle of zero, 30, and 45 degrees. The code's roughness input parameter was adjusted for best agreement. A simple procedure was added to the code to account for 3-D ice scalloping effects. The predicted ice profiles are compared to their respective flight test counterparts. This is the first attempt to predict ice profiles on swept wings with significant scalloped ice formations.

  10. Ice Accretions and Icing Effects for Modern Airfoils

    NASA Technical Reports Server (NTRS)

    Addy, Harold E., Jr.

    2000-01-01

    Icing tests were conducted to document ice shapes formed on three different two-dimensional airfoils and to study the effects of the accreted ice on aerodynamic performance. The models tested were representative of airfoil designs in current use for each of the commercial transport, business jet, and general aviation categories of aircraft. The models were subjected to a range of icing conditions in an icing wind tunnel. The conditions were selected primarily from the Federal Aviation Administration's Federal Aviation Regulations 25 Appendix C atmospheric icing conditions. A few large droplet icing conditions were included. To verify the aerodynamic performance measurements, molds were made of selected ice shapes formed in the icing tunnel. Castings of the ice were made from the molds and placed on a model in a dry, low-turbulence wind tunnel where precision aerodynamic performance measurements were made. Documentation of all the ice shapes and the aerodynamic performance measurements made during the icing tunnel tests is included in this report. Results from the dry, low-turbulence wind tunnel tests are also presented.

  11. Identification of contrasting seasonal sea ice conditions during the Younger Dryas

    NASA Astrophysics Data System (ADS)

    Cabedo-Sanz, Patricia; Belt, Simon T.; Knies, Jochen; Husum, Katrine

    2013-11-01

    A palaeo sea ice reconstruction for northern Norway for the interval ca 13.8-7.2 cal ka BP has been performed using a combined organic geochemical proxy-based study of a marine sediment core (JM99-1200) obtained from Andfjorden (69° 15.95' N, 16° 25.09' E) and the outcomes compared with a series of other palaeoclimate studies carried out previously. Within this study, particular emphasis has been placed on the identification of the sea ice conditions during the Younger Dryas and the application of different biomarker-based proxies to both identify and quantify seasonal sea ice conditions. Firstly, the appearance of the specific sea ice diatom proxy IP25 at ca 12.9 cal ka BP in the sedimentary record has provided an unambiguous but qualitative measure of seasonal sea ice and thus the onset of the Younger Dryas stadial. The near continuous occurrence of IP25 for the next ca 1400 yr demonstrates seasonal sea ice during this interval, although variable abundances suggest that the recurrent conditions in the early-mid Younger Dryas (ca 12.9-11.9 cal ka BP) changed significantly from stable to highly variable sea ice conditions at ca 11.9 cal ka BP and this instability in sea ice prevailed for the subsequent ca 400 yr, during which, an extremely short interval of permanent or near-permanent sea ice was observed at ca 11.75 cal ka BP. At ca 11.5 cal ka BP, IP25 disappeared from the record indicating ice-free conditions that signified the beginning of the Holocene. The IP25 concentrations were also combined with those of the open water phytoplankton biomarker brassicasterol to generate PBIP25 data from which more quantitative measurements of sea ice were determined. PBIP25 data were consistent with, consecutively, seasonal then infrequent sea ice cover for the early-mid and late Younger Dryas, while further comparisons of the PBIP25 data with the outcomes of previous correlations with modelled sea ice concentrations suggested that these intervals were characterised by ca

  12. SIPEX 2012: Extreme sea-ice and atmospheric conditions off East Antarctica

    NASA Astrophysics Data System (ADS)

    Heil, P.; Stammerjohn, S.; Reid, P.; Massom, R. A.; Hutchings, J. K.

    2016-09-01

    In 2012, Antarctic sea-ice coverage was marked by weak annual-mean climate anomalies that consisted of opposing anomalies early and late in the year (some setting new records) which were interspersed by near-average conditions for most of the austral autumn and winter. Here, we investigate the ocean-ice-atmosphere system off East Antarctica, prior to and during the Sea Ice Physics and Ecosystems eXperiment [SIPEX] 2012, by exploring relationships between atmospheric and oceanic forcing together with the sea-ice and snow characteristics. During August and September 2012, just prior to SIPEX 2012, atmospheric circulation over the Southern Ocean was near-average, setting up the ocean-ice-atmosphere system for near-average conditions. However, below-average surface pressure and temperature as well as strengthened circumpolar winds prevailed during June and July 2012. This led to a new record (19.48×106 km2) in maximum Antarctic sea-ice extent recorded in late September. In contrast to the weak circum-Antarctic conditions, the East Antarctic sector (including the SIPEX 2012 region) experienced positive sea-ice extent and concentration anomalies during most of 2012, coincident with negative atmospheric pressure and sea-surface temperature anomalies. Heavily deformed sea ice appeared to be associated with intensified wind stress due to increased cyclonicity as well as an increased influx of sea ice from the east. This increased westward ice flux is likely linked to the break-up of nearly 80% of the Mertz Glacier Tongue in 2010, which strongly modified the coastal configuration and hence the width of the westward coastal current. Combined with favourable atmospheric conditions the associated changed coastal configuration allowed more sea ice to remain within the coastal current at the expense of a reduced northward flow in the region around 141°-145°E. In addition a westward propagating positive anomaly of sea-ice extent from the western Ross Sea during austral winter

  13. Effect of drop size on the impact thermodynamics for supercooled large droplet in aircraft icing

    NASA Astrophysics Data System (ADS)

    Zhang, Chen; Liu, Hong

    2016-06-01

    Supercooled large droplet (SLD), which can cause abnormal icing, is a well-known issue in aerospace engineering. Although efforts have been exerted to understand large droplet impact dynamics and the supercooled feature in the film/substrate interface, respectively, the thermodynamic effect during the SLD impact process has not received sufficient attention. This work conducts experimental studies to determine the effects of drop size on the thermodynamics for supercooled large droplet impingement. Through phenomenological reproduction, the rapid-freezing characteristics are observed in diameters of 400, 800, and 1300 μm. The experimental analysis provides information on the maximum spreading rate and the shrinkage rate of the drop, the supercooled diffusive rate, and the freezing time. A physical explanation of this unsteady heat transfer process is proposed theoretically, which indicates that the drop size is a critical factor influencing the supercooled heat exchange and effective heat transfer duration between the film/substrate interface. On the basis of the present experimental data and theoretical analysis, an impinging heating model is developed and applied to typical SLD cases. The model behaves as anticipated, which underlines the wide applicability to SLD icing problems in related fields.

  14. Examination of Icing Induced Loss of Control and Its Mitigations

    NASA Technical Reports Server (NTRS)

    Reehorst, Andrew L.; Addy, Harold E., Jr.; Colantonio, Renato O.

    2010-01-01

    Factors external to the aircraft are often a significant causal factor in loss of control (LOC) accidents. In today s aviation world, very few accidents stem from a single cause and typically have a number of causal factors that culminate in a LOC accident. Very often the "trigger" that initiates an accident sequence is an external environment factor. In a recent NASA statistical analysis of LOC accidents, aircraft icing was shown to be the most common external environmental LOC causal factor for scheduled operations. When investigating LOC accident or incidents aircraft icing causal factors can be categorized into groups of 1) in-flight encounter with super-cooled liquid water clouds, 2) take-off with ice contamination, or 3) in-flight encounter with high concentrations of ice crystals. As with other flight hazards, icing induced LOC accidents can be prevented through avoidance, detection, and recovery mitigations. For icing hazards, avoidance can take the form of avoiding flight into icing conditions or avoiding the hazard of icing by making the aircraft tolerant to icing conditions. Icing detection mitigations can take the form of detecting icing conditions or detecting early performance degradation caused by icing. Recovery from icing induced LOC requires flight crew or automated systems capable of accounting for reduced aircraft performance and degraded control authority during the recovery maneuvers. In this report we review the icing induced LOC accident mitigations defined in a recent LOC study and for each mitigation describe a research topic required to enable or strengthen the mitigation. Many of these research topics are already included in ongoing or planned NASA icing research activities or are being addressed by members of the icing research community. These research activities are described and the status of the ongoing or planned research to address the technology needs is discussed

  15. Mixed-Phase Icing Simulation and Testing at the Cox Icing Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Al-Khalil, Kamel; Irani, Eddie; Miller, Dean

    2003-01-01

    A new capability was developed for indoor simulation of snow and mixed-phase icing conditions. This capability is useful for year-round testing in the Cox closed-loop Icing Wind Tunnel. Certification of aircraft for flight into these types of icing conditions is only required by the JAA in Europe. In an effort to harmonize certification requirements, the FAA in the US sponsored a preliminary program to study the effects of mixed-phase and fully glaciated icing conditions on the performance requirements of thermal ice protection systems. This paper describes the test program and the associated results.

  16. Influence of Aerosol Chemical Composition on Heterogeneous Ice Formation under Mid-Upper Troposphere Conditions

    NASA Astrophysics Data System (ADS)

    Kanji, Z. A.; Niemand, M.; Saathoff, H.; Möhler, O.; Chou, C.; Abbatt, J.; Stetzer, O.

    2011-12-01

    Aerosols are involved in cooling/warming the atmosphere directly via interaction with incoming solar radiation (aerosol direct effect), or via their ability to act as cloud condensation or ice nuclei (IN) and thus play a role in cloud formation (indirect effect). In particular, the physical properties of aerosols such as size and solubility and chemical composition can influence their behavior and fate in the atmosphere. Ice nucleation taking place via IN is termed as heterogeneous ice nucleation and can take place with via deposition (ice forming on IN directly from the vapor phase), condensation/immersion (freezing via formation of the liquid phase on IN) or condensation (IN colliding with supercooled liquid drops). This presentation shows how the chemical composition and surface area of various tropospherically relevant aerosols influence conditions of temperature (T) and relative humidity (RH) required for heterogeneous ice formation conditions in the mid-upper troposphere regime (253 - 220K)? Motivation for this comes first from, the importance of being able to predict ice formation accurately so as to understand the hydrological cycle since the ice is the primary initiator of precipitation forming clouds. Second, the tropospheric budget of water vapour, an especially active greenhouse gas is strongly influenced by ice nucleation and growth. Third, ice surfaces in the atmosphere act as heterogeneous surfaces for chemical reactions of trace gases (e.g., SO2, O3, NOx and therefore being able to accurately estimate ice formation rates and quantify ice surface concentrations will allow a more accurate calculation of trace gas budgets in the troposphere. Ice nucleation measurements were conducted using a self-developed continuous flow diffusion chamber and static chamber. A number of tropospherically relevant particulates with naturally-varying and laboratory-modified surface chemistry/structure were investigated for their ice formation efficiency based on highest

  17. LANDSAT survey of near-shore ice conditions along the Arctic coast of Alaska

    NASA Technical Reports Server (NTRS)

    Stringer, W. J. (Principal Investigator)

    1975-01-01

    The author has identified the following significant results. On the basis of analysis of late winter 1973, 1974, and 1975 LANDSAT imagery of the Beaufort Sea coast of Alaska, the following conclusions regarding near-shore ice conditions were made: (1) by March, the seaward limit of contiguous ice is often beyond the 10 fathom contour. (2) During March, shearing can and does take place along a line roughly coincident with the 10 fathom contour. (3) Ice motions during these shearing events are not extremely great, generally on the order of 10 km. (4) Many large ice features have already been formed by late February. (5) Based on look-ahead at later LANDSAT imagery, it seems apparent that Beaufort Seas shore-fast ice was already formed by late February and may well be safe for exploratory activities from this data forward until the melt season.

  18. Dynamics of molecules in a supercooled water nanoparticle during the ice accretion on the aircraft surface

    NASA Astrophysics Data System (ADS)

    Amelyushkin, I. A.; Stasenko, A. L.

    2015-06-01

    The principal aim of this work is to elaborate a robust physical model and the corresponding numerical code for prediction of the icing startup due to numerous water nanoparticles in the supercooled humid air. For this purpose, a scientified approach was used which is based not on the quantum-mechanics considerations but on the information about intermolecular potentials (especially, Lennard-Jones (LJ), etc.) tightly connected with the state equations of the corresponding specie (e. g., van der Waals for air and water and Mie-Grünaisen for circumfluent body). u In other words, the principal idea of this work is to adequately ascribe certain macroscopic characteristics of a water nanoparticle which may significantly differ from those indicated in physical reference books for bulk materials.

  19. Ice nucleation by combustion ash particles at conditions relevant to mixed-phase clouds

    NASA Astrophysics Data System (ADS)

    Umo, N. S.; Murray, B. J.; Baeza-Romero, M. T.; Jones, J. M.; Lea-Langton, A. R.; Malkin, T. L.; O'Sullivan, D.; Plane, J. M. C.; Williams, A.

    2014-11-01

    Ice nucleating particles can modify cloud properties with implications for climate and the hydrological cycle; hence, it is important to understand which aerosol particle types nucleate ice and how efficiently they do so. It has been shown that aerosol particles such as natural dusts, volcanic ash, bacteria and pollen can act as ice nucleating particles, but the ice nucleating ability of combustion ashes has not been studied. Combustion ashes are major by-products released during the combustion of solid fuels and a significant amount of these ashes are emitted into the atmosphere either during combustion or via aerosolization of bottom ashes. Here, we show that combustion ashes (coal fly ash, wood bottom ash, domestic bottom ash, and coal bottom ash) nucleate ice in the immersion mode at conditions relevant to mixed-phase clouds. Hence, combustion ashes could play an important role in primary ice formation in mixed-phase clouds, especially in clouds that are formed near the emission source of these aerosol particles. In order to quantitatively assess the impact of combustion ashes on mixed-phase clouds, we propose that the atmospheric abundance of combustion ashes should be quantified since up to now they have mostly been classified together with mineral dust particles. Also, in reporting ice residue compositions, a distinction should be made between natural mineral dusts and combustion ashes in order to quantify the contribution of combustion ashes to atmospheric ice nucleation.

  20. Ice nucleation by combustion ash particles at conditions relevant to mixed-phase clouds

    NASA Astrophysics Data System (ADS)

    Umo, N. S.; Murray, B. J.; Baeza-Romero, M. T.; Jones, J. M.; Lea-Langton, A. R.; Malkin, T. L.; O'Sullivan, D.; Neve, L.; Plane, J. M. C.; Williams, A.

    2015-05-01

    Ice-nucleating particles can modify cloud properties with implications for climate and the hydrological cycle; hence, it is important to understand which aerosol particle types nucleate ice and how efficiently they do so. It has been shown that aerosol particles such as natural dusts, volcanic ash, bacteria and pollen can act as ice-nucleating particles, but the ice-nucleating ability of combustion ashes has not been studied. Combustion ashes are major by-products released during the combustion of solid fuels and a significant amount of these ashes are emitted into the atmosphere either during combustion or via aerosolization of bottom ashes. Here, we show that combustion ashes (coal fly ash, wood bottom ash, domestic bottom ash, and coal bottom ash) nucleate ice in the immersion mode at conditions relevant to mixed-phase clouds. Hence, combustion ashes could play an important role in primary ice formation in mixed-phase clouds, especially in clouds that are formed near the emission source of these aerosol particles. In order to quantitatively assess the impact of combustion ashes on mixed-phase clouds, we propose that the atmospheric abundance of combustion ashes should be quantified since up to now they have mostly been classified together with mineral dust particles. Also, in reporting ice residue compositions, a distinction should be made between natural mineral dusts and combustion ashes in order to quantify the contribution of combustion ashes to atmospheric ice nucleation.

  1. Reducing Conservatism in Aircraft Engine Response Using Conditionally Active Min-Max Limit Regulators

    NASA Technical Reports Server (NTRS)

    May, Ryan D.; Garg, Sanjay

    2012-01-01

    Current aircraft engine control logic uses a Min-Max control selection structure to prevent the engine from exceeding any safety or operational limits during transients due to throttle commands. This structure is inherently conservative and produces transient responses that are slower than necessary. In order to utilize the existing safety margins more effectively, a modification to this architecture is proposed, referred to as a Conditionally Active (CA) limit regulator. This concept uses the existing Min-Max architecture with the modification that limit regulators are active only when the operating point is close to a particular limit. This paper explores the use of CA limit regulators using a publicly available commercial aircraft engine simulation. The improvement in thrust response while maintaining all necessary safety limits is demonstrated in a number of cases.

  2. Active microwave measurements of sea ice under fall conditions: The RADARSAT/FIREX fall experiment. [in the Canadian Arctic

    NASA Technical Reports Server (NTRS)

    Onstott, R. G.; Kim, Y. S.; Moore, R. K.

    1984-01-01

    A series of measurements of the active microwave properties of sea ice under fall growing conditions was conducted. Ice in the inland waters of Mould Bay, Crozier Channel, and intrepid inlet and ice in the Arctic Ocean near Hardinge Bay was investigated. Active microwave data were acquired using a helicopter borne scatterometer. Results show that multiyear ice frozen in grey or first year ice is easily detected under cold fall conditions. Multiyear ice returns were dynamic due to response to two of its scene constituents. Floe boundaries between thick and thin ice are well defined. Multiyear pressure ridge returns are similar in level to background ice returns. Backscatter from homogeneous first year ice is seen to be primarily due to surface scattering. Operation at 9.6 GHz is more sensitive to the detailed changes in scene roughness, while operation at 5.6 GHz seems to track roughness changes less ably.

  3. Supercooling and Ice Formation of Perchlorate Brines under Mars-relevant Conditions

    NASA Astrophysics Data System (ADS)

    Primm, K.; Gough, R. V.; Tolbert, M. A.

    2015-12-01

    Perchlorate salts, discovered in the Martian regolith at multiple landing sites, may provide pathways for liquid water stability on current Mars. It has previously been assumed that if perchlorate brines form in the Martian regolith via melting or deliquescence, they would be present only briefly because efflorescence into a crystal or freezing to ice would soon occur. Here, we used a Raman microscope to study the temperature and relative humidity (RH) conditions at which magnesium perchlorate brine will form ice. Although ice is thermodynamically predicted to form whenever the saturation with respect to ice (Sice) is greater than or equal to 1, ice formation by perchlorate brines did not occur until elevated Sice values were reached: Sice= 1.17, 1.29, and 1.25 at temperatures of 218 K, 230.5 K, and 244 K, respectively. If a magnesium perchlorate particle was allowed to deliquesce completely prior to experiencing ice supersaturation, the extent of supercooling was increased even further. These high supersaturation values imply perchlorate brines can exist over a wider range of conditions than previously believed. From these experiments it has been found that magnesium perchlorate exhibits supercooling well into the previous theoretical ice region of the stability diagram and that liquid brines on Mars could potentially exist for up to two additional hours per sol. This supercooling of magnesium perchlorate will help with the exploration of Mars by the Mars 2020 spacecraft by helping to understand the phase and duration of water existing in the Martian subsurface.

  4. Subglacial conditions at a sticky spot along Kamb Ice Stream, West Antarctica

    USGS Publications Warehouse

    Peters, L.E.; Anandakrishnan, S.

    2007-01-01

    We present the results of a seismic reflection experiment performed transverse to flow a few tens of kilometers above the main trunk of Kamb Ice Stream, West Antarctica, where we image a basal high surrounded by variable subglacial conditions. This high rises as much as 200 m above the surrounding bed, acting as a major sticking point that resists fast flow. Application of the amplitude variation with offset (AVO) seismic technique has highlighted regions of frozen sediments along our profile, suggesting that the ice stream is experiencing basal freeze-on in the region. The bedrock high appears to be at least partially draped in sediment cover, with a concentrated area of weak, dilatant till flanking one edge. This dilatant till is further dispersed along our profile, though it does not possess enough continuity to maintain streaming ice conditions. These results support the hypothesis that the ongoing shutdown of Kamb Ice Stream is due to a loss in continuous basal lubrication.

  5. Pre-Partum Diet of Adult Female Bearded Seals in Years of Contrasting Ice Conditions

    PubMed Central

    Hindell, Mark A.; Lydersen, Christian; Hop, Haakon; Kovacs, Kit M.

    2012-01-01

    Changing patterns of sea-ice distribution and extent have measurable effects on polar marine systems. Beyond the obvious impacts of key-habitat loss, it is unclear how such changes will influence ice-associated marine mammals in part because of the logistical difficulties of studying foraging behaviour or other aspects of the ecology of large, mobile animals at sea during the polar winter. This study investigated the diet of pregnant bearded seals (Erignathus barbatus) during three spring breeding periods (2005, 2006 and 2007) with markedly contrasting ice conditions in Svalbard using stable isotopes (δ13C and δ15N) measured in whiskers collected from their newborn pups. The δ15N values in the whiskers of individual seals ranged from 11.95 to 17.45 ‰, spanning almost 2 full trophic levels. Some seals were clearly dietary specialists, despite the species being characterised overall as a generalist predator. This may buffer bearded seal populations from the changes in prey distributions lower in the marine food web which seems to accompany continued changes in temperature and ice cover. Comparisons with isotopic signatures of known prey, suggested that benthic gastropods and decapods were the most common prey. Bayesian isotopic mixing models indicated that diet varied considerably among years. In the year with most fast-ice (2005), the seals had the greatest proportion of pelagic fish and lowest benthic invertebrate content, and during the year with the least ice (2006), the seals ate more benthic invertebrates and less pelagic fish. This suggests that the seals fed further offshore in years with greater ice cover, but moved in to the fjords when ice-cover was minimal, giving them access to different types of prey. Long-term trends of sea ice decline, earlier ice melt, and increased water temperatures in the Arctic are likely to have ecosystem-wide effects, including impacts on the forage bases of pagophilic seals. PMID:22693616

  6. Pre-partum diet of adult female bearded seals in years of contrasting ice conditions.

    PubMed

    Hindell, Mark A; Lydersen, Christian; Hop, Haakon; Kovacs, Kit M

    2012-01-01

    Changing patterns of sea-ice distribution and extent have measurable effects on polar marine systems. Beyond the obvious impacts of key-habitat loss, it is unclear how such changes will influence ice-associated marine mammals in part because of the logistical difficulties of studying foraging behaviour or other aspects of the ecology of large, mobile animals at sea during the polar winter. This study investigated the diet of pregnant bearded seals (Erignathus barbatus) during three spring breeding periods (2005, 2006 and 2007) with markedly contrasting ice conditions in Svalbard using stable isotopes (δ(13)C and δ(15)N) measured in whiskers collected from their newborn pups. The δ(15)N values in the whiskers of individual seals ranged from 11.95 to 17.45 ‰, spanning almost 2 full trophic levels. Some seals were clearly dietary specialists, despite the species being characterised overall as a generalist predator. This may buffer bearded seal populations from the changes in prey distributions lower in the marine food web which seems to accompany continued changes in temperature and ice cover. Comparisons with isotopic signatures of known prey, suggested that benthic gastropods and decapods were the most common prey. Bayesian isotopic mixing models indicated that diet varied considerably among years. In the year with most fast-ice (2005), the seals had the greatest proportion of pelagic fish and lowest benthic invertebrate content, and during the year with the least ice (2006), the seals ate more benthic invertebrates and less pelagic fish. This suggests that the seals fed further offshore in years with greater ice cover, but moved in to the fjords when ice-cover was minimal, giving them access to different types of prey. Long-term trends of sea ice decline, earlier ice melt, and increased water temperatures in the Arctic are likely to have ecosystem-wide effects, including impacts on the forage bases of pagophilic seals. PMID:22693616

  7. Pre-partum diet of adult female bearded seals in years of contrasting ice conditions.

    PubMed

    Hindell, Mark A; Lydersen, Christian; Hop, Haakon; Kovacs, Kit M

    2012-01-01

    Changing patterns of sea-ice distribution and extent have measurable effects on polar marine systems. Beyond the obvious impacts of key-habitat loss, it is unclear how such changes will influence ice-associated marine mammals in part because of the logistical difficulties of studying foraging behaviour or other aspects of the ecology of large, mobile animals at sea during the polar winter. This study investigated the diet of pregnant bearded seals (Erignathus barbatus) during three spring breeding periods (2005, 2006 and 2007) with markedly contrasting ice conditions in Svalbard using stable isotopes (δ(13)C and δ(15)N) measured in whiskers collected from their newborn pups. The δ(15)N values in the whiskers of individual seals ranged from 11.95 to 17.45 ‰, spanning almost 2 full trophic levels. Some seals were clearly dietary specialists, despite the species being characterised overall as a generalist predator. This may buffer bearded seal populations from the changes in prey distributions lower in the marine food web which seems to accompany continued changes in temperature and ice cover. Comparisons with isotopic signatures of known prey, suggested that benthic gastropods and decapods were the most common prey. Bayesian isotopic mixing models indicated that diet varied considerably among years. In the year with most fast-ice (2005), the seals had the greatest proportion of pelagic fish and lowest benthic invertebrate content, and during the year with the least ice (2006), the seals ate more benthic invertebrates and less pelagic fish. This suggests that the seals fed further offshore in years with greater ice cover, but moved in to the fjords when ice-cover was minimal, giving them access to different types of prey. Long-term trends of sea ice decline, earlier ice melt, and increased water temperatures in the Arctic are likely to have ecosystem-wide effects, including impacts on the forage bases of pagophilic seals.

  8. A Flight Evaluation and Analysis of the Effect of Icing Conditions on the ZPG-2 Airship

    NASA Technical Reports Server (NTRS)

    Lewis, Willilam; Perkins, Porter J., Jr.

    1958-01-01

    A series of test flights was conducted by the U. S. Navy over a 3- year period to evaluate the effects of icing on the operation of the ZPG-2 airship. In supercooled. clouds, ice formed only on the forward edges of small protuberances and wires and presented no serious hazard to operation. Ice accretions of the glaze type which occurred in conditions described as freezing drizzle adversely affected various components to a somewhat greater extent. The results indicated, a need for protection of certain components such as antennas, propellers, and certain parts of the control system. The tests showed that icing of the large surface of the envelope occurred only in freezing rain or drizzle. Because of the infrequent occurrence of these conditions, the potential maximum severity could not be estimated from the test results. The increases in heaviness caused by icing in freezing rain and drizzle were substantial, but well within the operational capabilities of the airship. In order to estimate the potential operational significance of icing in freezing rain, theoretical calculations were used to estimate: (1) the rate of icing as a function of temperature and rainfall intensity, (2) the climatological probability of occurrence of various combinations of these variables, and (3) the significance of the warming influence of the ocean in alleviating freezing-rain conditions. The results of these calculations suggest that, although very heavy icing rates are possible in combinations of low temperature and high rainfall rate, the occurrence of such conditions is very infrequent in coastal areas and virtually impossible 200 or 300 miles offshore.

  9. Simulation of flow and habitat conditions under ice, Cache la Poudre River - January 2006

    USGS Publications Warehouse

    Waddle, Terry

    2007-01-01

    The objectives of this study are (1) to describe the extent and thickness of ice cover, (2) simulate depth and velocity under ice at the study site for observed and reduced flows, and (3) to quantify fish habitat in this portion of the mainstem Cache la Poudre River for the current winter release schedule as well as for similar conditions without the 0.283 m3/s winter release.

  10. Practical Application of a Subscale Transport Aircraft for Flight Research in Control Upset and Failure Conditions

    NASA Technical Reports Server (NTRS)

    Cunningham, Kevin; Foster, John V.; Morelli, Eugene A.; Murch, Austin M.

    2008-01-01

    Over the past decade, the goal of reducing the fatal accident rate of large transport aircraft has resulted in research aimed at the problem of aircraft loss-of-control. Starting in 1999, the NASA Aviation Safety Program initiated research that included vehicle dynamics modeling, system health monitoring, and reconfigurable control systems focused on flight regimes beyond the normal flight envelope. In recent years, there has been an increased emphasis on adaptive control technologies for recovery from control upsets or failures including damage scenarios. As part of these efforts, NASA has developed the Airborne Subscale Transport Aircraft Research (AirSTAR) flight facility to allow flight research and validation, and system testing for flight regimes that are considered too risky for full-scale manned transport airplane testing. The AirSTAR facility utilizes dynamically-scaled vehicles that enable the application of subscale flight test results to full scale vehicles. This paper describes the modeling and simulation approach used for AirSTAR vehicles that supports the goals of efficient, low-cost and safe flight research in abnormal flight conditions. Modeling of aerodynamics, controls, and propulsion will be discussed as well as the application of simulation to flight control system development, test planning, risk mitigation, and flight research.

  11. Neural Partial Differentiation for Aircraft Parameter Estimation Under Turbulent Atmospheric Conditions

    NASA Astrophysics Data System (ADS)

    Kuttieri, R. A.; Sinha, M.

    2012-07-01

    An approach based on neural partial differentiation is suggested for aircraft parameter estimation using the flight data gathered under turbulent atmospheric conditions. The classical methods such as output error and equation error methods suffer from severe convergence issues; resulting in biased, inaccurate, and inconsistent estimates. Though filter error method yields better estimates while dealing with the flight data having process noise, it has few demerits like computational overheads and it allows estimation of a single set of process noise distribution matrix. The proposed neural method does not face any such problem of the classical methods. Moreover, the neural method does not require parameter initialization and a priori knowledge of the model structure. The neural network maps the aircraft state and control variables into the output variables corresponding to aerodynamic forces and moments. The parameter estimation, pertaining to lateral-directional motion, of the research aircraft de Havilland DHC-2 with simulated process noise, is presented. The results obtained using the neural partial differentiation are compared with the nominal values given in literature and with the classical methods. The neural method yields the aerodynamic derivatives very close to the nominal values and having quite low standard deviation. The neural methodology is also validated by comparing actual output variables with the neural predicted and neural reconstructed variables.

  12. Aircraft type influence on contrail properties

    NASA Astrophysics Data System (ADS)

    Jeßberger, P.; Voigt, C.; Schumann, U.; Sölch, I.; Schlager, H.; Kaufmann, S.; Petzold, A.; Schäuble, D.; Gayet, J.-F.

    2013-05-01

    The investigation of the impact of aircraft parameters on contrail properties helps to better understand the climate impact from aviation. Yet, in observations, it is a challenge to separate aircraft and meteorological influences on contrail formation. During the CONCERT campaign in November 2008, contrails from 3 Airbus passenger aircraft of type A319-111, A340-311 and A380-841 were probed at cruise under similar meteorological conditions with in-situ instruments on board the DLR research aircraft Falcon. Within the 2 min old contrails detected near ice saturation, we find similar effective diameters Deff (5.2-5.9 μm), but differences in particle number densities nice (162-235 cm-3) and in vertical contrail extensions (120-290 m), resulting in large differences in contrail optical depths τ (0.25-0.94). Hence larger aircraft produce optically thicker contrails. Based on the observations, we apply the EULAG-LCM model with explicit ice microphysics and in addition the Contrail and Cirrus Prediction model CoCiP to calculate the aircraft type impact on young contrails under identical meteorological conditions. The observed increase in τ for heavier aircraft is confirmed by the models, yet for generally smaller τ. An aircraft dependence of climate relevant contrail properties persists during contrail lifetime, adding importance to aircraft dependent model initialization. We finally derive an analytical relationship between contrail, aircraft and meteorological parameters. Near ice saturation, contrail width × τ scales linearly with fuel flow rate as confirmed by observations. For higher saturation ratios approximations from theory suggest a non-linear increase in the form (RHI-1)2/3. Summarized our combined results could help to more accurately assess the climate impact from aviation using an aircraft dependent contrail parameterization.

  13. Cyclone-induced rapid creation of extreme Antarctic sea ice conditions

    PubMed Central

    Wang, Zhaomin; Turner, John; Sun, Bo; Li, Bingrui; Liu, Chengyan

    2014-01-01

    Two polar vessels, Akademik Shokalskiy and Xuelong, were trapped by thick sea ice in the Antarctic coastal region just to the west of 144°E and between 66.5°S and 67°S in late December 2013. This event demonstrated the rapid establishment of extreme Antarctic sea ice conditions on synoptic time scales. The event was associated with cyclones that developed at lower latitudes. Near the event site, cyclone-enhanced strong southeasterly katabatic winds drove large westward drifts of ice floes. In addition, the cyclones also gave southward ice drift. The arrival and grounding of Iceberg B9B in Commonwealth Bay in March 2011 led to the growth of fast ice around it, forming a northward protruding barrier. This barrier blocked the westward ice drift and hence aided sea ice consolidation on its eastern side. Similar cyclone-induced events have occurred at this site in the past after the grounding of Iceberg B9B. Future events may be predictable on synoptic time scales, if cyclone-induced strong wind events can be predicted. PMID:24937550

  14. Cyclone-induced rapid creation of extreme Antarctic sea ice conditions.

    PubMed

    Wang, Zhaomin; Turner, John; Sun, Bo; Li, Bingrui; Liu, Chengyan

    2014-01-01

    Two polar vessels, Akademik Shokalskiy and Xuelong, were trapped by thick sea ice in the Antarctic coastal region just to the west of 144°E and between 66.5°S and 67°S in late December 2013. This event demonstrated the rapid establishment of extreme Antarctic sea ice conditions on synoptic time scales. The event was associated with cyclones that developed at lower latitudes. Near the event site, cyclone-enhanced strong southeasterly katabatic winds drove large westward drifts of ice floes. In addition, the cyclones also gave southward ice drift. The arrival and grounding of Iceberg B9B in Commonwealth Bay in March 2011 led to the growth of fast ice around it, forming a northward protruding barrier. This barrier blocked the westward ice drift and hence aided sea ice consolidation on its eastern side. Similar cyclone-induced events have occurred at this site in the past after the grounding of Iceberg B9B. Future events may be predictable on synoptic time scales, if cyclone-induced strong wind events can be predicted.

  15. Technical Note: Formation of airborne ice crystals in a wall independent reactor (WIR) under atmospheric conditions

    NASA Astrophysics Data System (ADS)

    Fries, E.; Haunold, W.; Starokozhev, E.; Palitzsch, K.; Sitals, R.; Jaeschke, W.; Püttmann, W.

    2008-07-01

    Both, gas and particle scavenging contribute to the transport of organic compounds by ice crystals in the troposphere. To simulate these processes an experimental setup was developed to form airborne ice crystals under atmospheric conditions. Experiments were performed in a wall independent reactor (WIR) installed in a walk-in cold chamber maintained constantly at -20°C. Aerosol particles were added to the carrier gas of ambient air by an aerosol generator to allow heterogeneous ice formation. Temperature variations and hydrodynamic conditions of the WIR were investigated to determine the conditions for ice crystal formation and crystal growth by vapour deposition. In detail, the dependence of temperature variations from flow rate and temperature of the physical wall as well as temperature variations with an increasing reactor depth were studied. The conditions to provide a stable aerosol concentration in the carrier gas flow were also studied. The temperature distribution inside the reactor was strongly dependent on flow rate and physical wall temperature. At an inlet temperature of -20°C, a flow rate of 30 L•min-1 and a physical wall temperature of +5°C turned out to provide ideal conditions for ice formation. At these conditions a sharp and stable laminar down draft "jet stream" of cold air in the centre of the reactor was produced. Temperatures measured at the chamber outlet were kept well below the freezing point in the whole reactor depth of 1.0 m. Thus, melting did not affect ice formation and crystal growth. The maximum residence time for airborne ice crystals was calculated to at 40 s. Ice crystal growth rates increased also with increasing reactor depth. The maximum ice crystal growth rate was calculated at 2.82 mg• s-1. Further, the removal efficiency of the cleaning device for aerosol particles was 99.8% after 10 min. A reliable particle supply was attained after a preliminary lead time of 15 min. Thus, the minimum lead time was determined at 25

  16. Experimental investigation on performance of ice storage air-conditioning system with separate heat pipe

    SciTech Connect

    Fang, Guiyin; Liu, Xu; Wu, Shuangmao

    2009-11-15

    An experimental study on operation performance of ice storage air-conditioning system with separate helical heat pipe is conducted in this paper. The experimental system of ice storage air-conditioning system with separate heat pipe is set up. The performance parameters such as the evaporation pressure and the condensation pressure of refrigeration system, the refrigeration capacity and the COP (coefficient of performance) of the system, the IPF (ice packing factor) and the cool storage capacity in the cool storage tank during charging period, and the cool discharge rate and the cool discharge capacity in the cool storage tank, the outlet water temperature in the cool storage tank and the outlet air temperature in room unit during discharging period are investigated. The experimental results show that the ice storage air-conditioning system with separate helical heat pipe can stably work during charging and discharging period. This indicates that the ice storage air-conditioning system with separate helical heat pipe is well adapted to cool storage air-conditioning systems in building. (author)

  17. High Arctic sea ice conditions influence marine birds wintering in Low Arctic regions

    NASA Astrophysics Data System (ADS)

    McFarlane Tranquilla, Laura; Hedd, April; Burke, Chantelle; Montevecchi, William A.; Regular, Paul M.; Robertson, Gregory J.; Stapleton, Leslie Ann; Wilhelm, Sabina I.; Fifield, David A.; Buren, Alejandro D.

    2010-09-01

    Ocean climate change is having profound biological effects in polar regions. Such change can also have far-reaching downstream effects in sub-polar regions. This study documents an environmental relationship between High Arctic sea ice changes and mortality events of marine birds in Low Arctic coastal regions. During April 2007 and March 2009, hundreds of beached seabird carcasses and moribund seabirds were found along the east and northeast coasts of Newfoundland, Canada. These seabird "wrecks" (i.e. dead birds on beaches) coincided with a period of strong, persistent onshore winds and heavily-accumulated sea ice that blocked bays and trapped seabirds near beaches. Ninety-two percent of wreck seabirds were Thick-billed Murres ( Uria lomvia). Body condition and demographic patterns of wreck murres were compared to Thick-billed Murres shot in the Newfoundland murre hunt. Average body and pectoral masses of wreck carcasses were 34% and 40% lighter (respectively) than shot murres, indicating that wreck birds had starved. The acute nature of each wreck suggested that starvation and associated hypothermia occurred within 2-3 days. In 2007, first-winter murres (77%) dominated the wreck. In 2009, there were more adults (78%), mostly females (66%). These results suggest that spatial and temporal segregation in ages and sexes can play a role in differential survival when stochastic weather conditions affect discrete areas where these groups aggregate. In wreck years, southward movement of Arctic sea ice to Low Arctic latitudes was later and blocked bays longer than in most other years. These inshore conditions corresponded with recent climate-driven changes in High Arctic ice break-up and ice extent; coupled with local weather conditions, these ice conditions appeared to be the key environmental features that precipitated the ice-associated seabird wrecks in the Low Arctic region.

  18. Descent strategy comparisons for TNAV-equipped aircraft under airplane-preferred operating conditions

    NASA Technical Reports Server (NTRS)

    Izumi, K. H.

    1989-01-01

    Three 4-D descent strategies were evaluated which were employed by TNAV-equipped aircraft in an advanced metering air traffic control environment. The Flow Management Evaluation Model (FMEM) was used to assess performance using three criteria when traffic enters the simulation under preferred cruise operating conditions (altitude and speed): throughput, fuel usage, and conflict probability. In comparison to an evaluation previously performed under NASA contract, the current analysis indicates that the optimal descent strategy is preferred over the clean-idle and constant descent angle (CFPA) strategies when all three criteria are considered.

  19. Experiments on the resistance of a large transport vessel navigating in the Arctic region in pack ice conditions

    NASA Astrophysics Data System (ADS)

    Huang, Yan; Li, Wei; Wang, Yinghui; Wu, Baoshan

    2016-07-01

    In this study, we carried out model tests to investigate the ice failure process and the resistance experienced by a transport vessel navigating in the Arctic region in pack ice conditions. We tested different navigation velocities, ice plate sizes, and ice concentrations. During the tests, we closely observed several phenomena, including the modes of interaction of the ice ship and the moving and failure modes of ice. We also measured the vessel resistances under different conditions. The test results indicate that the navigation velocity is a significant determinant of the moving and failure modes of ice. Moreover, vessel resistance is remarkably dependent on the ice concentration and navigation velocity. The variances of the mean and maximum resistance are also compared and discussed in detail.

  20. Experiments on the resistance of a large transport vessel navigating in the Arctic region in pack ice conditions

    NASA Astrophysics Data System (ADS)

    Huang, Yan; Li, Wei; Wang, Yinghui; Wu, Baoshan

    2016-09-01

    In this study, we carried out model tests to investigate the ice failure process and the resistance experienced by a transport vessel navigating in the Arctic region in pack ice conditions. We tested different navigation velocities, ice plate sizes, and ice concentrations. During the tests, we closely observed several phenomena, including the modes of interaction of the ice ship and the moving and failure modes of ice. We also measured the vessel resistances under different conditions. The test results indicate that the navigation velocity is a significant determinant of the moving and failure modes of ice. Moreover, vessel resistance is remarkably dependent on the ice concentration and navigation velocity. The variances of the mean and maximum resistance are also compared and discussed in detail.

  1. Long range transmission loss of broadband seismic pulses in the Arctic under ice-free conditions.

    PubMed

    Thode, Aaron; Kim, Katherine H; Greene, Charles R; Roth, Ethan

    2010-10-01

    In 2008 the Louis S. St-Laurent (LSSL) surveyed deep Arctic waters using a three-airgun seismic source. Signals from the seismic survey were detected between 400 km and 1300 km range on a directional autonomous acoustic recorder deployed in water 53 m deep off the Alaskan North Slope. Observations of received signal levels between 10-450 Hz versus LSSL range roughly fit a cylindrical transmission loss model plus 0.01 dB/km attenuation in deep ice-free waters, and fit previous empirical models in ice-covered waters. The transition between ice-free and ice-covered propagation conditions shifted 200 km closer to the recorder during the survey. PMID:20968323

  2. Comparison of adjoint and nudging methods to initialise ice sheet model basal conditions

    NASA Astrophysics Data System (ADS)

    Mosbeux, Cyrille; Gillet-Chaulet, Fabien; Gagliardini, Olivier

    2016-07-01

    Ice flow models are now routinely used to forecast the ice sheets' contribution to 21st century sea-level rise. For such short term simulations, the model response is greatly affected by the initial conditions. Data assimilation algorithms have been developed to invert for the friction of the ice on its bedrock using observed surface velocities. A drawback of these methods is that remaining uncertainties, especially in the bedrock elevation, lead to non-physical ice flux divergence anomalies resulting in undesirable transient effects. In this study, we compare two different assimilation algorithms based on adjoints and nudging to constrain both bedrock friction and elevation. Using synthetic twin experiments with realistic observation errors, we show that the two algorithms lead to similar performances in reconstructing both variables and allow the flux divergence anomalies to be significantly reduced.

  3. Measurement of the Critical Distance Parameter Against Icing Conditions on a NACA 0012 Swept Wing Tip

    NASA Technical Reports Server (NTRS)

    Vargas, Mario; Kreeger, Richard E.

    2011-01-01

    This work presents the results of three experiments, one conducted in the Icing Research Tunnel (IRT) at NASA Glenn Research Center and two in the Goodrich Icing Wind Tunnel (IWT). The experiments were designed to measure the critical distance parameter on a NACA 0012 Swept Wing Tip at sweep angles of 45deg, 30deg, and 15deg. A time sequence imaging technique (TSIT) was used to obtain real time close-up imaging data during the first 2 min of the ice accretion formation. The time sequence photographic data was used to measure the critical distance at each icing condition and to study how it develops in real time. The effect on the critical distance of liquid water content, drop size, total temperature, and velocity was studied. The results were interpreted using a simple energy balance on a roughness element

  4. Sea Ice Mapping using Unmanned Aerial Systems

    NASA Astrophysics Data System (ADS)

    Solbø, S.; Storvold, R.

    2011-12-01

    Mapping of sea ice extent and sea ice features is an important task in climate research. Since the arctic coastal and oceanic areas have a high probability of cloud coverage, aerial platforms are superior to satellite measurements for high-resolution optical measurements. However, routine observations of sea ice conditions present a variety of problems using conventional piloted aircrafts. Specially, the availability of suitable aircrafts for lease does not cover the demand in major parts of the arctic. With the recent advances in unmanned aerial systems (UAS), there is a high possibility of establishing routine, cost effective aerial observations of sea ice conditions in the near future. Unmanned aerial systems can carry a wide variety of sensors useful for characterizing sea-ice features. For instance, the CryoWing UAS, a system initially designed for measurements of the cryosphere, can be equipped with digital cameras, surface thermometers and laser altimeters for measuring freeboard of ice flows. In this work we will present results from recent CryoWing sea ice flights on Svalbard, Norway. The emphasis will be on data processing for stitching together images acquired with the non-stabilized camera payload, to form high-resolution mosaics covering large spatial areas. These data are being employed to map ice conditions; including ice and lead features and melt ponds. These high-resolution mosaics are also well suited for sea-ice mechanics, classification studies and for validation of satellite sea-ice products.

  5. CFD Variability for a Civil Transport Aircraft Near Buffet-Onset Conditions

    NASA Technical Reports Server (NTRS)

    Rumsey, Christopher L.; Morrison, Joseph H.; Biedron, Robert T.

    2003-01-01

    A CFD sensitivity analysis is conducted for an aircraft at several conditions, including flow with substantial separation (buffet onset). The sensitivity is studied using two different Navier-Stokes computer codes, three different turbulence models, and two different grid treatments of the wing trailing edge. This effort is a follow-on to an earlier study of CFD variation over a different aircraft in buffet onset conditions. Similar to the earlier study, the turbulence model is found to have the largest effect, with a variation of 3.8% in lift at the buffet onset angle of attack. Drag and moment variation are 2.9% and 23.6%, respectively. The variations due to code and trailing edge cap grid are smaller than that due to turbulence model. Overall, the combined approximate error band in CFD due to code, turbulence model, and trailing edge treatment at the buffet onset angle of attack are: 4% in lift, 3% in drag, and 31% in moment. The CFD results show similar trends to flight test data, but also exhibit a lift curve break not seen in the data.

  6. The effect of ice ingestion on female athletes performing intermittent exercise in hot conditions.

    PubMed

    Zimmermann, Matthew Robert; Landers, Grant Justin

    2015-01-01

    Studies have reported the benefits of pre-cooling prior to exercise in the heat for male athletes, but at this time no research has investigated female athletes. The aim of the following study was to test the effects of pre-cooling on female repeat sprint performance in hot, humid conditions; namely is ice ingestion effective in reducing core temperature (Tc) and does this reduced Tc lead to improved repeat sprint performance in female athletes? Nine female team sport athletes with mean age (21.0 ± 1.2 y), height (169.8 ± 4.1 cm) and body mass (62.3 ± 5.0 kg) participated in this study. Participants completed 72 min of an intermittent sprint protocol (ISP) consisting of 2 × 36 min halves in hot, humid conditions (33.1 ± 0.1 °C, 60.3 ± 1.5% RH) on a cycle ergometer. This was preceded by 30 min of either ice ingestion (ICE) or water consumption (CON) in a randomised order. At the end of the pre-cooling period, Tc significantly decreased following ICE (-0.7 ± 0.3 °C) compared to CON (-0.1 ± 0.2 °C; p = 0.001). Tc also remained lower in ICE compared to CON during the ISP (p = 0.001). Ratings of perceived thermal sensation were lower in ICE compared to CON (p = 0.032) at the beginning (p = 0.022) and mid-point (p = 0.035) of the second half. No differences in work, mean power, peak power, rating of perceived exertion, heart rate or sweat loss between conditions were recorded (p > 0.05). Ice ingestion significantly reduced female Tc prior to intermittent exercise in the heat and reduced thermal sensation; however, this did not coincide with improved performance.

  7. Ice crystal ingestion by turbofans

    NASA Astrophysics Data System (ADS)

    Rios Pabon, Manuel A.

    proposed and built in this Thesis, called DBDAIS, with a complete description of the anti-ice cycle. Contrary to existing ice protection systems, which either heat the aircraft surfaces, or mechanically remove the accreted ice, the DBDAIS employs non-thermal plasma discharges to prevent ice accretion. A new apparatus that mimics inflight icing based on combining the liquid sprays of liquid nitrogen and water was designed and fabricated, named LNITA. The apparatus produces ice similar to glaze ice and rime ice, the two characteristic types of ice from inflight icing, at the cost of 1% of similar tests in icing wind tunnels. Nineteen experiments of the DBDAIS were performed in the LNITA. The results from the experiments point to 32 kV and 4 kHz being adequate to prevent ice accretion, with a power consumption of 1 W/cm2. This compares favorably to existing ice protection systems, which typically run at 10 W/cm2, and to the power consumption of a typical electric stove burner at maximum power, which is 5 W/cm2. To complete this Thesis, a design and development project is proposed to implement the DBDAIS in Unmanned Aircraft Systems (UAS), with the selection of standard FAA inflight icing conditions, the run of 240 LEWICE simulations, and an analysis of the run results. The computational results lead to the design of a wing boot covering the airfoil from 20% of the lower pressure surface to 4% of the upper suction surface as the optimal protection for a UAS.

  8. Increased Land Use by Chukchi Sea Polar Bears in Relation to Changing Sea Ice Conditions.

    PubMed

    Rode, Karyn D; Wilson, Ryan R; Regehr, Eric V; St Martin, Michelle; Douglas, David C; Olson, Jay

    2015-01-01

    Recent observations suggest that polar bears (Ursus maritimus) are increasingly using land habitats in some parts of their range, where they have minimal access to their preferred prey, likely in response to loss of their sea ice habitat associated with climatic warming. We used location data from female polar bears fit with satellite radio collars to compare land use patterns in the Chukchi Sea between two periods (1986-1995 and 2008-2013) when substantial summer sea-ice loss occurred. In both time periods, polar bears predominantly occupied sea-ice, although land was used during the summer sea-ice retreat and during the winter for maternal denning. However, the proportion of bears on land for > 7 days between August and October increased between the two periods from 20.0% to 38.9%, and the average duration on land increased by 30 days. The majority of bears that used land in the summer and for denning came to Wrangel and Herald Islands (Russia), highlighting the importance of these northernmost land habitats to Chukchi Sea polar bears. Where bears summered and denned, and how long they spent there, was related to the timing and duration of sea ice retreat. Our results are consistent with other studies supporting increased land use as a common response of polar bears to sea-ice loss. Implications of increased land use for Chukchi Sea polar bears are unclear, because a recent study observed no change in body condition or reproductive indices between the two periods considered here. This result suggests that the ecology of this region may provide a degree of resilience to sea ice loss. However, projections of continued sea ice loss suggest that polar bears in the Chukchi Sea and other parts of the Arctic may increasingly use land habitats in the future, which has the potential to increase nutritional stress and human-polar bear interactions.

  9. Increased Land Use by Chukchi Sea Polar Bears in Relation to Changing Sea Ice Conditions.

    PubMed

    Rode, Karyn D; Wilson, Ryan R; Regehr, Eric V; St Martin, Michelle; Douglas, David C; Olson, Jay

    2015-01-01

    Recent observations suggest that polar bears (Ursus maritimus) are increasingly using land habitats in some parts of their range, where they have minimal access to their preferred prey, likely in response to loss of their sea ice habitat associated with climatic warming. We used location data from female polar bears fit with satellite radio collars to compare land use patterns in the Chukchi Sea between two periods (1986-1995 and 2008-2013) when substantial summer sea-ice loss occurred. In both time periods, polar bears predominantly occupied sea-ice, although land was used during the summer sea-ice retreat and during the winter for maternal denning. However, the proportion of bears on land for > 7 days between August and October increased between the two periods from 20.0% to 38.9%, and the average duration on land increased by 30 days. The majority of bears that used land in the summer and for denning came to Wrangel and Herald Islands (Russia), highlighting the importance of these northernmost land habitats to Chukchi Sea polar bears. Where bears summered and denned, and how long they spent there, was related to the timing and duration of sea ice retreat. Our results are consistent with other studies supporting increased land use as a common response of polar bears to sea-ice loss. Implications of increased land use for Chukchi Sea polar bears are unclear, because a recent study observed no change in body condition or reproductive indices between the two periods considered here. This result suggests that the ecology of this region may provide a degree of resilience to sea ice loss. However, projections of continued sea ice loss suggest that polar bears in the Chukchi Sea and other parts of the Arctic may increasingly use land habitats in the future, which has the potential to increase nutritional stress and human-polar bear interactions. PMID:26580809

  10. Full-field predictions of ice dynamic recrystallisation under simple shear conditions

    NASA Astrophysics Data System (ADS)

    Llorens, Maria-Gema; Griera, Albert; Bons, Paul D.; Lebensohn, Ricardo A.; Evans, Lynn A.; Jansen, Daniela; Weikusat, Ilka

    2016-09-01

    Understanding the flow of ice on the microstructural scale is essential for improving our knowledge of large-scale ice dynamics, and thus our ability to predict future changes of ice sheets. Polar ice behaves anisotropically during flow, which can lead to strain localisation. In order to study how dynamic recrystallisation affects to strain localisation in deep levels of polar ice sheets, we present a series of numerical simulations of ice polycrystals deformed under simple-shear conditions. The models explicitly simulate the evolution of microstructures using a full-field approach, based on the coupling of a viscoplastic deformation code (VPFFT) with dynamic recrystallisation codes. The simulations provide new insights into the distribution of stress, strain rate and lattice orientation fields with progressive strain, up to a shear strain of three. Our simulations show how the recrystallisation processes have a strong influence on the resulting microstructure (grain size and shape), while the development of lattice preferred orientations (LPO) appears to be less affected. Activation of non-basal slip systems is enhanced by recrystallisation and induces a strain hardening behaviour up to the onset of strain localisation and strain weakening behaviour. Simulations demonstrate that the strong intrinsic anisotropy of ice crystals is transferred to the polycrystalline scale and results in the development of strain localisation bands than can be masked by grain boundary migration. Therefore, the finite-strain history is non-directly reflected by the final microstructure. Masked strain localisation can be recognised in ice cores, such as the EDML, from the presence of stepped boundaries, microshear and grains with zig-zag geometries.

  11. Increased land use by Chukchi Sea polar bears in relation to changing sea ice conditions

    USGS Publications Warehouse

    Rode, Karyn D.; Wilson, Ryan R.; Regehr, Eric V.; St. Martin, Michelle; Douglas, David; Olson, Jay

    2015-01-01

    Recent observations suggest that polar bears (Ursus maritimus) are increasingly using land habitats in some parts of their range, where they have minimal access to their preferred prey, likely in response to loss of their sea ice habitat associated with climatic warming. We used location data from female polar bears fit with satellite radio collars to compare land use patterns in the Chukchi Sea between two periods (1986–1995 and 2008–2013) when substantial summer sea-ice loss occurred. In both time periods, polar bears predominantly occupied sea-ice, although land was used during the summer sea-ice retreat and during the winter for maternal denning. However, the proportion of bears on land for > 7 days between August and October increased between the two periods from 20.0% to 38.9%, and the average duration on land increased by 30 days. The majority of bears that used land in the summer and for denning came to Wrangel and Herald Islands (Russia), highlighting the importance of these northernmost land habitats to Chukchi Sea polar bears. Where bears summered and denned, and how long they spent there, was related to the timing and duration of sea ice retreat. Our results are consistent with other studies supporting increased land use as a common response of polar bears to sea-ice loss. Implications of increased land use for Chukchi Sea polar bears are unclear, because a recent study observed no change in body condition or reproductive indices between the two periods considered here. This result suggests that the ecology of this region may provide a degree of resilience to sea ice loss. However, projections of continued sea ice loss suggest that polar bears in the Chukchi Sea and other parts of the Arctic may increasingly use land habitats in the future, which has the potential to increase nutritional stress and human-polar bear interactions.

  12. Increased Land Use by Chukchi Sea Polar Bears in Relation to Changing Sea Ice Conditions

    PubMed Central

    Rode, Karyn D.; Wilson, Ryan R.; Regehr, Eric V.; St. Martin, Michelle; Douglas, David C.; Olson, Jay

    2015-01-01

    Recent observations suggest that polar bears (Ursus maritimus) are increasingly using land habitats in some parts of their range, where they have minimal access to their preferred prey, likely in response to loss of their sea ice habitat associated with climatic warming. We used location data from female polar bears fit with satellite radio collars to compare land use patterns in the Chukchi Sea between two periods (1986–1995 and 2008–2013) when substantial summer sea-ice loss occurred. In both time periods, polar bears predominantly occupied sea-ice, although land was used during the summer sea-ice retreat and during the winter for maternal denning. However, the proportion of bears on land for > 7 days between August and October increased between the two periods from 20.0% to 38.9%, and the average duration on land increased by 30 days. The majority of bears that used land in the summer and for denning came to Wrangel and Herald Islands (Russia), highlighting the importance of these northernmost land habitats to Chukchi Sea polar bears. Where bears summered and denned, and how long they spent there, was related to the timing and duration of sea ice retreat. Our results are consistent with other studies supporting increased land use as a common response of polar bears to sea-ice loss. Implications of increased land use for Chukchi Sea polar bears are unclear, because a recent study observed no change in body condition or reproductive indices between the two periods considered here. This result suggests that the ecology of this region may provide a degree of resilience to sea ice loss. However, projections of continued sea ice loss suggest that polar bears in the Chukchi Sea and other parts of the Arctic may increasingly use land habitats in the future, which has the potential to increase nutritional stress and human-polar bear interactions. PMID:26580809

  13. Polar Bear Conservation Status in Relation to Projected Sea-ice Conditions

    NASA Astrophysics Data System (ADS)

    Regehr, E. V.

    2015-12-01

    The status of the world's 19 subpopulations of polar bears (Ursus maritimus) varies as a function of sea-ice conditions, ecology, management, and other factors. Previous methods to project the response of polar bears to loss of Arctic sea ice—the primary threat to the species—include expert opinion surveys, Bayesian Networks providing qualitative stressor assessments, and subpopulations-specific demographic analyses. Here, we evaluated the global conservation status of polar bears using a data-based sensitivity analysis. First, we estimated generation length for subpopulations with available data (n=11). Second, we developed standardized sea-ice metrics representing habitat availability. Third, we projected global population size under alternative assumptions for relationships between sea ice and subpopulation abundance. Estimated generation length (median = 11.4 years; 95%CI = 9.8 to 13.6) and sea-ice change (median = loss of 1.26 ice-covered days per year; 95%CI = 0.70 to 3.37) varied across subpopulations. Assuming a one-to-one proportional relationship between sea ice and abundance, the median percent change in global population size over three polar bear generations was -30% (95%CI = -35% to -25%). Assuming a linear relationship between sea ice and normalized estimates of subpopulation abundance, median percent change was -4% (95% CI = -62% to +50%) or -43% (95% CI = -76% to -20%), depending on how subpopulations were grouped and how inference was extended from relatively well-studied subpopulations (n=7) to those with little or no data. Our findings suggest the potential for large reductions in polar bear numbers over the next three polar bear generations if sea-ice loss due to climate change continues as forecasted.

  14. Simulation Model Development for Icing Effects Flight Training

    NASA Technical Reports Server (NTRS)

    Barnhart, Billy P.; Dickes, Edward G.; Gingras, David R.; Ratvasky, Thomas P.

    2003-01-01

    A high-fidelity simulation model for icing effects flight training was developed from wind tunnel data for the DeHavilland DHC-6 Twin Otter aircraft. First, a flight model of the un-iced airplane was developed and then modifications were generated to model the icing conditions. The models were validated against data records from the NASA Twin Otter Icing Research flight test program with only minimal refinements being required. The goals of this program were to demonstrate the effectiveness of such a simulator for training pilots to recognize and recover from icing situations and to establish a process for modeling icing effects to be used for future training devices.

  15. Systems and Techniques for Identifying and Avoiding Ice

    NASA Technical Reports Server (NTRS)

    Hansman, R. John

    1995-01-01

    In-flight icing is one of the most difficult aviation weather hazards facing general aviation. Because most aircraft in the general aviation category are not certified for flight into known icing conditions, techniques for identifying and avoiding in-flight ice are important to maintain safety while increasing the utility and dispatch capability which is part of the AGATE vision. This report summarizes a brief study effort which: (1) Reviewed current ice identification, forecasting, and avoidance techniques; (2) Assessed feasibility of improved forecasting and ice avoidance procedures; and (3) Identified key issues for the development of improved capability with regard to in-flight icing.

  16. Modeling Commercial Turbofan Engine Icing Risk With Ice Crystal Ingestion

    NASA Technical Reports Server (NTRS)

    Jorgenson, Philip C. E.; Veres, Joseph P.

    2013-01-01

    The occurrence of ice accretion within commercial high bypass aircraft turbine engines has been reported under certain atmospheric conditions. Engine anomalies have taken place at high altitudes that have been attributed to ice crystal ingestion, partially melting, and ice accretion on the compression system components. The result was degraded engine performance, and one or more of the following: loss of thrust control (roll back), compressor surge or stall, and flameout of the combustor. As ice crystals are ingested into the fan and low pressure compression system, the increase in air temperature causes a portion of the ice crystals to melt. It is hypothesized that this allows the ice-water mixture to cover the metal surfaces of the compressor stationary components which leads to ice accretion through evaporative cooling. Ice accretion causes a blockage which subsequently results in the deterioration in performance of the compressor and engine. The focus of this research is to apply an engine icing computational tool to simulate the flow through a turbofan engine and assess the risk of ice accretion. The tool is comprised of an engine system thermodynamic cycle code, a compressor flow analysis code, and an ice particle melt code that has the capability of determining the rate of sublimation, melting, and evaporation through the compressor flow path, without modeling the actual ice accretion. A commercial turbofan engine which has previously experienced icing events during operation in a high altitude ice crystal environment has been tested in the Propulsion Systems Laboratory (PSL) altitude test facility at NASA Glenn Research Center. The PSL has the capability to produce a continuous ice cloud which are ingested by the engine during operation over a range of altitude conditions. The PSL test results confirmed that there was ice accretion in the engine due to ice crystal ingestion, at the same simulated altitude operating conditions as experienced previously in

  17. Real-time aircraft structural damage identification with flight condition variations

    NASA Astrophysics Data System (ADS)

    Lew, Jiann-Shiun; Loh, Chin-Hsiung

    2012-04-01

    This paper presents a real-time structural damage identification method for aircraft with flight condition variations. The proposed approach begins by identifying the dynamic models under various test conditions from time-domain input/output data. A singular value decomposition technique is then used to characterize and quantify the parameter uncertainties from the identified models. The uncertainty coordinates, corresponding to the identified principal directions, of the identified models are computed, and the residual errors between the identified uncertainty coordinates and the estimated uncertainty coordinates of the health structure are used to identify damage status. A correlation approach is applied to identify damage type and intensity, based on the difference between the identified parameters and the estimated parameters of the healthy structure. The proposed approach is demonstrated by application to the Benchmark Active Controls Technology (BACT) wind-tunnel model.

  18. Simulation comparison of aircraft landing performance in foggy conditions aided by different UV sensors.

    PubMed

    Lavigne, Claire; Durand, Gérard; Roblin, Antoine

    2009-04-20

    In the atmosphere pointlike sources are surrounded by an aureole due to molecular and aerosol scattering. UV phase functions of haze droplets have a very important forward peak that limits signal angular spreading in relation to the clear atmosphere case where Rayleigh scattering predominates. This specific property can be exploited using solar blind UV source detection as an aircraft landing aid under foggy conditions. Two methods have been used to compute UV light propagation, based on the Monte Carlo technique and a semi-empirical approach. Results obtained after addition of three types of sensor and UV runway light models show that an important improvement in landing conditions during foggy weather could be achieved by use of a solar blind UV intensified CCD camera with two stages of microchannel plates.

  19. Model Forecast Skill and Sensitivity to Initial Conditions in the Seasonal Sea Ice Outlook

    NASA Technical Reports Server (NTRS)

    Blanchard-Wrigglesworth, E.; Cullather, R. I.; Wang, W.; Zhang, J.; Bitz, C. M.

    2015-01-01

    We explore the skill of predictions of September Arctic sea ice extent from dynamical models participating in the Sea Ice Outlook (SIO). Forecasts submitted in August, at roughly 2 month lead times, are skillful. However, skill is lower in forecasts submitted to SIO, which began in 2008, than in hindcasts (retrospective forecasts) of the last few decades. The multimodel mean SIO predictions offer slightly higher skill than the single-model SIO predictions, but neither beats a damped persistence forecast at longer than 2 month lead times. The models are largely unsuccessful at predicting each other, indicating a large difference in model physics and/or initial conditions. Motivated by this, we perform an initial condition sensitivity experiment with four SIO models, applying a fixed -1 m perturbation to the initial sea ice thickness. The significant range of the response among the models suggests that different model physics make a significant contribution to forecast uncertainty.

  20. The importance of spring atmospheric conditions for predictions of the Arctic summer sea ice extent

    NASA Astrophysics Data System (ADS)

    Kapsch, Marie-Luise; Graversen, Rune G.; Economou, Theodoros; Tjernström, Michael

    2014-07-01

    Recent studies have shown that atmospheric processes in spring play an important role for the initiation of the summer ice melt and therefore may strongly influence the September sea ice concentration (SSIC). Here a simple statistical regression model based on only atmospheric spring parameters is applied in order to predict the SSIC over the major part of the Arctic Ocean. By using spring anomalies of downwelling longwave radiation or atmospheric water vapor as predictor variables, correlation coefficients between observed and predicted SSIC of up to 0.5 are found. These skills of seasonal SSIC predictions are similar to those obtained using more complex dynamical forecast systems, despite the fact that the simple model applied here takes neither information of the sea ice state, oceanic conditions nor feedback mechanisms during summer into account. The results indicate that a realistic representation of spring atmospheric conditions in the prediction system plays an important role for the predictive skills of a model system.

  1. Homogeneous ice freezing temperatures and ice nucleation rates of aqueous ammonium sulfate and aqueous levoglucosan particles for relevant atmospheric conditions.

    PubMed

    Knopf, Daniel Alexander; Lopez, Miguel David

    2009-09-28

    Homogeneous ice nucleation from micrometre-sized aqueous (NH4)2SO4 and aqueous levoglucosan particles is studied employing the optical microscope technique. A new experimental method is introduced that allows us to control the initial water activity of the aqueous droplets. Homogeneous ice freezing temperatures and ice melting temperatures of these aqueous solution droplets, 10 to 80 microm in diameter, are determined. Homogeneous ice nucleation from aqueous (NH4)2SO4 particles 5-39 wt% in concentration and aqueous levoglucosan particles with initial water activities of 0.85-0.99 yield upper limits of the homogeneous ice nucleation rate coefficients of up to 1x10(10) cm(-3) s(-1). The experimentally derived homogeneous ice freezing temperatures and upper limits of the homogeneous ice nucleation rate coefficients are compared with corresponding predictions of the water-activity-based ice nucleation theory [T. Koop, B. P. Luo, A. Tsias and T. Peter, Nature, 2000, 406, 611]. It is found that the water-activity-based ice nucleation theory can capture the experimentally derived ice freezing temperatures and homogeneous ice nucleation rate coefficients of the aqueous (NH4)2SO4 and aqueous levoglucosan particles. However, the level of agreement between experimentally derived and predicted values, in particular for homogeneous ice nucleation rate coefficients, crucially depends on the extrapolation method to obtain water activities at corresponding freezing temperatures. It is suggested that the combination of experimentally derived ice freezing temperatures and homogeneous ice nucleation rate coefficients can serve as a better validation of the water-activity-based ice nucleation theory than when compared to the observation of homogeneous ice freezing temperatures alone. The atmospheric implications with regard to the application of the water-activity-based ice nucleation theory and derivation of maximum ice particle production rates are briefly discussed.

  2. 78 FR 12595 - Safety Zone for Ice Conditions; Baltimore Captain of the Port Zone

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-25

    ...) 366-9826. SUPPLEMENTARY INFORMATION: Table of Acronyms DHS Department of Homeland Security FR Federal... the January 17, 2008, issue of the Federal Register (73 FR 3316). 4. Public Meeting We do not now plan... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone for Ice Conditions; Baltimore Captain of...

  3. Optical-cell evidence for superheated ice under gas-hydrate-forming conditions

    USGS Publications Warehouse

    Stern, L.A.; Hogenboom, D.L.; Durham, W.B.; Kirby, S.H.; Chou, I.-Ming

    1998-01-01

    We previously reported indirect but compelling evidence that fine-grained H2O ice under elevated CH4 gas pressure can persist to temperatures well above its ordinary melting point while slowly reacting to form methane clathrate hydrate. This phenomenon has now been visually verified by duplicating these experiments in an optical cell while observing the very slow hydrate-forming process as the reactants were warmed from 250 to 290 K at methane pressures of 23 to 30 MPa. Limited hydrate growth occurred rapidly after initial exposure of the methane gas to the ice grains at temperatures well within the ice subsolidus region. No evidence for continued growth of the hydrate phase was observed until samples were warmed above the equilibrium H2O melting curve. With continued heating, no bulk melting of the ice grains or free liquid water was detected anywhere within the optical cell until hydrate dissociation conditions were reached (292 K at 30 MPa), even though full conversion of the ice grains to hydrate requires 6-8 h at temperatures approaching 290 K. In a separate experimental sequence, unreacted portions of H2O ice grains that had persisted to temperatures above their ordinary melting point were successfully induced to melt, without dissociating the coexisting hydrate in the sample tube, by reducing the pressure overstep of the equilibrium phase boundary and thereby reducing the rate of hydrate growth at the ice-hydrate interface. Results from similar tests using CO2 as the hydrate-forming species demonstrated that this superheating effect is not unique to the CH4-H2O system.

  4. Exergo-Economic Analysis of an Experimental Aircraft Turboprop Engine Under Low Torque Condition

    NASA Astrophysics Data System (ADS)

    Atilgan, Ramazan; Turan, Onder; Aydin, Hakan

    Exergo-economic analysis is an unique combination of exergy analysis and cost analysis conducted at the component level. In exergo-economic analysis, cost of each exergy stream is determined. Inlet and outlet exergy streams of the each component are associated to a monetary cost. This is essential to detect cost-ineffective processes and identify technical options which could improve the cost effectiveness of the overall energy system. In this study, exergo-economic analysis is applied to an aircraft turboprop engine. Analysis is based on experimental values at low torque condition (240 N m). Main components of investigated turboprop engine are the compressor, the combustor, the gas generator turbine, the free power turbine and the exhaust. Cost balance equations have been formed for all components individually and exergo-economic parameters including cost rates and unit exergy costs have been calculated for each component.

  5. Prediction of air temperature in the aircraft cabin under different operational conditions

    NASA Astrophysics Data System (ADS)

    Volavý, F.; Fišer, J.; Nöske, I.

    2013-04-01

    This paper deals with the prediction of the air temperature in the aircraft cabin by means of Computational Fluid Dynamics. The simulations are performed on the CFD model which is based on geometry and cabin interior arrangement of the Flight Test Facility (FTF) located at Fraunhofer IBP, Germany. The experimental test flights under three different cabin temperatures were done in FTF and the various data were gathered during these flights. Air temperature in the cabin was measured on probes located near feet, torso and head of each passenger and also surface temperature and air temperature distributed from inlets were measured. The data were firstly analysed in order to obtain boundary conditions for cabin surfaces and inlets. Then the results of air temperature from the simulations were compared with measured data. The suitability and accuracy of the CFD approach for temperature prediction is discussed.

  6. Investigation of the solar influence on clean and dusty CO2-ice under Martian conditions

    NASA Astrophysics Data System (ADS)

    Kaufmann, E.; Hagermann, A.; Wolters, S.

    2015-10-01

    CO2 is the main component of the Martian atmosphere. Therefore the polar caps are - depending on hemisphere and season - partially or totally covered with CO2-ice. In contrast to rock and soil surface layers, which absorb and reflect incoming solar radiation immediately at the surface, ices are partially transparent in the visible spectral range, while they are opaque in the infrared. These properties are responsible for the so-called "Solid- State Greenhouse Effect" (SSGE). The SSGE may have a major influence on the sublimation and recondensation of CO2 and its circulation in the Martian atmosphere. Our work will concentrate on the influence of the SSGE on CO2-ice under Martian like conditions.

  7. Importance of initial conditions in seasonal predictions of Arctic sea ice extent

    NASA Astrophysics Data System (ADS)

    Msadek, R.; Vecchi, G. A.; Winton, M.; Gudgel, R. G.

    2014-07-01

    We present seasonal predictions of Arctic sea ice extent (SIE) over the 1982-2013 period using two suites of retrospective forecasts initialized from a fully coupled ocean-atmosphere-sea ice assimilation system. High skill scores are found in predicting year-to-year fluctuations of Arctic SIE, with significant correlations up to 7 month ahead for September detrended anomalies. Predictions over the recent era, which coincides with an improved observational coverage, outperform the earlier period for most target months. We find, however, a degradation of skill in September during the last decade, a period of sea ice thinning in observations. The two prediction models, Climate Model version 2.1 (CM2.1) and Forecast-oriented Low Ocean Resolution (FLOR), share very similar ocean and ice component and initialization but differ by their atmospheric component. FLOR has improved climatological atmospheric circulation and sea ice mean state, but its skill is overall similar to CM2.1 for most seasons, which suggests a key role for initial conditions in predicting seasonal SIE fluctuations.

  8. Subglacial hydraulic conditions of the former Barents Sea Ice Sheet inferred from meltwater landforms

    NASA Astrophysics Data System (ADS)

    Shackleton, Calvin; Bjarnadóttir, Lilja; Winsborrow, Monica; Esteves, Mariana; Andreassen, Karin

    2016-04-01

    A large multibeam dataset acquired by the MAREANO programme covering over 24,000 km2 at 5 m horizontal resolution has uncovered abundant subglacial meltwater landforms in the central Barents Sea. These landforms provide unprecedented insights into the nature of hydrological systems operating at the bed of the former Barents Sea Ice Sheet, helping us to understand the subglacial environments of marine based ice sheets as a whole. Large sinuous features up to 3.5 km wide and over 40 km long, with depths up to 40 m are interpreted as braided tunnel valleys, which would have drained vast amounts of water at the base of the ice sheet. Dendritic channels are also common, up to 42 km long and 24 m deep, along with several anastomosing channels and numerous complex esker systems. These features document that a wide range of subglacial hydraulic conditions and a well-established meltwater system existed beneath the former Barents Sea Ice Sheet. In conjunction with mapping of glacial landforms, these meltwater features provide the basis for a reconstruction of the subglacial drainage systems in the central Barents Sea and their interaction with the dynamic activity of the overlying ice sheet.

  9. Heterogeneous ice nucleation activity of bacteria: new laboratory experiments at simulated cloud conditions

    NASA Astrophysics Data System (ADS)

    Möhler, O.; Georgakopoulos, D. G.; Morris, C. E.; Benz, S.; Ebert, V.; Hunsmann, S.; Saathoff, H.; Schnaiter, M.; Wagner, R.

    2008-04-01

    The ice nucleation activities of five different Pseudomonas syringae, Pseudomonas viridiflava and Erwinia herbicola bacterial species and of SnomaxTM were investigated in the temperature range between -5 and -15°C. Water suspensions of these bacteria were directly spray into the cloud chamber of the AIDA facility of Forschungszentrum Karlsruhe at a temperature of -5.7°. At this temperature, about 1% of the SnomaxTM cells induced freezing of the spray droplets before they evaporated in the cloud chamber. The other suspensions of living cells didn't induce any measurable ice concentration during spray formation at -5.7°. The remaining aerosol was exposed to typical cloud activation conditions in subsequent experiments with expansion cooling to about -11°C. During these experiments, the bacterial cells first acted as cloud condensation nuclei to form cloud droplets and then eventually acted as ice nuclei to freeze the droplets. The results indicate that the bacteria investigated in the present study are mainly ice active in the temperature range between -7 and -11°C with an INA fraction of the order of 10-4. The ice nucleation efficiency of SnomaxTM cells was much larger with an INA fraction of 0.2 at temperatures around -8°C.

  10. Heterogeneous ice nucleation activity of bacteria: new laboratory experiments at simulated cloud conditions

    NASA Astrophysics Data System (ADS)

    Möhler, O.; Georgakopoulos, D. G.; Morris, C. E.; Benz, S.; Ebert, V.; Hunsmann, S.; Saathoff, H.; Schnaiter, M.; Wagner, R.

    2008-10-01

    The ice nucleation activities of five different Pseudomonas syringae, Pseudomonas viridiflava and Erwinia herbicola bacterial species and of Snomax™ were investigated in the temperature range between -5 and -15°C. Water suspensions of these bacteria were directly sprayed into the cloud chamber of the AIDA facility of Forschungszentrum Karlsruhe at a temperature of -5.7°C. At this temperature, about 1% of the Snomax™ cells induced immersion freezing of the spray droplets before the droplets evaporated in the cloud chamber. The living cells didn't induce any detectable immersion freezing in the spray droplets at -5.7°C. After evaporation of the spray droplets the bacterial cells remained as aerosol particles in the cloud chamber and were exposed to typical cloud formation conditions in experiments with expansion cooling to about -11°C. During these experiments, the bacterial cells first acted as cloud condensation nuclei to form cloud droplets. Then, only a minor fraction of the cells acted as heterogeneous ice nuclei either in the condensation or the immersion mode. The results indicate that the bacteria investigated in the present study are mainly ice active in the temperature range between -7 and -11°C with an ice nucleation (IN) active fraction of the order of 10-4. In agreement to previous literature results, the ice nucleation efficiency of Snomax™ cells was much larger with an IN active fraction of 0.2 at temperatures around -8°C.

  11. Modeling of oil spills in ice conditions in the Gulf of finland on the basis of an operative forecasting system

    NASA Astrophysics Data System (ADS)

    Stanovoy, V. V.; Eremina, T. R.; Isaev, A. V.; Neelov, I. A.; Vankevich, R. E.; Ryabchenko, V. A.

    2012-11-01

    A brief description of the GULFOOS operative forecasting oceanographic system of the Gulf of Finland and the OilMARS operative forecasting oil spill model is presented. Special attention is focused on oil spill simulation in ice conditions. All the assumptions and parameterizations used are described. Modeling results of training simulations for the ice conditions of January 2011 are presented.

  12. Photochemical degradation of a brominated flame retardant (tetrabromobisphenol A) in ice under field and laboratory conditions

    NASA Astrophysics Data System (ADS)

    Waligroski, G.; Grannas, A. M.

    2013-12-01

    Studies of brominated flame retardants have raised awareness of their potential environmental impact as toxic compounds. Because these compounds are now globally distributed, including in the Polar Regions, it is important to assess their potential fate in the environment. It has been shown that active photochemistry occurs in sunlit snow and ice, but there is little information regarding potential photochemical degradation of brominated flame retardants in snow and ice. The purpose of this research is to investigate the direct and indirect photochemical transformation pathways of a widely used brominated flame retardant, tetrabromobisphenol A (TBBPA). We have conducted field-based experiments in Barrow, Alaska to investigate the potential photochemical degradation of TBBPA in snow and ice under environmentally-relevant conditions. Field-based results show that TBBPA is efficiently degraded under direct photolysis conditions in frozen aqueous samples under natural Barrow sunlight. In aqueous solution the light absorption properties of TBBPA are pH dependent. Therefore, the photodegradation of TBBPA in snow and ice will be highly pH dependent. Reactions that are pH dependent may be affected by the nature of the liquid-like layers in snow/ice as well as the presence of other solutes that may indirectly affect the local pH experienced by TBBPA in snow and ice samples. In order to establish how the effective pH of liquid-like regions in ice might impact the degradation of TBBPA, various salts (sodium chloride, sodium fluoride, sodium bromide, ammonium chloride, ammonium acetate and ammonium sulfate) were added to aqueous solutions of TBBPA. Upon freezing, these different salts will induce pH differences in the liquid-like regions of the sample due to a phenomenon known as the freezing potential. Observed reactivity differences upon addition of these salts will be evaluated and discussed. Additionally, the presence of natural dissolved organic matter (DOM), an effective

  13. Computational Fluid Dynamics-Icing: a Predictive Tool for In-Flight Icing Risk Management

    NASA Astrophysics Data System (ADS)

    Zeppetelli, Danial

    In-flight icing is a hazard that continues to afflict the aviation industry, despite all the research and efforts to mitigate the risks. The recurrence of these types of accidents has given renewed impetus to the development of advanced analytical predictive tools to study both the accretion of ice on aircraft components in flight, and the aerodynamic consequences of such ice accumulations. In this work, an in-depth analysis of the occurrence of in-flight icing accidents and incidents was conducted to identify high-risk flight conditions. To investigate these conditions more thoroughly, a computational fluid dynamics model of a representative airfoil was developed to recreate experiments from the icing wind tunnel that occurred in controlled flight conditions. The ice accumulations and resulting aerodynamic performance degradations of the airfoil were computed for a range or pitch angles and flight speeds. These simulations revealed substantial performance losses such as reduced maximum lift, and decreased stall angle. From these results, an icing hazard analysis tool was developed, using risk management principles, to evaluate the dangers of in-flight icing for a specific aircraft based on the atmospheric conditions it is expected to encounter, as well as the effectiveness of aircraft certification procedures. This method is then demonstrated through the simulation of in-flight icing scenarios based on real flight data from accidents and incidents. The risk management methodology is applied to the results of the simulations and the predicted performance degradation is compared to recorded aircraft performance characteristics at the time of the occurrence. The aircraft performance predictions and resulting risk assessment are found to correspond strongly to the pilot's comments as well as to the severity of the incident.

  14. Causal Factors and Adverse Conditions of Aviation Accidents and Incidents Related to Integrated Resilient Aircraft Control

    NASA Technical Reports Server (NTRS)

    Reveley, Mary S.; Briggs, Jeffrey L.; Evans, Joni K.; Sandifer, Carl E.; Jones, Sharon Monica

    2010-01-01

    The causal factors of accidents from the National Transportation Safety Board (NTSB) database and incidents from the Federal Aviation Administration (FAA) database associated with loss of control (LOC) were examined for four types of operations (i.e., Federal Aviation Regulation Part 121, Part 135 Scheduled, Part 135 Nonscheduled, and Part 91) for the years 1988 to 2004. In-flight LOC is a serious aviation problem. Well over half of the LOC accidents included at least one fatality (80 percent in Part 121), and roughly half of all aviation fatalities in the studied time period occurred in conjunction with LOC. An adverse events table was updated to provide focus to the technology validation strategy of the Integrated Resilient Aircraft Control (IRAC) Project. The table contains three types of adverse conditions: failure, damage, and upset. Thirteen different adverse condition subtypes were gleaned from the Aviation Safety Reporting System (ASRS), the FAA Accident and Incident database, and the NTSB database. The severity and frequency of the damage conditions, initial test conditions, and milestones references are also provided.

  15. Commercial aviation icing research requirements

    NASA Technical Reports Server (NTRS)

    Koegeboehn, L. P.

    1981-01-01

    A short range and long range icing research program was proposed. A survey was made to various industry and goverment agencies to obtain their views of needs for commercial aviation ice protection. Through these responsed, other additional data, and Douglas Aircraft icing expertise; an assessment of the state-of-the-art of aircraft icing data and ice protection systems was made. The information was then used to formulate the icing research programs.

  16. Icing: Accretion, Detection, Protection

    NASA Technical Reports Server (NTRS)

    Reinmann, John J.

    1994-01-01

    The global aircraft industry and its regulatory agencies are currently involved in three major icing efforts: ground icing; advanced technologies for in-flight icing; and tailplane icing. These three major icing topics correspondingly support the three major segments of any aircraft flight profile: takeoff; cruise and hold; and approach and land. This lecture addressess these three topics in the same sequence as they appear in flight, starting with ground deicing, followed by advanced technologies for in-flight ice protection, and ending with tailplane icing.

  17. A Method for Calculating the Heat Required for Windshield Thermal Ice Prevention Based on Extensive Flight Tests in Natural Icing Conditions

    NASA Technical Reports Server (NTRS)

    Jones, Alun R; Holdaway, George H; Steinmetz, Charles P

    1947-01-01

    An equation is presented for calculating the heat flow required from the surface of an internally heated windshield in order to prevent the formation of ice accretions during flight in specified icing conditions. To ascertain the validity of the equation, comparison is made between calculated values of the heat required and measured values obtained for test windshields in actual flights in icing conditions. The test windshields were internally heated and provided data applicable to two common types of windshield configurations; namely the V-type and the type installed flush with the fuselage contours. These windshields were installed on a twin-engine cargo airplane and the icing flights were conducted over a large area of the United States during the winters of 1945-46 and 1946-47. In addition to the internally heated windshield investigation, some test data were obtained for a windshield ice-prevention system in which heated air was discharged into the windshield boundary layer. The general conclusions resulting from this investigation are as follows: 1) The amount of heat required for the prevention of ice accretions on both flush- and V-type windshields during flight in specified icing conditions can be calculated with a degree of accuracy suitable for design purposes. 2) A heat flow of 2000 to 2500 Btu per hour per square foot is required for complete and continuous protection of a V-type windshield in fight at speeds up to 300 miles per hour in a moderate cumulus icing condition. For the same degree of protection and the same speed range, a value of 1000 Btu per hour per square foot suffices in a moderate stratus icing condition. 3) A heat supply of 1000 Btu per hour per square foot is adequate for a flush windshield located well aft of the fuselage stagnation region, at speeds up to 300 miles per hour, for flight in both stratus and moderate cumulus icing conditions. 4) The external air discharge system of windshield thermal ice prevention is thermally

  18. A methodology for hard/soft information fusion in the condition monitoring of aircraft

    NASA Astrophysics Data System (ADS)

    Bernardo, Joseph T.

    2013-05-01

    Condition-based maintenance (CBM) refers to the philosophy of performing maintenance when the need arises, based upon indicators of deterioration in the condition of the machinery. Traditionally, CBM involves equipping machinery with electronic sensors that continuously monitor components and collect data for analysis. The addition of the multisensory capability of human cognitive functions (i.e., sensemaking, problem detection, planning, adaptation, coordination, naturalistic decision making) to traditional CBM may create a fuller picture of machinery condition. Cognitive systems engineering techniques provide an opportunity to utilize a dynamic resource—people acting as soft sensors. The literature is extensive on techniques to fuse data from electronic sensors, but little work exists on fusing data from humans with that from electronic sensors (i.e., hard/soft fusion). The purpose of my research is to explore, observe, investigate, analyze, and evaluate the fusion of pilot and maintainer knowledge, experiences, and sensory perceptions with digital maintenance resources. Hard/soft information fusion has the potential to increase problem detection capability, improve flight safety, and increase mission readiness. This proposed project consists the creation of a methodology that is based upon the Living Laboratories framework, a research methodology that is built upon cognitive engineering principles1. This study performs a critical assessment of concept, which will support development of activities to demonstrate hard/soft information fusion in operationally relevant scenarios of aircraft maintenance. It consists of fieldwork, knowledge elicitation to inform a simulation and a prototype.

  19. Laboratory Investigation of Ice Formation and Elimination in the Induction System of a Large Twin-engine Cargo Aircraft

    NASA Technical Reports Server (NTRS)

    Colis, William D

    1947-01-01

    The icing characteristics, the de-icing rate with hot air, and the effect of impact ice on fuel metering and mixture distribution have been determined in a laboratory investigation of that part of the engine induction system consisting of a three-barrel injection-type carburetor and a supercharger housing with spinner-type fuel injection from an 18-cylinder radial engine used on a large twin-engine cargo airplane. The induction system remained ice-free at carburetor-air temperatures above 36 F regardless of the moisture content of the air. Between carburetor-air temperatures of 32 F and 36 F with humidity ratios in excess of saturation, serious throttling ice formed in the carburetor because of expansion cooling of the air; at carburetor-air temperatures below 32 F with humidity ratios in excess of saturation, serious impact-ice formations occurred, Spinner-type fuel injection at the entrance to the supercharger and heating of the supercharger-inlet elbow and the guide vanes by the warn oil in the rear engine housing are design features that proved effective in eliminating fuel-evaporation icing and minimized the formation of throttling ice below the carburetor. Air-flow recovery time with fixed throttle was rapidly reduced as the inlet -air wet -bulb temperature was increased to 55 F; further temperature increase produced negligible improvement in recovery time. Larger ice formations and lower icing temperatures increased the time required to restore proper air flow at a given wet-bulb temperature. Impact-ice formations on the entrance screen and the top of the carburetor reduced the over-all fuel-air ratio and increased the spread between the over-all ratio and the fuel-air ratio of the individual cylinders. The normal spread of fuel-air ratio was increased from 0.020 to 0.028 when the left quarter of the entrance screen was blocked in a manner simulating the blocking resulting from ice formations released from upstream duct walls during hot-air de-icing.

  20. Investigation of ice cloud microphysical properties of DCSs using aircraft in situ measurements during MC3E over the ARM SGP site

    NASA Astrophysics Data System (ADS)

    Wang, Jingyu; Dong, Xiquan; Xi, Baike

    2015-04-01

    Six deep convective systems (DCSs) with a total of 5589 five-second samples and a range of temperatures from -41°C to 0°C during the Midlatitude Continental Convective Clouds Experiment (MC3E) were selected to investigate the ice cloud microphysical properties of DCSs over the Department of Energy Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site. The ice cloud measurements of the DCS cases were made by the University of North Dakota Citation II research aircraft, and the ice cloud properties were derived through the following processes. First, the instances of supercooled liquid water in the ice-dominated cloud layers of DCSs have been eliminated using multisensor detection, including the Rosemount Icing Detector, King and Cloud Droplet Probes, as well as 2DC and Cloud Imaging Probe images. Then the Nevzorov-measured ice water contents (IWCs) at maximum diameter Dmax < 4000 µm are used as the best estimation to determine a new mass-dimensional relationship. Finally, the newly derived mass-dimensional relationship (a = 0.00365, b = 2.1) has been applied to a full spectrum of particle size distributions (PSDs, 120-30,000 µm) constructed from both 2DC and High-Volume Precipitation Spectrometer measurements to calculate the best-estimated IWCs of DCSs during MC3E. The averages of the total number concentrations (Nt), median mass diameter (Dm), maximum diameter (Dmax), and IWC from six selected cases are 0.035 cm-3, 1666 µm, 8841 µm, and 0.45 g m-3, respectively. The gamma-type-size distributions are then generated matching the observed PSDs (120-30,000 µm), and the fitted gamma parameters are compared with the observed PSDs through multimoment assessments including first moment (Dm), third moment (IWC), and sixth moment (equivalent radar reflectivity, Ze). For application of observed PSDs to the remote sensing community, a series of empirical relationships between fitted parameters and Ze values has been derived, and the bullet rosette

  1. Large-eddy simulation of three mixed-phase cloud events during ISDAC: Conditions for persistent heterogeneous ice formation

    NASA Astrophysics Data System (ADS)

    Savre, J.; Ekman, A. M. L.

    2015-08-01

    A Classical-Nucleation-Theory-based parameterization for heterogenous ice nucleation, including explicit dependencies of the nucleation rates on the number concentration, size, and composition of the ambient aerosol population, is implemented in a cloud-scale, large-eddy simulation model and evaluated against Arctic mixed-phase cloud events observed during Indirect and Semi-Direct Aerosol Campaign (ISDAC). An important feature of the parameterization is that the ice nucleation efficiency of each considered aerosol type is described using a contact angle distribution which evolves with time so that the model accounts for the inhibition of ice nucleation as the most efficient ice-forming particles are nucleated and scavenged. The model gives a reasonable representation of first-order (ice water paths) and second-order (ice crystal size distributions) ice microphysical properties. The production of new ice crystals in the upper part of the cloud, essential to guarantee sustained mixed-phase conditions, is found to be controlled mostly by the competition between radiative cooling (resulting in more aerosol particles becoming efficient ice nuclei as the temperature decreases), cloud-top entrainment (entraining fresh particles into the cloud), and nucleation scavenging of the ice+forming aerosol particles. The relative contribution of each process is mostly determined by the cloud-top temperature and the entrainment rates. Accounting for the evolution of the contact angle probability density function with time seems to be essential to capture the persistence of in-cloud ice production without having to, for example, increase the free tropospheric aerosol concentration. Although limited to only three cases and despite important limitations of the parameterization (e.g., the present version only considers dust and black carbon as potential ice nuclei), the results suggest that modeling the time evolution of the ice nuclei population ability to form ice is required to

  2. 76 FR 65103 - Special Conditions: Gulfstream Aerospace Corporation, Model GIV-X Airplane; Aircraft Electronic...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-20

    ... GIV-X Airplane; Aircraft Electronic System Security Protection From Unauthorized External Access... connectivity capabilities of the airplane's computer systems and networks, which may allow access by external..., including: 1. Flight-safety related control, communication, and navigation systems (aircraft control...

  3. A Real-Time Satellite-Based Icing Detection System

    NASA Technical Reports Server (NTRS)

    Minnis, Patrick; Smith, William L., Jr.; Nguyen, Louis; Khaiyer, Mandana M.; Spangenberg, Douglas A.; Heck, Patrick W.; Palikonda, Rabindra; Bernstein, Ben C.; McDonough, Frank

    2004-01-01

    Aircraft icing is one of the most dangerous weather conditions for general aviation. Currently, model forecasts and pilot reports (PIREPS) constitute much of the database available to pilots for assessing the icing conditions in a particular area. Such data are often uncertain or sparsely available. Improvements in the temporal and areal coverage of icing diagnoses and prognoses would mark a substantial enhancement of aircraft safety in regions susceptible to heavy supercooled liquid water clouds. The use of 3.9 microns data from meteorological satellite imagers for diagnosing icing conditions has long been recognized (e.g., Ellrod and Nelson, 1996) but to date, no explicit physically based methods have been implemented. Recent advances in cloud detection and cloud property retrievals using operational satellite imagery open the door for real-time objective applications of those satellite datasets for a variety of weather phenomena. Because aircraft icing is related to cloud macro- and microphysical properties (e.g., Cober et al. 1995), it is logical that the cloud properties from satellite data would be useful for diagnosing icing conditions. This paper describes the a prototype realtime system for detecting aircraft icing from space.

  4. Ice conditions on the Chesapeake Bay as observed from LANDSAT during the winters of 1977, 1978 and 1979

    NASA Technical Reports Server (NTRS)

    Foster, J. L.

    1980-01-01

    The LANDSAT observations during the winters of 1977, 1978 and 1979, which were unusually cold in the northeastern U.S. and in the Chesapeake Bay area, were evaluated. Abnormal atmospheric circulation patterns displaced cold polar air to the south, and as a result, the Chesapeake Bay experienced much greater than normal icing conditions during these 3 years. The LANDSAT observations of the Chesapeake Bay area during these winters demonstrate the satellite's capabilities to monitor ice growth and melt, to detect ice motions, and to measure ice extent.

  5. A Study of Large Droplet Ice Accretion in the NASA Lewis IRT at Near-Freezing Conditions. Part 2

    NASA Technical Reports Server (NTRS)

    Addy, Harold E., Jr.; Miller, Dean R.; Ide, Robert F.

    1997-01-01

    Results of experiments designed to determine the effects of large droplet ice accretion on a NACA 23012 wing section are presented. Using primarily an icing condition with a median volumetric diameter droplet size of 160 micron and a liquid water content of 0.82 grams per cubic meter, the effects of various air temperatures, angles of attack, and de-icer boot cycle interval times on ice accretion were studied. Measurements of aerodynamic performance penalties due to the ice accretions were made. Results were also compared with similar tests conducted with a Twin Otter wing section in Part 1 of this study. The form of the ice from the large droplet cloud varied as a function of air total temperature; particularly at the near-freezing temperatures of 28 F to 34 F. Changing boot cycle interval time did not prevent formation of an ice ridge. The most detrimental aerodynamic effects occurred at an air total temperature of 28 F.

  6. Monitoring Inland Ice Cover under All-weather Conditions with the Combined Use of Microwave and GOES-R Observations

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Key, J. R.; Wang, X.

    2010-12-01

    The cryosphere exists at all latitudes and in about one hundred countries. Not only does the cryosphere play a significant role in climate, but also it has profound socio-economic value, especially over inland water, including lakes and rivers, due to its role in water resources and its impact on transportation, fisheries, hunting, herding, and agriculture. A number of ice characterization algorithms have been improved and/or developed for the next generation Geostationary Operational Environmental Satellite (GOES-R) Advanced Baseline Imager (ABI), including ice identification, ice concentration, ice thickness and age, and ice motion. These products will play an important role in monitoring ice cover over inland water considering its high spatial, temporal, and spectral resolution. However, the effectiveness of such products is constrained by cloud cover. Lake ice products from microwave observations are less affected by clouds, but their quality is hindered by coarse spatial and temporal resolution as well as contamination by the land surface. Optimization of all-weather ice products from microwave observations, and ice products with higher spatial and temporal resolutions from GOES-R enables us to monitor the ice characteristics over the inland water surfaces, e.g., the Great Lakes, effectively in real time under all-weather conditions, and improves the products that are being developed for ABI. The combined used of both products provides accurate, timely information on ice characteristics over inland water surfaces to meet the needs of transportation and winter weather forecasting. An overview of the ice cover, concentration, and motion products for both GOES-R and microwave observation will be given, and case studies of combining both products for monitoring ice characteristics over inland water will be presented.

  7. Effect of Plant Species and Environmental Conditions on Ice Nucleation Activity of Pseudomonas syringae on Leaves.

    PubMed

    O'brien, R D; Lindow, S E

    1988-09-01

    Selected plant species and environmental conditions were investigated for their influences on expression of ice nucleation activity by 15 Pseudomonas syringae strains grown on plants in constant-temperature growth chamber studies. Ice nucleation frequencies (INFs), the fraction of cells that expressed ice nucleation at -5 or -9 degrees C, of individual strains varied greatly, both on plants and in culture. This suggests that the probability of frost injury, which is proportional to the number of ice nuclei on leaf surfaces, is strongly determined by the particular bacterial strains that are present on a leaf surface. The INFs of strains were generally higher when they were grown on plants than when they were grown in culture. In addition, INFs in culture did not correlate closely with INFs on plants, suggesting that frost injury prediction should be based on INF measurements of cells grown on plants rather than in culture. The relative INFs of individual strains varied with plant host and environment. However, none of seven plant species tested optimized the INFs of all 15 strains. Similarly, incubation for 48 h at near 100% relative humidity with short photoperiods did not always decrease the INF when compared with a 72 h, 40% relative humidity, long-photoperiod incubation. Pathogenic strains on susceptible hosts were not associated with higher or lower INFs relative to their INFs on nonsusceptible plant species. The ice nucleation activity of individual bacterial strains on plants therefore appears to be controlled by complex and interacting factors such as strain genotype, environment, and host plant species. PMID:16347741

  8. Reconstructing Holocene conditions under ice in the Ross Sea and in the Southern Ocean using barnacles

    NASA Astrophysics Data System (ADS)

    Burgess, S. N.; Henderson, G. M.; Hall, B. L.

    2009-12-01

    Paleoclimate archives that capture annual and subannual resolution marine conditions outside the tropics are not common but would be highly desirable. This study demonstrates the potential of barnacles for such purposes and applies them to paleoceanographic reconstruction under the McMurdo ice shelf and in the Southern Ocean. Most of the Bathylasma samples used in this study grew in the Ross Sea and range in age between modern samples (used for calibration) and Holocene samples which were collected on the surface of the McMurdo Ice Shelf, having been entrained at the grounding line and moved through the ice by surface ablation and further basal freezing. Like other barnacles, this species secretes a robust low-Mg calcite shell with distinct growth increments on the external surface indicating growth durations of several decades. Barnacle shells were subsampled at high resolution (60 μm) for δ18O and δ13C analysis and dated by 14C. Measured δ18O values indicate that Bathylasma calcifies close to equilibrium with ambient seawater and those of old (>200kyr) samples suggest little or no diagenesis. These features make barnacles a promising archive for reconstruction of past ocean conditions. Variations in barnacle δ18O within each plate and between plates reflect changes in δ18O of the seawater, and allow some assessment of the salinity under the ice shelf. Salinities are lowered by addition of meltwaters, but the barnacle data suggest this lowering does not go below 33‰. Salinity near the grounding line shows both temporal and spatial variability. These data indicate that Bathylasma can provide valuable paleoclimate information at subannual resolution for shallow/intermediate water depths and regions such as Antarctica that play an important role in the climate system. We are now exploring this potential to investigate intermediate water conditions in the South Pacific during the last glacial using samples from seamounts on the Macquarie Ridge and south of

  9. Neutrons for probing the ice nucleation on atmospheric soot particles

    NASA Astrophysics Data System (ADS)

    Demirdjian, B.; Tishkova, V.; Ferry, D.

    2012-11-01

    Soot resulting from combustion of kerosene in aircraft engines can act as condensation nuclei for water/ice in the atmosphere and promote the formation of contrails that turn into artificial cirrus clouds and affect the climate. The mechanisms of nucleation of water/ice particles are not well identified. Studies "in situ" are difficult to realize, so we try to determine by neutron diffraction the nucleation of water/ice adsorbed on soot collected at the outlet of an aircraft engine combustor within the conditions of the upper troposphere. The results are compared with those obtained on model laboratory soot. The comparison highlights the role of chemical impurities and structural defects of original aircraft engine soot on the nucleation of water/ice in atmospheric conditions.

  10. Experimental observation and assessment of ice conditions with a fixed-wing unmanned aerial vehicle over Yellow River, China

    NASA Astrophysics Data System (ADS)

    Lin, Jiayuan; Shu, Li; Zuo, Hang; Zhang, Baosen

    2012-01-01

    Due to its unique geographical location and regional climate, the Yellow River and its tributaries are prone to ice jams almost every spring. Ice jams can cause levees to burst, leading to severe flooding, property damage, and human casualties. Hence, there is an urgent need to carry out observations of ice conditions and make risk assessments of ice jam occurrence. Field observation is the most reliable technique, but it is usually too expensive and time-consuming, which has led to the evaluation of applied remote sensing for data capture and analysis. Owing to the factors of timeliness, image resolution, human safety, and cost, satellite or manned aerial remote sensing cannot fully meet the requirements of ice condition observation. An unmanned aerial vehicle (UAV) remote sensing system is proposed for the collection of river ice imagery, providing the benefits of low cost, flexible launch and landing logistics, safety, and appropriate hyperspatial image resolution. One Inner Mongolian segment of the Yellow River was chosen as a test area to demonstrate key technologies and specific procedures of observation and assessment of ice conditions using the UAV system. The specific UAV remote sensing system and its components are introduced along with the procedures of UAV operation and imagery acquisition. Image preprocessing techniques and ice information extraction are described in detail followed by analysis and risk assessment of the ice conditions based on the resulting panoramic imagery. Results prove the feasibility and effectiveness of applying the fixed-wing UAV system to rapid observation and risk assessment of ice jam formation over the Yellow River under harsh weather conditions including low temperatures and strong winds.

  11. Determining the necessary conditions for Martian cloud formation: Ice nucleation in an electrodynamic balance (EDB)

    NASA Astrophysics Data System (ADS)

    Berlin, S.; Bauer, A. J.; Cziczo, D. J.

    2013-12-01

    The Martian atmosphere contains water ice clouds similar to Earth's cirrus clouds. These clouds influence the atmospheric temperature profile, alter the balance of incoming and outgoing radiation, and vertically redistribute water and mineral dust. Extrapolations of classical heterogeneous nucleation theory from Earth-like conditions to colder temperature and lower pressure regimes present in extraterrestrial atmospheres may be inaccurate, and thus hydrological models describing these regimes could lack physical meaning. In this project, we use an electrodynamic balance (EDB) to levitate individual aerosol particles and study their freezing properties. We test previously characterized aerosols such as Arizona Test Dust (ATD) and sodium chloride (NaCl). Then, we examine the less well-studied Mojave Mars Simulant (MMS) dust, which mimics the composition and size of dust particles found in the Martian atmosphere. A relative humidity, temperature, and inert atmosphere are utilized to emulate conditions found in the Martian atmosphere. We will discuss the supersaturations under which heterogeneous ice nucleation occurs on surrogate Martian ice nuclei at various temperatures.

  12. Aerodynamic Performance Degradation Induced by Ice Accretion. PIV Technique Assessment in Icing Wind Tunnel

    NASA Astrophysics Data System (ADS)

    Gregorio, Fabrizio De

    The aim of the present chapter is to consider the use of PIV technique in an industrial icing wind tunnel (IWT) and the potentiality/advantages of applying the PIV technique to this specific field. The purpose of icing wind tunnels is to simulate the aircraft flight condition through cloud formations. In this operational condition ice accretions appear on the aircraft exposed surfaces due to the impact of the water droplets present in the clouds and the subsequent solidification. The investigation of aircraft aerodynamic performances and flight safety in icing condition is a fundamental aspect in the phase of design, development and certification of new aircrafts. The description of this unusual ground testing facility is reported. The assessment of PIV in CIRA-IWT has been investigated. Several technological problems have been afforded and solved by developing the components of the measurement system, such as the laser system and the recording apparatus, both fully remotely controlled, equipped with several traversing mechanism and protected by the adverse environment conditions (temperature and pressure). The adopted solutions are described. Furthermore, a complete test campaign on a full-scale aircraft wing tip, equipped with moving slat and deicing system has been carried out by PIV. Two regions have been investigated. The wing leading-edge (LE) area has been studied with and without ice accretion and for different cloud characteristics. The second activitiy was aimed at the investigation of the wing-wake behavior. The measurements were aimed to characterize the wake for the model in cruise condition without ice formation and during the ice formation.

  13. Biological ice nuclei at tropospheric cloud heights: potential conditioning of precipitation

    NASA Astrophysics Data System (ADS)

    Stopelli, Emiliano; Conen, Franz; Alewell, Christine; Morris, Cindy

    2014-05-01

    Different substances present in the atmosphere enhance the aggregation of water molecules into ice structures, but particularly effective seem to be aerosols of biological origin, active at temperatures up to -2°C. Yet, the relevance of biological ice nucleation for cloud processes, such as initiating precipitation, remains ambiguous. We try to understand the meteorological conditions and the environmental factors controlling the abundance of biological ice nuclei (IN) in precipitation. One full year of observations has been carried out at the High Altitude Research station of Jungfraujoch, in the Swiss Alps, 3580 m a.s.l. Fresh snow was collected each month and analysed immediately on site for the concentration of IN active at temperatures warmer than -12°C. For this purpose we had developed an innovative system automatically recording freezing events of samples in closed tubes. Additional information was gained through the recording of meteorological parameters associated with the precipitation events, and the determination of stable isotopes (2H and 18O) and of bacterial concentrations (direct epifluorescence microscope counting, live/dead staining) in precipitation. Our analysis of the data suggests that the abundance of ice nuclei in snowfall is characterized not only by seasonality, but also by the geographical origin of precipitating air masses. Further, it seems that the more water an air mass has lost through previous precipitation, the smaller is the biological IN abundance in the remaining precipitation. Moreover, the loss of biological IN with precipitation seems to be much faster than that of other suspended particles in the same air mass, pointing towards a role of biological IN in conditioning the development of precipitation at its early stages.

  14. Effect of wearing an ice cooling jacket on repeat sprint performance in warm/humid conditions

    PubMed Central

    Duffield, R; Dawson, B; Bishop, D; Fitzsimons, M; Lawrence, S

    2003-01-01

    Objective: To examine the effect of cooling the skin with an ice jacket before and between exercise bouts (to simulate quarter and half time breaks) on prolonged repeat sprint exercise performance in warm/humid conditions. Methods: After an initial familiarisation session, seven trained male hockey players performed two testing sessions (seven days apart), comprising an 80 minute intermittent, repeat sprint cycling exercise protocol inside a climate chamber set at 30°C and 60% relative humidity. On one occasion a skin cooling procedure was implemented (in random counterbalanced order), with subjects wearing an ice cooling jacket both before (for five minutes) and in the recovery periods (2 x 5 min and 1 x 10 min) during the test. Measures of performance (work done and power output on each sprint), heart rates, blood lactate concentrations, core (rectal) and skin temperatures, sweat loss, perceived exertion, and ratings of thirst, thermal discomfort, and fatigue were obtained in both trials. Results: In the cooling condition, chest (torso) skin temperature, thermal discomfort, and rating of thirst were all significantly lower (p<0.05), but no significant difference (p>0.05) was observed between conditions for measures of work done, power output, heart rate, blood lactate concentration, core or mean skin temperature, perceived exertion, sweat loss, or ratings of fatigue. However, high effect sizes indicated trends to lowered lactate concentrations, sweat loss, and mean skin temperatures in the cooling condition. Conclusions: The intermittent use of an ice cooling jacket, both before and during a repeat sprint cycling protocol in warm/humid conditions, did not improve physical performance, although the perception of thermal load was reduced. Longer periods of cooling both before and during exercise (to lower mean skin temperature by a greater degree than observed here) may be necessary to produce such a change. PMID:12663361

  15. Bowhead whale body condition and links to summer sea ice and upwelling in the Beaufort Sea

    NASA Astrophysics Data System (ADS)

    George, John C.; Druckenmiller, Matthew L.; Laidre, Kristin L.; Suydam, Robert; Person, Brian

    2015-08-01

    We examined the response of bowhead whale (Balaena mysticetus) body condition to summer sea ice conditions and upwelling-favorable winds. We used a long-term dataset collected from whales of the Bering-Chukchi-Beaufort Seas (BCB) stock to estimate various body condition indices (BCI's) for individual whales that were harvested by Alaskan Eskimos. A series of offshore regions frequented by bowhead whales in summer were delineated and used to quantify interannual summertime environmental conditions including: (a) mean open water fraction, (b) duration of melt season, (c) date of continuous freeze-up, and (d) mean upwelling-favorable wind stress. Body condition was analyzed relative to these metrics for both the preceding summer feeding season and the previous three seasons combined. Our analysis indicates a significant increase in the long-term trend in an axillary girth-based body condition index (BCIG) over the study period (1989-2011). The increase in BCIG is likely associated with the trend in overall reduction of sea ice, including increased duration of open water, changes in upwelling potential (wind stress), and possibly higher primary production in the Pacific Arctic marine ecosystem favoring water-column invertebrates. We found strong significant positive correlations between BCIG and late summer open water fraction in the Beaufort Sea and smaller nearshore areas off the Mackenzie Delta and west of Banks Island. Additionally, BCIG was positively and significantly correlated with duration of melt season, later date of freeze-up in the Beaufort Sea, and upwelling-favorable winds on the Mackenzie shelf and west of Banks Island. A strong seasonal difference in BCI's was noted for subadult bowheads, presumably associated with summer feeding; however, yearlings were found to drop in BCI over at least the first summer after weaning. Our results indicate an overall increase in bowhead whale body condition and a positive correlation with summer sea ice loss over the

  16. A multi-column vertical mixing scheme to parameterize the heterogeneity of oceanic conditions under sea ice

    NASA Astrophysics Data System (ADS)

    Barthélemy, Antoine; Fichefet, Thierry; Goosse, Hugues; Madec, Gurvan

    2016-08-01

    The heterogeneity of ocean surface conditions associated with a spatially variable sea ice cover needs to be represented in models in order to represent adequately mixed layer processes and the upper ocean density structure. This study assesses the sensitivity of the ocean-sea ice model NEMO-LIM to a subgrid-scale representation of ice-ocean interactions. The sea ice component includes an ice thickness distribution, which provides heterogeneous surface buoyancy fluxes and stresses. A multi-column ocean scheme is developed to take them explicitly into account, by computing convection and turbulent vertical mixing separately in the open water/lead fraction of grid cells and below each ice thickness category. For the first time in a three-dimensional simulation, the distinct temperature and salinity profiles of the ocean columns are allowed to be maintained over several time steps. It is shown that the model response is highly sensitive to the homogenization time scale between the columns. If the latter are laterally mixed with time scales shorter than 10 h, subgrid-scale effects exist but the mean state is practically unaffected. For longer mixing time scales, in both hemispheres, the main impacts are reductions in under-ice mean mixed layer depths and in the summer melt of sea ice, following decreased oceanic heat flux at the ice base. Large changes in the open water temperature in summer suggest that the scheme could trigger important feedback processes in coupled simulations.

  17. A multi-column vertical mixing scheme to parameterize the heterogeneity of oceanic conditions under sea ice

    NASA Astrophysics Data System (ADS)

    Barthélemy, Antoine; Fichefet, Thierry; Goosse, Hugues; Madec, Gurvan

    2016-04-01

    The heterogeneity of ocean surface conditions associated to a spatially variable sea ice cover needs to be represented in models in order to represent adequately mixed layer processes and the upper ocean density structure. This study assesses the sensitivity of the ocean-sea ice model NEMO-LIM to a subgrid-scale representation of ice-ocean interactions. The sea ice component includes an ice thickness distribution, which provides heterogeneous surface buoyancy fluxes and stresses. A multi-column ocean scheme is developed to take them explicitly into account, by computing convection and turbulent vertical mixing separately in the open water/lead fraction of grid cells and below each ice thickness category. For the first time in a three-dimensional simulation, the distinct temperature and salinity profiles of the ocean columns are allowed to be maintained over several time steps. It is shown that, if columns are laterally mixed with homogenization time scales shorter than 10 h, subgrid-scale effects exists but the model mean state is practically unaffected. For longer mixing time scales, in both hemispheres, the main impacts are reductions in under-ice mean mixed layer depths and in the summer melt of sea ice, following decreased oceanic heat flux at the ice base. Large changes in the open water temperature in summer suggest that the scheme could trigger important feedback processes in coupled simulations.

  18. A Study of Large Droplet Ice Accretions in the NASA-Lewis IRT at Near-Freezing Conditions

    NASA Technical Reports Server (NTRS)

    Miller, Dean R.; Addy, Harold E. , Jr.; Ide, Robert F.

    1996-01-01

    This report documents the results of an experimental study on large droplet ice accretions which was conducted in the NASA-Lewis Icing Research Tunnel (IRT) with a full-scale 77.25 inch chord Twin-Otter wing section. This study was intended to: (1) document the existing capability of the IRT to produce a large droplet icing cloud, and (2) study the effect of various parameters on large droplet ice accretions. Results are presented from a study of the IRT's capability to produce large droplets with MVD of 99 and 160 microns. The effect of the initial water droplet temperature on the resultant ice accretion was studied for different initial spray bar air and water temperatures. The initial spray bar water temperature was found to have no discernible effect upon the large droplet ice accretions. Also, analytical and experimental results suggest that the water droplet temperature is very nearly the same as the tunnel ambient temperature, thus providing a realistic simulation of the large droplet natural icing condition. The effect of temperature, droplet size, airspeed, angle-of attack, flap setting and de-icer boot cycling time on ice accretion was studied, and will be discussed in this report. It was found that, in almost all of the cases studied, an ice ridge formed immediately aft of the active portion of the de-icer boot. This ridge was irregular in shape, varied in location, and was in some cases discontinuous due to aerodynamic shedding.

  19. Reconstructing Holocene conditions under the McMurdo Ice Shelf using Antarctic barnacle shells

    NASA Astrophysics Data System (ADS)

    Burgess, S. N.; Henderson, G. M.; Hall, B. L.

    2010-10-01

    This study evaluates the potential of barnacles for paleoceanographic reconstruction and, in particular, of the Antarctic species Bathylasma corolliforme to reconstruct past conditions under ice shelves. Like other barnacle species, this Antarctic barnacle secretes a robust low-Mg calcite shell with distinct growth increments on the external surface indicating growth over a number of years (30-50 in samples studied here). The Bathylasma samples used in this study grew in the Ross Sea and became entrained at the grounding line of a coastal ice shelf in McMurdo Sound, offering potential as an archive of changing conditions in this difficult to access environment under the McMurdo ice shelf. Nine barnacle shells were subsampled at high resolution (60 μm) for δ 18O and δ 13C analysis. These samples were dated with 14C and U-Th techniques, although the later did not yield useful age information due to open-system behaviour of barnacle calcite. Measured δ 18O values indicate that Bathylasma calcifies close to equilibrium with ambient seawater. One older sample (≈ 200 ka) has similar δ 18O and δ 13C values as the eight Holocene samples, suggesting that barnacle calcite is not prone to significant diagenesis in this setting. Apparent isotope equilibrium and lack of diagenesis make barnacles a promising archive for reconstruction of past ocean conditions. Cycles of δ 18O observed within each sample sometimes correlate with the external growth ridges, but not always, and have amplitudes of typically 0.6‰. This magnitude of variation suggests shell growth during a significant portion of the year, although it remains unclear whether growth continues throughout the year. However, the prominent growth bands suggest at least a signficant seasonal slowing in growth rate. Variations in barnacle δ 18O within each plate and between plates are too large to be caused by temperature, and instead reflect changes in δ 18O of the seawater, allowing some assessment of seawater

  20. Emission of energetic neutral atoms from water ice under Ganymede surface-like conditions

    NASA Astrophysics Data System (ADS)

    Wieser, Martin; Futaana, Yoshifumi; Barabash, Stas; Wurz, Peter

    2016-05-01

    The co-rotating plasma around Jupiter precipitates on the surfaces of the jovian moons, where it is not hindered by a local magnetic field. Precipitating ions lead to the emission of energetic neutral atoms, which are produced via backscattering and sputtering processes, from the surface. The European Space Agency's JUICE mission to Jupiter carries as part of the Particle Environment Package experiment an imaging energetic neutral atom spectrometer called the jovian Neutrals Analyzer (JNA). When it is in orbit around Ganymede, JNA will measure the energetic neutral atom flux emitted from the surface of Ganymede in the energy range from 10 eV to 3300 eV. The surface of Ganymede consists of a large fraction of water ice. To characterize the expected energetic neutral atom fluxes from water ice due to precipitating jovian plasma, we impacted protons and singly charged oxygen ions with energies up to 33 keV on a salty water ice target kept at Ganymede surface conditions. Emitted energetic atoms were measured energy- and mass-resolved using the JNA prototype instrument. The data show high yields for energetic neutral atoms per incident ion in the JNA energy range. For incident protons, energetic neutral atom yields between 0.28 at 1 keV and ∼40 at 33 keV were observed. For incident singly charged oxygen ions, the observed energetic neutral atom yield ranged from 0.8 for at 3 keV to ∼170 at 23 keV.

  1. Energetic neutral atoms emitted from ice by ion bombardment under Ganymede surface conditions

    NASA Astrophysics Data System (ADS)

    Wieser, Martin; Barabash, Stas; Futaana, Yoshifumi; Wurz, Peter

    2013-04-01

    Magnetospheric or solar wind ions directly interacting with a planetary surface result in backscattering or sputtering of energetic neutral atoms. One example is the solar wind interaction with the surface of the Moon, where the produced energetic neutral atoms were observed by the Sub-keV Atom Reflecting Analyzer instrument (SARA) on Chandrayaan-1. At Jupiter, magnetospheric plasma interacts in a similar way with the surface of the Galilean moons. However, the emission of energetic neutral atoms from "dirty" ices as found e.g. on Ganymede's surface is poorly understood. We set up an experiment to study the ion to surface interaction under Ganymede surface environment conditions using the unique capabilities of the MEFISTO test facility at University of Bern. Ions of various species and energies up to 33 keV/q were impacted on a block of ice made from a mixture of water, NaCl and dry ice. The energetic neutral atoms produced by the interaction were detected with the prototype of the Jovian Neutrals Analyzer instrument (JNA.) JNA is proposed as part of the Particle Environment Package (PEP) for ESA's JUICE mission to Jupiter and instrument is based on the Energetic Energetic Neutral Atom instrument (ENA) built for the BepiColombo Magnetospheric Orbiter. We present energy spectra for different ion beam species and energetic neutral atom species combinations. The data show high yields for energetic neutral atoms up to the upper end of the instrument energy range of 3.3 keV. The energy spectra of the neutral atom flux emitted from the ice could only partially be fitted by the Sigmund-Thompson formula. In some cases, but not all, a Maxwellian distribution provides a reasonable description of the data.

  2. Basal conditions and ice dynamics inferred from radar-derived internal stratigraphy of the Northeast Greenland Ice Stream

    NASA Astrophysics Data System (ADS)

    Keisling, B. A.; Christianson, K. A.; Alley, R. B.; Peters, L. E.; Christian, J. E.; Anandakrishnan, S.; Riverman, K. L.; Muto, A.; Jacobel, R. W.

    2013-12-01

    We present radio-echo sounding (RES), global positioning system (GPS) and active source seismic data from the central portion of the Northeast Greenland Ice Stream ~150 km downstream from the onset of streaming flow, which likely initiates due to locally high geothermal flux (~1 W/m2) near the ice sheet summit. Our geophysical data show that ice stream extent is limited via a feedback between basal hydrology and ice sheet surface elevation change. Active-source seismic data reveal water-saturated till beneath the central trunk of streaming flow. Subglacial till becomes increasingly dewatered and consolidated toward the shear margins. We hypothesize that ice accelerates and thins as it flows into NEGIS, producing marginal troughs in surface topography. These troughs create steep gradients in the subglacial hydropotential that generate parallel slippery and sticky bands beneath the margins, which limit ice entrainment across the margin and thus restrict further widening. Complex steady-state folds in radar reflectors within the shear margins form due to the combined influence of geothermal flux, varying basal shear stress, flow convergence, and bands of variable basal friction. Our strain rate and flux analysis of radar internal layers indicates no major changes in flow dynamics during the past ~10,000 years. However, strain rate modeling suggests that steady-state basal shear heating produces plentiful meltwater beneath the central trunk of streaming flow in addition to that supplied by geothermal flux. This meltwater supports the basal lubrication necessary to maintain streaming flow and may allow remobilization of dewatered marginal till. While the main trunk of streaming flow is remarkably stable, complex processes occurring within the shear margins merit closer scrutiny. The feedback between surface elevation change and basal water routing could mobilize currently unconsolidated sediments in the margins and result in shifts in ice dynamics.

  3. Ice Accretions on a Swept GLC-305 Airfoil

    NASA Technical Reports Server (NTRS)

    Vargas, Mario; Papadakis, Michael; Potapczuk, Mark; Addy, Harold; Sheldon, David; Giriunas, Julius

    2002-01-01

    An experiment was conducted in the Icing Research Tunnel (IRT) at NASA Glenn Research Center to obtain castings of ice accretions formed on a 28 deg. swept GLC-305 airfoil that is representative of a modern business aircraft wing. Because of the complexity of the casting process, the airfoil was designed with three removable leading edges covering the whole span. Ice accretions were obtained at six icing conditions. After the ice was accreted, the leading edges were detached from the airfoil and moved to a cold room. Molds of the ice accretions were obtained, and from them, urethane castings were fabricated. This experiment is the icing test of a two-part experiment to study the aerodynamic effects of ice accretions.

  4. Multiyear study of the dependence of sea salt aerosol on wind speed and sea ice conditions in the coastal Arctic

    NASA Astrophysics Data System (ADS)

    May, N. W.; Quinn, P. K.; McNamara, S. M.; Pratt, K. A.

    2016-08-01

    Thinning of Arctic sea ice gives rise to ice fracturing and leads (areas of open water surrounded by sea ice) that are a potential source of sea salt aerosol. Atmospheric particle inorganic ion concentrations, local sea ice conditions, and meteorology at Barrow, AK, from 2006 to 2009, were combined to investigate the dependence of submicron (aerodynamic diameter < 1 µm) and supermicron (aerodynamic diameter 1-10 µm) sea salt mass concentrations on sea ice coverage and wind speed. Consistent with a wind-dependent source, supermicron sea salt mass concentrations increased in the presence of nearby leads and wind speeds greater than 4 m s-1. Increased supermicron and submicron sea salt chloride depletion was observed for periods of low winds or a lack of nearby open water, consistent with transported sea salt influence. Sea salt aerosol produced from leads has the potential to alter cloud formation, as well as the chemical composition of the Arctic atmosphere and snowpack.

  5. NASA's program on icing research and technology

    NASA Technical Reports Server (NTRS)

    Reinmann, John J.; Shaw, Robert J.; Ranaudo, Richard J.

    1989-01-01

    NASA's program in aircraft icing research and technology is reviewed. The program relies heavily on computer codes and modern applied physics technology in seeking icing solutions on a finer scale than those offered in earlier programs. Three major goals of this program are to offer new approaches to ice protection, to improve our ability to model the response of an aircraft to an icing encounter, and to provide improved techniques and facilities for ground and flight testing. This paper reviews the following program elements: (1) new approaches to ice protection; (2) numerical codes for deicer analysis; (3) measurement and prediction of ice accretion and its effect on aircraft and aircraft components; (4) special wind tunnel test techniques for rotorcraft icing; (5) improvements of icing wind tunnels and research aircraft; (6) ground de-icing fluids used in winter operation; (7) fundamental studies in icing; and (8) droplet sizing instruments for icing clouds.

  6. NASA's program on icing research and technology

    NASA Technical Reports Server (NTRS)

    Reinmann, John J.; Shaw, Robert J.; Ranaudo, Richard J.

    1989-01-01

    NASA's program in aircraft icing research and technology is reviewed. The program relies heavily on computer codes and modern applied physics technology in seeking icing solutions on a finer scale than those offered in earlier programs. Three major goals of this program are to offer new approaches to ice protection, to improve the ability to model the response of an aircraft to an icing encounter, and to provide improved techniques and facilities for ground and flight testing. The following program elements are reviewed: (1) new approaches to ice protection; (2) numerical codes for deicer analysis; (3) measurement and prediction of ice accretion and its effect on aircraft and aircraft components; (4) special wind tunnel test techniques for rotorcraft icing; (5) improvements of icing wind tunnels and research aircraft; (6) ground de-icing fluids used in winter operation; (7) fundamental studies in icing; and (8) droplet sizing instruments for icing clouds.

  7. Icing Sensor Probe

    NASA Technical Reports Server (NTRS)

    Emery, Edward; Kok, Gregory L.

    2002-01-01

    Aircraft icing is a serious safety problem for the general aviation and some commuter transport airplanes. There has been tremendous growth in the commuter aviation industry in the last few years, Since these type of aircraft generally operate at lower altitudes they consequently spend a far greater proportion of their time operating in icing conditions. For the past thirty years airborne and ground based facilities have relied primarily on two types of cloud physics instrumentation to measure the characteristics of icing clouds: hot wire liquid water content probes and laser based particle sizing probes for the measurement of water droplet size. The instrumentation is severely limited by the technology that was developed during the 1970's and is quite large in size. The goal of this research is to develop one instrument with a wide bandwidth, better response time, higher resolution, user selectability, and small and lightweight. NASA Glenn Research Center, Droplet Measurement Technology, and Meteorology Society of Canada have developed a collaborative effort to develop such an instrument. This paper describes the development and test results of the prototype Icing Sensor Probe.

  8. Insights into Interactions of Water Ice with Regolith under Simulated Martian Conditions.

    NASA Astrophysics Data System (ADS)

    Chittenden, Julie; Chevrier, V.; Sears, D. W.; Roe, L. A.; Bryson, K.; Billingsly, L.; Hanley, J.

    2006-09-01

    In order to understand the diffusion process of water vapor through regolith, we have investigated the sublimation process of subsurface ice under varying depths of JSC Mars-1 soil simulant under martian conditions. Measurements were made at 0oC and 5.25 Torr in a CO2 atmosphere. We corrected for variations in temperature of the ice and the difference in gravity of Mars in relation to the Earth. Our results show that for depths up to 40 mm the process is mainly diffusion controlled and that for thicker regolith layers, desorption becomes the main process. After correction for the effect of desorption, we observed a decrease in sublimation rate from 0.625 ± 0.073 mm.h-1 at 5 mm of soil to 0.187 ± 0.093 mm.h-1 for 200 mm of soil. To characterize the diffusion process, we use the Farmer model (1976), which hypothesizes that the sublimation rate is equal to the diffusion coefficient divided by the soil depth. The derived diffusion coefficient from this data is 2.52 ± 0.55 mm2.h-1, or 7.0 ± 1.5 x 10-10 m2.s-1. Knowing the diffusion coefficient in the regolith, we can calculate the survival time, κ, of a layer of ice under a regolith layer which is given by τ = liceL/D, where lice is the thickness of the ice layer. Using this equation, we find that a 10 cm-thick layer of ice buried under 1 m of regolith would last for more than 4 years at 0oC. Therefore, our study indicates that the transport of water through a regolith layer is a complex multi-faceted process that is readily quantified by laboratory investigations. This is especially important in interpreting previous theoretical models and in understanding in situ observations to be performed by martian landers such as Phoenix. The W.M. Keck Foundation funded this research.

  9. Use of ERTS data for mapping Arctic sea ice

    NASA Technical Reports Server (NTRS)

    Barnes, J. C. (Principal Investigator); Bowley, C. J.

    1973-01-01

    The author has identified the following significant results. Data from ERTS passes crossing the Bering Sea in early March have been correlated with ice observations collected in the Bering Sea Experiment (BESEX). On two flights of the NASA CV-990 aircraft, the ice conditions in the vicinity of St. Lawrence Island reported by the onboard observer are in close agreement with the ice conditions mapped from the corresponding ERTS imagery. The ice features identified in ERTS imagery and substantiated by the aerial observer include the locations of boundaries between areas consisting of mostly grey ice and of mostly first and multi-year ice, the existence of shearing leads, and the occurrence of open water with the associated development of stratus cloud streaks. The BESEX correlative ice formation verifies the potential of practical applications of ERTS data.

  10. Turning up the heat on aircraft structures. [design and analysis for high-temperature conditions

    NASA Technical Reports Server (NTRS)

    Dobyns, Alan; Saff, Charles; Johns, Robert

    1992-01-01

    An overview is presented of the current effort in design and development of aircraft structures to achieve the lowest cost for best performance. Enhancements in this area are focused on integrated design, improved design analysis tools, low-cost fabrication techniques, and more sophisticated test methods. 3D CAD/CAM data are becoming the method through which design, manufacturing, and engineering communicate.

  11. Mapping recent sea ice conditions in the Barents Sea using the proxy biomarker IP25: implications for palaeo sea ice reconstructions

    NASA Astrophysics Data System (ADS)

    Navarro-Rodriguez, Alba; Belt, Simon T.; Knies, Jochen; Brown, Thomas A.

    2013-11-01

    An analysis of the sea ice proxy IP25 and the open water phytoplankton indicator brassicasterol has been carried out for 93 surface sediments collected from the Barents Sea and some additional data from previous studies have been included to augment the analysis further. Consistent with a specific and selective sea ice diatom origin for IP25, this biomarker was identified in virtually all sediments from seasonally ice-covered locations, but was absent from the majority of sites beyond the maximum sea ice extent (MSIE) for the period 1983-2002. In contrast, brassicasterol was detected in virtually all sediments from the region and concentrations were not at all associated with the MSIE. Instead, more localised regions of brassicasterol concentrations were identified and these likely reflect different influences on production and deposition. When the IP25 and brassicasterol concentrations were combined together in the form of the previously proposed PBIP25 index, the aforementioned association between IP25 occurrence and the MSIE was clarified further and, in addition, provided more detailed descriptions of sea ice cover. In particular, PBIP25 data indicated seasonal sea ice or marginal ice zone conditions for the region of the Barents Sea within the MSIE according to previously defined PBIP25 ranges. We also amalgamated the biomarker data from the current study with those derived previously by Müller et al. (2011) and compared these larger datasets with satellite-derived mean spring sea ice concentrations. Significantly, although the correlation between the combined IP25 concentration dataset with the satellite data was very similar to that reported previously by Müller et al. (2011), the corresponding correlation using the PBIP25 values was poorer with the larger dataset and some possible reasons for this are discussed. Finally, in a small number of cases, IP25 was identified in sediments somewhat distal from the MSIE, and it is hypothesised that the occurrence

  12. Illumination Conditions at the Asteroid 4 Vesta: Implications for the Presence of Water Ice

    NASA Technical Reports Server (NTRS)

    Stubbs, Timothy J.; Wang, Yongli

    2011-01-01

    The mean illumination conditions and surface temperatures over one orbital period are calculated for the Asteroid 4 Vesta using a coarse digital elevation model produced from Hubble Space Telescope images. Even with the anticipated effects of finer-scale topography taken into account, it is unlikely that any significant permanently shadowed regions currently exist on Vesta due to its large axial tilt (approx. = 27deg). However, under present day conditions, it is predicted that about half of Vesta's surface has an average temperature of less than 145 K, which, based on previous thermal modeling of main belt asteroids, suggests that water ice could survive in the top few meters of the vestal regolith on billion-year timescales.

  13. The interaction of radio frequency electromagnetic fields with atmospheric water droplets and applications to aircraft ice prevention. Thesis

    NASA Technical Reports Server (NTRS)

    Hansman, R. J., Jr.

    1982-01-01

    The feasibility of computerized simulation of the physics of advanced microwave anti-icing systems, which preheat impinging supercooled water droplets prior to impact, was investigated. Theoretical and experimental work performed to create a physically realistic simulation is described. The behavior of the absorption cross section for melting ice particles was measured by a resonant cavity technique and found to agree with theoretical predictions. Values of the dielectric parameters of supercooled water were measured by a similar technique at lambda = 2.82 cm down to -17 C. The hydrodynamic behavior of accelerated water droplets was studied photograhically in a wind tunnel. Droplets were found to initially deform as oblate spheroids and to eventually become unstable and break up in Bessel function modes for large values of acceleration or droplet size. This confirms the theory as to the maximum stable droplet size in the atmosphere. A computer code which predicts droplet trajectories in an arbitrary flow field was written and confirmed experimentally. The results were consolidated into a simulation to study the heating by electromagnetic fields of droplets impinging onto an object such as an airfoil. It was determined that there is sufficient time to heat droplets prior to impact for typical parameter values. Design curves for such a system are presented.

  14. Some effects of grooved runway configurations on aircraft tire braking traction under flooded runway conditions

    NASA Technical Reports Server (NTRS)

    Byrdsong, T. A.

    1973-01-01

    An experimental investigation was conducted to study the effect of grooved runway configurations on aircraft tire braking traction on flooded runway surfaces. The investigation was performed, utilizing size 49 x 17, type VII, aircraft tires with an inflation pressure of 170 lb per square inch at ground speeds up to approximately 120 knots. The results of this investigation indicate that when the runway is flooded, grooved surfaces provide better braking traction than an ungrooved surface and, in general, the level of braking traction was found to improve as the tire bearing pressure was increased because of an increase in the groove area of either the surface or the tire tread. Rounding the groove edges tended to degrade the tire braking capability from that developed on the same groove configuration with sharp edges. Results also indicate that braking friction coefficients for the test tires and runway surfaces decreased as ground speed was increased because of the hydroplaning effects.

  15. Study to determine operational and performance criteria for STOL aircraft operating in low visibility conditions

    NASA Technical Reports Server (NTRS)

    Gorham, J. A.

    1978-01-01

    The operational and performance criteria for civil CTOL passenger-carrying airplanes landing in low visibilities depend upon the characteristics of the airplane, the nature and use of the ground and airborne guidance and control systems, and the geometry and lighting of the landing field. Based upon these criteria, FAA advisory circulars, airplane and equipment design characteristics, and airline operational and maintenance procedures were formulated. The documents are selected, described, and discussed in relationship to the potential low weather minima operation of STOL aircraft. An attempt is made to identify fundamental differences between CTOL and STOL aircraft characteristics which could impact upon existing CTOL documentation. Further study and/or flight experiments are recommended.

  16. Mapping Ice with Airborne Lasers

    NASA Video Gallery

    Determining whether polar ice quantities are growing or shrinking requires accurate and detailed measurements, year over year. To help make those measurements, IceBridge mission aircraft fire 3,000...

  17. Extreme variation in basal thermal conditions of the central Greenland Ice Sheet due to anomalous lithosphere structure

    NASA Astrophysics Data System (ADS)

    Rogozhina, Irina; Petrunin, Alexey; Vaughan, Alan P. M.; Kukkonen, Ilmo T.; Kaban, Mikhail K.; Koulakov, Ivan; Thomas, Maik

    2013-04-01

    At the Earth's surface, heat fluxes from the interior are generally insignificant when compared with fluxes from the sun and atmosphere; however, in areas permanently blanketed by ice these become very important. Modelling studies show that they are key to understanding the internal thermal structure of ice sheets and the distribution of melt water at their bases, information which is crucial for planning deep ice drilling campaigns and climate reconstructions. Unfortunately, the challenging conditions in ice-covered regions make measurement difficult in exactly the places where it is needed most. Until now, proxy methodologies have been considered best for determining geothermal heat flux (GHF) beneath ice sheets. Our method is to use a novel interdisciplinary approach, integrating a time-evolved climate-ice-lithosphere coupled model with a wide range of data such as direct ice-core measurements, past climate reconstructions and indirect estimates of the lithospheric thermal state. Here we show that the oldest (and thickest) part of the Greenland Ice Sheet (GIS) is strongly thermally influenced by both GHF increasing from west to east and glaciation-induced perturbations of the thermal structure of the upper crust. A pronounced lateral gradient in GHF across the Summit region of the GIS is due to anomalously thin lithosphere, which has only about 25 to 66% of the thickness typical for Archaean to early Proterozoic areas. Our findings suggest that the thermal basal conditions of the present-day central GIS are characterized by surprising rapid lateral variations in ice temperatures of up to 12°C along relatively small distances of 100 to 150 km. We reveal two areas of rapid basal melt in central Greenland, only one of which was previously predicted by ice-penetrating radar measurements and age-depth relations from internal layering (Fahnestock et al. [2001]). The endothermic phase transition associated with rapid basal ice melt is found to increase subglacial heat

  18. Subaqueous ice-contact fans: Depositional systems characterised by highly aggradational supercritical flow conditions

    NASA Astrophysics Data System (ADS)

    Lang, Joerg; Winsemann, Jutta

    2015-04-01

    Subaqueous ice-contact fans are deposited by high-energy plane-wall jets from subglacial conduits into standing water bodies. Highly aggradational conditions during flow expansion and deceleration allow for the preservation of bedforms related to supercritical flows, which are commonly considered rare in the depositional record. We present field examples from gravelly and sandy subaqueous ice-contact fan successions, which indicate that deposition by supercritical flows might be considered as a characteristic feature of these depositional systems. The studied successions were deposited in deep ice-dammed lakes, which formed along the margins of the Middle Pleistocene Scandinavian ice sheets across Northern Germany. The gravel-rich subaqueous fan deposits are dominated by large scour-fills (up to 25 m wide and 3 m) deep and deposits of turbulent hyperconcentrated flows, which are partly attributed to supercritical flow conditions (Winsemann et al., 2009). Scours (up to 4.5 m wide and 0.9 m deep) infilled by gravelly backsets are observed above laterally extensive erosional surfaces and are interpreted as deposits of cyclic steps. Laterally discontinuous beds of low-angle cross-stratified gravel are interpreted as antidune deposits. Downflow and up-section the gravel-rich deposits pass into sand-rich successions, which include deposits of chutes-and-pools, breaking antidunes, stationary antidunes and humpback dunes (Lang and Winsemann, 2013). Deposits of chutes-and-pools and breaking antidunes are characterised by scour-fills (up to 4 m wide and 1.2 m deep) comprising backsets or gently dipping sigmoidal foresets. Stationary antidune deposits consist of laterally extensive sinusoidal waveforms with long wavelengths (1-12 m) and low amplitudes (0.1-0.5 m), which formed under quasi-steady flows at the lower limit of the supercritical flow stage and high rates of sedimentation. Humpback dunes are characterised by divergent sigmoidal foresets and are interpreted as

  19. Sensible heat balance estimates of transient soil ice contents for freezing and thawing conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Soil ice content is an important component for winter soil hydrology. The sensible heat balance (SHB) method using measurements from heat pulse probes (HPP) is a possible way to determine transient soil ice content. In a previous study, in situ soil ice contents estimates with the SHB method were in...

  20. 14 CFR 121.341 - Equipment for operations in icing conditions.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... requirements relating to ice protection, or unless an airplane is a non-transport category airplane type certificated after December 31, 1964, that has the ice protection provisions that meet section 34 of appendix A... equipped with means for the prevention or removal of ice on windshields, wings, empennage, propellers,...

  1. Aircraft-Induced Hole Punch and Canal Clouds

    NASA Astrophysics Data System (ADS)

    Heymsfield, A. J.; Kennedy, P.; Massie, S. T.; Schmitt, C. G.; Wang, Z.; Haimov, S.; Rangno, A.

    2009-12-01

    The production of holes and channels in altocumulus clouds by two commercial turboprop aircraft is documented for the first time. An unprecedented data set combining in situ measurements from microphysical probes with remote sensing measurements from cloud radar and lidar, all operating from the NSF/NCAR C130 aircraft, as well as ground-based NOAA and CSU radars, is used to describe the radar/lidar properties of a hole punch cloud and channel and the ensuing ice microphysical properties and structure of the ice column that subsequently developed. Ice particle production by commercial turboprop aircraft climbing through clouds much warmer than the regions where contrails are produced has the potential to modify significantly the cloud microphysical properties and effectively seed them under some conditions. Jet aircraft may also be producing hole punch clouds when flying through altocumulus with supercooled droplets at heights lower than their normal cruise altitudes where contrails can form. Commercial aircraft therefore can generate ice and affect the clouds at temperatures as much as 30°C warmer than the -40°C contrail formation threshold temperature.

  2. Total-Pressure Distortion and Recovery of Supersonic Nose Inlet with Conical Centerbody in Subsonic Icing Conditions

    NASA Technical Reports Server (NTRS)

    Gelder, Thomas F

    1957-01-01

    Ice was formed on a full-scale unheated supersonic nose inlet in the NACA Lewis icing tunnel to determine its effect on compressor-face total-pressure distortion and recovery.Inlet angle of attack was varied from 0degrees to 12 degrees, free-stream Mach number from 0.17 to 0.28, and compressor-face Mach number from 0.10 to 0.47. Icing-cloud liquid-water content was varied from 0.65 to 1.8 grams per cubic meter at free-stream static air temperatures of 15 degrees and 0 degrees F. The addition of ice to the inlet components increased total-pressure-distortion levels and decreased recovery values compared withclear0air results, the losses increasing with time in ice. The combination of glaze ice, high corrected weight flow, and high angle of attack yielded the highest levels of distortion and lowest values of recovery. The general character of compressor-face distortion with an iced inlet was the same as that for the clean inlet, the total-pressure gradients being predominantly radial, with circumferential gradients occurring at angle of attack. At zero angle of attack, free-stream Mach number of 0.27, and a constant corrected weight flow of 150 pounds per second (compressor-face Mach number of 0.43), compressor-face total-pressure-distortion level increased from about 6 percent in clear air to 12 percent after 21 minutes of heavy glaze icing; concurrently, total-pressure recovery decreased from about 0.98 to 0.945. For the same operating conditions but with the inlet at 12 deg angle of attack, a change in distortion level occurred from about 9 percent in clear air to 14 percent after 2-1/4 minutes of icing, with a decrease in recovery from about 0.97 to 0.94.

  3. Future sea ice conditions in Western Hudson Bay and consequences for polar bears in the 21st century.

    PubMed

    Castro de la Guardia, Laura; Derocher, Andrew E; Myers, Paul G; Terwisscha van Scheltinga, Arjen D; Lunn, Nick J

    2013-09-01

    The primary habitat of polar bears is sea ice, but in Western Hudson Bay (WH), the seasonal ice cycle forces polar bears ashore each summer. Survival of bears on land in WH is correlated with breakup and the ice-free season length, and studies suggest that exceeding thresholds in these variables will lead to large declines in the WH population. To estimate when anthropogenic warming may have progressed sufficiently to threaten the persistence of polar bears in WH, we predict changes in the ice cycle and the sea ice concentration (SIC) in spring (the primary feeding period of polar bears) with a high-resolution sea ice-ocean model and warming forced with 21st century IPCC greenhouse gas (GHG) emission scenarios: B1 (low), A1B (medium), and A2 (high). We define critical years for polar bears based on proposed thresholds in breakup and ice-free season and we assess when ice-cycle conditions cross these thresholds. In the three scenarios, critical years occur more commonly after 2050. From 2001 to 2050, 2 critical years occur under B1 and A2, and 4 under A1B; from 2051 to 2100, 8 critical years occur under B1, 35 under A1B and 41 under A2. Spring SIC in WH is high (>90%) in all three scenarios between 2001 and 2050, but declines rapidly after 2050 in A1B and A2. From 2090 to 2100, the mean spring SIC is 84 (±7)% in B1, 56 (±26)% in A1B and 20 (±13)% in A2. Our predictions suggest that the habitat of polar bears in WH will deteriorate in the 21st century. Ice predictions in A1B and A2 suggest that the polar bear population may struggle to persist after ca. 2050. Predictions under B1 suggest that reducing GHG emissions could allow polar bears to persist in WH throughout the 21st century.

  4. Improvement in Simulation of Eurasian Winter Climate Variability with a Realistic Arctic Sea Ice Condition in an Atmospheric GCM

    NASA Technical Reports Server (NTRS)

    Lim, Young-Kwon; Ham, Yoo-Geun; Jeong, Jee-Hoon; Kug, Jong-Seong

    2012-01-01

    The present study investigates how much a realistic Arctic sea ice condition can contribute to improve simulation of the winter climate variation over the Eurasia region. Model experiments are set up using different sea ice boundary conditions over the past 24 years (i.e., 1988-2011). One is an atmospheric model inter-comparison (AMIP) type of run forced with observed sea-surface temperature (SST), sea ice, and greenhouse gases (referred to as Exp RSI), and the other is the same as Exp RSI except for the sea ice forcing, which is a repeating climatological annual cycle (referred to as Exp CSI). Results show that Exp RSI produces the observed dominant pattern of Eurasian winter temperatures and their interannual variation better than Exp CSI (correlation difference up to approx. 0.3). Exp RSI captures the observed strong relationship between the sea ice concentration near the Barents and Kara seas and the temperature anomaly across Eurasia, including northeastern Asia, which is not well captured in Exp CSI. Lagged atmospheric responses to sea ice retreat are examined using observations to understand atmospheric processes for the Eurasian cooling response including the Arctic temperature increase, sea-level pressure increase, upper-level jet weakening and cold air outbreak toward the mid-latitude. The reproducibility of these lagged responses by Exp RSI is also evaluated.

  5. The effects of atmospheric and oceanic conditions on the stability of ice bridges

    NASA Astrophysics Data System (ADS)

    Stelma, Sigourney Anne

    Ice bridges are arch-like ice structures that form in narrow passages and straits. These bridges play largely important roles in the circulation of Arctic sea ice. When an ice bridge is present in a strait, there is typically a stoppage of sea ice flow, and there generally little ice flow downstream from the bridge. Nares Strait, located between Ellesmere Island and Greenland, allows for Arctic sea ice to be exported into the Atlantic Ocean. Ice bridges typically form in Nares Strait, which causes a stoppage of this export. This stoppage allows for Arctic sea ice to grow thicker, which is important for our current climate. Building on studies that examined the formation of ice bridges, this study aims to model and analyze the destruction of ice bridges. Using CICE: The Los Alamos Sea Ice Model, ice bridges are modeled in an idealized strait that is geographically and dimensionally similar to Nares Strait. The bridges are allowed to strengthen for 7 days past their initial formation. Then various atmospheric and oceanic parameters are changed, to examine their effect on the stable ice bridges. All parameter changes are applied over the entire domain and are constant in time. Extreme temperatures are used to study the effect of temperature. Then various amounts of longwave and shortwave radiation are tested independently, combined with temperature and combined with each other and temperature. We found that air temperature alone isn't the driving mechanism in bridge disintegration. As for radiative forcing, long- wave radiation proves to have a stronger effect than shortwave radiation. In fact, when air temperature, longwave radiation and shortwave radiation are combined, longwave radiation is the most dominant factor in disintegrating the bridges, followed by air temperature. Wind and currents are also tested. A seasonal progression, from winter to summer, is also applied to stable ice bridges of different initial thicknesses. All bridges studied under the seasonal

  6. The Recent Nansen's Ice-Shelf Calving Event : Comparison with Meteo-Climatic and Marine Conditions.

    NASA Astrophysics Data System (ADS)

    Fusco, G.; Cannito, A. C. C.; Marinangeli, L.; Cardinale, M.; Pompilio, L.

    2015-12-01

    Ice shelves are important elements of the Cryosphere representing the interface between ice, atmosphere and ocean. They are also the mean to discharge ice from the interior ice sheets contributing to the continental ice mass balance. A sudden change in volume and extension of both ice shelves and floating glacier tongues can rapidly increase the ice streams speed and the ice sheets flow variability.The Nansen ice shelf represent a particular sensible interface between the floating ice and the Terra Nova Bay polynya, a sea area that remains ice-free for almost all the winter time , thus being one of the major responsible of the production of the Antarctic bottom water. Remote sensing technologies gave us the opportunity to observe and investigate on the formation and evolution of an incipient crevasse on the Nansen Ice Shelf, starting from 1999. The crack showed a steady and slow increase in length and rotation up to 2011 and then underwent an abrupt evolution. During the 2014 winter season, the crack reached its maximum elongation and the detachment of large tabular bergs seems to be very close. This should be the first observation of a detachment of large tabular bergs from the Nansen Ice Shelf since the beginning of satellite observations and is an opportunity to investigate complex processes. We analyzed the last ten years record of climate data over the Southern ocean to evaluate the relationships between the intense cyclonic activity, synoptic and mesoscale systems, ocean swells and calving events. We used ECMWF ERA-interim global atmospheric reanalysis model, Landsat images and in situ weather observations from AWS of the Italian Antarctic Program deployed over the Terra Nova Bay cost. Our preliminary results show a strong correlation between the occurrence of some anomalous meteorological configurations over the Southern Ocean and the sudden grow of the monitored crack in the ice shelf. If confirmed, together with this new arrangement of the cryosphere, some

  7. Low Ice Adhesion on Nano-Textured Superhydrophobic Surfaces under Supersaturated Conditions.

    PubMed

    Bengaluru Subramanyam, Srinivas; Kondrashov, Vitaliy; Rühe, Jürgen; Varanasi, Kripa K

    2016-05-25

    Ice adhesion on superhydrophobic surfaces can significantly increase in humid environments because of frost nucleation within the textures. Here, we studied frost formation and ice adhesion on superhydrophobic surfaces with various surface morphologies using direct microscale imaging combined with macroscale adhesion tests. Whereas ice adhesion increases on microtextured surfaces, a 15-fold decrease is observed on nanotextured surfaces. This reduction is because of the inhibition of frost formation within the nanofeatures and the stabilization of vapor pockets. Such "Cassie ice"-promoting textures can be used in the design of anti-icing surfaces. PMID:27150450

  8. Annealing condition influences thermal hysteresis of fungal type ice-binding proteins.

    PubMed

    Xiao, Nan; Hanada, Yuichi; Seki, Haruhiko; Kondo, Hidemasa; Tsuda, Sakae; Hoshino, Tamotsu

    2014-02-01

    The Antarctic sea ice diatom Navicular glaciei produced ice-binding protein (NagIBP) that is similar to the antifreeze protein (TisAFP) from snow mold Typhula ishikariensis. In the thermal hysteresis range of NagIBP, ice growth was completely inhibited. At the freezing point, the ice grew in a burst to 6 direction perdicular to the c-axis of ice crystal. This burst pattern is similar to TisAFP and other hyperactive AFPs. The thermal hysteresis of NagIBP and TisAFP could be increased by decreasing a cooling rate to allow more time for the proteins to bind ice. This suggests the possible second binding of proteins occurs on the ice surface, which might increase the hysteresises to a sufficient level to prevent freezing of the brine pockets which habitat of N. glaciei. The secondary ice binding was described as that after AFP molecules bind onto the flat ice plane irreversibly, which was based on adsorption-inhibition mechanism model at the ice-water interface, convex ice front was formed and overgrew during normal TH measurement (no annealing) until uncontrolled growth at the nonequilibrium freezing point. The results suggested that NagIBP is a hyperactive AFP that is expressed for freezing avoidance.

  9. Response of ice cover on shallow Arctic lakes to contemporary climate conditions: Numerical modeling and remote sensing data analysis

    NASA Astrophysics Data System (ADS)

    Duguay, C.; Surdu, C.; Brown, L.; Samuelsson, P.

    2012-04-01

    Lake ice cover has been shown to be a robust indicator of climate variability and change. Recent studies have demonstrated that break-up dates, in particular, have been occurring earlier in many parts of the Northern Hemisphere over the last 50 years in response to warmer climatic conditions in the winter and spring seasons. The impacts of trends in air temperature and winter precipitation over the last five decades and those projected by global climate models will affect the timing and duration of ice cover (and ice thickness) on Arctic lakes. This will likely, in turn, have an important feedback effect on energy, water, and biogeochemical cycling in various regions of the Arctic. In the case of shallow tundra lakes, many of which are less than 3-m deep, warmer climate conditions could result in a smaller fraction of lakes that freeze to their bed in winter since thinner ice covers are expected to develop. Shallow lakes of the coastal plain of northern Alaska, and other similar regions of the Arctic, have likely been experiencing changes in seasonal ice thickness (and phenology) over the last few decades but these have not yet been documented. This paper presents results from a numerical lake ice modeling experiment and the analysis of ERS-1/2 synthetic aperture radar (SAR) data to elucidate the response of ice cover (thickness, freezing to bed, and phenology) on shallow lakes of the North Slope of Alaska (NSA)to climate conditions over the last three decades. New downscaled data specific for the Arctic domain (at a resolution of 0.44 degrees using ERA Interim Reanalysis as boundary condition) produced by the Rossby Centre regional atmospheric model (RCA4) was used to force the Canadian Lake Ice Model (CLIMo) for the period 1979-2010. Output from CLIMo included freeze-up and break-up dates as well as ice thickness on a daily basis. ERS-1/2 data was used to map areas of shallow lakes that freeze to bed and when this happens (timing) in winter for the period 1991

  10. Boundary condition of grounding lines prior to collapse, Larsen-B Ice Shelf, Antarctica.

    PubMed

    Rebesco, M; Domack, E; Zgur, F; Lavoie, C; Leventer, A; Brachfeld, S; Willmott, V; Halverson, G; Truffer, M; Scambos, T; Smith, J; Pettit, E

    2014-09-12

    Grounding zones, where ice sheets transition between resting on bedrock to full floatation, help regulate ice flow. Exposure of the sea floor by the 2002 Larsen-B Ice Shelf collapse allowed detailed morphologic mapping and sampling of the embayment sea floor. Marine geophysical data collected in 2006 reveal a large, arcuate, complex grounding zone sediment system at the front of Crane Fjord. Radiocarbon-constrained chronologies from marine sediment cores indicate loss of ice contact with the bed at this site about 12,000 years ago. Previous studies and morphologic mapping of the fjord suggest that the Crane Glacier grounding zone was well within the fjord before 2002 and did not retreat further until after the ice shelf collapse. This implies that the 2002 Larsen-B Ice Shelf collapse likely was a response to surface warming rather than to grounding zone instability, strengthening the idea that surface processes controlled the disintegration of the Larsen Ice Shelf.

  11. Growth and Survival of Some Probiotic Strains in Simulated Ice Cream Conditions

    NASA Astrophysics Data System (ADS)

    Homayouni, A.; Ehsani, M. R.; Azizi, A.; Razavi, S. H.; Yarmand, M. S.

    A Completely Randomized Design (CRD) experiment was applied in triplicates to evaluate the survival of four probiotic strains in simulated ice cream conditions. The growth and survival rate of these probiotic strains (Lactobacillus acidophilus, Lactobacillus casei, Bifidobacterium bifidum and Bifidobacterium longum) in varying amount of sucrose (10, 15, 20 and 25%), oxygen scavenging components (0.05% L-cysteine and 0.05% L-ascorbate) and temperatures (4 and -20°C) during different periods of time (1, 2 and 3 months) were evaluated in MRS-broth medium. Optical density at 580 nm was used to measure growth. Lactobacilli strains proved to be highly resistant in comparison with Biffidobacteria strains. The viable cell number of Lactobacillus casei in different sucrose concentrations, different oxidoreduction potentials and refrigeration temperature was 1x1010, 2x108 and 5x107 cfu mL-1, respectively. Growth and survival rate of Lactobacillus casei showed to be the highest.

  12. Experimental ice shape and performance characteristics for a multi-element airfoil in the NASA Lewis Icing Research Tunnel

    NASA Technical Reports Server (NTRS)

    Berkowitz, Brian M.; Potapczuk, Mark G.; Namdar, Bahman S.; Langhals, Tammy J.

    1991-01-01

    A study of the ice accretion patterns and performance of characteristics of a multi-element airfoil was undertaken at the NASA-Lewis Icing Research Tunnel. Several configurations were examined to determine the ice shape and performance characteristics. The testing included glaze, rime, and mixed icing regimes. Tunnel cloud conditions were set to correspond to those typical of the operating environment for commercial transport aircraft. Measurements acquired included ice profile tracings and aerodynamic forces both during the accretion process and in a post-accretion evaluation over a range of angle of attack. Substantial ice accretions developed on the main wing, flaps, and slat surfaces. Force measurements indicate severe performance degradation, especially near CL max, for both light and heavy ice accretion. Frost was seen on the lower surface of the airfoil which was found to contribute significantly to the force components.

  13. High-speed imaging of the transient ice accretion process on a NACA 0012 airfoil

    NASA Astrophysics Data System (ADS)

    Waldman, Rye; Hu, Hui

    2014-11-01

    Ice accretion on aircraft wings poses a performance and safety threat as aircraft encounter supercooled droplets suspended in the cloud layer. The details of the ice accretion depend on the atmospheric conditions and the fight parameters. We present the measurement results of the experiments conducted in the Iowa State icing wind tunnel on a NACA 0012 airfoil to study the transient ice accretion process under varying icing conditions. The icing process on the wing consists of a complex interaction of water deposition, surface water transport, and freezing. The aerodynamics affects the water deposition, the heat and mass transport, and ice accumulation; meanwhile, the accumulating ice also affects the aerodynamics. High-speed video of the unsteady icing accretion process was acquired under controlled environmental conditions to quantitatively measure the transient water run back, rivulet formation, and accumulated ice growth, and the experiments show how varying the environmental conditions modifies the ice accretion process. Funding support from the Iowa Energy Center with Grant No. 14-008-OG and National Science Foundation (NSF) with Grant No. CBET-1064196 and CBET-1438099 is gratefully acknowledged.

  14. Effects of Contact Angle Hysteresis on Ice Adhesion and Growth over Superhydrophobic Surfaces under Dynamic Flow Conditions

    SciTech Connect

    Sarshar, Mohammad Amin; Swarctz, Christopher; Hunter, Scott Robert; Simpson, John T; Choi, Chang-Hwan

    2012-01-01

    In this paper, the iceophobic properties of superhydrophobic surfaces are investigated under dynamic flow conditions by using a closed loop low-temperature wind tunnel. Superhydrophobic surfaces were prepared by coating the substrates of aluminum and steel plates with nano-structured hydrophobic particles. The superhydrophobic plates along with uncoated control ones were exposed to an air flow of 12 m/s and 20 F accompanying micron-sized water droplets in the icing wind tunnel and the ice formation and accretion were probed by high-resolution CCD cameras. Results show that the superhydrophobic coatings significantly delay the ice formation and accretion even under the dynamic flow condition of the highly energetic impingement of accelerated super-cooled water droplets. It is found that there is a time scale for this phenomenon (delay of the ice formation) which has a clear correlation with the contact angle hysteresis and the length scale of surface roughness of the superhydrophobic surface samples, being the highest for the plate with the lowest contact angle hysteresis and finer surface roughness. The results suggest that the key parameter for designing iceophobic surfaces is to retain a low contact angle hysteresis (dynamic property) and the non-wetting superhydrophobic state under the hydrodynamic pressure of impinging droplets, rather than to only have a high contact angle (static property), in order to result in efficient anti-icing properties under dynamic conditions such as forced flows.

  15. SUCCESS Evidence for Cirrus Cloud Ice Nucleation Mechanisms

    NASA Technical Reports Server (NTRS)

    Jensen, Eric; Gore, Warren J. Y. (Technical Monitor)

    1997-01-01

    During the SUCCESS mission, several measurements were made which should improve our understanding of ice nucleation processes in cirrus clouds. Temperature and water vapor concentration were made with a variety of instruments on the NASA DC-8. These observations should provide accurate upper tropospheric humidities. In particular, we will evaluate what humidities are required for ice nucleation. Preliminary results suggest that substantial supersaturations frequently exist in the upper troposphere. The leading-edge region of wave-clouds (where ice nucleation occurs) was sampled extensively at temperatures near -40 and -60C. These observations should give precise information about conditions required for ice nucleation. In addition, we will relate the observed aerosol composition and size distributions to the ice formation observed to evaluate the role of soot or mineral particles on ice nucleation. As an alternative technique for determining what particles act as ice nuclei, numerous samples of aerosols inside ice crystals were taken. In some cases, large numbers of aerosols were detected in each crystal, indicating that efficient scavenging occurred. Analysis of aerosols in ice crystals when only one particle per crystal was detected should help with the ice nucleation issue. Direct measurements of the ice nucleating activity of ambient aerosols drawn into airborne cloud chambers were also made. Finally, measurements of aerosols and ice crystals in contrails should indicate whether aircraft exhaust soot particles are effective ice nuclei.

  16. New Icing Cloud Simulation System at the NASA Glenn Research Center Icing Research Tunnel

    NASA Technical Reports Server (NTRS)

    Irvine, Thomas B.; Oldenburg, John R.; Sheldon, David W.

    1999-01-01

    A new spray bar system was designed, fabricated, and installed in the NASA Glenn Research Center's Icing Research Tunnel (IRT). This system is key to the IRT's ability to do aircraft in-flight icing cloud simulation. The performance goals and requirements levied on the design of the new spray bar system included increased size of the uniform icing cloud in the IRT test section, faster system response time, and increased coverage of icing conditions as defined in Appendix C of the Federal Aviation Regulation (FAR), Part 25 and Part 29. Through significant changes to the mechanical and electrical designs of the previous-generation spray bar system, the performance goals and requirements were realized. Postinstallation aerodynamic and icing cloud calibrations were performed to quantify the changes and improvements made to the IRT test section flow quality and icing cloud characteristics. The new and improved capability to simulate aircraft encounters with in-flight icing clouds ensures that the 1RT will continue to provide a satisfactory icing ground-test simulation method to the aeronautics community.

  17. Promoting wildness in sandhill cranes conditioned to follow an ultralight aircraft

    USGS Publications Warehouse

    Duff, J.W.; Lishman, W.A.; Clark, D.A.; Gee, G.F.; Sprague, D.T.; Ellis, D.H.

    2001-01-01

    During the 1998 field season, we developed and tested a new protocol to teach sandhill cranes (Grus canadensis) to follow ultralight aircraft yet avoid humans. Although successful in teaching the cranes a migration route, our previous migration (1997) resulted in birds that were overly tame and sought association with humans. For this study, 16 sandhill cranes were costume-reared at USGS Patuxent Wildlife Research Center and transported to Ontario shortly before fledging. After the birds learned to follow the aircraft, 14 were transported to an isolated wintering site in South Carolina, 1300 km south of the training area. Twelve arrived safely. Eleven of 12 birds survived the winter. All of these 11 cranes moved north to Cape Hatteras in early May. Thereafter, 6 of the cranes were captured and translocated to northern New York state. The remaining 5 returned to South Carolina, autumn 1999. Prior to capture, although the cranes sometimes allowed humans to approach them, none of the cranes approached buildings or humans.

  18. Aerodynamic Classification of Swept-Wing Ice Accretion

    NASA Technical Reports Server (NTRS)

    Broeren, Andy; Diebold, Jeff; Bragg, Mike

    2013-01-01

    The continued design, certification and safe operation of swept-wing airplanes in icing conditions rely on the advancement of computational and experimental simulation methods for higher fidelity results over an increasing range of aircraft configurations and performance, and icing conditions. The current state-of-the-art in icing aerodynamics is mainly built upon a comprehensive understanding of two-dimensional geometries that does not currently exist for fundamentally three-dimensional geometries such as swept wings. The purpose of this report is to describe what is known of iced-swept-wing aerodynamics and to identify the type of research that is required to improve the current understanding. Following the method used in a previous review of iced-airfoil aerodynamics, this report proposes a classification of swept-wing ice accretion into four groups based upon unique flowfield attributes. These four groups are: ice roughness, horn ice, streamwise ice, and spanwise-ridge ice. For all of the proposed ice-shape classifications, relatively little is known about the three-dimensional flowfield and even less about the effect of Reynolds number and Mach number on these flowfields. The classifications and supporting data presented in this report can serve as a starting point as new research explores swept-wing aerodynamics with ice shapes. As further results are available, it is expected that these classifications will need to be updated and revised.

  19. (abstract) Variations in Polarimetric Backscatter of Saline Ice Grown Under Diurnal Thermal Cycling Condition

    NASA Technical Reports Server (NTRS)

    Nghiem, S. V.; Kwok, R.; Yueh, S. H.; Kong, J. A.; Hsu, C. C.; Ding, K. H.

    1995-01-01

    An experiment was carried out in January 1994 at the Geophysical Research Facility in the Cold Regions Research and Engineering Laboratory. To investigate effects on polarimetric scattering signatures of sea ice growth under diurnal temperature variations, an ice sheet was grown for 2.5 days for the thickness of 10 cm and a polarimetric radar operating at C-band was used to obtain backscattering data in conjunction with ice-characterization measurements. The ice sheet was grown in the late morning of January 19, 1994. The initial growth rate was slow due to high insolation and temperature. As the air temperature dropped during the night, the growth rate increased significantly. The air temperature changed drastically from about -10(deg)C to -35(deg)C between day and night. The temperature cycle was repeated during the next day and the growth rate varied in the same manner. The surface of the ice was partially covered by frost flowers and the areal coverage increased as the ice became thicker. Throughout the ice growth duration of 2.5 days, polarimetric backscatter data were collected at roughly every centimeter of ice growth. For each set of radar measurements of saline ice, a set of calibration measurements was carried out with trihedrial corner reflectors and a metallic sphere. Measured polarimetric backscattering coefficients of the ice sheet reveal a strong correlation between radar data and temperature variations. As the temperature increased (decreased), the backscatter increased (decreased) correspondingly. From the ice-characterization data, temperatures of the air, at the ice-air interface, and in the ice layer had the same variation trend. Another interesting experimental observation is that the salinity measured as a function of ice depth from a sample of 10-cm thich ice indicated that the salinity variations had a similar cycle as the temperature; i.e., the salinity profile recorded the history of the temperature variations. Characterization data of the

  20. Maximum Evaporation Rates of Water Droplets Approaching Obstacles in the Atmosphere Under Icing Conditions

    NASA Technical Reports Server (NTRS)

    Lowell, H. H.

    1953-01-01

    When a closed body or a duct envelope moves through the atmosphere, air pressure and temperature rises occur ahead of the body or, under ram conditions, within the duct. If cloud water droplets are encountered, droplet evaporation will result because of the air-temperature rise and the relative velocity between the droplet and stagnating air. It is shown that the solution of the steady-state psychrometric equation provides evaporation rates which are the maximum possible when droplets are entrained in air moving along stagnation lines under such conditions. Calculations are made for a wide variety of water droplet diameters, ambient conditions, and flight Mach numbers. Droplet diameter, body size, and Mach number effects are found to predominate, whereas wide variation in ambient conditions are of relatively small significance in the determination of evaporation rates. The results are essentially exact for the case of movement of droplets having diameters smaller than about 30 microns along relatively long ducts (length at least several feet) or toward large obstacles (wings), since disequilibrium effects are then of little significance. Mass losses in the case of movement within ducts will often be significant fractions (one-fifth to one-half) of original droplet masses, while very small droplets within ducts will often disappear even though the entraining air is not fully stagnated. Wing-approach evaporation losses will usually be of the order of several percent of original droplet masses. Two numerical examples are given of the determination of local evaporation rates and total mass losses in cases involving cloud droplets approaching circular cylinders along stagnation lines. The cylinders chosen were of 3.95-inch (10.0+ cm) diameter and 39.5-inch 100+ cm) diameter. The smaller is representative of icing-rate measurement cylinders, while with the larger will be associated an air-flow field similar to that ahead of an airfoil having a leading-edge radius

  1. Effect of Some Factors on Critical Condition of Ice Formation for Flowing Supercooled Organic Water Solution in Cooled Circular Tube

    NASA Astrophysics Data System (ADS)

    Inaba, Hideo; Miyahara, Satoshi; Takeya, Kengo

    Supercooling characteristics of three kinds of organic water solutions (D-Sorbitol, Glycerol, Glucose) in a forced flow were investigated experimentally. The critical condition of ice nucleation in a cooled circular tube was examined for concentration of water solution and cooling temperature under various Reynolds numbers. It was found that the flow velocity and cooling temperature conditions in a laminar flow region. However, in a turbulent flow region, the critical degree of supercooling was influenced by the flow velocity and cooling temperature. As a result, non-dimensional correlation equations for the critical condition of ice formation were derived in the laminar and turbulent flow region as a function of some non-dimensional parameters. While the ice making efficiency of D-Sorbitol water solution was measured under various Reynolds numbers and cooling temperature conditions on the stable supercooling condition. The ice making efficiency of supercooled organic water solution was influenced by the degree of the supercooling based on the mixed organic water solution temperature at the outlet of the inner tube.

  2. Evaluation of photogrammetric flight under icing conditions on March 23, 1978

    NASA Technical Reports Server (NTRS)

    Fuchs, W.; Kaluza, J.

    1981-01-01

    In a double passage through a route laid out in a stagnation zone of the Bavarian forest, it was found that the stagnation and attendant elevation increases the danger of icing. Conversely, it turned out that formation of precipitation reduces the icing intensity. A comparison of both factors showed: the reduction of ice formation through precipitation equals the increase due to stagnation, or even exceeds it.

  3. Transient effects of harsh luminous conditions on the visual performance of aviators in a civil aircraft cockpit.

    PubMed

    Yang, Biao; Lin, Yandan; Sun, Yaojie

    2013-03-01

    The aim of this work was to examine how harsh luminous conditions in a cockpit, such as lightning in a thunderstorm or direct sunlight immediately after an aircraft passes through clouds, may affect the visual performance of pilots, and how to improve it. Such lighting conditions can result in the temporary visual impairment of aviators, which may greatly increase the risk of accidents. Tests were carried out in a full-scale simulator cockpit in which two kinds of dynamic lighting scenes, namely pulse changed and step changed lighting, were used to represent harsh luminous conditions. Visual acuity (VA), reaction time (RT) and identification accuracy (IA) were recorded as dependent variables. Data analysis results indicate that standardized VA values decreased significantly in both pulsing and step conditions in comparison with the dark condition. Standardized RT values increased significantly in the step condition; on the contrary, less reaction time was observed in the pulsing condition. Such effects could be reduced by an ambient illumination provided by a fluorescent lamp in both conditions. The results are to be used as a principle for optimizing lighting design with a thunderstorm light.

  4. Transient effects of harsh luminous conditions on the visual performance of aviators in a civil aircraft cockpit.

    PubMed

    Yang, Biao; Lin, Yandan; Sun, Yaojie

    2013-03-01

    The aim of this work was to examine how harsh luminous conditions in a cockpit, such as lightning in a thunderstorm or direct sunlight immediately after an aircraft passes through clouds, may affect the visual performance of pilots, and how to improve it. Such lighting conditions can result in the temporary visual impairment of aviators, which may greatly increase the risk of accidents. Tests were carried out in a full-scale simulator cockpit in which two kinds of dynamic lighting scenes, namely pulse changed and step changed lighting, were used to represent harsh luminous conditions. Visual acuity (VA), reaction time (RT) and identification accuracy (IA) were recorded as dependent variables. Data analysis results indicate that standardized VA values decreased significantly in both pulsing and step conditions in comparison with the dark condition. Standardized RT values increased significantly in the step condition; on the contrary, less reaction time was observed in the pulsing condition. Such effects could be reduced by an ambient illumination provided by a fluorescent lamp in both conditions. The results are to be used as a principle for optimizing lighting design with a thunderstorm light. PMID:22858009

  5. Application of the JDL data fusion process model to hard/soft information fusion in the condition monitoring of aircraft

    NASA Astrophysics Data System (ADS)

    Bernardo, Joseph T.

    2014-05-01

    Hard/soft information fusion has been proposed as a way to enhance diagnostic capability for the condition monitoring of machinery. However, there is a limited understanding of where hard/soft information fusion could and should be applied in the condition monitoring of aircraft. Condition-based maintenance refers to the philosophy of performing maintenance when the need arises, based upon indicators of deterioration in the condition of the machinery. The addition of the multisensory capability of human cognition to electronic sensors may create a fuller picture of machinery condition. Since 1988, the Joint Directors of Laboratories (JDL) data fusion process model has served as a framework for information fusion research. Advances are described in the application of hard/soft information fusion in condition monitoring using terms that condition-based maintenance professionals in aviation will recognize. Emerging literature on hard/soft information fusion in condition monitoring is organized into the levels of the JDL data fusion process model. Gaps in the literature are identified, and the author's ongoing research is discussed. Future efforts will focus on building domain-specific frameworks and experimental design, which may provide a foundation for improving flight safety, increasing mission readiness, and reducing the cost of maintenance operations.

  6. Preliminary Analysis of X-Band and Ka-Band Radar for Use in the Detection of Icing Conditions Aloft

    NASA Technical Reports Server (NTRS)

    Reehorst, Andrew L.; Koenig, George G.

    2004-01-01

    NASA and the U.S. Army Cold Regions Research and Engineering Laboratory (CRREL) have an on-going activity to develop remote sensing technologies for the detection and measurement of icing conditions aloft. Radar has been identified as a strong tool for this work. However, since the remote detection of icing conditions with the intent to identify areas of icing hazard is a new and evolving capability, there are no set requirements for radar sensitivity. This work is an initial attempt to quantify, through analysis, the sensitivity requirements for an icing remote sensing radar. The primary radar of interest for cloud measurements is Ka-band, however, since NASA is currently using an X-band unit, this frequency is also examined. Several aspects of radar signal analysis were examined. Cloud reflectivity was calculated for several forms of cloud using two different techniques. The Air Force Geophysical Laboratory (AFGL) cloud models, with different drop spectra represented by a modified gamma distribution, were utilized to examine several categories of cloud formation. Also a fundamental methods approach was used to allow manipulation of the cloud droplet size spectra. And an analytical icing radar simulator was developed to examine the complete radar system response to a configurable multi-layer cloud environment. Also discussed is the NASA vertical pointing X-band radar. The radar and its data system are described, and several summer weather events are reviewed.

  7. Using memory for prior aircraft events to detect conflicts under conditions of proactive air traffic control and with concurrent task requirements.

    PubMed

    Bowden, Vanessa K; Loft, Shayne

    2016-06-01

    In 2 experiments we examined the impact of memory for prior events on conflict detection in simulated air traffic control under conditions where individuals proactively controlled aircraft and completed concurrent tasks. Individuals were faster to detect conflicts that had repeatedly been presented during training (positive transfer). Bayesian statistics indicated strong evidence for the null hypothesis that conflict detection was not impaired for events that resembled an aircraft pair that had repeatedly come close to conflicting during training. This is likely because aircraft altitude (the feature manipulated between training and test) was attended to by participants when proactively controlling aircraft. In contrast, a minor change to the relative position of a repeated nonconflicting aircraft pair moderately impaired conflict detection (negative transfer). There was strong evidence for the null hypothesis that positive transfer was not impacted by dividing participant attention, which suggests that part of the information retrieved regarding prior aircraft events was perceptual (the new aircraft pair "looked" like a conflict based on familiarity). These findings extend the effects previously reported by Loft, Humphreys, and Neal (2004), answering the recent strong and unanimous calls across the psychological science discipline to formally establish the robustness and generality of previously published effects. (PsycINFO Database Record PMID:27295467

  8. Using memory for prior aircraft events to detect conflicts under conditions of proactive air traffic control and with concurrent task requirements.

    PubMed

    Bowden, Vanessa K; Loft, Shayne

    2016-06-01

    In 2 experiments we examined the impact of memory for prior events on conflict detection in simulated air traffic control under conditions where individuals proactively controlled aircraft and completed concurrent tasks. Individuals were faster to detect conflicts that had repeatedly been presented during training (positive transfer). Bayesian statistics indicated strong evidence for the null hypothesis that conflict detection was not impaired for events that resembled an aircraft pair that had repeatedly come close to conflicting during training. This is likely because aircraft altitude (the feature manipulated between training and test) was attended to by participants when proactively controlling aircraft. In contrast, a minor change to the relative position of a repeated nonconflicting aircraft pair moderately impaired conflict detection (negative transfer). There was strong evidence for the null hypothesis that positive transfer was not impacted by dividing participant attention, which suggests that part of the information retrieved regarding prior aircraft events was perceptual (the new aircraft pair "looked" like a conflict based on familiarity). These findings extend the effects previously reported by Loft, Humphreys, and Neal (2004), answering the recent strong and unanimous calls across the psychological science discipline to formally establish the robustness and generality of previously published effects. (PsycINFO Database Record

  9. Determination of the Corrosive Conditions Present within Aircraft Lap-Splice Joints

    NASA Technical Reports Server (NTRS)

    Lewis, Karen S.; Kelly, Robert G.; Piascik, Robert S.

    1999-01-01

    The complexity of airframe structure lends itself to damage resulting from crevice corrosion. Fuselage lap-splice joints are a particularly important structural detail in this regard because of the difficulty associated with detection and measurement of corrosion in these occluded regions. The objective of this work is to develop a laboratory corrosion test protocol to identify the chemistry to which lap joints are exposed and to develop a model of the corrosion within the joints. A protocol for collecting and identifying the chemistry of airframe crevice corrosion has been developed. Capillary electrophoresis (CE) is used to identify the ionic species contained in corrosion product samples removed from fuselage lap splice joints. CE analysis has been performed on over sixty corrosion product samples removed from both civilian and military aircraft. Over twenty different ions have been detected. Measurements of pH of wetted corroded surfaces indicated an alkaline occluded solution. After determining the species present and their relative concentrations, the resultant solution was reproduced in bulk and electrochemical tests were performed to determine the corrosion rate. Electrochemical analyses of the behavior of AA2024-T3 in these solutions gave corrosion rates of up to 250 microns per year (10 mpy). Additional tests have determined the relative importance of each of the detected ions in model solutions used for future predictive tests. The statistically significant ions have been used to create a second generation solution. Laboratory studies have also included exposure tests involving artificial lap joints exposed to various simulated bulk and crevice environments. The extent and morphology of the attack in artificial lap joints has been compared to studies of corroded samples from actual aircraft. Other effects, such as temperature and potential, as well as the impact of the environment on fatigue crack growth have also been studied.

  10. New Spray Bar System Installed in NASA Lewis' Icing Research Tunnel

    NASA Technical Reports Server (NTRS)

    Irvine, Thomas B.

    1998-01-01

    NASA Lewis Research Center's Icing Research Tunnel (IRT) is the world's largest refrigerated wind tunnel dedicated to the study of aircraft icing. In the IRT, natural icing conditions are duplicated to test the effects of in-flight icing on actual aircraft components and on scale models of airplanes and helicopters. The IRT's ability to reproduce a natural icing cloud was significantly improved with the recent installation of a new spray bar system. It is the spray bar system that transforms the low-speed wind tunnel into an icing wind tunnel by producing microscopic droplets of water and injecting them into the wind tunnel air stream in order to accurately simulate cloud moisture.

  11. Probing Pluto's underworld: Ice temperatures from microwave radiometry decoupled from surface conditions

    NASA Astrophysics Data System (ADS)

    Leyrat, Cedric; Lorenz, Ralph D.; Le Gall, Alice

    2016-04-01

    Present models admit a wide range of 2015 surface conditions at Pluto and Charon, where the atmospheric pressure may undergo dramatic seasonal variation and for which measurements are imminent from the New Horizons mission. One anticipated observation is the microwave brightness temperature, heretofore anticipated as indicating surface conditions relevant to surface-atmosphere equilibrium. However, drawing on recent experience with Cassini observations at Iapetus and Titan, we call attention to the large electrical skin depth of outer Solar System materials such as methane, nitrogen or water ice, such that this observation may indicate temperatures averaged over depths of several or tens of meters beneath the surface. Using a seasonally-forced thermal model to determine microwave emission we predict that the southern hemisphere observations (in polar night) of New Horizons in July 2015 will suggest effective temperatures of ∼40 K, reflecting deep heat buried over the last century of summer, even if the atmospheric pressure suggests that the surface nitrogen frost point may be much lower.

  12. Evaporation Rates for Liquid Water and Ice Under Current Martian Conditions

    NASA Technical Reports Server (NTRS)

    Sears, D. W. G.; Moore, S. R.; Meier, A.; Chittenden, J.; Kareev, M.; Farmer, C. B.

    2004-01-01

    A number of studies have been concerned with the evaporation rates under martian conditions in order to place limits on the possible survival time of both liquid water and ice exposed on the surface of Mars. Such studies also aid in assessing the efficacy of an overlying layer of dust or loose regolith material in providing a barrier to free evaporation and thus prolong the lifetime of water in locations where its availability to putative living organisms would be significant. A better quantitative understanding of the effects of phase changes of water in the near surface environment would also aid the evaluation of the possible role of water in the formation of currently observed features, such as gullies in cliff walls and relatively short-term changes in the albedo of small surface areas ('dark stains'). Laboratory measurements aimed at refinement of our knowledge of these values are described here. The establishment of accurate values for evaporation rates and their dependence on the physical conditions of temperature, pressure and energy input, is an important benchmark for the further investigation of the efficacy of barriers to free evaporation in providing a prolonged period of survival of the water, particularly as a liquid.

  13. March 2003 EOS Aqua AMSR-E Arctic Sea Ice Field Campaign

    NASA Technical Reports Server (NTRS)

    Cavalieri, Donald J.; Markus, Thorsten; Maslanik, James A.; Sturm, Matthew; Lobl, Elena

    2006-01-01

    An overview of the March 2003 coordinated sea ice field campaign in the Alaskan Arctic is presented with reference to the papers in this special section. This campaign is part of the program to validate the Aqua Advanced Microwave Scanning Radiometer for Earth Observing System (AMSR-E) sea ice products. Standard AMSR-E sea ice products include sea ice concentration, sea ice temperature, and snow depth on sea ice. The validation program consists of three elements, namely: 1) satellite data comparisons; 2) coordinated satellite/aircraft surface measurements; and 3) modeling and sensitivity analyses. Landsat-7 and RADARSAT observations were used in comparative studies with the retrieved AMSR-E sea ice concentrations. The aircraft sensors provided high-resolution microwave imagery of the surface, atmospheric profiles of temperature and humidity, and digital records of sea ice conditions. When combined with in situ measurements, aircraft data were used to validate the AMSR-E sea ice temperature and snow-depth products. The modeling studies helped interpret the field-data comparisons, provided insight on the limitations of the AMSR-E sea ice algorithms, and suggested potential improvements to the AMSR-E retrieval algorithms.

  14. Climate condition in the Central Europe during the Weichselian Ice Sheet according to the Educational Global Climate Modeling Project

    NASA Astrophysics Data System (ADS)

    Szuman, Izabela; Czernecki, Bartosz

    2010-05-01

    The expansion and retreat of the ice sheet is controlled by climate changes, and from the other hand, a huge ice mass influences on the climate in the regional scale. This mechanism is commonly known as the fact but often without making reconstruction by using climatological modeling. The purpose of our study is to reconstruct the climate condition during the Weichselian Ice Sheet in the Central Europe, especially for Poland and surrounded countries. The Global Climate Model (GCM) is made for predicting climate, but simplified version can be useful for reconstructing paleoclimate. Hence, the simple initial conditions and surface data proposed by the Educational version of the GCM was applied. In our study we used a simplified version of the GCM to calculate main climate characteristics within the time limits c. 21 000 BP - 18 000 BP, which has been previously invented on Columbia University. The model is constructed on grid with a horizontal resolution 8° latitude by 10° longitude and was establish for modeling most of weather conditions based on available paleoclimate data. It is possible to estimate the probable climate condition along the southern ice sheets margin on the basis of output from the GCM and GIS modeling techniques. Above the ice mass occurs local high pressure area, which seriously interfered on atmospheric circulation. Whereas the low pressure systems in the southern part of continent may caused permanent barometric situation, which stimulates wind directions as well as the precipitable water available in the mass of air. The climate on the east-south border of ice margin was colder and drier than on the west-south region, where it was more ocean-reliable and gentle with higher temperatures. The differences in temperature between the western and eastern part of the Central Europe reached few centigrade. Against a background of the mean paleoclimatic situation in the Central Europe there is coming out a question about the particular paleoclimate

  15. In-Flight Aerodynamic Measurements of an Iced Horizontal Tailplane

    NASA Technical Reports Server (NTRS)

    Ratvasky, Thomas P.; VanZante, Judith Foss

    1999-01-01

    The effects of tailplane icing on aircraft dynamics and tailplane aerodynamics were investigated using, NASA's modified DHC-6 Twin Otter icing research aircraft. This flight program was a major element of the four-year NASA/FAA research program that also included icing wind tunnel testing, dry-air aerodynamic wind tunnel testing, and analytical code development. Flight tests were conducted to obtain aircraft dynamics and tailplane aerodynamics of the DHC-6 with four tailplane leading-edge configurations. These configurations included a clean (baseline) and three different artificial ice shapes. Quasi-steady and various dynamic flight maneuvers were performed over the full range of angles of attack and wing flap settings with each iced tailplane configuration. This paper presents results from the quasi-steady state flight conditions and describes the range of flow fields at the horizontal tailplane, the aeroperformance effect of various ice shapes on tailplane lift and elevator hinge moment, and suggests three paths that can lead toward ice-contaminated tailplane stall. It was found that wing, flap deflection was the most significant factor in driving the tailplane angle of attack toward alpha(tail stall). However, within a given flap setting, an increase in airspeed also drove the tailplane angle of attack toward alpha(tail stall). Moreover, increasing engine thrust setting also pushed the tailplane to critical performance limits, which resulted in premature tailplane stall.

  16. DRA/NASA/ONERA Collaboration on Icing Research. Part 2; Prediction of Airfoil Ice Accretion

    NASA Technical Reports Server (NTRS)

    Wright, William B.; Gent, R. W.; Guffond, Didier

    1997-01-01

    This report presents results from a joint study by DRA, NASA, and ONERA for the purpose of comparing, improving, and validating the aircraft icing computer codes developed by each agency. These codes are of three kinds: (1) water droplet trajectory prediction, (2) ice accretion modeling, and (3) transient electrothermal deicer analysis. In this joint study, the agencies compared their code predictions with each other and with experimental results. These comparison exercises were published in three technical reports, each with joint authorship. DRA published and had first authorship of Part 1 - Droplet Trajectory Calculations, NASA of Part 2 - Ice Accretion Prediction, and ONERA of Part 3 - Electrothermal Deicer Analysis. The results cover work done during the period from August 1986 to late 1991. As a result, all of the information in this report is dated. Where necessary, current information is provided to show the direction of current research. In this present report on ice accretion, each agency predicted ice shapes on two dimensional airfoils under icing conditions for which experimental ice shapes were available. In general, all three codes did a reasonable job of predicting the measured ice shapes. For any given experimental condition, one of the three codes predicted the general ice features (i.e., shape, impingement limits, mass of ice) somewhat better than did the other two. However, no single code consistently did better than the other two over the full range of conditions examined, which included rime, mixed, and glaze ice conditions. In several of the cases, DRA showed that the user's knowledge of icing can significantly improve the accuracy of the code prediction. Rime ice predictions were reasonably accurate and consistent among the codes, because droplets freeze on impact and the freezing model is simple. Glaze ice predictions were less accurate and less consistent among the codes, because the freezing model is more complex and is critically

  17. Lessons Learned from Numerical Simulations of the F-16XL Aircraft at Flight Conditions

    NASA Technical Reports Server (NTRS)

    Rizzi, Arthur; Jirasek, Adam; Lamar, John; Crippa, Simone; Badcock, Kenneth; Boelens, Oklo

    2009-01-01

    Nine groups participating in the Cranked Arrow Wing Aerodynamics Project International (CAWAPI) project have contributed steady and unsteady viscous simulations of a full-scale, semi-span model of the F-16XL aircraft. Three different categories of flight Reynolds/Mach number combinations were computed and compared with flight-test measurements for the purpose of code validation and improved understanding of the flight physics. Steady-state simulations are done with several turbulence models of different complexity with no topology information required and which overcome Boussinesq-assumption problems in vortical flows. Detached-eddy simulation (DES) and its successor delayed detached-eddy simulation (DDES) have been used to compute the time accurate flow development. Common structured and unstructured grids as well as individually-adapted unstructured grids were used. Although discrepancies are observed in the comparisons, overall reasonable agreement is demonstrated for surface pressure distribution, local skin friction and boundary velocity profiles at subsonic speeds. The physical modeling, steady or unsteady, and the grid resolution both contribute to the discrepancies observed in the comparisons with flight data, but at this time it cannot be determined how much each part contributes to the whole. Overall it can be said that the technology readiness of CFD-simulation technology for the study of vehicle performance has matured since 2001 such that it can be used today with a reasonable level of confidence for complex configurations.

  18. 14 CFR Appendix C to Part 125 - Ice Protection

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Ice Protection C Appendix C to Part 125... OR MORE; AND RULES GOVERNING PERSONS ON BOARD SUCH AIRCRAFT Pt. 125, App. C Appendix C to Part 125... conditions as described in appendix C of part 25 of this chapter. (c) Compliance with all or portions of...

  19. Ice nucleation activity of diesel soot particles at cirrus relevant temperature conditions: Effects of hydration, secondary organics coating, soot morphology, and coagulation

    NASA Astrophysics Data System (ADS)

    Kulkarni, Gourihar; China, Swarup; Liu, Shang; Nandasiri, Manjula; Sharma, Noopur; Wilson, Jacqueline; Aiken, Allison C.; Chand, Duli; Laskin, Alexander; Mazzoleni, Claudio; Pekour, Mikhail; Shilling, John; Shutthanandan, Vaithiyalingam; Zelenyuk, Alla; Zaveri, Rahul A.

    2016-04-01

    Ice formation by diesel soot particles was investigated at temperatures ranging from -40 to -50°C. Size-selected soot particles were physically and chemically aged in an environmental chamber, and their ice nucleating properties were determined using a continuous flow diffusion type ice nucleation chamber. Bare (freshly formed), hydrated, and compacted soot particles, as well as α-pinene secondary organic aerosol (SOA)-coated soot particles at high relative humidity conditions, showed ice formation activity at subsaturation conditions with respect to water but below the homogeneous freezing threshold conditions. However, SOA-coated soot particles at dry conditions were observed to freeze at homogeneous freezing threshold conditions. Overall, our results suggest that heterogeneous ice nucleation activity of freshly emitted diesel soot particles are sensitive to some of the aging processes that soot can undergo in the atmosphere.

  20. Fecal indicator bacteria persistence under natural conditions in an ice-covered river.

    PubMed

    Davenport, C V; Sparrow, E B; Gordon, R C

    1976-10-01

    Total coliform (TC), fecal coliform (FC), and fecal streptococcus (FS) survival characteristics, under natural conditions at 0 degrees C in an ice-covered river, were examined during February and March 1975. The membrane filter (MF) technique was used throughout the study, and the multiple-tube (MPN) method was used in parallel on three preselected days for comparative recovery of these bacteria. Survival was studied at seven sample stations downstream from all domestic pollution sources in a 317-km reach of the river having 7.1 days mean flow time (range of 6.0 to 9.1 days). The mean indicator bacteria densities decreased continuously at successive stations in this reach and, after adjustment for dilution, the most rapid die-off was found to occur during the first 1.9 days, followed by a slower decrease. After 7.1 days, the relative survival was TC less than FC less than FS, with 8.4%, 15.7%, and 32.8% of the initial populations remaining viable, respectively. These rates are higher than previously reported and suggest that the highest survival rates for these bacteria in receiving streams can be expected at 0 degree C under ice cover. Additionally, the FC-FS ratio was greater than 5 at all stations, indicating that this ratio may be useable for determining the source of fecal pollution in receiving streams for greater than 7 days flow time at low water temperatures. The MPN and MF methods gave comparable results for the TC and FS at all seven sample stations, with both the direct and verified MF counts within the 95% confidence limits of the respective MPNs in most samples, but generally lower than the MPN index. Although FC recovery on membrane filters was comparable results at stations near the pollution source. However, the results became more comparable with increasing flow time. The results of this study indicate that heat shock is a major factor in suppression of the FC counts on the membrane filters at 44.5 degree C. Heat shock may be minimized by extended

  1. Suspended sediment and erosion dynamics in Kugmallit Bay and Beaufort Sea during ice-free conditions

    NASA Astrophysics Data System (ADS)

    Walker, Tony R.; Grant, Jon; Cranford, Peter; Lintern, D. Gwyn; Hill, Paul; Jarvis, Peter; Barrell, Jeffrey; Nozais, Christian

    2008-12-01

    The Mackenzie River is the largest river on the North American side of the Arctic and its huge freshwater and sediment load impacts the Canadian Beaufort Shelf. Huge quantities of sediment and associated organic carbon are transported in the Mackenzie plume into the interior of the Arctic Ocean mainly during the freshet (May to September). Changing climate scenarios portend increased coastal erosion and resuspension that lead to altered river-shelf-slope particle budgets. We measured sedimentation rates, suspended particulate matter (SPM), particle size and settling rates during ice-free conditions in Kugmallit Bay (3-5 m depth). Additionally, measurements of erosion rate, critical shear stress, particle size distribution and resuspension threshold of bottom sediments were examined at four regionally contrasting sites (33-523 m depth) on the Canadian Beaufort Shelf using a new method for assessing sediment erosion. Wind induced resuspension was evidenced by a strong relationship between SPM and wind speed in Kugmallit Bay. Deployment of sediment traps showed decreasing sedimentation rates at sites along an inshore-offshore transect ranging from 5400 to 3700 g m - 2 day - 1 . Particle settling rates and size distributions measured using a Perspex settling chamber showed strong relationships between equivalent spherical diameter (ESD) and particle settling rates ( r2 = 0.91). Mean settling rates were 0.72 cm s - 1 with corresponding ESD values of 0.9 mm. Undisturbed sediment cores were exposed to shear stress in an attempt to compare differences in sediment stability across the shelf during September to October 2003. Shear was generated by vertically oscillating a perforated disc at controlled frequencies corresponding to calibrated shear velocity using a piston grid erosion device. Critical (Type I) erosion thresholds ( u*) varied between 1.1 and 1.3 cm s - 1 with no obvious differences in location. Sediments at the deepest site Amundsen Gulf displayed the highest

  2. Winter 1994 Weather and Ice Conditions for the Laurentian Great Lakes.

    NASA Astrophysics Data System (ADS)

    Assel, Raymond A.; Janowiak, John E.; Young, Sharolyn; Boyce, Daron

    1996-01-01

    The Laurentian Great Lakes developed their most extensive ice cover in over a decade during winter 1994 [December-February 1993/94 (DJF 94)]. Extensive midlake ice formation started the second half of January, about 2 weeks earlier than normal. Seasonal maximal ice extent occurred in early February, again about 2 weeks earlier than normal. Winter 1994 maximum (normal) ice coverages on the Great Lakes are Lake Superior 96% (75%), Lake Michigan 78% (45%), Lake Huron 95% (68%), Lake Erie 97% (90%), and Lake Ontario 67% (24%). Relative to the prior 31 winters (1963-93), the extent of seasonal maximal ice cover for winter 1994 for the Great Lakes taken as a unit is exceeded by only one other winter (1979); however, other winters for individual Great Lakes had similar maximal ice covers.Anomalously strong anticyclonic circulation over the central North Pacific (extending to the North Pole) and an abnormally strong polar vortex centered over northern Hudson Bay combined to produce a circulation pattern that brought frequent air masses of Arctic and polar origin to the eastern third of North America. New records were set for minimum temperatures on 19 January 1994 at many locations in the Great Lakes region. A winter severity index consisting of the average November-February air temperatures averaged over four sites on the perimeter of the Great Lakes (Duluth, Minnesota; Sault Ste. Marie, Michigan; Detroit, Michigan; and Buffalo, New York) indicates that winter 1994 was the 21st coldest since 1779. The unseasonably cold air temperatures produced much-above-normal ice cover over the Great Lakes and created problems for lake shipping. Numerous fatalities and injuries were attributed to the winter weather, which included several ice and snow storms. The much-below-normal air temperatures resulted in enhanced lake-effect snowfall along downwind lake shores, particularly during early to midwinter, prior to extensive ice formation in deeper lake areas. The low air temperatures

  3. NASA,FAA,ONERA Swept-Wing Icing and Aerodynamics: Summary of Research and Current Status

    NASA Technical Reports Server (NTRS)

    Broeren, Andy

    2015-01-01

    NASA, FAA, ONERA, and other partner organizations have embarked on a significant, collaborative research effort to address the technical challenges associated with icing on large scale, three-dimensional swept wings. These are extremely complex phenomena important to the design, certification and safe operation of small and large transport aircraft. There is increasing demand to balance trade-offs in aircraft efficiency, cost and noise that tend to compete directly with allowable performance degradations over an increasing range of icing conditions. Computational fluid dynamics codes have reached a level of maturity that they are being proposed by manufacturers for use in certification of aircraft for flight in icing. However, sufficient high-quality data to evaluate their performance on iced swept wings are not currently available in the public domain and significant knowledge gaps remain.

  4. Initial Low-Reynolds Number Iced Aerodynamic Performance for CRM Wing

    NASA Technical Reports Server (NTRS)

    Woodard, Brian; Diebold, Jeff; Broeren, Andy; Potapczuk, Mark; Lee, Sam; Bragg, Michael

    2015-01-01

    NASA, FAA, ONERA, and other partner organizations have embarked on a significant, collaborative research effort to address the technical challenges associated with icing on large scale, three-dimensional swept wings. These are extremely complex phenomena important to the design, certification and safe operation of small and large transport aircraft. There is increasing demand to balance trade-offs in aircraft efficiency, cost and noise that tend to compete directly with allowable performance degradations over an increasing range of icing conditions. Computational fluid dynamics codes have reached a level of maturity that they are being proposed by manufacturers for use in certification of aircraft for flight in icing. However, sufficient high-quality data to evaluate their performance on iced swept wings are not currently available in the public domain and significant knowledge gaps remain.

  5. Probing Pluto's Underworld : Predicted Ice Temperatures from Microwave Radiometry Decoupled from Surface Conditions

    NASA Astrophysics Data System (ADS)

    Le Gall, Alice; Lorenz, Ralph; Leyrat, Cedric

    2015-11-01

    The Pluto dwarf planet has been successfully observed in July 2015 by the New Horizons spacecraft (NASA) during a close-targeted flyby which reavealed surprising and fascinating landscapes. While data are still being downlinked on the ground, we propose to present a prediction of the observation of the Radio Science Experiment experiment (REX) that occured on July 14, 2015 and aimed at measuring the microwave brightness temperature of Pluto’s night side.Present models admit a wide range of 2015 surface conditions at Pluto and Charon, where the atmospheric pressure may undergo dramatic seasonal variation and for which measurements have been performed by the New Horizons mission. One anticipated observation is the microwave brightness temperature, heretofore anticipated as indicating surface conditions relevant to surface-atmosphere equilibrium. However, drawing on recent experience with Cassini observations at Iapetus and Titan, we call attention to the large electrical skin depth of outer solar system materials such as methane, nitrogen or water ice, such that this observation may indicate temperatures averaged over depths of several or tens of meters beneath the surface.Using a seasonally-forced thermal model to determine microwave emission we predict that the southern hemisphere observations (in the polar night in July 2015) of New Horizons should display relatively warm effective temperatures of about 40 K. This would reflect the deep heat buried over the last century of summer, even if the atmospheric pressure suggests that the surface nitrogen frost point may be much lower. We will present our predictions and discuss their impact for the interpretation of the REX measurements.

  6. Microzooplankton grazing impact in the Bering Sea during spring sea ice conditions

    NASA Astrophysics Data System (ADS)

    Sherr, Evelyn B.; Sherr, Barry F.; Ross, Celia

    2013-10-01

    Microzooplankton grazing impact on phytoplankton in the Bering Sea during spring was assessed in 2008, 2009 and 2010 using two-point dilution assays. Forty-nine experiments were completed in a region encompassing shelf to slope waters, including the 70 m line along the edge of the shelf. A variety of conditions were encountered, with a concomitant range of trophic states, from pre-bloom low chlorophyll-a (Chl-a)<3 μg l-1 during heavy ice cover to late spring open water diatom blooms with Chl-a up to 40 μg l-1. Microzooplankton biomass was dominated by large heterotrophic dinoflagellates and ciliates. Both athecate and thecate dinoflagellates, as well as some species of ciliates, fed on diatom cells and chains. Other types of protists, notably thecate amoebae and parasitoid flagellates, were also observed preying on diatoms. Total microzooplankton biomass ranged from 0.1 to 109 μg C l-1 and was positively related to Chl-a concentration. Significant rates of microzooplankton herbivory were found in 55% of dilution experiments. Maximum grazing rate was 0.49 d-1, and average grazing rate, including experiments with no significant grazing, was 0.09±0.10 d-1. Phytoplankton intrinsic growth rates varied from slightly negative growth to >0.4 d-1. Microzooplankton grazing was significant in both non-bloom and bloom conditions, averaging 46±75% of phytoplankton daily growth. Based on the amount of phytoplankton carbon consumed, we estimated potential microzooplankton community growth rates of up to 1.3 d-1. Our results confirm the importance of protist grazers in planktonic food webs of high latitude ecosystems. We also conclude that our finding of significant grazing by microzooplankton on spring blooms in the Bering Sea does not support theories about phytoplankton bloom formation based on escape from grazing, due either to predation resistance or to slow growth of herbivorous protists at cold temperature.

  7. Diatoms and biomarkers evidence for major changes in sea ice conditions prior the instrumental period in Antarctic Peninsula

    NASA Astrophysics Data System (ADS)

    Barbara, Loïc; Crosta, Xavier; Schmidt, Sabine; Massé, Guillaume

    2013-11-01

    The Antarctic Peninsula (AP) has been identified as one of the most rapidly warming region on Earth. Satellite monitoring currently allows for a detailed understanding of the relationship between sea ice extent and duration and atmospheric and oceanic circulations in this region. However, our knowledge on ocean-ice-atmosphere interactions is still relatively poor for the period extending beyond the last 30 years. Here, we describe environmental conditions in Northwestern and Northeastern Antarctic Peninsula areas over the last century using diatom census counts and diatom specific biomarkers (HBIs) in two marine sediment multicores (MTC-38C and -18A, respectively). Diatom census counts and HBIs show abrupt changes between 1935 and 1950, marked by ocean warming and sea ice retreat in both sides of the AP. Since 1950, inferred environmental conditions do not provide evidence for any trend related to the recent warming but demonstrate a pronounced variability on pluri-annual to decadal time scale. We propose that multi-decadal sea ice variations over the last century are forced by the recent warming, while the annual-to-decadal variability is mainly governed by synoptic and regional wind fields in relation with the position and intensity of the atmospheric low-pressure trough around the AP. However, the positive shift of the SAM since the last two decades cannot explain the regional trend observed in this study, probably due to the effect of local processes on the response of our biological proxies.

  8. Tomography-based characterization of ice-air interface dynamics of temperature gradient snow metamorphism under advective conditions

    NASA Astrophysics Data System (ADS)

    Ebner, Pirmin Philipp; Andreoli, Christian; Schneebeli, Martin; Steinfeld, Aldo

    2015-12-01

    Snow at or close to the surface commonly undergoes temperature gradient metamorphism under advective flow, which alters its microstructure and physical properties. A functional understanding of this process is essential for many disciplines, from modeling the effects of snow on regional and global climate to assessing avalanche formation. Time-lapse X-ray microtomography was applied to investigate the structural dynamics of temperature gradient snow metamorphism exposed to an advective airflow in controlled laboratory conditions. Experiments specifically analyzed sublimation and deposition of water vapor on the ice structure. In addition, an analysis of the ice-air interface dynamics was carried out using a macroscopic equivalent model of heat and water vapor transport through a snow layer. The results indicate that sublimation of the ice matrix dominated for flow rates < 10-6 m3 s-1 while during increased mass flow rates the water vapor deposition supplied by the advective flow counteracted sublimation. A flow rate dependence of water vapor deposition at the ice interface was observed, asymptotically approaching an average estimated maximum deposition rate on the whole sample of 1.05 · 10-4 kg m-3 s-1. The growth of microsized whisker-like crystals on larger ice crystals was detected on microscope photographs, leading to an increase of the specific surface area and thus suggest a change of the physical and optical properties of the snow. The estimated values of the curvature effect of the ice crystals and the interface kinetic coefficient are in good agreement with previously published values.

  9. 78 FR 65153 - Special Conditions: Learjet Model 45 Series Airplanes; Aircraft Electronic System Security...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-31

    ... by docket number FAA-2013-0920 using any of the following methods: Federal eRegulations Portal: Go to... unnecessary because the substance of these special conditions has been subject to the public comment process... substance of these special conditions has been subjected to the notice and comment period in several...

  10. Results of low power deicer tests on a swept inlet component in the NASA Lewis icing research tunnel

    NASA Technical Reports Server (NTRS)

    Bond, Thomas H.; Shin, Jaiwon

    1993-01-01

    Tests were conducted under a USAF/NASA Low Power Deicer program on two expulsive technologies to examine system performance on hardware representative of a modern aircraft part. The BF Goodrich Electro-Expulsive Deicing System and Pneumatic Impulse Ice Protection System were installed on a swept, compound curve, engine inlet component with varying leading edge radius, and tested through a range of icing and system operating conditions in the NASA Lewis Icing Research Tunnel. A description of the experimental procedure and results, including residual ice thickness, shed ice particle size, and changes in system energy/pressure characteristics are presented.

  11. Results of Low Power Deicer tests on a swept inlet component in the NASA Lewis Icing Research Tunnel

    NASA Technical Reports Server (NTRS)

    Bond, Thomas H.; Shin, Jaiwon

    1993-01-01

    Tests were conducted under a USAF/NASA Low Power Deicer program on two expulsive technologies to examine system performance on hardware representative of a modern aircraft part. The BF Goodrich Electro-Expulsive Deicing System and Pneumatic Impulse Ice Protection system were installed on a swept, compound curve, engine inlet component with varying leading edge radius, and tested through a range of icing and system operating conditions in the NASA Lewis Icing Research Tunnel. A description of the experimental procedure and results, including residual ice thickness, shed ice particle size, and changes in system energy/pressure characteristics are presented.

  12. Interactive, Automated Management of Icing Data

    NASA Technical Reports Server (NTRS)

    Levinson, Laurie H.

    2009-01-01

    IceVal DatAssistant is software (see figure) that provides an automated, interactive solution for the management of data from research on aircraft icing. This software consists primarily of (1) a relational database component used to store ice shape and airfoil coordinates and associated data on operational and environmental test conditions and (2) a graphically oriented database access utility, used to upload, download, process, and/or display data selected by the user. The relational database component consists of a Microsoft Access 2003 database file with nine tables containing data of different types. Included in the database are the data for all publicly releasable ice tracings with complete and verifiable test conditions from experiments conducted to date in the Glenn Research Center Icing Research Tunnel. Ice shapes from computational simulations with the correspond ing conditions performed utilizing the latest version of the LEWICE ice shape prediction code are likewise included, and are linked to the equivalent experimental runs. The database access component includes ten Microsoft Visual Basic 6.0 (VB) form modules and three VB support modules. Together, these modules enable uploading, downloading, processing, and display of all data contained in the database. This component also affords the capability to perform various database maintenance functions for example, compacting the database or creating a new, fully initialized but empty database file.

  13. Diagnostics of basal conditions - the formation of extensive zones of surface ribs in ice-sheets and streams

    NASA Astrophysics Data System (ADS)

    Hindmarsh, Richard C. A.; Sergienko, Olga V.; Creyts, Timothy T.

    2015-04-01

    Most if not all current predictions of the evolution of ice-streams to changes induced by global change assume static basal conditions. This is a result of current restrictions in the remote sensing of the ice-sheet basal physical environment, which cannot resolve the small-scale phenomena believed to control the basal traction. The search therefore is on for observable structures or features that are the result of the operation of basal processes. Any successful theory of ice-sheet basal processes would need to be able to explain such phenomena associated with or caused by special properties of the basal environment. We present one class of these phenomena, and also present tentative hypotheses as to their formation. Using recent high-resolution observations of the Antarctic and Greenland ice sheets topography, the computed driving stress and the inferred basal traction reveal broad-scale organization in 5-20 km band-like patterns in both quantities. The similarity of patterns on the Greenland and Antarctic ice sheets suggests that the flow of ice sheets is controlled by the same fundamental processes operating at their base, which control ice sheet sliding and are highly variable on relatively short spatial and temporal scales. The formation mechanism for these bands contains information about the operation of the sub-glacial system. There are three possible, non-exclusive causes of these ribs which we examine from a theoretical and evidential point-of-view (i) They are the surface response to similar bands in the basal topography, whose regularity would equally require an explanation in terms of basal processes. (ii) They are translating surface waves in the ice, supported by membrane stress gradients rather than by gradients in the basal resistance. (iii) The ribs are due to the development of a band-like structure in the basal shear stress distribution that is the result of a pattern-forming instability in sub-glacial till and water flow, perhaps related to

  14. Energy analysis of porous water ice under space-simulated conditions: results from the KOSI-8 experiment

    NASA Astrophysics Data System (ADS)

    Benkhoff, J.; Seidensticker, K. J.; Seiferlin, K.; Spohn, T.

    1995-02-01

    A sublimation experiment (KOSI-8) was performed on a pure, porous water ice sample under conditions of low pressure and temperature and insolation by an artificial sun. Temperatures within the sample, gas flux from the surface, mass loss of the sample during the experiment and the irradiation input were measured for a detailed analysis of energy flow. A main feature of the analysis was the development of a convex temperature profile along the middle axis of the sample as a consequence of heat transfer by water vapor flow. The amount of the energy transport by the water was about 40% of the total heat flux available for heating the sample. To interpret the unusually high temperatures measured a few millimeters below the surface, it is assumed that the radiative energy input penetrates about 3 mm into the sample (solid-state greenhouse effect). To trace the flow of water vapor during the experiment, the top 10 mm of the ice was enriched with 10% HDO. Ice samples for isotopic analyses were taken from the post-insolation surface and from various depths. Isotopic enrichment was observed only at the surface, corresponding to a 2.3% admixture of recondensed vapor from the initially 10-mm-thick surface layer, to a depth of 19 mm below the original surface. No isotopic enrichment could be detected below a crust that had formed, i.e. 57 mm below the original surface. During the experiment an average of about 16 mm of the ice eroded from the surface. The weight of the sample was continuously monitored and a total mass loss of 1.75 ± 0.05 kg was measured between start and end of insolation. A comparison of the power balance of a pure, porous ice sample and an ice/dust sample shows that in either case the net flux of energy available for sublimation and warming of the sample is less than 20% of the insolation. In the case of a pure ice sample, most of the irradiation is reflected due to the high albedo; in the case of an ice/dust sample, thermal reradiation of the sample is

  15. A modeling study of the aerosol effects on ice microphysics in convective cloud and precipitation development under different thermodynamic conditions

    NASA Astrophysics Data System (ADS)

    Lee, Hannah; Yum, Seong Soo; Lee, Seoung-Soo

    2014-08-01

    An improved approach for cloud droplet activation process parameterization is proposed that can utilize the empirically determined hygroscopicity information and practically limit the sizes of newly activated droplets. With the implementation of the improved approach in a cloud model, the aerosol effects on ice microphysics in convective cloud and precipitation development under different thermodynamic conditions is investigated. The model is run for four different thermodynamic soundings and three different aerosol types, maritime (M), continental (C) and polluted (P). Warm rain suppression by increased aerosol (i.e., CCN) is clearly demonstrated when weakly convective warm clouds are generated but the results are mixed when relatively stronger convective warm clouds are generated. For one of the two soundings that generate strong convective cold clouds, the accumulated precipitation amount is larger for C and P than for M, demonstrating the precipitation enhancement by increased CCN. For the maritime cloud, precipitation is initiated by the warm rain processes but ice hydrometeor particles form fast, which leads to early but weak cloud invigoration. Another stronger cloud invigoration occurs later for M but it is still weaker than that for C and P. It is the delayed accumulation of more water drops and ice particles for a burst of riming process and the latent heat release during the depositional growth of rimed ice particles that invigorate the cloud strongly for C and P. For the other sounding where freezing level is low, ice particles form fast for all three aerosol types and therefore warm rain suppression is not clearly shown. However, there still is more precipitation for C and P than for M until the accumulated precipitation amount becomes larger for M than for C near to the end of the model run. The results demonstrate that the precipitation response to aerosols indeed depends on the environmental conditions.

  16. Atmospheric synoptic conditions of snow precipitation in East Antarctica using ice core and reanalysis data

    NASA Astrophysics Data System (ADS)

    Scarchilli, Claudio; Ciardini, Virginia; Bonazza, Mattia; Frezzotti, Massimo; Stenni, Barbara

    2014-05-01

    In the framework of the International Partnerships in Ice Core Sciences (IPCS) initiatives the GV7 site (70°41' S - 158°51' E) in East Antarctica was chosen as the new drilling site for the Italian contribution to the understanding of the climatic variability in the last 2000 years (IPICS 2k Array). Water stable isotopes and snow accumulation (SMB) values from a shallow firn core, obtained at GV7 during the 2001-2002 International Trans-Antarctic Scientific Expedition (ITASE) traverse, are analyzed and compared with different meteorological model output in order to characterize the atmospheric synoptic conditions driving precipitation events at the site. On annual basis, ECMWF +24h forecasted snowfalls (SF) seem to well reproduce GV7 SMB values trend for the period from 1980 to 2005. Calculated air mass back-trajectories show that Eastern Indian - Western Pacific oceans represent the main moisture path toward the site during autumn - winter season. Analysis of the ECMWF 500 hPa Geopotential height field (GP500) anomalies shows that atmospheric blocking events developing between 130° E and 150° W at high latitudes drive the GV7 SMB by blocking zonal flow and conveying warm and moist deep air masses from ocean into the continental interior. On inter-annual basis, The SF variability over GV7 region follows the temporal oscillation of the third CEOF mode (CEOF3 10% of the total explained variance) of a combined complex empirical orthogonal function (CEOF) performed over GP500 and SF field. The CEOF3 highlights an oscillating feature, with wavenumber 2, in GP500 field over the Western Pacific-Eastern Indian Oceans and propagating westward. The pattern is deeply correlated with the Indian Dipole Oscillation and ENSO and their associated quasi-stationary Rossby waves propagating from the lower toward the higher latitudes.

  17. An Improved Gaussian Mixture Model for Damage Propagation Monitoring of an Aircraft Wing Spar under Changing Structural Boundary Conditions.

    PubMed

    Qiu, Lei; Yuan, Shenfang; Mei, Hanfei; Fang, Fang

    2016-02-26

    Structural Health Monitoring (SHM) technology is considered to be a key technology to reduce the maintenance cost and meanwhile ensure the operational safety of aircraft structures. It has gradually developed from theoretic and fundamental research to real-world engineering applications in recent decades. The problem of reliable damage monitoring under time-varying conditions is a main issue for the aerospace engineering applications of SHM technology. Among the existing SHM methods, Guided Wave (GW) and piezoelectric sensor-based SHM technique is a promising method due to its high damage sensitivity and long monitoring range. Nevertheless the reliability problem should be addressed. Several methods including environmental parameter compensation, baseline signal dependency reduction and data normalization, have been well studied but limitations remain. This paper proposes a damage propagation monitoring method based on an improved Gaussian Mixture Model (GMM). It can be used on-line without any structural mechanical model and a priori knowledge of damage and time-varying conditions. With this method, a baseline GMM is constructed first based on the GW features obtained under time-varying conditions when the structure under monitoring is in the healthy state. When a new GW feature is obtained during the on-line damage monitoring process, the GMM can be updated by an adaptive migration mechanism including dynamic learning and Gaussian components split-merge. The mixture probability distribution structure of the GMM and the number of Gaussian components can be optimized adaptively. Then an on-line GMM can be obtained. Finally, a best match based Kullback-Leibler (KL) divergence is studied to measure the migration degree between the baseline GMM and the on-line GMM to reveal the weak cumulative changes of the damage propagation mixed in the time-varying influence. A wing spar of an aircraft is used to validate the proposed method. The results indicate that the crack

  18. An Improved Gaussian Mixture Model for Damage Propagation Monitoring of an Aircraft Wing Spar under Changing Structural Boundary Conditions

    PubMed Central

    Qiu, Lei; Yuan, Shenfang; Mei, Hanfei; Fang, Fang

    2016-01-01

    Structural Health Monitoring (SHM) technology is considered to be a key technology to reduce the maintenance cost and meanwhile ensure the operational safety of aircraft structures. It has gradually developed from theoretic and fundamental research to real-world engineering applications in recent decades. The problem of reliable damage monitoring under time-varying conditions is a main issue for the aerospace engineering applications of SHM technology. Among the existing SHM methods, Guided Wave (GW) and piezoelectric sensor-based SHM technique is a promising method due to its high damage sensitivity and long monitoring range. Nevertheless the reliability problem should be addressed. Several methods including environmental parameter compensation, baseline signal dependency reduction and data normalization, have been well studied but limitations remain. This paper proposes a damage propagation monitoring method based on an improved Gaussian Mixture Model (GMM). It can be used on-line without any structural mechanical model and a priori knowledge of damage and time-varying conditions. With this method, a baseline GMM is constructed first based on the GW features obtained under time-varying conditions when the structure under monitoring is in the healthy state. When a new GW feature is obtained during the on-line damage monitoring process, the GMM can be updated by an adaptive migration mechanism including dynamic learning and Gaussian components split-merge. The mixture probability distribution structure of the GMM and the number of Gaussian components can be optimized adaptively. Then an on-line GMM can be obtained. Finally, a best match based Kullback-Leibler (KL) divergence is studied to measure the migration degree between the baseline GMM and the on-line GMM to reveal the weak cumulative changes of the damage propagation mixed in the time-varying influence. A wing spar of an aircraft is used to validate the proposed method. The results indicate that the crack

  19. An Improved Gaussian Mixture Model for Damage Propagation Monitoring of an Aircraft Wing Spar under Changing Structural Boundary Conditions.

    PubMed

    Qiu, Lei; Yuan, Shenfang; Mei, Hanfei; Fang, Fang

    2016-01-01

    Structural Health Monitoring (SHM) technology is considered to be a key technology to reduce the maintenance cost and meanwhile ensure the operational safety of aircraft structures. It has gradually developed from theoretic and fundamental research to real-world engineering applications in recent decades. The problem of reliable damage monitoring under time-varying conditions is a main issue for the aerospace engineering applications of SHM technology. Among the existing SHM methods, Guided Wave (GW) and piezoelectric sensor-based SHM technique is a promising method due to its high damage sensitivity and long monitoring range. Nevertheless the reliability problem should be addressed. Several methods including environmental parameter compensation, baseline signal dependency reduction and data normalization, have been well studied but limitations remain. This paper proposes a damage propagation monitoring method based on an improved Gaussian Mixture Model (GMM). It can be used on-line without any structural mechanical model and a priori knowledge of damage and time-varying conditions. With this method, a baseline GMM is constructed first based on the GW features obtained under time-varying conditions when the structure under monitoring is in the healthy state. When a new GW feature is obtained during the on-line damage monitoring process, the GMM can be updated by an adaptive migration mechanism including dynamic learning and Gaussian components split-merge. The mixture probability distribution structure of the GMM and the number of Gaussian components can be optimized adaptively. Then an on-line GMM can be obtained. Finally, a best match based Kullback-Leibler (KL) divergence is studied to measure the migration degree between the baseline GMM and the on-line GMM to reveal the weak cumulative changes of the damage propagation mixed in the time-varying influence. A wing spar of an aircraft is used to validate the proposed method. The results indicate that the crack

  20. Radiocarbon ages of terrestrial gastropods extend duration of ice-free conditions at the Two Creeks forest bed, Wisconsin, USA

    USGS Publications Warehouse

    Rech, Jason A.; Nekola, Jeffrey C.; Pigati, Jeffrey S.

    2012-01-01

    Analysis of terrestrial gastropods that underlie the late Pleistocene Two Creeks forest bed (~ 13,800–13,500 cal yr BP) in eastern Wisconsin, USA provides evidence for a mixed tundra-taiga environment prior to formation of the taiga forest bed. Ten new AMS 14C analyses on terrestrial gastropod shells indicate the mixed tundra-taiga environment persisted from ~ 14,500 to 13,900 cal yr BP. The Twocreekan climatic substage, representing ice-free conditions on the shore of Lake Michigan, therefore began near the onset of peak warming conditions during the Bølling–Allerød interstadial and lasted ~ 1000 yr, nearly 600 yr longer than previously thought. These results provide important data for understanding the response of continental ice sheets to global climate forcing and demonstrate the potential of using terrestrial gastropod fossils for both environmental reconstruction and age control in late Quaternary sediments.

  1. Mood after various brief exercise and sport modes: aerobics, hip-hop dancing, ice skating, and body conditioning.

    PubMed

    Kim, Sungwoon; Kim, Jingu

    2007-06-01

    To investigate the potential psychological benefits of brief exercise and sport activities on positive mood alterations, 45 Korean high school and 232 undergraduate students enrolled in physical education and stress management classes voluntarily participated and were randomly assigned to one of four activities: aerobic exercise, body conditioning, hip-hop dancing, and ice skating. Mood changes from before to after exercise (2 pm to 3 pm) were measured based on a Korean translation of the Subjective Exercise Experiences Scale. The findings suggested that the aerobics and hip-hop dancing groups rated positive well-being higher than the body conditioning and ice skating groups. Immediately after exercise, psychological distress was rated lower in the aerobics and hip-hop dancing groups, as was fatigue.

  2. Implications of Contingency Planning Support for Weather and Icing Information

    NASA Technical Reports Server (NTRS)

    Vigeant-Langlois, Laurence; Hansman, R. John, Jr.

    2003-01-01

    A human-centered systems analysis was applied to the adverse aircraft weather encounter problem in order to identify desirable functions of weather and icing information. The importance of contingency planning was identified as emerging from a system safety design methodology as well as from results of other aviation decision-making studies. The relationship between contingency planning support and information on regions clear of adverse weather was investigated in a scenario- based analysis. A rapid prototype example of the key elements in the depiction of icing conditions was developed in a case study, and the implications for the components of the icing information system were articulated.

  3. Subglacial conditions and Scandinavian Ice Sheet dynamics at the coarse-grained substratum of the fore-mountain area of southern Poland

    NASA Astrophysics Data System (ADS)

    Salamon, Tomasz

    2016-11-01

    The fore-mountain areas of southern Poland are locally composed of the coarse-grained sediments of alluvial fans, which created unusual conditions under the advancing Scandinavian Ice Sheet during the Elsterian glaciation. This highly permeable substratum potentially enabled rapid outflow of meltwater from the ice sheet base, thereby reducing the water pressure and strongly influencing the ice sheet dynamics. The subglacial conditions and the relationship between the ice sheet behaviour and its coarse-grained substratum were studied at the foreland of the western Carpathian Mountains. The sedimentological and structural analysis of the till and related sediments that were deposited above the alluvial gravel of the fore-mountain fans are presented. The study indicates that despite the high permeability of the coarse-grained substratum, it did not slow the ice sheet movement. Conversely, the ice sheet moved mainly due to basal slip and locally shallow deformations. This was a consequence of very high basal water pressure, which resulted largely from the presence of permafrost that restricted subglacial groundwater outflow. In addition, the ice sheet substratum was inclined opposite to the direction of its movement, increasing the pressure of the subglacial water. Numerous subhorizontal sandy laminae within the till indicate that the meltwater from the ice sheet base was drained by a water film along the ice/bed interface. The water escape structures within the till and subtill sediments indicate the occasional instability of the ice sheet hydrological system and suggest that the meltwater was periodically stored in the ice sheet base. Temporal changes occurring in the ice sheet hydrological system might indicate variations in the ice sheet behaviour; i.e. phases of relatively fast ice flow and phases of ice stagnation. The latter were probably correlated with the freezing of the ice margin to its base. The study shows how the coarse-grained substratum could

  4. Influence of wet conditions on snow temperature diurnal variations: An East Antarctic sea-ice case study

    NASA Astrophysics Data System (ADS)

    Lecomte, O.; Toyota, T.

    2016-09-01

    A one-dimensional snow-sea-ice model is used to simulate the evolution of temperature profiles in dry and wet snow over a diurnal cycle, at locations where associated observations collected during the Sea Ice Physics and Ecosystem eXperiment (SIPEX-II) are available. The model is used at two sites, corresponding to two of the field campaign's sea-ice stations (2 and 6), and under two configurations: dry and wet snow conditions. In the wet snow model setups, liquid water may refreeze internally into the snow. At station 6, this releases latent heat to the snow and results in temperature changes at the base of the snow pack of a magnitude comparing to the model-observation difference (1 - 2 ° C). As the temperature gradient across the snow is in turn weakened, the associated conductive heat flux through snow decreases. At station 2, internal refreezing also occurs but colder air temperatures and the competing process of strengthened heat conduction in snow concurrent to snow densification maintain a steady temperature profile. However, both situations share a common feature and show that the conductive heat flux through the snow may significantly be affected (by 10-20% in our simulations) as a result of the liquid water refreezing in snow, either through thermal conductivity enhancement or direct temperature gradient alteration. This ultimately gives motivation for further investigating the impacts of these processes on the sea-ice mass balance in the framework of global scale model simulations.

  5. An overview of shed ice impact in the NASA Lewis Icing Research Tunnel

    NASA Technical Reports Server (NTRS)

    Bond, Thomas H.; Britton, Randall K.

    1993-01-01

    One of the areas of active research in commercial and military rotorcraft is directed toward developing the capability of sustained flight in icing conditions. The emphasis to date has been on the accretion and subsequent shedding of ice in an icing environment, where the shedding may be natural or induced. Historically, shed-ice particles have been a problem for aircraft, particularly rotorcraft. Because of the high particle velocities involved, damage to a fuselage or other airframe component from a shed-ice impact can be significant. Design rules for damage tolerance from shed-ice impact are not well developed because of a lack of experimental data. Thus, NASA Lewis (LeRC) has begun an effort to develop a database of impact force and energy resulting from shed ice. This effort consisted of a test of NASA LeRC's Model Rotor Test Rig (MRTR) in the Icing Research Tunnel (IRT). Both natural shedding and forced shedding were investigated. Forced shedding was achieved by fitting the rotor blades with Small Tube Pneumatic (STP) deicer boots manufactured by BF Goodrich. A detailed description of the test is given as well as the design of a new impact sensor which measures the force-time history of an impacting ice fragment. A brief discussion of the procedure to infer impact energy from a force-time trace are required for the impact-energy calculations. Recommendations and future plans for this research area are also provided.

  6. An overview of shed ice impact studies in the NASA Lewis Icing Research Tunnel

    NASA Technical Reports Server (NTRS)

    Britton, Randall K.; Bond, Thomas H.

    1993-01-01

    One of the areas of active research in commercial and military rotorcraft is directed toward developing the capability of sustained flight in icing conditions. The emphasis to date has been on the accretion and subsequent shedding of ice in an icing environment, where the shedding may be natural or induced. Historically, shed-ice particles have been a problem for aircraft, particularly rotorcraft. Because of the high particle velocities involved, damage to a fuselage or other airframe component from a shed-ice impact can be significant. Design rules for damage tolerance from shed-ice impact are not well developed because of a lack of experimental data. Thus, NASA Lewis (LeRC) has begun an effort to develop a database of impact force and energy resulting from shed ice. This effort consisted of a test of NASA LeRC's Model Rotor Test Rig (MRTR) in the Icing Research Tunnel (IRT). Both natural shedding and forced shedding were investigated. Forced shedding was achieved by fitting the rotor blades with Small Tube Pneumatic (STP) deicer boots manufactured by BF Goodrich. A detailed description of the test is given as well as the design of a new impact sensor which measures the force-time history of an impacting ice fragment. A brief discussion of the procedure to infer impact energy from a force-time trace are required for the impact-energy calculations. Recommendations and future plans for this research area are also provided.

  7. Comparison of In-Situ, Model and Ground Based In-Flight Icing Severity

    NASA Technical Reports Server (NTRS)

    Johnston, Christopher J.; Serke, David J.; Adriaansen, Daniel R.; Reehorst, Andrew L.; Politovich, Marica K.; Wolff, Cory A.; McDonough, Frank

    2011-01-01

    As an aircraft flies through supercooled liquid water, the liquid freezes instantaneously to the airframe thus altering its lift, drag, and weight characteristics. In-flight icing is a contributing factor to many aviation accidents, and the reliable detection of this hazard is a fundamental concern to aviation safety. The scientific community has recently developed products to provide in-flight icing warnings. NASA's Icing Remote Sensing System (NIRSS) deploys a vertically--pointing Ka--band radar, a laser ceilometer, and a profiling multi-channel microwave radiometer for the diagnosis of terminal area in-flight icing hazards with high spatial and temporal resolution. NCAR s Current Icing Product (CIP) combines several meteorological inputs to produce a gridded, three-dimensional depiction of icing severity on an hourly basis. Pilot reports are the best and only source of information on in-situ icing conditions encountered by an aircraft. The goal of this analysis was to ascertain how the testbed NIRSS icing severity product and the operational CIP severity product compare to pilot reports of icing severity, and how NIRSS and CIP compare to each other. This study revealed that the icing severity product from the ground-based NASA testbed system compared very favorably with the operational model-based product and pilot reported in-situ icing.

  8. Ice Accretion with Varying Surface Tension

    NASA Technical Reports Server (NTRS)

    Bilanin, Alan J.; Anderson, David N.

    1995-01-01

    During an icing encounter of an aircraft in flight, super-cooled water droplets impinging on an airfoil may splash before freezing. This paper reports tests performed to determine if this effect is significant and uses the results to develop an improved scaling method for use in icing test facilities. Simple laboratory tests showed that drops splash on impact at the Reynolds and Weber numbers typical of icing encounters. Further confirmation of droplet splash came from icing tests performed in the NaSA Lewis Icing Research Tunnel (IRT) with a surfactant added to the spray water to reduce the surface tension. The resulting ice shapes were significantly different from those formed when no surfactant was added to the water. These results suggested that the droplet Weber number must be kept constant to properly scale icing test conditions. Finally, the paper presents a Weber-number-based scaling method and reports results from scaling tests in the IRT in which model size was reduced up to a factor of 3. Scale and reference ice shapes are shown which confirm the effectiveness of this new scaling method.

  9. 76 FR 65105 - Special Conditions: Gulfstream Aerospace Corporation, Model GIV-X Airplane; Isolation or Aircraft...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-20

    ... necessary to establish a level of safety equivalent to that established by the existing airworthiness... the Federal Register published on April 11, 2000 (65 FR 19477-19478), as well as at http://DocketsInfo..., exemptions, and equivalent safety findings that are not relevant to these special conditions. If...

  10. Estimating Chlorophyll Conditions in Southern New England Coastal Waters from Hyperspectral Aircraft Remote Sensing

    EPA Science Inventory

    Chlorophyll a (chl a) is commonly measured in water quality monitoring programs for coastal and freshwater systems. The concentration of chl a, when evaluated with other condition indicators such as water clarity and dissolved oxygen concentrations, provides information on the en...

  11. 78 FR 28719 - Special Conditions: Cessna Aircraft Company, Model J182T; Diesel Cycle Engine Installation

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-16

    ... be found in the Federal Register published on April 11, 2000 (65 FR 19477-19478), as well as at http... vibration characteristics, both normal and with an inoperative cylinder, anticipated use of an electronic... vibration levels under both normal operating conditions and when one cylinder is inoperative. The...

  12. Borehole radar investigations for locating ice ring formed by cryogenic condition in an underground cavern

    NASA Astrophysics Data System (ADS)

    Kim, Jung-Ho; Park, Sam-Gyu; Yi, Myeong-Jong; Son, Jeong-Sul; Cho, Seong-Jun

    2007-07-01

    A small underground pilot plant was constructed and operated at Korea Institute of Geoscience and Mineral Resources for investigating the feasibility of a new concept of storing liquefied natural gas (LNG) in a lined hard rock cavern. In the real operation of the pilot plant, liquid nitrogen (LN2) was stored instead of LNG for safety purpose. A drainage system controls the development of an impervious ring of ice formed due to storage of LN2 in extremely low temperature. The ice ring formed around the storage cavern is very important because this can act as the final barrier to secure the LNG storage. We carried out borehole radar surveys to study the applicability of the borehole radar reflection method to locating the ice ring formation. Prior to conducting the fieldwork, we performed numerical experiments of borehole radar reflection survey; through the analysis of the numerical modeled data we obtained the most appropriate interpretation strategies for locating the ice rings. Before and after storing the LN2 in the underground cavern, we conducted borehole radar reflection and crosshole level scanning surveys. The data obtained at the two stages of the surveys were compared in order to identify changes occurring in basement rock after storing the LN2. The interpretation of the borehole radar data clearly showed that the ice rings only developed under and in front of the LNG storage cavern of the pilot plant, but not over it. Through the numerical modeling experiments and field monitoring exercises, we were able to know that borehole radar reflection technique is an effective method for locating ice rings formed in basement rock for storing material of extremely low temperature in an underground cavern.

  13. A new coupled ice sheet-climate model: description and sensitivity to model physics under Eemian, Last Glacial Maximum, late Holocene and modern climate conditions

    NASA Astrophysics Data System (ADS)

    Fyke, J. G.; Weaver, A. J.; Pollard, D.; Eby, M.; Carter, L.; Mackintosh, A.

    2010-08-01

    The need to better understand long-term climate/ice sheet feedback loops is motivating efforts to couple ice sheet models into Earth System models which are capable of long-timescale simulations. In this paper we describe a coupled model, that consists of the University of Victoria Earth System Climate Model (UVic ESCM) and the Pennsylvania State University Ice model (PSUI). The climate model generates a surface mass balance (SMB) field via a sub-gridded surface energy/moisture balance model that resolves narrow ice sheet ablation zones. The ice model returns revised elevation, surface albedo and ice area fields, plus coastal fluxes of heat and moisture. An arbitrary number of ice sheets can be simulated, each on their own high-resolution grid and each capable of synchronous or asynchronous coupling with the overlying climate model. The model is designed to conserve global heat and moisture. In the process of improving model performance we developed a procedure to account for modelled surface air temperature (SAT) biases within the energy/moisture balance surface model and improved the UVic ESCM snow surface scheme through addition of variable albedos and refreezing over the ice sheet. A number of simulations for late Holocene, Last Glacial Maximum (LGM), and Eemian climate boundary conditions were carried out to explore the sensitivity of the coupled model and identify model configurations that best represented these climate states. The modelled SAT bias was found to play a significant role in long-term ice sheet evolution, as was the effect of refreezing meltwater and surface albedo. The bias-corrected model was able to reasonably capture important aspects of the Antarctic and Greenland ice sheets, including modern SMB and ice distribution. The simulated northern Greenland ice sheet was found to be prone to ice margin retreat at radiative forcings corresponding closely to those of the Eemian or the present-day.

  14. A new coupled ice sheet/climate model: description and sensitivity to model physics under Eemian, Last Glacial Maximum, late Holocene and modern climate conditions

    NASA Astrophysics Data System (ADS)

    Fyke, J. G.; Weaver, A. J.; Pollard, D.; Eby, M.; Carter, L.; Mackintosh, A.

    2011-03-01

    The need to better understand long-term climate/ice sheet feedback loops is motivating efforts to couple ice sheet models into Earth System models which are capable of long-timescale simulations. In this paper we describe a coupled model that consists of the University of Victoria Earth System Climate Model (UVic ESCM) and the Pennsylvania State University Ice model (PSUI). The climate model generates a surface mass balance (SMB) field via a sub-gridded surface energy/moisture balance model that resolves narrow ice sheet ablation zones. The ice model returns revised elevation, surface albedo and ice area fields, plus coastal fluxes of heat and moisture. An arbitrary number of ice sheets can be simulated, each on their own high-resolution grid and each capable of synchronous or asynchronous coupling with the overlying climate model. The model is designed to conserve global heat and moisture. In the process of improving model performance we developed a procedure to account for modelled surface air temperature (SAT) biases within the energy/moisture balance surface model and improved the UVic ESCM snow surface scheme through addition of variable albedos and refreezing over the ice sheet. A number of simulations for late Holocene, Last Glacial Maximum (LGM), and Eemian climate boundary conditions were carried out to explore the sensitivity of the coupled model and identify model configurations that best represented these climate states. The modelled SAT bias was found to play a significant role in long-term ice sheet evolution, as was the effect of refreezing meltwater and surface albedo. The bias-corrected model was able to reasonably capture important aspects of the Antarctic and Greenland ice sheets, including modern SMB and ice distribution. The simulated northern Greenland ice sheet was found to be prone to ice margin retreat at radiative forcings corresponding closely to those of the Eemian or the present-day.

  15. Effective Sensor Selection and Data Anomaly Detection for Condition Monitoring of Aircraft Engines

    PubMed Central

    Liu, Liansheng; Liu, Datong; Zhang, Yujie; Peng, Yu

    2016-01-01

    In a complex system, condition monitoring (CM) can collect the system working status. The condition is mainly sensed by the pre-deployed sensors in/on the system. Most existing works study how to utilize the condition information to predict the upcoming anomalies, faults, or failures. There is also some research which focuses on the faults or anomalies of the sensing element (i.e., sensor) to enhance the system reliability. However, existing approaches ignore the correlation between sensor selecting strategy and data anomaly detection, which can also improve the system reliability. To address this issue, we study a new scheme which includes sensor selection strategy and data anomaly detection by utilizing information theory and Gaussian Process Regression (GPR). The sensors that are more appropriate for the system CM are first selected. Then, mutual information is utilized to weight the correlation among different sensors. The anomaly detection is carried out by using the correlation of sensor data. The sensor data sets that are utilized to carry out the evaluation are provided by National Aeronautics and Space Administration (NASA) Ames Research Center and have been used as Prognostics and Health Management (PHM) challenge data in 2008. By comparing the two different sensor selection strategies, the effectiveness of selection method on data anomaly detection is proved. PMID:27136561

  16. Effective Sensor Selection and Data Anomaly Detection for Condition Monitoring of Aircraft Engines.

    PubMed

    Liu, Liansheng; Liu, Datong; Zhang, Yujie; Peng, Yu

    2016-04-29

    In a complex system, condition monitoring (CM) can collect the system working status. The condition is mainly sensed by the pre-deployed sensors in/on the system. Most existing works study how to utilize the condition information to predict the upcoming anomalies, faults, or failures. There is also some research which focuses on the faults or anomalies of the sensing element (i.e., sensor) to enhance the system reliability. However, existing approaches ignore the correlation between sensor selecting strategy and data anomaly detection, which can also improve the system reliability. To address this issue, we study a new scheme which includes sensor selection strategy and data anomaly detection by utilizing information theory and Gaussian Process Regression (GPR). The sensors that are more appropriate for the system CM are first selected. Then, mutual information is utilized to weight the correlation among different sensors. The anomaly detection is carried out by using the correlation of sensor data. The sensor data sets that are utilized to carry out the evaluation are provided by National Aeronautics and Space Administration (NASA) Ames Research Center and have been used as Prognostics and Health Management (PHM) challenge data in 2008. By comparing the two different sensor selection strategies, the effectiveness of selection method on data anomaly detection is proved.

  17. Effective Sensor Selection and Data Anomaly Detection for Condition Monitoring of Aircraft Engines.

    PubMed

    Liu, Liansheng; Liu, Datong; Zhang, Yujie; Peng, Yu

    2016-01-01

    In a complex system, condition monitoring (CM) can collect the system working status. The condition is mainly sensed by the pre-deployed sensors in/on the system. Most existing works study how to utilize the condition information to predict the upcoming anomalies, faults, or failures. There is also some research which focuses on the faults or anomalies of the sensing element (i.e., sensor) to enhance the system reliability. However, existing approaches ignore the correlation between sensor selecting strategy and data anomaly detection, which can also improve the system reliability. To address this issue, we study a new scheme which includes sensor selection strategy and data anomaly detection by utilizing information theory and Gaussian Process Regression (GPR). The sensors that are more appropriate for the system CM are first selected. Then, mutual information is utilized to weight the correlation among different sensors. The anomaly detection is carried out by using the correlation of sensor data. The sensor data sets that are utilized to carry out the evaluation are provided by National Aeronautics and Space Administration (NASA) Ames Research Center and have been used as Prognostics and Health Management (PHM) challenge data in 2008. By comparing the two different sensor selection strategies, the effectiveness of selection method on data anomaly detection is proved. PMID:27136561

  18. Lobster Tail Ice Formation on Aerosurface

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Glace Ice formation commonly refered to as 'Lobster Tail' by scientists and engineers, is caused to form on the leading edge of a aircraft tail section in the icing research tunnel at the NASA Glenn Research Center, Cleveland, Ohio.

  19. Predicting Accumulations of Ice on Aerodynamic Surfaces

    NASA Technical Reports Server (NTRS)

    Bidwell, Colin; Potapczuk, Mark; Addy, Gene; Wright, William

    2003-01-01

    LEWICE is a computer program that predicts the accumulation of ice on two-dimensional aerodynamic surfaces under conditions representative of the flight of an aircraft through an icing cloud. The software first calculates the airflow surrounding the body of interest, then uses the airflow to compute the trajectories of water droplets that impinge on the surface of the body. The droplet trajectories are also used to compute impingement limits and local collection efficiencies, which are used in subsequent ice-growth calculations and are also useful for designing systems to protect against icing. Next, the software predicts the shape of accumulating ice by modeling transfers of mass and energy in small control volumes. The foregoing computations are repeated over several computational time steps until the total icing exposure time is reached. Results of computations by LEWICE have been compared with an extensive database of measured ice shapes obtained from experiments, and have been shown to closely approximate those shapes under most conditions of interest to the aviation community.

  20. Sea Ice

    NASA Technical Reports Server (NTRS)

    Perovich, D.; Gerland, S.; Hendricks, S.; Meier, Walter N.; Nicolaus, M.; Richter-Menge, J.; Tschudi, M.

    2013-01-01

    During 2013, Arctic sea ice extent remained well below normal, but the September 2013 minimum extent was substantially higher than the record-breaking minimum in 2012. Nonetheless, the minimum was still much lower than normal and the long-term trend Arctic September extent is -13.7 per decade relative to the 1981-2010 average. The less extreme conditions this year compared to 2012 were due to cooler temperatures and wind patterns that favored retention of ice through the summer. Sea ice thickness and volume remained near record-low levels, though indications are of slightly thicker ice compared to the record low of 2012.

  1. The Potential of Using Landsat 7 Data for the Classification of Sea Ice Surface Conditions During Summer

    NASA Technical Reports Server (NTRS)

    Markus, Thorsten; Cavalieri, Donald J.; Ivanoff, Alvaro; Koblinsky, Chester J. (Technical Monitor)

    2001-01-01

    During spring and summer, the Surface of the Arctic sea ice cover undergoes rapid changes that greatly affect the surface albedo and significantly impact the further decay of the sea ice. These changes are primarily the development of a wet snow cover and the development of melt ponds. As melt pond diameters generally do not exceed a couple of meters, the spatial resolutions of sensors like AVHRR and MODIS are too coarse for their identification. Landsat 7, on the other hand, has a spatial resolution of 30 m (15 m for the pan-chromatic band). The different wavelengths (bands) from blue to near-infrared offer the potential to distinguish among different surface conditions. Landsat 7 data for the Baffin Bay region for June 2000 have been analyzed. The analysis shows that different surface conditions, such as wet snow and meltponded areas, have different signatures in the individual Landsat bands. Consistent with in-situ albedo measurements, melt ponds show up as blueish whereas dry and wet ice have a white to gray appearance in the Landsat true-color image. These spectral differences enable the distinction of melt ponds. The melt pond fraction for the scene studied in this paper was 37%.

  2. Ice Accretions and Full-Scale Iced Aerodynamic Performance Data for a Two-Dimensional NACA 23012 Airfoil

    NASA Technical Reports Server (NTRS)

    Addy, Harold E., Jr.; Broeren, Andy P.; Potapczuk, Mark G.; Lee, Sam; Guffond, Didier; Montreuil, Emmanuel; Moens, Frederic

    2016-01-01

    This report documents the data collected during the large wind tunnel campaigns conducted as part of the SUNSET project (StUdies oN Scaling EffecTs due to ice) also known as the Ice-Accretion Aerodynamics Simulation study: a joint effort by NASA, the Office National d'Etudes et Recherches Aérospatiales (ONERA), and the University of Illinois. These data form a benchmark database of full-scale ice accretions and corresponding ice-contaminated aerodynamic performance data for a two-dimensional (2D) NACA 23012 airfoil. The wider research effort also included an analysis of ice-contaminated aerodynamics that categorized ice accretions by aerodynamic effects and an investigation of subscale, low- Reynolds-number ice-contaminated aerodynamics for the NACA 23012 airfoil. The low-Reynolds-number investigation included an analysis of the geometric fidelity needed to reliably assess aerodynamic effects of airfoil icing using artificial ice shapes. Included herein are records of the ice accreted during campaigns in NASA Glenn Research Center's Icing Research Tunnel (IRT). Two different 2D NACA 23012 airfoil models were used during these campaigns; an 18-in. (45.7-cm) chord (subscale) model and a 72-in. (182.9-cm) chord (full-scale) model. The aircraft icing conditions used during these campaigns were selected from the Federal Aviation Administration's (FAA's) Code of Federal Regulations (CFR) Part 25 Appendix C icing envelopes. The records include the test conditions, photographs of the ice accreted, tracings of the ice, and ice depth measurements. Model coordinates and pressure tap locations are also presented. Also included herein are the data recorded during a wind tunnel campaign conducted in the F1 Subsonic Pressurized Wind Tunnel of ONERA. The F1 tunnel is a pressured, high- Reynolds-number facility that could accommodate the full-scale (72-in. (182.9-cm) chord) 2D NACA 23012 model. Molds were made of the ice accreted during selected test runs of the full-scale model

  3. Aerodynamic Classification of Swept-Wing Ice Accretion

    NASA Technical Reports Server (NTRS)

    Diebold, Jeff M.; Broeren, Andy P.; Bragg, Michael B.

    2013-01-01

    The continued design, certification and safe operation of swept-wing airplanes in icing conditions rely on the advancement of computational and experimental simulation methods for higher fidelity results over an increasing range of aircraft configurations and performance, and icing conditions. The current state-of-the-art in icing aerodynamics is mainly built upon a comprehensive understanding of two-dimensional geometries that does not currently exist for fundamentally three-dimensional geometries such as swept wings. The purpose of this report is to describe what is known of iced-swept-wing aerodynamics and to identify the type of research that is required to improve the current understanding. Following the method used in a previous review of iced-airfoil aerodynamics, this report proposes a classification of swept-wing ice accretion into four groups based upon unique flowfield attributes. These four groups are: ice roughness, horn ice, streamwise ice and spanwise-ridge ice. In the case of horn ice it is shown that a further subclassification of nominally 3D or highly 3D horn ice may be necessary. For all of the proposed ice-shape classifications, relatively little is known about the three-dimensional flowfield and even less about the effect of Reynolds number and Mach number on these flowfields. The classifications and supporting data presented in this report can serve as a starting point as new research explores swept-wing aerodynamics with ice shapes. As further results are available, it is expected that these classifications will need to be updated and revised.

  4. Aerodynamic Classification of Swept-Wing Ice Accretion

    NASA Technical Reports Server (NTRS)

    Diebold, Jeff M.; Broeren, Andy P.; Bragg, Michael B.

    2013-01-01

    The continued design, certification and safe operation of swept-wing airplanes in icing conditions rely on the advancement of computational and experimental simulation methods for higher fidelity results over an increasing range of aircraft configurations and performance, and icing conditions. The current stateof- the-art in icing aerodynamics is mainly built upon a comprehensive understanding of two-dimensional geometries that does not currently exist for fundamentally three-dimensional geometries such as swept wings. The purpose of this report is to describe what is known of iced-swept-wing aerodynamics and to identify the type of research that is required to improve the current understanding. Following the method used in a previous review of iced-airfoil aerodynamics, this report proposes a classification of swept-wing ice accretion into four groups based upon unique flowfield attributes. These four groups are: ice roughness, horn ice, streamwise ice and spanwise-ridge ice. In the case of horn ice it is shown that a further subclassification of "nominally 3D" or "highly 3D" horn ice may be necessary. For all of the proposed ice-shape classifications, relatively little is known about the three-dimensional flowfield and even less about the effect of Reynolds number and Mach number on these flowfields. The classifications and supporting data presented in this report can serve as a starting point as new research explores swept-wing aerodynamics with ice shapes. As further results are available, it is expected that these classifications will need to be updated and revised.

  5. Assessing the dependence of bulk ice properties from probes with anti-shatter tips on environmental conditions

    NASA Astrophysics Data System (ADS)

    Jackson, Robert C.

    Ice clouds have significant impacts on the Earth's radiative budget. Their radiative impact highly depends on ice cloud microphysical properties. Climate and weather prediction models have to make certain assumptions about how the various processes are represented. Observations of how cloud properties vary with environmental conditions can help evaluate some parameterizations used in models. However, sufficient data are not available to characterize how ice crystal properties vary as a function of environmental conditions. Furthermore, many of these assumptions are derived from historical datasets collected by in situ probes, namely optical array probes that can be contaminated by shattered artifacts generated by large particles shattering on the probe tips and inlets. Therefore this study has two main objectives. Prior estimates of ice crystal size distributions derived from 2D Cloud Probes (2DCs) have been artificially amplified by small ice crystals generated from the shattering of large ice crystals on the probe tips. Although anti-shatter tips and algorithms exist, there is considerable uncertainty in their effectiveness. Therefore, this thesis first examines the differences in ice crystal size distributions, and bulk and optical properties from adjacent 2DCs with standard and anti-shatter tips, and processed with and without anti-shattering algorithms. The measurements were obtained from the National Research Council of Canada Convair-580 during the 2008 Indirect and Semi-Direct Aerosol Campaign (ISDAC) and the National Center for Atmospheric Research C-130 during the 2011 Instrumentation Development and Education in Airborne Science 2011 (IDEAS-2011). The 2DC size distributions are compared with those from the Holographic Detector for Clouds (HOLODEC), which has anti-shatter tips and allows for identification of shattering through spatial statistics. The ratio of the number concentration N of particles with maximum dimensions 125 to 500 mum from the 2DC with

  6. Simultaneous radar and aircraft observations of mixed-phase cloud at the 100-m-scale

    NASA Astrophysics Data System (ADS)

    Field, P.; Hogan, R.; Brown, P.; Illingworth, A.; Choularton, T.; Kaye, P.; Hirst, E.; Greenaway, R.

    2003-04-01

    Determination of cloud phase is important for predicting the radiative impact of clouds. Previous work by some of the authors has shown that even the presence of thin (~100 m) supercooled liquid layers above and below ice cloud significantly increase the reflection of solar radiation to space. We present 100-m-scale in situ and simultaneous radar observations of mixed-phase clouds over the UK. Particle sphericity, as determined by the aircraft mounted Small Ice Detector, appears to be a good indication of phase in these types of cloud where any newly produced ice will quickly grow in highly ice supersaturated conditions into non-spherical particles. During 1-d aircraft transects the dominant phase of the cloud was determined in contiguous 100 m horizontal segments. The resulting structure reveals that mixed-phase clouds can exhibit alternating regions of ice and liquid of varying horizontal scale that may be the result of the 1-d transect of the aircraft intercepting undulating liquid layers or turbulent activity. High differential reflectivity signals measured by the radar can be indicative of the nearby presence of liquid water giving rise to highly ice saturated conditions conducive to the growth of pristine crystals with high axial ratios. Although this is the case for discrete cloud layers it is not always true within a deep frontal cloud.

  7. NASA's rotorcraft icing research program

    NASA Technical Reports Server (NTRS)

    Shaw, Robert J.; Reinmann, John J.; Miller, Thomas L.

    1988-01-01

    The objective of the NASA aircraft icing research program is to develop and make available icing technology to support the needs and requirements of industry for all weather aircraft designs. While a majority of the technology being developed is viewed to be generic (i.e., appropriate to all vehicle classes), vehicle specific emphasis is being placed on the helicopter due to its unique icing problems. In particular, some of the considerations for rotorcraft icing are indicated. The NASA icing research program emphasizes technology development in two key areas: ice protection concepts and icing simulation (analytical and experimental). The NASA research efforts related to rotorcraft icing in these two technology areas will be reviewed.

  8. Near-infrared spectroscopy of ices under conditions relevant to interstellar and planetary environments

    NASA Astrophysics Data System (ADS)

    Richey, Christina R.

    The abundances of ices in planetary environments are obtain ed through measurements of near-infrared absorption features (n? = 10,000-4,000 cm-1 , λ1-2.5 μm), and near-IR measurements of materials present in the interstellar medium are increasingly common. In the studies presented here, the near-IR band strengths for molecules are determined through correlations to their better-known mid-IR characteristics. These strengths are used to determine the column densities of molecules in interstellar dense clouds or other environments from observed data. The first set of experiments focused on the near-IR features of molecules relevant to the study of interstellar icy grain mantles and planetary bodies: CO, CO 2 , C3 O2 , CH4 , H2 O, CH 3 OH, and NH3 . The spectra of these species were studied in the near-IR region from 10,000-4,000 cm-1 and in the mid-IR region from 4,000-400 cm-1 after the slow growth of films at ˜5K. The results were then used the results to determine the near-IR band strengths of each molecule. Many icy satellites have surfaces that are dominated by either N2 or H2 O, and ices in the ISM are primarily composed of H2 O. The second set of experiments is focused on the near-IR absorption features of CO, CO2 , CH4 , and NH 3 diluted in H2 O and diluted in N2 . Since the compositions of icy planetary bodies and interstellar ices are affected by processing due to UV light and proton bombardment, spectra of UV photolyzed and proton irradiated ices of N2 + CO2 and H2 O + CO2 have been collected to determine the extent of energetic processing on icy bodies in the outer solar system. These studies have shown that planetary ices are best represented by laboratory analogs comprised of mixed, energetically processed ices.

  9. Effect of Intercycle Ice Accretions on Airfoil Performance

    NASA Technical Reports Server (NTRS)

    Broeren, Andy P.; Bragg, Michael B.; Addy, Harold E., Jr.

    2003-01-01

    This paper presents the results of an experimental study designed to characterize and evaluate the aerodynamic performance penalties of residual and intercycle ice accretions that result from the cyclic operation of a typical aircraft deicing system. Icing wind tunnel tests were carried out on a 36-inch chord NACA 23012 airfoil section equipped with a pneumatic deicer for several different FAR 25 Appendix C cloud conditions. Results from the icing tests showed that the intercycle ice accretions were much more severe in terms of size and shape than the residual ice accretions. Molds of selected intercycle ice shapes were made and converted to castings that were attached to the leading edge of a 36-inch chord NACA 23012 airfoil model for aerodynamic testing. The aerodynamic testing revealed that the intercycle ice shapes caused a significant performance degradation. Maximum lift coefficients were typically reduced about 60% from 1.8 (clean) to 0.7 (iced) and stall angles were reduced from 17 deg. (clean) to 9 deg. (iced). Changes in the Reynolds number (from 2.0 x 10(exp 6) to 10.5 x 10(exp 6) and Mach number (from 0.10 to 0.28) did not significantly affect the iced-airfoil performance.

  10. Enhancing Icing Training for Pilots Through Web-Based Multimedia

    NASA Technical Reports Server (NTRS)

    Fletcher, William; Nolan, Gary; Adanich, Emery; Bond, Thomas H.

    2006-01-01

    The Aircraft Icing Project of the NASA Aviation Safety Program has developed a number of in-flight icing education and training aids designed to increase pilot awareness about the hazards associated with various icing conditions. The challenges and advantages of transitioning these icing training materials to a Web-based delivery are discussed. Innovative Web-based delivery devices increased course availability to pilots and dispatchers while increasing course flexibility and utility. These courses are customizable for both self-directed and instructor-led learning. Part of our goal was to create training materials with enough flexibility to enable Web-based delivery and downloadable portability while maintaining a rich visual multimedia-based learning experience. Studies suggest that using visually based multimedia techniques increases the effectiveness of icing training materials. This paper describes these concepts, gives examples, and discusses the transitional challenges.

  11. Aircraft-type dependency of contrail evolution

    NASA Astrophysics Data System (ADS)

    Unterstrasser, S.; Görsch, N.

    2014-12-01

    The impact of aircraft type on contrail evolution is assessed using a large eddy simulation model with Lagrangian ice microphysics. Six different aircraft ranging from the small regional airliner Bombardier CRJ to the largest aircraft Airbus A380 are taken into account. Differences in wake vortex properties and fuel flow lead to considerable variations in the early contrail geometric depth and ice crystal number. Larger aircraft produce contrails with more ice crystals (assuming that the number of initially generated ice crystals per kilogram fuel is constant). These initial differences are reduced in the first minutes, as the ice crystal loss during the vortex phase is stronger for larger aircraft. In supersaturated air, contrails of large aircraft are much deeper after 5 min than those of small aircraft. A parameterization for the final vertical displacement of the wake vortex system is provided, depending only on the initial vortex circulation and stratification. Cloud resolving simulations are used to examine whether the aircraft-induced initial differences have a long-lasting mark. These simulations suggest that the synoptic scenario controls the contrail cirrus evolution qualitatively. However, quantitative differences between the contrail cirrus properties of the various aircraft remain over the total simulation period of 6 h. The total extinctions of A380-produced contrails are about 1.5 to 2.5 times higher than those from contrails of a Bombardier CRJ.

  12. Trophic Status, Ecological Condition and Cyanobacteria Risk of New England Lakes and Ponds Based on Aircraft Remote Sensing.

    EPA Science Inventory

    Aircraft remote sensing of freshwater ecosystems offers federal and state monitoring agencies an ability to meet their assessment requirements by rapidly acquiring information on ecosystem responses to environmental change for water bodies that are below the resolution of space...

  13. A review of ice accretion data from a model rotor icing test and comparison with theory

    NASA Technical Reports Server (NTRS)

    Britton, Randall K.; Bond, Thomas H.

    1991-01-01

    An experiment was conducted by the Helicopter Icing Consortium (HIC) in the NASA Lewis Icing Research Tunnel (IRT) in which a 1/6 scale fuselage model of a UH-60A Black Hawk helicopter with a generic rotor was subjected to a wide range of icing conditions. The HIC consists of members from NASA, Bell Helicopter, Boeing Helicopter, McDonnell Douglas Helicopters, Sikorsky Aircraft, and Texas A&M University. Data was taken in the form of rotor torque, internal force balance measurements, blade strain gage loading, and two dimensional ice shape tracings. A review of the ice shape data is performed with special attention given to repeatability and correctness of trends in terms of radial variation, rotational speed, icing time, temperature, liquid water content, and volumetric median droplet size. Moreover, an indepth comparison between the experimental data and the analysis of NASA's ice accretion code LEWICE is given. Finally, conclusions are drawn as to the quality of the ice accretion data and the predictability of the data base as a whole. Recommendations are also given for improving data taking technique as well as potential future work.

  14. A review of ice accretion data from a model rotor icing test and comparison with theory

    NASA Technical Reports Server (NTRS)

    Britton, Randall K.; Bond, Thomas H.

    1991-01-01

    An experiment was conducted by the Helicopter Icing Consortium (HIC) in the NASA Lewis Icing Research Tunnel (IRT) in which a 1/6 scale fuselage model of a UH-60A Black Hawk helicopter with a generic rotor was subjected to a wide range of icing conditions. The HIC consists of members from NASA, Bell Helicopter, Boeing Helicopter, McDonnell Douglas Helicopters, Sikorsky Aircraft, and Texas A&M University. Data was taken in the form of rotor torque, internal force balance measurements, blade strain gage loading, and two dimensional ice shape tracings. A review of the ice shape data is performed with special attention given to repeatability and correctness of trends in terms of radial variation, rotational speed, icing time, temperature, liquid water content, and volumetric median droplet size. Moreover, an indepth comparison between the experimental data and the analysis of NASA's ice accretion code LEWICE is given. Finally, conclusions are shown as to the quality of the ice accretion data and the predictability of the data base as a whole. Recommendations are also given for improving data taking technique as well as potential future work.

  15. Test of prototype liquid-water-content meter for aircraft use

    NASA Technical Reports Server (NTRS)

    Gerber, Hermann E.

    1993-01-01

    This report describes the effort undertaken to meet the objectives of National Science Foundation Grant ATM-9207345 titled 'Test of Prototype Liquid-Water-Content Meter for Aircraft Use.' Three activities were proposed for testing the new aircraft instrument, PVM-100A: (1) Calibrate the PVM-100A in a facility where the liquid-water-content (LWC) channel, and the integrated surface area channel (PSA) could be compared to standard means for LWC and PSA measurements. Scaling constant for the channels were to be determined in this facility. The fog/wind tunnel at ECN, Petten, The Netherlands was judged the most suitable facility for this effort. (2) Expose the PVM-100A to high wind speeds similar to those expected on research aircraft, and test the anti-icing heaters on the PVM-100A under typical icing conditions expected in atmospheric clouds. The high-speed icing tunnel at NRC, Ottawa, Canada was to be utilized. (3) Operate the PVM-100A on an aircraft during cloud penetrations to determine its stability and practicality for such measurements. The C-131A aircraft of the University of Washington was the aircraft of opportunity for these-tests, which were to be conducted during the 4-week Atlantic Stratocumulus Transition Experiment (ASTEX) in June of 1992.

  16. An apparatus to measure frictional, anelastic, and viscous behavior in ice at temperate and planetary conditions.

    PubMed

    McCarthy, C; Savage, H M; Koczynski, T; Nielson, M A

    2016-05-01

    In this paper, we describe a cryogenic, servo-controlled biaxial friction apparatus designed to measure the deformational behaviors of ice. The apparatus is specifically designed to accurately achieve and measure the low differential stresses applicable to deforming ice on earth and on icy satellites. We can apply loads in the range ∼2-1800 kPa and velocities up to 4 mm/s, with resolution of 39 Pa and 0.7 μm, respectively. Precise temperature control, measurement, and insulation allow testing at constant temperature (from -2 to -30 °C) for prolonged periods of time. The apparatus is tested with various plastics as well as with polycrystalline ice samples and the results are consistent with previously published values. Critical components of the instrument are described along with examples of data collection schemes and preliminary results. The flexibility of the design allows for both glaciological and planetary applications over a range of deformational behaviors including friction, anelastic, and viscous. PMID:27250475

  17. High-resolution record of sea ice conditions in Fram Strait sheds new light on ice-ocean interactions and climate variability during the late glacial and Termination 1

    NASA Astrophysics Data System (ADS)

    Müller, Juliane; Stein, Ruediger

    2014-05-01

    Abrupt shifts in the palaeoceanographic setting in the subpolar North Atlantic and a hence significant climate variability characterised the transition from last glacial to deglacial and current interglacial conditions. Knowledge about the crucial role of sea ice coverage during these rapid climate reversals, however, is still limited. Herein we present a high-resolution reconstruction of the sea ice conditions that prevailed in eastern Fram Strait - the only deepwater passage permitting a substantial exchange of water and ice masses between the Arctic and the Atlantic Ocean - during the late glacial and deglacial period (i.e. from 29 ka to 9 ka BP). The joint analysis of the sea ice biomarker IP25 (Belt et al., 2007) and phytoplankton derived biomarkers allows to distinguish between different sea ice conditions and we further provide an even semi-quantitative assessment of the sea ice cover by means of the PIP25 index (Müller et al., 2011). Information about relative sea surface temperature changes is derived from the so-called DIP25 index (Cabedo-Sanz et al., 2013; Fahl & Stein, 2012). Importantly, the exceptional high temporal resolution of the studied sediment core permits the identification of a hitherto unknown variability in the sea ice coverage throughout the late glacial, which finally culminates in a permanent sea ice cover at the end of the Last Glacial Maximum (LGM). We suggest that the heat flow to the Nordic Seas during this critical time interval of Northern Hemisphere ice-sheet growth was rather pulse-like than continuous as is commonly assumed. This new observation of late glacial short-term fluctuations in the sea ice cover has considerable implications for palaeoceanographic proxy and model studies that focus on the LGM. Furthermore, we consider that the abrupt breakup of the perennial sea ice cover in Fram Strait at about 18 ka BP directly contributed to the weakening of the Atlantic Meridional Overturning Circulation (AMOC) during Heinrich

  18. Meteorological conditions in the Arctic Ocean in spring and summer 2007 as recorded on the drifting ice station Tara

    NASA Astrophysics Data System (ADS)

    Vihma, Timo; Jaagus, Jaak; Jakobson, Erko; Palo, Timo

    2008-09-01

    Meteorological observations were made at the drifting ice station Tara in the central Arctic Ocean from 23 March to 19 September 2007, constituting a unique data set from the season preceding the record-low sea ice extent. Comparisons of the Tara data with observations at the Russian drifting ice stations in 1937-1938 and 1950-1991 and at SHEBA in 1998 indicated that at Tara and SHEBA the atmospheric transmissivity for shortwave radiation was smaller than at the Russian stations, suggesting a higher cloud fraction or optical thickness. Compared to the mean conditions at the Russian stations, at Tara the melting season was twice as long and in April the 2-m air temperature was 7.0°C higher, but in July the 2-m temperature difference disappeared. The Tara tethersonde sounding data suggest that the air temperature at the altitudes of 200-1000 m was approximately 1°C higher than the mean of 1954-1985.

  19. Lifetime Extension of Cirrus Cloud Ice Particles upon Contamination with HCl and HNO3 under conditions of the Upper Troposphere and Lower Stratosphere

    NASA Astrophysics Data System (ADS)

    Rossi, Michel J.; Delval, Christophe

    2016-04-01

    Ice particles in the Upper Troposphere/Lower Stratosphere (UT/LS) are the seat of heterogeneous chemical processes that are important in polar ozone chemistry. Estimated evaporative lifetimes of typical pure ice particles of a few micrometers radius in Cirrus clouds are on the order of a minute or so at 80% relative humidity, too short to allow significant heterogeneous processing. We took this as a motivation to systematically measure absolute rates of evaporation and condensation of H2O in 1 to 2 micrometer thick ice films taken as proxies for small atmospheric ice particles under controlled conditions of HCl and HNO3 trace gas contamination. We have used a multidiagnostic reaction vessel equipped with residual gas mass spectrometry (MS), FTIR absorption spectroscopy in transmission and a quartz crystal microbalance (QCMB) in order to simultaneously observe both the gas and condensed phases under relevant atmospheric conditions. The rates (Rev(H2O)) or fluxes of evaporation (Jev(H2O)) of H2O from thin ice films contaminated by a measured amount of HCl in the range of 10% of a formal monolayer to 20 formal monolayers decreased by factors of between 2 and 50 depending on parameters such as temperature of deposition (Tdep), rate (RHCl) and dose (NHCl) of contaminant doping. Experiments with HCl fell into two categories as far as the decrease of Jev with the average mole fraction of contaminant (χHCl) in the remaining ice slab was concerned: one group where Jev(H2O) decreased gradually after pure ice evaporated, and another group where Jev(H2O) abruptly changes with χHCl after evaporation of excess ice. FTIR spectroscopy revealed an unknown, yet crystalline form of HCl hydrate upon HCl doping that does not correspond to a known crystalline hydrate. Of importance is the observation, that the equilibrium vapor pressure of these contaminated ices correspond to that of pure ice even after evaporation of excess ice at the characteristic rate of pure ice evaporation

  20. Laboratory and modeling studies on the effects of water and soot emissions and ambient conditions on the properties of contrail ice particles in the jet regime

    NASA Astrophysics Data System (ADS)

    Wong, H.-W.; Beyersdorf, A. J.; Heath, C. M.; Ziemba, L. D.; Winstead, E. L.; Thornhill, K. L.; Tacina, K. M.; Ross, R. C.; Albo, S. E.; Bulzan, D. L.; Anderson, B. E.; Miake-Lye, R. C.

    2013-10-01

    Contrails and contrail-induced cirrus clouds are identified as the most uncertain components in determining aviation impacts on global climate change. Parameters affecting contrail ice particle formation immediately after the engine exit plane (< 5 s in plume age) may be critical to ice particle properties used in large-scale models predicting contrail radiative forcing. Despite this, detailed understanding of these parametric effects is still limited. In this paper, we present results from recent laboratory and modeling studies conducted to investigate the effects of water and soot emissions and ambient conditions on near-field formation of contrail ice particles and ice particle properties. The Particle Aerosol Laboratory (PAL) at the NASA Glenn Research Center and the Aerodyne microphysical parcel model for contrail ice particle formation were employed. Our studies show that exhaust water concentration has a significant impact on contrail ice particle formation and properties. When soot particles were introduced, ice particle formation was observed only when exhaust water concentration was above a critical level. When no soot or sulfuric acid was introduced, no ice particle formation was observed, suggesting that ice particle formation from homogeneous nucleation followed by homogeneous freezing of liquid water was unfavorable. Soot particles were found to compete for water vapor condensation, and higher soot concentrations emitted into the chamber resulted in smaller ice particles being formed. Chamber conditions corresponding to higher cruising altitudes were found to favor ice particle formation. The microphysical model captures trends of particle extinction measurements well, but discrepancies between the model and the optical particle counter measurements exist as the model predicts narrower ice particle size distributions and ice particle sizes nearly a factor of two larger than measured. These discrepancies are likely due to particle loss and scatter

  1. Chemical Characterization of Individual Particles and Residuals of Cloud Droplets and Ice Crystals Collected On Board Research Aircraft in the ISDAC 2008 Study

    SciTech Connect

    Hiranuma, Naruki; Brooks, Sarah D.; Moffet, Ryan C.; Glen, Andrew; Laskin, Alexander; Gilles, Marry K.; Liu, Peter; MacDonald, A. M.; Strapp, J. Walter; McFarquhar, Greg

    2013-06-24

    Although it has been shown that size of atmospheric particles has a direct correlation with their ability to act as cloud droplet and ice nuclei, the influence of composition of freshly emitted and aged particles in nucleation processes is poorly understood. In this work we combine data from field measurements of ice nucleation with chemical imaging of the sampled particles to link aerosol composition with ice nucleation ability. Field measurements and sampling were conducted during the Indirect and Semidirect Aerosols Campaign (ISDAC) over Barrow, Alaska, in the springtime of 2008. In-situ ice nucleation measurements were conducted using a Continuous Flow Diffusion Chamber (CFDC). Measured number concentrations of ice nuclei (IN) varied from frequent values of 0.01 per liter to more than 10 per liter. Residuals of airborne droplets and ice crystals were collected through a counterflow virtual impactor (CVI). The compositions of individual atmospheric particles and the residuals were studied using Computer Controlled Scanning Electron Microscopy with Energy Dispersive X-ray analysis (CCSEM/EDX) and Scanning Transmission X-ray Microscopy coupled with Near Edge X-ray Absorption Fine Structure spectroscopy (STXM/NEXAFS). Chemical analysis of cloud particle residuals collected during an episode of high ice nucleation suggests that both size and composition may influence aerosol's ability to act as IN. The STXM/NEXAFS chemical composition maps of individual residuals have characteristic structures of either inorganic or black carbon cores coated by organic materials. In a separate flight, particle samples from a biomass burning plume were collected. Although it has previously been suggested that episodes of biomass burning contribute to increased numbers of highly effective ice nuclei, in this episode we observed that only a small fraction were effective ice nuclei. Most of the particles from the biomass plume episode were smaller in size and were composed of

  2. Will It Be Beneficial To Simulate the Antifreeze Proteins at Ice Freezing Condition or at Lower Temperature?

    PubMed

    Kar, Rajiv K; Bhunia, Anirban

    2015-09-01

    Antifreeze proteins (AFPs) enable the polar living species to survive subzero temperature conditions through effective lowering of the freezing point of body fluids. At the molecular level, AFPs directly interact with the growing seeds of ice crystals to inhibit their formation. To understand the structural and dynamic aspects of this interaction at the atomistic level, molecular dynamics (MD) simulations were carried out on several type I AFPs at multiple temperatures, including the physiologically relevant temperature of 273 K, a lower temperature of 227 K, and the conventional 300 K. A comparison of the principal component analysis (PCA) and mean squared deviation plots for Winter flounder AFP, HPLC6 (mutant of winter flounder AFP), Sculpin, and peptide 1m AFPs reveals that simulations at 273 and 227 K result in the formation of more conserved metastable states than at 300 K. Other parameters such as root-mean-square deviation (rmsd), solvent accessibility surface area (SASA), H-bonding and residual density function (RDF) also suggest the same. MD simulations with ice crystal, where AFPs are complexed to ice plane with TIP4P/ice water model, help in finding relevance of dynamic behavior, and physiological temperature becomes more pronounced. Additionally, a control study on a nonantifreeze protein (LL37) is included, which aids in exploring significant information. On the basis of this approach, it was found that AFPs at 273 and 227 K display relevant dynamic properties that appear at 300 K for nonantifreeze proteins. The present study hence emphasizes the importance of performing computational simulations for antifreeze proteins at the physiologically relevant temperature (273 K), and even at lower temperatures (like 227 K), rather than at room temperatures (300 K).

  3. Ice nucleating particles at a coastal marine boundary layer site: correlations with aerosol type and meteorological conditions

    NASA Astrophysics Data System (ADS)

    Mason, R. H.; Si, M.; Li, J.; Chou, C.; Dickie, R.; Toom-Sauntry, D.; Pöhlker, C.; Yakobi-Hancock, J. D.; Ladino, L. A.; Jones, K.; Leaitch, W. R.; Schiller, C. L.; Abbatt, J. P. D.; Huffman, J. A.; Bertram, A. K.

    2015-11-01

    Information on what aerosol particle types are the major sources of ice nucleating particles (INPs) in the atmosphere is needed for climate predictions. To determine which aerosol particles are the major sources of immersion-mode INPs at a coastal site in Western Canada, we investigated correlations between INP number concentrations and both concentrations of different atmospheric particles and meteorological conditions. We show that INP number concentrations are strongly correlated with the number concentrations of fluorescent bioparticles between -15 and -25 °C, and that the size distribution of INPs is most consistent with the size distribution of fluorescent bioparticles. We conclude that biological particles were likely the major source of ice nuclei at freezing temperatures between -15 and -25 °C at this site for the time period studied. At -30 °C, INP number concentrations are also well correlated with number concentrations of the total aerosol particles ≥ 0.5 μm, suggesting that non-biological particles may have an important contribution to the population of INPs active at this temperature. As we found that black carbon particles were unlikely to be a major source of ice nuclei during this study, these non-biological INPs may include mineral dust. Furthermore, correlations involving chemical tracers of marine aerosols and marine biological activity, sodium and methanesulfonic acid, indicate that the majority of INPs measured at the coastal site likely originated from terrestrial rather than marine sources. Finally, six existing empirical parameterizations of ice nucleation were tested to determine if they accurately predict the measured INP number concentrations. We found that none of the parameterizations selected are capable of predicting INP number concentrations with high accuracy over the entire temperature range investigated. This finding illustrates that additional measurements are needed to improve parameterizations of INPs and their

  4. Analysis and testing of the Diamond One wing anti-icing system

    NASA Astrophysics Data System (ADS)

    Yeoman, K. E.

    1985-01-01

    The Diamond One wing leading edge is protected against ice accretions by a bleed air anti-icing system. Three cross-sections selected for computer modeling considered the thermal mechanisms of convection, conduction, evaporation and sensible heating of impinged and runback water. With an instrumented aircraft, the model was refined using dry air and above freezing cloud flight test data. The refined model was exercised for wing surface temperature predictions for six critical icing conditions and found safe for natural icing flight testing. Measured natural icing test data was then inserted into the model to compare predicted vs. measured temperatures. Correlation was achieved and the system was accepted by FAA as safe for flight into known icing conditions.

  5. Deicing and Anti-Icing Unite

    NASA Technical Reports Server (NTRS)

    2002-01-01

    With funding from Glenn's Small Business Innovation Research (SBIR) program, Cox & Company, Inc., built an ice protection system that combines thermal anti-icing and mechanical deicing to keep airfoils (wings and other lifting surfaces) clear of ice. Cox's concept was to combine an anti-icing system with NASA's Electro-Mechanical Expulsion Deicing System, a mechanical deicer. The anti-icing element of this hybrid would reduce the aerodynamic losses associated with deicing systems. The Cox Low Power Ice Protection System is the first new aircraft ice protection system that has been approved by the Federal Aviation Administration for use on a business jet in 40 years. While the system is currently sized for Premier class aircraft, there are no apparent constraints prohibiting its use on aircraft of any size. The company is investigating further applications, such as adapting the system for unmanned aerial vehicles and other military aircraft.

  6. EOS Aqua AMSR-E Sea Ice Validation Program: Meltpond2000 Flight Report

    NASA Technical Reports Server (NTRS)

    Cavalieri, Donald J.

    2000-01-01

    This flight report describes the field component of Meltpond2000, the first in a series of Arctic and Antarctic aircraft campaigns planned as part of NASA's Earth Observing System Aqua sea ice validation program for the Advanced Microwave Scanning Radiometer (AMSR-E). This prelaunch Arctic field campaign was carried out between June 25 and July 6, 2000 from Thule, Greenland, with the objective of quantifying the errors incurred by the AMSR-E sea ice algorithms resulting from the presence of melt ponds. A secondary objective of the mission was to develop a microwave capability to discriminate between melt ponds and seawater using low-frequency microwave radiometers. Meltpond2000 was a multiagency effort involving personnel from the Navy, NOAA, and NASA. The field component of the mission consisted of making five 8-hour flights from Thule Air Base with a Naval Air Warfare Center P-3 aircraft over portions of Baffin Bay and the Canadian Arctic. The aircraft sensors were provided and operated by the Microwave Radiometry Group of NOAA's Environmental TechnologyLaboratory. A Navy ice observer from the National Ice Center provided visual documentation of surface ice conditions during each of the flights. Two of the five flights were coordinated with Canadian scientists making surface measurements of melt ponds at an ice camp located near Resolute Bay, Canada. Coordination with the Canadians will provide additional information on surface characteristics and will be of great value in the interpretation of the aircraft and high-resolution satellite data sets.

  7. Evaluation of NCAR Icing/SLD Forecasts, Tools and Techniques Used During The 1998 NASA SLD Flight Season

    NASA Technical Reports Server (NTRS)

    Bernstein, Ben C.

    2001-01-01

    Supercooled Large Droplet (SLD) icing conditions were implicated in at least one recent aircraft crash, and have been associated with other aircraft incidents. Inflight encounters with SLD can result in ice accreting on unprotected areas of the wing where it can not be removed. Because this ice can adversely affect flight characteristics of some aircraft, there has been concern about flight safety in these conditions. The FAA held a conference on in-flight icing in 1996 where the state of knowledge concerning SLD was explored. One outcome of these meetings was an identified need to acquire SLD flight research data, particularly in the Great Lakes Region. The flight research data was needed by the FAA to develop a better understanding of the meteorological characteristics associated with SLD and facilitate an assessment of existing aircraft icing certification regulations with respect to SLD. In response to this need, NASA, the Federal Aviation Administration (FAA), and the National Center for Atmospheric Research (NCAR) conducted a cooperative icing flight research program to acquire SLD flight research data. The NASA Glenn Research Center's Twin Otter icing research aircraft was flown throughout the Great Lakes region during the winters of 1996-97 and 1997-98 to acquire SLD icing and meteorological data. The NASA Twin Otter was instrumented to measure cloud microphysical properties (particle size, LWC (Liquid Water Content), temperature, etc.), capture images of wing and tail ice accretion, and then record the resultant effect on aircraft performance due to the ice accretion. A satellite telephone link enabled the researchers onboard the Twin Otter to communicate with NCAR meteorologists. who provided real-time guidance into SLD icing conditions. NCAR meteorologists also provided preflight SLD weather forecasts that were used to plan the research flights, and served as on-board researchers. This document contains an evaluation of the tools and techniques NCAR

  8. Aircraft surface coatings

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Liquid, spray on elastomeric polyurethanes are selected and investigated as best candidates for aircraft external protective coatings. Flight tests are conducted to measure drag effects of these coatings compared to paints and a bare metal surface. The durability of two elastometric polyurethanes are assessed in airline flight service evaluations. Laboratory tests are performed to determine corrosion protection properties, compatibility with aircraft thermal anti-icing systems, the effect of coating thickness on erosion durability, and the erosion characteristics of composite leading edges-bare and coated. A cost and benefits assessment is made to determine the economic value of various coating configurations to the airlines.

  9. UAV applications for thermodynamic profiling: Emphasis on ice fog research

    NASA Astrophysics Data System (ADS)

    Gultepe, Ismail; Heymsfield, Andrew J.; Fernando, Harindra J. S.; Hoch, Sebastian W.; Ware, Randolph

    2016-04-01

    Ice fog occurs often over the Arctic, cold climatic, and mountainous regions for about 30% of time where temperature (T) can go down to -10°C or below. Ice Nucleation (IN) and cooling processes play an important role by the controlling the intensity of ice fog conditions that affect aviation application, transportation, and local climate. Ice fog can also occur at T above -10°C but close to 0°C it occurs due to freezing of supercooled droplets that include an IN. To better document ice fog conditions, observations from the ice fog events of the Indirect and Semi-Direct Aerosol effects on Climate (ISDAC) project, Barrow, Alaska, Fog Remote Sensing And Modeling (FRAM) project Yellowknife, Northwest Territories, and the Mountain Terrain Atmospheric Modeling and Observations (MATERHORN) project, Heber City, Utah, were analyzed.. Measurements difficulties of small ice fog particles at cold temperatures and low-level flying restrictions prevent observations from aircraft within the surface boundary layer. However, unmanned Aerial Vehicles (UAVs) can be operated safely to measure IN number concentration, Relative Humidity with respect to ice (RHi), T, horizontal wind speed (Uh) and direction, and ice crystal spectra less than about 500 micron. Thermodynamic profiling by a Radiometrics Profiling Microwave Radiometer (PMWR) and Vaisala CL51 ceilometer was used to describe ice fog conditions in the vertical and its time development. In this presentation, ice fog characteristics and its thermodynamic environment will be presented using both ground-based and airborne platforms such as a UAV with new sensors. Some examples of measurements from the UAV for future research, and challenges related to both ice fog measurements and visibility parameterization will also be presented.

  10. Laboratory measurements of heterogeneous CO2 ice nucleation on nanoparticles under conditions relevant to the Martian mesosphere

    NASA Astrophysics Data System (ADS)

    Nachbar, Mario; Duft, Denis; Mangan, Thomas Peter; Martin, Juan Carlos Gomez; Plane, John M. C.; Leisner, Thomas

    2016-05-01

    Clouds of CO2 ice particles have been observed in the Martian mesosphere. These clouds are believed to be formed through heterogeneous nucleation of CO2 on nanometer-sized meteoric smoke particles (MSPs) or upward propagated Martian dust particles (MDPs). Large uncertainties still exist in parameterizing the microphysical formation process of these clouds as key physicochemical parameters are no